Table of Content

25 October 2007, Volume 35 Issue 10

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Electronics, Communication & Automation Technology

Fundamentals and Practice of Clean Bleaching Technology for Medium-Consistency Pulp

Chen Ke-fu Li Jun

2007, 35(10):  1-6. 

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Due to its high risks in environmental pollution , great consumption of water and energy , and its limitedyields , the traditional bleaching technology (CEH) for low-consistency pulp by chloric agent is bound to be substitutedby such technologies as oxygen delignification , chlorine dioxide bleaching , and hydrogen peroxide bleachingfor medium-consistency pulp , or by the combined methods of these technologies. This paper analyzes the characteristicsof each bleaching technology and investigates the oxygen delignification and hydrogen peroxide bleaching forthe medium-consistency pulps with different stocks. Then , based on the engineering experience , the less-pollutionbleaching technology and the total-chlorine-free bleaching technology suitable for the paper industry in China arepresented , with the aim of meeting the increasingly strict environmental standards and implementing clean bleachingin paper industry.

Mathematical Model for On-Line Measurement of Pulp Kappa Number

Liu Huan-bin Li Ji-geng Yan Dong-bo Shen Wen-hao

2007, 35(10):  7-13. 

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Based on the Kubelka-Munk equation and the spectrum features of the residuallignin in pulp , the theoreticalmodel describing the pulp diffuse reflection is established. According to the intemal relationship between theresiduallignin in pulp and the pulp Kappa number , the model for the on-line measurement of pulp Kappa numberis presented. Then , according to the absorbing spectrum of the residuallignin in pulp , F390 , FS60 and FS40 are usedas independent variables to build a simplified measuring model named "tri-wavelength". The simplified model issimple in structure and clear in physical description , and it can reveal the linear relationship between the Kappanumber and the independent variables. However , the proposed model omits the nonlinear relationship between theKappa number and the reflected spectrum due to the simplification and linearization in the transformation from theoreticalmodel to simplified one. In order to solve this problem , the simplified measuring model of Kappa number iscombined with the adaptive neural-fuzzy inference system (ANFIS) to build a fusion model for the on-line measurementof Kappa number. After the sample training , the proposed fusion model is of good stability and high precislon.

Theory and Key Technology of Powder Forming and Consolidation in Multiple Coupled Fiel

Li Yuan-yuan Li Xiao-qiang

2007, 35(10):  14-19. 

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In order to implement the powder forming and consolidation with high densification , good property , highprecision , short time and low cost , the theOIγand key technology of powder forming and consolidation are presentedwith regard to the coupling of the temperature and stress fields and the coupling of the electromagnetic field , thetemperature field and the stress field. By using the newly-developed device for the direct measurement of dynamiclateral pressure during powder compacting process , the densification mechanism of Fe-based powders in the coupledtemperature and stress fields is obtained. Then , a numerical simulation of powder densification in the coupled temperatureand stress fields is carried out , and the forming and consolidation process of Fe-based powders is determinedand optimized. Furthermore , an apparatus for the forming and consolidation in the coupled electric , magnetic, temperature and stress fields is successfully developed , which is then used to determine the forming and sinteringprocesses of Fe-based and WC-based powders under multi-field coupling , reveal the corresponding mechanism ,and simulate the temperature distribution in the coupled electromagnetic and stress fields.

Design of Power Conditioning System for Fuel Cell Power Plant

Huang Shi-sheng Tang Zhao-yang Wang Zhen-min Chen Yi-ting

2007, 35(10):  20-25,48. 

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The power conditioning system of a fuel cell power plant is very important to the reliability and efficiencyof the power plant system as well as to the quality of the output waveform. In this paper , the optimizedcooperation between the main circuit structure of the power conditioner and the fuel cell parameters is investigatedby simulation and experiment , and the law of designing efficient main circuit for the power conditioning systemis proposed. By investigating the mathematical model of the inverter system , some guidance is provided forthe inverter output waveform control. A digital intelligent control system with good practicability , high performanceand low cost is then designed , in which the output waveform control is emphasized. Moreover , the waveformcontrol scheme based on the sliding-mode control policy is investigated , and is then testified by experiments.It is found that the proposed system satisfies the requirements of the power plant , and possesses good reliability, high output waveform quality and great efficiency.

Level Set Method and Its Applications to Topology Optimization of Compliant Mechanisms

Zhang Xian-min Ouyang Gao-fei

2007, 35(10):  26-36. 

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The level set method has recently been proposed and studied as a novel structural topology optimizationmethod , which is flexible in handling complex topological changes and concise in describing the boundarγshape of the structure. In this paper , first , some numerical issues are discussed , such as the solution of Hamilton-Jacobi equations , the re-initialization of the level set function and the extension of velocity fields. Then ,several robust and effective numerical technologies , which are important to the implementation of the level setmethod , are proposed. For example , the upwind difference scheme is used to solve Hamilton-Jacobi equations ,the signature function is modified to ensure the numerical stability , and the fast scanning method is developed toconstruct extension velocities. Moreover , based on the level set method , a topology optimization model for compliantmechanisms is presented. Finally , the proposed level set method is illustrated by the topology optimizationof a displacement inverter.

Microstructure and Wear Properties of AI-Based Bearing AlIoys Fabricated by Mechanical AIIoying

Zhu Min Zeng Mei-qin Ouyang Liu-zhang Wu Zhi-fang Liu Xin

2007, 35(10):  37-43. 

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AI-Pb and AI-Sn bearing alloys were obtained by sintering the AI-Pb and AI-Sn powder mixtures preparedvia mechanical alloying. According to the microstructures of the alloys characterized by means of XRD , SEMand TEM , the Pb or Sn soft phase in a size of about 100 nm homogeneously disperses in AI matrix of the alloys fabricatedunder appropriate mechanical alloying and sintering conditions. It is indicated by the wear test that the AIbasedbearing alloys containing nano-sized Pb or Sn dispersoids are of excellent wear properties. Moreover , accordingto the coarsening behavior of the nanophase particles , the nano-composite structure possesses good stability andthe growth of the second phase still follows the classical ripening theoηdescribed by LSW equation. As for theeffect of the contamination induced by milling on the microstructure of Al-based bearing alloys , the Al₇ Cu₂ Fe phaseforms owing to the Fe contamination , and the adherence of nano-sized Al₂ O₃  phase to Pb particles occurs due to theoxygen contammatlOn.

Review of High-Speed & Precise Progressive Dies of IT Products

Ruan Feng Huang Zhen-yuan Zhou Chi Wang Bo

2007, 35(10):  44-48. 

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This paper investigates both the intelligent design technology and the fracture failure of high -speed & precise progressive dies of IT products. In the investigation , the methods of fuzzy processing , fuzzy clustering and attribute reduction are adopted to make the tacit knowledge of stamping die design explicit , thus achieving the knowledge mining from the design of precise progressive dies. The results of microscopic test show that , in the fracture section , the WC grains are inhomogeneous in size , and the Co content is less than that of the initial carbide material. Analytical results indicate that the fracture failure of the die occurs possibly because the inhomogeneity of WC grains reduces the hardness and wear resistance of the carbide material , and because the Co loss weakens the strength of the material.

Analysis of Rarefied Regions and Rarefied Effects of a Nano-Scale Magnetic Head

Huang Ping

2007, 35(10):  49-53,60. 

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In the present paper, the modified Reynolds equation considering rarefied gas effect is used to calculate the rarefied region of a negative magnetic head working in the distance of 10 nm away. According to the calculated results , discussions and analyses are then presented to reveal the effects of rarefied region and rarefied effect on the working performances of the magnetic head. The results show that (1) the magnetic head works in the slip-flow and transition regions and moves to the transition region with the increase in velocity; (2) the maximum rarefied effect does not occur in the minimum flying height on the rear but at the side edges where the flying height is thinner and the pressure is lower; and (3) if the rarefied effect is considered , the load-carrying capacity of the magnetic head and the maximum pressure decrease , while the minimum pressure slightly changes.

Sound Power Level Measurement for Yangqin , a Chinese Traditional Instrument

Wu Shuo-xian Zhao Yue-zhe Qiu Jian-zhen Wu Li-ling Huang Hong

2007, 35(10):  54-60. 

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Yangqin is one of the most popular Chinese traditional instruments with a long history. Although it is an important regular musical instrument in Chinese music ensemble , its sound power level has not yet been determined. In this paper , the sound power level measurement of Y;αngqin was performed in a reverberation chamber , and the sound output and the corresponding dynamic range were obtained by means of multi -channel measurement. The typical sound power levels of ytαngqin were then obtained when performing single notes , music scales and a piece of folk music under pp , mp , f and ff dynamics , respectively. It is suggested that the forte sound power and its spectrum when performing a music scale under f dynamic can be chosen to represent the sound power of Yangqin, and that the sound power dynamic range of ytαngqin can be specified by the range when performing a music scale under pp and ff dynamics.

Urban Canal Systems in Ancient China

Wu Qing-zhou

2007, 35(10):  61-69. 

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This paper intends to study the urban canal system in ancient China in several important aspects , e.g. the waterways inf1uence on site selection of cities , the planning and construction of urban canal systems , the types of the layouts and the features of ancient water cities , etc. Ten major functions of urban canal systems are summarized , including water supply , waterbome transportation , irrigation and aquaculture , military defense , draining of floods and waste water , flood storage and mitigation , fire fighting , ship sheltering , landscaping and recreations , as well as environment tempering. The paper provides rich examples to demonstrate the significant role that urban canal systems play in stabilizing urban sites , promoting industry and commerce development ,and improving living environment. By citing typical cases both at home and abroad , the author shows his disapproval of the destruction of urban canal systems in the course of modem urbanization , and emphasizes that urban canal system is one of the most important embodiments of a city. It is concluded that the existing urban canal systems should be well conserved so as to present unique urban outlooks characterized by both tradition and modemity.

Crack Statistic-Based Method for Bridge Performance Assessment

Han Da-pan Du Jiang

2007, 35(10):  70-77,104. 

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This paper proposes a new method for the performance assessment of concrete bridge , in which the capacity or the residual capasity of a bridge is estimated according to the statistic quantities of all the cracks on the bridge surfaces. The finite element numerical analysis instead of "real experiments" is performed to simulate the concrete cracking process , and the simulated experiments are designed to be orthogonal to reveal the
multivariate relationships between the bridge performance and the cracks. In these experiments , the importance of different factors affecting the multiple relationship is determined through a screening analysis , and the rela tionship between the performance and the cracks is illustrated by seuing up a regression model. Experimental results show that the regression model with fewer factors can yield accurate and reliable assesment results.Thus , the proposed method can be used as an effective means for the periodic assessments in bridge management system due to its feasibility , convinience and low cost.

Ultimate Strength of Reinforced Concrete Columns Strengthened by Circular Steel J acketing

Cai Jian Xu Jin

2007, 35(10):  78-83. 

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This paper presents an experimental research on 33 reinforced concrete columns strengthened by circular steel jacketing subjected to axial or eccentric load , and investigates the mechanical properties of the strengthened columns with different original axial compressive ratios , steel jacketing thicknesses , slendemess ratios and eccentricity ratios. Experimental results show that (1) the mechanical properties of the reinforced concrete columns are greatly improved by the strengthening; (2) the ultimate strength of the strengthened CQlumns decreases with the increase in slendemess ratio and eccentricity ratio; and (3) the effect of the original axial compressive ratio on the ultimate strength can be ignored. Furthermore , a practical formula is proposed based on the experimental results to calculate the ultimate strength of the reinforced concrete columns strengthened by circular steel jacketing. The calculated results accord well with the experimental ones.

Analyses of Nonlinear Temperature Response of Steel Structures

Wei De-min Jiang Xue-Zing

2007, 35(10):  84-90. 

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Based on the nonlinear finite element method and the total strain theory , the basic equations of the temperature responses at room and high temperatures are deduced , in which the effects of different parameters , such as the connection rigidity , the geometric nonlinearity , the material plasticity and the linear distribution of temperature along the section height , are all considered. A computer program is then developed and applied to the analysis of the nonlinear temperature responses of one-stoηand two-stoηsteel frame structures. The calculated results accord well with the correlative experimental ones , thus verifying the correctness of the proposed theory and the program. Moreover , a comparison of the calculated results with other calculated and experimental results is performed. It is found that the connection rigidity has great effect on the middle span deflection of the beam and the horizontal displacement on the top of the column , but has liule effect on the axial deformation of the column.

Thermal Degradation Behaviors of Cellulose Whiskers

Cheng Rong-shi Wiang Neng Ding En-yong Xue Feng

2007, 35(10):  91-98. 

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In order to improve the thermal stability of the cellulose whiskers obtained by the hydrolysis with sulfuric acid , two methods were adopted to treat the cellulose whiskers. One is the repeated desulfation with heating at 60℃ to reduce the hydrosulfate content , and the other is the neutralization with NaOH solution to neutralize the hydrosulfate on the surface. The results indicate that both the two methods can effectively improve the thermal stability of cellulose whiskers. As compared with microcrystalline cellulose , cellulose whiskers have a second pyrolysis stage at high temperature (more than 400 ℃) except the primary pyrolysis stage , and the final char yields are very similar in amount (3.5% - 5.0%). All these above-mentioned findings show that , for cellulose whiskers , the presence of extemal catalyst can only change the thermal decomposition pathway , and that the thermal pyrolysis and the final char yield are determined by the characteristics of the nano-sized particles. Moreover , the profile analysis of thermo gravimetric derivative curves shows that there are two remarkably competitive reactions in the primary pyrolysis stage of cellulose whiskers.

Biomimetic Preparation of the Composite for Bone Restoration and Mineralization Modulated by the Biomolecules

Wang Ying-jun Chen Xiao-feng Yang Chun-rong Deng Chun-lin Zhao Na-ru

2007, 35(10):  99-104. 

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BG-COL-HYA-PS porous composite for bone restoration was prepared via the biomimetic method using refrigeration-desiccation and nano-synthesis techniques The mechanism of bio-mineralization and biomolecular modulation of the composite in the simulated body fluid , in the cell culture fluid and in vivo , were respectively investigated by means of the techniques such as biomimetic mineralization in vitro , bioassembly , implantation to animals ,histological morphology observation , SEM/EDS and XRD. The results indicate that the natural extracellular matrixes such as collagen (COL) , hyaluronic acid (HYA) and phosphoserine (PS) play important roles in the modulation of mineralization. The prepared composite could effectively promote the new bone restoration.

Preparation and Properties of Lead -Free Piezoelectric Ceramics

Zhuang Zhi-qiang Huang Hao-yuan Wang Xin Wei Qun Mo Qing-ju

2007, 35(10):  105-110. 

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In order to protect the environment and produce environmentally friendly materials and electronic devices, the research and development of lead-free piezoelectric ceramics have been carried out in recent years.Based on the current research on lead-free piezoelectric ceramics , this work investigates the preparation and propertiesof Li- and Ta-doped sodium potassium niobate (LNKNT) ceramics. XRD was then adopted to analyze the microstructure of the ceramics. The results show that (1) the Ta-doped LNKNT ceramics with a Ta composition (x)of 10% - 20% possess a monoclinic perovskite structure at room temperature ， then forms a complete solid solution when the Ta composition is 17 % and 20% ; (2) the monoclinic and tetragonal phases coexist near the monoclinictetragonal phase transition temperature , The Ta compositional dependences of dielectric properties and piezoelectric properties are discussed in this paper. When x = 17%， the piezoelectric coefficjent , plane electro-mechanical coupling factor and dielectric constant of the Ta-doped LNKNT ceramic are 235 pC/N 、0.49 and 1293.5 , respectively.50 , the ceramic , which has been used to prepare a lead-free piezoelectric buzzer , meets the requirements of industrial application.

China's Building Energy System Calls for Creation and Municipal Planning

Hua Ben

2007, 35(10):  111-116. 

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In this paper , the Second Law Analysis of Thennodynamics is advanced for the energy supply modes of building HV AC and hot water system , which occupies 80% of building energy consumption. The theoretical basis to increase exergy efficiency from the traditional 10% to 65% is then pointed out. The corresponding technical approaches， based on the energy-conservative design of building envelop , should integrate the creation of low exergy-
loss air-conditioning tenninal technology with large-scope district cooling system (DCS) and distributed combined cooling , heating and power system (DES/CCHP) , fonning the new generation of Town Building Energy Purvey System. In order implement the creation of Town Building Energy Purvey System in China ，the paper pointed out the challenge and opportunity , and the importance of taking the experiences of developed countries and overcome the main barriers in idea and mechanism. Finally , the implementation practice steps for newly constructed towns and existing towns are suggested respectively; the significant role of municipal administration on planning , policy , organization and coordination are emphasized.

A H₂ S Intermediate-Temperature Fuel Cell with Nano-Composite Li₂ SO₄ Proton-Conducting Membran

Zhong Li Chuang Karl

2007, 35(10):  117-123. 

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A nano-composite Li₂SO₄ proton-conducting electrolyte and a new preparation procedure of membrane-electrode assembly (MEA) were developed for the electrochemical oxidation of H₂S. Instead of the traditional screen-printing method , in the MEA , both the anode and cathode catalysts were simultaneously pressed to form the cell with nano-composite electrolyte. This allows the design to possess some advantageous configurations that can diminish the Ohmic resistance between the electrolyte and the electrodes , enhance the mechanical and electrical properties , and improve the performance of fuel cells due to the membrane thickness reduction and the good contact between the electrolyte and the electrodes. The electrolyte was then characterized by scanning electron microscope (SEM) and electrochemical impedance spectrum techniques. The results indicate that the nano-composite materials improve the electrolyte integrity , and that no cross-over of H25 through the improved electrolyte occurs due to its high density , good compactivity and gas-impermeability. Moreover , MEA is stable in H25 stream. For a single cell with the configuration of H₂S, (MoS₂/NiS + Ag + electrolyte + starch)/Li₂SO₄ + Al ₂O₃/ ( NiO + Ag + electrolyte + starch) and air in a MEA thickness of 0. 8 mm and a Li₂ SO₄ to Al₂O₃ weight ratio of 65: 35 , the maximum power density is about 130 m W/cm² and the corresponding current density is about 200 mA/ cm² at 680 ℃ .

Synthesis of Fine Chemicals via Green Oxidation

Ji Hong-bing Qian Yu Li Zhong Wang Le-fu

2007, 35(10):  124-130. 

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As oxidation is widely used in the synthesis of fine chemicals , employing green methods into oxidation processes can effectively reduce the pollution and improve the atom economy. In this paper , some catalyst systems , such as recyclable and reused solid catalysts , efficient homogeneous metalloporphyrins and metal phthalocyanines , and the metal-free cyclodextrin catalyst system , were developed by using molecular oxygen and hydrogen peroxide as the oxidants. The results show that (1) when ruthenium is used as the active center , Ru-modified ferrite spinels , Ru-modified hydrotalcite and Ru-modified HMS zeolites are all proved to be effective catalysts in the presence of molecular oxygen; (2) when non-precious metals are used as active centers , nickel and vanadium are well fabricated to be effective catalysts; (3) as to the biomimetic oxidation , metalloporphyrins with simple structure can effectively convert cyclohexane to adipic acid , alkenes to epoxides and sulfides to sulfoxides; (4) metal phthalocyanines are also effective catalysts towards nitrotoluene oxidation to para-nitro benzoic acid; and (5) as a metal-free catalyst ， β-cyclodextrin can oxidize various organic compounds in water under mild conditions. All the above-mentioned findings indicate that solid catalysts and biomimetic catalysts can activate molecular oxygen or hydrogen peroxide to furthermore achieve green oxidation under mild conditions.

Characteristic Flows of Fluid and Flocculation Settling of Particles in Micro-Vortex Settler for Sugar Mills

Guo Si-yuan Zhou Shao-ji Li Lin

2007, 35(10):  131-136. 

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A micro-vortex settler with corrugated inclined troughs , which has been used for the clarification of filtrate from non-cloth vacuum rotary filter in several Chinese sugar mills , is introduced in this paper. The working principle of the settler is then discussed and the flows of the fluid in the corrugated inclined troughs are analyzed.Moreover , the corresponding velocity equations of hydraulic characteristic flows are deduced with certain simplification.
It is pointed out that , in the settler, the characteristic flows of the fluid that enhance the separation of floccule from the filtrate are the vortex flow on the upstanding corrugated plates and the secondary flow in the axial direction of corrugated inclined troughs , and that the velocities of both the vortex and the secondary flows increase with the increasing of main body flow velocity and with the decreasing of trough diameter. Simplified equations for the particle settling rates under such characteristic flows are deduced too. The results show that the settling rate of particles increases with the intensification of the vortex flow and the secondary flow. It can thus be concluded that the settling rate is enhanced by the characteristic flows in the settler. This may provide theoretical references for the modification of the novel settler.

Intergration of Separation and Coordination Reaction of Hesperidion in Ion-Exchange Chromatography Column

Yu Shu-juan Zhu Si-ming Zeng Xin-an

2007, 35(10):  137-142. 

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A novel technology about the integration of separation and coordination reaction of hesperidin with Cu²⁺ in ion -exchange chromatography (IEC)column was presented and performed in this paper. Ion -Exchange Chromatography , UV -vis , XRD FTIR and ¹ H -NMR were adopted to analyze the mechanism of the technology. The results show that it is feasible to produce new medicines with high biological activity by the column reaction between metal ions (Cu^{2 +}) and Chinese medicine , such as hesperidin. The reaction mechanism lies in the fact that as a soft base , anion hesperidin on resin can easily coordinate with Cu²⁺ insolution due to the electrostatic attraction between them , which modifies the molecular state and hydrophobic state of hesperidin by the "centralizing effect" of Cu²⁺ on hesperetin and the "embedding effect" of rutinose on hesperetin. As a result , the anions in the regenerant go through the Nemst film to replace hesperidin , and hesperidin disperses in the liquidphase due to the overlapping of
electron clouds , thus contributing to the integration of separation and coordination reaction.

Research on Enzyme Improving Technology

Guo Yong

2007, 35(10):  143-146,161. 

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Although enzymes possess high catalytic efficiency and good substrate specificity , their activities and stabilities often can not meet the requirements of application. In order to improve the catalytic properties of enzymes , the author and his group have devoted themselves to the researches of enzymatic molecular modification , enzyme immobilization , non-aqueous enzymatic catalysis and directed enzyme evolution in the past two decades , finding that the catalytic properties of enzymes such as activity and stability can significantly be improved by enzyme improving technology. This paper reviews the achievement and progress in the field of enzyme improving technology made by the author and his group.

Sinusoidal Frequency Estimation ßased on Inversion Integral Equation

Wei Gang Li Dao-yuan Chen Fang-jiong

2007, 35(10):  147-151. 

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In traditional frequency estimation algorithms , there exists a general problem arising from the discrepancy between the costly computation and the unsatisfactory performance under low SNRs (Signal-to-Noise Ratios). In order to solve this problem , this paper proposes a new frequency estimation algorithm based on the IIE (Inversion Integral Equation) approach. In this algorithm , FIT (Fast Fourier Transform) is used to roughly estimate the frequency , based on which an IIE is constructed according to the narrow-band signal resulting from FIT. Then , the fine frequency is estimated by calculating the parameters and characteristic frequency of the IIE. Simulated results show that the proposed algorithm is of good performance and moderate computationaI requirement under low SNRs.

Fuzzy Error Concealment Algorithm for Video Sequence Transmission

Xie Sheng-li Li Zheng-fang Zhou Zhi-heng Zeng De-lu

2007, 35(10):  152-155. 

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An error concealment algorithm based on fuzzy edge detection is proposed as a tool at the decoder side to recover the image information lost during the video sequence transmission. For a lost block , a fuzzy edge detector is used to obtain the edge information on the boundary pixels of its four neighboring blocks. With the obtained edge information , an energy function for boundary matching error is constructed. Then , the motion vector corresponding to the minimum of the energy function is used as the estimation of motion vector of the lost block. Simulated results show that , as compared with the existing error concealment algorithms , the proposed algorithm can recover the image with higher quality in both subjective visual evaluation and objective numerical comparison.

A Novel 2.45 GHz Quasi-Elliptic LTCC Low-Pass Filter

Chu Qing-xin Liang Qi-xin

2007, 35(10):  156-161. 

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This paper presents a novel2. 45 GHz quasi-elliptic low-temperature co-fired ceramic (LTCC) low-pass filter with spiral transmission lines , and proposes the analytical equation to determine an positions of the transmission zeros at the rejection area. By considering the parasitic coupling effect of spiral transmission lines in the actual LTCC structure , the equivalent circuit of the filter is modified , which enables the simulated scattering parameter curves of the equivalent circuit to accord well with the measured ones. It is indicated by measurement that the proposed low-pass filter is of good perfo 口nance and meets the requirements of application well.

Theoretical Investigation and Simulation of Process Neural Networks

Zhu Xue -feng Ye Tao

2007, 35(10):  162-167. 

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The process neural networks (PNNs) are networks that adapt to the process of signal input , whose elementary unit is the process neuron (PN) , an emerging neuron model. Both essential difference and close correlation exist between the process neuron and the traditional neurons , for example , PN can be approximated by traditional neurons with arbitrarγpreclslOn. In this paper , the PN model and some PNNs are introduced. Then , two PN
approximating theorems are presented and proved in detail. Each theorem gives an approximating model to the PN model , i. e. , the time-domain feature expansion model and the orthogonal decomposition feature expansion model. Moreover , a corollarγis given for the real-valued output PNN based on the second theorem. Mterwards , a simulation of analog signals is carried out , showing that the PNN can well suppress the white noises contained in signals. Finally , some problems about PNNs are discussed and further research orientations are suggested.

Special Threshold Secret Sharing 岛lethods and Their Applications

Tang Shao-hua

2007, 35(10):  168-171,177. 

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Based on the practical requirements of the electronic bidding system , the concept of special threshold secret sharing is proposed , which owns the features and properties of that the designated person must participate , that a group acts as a unit , or that the designated group must participate. Corresponding to the actual requirements , some secret sharing algorithms are designed to solve the practical problems by adopting the multi-threshold method based on Shamir's secret sharing principle , which include the one that the designated person must participate , the one that a group acts as a unit , and the one that the designated group must participate. It is shown by theoretical analysis that the proposed algorithms are secure and effective. Moreover , the designed algorithms are practically applied to an electronic bidding system. The results indicate that the system runs stably and the algorithm works efficiently.

Fault Diagnosis Based on Wavelet for Commutation Failures in HVDC

Zhang yao Lin Ling-xue Zhong Qing

2007, 35(10):  172-177. 

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This paper proposes a method to identify different causes of commutation failures in the High-Voltage Direct Current Transmission (HVDC) system. By using the technique of wavelet multi -resolution analysis (MRA) ,the transient signals generated by the faults are decomposed into different resolution scales. Then , the features of each fault are extracted using the wavelet signal processing methods such as scale energy and scale entropy. Moreover, two auxiliary parameters are defined as the criteria for the identification , and four thresholds are set to distinguish the commutation failures from DC line faults. Simulated results indicate that there exist certain distribution regularities for the scale energy and scale entropy of transient signals with different HVDC faults , and that the criteria based on these regularities can make effective and reliable diagnosis of commutation failures.

Sneak Circuit Characteristics of Switch-Mode Converters and the Corresponding Analysis Method

Zhang Bo Qiu Dong-yuan

2007, 35(10):  178-184. 

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Based on the fact that the sneak circuit phenomena are found in resonant switched capacitor (RSC) converters, this paper proposes a graphic method to analyze the sneak circuit , obtains the generation laws of sneak circuit according to the energy equilibrium , and then summarizes a general analysis method for sneak circuits in switch-mode power converters. The proposed method , whose correctness is finally verified by experiments , can be used for the safety diagnosis in design process , and for discovering , eliminating or utilizing sneak circuit paths.

AppIication of Laser-Induced Breakdown Spectroscopy to Combustion Diagnosis

Lu Ji-dong Liu Yan Li Ping

2007, 35(10):  185-188,193. 

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In this paper , fundamentals of laser-induced breakdown spectroscopy (LIBS) studies are briefly reviewed first , including the experimental set-up , the qualitative and quantitative analysis methods for the spectrum. Then , the studies on combustion diagnosis by LIBS are introduced in detail. Moreover , a quantitative analysis of residual carbon in fly ash is carried out , and the characteristics and composition of coal are finally analyzed. The results show that (1) the carbon content in fly ash measured by LIBS accords well with that measured by the traditional method of W eight -Combustion; (2) the coal samples with different coalification degrees show different plasma time-resolved spectral characteristics; (3) in the same experimental conditions , the plasma temperature increases with the coalificatÏon degree; and (4) the coal content measured by LIBS coincides with that measured by the traditional method. The present study verifies the feasibility of combustion diagnosis by LIBS and lays a foundation for further studies and experiments of combustion diagnosis.

Mechanism and Consequence Assessment for BLEVE of Liquefied NaturaI Gas

Ma Xiao-qian Wang Jing-jing

2007, 35(10):  189-193. 

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In this paper , the van der Waals equation is used to describe the gas-liquid phase transition of superheated liquefied natural gas (LNG) , which is found to display the characteristics of cusp-type catastrophe. The results show that , when the pressure changes from O. 1 to O. 8 MPa , the corresponding unstable superheated degree is in the range of 143. 5 -150.7 K. According to the energy balance theo巧， the superheating energy increases with the temperature in the process of boiling liquid expanding vapor explosion (BLEVE) due to the failure of the tank. Moreover , the overpressure of explosion shock wave and the safety distance for people in BLEVE are estimated. The present research lays theoretical foundations for the accident prevention and consequence assessment of LNG during transportation and storage.

Forecastability Analysis and Combination Forecast AIgorithm for Short-Term Traffic Flow of Related Intersections

Xu Jian-min Fu Hui Xu Lun-hui

2007, 35(10):  194-197,232. 

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In this paper, first , the related intersection is defined according to the relationship between traffic flow time series. Then , several forecastability indexes for the short-term traffic flow of related intersections are proposed for the quantitative analysis , and the computation method of the first Lyapunov index to traffic flow time series is described.Moreover , a nonlinear combination forecast model using RBF neural network is set up based on a set of forecast models after the forecastability analysis. Thus , a combination forecast algorithm for the short-term traffic flow of related intersections comes into being. The results of simulation indicate that the proposed method is more efficient than the single forecast method.

Fatigue Lives of RC Beams Strengthened with Carbon Fiber Laminates Under Bending Loads

Huang Pei-yan Zhou Xu-ping Yang Yi Niu Peng-zhi Zheng Shun-chao

2007, 35(10):  198-204. 

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The fatigue behavior of RC (Reinforced Concrete) beams strengthened with FRP (Fiber Reinforced Polymer ) is an important subject in civil engineering in the world. In this paper , 18 RC beams (1850 mm x100 mm x 200 mm) strengthened with CFLs (Carbon Fiber Laminates) are divided into 4 groups and are tested to investigate their fatigue behaviors under bending loads. Based on the data of fatigue test and theoretical analyses , S-N and P-S-N curves of the RC beams strengthened with CFLs are obtained according to the new conceptions of permissive and extreme fatigue lives , finding that the ratios of the permissive and extreme fatigue strength to the ultimate static strength are respectively 65% and 67%. The relationships among the mid-span deflection , the loading cycle number, the individual fatigue life and the stress level are then deduced and validated. Afterwards , a new method that only needs some nondestructive experimental data of fatigue (the fatigue load cycles n recommended here is 100 - 1000) is proposed to predict the individual fatigue life. The proposed prediction method is finally validated by the fatigue tests of another three RC beams strengthened with CFLs.

Phenomenon of Running-in Electricity in Running-in Experiments and the Corresponding Analyses

Xie Xiao-peng Wang Ze-gui

2007, 35(10):  205-209. 

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In the running-in experiments , there exists a running-in electricity phenomenon among the running-in , the steel , the involute and the spur-gear pairs in any of three kinds of running-in oils , namely , the electric resistance hetween the gear pairs measured hy digital or index ohmmeter is prohahly negative. This phenomenon is a surface electric phenomenon in the presence of the metal pair wear. In this paper , the mechanism of the running-in electricity phenomenon is investigated , finding that the phenomenon hecomes more ohvious when the difference in oxidative wear of the two surfaces increases. Moreover , a method to judge the wear status of a friction pair by measuring the electric resistances hetween the pair is put forward , also the method to revise the measured data of oilfilm electric resistance.

Improvement and Anti-Noise Performance Analysis of Window-Length Changing Phase Difference Correction

Ding Kang Yang Zhi-jian

2007, 35(10):  210-213. 

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This paper presents a method of improved winodw-length changing phase difference correction to estimate the frequency of harmonic signal. As compared with the unimproved one , the proposed method only needs to perform one fast Fourier transelation (FFT) and one single-point discrete Fourier translation (DET). Thus，the pro-cessing speed is greatly increased. The anti-noise performance of the improved method is also investigated in thispaper , and the variance equation of the frequency estimation error in the presence of Gaussian white noise is then deduced. Simulation is finally performed to verify the correctness of the variance equation. The results reveal the good anti-noise capability of the improved method.

Application of Eigen-Mode Matching Theory to Propagation of Classic Wave

Liu You-yan Hou Zhi-lin Yao Yuan-wei kuang Wei-min Fu Xiu-jun

2007, 35(10):  214-220. 

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Based on the calculation method of grating structure , the authors have developed an eigen-mode matching theory to study the propagation of classic waves in periodic systems. The proposed method has been applied to the investigations of phononic crystals with solid/ solid , liquid/liquid and air/rigid body types , and has been expanded to the investigation of frequency-band structure and transmission properties of liquid surface wave with topology bottom. The effectiveness of the proposed theory is verified by numerical results.

Analytical Current and Capacitance Models of Polysilicon Thin-Film Transistors

Zheng Xue-ren Deng Wan-ling Chen Rong-sheng

2007, 35(10):  221-226. 

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This paper presents a surface-potential-based analytical current and capacitance model of polysilicon thin-film transistors (poly-Si TTs) for circuit simulation , in which the non-iterative numerical algorithm is adopted to calculate the surface potential of poly-Si TFfs as a function of terminal voltage , thus greatly enhancing the efficiency of the proposed model. Based on the analytical calculation of surface potential and the charge sheet approach , the current-voltage model considering both the small geometry effects and the kink effect is developed. Moreover , a charge-based gate capacitance model is derived. It is indicated that the current and capacitance model is continuous and accurate across the linear and saturation regions without any unphysical interpolation scheme. A comparison between the data obtained by the model and those by experiments shows that the results accord well with each other , which verifies the correctness of the proposed model. S0 , it can be concluded that the proposed model is suitable for the incorporation into circuit simulators.

Bifurcation Method and Explicit Periodic Wave Solutions to Generalized CH Equation

Liu Zheng-rong Ali Mohammed Kayed

2007, 35(10):  227-232. 

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Bifurcation method of dynamical systems and numerical simulation are used to look for the explicit periodic wave solutions to the generalized CH equation. First , the planar system corresponding to the nonlinear partial differential equation is established. Then , the bifurcation phase portraits of the traveling wave system are drawn ,and the special orbits corresponding to the explicit periodic wave solutions are detected by numerical simulation. Finally, via the special orbits , the elliptic functions and the elliptic integrals , the explicit periodic wave solutions are obtained.