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28 August 2024, Volume 50 Issue 4 Previous Issue    Next Issue

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Materials Science and Engineering

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Microstructure and properties of AlCoCrFeNi2.1 high entropy alloy modified by deformation heat treatment WANG Peng-hui, ZHANG Xiao-bo 2024, 50 (4):  1-5.  Abstract ( 158 )   PDF (2366KB) ( 186 )   Save High-entropy alloys have become a focal point in the field of materials in recent years due to their combination of high strength, toughness, high-temperature mechanical properties, oxidation resistance, and corrosion resistance. Eutectic high-entropy alloys combine the advantages of eutectic alloys and high-entropy alloys, making it possible to cast large-scale components. The mechanical properties of the alloy are regulated by cold rolling and annealing, and the changes inmicrostructure organization and mechanical properties of the eutectic high-entropy alloy after annealing at different temperatures are investigated by XRD, SEM, EDS, and tensile testing machine. The results showed that the tensile strength of the alloy is abnormally improved after 30% cold rolling, while the elongation plummeted. After annealing at temperatures of 800 ℃, 900 ℃, and1 000 ℃ after 30% cold rolling, the organization gradually changes from partial recrystallisation to complete recrystallisation, accompanied by slight grain growth. After annealing at 800 ℃, there are deformed large grains and recrystallised small grains, and a variety of reinforcement mechanisms work in a coordinated way to make the tensile strength and elongation to 1 272 MPa and 12.39%, respectively. References | Related Articles | Metrics

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Microstructure and properties of FeCrMnAlxCu(2－x) high-entropy alloys LI Da-peng, DENG Guo-hui, WU Zhi-guo, XUAN Rui 2024, 50 (4):  6-11.  Abstract ( 82 )   PDF (4967KB) ( 49 )   Save FeCrMnAlxCu(2－x)(x=1.3, 1.4, 1.5, 1.6, 1.7) high-entropy alloys (HEAs) was prepared by vacuum arc melting technology, and the influence of Al and Cuon the microstructure, mechanical properties, and tribological behavior of FeCrMnAlxCu(2－x) HEAs was investigated. The results revealed that FeCrMnAlxCu(2－x) HEAs is BCC solid solution structure. The microstructure of the alloys consist of dendritic structure. With increasing x, the yield strength gradually increase and reach a maximum value of 1 092.31 MPa at x=1.5. Both compressive strength and deformation rate exhibit a decreasing trend with increasing x, reaching their maximum values at x=1.3, which are 1 517.84 MPa and 43.36%, respectively. The FeCrMnAl1.7Cu0.3 HEA exhibit a maximum microhardness of 559.9 HV. The minimum wear rate is found to be 4.70×10－6 mm3·N－1·m－1. As x increased, the dominant wear mechanisms in the alloy are primarily abrasive wear, adhesive wear, and oxidative wear. References | Related Articles | Metrics

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Effect of co-doped La3+ and excessive concentration Sr2+ on the luminescence properties of Sr1.96Eu0.04SiO4 WANG Wei, ZHU Hong-bo, WU Mei 2024, 50 (4):  12-16.  Abstract ( 55 )   PDF (2577KB) ( 43 )   Save Sr1.96－xEu0.04SiO4∶xLa3+(x = 0,0.01,0.02,0.03,0.04,0.05) and Sr1.94+yEu0.04La0.02SiO4∶ySr2+(y=0,0.05,0.10,0.20,0.30) were synthesized by high-temperature solid-state method. The structure and luminescence properties of the phosphors were characterized by X-ray powder diffractometer and fluorescence spectrophotometer. The results showed that the XRD of the phosphors are consistent with the Sr2SiO4 standard card PDF 39-1256, and no impurity phase is produced. The luminescence intensity of phosphors Sr1.96Eu0.04SiO4 is enhanced by doped La3+, and the position of emission peak remain unchanged. The phosphors show the strongest luminescence intensity when the doped concentration of La3+ is 2% (molar fraction). The luminescence intensity of Sr1.94Eu0.04La0.02SiO4 can be further enhanced by doped series of excessive concentrations of Sr2+ without changed the position and shape of the emission peak. When Sr2+ is excessive 10%, the luminescence intensity of the phosphors is the strongest. The broadband emission spectrum of the phosphors can be fitted as two independent emission peaks, which correspond to Eu2+ 4f65d1→4f7 transition. The intensity of two emission peaks changes regularly with increasing ventilation volume, which give rise to the luminescence color of phosphors changes from green to yellow. References | Related Articles | Metrics

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Preparation and mechanical properties of phenolic resin based secondary porous foam carbon JIA Jian-gang, QI Wang-qian-duan-zhi, WANG Ming, YOU Xin-ya LIU Di-qiang, ZANG Shu-jun 2024, 50 (4):  17-22.  Abstract ( 62 )   PDF (5476KB) ( 67 )   Save Using phenolic resin as carbon source precursor and NaCl powder along with a self-made salt ball as a pore-forming agent, high-strength multi-stage porous foam carbon was prepared by template method. The pore structure of foam carbon was regulated by the salt ball size and NaCl powder, and the effect of pore-forming agent salt ball size on the pore structure and mechanical properties of foam carbon was studied. The results showed thatwhen the volume percentage of salt ball is the same (salt ball accounted for 60 % of the volume of foam carbon embryo), with the increase of salt ball size, the uniformity of salt ball pores in multi-stage porous foam carbonis decreased, and its ligament gradually become thicker with the increase of salt ball size. There are numerous NaCl powder pores and bubble pores inside the salt ball pores and on the ligaments, which are interconnected to form an open-pore structure. The salt balls of different sizes do not significantly affect the density of the hierarchical porous carbon foam, which remain at approximately 0.2 g/cm3. However, the compressive strength decreases with the increase of salt ball size. The maximum compressive strength and specific compressive strength of the foam carbon with the particle size of 14~35 are 4.4 MPa and 22 MPa·cm3/g, respectively. References | Related Articles | Metrics

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Basalt fibers modified by silane coupling agents and its influence on the mechanical properties of concrete SHI Xu-dong, WANG Jin-man, CHAI Xu-hui, YANG Qiang-bin 2024, 50 (4):  23-28.  Abstract ( 66 )   PDF (2545KB) ( 70 )   Save In order to improve the mechanical properties of the composite materials of concrete with basalt fiber, the ethyl orthosilicate, which was a relatively cost-effective silane coupling agent, was used to modify the surface of basalt fibers. These modified fibers were then introduced into concrete as the reinforcing phase to improve the mechanical performance of the concrete material. The microstructure of both fibers and concrete was studied by scanning electron microscopy. The influence of basalt fibers on the rheological properties of the fresh concrete was studied. The mechanical strength of concrete was assessed by three mechanical strength indicators: compressive strength, splitting tensile strength, and flexural strength. As a result of this, the addition of basalt fibers reduces the variability of the fresh concrete. After modification, the introduction of basalt fibers into the concrete results in a tighter interface boundary adhesion between basalt fibers and concrete. At the optimal addition amount of 4 kg·m－3, the compressive strength, splitting tensile strength, and flexural strength of concrete composite materials increases by 6.83%, 21.46%, and 12.7%, respectively. References | Related Articles | Metrics

Mechanical Engineering and Power Engineering

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Mesh contact impact analysis of involute beveloid gear LIU Yong-ping, REN Zhong-tao, DONG Chang-bin, WEI Yong-qiao, WEI Shuai 2024, 50 (4):  29-35.  Abstract ( 54 )   PDF (5402KB) ( 57 )   Save Based on the elastic contact dynamics theory and the physical model of gear transmission, the mesh impact problem of involute variable-thickness gears is analyzed, and the full tooth mesh contact impact model of variable-thickness gears is established; by simulating the gear mesh contact state, the gear mesh area is discussed, and the contact collision analysis is carried out by using LS-DYNA software to study the impact force and impact stress with speed and impact position respectively. The results show that the speed and impact position have a significant influence on the impact force. The results show that the rotational speed and impact position have a great influence on the impact force and impact stress, and the maximum impact stress is mainly concentrated near the top of the tooth and the large and small ends of the gear teeth; the larger the rotational speed is, the greater the difference in impact stress between the loaded and unloaded surfaces of the gear teeth. References | Related Articles | Metrics

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Rolling bearing fault diagnosis of wind turbine based on OVMD-RF method ZHENG Yu-qiao, LI Hao, WEI Tai 2024, 50 (4):  36-42.  Abstract ( 50 )   PDF (1225KB) ( 31 )   Save The bearings of the wind turbine are subjected to alternating stresses and shock loads during operation, leading to nonlinear, non-stationary, and noisy vibration signals, thus rendering conventional feature extraction insufficient. Aiming at the inherent defects in the wind turbine bearings failure message processing and feature extraction for wind turbine bearing fault diagnosis, a novel method has been proposed on the basis of the optimal Variational Modal Decomposition combined with a random forest algorithm. Firstly, The technique utilizes the sooty tern optimization algorithm to conduct a search optimization of the values in the variables for the variational modal decomposition. Subsequently, the method with optimized parameters is employed to decompose the vibration signal of rolling bearing signals to obtain modal components. Finally, the peak value, kurtosis, and envelope entropy are applied to construct the fusion feature training set and input them into the random forest classifier to realize fault recognition. The results of the case analysis demonstrate the efficacy of the proposed methodology to identify faults in achieving a fault recognition accuracy of up to 100% for wind turbine bearing faults, facilitating accurate fault discrimination. References | Related Articles | Metrics

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Multiaxial fatigue life modeling based on stress gradient and additionalhardening LIU Jian-hui, WANG Jie, HUA Fei-long, ZHAO He 2024, 50 (4):  43-49.  Abstract ( 35 )   PDF (2671KB) ( 32 )   Save Considering the influence of non-uniform stress field and non-proportional additional hardening on the fatigue damage evolution process, a fatigue life prediction model for multiaxial notched specimens is established to solve the problem that the stress gradient and additional hardening effect are not considered in Manson-Coffin equation. Firstly, considering the physical mechanism of crack initiation and propagation, the location of the critical plane is determined by using the maximum shear strain amplitude as the damage parameter based on the coordinate transformation principle and the critical plane theory. Secondly, the normal stress and shear stress on the critical plane are normalized, and the new equivalent stress gradient factor is determined considering the multiaxial stress concentration factor and stress gradient influence index. Meanwhile, taking into account the influence of phase difference, path non-proportion, and material non-proportion on fatigue life, a new non-proportional additional hardening factor is proposed. Finally, a new multiaxial fatigue life prediction model is proposed based on the Manson-Coffin equation. The prediction life of the proposed model, Manson-Coffin equation, LV model, and FS model are compared with the experimental results. The comparison results show that the prediction accuracy of the proposed model is better than the other three models. References | Related Articles | Metrics

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Stability analysis of drum brake based on interval parameters HE Ning, ZHANG De-long, ZHANG Qing-hua 2024, 50 (4):  50-54.  Abstract ( 32 )   PDF (1516KB) ( 10 )   Save To suppress brake squeal, a stability and reliability analysis of drum brake with interval uncertainty parameters is presented based on the response surface method, finite element complex eigenvalue analysis, and theories of reliability. In the proposed method, Young’s modulus of the friction plate, brake shoe, and brake drum is treated as uncertain parameters, with the interval parameters describing the uncertainties in the braking system. Then, a response surface approximation model of the coefficient with interval uncertainty parameters is built up in a drum brake, achieving model parameterization for brake stability analysis. Furthermore, by combining interval analysis with reliability analysis, the drum brake system model uses the proposed method, the statistical regularities of the drum brake system with the uncertainty of Young’s modulus are analyzed, and the results show that enhancing the control over the Young's modulus of the brake shoe and friction plate can improve the vibration stability of a brake system effectively and reliably under uncertainty conditions. Reference value is provided for the suppression of brake noise in engineering. References | Related Articles | Metrics

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Mechanical characterization of the whole lifting process of the tower crane ZHANG Dui-xue 2024, 50 (4):  55-59.  Abstract ( 37 )   PDF (1051KB) ( 20 )   Save Aiming at the stability of tower crane lifting process, this study takes a certain type of flat-top tower crane as the research object, and carries out the static mechanics and transient dynamics research of the whole lifting process. Firstly, the finite element static analysis is used to solve the relationship between the tower crane’s displacement response at different lifting positions and different lifting weights under the static wind condition and normal working condition, and the results show that: the static analysis shows that the tower crane has similar amplitude and trend of change under the static wind condition and normal working condition, and the wind load has a greater contribution to the tower crane's displacement response; under the consideration of the inertial force of tower crane, based on the transient dynamics analysis, the tower crane's mechanical performance is affected by the transient dynamics analysis, which is the most important factor in the mechanical performance of tower crane. Under the action of tower crane inertia force, based on the transient dynamics analysis, the maximum deformation response of the tower crane under different lifting acceleration is unfolded, and the results show that: the difference of the maximum displacement response is 71.8 mm between the lifting at 60 m amplitude and 30 m amplitude, and the difference of the average displacement response is 63.4 mm, 63.6 mm, 64 mm, and 64.1mm, both of which have similar fluctuation amplitude and trend, indicating that the tower displacement response under the slow lifting condition has a similar change amplitude and trend. Both of them have similar fluctuation amplitude and change trend, indicating that the tower displacement response is not sensitive to the lifting position in the case of slow lifting; in addition, both of them show the undulation trend, which indicates that there is an obvious shaking phenomenon of the tower crane in the process of lifting. References | Related Articles | Metrics

Chemical Industry and Light Industry

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Research on corrosion rate prediction of buried pipeline based on PCA-BPNN model YU Yang, SUN Dong-liang 2024, 50 (4):  60-68.  Abstract ( 45 )   PDF (1741KB) ( 23 )   Save In order to predict the corrosion rate of buried pipelines more accurately and reliably, the method integrating PCA analysis and BP artificial neural network simulation is studied. A buried oil pipeline of an oil and gas company in Shaanxi Province was selected to construct an 8-dimensional external corrosion index system, and the simulation training results were obtained in the PCA-multi-hidden layer BPNN model. The external corrosion index system was reduced to three dimensions by PCA pretreatment, so as to reduce the coupling influence brought by multi-element information. The BPNN model with the optimal hidden layer parameters was trained to predict the corrosion rate. The accuracy of the predicted value was obtained, and it was found that the number of accuracy greater than 95% of the improved method was 2.5 times that of the single BP method. In order to test the robustness of the PCA-multi-hidden layer BPNN method, an additional set of 20 groups of data are substituted for verification, reaffirming that the error of PCA-multi-hidden layer BPNN model is smaller and can better meet the needs of practical engineering. References | Related Articles | Metrics

Automation Technique and Computer Technology

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Adaptive fault-tolerant control of multi-quadcopter UAV formation WANG Jun, LI Ang 2024, 50 (4):  69-76.  Abstract ( 64 )   PDF (2629KB) ( 66 )   Save Aiming at the problem that the quadrotor UAV is affected by the actuator failure during formation control and the resultant tracking errors between UAVs, the fixed parameters controlled by the traditional PID cannot be applied to the complex environmental challenges faced by the quadrotor UAV. Consequently, a Fuzzy adaptive PID fault-tolerant controller and a sliding mode cooperative controller for multiple UAVs are devised. Firstly, the system model of UAV with Actuator Failure is established, with a reference trajectory set for the leading UAV. Through the designed fuzzy adaptive PID controller, the UAV experiencing actuator failures is guided to track the specified trajectory. Secondly, based on the sliding mode control theory, a formation cooperative controller, the controller is designed to make the distance error between the follower UAV and the leader UAV close to zero, achieving the desired formation. Finally, the comparison results of simulation experiments show that the proposed method exhibits minimal overshoot and strong robustness, thereby yielding a favorable control effect on the quadrotor UAV. References | Related Articles | Metrics

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Research on segmentation and edge refinement of melanoma image ZHAO Hong, WANG Ao-long, ZHANG Chen-peng 2024, 50 (4):  77-85.  Abstract ( 52 )   PDF (4121KB) ( 28 )   Save Segmentation of melanoma image has important clinical value in the diagnosis and treatment of skin diseases. However, due to the lack of annotation and serious category imbalance of data set, the accuracy of the segmentation map is low and the edge is rough. Therefore, a melanoma segmentation and edge refinement method is proposed, which can be implemented in three stages. In the first stage, after classifying the melanoma data set, multiple hierarchical class activation maps are extracted and processed by weakly supervised method. In the second stage, a UNet model is built to segment malignant samples in melanoma data set. In the third stage, the edge refinement of the results of the second stage is carried out by using the enhanced and overlaid class activation map obtained in the first stage. Experimental results on the ISIC melanoma dataset show that after three stages of processing, the segmentation map has finer edges, with a mean intersection over union value of 86.04%, a Dice similarity coefficient of 0.937, and a Jaccard similarity coefficient of 0.885. References | Related Articles | Metrics

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Community detection algorithm based on maximal clique of network nodes LU Peng-li, YANG Ya-lei 2024, 50 (4):  86-93.  Abstract ( 40 )   PDF (3561KB) ( 21 )   Save Community structure detection is instrumental in revealing the structure-function properties of complex networks. The existing community detection algorithms suffer from resolution limitations, node uncertainty, and the need for prior parameters in their research process. A community detection algorithm based on the maximal clique of network nodes (BMC) is proposed to solve these problems. The BMC algorithm sets the maximal clique of nodes in the network as the initial node cluster, and merges the node clusters by hierarchical clustering based on the proposed local similarity of the maximal clique and the local clique relationship, so as to mine the community structure in the network. Aiming at tackling the issue of node uncertainty in the mining process of community structure, the module membership degree is proposed through the modularity matrix to optimize the single neighbor nodes and overlapping nodes in the network. In order to verify the accuracy of the BMC algorithm for network community structure mining, experiments are conducted on five real network datasets with five algorithms for comparison. The experimental results obtained by the three measures show that the BMC algorithm accurately detects the community structure in the network. References | Related Articles | Metrics

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Design of a seven-core photonic crystal fibers with low crosstalk and nearly zero ultra-flattened dispersion FAN Shi-zhuo, HOU Shang-lin, LEI Jing-li 2024, 50 (4):  94-102.  Abstract ( 32 )   PDF (4094KB) ( 19 )   Save In this paper, a liquid-filled seven-core photonic crystal fiber with low crosstalk and nearly zero ultra-flattened dispersion is designed, and its dispersion, inter-core crosstalk, and bending loss are numerically simulated by the finite element method. Numerical simulation results show that the fiber not only achieves nearly zero ultra-flattened dispersion but also significantly suppresses inter-core crosstalk and bending loss. At wavelengths of 1.38 μm to 1.74 μm, the absolute value of dispersion is less than 0.5 ps/(km·nm), while the absolute value of dispersion slope is less than 0.02 ps/(km·nm2). The maximum value of inter-core crosstalk is lower than －84.09 dB/100 km in the C+L band and the bending loss is lower than the ITU-T recommendations of G.654 in a seven-core PCFs with a 125 μm cladding diameter. References | Related Articles | Metrics

Architectural Sciences

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Study on seismic responses and mitigation of multi-span simply supported beam bridges under near-fault ground motions LI Wang-ping, YANG Xiong, JIAO Ying-qian, PEI Yin-hai, SHI Yan 2024, 50 (4):  103-111.  Abstract ( 47 )   PDF (6521KB) ( 22 )   Save In order to study the seismic response and mitigation measures of a multi-span simply suppor-ted beam bridge under near-fault ground motion,a 4-span simply supported beam bridge was taken as theresearch object.Three groups of near-fault ground motions were selected,which respectively considerfling step effect,forward directivity effect,and no pulse effect,along with one group of far-fault seismicmotions for comparison.The seismic response and damage degree of key components such as main beams,piers,and bearings.It was found that the velocitypulse-type near-fault ground motion amplifies the displacement response in both longitudinal and trans-verse bridges,which not only increases the damage degree of the piers and bearings,but also increases thenumber of longitudinal collisions between beams and the peak value of collision force.Therefore,a com-bined seismic reduction system of Buckling-Restrained Brace(BRB)and viscous damper was put forward.The influence of the arrangement and parameters of a viscous damper on the seismic reduction effect is an-alyzed.The results show that the mitigation scheme effectively reduces the damage to piers and bearingsand reduces the longitudinal displacement of main beams.Arranging dampers between the main beam andits abutment is more conducive to the seismic control of a multi-span simply supported beam bridge.It issuggested that the viscous damping coefficient C between the main beams should be 3 000 kN·s/m,whilethe viscous damping coefficient C between abutment and main beams should be 4 000 kN·s/m,with thevelocity correlation coefficient a of 0.4. References | Related Articles | Metrics

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Experiment and numerical simulation of pile-anchor supporting slope considering top beam CHEN Chang-liu, DU Jiang-tao, YE Shuai-hua, TAO Hui 2024, 50 (4):  112-120.  Abstract ( 39 )   PDF (5842KB) ( 15 )   Save Relying on the example of pile-anchor supporting slope in Lanzhou Port Affairs District, the combined approach of wireless automatic monitoring and finite element software numerical simulation was employed to investigate the variations in internal forces and slope stability of the pile-anchor supporting at the stage of no top beam (filling process) and setting of the top beam (during the operation period). The results show that at the stage without top beam, as the height of the fill increases, the pile bending moment, anchor axial force, and slope displacement gradually increase. After the installation of the top beam, the pile bending moment and the anchor axial force can be effectively reduced. The axial force of the anchor rod has a strong restraining effect on the soil near the top of the pile with the most significant constraint effect observed on the top displacement of the slope. The influence of the displacement of the slope gradually decreases from the top of the slope to the bottom of the slope, which also significantly improves the side stability of the slope. With the mutual adjustment of the supporting structure and the slope soil stress during the operation period, the internal force and displacement of both tend to stabilize. This test provides a useful reference for the design, construction, and monitoring analysis of the pile-anchor-supported slopes in the northwest loess area. References | Related Articles | Metrics

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Numerical analysis of secant pile supporting deep foundation pit based on ABAQUS DONG He-ping, DONG Jian-hua, WU Xiao-lei 2024, 50 (4):  121-128.  Abstract ( 70 )   PDF (3197KB) ( 38 )   Save Based on ABAQUS numerical analysis software, the stiffness equivalent principle is used to equivalent the occlusive pile supporting a deep foundation pit. The deformation of the pit bottom heave during unloading, the displacement of the support structure, and the variations in axial force of support in the unloading process of foundation pit excavation are analyzed numerically. A comparative validation is conducted using actual monitoring data. The results show that the stiffness equivalent principle can effectively capture the deformation characteristics of the foundation pit. The deformation results of the supporting structure and the surrounding environment obtained by the numerical analysis are in good agreement with the actual monitoring values. Therefore, this method can serve as the guidance for the actual construction of the foundation pit. References | Related Articles | Metrics

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Optimum analysis of super deep circular foundation pit enclosure structure ZHAO Yi-xing, ZHAN Gang-yi, LI Min, LIANG Xin-huan CHEN Zhao-yang, SHI Yu-feng 2024, 50 (4):  129-134.  Abstract ( 33 )   PDF (2035KB) ( 9 )   Save Aiming at the design problem of an ultra-deep circular enclosure structure in Foshan City, a numerical simulation combined with field measurements is employed to analyze in light of the geological characteristics. The thickness and embedded depth of the retaining structure were optimized and analyzed, and the variation of the stability of the foundation pit with changes in the thickness and embedded depth of the retaining structure under the same conditions was discussed. The results showed that the excavation face was deep into the rock. The circular foundation pit has good self-stability. From an economic point of view, the enclosure structure should not be embedded in deep rock. Furthermore, it is demonstrated that a relatively thin ground connecting wall, with shallow embedment, can meet safety requirements with considerable safety margins when placed on a sufficiently rigid foundation. These findings offer valuable insights for relevant engineering projects. References | Related Articles | Metrics

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Numerical simulation study on bond-slip performance between FRP bar and cement slurry WANG Zheng-zhen, LIANG Jin-tian, DAI Guo-liang, ZHOU Yong JIN Gao-ming, WANG Jin-ke 2024, 50 (4):  135-141.  Abstract ( 42 )   PDF (3656KB) ( 17 )   Save In this paper, the bond-slip performance between FRP bar and cement slurry and the influence factors on the bond performance were studied by numerical simulation and indoor test. Cohesive unit the finite element software was used to simulate the interface bond slip between FRP bar and cement slurry, and the damage and destruction behavior of cement slurry was simulated by the concrete plastic damage model. The influence factors such as FRP bar type, diameter, and length on interface bond behavior, bond stress distribution, and failure mechanism was studied through controlled variable method. The results show that the bond performance of different types of FRP bars varies greatly. Increasing the bond length and diameter of FRP bar can improve the ultimate bearing capacity. During the loading process, the axial force of FRP bar is mainly distributed at the loading end. As the load increases, the increase in axial force of the FRP bar near the loading end is greater than that at the end of the bonding section. When the pull-out load reaches its peak, the interface bond unit is damaged, and the bond strength continuously decreases. As the bond slip curve enters the descending stage, the interface bond strength gradually fails and the specimen is completely destroyed. References | Related Articles | Metrics

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Imitative full internal force genetic algorithm for structural optimization of concrete-filled square steel tubular truss XIE Jun, GUO Fei, GUO Wei-tong, YAN Jie, WANG He-he, YANG Yong-zhu 2024, 50 (4):  142-146.  Abstract ( 45 )   PDF (613KB) ( 18 )   Save To address the structural optimization problem of concrete-filled square steel tubular truss with discrete variables, the imitative full internal force genetic algorithm was used to optimize the structural size of the member section aimed at minimizing the total cost of truss member. The imitative full internal force algorithm was introduced into the imitative full internal force genetic algorithm as an operator, and some initial populations were generated by the imitative full internal force algorithm to increase population diversity. Meanwhile, the penalty function of the traditional genetic algorithm was improved to enhance the optimization efficiency of the algorithm. Comparative analysis of two case studies demonstrates that the cost of the square steel tube concrete truss structure is reduced by 15%, 15% and 45%, 53% respectively by using the imitative full internal force genetic algorithm compared with the imitative full internal force algorithm and the traditional genetic algorithm. It is effective and feasible of the imitative full internal force genetic algorithm for optimizing the concrete-filled square steel tubular truss. References | Related Articles | Metrics

Scientific

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The Quasi-boundary regularization method for inverting the left boundary of fractional Schrödinger equation GAO Yin-xia, YANG Fan, ZHANG Cheng 2024, 50 (4):  147-152.  Abstract ( 48 )   PDF (574KB) ( 34 )   Save The problem of inverting the left boundary of the time-fractional Schrödinger equation in the unbounded region is studied, which is an ill-posed problem, meaning that the solution discontinuously depends on the measurement data. A quasi-boundary regularization method is used to solve this inverse problem, and its regularized solution is given. The error estimates between the regularization solution and the exact solution are derived under the priori and the posteriori regularization parameter selection rule. References | Related Articles | Metrics

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GMA system and parameter identification for a class of microbial continuous fermentation process ZHAO Ya-zhi, XU Gong-xian 2024, 50 (4):  153-158.  Abstract ( 56 )   PDF (545KB) ( 32 )   Save The mathematical modeling and parameter identification of a class of microbial continuous fermentation processes are studied here. The mathematical model of the GMA system for the continuous microbial fermentation process is proposed, and its mathematical properties of the system are also presented. The parameter identification model is constructed by minimizing the squared error sum between the experimental steady-state data and calculated values of state variables. Based on the equivalent logarithmic transformation and SQP algorithm, a solution method for the parameter identification model is proposed. The optimal parameter values are obtained through the calculation. Compared with the existing error results in the literature, this approach achieves smaller concentration error value. References | Related Articles | Metrics

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Modeling the potential impact of probiotics in the treatment of prostate cancer KANG Xia-xia, HE Yan 2024, 50 (4):  159-167.  Abstract ( 39 )   PDF (2392KB) ( 26 )   Save According to the interaction mechanism between probiotics and prostate cancer cells, a three-dimensional stochastic cancer dynamic model composed of probiotics, androgen-dependent prostate cancer cells and androgen-independent prostate cancer cells was constructed. The sufficient conditions for the persistence and extinction of prostate cancer cells were obtained by constructing an appropriate V function. The therapeutic effect of probiotic-assisted androgen deprivation therapy against prostate cancer was simulated and predicted. The study found that probiotics’ inhibitory effect on prostate cancer cells and noise intensity played an important role in the persistence and extinction of prostate cancer cells. In particular, further studies have shown that enhancing noise or improving the inhibitory effect of beneficial bacteria on androgen-independent cancer cells can not only effectively eradicate cancer cells but also effectively prevent the occurrence of drug resistance. References | Related Articles | Metrics

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The existence of multiple solutions for a Kirchhoff-type equation with indefinite CHEN Lin-song, HU Tian-qun, ZHOU Jian 2024, 50 (4):  168-172.  Abstract ( 43 )   PDF (539KB) ( 39 )   Save A Kirchhoff-type equation in RN with the indefinite potential is studied here. The existence of multiple solutions is obtained for the equation via Morse theory and variational methods. References | Related Articles | Metrics