Computer program for numerical analysis of stiffened shells of revolution

Programs, using Love-Reissner first-order shell theory, can analyze orthotropic thin shells of revolution subjected to unsymmetric distributed loading or concentrated line loads and thermal strains. They can perform stability or vibration analysis of thin shells of revolution subjected to axisymmetric distributed loading or concentrated line loads and thermal strains

Flammability study of materials in oxygen environments

Report presents flame-propagation rates and flammability ratings of 780 specimens of commercially available plastics, elastomers, coatings, fabrics, and other sheet materials. Test results are also given for over 1970 samples of most commonly used electrical harnesses, connectors, and potting compounds

RISK AND STRUCTURAL CHANGE IN AGRICULTURE: HOW INCOME SHOCKS INFLUENCE FARM SIZE

Farm-level Census data and county-level income shock data reveal that past unexpected income shocks affect the rate of change in average farm size. Average farm size increases more quickly in counties experiencing negative income shocks as compared to counties experiencing positive income shocks. This result cannot be explained by perfect-market models, which predict farm size should adjust according to changes in the relative prices of labor and capital. We posit a model wherein cash flows affect liquidity, which in turn affects farm borrowing and capital costs. In the model, farms that do not face liquidity constraints benefit from negative income shocks because they reduce land values, so these farms expand while liquidity-constrained farms contract. Observed farm consolidation patterns and farm exit rates are consistent with a model wherein liquidity constraints affect small farms more than large farms.farm size, farm structure, income shocks, liquidity constraint, risk, Agricultural Finance, Industrial Organization,

Did the Baby Boom Cause the Farm-Size Boom?

Growing farm size has generally been explained by technological advances that have allowed farmers to substitute capital for labor. Another possible factor in explaining recent farm size is the demographic shift: the age distribution of farmers has shifted to the right and older farmers generally operate larger farms than younger farmers. This paper uses data from the 1982, 1987, 1992, 1997, and 2002 Agricultural Censuses to examine the relative importance of the demographic shift versus technological factors in explaining overall farm size growth. Results indicate that farm sizes tend to increase with age and that, holding age constant, the typical farm-size has increased over time for all ages, presumably due to technological change. The age-distribution shift is combined with the age-specific farm-size shift, to provide a preliminary estimate of the effect of the age distribution shift and technological change on average farm size growth.farm structure, demographic shift, age distribution, farm size distribution, Farm Management, Industrial Organization, Labor and Human Capital,

Government Payments and Farmland Concentration

Over the last twenty five years commodity crop farms have steadily declined in number and grown in average size, and production has shifted to larger operations. During the same period, the share of agricultural payments going to large farms has increased, in large part because payments are tied to actual or historical crop production. This study evaluates whether payments from federal farm programs may have contributed to the concentration of farmland. Using zip code-level data constructed from the micro files of the 1987-2002 Agriculture Censuses the study estimates the association between government payments per acre and subsequent growth in weighted median farmland area. A semi-parametric generalized additive model controls for location and initial concentration levels, and narrows comparisons to nearby zip codes with similar average farm sizes. Findings indicate, both with and without spatial controls, that government payments are strongly associated with subsequent concentration growth.Agricultural and Food Policy,

Commodity Payments, Farm Business Survival, and Farm Size Growth

In the last 25 years, U.S. crop farms have steadily declined in number and grown in average size, as production has shifted to larger operations. Larger farms tend to receive more commodity program payments because most payments are tied to a farm’s current or historical production, but whether payments have contributed to farm growth is uncertain. This study uses farm-level data from the census of agriculture to determine whether there is a statistical relationship between farm commodity program payments and greater concentration in production. The analysis indicates that, at the regional level, higher commodity program payments per acre are associated with subsequent farm growth. Also, higher payments per acre are associated with higher rates of farm survival and growth.agricultural payments, farm size, farm survival, concentration, consolidation, government payments, commodity programs., Agribusiness, Agricultural and Food Policy, Community/Rural/Urban Development, Crop Production/Industries, Farm Management,

High-Pressure Oxygen Test Evaluations

The relevance of impact sensitivity testing to the development of the space shuttle main engine is discussed in the light of the special requirements for the engine. The background and history of the evolution of liquid and gaseous oxygen testing techniques and philosophy is discussed also. The parameters critical to reliable testing are treated in considerable detail, and test apparatus and procedures are described and discussed. Materials threshold sensitivity determination procedures are considered and a decision logic diagram for sensitivity threshold determination was plotted. Finally, high-pressure materials sensitivity test data are given for selected metallic and nonmetallic materials

Do Government Payments Influence Farm Business Survival?

Using a unique farm-level panel data set derived from three U.S. Agricultural Censuses, we estimate a Cox proportional hazard model to examine the effect of direct government payments on the survival of farm businesses, paying particular attention to the differential effect of payments across farm size categories. For identification the study exploits variation in payments resulting from historical differences in 'base acreage' in otherwise similar farms. We find an increase in government payments has a small but statistically significant positive effect on the rate of farm survival, and the magnitude of this effect increases with farm size.Agricultural and Food Policy,