ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (147)
  • Articles: DFG German National Licenses  (147)
  • Cell & Developmental Biology
  • Chemical Engineering
  • Chemistry
  • Electrical and Electronics Engineering
  • Inorganic Chemistry
  • NDE
  • Superconductivity
  • modeling
  • Springer  (147)
  • 2015-2019
  • 1995-1999  (63)
  • 1980-1984  (84)
  • 1965-1969
  • 1940-1944
  • Electrical Engineering, Measurement and Control Technology  (116)
  • Technology  (25)
  • Medicine  (6)
Collection
  • Articles  (147)
Source
  • Articles: DFG German National Licenses  (147)
Keywords
Publisher
Years
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Simulation of Nanoparticle Production in Premixed Aerosol Flow Reactors by Interfacing Fluid Mechanics and Particle Dynamics (1999)
    Springer
    Journal of nanoparticle research 1 (1999), S. 305-315 
    Details
    ISSN: 1572-896X
    Keywords: particle population ; fluid mechanics ; flame synthesized aerosols ; CFD ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract The interaction of fluid mechanics and particle dynamics at the very early stages of flame synthesis largely affects the characteristics of the product powder. Detailed simulations provide a better understanding of these processes, which take place in a few milliseconds, and offer the possibility to influence the product characteristics by intelligent selection of the process parameters. The present paper reports on the simulation of titania powder formation by TiCl4 oxidation in an aerosol flow reactor. A commercially available fluid mechanics code is used for the detailed calculation of the fluid flow and the chemical reaction at non-isothermal conditions. This code is then interfaced with a model for aggregate particle dynamics neglecting the spread of the particle size distribution. The simulation shows the onset of the particle formation in the reactor and calculates the dynamic evolution of the aggregate particle size, number of primary particles per aggregate and the specific surface area throughout the reactor. The presented, newly developed calculation technique allows for the first time the simulation of particle formation processes under the authentic, complex conditions as found in actual aerosol reactors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010025121980
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Modeling and Spectroscopic Investigations on the Evaporation of Zirconia in a Thermal rf Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 341-362 
    Details
    ISSN: 1572-8986
    Keywords: Thermal rf plasma ; modeling ; spectroscopy ; plasma flash evaporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The evaporation process of zirconia powders injected in a thermal rf plasma is investigated. Both model calculations and optical emission spectroscopy are used to study the evaporation behavior. Gas temperatures and velocity distributions are determined numerically from conservation laws and Maxwell equations. The influence of plasma and particle parameters on the thermal history of entrained particles is discussed. Asymmetric Abel inversion is applied to detect asymmetric emission profiles in the plasma source. Spectroscopic measurements reveal that evaporated zirconium is concentrated near the axis of the plasma. Numerical calculations show that line-integrated emission profiles can be used to distinguish the cases of complete and incomplete evaporation. Axial emission profiles confirm that the evaporation zone is shifted upstream of the plasma when smaller precursor particles are used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021816302453
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Calculated Plasma Parameters and Excitation Spectra of High-Pressure Helium Discharges (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 467-486 
    Details
    ISSN: 1572-8986
    Keywords: He-plasma ; excitation spectra ; modeling ; comparison with experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A collisional-radiative model was used to study the kinetics of an atmospheric pressure helium discharge. The electron kinetics was obtained from a two-term solution of the Boltzmann equation with electron–electron collisions included. The distribution of the helium electronic excited states was compared to measured values and used to calculate excitation temperatures. The results show that a unique value of the excitation temperature cannot be used to characterize the whole electronic states distribution, because the plasma is not in local thermodynamical equilibrium under the conditions considered. Other calculated discharge parameters, such as the electron temperature, the maintenance electric field, the density of metastable atoms in the 2 3 S state, and the ion densities are presented and compared to experimental data when available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021878309471
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    CARS Diagnostic and Modeling of a Dielectric Barrier Discharge (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 445-466 
    Details
    ISSN: 1572-8986
    Keywords: Dielectric barrier discharge ; CARS on N2 and NO ; NO reduction ; chemical and vibrational kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Dielectric barrier discharges (DBD) with planar- and knife-shaped electrodes are operated in N2O2NO mixtures under a pressure of 20 and 98 kPa. They are excited by means of consecutive unipolar or bipolar high-voltage pulse packages of 10 kV at a pulse repetition rate of 1 and 2 kHz. The rotational and vibrational excitation of N 2 molecules and the reduction of nitric oxide (NO) in the discharge have been investigated using coherent anti-Stokes Raman scattering (CARS) technique. Rotational (gas) temperatures near the room temperature and vibrational temperatures of about 800 K at atmospheric pressure and 1400 K at a pressure of 20 kPa are observed. Therefore, chemical reactions of NO with vibrationally excited N 2 are probably insignificant. One-dimensional kinetic models are developed that balance 35 chemical reactions between 10 species and deliver equations for the population density of excited vibrational levels of N 2 together with a solution of the Boltzmann equation for the electrons. A good agreement between measured vibrational temperatures of N 2 , the concentration of NO, and calculated data is achieved. Modeling of the plasma discharge verifies that a DBD operated with a N2NO mixture reduces the NO content, the simultaneous presence of O 2 , already 1%, is enough to prevent the NO reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021826325400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Thinking in Levels: A Dynamic Systems Approach to Making Sense of the World (1999)
    Springer
    Journal of science education and technology 8 (1999), S. 3-19 
    Details
    ISSN: 1573-1839
    Keywords: levels ; complexity ; simulation ; modeling ; science education ; mathematics education ; dynamic systems ; systems thinking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract The concept of emergent "levels" (i.e., levels that arise from interactions of objects at lower levels) is fundamental to scientific theory. In this paper, we argue for an expanded role for this concept of levels in science education. We show confusion of levels (and "slippage" between levels) as the source of many of people's deep misunderstandings about patterns and phenomena in the world. These misunderstandings are evidenced not only in students' difficulties in the formal study of science but also in their misconceptions about experiences in their everyday lives. The StarLogo modeling language is designed as a medium for students to build models of multi-leveled phenomena and through these constructions explore the concept of levels. We describe several case studies of students working in StarLogo. The cases illustrate students' difficulties with the concept of levels, and how they can begin to develop richer understandings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009421303064
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Modeling Microbial Transport and Biodegradation in a Dual-porosity System (1999)
    Springer
    Transport in porous media 35 (1999), S. 49-65 
    Details
    ISSN: 1573-1634
    Keywords: modeling ; biodegradation ; microbial transport ; dual-porosity ; kinetics.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A mathematical model describing microbial transport and growth in a heterogeneous aquifer domain, composed of overlapping subdomains of high-permeability and low-permeability materials, is developed. Each material is conceptually visualized as a continuum which occupies the entire considered spatial aquifer domain. Based on the assumption that advection in the low-permeability domain is negligible, the mathematical model is solved by using a publically available reactive transport code. The importance of modeling microbial transport and growth in such a dual-porosity system is demonstrated through a hypothetical case study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006551627151
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Quantum Transition to Supersolid Phase (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 231-232 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; CDW ; supersolid ; coexistence ; Hubbard model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We study a possible coexistence of superconducting state and charge density waves which, in a broad sense, might be called a supersolid phase. We investigate the infinite dimensional (d=∞) attractive Hubbard model by applying a sublattice dependent Gutzwiller wave function $$g_{\text{A}}^{D_{\text{A}} } g_{\text{B}}^{D_{\text{B}} } |{\text{BCS}}$$ |BCS〉 as a variational wave function describing the ground state. One may naively expect that the BCS superconducting state evolves continuously to the Bose–Einstein condensed state of bipolarons as the attractive interaction increases, as far as the system is dilute. However, we show that our variational wave function has lower energy than the simple BCS wave function for all electron densities and the interaction strengths. Our variational parameters increase (g A,B→∞) as we increase the interaction strength (U→∞). The energy gap turns out to be a mixture of s and extended-s waves. In the vicinity of half-filling, we find a quantum transition from a simple superconducting phase to a supersolid phase with increase of the electron density and/or the interaction strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007747720269
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Studies on (Hg0.7Mo0.3)Sr2(Sr1−xLax)Cu2Oz with a Wide Range of Doping State (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 403-408 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; crystal structure ; Hg-based cuprate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The single-phased series of Sr-bearing Hg-1212 superconducting cuprate,(Hg0.7Mo0.3)Sr2(Sr1−x La x )Cu2O z has been prepared. X-ray diffraction showed that, the obtained samples belong to the 1212-structure with tetragonal space group P4/mmm, similar to that of (Hg, Mo)Sr2(Ca, Y)Cu2Oz, and stabilized in a wide compositional range of 0.25≤x≤0.75. Refinements of the structure are carried out in which the oxygen atoms at the (Hg, Mo) layer is shifted from high-symmetry position (0.5, 0.5, 0) to (x, x, 0). Magnetization and electrical resistivity measurements show that the as-prepared samples exhibit evidence for superconductivity and their superconducting properties were improved after O2 annealing with T onset c as high as 92 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007765718878
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    DC Electrical Resistivity Study of Granularity in YBa2CU3O7/Ag Composites (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 641-648 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Ag composites ; percolation ; granularity ; weak-link resistivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Temperature-dependent electrical resistivity in a set of YBa2Cu3O7−x /Ag composites, all prepared under an identical sintering schedule, is analyzed to extract granularity information. The weak-link resistivity ρ wl across the grain boundaries and the percolation factor α arising due to current frustration caused by misalignment of anisotropic grains and sample defects such as voids and cracks are estimated from the residual resistivity ρ0 and the temperature coefficient of resistivity dρ/dT. Variation of these parameters with Ag vol.% quantifying the extent of granularity indicates that granularity in the composites decreases and their electrical characteristics tend to be identical to that of Ag-free YBa2Cu3O7−x single crystals and epitaxial thin films as Ag vol.% approaches a value where onset of current percolation occurs through Ag channels. The increased α and decreased ρ wl observed at higher Ag vol.% explains the larger grains in the composites with narrow size distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022609432697
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effect of Ca Substitution on the Superconductivity of La2.5Y0.5CaBa3(Cu0.88Fe0.12)7O z (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 673-676 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; La2.5Y0.5CaBa3(Cu0.88Fe0.12)7O z ; compensated oxide ; magnetic pair breaking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The structural and superconducting properties of single-phase La2.5−y Y0.5Ca1+y Ba3 (Cu0.88Fe0.12)7O z (LYCaBCuFe) (y= 0.0−1.0) compounds with triple perovskite structure are investigated using X-ray diffraction, resistivity, a.c. susceptibility, and oxygen content measurements. Increasing Ca substitution for La resulted in a decrease in unit cell axes and volume. T c R=0 shows a marginal increase from 31 K to 37 K for y = 0.0−0.21 and thereafter it decreases with increasing y leading to zero T c R=0 at y ≥ 0.84. This shows that the suppression of T c from 80 K to 31 K by Fe doping at x = 0.12 La2.5Y0.5CaBa3(Cu1−x Fe x )7O z cannot be compensated by appropriate hole doping with Ca in LaYCaBCuFe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022620518584
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Superconductivity and Antiferromagnetic Order in ErNi2B2C Thin Films (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 707-712 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; antiferromagnetic order ; ErNi2Bi2C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Upper critical field and penetration depth of superconducting ErNi2B2C borocarbide thin films have been investigated and compared with the same properties of SmRh4B4 films. The coexistence of superconductivity and antiferromagnetic order is described through Machida's theory. A fairly satisfactory description of the experimental results is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022632921310
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    A Three-Dimensional Two-Phase Model for Thermal Plasma Chemical Vapor Deposition with Liquid Feedstock Injection (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 73-89 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasma ; CVD ; modeling ; liquid precursor ; diamond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper, a comprehensive model for thermal plasma chemical vapor deposition (TPCVD) with liquid feedstock injection is documented. The gas flow is assumed to be steady, of a single temperature. Radiation and charged species contributions are excluded, but extensive homogeneous and heterogeneous chemistry is included. The liquid phase is traced by considering individual droplets. Discussion on the model's application to diamond production from acetone in a hydrogen–argon plasma is included. The major conclusions are: (1) Liquid injection possesses a capability to deliver the hydrocarbon precursor directly onto the deposition target. (2) For the case of complete evaporation of the droplet before reaching the substrate, the deposition rate is similar to that obtained with gaseous precursors. (3) The computational results compare well with experimental data. The modeling results can be used to optimize the injection parameters with regard to the deposition rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021741310669
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    On the Correlation Between Deposition Rate and Process Parameters in Remote Plasma-Enhanced Chemical Vapor Deposition (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 189-214 
    Details
    ISSN: 1572-8986
    Keywords: Remote PECVD ; silicon dioxide ; modeling ; deposition rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Plasma-enhanced chemical vapor deposition has become one of the most important thin film deposition technologies. To avoid direct plasma exposure the substrates may be placed in the remote region. A carrier gas conveys the plasma energy to the deposition area where the reactions with the monomer molecules take place. For the engineering of such a process the modeling of the achievable deposition rate is of great interest. Among different possibilities semiempirical models provide a fast and easily utilizable tool without intensive computer simulations or the necessity of detailed knowledge about the chemistry involved. From deposition experiments with oxygen and an organosilicon monomer (hexamethyldisiloxane, HMDSO) the remote composite parameter is suggested. It combines microwave power, monomer and carrier gas flow rate, and the distance of the substrate from the plasma source. This parameter was derived from the ratio between atomic oxygen and monomer flow rate. In the parameter range considered the deposition rate is described as well ordered and the energy- and monomer-deficient regions are clearly separated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021698331973
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    A Mathematical Model of the Carbon Arc Reactor for Fullerene Synthesis (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 285-303 
    Details
    ISSN: 1572-8986
    Keywords: Fullerenes ; carbon arc ; plasma process ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A mathematical model of the carbon arc process for the synthesis of fullerenes (C 60 , C 70 ) is developed. The two-dimensional model solves for the velocities, temperature, and total concentration of carbon species. The net emission coefficient method is used for the radiation term. The carbon species conservation equations consider the evaporation of carbon from the anode, cathode surface deposition, and carbon condensation. The thermodynamic and transport properties are calculated as a function of temperature and carbon mass fraction, using the method of Chapman–Enskog. Erosion rates used by the model are determined experimentally. Calculated fields of the velocities, temperatures, carbon mass fraction and current intensity are presented. Comparison is made of the behavior of the arc at 1 and 4 mm interelectrode gaps, and between operation in argon and in helium. The results of simulations provide a justification for the higher yields observed in helium compared to the argon case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021658717860
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Modeling of H2 and H2/CH4 Moderate-Pressure Microwave Plasma Used for Diamond Deposition (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 325-362 
    Details
    ISSN: 1572-8986
    Keywords: Microwave plasma ; diamond deposition ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract One-dimensional transport models of moderate-pressure H 2 and H 2 /CH 4 plasmas obtained in a diamond deposition microwave reactor are presented. These models describe the plasma as a thermochemically nonequilibrium flow with three different energy modes. The solution of the one-dimensional plasma transport equations enabled the estimation of plasma species concentrations and temperatures on the axis of the reactor. As far as pure H 2 plasmas are concerned, results showed that the model predictions of gas and vibration temperatures are in good agreement with experimental measurements. The model also yields a relatively good qualitative prediction of the variations of H-atom mole fraction with the power density absorbed by the plasma. The results obtained for H 2 /CH 4 discharges showed that the model prediction on the variations of H-atom mole fraction with methane percentage in the discharge is in good qualitative agreement with experimental results. They also showed that methane is rapidly converted to acetylene before reaching the discharge zone. The concentrations of neutral hydrocarbon species in the reactor are mainly governed by thermal chemistry. The addition of methane strongly affects the ionization kinetics of the plasma. Three major ions are generally obtained in H 2 /CH 4 plasmas: C 2 H 2 + , C 2 H 3 + , and C 2 H 5 + . The relative predominance of these ions depends on the considered plasma region and on the discharge conditions. The ionic species concentrations are also mainly governed by chemistry, except very near the substrate surface. Finally the use of this transport model along with the surface chemistry model of Goodwin (1) enabled us to estimate the diamond growth rate for several discharge conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021845402202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Experimental and Theoretical Studies of a Pulsed Microwave Excited Ar/CF4 Plasma (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 429-446 
    Details
    ISSN: 1572-8986
    Keywords: Pulsed microwave discharge ; plasma ignition ; Ar/CF4 mixture ; plasma processing ; etching ; chemical kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The present work deals with a pulsed microwave discharge in an Ar/CF 4 gas mixture under a low pressure (1–10 mbar). The discharge chamber developed has a cylindrical geometry with a coupling window alternatively made of quartz or alumina. The setup allows one to investigate the plasma–wall interactions (here etching of the quartz window) and the ignition process of the pulsed microwave plasma. Microwave pulses with a duration of 50–200 μs and repetition rate between 1 and 10 kHz are typical for the experiments. The space-time behavior of the fluorine number density in the discharge has been investigated experimentally by optical actinometry. The discharge kinetics is modeled using electron-transport parameters and rate coefficients derived from solutions of the Boltzmann equation. Together with the solution of the continuity and electron balance equations and the rate equations describing the production of CF x (x=2, 3, 4) radicals and F atoms, a good agreement between experimental and theoretical data can be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021803114922
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Rare-Earths as Probes of High-Temperature Superconductivity (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 615-639 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; rare-earths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Using only two principles: (i) high-temperature superconductivity requires hypercharged oxygen, and (ii) the superconducting condensates are located in those parts of the crystal structures where they are unaffected by magnetic pair breaking, we are able to explain why certain rare-earth ions R are compatible with superconductivity and others are not, in the compounds RBa2Cu3O7, RBa2Cu4O8, RBa2Cu2NbO8, R2 − z Ce z CuO4, and R2 − z Ce z Sr2Cu2NbO10. Various defects are proposed as having central roles in the superconductivity or the suppression of superconductivity in these compounds. Many experiments for testing this physical picture are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022643531034
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Navy Programs in Superconducting Technology (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 1-4 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; magnets ; cryogenics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A review of U.S. Navy efforts in superconducting technology is given. Programs include development of superconducting magnets for motors in ship propulsion systems and to generate magnetic moments in mine sweeping systems. A program to develop superconducting quantum interference devices (SQUIDs) for detection of mines and buried ordnance has successfully been demonstrated. In electronic applications, superconducting filters, resonators, and antennae are being developed for radar, communication, and space systems. Concurrent with these superconductivity programs are efforts to improve the efficiency, reliability, and affordability of refrigeration systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022656620516
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Superconductivity and Critical Coupling in Non-Fermi Liquids (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 339-345 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; non-Fermi liquid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The critical temperature of a superconductor with a non-Fermi liquid ground state has been calculated. The density of states has two different forms and is energy dependent. The critical values of the coupling factor λ were calculated. The constant density of states results are obtained as particular cases. These results are an extension of the work done by Grosu et al. [Phys. Rev. B 56, 8298 (1997)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022694629696
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    The Effect of Nitrates on Thallium Based Oxycarbonate Superconductors (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 123-124 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Nitrates ; Oxycarbonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have synthesised a series of compounds in both the (PbTl)Sr4Cu2O7(CO3)1−y(NO3)y (0.1≤y≤0.5) and TlSr2Ba2Cu2O7(CO3)1−y(NO3)y (0.1≤y≤0.2) systems. We report the synthesis conditions of these materials, an X-ray diffraction analysis of their structure and the changes induced in superconducting behaviour produced by the introduction of nitrate groups into the starting composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022627222759
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Full Wafer In Situ Deposition of Thallium Lead Superconductors (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 129-132 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; TIPbSrCaCuO ; thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Thin films of (Tl,Pb)Sr2Ca0.8Y0.2Cu2O7, and (Tl,Pb)Sr2CuO5 can be grown in a single step process which involves sputter deposition from a mixed oxide target and simultaneous thermal evaporation of Tl2O. The use of a radiant heater has allowed extension of this in situ deposition process to full LaAlO3 and NdGaO3 wafers. Variations in the composition of the deposited film is 〈 4% across a 50 mm wafer while the thickness uniformity is ≍ 8%. The highest transition temperature for a (Tl,Pb)Sr2Ca0.8Y0.2 Cu2O7 film thus far is 83 K. The RMS surface roughness of (Tl,Pb)Sr2CuO5 films is uniform across the wafer and approximately 1% of the film thickness for films 20 to 100 nm thick.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022683307738
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of Hg1−xCrxSr2CuO4+δ Mercurocuprates (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 141-142 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; mercury ; chromium ; synthesis ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report preliminary results concerning the synthesis and structural characterisation of the chromium stabilised 1201 phases: Hg1−xCrxSr2CuO4+δ. A systematic study of the formation of phases in this system has been undertaken, together with a combined powder neutron and synchrotron x-ray diffraction study, to address the issue of chromium clustering and ordering in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022691509555
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Superconductivity in Lithium- and Sodium-Doped Mercury-Based Cuprates (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 169-171 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Alkali-doping ; Hg-based Cuprates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The effect of Na- and Li-doping in Hg-based cuprates has been studied. It has been found that superconductivity can be achieved in samples containing small amount of Na or Li. While little change is found in the crystalline structure, the formed superconducting phase have the onset Tc typically above 140 K and zero-resistance Tc up to 136K. More interestingly, the processing temperature for the doped Hg-1223 can be reduced significantly to near 700 °C which is promising for thin films growth on many technologically compatible substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022608113189
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Mixed-State Hall Effect in HgBa2CaCu2O6+δ Thin Films with Columnar Defects (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 163-167 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; thin film ; columnar defect ; pinning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The mixed state Hall effect has been studied in high quality HgBa2CaCu2O6+δ thin films while the pinning strength is modified by the irraddition of columnar defects. It has been shown that the pinning strength can be significantly improved by columnar defects. The sign reversal in Hall resistivity is found to be nearly independent of pinning while the scaling behavior between Hall resistivity (ρxy) and longitudinal resistivity (ρxx) is influenced by pinning. The exponent β in the scaling law β xy ∼ β xy β decrease from 1.8 ± 0.1 to 1.5 ± 0.1 as pinning is enhanced. This results suggest that the sign reversal and the scaling are unrelated, and pinning is not the mechanism of the sign reversal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022656029119
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Pulsing Interial Oscillation, Supercell Storms, and Surface Mesonetwork Data (1998)
    Springer
    Journal of engineering mathematics 34 (1998), S. 277-300 
    Details
    ISSN: 1573-2703
    Keywords: modeling ; supercell storm ; nonlinear ; inertial oscillation ; mesonetwork data.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract The pulsing inertial oscillation (PIO) model is a nonlinear, time-dependent, translating vortex solution of the inviscid, compressible fluid dynamic equations in the middle troposphere. The translation of this vortex during a pulse is strikingly similar to that of a supercell storm – a rotating thunderstorm that can generate tornadoes and hail. Two studies were performed to test the hypothesis that some supercell storms are manifestations of a PIO pulse. The first study applied the model to an intense interior draft whose buoyancy was bounded by a temperature excess of ± 12 K. The peak updraft speed achieved was 41·5 m s−1 and the peak Rossby number was 92·9. The study also pointed to an advanced concept for attaining higher values. The second study applied the PIO model to a supercell storm as a whole and succeeded in replicating its bulk properties, such as mesocylonic circulation, net mass and moisture influxes, and time track. This study also identified a critical feature of the PIO model that could be tested against storm data: The average vertical draft is downward before the turn in the storm track and upward afterwards. In the conventional theory, the average vertical draft is upward from storm inception until dissipation. These differing draft predictions were compared with the best available data, which are surface mesonetwork data. These data were found to support the PIO model. However, surface data alone are not conclusive, and further measurements are warranted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004319330013
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    New research opportunities in superconductivity IV (1997)
    Springer
    Journal of superconductivity and novel magnetism 10 (1997), S. 583-621 
    Details
    ISSN: 1557-1947
    Keywords: Superconductivity ; research opportunities ; state of the art
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This report surveys the considerable progress made over the last five years—such as the marketing of superconducting quantum interference devices (SQUIDs), cellular wireless filter systems, and high current leads—and assesses needs and opportunities in the areas of fundamental science, materials development, thin film and device applications, and wire and bulk applications. It examines the challenges facing high-temperature superconductivity: from the need to understand the mechanism of high-temperature superconductivity and the unusual “normal” state to the need for new instrumentation for material characterization. Advances in thin film and bulk materials are reviewed, and obstacles impeding the commercialization of HTS materials are examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02471924
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    The crystal field in rare earth based high-temperature superconductors (1997)
    Springer
    Journal of superconductivity and novel magnetism 10 (1997), S. 623-643 
    Details
    ISSN: 1557-1947
    Keywords: Superconductivity ; crystal field ; rare earth ; relaxation ; gap symmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Neutron spectroscopy is a powerful tool to determine unambiguously the crystal-field (CF) potential in rare-earth (R) based high-T c superconducting materials. This technique provides detailed information on the electronic ground state of the R ions which is important to understand the thermodynamic magnetic properties as well as the observed coexistence between superconductivity and long-range magnetic ordering of the R ion sublattice at low temperatures. Moreover, the decay of the antiferromagnetic state of the parent compound as well as the evolution of the superconducting state upon doping can be directly and quantitatively monitored. It is found that the observed CF spectra separate into different local components whose spectral weights distinctly depend on the doping level, i.e., there is clear experimental evidence for cluster formation. The onset of superconductivity can be shown to result from percolation which means that the superconductivity is an inhomogeneous materials property. Since the linewidths of CF transitions directly probe the static electronic susceptibility, we discuss temperature-dependent experiments of the relaxation rate of CF excitations in both optimally doped and underdoped regimes. It is shown that there is clear evidence for the opening of an electronic gap in the normal state of underdoped superconductors. Furthermore, the relaxation behavior appears to be extremely dependent upon the energy at which the static susceptibility is being probed. The main observed features can be reproduced by considering a strongly anisotropic gap function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02471925
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Modeling of a DC Plasma Torch in Laminar and Turbulent Flow (1997)
    Springer
    Plasma chemistry and plasma processing 17 (1997), S. 409-432 
    Details
    ISSN: 1572-8986
    Keywords: Plasma torch ; modeling ; laminar and turbulent flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A mathematical 2D representation is developed describing the temperature and the velocity profiles in a DC plasma torch and in the resulting plume. It is based on the resolution of conservation equations using the Simple method after Patankar. In the first part, we illustrate the effects of the turbulence, using, on the one hand, two Prandtl's mixing length models and, on the other hand, a standard k – ε model. We also show the influence of physical parameters like the inlet mass flow rate, the current intensity, and the kind of gas (argon or air) on the characteristics of the plasma. The second part of this study presents a comparison of the model with experimental results encountered in the literature. The profiles obtained at the exit of the torch are compared to the mathematical formulation used as boundary condition by the models taking into account only the plasma jet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021847113956
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    L.D.A. Simultaneous Measurements of Local Density and Velocity Distribution of Particles in Plasma Fluidized Bed at Atmospheric Pressure (1997)
    Springer
    Plasma chemistry and plasma processing 17 (1997), S. 433-452 
    Details
    ISSN: 1572-8986
    Keywords: Laser Doppler anemometry ; fluidized plasma bed ; particles velocity distribution ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Laser Doppler anemometry (L.D.A.) is an efficient and nonintrusive technique. Today, improved in its configuration, the L.D.A. has been applied even in flowing plasmas. (1,2) In-flight simultaneous measurements were performed for local density and velocity of particle distribution. The measurements provide an insight into thermal and mass transfer, chemical reactivity, and the distribution of residence times of particles in a plasma fluidized bed. The difficulties of L.D.A. in a plasma fludized bed such as high emission intensity of the plasma torch, high temperature, high particle density, and large distribution of particle granulometry were overcomed in the present investigation. The aims achieved were the characterization of the plasma fluidized bed distribution together with accurate measurements of local particle density and velocity as measured by L.D.A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021899130794
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    A 3-D Image Detection Method of a Surface Opening Crack in Concrete Using Ultrasonic Transducer Arrays (1997)
    Springer
    Journal of nondestructive evaluation 16 (1997), S. 193-203 
    Details
    ISSN: 1573-4862
    Keywords: Nondestructive evaluation ; NDE ; concrete ; crack ; image ; ultrasonic ; ellipsoid ; migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The detection of the size and the location of existing three dimensional cracks in a concrete structure is an important topic in civil engineering. In this paper, a multisource, multireceiver method that considers the travel times diffracted by a crack tip is introduced, to backcalculate a 3-D image of the crack tip of a surface opening crack. The possible location of the crack tip front is on the surface of an ellipsoid, which is constructed by a fixed travel time length measured from the source to the receiver, by letting the source and receiver points be the foci of the corresponding ellipsoid. If the locations of the source and the receiver, together with the associated measured travel time of the diffracted echo between each source-receiver pair are known, the image of the tip can be determined by counting the number of intersections of the ellipsoidal surfaces in an image construction cellular structure. The backcalculated crack tip image, as seen from experimental data, match the dimensions of the real crack very well, demonstrating the capability and accuracy of this newly proposed multisource, multireceiver method for concrete NDE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021843930620
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Part I: Toward a System of Educational Engineering for Traditional Class Elements: A Case Study in an Introductory Physics Course (1997)
    Springer
    Journal of science education and technology 6 (1997), S. 173-191 
    Details
    ISSN: 1573-1839
    Keywords: Science education ; educational engineering ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract In this paper, we present a system for formally characterizing elements of an introductory science class, measuring the performance of a class based on this characterization, and modeling the value of the class based on the measurements. This system allows the iterative improvement of any educational presentation through a model, test, iterate cycle. We propose formal practices involved in iteratively improving an educational experience be called educational engineering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022575606713
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Some Considerations on Modeling Heat and Mass Transfer in Porous Media (1997)
    Springer
    Transport in porous media 28 (1997), S. 233-251 
    Details
    ISSN: 1573-1634
    Keywords: capillary pressure ; conservation equations ; constitutive equations ; liquid water ; modeling ; thermodynamic equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this paper some considerations are presented about the equations needed to set up a model of the process of heat and mass transfer in porous media. A clear classification is made of the various types of equations used and of their physical meaning. Special attention is paid to the thermodynamic equilibrium equations and to their derivation since they are too often taken for granted. The importance of the various transport mechanisms (of mass and energy) is analyzed and the consequences that can arise when some term is neglected are indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006525729566
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Single Phase Flow in Partially Fissured Media (1997)
    Springer
    Transport in porous media 28 (1997), S. 285-306 
    Details
    ISSN: 1573-1634
    Keywords: fissured media ; homogenization ; dual porosity ; modeling ; microstructure ; porous media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract Totally fissured media in which the individual cells are isolated by the fissure system are effectively described by double porosity models with microstructure. Such models contain the geometry of the individual cells in the medium and the flux across their interface with the fissure system which surrounds them. We extend these results to a dual-permeability model which accounts for the secondary flux arising from direct cell-to-cell diffusion within the solid matrix. Homogenization techniques are used to construct a new macroscopic model for the flow of a single phase compressible fluid through a partially fissured medium from an exact but highly singular microscopic model, and it is shown that this macroscopic model is mathematically well posed. Preliminary numerical experiments illustrate differences in the behaviour of solutions to the partially fissured from that of the totally fissured case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006562120265
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Part II: A Computationally Based Modeling System for Class Elements Using Formal Observer-Based Experimental Connections (1997)
    Springer
    Journal of science education and technology 6 (1997), S. 193-211 
    Details
    ISSN: 1573-1839
    Keywords: Science education ; educational engineering ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract This article extends and refines the modeling system presented previously (Stewart, 1997). The initial system was sufficient for the optimization of delivery of education at a departmental level. This system is greatly more powerful, precise, and scientific, and fulfills the role of a modeling system for the research and development of educational practices. The model is applied to two widely diverse educational processes, Student Actions and Do Homework Problem, establishing the formalism and demonstrating its usefulness. The use of a rigorous computational syntax imposes completeness criteria on the modeling itself and uniformity. Experimental definition of the formation process of the patterns allows anyone to introduce new features of a model. This and the uniformity allows the models to become the property of the education community, not merely a single researcher, in the same way that mathematical models allow scientists to utilize and build upon previous research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022527723551
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Optimally Engineering Traditional Introductory Physics Classes (1997)
    Springer
    Journal of science education and technology 6 (1997), S. 297-314 
    Details
    ISSN: 1573-1839
    Keywords: Science education ; educational engineering ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract This paper presents a measurement of the time and resources committed to traditional student actions such as reading and working homework. The perception of the educational value of each basic action for both students and faculty is captured. From this information, basic educational efficiencies are computed for a traditional mechanics course and a non-traditional hands-on Electricity and Magnetism course. The calculations show an allocation of resources in the traditional course which uses the most student time in the least educationally valuable activity. The computed efficiencies also show overseen student note-taking as potentially a very valuable general tool. The techniques presented allow any institution to carry out quantitative educational engineering of their course offerings at the highest level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022502211969
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    New Research Opportunities in Superconductivity IV (1997)
    Springer
    Journal of superconductivity 10 (1997), S. 583-621 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; research opportunities ; state of the art
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This report surveys the considerable progress made over the last five years—such as the marketing of superconducting quantum interference devices (SQUIDs), cellular wireless filter systems, and high current leads—and assesses needs and opportunities in the areas of fundamental science, materials development, thin film and device applications, and wire and bulk applications. It examines the challenges facing high-temperature superconductivity: from the need to understand the mechanism of high-temperature superconductivity and the unusual “normal” state to the need for new instrumentation for material characterization. Advances in thin film and bulk materials are reviewed, and obstacles impeding the commercialization of HTS materials are examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022696328654
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    The Crystal Field in Rare Earth Based High-Temperature Superconductors (1997)
    Springer
    Journal of superconductivity 10 (1997), S. 623-643 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; crystal field ; rare earth ; relaxation ; gap symmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Neutron spectroscopy is a powerful tool to determine unambiguously the crystal-field (CF) potential in rare-earth (R) based high-T c superconducting materials. This technique provides detailed information on the electronic ground state of the R ions which is important to understand the thermodynamic magnetic properties as well as the observed coexistence between superconductivity and long-range magnetic ordering of the R ion sublattice at low temperatures. Moreover, the decay of the antiferromagnetic state of the parent compound as well as the evolution of the superconducting state upon doping can be directly and quantitatively monitored. It is found that the observed CF spectra separate into different local components whose spectral weights distinctly depend on the doping level, i.e., there is clear experimental evidence for cluster formation. The onset of superconductivity can be shown to result from percolation which means that the superconductivity is an inhomogeneous materials property. Since the linewidths of CF transitions directly probe the static electronic susceptibility, we discuss temperature-dependent experiments of the relaxation rate of CF excitations in both optimally doped and underdoped regimes. It is shown that there is clear evidence for the opening of an electronic gap in the normal state of underdoped superconductors. Furthermore, the relaxation behavior appears to be extremely dependent upon the energy at which the static susceptibility is being probed. The main observed features can be reproduced by considering a strongly anisotropic gap function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022654312724
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Modeling of phlebothrombosis (1997)
    Springer
    Bulletin of experimental biology and medicine 124 (1997), S. 1151-1153 
    Details
    ISSN: 1573-8221
    Keywords: thrombosis ; modeling ; external jugular vein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A new model of phlebothrombosis has been developed. Thrombotic mass in preparedin vitro by mixing dog's blood with thrombin. Retracted clot is injected transcutaneously in ligated segment of the jugular vein. The veins are examined visually and microscopically 1, 3, 5, 7, 10, and 14 days after injection. It is found that the thrombus is loosely bound to the vascular wall within 8–10 days. Endothelial desquamation starts on the 3rd–5th day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445688
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Monitoring and modeling of coastal waters in support of environmental preservation (1996)
    Springer
    Journal of marine science and technology 1 (1996), S. 75-84 
    Details
    ISSN: 1437-8213
    Keywords: monitoring ; modeling ; environmental preservation ; navigation ; nazardous spills ; tidal prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The improved monitoring and modeling capability resulting from recent technological advances in oceanographic sensors, computer processing power, and telecommunications can play a major role in environmental preservation. In particular, this capability can help improve: safe navigation and thus the prevention of maritime accidents that lead to hazardous spills; the effective cleanup of hazardous spills when they do occur; the real-time assessment of water quality problems; the assessment of long-term trends and variability due to both anthropogenic and climate change effects; and the understanding of key physical, chemical, and ecological processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391163
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    On the plasma chemistry of the C/H system relevant to diamond deposition processes (1996)
    Springer
    Plasma chemistry and plasma processing 16 (1996), S. 173-185 
    Details
    ISSN: 1572-8986
    Keywords: Diamond synthesis ; atomic hydrogen ; modeling ; mass spectrometry ; pulsed rf discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The chemistry of hydrogen-rich hydrocarbon-hydrogen mixtures is of primary interest for the understanding of the low-pressure synthesis of diamond. We per formed experiments under well-defined conditions like temperature, pressure, initial gas composition, etc. The gas composition at the end of a flow reactor was analyzed by a calibrated mass spectrometer and compared to results obtained from the Chemkin computer code. Residence thne in the reactor as well as other process parameters were similar to those of diamond-growing PA CVD processes performed earlier with the same experimental set-rip. Modeling and experiment under isothermal conditions show quantitative agreement. We realized time-resolved mass .spectrometry by means of a helium-flushed gas sampling probe. There is evidence that the commonly used reaction kinetic data for the dissociation C2H6 (+ M) ⇔ 2CH,(+M) gives 2 too small C2H4 concentrations for hydrogen-rich conditions. This could be attributed to the poorly known third-body efficiencies of the H2 molecules compared to Ar or C2H6 from which kinetic data are commonly derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01570176
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Hybridomas in a bioreactor cascade: modeling and determination of growth and death kinetics (1996)
    Springer
    Cytotechnology 21 (1996), S. 263-277 
    Details
    ISSN: 1573-0778
    Keywords: hybridomas ; serum-free medium ; monoclonal antibodies ; reactor series ; kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Hybridomas were cultured under steady-state conditions in a series of two continuous stirred-tank reactors (CSTRs), using a serum-free medium. The substrate not completely converted in the first CSTR, was transported with the cells to the second one and very low growth rates, high death rates, and lysis of viable cells were observed in this second CSTR. These conditions are hardly accessible in a single vessel, because such experiments would be extremely time-consuming and unstable due to a low viability. In contrast to what is often observed in literature, kinetic parameters could thus be derived without the neccessity for extrapolation to lower growth rates. Good agreement with literature averages for other hybridomas was found. Furthermore, showing that the reactor series is a valuable research tool for kinetic studies under extreme conditions, the possibility to observe cell death under stable and defined steady-state conditions offers interesting opportunities to investigate apoptosis and necrosis. Additionally, a model was developed that describes hybridoma growth and monoclonal antibody production in the bioreactor cascade on the basis of glutamine metabolism. Good agreement between the model and the experiments was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365349
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Perceptions of chemistry: Why is the common perception of chemistry, the most visual of sciences, so distorted? (1996)
    Springer
    Journal of science education and technology 5 (1996), S. 193-201 
    Details
    ISSN: 1573-1839
    Keywords: Chemistry ; chemistry education ; multiple intelligences ; imagery ; visual-spatial thinking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General , Technology
    Notes: Abstract Chemistry has evolved from a science dominated by mathematics into a science highly dependent on spatial-visual intelligence. Yet the chemical content of introductory courses remains taught essentially the same as 40–50 years ago. Chemistry, today, is recognized by chemists as the molecular science. Yet, school chemistry is alienated from that perception. Thanks to the computer, young people are more comfortable with visual imaging than their instructors were at the same age. Thus the time is rife to reinvigorate chemistry education by means of the visual-spatial approach, an approach wholly in conformance with the way modern chemistry is thought about and practiced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Modeling primary substrate controlled biotransformation and transport of halogenated aliphatics in porous media (1996)
    Springer
    Transport in porous media 24 (1996), S. 203-220 
    Details
    ISSN: 1573-1634
    Keywords: biotransformation ; halogenated solvents ; anaerobic processes ; modeling ; cometabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In situ biorestoration is a groundwater remediation technique in which the indigenous aquifer bacteria are stimulated by injecting compounds to provide carbon source and energy. Stimulated bacteria may transform the target contaminants such as tetrachloroethylene (PCE) and trichloroethylene (TCE) into intermediate products. In this study, we developed a model to simulate the substrate-limited biotransformation of the halogenated solvents present in anoxic groundwater by sequential reductive dehalogenation under methanogenic conditions. The model consists of conservation of mass equations for the primary substrate, immobile indigenous biomass, organic solvents such as PCE and TCE, and their intermediate products trichloroethylene, dichloroethylene, and vinyl chloride. The utilization of primary substrate and the biotransformation of organic solvents are assumed to follow Monod kinetics. The limiting factor on bacterial growth is assumed to be the primary substrate. The microbial yield coefficient is determined from the stoichiometric equation describing the anaerobic process. The model is solved by using a finite difference technique. Results are presented for three different case studies: continuous injection of primary substrate (acetate), single-pulse injection, and double-pulse injection. The single-pulse or double-pulse injection techniques were found to be more effective than continuous injection of primary substrate. Double-pulse technique reduces the clogging of injection wells caused by excessive microbial growth around boreholes and achieves a more uniform distribution of microbial growth in the subsurface. In all cases target compounds were effectively removed. The results, however, indicate substantial levels of intermediate product accumulation. Numerical results of a simplified model which assumes an abundance of primary substrate and a constant population of biomass, compare favorably with experimental data reported in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00139845
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    The use of system identification techniques in the analysis of oculomotor burst neuron spike train dynamics (1996)
    Springer
    Journal of computational neuroscience 3 (1996), S. 347-368 
    Details
    ISSN: 1573-6873
    Keywords: oculomotor ; burst neurons ; system identification ; saccade ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Medicine , Physics
    Notes: Abstract The objective of system identification methods is to construct a mathematical model of a dynamical system in order to describe adequately the input-output relationship observed in that system. Over the past several decades, mathematical models have been employed frequently in the oculomotor field, and their use has contributed greatly to our understanding of how information flows through the implicated brain regions. However, the existing analyses of oculomotor neural discharges have not taken advantage of the power of optimization algorithms that have been developed for system identification purposes. In this article, we employ these techniques to specifically investigate the “burst generator” in the brainstem that drives saccadic eye movements. The discharge characteristics of a specific class of neurons, inhibitory burst neurons (IBNs) that project monosynaptically to ocular motoneurons, are examined. The discharges of IBNs are analyzed using different linear and nonlinear equations that express a neuron's firing frequency and history (i.e., the derivative of frequency), in terms of quantities that describe a saccade trajectory, such as eye position, velocity, and acceleration. The variance accounted for by each equation can be compared to choose the optimal model. The methods we present allow optimization across multiple saccade trajectories simultaneously. We are able to investigate objectively how well a specific equation predicts a neuron's discharge pattern as well as whether increasing the complexity of a model is justifiable. In addition, we demonstrate that these techniques can be used both to provide an objective estimate of a neuron's dynamic latency and to test whether a neuron's initial firing rate (expressed as an initial condition) is a function of a quantity describing a saccade trajectory (such as initial eye position).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00161093
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Feasibility and performance region modeling of analog and digital circuits (1996)
    Springer
    Analog integrated circuits and signal processing 10 (1996), S. 23-43 
    Details
    ISSN: 1573-1979
    Keywords: Macromodeling ; hieararchical design ; analog circuit design ; feasibility ; performance ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Hierarchy plays a significant role in the design of digital and analog circuits. At each level of the hierarchy it becomes essential to evaluate if a sub-block design is feasible and if so which design style is the best candidate for the particular problem. This paper proposes a general methodology for evaluating the feasibility and the performance of sub-blocks at all levels of the hierarchy. A vertical binary search technique is used to generate the feasibility macromodel and a layered volume-slicing methodology with radial basis functions is used to generate the performance macromodel. Macromodels have been developed and verified for both analog and digital blocks. Analog macromodels have been developed at three different levels of hierarchy (current mirror, opamp, and A/D converter). The impact of different fabrication processes on the performance of analog circuits have also been explored. Though the modeling technique has been fine tuned to handle analog circuits the approach is general and is applicable to both analog and digital circuits. This feature makes it particularly suitable for mixed-signal designs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713977
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Solutions of the Eliashberg equations with abnormally large values of 2Δ(0)/T C (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 59-64 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Eliashberg equations ; high-T c cuprates ; organic superconductors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We consider the Eliashberg equations with an electron-phonon matrix elementg(k, k, q) possessing a low-energy cutoffξ 1. In the superconducting state, we assume that this cutoff is bound from below by the superconducting gap 2Δ. We solve for Δ andξ 1 self-consistently, as a function of temperature, and find that the ratio 2Δ(0)/Tc is very large; for parameters that we consider realistic for the cuprates, this ratio is approximately 10. This calculation applies to materials where the mean free path is long (clean limit). We also find that a hysteretic behavior is in principle possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728426
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    A new series of mercury-based high-T c superconductors (Hg, W)Sr2(Y1−x Ca x )Cu2 (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 93-95 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; mercury-based superconductors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A new series of superconducting mercury-based layered cuprates has been synthesized. X-ray diffraction indicates that the compounds with formula Hg0.8W0.2Sr2Y1−x Ca x Cu2O6+δ (0.3≤x≤0.6) exhibit the 1212 structure with space groupP 4/mmm . The investigation of superconductivity determined by electrical resistance measurement shows that the superconducting transition temperature (T c , onset) of Hg0.8W0.2Sr2Y0.4Ca0.6Cu2O6+δ is up to 94 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728432
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Tuning of the Fermi level at the second subband of a superlattice of quantum wires in the CuO2 plane: A possible mechanism to raise the critical temperature (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 343-348 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; EXAFS ; superstructure ; quantum wires ; nonhomogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The structure of the stripes in Bi2Sr2CaCu22O8+y superconductor has been refined by polarized CuK-edge extended X-ray absorption fine structure (EXAFS). The distribution of Cu-O (planar) distances range from 1.87 Å to 1.96 Å. The results show that the in-plane CuO2 lattice distortions in the 1D modulation are large enough to form a potential barrier of widthW between the stripes of undistorted CuO2 lattice of widthL=15±0.5 Å. The calculations show that the maximum of the density of states formed by the second subband is tuned to the Fermi level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727276
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Effect of gold doping on the superconducting critical temperature and transition width in single-crystal YBa2Cu3Oδ (YBCO) (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 259-261 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; gold-doped YBa2Cu3O−δ ; transition temperature ; transition width
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Single-crystal YBa2Cu3O−δ (YBCO) has been made with some of the copper atoms in the copper-oxygen chains replaced by gold. The samples were made by a flux method. The gold concentration was determined by EDX (energy-dispersive X-ray spectroscopy) as a function of the nominal (i.e., flux) composition. Up to about 4.8% of all the copper atoms can be replaced by gold. The effect of the gold doping on the superconducting transition temperature (T c ) and the transition width (ΔT c ) were determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728312
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Metastable states of the 2223 phase in the Bi(Pb)SrCaCuO system (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 277-280 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Bi2Sr2Ca2Cu3O y ; microwave absorption ; critical temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract By the magnetically modulated microwave absorption method (MAMMA) we observed the modifications induced by different calcination temperatures (between 830°C and 870°C) on the 2223 phase formed in a system sintered at (855±5)°C with the starting composition Bi1.7Pb0.3Sr2Ca2Cu3O y . The presence of the 2223 phase in almost distinct states (consequently, multiple 2223 phases) in the same sample was observed. As the calcination temperature was increased up to 850°C, the highest temperature state of the 2223 phase intensified. Higher calcination temperatures resulted in the enhancement of other lower-temperature states. The homogeneity of the 2223 phase was greatly improved by annealing the samples at, 800°C for 5 min in a flowing nitrogen atmosphere. We labeled as “metastable” the lower-temperature states having excess oxygen, which, by easily losing the supplementary oxygen under the above annealing procedure, were shifted to higher temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727548
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Superconductivity in the cuprates as a consequence of antiferromagnetism and a large hole density of states (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 379-387 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; t-J and Hubbard models ; mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We briefly review a theory for the cuprates that has been recently proposed based on the movement and interaction of holes in antiferromagnetic (AF) backgrounds. A robust peak in the hole density of states (DOS) is crucial to produce a large critical temperature once a source of hole attraction is identified. The predictions of this scenario are compared with experiments. The stability of the calculations after modifying some of the original assumptions is addressed. We find that if the dispersion is changed from an antiferromagnetic band at half-filling to a tight-binding cosk x+cosk y narrow band at 〈n〉=0.87, the main conclusions of the approach remain basically the same i.e., superconductivity appears in the $$d_{x^2 - y^2 } $$ -channel andT c is enhanced by a large DOS. The main features distinguishing these ideas from more standard theories based on antiferromagnetic correlations are here discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727282
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Charge-transfer in YBa2Cu3O x (1996)
    Springer
    Journal of superconductivity 9 (1996), S. 563-570 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; charge transfer ; YBa2Cu3Ox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The charge-transfer hypothesis is shown to be inconsistent with data for YBa2Cu3Ox: (i) The two-step behavior ofT c(x) (with jumps from zero to ≈60 K and then to ≈90 K) is not reflected as a similar, statistically significant two-step behavior in the bond-valence-sum charge of cuprate-plane Cu ions (as once believed), (ii) as a consequence of the law of conservation of charge, the derivatives of the layer charges with respect to oxygen contentx for both the Ba-O layers and the charge-reservoir Cu-O chains have the opposite signs to those predicted, and (iii) the charge-transfer observed for superconducting YBa2Cu3Ox is not sufficient to produce superconductivity, as demonstrated by insulating PrBa2Cu3Ox, which has virtually the same layer charges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728235
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Resonant tunneling in normal metal-superconductor junctions: Low-voltage conductance features and excess current (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 71-78 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; resonant tunneling ; conductance ; energy gap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have studied the conductance of normal metal-superconductor junctions with a potential barrier on the interface containing localized electron states. The probabilities of the Andreev reflection and the quasiparticle transmission are calculated using a one-dimensional model with a single localized state. The conductance of the junctions with many localized states described by a uniform distribution of the bound state energies around the Fermi level is calculated in the low-temperature region. It is shown that the Andreev reflection processes assisted by the resonant tunneling result in new features of the conductance, such as a zerobias maximum, a low-energy gaplike structure, and a two-gap behavior of the conductance at applied voltages near the value corresponding to the energy gap of the superconductor. The current-voltage characteristics for high applied voltages reveal both an excess current and current deficit, depending on the parameters of the localized states and the transparency of the tunnel barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00732243
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Gap states in HTSC by infrared spectroscopy (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 437-440 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; gap ; infrared ; d-wave
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Recent infrared reflectance spectroscopy on high quality crystals of a number of HTSC systems shows thatall have finite conductivity in the frequency region of the superconducting gap. Results on untwinned YBCO from a number of laboratories show that this absorption is not due to experimental problems or sample-to-sample variations. Other materials also show absorption features in the gap region in the form of peaks. We discuss these results in terms of recent ideas of the effect of impurities in d-wave superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00722824
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Shadow bands in models of correlated electrons (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 475-478 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Hubbard Model ; Shadow Bands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A consequence of strong antiferromagnetic correlations in models of high-Tc cuprates is the appearance in photoemission (PES) calculations of considerable more weight above the Fermi momentum PF than expected for non-interacting electrons. This effect, qualitatively discussed by Kampf and Schrieffer under the name of “shadow bands”, is here quantitatively analyzed in the two dimensional Hubbard and t-J models using Monte Carlo and exact diagonalization techniques in the realistic strong coupling regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00722834
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    A simple theory for the cuprates: the Antiferro-magnetic van Hove scenario (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 483-486 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; t-J and Hubbard models ; Mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A model of weakly interacting hole quasiparticles is proposed to describe the normal state of the high temperature superconductors. The effect of strong correlations is contained in the dispersion of the holes. Many-body effects induce anomalous quasiparticleflat bands similar to those observed in recent angle-resolved photoemission experiments. A model of weakly interacting hole quasiparticles is proposed to describe the physics of carriers in the cuprates. The model predicts superconductivity in the dx2-y2 channel, with a typical Tc ∼ 100K. The concept of “optimal doping” appears naturally in this model, as well as a large ratio 2Δ/κT c ∼ 5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00722836
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Experimental determination of the symmetry of the order parameter in YBCO (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 491-494 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; pairing symmetry ; YBCO ; SQUID
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract At present, the symmetry of the order parameter in the high temperature superconductor YBCO is quite controversial. Recent experiments using SQUIDs and Josephson junctions appear to support competing theories, with some experiments supporting a dx2−y2 pairing symmetry for the order parameter and others a s-wave pairing symmetry. We note that a number of factors such as trapped flux, magnetic field gradients and SQUID asymmetries could lead such measurements astray. We use a Scanning SQUID Microscope and a time-reversal invariance test to resolve these experimental problems. We find the order parameter in YBCO has a time-reversal invariant dx2−y2 symmetric component. We estimate the amplitude of anyimaginary s-wave symmetric component to be less than 4% and anyreal s-wave component to be less than 82%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00722838
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Is the pseudogap in the high Tc cuprates evidence for dynamic van Hove Jahn-Teller effects? (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 579-582 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Pseudogap ; Structural Phase Transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Angle-resolved photoemission has demonstrated that in optimally doped YBa2Cu3O7 (YBCO) and Bi2Sr2CaCu2O8, the van Hove singularity (vHs) is pinned close to the Fermi level. Such a pinning was predicted by the vHs scenario, due to strong electron-phonon coupling. This coupling arises for a novel Jahn-Teller (JT) effect, in which a structural distortion splits the degeneracy of the two vHs's. In the lanthanum cuprates, there appears to be a sequence ofdynamic JT phases, possibly terminating in a low-temperature static JT phase. The highest-temperature JT phase corresponds to the onset of octahedral tilts in the La cuprates (pyramidal tilts in YBCO), and can be identified with the experimentally observed pseudogap phase. Here I will summarize recent experimental evidence for such a dynamic JT effect in the cuprates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727430
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Hole pockets in the doped 2D Hubbard model (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 617-618 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Hubbard Model ; Electronic Density ; Hole Pockets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The electronic momentum distribution n(k) of the two dimensional Hubbard model is studied for different values of the coupling U/t, electronic density 〈n 〉, and temperature, using quantum Monte Carlo techniques. A detailed analysis of the data on 8 × 8 clusters shows that features consistent with hole pockets at momenta k=(±π/2,±π/2,) appear as the system is doped away from half-filling. Our results are consistent with recent experimental data for the cuprates discussed by Aebi et al. (Phys. Rev. Lett.72, 2757 (1994)). In the range of couplings studied, the depth of the pockets is maximum at 〈n 〉 approximately 0.9, and it increases with decreasing temperature. The apparent absence of hole pockets in previous numerical studies of this model is explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727444
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Influence of hole filling by Ti on the superconductivity of YBa2Cu3O7−δ (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 373-375 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; oxygen content ; hole filling ; suppression ofT c
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The structural and superconducting properties of YBa2(CU1−x Ti x )3Oz samples are investigated using X-ray diffraction, ac susceptibility, and oxygen content measurements. The effect of increasing Ti concentration in YBa2(Cu1−x Ti x )3Oz lowers the oxygen content and decreasesT c, which is attributed to hole filling by Ti.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728174
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Sign reversal of the Hall effect in YBa2(Cu1−x )3O7−δ single crystals (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 383-389 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; YBa2(Cu1−x Co x )3O7−δ ; Hall effect ; Single crystals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have measured the in-plane Hall effect and in-plane resistivity of cobalt-doped YBa2Cu3O7−δ (YBCO) single-crystal samples. The concentration of cobalt ranged from 1 to 3%. As the applied field was varied, a sign reversal of the Hall resistivity was seen for 1 and 2% Co-doped samples, but not for the 3% sample. Our results are expressed in terms of conductivities, as recently recommended by the work of Dorseyet al. and Kopninet al. In the mixed state just below the superconducting transition temperatureT c, the Hall conductivityσ xy is the sum of two terms,C 1/H andC 2H, whereC 1 andC 2 are field-independent but temperature-dependent. As previously observed by Ginsberg and Manson for undoped YBCO, the coefficientC 1 is approximately proportional toτ 2 andC 2 is approximately linear inτ, whereτ = 1−(T/T c ). The values ofC 1 andC 2 are presented for each cobalt concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728176
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Chemical potential pinning near a van Hove singularity in the cuprates (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 659-660 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; van Hove Singularity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Fermi energy is shown to be pinned near a van Hove singularity for an extended doping range in the one-band and three-band Hubbard models as a consequence of filling dependent band renormalizations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727465
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Influence of long-range interactions on superconductivity and phase separation (1995)
    Springer
    Journal of superconductivity 8 (1995), S. 657-658 
    Details
    ISSN: 1572-9605
    Keywords: Superconductivity ; Charge Density Wave ; t-J Model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The t-J model is studied including a long-range 1/r repulsive interaction. It is observed that charge-density-wave states become stable as the strength of the 1/r term, Vcoul, is increased. Due to this effect, the domain of stability of the superconducting phase that appears near phase separation at Vcoul=0 is not enlarged by a 1/r interaction as naively expected. Nevertheless, superconductivity exists in a finite region of parameter space, even if phase separation is suppressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00727464
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Numerical modelling of the scattering of elastic waves in plates (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 89-106 
    Details
    ISSN: 1573-4862
    Keywords: scattering ; elastic waves ; Lamb waves ; shear waves ; finite difference methods ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper describes the application of finite difference methods to the calculation of the scattering of elastic waves. The emphasis is on cracklike defects in plates, and it is shown that a common numerical technique can span a range of wavelengths from Lamb waves to ultrasonic waves with many reflections from the surfaces of the plate. Quantitative results are given for the scattering of Lamb waves and ultrasonic shear waves from surface-breaking cracks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566400
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Some computational considerations in eddy-current NDE (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 39-42 
    Details
    ISSN: 1573-4862
    Keywords: Eddy current ; computer analysis ; numerical methods ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Theoretical calculations of eddy-current phenomena often involve the numerical evaluation of various integral expressions. A discussion of some of the possible evaluation methods and of the factors to be considered in choosing a method is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711099
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Ultrasonic reflection from a stressed interface (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 3-12 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonic ; stress measurements ; interfacial stress ; NiTi ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In seeking to develop an NDE technique for verifying the serviceability of NiTi couplers for plumbing unions, it was found that the reflection coefficient for a normally incident ultrasonic wave correlated with the stress level at the NiTi-tubing interface. Current theory pertaining to interface reflection is not complete but, even at present status, there is semiquantitative accord between theoretical predictions and normalized data for reflection coefficient versus stress level. These results are at fixed frequency and with comparable surface roughness. Variation of either frequency or surface roughness further affects the reflection coefficient. Current studies are being pursued to define this effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711095
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    The radiographic edge scattering distortion (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 75-88 
    Details
    ISSN: 1573-4862
    Keywords: object scattering ; edge scattering ; knife edge ; neutron radiography ; buildup factor ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Previously described scattering based edge distortions in optical density scans obtained from a neutron radiographic knife-edge image have been here confirmed using analog Monte Carlo simulation. In an attempt to estimate the effects of additional object scatter on such artifacts, the effect on the edge response of diffusely incident neutrons has been determined both empirically and by Monte Carlo simulation. The diffuse neutron incidence has been found to diminish the relative magnitude of the distortion, offering explanation for the infrequent observation of the corresponding edge scattering halo artifacts. The potential of this edge distortion as a diagnostic indicator of the buildup factor in radiography is suggested and examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566399
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Separation and characterization of stress levels and texture in metal sheet and plate: I. Principles and preliminary experiment (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 157-163 
    Details
    ISSN: 1573-4862
    Keywords: Residual Stress ; ultrasonics ; metals ; EMATs ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An approach is proposed for obtaining separate measures of stress anisotropy and texture in metal sheet or plate. The approach is based on the propagation characteristics ofSH n modes of ultrasonic waves. Experimental work has established that differences betweenSH 0 modes with orthogonal directions of propagation provide a measure of stress anisotropy that is insensitive to texture, with the restriction that the pseudosymmetry of the polycrystalline matrix of the sheet or plate is orthorhombic or higher. In the present work, it is argued that the differences between elastic constants associated with orthogonal directions of propagation of higher order modes should provide a meaningful measure of texture. The only requirement is that the texture be sufficiently well developed so that the following inequality is obeyed: ∣C′44−C′55∣〉0.002 $$\bar C$$ with $$\bar C$$ =1/2 (C′44+C′55). HereC′44 andC′55 are the effective shear moduli for planes normal to the sheet or plate surface and at right angles to each other. They are measurable by observing the differences between the phase velocities of theSH 0 and theSH n〉0 modes in the principal directions. By using Electromagnetic Acoustic Transducers (EMATs), the phase velocities can be deduced from the frequencies at which an SH mode of fixed wavelength is optimally excited. This approach has the advantage of being independent of specimen geometry and dimensions other than thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566221
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Application of ferromagnetic resonance probes to the characterization of flaws in metals (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 51-58 
    Details
    ISSN: 1573-4862
    Keywords: eddy current testing ; magnetic particle testing ; magnetic sensor ; ferromagnetic resonance ; microwave frequency ; surface flaws ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This article presents some results obtained in the characterization of surface flaws by means of probes using ferromagnetic resonance of yttrium iron garnets (FMR probes). These experiments on artificial flaws show that FMR probes operate like eddy current probes for nonmagnetic materials and like magnetic field sensors for magnetic ones. Consequently, the working distance is larger for magnetic materials (1000–1500 µm) than for nonmagnetic ones (100–300 µm). FMR probes have good sensitivity to narrow flaws, good spatial discrimination, and are sensitive to flaw width and depth. Vector analysis allows the separation of distance and flaw effect by phase analysis on nonmagnetic materials. On magnetic materials this phase separation does not exist and another procedure is suggested. These results, and in particular those obtained on ferromagnetic materials, point to the possibility of replacing some eddy current or magnetic particle inspections by tests with ferromagnetic resonance probes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566396
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Concrete crack depth meter using nonlinear ADC (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 127-131 
    Details
    ISSN: 1573-4862
    Keywords: Concrete NDT ; NL-ADC ; crack depth measurement ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper introduces the design and construction of an electronic hybrid signal processing meter that develops an output voltage proportional to the depth of a concrete crack. The circuit employs multiplication, squaring, and square-rooting functions by means of a special nonlinear ADC and counting scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566217
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Transform techniques for analysis of thermal wave propagation in anisotropic composite materials (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 149-155 
    Details
    ISSN: 1573-4862
    Keywords: NDE ; thermal waves ; anisotropy ; composites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A general formulation for solving the three-dimensional thermal diffusion equation in anisotropic media is presented. The method is based on two-dimensional Fourier transform techniques and can provide a physical insight into the problem. The analysis can easily be adapted to take into account arbitrary spatial variations of the excitation beam (i.e., a laser or an electron beam). Results obtained from propagation of thermal waves in composites are presented and followed by simulations for cases where the source function is defined. Propagation through an anisotropic slab is formulated and applied to specific cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566220
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Analytical solution for impedance change due to flaws in eddy current testing (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 197-202 
    Details
    ISSN: 1573-4862
    Keywords: Eddy current ; impedance ; flaw ; Green's function ; Born's limit ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Green's function is used in order to derive the analytical solution for the change in impedance due to a presence of the flaws in a conductor. This solution is applied to a cylindrical flaw and a spherical flaw whose radii are much smaller than the radius of the test coil. For both cases, the change in impedance is obtained within Born's limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566224
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    The interaction of ultrasound with contacting asperities: Applications to crack closure and fatigue crack growth (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 203-212 
    Details
    ISSN: 1573-4862
    Keywords: Acoustic diffraction ; acoustic transmission ; asperity contact ; crack closure ; fatigue cracks ; mode conversion ; NDE ; stress intensity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The partial contact of two rough fatigue crack surfaces leads to transmission, reflection, diffraction, and mode conversion of an acoustic signal at those contacts. This paper reviews recent experimental and theoretical efforts to understand and quantify such contact on actual fatigue cracks in greater detail. It is shown that the size and density of individual contacts, or asperities, can be estimated from acoustic measurements. Furthermore, it is shown that this information is useful to provide the static stress across a partially closed crack as well as the “effective” stress intensity range which activates fatigue crack propagation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566225
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Distributed strain measurement in a rectangular plate using an array of optical fiber sensors (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 23-27 
    Details
    ISSN: 1573-4862
    Keywords: Optical fiber sensor ; distributed strain ; sensor array techniques ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Single mode optical fiber waveguide has been used to determine the two-dimensional strain distribution on a simply supported rectangular plate. Each of the fifty individual fibers in the rectangular grid array attached to one surface of the plate yields a measurement of the strain integrated along the length of that fiber on the specimen. By using similar sensor information from all of the fibers, both the functional form and the amplitude of the distribution may be determined. Limits on the dynamic range and spatial resolution are indicated. Applications in the measurement of internal strain and the monitoring of physically small critical-structural components are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711097
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    An inverse problem technique for detecting irregular cavities in circular cylinders by infrared scanning (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 133-140 
    Details
    ISSN: 1573-4862
    Keywords: Thermography ; infrared scanning ; calibration ; inverse problem ; cavity detection ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An inverse problem technique has been developed for detecting irregular cavities in circular cylinders. In this method, the cavity is considered a part of the unknown geometry of the investigated system, and the evaluated temperature is used to locate this geometry. An auxiliary problem is introduced in the solution of this problem; and in the solution, the cavity wall is located by forcing the temperature to satisfy the condition imposed at the cavity. The new methodology is validated by an experiment presented in this paper, and the test results indicate that this method is highly successful in locating cavities. The accuracy of the method is closely related to the accuracy of the temperature that can be measured at the surface. A small error in the surface temperature results in a slight cavity error for deep cavities, while a shallow cavity is not severely affected by a surface temperature error. This method is particularly attractive in detecting shallow cavities in nondestructive evaluation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566218
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Electromagnetic crack detection in ferritic steel (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 165-175 
    Details
    ISSN: 1573-4862
    Keywords: Eddy current ; instrumentation ; probe design ; crack detection ; ferritic steel ; offshore ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The detection and sizing of fatigue cracks in ferritic materials, especially in offshore structures, is of major importance. This paper describes an eddy current system to detect such cracks, operating in an offshore environment with a search probe to electronic instrument separation of up to 600 m. An analysis of the various factors influencing the search coil behavior is given in terms of a mutually coupled primary and secondary electrical circuit; the component values of which are influenced by the coil design, induced electrical currents in the material, and any defects it contains. It is further shown that, with proper coil parameters, the phase variation in the phase angle of the coil complex impedance can be kept almost constant compared with the rapid variation occurring during lift-off. This behavior can be exploited in the instrumentation to give a clear vector display indication of the crack presence on less than ideal surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566222
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Acousto-optic method for nondestructive testing (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 43-50 
    Details
    ISSN: 1573-4862
    Keywords: Acousto-optic ; light diffraction ; ultrasonics ; phase measurements ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An alternative method for nondestructive testing based on light diffraction by ultrasonic waves is presented. It enables us to make more accurate measurements of intensity and phase of reflected waves, and therefore detailed information about the reflecting system can be obtained. Applications are numerous but special attention is payed to examination of the quality of coupling systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711100
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Some effects of the shape of a small defect in eddy-current NDE (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 59-63 
    Details
    ISSN: 1573-4862
    Keywords: eddy current ; theoretical models ; computer analysis ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Available theoretical models for predicting defect responses in eddy-current NDE apply only to defects of spheroidal shape. In this paper, the boundary-element integral-equation approach is extended to allow for defects of more irregular shape. Sample results for cylindrical and conical voids are presented and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566397
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Scattering of ultrasound in solids as visualized by the photoelastic technique (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 65-73 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonic scattering ; photoelastic visualization ; cylindrical cavities ; creeping wave ; cracks ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Our efforts in the past few years to visualize the scattering of ultrasound in solids by the photoelastic technique are briefly reviewed. Photoelastic photographs are presented showing the dynamic processes of scattering in glass of plane longitudinal or transverse waves by a cylindrical cavity or cavities as well as by two-dimensional surface-breaking or internal cracks. Phenomena like creeping and multiple scattering are clearly seen, in addition to some details which are not predicted by known theories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566398
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    The effects of focusing and refraction on Gaussian ultrasonic beams (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 107-123 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; transducers ; focusing ; refractior ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A scalar theory of the propagation of Gaussian ultrasonic beams through lenses and interfaces is presented. For radiation into a fluid, the Fresnel approximation is employed to derive the laws of propagation of Guassian beams (previously employed in the analysis of coherent optical systems). These are then generalized to situations commonly found in nondestructive evaluation by treating the effects of propagation through lenses and through curved interfaces at oblique incidence. A numerical example illustrates the ease with which insight into diffraction phenomena for complex geometries can be gained by this approach. The limitations imposed on the theory by aberrations and the scalar assumption are discussed, and the relationship of the Gaussian theory to the radiation of piston transducers is explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566401
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Flaw detection close to the interface using ultrasonic echography (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 141-148 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonic echography ; signal processing ; flaw detection ; nondestructive control ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The detection of flaws by ultrasonic echography becomes difficult when the flaw is at a shallow depth. The time delay between the interface and flaw echos is less than the width of the impulse-response time of the transducer, and the flaw echo generally has an amplitude much smaller than the dominating interface echo. When the surface is not too rough, the interface echo can be assumed to be known, and its comparison with the signal interface and flaw echo permits the detection of the flaw. In this article it is shown that signal processing techniques allow small flaws to be detected very close to the surface (∼0.5 mm). Two methods are proposed, the first one is based on the minimization of the mean-square error, and the second on the spectral substraction of the two echos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566219
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Eddy current solutions applicable to the problem of nondestructive inspection of flat and cylindrical surface layer (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 29-38 
    Details
    ISSN: 1573-4862
    Keywords: NDE ; eddy currents ; surface layers ; stratification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Nondestructive inspection of flat and long cylindrical metallic-surface layers is conveniently dealt with using the results of wave propagations in a one-dimensionally stratified medium. Analytical solutions for some special profiles are obtained, and perturbation technique is used to obtain results for more frequently encountered profiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711098
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Plasma polymerization of ethane. II. Theoretical analysis of effluent gas composition and polymer deposition rates (1983)
    Springer
    Plasma chemistry and plasma processing 3 (1983), S. 163-192 
    Details
    ISSN: 1572-8986
    Keywords: RF plasma ; plasma polymerization ; modeling ; theoretical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A theoretical model has been developed to describe the deposition of polymer occurring in a capacitatively coupled, low-pressure, RF discharge sustained in ethane. The reaction mechanism chosen for this model assumes that polymer formation is controlled by the formation of free radicals in the plasma and the subsequent reaction of these species at the surface of the electrodes used to sustain the plasma. Convective and diffusive transport is taken to occur in the direction parallel to the electrodes. Diffusive transport perpendicular to the electrodes is considered to be rapid, and hence the gradients in this direction are taken to be negligible. Both the composition of the gas leaving the plasma reactor and the axial profile of polymer deposition rate within the reactor, observed experimentally, are predicted accurately by the model. Results obtained from the model have also been used to estimate the kinetic chain length and degree of unsaturation in the polymer. Both predictions are found to be in reasonable agreement with experimental observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566019
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    The effects of low-ionization-potential contaminants on thermal plasmas (1983)
    Springer
    Plasma chemistry and plasma processing 3 (1983), S. 259-273 
    Details
    ISSN: 1572-8986
    Keywords: Electric arcs ; thermal plasmas ; contaminants ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Plasmas consisting of a high-ionization-potential component mixed with a low-ionization-potential contaminant are common in industrial processes. Modeling results are presented for a sodium-contaminated nitrogen plasma column operating either in a free-burning (low-temperature) mode or operating in a constricted (high-temperature) mode. At sufficiently high plasma temperatures, the behavior is dominated by the high-ionization-potential component's properties. The low-ionization-potential contaminant's properties determine the low-temperature plasma behavior even when the contaminant is present in relatively small quantities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566024
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Partial purification and characterization of the bone resorption factor fromActinomyces viscosus (1982)
    Springer
    Calcified tissue international 34 (1982), S. 49-53 
    Details
    ISSN: 1432-0827
    Keywords: Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Quantitative use of Rayleigh waves to locate and size subsurface holes (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 55-63 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; Rayleigh waves ; subsurface defects ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An ultrasonic inspection method is used to obtain the circumference of a subsurface hole and the depth of the hole below the surface. A pitch-catch Rayleigh wave transducer set-up was used to launch a Rayleigh surface wave at the flaw and to capture and record the scattered waves. The frequency spectrum of the scattered waves can be used to obtain the depth of the hole. The ligament of material between the hole and the surface is sent into resonance, and this feature can be extracted from the scattered waves' frequency spectrum. The frequency is a function of the ligament length; thus the hole depth can be obtained. The circumference of the hole is found from a time of flight measurement. A Rayleigh wave is formed that travels around the hole's surface. The length of time required for the wave to travel around the hole is a measure of the circumference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566955
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    The influence of skin depth on crack measurement by the ac field technique (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 65-76 
    Details
    ISSN: 1573-4862
    Keywords: crack measurement ; ac field technique ; arbitrary skin depth ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A general solution is given to describe the ac field around surface-breaking cracks for arbitrary values of the ratio of skin depth δ to crack depthd. This solution allows accurate interpretation of crack depth from voltage readings taken by a Crack Microgauge instrument in cases where δ andd are comparable. It is shown to agree with asymptotic formulae obtained for the cases where δ/d is very small and very large. Provided that the probe length Δ is large compared with δ, the calculations show that a very good approximation to the crack depth may be obtained, irrespective of the ratio δ/d, by using the thin-skin asymptotic formula $$d = \frac{1}{2}\Delta (V_2 - V_1 )/V_1 $$ whereV 1 andV 2 are probe voltages registered at positions just off and across the crack, respectively. The problem is solved for a crack of infinite aspect ratio which has no opening, but it can be applied with confidence at the centerline of cracks of fairly large aspect ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568962
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Infrared scanning thermography for a quantitative detection of cavities in a plane slab and a rectangular prism (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 99-109 
    Details
    ISSN: 1573-4862
    Keywords: thermography ; infrared scanning ; calibration ; inverse problems ; cavity detection ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An approach for treating nondestructive testing as the solution of inverse problems in mathematical physics has been used for the detection of cavities. The approach is developed based on the use of an additional boundary condition of scanned temperature on the surface to solve for the cavity geometry. For the present study, the condition at the cavity side is taken to be that of a specified temperature, and the experiment is carried out to meet this condition. Two specimens are tested in this paper, a plane slab and a rectangular prism. In both bodies the cavity is rectangular in shape. For the testing of the plane slab, the method is able to detect the cavity wall with high accuracy, whereas the cavity depth error is larger (6%). The detection of the cavity position in the rectangular prism has an error ranging from −9.7 to 7.7%. Errors in the experiment are attributed to the uncertainties in the measurements of temperature and the Biot number. The former is read off from the analog data output of the infrared scanner. The latter is not measured separately, but is computed from the scanned data and thus becomes a portion of the total nondestructive testing output. A final note is also made in this paper to relate how the presented method can be used in actual practice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568966
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Analysis of ultrasonic wave scattering for characterization of defects in solids: I. Spherical inclusions and reciprocity (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 175-182 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonic wave scattering ; inclusions ; reciprocity ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper, as part of a series on elastic wave scattering, presents results of measurements and calculations on scattering of ultrasonic waves by a solid spherical inclusion (tungsten carbide) embedded in titanium alloy by the diffusion bonding process. Both direct scattering and mode-converted scattering angular distributions are reported for shear and compressional incident waves. The consequences upon the signals when transmitter and receiver were interchanged are explored in a reciprocity rule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566558
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    The ac field around a plane crack in a metal surface when the skin depth is large (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 19-24 
    Details
    ISSN: 1573-4862
    Keywords: ac potential difference ; eddy current ; fatigue crack measurement ; skin effect equation ; large skin depth ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper considers the solution of the skin-effect or Helmholtz equation, ∇2ψ=k 2ψ, for the two-dimensional flow of a uniform alternating current perturbed by a plane crack of uniform depth. Herek is the ratio of crack depthd to skin depth δ. When the skin depth is large compared with the crack depth andk f 0, the quasi-static approach to this problem ignores the terms on the right-hand side and constructs solutions from Laplace's equation which are essentially dc solutions and are correct to orderk. In this paper we consider behavior near the limit when the skin depth is large and give solutions which are correct to orderk 2. In an example we relate the results to the interpretation of readings from an ac potential difference instrument applied to the measurement of surface-breaking cracks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566951
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Characterization of localized surface elastic defects by nonspecular reflection at the Rayleigh angle (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 93-98 
    Details
    ISSN: 1573-4862
    Keywords: bounded ultrasonic beam reflectivity ; Rayleigh angle ; beam profile ; surface defects ; nonspecular reflection ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The relationships between characteristics of elastic defects and nonspecular features of bounded ultrasonic beams reflected at the Rayleigh angle from a liquid-solid interface are investigated. The results can serve as a theoretical basis for interpretation of Rayleigh angle nonspecularly reflected beam profiles as characterization of localized surface elastic defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568965
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    On the optimum applied field for magnetic particle inspection using direct current (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 125-136 
    Details
    ISSN: 1573-4862
    Keywords: magnetic particle inspection ; magnetic leakage fields ; finite difference method ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Experimental measurements of leakage fields from cylindrical defects were obtained in a geometry which permitted simultaneous measurement of the magnetic induction of the material. The results obtained are compared with calculations using a nonlinear finite difference method. Both the experiments and the calculations indicate that the magnitude of the leakage field continues to grow nearly in proportion with the applied field well into the saturation region of the magnetic material. The implications for magnetic particle inspection are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566554
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Time domain Born approximation (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 45-53 
    Details
    ISSN: 1573-4862
    Keywords: Born approximation ; ultrasonic scattering ; NDE ; time domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The time domain Born approximation for ultrasonic scattering from volume flaws in an elastic medium is described. Results are given both for the direct and the inverse problem. The time domain picture leads to simple intuitive formulas, which we illustrate by means of several simple examples. Particular emphasis is given to the front surface echo and its use in reconstructing the properties of the flaw.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566954
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Quantitative characterization of flaws near a surface using inverse born approximation (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 183-188 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; Born inversion ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Quantitative reconstruction of volumetric flaws near a surface of an elastic solid has been carried out experimentally by analyzing the scattered ultrasonic waves. The inverse Born approximation (developed for flaws in bulk materials) was tested for the first time in the determination of the size, shape, and orientation of near-surface flaws. We have studied spherical solid inclusions at various depths below the surface. In addition we examined an approximately 2:1 prolate spheroidal inclusion which was located one major axis below the surface. The determination of the flaw's size, shape, and orientation in terms of an equivalent ellipsoid is realized by performing nonlinear least-squares iteration of the one-dimensional Born inversion results obtained at various scattering directions within a finite aperture. The reconstruction is in good agreement with the actual parameters of the flaw.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565863
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Probe characterization in ac field measurements of surface crack depth (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 9-17 
    Details
    ISSN: 1573-4862
    Keywords: ac potential difference ; probe characterization ; induction effect ; slots ; fatigue crack ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In the ac field method of crack depth measurement by the Crack Microgauge, the area of the loop formed in the probe gives rise to an induced voltage, which can introduce errors into the depth measurement. In this paper, a method for measuring the probe area is given, and the quality of the probe is thereby characterized. The underlying theory was given previously, and it is applied here to the probe characterization problem. The probe area is determined by two voltage measurements taken on an artificial rectangular flaw machined in an arbitrary metal. By measurements on several such specimens with the same probe, it is confirmed that the area so obtained is a characteristic of the probe and is independent of the specimen material. Thereafter, measurements on various rectangular flaws with probes of different characteristic area were taken, and very good agreement between predicted and real depths was achieved. Both theory and experiments show that probe characterization is of particular importance when this method is used to measure surface crack depths in metals of low permeability such as aluminum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566950
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Change in impedance of a single-turn coil due to a flaw in a conducting half space (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 37-43 
    Details
    ISSN: 1573-4862
    Keywords: eddy current ; impedance ; lift-off ; flaw ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The problem of detection and characterization of a flaw in a conducting half-space using an eddy-current coil oriented parallel to the interface is examined. An expression is derived for a first order approximation for the change in complex impedance due to a flaw located within the conducting medium. The overall impedance is a function of the radius and lift-off distance of the test coil and the conductivity of the material. An analytical expression is derived for the change in impedance as a function of the electric fields at the position of the flaw. It is found to be an integral over the volume of the flaw of the electric fields found with and without the flaw being present. The limiting case of a degenerate point flaw may be examined in greater detail by allowing the field in the presence of the flaw to be approximated by the unperturbed field. For flaws small enough that the field does not vary much over its volume, the field may be even further approximated by using just the value of the field at the position of the centroid of the flaw. Plots are shown to illustrate the behavior of the change in impedance as a function of the radial range of the flaw and the depth of the flaw centroid, using previously derived expressions for the fields for the unflawed case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566953
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Electromagnetic acoustic transducer for in-plane and plane-normal velocity measurements (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 85-91 
    Details
    ISSN: 1573-4862
    Keywords: displacement-field ; acoustic radiation ; wave propagation ; absolute velocity ; EMAT ; mode selective ; nonresonant frequency response ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A new electromagnetic acoustic transducer (EMAT) is developed that measures velocities and absolute surface displacements in-plane and plane-normal to the direction of wave propagation. This transducer is flexible in shape and design to conform with irregular surfaces and has unique characteristics of nonresonant frequency response. Tests show that the sensitivity of this EMAT can be increased by increasing the applied magnetic field. Because this transducer is mode selective and nonresonent, its response can be related uniquely to the wave motion. This property is highly desirable for research purposes, though generally not wanted in field monitoring situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568964
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Two-dimensional radiographic imaging analysis (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 221-227 
    Details
    ISSN: 1573-4862
    Keywords: Radiography ; point-spread function ; corner location ; edge location ; unsharpness ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Two-dimensional imaging properties of locally isotropic and isoplanatic point spread functions are described in a general radiographic context. In particular, the radiographic response to a two-dimensional wedge-shaped object is shown to possess several properties which enable the identification of the wedge corner on the image, thereby alleviating the need for image enhancement techniques. Extensions to the location of flat-edged boundaries are also discussed. The potential dimensioning application of this analysis lies in the precise and objective location of points of interest on radiographs of more complex two-dimensional objects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565866
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Loss of specular reflection due to nonlinear crack-face interaction (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 229-239 
    Details
    ISSN: 1573-4862
    Keywords: Crack-opening displacement ; crack closure ; ultrasonics ; Kirchoff approximation ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The interaction between rough crack faces is modeled by nonlinear relations between the crack-face tractions and the crack-opening displacements. These relations account for crack closure and for the related resistance to crack-face sliding. The relations are used to investigate reflection and transmission of an incident pulse by an infinite flaw plane. The problem statement is reduced to a set of inhomogeneous nonlinear ordinary differential equations for the displacement discontinuities, [u] and [v], across the flaw plane. These equations have been solved numerically. The reflection and transmission of an incident pulse by a crack with interacting crack faces. Both incident longitudinal and transverse waves have been considered. The loss of specular reflection as compared to a perfect (traction-free) crack is exhibited by specific examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565867
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Acoustoelastic response of polycrystalline aggregates exhibiting transverse isotropy (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 1-8 
    Details
    ISSN: 1573-4862
    Keywords: acoustoelasticity ; transverse isotropy ; polycrystalline aggregate ; cubic crystal ; third-order elastic constants ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Acoustoelasticity is an ultrasonic technique which has been used for the determination of active and residual stresses in common structural materials. This paper examines the effect of texture on the acoustoelastic response in polycrystalline bodies. In particular materials which are transversely isotropic aggregates of cubic crystals are studied. The second- and third-order elastic constants of the polycrystal are derived from the elastic properties of the constituent crystals, and the crystalline orientation relative to the body's symmetry axis. The acoustoelastic relations between velocity and deformation are then presented for the aggregate. Finally, evaluation of the acoustoelastic response for several ideal textures using data for aluminum single crystals shows that the response is highly dependent on the texture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566949
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...