JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Symmetrical Processing of Interferogram and Spectrum Reconstruction in Interference Spectrometer

2003, 12(1): 1-5.

[Abstract](203)

Abstract:
Because of its all-reflective layout based on the Fresnel double-mirror interference system, the newly developed Fourier transform imaging spectrometer has a very large spectral bandwidth ranged from a cut-off wavelength (related to the cut-off wave number σ max ) to far infrared. According to the signal's symmetry and wide-band characteristics, a simple method that can efficiently weaken the low frequency noise in the reconstructed spectrum is presented. Also, according to the symmetry, the eigenvector method is applied to the reconstruction of the spectrum.

New Imaging Spectrometric Method for Rotary Object

FANG Jun-yong, ZHAO Da-zun, JIANG Yue-juan, CHU Jian-jun

2003, 12(1): 6-10.

[Abstract](138)

Abstract:
A new technique for imaging spectrometer for rotary object based on computed-tomography is proposed. A discrete model of this imaging spectrometric system is established, which is accordant to actual measurements and convenient for computation. In computer simulations with this method, projections of the object are detected by CCD while the object is rotating, and the original spectral images are numerically reconstructed from them by using the algorithm of computed-tomography. Simulation results indicate that the principle of the method is correct and it performs well for both broadband and narrow-band spectral objects.

Characteristics Study of Portable Hand-Held Phone Antenna by MoM

LI Yu-ying, XU Xiao-wen

2003, 12(1): 11-14.

[Abstract](92)

Abstract:
The characteristics of one kind of handset antenna are analyzed by the method of moments. By using the Pocklington equation and the Galerkin method, the current distribution on the handset antenna is calculated, the input impedance and radiation patterns are obtained. In addition, the characteristics of monopoles mounted on conducting chassis box with different sizes are analyzed. The results show that the size of the conducting chassis box has significant effect on the performance of the handset antenna. Therefore, appropriately changing the size of the conducting chassis box may improve the performance of the handset antenna.

Editing Algorithms for Non-Linear Editing Systems Based on MPEG-2

LUO Sen-lin, GUO Shou-gang, YUAN Lu-jun, PENG Ze-shan

2003, 12(1): 15-18.

[Abstract](72)

Abstract:
MPEG-1/2-based non-linear editing systems appear to have a tendency to replace the M-JPEG systems, but in so doing it is difficult to realize the video, audio and the synchronization editing algorithms. Such editing algorithms are presented. Based on an analysis of the structure of the MPEG-1/2 stream, and using parameters of the video, audio and the synchronization information, the video, audio and synchronization editing algorithms are provided. The characters of the algorithms are efficient, the quality loss of frames is low because it only decodes and codes part of the data; the editing algorithm is fast through use of some index files; synchronization editing is realized using the synchronization information, such as PTS, ESCR and other parameters.

Application Research on Space Laser Communication in Bistatic Radar System

LI Xiao-ping, HAN Shao-kun, HAO Xiao-ning

2003, 12(1): 19-22.

[Abstract](189)

Abstract:
There exist three synchronizing problems in the bistatic radar system that some signals of the radar receiver must be synchronized with those of the radar transmitter. Several methods realizing data transmission, which are used to complete the synchronization existing in the bistatic radar system, are described. Then a new idea is brought forward that employs space laser communication in the bistatic radar system to realize its data transmission. The theoretic analysis of the idea's usability and its merits are discussed in details. Finally the latest development of space laser communication is introduced, and the utility of the idea is pointed out further.

Self-Organizing Genetic Algorithm Based Method for Constructing Bayesian Networks from Databases

ZHENG Jian-jun, LIU Yu-shu, CHEN Li-chao

2003, 12(1): 23-27.

[Abstract](102)

Abstract:
The typical characteristic of the topology of Bayesian networks (BNs) is the interdependence among different nodes (variables), which makes it impossible to optimize one variable independently of others, and the learning of BNs structures by general genetic algorithms is liable to converge to local extremum. To resolve efficiently this problem, a self-organizing genetic algorithm (SGA) based method for constructing BNs from databases is presented. This method makes use of a self-organizing mechanism to develop a genetic algorithm that extended the crossover operator from one to two, providing mutual competition between them, even adjusting the numbers of parents in recombination (crossover/recomposition) schemes. With the K2 algorithm, this method also optimizes the genetic operators, and utilizes adequately the domain knowledge. As a result, with this method it is able to find a global optimum of the topology of BNs, avoiding premature convergence to local extremum. The experimental results proved to be and the convergence of the SGA was discussed.

Extensible Markup Language Data Mining System Model

LI Wei, SONG Han-tao

2003, 12(1): 28-32.

[Abstract](98)

Abstract:
The existing data mining methods are mostly focused on relational databases and structured data, but not on complex structured data (like in extensible markup language(XML)). By converting XML document type description to the relational semantic recording XML data relations, and using an XML data mining language, the XML data mining system presents a strategy to mine information on XML.

Construction of Mediators for Heterogeneous Data Source Integration Systems

GAO Ming, SONG Han-tao

2003, 12(1): 33-36.

[Abstract](186)

Abstract:
To construct mediators for data integration systems that integrate structured and semi-structured data, and to facilitate the reformulation and decomposition of the query, the presented system uses the XML processing language (XPL) for the mediator. With XPL, it is easy to construct mediators for data integration based on XML, and it can accelerate the work in the mediator.

Concurrent Constraint Programming:A Language and Its Execution Model

LIAO Le-jian, CAO Yuan-da

2003, 12(1): 37-41.

[Abstract](96)

Abstract:
To overcome inefficiency in traditional logic programming, a declarative programming language COPS is designed based on the notion of concurrent constraint programming (CCP). The improvement is achieved by the adoption of constraint-based heuristic strategy and the introduction of deterministic components in the framework of CCP. Syntax specification and an operational semantic description are presented.

License Plate Recognition Based on Transform Coding and Neural Network

LI Xiao-ping, HU Hai-sheng, SONG Han-tao, ZHU Jian-xue, DING Yan

2003, 12(1): 42-45.

[Abstract](183)

Abstract:
A method of vehicle license plate recognition utilizing Karhunen-Loeve(K-L) transform is provided. The transform is used to extract features from a mass of image templates, to describe high-dimensional images with low-dimensional ones, and moreover, to implement data compression and play down complexity of the neural network. With the character to reduce eigenspace dimensionality of K-L transform and the ability to map data of BP network, the method does effectively in recognizing license plates.

DSR-Based Selective Repeat ARQ Protocol in MANET

ZHANG Quan-xin, SONG Han-tao

2003, 12(1): 46-49.

[Abstract](117)

Abstract:
The efficient route algorithms involved in mobile ad hoc network(MANET) are studied. An arrangement of a combination of the traditional dynamic source routing(DSR) protocol is put forward and the selective repeat ARQ protocol is put forward by analyzing and studying them in detail and providing the scheme. In networks, especially in wireless networks, the nodes are capable to process data much faster than transmission, the DSR-based selective repeat ARQ protocol has real meanings in MANET.

Numerical Simulation of the Protective Effect of Complex Boundaries Toward Shock Waves in a 3D Explosive Field

WU Kai-teng, NING Jian-guo

2003, 12(1): 50-54.

[Abstract](160)

Abstract:
A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.

Self-Adaptive Matching Method of Signal and Energy Transmission

LI Jie, QU Xiu-jie, LI Zhe, ZHANG Feng

2003, 12(1): 55-58.

[Abstract](177)

Abstract:
Aimed at the rapid message setting of the passive systems, the efficiency of energy transmission and the characteristics of signal transmission in the message setting are analyzed, which is based on the methods of the circuit analysis and the electromagnetic induction technology. A self-adaptive impedance matching method of signal and energy transmission, which can set the message rapidly and effectively, is put forward. The electromagnetic induct setting system will reach the highest energy transmission efficiency when the equivalent resistance of the second loop is equal to the resistance of the first loop. The greater the ratio of the equivalent resistances is, the higher efficient the signal transmission has. Moreover, the validity of the method is verified by circuit design and tests.

Optimum Optical Length of the Gas Cell Used for Monitoring Gas-In-Oil with FTIR

LIU Xian-yong, HUANG Feng-lei, WANG Xia, ZHOU Fang-jie

2003, 12(1): 59-63.

[Abstract](79) [PDF 181KB](2)

Abstract:
Dedicated experiments are designed to collect the infrared spectra of dissolved gas-in-oil of power transformers. Spectra of diagnostic gases are collected by 3 different laboratorial FTIR spectrometers using 3 different gas cells with various sets of equipment parameters. A formula is deduced to calculate the shortest optical length to detect a specific concentration according to measurements on gases with known concentrations near to the minimum detection limit. Collected spectra and calculated results suggested that the optimum optical length of the gas cell should be 150 mm to realize on-line monitoring of diagnostic gases within the required concentration range. At the end, an economic novel design of the gas cell is proposed based on the optimum length.

Intelligent Information Processing in Imaging Fuzes

WANG Ke-yong, ZHENG Lian, SONG Cheng-tian

2003, 12(1): 64-67.

[Abstract](170)

Abstract:
In order to study the problem of intelligent information processing in new types of imaging fuze, the method of extracting the invariance features of target images is adopted, and radial basis function neural network is used to recognize targets. Owing to its ability of parallel processing, its robustness and generalization, the method can realize the recognition of the conditions of missile-target encounters, and meet the requirements of real-time recognition in the imaging fuze. It is shown that based on artificial neural network target recognition and burst point control are feasible.

Experimental Study on Electrorheological Performance of a Composite Material

CHEN Shu-mei, WEI Chen-guan

2003, 12(1): 68-71.

[Abstract](185)

Abstract:
By using SrTiO 3/PANI as a dispersed phase and silicone oil as a dispersion medium, the rheological characteristic of the dispersion medium under an electric field and the ERF performances of the mixture of SrTiO 3/PANI composite particles and silicone oil under different dispersed phase consistencies and different medium viscosities have been investigated. The measurements of the rheological characteristic, that is the shear stress of ERF, under shearing flow were performed with a Couette-type rheometer manufactured by HAAKE. It is proved that the rheological characteristic of the dispersion medium follows Newtonian fluid viscosity law and the ERF rheological characteristic of the mixture of the dispersion medium and dispersed phase obeys Bingham fluid model under electric field. The experimental result shows that the effects of different phase consistencies and different dispersion medium viscosities on ERF performances are great. The testing expressions of shear stress vs. electric field under different conditions have been obtained by polynomial fit, which is the theory foundation of application in engineering.

Product Maintenance Oriented Remote Monitoring and Diagnosis System

ZHANG Zhi-jing, LIN Fei

2003, 12(1): 72-75.

[Abstract](123)

Abstract:
A research on maintenance oriented remote monitoring and diagnosis modular as well as the data transportation technique is carried out. An opened and modularized data share framework integrated with virtual graphic transportation is presented to realize the data exchange. As a result, it implements a real-time monitoring, diagnosis and maintenance system based on WWW. An effective support technique for the real-time remote fault diagnosis, maintenance and entire life cycle design of products is supplied.

Application of Genetic Algorithm in the Layout of Fixture Components

JIAO Li, SUN Hou-fang

2003, 12(1): 76-79.

[Abstract](231)

Abstract:
Automation in the layout of fixture components is important to achieve efficiency and flexibility in computer aided fixture design. Based on basic genetic algorithm and particulars of different fixture components, a method of layout space division is presented. Such techniques as suitable crossover rate, mutation rate and selection arithmetic element are adopted in the genetic operation. The results show that genetic algorithm can effectively be applied in the automatic layout of fixture components.

Dynamic Characteristics of Complex Structure Under and Out of Water

FENG Hui-hua, LIAO Ri-dong, ZUO Zheng-xing, RONG Ke-lin

2003, 12(1): 80-84.

[Abstract](217)

Abstract:
To understand the dynamic characteristics of the whole period of a complex structure's launching out of water, on the basis of FEM formulations deduced for solving coupled fluid-structure problems with strong-coupled method, FE models used to simulate the structure surrounded with fluid domains are established. The modal experiment on the real structure under shallow water shows great accordance with simulating results. Based on this verification, dynamic character parameters of all FE models simulating each phase of the structure's launching out of water are abstracted with unsymmetric algorithm, which can comprehensively describe the dynamic characters of the structure in its whole working process. Conclusions drawned from these calculations are successfully applied in works of evaluating the structure's performances and reliabilities.

Pretreatment of Corn Stalk by Steam Explosion

SHAO Zi-qiang, TIAN Yong-sheng, TAN Hui-min

2003, 12(1): 85-88.

[Abstract](93)

Abstract:
A steam explosion pretreatment, which is one of the best ways of pretreating plant stalk, is applied at various severities to corn stalk. It could effectively modify the super-molecular structure of corn stalk and defibrating corn stalk into individual components. The relationship between yield of reducing sugar and the operating conditions, including temperature, pressure of steam explosion pretreatment and acidity, is also established. Experimental results prove that the steam explosion substantially increases the yield of reducing sugar, and the optimal condition for steam explosion is as follows: the pressure is 2.0 MPa, the pressure-retaining time 300 s, the initial acid concentration 1% and the acid treatment time 24 h.

Bondage and Reinforcement Number of γ_ffor Complete Multipartite Graph

CHEN Xue-gang, SUN Liang, MA De-xiang

2003, 12(1): 89-91.

[Abstract](244)

Abstract:
The bondage number of γ f, b f(G) , is defined to be the minimum cardinality of a set of edges whose removal from G results in a graph G′ satisfying γ f(G′)> γ f(G) . The reinforcement number of γ f, r f(G) , is defined to be the minimum cardinality of a set of edges which when added to G results in a graph G′ satisfying γ f(G′)< γ f(G) . G.S.Domke and R.C.Laskar initiated the study of them and gave exact values of b f(G) and r f(G) for some classes of graphs. Exact values of b f(G) and r f(G) for complete multipartite graphs are given and some results are extended.

Existence of Positive Periodic Solutions for Two Species Population Growth Model

REN Jing-li, GE Wei-gao

2003, 12(1): 92-96.

[Abstract](153)

Abstract:
Existence and nonexistence criteria are established for the positive periodic solutions of two species population growth with periodic delay by applying continuation theorem of coincidence degree theory.

Existence of Two Solutions of Nonlinear m-Point Boundary Value Problems

REN Jing-li, GE Wei-gao

2003, 12(1): 97-100.

[Abstract](161)

Abstract:
Sufficient conditions for the existence of at least two positive solutions of a nonlinear m -points boundary value problems are established. The results are obtained by using a new fixed point theorem in cones. An example is provided to illustrate the theory.

Monotonic Property in Field Algebra of G-Spin Model

JIANG Li-ning

2003, 12(1): 101-104.

[Abstract](186)

Abstract:
Let F be the field algebra of G -spin model, D(G) the double algebra of a finite group G and D(H) the sub-Hopf algerba of D(G) determined by the subgroup H of G . The paper builds a correspondence between D(H) and the D(H) -invariant sub- C * -algebra A H in F, and proves that the correspondence is strictly monotonic.

One-End Data Method for Fault Position Estimate of Two-Parallel Transmission Lines

ZHANG Qing-chao, LIU Fei, WU Yong-feng, SONG Wen-nan

2003, 12(1): 105-108.

[Abstract](67)

Abstract:
An accurate numerical algorithm for three-line fault involving different phases from each of two-parallel lines is presented. It is based on one-terminal voltage and current data. The loop and nodel equations comparing faulted phase to non-faulted phase of two-parallel lines are introduced in the fault location estimation modal, in which the faulted impedance of remote end is not involved. The effect of load flow and fault resistance on the accuracy of fault location are effectively eliminated, therefore an accurate algorithm of locating fault is derived. The algorithm is demonstrated by digital computer simulations and the results show that errors in locating fault are less than 1%.

Fast Echo Canceller in IP Telephony Gateway

HUANG Yong-feng, LI Xing

2003, 12(1): 109-112.

[Abstract](85)

Abstract:
The length of the echo path in the IP telephony system is very long. Generally, the echo canceller is implemented on the IP telephony gateway which needs to perform concurrently multi-channel echo cancellation and voice compression. Hence, the most key technique to design the echo canceller is to reduce greatly the computational requirement. For this reason a number of innovative features to implement a fast echo canceller are presented. The key components of this canceller include: the separation of adaptive and cancel filters, non-real-time adaptation and real-time cancellation, sharing VAD algorithms with the speech codec, the incorporation of delay indexing with zero coefficients, and windowing the adaptive filter coefficients to reduce the cost of DSP during the cancellation. Finally, the performance of the echo canceller is summarized; the results of evaluation show that the performance gains for echo cancellation are significant.

2003 Vol. 12, No. 1