JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

On Chaotification of Discrete Hamilton Systems

LI Guang-cheng, XIE Jia-fang, YUE Bao-zeng

2007, 16(1): 1-4.

[Abstract](129)

Abstract:
The chaotification problem of discrete Hamilton systems in one dimensional space is investigated and corresponding chaotification theorem is established. Feedback control techniques is used to make arbitrary discrete Hamilton systems chaotic, or enhance its existing chaotic behaviors. By designing a universal controller and combining anti-integrable limit it is proved that chaos of the controlled systems is in the sense of Devaney. In particular, the systems corresponding to the original systems and designed controllers are only required to satisfy some mild assumptions. Moreover, the range of the coefficient of the controller is given.

Constraint Stabilization and One Step Correction Method for Dynamical Systems

SHANG Mei, CHEN Xiang-wei, MEI Feng-xiang

2007, 16(1): 5-8.

[Abstract](141)

Abstract:
A computational method of constraint stabilization and correction is introduced. The method is based on the Baumgart's one-step method. Constraint conditions are addressed to stabilize and correct the solution. Two examples are given to illustrate the results of the method.

Electrorheological Damper and Its Application for Semi Active Suspension System

ZHAO Xia, ZHANG Yong-fa

2007, 16(1): 9-12.

[Abstract](213)

Abstract:
A semi-active control of vehicle suspension system with electrorheological (ER) damper is presented. ER fluid characteristics are introduced based on the Bingham plasticity model first. Then ER damper working force is given. Finally a quarter car model with ER damper is constructed. The skyhook control strategy is adopted to simulate the amplitude-frequency characteristics and the vibration of suspension system under random road excitation on the basis of ER damper characteristics. The response curves of the vertical acceleration, the suspension dynamic working space and the tyre dynamic loading are obtained. Simulation results show that the acceleration is reduced effectively and then the ride comfort is improved by the skyhook control law.

Dynamical Mechanical Properties for AD90 Alumina

REN Hui-lan, NING Jian-guo, LI Ping

2007, 16(1): 13-17.

[Abstract](76)

Abstract:
The dynamic response of polycrystalline alumina was investigated in the pressure range of 0-13 GPa by planar impact experiments. Velocity interferometer system for any reflector(VISAR) was used to obtain free surface velocity profile and determine the Hugoniot elastic limit, and manganin gauges were employed to obtain the stress-time histories and determine Hugoniot curve. Both the free surface particle velocity profiles and Hugoniot curves indicate the dispersion of the "plastic" wave for alumina. With the measured stress histories, the complete histories of strain, particle velocity, specific volume and specific internal energy are gained by using path line principle of Lagrange analysis. The dynamic mechanical behaviors for alumina under impact loading are analyzed, such as nonlinear characteristic, strain rate dependence, dispersion and declination of shock wave in the material.

Dynamic Scheduling of Flexible Job Shops

SHAHID Ikramullah Butt, SUN Hou-fang

2007, 16(1): 18-22.

[Abstract](180)

Abstract:
Aim of this research is to minimize makespan in the flexible job shop environment by the use of genetic algorithms and scheduling rules. Software is developed using genetic algorithms and scheduling rules based on certain constraints such as non-preemption of jobs, recirculation, set up times, non-breakdown of machines etc. Purpose of the software is to develop a schedule for flexible job shop environment, which is a special case of job shop scheduling problem. Scheduling algorithm used in the software is verified and tested by using MT10 as benchmark problem, presented in the flexible job shop environment at the end. LEKIN software results are also compared with results of the developed software by the use of MT10 benchmark problem to show that the latter is a practical software and can be used successfully at BIT Training Workshop.

Study on the Availability Opening Size of Throttle and Affection to the Velocity Characteristic of Shock Absorber

ZHOU Chang-cheng, ZHENG Zhi-yun, GU Liang, CHEN Yi-jie

2007, 16(1): 23-27.

[Abstract](205)

Abstract:
Based on the solution of the governing differential equation for deformation of throttle slice while satisfying required boundary conditions, the coefficient (Gr) and an analytical formula for computing the deformation of throttle slice is presented through equivalency transformation, which is a concise, accurate and practical method for throttle slice design and characteristic analysis. Researched the deformation at any radius, compared with ANSYS FEA software by the simulation analysis, the availability opening size of throttle that was defined by the deformation at the valve mouth radius is studied. The affection of valve mouth radius to the damper characteristic is analyzed. Tests are made for the damper characteristic, compared with simulation results, it is shown that Gr method is an accurate computation method for computing the deformation of throttle slice at valve mouth radius, suitible to use in the damper design, analysis, and verification. The deformation at mouth radius could not be replaced with the outside radius.

Longitudinal Control Strategy f or Vehicle Adaptive Cruise Control Systems

WU Li-jun, LIU Zhao-du, MA Yue-feng

2007, 16(1): 28-33.

[Abstract](201)

Abstract:
A new longitudinal control strategy for vehicle adaptive cruise control (ACC) systems is presented. The running relationship between the ACC vehicle and the detected target vehicle is described by the relative velocity and the deviation between the actual headway distance and the prescribed safety distance. Based on this, two state space models are built and the linear quadratic optimal control theory is used to yield desired velocity for the ACC-equipped vehicle when with the target vehicle detected. By switching among four control modes, the desired velocity profile is designed to deal with different running situations. A velocity controller, which includes a PID controller for throttle openness and a neural network controller for brake application, is developed to achieve the desired velocity profile. The proposed control strategy is applied to a non-linear vehicle model in a simulation environment and is shown to provide the ACC vehicle comfortable ride and satisfying safety.

Electronic Brake Force Distribution Control Methods of ABS Equipped Vehicles During Cornering Braking

WANG Guo-ye, LIU Zhao-du, MA Yue-feng, QI Zhi-quan

2007, 16(1): 34-37.

[Abstract](299)

Abstract:
Based on the dynamics of ABS-equipped vehicles during cornering braking, the electronic brake-force distribution (EBD) control methods of ABS-equipped vehicles during cornering braking are proposed. According to the dynamics and the tire model under tire adhesion limit, the stability acceptance criteria of vehicles during cornering braking are proposed. According to the stability acceptance criteria and the ABS control, the EBD control methods of ABS-equipped vehicles during cornering braking are implemented by adjusting the threshold values of tires slip independently. The vehicle states during cornering braking at two typical initial velocities of the vehicle are analyzed by the EBD control methods, whose results indicate the EBD control methods can improve the braking performances of the vehicle during cornering braking comparing with the ABS control.

Key Human Factors of Vehicle Interior Occupant Packaging in SAE Standard

DING Yi, HU Ping, JIN Chun-ning, WU Xiao-jun

2007, 16(1): 38-44.

[Abstract](139)

Abstract:
Fourteen SAE standards related to accommodation and occupant packaging for vehicle interior are studied. The influencing factors, key reference accommodation points and major design dimensions and their relationships of occupant packaging and ergonomics during the vehicle interior layout design and development are analyzed. Prototypes are presented to verify the results and how to achieve the packaging is shown. Automobile designers can achieve significant practical guidance for human safety, efficiency accommodation and occupant packaging of all passengers during the vehicle design process.

Experimental Analysis of Dynamic Stiffness Coefficient of the New Mn Cu Alloy Annular Parts

WANG Cheng-lin, ZHANG Zhi-jing, YE Xin, JIN Xin, WEN Li-wei, LEI Zhu-fang, WANG Yong-chao

2007, 16(1): 45-49.

[Abstract](92)

Abstract:
Based on excitation-resonance mass testing principle, a proper experiment testing system is designed for annular parts. The dynamics characters of the axis sleeve, which is made of a new Mn-Cu alloy and used as a vibration reductor in high acceleration rotary testing machine for fusee, is investigated. The relationship between stiffness coefficient and utilizing frequency is obtained, and the simplified dynamics model of crystal is established. From the viewpoint of crystal microstructure of the Mn-Cu alloy, the experiment result is analyzed by the viscoelastic theory, and the characters of stress and strain in the condition of high frequency are discussed. The results indicate that the Mn-Cu alloy annular parts are fit to be used on the high accleration rotary testing machine for fusee.

Design and Simulation of BTT Missile with High-Aspect-Ratio Wing Robust H∞Autopilot

CUI Sheng-wang, LIU Li, MA Chun-yan

2007, 16(1): 50-55.

[Abstract](174)

Abstract:
For the strong coupling among the channels of bank-to-turn (BTT) missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop design, the question of pole-zero cancellation is solved, and the stabilization of structured uncertainty is achieved. Through the outer loop of H∞ controller design, the flying performance and robustness can be guaranteed. The nonlinear simulation results show that the autopilot designed has perfect time domain response, and can suppress bad influence of the inertial and kinematics couplings. It can make the missile fly stably in the large flying areas. The control is very effective.

Voxel Based Morphometric Study on Chinese Blind Mens Brain Structure

YANG Chun-lan, PAN Wen-ju, ZHENG Lian

2007, 16(1): 56-60.

[Abstract](182)

Abstract:
Many studies have shown the functional relevance of cross-modal plasticity in blind men. In order to study the changes of their brain structure, voxel-based morphometry (VBM) methods are used. The regional gray matter (GM) and white matter (WM) concentrations of magnetic resonance (MR) images from 11 blind people and 9 sighted control subjects are compared using standard VBM. Optimized VBM is also discussed to measure the absolute local volume of GM or WM. Consistent results are achieved by statistical analysis with these methods. There are distinct differences not only in visual cortex but also the sensory area, auditory area and motor area. GM concentrations in blind men significantly decreased in Brodmann 7 and 22. While in Brodmann 18 and 19, GM concentration increased. GM volumes decreased in Brodmann 3,4,6,9 and 45. On the other hand, both WM concentration and volume increased in Brodmann 7. These results suggest that early visual deprivation can lead to changes in the brain structural anatomy which is consistent with the cortical cross-modal reorganization found by functional imaging. It may help to discover the relationship between the brain structural anatomy and the brain functional data of blind men at a macroscopic level from neuroimaging perspective.

Hand Motion Tracking Using Simulated Annealing Method in a Discrete Space

LIANG Wei, JIA Yun-de, LIU Tang-li, HAN Lei, WU Xin-xiao

2007, 16(1): 61-66.

[Abstract](246)

Abstract:
Hand tracking is a challenging problem due to the complexity of searching in a 20+ degrees of freedom (DOF) space for an optimal estimation of hand configuration. The feasible hand configurations are represented as a discrete space, which avoids learning to find parameters as general configuration space representations do. Then, an extended simulated annealing method with particle filtering to search for optimal hand configuration in the proposed discrete space, in which simplex search running in multi-processor is designed to predict the hand motion instead of initializing the simulated annealing randomly, and particle filtering is employed to represent the state of the tracker at each layer for searching in high dimensional configuration space. Experimental results show that the proposed method makes the hand tracking more efficient and robust.

Immunity Based Worm Detection System

HONG Zheng, WU Li-fa, WANG Yuan-yuan

2007, 16(1): 67-73.

[Abstract](81)

Abstract:
Current worm detection methods are unable to detect multi-vector polymorphic worms effectively. Based on negative selection mechanism of the immune system, a local network worm detection system that detects worms was proposed. Normal network service requests were represented by self-strings, and the detection system used self-strings to monitor the network for anomaly. According to the properties of worm propagation, a control center correlated the anomalies detected in the form of binary trees to ensure the accuracy of worm detection. Experiments show the system to be effective in detecting the traditional as well as multi-vector polymorphic worms.

Application of Adaptive Reduced Sigma Points Unscented Kalman Filter to the Tracking of Maneuvering Target

ZHOU Zhan-xin, CHEN Jia-bin

2007, 16(1): 74-77.

[Abstract](196)

Abstract:
Based on the principle of statistical linear regression, a set of n+2 sigma points instead of 2n+1 sigma points used in the unscented Kalman filter (UKF), is constructed to approximate the system state. And filter accuracy is second order. Real-time of modified UKF is improved. In order to describe accurately the maneuvering target, the "current" statistical model is used. And the equation of acceleration error covariance is modified at every sample time of the filter. The modified adaptive UKF is presented for estimating the position, velocity and acceleration of maneuvering target. Monte Carlo simulations show the modified adaptive UKF acquires good performance for tracking position of maneuvering target. The modified adaptive UKF has better computational efficiency than UKF.

Use of Virtual Medium in Designing of the CGH Wave Front Generator for Aspheric Testing

KANG Guo-guo, XIE Jing-hui, LIU Yi

2007, 16(1): 78-82.

[Abstract](201)

Abstract:
Design method and procedures of computer-generated hologram (CGH) used for aspheric test are introduced in detail. For CGH phase calculation, virtual medium which has zero refractive index at given wavelength is used to model ideal aspheric wavefront. Reflective Fresnel zones located in a ring area concentric to the CGH structure is designed to reduce or eliminate alignment errors. Substrate figure error, pattern distortion, etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained to guide the tolerance distribution during CGH fabricating. A design example is given and the uncertainty of measurement achieves λ/20.

Design of Fuze Antenna Beamformer Based on DSP

FENG Qing-juan, HUANG Zhong-hua, LI Ping

2007, 16(1): 83-86.

[Abstract](92)

Abstract:
According to the algorithm of the fuze antenna beamforming and the requirement for the realtime performence, a fuze antenna beamformer based on digital signal processor (DSP) was designed. The program was written in C, and in order to reduce the operation time of DSP, the key part of the matrix operation was written in simple algorithm. The precise and speediness of DSP calculation results were analyzed through Matlab and the Profiling tools in Code Composer Studio (CCS). The results show that the precise and the speediness both can satisfy the requirement for the fuze antenna beamforming.

Design and Realization of Phased Array Radar Optical Fiber Transmission System

HU Shan-qing, LIU Feng, LONG Teng

2007, 16(1): 87-92.

[Abstract](179)

Abstract:
One optical fiber transmission system is designed. The modularization optical fiber transmission adapters were utilized in the system, so the system structure could be flexibly scalable. The sub-array adapter and signal processor adapter were designed and realized utilizing the new field programmable gate array (FPGA) which could drive the optical transceiver. The transmission agreement was designed based on the data stream. In order to solve the signal synchronization problem of the optical fiber transmitted phased array radar, a method named synchronous clock was designed. The fiber transmission error code rate of the system was zero with an experimental transmission velocity of 800 Mbit/s. The phased array radar system has detected the airplane target, thus validated the feasibility of the design method.

Finite Element Analysis of the 2 m Telescope Assemble

ZHAO Fu, WANG Ping, ZHAO Yue-jin, ZHANG Li, XIN Hong-bing

2007, 16(1): 93-97.

[Abstract](296)

Abstract:
To improve the performance of the 2 m telescope, the optimum design is applied to the telescope assemble. Referring to the telescope assemble with the dimetric truss, a group of reasonable sizes of the telescope assemble are found by optimization methods and modal analysis, which will raise the resonant frequency by 4.21%. As a result, the telescope assemble is less likely to resonate. Besides, the dynamic response module in ANSYS is utilized to analyze the modal type, harmonic vibration response and random vibration response of the telescope assemble. By the calculation of ANSYS, finite element analysis (FEA) method proves that the performance of the telescope assemble is mildly enhanced by means of optimum design.

Absorption Capability Comparison of Two Kinds of Super Absorbent Resins from Carboxymethyl Cellulose

LI Jie, DING Cai-xia, LUAN Chang, QU Peng-fei, MA Li-fang

2007, 16(1): 98-102.

[Abstract](98)

Abstract:
The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in aqueous solution. The structures of the two resins were characterized with Fourier transform infrared spectroscopy FTIR, scanning electron miscroscopy (SEM), and environment scanning electron miscroscopy (ESEM), the results indicate that the fibriform of the carboxymethyl cellulose (CMC) is disappeared and the crosslink networks in copolymer of carboxymethyl cellulose-graft-polyacrylic acid(CMC-g-PAA) are denser than that of copolymer of carboxymethyl cellulose-graft-poly(acrylic acid-co-N-vinyl Pyrrolidone)(CMC-g-PAA-co-PVP). The comparison between the two resins in absorption capacities is that CMC-g-PAA is better in the water-keep capability being heated, while CMC-g-PAA-co-PVP is better in the water absorbency and salt resistance.

Flash Pyrolysis Study of MnTC and NiCT by UsingT Jump/FTIR Spectroscopy

SUN Yuan-hua, ZHANG Tong-lai, ZHANG Jian-guo, QIAO Xiao-jing, YANG Li

2007, 16(1): 103-107.

[Abstract](85)

Abstract:
Flash pyrolysis of MnTC([Mn2(TNR)2(CHZ)2(H2O)4]·2H2O) and NiCT([Ni(CHZ)3](TNR)·5H2O) is conducted by using T-jump/FTIR spectroscopy under 0.1 MPa Ar atmosphere. The mole fractions of the individual products in the pyrolysis gas mixture are described as a function of time. Results show that NiCT appears to produce more N2O, NH3 and HONO upon flash pyrolysis, thus secondary oxidation reduction reactions may take place to a certain extent during its thermal decomposition, which in turn leads to unsteady combustion and possibly to failure of the device. While H2O and CO2 are the major two gas products of flash pyrolysis of MnTC, it warrants further in-depth trials for the adoption in detonators as eco-friendly and chemically compatible primary explosive. The two compounds both liberate volatile metal carbonate, oxide and isocyanate compounds.

Preparation and Characterization of Cyclodextrin Derivatized Ovalbumin Used as Chiral Selector in Pressure Capillary Electrochromatography

YU Yu-hong, TANG Li, DAI Rong-ji, DENG Yu-lin, FU Ruo-nong

2007, 16(1): 108-111.

[Abstract](103)

Abstract:
Synthesis and properties of β-cyclodextrin derivatized ovalbumin used as chiral selector were investigated. β-cyclodextrin derivatized ovalbumin was synthesized using β-cyclodextrin and ovalbumin in the presence of ethylene glycol diglycidyl ether in boric acid buffer at pH value 8.7 at 37 ℃. Amino group was coated on the internal surface of the silica capillary by sol-gel technology with triethoxylmethylsiloxane and (3-aminopropyl)trimethoxysiloxane. Covalent binding of β-cyclodextrin derivatized ovalbumin was performed by glutaraldehyde. Enantiomers of chlorpheniramine, phenylalanine and atropine were separated by pressure capillary electrochromatography column coated with β-cyclodextrin derivatized ovalbumin.

Stress Field of Straight Edge Dislocation in Magnetic Field

LIU Zhao-long, HU Hai-yun, FAN Tian-you

2007, 16(1): 112-115.

[Abstract](209)

Abstract:
To study the changes in mechanical properties of materials within magnetic fields and the motion of dislocations, stress fields of dislocation in magnetic field need to be calculated. The straight edge dislocation is of basic importance in various defects .The stress field of straight edge dislocation in an external static magnetic field is determined by the theory of elasticity and electrodynamics according to the Volterra dislocation model for continuous media. This reduces to the known stress field when the magnet field is zero. The results can be used for further study on the strain energy of dislocations and the interactions between dislocations in magnetic fields.

On the Variational Problems of the Functionals with Derivatives of Higher Orders and Undetermined Boundary

LAO Da-zhong, TAN Tian-min

2007, 16(1): 116-121.

[Abstract](77)

Abstract:
According to the necessary condition of the functional taking the extremum, that is its first variation is equal to zero, the variational problems of the functionals for the undetermined boundary in the calculus of variations are researched, the functionals depend on single argument, arbitrary unknown functions and their derivatives of higher orders. A new view point is posed and demonstrated, i.e. when the first variation of the functional is equal to zero, all the variational terms are not independent to each other, and at least one of them is equal to zero. Some theorems and corollaries of the variational problems of the functionals are obtained.

Profit Allocation Scheme among Partners in Virtual Enterprises Based on Fuzzy Shapley Values

CHEN Wen, ZHANG Qiang, WANG Ming-zhe

2007, 16(1): 122-126.

[Abstract](112)

Abstract:
Fuzzy Shapley values are developed based on classical Shapley values and used to allocate profit among partners in virtual enterprises (VE). Axioms of the classical Shapley value are extended to Shapley values with fuzzy payoffs by using fuzzy sets theory. Fuzzy Shapley function is defined based on these extended axioms. From the viewpoint the allocation for each partner should be a crisp value rather a fuzzy membership function at the end of cooperation, a crisp allocation scheme based on fuzzy Shapley values is proposed.

2007 Vol. 16, No. 1