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28 December 2023, Volume 49 Issue 6 Previous Issue    Next Issue

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Materials Science and Engineering

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Organizational structure and mechanical properties of Al2O3 interfacially modified unidirectional fiber C/C composites JIA Jian-gang, NIU Chao, ZHANG Zhen, FU Fang-xing, PAN Zi-kang 2023, 49 (6):  1-8.  Abstract ( 164 )   PDF (5784KB) ( 143 )   Save In order to alleviate the brittleness of C/C composites, the unidirectional carbon fiber preform was treated with Boehm sol, and the Al2O3 coating was prepared on the fiber surface. The preform was densified by self-made thermal gradient chemical vapor infiltration (TG-CVI) deposition equipment to obtain a dense C/C composite. The bonding strength of the interface and the graphitization degree of the matrix carbon were further adjusted by high-temperature heat treatment.The density of the composite material was tested by drainage method, while tensile properties were assessed with the universal material testing machine. The sample was treated with the visualization of graphene texture (VGT). The microstructure, interfacial, and cross-sectional morphologies of the composite were studied using polarizing microscope (PLM), scanning electron microscope (SEM), and X-ray diffraction (XRD) to analyze phase composition. The results showed that the C/C composites coated with Al2O3 coating transform into rough layer (RL) texture in the late deposition stage. After high-temperature heat treatment, the graphitization degree of the carbon matrixis increased. As a result of this, the fracture mechanism of the C/C compositeis significantly changed. The elongation is improved from the initial brittle fracture of the composite to the quasi-ductility. The peak stress of the Cf(Al2O3)/C-3 sample reached 77.3 MPa, and the elongation reached 15%. References | Related Articles | Metrics

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Corrosion deterioration behavior of reinforced concrete based on Weibull distribution in salt spray environment WANG Yan-peng, WANG Zi-jian, WANG Li-juan, LIU Ji-lin, FENG Qiong, ZHANG Yun-sheng 2023, 49 (6):  9-15.  Abstract ( 113 )   PDF (3741KB) ( 148 )   Save In view of the serious issue of reinforced concrete deterioration under the atmospheric environment of the western region, the corrosion characteristics of reinforced concrete under salt spray dry-wet accelerating corrosion experiment were investigated by electrochemical and concrete damage degree tests. Based on Weibull distribution function, the deterioration model of reinforced concrete in salt spray environment was established, and the competitive failure analysis was carried out. The results showed that under the environment of salt spray dry-wet cycles, both the protective layer of reinforced concrete and the internal reinforcement exhibit a trend of initial strengtheningand then following subsequent deterioration in corrosion resistance. Weibull distribution function can effectively describe the deterioration process of reinforced concrete under salt spray dry-wet environment. In the early stage of salt spray dry-wet cycles, the damage degree of concrete is more sensitive than the corrosion current density, while in the later stage, the corrosion current density becomes the dominant factor for the deterioration of reinforced concrete. References | Related Articles | Metrics

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Grey entropy analysis of the fineness of granite powder and mortar strength ZHANG Yun-sheng, HU Xiang-nan, XUE Cui-zhen 2023, 49 (6):  16-21.  Abstract ( 94 )   PDF (2109KB) ( 110 )   Save In order to improvethe utilization rate of mechanism sand powder,based on the analysis of the mechanism of granite sand powder (hereinafter referred to as stone), the influence of fineness and dosage of particle characteristics on mortar strength, the significant impact of stone powder fineness on mortar strength was investigated employing the grey relational entropy analysis method. Additionally, the effects of limestone on the micro-properties of mortar were analyzed using scanning electron microscopy (SEM) analysis method. The results showed that the strength of mortar increases first and then decreases with the increase of stone powder content. With the increase of grinding time of stone powder, the specific surface area of stone powder is increased,which is characterized by an increase in particle content with a size of less than 10 μm and a decrease in particle content with a size of greater than 40 μm. The analysis of ash entropy results showed that the particle parameters and particle distribution of stone powder have a certain influence on mortar strength, among which the specific surface area has the most significant effect on mortar strength, which is a significant factor affecting the activity of stone powder. The stone powder in the range of 10~40 μm prove to be the most beneficial for improving the strength of mortar. The results of microscopic analysis showed that the appropriate amount and fineness of stone powder can improve the quantity and morphology of hydration products in the cementitious system, thereby affecting the macroscopic mechanical properties of mortar. References | Related Articles | Metrics

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Investigation on oxidation of corn starch and its grafting for the preparation of loess dust suppressants XIAO Jun, GAO Hui, ZHANG Zhi-min, SONG Yong-gang, LI Kang 2023, 49 (6):  22-27.  Abstract ( 101 )   PDF (1542KB) ( 105 )   Save Using corn starch as raw material, the catalytic oxidation wet method was used to study the catalytic oxidation effect of pH, hydrogen peroxide, copper sulfate, temperature and time on corn starch by designing orthogonal experiments, and activated oxidized starch was prepared, the green environmentally loess curing dust suppressant was prepared by using acrylic acid grafting modification of oxidized starch. The results showed thatpart of the hydroxyl group of the corn starch is oxidized into carboxyl group, and the carboxyl content of the oxidized arrowhead starch is 0.371%,at pH=9, 8 mL of H2O2, the CuSO4in 0.04% of the dry basis,and 2 hours of the reaction time at 65 ℃,which showgood oxidation effect is achieved. The results of scanning electron microscope analysis showed that the oxidation reaction is mainly occurred on the surface of starch. Using the starch with the best oxidation degree as the base material, a new green and environmentally dust fixing agent is synthesized bygrafting the acrylic monomer on the oxidized corn starch.And the hardness of the top layer of loess reach 71.4 HA after spraying, which has a very good effect of loess curing and dust suppression. References | Related Articles | Metrics

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Crack propagation in GH4151 alloy during hot deformation LIU Jian-jun, WEI Bao-lin, JIA Zhi, DING Yu-tian 2023, 49 (6):  28-32.  Abstract ( 124 )   PDF (2919KB) ( 153 )   Save GH4151 alloy is a new type of nickel-base superalloy that is difficult to deform and can be used above 800 ℃. Due to the high alloying degree and large grain size of as-cast GH4151, it is easy to crack during hot deformation and can not be deformed such as cogging. The hot deformation behavior of GH4151 alloy at different temperatures and strain rates was investigated by the Gleeble-3500 thermal simulator. Electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM) were used to characterize the typical crack area, and the effects of grain orientation, recrystallization, low energy grain boundary, and solid solution phase on the crack propagation were analyzed. The results showed that the grains with 〈101〉 orientation can effectively hinder crack propagation compared with the grains of 〈001〉 and 〈111〉. The formation of recrystallized grains reduces the stress in the alloy, thereby reducing the crack growth rate. Low-energy grain boundaries have stronger resistance to crack propagation than random grain boundaries, and the greater the number of low-energy grain boundaries at the trifurcate grain boundary, the stronger the resistance effect. The crack propagation is promoted by the formation of a solid solution phase with brittle characteristics. References | Related Articles | Metrics

Mechanical Engineering and Power Engineering

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Numerical simulation and experimental research on fracture toughness of T300/69 laminated considering 90° sub-layup WEI Yao-bing, WANG Xue-xue, JIN Yi-fan, LIU Jian-hui, LANG Shan-shan 2023, 49 (6):  33-40.  Abstract ( 111 )   PDF (4131KB) ( 163 )   Save A modified fracture toughness calculation method is proposed in this research to address the shortcoming that the existing fracture toughness calculation model for composite laminates ignores the effects of 90° sub-layers and fiber debonding on fracture toughness. First, in the study of fracture toughness of orthotropic anisotropic fiber-reinforced composites, an extended finite element method is used to simulate the crack expansion process of T300/69 fiber-reinforced composite laminate with the help of ABAQUS finite element software to analyze the effect of 90° sub-layers on the overall fracture toughness of the laminate. Next, the fracture toughness model considering the effect of fiber debonding combined with energy release rate was established considering the effect of 90° sub-layers. Finally, the fracture toughness of T300/69 composite laminate under different paving methods is studied by compact tensile experiments using displacement-load data to verify the accuracy of the model. The results show that the fracture toughness obtained from the model proposed in this paper exhibits minimal disparities from the experimental results, thereby rending it more representative of the real-world applications. The proposed model holds significant practical implications for practical engineering. References | Related Articles | Metrics

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Study on the optimal allocation of co-production system based on multi-renewable energy LI Jin-ping, NIU Yi-nan, LI Zi-jing, LI Tian-shu, VOJISLAV Novakovic, WANG Chun-long 2023, 49 (6):  41-49.  Abstract ( 85 )   PDF (4054KB) ( 133 )   Save In order to improve the overall performance of co-production system based on multi-renewable energy, a reasonable capacity allocation is very important. For the co-production system based on biomass, solar and air energy, the maximization of primary energy saving rate, annual cost saving rate and carbon dioxide emission reduction rate are selected as the optimization functions, and the capacity of PV/T, internal combustion engine and air source heat pump are selected as decision variables. Using the NSGA-Ⅱ algorithm and weight-TOPSIS, the optimal capacity allocation is solved. Finally, the feasibility of the optimization model is validated through illustrative examples, and the sensitivity of system economic performance to cost parameters is explored. The results show that the optimized scheme exhibits excellent performance in energy, economy and environment, with a primary energy saving rate of 29.07%, an annual cost saving rate of 58.15%, and the carbon dioxide emission reduction rate of 54.30%. Furthermore, the cost parameters of anaerobic fermentation have a substantial influence on the economic performance of the system. References | Related Articles | Metrics

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Parameters analysis and optimization of Ⅲ combined profile variable wall thickness scroll tooth PENG Bin, TAO Yaohui, LIU Huixin 2023, 49 (6):  50-56.  Abstract ( 70 )   PDF (2832KB) ( 100 )   Save In order to study the influence of the profile parameters on the geometric performance of the variable cross-section scroll tooth, mathematical models were established for the profile area, occupancy ratio, and suction volume of III combined profile variable wall thickness scroll tooth, the relationship between the profile parameters and which are obtained. Utilizing algorithm NSGA-Ⅱ, the multi-objective optimization design is carried out with the occupancy ratio and the stroke volume as the optimization objectives, resulting in a Pareto optimal solution set of the relevant profile parameters. Subsequently, a comparative analysis is conducted between the optimized scroll tooth and unoptimized ones in terms of their geometric and mechanical performance.The result show that geometrical performance of the variable wall thickness scroll tooth is improved effectively through optimization of algorithm NSGA-Ⅱ but it is not conducive to enhancing the mechanical performance. The research results can provide valuable insights into the selection of the profile parameters in the design of the Ⅲ combined profile variable wall thickness scroll tooth. References | Related Articles | Metrics

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Investigation on the performance of a dual temperature heat pump with intermediate discharge of refrigerant CHEN Zhao, LI Feng-lei 2023, 49 (6):  57-63.  Abstract ( 78 )   PDF (2739KB) ( 79 )   Save A novel dual-temperature condensation heat pump with the intermediate discharge of refrigerant (DTHP-IDR) is proposed to supply heat at two temperature levels. The system model was set up. in which R1234yf was used as the refrigerant. The results show that as the intermediate exhaust ratio increases, the compressor consumption decreases, and the heating performance coefficient increases. As the evaporation temperature increases, the mass flow rate of the compressor, the compressor consumption, and the heating performance coefficient all increase. As the middle-temperature condensation temperature increases, the compressor consumption increase, while the heating performance coefficient decrease. As the high-temperature condensation temperature increases, the compressor consumption and the heating performance coefficient of DTHP-IDR increase and decrease respectively too. It is found that when the evaporation temperature is 5 ℃, the middle and high-temperature condensation temperatures are 40 ℃ and 65 ℃, respectively. When the exhaust ratio is 28%, the heating performance coefficient of DTHP-IDR is improved by around 11% compared with the traditional single condensing heat pump system. References | Related Articles | Metrics

Chemical Industry and Light Industry

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Study on the characteristics of gas-liquid flow and separation in the interspace of polygonal deflector MA Feng, WU Dan-dan 2023, 49 (6):  64-71.  Abstract ( 69 )   PDF (4712KB) ( 183 )   Save Based on the DPM and Lagrange liquid film model, a gas-liquid flow analysis model is established in the interspace of a polygonal deflector. The accuracy of the model is verified by experimental data. The influence of deflector operating parameters is studied on separation performance. The results show that the separation efficiency will gradually increase to a certain extent with the increase of the inlet flow rate. Therefore, during the operation of gas-liquid separation equipment, the separation efficiency can be improved by appropriately increasing the inlet flow rate. At the same time, the pressure drop will be increased, which will increase the energy consumption of the system. When the droplet size is less than 130 μm, the separation efficiency will slowly decrease with the increase of droplet size. While when the droplet size is greater than 130 μm, the separation efficiency will gradually increase with the increase of droplet size. Therefore, the inlet droplet size under this blade structure can be increased within a reasonable range to improve the separation efficiency. In general, the droplet size has little effect on the pressure drop, which can provide theoretical basis for the operation optimization of gas-liquid separation equipment. References | Related Articles | Metrics

Automation Technique and Computer Technology

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Fault diagnosis for chemical process based on an improved LSTM neural network DU Xian-jun, QIU Xiao-yu 2023, 49 (6):  72-79.  Abstract ( 172 )   PDF (2999KB) ( 109 )   Save According to the characteristics of data nonlinearity, high dimension, and dynamic time sequence in modern chemical processes, traditional methods have low accuracy for fault diagnosis. Therefore, a fault diagnosis method based on improved long short-term memory (LSTM) neural network is designed in this paper. First, the collected fault data were input into a convolutional neural network (CNN) to extract the features and reduce the dimension of the data. Secondly, the processed data was input into the improved LSTM network for deep feature extraction. Finally, the extracted deep feature information was input into the attention mechanism for feature “focusing” to realize feature fusion, and then input into the softmax classifier to realize fault classification. Simulation results on the Tennessee-Eastman (TE) dataset demonstrate that the proposed method is better than recurrent neural network (RNN), gated recurrent unit (GRU), CNN, and deep auto-encoder network (DAEN) in fault classification accuracy and diagnose speed, which has certain advantages in the application of the practical chemical process. References | Related Articles | Metrics

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Random forest imbalanced data classification algorithm based on DBSCAN clustering decomposition and oversampling ZHAO Xiao-qiang, YAO Qing-lei 2023, 49 (6):  80-89.  Abstract ( 101 )   PDF (1827KB) ( 75 )   Save To address the problem that traditional methods are prone to generate a large number of false samples or data loss when classifying imbalanced data, a random forest imbalanced data classification algorithm based on DBSCAN clustering decomposition and oversampling is proposed. First, the density-based DBSCAN clustering decomposition algorithm was applied to the majority class of the imbalanced dataset, which reduces its advantage without data loss. Secondly, the minority class was oversampled by the Borderline-SMOTE algorithm. The number of minority samples was increased to obtain a more balanced dataset, which effectively solved the problem of over-fitting caused by generating too many false samples during over-sampling, and at the same time avoided the problem of data loss caused by under-sampling. Finally, under the premise of the clustering decomposition and oversampling algorithm, random forest achieved better results than SVM, Adaboost, Bagging, and XGBoost. Experimental comparison with other popular algorithms on the KEEL public dataset shows that the proposed algorithm can effectively improve the classification performance of imbalanced data. References | Related Articles | Metrics

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Frequency doubling modulation and power balancing method for two-unit five switch inverter HU Wen-hua, DING Wen-bin, YU Zheng-yan, XING Rui-xin, YU Shu-kun, XIONG Zhi-lei 2023, 49 (6):  90-94.  Abstract ( 59 )   PDF (2100KB) ( 77 )   Save In order to solve the problem of fewer output levels existing in the positive and negative re-laminated H-bridge under the strategy of positive and negative reverse laminated velocity pulse width (POD-PWM) modulation, a new Topology with two-single-level co-level is proposed, as well as an improved POD-PWM double frequency modulation strategy. In order to eliminate the imbalance problem of power between the two units, the method of switching two-unit switch tube driving signals is adopted using a 1/2 output voltage cycle based on the improved POD-PWM frequency doubling modulation strategy. From the simulation and experimental study, the accuracy and practicality of the above theoretical analysis are proven. References | Related Articles | Metrics

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Optimal configuration of voltage unbalance control equipment in distribution network HE Feng, WEI Guang-ming, YIN Qiao-rong, NI Yuan-hong, WANG Jie 2023, 49 (6):  95-99.  Abstract ( 84 )   PDF (1271KB) ( 189 )   Save Aiming at the problem of voltage unbalance caused by high proportion of photovoltaic power generation system in distribution network, an optimal configuration method combining voltage sensitivity matrix method and Gamultiobj function genetic algorithm was proposed. Firstly, the voltage sensitivity matrix method with road association matrix T is used to analyze the voltage weak nodes in the system and determine the governing node set. Then the multi-objective optimization model of voltage unbalance control equipment is constructed, and the weight and penalty factor are introduced to improve the model into dynamic model to ensure the accuracy of solution set. Finally, Niche technology was used to improve the environmental fitness of the sub-population of Gamultiobj function genetic algorithm, and the optimal configuration scheme considering voltage imbalance degree and economic cost was solved. The feasibility of the proposed method is verified by the simulation of IEEE30 node system. References | Related Articles | Metrics

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A generation method of malicious domain name training data based on generating adversarial network LIU Wei-shan, MA Xu-qi, WANG Hang, WU Zi-yan 2023, 49 (6):  100-106.  Abstract ( 109 )   PDF (2595KB) ( 107 )   Save Domain generation algorithm(DGA) is widely used by cyber attackers to generate a large number of random domain names to evade detection at present. While the existing DGA domain name detection can not effectively detect unknown malicious domains, because these models are all trained and constructed on publicly available datasets. In this paper, an autoencoder(AE) is first trained using real domain names, and then it is combined with the generative adversarial network(GAN) to construct a new DGA domain name generating model. Experiment results show that the sequences generated by this model are similar to the Alexa domain names in terms of length and character distribution, and it also can effectively reduce the performance of the DGA domain name classifier based on a long short-term memory (LSTM) network. These generated sequences enrich the malicious domain name dataset, which can significantly improve the performance of existing DGA domain name detectors with further utilization. References | Related Articles | Metrics

Architectural Sciences

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Experimental study on the influence of nano-scale metakaolin on flexural and splitting tensile strength of recycled aggregate concrete YAN Jie, LUO Yan, BAI Yong-qing, XING Guo-bin, XIE Jun 2023, 49 (6):  107-113.  Abstract ( 103 )   PDF (3630KB) ( 56 )   Save To investigate the influence of nano-metakaolin on the mechanical properties of recycled concrete, the experiment used the dosage of nano-metakaolin (NMK) (3%, 5%, 7%) and the replacement rate of recycled aggregate (30%, 50%, 100%) as variables to prepare nano-recycled concrete and splitting tensile and flexural strength tests were conducted. By combining optical microscopy, scanning electron microscopy (SEM), specific surface area and pore size analyzer, the microstructure and pore size distribution characteristics of the failure surface and interface transition zone (ITZ) were studied, revealing the influence of NMK on the splitting tensile and flexural strength of recycled concrete. The experimental results show that the addition of NMK has an improvement effect on the splitting tensile and flexural strength of recycled concrete with different substitution rates. The analysis of specific surface area and pore size shows that NMK filled recycled concrete has some large and mesoporous pores inside, which can reduce the total pore volume and specific surface area, refine the pore structure of recycled concrete, and improve the structural density. The microstructure analysis under the microscope shows that with the increase of NMK content, the C—S—H gel produced by hydration reaction is gradually increasing, the pores and cracks in the internal structure are reduced, and the internal microstructure of recycled concrete is more dense. References | Related Articles | Metrics

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A new method for determining critical slip surface of cohesive soil slope ZHANG Ai-qing, LI Jin-yun, SHAN Wei, GUO Ying 2023, 49 (6):  114-118.  Abstract ( 83 )   PDF (1119KB) ( 121 )   Save In order to propose a method for determining the critical slip surface of cohesive soil slope with strong operability, based on the principle of simple penetration test and the research results of standard penetration times and foundation bearing capacity, the relationship between the number of simple penetrations and bearing capacity of the slope is established. Combined with a road slope example, measuring points was arranged and the number of simple penetrations was measured on the slope. The bearing capacity of the slope at different depths was calculated and the curve of slope bearing capacity with depth was drawn, in which the sudden change of the bearing capacity of the slope was searched for and its curve was obtained to determine the critical slip surface of the slope. The results of the paper are compared with the results by the finite element method and theoretical method to verify the feasibility and rationality of the simple penetration method. The results show that the simple penetration method is suitable for the determination of the critical slip surface of cohesive soil slope, and it can quickly and accurately determine the critical slip surface of clayey soil slopes, which provides a new method for the stability analysis of cohesive soil slopes. References | Related Articles | Metrics

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Optimal design of gradation of high-volume RAP plant-mixed hot-recycled asphalt mixture based on response surface methodology ZHAI Xiao-cheng, DING Pan, LEI Yu-tao, ZANG Chao-jie, ZHANG Fu-kui, LI Ping 2023, 49 (6):  119-128.  Abstract ( 76 )   PDF (5524KB) ( 119 )   Save In order to avoid insufficient selection of the optimal gradation curve using empirical methods when optimizing the gradation design of asphalt mixtures, the response surface method was used to optimize the gradation design of RAP plant mixed hot recycled asphalt mixtures with a large content (30%) of AC-20 gradation type. The optimal design result can be obtained when the 19 mm sieve pass rate of the aggregate was 97.2%, the 4.75 mm sieve pass rate was 39.3%, the 0.075mm sieve pass rate was 6.0%, and the oil stone ratio was 4.48%. Under optimal conditions, the predicted values of the model were void rate of 4.00%, void ratio of 13.17%, saturation of 70%, and stability of 11.75kN. The experiment shows that the relative error between the measured values and the predicted values of the model is small (both not more than 3%), indicating that the established second-order model has good fitting results. The response surface method can effectively predict the performance of asphalt mixture mix design and provide optimization results for the grading of 40% to 70% RAP content. References | Related Articles | Metrics

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Behavior of recycled aggregate concrete filled stainless steel tube (RA-CFSST) stub columns under axial compression MA Hai-bing, HU Yong-sheng, ZHANG Wen-hao, ZHAO Hui, SHEN Ling-hua 2023, 49 (6):  129-137.  Abstract ( 59 )   PDF (6581KB) ( 29 )   Save Recycled aggregate concrete filled stainless steel tube (RA-CFSST) have gained significant attention for their potential to enhance the mechanical behaviour of recycled aggregate concrete (RAC), especially in applications like bridge piers and marine structures. In this paper, the ABAQUS finite element (FE) software was used to analyze the behavior of RA-CFSSTs under axial compression. The stress states of stainless steel and core RAC were investigated based on reliable FE models. Stress distribution of core RAC and contact pressure between steel tube and concrete were analyzed. Afterwards, a parametric analysis was performed to evaluate the influences of concrete strength, coarse recycled aggregate replacement ratio, types of stainless steel and steel ratio on the axial compression response. Furthermore, a comparative assessment is made with existing design provisions for the CFSTs and RAC-FSTs, both domestically and internationally, based on experimental results and parametric analyses.The results show that the circumferential stress of steel tube and vertical stress of core RAC continuously increased under axial compression, indicating an obvious confinement effect. The ultimate load-carrying capacity of RA-CFSSTs is found to be primarily influenced by material strength and steel content, while the effect of recycled coarse aggregates was minor. References | Related Articles | Metrics

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Discussion on the factors influencing interlayer anti-shear fatigue in asphalt mixture based on gray entropy theory ZHENG Wan-peng, NIAN Teng-fei, WANG Guo-wei, WEI Zhi-qiang, LIU Zong-cheng, LIU Wen-ke 2023, 49 (6):  138-144.  Abstract ( 92 )   PDF (4329KB) ( 58 )   Save To investigate the degree of correlation between the fatigue life of interlayer shear in asphalt pavement and the contributing factors, a shear fatigue test was assembled. A conprehensive series of interlayer shear fatigue tests of asphalt mixtures with different composite structure layers were carried out on the UTM-100 asphalt pavement universal test material machine. The shear fatigue test encompass different composite structural layer types, different viscous layer oil types, different loading frequencies, different stress levels and temperature effects. The degree of correlation between these influencing factors and the fatigue shear life are employed based on the grey entropy theory. The results show that the SBS-modified asphalt binder material exhibits markedly superior interlayer shear fatigue performance compared to modified emulsified asphalt binder material, with the latter outperforming base asphalt binder material. When the stress level was increased from 0.3 to 0.4, the interlayer shear fatigue life of the asphalt mixtures was all reduced by approximately 60% to 65%, and the interlayer shear fatigue life of asphalt mixtures was reduced by approximately 45% to 65% when the temperature was increased from 20°C to 30°C. The degree of relationship between the interlayer shear fatigue performance of asphalt mixture and its influencing factors ranks as follows: loading frequency > stress level > temperature > type of viscous layer oil. References | Related Articles | Metrics

Scientific

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Adaptive stability control for a class of nonlinear multi-parameters uncertain cascade systems HE Qiu-jin, ZHANG Jian 2023, 49 (6):  145-153.  Abstract ( 102 )   PDF (1950KB) ( 115 )   Save This paper studies the adaptive state feedback stability control problem for a class of nonlinear multi-parameters uncertain cascade systems that suffer the multi-parametric uncertainty represented by unknown vectors, actuator failure, and full-state constrained conditions. By constructing appropriate barrier Lyapunov function and employing a combination of Backstepping iterative design methodology and adaptive techniques based on projection operators, an adaptive state feedback control design scheme is successfully constructed. The designed controller is proven to guarantee that all the closed-loop system states are bounded, and the original system states not only meet the specified constrained conditions but also asymptotically converge to the origin. The correctness and validity of the obtained theory results are verified by two simulation examples. References | Related Articles | Metrics

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Semi-tensor product method for solving least square Toeplitz solutions of quaternion matrix equation YAN Li-mei, ZHAO Lin-lin, DING Wen-xu, LI Ying, FAN Hong-biao 2023, 49 (6):  154-159.  Abstract ( 87 )   PDF (651KB) ( 92 )   Save Least square Toeplitz solutions and Hermitian Toeplitz solutions of the quaternion matrix equation $\sum_{i=1}^{k} \boldsymbol{A}_{i} \boldsymbol{X}_{i} \boldsymbol{B}_{i}=\boldsymbol{C}$ are studied. Utilizing real vector representation of the quaternion matrix and semi-sensor product theory, the quaternion matrix equation is transformed into its equivalent real matrix equation. Considering the structural characteristics of the Toeplitz matrix and Hermitian Toeplitz matrix, independent elements of the solution matrix are extracted to reconstruct a new solution vector, thus the computational complexity of the problem is reduced. The existing conditions of Toeplitz solutions and Hermitian Toeplitz solutions of the equation are obtained, and the general solutions of the equation are given. Finally, a numerical example is given to demonstrate the precision degree and effectiveness of the algorithm. References | Related Articles | Metrics

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The self-adjointness and dependence of eigenvalues of third-order differential operator with eigenparameters in the boundary conditions LIN Qiu-hong, QIAN Zhi-xiang 2023, 49 (6):  160-168.  Abstract ( 80 )   PDF (534KB) ( 92 )   Save This paper deals with the self-adjointness and the dependence of eigenvalues of a class of third-order differential operators with transmission conditions and two boundary conditions containingeigenparameters. By defining linear operator in a new Hilbert space, the problem is transformed into the study of the corresponding linear operator. Using the operator theory, the self-adjointness of the operator is proved, and subsequently the continuity of eigenvalues is discussed. In particular, the differentiability of eigenvalues with respect to the related parameters is examined, and the corresponding differential expressions are derived. References | Related Articles | Metrics

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Generalized Rickart modules WANG Yong-duo, REN Yu-fang 2023, 49 (6):  169-172.  Abstract ( 95 )   PDF (438KB) ( 97 )   Save The concept of generalized Rickart modules is introduced in this paper. Then the relationships between generalized Rickart modules, Rickart modules, and GSIP modules are studied. Finally, a new characterization of precisely semisimple artinian rings and V-rings is given. References | Related Articles | Metrics