Advanced Materials Research Vols. 268-270

Abstract: The distributed database system is the product that the database system combines with the computer network system. The data distribution problem has great influence on distributed database application system improvement, data availability, the efficiency and reliability of the distributed database. The allocation strategies in this paper have used some excellent properties in genetic algorithms, including higher parallelism and robustness, the realization of standard way, and to maintain good balance between the depth prior search and breadth prior search, etc, so the allocation strategies in this article's have high execution efficiency, with stronger ability in seeking the best global solution and easy to realize.

Abstract: In this paper, a new kind of method which are called gradient-type method with perturbations are proposed and a new kind of nonmonotone line search technique is employed. At the same time, global convergence of these methods is proved only in the case where the gradient function is uniformly continuous on an open convex set containing the iteration sequence.

Abstract: H¹-Galerkin mixed finite element method combining with expanded mixed element method are discussed for a class of second-order pseudo-hyperbolic equations. The methods possesses the advantage of mixed finite element while avoiding directly inverting the permeability tensor, which is important especially in a low permeability zone. Depended on the physical quantities of interest, the methods are discussed. The existence and uniqueness of numerical solutions of the scheme are derived and an optimal order error estimate for the methods is obtained.

Abstract: The compressional strength of sea ice is a key parameter to determine the interaction between ice cover and offshore structure. In this study, the discrete element model (DEM) with particle bonding function is adopted to model the sea ice compressional strength. The bonding strength is set as a function of the ice temperature and ice salinity, and their influences on sea ice compressional strength are observed. The simulated results are compared well with the physical experimental data. With the improvement of this DEM, the ice load and ice-induced vibration of offshore structure can be simulated.

Abstract: In this paper, authors focus on the influence during the using of USB2.0 Interface board in reading and/or writing radiation arisen from the electromagnetic interference and provide some suggestions. This work employs two typical common using device, WIREWOUND filter and multilayer filter under the environment of the resistance of 90 ohm and 180 ohm to execute the analysis of the electromagnetic interference measurement. Numerous simulations have been made and obtain some successful results.

Abstract: To solving the problem that there had been too many undetermined parameters in the fuzzy control rules, it presented a simplified Takagi-Sugno, namely T-S, fuzzy reasoning method. It reduced the parameters of the IF-THEN rules greatly. In addition this paper also improved the genetic algorithm on the analysis of the prior genetic algorithm, by which the global optimal parameters of the controller can be found easily and quickly thus the control rules can be amended and perfected. The simulation results show that the improved genetic algorithm can find the optimal parameters at a high speed and the optimized T-S fuzzy controller can obtain an excellent control performance.

Abstract: A model for size dependent vacancy formation energy of nanosolids (nanoparticles, nanowires and nanofilms) has been developed by the consideration of their surface free energy. It is found that the vacancy formation energy of nanosolids decreases with the decrease of size. The relative variation of vacancy formation energy of nanoparticles, nanowires and nanofilms to bulk value at specified size follows 3:2:1. Furthermore, vacancy formation energy of nanosolids changes linearly with the reciprocal of size. The present results agree well with the predictions of BOLS and ECN theory.

Abstract: Aiming at improving localization accuracy in Wireless Sensor Networks (WSN) based on Least Square Support Vector Regression (LSSVR), making LSSVR localization method more practicable, the mechanism of effects of the kernel function for target localization based on LSSVR is discussed based on the mathematical solution process of LSSVR localization method. A novel method of modeling parameters optimization for LSSVR model using particle swarm optimization is proposed. Construction method of fitness function for modeling parameters optimization is researched. In addition, the characteristics of particle swarm parameters optimization are analyzed. The computational complexity of parameters optimization is taken into consideration comprehensively. Experiments of target localization based on CC2430 show that localization accuracy using LSSVR method with modeling parameters optimization increased by 23%~36% in compare with the maximum likelihood method(MLE) and the localization error is close to the minimum with different LSSVR modeling parameters. Experimental results show that adapting a reasonable fitness function for modeling parameters optimization using particle swarm optimization could enhance the anti-noise ability significantly and improve the LSSVR localization performance.

Abstract: The structural and electronic properties of graphite-like C₇N compound have been calculated by using first-principles pseudopotential density functional method for ten possible C₇N configurations, which are deduced from graphite and hexagonal boron nitride unit cell. The calculated total energy results show that the configuration C₇N-I with AA stacking sequence along the c-axis based on hexagonal BN structure has been shown to be the most stable structure. From the calculated electronic band structures and electron density of states, the monolayer and bulk phase of C₇N are expected to show insulating and metal states, respectively. The graphite-like C₇N phases have been predicted to be a stable phase at ambient conditions by formation energy and elastic constant calculations. A critical pressure of about 41 GPa is expected for a synthesis of cubic C₇N phase from this graphite-like C₇N.

Abstract: a Design Concept of Piecewise Variable Wall Thickness of Radome Is Proposed to Simulate the Radome which Has Variable Wall. the Paper Calculates the Far Field of a Medium-Size Radome in the Case of Piecewise Variable Thickness by Three Methods as Follows: Method of Moment (MOM), Multilevel Fast Multipole Method (MLFMM) and Physical Optics& the Method of Moments (PO/MOM) Respectively. after Comparing the Results, we Find that the PO/MOM Method Have the Superiority in Simulation of Radome’s Electromagnetic because it’s More Accuracy and Less Memory Consuming than the other Two Methods. Also it Proves the Feasibility of the Design Concept of Piecewise Variable Thickness for Radome.