Table of Content

31 March 2002, Volume 20 Issue 1

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Articles

An Experimental Study on the Factors Influencing Ebullient Tests of Highly-wetting Liquids

HOU Ding-wei, MA Chong-fang, LIU Deng-ying

2002, 20(1):  1-5. 

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An experimental and mechanismic study was conducted to investigate the factors effecting boiling tests of highly-wetting liquids. The results showed that only the experimental data obtained through a rigorous test procedure could be compared with each other.

A Fine Needle Probe for Determining the Thermal Conductivity of Penetrable Materials

XIE Hua-qing, WANG Jin-chang, CHENG Shu-xia, LIU Yan

2002, 20(1):  6-9. 

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A fine needle probe for determining the thermal conductivity of penetrable materials such as fluids, fruit, animal fresh has been developed. The present probe is constructed by inserting twenty strands of copper wire with electrical insulation coating into a fine stainless steel needle. The copper wire serves both as a heating unit and as an electrical resistance thermometer. The effects on the thermal conductivity measurement caused by the thin needle wall has been analyzed. It is found that the effects can be negligibly small if the instruments and the measurement procedure is adequately designed. The usability of the as-constructed apparatus for the penetrable materials has been tested to measure the thermal conductivity of liquid, fruit and animal fresh. The accuracy of the measurement was estimated to be ±3%.

A Research on the Framework of Organization of Brazed Mono-layer Diamond Grinding Wheel with Ni-Cr Alloy

WU Zhi-bin, XU Hong-jun, YAO-Zheng-jun, XIAO Bing, FU Yu-can

2002, 20(1):  10-13. 

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We have successfully developed a brazed mono-layer diamond grinding wheel with Ni-Cr alloy under Ar atmosphere. SEM-EDS microanalyses have shown that during brazing the chromium present in the alloy segregated preferentially to the surface of the diamond to form a chromium-rich reaction product. X-ray diffraction revealed that the wetting and bonding behavior on the diamond surface by Ni-Cr alloy melt is realized through Cr₇C₃ which is produced by interaction between Cr atoms of Ni-Cr alloy and C atoms of the diamond surface at elevated temperatures.The analyses also revealed that the bond between the alloy and the steel substrate was established through a cross-diffusion of iron and chromium and the formation of (Fe_x Cr_y) C-type carbides.Finally a grinding test show ed that the wear modes of such a brazed grinding wheel were mainly grit fracture and attrition rather than grit dislodgment from the bond.

A Research on the Characteristics of Attenuating Vibration of a Multi-medium Coupling Shock Absorber for Precision Equipment

YANG Ping

2002, 20(1):  14-20. 

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A multi-medium coupling shock absorber is designed by ingeniously coupling the air, oil, rubber and metallic elastic component to meet the requirement of resisting violent impact and attenuating vibration in the vibration-impact-safety device of electronic-information equipment. The model machine shows strong nonlinear dynamic characteristics in the multi-parameter coupling dynamic test. Based on this, the nonlinear dynamic characteristics model is established by combining the theoretical analysis and the actual structural parameters applied in modeling. The analytic result shows that the multi-medium coupling shock absorber has a good dynamic performance and controllable design-capability. The modeling method is applicable to the research and design of other shock absorbers

Characteristics Analysis of Noise Transfer of Wavelength Converters Based on Cross-gain Modulation

WU Shi-bao, YAN Sen-lin, LIU Xiao-fei, SUN Xiao-han, ZHANG Ming-de

2002, 20(1):  21-24. 

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A theoretical model describing the noise conversion characteristics of wavelength converters based on XGM in SOA is established in this paper. The numerical simulation results show that the input pump power and probe power have direct influences on the noise conversion. In an appropriate range of input power, the noise can be effectively suppressed and the quality of the converted signal is improved.

Intra band Crosstalk in an OXC Based on Demultiplexers Using FBG

HE Jin-lin, SUN Xiao-han, ZHANG Ming-de, DING Dong

2002, 20(1):  25-29. 

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Basing on the reflection spectrum of a FBG filter, the impacts of intraband coherent crosstalk and intraband incoherent crosstalk in an OXC based on demultiplexers using fiber Bragg grating (FBG) filters, deduces the system power penalty and discusses in detail the dependence of system degradation on the coupling coefficient, grating length and polarization matching factor, etc.

The Implementation of Q Factor On-line Detection Based on DSP Technology in Optical Fiber LANs

LI Jin-hui, SUN Xiao-han, ZHANG Ming-de, DING dong

2002, 20(1):  30-34. 

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In view of the characteristics of PHY(physical layer) in optical LAN(local area network), an on-line method for Q factor detection based on DSP(digital signal processor) technology is put forward and its mathematical physical model is discussed. A series of simulative tests indicate that the method is valid, feasible, and convenient.

A Projective Method for Solving the Boundary Value Problems of the Electromagnetic Field in Special Domains

SUN Lian-you, HONG Wei

2002, 20(1):  35-37. 

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An algorithm is presented for solving electromagnetic problems in special domains with many branches. According to the geometric shape of domains the large matrix is divided into several small ones. The convergence rate of iterative solution is geometrical. The method is applied to the reflecting parameter and phase analysis of the slotting slow wave guide. Then we find the main factors of affecting the above parameter and phase, finally give them the relation curves.

An Analysis of the Inter leavers for Turbo Codes

ZHAO Guang-ling, WU Le-nan

2002, 20(1):  38-41. 

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Several interleavers are applied to Turbo codes and simulated respectively. The performances are compared with each other. A new interleaving scheme is put forward by this paper that combines two different types of interleaver into a new interleaver. Since there is a strong correlation in time between information bits and check bits produced by the first constituent encoder not being interleavered, an additional symbol interleaver is added to the multiplexer to reduce the bit error rate ulteriorly in the flat Rayleigh fading channel.

A New Algorithm for Displacement Field Estimate Based on Joint Luminance and Motion Segmentation

TANG Li, ZHANG Zhao-Yang

2002, 20(1):  42-46. 

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Motion estimate is a key technology in computer vision and video signal processing. It is widely used in international standards for video communication. Due to the difference between real motion and apparent motion and the existence of the aperture and the occlusion problem, it seems difficult to obtain the precise motion field. In this paper, we present a displacement field estimate algorithm based on joint luminance and motion segmentation to obtain a satisfactory result.

Low-complexity Blind Multiuser Detection of CDMA Signals in Fading Channels

LIN Zhi-qiang, YOU Xiao-hu, WANG Yong

2002, 20(1):  47-50. 

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The problem of blind multiuser detection of CDMA signals in fading channels is considered. It is noted that the minimum-mean-square-error (MMSE) detector often loses phase to lock a desired signal when the desired signal dips into a deep fade. This paper proposes a suboptimal blind MMSE detector that is incorporated into the desired user's signature waveform and the auxiliary vector to achieve low-complexity. It decouples the signal phase, and fits into realistic fading channels.

Simultaneous Extrapolation of Electromagnetic Scattering of Multi-wires in Time and Frequency Domains Based on Hermite Expansion

TONG Chuang-ming, HONG Wei, ZHOU Hou-xing

2002, 20(1):  51-54. 

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The entirety responses of the induced currents on the wires in both time and frequency domains can be obtained at the same time by simultaneous extrapolation computation using both the early-time response and the low-frequency information of the induced currents. The time-domain response of the induced currents on a scattering object irradiated by a plane wave with a Gaussian pulse in time is expanded as an associate Hermite series. Using the isomorphism of the associate Hermite function and its Fourier transform, the frequency-domain information can also be obtained. According to the corresponding relation between time-domain analysis and frequency-domain analysis, and using the early-time response and the low-frequency information of the induced currents, the non known coefficients in the expansion series can be determined. Electromagnetic scattering of multi-wires are calculated and analyzed based on this extrapolation method recommended in this paper.

A Study and Discussion on a Controller for Radial Four-degree Freedom Active Magnetic Bearing

ZHU Huang-qiu, XU Long-xiang

2002, 20(1):  55-60. 

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This paper, basing on the state equation of a radial four degree freedom magnetic bearing, presents the steps in using the linear quadratic method of the optimal control theory to design a centralized and decentralized parameters control system. Matlab language is also used to carry out simulation comparison, which proves that the difference is small. In this paper, the structure of hardware and software based on the digital signal processor, the method of debugging and the experimentation result are presented in brief. The vibration amplitude of rotor is about 20μm when the speed of rotor runs between 0 to 60000r/min. The experiment shows that the decentralized controller based on the linear quadratic method meets the demands of active magnetic bearing system. This method may be used for reference in the study and designing of controllers for active magnetic bearing.

Computer Simulation of the Production System of Factory Agriculture

GU Ji-nan

2002, 20(1):  61-65. 

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This is the first time a research that includes the growth of plants, environmental control and economic analysis of the production system of factory agriculture in a single large scale system has been carried out. We build three separate sub-models of the velocity of photosynthetic, environmental control and cost control. Next we construct a comprehensive dynamic model on the basis of three sub-models and the relations between them, and carries out simulation research in this way we obtain the optimum mode of comprehensive environmental control to simultaneously meets the two requirements of better control and lower cost under different external weather conditions.

Indirect Adaptive Decentralized Neurcontrol for a Kind of Nonlinear Large Scale System

HU Shou-song, ZHANG Rui

2002, 20(1):  66-69. 

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An indirect adaptive decentralized neurcontrol is proposed for a kind of nonlinear large scale systems by adopting a decentralized control mode. Fuzzy neural network is used to identify the subsystem for building NARMA model and adjusting the parameter of the controller. Besides, the adaptive control and sliding-model-control method is used to extinguish nonlinear interconnection between each subsystems and disturbances with unknown bounds. The indirect adaptive decentralized neurcontrol controller is verified by its application to a double inverted pendulum system, the results of simulation confirm the effectiveness of the proposed algorithm.

An Algorithm of Make span Scheduling for Hybrid Production in Dynamic Environment

XU Zhi, XI Yu-geng, HAN Bing

2002, 20(1):  70-76. 

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To solve the problem of the optimal production time scheduling for a class of hybrid production process in dynamic environment, we use the rolling optimization method in accordance with the basic principle of predictive control and put forward the concept of available operation set. The scheduling problem in dynamic environment is reasonably divided and the sub-questions are standardized. An optimized algorithm based on MILP is given for low dimension and a heuristic algorithm for high dimension is proposed. The emulation of an actual example indicates that the algorithm is practicable.

The Confidence Intervals of the Nonparametric Regression Function

XUE Liu-gen

2002, 20(1):  77-79. 

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In the paper, we apply random weighting methods to construct random weighting statistic for the unknown regression function m(x) and prove that the random weighting approximation can attain the accuracy of o(n^-1/(d+2) lnnM_n),where 0< M_n→∞. The confidence intervals of m(x) can be constructed by this result.

Ecological Optimal Performance of a Ferroelectric Ericsson Refrigerator

YANG Hui-shan

2002, 20(1):  80-83. 

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By utilizing the finite time thermodynamics and the thermodynamic properties of a ferroelectric, the ecological optimal performance of a class of ferroelectric Ericsson refrigerators with thermal resistance and nonperfect regeneration is studied. Some new performance parameters are obtained. The conclusions obtained here may provide some new theoretical guidance for the development and optimal design of ferroelectric Ericsson refrigerators.

A Generalized Post-processing Algorithm to Compensate Geometric Errors of Multi-axis NC Machine Tools with Arbitrary Configuration

HE Yao-xiong, ZHOU Yun-fei, ZHOU Ji

2002, 20(1):  84-89. 

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The multi-axis NC machine tool typically consists of two open kinematics chains:workpiece chain and cutter chain. According to this principle, the kinematics model and error model of multi-axis NC machine tools have been analyzed and set up, and then a generalized algorithm for post-processing of multi-axis NC machine tools is presented in this paper. The algorithm can be used to generate the coordinated motion value for all types of multi-axis NC machine with all sorts of errors according to the tool-path generated by the CAM system.

Optimal Disposition of Actuators in Intelligent Frame Structures Based on Genetic Algorithm

ZHOU Xing-de, WANG Feng-quan

2002, 20(1):  90-93. 

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This paper is based on the modal degree of controllability and the least cost function with a view to overcoming the difficulties faced arising out of the application of combined optimization to disposition actuators. In the paper, the genetic algorithm is used to solve the optimal disposition in active vibration control. The introduction of constraint condition in to conventional genetic algorithm is improved to fit into the solution of frame structures. Finally, a numerical example is presented to show the effectiveness of the method.

A Study on the Uncertainty lnference in Fuzzy Rule

XIAO Wei-yue

2002, 20(1):  94-98. 

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In this paper, the uncertainty problems with regard to fuzzy truth value in fuzzy rules are investigated in depth. First, the different meaning of six propositions is completely analyzed. Next, a new logic combination relation, the generalized logic relation, is proposed in accordance with actual conditions of fuzzy rule application. Finally, the fuzzy sets matching degree and the fuzzy rule matching degree are defined and the inference algorithm of condition truth value and result truth value is presented, and the generalized uncertainty inference model is formed.

A New Technology Based on RBFNN and GA for Resolving Overlapped Peaks

LI Yi-bo, HUANG Xiao-yuan

2002, 20(1):  99-103. 

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Radial basis function neural network (RBFNN) based on chromatographic peakshape functions and spectral lineshape functions has been constructed. A genetic algorithm based on feasible field constraint and shared niche technique is introduced to enable this RBFNN to acquire the ability of reconstruction. Next the RBFNN was introduced into the resolution of overlapped peaks of spectrum. This paper tries to build up a integrative frame suited to the resolution of spectrum and chromatogram, and partial results have been obtained.

Phase-locked Loops Used with Atomic Hydrogen Frequency Standard

ZHANG Wei-qun, ZHANG Yi-ping, WANG Guan-zhong, YU Shuang-lin

2002, 20(1):  104-108. 

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Active atomic frequency standards, such as hydrogen maser, are characterized by a very good frequency stability. However, they deliver a signal at a power level and at a frequency that are not practical to the users. This paper descries the techniques used to phase lock to the hydrogen maser a standard crystal oscillator at a cardinal frequency.

Research Notes

Accurate Measurement of the Coefficient of Thermal Deformation for Metal

HUANG Qi-sheng, FEI Ye-tai, ZHANG Yong, HU Peng-hao

2002, 20(1):  109-110. 

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This paper analyzes the change of the forced deformation that occurs along with thermal expansion of material at rising temperature. The change of the forced deformation must be taken into account in the accurate measurement of thermal deformation of metal. The concepts of the thermal deformation coefficient and the relation between the coefficient of thermal deformation and that of thermal expansion are discussed.