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11.
Ulrich Buchenau 《Journal of Low Temperature Physics》2004,137(3-4):345-353
A recent hypothesis claims that the glass transition itself, though it is a very pronounced relaxation peak, is no separate relaxation process at all, but is just the breakdown of the shear modulus due to the weak elastic dipole interaction between all the quasi-independent relaxation centers of the glass. Two derivations are considered, one of them in terms of a breakdown of the shear modulus and the second in terms of a divergence of the shear compliance. Mechanical relaxation data from the literature for vitreous silica, glycerol, polymethylmethacrylate and polystyrene are found to be consistent with the first hypothesis. PACS numbers: 64.70.Pf 相似文献
12.
Dirk Abendroth Martin E. Eckel Ulrich Killat 《AEUE-International Journal of Electronics and Communications》2006,60(5):404-407
In this article, we present two efficient weighted fair queueing (WFQ) scheduling algorithms leaned on the well-known token bucket and leaky bucket shaping/policing algorithms. The performance of the presented algorithms is compared to those of the state-of-the-art WFQ approximations such as weighted round robin (WRR) and the recently proposed bin sort fair queueing (BSFQ). Our simulation results show that the proposed algorithms provide a better fairness at a lower implementation complexity while simultaneously achieving a comparable network utilization. 相似文献
13.
A task-switching paradigm with a 2:1 mapping between cues and tasks was used to separate cue-switching processes (indexed through pure cue-switch costs) from actual task-switching processes (indexed through additional costs in case of cue and task changes). A large portion of total switch costs was due to cue changes (Experiments 1 and 2), and cue-switch costs but not task-switch costs were sensitive to effects of practice (Experiment 1) and preparation (Experiment 2). In contrast, task-switch costs were particularly sensitive to response-priming effects (Experiments 1 and 2) and task-set inhibition (Experiment 3). Results suggest two processing stages relevant during task-set selection: cue-driven retrieval of task rules from long-term memory and the automatic application of rules to a particular stimulus situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
Interfacial hybridization kinetics of oligonucleotides immobilized onto fused silica surfaces 总被引:3,自引:0,他引:3
Jiang Zeng Amer Almadidy James Watterson Ulrich J. Krull 《Sensors and actuators. B, Chemical》2003,90(1-3):68-75
Fused silica optical fibers have been used in an intrinsic mode optical configuration as biosensors for fluorescence based detection of hybridization of nucleic acids. In this work, the kinetics of hybridization of single-stranded oligonucleotides that were covalently immobilized were studied. The probe DNA was dT20, and the target was Fluorescein-labeled non-complementary (dT20) or complementary (dA20) oligonucleotide. Chronofluorimetric monitoring of the adsorption and hybridization processes was used to investigate oligonucleotide films of different density, in different salt concentrations, at temperatures of 25 and 40 °C, with the concentration of the target DNA being 0.005–0.1 μM. Mathematical models based on first- and second-order Langmuir adsorption have been examined to describe both the adsorption and the hybridization processes. Experimental data were processed using the models, and the hybridization kinetics were calculated. Hybridization kinetics on these optical fiber DNA sensors was found to be up to three orders faster than results presented for a number of other experiments using different immobilization chemistries. 相似文献
15.
16.
Petr A. Nikrityuk Kerstin Eckert Roger Grundmann 《Metallurgical and Materials Transactions B》2006,37(3):349-359
This paper presents a numerical study of the Lorentz force and fluid flow induced by a rotating magnetic field in a medium
with a nonhomogeneous electric conductivity placed in a cylindrical vessel with insulated walls. The nonhomogeneity is modeled
by the presence of a solid and a liquid phase of different electrical conductivity. The solid phase is located orthogonally
to the axis of rotation, which corresponds to the case of unidirectional solidification. The simulations were performed for
different locations of the solid front and different ratios of the electrical conductivity, σ
s
/σ
l
=0.2... 10. Here σ
s
and σ
l
are the electric conductivity of the solid and liquid phases, respectively. The results showed that the difference between
electrical conductivity of solid and liquid phases has a noticeable effect on the mean-time Lorentz force and the velocity:
namely, the presence of the solid phase (σ
s
>σ
l
) leads to an increase of the Lorentz force and fluid flow in the cylinder. 相似文献
17.
Charbel Farhat Ulrich Hetmaniuk 《International journal for numerical methods in engineering》2002,54(9):1309-1332
We present a fictitious domain decomposition method for the fast solution of high‐frequency acoustic scattering problems characterized by a partially axisymmetric sound‐soft scatterer. We apply this method to the solution of various mockup submarine problems, and highlight its computational advantages and intrinsic parallelism. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
18.
R. Grundmann 《Chemical Engineering and Processing: Process Intensification》1985,19(2):113-115
The pressure drop in helical coils can easily be calculated with good precision. The required friction factor λ can be taken from the friction diagram presented in this paper. The diagram also offers a graphic view of the pertinent parameters and the flow condition (laminar or turbulent) in the helically coiled tube. 相似文献
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