JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Efficient Algorithm for Unconstrained Optimization Problems ——A Positive Definite Update from Negative Broyden Family

Bi Jinbo

1997, 6(4): 299-304.

[Abstract](207)

Abstract:
Abstract A computational implementation of Broyden family of variable metric methods was presented, in which the parameter θ had distinct valurs at various iterations and θ was made less than zero as far as possible Numerical resultsof solving some test problems by the algorithms with a few schemes for selecting θand the BFGS method were given for comparison to demonstrate that the algorithmis efficient for unconstrained optimization problems

A Hybrid Method for Electromagnetic Coupling in Large Spaces

Wang Jiaying, Gao Benqing

1997, 6(4): 305-312.

[Abstract](192)

Abstract:
A hybrid method combining finite difference time domain(FDTD)with topology network was presented to treat with electromagnetic couplings and transmissions in large spaces A generalized matrix euqation expressing the relations among wave vectors at every port of the network nodes was give Scattering characteristics and electromagnetic distributions of every node was calculated independently using FDTD A structure of irises in a waveguide was taken as numerical examples This hybrid method has more advantages than the traditional FDTD method which includes saving calculation time,saving memory spaces and being flexible in setting up FDTD grids

An Approach to the Flame Retardancy of EVA Copolymer by Plasma Treatmentc2

Shi Laishun, Wang Jianqi

1997, 6(4): 313-320.

[Abstract](163)

Abstract:
An attempt was made in the paper aiming at imparting flame retardancy to polymers by plasma grafting technique Based on EVA copolymers with different VA contents the author tried to use the Ar plasma followed by grafting with/without subsequent saponification and metal ion exchange expediting the charring of polymers upon heationg Characterization of the flammability of the plasma treated EVA copolymers grafted with acrylic monomers(MAA,AA and AAm)indicates that this approach turns out to be a promising way and worthy doing whatever in research and/or applications

Application of Multicapillary Column to High Speed GC Separation of Industrial Chemicals

Zhang Hanbang, Fu Ruonong, Wen Yuxiu

1997, 6(4): 321-326.

[Abstract](216) [PDF 194KB](3)

Abstract:
Two multicapillary coluumns(SE 30 and Carbowax 20M)were used for high speed GC separation of positional isomers of industrial chemicals The performances of the two multicapillary columns were also evaluated,such as the effects of carrier velocity,column temperature and sample capacity Two typical explosive isomers(DNT and TNT)were well separated on SE 30 multicapillary column,while some important chemicals(e g xylenes,xylenols)were separated on Carbowax 20M multicapillary column at high speed The multimulticapillary column shows the feature of fast analysis,relatively lower column temperature and larger sample capacity

Single Polar Compound Bioelectret Material and Its Influence on the Cell Growth

Shi Xiangyang, Deng Baiming, Sun Caomin

1997, 6(4): 327-335.

[Abstract](254) [PDF 277KB](2)

Abstract:
To explore the influence of compound bioelectret material′s dielectric property on the cell growth,several kinds of compound bioelectret materials of collagen/chitosan were developed Their TSDC(thermally stimulated depolarization current)spectra were analyzed,and the compound bioelectret collagen/chitosan whose t α and I α were 37℃ and 2×10 -9 A respectively at polarized state was selected The cell culture study showed that the compound bioelectret material could promote normal cell growth when singly negatively polarized,and could inhibit cancer cell growth when singly positively polarized It proves that the rational designation of compound bioelectret has a broad application for clinical medicine

Antitumor Activity of the Ganoderma Lucidum Spore Alcohol Extract in Vitro

Yang Xinlin, Zhu Hesun, Xu Jianlan, Kuang Qun

1997, 6(4): 336-340.

[Abstract](208)

Abstract:
Several cancer cell lines(epithelioma cells or leukemia cells)from human being or mouse were first used to study the antitumor activity of the Ganoderma lucidum spore alcohol extract(GLSAE)in vitro by the MTT test A comparision was made between the sporodermbroken(SB)and sporoderm nonbroken(SN)GLSAE It was showed that both GLSAE SB and GLSAE SN could inhibit the proliferation of these cancer cells,but the activity of GLSAE SB was much higher than that of GLSAE SN These results suggested that Ganoderma lucidum spore could probably be used for tumor treatment

ANN Model and Learning Algorithm in Fault Diagnosis for FMS

Shi Tianyun, Wang Xinyi, Zhang Zhijing, Zhu Xiaoyan

1997, 6(4): 341-349.

[Abstract](157)

Abstract:
The fault diagnosis model for FMS based on multi layer feedforward neural networks was discussed An improved BP algorithm,the tactic of initial value selection based on genetic algorithm and the method of network structure optimization were presented for training this model ANN(artificial neural network)fault diagnosis model for the robot in FMS was made by the new algorithm The result is superior to the rtaditional algorithm

And Gate Recognition System for Short Range Targets

Wang Junbo, Zhou Zhonglai, Shi Jusheng

1997, 6(4): 351-356.

[Abstract](170)

Abstract:
Being aimed at the weakness of short range target′s threshold value recognition system,the double passage And Gate recognition system was put forward on the correlativity of target signals and randomness of noise signals Through state analysis and inference of state transition probability,both the reliability and early burst probability of the system were obtained in theory

Analysis and Design of Broadband Stacked Microstrip Patch Antennas

Xu Xiaowen, Xu jian, Liu Zhangfa, Zhu Bocheng, Li Shizhi

1997, 6(4): 357-362.

[Abstract](221)

Abstract:
A broadband microstrip patch antenna was analyzed and designed.Full wave analysis method(FWAM) was employed to show that a stacked microstrip dual patch antenna(SMDPA) might have a much wider bandwidth than that of the ordinanry uni patch one.By means of discrete complex image theory(DCIT),the Sommerfeld integrals (SI) involved were accurately calculated at a speed several hundred times faster than numerical integration method(NIM).The feeding structure of the SMDPA was then improved and the bandwidth was extended to about 22% or more for voltage standing wave ratio (VSWR)s≤2 Finally,a matching network was constructed to obtain a bandwidth of about 25% for s≤1.5.

An Algorithm for Partitioning Polygons into Convex Parts

Zhou Peide

1997, 6(4): 363-368.

[Abstract](900) [PDF 125KB](11)

Abstract:
An algorithm for partitioning arbitrary simple polygons into a number of convex parts was presented. The concave vertices were determined first, and then they were moved by using the method connecting the concave vertices with the vertices of falling into its region B,so that the primary polygon could be partitioned into two subpolygons. Finally, this method was applied recursively to the subpolygons until all the concave vertices were removed. This algorithm partitions the polygon into O(l) convex parts, its time complexity is max(O(n),O(l 2)) multiplications, where n is the number of vertices of the polygon and l is the number of the concave vertices.

Characterization on Surface and Interfacial Properties of Nitramine Crystal Fillers and Polymeric Bonding Agents

Wu Wenhui, Zheng Bin, Yao Weishang

1997, 6(4): 369-375.

[Abstract](214) [PDF 212KB](5)

Abstract:
The surface and interfacial properties of polymeric bonding agents and nitramine crystal fillers were studied. The surface free energy and adhesion work of polymeric bonding agents and nitramine fillers were calculated by using Kaeble′s equations. It was observed that the hydroxyl values of neutral polymeric bonding agents (NPBA) correlate well with the polar components of surface free energies. On the basis of the measurements of swelling ratio and initial modulus, the interfacial bonding through highly crosslinked polymeric shell formation around the nitramine particles and generating interfacial reinforcement were rationalized. The application of Tapping Mode AFM (atomic force micro scope) to observing the surface morphology of NPBA reveals that methyl acrylate monomer appears to play a role for aiding the formation of network like structure when nanometer scale images of NPBA are created.

Three Dimensional Kinematics Analysis of the Independent Suspension Multibody System

Chen Xin, Lin Yi, Sun Dagang, Bai Wenhui

1997, 6(4): 376-382.

[Abstract](201)

Abstract:
Based on the theory of multibody system dynamics, the spatial kinematics analysis of the Mcpherson independent suspension widely used in the car was carried out. A practical and simpler method was provided to reduce the number of the generalized coordinates and constraint functions. By solving the nonlinear equations, the motion of any points in the whole suspension and wheel system can be predicted, including the spatial changes of the wheel alignment parameters which are of great importance to the car performances.

1997 Vol. 6, No. 4