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[en] Coolant rubber hoses for automobile radiators can be degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under thermal and mechanical loadings. In this study, for EPDM(ethylene-propylene diene monomer) rubber conventionally used as a radiator hose material the aging behaviors of the skin part due to thermo-oxidative and electro-chemical stresses were nondestructively evaluated. Through the thermo-oxidative aging test, it was shown that the surface hardness IRHD(International Rubber Hardness Degrees) of the rubber increased with a considerable reduction of failure strain. On account of the penetration of coolant liquid into the skin part the weight of rubber specimens degraded by electro-chemical degradation(ECD) test increased, whereas their failure strain and IRHD hardness decreased largely. The penetration of coolant liquid seemed to induce some changes in inner structure and micro hardness distribution of the rubbers. Consequently, EPDM rubbers degraded by thermo-oxidative aging and ECD could be characterized nondestructively by micro-hardness and chemical structure analysis methods.
[en] MHD waves and instabilities in a collisionless anisotropic-pressure plasma are analyzed in an anisotropic MHD model based on the 16-moment approximation, and the results are found to agree well with those obtained in the low-frequency limit of the kinetic model. It is shown that accounting for heat fluxes leads to an asymmetry in the phase velocities of the wave modes with respect to the heat flux direction and also to a strong interaction between the modes, especially between the backward ones (those that propagate in a direction opposite to that of the heat flux). A correct description of the mirror instability is given. The resonant interaction of three backward modes-fast acoustic, fast magnetosonic, and slow acoustic-under the conditions for the onset of the classical firehose instability triggers a new type of instability the growth rate of which is faster than the maximum growth rate of the conventional firehose instability. The results prove that, in contrast to the familiar Chew-Goldberger-Low approximate model, the anisotropic MHD approach provides a correct description of the large-scale dynamics of collisionless anisotropic plasmas (such as solar corona, solar wind, and ionospheric and magnetospheric plasmas).
[en] A method is proposed for determining the throughput of a hose valve in systems for regulating the pressure and stabilizing the speed of viscous liquid fluxes in a pipe. The static and dynamic characteristics are determined for valves with different parameters.
[en] Problems that appear in a company that produces refined sugar, the production floor has not reached the level of critical machine availability because it often suffered damage (breakdown). This results in a sudden loss of production time and production opportunities. This problem can be solved by Reliability Engineering method where the statistical approach to historical damage data is performed to see the pattern of the distribution. The method can provide a value of reliability, rate of damage, and availability level, of an machine during the maintenance time interval schedule. The result of distribution test to time inter-damage data (MTTF) flexible hose component is lognormal distribution while component of teflon cone lifthing is weibull distribution. While from distribution test to mean time of improvement (MTTR) flexible hose component is exponential distribution while component of teflon cone lifthing is weibull distribution. The actual results of the flexible hose component on the replacement schedule per 720 hours obtained reliability of 0.2451 and availability 0.9960. While on the critical components of teflon cone lifthing actual on the replacement schedule per 1944 hours obtained reliability of 0.4083 and availability 0.9927. (paper)
[en] The plasma current decay time constant is predicted to be short compared to the pulse length and so self-focusing is predicted for most of the beam pulse. Four- pulse beam envelopes for a high dose case require mitigation, those for a low dose case do not. Methods of mitigation are summarized. Hose instability growth in the plume length is predicted to be minimal
[en] The Plasma Physics Division of the Naval Research Laboratory has been performing research into the propagation of high current electron beams for 20 years. Recent efforts have focused on the stabilization of the resistive hose instability. Experiments have utilized the SuperIBEX e-beam generator (5-MeV, 100-kA, 40-ns pulse) and a 2-m diameter, 5-m long propagation chamber. Full density air propagation experiments have successfully demonstrated techniques to control the hose instability allowing stable 5-m transport of 1-2 cm radius, 10-20 kA total current beams. Analytic theory and particle simulations have been used to both guide and interpret the experimental results. This paper will provide background on the program and summarize the achievements of the NRL propagation program up to this point. Further details can be found in other papers presented in this conference
[en] A general method is proposed for investigating stability of greatly extended stellar systems, particularly, bars and bridges between galaxies. Flexural oscillations of extended gravitating systems, which may be responsible for possible development of a hose instability, are considered in detail. The problem reduces to the solution of a linearized system of the Vlasov equations, involving the kinetic equation and the Poisson equation. It was demonstrated that non-rotating systems extended greatly enough, are always stable. The stabilizing effect of various factors is evaluated
[en] The original calculation (1975-76) of an electromagnetic mechanism for beam-channel tracking is presented. The system model is not realistic because only a flat profile channel which completely encloses the beam is considered. However, a clear demonstration of the existence of a tracking force is made, as a point of departure for the more recent studies which incorporate a realistic model of the beam head and conductivity profile
[en] A relativistic electron beam propagating through an annular plasma sheath is subject to a transverse plasma-electron coupled electrostatic instability. From the linearized fluid equations, the beam-sheath interaction is resolved into three coupled equations. The corresponding wakefield is computed and the asymptotic linear evolution is noted. For illustration, numerical examples are given for a plasma accelerator employing such a sheath. While the coasting beam scalings are quite severe at low energy, single-bunch instability growth can in fact be reduced to nil, for a very high-gradient accelerator
[en] Pinched propagation of intense relativistic electron beams occurs in several distinct pressure regimes. In low density gases (∼ 1-100 mtorr), the beam propagates in the ion-focused regime (IFR). The beam ionizes the neutral gas, and plasma electrons are ejected, leaving behind a positive ion column which pinches the beam electrostatically. At gas densities near 1 atm, the beam-generated plasma is resistive and the pinch effect is provided by the self-magnetic field of the beam. Beam transport experiments in both regimes have been performed on the Advanced Test Accelerator (ATA) at Lawrence Livermore National Lab. and on SuperIBEX at the Naval Research Lab. IFR methods have been employed in both experiments to transport the beam prior to injection into the air and to introduce a head-to-tail taper in the beam radius. IFR simulations have shown how the resulting beam radius and emittance profiles are influenced by gas density, chamber dimensions and entrance and exit foils. Beam propagation in dense gas is subject to disruption by the resistive hose instability. However, both experiments and simulations have shown that the emittance variation introduced by IFR transport can substantially reduce the growth of the hose instability. Both experiments have also propagated beams in reduced-density channels. Simulations predict that the channel may in some cases produce a moderate stabilizing and tracking effect arising from plasma currents flowing at the edge of the channel