GIOTTO's antenna de-spin mechanism: Ots lubrication and thermal vacuum performance

Except in the near Earth phase of GIOTTO's mission to Comet Halley, the HGA (high gain antenna) on board GIOTTO was the only designed means of up/down communications. The spacecraft spin stabilization required that the HGA be despun at the same rotational rate of nominally 15 rpm in order to keep the HGA pointing accurately to a Earth. A dual servomotor despin mechanism was designed and built by SEP of France for this purpose. The expected thermal environment suggested that dry lubrication was preferable to wet for the ball bearings but there existed no relevant data on the torque noise spectrum of candidate solid lubricants. Therefore ad hoc torque noise tests were run with two solid lubricants: ion plated lead film plus lead bronze cage (retainer) and a PTFE composite cage only. The lead lubrication showed the better spectrum up to the mission lifetime point so it was selected for continued test over some 20 times the Halley mission life, with periodic torque spectrum monitoring. The spectrum remained well within the pointing error budget over the 100 million revolutions covered

Effects of Dredge Material Placement on Macroinvertebrate Communities: Phase 1

ID: 8809; issued October 1, 1998INHS Technical Report prepared for Rock Island District, US Army Corps of Engineer

The Endogenous Formation of Coalitions to Provide Public Goods: Theory and Experimental Evidence

This paper examines the endogenous formation of coalitions that provide public goods in which players implement a minimum participation requirement before deciding whether to join. We demonstrate theoretically that payoff-maximizing players will vote to implement efficient participation requirements and these coalitions will form. However, we also demonstrate that if some players are averse to inequality they can cause inefficient outcomes. Inequality-averse players can limit free riding by implementing larger than efficient coalitions or by blocking efficient coalitions from forming. We test the theory with experimental methods and observe individual behavior and coalition formation consistent with a model of inequality-averse players. Key Words:

NY Pollution Discharge Elimination Permits for CAFOs, Management Adjustments and the Environment

Weakening demand for livestock and dairy produce, historically high prices for feed ingredients and increasingly strict regulations on animal waste management continue to put significant pressure on livestock and dairy operating margins. In this paper, we use representative farm mathematical programming models to analyze important linkages between farm management adjustments and changes in farm income due to recent changes in relevant agricultural prices and restrictions on land application of nutrients. We account explicitly for new restrictions on land application of nitrogen and phosphorus, and specifically applied to confined animal feeding operations (CAFOs). Our mathematical methods and the distinctive data available allows for the assessment of the effects on income and environmental nutrient loading for New York State dairy production farms. The results suggest that with current relative prices for feed ingredients, adjustments to dairy rations lead to increased nitrogen and phosphorus content in dairy waste and soil nutrient levels being applied well in excess of crop requirements. While the regulations will correct for this problem at the farm level, our results indicate that CAFOs could experience significant losses in income. These losses depend critically on the cost of off-site manure disposal. Our results also demonstrate that significant risks of excess nutrient loading remain during extreme weather events.CAFO regulations, nutrient management, manure disposal, mathematical programming, environmental quality, Environmental Economics and Policy, Farm Management, Production Economics,

The Endogenous Formation of Coalitions to Provide Public Goods: Theory and Experimental Evidence

This paper examines the endogenous formation of coalitions that provide public goods in which players implement a minimum participation requirement before deciding whether to join. We demonstrate theoretically that payoff-maximizing players will vote to implement efficient participation requirements and these coalitions will form. However, we also demonstrate that if some players are averse to inequality they can cause inefficient outcomes. Inequality-averse players can limit free riding by implementing larger than efficient coalitions or by blocking efficient coalitions from forming. We test the theory with experimental methods and observe individual behavior and coalition formation consistent with a model of inequality-averse players.public goods, coalition formation, inequality aversion, participation requirement, experiments

The Replication Argument for Incompatibilism

In this paper, I articulate an argument for incompatibilism about moral responsibility and determinism. My argument comes in the form of an extended story, modeled loosely on Peter van Inwagen’s “rollback argument” scenario. I thus call it “the replication argument.” As I aim to bring out, though the argument is inspired by so-called “manipulation” and “original design” arguments, the argument is not a version of either such argument—and plausibly has advantages over both. The result, I believe, is a more convincing incompatibilist argument than those we have considered previously

Dairy Farm Management Adjustments to Biofuels-Induced Changes in Agricultural Markets

A mathematical programming model of a representative New York dairy farm is developed to identify optimal management adjustments to increased availability of corn distillers dried grains with solubles (DDGS). While at current prices DDGS feeding is limited to dry cows and young stock, as prices decrease, DDGS in lactating cow rations increase from 7.4% to 20% on a dry matter basis. While expected changes in net farm returns are modest, more important is the consideration of changes in nutrient management practices necessary to deal with increasing levels of nitrogen and phosphorus in the animal waste.Production, Management, Agribusiness, Agricultural Finance, Farm Management, Financial Economics, Resource /Energy Economics and Policy,

Simple threshold rules solve explore/exploit trade‐offs in a resource accumulation search task

How, and how well, do people switch between exploration and exploitation to search for and accumulate resources? We study the decision processes underlying such exploration/exploitation trade‐offs using a novel card selection task that captures the common situation of searching among multiple resources (e.g., jobs) that can be exploited without depleting. With experience, participants learn to switch appropriately between exploration and exploitation and approach optimal performance. We model participants' behavior on this task with random, threshold, and sampling strategies, and find that a linear decreasing threshold rule best fits participants' results. Further evidence that participants use decreasing threshold‐based strategies comes from reaction time differences between exploration and exploitation; however, participants themselves report non‐decreasing thresholds. Decreasing threshold strategies that “front‐load” exploration and switch quickly to exploitation are particularly effective in resource accumulation tasks, in contrast to optimal stopping problems like the Secretary Problem requiring longer exploration

Development and testing of porous ionizer materials, part I Summary report, Feb. 1965 - May 1966

Development and testing of porous tungsten ionizer materials for cesium contact engine