Rocket nozzle thermal shock tests in an arc heater facility

A rocket motor nozzle thermal structural test technique that utilizes arc heated nitrogen to simulate a motor burn was developed. The technique was used to test four heavily instrumented full-scale Star 48 rocket motor 2D carbon/carbon segments at conditions simulating the predicted thermal-structural environment. All four nozzles survived the tests without catastrophic or other structural failures. The test technique demonstrated promise as a low cost, controllable alternative to rocket motor firing. The technique includes the capability of rapid termination in the event of failure, allowing post-test analysis

Short-Term Load Forecasting of Natural Gas with Deep Neural Network Regression

Deep neural networks are proposed for short-term natural gas load forecasting. Deep learning has proven to be a powerful tool for many classification problems seeing significant use in machine learning fields such as image recognition and speech processing. We provide an overview of natural gas forecasting. Next, the deep learning method, contrastive divergence is explained. We compare our proposed deep neural network method to a linear regression model and a traditional artificial neural network on 62 operating areas, each of which has at least 10 years of data. The proposed deep network outperforms traditional artificial neural networks by 9.83% weighted mean absolute percent error (WMAPE)

Sensitivity of LDEF foil analyses using ultra-low background germanium vs. large NaI(Tl) multidimensional spectrometers

Cobalt foils and stainless steel samples were analyzed for induced Co-60 activity with both an ultra-low background germanium gamma-ray spectrometer and with a large NaI(Tl) multidimensional spectrometer, both of which use electronic anticoincidence shielding to reduce background counts resulting from cosmic rays. Aluminum samples were analyzed for Na-22. The results, in addition to the relative sensitivities and precisions afforded by the two methods, are presented

Comments on: AASHO Interim Guide for the Design of Rigid Pavement Structures (AASHO Committee on Design, February, 1962)

We have reviewed the AASHO Interim Guide for the Design of Rigid Pavement Structures, and Messrs. Havens and Hughes of our staff have prepared comments on the guide. These comments do not deal entirely with the rigid pavement guide, but rather compare some of the design concepts from the Flexible Pavement Interim Guide

Forecasting Design Day Demand Using Extremal Quantile Regression

Extreme events occur rarely, making them difficult to predict. Extreme cold events strain natural gas systems to their limits. Natural gas distribution companies need to be prepared to satisfy demand on any given day that is at or warmer than an extreme cold threshold. The hypothetical day with temperature at this threshold is called the Design Day. To guarantee Design Day demand is satisfied, distribution companies need to determine the demand that is unlikely to be exceeded on the Design Day. We approach determining this demand as an extremal quantile regression problem. We review current methods for extremal quantile regression. We implement a quantile forecast to estimate the demand that has a minimal chance of being exceeded on the design day. We show extremal quantile regression to be more reliable than direct quantile estimation. We discuss the difficult task of evaluating a probabilistic forecast on rare events. Probabilistic forecasting is a quickly growing research topic in the field of energy forecasting. Our paper contributes to this field in three ways. First, we forecast quantiles during extreme cold events where data is sparse. Second, we forecast extremely high quantiles that have a very low probability of being exceeded. Finally, we provide a real world scenario on which to apply these techniques

Recent Decisions

Comments on recent decisions by Ronald Rejent, James G. McGoldrick, James H. Neu, William J. Syring, Anthony M. Bernard, Joseph T. Pawlowski, and Robert K. Rodibaugh

RISK-RETURN ANALYSIS OF INCORPORATING ANNUAL LEGUMES AND LAMB GRAZING WITH DRYLAND CROP ROTATIONS

Profitability and risk, 1988-2001, are examined for lamb-grazed field pea as a fallow alternative with wheat, or an extended wheat-sunflower-millet rotation. Switching from conventional wheat-fallow to an extended rotation with grazed-peas increases profitability (2.3% to 7.3%), and reduces risk (below 0% target in only 2 versus 7 of 14 years).Crop Production/Industries,

Economic or amenity driven migration? A cluster-based analysis of county migration in the American southwest: Working paper series--08-01

This paper initially analyzes the determinants of net domestic migration which occurred from 1995 to 2000 at the county level in the 4-Corners Region of the U.S. (Arizona, Colorado, New Mexico and Utah.) Regression techniques were used to explain approximately 70 percent of the variation in net migration rates within the region for counties whose populations exceeded 10,000 persons at the beginning of the period. The results of the study suggest net migration flows in the region are a dual function of both economic and non-economic characteristics existing within each county. The analysis is extended through the use of additional multivariate techniques in order to group the counties into clusters that reflect natural groupings based on a similar profile of variables used in the analysis. Migration activity differed statistically from cluster to cluster based upon variations in the predictor variables used in the analysis. Further research is suggested in order to extend these results to the broader economy

Assessing domestic migration at the county level in the 4-corners region: Working paper series--07-06

This paper analyzes net domestic migration which occurred between 1995 and 2000 at the county level for the 4-Corners Region (Arizona, Colorado, New Mexico, and Utah.) Regression techniques were used to explain approximately 70 percent of the variation in net migration rates within the region for all counties whose populations exceeded 10,000 persons at the beginning of the period. The results of the study suggest net migration rates in the region are a function of both economic and non-economic characteristics existing within each county. Initially, a number of amenity-related, recreation and socio-demographic variables were considered along with traditional economic indicators; however, only a few of the traditional variables were correlated with migration activity to and from this region. Further research is needed in order to explain the differences in migration rates for these locations compared with results discovered in other regions