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91.
Svetlana M. Zen��kovskaya Vasiliy A. Novosiadliy 《Journal of Engineering Mathematics》2011,69(2-3):277-289
A scheme for applying an averaging method to the problem of convection in a two-layer system with an interface under the influence of high-frequency vibration is proposed. The derivation of the averaging equations is given, and the stability of the equilibrium of the averaged problem is considered. Long-wavelength asymptotics of steady and oscillatory instability are constructed. The results of numerical calculations for acetonitrile?Cn-hexane and silicone oil?Cfluorinert systems are given. The directions in which the investigation of thermovibrational convection in problems with free surfaces and interfaces can be continued, are indicated. 相似文献
92.
Matthias M. M��ller Harald R. Haakh Tommaso Calarco Christiane P. Koch Carsten Henkel 《Quantum Information Processing》2011,10(6):771-792
Atom chips are a promising candidate for a scalable architecture for quantum information processing provided a universal set
of gates can be implemented with high fidelity. The difficult part in achieving universality is the entangling two-qubit gate.
We consider a Rydberg phase gate for two atoms trapped on a chip and employ optimal control theory to find the shortest gate
that still yields a reasonable gate error. Our parameters correspond to a situation where the Rydberg blockade regime is not
yet reached. We discuss the role of spontaneous emission and the effect of noise from the chip surface on the atoms in the
Rydberg state. 相似文献
93.
A. A. D��az J. J. Rodr��guez-N��?ez A. A. Schmidt I. ?ifrea 《Journal of Superconductivity and Novel Magnetism》2011,24(7):2091-2098
We studied the possible superconducting state in an electronic itinerant ferromagnetic system characterized by a density of states that presents a moderately strong peak that is controlled by a specific parameter a and is positioned near the band edge. Specifically, we investigated the superconducting critical temperature, T c , and the zero-temperature superconducting gap, ??0. The analysis is done in a self-consistent way, the BCS mean-field equation being solved together with the electron density equation to trace possible changes in the system??s chemical potential due to the strong correlations between the component electrons. We discussed the density dependence of the superconducting critical temperature and zero-temperature superconducting gap for various values of the control parameter a and of the electron?Celectron attractive interaction. In the zero temperature limit we derive the system??s phase diagram and discuss the possible fermionic and bosonic regimes of the diagram as function of the strength of the attractive interaction. 相似文献
94.
Virginia E. Pitzer C��cile Viboud Ben A. Lopman Manish M. Patel Umesh D. Parashar Bryan T. Grenfell 《Journal of the Royal Society Interface》2011,8(64):1584-1593
Rotavirus is a major cause of mortality in developing countries, and yet the dynamics of rotavirus in such settings are poorly understood. Rotavirus is typically less seasonal in the tropics, although recent observational studies have challenged the universality of this pattern. While numerous studies have examined the association between environmental factors and rotavirus incidence, here we explore the role of intrinsic factors. By fitting a mathematical model of rotavirus transmission dynamics to published age distributions of cases from 15 countries, we obtain estimates of local transmission rates. Model-predicted patterns of seasonal incidence based solely on differences in birth rates and transmission rates are significantly correlated with those observed (Spearman''s ρ = 0.65, p < 0.05). We then examine seasonal patterns of rotavirus predicted across a range of different birth rates and transmission rates and explore how vaccination may impact these patterns. Our results suggest that the relative lack of rotavirus seasonality observed in many tropical countries may be due to the high birth rates and transmission rates typical of developing countries rather than being driven primarily by environmental conditions. While vaccination is expected to decrease the overall burden of disease, it may increase the degree of seasonal variation in the incidence of rotavirus in some settings. 相似文献
95.
96.
97.
We look at the well-known problem of allocating software components to compute resources (nodes) in a network, given resource
constraints on the infrastructure and the quality of service requirements of the components to be allocated to nodes. This
problem has many twists and angles, and has been studied extensively in the literature. Solving it is particularly problematic
when there is extensive dynamism and scale involved. Typically, heuristics are needed. 相似文献
98.
H. Schleifenbaum A. Diatlov C. Hinke J. B��ltmann H. Voswinckel 《Production Engineering》2011,5(4):359-371
World market competition currently boosts trends like mass customization and open innovation which result in a demand for
highly individualized products at costs matching or beating those of mass production. This work focus on the resolution of
the production related dilemma between scale and scope, e.g. either the low-cost production of high quantities or the high-end
and thus cost-intensive low-volume production of individualized goods. One of the areas of greatest potential for the resolution
of this dilemma are rapid manufacturing (RM) technologies due to their almost infinite geometrical variability and freedom
of design without the need for part-specific tooling. Selective Laser Melting (SLM) is one of the RM technologies that additionally
provides series identical mechanical properties without the need for downstream sintering processes, etc. However, the state-of-the-art
process and cost efficiency is not yet suited for series production. In order to improve this efficiency and enable SLM to
enter series production it is indispensable to increase the build rate significantly by means of increased laser power and
larger beam diameters. To exploit this potential, a new generation production machine including a kW laser and an optical
multi-beam system is developed and experimental results and real life components are shown. 相似文献
99.
Vojt��ch Kulvait Josef M��lek K. R. Rajagopal 《International Journal of Fracture》2013,179(1-2):59-73
The main purpose of this study is to investigate the efficacy and usefulness of a class of recently proposed models that could be reasonable candidates for describing the response of brittle elastic materials. The class of models that are considered allows for a non-linear relationship between the linearized elastic strain and the Cauchy stress, and this allows one to describe situations wherein the stress increases while the strain yet remains small. Thus one would be in a position to model the response of brittle elastic bodies in the neighborhood of the tips of cracks and notches. In this paper we study the behavior of such models in a plate with a V-notch subject to a state of anti-plane stress. This geometrical simplification enables us to characterize the governing equation for the problem by means of the Airy stress function, though the constitutive relation is a non-linear relation between the linearized strain and the stress. We study the problem numerically by appealing to the finite element method. We find that the numerical solutions are stable. We are able to provide some information regarding the nature of the solution near the tip of the V-notch. In particular we find stress concentration in the vicinity of the singularity. 相似文献
100.
Nearly all soft tissues, including the vascular tissue, present a certain degree of viscoelastic material response, which becomes apparent performing multiple relaxation tests over a wide range of strain levels and plotting the resulting stress relaxation curves, nonlinear viscoelasticity of the tissue. Changes in relaxation rate at each strain may occur at multiple strain levels. A constitutive formulation considering the particular features of the vascular tissue, such as anisotropy, together with these nonlinear viscoelastic phenomena is here presented and used to fit stress?Cstretch curves from experimental relaxation tests. This constitutive model was used to fit several data set of in vitro experimental stress relaxation tests performed on ovine and porcine aorta. The good fitting of the experimental data shows the capability of the model to reproduce the viscoelastic response of the vascular tissue. 相似文献