Table of Content

25 February 2013, Volume 41 Issue 2

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Electronics, Communication & Automation Technology

Ray-Space Interpolation Based on Affine Projection

2013, 41(2):  1-6.  doi:10.3969/j.issn.1000-565X.2013.02.001

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In order to effectively deal with the shape variation and noise pollution of the corresponding area in diffe-rent views and, thereby, improve the quality and speed of viewpoint image synthesis, a ray-space interpolationmethod based on affine projection is proposed. In this method, first, the scale-invariant feature transform is appliedto the feature detection and image matching for determining the affine transformation matrix among multi-viewpointimages. Then, ray-space interpolation is implemented via the projection through affine transformation matrix. Finally,a virtual viewpoint image is synthesized in the wavelet transform domain. Experimental results show that the pro-posed method is superior to the traditional block-matching interpolation and DDFI (Disparity Domain Filtering In-terpolation) methods in terms of PSNR and computation time of the virtual viewpoint image.

Retinex Enhancement Algorithm with Scale Optimization andMicro Vision Image Enhancement

Yu Jin-dong Zhang Xian-min Chen Zhong

2013, 41(2):  7-11.  doi:10.3969/j.issn.1000-565X.2013.02.002

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Due to the existence of non-uniform illumination, magnification effect of optical microscope and opticaldiffraction, etc. , micro-vision images are of large dynamic range, low overall pixel gray value, low contrast of finestructure to background and low signal-to-noise ratio. In order to improve the image quality, a Retinex enhancemenfalgorithm with scale optimization is proposed. This algorithm uses the contrast to design an optimization criterion ofGauss smoother convolution kernel scale for the reasonable estimation of illumination component. The algorithm isthen applied to the enhancement of simulated images and micro-vision images generated under various coaxial lightintensities. The results show that the proposed algorithm is superior to the homomorphic filtering one because it im-proves the contrast and reserves the image details within the dynamic compressing range.

Disparity Estimation Algorithm Based on Color Segmentation and Graph Cut Algorithm

Yuan Hui Li Zhi-bin Liu Wei

2013, 41(2):  12-18.  doi:10.3969/j.issn.1000-565X.2013.02.003

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In order to improve the accuracy of disparity estimation, an algorithm based on color segmentation and graph cut algorithm is proposed. In this algorithm, the current image is segmented into several color areas by em-ploying the mean shift algorithm, and the graph cut is implemented on the pixel set of each color area to allocate disparities for the pixels in the color area. Unlike the traditional global optimization algorithm, the proposed algo-rithm takes the pixel set of a color area rather than the whole image as an entirety to perform the global optimiza-tion, thus improving the disparity accuracy of object boundaries. Experimental results demonstrate that the proposed algorithm is more effective than the traditional one.

Tuning of Microwave Filters Based on Vector Fitting and Aggressive Space Mapping

2013, 41(2):  19-23.  doi:10.3969/j.issn.1000-565X.2013.02.004

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In order to fast diagnose microwave filters and save the tuning time, a computer-aided tuning method based on the vector fitting (VF) and the aggressive space mapping (ASM) is presented. In this method, the equivalent circuit parameters of the filter are extracted by using the VF, and the tuning value of tuning screws is predicted through the ASM. Thus, the fast tuning of microwave filters is successfully implemented. The proposed method is then applied to a four-order cross-coupled filter and a six-order Chebyshev filter, with ideal responses being obtained respectively through only three or four iterations, which means that the proposed method is accurate and effective.

Vibration Control of Flexible Beam Based on Lyapunov Direct Method

Liu Yu Huang Hao-wei Wu Yi-lin Wu Xin-sheng

2013, 41(2):  24-29,43.  doi:10.3969/j.issn.1000-565X.2013.02.005

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In order to avoid control spillover and implement real-time control of the system, a proportional-deriva-tive (PD) boundary controller is proposed for the active vibration control of a flexible beam with unknown boundary disturbance and varying tension. The proposed controller, which is based on the infinite-dimensional distributed pa-rameter model of the flexible beam, employs the boundary control technique and Lyapunov's direct method to re-duce the beam vibration. With the proposed boundary control method, uniform boundary and exponential stabilityare both achieved under external disturbances. The proposed PD controller is simple and is independent of the pa-rameters of the flexible beam system. Moreover, it ensures the real-time and robust control of the system. Simula-tion results indicate that the proposed control method effectively suppresses the vibration of the beam and reduces the vibration amplitude as well.

Flight Control Design of Unmanned Helicopter Based on Robust Integral Filtering Backstepping

He Yue-bang Pei Hai-long Zhao Yun-ji Li Jian-qiang

2013, 41(2):  30-36.  doi:10.3969/j.issn.1000-565X.2013.02.006

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As the existing model of unmanned helicopters is of high order, great difficulty in precise modeling and low robustness to external disturbances, the design of the normal backstepping method-based controller for helicop-ters encounters such problems as high calculation complexity, poor disturbance resistance and inaccurate trajectory tracking. In order to solve these problems, a robust integral filtering backstepping controller is proposed, which uses filters to compute the time derivatives of virtual controlled variables for avoiding the differential explosion in the normal backstepping controller, and introduces an integral term and a discontinuous robust term to improve the dis-turbance resistance and eliminate the static error of trajectory tracking. Theoretical analysis and simulation results show that the proposed method is effective and feasible.

Traffic & Transportation Engineering

Setting Model of Safe Distance of Advance Guide Signs at Highway Exits

Liu Wei-ming Deng Ru-feng Zhang Yang Zhuang Yan-hao

2013, 41(2):  37-43.  doi:10.3969/j.issn.1000-565X.2013.02.007

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In order to improve the safety performance of advance guide signs (AGSs) at highway exits for the di-verging area, the characteristics of the diverging area and the visual recognizing-exiting behaviors of the driver are taken into consideration, and a setting model of safe distance of AGSs, which reveals the effects of traffic flow, de-sign speed and lane number on lane-changing behaviors, is constructed based on the analysis of the computation mode of lane-changing driving distance. Then, a simulation is carried out with TSIS-CORSIM. The results indicate that, for a three-lane expressway with a design speed higher than 110km/ h, an AGS setting distance of 700m may result in minimum lane-changing number of vehicles proportionally dispersed in the diverging area, which means that the safe distance is reasonably set.

Density Dispersion Model of Bus Platoon on the Assumption of Speed-Followed Truncated Normal Distribution

Wu Wei-tiao Shen Lü-ou Jin Wen-zhou

2013, 41(2):  44-50.  doi:10.3969/j.issn.1000-565X.2013.02.008

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On the basis of field collected data and aiming at the large amount of bus traffic flow in urban arterials in China, this paper investigates the special operation characteristics of buses different from cars. Then, by using the truncated normal distribution of speed and by adopting the average stop time of buses in the station, a density dis-persion model of bus platoon in the presence of bus station in adjacent intersections is proposed. The dispersion characteristics of the bus platoon that moves down along the road during the green time are analyzed, and a piece-wise density distribution function of the bus flow is constructed in time-space coordinates. Moreover, by taking the signal coordination control of an intersection with a bus station as the example, an expression is deduced to calcu-late the number of cars in the conditions in which the front of the platoon has passed but the rear of the platoon has not passed a downstream point. Besides, the flow distribution mode in the upstream and downstream intersections is analyzed. Case study and numerical analysis show that the proposed model is effective.

SEM-Logit Integration Model of Travel Mode Choice Behaviors

Chen Jian Yan Qi-peng Yang Fei Hu Ji

2013, 41(2):  51-57,65.  doi:10.3969/j.issn.1000-565X.2013.02.009

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In the existing model of travel mode choice behaviors, only the observable characteristics of the traveler's socioeconomic status and travel plan are considered, while the latent variable (LV) affecting the travel mode choice is ignored. In order to solve this problem, the concept of LV in travel behaviors is proposed, and the causal rela-tionships between the LV and the manifest variable as well as between the LV and its measurement variables are de-scribed by using a structural equation model (SEM). Then, based on the maximum utility theory, a SEM-Logit in-tegration model containing both the LV and the manifest variable is constructed by improving the utility function of travel mode in the Logit model. The results show that, as compared with the traditional Logit model, SEM-Logit in-tegration model improves the goodness and the maximum likelihood value respectively by 0. 201 and 20. 607, which means that the LV plays an important role in travel mode choice behaviors and that the proposed model is of higher explanatory ability and accuracy.

Timing Optimization of Traffic Signals for Emergency Evacuation in Sudden-Onset Disasters

Lin Ci-yun Gong Bo-wen Zhao Ding-xuan Yang Zhao-sheng

2013, 41(2):  58-65.  doi:10.3969/j.issn.1000-565X.2013.02.010

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Aiming at the frequently-occurring sudden-onset disasters and insufficient emergency traffic guarantee ability in the world, this paper analyzes the influences of sudden-onset disasters on the urban traffic network and travel behaviors, and proposes a timing optimization model of traffic signals for emergency evacuation in sudden-onset disaster areas. The model, which is based on the dynamic traffic assignment theory and the route choice beha-viors of drivers in sudden-onset disasters, is then optimized by using a parallel ant colony algorithm to accelerate the speed of solving the problem and improve the global convergence ability. Finally, a cluster computing platform is constructed to test the proposed model and algorithm. The results show that the parallel ant colony algorithm helps to obtain better time performance and higher optimization efficiency, thus meeting the real-time demands of on-line decision support for the emergency traffic guarantee system.

Interactive Relationship Between Urban Arterial Transit Route and Land Use in TOD Mode

Ding Chuan Xie Bing-lei Wang Yao-wu

2013, 41(2):  66-73.  doi:10.3969/j.issn.1000-565X.2013.02.011

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In this paper,the features of urban arterial transit route and its surrounding land use in the transit-oriented development(TOD)mode are analyzed,and a model describing the interactive relationship between the route and the land use is established based on nonlinear differential equations.Then,the dynamic evolvement and trend of the urban alterial transit route and the land use ale analyzed.Moreover,by taking into consideration the coordinated development of the urban arterial transit route and its surounding land use in the TOD mode,the proposed interac-tive relationship model is modified.and the stability and conditions for the equilibrium state are discussed based on the differential equation stability theory.Finally,a simulation is carried out with Simulink to verify the interactive relationship.The results show that the established model welI describes the interactive relationshiD and dynamic evolvement between the urban arterial transit route and the land use in the TOD mode

Mean Shift Tracking with Adaptive Kernel Window Size and Target Model

Li Qi Shao Chun-fu Yue Hao

2013, 41(2):  74-81.  doi:10.3969/j.issn.1000-565X.2013.02.012

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When the shape,direction or color of the target changes,the traditional mean shift tracking algorithm often drifts and even fails because of its kernel window with fixed size and direction as well as its constant target model.In order to solve this problem,this paper proposes a new method that can adaptively adjust the size and direction of the kernel window,and presents a mechanism to update the target model.In the investigation,first,based on the ellipse obtained by fitting the convex hull of the target,the Kalman filtering model is used to calculate the optimal estimation of the target scale and orientation.Then,according to the estimation of the target scale,the size and direction of the kernel window are adjusted,and the distribution of the kernel weight is corrected.Finally,according to the shape and color information,a target model updating mechanism adaptive to the target change is presented.The proposed algorithm is applied to the tracking of video sequences of humans and non-motor vehicles under different scenes.The results show that the algorithm can accurately and stably track the target with obvious changes of scale,orientation and color.

Finite Element Analysis of High Full-Space Support Scaffold of Cast-in-Situ Box Girder

Su Wei-guo Liu Jian

2013, 41(2):  82-87.  doi:10.3969/j.issn.1000-565X.2013.02.013

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In order to guarantee the safety of high full-space support scaffold,the mechanical behavior and defor-mation of the support scaffolds should be comprehensiVely investigated.In this paper,the finite element method,which is the preferred numerical calculation method for complex structures,was employed to develop a finite ele-ment model of the high full-space support scaffold for the construction of cast-in-situ box girder of a main line bridge on an interchange of an expressway,and the axial force,tensile stress,compressive stress and displacement of the supporting system were numerically analyzed.Then,in order to verify the safety of the supporting system and the reliability of the numerical calculation,the settlement and compressive strain at each measure point of the supporting system were monitored in the presence of provisional preloads on an actual system.The results show that(1)neither the maximum stress nor the displacement exceeds the tolerance values of the supporting steel tube;(2)the stiffness and stability of the supporting system both meet the construction requirements well;and(3)the finite element simu-lation tool Midas is feasible in simulating high full-space suppot scaffold systems.

Microscopic Structure Evaluation of Aggregates Based on Laser Measurement and Vacuum Coating Technology

Li Zhi Liu Tao Liu Chun-lei

2013, 41(2):  88-93.  doi:10.3969/j.issn.1000-565X.2013.02.014

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The microscopic structure of aggregates is of crucial importance to the skid resistance of asphalt pavement.In this paper,the microscopic structures of four kinds of aggregated rocks with different materials were evaluated by using a serf-developed high-accuracy laser-texture instrument,and the aggregate texture curve was quantitatively evaluated with the box-counting dimension method.Then, the vacuum coating technique was adopted to eliminatethe effects of aggregate lithology,surface color and microscopic crystal and to improve the measurement accuracv of fractal dimension.The results show that the box-counting dimension method can effectively describe the micro-rexture of different aggregates，and that the vacuum coating technique can remarkably improve the measurement accuIlacv.

Mechanics

Parametric Vibration and Corresp0nding Impact Parameters Analysis of Suspender Cable Considering the First Two Order M odals

Li Zhou Wei Yuan-cheng

2013, 41(2):  94-100.  doi:10.3969/j.issn.1000-565X.2013.02.015

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Cables of suspension bridges possess strong nonlinear characteristics under both static and dynamic forces,and,under the boundary excitation with certain frequency ratio,they may perform parametric vibration with the amplitude being much more than the initial value.In order to solve this problem,a parametric vibration model of suspender cable, which takes the bridge deck vibration as the boundary excitation and considers the first two or-der modals,was established.Then,by taking the super-large Aizhai suspension bridge as an engineering example,the first-order and the second-order parametric vibrations of the suspender cable under boundary excitation in the finished bridge state were analyzed,the same excited conditions and the response characteristics of parametric vibration of the suspender cable were determined by using the multi-scale method and the Runge-Kutta method,and the effects of excitation amplitude,cable length and initial disturbance on the resonant response amplitude were in-vestigated.The results indicate that the suspender cable of long-span suspension bridges under deck vibration may perfoIm a parametric vibration with the vibration ratio of 1:1 or 1:2,and that the excitation amplitude,the cable length and the initial disturbance affect the response amplitude and the response time to a certain degree.

Contact Model of Two Rough Surfaces Under Combined Compression-Shear Load

Zheng Heng-bin Huang Shi-ping Yah Quan-sheng Wu Je Mo Zeng-mo

2013, 41(2):  101-104,128.  doi:10.3969/j.issn.1000-565X.2013.02.016

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Although the contact analysis of rough surface is widely used,the corresponding contact mechanism is still unclear.In order to solve this problem,a contact model of two rough surfaces under combined compression-shear lcad is proposed. In this model.the Weibull distribution function is introduced to describe the combined roughness of asperity contact,and a shifted spherical harmonics expansion is employed to describe the contact orien-tation probability distribution.Analytical results show that roughness greatly affects the normal and shear stiffness,and that the asperity contact orientation,which is an important parameter of the model,also remarkably affects the shear stiffness.The analytical results accord well with the experimental ones,which means that the proposed model is of high effectiveness.

Finite Element-Based Order Reduction M ethod for Nonlinear Buckling Analysis of Structures

Liang lie Sun Qin Zafer Gurdal

2013, 41(2):  105-110.  doi:10.3969/j.issn.1000-565X.2013.02.017

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Based on Koiter’S initial post-buckling theory and the incremental iterative method of the Newton method,an order reduction method that automatically tracks the nonlinear equilibrium path is proposed.In this method,the perturbation load and the deformation on the primary path are introduced to make the perturbation to expand at any point along the path.In each perturbation step,the nonlinear solution obtained from the reduced-order model is taken as an initial prediction of the structural response and is corrected with the residual lcad obtained by the FE model.Then,the corrected solution is taken as the expansion point of the next perturbation step,and the reduced-ordermodel is updated to reflect the change of structural stiffness.Numerical examples show that the proposed method is of high accuracy for the nonlinear analysis,and that the number of the linear systems of equations(the scale of which equals that of the full finite element model)needed to be solved is much less than that of the general nonlinear finite element method.

Materials Science & Technology

Preparation and Reflection Characteristics of ZnO-Fe₂O₃-Na₂O-P₂O₅ Solar Heat Reflection Materials

Wang Da Zhou Xi-ya Su Da-gen

2013, 41(2):  111-116.  doi:10.3969/j.issn.1000-565X.2013.02.018

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A kind of solar heat reflection material,Na₂O-ZnO-Fe₂O₃-P₂O₅,was prepared via coprecipitation and was characterized by means of UV-Vis-—NIR spectroscopy and XRD.The results show that(1)when the Zn/Fe no-lar ratio is 9.00,the phase composition of the products calcined at 700℃ varies with the Zn/P molar ratio(1.52,1.02,0.76 and 0.61),in which a Zn/P molar ratio of 0.61 may result in a single-phase NaZnPO4 structure while the other ratios may result in multiphase structures;(2)when the Zn/P molar ratio is 0.61,the phase composition of the products calcined at 700 oC is independent of the Zn/Fe molar ratio(19.00,9.00,5.67 and 4.00),with all the products being of a single-phase NaZnPO₄ structure,however,these products become dark and the reflee-tance decreases with the decrease of the Zn/Fe molar ratio;and(3)at a Zn/P molar ratio of 0.61 and a Zn/Fe molar ratio of 9.00,the products calcined at 500～800℃ are all of a single-phase NaZnPO₄ structure,and the Droducts become dark and the reflectance decreases with the increase of the calcination temperature,for instance,the DIl0ducts calcined at 600 and 700℃ are respectively orange and red,with their reflectance being 80.7% and 72.2%,respectively.

Laminated Al₂O₃/Al Composites Bonded by Epoxy Resin Adhesive

Li Wei-xin Lu Ying Xie Ming-gui Yin Hao-dong Rao Ping-gen

2013, 41(2):  117-122.  doi:10.3969/j.issn.1000-565X.2013.02.019

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Laminated Al₂O₃/Al ceramic composites were successfully fabricated via a simple molding process at room temperature and 5 MPa,with epoxy resin adhesives as the hinder.Then,the bond strengths of the adhesives with various mass ratios of epoxy resin to hardener,namely 1:0.7,1:0.8,1:0.9 and 1:1.0,were investigated.The resuhs indicate that the bond strength reaches its maximum when the mass ratio is 1:0.8,and that,when A1 foils with their surface ground in different directions are added in the lap joints,the unidirectional grinding may result in higher bond strength.Microstructure analysis results show that the interfaces of Al₂ O₃/epoxy/Al bond tightlv. Moreover,mechanical test results show that,as compared with Al₂ O₃ monolith,the fabricated composites haye a slightly lower bending strength but much higher fracture toughness and fracture work,which is attributed to the multiple fractures occurring during the crack propagation.

Efects of Preparation Process of MQ Silicone Resin on Reinforcement of RTV Silicone Rubber

Liang Yin-xing Guo Peng Ren Bi-ye Tong Zhen

2013, 41(2):  123-128.  doi:10.3969/j.issn.1000-565X.2013.02.020

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Vinyl MQ silicone resin(M and Q respectively represent R₃SiO_1/2 and SiO_4/2)was synthesized via the hydrolytic condensation of hexamethyldisiloxane,1,3-divinyl-1,1,3,3 tetramethyldisil0xane and tetraethyl orthosi-licate,and the effects of polymerization conditions on the properties of the product were investigated.Then,a series of room-temperature vulcanizing(RTV)silicone rubbers reinforced with vinyl MQ silicone resin were prepared from vinyherminated polydimethylsiloxane(PVMS)cured with organohydrogenpolysiloxane under the catalysis of Pt cata-lyst.Finally,the effects of the preparation process on the mechanical properties and transparency of the cured sili-cone rubbers were investigated.The results show that the synthesized MQ silicone resin is of the best reinforcement effeet when HCl and ethanol contents are respectively 4.0% and 1.6% and when the M/Q molar ratio is 0.75,and that,when the mass ratio of PVMS to MQ silicone resin is 1,the molar ratio of Si-H to Si-Vi is 1.4,the catalyst dosage is 10μg/g and the inhibitor dosage is 0.3 m/g,the cured silicone rubbers are of a tensile strength being up to 7.2 MPa and of excellent transparency owing to the reinforcement of MQ silicone resin.

Efect of Semisolid Rolling on Microstructure of Deposited 7050 Aluminum Alloyh

Li Feng-xian Liu Yun-zhong Li Zhi-long Du Liang

2013, 41(2):  129-134,140.  doi:10.3969/j.issn.1000-565X.2013.02.021

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Semisolid rolling of spray-deposited 7050 aluminum alloy was carried out at 560～620 ℃,and the effects of remehing temperature on grain size and second-phase distribution of the alloy were investigated by means of SEM ,EDS and XRD.Moreover,the influences of remehing temperature and thickness reduction ratio on the mi-crostructureof the strips were explored,and the feasibility of semisolid rolling was evaluated.The results show that(1)the activation energy for the grain growth of spray-deposited 7050 aluminum alloy is 70.5 kJ/mol;(2)when the remehing temperature inereases from 560 to 620 ℃,the coarsening rate and the liquid fraction of spray-deposited 7050 aluminum a110y respectively increase from 1.16 to 76.06  μm³ /s and from 3.7% to 64.1% ;(3)the distribu。ti0n and amount 0f second-phase particles inhibit the coarsening of spray-deposited 7050 aluminum alloy; (4)the optimum remelting temperature for the semisolid rolling is 590℃ ;and(5)the rolling deformation plays its role in tenns of eliminating pores,breaking grains and accelerating dynamic reerystallization.

Absorbing Properties of Cement-Based Composites with Electromagnetic Modification by Coating

Guo Ai-li Gao Ri Ba Heng-jing

2013, 41(2):  135-140.  doi:10.3969/j.issn.1000-565X.2013.02.022

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Closed-pore perlite and fly—ash floating beads were subjected to the surface electromagnetic modification by coating,and the modified products were respectively used to prepare cement·based composites with absorbing properties. Then,the electromagnetic wave reflectivity of the composites was measured,and a suitable proportion of the materials used for coating was determined to obtain composites with stable absorbing properties.Moreover,the electromagnetic wave refleetivity of the cement-based composites respectively with modified perlite and graphite(or ferrite)in S~C and X~Ku wavebands was comparatively investigated,and the microstructure of the modified per-lite was finally observed by means of SEM.The results show that graphite and ferrite,which are uniformly distribu-ted on the closed-pore perlite surface with a alternately-distributed continuous glaze surface and a special honey-comb structure,form a resonant absorber with high performance,and that the closed-pore perlite modified by coa-ting effectively improves the absorbing properties of cement—based composites and broadens the -10 dB bandwidth.

Nickel Release Rate of BZn10-25 Nickel Silver Used for Jewelry Manufacturing

Yuan Jun-ping Li Wei

2013, 41(2):  141-146.  doi:10.3969/j.issn.1000-565X.2013.02.023

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With the extensive use o nickel silver in jewelry manufacturing,the nickel release rate of this material has become a universal concern for jewelry industry and consumers.In this paper,BZn10-25 nickel silver was cho-senas the experimental material,and its nickel release rates under different conditions were tested according to the EN1811 standard.The results show that(1)the heat and surface treatment methods significantly affect the nickel release rate;(2)the sandblasting surface with 100-mesh quartz sand and the polishing surface under high-tempera-ture quenching are both of the highest nickel release rate,while the polishing surface under medium-temperature tempering is of the lowest rate;and(3)no matter what condition there is,the nickel release rate of BZn10-25 nickel silver is far more than the limit specified by the Nickel Directive,which means that the jewelry made with this material is likely to cause nickel allergy.