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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](2380) [HTML](0) [PDF 762.94 K](5395)
    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](792) [HTML](0) [PDF 2.41 M](4583)
    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](1013) [HTML](0) [PDF 5.83 M](4555)
    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](1018) [HTML](0) [PDF 3.25 M](4495)
    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](2179) [HTML](0) [PDF 1.90 M](4183)
    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](705) [HTML](0) [PDF 5.89 M](3891)
    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  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](1708) [HTML](0) [PDF 2.08 M](3311)
    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.
    8  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](697) [HTML](0) [PDF 1.64 M](2880)
    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.
    9  Study on Work Hardening Mechanism of Hadfield Steel during Deformation Process
    ZHANG Fu-quan HE Cui ZHOU Dian-wu
    2016, 43(12):11-16.
    [Abstract](1431) [HTML](0) [PDF 1.53 M](2550)
    Compression test of ZGMn13Cr2 Hadfield steel was carried out by Gleeble-3500 thermal simulator at the deformation temperature of 298 K under a constant loading strain rate of 0.1 s-1 and with the compressive deformation of 5%, 30%, and 50%, respectively. The effects of compressive deformations on the microstructure evolution and work hardening mechanism of ZGMn13Cr2 Hadfield steel were analyzed by optical microscope, vickers micro-hardness machine, transmission electron microscopy and X-ray diffraction. The test results show that a large number of deformation bands appeared in the grains of compressed high manganese steels. The deformation bands intersected, tangled and isolated with each other. A great deal of high density dislocation was entangled into dislocation cells or dislocation walls with the compression amount of 5%. Deformation twins appeared in the matrix when the compression amount was 30%. With the increasing of compressive deformation, the amount and volume fraction of the twins increased gradually. When the compression amount was 50%, the micro-hardness of water-quenched high manganese steel increased by 125% compared with the initial state, showing HV560.8. Meanwhile, XRD results show that the matrix structure remained austenite and with a bit of carbide, but no deformation-induced martensites were founded in these deformed samples. With the increasing of compressive deformation, work hardening mechanisms of Hadfield steel changed from dislocation strengthening into mainly relying on deformation twin supplemented by dislocation and stacking fault mechanisms.
    10  Prokaryotic Expression, Purification, and Protein-interaction Analysis of Human FOXA1 Protein
    TAN Yong-jun,CHEN Zhu-lin,CHEN Tuan-hui,XIANG Qin
    2016, 43(6):104-108.
    [Abstract](1379) [HTML](0) [PDF 1.40 M](2542)
    To identify proteins interacting with transcription factor FOXA1,different prokaryotic expression vectors for human FOXA1 protein were constructed and the proteins of FOXA1 C-terminus and FOXA1 N-terminus were purified. They provided a material foundation for future studies of FOXA1-interacted proteins. Total RNAs were extracted from human breast cancer MCF7 cells and reverse transcribed into cDNAs. The full length cDNA of FOXA1 was amplified by PCR, and the C-terminal and N terminal segments were also amplified respectively. The different FOXA1 cDNA fragments were cloned into a prokaryotic expression vector pGEX-4T-1. The correct vectors were confirmed by double restriction enzyme digestion and DNA sequencing and transformed into E. coli BL21 Rosetta DE3. The FOXA1 proteins were purified with Glutathione Sepharose 4B and analyzed through SDS-PAGE electrophoresis and Western blot. GST Pull-down experiments were performed with lysates of MCF7 cells and FOXA1 proteins to test the interaction between FOXA1 and a known FOXA1-interacted protein TLE3.Prokaryotic expression vectors of pGEX-4T-1-FOXA1-C and pGEX-4T-1-FOXA1-N were constructed successfully. The proteins of FOXA1 C-terminus (GST-FOXA1-C) and FOXA1 N-terminus (GST-FOXA1-N) were purified by Glutathione Sepharose 4B. It was confirmed that the purified GST-FOXA1-C was able to interact with the known FOXA1-interacted protein TLE3 in the Pull-down experiment.
    11  Lightweight Human Pose Estimation Network Based on HRNet
    LIANG Qiaokang?,WU Yue
    [Abstract](436) [HTML](0) [PDF 16.29 M](2139)
    The current human pose estimation networks are difficult to be widely used in mobile devices and embedded platforms due to the arithmetic power and memory limitations. To address this problem, this paper proposes a lightweight human pose estimation network X-HRNet with HRNet as the basic framework and uses the ResNeXt module to replace the common basic module to reduce the parameters and computational complexity of the network. The proposed model achieves 78.2% accuracy on the COCO validation set, which is 1.9% higher than that of the HRNet, the number of parameters decreases by 22.2M, and the computational effort decreases by 27.3 GFLOPs. The proposed X-HRNet is a method with the combination accuracy and lightweight, which proposes a new lightweight human pose estimation network for embedded platforms by reducing the computation and the number of parameters effectively while maintaining accuracy.
    12  Experimental Study on Shear Performances of Structural Adhesives at Different Temperatures
    HU Ke-xu DONG Kun YANG Yao-wu
    2016, 43(7):120-125.
    [Abstract](1602) [HTML](0) [PDF 1.46 M](2128)
    The structural performances including shear-strength, stiffness, and failure mode of structural adhesives with two different curing schedules at room and high temperatures were investigated. The test results showed that the high temperature curing on the structural adhesive after room temperature curing can improve the value of glass transition temperature Tg by about 30 ℃. Moreover, the shear performances of the structural adhesives were deteriorated with the increase of the temperature, and the maximum degradation rate occurred within the temperature range of Tg±20 ℃. It is indicated that the glass transition temperature Tg was critical to the shear behavior of the structural adhesive at the high temperature. In a whole, the high temperature curing can improve the value of glass transition temperature, and it is helpful to delay the degradation of shear performance at the elevated temperature. Based on the test results, the normalized relationship between the shear performances and temperature were eventually proposed, in which glass transition temperature was considered.
    13  Scheduling Algorithm in Distributed Systems Based on Non-Cooperative Game
    TONG Zhao XIAO Zheng LI Ken-li LIU Hong LI Jun
    2016, 43(10):148-154.
    [Abstract](1439) [HTML](0) [PDF 1.31 M](2072)
    To address the task scheduling problem in distributed systems, based on an important feature of task scheduling in distributed computing environment, we have established a non-cooperative game framework for multi-layer multi-role, and put forward a distributed reinforcement learning algorithm of the joint scheduling strategy of Nash equilibrium. Compared with static scheduling algorithm, the proposed algorithm needs less system information. It enables the scheduler to actively learn task arrival, perform related knowledge and adapt to the adjacent scheduler allocation policy. The target is to move the schedulers strategy toward Nash equilibrium. Simulation experiments show that the proposed algorithm achieves excellent performance in expected response time of tasks and fairness, compared with classical scheduling algorithms such as OLB, MET and MCT.
    14  Dynamic simulation on the pressure fluctuation of the Hoffmann hydraulic system
    liu xi ling
    [Abstract](1988) [HTML](0) [PDF 0.00 Byte](1937)
    Based on energy conservation law, combine with system dynamics, hydromechanics, the mathematical model of the Hoffmann Hydraulic Mechanism (HHM) was established using chamber method. Then, the Ronge-Kutta method was selected to solve the state equations. At last, with the SIMULINK in MATLAB, the system’s dynamic characteristics was analyzed, and the oil pressure changed with time was investigated, both are of direction significance for the system characteristic study and design improving.
    15  Design Research on Battery Heating and Preservation System Based on Liquid Cooling Mode
    LI Gang HUANG Xiangdong FU Xingfeng YANG Yong
    2017, 44(2):26-33.
    [Abstract](1903) [HTML](0) [PDF 2.66 M](1931)
    In order to solve the battery charge problem under low temperature, liquid cooling battery system was analyzed and studied, and thermal management with heating and preservation was designed. According to the battery low temperature test data and the requirement of battery heating and preservation, battery heating calculation model was proposed on the basis of the theory formula. The performance of battery heating system was studied by the proposed model. Optimization design of the liquid cooling control system was also investigated according to the analysis results. The results show that the liquid cooling battery management system exhibits excellent performance of low temperature heating and preservation.
    16  Multi-objective optimization of intake and exhaust system of a gasoline engine using nondominate sorting genetic algorithm-II
    Huang Ming
    [Abstract](2037) [HTML](0) [PDF 0.00 Byte](1856)
    An improved nondominate sorting genetic algorithm-II (NSGA-II) is used to optimize the intake and exhaust system of a single cylinder gasoline engine, whose torque at middle range speed was decreased a lot after a catalyst added. First a full GT-power model was set up and verified based on experiment data. Then the intake and exhaust system was selected as the optimization variables, the effects of the diameters and lengths of intake/exhause pipe on the engine performance were investigated individually. Finally an improved nondominate sorting genetic algorithm-II (NSGA-II) is used to solve the multi-objective optimization problem. The results show that the diameters and lengths of intake/exhause pipe have different range and degree of influence on the engine torque. It is different to satisfy the multi-objectives optimization simultaneity by adjusting those variables separately. The improved NSGA-II, with an elitist preserve strategy and duplicates removing algorithm added, can get the Pareto solution set effectively and satisfy the multi-objective optimization.
    17  Analysis and Robust Design of Geometric Accuracy of a Three-axis CNC Surface Grinding Machine
    LIU Jiang-nan HONG Yi-hai
    2016, 43(4):1-8.
    [Abstract](1944) [HTML](0) [PDF 1.26 M](1796)
    In order to distribute the geometric errors of parts economically and reasonably, a method for the analysis and design of geometric accuracy was proposed. According to the specific structure of a three-axis CNC surface grinding machine, a geometric error propagation model including 21 parameters was established on the basis of multi-body system theory and homogeneous coordinate transformation method. The model was verified and it had ideal prediction accuracy. Key geometric errors were analyzed by using orthogonal design and parameter test of DOE methods. After cost analysis and error tracing, a cost-quality model for key geometric error variables was established on the basis of robust design theory. At last, the tolerances of key geometric error variables were distributed according to this model. The results have shown that the methods mentioned above are effective in the distribution of the geometric accuracy of grinding machine.
    18  Numerical Analysis of Hysteretic Performance of Double-steel-layer-concrete Composite Shear Wall
    LUO Yong-feng, LI Jian, GUO Xiao-nong
    2014, 41(6):57-62.
    [Abstract](1504) [HTML](0) [PDF 1.76 M](1756)
    This paper summarized the current research status of double-steel-layer-concrete composite shear walls. Then, it presented a brief introduction to the experiments of double-steel-layer-concrete composite shear wall. Based on the experimental study of double-steel-layer- concrete composite shear wall, the hysteretic behavior of the wall was analyzed and the finite element model with initial imperfections was established. Compared with the experimental results, the FEM model was verified to be efficient. Through numerical analysis, the influence of several parameters, including the high aspect ratio, the width-to-thickness ratio and the axial compression ratio, on the hysteretic behavior of the wall was explored. The numerical results have shown that all the 3 parameters have effects on the mechanical performance of the wall, the axial compression ratio is the most important factor for the loading capacity of the wall and the high aspect ratio and width-to-thickness ratio are the most important factors for the initial stiffness of the wall.
    19  Study on Assessment Method for Comprehensive Thermal Performance of Existing Building Envelopes
    YANG Changzhi ,LEI Xiaohui,ZHANG Ling,WANG Lin
    2018, 45(7):150-156.
    [Abstract](856) [HTML](0) [PDF 687.82 K](1698)
    This paper proposed a method for the comprehensive thermal performance assessment (equivalent heat transfer coefficient) of building envelopes in existing buildings. This method is based on the index evaluation and equivalent energy consumption model, which integrates many evaluation indexes into an equivalent index. The thermal performance and energy-saving potentiality of the building envelope are evaluated by calculating and comparing the heat transfer coefficient of the two equivalent energy consumption models. It is shown that only measurement of indoor and outdoor temperature is needed, while measurement of every parameter in the envelope structure is not needed, which can overcome the difficulties in testing the existing buildings with complex structures. The proposed method can assess the total thermal performance of building envelope rapidly and evaluate the necessity of retrofitting before energy-saving renovation.
    20  Development and Injury Parameters Research of a FE Model of Lower Limb with High Precision for Adult Pedestrians
    LAN Feng-chong HUANG Wei CHEN Ji-qing WU Kai
    2016, 43(10):42-51.
    [Abstract](1100) [HTML](0) [PDF 2.63 M](1642)
    In order to study the biomechanical response and injury mechanisms of pedestrian`s lower limb during impact, a three-dimensional FE model of lower limb for adult pedestrians with high precision was developed on the basis of human anatomical structure. The lower limb model included complete anatomical structure of femur, tibia, fibula, patella as well as soft tissues such as skin, fresh, ligaments, capsule meniscus and cartilage. Considering the nonuniformity of the section of cortical bone, a long bone model was developed based on CT data with the thickness and the shape of the cortical bone section varying continuously. In comparison with other modeling methods, cortical bone was modeled with two-layer solid elements to obtain higher precision and efficiency. The injury criterions of pedestrians′ lower limb such as the ultimate bending moment of femur and tibia were obtained by modeling related biomechanical experiments. In addition, the influence of the thickness of cortical bone and the impact direction to injury mechanism and injury parameters of lower limb were analyzed. The injury parameters can provide important reference for the design of cars.
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