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28 December 2022, Volume 48 Issue 6 Previous Issue    Next Issue

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Materials Science and Engineering

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Effect of bond coating pre-oxidation on TGO growth behaviors and high- temperature oxidation resistance of thermal barrier coating AN Guo-sheng, LI Wen-sheng, FENG Li, CHENG Bo, LI Zi-yu, ZHOU Lan 2022, 48 (6):  1-7.  Abstract ( 220 )   PDF (14104KB) ( 71 )   Save A dense Al2O3 layer was prepared at the ceramic/bond coating interface of thermal barrier coatings (TBC) by pre-oxidation technology. Isothermal oxidation tests were carried out at 1 100 ℃ to investigate the mechanism of Al2O3 layer reducing growth rates of thermally grown oxide (TGO) by inhibiting oxygen diffusion. The results showed that the TGO thickness and oxidation weight gain of as-sprayed TBC (A-TBC) and pre-oxidation TBC (P-TBC) increase by increasing the isothermal oxidation time. However, the P-TBC significant reduce oxygen diffusion in the entire oxidation process, and inhibite the TGO rapid growth at the initial stage of oxidation. This is contributed to P-TBC keeping a beneficial TGO structure, decreasing parabolic oxidation rate, and finally improving high-temperature oxidation resistance of TBC. References | Related Articles | Metrics

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Effect of sintering process on properties of transparent alumina ceramics HUANG Guo-wei, LI Ting, SUN Li, DI Zheng-xian, FAN Heng-zhong 2022, 48 (6):  8-15.  Abstract ( 376 )   PDF (15266KB) ( 130 )   Save Using Isobam600AF as dispersant and Isobam104 as adhesive, transparent alumina ceramics were prepared by improved two-step sintering method using gelcasting process and vacuum pressureless sintering technology. The effects of different sintering temperatures and holding time on the grain size, density, optical and mechanical properties of alumina ceramics were investigated. The results showed that the sintering process can control the growth of grain sizes and improve the relative density of ceramics effectively, so as to improve their optical properties and mechanical properties. During the sintering process, when the temperature rise to a certain range, the densification process start, and the densification rate first increase and then decreases with the increase of temperature and holding time. The densification rate reaches the fastest value in the condition of the second sintering step holding at 1 400 ℃ for 3 hours. Therefore, the densification of the green body is a nonlinear process with a maximum densification rate temperature and holding time point. References | Related Articles | Metrics

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HPEI graft modification PAN/GO-PAA electrospun nanocomposite fibrous membranes for adsorption of Au(Ⅲ) LI Xiao-hua, MA Ying-xia, YANG Hai-jun, MENG Wen-li, ZHONG Xiao-mei 2022, 48 (6):  16-27.  Abstract ( 161 )   PDF (10178KB) ( 17 )   Save Using acrylic acid (AA) as monomer and benzoyl peroxide (BPO) as initiator, polyacrylic acid (PAA) was coated on the surface of graphene oxide (GO) by in-situ polymerization to obtain GO-PAA nanocomposites. The GO-PAA nanocomposites were dispersed in polyacrylonitrile (PAN) matrix, and PAN/GO-PAA electrospun nanocomposite fibrous membranes were obtained by electrospinning technology. HPEI-g-PAN/GO-PAA electrospun nanocomposite fibrous membranes were fabricated by grafting hyperbranched polyethyleneimine (HPEI) on the surface of PAN/GO-PAA electrospun nanocomposite fibrous membranes with chemical grafting reaction. The adsorption performance of HPEI-g-PAN/GO-PAA electrospun nanocomposite fibrous membranes for Au(Ⅲ) was studied by batch experiments. The results showed that the maximum adsorption capacity of HPEI-g-PAN/GO-PAA electrospun nanocomposite fibrous membranes for Au(Ⅲ) was 1 808.60 mg·g－1. During the adsorption process, partial Au(Ⅲ) was reduced to flake and irregularly granular Au elemental. HPEI-g-PAN/GO-PAA electrospun nanocomposite fibrous membranes had good adsorption selectivity for Au(Ⅲ) in the coexisting ionic system. References | Related Articles | Metrics

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The S-Scheme ZnO/MoS2 heterostructure preparation and degradation performance of tetracycline hydrochloride HU Huai-sheng, ZHANG Peng-hui 2022, 48 (6):  28-33.  Abstract ( 148 )   PDF (3693KB) ( 215 )   Save The wide range and large dosage of antibiotic drugs led to a large amount of antibiotic wastewater entering water body or remaining in soil environment, which posed a threat to human health. However, the removal effect of antibiotics by traditional processes was not ideal. In this study, S-Scheme ZnO/MoS2 heterojunction composite was prepared by doping MoS2 with ZnO as the substrate, and the purification performance of the material on antibiotic wastewater was explored. The purification effect of ZnO/MoS2 composite material on tetracycline hydrochloride (TC) wastewater with different concentrations was investigated by adjusting the ZnO content, illumination conditions and tetracycline hydrochloride concentration in the composite material. The results showed that the degradation efficiency of 60 mg·L－1 tetracycline wastewater is 88% (pH= 7 105 min) when the catalyst composite ratio of ZnO/MoS2 composite material is 1∶1 under light condition.The study of the mechanism of electron transport and pollutant degradation showed that electrons migrate from ZnO conduction band to MoS2 valence band to form S-scheme heterojunction, which effectively improves the catalytic efficiency and pollutant degradation performance. References | Related Articles | Metrics

Mechanical Engineering and Power Engineering

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Prediction method of low cycle fatigue life based on modified Lv model WEI Yao-bing, CHEN Shu-han, LIU Jian-hui, ZI Rong 2022, 48 (6):  34-39.  Abstract ( 164 )   PDF (4145KB) ( 95 )   Save The influence of average stress on the fatigue damage is different when the mechanical properties of materials are different, so the influence of material mechanical properties on the fatigue life is considered to improve the Lv model. Firstly, the Walker index is modified by using the material mechanical characteristic coefficient, which is then introduced into the Lv model. At the same time, the maximum stress is modified considering the effect of normal strain on the fatigue life. Secondly, the plastic deformation part of Lv model is modified based on the improvement of the plastic part of M-H model. In addition, the sensitivity coefficient is introduced to improve the response degree of materials under the influence of average stress since double Walker index is insensitive to material properties. Finally, the low cycle fatigue test data of four kinds of aviation materials, i.e. TA11, GH909, FGH96, and GH4133, are used to compare and analyze the prediction results of SWT model, M-H model, Lv model, and improved Lv model. The results show that the improved Lv model has better dispersion and greater advantages in prediction accuracy and applicability compared with the other three models. References | Related Articles | Metrics

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Fault identification method combined with disturbance ensemble RBF ZHAO Rong-zhen, ZHAO Nan 2022, 48 (6):  40-45.  Abstract ( 96 )   PDF (1793KB) ( 107 )   Save In order to improve the fault recognition accuracy of rotating machinery, an ensemble RBF fault pattern recognition method combining neural network and ensemble learning method is proposed. First, the extracted rotor fault feature dataset is used to calculate the weights of each feature by ReliefF algorithm, which are arranged in descending order to filter out the series of features with larger weights to form a low-dimensional feature dataset. Secondly, the larger weights are used as the input of the non-relaxation roulette algorithm to perturb the series low-dimensional feature dataset and divided them into training sets and testing sets by disturbing corresponding low-dimensional data datasets. Then, the new training set is perturbed by the self-sampling method in the Bagging algorithm to train the corresponding number of RBF neural networks to further complete the construction of the discrepancy subclassifier. Finally, the test data identification results of each neural network are combined with the relative majority voting method to obtain the fault identification results. The experimental results show that for the fault identification of rotor system, the proposed method has higher identification accuracy and better generalization performance compared to nonensemble RBF neural network and ensemble BP neural network. References | Related Articles | Metrics

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Bearing fault diagnosis based on SIR multistage residual connection dense network ZHAO Xiao-qiang, LUO Wei-lan, LIANG Hao-peng 2022, 48 (6):  46-54.  Abstract ( 94 )   PDF (11190KB) ( 35 )   Save In order to study the performance of extracting feature information from time-varying and weak signals of rolling bearings in rotating machinery under complex working conditions, a bearing fault diagnosis method based on SIR multi-stage residual connection dense network is proposed. Firstly, the SIR module is designed, which extracts more important and richer feature information by giving different weights to the input data feature channels and broadening the width of the network. Secondly, a multi-stage residual connection dense network is designed to adaptively extract the effective features from the bearing vibration signals. Finally, a softmax classifier is constructed to realize fault classification. Compared with other methods, the experimental results show that the proposed method can detect faults more accurately under variable noise, variable load, and variable working conditions, and has more robustness and generalization ability for complex working conditions. References | Related Articles | Metrics

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Analysis of the influence of the position of the impeller inlet on the performance of the self-priming pump CHENG Xiao-rui, LIU Ming-jian, YANG Deng-feng 2022, 48 (6):  55-62.  Abstract ( 140 )   PDF (9600KB) ( 29 )   Save In order to study the effect of the gas-liquid mixing capacity of the self-priming pump impeller on the self-priming performance, based on the original model of the impeller, five model schemes with different positions of the blade inlet edge are designed. The VOF multiphase flow model is used to calculate the three-dimensional constant value of the whole basin with different schemes, and the law of influence on the self-priming performance is studied. For the 350WFB-1200-50 external-mixing non-sealed self-priming pump, the initial conditions are set to include a certain volume of air section in the inlet S-shaped elbow, and a gas content monitoring point is set at the outlet. The results show that for the medium and high specific speed impeller, the position of the rear cover of the inlet edge is swept forward to the outlet, so that the fluid is loaded at the inlet side of the impeller, which can effectively improve the gas-liquid mixing capacity of the impeller and shorten the self-priming of the self-priming pump time. Changing the position of the inlet side within a certain forward sweep angle has little effect on the head and efficiency of the self-priming pump, but when the blade inlet side is swept forward to the outlet position beyond a certain range, the head of the self-priming pump will decrease significantly. When the inlet side of the impeller is swept forward by 10°, the self-priming time under rated conditions is shortened by 25%, and the self-priming performance is significantly improved. References | Related Articles | Metrics

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Effect of sealing fluid flow characteristics on magnetoliquid QIN Xing-yao, LI Wang-xu, LI Zheng-gui, LI Yi-bin, YAN Zhao-qiang 2022, 48 (6):  63-66.  Abstract ( 123 )   PDF (3911KB) ( 192 )   Save When the magnetic liquid is applied to seal the shaft of hydraulic turbine, the sealing speed is low and unstable, and the characteristics of sealing liquid flow field have a great influence on the sealing failure. Based on the numerical calculation method, the flow field characteristics of the magnetic liquid seal are compared and verified by the experiments. The results show that the sealing pressure has little influence on the sealing liquid flow field, while the shaft speed has a great influence on the sealing liquid flow field. The conclusion provides theoretical guidance for the design of magnetic liquid sealing device for hydraulic turbine spindle. References | Related Articles | Metrics

Chemical Industry and Light Industry

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Optimization of Baeyer-Villiger reaction mediated by lipase for preparation of ε-caprolactone using response surface methodology XU Hui, XUE Xiao, LI Kai-yuan, LIU Cui, DENG Ya-shan, ZHANG Yuan-yuan 2022, 48 (6):  67-73.  Abstract ( 151 )   PDF (5069KB) ( 122 )   Save Immobilized T. laibaccii lipase-mediated chemical-enzyme Baeyer-Villiger oxidation method can prepare ε-caprolactone. The experimental design was carried out by response surface method, and the optimal reaction conditions were obtained, which the concentration of cyclohexanone was 1.22 mol/L, the molar ratio of cyclohexanone to urea hydrogen peroxide was 1∶1.3, the reaction temperature was 56.5 ℃, the yield reached 98.06%, and the concentration was as high as 1.2 mol/L. There are three reactions in the reaction system of cyclohexanone and ethyl acetate, which the third reaction is that urea hydrogen peroxide reacts with the intermediate acetic acid under the action of immobilized lipase, and acetic acid generates peracetic acid in situ. The quadratic polynomial model was established with the R2 value of 0.998 8, which can accurately predict the yield of ε-caprolactone. In this model, the effect of initial concentration of cyclohexone, the ratio of cyclohexone to urea hydrogen peroxide and reaction temperature on ε-caprolactone yield are considered. The molar ratio of cyclohexone to urea hydrogen peroxide has a very significant effect on the yield of ε-caprolactone (p<0.000 6). References | Related Articles | Metrics

Automation Technique and Computer Technology

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Event-triggered guaranteed cost control of cyber physical systems under DoS attacks ZHU Chao-Qun, HUANG Peng 2022, 48 (6):  74-80.  Abstract ( 151 )   PDF (3851KB) ( 175 )   Save An event-triggered guaranteed cost control method is proposed for security control problem of cyber-physical systems (CPS) under denial of service(DoS) attacks. Firstly, the effect of DoS attacks is described as a Bernoulli random distribution process with the fixed number of packet losses by considering the characteristic of DoS attacks. Secondly, in order to reduce the network communication burden, the discrete event-triggered communication mechanism is used to transmit the measured information of the sensors.Then, according to Lyapunov stability theory and linear matrix inequality method, the sufficient conditions for system stability under denial of service attack are given, and then a guaranteed cost controller based on event triggering mechanism is designed at a given guaranteed cost level. Finally, the correctness and effectiveness of the proposed control method are verified by a simulation example. References | Related Articles | Metrics

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Study on strategy of electric vehicle charging power allocation based on fair weight MAO Yun-juan, ZHU Yue-yang, LI Heng-jie, ZHOU Yun, XIA Qiang-qiang 2022, 48 (6):  81-87.  Abstract ( 150 )   PDF (3549KB) ( 212 )   Save In order to meet the diverse charging needs of large-scale electric vehicle users, a charging power allocation strategy for electric vehicles based on fair weight is proposed. Firstly, the priority penalty mechanism is added to the M/M/C/N queuing model to preliminarily optimize the user waiting time and charging power. Secondly, aiming at the problem of user satisfaction during charging, a user satisfaction function based on penalty factor is proposed. Finally, using the optimized entropy weight method, on the premise of meeting the needs of users, the charging fairness factor between users is involved in the power distribution in the form of weight to realize the fair distribution of available loads in the area, and the user satisfaction function is used to evaluate the power distribution method. The simulation results show that the adding of the charging mode distribution algorithm and the power distribution strategy based on fair weight can further optimize the waiting time and charging power of the users. The proposed user satisfaction function can also effectively evaluate the user’s attitude towards the charging stations, which is helpful to improve the service of each charging station and further optimize the user experience. References | Related Articles | Metrics

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Chaotic system with multistable and adjustable number of attractors YAN Min-xiu, XIE Jun-hong, ZHANG Shuai 2022, 48 (6):  88-95.  Abstract ( 125 )   PDF (2538KB) ( 185 )   Save In chaotic system, chaotic attractors with multistability and adjustable number have important research potential in secure communication. Therefore, it is meaningful to try to build a chaotic system with multistability and adjustable number. Based on the traditional dissipative chaotic system, a simple model of chaotic system is established. By analyzing the dynamic characteristics of the system, it is verified that different attractors can coexist in the same phase space with different initial conditions, and then the multistability of the system is verified. On this basis, the hyperbolic tangent function is introduced into the system. The coexistence of attractors is generated by expanding the equilibrium point of the system, and the coexistence of attractors with adjustable number is established which is verified by relevant theoretical research and numerical simulation. Finally, the experiments and validation of the simulated circuit based on the model system were carried out, which indicate the possibility of the system implementation. Due to the complexity of the dynamic behavior of the coexistence of multisteady state and attractor, the system has good application potential in the field of secure communication. References | Related Articles | Metrics

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Essential protein identification algorithm based on the combination of network topology and multiple biological information LU Peng-li, CHEN Yun-tian 2022, 48 (6):  96-103.  Abstract ( 200 )   PDF (6182KB) ( 223 )   Save Identification of essential proteins helps to understand the basic needs of cell survival and find new methods for disease treatment. Protein itself carries complex biological characteristics, and it is impossible to accurately judge their criticality only by network topology. In this paper, a new method is proposed to improve the accuracy of identifying essential proteins. Firstly, considering the network topology and the importance of proteins in different sub-cells, an indicator called SNC is proposed. Secondly, SIDC indicatoris defined by using the characteristics of proteins in subcellular and complex information. Finally, based on the network topology and multi-source biological information, a new protein recognition algorithm CTB is proposed. Experiments on YDIP, YMIPS, Krogan data sets using accuracy recall and other evaluation methods show that the method in this paper improves theperformance of identifying key proteins. References | Related Articles | Metrics

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Research on intelligent loading optimization scheme of car ferry CHEN Pu, FANG Jing-fang, LIU Jun, CHEN Jia-wei 2022, 48 (6):  104-109.  Abstract ( 166 )   PDF (2678KB) ( 175 )   Save In order to further improve the loading rate of the ferry, improve the economic benefits of the ferry company, formulate a more scientific and reasonable ferry loading scheme, combined with the original ferry process, the intelligent ferry loading process is designed, and the ferry loading model is established. Based on the two-dimensional packing BL algorithm, a ferry loading algorithm is designed, which can automatically calculate and determine the deck parking position of cars. The best loading scheme is obtained through comparison and iteration. The ferry intelligent loading system is designed to directly output the deck vehicle parking position map, and the intelligent loading is realized. Taking the historical data of G company as an example, the correctness and effectiveness of the mathematical model and algorithm are verified by comparing various ferry intelligent loading schemes. The results show that the loading rate is increased by 7.46% and the revenue is increased by 15.7%, which can effectively improve the loading rate of car ferry and the economic benefit of car ferry company. References | Related Articles | Metrics

Architectural Sciences

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Dynamic stability analysis of pile anchor support structure in deep pits based on displacement gradient method ZHOU Yong, ZHAO Yuan-ji, WANG Zheng-zhen, XIONG Si-zhe 2022, 48 (6):  110-119.  Abstract ( 133 )   PDF (5915KB) ( 124 )   Save The search model of the slip surface and the calculation method of the safety factor are the two important contents to analyze the stability of the pile-anchor support structure of deep foundation pits. In this study, the most dangerous slip surface is searched by the tangential displacement gradient method, and the calculation model of the safety factor is improved based on the limit equilibrium theory. The sliding surface is searched in two steps: searching the direction with the maximum tangential displacement gradient as the tangent direction of the sliding surface; the next point of the sliding surface is determined according to the direction of the maximum tangential displacement gradient. In the calculation of the safety factor, the effect of tensile failure on the anti-sliding moment of the soil is considered through the stress ratio. Finally, the location of the slip surface and the tensile failure area are substituted into the improved safety factor formula to calculate the safety factor of the foundation pit under the corresponding working conditions. Through the analysis of numerical examples, it is found that the tangential displacement gradient has a maximum value in the range of 0° to 90°. The tensile failure zone is concentrated in the shallow soil layer and changes dynamically with the construction process. References | Related Articles | Metrics

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Assessment method of roof greening in Lanzhou icth based on fuzzy comprehensive evaluation LIU Ben-teng, ZHOU Yu-qing, WANG Xue-ping, LIU Qi 2022, 48 (6):  120-126.  Abstract ( 117 )   PDF (1155KB) ( 185 )   Save The purpose of this paper is to explore a scientific and effective evaluation method of roof greening in combination with natural geographical conditions. The roof greening of Lanzhou city was selected as the research object. In this study, the evaluation index system is constructed from the aspects of design rationality, cost input, green benefit, and maintenance quality. The fuzzy comprehensive evaluation method is used to evaluate the roof greening status in Lanzhou. The results demonstrate that Lanzhou City's comprehensive evaluation of roof greening is mostly in the middle and poor level, which has a large space to be improved. The physical and chemical characteristic index of roof greening substrate is lower and the lack of attention to the construction of drainage and aquifer layer is the binding factor affecting the green benefits of roof greening. The insufficient investment in managed funds and general maintenance personnel with low professional ability are the restrictive factors affecting the green benefits of roof greening. In this paper, the evaluation index system and its weight about roof greening based on geographical characteristic are scientific and effective to some extent. These results can provide a reference for urban eco-environmental resource management and planning in arid and semi-arid areas. References | Related Articles | Metrics

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Research on the optimization of the partition wall in the tunnel construction by the sub-excavation method ZHANG Wei, QIAO Xiong, LUO Wei-bin, WANG Yan-wen TIAN Guo-qin, NI Wei-lin, LIU Wen-gao 2022, 48 (6):  127-135.  Abstract ( 128 )   PDF (11660KB) ( 17 )   Save In view of the problems such as slow construction speed and difficult processing of temporary supports existing in the construction of long-span highway tunnels when the sub-excavation method is adopted, based on the tunnel of Qingshuiyi-Fujiayao Highway of G312 Line,the curved middle partition was replaced by the vertical middle partition,andthe numerical difference between these two partition walls was compared and analyzed using MIDAS GTS. Combining the on-site measured data, the numerical simulation results were verified, following the comparative of the deformation and stress effects of the partition walls of the same structure with different material strengths on the construction of large-span tunnels. The results show that: (1) Both kinds of middle partition support can meet the requirement of construction stability, in which the vertical stress of the vertical middle partition wall is increased by 97.16% compared with that of the curved middle partition wall, and the displacement and deformation of the tunnel surrounding rock and the middle partition wall adopting the vertical middle partition wall are smaller than that of the curved middle partition wall; (2) Comparing two different types of vertical middle partition walls, i.e. I18 and I22b, respectively, in the construction of long-span tunnels, it is found that the maximum stress energy generated by the middle partition wall using I22b steel frame can be reduced by 23.09%. References | Related Articles | Metrics

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Influence of foundation pit excavation on the surrounding environment WEI Yun-xia 2022, 48 (6):  136-144.  Abstract ( 312 )   PDF (7843KB) ( 79 )   Save In order to explore the response of the foundation pit and the surrounding environment during the excavation of the foundation pit, taking the actual foundation pit project in the northwest as the background, the corresponding model was established by Plaxis 3D software, and the deformation of the foundation pit and its surrounding environment and the change of the force on the anchor rod of the retaining structure during the excavation of the foundation pit are analyzed. The results show that the soil deformation caused by the excavation of the foundation pit is a three-dimensional problem. The deformation of the soil body in the profile is affected by the yin and yang angles of the foundation pit. The extent of this effect is related to the distance between the profile and the internal and external corners of the foundation pit.In the retaining structure of foundation pit, the anchoring effect of anchor bolt is about 30% better than that of soil nail, and the supporting effect of pile anchor is about 20% better than that of composite soil nail wall. The lower row of bolts bears more active earth pressure than the upper row of bolts, and the axial force in the free section is greater than the upper row of bolts. The road near the composite soil nailing wall support section is affected by the excavation of foundation pit, and its inclination direction changes from the initial inclination towards the outside of the pit to the inside of the pit. The deformation of existing buildings near the pile anchor support section is within the allowable range of relevant specifications, and the surrounding existing buildings are in a safe state. References | Related Articles | Metrics

Scientific

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Generalized D4 modules WANG Yong-duo, XU Peng 2022, 48 (6):  145-148.  Abstract ( 87 )   PDF (1069KB) ( 90 )   Save As a proper generalization of D4 modules, the concept of generalized D4 modules is introduced in this paper. Some equivalent conditions of generalized D4 modules are given by studing the basic proerties of such modules. Furthermore, the concept of pseudo D4 modules is introduced. and it is shown that a ring R is semisimple if and only if each R-module is a pseudo D4 module. References | Related Articles | Metrics

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Solving partial differential equation with complex geometries based on deep neural network GUO Xiao-bin, YUAN Dong-fang, CAO Fu-jun 2022, 48 (6):  149-157.  Abstract ( 205 )   PDF (7863KB) ( 110 )   Save Based on the deep neural network, this paper solved elliptic partial differential equations in complex regions. By realizing the deep feedforward artificial neural network, the appropriate loss function and neural network solution strategy was constructred, and the accurate and effective strategies as well as numerical methods for elliptic partial differential equations were put forward. This method simply needed to select a small number of sample points on the boundary and inside region as the training set, and the parameters of the neural network were learned iteratively to approximate the solution of the elliptic partial differential equation. Compared with the traditional numerical method, this method is mesh free and does not need to generate computational grid, so it is easy to deal with any complex computational region. Numerical examples show that this method can solve differential equation problems with complex regions and has good numerical accuracy. References | Related Articles | Metrics

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The convergence and estimations of tight frames in Hilbert K_modules DONG Fang-fang, PEI Rui-chang 2022, 48 (6):  158-163.  Abstract ( 75 )   PDF (1092KB) ( 105 )   Save The convergence of infinite series of inner products of tight frames, and the estimations of tight frames in Hilbert K_module are discussed, and some significant conclusions are obtained, especially the bilateral inequality. Finally, examples are given to illustrate the convergence. References | Related Articles | Metrics

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Free vibration characteristics analysis of a porous functionally graded material rotating Timoshenko beam in thermal environment TENG Zhao-chun, MA Ling-quan 2022, 48 (6):  164-171.  Abstract ( 157 )   PDF (5186KB) ( 161 )   Save For the porous functionally graded materials beam model with uniform pore distribution, the temperature dependence of material properties is considered and the physical neutral surface of the beam is determined firstly, then the governing differential equation of the transverse free vibration of porous functionally graded material Timoshenko beam is derived by using Hamilton principle when it rotates in thermal environment, and the dimensionless form of the governing differential equation is also obtained. Secondly, differential transformation method (DTM) is used to transform the dimensionless governing differential equations and its boundary conditions, and the equivalent algebraic characteristic equations including the dimensionless natural frequencies are obtained. The dimensionless natural frequencies of transverse free vibration of a porous functionally graded material rotating Timoshenko beam under four boundary conditions of clamped-clamped (C-C), clamped-simply supported (C-S), simply supported-simply supported (S-S) and clamped-free (C-F) in thermal environment are calculated. After degrading it the dimensionless natural frequencies obtained are compared with the calculated results in existing literatures, the validity and correctness of which are verified. Finally, the effects of boundary conditions, porosity, rotating speed, temperature, elongation ratio and gradient index on the natural frequencies of rotating porous functionally graded material Timoshenko beams are analyzed. References | Related Articles | Metrics