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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
    Abstract239)      PDF (1891KB)(418)      
    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. 
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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
    Abstract467)      PDF (748KB)(730)      
    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.
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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
    Abstract192)      PDF (1518KB)(172)      
    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.
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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
    Abstract452)      PDF (472KB)(521)      
    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.
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    Calibration Technology of Optical Fiber Strain Sensor
    CHEN Gang(陈刚), LIU Hongyue(刘宏月), GAO Ruiriang(高瑞翔)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 551-559.   DOI: 10.1007/s12204-022-2406-9
    Abstract86)      PDF (1122KB)(62)      
    As one of the hotspots of sensing technology at present, optical fiber sensor has the characteristics of small size, anti-electromagnetic interference, and easy networking, which plays an irreplaceable role in multiphysics parameter monitoring of complex electromagnetic environments. The precise calibration of the optical fiber strain sensor has great practical value in prolonging the survival rate of the sensor, improving the measurement accuracy, and meeting the needs of long-term monitoring. By reviewing the research status of strain sensor calibration method and fiber optic strain sensor calibration method, the advantages and disadvantages of the main methods are analyzed separately from the static and dynamic perspectives, and the development prospect of the calibration technology of optic fiber strain sensor is summarized.
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    Using a Patient-Specific 3D-Printed Surgical Guide for High Tibial Osteotomy: A Technical Note
    JIANG Xu, (江旭), XIE Kai (谢凯), LI Bo (李波), HU Xumin (胡旭民), WU Haishan (吴海山), GAO Liangbin (高梁斌), WANG Liao (王燎), YAN Mengning (严孟宁)
    J Shanghai Jiaotong Univ Sci    2021, 26 (3): 339-345.   DOI: 10.1007/s12204-021-2302-8
    Abstract281)      PDF (1004KB)(190)      
    Patient-specific instrumentation (PSI) enables a more accurate alignment of the lower limbs in a high  tibial osteotomy (HTO) than in traditional surgery; however, the current design of commercial PSIs is not perfect.  Therefore, we designed a new patient-specific surgical guide to improve the accuracy of the osteotomy and verified  its reliability through a clinical operation. Here, we describe a patient with isolated medial-compartment bilateral  knee osteoarthritis, accompanied by a varus deformity of the proximal tibia. The patient was treated with HTO  using a patient-specific 3D-printed surgical guide. We concluded that the patient-specific 3D-printed surgical  guide improved the accuracy of the osteotomy and the alignment of the lower limb. 
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    Intelligent-Assist Algorithm for Remote Shared-Control Driving Based on Game Theory
    QIAO Bangjun∗ (乔邦峻), LI Huanghe (李黄河), WU Xiaodong (吴晓东)
    J Shanghai Jiaotong Univ Sci    2021, 26 (5): 615-625.   DOI: 10.1007/s12204-021-2351-z
    Abstract154)      PDF (759KB)(299)      
    Contemporary autonomous-driving technology relies on good environmental-perception systems and high-precision maps. For unknown environments or scenarios where perception fails, a human-in-the-loop remote-driving system can effectively complement common solutions, although safety remains an issue for its application. A haptic shared-control algorithm based on non-cooperative game theory is presented in this paper. The algorithm generates collision-free reference paths with model predictive control and predicts the driver’s path using a two-point preview model. Man-machine torque interaction is modeled as a Nash game, and the assist system’s degree of intervention is regulated in real time, according to assessments of collision risk and the driver’s concentration. Simulations of several representative scenarios demonstrate how the proposed method improves driving safety, while respecting driver decisions.
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    Simulation of Bimodal Fiber Distribution Effect on Transient Accumulation of Particles During Filtration
    AKAMPUMUZA Obed, WU Jiajun (吴佳骏), QUAN Zhenzhen (权震震), QIN Xiaohong (覃小红)
    J Shanghai Jiaotong Univ Sci    2021, 26 (2): 176-185.   DOI: 10.1007/s12204-020-2251-7
    Abstract273)      PDF (1849KB)(156)      
    Modeling has become phenomenal in developing new products. In the case of filters, one of the most applied procedures is via the construction of idealized physical computational models bearing close semblance to real filter media. It is upon these that multi-physics tools were applied to analyze the flow of fluid and the resulting typical performance parameters. In this work, two 3D filter membranes were constructed with MATLAB; one had a random distribution of unimodal nanofibers, and the other, a novel modification, formed a bimodal distribution; both of them had similar dimensions and solid volume fractions. A comparison of their performance in a dust-loading environment was made by using computational fluid dynamic-discrete element method (CFD-DEM) coupling technique in STAR-CCM+. It was found that the bimodal nanofiber membrane greatly improved the particle capture efficiency. Whereas this increased the pressure drop, the gain was not too significant. Thus, overall, the results of the figure of merit proved that adopting a bimodal formation improved the filter's quality.
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    Accuracy Assessment of a Novel Radiographic Method to Evaluate Guided Bone Regeneration Outcomes Using a 3D-Printed Model
    SHI Junyu (史俊宇), LI Yuan (李元), ZHANG Xiao (张枭), ZHANG Xiaomeng (张晓梦), LAI Hongchang (赖红昌)
    J Shanghai Jiaotong Univ Sci    2021, 26 (3): 284-289.   DOI: 10.1007/s12204-021-2294-4
    Abstract336)      PDF (966KB)(89)      
    The aim of this study was to evaluate the accuracy and reproducibility of a morphological contour  interpolation (MCI) based segmentation method for the volumetric measurement of bone grafts around implants.  Three 3D-printed models (one with a cylinder and two with a geometrically-complex form) were fabricated to  simulate implant placement with a simultaneous guided bone regeneration (GBR) procedure. All models were  scanned using a cone beam computed tomography (CBCT) instrument with the same parameters. The true  volumes of the bone grafts in the models were assessed using computer-aided calculation (controls). For the test  measurements, both manual and MCI-based methods were used. A comparison between the measured and true  volumes was performed to evaluate the accuracy. The coefficients of variation of repeated measurements were  calculated to evaluate the reproducibility. In addition, the execution time was recorded and a comparison between  the two methods was performed. The high accuracy of the MCI-based method was found with differences between  the measured value and actual volume, which never exceeded 7.3%. Excellent reproducibility was shown, with  coefficients of variation never exceeding 1.1%. A shorter execution time was observed for the MCI-based method  than for the manual method. Within the confines of this study, the MCI-based method may be suitable for  volumetric measurements of grafted bone around implants.
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    Design and Application of 3D Printing Based Personalised Pelvic Prostheses
    WU Junxiang (吴钧翔), LUO Dinghao(罗丁豪), XIE Kai (谢凯), WANG Lei (王磊), HAO Yongqiang (郝永强)
    J Shanghai Jiaotong Univ Sci    2021, 26 (3): 361-367.   DOI: 10.1007/s12204-021-2305-5
    Abstract218)      PDF (930KB)(86)      
    In this paper, we describe the design and surgical process of personalised pelvic prostheses fixation  through 3D printing according to different Enneking pelvic tumour zones: the ilium (Zone I), acetabulum (Zone  II), and pubis and ischium (Zone III). A 3D model of the pelvis was reconstructed using imaging data, and the  parameters on the planes of the acetabulum and pelvic incisal margin were measured. The main body of the pelvic  prosthesis was constructed, a porous structure was designed on the bone-prosthesis interface, and the movement  paths, lengths, and diameters of screws were planned. By combining the pathological model and osteotomy guide,  limb salvage reconstruction was performed in patients with pelvic tumours. Preoperative and postoperative data  were compared to verify the prosthesis stability. Our investigation revealed that the long-term survival of pelvic  reconstruction prostheses depends on accurate matching with the bone defect area, good initial stability, and a  porous structure to allow bone ingrowth. 
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    Biomechanical Analysis of Personalised 3D-Printed Clavicle Plates of Different Materials to Treat Midshaft Clavicle Fractures
    CHENG Rongshan, (程荣山), JIANG Ziang, (蒋子昂), DIMITRIOU Dimitris, GONG Weihua, (龚伟华), TSAI Tsung-Yuan, (蔡宗远)
    J Shanghai Jiaotong Univ Sci    2021, 26 (3): 259-266.   DOI: 10.1007/s12204-021-2291-7
    Abstract323)      PDF (1656KB)(280)      
    This study was aimed at comparing the biomechanical performance of personalised 3D-printed clavicle  plates of different materials to treat midshaft clavicle fractures with the finite element (FE) method. The FE  model of a fractured clavicle with a personalised 3D-printed clavicle plate and screws was constructed. Three  types of materials were simulated, including stainless steel, titanium alloy, and magnesium alloy. Two loading  conditions (axial compression and inferior bending) were applied at the distal end of the clavicle to simulate arm  abduction. Plate stiffness, peak stress, and bone strain at the clavicle fracture site were measured and compared.  The stiffness of the stainless steel clavicle plate was significantly greater than that of the titanium alloy clavicle  plate. The stiffness of the magnesium alloy clavicle plate was similar to that of the intact clavicle; peak stress  of the magnesium alloy clavicle plate was the lowest; thus, it had less stress-shielding effects on bone formation.  The magnesium alloy clavicle plate was more likely to form bone by distributing proper strain at the clavicle  fracture site. According to the influence of different materials on the tensile strength, magnesium alloy clavicle  plates might be preferred owing to their bionic stiffness in the treatment of patients with a low risk of falling. For  patients who engage in contact sports, a titanium alloy clavicle plate might be more suitable.
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    High-Speed Fault-Tolerant Finite Impulse Response Digital Filter on Field Programmable Gate Array
    WU Tao (吴焘)
    J Shanghai Jiaotong Univ Sci    2021, 26 (4): 554-558.   DOI: 10.1007/s12204-020-2214-z
    Abstract301)      PDF (720KB)(112)      
    Some fast finite impulse response (FIR) filters use a large number of look-up tables (LUTs) to configure distributed random-access memories (RAMs) and save registers. The distributed RAMs store 2M precomputed sums of M permuted operands in order to simplify the accumulation, which lays similarity to the solution of Boolean satisfiability (SAT) problem. In this work, a high-speed fault-tolerant FIR digital filter on field programmable gate array (FPGA) is proposed for hardware implementation. A shift register and an RAM are used to arrange the data flow. Generally, an N-tap digital filter only requires N embedded multipliers on FPGA. The better performance is due to high-radix words and low-latency operations. A 32-tap 8-bit FIR digital filter enjoys a throughput of 9.17MB/s, taking 109 ns to calculate one convolution. In addition, a fault-tolerant scheme by majority logic is used to correct real-time errors within digital filters.

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    High Curvature Stripe Profile Extraction Algorithm of Line Structured Light Measuring System
    SUN Hao (孙昊), DU Xuan (杜宣), LÜ Na(吕娜), CUI Bin(崔斌), ZHA Hui(赵辉)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 560-568.   DOI: 10.1007/s12204-022-2476-8
    Abstract63)      PDF (1375KB)(40)      
    In the line structured light measuring system, the accuracy of the process of laser stripe directly affects the measurement results. Therefore, the extraction algorithm for the laser stripe, especially the surface with high reflection and high curvature, is very important. The imaging principle of line structured light, the light intensity distribution law of laser stripe and the extraction algorithm have been studied, and a stripe profile extraction method based on real light intensity distribution has been proposed. In this algorithm, fast region of interest extraction, stripe width estimation, and adaptive filtering on the striped image are performed. Then the energy center of the stripe at the sub-pixel level is extracted. Finally, the low-quality center points are eliminated, and the context information is used to recover the missing central points. Simulated images generated based on the imaging principle of line structured light and real experimental images were used to evaluate the accuracy and repeatability of the proposed method. The results show that the method behaves excellently at the edges of high-curvature stripes; the maximum error is only 1.6 pixels, which is 1/10 of the classic Steger algorithm; the experiment repeatability is only 8.8 μm, which is 2.7 times that of the Steger method. Therefore, the proposed method improves the accuracy of object contour extraction, and it is especially suitable for contour detection of objects with high curvature.
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    Meso-Scale Tearing Mechanism Analysis of Flexible Fabric Composite for Stratospheric Airship via Experiment and Numerical Simulation
    CHEN Yonglin (陈永霖), YANG Weidong (杨伟东), XIE Weicheng (谢炜程), WANG Xiaoliang (王晓亮), FU Gongyi∗ (付功义)
    J Shanghai Jiaotong Univ Sci    2022, 27 (6): 873-884.   DOI: 10.1007/s12204-022-2431-8
    Abstract110)      PDF (4194KB)(68)      
    Stratospheric airships are controllable lighter-than-air aircraft and have great potential application in surveillance and communication. The envelopes, one of the main structures of a stratospheric airship, are generally made of flexible fabric composites to be lightweight, high strength, capable of containing lifting gas, and resistant to the harsh stratospheric environment. The composites, however, are prone to tearing. Hence, their tearing behavior has attracted great attention. This paper explores the meso-scale tearing mechanism of an envelope and the temperature influence on its tear strength via experiment and numerical simulation. Biaxial tear tests were conducted on cruciform specimens, which were contacted with liquids (cold alcohol or hot water) at different temperatures including -25, 20, 50, 80 °C. The specimens’ tear stresses were measured and the meso-scale tearing behavior was captured with a microscope. Besides, a novel finite element analysis model based on truss and spring elements was established to simulate the tearing behavior. It was found that the simulation result has a relative agreement with the tests. The simulation results show that the maximum tear stress of the envelope drops by 39.62% as the temperature rises from -60 °C to 80 °C and the tensile properties of yarns and matrix account for stress concentration around a crack tip. This work deeply reveals the meso-scale tearing mechanism of the envelope and provides a valuable reference for exploring tearing properties of flexible fabric composites.
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    Early Detection Methods of Deep Tissue Pressure Injuries: A Systematic Review
    JIA Jingyil (贾菁怡),LI Zhengyi1,2 (李正裔),PENG Linjing1 (彭琳晶),YAO Yifeil* (姚怡飞)
    J Shanghai Jiaotong Univ Sci    2023, 28 (4): 526-.   DOI: 10.1007/s12204-022-2518-2
    Abstract103)      PDF (551KB)(43)      
    Deep tissue pressure injuries (DTPIs) have witnessed a growing prevalence in hospitals and other health care units especially among individuals with pathological conditions that give rise to restricted mobility, impaired sensation, and reduced tissue tolerance. The etiology of DTPIs has been a subject of controversy, to which several explanatory models have been proposed, including direct mechanical insult, ischemia-reperfusion, lymphatic occlusion, and inflammatory cytokines. In line with these pathophysiological scenarios, ultrasound, subepidermal moisture detection, and biomarker technologies have been proposed as potential early detection methods of DTPIs. This paper provides a systematic review involving these three methods. The conclusion is that combining and implementing these methods at different time periods during DTPIs development and progression respectively is likely to be the most universal, effective and promising way for DTPIs diagnosis.
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    Two Generative Design Methods of Hospital Operating Department Layouts Based on Healthcare Systematic Layout Planning and Generative Adversarial Network
    ZHAO Chaowang (赵朝望), YANG Jian (杨健), XIONG Wuyue (熊吴越), LI Jiatong (李佳潼)
    J Shanghai Jiaotong Univ Sci    2021, 26 (1): 103-115.   DOI: 10.1007/s12204-021-2265-9
    Abstract455)      PDF (1551KB)(248)      
    With the increasing demands of health care, the design of hospital buildings has become increasingly demanding and complicated. However, the traditional layout design method for hospital is labor intensive, time consuming and prone to errors. With the development of artificial intelligence (AI), the intelligent design method has become possible and is considered to be suitable for the layout design of hospital buildings. Two intelligent design processes based on healthcare systematic layout planning (HSLP) and generative adversarial network (GAN) are proposed in this paper, which aim to solve the generation problem of the plane functional layout of the operating departments (ODs) of general hospitals. The first design method that is more like a mathematical model with traditional optimization algorithm concerns the following two steps: developing the HSLP model based on the conventional systematic layout planning (SLP) theory, identifying the relationship and flows amongst various departments/units, and arriving at the preliminary plane layout design; establishing mathematical model to optimize the building layout by using the genetic algorithm (GA) to obtain the optimized scheme. The specific process of the second intelligent design based on more than 100 sets of collected OD drawings includes: labelling the corresponding functional layouts of each OD plan; building image-to-image translation with conditional adversarial network (pix2pix) for training OD plane layouts, which is one of the most representative GAN models. Finally, the functions and features of the results generated by the two methods are analyzed and compared from an architectural and algorithmic perspective. Comparison of the two design methods shows that the HSLP and GAN models can autonomously generate new OD plane functional layouts. The HSLP layouts have clear functional area adjacencies and optimization goals, but the layouts are relatively rigid and not specific enough. The GAN outputs are the most innovative layouts with strong applicability, but the dataset has strict constraints. The goal of this paper is to help release the heavy load of architects in the early design stage and present the effectiveness of these intelligent design methods in the field of medical architecture.

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    Fault Diagnosis for Rolling Element Bearing in Dataset Bias Scenario
    HOU Liangsheng(侯良生),ZHANG Jundong*(张均东)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 638-651.   DOI: 10.1007/s12204-021-2320-6
    Abstract16)      PDF (1574KB)(18)      
    Recently, data-driven methods, especially deep learning, outperform other methods for rolling element bearing (REB) fault diagnosis. Nevertheless, most research work assumes that REB dataset is unbiased. In the real industry applications, the dataset bias exists with REB owing to varying REB working conditions and noise interference. Recently proposed adversarial discriminative domain adaptation (ADDA) is an increasingly popular incarnation to solve dataset bias problem. However, it mainly devotes to realizing domain alignments, and ignores class-level alignments; it can cause degradation of classification performance. In this study, we propose a new REB fault diagnosis model based on improved ADDA to address dataset bias. The proposed diagnosis model realizes domain- and class-level alignments in dataset bias scenario; it consists of two feature extractors, a domain discriminator, and two label classifiers. The feature extractors and domain discriminator are trained in an adversarial manner to minimize the domain difference in feature extractors. The domain discrepancy in label classifier is reduced by minimizing correlation alignment (CORAL) loss. We evaluate the proposed model on the Case Western Reserve University (CWRU) bearing dataset and Paderborn University bearing dataset. The proposed method yields better results than other methods and has good prospects for industrial applications.
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    High Curvature Stripe Profile Extraction Algorithm of Line Structured Light Measuring System
    CHEN Qiheng1(陈启恒),PENG Na2(彭娜),Lü Na1(吕娜),TAO Wei(陶卫),ZHAO Huil*(赵辉)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 577-586.   DOI: 10.1007/s12204-022-2414-9
    Abstract32)      PDF (1585KB)(18)      
    Non-uniformity of light sources is one of the inevitable error factors causing poor shape recovery accuracy of photometric stereo methods under close-range lighting with quasi point lights. Semi-calibrated photometric stereo methods are required to avoid repeated, tedious and impractical photometric calibration. In this paper, two simple, concise but effective mesh-based semi-calibrated photometric stereo methods are proposed. The proposed methods extend the traditional mesh-based photometric stereo methods and further allow joint and accurate estimation of normals and non-uniform light intensities by alternatively updating normals, depth maps and intensities. Extensive experiments are conducted to validate the effectiveness and robustness of the proposed algorithms. Even under extremely severe non-uniform lighting, the proposed methods can still suppress the error and improve the shape recovery accuracy by up to 65.6% in real-world experiments.
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    Parameter Optimization and Precision Enhancement of Dual-Coil Eddy Current Sensor
    ZHANG Zhenning1(张振宁),LIU Qiang2(刘强), Lü Chunfeng3(吕春峰),MAO Yimeil(毛义梅),TAo Weil(陶卫),ZHAO Huil*(赵辉)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 596-603.   DOI: 10.1007/s12204-022-2511-9
    Abstract31)      PDF (947KB)(18)      
    To enhance the measurement precision of eddy current sensor in particular environments such as extreme temperature changes and limited available space in aerospace, we optimized the structural parameters of the traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulation modeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. The simulation results are verified by setting up an experimental platform. For the extreme temperature environment, the displacement measurement error caused by the full range temperature variation of the dual-coil sensor under the optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified the thermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation, the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor. The method proposed in this paper can provide a design reference for the structural optimization of the axial dual-coil eddy current sensor probe.
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    Lightweight Method for Vehicle Re-identification Using Reranking Algorithm Based on Topology Information of Surveillance Network
    ZOU Yue (邹 悦), LI Lin (李 霖), YANG Xubo (杨旭波)
    J Shanghai Jiaotong Univ Sci    2021, 26 (5): 577-586.   DOI: 10.1007/s12204-021-2347-8
    Abstract247)      PDF (1353KB)(105)      
    As an emerging visual task, vehicle re-identification refers to the identification of the same vehicle across multiple cameras. Herein, we propose a novel vehicle re-identification method that uses an improved ResNet-50 architecture and utilizes the topology information of a surveillance network to rerank the final results. In the training stage, we apply several data augmentation approaches to expand our training data and increase their diversity in a cost-effective manner. We reform the original RestNet-50 architecture by adding non-local blocks to implement the attention mechanism and replacing part of the batch normalization operations with instance batch normalization. After obtaining preliminary results from the proposed model, we use the reranking algorithm, whose core function is to improve the similarity scores of all images on the most likely path that the vehicle tends to appear to optimize the final results. Compared with most existing state-of-the-art methods, our method is lighter, requires less data annotation, and offers competitive performance.
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    Novel Data Placement Algorithm for Distributed Storage System  Based on Fault-Tolerant Domain
    SHI Lianxing (石连星), WANG Zhiheng (王志恒), LI Xiaoyong (李小勇)
    J Shanghai Jiaotong Univ Sci    2021, 26 (4): 463-470.   DOI: 10.1007/s12204-020-2253-5
    Abstract253)      PDF (1240KB)(147)      
    The 3-replica redundancy strategy is widely used to solve the problem of data reliability in large-scale distributed storage systems. However, its storage capacity utilization is only 33%. In this paper, a data placement algorithm based on fault-tolerant domain (FTD) is proposed. Owing to the fine-grained design of the FTD, the data reliability of systems using two replicas is comparable to that of current mainstream systems using three replicas, and the capacity utilization is increased to 50%. Moreover, the proposed FTD provides a new concept for the design of distributed storage systems. Distributed storage systems can take FTDs as the units for data placement, data migration, data repair and so on. In addition, fault detection can be performed independently and concurrently within the FTDs.

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    Information Entropy of Angular Spectrum for Quantitatively Evaluating Eddy Current Distribution Varying in Time Domain
    CHEN Guolong*(陈国龙),WANG Kang(王﹐慷),CAO Zheng (曹﹐政),JIN Wuyin(靳伍银)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 587-595.   DOI: 10.1007/s12204-022-2475-9
    Abstract25)      PDF (1330KB)(17)      
    Eddy current (EC) distribution induced by EC sensors determines the interaction between the defect in the testing specimen and the EC, so quantitatively evaluating EC distribution is crucial to the design of EC sensors. In this study, two indices based on the information entropy are proposed to evaluate the EC energy allocated in different directions. The EC vectors induced by a rotational field EC sensor varying in the time domain are evaluated by the proposed methods. Then, the evaluating results are analyzed by the principle of EC testing. It can be concluded that the two indices can effectively quantitatively evaluate the EC distributions varying in the time domain and are used to optimize the parameters of the rotational EC sensors.
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    Numerical Study on Separation of Circulating Tumor Cell Using Dielectrophoresis in a Four-Electrode Microfluidic Device
    WANG Yukuna (王雨坤), DING Xiantingb (丁显廷), ZHANG Zhinana (张执南)
    J Shanghai Jiaotong Univ Sci    2023, 28 (4): 391-.   DOI: 10.1007/s12204-022-2459-9
    Abstract192)      PDF (1462KB)(176)      
    This numerical study proposes a cell sorting technique based on dielectrophoresis (DEP) in a microfluidic chip. Under the joint effect of DEP and fluid drag, white blood cells and circulating tumor cells are separated because of different dielectric properties. First, the mathematical models of device geometry, single cell, DEP force, electric field, and flow field are established to simulate the cell motion. Based on the simulation model, important boundary parameters are discussed to optimize the cell sorting ability of the device. A proper matching relationship between voltage and flow rate is then provided. The inlet and outlet conditions are also investigated to control the particle motion in the flow field. The significance of this study is to verify the cell separating ability of the microfluidic chip, and to provide a logistic design for the separation of rare diseased cells.
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    Clinical Observation of 3D Printing Technology in Insoles for Flexible Flatfoot Patients
    WANG Yitian (王一天), JIANG Wenbo (姜闻博), GAN Yaokai, (干耀恺), YU Yang (于洋), DAI Kerong, (戴尅戎)
    J Shanghai Jiaotong Univ Sci    2021, 26 (3): 398-403.   DOI: 10.1007/s12204-021-2311-7
    Abstract303)      PDF (567KB)(118)      
    Flatfoot is defined as the flattening of the medial arch of the foot, and it is classified into flexible  flatfoot and rigid flatfoot based on whether the flattening of the medial arch of the foot can be reset when  standing on toes. The insole is the most basic and common treatment, which is relatively cheaper and easier to  adopt. Three-dimensional (3D) printing, an emerging technology characterized by high machining accuracy and  use of various materials, can be utilised in personalised insoles, which have good application prospects. Further  research on the clinical effects of 3D-printed insoles is still needed. In this study, 64 cases of 3D-printed insoles  were clinically observed. The results showed that 3D-printed insoles had statistically positive effects in treating  flatfoot (P = 0.000 17), and with adjustment and adaptation, their comfort and clinical effect can be improved.  This study provides an empirical reference for further large-scale clinical control research. 
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    Dlung: Unsupervised Few-Shot Diffeomorphic Respiratory Motion Modeling
    CHEN Peizhi1,2* (陈培芝), GUO Yifan1 (郭逸凡),WANG Dahan1,2 (王大寒), CHEN Chinling1,3,4* (陈金铃)
    J Shanghai Jiaotong Univ Sci    2023, 28 (4): 536-.   DOI: 10.1007/s12204-022-2525-3
    Abstract80)      PDF (1719KB)(34)      
    Lung image registration plays an important role in lung analysis applications, such as respiratory motion modeling. Unsupervised learning-based image registration methods that can compute the deformation without the requirement of supervision attract much attention. However, it is noteworthy that they have two drawbacks: they do not handle the problem of limited data and do not guarantee diffeomorphic (topologypreserving) properties, especially when large deformation exists in lung scans. In this paper, we present an unsupervised few-shot learning-based diffeomorphic lung image registration, namely Dlung. We employ fine-tuning techniques to solve the problem of limited data and apply the scaling and squaring method to accomplish the diffeomorphic registration. Furthermore, atlas-based registration on spatio-temporal (4D) images is performed and thoroughly compared with baseline methods. Dlung achieves the highest accuracy with diffeomorphic properties. It constructs accurate and fast respiratory motion models with limited data. This research extends our knowledge of respiratory motion modeling.
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    CFD-Aided Investigation of Combined Flow Conditioners for Gas Ultrasonic Flow Meter
    YUAN Yaqi1(袁亚琦),LI Shiyangl*(李世阳),ZHENG Jia1(郑佳),LI Mingrui2(李明睿)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 611-620.   DOI: 10.1007/s12204-021-2378-1
    Abstract22)      PDF (3396KB)(14)      
    Stable and fully developed gas flow field is crucial for realizing accurate measurement of gas ultrasonic flow meter. To reduce the flow field distortion, a flow conditioner is usually used. However, the traditional monotype flow conditioner can only improve the flow field distribution partly. The measurement accuracy of the transit time ultrasonic flow meter is still affected because of its serious flow field distortion in the complex pipeline conditions. In this paper, to further improve the flow field distribution, a combined conditioner is investigated. The combined flow conditioner is composed of fan-shaped section, turbulent mixing cavity, and honeycomb-shaped section. The effects of fan blade angle and cavity length on the flow field of the DN50 flow meter are studied using computational fluid dynamics (CFD) simulation. Simulation results indicate that compared with the monotype conditioner, the combined conditioner has better performance on effectively reducing the swirl and turbulence and providing more stable and repetitive velocity profiles. Experiments also validate the effectiveness of the combined conditioner. The flow meter with the combined conditioner has better repeatability of less than 0.2%, which is better than those of the monotype conditioners under the same conditions. This work is very useful for accurate measurement of gas ultrasonic flow meter, especially for the complex pipeline conditions.
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    Measuring Transverse Relaxation Time of Xenon Atoms Based on Single Beam of Laser in Nuclear Magnetic Resonance Gyroscope
    ZHONG Guochen1(钟国宸),LIU Hual*(刘华), GUo Yang1(郭阳),LI Shaoliang2(李绍良),ZHAO Wanliang2(赵万良),CHENG Yuxiang2(成宇翔)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 569-576.   DOI: 10.1007/s12204-022-2436-3
    Abstract38)      PDF (1757KB)(16)      
    Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxation time (T2) of the xenon nuclear spin in the atomic cell of the NMRG directly affects the angular random walk of the gyro. Accurate and rapid measurement of T2 is conducive to further improvement of gyroscope. At present, for the measurement of T2, the schemes of two orthogonal lasers for pumping and detecting are usually used. By applying two fast-switching orthogonal static magnetic fields and a single beam of circularly polarized laser with corresponding wavelength to pump the atomic cell, the xenon nuclear macroscopic magnetic moment Larmor precession is generated. The cesium atoms parametric magnetometer in cell is formed to detect the free induction decay signal generated by nuclear spin precession of xenon atoms. The measurement of T2 by a single laser simplifies the measurement equipment compared with traditional method with two lasers. The experimental results show that the T2 of xenon atoms is more than 10 s, and the effects of temperature are studied, which lay the foundation for the subsequent improvement of gyro performance.
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    Developing High-Precision Maps for Automated Driving in China: Legal Obstacles and the Way to Overcome Them
    ZHANG Taolue∗ (张韬略), TU Huizhao (涂辉招), QIU Wei (邱 炜)
    J Shanghai Jiaotong Univ Sci    2021, 26 (5): 658-669.   DOI: 10.1007/s12204-021-2355-8
    Abstract230)      PDF (285KB)(106)      
    A high-precision map (HPM) is the key infrastructure to realizing the function of automated driving (AD) and ensuring its safety. However, the current laws and regulations on HPMs in China can lead to serious legal compliance problems. Thus, proper measures should be taken to remove these barriers. Starting with a complete view of the current legal obstacles to HPMs in China, this study first explains why these legal obstacles exist and the types of legal interests they are trying to protect. It then analyzes whether new technology could be used as an alternative to resolve these concerns. Factors such as national security, AD industry needs, and personal data protection, as well as the ?exibility of applying technology, are discussed and analyzed hierarchically for this purpose. This study proposes that China should adhere to national security and AD industry development, pass new technical regulations that redefine the scope of national security regarding geographic information in the field of HPMs, and establish a national platform under the guidance and monitoring of the government to integrate scattered resources and promote the development of HPMs via crowdsourcing. Regarding the legal obstacles with higher technical plasticity, priority should be given to technical solutions such as “available but invisible” technology. Compared with the previous research, this study reveals the current legal barriers in China that have different levels of relevance to national security and different technical plasticity. It also proposes original measures to remove them, such as coordinating national security with the development of the AD industry, reshaping the boundary of national security and industrial interests, and giving priority to technical solutions for legal barriers that have strong technical plasticity.
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    Lateral Force Characteristics of Cartridge Valve Core
    HAN Heyong1(韩贺永),ZHANG Jianru1(张建茹), PAN Siji1(潘思意),LI Yugui2*(李玉贵),MA Lifeng1(马立峰),LIU Shirui3(刘实睿)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 604-610.   DOI: 10.1007/s12204-021-2402-5
    Abstract31)      PDF (977KB)(15)      
    he valve core is readily subjected to a large lateral force which affects the dynamic response speed. Here, a new type of cartridge valve core structure is proposed to solve this problem. The numerical simulation method is applied to analyze the flow characteristics of clearance flow field on velocity distribution, pressure distribution, valve core motion speed, and leakage. The results using computational fluid dynamics (CFD) show that the guide groove is set on the surface of the cartridge valve core, increasing the connecting length of the valve core, forming a uniform radial pressure distribution and velocity distribution, effectively reducing the lateral force, and at the same time ensuring that the leak is not too big. These findings provide theoretical guidance and a basis for optimizing cartridge valve to reduce the occurrence of jamming and improve the response frequency.
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    Enhanced Tribological Performance of Diamond Films by Utilizing DLC and DLC-H Top Layers
    LBI Xuelin*(雷学林), YAN Ying (严莹),ZHANG Hang(张航),LI Zizruan (李子璇), HE Yun(何云)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 665-675.   DOI: 10.1007/s12204-021-2399-9
    Abstract20)      PDF (2266KB)(12)      
    High-performance diamond films are highly demanded on tool surfaces for wire-drawing and mechanical sealing applications. Herein, this work aims at enhancing the tribological performance of chemical vapor deposition diamond films in water-lubricated conditions by utilizing non-hydrogenated and hydrogenated diamond-like carbon (DLC and DLC-H) top layers. The tribological properties of bilayer micro-crystalline diamond (MCD)/DLC, MCD/DLC-H, nano-crystalline diamond (NCD)/DLC and NCD/DLC-H films are evaluated, in terms of maximal and stable coefficients of friction (COFs), C—C bonds transformation, worn surface morphology and specific wear rates. The results show that DLC or DLC-H coated on diamond layer significantly suppresses the initial maximal COF peak and the wear of counterpart ball. Moreover, severe regular arranged sp2 C—C bonds transformation is detected on MCD film, in comparison to NCD; while inversely, the NCD/DLC bilayer exhibits severer C—C bonds transformation effect compared with the MCD/DLC. Furthermore, the DLC-H top layer shows a larger decreasing rate of maximal COFs and wear rates of counterpart balls, compared with the DLC coating, which is due to its superior self-lubricity. Among all the tested films, the NCD/DLC-H bilayer shows an optimized tribological performance.
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    Regulation of Sleep Behavior by Overexpression of Amyloid Precursor Protein in Drosophila Neurons
    LI Minzhe (李慜哲), PING Yong (平勇)
    J Shanghai Jiaotong Univ Sci    2021, 26 (1): 63-68.   DOI: 10.1007/s12204-021-2261-0
    Abstract240)      PDF (462KB)(51)      
    Amyloid precursor protein (APP) can generate neurotoxic β-amyloid 42 (Aβ42) by proteolytic process, which plays a crucial role in the pathogenesis of Alzheimer’s disease (AD). Individuals with mild to moderate AD exhibit sleep disturbance, even before the onset of AD. The purpose of this study is to verify the effect of APP on sleep behavior by using an APP overexpressing Drosophila AD model. APP-overexpressed flies were grouped by age, and their sleep amounts were monitored. Our results demonstrated that APP overexpression had no impacts on sleep amounts in young (4—7 days after eclosion, 4—7AE) flies. However, APP overexpression contributed to lower day and total sleep amounts in the middle-aged (11—14AE) flies. Moreover, old-aged (40AE) flies with overexpressing APP exhibited increased number of sleep bouts and decreased sleep time, indicating sleep fragmentation in these flies. Our results indicated that overexpression of APP in neurons has distinct effects on sleep behavior at different ages, but the specific mechanisms underlying the sleep regulation by APP are needed for further study. In addition, our data also suggest that sleep disturbance in AD animals can be caused by APP expression alterations, which provide a potential treating target for sleep intervention and therapy for AD patients.

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    Stochastic Model Predictive Control Approach to Autonomous Vehicle Lane Keeping
    ZHANG Chenzhi (张晨之), ZHUANG Cheng (庄 诚), ZHENG Xueke (郑学科), CAI Runze (蔡润泽), LI Mian (李 冕)
    J Shanghai Jiaotong Univ Sci    2021, 26 (5): 626-633.   DOI: 10.1007/s12204-021-2352-y
    Abstract272)      PDF (702KB)(86)      
    In real-world scenarios, the uncertainty of measurements cannot be handled effciently by traditional model predictive control (MPC). A stochastic MPC (SMPC) method for handling the uncertainty of states in autonomous driving lane-keeping scenarios is presented in this paper. A probabilistic system is constructed by considering the variance of states. The probabilistic problem is then transformed into a solvable deterministic optimization problem in two steps. First, the cost function is separated into mean and variance components. The mean component is calculated online, whereas the variance component can be calculated offline. Second, Cantelli’s inequality is adopted for the deterministic reformulation of constraints. Consequently, the original probabilistic problem is transformed into a quadratic programming problem. To validate the feasibility and effectiveness of the proposed control method, we compared the SMPC controller with a traditional MPC controller in a lane-keeping scenario. The results demonstrate that the SMPC controller is more effective overall and produces smaller steady-state distance errors.
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    Multi-Object Tracking Strategy of Autonomous Vehicle Using Modified Unscented Kalman Filter and Reference Point Switching
    WANG Muyuan∗ (王木塬), WU Xiaodong (吴晓东)
    J Shanghai Jiaotong Univ Sci    2021, 26 (5): 607-614.   DOI: 10.1007/s12204-021-2350-0
    Abstract313)      PDF (1070KB)(102)      
    In this study, a multi-object tracking (MOT) scheme based on a light detection and ranging sensor was proposed to overcome imprecise velocity observations in object occlusion scenarios. By applying real-time velocity estimation, a modified unscented Kalman filter (UKF) was proposed for the state estimation of a target object. The proposed method can reduce the calculation cost by obviating unscented transformations. Additionally, combined with the advantages of a two-reference-point selection scheme based on a center point and a corner point, a reference point switching approach was introduced to improve tracking accuracy and consistency. The state estimation capability of the proposed UKF was verified by comparing it with the standard UKF in single-target tracking simulations. Moreover, the performance of the proposed MOT system was evaluated using real traffic datasets.
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    Effects of Micro-Milling and Laser Engraving on Processing Quality and Implantation Mechanics of PEG-Dexamethasone Coated Neural Probe
    ZHOU Xuhui (周旭辉), ZHANG Wenguang (张文光), XIE Jie (谢颉)
    J Shanghai Jiaotong Univ Sci    2021, 26 (1): 1-9.   DOI: 10.1007/s12204-020-2243-7
    Abstract444)      PDF (1890KB)(75)      
     Compared with stiff silicon-based probes, flexible neural probes can alleviate biological inflammation and tissue rejection. A polyethylene glycol (PEG) coating can facilitate the insertion of flexible probes, and the fabrication methods have a significant impact on the dimensional accuracy and structural strength of the coating. In this study, a novel melting injection moulding method is used to process a PEG-dexamethasone (PEG-DEX) coating with high structural strength for a type of mesh-shaped photosensitive polyimide (PSPI) based neural probe. Combined with the digital image correlation (DIC) method, an in vitro test system with high accuracy is developed to evaluate the effects of the elastic modulus of the PEG component and two fabrication methods, i.e., computer-numerical-control (CNC) micro-milling and laser engraving, on the processing quality and implantation mechanics of a PEG-DEX coated probe. The results show that compared with laser engraving, CNC micro-milling can ensure high dimensional accuracy and sharpness for the composite coating, thus leading to small damage from implantation, whereas the elastic modulus of the composite coating has a limited effect on the implantation mechanics of the PEG-DEX coated probe.

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    Active Disturbance Rejection Controller Based Heading Control of Underwater Flight Vehicles
    ZHENG Tianhai, FENG Zhengping, ZHAO Shuo, PAN Wanjun
    Journal of Shanghai Jiao Tong University(Science)    2020, 25 (4): 441-446.   DOI: 10.1007/s12204-020-2194-z
    Abstract477)      PDF (2251KB)(60)      
    The total disturbance estimated by the extended state observer (ESO) in active disturbance rejection
    controller (ADRC) is affected greatly by measurement noise when the control step is small in heading control
    of underwater flight vehicles (UFVs). In order to prevent rudder from high-frequency chattering caused by
    measurement noise, a tracking-differentiator (TD) is integrated to the ESO to develop an improved ADRC scheme.
    The improved ADRC suppresses the impact of sensor noise. Both the results of simulations and tank tests show
    the effectiveness of improved ADRC based heading control.
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    Spectrum-Sensing Method for Arc Fault Detection in Direct Current System with Lithium Batteries
    HAN Zhengqian1(韩正谦),LUO Liwenl*(罗利文),YAo Wei2(姚伟),YIN Shaowen2(尹邵文),CHEN Wei2(陈伟),WANG Yinghui2(王营辉)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 630-637.   DOI: 10.1007/s12204-022-2482-x
    Abstract23)      PDF (1295KB)(11)      
    We mainly study the detection of arc faults in the direct current (DC) system of lithium battery energy storage power station. Lithium battery DC systems are widely used, but traditional DC protection devices are unable to achieve adequate protection of equipment and circuits. We build an experimental platform based on an energy storage power station with lithium batteries. Then, the data collection of normal current and arc-fault current is completed under multiple conditions, and the waveforms of obvious and weak signals as the arc occurs are presented. We analyze the principles and application range of several common spectrum-sensing methods and study the feasibility of applying them to the arc detection field. Finally, the covariance absolute value detection algorithm is selected, and the average value of the current is filtered out to make the algorithm adapt to the arc detection field. The result shows that the detection probability in 500 sets of experimental data has reached 98%
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    Missile-Target Situation Assessment Model Based on Reinforcement Learning
    ZHANG Yun, Lü Runyan, CAI Yunze
    Journal of Shanghai Jiao Tong University(Science)    2020, 25 (5): 561-568.   DOI: 10.1007/s12204-020-2226-8
    Abstract592)      PDF (724KB)(40)      
    In situation assessment (SA) of missile versus target fighter, the traditional SA models generally
    have the characteristics of strong subjectivity and poor dynamic adaptability. This paper considers SA as an
    expectation of future returns and establishes a missile-target simulation battle model. The actor-critic (AC)
    algorithm in reinforcement learning (RL) is used to train the evaluation network, and a missile-target SA model
    is established in simulation battle training. Simulation and comparative experiments show that the model can
    effectively estimate the expected effect of missile attack under the current situation, and it provides an effective
    basis for missile attack decision.
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    Scaling Relation of the Scalar Diffusion in a Rotating Mixer
    SUN Na (孙娜), WANG Lipo (王利坡), LI Yuanbo (李渊博), LI Lin (李琳), QI Shuaipeng (齐帅鹏), SHEN Yongxing (沈泳星)
    J Shanghai Jiaotong Univ Sci    2021, 26 (2): 170-175.   DOI: 10.1007/s12204-021-2275-7
    Abstract395)      PDF (1495KB)(51)      
    Scalar mixing is under the joint control of convection and diffusion. The ratio of the dissipative scale of velocity field to that of the scalar field depends on the Schmidt number. In the high Schmidt number limit, the scalar scale is much smaller than that of the momentum, which then requires either special treatment or ad hoc models for the scalar quantity in numerical simulations. In order to avoid model uncertainty or unnecessary numerical complexity, the direct numerical simulation is performed for studying the scalar mixing process in a confined rotating mixer tank. It has been found that in the range of negligible numerical diffusivity,the characteristic scalar mixing time is inversely proportional to the scalar diffusivity. Analysis based on the dimensional argument justifies such scaling relation as well, from which the unaccepted computational time of the mixing process in the high Schmidt number limit can be efficiently determined, without the use of ad hoc models. This scaling idea is also of practical meaningfulness for other similar problems.
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    Prediction of Backfill Strength Based on Support Vector Regression Improved by Grey Wolf Optimization
    ZHANG Bo(张博),LI Keqing (李克庆),HU Yafei(胡亚飞),JI Kun(吉坤),HAN Bin*(韩斌)
    J Shanghai Jiaotong Univ Sci    2023, 28 (5): 686-694.   DOI: 10.1007/s12204-022-2408-7
    Abstract14)      PDF (881KB)(11)      
    In order to predict backfill strength rapidly with high accuracy and provide a new technical support for digitization and intelligentization of mine, a support vector regression (SVR) model improved by grey wolf optimization (GWO), GWO-SVR model, is established. First, GWO is used to optimize penalty term and kernel function parameter in SVR model with high accuracy based on the experimental data of uniaxial compressive strength of filling body. Subsequently, a prediction model which uses the best two parameters of best c and best g is established with the slurry density, cement dosage, ratio of artificial aggregate to tailings, and curing time taken as input factors, and uniaxial compressive strength of backfill as the output factor. The root mean square error of this GWO-SVR model in predicting backfill strength is 0.143 and the coefficient of determination is 0.983, which means that the predictive effect of this model is accurate and reliable. Compared with the original SVR model without the optimization of GWO and particle swam optimization (PSO)-SVR model, the performance of GWO-SVR model is greatly promoted. The establishment of GWO-SVR model provides a new tool for predicting backfill strength scientifically.
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    Numerical Study of Sodium Bentonite Extrusion into a Planar Fracture
    LIU Miaomiao (刘苗苗), LI Xiaoyue (李晓月), XU Yongfu (徐永福)
    J Shanghai Jiaotong Univ Sci    2021, 26 (2): 146-154.   DOI: 10.1007/s12204-021-2268-6
    Abstract299)      PDF (940KB)(129)      
     As a candidate buffer/backfill material for high-level radioactive waste geological repositories, bentonite has numerous favorable properties, such as low permeability, high expansibility, and a high sorption capacity for radionuclides. The radionuclide-isolating performance of a buffer is strongly influenced by its extrusion. In this study, the bentonite extrusion process is explored: its basic mechanism can be considered free swelling of the bentonite. A 2D extrusion model of bentonite that is based on the 1D free swelling model of bentonite is presented. A numerical method is proposed to investigate the extrusion process of Na-bentonite into fractures over time under no-seepage conditions based on the free swelling model. The influences of the electrolyte concentration and dry density on the extrusion depth and mass of the bentonite are discussed, and the distribution of montmorillonite inside the bentonite is analysed. The rationale of the proposed bentonite extrusion model is then illustrated in comparison with the results of the bentonite extrusion test.
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