UN ALGORITMO DI CONTATTO RUOTA-ROTAIA PER L'IMPIEGO IN SISTEMI DI CALCOLO IN TEMPO REALE

Nello studio del comportamento dinamico dei veicoli ferroviari uno degli aspetti di maggiore rilevanza è il problema della determinazione delle forze scambiate al contatto ruota-rotaia. Questo problema è tuttora oggetto di studi che da un lato cercano di ottenere risultati di maggiore accuratezza e dall'altro cercano di ridurre i tempi di calcolo. Il lavoro illustra i risultati ottenuti con l'algoritmo di contatto sviluppato presso il Politecnico di Torino, denominato RTCONTACT; questo codice, che è un'evoluzione dell'algoritmo CONPOL, è il risultato di lunghe attività di ricerca, le versioni precedenti sono state utilizzate in cosimulazione con codici MBS e in ambiente Matlab® per simulare il comportamento di veicoli ferroviari. Il codice è stato sviluppato anche basandosi su risultati sperimentali ottenuti da banco prova "Roller-Rig". In questo lavoro si illustrano le principali caratteristiche del codice e si presentano confronti con altri codici numerici, pubblicazioni e normative per i risultati di maggiore interesse per il contatto ruota-rotai

Design and Simulation of a Railway Vehicle for the Transport of People with Reduced Mobility

One of the most important aspects of the design activity of passenger railway vehicles is the optimization of the comfort level that is often in contrast with other requirements, such as low weight, to reduce energy consumption, and high and flexible seating capacity. Due to the coach weight reduction, the car body structure becomes more susceptible to structural vibrations that affect the passenger comfort. In modern vehicles, seats are important elements to achieve the desired comfort, but in order to design and estimate the actual comfort level, the whole system must be considered, including the track excitations, a vehicle detailed dynamic model, and the coach and the seat flexibility. This paper describes a numerical model of a double-deck vehicle developed using a MB code that considers measured track irregularities, a detailed vehicle model, and a transfer function of the seat obtained by experimental tests on an optimized seat. In order to make the numerical model more realistic, the coach has been modeled as a flexible body to consider the effect of its natural frequencies. The work has been performed within the "CARITAS" project, whose aim is the design of a high comfort vehicle for people with reduced mobility

monitoring of railway freight vehicles using onboard systems

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study of wheel rail adhesion during braking maneuvers

Abstract The present work aims to better understand the phenomenon of adhesion under degraded conditions during railway braking maneuvers with the aim of optimizing the anti-slip algorithms in order to reduce damage to the profiles of wheels and rails and to minimize the braking distance. The proposed approach is based on the analysis of experimental data acquired during braking tests carried out on track, considering different types of vehicles and different types of contaminants, able to reproduce the typical degraded adhesion conditions occurring during normal operation. The work describes a numerical model that allows to evaluate the dynamics of the vehicle during the braking operation and to correlate the pressures to the brake cylinder, which are related to the braking forces, and the angular velocities measured on the axles of the vehicle, with the adhesion coefficient

Poços de água subterrânea construídos pela CPRM-Porto Alegre no RS, com ênfase à área gonduânica

O trabalho não apresenta resumo

Estudo comparativo, prospectivo e randomizado entre uroterapia e tratamento farmacológico em crianças com incontinência urinária

OBJECTIVE: To verify and compare the results of behavioral modification plus pelvic floor muscle training and behavioral modifications plus oxybutynin chloride in children with nonmonosymptomatic enuresis. METHODS: A total of 47 children were randomized using opaque and sealed envelopes sequentially numbered. Group I was composed of 21 children who underwent antimuscarinic treatment (oxybutynin), and Group II was composed of 26 patients who underwent pelvic floor muscle training. Both groups were instructed as to behavioral modifications. RESULTS: The voiding diary results were compared each month between Groups I and II. In the first month of treatment, children in Group I presented 12.2 dry nights, 13.4 in the second month, and 15.9 in the last month. In Group II, the results were: 14.9 dry nights in the first month, 20.8 dry nights in the second and 24.0 dry nights in the last month. There was a significant difference between the groups in second and third months. CONCLUSION: Pelvic floor exercises associated with behavioral changes were more effective than pharmacological treatment in children with urinary incontinence.OBJETIVO: Verificar e comparar os resultados da modificação comportamental associado ao treinamento dos músculos do assoalho pélvico e modificação comportamental associado ao uso de cloridrato de oxibutinina em crianças com enurese não monossintomática. MÉTODOS: Foram randomizadas 47 crianças por meio de envelopes opacos e selados com numeração sequencial. O Grupo I foi composto por 21 crianças que receberam tratamento com antimuscarínico (oxibutinina) e o Grupo II por 26 pacientes que receberam treinamento dos músculos do assoalho pélvico. Ambos os grupos foram instruídos em relação à modificação comportamental. RESULTADOS: Os resultados do diário miccional foram comparados cada mês entre os Grupos I e II. No primeiro mês de tratamento, as crianças do Grupo I apresentaram 12,2 noites secas, 13,4 no segundo mês e 15,9 no último mês. No Grupo II, os resultados foram: 14,9 noites secas no primeiro mês, 20,8 no segundo mês e 24,0 no último mês. Houve diferença significativa entre os grupos no segundo e no terceiro mês. CONCLUSÃO: Os exercícios do assoalho pélvico associados a mudança comportamental foram mais efetivos do que o tratamento farmacológico em crianças com incontinência urinária.20320

ESDA2006-95571 NUMERICAL SIMULATION OF WEAR IN RAILWAY WHEEL PROFILES

ABSTRACT The work describes a method to predict the evolution of the wheel profile of a railway vehicle, depending on the load history acting on the wheelset. The method is based on the determination of the wear on the contact area, which is divided into finite elements according to the strip theory. For each element, in presence of slip, the amount of material loss is evaluated depending on the local value of tangential force and creepage (the meaning of creepage is assumed according to the definition given in The wear is calculated for the entire contact area superimposing the contribution of each element. The motion of the wheelset in lateral direction causes a motion of the contact patch along the profile. Sequentially, the contact area will acquire a different contact shape and stress distribution. The shape of the worn profile depends on both the load condition and the motion of the wheelset with respect to the track. This profile can be obtained from the new one by subtracting at each time step the material removed from the contact area. This procedure is simple, but requires variable profiles for each time step, and is not efficient in computational terms. The strategy proposed here by the authors, is to consider finite periods obtained superimposing several revolution of the wheelset. The worn profile is evaluated in a single step from the cumulative of damage of an entire period. The limitation of this method consists in the different behavior of a wheelset with worn profile respect to a wheelset with new ones, and therefore produces different wear. It is necessary to determine an optimal value for the period to be used to re-evaluate the profile shape, in order to minimize the difference in the predicted shape itself. The method is applied to a suspended wheelset, running on a simulated test track, with S1002/UIC60 profiles. Different periods of re-evaluation of the profiles are considered in order to demonstrate the influence of this parameter. INTRODUCTION Wear determines the lifespan of a construction, and in railway applications it affects both rails and wheels, which are the two elements providing guidance and support to the motion of the vehicle. Reduction of wear is therefore one of the important objectives of railway technology; tribology studies are used to develop new design methodologies, in order to reduce wear and increase life of rails and wheels. Considering the wheel wear, it is important to evaluate not only the total amount of wear, but also the shape variation of the profile. The same amount of wear can cause a higher or lower deterioration of the wheelset performance depending on the new shape of the worn profile. In fact in case of high equivalent conicity, the stability of the vehicle can be heavily reduced. In general, it is possible to distinguish if the wear is distributed uniformly along the circumferential direction or not. In the last case, unroundness may arise; the wheel is no longer exactly a body of revolution but exhibits waves in the circumferential direction or flatness, this is a problematic type of wear as the rolling stock is severely and dynamically loaded. This type of wear is usually related to braking operations (wheel flat), or to problems depending on material and loading conditions. Prediction of this type of wear requires a complex numerical investigations involving real time simulations, low time step and precise determination of the loads acting on the wheel. In this work, the study is limited to wear with uniform distribution in the circumferential direction; in this case the wheel remains a body of revolution, but it changes shape in the transversal section

Fogli 609-596, Termini Imerese-Capo Plaia

Il Servizio Geologico Nazionale ha unificato i Fogli 609 "Termini Imerese" e 596 "Capo Plaia" in un unico Foglio denominato 609/596 "Termini Imerese-Capo Plaia" allo scopo di uniformare i rilievi e raccoglierne la descrizione in un unico volume delle Note Illustrative. Il Foglio 609/596 "Termini Imerese-Capo Plaia" della Carta Geologica d’Italia in scala 1:50.000 è stato realizzato nell’ambito del Progetto CARG con i fondi della Legge 67/88 - Legge 226/99 con una convenzione tra Servizio Geologico Nazionale ora ISPRA) e Regione Siciliana. Le aree ricadono interamente nella Provincia di Palermo, comprendono la fascia marina del Golfo di Termini Imerese fino al promontorio di Capo Plaia, la regione dei Monti di Termini Imerese e Trabia ad ovest e il settore occidentale del gruppo montuoso delle Madonie ad est. Tra questi rilievi si sviluppa un’ampio settore collinare inciso dai fiumi Torto e Imera settentrionale (o Fiume Grande)

Effects and outcome of a policy of intermittent imatinib treatment in elderly patients with chronic myeloid leukemia

Key Points INTERIM treatment affects cytogenetic and molecular response, but not the outcome. No patients treated with INTERIM progressed to accelerated or blast phase.</jats:p