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Peng K.,National University of Defense Technology | Hu F.,National University of Defense Technology | Zhang W.-H.,National University of Defense Technology | Zhou Z.,Jiangnan Industries Group Co.
Guti Huojian Jishu/Journal of Solid Rocket Technology | Year: 2015

Researd methods on aerodynamic characteristics of grid fin, were summarized in fields of experimental research, engineering prediction, and numerical simulation. Major aerodynamic characteristics of grid fin, latest geometrical configurations research progresses about curved grid fin and global & local swept grid fin, as well as application trends at home and abroad were discussed. Critical concerns about grid fin were analyzed in view of the bottleneck problems of design and application. ©, 2015, Journal of Solid Rocket Technology. All right reserved. Source

Huang Q.,Hunan University | Huang S.-D.,Hunan University | Chen Z.-Y.,Hunan University | Zhou T.-T.,Hunan University | And 3 more authors.
Dianji yu Kongzhi Xuebao/Electric Machines and Control | Year: 2014

In order to suppress the harmonic power and load disturbance effect to the DC bus voltage the condition that the PWM rectifier works with asymmetrical grid voltage, a new voltage control method was proposed based on variable structure active disturbance rejection control (VS-ADRC) theory. Combining variable structure control with active-disturbance rejection controller (ADRC), the variable structure active disturbance rejection controller was designed. In order to eliminate the perturbation to the system caused by current loop coupling and the harmonic composition in power transmission, VS-ADRC was used in positive and negative sequence current loop. The improved controller not only maintains the original features of ADRC, but also reduces the adjustable parameters, which makes it easy to parameter setting and makes control performance better. Simulation and experimental results show that this method can control the output voltage fast and not overshoot, and suppress the impact to the system caused by harmonics power in transmission and load changes effectively. Source

Wang E.,CAS Shenyang Institute of Automation | Wang E.,University of Chinese Academy of Sciences | Wang E.,Chinese Academy of Sciences | Zhu F.,CAS Shenyang Institute of Automation | And 6 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2013

The tracking convergent property is an important guideline for a reticle seeker. The tracking of the reticle seeker is driven by the period mean torque which is generated by the tracking signal. In this paper, the convergent property of the reticle seeker was analyzed and some significant conclusions were attained using series theory. The convergence of the tracking procession was affected by both the tracking coefficient and the phase bias δθ between the target location and the tracking signal. The convergent conditions and the convergent step function were also obtained. These conclusions are important for the design of the convergent tracking algorithm of the reticle seeker. Source

Yao C.,Jiangnan Industries Group Co. | Wang H.,Jiangnan Industries Group Co. | Liu X.,Control Iron and Steel Research Institute, China | Wang C.,Control Iron and Steel Research Institute, China | And 4 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

In order to refine grain of the T250 maraging steel cylindrical forging without Co as well as to ensure the performance of product, repeat cyclic heat and quench treatment experiment was carried out. The results show that the cyclic heat treatment with descending variable temperature can make the grain of T250 maraging steel after forging refine to a certain extent. The principle of the refined grain through the cyclic heat treatment is different from that of the common structural steel, which requires a little more holding duration to make to the microstructure re-crystallization. However, the function of refine grain through cyclic heat treatment is finite; henceforth, the precaution and control of the grain growth during forging cannot be neglected. © 2016, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved. Source

Yao C.,Jiangnan Industries Group Co. | Wang H.,Jiangnan Industries Group Co. | Zeng C.,Jiangnan Industries Group Co. | Lu B.,Jiangnan Industries Group Co. | And 2 more authors.
Proceedings of the International Astronautical Congress, IAC | Year: 2013

Some carbon-steel components (diamond block, slide block, and upper locking ring) of an aerospace product had found cracks one by one in their process. In order to guarantee the product's quality and, especially, ensure the security of astronauts, the cause of cracking had been investigated and analyzed. Given that the parts' material are not allowed to alternate, the original process technology has been improved through adopting oil hardening, mar-tempering, and inter-critical hardening to replace the original quench process of these components respectively, and adding stress relief process between some original machining procedures, which has finally solved the problem and guaranteed the quality and quantity of the production on schedule. The failure analysis and improved process showed that during the manufacturing process of above carbon-steel components, for preventing cracking, the technology should be optimized, and the quenching stress and grinding stress should be decreased as less as possible, and so does the residual stress. In the meantime, the bad impact on the quality of parts and components of product caused by the inclusion of raw material and the acid cleaning prior to electroplating also can not be ignored. Copyright © 2013 by the International Astronautical Federation. Source

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