Performance prediction of point-based three-dimensional volumetric measurement systems

Point-based three-dimensional volumetric measurement systems are defined as multi-view vision systems which reconstruct a three-dimensional scene by first identifying key points on the views and then performing the reconstruction. Examples of these are defocusing digital particle image velocimetry (DDPIV) (Pereira et al 2000 Exp. Fluids 29 S78–84) and 3D particle tracking velocimetry (3DPTV) (Papantoniou and Maas 1990 5th Int. Symp. on the Application of Laser Techniques in Fluid Mechanics) which reconstruct clouds of flow tracers in order to estimate flow velocities. The reconstruction algorithms in these systems are variations of an epipolar line search. This paper presents a generalized error analysis of such methods, both in reconstruction precision (error in the reconstructed scene) and reconstruction quality (number of ambiguities or 'ghosts' produced)

Zinc-oxygen primary cell yields high energy density

Zinc-oxygen primary cell yields high energy density for battery used as an auxiliary power source in space vehicle systems. Maximum reliability and minimum battery weight is achieved by using a stacking configuration of 23 series-connected modules with 6 parallel-connected cells per module

GRID PRICING: VALUING CATTLE QUALITY INFORMATION

Grid pricing is increasingly prominent in cattle markets. This study compares selling 11,703 head of fed cattle using grid, live, and dressed weight pricing. Cattle sold on a grid had price variability twice that of live or dressed. Average pricing inefficiency by not selling cattle on a grid exceeded $30/head.Demand and Price Analysis, Livestock Production/Industries,

Simulating a White Dwarf-dominated Galactic Halo

Observational evidence has suggested the possibility of a Galactic halo which is dominated by white dwarfs (WDs). While debate continues concerning the interpretation of this evidence, it is clear that an initial mass function (IMF) biased heavily toward WD precursors (1 < m/Msol < 8), at least in the early Universe, would be necessary in generating such a halo. Within the framework of homogeneous, closed-box models of Galaxy formation, such biased IMFs lead to an unavoidable overproduction of carbon and nitrogen relative to oxygen (as measured against the abundance patterns in the oldest stars of the Milky Way). Using a three-dimensional Tree N-body smoothed particle hydrodynamics code, we study the dynamics and chemical evolution of a galaxy with different IMFs. Both invariant and metallicity-dependent IMFs are considered. Our variable IMF model invokes a WD-precursor-dominated IMF for metallicities less than 5% solar (primarily the Galactic halo), and the canonical Salpeter IMF otherwise (primarily the disk). Halo WD density distributions and C,N/O abundance patterns are presented. While Galactic haloes comprised of ~5% (by mass) of WDs are not supported by our simulations, mass fractions of ~1-2% cannot be ruled out. This conclusion is consistent with the present-day observational constraints.Comment: accepted for publication in MNRA

Compressible Flows in Fluidic Oscillators

We present qualitative observations on the internal flow characteristics of fluidic oscillator geometries commonly referred to as sweeping jets in active flow control applications. This is part of the fluid dynamics videos.Comment: Videos include

Apollo 17 EVA-1 and EVA-2 Task Decomposition: Planning for Artemis and Future Mars Missions

A decomposition of the Apollo 17 mission extravehicular activities (EVA) tasks can be used to prepare for Artemis and future Mars missions. A categorized minute by minute breakdown of the astronauts activites could be used to plan future EVAs and determine which scientific tasks or equipment may be prioritized. This is especially relevant in this critical stage for the upcoming Atemis missions and science activity planning. The infographics generated from the decomposition provide a higher level view of actual EVAs and could aid in making future EVAs more efficient and successful

Magnitude bias of microlensed sources towards the Large Magellanic Cloud

There are lines of evidence suggesting that some of the observed microlensing events in the direction of the Large Magellanic Cloud (LMC) are caused by ordinary star lenses as opposed to dark Machos in the Galactic halo. Efficient lensing by ordinary stars generally requires the presence of one or more additional concentrations of stars along the line of sight to the LMC disk. If such a population behind the LMC disk exists, then the source stars (for lensing by LMC disk objects) will be drawn preferentially from the background population and will show systematic differences from LMC field stars. One such difference is that the (lensed) source stars will be farther away than the average LMC field stars, and this should be reflected in their apparent baseline magnitudes. We focus on red clump stars: these should appear in the color-magnitude diagram at a few tenths of a magnitude fainter than the field red clump. Suggestively, one of the two near-clump confirmed events, MACHO-LMC-1, is a few tenths of magnitude fainter than the clump.Comment: To appear in ApJ Letters. Shortened to match the accepted version, 8 pages plus 1 ps figur

Electrochemical energy storage subsystems study, volume 1

The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models define baseline designs and costs. The major design and performance parameters are each varied to determine their influence on LCC around the baseline values

Analysis of a Hubble Space Telescope Search for Red Dwarfs: Limits on Baryonic Matter in the Galactic Halo

We re-examine a deep {\it Hubble Space Telescope} pencil-beam search for red dwarfs, stars just massive enough to burn Hydrogen. The authors of this search (Bahcall, Flynn, Gould \& Kirhakos 1994) found that red dwarfs make up less than 6\% of the galactic halo. First, we extrapolate this result to include brown dwarfs, stars not quite massive enough to burn hydrogen; we assume a $1/{\cal M}$ mass function. Then the total mass of red dwarfs and brown dwarfs is $\leq$18\% of the halo. This result is consistent with microlensing results assuming a popular halo model. However, using new stellar models and parallax observations of low mass, low metallicity stars, we obtain much tighter bounds on low mass stars. We find the halo red dwarf density to be $<1\%$ of the halo, while our best estimate of this value is 0.14-0.37\%. Thus our estimate of the halo mass density of red dwarfs drops to 16-40 times less than the reported result of Bahcall et al (1994). For a $1/{\cal M}$ mass function, this suggests a total density of red dwarfs and brown dwarfs of $\sim$0.25-0.67\% of the halo, \ie , (0.9-2.5)\times 10^9\msun out to 50 kpc. Such a low result would conflict with microlensing estimates by the \macho\ group (Alcock \etal 1995a,b).Comment: 13 pages, 2 figures. Figure one only available via fax or snail-mail To be published in ApJL. fig. 2 now available in postscript. Some minor changes in dealing with disk forground. Some cosmetic changes. Updated reference

Responsibility without legal authority? Tackling alcohol-related health harms through licensing and planning policy in local government.

BACKGROUND: The power to influence many social determinants of health lies within local government sectors that are outside public health's traditional remit. We analyse the challenges of achieving health gains through local government alcohol control policies, where legal and professional practice frameworks appear to conflict with public health action. METHODS: Current legislation governing local alcohol control in England and Wales is reviewed and analysed for barriers and opportunities to implement effective population-level health interventions. Case studies of local government alcohol control practices are described. RESULTS: Addressing alcohol-related health harms is constrained by the absence of a specific legal health licensing objective and differences between public health and legal assessments of the relevance of health evidence to a specific place. Local governments can, however, implement health-relevant policies by developing local evidence for alcohol-related health harms; addressing cumulative impact in licensing policy statements and through other non-legislative approaches such as health and non-health sector partnerships. Innovative local initiatives-for example, minimum unit pricing licensing conditions-can serve as test cases for wider national implementation. CONCLUSIONS: By combining the powers available to the many local government sectors involved in alcohol control, alcohol-related health and social harms can be tackled through existing local mechanisms