Abstract: CDMA multiuser detection (MUD) is a crucial technique to mobile communication. We adopt improved particle swarm optimization (PSO) algorithm in MUD which incorporates factor and utilizes function to discrete PSO. Comparison of BER and near-far effect has verified its effectiveness on multi-access interference (MAI). The algorithm accelerates the convergent speed meanwhile it also displays feasibility and superiority in case simulation.
Abstract: Based on the CFD/CSD (Computational Fluid Dynamics / Computational Structural Dynamics) algorithm, flutter characteristic and fluid structure interaction (FSI) problems of turbomachinery blades were studied in present paper. The three-dimensional unsteady Navier-Stokes equations and three-dimensional structural model were solved by the finite volume method and the finite element method, respectively. High accuracy in calculation and data exchange were gained by using load transfer, deformation tracking and synchronization between two solvers. The procedure successfully simulated the aeroelastic responses of a high performance fan rotor, NASA Rotor 67, over a range of operational conditions, and the results were compared with the experiment. The results show that the flutter mechanics of the compressor blade could be illustrated based on mean pressure and the distribution of cycle work, which is helpful for the decision of compressor stability.
Abstract: Gene expression programming (GEP) is a kind of phenotype/genotype based evolutionary computation. Code reuse is an important issue in GEP. Various methods are used in current literature to achieve this task. In this paper, we compared six GEP based algorithms by experiments. We proved that although it’s possible invent different kinds of code reuse strategies, current available strategies are powerful and efficient.
Abstract: In solving non-linear inverse optimization problems, how to make sure one and only solution and cut down computational effort are two very representative challenges. As thus, the derivative-free filled function method is proposed, it couples the classical filled method theory and dynamic canonical descent method. The application results of non-linear inverse analysis of material parameters for a practical engineering show that the derivative-free filled function method can quickly solve non-linear inverse problems with one and only solution, and it will be robust one in non-linear inverse solution field.
Abstract: This paper investigates the delay-dependent robust stability of neutral systems with time-varying discrete delays and time-varying structured uncertainties. New delay-dependent stability criteria are obtained and formulated in the form of a linear matrix inequality. Since the criteria take the sizes of the neutral delay, discrete delay and derivative of discrete delay into account, they are less conservative than previous methods. Numerical example is given to indicate significant improvements over some existing results.
Abstract: Based on Mawhin's continuation theorem and some analysis skill, some sufficient conditions for the existence of periodic solutions for a kind of second order differential equation with multiple deviating arguments are obtained. Results obtained in this paper extend the existing results.
Abstract: The use of piezoelectric material as transducer is prevalent. Piezoelectric bending mode element can be used for vibration energy harvesting because it can convert mechanical energy into electrical energy. In this article, electrical impedance characterization and equivalent circuit of triple-layer piezoelectric bender are discussed. Triple-layer piezoelectric bending device is fabricated, measured and modeled. This paper is aimed to explore simple but practical equivalent circuit models, expressed using electrical parameters of triple-layer piezoelectric bender and investigate the applicability of the Van Dyke circuit model and the complex circuit model in modeling the specimen’s equivalent circuit. The models produced impedance curves that closely matched the impedance measured for piezoelectric sample. The impedance characterization can provide a good understanding on the electrical behaviors of the triple layer piezoelectric bender when analyzing the performance of piezoelectric device.
Abstract: The plastic-coated slideways have been widely used for form-generating movement in machine tools. Its dynamic behavior plays an important role in the vibration properties of the whole machine. In this work, according to the situation that researches on this subject were rather insufficient, a theoretical research was analyzed concerning the stiffness and damping characteristics of rectangle-shaped plastic-coated slideways. The mathematical model was firstly suggested especially based on the assembly of the saddle and worktable. Both stiffness and damping characteristics on vertical and horizontal directions were theoretically determined. To derive the governing motion equation of the slideway system, the carriage and rail were considered as rigid bodies and connected with a series of spring and damping elements at the joint face. Moreover, through the Lagrange’s approach, the frequencies of the carriage at vertical, pitching, yawing and rolling vibration mode were identified.
Abstract: Wireless Sensor Networks (WSNs) enable susceptible sensing of the environment, offering unprecedented opportunities for observing the physical world. Acoustic source localization is an interesting topic with many possible application areas, such as intruder detection, sniper localization, automatic tracking of speakers and so on. Many existing algorithms are on the premise that the exact coordinates of sensor nodes are already known. In this paper, we propose a vector-based advanced TDoA algorithm that would calibrate the coordinate of the acoustic source by the non-prepositioned nodes. In the meanwhile, the portable sensor nodes would adjust themselves through the feedback of the estimated positions as well. Finally, we show that the proposed mechanism has high accuracy through experiments.