Applied Mechanics and Materials Vols. 713-715

Abstract: The developmental situation of space welding technology home and abroad is introduced. Then it’s put forward that the designing scheme and the computer aided design (CAD) method of main focusing system of the domestic space electron beam gun with equal-diameter three-cylinder electrostatic single lens. The parameters calculation of the focusing system is completed through language C utilizing computer programming and a satisfying result is gotten.The result shows that electron beam current disperse focusing is less, and the beam section is less in the deflection magnetic field, the beam spot radius on the workpiece is about 0.6300mm at least, and can meet the requirement of the space welding and cutting.

Abstract: Based on the analysis of the transient process of the electric line’s developing ground fault, this paper applies the oppositely-directed travelling wave fault location method to fault location in distribution network. Simultaneously, this paper chooses proper wavelet generating functions to find the modulus maximum of oppositely-directed travelling waves and summarizes the methods and steps of this oppositely-directed travelling wave fault location. Finally, PSCAD/EMTDC is used to simulate the single-phase ground fault to verify the oppositely-directed travelling wave fault location method.

Abstract: In order to solve the issues of time synchronization that occurs in simultaneous measurement in power system, designing a GPS clock synchronization method based on time different compensation which can guarantee high-precision whether the GPS satellites are locked or not. The paper provides the basic idea describe and the overall hardware and software design. Simulation results show that the scheme provides second pulse with error in 0.8μs when GPS is locked and provides second pulse with error in 7μs when GPS is unlocked for 12 hours. The accuracy is better than the existing references.

Abstract: Currently the IEC 61850 standard for the transmission line has not been established a complete data model, restricting the development of smart grid. This paper is based on the study of the IEC 61850 standard, and information on major transmission lines were analyzed in detail, in accordance with the standard information of transmission line model based on IEC 61850 was established.

Abstract: Wind and solar energy are considered as the most representatively new and renewable energy. At present, wind and solar power generation systems is playing unique role in China's solar and wind energy resource-rich region, which arise more requirements to manage and monitor the system. Based on the MCGS (Monitor and Control Generated System) configuration software development platform, the monitoring system of experimental wind/solar hybrid system is designed, including controller driver loading, real-time database establishment, device configuration, animation production and other configuration. The developed software can better monitor and control the experimental wind/solar hybrid system.

Abstract: To improve the accuracy of load forecasting and cope with the challenge of single computer’s insufficient computing resource, a short-term distributed load forecasting model based on LSSVM optimized by IPPSO is proposed. Uncertain parameters are optimized by improved parallel particle swarm algorithm which runs on the Spark on Yarn memory computing platform. The real load data provided by EUNITE is used, and experiments and analysis are conducted on an 8-node cloud computing platform. The results show that the accuracy of the algorithm proposed by our paper is better than the traditional functional networks algorithm, the efficiency of the algorithm is better than MR-OSELM-WA, and the algorithm has good ability of parallelization.

Abstract: A mechanism that the backoff exponent changes dynamically was proposed aiming at the poor performance of backoff algorithm in IEEE 802.15.4 MAC protocol. The algorithm could adjust the initial backoff exponent according to the previous transmission status and the backoff exponent. A Markov chain model for the algorithm was established and the mathematical derivation for the model was carried out. The theoretical analysis and simulation results show that the model increases the channel access probability and system throughput. The optimized algorithm improves the performance of LOWPAN effectively.

Abstract: Due to the serious problem of wireless 3-Dimensional localization technology affected by geographical conditions and other signal jamming, we proposed a new weighted 3-Dimensional localization algorithm based on TDOA-AOA. In this new algorithm, we obtained two groups of 3-Dimensional projected coordinate values of every test point using joint algorithm of TDOA and AOA. Then after weighted scaling, we got the localization coordinate of the point. It is proved by multiple sets of simulation experiments that this algorithm with data weighting can effectively reduce the localization error caused by the environmental interference, and thus ensure the accuracy and effectiveness of the results.

Abstract: A large number of harmonic is mainly produced by with the discrete variable frequency soft starter. The harmonic during the motor soft starting is characterized by the high energy consumption and signal interference. Therefore, harmonic analyzing and filtering of motor discrete variable frequency soft starter is presented in this paper to achieve low energy consumption and ensure the motor soft starting stably. The following works have been done in the study: introduce the reason of harmonics appearance, analyze the harmonic, and present the filtering approach. The motor soft starter developed with this filtering approach has been successfully applied to filter out harmonic and to improve the starting performance when the motors draw the heavy-loads. It saves energy, stabilize the voltage of the power supply network.

Abstract: Mobile radio channel models are essential for the development, evaluation and test of current mobile radio communication systems and also crucial for the realization of the future systems. Nakagami-m distribution is important for channel modeling in mobile communication. It can repeat system tests in the development, design, or test laboratory. In this study, we make a simulation study of the Nakagami-m distribution. We focus on study the PDF of Nakagami-m distribution under different values ofand, we also simulate the SER Vs.SNR over Nakagami-m fading channel for QPSK