High pressure Hugoniot measurements using Mach waves

Traditionally, most dynamic shock compression experiments are conducted using a plane one-dimensional wave of uniaxial strain. In this case, the evaluation of the equation of state is simplified due to the geometry, but the amplitude of the induced shock wave is limited by the magnitude of the input load. In an effort to dramatically increase the range of pressures that can be accessed by traditional loading methods, a composite target assembly is examined. The target consists of two concentric cylinders aligned with the axial direction parallel to the loading. The target is designed such that on initial loading, the outer cylinder will have a higher shock velocity than the inner material of interest. Conically converging shocks will be generated at the interface between the two materials due to the impedance mismatch. Upon convergence, an irregular reflection occurs and the conical analog of a Mach reflection develops. The Mach reflection will grow until it reaches a steady state, at which point the wave configuration becomes self similar. The resulting high pressure Hugoniot state can then be measured using velocity interferometry and impedance matching. The technique is demonstrated using a planar mechanical impact generated by a powder gun to study the shock response of copper. Two systems are examined which utilize either a low impedance (6061-T6 aluminum) or a high impedance (molybdenum) outer cylinder. A multipoint VISAR experiment will be presented to validate the technique, and will be compared to numerical simulations. The feasibility of measuring an entire Hugoniot curve using full field velocity interferometry (ORVIS) will also be discussed

Remotely piloted LTA vehicle for surveillance

Various aspects of a remotely piloted mini-LTA vehicle for surveillance, monitoring and measurement for civilian and military applications are considered. Applications, operations and economics are discussed

Study of low acceleration space transportation systems. Volume I - Summary Phase II STUDY report

Technical feasibility of electric-nuclear propulsion system for manned Mars missio

Investigation of integrating sphere measurement parameters

Directional and bidirectional reflectance of MgO sphere wall coatings, and directional characteristics of photomultiplier tub

Determination of two-stroke engine exhaust noise by the method of characteristics

A computational technique was developed for the method of characteristics solution of a one-dimensional flow in a duct as applied to the wave action in an engine exhaust system. By using the method, it was possible to compute the unsteady flow in both straight pipe and tuned expansion chamber exhaust systems as matched to the flow from the cylinder of a small two-stroke engine. The radiated exhaust noise was then determined by assuming monopole radiation from the tailpipe outlet. Very good agreement with experiment on an operation engine was achieved in the calculation of both the third octave radiated noise and the associated pressure cycles at several locations in the different exhaust systems. Of particular interest is the significance of nonlinear behavior which results in wave steepening and shock wave formation. The method computes the precise paths on the x-t plane of a finite number of C(sub +), C(sub -) and P characteristics, thereby obtaining high accuracy in determining the tailpipe outlet velocity and the radiated noise

Income Inequality over the Later-Life Course: A Comparative Analysis of Seven OECD Countries

This paper examines income inequality over stages of the later-life course (age 45 and older) and systems that can be used to mitigate this inequality. Two hypotheses are tested: (i) Levels of income inequality decline during old age because public benefits are more equally distributed than work income; (ii) Because of the progressive nature of government benefits, countries with stronger public income security programs are better able to reduce income inequalities during old age. The analysis is performed by comparing age groups within seven OECD countries (Canada, Germany, the Netherlands, Norway, Sweden, the United Kingdom, and the United States) using Luxembourg Income Study data. Both hypotheses are supported. Several conclusions are drawn from the findings.retirement, income dynamics, comparative analysis, public pensions

Microwave backscattering theory and active remote sensing of the ocean surface

The status is reviewed of electromagnetic scattering theory relative to the interpretation of microwave remote sensing data acquired from spaceborne platforms over the ocean surface. Particular emphasis is given to the assumptions which are either implicit or explicit in the theory. The multiple scale scattering theory developed during this investigation is extended to non-Gaussian surface statistics. It is shown that the important statistic for the case is the probability density function of the small scale heights conditioned on the large scale slopes; this dependence may explain the anisotropic scattering measurements recently obtained with the AAFE Radscat. It is noted that present surface measurements are inadequate to verify or reject the existing scattering theories. Surface measurements are recommended for qualifying sensor data from radar altimeters and scatterometers. Additional scattering investigations are suggested for imaging type radars employing synthetically generated apertures

Age-specific Income Inequality and Life Expectancy: New Evidence

Objectives -- The study has two primary goals. First, to test the hypothesis that higher levels of income inequality are related to lower levels of population health with updated data from around year 2000. Second, to examine the inequality-health relationship across the life course with particular focus on old age when income distributions often shift dramatically. Design -- Correlation techniques were used to assess the relationship between income inequality (Gini ratio) at ages 0+, 25+, 65+, 75+, and 85+ and life expectancy at corresponding ages (0, 25, 65, 75, 85) by sex, before and after adjusting for average population income. Analyses were conducted on two sets of data: 18 wealthy countries and 28 wealthy and non-wealthy countries. Data sources -- International cross-sectional data on income and life expectancy from about year 2000 were derived from the Luxembourg Income Study and the United Nations Demographic Yearbook respectively. Results -- Among wealthy countries the negative effect of income inequality on life expectancy at birth becomes insignificant after controlling for average absolute income: the correlation coefficient changes from -0.603 to -0.207 for men and -0.605 to 0.024 for women. A similar pattern is observed at age 25. By contrast, the effect becomes increasingly positive and significant across old age, notably for males, regardless of adjustments for average population income or countries of observation. Conclusions -- These updated results do not support the inequality-health hypothesis. The relationship between income inequality and life expectancy at earlier ages in wealthy countries can be explained by the confounding effect of average absolute income. In old age the data are entirely contrary to the hypothesis. More research is needed to understand the mechanisms that facilitate the increasing positive effect of income inequality on life expectancy in late life.Cross-national; Income Inequality; Population Health; Life Expectancy; Age