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28 February 2025, Volume 51 Issue 1 Previous Issue    Next Issue

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Materials Science and Engineering

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Effect of fiber laser line energy on microstructure and properties of in-situ synthesized nitriding layer of Ti6Al4V alloy ZHANG Peng-lin, WANG Jia-qi, YU Qi-peng 2025, 51 (1):  1-10.  Abstract ( 297 )   PDF (11045KB) ( 123 )   Save Nitriding layer was in-situ synthesized on the surface of Ti6Al4V alloy by fibre fiber laser in a pure nitrogen atmosphere with different laser line energy. The microstructure and phase composition of the nitriding layers were analyzed. And the effects of line energy on the mechanical properties, wear properties, and corrosion resistance of the nitrided layer were tested. The results showed thatthere is no crack on the surface of the nitrided layerwhen the line energy is 128~180 J/mm, and the main phase is TiN phase, a small amount of α′-Ti phase and TiN0.3 phase. The nitrided layerhas the highest average hardness of 827.1 HV0.3 at a line energy of 180 J/mm.The wear rate is 11.6%~59.8 % lower than that of the substrate. In 3.5 wt.% NaCl solution, the corrosion current density of the nitrided layer prepared at the line energy of 128~200 J/mm is lower than that of the substrate,the corrosiona potential is positively shifted by 0.012~0.082 V, and the polarization resistance is increased by 1.6~3.1 times. References | Related Articles | Metrics

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Effect of thermal cycle on microstructure and mechanical properties of the austenitic heat resistant steel HE Yang, ZHAI Ya-zhong, ZHAO Ji-qing, CHE Hong-yan, LI Ji-guang 2025, 51 (1):  11-18.  Abstract ( 290 )   PDF (8705KB) ( 67 )   Save Austenitic heat resistant steels are widely used in thermal power, nuclear power, aerospace, and other fields owing to their excellent performance at high temperatures. Fine grain size and uniform distributed carbides within the matrix are important reasons for austenitic steels with excellent performance. The microstructure of austenitic steel would experience degradation under extreme working conditions accompanied by thermal cycles. To clarify the effect of microstructure evolution on mechanical properties during the thermal cycle process, three sets of thermal cycles were carried out on an austenitic heat resistant steel 0Cr25Ni13Si2MoN on the condition of delivery. Optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to analyze the microstructure of the materials that experienced thermal cycles after different times. Also, impact toughness tests were carried out, respectively. The results showed that there exists a relationship between the microstructure evolution and time during the thermal cycles, recovery and recrystallization happen to the steel accompanied with M23C6 precipitated around grain boundaries during the first thermal cycle, which decreased the impact toughness, and the density of annealing twins is increased during the next two thermal cycles, however, the carbides is increased and coarsened,which increasesthe impact toughness. References | Related Articles | Metrics

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Effect of annealing on the micro-interface and properties of interstitial-free steel LUO Xiao-yang, ZHAO Xiao-long, WANG Zheng-zhong, WANG Sheng-dong, JIA Zhi 2025, 51 (1):  19-24.  Abstract ( 233 )   PDF (5858KB) ( 67 )   Save The effects of heating rate and annealing temperature on the microstructure and mechanical properties of interstifial-free steel were studied, and the synergistic mechanism of heat treatment parameters on the mechanical properties was revealed. The results showed that with the decrease of heating rate and the increase of annealing temperature, the aspect ratio of the grains decreases and the grains tend to be equiaxed. At a low heating rate, the annealing temperature has a greater effect on the grains. At the same time, the intensity of α-fiber texture decreases with the increase of annealing temperature, while gradually shifts to γ-fiber texture, indicating the formation of recrystallization texture. Tensile tests at room temperature showed that the fracture surfaces are honeycomb-like and belong to typical plastic fractures. With the increase of temperature, the elongation increases, the uniform deformation ability of the material increases, and the drawing ability increases. When the heating rate and annealing temperature are 0.8 ℃/min and 800 ℃, respectively, the minimum aspect ratio is 1.58, the maximum elongation is 40%. References | Related Articles | Metrics

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Effect of heteropolyacid treatment on the electrochemical properties of La-Y-Ni system A2B7-type hydrogen storage alloy performance WANG Cheng-jun, LEI Ming, SHEN Bing-jin, ZHANG Qian-kun, LUO Yong-chun 2025, 51 (1):  25-33.  Abstract ( 150 )   PDF (7982KB) ( 18 )   Save The annealed state A2B7 type La0.33Y0.67Ni3.23Mn0.17Al0.1 hydrogen storage alloy was prepared,and the annealed alloy was impregnated with phosphotungstic acid (H3PW12O40), (phosphotungstic acid (TPA)) aqueous solution. The effects of TPA treatment on the organization, surface morphology, composition , and the electrochemical properties of the alloy were investigated. The results showed that corrosive pits or micropores are formed on the surface of the TPA-treated alloy, and a Ni-rich layer containing tungstate ions with high oxidation valence is formed on the surface of the alloy. The TPA treatment can significantly improve the electrochemical performance of the alloy electrode. The exchange current density I0 of the alloy electrode is the largest when the concentration of TPA is 0.1 mol/L. At this time, the alloy electrode has the largest 1C discharge capacity (364 mAh/g), and its capacity retention rate S100 and high-current discharge performance HRD900 are 93.23% and 81.92%, respectively, which are significantly better than those of the untreated alloy electrode with S100(88.12%) and HRD900(76.05%). The electron transfer impedance at the interface between the electrode surface and the electrolyte solution before and after the TPA treatment is a controlling step affecting the electrode's high-magnification discharge electrodynamic performance. References | Related Articles | Metrics

Mechanical Engineering and Power Engineering

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Influence of the radial position error of plunger hole on overturning moment of cylinder block WANG Jian-sen, HUANG Wei, LI Wen-xuan, LEI Zhen-yu, TIAN Shi-rong 2025, 51 (1):  34-44.  Abstract ( 216 )   PDF (3071KB) ( 62 )   Save Taking a certain type of high-speed swash plate axial piston pump as the research object, a model for cylinder overturning moment that incorporates the inertia force caused by the mass of the piston-slipper assembly and the oil within the piston bore, the central spring force, the oil pressure at the bottom of the plunger, and the supporting force of the valve plate oil film were established. Based on the cylinder overturning moment model under the oil film support force, the random error of the radial distribution position of the plunger hole at the rated operating point and the size and variation law of the additional overturning moment of the cylinder under the definite error are calculated and analyzed. The results show that, within the permissible radial position error of ± 0.1 mm, compared with the ideal situation, the maximum moment fluctuation about the x-axis due to inertial forces is 1.16% when the random error is within ±0.1 mm, while the maximum moment fluctuation about both the x-and y-axes due to the supporting reaction force is 0.64%. For a deterministic error of ±0.1 mm, the additional overturning moments around the x and y axes caused by the inertial force is constant, whereas the maximum moment pulsation around caused by the support reaction force is0.05% about the x-axis and 0.45% about the y-axis. References | Related Articles | Metrics

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Fault diagnosis of rolling bearing based on CEEMDAN combined with improved one-dimensional multi-scale convolutional neural network MA Ning, ZHAO Rong-zhen, ZHENG Yu-qiao 2025, 51 (1):  45-54.  Abstract ( 306 )   PDF (3585KB) ( 224 )   Save To solve the weak feature extraction of the fault signals in rolling bearing and the low fault identification accuracy relying on expert's experience, a fault Identification method combining complete ensemble empirical mode decomposition with adaptive denoise and improved one-dimensional convolutional neural network was proposed. First, the complete ensemble empirical mode decomposition is used to denoise the bearing signal, followed by signal reconstruction using Person correlation coefficient method on the obtained intrinsic mode functions (IMFs). Next, the first layer of the network adopts a method of combining large-scale kernels and atrous convolutions, the pyramid scene parsing network is introduced and leading to a proposed one-dimensional multi-scale convolutional network for extracting the fault features and the scale of convolution kernel is optimized by PSO algorithm. Finally, the multi-scale feature information is integrated to complete the network learning. And it is input into the Softmax classifier to achieve the fault category. The method is verified by the bearing data set of Western Reserve University and the rolling bearing faults data collected at the simulating faults on HZXT-DS-001 rig. The results show that to compare with the traditional method, the method proposed in this paper has good diagnosis results. References | Related Articles | Metrics

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Study of unsteady pressure pulsation in multistage-pump as turbine impeller and guide vane MIAO Sen-chun, TIAN Wang-long 2025, 51 (1):  55-65.  Abstract ( 177 )   PDF (12882KB) ( 35 )   Save During the operation process of a multistage-pump as turbine, the pressure pulsation is one of the key factors affecting the stability of the unit. In order to investigate the regularity of pressure pulsation in this turbine, in this paper, the turbulence model of RNG k-ε is selected to carry out the unsteady numerical calculation. Both the time domain and frequency domain of pressure pulsation are analyzed by the data of pressure pulsation got from the monitoring points distributed in the various each-stages flow components. The results exhibited that the main frequency of pressure pulsation is mainly related to the rotation frequency of the impeller. Upon the optimal operation condition, the rotor-stator interaction between the impeller and the positive guide vanes is considered as the main reason for the pressure pulsation in the impeller. It is the combination effect of both the phenomenon of unstable flow in the impeller and the rotor-stator interaction between the impeller and the positive guide vanes on the increase of pressure pulsation at the monitoring points in the guide impeller under the other flow conditions. Additionally, the main frequency of the positive guide vanes at all levels is closely related to the blade frequency of the impeller, as well as the main frequency of the positive guide vanes is consistent with that of the impeller. The closer the flow passage along the positive guide vane is to the impeller, the greater the pressure pulsation is. Finally, the pressure pulsation in the anti-guide vanes presents a relatively disordered state, showing no obvious change rule. References | Related Articles | Metrics

Chemical Industry and Light Industry

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An efficient protocol for the synthesis of 2,3,5-trisubstituted imidazole derivatives YANG Zheng, CONG Xing-shun, CHEN Yi-wu, ZHANG Gang, XIE Heng-shen 2025, 51 (1):  66-71.  Abstract ( 241 )   PDF (2106KB) ( 110 )   Save By using arylglyoxal monohydrate, aromatic amidine, and acetic anhydride as starting materials, a series of 2,3,5-trisubstituted imidazole derivatives were synthesized via intramolecular cyclization/intermolecular electrophilic addition reaction in acetic acid solvent at 80 ℃. The optimized yields ranged from 63% to 82%. The structures of all products were confirmed by 1H NMR, IR, and HRMS.Additionally, the structure of compound 4c was also confirmed by X-ray single crystal diffraction. References | Related Articles | Metrics

Automation Technique and Computer Technology

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Multi-uncertain rolling optimization scheduling based on information gap decision theory ZHANG Ming-guang, GAO Yan-xia, ZHANG Fei-xiang, WANG Hai-bin 2025, 51 (1):  72-82.  Abstract ( 188 )   PDF (3789KB) ( 247 )   Save Focusing on the uncertainty problems existing in the operation of theregional integrated energy system (RIES), a bi-level robust optimal scheduling model of RIES is constructed by means of the rolling optimization scheduling method and information gap decision theory (IGDT) to translate it into operational economics. The upper layer of the model solves the uncertainty of the system, while the lower layer quantifies these uncertainties through the model revenue base value to ensure that the model operation income is not lower than the expectation, thereby realizing the dynamic scheduling. By adjusting the level factor of the model, different scheduling schemes can be obtained, so as to acquire different scheduling benefit expectations. Decision-makers can choose the appropriate scheduling scheme according to the degree of risk aversion. Finally, the RIES system composed of an improved IEEE33-node distribution network, 19-node heat network, and 20-node natural gas network is tested. The results show that the robust model can improve the system's risk-avoidance by 5% compared to the deterministic model in a given scenario. References | Related Articles | Metrics

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Study on economical optimal allocation of synchronous condenser considering electrical coupling and grid reactive power strength CHEN Shang-peng, BAO Guang-qing 2025, 51 (1):  83-91.  Abstract ( 177 )   PDF (3408KB) ( 61 )   Save The weak reactive power support of new energy power generation equipment is often difficult to meet the stable operation requirements of short-circuit faults in the near area of the power grid. Compensation devices such as synchronous condensers are often configured to improve the voltage intensity of the power grid. Aiming at the configuration optimization problem of the synchronous condenser when the new energy power system fails, the electrical distance is incorporated into the conventional voltage evaluation index, and the location index considering the node coupling is proposed. The index is sorted to screen out the proposed access location of the synchronous condenser. Secondly, taking the short circuit ratio and annual value of new energy multi-station as the constant capacity index, the scheme of minimum configuration cost when meeting the reactive power intensity of the power grid is selected as the optimal configuration scheme of the condenser. Finally, a simulation case is established. The analysis results show that the synchronous condenser configuration point obtained by this method can significantly improve the economy of the configuration scheme while ensuring the voltage intensity of the power grid when the three-phase short-circuit fault occurs, and the effectiveness of the method is verified. References | Related Articles | Metrics

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Image dehazing algorithm based on sky regionsegmentation and edge optimization ZHAO Xiao-qiang, ZHOU Kang-yi 2025, 51 (1):  92-99.  Abstract ( 216 )   PDF (3137KB) ( 74 )   Save Aiming at the insufficient processing ability of the traditional dark channel prior algorithm for the sky area and the sudden depth of field area, and the degraded problems such as halo and color distortion in the restored image, a dehazing algorithm that combines area segmentation and edge optimization algorithm is proposed in this paper. Firstly, an efficient adaptive threshold segmentation algorithm is proposed to separate the sky and non-sky regions in foggy images, and the global atmospheric light value is solved in the sky area. Secondly, the dark channel and transmittance of the sky area of the foggy image are analyzed to derive the transmittance weight map, and then the transmittance of the sky area is obtained. For the non-sky area. an edge optimization algorithm is proposed to improve the dark channel and suppress the appearance of the halo phenomenon. Then the transmittance is refined by guided filtering, and the image is restored by using the atmospheric scattering model. Finally, tone mapping is performed on the restored image to make it more consistent with the visual characteristics of human eyes. The experimental results show that the proposed algorithm in this paper significantly improves dehazing effectiveness, restores the natural appearance of the sky region, effectively suppresses edge halos, and delivers superior performance in both subjective vision and objective indicators. References | Related Articles | Metrics

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A nonlinear extended target tracking method based on noncentral inverse Wishart distribution CHEN Hui, WANG Qiu-ju, PENG Tian-shu, ZHAO Yong-hong 2025, 51 (1):  100-107.  Abstract ( 183 )   PDF (3257KB) ( 107 )   Save To solve the nonlinear extended target tracking problem, a nonlinear extended target tracking method is proposed under the condition of non-central inverse Wishart distribution. First, a non-central inverse Wishart distribution is used to the iterate algorithm under the framework of Bayesian filtering to avoid information loss caused by moment matching or KL divergence minimization. Then, recognizing the limitation of the traditional random matrix (RM) model, which is applicable only under linear observation conditions, the nonlinear measurement information in polar coordinate is linearized by using the de-correlation unbiased transformation algorithm, which ensures the unbiasedness of measurement transformation and avoids the correlation between the transformed measurement covariance estimation and the measurement noise. Furthermore, an effective algorithm for nonlinear extended target tracking based on non-central inverse Wishart distribution is derived. The effectiveness of the proposed method is verified by the tracking simulation of the elliptic extended target. References | Related Articles | Metrics

Architectural Sciences

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Simulation and experimental research on eddy current-magnetic hybrid device ZHU Qian-kun, JIANG Hao-Wen 2025, 51 (1):  108-115.  Abstract ( 211 )   PDF (5238KB) ( 40 )   Save In order to improve the damping performance of an eddy current tuned mass damper (TMD) while save the material cost a new eddy current-magnetic TMD (EMTMD) is proposed by combining eddy current TMD with a magnetic TMD. The working principle of EMTMD is introduced, followed by its design for a pedestrian bridge model. The eddy current damping coefficient and magnetic force damping coefficient are calculated by the experimental method, and the accuracy of the three-dimensional electromagnetic field finite element simulation, including both steady-state and transient analyses, is verified. Subsequently, the three main parameters affecting the two damping coefficient pairs are analyzed by using the verified finite element analysis method, and their influence law is obtained. The EMTMD is optimized according to its influence law.The optimized EMTMD was installed on the pedestrian bridge model for the vibration control test. The experimental results show that the EMTMD provides effective vibration control for the pedestrian bridge model, with superior damping performance compared to the traditional eddy current TMD. References | Related Articles | Metrics

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The probability density evolution analysis of ground vibration induced by subway with stochastic field is considered ZHENG Zhong-yuan, DU Mu-qing, LIU Xin-yuan 2025, 51 (1):  116-122.  Abstract ( 130 )   PDF (4492KB) ( 38 )   Save Foundation soil is an important medium of vibration wave propagation in subway operation, and the spatial variability of soil properties has an important influence on vibration response. Previous environment vibration research often choose for uncertainty parameters of foundation soil, in this paper, the stochastic field theory is introduced into the dynamic analysis of soil property changes, and the stochastic parameter assignment is carried out on the cross section of foundation soil. Based on the probability density evolution method, the environmental vibration caused by subway train in shield tunnel is studied, and the upper and lower limits of surface vibration and probability density distribution information are obtained. The results show that: The stochastic characteristics of soil have a significant effect on the standard deviation of ground vibration displacement and acceleration. The closer the distance from subway center line is, the less the interference of soil stochastic field is, and the more concentrated the probability density distribution of vibration displacement and acceleration is. The soil stochastic field makes the surface vibration response present normal distribution characteristics. The maximum value of ground vibration response appears in the middle time of subway train. References | Related Articles | Metrics

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Research on horizontal bearing performance of FRP reinforced pipe piles in sandy soil HAN Da-yong, GAO Liang, LI Dong, ZHAO Ying-ai 2025, 51 (1):  123-128.  Abstract ( 226 )   PDF (3330KB) ( 45 )   Save FRP material has the characteristics of light weight, high strength and corrosion resistance. The combination of FRP and concrete to reinforce the pile foundation can not only improve the bearing capacity of the pile foundation, but also improve its durability. In order to clarify the horizontal bearing performance of FRP-reinforced pipe piles in sand, the self-designed bi-directional horizontal pile model test system was used, bi-directional horizontal loads were applied to the FRP-reinforced pipe pile model piles buried in sand, and the horizontal bearing performance of sand and FRP-reinforced pipe pile was studied. Based on the test results, an elasto-plastic model of sand was established, assuming that the foundation reaction coefficient is constant. And based on the deflection differential equation of pile, the analytical solutions of the displacement and bending moment of the FRP-reinforced pipe pile were given. The correctness of the calculation method in this paper was verified by the comparison with the test results, and the influence of the load, the foundation reaction coefficient, and the bending stiffness of the pile on the plastic height was analyzed. The variation laws of bending moment and displacement of FRP-reinforced pipe pile with foundation reaction coefficient and pile bending stiffness were studied. References | Related Articles | Metrics

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Fire resistance of flange plate plate-strengthened beam-column joints considering seismic damage XU Ji-xiang, GAN Xiao-shu, JIANG Wang 2025, 51 (1):  129-137.  Abstract ( 154 )   PDF (7374KB) ( 15 )   Save In order to study the fire resistance performance of the flange plate strengthened beam-column joints with flange-reinforced plate after an earthquake, this paper used the finite element software ANSYS was utilized to establish the computational calculation model, and the calculation results were compared with the existing test results to verify the accuracy and efficacy effectiveness of the calculation model.The pushover method was employedused to simulate the seismic damage under different earthquake levels by introducing damage variables D. The residual stress and deformation caused by earthquake were transferred to the heating process by restart analysis method. The fire resistance, ultimate displacement and failure mechanism of flange beam-column joints with flange flange-strengthened beams under different parameters and damage variables were analyzed. The results showed that the damage variable had a major effect on the fire resistance of flange plate plate-strengthened beam-column joints. With the increase of damage variable D, the critical temperature of each connection was decreased greatly. Increasing the parameter α and γ can enhance the fire resistance of flange plate strengthened beam-column joints. While the increase of the β can impair the fire resistance of flange plate plate-strengthened beam-column joints. References | Related Articles | Metrics

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Research on seismic performance of rubber sand foundation-structure based on viscoelastic boundary XU Gang, WANG Feng-chi, YU Hao-tian, XU Lan 2025, 51 (1):  138-144.  Abstract ( 196 )   PDF (4651KB) ( 84 )   Save By using an equivalent uniform viscoelastic artificial boundary, a finite element analysis of the overall seismic performance of foundations and structures composed of layered soils is carried out. The equivalent consistent viscoelastic boundary is applied to the truncated foundation boundary through the spring-damper function supported in ABAQUS, and the earthquake action is suspended by extracting the equivalent nodes of the foundation in the model and applying different equivalent node forces to them. Results indicate that the rubber sand foundation effectively reduce the displacement of the structure, with a maximum reduction of 22.96%, and the maximum displacement reduction is at the structure height of 22 m, with the maximum displacement angle reduction of 0.1642%. Compared with the original foundation, the acceleration of the rubber sand foundation is significantly lower than that of the original foundation, while the acceleration at the bottom of the structure is higher than that of the original foundation, with the maximum acceleration at the nodes higher than that at other locations. Compared with the original foundation, the internal stress of the structure is reduced in the rubber sand foundation. However, the stress at the bottom of the structure is increased. At the same time, both the normal and the shear stress value at the node are higher than other positions, indicating these locations are more susceptible to failure. References | Related Articles | Metrics

Scientific

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Virtually Baer modules WANG Yong-duo, CHEN Yu-hua 2025, 51 (1):  145-149.  Abstract ( 120 )   PDF (659KB) ( 36 )   Save The concept of the virtually Baer modules is introduced, giving an example to illustrate that virtually Baer modules are a proper generalization of Baer modules. Under certain conditions, the closure of virtually Baer modules to direct summands is given. The relationships between virtually Baer modules and GSIP-modules as well as generalized SSIP-modules are discussed. Subsequently, new descriptions of semisimple artinian rings and right V-rings are derived from these discussions. References | Related Articles | Metrics

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Study on the influence of individual migration on HIV/AIDS transmission dynamics CHENG Wan-ting, LUO Xiao-feng, FENG Shan-shan 2025, 51 (1):  150-157.  Abstract ( 233 )   PDF (1942KB) ( 45 )   Save Focusing on the influence of individual migration on HIV/AIDS transmission dynamics, a patch dynamics model coupled with homosexual transmission, heterosexual transmission, and individual migration is proposed. The basic reproduction number is calculated, and the stability of disease-free equilibrium as well as the existence of endemic equilibrium are proved. Numerical simulations verify the theoretical results and explore the effects of different migration modes on HIV/AIDS transmission. Research shows that the connectivity of the migration network has a significant impact on the speed, peak scale, and final scale of HIV/AIDS spread. Specifically, when the migration network is connected, different migration modes have no influence on the final spread scale of HIV/AIDS. The greater the average degree, the faster the spread of HIV/AIDS, and the larger the peak scale. Moreover, when the average degree is the same, the heterogeneity of the degree promotes the spread of HIV/AIDS. In addition, limiting the migration of people living with HIV can effectively curb the spread of HIV/AIDS. These work provides a theoretical basis for the prevention and control of HIV/AIDS. References | Related Articles | Metrics

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Weighted edge neighbor toughness of graphs LI Meng-xuan, WEI Zong-tian 2025, 51 (1):  158-165.  Abstract ( 115 )   PDF (639KB) ( 19 )   Save The edge neighbor toughness is generalized to the weighted graphs, and the concept of weighted edge neighbor toughness of a graph is proposed. After presenting the weighted edge neighbor toughness of some basic graphs, this paper focuses on the extreme problem of the weighted edge neighbor toughness of certain types of graphs, and designs an algorithm to compute the maximum weighted edge neighbor toughness of the complementary graph of cycles. The results show that the weighted edge neighbor toughness can accurately characterize the invulnerability of some networks. References | Related Articles | Metrics

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Existence of multiple positive solutions for p-Laplacian fractional differential equations with a parameter WU Ke-qing, XU Zi-yu, CAI Xu-jun 2025, 51 (1):  166-172.  Abstract ( 173 )   PDF (822KB) ( 44 )   Save A class of nonlinear fractional differential equations of Riemann-Liouville type with p-Laplacian operator and nonlinear terms containing an integral term is considered. The focus is on analyzing its existence of multiple positive solutions under the boundary conditions including a parameter and fractional integral conditions. The problem is transformed into an integral equation by using the Green function. The main results are derived using the Leggett-Williams fixed point theorem and the generalized Avery-Henderson fixed point theorem in the Banach space. The applicability of the result is illustrated by an example. References | Related Articles | Metrics