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15 February 2007, Volume 28 Issue 2 Previous Issue    Next Issue
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Tracking control of chaos in singular biological economy systems Zhang, Yue (1); Zhang, Qing-Ling (1); Zhao, Li-Chun (2); Liu, Pei-Yong (1) 2007, 28 (2):  157-160+164.  DOI: - Abstract ( 280 )   HTML   PDF (434KB) ( 1072 )   Discusses the problems of chaos and its control of a class of singular biological economy system by the theory of differential-algebraic equations. Judged by the numerical method, the system presents complicated dynamical characteristic hence the chaotic phenomenon along with the change of the seasonal influencing factors on it. Then, a controller is designed by use of feedback linearization to cause the output of chaos system to track an expected constant value or period orbit with a rational developing strategy formulated, thus implementing the feedback tracking control of chaos in the system. Numerical simulations are given to illustrate that the control method is effective in practice and enables the biological population in chaotic states to grow smoothly and offer mankind material wealth for long. References | Related Articles | Metrics

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Text region localization using wavelet transform in combination with support vector machine Sun, Hong-Xing (1); Zhao, Nan-Nan (2); Xu, Xin-He (1) 2007, 28 (2):  165-168.  DOI: - Abstract ( 267 )   HTML   PDF (493KB) ( 821 )   A method based on wavelet transform in combination with support vector machine (SVM) is proposed for localizing text region. After the image was decomposed by wavelet transform, SVM is used to extract the texture characteristics of text from the low-frequency vague image sub-space and high-frequency energy sub-space and determine what the current pixel belongs to, i.e., the text class or non-text class. Then, because there are possible noise and false text after SVM classification, the methods of morphological denoising and textural energy calculating are used to reprocess the results of SVM classification. The proposed method utilizes the characteristic that SVM suits high-dimension space so as to improve the efficiency of extracting text in addition to reducing the number of spatial sample inputs. Experimental results showed that the method can rapidly and effectively localize the text region in digital image. References | Related Articles | Metrics

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Application of neural network to project evaluation Hu, Qing-He (1); Zhang, Shuang (1); Wang, Ding-Wei (1) 2007, 28 (2):  169-171.  DOI: - Abstract ( 261 )   HTML   PDF (270KB) ( 501 )   Project evaluation is an important strategy for enterprises. Because of the significantly increasing cost and keen market competition, project evaluation will decide whether a firm succeeds or not in business, including opportunity seizing, cost control and competitive power. Studies the project's attributes influencing factors and explicit indexes, which affect the project value, and the relationship between them. The artificial neural network is used to develop a project value model, and the conventional BP algorithm is improved to get weighting factors for sample monitoring and training, thus determining the project value and assisting the decisionmaker to evaluate the project. A real application example is given to prove the efficiency of the algorithm and practicality of the model. References | Related Articles | Metrics

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e_ScopeWork: A flexible workflow system based on web service Wang, Guang-Qi (1); Zhang, Yu (1); Yu, Ge (1) 2007, 28 (2):  180-183.  DOI: - Abstract ( 229 )   HTML   PDF (271KB) ( 524 )   In the large-scale business environment, a business process may involve lots of different web services arising from one or several enterprises. To handle those business processes efficiently, the architecture of a flexible workflow management system, i.e., e_ScopeWork is proposed on the basis of web service. The functions of its components are studied to analyze the features of task scheduling in workflow. As a result, the scheduling approach, deployment, and implementation mechanism of tasks or task managers are discussed in detail, thus attaining the goal that a workflow can be deployed flexibly according to the requirements and scale of a business process. References | Related Articles | Metrics

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SUA-based algorithm for finding SATRs in DNA sequence Wang, Di (1); Zhao, Yi (1); Chen, Bai-Chen (1); Wang, Guo-Ren (1) 2007, 28 (2):  184-188.  DOI: - Abstract ( 177 )   HTML   PDF (341KB) ( 903 )   Studies finding approximate repetitions in DNA sequence, which is an important problem in gene analysis. Analyzing the approximate repetitions and similarity measurements and based on Hamming Distance, two definitions of pattern-similarity and segment-similarity are proposed as new measurements of similarity, then on the basis of the two definitions, a new concept of approximate repetition, i.e., the segment-similarity based approximate tandem repeats (SATR) is given. In addition, the succeeding unit array (SUA) as a lightweight index is introduced in finding SATRs in DNA sequence with an algorithm designed to find SATRs based on the index. Theoretical analysis and experiment results both show that the SATR finding algorithm based on SUA is superior to other methods in finding results and time saving. References | Related Articles | Metrics

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Simulation-based analysis of mathematic model of hydroturbine governor and its improvement Zhou, Yan (1); Li, Hai-Cheng (2); Zhao, Hai (1); Zou, Yong (1) 2007, 28 (2):  189-192.  DOI: - Abstract ( 349 )   HTML   PDF (1164KB) ( 572 )   In hydroelectrical simulation the key model is that of hydroturbine governor. Discussing the way to develop the nonlinear mathematic model of the governor in the hydroelectrical simulation system and improve it, the phased analyzing/fitting method is introduced in modeling process to deduce the mathematical models of governor start-up and load rejection so as to solve the problems of overspeed starting and nonconvergent vibration during load rejection. According to the performance evaluation of the version 2.0/3.0 of the hydroelectric simulation system, the model developed is proved superior to the conventional one and running well during the simulation done in Fengman Hydropower Station. References | Related Articles | Metrics

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Digital watermarking algorithm based on wavelet for images Chen, Dong-Ming (1); Zhu, Zhi-Liang (1); Jiang, Hui-Yan (2); Chang, Gui-Ran (2) 2007, 28 (2):  193-196.  DOI: - Abstract ( 283 )   HTML   PDF (331KB) ( 511 )   A new digital watermarking algorithm based on wavelet was proposed for images. In the algorithm the two kinds of orthogonal watermarkings, i.e., robustness and reference watermarkings, are added to the wavelet coefficients of carrier images simultaneously after discrete wavelet transform (DWT) and then the images with watermarkings are obtained by inverse discrete wavelet transform (IDWT). The extracted reference watermarkings are used to estimate the attacks on the images so as to estimate further the original robustness watermarkings, since the attacks on both extracted robustness and reference watermarkings are the same. Test results showed the good sensitivity and robustness of the algorithm for the best-known attacks such as noise interference, filtration, image compression/clipping and other image processing actions. References | Related Articles | Metrics

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Simulation on performance of rake receiver with neural network-based combiner Sha, Yi (1); Wang, Bin (1); Liu, Xiao-Ye (1); Wang, Guang-Xing (1) 2007, 28 (2):  197-200.  DOI: - Abstract ( 247 )   HTML   PDF (318KB) ( 680 )   Linear combination technique for conventional Rake receiver is inadaptable to the nonlinear characteristics of wireless channel. So, the NN (neural network)-based combination technique is studied, which introduces the NN model with multilayer perception to determine model structure through simulation. Under different simulation conditions, the performance of Rake receiver using the equal gain, maximum ratio or NN-based combination technique was simulated separately. Simulation results indicated that the performance of Rake receiver with NN-based combiner is slightly better than that of conventional Rake receiver in ideal channel but obviously better in complicated channel environment. References | Related Articles | Metrics

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Near-liquidus electromagnetic casting of ZL201 alloy and thixoforming Wang, Ping (1); Zheng, Lian-Hui (1); Liu, Xiao-Tao (1); Cui, Jian-Zhong (1) 2007, 28 (2):  205-208.  DOI: - Abstract ( 181 )   HTML   PDF (496KB) ( 799 )   The as-cast microstructure of ZL201 alloy prepared by near-liquidus electromagnetic casting (NLEMC) was studied by means of electron microscope and image analyzer, and the mechanical properties of the alloy parts thixoformed were given through tests. The results showed that the semi-solid ZL201 alloy ingot prepared by NLEMC shows fine and homogeneous equiaxed grain structure and its average-equivalent-circle grain diameter is 48.8 μm, with the hardness of thixoformed parts 116.2 HV and tensile strength 308 MPa. All these indicated that both the as-cast microstructure of ZL201 alloy and mechanical properties of its thixoformed parts prepared by NLEMC process are superior to those of the alloy prepared by either electromagnetic casting or near-liquidus casting. The mechanism of grain refinement of as-cast ZL201 alloy prepared by NLEMC was discussed. References | Related Articles | Metrics

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Calculating thermodynamic properties of Si-Ca-Ba ternary alloy melts Li, Yang (1); Jiang, Zhou-Hua (1); Liu, Yang (1) 2007, 28 (2):  229-232.  DOI: - Abstract ( 278 )   HTML   PDF (332KB) ( 556 )   Based on the Miedema formation heat model for binary alloy and the Toop asymmetric geometrical model, the excess free energy, formation heat, excess entropy and the interactive coefficients of activity among all components of Si-Ca-Ba ternary alloy melts were calculated thermodynamically at 1873 K. The results showed that their values are all negative, and the thermodynamic properties of the ternary alloy tend to change obviously in the zone where the Si content is high or low. The minimum values of excess free energy, formation heat and excess entropy are all found at the point where the composition shows xSi=55%, xCa=45% and xBa=0. Adding barium to Si-Ca-Ba alloy melt does not affect obviously the excess free energy, formation heat and excess entropy, and such thermodynamic properties don't change greatly with the increasing addition of barium. References | Related Articles | Metrics

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Volatilization of MgO from ludwigite in carbothermal reduction process Liu, Ran (1); Xue, Xiang-Xin (1); Jiang, Tao (1); Wang, Xing-Juan (2) 2007, 28 (2):  233-236.  DOI: - Abstract ( 280 )   HTML   PDF (340KB) ( 550 )   Thermodynamic analysis was made to study the reduction volatilization of MgO in ludwigite by way of carbothermal reduction. The experimental results showed that the total mass loss rate of samples increases with rising temperature, of which the maximum is 61.8 wt% in the range from 1400°C to 1450°C. Magnesia in ludwigite was reduced and volatilized as gaseous magnesium vapour in the process of carbothermal reduction, and its mass loss rate went up to 98.0%. Magnesium was reoxidated into magnesia in the process of volatilization, where part of the volatilized matter formed the white feather-like crystal deposited on the bottom of furnace tube and the rest formed white powder deposited at the opening of furnace tube and adhered to tube wall together with boride/silicon volatilized. It was proved that there is volatilization of MgO from ludwigite in the process of carbothermal reduction. References | Related Articles | Metrics

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Effect of rolling schedule on plasticity of closed-cell aluminum foam Zu, Guo-Yin (1); Yao, Guang-Chun (1); Li, Hong-Bin (1) 2007, 28 (2):  237-240.  DOI: - Abstract ( 210 )   HTML   PDF (950KB) ( 507 )   The rolling process of closed-cell aluminum foam that was prepared by melt-foaming process was studied, as well as its deformation and failure behavior due to different pass reduction. Then, the main influencing factors on the roll ability of aluminum foam was discussed. The results showed that in the rolling process of closed-cell aluminum foam the basic principle is multiple pass with small deformation, e g., when the pass reduction is 0.1 mm, the 11 mm-thick aluminum foam in which the Si content is 12wt% can be deformed by 1 mm finally. When the pass reduction is too big, the failure of aluminum foam is typically in form of brittle fracture. The pass reduction taken should be proper for the excellent energy-absorbing characteristic of aluminum foam, but the very small deformation will be easy to lead the rolled piece to be bent then shear failure finally. The way to improve the roll ability of aluminum foam is to decrease its Si content and ensure the homogeneity of its microstructure and mechanical properties and especially adopt proper pass reduction with low rolling speed. References | Related Articles | Metrics

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Differential-quadrature method to analyze vertical dynamic characteristics of submarine fluid conveying pipeline Bao, Ri-Dong (1); Wen, Bang-Chun (1); Gong, Bin (2) 2007, 28 (2):  241-245.  DOI: - Abstract ( 261 )   HTML   PDF (502KB) ( 825 )   Under the hostile submarine conditions, the dynamic characteristics of a submarine fluid conveying pipeline in a suspended span is quiet different from those of a pipeline on land, which was affected by the coupling effect of the flows inside and outside the pipeline. An attempt is made to use the differential-quadrature method (DQM) to solve the vertical vibration of the pipeline, with the influence of both the inside and outside parameters on the vertical vibration taken into account, such as the flowrate and fluid pressure inside the pipeline, the flowrate and damping outside the pipeline and axial force. The dynamical characteristics and how the permitted suspended span varies with the flowrate inside and outside the pipeline, axial force and fluid pressure inside the pipeline were calculated and analyzed. The results indicated that DQM is successful to the analyses of dynamical characteristics of the pipeline suspended span and its fatigue and reliability design. References | Related Articles | Metrics

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Geometrical nonlinear characteristic analysis of giant magnetostrictive actuator Yuan, Hui-Qun (1); Li, Dong (1); Sun, Hua-Gang (1) 2007, 28 (2):  246-249.  DOI: - Abstract ( 263 )   HTML   PDF (416KB) ( 522 )   Considering the nonlinear rigid characteristic of the reed in the giant magnetostrictive actuator, a composite nonlinear model was developed involving the characteristics of square and cube values of reed's damping. Then, the analytic solution of the geometrical nonlinear vibration system and the frequency-response properties of the actuator were analyzed by using multi-scale method. Based on the model, the numeric and academic solutions with cutting case and without cutting case are calculated, and the time domain waveform of the numeric and academic solutions are analyzed and compared, and the frequency-response relationship formulate with actual parameter are derived. And the effects of electromagnetic parameters f, piezomagnetic coefficient d33 and magnetic conductivity μ33T on frequency-response properties of the actuator are discussed. The results indicate that the time domain waveforms showed by analytic and numerical solutions are about the same and both can meet the practical requirements, the parameters f, d33 and μ33T all affect obviously the frequency-response characteristic of giant magnetostrictive actuator, which must be taken into account when studying its nonlinear rigidity. References | Related Articles | Metrics

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Development of virtual measuring instrument for axis straightness error Chen, Li-Jie (1); Tian, Wen-Yuan (1); Zhang, Lei (1) 2007, 28 (2):  250-253.  DOI: - Abstract ( 239 )   HTML   PDF (992KB) ( 532 )   The measuring instrument was developed on the latest software platform LabWindows/CVI supplied by an American company, i.e., the National Instruments, with the data acquisition card and existing lab apparatus used as hardware platform. The virtual measuring instrument combines the technology to measure the form position error with virtual instrument to evaluate the axis straightness error by least square method and minimum zone estimation. Then, the image of axis straightness error is able to display on screen visually, thus analyzing the cause of axis straightness error. The measuring instrument has the advantages of high accuracy, reliable and stable operation and low cost, especially the excellent function expandability. It is available to lab teaching and industrial applications. References | Related Articles | Metrics

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Hydraulic testing study on artificial specimens with different pore proportioning Yu, Qing-Lei (1); Yang, Tian-Hong (1); Tang, Chun-An (1); Tham, L.G. (3) 2007, 28 (2):  258-261.  DOI: - Abstract ( 172 )   HTML   PDF (450KB) ( 476 )   The stress-strain-permeability behavior of artificial specimens with different pore proportioning was investigated electrohydraulically by servo-controlled MTS 815 rock test system. The influences of pore proportioning, porosity and seepage on rigidity and peak strength of artificial specimens were systematically studied by comparing testing results. The relationship between pore proportioning, porosity and permeability was thus obtained to set up an equation expressing how the hydraulic pressure and porosity weaken the rigidity and peak strength of artificial specimens. A reference was therefore provided to describe quantitatively the relationship between rock's porosity, permeability and peak strength. Experimental results showed that the coarse particles in proportioning and macro pore affect obviously the porosity and initial permeability and water weakens the rigidity and strength of specimens more significantly with increasing porosity. References | Related Articles | Metrics

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Monitoring and measuring of expressway tunnel and its structural reliability analysis Wang, Xiao-Ming (1); Liu, Bin (1) 2007, 28 (2):  270-273.  DOI: - Abstract ( 264 )   HTML   PDF (821KB) ( 622 )   Discusses the problems of the reliability analysis for tunnel structure by way of conventional stress field. Describes how the supersonic technique and geologic radar worked to detect/evaluate the concrete lining thickness and quality of an expressway tunnel. Based on the monitoring/measuring data obtained from a tunnel in service in Northeast China, a new way was proposed to evaluate comprehensively its structural reliability. The results showed that this method is highly practical and available to use for other road tunnels, and it is feasibly adaptable to lengthening the service life of road tunnels and reducing the costs for structural maintenance/reinforcement. References | Related Articles | Metrics

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Optimal control model to linked-together selling with bilevel inventory in regional distribution system Zhang, Chuan (1); Pan, De-Hui (1) 2007, 28 (2):  282-285.  DOI: - Abstract ( 223 )   HTML   PDF (166KB) ( 809 )   Studies a regional distribution system composed of a distribution center and multiple retailers among whom each plans its own demand in a fixed replenishment interval as a random variable obeying a certain probability distribution and is able to determine independently its optimal replenish-up-to level. In such a case the distribution center shall replenish the retailer's inventories circularly and periodically, and its fixed period is the same to the fixed replenishment interval as the retailers planned. Either the uniform distribution or Poisson distribution is taken into account for retailers' demand in a certain replenishment interval, and the retailer's customer demand is assumed to take place evenly. The control policies are thus schemed out to both retailer's optimal replenish-up-to level and distribution center's inventory. Finally, the effectiveness of the model is illustrated with a practical example. References | Related Articles | Metrics

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Method for multiple attribute decision making based on incomplete complementary judgment matrix Zhang, Yao (1); Fan, Zhi-Ping (1) 2007, 28 (2):  289-292.  DOI: - Abstract ( 282 )   HTML   PDF (151KB) ( 472 )   With respect to the multiple attribute decision making problem with fuzzy preference relations on alternatives in form of incomplete complementary judgment matrix, a method is proposed to analyze the decision problem. The multiple attribute decision making problem is introduced and an optimization model is developed on the basis of incomplete complementary judgment matrix provided by the decision maker and the decision matrix to determine attribute weights by Lagrange multiplier method. Then the appraisal values of all alternatives are calculated to rank them. A numerical example is given to illustrate the feasibility and practicality of the proposed method. References | Related Articles | Metrics

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Synthesis and bioactivity of novel acrylate derivatives Yang, Gui-Qiu (1); Sun, Ting (1); Yu, Xiu-Lan (2) 2007, 28 (2):  297-300.  DOI: - Abstract ( 180 )   HTML   PDF (256KB) ( 934 )   Three novel 2-((4, 4-dimethyl-3-oxoisoxazolidin-2-yl)methyl)-3-aryl acrylate derivatives were designed and synthesized utilizing Baylis-Hillman adducts as starting materials, based on the Clomazone (FMC-57020) [2-(2-chlorobenzyl)-4, 4-dimethylisoxazolidin-3-one] which is a low-toxicity high-efficiency soybean herbicide developed by FMC Corporation in the USA. The structures of the compounds were confirmed by IR, 1H NMR and elemental analysis. An evaluation done for their biological activities indicated that the target compounds 3 exhibit efficiently the herbicidal activity at 2000 g ai/hm2, while the intermediate ethyl 2-(bromomethyl)-3-(2, 4-dichloro phenyl) acrylate (2 b) shows insecticidal activity with a thorough control of tetranychus cinnabarinus at 600 g ai/hm2. Because of the herbicidal activities found in all the acrylate derivatives (3), they may be regarded as the lead herbicidal compounds to study further. References | Related Articles | Metrics