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Analysis of Porosity and Preheating Temperature on the Decomposition and Combustion Characteristics within 5 N Ammonium Dinitramide(ADN)-based Monopropellant Thruster

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Journal of Thermal Science 2020年第1期29卷 81-89页

作者： ZHANG tao WANG Fengshan CHEN jun Beijing Institute of Control Engineering Beijing 100190China Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology Beijing 100190China

In this study,the effects of porosity of the fore-catalytic bed and after-catalytic bed and preheat temperature on the decomposition and combustion characteristics of a 5N ammonium dinitramide(ADN)-based thruster were numerically investigated in terms of the distribution of components,temperature,and *** results indicated that the porosity of the fore-catalytic bed and preheating temperature significantly affected the decomposition and combustion *** porosity of the fore-catalytic bed was optimized,and the thrust performance was demonstrated to improve with increasing of porosity of the after-catalytic bed and pre-heating *** results were favorable for the investigation of decomposition and combustion characteristics and could also be beneficial to the design and manufacture of different types of ADN-based thrusters.

关键词： porosity preheating temperature decomposition and combustion characteristics ammonium dinitramide monopropellant

Deep Guided Attention Network for Joint Denoising and Demosaicing in Real Image

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Chinese Journal of Electronics 2024年第1期33卷 303-312页

作者： tao ZHANG Ying FU jun ZHANG School of Computer Science and Technology Beijing Institute of Technology Advanced Reasearch Institute of Multidisciplinary Science Beijing Institute of Technology

Denoising(DN) and demosaicing(DM) are the first crucial stages in the image signal processing pipeline. Recently, researches pay more attention to solve DN and DM in a joint manner, which is an extremely undetermined inverse problem. Existing deep learning methods learn the desired prior on synthetic dataset, which limits the generalization of learned network to the real world data. Moreover, existing methods mainly focus on the raw data property of high green information sampling rate for DM, but occasionally exploit the high intensity and signalto-noise(SNR) of green channel. In this work, a deep guided attention network(DGAN) is presented for real image joint DN and DM(JDD), which considers both high SNR and high sampling rate of green information for DN and DM, respectively. To ease the training and fully exploit the data property of green channel, we first train DN and DM sub-networks sequentially and then learn them jointly, which can alleviate the error accumulation. Besides, in order to support the real image JDD, we collect paired raw clean RGB and noisy mosaic images to conduct a realistic dataset. The experimental results on real JDD dataset show the presented approach performs better than the state-of-the-art methods, in terms of both quantitative metrics and qualitative visualization.

关键词： Training Visualization Inverse problems Green products Noise reduction Pipelines Signal processing

Elastic Behavior of Polymer Chains

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Chinese Journal of Chemical Physics 2008年第5期21卷 463-468页

作者： Teng Lu tao Chen Hao-jun Liang Hefei National Laboratory for Physical Sciences at Microscale Department of Polymer Science andEngineering University of Science and Technology of China Hefei 230025 China

The elastic behavior of the polymer chain was investigated in a three-dimensional off-lattice model. We sample more than 109 conformations of each kind of polymer chain by using a Monte Carlo algorithm, then analyze them with the non-Gaussian theory of rubberlike elasticity, and end with a statistical study. Through observing the effect of the chain flexibility and the stretching ratio on the mean-square end-to-end distance, the average energy, the average Helmholtz free energy, the elastic force, the contribution of energy to the elastic force, and the entropy contribution to elastic force of the polymer chain, we find that a rigid polymer chain is much easier to stretch than a flexible polymer chain. Also, a rigid polymer chain will become difficult to stretch only at a quite high stretching ratio because of the effect of the entropy contribution. These results of our simulation calculation may explain some of the macroscopic phenomena of polymer and biomacromolecular elasticity.

关键词： Monte Carlo algorithm Three-dimensional off-lattice model Elastic behavior Polymer

Simulation of 3D Flow in Turbine Blade Rows including the Effects of Coolant Ejection

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Journal of Thermal Science 2008年第2期17卷 111-115页

作者： Jian-jun LIU bai-tao AN Yun-tao ZENG Institute of Engineering Thermophysics Chinese Academy of SciencesP. O. Box 2706 Beijing 100080 CHINA

This paper describes the numerical simulation of three-dimensional viscous flows in fir-cooled turbine blade rows with the effects of coolant ejection. A TVD Navier-Stokes flow solver incorporated with baldwin-Lomax turbulence model and multi-grid convergence acceleration algorithm are used for the simulation. The influences of coolant ejection on the main flow are accounted by volumetric coolant source terms. Numerical results for a four-stage turbine are presented and discussed.

关键词： Numerical Simulation Air-Cooled Turbine Blade Row Coolant Ejection

Demand response management of smart grid based on Stackelberg-evolutionary joint game

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Science China(Information Sciences) 2023年第8期66卷 169-186页

作者： jun LI tao LI Daoyi DONG School of Mathematics-Physics and Finance Anhui Polytechnic University Key Laboratory of Pure Mathematics and Mathematical Practice School of Mathematical SciencesEast China Normal University School of Engineering and Information Technology University of New South Wales

We investigated the real-time pricing demand response management system of multiple microgrids and multiple power users. Accordingly, we have proposed a Stackelberg-evolutionary joint game framework to examine the real-time pricing scheme of multiple microgrids and multiple power users so as to establish equilibrium strategies. Both a non-cooperative game among multiple microgrids and a multipopulation evolutionary game among multiple power users were considered. Furthermore, we constructed a Stackelberg game between microgrids and power users to reflect their sequential interaction, wherein the microgrids are leaders, and the power users are followers. We also proved the existence and uniqueness of the Stackelberg equilibrium. Furthermore, we proposed an iterative algorithm to compute the equilibrium strategy and demonstrate the convergence and effectiveness through numerical simulations, which demonstrated that the algorithm could achieve a balance between power supply and demand balance.

关键词： smart grid real-time pricing demand response management Stackelberg game multi-population evolutionary game

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Redundant discrete wavelet transforms based moving object recognition and tracking

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Journal of Systems Engineering and Electronics 2009年第5期20卷 1115-1123页

作者： Gao tao Liu Zhengguang Zhang jun School of Electrical Engineering and Automation Tianjin Univ. Tianjin 300072 P. R. China

A method for moving object recognition and tracking in the intelligent traffic monitoring system is presented. For the shortcomings and deficiencies of the frame-subtraction method, a redundant discrete wavelet transform （RDWT） based moving object recognition algorithm is put forward, which directly detects moving objects in the redundant discrete wavelet transform domain. An improved adaptive mean-shift algorithm is used to track the moving object in the follow up frames. Experimental results show that the algorithm can effectively extract the moving object, even though the object is similar to the background, and the results are better than the traditional frame-subtraction method. The object tracking is accurate without the impact of changes in the size of the object. Therefore the algorithm has a certain practical value and prospect.

关键词： traffic monitoring moving object recognition moving object tracking redundant discrete wavelet.

Camera,LiDAR,and IMU based Multi-Sensor Fusion SLAM:A Survey

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Tsinghua Science and Technology 2024年第2期29卷 415-429页

作者： jun Zhu Hongyi Li tao Zhang Department of Automation Tsinghua UniversityBeijing 100084China

In recent years,Simultaneous Localization And Mapping(SLAM)technology has prevailed in a wide range of applications,such as autonomous driving,intelligent robots,Augmented Reality(AR),and Virtual Reality(VR).Multi-sensor fusion using the most popular three types of sensors(e.g.,visual sensor,LiDAR sensor,and IMU)is becoming ubiquitous in SLAM,in part because of the complementary sensing capabilities and the inevitable shortages(e.g.,low precision and long-term drift)of the stand-alone sensor in challenging *** this article,we survey thoroughly the research efforts taken in this field and strive to provide a concise but complete review of the related ***,a brief introduction of the state estimator formation in SLAM is ***,the state-of-the-art algorithms of different multi-sensor fusion algorithms are *** we analyze the deficiencies associated with the reviewed approaches and formulate some future research *** paper can be considered as a brief guide to newcomers and a comprehensive reference for experienced researchers and engineers to explore new interesting orientations.

关键词： multi-sensor fusion Simultaneous Localization And Mapping(SLAM) navigation localization

GLRT Detectors for Aircraft Wake Vortices in Clear Air

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Chinese Journal of Aeronautics 2010年第6期23卷 698-706页

作者： Li jun Wang Xuesong Wang tao School of Electronic Science and Engineering National University of Defense TechnologyChangsha 410073China

In this article, radar echoes of aircraft wake vortices are modeled as weighted sums of the frequency components of the echoes with a special covariance matrix for the weighted coefficients. With a proposed detection scheme, two generalized likelihood ratio test (GLRT) detectors are derived respectively for aircraft wake vortices with time-varying and time-invariant Doppler spectra. Then the analytical expressions for detection and false alarm probabilities of the detectors are derived and three factors are investigated which mainly influence the detection performance, i.e., the Doppler extension and uncertainty of the aircraft wake vortex, and the number of the detection cells. The results indicate that, the signal-to-noise ratio (SNR) loss induced by Doppler extension is generally several decibels. The SNR loss due to Doppler uncertainty is approximately proportional to the logarithm of the number of spectrum lines in the uncertain Doppler spectrum intervals. For a large number of detection cells, the SNR gain is approximately proportional to the square root of the number of the detection cells.

关键词： radar detector generalized likelihood ratio test aircraft wakes vortex flow

UMR: A utility-maximizing routing algorithm for delay-sensitive service in LEO satellite networks

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Chinese Journal of Aeronautics 2015年第2期28卷 499-507页

作者： Lu Yong Zhang jun Zhang tao School of Electronics and Information Engineering Beihang University

This paper develops a routing algorithm for delay-sensitive packet transmission in a low earth orbit multi-hop satellite network consists of micro-satellites. The micro-satellite low earth orbit （MS-LEO） network endures unstable link connection and frequent link congestion due to the uneven user distribution and the link capacity variations. The proposed routing algorithm, referred to as the utility maximizing routing （UMR） algorithm, improve the network utility of the MS-LEO network for carrying flows with strict end-to-end delay bound requirement. In UMR, first, a link state parameter is defined to capture the link reliability on continuing to keep the end-to-end delay into constraint; then, on the basis of this parameter, a routing metric is for- mulated and a routing scheme is designed for balancing the reliability in delay bound guarantee among paths and building a path maximizing the network utility expectation. While the UMR algo- rithm has many advantages, it may result in a higher blocking rate of new calls. This phenomenon is discussed and a weight factor is introduced into UMR to provide a flexible performance option for network operator. A set of simulations are conducted to verify the good performance of UMR, in terms of balancing the traffic distribution on inter-satellite links, reducing the flow interruption rate, and improving the network utility.

关键词： Delay bound LEO satellite networks Micro-satellite Network utility QoS routing