COFS 1: Beam dynamics and control technology overview

The Control of Flexible Structures (COFS) 1 Project provides the invaluable opportunity to test, validate, and measure the effectiveness of theories, structural concepts, control systems, and flight certification processes for future missions through a research program focusing on multiple issues in large flexible structures, dynamics, and controls. The COFS 1 Project consists of a series of ground and flight activities building progressively from modeling and dynamic characterization of large space systems to the more complex issues of flexible-body control. The program objectives are to: determine the degree to which theory and ground testing can predict flight performance of next-generation low-frequency structures; evaluate structural fidelity of representative next-generation large deployable precision structure; assess math modeling requirements for large lightweight complex systems on which ground test results are questionable; determine degree to which scale model analysis and tests can be correlated to full-scale performance; evaluate system identification and state estimation algorithms on complex lightweight structures in the space environment; evaluate and verify controls/structures modeling capability; evaluate control laws and control systems; and evaluate damping effects in micro-g environment

PUBLIC LAND POLICY AND THE VALUE OF GRAZING PERMITS

This article provides an empirical test of the traditional theory of permit value and investigates the impact of recent changes in public land policies on the value of grazing permits. Results suggest that the cost advantage for grazing on public lands has been capitalized into substantial permit values, but other economic and hedonic factors influencing land prices also have contributed to the value of grazing permits. Public land grazing permits have fallen in value relative to deeded land as grazing fees have increased and as assurance has waned that public land policies will continue to be favorable to ranchers.Land Economics/Use,

A Review of the Open Educational Resources (OER) Movement: Achievements, Challenges, and New Opportunities

Examines the state of the foundation's efforts to improve educational opportunities worldwide through universal access to and use of high-quality academic content

OFFERING FOOD DISTRIBUTION-RELATED COURSES IN AGRICULTURAL ECONOMICS CURRICULA: PERSPECTIVES FROM ACROSS THE U.S.

Teaching/Communication/Extension/Profession,

RANGELAND ECONOMICS, ECOLOGY, AND SUSTAINABILITY: IMPLICATIONS FOR POLICY AND ECONOMIC RESEARCH

Environmental Economics and Policy, Land Economics/Use,

An Investigation Of The Recent Deterioration Of I-75 In Scott County

In early January of 1999, approximately 15 miles ofl-75 in Scott County began to rapidly deteriorate. The existing pavement exhibited several potholes and delaminations. The worst section of deterioration fell approximately between milepoints 125 and 133. In the latter part of January, the condition of the highway had declined to the point thatcorrective action was necessary. The worst sections were milled and patched with hotmixasphalt (HMA). Despite this temporary improvement to the pavement condition, adesire developed within the Department to investigate the cause of the deterioration inorder to prevent a future similar occurrence. Therefore, personnel from the Division of Materials and the Kentucky Transportation Center conducted an abbreviated investigation of the deteriorating pavement and theasphalt mixtures involved. The findings from this investigation, including analyses of thehistorical data for these mixtures and testing of the in-place pavement, revealed severalpossibilities for the premature pavement failure. These possibilities included questionable quality of the aggregates in the mixtures, lowasphalt contents and high dust contents, poor volumetric properties of the mixtures, andlow in-place densities and high permeability of the existing pavement. It was concludedthat no single deficiency caused the failure, but rather, a combination of several factors. A companion section of I-7 5 immediately south of the deteriorated Scott County portions,constructed about one year prior to the pavement presently in question, continues toperform well. Investigation of this pavement and the involved asphalt mixtures revealedhigher asphalt contents, better volumetric properties, higher in-place densities, and lowerpermeability. It is believed that recent revisions to the applicable asphalt mixture specifications have allbut eliminated the possibility of the recurrence of this type of failure. Mixtures designedcurrently under the Superpave system undergo greater scrutiny and must satisfy tougherspecifications. Also, asphalt mixtures are accepted differently today than when thispavement was originally constructed. It is highly unlikely that the mixtures that arecurrently deteriorating on I-75 could satisfy today\u27s specifications

Performance of a Blunt-lip Side Inlet with Ramp Bleed, Bypass, and a Long Constant-area Duct Ahead of the Engine : Mach Numbers 0.66 and 1.5 to 2.1

Unsteady shock-induced separation of the ramp boundary layer was reduced and stabilized more effectively by external perforations than by external or internal slots. At Mach 2.0 peak total-pressure recovery was increased from 0.802 to 0.89 and stable mass-flow range was increased 185 percent over that for the solid ramp. Peak pressure recovery occurred just before instability. The 7 and one-third-diameter duct ahead of the engine reduced large total-pressure distortions but was not as successful for small distortions as obtained with throat bleed. By removing boundary-layer air the bypass nearly recovered the total-pressure loss due to the long duct

Preliminary Investigation of Effect on Performance of Dividing Conical-spike Nose Inlets into Halves at Mach Numbers 1.5 to 2.0

Inserting a splitter plate in the subsonic diffuser caused a pressure-recovery loss of about 1 percent for an inlet with a long nearly constant-area throat section. The loss was due to the increased surface area. Another inlet, which had a comparatively rapid area increase immediately after the throat, experienced pressure-recovery losses of 5 and 6 percent at Mach numbers of 1.8 and 2.0, respectively, and about 1 percent at Mach 1.5

Fundamental and Applied Experimental Investigations of Corrosion of Steel by LBE under Controlled Conditions: Kinetics, Chemistry Morphology, and Surface Preparation

Advanced nuclear processes and facilities (e.g., transmutation of nuclear waste, fast reactors, and spallation neutron sources) impose special demands on materials, which must withstand high temperatures, high radiation fields, and chemical corrosion. Proposed schemes for transmuting nuclear waste require a nonmoderating coolant such as lead-bismuth eutectic (LBE) or liquid sodium. While LBE corrodes most steels, small amounts of oxygen in the LBE greatly reduces the corrosion rate, and could ideally re-grow a damaged oxide layer in situ. The protective oxide layer would thus be self-healing. However, a fundamental understanding of the role of oxygen and passivating oxide layers is presently incomplete. During the past year, gas-phase experiments were conducted in which steel samples were oxidized in glass capsules at elevated temperatures in a tube furnace. Corroded steel samples were analyzed from a variety of sources, including the Delta loop at LANL and samples corroded at UNLV in the gas phase experiments