Modeling and Simulating for Two Dimensional Infrared Photonic Crystal Devices

In order to design infrared devices efficiently, dispersive properties of two dimensional photonic crystal is studied in this paper. A model of eigenfrequencies is created by combining the variational expression with the conformal finite-difference time-domain (C-FDTD) technique. Useful data obtained by presentation can be applied to the analysis of the dispersion curves and design of the near-infrared waveguides.     

On Compatibility of Interval Fuzzy Preference Relations

This paper defines the concept of compatibility degree of two interval fuzzy preference relations, and gives a compatibility index of two interval fuzzy preference relations. It is proven that an interval fuzzy preference relation B and the synthetic interval fuzzy preference relation of interval fuzzy preference relations A ₁,A ₂,...,A _s are of acceptable compatibility under the condition that the interval fuzzy preference relation B and each of the interval fuzzy preference relations A _l,A ₂,...,A _s are of acceptable compatibility, and thus a theoretic basis has been developed for the application of the interval fuzzy preference relations in group decision making.     

一种新的面向事实的快速建模方法

针对UML进行快速原型开发的不便，提出了面向事实快速建模的思想。首先，探讨了面向对象技术以及标准建模语言UML的特点；然后，提出面向事实快速建模的思想并进行了研究，最后用实例进行了验证。     

603、675装甲钢动态性能测试及本构关系建立

利用一维Hopkinson压杆实验设备，对603、675两种装甲钢的动态压缩力学性能进行了较为系统的测试，在此基础上建立了2种装甲钢的Bodner-Partom本构方程，经程序计算与实际试验结果对比，表明本构方程能够较好地反映材料在动载荷条件下的力学行为．     

Relationship between the positive temperature coefficient of resistivity and dynamic rheological behavior for carbon black‐filled high‐density polyethylene

Studies on the relationship between resistivity and dynamic rheological properties of carbon black‐filled high‐density polyethylene (CB/HDPE) composites were carried out. Change of resistivity ρ is associated with the dynamic modulus before the positive temperature coefficient/negative temperature coefficient (PTC/NTC) transition temperature. When the temperature approaches the melting point of HDPE, ρ increases rapidly with a decreasing modulus, corresponding to PTC transition. The resistivity‐dynamic viscoelasticity relationship in the PTC region can be divided into two parts in which the changes of ρ with storage modulus G′ and loss modulus G″ can be described by the scaling laws given by the critical storage modulus and loss modulus G′_c and G″_c; adjustable parameters ρ′_1c, ρ′_2c, ρ″_1c and ρ″_2c; and nonlinear exponents n and m, respectively. The accordance between the experimental data and the scaling functions of the dimensionless quantities (G′/G′_c ? 1) and (G″/G″_c ? 1) in the PTC transition region suggests that the ρ jump may be the result of a modulus‐induced percolation. G′_c and G″_c increase, but the four scaling resistivitis, ρ′_1c, ρ′_2c, ρ″_1c, and ρ″_2c, decrease with increasing CB concentration, implying that the microstructure change of the composites is the determinant factor for the PTC behavior and the resistivity‐dynamic modulus relationship. However, ρ′_2c and ρ″_2c exhibit no scaling dependence. It is suggested that a threshold concentration exists for the modulus of the composites on the basis of examining the plot of both G′_c and G″_c against CB concentration. The scaling laws G′ ～ Φ^x and G″ ～ Φ^y hold for the concentration dependence of the critical modulus when Φ > Φ_c and the estimated values of x and y are 1.10 ± 0.10 and 0.89 ± 0.29, respectively. The resistivity‐dynamic modulus can shift to form a master curve. The horizontal factors a_G′ and a_G″ and the vertical factors a′ and a″ are relevant to the concentration dependence of the dynamic modulus or PTC behavior. It is believed that the former would be involved in changing the mechanical microstructure formed by the complicated interaction of CB particle and polymer segments, and the latter would be involved in the overall changes of conducting a network during the PTC transition region. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 983–992, 2003     

Surface versus bulk pinning in a HgBa2Ca2Cu3O8+x ceramics

Flux creep measurements on a HgBa₂Ca₂Cu₃O_8+x ceramics are reported. The results of the magnetic relaxation measurements are analyzed both by assuming that the pinning is due to the existence of a surface barrier or exclusively caused by bulk pinning. The action of both the surface and the bulk barriers is evidenced. At 70 K, a very high critical current density of the surface currents is determined, which is higher than the critical current density of the bulk. The field and temperature dependence of the pinning behaviour reflects mainly bulk pinning in 2D. The measurements were repeated after 4 and 12 months to investigate the influence of aging. A destruction of the superconducting properties of the grain boundaries accompanied by a degradation of the surfaces of the grains with time is proved.     

Linear analysis of cyclotron-cherenkov and cherenkov instabilities in dielectric-loaded coaxial waveguides

We present, based on the cold fluid theory, linear analysis of the Cherenkov and cyclotron-Cherenkov instabilities which are driven when a linear electron beam is injected into a dielectric-loaded waveguide immersed in an axial magnetic field. In the analysis we consider azimuthally symmetric TM_0n modes. We derive dispersion relations for three types of waveguide, and compare computationally obtained linear growth rates of both instabilities. For the type A, which consists of a metallic cylinder with dielectric liner on its inner surface, the growth rate of the Cherenkov instability is larger than that of the cyclotron-Cherenkov instability. For the type B, which consists of a dielectric core and an outer metallic cylinder, both growth rates are comparable. And for the type C, which consists of a metallic core with dielectric liner on its surface and an outer metallic cylinder, the growth rate of the latter instability is higher than that of the former instability. Finally, for the type C, obtained are dependences of the oscillation frequency and the growth rates of both instabilities on the following parameters: the beam energy, the beam current, the axial magnetic field, the dielectric constant, and the thickness of the dielectric.     

Elitist genetic algorithm for assignment problem with imprecise goal

The objective of this research paper is to solve a generalized assignment problem with imprecise cost(s)/time(s) instead of precise one by elitist genetic algorithm (GA). Here, the impreciseness of cost(s)/time(s) has been represented by interval valued numbers, as interval valued numbers are the best representation than others like random variable representation with a known probability distribution and fuzzy representation. To solve these types of problems, an elitist GA has been developed with interval valued fitness function. In this developed GA, the existing ideas about the order relations of interval valued numbers have been modified from the point of view of two types of decision making viz., optimistic decision making and pessimistic decision making. This modified approach has been used in the selection process for selecting better chromosomes/individuals for the next generation and in finding the best as well as the worst chromosomes/individuals in each generation. Here two new crossover schemes and two new mutation schemes have been introduced. In order to maintain the feasibility with crossover operations, a repair algorithm has been suggested. Extensive comparative computational studies based on different parameters of our developed algorithm on one illustrative example have also been reported.     

FILTERING CHARACTERISTICS OF DOUBLY SINUSOIDAL PERIODIC MEDIA

Dispersion and filtering characteristics of doubly sinusoidal periodic (DSP) medium is investigated. Based on its feature different from singly sinusoidal periodic medium, a novel dual-band filter model is realized and measured. The results show that even a single unit cell of DSP medium can provide rather good filtering performance. And the filter is of perfect compatibility with regular waveguide and substrate integrated waveguide technology. *Supported in part by 60171014 and 50577029 NSFC, P. R. China.     

Relations between two types of polarized partitions

It is shown that close links exist between two important types of polarized partition relations of higher dimensions. Project supported by a South-South Fellowship of the Third World Academy of Sciences and by the National Natural Science Foundation of China (Grant No. 19671061).