Orbit transfer rocket engine technology program. Phase 2: Advanced engine study

In Phase 2 of the Advanced Engine Study, the Failure Modes and Effects Analysis (FMEA) maintenance-driven engine design, preliminary maintenance plan, and concept for space operable disconnects generated in Phase 1 were further developed. Based on the results of the vehicle contractors Orbit Transfer Vehicle (OTV) Concept Definition and System Analysis Phase A studies, minor revisions to the engine design were made. Additional refinements in the engine design were identified through further engine concept studies. These included an updated engine balance incorporating experimental heat transfer data from the Enhanced Heat Load Thrust Chamber Study and a Rao optimum nozzle contour. The preliminary maintenance plan of Phase 1 was further developed through additional studies. These included a compilation of critical component lives and life limiters and a review of the Space Shuttle Main Engine (SSME) operations and maintenance manual in order to begin outlining the overall maintenance procedures for the Orbit Transfer Vehicle Engine and identifying technology requirements for streamlining space-based operations. Phase 2 efforts also provided further definition to the advanced fluid coupling devices including the selection and preliminary design of a preferred concept and a preliminary test plan for its further development

Profit Patterns Across American Agriculture

To remain viable, agriculture in each location must offer returns that are competitive with those from alternative investments and sufficient to cover producers' financial obligations. Economic theory says that rates of return converge over time as resources flow into more-profitable industries and out of less-profitable industries, causing factor price changes. Both traditional growth and trade theories say factor markets will adjust to equalize commodity returns over time. This study examines spatial relationships in agriculture's profitability over time. Results show temporal and spatial convergence of returns consistent with trade and development theories. However, there are profit patterns unique to state/regional agriculture, raising policy implications.convergence, return on assets, "risk of ruin", Agribusiness,

Orbit Transfer Rocket Engine Technology Program: Advanced engine study, task D.1/D.3

Concepts for space maintainability of OTV engines were examined. An engine design was developed which was driven by space maintenance requirements and by a failure mode and effects (FME) analysis. Modularity within the engine was shown to offer cost benefits and improved space maintenance capabilities. Space operable disconnects were conceptualized for both engine change-out and for module replacement. Through FME mitigation the modules were conceptualized to contain the least reliable and most often replaced engine components. A preliminary space maintenance plan was developed around a controls and condition monitoring system using advanced sensors, controls, and condition monitoring concepts. A complete engine layout was prepared satisfying current vehicle requirements and utilizing projected component advanced technologies. A technology plan for developing the required technology was assembled

Hypersonic test facility Patent

Hypersonic test facility for studying ablation in models under high pressure and high temperatur

Fault Localization in Multi-Threaded C Programs using Bounded Model Checking (extended version)

Software debugging is a very time-consuming process, which is even worse for multi-threaded programs, due to the non-deterministic behavior of thread-scheduling algorithms. However, the debugging time may be greatly reduced, if automatic methods are used for localizing faults. In this study, a new method for fault localization, in multi-threaded C programs, is proposed. It transforms a multi-threaded program into a corresponding sequential one and then uses a fault-diagnosis method suitable for this type of program, in order to localize faults. The code transformation is implemented with rules and context switch information from counterexamples, which are typically generated by bounded model checkers. Experimental results show that the proposed method is effective, in such a way that sequential fault-localization methods can be extended to multi-threaded programs.Comment: extended version of paper published at SBESC'1

Agricultural Profits and Farm Household Wealth: A Farm-level Analysis Using Repeated Cross Sections

This study examines the relationship between agricultural profits and farm household wealth across locations and farm sizes in U.S. agriculture. A multiperiod household model is used to develop hypotheses for testing. Results indicate that farmland has out-performed nonfarm investments over the past decade. Thus, households may want to keep their farmland to build wealth, even if it requires them to earn off-farm income. The analysis implies that decision will be made based on farm household wealth factors having little to do with agriculture.farm household, off-farm income, production profits, wealth, Agribusiness, Demand and Price Analysis, Farm Management, Risk and Uncertainty, Q12, Q14,

Off-farm Income and Investments in Farm Assets: A Double Hurdle Approach

The farm household structure is a complex set of inter-relationships between and among a variety of internal and external factors involving consumption, investment, and income-earning activities. In this paper we use ARMS data to explore the contribution of off-farm income to the viability of the farm business. We focus on the link between off-farm income and farm investment and whether off-farm income drives on-farm investment. The results indicate the importance of farm characteristics such as type, size, and location on the probability of investment but lead us to reject the hypothesis that off farm income is driving farm investment. Further research will be needed to further unweave some of the complex relationships involved in the farm household structure. Keywords: Farm investments, off-farm income, double hurdleOff-farm income, farm investment, double hurdle, Agricultural Finance, Financial Economics, D1, J2, Q12,

REGIONAL CHANGES IN THE DISTRIBUTION OF NET VALUE ADDED IN U.S. AGRICULTURE, 1960-2002

This paper examines the effects of structural changes on the distribution of net value added and the difference between net value added and agricultural income over time. We present and discuss the changes in the distribution of net value added (land, labor, capital, and farm operator income) over time. Net value added by U.S. agriculture grew significantly from $18 billion to 1960 to$95 billion in 1996. We examine regional differences in net value added using the Theil entropy measure. The inequality (dispersion) of net value added increased over time. The increased inequality represented both increases in regional dispersion in net value added and increases in the average inequality in net value added in each region. Thus, the net value added is becoming less alike across the U.S. We also examined the inequality in the components of net value added. The greatest dispersion occurred in returns to land followed by returns to capital. Therefore, changes in the dispersion of net value added by agriculture are explained by differences in the payments to non-operator landlords and to capital.Agricultural Finance,

A late-time transition in the cosmic dark energy?

We study constraints from the latest CMB, large scale structure (2dF, Abell/ACO, PSCz) and SN1a data on dark energy models with a sharp transition in their equation of state, w(z). Such a transition is motivated by models like vacuum metamorphosis where non-perturbative quantum effects are important at late times. We allow the transition to occur at a specific redshift, z_t, to a final negative pressure -1 < w_f < -1/3. We find that the CMB and supernovae data, in particular, prefer a late-time transition due to the associated delay in cosmic acceleration. The best fits (with 1 sigma errors) to all the data are z_t = 2.0^{+2.2}_{-0.76}, \Omega_Q = 0.73^{+0.02}_{-0.04} and w_f = -1^{+0.2}.Comment: 6 Pages, 5 colour figures, MNRAS styl

Agricultural Profits and Farm Household Wealth: A Farm-level and Cross-sectional Analysis

This study examines the relationship between agricultural profits and farm household wealth across locations and farm sizes in U.S. agriculture. Farmland has out-performed non-farm investments over the past decade. Thus, households may want to keep their farmland to build wealth, even if it requires them to earn off-farm income.Land Economics/Use,