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    • 1  Self-supervised Monocular Depth Estimation Based on Semantic Assistance and Depth Temporal Consistency Constraints
    LING Chuanwu，CHEN Hua，XU Dayong，ZHANG Xiaogang?
    2024(8):1-12.
    [Abstract](283) [HTML](3) [PDF 37.67 M](6381)
    Abstract:
    Self-supervised monocular depth estimation methods trained on sequences of monocular images have received considerable attention in recent years by using the photometric consistency loss between adjacent frames instead of depth labels as the supervisory signal for network training. The photometric consistency constraint follows the static world assumption， but the moving objects in the monocular image sequence violate this assumption， which affects the camera pose estimation accuracy and the calculation accuracy of the photometric loss function during the self-supervised training process. By detecting and removing the moving target area， the camera pose decoupled from the target motion can be obtained， and the in?uence of the moving target area on the calculation accuracy of the photometric loss can be discarded. To this end， this paper proposes a self-supervised monocular depth estimation network based on semantic assistance and depth temporal consistency constraints. First， an offline instance segmentation network is used to detect dynamic category objects that may violate the static world assumption， and the corresponding region input pose network is removed to obtain a camera pose decoupled from object motion. Secondly， based on semantic consistency and photometric consistency constraints， the motion status of dynamic category targets is detected so that the photometric loss in the moving area does not affect the iterative update of network parameters.Finally， depth temporal consistency constraints are imposed in non-motion areas， and the estimated depth value of the current frame is explicitly aligned with the projected depth value of adjacent frames to further refine the depth prediction results. Experiments on the KITTI， DDAD and KITTI Odometry datasets verify that the proposed method has better performance than previous self-supervised monocular depth estimation methods.
    2  Multi-scale Fusion Edge Detection Model with Spatial Co-location Rule Based on Dense Extreme Inception Network
    DANG Jianwu，ZHANG Tianyin，TIAN Bin?
    2024(8):13-22.
    [Abstract](217) [HTML](6) [PDF 12.96 M](6329)
    Abstract:
    Edge detection is the basis of many computer vision tasks. Current techniques mainly rely on deep learning， but most models improve the accuracy of predicted edges using Non-Maximum Suppression in the evaluation stage. These models only focus on the accuracy of predicted edges without considering the coarseness and fineness of the edges. To address this issue， this paper proposes a new feature fusion strategy based on the dense extreme inception network. This strategy incorporates top-down multi-scale fusion edge detection with spatial co-location rule and retains the multi-network structure based on the traditional deep learning edge detection side output. The proposed strategy can better integrate the high semantic characteristic of high-layer information with the high-resolution texture characteristic of low-layer information， thereby suppressing pixel confusions in backgrounds and lines that are predicted incorrectly in edge detection. In the feature connection， Concat block is used to replace the single operation of Concat， to better fuse semantic information in different scales. Lastly， a simple attention fusion block is used to fuse outputs of multiple networks. Also， different output prediction maps at different scales are deeply supervised combining the tracing loss. This model is independent of Non-Maximum Suppression. By fully utilizing the multi-scale and multi-level information of the target image， this model improves the accuracy of prediction along with improving images’ edges. The experimental results show that without the morphological Non-Maximum Suppression， on the BIPED data set， the proposed model on ODS， OIS， and AP are 0.891， 0.895， 0.900， respectively； with the morphological Non-Maximum Suppression， the proposed model on ODS， OIS， and AP are 0.894、0.899、0.931， respectively， which is superior to all comparison algorithms involved in this article. Also， on the MDBD data set， optimal results were also achieved.
    3  QEMU-based Framework for SIMD Instruction Replacement Floating-point Instructions
    LIU Dengfeng，LI Dongya，CHAI Zhilei，ZHOU Haojie?，DING Haifeng
    2024(8):70-77.
    [Abstract](152) [HTML](1) [PDF 3.55 M](6324)
    Abstract:
    Now，almost every processor architecture has added support for SIMD （single instruction multiple data） instructions. SIMD instructions can perform the same operation on a set of data simultaneously， enhancing the processing performance of the processor through data parallelism. However， most dynamic binary translators ignore the use of native SIMD instructions and instead simulate floating-point computations in software languages. This paper proposes a framework called FP-QEMU， based on QEMU translation system. FP-QEMU adopts SIMD instructions to optimize and replace floating-point calculation instructions， and completes a complete floating-point implementation on X86 and ARM benchmark platforms. The framework can identify the optimization opportunities of floating-point computation acceleration in dynamic binary translation system and use SIMD instructions to achieve the effect of improving the translation performance of dynamic binary translation system. Using SPEC 2006 as the benchmark， experiments show that compared with QEMU， FP-QEMU cross-platform ARM applications running on X86 computers can achieve a maximum speedup of 51.5% and an average speedup of 37.42%.
    4  Method Based on Parallel CNN-BiLSTM Regression and Residual Compensation for Correcting UAV Navigation Error in GNSS Denied Environment
    HAN Bin，SHAO Yihan，LUO Ying?，TIAN Jie，ZENG Min，JIANG Hong
    2024(8):57-69.
    [Abstract](154) [HTML](2) [PDF 11.77 M](6318)
    Abstract:
    When the global navigation satellite system （GNSS） signal is unavailable， the performance of GNSS/inertial navigation system （INS） integrated navigation system significantly degrades， which leads to the rapid divergence of INS errors of UAV swarms. At present， the neural network model is used to predict the position and speed instead of GNSS navigation information to correct the positioning error of the INS. However， this method suffers from high positioning errors and a sharp decline in prediction accuracy when the trajectory changes suddenly. Therefore， a position and velocity prediction method based on convolution neural networks （CNN） -bidirectional long short-term memory network （BiLSTM） joint residual compensation model is proposed to compensate for inertial navigation errors and improve position and velocity positioning accuracy. Firstly， aiming at the problem of high positioning error of GNSS/INS integrated navigation system after GNSS denial， a time series prediction network is formed by fusing CNN and BiLSTM to train and establish the relationship between inertial measurement unit （IMU） dynamics measurement and GNSS information， so as to realize position and speed prediction. Secondly， aiming at the problem that the prediction effect drops sharply when the trajectory changes abruptly，CNN-BiLSTM is used again to mine the relationship between the IMU dynamics measurement， prediction value and prediction residual， and to predict and compensate the prediction residual. Simulation results show that the proposed model outperforms traditional CNN-LSTM and LSTM network models in terms of prediction accuracy， effectiveness， and stability.
    5  Design and Implementation of a Low Power Personal Location Beacon for Maritime Search and Rescue
    LIAO Mi，NIE Guigen，?，ZHAO Jing，HE Xi
    2024(8):47-56.
    [Abstract](162) [HTML](4) [PDF 42.13 M](6315)
    Abstract:
    This paper designs and implements an improved personal location beacon （PLB） for maritime search and rescue. The PLB has the functions of Beidou navigation and positioning， Beidou short message communication， human vital signs monitoring and reporting， and water touch trigger. What’s more， the proposed PLB supports the COSPAS-SARSAT system. To extend the working time of the PLB， this paper introduces a dynamic power management method to conduct the power channels of different functional circuits. Meanwhile， this paper designs an ultra-low power consumption standby circuit and low power consumption software control scheme to reduce power dissipation. Finally， the prototype of the PLB is tested， respectively， in the adjacent sea areas of Weihai City in Shandong Province and Ningbo to Zhoushan City in Zhejiang Province. The test results of the prototype show that in the standby state， the current of the PLB is 2.3 A， with a standby time exceeding 5 years； in the state of receiving the Beidou short message， the current is 79 mA； and in the state of transmitting rescue messages， the 7 000 mAh 7.4 V battery can send 200 distress messages. Compared to existing products， the proposed PLB in this paper for maritime rescue has lower standby power consumption.
    6  Multi-scale Compressed Sensing Image Reconstruction Based on Filter Pruning
    LIU Yuhong，JIANG Qi?，TAN Lijuan，YANG Heng
    2024(8):34-46.
    [Abstract](185) [HTML](1) [PDF 37.53 M](6313)
    Abstract:
    To address the issue of texture detail blurring in single-scale sampled compressed sensing image reconstruction at low sampling rates and achieve a lightweight reconstruction network， this paper proposes a filter pruning based multi-scale compressed sensing image reconstruction network. In the sampling phase， the image is linearly decomposed by convolution， and then fused with the input image and different scale decomposition features to obtain the compressed sensing measurements. In the reconstruction phase， a coordinate attention based multi-scale dilated residual module is designed， which incorporates positional information into channel attention to enhance the feature learning ability of the network. Moreover， by calculating the entropy of the feature map to judge the importance of the filters， the less important filters is pruned to achieve the purpose of compressing the model. Training and testing are carried out on datasets such as DIV2K， Set5， BSDS68 and Urban100. The experimental results show that the algorithm proposed improves the Peak Signal-to-Noise Ratio （PSNR）， Structural Similarity（SSIM）， and image visual effects. For instance， with a sampling rate of 4% and a test set of Set14， the proposed algorithm improves the PSNR of the reconstructed image by 4.17 dB and 2.39 dB， respectively， compared with CSNet+ and FSOINet， resulting in clearer texture details. Under the premise of slightly reducing the reconstruction effect， a lighter model was obtained， which improved the reconstruction speed.
    7  Value Evaluation Method of Fuel Cell Test Bench for Personalized Customization
    ZHONG Pin?，YAN Haopeng，YUAN Xiaofang，TAN Weihua
    2024(8):91-100.
    [Abstract](132) [HTML](2) [PDF 3.18 M](6304)
    Abstract:
    To address the difficulty in evaluating and quantifying the value of personalized customized fuel cell test bench （FCTB）， a method is proposed to establish a comprehensive evaluation index system of FCTB， based on the principle of FCTB technology and the actual production process. The fuzzy hierarchical analysis method is used to assign weights to the indexes， taking into account the user’s personalized customization needs. This creates a quantitative value evaluation model， which converts the weighting problem into a constrained optimization problem. An improved harmonic search algorithm is then proposed to solve this problem. By designing a solution vector generation mechanism and a parameter adaptive adjustment strategy， the algorithm improves the solution efficiency and search capability of the traditional harmonic search algorithm. Simulation results show that the proposed method has obvious advantages in terms of computational efficiency and accuracy. It is able to achieve quantitative value assessment of different FCTB scenarios according to the user’s personalized needs.
    8  Fuzzy C-mean Multi-spectral Remote Sensing Image Segmentation with Combined Subspace and KL Information
    WU Jiaxin，WANG Xiaopeng?，LIU Yangyang
    2024(8):23-33.
    [Abstract](177) [HTML](3) [PDF 68.76 M](6300)
    Abstract:
    For the problem of insufficient accuracy of traditional fuzzy C-means clustering （FCM） algorithm for noise-containing multi-spectral remote sensing image segmentation， an FCM multi-spectral remote sensing image segmentation algorithm combining adaptive local fuzzy subspace and enhanced KL is proposed. Firstly， the local fuzzy factor is used to automatically eliminate the noise interference and extract the local spatial information of the image by similarity metric and adaptive constraint parameters without relying on parameters. Secondly， the original image information and the local spatial information processed by the fuzzy factor are unified and integrated into the fuzzy subspace clustering， and the multiple channels of the image are adaptively weighted to enhance the segmentation accuracy. Finally， the KL information is introduced into the FCM objective function in the form of regular terms for clustering calculation， and the outliers in the membership matrix are removed by ESD （Extreme Studentized Deviate） detection model to enhance the KL prior information and reduce the ambiguity of the membership. The experiments of real multi-spectral remote sensing image segmentation show that in the simulation of noise environments， the algorithm in this paper can suppress the noise and can guarantee the segmentation accuracy better at the same time. In addition， the algorithm in this paper outperforms several other variant FCM algorithms in terms of evaluation indexes such as segmentation accuracy， fuzzy coefficient， and peak signal-to-noise ratio.
    9  Design of C-Band RLC Negative Feedback Power Amplifier Based on GaAs HBT
    FU Haipeng?，YAO Panhui
    2024(8):101-108.
    [Abstract](122) [HTML](1) [PDF 19.63 M](6299)
    Abstract:
    A linear negative feedback power amplifier （PA） based on gallium arsenide （GaAs） heterojunction bipolar transistor （HBT） in the C-band is proposed. The design employs a three-stage common emitter （CE） structure and utilizes two different active linear biases to enhance the linearity of the PA. Simultaneously， an RLC negative feedback network is incorporated to improve stability and broaden the operational bandwidth. Addressing the issue of gain reduction in traditional feedback network structures， the RLC negative feedback network can effectively mitigate the impact of gain reduction induced by feedback by adjusting the inductance values within the feedback network. Test results demonstrate that， at room temperature， within the frequency range of 5.1 GHz to 7.4 GHz， a gain exceeding 28 dB is achieved. In the linear operating frequency range of 5.9 GHz to 7.1 GHz， the average gain is 29.5 dB， and both S11 and S22 are less than -10 dB. Complying with the wireless LAN standard 802.11a， a 20 MHz 64-QAM signal is utilized and the output power achieving an EVM of -30 dB ranges from 18.9 dBm to 22.5 dBm. Between 5.9 GHz and 6.2 GHz， the saturated output power exceeds 30 dBm， and the maximum power added efficiency （PAE） is greater than 35%.
    10  Integral Back-stepping Linear Active Disturbance Rejection Control for Automatic Operation of Urban Rail Trains
    YUE Lili，WANG Yidong，XIAO Baodi，?，WU Xiaochun
    2024(8):78-90.
    [Abstract](134) [HTML](2) [PDF 5.39 M](6298)
    Abstract:
    Aiming at the speed control problem of the train under external disturbance and uncertain dynamics， a composite control scheme combining integral back-stepping （IBS） method and linear active disturbance rejection control （LADRC） is designed. Firstly， considering the strong coupling of the train， a multi-particle model with time-varying coefficients is established to better conform to the real longitudinal dynamic characteristics and force conditions of the train. Secondly， to reduce the difficulty of parameter adjustment， the tracking differentiator （TD） and the extended state observer （ESO） are in linear form. TD is used to obtain the differential signal and has a filtering effect. The problem of differential explosion in back-stepping method can be solved by using the TD to derive the virtual control quantity. ESO is used to estimate the total disturbance in real-time. In addition， the IBS method is used to improve the error feedback control law， and an integral back-stepping linear active disturbance rejection control （IBS-LADRC） algorithm is designed. Finally， the convergence of the observation error and the stability of the closed-loop system are proved. Combined with the parameters of AH electric multiple units of Hangzhou Metro Line 6 and the actual line data， the simulation comparison is carried out， and the IBS-LADRC is compared with the back-stepping method， LADRC algorithm and PID control.The results show that under the IBS-LADRC method， the velocity error of each power unit is within ±0.04 km/h， the acceleration is within ±1 m/s2， and the acceleration and velocity error change smoothly. The coupler force is the smallest and the change is the most gentle compared with the other three methods， and the maximum coupler force is only 2 320 N. The proposed control strategy has high tracking accuracy for the expected speed of the train， which is conducive to ensuring the safety of the coupler， preventing the coupler from breaking， and improving the safety， stability and passenger comfort of the train operation.
    11  Design of a CL-LDO with Wide Range Load
    TANG Junlong?，GUAN Hao，DENG Huan，LI Zhentao，ZOU Wanghui
    2024(8):109-116.
    [Abstract](126) [HTML](2) [PDF 12.90 M](6293)
    Abstract:
    Aiming at the development trend of integrated circuits （ICs） with rapid increase in scale and power consumption， a novel capacitor-less low-drop-out linear voltage regulator （CL-LDO） has been designed to provide a wide range of load currents. To solve the issues of stability and transient response caused by the requirements of a wide range of load currents and no off-chip capacitor， a dynamic zero-point compensation method and a transient enhancement circuit structure are proposed， which not only ensures the stability of the whole circuit in the full load range， but also achieves excellent transient characteristics. Based on 0.11 μm CMOS technology， the circuit design， layout design and simulation are completed. The simulation results show that the overall loop gain can reach 68 dB with a minimum phase margin of 56° within the load range of 0 mA to 500 mA， the output overshoot and undershoot are 56 mVand 141 mV， and their settling time is 2 μs and 0.78 μs， respectively， when load current transients range from 1 mA to 500 mA （Δt=500 ns）， the power supply rejection （PSR） is -67.2 dB@1 kHz， and the load regulation rate is 0.137 μV/mA.
    12  Progressive Mural Inpainting Algorithm Based on Joint Kernel Prediction and Feature Reasoning
    CHEN Yong，?，ZHAO Mengxue，DU Wanjun，TAO Meifeng
    2024(6):1-9.
    [Abstract](225) [HTML](2) [PDF 103.06 M](6048)
    Abstract:
    Aiming at the existing depth model that fails to take into account both pixel-level features and semantic-level features at the same time when repairing nurals， resulting in problems such as lack of texture fineness and structural distortion， a progressive mural inpaining algorithm that combines kernel prediction and feature reasoning is proposed. Firstly， the regional progressive module is designed to realize the progressive mapping of mural features through partial convolution. Then， a dual-branch repair module is proposed， in which the kernel predicts the volume integral branch to realize the pixel-level repair of the damaged area. The semantic feature reasoning branch introduces gated deformable convolution and combines the semantic consistency attention mechanism to realize feature reasoning to complete the semantic-level repair of damaged murals. Finally， the two-branch repair results are fused into the output to minimize the reconstruction error and improve the repair accuracy. Through the digital restoration experiment of Dunhuang murals， the results show that the restored murals by the proposed method have better structural texture characteristics， which are better than the comparison algorithm in terms of evaluation indicators.
    13  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](2583) [HTML](0) [PDF 762.94 K](5660)
    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.
    14  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](911) [HTML](0) [PDF 2.41 M](4853)
    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.
    15  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](1241) [HTML](0) [PDF 5.83 M](4851)
    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.
    16  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](1203) [HTML](0) [PDF 3.25 M](4719)
    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.
    17  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](2352) [HTML](0) [PDF 1.90 M](4703)
    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.
    18  Algorithm of Medical Image Reversible Data Hiding for Contrast Enhancement
    OU Bo，JIANG Xiyuan，XIONG Jianqin
    2022, 49(4):26-34.
    [Abstract](898) [HTML](0) [PDF 5.89 M](4334)
    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.
    19  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](174) [HTML](2) [PDF 3.71 M](4215)
    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.
    20  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](167) [HTML](1) [PDF 5.78 M](4149)
    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.

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