Table of Content

25 August 2011, Volume 39 Issue 8

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Mechanical Engineering

Optimization of Tooth Shape of Multi-Tooth Mandrel for Machining Axially Inner Micro Groove Copper Tube

Li Yong Wang Xiu-kun Zeng Zhi-xin

2011, 39(8):  1-6.  doi:10.3969/j.issn.1000-565X.2011.08.001

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The multi-tooth mandrel is used to machine the axially inner micro-grooved Copper tube ( AIGCT) ,and the geometric shape of the teeth directly affects the forming quality and the tool life. In this paper,based on both the characteristics of metal flow,which is presented by using the metallographic images of the rectangle tooth cross-section during the forming of AIGCT,and the boundary features of the forming zone of a single tooth,the forming zone is divided into four parts: rigid zoneⅠ,plastic deformation zone,rigid zone Ⅱand two compacted dead zones. Then,a mathematical model of the unit extruding force is established for the forming of tooth shape by means of the upper bound method,the mechanism of the process parameters affecting the unit extruding force is then analyzed,and the angle of optimal metal flow direction and the factors to influence the optimization are thus
solved. Finally,the parameters of tooth shape of the multi-tooth mandrel are optimized.

Strain Grid Experiment of Spinning of Hollow Part with Triangular Arc-Type Cross-Section

Lai Zhou-yi Xia Qin-xiang Xu Teng Cheng Xiu-quan

2011, 39(8):  7-12.  doi:10.3969/j.issn.1000-565X.2011.08.002

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As a hollow part with triangular arc-type cross-section is investigated by a strain grid experiment,the distributions of the strain along the generatrix or in the circumferential and the thickness directions and the equivalent strain are obtained. The results show that( 1) the strain of the side wall and the opening area of spun part is tension along the generatrix direction and compression in the other two directions,and the strains along the generatrix
and thickness directions are the major ones but the strain in the circumferential direction is the minor one; ( 2) the deformation modes of the side wall and the opening area during forming are respectively the shear spinning and a complex deformation major in shear spinning but minor in conventional spinning; ( 3) on the sides of both big and small conical walls,the strain along the generatrix and thickness directions first increases and then decreases from the corner to the opening area,which are the same as the equivalent strain,but the zone with large strain on the side of the small conical wall is larger than that of the big conical wall; and ( 4) the strain distribution is mainly affected by the deformation extent and velocity: the difference in the former results in the strain distribution difference between the big conical wall and the small one; and the variation in the latter causes the strain distribution to vary along the cross-section profile.

Compound Forming of Outside 3-Dimension Integral Fins on Stainless Steel Tubes

2011, 39(8):  13-18.  doi:10.3969/j.issn.1000-565X.2011.08.003

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In this paper,a novel plowing /extrusion tool is proposed to develop a new compound forming technique of rolling-plowing /extrusion to machine outside 3-dimension integral fins on stainless steel tubes. The machining process is divided into two stages: to fabricate V-ribs by rolling and to machine 3-dimension integral fins on the V-ribs by plowing /extrusion. Moreover,the morphologies of the ribs and the fins under different processing conditions were experimentally analyzed,and the effect of the plowing /extrusion depth and feed rate on the fin height and pitch were investigated. The results show that the optimal fins are machined at a rolling depth of 1. 20mm,a plowing/extrusion depth of 0. 25 ～ 0. 45mm and a feed rate of 2. 16 ~3. 92mm/r.

Impacts of Eccentric and Installation Errors on Static Load Sharing Behaviors of Encased Differential Herringbone Train

Zhu Zeng-bao Zhu Ru-peng Bao He-yun Jin Guang-hu

2011, 39(8):  19-25.  doi:10.3969/j.issn.1000-565X.2011.08.004

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In this paper,a static model of encased differential herringbone train system with intermediate floating components is proposed based on the theory of the concentrated parameter. In this model,the curves of the eccentric and installation errors versus the load sharing factors are obtained by calculating the load sharing factors,and then the impacts of the errors on the load sharing behaviors of the train system are analyzed. The results show that ( 1) at the same initial phase angle,the eccentric errors of the planet /star gears have no influence on the load sharing factors; ( 2) unlike the planet gears of the differential stage,the load sharing factors of the star gears,which are caused by the installation errors,do not change with time in the encased stage; and ( 3) the load sharing factors of the differential stage are greater and more sensitive to the errors than those of the encased stage.

Nesting Algorithm for Irregular Parts Based on Principle of Minimum Potential Energy

Liu Xiao Ye Jia-wei Hu Jin-peng

2011, 39(8):  26-29,41.  doi:10.3969/j.issn.1000-565X.2011.08.005

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Proposed in this paper is a novel algorithm for the nesting of irregular parts based on the principle of minimum potential energy ( HAPE) ,which reveals the physical meaning of nesting problems: the part always tends to keep its center of gravity as low as possible by means of translation and rotation,thus a more compact layout being obtained. In the investigation,in order to find the optimal nesting attitude with the lowest center of gravity,some equally spaced points need to be located on the sheet,and around each point,the parts are rotated in a certainangle interval. Case analyses show that HAPE is credible and is of a clear physical meaning,and that it needs no calculation of no-fit polygon and is capable of dealing with arbitrary irregular parts.

Recognition Method of Process Feature Based on Delta-Volume Decomposition and Combination Strategy

Zhao Peng Sheng Bu-yun

2011, 39(8):  30-35.  doi:10.3969/j.issn.1000-565X.2011.08.006

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In order to solve the integration and reuse problems of design information in computer aided process planning,a method based on delta-volume decomposition and combination strategy is proposed for the recognition of process features,according to the analyses of the existing feature recognition methods. Then,the basic principle and the holistic framework of this method are respectively analyzed and introduced,and the overall feature recognition flow,including generation,decomposition,combination,search matching of the delta-volume,and capturing process features,is expounded. Moreover,some discussions are gradually carried out on the delta-volume decomposition and the combination strategy fusing geometry information,design information and process planning knowledge as well as two methods guided by this strategy,namely,the information description method of the model describing the process feature recognition and the feature doubly matching method used in the processes of the decomposition
of delta-volume and the combination of delta volume cells. Finally,the effectiveness of the proposed recognition method is verified by an example.

A Knowledge-Based Rough Set Model for Manufacturing Decision

Xu Xiao Zhai Jing-mei Liu Hai-tao Kang Bo

2011, 39(8):  36-41.  doi:10.3969/j.issn.1000-565X.2011.08.007

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Due to the complexity and uncertainties of the manufacturing system,both the knowledge modeling and the data mining modeling are restricted by incomplete knowledge and data. In this paper,in order to reduce the uncertainties by making full and effective use of the known information,an modeling idea of integrating the knowledge with the data mining is proposed to embed the knowledge into the rough set model,with the function relations of the knowledge established. Then,based on the indiscernibility relations and the function relations,a novel knowledgebased rough set model ( KBRSM) is developed and the knowledge classification and inference are investigated. As compared with the original rough set model,KBRSM is of high classification accuracy,excellent performance of knowledge discovery as well as of a generalized form. Experimental results show that the proposed decision model is effective and practically flexible.

Dynamic Modeling and Simulation of Closed-Loop Dual-Arm Space Robots

Tian Zhi-xiang Wu Hong-tao

2011, 39(8):  42-47,65.  doi:10.3969/j.issn.1000-565X.2011.08.008

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In order to implement real-time positioning and tracking of the pose of the closed-loop dual-arm space robot body,the recursive Newton-Euler kinematic equations on screw form are derived,and,according to the conservation laws of linear and angular momentum of the free-floating space robots,the dynamic equations of the closedloop system of the free-floating dual-arm space robots are set up based on the theory of spatial operator algebra. Then,the decomposition and inversion of the generalized mass matrix are achieved by means of the sequential filtering and smoothing methods of optimal estimation theory,with the high-efficiency computation for O( n) times. Finally,the closed-loop system with manipulators of 2 planes and 3 degree of freedom is simulated by using Mathematica 6.0,and the results are compared with those of the ADAMS. It is found that the proposed method based on spatial operator algebra is correct and efficient and that it can be applied to the real-time dynamic simulation of spatial
complex multi-body systems as well as the modeling analysis of control systems.

Development of Robot for Inspecting Exterior of Tubes of Heat Exchangers in Nuclear Power Plants

Li Min Zhang Ya-nan Gong Zhen-bang

2011, 39(8):  48-53.  doi:10.3969/j.issn.1000-565X.2011.08.009

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As the maintenance of heat exchangers of nuclear power plants is extremely difficult to operate manually,this paper presents a scheme of using a robot to automatically inspect the exterior of heat transfer tubes. In the investigation,the robot is developed by a modular design approach and it mainly consists of a longitudinal mobile module,a rotary module,a locating module,an extending and retracting module,a micro vehicle module,a base,and three electrical motors. The micro vehicle carries a micro camera and can move in the transverse gap of tube bundles to perform video inspection on the target areas. Moreover,the form of 3-CSR parallel mechanism is proposed,and a micro 3-CSR parallel mechanism actuated by shape memory alloy ( SMA) coil springs is designed to adjust the micro camera pose. In addition,the control system is put forward,the acceleration and the deceleration curves of the longitudinal mobile module are designed based on fuzzy control theory,and a grey evaluation method is used to evaluate the inspection results. Experimental results from the prototyping system of the robot indicate that the robot can improve the quality and efficiency of inspection,thus meeting the design requirements.

A Measurement Method of Plane Angle Based on Machine Vision

Lei Jing-fa Wang De-hui Yuan Zhong-fan

2011, 39(8):  54-59.  doi:10.3969/j.issn.1000-565X.2011.08.010

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In order to overcome the difficulties in the real-time measurement of plane angle in many fields such as manufacture and architecture,a non-contact measurement method is proposed based on machine vision. In the method,first,a circle and its center are marked in each of two planes to be measured,and only one digital camera with known intrinsic parameters is needed to take photos once in any position so as to obtain one image with the centers and all or part of the circles. Then,the equations of the images of the circles and the coordinates of their centers are acquired by means of the least square method,thus achieving the equations of the vanishing lines in the two planes and the coordinates of the vanishing points in the normal directions of the two planes. Finally,according to the imaging equation of the camera,the angle between the normals of the two planes,whose supplementary angle is just the angel between the two planes,is figured out by using the coordinates of the vanishing points and the intrinsic parameters of the camera. Experimental results show that the proposed method is simple and feasible,with a relative measurement error of less than 1%,which can meet practical requirements satisfactorily.

Fast Image Mosaic Method for Large-Scale Workpiece Measurement System

Quan Yan-ming Li Shu-mei

2011, 39(8):  60-65.  doi:10.3969/j.issn.1000-565X.2011.08.011

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According to the characteristics of the image mosaic of the large-scale workpiece measurement system,an improved fast mosaic algorithm with high accuracy is proposed by combining the feature extraction with the template matching. In this algorithm,first,the feature points of two adjacent images are extracted by using the multiscale Harris operator. Then,in the first image,the templates are identified according to the distribution of the feature
points; and in the second image,the matching blocks are chosen by means of the template matching. Finally,the matching feature points in the matching blocks are detected by the feature matching,and the mosaic is thus completed. Experimental results show that the proposed algorithm greatly reduces the computation amount of the mosaic,effectively avoids the false matching which is easy to occur due to scarce features and large-scale similar areas of the workpiece,thus meeting the requirements of the measurement system.

Chemistry,Chemical & Energy Engineering

Performance and Field Synergy Analysis of Alcohol-Based Fuel Burner

E Jia-qiang Zhang Shuang-li Fu Xue-zheng Li Yu-qiang Dong Jiang-dong Zhang Bin

2011, 39(8):  66-71.  doi:10.3969/j.issn.1000-565X.2011.08.012

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Aiming at the mechanism of alcohol-based fuel burner with the diffusion combustion of methanol fuel,the Arrhenius limited reaction rate model and the eddy break-up combustion model are established,and numerical simulation and field synergy analysis are conducted by taking into consideration the heat loss due to convection and radiation. The results show that,when the excess air coefficient is 1. 1~1. 2,the mass fractions of NO_x and CO at
the burner outlet are both low,while both the average temperature and the maximum temperature are high,thus bringing about excellent performance on the part of the burner; furthermore,when the pressure is 0. 18~0. 19 MPa,the synergy between the velocity field and the temperature field proves to be the best,thus the best effect of the alcohol-based fuel burner being achieved.

Investigation into Model and Thermal Performance of Single Thermal Storage Tank with High-Temperature Molten Salt

Yang Xiao-ping Yang Xiao-xi Ding Jing Yang Min-lin Jiang Run-hua

2011, 39(8):  72-76,108.  doi:10.3969/j.issn.1000-565X.2011.08.013

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In this paper,the performance of a single thermocline packed bed storage tank is analyzed,with hightemperature molten salt as the heat transfer fluid. Then,a theoretical model of the thermal storage system is established to reveal the law of thermal storage by means of numerical simulation. Moreover,the method to evaluate the performance of the thermal storage tank is put forward based on the capacity,the ability,the entropy generation,and the effectiveness,etc,and the effects of physical properties of different filler materials on the performance of the thermal storage system are analyzed. The results show that,under certain conditions of thermal storage,higher thermal conductivity are unfavourable to enhance the performance of the thermal storage tank,and that higher heat capacity per unit volume may result in better comprehensive thermal storage performance as well as high entropy generation.

Effect of Ultrasonic on Corrosion of Zinc in Hydrochloric Acid

Lu Yi-gang Song Heng-ling

2011, 39(8):  77-81.  doi:10.3969/j.issn.1000-565X.2011.08.014

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In the consideration of the attenuation of ultrasonic,the actual sound power of several ultrasonics with different frequencies and power in the liquid was determined via the calorimetric method. Under the conditions with and without ultrasonic,the corrosion rates of zinc in the hydrochloric acid solution were determined by means of the gravimetric method. Moreover,by changing the ultrasonic frequency and power parameters,the relationships between the corrosion rate and these parameters were investigated. In addition,the morphology of zinc corrosion was observed by means of scanning electron microscopy,with the causes for the acceleration of zinc corrosion being also analyzed. The results show that( 1) the corrosion of zinc in the hydrochloric acid solution is significantly accelerated by ultrasonic,and ultrasonic cavitation plays an important role in the accelerated process; ( 2) at the same power,the low-frequency ultrasonic induces the cavitation more easily,thus making the corrosion rate higher; and( 3) when the frequency is constant and the power is not too high,the corrosion rate increases with the power increase.

Investigation into Physicochemical Properties of Xylan Derivatives with High Degree of Substitution

Peng Xin-wen Ren Jun-li Sun Run-cang

2011, 39(8):  82-86.  doi:10.3969/j.issn.1000-565X.2011.08.015

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Bifunctional xylan derivatives ( XDs) with high degree of substitution were prepared from native xylan in wheat straw,with acrylamide as the etherifying agent,alkali as the catalyst,and butanol /water mixture as the reaction system. Then,the structure of the products was characterized by means of 13C NMR. Moreover,the dynamic rheological behaviors and thermal stability of XDs and the native xylan were tested by using a parallel-plate rheometer
and a simultaneous thermal analyzer, respectively. The results show that,as compared with the native xylan,the shear-thinning phenomenon of XDs solution is significant,with relatively lower viscosity,storage modulus and loss modulus,that the storage modulus is higher than the loss modulus,and that the thermal stability of the xylan declines after the modification.

Preparation of Calcium Carbonate Composite Filler Coated with Titanium Dioxide and Its Application in Papermaking

Chen Gang Liu Ya-ping Fang Zhi-qiang

2011, 39(8):  87-92.  doi:10.3969/j.issn.1000-565X.2011.08.016

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A new kind of composite filler was prepared by coating the carrier of calcium carbonate,with titanium dioxide via the mechanochemical method. Then,the structure of the composite filler was characterized by using such parameters as oil-absorbed values,hiding power and particle size and by means of FT-IR and SEM,and the properties of the composite filler and its effect on paper were then investigated. The results show that( 1) the particle size of the composite filler is larger than the uncoated calcium carbonate; ( 2) the chemical bonds form between calcium carbonate and titanium dioxide and is of a good strength; ( 3) the hiding power and the oil absorption values of the composite filler are close to those of titanium dioxide; and( 4) at the same ash content,the optical properties and the physical strength of the paper filling with the composite filler are close to those of the paper filling with titanium dioxide,thus the composite filler being able to partly or wholly replace titanium dioxide.

Effects of Molecular Structures of Polycarboxylate on Early-Strength Performance of Cement Mortar

Yi Cong-hua Huang Xin Zhang Zhi Yang Dong-jie

2011, 39(8):  93-98.  doi:10.3969/j.issn.1000-565X.2011.08.017

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A series of polycarboxylate superplasticizers were synthesized with methacrylic acid ( MAA) ,sodium methylacrylamide ( MAS) and methoxy polyethylene glycol methacrylate( PMA45) as monomers,and ammonium persulfate ( APS) as an initiator. Then,the effects of raw material proportion on the early-strength performance of polycarboxylate superplasticizers were investigated by measuring the early strength of harden mortar and by using a scanning electron microscope to observe the morphology of early cement stone. The results show that the earlystrength performance of the superplasticizers first increases and then decreases with the increase of the dosage of PMA45,and increases with the increase of the dosages of MAA and MAS as well as with the decrease of the relative molecular mass of the superplasticizers,which means that the superplasticizers with optimal density of side chain ( polyethyleneglycol) ,high contents of carboxylate and sulfonate,and low relative molecular mass are of excellent early-strength performance.

Traffic & Transportation Engineering

Forecast and Analysis of Passenger Flow of Urban Rail Transit Under Iterative Feedback Constraints

Chen Da-wei Xiao Wei-zhou Li Xu-hong He Liu

2011, 39(8):  99-103.  doi:10.3969/j.issn.1000-565X.2011.08.018

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Based on the analyses of the existing problems in the forecast of passenger flow of urban rail transit in China,a forecast model framework and a method are proposed under the iterative feedback constraints. In the investigation,according to urban master planning and detailed regulatory planning along the railway,the basic data is processed to regain the balance between the population and the employment opportunities in the research by coordinating the development intensities of the whole and the local. Then,by taking into consideration the impact of vehicle flow on buses,the traditional four-stage model is improved to make motor vehicle flow assignment model,traffic distribution model and mode split model interact with each other and implement iterative feedback. As a result,the balance convergence is achieved. Finally,the proposed forecast model was testified based on the passenger flow in Suzhou Rail Transit Line 2. The results show that,when the iterative times for three particular years respectively reach 7,9 and 10,the convergence conditions and the accuracy requirement are both met.

Evaluation Model of Fuel Economy of Urban Road Section

Feng Yu-qin Leng Jun-qiang Zhang Ya-ping Li Han-wu Zhang Chun-ping

2011, 39(8):  104-108.  doi:10.3969/j.issn.1000-565X.2011.08.019

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In order to improve traffic management and reduce energy consumption in urban road traffic,the relationship between the traffic flow status and the fuel economy of road traffic is investigated by introducing the concept of economical fuel-consumption saturation and presenting the evaluation parameter of fuel economy. Then,based on a large number of field-measured data of fuel consumption,the evaluation models of fuel economy are established respectively for expressway,trunk road,secondary trunk road and branch,and the economical fuel-consumption saturation for the above four types of roads in Harbin is figured out. The results of model validation show that the proposed models can accurately describe the relationship between the traffic flow status and fuel economy,thus providing the theoretical basis for the improvement of traffic management from the viewpoint of energy saving.

Improved Particle Swarm Optimization Algorithm of Ergodic Model for Routing Planning of Delivery Vehicle Navigation

Zhang Quan Wen Hui-ying Sun Bo

2011, 39(8):  109-112,117.  doi:10.3969/j.issn.1000-565X.2011.08.020

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Vehicle routing planning is known as the key link in the logistics delivery vehicle navigation system as well as the precondition for the logistics delivery routing guidance and the technical support for vehicle navigation. In order to solve the routing planning problem,an ergodic model is established for Vehicle Routing Planning of Navigation in Logistics Distribution ( VND) ,and an improved particle swarm optimization algorithm is proposed to
solve the model. Then,the generation method of the initial population and the evolutionary strategy of the population are improved to work out the PSO algorithm which originally can not be directly used to solve the VND problem,thus achieving good results in solving the VND problem. Case studies show that the algorithm is of fast computing capability and preferable convergence.

Safety State Evaluation of Freeway Section in Mountains Based on PNN

Wen Hui-ying Luo Jun Li Jun-hui

2011, 39(8):  113-117.  doi:10.3969/j.issn.1000-565X.2011.08.021

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In this paper,first,the concepts of safety state of section and the freeway in mountains are defined and under such definitions,the concept of freeway section in mountains as well as the safety evaluation indexes and standard of the section is put forward. Then,the speed parameters are obtained by installing the traffic information collection equipment near the section requiring evaluation and its upstream. Finally,with real －time speed parameters and historical data of traffic accidents as the evaluation indexes,a safety state evaluation model of freeway section in mountains is established based on the proposed evaluation standard and the probabilistic neural network ( PNN) . Simulated results indicate that the proposed model is capable of evaluating the safety state of freeway section in mountains.

Bi-Level Programming Model for Scheduling and Procurement Scheme of Regional Bus

Wei Ming Jin Wen-zhou Sun Bo

2011, 39(8):  118-123.  doi:10.3969/j.issn.1000-565X.2011.08.022

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With the help of a bi-level programming model,the relationship between regional bus scheduling and its procurement scheme is explored from the viewpoint of system theory. According to proposed model’s characteristics,the above issue is equivalently converted into how to assign vehicles to cover all trips to maximize their utilization and determine the vehicle type to minimize the purchase expenses under different numbers of vehicles,where side constraints such as the depot capacity,the fuelling, the emission of polluting gases,etc.,are taken into consideration. The corresponding solutions of upper and lower model to different numbers of vehicles are obtained by using genetic algorithm and the optimal solution is selected by comparing all feasible schemes. Finally,the correctness and effectiveness of the proposed model and the algorithm are verified by an example.

Empirical Analysis of Escalator Capacity

Weng Xiao-xiong Li Jun

2011, 39(8):  124-128.  doi:10.3969/j.issn.1000-565X.2011.08.023

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In recent years,the utilization of the escalator in public buildings and large transportation hubs has become more and more frequent and popular. Its capacity is a vital factor in the design of the escalator because it has a direct bearing on the crowd evacuation. However,it is difficult to describe the corresponding dynamics characteristics.For some traffic facilities with complex dynamics characteristics,empirical analysis proves to be very effective,workable and precise. Therefore,by filming the peak flow of the ascending escalator in several stations of Guangzhou Metro and by processing the relevant data,the corresponding diagrams of basic traffic characteristics are established to describe the behaviors of pedestrians in the escalator entrance and on the escalator at a stairway width of 1 meter. The results of the analyses show that the actual escalator capacity is 8655 persons per hour,which accounts for 90% of the theoretical one.

Dynamic Modulus Prediction Model of ATPB Mixture

Pan Yan-zhu Wang Duan-yi

2011, 39(8):  129-132.  doi:10.3969/j.issn.1000-565X.2011.08.024

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With the development of the asphalt pavement mechanistic-empirical design and analysis methods,the research of pavement material parameters is becoming more and more significant. In this investigation,the MTS system was used to do the dynamic modulus test for ATPB-25 and ATPB-30,which are both asphalt treated permeable base( ATPB) mixture. During the test,different measuring temperatures and loading frequencies are set according to the temperature environment of the asphalt mixtures. Then,based on the test results,a full time-domain dynamic modulus master curve and corresponding master curve equation of the asphalt mixture are created. By these experiments,high-quality parameters for the optimization design and performance analysis of asphalt pavement structure with ATPB can be established. These studies are of great significance in extending the service life of the asphalt pavement. asphalt mixture; dynamic modulus; master curve; pavement mechanics; empirical design

Power & Electrical Engineering

Secondary Voltage Emergency Control Considering Transient Voltage Stability

Liu Ming-bo Gao Qiang Lin Shun-jiang Chao Zhu

2011, 39(8):  133-139,150.  doi:10.3969/j.issn.1000-565X.2011.08.025

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In this paper,a new set of differential-algebraic equations and a secondary voltage control ( SVC) emergency control strategy are proposed to respectively analyze and solve the power system transient voltage stability problem. In this emergency control strategy,the control time constant of SVC is reduced based on normal SVC,the voltage deviation of the bus,which is of the most serious voltage instability after system fault,is introduced in the object function of SVC,and the active set method is adopted to solve the quadratic programming model with the SVC emergency control. Moreover,a simulation model including SVC and primary voltage control ( PVC) is established for the transient voltage stability in power systems in PSAT environment. The correctness and effectiveness of the proposed control strategy and model are verified by the simulation results in the New England 39-bus system.

Parameter Optimization Design of PSS Based on Functional Sensitivity

Xue Zhen-yu Fang Da-zhong Yuan Shi-qiang

2011, 39(8):  140-145.  doi:10.3969/j.issn.1000-565X.2011.08.026

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Proposed in this paper is a new conjugate gradient approach for the coordination of the power system stabilizer ( PSS) parameter optimization of multi-machine power system. In this approach,combination functional index is introduced as a performance index to evaluate the damping effect of PSS,the integral term of the index is dealt with by means of the variational method,and a backward trajectory integration approach is put forward to calculate the gradient of the index to the PSS parameter vector. Moreover,minimizing the index is taken as the objective function of the optimization model of the PSS parameter,and the objective function considers the nonlinear features of big disturbance of the power system,so that the optimized PSS can improve the small-disturbance stability of the power system and efficiently damp the power oscillation caused by large disturbances. In addition,the practicality and effectiveness of the proposed method are verified on IEEE 4-generator 2-area and IEEE 10-generator New England test systems.

Hydropower Pricing Model Based on Pareto Optimality

Zhang Yong-jun Lin Jian-xi Zhai Wei-fang Zhong Wei-liang

2011, 39(8):  146-150.  doi:10.3969/j.issn.1000-565X.2011.08.027

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In this paper,both the allocation method based on the Shapley value and Pareto optimality theory are introduced. By means of the former,the penalty factor and the reward factor of hydropower pricing at different times are determined. And based on the latter,a novel differentiated hydropower pricing model is established to offer effective economic signals,for the purpose of minimizing the reduction ratio of economic benefits for small hydropower
plants to that in the line loss of power network,which can result in a low line loss and simultaneously ensure a weak effect of the pricing on the economic benefits for small hydropower plants and the power network. Case analyses show that the proposed model can bring about a win-win situation for small hydropower plants and the power network.

Analysis of Articles，Authors and Citations in Journal of South China University of Technology ( Natural Science Edition) from 2006 to 2010

Xu Hua-tao Liu Shu-hua Niu Xiao-guang

2011, 39(8):  151-158.  doi:10.3969/j.issn.1000-565X.2011.08.028

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By using the biblio-metrics method,articles,authors and citations in 60 issues of Journal of South China University of Technology ( Natural Science Edition) ( Journal of SCUT for short) from 2006 to 2010,were statistically analyzed. The results were then compared with those in the literature. It is found that ( 1) a large number of articles are yearly published in Journal of SCUT,among which the number of articles on the subject of "Electronics,Communication & Automation Technology”is the largest and has been increasing year by year; ( 2) in this journal,90.69% of the published articles are supported by foundation funds,the average publication delay of articles shows a gradual decrease; ( 3) 97.99% of the articles are co-authored and the average number of the authors of each article is 3.36; ( 4) Besides the United States,the first authors are from twenty-four provinces,autonomous regions and municipalities as well as Hong Kong in China; ( 5) 42.12% of the authors are professors or associate
professors,78.51% of the authors hold the Ph. D. degree or are post doctorates,30.31% of the authors are at the age of less than 30,and 38.83% of the authors are between the ages of 31 and 40; and ( 6) the average number of references per paper is 12.03,62.07% of which are written in English,and 73.84% are cited from journals,which indicates that the journal is of a high-level citation in varied types.