Table of Content

25 February 2009, Volume 37 Issue 2

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Mechanical Engineering

Effect of Time Characteristics of Software NC Real-Time Tasks on Manufacturing Accuracy

Li Di Wan Jia-fu Ye Feng Lai Yi-zong

2009, 37(2):  1-6. 

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In order to reveal the relationship between the uncertainty of software numerical control （NC） real-time tasks and the manufacturing accuracy, a model-based analysis method of mismachining tolerance is presented. First, the relevant theories concerning the sampling jitter, the input-output jitter, the NC task schedulability and the mismachining tolerance evaluation are analyzed. Then, a two-axis NC simulation model is established. Finally, some simulations are performed to reveal the relationships between the mismachining tolerance and the factors such as task jitter, task non-schedulability and aperiodic real-time tasks. The results show that the mismachining tole- rance respectively reaches 4.7% and 1.2% when the sampling jitter time and the input-output jitter time are both 80% of the task period, and that the tolerance is up to 13.4% when 40% of jobs fail to meet their deadlines. It is thus concluded that non-schedulable jobs may result in a noticeable mismachining tolerance.

Detection and Characteristics of Heating Resistance of Cutting Zone in Electric Hot Machining

Zhao Xue-zhi Ye Bang-yan Chen Tong-jian

2009, 37(2):  7-13. 

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This paper defines the structure and zone of heating resistance in electric hot machining, and proposes an accurate detection method of heating resistance according to the characteristics of heating circuit, by which the influences of circuit inductance and cable resistance can be effectively eliminated. Then, the effects of cutting depth, feed and speed on the heating resistance are experimentally investigated, and an experiential formula is de- duced. Moreover, based on the relationship between the heating resistance and the cutting condition, the effect of cutting condition on the heating power is analyzed, and a method of cutting condition determination according to the heating resistance is proposed. Thus, the heating current can be automatically adjusted. The effectiveness of the proposed method is finally verified by experiments.

Knowledge-Based Calculation and Prediction of Energy Consumption in Product Manufacturing Process

Gong Yun-qi Lu Min Wang Gang Fu Yi-li

2009, 37(2):  14-19. 

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To estimate the energy consumption in the manufacturing process of a new product, a knowledge-based prediction method is proposed in this paper. In this method, first, the ontology technology is used to explicate the calculation and management of energy consumption, and a semantic model of energy consumption knowledge and its semantic representation are proposed. Then, a case retrieval process and a method of ease result reuse are presen- ted in view of the characteristics of energy consumption. Moreover, an energy consumption prediction model corre- sponding to manufacturing parameters is established by means of neural network. The effectiveness of the model is finally verified by the machining process of a blade. Thus, a hierarchical framework of energy consumption predic- tion from the overall view to the technical process and further to the machining precedure is formed. The develop- ment and application of the corresponding prototype system are also illustrated in the paper.

Task Scheduling of Virtual Enterprise Based on Multi-Agent Technology

Zhao Qiang Xiao Ren-bin

2009, 37(2):  20-24. 

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In this paper, an operation model of task scheduling in virtual enterprises （VEs）, which consists of the management agent, the task agent and the resource agent, is established based on the multi-agent technology. In order to optimize the task scheduling, the production tasks of each resource agent in a VE are taken as the research objectives, the production tasks that have been determined for each resource agent, as well as the operation time and transportation time for the production tasks, are taken into consideration, and an optimal scheduling model for minimizing the manufacturing duration is proposed. The model is then solved by using a particle swarm optimization algorithm. The effectiveness of the proposed model and the algorithm is finally verified by the manufacturing practice of an industrial manipulator.

Nonlinear Twist Vibration of Main Transmission System of Vertical Medium Plate Mill

Meng Ling-qi Wang Jian-xun Wu Hao-liang Lei Ming-fie

2009, 37(2):  25-28,34. 

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According to the testing parameters of a 4200 vertical mill and by using the numerical calculation com- bined with theoretical analysis, this paper proposes a nonlinear vibration model with four degrees of freedom for the main transmission system of the vertical medium plate mill. The model is simplified and is then used to obtain the responses of the linear vibration system. The numerical solutions to the nonlinear vibration equations are obtained by means of Matlab. Afterwards, the motion state of the vibration system with a vibrating angular frequency approaching to the natural one is analyzed by means of phase graph, Poincare mapping graph and time＇history curve. Finally, the motion state of the system with a vibrating angular frequency varying in the natural frequency range is analyzed to further reveal the system stability. The results indicate that, when the angular frequency increases from the first-order natural frequency, the system is instable, with a motion state changing from a periodical mode to a quasi-periodical and even a chaotic one

Effect of Milling Cutter Parameters on Milling Stability of Thin-Wall Parts

Tang Ai-jun Liu Zhan-qiang

2009, 37(2):  29-34. 

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By analyzing the geometrical relationship of oblique cutting, the relationship between the oblique cutting parameters and the milling force coefficients is formulized, and the mathematical expressions describing the relation- ship between the cutter parameters and the cutting chatter are theoretically deduced. Moreover, the effects of helix angle and normal rake angle on the milling stability in the same milling parameter conditions are investigated, and the three-dimension stability graphs of the axial cutting depth, the radial cutting depth and the spindle speed are plotted. It is found from the stability graphs that the milling stability improves with the increase of the helix angle and the normal rake angle.

Modeling and Numerical Calculation of Asymmetrical Giant Magneto-Impedance Effect of Ribbons

Chai Xiu-li Zeng De-chang Liu Gui-xiong Yu Hong-ya Zhong Xi-chun Liu Wen-jie

2009, 37(2):  35-39,44. 

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Although the asymmetric giant magneto-impedance effect （AGMIE） is of high-sensitivity magnetic re- sponse, its sensing modeling in a ribbon with inner amorphous and outer crystalline layers still remains a complicated issue. To solve the problem, this paper establishes a model of AGMIE. In this model, the coupling between the crystalline and amorphous layers is described using the effective bias field, the diagonal and off-diagonal voltages are calculated by simultaneously solving Landau-Lifshitz kinetic equations and linear Maxwell equations, and the positive and negative working spaces of the magnetic field as well as the sensitivity of the sensor at various crystal- line layer thicknesses are thus deduced. The calculated results basically accord with the experimental ones, indica- ting that the proposed model is credible and effective.

Control System of Micro-Arc Oxidation Inverter Power Supply

Zeng Min Chen Xiao-hong Cao Biao Jiang Wei Liu Fang Wang Xiao-dong

2009, 37(2):  40-44. 

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To meet the requirements of micro-arc oxidation, this paper presents a two-stage inverter power supply and introduces its control system. In the proposed control system, a high-performance DSP is used as the control core, and the anterior power and the latter chopper inverter circuits are respectively driven by adjusting two groups of Pulse-Width Modulation （PWM） signals in four lines. The voltage regulation of the power supply is implemented by adopting a limited bipolar control mode in the power converter circuit, and various voltage waveforms are ob- tained by controlling the chopper inverter circuit. Moreover, the proposed control system is of some fault diagnosis and protection functions, such as overcurrent, overvohage-undervoltage, overtemperature and parameter overrun. Experimental results show that this system controls the power supply precisely and steadily and that it improves the adaptability of the power supply.

Quality Prediction and Control of Piston Rings Nitriding Based on Wavelet Transform and Elman Neural Network

Yang Jie Liu Gui-xiong

2009, 37(2):  45-48. 

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This paper aims to overcome the difficulty in the modelling of nitride hardening of piston rings. In the in- vestigation, the feature parameters of nitridation process are extracted using the principal component analysis method to reduce the dimension of input samples in the quality model. Then, a quality prediction model of the key process for piston ring manufacturing is built based on the wavelet Elman neural network. The proposed model helps to pre- dict the process quality fluctuation and lays a foundation for further process optimization and quality improvement. Experimental results show that the proposed method effectively improves the quality control of nitride hardening, and that the proposed prediction model predicts more accurately and converges more quickly than the normal Elman neural network, showing an accuracy of output-quality characteristic value of 89%.

Optimization of Process Parameters of Powder Injection Molding Based on Numerical Simulation

Zheng Zhen-xing Xia Wei Zhou Zhao-yao

2009, 37(2):  49-53. 

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Based on the CAE technology for powder injection molding and the fractional factorial design method, the injection process was numerically simulated by using the Moldflow software to forecast the effects of the process parameters and their pairwise interactions on the blank quality. According to the simulated results, the relationships among the temperature, the pressure, the filling speed and the time were investigated using a FC-80 injection mol- ding machine, and an optimal combination of process parameters was thus determined. The results indicate that （1） there exist strong pairwise interactions among the process parameters, which affect the product more greatly than a single factor; （2） the optimal combination of process parameters obtained by experiments accord well with the simulated one; and （3） the CAE technology in combination with experiments helps to optimize the process parameters and improve the product quality without repeated analyses.

Application of Graph Theory to Identification Algorithm of Kinematic Chain in Mechanical System

Yuan Qing-ke Li Wei-guang Liu Da-hui Zhang Ming-tian

2009, 37(2):  54-59. 

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By introducing the graph theory in the analysis of mechanical systems, this paper considers a mechanism as a network system of graph theory, employs the graph knowledge to describe the topology pattern and structure of a mechanism. Then, according to the characteristics of the constrained motion of a mechanism, a description method of the topology network is explored, the new concepts of incidence matrix and circuit matrix of the mechanism di- graph are put forward, an automatic computer identification algorithm of the kinematic chain of a mechanism is pro- posed, and on this base the motion equations of mechanical systems can be rapidly established for computer-aided analysis. The research results have been successfully applied to the development of a programmed software MSCAA （ mechanical-system computer-aided analysis）.

Vibration Characteristics of Planetary Transmission System with Compound Steel/Plastic Gears

Duan Fu-hai Hu Qing-chun Li Yu-ling

2009, 37(2):  60-64. 

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In order to reveal the vibration characteristics of the steel planetary transmission system with plastic gears substituting for the steel ones, this paper establishes the dynamic and experimental models of the transmission sys- tem and performs both theoretical analyses and experimental investigation of the vibration characteristics of four transmission systems in different steel/plastic compound modes. Then, the effect of the compound mode on the vi- bration characteristics is discussed. Numerical and experimental results demonstrate that plastic gears dramatically change the vibration characteristics of planetary transmission systems, greatly reduce the dynamic mesh loads on the sun-planet and ring-planet gears, and effectively suppress the gear-meshing sideband vibration and the high-fre- quency vibration of the transmission system. Moreover, it is indicated that the compound mode affects the vibration characteristics significantly, and that a reasonable steel/plastic gear compound may greatly reduce the dynamic mesh load and further reduce the vibration as well as the noise of the transmission system.

Traffic & Transportation Engineering

Underground Expressway Network Planning Based on Depot Choice Model

Hu Yu-cong Situ Bing-qiang Jin Wen-zhou Wang Xuan

2009, 37(2):  65-69. 

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According to the characteristics, planning principle and function orientation of the underground express- way serving middle- and long-distance transfers, this paper presents a depot choice model of underground express- way, and brings forward a point-line-surface planning way containing the processing of conventional 0D survey da- ta, the depot choice, the switching of OD table, the drawing of depot expectation figure and the coordinated plan- ning of the underground expressway. A case analysis is then performed. The results show that both the planning way and the depot choice model are theoretically valuable and practicably viable for the reasonable planning of un- derground expressway network.

Network Equilibrium Behaviors with Multiple Vehicle Classes, Criteria and Mixed Strategies

Liu Wei-ming Fu Ling-feng Liu Chi

2009, 37(2):  70-76. 

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In this paper, a variational inequality （VI） model is proposed to describe the network equilibrium be- haviors with multiple vehicle classes, multi-criteria and mixed strategies. The proposed model is then used to predict the flow distribution in a highway transport network under the condition of road tolling and traffic information system. In the proposed model, the users are classified according to the vehicle type and the route choice strategy that every individual user employs; the travel cost function parameters are set to reflect the differences in users with distinct vehicle types in terms of travel speed, travel cost and road toll, etc. ; the perceived travel cost functions are set to describe the variations of optimization object in route choice for users with different travel strategies; and the equilibrium condition for this specific situation is also determined. Moreover, the solution procedures for the VI model by means of an improved successive average algorithm are introduced. Numerical experiment results indicate that the proposed model well describes the roles of road tolling and traffic information system played in the network efficiency improvement, and further reveals some characteristics of the network equilibrium behaviors with mixed strategies.

A Description and Recognition Method of Curve Configuration and Its Application

Lin Pei-qun Xu Jian-min

2009, 37(2):  77-81. 

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In order to correctly describe and recognize the configuration of a time series crave （TSC） , five morphemes and one wildcard are defined according to the curve segment types, and the corresponding morpheme vector and the wildcard vector are defined for the hierarchical description of the curve. Then, one TSC is transformed into a 2D table. The second colmnn of the table makes up of a string that can effect the elementary pattern matching and the rows of the table represent the attribute vectors that can enhance the morpheme-relational operation, thus reali- zing a more complex pattern matching at the next step. Moreover, a string matching arithmetic with attribute re- straints and wildcard strings is proposed based on the classical backtracking method. The method is finally em- ployed to classify vehicles using the TSCs collected from inductive loops in a real traffic scene. The results show that the proposed method is effective and reasonable.

Genetic Algorithm for Route Optimization of Vehicle Navigation in Logistics Distribution

Wen Hui-ying Xu Jian-min Lin Zheng-chun

2009, 37(2):  82-86,91. 

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In this paper, a genetic algorithm for the route optimization of vehicle navigation in logistics distribution is presented. Then, the generation methods of the initial population, the crossover method and the mutation method are all respectively improved, and the algorithm parameters are self-adaptively adjusted. Experimental results indi- cate that the improved algorithm helps to avoid both broken routes and loop routes and to improve the searching effi- ciency and the algorithm adaptability. It is also found that, with its high speed and efficiency, the algorithm is sui- table for the real-time point-to-point route optimization of vehicle navigation in logistics distribution.

Vehicle Classification Based on Image Moment Invariant Feature and BP Neural Network

Qin Zhong

2009, 37(2):  87-91. 

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In order to effectively classify vehicles, a new classification method based on image analysis is proposed. In this method, the road background is set up according to video sequence images, and the moment invariant fea- tures of the vehicle region segmented via the background division are calculated. Then, in order to speed up the ex- traction, a Canny operator is used to detect the edge of the vehicle region and to extract the vehicle outline, and the moment invariant is directly obtained as the characteristic quantity of vehicle classification. Afterwards, a three-layer BP neural network, with the moment invariant as the input, is established, and the vehicle is then classified according to the network output. Some experiments are finally carried out to verify the effectiveness of the proposed method.

Effects of Dynamic Mechanical Properties of Grading Macadam on Tunnel Pavement Stress

Huang Xiao-ming Xu Tao Huang Cheng-zao

2009, 37(2):  92-97. 

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Grading macadam with good temperature and humidity stability is commonly laid under tunnel pavements to drain seepage from the bedrock. In this paper, some dynamic triaxial tests were performed to reveal the effect of bedrock seepage on the dynamic mechanical properties of the grading macadam layer, and a dynamic resilient model was established to describe the mechanical properties of grading macadam. Moreover, the stress state of the pave- ment was analyzed by means of the nonlinear finite element method. The results indicate that （ 1 ） dynamic triaxial tests well simulate the actual stress state of grading macadam under tunnel pavement; （2） the Uzan model conside- ring the shear performance of material better reflects the stress state of grading macadam ; （3） the regression coeffi- cient of the Uzan model presents obvious nonlinearity with the moisture variation, thus greatly affecting the dynamic resilient modulus; （4） the diminishing rate of the maximum tensile stress at the pavement bottom decreases with the increase in macadam modulus; and （5） in order to enhance its draining function and improve pavement stress states, the gradation of macadam should be rigidly controlled-specifically, the content of the macadam in the size of less than 0. 075 mm should be controlled in 5% -7% and the resilient modulus should be in 200 -300 MPa.

Acoustic Contribution Analysis of Passenger Room of High-Speed Train Under Wheel-Rail Excitation

Xiao You-gang Kang Zhi-cheng

2009, 37(2):  98-101,106. 

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A series of models of high-speed trains, including the dynamic coupling model of vehicle and track, the finite element model of train body and the acoustical boundary element model of passenger room, were established. Then, the noise distribution in the passenger room caused by track irregularity was calculated. Moreover, the panel contribution to the highest acoustic pressure in the passenger room was analyzed using the technology of acoustic transfer vector. The results show that, at the speeds of 200 and 300 km/h, the noises at sound level A in the pa- ssenger room vary within the ranges of 62.6 - 66.7 dB and 65.2 - 71.1 dB, respectively ; and that, in order to re- duce the noise at the point with the highest acoustic pressure in the passenger room, some measures should be adopted at the door on the back wall and at the third panel on the floor.

A Paving Algorithm and Its Implementation on MSC. Patran Platform

Lin Wei Zhao Cheng-bi

2009, 37(2):  102-106. 

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In order to automatically generate finite element （FE） meshes in the transverse structure of a ship, this paper presents a paving algorithm and its implementation method on the MSC. Patran platform according to the exis- ting unstructured mesh algorithms and by introducing some new rules. As compared with the existing algorithms, the proposed algorithm is more suitable for the automatic generation of FE meshes in the narrow two-dimension areas where some constraints are allowed to set. The application to the transverse structure of a ship indicates that the proposed algorithm is superior to the existing ones.

Power & Electrical Engineering

Reactive Power Optimization with Constraints of Static Voltage Stability Margin

Liu Ming-bo Qu Shao-jie Ma Guan-xiong

2009, 37(2):  107-112. 

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This paper proposes a new algorithm for the reactive power optimization with the constraints of voltage stability margin, by which the static voltage stability margin is effectively increased and the active power loss is re- duced via the adjustment of control variables. In this method, the reactive power optimization problem is decom- posed into two sub-problems. One is the nonlinear reactive power optimization and the other is the voltage stability margin and its sensitivity analysis of control variables. The two sub-problems are then alternately solved to obtain the optimal solution, respectively with the nonlinear primal-dual interior-point method and the continuous power flow method. The proposed method is of high calculation speed and good universality for various real systems. The applications to IEEE 14-bus, 30-bus and l l8-bus systems demonstrate that the proposed method is effective and that, when the load increases in a particular mode, the bifurcation type of a system may change between a limit-in- duced one and a saddle-node one due to the change in reactive power flow.

Dynamic Var Planning for Receiving Ends Based on Evaluation of State Division/Transition Cost

Zhang Yong-jun Li Yong Chen Xu

2009, 37(2):  113-117,126. 

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As the dynamic voltage stability of large-scale receiving systems is a very important factor affecting the secure operation of power systems, it is necessary to provide sufficient dynamic voltage support for the receiving sys- tems. The key factor in the dynamic var planning is the quantitative economic loss evaluation without-and-with dy- namic voltage support. In this paper, the state transition course under large disturbances of multi-infeed receiving systems is analyzed. Then, based on the evaluation of state division/transition cost, a complete optimization model of dynamic var planning is presented to describe all kinds of voltage instability situations caused by both the interior faults of receiving systems and the infeed faults. The proposed model is finally applied to the optimization of the dy- namic voltage support planning of the receiving networks in Guangdong in 2008 and 2010, and a comprehensive compensation scheme with security and economic efficiency is obtained.

Application of Decentralized H∞ Controller to Damping Control of Power System

Chen Rou-yi Zhang Yao Zhong Qing Cai Guang-lin

2009, 37(2):  118-126. 

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In order to design a decentralized H∞ controller with robustness and low dimension, the polytopic model is employed to describe the operation states of uncertain power systems as a convex set, in which the vertices are some typical operation parameters, and the homotopy parameter method is adopted to interactively solve two linear matrix inequalities for the purpose of obtaining the solutions to the controller. The proposed approach is then used to design a decentralized additive damping controller in the static var compensator （SVC） and a power system stabilizer （PSS） in an IEEE benchmark system with 19 generators. The test results show that, due to their mutual coordina- tion, the decentralized controller not only greatly improves the damping ratio and anti-interference capability of pow- er systems, but also effectively restrains the continuous oscillations resulting from serious faults. It is also demon- strated that the proposed approach in combination with the model reduction method can further reduce computational burden and is thus suitable for practical power systems.

Decoupling Algorithm for Discrete Reactive-Power Optimization of Large-Scale Power System

Zhao Wei-xing Liu Ming-bo Chen Can-xu

2009, 37(2):  127-133,157. 

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In this paper, the node tearing method is adopted to convert the discrete reactive-power optimization model of large-scale power systems into a multi-zone decomposition one, and the nonlinear primal-dual interior- point method with discrete penalty is employed to solve the decomposition model and to further obtain reduced-order linear correction equations with a block structure. In weak coupling systems, the complete coupling of the correc- tion equations is implemented by setting the off-diagonal submatrixes to zero, and the algorithm is of local linear convergence. However, in strong coupling systems, both the approximate Newton directions and the decoupled dia- gonal matrix, which are computed by the method similar to handling weak coupling systems, are respectively taken as the initial values and the preconditioner when solving the linear correction equations using the GMRES algo- rithm, thus resulting in good convergence and high calculation speed of the algorithm. The proposed algorithm is fi- nally applied to a 1062-bus and a real 538-bus systems, with its effectiveness being verified and some practical de- coupling criteria being presented.

Exact Linearization Control of State Feedback for Boost Converter

Shuai Ding-xin Xie Yun-xiang Wang Xiao-gang

2009, 37(2):  134-139. 

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By introducing the control aim into the system state equations, a nonlinear affine model of Boost converter working in current conduction mode （CCM） is set up, which is theoretically proved to satisfy the controllability condition and the involution condition for the exact linearization control of state feedback. Then, a nonlinear output function and the corresponding nonlinear state feedback control law are derived and used to implement the exact linea- rization control of state feedback of the original system. Moreover, the selection of the feedback coefficient is ana- lyzed in detail. The proposed control method dispenses with any additive voltage PI controller. Thus, it is easy to implement and is more robust to the input voltage, the load and the component parameters. Simulated results indi- cate that the proposed method is of high performance and is superior to the passivity-based control methods.

Variable-Voltage MPPT Algorithm and Simulation of Photovoltaic System

Liu Li-qun Wang Zhi-xin

2009, 37(2):  140-146. 

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It is necessary to develop an efficient maximum power point tracking （MPPT） method to improve the output efficiency of a photovohaic （PV） system. In this paper, some theoretical analyses and simulations are performed. It is found that the output photocurrent of the same piece of solar cell remains constant when the tempera- ture and irradiation are the same and when the diode quality factors and reverse saturation currents are different. Based on this conclusion, a variable-voltage MPPT algorithm that tracks the maximum power point in different weather conditions is proposed. In the proposed algorithm, the combined perturb and observe （PO） method is used to acquire the actual diode quality factor and reverse saturation current, and a comprehensive compensation without the PO method is employed to track the actual maximum power point. The correctness and effectiveness of the pro- posed algorithm are finally verified in different weather conditions.

Buck DC-AC Inverter Based on Double-Loop Control

Chen Jiang-hui Xie Yun-xiang Huang Min-jun Ming Zong-feng Chen Jing-feng

2009, 37(2):  147-151. 

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In order to improve the dynamic characteristics, robustness and anti-disturbance performance of Buck DC-AC inverters, a double-loop controller with current feedforward is presented. In this controller, the full-state feedback scheme is adopted to implement the double-loop control of voltage and current, thus improving the dynamic response as well as the steady-state performance of the inverter system. Moreover, a current feedforward loop is em- ployed to improve the anti-disturbance performance of the inverter system. Experimental results indicate that the inner loop in the double-loop controller enlarges the bandwidth of the inverter control system, quickens the dynamic response, increases the steady-state precision, and restrains the load turbulence.

Application of Hybrid Genetic Algorithm to Optimization of Pulverizing System

Liao Yan-fen Ma Xiao-qian

2009, 37(2):  152-157. 

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This paper proposes a hybrid genetic algorithm （GA） to optimize the operation of pulverizing system in admixing combustion conditions. In this algorithm, a fuzzy neural network is adopted to evaluate the slag property of admixed coal, and a Radial Basis Function neural network is used to predict the fineness of pulverized coal and the outlet temperature of the mill. Then, the pulverizing system is optimized, with the mill safety and the furnace com- bustion stability as the restraints, and with the lowest blended coal price and pulverizing unit cost as the targets. Moreover, a kind of hierarchical gene is designed to fasten the searching process. Simulated results indicate that the proposed algorithm is practicable and feasible in optimizing the operation of pulverizing system in admixing combus- tion conditions.

Optimization Control of Preparation of Coal Water Mixture Based on LSSVM-MODE

Liu Ding-ping Ye Xiang-rong Deng Hua-yu

2009, 37(2):  158-162. 

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In the production of coal water mixture （ CWM）, there exists an inconsistency between the production cost and the product performance. In order to solve this problem, the least-square support vector machine is em- ployed to establish a muhi-objective optimization model for CWM concentration and ball mill current, and the multi- objective differential evolution algorithm based on Pareto optimal concept is used to optimize the operation condi- tions, Moreover, the fuzzy set theory is introduced to obtain the satisfactory solutions in Pareto solution set. An op- timized adjustment mode of CWM concentration and some strategies to improve the CWM production benefit are fi- nally proposed in the paper.