Compactness and related concepts

M.S.Robert H. Kasrie

Modification of air flows within an industrial carcass chiller using delta wing vortex generators

The chilling of carcasses after slaughter has a considerable bearing on process costs and quality of the meat. Uniform air distribution is essential for the optimal operation of carcass chillers, yet many existing chillers have highly variable and ineffective air flow. This directly affects the uniformity of evaporative weight loss and carcass cooling rates within the chiller. Delta plan aerofoils are known to convert a unidirectional air stream, progressively into a rotational and then turbulent multidirectional fragments of moving air. The aim of this research was to evaluate the use of delta wings to improve air flows inside a venison carcass chiller of typical design used in the New Zealand meat industry. Air flow patterns within the chiller were characterised by measuring mean air speeds with a hot-wire anemometer over 61 grid points at 4 levels in height. Air speeds were found to be highly time-variable so the mean, standard deviation and range of 60 one second air speed measurements were used to represent the air flow at each point on the grid. The measurement of air velocity (speed and direction) using three othoganally mounted propeller anemometers had limited success, as air speeds within the chiller were often below the threshold of the anemometer. Measurements before the installation of the delta wings indicated that a poor air flow distribution existed within the chiller as the majority of air was found to circulate around the walls and floor, producing near stagnant conditions between the carcasses. Delta wings were constructed in two sizes from thin aluminium sheets. Wings were installed into the chiller by suspending them from the ceiling within the evaporator fan delivery air stream. Two wing configurations were trialed: The first wing configuration utilised 3 large delta wings mounted in front of the evaporator fans followed by a row of 6 small wings then a row of 7 small wings (3,6,7). The second delta wing configuration utilised a row of 6 large wings closest to the evaporator fans followed by a row of 9 small wings then a row of 13 small wings (6,9,13). The second delta wing configuration showed superior performance over the first. In comparison to the unmodified chiller without wings, the mean air speeds in the critical region amongst the carcasses increased from 0.4 m/s to 0.6 m/s; the standard deviation of mean air speeds decreased from 0.33 m/s to 0.22 m/s and the percentage of mean air speeds between half and twice the mean increased from 84% to 95%. The second configuration of delta wings also produced a 14% increase in the mean air turbulence intensity (measure of the time-variability in air speed) and reduced the variability of evaporative weight loss within the chiller. Overall, the delta wings were found to be an economic way to improve the performance of a chiller by providing a more uniform and effective air distribution without increasing fan power. This can result in a reduction in chilling times and less potential for weight loss. Their use in both new and existing chillers is recommended

Pragmatic quality metrics for evolutionary software development models

Due to the large number of product, project, and people parameters which impact large custom software development efforts, measurement of software product quality is a complex undertaking. Furthermore, the absolute perspective from which quality is measured (customer satisfaction) is intangible. While we probably can't say what the absolute quality of a software product is, we can determine the relative quality, the adequacy of this quality with respect to pragmatic considerations, and identify good and bad trends during development. While no two software engineers will ever agree on an optimum definition of software quality, they will agree that the most important perspective of software quality is its ease of change. We can call this flexibility, adaptability, or some other vague term, but the critical characteristic of software is that it is soft. The easier the product is to modify, the easier it is to achieve any other software quality perspective. This paper presents objective quality metrics derived from consistent lifecycle perspectives of rework which, when used in concert with an evolutionary development approach, can provide useful insight to produce better quality per unit cost/schedule or to achieve adequate quality more efficiently. The usefulness of these metrics is evaluated by applying them to a large, real world, Ada project

An Economic Analysis of the Potential for Coercion in Consent Solicitations for Bonds

This Article examines why issuers frequently cannot present bondholders with an offer that draws on collective action problems to force the acceptance of the offer by the bondholders. The analysis is restricted to publicly offered bonds. For a number of reasons, privately placed debt presents fewer opportunities for coercion. A prior business relationship among various purchasers, which facilitates cooperation, may be more likely with respect to privately placed debt. Privately placed debt often has more significant protection for the bondholders than public debt with the same level of seniorit

The Business Lawyer as Terrorist Transaction Cost Engineer

Lawyers have garnered a reputation for being unreasonable and excessively contentious. This popular sentiment is embedded in our culture. If lawyers cannot change that perception, a second-best outcome (from the perspective of lawyers) would be the formation of an understanding that there is a reason why they appear to act unreasonably, that it can be desirable for lawyers to act in a way that initially appears to be unreasonable. This Article attempts to build a basis for that understanding in the context of lawyers participating in large commercial transactions

Unicellular algal growth: A biomechanical approach to cell wall dynamics

We present a model for unicellular algal growth as motivated by several experiments implicating the importance of calcium ions and ``loosening'' enzymes in morphogenesis. A growing cell at rest in a diffusive calcium solution is viewed as an elastic shell on short timescales. For a given turgor pressure, we calculate the stressed shapes of the wall elements whose elastic properties are determined by Young's modulus and the thickness of the wall. The local enzyme concentration then determines the rate at which the unstressed shape of a wall element relaxes toward its stressed shape. The local wall thickness is calculated from the calcium-mediated addition of material and thinning due to elongation. We use this model to calculate growth rates for small perturbations to a circular cell. We find an instability related to modulations of the wall thickness, leading to growth rates which peak at a finite wave number.Comment: 5 pages, 2 embedded figure

NASA's Advanced solid rocket motor

The Advanced Solid Rocket Motor (ASRM) will not only bring increased safety, reliability and performance for the Space Shuttle Booster, it will enhance overall Shuttle safety by effectively eliminating 174 failure points in the Space Shuttle Main Engine throttling system and by reducing the exposure time to aborts due to main engine loss or shutdown. In some missions, the vulnerability time to Return-to-Launch Site aborts is halved. The ASRM uses case joints which will close or remain static under the effects of motor ignition and pressurization. The case itself is constructed of the weldable steel alloy HP 9-4-0.30, having very high strength and with superior fracture toughness and stress corrosion resistance. The internal insulation is strip-wound and is free of asbestos. The nozzle employs light weight ablative parts and is some 5,000 pounds lighter than the Shuttle motor used to date. The payload performance of the ASRM-powered Shuttle is 12,000 pounds higher than that provided by the present motor. This is of particular benefit for payloads delivered to higher inclinations and/or altitudes. The ASRM facility uses state-of-the-art manufacturing techniques, including continuous propellant mixing and direct casting

An economic evaluation of liquid manure disposal from confinement finishing hogs

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THE ECOLOGICAL CONSEQUENCES OF HABITAT AND MICROHABITAT USE IN LIZARDS:: A REVIEW

We review the ecological consequences of habitat and microhabitat use in lizards. Different habitats have different biotic and abiotic properties and thus are likely to have different consequences for the lizards that occur in them. Individual performance and life histories are influenced by habitat use, particularly when habitats differ in thermal characteristics that may influence physiological processes or constrain activity. We know relatively little about how the effects of habitat use on individual performance translate into population dynamics. We do know that the ability of lizards to use particular habitats can influence the persistence of populations in the face of habitat changes. Community-level processes (e.g., competition) and community structure (e.g., diversity) can be influenced by habitat use in lizards, often by habitat use facilitating co-existence of two or more potentially competing species. We know relatively little about how other community processes, such as predation and parasitism, are influenced by habitat use