1,726 research outputs found

    Self Piercing Riveting for Metal-Polymer Joints

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    Self-Piercing Riveting (SPR) is a sheet metal joining technique based on the insertion of a rivet into two or more sheets, with no preparatory hole. This process has gained wide diffusion in the automotive industry, due to the increasing use of materials alternative to steel, that are difficult or impossible to join with traditional techniques. In particular, polymeric materials are becoming increasingly used, due to their favorable weight/strength ratio. This paper reports the results of experimental investigations, aimed at identifying the variables affecting the mechanical characteristics of mixed metal-plastic joints. A statistic model for the optimization of the geometrical parameters has been computed. The paper demonstrates that self-piercing riveting appears competitive for metal/polymer junction. The results analyzed in light of statistical techniques show that some geometrical parameters affect joint performance more than others and can therefore be used as independent variables for joint performance optimizatio

    Three-dimensional fast electron transport for ignition-scale inertial fusion capsules

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    Three-dimensional hybrid PIC simulations are presented to study electron energy transport and deposition in a full-scale fast ignition configuration. Multi-prong core heating close to ignition is found when a few GA, few PW beam is injected. Resistive beam filamentation in the corona seeds the 3D current pattern that penetrates the core. Ohmic heating is important in the low-density corona, while classical Coulomb deposition heats the core. Here highest energy densities (few Tbar at 10 keV) are observed at densities above 200 g/cc. Energy coupling to the core ranges from 20 to 30%; it is enhanced by beam collimation and decreases when raising the beam particle energy from 1.5 to 5.5 MeV.Comment: 5 pages, 5 figure

    Fusion yield: Guderley model and Tsallis statistics

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    The reaction rate probability integral is extended from Maxwell-Boltzmann approach to a more general approach by using the pathway model introduced by Mathai [Mathai A.M.:2005, A pathway to matrix-variate gamma and normal densities, Linear Algebra and Its Applications}, 396, 317-328]. The extended thermonuclear reaction rate is obtained in closed form via a Meijer's G-function and the so obtained G-function is represented as a solution of a homogeneous linear differential equation. A physical model for the hydrodynamical process in a fusion plasma compressed and laser-driven spherical shock wave is used for evaluating the fusion energy integral by integrating the extended thermonuclear reaction rate integral over the temperature. The result obtained is compared with the standard fusion yield obtained by Haubold and John in 1981.[Haubold, H.J. and John, R.W.:1981, Analytical representation of the thermonuclear reaction rate and fusion energy production in a spherical plasma shock wave, Plasma Physics, 23, 399-411]. An interpretation for the pathway parameter is also given.Comment: 17 pages, LaTe

    A rare case of abdominal cocoon

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    Abdominal cocoon is a rare cause of intestinal obstruction usually diagnosed incidentally at laparotomy. It mani- fests by forming a membrane that typically encases the small bowel loops, leading to mechanical obstruction. Preoperative diagnosis is difficult. The etiology of this condition is not well understood; however, it is a form of chronic irritation and inflammation. METHOD: A 33 years old male, from Bangladesh, presented to our emergency department complaining of abdominal pain, nausea, and vomiting. CT abdomen shows a picture of intestinal obstruction at the level of the small intestine. Intraoperative findings showed encapsulation of small bowel by a dense whitish membrane as a cocoon. Histological exam- ination showed a granulomatous peritonitis and Ascaris Lumbricoides in the bowel resected. RESULTS AND CONCLUSIONS: The preoperative diagnosis of abdominal cocoon is difficult and hence, the diagnosis is usu- ally confirmed by laparotomy. Surgery remains the cornerstone in the management of abdominal cocoon. The pathogen- esis of abdominal cocoon remains elusive and has been associated with several conditions. The initial diagnosis of our patient was bowel obstruction from cocoon syndrome (CT and intraoperative findings) probably primitive, and only his- tologically proved granulomatous peritonitis associated with the presence of the parasite

    Detect-alert-deter system for enhanced biosecurity and risk assessment

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    This project developed a prototype of a machine vision-based surveillance system to enhance wildlife biosecurity by automatically detecting and deterring target wildlife. It was programmed to recognise and target ducks, which are avian influenza (AI) reservoirs and a potential biosecurity risk. Other species may also be reservoir or bridge species that spread AI, and therefore seasonal surveys of wild birds on and around meat chicken farms were undertaken as wild bird migration patterns vary for wild birds at different times of the year

    Probing the hydrogen melting line at high pressures by dynamic compression

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    We investigate the capabilities of dynamic compression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen is constructed. The results show that the melting line up to its maximum as well as the transition from molecular fluids to fully ionized plasmas can be tested with the beam parameters soon to be available. We demonstrate that x-ray scattering can distinguish between phases and dissociation states

    Co-Occurrence and Characteristics of Patients With Axial Spondyloarthritis Who Meet Criteria for Fibromyalgia : Results From a UK National Register

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    The British Society for Rheumatology (BSR) Biologics Register in Ankylosing Spondylitis is funded by the BSR and they have receive funds for this from Pfizer, AbbVie and UCB. These companies receive advance copies of manuscripts and can provide comments but have no input into determining the topics for analysis, publication and no input into the work involved in this analysis. This analysis is part-funded by Arthritis Research UK (Grant No: 21378)Peer reviewedPublisher PD

    Self-consistent numerical dispersion relation of the ablative Rayleigh-Taylor instability of double ablation fronts in inertial confinement fusion

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    The linear stability analysis of accelerated double ablation fronts is carried out numerically with a self-consistent approach. Accurate hydrodynamic profiles are taken into account in the theoretical model by means of a fitting parameters method using 1D simulation results. Numerical dispersión relation is compared to an analytical sharp boundary model [Yan˜ez et al., Phys. Plasmas 18, 052701 (2011)] showing an excellent agreement for the radiation dominated regime of very steep ablation fronts, and the stabilization due to smooth profiles. 2D simulations are presented to validate the numerical self-consistent theory
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