Combustion/particle sizing experiments at the Naval Postgraduate School Combustion Research Laboratory

Particle behavior in combustion processes is an active research area at NPS. Currently, four research efforts are being conducted: (1) There is a long standing need to better understand the soot production and combustion processes in gas turbine combustors, both from a concern for improved engine life and to minimize exhaust particulates. Soot emissions are strongly effected by fuel composition and additives; (2) A more recent need for particle sizing/behavior measurements is in the combustor of a solid fuel ramjet which uses a metallized fuel. High speed motion pictures are being used to study rather large burning particles; (3) In solid propellant rocket motors, metals are used to improve specific impulse and/or to provide damping for combustion pressure oscillations. Particle sizing experiments are being conducted using diode arrays to measure the light intensity as a function of scattering angle; (4) Once a good quality hologram is attained, a need exists for obtaining the particle distributions from hologram in a short period of time. A Quantimet 720 Image Analyzer is being used to reconstruct images

Particle sizing in rocket motor studies utilizing hologram image processing

A technique of obtaining particle size information from holograms of combustion products is described. The holograms are obtained with a pulsed ruby laser through windows in a combustion chamber. The reconstruction is done with a krypton laser with the real image being viewed through a microscope. The particle size information is measured with a Quantimet 720 image processing system which can discriminate various features and perform measurements of the portions of interest in the image. Various problems that arise in the technique are discussed, especially those that are a consequence of the speckle due to the diffuse illumination used in the recording process

Consequences of means testing Social Security: evidence from the SSI program

A treatise that draws inferences about the potential behavorial responses to means testing Social Security by examining the effects of the Supplementary Security Income program for the aged on wealth accumulation and employment.Labor supply ; Social security

The Supplemental Security Income Program and Incentives to Take Up Social Security Early Retirement: Empirical Evidence from Matched SIPP and Social..

Features of the Supplemental Security Income (SSI) program and the social security retirement system may interact in a manner that creates incentives for prospective SSI recipients to take social security early retirement (SSER). This paper takes a first close look at this issue. The work disincentives posed by SSI rules and the potential interactions between the SSI and SSER programs are outlined in a basic theoretical framework. The hypotheses that emerge can be tested using public-use microdata linked to Social Security Administration records. We first present evidence supporting the hypothesis that SSI rules induce prospective SSI recipients to substantially reduce work activity (by various measures) prior to age 65. We then present two types of evidence on SSI-SSER interactions. We do not find a simple correspondence between generous SSI benefits and SSER use, which might be an expected indirect SSI-SSER interaction. However, estimates for some specifications for SSER receipt, derived directly from the theoretical interaction between SSER and SSI rules through the household budget constraint, provide evidence of a direct interaction between SSER and SSI, with SSI inducing use of SSER for those individuals for whom the SSI-SSER interaction eliminates the reduction in benefits associated with early receipt of social security benefits.

SSI, Labor Supply, and Migration

The Supplemental Security Income (SSI) program in the United States creates incentives for potential aged recipients to reduce labor supply prior to becoming eligible, and past research finds evidence of such behavior for older men. There may be a migration response to across-state variation in SSI benefits, which is of interest in its own right and can bias estimates of the effects of SSI benefits on labor supply. We fail to find evidence that older individuals migrate in response to SSI benefits, or that the labor supply disincentive effects of SSI are spurious and instead reflect migration behavior.Supplemental Security Income; Migration; Labor supply