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Coordinated standoff tracking of moving targets using differential geometry

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第4期15卷 284-292页

作者： Zhi-qiang SONG Hua-xiong LI Chun-lin CHEN Xian-zhong ZHOU Feng XU Department of Control and system Engineering School of Management and Engineering Nanjing University Department of Information Suzhou Institute of Trade and Commerce No. 207 research Institute China North Industries Group Corporation

This research is concerned with coordinated standoff tracking, and a guidance law against a moving target is proposed by using differential geometry. We first present the geometry between the unmanned aircraft(UA) and the target to obtain the convergent solution of standoff tracking when the speed ratio of the UA to the target is larger than one. Then, the convergent solution is used to guide the UA onto the standoff tracking geometry. We propose an improved guidance law by adding a derivative term to the relevant algorithm. To keep the phase angle difference of multiple UAs, we add a second derivative term to the relevant control law. Simulations are done to demonstrate the feasibility and performance of the proposed approach. The proposed algorithm can achieve coordinated control of multiple UAs with its simplicity and stability in terms of the standoff distance and phase angle difference.

关键词： Unmanned aircraft Standoff tracking Differential geometry Coordinated control

Tracking algorithm of BPSK signal in low bit SNR and high dynamic scenarios

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Journal of Beijing Institute of Technology 2015年第1期24卷 118-127页

作者：王鹏陈国瑛 Beijing Institute of Electronic system Engineering the Second Academy of China Aerospace Science and Industry corporation

A new tracking algorithm is proposed aiming at the tracking problem in low bit signal-to- noise ratio （i. e. , Eb/N0 ） scenarios, in which the bit clock regenerated by bit synchronization loop decides loop update moment. The double frequency processing and non-coherent accumulation tech- nologies are applied to eliminate the impact of data polarity inversion, and then long time accumula- tion improves the input signal-to-noise ratio of discriminator. The frequency locked loop and phase locked loop constitute a carrier loop in parallel, which can meet the high dynamic demands. The ef- fectiveness of this algorithm has been corroborated by theoretical analysis, simulation and measure- ments, and the new tracking algorithm has been used in an aerospace engineering project successfully.

关键词： tracking double frequency processing non-coherent low bit signal-to-noise ratio

Deterministic and Stochastic Simulators for Non-Isotropic V2V-MIMO Wideband Channels

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China Communications 2018年第7期15卷 18-29页

作者： Yiran Li Xiang Cheng Nan Zhang State Key Laboratory of Advanced Optical Communication systems and Networks School of Electronics Engineering and Computer Science Peking University Wireless Algorithm Department Product Research and Development System ZTE Corporation

In this paper, we consider a novel two-dimensional(2D) geometry-based stochastic model(GBSM) for multiple-input multiple-output(MIMO) vehicle-to-vehicle(V2V) wideband fading channels. The proposed model employs the combination of a two-ring model and a multiple confocal ellipses model, where the signal is sum of the line-of-sight(Lo S) component, single-bounced(SB) rays, and double-bounced(DB) rays. Based on the reference model, we derive some expressions of channel statistical properties, including space-time correlation function(STCF), Doppler spectral power density(DPSD), envelope level crossing rate(LCR) and average fade duration(AFD). In addition, corresponding deterministic and stochastic simulation models are developed based on the reference model. Moreover, we compare the statistical properties of the reference model and the two simulation models in different scenarios and investigate the impact of different vehicular traffic densities(VTDs) on the channel statistical properties of the proposed model. Finally, the great agreement between simulation models and the reference model demonstrates not only the utility of simulation models, but also the correctness of theoretical derivations and simulations.

关键词： vehicle-to-vehicle wideband channels simulation model statistical properties

Modeling porous structure of oil-pressboard interface and its effect on electric field distribution

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Journal of Central South University 2015年第1期22卷 338-343页

作者：司马文霞姜赤龙毛文奇唐信 State Key Laboratory of Power Equipment & system Security and New Technology(Chongqing University) State Grid Hunan Electric Power corporation Maintenance Company State Grid Hunan Electric Power corporation

The oil-pressboard insulation is a typical composite insulation system widely used in the design and manufactory of large power apparatus. The implement of oil-pressboard insulation may lead to surface electrification and discharge at the interface under certain condition. It is of significant importance to take an insight into the phenomenon occurring at the interface. Through experiment, the pressboard is found as a porous material. The interface changes abruptly from bulk pressboard to the bulk oil as a result of the porous structure. A new model is proposed which divides the interface into bulk oil region, transition region, and bulk pressboard region. The width of the transition region is decided according to the microtome figure. The effective permittivity of the transition region is calculated using a new model based on fractal theory. The model is validated and compared with previous calculation model. The effect of the existence of transition region on the electric field distribution is discussed.

关键词： oil-pressboard interface transition region effective permittivity fractal electric field distribution

Hydrogen Incorporation in Crystalline Jadeite: Insight from First Principles Calculations

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Acta geologica Sinica(English Edition) 2016年第3期90卷 939-945页

作者： ZHANG Xiaoling FAN Xiaoyu MENG Dawei WU Xiuling LIU Weiping Faculty of Materials Science and Chemistry Engineering Research Center of Nano-Geo Materials of Ministry of Education China University of Geosciences

Hydrogen incorporation is critical for explaining defect energies, structure parameters and other physical characteristics of minerals and understanding mantle dynamics. This work analyzed the hydrogen complex defects in jadeite by the plane-wave pseudo-potential method based on density functional theory, and optimized the atomic positions and lattice constants in all configurations （different defective systems）. Incorporation mechanisms considered for hydrogen （H） in jadeite include：（1） hydrogen incorporating with the 02 site oxygen and coexisting with M2 vacancy; （2） one H atom combined with an AI atom replacing Si in tetrahedron; （3） 4H atoms directly replacing Si in tetrahedron and （4） 3H atoms replacing Al on the M1 site. The four incorporation mechanisms mentioned above form the corresponding VNa-Hi, Alsi-Hi, Vsi-4Hi and VAr3Hi point defects. The molecular dynamics simulation to the ideal, VNa-Hi, Alsi-Hi, Vsi-4Hi and VAr3Hi point defects under the P-T conditions of 900 K, 2 GPa, the Vsa-Hi and Alsi-Hi point defects under different pressures at T = 900 K, and Alsj-Hj point defects under different temperatures at P = 3 GPa was performed to examine the preferential mode of hydrogen incorporation in jadeite by means of first-principles calculations. The calculations show that the averaged O-H bond-length in the hydrogen point defects system decreased in the order of Alsi-Hi, VNa-HI, Vsl-4Hf and VAI-3Hi. VNa-HI complex defects result in a contraction of the jadeite volume and the presence of Alsi-Hi, Vsi-4H~ and VAI-3Hi defects could increase the superceli volume, which is the most obvious in the VAt-3Hi defects. The energy of formation of Also-HI and VA[-3HI complex defects was much lower than that of other defect systems. The VAI-3Hi defects system has the lowest energy and the shortest O-H bond-length, suggesting that this system is the most favorable. The analytical results of vacancy formation energy, O-H bond- length, and the stability of the hydrogen defec

关键词： jadeite first principles calculations hydrogen point defects hydrogen incorporation

Feature analysis on US military aircraft engine advanced technology programs

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航空动力学报 2014年第7期29卷 1701-1709页

作者： LIANG Chun-hua SUN Ming-xia LIU Hong-xia Shenyang Engine Design and research Institute Aviation Industry Corporation of China

US military aircraft engine advanced technology programs were overviewed and analyzed from light weight gas generator(LWGG)program initiated in 1960 sthrough integrated high performance turbine engine technology(IHPTET)program started in 1980 s,then to versatile affordable advanced turbine engine(VAATE)*** features and trends were summarized and concluded by literature statistics method,such as teams based on closely corporation among government,industries and academics,goals oriented with national defence strategies and weapon system development requirements,engineering manufacture and development including all relative disciplines and areas,verification measured by technology readiness level,the application extending to military aircraft engine,civilian engine,gas turbine and space vehicle,*** experience and lessons obtained can provide reference and guide for technology research and engineering manufacture and development of military aircraft engines in the world.

关键词： aircraft engine military aircraft engine advanced technology program technology corporation multi-discipline development technology verification

The Godson Processors:Its research,Development,and Contributions

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Journal of Computer Science & Technology 2011年第3期26卷 363-372页

作者：胡伟武高燕萍陈天石肖俊华 Key Laboratory of Computer system and Architecture Chinese Academy of Sciences Loongson Technologies corporation Limited Graduate University of Chinese Academy of Sciences

The Godson project with an R＆D history of 10 years is an independent national program of China that aims at developing advanced microprocessor technologies based on fundamental research and commercialization of the chip technology. We will give a comprehensive presentation of the Godson project, including its history, technical roadmaps, and several unique technical merits.

关键词： IT industry CPU research and development Godson microprocessor XPU system on chip

Multi-Objective Load Distribution Optimization for Hot Strip Mills

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Journal of Iron and Steel research International 2013年第2期20卷 27-32,61页

作者： JIA Shu-jin LI Wei-gang LIU Xiang-hua DU Bin Department of Automation and Key Laboratory of system Control and Information Processing Shanghai Jiao Tong University Automation Division of research Institute Baosteel Group Corporation College of Information Science and Engineering Northeastern University research Institute of Science and Technology Northeastern University

Load distribution is a key technology in hot strip rolling process, which directly influences strip product quality. A multi-objective load distribution model, which takes into account the rolling force margin balance, roll wear ratio and strip shape control, is presented. To avoid the selection of weight coefficients encountered in single objective optimization, a multi-objective differential evolutionary algorithm, called MaximinDE, is proposed to solve this model. The experimental results based on practical production data indicate that MaximinDE can obtain a good pareto-optimal solution set, which consists of a series of alternative solutions to load distribution. Decision-makers can select a trade-off solution from the pareto-optimal solution set based on their experience or the importance of ob- iectives. In comparison with the empirical load distribution solution, the trade-off solution can achieve a better per- formance, which demonstrates the effectiveness of the multi-objective load distribution optimization. Moreover, the conflicting relationship among different objectives can be also found, which is another advantage of multi-objective load distribution optimization.

关键词： hot strip mill load distribution multi-objective optimization

Numerical simulation of wellbore and formation temperature fields in carbonate formations during drilling and shut-in in the presence of lost circulation

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Petroleum Science 2014年第2期11卷 293-299页

作者： Pan Baozhi Li Ding Chen Gang Wang Qincong Ma Lixin Liu Sihui College of geo-Exploration Science and Technology Jilin University Xi'an research Institute of China Coal Technology & Engineering Group Corp

Temperature curves reflect geothermal gradients and local temperature anomalies, thus providing a new understanding of the underground reservoir conditions. When encountering caverns or fractures and fissures during drilling, lost circulation may occur and result in a change to the original formation temperature field, and in severe cases, even the conventional open hole well logging data cannot be obtained. This paper uses finite element analysis software COMSOL to establish a heat transfer model for the wellbore/reservoir formation system during drilling and shut-in in the presence of lost circulation, and a case study is made in a carbonate reservoir in the Tahe oilfield. On the basis of the above, we analyze the temperature distribution in the leakage zone, and the studies have shown that the leakage and petrophysical properties have an impact on the temperature of the wellbore and formation, hence we can estimate the reservoir permeability using the temperature data. In addition, the determination of the temperature recovery time after some drilling fluids have leaked into the formation will help in recognizing the subsurface temperature field of the carbonate formation correctly, thus enhancing production logging interpretation accuracy and improving the understanding of later measurements.

关键词： Temperature field numerical simulation finite element drilling fluid invasion leakage