JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Design of the Testing System for Jet Elements

YAO Xiao xian, MO Bo, LI Heng biao

2002, 11(3): 225-228.

[Abstract](176) [PDF 147KB](3)

Abstract:
To analyze the errors of processing data, the testing principle for jet elements is introduced and the property of testing system is theoretically and experimentally studied. On the basis of the above, the method of processing data is presented and the error formulae, which are the functions of the testing system property, are derived. Finally, the methods of reducing the errors are provided. The measured results are in correspondence with the theoretical conclusion.

Synergy Decision for Radar and IRST Data Fusion

DOU Li hua, YANG Guo sheng, CHEN Jie, HOU Chao zhen

2002, 11(3): 229-233.

[Abstract](213)

Abstract:
A new synergy decision method for radar and infrared search and track (IRST) data fusion is proposed, to solve such problems as how to decrease opportunities for radar suffering from being locked on by adverse electronic support measures (ESM), how to retrieve range information of the target during radar off, and how to detect the maneuver of the target. Firstly, polynomials used to predict target motion states are constructed. Secondly, a set of discriminants for detecting target maneuver are established by comparing the predicted values with the observations from IRST. Thirdly, a set of decisions are presented. Lastly, simulation is performed on the given scenario to test the validity of the method.

Initial Alignment Technique for SINS of Vehicles in the Moving State

MIAO Ling juan, SHEN Jun, LIU Wei, YANG Yong

2002, 11(3): 234-239.

[Abstract](291)

Abstract:
An initial alignment technique for the strapdown inertial navigation system (SINS) of vehicles in the moving state is researched. By selecting an odometer as the system's external sensor, the mathematical model for the alignment in the moving state is established and the observability of the system is analyzed. The results show that the SINS can successfully achieve the precision alignment in 10 min when the vehicle is moving toward the prearranged place after its staying for several seconds to perform the coarse alignment. The precision of alignment can also be improved in the moving state compared with that in the static state.

Pulse Quick Charger of Electric Vehicle

ZHANG Cheng ning, WU Bing feng, SUN Feng chun, ZHANG Wang

2002, 11(3): 240-245.

[Abstract](192)

Abstract:
In order to improve the charging efficiency of lead acid battery, shorten the charging time and avoid the battery polarization, a new charging method was put forward. Based on the analyzed results of charging characteristic of lead acid battery, a pulse quick charger is designed to adjust the charging current pulse's amplitude and pulse width automatically stage by stage according to the measured battery voltage and feedback current. Compared with other kinds of quick chargers, it has such characteristics as shorter charging time, higher charging efficiency and lower temperature increasing during the charging process. As a result, the battery polarization is reduced efficiently.

Multidimensional Modeling of Fuel Spray, Combustion and Emissions of F912Q Diesel Engine

WANG Ke, ZHANG You tong

2002, 11(3): 246-250.

[Abstract](154) [PDF 208KB](2)

Abstract:
A computational fluid dynamics (CFD) study was carried out on a four stroke air cooled DI diesel engine, F912Q manufactured by Beinei Company, by using the KIVA 3V code. A three dimensional mesh was set up to model the cylinder, intake passage and exhaust passage. The calculated in cylinder pressure history and emissions are compared with the engine test data. The results show reasonable agreement. The effects of swirl ratio and spray angle on fuel spray, evaporation and mixing are investigated. It is found that there are optimum swirl ratio and spray angle for better evaporation and combustion.

Monitoring Longitudinal Vehicular Velocity by Using Driving Wheels Information

BIAN Ming yuan, SUN Feng chun, CHEN Si zhong, LI Jun

2002, 11(3): 251-255.

[Abstract](97)

Abstract:
In order to enhance the accuracy and overcome the limitation of representing the vehicular velocity with non driving wheel speed signals, which is commonly used in researching on automotive dynamic control systems at present, the dynamic and kinematics models of running vehicles and wheels are established. The concept that expresses vehicle velocity using only the driving wheel speed information with adjustable weight factors is described and an algorithm is proposed. A Matlab program with the algorithm embedded is made to simulate the vehicle's accelerating under different road conditions, and it's simulation results coincide well with the experimental results, which demonstrates the validity of the algorithm.

Calibration Scheme Under Spherical Coordinates for Magnetic Tracker Used in VR System

XU Tong, LIU Li ping, LIU Yue, WANG Yong tian

2002, 11(3): 256-258.

[Abstract](166)

Abstract:
A calibration scheme under spherical coordinates is described for a magnetic tracker used in VR (virtual reality) system. A look up table containing data of tracked values for certain positions in the working space, spe cified in spherical coordinates, is generated first, which is then used to calibrate the tracking results by a two dimensional interpolation. The scheme can effectively correct the static errors in the magnetic tracking system. The employment of spherical coordinates significantly reduces the calculation complexity in calibration.

To Improve the Accuracy of Laser Pulse Range Finding by Time Scale-Up

YIN Cong, HAN Shao kun, LIU Xun liang, ZHANG Hua peng, ZHAO Yue jin

2002, 11(3): 259-262.

[Abstract](176)

Abstract:
A method of improving the accuracy of laser pulse range finding from ±10 m to ±1 m inexpensively by means of time scale up is described. Time scale up can stretch the entire flight time by a factor of 1 000 and then the stretched result is counted to calculate the distance. The use of this technique decreases the resolution of counting from nanosecond to microsecond, therefore a separate counting oscillator followed by an interpolation operation is unnecessary. This technique can improve the accuracy of laser pulse range finding inexpensively and effectively.

Targets Track Predicting of IR Image by CMAC

SHI Cai cheng, ZHAO Bao jun, MAO Er ke, HE Pei kun

2002, 11(3): 263-265.

[Abstract](177)

Abstract:
The centroid and attitude of target must be predicted in target tracking of IR image for increasing capture probability. CMAC estimator can effectually resolve conflict between operational counts and predicting precision. CMAC estimator is trained with a linear model, then the centroid and attitude are predicted. It is trained once by actual error in each frame to reduce the estimate error. CMAC has excellent predicting precision and small operational counts, it adapts to real time processing for target tracking. The experimental results show that CMAC can accurately estimate the centroid and attitude of target. It adapts to change of model and has robustness.

Comparative Study on VQ-Based Efficient Mandarin Speech Recognition Method

XIE Xiang, ZHAO Jun hui, KUANG Jing ming

2002, 11(3): 266-270.

[Abstract](169)

Abstract:
A VQ based efficient speech recognition method is introduced, and the key parameters of this method are comparatively studied. This method is especially designed for mandarin speaker dependent small size word set recognition. It has less complexity, less resource consumption but higher ARR (accurate recognition rate) compared with traditional HMM or NN approach. A large scale test on the task of 11 mandarin digits recognition shows that the WER(word error rate) can reach 3 86%. This method is suitable for being embedded in PDA (personal digital assistant), mobile phone and so on to perform voice controlling like digits dialing, name dialing, calculating, voice commanding, etc.

Signal and Data Processing of Television Based on Multistatic Radar Systems

LI Shuo, ZENG Tao, LONG Teng

2002, 11(3): 271-275.

[Abstract](148)

Abstract:
A television based multistatic radar system is described. The commercial television transmitter is used as the illuminator in the multistatic radar system. The reflected commercial television signals are measured by an array of sensors. A data processing scheme is developed that adapts to the poor signal processing ability. The innovation is focused on the construction of the observation space, which could reduce the non linearity error. The new method leads to better system stability than the traditional one. Monte Carlo simulation is utilized and compared with the traditional method.

Method of Jamming C/A Code GPS Receiver

HAN Li, XIE Zheng

2002, 11(3): 276-279.

[Abstract](161)

Abstract:
The schemes and effects of electronically jamming GPS's C/A code receivers are studied by using CW as the narrow band jamming signal and BPSK signal modulated by Gold code which is incoherent to that adopted by GPS as the wide band one. By simulating with Monte Carlo method and programming in Matlab language, the various jamming results in terms of bit error rate under several jamming scenarios are obtained. Through analyzing the simulation results and quantitative dependences of jamming effects on the distance from jammer to GPS receiver and the jammer's height over ground, it is concluded that jamming with wide band jammer is much more effective than that with narrow band one.

Molecular Design and Electronic Structure Investigation of Novel Nitrogen Heteroatom 2-β-Naphthylbenzoxazoles

SUN Jing guo, FENG Yu ling, YAO Guo wei

2002, 11(3): 280-284.

[Abstract](295)

Abstract:
For the aim of finding new available functional materials, a series of nitrogen heteroatom 2 β naphthylbenzoxazole molecules were designed based on the experiment and theoretical studies of 2 β naphthylbenzoxazole molecule. Geometry optimization of the 2 β naphthylbenzoxazole was carried out by using Hyperchem Molecular Mechanics plus MM+. The planar molecular structure was obtained. The quantum chemistry calculating method PPP SCF CI, which is specially available to treat electron spectrum, was applied to investigate each novel designed molecules. Their electronic structures were analyzed in detail, it shows that total π electron energy decreased linearly with the number of replaced nitrogen. Single nitrogen atom located in benzoxazole ring or naphthalene ring results in contrary changes of level difference of FMO; multiple nitrogen atoms located in different molecular positions will lead to polarization of extremum in the level difference of FMO; and 5 nitrogen heteroatoms reach the culmination. Considering other electronic structure information, some favorable designed molecules were identified.

Separation Properties of a New Polysiloxane-Anchored β-Cyclodextrin Derivative as Gas Chromatography Stationary Phase

SHI Xue yan, FU Ruo nong, GU Jun ling

2002, 11(3): 285-289.

[Abstract](125) [PDF 169KB](5)

Abstract:
A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3')) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.

Ozonation and Biodegradability of Lignin in Water

LI Yu ping, Gorenflo A, Frimmel F H

2002, 11(3): 290-294.

[Abstract](120)

Abstract:
To convert the non biodegradable sodium lignin sulfonate into biodegradable substances, the sodium lignin sulfonate in the water was ozonized and the pH value, dissolved organic carbon(DOC), ultraviolet absorbency at λ =254 nm(UVA) and the biodegradability of the ozonation effluent were measured. The non biodegradable sodium lignin sulfonate can be partly converted into biodegradable substances by ozonation (about 38 76%). In the ozonation process, there is little DOC decrease, but much UVA decrease and obvious pH drop.

Analysis and Modeling of the Central Air-Conditioning System in Intelligent Buildings

GUO Qiao, XU Qing wei

2002, 11(3): 295-297.

[Abstract](162) [PDF 115KB](4)

Abstract:
The central air conditioning system in an intelligent building (IB) was analyzed and modeled in order to perform the optimization scheduling strategy of the central air conditioning system. A set of models proposed and a type of periodically autoregressive model (PAR) based on the improved genetic algorithms (IGA) were used to perform the optimum energy saving scheduling. The example of the Liangmahe Plaza was taken to show the effectiveness of the methods.

Optimum Energy Management of the Central Air-Conditioning System in Intelligent Buildings

GUO Qiao, XU Qing wei

2002, 11(3): 298-301.

[Abstract](158)

Abstract:
An optimum energy saving scheduling strategy of the central air conditioning system in an intelligent building (IB) was proposed. Based on the system analysis a set of models of the central air conditioning system was established. The periodically autoregressive models (PARM) based on genetic algorithms (GA) were used to predict the next day's cold load. The improved genetic algorithms (IGA) with stochastic real number coding were used to finish the optimum energy saving scheduling of the system. The simulation results for the building of the Liangmahe Plaza show that the proposed strategy can save energy up to about 24 5%.

FE Method of Analysing Detecting Electrode of Capacitance Proximity Fuze

CHENG Shun, CUI Zhan zhong, ZHANG Xu dong

2002, 11(3): 302-305.

[Abstract](197)

Abstract:
The finite element method is first introduced into the design process of detecting electrodes of three electrode capacitance fuze, the mutual capacitance of the fuze and target is calculated by the finite element method, which provides the parameters for simulation circuit and design of detecting electrode. The finite element method pierces the traditional method of designing detecting electrode-design, test and adjustment. The system capacitance can be calculated accurately and the performance can be predicted in the design period of the detecting electrode, which saves a lot of research fee. The capacitances of a mortar shell fuze above ground 2 m and lower are given. After putting the computing data into simulating circuit, the demodulation voltage can be obtained, its changing trend is in agreement with the tested result.

Application of Predictive Algorithm in Head-Tracking System

JIANG Ming, LI Ke jie, LI Xin

2002, 11(3): 306-310.

[Abstract](186)

Abstract:
The worldwide research status of head tracking is introduced and the works made in the research of the predictive algorithm and in the exploration of the rule of the head tracking are set forth. A time delay model for the telerobotic scout system is built. In respect of eliminating error caused by time delay and making reasonable prediction to the data stream, many methods are experimented in order to realize the aim of real time tracking. The application of extrapolation algorithm and auto recursive algorithm in the orientation tracking is described in detail. These two algorithms are realized in Matlab environment. Through analysis of the curves generated by using these two predictive algorithms, an appropriate method was applied in the telerobotic scout system. The effect is satisfying.

Method of Establishing Object-Oriented System Structure for Decision Support System

CAO Yuan da, HU Jun, GUAN Chun

2002, 11(3): 311-315.

[Abstract](172)

Abstract:
In order to solve existing problems about the method of establishing traditional system structure of decision support system(DSS), O S chart is applied to describe object oriented system structure of general DSS, and a new method of eight specific steps is proposed to establish object oriented system structure of DSS by using the method of O S chart, which is applied successfully to the development of the DSS for the energy system ecology engineering research of the Wangheqiu country. Supplying many scientific effective computing models, decision support ways and a lot of accurate reliable decision data, the DSS plays a critical part in helping engineering researchers to make correct decisions. Because the period for developing the DSS is relatively shorter, the new way improves the efficiency of establishing DSS greatly. It also makes the DSS of system structure more flexible and easy to expand.

Design and Implementation of an Open Network Security Management Platform

CAO Yuan da, WANG Yong

2002, 11(3): 316-320.

[Abstract](166)

Abstract:
In order to manage all kinds of network security devices and software systems efficiently, and make them collaborate with each other, the model for an open network security management platform is presented. The feasibility and key implementing technology of the model are expatiated. A prototype system is implemented to validate it.

Oscillation in a Class of Neutral Differential Equations with Positive and Negative Coefficients

SHAN Wen rui, GE Wei gao, GUO Yan ping

2002, 11(3): 321-324.

[Abstract](175)

Abstract:
The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.

Existence of Periodic Solutions for Generalized Liénard-Typed Functional Differential Equations

HE Xiao ming, GE Wei gao, SHAN Wen rui

2002, 11(3): 325-328.

[Abstract](137)

Abstract:
The existence of periodic solutions for a kind of generalized Liénard typed functional differential equation is studied. By means of the continuation theorem of coincidence degree theory, existence criteria are established for the existence of periodic solutions and some previous results are extended.

Form Invariance of Routh Equations

WANG Shu yong, MEI Feng xiang

2002, 11(3): 329-331.

[Abstract](151)

Abstract:
The form invariance of Routh equations in holonomic systems is studied. The definition and criterion for the form invariance under the infinitesimal transformations are given. The relation of the form invariance with the Noether symmetry and the Lie symmetry is discussed.

Effects of Spark Ignition Engine Operating Parameters on Its Cyclic Variation ——Modeling and Simulation

JI Chang wei

2002, 11(3): 332-336.

[Abstract](181)

Abstract:
An engine cyclic variation model has been built by using the residual gas temperature for the n th cycle as the input of the model, through constant pressure intake process, adiabatic compression process, constant volume combustion process, adiabatic expansion process, adiabatic blow down process and constant pressure exhaust process to approximate the thermodynamic processes in the cylinder, finally the residual gas temperature for the ( n+1) th cycle can be estimated. Because of the adding of engine operating parameters such as engine speed, spark advance, equivalence ratio, intake air pressure, intake air temperature to the model, effects of these parameters on cyclic variation can be estimated quantitatively. Since residual gas temperature fluctuation between cycles reflects the circumstances of engine cyclic variation, parameters to which residual gas temperature is sensitive are most likely used as the means to control cyclic variation. Model simulation shows that for the nearly stiochiometric mixture, cyclic variation is not obvious or even quite stable, but for the lean mixture, under the circumstances of partial load and larger spark advances, engine cyclic variations occur chaotically or with bifurcation.

2002 Vol. 11, No. 3