824,888 research outputs found

    The ATLAS SCT grounding and shielding concept and implementation

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    This paper presents a complete description of Virgo, the French-Italian gravitational wave detector. The detector, built at Cascina, near Pisa (Italy), is a very large Michelson interferometer, with 3 km-long arms. In this paper, following a presentation of the physics requirements, leading to the specifications for the construction of the detector, a detailed description of all its different elements is given. These include civil engineering infrastructures, a huge ultra-high vacuum (UHV) chamber (about 6000 cubic metres), all of the optical components, including high quality mirrors and their seismic isolating suspensions, all of the electronics required to control the interferometer and for signal detection. The expected performances of these different elements are given, leading to an overall sensitivity curve as a function of the incoming gravitational wave frequency. This description represents the detector as built and used in the first data-taking runs. Improvements in different parts have been and continue to be performed, leading to better sensitivities. These will be detailed in a forthcoming paper

    Family residence

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    BakaláƙskĂĄ prĂĄce je zaměƙena na konstrukčnĂ­ ƙeĆĄenĂ­ rodinnĂ©ho domu ve formě provĂĄděcĂ­ dokumentace. RodinnĂœ dĆŻm je navrĆŸen pro jednu rodinu. Objekt je situovĂĄn na mĂ­rně svaĆŸitĂ© a velmi prostornĂ© parcele č. 693/12, k.Ăș. Lhota za ČervenĂœm Kostelcem, ČervenĂœ Kostelec, KrĂĄloveradeckĂœ kraj. DĆŻm je navrĆŸen jako dvouposchoďovĂœ s garĂĄĆŸĂ­ pro dvě auta. Objekt je zděnĂœ z pĂłrobetonovĂœch blokĆŻ. Nad obytnou částĂ­ je navrĆŸena sedlovĂĄ stƙecha se sklonem 38° a nad prostorem garĂĄĆŸe je navrĆŸena plochĂĄ pochozĂ­ stƙecha se sklonem 1°.The bachelor’s thesis is aimed on the solution of construction of "Family residence" in form of project documentation. The house is intended for one family. It is located on a slightly sloping parcel 693/12, cadastral area Lhota za ČervenĂœm Kostelecem, ČervenĂœ Kostelec, KrĂĄlovehradeckĂœ district. The house is without basement and has two storeys with garage for two cars. The object is masonry building with gable roof with a slope of 38° and a flat roof with a slope of 1 °.

    Air Traffic Control Safety Indicators: What is Achievable?

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    European Air Traffic Control is extremely safe. The drawback to this safety record is that it is very difficult to estimate what the ‘underlying’ accident rate for mid-air collisions is now, or to detect any changes over time. The aim is to see if it possible to construct simple ATC safety indicators that correlate with this underlying accident rate. A perfect indicator would be simple to comprehend and capable of being calculated by a checklist process. An important concept is that of ‘system control’: the ability to determine the outcome against reasonably foreseen changes and variations of system parameters. A promising indicator is ‘Incident Not Resolved by ATC’, INRA, incidents in which the ground ATC defences have been ‘used up’. The key question is: if someone says he or she knows how to make a good estimate of the underlying accident rate, then how could this claim be tested? If it correlates very well with INRA, then what would be the argument for saying that it is a better indicator

    London’s foundations protecting the geodiversity of the capital

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    This report describes a geodiversity audit of London commissioned by a partnership led by the Greater London Authority (GLA), which includes the British Geological Survey (BGS), Natural England, Government Office for London, London Biodiversity Partnership, London Borough of Lambeth, Harrow and Hillingdon Geological Society, South London London RIGS Groups, Hanson UK and Queen Mary College, University of London. The project was funded by an Aggregates Levy Sustainability Fund grant from Natural England plus additional support from the GLA, BGS and Natural England London Region. The audit began with a review of the available geodiversity documentation for London including: BGS field maps, databases and publications; Regional Important Geological Sites (RIGS) Group information; Natural England Sites of Special Scientific Interest (SSSI) and Geological Conservation Review (GCR) documentation; and documentation and data from the GLA and London Boroughs. An initial list of around 470 sites with potential for geodiversity value was compiled from this information. This list was then narrowed down to 100 for further assessment by exporting site locations to a GIS and cross-checking against digital aerial photography backed up by BGS staff local geological expertise. Using the procedure set out in this report field auditing was carried out by BGS staff and the South London RIGS Group between November 2007 and April 2008. From the list of 100 sites, 35 sites were found to be suitable for detailed auditing. Harrow and Hillingdon Geological Society audited a further site in November 2008, bringing the total to 36 sites. Using the criteria set out in this report 14 of the 36 sites are recommended for designation as Regionally Important Geological/geomorphological Sites (RIGS) in borough Local Development Documents. Of the 33 London boroughs, RIGS are recommended in eight, with five in Bromley, three in Croydon and one each in Lewisham, Ealing, Greenwich, Harrow, Hillingdon and Bexley. Using the criteria set out in this report 15 of the 36 sites have the potential to be designated as Locally Important Geological Sites (LIGS). These sites are located in nine boroughs, three in Waltham Forest, two in Bromley, two in Islington and one each in Barnet, Lewisham, Redbridge, Wandsworth, Southwark and Sutton. Planning proposals should have regard to geodiversity in order to implement strategic and local policies. Sites should be protected, managed and enhanced and, where ppropriate, new development should provide improvements to the geodiversity value of a site. This can include measures that promote public access, study, interpretation and appreciation of geodiversity. In addition to individual sites of geodiversity interest, Greater London has distinctive natural landscapes shaped by geological processes, such as undulating chalk downlands with dry valleys in south London, and river terraces forming long flat areas separated by steeper areas of terrace front slopes. This natural topographic geodiversity underlying London should be understood, respected and only altered in that knowledge with full knowledge of it origin and form. Planners are encouraged to use authentic contouring in restoration work and new landscaping schemes, maintain the contributions of natural topography, rock outcrops, landscape features, and to maintain soil quality, quantity and function

    The requirements of the airworthiness of aircraft

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    CĂ­lem tĂ©to prĂĄce je zjistit poĆŸadavky a postupy pro zĂ­skĂĄnĂ­ a zachovĂĄnĂ­ osvědčenĂ­ letovĂ© zpĆŻsobilosti letadel a vĂœrobkĆŻ letadlovĂ© techniky v rozsahu civilnĂ­ho letectvĂ­. VyĆĄetƙovanĂ© poĆŸadavky zahrnujĂ­ normy tĂœkajĂ­cĂ­ se poĆŸadavkĆŻ na letovou zpĆŻsobilost pƙes nĂĄvrh, vĂœrobu a provoz letadlovĂ© techniky.The focus of this study is to investigate the requirements and procedures for obtaining and maintaining a certificate of airworthiness of aircraft and aeronautical products within the scope of civil aviation. The requirements investigated include the standards regarding airworthiness requirements for large airplanes, helicopters, small airplanes, engines, and propellers. The procedures for certification and continuing airworthiness throughout the design, production and operating life of an aircraft are explained.

    Risk analysis of LPG tanks at the wildland-urban interface

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    In areas of wildland-urban interface (WUI), especially residential developments, it is very common to see liquefied petroleum gas (LPG) tanks, particularly with a higher ratio of propane, in surface installations serving homes. The most common tanks are between 1 and 5 m3 of capacity, but smaller ones of less than 1 m3 are more frequent. In case of accident, installations may be subject to fires and explosions, especially in those circumstances where legal and normative requirements allow very close exposure to flames from vegetable fuel near LPG tanks. In this project, it is intended to do a comprehensive diagnosis of the problem, addressing the compilation of information on real risk scenarios in historical fires. First, a preliminary presentation of the properties and characteristics of liquefied petroleum gas will be exposed. Its physical and chemical properties, production methodology, pressure and temperature diagrams and important considerations will be defined when using this type of substances in a storage tank of a certain volume. Next, a review of the situation of the existence of LPG tanks in the urban forest interfaces will be exposed. In this case, the main accidents caused by problems with the storage of LPG will be analyzed taking into account the relevance of BLEVE events in this type of incidents. To do this, the main scenarios that could take place in the event of a fire will be presented. Next, the existing legislation on the storage of LPG in these environments in some Mediterranean countries will be studied. In order to develop a comprehensive analysis, the main safety measures and distances will be considered, as well as the awareness of the possibility of vegetation material in the vicinity of LPG storage tanks, which is the main problem that will arise in a possible BLEVE scenario in case of fire. To finalize and facilitate understanding, a comparative table will be included with the aim of visualizing the main advantages and legislative deficiencies between the different countries. Following, the state of the art in terms of modelling LPG accidents at the WUI will be reviewed. Trying to simulate and predict this type of scenarios, it will see the models normally chosen to obtain the tolerable values selected and the answers obtained in each case. Finally, several fire scenarios will be simulated by means of a CFD tool (FDS, Fire Dynamics Simulator). In these simulations, the wind velocity and the distance of the combustible vegetal mass to the tank will be controlled in a WUI fire in which there is a tank of fixed dimensions. The temperature and the heat flow in each of the scenarios will be obtained, and the differences among the location of the sensors and the characteristics of the scenario will be analyzed. As a conclusion, it has been observed that there is a great amount of variables that are not contemplated by the regulatory organisms and that the existing legislation does not guarantee the safety of the population in this type of environment. From the simulations results, variables as temperature should be studied for further characterizations

    Design and Performance of Deep Excavations in Soft Clays

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    The paper discusses major design aspects related to deep excavations in soft clays including; bottom heave stability; deformations and loads on the supporting structure; methods to improve stability and limit displacements; lessons learned from failures; and fi-nally design principles and safety aspects. The various issues are illustrated by both parametric finite element studies and experiences gained from specific case histories. The results show a strong correlation between bottom heave stability, loads and dis-placements, and significant arching effects when the bottom heave safety factor is low. 2 and 3D FEM analyses confirm the applicability of traditional limit equilibrium bottom heave stability analyses, provided a search for critical failure surface is made and toe penetration of the supporting wall is accounted for. A concept based on using diaphragm wall with cross walls below the base is documented to be particularly effective in improving stability and limiting displacements. Ground improvement by deep mixing or jet-grouting has also been extensively used for this purpose and provides versatile design options. Some lessons learned from failures are highlighted and measures to avoid failures discussed. It is recommended to use continuum type FEM programs for de-sign, but their use require a good understanding of soil models to be used in the analyses. It is observed that soil parameters for use in design are often based on rather poor and rudimentary soil investigations, an issue which it is of prime importance for the geotechnical profession to face up to. When using ULS safety principles in design, the use of factored strengths may lead to un-reasonable design loads. FEM based design analyses should therefore be based on using slightly conservative characteristic strength and stiffness values. The resulting characteristic loads in the support structure must then be multiplied with an appropriate load factor to arrive at the design loads

    Prediction of dynamic pairwise wake vortex separations for approach and landing

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    Design and performance of the Wake Vortex Prediction and Monitoring System WSVBS are described. The WSVBS has been developed to tactically increase airport capacity for approach and landing on single runways as well as closely-spaced parallel runways. It is thought to dynamically adjust aircraft separations dependent on weather conditions and the resulting wake vortex behavior without compro-mis>ing safety. Dedicated meteorological instrumentation and short-term numerical terminal weather prediction provide the input to the prediction of wake-vortex behavior and respective safety areas. LIDAR monitors the correctness of WSVBS predictions in the most critical gates at low altitude. The WSVBS is integrated in the arrival manager AMAN of DLR. Performance tests of the WSVBS have been accomplished at Frankfurt airport in winter 2006/07 and at Munich Airport in summer 2010. Aircraft separations for landings on single runways have been compared employing the concepts of either heavy-medium weight class combinations or dynamic pairwise separations where individual aircraft type pairings are considered. For the very conservative baseline setup of the WSVBS the potential capacity gains of dynamic pairwise operations for single runways appear to be very small. On the other hand, the consideration of individual aircraft types and their respective wake characteristics may almost double the fraction of time when radar separation could be applied
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