Table of Content

30 June 1997, Volume 15 Issue 2

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Articles

ELECTROMACNETIC SURFACE TM WAVES ON THE SUPERLATTICE

WANG QI, JIN ZHE

1997, 15(2):  127-135. 

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The propagation characteristics of surface electromagnetic TM waves on the superlattice are presensed in this paper. The analysis shows that the orientation angle θ of the crystal axis of the liquid crystal in superlattice plays an important role in the wave propagation. The dispersion relation, the distributions of the electric and magnetic fields of the waves are given respectively. The necessary conditions for the surface wave existence are:(1) θ=0 or θ=π/2, (2) The real part of the complex dielectric constant of the cladding material has minus value.

EFFECTS OF DIFFRACTION ANGLE TRUNCATION ON THE RESULTS OF RIETVELD ANALYSIS

LIU HONGCHAO, KUO CHANGLIN

1997, 15(2):  136-142. 

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Rietveld method is an efficient way to find out the crystal structure and micro-structure of solids. Data treatment strategy has great effect on the its results. In this paper, the effects of truncating angle on its results were sindied systematically. It was found that the site coordination of heavy atoms can be obtained at medium diffraction angle while it needs more high angle data in order to determine the cell parameters and site coordination of light atoms. With the increase of data at high diffraction angular range, the profile parameters almost keep constants; the changes of numerical criteria of fit(including D-wd) are etermined by background parameters.

THE ELEMENTS OF OXIDE CONDITION WHICH INFLUENCE THE ELECTRET PROPERTIES OF THE THERMALLY WET-GROWN SiO₂ FILMS

LIN HUAMAO, XIA ZHONGFU, SHEN SHAOQUN

1997, 15(2):  143-148. 

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The structures of the SiO₂ films and the distribution of the energy levels in the SiO₂ films, which influences the stability of the space charges stored in the samples, are directly determined by the oxide condition. In this paper, the samples are produced by several oxide conditions. The stability of the space charges stored In the SiO₂ films are investigated by using surface potential decay measurement.The activation energies of detrapping charges in the samples are estimated by using Thermally Stimulated Discharge (TSD) method. And the density of the sodium ions in the samples are determined by Capacitance-Voltage (C-V) Analyses technique. Based on these results, the inherent relationship between the stability of the space charges and the oxide condition is analyzed.

THREE-DIMENSION COMPLEX RAY EXPANSION OF LOCAL VECTOR PLANE WAVE

DENG SHUHUI, RUAN YINGZHENG, FENG LIN

1997, 15(2):  149-156. 

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The paper presents not only the ontire formula of the three-dimension complex ray expansion of the local vector plane wave with parallel beams, but also the formulas of the expansion truncation error and the discretized expansion error. The three-dimonsion complex source expansion parameter of the local vector plane wave, including complex source point parameter, expansion interval,and the expansion radius can ho determined if the expansion error and the maximum expansion interval is given previously. Thus the error requirement can be met by the synthesized field everywhere in space, which is from expansion place to the maximum expansion interval in the area of the required radius. This method is especially suitable for the analysis of wave propagation and target scattereing characteristics.

PROCESSING OF ELECTROMAGNETIC PULSE DATA BY DYADIC WAVELET TRANSFORM

SONG YUMING, CHEN BIN, FANG DAGANG

1997, 15(2):  157-162. 

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The difference between the property of singularity of a signal and that of noise under the dyadic wavelet transform is revealed. Due to this merit,the experimental data of the interior electric and magnetic intensity of a concrete building radiated by a electromagnetic pulse are processed by singularity detection and denoising.

EFFECTIVE PERMITTIVITY OF ANISOTROPIC COMPOSITE MATERIAL OF DENSE NON-SPHERICAL PARTICLES AND CONDUCTIVIY TRANSITION

JIN YAQIU, LI GANG, HUANG XINGZHONG

1997, 15(2):  163-168. 

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By using the strong fluctuation theory and introducing an auxiliary permittivity, the effective permittivity can be derived, and is applied to the calculation of effective conductivity of composite material embedded by dense conducting and non-spherical particles. Numerical results for the functional dependence on fractional volume, correlation length, and frequency are presented.It can be seen that the composited material embedded by dense conducting and non-spherical particles has anisotropic effective conductivity and different conductivity transfer.

STUDY OF ADAPTIVE EQUALIZER FOR GSM DIGITAL MOBILE RADIO

GUO JINGHONG, CHENG SHIXIN

1997, 15(2):  169-173. 

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the CEPT/GSM digital mobile radio system is based on TDMA access structure with a bit rate of 270.833kbit/s and a GMSK modulation. This paper studios the implements and performances of modified viterbi adaptive equalizer based on MLSE for GSM system.

DEVELOPMENT OF AN EXPERIMENTAL SET-UP FOR SIMULTANEOUSLY MEASURING THERMALLY STIMULATED CURRENT AND LUMINESCENCE

XIONG YANLING, WAN XUAN, LIN JIAQI, LEI QINGQUAN, XU CHUANXIANG

1997, 15(2):  174-178. 

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In this paper, we have introduced an experimental set-up for simultaneously measuring thermally stimulated current and thermally stimulated luminescence used in studying the carrier trap structure of polymers, including the project of sample cell, especially, the development of single photoncounter for detecting the thermally stimulated luminescence.

RESEARCH AND DISCUSSION ON THE CONTROL SYSTEM OF ACTIVE MAGNETIC BEARINGS

QI QINGZHONG, ZHAO HONGBIN

1997, 15(2):  179-186. 

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The technology of Active Magnetic Bearing (AMB) is now spreading throughout the world. Here the rotor-AMB system is studied in several different respects. We set up a more accurate model for the control object, study three kinds of controllers, and respectively compare their specifications such as system stability margin, dynamic performance and steady-state accuracy. This paper also presents the negative influence of phase-lag network which is widely used in AMB linear controller. The detailed analyses in this paper will make it a good reference to the designing Of the AMB control system.

THE EXPERIMENTAL STUDY OF M/A-SI:H SCHOTTKEY BARRIER PARAMETERS

ZHANG ZHIGUO, SU CHANGHOU

1997, 15(2):  187-192. 

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An experiment technique is introduced to modulate the neutral bulk region of M/a-Si:H system with light, and to measure the barrier characteristics of M/a-Si:H junction with high frequency C-V meter. The results obtained and available data from literatures arc compared. With much emphasis, the unusual phenomenon in Al/a-Si:H structure is described.

RESEARCH ON SOLVING STRATEGY BASED ON MULTIEXPERT OPTINIZING

ZHENG DELING, JI BINGXI

1997, 15(2):  193-197. 

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The strategy of solving problems in carburizing expert system is studied in this paper. In order to advoid subjective view and one-sidedness,multiblackboard strategy of solving problems is proposed, which are problem blackboard, domain blackboard, argument blackboard and conclusion blackboard.The problems of no generally-acknowledge are multiple experts.Tnis paper builds a theoretical framework of argument on the basis of propositional knowledge,and the argument algorithms is designed. The results of the experiment are satisfactory.

SIMULATION RESEARCH OF 3D DEFECT RESPONSE FOR REMOTE FIELD EDDY CURRENT NONDESTRUCTIVE TEST

ZHAO YANG, CHEN MEIJUAN, QU MINGXING

1997, 15(2):  198-204. 

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The remote field eddy current (RFEC) technique is a new type of inspection technique for pipelines inspection which is not influenced by skin effect. However, up to date, the physics research of RFEC has not been finished thoroughly and some phenomena are still unsolved and unexplained. In this paper the A,V-A_s-ψ model and substructure-front technique are presented in FEM,and the simulating method on microcomputer ic also given for 3D RFEC defect response analysis. The obtained results show that,since the change of eddy current distribution surrounding the circumferential defect is more stronger than that of axial defect, the signal of circumferential defect response is therefore stronger than that of axial defect.

STUDY ON THE FLOW BEHAVIOR OF STEAM PROPAGATION THROUGH POROUS MEDIA WITH NON-UNIFORM POROSITY

HU YAOJIANG, SHI MENGHENG

1997, 15(2):  205-210. 

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The mass and energy conservation equations in vapor-liquid two-phase zone are solved for the case of steam injecting into a liquid-saturated porous media with non-uniform porosity. The variation of phase interface position with time is obtained. The influences of porosity distribution and averaged saturation in the two-phase zone on the steam flow behavior are also discussed. By comparing the theoretical results with the experimental data, it is found that the model presented in this paper can be used accurately for steam passing through a non-uniform porous media with more than 0.3mm averaged particle diameters.

AN ARTIFICIAL NEURAL NETWORK MODEL ON CORRELATION BETWEEN THE HETEROGENEOUS IGNITION TEMPERATURES OF COAL CHAR PARTICLES AND COALS

QIAN SHIZHI, LU JIDONG, LI GUANG

1997, 15(2):  211-216. 

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Taking advantage of the nonlinear dynamics characteristics and self-learning characteristics f artificial neural network, an artificial neural network model on correlation betaween the heterogeneous ignition temperatures of coal char particles and coals is presented and verified in this paper. The results show that the model can predict heterogeneous ignition temperatures of coal char particles bassed on the values of coal proximate analysis accurately.

SELF-ORGANIZATION NEURAL TREE APPLIED TO STRUCTURE-ACTIVITY RELATIONSHIP OF FENTANYL DERIVATIVES

LU WENCONG, FANG JIANHUI, DING YIMING, YAN LICHENG, CHEN NIANYI

1997, 15(2):  217-222. 

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In this paper, the non-linear relationship between the characteristic parameters and analgesic activities of a series of fentanyl derivatives is calculated by self-organization neural tree model. The results show that the performance of the self-organization neural tree is good and the successful claasification rate is rather nigh. Therefore, the model might be used ac an effective assistant technique for the investigation of structure-activity relationship of drugs.

THE MAXIMUM REFRIGERATION RATE OF AN IRREVERSIBLE QUANTUM STIRLING REFRIGERATOR

WU FENG, SUN FENGRUI, CHEN LINGEN

1997, 15(2):  223-228. 

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In this paper, the effect of thermal resistance, heat leak and finite rate processes on the optimal performance of a irreversible quantum stirling refriger at or is studied. The maximum refrigeration rate and the optimal relation between the rate of refrigeration and the performance coefficient is derived. The results provides some theoretical guidance to the optimum design of a quantum refrigerator.

ACCELERATION AND STABLIZATION MECHANISM OF ELECTROLESS NICKEL DEPOSITION BY THIOUREA

HAN KEPING, FANG JINGLI

1997, 15(2):  229-233. 

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Influences of thiourea on electroless nickel deposition rate, hydrogen evolution, polarization curves and stationary potential wore determined. Together with the X-ray photoelectron spectroscopy (XPS) analysis of the deposit. the mechanism for acceleration and stabilization of electroless nickel deposition by thio-urea has been discussed.

MANUFACTURE AND EXPERIMENTAL RESEARCH OF A MINIATURE PULSE TUBE REFRIGERATOR

XU MINGYAO, HE YALING, CHEN ZHONGQI, ZHANG LI, ZHAO JIAWEI

1997, 15(2):  234-236. 

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A miniature pulse tube refrigerator which has a special structure is suggested in this paper. Experimental research of the suggested refrigerator is also carried out. The lowest refrigerating temperature is achieved 159.4K at 1.19 MPa and 11Hz.

THE RESEARCH ON IMPROVING REGENERATION ABILITY OF THE DIESEL ENGING EXHAUST PARTICULATE FILTER BY INFRARED RADIATION

WEI YUANWEN

1997, 15(2):  237-241. 

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The author puts forward a new conceptionic improve regeneration ability of the honeycomb ceramic filter for diesel engine exhaust particulate by infrared radiation. Heating principle of infrared radiation and heating character of infrared radiating material are discussed. The three regeneration plans with or without infrared radiating material coating have been experimented. The experimental results indicate that the new concoption is feasible.

HYDROTHERMAL SYNTHESIS OF ACICULAR α-Fe₂O₃ AND ITS CHARACTERIZATION

WEI YU, ZHENG XIEZHONG, SHAO SHUXIA, LU PING

1997, 15(2):  242-248. 

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Acicular α-Fe₂O₃ particles hydrothermally synthesized at 180℃ from Fe(OH) ₃ gel in the presence of morphological modifiers are characterized by transmission electron microscopy, X-ray diffraction, infrared spectroscopy and thermal gravimetric analysis. The influence of 4 modifiers on the formation of acicular α-Fe₂O₃ is compared by aging reaction at 100℃. The presence of HEDP and DMPG results in acicular and spindle crystals elongated along the c axis, tartaric acid and citric acid gave rod-like and short-column crystals. The choice of optimum reaction temperature depends on the modifier and its concentration.

THE PREPARATION OF CaTiO₃ WITH HOLLOW SPHERICAL FORM BY SPRAY PYROLYSIS TECHNIQUE

FU XIXIAN, SHAN ZHIXING, ZENG SHULAN

1997, 15(2):  249-252. 

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The CaTiO₃ powder synthesized by spray pyrolysis method is hollow spherical form and pure with high specific surface. Absorbing enough energy it has manifested some photocatalytic ability.