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Time-Varying Delay and Quantization Error LI Bin (李 斌), WAN Yi-ming (万一鸣), YE Hao (叶 昊) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 513-518.   DOI: 10.1007/s12204-011-1181-9 Abstract （1954）      PDF（pc） （303KB）（3081）       Knowledge map    Save Abstract:  Problems related to fault detection of networked control systems (NCSs) with both uncertain time-varying delay and quantization error are studied in this paper. A novel model with the form of polytopic uncertainty is given to represent the influences of both the time-varying delay and the quantization error, and then the reference model based method is used to design the residual generator that is robust to both unknown network-induced delay and unknown inputs. A numerical example is also given to illustrate the merits of the presented method. The proposed method can be regarded as an extension of the authors' former work, which can only deal with time-varying delay. Reference | Related Articles | Metrics | Comments（0）

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Electric vehicle charging situation awareness for charging station ultra-short-term load forecast SHI Yiwei1 (史一炜), LIU Zeyu1 (刘泽宇), FENG Donghan1∗ (冯冬涵), ZHOU Yun1∗ (周 云), ZHANG Kaiyu2 (张开宇), LI Hengjie3 (李恒杰) J Shanghai Jiaotong Univ Sci    2023, 28 (1): 28-38.   DOI: 10.1007/s12204-023-2566-2 Abstract （305）      PDF（pc） （1518KB）（1219）       Knowledge map    Save Electric vehicles (EVs) are expected to be key nodes connecting transportation–electricity–communication networks. Advanced automotive electronics technologies enhance EVs’ perception, computing, and communication capacity, which in turn can boost the operational efficiency of intelligent transportation systems (ITSs). EVs couple the ITS to the power system, providing a promising solution to charging congestion and transformer overload via navigation and forecasting approaches. This study proposes a privacy-preserving EV charging situation awareness framework and method to forecast the ultra-short-term load of charging stations. The proposed method only relies on public information from commercial service providers. In the case study, data are powered by the Baidu LBS cloud and EV-SGCC platform, and the experiment is conducted within an area of Pudong New District in Shanghai. Based on the results, the charging load of charging stations can be adequately forecasted more than 1 min ahead with low communication and computing power requirements. This research provides the basis for further studies on operation optimization and electricity market transaction of charging stations. Reference | Related Articles | Metrics | Comments（0）

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D2EA: Depict the Epidemic Picture of COVID-19 LIU Chenzhengyi (刘陈正轶), ZHAO Jingwei (赵经纬), LIU Guohang (刘国航), GAO Yuanning (高远宁), GAO Xiaofeng (高晓沨) J Shanghai Jiaotong Univ Sci    2020, 25 (2): 165-176.   DOI: 10.1007/s12204-020-2170-7 Abstract （534）      PDF（pc） （748KB）（923）       Knowledge map    Save The outbreak of coronavirus disease 2019 (COVID-19) has aroused a global alert. To release social panic and guide future schedules, this article proposes a novel mathematical model, the Delay Differential Epidemic Analyzer (D2EA), to analyze the dynamics of epidemic and forecast its future trends. Based on the traditional Susceptible-Exposed-Infectious-Recovered (SEIR) model, the D2EA model innovatively introduces a set of quarantine states and applies both ordinary differential equations and delay differential equations to describe the transition between two states. Potential variations of practical factors are further considered to reveal the true epidemic picture. In the experiment part, we use the D2EA model to simulate the epidemic in Hubei Province. Fitting to the collected real data as non-linear optimization, the D2EA model forecasts that the accumulated confirmed infected cases in Hubei Province will reach the peak at the end of February and then steady down. We also evaluate the effectiveness of the quarantine measures and schedule the date to reopen Hubei Province. Reference | Related Articles | Metrics | Comments（0）

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Hybrid Process of Fabricating High-Quality Micro Wine-Glass Fused Silica Resonators XING Yaliang (邢亚亮), ZHANG Weiping* (张卫平), TANG Jian (唐健),SUN Dianjun (孙殿俊), LIU Zhaoyang (刘朝阳), OU Bin (欧斌) Journal of shanghai Jiaotong University (Science)    2017, 22 (3): 274-279.   DOI: 10.1007/s12204-017-1832-6 Abstract （917）            Knowledge map    Save A new hybrid method, which combines improved glass-blown technology with wet etching, is reported to fabricate micro wine-glass resonators with high-quality fused silica. The optimum placement is compared to achieve the resonators with good shell shape. The typical shell diameter is about 4mm and its thickness covers from dozens to hundreds of micrometers. The etching rates in corrosion solutions with different ratios and at different thicknesses of hemispherical shells are studied. We also conclude how to precisely control the thickness. The corrosion solutions with different ratios of HF solution to NH4F solution make the spherical shells rougher in different degrees. The best roughness is 0.581 nm in the 1 : 8 ratio corrosion solution while the original roughness is 0.537 nm. This fact shows that the resonator remains atomically smooth surface. Based on the glassblowing spherical fused silica structure, the thickness of the resonator is effectively controlled by buffered oxide etch (BOE) technology according to the measured etching rate. The measured resonant frequency of the hemispherical shell at ambient pressure and room temperature is 1.75 kHz of rocking mode which is close to the simulated frequency. Using such a low-cost hybrid approach, we can fabricate high-quality microscale resonators in batch. Reference | Related Articles | Metrics | Comments（0）

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Model Testing for Ship Hydroelasticity: A Review and Future Trends JIAO Jialong1,2 (焦甲龙), REN Huilong2 (任慧龙), CHEN Chaohe1* (陈超核) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 641-650.   DOI: 10.1007/s12204-017-1886-5 Abstract （806）            Knowledge map    Save Conducting model experiments is an effective and reliable way in the investigation of ship hydrodynamic and hydroelastic behaviors. A survey of model testing techniques for ship hydroelasticity and its prospect are presented in this paper. The research highlights with respect to ship hydroelasticity and key points in model testing are summarized at first. Then testing techniques including laboratory tank test and full-scale sea trial are reviewed, and both their advantages and disadvantages are analyzed comprehensively. Based on the conventional testing approaches, a state-of-the-art testing approach which includes performing tests using large-scale model at sea is proposed. Furthermore, recommendations towards the further development of ship hydroelasticity tests are forecasted and discussed. Reference | Related Articles | Metrics | Comments（0）

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Review on Corrosion Characteristics of Porous Titanium Alloys Fabricated by Additive Manufacturing GAI Xin, (盖欣), BAI Yun (白芸), LI Shujun (李述军), WANG Liao (王燎), AI Songtao (艾松涛), HAO Yulin (郝玉琳), YANG Rui (杨锐), DAI Kerong (戴尅戎) J Shanghai Jiaotong Univ Sci    2021, 26 (3): 416-430.   DOI: 10.1007/s12204-021-2314-4 Abstract （326）      PDF（pc） （1891KB）（732）       Knowledge map    Save Porous titanium and its alloys have been considered as promising implants owing to their low elastic  modulus and capability to provide channels for bone growth. Currently, additive manufacturing (3D printing)  techniques have been successfully applied to produce porous titanium alloys owing to the advantages of controllable  and precise fabrication. Considering the safety aspect, an understanding of corrosion in porous titanium alloys  and the corresponding mechanisms is important for their long-term application in the human body. In this  paper, the recent progress in improving the corrosion properties of porous titanium alloys fabricated via 3D  printing techniques is reviewed. The effects of pore type, porosity, electrolyte, and modification of the material  on the corrosion properties of porous titanium alloys are introduced and discussed. In addition, the limitations of  traditional methods for measuring the corrosion performance of porous titanium alloys were analysed. Perspectives  for evaluating and improving the corrosion performance of porous titanium alloys using new methods are provided.  Reference | Related Articles | Metrics | Comments（0）

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CT Reconstruction with Priori MRI Images Through Multi-Group Datasets Expansion WANG Qihui (王齐辉), XI Yan (奚岩), CHEN Yi (陈毅),ZHANG Weikang (张伟康), ZHAO Jun* (赵俊) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 756-762.   DOI: 10.1007/s12204-017-1897-2 Abstract （771）            Knowledge map    Save Computed tomography (CT) reconstruction with a well-registered priori magnetic resonance imaging (MRI) image can improve reconstruction results with low-dose CT, because well-registered CT and MRI images have similar structures. However, in clinical settings, the CT image of patients does not always match the priori MRI image because of breathing and movement of patients during CT scanning. To improve the image quality in this case, multi-group datasets expansion is proposed in this paper. In our method, multi-group CT-MRI datasets are formed by expanding CT-MRI datasets. These expanded datasets can also be used by most existing CT-MRI algorithms and improve the reconstructed image quality when the CT image of a patient is not registered with the priori MRI image. In the experiments, we evaluate the performance of the algorithm by using multi-group CT-MRI datasets in several unregistered situations. Experiments show that when the CT and priori MRI images are not registered, the reconstruction results of using multi-group dataset expansion are better than those obtained without using the expansion. Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Performance of Combined Cambered-Type Wave Absorbing Beach LI Jun* (李俊), YANG Jianmin (杨建民), PENG Tao (彭涛) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 651-656.   DOI: 10.1007/s12204-017-1887-4 Abstract （777）            Knowledge map    Save Wave simulation performance and its quality are key factors to reflect the overall capacity and level of an ocean engineering basin. They include wave simulating and absorbing capacity of reflected waves. In order to reduce the influence of reflected waves, various wave absorbing devices are equipped in ocean engineering basins across the world. The experimental investigation into the performance of combined cambered-type wave absorbing beach (CCTWAB) with damping bars equipped in Deepwater Offshore Basin is conducted. The experiment adopts the two-point method. The reflection coefficients are calculated by the method, in which the incident and reflected waves can be separated from the physically simulated composite waves with different periods and wave heights in the time domain. The experimental results indicate that in the range of normal wave heights and periods for model tests, the CCTWAB with damping bars is excellent in eliminating the reflected waves. Reference | Related Articles | Metrics | Comments（0）

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Minimum Resistance Ship Hull Uncertainty Optimization Design Based on Simulation-Based Design Method HOU Yuanhang* (候远杭), YOU Yuan (游园), LIANG Xiao (梁霄) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 657-663.   DOI: 10.1007/s12204-017-1882-9 Abstract （706）            Knowledge map    Save In the ship hull optimization design based on simulation-based design (SBD) technology, low precision of the approximate model leads to an uncertainty form of optimization model. In order to enable the approximate model with finite precision to maximize the effectiveness, uncertainty optimization method is introduced here. Wave resistance coefficient approximation model, built by back propagation (BP) neural network, is represented as a form of interval. Afterwards, a minimum resistance optimization model is established with the design space constituted by principal dimensions and ship form coefficients. Double-level nested optimization architecture is proposed: for outer layer, improved particle swarm optimization (IPSO) algorithm with learning factor improvement strategy is used to generate design variables, and for inner layer, modified very fast simulated annealing (MVFSA) algorithm is used to solve the objective function interval with uncertainty region. Cases calculation proves the effectiveness and superiority of uncertainty optimization method for ship hull SBD optimization design, thus providing a good way for finding optimal designs. Reference | Related Articles | Metrics | Comments（0）

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Optimal Allocation of Fleet’s Spare Parts for System Reliability WANG Hongdonga (王鸿东), LI Danb* (李丹), YI Honga (易宏) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 664-671.   DOI: 10.1007/s12204-017-1888-3 Abstract （766）            Knowledge map    Save Allocation of fleet’s spare parts is rarely studied due to its complexity. However, this task is extremely important because the warship’s service level highly relies on the maintenance logistics’ level. In this study, the readiness ratio is proposed as a critical index in measuring the system’s reliability. A well-established mathematical model adopting the optimization method of spare part allocation is also introduced. The objective is to minimize the number of each spare part while satisfying the fleet’s system reliability. The fault tree analysis (FTA) is applied to analyze the system’s failure logic and stratify the units on ship. As a result, the strategy of spare part sharing can be introduced in detail. The solution algorithm is developed, and the simulation experiments to obtain the key parameters are conducted. The proposed model and algorithm are applied to an actual fleet of two warships, and results show that the method above is feasible and can be directly applied into practice. Reference | Related Articles | Metrics | Comments（0）

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Uncertainty Analysis of Value for Money Assessment for Public-Private Partnership Projects LIANG Qingxue (梁晴雪), HU Hao* (胡昊) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 672-681.   DOI: 10.1007/s12204-017-1889-2 Abstract （845）            Knowledge map    Save In recent years, private sectors are encouraged to take an active part in franchising of urban infrastructure investments and operations, which promotes the rapid development of public-private partnership (PPP) in infrastructure and public service supply. Value for money (VFM) assessment has been officially proposed to provide a reference for selection of projects planning to adopt PPP. Based on the bottlenecks of VFM application in China and the uncertainties for urban infrastructure PPP projects, a discounted cash flow (DCF) model is established for VFM of infrastructure PPP projects. Then, a Monte Carlo simulation model is established on the basis of uncertainty factors for VFM. Through the analysis of Huai’an trams PPP project, coping strategies of uncertainties for VFM are put forward. Findings of the research may propel the establishment of a complete VFM evaluation system for PPP projects. Key instructional functions of VFM during the process of decision-making can be brought into full play and PPP may develop orderly. Reference | Related Articles | Metrics | Comments（0）

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Pedestrian Crosswalk Overflow Violation in China: Characteristics and Countermeasure CAO Ningbo (曹宁博), CHEN Yongheng* (陈永恒), QU Zhaowei (曲昭伟),ZHAO Liying (赵利英), BAI Qiaowen (白乔文), DENG Xiaolei (邓晓磊) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 688-696.   DOI: 10.1007/s12204-017-1891-8 Abstract （788）            Knowledge map    Save The phenomenon that pedestrians do not walk in the crosswalk during pedestrian green is defined as overflow violation, which is illegal but common. Broadly varying crossing positions at far-side cross-section may result in widely distributed conflict points with left-turning and right-turning vehicles, which may cause the occurrence of severe conflicts. This paper proposes a model to estimate the overflow pedestrians’ crossing positions at the far-side cross-section of signalized crosswalk, which enables us to better understand pedestrian overflow violation behavior and finally facilitate their safety. After analysis, the intersection geometry and destination are determined as the critical factors causing pedestrians to overflow. And then, Weibull distribution is employed to describe the stochastic characteristics of overflow pedestrians’ crossing position distribution at the far-side cross-section. A crossing position distribution model which takes the crosswalk length, width and distance between crosswalk and destination into account is developed. The established model is validated by comparing the observed pedestrian crossing positions with the estimated crossing positions. The validation results suggest that the established model is capable of being adopted to estimate the overflow pedestrians’ crossing positions at far-side cross-section. Based on the model, countermeasure for overflow violation can be put forward to prevent pedestrians from walking outside the crosswalk. Reference | Related Articles | Metrics | Comments（0）

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Application of Digital Image Correlation Method to In-Situ Dynamic Strain Measurement LIN Liexiong (林烈雄), LU Hao* (陆皓), XU Jijin (徐济进),CHEN Junmei (陈俊梅), YU Chun (余春) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 719-725.   DOI: 10.1007/s12204-017-1864-y Abstract （803）            Knowledge map    Save Application of digital image correlation (DIC) method to determination of in-situ dynamic strain is presented in this study. Firstly, an integrative software is programmed based on the DIC algorithms and pointwise least-squares fitting technique. Then, simulated speckle images are generated to study the computational accuracy of this software. The experimental setup and procedures for measuring in-situ dynamic strain through both DIC and strain gauge are proposed. The DIC results are close to those measured by strain gauge. This fact reveals that DIC is a practical and effective tool for in-situ dynamic strain measurement. Finally, the full-field in-situ dynamic strain of another specimen is measured by DIC, and the overall distribution of the strain in the measurement area is clearly shown. Reference | Related Articles | Metrics | Comments（0）

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Integration of Learning Algorithm on Fuzzy Min-Max Neural Networks HU Jing* (胡静), LUO Yiyuan (罗宜元) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 733-741.   DOI: 10.1007/s12204-017-1894-5 Abstract （941）            Knowledge map    Save An integrated fuzzy min-max neural network (IFMMNN) is developed to avoid the classification result influenced by the input sequence of training samples, and the learning algorithm can be used as pure clustering, pure classification, or a hybrid clustering classification. Three experiments are designed to realize the aim. The serial input of samples is changed to parallel input, and the fuzzy membership function is substituted by similarity matrix. The experimental results show its superiority in contrast with the original method proposed by Simpson. Reference | Related Articles | Metrics | Comments（0）

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Trade-off in Optimizing Energy Consumption and End User Quality of Experience in Radio Access Network XU Yuemei1* (徐月梅), WANG Zihou2 (王子厚), LI Yang3 (李杨), CAI Lianqiao1 (蔡连侨) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 742-751.   DOI: 10.1007/s12204-017-1895-4 Abstract （658）            Knowledge map    Save To reduce network access latency, network traffic volume and server load, caching capacity has been proposed as a component of evolved Node B (eNodeB) in the ratio access network (RAN). These eNodeB caches reduce transport energy consumption but lead to additional energy cost by equipping every eNodeB with caching capacity. Existing researches focus on how to minimize total energy consumption, but often ignore the trade-off between energy efficiency and end user quality of experience, which may lead to undesired network performance degradation. In this paper, for the first time, we build an energy model to formulate the problem of minimizing total energy consumption at eNodeB caches by taking a trade-off between energy efficiency and end user quality of experience. Through coordinating all the eNodeB caches in the same RAN, the proposed model can take a good balance between caching energy and transport energy consumption while also guarantee end user quality of experience. The experimental results demonstrate the effectiveness of the proposed model. Compared with the existing works, our proposal significantly reduces the energy consumption by approximately 17% while keeps superior end user quality of experience performance. Reference | Related Articles | Metrics | Comments（0）

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Optimal Inspection and Replacement Strategy for Systems Subject to Two Types of Failures with Adjustable Inspection Intervals MA Xiaoyang1* (马晓洋), WANG Wenbin1,2 (王文彬), LIU Xuejuan1 (刘学娟), PENG Rui1 (彭锐) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 752-755.   DOI: 10.1007/s12204-017-1896-3 Abstract （672）            Knowledge map    Save The inspection activities are often carried out to detect possible indication of failures in plant systems. This paper considers a single unit system subject to two types of failures, where one failure mode is the traditional 0-1 logic failure and the other failure mode is described by a two-stage failure process. Adjustable inspections are used to detect the defective stage of the latter. We assume that the inspection duration gets shorter and shorter with a constant ratio. At the same time, preventive replacement is used to avoid the possible failure due to the former failure mode. The renewal process of this system is analyzed and the expected long-run cost per unit time (ELRCUT) is derived. The optimal inspection period and the preventive replacement interval to minimize ELRCUT are studied. At last, a numerical example is presented to illustrate the proposed model. Reference | Related Articles | Metrics | Comments（0）

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Experimental Simulation on Dynamic Variation of the Permeability of High-Rank Coal Reservoirs HE Ye1,2* (何也), FU Xuehai1 (傅雪海), LIU Aihua3 (刘爱华) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 726-732.   DOI: 10.1007/s12204-017-1893-6 Abstract （563）            Knowledge map    Save In terms of the coal reservoir permeability of effective stress, coal matrix shrinkage and gas slippage, we conduct the tests of gas permeability under constant confining pressure and effective stress, as well as illustrate the cumulating method of permeability increment caused by the effects of gas slippage and coal matrix shrinkage. The results show that under the constant confining pressure, gas slippage affecting coal permeability changes to effective stress affecting it mainly. The change point increases with the increase of the confining pressure. The gas slippage effect leads to high permeability under low confining pressure, but coal matrix expansion results in the low value as confining and gas pressures increase. Combined with the drainage process of coalbed methane (CBM) well, the permeability is divided into four change stages based on the above analysis about the three effects, which can improve the change regulation understanding. Four stages are the downward phase under effective stress, the conversion phase of effective stress-coal matrix contraction effect (mainly based on effective stress), the rising stage of the effective stress-coal matrix contraction effect (mainly based on coal matrix contraction effect) and the rising phase of coal matrix contraction-slippage effect (mainly based on slippage effect). Permeability of coal reservoir during the process of drainage and production goes through four stages. Reference | Related Articles | Metrics | Comments（0）

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Microscopic Structure and Property of Double-Electrode Gas Metal Arc Welding of AZ31B Magnesium Alloy MA Guohong1* (马国红), SHEN Xu1 (沈旭), PING Qiwen1 (平齐文),NIE Jun1 (聂军), YE Jia2 (叶佳) Journal of shanghai Jiaotong University (Science)    2017, 22 (3): 286-290.   DOI: 10.1007/s12204-017-1834-4 Abstract （832）            Knowledge map    Save This paper focuses on the research on double-electrode gas metal arc welding (DE-GMAW) of AZ31B magnesium alloy sheet with 2mm thickness. During the welding process, stable hybrid arc of metal inert gas (MIG) and tungsten inert gas (TIG) is employed as welding heat source. Optical and electron microscopes are used to observe the microstructures of the weld joint. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) are employed to identify the components in fusion zone. Microhardness is also tested. When the MIG current is 80A, the perfect weld joint is obtained, though figures of fish scales are observed in all joints in the research. The fusion zone is formed by dendrites, where β-Mg17(Al, Zn)12 is dispersed. The hardness in fusion zone and heat affected zone (HAZ) is lower than that in base metal (BM). The average Vickers hardness of fusion zone and HAZ is about 58 and 56 respectively, while the Vickers hardness of BM is about 63. Reference | Related Articles | Metrics | Comments（0）

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Microstructure Evolution During Remelting of High Solid Fraction ZL101 Alloy LUO Shuai (罗帅), YU Huping* (于沪平), QIU Haiyuan (邱海渊), SHEN Yu (申昱) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 712-718.   DOI: 10.1007/s12204-017-1885-6 Abstract （745）            Knowledge map    Save This work deals with the reheating process for semi-solid thixoforming of ZL101 (AlSi7Mg) alloy. The semi-solid state can decrease the viscosity and the resistance while sheared because of the evolutional behavior, which is characterized by a solid-like behavior at rest and a liquid flow during shearing. The microstructure evolution of ZL101 alloy at different temperatures from 540 to 580 ?C has been studied. Results show that the eutectic temperature can affect the transformation speed of semi-solid structure. Semi-solid microstructures with high solid fraction can be obtained by controlling the reheating time in less than 20min, while at the temperature lower than the eutectic temperature it needs more than one hour. Another character of semi-solid ZL101 alloy is the segregation of microstructures in semi-solid state, in which the liquid phase between the solid phases can flow freely and lead to the shrinkage of the sample during the heating process. As the holding time goes on, more shrinkage holes appear and change the surface of the specimen. These shrinkage holes are replenished by the liquid phase during compression deformation, resulting in the segregation of the components. Reference | Related Articles | Metrics | Comments（0）

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Analyzing Behavior Differences of Occupied and Non-Occupied Taxi Drivers Using Floating Car Data NIAN Guangyue1,2 (年光跃), LI Zhe2,3 (李喆), ZHU Weiquan4 (朱伟权), SUN Jian1,2* (孙健) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 682-687.   DOI: 10.1007/s12204-017-1890-9 Abstract （778）            Knowledge map    Save As the travel purpose of non-occupied taxies is to find new passengers rather than to arrive at the destination, large differences exist in the route choice behavior between the occupied and non-occupied taxies. With the assistance of geographic information system (GIS) and taxi-based floating car data (FCD), this paper investigates the behavior differences between occupied and non-occupied taxi drivers with the same origin and destination. Descriptive statistical indexes from the FCD in Shenzhen, China are explored to identify the route choice characteristics of occupied and non-occupied taxies. Then, a conditional logit model is proposed to model the quantitative relationship between drivers’ route choice and the related significant variables. Attributes of the variables related to non-occupied taxies’ observed routes are compared with the case of occupied ones. The results indicate that, compared with their counterparts, non-occupied taxi drivers generally pay more attention to choosing arterial roads and avoiding congested segments. Additionally, they are also found less sensitive to fewer traffic lights and shorter travel time. Findings from this research can assist to improve urban road network planning and traffic management. Reference | Related Articles | Metrics | Comments（0）

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An Improved General Bidirectional Progression Model for Arterial GUO Yajuan1,2 (郭亚娟), YANG Licai1* (杨立才), HAO Shenxue1 (郝慎学), GAO Jun3 (郜军) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 697-704.   DOI: 10.1007/s12204-017-1892-7 Abstract （613）            Knowledge map    Save Optimal control of arterial signals is critical for the effective operation of urban road network. With the goal of providing reasonable allocation of bidirectional green time while maximizing general bidirectional traffic progression along the arterial, this paper develops an improved general bidirectional coordinated progression model for arterial based on Maxband model. In the model, a proportional coefficient of bidirectional bandwidth demands is introduced and calibrated by adopting average link queue occupancy. The calibration method takes full account of actual traffic volume and capacity of each link, which helps to provide optimal control performance. Additionally, new constraints are added into the model and enable the model with two features: it can automatically select two-way or one-way progression, and the involved intersection unit can be either one-phase-one-approach or bidirectional symmetric release mode. The results of extensive simulation studies indicate that the improved model outperforms existing methods, markedly increasing the utilization of available bidirectional green time. Reference | Related Articles | Metrics | Comments（0）

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Prediction of COVID-19 Outbreak in China and Optimal Return Date for University Students Based on Propagation Dynamics HUANG Ganyu (黄甘雨), PAN Qiaoyi (潘荍仪), ZHAO Shuangying (赵双楹), GAO Yucen (高宇岑), GAO Xiaofeng (高晓沨) J Shanghai Jiaotong Univ Sci    2020, 25 (2): 140-146.   DOI: 10.1007/s12204-020-2167-2 Abstract （629）      PDF（pc） （550KB）（655）       Knowledge map    Save On 12 December 2019, a novel coronavirus disease, named COVID-19, began to spread around the world from Wuhan, China. It is useful and urgent to consider the future trend of this outbreak. We establish the 4+1 penta-group model to predict the development of the COVID-19 outbreak. In this model, we use the collected data to calibrate the parameters, and let the recovery rate and mortality change according to the actual situation. Furthermore, we propose the BAT model, which is composed of three parts: simulation of the return rush (Back), analytic hierarchy process (AHP) method, and technique for order preference by similarity to an ideal solution (TOPSIS) method, to figure out the best return date for university students. We also discuss the impacts of some factors that may occur in the future, such as secondary infection, emergence of effective drugs, and population flow from Korea to China. Reference | Related Articles | Metrics | Comments（0）

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Responses of the Strata and Supporting System to Dewatering in Deep Excavations XIAO Xiao (肖潇), ZHANG Yangqing (张扬清), LI Mingguang* (李明广), WANG Jianhua (王建华) Journal of Shanghai Jiao Tong University (Science)    2017, 22 (6): 705-711.   DOI: 10.1007/s12204-017-1884-7 Abstract （640）            Knowledge map    Save In order to prevent the inrushing caused by deep excavations, dewatering measure has to be adopted to decrease the confined water level. In this study, the responses of the strata and supporting system to dewatering in deep excavations are investigated through numerical simulations and case studies. Coupled fluid-mechanical analyses are performed by the use of the numerical software, FLAC3D. The responses of the ground settlement, base heave and interior columns to the excavation and dewatering are analyzed. Numerical results indicate that the dewatering measure can effectively reduce the uplift of the subsurface soil in the excavation, and decrease the vertical displacement of the supporting system. In addition, field data of two case histories show the similar responses and confirm the validation of the numerical results. Based on the analyses, dewatering in the confined aquifer is recommended as a construction method for controlling the vertical displacement of the strata and supporting system in deep excavations. Reference | Related Articles | Metrics | Comments（0）

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Preliminary Assessment of the COVID-19 Outbreak Using 3-Staged Model e-ISHR LI Sijia (李斯佳), SONG Kun (宋琨), YANG Boran (杨博然), GAO Yucen (高宇岑), GAO Xiaofeng (高晓沨) J Shanghai Jiaotong Univ Sci    2020, 25 (2): 157-164.   DOI: 10.1007/s12204-020-2169-0 Abstract （497）      PDF（pc） （472KB）（640）       Knowledge map    Save The outbreak of coronavirus disease 2019 (COVID-19) in Wuhan has aroused widespread concern and attention from all over the world. Many articles have predicted the development of the epidemic. Most of them only use very basic SEIR model without considering the real situation. In this paper, we build a model called e-ISHR model based on SEIR model. Then we add hospital system and time delay system into the original model to simulate the spread of COVID-19 better. Besides, in order to take the government’s control and people’s awareness into consideration, we change our e-ISHR model into a 3-staged model which effectively shows the impact of these factors on the spread of the disease. By using this e-ISHR model, we fit and predict the number of confirmed cases in Wuhan and China except Hubei. We also change some of parameters in our model. The results indicate the importance of isolation and increasing the number of beds in hospital. Reference | Related Articles | Metrics | Comments（0）

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Numerical Study on Flow Structure of a Shallow Laminar Round Jet CHEN Ke* (陈科), ZHAO Kai (赵恺), YOU Yunxiang (尤云祥) Journal of shanghai Jiaotong University (Science)    2017, 22 (3): 257-264.   DOI: 10.1007/s12204-017-1830-8 Abstract （889）            Knowledge map    Save The evolution mechanism and characteristics of the submerged laminar round jet in a viscous homogenous shallow water layer are investigated through computational modeling. The laminar mode is used to solve the Navier-Stokes equations. In order to visualize the formation and evolution of the flow pattern, the volume of fluid (VOF) method is adopted to simulate the free surface of the water layer below the air and to trace the jet fluid. The results show that the jet forms a class of quasi-two-dimensional (Q2D) vortex structures in the ambient fluid with unequal influence from the bottom wall and free surface. The time dependence of three parameters, defined for the flow pattern as jet length, spiral radius and pattern length, is investigated quantitatively in their non-dimensional forms. Three different Reynolds numbers and two injection durations are further considered to discuss their influence on the flow pattern. Reference | Related Articles | Metrics | Comments（0）

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Separation Method of Bi-directional Reflected Waves and Oblique Incident Regular Waves LI Jun1* (李 俊), CHEN Gang1,2 (陈 刚), YANG Jian-min1 (杨建民), PENG Tao1 (彭 涛) Journal of shanghai Jiaotong University (Science)    2013, 18 (6): 641-645.   DOI: 10.1007/s12204-013-1444-8 Abstract （792）            Knowledge map    Save Wave reflection is one of the key problems affecting wave simulation quality in ocean engineering basin. The deep ocean engineering basin is equipped with two-sided segmented wavemakers and two wave absorbing beaches, which are located opposite to wave generators to reduce wave reflection effects. When an oblique longcrested wave is made by two-sided segmented wavemakers in a wave basin, two bi-directional reflected waves with the same azimuth but opposite propagation directions are generated. According to this feature, based on the two-point approach developed by Goda, a method to separate an incident regular wave from two bi-directional reflected waves using three wave gauges is proposed. The validity of this method is proved by numerical composite waves. The results indicate that the method can separate incident wave from reflected waves effectively. The method can be used to determine the reflection coefficient and verify the capacity of wave absorbing beaches in deep ocean engineering basin. Reference | Related Articles | Metrics | Comments（0）

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Comments on Enhanced Yoking Proof Protocols for Radio Frequency Identification Tags and Tag Groups CHIEN Hung-yu (简宏宇), YEH Ming-kuei (叶明贵), WU Tzong-chen (吴宗成), LEE Chin-i (李静怡) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 604-609.   DOI: 10.1007/s12204-011-1196-2 Abstract （1945）            Knowledge map    Save Abstract:  A radio frequency identification (RFID) yoking proof scheme can generate proofs of simultaneous presence of two tags in the range of a specified reader so that an off-line verifier can verify the proofs later. This proof has found several interesting applications. However, many existing RFID yoking schemes are vulnerable to replay attacks. To overcome the weaknesses, Cho et al. proposed a new RFID yoking proof protocol and a new grouping protocol. Unfortunately, Cho et al.'s schemes are still vulnerable to replay attacks. In this paper, in addition to demonstrating weaknesses, we further discuss the rationale behind these weaknesses to provide a guide line for designing secure RFID yoking schemes. Based on the guide line, we propose a new RFID yoking scheme and a new RFID grouping scheme. Performance evaluation shows that our scheme outperforms its counterparts. Reference | Related Articles | Metrics | Comments（0）

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Looper-Tension  H∞ Control for Hot Strip Finishing Mills WANG Jing-cheng (王景成), ZHONG Zhao-zhun (仲兆准) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 519-523.   DOI: 10.1007/s12204-011-1188-2 Abstract （2557）            Knowledge map    Save Abstract:  The development of an innovative H∞ controller for looper and tension control in hot strip finishing mills is traced based on approximately linearized model. This solution has been considered thanks to its well-known robustness and simplicity characteristics concerning disturbances' attenuation. The controller is designed based on an optimal problem with linear matrix inequality (LMI) constraints, and the problem is solved by the mincx function of Matlab LMI Toolbox. Simulation results show the effectiveness of the proposed controller compared with conventional ones. Reference | Related Articles | Metrics | Comments（0）

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Bit Stream Oriented Enumeration Tree Pruning Algorithm QIU Wei-dong (邱卫东), JIN Ling (金 凌), YANG Xiao-niu (杨小牛), YANG Hong-wa (杨红娃) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 567-570.   DOI: 10.1007/s12204-011-1190-8 Abstract （1559）            Knowledge map    Save Abstract:  Packet analysis is very important in our digital life. But what protocol analyzers can do is limited because they can only process data in determined format. This paper puts forward a solution to decode raw data in an unknown format. It is certain that data can be cut into packets because there are usually characteristic bit sequences in packet headers. The key to solve the problem is how to find out those characteristic sequences. We present an efficient way of bit sequence enumeration. Both Aho-Corasick (AC) algorithm and data mining method are used to reduce the cost of the process. Reference | Related Articles | Metrics | Comments（0）

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The Underground Sewer Drainage Design Analysis of Highway Subgrade Under Evaporation LIU Jie* (刘 杰), YAO Hai-lin (姚海林), LU Zheng (卢 正), YOU Hui-jie (游慧杰), DUAN Jian-xin (段建新) Journal of shanghai Jiaotong University (Science)    2013, 18 (3): 289-292.   DOI: 10.1007/s12204-013-1396-z Abstract （796）            Knowledge map    Save According to the water balance principle, the expression of the phreatic table is established by considering evaporation and considering evaporation & drainage respectively. The law of phreatic table variation under the combined effects of considering evaporation & drainage is obtained. Based on Newton-Raphson iterative method, calculation and analysis programs are done to solve the first order implicit differential equation of the sewer drainage calculation considering phreatic evaporation. The calculation results show: after considering phreatic evaporation, in the need of reducing the same height of phreatic, the sewer spacing is appropriately larger than the case which didn’t consider the affection of phreatic evaporation; the phreatic drop speed in both effects of evaporation and drainage is faster than the case of just considering the drainage effect. Phreatic evaporation has a great influence to the subgrade sewer distance, phreatic evaporation needs to be considered in the subgrade drainage design. Reference | Related Articles | Metrics | Comments（0）

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Lift Distribution Based Design of Two-Dimensional Sections RAO Zhiqiang (饶志强), YANG Chenjun* (杨晨俊) Journal of shanghai Jiaotong University (Science)    2017, 22 (3): 265-273.   DOI: 10.1007/s12204-017-1831-7 Abstract （805）            Knowledge map    Save A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The effect of fluid viscosity on total lift is taken into account by coupling Reynolds-averaged Navier-Stokes (RANS) simulation with the potential-flow based design procedure. The present method avoids the difficulty of assigning velocity or pressure distributions on section surfaces. As the loading and thickness distributions are expressed in parametric forms, it is easy to ensure that the designed geometry is continuous and smooth. The effects of lift and thickness distributions on cavitation bucket are numerically investigated. A shift of lift loading towards the aft part of section tends to decrease the margin of back cavitation, while the width of cavitation bucket can be kept almost unchanged. To have a wider cavitation bucket, one can increase the leading edge radius, move properly the location of maximum thickness towards the leading edge, or decrease the curvature at the location of maximum thickness. Reference | Related Articles | Metrics | Comments（0）

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Reputation-Based Collaborative Spectrum Sensing Scheme in Cognitive Radio Networks ZHAO Shi-kang (赵士康), HE Di (何 迪), LI Wen-hua (李文化), ZHU Fu-sheng (朱伏生) Journal of shanghai Jiaotong University (Science)    2011, 16 (6): 641-647.   DOI: 10.1007/s12204-011-1204-6 Abstract （2480）            Knowledge map    Save  Collaborative spectrum sensing is proposed to improve the detection performance in cognitive radio (CR) networks. However, most of the current collaborative sensing schemes are vulnerable to the interference of the malicious secondary users (SUs). In this paper we propose a reputation-based collaborative spectrum sensing scheme to improve the security of cooperative sensing by mitigating the impacts of misbehaviors. The fusion center calculates the reputation rating of each SU according to their history reports to weight their sensing results in the proposed scheme. We analyze and evaluate the performance of the proposed scheme and its advantages over previous schemes in expansibility and integrity. Simulation results show that the proposed scheme can minimize the harmful influence from malicious SUs. Reference | Related Articles | Metrics | Comments（0）

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Genetic Programming Using Dynamic Population Variation for Computational Efforts Reduction in System Modeling TAO Yan-yun1 (陶砚蕴), CAO Jian 1,2 (曹健), LI Ming-lu 1,2 (李明禄) Journal of shanghai Jiaotong University (Science)    2012, 17 (2): 190-196.   DOI: 10.1007/s12204-012-1251-7 Abstract （1506）            Knowledge map    Save In this paper, we propose genetic programming (GP) using dynamic population variation (DPV) with four innovations for reducing computational efforts. A new stagnation phase definition and characteristic measure are defined for our DPV. The exponential pivot function is proposed to our DPV method in conjunction with the new stagnation phase definition. An appropriate population variation formula is suggested to accelerate convergence. The efficacy of these innovations in our DPV is examined using six benchmark problems. Comparison among the different characteristic measures has been conducted for regression problems and the new proposed measure outperformed other measures. It is proved that our DPV has the capacity to provide solutions at a lower computational effort compared with previously proposed DPV methods and standard genetic programming in most cases. Meanwhile, our DPV approach introduced in GP could also rapidly find an excellent solution as well as standard GP in system modeling problems. Reference | Related Articles | Metrics | Comments（0）

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Investigation of Improved Approaches to Bayes Risk Decoding XU Hai-hua (徐海华), ZHU Jie (朱 杰) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 524-529.   DOI: 10.1007/s12204-011-1189-1 Abstract （1856）            Knowledge map    Save Abstract:  Bayes risk (BR) decoding methods have been widely investigated in the speech recognition area due to its flexibility and complexity compared with the maximum a posteriori (MAP) method regarding to minimum word error (MWE) optimization. This paper investigates two improved approaches to the BR decoding, aiming at minimizing word error. The novelty of the proposed methods is shown in the explicit optimization of the objective function, the value of which is calculated by an improved forward algorithm on the lattice. However, the result of the first method is obtained by an expectation maximization (EM) like iteration, while the result of the second one is achieved by traversing the confusion network (CN), both of which lead to an optimized objective function value with distinct approaches. Experimental results indicate that the proposed methods result in an error reduction for lattice rescoring, compared with the traditional CN method for lattice rescoring. Reference | Related Articles | Metrics | Comments（0）

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External Equality and Absolute Equality Coincide in Finite CCS and π Calculus Without Summation JIN Yun (金 云) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 533-537.   DOI: 10.1007/s12204-011-1183-7 Abstract （1694）            Knowledge map    Save Abstract:  External equality and absolute equality are defined model independently by Fu. It is interesting and important to know whether these two equalities coincide or not. There are some results in Fu's paper for this issue. It is relatively easy to prove the coincidence if the summation operator is in the language, otherwise it is harder. In fact Fu proposed it as an open problem whether the two equalities coincide in some languages without summation. In this paper, the proofs of the coincidence in finite CCS and π calculus without summation are given. Reference | Related Articles | Metrics | Comments（0）

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In-Vitro and In-Vivo Electrical Characteristics of a Penetrating Microelectrode Array for Optic Nerve Electrical Stimulation SUI Xiao-hong (隋晓红), Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 614-619.   DOI: 10.1007/s12204-011-1198-0 Abstract （1505）            Knowledge map    Save Abstract:  The Chinese C-Sight team aims to restore vision to blind patients by means of stimulating the optic nerve with a penetrating microelectrode array. A biocompatible, implantable microwire array was developed having four platinum-iridium shafts, each 100 µm in diameter. This penetrating microwire array is described in this paper, including its fabrication techniques and its in-vitro electrical characteristics. Every set of four shafts was spaced 0.4 mm from center to center, comprising two short shafts that were 0.3 mm long and two that were 0.9 mm long. This design was intended to stimulate ganglion cell axons at different depths within the optic nerve. In-vitro electrochemical impedance testing results showed that the impedance at 1 kHz ranged from 8 to 10 kΩ at room temperature. The voltage responses of the arrays to current pulse stimulation indicated a charge-injection capacity of 210 µC/cm2. Finally, in-vivo acute animal experiments showed that the amplitude of the electrically evoked potentials (EEPs) measured in primary visual cortex could be as large as 100 μV upon direct stimulation of the optic nerve. Reference | Related Articles | Metrics | Comments（0）

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Threshold Signature Scheme with Threshold Verification Based on Multivariate Linear Polynomial SHEN Zhong-hua (沈忠华), YU Xiu-yuan (于秀源) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 551-556.   DOI: 10.1007/s12204-011-1186-4 Abstract （1475）            Knowledge map    Save Abstract:  Secret sharing schemes are multi-party protocols related to key establishment. They also facilitate distributed trust or shared control for critical activities (e.g., signing corporate cheques and opening bank vaults), by gating the critical action on cooperation from t(t∈  Z+) of n(n∈  Z+) users. A (t, n) threshold scheme (t<n) is a method by which a trusted party computes secret shares γi (1≤i≤ n) from an initial secret γ0 and securely distributes γi to user. Any t or more users who pool their shares may easily recover γ0, but any group knowing only t-1 or fewer shares may not. By the ElGamal public key cryptophytes and the Schnorr's signature scheme, this paper proposes a new (t,n) threshold signature scheme with (k,m) (k,m∈Z+) threshold verification based on the multivariate linear polynomial. Reference | Related Articles | Metrics | Comments（0）

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Optimization Design and Experiment of the Radio Frequency Transmission Utilized in Video Capsule Endoscope LIU Gang* (刘刚), YAN Guozheng (颜国正), ZHU Bingquan (朱柄全), XU Wenming (徐文铭) Journal of shanghai Jiaotong University (Science)    2016, 21 (1): 1-6.   DOI: 10.1007/s12204-016-1692-5 Abstract （573）            Knowledge map    Save In view of fuzzy and unstable images received in video capsule endoscopy, and the poor communication effect, an improved radio frequency (RF) transmission circuit module with low power consumption and helix antenna is designed to improve the performance of video transmission and to extend the working time of the capsule. Simulation and analysis of the circuits and antenna with HFSS12 and ADS2011 software are highlighted. Video capsule endoscope prototypes are made and evaluated to verify the feasibility of the proposed design. In vitro tests and animal experiments show that the results of the antenna tests basically meet the simulation, and the power consumption of RF circuit is 15.9mV. The video capsule endoscope works well with the receiver with multiple receiving antennas, and the working time is more than 9 h. It can realize the wireless transmission of the video data, and images received are clear and stable in comparison with the previous designs. Reference | Related Articles | Metrics | Comments（0）

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Certificateless Message Recovery Signatures Providing Girault's Level-3 Security TSO Ray-lin (左瑞麟), KIM Cheonshik, YI Xun (易 训) Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 577-585.   DOI: 10.1007/s12204-011-1192-6 Abstract （1580）            Knowledge map    Save Abstract:  A digital signature with message recovery is a signature that the message itself (or partial of the message) is not required to be transmitted together with the signature. It has the advantage of small data size of communication comparing with the traditional digital signatures. In this paper, combining both advantages of the message recovery signatures and the certificateless cryptography, we propose the first certificatelss signature scheme with message recovery. The remarkable feature of our scheme is that it can achieve Girault's Level-3 security while the conventional certificateless signature scheme only achieves Level-2 security. The security of the scheme is rigorously proved in the random oracle model based on the hardness of the k bilinear Diffie-Hellman inverse (k-BDHI) problem. Reference | Related Articles | Metrics | Comments（0）

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Accurate 3D Reconstruction of Subject-Specific Knee Finite Element Model to Simulate the Articular Cartilage Defects DONG Yue-fu (董跃福), HU Guang-hong (胡广洪), ZHANG Luo-lian (张罗莲), HU Yang (胡 杨) DONG Ying-hai (董英海), XU Qing-rong Journal of shanghai Jiaotong University (Science)    2011, 16 (5): 620-627.   DOI: 10.1007/s12204-011-1199-z Abstract （2277）            Knowledge map    Save Abstract:  The biomechanical relationship between the articular cartilage defect and knee osteoarthritis (OA) has not been clearly defined. This study presents a 3D knee finite element model (FEM) to determine the effect of cartilage defects on the stress distribution around the defect rim. The complete knee FEM, which includes bones, articular cartilages, menisci and ligaments, is developed from computed tomography and magnetic resonance images. This FEM then is validated and used to simulate femoral cartilage defects. Based on the obtained results, it is confirmed that the 3D knee FEM is reconstructed with high-fidelity level and can faithfully predict the knee contact behavior. Cartilage defects drastically affect the stress distribution on articular cartilages. When the defect size was smaller than 1.00 cm2, the stress elevation and redistribution were found undistinguishable. However, significant stress elevation and redistribution were detected due to the large defect sizes (≥1.00 cm2. This alteration of stress distribution has important implications relating to the progression of cartilage defect to OA in the human knee joint. Reference | Related Articles | Metrics | Comments（0）