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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 125 (1993), S. 217-256 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract In this paper we study the asymptotic nonlinear stability of discrete shocks for the Lax-Friedrichs scheme for approximating general m×m systems of nonlinear hyperbolic conservation laws. It is shown that weak single discrete shocks for such a scheme are nonlinearly stable in the L p-norm for all p ≧ 1, provided that the sums of the initial perturbations equal zero. These results should shed light on the convergence of the numerical solution constructed by the Lax-Friedrichs scheme for the single-shock solution of system of hyperbolic conservation laws. If the Riemann solution corresponding to the given far-field states is a superposition of m single shocks from each characteristic family, we show that the corresponding multiple discrete shocks are nonlinearly stable in L p (P ≧ 2). These results are proved by using both a weighted estimate and a characteristic energy method based on the internal structures of the discrete shocks and the essential monotonicity of the Lax-Friedrichs scheme.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 135 (1996), S. 61-105 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract In this paper, we study the fluid-dynamic limit for the one-dimensional Broadwell model of the nonlinear Boltzmann equation in the presence of boundaries. We consider an analogue of Maxwell's diffusive and reflective boundary conditions. The boundary layers can be classified as either compressive or expansive in terms of the associated characteristic fields. We show that both expansive and compressive boundary layers (before detachment) are nonlinearly stable and that the layer effects are localized so that the fluid dynamic approximation is valid away from the boundary. We also show that the same conclusion holds for short time without the structural conditions on the boundary layers. A rigorous estimate for the distance between the kinetic solution and the fluid-dynamic solution in terms of the mean-free path in theL ∞-norm is obtained provided that the interior fluid flow is smooth. The rate of convergence is optimal.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 135 (1996), S. 61-105 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: In this paper, we study the fluid-dynamic limit for the one-dimensional Broadwell model of the nonlinear Boltzmann equation in the presence of boundaries. We consider an analogue of Maxwell's diffusive and reflective boundary conditions. The boundary layers can be classified as either compressive or expansive in terms of the associated characteristic fields. We show that both expansive and compressive boundary layers (before detachment) are nonlinearly stable and that the layer effects are localized so that the fluid dynamic approximation is valid away from the boundary. We also show that the same conclusion holds for short time without the structural conditions on the boundary layers. A rigorous estimate for the distance between the kinetic solution and the fluid-dynamic solution in terms of the mean-free path in the L y -norm is obtained provided that the interior fluid flow is smooth. The rate of convergence is optimal.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica solida Sinica 1 (1988), S. 149-158 
    ISSN: 0894-9166
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In the present paper, the new material parameter of ductile fracturev gc with an obvious microscopic physical meaning is emphasized, which can be determined by macroscopic method. The theoretical and experimental background for the criterion of critical void growth ratio is expounded from both macroscopic and microscopic points of view. The relationship between the macroform parameterv gc and microform oneR c /R go of critical void growth ratio is investigated. The engineering experimental procedure for determining the value ofv gc of materials has been recommended. The values ofv gc for some materials with different heat treatments have been estimated. It is found that the parameterv gc can be effectively used for selecting materials and their heat treatments. A modified ASPEF criterion accounting for stress states has been proposed. Related expression of modified ASPEF andv gc has been derived.
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  • 5
    ISSN: 1572-9001
    Keywords: Vibrational spectra ; structural parameters ; r 0 geometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The far-infrared spectrum of gaseous fluoromethyl methyl ether, FCH2OCH3, along with three of the deuterium isotopes, has been recorded at a resolution of 0.10 cm−1 in the 350 to 50 cm−1 region. The fundamental asymmetric torsional and methyl torsional modes are extensively mixed and have been observed at 182 and 132 cm−1, respectively, for the stablegauche conformer with the lower frequency band having several excited states falling to lower frequency. An estimate is given for the potential function governing the asymmetric rotation. On the basis of a one-dimensional model the barrier to internal rotation of the methyl moiety is determined to be 527±9 cm−1 (1.51±0.03 kcal/mol). A complete assignment of the vibrational fundamentals for all four isotopic species observed from the infrared (3500 to 50 cm−1) spectra of the gas and solid and from the Raman (3200 to 10 cm−1) spectra of the gas, liquid, and solid is proposed. No evidence could be found in any of the spectra for the high-energytrans conformer. All of these data are compared to the corresponding quantities obtained from ab initio Hartree-Fock gradient calculations employing the 3-21G and 6-31G* basis sets along with the 6-31G* basis set with electron correlation at the MP2 level. Additionally, completer 0 geometries have been determined from the previously reported microwave data and carbon-hydrogen distances determined from infrared studies. The heavy-atom structural parameters (distances in Å, angles in degrees) arer(C1-F) = 1.395 ± 0.005;r(C1-O) = 1.368 ± 0.007;r(C2-O) = 1.426 ±0.003; ⦔FC1O = 111.33 ± 0.25; ⦔C1OC2 = 113.50 ± 0.18 and dih FC1OC2 = 69.12 ± 0.26. All of these results are discussed and compared with the corresponding quantities obtained for some similar molecules.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Natural resources research 9 (2000), S. 269-276 
    ISSN: 1573-8981
    Keywords: ETM+ ; fusion ; spectral preserve ; spatial improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Landsat-7 ETM+ panchromatic band is taken simultaneously with multispectral bands using the same sensor system. The two data sets, therefore, are coregistered accurately and the solar illumination and other environmental conditions are identical. This makes ETM+ Pan advantageous to SPOT Pan for resolution fusion. A spectral preserve image fusion technique, Smoothing Filter-Based Intensity Modulation (SFIM), can produce optimal fusion data without altering the spectral properties of the original image if the coregistration error is minimal. With TM/SPOT Pan fusion, the technique is superior to HSI and Brovey transform fusion techniques in spectral fidelity, but has slightly degraded edge sharpness as a result of TM/SPOT Pan coregistration error because SFIM is sensitive to coregistration accuracy and temporal changes of edges. The problem is self-resolved for ETM+ because there is virtually no coregistration error between the panchromatic band and the multispectral bands. Quality fusion imagery data thus can be produced.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of electronic testing 16 (2000), S. 499-511 
    ISSN: 1573-0727
    Keywords: transient power supply current (i DDT) ; transient current sensor ; disturb fault ; CMOS SRAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract We describe the design and implementation of a dynamic power supply current sensor which is used to detect SRAM faults such as disturb faults as well as logic cell faults. A formal study is presented to assess the parameters that influence the sensor design. The sensor detects faults by detecting abnormal levels of the power supply current. The sensor is embedded in the SRAM and offers on-chip detectability of faults. The sensor detects abnormal dynamic current levels that result from circuit defects. If two or more memory cells erroneously switch as a result of a write or read operation, the level of the dynamic power supply current is elevated. The sensor can detect this elevated value of the dynamic current. The dynamic power supply current sensor can supplement the observability associated with any test algorithm by using the sensor as a substitute for the read operations. This significantly reduces the test length and the additional observability enhances defect coverages.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 57 (1984), S. 85-90 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of the existence of absorbing atoms in a laser cavity on the critical exponents of abrupt transitions between steady states in the system of single mode onephoton laser driven by an external coherent field is discussed. An isolated threshold when $$\bar \sigma = \bar \sigma _0 ,\bar \sigma = - \kappa \bar \gamma _ \bot S/\bar N|\bar g|^2 (\bar S - S)$$ ,and a kind of threshold when , where $$\bar \sigma $$ is the pump parameter of the absorbing atoms, is obtained. The asymptotic forms of the families of potential functions for the system near these threshold are also found. The well-known scaling hypothesis in the general homogeneous function form is shown to be a characteristic of these asymptotic families. Four threshold exponents, β, δ, γ′ and α′ and four threshold amplitudes,B, D, Γ′ andA′, near each of these thresholds, are obtained. The threshold exponents near each threshold obey the scaling laws of critical phenomena, while the corresponding amplitudes obey the definite relations between exponents and amplitudes.
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  • 10
    ISSN: 1435-0157
    Keywords: Key words groundwater/surface-water relations ; karst ; groundwater management ; artificial recharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé Le champ captant de Dawu, l'un des plus importants de Chine, fournit l'essentiel de l'eau à la communauté urbaine de Zibo, dans la province de Shandong. Ce champ captant fournit entre 522,400 et 535,400 m3/j à partir d'un aquifère fracturé karstique des carbonates de l'Ordovicien moyen. La plupart de la recharge de cet aquifère est assurée par des pertes d'eau de surface de la rivière Zihe, principal cours d'eau de la région. La mise en eau du réservoir de Taihe en 1972 a sévèrement réduit en aval l'écoulement de la Zihe, ce qui a provoqué une diminution nette du niveau de la nappe dans le champ captant de Dawu. Depuis 1974, après la mise en fonctionnement d'une station de recharge sur la rivière Zihe, injectant, en amont du champ captant, de l'eau du réservoir de Taihe dans la rivière, les ressources en eau souterraine ont été reconstituées. Par ailleurs, en moyenne 61,200 m3/j d'eau souterraine, principalement de l'aquifère ordovicien, sont pompés dans la mine de fer de Heiwang, un puits ouvert dans le lit de la rivière Zihe, sous le réservoir de Taihe. Une équation de régression par étape, utilisée pour évaluer le rôle du débit fourni par le réservoir à la rivière, confirme que l'eau du réservoir est l'une des plus importantes sources d'eau souterraine dans la mine.
    Notes: Abstract  The Dawu well field, one of the largest in China, supplies most of the water for the Zibo City urban area in Shandong Province. The field yields 522,400–535,400 m3/d from an aquifer in fractured karstic Middle Ordovician carbonate rocks. Much of the recharge to the aquifer is leakage of surface water from Zihe Stream, the major drainage in the area. Installation of the Taihe Reservoir in 1972 severely reduced the downstream flow in Zihe Stream, resulting in a marked reduction in the water table in the Dawu field. Since 1994, following the installation of a recharge station on Zihe Stream upstream from the well field that injects water from the Taihe Reservoir into the stream, the groundwater resources of the field have recovered. An average of 61.2×103 m3/d of groundwater, mostly from the Ordovician aquifer, is pumped from the Heiwang iron mine, an open pit in the bed of Zihe Stream below the Taihe Reservoir. A stepwise regression equation, used to evaluate the role of discharge from the reservoir into the stream, confirms that reservoir water is one of the major sources of groundwater in the mine.
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