59,454 research outputs found
Navier-Stokes Equations for Generalized Thermostatistics
Tsallis has proposed a generalization of Boltzmann-Gibbs thermostatistics by
introducing a family of generalized nonextensive entropy functionals with a
single parameter . These reduce to the extensive Boltzmann-Gibbs form for
, but a remarkable number of statistical and thermodynamic properties have
been shown to be -invariant -- that is, valid for any . In this paper, we
address the question of whether or not the value of for a given viscous,
incompressible fluid can be ascertained solely by measurement of the fluid's
hydrodynamic properties. We find that the hydrodynamic equations expressing
conservation of mass and momentum are -invariant, but that for conservation
of energy is not. Moreover, we find that ratios of transport coefficients may
also be -dependent. These dependences may therefore be exploited to measure
experimentally.Comment: RevTeX and epsf macros required, 19 pages, 8 figure
Velocity measurements in regions of upstream influence of a body in aligned-fields MHD flow
Experiments are described in which velocities were measured ahead of a semi-infinite Rankine body moving parallel to a uniform magnetic field in a conducting fluid. The flow disturbance in front of the body is found to increase in length as N½, where N is the interaction parameter. In most of the experiments this parameter was varied from 4 to about 50. Measurements made along the axis of symmetry in the flow show that there is a relatively short region of stagnant fluid directly ahead of the body. The major part of the disturbance is found to consist of a much longer region in which the flow undergoes transition from
conditions in the free stream to conditions near the body. Velocity profiles across the flow in this region show that for increased N, at a fixed distance ahead of the
body, the velocity defect increases and the disturbance becomes more confined radially. Although the radial gradients in the flow increase with N, they are
found to be much smaller than would be expected in a flow containing thin current layers. A physical model of the flow which has currents and pressures consistent with these results is discussed
Estimation of variance by a recursive equation
Recursive equation for estimating variance of sequential random number
Measurements of dust on Mars to be obtained from upcoming missions
Measurements of dust on the Mars surface and in its atmosphere will be made from several upcoming missions. The best defined missions are Mars Observer, the Soviet Mars 94 mission, and the Mars Environment Survey (MESUR) mission. A discussion is presented of what measurements pertaining to airborne or surface dust will be made and what properties can be inferred from them. The payloads for the latter two missions are not yet determined. In all cases, only that information which pertains to dust is included; each mission contains additional instruments that provide no information on this topic. Following the discussion of individual instruments is a summary of the types of measurements and observations that will be made from the ensemble collection of instruments and missions, and a brief discussion of the types of measurements of dust which will not be made
The Net Neutrality Debate: Twenty Five Years after United States v. AT&T and 120 Years after the Act to Regulate Commerce
Apparent ignorance of more than a century of economic history now threatens the competitive constitution of the Internet under the guise of "net neutrality." Net neutrality is a slogan that stands for the proposition that the Internet and physical means of access to it should be available to all on uniform, non-discriminatory terms. Proponents of net neutrality fear, first, that access to bottlenecks, such as the "last mile" to the home, will be monopolized and second, that the successful monopolist will seek to favor its own vertical services by excluding or disfavoring others. Net neutrality is their answer to these threats. But the architects of the concept of net neutrality have simply resurrected the traditional na
The connector space reduction mechanism
The Connector Space Reduction Mechanism (CSRM) is a simple device that can reduce the number of electromechanical devices on the Payload Interface Adapter/Station Interface Adapter (PIA/SIA) from 4 to 1. The device uses simplicity to attack the heart of the connector mating problem for large interfaces. The CSRM allows blind mate connector mating with minimal alignment required over short distances. This eliminates potential interface binding problems and connector damage. The CSRM is compatible with G and H connectors and Moog Rotary Shutoff fluid couplings. The CSRM can be used also with less forgiving connectors, as was demonstrated in the lab. The CSRM is NASA-Goddard exclusive design with patent applied for. The CSRM is the correct mechanism for the PIA/SIA interface as well as other similar berthing interfaces
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