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A new concept and preliminary study of variable hypersonic inlet with fixed geometry based on shockwave control

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Science China(Technological Sciences) 2007年第5期50卷 644-657页

作者： TAN HuiJun CHEN Zhi li guangsheng College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The inlet plays a significant role in the hypersonic airbreathing propulsion. A fixed-geometry inlet is troubled by low air-capture ratio and large additional drag while operating below the design Mach number. Whereas a variable-geometry inlet can maximize performance, but adds weight and complexity to the propulsion system. Based on a fluidic shock shape control technique, this paper proposes a new concept of variable hypersonic inlet with fixed geometry, gives the realization scheme, and conducts a preliminary validation. The results show that the control of the external shock system and the effective throat area can be achieved by the self-provided high pressure fluid of the inlet. For an inlet with an operating Mach-number region of 4 to 6, the shock-on-lip condition can be maintained from Mach 5 to Mach 6 with the maximum expense of 1.8% secondary flow ratio, result- ing in 20% extra captured mass flow and 8% less forebody drag at low Mach num- bers compared with conventional fixed-geometry inlets. Thus, the performance enhancement by using the proposed variable inlet can substantially benefit the acceleration process of hypersonic vehicles at low Mach numbers.

关键词： hypersonic inlets, variable inlets, shock shape control technique

Multi-robot coordinated exploration of indoor environments using semantic information

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Science China(Information Sciences) 2018年第7期61卷 247-257页

作者： guangsheng li Wusheng CHOU Fang YIN School of Mechanical Engineering and Automation Beihang University State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang University

Dear editor,Multi-robot exploration of indoor environments is a fundamental problem in mobile robotics[1].In the context of multi-robot exploration,the main challenge is in achieving coordination among the robots such that they can be better distributed over the environment for simultaneously exploring different regions and avoiding interference with other robots[2,3].To date,many approaches

关键词： In Multi-robot coordinated exploration of indoor environments using semantic information DBSCAN Figure HMM

Influence of heating rate on reactivity and surface chemistry of chars derived from pyrolysis of two Chinese low rank coals

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International Journal of Mining Science and Technology 2018年第4期28卷 610-616页

作者： liang Dingcheng Xie Qiang li guangsheng Cao Junya Zhang Jun School of Chemical and Environmental Engineering China University of Mining and Technology (Beijing)

A series of char samples were derived from pyrolysis of two typical low-rank coals in China （Shengli lig- nite and Shenmu bituminous coal） at low, medium and fast heating rates, respectively, to the same pyrol- ysis temperature 750℃. Then these chars were characterized by means of thermogravimetric analysis and Fourier transform infrared spectrometer with the aim to investigate the influence of heating rate in pyrolysis process on gasification reactivity and surface chemistry of them. Besides, a homogeneous model was used to quantitatively analyze the activation energy of gasification reaction. The results reveal that Shengli lignite and its derived chars behave higher gasification reactivity and have less content of oxygen functional groups than Shenmu coal and chars. Meanwhile, chars derived from Shengli lignite at 50℃/min and Shenmu coal at 200℃/min have the greatest gasification reactivity, respectively. The oxygen functional groups in Shengli lignite are easily thermo-decomposed, and they are less affected by the heating rate, while that in Shenmu coal have a significant change with the variation of heating rate. In addition, there is no good correlation between the change of oxygen functional groups and that of the gasification reactivity of the derived chars from pyrolysis at different heating rates.

关键词： Pyrolysis Low rank coal Heating rateReactivity Kinetic parameter Surface chemistry

The trapping effect of sulfur sensitization center Ag_2S cluster on T-grain AgBrI microcrystals

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Science China(Physics,Mechanics & Astronomy) 2004年第6期47卷 744-751页

作者： YANG Shaopeng FU guangsheng li Xiaowei TIAN Xiaodong College of Physics Science and Technology Hebei University Baoding 071002 China College of Physics Science and Technology Hebei University Baoding 071002 China College of Physics Science and Technology Hebei University Baoding 071002 China College of Physics Science and Technology Hebei University Baoding 071002 China

The microwave absorption dielectric-spectrum technique was used to study the decay kinetics of photoelectrons in sulfur-sensitized silver halide crystals. The time-resolution spectrum of free electrons and shallow-trapped electrons generated in sulfur-sensitized AgBrl crystals has been obtained. The relationship of the trapping effect of sensitization centers Ag2S and sensitization time or temperature in emulsions has been duscussed. With the increase in the sensitization time and temperature, the trap effect of sulfur sensitization centers varies from hole trap to shallow electron trap, and deep electron trap.

关键词： silver halide, sulfur-sensitized, photoelectron, trapping effect, microwave absorption dielectric-spectrum.

Semantic categorization of indoor places using CNN for mobile robot exploration

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High Technology Letters 2018年第2期24卷 125-133页

作者： li guangsheng Chou Wusheng School of Mechanical Engineering and Automation Beihang University Beijing 100191 P. R. China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 P. R. China

The ability of achieving a semantic understanding of workspaces is an important capability for mobile robot. A method is proposed to categorize different places in a typical indoor environment by using a Kinect sensors for mobile robot exploration. At first, the invariant feature based images stitching approach is adopted to form a panoramic image according to Kinect visual information, and the translation between Kinect depth information and obstacle distance information is performed to obtain virtual liDAR data. Then, the semantic classifier is designed by using convolutional neural networks （CNN） for indoor place eategorization based on Kinect visual observations with panoramic view. At last, a frontier-based exploration method is applied to carry out indoor autonomous exploration of mo- bile robots, which integrates the CNN-based categorization approach. The proposed method has been implemented and tested on a real robot, and experiment results demonstrate the approach effective- ness on solving the semantic categorization problem for mobile robot exploration.

关键词： exploration mobile robot semantic categorization convolutional neural network(CNN) Kinect

Preparation of κ-carra-Oligosaccharides with Microwave Assisted Acid Hydrolysis Method

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Journal of Ocean University of China 2015年第2期14卷 345-349页

作者： li guangsheng ZHAO Xia LV Youjing li Miaomiao YU Guangli Key Laboratory of Marine Drugs Ministry of Education Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology School of Medicine and PharmacyOcean University of China

A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of oligosaccharides was detected by high performance thin layer chromatography （HPTLC） and polyacrylamide gel electrophoresis （PAGE）. Considering the results of HPTLC and PAGE, the optimum condition of microwave assisted acid hydrolysis was determined. The concentration of κ-carrageenan was 5 mgmL-1; the reaction solution was adjusted to pH 3 with diluted hydrochloric acid; the solution was hydrolyzed under microwave irradiation at 100 ℃ for 15 min. Oligosaccharides were separated by a Superdex 30 column （2.6 cm × 90 em） using AKTA Purifier UPC100 and detected with an online refractive index detector. Each fraction was characterized by electrospray ioni- zation mass spectrometry （ESI-MS）. The data showed that odd-numbered κ-carra-oligosaccharides with DP ranging from 3 to 21 could be obtained with this method, and the structures of the oligosaccharides were consistent with those obtained by traditional mild acid hydrolysis. The new method was more convenient, efficient and environment-friendly than traditional mild acid hydrolysis. Our results provided a useful reference for the preparation of oligosaceharides from other polysaccharides.

关键词： κ-carrageenan oligosaccharides microwave degradation acid hydrolysis

Magnetic rotation in Rubidium-84

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Nuclear Science and Techniques 2013年第3期24卷 61-65页

作者： SHEN Shuifa HAN Guangbing WEN Shuxian YAN Yupeng WU Xiaoguang ZHU lihua HE Chuangye li guangsheng Institute of Nuclear Energy Safety Technology Chinese Academy of Sciences School of Physics Suranaree University of Technology Thailand Center of Excellence in Physics (ThEP) Commission on Higher Education State Key Laboratory of Nuclear Physics and Technology (Peking University) School of Physics Shandong University China Institute of Atomic Energy P. O. Box 275(10) School of Physics and Nuclear Energy Engineering Beihang University

High-spin states in 84 Rb have been studied by using the 70Zn(18O, p3n)84Rb reaction at beam energy of 75MeV. Three regular magnetic dipole bands including strong M1 and weak E2 transitions have been observed in this nucleus which shows the characteristic feature of magnetic rotation. These bands are interpreted in the projected shell model for the first time on the basis of the four-quasiparticle configuration of the type π(fp)π(g29/2)v(g9/2). It is shown that the calculated sequence lies roughly in the same energy range as the experimental one but the interval between neighboring levels is larger than the corresponding experimental value. We believe that a 4-quasiparticle band crossing with the 2-quasiparticle band will depress the energies of the states.

关键词：磁旋转电子束能量投影壳模型高自旋态磁偶极子 E2跃迁能量范围时间间隔

An improved potential field method for mobile robot navigation

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High Technology Letters 2016年第1期22卷 16-23页

作者：李广胜 Chou Wusheng Robotics Institute Beijing University of Aeronautics and Astronautics

In order to overcome the inherent oscillation problem of potential field methods(PFMs) for autonomous mobile robots in the presence of obstacles and in narrow passages,an enhanced potential field method that integrates Levenberg-Marquardt(L-M) algorithm and k-trajectory algorithm into the basic PFMs is proposed and *** first,the mobile robot navigation function based on the basic PFMs is established by choosing Gaussian ***,the oscillation problem of the navigation function is investigated when a mobile robot nears obstacles and passes through a long and narrow passage,which can cause large computation cost and system *** last,the L-M algorithm is adopted to modify the search direction of the navigation function for alleviating the oscillation,while the k-trajectory algorithm is applied to further smooth *** a series of comparative experiments,the use of the L-M algorithm and k-trajectory algorithm can greatly improve the system performance with the advantages of reducing task completion time and achieving smooth trajectories.

关键词： potential field oscillation Gaussian model Levenberg-Marquardt (L-M)algorithm k-trajectory

Dramatic transition between electric and magnetic rotations in ^(106)Ag

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1669-1675页

作者： ZHENG Yun ZHU liHua CHEN YongShou WU XiaoGuang HE ChuangYe HAO Xin liU Ying WANG ZhiMin li XueQin li guangsheng GAO ZaoChun SUN HuiBin China Institute of Atomic Energy School of Physics and Nuclear Energy Engineering Beihang University Faculty of Science Shenzhen University School of Environmental and Biological Engineering Nanjing University of Science and Technology Nuclear and Radiation Safety Center Ministry of Environmental Protection

The lifetimes for the states of magnetic dipole band in106Ag have been measured using the Doppler-shift attenuation method via the reaction of100Mo(11B,5n)106Ag at a beam energy of 60 *** reduced transition strengths of the magnetic dipole band,the B(M1)/B(E2)ratios together with the signature of the level energy as a function of angular momentum for the positive parity states of106Ag show that a drastic change of excitation mode,that is,from electric rotation to magnetic rotation,occurs within one unit of spin at around Iπ=12+.Theoretical calculations based on the triaxial projected shell model consistently reproduce the experimental data and provide an explanation on the nature of observed phenomena such that the dynamical drift of the rotational axis suddenly from the principal axis to the tilted one,along the positive parity bands of106Ag.

关键词： lifetime measurements DSAM TPSM magnetic rotation electric rotation