Fatigue analysis of catenary contact wires for high speed trains

The fatigue fracture is one of the most critical failures which may occur on the high speed network because it is undetectable and it has a huge impact on traffic disruption. The contact wire lifespan of a high speed line is estimated at more than 50 years and thus it is necessary to consider the risk of fatigue. The Railway Technical Research Institute in Japan studied this phenomenon for a long time and performed experimental tests. Using these results and by comparing with failures occurred in France, a preliminary analysis is carried out to identify parameters which significantly influence the fatigue phenomenon. This analysis consists in using the numerical software OSCAR© to evaluate the loads, perform a fatigue assessment of the contact wire. The procedure, using a one-dimensional and a three-dimensional model, is described in this article

Approach for GDPR Compliant Detection of COVID-19 Infection Chains

While prospect of tracking mobile devices' users is widely discussed all over European countries to counteract COVID-19 propagation, we propose a Bloom filter based construction providing users' location privacy and preventing mass surveillance. We apply a solution based on Bloom filters data structure that allows a third party, a government agency, to perform some privacy-preserving set relations on a mobile telco's access logfile. By computing set relations, the government agency, given the knowledge of two identified persons, has an instrument that provides a (possible) infection chain from the initial to the final infected user no matter at which location on a worldwide scale they are. The benefit of our approach is that intermediate possible infected users can be identified and subsequently contacted by the agency. With such approach, we state that solely identities of possible infected users will be revealed and location privacy of others will be preserved. To this extent, it meets General Data Protection Regulation (GDPR)requirements in this area

Allocation conjointe de puissance et rendement d'un utilisateur cognitif exploitant les retransmissions d'un utilisateur primaire : le cas du canal en Z

National audienceDans cet article, nous considérons le problème de l’allocation conjointe de puissance et de rendement pour un utilisateur secondaire exploitant le protocole de retransmission d’un utilisateur primaire. Nous proposons un algorithme, basé sur les Processus de Markov Décisionnels (MDP), permettant de calculer une allocation optimale pour le problème de la maximisation du débit de l’utilisateur secondaire tout en garantissant un débit minimal pour l’utilisateur primaire

Opportunistic Secondary Spectrum Sharing Protocols for Primary implementing an IR type Hybrid-ARQ Protocol

In this paper, we propose, analyze and compare three different methods for opportunistic spectrum sharing access when the primary users implements an Incremental Redundancy (IR) type Hybrid Automatic ReQuest (H-ARQ) protocol. The first method consists in allowing the secondary user to communicate only during the first primary transmission round of the IR H-ARQ protocol. In this scenario, if the the secondary receiver fails to decode its message after the first round, it realizes a successive interference cancellation in the subsequent primary HARQ rounds by listening to the primary user. The second method consists in realizing a perfect interference cancellation at the secondary receiver with causal channel state information. In this method, the secondary user communicates only when the secondary receiver succeeds in decoding the primary message.To improve throughput performance at the secondary, the secondary pair is also considering the use of an IR-HARQ protocol. In a third method, the secondary user communicates following the same rule as in the proposed second method, but implementing an Adaptive Modulation and Coding scheme instead of HARQ. In particular, we show that this last protocol with a small number of interfered slots allows to limit the loss in the primary throughput needed for the secondary user to transmit

Performance of a Serial-Batch Processor System with Incompatible Job Families under Simple Control Policies

A typical example of a batch processor is the diffusion furnace used in wafer fabrication facilities (otherwise known as wafer fabs). In diffusion, silicon wafers are placed inside the furnace, and dopant is flown through the wafers via nitrogen gas. The higher the temperature, the faster the dopant penetrates the wafer surface. Then, a thin layer of silicon dioxide is grown, to help the dopant diffuse into the silicon. This operation can take 10 hours or more to finish processing, as compared to one or two hours for other wafer fab operations, according to Uzsoy [8]. Diffusion furnaces typically can process six to eight lots concurrently; we call the lots processed concurrently a batch. The quantity of lots loaded into the furnace does not affect the processing time. Only lots that require the same chemical recipe and temperature may be batched together at the diffusion furnace. We wish to control the production of a manufacturing system, comprised of a serial processor feeding the batch processor. The system produces different job types, and each job can only be batched together with jobs of the same type. More specifically, we explore the idea of controlling the production of the serial processor, based on the wip found in front of the batch processor. We evaluate the performance of our manufacturing system under several simple control policies under a range of loading conditions and determine which control policies perform better under which conditions. It is hoped that the results obtained from this small system could be extended to larger systems involving a batch processor, with particular emphasis placed on the applicability of such policies in wafer fabrication.Singapore-MIT Alliance (SMA

Implementation of ISO/IEC 17025:2017 as a requirement to obtain ICA registration: case study

Los laboratorios de análisis y diagnóstico veterinario con prestación de servicios a terceros del departamento de Córdoba que buscan aprovechar la oportunidad de ampliar la cobertura y mejorar la prestación de los servicios de protección a la producción pecuaria deben contar con registro ICA el cual dentro de sus requisitos exige la implementación de la norma ISO/IEC 17025:2017. En este orden de ideas, se realizó un diagnóstico al laboratorio clínico veterinario del caso de estudio a través de la aplicación de listas de chequeo y una entrevista realizada a la gerente con el fin de conocer el grado de cumplimiento de los requisitos para la obtención de registro ICA, además, se evaluaron las condiciones actuales por medio de un análisis DOFA con el fin de conocer estrategias que puedan ser útiles para el proceso. Por último, se evidenció la importancia de la futura implantación de la norma para la obtención del registro ICA, concluyendo que este sistema de gestión establece un esquema de mejoramiento continuo que permita ampliar el reconocimiento y la confiabilidad de los laboratorios.Veterinary analysis and diagnostic laboratories providing services to third parties in the department of Córdoba that seek to take advantage of the opportunity to expand coverage and improve the provision of services for the protection of livestock production must have ICA registration, which among its requirements demands the implementation of the ISO/IEC 17025:2017 standard. In this order of ideas, a diagnosis was made to the clinical veterinary laboratory of the case study through the application of checklists and an interview with the manager in order to know the degree of compliance with the requirements for obtaining ICA registration, in addition, the current conditions were evaluated by means of a SWOT analysis in order to know strategies that may be useful for the process. Finally, the importance of the future implementation of the standard for obtaining the ICA registration was evidenced, concluding that this management system establishes a scheme of continuous improvement that allows to increase the recognition and reliability of the laboratories.Especializació

Probabilistic simulation for the certification of railway vehicles

The present dynamic certification process that is based on experiments has been essentially built on the basis of experience. The introduction of simulation techniques into this process would be of great interest. However, an accurate simulation of complex, nonlinear systems is a difficult task, in particular when rare events (for example, unstable behaviour) are considered. After analysing the system and the currently utilized procedure, this paper proposes a method to achieve, in some particular cases, a simulation-based certification. It focuses on the need for precise and representative excitations (running conditions) and on their variable nature. A probabilistic approach is therefore proposed and illustrated using an example. First, this paper presents a short description of the vehicle / track system and of the experimental procedure. The proposed simulation process is then described. The requirement to analyse a set of running conditions that is at least as large as the one tested experimentally is explained. In the third section, a sensitivity analysis to determine the most influential parameters of the system is reported. Finally, the proposed method is summarized and an application is presented

Fatigue analysis of catenary contact wires for high speed trains

The fatigue fracture is one of the most critical failures which may occur on the high speed network because it is undetectable and it has a huge impact on traffic disruption. The contact wire lifespan of a high speed line is estimated at more than 50 years and thus it is necessary to consider the risk of fatigue. The Railway Technical Research Institute in Japan studied this phenomenon for a long time and performed experimental tests. Using these results and by comparing with failures occurred in France, a preliminary analysis is carried out to identify parameters which significantly influence the fatigue phenomenon. This analysis consists in using the numerical software OSCAR© to evaluate the loads, perform a fatigue assessment of the contact wire. The procedure, using a one-dimensional and a three-dimensional model, is described in this article

Control of Job Arrivals with Processing Time Windows into Batch Processor Buffer

Consider a two-stage manufacturing system composed of a batch processor and its upstream feeder processor. Jobs exit the feeder processor and join a queue in front of the batch processor, where they wait to be processed. The batch processor has a finite capacity Q, and the processing time is independent of the number of jobs loaded into the batch processor. In certain manufacturing systems (including semiconductor wafer fabrication), a processing time window exists from the time the job exits the feeder processor till the time it enters the batch processor. If the batch processor has not started processing a job within the job’s processing time window, the job cannot proceed without undergoing rework or validation by process engineers. We generalize this scenario by assigning a reward R for each successfully processed job by the feeder processor, and a cost C for each job that exceeds its processing time window without being processed by the batch processor. We examine a problem where the feeder processor has a deterministic processing time and the batch processor has stochastic processing time, and determine that the optimal control policy at the feeder processor is insensitive to whether the batch processor is under no-idling or full-batch policy.Singapore-MIT Alliance (SMA

Proceso de selección de estudiantes: una propuesta de transformación en la gestión administrativa-académica en la facultad de ingeniería de la universidad libre

El presente trabajo se basa en el diseño de una estrategia de gestión administrativa-académica aplicable al proceso de selección de estudiantes que aspiran ingresar a la facultad de Ingeniería de la Universidad Libre, la cual se fundamenta en los lineamientos propuestos por ABET en cuanto a habilidades y competencias propias de un ingeniero. De igual manera la estrategia es aplicable a los estudiantes de grado 11 en las instituciones de educación media con el fin de contribuir en el proceso de la orientación vocacional