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Determining the road traffic accident hotspots using GIS-based temporal-spatial statistical analytic techniques in Hanoi,Vietnam

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Geo-Spatial Information Science 2020年第2期23卷 153-164页

作者： Khanh Giang Le Pei Liu Liang-Tay lin College of Construction and Development Feng Chia UniversityTaichungTaiwanChina Faculty of Civil Engineering University of Transport and CommunicationsHanoiVietnam

This study applied GIS-based statistical analytic techniques to investigate the influence of accident Severity Index(SI)on temporal-spatial patterns of accident hotspots related to the specific time intervals of day and seasons.Road Traffic Accident(RTA)data in 3 years(2015-2017)in Hanoi,Vietnam were used to analyze and test this approach.Firstly,the RTA data were divided into four seasons in accordance with Hanoi's weather conditions and the time intervals such as the daytime,nighttime,or peak hours.Then,the Kernel Density Estimation(KDE)method was applied to analyze hotspots according to the time intervals and seasons.Finally,the results were presented by using the comap technique.This study considered both analyses with and without SI.The accident SI measures the seriousness of an accident.The approach method is to give higher weights to the more serious accidents,but not with the extremely high values calculated on a direct rate to the accident expenditures.The results showed that both analyses determined the relatively similar hotspots,but the rankings of some hotspots were quite different due to the integration of SI.It is better to take into account SI in determining RTA hotspots because the gained results are more precise and the rankings of hotspots are more accurate.From there,the traffic authorities can easily understand the causes behind each accident and provide reasonable solutions to solve the most dangerous hotspots in case of limited budget and resources appropriately.This is also the first study about this issue in Vietnam,so the contribution of the article will help the traffic authorities easily solve this problem not only in Hanoi but also in other cities.

关键词： Road Traffic Accident(RTA) hotspot GIS temporal-spatial analysis Kernel Density Estimation(KDE) Severity Index(SI)

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Optimal preparation of high-entropy boride-silicon carbide ceramics

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Journal of Advanced Ceramics 2021年第1期10卷 173-180页

作者： Yan ZHANG Shi-Kuan SUN Wei-Ming GUO liang XU Wei ZHANG Hua-tay lin School of Electron-mechanical Engineering Guangdong University of TechnologyGuangzhou 510006China Department of Materials Science and Engineering University of SheffieldSheffield SI 3JDUK

High-entropy boride-silicon carbide(HEB-SiC)ceramics were fabricated using boridebased powders prepared from borothermal and boro/carbothermal reduction methods.The effects of processing routes(borothermal reduction and boro/carbothermal reduction)on the HEB powders were examined.HEB-SiC ceramics with>98%theoretical density were prepared by spark plasma sintering at 2000℃.It was demonstrated that the addition of SiC led to slight coarsening of the microstructure.The HEB-SiC ceramics prepared from boro/carbothermal reduction powders showed a fine-grained microstructure and higher Vickers9 hardness but lower fracture toughness value as compared with the same composition prepared from borothermal reduction powders.These results indicated that the selection of the powder processing method and the addition of SiC phase could contribute to the optimal preparation of high-entropy boride-based ceramics.

关键词： high-entropy boride-silicon ceramics borothermal reduction boro/carbothermal reduction microstructure mechanical properties

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Low-temperature densification of high-entropy(Ti,Zr,Nb,Ta,Mo)C-Co composites with high hardness and high toughness

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Journal of Advanced Ceramics 2022年第5期11卷 805-813页

作者： Si-Chun LUO Wei-Ming GUO Kevin PLUCKNETT Hua-tay lin School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China School of Mechanical and Electronic Engineering Pingxiang UniversityPingxiang 337000China Department of Process Engineering and Applied Science Dalhousie UniversityHalifax B3J1ZICanada

In order to prepare high toughness(Ti,Zr,Nb,Ta,Mo)C ceramics at low temperatures while maintaining high hardness,a liquid-phase sintering process combined with Co-based liquid-phase extrusion strategy was adopted in this study.The densification temperature can be lowered to 1350℃,which is much lower than the solid-state sintering temperature(~2000℃)generally employed for high-entropy carbide ceramics.When sintered at 1550℃and 30 MPa applied pressure,part of the Co-based liquid-phase was squeezed out of the graphite mold,such that only~3.21 vol%of Co remained in the high-entropy ceramic.Compared to the Co-free solid-state sintered(Ti,Zr,Nb,Ta,Mo)C ceramics,prepared at 2000℃and 35 MPa,the hardness was slightly decreased from 25.06±0.32 to 24.11±0.75 GPa,but the toughness was increased from 2.25±0.22 to 4.07±0.13 MPa·m^(1/2).This work provides a new strategy for low-temperature densification of high-entropy carbides with both high hardness and high toughness.

关键词： high-entropy carbide ceramics liquid-phase sintering microstructure grain size mechanical properties

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Multi-Distributed Speech Emotion Recognition Based on Mel Frequency Cepstogram and Parameter Transfer

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Chinese Journal of Electronics 2022年第1期31卷 155-167页

作者： lin Long TAN liang School of Computer Science Sichuan Normal University Institute of Computing Technology Chinese Academy of Sciences

Speech emotion recognition(SER) is the use of speech signals to estimate the state of emotion. At present, machine learning is one of the main research methods of SER, the test and training data S of traditional machine learning all have the same distribution and feature space, but the data of speech is accessed from different environments and devices, with different distribution characteristics in real life. Thus, the traditional machine learning method is applied to the poor performance of SER. This paper proposes a multi-distributed SER method based on Mel frequency cepstogram(MFCC) and parameter transfer. The method is based on single-layer long short-term memory(LSTM), pre-trained inceptionv3 network and multi-distribution corpus. The speech pre-processed MFCC is taken as the input of single-layer LSTM, and input to the pre-trained inception-v3 network.The features are extracted through the pre-trained inception-v3 model. Then the features are sent to the newly defined the fully connected layer and classification layer,let the parameters of the fully connected layer be finetuned, finally get the classification result. The experiment proves that the method can effectively complete the classification of multi-distribution speech emotions and is more effective than the traditional machine learning framework of SER.

关键词： Speech emotion recognition (SER) Machine learning Mel frequency cepstogram (MFCC) Parameter transfer Long short-term memory (LSTM) Inception-v3

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Analysis and experimental study on resistance-increasing behavior of composite high efficiency autonomous inflow control device

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PETROLEUM SCIENCE 2024年第2期21卷 1290-1304页

作者： Dong, liang-liang Zhang, Yu-lin Southwest Petr Univ Sch Mechatron Engn Chengdu 610500 Sichuan Peoples R China Southwest Petr Univ State Key Lab Oil & Gas Reservoir Geol & Exploitat Chengdu 610500 Sichuan Peoples R China Oil & Gas Equipment Technol Sharing & Serv Platfor Chengdu 610500 Sichuan Peoples R China

Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device (AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production. After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that, compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content, the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production. (c) 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/ 4.0/).

关键词： Water control Flow separation Flow resistance-increasing AICD device Simulation and experiment DESIGN

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A Bond Pricing Model with Credit Migration Risk:Different Upgrade and Downgrade Thresholds

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Acta Mathematicae Applicatae Sinica 2023年第3期39卷 765-777页

作者： Jin liang Yang lin School of Mathematical Sciences Tongji UniversityShanghai 200092China

In this paper, a new corporate bond pricing model with credit migration risk is proposed. This model sets different thresholds for the rising or falling of credit ratings, which forms a buffer zone that could reduce the frequency of credit rating changes. Mathematically, this model is a system of partial differential equations with overlapping area. The existence, uniqueness, regularity and asymptotic behavior of the solution are obtained. Furthermore, a numerical scheme and its stability, convergence and accuracy are discussed in detail. Calibration and analysis of the parameters are also suggested.

关键词： credit migration risk corporate bond pricing structural model buffer zone monotonic iteration calibration

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Design strategy of phase and microstructure of Si_(3)N_(4) ceramics with simultaneously high hardness and toughness

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Journal of Advanced Ceramics 2023年第1期12卷 122-131页

作者： Shao-Jun TANG Wei-Ming GUO Shi-Kuan SUN Hua-tay lin School of Electromechanical Engineering Guangdong University of TechnologyGuangzhou 510006China School of Material Science and Energy Engineering Foshan UniversityFoshan 528000China

Aiming to achieve silicon nitride( Si_(3)N_(4))ceramics with high hardness and high toughness,the relationships among phase composition,microstructure,and mechanical properties of Si_(3)N_(4) ceramics prepared by spark plasma sintering(SPS)at temperatures ranging from 1500 to 1800℃were investigated in this study.Two stages with different phase and microstructure features were observed and summarized.Theα-βphase transformation occurs first,and the development and growth of grains lag behind.During the first stage,the average grain size remains basically unchanged,and the hardness maintains at a value of~20.18±0.26 GPa,despite theβ- Si_(3)N_(4) phase fraction increases from 7.67 to 57.34 wt%.Subsequently,the equiaxed grains transform into rod-like grains with a high aspect ratio via the reprecipitation process,resulting in a significant increase in the fracture toughness from 3.36±0.62 to 7.11±0.15 MPa·m^(1/2).In the second stage of sintering process,the fraction ofβ- Si_(3)N_(4) phase increases to 100.00 wt%,and the grain growth also rapidly occurs.Thus,the fracture toughness increases slightly to 7.61±0.42 MPa·m^(1/2),but the hardness reduces to 16.80±0.20 GPa.The current results demonstrate that the phase contents ofβ- Si_(3)N_(4) and the microstructure shall be carefully tailored to achieve high-performance Si_(3)N_(4) ceramics. Si_(3)N_(4) ceramics with a finegrained bimodal microstructure,consisting of the mainα-andβ-phases,can exhibit the optimized combination of hardness and toughness.

关键词： silicon nitride(Si_(3)N_(4)) phase composition microstructure hardness toughness

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Design Method of Reversely Switched Dynistor Based Pulse Circuit Without Magnetic Switch

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CSEE Journal of Power and Energy Systems 2023年第1期9卷 306-314页

作者： Yicheng Pi lin liang Xiaoxue Yan State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In the reversely switched dynistor(RSD)-based pulse power circuits,a magnetic switch is usually necessary to be applied together with a main switch.It occupies space and needs a magnetic reset.In this paper,a method of designing a RSD-based pulse circuit without a magnetic switch is proposed.In the pulse circuit,a RBDT(reverse blocking diode thyristor)is used to separate the two capacitors and provide an energy branch.The pre-charge time of the RSD can be guaranteed by the energy conversion between the capacitors and inductors,instead of the saturation of the magnetic switch.In addition,the energy which is reused to trigger the RSD is based on an inductor.The pulse circuit is evaluated by simulations and practical experiments.According to the experimental results,the factors affecting the load pulse current and triggering of the RSD and RBDT are studied.Meanwhile,a method to reduce the current in the trigger switch,which is a potential problem in the pulse circuit,is proposed.

关键词： Magnetic switch pulse power circuit reversely switched dynistor(RSD) reverse blocking diode thyristor(RBDT)

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Updates on hepatitis E virus

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Chinese Medical Journal 2022年第10期135卷 1231-1233页

作者： Zhaochao liang lin Wang ling Wang Department of Microbiology and Infectious Disease Centre School of Basic Medical SciencesPeking University Health Science CentreBeijing 100191China

Hepatitis E virus(HEV)is the causative agent of hepatitis E.Globally,it is estimated that 20 milion HEV infections with 3.3 million symptomatic cases occur annully,and the mortality rate is 0.5%to 3%in general population.Although hepatitis E is commonly considered as an acute,self-limited disease,HEV_infection can be chronic in immunocompromised patients and related,with high mortality rate and poor pregnancy outcomes in pregnant women.

关键词： mortality hepatitis acute

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Experimental investigation on the distribution uniformity and pressure drop of perforated plate distributors for the innovative spray-type packed bed thermal storage

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Particuology 2022年第2期20卷 60-73页

作者： lin lin liang Wang Xipeng lin Ningning Xie Haisheng Chen Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalian 116023China National Energy Large Scale Physical Energy Storage Technologies R&D Center of Bijie High-tech Industrial Development Zone Guizhou 551712China Institute of Science and Technology China Three Gorges CorporationBeijing 100038China

As an innovative thermal energy technology,the spray-type packed bed has advantages of high efficiency and low cost.A liquid distributor is the key component for the spray-type packed bed for scattering heat-transfer liquid drops evenly.In this study,the distribution performance and pressure drop of the perforated plate distributors of different orifice diameters were studied experimentally.The experimental results indicate that orifice diameter has a greater effect on the distribution performance compared to flow rate.With an increase in flow rate,the flow pattern through the distributor changes from the uncovered drop to the covered drop and then to the jet flow.The covered drop pattern shows the best performance with a good distribution and a small pressure drop simultaneously,which is the design and optimization principle of the distributor for a spray-type packed bed.

关键词： Spray-type packed bed Perforated plate distributor Distribution Pressure drop Thermal energy storage

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