Top Read Articles

Published in last 1 year |

In last 2 years |

In last 3 years |

All

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）（478）       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

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）（234）       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

On the properties of nonsingular M-matrices ZHONG Qin Journal of Lanzhou University of Technology    2023, 49 (5): 163-166.   Abstract （195）      PDF（pc） （546KB）（196）       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

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 （172）      PDF（pc） （669KB）（211）       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

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

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）（331）       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

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 （163）      PDF（pc） （2613KB）（225）       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

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）（306）       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

Fault diagnosis for chemical process based on an improved LSTM neural network DU Xian-jun, QIU Xiao-yu Journal of Lanzhou University of Technology    2023, 49 (6): 72-79.   Abstract （155）      PDF（pc） （2999KB）（98）       Knowledge map    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. Reference | Related Articles | Metrics

Select

Organizational structure and mechanical properties of Al 2O 3 interfacially modified unidirectional fiber C/C composites JIA Jian-gang, NIU Chao, ZHANG Zhen, FU Fang-xing, PAN Zi-kang Journal of Lanzhou University of Technology    2023, 49 (6): 1-8.   Abstract （150）      PDF（pc） （5784KB）（126）       Knowledge map    Save In order to alleviate the brittleness of C/C composites, the unidirectional carbon fiber preform was treated with Boehm sol, and the Al 2O 3 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 Al 2O 3 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 C f(Al2O3)/C-3 sample reached 77.3 MPa, and the elongation reached 15%. 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

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 （146）      PDF（pc） （6063KB）（206）       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

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）（202）       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 （139）      PDF（pc） （3271KB）（198）       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

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 Journal of Lanzhou University of Technology    2023, 49 (5): 28-33.   Abstract （134）      PDF（pc） （1307KB）（76）       Knowledge map    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 m away∶ m change =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. 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）（265）       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

Magnetic resonance imaging effect of polystyrene-based magnetic nanoplastics ZHANG Long, LIU Hao-nan, GAO Bo, XIN Qi, TANG Jie, AI Chun-jin Journal of Lanzhou University of Technology    2023, 49 (5): 20-27.   Abstract （126）      PDF（pc） （5501KB）（89）       Knowledge map    Save For efficient cellular magnetic resonance imaging (MRI), a T2-weighted contrast agent based on polystyrene/Fe 3O 4 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. Reference | Related Articles | Metrics

Select

Influence of BRB reinforcement on seismic reduction of high-rise concrete frame-shear structure SONG Yu, KOU Heng, CHEN Qian-rui Journal of Lanzhou University of Technology    2023, 49 (5): 112-119.   Abstract （126）      PDF（pc） （4702KB）（135）       Knowledge map    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. 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 （125）      PDF（pc） （9472KB）（223）       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

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 （123）      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