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    • 1  A Chinese Short Text Similarity Algorithm Based on Semantic and Syntax
    LIAO Zhi-fang ,  ZHOU Guo-en ,  LI Jun-feng ,  LIU Fei ,  CAI Fei
    2016, 43(2):135-140.
    [Abstract](2537) [HTML](0) [PDF 762.94 K](5556)
    Abstract:
    A short text algorithm based on semantic and syntax by analyzing the characteristics of Chinese short text was proposed.The algorithm combines semantic similarity with the similarity of sentence syntax in Chinese short text, that is to say, to calculate the similarity of short text with the same syntax structure and consider the contribution with sentence words order to similarity.The experiments show that the proposed algorithm is closer to people's judgment and gets a better precision rate and recall rate in the aspect of Chinese short text similarity calculation results.
    2  Effect of Short-wavelength Components in Rail Irregularity on the Coupled Dynamic Responses of Train and Simple-supported Bridge
    ZHU Zhi-hui ,  WANG Li-dong ,  YANG Le ,  YU Zhi-wu
    2016, 43(1):53-60.
    [Abstract](897) [HTML](0) [PDF 2.41 M](4734)
    Abstract:
    As an important excitation source, track irregularities have a significant effect on the running safety and riding comfort of the high-speed train and bridge. A three-dimension train-track-bridge coupled dynamic model was established to study the effect of short-wavelength components of track irregularities on the dynamic responses of the train and 32 m simple supported box-girder bridge. Five different wavelength track irregularities were generated from German low interference track spectra in numerical method. The dynamic responses of train-track-bridge coupled system under different track irregularities were calculated. The results have shown that the 1 m short-wavelength component in track irregularities can significantly amplify the wheel-rail force, offload coefficient, derailment coefficient and the mid-span acceleration of the bridge. The mid-span displacement of the bridge, the wheel-rail relative lateral displacement and the car-body acceleration are less affected by the short-wavelength component of track irregularities. The main reason for the offload coefficient exceeding the code limits is 1~2 m short-wavelength components of track irregularities. The reduction of the short wavelength track irregularities component is effective in increasing the running safety.
    3  Investigation of the Wind Field Characteristics on Isolated Hill and Two Adjacent Hills Using CFD Numerical Simulation
    SHEN Guo-hui ,  YAO Dan ,  LOU Wen-juan ,  XING Yue-long ,  PAN Feng ,  GUO Yong
    2016, 43(1):37-44.
    [Abstract](1185) [HTML](0) [PDF 5.83 M](4729)
    Abstract:
    CFD numerical simulation method was employed to study the wind field characteristics of three-dimensional hills under isolated hill and two adjacent hills condition. The influence of the calculation model surface roughness on the wind field was studied. The wind fields on isolated hill with different slopes were calculated. The wind fields of two adjacent hills in left-right arrangement were also investigated, and the influence of the hill slope, wind azimuth and hill distance on the wind field was studied. The results show that, if the model surface roughness increases, the speedup effect of half hill height above the top of the hill decreases and the height of vortex region increases. The speedup effects on the cross-wind plane of an isolated hill are more significant than those on the along-wind plane, and the most unfavorable position ranges from the half hill height to the top of the hill on the cross-wind plane. When two adjacent hills are in left-right arrangement with zero distance, the speedup ratios on the front hill are larger than those on the rear hill under yawed azimuth, and the speedup ratio, when wind blows perpendicularly to the two hills, is between these two data.
    4  A Hybrid Power Conditioner for High-speed Electric Railway and Its Power Capacity Analysis
    XU Jia-zhu，LI Ping ,  HU Si-jia ,  DONG Xin-xiao ,  ZHOU Guan-dong ,  CHEN Yue-hui
    2016, 43(4):89-97.
    [Abstract](1162) [HTML](0) [PDF 3.25 M](4632)
    Abstract:
    With wide application of AC drive electric locomotives in railway networks, the negative sequence current and neutral section increase significantly, and the co-phase power supply system with Railway Power Conditioner (RPC) is an effective solution. In order to increase its cost performance, a new Hybrid Railway Power Conditioner(HRPC) for co-phase was proposed. Compared with the traditional RPC, HRPC is much lower than RPC in operation voltage, so its capacity of active part decreases significantly. This paper analyzed its topology, compensation principle and operation voltage of its active part. The design of its key parameter was given. The results prove that HRPC is lower by 46%~50% than that of RPC in completing similar compensational tasks through simulation.
    5  Experimental Research and Finite Element Analysis of the Interfacial Bonding Behavior of CFRP-Concrete Interface
    SHANG Shou-ping ,  LI Zhi-bing ,  ,  PENG Hui
    2014, 41(6):43-51.
    [Abstract](2307) [HTML](0) [PDF 1.90 M](4419)
    Abstract:
    The bonding behavior of CFRP-Concrete Interface is a key performance of concrete structure strengthened with CFRP plate, and it has a critical effect on the mechanical behavior and the failure mode of the strengthened structure. This paper adopted double-shear tests on 4 concrete components strengthened with CFRP plate to investigate the mechanical behavior and the failure mode of the specimens with different bond length and to analyze the influence of different bond lengths on the ultimate capacity and the distribution of the bonding stress. According to the test results, the distribution of the CFRP strain along the bond length shows an exponential decreasing law, and the stress near the loading position is much greater than the other end. The orthotropic spring elements were adopted to simulate the adhesive layer with ANSYS software, and the finite element model of the specimen was established. The local bond slip curve obtained from the test was used as the F-d curve of spring elements. The FEA results agree with the experimental ones, confirming the correctness of the FEM. Based on the bond slip curves obtained from the test, some bond-slip constitutive relationships were fitted according to several classic bond-slip constitutive relations. The test and FEA results show that the CFRP plate has begun peeling from the concrete surface when the tensile stress applied to CFRP reaches 24% of the tensile strength of the material. To ensure the full utilization of CFRP strength, the anchorage for CFRP plate should be adopted.
    6  Algorithm of Medical Image Reversible Data Hiding for Contrast Enhancement
    OU Bo，JIANG Xiyuan，XIONG Jianqin
    2022, 49(4):26-34.
    [Abstract](869) [HTML](0) [PDF 5.89 M](4130)
    Abstract:
    Reversible data hiding for medical image contrast enhancement can not only store patient information imperceptibly, but also improve image contrast quality to facilitate the accurate diagnosis in the remote medical affairs. In this paper, a new reversible data hiding algorithm for medical image contrast enhancement is proposed. The medical image is segmented by the superpixel algorithm, and then the modifications on the region of the interest (ROI) of the image are optimized. Since the image is divided into blocks, the embedded regions can be selectively modified block by block according to their statistical characteristics. Subsequently, the modification of each pixel block applies the classical histogram modification manner, and embeds the payload into multiple embedding points at one time. We take the histogram equalization as the optimization goal, and then reduce the embedding distortion in the process of contrast enhancement. Experimental results show that when compared with the state-of-the-art methods, the proposed method is reversible and can improve the visual quality of medical images in terms of contrast enhancement.
    7  Actuator Placement Optimization for Spatial Truss Structure Based on Modal Damping Index
    WAN Huaping，，MA Qiang，，XUE Yu，，HU Penghua，，GE Huibin，，LUO Yaozhi，?
    2024(7):1-9.
    [Abstract](210) [HTML](0) [PDF 10.72 M](3892)
    Abstract:
    In order to obtain actuator placement optimization for the spatial truss stucture，this paper constructs the active vibration control system of spatial truss structure based on linear quadratic regulator （LQR） optimal controller theory， and maximizing the modal damping of the target control mode is proposed as the actuator placement optimization criterion. The effectiveness of the proposed method is verified by using the square pyramid space grid structure and the Levy-type cable dome structure， and the control effect and energy input are compared with those of the existing method. The comparison results show that with the increase of the number of actuators， the control effect and control energy input of the proposed method tend to stabilize faster than that of the existing method； when the number of actuators is the same or the energy input is the same， the control effect of the proposed method is better than that of the existing method.
    8  Model-Embedding based Damage Detection Method for Recurrent Neural Network
    WENG Shun，LEI Aoqi，CHEN Zhidan?，YU Hong，YAN Yongyi，YU Xingsheng
    2024(7):21-29.
    [Abstract](160) [HTML](0) [PDF 16.74 M](3880)
    Abstract:
    Currently， the majority of structure damage identification methods based on deep learning rely on deep neural networks to automatically extract damage-sensitive features of structures and achieve pattern classification recognition through the differences in features between damage states. However， these methods face challenges in the accurate quantification of damage and require a large amount of data for model training. This article proposes a damage detection method based on a model-embedding recurrent neural network （MERNN）. Firstly， a data-driven convolutional neural network was used to establish the mapping relationship between load and response. Then， the traditional recurrent neural network was improved using the Runge-Kutta method to create a numerical computing unit based on the recurrent neural network architecture. Finally， based on the loss function composed of the residual errors between measured responses and computed responses， the structural stiffness parameters were updated with the automatic differentiation mechanism of the neural network to achieve structural damage identification. Damage identification results of a numerical three-layer frame and a laboratory-scale shear-type frame indicate that the proposed method can accurately quantify structural damage based on the limited amount of response datas.
    9  Study on Dynamic Characteristics of Bending Damaged RC/PC Bridges Based on Concrete Damage Plasticity Models
    CHEN Zhiwei，SHI Yu，ZHANG Yao?
    2024(7):50-61.
    [Abstract](139) [HTML](0) [PDF 24.61 M](3879)
    Abstract:
    Based on the concrete damage plasticity model， the dynamic characteristics of bending damaged RC/PC bridges are investigated through numerical simulations in this paper. Firstly， a FE model generation framework was proposed to conduct the nonlinear vibration analysis of RC/PC bridges. Then， the constructed FE model was validated by comparison with experimental results from bending failure tests on simply supported RC beams. Finally， a 3D FE model of a 3-span PC continuous girder bridge from the Xiamen Bus Rapid Transit was established to study the changes in frequencies and mode shapes under different bending damage levels. It can be observed from the results that the dynamic characteristics of RC/PC bridges with bending damage change to varying degrees as the damage increases. The small vibration of the damaged bridge with concrete cracks is still linear， but the frequency decreases with the increasing vibration amplitude， indicating the nonlinear vibration. When cracks are closed， the changes in the first three frequencies and mode shapes are not significant， making it hard to identify bending damage in practice. However， when cracks are open， noticeable changes occur in the first three frequencies and mode shapes， which can serve as damage detection indicators for identification purposes.
    10  Study on Hybrid Damping Solution for Controlling Longitudinal Motion of Railway Suspension Bridge Induced by Trains
    FENG Zhouquan，，FAN Zhoujian，，JING Haokun，?，ZHANG Hongyi，， CHEN Zhengqing，，WAN Tianbao
    2024(7):10-20.
    [Abstract](150) [HTML](0) [PDF 15.59 M](3878)
    Abstract:
    A novel hybrid damping scheme was proposed to control the longitudinal motion response at the girder ends during train passage on a railway suspension bridge，utilized multiple types of dampers to control girder-end displacements to meet diverse vibration reduction requirements. With a long-span railway suspension bridge under construction as the engineering background， a detailed spatial truss model and an equivalent single beam simplified model were established. The study systematically investigates the influence of different damper parameters in the hybrid damping scheme on motion control effectiveness. The proposed solution involves installing low-exponent fluid viscous dampers longitudinally between the bridge tower and the stiffening girder. Simultaneously， eddy current dampers are installed longitudinally between the bridge abutment and the stiffening girder. Considering the unique characteristics of the bridge abutment structure， the eddy current dampers are designed as devices capable of withstanding only compressive loads and validated through prototype testing. To further enhance damping performance， the eddy current dampers are equipped with a friction energy dissipation component. This hybrid damping solution effectively controls the longitudinal motion response at the girder ends during train passage， significantly improving the safety and durability of bridge structures. The findings have significant reference value and practical implications for similar engineering projects.
    11  Sensor Anomaly Detection in Bridge Health Monitoring System Based on Gray Correlation Analysis
    WANG Xianyu，，LI Wenqi，ZHU Qiankun，，DU Yongfeng，?
    2024(7):111-118.
    [Abstract](114) [HTML](0) [PDF 16.37 M](3868)
    Abstract:
    In order to be able to detect the abnormal condition of sensors in time， a sensor abnormality detection model for bridge health monitoring system based on gray correlation analysis is designed. First， the datas collected from multiple strain sensors in normal operation and single sensor abnormality are analyzed by gray correlation analysis， respectively， and the least correlated count columns that characterize the degree of geometric similarity between each column of sensor data and the rest of the columns of data are obtained. The comparison revealed that the distribution of the least correlated counts when there was no abnormality and when there was an abnormality showed marked differences， thus verifying the feasibility of this method； then， a weight calculation strategy was designed to transform the least correlated count columns into a normalized value and use it as an evaluation index， which quantified the degree of correlation between each column of sensor datas and the rest of the columns of datas； finally， through the analysis of the evaluation indexes of multiple sets of strain datas， the multi-threshold warning mechanism was set up to realize the corresponding determination of different degrees of sensor anomalies. On another set of acceleration monitoring datas to simulate a variety of degrees of anomalies and detection， the results show an overall anomaly recognition rate of over 90%.
    12  Research on Vibration Harmonic Response Reduction of Pipelines Based on MTMD
    HE Jia，?，HU Meifei，，ZHANG Guohua，LIANG Haohua，，LI Zhangzhi，YANG Yuqiang， CHEN Zhengqing，
    2024(7):30-38.
    [Abstract](121) [HTML](0) [PDF 38.59 M](3865)
    Abstract:
    Large-scale chemical pipelines， influenced by factors such as fluid flow， boundary constraints， and source excitations， often experience vibrations during service. Unlike civil structures， these vibrations exhibit higher frequencies and may involve multiple dominant frequency components. Traditional single-frequency tuned mass dampers （TMD） struggle to achieve optimal control in this context. Meanwhile， the application of multiple tuned mass dampers （MTMD） is hindered by the challenges in determining optimal installation locations due to on-site constraints. This paper explores the mitigation of pipeline harmonic responses using MTMD. Firstly， an on-site measurement study was conducted on a propane dehydrogenation unit in a chemical plant， revealing evident frequency multiples or harmonic phenomena. Subsequently， a finite element model for local pipeline segments was established to analyze dynamic characteristics. A parameter design method for MTMD based on numerical search algorithms was proposed. Lastly， considering the limit of practical installation conditions for chemical pipelines， the impact of MTMD installation positions on vibration reduction effectiveness was investigated. Numerical results show that the vibration of pipelines can be significantly reduced by using MTMD.
    13  Hysteretic Performance of Disc Spring-Steel Tendon Self-centering Buckling-restrained Brace
    LU Junkai?，DAI Shoukun，XU Guoshan，LI Wenpeng，LI Jinping，LI Yifei，XU Xingzhe
    2024(7):83-94.
    [Abstract](116) [HTML](0) [PDF 16.41 M](3864)
    Abstract:
    The self-centering buckling-restrained brace combined both disc springs and steel tendons （DT-SCB） was proposed to solve the shortage problem of the deformation ability of the traditional self-centering buckling-restrained brace （SCBRB）. The steel tendons in series with combination disc springs are used to provide the self-centering force， and two parallel flat steel cores are responsible for dissipating seismic energy. The detailed configuration， working mechanism at different stages， and restoring force model of DT-SCB were introduced in this study. The finite element model was established， through which the effect of self-centering ratio αsc， the ratio of steel tendons and combination disc springs K1 and the ratio of self-centering unit and energy dissipation system K2 on the hysteretic behavior， self-centering level and energy dissipation capacity of DT-SCB were conducted， respectively. The results indicated that the proposed DT-SCB restoring force model agreed well with that from numerical simulation. No obvious failure characteristics were observed even if the maximum loading displacement （corresponding to the axial strain of 2.5%） was achieved. The hysteretic curve of DT-SCB was flag-shaped， with stable energy dissipation. The deformation ability of proposed DT-SCB was significantly greater than that of the conventional SCBRB with steel tendons. The maximum residual displacement sharply decreased with the increasing self-centering ratio， while the greater K1 weakened the control effect of αsc on residual deformation. The disc springs were prematurely flattened with an excessive ratio of self-centering system and energy dissipation system （K1≥2.0）， which would reduce the deformation capacity of DT-SCB. The stiffness ratio K2 had a significant influence on the energy dissipation capacity of DT-SCB， and the equivalent viscous damper ratio of DT-SCB decreased with the increase of the stiffness ratio K2. The nonlinear dynamic analysis results of the braced frame subjected to severe earthquakes showed that DT-SCB can effectively reduce the maximum and residual inter-story drifts and improve the seismic performance of the frame.
    14  Analytical of Structural Modal Parameter Identification Accuracy Based on Estimation Errors in Power Spectrum Density Transmissibility
    SUN Qian，，YAN Wangji，REN Weixin?
    2024(7):72-82.
    [Abstract](110) [HTML](0) [PDF 16.88 M](3863)
    Abstract:
    To investigate the statistical errors inherent in this classical process and its influence on PSDT measurements， based on the perturbation technique， the mean and variance of the quotient of the random variables are approximately expressed with the application of the statistical moment method. Then， the statistical moments of two response spectral estimates are substituted to derive the formulae for the mean and variance of the PSDT’s amplitude regarding the coherence function of the response and the number of averaging segments in spectrum analysis. Based on this， the error law in the amplitude of the PSDT estimate at the resonance frequency is revealed to quantify the estimation error of the mode shape. It is found that the error in the PSDT’s amplitude estimate at the resonances tends to a local minimum value， and the coefficient of variation is smaller than the counterparts of two associated response power spectrum densities. Finally， the accuracy of the derived error formulation in the paper is verified by vibration data from one numerical frame. Moreover， a parameter study regarding the influence of the selection of reference response， the time duration of measurements， and the type of window function on the PSDT and mode shape estimates is performed. The results show that using two basic responses of PSDT as the reference responses is beneficial to reduce the error in PSDT estimates and outcomes of modal analysis， and the standard variance of the estimate also decreases with the increasing time duration of measurements and finally to a specific limit.
    15  Theoretical Modeling and Eigenvalue Analysis on In-plane Vibration of Cable-Stayed Bridges
    WANG Lianhua?，XIE Xuexin，PENG Jian，ZHANG Xiaoyu，
    2024(7):39-49.
    [Abstract](137) [HTML](0) [PDF 5.78 M](3862)
    Abstract:
    In this study， a refined in-plane dynamic model of cable-stayed bridges was constructed， and the corresponding free vibration characteristics were analyzed. Firstly， the in-plane motion equations of the cable-stayed bridge were derived using the Hamilton variational principle， and the characteristic frequency equation of the linearized model was determined based on boundary conditions. A three-span cable-stayed bridge with double towers was chosen for the numerical calculation， and the correctness of the corresponding solution was verified through the finite element method. Then， the modal characteristics of the cable-stayed bridge were quantitatively reflected by introducing localization factors. Finally， the effects of structural parameters， cable-deck interaction， and structural systems on the natural frequencies and modes were discussed. The results show that the natural modes of the system exhibit the local characteristics when the natural frequencies of the cable-stayed bridge are close to the ones of pure cable. Moreover， the cable-deck interaction may significantly affect the low-order non-local modes. However， the effects on the higher-order frequencies can be ignored.
    16  Analysis of Influencing Factors on Uncertainty in Modal Testing and its Application on Sensor Layout Scheme
    WANG Zhiyu，CHEN Huazhao，SHI Yuanfeng，?，ZHANG Jingzhao，DAI Kaoshan，
    2024(7):62-71.
    [Abstract](123) [HTML](0) [PDF 3.71 M](3853)
    Abstract:
    The accuracy of modal test results is affected by uncertain influencing factors such as data acquisition， data processing， and parameter estimation. To study the uncertainty levels of modal parameters and their behaviors under different influencing factors in modal testing， a fast uncertainty quantification analysis method based on the state space model and Fisher information matrix （FIM） is adopted. The influence of multiple factors including data duration， sampling frequency， signal-to-noise ratio， and damping ratio of vibration signal on the uncertainty levels of modal parameters is discussed， and a practical way for optimizing the sensor layout scheme through uncertainty analysis is proposed. Results show that the uncertainty level of modal parameters decreases with the increase of data duration， sampling frequency， signal-to-noise ratio， and the number of sensors， and increases with the increase of damping ratio； for uniformly distributed structures， the majority of the sensors at the upper and middle region of the structure and only a few at the lower region is a preferred sensor layout scheme with small overall uncertainty of modal parameters.
    17  Study on Vortex-Induced Vibration and Aerodynamic Force Characteristic of Stay Cables with Ribs Installed
    LIU Qingkuan，，?，HAN Peng，SUN Yifei，，，CHU Zekai，WANG Binxuan，LI Kaiwen
    2024(7):95-110.
    [Abstract](118) [HTML](0) [PDF 24.17 M](3851)
    Abstract:
    Hence， further investigation is needed. Taking the stay cables with ribs installed as the object， a series of wind tunnel tests were conducted to systematically study the effects of the installation methods （through-length installation and intermittent staggered installation）， sizes and numbers of ribs on the VIV， and aerodynamic force. Additionally， the suppression mechanism of vortex-induced vibration （VIV） was analyzed. Results show that stay cables with ribs can effectively suppress VIV compared with standard stay cables. The intermittent staggered installation exhibits a better vibration suppression effect than the through-length installation. The control effect was better for 8 ribs than for 6 and 12 ribs. Increasing rib width and thickness can reduce the amplitude of VIV. The fluctuating lift coefficients of the stay cables with ribs are remarkably smaller than those of the standard stay cables. Moreover， the amplitudes of the power spectrum peaks are significantly reduced， or the peaks are even vanished. This suggests that intermittent staggered rib can weaken the strength of Karman vortex shedding or even control it completely. For aerodynamic forces， the Reynolds number effect on the mean aerodynamic coefficient is significantly weakened by the ribs. Compared to standard stay cables， the installation of ribs throughout the entire length increases the mean drag coefficient of the stay cables. When the installation is intermitte staggered， the increase and decrease in the drag varies with the number and size of ribs and the wind attack angle. When the ribs with the size of 20mm×15mm and the number of 8 are intermittently staggered， good vibration suppression effects can be obtained at all wind attack angles. The maximum reduction of VIV amplitude can reach 96.79%， the mean drag coefficient is near 1.13， and the mean lift coefficient is near 0.
    18  Design of Double-Circular-Arc and Common Tangent Tooth Profile of Harmonic Drive
    WANG Jia-xu ,  ZHOU Xiang-xiang ,  LI Jun-yang ,  XIAO Ke ,  LI Qi
    2016, 43(2):56-63.
    [Abstract](1909) [HTML](0) [PDF 2.08 M](3630)
    Abstract:
    The tooth profile has significant effect on the engagement performance of harmonic drive (HD).In order to improve the engagement quality of HD, double-circular-arc and common tangent tooth profile (DCTP) as the tooth profile of flexspline (FS) were used, the conjugate existent domain (CED) and the conjugate tooth profile were established in Modified Kinematic Method, and the Least-squares fitting approach was adopted to fit it.The backlash, contact ratio, assembly state and relative movement trail were calculated to analyze the meshing performance of HD with a double-circular-arc and common tangent tooth profile.The results have shown that the tooth profile of the FS and the circular spline (CS) used with the DCTP remain continuous engagement, and the engagement point is changed continuously.Moreover, the double-engagement phenomenon is found, the theory conjugate arc length is 109.3mm, and the contact ratio reaches 69.03; compared with the harmonic drive with traditional involute tooth profile, the high engagement performance of harmonic drive can be obtained with the double-circular-arc and common tangent tooth profile.What's more, preferably selecting the coefficient of radial displacement is an important way to eliminate the interference of HD.
    19  PRNet： Progressive Reduction Network for Polyp Segmentation in Uncertain Areas
    HE Dongzhi?，XIAO Xingmei，LI Yunyu，XUE Yongle，LI Yunqi
    2024(6):40-51.
    [Abstract](135) [HTML](0) [PDF 21.14 M](3286)
    Abstract:
    Automatic segmentation of polyp images usually results in low segmentation accuracy due to the various sizes of lesion regions and blurry boundaries. Based on these two perspectives， a novel Progressive Reduction Network （PRNet） is proposed， which first locates polyps and then gradually refines their boundaries. The network utilizes Res2Net to extract features from the lesion region and leverages the multi-scale cross-level fusion module to improve localization accuracy. By combining the attention fusion mechanism with cross-level features in this module， the network can effectively solve the issue of multi-scale lesion areas. Furthermore， PRNet combines an uncertain region processing module and a multi-scale context-aware module when restoring image resolution from top to bottom. The former gradually mines polyp edge information by setting decreasing thresholds to enhance the recognition of edge detail features， while the latter， to improve the overall representation capability of the model， further explores the inherent potential contextual semantics of lesion regions. In addition， a simple feature filtering module is designed in this algorithm to filter the valid information in the encoder features. Experimental results on the Kvasir-SEG， CVC-Clinic， and ETIS datasets show that the Dice coefficients of the algorithm reach 92.09%， 93.05%， and 74.19%， respectively. Compared with other existing polyp segmentation algorithms， PRNet outperforms them and demonstrates its superior robustness and generalization.
    20  Assessment of Fatigue Life for Anchor Plates Based on Fracture Mechanics
    LI Li-feng ,  TANG Wu ,  TANG Jin-liang
    2016, 43(9):82-87.
    [Abstract](761) [HTML](0) [PDF 1.64 M](3054)
    Abstract:
    To investigate the fatigue performance of anchor plates, a composite beam cable-stayed bridge was taken for example in this study. A loading model in the new standard for steel bridge and the rain-flow method were applied to gain fatigue load spectrum, combined with a three dimensional finite element model to identify the typical structural details and fatigue stress spectrum of anchor plates. Initial surface cracks were imported in the typical details, and stress intensity factors of crack tips were calculated. The stress intensity factor and crack size were regressed by substituting in Paris formula, which were integrated to gain the fatigue life of typical structural details. The assessment of fatigue life for anchor plates based on fracture mechanics was then established. The results show that the fatigue life for anchor plate based on fracture mechanics is over 100 years, satisfying the requirement of design and utilization; the crack is developed very slowly in the early time, but when it reaches 10 millimeters, 50% to 80 % of its fatigue life is consumed. Therefore, reinforcement should be timely applied to the anchor plates.

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