ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 71 (1988), S. 187-198 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents For synchronous machines based on permanent magnet excitation and the transvers flux concept an analytical approach for field and force calculations is being described. One of the assumptions is a known trapezoidal wave form of the armature current, maintained by appropriate frequency inverter and terminal voltage. The analysis covers one and two-sided armature configurations as well as different configurations of the excitation (magnet) system of the rotor. Refinements of the analysis can be achieved by taking into account magnetic leakage components and saturation effects. Comparisons with the 3-dimensional FE-computation and with results from measurements are presented.
    Notes: Übersicht Ausgehend von der Transversalfluß-Anordnung des magnetischen Kreises wird für permanentmagneterregte Synchronmaschinen die Berechnungsmethode beschrieben. Hierbei ist vorausgesetzt, daß durch Wechselrichterspeisung die Stromform näherungsweise trapezförmig vorgegeben ist. Für ein- und zweiseitige Statoranordnungen sowie Erregersysteme in Flachmagnet- und Sammlerkonfiguration werden die mathematischen Beziehungen zwischen Feld- und Stromgrößen und den Abmessungsparametern angegeben. Es wird auf verschiedene Verfeinerungsstufen des Berechnungsverfahrens, etwa durch Berücksichtigung von Streuflußkomponenten und Sättigung des Eisenwegs, hingewiesen. Vergleiche mit der dreidimensionalen FE-Methode und mit Messungen an einem Modellmotor beschließen die Arbeit.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 20 (1995), S. 84-90 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The paper presents the results of an investigation on the motion of a spherical particle in a shock tube flow. A shock tube facility was used for studying the acceleration of a sphere by an incident shock wave. Using different optical methods and performing experiments in two different shock tubes, the trajectory and velocity of a spherical particle were measured. Based upon these results and simple one-dimensional calculations, the drag coefficient of a sphere and shading effect of sphere interaction with a shock tube flow were studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The paper describes new experimental results regarding the pressure fields in front of and inside granular layers of different materials during their collision with weak shock waves. A variety of waves result from the shock wave-granular layer interaction. The pressure behind the reflected wave from the material interface approaches the equilibrium value, P 5, which would have been reached had the shock wave reflected from a solid end-wall. The wave succession inside the layer depends solely on two processes: the complex interaction of the compaction wave with the granular material and the gas filtration, which affects the particles by the drag forces between the two phases. Inside a material with a permeability coefficient f〉0.001 mm2 the transmitted wave moves with a constant velocity which is largely governed by the gas filtration. For low permeability materials ( f〈0.0003 mm2) the transmitted wave trajectory strongly depends on the compaction wave propagation. In such cases the compaction wave was found to be unsteady and its acceleration was higher in material having low material densities. The maximum compressive stress values, P c , reached at the shock tube end-wall, covered by the materials under investigation, manifested as an unsteady pressure peak twice as large as the gas pressure P 5, measured ahead of the layer. Comparing the present data with those available in the literature showed that the amplitude of the unsteady pressure peak was higher in materials having low effective densities, γ, and small permeability coefficients f. Contrary to flexible foams where the available experimental data indicated that the compressive stress in the post peak period converges to P 5=P g , the results obtained in the present study indicated that during the test time the compressive stress, P s , was well preserved in the material and for most of the sample length its value was within the range P s 〉P 5〉P g .
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Certain aspects of wave propagation and the dynamic reaction of a granular material when subjected to a long-duration impulse load are studied. In the majority of studies published on this subject the unsteady pressure behavior at the end-wall covered by a layer of granular material was observed and documented. However, up to now little attention was given to explaining the physical mechanism of this process. Experimental results, obtained in the course of this study, regarding the pressure fields inside granular layers of different materials, clearly show that the compaction effect strongly depends on the characteristics of the medium. This phenomenon manifests itself by changing the gas-particle interaction in the course of the gas filtration, and by variation in the contribution of the different forces and effective stress, σ, to the energy exchange between the gas, the particles and the shock-tube wall. The material permeability,  f, the relative density, ν, and the particle response time, τ p , are the most important parameters affecting the stress formation at the end-wall covered by the granular layer. In addition to the effect of the material parameters, the effective stress, σ, was found to strongly depend on the granular layer height, h. Based on detailed pressure measurements a qualitative analysis regarding the role of the particle rearrangement in the formation of the unsteady peak at the end-wall was performed. The phenomenology of the particle–particle interaction includes rotation and consolidation of the granules and movement or sliding of particle planes within the layer over each other. Most of these processes are frictional in their nature. They are related to the energy losses and affect the profile and magnitude of the compressive stress as measured at the shock-tube end-wall covered by the granular layer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 9 (1998), S. 275-278 
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Nano-sized xSnO2-(1–xα-Fe2O3 materials have been prepared using the high energy ball milling technique and their structural and gas sensing properties have been characterized. Based on experimental results, we propose a new structure model, □1/3→Sn4+1/3+2(1–y) O2-s+4yO-s, for these non-equilibrium, nano-sized xSnO2-(1–x)α-Fe2O3 materials. This model can explain not only the lattice expansion of the milled samples, but also takes into account the charge balance by adding oxygen dangling bonds at the particle surfaces, which can be visualized in the nano-sized powders. The thick film gas sensors made by such mechanically alloyed materials have high ethanol gas sensitivity values of 289 in air and 1016 in nitrogen at 1000 p.p.m. and very good gas selectivity to ethanol over CO and H2 gases. It is believed that the high ethanol gas sensitivity of these materials is related to the enormous defects such as O- and O2- dangling bonds at the particle surfaces of these nano-sized materials. © 1998 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    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 Al2O3 fibre-hexagonal BN particle hybrid reinforced aluminium-silicon alloys were fabricated by centrifugal force infiltration route. Hardness test and ultimate compressive test results are reported. The wear and friction properties of hybrid MMCs was investigated by means of a block-on-ring (bearing steel) type wear rig in a dry sliding condition. It is shown that the hardness and ultimate compressive strength of hybrid MMCs was evidently decreased with the addition of hexagonal BN particles, however, the wear rate and coefficient of friction of hybrid MMCs was improved simultaneously with increase of BN particle volume fraction, especially for the higher applied loads in the test.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 23 (1996), S. 273-281 
    ISSN: 1432-0789
    Keywords: Key words Wheat ; (Triticum aestivum) ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20NE ; Flavobacterium spp. ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson‘s test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 20 (1995), S. 84-90 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The paper presents the results of an investigation on the motion of a spherical particle in a shock tube flow. A shock tube facility was used for studying the acceleration of a sphere by an incident shock wave. Using different optical methods and performing experiments in two different shock tubes, the trajectory and velocity of a spherical particle were measured. Based upon these results and simple one-dimensional calculations, the drag coefficient of a sphere and shading effect of sphere interaction with a shock tube flow were studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1617-4623
    Keywords: Key words Fluorescence in situ hybridization (FISH) ; Interphase mapping ; Physical mapping ; Maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The chromatin in interphase nuclei is much less condensed than are metaphase chromosomes, making the resolving power of fluorescence in situ hybridization (FISH) two orders of magnitude higher in interphase nuclei than on metaphase chromosomes. In mammalian species it has been demonstrated that within a certain range the interphase distance between two FISH sites can be used to estimate the linear DNA distance between the two probes. The interphase mapping strategy has never been applied in plant species, mainly because of the low sensitivity of the FISH technique on plant chromosomes. Using a CCD (charge-coupled device) camera system, we demonstrate that DNA probes in the 4 to 8 kb range can be detected on both metaphase and interphase chromosomes in maize. DNA probes pA1-Lc and pSh2.5⋅SstISalI, which contain the maize loci a1 and sh2, respectively, and are separated by 140 kb, completely overlapped on metaphase chromosomes. However, when the two probes were mapped in interphase nuclei, the FISH signals were well separated from each other in 86% of the FISH sites analyzed. The average interphase distance between the two probes was 0.50 μm. This result suggests that the resolving power of interphase FISH mapping in plant species can be as little as 100 kb. We also mapped the interphase locations of another pair of probes, ksu3/4 and ksu16, which span the Rp1 complex controlling rust resistance of maize. Probes ksu3/4 and ksu16 were mapped genetically approximately 4 cM apart and their FISH signals were also overlapped on metaphase chromosomes. These two probes were separated by an average of 2.32 μm in interphase nuclei. The possibility of estimating the linear DNA distance between ksu3/4 and ksu16 is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1617-4623
    Keywords: Fluorescence in situ hybridization (FISH) ; Interphase mapping ; Physical mapping ; Maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromatin in interphase nuclei is much less condensed than are metaphase chromosomes, making the resolving power of fluorescence in situ hybridization (FISH) two orders of magnitude higher in interphase nuclei than on metaphase chromosomes. In mammalian species it has been demonstrated that within a certain range the interphase distance between two FISH sites can be used to estimate the linear DNA distance between the two probes. The intephase mapping strategy has never been applied in plant species, mainly because of the low sensitivity of the FISH technique on plant chromosomes. Using a CCD (charge-coupled device) camera system, we demonstrate that DNA probes in the 4 to 8 kb range can be detected on both metaphase and interphase chromosomes in maize. DNA probes pA1-Lc and pSh2.5·SstISalI, which contain the maize locia1 andsh2, respectively, and are separated by 140 kb, completely overlapped on metaphase chromosomes. However, when the two probes were mapped in interphase nuclei, the FISH signals were well separated from each other in 86% of the FISH sites analyzed. The average interphase distance between the two probes was 0.50 µm. This result suggests that the resolving power of interphase FISH mapping in plant species can be as little as 100 kb. We also mapped the interphase locations of another pair of probes, ksu3/4 and ksu16, which span theRp1 complex controlling rust resistance of maize. Probes ksu3/4 and ksu16 were mapped genetically approximately 4 cM apart and their FISH signals were also overlapped on metaphase chromosomes. These two probes were separated by an average of 2.32 µm in interphase nuclei. The possibility of estimating the linear DNA distance between ksu3/4 and ksu16 is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...