Most Down Articles

Published in last 1 year| In last 2 years| In last 3 years| All| Most Downloaded in Recent Month | Most Downloaded in Recent Year|

Published in last 1 year

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

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 Journal of Lanzhou University of Technology    2023, 49 (5): 1-9.   Abstract （299）      PDF（pc） （2905KB）（480）       Knowledge map    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 f s=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. Reference | Related Articles | Metrics

Select

Effect of ultrasonic treatment on microstructure and properties of degradable Zn-0.5Sr alloy LIU Jian-jun, ZHANG Peng-tao, ZHAO Zhi-xin, ZHANG Jiao, LI Qing-lin, DING Yu-tian Journal of Lanzhou University of Technology    2024, 50 (1): 1-9.   Abstract （163）      PDF（pc） （6577KB）（332）       Knowledge map    Save The effects of different ultrasonic power (0,300,600,900 W) on the microstructure and corrosion properties of Zn-0.5Sr alloy were studied. The results show that the SrZn 13 phase in the as-cast Zn-0.5Sr alloy changes from coarse polygon to fine block after ultrasonic treatment.Compared with the untreated alloy, the electrochemicalcorrosion rate of the alloy increases from 2.078±0.141 mm/a to 5.747±0.390 mm/a when the ultrasonic power is 600 W.The immersion corrosion rates of Zn-0.5Sr alloy after 15 and 30 days are0.090±0.002 1、0.074±0.001 9 mm/a, respectively, which are 1.88 times and 1.95 times higher than that of the untreated alloy. Reference | Related Articles | Metrics

Select

Feature selection based on an improved Harris hawk optimization algorithm ZHAO Xiao-qiang, QIANG Rui-ru Journal of Lanzhou University of Technology    2023, 49 (5): 93-101.   Abstract （159）      PDF（pc） （1384KB）（307）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Research on vehicle stability based on active steering and aerodynamics control GAO Wei, YU Wei, DENGZhao-wen, YI Qiang Journal of Lanzhou University of Technology    2023, 49 (5): 59-66.   Abstract （133）      PDF（pc） （3914KB）（270）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Analysis of horizontal and vertical bearing characteristics of inclined pile group based on numerical simulation SONG Yong-gang, WANG Jin-ke Journal of Lanzhou University of Technology    2023, 49 (5): 142-149.   Abstract （219）      PDF（pc） （4797KB）（235）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Fault diagnosis method of rolling bearing based on 1D-LeNet-5 model GUO Jun-feng, SUN Lei, WANG Miao-sheng, XU De-feng Journal of Lanzhou University of Technology    2023, 49 (5): 34-41.   Abstract （146）      PDF（pc） （5120KB）（234）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Research on efficiency prediction method of reciprocating air compressor based on digital twin technology YU Jian-ping, HU Shuang, LIU Xing-wang, TIAN You-wen, QIU Hong-wei, AKOTO Emmauel Journal of Lanzhou University of Technology    2024, 50 (1): 48-52.   Abstract （165）      PDF（pc） （2613KB）（227）       Knowledge map    Save The method for compressor efficiency prediction and parameter optimization by establishing the reciprocating air compressor digital twin model has the advantage of flexibility, low cost, and good versatility. However, the traditional twin model based on the BP neural network (BPNN) has lots of shortcomings, such as longer training time to establish a module, easily falling into the local optimal solution, and difficulty in achieving the global optimal solution. To solve these problems, a novel digital twin model based on the CIWOA-BPNN algorithm is put forward to determine the key indexes by the principal component analysis method, in which a CIWOA algorithm is introduced to improve the BPNN’s performance. The results show that the new CIWOA-BPNN twin model effectively avoids falling the local optimal problem. The relative error of CIWOA-BPNN is less than 0.6%, and the coefficient of determination is 0.997 75, which greatly improves the prediction accuracy compared with the traditional model. Reference | Related Articles | Metrics

Select

Coexistence analysis and image encryption of chaos-like attractors in conservative systems YAN Min-xiu, ZHANG Ping Journal of Lanzhou University of Technology    2023, 49 (5): 102-111.   Abstract （126）      PDF（pc） （9472KB）（226）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Improve the LSTM trajectory prediction accuracy through an exponential weighted loss function ZHANG Tong, WANG Zhi-wen, LU Yan-rong, SUN Hong-tao Journal of Lanzhou University of Technology    2023, 49 (5): 86-92.   Abstract （175）      PDF（pc） （669KB）（213）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Microstructure and properties of TiNbVMo-(Zr, Cr) refractory high entropy alloys for nuclear application LI Ji-jing, HU Shi-wen, LIU De-xue Journal of Lanzhou University of Technology    2024, 50 (2): 1-8.   Abstract （147）      PDF（pc） （6063KB）（209）       Knowledge map    Save Three novel ductile and single-phase BCC structurerefractory high-entropy alloys (RHEAs)Ti 40Nb 25V 15Mo 5Zr 15 ,Ti 40Nb 30V 20Mo 5Zr 5 andTi 40Nb 30V 20Mo 5Cr 5were developed, and the alloy, exhibit good strength and toughness at room temperature,the alloy Ti 40Nb 25V 15Mo 5Zr 15has a maximum tensile strength of 1 037 MPa. With the decrease of Zr content, the fracture elongation of Ti 40Nb 30V 20Mo 5Zr 5increases from 8.94% to 13.96%.A single layer of corrosion diffusion is only formedafter a static lead-bismuth saturated oxygen corrosion testto Ti 40Nb 30V 20Mo 5Cr 5at 450 ℃ for 100, 300, and 700 h.The thickness of the corrosion layer dno't change significantly with time. Reference | Related Articles | Metrics

Select

Dimensions of complexes related to Gorenstein injective preenvelopes WU De-jun, ZHAO Xiao-yu Journal of Lanzhou University of Technology    2023, 49 (5): 157-162.   Abstract （86）      PDF（pc） （331KB）（207）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Prediction of coke oven gas generation based on Seq2Seq WANG Wen-ting, LIU Shu-jun, ZHANG Yao-cong, DU Xiao-ze, XU Tong Journal of Lanzhou University of Technology    2023, 49 (5): 50-58.   Abstract （144）      PDF（pc） （4819KB）（204）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Research on configuration optimization design method of hybrid electric vehicle ZHAO Si-li-gen, WANG Jing-yuan, ZHANG Xiao-ming Journal of Lanzhou University of Technology    2024, 50 (1): 60-67.   Abstract （142）      PDF（pc） （3271KB）（202）       Knowledge map    Save According to the relationship between the structural characteristics and dynamic characteristics of planetary gear vehicle, a theoretical design method of power system configuration of hybrid electric vehicle was proposed. Firstly, all the connections in the configuration are divided into three categories, and the matrix representation is used to represent these connections to reflect the system dynamics and the physical structure of the configuration. Subsequently, a matrix representation method for automatic configuration design is proposed. The speed equation is obtained through matrix operation, and consequently, various configurations of automobile double planetary gear structures are obtained. Finally, the effectiveness of this approach is validated through simulation. Results indicate that with the support of the matrix representation method, the optimal configuration can be selected automatically by computer, which avoids manual calculation and comparison, thereby conserving significant effort and time. Reference | Related Articles | Metrics

Select

On the properties of nonsingular M-matrices ZHONG Qin Journal of Lanzhou University of Technology    2023, 49 (5): 163-166.   Abstract （199）      PDF（pc） （546KB）（198）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Research on transverse torsional coupling vibration of ball screw based on improved transfer matrix method WU Qin, LUO Dian-li, YANG Ran-ran Journal of Lanzhou University of Technology    2023, 49 (5): 42-49.   Abstract （112）      PDF（pc） （2839KB）（195）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Optimal groove design of cylindrical gas seal based on approximate model ZHANG Wei-zheng, FENG Fan, REN Ya-nan, SUN Yue-yue Journal of Lanzhou University of Technology    2023, 49 (5): 67-76.   Abstract （100）      PDF（pc） （5441KB）（194）       Knowledge map    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. Reference | Related Articles | Metrics

Select

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 Journal of Lanzhou University of Technology    2023, 49 (5): 10-19.   Abstract （166）      PDF（pc） （8282KB）（191）       Knowledge map    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 S 2－ and the LUMO level of the electrophilic reagent Li + during the discharge process, reduces the bonding orbital σ level of the reduction product Li 2S, 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%. Reference | Related Articles | Metrics

Select

Reliability research of wind turbine based on PAC-FSEM method ZHENG Yu-qiao, LANG Qi-fa, SHI Cheng-long, LIU Yu-hang, LIU Yan-jie Journal of Lanzhou University of Technology    2024, 50 (1): 35-40.   Abstract （100）      PDF（pc） （1195KB）（187）       Knowledge map    Save Based on the relevant operating data from a wind farm in Northwest China, the reliability of wind turbines is studied. Considering the correlation and redundancy among operating data, Principal Component Analysis (PCA) method was used to reduce dimensionality, and some key reliability indicators were selected. Subsequently, a reliability evaluation model is constructed utilizing fuzzy theory in conjunction with the selected key indicators from operational data. A subset of wind turbine operating data is selected for model verification. The research results show that the PCA method extracts the principal component with a cumulative variance contribution rate of 87.585%, which can comprehensively express the reliability information of wind turbines. In the evaluation of a single reliability index, the availability of B02 is as high as 98%, but its total power generation is the lowest. Conversely, the availability of A04 is the lowest in the available area yet relatively higher power generation, indicating potential discrepancies when assessing reliability based on single reliability index. All indicators of A05 and B03 are high, the actual operation state of which is good, and the power generation is high, indicating that their comprehensive reliability is higher, which is consistent with the research results. Therefore, the fuzzy theoretical evaluation model (FSEM) of wind turbine reliability established based on PCA and fuzzy theory is in line with the actual operating state and has guiding significance for quantitatively evaluating the reliability of wind turbines. Reference | Related Articles | Metrics

Select

Interior elements in topological systems with its applications BAI Rong-rong, WU Hong-bo Journal of Lanzhou University of Technology    2024, 50 (1): 146-151.   Abstract （68）      PDF（pc） （421KB）（179）       Knowledge map    Save The concept of interior elements of subsets has been introduced in topological systems, and the related properties of interior elements have been discussed. The operator of interior elements has been defined by extent mapping and interior element mapping between a set and a frame, and the method determining topological system by the operator of interior elements has been given. The continuous mapping between topological systems is characterized by the interior elements of topological systems. Reference | Related Articles | Metrics

Select

Projectively coresolved Gorenstein AC-flat modules over triangular matrix rings QIN Jun-xia, ZHANG Cui-ping Journal of Lanzhou University of Technology    2023, 49 (5): 167-172.   Abstract （124）      PDF（pc） （645KB）（174）       Knowledge map    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 M 1 is a PGACF left A-module, Coker φM 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. Reference | Related Articles | Metrics