A Cavitation Susceptability Meter with Optical Cavitation Monitoring-Part One: Design Concepts

This work is concerned with the design of a Cavitation Susceptibility Meter based on the use of a venturi tube for the measurement of the active cavitation nuclei concentration in water samples as a function of the applied tension. The operation of the Cavitation Susceptibility Meter is analyzed and the main considerations leading to the proposed design are illustrated and critically discussed. The results of this analysis indicate that the operational range is mainly limited by nuclei interference, flow separation and saturation (choking), and suggest to develop a Cavitation Susceptibility Meter where; (1) the flow possesses a laminar potential core throughout the venturi throat section in all operational conditions; (b) the pressure at the venturi throat is determined from the upstream pressure and the local flow velocity; (c) the detection of cavitation and the measurement of the flow velocity are carried out optically by means of a Laser Doppler Velocimeter; (d) a custom-made electronic Signal Processor incorporating a frequency counter is used for real time data generation and temporary storage; (e) a computerized system performs the final acquisition and reduction of the data

Separation and Surface Nuclei Effects in a Cavitation Susceptibility Meter

This work is concerned with the effects of flow separation and surface nuclei on the operation of a fixed geometry Cavitation Susceptibility Meter (CSM) with laminar flow. Cavitation is induced under controlled conditions at the throat of a glass venturi tube for the measurement of the active nuclei concentration in water samples as a function of the applied tension. Both cavitation and flow velocity are monitored optically by a Laser Doppler Velocimeter. The throat pressure is determined indirectly from the upstream pressure and the local flow velocity. The results show that laminar flow separation and surface nuclei effects are the most stringent operational limitations. Separation in the diffuser increases the minimum attainable throat pressure above the susceptibility of most cavitation nuclei commonly found in technical waters. Surface nuclei can generate extensive sheet or spot cavitation at relatively high tensions even on optically finished glass surfaces. These phenomena are difficult to eliminate and bring therefore into question the practical utility of CSM's with laminar flow and fixed geometry for the measurement of the dependence of the cavitating nuclei concentration over wide ranges of the applied tension, as required for cavitation studies

A Cavitation Susceptibility Meter with Optical Cavitation Monitoring -- Part Two: Experimental Apparatus and Results

This work in concerned with the development and operation of a Cavitation Susceptibility Meter based on the use of a venturi tube for the measurement of the active cavitation nuclei concentration in water samples as a function of the applied tension. The pressure at the venturi throat is determined from the upstream pressure and the local flow velocity without corrections for viscous effects because the flow possesses a laminar potential core in all operational conditions. The detection of cavitation and the measurement of the flow velocity are carried out optically by means of a Laser Doppler Velocimeter. A custom-made electronic Signal Processor is used for real time data generation and temporary storage and a computerized system for final data acquisition and reduction. The implementation of the whole system is described and the results of the application of the Cavitation Susceptibility Meter to the measurement of the water quality of tap water samples are presented and critically discussed with reference to the current state of knowledge on cavitation inception

Assessing the Effects of Military Expenditure on Growth

Military spending is an expenditure by governments that has influence beyond the resources it takes up, especially when it leads to or facilitates conflicts. This chapter provides an overview of the issues involved in analysing the effects of military spending on growth. It considers the alternative general economic theories that inform the development of models to undertake empirical analyses, and estimation issues in undertaking those analyses. The Feder-Ram model, the modified Solow and the endogenous growth models, are discussed in detail, before being estimated to illustrate the issues involved in estimating the models and to compare their performance.Military spending; growth; panels spending,semi-parametric estimation

Corruption, Military Spending and Growth

This paper considers the complementary effect of corruption and military spending on economic growth, analyzing both the direct impact of public spending and effect of allocating resources between categories of public spending within the framework of an endogenous growth model. The non-linearities that emerge from are the result of the links between the components of public spending, corruption and economic growth. The main findings of the empirical analysis confirm the expectation that corruption and military burden lower the growth rate of GDP per capita. They also suggest that when the the complementarity effect between military spending and corruption is omitted, as in most studies, the impact of military burden on economic performance is underestimated.corruption, military spending, development economics

Optimal Military Spending in the US: A Time Series Analysis

This paper extends previous work on the optimal size of government spend- ing by including nested functional decompositions of military spending into consumption and investment. Post World War II US data are then used to estimate nested non-linear growth models using semiparametric methods. As expected, investment in military and non-military expenditure are both found to be productive expenditures. Moreover there is little evidence to suggest that current military spending is having a negative impact on economic growth in the US, while civilian consumption only tends to have only a weak impact. This does not imply that society will necessarily bene?t from a reallocation of more spending to the military sector, nor that it is the best way to achieve economic growth. It does suggest that the US economy is not necessarily being hindered by its current military burden.Economic growth; productive state spending; military spending,semi-parametric estimation

Order parameter fluctuations and thermodynamic phase transitions in finite spin systems and fragmenting nuclei

We show that in small and low density systems described by a lattice gas model with fixed number of particles the location of a thermodynamic phase transition can be detected by means of the distribution of the fluctuations related to an order parameter which is chosen to be the size of the largest fragment. We show the correlation between the size of the system and the observed order of the transition. We discuss the implications of this correlation on the analysis of experimental fragmentation data.Comment: 9 pages including 5 figures. Final version to appear in PL

Protecting buyers from fine print

Buyers typically do not read the …ne print in contracts, providing an incentive for a monopolist to draft terms which are unfavorable to buyers. We model this problem, proving that trade must then be inefficient. We show that regulation which mandates efficient terms raises welfare. More interestingly, regulations which prohibit the least efficient terms may reduce welfare by inducing the monopolist not to other favorable terms. We extend these results to markets in which some buyers are naive, showing that prohibiting the least efficient terms may also harm the naive buyers

Color in context: psychological context moderates the influence of red on approach- and avoidance-motivated behavior.

A basic premise of the recently proffered color-in-context model is that the influence of color on psychological functioning varies as a function of the psychological context in which color is perceived. Some research has examined the appetitive and aversive implications of viewing the color red in romance- and achievement-relevant contexts, respectively, but in all existing empirical work approach and avoidance behavior has been studied in separate tasks and separate experiments. Research is needed to directly test whether red influences the same behavior differently depending entirely on psychological context. The present experiment was designed to put this premise to direct test in romance- and achievement-relevant contexts within the same experimental paradigm involving walking behavior. Our results revealed that exposure to red (but not blue) indeed has differential implications for walking behavior as a function of the context in which the color is perceived. Red increased the speed with which participants walked to an ostensible interview about dating (a romance-relevant context), but decreased the speed with which they walked to an ostensible interview about intelligence (an achievement-relevant context). These results are the first direct evidence that the influence of red on psychological functioning in humans varies by psychological context. Our findings contribute to both the literature on color psychology and the broader, emerging literature on the influence of context on basic psychological processes