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28 October 2023, Volume 49 Issue 5 Previous Issue    Next Issue

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Materials Science and Engineering

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Thermodynamical analysis of TiN precipitation in 21Cr ultra pure ferrite stainless steel SHENG Jie, WEI Jia-fu, MENG Ya-hui, LI Yu-feng, MA Guo-cai, LA Pei-qing 2023, 49 (5):  1-9.  Abstract ( 315 )   PDF (2905KB) ( 520 )   Save Number density and size distribution of non-metallic inclusion have important influences on processability and service behaviors of steel. The numerical modeling of TiN precipitation condition in 21Cr ultra-pure ferrite stainless steel was solved based on the basic solidification theory. Thermodynamic and kinetic formation conditions and precipitation laws of TiN were investigated theoretically. The findings showed that TiN is precipitated free in molten steel. Ti and N elements solute segregation occurs on the solid/liquid interface in the processing of solidification, which promote TiN precipitation starting as fs=0.15. The precipitate size of TiN is affected by Ti, N content, and cooling rate. TiN radius can be reduced by decreasing the initial content of Ti, N and increasing the solidification cooling rate, Ti, N element contents are more sensitive to the effect of TiN size, so the timing of the precipitation of TiN inclusions during solidification can be significantly delayed by reducing the initial content of N in molten steel. Therefore, the addition amount of Ti in molten steel can be adjusted to make the quantity and size of TiN more reasonable in manufacture. References | Related Articles | Metrics

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Kinetic behavior of lithium storage in ferric phosphide doped sulfide polyacrylonitrile LIU Wen-wu, XU Zhi-qiang, LEI Yi-xiao, ZHENG Ya-wen, DA Shi-ji, WU You-zhi 2023, 49 (5):  10-19.  Abstract ( 192 )   PDF (8282KB) ( 206 )   Save Fe-phosphide doped sulfide polyacrylonitrile (FeP@SPAN) was synthesized by high-temperature phosphating. The P—S chemical coordination constructed in FeP@SPAN enhances the compatibility between the HOMO level of the nucleophile S2－ and the LUMO level of the electrophilic reagent Li+ during the discharge process, reduces the bonding orbital σ level of the reduction product Li2S, and speeds up the kinetic behavior of lithium storage reaction in the positive electrode. The phase structure, electrochemical properties, and effects of FeP@SPAN cathode material on redox kinetics during battery operation were investigated. The results showed that FeP is connected with SPAN through the P—S bond, and the influence of FeP on the morphology of SPAN can be ignored. FeP@SPAN, as the positive electrode of the battery, effectively improves the conductivity of the battery, reduces the impedance of the positive electrode, alleviates the dissolution of polysulfide, and improves the redox kinetics. Compared with the initial SPAN positive electrode, the FeP@SPAN positive battery has an initial capacity of 1 285.8 mAh/g at A current density of 0.2 A/g, and can still maintain the capacity of 615.2 mAh/g after 500 cycles at1 A/g current density with the average capacity attenuation per cycle of 0.079%. References | Related Articles | Metrics

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Magnetic resonance imaging effect of polystyrene-based magnetic nanoplastics ZHANG Long, LIU Hao-nan, GAO Bo, XIN Qi, TANG Jie, AI Chun-jin 2023, 49 (5):  20-27.  Abstract ( 142 )   PDF (5501KB) ( 115 )   Save For efficient cellular magnetic resonance imaging (MRI), a T2-weighted contrast agent based on polystyrene/Fe3O4 nanoparticles was developed. Two kinds of nanoplastic models with different sizes were prepared by double miniemulsion polymerization and dispersion polymerization, respectively, and the cell MRI was performed on them. The results showed that: with the increase of the exposure concentration of the nano-plastic model, the pseudo-color images of labeled mouse macrophages showed significant negative contrast enhancement, enhanced darkness of the gray image, and a gradual decrease in the intensity of MRI signal. The results of the ICP analysis confirmed that the uptake of the nanoplastic model by mouse macrophages increased with the increase of sample concentration. The polystyrene magnetic nanoplastic model can provide a new perspective for the cell MRI imaging of nanoplastics. References | Related Articles | Metrics

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Preparation and properties of1-vinyl-3-acetaldehyde glycol imidazole ionic liquid polymer membrane ZHANG Mei-ju, ZHANG Ding-jun, LI Wen-jie , SONG Wei, LENG Xiao, ZHANG Jing 2023, 49 (5):  28-33.  Abstract ( 148 )   PDF (1307KB) ( 98 )   Save Bromo-1-vinyl-3-acetaldehyde glycol imidazole ionic liquid was synthesized from N-vinylimidazole and bromo-acetaldehyde glycol in a one-step process. A variety of ionic liquid polymer membranes were prepared by modifying them with homopolymerization and copolymerization. The monomer structure of ionic liquid was characterized by infrared spectrum. The water resistance, adhesion and hardness of ionic liquid polymer film were tested and analyzed. The results showed that the properties of ionic liquid polymer film are related to the amount of modifier, and the mass ratio of ionic liquid modifier maway∶mchange =3∶10, the adhesion of the corresponding film is the strongest, when the mass ratio of ionic liquidmodifier is 2∶5, the water resistance is the best. this product can be daubed on the surface of OPP, PE plastic and glass plate to enhance their water resistance, adhesion and hardness. References | Related Articles | Metrics

Mechanical Engineering and Power

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Fault diagnosis method of rolling bearing based on 1D-LeNet-5 model GUO Jun-feng, SUN Lei, WANG Miao-sheng, XU De-feng 2023, 49 (5):  34-41.  Abstract ( 171 )   PDF (5120KB) ( 252 )   Save In the process of wind power generation, the normal operation of the bearing is related to the normal operation of the wind turbine. Aiming at the problem that the existing deep learning-based bearing fault diagnosis model has a complex structure and many parameters, which makes it difficult to train the model, an improved one-dimensional convolutional neural network rolling bearing fault diagnosis method based on the LeNet-5 model is proposed. First, in order to extract fault information to a greater extent, a short-time Fourier transform is introduced to preprocess the original vibration signal. Secondly, a one-dimensional network model is designed, which has a larger receptive field and faster calculation speed. At the same time, the Leaky-ReLU activation function is introduced to make the ability to process the details of the input signal stronger. The batch normalization layer and Dropout layer are added to improve the model generalization ability. Finally, the trained model is used to perform fault diagnosis experiments. The experimental results show that the diagnostic accuracy of this method can reach 99.98% in the classification of ten types of bearing faults, which has a good engineering application prospect for the fault diagnosis of wind turbine bearings. References | Related Articles | Metrics

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Research on transverse torsional coupling vibration of ball screw based on improved transfer matrix method WU Qin, LUO Dian-li, YANG Ran-ran 2023, 49 (5):  42-49.  Abstract ( 128 )   PDF (2839KB) ( 202 )   Save The traditional 2~4-order transfer matrix method can only be used to study the single degree of freedom vibration of beam systems. If it is directly applied to the study of beam systems with coupled vibration,a large error will exist in the calculation results of the natural frequencies of the system. In order to solve this problem, the ball screw feed system of the machine tool is taken as the research object in this paper, which is simplified and regarded the ball screw as a flexible beam. Based on considering the moment of inertia and transverse shear deformation of the beam, the traditional 2~4-order transfer matrix method is improved to 6-order by using Timoshenko beam theory. The mechanical and theoretical model of the system is established, and the system state transfer matrix equation including transverse vibration and torsional vibration is obtained. By comparing the simulation results and experimental results of the first two natural frequencies of the system, the accuracy and rationality of the improved transfer matrix method are verified. In addition, the influence of load on the first two natural frequencies of the system and the transverse torsional coupling vibration modes of the ball screw are studied through numerical simulation, and the transverse torsional coupling vibration characteristics of the ball screw are explored. References | Related Articles | Metrics

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Prediction of coke oven gas generation based on Seq2Seq WANG Wen-ting, LIU Shu-jun, ZHANG Yao-cong, DU Xiao-ze, XU Tong 2023, 49 (5):  50-58.  Abstract ( 157 )   PDF (4819KB) ( 232 )   Save To achieve accurate prediction of by-product gas in the steel production process, a sequence-to-sequence based deep learning model is constructed here. The hidden state matrix is obtained by calculating the hidden state of the input sequence through the encoder, and then the prediction result is obtained by decoding it through the decoder. Input parameters with high correlation are analyzed according to grey correlation. For the characteristics of unstable fluctuations in steel production, box line plots and hampel filtering are used to process extreme outliers and abrupt changes in the raw data, which are input to the model for single and multi-step prediction respectively. The results show that the prediction performance of the models based on the Seq2Seq structure is improved compared to their corresponding single models for single-step prediction, in which the LSTM2GRU model performs best for peak and valley fits. The LSTM2GRU model can effectively reduce the declining trend of model performance in multi-step prediction. Compared with the LSTM2LSTM model and the GRU2GRU model on two data sets, it is found that the root mean square error of the LSTM2GRU model has decreased by 5.3%, 5.6% and 9%, 7.7%, respectively. The mean absolute error of the LSTM2GRU decreased by 7.3%, 7% and 9.7%, 7.8%, respectively. Therefore, the LSTM2GRU model is more suitable for forecasting long-scale time series compared to other models. In addition, the introduction of the GRU structure into the model has improved prediction accuracy and reduced prediction time. References | Related Articles | Metrics

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Research on vehicle stability based on active steering and aerodynamics control GAO Wei, YU Wei, DENGZhao-wen, YI Qiang 2023, 49 (5):  59-66.  Abstract ( 154 )   PDF (3914KB) ( 326 )   Save Aiming at the problem of vehicle instability caused by tire saturation under extreme working conditions, an integrated control strategy based on active aerodynamic control and active rear wheel steering is proposed to improve the stability of vehicles on low-adhesion roads. The control strategy consists of an upper controller and a lower controller. The upper controller uses the two-degree-freedom model of the vehicle to determine the desired dynamic response. While, in the lower controller, a vehicle stability strategy with the coordination of active rear wheel steering and active aerodynamics is proposed. By building the CarSim/Simulink joint simulation model, the effectiveness of the discussed strategy is verified by selecting the double shift line condition and the drift condition. The results show that the designed coordinated control system can reduce the utilization of tires and effectively improve vehicle stability. References | Related Articles | Metrics

Chemical Industry and Light

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Optimal groove design of cylindrical gas seal based on approximate model ZHANG Wei-zheng, FENG Fan, REN Ya-nan, SUN Yue-yue 2023, 49 (5):  67-76.  Abstract ( 116 )   PDF (5441KB) ( 227 )   Save Aiming at the new type of cylindrical gas film seal with reverse herringbone groove on the side of rotating shaft sleeve, the mathematical model of cylindrical gas film seal was established and the pressure distribution of reverse herringbone groove gas film was numerically solved by finite difference method. Through the Isight platform integrated with MATLAB software, the optimal Latin hypercube test design and its post-processing module were used to extract the key groove structure parameters affecting the sealing performance parameters. An approximate model was established instead of time-consuming numerical calculation, and the multi-objective optimization of groove structure parameters was carried out by integrating the NSGA-Ⅱ multi-objective optimization algorithm, which provided theoretical reference for the multi-objective optimization design of groove type for cylindrical gas film seal slotted on the side of shaft sleeve. References | Related Articles | Metrics

Automation Technique and Computer Technology

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Robust H∞ control of DC microgrid with uncertain value bounds WANG Xiao-lan, CHEN Shuang 2023, 49 (5):  77-85.  Abstract ( 124 )   PDF (1835KB) ( 136 )   Save Aiming at the problem of parameter uncertainty in the DC microgrid, a robust H∞ control method based on LMI is proposed to ensure the stability of the DC bus voltage of the system. First,the norm-bounded uncertain small signal model of the DC microgrid is established. Secondly, according to the Lyapunov stability principle, the sufficient conditions for the existence of the LMI-based controller are derived. The design of the robust H∞ controller is transformed into an optimization problem with linear matrix inequalities, and then the state feedback control law is obtained, so that each subsystem and the associated large-scale system can be stabilized, anda feasible solution exists for the robust H∞ controller. Finally, numerical simulation is performed by Matlab to analyze the characteristics of the DC bus voltage under the change of microgrid structure, connection line parameters and load parameters, and verify the feasibility of the control method. References | Related Articles | Metrics

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Improve the LSTM trajectory prediction accuracy through an exponential weighted loss function ZHANG Tong, WANG Zhi-wen, LU Yan-rong, SUN Hong-tao 2023, 49 (5):  86-92.  Abstract ( 194 )   PDF (669KB) ( 253 )   Save Although a long-short-term memory (LSTM) network has been widely adopted to predict the vehicle trajectory, the iterative nature of LSTM introduces accumulative errors during training, resulting in a gradual decrease in the accuracy of trajectory prediction over time. Therefore, how to reduce the accumulative errors of the LSTM is a critical issue. To solve this problem, an exponential weighted loss function is used in this paper to weight the smoothed L1 loss function to reduce the cumulative error, enabling the model to predict the future trajectory of the vehicle more accurately, which is validated on US-101 and I-80 datasets from Next Generation Simulation (NGSIM). The simulation results show that the test dataset’s average error at 0.2 s and 5 s is reduced from 0.332 0 m and 7.716 8 m to 0.103 2 m and 6.624 3 m, respectively. The average prediction error is reduced by 14.16%, significantly reducing the cumulative error. References | Related Articles | Metrics

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Feature selection based on an improved Harris hawk optimization algorithm ZHAO Xiao-qiang, QIANG Rui-ru 2023, 49 (5):  93-101.  Abstract ( 182 )   PDF (1384KB) ( 357 )   Save Feature selection is a machine learning task that aims to reduce the number of features by removing irrelevant and redundant data while maintaining high classification accuracy. In order to address the problems that Harris hawk optimization algorithm (HHO) cannot perform feature selection in the discrete feature space, and that the population diversity is reduced and is easy to fall into local optimality in the later stage of the algorithm, a feature selection algorithm based on an improved Harris Hawk is proposed here. First, chaotic mapping is used to diversify the initial population to ensure that it can be evenly distributed in the search space under the premise of better population quality. Secondly, the position of the rabbit is re-updated by introducing a Gaussian mutation operator to avoid the algorithm falling into the local maximum. Finally, the binary version of the secondary optimization algorithm is designed and applied to the wrapped feature selection problem based on the KNN classifier. Through feature selection simulation experiments on 18 classic UCI data sets, the results show that the proposed algorithm in this paper can obtain better results than other mainstream algorithms in terms of fitness value, average classification accuracy and average feature selection number. So the proposed algorithm in this paper can effectively extract feature subsets and obtain more accurate data classification, and can achieve higher optimization accuracy. References | Related Articles | Metrics

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Coexistence analysis and image encryption of chaos-like attractors in conservative systems YAN Min-xiu, ZHANG Ping 2023, 49 (5):  102-111.  Abstract ( 155 )   PDF (9472KB) ( 254 )   Save It is very important to construct new conservative chaotic systems in engineering applications. On the basis of Hamilton’s generalized system theory, a chaotic system that is conservative in both energy and volume is proposed. After further analysis, it is found that the system has hidden chaotic attractors with strong characteristics and a large range of chaotic states. In addition, when the conservative chaotic system has sine function, cosine function or tangent function in the Hamiltonian energy function, it can produce an infinite number of coexisting chaotic attractors. Since the system exhibits good chaotic dynamics characteristics, it is suitable for engineering applications such as communication security and image encryption. Finally, the system is applied to image encryption, and the good security performance of the encryption algorithm based on this system is verified through qualitative analysis and quantitative analysis. References | Related Articles | Metrics

Architectural Sciences

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Influence of BRB reinforcement on seismic reduction of high-rise concrete frame-shear structure SONG Yu, KOU Heng, CHEN Qian-rui 2023, 49 (5):  112-119.  Abstract ( 139 )   PDF (4702KB) ( 151 )   Save Buckling-restrained braces are arranged on the existing high-rise frame-shear structure based on its working principle and mechanical properties. Designed by BRB bear story shear, the dynamic time history response of the structure, the energy consumption ratio of BRB, and the stress distribution of shear wall of the three different floor layouts under two different arrangments of single oblique and inverted V were studied with the aid of SAP2000 structural nonlinear finite element software. The analysis shows that the buckling-restrained brace at the lower part of the structure performs the shock-absorbing effect on the structure. In the case of rare earthquakes, buckling-restrained brace at the lower part of the structure can not only consume great energy, but also maximum reduce the stress of the shear wall under the peak response of the structure. The layout scheme can provide a reference for the engineering practice of flexural energy dissipation bracing for high-rise frame-shear structures. References | Related Articles | Metrics

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Influence of grouting in single pile on seismic performance of soil DENG You-sheng, PENG Cheng-pu, LI Ling-tao, LIU Jun-cong, YAO Zhi-gang 2023, 49 (5):  120-126.  Abstract ( 106 )   PDF (6528KB) ( 155 )   Save Soil liquefaction under earthquake is a common phenomenon. Grouting technique was used to the anti-liquefaction of soil and a numerical calculation model of single pile was established. The dynamic response of a single pile was studied under the combined load of El Centro seismic waves with different peak accelerations and a uniform load on the top of the pile, and the influence of grouting on seismic performance of soil in single pile model was cleared. The research results showed that most of the loess and sand would be liquefied under the action of the 0.3g El Centro seismic wave. The bearing capacity of the pile foundation increased by 15.4% after grouting to loess and sand around pile sides. Under the 0.3g El Centro seismic wave, the foundation rotates. After the grouting of soil, the center of rotation shifts upwards, reducing the maximum dynamic displacement of the soil at the top of the loess by 35.3% and increasing the top of the sand by four times. 0.2 seconds before the earthquake, there is a peak acceleration in the loess and sand, while in the later stage of the earthquake, the acceleration fluctuation is relatively small, and there is a certain amplification effect on the top surface of the foundation. After the soil is reinforced by grouting, this amplification effect is effectively suppressed. The research results can provide a reference for anti-liquefaction treatment by grouting. References | Related Articles | Metrics

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Numerical simulation on coarse sand bank collapse processes and shape response to gravitational erosion from a small desert watershed in the Upper Yellow River WANG Zhi-jun, ZHANG Ke, LI Yu-jie, ZHENG Jian 2023, 49 (5):  127-133.  Abstract ( 105 )   PDF (3989KB) ( 88 )   Save Using the digital elevation data of “Sudalaer”, a typical desert watershed from ten tributaries area in the Upper Yellow River, and taking the processes and types of loess bank as the reference group, the process and types of desert coarse sand bank collapse under steady rainfall infiltration conditions in the Upper Yellow River were studied through Strength Reduction Theory based generalized numerical simulation as well as field observation analysis. The results indicate that under the influence of cohesive force, the coarse sand bank slope is mainly in the state of layering and flaky slumping, while the loess bank slope is mostly in the state of block or mass slumping. Compared with the arc sliding of loess bank slope, the coarse sand bank slope presents a broken line sliding, and the collapse pattern is upright, which is qualitatively consistent with the measured results. References | Related Articles | Metrics

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Research on hysteretic performance of RC prefabricated beam-column joint with bolted connections DING Ke-wei, LIU Wen-jie, CHEN Wei 2023, 49 (5):  134-141.  Abstract ( 135 )   PDF (3029KB) ( 152 )   Save In order to study the hysteretic performance of RC prefabricated bolted beam-column joint,low-cyclic loading test was carried out at the beam end of this joint. Then the finite element analysis software ABAQUS is used to establish the three-dimensional finite element model of the joint followed with data analyzing. It is found that the data analysis results are in good agreement with the test results. On this basis,the test specimens are analyzed with variable parameters,and the seismic performance of the test specimens is analyzed by changing the bolt strength and the column concrete strength in the finite element model. The results show that the joint present good seismic performance in experiments and numerical simulations, which meet the seismic code requirements of strong column and weak beam. The increase of bolt strength can effectively improve the bearing capacity and energy dissipation capacity. Under the same loading system,the enhancement of column concrete strength has little effect on the hysteretic performance of the joint. With the same concrete strength of the beam and column, both hysteretic curves of the joints are full which behave great seismic performance. References | Related Articles | Metrics

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Analysis of horizontal and vertical bearing characteristics of inclined pile group based on numerical simulation SONG Yong-gang, WANG Jin-ke 2023, 49 (5):  142-149.  Abstract ( 236 )   PDF (4797KB) ( 265 )   Save Inclined pile, which has a relatively high horizontal bearing capacity, is widely used in cross-sea bridge, wharf, wind power station and other structures. In order to study the horizontal and vertical bearing characteristics of the inclined pile group, the finite element numerical model of 2×2 inclined pile group and 3×3 inclined pile group was established based on ABAQUS, and their horizontal and vertical bearing characteristics were studied respectively on the basis of verifying the correctness of the models by experiments. The results shows that: For the two pile group models, the larger the pile inclination angle (within 0~21°) is, the smaller the pile settlement under the same vertical load and the smaller the pile displacement under the same horizontal load. Inclined pile can effectively improve the vertical and horizontal bearing capacity of pile group. Under the same working condition, the pile displacements of the same position are similar, and the horizontal displacement of the pile decreases along the depth direction of the pile length. Due to the coupling effect of the displacement generated by the horizontal load and the displacement generated by the pile rotation, some piles have displacement in the direction opposite to the loading direction near the pile bottom. For the 2×2 pile group model and 3×3 pile group model, the increase of the number of piles does not lead to the proportional increase of the bearing capacity, and the “pile group effect” of horizontal loaded inclined pile group is similar to that of vertical loaded pile group. References | Related Articles | Metrics

Scientific

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Factor-square-full semimodules WANG Yong-duo, LU Jing 2023, 49 (5):  150-156.  Abstract ( 106 )   PDF (398KB) ( 147 )   Save As a proper generalization of factor-square-full modules, the concept of factor-square-full semimodules is introduced in this paper. Let S be a semiring and M a left S-semimodule. A proper subtractive subsemimodule X of M is said to be d-square if there exists a normal epimorphism f:M→(M/X)2; A proper subtractive subsemimodule X of M is said to be quasi-d-square if there exists a d-square subsemimodule Y such that X≤Y;M is said to factor-square-full if any proper subsemimodule is quasi-d-square. The properties of these subsemimodule classes and factor-square-full semimodules are discussed. References | Related Articles | Metrics

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Dimensions of complexes related to Gorenstein injective preenvelopes WU De-jun, ZHAO Xiao-yu 2023, 49 (5):  157-162.  Abstract ( 94 )   PDF (331KB) ( 216 )   Save Let R be an associative ring with identity and X be an R-complex. The definition and basic properties of the homological dimension of X related to the Gorenstein injective preenvelope are given, and the relationship between the homological dimension of X concerning Gorenstein injective preenvelope and the Gorenstein dimension of X is studied. References | Related Articles | Metrics

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On the properties of nonsingular M-matrices ZHONG Qin 2023, 49 (5):  163-166.  Abstract ( 243 )   PDF (546KB) ( 214 )   Save The relevant properties of nonsingular M-matrices and their minimum eigenvalues are given, based on the relationship between nonnegative matrices and M-matrices. Further, the lower bound for the minimum eigenvalues of nonsingular M-matrices is given by combining the famous Gerschgorin theorem and Hölder inequality. Numerical examples are given to illustrate the effectiveness of the discussed method. References | Related Articles | Metrics

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Projectively coresolved Gorenstein AC-flat modules over triangular matrix rings QIN Jun-xia, ZHANG Cui-ping 2023, 49 (5):  167-172.  Abstract ( 135 )   PDF (645KB) ( 197 )   Save The concept of projectively coresolved Gorenstein AC-flat modules is introduced (PGACF-modules for short), and the equivalent condition of these modules is given. Let $\boldsymbol{T}= \left(\begin{array}{ll}A & 0 \\ U & B\end{array}\right)$ be a triangular matrix ring, where A and B are rings, and U is a (B,A)-bimodule. Under some conditions, it is demonstrated $M=\left(\begin{array}{l}M_{1} \\ M_{2}\end{array}\right)_{\varphi^{M}} $ is a PGACF left T-module, then M1 is a PGACF left A-module, CokerφM is a PGACF left B-module and the morphism φM is a monomorphism; if the class of PGACF-modules is closed under extensions, the opposite case holds. References | Related Articles | Metrics