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Search Results: 1 - 10 of 127244 matches for " Desheng Li "
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Smooth Morse-Lyapunov Functions and Morse Theory of Strong Attractors for Nonsmooth Dynamical Systems
Desheng Li
Mathematics , 2010,
Abstract: In this paper we first construct smooth Morse-Lyapunov functions of attractors for nonsmooth dynamical systems. Then we prove that all open attractor neighborhoods of an attractor have the same homotopy type. Based on this basic fact we finally introduce the concept of critical group for Morse sets of an attractor and establish Morse inequalities and equations.
Morse Theory of Attractors via Lyapunov Functions
Desheng Li
Mathematics , 2010,
Abstract: This paper is concerned with the Morse theory of attractors for semiflows on complete metric spaces. First, we construct global Morse-Lyapunov functions for Morse decompositions of attractors. Then we extend some well known deformation results in the critical-point theory to Morse-Lyapunov functions which are only continuous. Based on these works, we finally introduce the concept of critical groups for Morse sets and establish Morse inequalities and Morse equations for attractors.
New exact solutions for the (2+1)-dimensional Boiti-Leon-Manna-Pempinelli equation
Ying Li,Desheng Li
Applied Mathematical Sciences , 2012,
Abstract:
A Formal Modeling and Implementation of Particle Swarm Optimizer for QoS-Aware Service Selection with an Extended Pi Calculus
Desheng Li,Na Deng
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: For past years, Particle Swarm Optimization (PSO), one of the evolutionary computational techniques, has been intensively studied and applied in both academia and industry. Recently there has been a shift from consideration of design of concrete algorithms to a consideration of the formalization models of optimization approaches. However, the meta-search procedure is not the primitive of the algebra, which not participates in the derivation of the inference of expressions. For this reason, the models above could not be seen as a unity in a strict mathematics form. Moreover, the operators of traditional algebra limit the express of complicated processes, such as concurrent patterns. As a result, the cost calculation of the whole process is not an easy thing only according to the algebraic form itself. Attempting to solve these issues, a new formal modeling of particle swarm optimizer from a perspective of an extend version of Pi calculus is proposed in this study, which treats the whole operations in PSO as a kind of meta-search procedure and owns the cost operator and other operators supporting concurrent patterns. On the basis of this algebra, the QoS-aware service selection problem can be seen as a particular cost derivation under the LTS semantics. Based on the theoretical model, a simulator with a core of Pi calculus compiler is developed to verify our theory and also show the practical applicability in a real scenario.
Conference Control Design for a SIP-Web-Service Hybrid Multimedia Conference Framework
Desheng Li,Na Deng
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: Session Initiation Protocol (SIP) and Web service are the de facto standards for Voice over IP applications and distributed system, respectively. Although they do not be used to define multimedia conferencing directly and completely, many proposals, drafts and papers suggest extensions and solutions to this essential service. However, as the spring up of the Web service standards and technology, some traditional communication systems should be restructured and modified, including the multimedia conference framework based on SIP and Web service. In this study, a hybrid multimedia conference framework is first propose, which consist of low latency services, primitive and composite conference services. Under this framework, a multimedia conference can be organized and controlled conveniently with the property of loosely coupling and extensibility. Then the primary components of a conference control are introduced followed by the detailed design exemplified by some typical scenarios, which is compared to other possible design approaches. Finally, a specification of orchestration implementation which realizes the synthesis of the conference control functions is introduced to illustrate the feasibility of this design.
A New Cooperative Particle Swarm Optimizer and its Application in Permutation Flow Shop Scheduling Problem
Desheng Li,Na Deng
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: In this study, a new variant of Particle Swarm Optimization, Electoral Cooperative PSO (ECPSO), is presented and applied into solving the Permutation Flow Shop Scheduling Problem (PFSSP). Firstly, an electoral swarm is generated by the voting of primitive sub-swarms and also participates in evolution of swarm, whose particle candidates come from primitive sub-swarms with variable votes from them. Besides, a fast fitness computation method using processing time matrix of a valid schedule is also imported to accelerate the calculation of makespan function. On the other hand, in order to prevent trapping into local optimization, a disturbance factor mechanism is imported to check the particles movements for resetting the original subswarms and renewing the electoral swarm. To test the basic use and performance of ECPSO, some experiments on function optimization are executed on functions with unfixed and fixed numbers of dimensions. The proposed method was also applied to well-known benchmark of PFSSP, Taillard dataset; the results demonstrated good performances and robustness of ECPSO compared to some versions of PSO.
Mobility Matrix of a Thin Circular Plate Carrying Concentrated Masses Based on Transverse Vibration Solution
Desheng Li,Junhong Zhang
Shock and Vibration , 2014, DOI: 10.1155/2014/284367
Abstract: When calculating the vibration or sound power of a vibration source, it is necessary to know the point mobility of the supporting structure. A new method is presented for the calculation of point mobility matrix of a thin circular plate with concentrated masses in this paper. Transverse vibration mode functions are worked out by utilizing the structural circumferential periodicity of the inertia excitation produced by the concentrated masses. The numerical vibratory results, taking the clamped case as an instance, are compared to the published ones to validate the method for ensuring the correctness of mobility solution. Point mobility matrix, including the driving and transfer point mobility, of the titled structure is computed based on the transverse vibration solution. After that, effect of the concentrated masses on the mechanical point mobility characteristics is analyzed. 1. Introduction Design of quiet and low vibration equipment requires quantitative data of the sound and vibration sources. Mechanical point mobility matrix is an appropriate tool to describe the dynamic characteristics and is needed for the estimation of vibration and sound power transmission from the source to the receiving structure if the energy based methods are used. In many cases, it is impossible to measure the point mobility needed for an analysis directly; therefore, it is necessary to calculate them in terms of the relative theory. Much work has been done in finding analytical formula for point mobility. Fahy [1], Fahy and Gradonio [2] and Cremer et al. [3] gave a comprehensive summary of formulas for kinds of classical structures, such as beams, plates, and shells. Many authors, among them Sarradj ?[4], Moorhouse and Gibbs ? [5], Bonhoff and Petersson [6], and Mayr and Gibbs [7], calculated various point mobility of beam/plate-like components in more or less detail. In contrast, more results of point mobility were applied in complicated and built-up structures. Petersson and Heckl [8] studied point mobility for the plate with arbitrary thickness and the deep beams. Sciulli [9] analyzed the true effects of vibrating system flexibility. Grice and Pinnington [10] estimated the mean-square flexural vibration of a thin plate box via calculating its mechanical impedances. Putra [11] modified Laulegnat’s model by applying impedance and mobility to research the sound radiation of a perforated plate. Wang [12] provided a general formula to solve the vibration problem for continuous systems. Yun and Mak [13] reported the effects of the interaction between two vibratory machines
Linking Theorems of Local Semiflows on Complete Metric Spaces
Desheng Li,Guoliang Shi,Xianfa Song
Mathematics , 2013,
Abstract: In this paper we prove some linking theorems and mountain pass type results for dynamical systems in terms of local semiflows on complete metric spaces. Our results provide an alternative approach to detect the existence of compact invariant sets without using the Conley index theory. They can also be applied to variational problems of elliptic equations without verifying the classical P.S. Condition. As an example, we study the resonant problem of the nonautonomous parabolic equation $ u_t-\Delta u-\mu u=f(u)+g(x,t) $ on a bounded domain. The existence of a recurrent solution is proved under some Landesman-Laser type conditions by using an appropriate linking theorem of semiflows. Another example is the elliptic equation $-\Delta u+a(x)u=f(x,u)$ on $R^n$. We prove the existence of positive solutions by applying a mountain pass lemma of semiflows to the parabolic flow of the problem.
Attractors of Local Semiflows on Topological Spaces
Desheng Li,Youbin Xiong,Jintao Wang
Mathematics , 2015,
Abstract: In this paper we introduce a notion of an attractor for local semiflows on topological spaces, which in some cases seems to be more suitable than the existing ones in the literature. Based on this notion we develop a basic attractor theory on topological spaces under appropriate separation axioms. First, we discuss fundamental properties of attractors such as maximality and stability and establish some existence results. Then, we give a converse Lyapunov theorem. Finally, the Morse decomposition of attractors is also addressed.
Research on an Improved Terrain Aided Positioning Model
Li Shidan,Liguo Sun,Xin Li,Desheng Wang
Journal of Software , 2011, DOI: 10.4304/jsw.6.5.937-943
Abstract: Terrain aided positioning (TAP) is a kind of positioning method which acquires position information from the terrain elevation datum underneath the vehicle. This method has the characteristics of autonomy, all-weather, anti-interference, strong stealthiness and high accuracy. It is widely used in the navigation system for various aircrafts, cruise missiles and underwater vehicles. The fundamentals of TAP is that it firstly measures the terrain elevation underneath the vehicle using relevant sensors, then compares these datum with the referenced Digital Elevation Map (DEM) and acquires the position information through matching algorithm. The system model for TAP currently used totally depends on the referenced DEM and the position acquired is the position referenced to the map rather than the true position. Due to the DEM error which is introduced during production procedure, the position on the map is not the real position. In order to overcome the problem, the paper proposes an improved TAP model which introduces the map error into the system model and gets the recursive solution based on the Bayesian framework which is numerically solved by RPF particle filter. From the simulation results, the new model has extraordinary performance for handling the error of DEM and the algorithm can estimate the map error and acquire the accurate position.
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