Wuxi Radio and Television University

Wuxi, China

Wuxi Radio and Television University

Wuxi, China
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Zheng Y.,Wuxi Radio and Television University | Zheng Y.,University of Science and Technology Beijing | Wang Z.,Wuxi Radio and Television University
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2012

The dendrite structure characteristics, mechanical properties and forming conditions of Al-35La alloy prepared by directional solidification were investigated. The results show that the dendrite structure in Al-35La alloy obtained by directional solidification exhibits discontinuous and periodic two-phase morphology along the main body. The mechanic properties testing shows that the samples obtained exhibit higher compression strength and hardness. Formation mechanism of the periodic two-phase dendrite structure in Al-35La alloy was described. Convection with a certain intensity will take off crystallization latent heat in the liquid by promoting solute exchanging during nucleation and growth of dendrite. Therefore, it is considered that the convection with a certain intensity will promote the alternately nucleation and growth of two phase in the liquid of Al-35La alloy, resulting in the formation of periodic two-phase dendrite structure in the alloy.


Zhang T.-Y.,Wuxi Radio and Television University
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

The Tanner graph of long LDPC codes usually has no loops and LLR BP algorithm is the best soft-decision decoding algorithm. But the Tanner graph of short LDPC codes usually has loops, so the information within variable nodes isn't mutually independent and the decoding performance of LLR BP algorithm will decrease. A modified LLR BP algorithm is proposed. Parameters of the proposed algorithm are calculated according to probability theory and minimum mean square error rule. The simulation results show that the LDPC decoding performance of modified LLR BP algorithm is more effective than that of LLR BP algorithm, Normalized BP algorithm and Offset BP algorithm.


Zhang T.-Y.,Wuxi Radio and Television University
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

It is difficult to build an accurate model by using traditional predictive control algorithm for the nonlinear system of strong time delay. So its control accuracy is not high. A nonlinear model predictive control (NMPC) algorithm based on least squares support vector machine (LS-SVM) is proposed. The off-line predictive model of nonlinear system is established by LS-SVM to train a sequence data of input and output. Then the whole rolling optimization procedure is finished by the algorithm of quantum delta-potential-well-based particle swarm optimization (QDPSO). The simulation results show that the control quality of NMPC based on LS-SVM is more effective than that of dynamic matrix control (DMC).


Zhang T.-Y.,Wuxi Radio and Television University
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

Reed-Solomon (RS) code is widely used in the field of communication, of which the most important is solving key equation. Long division of polynomial is used to solve key equation in traditional Euclidean algorithm. The degree of polynomial needs judging. Moreover, quotient formula and remainder formula must be calculated by iterative computation, which will cause the complexity of hardware circuit and decrease the decoding speed. A modified Euclidean algorithm is proposed by the related knowledge of matrix theory. It does not need to judge the degree of polynomial and iterative computation, and can calculate quotient formula and remainder formula quickly. The proposed algorithm can decrease the complexity of decoding and improve the decoding speed. The simulation results show that the proposed algorithm can achieve the effects of correct decoding by FPGA simulation in the software of VCS.


Zhang T.-Y.,Wuxi Radio and Television University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

A current sharing control method of paralleled Buck converter is proposed based on backstepping method in continuous conduction mode of inductor current. On the basis of state equation of paralleled Buck converter, a state which expresses the integration of error between inductor currents is introduced and then the state vector is expanded and the expanded state equation is obtained. For the proposed state equation, according to the principle of backstepping method, the backstepping current sharing control law of paralleled Buck converter is designed. The simulation results show that the backstepping current sharing control can achieve good current sharing effect and has stronger robustness than the automatic current sharing control.


Zhang T.-Y.,Wuxi Radio and Television University
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

Traditional coordinate rotation digital computer (CORDIC) algorithm can realize the calculation of many complex functions by look-up table and many multipliers, which will result in the complexity of hardware circuit and decrease the operation speed. A modified CORDIC algorithm is proposed in rotation mode. It needn't look-up table and scale factor correction and can realize the calculation of many complex functions only by simple shift and addition-subtraction operation, which can reduce the cost of hardware and improve operational performance. Finally, the proposed algorithm is applied to the Givens rotation of QR_RLS adaptive equalization algorithm, which completes QR-decomposition of input data matrix and realizes adaptive equalization effect.


Zheng Y.,University of Science and Technology Beijing | Zheng Y.,Wuxi Radio and Television University | Wang Z.,University of Science and Technology Beijing
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2010

Al-35La alloy was prepared by different casting molds, such as permanent mold, graphite mold and sand mold with vacuum melting furnace, and its microstructure and mechanical properties were examined. The results show that microstructure of the Al35La alloys prepared by different casting molds are composed of periodic two-phase dendrites. The hardness and relative compressibilities of the alloy prepared by different casting mold are approximately the same. Alloy exhibits a higher compression strength with 10% relative compressibility , which is attributed to discontinuous distribution of AIH La11 phase in the alloy refining grain size. Furthermore, the forming mechanism of the Al11 La3 phase was described.


Zhang T.-Y.,Wuxi Radio and Television University
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010

Traditional coordinate rotation digital computer (CORDIC) algorithm can realize QR-decomposition of matrix by look-up table and many multipliers, which will result in the complexity of hardware circuit and decrease the operation speed. Moreover the angle range which can be calculated is also limited. According to the defects of traditional CORDIC algorithm, a modified CORDIC algorithm is proposed in vectoring mode. It needn't look-up table and scale factor correction and can realize QR-decomposition of matrix only by simple shift and addition-subtraction operation, which can reduce the cost of hardware and improve operational performance. The proposed algorithm is suitable for all the rotation angles by repeated iteration and domain transformation. Finally, the proposed algorithm is applied to the QR algorithm of V-BLAST receiving system, which realizes low complexity decoding effect.

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