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
Collection
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    A New Global Optimization Algorithm and its Application (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1407-1412 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In geotechnical engineering, based on the theory of inverse analysis of displacement, theproblem for identification of material parameters can be transformed into an optimization problem.Commonly, because of the non-linear relationship between the identified parameters and thedisplacement, the objective function bears the multimodal characteristic in the variable space. So tosolve better the multimodal characteristic in the non-linear inverse analysis, a new globaloptimization algorithm, which integrates the dynamic descent algorithm and the modified BFGS(Brogden-Fletcher-Goldfrab-Shanno) algorithm, is proposed. Five typical multimodal functions inthe variable space are tested to prove that the new proposed algorithm can quickly converge to thebest point with few function evaluations. In the practical application, the new algorithm is employedto identify the Young’s modulus of four different materials. The results of the identification furthershow that the new proposed algorithm is a very highly efficient and robust one
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1407.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A New Optimization Algorithm for Inverse Analysis to Material Parameters (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 1013-1019 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: the inverse analysis to material parameters is often translated into an optimization for anobjective function, based on the correlation between the material parameters and the foregoneinformation. But mostly because of the non-linear correlation, a good optimization algorithm withthe capabilities to avoid being trapped by local optima is required during the process ofoptimization. So the present paper proposes a new global optimization algorithm, which couples thedynamic canonical descent algorithm and the improved Powell’s algorithm. The high efficiency ofthe new algorithm is shown on four known problems classically for testing optimization algorithmsand finally, in the non-linear inverse analysis, the new algorithm is used for optimizing an objectivefunction to get material parameters rightly
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.575-578.1013.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Transformation using in vivo and in vitro methylation in Streptomyces griseus (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 209 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Streptomyces griseus does not readily take up foreign DNA isolated from other Streptomyces species or Escherichia coli, presumably due to its unique restriction-modification systems that function as a barrier for interspecific DNA transfer. To efficiently transform S. griseus by avoiding the restriction barriers, we methylated incoming DNA in vivo and in vitro and treated protoplasts with heat prior to transformation. Whereas heat treatment of protoplasts or methylation of the E. coli-Streptomyces shuttle vectors (pXE4 and pKK1443) did not prominently improve the transformation efficiency, HpaII methylation of the vectors from any E. coli strains tested in this study highly increased the transformation efficiency. The highest transformation efficiency was observed when the shuttle vectors were isolated from the dam, hsd strain of E. coli (GM161) and methylated by AluI and HpaII methyltransferases, and the efficiency was approximately the same as that of the vectors from S. griseus. We identified several restriction-modification systems that decrease the transformation efficiency. This research also led us to understand methylation profiles and restriction-modification systems in S. griseus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb11138.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Cloning and characterization of the gene encoding penicillin-binding protein A of Streptomyces griseus (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 193 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An internal segment of the penicillin-binding protein gene, pbpA, of Streptomyces griseus was amplified from genomic DNA using the polymerase chain reaction and used as a hybridization probe to isolate the complete gene from a cosmid library. pbpA encodes a 485 amino acid sequence that conserves three motifs of PBPs, SXXK, SXN, and KTG. The pbpA gene was located downstream of a gene homologous to the Bacillus subtilis spoVE gene. The pbpA gene was disrupted by replacing an ApaI fragment of the pbpA gene in S. griseus chromosome with an apramycin resistance gene cassette or directly inserting this apramycin resistance gene cassette at the NcoI site of pbpA penicillin-binding domain. No obvious defects in growth, sporulation, or spore sonication resistance were observed in the constructed pbpA mutants, suggesting that PBPA is not essential for growth and sporulation under normal laboratory conditions in S. griseus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09403.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Fluid dynamics and dust growth in plasma enhanced chemical vapor deposition (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1629-1631 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A paradox arises with the observation of large dust particles in a low-pressure plasma enhanced chemical vapor deposition reactor. Neutral drag forces in an axisymmetric flowing afterglow reactor permit micrometer sized dust grains to form by trapping them for long times in regions with high concentrations of film precursors. A summary of the relevant mechanical and electrostatic forces on dust grains shows that collisions with neutral gas reconcile the growth rate, residence times, and relatively large diameters of the observed dust particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111860
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    High-performance aromatic polyimide fibres (1996)
    Springer
    Journal of materials science 31 (1996), S. 4423-4431 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new polyimide has been synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 2,2′-dimethyl-4,4′-diaminobiphenyl (DMB). A high-strength, high-modulus, high-temperature fibre has been developed from this polyimide via a dry-jet wet spinning method. The tensile strength of BPDA-DMB fibres is 3.3 GPa and the tensile modulus is around 130 GPa. The compressive strength of the fibres has been investigated through a tensile recoil test (TRT), while the fibre morphology after compression has been studied via polarized light microscopy (PLM) and scanning electron microscopy (SEM). From the TRT measurements, we have observed that the compressive strength of this fibre is 665 (±5) MPa, which is higher than those of other aromatic polymer fibres. The effect of fibre diameter on the compressive strength of BPDA-DMB fibres is not substantial. The critical compressive strain for this fibre at which the kink bands start appearing under the observation of PLM is at 0.51–0.54%. Subglass relaxation processes have been observed and the measure of an apparent relaxation strength may serve as one of the factors which significantly affect the compressive strength of the fibres. Tensile tests of pre-compressed fibres reveal a continuous loss in tensile strength (up to 30%) with increasing the compressive strain (up to 2.6%). PLM and SEM observations show that during the compression BPDA-DMB fibres form regularly-spaced kink bands at ±60 ° (±2 °) with respect to the fibre axis. The kink band density initially increases with the compressive strain, and reaches a maximum at around 1.1%. Further increase of the compressive strain decreases this density due to the merge of the neighbouring bands. The size of kink bands also correspondingly increases within this compressive strain region. The morphological observation via SEM implies the existence of a skin-core structure and microfibrillar texture which are common features in polymer fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00356470
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Compressive properties of single-filament carbon fibres (1993)
    Springer
    Journal of materials science 28 (1993), S. 1611-1616 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Compressive properties of mesophase pitch-based carbon fibres (NT-20, NT-40 and NT-60) were measured using the tensile recoil test and the elastica loop test. The NT-40 fibre with a 400 GPa tensile modulus showed a smaller loop compressive yield strain and a larger recoil compressive strength compared to these values obtained from the longitudinal compression test on its unidirectional composites. Further, the recoil compressive strength of this fibre was higher than that of PAN-based carbon fibre with a corresponding modulus. Under the ideal conditions in the tensile recoil test, the strain energy was conserved before and after recoil, and the initial tensile stress and the recoil compressive stress do not coincide when fibre stress-strain behaviour is non-linear, and the non-linearity in compression and in tension is different. The difference between the composite compressive strength and the recoil compressive strength of NT-40 was quantitatively explained by taking account of the fibre compressive stress-strain non-linear relation. The difference between the loop compressive yield strain and the composite compressive strain to failure was also explained by this non-linearity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363356
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Characterization of chitosan and rare-earth-metal-ion doped chitosan films (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 1561-1578 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic study has been made on the influence of doped rare-earth metal ions (Er3+ and Nd3+) on the molecular interaction present in thin films fabricated from chitosan-acetic acid solutions (chitosan/HAc). FT-IR spectroscopy (including NIR, MIR and FIR) coupled with X-ray photoelectron spectroscopy (XPS) indicate a weak complexation between the metal ions and amine groups of chitosan. Specifically, the FIR spectra show broad bands near 550, 480 and 250 cm-1 for the doped films suggestive of metal ion-ligand vibrations. XPS indicates multiple chemical states of N with an increased percentage of a higher binding energy state nitrogen caused by a weak interaction with the doped metal ions. Slight differences in microroughness between the doped and undoped films as observed by X-ray reflectometry may also be related to the doping. The NIR and MIR spectra do not show any significant changes for all the doped and undoped films, implying that the basic molecular conformation of chitosan is not changed by the weak complexation.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980519
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Internal stress, lattice deformation, and modulus of polymers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1779-1791 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The relationships among internal stress, lattice deformation, and the moduli of polymers, such as poly(ethylene terephthalate) (PET), polypropylene (PP), polyethylene (PE), polyacryonitrile (PAN), and poly(p-phenylene terephthalamide) (PPTA), have been studied systematically. Compared to small molecule crystals, polymer crystals have many more defects and their parameters of the crystal unit cells and the density of the crystalline region are easy to vary to a certain extent. During the processing, external stresses were put on the polymer fibers and polymer molecules were drastically deformed, which induced polymer crystallization and preferred orientation. After processing, there are many macromolecules frozen in the nonequilibrium status, which is the cause of internal stress. Heat treatment could give energy to the macromolecules to release the internal stress and to approach thermodynamic equilibrium. For polymer crystals, the higher the annealing temperature, the shorter the lengths of the unit cell axes, the more integral and regular the crystal lattice, and the smaller the unit cell volume. Crystalline modulus changes not only with different kinds of polymer materials, but also with measurement temperature and processing history. Polymer processing, mainly drawing, causes orientation and internal stress which causes lattice deformation and raises tensile modulus of polymer materials.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420635
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Optical waveguiding and morphology of chitosan thin films (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1163-1171 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An investigation was made of the optical and waveguiding properties of thin films fabricated from solutions of chitosan-acetic acid (chitosan/HAc) and chitosan/HAc doped with rare-earth metal ions (Er+++ or Nd+++). For all three films, the refractive indices were approximately 1.5 and there was nearly no absorption in the range of 300 to 2700 nm. The optical loss in a waveguides was less than 0.5 dB/cm. Morphological observations disclosed that all the films possessed a dense and homogeneous amorphous structure with smooth surfaces. Extrinsic scattering, especially the scattering caused by surface impurities, was the dominating factor affecting the optical loss value. It is also interesting to note that for all the films, doped with rare-earth metal ions or not, the morphological characteristics were alike and the optical properties were similar. Doping rare-earth metal ions into chitosan thin films did not seriously influence optical waveguiding. This paper reports, we believe, the first study of chitosan films for optical applications. The experimental results demonstrate that chitosan and its derivatives are potential candidates for optical materials. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...