Derailment-based fault tree analysis on risk management of railway turnout systems

Railway turnouts are fundamental mechanical infrastructures, which allow a rolling stock to divert one direction to another. As those are of a large number of engineering subsystems, e.g. track, signalling, earthworks, these particular sub-systems are expected to induce high potential through various kind of failure mechanisms. This could be a cause of any catastrophic event. A derailment, one of undesirable events in railway operation, often results, albeit rare occurs, in damaging to rolling stock, railway infrastructure and disrupt service, and has the potential to cause casualties and even loss of lives. As a result, it is quite significant that a well-designed risk analysis is performed to create awareness of hazards and to identify what parts of the systems may be at risk. This study will focus on all types of environment based failures as a result of numerous contributing factors noted officially as accident reports. This risk analysis is designed to help industry to minimise the occurrence of accidents at railway turnouts. The methodology of the study relies on accurate assessment of derailment likelihood, and is based on statistical multiple factors-integrated accident rate analysis. The study is prepared in the way of establishing product risks and faults, and showing the impact of potential process by Boolean algebra

The effect of stabilized wastewater sludge on nitrogen and urease activity in a soil

Bu çalışmada, farklı yöntemlerle stabilize edilen çamurların uygulandığı topraklarda çeşitli azot formları ve üreaz aktivitesi değerlerinde meydana gelen değişimler belirlenmiştir. Evsel nitelikli ham arıtma çamuruna, patojen popülasyonunu değişen derecelerde azaltan dört farklı stabilizasyon yöntemi (havada kurutma, pastörizasyon, kireç stabilizasyonu ve kireç+kül stabilizasyonu) uygulanmıştır. Stabilize edilen arıtma çamurları 50 ve 100 ton ham kuru çamur ha-1 oranını sağlayacak şekilde 2 tekrarlamalı tesadüfi blok tasarımı düzeninde 500 g kuru toprak içeren kaplara eklenmiştir. Örnekler 28ºC’de 34 gün boyunca inkübe edilmiştir ve inkübasyonun 5, 8, 15, 22, 29 ve 34. günlerinde alınan örneklerde toplam azot, amonyum azotu ve nitrat azotu konsantrasyonları ile üreaz aktivitesi seviyeleri belirlenmiştir. Uygulanan havada kurutma, pastörizasyon, kireç stabilizasyonu ve kireç+kül stabilizasyonu yöntemleri, çamurun fekal koliform içeriğini önemli derecede (4.12 ila 7.74 log) azaltmıştır. Uygulanan stabilizasyon yöntemleri USEPA kriterleri çerçevesinde değerlendirildiğinde, kurutma, kireç stabilizasyonu ve kireç+kül stabilizasyonu yöntemlerinin B sınıfı biyokatı oluşturduğu sonucuna varılmıştır. Diğer yandan, çamurun pastörize edilmesi (70ºC’de 30 dk.) ile USEPA A sınıfı biyokatı kriterleri sağlanmıştır. Sonuçlar çamura uygulanan stabilizasyon yöntemlerinin arasındaki farkların, toprakların toplam azot konsantrasyonu ve üreaz aktivitesi değerine olan etkisinin önemsiz olduğunu göstermiştir. Diğer taraftan, çamur uygulanan topraklarda belirlenen amonyum ve nitrat azotu değerlerinin ise çamura uygulanan stabilizasyon yöntemlerine bağlı olarak değiştiği tespit edilmiştir. İnkübasyon sonuçları özellikle alkali çamur uygulanan topraklarda, nitrifikasyon prosesinin amonifikasyona göre daha hızlı yürüdüğünü göstermiştir. Anahtar Kelimeler: Arıtma çamuru, azot formları, çamur stabilizasyonu, üreaz aktivitesi, toprak.Wastewater sludge has been already utilized in agricultural applications for several years as it represents an alternative source of nutrients for plant growth and an efficient soil conditioner enhancing certain physical properties of soil. However, wastewater sludge may contain pathogenic organisms and pollutants. This may negatively affect the soil properties. Recently increased attention was paid to the sludge stabilization process aiming to reduce the microbial content of sludge (pathogens). In this context several methods, such as biological digestion, composting, lime stabilisation, heat treatment have been used to eliminate pathogens from sludge. In this research, variations of various nitrogen forms and urease activity values have been determined in soils amended with wastewater sludges treated with different stabilization methods. Raw domestic sludge samples were treated with four different stabilization processes (air drying, pasteurization, lime stabilization and lime+fly ash stabilization) for reducing pathogen population with varying efficiency. Details of the processes are given below: air drying process: sludge was dried at 35°C by using a supplemental heat source; pasteurization: sludge was heated at 70°C for 30 minutes; lime stabilization: sludge was mixed with 15% of lime(CaO) on dry-weight basis; lime+fly ash stabilization: lime (10%)-fly ash (40%) mixture was added to sludge to increase the pH to 12. Lime is considered as one of the most common amendment materials for sewage sludge stabilization, as it plays significant role in reducing the microbial content of sludge (pathogens), enhancing the agricultural benefits and lowering the respective environmental risks. Fly ash, i.e. the by-product produced from fossil fuel thermal power plants, may contain increased amounts of calcium and magnesium oxides, depending upon the coal sources and may present highly alkaline values similar to lime. Thus, fly ash can be used as an alternative material for sludge stabilization with additional benefits, such as the reduced purchasing cost, and the minimization of fly ash disposal cost. Furthermore, the combined addition of fly ash and lime in small dosages to sewage sludge may result to an efficient removal of pathogens. In this research, de-watered sludge sample was collected from the treatment plant of canned food industry. The fly ash used in this study was obtained from Orhaneli Power Station where lignite is used for fuel. Technical grade anhydrous calcium oxide (quicklime 96%) was used together with fly ash in alkaline stabilisation. Stabilized sludge samples were amended to soil pots (500 g air dried soil) at rate equivalent to 50 and 100 tons dry sludge ha-1 and the pots were then arranged in a randomized block design with two replicates. The samples were incubated at 28°C for 34 days and total-N, ammonium-N and nitrate-N concentrations and urease activity levels were determined at 5, 8, 15, 22, 29 and 34 days of incubation period. Fecal coliform numbers were determined by Most Probable Number Method of Standard Methods. Concentrations of nitrate-N and ammonium-N were determined in samples which were extracted using 2 M KCI. The concentrations in extracts were analyzed by steam distillation with MgO and devarda alloy. Total N contents were measured by Kjeldahl digestion method. The urease activity of the soil was determined as described by Tabatabai. Applied methods of air drying, pasteurization, lime stabilization and lime+fly ash stabilization significantly decreased (4.12 to 7.74 log) the fecal coliform contents of wastewater sludge. When applied stabilization methods were evaluated by USEPA criteria, it can be concluded that air drying, lime stabilization and lime+fly ash stabilization generated Class B biosolid products. On the other hand, Class A biosolid requirements were achieved by pasteurization of sludge(70°C for 30 min.). The results indicated that the effects of applied sludge stabilization methods on total N concentration and urease activity values of soils were found to be insignificant. However, the ammonium and nitrate nitrogen concentrations in sludge amended soils were dependent on the applied sludge stabilization methods. In general, low levels of ammonium and high levels of nitrate nitrogen were determined in sludge amended soils during the incubation period. The results of the incubation indicated that nitrification proceeded much faster than ammonification especially in soils amended with alkaline sludges. Keywords: Nitrogen forms, sludge stabilization, soil, urease activity, wastewater sludge

Computers in Secondary Schools: Educational Games

This entry introduces educational games in secondary schools. Educational games include three main types of educational activities with a playful learning intention supported by digital technologies: educational serious games, educational gamification, and learning through game creation. Educational serious games are digital games that support learning objectives. Gamification is defined as the use of "game design elements and game thinking in a non-gaming context" (Deterding et al. 2011, p. 13). Educational gamification is not developed through a digital game but includes game elements for supporting the learning objectives. Learning through game creation is focused on the process of designing and creating a prototype of a game to support a learning process related to the game creation process or the knowledge mobilized through the game creation process. Four modalities of educational games in secondary education are introduced in this entry to describe educational games in secondary education: educational purpose of entertainment games, serious games, gamification, and game design

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN