2020 volumne 41卷 Issue 06
XU Xianze, WANG Xingyu, LIU Panpan, ZHONG Ming
Abstract: Aiming to solve the shortcomings of alignment time-consuming and low precision in the coaxial debugging of existing optical fiber rod deposition machine tools, a set of automatic positioning and alignment device with high accuracy and high stability was designed and implemented. Firstly, the radial distortion and tangential distortion were eliminated by the Zhang′s calibration method. Then, in order to eliminate the influence of noise and background on the subsequent processing, the images were pre-processed using Gaussian filtering, dynamic threshold and Canny edge detection to extract accurate image edges. Finally, a new arc classification circular detection algorithm was used to achieve the precise positioning of the center of the measured surface in the image. The scale and deviation of the image were determined according to the fitted circle; and the position of the machine tool chuck was adjusted to achieve the center alignment of both ends of the machine tool. When the camera resolution was 500×104, comparing the algorithm in this paper with several common circle detection methods, the average error and average positioning time of our algorithm were 0.047 mm and 244 ms, respectively, indicating that this algorithm was much better than other detection algorithm. The experimental results showed that the accuracy and efficiency of the device for machine tool alignment were significantly improved. When the camera resolution was 500×104, the system detection accuracy was less than 0.1 mm. This work could meet the requirements of machine tool coaxial inspection, and provide a fast and effective method for machine tool coaxial debugging.
LI Yang1,2, PENG Xiaoyong1,2, LI Dalei1,2, LU Jinsheng3, ZOU Yun1,2
Abstract: The metalloscopy and microhardness method could not meet the needs of whole testing of nitriding thickness of 40Cr steels products. A laser ultrasonic measurement was proposed to measure the nitriding thickness non-destructively through the dispersion of surface waves. Firstly, the surface waves were excited on the 40Cr steels with different nitriding thickness, and then the surface waves were received by laser interferometer. So the signals of surface waves were excited and received contactless. Finally, the disperse curves of surface waves were extracted by 2D-FFT. It was found that the phase velocity of surface waves increased as the nitriding thickness increased. The dispersion of surface waves with low frequencies was higher than that with high frequencies. The velocity of surface waves would not change when the nitriding thickness was higher than 394 μm. The relationship between the disperse curves of surface waves and the nitriding thickness, could be used to measure the nitriding thickness. Therefore, the laser ultrasonic was a feasible method to measure the nitriding thickness of 40Cr steel non-destructively, and it had value in engineering applications.
ZHANG Sanchuan1,YE Jianming2,SHI Yanjuan1
Abstract: In order to study the feasibility of millimeter wave radar for vehicle forward collision avoidance detection, a forward collision avoidance device was designed based on 77 GHz millimeter wave radar. Aiming at the low frequency leakage wave signal and high frequency interference signal, the device used analog signal processing module and other hardware systems for preliminary filtering. On this basis, the distance and speed of the target were obtained through the processing of FIR digital filtering, FFT transform, constant false alarm detection and other digital algorithms. At the same time, a multi-stage pre-warning model and method was constructed based on millimeter wave radar azimuth detection principle and driving safety distance model for the forward collision condition of passenger cars on structured roads. Road test showed that the distance detection error of the device designed for static target was 4.5%, and the maximum error was 5% for detecting two dynamic targets at the same time. Therefore, it was feasible for 77 GHz millimeter wave radar to be used in the design of vehicle anti-collision warning system.
ZENG Falin1,2, CAI Jiawei2, SUN Sumin2
Abstract: In order to predict the sound quality of automobile unsteady exhaust noise, 2G WOT and 3G WOT tests were conducted. The main factors of satisfaction level were analyzed. Via the correlation analysis, internal relations between the psychoacoustic objective parameters and the subjective evaluation were revealed. The complementary ensemble empirical mode decomposition(CEEMD) was used to decompose the signals of the accelerated exhaust noise, obtaining multiple IMF components and calculating sample entropy of the IMF components. In order to reduce the possibility of redundancy and retain the main features of the original data, principal component analysis(PCA) was applied to reduce dimension of data, so as to establish a new sound quality parameter SQP-CSP(sound quality parameter base on CEEMD and then proceed SE-PCA). Meanwhile, the genetic algorithm(GA) was used to optimize the weights and thresholdsin BP neural network, so that a GA-BP was developed to predict the sound quality of the accelerated exhaust noise. In order to validate the newly extracted unsteady exhaust noise features,the psychoacoustic parameters were also taken as the model’s inputs to predict the sound quality.The results showed that the model based on the new parameters had higher accuracy for predicting the sound quality of unsteady exhaust noise.
SUN Xiaoyan, NIE Xin, BAO Lin, CHEN Yang
Abstract: The conversion rate prediction (CRP) of mobile APP advertising was challenging due to the high-dimension, sparsity, and high interactions. Motivated by this an improved Wide&Deep model was proposed by fusing field-aware factorized machine (FFM) and deep convolutional neural network (DCNN) to effectively and automatically obtain the lower-order and higher-order interactions of high-dimensional sparse features, so as to realize the automatic and efficient combination of features and improve the accuracy of CRP. The framework of the proposed algorithm was first delivered, and a feature combination algorithm based on the width module FFM to extract the interactive relations of lower-order features was presented for the embedded sparse data. The extraction of the higher-order interactive features based on a DCNN was further given by fusing the latent features obtained by the FFM. Finally, the interactive feature combinations obtained by width and depth modules were integrated for the CRP. The application of the proposed algorithm in predicting the conversion rate of Tencent′s mobile APP advertisements demonstrated the effectiveness of the method.
YANG Wenqiang, ZHANG Sujun, GUO Hao
Abstract: To improve the efficiency of warehousing operation, inspired by biological evolutionism, a new method of multispecies co-evolution algorithm (MSCA) based on genetic algorithm, particle swarm optimization algorithm, and artificial fish swarm algorithm was proposed to solve warehousing operation optimization problem with cross aisles in this paper. It improved the ability of each species to adapt to one′s environment based on multispecies competition-predatory strategies by learning mechanism; and could improve the population diversity of all the species cooperatively using mutation mechanism. It enchanced evolutional capacity of single species, and further improved the global search ability and solving efficiency of MSCA. Finally, industrial example showed the effectiveness of the proposed algorithm.
WANG Shenwen1,2, WANG Jiaying1,2, ZHANG Jiaxing1,2, WANG Feng3, WANG Hui4
Abstract: The multi-objective optimization problem became more and more complex. Inspired by the ensemble algorithm, a multi-objective differential evolution algorithm with elite-archive and opposition-based learning is proposed in this paper. In this algorithm, an external archive was created to save the nondominated solutions in the evolutionary process of the population. It used the preset opposition-based generation jumping andopposition-based learning to generate the different solutions of the individual and stored in the elite archive, to expand the search scope and improve population diversity. The grid was used to determines the coordinates of the solutions, and the restricted mating pool was generated according to certain constraints. The parent solutions were selected in the restricted mating pool to produce the new individual by using differential evolution algorithm, then generated the next iteration population by constrained decomposition with grids sorting. The experimental results showed that the proposed algorithm had strong robustness with the shapes of PFs in solving unconstrained multi-objective optimization problems was superior to some state-of-the-art multi-objective algorithms in diversity and convergence on UF test problems.
ZHONG Wei1, LIU Xin1, GAO Zihe2
Abstract: In this paper, a 1∶10 scale tunnel was adopted to investigate the influence of longitudinal ventilation on the fire behavior in tunnel and the natural smoke exhaust by vertical shaft. Results showed that the flame inclination and the mass loss rate of fire changed with the ventilation velocity and shaft height, which further influenced the temperature distribution and smoke exhaust velocity through the shaft. Once plug-holing occurred, the fresh air in the lower of tunnel would be exhausted through the shaft directly, greatly reducing the smoke exhaust effect. On this basis, the critical Froude number proposed by Hinckley was improved, and the critical Froude number for natural exhaust by shaft under the longitudinal ventilation was determined as 3.2. For Froude number in the range of 3.2 to 5.1, plug-holing occurred, while for Froude number in the range of 0.6 to 3.2, there was no plug-holing.
CHEN Zeqin1, LIU Guoming2
Abstract: The Gudehus-Bauer hypoplastic constitutive model and its parameters were introduced briefly. Based on the Gudehus-Bauer hypoplastic constitutive model, the relationships between the parameters α, β and the confining pressure were established. The triaxial compression test curves of rockfill materials were simulated with the Gudehus-Bauer hypoplastic constitutive model and compared with the test values. According to the simulation results, a volumetric strain control term was added to the model, which improved the triaxial compression test volumetric strain curve of rockfill material simulated by he Gudehus-Bauer hypoplastic constitutive model. The stress-deformation analysis of CFRD was performed by the modified Gudehus-Bauer hypoplastic constitutive model with 3D Nonlinear finite element, and the results were compared with the double-yield surface model and Duncan E-B model. The numerical results indicated that the settlement, the horizontal displacement distribution and the principal stress distribution calculated by the modified Gudehus-Bauer hypoplastic constitutive model were close to the Shen Zhujiang’s double-yield surface model. Meanwhile, it could overcome the problem of higher tensile stresses at the bottom of face slabs calculated by the Duncan E-B mode in storage period.
ZHU Yuanyuan, WANG Xiaomei
Abstract: In the case of geometric nonlinearity and local thermal non-equilibrium, thermodynamic characteristics for an incompressible fluid-saturated porous thermo-elastic half-plane subjected to a surface temperature loading were studied. Firstly, the mathematical model of problem was established based on the Porous Media Theory. Then a synthetical numerical computation method was presented to simulate the numerical results of problem, in which, the differential quadrature method and the second-order backward difference scheme were applied to discretize mathematical model on the spatial and time domain, respectively. The Newton-Raphson iterative method was finally used to solve the nonlinear algebraic equations and to present the numerical results of the problem. The study pointed out that the solution method was effective and reliable. The advantages of the presented method, such as little calculated amount and high accuracy, could be proved. Finally, the thermodynamics characteristics for a fluid-saturated porous thermo-elastic half-plane subjected to the surface temperature loadings were studied, the effects of material parameters and geometric nonlinearity on the dynamic characteristics were considered in detail.
ZHANG Jian1, ZHANG Yuxiao1, ZHU Yongsheng2, XIONG Zhuangzhuang3, XIE Jiaxin1, ZHU Fangyuan1
Abstract: In view of the high permeability of new energy and the low coupling performance between electrity and gas systems in the IEGS, a robust optimization model of the integrated energy system of electricity and gas was proposed in this paper to improve the consumption of new energy, and strengthen, flexible conversion between electricity and gas energy. An electric-gas demand side load response model was established considering the price constraint coefficient, and using the second-order cone and McCormick method to convert the original mixed integer nonlinear model into a linear model. Scene screening rules was used to add the uncertainty of new energy, The IEEE 33-node power grid and the Belgian 20-node natural gas network interconnection system were modified, analyze and compare The model′s profit, electricity-to-gas capacity and power consumption rate, and the robustness of the system were analyzed and compared. It had a great advantage in nature and could better cope with the volatility of new energy.
LI Dewei, ZAI Xiangwei, ZHANG Sheng, SUN Tong, CHU Junying, LIU Zhiping
Abstract: Considering the lack of data, poor information and low precision in the risk analysis of traditional railway signal equipment, The fuzzy number theory was introduced in this paper based on the failure mode effects and criticality analysis (FMECA), introduction. The application of grey correlation degree method, and the variable weight comprehensive method proposes were integrated into this risk assessment method based on the fuzzy gray theory. This method combined fuzzy theory and gray theory, could effectively reduce the dependence on a large amount of equipment failure data. Compared with the traditional risk priority index (RPN), the risk with the same RPN value could be identified by introducing the variable weight principle. Taking the ZPW-2000A track circuit as an example, the failure modes of its important equipment and the corresponding risk levels were analyzed, and the gray ranking was performed. The results showed that the risk priority index (RPN) level obtained by the risk assessment method based on fuzzy gray theory was more refined than that obtained by the traditional method (RPN). This method could well identify its two major signal failure escalation modes. The traditional method could only identify one of them. Therefore, the method proposed was more effective for risk identification.
SHI Ruxin1, WANG Deshun2, YU Tao1, XUE Jinhua2, FENG Xinzhen2, DOU Chunxia3
Abstract: Aiming to reduce large forecast error in current photovoltaic power generation forecast, based on wavelet decomposition-NARX neural network combined prediction method was proposed. The historical PV sequence was decomposed into high frequency and low frequency components by wavelet decomposition, and the high and low frequency data were used as NARX neural network input, and PV output power was used as neural network output to train and obtain the predicted output. Then wavelet reconstruction was used to derive PV power generation prediction data. The simulation results showed that prediction error of new combined prediction algorithm was 1.47% lower than that of traditional BP neural network, and new prediction algorithm could reduce running time by nearly 5 s.
WANG Jianjian, YAN Jiejie, ZHANG Chong, XI Jingyu, ZHAO Jianhong, SONG Chengying
Abstract: Interfaces play vital role in various electrocatalysis and thus exploring cheap and facile method for fabricating interfaces is of great significance. In this study, a wet-chemistry method for fabricating Pd/CeO2 interfaces is proposed, in which Pd was in-situ reduced by Sn(OH) 2 while CeO 2 was formed through Ce 3+ enrichment and homogeneous precipitation onto Sn(OH) 4 that is transformed from Sn(OH) 2. The introduction of CeO2 is confirmed by scanning electron microscope , energy-dispersive spectroscopy and X-ray photoelectron spectroscopy. Electrochemical characterization shows that CeO2 replace SnO 2 surface and hardly lowers the electrochemical active surface area of Pd, meaning t hat me<x>tal oxides with poor electrical conductivity can be used by this fabrication method. Considering that Pd/CeO2 and Pd/SnO 2 are two widely used interfaces in electrocatalysts, Pd/CeO 2 and Pd/SnO 2 are further compared in terms of formate and ethanol oxidation using cyclic voltammetric and chronoamperometric measurement. It shows that Pd/CeO2 is more active than Pd/SnO 2 for formate and ethanol oxidation, the reason for which might be ascribed to Pd/CeO 2 interface that prohibits CO adsorption. We believe that the present study could provide simple avenue for fabricating interfaces between noble me<x>tals and me<x>tal oxides even with poor electrical conductivity.
LI Shasha1, CHANG Yingjie2, ZHAO Jie1, DING Yuanmin1, LI Ruipeng2, LI Wen2,3,4,5
Abstract: Tetracaine hydrochloride has polymorphic phenomena. The measurement of the solubility of crystalline drugs was a hot topic in the field of drug quality control. The solubility of commercial tetracaine hydrochloride was reported in the literature. The solubility of tetracaine hydrochloride was determined and correlated. On the basis of qualitative and quantitative analysis of polymorphic phenomena of tetracaine hydrochloride, balance method was selected to determin the solubility of commercial tetracaine hydrochloride in pure and mixed solvents. The results showed that tetracaine hydrochloride had the latent dissolution phenomenon in methanol-ethyl acetate mixed solvents. When the molar fraction of methanol was 0.849 2, the solubility reached the maximum. In pure solvents, the solubility datas of tetracaine hydrochloride coincided with the Apelblat equation. While in mixed solvents, the solubility datas of tetracaine hydrochloride coincided with the CNIBS/R-K equation.The correlation coefficients R2 between fitting results and experimental data was greater than 0.99. The dissolution entropy and enthalpy of tetracaine hydrochloride in the dissolution process were calculated by the van′t Hoff equation, which proved that the dissolution process of tetracaine hydrochloride was endothermic and entropy-driving.
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