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Research of Vortex Nucleation in Bose-Einstein Condensates
Li Ji,
Ren Yuan,
Shao Qiongling
Issue:
Volume 5, Issue 1, February 2017
Pages:
1-6
Received:
13 March 2017
Published:
15 March 2017
Abstract: Vortex nucleation is the key technology to realize quantum gyroscope in Bose-Einstein Condensates (BEC). Through mass investigation and research, the recent research status of vortex nucleation in Bose-Einstein Condensates is presented, the theory and experimentation about imprinting phase, rotating the potential trap and transferring the orbital angular momentum of a photon to generate BEC vortex are analyzed and compared in detail, furthermore, an improved method of rotating the potential trap to generate vortex is proposed. Quantum gyroscope based on BEC vortex has the potential advantages of realizing the ultra high sensitivity and small volume of quantum gyroscope. This paper aims to promote the development of quantum vortex gyroscope, which attracts extensive attention of domestic scholars.
Abstract: Vortex nucleation is the key technology to realize quantum gyroscope in Bose-Einstein Condensates (BEC). Through mass investigation and research, the recent research status of vortex nucleation in Bose-Einstein Condensates is presented, the theory and experimentation about imprinting phase, rotating the potential trap and transferring the orbital a...
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Research of Numerical Simulation on Perforation of Conical Nose Rigid Projectile into Alluminum Alloy Target
Issue:
Volume 5, Issue 1, February 2017
Pages:
7-11
Received:
13 March 2017
Published:
15 March 2017
Abstract: In this paper,the penetration and perforation process of the conical nose rigid projectile into alluminum alloy target were simulated numerically by using FEM. Two sets of the projectiles and targets in different sizes were used in calculation models. The first set took the same size as the tested projectile and target for comparison, the second set changed diameter of projectile to evaluate its influence on the perforation capacity. The residual velocity were obtained by using numerical simulation. The simulation results indicate that in the same conditions, the calculated residual velocity coincides approximately with the existing data. It shows the validity and exactness of the proposed model. The projectile with smaller diameter possess better perforation performance.
Abstract: In this paper,the penetration and perforation process of the conical nose rigid projectile into alluminum alloy target were simulated numerically by using FEM. Two sets of the projectiles and targets in different sizes were used in calculation models. The first set took the same size as the tested projectile and target for comparison, the second se...
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Investigation on Application of Support Vector Machine Algorithm in the Experimental Simulation System for Mechanism Motion Reliability
Zhang Tong,
Li Sen,
Qiao Jia-dong
Issue:
Volume 5, Issue 1, February 2017
Pages:
12-18
Received:
13 March 2017
Published:
15 March 2017
Abstract: The complexity of the mechanism brings great difficulty to the calculation of the mechanism motion reliability, and the computer simulation algorithm based on Monte Carlo method needs a great number of simulation. The further-development of LMS Virtual. Lab was carried out, and the least square support vector machine algorithm was used to construct the response surface proxy model. The PSO-GA algorithm is used to optimize the parameters and make the least square support vector machine own a better performance. For the coupling of multiple failure modes, the multiple response surfaces are combined to obtain the reliability of the system. The reliability calculation based on support vector machine algorithm is carried out for the crank slider mechanism and the cam swing bar mechanism, and the feasibility and efficiency of the method are verified by the Monte Carlo method.
Abstract: The complexity of the mechanism brings great difficulty to the calculation of the mechanism motion reliability, and the computer simulation algorithm based on Monte Carlo method needs a great number of simulation. The further-development of LMS Virtual. Lab was carried out, and the least square support vector machine algorithm was used to construct...
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Distributed Grid-Connected Photovoltaic (pv) Research on the Influence of Power Distribution Network Voltage
Issue:
Volume 5, Issue 1, February 2017
Pages:
19-24
Received:
29 March 2017
Published:
31 March 2017
Abstract: For the study of distributed grid-connected photovoltaic (pv) affect the quality of power distribution network voltage. Application Matlab respectively different access points in the access of distributed photovoltaic (pv) power distribution network, different capacity and power factor to carry on the simulation. Analysis the influence of distributed photovoltaic access to voltage quality. Results show that the closer it gets to the end of the line network position or and the greater the network capacity,the greater the influence of node voltage photovoltaic system. And the nearer the and node location of nodes affected by the more serious. Because of the photovoltaic system itself will absorb a certain amount of reactive power,so shall be the pv systems with a certain amount of reactive power compensation device. In order to meet the demand for reactive power. Thus the power factor of photovoltaic system is close to 1.
Abstract: For the study of distributed grid-connected photovoltaic (pv) affect the quality of power distribution network voltage. Application Matlab respectively different access points in the access of distributed photovoltaic (pv) power distribution network, different capacity and power factor to carry on the simulation. Analysis the influence of distribut...
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Research on Sparse Targets Detection Methods Based on GLRT in Non-Gaussian Clutter
Gu Xinfeng,
Yan Shuqiang,
Hao Xiaolin,
Huang Kun
Issue:
Volume 5, Issue 1, February 2017
Pages:
25-32
Received:
29 March 2017
Published:
31 March 2017
Abstract: For the problem of detecting range-spread target with spare scatterers in non-Gaussian clutter modeled as spherically invariant random vector(SIRV). Firstly, it is assumed that the number of the target scatterers is known and a generalized likelihood ratio test detector based on scatterers number (SN-GLRT) is proposed. Then a sparse scatterers target detector based on GLRT (SST-GLRT) is proposed for unknowing the number of scatterers. The detection statistic of the SSR-GLRT is the weighted sum of the detection statistic of the SN-GLRT. The SSD-SST-GLRT and the NSSD-SST-GLRT are proposed based on the density of the scatterers. The analytical expression relating false alarm probability to detection threshold is deduced and the CFAR property of the SSD-SST-GLRT and the NSSD-SST-GLRT is proved. The results show that the detection performance of NSSD-SST-GLRT is better than the NSDD-GLRT. The detection performance of the SSD-SST-GLRT is better than the SDD-GLRT when the number of scatterers is known. The robustness of the SSD-SST-GLRT is better than the MSDD when the number of scatterers is unknown.
Abstract: For the problem of detecting range-spread target with spare scatterers in non-Gaussian clutter modeled as spherically invariant random vector(SIRV). Firstly, it is assumed that the number of the target scatterers is known and a generalized likelihood ratio test detector based on scatterers number (SN-GLRT) is proposed. Then a sparse scatterers targ...
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Permanent Magnet Synchronous Motor Direct Torque Control Based on Stator Resistance Online Estimation
Du Xue,
Zhang Suying,
Jin Ji,
Zhao Peidi,
Liu Huixian
Issue:
Volume 5, Issue 1, February 2017
Pages:
33-39
Received:
11 April 2017
Published:
12 April 2017
Abstract: Permanent magnet synchronous motor direct torque control system is characterized by its fast, automatic control and so on. Based on the actual value and reference value of the motor control system, this article analysis the effect of the stator resistance variation on the performance of the system.A method to track stator resistance variation is proposed according to the effect of stator resistance deviation on stator flux and current vector.Based on the optimal reference value of the stator current vector, the stator resistance value is estimated on-line by using the angle between the electromagnetic torque and the stator flux; and the simulation studies results using Matlab/Simulink shows that the control method is very effective to improve the low-speed performance of the system, reduced torque ripple and improve system robustness.
Abstract: Permanent magnet synchronous motor direct torque control system is characterized by its fast, automatic control and so on. Based on the actual value and reference value of the motor control system, this article analysis the effect of the stator resistance variation on the performance of the system.A method to track stator resistance variation is pr...
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Research on Fast Soft Shadow Algorithm Based on 4D Rasterization
Issue:
Volume 5, Issue 1, February 2017
Pages:
40-47
Received:
11 April 2017
Published:
12 April 2017
Abstract: This paper introduces an algorithm that extends traditional 2D projection and rasterization to 4D space for fast soft shadow rendering. First, the rectangular area light source is seen as a point light source that translates with two degrees of freedom. As the point light source moving, the projections of the triangles and the output image samples on the projection plane are also moving. The locus of the projection is called the 4D projection. 4D projections are rasterized, and a conservative set of output image sample/triangle pairs can be obtained. The set is then examined to derive light mask for each sample. Since all potentially blocking triangles are considered, the algorithm is an accurate algorithm. And, the algorithm does not require any type of precomputation, so it supports fully dynamic scene. We have tested our algorithm on several scenes to render complex soft shadows accurately at interactive rates.
Abstract: This paper introduces an algorithm that extends traditional 2D projection and rasterization to 4D space for fast soft shadow rendering. First, the rectangular area light source is seen as a point light source that translates with two degrees of freedom. As the point light source moving, the projections of the triangles and the output image samples ...
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Range-Spread Target Adaptive Detector for Non-Gaussian Clutter
Gu Xinfeng,
Hao Xiaolin,
Liu Tongling,
Yang Ganlin,
Li Xinxing
Issue:
Volume 5, Issue 1, February 2017
Pages:
48-52
Received:
11 April 2017
Published:
12 April 2017
Abstract: This paper addresses range-spread target detection in non-Gaussian clutter modeled as spherically invariant random vector clutter (SIRV). A adaptive modified scatterer density dependent (AMSDD) detector based on clutter power is addressed for the problem that MSDD has detection loss when falsely estimating the number of scatterers. Firstly, it estimates the scatterers by the power of clutter. Then, the returns of target scatterers are used to compare with the threshold to determine whether the target is exist or not. Compare with the MSDD and the NSDD , the AMSDD, adaptively estimates the number of target scatterers according to the observations, which can improve performance and robustness of detector effectively.
Abstract: This paper addresses range-spread target detection in non-Gaussian clutter modeled as spherically invariant random vector clutter (SIRV). A adaptive modified scatterer density dependent (AMSDD) detector based on clutter power is addressed for the problem that MSDD has detection loss when falsely estimating the number of scatterers. Firstly, it esti...
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Investigation on the Microstructure and Mechanical Properties of Dissimilar Weld Joint for Inconel 617 Alloy and 12Cr Steel
Wang Peng,
Xu Huali,
Liu Xia
Issue:
Volume 5, Issue 1, February 2017
Pages:
53-58
Received:
11 April 2017
Published:
12 April 2017
Abstract: The Inconel 617 nickel base alloy and 12Cr steel were welded by auto-TIG welding method, the microstructure and mechanical properties of dissimilar weld joint were investigated. The results showed that the optimized TIG welding process could obtain no defect dissimilar weld joint. Characterization on the microstructure of the weld joint showed that the weld metal was the coarsed columnar crystal with the secondary precipitation phase distribution in interdendritic which was growth with each other and through the weld layers. HAZ of 12Cr consisted of coarse grain zone, fine grain zone, and carbides near the fusion line of Inconel 617 change obviously. The hardness distribution of welded joint showed that HAZ near 12 Cr steel existed tempered soften zone, the minimum hardness is 240 HV; hardness of weld was fluctuant, and the average hardness is about 330 HV because of the coarsed columnar crystal and the secondary precipitation phase distribution in interdendritic in weld; hardness of 617 side gradually reduced from the fusion line to the parent metal. Tensile test of the weld joint fractured at HAZ near 12Cr; the lowest value of impact energy test occurred at HAZ near 617. Mechanical properties test result showed that the performance can satisfy the requirements.
Abstract: The Inconel 617 nickel base alloy and 12Cr steel were welded by auto-TIG welding method, the microstructure and mechanical properties of dissimilar weld joint were investigated. The results showed that the optimized TIG welding process could obtain no defect dissimilar weld joint. Characterization on the microstructure of the weld joint showed that...
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Study on the Yoshida-Uemori Material Model of High-Tensile Steel Sheets by Shear Tests
Chih-Yi Chang,
Ming-Hsiung Ho
Issue:
Volume 5, Issue 1, February 2017
Pages:
59-68
Received:
20 April 2017
Published:
20 April 2017
Abstract: In this research, the Yoshida-Uemori material models for four kinds of high-tensile steel sheet were analyzed by shear tests. The Yoshida-Uemori (Y-U) material model is currently the most important model in the simulation of stamp forming high-tensile steel sheets. It can comprehensively describe the Bauschinger effect and strain hardening behavior of metal during severe plastic deformation. Several commercial simulation software have built-in Y-U material models such as DYNAFORM and Pam-Stamp. The experimental curves must be obtained by the cyclic tension and compression test, and then the Y-U material parameters can be calculated by the regression operation. However, the parameters of the Y-U material model are difficult to obtain because the cyclic tension and compression test of thin sheet is prone to buckling phenomenon. This study first discuss the transform relation between shear test and tensile test, and then the Y-U material model is established by cyclic shear tests to avoid buckling. LS-DYNA numerical simulations of the shear tests were used to verify the accuracy of the material models. Four kinds of high-tensile steel sheet produced by China Steel Corporation are discussed, including JSC1180Y, JSC980Y, JAC590R and JSC440P, which cover a wide range of strength of the stamping plate. It further confirmed that the proposed research method does work.
Abstract: In this research, the Yoshida-Uemori material models for four kinds of high-tensile steel sheet were analyzed by shear tests. The Yoshida-Uemori (Y-U) material model is currently the most important model in the simulation of stamp forming high-tensile steel sheets. It can comprehensively describe the Bauschinger effect and strain hardening behavior...
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Research on Feasibility of Large-scale New Energy Islanding Detection Scheme Based on Impedance Measurement
Issue:
Volume 5, Issue 1, February 2017
Pages:
69-76
Received:
20 April 2017
Published:
20 April 2017
Abstract: A lot of research has been done on islanding detection of photovoltaic(PV) power system. In these schemes, islanding can be detected by schemes based on convertor control. The range of these research is islanding occurs in a single power station or distributed generation system. However, experiments proof that islanding also occurs in large-scale wind farms. Classical islanding detection schemes such as active frequency drift scheme or reactive power disturbance scheme may not suitable to this situation due to the different parameter when islanding occurs in large-scale new energy power stations. Meanwhile, islanding detection scheme based on system impedance detecion is an ideal scheme to detect islanding in large-scale new energy power stations. However, reaearch on islanding detection scheme based on system impedance only compute the impedance of the outlet end of the convertor, in other words, in a single power station and overlook the problems when the scheme is applied to large-scale new energy power stations, such as power quality problem and signal attenuation problem and so on. This artical will analyze the feasibility of using system impedance to detect islanding in large-scale new energy power stations.
Abstract: A lot of research has been done on islanding detection of photovoltaic(PV) power system. In these schemes, islanding can be detected by schemes based on convertor control. The range of these research is islanding occurs in a single power station or distributed generation system. However, experiments proof that islanding also occurs in large-scale w...
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