2011 Vol.17

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    Direct Deoxidization of Ti-Bearing Compounds and  Selective Extraction of Titanium Alloys
    ZOU Xing-li, LU Xiong-gang, LI Chong-he, ZHONG Qing-dong, DING Wei-zhong
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 1-6.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract3231)      PDF(pc) (3474KB)(1586)       Save

    Direct deoxidization of Ti-bearing compounds was done by using solid oxygen-ion membrane (SOM) molten salt electrolysis and selective extraction of titanium alloys simultaneously. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses show that the Ti5Si3 alloy can be extracted directly from Ti-bearing blast furnace slag. Metallic impurities such as calcium, magnesium and aluminum were completely removed from products during electrolysis. In addition, TiFex alloys can also be obtained directly from deoxidized ilmenite (FeTiO3) in molten salt. Finally, the electro-deoxidation processes are discussed.〖HJ〗

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    Optimization of BaCoO3 Based Perovskite by B-Site Compositional Tailoring
    LIU Xu, DING Wei-zhong, SHEN Pei-jun, LIU Jiao, WANG Hai-hai, GENG Zhen
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 7-12.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract4469)      PDF(pc) (1522KB)(1339)       Save

    BaCo0.9-xFexNb0.1O3-δ(BC0.9-xFxN0.1O, x=0.1,0.2,0.3,0.4) and BaCo1-yNbyO3-δ(BC1-yNyO,y=0.10,0.12,0.14,0.16) were prepared in a conventional solid state reaction process. The influence of iron and niobium doping level on crystal structure, grain size, structural stability, and oxygen permeation of BC0.9-xFxN0.1O and BC1-yNyO compounds was investigated systematically. Increase of iron and niobium doping content resulted in the increase of the structural stability of oxides and the decrease of oxygen flux. The niobium doping level in oxides could enhance stability and refine the grain size of compounds more effectively than Fe. The oxygen flux of BaCo0.88Nb0.12O3-δ with 1 mm thickness reaches 2.02 mL·cm-2·min-1 at 850 ℃ under air/helium condition.

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    Exploration of the Next- Generation Iron- and Steel-Making  Technology
    HONG Xin, ZHENG Shao-bo, ZHANG Jie-yu, XU Jian-lun, YOU Jing-lin, WANG Xing-qing
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 13-20.  
    Abstract2510)      PDF(pc) (3831KB)(2349)       Save

    The traditional iron and steel industry are characterized by its huge scale, heavy consumption of energy and resources, and complicated technical processes. Due to the limited energy and resource deposit, the concept of circulation economy needs to be introduced in the next generation iron and steel industry. New processes must be developed through technical innovation, and converted progressively to three main functions: metallic material preparation, energy conversion, and social wastes treatment. With this strategy, fundamental studies have been carried out at the Key Laboratory of Modern Metallurgy & Materials Processing, Shanghai University. The researches involve hydrogen reduction of fine iron ore at low temperature, mixture endreduction in iron bath with carbon and hydrogen, trace elements separation from scrap, metallurgical theory, and modeling with multi-scales of time and scope, etc.

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    Progress in the Research of Phase Transformations in High Magnetic Field
    LI Chuan-jun, REN Zhong-ming
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 21-34.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2278)      PDF(pc) (3098KB)(2229)       Save

    Processing of materials in a high magnetic field has received much attention over the past decades. Phase transformations have a decisive effect on structures and properties of materials. Many studies have indicated that a magnetic field can change thermodynamics and kinetics of phase transformations and further modify microstructures, morphologies, compositions and performance. The article reviews development of phase transformations in a high magnetic field. Methods used to detect phase transformations are briefly described. The effect of a magnetic field on thermodynamics and kinetics of phase transformations in ferrous magnetic alloys is described. In addition, the thermal treatment and grain boundary engineering in a magnetic field are discussed. Studies on phase transformations and structural morphologies of non-magnetic materials in a magnetic field are surveyed.

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    Effect of Pulse Magnetic Field Annealing on Magnetic Properties of Grain-Oriented Silicon Steel
    LI Li-juan, LIU Li-hua, XIA Qiang-qiang, ZHAI Qi-jie
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 35-38.   DOI: 10.3969j.issn.1007-2861.2011
    Abstract2871)      PDF(pc) (1206KB)(1334)       Save

    We have carried out experiments of annealing by pulse magnetic field. The results show that a pulse magnetic field with intensity lower than 1 T can promote magnetic induction density (B8) of grain-oriented silicon steel, while the magnetic properties deteriorate sharply when intensity is higher than 1 T. It has also been found that heating by using pulse direct current can cause the magnetic properties to deteriorate, in contrast to the traditional heating using resistance furnace. Our research shows that pulse magnetic field annealing may become an effective method to modify material structures.

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    Set Partitioning in Hierarchical Trees Algorithm for Color Images Based on Multiwavelet
    CHEN Jun-li, QING Ding-hu, LI Xiang, WAN Wang-gen
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 39-43.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2034)      PDF(pc) (1184KB)(1183)       Save

    We proposes an improved color set partitioning in hierarchical trees (SPIHT) algorithm based on multiwavelet. The algorithm converts a RGB color image into the YCbCr format. Clearly, bits assigned to luminance Y plane are twice than that Cb and Cr chrominance planes. A new spatial orientation tree structure is developed between channel planes based on SPIHT coding. We embed multiwavelet SPIHT codes for color images with the re-combined multiwavelet coefficients. The results show that performance of the proposed coding method is superior to SPIHT on 9/7 wavelet.

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    Source Synchronized Clock Transmission Based on Inter-Packet Gap of Full-Duplex Ethernet
    CHEN Jian, ZHANG Jun-jie, SONG Ying-xiong
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 44-50.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2357)      PDF(pc) (2609KB)(1930)       Save

    A source synchronized clock transmission method is proposed based on inter-packet gap (IPG) of Ethernet running in a full-duplex mode. A synchronous residual time stamp (SRTS) is adopted as the clock transmission algorithm. The characteristic of the new method is immune to fluctuation for in-band Ethernet traffic. Parameters of the SRTS algorithm used in Ethernet IPG and the output jitter waveform of recovered clock are determined by using continued fraction. Simulation results and field programmable gate array (FPGA) implementation are given to demonstrate high quality of the recovered clock.

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    Experiment of Long-Haul Subcarrier Multiplexing Cable TV System Using Chirped Fiber Grating Dispersion Compensation
    SONG Ying-xiong, SONG Jian-gang, LIN Ru-jian, FAN Chun-hua
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 51-56.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2433)      PDF(pc) (2393KB)(1415)       Save

    We present experiment results of dispersion compensation using chirped fiber grating in 1 550 nm subcarrier multiplexing (SCM) long-haul cable TV (CATV) system. By placing the dispersion compensation module (DCM) at the theoretically optimal position, better composite second order distortion (CSO) is obtained. The test results of 200 km long-haul system with and without DCM show that chirped fiber grating DCM can improve the CSO performance. 

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    Image Colorization with Block Image Database and Texture Feature Points
    LU Dong-hui,ZHANG Chuang,WANG Shi-gang
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 57-63.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2191)      PDF(pc) (4653KB)(1567)       Save

    We propose a new method for image colorization to overcome problems including heavy computation load, poor quality, and excessive human intervention. We choose rectangular blocks from various color images using segmentation and clustering, and calculate color histograms and texture feature points of the blocks. We then build a database by comparing similarity of the blocks based on the color histograms, and find the best matching in terms of the Euclidean distance between the target grayscale blocks and the source color blocks. Having constructed databases of four kinds of image blocks, tree, sky, sand and grass, the target gray image can be colorized using the block database without human intervention.

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    Analysis and Design of Rectifying Circuit with Compact Structure and High Efficiency
    GAO Yan-yan,YANG Xue-xia,ZHOU Jian-yong
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 64-67.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2374)      PDF(pc) (1470KB)(2033)       Save

    A novel microstrip rectifying circuit is proposed in this paper. The rectifying circuit is analyzed and designed with the software ADS 2006A. Simulation results show that the rectifying circuit obtains 81.4% conversion efficiency from microwave to DC power on a load of 320 Ω at 5.80 GHz. The bandwidth of conversion efficiency more than 75% is 300 MHz. Experiment results indicate that the highest voltage of 4.57 V is measured on a load of 298 Ω with conversion efficiency of 68.5%. The rectifying circuit has advantages of compact structure, high conversion efficiency and ease of integration. It can be applied to energy supply for radio frequency identification (RFID) systems and wireless sensors.

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    Predicting Radio Wave Propagation Characteristics in Rectangular Tunnels
    JIA Ming-hua,ZHENG Guo-xin,ZHAO Xing,ZHANG Xin
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 68-73.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2149)      PDF(pc) (2336KB)(1261)       Save

    It is important to predict characteristics of radio wave propagation. The pathloss characteristic has close correlation with coverage and layout of a radio system. The timedelay characteristic determines the maximum transmission rate of a radio digital system. In this paper, a new model is presented to predict wave propagation in rectangular tunnels with a rectangular section. In an rectangular tunnel, paths between transmitter and receiver can be determined analytically using geometric optics. The method avoids complicated ray tracing calculation. From the simulation results, accuracy of the prediction is better than ray tracing. The less the separation between transmitter and receiver, the larger the root mean square (RMS) delay spread and mean excess delay. The larger the dimension of cross section, the larger the RMS delay spread and the mean excess delay. 

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    Parallel Grid Connected Inverters for Multiple Armature Winding Wind Power System without Grid Voltage Sensors
    TANG Yan-yan,RUAN Yi,YANG Yong
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 74-78.   DOI: 10.3969/j.issn.1007-2861.2011.
    Abstract2757)      PDF(pc) (1959KB)(1235)       Save

    The control strategy based on virtual power grid flux without power grid voltage sensors is proposed to improve reliability and reduce cost for the gridconnected inverter. A novel control strategy makes the DC voltage flexibly run in parallel based on multiple armaturewinding, making the system more reliable and robust. Experimental results show that output currents are sinusoidal, with a good dynamic and static performance. Thus feasibility of the control strategy is verified.

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    Prototype of Humanoid Facial Robot SHFR-1
    KE Xian-xin,TANG Wen-bin,CHEN Yu-liang,YANG Xiao-chen
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 79-84.   DOI: 1007-2861(2011)01-0079-06
    Abstract2135)      PDF(pc) (2345KB)(1468)       Save

    By analyzing the facial expression and motion of facial muscles, the mechanism and control systems of a facial robot are designed. The mechanism and motion of the corresponding virtual prototype are analyzed. A facial robot SHFR-1 is developed based on the results of the analysis. Experimental results of facial expressions show that SHFR-1 can express six basic expressions: happiness, sadness, surprise, fear, anger and disgust.

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    Design and Realization of Controller Area Network Bit Timing Processor
    HU Yue-li,XU Xiao-yong
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 85-89.   DOI: 10.3969/j.issn.1007-2861.2011.
    Abstract2185)      PDF(pc) (1859KB)(1395)       Save

     The way in which the bit timing of controller area network (CAN) bus communication is dealt with determines whether the CAN controller can receive or transmit data correctly. This paper presents a structure of nominal bit time and the principle of bit synchronization. We give an optimized method of nominal bit time of CAN〖KG*1/9〗2.0 protocol that the four nonoverlapping segments of traditional nominal bit time is simplified to 3 nonoverlapping segments. Based on this, we propose a design method for bit timing processor (BTP) of CAN bus on the synchronized state machine. We also provide programmable time segments to compensate for the propagation delay times and phase shifts, and show simulation and verification of the design. The results show that the design in line with the CAN 2.0 protocol can more easily deal with the CAN bus communication bit timing. Control of CAN bus protocol on the bit timing and bit synchronization is realized, which better optimizes the CAN network.

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    Self-Repairment of Wearing in Gear Transmission
    MO Yun-hui,ZHANG Li-ming,WANG Shuai-bao,TAO De-hua
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 90-93.   DOI: 10.3969/j.issn.1007-2861.2011.
    Abstract2050)      PDF(pc) (1492KB)(1327)       Save

    A type of selfrepairing lubricant containing Sn and Zn powder additives and suitable for steelsteel tribopair is developed. Its repairing and tribological properties are reviewed on a rebuilding model MS800 tester. The tooth contact stress of gear transmission is calculated with ANSYS. The findings showed that repairing coatings can be formed on steel surface because of the SnZn selfrepairing lubricant, which has good antifriction and antiwear properties under different loads. Simulation results indicate that tooth contact stress is reduced by 16.7% after repairing with the lubricant.

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    Notes on Solutions to Burgers Equation Hierarchies
    HU Liu-feng,ZHANG Da-jun
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 94-99.   DOI: 10.3969/j.issn.1007-2861.2011
    Abstract2171)      PDF(pc) (1727KB)(1397)       Save

    We consider exact solutions for the isospectral and nonisospectral Burgers hierarchies. The two hierarchies can be linearized through the ColeHopf transformation. Solutions are given using the technique for selecting Wronskian entries. Relationship between some solutions and their dynamic characteristics are investigated.

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    Influence of Packing Densities on Surface Stress of Gene Chip
    LI Jing-jing1,2,TAN Zou-qing1,QIN Wei3
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 100-102.   DOI: 10.3969/j.issn.1007-2861.2011.
    Abstract2708)      PDF(pc) (905KB)(1370)       Save

    Nanomechanical behavior of gene chip in labelfree biodetection is studied using the energy method.Considering electrostatic energy, hydration energy and configuration fluctuations of DNA layer as well as mechanical energy of chip, an energy formula is set up. The relation between curvature radius of the neutral axis and surface stress of gene chip is obtained according to the minimum principle of energy. Influence of packing densities on surface stress of gene chip is predicted. Theoretical predictions for surface stress of gene chip are compared with experimental data to validate the presented solutions.

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    Optimal Stopping for Image Smoothing Based on Kernel Density Estimation
    LI Yi,WANG Yuan-di
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (1): 103-110.   DOI: 10.3969/j.issn.1007-2861.2011.
    Abstract2326)      PDF(pc) (3216KB)(1766)       Save

    Optimal stopping has been an important issue in image smoothing based on partial differential equations. According to the independence of random variables and the kernel density estimation, a novel optimal stopping criterion is proposed, which can be used without knowing the noise variance. Numerical experiments show consistency between the results obtained with the proposed method and that of the mean square error (MSE) method. The criterion is applicable at various noise levels.

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    Optimization of Very Minimum Chirp Keying Modulation Waveforms to Eliminate Linear Spectrum
    WANG Jun,ZHENG Guo-xin,JIANG Jun-chao
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 111-114.   DOI: 10.3969/j.issn.1007-2861.2011.02.001
    Abstract2731)      PDF(pc) (1666KB)(1224)       Save

    Very minimum chirp keying (VMCK) is a highly efficient ultra-narrowband modulation technique, which has the advantage of narrow band occupancy, intensive sideband suppression, and higher data transmission efficiency. However, if we directly derive the analytical expression of its power spectrum from VMCK signal expression, the result is complex and imprecise because the result contains a non-integral function. Linear spectrum does not carry useful information. In order to obtain narrower bandwidth, stronger sideband suppression and better demodulation performance, we remove the harmonic spectral lines in power spectrum by separate sinusoidal basis fitting to optimize VMCK.

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    Power Allocation for Amplification-and-Forwarding Cooperative Communication
    SHI Hai, ZHOU Jian
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 115-118.  
    Abstract2186)      PDF(pc) (1009KB)(1067)       Save

    To solve the problem of power allocation for non-regenerative amplification-and-forwarding relaying communication systems with limited capacity, two power allocation schemes based on optimal capacity rule are proposed, called generous scheme and stingy scheme, respectively. The simulation results have shown that the proposed two power allocation schemes can improve system capacity with different degrees. 

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    Reconstruction of Spatial Hearing Based on Locally Linear Embedding
    SHANG Yong-Qing, FANG Yong, HUANG Jing-Hua
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 119-124.  
    Abstract2011)      PDF(pc) (1629KB)(1304)       Save

    In spatial hearing, mass data of head-related transfer function (HRTF) is a factor that greatly influences the synthesis of virtual sounds. To reduce the data used, we propose a spatial hearing reconstruction method based on locally linear embedding (LLE). Using LLE, high dimensionality is mapped to a lower dimensional dataset suitable for regressive analysis and classification. To classify by an unsupervised cluster method, a representative HRTF is extracted from all HRTFs. Other HRTFs can be reconstructed in spatial hearing from the representative HRTF with modified interpolation. Compared to the principal component analysis (PCA), the data with reduced dimension obtained by using LLE preserve more perceptive information. Relations among the HRTF data can be found, with which modified interpolation can be obtained and HRTF reconstruction error can be reduced. Simulation results show that the proposed method effectively reduces HRTF data. It is useful to improve efficiency of synthesis for virtual sound source in practical applications.

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    Localization of Multiple Sound Sources in Far Field Using Trijunctional Spherical Microphone Array
    ZHUANG Qi-Lei, HUANG Qing-Hua
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 125-131.  
    Abstract2098)      PDF(pc) (2334KB)(1668)       Save

    A trijunctional spherical microphone array is designed to sample the sound field. A multiple sound sources localization algorithm is realized by planewave decomposition in the three-dimensional spaces with this array. Experimental results show that, using 98-element trijunctional spherical microphone array to locate multiple far-field sound sources can improve the accuracy and spatial resolution of the sound source localization. In addition, this method is robust to the environmental noise.

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    Scattering Current Analysis of T-Shaped Wires with the Theory of Maxwellian Circuits
    WU Ming-Liang, CHEN Wen-Hui, XUE Chang-Wei, MEI Kenneth K.
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 132-137.  
    Abstract1963)      PDF(pc) (2272KB)(1182)       Save

    The scattering current of T-shaped wires is analyzed with the recently proposed theory of Maxwellian circuits (MC). The structure is equivalent to LC circuit, and the scattering currents can be worked out from the differential equations relevant to the circuit. In the numerical experiments, circuit parameters L,C,α,β and scattering currents of two T-shaped structures are calculated. The analysis shows that circuit parameters and scattering currents are not only in accordance with the physical concepts, but also agree with the results of the method of moments (MoM), and with those reported in the literature. Thus the described method is valid and efficient.

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    Simulation of Special Flight Effects Based on Particle System
    CHEN Jun-Li, XU Wei-Feng, HUANG Bing, WAN Wang-Gen
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 138-142.  
    Abstract1967)      PDF(pc) (1292KB)(1225)       Save

    This paper studies simulation of jet fire based on the particle system. Texture mapping and levels of detail (LOD) techniques are used to enhance the operation speed. The result shows that visual effect of jet fire is true to life. It can meet the needs of real time animation on ordinary PCs. Simulation of rain and snow is also presented.

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    A Novel Bandpass Filter Based on Coupling Matrix
    GAO Shan, XIAO Zhong-Yin, CHEN Wen-Feng
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 143-146.  
    Abstract2031)      PDF(pc) (1433KB)(1927)       Save

    A novel microstrip bandpass filter (BPF) with two transmission zeros is presented. This filter has a wide upper stopband by using two novel slow-wave resonators. With an “N+2” coupling matrix method, the filter is easy to design and has high frequency selectivity. Measured results show that the filter has good response performances including low insertion loss of 1.66 dB at the center frequency 2.4 GHz, and upper stopband frequency up to 7.0 GHz. These are in good agreement with simulation.

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    Optimal Velocity Function Considering Stopping Sight Distance
    SONG Tao-1, DONG Li-Yun-1, KUANG Hua-2, LI Xing-Li-3, DAI Shi-Qiang-1
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 147-152.  
    Abstract2279)      PDF(pc) (1582KB)(1427)       Save

    This paper deals with the optimal velocity function for traffic flow, characterized by a rational function form. The critical headway is taken as the control parameter and used to establish the non-concave fundamental diagram. A new optimal velocity function considering stopping sight distance is proposed to describe human driving behavior in the driver-vehicle-road environment by rescaling the critical headway. Compared with other classical optimal velocity functions and related fundamental diagrams, the new function has advantages in explaining real traffic features such as scattering density-dependent flow data and variable highway capacity.

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    Forms of Energy Release Rate and J Internal Increase Rate Based on Finite Deformation Theory
    SONG Yan-Qi-1, LV Yan-Wei-2
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 153-157.  
    Abstract2525)      PDF(pc) (776KB)(1917)       Save

    To study the crack propagation problem, a model in terms of incremental deformation represents the real propagation mechanism by taking instantaneous configuration as a reference. It requires an accurate definition of incremental deformation on a fresh crack. However, it is difficult to make the instantaneous configuration including zones around the crack tip satisfy the relevant equilibrium equations with regards to the initial configuration. Generally, energy methods such as crack tip energy release rate G and J-integral are powerful in analyzing and solving crack problems. Therefore the focus is on the determination of the form of the increase rate of energy release rate, ?, and that of J-integral, ?, regarding instantaneous configuration. Because the classical theory of small deformation takes initial configuration as a reference, the formulae for ? and ? are derived by using the energy principle and variational principle in the finite deformation theory in the present study. This work provides a new theoretical line for studying crack propagation.

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    Application of Preconditioning and Multi-grid Technique to Two-Dimensional Flow Calculation
    LIANG Zi-Xuan, DING Jue, WENG Pei-Fen
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 158-163.  
    Abstract2326)      PDF(pc) (1494KB)(1328)       Save

    Turkel preconditioning matrix and multi-grid technique are combined to develop an efficient method suitable for numerical computation of low-speed viscous flow. Rigidity of the system of compressible Navier-Stokes equations is improved using the Turkel preconditioning matrix, thus the compressible range of Mach of two-dimensional flow is extended for low-speed flows. By using the LU-SGS (lower-upper symmetric Gauss-Seidel) implicit method and introducing preconditioning methods together with a multigrid scheme, an RAE2822 airfoil is simulated at low Reynolds number and a small angle of attack. Numerical results show that the preconditioning methods and multi-grid technique can greatly improve convergence of viscous flows. Besides, the above method can extend the computational domain of Mach number of compressible Navier-Stokes equations to a low-speed incompressible area, which is effective in calculating low-speed viscous flows.

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    Isospin Dependent Properties of Asymmetric Nuclear Matter Using Gogny Interaction
    CHEN Rong-1, 2, YANG Yan-Fang-1, CHEN Lie-Wen-2
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 164-169.  
    Abstract2244)      PDF(pc) (1557KB)(1144)       Save

    Using the finite-range Gogny interaction, the equation of state (EOS) and the single-particle potential as well as their isospin dependence in isospin asymmetric nuclear matter is studied. By comparison with other models and empirical values, we show the limitation of the Gogny interactions D1, D1S and D1N, and necessity of a new parameterization of Gogny interaction.

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    Recording and Readout of Femtosecond Spectral Holography
    ZOU Hua, YAN Xiao-Na, HAN Feng, LIANG Ling-Liang
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 170-175.  
    Abstract1802)      PDF(pc) (1136KB)(1115)       Save

    Based on the recording and readout structures of femtosecond spectral holography, the entire physical procedures is depicted, and the mathematical expressions for the output pulse field distribution in different directions is given. The choices of the angles of signal, reference and test pulses, and distributions of the signal, reference and test pulses on the spectral plane are discussed. Then the influence of signal, reference and test pulses’ duration on the output pulses is discussed. The results are useful to the ultrashort pulse signal processing including shaping, storage and reconstruction.

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    Dispersion Characteristics of Femtosecond Pulse in Monopotassium Phosphate Crystal
    LIU Yan-Hong, WANG Yan, BAI Li-Hua, XU Jun, SONG Yi-Wen, PANG Wan-Wen, ZHANG Hui-Fang
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 176-181.  
    Abstract1854)      PDF(pc) (1751KB)(1348)       Save

    Based on the dispersion equation of principal-axis refraction index, regardless of crystal absorption and other nonlinear interactions, dispersion characteristics of femtosecond laser in monopotassium phosphate (KDP) crystal are studied. As a result of the crystal dispersion, light waves of different frequencies in the incident femtosecond laser pulse propagating in a crystal can result in different phase changes so that waveforms of resulting pulses are correspondingly changed. By numerical calculation, propagation properties of the input pulse in the crystal are obtained. It is found that the pulse width, intensity and expanding width of the output pulse depend on the crystal length, central wavelength and polarization direction of the input pulse. The results may be useful in frequency doubling, pulse shaping, development of optical crystal devices, etc.

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    Chebyshev-Collocation Spectral Method for Volterra Type Integro-Differential Equations
    WU Hua, ZHANG Jue
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 182-188.  
    Abstract2335)      PDF(pc) (741KB)(1715)       Save

    A Chebyshev-collocation spectral method is developed for Volterra type integro-differential equations. The Volterra type integro-differential equation as two linear integral equations of the second kind is rewrited, and the integrand with Lagrange basis functions and the Lagrange basis functions in terms of the Chebyshev polynomials are expanded. An error analysis is conducted based on the L norm. Numerical results are presented to demonstrate effectiveness of the proposed method.

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    Analysis of Disciplinarian of Sedimentation about Large Caliber Pipeline Buried in Complex Stress State Soil
    XU Xu-1, YAO Man-Xi-1, CHANG Ying-2
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 189-195.  
    Abstract2192)      PDF(pc) (3552KB)(1088)       Save

    To deal with the complex-stated problem of tunnel construction in the fifth building site of No.7 Metro Line in Shanghai, the sedimentation of large caliber conduit buried in complex soil caused by the surrounding soil gathered in the construction and second concretion is discussed. The current of sedimentation along the change of soil layer, range of disturbed soil layer, depth of conduit and change of the caliber about the large caliber conduit buried in complex soil is analyzed. This is done with the solution to non-completed concretion-girder and Lichi difference method. The juncture between two conduits to provide guidance to similar projects in which sedimentation about conduit bury in the soil is caused by concretion or second concretion of the soil is also analyzed. 

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    Cited: Baidu(2)
    Influence of Horizontal Reinforcement Forms on Strength of Sand Reinforced with Horizontal-Vertical Inclusions
    WEI Wei, ZHANG Meng-Xi, ZHANG Zhen-Lei
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 196-202.  
    Abstract1896)      PDF(pc) (2270KB)(1136)       Save

    More than 100 sets of plane stress tests were carried out on sand reinforced with horizontal-vertical (H-V) inclusions of perspex with different forms of horizontal inclusions (hole and coverage) and different height of vertical inclusions and cell pressure. Effects of the form of horizontal reinforcements on the strength of sands reinforced with horizontal-vertical inclusions were studied. The influence of height of vertical inclusions and confining pressures on strength is validated. The results show that strength of the form with hole is better than that of coverage because the axis load can be transferred to the lower soil, the vertical inclusions did not break earlier, and the form with hole has a cancellus effect which can improve the soil strength. The hole size has some influence on strength. It is verified that height of the vertical inclusion has an optimal value.

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    Cited: Baidu(3)
    Optimization of Steel Reinforced Concrete Composite Beam Based on Sequential Linear Programming Method
    ZHU Jie-Jiang, CHEN Ting-Jun
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 203-208.  
    Abstract1938)      PDF(pc) (1317KB)(1103)       Save

    Based on the improved move limit method of the theory of sequential linear programming (SLP), this paper develop a program applied to optimization of steel reinforced concrete composite and reinforced concrete beams. Practical examples indicate that the optimization method converges quickly and accurately. Besides, reinforced concrete beam is more economical than steel reinforced concrete composite beam without constraint on the height of beam section according to the comparison of their optimized results.

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    Cited: Baidu(6)
    Mechanical Behavior of Suzhou Clay
    SHEN Hai-E, SUN De-An, CHEN Bo
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 209-215.  
    Abstract2084)      PDF(pc) (1563KB)(1413)       Save

    A number of isotropic compression and consolidated-drained and undrained triaxial tests on undisturbed and reconstituted Suzhou clay have been carried out to study the compression and shear characteristics. The comparison of compression curves of undisturbed and reconstituted samples shows that the undisturbed samples have larger void ratio, compression index and swell index under the same confining pressure. The comparison of stress ratio-strain curves of undisturbed and reconstituted samples shows that the confining pressure has no effect on the reconstituted samples but has an effect on the undisturbed samples. In other words, the stress ratio is high with shearing at the low confining pressure. Also, strength of undisturbed samples is lower than the reconstituted samples when sheared under the same confining pressure. This behavior is caused by the difference in void ratio.

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    Failure Mechanism of Rock Materials Containing Double Closed Cracks under Uniaxial Compression
    SHAO Wei-1, CHEN You-Liang-1, ZHOU You-Cheng-1, LUO Ren-An-2
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (2): 216-220.  
    Abstract2104)      PDF(pc) (1155KB)(1184)       Save

    Uniaxial loading tests of rock specimens with double parallel inclined closed cracks were conducted on a micro-controlled electro-hydraulic uniaxial loading system. The analytical expression of stress intensity factor (SIF) is derived in this paper. The influence of surface friction coefficient of crack on the stress intensity factor of specimens is analyzed. The process is studied using the finite element method (FEM) method, and the results compared with the analytical solution. The results show that SIF decreases with the increase of surface friction coefficient of crack. It is feasible to use FEM to solve stress intensity factor and the safety of containing crack component can be accurately predicted. In addition, the failure macro-mechanism of specimens is discussed.

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    Cited: Baidu(5)
    Analysis of Very Minimum Chirp Keying Signals with Continuous Phase Modulation Characteristics
    JIANG Jun-Chao, ZHENG Guo-Shen, QIU Zhi-Yi, LIU Ya-Jun
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (3): 221-226.   DOI: 10.3969/j.issn.1007-2861.2011.03.001
    Abstract2825)      PDF(pc) (1584KB)(1186)       Save
    The very minimum chirp keying (VMCK) modulation possesses characteristics of an ultra narrow band (UNB). This paper uses a general analysis method of continuous phase modulation (CPM) to select a linear signal as the integral pulse, give the continual phase modulation express of VMCK, and construct a new kind of the VMCK transmitter structure. The normalization power spectral density formula of VMCK is then derived, with the power percentage bandwidth as an inspection criterion. It is proven that, for an orthogonal binary signal set, VMCK has a narrower main lobe compared with the minimum shift keying (MSK) modulation. Therefore better band width efficiency can be achieved with VMCK.
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    Cited: Baidu(2)
    Caplanar Stripline Fed Triple-Band High-Gain Microstrip Antenna
    ZHOU Jun, YANG Xue-Xia, LV Yan-Jing
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (3): 227-231.   DOI: 10.3969/j.issn.1007-2861.2011.03.002
    Abstract3068)      PDF(pc) (2368KB)(1529)       Save
    A microstrip antenna fed by a coplanar stripline (CPS) working at 2.4, 3.5 and 5.8 GHz with a simple structure and a high gain is proposed. Multifrequency operation is realized by introducing a pair of small hoops in the center of the rhombic structure. The gain is improved by placing a metal reflector beneath the substrate. A CPS to microstrip Balun is designed for measurements and more applications. The measuring results agree well with simulation, which meet the demand of practical applications. Gains of all operating frequencies are higher than 10 dB.
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    Cited: Baidu(5)
    Dynamic Markov Chain Monte Carlo Detection Based on Multiple Input- Multiple Output Orthogonal Frequency Division Multiplexing Systems
    YANG Hui-Lian, YANG Jian-Guo, SHI Hai
    Journal of Shanghai University(Natural Science Edition)    2011, 17 (3): 232-237.   DOI: 10.3969/j.issn.1007-2861.2011.03.003
    Abstract2444)      PDF(pc) (1397KB)(1009)       Save
    In multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems, the Bayesian multiuser detection scheme based on the Markov chain Monte Carlo (MCMC) method has good performance in suppressing multipath fading, carrier frequency offset and phase noise. The algorithm, however, cannot find its application in real-time due to a low convergence rate. To solve this problem, we propose a new method called dynamic MCMC detection. Correlation between samples of the system state and the threshold decided on convergence are used to dynamically select the convergence region about the samples of the system state in an iterative operation. This improves capability of real time operations and maintains the performance of the algorithm. Simulation results show that the proposed method has a higher convergence rate and lower bit error rate.
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