Mitigation of differential movements at railroad bridge transition zones

Railroad transitions are track locations that experience a rapid change in track structure, such as a bridge or crossing. These locations are prone to differential movement and require frequent resurfacing to maintain an acceptable track geometry for both passing freight and high-speed passenger trains. In an effort to reduce the frequency of track resurfacing, an instrumentation and numerical modeling study was undertaken to (1) identify the root causes of the differential movement at transition zones, (2) develop and improve existing measurement techniques to evaluate track performance, and (3) recommend potential design, remedial, and resurfacing techniques to reduce and/or mitigate the differential movement. The two objectives of the field instrumentation program are: (a) develop a general overview of the loading environment and track movement and (b) develop a mobile system that focuses on tie behavior by measuring rail and crosstie displacements. Three-dimensional dynamic numerical modeling of bridge transition zones was also performed to investigate how changes in ballast settlement affect the transition zone loading environment. Based on field measurements and numerical modeling, three “root causes” were identified for differential movement at railway bridge transitions: (1) lack of track displacement on the bridge to balance transition zone track displacement, (2) increased applied loads in the transition zone, and (3) reduced-performance ballast conditions in the transition zone. To prevent the observed permanent vertical displacements, the following recommendations for future transition design are: (1) increase transient and permanent track displacements on the bridge to balance approach settlements, (2) use compacted and durable ballast and a working drainage system in the approach, (3) reduce ballast and subgrade settlement by increasing approach confinement in the approach, and (4) installing a resilient layer between the bottom of the concrete tie and top of the ballast to reduce ballast and tie degradation

Measurement and Characterization of Track Geometry Data: Literature Review and Recommendations for Processing FRA ATIP Program Data

Task Order 86From October 2018 to March 2019, the Federal Railroad Administration sponsored Transportation Technology Center, Inc. to conduct a literature review on the methods of measurement and characterization of track geometry. The goal of the review was to summarize the current state of track geometry measurement and to provide recommendations on methods for processing and characterizing track geometry data collected under FRA\u2019s Automated Track Inspection Program

Experimental investigations and analysis of piles as heat exchangers in pyroclastic soils

Sustainability and the greenhouse gases containment are the main purpose of the world policies to combat climate change. These are certainly in contrast with the world's growing demand for energy that is still too heavily based on fossil fuels, which are the main causes of gas emissions. The European Energy policies for more than 20 years have been based on the reduction of the carbon dioxide emissions using renewable energy sources and the reducing the final energy consumption. Shallow Geothermal Energy (SGE) is a rapidly growing technology all over Europe as a support for the Renewable Energy policies and European Directives because of its low greenhouse gas emissions into the atmosphere. It is considered a renewable source on the timescales of technological/societal systems because do not require the geological times of fossil fuel reserves such as coal, oil, and gas. Low enthalpy geothermal energy is used for heating and/or cooling building by exploiting the ground heat by ground heat exchangers connected to a geothermal source heat pump (GSHP). Energy piles represents a rather innovative technology that couples the role of the structural foundation with the role of the heat exchangers for GSHP plants to satisfy the building heating and cooling needs. Compared to the traditional pile foundations, these structures are loaded both by mechanical and thermal loads, where for thermal loads is commonly intended the application of a thermal distortion. During the last years, thermal and thermomechanical behavior of energy piles has been investigated by different approaches. In this PhD thesis the main aim was to investigate on the thermomechanical behavior of energy piles contextualized in Neapolitan context both by a geotechnical and energy point of view. First of all, a general overview about the social and energy European context and about the geothermal energy, an introduction to energy piles, by both a mechanical and an energetical point of view, was reported. The research was carried out following three different approaches: numerical modelling, small-scale tests, and field scale tests. As regard the numerical modelling, two types of analyses were carried out. In the former case by an axisymmetric FEM model, the impact of different surface thermal boundary conditions on the thermomechanical behavior of a single end bearing energy pile embedded in pyroclastic multilayer soil is investigated. The latter case is about the study of the interaction factors for a couple of energy piles where only one is thermally loaded while the other is embedded as a passive element in the deformation field generated by the loaded pile. The results were obtained for different pile spacings and for different subsoil and are presented in the chapter 4. Chapter 5 is dedicated to the small-scale test carried out on an aluminum energy prototype pile embedded in Neapolitan pyroclastic dry sand. Both thermal and thermomechanical tests were carried out considering a cyclical application of the thermal loads both in heating and in cooling mode and also considering the impact of different mechanical loads. The thermal loads provided to pile was obtained from a dynamic energy simulation of a building in the city of Naples. The results showed different axial forces distribution depending on the kind and magnitude of thermal and mechanical load applied on pile. Moreover, it was observed irreversible pile displacements during the application of cyclic thermal loads. Finally, in the chapter 6 a field test was carried out in the province of Naples on a bored concrete energy pile 12 m in length and 0,60 m in diameter embedded in pyroclastic soil and equipped with a spiral heat exchanger configuration. Three heating thermal tests with different time duration were carried out. From the tests was observed that the null point of the pile was located at the same depth for all the tests. Anyway, the magnitude of the axial forces depended on the duration of the test and the magnitude of the inlet heat carrier fluid. The pile heating did not affect the surrounding soil temperatures during the tests and a high flow rate of heat power exchanged between the pile and soil was measured. The measured pile displacements ranged between the 75% and 78% of the theoretical free displacement. Moreover, a long-time monitoring of the pile and surrounding soil was carried out for about 7 months. The data collected allowed to study the site underground temperatures trend over the time and for different depth. It was also possible to find the mean value of the subsoil thermal diffusivity and consequently predict a yearly temperature trend over the time and for different depth for the site

Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform

Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important. An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed. This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown

Cone Penetration Testing 2022

This volume contains the proceedings of the 5th International Symposium on Cone Penetration Testing (CPT’22), held in Bologna, Italy, 8-10 June 2022. More than 500 authors - academics, researchers, practitioners and manufacturers – contributed to the peer-reviewed papers included in this book, which includes three keynote lectures, four invited lectures and 169 technical papers. The contributions provide a full picture of the current knowledge and major trends in CPT research and development, with respect to innovations in instrumentation, latest advances in data interpretation, and emerging fields of CPT application. The paper topics encompass three well-established topic categories typically addressed in CPT events: - Equipment and Procedures - Data Interpretation - Applications. Emphasis is placed on the use of statistical approaches and innovative numerical strategies for CPT data interpretation, liquefaction studies, application of CPT to offshore engineering, comparative studies between CPT and other in-situ tests. Cone Penetration Testing 2022 contains a wealth of information that could be useful for researchers, practitioners and all those working in the broad and dynamic field of cone penetration testing

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

Molecular phylogeny of horseshoe crab using mitochondrial Cox1 gene as a benchmark sequence

An effort to assess the utility of 650 bp Cytochrome C oxidase subunit I (DNA barcode) gene in delineating the members horseshoe crabs (Family: xiphosura) with closely related sister taxa was made. A total of 33 sequences were extracted from National Center for Biotechnological Information (NCBI) which include horseshoe crabs, beetles, common crabs and scorpion sequences. Constructed phylogram showed beetles are closely related with horseshoe crabs than common crabs. Scorpion spp were distantly related to xiphosurans. Phylogram and observed genetic distance (GD) date were also revealed that Limulus polyphemus was closely related with Tachypleus tridentatus than with T.gigas. Carcinoscorpius rotundicauda was distantly related with L.polyphemus. The observed mean Genetic Distance (GD) value was higher in 3rd codon position in all the selected group of organisms. Among the horseshoe crabs high GC content was observed in L.polyphemus (38.32%) and lowest was observed in T.tridentatus (32.35%). We conclude that COI sequencing (barcoding) could be used in identifying and delineating evolutionary relatedness with closely related specie

Crab and cockle shells as heterogeneous catalysts in the production of biodiesel

In the present study, the waste crab and cockle shells were utilized as source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shells are calcium carbonate which transformed into calcium oxide upon activated above 700 °C for 2 h. Parametric studies have been investigated and optimal conditions were found to be catalyst amount, 5 wt.% and methanol/oil mass ratio, 0.5:1. The waste catalysts perform equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to five times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity