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Pulse signal detection in cognitive UWB system

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The Journal of China Universities of Posts and Telecommunications 2012年第3期19卷 74-79页

作者： SONG Xiao-ou XIANG Xin BI Du-yan DENG Yong Engineering College Air Force Engineering.UniversityXi'an 710038China

According to the problem of cognitive ultra wide-band （UWB） spectrum sensing, a novel UWB pulse signal detection algorithm based on cumulative sum （CUSUM） test is proposed in this paper. Based on the analysis of the existing spectrum sensing schemes for cognitive UWB system, some obvious facts are obtained that it is difficult to detect UWB pulse signal with conventional spectrum sensing schemes, due to its low average signal to noise ratio （SNR）, large bandwidth, and low duty ratio. In this paper the detection algorithm of signal distribution change, which is application of CUSUM test, is considered to be applied to cognitive UWB spectrum sensing. But CUSUM test request that the pre-change and the post-change distributions are i.i.d, which cannot be satisfied in the detection process of UWB pulse signal. Since there are two time domain descriptions on UWB pulse signal, namely one contains only noise and the other one contains pulse signal plus noise, the existing detection algorithm of signal distribution change cannot be directly applied to detect UWB pulse signal. Hence the uniform probability density function expression of UWB pulse signal is first deduced, then CUSUM test is applied to cognitive UWB spectrum sensing. The proposed algorithm is a time sequential detection algorithm, with low complexity and minimal detection delay, which is suitable to detect the low duty ratio signal. Its performance is evaluated through theoretical analysis and numerical simulations. It is shown that this algorithm outperforms the conventional energy detection algorithm and conquers SNR wall phenomenon.

关键词： cognitive UWB (CUWB) spectrum sensing pulse signal CUSUM

Model of Airflow Field on the Deck for Shipborne Helicopter Flight Dynamics Analysis

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第5期34卷 567-577页

作者： Hu Guocai Xu Guang Wang Yunliang Liu Shuyan Department of Airborne Vehicle Engineering Naval Aeronautical and Astronautical University Yantai 264001 P.R. China Troops 92074 PLA Ningbo 315000 P. R. China

For the research of helicopter/ship dynamic interface,the method of combining steady flow and stochastic flow is adopted to establish a flow field model applied to the flight dynamics analysis of shipborne *** steady flow is calculated by computational fluid dynamics(CFD)method,while the stochastic flow is composed of the compensation velocity derived from ship motion and turbulence above the *** accuracy of the proposed flow field model is verified by comparing the helicopter response in the proposed flow field with the results calculated by US Army′s Military Specifications(MIL)model which is commonly used in ***,it also shows the proposed flow field model is more appliable to flight dynamics analysis of shipborne *** that the basis,ship deck flow field is simulated at different sea conditions by adjusting the wind speed on the deck,mother ship movement and shipboard turbulence,*** helicopter angular rate response is *** results show that the difference of dynamic stability between helicopter′s roll and pitch leads to the facts that the influence of above factors on the helicopter′s roll angular rate response is greater than that of pitch angular rate,that the frequency and amplitude of mother ship roll motion are much greater than those of pitch motion,and that the disturbance caused by roll motion on the air has greater influence on the helicopter *** shipboard turbulence is the main disturbance factor that influences helicopter flight stability and its intensity determines the amplitudes of angular rate response.

关键词： shipborne helicopter flight dynamics airflow field on the deck time-space characteristics sea condition

Nonlinear response analysis and experimental verification for thin-walled plates to thermal-acoustic loads

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Chinese Journal of Aeronautics 2017年第6期30卷 1919-1930页

作者： Yundong SHA Jian WANG Liaoning Key Laboratory of Advanced Test Technology for Aeronautical Propulsion System Shenyang Aerospace University Shenyang 110136 China

For large deflection strongly nonlinear response problem of thin-walled structure to thermal-acoustic load, thermal-acoustic excitation test and corresponding simulation analysis for clamped metallic thin-walled plate have been implemented. Comparing calculated values with experimental values shows the consistency and verifies the effectiveness of calculation method and model for thin-walled plate subjected to thermal-acoustic load. Then this paper further completes dynamic response calculation for the cross reinforcement plate under different thermalacoustic load combinations. Based on the obtained time-domain displacement response, analyses about structure vibration forms are mainly focused on three typical motions of post-buckled plate,indicating that the relative strength between thermal load and acoustic load determines jump forms of plate. The Probability spectrum Density Functions（PDF） of displacement response were drawn and analyzed by employing statistical analysis method, and it clearly shows that the PDF of postbuckled plate exhibits bimodal phenomena. Then the Power Spectral Density（PSD） functions were used to analyze variations of response frequencies and corresponding peaks with the increase of temperatures, as well as how softening and hardening areas of the plate are determined. In the last section, this paper discusses the change laws of tensile stress and compressive stress in pre/post buckling areas, and gives the reasons for N glyph trend of the stress Root Mean Square（RMS）.

关键词： Buckling Experimental verification Nonlinear response Power spectral density Probability spectrum densitySnap-through Thermal-acoustic load Thin-walled structure

Civil aircraft fault tolerant attitude tracking based on extended state observers and nonlinear dynamic inversion

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Journal of Systems Engineering and Electronics 2022年第1期33卷 180-187页

作者： MA Xinjian LIU Shiqian CHENG Huihui School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

For the problem of sensor faults and actuator faults in aircraft attitude control,this paper proposes a fault tolerant control(FTC)scheme based on extended state observer(ESO)and nonlinear dynamic inversion(NDI).First,two ESOs are designed to estimate sensor faults and actuator faults ***,the angular rate signal is reconstructed according to the estimation of sensor ***,in angular rate loop,NDI is designed based on reconstruction of angular rate signals and estimation of actuator *** FTC scheme proposed in this paper is testified through numerical *** results show that it is feasible and has good fault tolerant ability.

关键词： fault tolerant control(FTC) signal reconstruction extended state observer(ESO) nonlinear dynamic inversion(NDI)

Polyphase orthogonal sequences design for opportunistic array radar via HGA

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Journal of Systems Engineering and Electronics 2013年第1期24卷 60-67页

作者： Shufeng Gong Weijun Long Hao Huang De Ben Minghai Pan College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing Research Institute of Electronics Technology

Opportunistic array radar （OAR） is a new generation radar system based on the stealth of the platform, which can improve the modern radar performance effectively. Designing the orthogonal code sets with low autocorrelation and cross-correlation is a key issue for OAR. This paper proposes a novel hybrid genetic algorithm （HGA） and designs the polyphase orthogonal code sets with low autocorrelation and cross-correlation properties, which can be used in the OAR system. The novel algorithm combines with simulated annealing （SA） and genetic algorithm （GA）, adds in keeping best individuals and competition in small scope, and introduces grey correlation evaluation to evaluate fitness function. These avoid the premature convergence problem existed in GA and enhance the global searching capability. At last, the genetic results are optimized to obtain the best solution by using greedy algorithm. The simulation results show that the proposed algorithm is effective for the design of orthogonal phase signals used in OAR systems.

关键词： hybrid genetic algorithm (HGA) grey correlation evaluation opportunistic array radar (OAR) orthogonal signal.

Self-polymerization and co-polymerization kinetics of lead methacrylate

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Rare Metals 2021年第3期40卷 736-742页

作者： Yu-Juan Zhang Xin-Tao Guo Chun-Hong Wang De-Feng Wu Ming Zhang School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Department of Materials Research AVIC Manufacturing Technology InstituteBeijing 100024China

Hydrogen nuclear magnetic resonance(H1-NMR) and X-ray diffractometer(XRD) were used to characterize the molecular and crystal structure of lead methacrylate [Pb(MAA)_(2)] which was produced by the double decomposition reaction of lead oxide and methacrylic *** analysis and Kelen-T(u|")dos(K-T) method were used to study the self-polymerization kinetic and the monomer reactivity ratios of Pb(M A A)_(2) and methyl methacrylate(MMA),*** the ternary polymerization method of bulk casting using MMA,Pb(MAA)_(2) and gadolinium methacrylate(Gd(MAA)_(3)) as monomers,we prepared the plexiglass which have neutron and X-ray protection *** results show that the polymerization rate(R_(p)) is expressed as Rp=K[M]^(1.02)[I]^(0.37) below the 10% conversion rate at 70℃,where K is the polymerization rate *** in the N,N-dimethylformamide(DMF) solution,the activation energy required for Pb(MAA)_(2) to initiate self-polymerization by the free radicals is 74.99 kJ·mol^(-1).The reactivity ratios of r1 [Pb(MAA)_(2)] and r2(MMA) are 3.767 *** the thickness of the material increases,the X-ray and thermal neutron shielding ability of the plexiglass containing gadolinium and lead is getting better and better.

关键词： Lead methacrylate Polymerization kinetic Reactivity ratio Plexiglass

Research on variable block size motion estimation algorithm for airborne image

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High Technology Letters 2014年第3期20卷 321-327页

作者：王科 Huang Dongshan Ma Li Zhang Yudong China National Aeronautical Electronic Radio Research Institute School of Electronic Information and Electrical EngineeringShanghai Jiaotong University

A fast motion estimation algorithm for variable block-size using the ＂line scan and block merge procedure＂ is proposed for airborne image compression *** hardware implementation via FPGA is discussed in *** proposed pipelined architecture based on the line scan algorithm is capable of calculating the required 41 motion vectors of various size blocks supported by H.264 within a 16 × 16 block in *** adaptive rate distortion cost function is used for various size block *** motion vectors of adjacent small blocks are merged to predict the motion vectors of larger blocks for reducing *** results show that our proposed method has lower computational complexity than full search algorithm with slight quality decrease and little bit rate *** to the high real-time processing speed it can be easily realized in hardware.

关键词： H.264 motion estimation line scan algorithm rate distortion optimization (RDO) FPGA block merge method

Prediction of Compressive and Shear Moduli of X-cor Sandwich Structures for Aeronautic Engineering

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Transactions of Nanjing University of Aeronautics and Astronautics 2015年第6期32卷 646-653页

作者：张向阳李勇李俊斐范琳谭永刚肖军 College of Material science and Technology Nanjing University of Aeronautics and Astronautics

The so-called″X-cor sandwich structure″is a highly promising novel material as an alternative to honeycomb used in *** much work has been conducted on the performance of the X-cor sandwich structure,the gap is still hardly bridged between experimental results and theoretical ***,a method has been innovated to establish semi-empirical formula for the prediction of compressive and shear moduli of X-cor sandwich structure composites,by combining theoretical analyses and experimental *** addition,aprediction software was first developed based on the proposed method,of which the accuracy was verified through confirmatory *** software can offer a direct reference or guide for engineers in structural designing.

关键词： X-cor sandwich structure moduli prediction compressive shear

Pulsar/CNS integrated navigation based on federated UKF

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Journal of Systems Engineering and Electronics 2010年第4期21卷 675-681页

作者： Jin Liu Jie Ma Jinwen Tian State Key Laboratory for Multi-spectral Information Processing Technologies Institue for Pattern Recognition and artifical Intelligence Huazhong University of Science and Technology Wuhan 430074 P. R. China

In order to improve the autonomous navigation capability of satellite,a pulsar/CNS（celestial navigation system） integrated navigation method based on federated unscented Kalman filter（UKF） is *** celestial navigation is a mature and stable navigation ***,its position determination performance is not satisfied due to the low accuracy of horizon *** pulsar navigation is a new navigation method,which can provide highly accurate range *** major drawback of single pulsar navigation is that the system is completely *** two methods are complementary to each other,the federated UKF is used here for fusing the navigation data from single pulsar navigation and *** to the traditional celestial navigation method and single pulsar navigation,the integrated navigation method can provide better navigation *** simulation results demonstrate the feasibility and effectiveness of the navigation method.

关键词： autonomous navigation celestial navigation system(CNS) pulsar federated unscented Kalman filter(UKF).