JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Computation of Capacitance for MEMS Comb-Drive Structures

LI Ming-hui, GAO Shi-qiao, LIU Hai-peng, LIANG Xin-jian

2009, 18(1): 1-5.

[Abstract](647)

Abstract:
According to the characteristics of comb-drive structures, the electrical potential field is analyzed; the model based on corner capacitor is presented and solved with the capacitance characteristic formula of nonlinear capacitor. Compared with the results of finite element method simulation, the model based on corner capacitor is more accurate than the models based on infinite parallel plate capacitor and parallel plate capacitor with edge effects.

M/OD Risk Assessment System and Its Applications

WANG Hai-fu, YU Qing-bo, LIU You-ying, WANG Hui

2009, 18(1): 6-10.

[Abstract](329)

Abstract:
A risk assessment system named meteoroid & orbital debris risk assessment system (MODRAS) developed for assessing risks of the spacecraft under the meteoroid and debris environment (M/OD EM) is presented. The computing resolution of MODRAS has been verified by both the three generic spacecraft geometries of inter agency debris committee (IADC) and similar foreign software such as BUMPER, ESABASE, and MDPANTO. The results show that the system is fit well with the computing results of the foreign software. Typical applications of the system are also presented, including a manned spacecraft and a space shuttle.

Particles Emission from Gasoline Vehicles

WANG Jun-fang, GE Yun-shan, TAN Jian-wei, HE Chao, YOU Ke-wei, YOU Qiu-wen

2009, 18(1): 11-15.

[Abstract](224)

Abstract:
Number concentration and size distribution from gasoline cars are investigated at transient modes on the chassis dynamometers, which are measured using electrical low pressure impactor (ELPI) for the ECE15 and EUDC cycles. Results indicate that, during cold start, particle number emission is higher than that under hot start. It is found that the number of particles increases with the vehicle speeds. Furthermore, particles with diameter smaller than 200?nm constitute the predominant part of total emission in the entire cycle. In addition, the tentative information about composition of emitted particles is also discussed.

Electromagnetic Compatibility Design for Powertrain Control Module

WANG Yu-ming, CUI Tao, LIU Bo-lan, ZHANG Fu-jun

2009, 18(1): 16-21.

[Abstract](312)

Abstract:
In order to improve the electromagnetic compatibility of powertrain control module (PCM), a system procedure of vehicular PCM electromagnetic alteration is presented in this paper. First of all, the box of the PCM is divided into different cabins to eliminate interferences between power supply circuit, analog circuit and digital circuit. Secondly, the working principle and electromagnetic (EM) characters of all the signals adopted by a typical PCM are analyzed. Then according to specific electromagnetic characters, different measures are adopted in corresponding signal process circuits or signal transfer cables, such as ground layout designing, power supply protecting, signal shielding and drive cable interference suppressing. Finally, further improvement may also needed regarding to practical electromagnetic compatibility test effects. The final test shows that, with all the measures mentioned above, the conducted emission of a PCM can be reduced by 20?dB; meanwhile, the radiated emission can be reduced by 30?dB comparing to the original system.

Design of a Miniature Autonomous Surveillance Robot

ZHENG Chang-e, HUANG Qiang, HUANG Yuan-can

2009, 18(1): 22-26.

[Abstract](306)

Abstract:
The small size of miniature robots poses great challenges for the mechanical and electrical design and the implementation of autonomous capabilities. In this paper, the mechanical and electrical design for a two-wheeled cylindrical miniature autonomous robot ("BMS-1", BIT MicroScout-1) is presented and some autonomous capabilities are implemented by multiple sensors and some arithmetic models. Several experimental results show that BMS-1 is useful for surveillance in confined spaces and suitable for large-scale surveillance due to some autonomous capabilities.

Biomimetic Experimental Research on Hexapod Robot's Locomotion Planning

HUANG Lin, HAN Bao-ling, LUO Qing-sheng, ZHANG Chun-lin, XU Jia

2009, 18(1): 27-31.

[Abstract](231)

Abstract:
To provide hexapod robots with strategies of locomotion planning, observation experiments were operated on a kind of ant with the use of high speed digital photography and computer assistant analysis. Through digitalization of original analog video, locomotion characters of ants were obtained, the biomimetic foundation was laid for polynomial trajectory planning of multi-legged robots, which was deduced with mathematics method. In addition, five rules were concluded, which apply to hexapod robots marching locomotion planning. The first one is the fundamental strategy of multi-legged robots’ leg trajectory planning. The second one helps to enhance the static and dynamic stability of multi-legged robots. The third one can improve the validity and feasibility of legs’ falling points. The last two give criterions of multi-legged robots’ toe trajectory figures and practical recommendatory constraints. These five rules give a good method for marching locomotion planning of multi-legged robots, and can be expended to turning planning and any other special locomotion.

Localized Model and Arithmetic System Based on Two Image Sensors Under Complex Circumstance

HE Guang-lin, YUAN Ben-sheng胜)

2009, 18(1): 32-36.

[Abstract](198)

Abstract:
Two image sensors simulate directly the way of disposing images with the humans two eyes, so it has important value to apply in many domains, such as object identification, small unmaned aerial vehicle (UAV), workpiece localization, robot navigation and so on. The object localization based on two image sensors is studied in this paper. It concentrates on how to apply two charge coupled device (CCD) image sensors to object localization of sphere in complex environments. At first a space model of the two image sensors is set up, then Hough transformation is adopted to get localizated model and arithmetic system. An experiment platform is built in order to prove the correctness and feasibility of that localization algorithm.

Fuzzy Logic Control for Suspension Systems of Tracked Vehicles

YU Yang, WEI Xue-xia, ZHANG Yong-fa

2009, 18(1): 37-40.

[Abstract](360)

Abstract:
A scheme of fuzzy logic control for the suspension system of a tracked vehicle is presented. A mechanical model for the whole body of a tracked vehicle, which is totally a fifteen-degree-of-freedom system, is established. The model includes the vertical motion, the pitch motion as well as the roll motion of the tracked vehicle. In contrast to most previous studies, the coupling effect among the vertical, the pitch and the roll motions of the suspension system of a tracked vehicle is considered simultaneously. The simulation of fuzzy logic control under road surface with random excitation shows that the acceleration,pitch angle and roll angle of suspension system can be efficiently controlled.

Mesh Generation and Dynamic Mesh Management for KIVA-3V

LIU Yong-feng, ZHANG You-tong, XIONG Qing-hui

2009, 18(1): 41-45.

[Abstract](250)

Abstract:
To improve mesh quality for KIVA-3V a method has been developed for rapid mesh generation and dynamic mesh management with moving valves for internal combustion engines. Two phases are included in rapid mesh generation: the initial mesh generation and the mesh pre-treatment. In the second step (pre-treatment), the connectivity of those cells is generated by a new algorithm added to the KIVA-3V code after the initial mesh generated. In dynamic mesh management phase, a new rezoning algorithm is developed and the basic principle is that the rezoning starts from the moving part. The movement of the adjustment is treated as an "earth quake wave" propagating to the surrounding vertexes. The amount of coordinate adjustment of the surrounding vertexes is determined by the movement of the epicenter and the distance between the vertexes and the "epicenter". Finally, a real IC engine mesh is generated and managed according to the new method. It gives a new theory and a new method for creating and managing the mesh in IC engine.

3D Object Recognition Based on Linear Lie Algebra Model

LI Fang-xing, WU Ping-dong, SUN Hua-fei, PENG Lin-yu

2009, 18(1): 46-50.

[Abstract](292)

Abstract:
A surface model called the fibre bundle model and a 3D object model based on linear Lie algebra model are proposed. Then an algorithm of 3D object recognition using the linear Lie algebra models is presented. It is a convenient recognition method for the objects which are symmetric about some axis. By using the presented algorithm, the representation matrices of the fibre or the base curve from only finite points of the linear Lie algebra model can be obtained. At last some recognition results of practicalities are given.

Research on Acoustic Localization Algorithm Based on Dual Four-Element Arrays

WANG Ya-bin, JIA Jing-jing, LIU Ming-jie

2009, 18(1): 51-55.

[Abstract](348)

Abstract:
The passive acoustic locating technology is widely used in military fields. The traditional locating method with single array has low precision of distance estimation, but comparatively high precision of angle estimation. According to the characteristic, the algorithm for acoustic passive localization based on the azimuth angle and geometry position of the two arrays is derived to estimate the target distance, and the simulation for the factors that affect the localization precision also proceeds. The result of the simulation shows the precision of localization estimation with dual arrays is superior to that of single array, and the passive localization algorithm based on dual array can meet the practical demands.

Experimental Study on the Expansion Uniformity of Armature

HE Yuan-hang, WU Bi, MA Yue-fen, ZHANG Qing-ming

2009, 18(1): 56-59.

[Abstract](237)

Abstract:
A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters, which can be applied to study the expansion uniformity of armature in a helical magnetic flux compression generator (HFCG). The influences of wall thickness and initiation position on the expansion uniformity of armature in HFCG were experimentally investigated. The results show that the armature with thinner wall thickness will easily rupture due to the high pressure of detonation products inside, the armature with larger wall thickness will easily crack due to the tensile stress on the outer surface of the wall,the influence of the end effect on the expansion uniformity can be ignored if the distance between the first group of probe and the initiation point is more than 3 times the armature diameter.

Image Retrieval Approach Based on Intuitive Fuzzy Set Combined with Genetic Algorithm

WANG Xiao-yin, XU Wei-hua, HU Chang-zhen

2009, 18(1): 60-64.

[Abstract](384)

Abstract:
Aiming at shortcomings of traditional image retrieval systems, a new image retrieval approach based on color features of image combining intuitive fuzzy theory with genetic algorithm is proposed. Each image is segmented into a constant number of sub-images in vertical direction. Color features are extracted from every sub-image to get chromosome coding. It is considered that fuzzy membership and intuitive fuzzy hesitancy degree of every pixel's color in image are associated to all the color histogram bins. Certain feature, fuzzy feature and intuitive fuzzy feature of colors in an image, are used together to describe the content of image. Efficient combinations of sub-image are selected according to operation of selecting, crossing and variation. Retrieval results are obtained from image matching based on these color feature combinations of sub-images. Tests show that this approach can improve the accuracy of image retrieval in the case of not decreasing the speed of image retrieval. Its mean precision is above 80%.

Novel Channel Estimation Method Based on Decision-Directed in OFDM

BU Xiang-yuan, ZHANG Jian-kang, YANG Jing

2009, 18(1): 65-69.

[Abstract](292)

Abstract:
Based on the analysis of decision-directed (DD) channel estimation by using training symbols, a novel DD channel estimation method is proposed for orthogonal frequency division multiplexing (OFDM) system. The proposed algorithm takes the impact of decision error into account, and calculates the impact to next symbol duration channel state information. Analysis shows that the error propagation can be effectively restrained and the channel variation is tracked well. Simulation results demonstrate that both the signal error rate (SER) and the normalized mean square error (NMSE) performance of the proposed method are better than the traditional DD (DD+LS) and the maximum likelihood estimate (DD+MLE) method.

Improved Multi-channel Blind Image Restoration Algorithm for UWB Radar

WANG Wei-jiang

2009, 18(1): 70-73.

[Abstract](305)

Abstract:
The imaging problem of low signal to noise ratio (SNR) echo is very important for ultra-wide band (UWB) through-wall radar. An improved multi-channel blind image restoration algorithm based on sub-space and constrained least square (CLS) is presented and applied to UWB radar system to deal with this issue. The high resolution of radar image is equivalent to multi-channel blind image restoration based on the improved model of the through-wall radar echo. And a new cost function is proposed to the multi-channel blind image restoration by considering the concept of sub-space as the limitation of blur identification. The proposed algorithm has all advantages of CLS and sub-space, and converts the image estimation to alternating-minimizing the two cost functions. Experimental results prove that the proposed algorithm is effective at improving the resolution of radar image even at low SNR.

Chirp-Rate Resolution of Fractional Fourier Transform in Multi-component LFM Signal

LIU Feng, HUANG Yu, TAO Ran, WANG Yue

2009, 18(1): 74-78.

[Abstract](721)

Abstract:
Distinguishing close chirp-rates of different linear frequency modulation (LFM) signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform (FrFT). Then the expression of chirp-rate resolution in fractional Fourier domain (FrFD) was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can be omitted. What’s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.

Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

YU Li-qiong, HUANG Ru-dan, CHI Ying-nan, XU Yan-qing, HU Chang-wen

2009, 18(1): 79-83.

[Abstract](371)

Abstract:
The title complex, ·3H₂O]_<em>n( 1 ) (Him is imidazole, OH-H₂BDC is 5-hydroxyisophthalic acid), was synthesized by liquid/liquid diffusion method at room temperature. The complex crystallizes in orthorhombic, space groupP2₁2₁2₁, witha0.671?6(7),b1.380?6(2),c1.742?1(2)?nm,V1.615?2(3)?nm³, C₁₁H₁₈CdN₂O₁₀,M_r450.67,D_c1.853?g/cm³,μ1.407?mm^-1,F(000)904,Z4, the finalR₁0.020?9 andwR₂0.045?3 for 3?211 observed reflections (I>2σ(I)). In the structure of 1 , the OH-BDC ligands exhibiting bis-bidentate coordination mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain. It is notable that a series of complicated hydrogen bonds (e.g., N—H…O, O—H…O) exist in the structure, which link neighboring helices into a three-dimensional supramolecular architecture. An observed intense blue luminescence with an emission band peaking at 390?nm for 1 may be resulted from ligand-to-metal charge transfer (LMCT).

Topology Chemical Process Research on the Condensing and Growing Phase Multi Micro Oil Droplets Based on Hydrodynamics

ZHOU Yi, LI Xuan-qi, ZHANG Dong-xiang, TAPACOB B B

2009, 18(1): 84-88.

[Abstract](206)

Abstract:
The hydrodynamic research about the droplet condensing of the multi phase liquid state on the surface of the coal glass and water discusses the deepening process of convex shape curve and the formation of S shape, and puts emphasis on describing the diagram formation method of the later. In the induction period the active diagram of the micro droplet is decided by pH value forming as convex shape diagram or S shape diagram. When pH value is above 4.0, the damage of convex shape diagram cannot be recovered, in that case produce S shape activity diagram. When pH value is equal to or above 12.0, the hard surface with alkali liquid state loses adhesion, so that the micro droplet condensing of the multi phase liquid state stops completely. The research result shows that the water cleaning conditions of getting rid of the oil micro droplets can be decided by the pH value.

Pharmacokinetic Study and Tissue Distribution of Single Mangiferin After Intravenous Administration in Rats

LI Yu-juan, SUI Ying-jie, XIN Nian

2009, 18(1): 89-93.

[Abstract](306)

Abstract:
A simple, sensitive ane selective high performance liquid chromatographic (HPLC) method with UV detection (320?nm) was developed and validated for determination of mangiferin in rat plasma and tissues. Mangiferin and internal standard (spinosin) were separated using mobile phase of acetonitrile-water (20∶80, v/v) with 1% glacial acetic acid and 1% THF on a Phenomenex gemini C₁₈column. The flow rate was 0.7?mL/min. The calibration curves of mangiferin in plasma and tissues were linear over the investigated ranges. The intra- and inter-run precisions for all samples were less than 13.8%. The time-concentration curve of mangiferin after intravenous administration to rats corresponded to two-compartment model. The main pharmacokinetic parametersT_0.5α,T_0.5β, CL and AUC_0-Twere 15.87?min, 26.15?min, 6.1?L/(min·kg) and 3.28?mg·min/mL, respectively. The highest and lowest levels of mangiferin occurred in spleen and brain, respectively. Mangiferin was not found in liver. After intravenous administration, the drug was distributed extensively and transferred quickly in rats in vivo.

Entropy Squeezing in the Quantum Heisenberg XY Spin Chains

CHANG Ping, SHAO Bin, ZOU Jian

2009, 18(1): 94-97.

[Abstract](324)

Abstract:
The time evolution of entropy squeezing for the two-qubit XYZ Heisenberg model in an external uniform magnetic field is investigated in the language of quantum information. The effect of different parameters such as magnetic field and anisotropy parameter on the properties of entropy squeezing and variance squeezing are discussed. It is shown that magnetic field and anisotropy parameter can enhance the entropy squeezing.

Existence of Positive Solutions for Higher-Order Four-Point Boundary Value Problems with ap-Laplacian Operator

LU Yue-feng, GE Wei-gao

2009, 18(1): 98-100.

[Abstract](276)

Abstract:
A class of higher-order four-point boundary value problems with ap-Laplacian operator is studied. By use of a fixed point theorem in cones, sufficient conditions for the existence of positive solutions for the boundary value problems are obtained.

Evolutionarily Cooperative Stable of Science & Technology Alliance Under Self-organized Organization

LIU Li-jun

2009, 18(1): 101-105.

[Abstract](167)

Abstract:
The cooperative evolutionary stability under self-organized organization is discussed in this paper. The differences between the objects studied by cooperative game theory and the ones studied by cooperative game in science & technology alliance are analyzed. The mutant probability of agent’s utility under endogenous technical factor condition is analyzed. By clarifying the connotation of Pareto-dominate institution in cooperative game, the efficient and feasible managerial definition of Pareto-dominate Institution in science & technology alliance is presented. The evolutionarily cooperative game for the agent in Pareto-dominate institution is explained. And then the necessary condition of cooperative evolutionary stabilization based on multi-agent utility's dynamic equilibrium is put forward. Finally, the model of alliance's utility's dynamic equilibrium under self-organization is established.

Profit Allocation Scheme Among Players in Supply-Chain Based on Shapley Value of Fuzzy Bi-cooperative Games

YU Xiao-hui, ZHANG Qiang

2009, 18(1): 106-111.

[Abstract](291)

Abstract:
The Shapley value of fuzzy bi-cooperative game is developed based on the conventional Shapley value of bi-cooperative game. From the viewpoint that the players can participate in the coalitions to a certain extent and there are at least two independent cooperative projects for every player to choose, Shapley value which is introduced by Grabisch is extended to the case of fuzzy bi-cooperative game by Choquet integral. Moveover, the explicit fuzzy Shapley value is given. The explicit fuzzy Shapley function can be used to allocate the profits among players in supply-chain under the competitive and uncertain environment.

Fuzzy-TOPSIS Method with Multi-goal

PANG Jin-hui, ZHANG Qiang

2009, 18(1): 112-116.

[Abstract](331)

Abstract:
To develop the technique for order preference by similarity to an ideal solution, namely, TOPSIS method with multi-goal in fuzzy decision environment. Firstly, a new approach to constructing fuzzy decision matrix by Choquet integral was proposed in multi-goal decision system. Secondly, the concepts of fuzzy positive-ideal solution and fuzzy negative-ideal solution related to the fuzzy decision matrix were given. Finally, the credibility measure was adopted to calculate the distances to fuzzy positive-ideal solution and fuzzy negative-ideal solution. The presented fuzzy-TOPSIS method embodies well both the predetermined preferences and the weights of goals.

Availability Analysis of Parallel Repairable System with Omitted Failures

ZHENG Zhi-hua, CUI Li-rong

2009, 18(1): 117-120.

[Abstract](197)

Abstract:
The new model for parallel repairable system is introduced, and it is based on the practice problems of maintenance and the idea of Ion-Channel modeling. In the new model, repair times that are sufficiently short (less than some critical value) do not result in system failure, and such a repair interval is omitted from the downtime record. Usually, the underlying process is Markov process if the durations of working and repair time have the negative-exponential distributions, but the new system has not the Markov properties, which is worth to study. The reliability indexes such as instantaneous availability and steady-state availabilities for the new system are given through probability analysis. A numerical example is given to illustrate the results.

Research on Technology Early-Warning System Based on Dynamic Information Monitoring

WANG Xue-feng, ZHU Dong-hua, LIU Song, LIU Jia

2009, 18(1): 121-126.

[Abstract](285)

Abstract:
Relying on the advanced information technologies, such as information monitoring, data mining, natural language processing etc., the dynamic technology early-warning system is constructed. The system consists of technology information automatic retrieval, technology information monitoring, technology threat evaluation, and crisis response and management subsystem, which implements uninterrupted dynamic monitoring, trace and crisis early-warning to the specific technology. Empirical study testifies that the system improves the accuracy, timeliness and reliability of technology early-warning.

2009 Vol. 18, No. 1