JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Design of No-Steady-Error and Anti-Disturbance Controller for Vehicular Servo Systems

SUN Chang-sheng, LIANG Yu, CHEN Jie, DOU Li-hua, MA Yan-feng

2002, 11(4): 337-341.

[Abstract](166)

Abstract:
A modified method of design of no-steady-error and anti-disturbance controller is proposed for the design of tank stabilizers. Using a reduced-order observer to estimate its mode, disturbance can be compensated. This enables the system to resist sinusoidal disturbance with any magnitude. Estimate of angular velocity is used as the state feedback to replace the expensive gyro and tachometer generator. The modified method excels the traditional, and provides a new way for the design of tank fire control system. It can also be applied for the design of other servo systems in vehicle and aircraft.

New Algorithm for Image Target Recognition Based on Fractal Feature Fusion

PAN Xiu-qin, HOU Chao-zhen, SU Li-min

2002, 11(4): 342-345.

[Abstract](186)

Abstract:
By combining fractal theory with D-S evidence theory, an algorithm based on the fusion of multi-fractal features is presented. Fractal features are extracted, and basic probability assignment function is designed. Comparison and simulation are performed on the new algorithm, the old algorithm based on single feature and the algorithm based on neural network. Results of the comparison and simulation illustrate that the new algorithm is feasible and valid.

Multipoint Infrared Telemetry System for Measuring the Piston Temperature in Internal Combustion Engines

LIU Jin-xiang, WEI Chun-yuan, ZHANG Wei-zheng, GUO Liang-ping

2002, 11(4): 346-349.

[Abstract](198)

Abstract:
A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into corresponding voltage signal by the thermo-couple first. Then after the V/F stage, the voltage signal is converted into the frequency signal to drive the infrared light-emitting diode to transmit infrared pulses. At the receiver end, a photosensitive audion receives the infrared pulses. After conversion, the voltage recorded by the receiver stands for the magnitude of temperature at the measuring point. Test results of the system indicate that the system is practical and the system can perform multipoint looping temperature measurements for the piston.

Design and Implementation of Programmable RS Codec Module in Satellite Communication Modem

ZOU Yi, WANG Hua, KUANG Jing-ming

2002, 11(4): 350-354.

[Abstract](202)

Abstract:
In the study and implementation of a programmable RS codec module in satellite communication modem, FPGA is used as the kernel in the implementation, while some ASICs are used as necessary assistant measures. The module includes the RS codec unit, the interleaver and deinterleaver unit, the scrambler and descrambler unit and the frame synchronization unit. The module is realized successfully and it can be programmed on-line to meet the requirements of IESS 308/309/310 including many specifications about different service types and data rates. With the implementation combining FPGA with ASICs, size of the circuit is much reduced, its flexibility dramatically increased, and its stability further strengthened. Furthermore, the module is based on the software radio concept and can be easily integrated into the whole satellite communication modem.

The FDTD Full Wave Analysis of Fractal Antennas

WANG Hong-jian, GAO Ben-qing

2002, 11(4): 355-359.

[Abstract](206)

Abstract:
The full wave FDTD method was used to analyze the Hilbert and H fractal curves antennas. The computational results of the input impedance of Hilbert fractal antenna are in good agreement with the experiments in the documents. The results also show that the self-similarity of the fractal structure leads to the multiplicity of resonances over some predetermined operating bandwidths of the antenna. Fractal geometries of Hilbert and H curves can be implemented to miniaturize the antenna, too. The results also show that the higher order fractal antenna leads to the more efficient reduction of the antenna size than the lower order one. Furthermore, the far field patterns remain almost the same as those of the dipole at their own resonant frequencies.

An Improved On-Chip CMOS Astable Multivibrator

CUI Wei, HAN Yue-qiu, CHEN He

2002, 11(4): 360-363.

[Abstract](804)

Abstract:
An improved on-chip CMOS astable multivibrator is proposed, which overcomes the shortcomings of the traditional one that the signal duty-cycle is depending on model parameters, and generates stable clock signal with duty-cycle equaling 50%. The latch-up effect has been prevented on the improved circuit. It is extremely important that all the excellent performances of the improved astable multivibrator have been achieved with a dynamic power consumption equaling its predecessor one. The advantage of the structure has been verified by SPICE simulation.

Full Wave Analysis of a Broad Wall Waveguide Slot Coupler

REN Wu, DING Si-ru, GAO Ben-qing

2002, 11(4): 364-368.

[Abstract](150)

Abstract:
A rigorous analysis of a broad wall slot coupler composed of two crossed rectangular waveguides by using FDTD method is presented. Two types of slots, a longitudinal/transverse slot and a centered-inclined slot, are analyzed. Coupling slot characteristics are obtained, including scattering parameters and the resonant length for different waveguide dimensions and frequencies. The numerical results are all in good agreement with those by the method of moments. A coupler system with a short circuit port is also analyzed to help designing the slot array.

Investigation of Adaptive Multi-Rate Link Adaptation of 3G System

FEI Ze-song, WAN Lei, ZHAO Sheng-hui, KUANG Jing-ming

2002, 11(4): 369-374.

[Abstract](153)

Abstract:
In term of the features of 3G system, a novel AMR link adaptation strategy for 3G system is proposed. The impacts of AMR codec modes and power control on traffic quality of service are taken into account in the strategy at the same time. By synthetically comparing the signal-to-interference ratio value with the switching threshold and comparing the transmission power with its threshold, radio resource management can always keep each link on its proper codec mode with the corresponding optimal power level to achieve both robust speech quality and link capacity enhancement. Based on the WCDMA FDD uplink link-level simulation platform, AMR link adaptation platform is constructed. Simulation results show that the algorithm can track the fast change of channel conditions and select the most robust codec mode, thus the synthetic speech quality of AMR is better than that of signal mode during a wide range of channel conditions. The result will provide a reference strategy for AMR link adaptation of 3G system.

A Facile Synthesis of 9-Amino-1,2,3,4- Tetrahydroacridine from Isatin

LI Jia-rong, ZHOU Xin-wo, CHEN Peng, GUO Yong-jian

2002, 11(4): 375-377.

[Abstract](200)

Abstract:
Tacrine(9-amino-1,2,3,4-tetrahydroacridine) was synthesized using isatin as the raw material through isatin 3-oxime and 2-aminobenzonitrile with a yield of 68.1%. Sodium methoxide was used as the catalyst in the thermal decomposition of isatin 3-oxime, and tetramethylene sulfone was used as the solvent. The structure of tacrine was determined by IR, 1H NMR, MS and elemental analysis.

Simultaneous Determination of Ticlopidine Hydrochloride and Nitrendipine in a New Tablet Formulation by HPLC

QI Mei-ling, WANG Peng, GU Jun-ling

2002, 11(4): 378-382.

[Abstract](161)

Abstract:
An accurate, simple and sensitive high performance liquid chromarographic (HPLC) method for simultaneous determination of ticlopidine hydrochloride and nitrendipine in a new tablet formulation is described. Chromatographic separation of ticlopidine hydrochloride and nitrendipine was achieved on a Hypersil BDS C18 column using a mobile phase consisting of acetonitrile-methanol-10 mmol/L ammonium acetate (60∶10∶30(V/V), pH 6.5) at a flow rate of 1.0 mL/min. Absorbance was monitored at 236 nm where both drugs have significant absorption. The proposed method was validated with respect to linearity, selectivity, accuracy, precision, and limits of detection and quantitation. The linear ranges for ticlopidine hydrochloride and nitrendipine were found to be 75-750 μg/mL and 1-10 μg/mL, respectively. The mean recoveries were 100.1%(S R=0.6%,n=9) for ticlopidine hydrochloride and 99.9%(S R=0.7%,n=9) for nitrendipine. The within-day precision and between-day precision for ticlopidine hydrochloride and nitrendipine were 0.63% and 0.89%, and 0.74% and 1.0%, respectively. The proposed HPLC method can be used for the simultaneous determination of both drugs in pharmaceutical preparations.

Flight Range Optimization of Extended Range Guided Munitions

XIA Qun-li, QI Zai-kang, LIN De-fu

2002, 11(4): 383-388.

[Abstract](158) [PDF 223KB](6)

Abstract:
By the study of extended range guided munitions (ERGM) trajectory characteristics, ERGM free-flight and glide trajectory characteristics are revealed and illustrated. On the basis of free-flight trajectory mathematical model, a two-parameter optimization problem of quadrant elevation and rocket ignition time is studied. Using the atmosphere mathematical model, the best glide-starting point of the downward trajectory is determined. With an optimal control mathematical model, the ERGM optimal glide trajectory is obtained.

A Ballistic Limit Analytical Model of Tungsten Ball Perforating Ceramic/Aluminum Composite Target

LI Ming, JIANG Chun-lan, WANG Zai-cheng

2002, 11(4): 389-392.

[Abstract](117)

Abstract:
From the experimental data on ceramic/aluminum composite target, the mechanism of tungsten ball impacting a ceramic/aluminum composite target has been studied. By analyzing the transition of energy in the process of impact, a simple ballistic limit analytical model of tungsten ball impacting a ceramic/aluminum composite target has been proposed; and the result taken from this model is consistent with that of the experiment.

Method of Testing of Dynamic Forces on Digital Jet Elements

MO Bo, YANG Cai-xia

2002, 11(4): 393-396.

[Abstract](177)

Abstract:
Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.

Visualization of 3-D Field of Explosion

SUN Juan, NING Jian-guo

2002, 11(4): 397-400.

[Abstract](204)

Abstract:
In order to visualize the 3-D field of explosion and describe the complex physical phenomena of explosion, the 3-D data resulting from numerical simulation by 3-D multi-material in cell (MMIC), and the application of volume visualization is explored, based on the characteristics of explosion and shock. Based on this, a visualization system for 3-D explosion--ViSC3D is designed. Approaches for the visualization of 3-D field of explosion are presented. The algorithm and the functions of ViSC3D are also presented. ViSC3D is thus a useful tool to observe and analyze either the full picture or the details of a 3-D field of explosion, that are difficult to observe and analyze directly. With ViSC3D, the field of explosion between the hill slopes is visualized. The cutaway views and 2-D slices are also given. The full picture and partial details of 3-D field of explosion can be observed clearly. Furthermore, ViSC3D can be used to visualize other similar 3-D data fields.

An Analysis on the Motion Characteristics of Fuel and Shell in Launching

YAN Hua, ZHANG Qi, BAI Chun-hua

2002, 11(4): 401-404.

[Abstract](168)

Abstract:
The relative characteristics of motion of the fuel and shell upon launching is analyzed. By means of mechanical analysis and calculation, it is proposed that relative motion exists not only in the ranges between the fuel and shell of the warhead, but also in the fuel in different positions. The result of study indicates that the position of the fuel in the warhead has a marked influence on the relative motion, while the frictional coefficient between the fuel and shell has less influence upon it.

Application of ALE Method on the Numerical Simulation of Reinforced Concrete Penetration

WU Hai-jun, HUANG Feng-lei, ZHANG Qing-ming, CAO De-qing

2002, 11(4): 405-408.

[Abstract](169) [PDF 214KB](3)

Abstract:
LS-DYNA program and the principle of ALE method were introduced, and the target features of the reinforced concrete penetration were analyzed by using the D material model and the ALE method. A numerical simulation has been done to show the penetration visually and veritably. The simulation results are analyzed carefully and explicitly prove their significance to the research of reinforced concrete penetration.

A New Role Hierarchy Model for Role Based Access Control

LV Yi-hong, SONG Han-tao, GONG Yuan-ming

2002, 11(4): 409-413.

[Abstract](96)

Abstract:
A new role hierarchy model for RBAC (role-based access control) is presented and its features are illustrated through examples. Some new concepts such as private permission, public permission and special permission are introduced, based on the RRA97 model. Some new role-role inheriting forms such as normal inheritance, private inheritance, public inheritance and special-without inheritance are defined. Based on the ideas mentioned, the new role hierarchy model is formulated. It is easier and more comprehensible to describe role-role relationships through the new model than through the traditional ones. The new model is closer to the real world and its mechanism is more powerful. Particularly it is more suitable when used in large-scale role hierarchies.

Improvement of Fuzzy Inference Mechanism in FuzzyJ Toolkit

WU Qin-yi, CHEN Ying

2002, 11(4): 414-417.

[Abstract](159)

Abstract:
By applying the aggregation operator γ-operator and introducing a new method for global data contribution, the problems of information loss and the decrease of running efficiency in FuzzyJ Toolkit, an expert system shell, can be effectively solved. The example shows that the approach can overcome imprecision of max-operator and min-operator used during the process of fuzzy reasoning. Therefore, the information accuracy and the system performance can be effectively improved, which promotes the usability of FuzzyJ Toolkit.

The Application of Weighted Association Rules in Host-Based Intrusion Detection System

CAO Yuan-da, XUE Jing-feng

2002, 11(4): 418-421.

[Abstract](94)

Abstract:
Association rules are useful for determining correlations between items. Applying association rules to intrusion detection system (IDS) can improve the detection rate, but false positive rate is also increased. Weighted association rules are used in this paper to mine intrustion models, which can increase the detection rate and decrease the false positive rate by some extent. Based on this, the structure of host-based IDS using weighted association rules is proposed.

Exact Wave Function of a Time-Dependent Quantum System

PENG Yan-ze, PENG Song-qing, FAN Tian-you

2002, 11(4): 422-423.

[Abstract](152)

Abstract:
To solve the problem in dispute about a Schrdinger equation with time-depenelent mass and frequency, by means of a simple transformation of variables, the time-dependent Schrdinger equation is transformed into the time-independent one first and then an exact wave function can be found.

Percentiles Estimation for a Response Distribution

TIAN Yu-bin, MOU Ke-dian

2002, 11(4): 424-428.

[Abstract](181)

Abstract:
To estimate percentiles of a response distribution, the transformed response rule of Wetherill and Robbins-Monro sequential design were proposed under Log-Logistic model. Based on responses data, a necessary and sufficient condition for the existence of maximum likelihood estimators and then the calculating formula were presented. After a simulation study, the proposed approach was applied to 65# detonator. Numerical results showed that estimators of percentiles from the proposed approach are robust to the parametric models lacking information on the original response distribution.

Quantum Fluctuation Properties in Mesoscopic Josephson Junction

YANG Hu-jiang, SHAO Bin, ZOU Jian

2002, 11(4): 429-432.

[Abstract](190)

Abstract:
An effective bosonic Hamiltonian describing the interaction of a mesoscopic Josephson junction with a quantized radiation field is studied. It is shown that when the field is initially in a coherent state and the junction initially in its lowest energy level state, the state of the coupled field-mesoscopic Josephson junction system can evolve to a squeezed state. A detailed analysis about the quantum fluctuation of the coupled system is given.

KG₂over Rings with Division Rings of Quotients

CHEN Yi-hong, HAN Bing

2002, 11(4): 433-435.

[Abstract](100)

Abstract:
A presentation of hyperbolic unitary group is an important part in the unitary group. The group KG 2,n (R) plays an elementary role in presentation of unitary group. It is proved that KG 2,n(R)=1 for n≥2 over a ring R with division ring of quotients, using a new method, and a presentation of GE n(R) is given.

Lower Bounds on the Majority Domination Number of Graphs

LIU Hai-long, SUN Liang, TIAN He-min

2002, 11(4): 436-438.

[Abstract](240)

Abstract:
Let G=(V,E) be a simple graph. For any real valued function f∶V→R and SV, let f(S)=∑ u∈S?f(u). A majority dominating function is a function f∶V→{-1,1} such that f(N)≥1 for at least half the vertices v∈V. Then majority domination number of a graph G is γ maj(G)=min{f(V)|f is a majority dominating function on G}. We obtain lower bounds on this parameter and generalize some results of Henning.

Existence of Periodic Solutions of Nonlinear Neutral Differential Equation with Deviating Argument

REN Jing-li, GE Wei-gao

2002, 11(4): 439-443.

[Abstract](182)

Abstract:
Existence criteria is established for the periodic solution of the nonlinear neutral delay differential equation x′(t)=f(t,x(t),x(t-τ 1(t)),x′(t-τ 2(t)))+p(t) by means of an abstract continuous theorem of k-set contractive operator and some analysis technique.

Development of Fault Diagnosis System for Spacecraft Based on Fault Tree and G2

JI Chang-wei, RONG Ji-li

2002, 11(4): 444-448.

[Abstract](246) [PDF 235KB](3)

Abstract:
Some ideas in the development of fault diagnosis system for spacecraft are introduced. Firstly, the architecture of spacecraft fault diagnosis is proposed hierarchically with four diagnosis frames, i.e., system level, subsystem level, component level and element level. Secondly, a hierarchical diagnosis model is expressed with four layers, i.e., sensors layer, function layer, behavior layer and structure layer. These layers are used to work together to accomplish the fault alarm, diagnosis and localization. Thirdly, a fault-tree-oriented hybrid knowledge representation based on frame and generalized rule and its relevant reasoning strategy is put forward. Finally, a diagnosis case for spacecraft power system is exemplified combining the above with a powerful expert system development tool G2.

2002 Vol. 11, No. 4