Shakedown for slab track substructures with stiffness variation

In this paper, shakedown analyses are carried out to predict the long-term response of slab track substructures under repeated moving train loads. The train loads are converted into a distributed moving load on the substructure surface by using a simplified track analysis. Based on Melan’s static shakedown theorem, a well-established shakedown analysis method is extended to determine shakedown limits of the slab track substructures. The influence of a linearly increasing stiffness modulus on the shakedown limits is considered by conducting finite- element analysis with a user-defined material. It is found that a rise in stiffness modulus or stiffness variation ratio can either increase or decrease the shakedown limit, depending on the competitive effects of the two mechanisms. Furthermore, the subgrade thickness determines the dominant mechanism

A study on wear evaluation of railway wheels based on multibody dynamics and wear computation

The wear evolution of railway wheels is a very important issue in railway engineering. In the past, the reprofiling intervals of railway vehicle steel wheels have been scheduled according to designers' experience. Today, more reliable and accurate tools in predicting wheel wear evolution and wheelset lifetime can be used in order to achieve economical and safety benefits. In this work, a computational tool that is able to predict the evolution of the wheel profiles for a given railway system, as a function of the distance run, is presented. The strategy adopted consists of using a commercial multibody software to study the railway dynamic problem and a purpose-built code for managing its pre- and post-processing data in order to compute the wear. The tool is applied here to realistic operation scenarios in order to assess the effect of some service conditions on the wheel wear progression

Plausible Petri nets as self-adaptive expert systems: A tool for infrastructure asset monitoring

This article provides a computational framework to model self-adaptive expert systems using the Petri net (PN) formalism. Self-adaptive expert systems are understood here as expert systems with the ability to autonomously learn from external inputs, like monitoring data. To this end, the Bayesian learning principles are investigated and also combined with the Plausible PNs (PPNs) methodology. PPNs are a variant within the PN paradigm, which are efficient to jointly consider the dynamics of discrete events, like maintenance actions, together with multiple sources of uncertain information about a state variable. The manuscript shows the mathematical conditions and computational procedure where the Bayesian updating becomes a particular case of a more general basic operation within the PPN execution semantics, which enables the uncertain knowledge being updated from monitoring data. The approach is general, but here it is demonstrated in a novel computational model acting as expert system for railway track inspection management taken as a case study using published data from a laboratory simulation of train loading on ballast. The results reveal selfadaptability and uncertainty management as key enabling aspects to optimize inspection actions in railway track, only being adaptively and autonomously triggered based on the actual learnt state of track and other contextual issues, like resource availability, as opposed to scheduled periodic maintenance activities.Lloyd'sRegister Foundation, Grant/Award Number: RB4539; Engineering and Physical SciencesResearch Council, Grant/Award Number:EP/M023028/

Static and dynamic behaviours of railway prestressed concrete sleepers with longitudinal through hole

As the crosstie beam in railway track systems, the prestressed concrete sleepers (or railroad ties) are principally designed in order to carry wheel loads from the rails to the ground. Their design takes into account static and dynamic loading conditions. It is evident that prestressed concrete has played a significant role as to maintain the high endurance of the sleepers under low to moderate repeated impact loads. In spite of the most common use of the prestressed concrete sleepers in railway tracks, there have always been many demands from rail engineers to improve serviceability and functionality of concrete sleepers. For example, signalling, fibre optic, equipment cables are often damaged either by ballast corners or by tamping machine. There has been a need to re-design concrete sleeper to cater cables internally so that they would not experience detrimental or harsh environments. Accordingly, this study will investigate the effects of through hole or longitudinal hole on static and dynamic behaviours of concrete sleepers under rail shock loading. The modified compression field theory for ultimate strength design of concrete sleepers will be highlighted in this study. The outcome of this study will enable the new design and calculation methods for prestressed concrete sleepers with holes and web opening that practically benefits civil, track and structural engineers in railway industry

The Geochemistry of Rocks from Asama Volcano, Japan. New Approaches in the Quantitative Interpretation of the Chemical Composition of Volcanic Rocks

In dealing with the geochemistry of volcanic rocks, it appears imperative, first, to refine the procedure of rock analysis with respect to both major and minor components, and second, to improve present methods of interpreting analytical data on common rock suites such as basalts, andesites and dacites. In regard to the first problem, the rapid method of silicate analysis as described by Shapiro and Brannock (1956) and by Riley (1958) deserves special attention. With such a method it is possible to estimate the accuracy and precision of data with far greater ease than is possible with a classical one, yet without any loss of quality. For the determination of some components, however, it is felt that the procedures recommended previously lack precision and/or simplicity. In Part I of this paper, new methods are suggested for these components. The sum of Mg, Ca and Mn is titrated with EDTA in the presence of Al, Fe and other metals, using thymolphthalein complexone as indicator at pH 10-10.5. The sum of Al and Fe is determined by the back-titration of excess EDTA with the standard Cu solution. PAN is used as indicator at pH about 4, and tartrate is added as the masking agent of Ti. Na and K are determined by flame photometry using very dilute solutions (1-5ppm Na or K), without the separation of other metals and without the use of the internal standard. Sr is included in the scheme of analysis, and is determined by flame photometry according to the standard addition technique. These procedures are tested for their accuracy using the standard samples G-1 and W-1 (Tables 3, 5, 9, 12 and 15). Procedures for other components are also described in the text in full detail. The system of analytical procedures recommended is shown in Table 16. To investigate the problem of the interpretation of compositional variation, typical rocks from Asama volcano and the surrounding area were selected, namely, andesites and dacites of calc-alkaline type. Twenty-one samples, described in Tables 18 and 19, are analyzed according to the above procedures. Results are shown in Table 20. Variation diagrams are presented in Figs. 3 to 5. Since it may be questioned whether the "trend" seen in the diagrams implies a genetic relationship, a least squares approximation technique has been introduced in order to determine whether the composition of the main components of a rock (F) can be expressed by the linear combination of a selected set of compositions of a magma and the phenocrysts crystallized from it : F(o)=F(1)x(1)+F(2)x(2)+······+F(m)x(m) ······(1) where F(1), F(2), ... denote the compositions of a magma and minerals, and F(o) is the calculated composition of F. These calculations lead to the conclusion that there are at least two series of rocks in Asama (Tables 25 to 30 and Fig. 9), distinguished from each other mainly by their K(2)O content. Those rocks showing features of assimilation (Aramaki, 1963) all belong to the K(2)O-rich series. Contents of minor components such as TiO(2), MnO, P(2)O(5) and SrO are analyzed by the linear regression technique in two ways, for example : TiO(2)(o)=C(1)x(1)+C(2)x(2)+ ······(2) and TiO(2)(o)=aMgO+bFe(o) +cK(2)O ······(3) These methods are found useful in discriminating rocks of different ongm and in distinguishing the characteristic behavior of each component. Results of calculations (Tables 31 to 34) support the conclusion reached by calculations based on the contents of major components

Influence of amyloglucosidase in bread crust properties

Enzymes are used in baking as a useful tool for improving the processing behavior or properties of baked products. A number of enzymes have been proposed for improving specific volume, imparting softness, or extend the shelf life of breads, but scarce studies have been focused on bread crust. The aim of this study was to determine the use of amyloglucosidase for modulating the properties of the bread crust and increase its crispness. Increasing levels of enzyme were applied onto the surface of two different partially bake breads (thin and thick crust bread). Amyloglucosidase treatment affected significantly (P<0.05) the color of the crust and decreased the moisture content and water activity of the crusts. Mechanical properties were modified by amyloglucosidase, namely increasing levels of enzyme promoted a decrease in the force (Fm) required for crust rupture and an increase in the number of fracture events (Nwr) related to crispy products. Crust microstructure analysis confirmed that enzymatic treatment caused changes in the bread crust structure, leading to a disruption of the structure, by removing the starchy layer that covered the granules and increasing the number of voids, which agree with the texture fragility.Authors acknowledge the financial support of Spanish Ministry of Economy and Sustainability (Project AGL2011-23802), the European Regional Development Fund (FEDER), Generalitat Valenciana (Project Prometeo 2012/064) and the Consejo Superior de Investigaciones Cientificas (CSIC). R. Altamirano-Fortoul would like to thank her grant to CSIC. The authors also thank Forns Valencians S. A. (Spain) for supplying commercial frozen partially baked breads.Altamirano Fortoul, RDC.; Hernando Hernando, MI.; Molina Rosell, MC. (2014). Influence of amyloglucosidase in bread crust properties. 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Railway-induced ground vibrations – a review of vehicle effects

This paper is a review of the effect of vehicle characteristics on ground- and track borne-vibrations from railways. It combines traditional theory with modern thinking and uses a range of numerical analysis and experimental results to provide a broad analysis of the subject area. First, the effect of different train types on vibration propagation is investigated. Then, despite not being the focus of this work, numerical approaches to vibration propagation modelling within the track and soil are briefly touched upon. Next an in-depth discussion is presented related to the evolution of numerical models, with analysis of the suitability of various modelling approaches for analysing vehicle effects. The differences between quasi-static and dynamic characteristics are also discussed with insights into defects such as wheel/rail irregularities. Additionally, as an appendix, a modest database of train types are presented along with detailed information related to their physical attributes. It is hoped that this information may provide assistance to future researchers attempting to simulate railway vehicle vibrations. It is concluded that train type and the contact conditions at the wheel/rail interface can be influential in the generation of vibration. Therefore, where possible, when using numerical approach, the vehicle should be modelled in detail. Additionally, it was found that there are a wide variety of modelling approaches capable of simulating train types effects. If non-linear behaviour needs to be included in the model, then time domain simulations are preferable, however if the system can be assumed linear then frequency domain simulations are suitable due to their reduced computational demand