Applied Mechanics and Materials Vols. 130-134

Abstract: Current symbolic execution is challenged by its ability to deal with loops. The case gets worse for loops manipulating recursive data structures. In this paper, we extend classic symbolic execution techniques for error detection of programs manipulating lists in loops. The idea is to enhance the symbolic execution with the utilization of quantitative aspect of the shape, and to construct the exit state of the loop. The exit state is constrained by a set of numeric constraints containing normal symbolic variables in programs and instrumented symbolic variables on the shapes. A prototype tool has been implemented and experiments are conducted on some commonly used list manipulating programs.

Abstract: Micro-grid is next generation of distribution system. The paper mainly investigates fault diagnosis issue of Micro-grid by using advanced Petri net technology. The paper puts forward diagnosis model of micro-grid based on Timed-colored Petri Net embedded object-oriented. The approach encapsulates each protection information, the associated breaker information and electrical components information and creates corresponding database tables. When the protection or breaker action occurs, through the means of communication to obtain the corresponding action information, use protection information as the keyword to search the database table to read the records and pass the record which has been encapsulated into object to the micro-grid diagnosis sub-module. The paper raises three delay levels, by adding time delay to achieve the priority of the corresponding logic. At last, example and verification show that Fault Diagnosis of Micro-grid based on Timed-Colored Petri Net (T-CPN) is valid.

Abstract: Many studies indicated that ADF test is very sensitive to different leg length selection models. Based on Hall, and Ng, Perron’s works, this article simulates a more general ARIMA(0,1,q) process and compares the influence of different selection methods to the size and power of the ADF test. Finally, it is proved that the Modified Information Criteria always shows a more proper size and the General to Special Criteria has more robust ADF test properties.

Abstract: Matrix exponential computstion is a difficulty thing when the order of the matrix get big and big after discretion. When we use Lie group method to get numeric solution of a differential equation, we often face this problem.Li group method is a kind of prosperous method, its basic ideas is to keep the numeric solution in a manifold which is less than the Euclid space while bigger than the analytic solution manifold, so we can get more exact numeric solution than other method. So we discussed the generalized polar decompositions method for matrix exponential.

Abstract: As for the problem of numerical simulation oflaser propulsion of three dimensions and multi-sub domains, the domain decomposition strategy based on message passing mechanismis applied in this paper to realize parallelization. The cell-centered finite volume scheme is performed to solve Euler equation. A five-step Runge-Kutta scheme of explicit integral model is used for time advancement. The spatial discretization of inviscid fluid is estimated byhigh-order Godunov-type scheme. We test some different examples on a cluster system and the results show the smallest number of speedup is more than 5.19 when the degree of parallelism is 8. In a word, parallel computation is an inevitable choice to achieve the aim of accelerating the study of the mechanism of laser propulsion.

Abstract: Progressive-edge-growth (PEG) algorithm is one of the best known methods for constructing LDPC codes at short and intermediate block lengths, however, the codes directly designed by such algorithm has high encoding complexity, especially for q-ary LDPC codes, encoding complexity increases with the increase of q value rapidly, which hinder the development of q-ary LDPC code’s implementation seriously. To such problem, the paper presents a improved method based on PEG algorithm which can be encoded by the iterative encoding algorithm with the liner operation complexity. The simulation results indicate: Though the error correcting capability of irregular q-ary LDPC codes constructed by the proposed methods in the paper is basically identical with the codes constructed by the PEG algorithm, but the powerful advantage makes it be easily implemented by the hardware .

Abstract: The computation and evaluation of color difference for images is a hot topic. In order to explore the calculation method of evaluating color difference sensation for similar images, 68 pairs of test images were made, which were made from ISO SCID 400 color images by altering their lightness and chroma respectively to cause different color difference scales, and tested by psychophysical experiment. The experiment results showed that the calculated color difference by each formula had a relation to the color difference sensation and the color difference formulae were optimized based on the experimental data.

Abstract: As one index of product certification for vehicle tire, rolling resistance is difficult to measure. In order to evaluate feasibility of two test schemes for tire rolling resistance measuring equipment, a new approach to study rolling resistance was developed with displacement deformation. Establishment process of finite element testing model was introduced briefly. Using two test schemes separately, simulation analysis and numerical computation of tire rolling resistance were conducted by controlling the experimental parameters. The comparison results showed that angle test method was reasonable and displacement field response to load was good under different working conditions. Subsequently, change trends of simulation results and experimental data were contrasted. They all indicated that tire rolling resistance added as the load enhanced and the obtained conclusion was consistent with related theories. It was validated that angle test scheme was feasible for equipment development.

Abstract: End-hopping is a technique proposed in the study of active defense in network security. In this paper, core technology analysis is made to the conception of “End-hopping” based on the previous research of our group. And the formal description is put forward. Methods are discussed and comparative analysis is made to implement End-hopping for active defense.

Abstract: In order to improve the desulphurization efficiency of KR mixing method in the process of molten iron refining, the method of CFD was used to analyze the flow field in a stirring vessel. The Fluent software was adopted to simulate and analyze the internal flow rule in a 3D stirring vessel with the method of multiple reference frame approach, and the corresponding models of Euler two-phase flow fluid model and standard k-ε turbulence model were used. By comparing with the experimental result, the influence of important parameters of agitator on internal flow field in the stirring vessel, such as rotational velocity, immersion depth and impeller type was discussed, and the flow structure was analyzed as well.