Innovative all composite multi-pultrusion truss system for stressed arch deployable shelters

Trusses are one of the successful structural forms that have been utilised, at extended scale, since the nineteen century. Fibre composite materials are relatively new to civil engineering applications. The increased interest in using composites in civil applications can be attributed to advantages when compared to other construction materials that offset their associated costs. Using conventional approaches for truss systems in composite materials can undermine their efficiency. This is mainly due to concentration of stresses at connections which usually govern the truss design. The Military Modular Shelter System (M2S2) initiative is a research project that aims to develop a fibre composite re-deployable arched shelter system with rigid PVC or fabric cladding. The main frames are formed from modular fibre composite panels that are connected and stressed into position by prestressing cables. Different geometries can be obtained using this system by changing the number of panels per frame and the packer sizes between panels. This paper presents the development and testing of innovative fibre composite truss modules that were investigated as part of this project. The truss system is based on using multi-pultrusion sections for the chord and vertical members. Truss bracing is provided by a double skin laminated web. This structure offers many advantages including semi-ductile failure that occurred outside the joint area and ease of manufacturing. In spite of being developed for the M2S2 system, the concept is similarly applicable as a general purpose truss system

Aubry transition studied by direct evaluation of the modulation functions of infinite incommensurate systems

Incommensurate structures can be described by the Frenkel Kontorova model. Aubry has shown that, at a critical value K_c of the coupling of the harmonic chain to an incommensurate periodic potential, the system displays the analyticity breaking transition between a sliding and pinned state. The ground state equations coincide with the standard map in non-linear dynamics, with smooth or chaotic orbits below and above K_c respectively. For the standard map, Greene and MacKay have calculated the value K_c=.971635. Conversely, evaluations based on the analyticity breaking of the modulation function have been performed for high commensurate approximants. Here we show how the modulation function of the infinite system can be calculated without using approximants but by Taylor expansions of increasing order. This approach leads to a value K_c'=.97978, implying the existence of a golden invariant circle up to K_c' > K_c.Comment: 7 pages, 5 figures, file 'epl.cls' necessary for compilation provided; Revised version, accepted for publication in Europhysics Letter

THE EFFECT OF CORE ARCHITECTURE ON THE BEHAVIOUR OF SANDWICH COLUMNS UNDER EDGEWISE COMPRESSION LOADING

ABSTRACT Sandwich structures are a form of construction that offers high performance and low-weight. This type of construction became popular by the mid of the twenty century where different metallic faces and core materials were used for the construction of aircrafts and marine vessels. The development of high-strength, high-modulus, light-weight fibres and new forms of core materials has opened a new horizon for sandwich structures. Using sandwich structures for columns was investigated by different researchers. However, none of the located literature reported using strong-weak core (mixed-core) materials in sandwich columns. To investigate the effect of using mixed-core on the column behaviour was investigated by testing five sets of prototype columns under edgewise compression. The column cores were made of PVC low-density foam, end-grain balsa wood or a combination of both materials. The column skins were laminated by using glass/epoxy composites. The test results showed that the mixed-core can lead to having a failure mode that has not been reported previously. This paper presents the experimental work conducted in testing these columns. It highlights the effect of core structure on the failure mode and capacity of the sandwich columns

Innovative Piloting Technique for a Semi-Autonomous UAV Lighter-Than-Air Platform Simulator

UAS design has in these years reached a point in which trends and objectives are well beyond the actual test capabilities. The tendency of the past to build and test has clearly been overridden by new design concepts for many reasons, one of these being the scarce or null possibility of testing safety-critical systems such as UAV systems. This is the context in which the Elettra-Twin-Flyer (ETF) Simulator is constantly upgraded and rearranged to incorporate new features and more advanced capabilities. In this paper it is shown how the piloting modes have been differentiated, to improve the airship autonomy and allow path following operations. Innovative piloting tools have been introduced and a new Human-Machine-Interface has been proposed along

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Towards structured sharing of raw and derived neuroimaging data across existing resources

Data sharing efforts increasingly contribute to the acceleration of scientific discovery. Neuroimaging data is accumulating in distributed domain-specific databases and there is currently no integrated access mechanism nor an accepted format for the critically important meta-data that is necessary for making use of the combined, available neuroimaging data. In this manuscript, we present work from the Derived Data Working Group, an open-access group sponsored by the Biomedical Informatics Research Network (BIRN) and the International Neuroimaging Coordinating Facility (INCF) focused on practical tools for distributed access to neuroimaging data. The working group develops models and tools facilitating the structured interchange of neuroimaging meta-data and is making progress towards a unified set of tools for such data and meta-data exchange. We report on the key components required for integrated access to raw and derived neuroimaging data as well as associated meta-data and provenance across neuroimaging resources. The components include (1) a structured terminology that provides semantic context to data, (2) a formal data model for neuroimaging with robust tracking of data provenance, (3) a web service-based application programming interface (API) that provides a consistent mechanism to access and query the data model, and (4) a provenance library that can be used for the extraction of provenance data by image analysts and imaging software developers. We believe that the framework and set of tools outlined in this manuscript have great potential for solving many of the issues the neuroimaging community faces when sharing raw and derived neuroimaging data across the various existing database systems for the purpose of accelerating scientific discovery

Treatment-limiting decisions in patients with severe traumatic brain injury in the Netherlands

Introduction: Treatment-limiting decisions (TLDs) can be inevitable severe traumatic brain injury (s-TBI) patients, but data on their use remain scarce. Research question: To investigate the prevalence, timing and considerations of TLDs in s-TBI patients. Material and methods: s-TBI patients between 2008 and 2017 were analysed retrospecively. Patient data, timing, location, involvement of proxies, and reasons for TLDs were collected. Baseline characteristics and in-hospital outcomes were compared between s-TBI patients with and without TLDs. Results: TLDs were reported in 117 of 270 s-TBI patients (43.3%) and 95.9% of deaths after s-TBI were preceded by a TLD. The majority of TLDs (68.4%) were categorized as withdrawal of therapy, of which withdrawal of organ-support in 64.1%. Neurosurgical intervention was withheld in 29.9%. The median time from admission to TLD was 2 days [IQR, 0–8] and 50.4% of TLDs were made within 3 days of admission. The main reason for a TLD was that the patients were perceived as unsalvageable (66.7%). Nearly all decisions were made multidisciplinary (99.1%) with proxies involvement (75.2%). The predicted mortality (CRASH-score) between patients with and without TLDs were 72.6 vs. 70.6%. The percentage of TLDs in s-TBI patients increased from 20.0% in 2008 to 42.9% in 2012 and 64.3% in 2017. Discussion and conclusion: TLDs occurred in almost half of s-TBI patients and were instituted more frequently over time. Half of TLDs were made within 3 days of admission in spite of baseline prognosis between groups being similar. Future research should address whether prognostic nihilism contributes to self-fulfilling prophecies.</p