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排序方式: 共有143条查询结果,搜索用时 31 毫秒
1.
This paper proposes a perturbation-based heuristic for the capacitated multisource Weber problem. This procedure is based on an effective use of borderline customers. Several implementations are considered and the two most appropriate are then computationally enhanced by using a reduced neighbourhood when solving the transportation problem. Computational results are presented using data sets from the literature, originally used for the uncapacitated case, with encouraging results. 相似文献
2.
Caterina Calgaro Claire Colin Emmanuel Creus Ezzeddine Zahrouni 《Mathematical Methods in the Applied Sciences》2019,42(1):250-271
In this work, we prove the existence and the uniqueness of the strong solution of a low‐Mach model, for which the dynamic viscosity of the fluid is a given function of its temperature. The method is based on the convergence study of a sequence towards the solution, for which the rates are also given. The originality of the approach is to consider the system in terms of the temperature and the velocity, leading to a nonlinear temperature equation and the development of some specific tools and results. 相似文献
3.
4.
Jamil Salhi James MacLaurin Salwa Toumi 《Stochastics An International Journal of Probability and Stochastic Processes》2018,90(1):49-60
In this paper we obtain a time-uniform propagation estimate for a system of interacting diffusion processes. Using a well defined metric function h , our result guarantees a time-uniform estimate for the convergence of a class of interacting stochastic differential equations towards their mean field limit, under conditions that ensure that the decay associated to the internal dynamics term dominates the interaction and noise terms. Our result should have diverse applications, particularly in neuroscience, and allows for models more elaborate than the one of Wilson and Cowan. In particular, the internal dynamics need not be that of linear decay. 相似文献
5.
Well-known as a hazardous compound, nitrite constitute a real threat to the public health. So, there is a pressing need to detect and quantify them in different matrix. Even though conventional analytical methods can be used to address this issue, electrochemistry allows a fast, sensitive, and efficient analysis. Conducting polymers continue to raise great interest among scientific communities due to their properties. Moreover, their combination with carbon nanomaterials, or metallic nanoparticles improves their properties, and provides great results. In this paper, we will focus on some revealing works devoted to the electrochemical detection of nitrite using this kind of materials. 相似文献
6.
The concept of ‘nested methods’ is adopted to solve the location-routeing problem. Unlike the sequential and iterative approaches, in this method we treat the routeing element as a sub-problem within the larger problem of location. Efficient techniques that take into account the above concept and which use a neighbourhood structure inspired from computational geometry are presented. A simple version of tabu search is also embedded into our methods to improve the solutions further. Computational testing is carried out on five sets of problems of 400 customers with five levels of depot fixed costs, and the results obtained are encouraging. 相似文献
7.
B. Ortaç A. Hideur M. Brunel T. Chartier M. Salhi H. Leblond F. Sanchez 《Applied physics. B, Lasers and optics》2003,77(6-7):589-594
The properties of an ytterbium-doped double-clad fiber laser, passively mode-locked by nonlinear polarization rotation are investigated in this work. Cartographies of mode-locking regime versus halfwave plates orientations are presented for several values of the total cavity dispersion and for different pump powers. Bistability between the continuous and the mode-locking regimes is pointed out. The effect of the total group velocity dispersion is described with a master mode-locking equation. PACS 42.55.Wd; 42.65.Re 相似文献
8.
The multisource location-allocation problem in continuous space is investigated. Two constructive heuristic techniques are proposed to solve this problem. Both methods are based on designing suitable schemes for the generation of the initial solutions. The first considers the furthest distance rule and is enhanced by schemes borrowed from tabu search such as constructing the forbidden regions and freeing strategy. The second considers the discrete solutions found when solving the p-median problem. Some results on existing test problems are presented. 相似文献
9.
The 1H and 13C NMR spectra of methylenecyclopropane, both in the isotropic phase and in the Merck IV nematic phase, were analysed. The relative signs of the 13C H scalar coupling constants were determined. The complete geometry deduced from this study was compared with that from a microwave study, and the discrepancies are discussed. 相似文献
10.
A. Salhi 《Theoretical and Computational Fluid Dynamics》2002,15(6):339-358
Linear theory is applied to examine rotation and buoyancy effects on homogeneous turbulent shear flows with given vertical
velocity shear, S=d/dx
3. In the rotating shear case (where the rotation vector is perpendicular to the plane of the mean flow, Ω
i
=Ωδ
i
2), general solutions for the Fourier components of the fluctuating velocity are proposed. These solutions are compared with
those proposed in the literature for the Fourier components of the fluctuating velocity and density in the case of a homogeneous
stratified shear flow with vertical density gradient, S
ρ=d/dx
3. It is shown that from the normal mode stability stand point the Bradshaw parameter B=2Ω/S(1+2Ω/S) (in the rotating shear case) and the Richardson number R
i
(in the statified shear case) play similar roles in identifying the stability for all the wave components except in the case
where Ω·k=0, for which rotation has no effects on the flow.
Analysis of the long-time behavior of the non-dimensional spectral density of energy, e
g
, is carried out. In the stable case, e
g
has decaying oscillations or undergoes a power law decay in time. Analytical solutions for the streamwise two-dimensional
energy ℰ
ii
1/2 (i.e. the limit at k
1=0 of the one-dimensional energy spectra) are proposed. At large time, ℰ
ii
1(t)/ℰ
ii
1(0) oscillates around the value (3R
i
+1)/(4R
i
) except at R
i
=1 it stays constant in time. Similar behavior for ℰ
ii
1(t)/ℰ
ii
1(0) is also observed in the rotating shear case (ℰ
ii
1(t)/ℰ
ii
1(0) oscillates around the value (1+4B)/(4B)).
Due to the behavior of the dimensionless spectral density of energy in both flow cases, the turbulent kinetic energy, /2, the production rate, ?, and the rate due to the buoyancy forces, ℬ, are split into two parts, , ?=?1+?2, ℬ=ℬ1+ℬ2 (in the stratified shear case, both ?1 and ℬ1 vanish when R
i
>?, while in the rotating shear case one has ℬ=0). It is shown that when rotation is “cyclonic” (i.e. Ω/S>0), part reaches maximum magnitudes at St
≈2, independent of the B value, and the first time to a zero crossing of ?2 occurs at this particular value. When rotation is “anticyclonic” (i.e. Ω/S<0) one finds St
≈1.6 instead of St
≈2. In the stratified shear case, both ?2 and ℬ2 cross zero at Nt=St
≈2, and part reaches maximum magnitudes at this particular value. These results and in particular those for the turbulent kinetic energy
are compared with previous direct numerical simulation (DNS) results in homogeneous stratified shear flows.
Received 30 July 2001 and accepted 19 February 2002 相似文献