981 research outputs found
On the equilibrium problem and infinitesimal mechanisms of class theta tensegrity systems
No full textThis work presents a study on the equilibrium problem and the infinitesimal mechanisms of class θ= 1 tensegrity prisms. Local solutions of the self-equilibrium problem are numerically obtained through Newton-Raphson iterations. The presented results suggest that the analyzed structures can be usefully employed as building blocks of novel tensegrity metamaterials, due to their rich kinematic response and the considerably large number of infinitesimal mechanisms. © 2019 Author(s)
Full 3D CAD procedure for the speedy evaluation of the seismic vulnerability of masonry towers
No full textA very straightforward 3D CAD approach for the speedy evaluation of the seismic vulnerability of existing masonry towers is presented. The procedure requires only the detailed 3D geometric model of the structure and automatically calculates the collapse acceleration on a user defined failure mechanism. In this paper, few pre-assigned mechanisms are tested, as for instance vertical splitting, simple overturning at the base, rocking with inclined yield lines and combined rocking and vertical splitting. The restriction of the possible tower failure within such a few mechanisms grounds on previous numerical research in the field and post-earthquake surveys experience. In any case, any user can define his own mechanisms according to the specificity of the case-study under consideration, directly shaping distinct volumes inside the CAD software. The procedure is automatized and the direct application of the principle of virtual works-assuming that masonry behaves as a no-tension material-allows the immediate evaluation of the horizontal acceleration at collapse. The mechanism associated to the minimum acceleration, in agreement with the kinematic theorem of limit analysis, is that most probably would occur in reality during a seismic event. The approach allows a straightforward evaluation of the seismic vulnerability of a tower and can be used even by practitioners not familiar with advanced FE computations and limit analysis concepts, so adapting well to the heterogeneous community involved in cultural heritage preservation. The automatized procedure is applied in this paper to a historical tower located in central Italy, to show the capabilities of the approach. © 2019 Author(s)
The Arab peoples of T.E. Lawrence's Seven Pillars of Wisdom in the light of post-colonial theory
No full textIt can be said that The Seven Pillars of Wisdom is a work whose true potential has not yet been discovered. That the work presents itself to be of greater value than may have previously seemed goes without question. However, during the more than eighty years of its existence, it was the author and not the work that created major interest in the academic world. The complicated character of T.E. Lawrence offered itself to psycho-analyst interpretation and most critiques have been built on these premises. Other works have concentrated on major historical events in Lawrence's life creating thorough biographies and numbers of fascinating approaches, some more, some less misleading were created. However. The Seven Pillars of Wisdom (from henceforth "Seven Pillars") foremostly survived in the shadows of David Lean's film "Lawrence of Arabia" and it was only during the late seventies, that concentration on the Seven Pillars as a text had begun to be cultivated. Additionally, it has only been during the past few years that works by writers such as Gertrude Bell, T.E. Lawrence or Charles M. Doughty have begun to gain a larger public interest. The aim of this work, however, is not to analyse the historical purpose of Lawrence's presence in the Middle East, nor to align the Seven Pillars with historical facts. Such..
The Arab peoples of T.E. Lawrence's Seven Pillars of Wisdom in the light of post-colonial theory
No full textIt can be said that The Seven Pillars of Wisdom is a work whose true potential has not yet been discovered. That the work presents itself to be of greater value than may have previously seemed goes without question. However, during the more than eighty years of its existence, it was the author and not the work that created major interest in the academic world. The complicated character of T.E. Lawrence offered itself to psycho-analyst interpretation and most critiques have been built on these premises. Other works have concentrated on major historical events in Lawrence's life creating thorough biographies and numbers of fascinating approaches, some more, some less misleading were created. However. The Seven Pillars of Wisdom (from henceforth "Seven Pillars") foremostly survived in the shadows of David Lean's film "Lawrence of Arabia" and it was only during the late seventies, that concentration on the Seven Pillars as a text had begun to be cultivated. Additionally, it has only been during the past few years that works by writers such as Gertrude Bell, T.E. Lawrence or Charles M. Doughty have begun to gain a larger public interest. The aim of this work, however, is not to analyse the historical purpose of Lawrence's presence in the Middle East, nor to align the Seven Pillars with historical facts. Such..
Strategies and Practices of Trade Management for Phalaenopsis Varieties
No full text台灣蝴蝶蘭擁有多樣而豐富的種原，且在育種者的努力下，商業品種推陳出新，奠定了蝴蝶蘭產業行銷全世界的基石。然而，許多以往提升育種效率的核心種原或商業品種隨著時代的變遷而由市場上流失，並無一套完整的機制進行計畫性地蒐集與保存。另外，國內育種者生產規模以小型居多，無專業能力處理流程冗長的品種權申請與管理問題，容易因市場機制而廉售品種。因此，台灣的蝴蝶蘭育種要能保有以往領先地位，應成立蝴蝶蘭品種管理平台或成立法人機構辦理品種交易管理業務，統合品種之保存、寄賣、鑑價收購、試種、展示、行銷、智財佈局、侵權處理及資訊服務等業務於一身，協助產業站穩品種多樣性之核心價值，讓台灣成為全球蝴蝶蘭品種研發與種苗供應中心，有計畫地引領品種流行趨勢，形塑台灣蝴蝶蘭的國家品牌。
Due to the plenty bio-diversity of orchid germplasm resources in Taiwan, allowed breeders putting their efforts to create and release more than hundreds of new Phalaenopsis varieties in one year. The active breeding works resulted in a well-known Taiwan Phalaenopsis industry in the world. However, some of the so-called core varieties or important commercialized varieties lost as the time pass without any preservation. Otherwise, the domestic breeders mostly kept their varieties with small production scale and had not enough ability to deal with the long-term application process of variety rights resulting in selling their varieties at a low price in the trading market. Thus, if we want to maintain the previous leadership of Taiwan orchid breeding in Phalaenopsis industry in the world, we should set up orchid varieties management platform or establish a legal institution to handle variety trading management service which integrated the variety preservation, consignment, in view of the acquisition price, trying cultivation, display, marketing, intellectual property layout, infringement processing and information services, and other services in one. This will assist breeders to keep the core values of new varieties in Phalaenopsis industry in Taiwan, so that can let Taiwan become the world's developing and supplying centerof newPhalaenopsis varieties. At that time, we can afford to Taiwan Phalaenopsis country brand
Minimum MSE estimation of a regression model with fixed effects from a series of cross sections (Revised version)
No full textEstimation
Pathways to Industrial-Scale Fuel Out of Thin Air from CO<sub>2</sub> Electrolysis
No full textUsing renewable energy as an input, Power-to-X technologies have the potential to replace fossil fuels and chemicals with dense-energy carriers that are instead derived out of thin air. In this work, we put into context what the industrial-scale production of chemicals from ambient CO2 using CO2 electrolysis means in terms of future required operating conditions and the device and catalyst scales that will be needed for the technology to assume its role in our global energy system.Accepted Author ManuscriptChemE/Materials for Energy Conversion and StorageChemE/Transport Phenomen
Mechanical modeling of the bandgap response of tensegrity metamaterials
No full textWe investigate the acoustic band structure of tensegrity mass-spring chains as a function of the applied, local and global states of prestress. We first study the bandgap response of linear monoatomic chains, which show lumped masses connected to tensegrity prisms acting as mechanical springs. Next, we present a numerical study on the nonlinear wave dynamics of the examined systems in the geometrically nonlinear regime that is induced by the presence of moderately large relative displacements between the lumped masses. Such a study confirms the results of the linear analysis in the case of an elastically hardening system. © 2019 Author(s)
Optimising Landing-site Selection for ExoMars
No full textOnly 6 out of 16 missions to the surface of Mars have been successful, all have been NASA missions. The landing sites of all the successful missions have been carefully selected in a process where: 1) scientists propose candidate landing sites, 2) engineers check whether these sites allow for a safe landing, and 3) over a few iterations, the number of sites is brought down to the final site and a back-up. ExoMars will be the first lander to Mars designed by the European Space Agency. It will explore Mars in search of signs of past and present life. An extensive landing-site selection process is required to find a landing site that is safe from both an engineering perspective and that will help to answer the mission’s science objectives. This research has identified four developments that decrease the efficiency of the current landing-site selection process: 1) there is more and more data available on Mars, which makes combining and analysing all this data manually no longer possible; 2) the technical capabilities of the landing system are increasing, which makes a larger part of the surface available; 3) the questions posed in the scientific and exploration objectives become more and more specific, which sets more stringent requirements on where these questions can be answered; and 4) the Martian surface turned out to be more variable in composition than was previously thought. This study recommends a set of improvements in the form of a decision support system (DSS) that assists experts in the landing-site selection process. The DSS developed for this research includes two prototypes 1) a method that emulates the pattern recognition of a trained, terrain-analysis expert (i.e. a geologist) on a computer, called the terrain fingerprinting method (TFM); and 2) a platform that provides the interface through which all stakeholders in the landing site selection process (scientists, engineers, students, managers) can efficiently interact. This study concludes that I) the TFM can be used to find a landing site that optimises both the safety of the mission and the possibility for scientific return at the site. II) A central platform is required in order to empower the landing site selection community by sharing higher level data products, tools (e.g. TFM software tools), a forum, and documentation. III) The United States Geological Survey (USGS) is the central authority in the planetary sciences community in the USA providing standardisation support, the lack of such a central authority in Europe will negatively affect the process of landing-site selection by European scientists for all future planetary landers. And IV) for the various stakeholders to effectively collaborate and interact in the process of landing-site selection, standardisation of elements related to geographically referenced planetary data is essential.Astrodynamics and Satellite SystemsAerospace Engineerin
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