Scheduling of track inspection and maintenance activities in railroad networks

The U.S. railroad companies spend billions of dollars every year on railroad track maintenance in order to ensure safety and operational efficiency of their railroad networks. Besides maintenance costs, other costs such as train accident costs, train and shipment delay costs and rolling stock maintenance costs are also closely related to track maintenance activities. Optimizing the track maintenance process on the extensive railroad networks is a very complex problem with major cost implications. Currently, the decision making process for track maintenance planning is largely manual and primarily relies on the knowledge and judgment of experts. There is considerable potential to improve the process by using operations research techniques to develop solutions to the optimization problems on track maintenance. In this dissertation study, we propose a range of mathematical models and solution algorithms for three network-level scheduling problems on track maintenance: track inspection scheduling problem (TISP), production team scheduling problem (PTSP) and job-to-project clustering problem (JTPCP). TISP involves a set of inspection teams which travel over the railroad network to identify track defects. It is a large-scale routing and scheduling problem where thousands of tasks are to be scheduled subject to many difficult side constraints such as periodicity constraints and discrete working time constraints. A vehicle routing problem formulation was proposed for TISP, and a customized heuristic algorithm was developed to solve the model. The algorithm iteratively applies a constructive heuristic and a local search algorithm in an incremental scheduling horizon framework. The proposed model and algorithm have been adopted by a Class I railroad in its decision making process. Real-world case studies show the proposed approach outperforms the manual approach in short-term scheduling and can be used to conduct long-term what-if analyses to yield managerial insights. PTSP schedules capital track maintenance projects, which are the largest track maintenance activities and account for the majority of railroad capital spending. A time-space network model was proposed to formulate PTSP. More than ten types of side constraints were considered in the model, including very complex constraints such as mutual exclusion constraints and consecution constraints. A multiple neighborhood search algorithm, including a decomposition and restriction search and a block-interchange search, was developed to solve the model. Various performance enhancement techniques, such as data reduction, augmented cost function and subproblem prioritization, were developed to improve the algorithm. The proposed approach has been adopted by a Class I railroad for two years. Our numerical results show the model solutions are able to satisfy all hard constraints and most soft constraints. Compared with the existing manual procedure, the proposed approach is able to bring significant cost savings and operational efficiency improvement. JTPCP is an intermediate problem between TISP and PTSP. It focuses on clustering thousands of capital track maintenance jobs (based on the defects identified in track inspection) into projects so that the projects can be scheduled in PTSP. A vehicle routing problem based model and a multiple-step heuristic algorithm were developed to solve this problem. Various side constraints such as mutual exclusion constraints and rounding constraints were considered. The proposed approach has been applied in practice and has shown good performance in both solution quality and efficiency.

Simulação em uso dos pisos de madeira de Eucalyptus sp e Corymbia maculata

A caracterização anatômica, física, mecânica e química da madeira fornece informações importantes para sua melhor utilização. Contudo, para que madeiras se tornem boa opção para o mercado de pisos, adicionalmente é necessária a realização de ensaios que simulem suas reais condições em serviço. Esses ensaios simulam o pisoteio executado pelos sapatos de salto com pequenas áreas de pressão, o arraste e a queda de objetos, a resistência à abrasão da superfície e o atrito oferecido durante o deslocamento de pessoas que caminham sobre ele. Grande dificuldade da seleção de novas madeiras para pisos está na ausência de valores de referência físico-mecânicos. O presente trabalho visou a caracterizar as madeiras de Eucalyptus clöeziana F. Muell, de Eucalyptus microcorys F. Muell e de Corymbia maculata Hook, para as propriedades de densidade básica, retratibilidade, aplicação de carga rolante, de atrito estático e dinâmico, endentação causada por cargas aplicadas em pequenas áreas, impacto da esfera de aço cadente e resistência à abrasão. Foi observado que as madeiras estudadas podem ser utilizadas para a confecção de pisos, de acordo com seus resultados obtidos e por meio de comparações com resultados de literatura.

Multi-level, Multi-stage and Stochastic Optimization Models for Energy Conservation in Buildings for Federal, State and Local Agencies

Energy Conservation Measure (ECM) project selection is made difficult given real-world constraints, limited resources to implement savings retrofits, various suppliers in the market and project financing alternatives. Many of these energy efficient retrofit projects should be viewed as a series of investments with annual returns for these traditionally risk-averse agencies. Given a list of ECMs available, federal, state and local agencies must determine how to implement projects at lowest costs. The most common methods of implementation planning are suboptimal relative to cost. Federal, state and local agencies can obtain greater returns on their energy conservation investment over traditional methods, regardless of the implementing organization. This dissertation outlines several approaches to improve the traditional energy conservations models. Any public buildings in regions with similar energy conservation goals in the United States or internationally can also benefit greatly from this research. Additionally, many private owners of buildings are under mandates to conserve energy e.g., Local Law 85 of the New York City Energy Conservation Code requires any building, public or private, to meet the most current energy code for any alteration or renovation. Thus, both public and private stakeholders can benefit from this research. The research in this dissertation advances and presents models that decision-makers can use to optimize the selection of ECM projects with respect to the total cost of implementation. A practical application of a two-level mathematical program with equilibrium constraints (MPEC) improves the current best practice for agencies concerned with making the most cost-effective selection leveraging energy services companies or utilities. The two-level model maximizes savings to the agency and profit to the energy services companies (Chapter 2). An additional model presented leverages a single congressional appropriation to implement ECM projects (Chapter 3). Returns from implemented ECM projects are used to fund additional ECM projects. In these cases, fluctuations in energy costs and uncertainty in the estimated savings severely influence ECM project selection and the amount of the appropriation requested. A risk aversion method proposed imposes a minimum on the number of “of projects completed in each stage. A comparative method using Conditional Value at Risk is analyzed. Time consistency was addressed in this chapter. This work demonstrates how a risk-based, stochastic, multi-stage model with binary decision variables at each stage provides a much more accurate estimate for planning than the agency’s traditional approach and deterministic models. Finally, in Chapter 4, a rolling-horizon model allows for subadditivity and superadditivity of the energy savings to simulate interactive effects between ECM projects. The approach makes use of inequalities (McCormick, 1976) to re-express constraints that involve the product of binary variables with an exact linearization (related to the convex hull of those constraints). This model additionally shows the benefits of learning between stages while remaining consistent with the single congressional appropriations framework.

Housing wealth, financial wealth, and consumption: new evidence for Italy and the UK

This paper aims to investigate the long-run impact of housing and financial wealth on consumption in Italy and the UK using two different estimation methods. The novelty of the paper is to consider the recent financial crisis when studying wealth effects. The dynamics of wealth effects is also evaluated by a rolling regression analysis. The results show that: i) housing wealth plays no role in Italy, whereas it is significant in the UK; ii) in both countries, the financial wealth exerts a positive and significant impact on aggregate consumption; iii) by and large, the housing wealth effect assumes relatively increasing importance over time in the UK, while for Italy this is true for the financial wealth effect

Complete genome sequence of Deltapapillomavirus 4 (bovine papillomavirus 2) from a bovine papillomavirus lesion in Amazon Region, Brazil

The complete genome sequence of bovine papillomavirus 2 (BPV2) from Brazilian Amazon Region was determined using multiple-primed rolling circle amplification followed by Illumina sequencing. The genome is 7,947 bp long, with 45.9% GC content. It encodes seven early (E1, E2, E4, E5, E6, E7, and E8) and two late (L1 and L2) genes. The complete genome of a BPV2 can help in future studies since this BPV type is highly reported worldwide although the lack of complete genome sequences available.

Robust infraestructure design in rapid transit rail systems

Incidents and rolling stock breakdowns are commonplace in rapid transit rail systems and may disrupt the system performance imposing deviations from planned operations. A network design model is proposed for reducing the effect of disruptions less likely to occur. Failure probabilities are considered functions of the amount of services and the rolling stock’s routing on the designed network so that they cannot be calculated a priori but result from the design process itself. A two recourse stochastic programming model is formulated where the failure probabilities are an implicit function of the number of services and routing of the transit lines.

Train scheduling in high speed railways: considering competitive effects

The railway planning problem is usually studied from two different points of view: macroscopic and microscopic. We propose a macroscopic approach for the high-speed rail scheduling problem where competitive effects are introduced. We study train frequency planning, timetable planning and rolling stock assignment problems and model the problem as a multi-commodity network flow problem considering competitive transport markets. The aim of the presented model is to maximize the total operator profit. We solve the optimization model using realistic probleminstances obtained from the network of the Spanish railwa operator RENFE, including other transport modes in Spain

Queering archives: intimate tracings

In the longer introduction of Radical History Review’s two thematic issues “Queering Archives,” we frame the archive as an evasive and dynamic space animated by the tensions of knowledge production, absence, and presence. As Jeffrey Weeks argued in RHR in 1979, “The evolution of sexual meanings and identities that we have traced over the past hundred years or so are by no means complete.”1 Fragments of information float unfixed — historically unraveled — and we form archives when we pull the fragments into the orbit of efforts to know. Yet the business of knowing is unsteady, as scholars of sexuality and gender have amply demonstrated. Between the fraught and necessary practices of historicization, anachronism, interpretation, bias, and partial readings that propel historical scholarship, archival fragments fall in and out of the frame of an easily perceptible knowledge. Queer historical knowledge thus is evasive — like a coin dropped in the ocean and for which one grasps, reaching it only for it to slip away again, rolling deeper into the beyond. To say that the knowledge work of animating queer historical fragments is marked by such slipperiness is to underline how the archive negotiates the decomposition and recomposition of knowledge’s materials. We pull and push at the fading paper, the fraying fabric, the photographs bleaching into their backgrounds, and manipulate technologies on their way to obsolescence, all as part of some suturing effort of one kind or another.

Flexible roll forming of an automotive component with variable depth

Roll forming is a cost and energy efficient process for the manufacture of Ultra High Strength Steel (UHSS) structural and crash components in the automotive industry. The conventional roll forming process is limited to component having constant cross-section, while the recently deveoped Flexible Roll Forming (FRF) process allows the production of components in which the section varies over the length of the aprt; this permits optimization in terms of strength and weight. There has been an uptake in FRF in the heavy vehicle industry for the production of long and high strength structural parts, but passenger car bodies are more complex and generally parts require variations in width and also in depth. The widespread application of FRF in the automotive industy therefore requires the forming of components that have intricate variations in profile depth over the length of the part.
This work is a first comprehensive study of the FRF of high strength structural components with variable depth. For this, the FRF of an automotive bumper section is analyzed numerically using the commercial software package COPRA® FEA RF. A detailed analysis of the distribution and history of plastic strain in longitudinal, transcerse and thickness directions is performed and related to the shape defects observed in the proecss. The analysis shows that when forming variable depth components, zones of compressive longitudinal strain exist that lead to wrinkling defects. These can be reduced by applying additional flange contact during the operation. In general the current work suggests that the FRF of high strength components with variable depth is possible and can compete with other forming methods currently used in the automotive industry.

The effect of thermomechanical treatment on the microstructure and the mechanical behavior of a supersaturated Cu-Ag alloy

Supersaturated Cu-3at.% Ag alloy was processed by cold rolling and short-time annealing in order to achieve a combination of high strength and good tensile ductility. After annealing of the rolled samples a heterogeneous solute atom distribution was developed due to the dissolution of nanosized Ag particles in some volumes of the matrix. In regions with higher solute content, the high dislocation density formed due to rolling was stabilized, while in other volumes the dislocation density decreased. The heterogeneous microstructure obtained after annealing exhibited a much higher ductility and only a slightly lower strength than in the as-rolled state.

Advances in wrought magnesium alloys: Fundamentals of processing, properties and applications

This important book summarises the wealth of recent research on our understanding of process-property relationships in wrought magnesium alloys and the way this understanding can be used to develop a new generation of alloys for high-performance applications. After an introductory overview of current developments in wrought magnesium alloys, part one reviews fundamental aspects of deformation behaviour. These chapters are the building blocks for the optimisation of processing steps covered in part two, which discusses casting, extrusion, rolling and forging technologies. The concluding chapters cover applications of wrought magnesium alloys in automotive and biomedical engineering. With its distinguished editors, and drawing on the work of leading experts in the field, Advances in wrought magnesium alloys is a standard reference for those researching, manufacturing and using these alloys.

Dynamic strain-induced ferrite transformation (DSIT) in steels

The goal in the heat treatment or thermomechanical processing of steel is to improve the mechanical properties. For structural steel applications the general aim is to refine the ferrite grain size as this is the only method that improves both the strength and toughness simultaneously. For conventional hot rolling and accelerated cooling processes, it is difficult to refine the grain size below 5. μm without extensive alloying. However, it has been found that inducing transformation during deformation (i.e. dynamic transformation) can lead to grain sizes of the order of 1. μm, even in very simple steel compositions. The exact mechanism(s) for this transformation process are still being debated, and this has also been complicated by recent studies where such grain sizes can be obtained by static transformation from austenite that has been heavily deformed at low temperatures prior to the transformation. This chapter reviews the various major studies related in particular to dynamic transformation and considers the contributions from the deformed austenite structure developed prior to the transformation and the potential for dynamic recrystallisation of the ferrite. A key factor is proposed to be the early three-dimensional impingement of the ferrite which also provides an insight into cases where ultrafine grains are achieved statically.

Efficient detection of emergency event from moving object data streams

The advance of positioning technology enables us to online collect moving object data streams for many applications. One of the most significant applications is to detect emergency event through observed abnormal behavior of objects for disaster prediction. However, the continuously generated moving object data streams are often accumulated to a massive dataset in a few seconds and thus challenge existing data analysis techniques. In this paper, we model a process of emergency event forming as a process of rolling a snowball, that is, we compare a size-rapidly-changed (e.g., increased or decreased) group of moving objects to a snowball. Thus, the problem of emergency event detection can be resolved by snowball discovery. Then, we provide two algorithms to find snowballs: a clustering-and-scanning algorithm with the time complexity of O(n 2) and an efficient adjacency-list-based algorithm with the time complexity of O(nlogn). The second method adopts adjacency lists to optimize efficiency. Experiments on both real-world dataset and large synthetic datasets demonstrate the effectiveness, precision and efficiency of our algorithms © 2014 Springer International Publishing Switzerland.

An inverse routine to predict residual stress in sheet material

A method is presented to determine residual stress distribution in sheet material from data collected in a free bending test. It may be used where the residual stress distribution is symmetrical about the mid-surface as it is usually the case for frequently-used sheet metal post-processing techniques such as skin-pass or temper rolling, tension- and roller leveling. An existing inverse technique is used to obtain a residual stress profile and material constants that provide the best fit in a finite element analysis of bending with the experimentally derived moment-curvature relation. The method is verified for bending of a low-carbon stainless steel using measurement of residual stress by X-ray diffraction. The residual stresses were induced in the sheet by cold rolling. The technique described here can be used industrially as a rapid method of investigating residual stresses in incoming sheet. In processes where the deformation is principally one of bending, such as cold roll forming, it is known that residual stresses have an influence on shape defects and springback and the method presented here can be used to determine whether incoming sheet is suitable for further processing and also as a means of obtaining improved material data input for numerical simulation.

Equal-channel angular pressing and annealing of a twinning-induced plasticity steel : microstructure, texture, and mechanical properties

In this work, a high-manganese Fe-23Mn-1.5Al-0.3C Twinning-Induced Plasticity (TWIP) steel was subjected to plastic shear deformation using Equal-Channel Angular Pressing (ECAP) at 300 °C following route BC and additional annealing. The microstructure evolution during both deformation by ECAP and subsequent annealing was investigated and correlated with the mechanical properties. The successive grain refinement during ECAP was promoted by two parallel mechanisms, namely dislocation driven grain fragmentation and twin fragmentation, and accounted for the ultra-high strength. In addition, due to the relatively low volume fraction of deformation twins after ECAP at 300 °C, further contribution of deformation twinning during room temperature deformation allowed additional work-hardening capacity and elongation. During subsequent recovery annealing the ultra-fine grains and deformation twins were thermally stable, which supported retainment of the high yield strength along with regained uniform elongation. For the first time, the texture evolution during ECAP and during the following heat treatment was analyzed. After 1, 2, and 4 ECAP passes a transition texture with the characteristic texture components of both high- and low-SFE materials developed. During the following heat treatment the texture evolution proceeded similar to that observed in the same material after cold rolling. Retaining of the ECAP texture components due to oriented nucleation at grain boundaries and triple junctions as well as annealing twinning accounted for the formation of a weak, retained ECAP texture after recrystallization.