JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Application of Fractal Theory in Simulation of Ferromagnetic Elements' Hysteresis Loop in Transformer

BI Jun, FU Meng yin, ZHANG Yu he

2003, 12(2): 113-118.

[Abstract](63)

Abstract:
The simulation of the transformer transient is one of the indispensable qualifications for improving the performance of transformer protection, the key technique of the transformer's transient simulation is the treatment of ferromagnetic elements' loop. Thus the shapes of the primary hysteresis loop and each internal secondary hysteresis loop in the identical magnetism conducting are analyzed, and then it is proposed that there are some fractal characteristics in the relation between them. The fractal phenomenon of the ferromagnetic elements' hysteresis loop in the transformer's transient simulation is first brought forward, the mutuality between the ferromagnetic elements' primary hysteresis loop and its secondary hysteresis loops is revealed in mechanism by using the fractal theory. According to the iterated function system of fractal theory, the secondary hysteresis loops can be generated by the iterative calculation of the primary loop. The simulation results show the validity of this idea.

A Kind of Second-Order Learning Algorithm Based on Generalized Cost Criteria in Multi-Layer Feed-Forward Neural Networks

ZHANG Chang jiang, FU Meng yin, JIN Mei

2003, 12(2): 119-124.

[Abstract](197)

Abstract:
A kind of second order algorithm--recursive approximate Newton algorithm was given by Karayiannis. The algorithm was simplified when it was formulated. Especially, the simplification to matrix Hessian was very reluctant, which led to the loss of valuable information and affected performance of the algorithm to certain extent. For multi layer feed forward neural networks, the second order back propagation recursive algorithm based generalized cost criteria was proposed. It is proved that it is equivalent to Newton recursive algorithm and has a second order convergent rate. The performance and application prospect are analyzed. Lots of simulation experiments indicate that the calculation of the new algorithm is almost equivalent to the recursive least square multiple algorithm. The algorithm and selection of networks parameters are significant and the performance is more excellent than BP algorithm and the second order learning algorithm that was given by Karayiannis.

MTF Measurement of EBCCD Imaging System by Using Super Resolution Technique

ZUO Fang, GAO Yue, GAO Zhi yun, SU Mei kai, ZHOU Li wei

2003, 12(2): 125-128.

[Abstract](191)

Abstract:
Existing methods of measurement MTF for discrete imaging system are analysed. A slit target is frequently used to measure the MTF for an imaging system. Usually there are four methods to measure the MTF for a discrete imaging system by using a slit. These methods have something imperfect respectively. But for the discrete imaging systems of under sampling it is difficult to reproduce this type of target properly since frequencies above Nyquist are folded into those below Nyquist, resulting in aliasing effect. To tackle the aliasing problem, a super resolution technique is introduced into our measurement, which gives MTF values both above and below Nyquist more accurately.

Novel Closed-Form Solution for Analyzing Mutual Coupling Between Cylindrical Comformal Rectangular Microstrip Patch Antennas

HE Mang, XU Xiao wen

2003, 12(2): 129-133.

[Abstract](147)

Abstract:
Based on the integral equation formulations and the moment method, a novel closed form solution for analyzing the mutual coupling effect between the cylindrical comformal rectangular microstrip patch antennas is presented. By using this algorithm, the elements of the impedance matrix and exciting vector are cast into closed forms, thus the computational efficiency is improved dramatically. Numerical results are presented to verify the validity and reliability of the algorithm.

DWT-Based Watermarking Scheme for Digital Images

HE Quan, SU Guang chuan

2003, 12(2): 134-137.

[Abstract](72)

Abstract:
A watermarking scheme for digital images is introduced. This method is based on discrete wavelet transform and spread spectrum technique. A discrete wavelet transformed binary signature image is expanded by an m sequence and added to the large wavelet coefficients of a host image with a scale factor. Good balance between transparency and robustness is achieved by the selection of the scale factor. In addition, the spread spectrum technique is adopted to increase the robustness of this watermarking scheme. The experimental results show that the proposed method is of good performance and robustness for common image operations such as JPEG lossy compression, etc.

Generating IDS Attack Pattern Automatically Based on Attack Tree

XIANG Ga, CAO Yuan da

2003, 12(2): 138-142.

[Abstract](182)

Abstract:
Generating attack pattern automatically based on attack tree is studied. The extending definition of attack tree is proposed. And the algorithm of generating attack tree is presented. The method of generating attack pattern automatically based on attack tree is shown, which is tested by concrete attack instances. The results show that the algorithm is effective and efficient. In doing so, the efficiency of generating attack pattern is improved and the attack trees can be reused.

Dynamic Factor Method of Computing Dynamic Mathematical Model for System Simulation

LAO Da zhong, WU Juan, YANG Ce, JIANG Zi kang

2003, 12(2): 143-148.

[Abstract](173)

Abstract:
The computational methods of a typical dynamic mathematical model that can describe the differential element and the inertial element for the system simulation are researched. The stability of numerical solutions of the dynamic mathematical model is researched. By means of theoretical analysis, the error formulas, the error sign criteria and the error relationship criterion of the implicit Euler method and the trapezoidal method are given, the dynamic factor affecting the computational accuracy has been found, the formula and the methods of computing the dynamic factor are given. The computational accuracy of the dynamic mathematical model like this can be improved by use of the dynamic factor.

Ecolifter Conceptual Configuration Design and Parameter Analysis

TANG Sheng jing

2003, 12(2): 149-153.

[Abstract](183) [PDF 172KB](2)

Abstract:
In the phase of conceptually designing, the Ecolifter with three lift surface configuration, the influences of aircraft geometric parameters and configuration such as wing geometric parameters, canard parameters, aircraft center of gravity and engine positions and so on, on flight dynamic stability are discussed with the integrated analysis method. On the basis of the analysis of flight dynamic stability, the suitable wing geometric parameters are given and the improved aircraft configuration is proposed.

Determination of Grüneisen EOS of MSN Alloy Steel Under High Pressure

XIE Jiu lin, ZHANG Qing ming, WANG Xiao ying, LIU Yan

2003, 12(2): 154-157.

[Abstract](233) [PDF 193KB](3)

Abstract:
Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.

Electronically Controlling the System of Preheating Intake Air by Flame for Diesel Engine Cold-Start

DU Wei, ZHAO Fu tang

2003, 12(2): 158-161.

[Abstract](171)

Abstract:
In order to improve the cold start performance of heavy duty diesel engine, electronically controlling the preheating of intake air by flame was researched. According to simulation and thermodynamic analysis about the partial working processes of the diesel engine, the amount of heat energy, enough to make the fuel self ignite at the end of compression process at different temperatures of coolant and intake air, was calculated. Several HY20 preheating plugs were used to heat up the intake air. Meanwhile, an electronic control system based on 8 bit micro controller unit (MCS 8031) was designed to automatically control the process of heating intake air. According to the various temperatures of coolant and ambient air, one plug or two plugs can automatically be selected to heat intake air. The demo experiment validated that the total system could operate successfully and achieve the scheduled function.

Finite Element Analysis for the Structure Optimization Design of the CPUE Load-Bearing Wheel of Tracked Vehicle

YU Li biao, ZHENG Mu qiao, ZHANG Ying

2003, 12(2): 162-165.

[Abstract](166)

Abstract:
A new kind of material cast polyurethane elastomers (CPUE) is introduced to take the place of rubber on load bearing wheel for the first time. Based on load bearing wheel dimensions, material properties and operating conditions, the structure of wheel flange is optimized by zero order finite element method. A detailed three dimensional finite element model of flange of load bearing wheel is developed and utilized to optimize structure of wheel flange. Its service life, which is affected by flange structure parameter, is analyzed by comparing the optimization results with those of prototype of wheel. The results of optimization are presented and the stress field of load bearing wheel in optimal dimension obtained by using finite element analysis method is demonstrated. The finite element analysis and optimization results show that the CPUE load bearing wheel is feasible and suitable for the tracked vehicle and has a guiding value in practice of the weighting design of the whole tracked vehicle.

Basic Problems in Design and Inverse Engineering Solution for Outer Characteristic of Vehicle Suspension Shock Absorbers

YU De fu, CHEN Qing dong, LI Wen jun

2003, 12(2): 166-171.

[Abstract](158)

Abstract:
Based on the theory and the practical experiences of linearity design of feasible design area and inverse solution of non linear outer characteristic of suspension shock absorber, in accordance with non linearity outer characteristic formed by open up damping coefficient, full open damping coefficient and smoothness to safety ratio of suspension shock absorber, a method and a research conclusion of the feasible design and inverse solution for the basic problems of designing and inverse solution of non linear outer characteristic of suspension damping components are provided.

Numeric Simulation of Single Passage Ternary Turbulence Model in Hydraulic Torque Converter

YAN Qing dong, WEI Wei

2003, 12(2): 172-175.

[Abstract](176)

Abstract:
Based on the renormalization group theory, a hydraulic torque converter 3 D turbulent single flow passage model is constructed and boundary condition is determined for analyzing the influence of the fluid field characteristic and parameters on the macroscopic model. Numerical simulation of the single fluid path is processed by computational fluid dynamics and the calculated results approach to experimental data well, and especially in low transmission ratio the torque and head results are more close to experimental data than the calculated results of beam theory. This shows that the appropriate ternary analysis method and reasonable assumption of boundary condition may analyze the flow field more precisely and predict the performance of torque converter more accurately.

Heat Resistance of TiN Coated HSS Tools

ZHOU Lan ying, ZHOU Huan lei, JIA Qing lian

2003, 12(2): 176-179.

[Abstract](73)

Abstract:
The cutting friction, cutting deformation, producing heat, conducting heat, temperature field of TiN coated HSS tools in the cutting process are discussed profoundly. In order to make clear the heat property of TiN coated tools, from the micromechanism angle, the relationship of the heat property and the crystal structure of TiN compound is analyzed, and the regularity of TiN compound crystal structure changing with temperature rising is sought. The difference of the wear resistance and heat resistance of TiN coated tools deposited by c1 and c2 depositing techniques is proved by tests. The conclusions will offer the theoretical basis for correct design of geometrical parameters of TiN coated tools, rational selection of cutting regimes and optimization of the depositing technique.

Constructing the Virtual Production Line

SUN Lian sheng, NING Ru xin

2003, 12(2): 180-182.

[Abstract](148)

Abstract:
In order to study the constructing technology of virtual production line, the structure model of virtual production line was presented, and the object oriented technique was used to establish its basic classes and relevant models, including solid model, behavior model and object oriented Petri net based control model, and based on this, the constructing of virtual production line was realized. The application proved that the virtual production line had many good characteristics, such as visualization, interaction, multi layer and reusability, and it's an efficient tool of analyzing and modeling for layout planning and rapidly reconfiguring of production line.

Method of Precision Control of 3-D Solid Discretization Based on the Second-Order Osculating Surface

WAN Xiao li, LIU Shu yan, YANG Meng chen, WANG Hong

2003, 12(2): 183-185.

[Abstract](162)

Abstract:
A discretization precision control method based on the second order osculating surface is proposed. The discretization precision of 3 D solid is controlled according to the error between the discrete solid surface and its second order osculating surface. The global maximal error has been gotten after analyzing all the extremums of the error function. It can be used in controlling and optimizing the discretization precision of 3 D solid in computer 3 D modeling and NC milling path generation.

Beckmann Rearrangement of Erythromycin A 9(E)-Oxime

DENG Zhi hua, YAO Guo wei, OU Yu xiang

2003, 12(2): 186-189.

[Abstract](199)

Abstract:
Deoxo 6 deoxy 6,9 epoxy 9,9 a didehydro 9 a aza 9 a homoerythromycin A (1), 9 deoxo 11 deoxy 9,11 epoxy 9,9 a didehydro 9 a aza 9 a homoerythromycin A (2) and 9 a aza 9 a homoerythromycin cyclic lactam (3) were synthesized by the Beckmann rearrangement of erythromycin A 9 (E) oxime (4). The structures of compounds (1), (2) and (3) have been identified by their spectral data. The reaction mechanism was also discussed. The yield of the Beckmann rearrangement of compounds (4) was better than that reported in literatures.

Ab Initio and DFT Study of Magnesium Sulfate Contact Ion Pairs

ZHANG Xing chen, ZHANG Yun hong, LI Qian shu

2003, 12(2): 190-193.

[Abstract](94)

Abstract:
The stuctures of contact ion pairs of magnesium sulfate were studied. The geometries of contact ion pairs of MgSO 4(H 2O) n (n =1-6) were optimized by using Hartree Fock (HF/6 31+G *, HF/6 311+G ** ) and density functional theory (DFT) (B3LYP/6 31+G *, B3LYP/6 311+G ** ) methods. The stable structures of monodentate, bidentate and tridentate contact ion pairs were obtained. The bidentate structure of contact ion pairs are the most stable compaired with the monodentate and tridentate ones for the same composition. The hydration enthalpies of contact ion pairs of MgSO 4 (H 2O) n (n =1-4) increase with their hydration numbers.

HPLC Method for the Determination of Tamsulosin Hydrochloride in Sustained Release Tablets

QI Mei ling, WANG Peng, GENG Ying shu, GU Jun ling

2003, 12(2): 194-197.

[Abstract](126)

Abstract:
The development and validation of an isocratic high performance liquid chromatographic method is described for the determination of tamsulosin hydrochloride in sustained release tablets. The determination was performed on a Diamonsil BDS C18 column with a mobile phase consisting of a mixture of acetonitrile, methanol and 0 5% phosphoric acid solution (20∶30∶50, V/V/V ) at a flow rate of 1 0 mL/min. UV detection was made at 274 nm. The linear range for tamsulosin hydrochloride was 0 81-8 10 μg/mL. The mean recovery was 99 8% ( S R=0 7%, n =9), and the precision was found to be 0 45% ( n =9). The proposed method can be used for routine analysis of tamsulosin hydrochloride in sustained release tablets.

Gaussian Functions,Γ-Functions and Wavelets

CAI Tao, XU Tian zhou

2003, 12(2): 198-201.

[Abstract](216)

Abstract:
The relations between Gaussian function and Γ function is revealed first at one dimensional situation. Then, the Fourier transformation of n dimensional Gaussian function is deduced by a lemma. Following the train of thought in one dimensional situation, the relation between n dimensional Gaussian function and Γ function is given. By these, the possibility of arbitrary derivative of an n dimensional Gaussian function being a mother wavelet is indicated. The result will take some enlightening role in exploring the internal relations between Gaussian function and Γ function as well as in finding high dimensional mother wavelets.

On Minus Paired-Domination in Graphs

XING Hua ming, SUN Liang

2003, 12(2): 202-204.

[Abstract](119)

Abstract:
The study of minus paired domination of a graph G=(V,E) is initiated. Let SV be any paired dominating set of G , a minus paired dominating function is a function of the form f∶V→{-1,0,1} such that f(v)= 1 for v∈S, f(v)≤0 for v∈V-S , and f(N)≥1 for all v∈V . The weight of a minus paired dominating function f is w(f)=∑f(v) , over all vertices v∈V . The minus paired domination number of a graph G is γ - p( G )=min{ w(f)|f is a minus paired dominating function of G }. On the basis of the minus paired domination number of a graph G defined, some of its properties are discussed.

Iteration of the Composition of Entire Functions

FANG Li ping

2003, 12(2): 205-207.

[Abstract](99)

Abstract:
Let P(z) be entire and g(z)=λ e z, λ∈C-{0}. If f=P(g) has no wandering domain, then neither does h=g(P) . The normal sets of h=g(P) and f=P(g) have no Baker domain at the same time.

Stability of the Bifurcation Solutions for a Predator-Prey Model

MENG Yi jie, WANG Yi fu

2003, 12(2): 208-211.

[Abstract](251)

Abstract:
The bifurcation solution of the nonnegative steady state of a reaction diffusion system was investigated. The combination of the sturm type eigenvalue and the theorem of bifurcation was used to study the local coexistence solutions, and obtain the stability of bifurcation solutions. The system model describes predator prey interaction in an unstirred chemostat.

Convergence Diagnostics for Gibbs Sampler via Maximum Likelihood Estimation

CHENG Qi yuan, LIN Xiu guang

2003, 12(2): 212-215.

[Abstract](155)

Abstract:
A diagnostic procedure based on maximum likelihood estimation, to study the convergence of the Markov chain produced by Gibbs sampler, is presented. The unbiasedness, consistent and asymptotic normality are considered for the estimation of the parameters produced by the procedure. An example is provided to illustrate the procedure, and the numerical result is consistent with the theoretical one.

Underwater Distribution Field of Laser Through Wavy Surface of Water

MA Yong, YANG Ke cheng, LIN Jin zhang

2003, 12(2): 216-219.

[Abstract](153)

Abstract:
Aimed at the properties of the absorption and the scattering of photons in the water, the process of simulating by Monte Carlo method is analyzed. According to the slope distribution of wavy surface of water, the distribution field of underwater laser is simulated, and some conclusions about the distribution field of laser through wavy surface in two different conditions are obtained. The characteristics of the distribution of laser in the seawater at the same depth with different water qualities and in the seawater at different depths with the same water quality are computed. The results are significant to the design of airborne oceanic lidar.

Methods for the Gear-Position Decision in AMT

SUN Yi ze, XIONG Wei, YAO Yu feng

2003, 12(2): 220-224.

[Abstract](184)

Abstract:
Aimed at defects of the gear position decision in an automatic mechanical transmission, a method of synthetic shift schedule of 5 speed gear position is presented, which is based on the fuzzy discernment of the driver intention and the road characteristics. A contrastive experimental analysis between the synthetic gear position decision method and the traditional gear position decision method is given by analyzing Santana 2000.

2003 Vol. 12, No. 2