Temperature and pressure measurement techniques for an advanced turbine test facility

A high pressure, high-temperature turbine test facility constructed for use in turbine cooling research is described. Several recently developed temperature and pressure measuring techniques are used in this facility. The measurement techniques, their status, previous applications and some results are discussed. Noncontact surface temperature measurements are made by optical methods. Radiation pyrometry principles combined with photoelectric scanning are used for rotating components and infrared photography for stationary components. Contact (direct) temperature and pressure measurements on rotating components are expected to be handled with an 80 channel rotary data package which mounts on and rotates with the turbine shaft at speeds up to 17,500 rpm. The data channels are time-division multiplexed and converted to digital words in the data package. A rotary transformer couples power and digital data to and from the shaft

Finite range corrections near a Feshbach resonance and their role in the Efimov effect

We have measured the binding energy of $^7$Li Feshbach molecules deep into the non-universal regime by associating free atoms in a Bose-Einstein condensate by modulating the magnetic field. We extract the scattering length from these measurements, correcting for non-universal short-range effects using several different methods. We find that field-dependent effective range corrections agree well with the data. With this more precise determination of the scattering length vs. field we reanalyze our previous data on the location of atom loss features produced by the Efimov effect \cite{PollackSci09} and investigate effective range corrections to universal theory.Comment: Accepted for publication in Phys. Rev.

Demonstration of the Zero-Crossing Phasemeter with a LISA Test-bed Interferometer

The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black hole binaries. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. We present current results of a test-bed interferometer designed to produce an optical LISA-like fringe signal previously discussed in the literature.Comment: find minor corrections in the CQG versio

A Demonstration of LISA Laser Communication

Over the past few years questions have been raised concerning the use of laser communications links between sciencecraft to transmit phase information crucial to the reduction of laser frequency noise in the LISA science measurement. The concern is that applying medium frequency phase modulations to the laser carrier could compromise the phase stability of the LISA fringe signal. We have modified the table-top interferometer presented in a previous article by applying phase modulations to the laser beams in order to evaluate the effects of such modulations on the LISA science fringe signal. We have demonstrated that the phase resolution of the science signal is not degraded by the presence of medium frequency phase modulations.Comment: minor corrections found in the CQG versio

Proceedings of the MECA Workshop on The Evoluation of the Martian Atmosphere

Topics addressed include: Mars' volatile budget; climatic implications of martian channels; bulk composition of Mars; accreted water inventory; evolution of CO2; dust storms; nonlinear frost albedo feedback on Mars; martian atmospheric evolution; effects of asteroidal and cometary impacts; and water exchange between the regolith and the atmosphere/cap system over obliquity timescales

Stratospheric aerosol modification by supersonic transport operations with climate implications

The potential effects on stratospheric aerosois of supersonic transport emissions of sulfur dioxide gas and submicron size soot granules are estimated. An interactive particle-gas model of the stratospheric aerosol is used to compute particle changes due to exhaust emissions, and an accurate radiation transport model is used to compute the attendant surface temperature changes. It is shown that a fleet of several hundred supersonic aircraft, operating daily at 20 km, could produce about a 20% increase in the concentration of large particles in the stratosphere. Aerosol increases of this magnitude would reduce the global surface temperature by less than 0.01 K

Extreme tunability of interactions in a 7^7Li Bose-Einstein condensate

We use a Feshbach resonance to tune the scattering length a of a Bose-Einstein condensate of 7Li in the |F = 1, m_F = 1> state. Using the spatial extent of the trapped condensate we extract a over a range spanning 7 decades from small attractive interactions to extremely strong repulsive interactions. The shallow zero-crossing in the wing of the Feshbach resonance enables the determination of a as small as 0.01 Bohr radii. In this regime, evidence of the weak anisotropic magnetic dipole interaction is obtained by comparison with different trap geometries

Regionalisation of Northern Territory land councils

The dispersal of the powers exercised and functions performed by the two major land councils has been a subject of debate and recommendations on a number of occasions since the Aboriginal Land Rights (Northern Territory) Act 1976 came into effect. The Reeves Review of the Act in 1998, and the subsequent Inquiry into that Review by the House of Representatives Standing Committee on Aboriginal and Torres Strait Islander Affairs (HORSCATSIA) this year, have raised the issue to prominence again and ensured that it will be dealt with in the coming round of statutory amendments. This Discussion Paper considers the steps that have been taken towards regionalisation under the current provisions of the Act, and compares models for further regionalisation proposed by David Martin, the two land councils, and HORSCATSIA. These proposals, while more moderate than that of Reeves in that they all presume the continued existence of the Northern and Central Land Councils, differ on a number of points. Regionalisation within, or outside, the existing land council structures, provision for local initiative in seeking devolution, and the role of the Minister, are among the matters at issue in an attempt to secure both increased local or regional autonomy and improved land council efficiency. Funding of regionalised bodies also demands attention, given the criticisms directed at this aspect of the Reeves model. This paper goes on to express concern that regionalisation has been accepted as a selfevidently desirable policy, and that insufficient critical attention has been paid to the advantages expected to flow from its implementation. We begin our critique by distinguishing between ‘administrative’ regionalisation and ‘decision-making’ regionalisation of land council functions and powers. We then separate out the real process of decision-making from the formal act of decision-taking in the scheme of the Act. Most importantly, we point to the already localised character of decisions by traditional owners under the informed consent provisions, and argue that the primary danger posed by regionalisation is that the regional decision-takers will trespass upon the decision-making prerogatives of the traditional owners. While in our view this problem is a threat to the fundamental distribution of authority under the existing Act, and is sufficiently serious to call into question the rationale for moves towards greater regionalisation, the breadth of opinion, including local Aboriginal sentiment, in favour of more localised autonomy, needs to be accommodated. We therefore argue for a number of measures in mitigation. Establishing regional areas of sufficiently large size, each represented by a committee or council of sufficiently small size, and serviced, in the case of internal land council regionalisation, by professional staff employed through the central organisation, are steps intended to protect the informed consent procedures of the Act. Some formal certification witnessing the adequacy of those procedures in each case should also be introduced as part of the conditions attaching to the affixing of the land council common seal to agreements. As only some of these measures are available in the case of independent, or ‘breakaway’, land councils, some caution is due in approving more of these, especially in assessing the spread and depth of popular support

Optical constants of solid methane

Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH4 for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. Preliminary results are presented on the optical constants of solid methane for the 0.4 to 2.6 micrometer region. Deposition onto a substrate at 10 K produces glassy (semi-amorphous) material. Annealing this material at approximately 33 K for approximately 1 hour results in a crystalline material as seen by sharper, more structured bands and negligible background extinction due to scattering. The constant k is reported for both the amorphous and the crystalline (annealed) states. Typical values (at absorption maxima) are in the .001 to .0001 range. Below lambda = 1.1 micrometers the bands are too weak to be detected by transmission through the films less than or equal to 215 micrometers in thickness, employed in the studies to date. Using previously measured values of the real part of the refractive index, n, of liquid methane at 110 K, n is computed for solid methane using the Lorentz-Lorenz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for condensed CH4

Gluing Initial Data Sets for General Relativity

We establish an optimal gluing construction for general relativistic initial data sets. The construction is optimal in two distinct ways. First, it applies to generic initial data sets and the required (generically satisfied) hypotheses are geometrically and physically natural. Secondly, the construction is completely local in the sense that the initial data is left unaltered on the complement of arbitrarily small neighborhoods of the points about which the gluing takes place. Using this construction we establish the existence of cosmological, maximal globally hyperbolic, vacuum space-times with no constant mean curvature spacelike Cauchy surfaces.Comment: Final published version - PRL, 4 page