Propellant subsystem design for hypersonic cruiser exploiting liquid hydrogen

The possibility of establishing a new paradigm for commercial aviation towards high-speed flight in the next decades shall be inevitably preceded by the increase of Technology Readiness Level for those relevant enabling technologies associated to propulsion, thermal management and on-board subsystems, with particular attention also to environmental sustainability and economic viability of the proposed concepts. New design methodologies for both aircraft and on-board subsystems design shall then be based on holistic approaches able to catch the strong interactions between vehicle configuration, mission and subsystems architecture, which characterize high-speed aircraft layouts. This paper proposes a methodology for the preliminary sizing of propellant subsystems for liquid hydrogen powered hypersonic cruisers. Making benefit of traditional approaches, the process aims at introducing new design aspects directly connected to the peculiar multifunctional architecture of on-board subsystems for high-speed vehicles, so to be able to include additional analyses in early design stages, especially in case of high level of on-board integration. Notably, impact of requirements for Center of Gravity control, thermal, and, in general, energy management are considered as integral part of the method, with crucial implications on architecture selection. After the introduction of design algorithms for subsystem sizing, the STRATOFLY MR3 hypersonic cruiser is taken as reference case study in order to provide a practical example of application of the proposed approach on a highly integrated platform

Systems Engineering and Its Application to Industrial Product Development

PREFACE : Mastering the complexity of innovative systems currently looks a challenging goal of design and product development as well as embedding a suitable degree of smartness in devices, machines and equipment to make them able of adapting their operation to variable conditions or effects of a harsh environment. This goal is achieved through a continuous monitoring of the system in service, an effec-tive control of its behavior and a wide connectivity towards many other systems. Only an effective system design and manufacture, able to cover all the required actions, can assure this kind of assessment overall the life cycle since a very ear-ly concept of the product to a full disposal and service. Complexity makes hard managing the product development, because of the number of functions, subsystems, components and related interfaces usually in-volved, like in motor vehicles, robots, railways systems, aircrafts and spacecrafts as well as in large industrial manufacturing systems or very innovative microsys-tems and bioinspired devices. A crucial issue in this activity is performing a bright and complete elicitation of requirements, which need to be fully and suit-ably allocated to the system components, through a clear traceability, especially in systems produced as a result of material processing and assembling of parts. Moreover, the product must fit the requirements associated to some customer needs, innovation targets, and technical standards and be compatible with the manufacturer’s capabilities. As it looks clear from the current state–of–art, since several years the Systems Engineering assures a suitable answer to the needs above mentioned. It provides a methodology to drive the product lifecycle assessment that is implemented through a well defined process, being based on some specific and graphical lan-guages and even formalized in several tools enabling the required analyses, tak-ing advantage of the capabilities of some dedicated commercial software. Those contents lead to create a platform, consisting of a sort of tools chain, which might be used and shared among different industrial and professional partners to digitalize both the information and even the whole industrial product develop-ment, as far as the current strategy referred to as “Industry 4.0 / The Factory of the Future” brightly suggests and supports. The so–called Model Based Systems Engineering (MBSE) is then successfully proposing an effective and modern al-ternative to the document-based approach, using data models as a main element of the design process. Some technical standards already drive the user in imple-menting the Systems Engineering, thus leading to develop a systematic approach the design aimed at satisfying the customer needs. Suitable capabilities in the manufactured system are assured by the so–called architectural frameworks, which support the system development and integration. The Model Based Systems Engineering allows proceeding with a modeling activity which investigates requirements, behavior and architecture through a combined operational, functional and logical analysis, being linked and interop-erated with a mathematical and physical modeling, which is typically more known and widely used within the industrial engineering. A full integration of all the activities of the Product Lifecycle Management (PLM) is currently going on, to include the system architecture definition and its Application Lifecycle Man-agement (ALM) as well as the Product Data Management (PDM), i.e. the design activity together with the tasks of production, testing, homologation and service. A recognized standard certification to qualify the Systems Engineer is even available as the International Council on Systems Engineering (INCOSE) pro-vides. The scenario above described is strongly integrated with the increasing devel-opment of both the network and the cyber–physical systems, for a fully distribut-ed connectivity, to be exploited in advanced smart systems and devices as well as in intelligent manufacturing, according to the most recent strategies of innova-tion as the “Industry 4.0” initiative and the “Lean manufacturing” idea. Simulta-neously, the system smartness and connectivity together increase the demand of data transmission and elaboration, thus linking this topic to the technology of big data management, whilst they benefit of the progress in information technology, through a secure cloud based on the network. The context just described motivates the fast diffusion of the Model Based Systems Engineering as a tool for innovating all the production processes. The increasing demand of specialized software and of educational activities as well as the number of workshops and conferences focused on this topic confirm this trend. However, it might be remarked that several contributions to the literature about the Systems Engineering widely grew up during the last years, thus making the Reader sometimes confused, especially when approaching this topic at first. The Systems Engineering topics are so many that it looks rather difficult mas-tering its skills, without a preliminary classification of contents. Technical do-mains involved are mainly those of engineering and computer science, although many other ones play the role of a daily user of this methodology. According to the most recent development of the Systems Engineering, whose typical applica-tion fields were the software and electronic systems even for space missions, the current focus consists of several industrial systems, being gradually innovated by introducing the tailored solutions of mechatronics. It is worthy noticing that a significant advancement was introduced between the very early implementation of the Systems Engineering and its recent evolution, since several new applica-tions are focused on the production of systems, which need to be manufactured through a material processing. Usually, they exhibit some attributes related both to their physical nature and to the functions performed, thus requiring to model both their functional and physical behaviors together. This need is changing the scenario of the typical applications of the Systems Engineering as software de-sign. This handbook expressively avoids to cover all the typical contents of the spe-cialized literature of the Model Based Systems Engineering, whilst is aimed at making easier a first approach to this topic and sharing a preliminary experience performed by the authors within some industrial domains, by proceeding in the modeling activity in a real industrial environment. The main goal is drawing a sort of simple and hopefully clear roadmap in modeling and developing the in-dustrial and material systems and in implementing the Systems Engineering, par-ticularly in the design activity. Therefore, the target audience of this handbook includes professional engineers, scientists and students dealing with the Applica-tion Lifecycle Management and the system architecture assessment, more than the Product Data Management or the whole Product Lifecycle Management. The approach followed is that of introducing some examples of implementa-tion of the Systems Engineering, by proceeding step by step from the screening of needs and the elicitation of requirements till a synthesis of the system design. Each action will be referred to the literature, related to the implementation of the Systems Modeling Language or SysML and to the use of some tools available on market, thus highlighting benefits, drawbacks and current limitations of some dedicated software or even of some proposed methodologies. Several comments will be provided to describe the troubles shared among some users of the Sys-tems Engineering as they were detected in daily practice by the authors. They wish that this handbook could briefly and gradually provide the Reader with a preliminary guideline to approach professionally the Model Based Systems En-gineering, by understanding its main contents and applying it to the industrial environment. As a desired result, this work might be considered as an integration of some textbooks of Machine Design, and it is aimed at completing the education within Engineering Design or at simply providing a friendly introduction to the Systems Engineerin

Innovative Multiple Matching Charts approach to support the conceptual design of hypersonic vehicles

Several well-established best practices and reliable tools have been developed along the years to support aircraft conceptual and preliminary design. In this context, one of the most widely used tool is the Matching Chart (MC), a graphical representation of the different performance requirements (curves representing the thrust-to-weight ratio (T/W) requirement as function of the wing loading (W/S)) for each mission phase. The exploitation of this tool allows the identification of a feasible design space as well as the definition of a reference vehicle configuration in terms of maximum thrust, maximum take-off weight, and wing surface since the very beginning of the design process. Although the tool was originally developed for conventional aircraft, several extensions and updates of the mathematical models have been proposed over the years to widen its application to innovative configurations. Following this trend, this paper presents a further evolution of the MC model to support the conceptual design of high-speed transportation systems, encompassing supersonic and hypersonic flight vehicles. At this purpose, this paper reports and discusses the updates of the methodology laying behind the generation of the MC for high-speed transportation. Eventually, the results of the validation of the updated methodology and tool are reported, using as case study, the STRATOFLY MR3 vehicle configuration, a Mach 8 antipodal civil transportation system, currently under development within the H2020 STRATOFLY project

Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector

Measurement of the charge asymmetry in dileptonic Decays of top quark pairs in pp collisions at √ s = 7 TeV using the ATLAS detector

A measurement of the top-antitop (tt) charge asymmetry is presented using data corresponding to an integrated luminosity of 4.6 fb −1 of LHC pp collisions at a centre- of-mass energy of 7 TeV collected by the ATLAS detector. Events with two charged leptons, at least two jets and large missing transverse momentum are selected. Two observables are studied: A tt/C, based on the reconstructed tt final state. The asymmetries are measured to be A ll/C = 0.024 +/- 0.015 (stat.) +/- 0.009 (syst.) Att/C = 0.021 +/- 0.025 (stat.) +/- 0.017 (syst.) The measured values are in agreement with the Standard Model predictions

Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

This article reports on a search for dark matterpair production in association with bottom or top quarks in20.3fb−1ofppcollisions collected at√s=8TeVbytheATLAS detector at the LHC. Events with large missing trans-verse momentum are selected when produced in associationwith high-momentum jets of which one or more are identifiedas jets containingb-quarks. Final states with top quarks areselected by requiring a high jet multiplicity and in some casesa single lepton. The data are found to be consistent with theStandard Model expectations and limits are set on the massscale of effective field theories that describe scalar and tensorinteractions between dark matter and Standard Model par-ticles. Limits on the dark-matter–nucleon cross-section forspin-independent and spin-dependent interactions are alsoprovided. These limits are particularly strong for low-massdark matter. Using a simplified model, constraints are set onthe mass of dark matter and of a coloured mediator suitableto explain a possible signal of annihilating dark matter

Measurement of the top pair production cross section in 8 TeV proton-proton collisions using kinematic information in the lepton plus jets final state with ATLAS

A measurement is presented of the $t\bar{t}$ inclusive production cross-section in $pp$ collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV using data collected by the ATLAS detector at the CERN Large Hadron Collider. The measurement was performed in the lepton+jets final state using a data set corresponding to an integrated luminosity of 20.3 fb$^{-1}$. The cross-section was obtained using a likelihood discriminant fit and $b$-jet identification was used to improve the signal-to-background ratio. The inclusive $t\bar{t}$ production cross-section was measured to be $260\pm 1{\textrm{(stat.)}} ^{+22}_{-23} {\textrm{(syst.)}}\pm 8{\textrm{(lumi.)}}\pm 4{\mathrm{(beam)}}$ pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of $253^{+13}_{-15}$ pb. The $t\bar{t}\to (e,\mu)+{\mathrm{jets}}$ production cross-section in the fiducial region determined by the detector acceptance is also reported.Comment: Published version, 19 pages plus author list (35 pages total), 3 figures, 2 tables, all figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2013-06