Table of Content

28 March 2020, Volume 54 Issue 3 Previous Issue    Next Issue

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Depositional Environment and Over-Consolidation of the 8th Layer Clay in Shanghai LIU Libin, LAN Lixin, LI Mingguang, YE Guanlin 2020, 54 (3):  221-226.  doi: 10.16183/j.cnki.jsjtu.2020.03.001 Abstract ( 1091 )   PDF (806KB) ( 388 )   Save With the increasing congestion of underground space facilities, the depths of underground structures are increasing. And the study of deep soils is becoming more and more important. The sedimentary environment of deep soil (the 6th—9th layer clays) in Shanghai was analyzed by studying the sea level and atmospheric temperature changes in the East China Sea since the late Pleistocene. The sedimentary environments of the 6th to the 9th layer clays were found to be lakes, rivers-marinas, lakes and rivers-marinas, rivers. By using the Becker energy method to analyze the results of the high-pressure consolidation test, the over-consolidation ratio of the 8th layer clay was about 3.0. Through the triaxial consolidated undrain test, it was found that the pore pressure coefficient while soil sample failure was negative, showing the characteristics of strong over-consolidated soil. From the perspective of stress and non-stress, the causes of over-consolidation of the 8th layer clay were analyzed. With the groundwater level decreasing, the pore water in the soil dissipated. And the increase of effective stress in the soil was the cause of stress. The long-term secondary consolidation and cementation were the reasons of non-stress. References | Related Articles | Metrics

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Post-Breakage Strength of Laminated Glass Panel Cracked by Impact LIU Xinwei, YANG Jian, WANG Xinger, LIU Qiang 2020, 54 (3):  227-238.  doi: 10.16183/j.cnki.jsjtu.2020.03.002 Abstract ( 978 )   PDF (15467KB) ( 210 )   Save In this paper, different glass configurations using annealed glass (ANG) and fully tempered glass (FTG) as well as different interlayer combinations were introduced. Fifteen laminated glass (LG) panels in five groups cracked by impact were statically tested. Through analyzing the load-displacement relationship, the effects due to the crack pattern and interlayer type on the post-breakage performance were examined. The results show that the crack pattern of inner glass dominates the load bearing mechanism of LG. Compared to FTG, ANG can produce beneficial crack pattern and generate better load transferring path to retain greater strength. Compared to inner FTG, an increase of 46.5% in post-breakage strength can be found when using inner ANG. The static resistance of LG using hybrid SentryGlas@Plus (SGP)/polyvinyl butyral（PVB）is only 37% of that uses double SGP interlayers. However, the LG using double SGP interlayers has the failure mode of central penetration which presents brittle characteristics and is unfavorable in engineering practice. The LG using hybrid SGP/PVB shows greater ductility while the interlayer can fully function. References | Related Articles | Metrics

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Tests on the Influence on Electro-Osmotic Effect of Drainage by Adding Humic Acid Buffer Solution to the Cathode Region ZHOU Jian, GAN Qiyun, QIAN Wei, CAO Yun 2020, 54 (3):  239-246.  doi: 10.16183/j.cnki.jsjtu.2020.03.003 Abstract ( 899 )   PDF (1213KB) ( 223 )   Save According to the technology of electric restoration for heavy metal contaminated soil, this paper adjusted the pH value by adding humic acid buffer solution to the cathode region to improve the electro-osmotic drainage effect, and compared the final drainage effect from multiple aspects. The relation between drainage rate and ζ potential was deduced. The results were explained at the points of ζ potential, metal ion and fulvic acid’s complexation to metal ion. The results show that adding humic acid to cathode region cannot increase the drainage accumulation, and soft clay with high humic acid concentration is not suitable for large-scale electro-osmotic drainage and consolidation. References | Related Articles | Metrics

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Parallel Machine Scheduling Problem Considering Machine Reliability and Energy Consumption XU Xianyang，CHEN Lu 2020, 54 (3):  247-255.  doi: 10.16183/j.cnki.jsjtu.2020.03.004 Abstract ( 890 )   PDF (1118KB) ( 295 )   Save Reliability is formulated in parallel machine energy-efficient schedluing problem, to consider the impact of machine condition on processing energy, and to reduce energy consumption effectively in production workshop. A mathematical programming model is developed with the objective to minimize both tardiness cost and energy cost. An ant colony algorithm is designed to solve the problem. A new heuristic factor is proposed to design the search process. And local search mechanisms are embedeed in the algorithm to improve the quality of the solution. The effectiveness and efficiency of the algorithm are verified by computational experiments. The impact of reliability dispersion and due date tightness on scheduling decisions are evaluated through sensitivity analyses, which provide useful support for real shop scheduling. References | Related Articles | Metrics

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Life Cycle Assessment of Marine Power System’s Green Design WANG Ruichang，CHEN Zhihua，MING Xinguo 2020, 54 (3):  256-264.  doi: 10.16183/j.cnki.jsjtu.2020.03.005 Abstract ( 807 )   PDF (1040KB) ( 270 )   Save In order to reduce the pollution of ships to the environment and realize green design of the marine power system, this paper establishes the boundary of system and presents a life cycle assessment scheme of this system. Taking into account the interaction between evaluation indicators, we utilize Delphi method and analytic network process to determine the weight for each indicator of marine power system by establishing an evaluation index super-matrix and finding its limit. The methods proposed in the paper are verified by analyzing a current marine power system and explaining different green design schemes, and they provide a new approach to green design assessment of the marine power system. References | Related Articles | Metrics

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Rotating Instability Characteristics in Compressor with Different Tip Clearances LAI Shengzhi，WU Yadong，TIAN Jie，OUYANG Hua 2020, 54 (3):  265-276.  doi: 10.16183/j.cnki.jsjtu.2020.03.006 Abstract ( 1007 )   PDF (11604KB) ( 304 )   Save Rotating instability (RI) characteristics of a single stage low speed compressor are analyzed by full channel numerical calculation method. Variations and the reasons of frequency characteristics, modes characteristics and flow characteristics of RI under four different tip clearances are investigated. The coherence analysis method is used to obtain the coherent function and the mutual power spectrum of the pressure signal at the same angle in the adjacent blade channel, which show the propagation characteristics of the channel vortex structure with flow in the circumferential direction. The circumferential modal characteristics of RI, the pulsating and rotating characteristics of channel vortex structures affecting RI as well as its relationship in absolute and relative coordinate systems are obtained by spatial mode decomposition and rotation source mechanism analysis. Results show that with the decrease of tip clearance, the flow intensity of tip clearance decreases, the intensity of RI gradually decreases, and the order of main modes increases. References | Related Articles | Metrics

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Numerical Simulation and Tests on Inflation of an Airship Envelope Model with Cutting Pattern Effects LI Yi,CHEN Wujun,GAO Chengjun,WANG Xueming,HE Wei 2020, 54 (3):  277-284.  doi: 10.16183/j.cnki.jsjtu.2020.03.007 Abstract ( 875 )   PDF (8877KB) ( 210 )   Save In order to study the structural mechanical properties of the airship, a reduced scale airship model considering the cutting pattern effect was established. The biaxial tensile test of woven fabrics was carried out firstly. According to a series of biaxial tensile tests, the stress response surface of the mechanical parameters of envelop material was fitted and a material model subroutine was prepared. Based on the simulation of the cutting process with Abaqus, the finite element model of the initial configuration was established and the inflation process of the model was numerically simulated. Finally, the reduced scale airship model was designed and fabricated to perform the inflation test, and the deformation characteristics of the envelop under different internal pressures were measured. Results showed that there was an obvious difference between the initial configuration of the airship considering cutting effect and the ideal rotory model. The error of the gore’s maximum deformation of the cutting model was within 12% and decreased with the increase of the internal pressure. The cutting effect had a non-negligible role in the airship fine-modeling analysis. References | Related Articles | Metrics

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Effects of Submerged and Emergent Rigid Short Vegetation Canopies on Gravity Current Dynamics XIONG Jie,YUAN Yeping,LIN Yingdian 2020, 54 (3):  285-294.  doi: 10.16183/j.cnki.jsjtu.2020.03.008 Abstract ( 805 )   PDF (7663KB) ( 221 )   Save A series of lock-exchange experiments are carried out to study effects of vegetation density and height for short vegetation canopies on gravity current motions. A high-speed camera is applied to acquire the evolution process of the gravity currents, and a particle image velocimetry system is used to investigate the microstructures of gravity currents. Experimental results show that when the gravity current flows through short vegetation canopies, the gravity currents profile will be in the shape of classic ellipse or a well-defined triangle. Movement process is divided into slumping phase and self-similar phase. Furthermore, vegetation canopies can significantly promote the transition of gravity currents from slumping phase into self-similar phase, but cannot influence the current front velocity during the slumping phase. As the non-dimensional vegetation height (the ratio of vegetation height to water depth) is 0.21 with the vegetation density being 18.0%, the gravity current flows along the upper edge of vegetation and within vegetation at the same time. Since the current density on the top of vegetation is larger than that within vegetation, the Rayleigh-Taylor instability occurs. In addition, the entrainment coefficient of gravity current within vegetation decreases as the current moves further, and it is smaller than that without vegetation. When the density current moves into the submerged vegetation, some current climbs on the top of the vegetation where a new “bottom boundary” for gravity current is formed and negative vorticity is produced. In the upper boundary of the current, the current keeps mixing with the ambient fluid and induces the positive vorticity. The results also suggest that vegetation reduces the current speed as well as the strength of positive vorticity, and the vegetation density is proportional to the reduction degree of the positive vorticity. References | Related Articles | Metrics

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Collision Avoidance Strategy for Autonomous Underwater Vehicle Based on Null-Space-Based Behavioral Approach PANG Shikun,LIANG Xiaofeng,LI Yinghui,YI Hong 2020, 54 (3):  295-304.  doi: 10.16183/j.cnki.jsjtu.2020.03.009 Abstract ( 1274 )   PDF (1569KB) ( 518 )   Save An autonomous underwater vehicle (AUV) obstacle avoidance strategy based on null-space-based behavioral (NSB) approach is designed, aiming at solving dynamic or static obstacle avoidance problem the AUV will encounter while moving to the target in complex underwater environment. Firstly, the AUV overall task moving to the target is decomposed into different subtasks, and the obstacle avoidance subtask is set as the highest priority. As for multi-task control targets, the low-level task vector is projected to the null space of the higher task vector, and the integrated task output is used as the final output function. The low-level task is partially or completely completed while completing the higher task, thereby the mutual conflict between different level targets can be avoided in this way. In order to study the obstacle avoidance strategy for static and dynamic obstacles, the corresponding task functions are designed in accordance with different subtask priorities. The comprehensive output function of AUV motion is deduced and established to ensure that it can avoid different types of obstacles effectively in the process of heading to the target point. The simulation results demonstrate the effectiveness and the feasibility of the proposed method, which could achieve an expected obstacle avoidance effect in complex underwater obstacle environments. References | Related Articles | Metrics

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Intelligent Vehicles Formation Control Based on Artificial Potential Field and Virtual Leader WANG Shufeng,ZHANG Junxin,ZHANG Junyou 2020, 54 (3):  305-311.  doi: 10.16183/j.cnki.jsjtu.2020.03.010 Abstract ( 1336 )   PDF (1118KB) ( 506 )   Save In order to improve the traffic efficiency and the road safety, this paper studied the formation control of intelligence vehicles in highway environment. The combination of the artificial potential field and the virtual leader method was adopted to control vehicles. Taking the ideal road formation as the goal, the elliptical virtual force scope of virtual leader was proposed and the formation unit model was established under the condition of considering the longitudinal and horizontal safety distance of formation and the highway environment security constraints. Then, the stability of the unit model was proved by Lyapunov function. In order to improve the formation flexibility and eliminate the position errors of vehicles, the decomposition-iterative idea was introduced to the multi-vehicle formation control, and the vertical and horizontal iterations of formation units were set up according to road conditions. Taking the six-vehicle formation as the simulation verification example, the result of simulation shows that the formation model can stably and effectively control vehicles to achieve the ideal highway formation. References | Related Articles | Metrics

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Accurate Dynamics Modeling and Roll Stability of Tank Vehicle REN Yuanyuan,LI Xiansheng,ZHENG Xuelian,WANG Jie 2020, 54 (3):  312-321.  doi: 10.16183/j.cnki.jsjtu.2020.03.011 Abstract ( 869 )   PDF (1457KB) ( 360 )   Save Equivalent trammel pendulum model is established to describe lateral liquid sloshing in common tanks, and its dynamical equation under non-inertial coordinate system is then derived. The accurate dynamic model of tank vehicle is established on the basis of vehicle force analysis. Thereafter, the model of tanker vehicle is established in TruckSim, and its dynamic response is analyzed. The results show that compared to normal trucks, tankers have slight understeer characteristics, and their turning radius decreases about 3%-7%. At the same time, tankers have much greater lateral load transfer, and their critical speed decreases more than 30% when liquid fill level is lower than 0.7. The ratio of pendulum mass to tanker mass is the main factor that alleviates vehicle roll stability, and it is determined mainly by liquid fill percentage and tank shape. Tank vehicle has quite bad stability when liquid fill percentage is 0.4-0.7, which should be avoided as much as possible. When liquid fill level is not lower than 0.8 most of the time, tankers with elliptical cross section are recommended, otherwise cylinder tank is a better choice. Liquid viscous has a great influence on vehicle transient dynamics. With its increase, vehicle steady time and its overshoot is greatly alleviated, and the function would be more obvious when tank vehicle is flatter. References | Related Articles | Metrics

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Early Warning Method for Tardiness Precaution Oriented to Rocket Final Assembly Process ZHANG Jie,ZHAO Xinming,ZHANG Peng,SHENG Xia,CHAO Xiaona,TIAN Fengxiang 2020, 54 (3):  322-330.  doi: 10.16183/j.cnki.jsjtu.2020.03.012 Abstract ( 1043 )   PDF (1507KB) ( 365 )   Save To prevent the overdue risks caused by randomness and dynamic events during rocket final assembly process, an early warning method for tardiness precaution is proposed to ensure in-time delivery. The method includes three steps: indicator monitoring, warning sign recognition and warning level prognostication. The inputs are quantized indicators which are elaborately designed by analyzing key factors and their mechanisms influencing the cycle time. Its main task is to monitor the progress of the rocket final assembly. An imbalanced learning algorithm considering the unbalanced nature of the data under different warning levels is utilized to achieve warning sign recognition. By considering both the tardiness of the job and the difficulty in adjustment during sample collecting, the warning level of sample is designed to realize warning level prognostication. The effectiveness and superiority of the proposed model are proven by applying the model to practical production data collected from some aerospace equipment company in Shanghai. References | Related Articles | Metrics