基于GMPLS的动态分布式WDM网状网路由选择算法研究

研究了在基于GMPLS的WDM网络中,当节点不具备波长变换能力并且配备有限个光收发器对时,如何为到达的业务请求建立标记交换路径(LSP)的问题。提出一种以跳数和带宽碎片要求为权重,合理分配带宽资源的新算法。仿真结果表明,该算法在保证用户业务可靠性要求的同时,能够更有效地提高全网资源的利用率,并大大降低网络阻塞的可能性。     

On the two basic problems of complex damping theory

In this paper, two important basic problems relating to the complex damping theory are discussed. The two problems are: (1) the essence of complex damping, and (2) the dynamic solution of structures with complex damping in time domain. To investigate the above problems, the frequency-dependent viscous damping theory is established and the correct and applicable solution of forced vibration for a complex damping oscillator is given beforehand.Supported by the Joint Earthquake Foundation     

Characteristics and design procedure of hyperbolic dies

Nozzle profiles capable of generating constant extensional strain rates are termed hyperbolic dies. When used in polymer extrusion, they exhibit greater potential in inducing and retaining polymer molecular orientation than conventional capillary dies. Most mathematical expressions found in the literature involve several processing variables in describing and designing such nozzle profiles. This report reveals that a hyperbolic die profile, although rather complicated, can be expressed with equations in terms of two ordinary geometrical parameters—the exit diameter and the hyperbolic length. This finding greatly simplifies the design procedure of hyperbolic dies. The extensional strain rate of a hyperbolic die can be related to the length-to-diameter ratio for any given exit diameter. Examples of various types of die profiles are presented and their constant extensional strain-rate characteristics are discussed.     

Sorption and diffusion of water vapor in polyimide films

Sorption and diffusion of water vapor are investigated gravimetrically for polyimide films. The activity dependence of the solubility and diffusion coefficients, S and D, respectively, is classified under four types: (1) constant S and D type, (2) dual-mode sorption and transport type, (3) dual-mode type followed by a deviation due to a plasticization effect at high vapor activity, and (4) constant S and D type followed by a deviation due to water cluster formation at high activity. For the dual-mode type, the Henry's law component is much larger than the Langmuir component except at low activity, and therefore deviation in behavior from the first type is small. S is larger for polyimides with higher content of polar groups such as carbonyl, carboxyl, and sulfonyl. D is larger for polyimides with a higher fraction of free space, with some exceptions. The polyimide from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and dimethyl-3,7-diaminodibenzothiophene-5, 5-dioxide belongs to the third type and displays both large S and large D. The polyimide from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4′-oxydianiline belongs to the fourth type, and has the largest D but rather small S because of the hydrophobic C(CF₃)₂ groups. © 1992 John Wiley & Sons, Inc.     

InGaAsSb/AlGaAsSb长波长多量子阱激光器有源区的优化设计

系统地研究了波长为2.7μm的InGaAsSb/AlGaAsSb多量子阱激光器中有源区的优化设计.分别用含应变势的6带KP模型和抛物带模型计算价带和导带的能带结构，并得到薛定谔方程和泊松方程的自洽解，由此计算量子阱在载流子注入时的增益谱.研究表明制约量子阱增益的主要因素不是跃迁矩阵元，而是粒子数反转程度，尤其是空穴填充HH1子带的概率.增加压应变或减小阱宽都会提高量子阱增益.前者降低了价带HH1子带空穴的平面内有效质量；后者拉大了价带子带间距，尽管它同时略微增加了空穴有效质量.这两种因素都导致价带顶空穴态     

Bulk and microscopic properties of copolymer networks in mixed aqueous solvents

Amphiphilic films and hydrogels have been prepared from ethanol/water solutions containing a hydrocarbon-grafted water-soluble cellulose ether. These materials are characterized by dispersed hydrophobic microdomains which form spontaneously in the solvent due to the inherent incompatibility of the side chains with water. At low applied shear stress, the microdomains behave as temporary linkages of finite lifetimes, imparting viscoelastic properties to the networks. The molecular weight between microdomains was found to be independent of the volume fraction of polymer in the gel, and the number of linkages per backbone ranges from 22.8 ± 1.3 to 26.2 ± 1.5 over the frequency range 30–50 rad/s. The behavior of the solutions and gels was characterized using fluorescence and dynamic rheological measurements. It was demonstrated that the microdomains are capable of sequestering water-insoluble solutes. © 1992 John Wiley & Sons, Inc.     

On the modulation of ion-acoustic solitary waves in a cylindrical warm plasma near critical density

Summary We have derived a modified cylindrical K-dV (MCK-dV) equation for an ion-acoustic wave in a warm plasma with two-temperature electrons, in a cylindrical geometry, near the critical density where the nonlinearity of the usual CK-dV vanishes. The solitary-wave solution of MCK-dV is then discussed analytically using the concept of adiabatic invariants and the basic theorem due to Lax, instead of any numerical evaluation. This modulated form of the solitary wave is then discussed graphically as regards its variation with respect to the change in concentration of law- and high-temperature electrons.     

Single and Multi-Interval Legendre τ-Methods in Time for Parabolic Equations

In this paper, we take the parabolic equation with periodic boundary conditions as a model to present a spectral method with the Fourier approximation in spatial and single/multi-interval Legendre Petrov–Galerkin method in time. For the single interval spectral method in time, we obtain the optimal error estimate in L ²-norm. For the multi-interval spectral method in time, the L ²-optimal error estimate is valid in spatial. Numerical results show the efficiency of the methods.     

Mechanisms of reduction in hole concentration in Al-doped 4H-SiC by electron irradiation

From the temperature dependence of the hole concentration in unirradiated lightly Al-doped 4H-SiC epilayers, an Al acceptor with E_V + 0.2 eV, which is an Al atom (Al_Si) at a Si sublattice site, and an unknown deep acceptor with E_V + 0.35 eV are found, where E_V is the top of the valence band. Both the densities are similar. With irradiation of 0.2 MeV electrons the Al acceptor density is reduced, while the unknown deep acceptor density is increased. Judging from the minimum electron energy required to displace a substitutional C atom (C_s) or the Al_Si, the bond between the Al_Si and its nearest neighbor C_s is broken due to the displacement of the C_s by this irradiation. Moreover, the displacement of the C_s results in the creation of a complex (Al_Si-V_C) of Al_Si and a carbon vacancy (V_C), indicating that the possible origin of the deep acceptor with E_V + 0.35 eV is Al_Si-V_C.     

光象散法测量溶液浓度的研究

本文报道一种用光象散技术测量溶液浓度的新方法。给出其理论解析、测量原理、系统构成与实验结果。从理论研究与初步实验结果表明,本方法用于自动测量溶液浓度有好的可行性与实用性,亦可作为在线监测。