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71.
Bassem Ben Hamed Imen Ellouze Mohamed Ali Hammami 《Mediterranean Journal of Mathematics》2011,8(4):603-616
In this paper, we investigate the problem of global uniform practical exponential stability of a general nonlinear non autonomous
differential delay equations. Using the global uniform practical exponential stability of the corresponding differential equation
without delay, we show that the differential delay equation will remain globally uniformly practically exponentially stable
provided that the time-lag is small enough. Finally, some illustrative examples are given to demonstrate the validity of the
results. 相似文献
72.
In the present paper, a method is proposed for topology optimization of continuum structures subject to static and plastic admissibility conditions relative to a prescribed load. A key feature of the method is that, using a finite-element discretization, the form of the resulting topology optimization problem is similar to that of the direct static approach of the limit analysis problem. The proposed method is formulated in plane strain using Tresca materials and is illustrated on example problems taken from the literature. 相似文献
73.
Mathematical Notes - In this work, we investigate the following fractional $$p$$ -Laplacian equation involving a concave-convex nonlinearities as follows, $${\rm (P_\lambda)} \begin{cases}... 相似文献
74.
Using a light scattering technique at a fixed temperature, we have investigated viscoelastic behaviour exhibited by the ferroelectric smectic phase (SmC*) of C8tolane in a homeotropic orientation. Experiments were performed in backward and forward scattering geometries that allowed us to deduce separately orientational diffusivities k3/η and k+/η corresponding to the Goldstone mode. The k3/η value measured in the SmC* phase is about 100 times higher than in the SmCA* phase exhibited by the same liquid crystal compound. The factor 100 may be attributed in great part to the molecular arrangement mode in adjacent smectic layers. However k+/η measured in the SmC* phase is in the same order of magnitude as those measured previously in SmCA* phases. 相似文献
75.
Aris A Syntetos Mohamed Zied Babai Shuxin Luo 《The Journal of the Operational Research Society》2015,66(12):2061-2074
Intermittent demand items dominate service and repair inventories in many industries and they are known to be the source of dramatic inefficiencies in the defence sector. However, research in forecasting such items has been limited. Previous work in this area has been developed upon the assumption of a Bernoulli or a Poisson demand arrival process. Nevertheless, intermittent demand patterns may often deviate from the memory-less assumption. In this work we extend analytically previous important results to model intermittent demand based on a compound Erlang process, and we provide a comprehensive categorisation scheme to be used for forecasting purposes. In a numerical investigation we assess the benefit of departing from the memory-less assumption and we provide insights into how the degree of determinism inherent in the process affects forecast accuracy. Operationalised suggestions are offered to managers and software manufacturers dealing with intermittent demand items. 相似文献
76.
This article proposes the construction of Wigner measures in the infinite dimensional bosonic quantum field theory, with applications
to the derivation of the mean field dynamics. Once these asymptotic objects are well defined, it is shown how they can be
used to make connections between different kinds of results or to prove new ones.
Submitted: January 1, 2008., Accepted: July 1, 2008. 相似文献
77.
T. Othman Corresponding author Z. Hammami A. Gharbi H. T. Nguyen 《Liquid crystals》2013,40(8):1061-1067
We have investigated the viscoelastic behaviour exhibited by chiral smectic C* phases in homeotropic orientation. For an appropriate scattering geometry and using the light scattering technique, the orientational diffusivities associated with the Goldsone mode in ferro- and antiferroelectric phases of C11thiobenzoate and C8tolane compounds have been measured. (SmCA*) is about 100 times weaker than (SmC*). This divergence may be largely attributed to the mode of the molecular arrangement in ferro- and antiferroelectric phases, in spite of the same helical structure observed in the two phases. 相似文献
78.
F. Hammami S. Ben Mabrouk A. Mami 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(3):207-220
ABSTRACTIn this paper, a mathematical model is developed based on the heat transfer of stored grains aerated in a cylindrical silo. This work is a part of study that aims to model the whole process of cereal storage system including a dehumidifier. The use of dehumidifier is intended to remove excess moisture from the airflow injected by the ventilator system in the silo filled with wheat, and to keep hygroscopic properties of grain in safe level during the storage period. Temperature and humidity are the two important variables coupled to control the process and to preserve grain quality. The laboratory device permitted us to achieve several tests for different conditions of grain stored in silo without aeration. A simulation of the airflow through the thermal space of the silo and grain parameters has been carried out. The results are reasonably in agreement with experiments and other published data. The system performance is evaluated at critical conditions of storage boundaries. 相似文献
79.
Zied Cheheb Fethi Albouchi Sassi Ben Nasrallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(4):620-635
This paper deals with a theoretical and an experimental study allowing the measurement of the radiative and the conductive properties of semitransparent materials. The method consists of applying a crenel heat flux on the front face of a semitransparent sample and recording the temperature at the rear face using an open thermocouple junction.Parameter identification is performed by the minimization of the ordinary least-squares function comparing the measured and the calculated temperatures. This later is obtained from the thermal model describing the heat transfer by conduction and radiation in the medium. This model is built by the thermal quadrupole formalism.Measurements are reported on commercial glasses and plexiglass samples, and the used iterative algorithm is based on the Gauss-Newton method. 相似文献
80.
Zied Bahroun Jean-Pierre Campagne 《Journal of Mathematical Modelling and Algorithms》2010,9(4):311-342
The growing quality and delay requirements have catalyzed the emergence of new commercial paradigms, which have strongly modified
the customer–supplier relationship. Customers and suppliers become more and more linked with contracts or global orders spanned
over a relatively important period. This paper, examines a type of contract which specifies a fixed and cyclic delivery dates
with delivery quantities varying between a min and a max values. The exact delivery quantities are usually known only few
days before the delivery. A company which produces n items on a bottleneck facility is considered; each item is confronted
to a cyclic demand and has an important holding cost in comparison to set-up costs. We propose heuristic approaches, to build,
in a medium term level, cyclic production schedules. These schedules face the demand and minimize a total cost function composed
of holding and set-up costs. An experiment is proposed in order to prove the effectiveness of our approaches. 相似文献