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排序方式: 共有175条查询结果,搜索用时 46 毫秒
41.
《随机分析与应用》2013,31(3):591-613
This work is concerned with single machine scheduling with random compression of processing times. The objective is to find the optimal sequence to minimize the cost based on earliness, tardiness and compression. The analysis is carried out under a common due date. Both absolute derivation cost and squared derivation cost are considered. For both constrained problems and unconstrained problems, it is shown that an optimal schedule must be V-shaped. Remarks on common slack model is also provided. 相似文献
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We present a systematic study of the electron mobility in V-shaped AlGaAs/GaAs quantum wires taking into account the impurity (background, remote and interface) and the acoustic-phonon scattering. The electron scattering rates are calculated for wires with electron concentrations up to 106 cm−1 and temperatures up to 40 K by using Fermi’s golden rule. The effects of the interface roughness scattering and the alloy scattering are also discussed. The energy eigenstates and eigenvalues of the system under study are calculated using a finite difference method. We analyze the importance of each scattering mechanism on the mobility of several quantum wires of different qualities as a function of the electron concentration and the temperature. 相似文献
44.
估算金属切口的强度时,人们一般采用以Neuber准则为理论基础的Neuber法,或以Moski及Glinka的等效能量密度法为理论基础的能量法.本文以弹塑性幂硬化材料为研究对象,将两种方法得到的结果与实验结果进行了比较,发现Neuber法总是低估切口强度,而大多数情况下,能量法却高估切口强度,并且总的来说,能量法的精度高于Neuber法的精度;能量法的可靠性高于Neuber法的可靠性. 相似文献
45.
U. Yesilgul F. Ungan E. Kasapoglu H. Sar? I. Sökmen 《Superlattices and Microstructures》2011,50(4):400-410
In this study, the changes in the optical absorption coefficients and the refractive index in a V-shaped quantum well have investigated theoretically. Within the effective mass approximation, the electronic structure of the V-shaped quantum well is calculated by numerical methods from the Schrödinger equation. Optical properties are obtained using the compact density-matrix approach. In the present work, the linear, third-order nonlinear and total absorption and refractive index changes investigated as a function of the quantum well width, the incident optical intensity, strengths of the magnetic and electric fields. Our results show that the magnetic and electric fields strengths, the quantum well width and incident optical intensity have a great effect on the optical characteristics of these structures. 相似文献
46.
This paper is devoted to investigate the nonlinear behaviors of a V-shaped microcantilever of an atomic force microscope (AFM) operating in its two major modes: amplitude modulation and frequency modulation. The nonlinear behavior of the AFM is due to the nonlinear nature of the AFM tip–sample interaction caused by the Van der Waals attraction/repulsion force. Considering the V-shaped microcantilever as a flexible continuous system, the resonant frequencies, mode shapes, governing nonlinear partial and ordinary differential equations (PDE and ODE) of motion, boundary conditions, frequency and time responses, potential function and phase-plane of the system are obtained analytically. The governing PDE is determined by employing the Hamilton principle. Subsequently, the Galerkin method is utilized to gain the governing nonlinear ODE. Afterward, the resulting ODE is analytically solved by means of some perturbation techniques including the method of multiple scales and the Lindsted–Poincare method. In addition, the effects of different parameters including geometrical one on the frequency response of the system are assessed. 相似文献
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48.
Xin-Mei Li Meng-Qiu Long Li-Ling Cui Jin Xiao Xiao-Jiao Zhang Dan Zhang Hui Xu 《Physics letters. A》2014
Based on nonequilibrium Green's function in combination with density functional theory calculations, the spin-dependent electronic transport properties of one-dimensional zigzag molybdenum disulfide (MoS2) nanoribbons with V-shaped defect and H-saturation on the edges have been studied. Our results show that the spin-polarized transport properties can be found in all the considered zigzag MoS2 nanoribbons systems. The edge defects, especially the V-shaped defect on the Mo edge, and H-saturation on the edges can suppress the electronic transport of the systems. Also, the spin-filtering and negative differential resistance behaviors can be observed obviously. The mechanisms are proposed for these phenomena. 相似文献
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50.
In this paper we report the results from detailed electro-optical and dielectric studies in various antiferroelectric and ferroelectric phases of an orthoconic antiferroelectric liquid crystal (OAFLC) material . The material possesses high tilt and high spontaneous polarisation. Such an OAFLC, because of its high tilt, provides an excellent dark state. The material exhibits V-shaped switching in the SmC* phase. Dielectric studies reveal the existence of another phase during heating in the range between 78.6 and 92°C which did not appear in the DSC curve and in polarising microscopy. This phase has been identified as the SmCγ* phase and is extremely sensitive with respect to the cell conditions, aligning material, purity, etc. Three dielectric modes have been assigned in the above-mentioned temperature range and their origins are discussed. 相似文献