Table of Content

25 February 2005, Volume 33 Issue 2

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Preparation and Properties of La-Doped BaTiO₃ Ceramics(Ⅰ)：By a Heterogeneous Nucleation Processing Technique

Zhuang Zhi-qiang Su Tao-long Liu Bo

2005, 33(2):  1-5. 

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Hvdrothermally-synthesized barium titanate powders were coated with La(OH)₃ through a heterogeneous nucleation processing technique with La(NO₃)₃ as the La source.The pH value during the heterogeneous nuclea-tion was calculated based on the theory of solubility product. By controlling the pH value in dispersed BaTiO₃ sus-pension, La₂O₃-coated BaTiO powders and ceramics with a homogeneous and stoicheometry composition of (Ba_1-3x/2M/La )TiO₃ were then prepared. Meanwhile,the influence of La content on the sintering behaV or,phaLse structure.resistivity and dielectric constant-temperature dependence of the La-doped BaTiO₃ ceramics added with SiO₂ was discussed. Expe:rimental results demonstrate that the La-doped BaTiO₃ ceramics with homogeneous and stoicheometry composition CaD．easily be prepared by the doping method mentioned above· It is also found that the Curie temperature of the prepared BaTiO3 ceramics decreases linearly with the increase of La₂ O₃ content,and that more La is needed to make a BaTiO semicondsucting ceramic derived from the method than by an oxide-mixing re-action method.

Performances of Photovoitaic Cells Based on Se-Containing Low-Bandgap Polymer

Tian Ren-yu Yang Ren-qiang Zhou Qing-mei Peng Jun-biao Cao Yong

2005, 33(2):  6-9,18. 

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Se-containing low-bandgap polymer-poly[2,7-(9,9-dioctyl)fluorene-co-5,5’-(4,7-diselenophenyl)-2,2’-v1-2,1,3-benzoselenodiazole](PFSeBSe)was used as the electron donor in order to expand the spectral re-sponse region of polymer photovohaic cells(PPVCs).Single-layer PPVC was made by blending PFSeBSe with C60 derivative(PCBM),the electron acceptor.The results indicate that the optimal blend ratio of PFSeBSe to PCBM is about 1:4 (in mass),and that a maximum power conversion efficiency of 0.423%under Air Mass 1.5 solar simu-lat0r(100 mW•cm^-2 ),can be obtained when LiF/Al is used as the cathode.Th e photosensitivity of the cell ex-pands to more than 700 nm．which is 30 ~50 nm red-shifted compared with the results in the literature,suggesting a better match of the absorption of the blend system to the terrestrial solar spectrum.

Dependences of Physical Properties on Composition in Titanate Glasses

Deng Zai-de Liu Xue-jing Ying Ting-zhao Yin Bing

2005, 33(2):  10-13. 

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With BaO-TiO₂ -SiO₂ -R_m O_n glasses as the research object,large-sized titanate glasses with a refrac-tive index of 1.8338~1.9189 were prepared by the melting method.In the preparation process,the mass fractions of SiO₂ were respectively controlled at 15%,12% and 10%;the sums of the mass fractions of BaO and TiO₂ were respectively controlled at 73%,76% and 78% with different ratios of BaO to TiO₂.The refractive indexes and the
densities of the prepared glasses were respectively measured by using a W YV-V prism and by means of the Archi-medes method.The results show that,with the increase of the mass ratio of BaO to TiO₂,the refractive indexes of the glasses decrease,while the densities first increase and then decrease.At the mass ratio of 2.077,the density shows a maximum .The above-mentioned results were finally qualitatively analyzed according to the rules of additive and polarization.

Viscoelasticity and Its Mechanical Model of Polymer

Zeng Guang-sheng Qu Jin-ping

2005, 33(2):  14-18. 

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As the classical mechanical model can not correctly depict the viscoelastic behaviors of polymer,a new mechanical model which can characterize various viscoelastic behaviors is proposed.This model can corectly de-scribe the wriggle-change and stress relaxation behaviors of polymer.Then,with the help of a two spring-two pistonsystem (the rigidities and the viscidities are respectively different)and by employing the principles of rheology and elasticity dynamics,a novel physical model and its coresponding mathematical expressions for polymer viscoelasti-city are obtained.The viscitic flow characteristics of polymer under a vibrating load were finally discussed,which leads to the following conclusions:(1)the viscositic flow of polymer is directly propo~ional to the amplitude of the swing;(2)there is an optimal~equency,at which its effect on the viscositic flow of polymer is the greatest.

Preparation and Film Performance of Self-Crosslinking Fluorine-Containing Latex at Room Temperature

Qin Zong-gen Tu Wei-ping Xia Zheng-bin Shen Liang-jun

2005, 33(2):  19-23. 

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A kind of fluorine-containing latex was prepared by means of semicontinuous emulsion polymerization and self-crosslinked at ambient temperature.Various factors affecting the performance of the latex film,such as the N-MA content(mass fraction,the same below),the film formation temperature,the content of the fluorine-containing monomer and the film thickness,were then studied. Moreover,the glass transition tempe rature and
the surface prope rty of the film were respectively determ ined by means of DSC analysis and Wilhelmy method· The weatherability of the fluorine-containing polymer was also investigated by the artificial accelerated ageing test.The resuIts show that the pe rform ance to price ratio of the obtained latex is better than those of the fluorine-containing latexes on the market.

Simulation of Ozone Reaction with P-Nitrophenol Solution in Bubble Column

Shen Hui-fang Chert Huan-qin

2005, 33(2):  24-28. 

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The absorption and mass transfer process of ozone reaction with p-nitrophenol solution in the bubble column was investigated in this paper.First,ab sorption experiments were carried out in semibatch mode by continuously injecting gaseous ozone into a bubble column containing p-nitrophenol solution at 298 K,and the ab sorption process was simulated.Next,the mass balance equations of ozone absorption in p-nitrophenol solu-tion were estab lished by using the complete mixing model.Then,by utilizing the Matlab ODE program,the simultaneous equations of the mass balance equations and the enhancing factors were solved,thus simulating the variations of ozone concentration and p-nitrophenol concentration in the ab sorption process.The simulated re-suits were finally compared with the measured ones.It is shown that.at appropriate pH.the simulated results
accord well with the measured ones as far as 80%p-nitrophenol is degraded,while there is a certain deviation when p-nitrophenol concentration declines to a certain level.It is also indicated that the complete mixing model is feasible to describe the fluid flow states in both gas and liquid phases in a short bubble column.

Numerical Simulation of the Heat Transfer and Performances of Concavo-Convex Flowing Resistance Tube

Zhang Ya-jun Xing Hua-wei Deng Xian-he

2005, 33(2):  29-33. 

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A 3-D numerical simulation of the flow and heat transfer process in a concavo．convex tube was carried out by using the Fluent Software.Thus,the velocity and temperature distributions inside the tube were obtained.By the comparison between the simulated results of the concavo-convex tube with those of the smooth tube,it is indicated that the resistance coemcient and the heat transfer coemcient of the concavo.convex tube are much larger
than those of the smooth tube,and that,comparing the concavo-convex tube with the smooth tube,the resistance coemcient ratio increases with an increasing Reynolds number.while the heat transfer coeficient ratio decreases. It is also shown that,in the simulation range,when Reynolds number ranges from 2757.76 to 13788.79, the resis.tance coeficient ratio and the heat transfer coeficient ratio respectively vary from 5.530 8 to 8.3663 and from 2.289 to 1.585.The overall evaluation affirms that the integrate property of the concavo-convex tube obviously im-proves at a lower velocity,which means that the concavo-convex tube is adaptive to the heat transfer enhancement at lower velocity.

An Improved Mathematical Morphology Method and Its Application to Power Quality Monitoring

Ouyang Sen

2005, 33(2):  34-38,59. 

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By analyzing the defects of the traditional morphology filtering method,an improved mathematical morphology (MM)method is proposed to deal with the data noise in the power quality(PQ)processing.In this method,appropriate structural elements are selected and different structural elements and their serf-adaptive weighted combination are used to form a treatment method for perturbation signals with excellent perform ance.The proposed
method can effectively de-noise the PQ signals without changing the local characteristics of the original signals.The design kernels and steps of the proposed method are also introduced. Simulated results and practical application show that the proposed method is practicable and possesses the advantages of simplicity,high calculation speed and easy hardware implementation.

An Algorithm for Tuning PID Parameters Based on Satisfactory Degree

Wu Xiao-chao Wu Jie Li Quan-guo

2005, 33(2):  39-42. 

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A controller for the on-line tuning of PID(Proportional-Integral-Derivative)parameters based on the sa-tisfactory degree and genetic algorithm is proposed.With the theory of satisfactory solution,the satisfactory func-tions of over-shoot,rise time and setting time of the system response are designed,and the three parameters k_p,k_iand k_d of the PID controller are obtained by means of gaenetic algorithm.These three parameters are used as the base values for the on-line tuning of PID parameters.Then,by designing the nexus functions between the tracking error and k_p,k_i,k_d,the PID controller parameters are adjusted online,thus improving the static performance,dy-namic perform ance and robust perform ance of the control system.The results of Matlab simulation show that the proposed PID controller is valid.

Control of the Double·Link Inverted Pendulum by Using Takagi-Sugeno Model Based on Gradual Fuzzy Neural Network

Zhu Xue-feng Zhou Wen-bin Chen Hua-yan

2005, 33(2):  43-47. 

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A new control method is proposed by using the gradual fuzzy neural network.In this method,the Taka-gi-Sugeno fuzzy neural network controller and gradual fuzzy control rules are adopted to stabilize the double-link in-verted pendulum. Moreover,Genetic Algorithm is used to optimize the parameters of the Takagi-Sugeno fuzzy con-troller in 4 steps.Experimental results indicate that,only with 20 rules，the gradual fuzzy neural network controller
can stabilize the double-link inverted pendulum with good effect and strong system robustness.

Realization of the Switching Voltage-Stabilization Power with High Current andMult-iOutput

Li Xin Liang Yuan-wen Zhang Cong-li

2005, 33(2):  48-51,64. 

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In order to overcome the difficulties in voltage-stabilization and current-limitation in the secondary output of the voltage-stabilization power with high current andmulti-output ,a second-side pos-tregu lator technology based on the magnet ic saturation property is proposed. According to this technology, a novel switch ing power is then designed.Simulated and experimental results indicate that the proposed voltage-stab ilization power attains an efficiency of 85% , and a stability up to 98. 5%. The application of the proposed power to the practice shows that the power is of both practicalva lue and promotional significance

Application of the Hole-Position Image Identification Technique to the NC Machine for Toothbrush-Hair Planting

2005, 33(2):  52-55. 

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In order to improve the programming accuracy and eficiency during the NC machining process by toothbrush-hair-planting machines,a hole-position image of the toothbrush head was firstly obtained with the help of a scanner.Then,based on the image identification technique,the data processing technique and the platform of Visual C + +.NET.a program of the NC machining by toothbrush-hair-planting machines was generated.This process
includes the aspects of image inputting,edge position limitation of the image,median filtering,outline distillation,image regularity and calculation of the hole parameters.The experimental resuhs show that the proposed method is feasible and effective,with a precision that can meet the production requirements.It can be used to locate the hole position accurately and rapidly,thus lessening the time cost of the supplementary machining.

Automatic Modeling for Modular Fixture Components Based on SolidWorks

Zhang Mao-peng Chen Wei-fang

2005, 33(2):  56-59. 

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In order to reuse the experiences in the design of modular fixtures with typical function structures.an automatic component modeling method on the platform of 3-D drawing software SolidWorks is proposed on the basis of assembly restriction equations.The automatic modeling principle,the method f0r building component template.the extraction of assembly parameter equations,the semantic analysis of assembly parameter equations as well as the method of assembly component dimension-driving are then analyzed.Based on these analyses,a component library system for modular fixtures is set up,and a case study is presented,thus overcoming the difficulties in automatic component modeling and providing a foundation for the automatic assembly and design of fixtures.

Algorithm and Implem entation of a Secure Speech Communication System

2005, 33(2):  60-64. 

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A speech communication system with high security was designed to overcome the trouble of eavesdropping. In this system ,a new 256-bit block cipher-Must 2 and a pseudorandom number generator-Must-Rnd as well as a high-security public key cryptosystem for a session key are employed.Thus,the session key caused by Must-Rnd is transmitted to the far end of the telephone for the real-time speech encryption and decryption by Must2.The proposed system is finally implemented on the TMS320VC5402 Digital Signal Processor(DSP)with good audio quality.

Single Sign-on Protocol for Web Services

Zheng Dong-xi Tang Shao-hua Li Shao-fa

2005, 33(2):  65-69. 

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In order to securely authenticate users in a Web-service-based cross·application system,a protocol for the single sign·on in a cross·application system is proposed by using the single sign·on scheme.It is named Web Services Single Sign·on(WSSS).This protocol is based on the existing security specifications for Web services.The architecture,messages and flow of the protocol are then described in detail.Moreover,the description and a-nalysis of the proposed protocol are carried out by using the formalization method and a security analysis of the pro-tocol is made.The single sign-on services defined in WSSS can be applied to various Web applications to provide Web-service-based authentication.

Improvement of Characteristics in the Saturation Region of n-MOSFET Using Backsurface Ar Bombardment

Chen Ping Huang Mei-qian Li Xu Li Guan-qi

2005, 33(2):  70-74. 

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Ar ion beams with the energy of 550 eV were used to bombard the backside of n·MOSFET chip to im-prove the direct current characteristics and overcome the low-frequency noise of the device in the saturation region.The direct curent characteristics include the following aspects:the transconductance,the threshold voltage and the effective mobility of the surface inversion layer cartier.The results indicate that,as the bombardment time increa-ses,the transconductance and the efective mobility first increase and then decrease,while the change tendency of the threshold voltage is on the contrary.Th e low-frequency noise obviously decreases after the bombardment.It is proved by experiments that all these changes are due to the trap density variation on the Si- siO₂ surface and the fixed charge density variation in SiO₂.

Identification of Structural Crack Groups by Means of Wavelet Method and the Numerical Simulation of Crack Groups

Liao Jin-xiang Yuan Ming-Wu

2005, 33(2):  75-78. 

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The aim of this research is to identify the damages of bridges by using relatively simple methods and to monitor the health situations of the bridge structures.Th is research is based on the fact that cracks usuallv exist in the form of crack groups. By analyzing the relationship between the Lipschitz exponent and the wavelet vanishing moment,the characteristics of the signal breaking points are expressed. based on the multi.scale change rules of the maximum value of wavelet transform.Thus,a method is proposed to determ ine whether there exist singularitiv points in the signal.and where the singularity points are located.By applying the proposed theory to the static force simulation of the finite element model for simple-supported beams with cracks.the oceurrence and location of the crack groups are then determ ined.Th e results indicate that the proposed method is of greater precision, more facili-ty and lower cost than the conventional method.

Resolution of High-Noisy Overlapped Analytical Signals by Means of Continuous Spline Wavelet Transform

Wang Li-shi Zhang Yong-qing Mo Jin-yuan

2005, 33(2):  79-81. 

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The continuous spline wavelet transform is employed to the resolution of high-noisy overlapped signals in analytical chemistry to obtain the location and the number of the overlapped peaks.The effects of the signal-to-noisy ratio(SNR),the overlapping degree and the peak height ratio between two adjacent peaks on the resolution aye then discussed．The results show that,by using the continuous spline wavelet transform ,the location and number of the overlapped peaks can be obtained when the SNR of the signal is down to 1.Moreover,the high-noisy over-lapped signals can be resolved well,thus providing references to the qualitative and quantitative analyses of the complex signals of low-content multi-component substances.It is also indicated that,comparing with the discrete wavelet transform,the continuous spline wavelet transform is of the advantages of simplicity and quickness because a data number 2ⁿ (n is an integer)and a multi-resolution are not needed.

Antiviral Activity of Extracellular Polysaccharide from Porph~ ridium sp．Against CVB₃ Virus

Liu Shi-sheng Wei Dong Zhu Gui-fang Wang Yi-fei Li Lin

2005, 33(2):  82-85,90. 

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Three components,named ESPS₀,ESPS_1.0 and ESPS_1.6,were separated from extraeellular polysaccha-ride(ESPS)of Porphyridium sp.by NaC1 gradient elution with Q Sepharose Fast Flow gel.ESPS₀,ESPS_1.0 and ESPS_1.6 account for 44,2%(in mass,the same below).20.3%and 16.4%of the total ESPS,their protein con-tent were at 0,7.8%and 7.6%,SO₃-radical content were 16.3% ,11.6% and 8.3%,respectively.By in vitro anti-CVB₃ activity test to the three components,the results show that their mass concentrations of half inhibition to virus were at 2.03,0.51 and 0.53 mg/L,and IT values were at 61.6,245.1 and 235.8,respectively.Under the same conditions,the mass concentration of half inhibition to virus and IT value of the positive control drug Ribavirin were at 31.25 mg/L and 16.0.They indicate that the anti·CVB₃ activity of all the three components were higher than Ribavirin.

Function Bar Code of the Stimulus and Response in Neural System

Liu Shen-quan Fan Tao

2005, 33(2):  86-90. 

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In order to investigate the code and the mode of the potential spike in a neural system,a mode of the function bar code of the external stimulus and the spike response in a neural system is constructed by using the WinnerLess Competition model in olfactory processing networks.This mode is based on the property that all poten-tial spikes exist at the same time or no spike exists in a neural cell.It connects the external stimulus with the spike
response in a limited function bar code form ,thus presenting a theoretical cognizable mode of the stimulus and re-sponse in a neural system. Moreover,a new method to study the potential spike mode and code is proposed,which can connect the code theory and the experimental data of the potential spike together.

A Two-Factor Model for Pricing Corporate Bonds

Yang Li-hong Qin Dao-li Yang Xia

2005, 33(2):  91-93,98. 

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By considering the characteristics of the corporate bonds in China such as long cycles,big fluctuations and great possibility of default risk,it is demonstrated that holding the bonds with default risk actually means hol-ding a portfolio by buying bonds without default risk and selling European put options at the sanle time.Further-more,a two-factor model for pricing corporate bonds is proposed by using the trinomial tree model and taking the
default risk into account.This model includes two stochastic factors,namely,the corporate value and the interest rate.

Optimal Investment Decision in the Fixed Consumption Style

Ming Zong-feng Guo Wen-jing

2005, 33(2):  94-98. 

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An optimal portfolio selection problem in the fixed consumption style is investigated under the mean-vari-ance framework.In this investigation,the cash flow is divided into two parts:one is used to keep the fixed con-sumption,the other is used to the investment.Then,with the assumption that the consumption of an investor is the continuous or piecewise continuous function of time,the corresponding optimal investment decision and the efective
frontier are derived by using the stochastic linear-quadratic control.Finally,the influence of consumption on the in-vestment decision and the efficient frontier are analyzed.

Bifurcation and Stability of the Steady-State Solutions to a System with Cross-Difusion Effect

Dai Wan-yi Fu Yi-ping

2005, 33(2):  99-102. 

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The aim of this paper is to investigate the bifurcation and stability of the positive steady-state solutions to a mathematical biology model of two competition species. These two species interact with each other under the cross-difusion effect.In this investigation,the spectral analysis method and the bifurcation theory are employed to analyze the stab ility of the semitrivial steady-state solutions.Then,by respectively using the growth rates a and b as bifurcation parameters,the existence and stability of the nontrivial positive steady-state solutions from the semitrivial steady-state solutions are obtained.Th e above-mentioned results are finally applied to a specific biology model,with the conclusion that there are nontrivial positive steady-state solutions when a and b Iie in some specific ranges.The necessary and sufficient conditions for the asymptotical stability of the solutions ale also proved.