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YANG Xi, TIAN Chong, FANG Ruyi, LIU Zeyu, ZHANG Yinhang, LEI Kejun
Available online:May 19, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022353
Abstract:The classical maximum eigenvalue detection (MED) algorithm has excellent performance in detecting correlated signals. However, with the increasing signal dimensionality, the MED algorithm faces serious problems in the calculation efficiency and implementation of test statistic and decision threshold, thus greatly limiting the further application of the algorithm in modern cognitive communication systems. To this end, a low-implementation complexity MED algorithm based on a numerical analysis theoretical framework is proposed. The new algorithm uses the Rayleigh quotient accelerated power method to iteratively compute the test statistic, which has a fast convergence rate in detecting high-dimensional signals compared with the classical power method; meanwhile, different from the classical look-up table method, a threshold calculation method based on the cubic spline interpolation method is proposed, which can quickly determine the decision threshold corresponding to any given target false-alarm probability. The proposed MED algorithm effectively improves the computational efficiency and reduces the complexity of algorithm implementation while maintaining the detection performance of the original algorithm, which is particularly attractive for spectrum sensing problems in high-dimensional conditions. Finally, the simulation results demonstrate the effectiveness of the proposed algorithm.
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Available online:May 19, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022355
Abstract:A terahertz fundamental up-conversion mixer with a high local oscillator (LO)/ radio frequency (RF) and local oscillator / intermediate frequency (IF) port isolation was presented, which was in the IHP 0.13μm SiGe BiCMOS process. The mixer adopted Gilbert’s double-balanced structure, local oscillator signal was transmitted through the Coplanar Waveguide (CPW) to suppress the transmission asymmetry caused by the strong parasitic coupling effect in the transmission process, which reduced the characteristic of LO/RF port isolation deterioration caused by the asymmetry. By adopting an asymmetric switch interconnection structure, the imbalance of the parasitic coupling of the local oscillator signal at the collectors of the switching transistors was reduced, and the cancellation efficiency of the local oscillator signal at the collectors of the switching transistors was improved. And the local oscillator signal was suppressed at the port of intermediate frequency by arranging the position of the transconductance transistors in a reasonable layout. The post-simulation results show that under the power supply voltage of 2.2V, the local oscillator signal is 230GHz and the intermediate frequency signal is 2-12GHz, when the up-conversion mixer works at 218-228GHz, the LO/RF port isolation is greater than 24dB, LO/IF port isolation is greater than 20dB, the conversion gain is -4dB to-3.4dB. The output 1dB compression point is -14.8dBm with an intermediate frequency signal is 10GHz. The DC power consumption is 42.4mW, the core area of the chip is 0.079mm2.
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YUAN Yongjie, YANG Liang, CHEN Shenghai, MA Rongchang
Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022296
Abstract:Free space optical (FSO) communications offer high speed, low cost, and strong anti-interference ability. However, the atmospheric turbulence-induced fading causes deterioration in the performance of FSO communication systems. The conventional solution is to use RF links as parallel communication links to improve the system performance. On the other hand, reconfigurable intelligent surfaces (RIS) can be employed to further improve the received signal-to-noise ratio of the RF link due to its advantages of low loss, easy deployment, and no complex coding and decoding. In this paper, an RIS-assisted hybrid RF-FSO transmission system is proposed to improve the communication quality of service. Based on this hybrid model, exact expressions for the outage probability, average BER, and channel capacity are derived, and Monte-Carlo simulations are presented to verify the accuracy of the analytical results. Results show that the performance of the proposed system is significantly improved compared to the conventional hybrid RF-FSO system.
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Available online:May 17, 2022 DOI:
Abstract:The mechanism for asymmetric transmission is an important issue for enhanced sensing, amplification and asymmetric control of elastic waves. Parity-Time symmetric systems may provide a simple solution. The concept of Parity-Time symmetric systems comes from quantum mechanics, and one of its characteristics is unidirectional reflectionlessness. A PT symmetric beam for flexural waves is designed, which is based on piezoelectric shunting technology. Firstly, the PT symmetric condition is derived. Then, based on the effective medium method and finite element simulation, it is verified that the effective parameters of gain and loss unit meet the PT symmetric condition. The tunability of exception points is studied by changing the resonant frequency and the shunting resistance. Finally, the scattering property of the PT sym-metric beam is derived by transfer matrix method and finite element simulation, and the relationship between exceptional points and unidirectional non-reflection is illustrated. The calculated and simulated results show that the PT symmetric beam has several exceptional points including 511Hz and 520.5Hz. When the incident flexural waves of 511Hz is applied at the right side of the PT symmetric beam, the reflection coefficient is close to zero. However, when the frequency of the incident flexural waves changes to 520.5Hz, it should be applied on the left side of the PT symmetric beam in order to gain a total transmission without reflecting. The structure of the proposed PT symmetric beam is simple and the exceptional points of it are tunable, which can be used to achieve better asymmetric transmission of flexural wave.
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Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022297
Abstract:With the rapid development of Internet, virtual communities are emerging. While providing innovative resources, these communities also have problems such as low willingness of users to share and lack of good incentive mechanism. Blockchain can better solve these problems and promote community knowledge sharing. This paper constructs an online community knowledge sharing scheme based on Multi Chain, puts forward the resource access and storage mode of "metadata cloud storage" and designs the metadata information table in detail, designs the overall framework of the knowledge sharing scheme and the key processes of some businesses, puts forward the consensus mechanism of "Nominated Proof of Stake (NPOS) to design the blockchain network, Some functions of online community knowledge sharing are realized. Through analysis and experiment, the scheme of this paper has good scientific rationality, safety and execution efficiency, and has good reference value for the development of other related projects.
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Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022299
Abstract:Affected by suspended particles such as haze in the atmosphere,images taken outdoors often suffer from low contrast and low visibility. Existing dehazing methods fail to make full use of the local feature information of the image, and cannot fully extract the global details of the image. Therefore, there are problems such as incomplete dehazing and loss of image details. For this reason, this paper proposes a T-shaped image dehazing network based on wavelet transform and attention mechanism. Specifically, the proposed network obtains the edge detail features of the hazy image by performing multiple discrete wavelet decomposition and reconstruction on the image, and proposes a feature attention module that takes into account both the global feature and the local information extraction of the image, which strengthens the network"s learning in image visual perception and detail texture. Secondly, in the process of feature extraction, a T-shaped method is proposed to obtain multi-scale image features, which expands the network"s representation ability. Finally, perform color balance on the reconstructed clear image to obtain the final restored image. A large number of experimental results in synthetic data sets and real data sets show that the network proposed in this paper has superior performance compared with other existing network models.
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Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022300
Abstract:This paper proposes a state-sensitive event-triggered H∞ control strategy to solve the problem of unmanned ground vehicle (UGV) path tracking control under communication restriction. Firstly, the corresponding path tracking control model is established according to the dynamics of the connected vehicle. Secondly, a novel state-sensitive event-triggered communication (SS-ETC) strategy according to the state perception of path tracking in real time is proposed. Then, an event-triggered H∞ controller is designed by combining with time delay system modeling method and Lyapunov stability theory. The proposed dynamic event-triggered communication strategy based on state perception can dynamically adjust the communication threshold according to the state measurements of the control system, and effectively realize the adaptive co-design of UGV communication and control. Finally, the effectiveness of the proposed dynamic event-triggered control strategy is verified by simulation experiments.
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Chen jian, Zhuang yao yu, Yang dan, Zhang jun jie
Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022351
Abstract:Although MIMO technology can improve the utilization rate of spectrum, multi-dimensional signal processing brings great challenges to the detection of MIMO signals. Based on the analysis of various MIMO detection algorithms, QR decomposition is selected as the research object, which is a kind of nonlinear algorithm. In order to obtain higher performance of detection, the sorted QR decomposition is further studied and propose the sorting scheme based on L1-norm. Using Matlab for performance simulation, the L1-norm sorting strategy and the L2-nrom sorting strategy have basically the same impact on MIMO system, but the L1-norm sorting strategy reduces the computational complexity. On this basis, the hardware structure of improved sorted QR decomposition by Givens rotation on FPGA is proposed. Comparing with the solution of L2-norm, the L1-norm strategy reduces at least 29.2% combinational logic resources and 32.4% register resources when calculating a single column norm in the realization of 4×4 channel matrix decomposition. Comparing with similar designs, the frequency of operating clock has been significantly improved.
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wangzhenyu, Guo Yang, Li Shaoqing, Zeng Jianping
Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022352
Abstract:With the development and application of communication networks, the Internet of Things carries the safe transmission and storage of a large amount of sensitive information. Since devices are usually small in size and resource-constrained, complex security primitives are not suitable for authentication of lightweight IoT devices. This paper proposes a lightweight anonymous key shared authentication protocol for IoT devices, which generates a shared key by the physical unclonable function(PUF) and uses security primitives such as the MASK algorithm and the Hash function. The security analysis and verification are accomplished by Ban logic and ProVerif to prove that the protocol ensures security attributes such as anonymity, non-repudiation, and forward/backward confidentiality. Compared with other protocols, this protocol has the characteristics of low computing cost, small communication overhead and storage capacity, and high security performance, which is suitable for the secure communication transmission of resource-constrained devices.
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LIU Guangyu, CAO Yu, ZENG Zhiyong, ZHAO Enming, XING Chuanxi
Available online:May 17, 2022 DOI: 10.16339/j.cnki.hdxbzkb.2022354
Abstract:Sonar image is seriously polluted by noise, which leads to the problem of low precision in underwater multi-target segmentation.Therefore, an underwater multi-object segmentation technique based on self-adjusting spectrum clustering combined with entropy weight method is proposed.The technology first by self-tuning spectral clustering of sonar image pixel clustering processing, make the image is divided into multiple independent area, and then according to the characteristics of complementarity and more sections of the redundancy of the statistical information entropy characteristics, brightness, contrast, long and narrow degree, entropy weight method is used to analyse the characteristics more empowerment and the optimal selection of a target area,Then the optimal target region is matched with all regions by multi-feature similarity. Finally, all target regions are segmented automatically by adaptive threshold iterative method according to the matching results of similarity. Experimental results show that there is not over-segmented of noise interference regions, and target regions segmented have higher accuracy, which verifies the effectiveness of the proposed method.
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XU Chao1，2，WEI Xiaodang1?，MENG Ya1，YANG Yang1，2，JIA Bin3
Abstract:To examine the impacts of freeze-thaw cycles on the performance of geogrid reinforced soil slope and the inhibition effect of reinforcement on sand slope deformation， two model tests were conducted on 1.2 m high slopes subjected to 7 freeze-thaw cycles under -25 ℃ and 30 ℃ conditions. The tests compared the performance of reinforced and unreinforced slopes， analyzing qualitative and quantitative variations in heat transfer， moisture migration， settlement， and lateral deformation of the slopes under freeze-thaw cycles. The results indicated that the slope temperature exhibited periodic changes during freeze-thaw cycles， with diminishing influence of external temperature from the free surface inward. During freezing， moisture migration within the slope occurred bidirectionally toward the free surface and base， while vertical migration predominated during thawing due to gravity. The slope settlement demonstrated periodic frost heave and thaw subsidence， with cumulative total settlement increasing with the number of freeze-thaw cycles. The slope displacement displayed freeze-expansion and thaw-induced contraction， and the total displacement increased with the number of freeze-thaw cycles. Reinforcement hindered vertical moisture migration within the slope， thereby changing the temperature field of the slope， and reinforcement effectively mitigated the deformation of the slope caused by freeze-thaw action.
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WU Wenliang?，LIANG Junxuan，PENG Junlin
Abstract:During the construction of double-layer porous asphalt pavement， a binder layer needs to be laid to ensure that the upper and lower layers are bonded by enough binding force to resist potential pavement diseases during service. To investigate the dosage range and force characteristics of the binder layer of double-layer porous asphalt pavement， this paper utilized the pressure film and pavement texture scanner to obtain the interlayer contact characteristics of both single-layer and double-layer porous asphalt pavement， thereby determining the recommended dosage of the binder layer for the double-layer pavement； and the oblique shear test was conducted to obtain the failure characteristics of the binder layers in both single-layer and double-layer porous asphalt pavement. The results indicate that the interlayer contact area of the double-layer porous asphalt pavement is larger， which is approximately 1.5 times that of the single-layer porous asphalt pavement. The OGFC mix used in the lower layer of the double-layer porous asphalt pavement exhibits more microscopic concave and convex structures and a larger surface area， which is about 1.18~1.20 times that of the AC mix. Based on the surface area multiplier relationship and the standard recommended value， it is recommended that the dosage of the binder layer for double-layer porous asphalt pavement be 0.8~1.2 L/m2. The shear resistance of the binder layer in double-layer porous asphalt pavement is superior to that in single-layer porous asphalt pavement. The interlayer shear strength of single-layer porous asphalt pavement is solely provided by the bonding force of the binder layer. The interlayer shear strength of double-layer porous asphalt pavement is provided by the bonding force of the binder layer and the interlocking of interlayer particles. After reaching the maximum shear force， the interlayer particles continue to resist shear deformation， and the shear resistance does not decline abruptly.
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CHEN Changfu1，2?，TIAN Tao1，2，FU Hongsong1，2，CHEN Binfeng1，2，CHEN Xiaoqi1，2，ZHANG Genbao3
Abstract:Recoverable anchors， characterized by low carbon footprint and environmental friendliness， have been increasingly applied in urban foundation pit support projects. However， the evolution of their bearing performance under cyclic traffic loading has not been thoroughly studied. In this study， element-scale tests were conducted to examine the mechanical characteristics of the anchor-rock interface under different cyclic loading parameters. These tests captured the complete shear stress-shear displacement curve （i.e.， τ-s curve） of the anchor-rock interface under cyclic loading. Based on the experimental results， a unified model was developed to describe the degradation of shear strength at the anchor-rock interface， accounting for the effects of the reference load ratio and the number of load cycles. Based on the morphological characteristics of the τ-s curve at the anchor-rock interface， a composite τ-s curve model for the anchor-rock interface was established， consisting of a linear segment and a sudden drop curve. Furthermore， a unified degradation model for the τ-s curve of the anchor-rock interface was developed， accounting for the effects of the reference load ratio and the number of load cycles. The model demonstrates good predictive performance. Finally， a theoretical framework of load transfer of recoverable anchors under cyclic loading considering the Poisson effect was established， and the influence of cyclic loading on the ultimate bearing capacity of engineering anchors was investigated. The research results can provide a reliable theoretical basis for the engineering application of recyclable anchors.
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Axial mechanical properties of shear key double-layer grouting connection in modular steel structure
BAI Jiulin1，2，YANG Ji1，2，LIANG Tianlong2，3，LIU Yifeng4，JIN Shuangshuang5?，DENG Shibin4
Abstract:Modular steel structures as an efficient， environmentally friendly， and sustainable construction method， and the connection between the units will directly affect the overall stability and seismic performance of the structure. However， the common connection methods in modular steel structures， such as welding， bolted connections， and prestressed connections， exhibit several challenges including low construction efficiency， susceptibility to installation errors， and limited working space. In this paper， a novel shear key double-layer grouting connection is proposed， which has good applicability to corner column joints， side column joints and middle column joints of modular steel structures. In order to evaluate the axial mechanical properties of the novel connection， 8 connection specimens were produced for push-out tests， and the effects of shear key spacing， grout strength， connection length and number of grout layers on the failure forms， tensile capacity and strain distribution of the specimens were investigated. Based on the theoretical analysis， the formula for calculating the tensile capacity of the shear key double-layer grouting connection is derived. The effectiveness and accuracy of the formula are verified by comparing with the test results， which can provide a theoretical basis for the engineering application of the novel connection in the modular steel structure.
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Abstract:The rapid urbanization has led to a tightening of land resources， often resulting in structures with small spacing between adjacent buildings. Under dynamic loads such as earthquakes， this may cause excessive relative displacement between adjacent structures， potentially leading to collision-induced damage. This paper proposes an energy-dissipation enhanced torsional eddy current damper （EDE-TECD） for vibration reduction in adjacent structures. The basic structure and operational mechanism of the EDE-TECD are first explained. Based on a rack-and-pinion speed amplifying device， a damping coefficient estimation formula for the EDE-TECD is derived. A simplified motion equation for two adjacent structures with EDE-TECD applied is established， and using the optimization criterion of maximizing the minimum damping ratio between adjacent structures， a numerical search method is employed to obtain the optimal inertial mass ratio and damping ratio for the two-degree-of-freedom adjacent structure system with EDE-TECD. An analysis of the optimal inertial mass ratio is conducted， leading to a design process for the optimal parameters in the practical application of EDE-TECD. Additionally， the vibration reduction performance of adjacent structures with either EDE-TECD or linear viscous dampers is compared. Finally， the influence of structural stiffness degradation on the vibration reduction performance of EDE-TECD is studied. The results show that the optimal inertial mass ratio obtained through numerical search may be negative. Increasing inertial mass ratio does not always improve the damping ratio of the structure’s lower modes. Under 10 sets of earthquake wave tests， the optimized EDE-TECD significantly reduces the relative displacement of adjacent structures under seismic action， with the peak vibration reduction rate averaging 64.79%， which is 8.42% higher than that of linear viscous dampers. And under the El Alamo earthquake wave， when the structure’s stiffness is reduced by 10% to 40%， the maximum decrease in the peak damping rate of EDE-TECD is only 6.29%， and the structure can still maintain good damping performance.
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SHAN Bo1，2?，TANG Shuaihao1，ZENG Wei3，QIN Peicheng1，FU Xinlin4
Abstract:A series of explosive thermal spalling tests at elevated temperature and compression tests after high temperature were conducted on coir fiber reinforced ultra-high performance concrete （UHPC） by using an electric furnace in this study， aiming to shed light on the influence of the length and volume dosage of coir fiber on the fire resistance of UHPC exposed to different high temperatures. The results indicate that incorporating 1% of coir fibers with a length of 2 cm in UHPC can effectively suppress the high-temperature spalling. Microscope analysis reveals that a tangential pore network is generated between coir fibers and UHPC matrix due to shrinkage， decomposition， and carbonization of coir fibers at high temperature， which provides channels for the escape of internal water vapor as well as improving the thermal spalling resistance of UHPC. At 200 ℃， 400°C， 600 ℃， and 800 ℃， compressive strength and elastic modulus of UHPC， incorporating 1% of coir fibers with 2 cm long， significantly decrease with an increase in control temperature. Also， within the range of the control temperature， the ratio of the axial compressive strength to the cubic compressive strength varies between 0.62 and 0.92. On the other hand， compressive strength and elastic modulus decrease with the increasing volume dosage of coir fiber under the same control temperature， and the ratio of uniaxial compressive strength and cubic compressive strength varies with control temperatures. In terms of the improvement effect on fire resistance of UHPC， coir fiber is superior to steel fiber and is comparable to jute and flax fibers. Based on the test data and the existing formula， a special formula is proposed for evaluating the residual compressive strength of coir fiber reinforced UHPC exposed to high temperatures.
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WANG Hongjun1，2，REN Xiaodan1?，XIAO Shaowen2，TANG Mingsheng2
Abstract:To facilitate engineering applications and quantitatively describe the damage level of concrete components， referring to the constitutive model of concrete mentioned in Appendix C of the current Chinese standard “Code for Design of Concrete Structures” GB/T 50010—2010， this paper proposes a damage assessment method for concrete components based on material damage. That is， the damage level of the component is defined according to the values of the damage evolution parameter. It is specified that when the damage evolution parameter dc（t） is less than the damage evolution parameter dc（t），r corresponding to the peak strain of concrete εc（t），r， the concrete component is in a non-damaged state （Level L1）； when the damage evolution parameter dc（t） is greater than the damage evolution parameter dc（t）u corresponding to the strain of concrete εc（t）u， the concrete component is in a severely damaged state （Level L6）； when the damage evolution parameter dc（t） is between the two values， the damage state of the concrete component （Levels L2 to L5） is evaluated by the linear interpolation method. To verify the rationality of this method， a refined model of 18 beams and 2 columns was established using the ABAQUS software， and numerical analysis were conducted. The simulation results show a good agreement with the test results. According to the damage assessment method proposed in this paper， most of the beam components under the peak load and the column components under the yield load are in a severely damaged state （Level L6）. However， when using the damage assessment method based on the compressive strain of concrete as mentioned in the “Standard for Performance-Based Seismic Design of Building Structures” T/CECA 20024—2022， most of the components are in a moderately damaged state （Level L4）， while a minor portion of the components are in a relatively severe damaged state （Level L5）. From a macroscopic perspective， the damage assessment method for concrete components based on material damage proposed in this paper is more consistent with the actual expectations for evaluating the damage of concrete components and has a certain reference value.
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RAN Mingming1，2，LI Wei2，XIONG Feng1，2?，ZHANG Dongdong2，KOU Guangyun2
Abstract:The structural performance of modular buildings depends largely on the overall performance of their joint connections. This paper takes bolt-connected vertical joints of fully assembled modular construction-reinforced concrete （FAMC-RC） as research objectives， and a series of out-of-plane uniaxial tensile tests are conducted out on 10 groups of full-scale specimens of individual bolted vertical joints. The results show that under the action of tensile loading， the vertical joint may exhibit failure modes such as eccentric bending failure of a beam， punching shear failure of the plate， combined flexural and punching shear failure of the plate， and shearing failure of the plate. The damage process mainly undergoes four stages of prestressing loss， elastic loading， elastic-plastic development， and brittle damage. The mechanical properties of the joints are influenced by the distance D1 to the ribs， the length L of the connecting wall， and the embedded steel plate. The presence of ribs contributes to improving the out-of-plane bearing capacity of the joints， and the enhancement effect of the rib decreases with the increase of D1. The length L of the connecting wall is sufficient to make the punching cone fully carried out， and the punching ring is complete. The embedded steel plate in the joint region can obviously increase the bearing capacity， deformation capacity， and stiffness of the test specimen， but the increase in the size of the embedded part does not have a significant effect on the mechanical properties of the test specimen. Based on the above test results， the project suggests that： the distance D1 from the joint to the rib should be less than 485 mm， the length L of the connecting wall should be more than D1+300 mm， and， to reduce the amount of material， the V1-shaped embedded part is preferred. In this paper， for the punching damage mode， considering the concrete plate， reinforcement， and embedded steel plate of the three common anti-punching roles， a bearing capacity formula is proposed for the joint punching damage. The comparison with the test value concludes that the calculation formula is conservative. Taking into account the greater variability of the concrete material， the formula of the security reserve is high， and the calculation method is basically reasonable.
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HOU Xiaoqiang1，3?，ZHENG Jiale1，WANG Xinfei1，YANG Rui1，GUO Fuyun2，3，HOU Baosheng4
Abstract:To solve the problem of brittle failure at the rigid connection of the traditional h-shaped anti-slide pile beam， a structural optimization scheme was proposed， which simplified the multi-time super-static structure into an inclined “simply supported” structure and proposed the h-shaped inclined beam bearing anti-slide pile. Based on the Winkler elastic foundation beam theory and the structural force degree shift method， the analytical model was established by using the numerical analysis and numerical simulation methods. The results show that the theoretical calculation of the analytical solution is in good agreement with numerical simulation results， which proves the rationality of the calculation model. Compared with the traditional h-shaped pile， the optimized structure has significant advantages， that is， the bending moment at the connection between the rear pile and the beam is greatly reduced， the bending moment at the top of the pile of the front pile is completely released （the reduction is 0）， the shear force of the beam is significantly reduced， and the stress concentration phenomenon at the connection is avoided. From the analysis of key geometric parameters， it can be seen that with the increase of the angle of the oblique beam， the internal force and deformation of the oblique beam and the rear pile decrease， and with the increase of the distance between the front and rear piles， the internal force and deformation of the front pile decrease， and the mechanical performance of the system is better.
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SUN Keqiang1，2，LI Jinfeng1，HUANG Chuting1，LI Qirong2，ZHOU Suhua1?，LIU Xiaoming1
Abstract:Due to the influence of terrain and climate， the risk of highway slope disasters in Meizhou City is prominent. This study focuses on a 500-meter range on either side of the existing mainline highways in Meizhou， selecting eight evaluation factors—elevation， slope， curvature， lithology， NDVI， TWI， annual average rainfall， and maximum monthly rainfall—to construct a highway slope disaster susceptibility index evaluation system. Based on historical highway slope disaster data， a Bayesian network model is established to predict the susceptibility of highway slopes to disasters and further to analyze the distribution characteristics of landslide hazards under different rainfall scenarios. The conclusions are as follows： 1） The Bayesian network model for highway slope disaster susceptibility evaluation achieves an AUC of 0.832， indicating good reliability. Additionally， the SHAP values from the Bayesian network model show that lithology， slope， and maximum monthly rainfall are the three most influential factors affecting highway slope disasters in Meizhou City. 2） Considering three rainfall scenarios （1-in-10， 1-in-50， and 1-in-100-year events）， the areas of extremely high-risk regions gradually increased， accounting for 13%， 19%， and 22%， respectively. 3） Based on web scraping tools to retrieve social media data， all historical highway slope disaster cases in Meizhou are located in regions classified as high and extremely high hazard levels. The findings of this study provide a valuable reference for the prevention and control of highway slope disasters in Meizhou City.
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XIN Ren1，2，ZHAO Da1，2，WANG Ling1，3?，XU Shengjun4
Abstract:To analyze the precision of the integrated 3D point cloud reverse modeling （IPCRM） method in generating three-dimensional models of thin-thickness steel members， locally deformed angle steels are taken as the research objects. Three-dimensional point cloud models of locally deformed angle steels are established using the SfM （structure from motion）-MVS （multi-view stereo） algorithm， and the surface models of locally deformed angle steels are generated with the help of reverse engineering technology. Special attention is placed on model precision verification experiments. The results show that： the relative errors of all surface shape characteristic parameters are within 8% confirming the conformity of the models； there is no significant difference between the four angle steel models and the actual angle steels （P value， P=0.99）， and angle steel thickness has no significant influence on model precision （P value， P=0.95）. These conclusions hold at a 95% confidence level （significance verification）. The research results provide a basis for subsequent algorithm optimization and the rational use of this method for local deformation damage detection and bearing performance evaluation of steel members.
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XU Ying1，2?，JIANG Xinfeng1，2，JIANG Xuelei1，2
Abstract:To achieve precise positioning of steel bars inside concrete structures and accurate detection of early corrosion status， this article introduces a terahertz reflectance spectroscopy technique and systematically explores its potential application in non-destructive testing for structural corrosion assessment. The research results indicate that this technology can achieve precise positioning of steel bars inside the structure and accurate measurement of the thickness of the protective layer， with a positioning accuracy within 1.2 mm of the steel bars. Meanwhile， the minimum measurable thickness of the corrosion layer reaches 45 μm， which is sufficient for effective detection of early corrosion of steel bars. Terahertz technology can achieve quantitative visualization imaging of the thickness of the protective layer and corrosion layer within the scanning area， eliminating the influence of uneven distribution of protective layer thickness and providing an innovative and efficient method for early corrosion characterization of reinforced concrete structures.
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ZHANG Yongjie，FAN Hai，OUYANG Jian?，DENG Jin，YANG Yanzhen，LIU Xiaofan
Abstract:The strong permeability， high porosity， and easy disintegration of granite residual soil cause serious erosion in the surface layer of the slope. Both biocementation and plant roots can be used for shallow slope protection. This study conducted single biocementing， single root， and joint combined reinforcement tests to investigate the effects of root content and the biocementing time on permeability， water retention， disintegration， and shear properties. Then， the hydraulic properties of granite residual soil reinforced by biocementation joint root systems were systematically analyzed. The results showed that single root reinforcement primarily improved the shear characteristics of granite residual soil， but also increased its permeability. Single biocementation significantly improved the permeability， water retention， disintegration， and shear properties of granite residual soil； however， too many cementing times may weaken its shear resistance properties. The incorporation of roots under co-reinforcement increased the permeability of granite residual soil， while substantially improving the disintegration and shear properties， which was more pronounced with higher root incorporation. The disintegration process of the specimens under joint reinforcement was mainly divided into three stages， and the improvement effect of cohesion was much higher than the internal friction angle. The combined reinforcement of biocementation and root exhibits a significant synergistic effect， with biocementation playing a critical role in enhancing the hydraulic properties of granite residual soil， while root systems assist in regulating water movement.
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Numerical simulation study on transition effect of linear slope ratio on wind field of terrain model
JING Hongmiao1，2，3?，ZHANG Yinxuan3，LI Weikang3，SU Fang4，ZHAO Zhiheng3，ZHAO Wanru3，ZHANG Zheng3
Abstract:To accurately obtain the influence of slope transition sections on the wind field characteristics of the terrain model， this study used the large eddy simulation （LES） method to conduct numerical simulation of wind field characteristics in the transition section of slopes with different slope ratios. At the entrance of the computational domain， numerical turbulent flow was generated by the narrow band synthesis random flow generation （NSRFG） method . The slope ratio ξ（=L/h） of the slope transition section was defined （ξ takes the values of 0， 1， 2 and 3， where h is the slope height and L is the slope length）. The results show that when the incoming flow reaches the slope transition section， a backflow is formed at the bottom of the transition section， the wind speed is significantly reduced， and the turbulence intensity is also reduced. When the incoming flow reaches the top of the slope transition section， the wind speed increases significantly， and the turbulence intensity also increases. When the incoming flow passes through the slope transition section， the mean wind speed profile gradually returns to the same as that of the inlet. In addition， the larger ξ can result in better transition effect， lower vortex shedding frequency， more uniform vortex shedding frequency at different heights， smaller variation in wind speed amplification factor， and larger turbulence integral scale. The transition effect is best when ξ=3， and it returns to the same as the inlet wind speed profile at x/h=2， and the wind speed amplification factor returns to 1 at the more advanced position. This study can provide a reference for the design of boundary transition sections of terrain models for wind field characteristic measurement.
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CHEN Fubin，ZHU Yuzhe，ZUO Xiaowei?
Abstract:To investigate the wind load characteristics of rectangular sections with a small side ratio （D/B<1.0）， a series of three-dimensional models （with fixed cross-sectional area and side ratios ranging from 0.25 to 1.00） were adopted. First， the space-averaged large eddy simulation （LES） method was used to obtain the aerodynamic coefficients of four models with distinct side ratios， as well as the correlation coefficients of horizontal fluctuating wind pressure across different facades of the models. Subsequently， the influence of the side ratio on the product time-history peaks and phases of wind pressure at the side-surface measurement points was compared and analyzed. Finally， based on the dynamic mode decomposition （DMD） method， a reduced-order model capable of extracting dominant modes and reconstructing the wind pressure field was established， and the wind pressure fields of models with different side ratios were analyzed. The results indicate that a decrease in the side ratio affects the separation and reattachment of flow on the model’s side surfaces， altering the wind load action mechanism and significantly reducing the horizontal correlation of fluctuating wind pressure （with the 0.25 side ratio model exhibiting the most pronounced effect）. The transition point of wind pressure fluctuation characteristics is located approximately 0.6B from the side-surface reattachment region； the wind pressure time histories at the upstream and downstream of this transition point show opposite phases and negative correlation. The first four modes extracted via the DMD method can accurately reconstruct the flow field， thereby clarifying the random wind pressure field of small side ratio models. This study provides a reference for relevant flow control and structural design.
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YU Xiaoqing1，2，CHEN Yan3，HU Qian4，HE Xi4，LIU Zhanghong2，GUO Chenghui5，YANG Wei1，6，7?
Abstract:Taking phosphogypsum from a tailings reservoir in Guizhou as the research object， a comparison with planting soil standards revealed problems such as strong acidity， severe salinization， and poor fertility. Improvement experiments were conducted using quicklime， straw biochar， earthworm manure， and nutrient soil to obtain the optimal improvement scheme. Based on the improved phosphogypsum， studies on phytoremediation and microbial remediation were carried out to screen plants with strong stress resistance and the best fluoride pollution enrichment capacity， as well as to cultivate microorganisms with the best phosphorus pollution fixation and transformation effects. According to the experimental results， plant-microbial combined remediation experiments were conducted to compare the enrichment capacity of plants and microorganisms for pollutants， the adaptability of plant growth capacity， and the improvement effect on the physicochemical properties of phosphogypsum，so as to clarify the synergistic effect between plants and microorganisms. Finally， a plant-microbial combined remediation scheme for in-situ control of phosphogypsum pollution and ecological remediation is proposed. The results showed that when quicklime， straw biochar， vermicompost， and nutrient soil are added at concentrations of 1.0%， 1.0%， 10.0%， and 10.0%， respectively， the pH of phosphogypsum increases from 2.16 to 4.75， organic matter content increases by 5.3 times， and electrical conductivity decreases to 56.4%. Phytoremediation experimental studies found that ryegrass had the optimal stress resistance and pollutant enrichment effect； microbial remediation experiments revealed that the five strains isolated and screened from phosphogypsum all have the ability to fix and convert phosphorus. After identification， they were identified as the chitinophaga sp.， Pseudomonas sp.， Xanthomonas sp.， Variovorax paradoxus sp.， and Delftia sp.. The optimal inoculation amount was 5×107 CFU/300 g， which could reduce the phosphorus concentration of phosphogypsum leachate to 23.3%. Plant-microbial combined remediation experiments found that the addition of microorganisms had a growth-promoting effect on plants. The total phosphorus and maximum fluoride adsorption increased by 39.9% and 78.1% respectively； furthermore， the phosphorus-fixation ability of microorganisms increased by 123.2%.
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LAI Yuanwen，ZHANG Shiqi，GE Yuchen，WANG Shuyi?
Abstract:Sudden metro service interruptions can result in train delays and passenger congestion at stations. This， in turn， will present significant challenges for passenger evacuation and emergency management. To evaluate the performance of urban public transport networks under such disruptions， this paper proposes a composite network resilience assessment method based on resilience theory， which considers passengers’ multi-path decision-making for travel in the event of sudden disruptions. Firstly， the construction of an urban public transport composite network model， which considers the “one-to-many” coupling mode of stations， is based on the combination of passenger flow and geographic information data. This model is used to determine the network interruption intervals under different faulty stations. Secondly， the inter-layer traffic distribution of the network is carried out， taking into account the passengers’ multi-path decision-making in emergencies and calculating their travel times. Ultimately， an evaluation framework for the resilience of the composite network is established based on the composite network performance function. Furthermore， the network resilience levels under disparate interruption scenarios are contrasted through case analysis. The findings indicate that there are notable discrepancies in the network resilience levels under varying station failures. Among these discrepancies， the interruption interval of the network， the passenger flow volume of the lines， and the conditions of the subway-coupled bus stations will all influence the network resilience under interruptions. The resilience assessment method for urban bus composite networks proposed in this study can serve as a reference for the development of emergency response plans in the event of sudden disruptions.
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LIU Chenhui1，2，3?，DENG Jierong1，LIU Ling4
Abstract:While smart card data （SCD） collected from automatic fare collection （AFC） systems accurately records when and where people travel， they do not directly convey the trip purposes or activity types. In this study， we propose a method that integrates station clustering with an LDA model to uncover latent activities from urban rail transit passenger mobility data. First， we classified the stations into eight categories—employment，residential， mixed-use residential-employment， commercial centers， tourist attractions， composite hubs， external hubs， and ridership cultivation stations—using a constrained-seed K-means algorithm， based on demographic characteristics， ridership patterns， and the distribution of POIs around each station. Second， an LDA model is developed based on four key attributes： exit time， activity duration， origin station type， and destination station type. The model successfully identifies five primary activity types： shopping-related， work-related， home-related， tourism， and other. Furthermore， these patterns are divided into several subtopics， each distinguished by specific temporal and spatial characteristics， providing the theory support for deeply figuring out holiday travel patterns of urban rail transit passengers.
Vol, , No.1, 2026
Special Issue
Virtual Special Issue中国科学引文数据库来源期刊(CSCD)
第二届国家期刊奖百种重点期刊
教育部中国高校百佳科技期刊
湖南省十佳科技期刊
