Table of Content

28 August 2020, Volume 54 Issue 8 Previous Issue    Next Issue

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Defecation Perception Reconstruction of an Artificial Anal Sphincter System ZHU Dong, JIANG Pingping, YAN Guozheng, WANG Zhiwu, HAN Ding, ZHAO Kai, HUA Fangfang, YAO Shengjian, DING Zifan, ZHOU Zerun 2020, 54 (8):  771-777.  doi: 10.16183/j.cnki.jsjtu.2019.222 Abstract ( 1326 )   HTML ( 2154 )   PDF (10730KB) ( 369 )   Save To overcome the shortcomings of data acquisition and analysis methods in the existing artificial anal sphincter system, a fecal perception reconstruction system is designed. The system mainly includes the design of a sensor module, a data acquisition and storage module, and a data analysis algorithm. Through the cooperation of the multi-sensor data acquisition and the storage module, the distribution of rectal surface pressure is reconstructed. A fecal perception prediction model based on principal components analysis (PCA) and support vector machines (SVM) is proposed (PCA-SVM). The results show that the axial and radial pressure signals of the upper arm and the radial position of the middle arm are significantly related to the fecal perception. The SVM algorithm based on the Gauss kernel function and the penalty factor C=0.0595 and the width σ=0.9536 pairs of effective pressure indicators are selected. Compared with the feed-forward neural network model, the vector model has a higher prediction accuracy and meets the requirements of the fecal perception function of the artificial anal sphincter system. Figures and Tables | References | Related Articles | Metrics

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Effect of Deposition Process on Electrical Properties of Polyaniline Coating and Its Wear Resistance LI Wei, ZHANG Wenguang, YU Qian, XIE Jie 2020, 54 (8):  778-784.  doi: 10.16183/j.cnki.jsjtu.2019.072 Abstract ( 973 )   HTML ( 182 )   PDF (3590KB) ( 383 )   Save The surface coating of the nerve electrode has an important influence on the performance of the electrode, and the deposition process is an important influencing parameter. This paper focuses on the effect of coating deposition process on its electrical properties, and studies the wear resistance of the coating obtained by the best deposition process. Specifically, the advantages and disadvantages of the three polyaniline electrochemical deposition methods are compared under the premise of controlling the amount of charge passing through the electrodes during the deposition process. The results show that compared with the bare electrode, the impedance of the cyclic voltammetric deposition electrode decreases by 29.7% and the CV area increases by 4.05 times. The impedance of the constant current deposition electrode decreases by 39.8%, and the CV area increases by 5.4 times. The impedance of the constant potential deposition electrode decreases by 4.3% and CV area increases by 4.9 times. The constant current method works best. A lower impedance and larger CV area mean a better electrical performance. Under this standard, deposition is better while the deposition time of constant current is between 600 and 700 s. In order to investigate the effect of polyaniline coating on the performance improvement of the electrode after wear, this paper has designed a simulated internal wear device for related experiments. The results show that the electrical properties of the coating are gradually reduced during the wear process. After 4h of wear, the impedance of the modified electrode is even higher than that of the bare electrode. Therefore, the anti-wear properties of the coating should be taken into account in the evaluation of conductive coatings. Figures and Tables | References | Related Articles | Metrics

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Optimization Design of Flexible Neural Electrodes Based on Orthogonal Experimental Method XIE Jie, ZHANG Wenguang, YIN Xuele, LI Wei 2020, 54 (8):  785-791.  doi: 10.16183/j.cnki.jsjtu.2019.068 Abstract ( 731 )   HTML ( 9 )   PDF (912KB) ( 348 )   Save In order to optimize the design of flexible neural electrodes, three parameters of elastic modulus, electrode thickness, and wedge angle are comprehensively studied. The experimental groups are established based on orthogonal experimental design. The maximum strain of brain tissue in different experimental groups are evaluated by ANSYS. In addition, a new hybrid flexible electrode is designed based on the stimulation results. The experimental results reveal that when elastic modulus is 8.5GPa, thickness is 15μm and wedge angle is 45°, the maximum strain of brain tissue due to micromotion is the smallest, i.e., 5.5627×10-2. Moreover, a sandwich-type hybrid flexible neural electrode is designed with an elastic modulus of 8.5GPa on both sides and an elastic modulus of 5.5GPa in the intermediate layer. The sandwich-type structure can effectively reduce micromotion damage and implant deformation compared to the traditional electrode. Figures and Tables | References | Related Articles | Metrics

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Hybrid Ant Colony Algorithm for Batch Scheduling in Semiconductor Furnace Operation JIANG Xiaokang, ZHANG Peng, LÜ Youlong, ZHAO Xinming, ZHANG Jie 2020, 54 (8):  792-804.  doi: 10.16183/j.cnki.jsjtu.2018.232 Abstract ( 959 )   HTML ( 16 )   PDF (1744KB) ( 495 )   Save Furnace district is one of the main bottlenecks in semiconductor fabrication, which has a great influence on the entire production line. The current scheduling research in the furnace district mainly focuses on dispatching rules, and the constraints considered are relatively simple. The previous research ignores not only the multi-machine scheduling which contains front and rear procedures but also the re-entrant characteristic of the wafer fabrication. This paper focuses on the scheduling problem of β1→β2 type for minimizing the meaning flow time (MFT) in furnace district. The constraints consist of limited waiting time, incompatible families, and re-entrant flow. It builds a novel β1→β2 model about the scheduling problem, and decomposes the problem into three stages: batch forming, machine selecting, and batch sorting. An algorithm based on the hybrid ant colony optimization algorithm is proposed, which batches the jobs by using a variable threshold control strategy, and sorts these batches by a hybrid ant colony optimization algorithm. According to the results of 54 sets of different scales based on historical production data, it is concluded that the performance of the hybrid ant colony optimization (ACO) algorithm is better than several common heuristic rules and the genetic algorithm. The proposed hybrid-ACO algorithm is applied to the actual wafer production line, which can effectively reduce the water flow time in the production process. Figures and Tables | References | Related Articles | Metrics

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Influence of Parallel Impeller Inlet Trimming on Mixed Flow Pump as Turbine YANG Sunsheng, SHAO Ke, DAI Tao 2020, 54 (8):  805-812.  doi: 10.16183/j.cnki.jsjtu.2019.081 Abstract ( 777 )   HTML ( 12 )   PDF (8113KB) ( 219 )   Save To study the influence of impeller trimming on mixed flow pump as turbine, a turbine whose specific speed is 240 is designed. The impeller inlet has been trimmed in parallel for four times and its shroud and hub are retained. By using the method of CFD and test, the turbine performance is obtained and the internal flow of the mixed flow pump as turbine is analysed. The result shows that with the increase in the trimming ratio, the best efficiency point moves to the small flow region. In the small flow region, the shaft power rises and the head drops. In the large flow region, the shaft power drops and the head rises. The circulation flow between the impeller and the volute increases so that the highest efficiency of the turbine decreases. The theoretical formulas are used to predict the performance of the mixed flow pump as the best efficiency point of the turbine, and the efficiency and head are higher than those in the test results, with smaller errors. It can be found that the formulas of the impeller trimming of mixed flow pump are almost suitable for the impeller trimming of mixed flow pump as turbine. Figures and Tables | References | Related Articles | Metrics

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Thermal Analysis and Control of Transcutaneous Energy Transfer Modulus of Puborectalis-Like Artificial Anal Sphincter ZHOU Zerun, YAN Guozheng, WANG Zhiwu, HUA Fangfang, YAO Shengjian, DING Zifan 2020, 54 (8):  813-819.  doi: 10.16183/j.cnki.jsjtu.2019.188 Abstract ( 902 )   HTML ( 8 )   PDF (10194KB) ( 345 )   Save The puborectalis-like artificial anal sphincter system (PAAS) uses transuctaneous energy transmission (TET) to charge lithium batteries integrated within the charging module. Therefore, the system can work stably during in-vivo experiments for a long period of time. Massive in-vivo experiments show that the large amount of heat generated in the wireless charging process is unfavorable to the biological safety of the living tissue near the charging module after PAAS implantation, so it is necessary to reasonably plan the wireless charging process. In this paper, by analyzing the heat conduction relationship of the internal components of the charging module, the internal thermal resistance model of the charging module is established, verified, and modified by in-vitro experiments. The modified model can reliably describe the temperature changes of the living tissue during charging. Based on the modified model, this paper formulates the single maximum continuous wireless charging time during the in-vivo experiment, thus improving the biological safety of PAAS during in-vivo experiments, and then prolonging the implantation time of PAAS. Figures and Tables | References | Related Articles | Metrics

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Evaluation of Tunnel Collapse Susceptibility Based on T-S Fuzzy Fault Tree and Bayesian Network CHEN Wu, WANG Hao, ZHANG Guohua, WANG Chengtang, ZHONG Guoqiang 2020, 54 (8):  820-830.  doi: 10.16183/j.cnki.jsjtu.2020.99.011 Abstract ( 1099 )   HTML ( 12 )   PDF (1496KB) ( 505 )   Save Collapse is one of the common disasters in the process of drilling and blasting tunnel construction. In order to effectively prevent the collapse accident and provide decision-making basis for safety risk analysis and management of tunnel construction, the T-S fuzzy fault tree and Bayesian network were combined, and an evaluation method based on both of them was proposed to calculate tunnel collapse possibility. According to the transformation of T-S fuzzy fault tree to Bayesian network, the Bayesian network model and conditional probability table were determined. In addition, fuzzy number and fuzzy subset were used to describe the fault state and probability of nodes respectively, and the bidirectional reasoning algorithm of Bayesian network was used to calculate. This method can use two different forward inferences to calculate the possibility of tunnel collapse, including the fuzzy subset of root node fault probability and the actual fault state in construction. At the same time, it can check the fault according to the result of importance analysis of root nodes, and can calculate the posterior probability of fault diagnosis of root nodes by back inference. Finally, the application of two engineering examples shows that the method can scientifically evaluate the possibility of tunnel collapse and determine key risk factors. This method can be used as a decision-making tool for tunnel construction safety assurance and management. Figures and Tables | References | Related Articles | Metrics

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Test and Numerical Study of Propeller Cavitation Induced Fluctuating Pressure of Twin-Propeller Ship XU Ye, XIONG Ying, HUANG Zheng 2020, 54 (8):  831-838.  doi: 10.16183/j.cnki.jsjtu.2019.069 Abstract ( 1139 )   HTML ( 11 )   PDF (6908KB) ( 303 )   Save To study propeller fluctuating pressure characteristic of highspeed twin-propeller ship in cavitation condition, a propeller open water test is conducted in deep water towing tank, while propeller after hull performance, fluctuating pressure measurement, and cavitation observation tests are conducted in a large circulating water channel with a complete ship model. The test results show that the maximum amplitude of fluctuating pressure increases with propeller speed, and unstable sheet cavitation leads to the increase in higher order components of fluctuating pressure. With the development of cavitation, the location of the maximum amplitude of fluctuating pressure moves to the inside of the model until distribution of fluctuating pressure keeps constant when the propeller reaches a certain speed. A computational fluid dynamics (CFD) numerical method to evaluate fluctuating pressure and cavitation of propeller is established using the shear stress transport (SST) k-ω model and the VOF method. The comparison of numerical and test results illustrates that the numerical results of fluctuating pressure have a good agreement with test results in non-cavitation and high rotation speed conditions, but the numerical values calculated are larger due to imprecise simulation of unstable sheet cavitation. There exists a large error in the numerical results of fluctuating pressure on the inside of the model which results from the attenuation of the value calculated and the phase difference of the two propellers in the test. Figures and Tables | References | Related Articles | Metrics

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Time-Resolved PIV Measurements and Numerical Study of Water Entry of a Wedge SHE Wenxuan, GUO Chunyu, ZHOU Guangli, WU Tiecheng, XU Peng 2020, 54 (8):  839-848.  doi: 10.16183/j.cnki.jsjtu.2019.065 Abstract ( 951 )   HTML ( 10 )   PDF (16786KB) ( 347 )   Save In order to study the wedge water entry problem and the feasibility of indirect evaluation of the slamming pressure based on particle image velocimetry (PIV), tests were conducted on the water entry of wedges at different deadrise angles using time-resolved PIV (TR-PIV). A numerical simulation was performed, and the transient pressure was reconstructed based on the PIV results. The motion response and flow field structure in the process of entering the water were analyzed in detail, and the accuracy and applicability of the pressure reconstruction scheme based TR-PIV were discussed. The results show that a good agreement is observed in TR-PIV measurements of the water entry and the numerical results. For different grid spacings and time steps, the pressure reconstruction scheme always has a good accuracy. The results of the slamming pressure field reconstruction of the wedges at different deadrise angles based on TR-PIV agree well with the numerical results, so do the evaluation results of the slamming load. Figures and Tables | References | Related Articles | Metrics

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Finite-Time Observer Design for Dynamic Positioning Assisted Mooring Positioning Ship XIA Guoqing, LIU Caiyun, CHEN Xinghua 2020, 54 (8):  849-855.  doi: 10.16183/j.cnki.jsjtu.2019.084 Abstract ( 872 )   HTML ( 7 )   PDF (882KB) ( 295 )   Save In response to the problem of unmeasurable velocity and uncertain external disturbances of the dynamic positioning assisted mooring positioning (DPM) system of the ship, a finite-time observer based on the traditional state observer to estimate the velocity and external disturbances is proposed. The unmodelled dynamic items in the system are considered in the modelling process of the ship. Based on the dynamics model, the mathematical expression of the finite-time observer is given. It is proved that the proposed finite-time observer is semi-global finite-time stable by using matrix inequality, homogeneous, and the Lyapunov stability theory. The observer is simulated and compared with the traditional state observer in order to justify that the proposed finite-time observer has a faster convergence and a better disturbance rejection. Figures and Tables | References | Related Articles | Metrics

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Simulation Study of Effect of Ejection Ratio on Combustion of a Stirling Engine Fueled with Biodiesel WANG Lintao, SUN Chunhua, LIN Zhimin, YU Xiangyu, QIAO Xinqi, YUAN Xiong, WANG Jigang 2020, 54 (8):  856-865.  doi: 10.16183/j.cnki.jsjtu.2019.066 Abstract ( 1007 )   HTML ( 5 )   PDF (3119KB) ( 367 )   Save A skeleton reaction mechanism of biodiesel was constructed by using the decoupling method, and a numerical calculation model of spray and combustion for a Stirling engine was established. The combustion characteristics of the Stirling engine fueled with biodiesel and petro-diesel respectively were compared, and the influence of ejection ratio on the temperature, speed, and composition field of biodiesel was also given. The results show that the simplified mechanism of biodiesel, Bio-37, can effectively reduce the reaction step to less than 100 under the premise of a better prediction of the high temperature ignition characteristics. Compared with petro-diesel, the oxygen characteristic of biodiesel is fully developed in the Stirlirg engine, when fueled with biodiesel. The flow fields of combustion temperatures and velocity are more uniform, the temperature of the flame baffle is lower, and the safety of the equipment is improved. With the increase in ejection ratio, the maximum temperature in the combustion chamber can be reduced, while the uniformity of temperature distribution can be improved, the temperature and flow intensity near the heat exchanger can be increased, and the thermal efficiency can be improved owning to the enhancement of heat and mass transfer. An increase in ejection ratio can also reduce the heat load of flame baffle and improve the reliability of Stirling engine. Figures and Tables | References | Related Articles | Metrics

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Equation for Soil Shrinkage Curve of Clay Considering Soil-Water Adsorption Effect CHEN Pan, XIANG Rui, WEI Xiaoqi, WEI Changfu, WANG Jili 2020, 54 (8):  866-872.  doi: 10.16183/j.cnki.jsjtu.2019.106 Abstract ( 961 )   HTML ( 9 )   PDF (1022KB) ( 290 )   Save Soil shrinkage occurs with the decrease of water content in soils under dry conditions, which has a great influence on soil cracking, bearing capacity, and slope stability. Hence, it is important to predict soil shrinkage effectively under the change of water content in soils. A novel mathematical equation is proposed for describing the soil shrinkage behavior within the full water content range considering the soil-water adsorption effect. The proposed equation can be used to characterize the soil shrinkage behavior of structural and non-structural clayey soils under dry conditions. An additional parameter is introduced into the proposed equation for characterizing the slope of soil shrinkage in low water content ranges, in which the effect of soil-water adsorption is considered. Only one equation is needed to predict the complete shrinkage behavior from saturated to zero water content conditions, especially for describing the volume change of soils under low water content. The proposed equation has been validated by comparing the results between the predicted curves using the proposed model and the measured data in literatures. Comparing with existing equations for soil shrinkage curve, the results show that the proposed equation can describe the non-zero shrinkage and non-zero shrinkage slope behaviors very well under low water content conditions. Furthermore, the results show that the soil-water adsorption effect is important and necessary for prediction of soil shrinkage behavior under low water content conditions. Figures and Tables | References | Related Articles | Metrics

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Test and Analysis of Deformation Characteristics of Deep Foundation Pit in Residual Soil Under Rainfall XIAO Zhaoyun, LI Mingguang, WANG Dafa, CHEN Jinjian 2020, 54 (8):  873-880.  doi: 10.16183/j.cnki.jsjtu.2019.012 Abstract ( 797 )   HTML ( 9 )   PDF (7435KB) ( 480 )   Save Residual soil has a poor water stability, whose strength varies with the changes of saturation and deformation. To study the deformation response of foundation pit in deep residual soil affected by rainfall, the deformation of retaining pile and ground surface settlement outside the pit was monitored based on a deep residual soil foundation pit project in Xiamen. Combining the excavation steps with rainfall data, the influence of the strength weakness of residual soil caused by rainfall on the deformation of retaining piles and soil was discussed. The results show that the deformation of retaining piles and soil settlements remains stable during rainfall, and increases slowly in the stage of drainage. However, as the excavation continues after drainage, the deformation increases significantly. The maximum lateral deformation affected by rainfall is about 1.5 times of that without rainfall. The influence range of the ground surface settlement on excavation depth increases from 1.5 to 2.5 times due to rainfall. The results have a certain reference significance for the engineering application of residual soil foundation pit affected by rainfall. Figures and Tables | References | Related Articles | Metrics