Table of Content

25 December 2011, Volume 39 Issue 12

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Electronics, Communication & Automation Technology

Fast Source Camera Identification Based on Sign Information of Components of Pattern Noise

Hu Yong-jian Lai Zhi-mao Liu Bei-bei

2011, 39(12):  1-6. 

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In the existing source camera identification methods based on the PRNU ( Photo Response Non-Uniformity) pattern noise of sensors,brute-force search schemes,namely exhaustive schemes,are commonly employed,which may result in low identification efficiency when there exist many long camera fingerprints. In order to solve this problem,a fast source camera identification algorithm is proposed based on the sign information of the components of pattern noise. In this method,compact camera fingerprints are constructed by using the large-magnitude components of pattern noise,and a separate-chaining Hash table is employed to store the information of reference fingerprints. Then,candidate reference fingerprints are permuted based on the number of the components with the same sign between the test and the reference fingerprints. According to the order of reference fingerprints,the correlation detection can be successfully implemented. Experimental results show that the proposed method greatly
lightens the computational burden.

Bi-Directional Motion-Compensated Reconstruction Algorithm for Pixel-Domain Distributed Video Coding

Yang Chun-ling Su Zhuo-han

2011, 39(12):  7-12. 

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In order to improve the objective and subjective quality of the decoded videos in distributed video coding ( DVC) systems,a bi-directional motion-compensated reconstruction ( BMCR) algorithm is proposed for the pixeldomain DVC. In this algorithm,the correlation between intra-frame and inter-frame videos is fully considered,and the pixels whose side information falls in the decoded quantization bins are directly reconstructed according to the side information values,while the pixels whose side information falls out of the decoded quantization bins are reasonably reconstructed by the bi-directional motion compensation with quantization bins. Experimental results indicate that,as compared with the commonly-used MMSE ( Minimum Mean Square Error) reconstruction algorithm,BMCR algorithm achieves an average PSNR increment of about 0.5 dB and effectively improves the visual quality of the decoded videos for the middle-and high-speed motion sequences in the Wyner-Ziv video coding system.

Medical Image Fusion Based on Shift-Invariant Shearlet Transformation

Wang Lei Li Bin Tian Lian-fang

2011, 39(12):  13-19. 

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In the conventional shearlet transformation-based image fusion methods,there commonly exists a pseudo-Gibbs phenomenon at the singularities of the fused image. In order to solve this problem,a new fusion method of medical images is proposed based on the shift-invariant shearlet transformation. In this method,source images are decomposed into lowpass and highpass sub-bands via the shift-invariant shearlet transformation. Then,the lowpass coefficients are combined by employing the scheme based on the region coefficients’absolute values and weights,and the highpass sub-bands are merged by adopting a fusion scheme based on the support vector value-motivated self-generating neural network ( SGNN). Finally,the fused image is obtained via the inverse shift-invariant shearlet transformation. Both the visual comparison and the quantitative analysis show that the proposed method effectively avoids the pseudo-Gibbs phenomenon and outperforms the conventional wavelet-based,contourlet-based and nonsubsampled contourlet-based methods in terms of entropy,mutual information,average gradient and QAB/F.

Combined Relay Selection and Power Control Algorithm Based on Interference Avoidance

Hu Jie Feng Sui-li Lu Dan-song

2011, 39(12):  20-24,31. 

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In order to eliminate extra interferences during the relay transmission in large-scale wireless networks,a combined relay selection and power control algorithm is proposed based on the interference model. In this algorithm,with the help of the defined interference coefficient and the interference list for the relay node,the relay with the maximum interference coefficient is selected to adjust the power of the relay in each iteration. Thus,a noninterference relay with the largest capacity is obtained. Simulated results indicate that,as compared with the relay selection algorithm without interference consideration or with interference avoidance,the proposed algorithm possesses larger network capacity and is more effective when there is serious interference.

Combined Selection of Users and Antennas During Coordinated Precoding of Base Station

Sun Li-nan Zhang Zhong-zhao Sha Xue-jun

2011, 39(12):  25-31. 

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In the coordinated precoding of base station,the number of supported users is commonly limited by that of antennas,so that a selection of users is required. In addition,for the purpose of further reducing the interference to other users,a selection of antennas can also be performed. Based on the two above-mentioned details,two lowcomplexity and near-optimal combined selection algorithms of users and antennas in base-station coordinated systems are proposed to maximize the system sum capacity. The two algorithms,respectively based on capacity and norm,both adopt the greedy principle to simultaneously select users and antennas. Simulated results show that,when the number of users in the system approaches the precoding constraints,only the antenna selection can be used,and the system performance is even better than that before the antenna selection; and that,when there exist a great number of users in the system,the combined selection can be used,which may achieve multi-user diversity gain resulting from user selection as well as additional performance gain for the users without antenna selection but with the same antenna number.

Adaptive Backstepping Sliding Mode Control of Uncertain Nonholonomic AGV

Ye Jin-hua Li Di Ye Feng Lai Yi-zong

2011, 39(12):  32-37,43. 

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Proposed in this paper is a trajectory tracking control scheme of ( 2,0) -type nonholonomic AGV ( Automated Guided Vehicle) . In this scheme,the complex nonlinear dynamic system of AGV is taken into consideration,and the standard input-output nonlinear feedback control is employed to linearize the system. Moreover,in order to overcome the model parameter uncertainty and external unknown disturbances of the AGV,a general uncertain dynamic model of AGV with the output from the actuator is established,and a position servo compensation using an adaptive backstepping sliding mode controller based on the Lyapunov stability theorem is implemented,which ensures the stability and asymptotic convergence of the system. Simulated results show that the proposed scheme not only weakens the chattering during the sliding mode control but also eliminates the impacts of model uncertainty and external disturbances on the system,so that it helps to track the desired trajectory for AGV rapialy and accurately.

Crackle Feature Extraction Based on Fractional Hilbert Transform

Li Zhen-zhen Du Ming-hui Wu Xiao-ming

2011, 39(12):  38-43. 

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As the existing methods to detect crackles are of non-ideal detection effects and complex computation,a new method taking the advantage of high sensitivity of fractional Hilbert transform to the abnormal components of signals is proposed. In this method,for different fractional values,Hilbert transforms are employed to transform crackle signals into the signals with stepped phase shifts. Then,functions describing the correlation between the original lung sound signals and the transformed ones are obtained with respect to different fractional orders,which are considered as the features to be matched with standard templates. The detected signals with high matching coefficients are judged as crackles,while those with low matching coefficients are judged as non-crackles. Simulated results indicate that the proposed method is effective and the detection accuracy is up to 91.2%.

Computer Science & Technology

Bialgebraic Structure of Abstract Data Types

Su Jin-dian Yu Shan-shan

2011, 39(12):  44-50. 

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As algebraic or coalgebraic methods have some disadvantages in analyzing the relationships and properties between the syntactic constructions and the dynamic behaviors of abstract data types,this paper presents a bialgebraic structure of abstract data types based on the category theory and the distributive laws,usesλ -bialgebras to naturally describe the transformation between the syntactic constructions and the dynamic behaviors,and employs distributive laws to functorially lift coalgebraic and algebraic functors,thus lifting initial algebras ( or final coalgebras) to initial ( or final)λ -bialgebra. Moreover,the functorial lifting is applied to the definition and computation of recursive and corecursive functions. Case study indicates that,as the functorial lifting extends the inductive principles of algebras and the coinductive principles of coalgebras,it helps to improve the abilities of programming languages in describing or proving the properties of abstract data types.

Correction Algorithm of Matching Error for DIBR

Zhang Ling Tai Guo-qin Liu Ran Xie Hui Xu Xiao-yan

2011, 39(12):  51-55. 

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Due to the variability in virtual visibility,the imprecise depth image and the inaccurate calculation,matching errors may occur in the virtual views synthesized by DIBR ( Depth Image-Based Rendering) techniques. In order to solve this problem,a matching error correction algorithm named Zero-Cross Correction ( ZCC) is proposed based on the order matching constraint. ZCC determines the matching error region by analyzing the mapping
relations between the pixel points in the destination image and the corresponding matching points in the reference image,and it assigns the matching points of all points in the matching error region to the matching points of the starting point in the same region,thus successfully implementing the correction of matching error. Experimental results indicate that the proposed algorithm is effective in eliminating matching errors and that it can be applied as an additional error detection and correction algorithm to the postprocessing of novel views generated by DIBR because it is totally independent of the 3D image wraping in DIBR.

Texture Segmentation Based on Complementary Feature Extraction of Wavelet Packet Frame Sub-Band

Wang Qing-xiang Li Di Zhang Wu-jie Ye Feng

2011, 39(12):  56-62. 

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As multi-texture images are difficult to segment accurately,this paper proposes a texture segmentation method based on the complementary feature extraction of wavelet packet frame sub-band. In this method,first,the original texture image is decomposed by using the wavelet packet frame. Then,two sets of features in the neighborhood window of each pixel,namely,the average absolute deviation of sub-band coefficients and the mean and
standard deviation of the histogram of oriented gradients for sub-band coefficients,are extracted for each sub-band coefficient. Moreover,texture pixels are clustered via the improved spatial fuzzy c-means clustering. As the proposed method takes into consideration the spatial distribution of the local standard deviation of pixel feature values,it helps to obtain texture segmentation results with low misclassification rate of pixels near the texture boundary. Finally,several texture images from Brodatz album are used to test the proposed method. Fisher linear discriminant analysis indicates that the combination of the two sets of features is more effective in texture distinction than any single feature. Texture segmentation experiments show that the proposed segmentation scheme helps to achieve higher segmentation accuracy. In addition,test results of algorithm speed prove that the proposed method is applicable.

Vehicle Shadow Elimination Based on Multi-Point Pair Reference Model

Qi Qi-feng Wu Xin-sheng Deng Jun

2011, 39(12):  63-69. 

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In order to eliminate the shadow interference in a vehicle detection process,a stable multi-point pair reference model based on point pair properties,which is insensitive to the environment,is established in the global domain of the image. This model takes advantage of the hue and the luminance among the foreground,the background and the moving shadow in HSL color space and adopts the offline training method in a given background image set. By fully considering the color information of the whole image,the model reduces the error of background pixels,online
eliminates the impact of moving shadow on vehicle segmentation and strongly inhibits the moving background and illumination change in complex environments. Moreover,to simplify the computation of the proposed algorithm,background templates are introduced,which greatly reduces the number of operation pixels and improves the segmentation efficiency. Simulated results indicate that,as compared with the other vehicle shadow elimination methods,the proposed algorithm based on the multi-point pair reference model is more accurate and robust.

Online Diversified Ranking Algorithm Based on Clustering and User Clicks

Ma Qian-li Lin Gu-li

2011, 39(12):  70-74,99. 

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In the information retrieval on the Internet,diversified ranking methods are used to provide top diverse results for users. This paper proposes an online diversified ranking algorithm CRBA based on clustering and user clicks. CRBA utilizes the similarity of documents to user feedbacks and provides diverse ranking results according to the continuous interaction of users. With the combination of the online method and the offline one,CRBA takes advantage of the topic clustering so that the convergence can be speeded up by preliminarily dividing candidate documents according to their topics. Moreover,it utilizes the merits of online ranking algorithms so that more accurate and complete estimation of users' purposes can be obtained from user clicks. Experimental results show that,as compared with the other online diversified ranking algorithms,CRBA converges more quickly and adapts well to the ranking of documents with a large amount.

Service-Oriented Collaborative Design Platform for Cloud Manufacturing

Zhang Qian Qi De-yu

2011, 39(12):  75-81. 

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In order to support complex and large-scale collaborative design and implement high-level sharing of manufacturing resources and capability,the concept of cloud manufacturing,as well as the characteristics of the collaborative design platform based on cloud manufacturing,is discussed. Based on the service-oriented architecture and Web services technologies,the framework of a service-oriented,loose and open collaborative design platform
for cloud manufacturing is constructed and is then described and analyzed by using five-dimension views. Moreover,such key technologies as the service-oriented architecture,the resource management,the intelligent matching and combination of resource services,the virtualization,the dynamic monitoring and the conflict resolution are analyzed. Both the running mode of the platform and the collaborative design process in virtual collaborative design environment show that the proposed platform is applicable.

DRQS_HCT Agent-Supported Trust Cooperation in Open Environments

Zhou You-ming Gao Ji Fu Zhao-yang

2011, 39(12):  82-89. 

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Proposed in this paper is a DRQSHCTAgent model to reduce the risks caused by agents’contract violations. In this model,multiple schemes of the task are obtained by introducing service compositions and recipes; a direct credit is defined in terms of the moral and the service credits; the concealing of the service credit is uncovered by defining multiple service credits; the shortcomings of individual chain recommendation are overcome by the group recommendation; and the solving schemes are selected and optimized by calculating the scheme credit. The proposed model improves the rationality and maneuverability of the credit calculation with the help of contract samples,and ensures the self-organizing cooperation credibility and the system reliability due to the contract-based constraints. Both the design instance and the experiment indicate that the proposed model is more suitable for the resolution of trust cooperation problem in open environments.

Physics

Relationship Between Secondary Electron Emission Characteristic and Triboelectrification of Solid Materials

Chang Tian-hai Ma Wei Chang Jian

2011, 39(12):  90-93. 

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In order to reveal the relationship between the secondary electron emission characteristic and the triboelectrification of solid materials,the electrostatic list regulated by some related standards or reported by the literature both at home and abroad was taken into consideration,and several solid materials located at the end of the electrostatic list,namely,polytetrafluoroethene,high-density polyethylene ( HDPE) ,polypropylene ( PP) ,polyvinyl
chloride polymer ( PVC) and A3 carbon steel,were selected to carry out triboelectrification experiments. By focusing the secondary electron emission characteristics of the solid materials,the relationship between the primary incident energy and the rubbing speed as well as the friction force during the electrostatic electrification was revealed,and the occurrence of positive surface electrostatic potential after the rubbing of solid materials with A3 carbon steel was analyzed. Experimental results indicate that the positive surface electrostatic potential results from the secondary electron emission characteristic of solid materials,which means that there exists a strong correlation between the secondary electron emission characteristic and the electrostatic electrification process of solid materials.

Error of Near-Field HRTF Measured by Using Spherical Dodecahedral Sound Source

Yu Guang-zheng Chen Ze-wei

2011, 39(12):  94-99. 

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In this paper,first,a combined model consisting of a spherical dodecahedral sound source and a spherical head model is established. Then,the binaural pressure and near-field head-related transfer function ( HRTF) are calculated via the multipole expansion of spherical harmonic functions and the rotation transform of spherical basis functions. Moreover,the common influences of the directivity and multiple scattering of the spherical dodecahedral sound source on the near-field HRTF measurement are analyzed according to the magnitude spectrum errors of HRTF. The results show that ( 1) the effects of sound source on near-field HRTF measurement weakens with the decrease in sound source radius and with the increase in half scan angle of each local pulsating unit; ( 2) when the sound source distance is not less than 0. 2m,the sound source radius is not more than 0. 025 m and the half scan angle is not less than 23. 6°,the errors resulting from the source generally appear at the frequencies more than 12 kHz; ( 3) except for some contralateral directions,the errors of HRTF are controlled within ± 3. 5dB,which basically satisfies the requirements of the near-field HRTF measurement. The proposed method is finally proved valid and applicable by the data measured in some particular directions with the help of a self-fabricated wood sphere and a practical spherical dodecahedron sound source.

Accuracy Analysis and Verification of Virtual Sound Source Position Reported by Tracker

Zhang Cheng-yun Xie Bo-sun

2011, 39(12):  100-104,126. 

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The localization of virtual sound sources is an important approach to evaluating the performance of a virtual auditory display. This paper proposes a method to report the direction and distance of the perceived virtual source position using a tracker,and implements the method with computer software. The proposed method is then verified by experiments,with good repeatability of the reported position being achieved. With this method,the
standard deviations of distance,horizontal angle and elevation obtained from six measurements for fifteen positions respectively reach 0. 4 cm,0. 6° and 0. 5°. The variance analysis with a significance level of 0. 05 also indicates that the reported position is correct and reliable. Finally,the method is applied to practical virtual sound source localization. The results show that the proposed method,which is simpler than the conventional oral reporting method,helps to obtain localization results with low discreteness,especially for the reporting of distance; and that,with the help of the method,the judgment response time,which is the average of stable and dynamic judgment time,decreases from 19. 8 s to 7. 2 s. It is thus concluded that the proposed method can effectively reduce the difficulty and workload in the localization experiment of virtual sound sources.

Food Science & Technology

Dynamic Monitoring of Gelatinization Process of Starch Based on Digital Image Analysis Technique

Gao Qun-yu Xie Qin

2011, 39(12):  105-109. 

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In order to overcome the difficulty of the original polarizing microscope-based method in monitoring the gelatinization of starch,a new method to dynamically monitor the gelatinization process,namely the integral optical density-based method,is proposed. In this method,the gradual disappearance of the birefringence light of starch granules under polarized light is taken into consideration,and the digital image analysis technique is used to analyze the integral optical density of the acquired real-time digital image of the gelatinization,thus obtaining the gelatinization degree. Then,the proposed method is compared with three traditional methods for gelatinization degree detection. The results show that ( 1) the gelatinization degree detected by the proposed method is the highest due to the response of the method to partial gelatinized starch; ( 2) there is a quantitative relationship between the disappearance of starch crystal structure detected by the proposed method and the thermal change detected by DSC during
the gelatinization; ( 3) there are not only difference but also correlation between the gelatinization degrees detected by the proposed method and by the DSC; and ( 4) the real-time date obtained by the proposed method well reflect the real state of starch during the gelatinization.

Composition and Antitumor Activity of Polysaccharides from Sarcodon imbricatus

Chen Jian Zhang Ling-zhi Wei Ding Xu Xiao-fei

2011, 39(12):  110-114. 

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Two kinds of polysaccharides,namely SIPa and SIPb,were obtained from the fruit body of Sarcodon imbricatus via isolation and purification. Then,the IR spectra of the products were investigated,and the relative molecular mass and monosaccharide composition of each product were determined by means of high-performance gel permeation chromatography and gas chromatography. Moreover,the antitumor activities of the two products were
evaluated by means of the MTT method. The results show that ( 1) SIPa and SIPb both possess typical infrared absorptions of polysaccharides; ( 2) the sugar chain of SIPa is mainly β-configuration pyranoside; ( 3) the weightaverage relative molecular mass of SIPa and SIPb are respectively 2. 12 × 10⁵ and 1. 05 × 10⁴ ; ( 4) SIPa is a kind of glucan while SIPb is a kind of heteroglycan containing fucose,mannose,glucose and galactose in a molar ratio of 8. 93: 1: 4. 25: 29. 18; and ( 5) both SIPa and SIPb remarkably inhibit the growth of human liver cancer cell line Hep G2 and human ovarian cancer cell line HO-8910 in a dose-dependent manner.

Preparation and Controlled Release Property of Soy Protein /κ-Carrageenan Cold-Set Gels

Yang Xiao-quan Zhou Xiao-ling Wang Xiao-yuan Yin Shou-wei

2011, 39(12):  115-120. 

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In order to construct edible conveying carriers with excellent controlled release properties,soy protein /κ-carrageenan mixed cold-set gels were produced via the crosslinking of microbial transglutaminase ( MTGase) . Then,the microstructure and rheological properties of the mixed gels were analyzed,and the tablets flaked by the gels via the freeze-drying were used as the controlled release carriers for riboflavin to investigate the release properties and the release dynamics in simulated gastrointestinal fluid. The results show that ( 1) the mixed gels are structurally in dense network; ( 2) κ-carrageenan improves the strength and hardness of the mixed gels,while riboflavin weakens the gel properties; ( 3) in simulated gastrointestinal condition,the one-hour accumulative release rate of the gels and the tablets for riboflavin in simulated gastric fluid is lower than 17% but ranges from 75% to 100% after a moving to simulated intestinal fluid for 9h,which means that both the gels and the tablets have sustained release
effect for riboflavin. In addition,it is found that the release mechanisms of riboflavin in simulated gastric and intestinal fluids are different from each other; specifically,one is controlled by Fick diffusion while the other is by non-Fick diffusion.

Covalent Modification of SPI by Dextran in Macromolecular Crowding Conditions

Qi Jun-ru Zhuo Xiu-ying Yang Xiao-quan Yin Shou-wei Huang Li-xin

2011, 39(12):  121-126. 

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In order to explore the covalent modification of proteins by polysaccharide chains,soy protein isolate ( SPI) -dextran conjugate ( SDC) was prepared via the Maillard reaction in macromolecular crowding conditions. Then,the functions and conformation of the product were analyzed by means of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis,the fluorescence spectroscopy,the gel permeation chromatography and the circular dichroism spectroscopy. The results show that ( 1) there occurs a covalent binding of dextran to SPI after the Maillard reaction best being carried out with a SPI-to-dextran mass ratio of 1: 1 at 60℃ for 30 h; ( 2) as compared with the SPI-dextran mixture without the Maillard reaction,SDC possesses less hydrophobic groups on its surface and stronger emulsifying activity in macromolecular crowding conditions; ( 3) SDC is more thermally stable than SPI; and ( 4) the covalent binding of polysaccharides changes the structure of SPI and improves the structural flexibility,which benefits the function display of SPI.

Effect of Pulsed Electric Field on Esterification of Lactic Acid and Ethanol

Zeng Xin-an Liu Xin-yu

2011, 39(12):  127-131. 

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Pulsed electric field ( PEF) was used to enhance the esterification of lactic acid and ethanol,and the influences of electric field strength,temperature and system moisture on the esterification were analyzed. Then,the variation of activation energy during the esterification was explored. The results indicate that ( 1) when the reaction performs with a flowrate of 50 mL /min at 30 ℃,the enhancement by PEF in a certain duration becomes stronger
with the increase in electric field strength; ( 2) by applying 25 kV/cm PEF to the system for 10 h,the production of ethyl lactate is 2. 1 times that of the production without PEF irradiation; ( 3) by applying 20kV/cm PEF for 10h at 25,30 and 35℃,the productions of ethyl lactate are respectively 1. 7,1. 8 and 1. 4 times that of the productions without PEF irradiation; ( 4) PEF treatment is more effective for the system containing water; and ( 5) by applying
20kV/ cm PEF to the esterification system,the activation energy significantly decreases from the original 43. 43kJ /mol to 25. 05 kJ /mol and the stage esterification is a zero-order reaction. The above-mentioned findings indicate that PEF treatment is a promising technique to enhance chemical reaction under non-catalytic condition at room temperature.

Architecture & Civil Engineering

Analysis of Relationship Between Local and Global Ductility Demands of Multi-Rise Structures

Zhou Jing Fang Xiao-dan

2011, 39(12):  132-137. 

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Based on a reasonable assumption of modeled structures,simplified analytical relationships between global ductility demands and local-storey ductility demands,as well as between local-storey ductility demands and vertical element ductility demands,are derived by theoretical analysis for multi-rise structures. Both the most unfavorable analytical relationship and the numerical results indicate that ( 1) the local ductility demand of the weak storey is larger than the global one and increases owing to any additional storey; ( 2) the post-yield stiffness of storey greatly influences the relationship between the local and the global ductility demands; ( 3) the relationship between the soft-weak column element and the local storey ductility demands correlates with the lateral stiffness ratio and the yield strength ratio of the strong column to the weak column; and ( 4) the ductility demand of the soft-weak column ( the lower limit) decreases with the increase in the stiffness ratio but increases ( the upper limit) with the yield strength ratio.

Seismic Behaviors of SRC Beam Transfer Structure with Energy Dissipation Haunch Braces

Yang Chun Wu Yi He Ming-ji Zheng Jun-guang Zhang Chun-mei

2011, 39(12):  138-143,164. 

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In order to avoid serious damage at the transfer storey of a transfer structure in earthquake,energy dissipation haunch braces ( EDHBs) were used to strengthen the transfer structure,and the SRC ( Steel-Reinforced Concrete) transfer frame structures with and without EDHBs were tested under cyclic loading. The results show that ( 1) reasonably-designed frame structure with EDHBs is effective in controlling the crack development of the transfer
beam; ( 2) with the setting of EDHBs,the initial stiffness of the transfer structure improves,and the bearing capacity,the ductility coefficient,the hysteretic energy dissipation and the equivalent viscosity coefficient respectively increase by 10.9%,77.1%,93.1% and 107%; and ( 3) EDHBs not only strengthen the damaged transfer storey but also improve the seismic behaviors of the transfer structure. In addition,by comparing the test results with those obtained from the proposed fine finite element model of the SRC transfer structure with EDHBs,it is found that the proposed model is accurate enough for the subsequent finite element analysis of the structure with EDHBs.

IDA-Based Seismic Fragility Analysis of Transfer Frame with Energy Dissipation Haunch Braces

He Ming-ji Wu Yi Cai Jian Huang Yan-sheng Yang Chun

2011, 39(12):  144-151. 

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Based on the incremental dynamic analysis ( IDA) ,the seismic fragility of RC ( Reinforced Concrete) transfer frame structures with and without energy dissipation haunch braces ( EDHBs) was investigated,and the corresponding fragility curve equations were established. The seismic reliability of the structure with EDHBs was then evaluated,and the influences of buckling-restrained EDHBs on the failure mechanism of the structure were analyzed. The results show that,by setting buckling-restrained EDHBs,the exceeding probability of the RC transfer frame structure in different damage states decreases by 5% ～ 80%; and that EDHBs change the soft-storey failure mechanism at the transfer storey and the neighboring stories and effectively alleviate the damage of transfer components,thus preventing the structure from global and local collapses. In addition,as EDHBs may result in large additional shear force on the RC column,steel-concrete composite components are more feasible in constructing steelreinforced concrete transfer structures with EDHBs.

Analysis of Formation of Spoke-Shaped Cable-Strut System with Synergistic Effect of Column-Beam Structures

Zhao Jun-zhao Chen Wu-jun Pan Qin Fu Gong-yi

2011, 39(12):  152-158. 

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Aiming at the tension forming of a spoke-shaped tensile cable-strut assembly,which is an important step of the assembly construction,an analytical parabolic element was adopted to simulate the cable based on the unstressed cable length and the structural topology,and a nodal unbalanced force vector was formulated with the equilibrium matrix of the pin-jointed cable-strut system. Then,on the basis of the finite-element nodal equilibrium
equation and by considering the continuous and compatible constrained linear displacement and the boundary constraints,the global stiffness matrix was described in a sector form,and a united nodal unbalanced force formula was thus deduced for the perimetric beam-column-cable joints,which only takes into consideration 3 linear degrees of freedom. Moreover,a nonlinear iterative resolution was performed via the dynamic relaxation for the deduced formula,and the proposed algorithm was implemented by programming. Finally,a case study on the tension forming of the tensile cable-strut canopy of Shenzhen Baoan Stadium was carried out with the proposed algorithm. The results indicate that ( 1) the proposed algorithm is effective in analyzing the tension forming; ( 2) the parabolic element is more accurate in cable simulation than the link element; and ( 3) the synergistic effects of perimetric column-beam structures cannot be neglected during the simulation of integral tension forming.

Mechanical Properties of Double-Cable Suspension Bridge System ( Ⅰ)

Chai Sheng-bo Xiao Ru-cheng Sun Bin

2011, 39(12):  159-164. 

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This paper deals with the basic mechanical properties of a double-cable suspension bridge system that has wide application prospect in multi-tower suspension bridges. In the investigation,the distribution of uniform loads on the top and the bottom cables are analyzed when the span is fully and uniformly loaded,and the vertical stiffness of the main cable is formulated. The results indicate that the distribution of uniform loads on the top and
the bottom cables depends on the section parameters of the cables and the rise-span ratio and that the vertical stiffness of the main cable under uniform loads increases with the rise-span ratio. Based on the above-mentioned findings,the girder deflection resulting from the cable extension is obtained. In addition,the deformations of the discussed double-cable system respectively due to concentrated loads and uniform loads on the half span are analyzed,and the results are verified by using a finite element model,with good accordance being obtained.