JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Regression-Based Method of Acoustic Detection

1996, 5(2): 95-100.

[Abstract](243) [PDF 332KB](27)

Abstract:
Based on the signal detection theory. a target detection method with the regression calculation which is easily achieved by computer software or hardware was developed in order to insure the acoustic detection system working with high detection possibility and under the condition of low signal to noise ratio. Meanwhile. the physical implication of detection formula wsa discussed and computer result was shown.

The Fourier Transform of a Sort of Generalized Function

Zhu Tongjiang

1996, 5(2): 101-106.

[Abstract](247) [PDF 139KB](29)

Abstract:
The Fourier transforms of functions X ln e are given. where λ is a complex constant (λ≠-1,-2. …), a is a complex number. m=0. 1. 2,…,and

Velocity of a Liquid Drop with a Sorption-Controlled Surfactant

Chen Jinnan

1996, 5(2): 107-116.

[Abstract](279) [PDF 521KB](27)

Abstract:
The terminal velocity of a liquid droplet settling in a sulfactant solution has been studied for the non-linear adsorption Langmuir frameworks accounting for monolayer saturation and non-ideal surfactant interactions. Most prior research uses a linear adsorption model which cannot capture these effects, The Maragoni migration of a liquid drop settling through a surfactant solution is examined by using Langmuir framework. The solution concentration Ceq is assumed large enough for the surfactant mass transfer to be adsorption-controlled. Langmuir model generates non-linear Marangoni stresses which diverge in the limit of approaching ∝, strongly retarding U'.

Dynamic Theory of Electric Breakdown for Oxides

Zou Jian, Ding Hongzhi, Xing Xiusan

1996, 5(2): 117-121.

[Abstract](278) [PDF 380KB](30)

Abstract:
The dynamic aspects of dielectric breakdown (DB) is studied in this article. A quantitative model based on impact ionization is presented. The formulae of microdefect growth rate and lifetime prediction are derived and show fair agreement with experimental data in SiO2. All the fitting parameters have definite physical meanings.

Capillary Electrochromatography Using C₈Open Tubular Column Prepared by Sol-Gel Technique

Li Fang, Jin Hui, Gu Junling, Fu Ruonong

1996, 5(2): 122-122.

[Abstract](316) [PDF 62KB](24)

Abstract:
Open tubthar C8 columns were prepared by sol-gel technology and used in the electrochromatographic separations.

Synthesis and Characterization of Nonlinear Optical Material of Substituted Diacetylenes with Azophenyl Group and Pyrimidine Ring

Wang Jianghong, Yu Congxuan, Shen Yuquan

1996, 5(2): 123-129.

[Abstract](351) [PDF 399KB](28)

Abstract:
?-(2-methylthio -4 -methyl -5 -pyrimidinyl)-2. 4 - pentadiyn- 1 -ol- (4- N. N-dimethylamino-azobenzene -4' -sulfonate) (PDABS - 1 ). ②5 -(2 -methylthio -4 -methyl -5-pyrimidinyl)- 2.4 -pentadiyn- 1 -ol - (azobenzene - 4 -sulfonate) (PDABS -2 ). ③2. 4 -hexadiyn - 1 -ol-6- (4 - N, N-dimethylamino-azobenzene-4'-sulfonate) (HDABS - 1 ), ④2. 4 -hexadiyn - 1-ol -6 - (azobenzene4-sulfonate) (HDABS-2), the four new compounds are synthesize. The structures of the new compounds have been demonstrdted by elemental analysis. IR(KBr). 1H-NMR (CD3CO/TMS),MS. Their X(3), d33. βμ and the fabrication of their polarization orientated thin film also have ben reported in this paper.

Synthesis and Characterization of Several Degradable Aliphatic Polyanhydrides

Shuai Xintao, Tan Huimin

1996, 5(2): 130-136.

[Abstract](272) [PDF 406KB](26)

Abstract:
The following copolymers based on aliphatic sebacic acid were synthesized through a vacuum-melt polycondensation process:poly(sebacic acid)-b-poly(isophthalic acid)(PSA-PIPH).poly (sebacic acid) -b- (tartaric acid) (PSA-PTTA). poly (sebacic acid) -b-poly (ethylene glycol)(PSA-PEG). copolymers of PSA and copolyether (M1= 1500) of epoxy ethane and (tetrahydrofuran)(PSA-PEG/THF). All these copolymers were characterized by means of 1H or 13C NMR. IR spectrometry. differential scanning calorimetry (DSC). Intrinsic viscosity and melting points were measured to estimate the molecular weights of polymers. DSC measurements indicated that PSA-PEG. PSA-PEG/THF have much lower crystallinity. On the other hand,PSA-PIPH and PSA-PTTA exhibit better film or fibre-forming properties than PSA.

Entropy Increase and Nature of Separation

Liang Heng, Wang Zhenggang, Fu Ruonong, Lin Bingcheng

1996, 5(2): 137-143.

[Abstract](278) [PDF 365KB](26)

Abstract:
The entropy increase (EI) and the entropy increase per unit time (EIPUT) of the solute zone are chosen as new criteria of separation efficiency in chromatography and electrophoresis. It is verified by grand canonical ensemble (GCE) that the kinetic energy distribution of the solute is a common characteristic of the entropy and the distribution of solute zones.Under the assumptions. EI of the solute system is directly proportional to the logarithm of the difference between one and one half of the substantial separation ratio. the ratio of moles of a sparated solute to its total moles. and EIPUT is direchy proportional to corrected separation rate of separation system. EI or EIPUT is a important bridge between separation efficiency of chromatography or electrophoresis and operating parameters, especially. when nonequilibriumthermodynamics(NET) would be adopted.

Influence of Bioelectret Materials on cell Culture

Kou Tongxin, Sun Shan, Deng Baiming, Sun Caomin, Zhu Hesun

1996, 5(2): 144-147.

[Abstract](295) [PDF 231KB](29)

Abstract:
The aim of this work is to study the effects of the electret property of natural biopolymers (such as collagen) on tissue repair. Type I collagen was prepared from pigskin,and polarized by using the TSDC (thermally stimulated depolarization current) technique. The polarized materials are used for cell culture. and then the cell growth curve is drawn. It was found that the polarized biomaterials accelerated cell differentiation. which indicates that they may be applied in the biomedical field.

The Techniques to Reduce Variations within One Plate

Liang Qihong, Zhang Disheng, Geng Qingbo, Chen Jindi

1996, 5(2): 148-154.

[Abstract](289) [PDF 407KB](25)

Abstract:
Conventional techniques to control variations within one plate have been based on preset models and constant automatic position control (APC or pressure feedback automatic gauge control(PAGC).However.because of the rolling force prediction error in the preset models and of the inadequate response speed of dynamic system and of the eccentricity, etc.,the conventional method has not given satisfactory results, the statistics'variations within one plate are in range of 0.25-0.60 mm The authors have developed the techniques to control the variations, which are dynamic intelligent control of hydraulic screwdown system. synchronism control of hydraulic screwdown, eccentricity control method by rotary encoder and the curve of modulus of mill measured automatically, etc., The techniques were fully and successfully industrialized in The Plate Mill of Maanshan Iron and Steel Company and good results that variations are in range of 0.08-0.15min hare been obtained in that mill.

A Novel Method of Testing Aspherical Surface

Xin Qiming, Gao Hong, Gao Yun

1996, 5(2): 155-161.

[Abstract](262) [PDF 354KB](27)

Abstract:
A set-up based on a special shadow method, pinhole method, was made and some experiments were done. The results show that this novel method is simple, easy to operate,and suitable for testing large aspherical surfaces quantitatively.

The Reliability Design of a Kind of Multioption Fuze

Deng Jiahao, Shi Jusheng

1996, 5(2): 162-170.

[Abstract](336) [PDF 544KB](30)

Abstract:
On the basis of analysing the reliability problems existing in the general design of a kind of multioption fuze. some problems such as the reliability model. the reliability distribution of the electronic part of the fuze are discussed. For a particular multioption fuze, then.according to three different setting ways. the calculating methods of its operating reliability in six different operating states are given.

Fractal Studies on Dielectric Ageing

Ding Hongzhi, Zhao Rubao, Xing Xiusan, Zhu Hesun

1996, 5(2): 171-176.

[Abstract](320) [PDF 172KB](30)

Abstract:
A stochastic model of conducting crack propagation is presented to provide a conceptual framework dedicated to the study of the formation of fractal structure of dielectric ageing patterns as a result of a competition between random fluctuation growth and applied electric strength enhanced deterministic growth. The necessary and sufficient conditions resulting in fractal behaviour in dielectric ageing are found.

An Adaptive Block-Based Fractal Image Coding Scheme

Deng Yuanmu, Ke Youan

1996, 5(2): 177-183.

[Abstract](274) [PDF 480KB](26)

Abstract:
Based on Jacquin's work. this paper presents an adaptive block-based fractal image coding scheme. Firstly. masking functions are used to classify range blocks and weight the mean Square error (MSE) of images. Secondly, an adaptive block partition scheme is introduced by developing the quadtree partition method. Thirdly. a piecewise uniform quantization strategy is appled to quantize the luminance shifting. Finally. experiment results are shown and compared with what reported by Jacquin and Lu to verify the validity of the methods addressed by the authors.

Generalization Capabilities of Feedforward Neural Networks for Pattern Recognition

Huang Deshuang

1996, 5(2): 184-192.

[Abstract](269) [PDF 513KB](27)

Abstract:
This paper studies the generalization capability of feedforward neural networks (FNN).The mechanism of FNNs for classification is investigated from the geometric and probabilistic viewpoints. It is pointed out that the outputs of the output layer in the FNNs for classification correspond to the estimates of posteriori probability of the input pattern samples with desired outputs 1 or 0. The theorem for the generalized kernel function in the radial basis function networks (RBFN) is given. For an 2-layer perceptron network (2-LPN). an idea of using extended samples to improve generalization capability is proposed. Finally. the experimental results of radar target classification are given to verify the generaliztion capability of the RBFNs.

Mathematical Models of Tire-Longitudinal Road Adhesion and Their Use in the Study of Road Vehicle Dynamics

Liu Zhaodu

1996, 5(2): 193-204.

[Abstract](337) [PDF 581KB](42)

Abstract:
Mathematical models of tire-longitudinal road adhesion for use in the study of road vehicle dynamics are set up so as to express the relations of longitudinal adhesion coefficients with the slip ratio. They perfect the Pacejka's models in practical use by taking into account the influences of all essential parameters such as road surface condition. vehicle velocity. slip angle. vertical load and slip ratio on the longitudinal adhesion coefficients. The new models are more comprehensive more concise. simpler and more convenient in application in all kinds of simulations of car dynamics in various sorts of braking modes.

A New Three-Level Hierarchical Control Algorithm for Large-Scale Systems

Xie Sanming, Wu Cangpu, Xu Zhongling

1996, 5(2): 205-211.

[Abstract](259) [PDF 413KB](29)

Abstract:
This paper presents a new three-level hierarchical control parallel algorithm for large-scale systems by spatial and time decomposition. The parallel variable metric (PVM)method is found to be promising third-level algorithm. In the subproblems of second-level, the constraints of the smaller subproblem requires that the initial state of a subproblem equals the terminal state of the preceding subproblem. The coordinating variables are updated using the modified Newton method. the low-level smaller subproblems are solved in parallel using extended differential dynamic programmeing (DDP). Numerical result shows that comparing with one level DDP. the PVM /DDP algorithm obtains significant speed-ups.

1996 Vol. 5, No. 2