FRP/塑料复合管道设计新方法——限定环向应变设计准则

根据FRP和塑料的不同技术性能特点,提出适用于FRP/塑料复合管道设计的限定环向应变设计准则。多年的工程实践表明,该设计方法简捷、可靠、实用性强,其安全系数取值更为准确、合理。

K最短路径算法综述

为了进一步推广应用K最短路径(K shortest paths,KSP)算法并为深入研究该类算法提供相关资料。根据路径限制条件,将KSP问题分为一般KSP问题和限定无环KSP问题,归纳总结了求解每类KSP问题的基本思路、研究现状和研究进展。KSP问题非常复杂,在实际应用中所需处理的数据规模非常庞大,使得算法效率成了评价KSP算法的一个重要指标。在分析各种KSP算法时尤其关注其时间复杂度,指出KSP问题未来的研究方向,将为满足多约束的最短路径等问题的研究提供有益的参考。

一种改进的求解前N条最短路径问题的多重标号算法

求前N条最短路径问题是一个在实际工程中有着广泛应用背景的重要问题.针对传统问题描述中存在的局限,对该问题的定义进行了扩展,从而使此问题的求解更为完备.介绍了求解传统N最短路径问题的多重标号算法的基本思想,分析了其存在的问题,提出了相应的针对扩展N最短路径问题的改进算法.在详细描述算法实现的基础上,对改进算法的时间和空间复杂度进行了理论分析,并分别与理论严密算法中的候选删除边算法和有损算法中的遗传算法进行了对比实验.结果表明,本文算法能以更好的时间性能正确地求解得到全局最优路径集.

Limit Cycles in the Stability Analysis of a Chemical System

Aris and Amundson studied a chemical reactor and obtained the two equationsDaoud showed that at most one limit cycle may exist in the region of interest. Itis showed in this paper that other singular points exist and that a stable limitt cycle existsaround the singularity (1/2, 2) when K∈(9-δ, 9).

Hopf Bifurcation Control of a Hyperchaotic Circuit System

This paper is concerned with the Hopf bifurcation control of a new hyperchaotic circuit system. The stability of the hyperchaotie circuit system depends on a selected control parameter is studied, and the critical value of the system parameter at which Hopf bifurcation occurs is investigated. Theoretical analysis give the stability of the Hopf bifurcation. In particular, washout filter aided feedback controllers are designed for delaying the bifurcation point and ensuring the stability of the bifurcated limit cycles. An important feature of the control laws is that they do not result in any change in the set of equilibria. Computer simulation results are presented to confirm the analytical predictions.

The Stable Limit Cycles of a Generalized Lienard Equation

In this paper we give a series of sufficient conditions for the existence of autonomous systems with three singular points.

Optimization of block-floating-point realizations for digital controllers with finite-word-length considerations

The closed-loop stability issue of finite-precision realizations was investigated for digital control-lers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resultingfrom using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization.

Normal Form of the Elliptic Curve Over the Finite Ring

In this work, we will to study the equation of an elliptic curve over the ring An = F2d [E], en = 0.,where d. is a positive integer. More precisely we defined the J-invariant of an elliptic curves over the ring An and we establish re（J） = j, wherej is the j-invariant of an elliptic curve over the field F2d and re is the canonical projection defined over ring An by F2d , see [1].

Threshold Ring Signature Scheme Based on TPM

The conventional ring signature schemes cannot address the scenario where the rank of members of the ring needs to be distinguished, for example, in electronically commerce application. To solve this problem, we presented a Trusted Platform Module （TPM）-based threshold ring signature schen. Employing a reliable secret Share Distribution Center （SDC）, the proposed approach can authenticate the TPM-based identity rank of members of the ring but not track a specific member＇s identity. A subset including t members with the same identity rank is built. With the signing cooperation of t members of the subset, the ring signature based on Chinese remainder theorem is generated. We proved the anonymity and unforgeability of the proposed scheme and compared it with the threshold ring signature based on Lagrange interpolation polynomial. Our scheme is relatively simpler to calculate.

基本电路

Y98-61305-617 9905972一种 MOSFET-双极非线性负阻振荡器=A class of theMOSFET-bipolar nonlinear negative resistance oscillator[会,英]/Vizireanu,D.N.& Serban,R.//1997 Pro-ceedings of the International Semiconductor Conference,Vol.2.—617～620(UV)提出了一种 MOSFET-双极非线性负阻效应。说明了电压-电流方程用数学模型。研究了单模式 LCR网络振荡器的相关非线性微分方程的数学特性。证明了在适合条件下,能够产生小振幅稳定的限定环路振荡。获得了周期解的分析近似值。还将此预计与用数字积分获得的结果进行了比较。

HOMOCLINIC BIFURCATION WITH CODIMENSION 3

First it is proved that both the integral of the divergence and the Melnikov function are invariants of the C2 transformation. Then, the problem of the planar homoclinic bifurcation with codimension 3 is considered. It is proved that, in a small neighborhood of the origin in the parameter space of a Cr (r≥5) system, there exist exactly two Cr-1 semi- stable- limit- cycle branching surfaces, and their common boundary is a unique Cr-1 three-multiple- limit-cycle branching curve. The bifurcation pictures and the asymptotic expansions of the bifurcation functions are given. The stability criterion for the homoclinic loop is also obtained when the integral of the divergence is zero. The proof of the auxiliary theorems will be presented in [16].

Characteristic analysis of hydraulic hybrid vehicle based on limit cycle

The theory of limit cycles was applied to hydraulic hybrid vehicle (HHV) to analyze the dynamic characteristics of the system. The exact mathematical models based on configuration diagram of HHV were built to study on equilibrium points, nonexistence of limit cycle and stability of equilibrium points. The analysis showed that if the Young's modulus of fluid is neglected, the equilibrium points of the system will be distributed on both sides of the initial function. In addition, there is a unique equilibrium point according to the practical signification of the system parameters. The nonexistence analysis showed that there is no limit cycle for the system, no matter how the viscosity coefficient B changes. The stability analysis of equilibrium points showed that the system is asymptotically stable about the equilibrium point at B≥0 and the equilibrium point is the center point of the system at B=0. Finally, the phase diagrams of global topological structure of HHV system were entirely described according to qualitative analysis of the singular points at infinity.

Alternative food and external source of infection stabilize predator-prey oscillations -- A conclusion drawn from an eco-epidemiological model

Das et al. [Effect of disease-selective predation on prey infected by contact and external sources, Biosystems 95（3） （2009） 188-199] proposed an eco-epidemiological model where the prey species is infected through the external source of infection and contact of the species. In this present study we have modified their model by assuming that the predator consumes both the susceptible as well as the infected prey following the modified Holling type-Ⅱ functional response. Our main focusing points of this study are the role of infection rate （both internal and external）, alternative food, and half-saturation constant in the predator prey dynamics with disease in the prey population. We have shown the local stability of the boundary as well as the interior equilibrium point under certain conditions. We have Mso worked out the permanence of the system. Our simulation results show that the system enters into limit cycle oscillations from stable position for higher values of the contact rate. But it is also shown that the external infection rate, enrichment of the alternative food of the predator population and the half-saturation constant can prevent limit cycle oscillations and stabilize the system. Thus external dis- ease propagation, enrichment of the alternative food resource, and the half-saturation constant are the key factors for preventing the oscillatory behavior of the species.

Asymptotic behavior of a tagged particle in the exclusion process on parallel lattices

We investigate a tagged particle in the exclusion processes on {1,..., N }×Zd, with different densities in different levels {k} × Zd, ? k. Ignoring the level the tagged particle lying in, we only concern its position in Zd,denoted by Xt. Note that the whole space is not homogeneous. We define the environment process viewed from the tagged particle, of which Xt can be expressed as a functional. It is called the tagged particle process. We show the ergodicity of the tagged particle process, then prove the strong law of large numbers. Furthermore, we show the central limit theorem of Xt provided the zero-mean condition.

Identification and robust limit-cycle-oscillation analysis of uncertain aeroelastic system

Model uncertainty directly affects the accuracy of robust flutter and limit-cycle-oscillation (LCO) analysis. Using a data-based method, the bounds of an uncertain block-oriented aeroelastic system with nonlinearity are obtained in the time domain. Then robust LCO analysis of the identified model set is performed. First, the proper orthonormal basis is constructed based on the on-line dynamic poles of the aeroelastic system. Accordingly, the identification problem of uncertain model is converted to a nonlinear optimization of the upper and lower bounds for uncertain parameters estimation. By replacing the identified memoryless nonlinear operators by its related sinusoidal-input describing function, the Linear Fractional Transformation (LFT) technique is applied to the modeling process. Finally, the structured singular value(μ) method is applied to robust LCO analysis. An example of a two-degree wing section is carded out to validate the framework above. Results indicate that the dynamic characteristics and model uncertainties of the aeroelastic system can be depicted by the identified uncertain model set. The robust LCO magnitude of pitch angle for the identified uncertain model is lower than that of the nominal model at the same velocity. This method can be applied to robust flutter and LCO prediction.

Stability and multi-parametric Hopf bifurcation analyses of viral infection model with time delay

Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. This paper deals with stability and bifurcation analyses of mathematical model that represents the dynamics of HIV infection of thymus. The existence and stability of the equilibria are investigated. The model is described by a system of delay differential equations with logistic growth term, cure rate and discrete type of time delay. Choosing the time delay as a bifurcation parameter, the analysis is mainly focused on the Hopf bifurcation problem to predict the existence of a limit cycle bifurcating from the infected steady state.Further, using center manifold theory and normal form method we derive explicit formulae to determine the stability and direction of the limit cycles. Moreover the mitosis rate r also plays a vital role in the model, so we fix it as second bifurcation parameter in the incidence of viral infection. Our analysis shows that, while both the bifurcation parameters can destabilize the equilibrium E＊ and cause limit cycles. Numerical simulations are performed to investigate the qualitative behaviors of the inherent model.