1,720,952 research outputs found
Distributed Optimization for Railway Track Maintenance Operations Planning
No full textAn essential component of railway infrastructures is track ballast. As railway track is used frequently by passing rolling stocks, its performance degrades over time. At certain degradation levels, maintenance interventions must be carried out to improve the track performance so to meet technical and safety regulations. In this way, the risk of accident or derailment can be minimized and the railway interoperability is ensured. Furthermore, the responsibility of designing maintenance plan belongs to infrastructure managers. To help them, predictive strategies based on optimization can suggest the optimal schedule to maintain the track over a certain time period. In this way, track performance and maintenance costs can be explicitly optimized over the whole life cycle of the track.However, a railway network typically consists of multiple track sections, each of them with different degradation level and parameters. Hence, the optimization of track maintenance can be considered as a large-scale problem which has a large number of decision variables. For such kind of problem, the conventional centralized optimization is very difficult or even not tractable to solve due to limitations on the computational time and resources. One way to overcome this issue is by applying the so-called distributed optimization scheme. In such approach, the original optimization problem is partitioned into multiple smaller, tractable subproblems. Therefore, the optimization is tractable and more preferred for real-life implementations.This thesis develops distributed optimization approaches for track maintenance operations planning problem. Three different schemes are compared: Parallel Augmented Lagrangian Relaxation (PALR), Alternating Direction Method of Multipliers (ADMM), and Distributed Robust Safe But Knowledgeable (DRSBK). As these distributed approaches basically designed for convex problems, extension techniques to handle non-convex nature of the proposed optimization problem are implemented. Furthermore, some case studies are defined to evaluate the algorithms from both performance and numerical perspectives. In simulations of small, medium, and large-scale instances, it is shown that in most cases, DRSBK can outperform the other distributed approaches, by providing the closest-to-optimum solution to the centralized optimization problem while having the shortest computation time.Mechanical Engineering | Systems and Contro
Distributed optimization for railway track maintenance operations planning
No full textIn this paper, distributed optimization approaches are developed for the planning of maintenance operations of large-scale railway infrastructure formulated as a Mixed-Integer Linear Programming (MILP) problem. The proposed planning problem is solved using three different distributed optimization schemes: Parallel Augmented Lagrangian Relaxation (PALR), Alternating Direction Method of Multipliers (ADMM), and Distributed Robust Safe But Knowledgeable (DRSBK). The original distributed algorithms are modified to handle the non-convex nature of the optimization problem and to improve the solution quality. The results of large-scale test instances show that DRSBK can outperform the other distributed approaches, by providing the closest-to-optimum solution while requiring the lowest computation time.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Railway EngineeringTeam Bart De Schutte
Arabic printing in Malta 1825-1845 : Its history and its place in the development of print culture in the Arab Middle East.
Full text linkSIGLEAvailable from British Library Document Supply Centre- DSC:D174840 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The detection of porosity on designed references samples with various porosity levels produced by 3D printing to investigate the accuracy of computed tomography (CT) scans (XTH225ST)
No full textNon-destructive testing (NDT) is a technique used to analyse the internal and external features of a part without causing any damage to it. There are wide varieties of NDT methods being practiced in the different engineering fields and for this project, we will be investigating mainly on Computed Tomography (CT) scanning and the experiment of Archimedes’ Principle. In contrast to other NDT scanning methods, CT scan is capable of scanning and reconstructing the scanned image into a full 3D image with all the internal and external features of the part. Hence, it helps to reveal any defects or porosities that maybe present in it. For this project, the author will be investigating on the accuracy of a CT scan machine; Nikon XTH225ST. A comparison will be made based on the results obtained between Archimedes’ Principle and CT scan and the author is interested to find out what is the deviation of the CT Scanning machine capabilities as compared to the theoretical results. Therefore, for this project, 3D printed specimens with different percentages and sizes of designed porosities will be used for analysis. Each specimen with different porosities will be analysed and a comparison between theoretical data from the CAD model and the results obtained through CT scanning will be made.Bachelor of Engineering (Mechanical Engineering
TibbOnto: Knowledge Representation of Prophet Medicine (Tibb Al-Nabawi)
No full textAbstractThe Quran and Hadith are the two fundamental sources of Islamic legislation. Hadith are narrations passed from Prophet companions regarding the words and deeds of Prophet Muhammad (peace be upon him). Hadith books contain topics related to all aspects of Muslim life. In this paper, we build a domain-specific ontology (Tibb Al-Nabawi ontology) to present the Prophet's medicine in a semantic ontological representation. Our source of knowledge is based on an authentic Tibb Al-Nabawi Hadith. We have identified the main classes and the relationship among them. The proposed ontology can be extended in the future to automatically generate treatments for specific diseases according to the Prophet's actions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Coldplay Concert Rejection in Indonesia An Analysis of Islamic Identity Mobilization
Full text linkIslam is not only a religion but also an identity for its believers. The fact that Islam is an identity made it subject to ongoing reinterpretation and reconstruction based on the context by certain actors. Therefore, through this article, the author aims to examine the mobilization of Islamic identity within the context of the Coldplay concert rejection by The 212 Alumni Brotherhood (PA) and other Islamist groups with aligned ideologies. This qualitative study, based on library research from journals, books, and media reports, applies historical and political approaches to analyze Islamic identity mobilization in Indonesia, focusing on data surrounding the Coldplay concert rejection within recent political contexts. The author finds that the rejection phenomenon is the result of the contestation of Islamic identity that has been contested in Indonesia and the strengthening of political Islam identity. Indications of strengthening this identity can be seen from the rise of identity politics in the general elections in recent years. And finally, the author concludes that the rejection of the Coldplay concert is an effort to mobilize Islamic identity as the majority in Indonesia, which in turn has contributed to causing discriminatory actions against minority communities.AbstrakIslam bukan hanya agama, tetapi juga identitas bagi para pemeluknya. Fakta bahwa Islam adalah identitas menjadikannya terus mengalami reinterpretasi dan rekonstruksi berdasarkan konteks tertentu oleh para aktor tertentu. Oleh karena itu, melalui artikel ini, penulis bertujuan untuk mengkaji mobilisasi identitas Islam dalam konteks penolakan konser Coldplay oleh Persaudaraan Alumni 212 (PA) dan kelompok Islamis lain yang memiliki ideologi sejalan. Penelitian kualitatif ini, berdasarkan studi pustaka dari jurnal, buku, dan laporan media, menerapkan pendekatan historis dan politis untuk menganalisis mobilisasi identitas Islam di Indonesia, dengan fokus pada data terkait penolakan konser Coldplay dalam konteks politik terkini. Penulis menemukan bahwa fenomena penolakan ini merupakan hasil kontestasi identitas Islam yang terus diperebutkan di Indonesia serta penguatan identitas politik Islam. Indikasi penguatan identitas ini terlihat dari meningkatnya politik identitas dalam pemilu beberapa tahun terakhir. Akhirnya, penulis menyimpulkan bahwa penolakan konser Coldplay adalah upaya mobilisasi identitas Islam sebagai mayoritas di Indonesia, yang pada gilirannya turut berkontribusi terhadap tindakan diskriminatif terhadap kelompok minoritas
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