JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Initial Value Problem of Singular n-Laplacian Equation

2001, 10(3): 225-232.

[Abstract](151)

Abstract:
To show some theorems on the existence of singular initial value problem with n Laplacian operator, topology method and methods of analysis are employed. Some existence theorems for initial value problems with n Laplacian operators are established in three singular cases.

Large Deviation Theorem for Empirical Measures of Degenerate Diffusion Processes

LIU Xiu qin, XI Fu bao

2001, 10(3): 233-239.

[Abstract](251)

Abstract:
A class of multi dimensional degenerate diffusion processes X ε(t) in R r(r≥2) are considered and the asymptotic properties of empirical measures are investigated; here X ε(t) saitisfies the stochastic differential equation dX ε(t)=σ(X ε(t)) d W(t)+B(X ε(t)) d t+ εσ～(X ε(t)) d W(t),ε>0. X ε(t) are small random perturbations of the degenerate diffusion process X(t), which satisfies the stochastic differential equation dX(t)=σ(X(t)) d W(t)+B(X(t)) d t. A large deviation theorem for projection measures ν on R r-n (n

Nonequilibrium Statistical Modeling of Fatigue Crack Growth Behaviour

HU Hai yun, XING Xiu san

2001, 10(3): 240-245.

[Abstract](170)

Abstract:
In order to study the influence of microstructural texture on the growth of short fatigue cracks in metals, the nonequilibrium statistical theory of fatigue fracture correlating a microscopic mechanism with the macroscopic properties is modified to take into consideration the microstructural features of a material, thereby allowing a rationalisation of the experimental data of short fatigue crack growth and long fatigue crack growth. The nonequilibrium statistical theory thus developed relates the growth of cracks with a dislocation mechanism to simulate short fatigue crack growth with the long fatigue crack growth behaviour and predicts the fatigue crack growth rates throughout the fatigue lifetime. The results is finally compared with that of other fatigue theories.

Exact Wave Function of a Quantum Oscillator with Time-Dependent Frequency and Driving

PENG Yan ze, PENG Song qing, FAN Tian you

2001, 10(3): 246-249.

[Abstract](176)

Abstract:
The harmonic oscillator with time? dependent frequency and driving is studied by means of a new, simple method. By means of simple transformations of variables, the time dependent Schrdinger equation is first transformed into the time independent one. And then exact wave function is found in terms of solutions of the classical equation of motion of the oscillator.

Anti-Plane Elasticity Problem and Mode Ⅲ Crack Problem of Cubic Quasicrystal

ZHOU Wang min, FAN Tian you, YIN Shu yuan, WANG Nian peng

2001, 10(3): 250-254.

[Abstract](107)

Abstract:
The fracture theory of cubic quasicrystal was developed. The exact analytic solution of a Mode Ⅲ Griffith crack in the material was obtained by using the Fourier transform and dual integral equations theory, and so the displacement and stress fields, the stress intensity factor and strain energy release rate were determined. The results show that the stress intensity factor is independent of material constants, and the strain energy release rate is dependent on all material constants. These provide important information for studying the deformation and fracture of the new solid material.

Modeling and Identification of Anisotropic Damping Property of Ni-Based Alloys by FEM-Simulation

HAN Jian bao

2001, 10(3): 255-259.

[Abstract](144)

Abstract:
The modeling and identification of anisotropic damping property of Ni based single crystal alloys are presented. The anisotropic material damping property is modeled by 3 D rheological equations and identified by using specimen modal damping ratios and FEM simulation. The measured damping ratios which exhibit strong anisotropy are predicted better by the method presented than by other methods.

Application of the Sub-Model Method in the Engine Strength Analysis

ZOU Wen sheng, ZUO Zheng xing, FENG Hui hua, LIAO Ri dong

2001, 10(3): 260-265.

[Abstract](86)

Abstract:
On the basis of introducing the fundamental theory and the basic analysis steps of the sub model method, the strength of the new engine complex assembly structure was analyzed according to the properties of the engine structures, some of the key parts of the engine were analyzed with refined mesh by sub model method and the error of the FEM solution was estimated by the extrapolation method. The example showed that the sub model can not only analyze the comlex structures without the restriction of the software and hardware of the computers, but get the more precise analysis result also. This method is more suitable for the strength analysis of the complex assembly structure.

Stability of Oil Film and Output Speed of Hydroviscous Drive Affected by the Pressure of Control Oil

HUANG Xiao guang, WEI Chen guan

2001, 10(3): 266-271.

[Abstract](166)

Abstract:
Based on the theories of hydraulics and nonlinear control system, the model of hydroviscous drive (HVD) was established, the influences of small ripple of control oil pressure on the output speed of HVD and the stability of oil film between friction disks were analyzed. The conclusion presents that when the frequency of the control oil's pressure ripple is higher than 60?Hz and the peak is less than 0 05?MPa, HVD can work stably. The result is useful for studying the application of frequency conversion technology in regulation of control oil pressure.

Theoretical Study on the Temporary Cavity Caused by a High Speed Projectile When Wounding Living Organisms

AN Bo, JIANG Hao zheng, LI Yang

2001, 10(3): 272-277.

[Abstract](175) [PDF 192KB](6)

Abstract:
Analyzes and calculates the process of development of a temporary cavity in the muscle directly after a projectile wounds organisms at a high speed. The muscle is taken as a non compressible Voigt Kelvin viscoelastic fluid model, on the assumption of moving in a radial direction and on spherical symmetry, a theoretical model proposed using the basic equations of the non Newtonian fluid mechanics. The model can well describe the pulsation process of the temporary cavity and changes of pressure in the cavity. The calculated results are in correspondence with the experimental results. The model can be applied in the quantitative analysis of a temporary cavity.

HC Emission Analysis of Gasoline Direct Injection Engines and Challenge Faced by Such Engines in Meeting Future's Emission Standard

HUANG Ying, GE Yun shan, ZHANG Fu jun, ZHAO Jing wei

2001, 10(3): 278-284.

[Abstract](138) [PDF 175KB](7)

Abstract:
Based on the introduction of the basic combustion concept of gasoline direct injection(GDI) engine and its operation under different operating conditions, HC emission mechanisms of the GDI engine are analyzed. And HC emission characteristics of the GDI engine are compared with the PFI engine via a comparison test based on the FTP 75 driving cycle. It can be concluded that the GDI engine is facing a big challenge in meeting the future's HC emission standard. Reasons for the higher HC emissions of the GDI engine are discussed and the ways for HC emission control are given.

Sensor Registration in Asynchronous Data Fusion

HU Shi qiang, ZHANG Tian qiao

2001, 10(3): 285-290.

[Abstract](193)

Abstract:
To find an effective method to estimate and remove the registration error in asynchronous multisensor system, Kalman filtering technique and least squares approach have been proposed to estimate and remove sensor bias and sensor frame tilt errors in multisensor systems with asynchronous data. Simulation results is presented to demonstrate the performance of these approaches. The least squares approach can compress measurements to any time. The Kalman filter algorithm can detect registration errors and use the information to converge tracks from independent sensors. This is particularly important if the data from the sensors are to be fused.

Distributed Computation Models for Data Fusion System Simulation

ZHANG Yan, ZENG Tao, LONG Teng, CUI Zhi she

2001, 10(3): 291-297.

[Abstract](188)

Abstract:
An attempt has been made to develop a distributed software infrastructure model for onboard data fusion system simulation, which is also applied to netted radar systems, onboard distributed detection systems and advanced C3I systems. Two architectures are provided and verified: one is based on pure TCP/IP protocol and C/S model, and implemented with Winsock, the other is based on CORBA (common object request broker architecture). The performance of data fusion simulation system, i.e. reliability, flexibility and scalability, is improved and enhanced by two models. The study of them makes valuable explore on incorporating the distributed computation concepts into radar system simulation techniques.

New Structural Self-Organizing Fuzzy CMAC with Basis Functions

HE Chao, XU Li xin, DONG Ning, ZHANG Yu he

2001, 10(3): 298-305.

[Abstract](220)

Abstract:
To improve the nonlinear approximating ability of cerebellar model articulation controller(CMAC), by introducing the Gauss basis functions and the similarity measure based addressing scheme, a new kind of fuzzy CMAC with Gauss basis functions(GFCMAC) was presented. Moreover, based upon the improvement of the self organizing feature map algorithm of Kohonen, the structural self organizing algorithm for GFCMAC(SOGFCMAC) was proposed. Simulation results show that adopting the Gauss basis functions and fuzzy techniques can remarkably improve the nonlinear approximating capacity of CMAC. Compared with the traditional CMAC,CMAC with general basis functions and fuzzy CMAC(FCMAC), SOGFCMAC has the obvious advantages in the aspects of the convergent speed, approximating accuracy and structural self organizing.

Integrated Assembly Structure Design Within Concurrent Engineering

CHANG Xiang qing, NING Ru xin, YAO Jun, ZHANG Xu, TANG Cheng tong

2001, 10(3): 306-311.

[Abstract](257)

Abstract:
Taking a microwave product as an example, a system of integrated assembly structure design is presented. Getting design constraints from the upstream design section through product data management(PDM), the system generates the assembly scheme using the case? based method, then assigns the design requirements into each component of the assembly. The detail design for each component can be performed under these design constraints. In order to practise concurrent design, the system sends the final design result to the upstream section and downstream section through PDM to achieve information sharing and integration.

Influence of the Dosage of Surfactant on the Electrorheological Behaviors of Fluids

ZHANG Shao hua, ZHANG Yu ling

2001, 10(3): 312-315.

[Abstract](120)

Abstract:
To investigate the influence of surface characteristics of particles on electrorheological (ER) fluids, water free complex strontium titanate particles were synthesized through the sol gel technique and different mass fraction of the surfactant was doped in particles and dispersed in silicon oil. The test shows that surface characteristics of particles have great influence on the behavior of ER fluids. Surface tension, surface polarity and interfacial polarization are strongly related to the surface status of the dispersed particles.

Programming Technology of IP Multicast and Broadcast Based on Socket

LI Dong xia, SU Guang chuan

2001, 10(3): 316-321.

[Abstract](193)

Abstract:
Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.

Synthesis of Two Furazano Azides

LI Zhan xiong, OU Yu xiang, CHEN Bo ren

2001, 10(3): 322-325.

[Abstract](107) [PDF 101KB](2)

Abstract:
bis(azidomethyl) 3,3′ bis(1,2,4 oxadiazole)(Ⅰ) and bis(azidoacetamino) oxazofurazan(Ⅱ) were synthesized. The structures of these two compounds have been identified by IR, 1H NMR, MS and elemental analysis. Azido groups were introduced into furazan derivatives and energetic materials of high nitrogen content and high enthalpy of formation can be obtained. The densities of compound Ⅰ and Ⅱ are relatively high. Compound Ⅰ is an azide of lower melting point, it is hopeful to be applied as energetic plastic additives.

Integrated ABS/ASR/ACC System for the Car

LIU Zhao du, LU Jiang, SHI Kai bin, AN Wei

2001, 10(3): 326-330.

[Abstract](289)

Abstract:
The individual functions of ACC and ABS/ASR are described in the improvements of active safety while the road vehicles travel at a high speed. Being a logic extension of and many inherent connections with ABS/BSR, ACC is easily integrated with ABS/ASR to form an integrated system by adding the headway distance? detecting device to the existing ABS/ASR system and expanding the ABS/ASR software. The algorithm flowcharts and control methods of the ABS/ASR/ACC are given. The advantages of the ABS/ASR/ACC system compared with those using the stand alone systems ABS, ASR and ACC are mentioned in details.

Driving Behavior Shaping Model in Road Traffic System

WANG Wu hong

2001, 10(3): 331-336.

[Abstract](213)

Abstract:
In order to give a new way for modeling driving behavior, identifying road traffic accident causation and solving a variety of road traffic safety problems such as driving errors prevention and driving behavior analysis, a new driving behavior shaping model is proposed, which could be used to assess the degree of effect of driving error upon road traffic safety. Driver behavior shaping model based on driving reliability and safety analysis could be used to identify the road traffic accident causation, to supply data for driver's behavior training, to evaluate driving procedures, to human factor design of road traffic system.

2001 Vol. 10, No. 3