Method and means for helium/hydrogen ratio measurement by alpha scattering

An apparatus for determining helium to hydrogen ratios in a gaseous sample is presented. The sample is bombarded with alpha particles created by a self contained radioactive source and scattering products falling within a predetermined forward scattering angular range impact a detector assembly. Two detectors are mounted in tandem, the first completely blocking the second with respect to incident scattering products. Alpha particle/hydrogen or alpha particle/helium collisions are identified by whether scattering product impacts occur simultaneously in both detectors or only in the first detector. Relative magnitudes of the two pulses can be used to further discriminate against other effects such as noise and cosmic ray events

Testing for Hypothetical Bias in Contingent Valuation Using a Latent Choice Multinomial Logit Model

The most persistently troubling empirical result in the contingent valuation method literature is the tendency for hypothetical willingness to pay to overestimate real willingness to pay. We suggest a new approach to test and correct for hypothetical bias using a latent choice multinomial logit (LCMNL) model. To develop this model, we extend Dempster, Laird, and Rubin’s (1977) work on the EM algorithm to the estimation of a multinomial logit model with missing information on categorical membership. Using data on both the quality of water in the Catawba River in North Carolina and the preservation of Saginaw wetlands in Michigan, we find two types of “yes” responders in both data sets. We suggest that one set of yes responses are yea-sayers who suffer from hypothetical bias and answer yes to the hypothetical question but would not pay the bid amount if it were real. The second group does not suffer from hypothetical bias and would pay the bid amount if it were real.C25, P230, Q51

Silicon-on-ceramic process: Silicon sheet growth and device development for the large-area silicon sheet task of the low-cost solar array project

The technical feasibility of producing solar cell quality sheet silicon to meet the DOE 1986 cost goal of 70 cents/watt was investigated. The silicon on ceramic approach is to coat a low cost ceramic substrate with large grain polycrystalline silicon by unidirectional solidification of molten silicon. Results and accomplishments are summarized

Estimating Peak Demand for Beach Parking Spaces

The United States Army Corps of Engineers planning guidance stipulates that in order for local beach communities to qualify for Federal cost share funds for Hurricane and Storm Damage Reduction beach renourishment projects, the community must provide public beach access and parking to satisfy peak demand. This study presents a method for estimating peak demand for beach parking spaces in the presence of parking constraints. A Tobit regression model is developed to estimate the number of parking spaces that would be necessary to meet unconstrained demand on a given percentage of peak demand days. For example, the model can be used to estimate the number of parking spaces that would be adequate to meet peak demand on 90% of peak parking days. The Tobit model provides a promising framework for estimating peak parking demand under constrained parking conditions, a situation that characterizes most beach communities.