Composite piston

A composite piston structure is disclosed which provides a simple and reliable means for joining a carbon-carbon or ceramic piston cap with a metallic piston body. Attachment is achieved by means of a special geometry which compensates for differences in thermal expansion without complicated mechanical fastening devices. The shape employs a flange created by opposed frustoconical shapes with coincident vertices intersecting on the radial centerline of the piston in order to retain the piston cap. The use of carbon-carbon for the piston cap material allows a close fit between the piston and a cylinder wall, eliminating the need for piston rings. The elimination of extra mechanical parts of previous composite pistons provides a lightweight composite piston capable of extended high temperature operation

Radio pulsar timing observations for GRO

Gamma rays probably provide the best diagnostic tool for probing the enigmatic physics of pulsar magnetospheres. At present, however, only two pulsars - the young, nearby ones in the Crab and Vela X supernova remnants - are reliably detected at gamma-ray energies. With adequate radio observations to provide independent timing information, Gamma Ray Observatory should be able to detect a number of additional pulsars, and the results will be of great benefit in testing magnetospheric theories and models. Timing observations for this purpose were started at a number of radio observatories around the world. The general procedures being used are described. A status report on the work is given

The Adiabatic Motion of Outer Zone Particles in a Model of the Geoelectric and Geomagnetic Fields

Charged particle motion calculations from model of earths magnetospher

The latitude - local time dependence of low energy cosmic ray cut-offs in a realistic geomagnetic field

Latitude - local time dependence of low energy cosmic ray cut-offs in realistic geomagnetic fiel

Visual Performance on the Moon

Optical and photometric properties of lunar surface and implications for human visual performanc

Lusztig Induction, Unipotent Supports, and Character Bounds

Recently, a strong exponential character bound has been established in [3] for all elements $g \in \mathbf{G}^F$ of a finite reductive group $\mathbf{G}^F$ which satisfy the condition that the centraliser $C_{\mathbf{G}}(g)$ is contained in a $(\mathbf{G},F)$-split Levi subgroup $\mathbf{M}$ of $\mathbf{G}$ and that $\mathbf{G}$ is defined over a field of good characteristic. In this paper, assuming a weak version of Lusztig's conjecture relating irreducible characters and characteristic functions of character sheaves holds, we considerably generalize this result by removing the condition that $\mathbf{M}$ is split. This assumption is known to hold whenever $Z(\mathbf{G})$ is connected or when $\mathbf{G}$ is a special linear or symplectic group and $\mathbf{G}$ is defined over a sufficiently large finite field.Comment: 35 pages; v2. minor improvements to abstract and introduction; v3. further improvements to the exposition; v4. significant changes. Main result now works for special linear and symplectic groups. Added results on groups of type A generalising results of Hildebrand; v5. post referee repor

Metaphor, Objects, and Commodities

This article is a contribution to a symposium that focuses on the ideas of Margaret Jane Radin as a point of departure, and particularly on her analyses of propertization and commodification. While Radin focuses on the harms associated with commodification of the person, relying on Hegel's idea of alienation, we argue that objectification, and in particular objectification of various features of the digital environment, may have important system benefits. We present an extended critique of Radin's analysis, basing the critique in part on Gadamer's argument that meaning and application are interrelated and that meaning changes with application. Central to this interplay is the speculative form of analysis that seeks to fix meaning, contrasted with metaphorical thought that seeks to undermine some fixed meanings and create new meanings through interpretation. The result is that speculative and metaphorical forms are conjoined in an interactive process through which new adaptations emerge. Taking this critique an additional step, we use examples from contemporary intellectual property law discourse to demonstrate how an interactive approach, grounded in metaphor, can yield important insights

Observations of composition from Pioneer Venus

Long latitude distributions of atmospheric neutral hydrogen were derived at Venus for the period 1979 to 1980. In-situ measurements of H+, O+, O, and CO2 obtained from the ion and neutral mass spectrometers on the Pioneer Venus orbiter are combined with the appropriate chemical equilibrium relationship to determine the abundance of neutral hydrogen which is very difficult to measure directly. The measurements are all obtained below 165 km on the nightside and below 200 km on the dayside, based on evidence for chemical equilibrium prevailing up to those altitudes. During the period examined nearly three complete diurnal cycles were available and a comparison of the year-to-year variation in hydrogen content is made across the dawn region where the distributions of light gases are most pronounced. The dawn bulge in H (and also in He) which was reported from the first diurnal cycle by Brinton et al. is found to persist. Superimposed upon the diurnal variation are strong day-to-day variations in which n(H) changes by as much as a factor of five. Such variations are linked to pronounced changes in the ion and neutral composition which sometimes occur in association with solar wind disturbances passing the planet. The interaction of the solar wind and the planetary environment somehow results in large changes in the relative abundances and scale heights of the ion and neutral species, thus modifying the derived values of n(H). These variations in the ion distributions are not surprising owing to the strong dependence of the nightside ionization upon convection from the dayside and associated sensitivity of this convection to changes in solar wind pressure and interplanetary magnetic field variations. The variation exhibited by the neutrals, however, appears to require some other explanation owing to the limited momemtum transfer between the ions and neturals. Allowing for these short term perturbations, there appears to be no clear evidence for interannual variation in n(H) during the period examined, apparently consistent with the very small change in solar EUV flux over the same interval