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Modern data sources and techniques for analysis and forecast of road accidents:A review

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Journal of Traffic and Transportation Engineering(English Edition) 2020年第4期7卷 432-446页

作者： Camilo gutierrez-Osorio Cesar Pedraza Departamento de Ingeniena de Sistemas e Industrial Universidad Nacional de ColombiaBogotaColombia

Road accidents are one of the most relevant causes of injuries and death worldwide,and therefore,they constitute a significant field of research on the use of advanced algorithms and techniques to analyze and predict traffic accidents and determine the most relevant elements that contribute to road *** research of road accident prediction aims to respond to the challenge of offer tools to generate a more secure mobility environment,and ultimately,save *** paper aims to provide an overview of the state of the art in the prediction of road accidents through machine learning algorithms and advanced techniques for analyzing information,such as convolutional neural networks and long short-term memory networks,among other deep learning ***,in this article,a compendium and study of the most used data sources for the road accident forecast is *** a classification is proposed according to its origin and characteristics,such as open data,measurement technologies,onboard equipment and social media *** the analysis of the information,the different algorithms employed to make predictions about road accidents are listed and compared,as well as their applicability depending on the types of data being analyzed,along with the results obtained and their ease of interpretation and *** best results reported by the authors are obtained when two or more analytic techniques are combined,in such a way that analysis of the obtained results is *** the future challenges in road traffic forecasting lies the enhancement of the scope of the proposed models and predictions by the incorporation of heterogeneous data sources,that include geo spatial data,information from traffic volume,traffic statistics,video,sound,text and sentiment from social media,that many authors concur that can improve the precision and accuracy of the analysis and predictions.

关键词： Traffic engineering Data analysis Machine learning Road accident forecasting Traffic accident prediction

Gastric cancer research in Mexico:A public health priority

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World Journal of Gastroenterology 2014年第16期20卷 4491-4502页

作者： Clara Luz Sampieri mauricio Mora Instituto de Salud Pública Universidad VeracruzanaAv. Luis Castelazo AyalaCol. Industrial ánimas91190 XalapaVeracruzMéxico Facultad de Medicina Universidad Veracruzana.Médicos y OdontólogosCol. Virginia Cordero91120 XalapaVeracruzMéxico

This study aimed review studies conducted on Mexican patients diagnosed with gastric cancer and/or diseases associated with its development,in which at least one Mexican institute has participated,and to assess their contributions to the primary and secondary prevention of this disease.A search of the Medline database was conducted using the following keywords:gastric/stomach cancer,*** of the Mexican population were selected in which at least one Mexican Institute had participated and where the findings could support public policy proposals directed towards the primary or secondary prevention of gastric *** the148 studies found in the Medline database,100 were discarded and 48 were *** to the analysis presented,these studies were classified as:epidemiology of gastric cancer(5/48);risk factors and protectors relating to gastric cancer(9/48);relationship between Helicobacter pylori and pathologies associated with gastric cancer and the development of the disease(16/48);relationship between the Epstein-Barr virus and pathologies associated with gastric cancer and the development of the disease(3/48);molecular markers for the development of diseases associated with gastric cancer and gastric cancer(15/48).Mexico requires a program for the prevention and control of gastric cancer based on national health *** should be produced by a multidisciplinary committee of experts who can propose actions that are relevant in the current national *** few studies of gastric cancer conducted on the Mexican population in national institutes highlight the poor connection that currently exists between the scientific community and the health sector in terms of resolving this health *** policies for health research should support projects with findings that can be translated into benefits for the *** review serves to identify national research groups studying gastric cancer in the Mexican population.

关键词： Gastric cancer Mexico Research Prevention Public health

Virtual Conductance Based Cascade Voltage Controller for VSCs in Islanded Operation Mode

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1704-1713页

作者： Francisco Jesús Matas-Díaz Manuel Barragán-Villarejo Juan Carlos Olives-Camps Juan Manuel mauricio JoséMaría Maza-Ortega Department of Elec‐trical Engineering Universidad de SevillaSeville 41092Spain

Voltage source converters have become the main enabler for the integration of distributed energy resources in *** the case of islanded operation,these devices normally set the amplitude and frequency of the network voltage by means of a cascade controller composed of an outer voltage control loop and an inner current control *** strategies to compute the gains of both control loops have been proposed in the literature in order to obtain a fast and decoupled response of the voltages at the point of common *** paper proposes an alternative and simple methodology based on the introduction of a virtual conductance in the classic cascade *** strategy allows to design each control loop independently,obtaining a closed-loop response of a first-order *** this way,the gains of each control loop are easily derived from the parameters of the LC coupling filter and the desired closed-loop time ***,a state observer is included in the controller to estimate the inductor current of the LC filter in order to reduce the number of required measurements.A laboratory testbed is used to validate and compare the proposed *** experimental results demonstrate the effectiveness of the proposal both in steady-state and transient regimes.

关键词： Voltage source converter microgrid cascade controller virtual conductance

Effect of surface loading on the hydro-mechanical response of a tunnel in saturated ground

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Underground Space 2016年第1期1卷 1-19页

作者： Simon Heru Prassetyo Marte gutierrez Department of Civil and Environmental Engineering Colorado School of MinesGoldenCO 80401USA

The design of underground spaces in urban areas must account not only for the current overburden load but also for future surface loads,such as from construction of high-rise buildings above underground *** saturated ground,the surface load will generate an additional mechanical response through stress changes and ground displacement,as well as a hydraulic response through pore pressure *** hydro-mechanical(H-M)changes can severely influence tunnel *** paper examines the effect of surface loading on the H-M response of a typical horseshoe-shaped tunnel in saturated *** tunnel models were created in the computer code Fast Lagrangian Analysis of Continua(FLAC).One model represented weak and low permeability ground(stiff clay),and the other represented strong and high permeability ground(weathered granite).Each of the models was run under two liner permeabilities:permeable and *** main cases were *** Case 1,the surface load was applied 10 years after tunnel *** Case 2,the surface load was applied after the steady state pore pressure condition was *** simulation results show that tunnels with impermeable liners experienced the most severe influence from the surface loading,with high pore pressures,large inward displacement around the tunnels,and high bending moments in the *** addition,the severity of the response increased toward steady *** induced H-M response was worse for tunnels in clay than for those in ***,the long-term liner stabilities in Case 1 and Case 2 were similar,indicating that the influence of the length of time between when the tunnel was completed and when the surface load was applied was *** findings suggest that under surface loading,in addition to the ground strength,tunnel stability in saturated ground is largely influenced by liner permeability and the long-term H-M response of the ground.

关键词： Surface loading Hydro-mechanical response Urban tunnels Saturated ground

Axisymmetric alternating direction explicit scheme for efficient coupled simulation of hydro-mechanical interaction in geotechnical engineering-Application to circular footing and deep tunnel in saturated ground

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 259-279页

作者： Simon Heru Prassetyo Marte gutierrez Department of Civil and Environmental Engineering Colorado School of MinesGoldenUSA Mining Engineering Program Institut Teknologi BandungBandungIndonesia

Explicit solution techniques have been widely used in geotechnical engineering for simulating the coupled hydro-mechanical(H-M) interaction of fluid flow and deformation induced by structures built above and under saturated ground, i.e. circular footing and deep tunnel. However, the technique is only conditionally stable and requires small time steps, portending its inefficiency for simulating large-scale H-M problems. To improve its efficiency, the unconditionally stable alternating direction explicit(ADE)scheme could be used to solve the flow problem. The standard ADE scheme, however, is only moderately accurate and is restricted to uniform grids and plane strain flow conditions. This paper aims to remove these drawbacks by developing a novel high-order ADE scheme capable of solving flow problems in nonuniform grids and under axisymmetric conditions. The new scheme is derived by performing a fourthorder finite difference(FD) approximation to the spatial derivatives of the axisymmetric fluid-diffusion equation in a non-uniform grid configuration. The implicit Crank-nicolson technique is then applied to the resulting approximation, and the subsequent equation is split into two alternating direction sweeps,giving rise to a new axisymmetric ADE scheme. The pore pressure solutions from the new scheme are then sequentially coupled with an existing geomechanical simulator in the computer code fast Lagrangian analysis of continua(FLAC). This coupling procedure is called the sequentially-explicit coupling technique based on the fourth-order axisymmetric ADE scheme or SEA-4-AXI. Application of SEA-4-AXI for solving axisymmetric consolidation of a circular footing and of advancing tunnel in deep saturated ground shows that SEA-4-AXI reduces computer runtime up to 42%-50% that of FLAC’s basic scheme without numerical instability. In addition, it produces high numerical accuracy of the H-M solutions with average percentage difference of only 0.5%-1.8%.

关键词： Hydro-mechanical(H-M) interaction Explicit coupling technique Alternating direction explicit(ADE) scheme High-order finite difference(FD) non-uniform grid Axisymmetric consolidation Circular footing Deep tunnel in saturated ground

UnCOnDITIOnAL CAUCHY SERIES AnD UnIFORM COnVERGEnCE On MATRICES

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Chinese Annals of Mathematics,Series B 2004年第3期25卷 335-346页

作者： A.AIZPURU A.gutierrez-DAVILA DepartarnentodeMatematicas UniversidaddeCadizApdo.4011510-PuertoReal（Cadiz）Spain DepartamentodeMatematicas UniversidaddeCadizApdo.4011510-PuertoReal（Cadiz）Spain

The authors obtain new characterizations of unconditional Cauchy series in terms of separation properties of subfamilies of p(n), and a generalization of the Orlicz-Pettis Theorem is also obtained. new results on the uniform convergence on matrices and a new version of the Hahn-Schur summation theorem are proved. For matrices whose rows define unconditional Cauchy series, a better sufficient condition for the basic Matrix Theorem of Antosik and Swartz, new necessary conditions and a new proof of that theorem are given.

关键词： Unconditional Cauchy series Orlicz-Pettis theorem Summation Hahn-Schur theorem Basic matrix theorem

Effectiveness of predicting tunneling-induced ground settlements using machine learning methods with small datasets

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第4期14卷 1028-1041页

作者： Linan Liu Wendy Zhou Marte gutierrez Department of Geology and Geological Engineering Colorado School of MinesGoldenCO80401USA Department of Civil and Environmental Engineering Colorado School of MinesGoldenCO80401USA

Prediction of tunneling-induced ground settlements is an essential task,particularly for tunneling in urban *** settlements should be limited within a tolerable threshold to avoid damages to aboveground *** learning(ML)methods are becoming popular in many fields,including tunneling and underground excavations,as a powerful learning and predicting ***,the available datasets collected from a tunneling project are usually small from the perspective of applying ML *** ML algorithms effectively predict tunneling-induced ground settlements when the available datasets are small?In this study,seven ML methods are utilized to predict tunneling-induced ground settlement using 14 contributing factors measured before or during tunnel *** methods include multiple linear regression(MLR),decision tree(DT),random forest(RF),gradient boosting(GB),support vector regression(SVR),back-propagation neural network(BPnn),and permutation importancebased BPnn(PI-BPnn)*** methods except BPnn and PI-BPnn are shallow-structure ML *** effectiveness of these seven ML approaches on small datasets is evaluated using model accuracy and *** model accuracy is measured by the coefficient of determination(R2)of training and testing datasets,and the stability of a learning algorithm indicates robust predictive ***,the quantile error(QE)criterion is introduced to assess model predictive performance considering underpredictions and *** study reveals that the RF algorithm outperforms all the other models with the highest model prediction accuracy(0.9)and stability(3.0210^(-27)).Deep-structure ML models do not perform well for small datasets with relatively low model accuracy(0.59)and stability(5.76).The PI-BPnn architecture is proposed and designed for small datasets,showing better performance than typical *** important contributing factors of ground settlements are identified,including

关键词： Ground settlements Tunneling Machine learning Small dataset Model accuracy Model stability Feature importance

Physical model simulation of rock-support interaction for the tunnel in squeezing ground

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 82-92页

作者： Ketan Arora Marte gutierrez Ahmadreza Hedayat Civil and Environmental Engineering Colorado School of MinesGoldenCO80401USA

The existence of squeezing ground conditions can lead to significant challenges in designing an adequate support system for *** empirical,observational and analytical methods have been suggested over the years to design support systems in squeezing ground conditions,but all of them have some *** this study,a novel experimental setup having physical model for simulating the tunnel boring machine(TBM)excavation and support installation process in squeezing clay-rich rocks is *** observations are made to understand better the interaction between the support and the squeezing *** physical model included a large true-triaxial cell,a miniature TBM,laboratoryprepared synthetic test specimen with properties similar to natural mudstone,and an instrumented cylindrical aluminum support *** were conducted at realistic in situ stress levels to study the time-dependent three-dimensional tunnel support *** tunnel was excavated using the miniature TBM in the cubical rock specimen loaded in the true-triaxial cell,after which the support was *** confining stress was then increased in stages to values greater than the rock’s unconfined compressive strength.A model for the time-dependent longitudinal displacement profile(LDP)for the supported tunnel was proposed using the tunnel convergence measurements at different times and stress *** LDP formulation was then compared with the unsupported model to calculate the squeezing amount carried by the *** increase in thrust in the support was backcalculated from an analytical solution with the assumption of linear elastic *** on the test results and case studies,a recommendation to optimize the support requirement for tunnels in squeezing ground is proposed.

关键词： Squeezing ground Tunnel support system Longitudinal displacement profile Rock-support interaction

Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte gutierrez Zhiwei Yan Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University Transportation Center for Underground Transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock