An expert system for shuttle and satellite radar tracker scheduling

This expert system automates and optimizes radar tracker selection for shuttle missions. The expert system is written in the FORTRAN and C languages on an HP9000. It is portable to any UNIX machine having both ANSI-77 FORTRAN and C language compilers. It is a rule based expert system that selects tracking stations from the S-band and C-band radar stations and the TDRSS east and TDRSS west satellites under a variety of conditions. The expert system was prototyped on the Symbolics in the Automated Reasoning Tool (ART) and ZetaLisp. After the prototype demonstrated an acceptable automation of the process of selecting tracking stations to support the orbit determination requirements of Shuttle missions, the basic ART rules of the prototype were ported to the HP9000 computer using the CLIPS language. CLIPS is a forward-chaining rule-based expert system language written in C. Prior to the development of this expert system the selection process was a tedious manual process and expensive in terms of human resources. Manual tracking station selection required from 1 to 2 man weeks per mission; whereas the expert system can complete the selection process in about 2 hours

Quarry fines minimisation : can we really have 10mm aggregate with no fines?

In 2005, 216 million tonnes of saleable aggregate was produced in the UK; a corresponding 55 million tonnes of quarry fines and 24 million tonnes of quarry waste were also produced. The need to minimise fines production is driven by the Aggregates Levy (which has priced quarry fines out of the market in favour of recycled aggregate) and the Landfill Tax (which has made it expensive to dispose of fines). Attempts to reduce fines production often start with a process optimisation audit; the case study presented illustrates how fines production can be reduced, in this instance by up to 30%. Application of good practice in the crushing plant also helps to reduce fines production, including: reducing the crushing ratio to 6:1 or lower; maintaining uniform feed distribution; choke feeding (for compression crushers); reducing the speed of impact crushers; and reducing the degree of recirculation by increased screening efficiency. Future developments are likely to be driven by the need to respond to climate change. New crusher designs will be more automated, offer improved energy efficiency, have a greater production capacity and improved reliability

YIELD BENEFIT OF CORN EVENT MON 863

Data from field experiments are used to estimate the yield benefit of corn hybrids containing event MON 863 relative to nontransgenic corn hybrids without corn rootworm control and with a soil insecticide for corn rootworm control. Over typical ranges for corn rootworm population pressure, event MON 863 provides a yield benefit of 9-28% relative to no control and of 1.5-4.5% relative to control with a soil insecticide. For a reasonable range of prices and yields, the value of the event MON 863 yield benefit is $25-$75/ac relative to no control and $4-$12/ac relative to control with a soil insecticide, depending on corn rootworm pressure. Because of the low correlation between yield loss and the root rating difference, a common empirical finding when estimating yield loss with root ratings, the 95% confidence intervals around these averages are quite wide. Though on average, event MON 863 has substantial value, the wide confidence intervals imply that farmers will see a wide variety of actual performance levels in their fields. This uncertainty in the realized yield benefit is not due to any property of event MON 863, but rather due to the inherent randomness in the numerous environmental and agronomic factors determining a corn plant's yield and yield response to corn rootworm larval feeding damage.Crop Production/Industries,

ADDITIVE VERSUS PROPORTIONAL PEST DAMAGE FUNCTIONS: WHY ECOLOGY MATTERS

Economic analyses of pests typically assume damage is either additively separable from pest free yield or proportional to it. This paper describes the ecological assumptions required for additive and proportional damage functions to demonstrate that both specifications are reasonable. Ecological research supports a proportional damage function for competitive pests such as weeds, while for insect pests the appropriate damage function depends on the level of pest free yield. Theoretical analysis identifies differences between additive and proportional damage functions in terms of the impact of pest control on output variance and the concavity of output in the pest control input.Pest Economics, Damage Function, Damage Control, Risk Reducing Input, Increasing Returns, Functional Response, Crop Production/Industries, Environmental Economics and Policy,

Estimating Soil Erosion and Fuel Use Changes and Their Monetary Values with AGSIM: A Case Study for Triazine Herbicides

This technical report describes a method to use the AGSIM policy model to estimate changes in soil erosion and diesel fuel consumption for tillage that result from agricultural policy changes. This report uses triazine herbicides as a case study to explain the development of the method and illustrate its use. The method assumes farmers shift their adoption of different tillage systems as a result of the agricultural policy being examined. Based on these shifts in tillage adoption rates, changes in farmer costs, erosion rates, and consumption of diesel fuel for tillage occur. The changes in farm costs are used as input by AGSIM, along with other changes in costs and/or yields due to the agricultural policy being examined. Based on these inputs, AGSIM then projects crop acreage and prices, as well as changes in consumer surplus, that would occur as a result of the policy. Based on projected crop acreage changes, the method estimates changes in soil erosion and consumption of diesel fuel for tillage, as well as the monetary value of soil erosion changes and the carbon dioxide emission changes resulting from the fuel use changes. As an illustration of the method, this report presents an updated assessment of the benefits of triazine herbicides to the U.S. economy. For the base year of 2009, this assessment finds that triazine herbicides provide total benefits to the U.S. economy of $3.8 to$4.8 billion per year. Because the triazine herbicides increase the total supply of corn and sorghum, which decreases grain prices, most of these benefits accrue to consumers, especially the livestock and ethanol industries that are major users of corn. These consumer benefits are the sum of the benefits flowing to everyone along the supply chain--livestock farmers, processors and handlers, distributors, retailers, and final consumers. Triazine herbicides also reduce the use of tillage for crop production and the conversion of land to crop production, which reduces soil erosion from U.S. cropland by 56 to 85 million tons per year. Based on these reductions, triazine herbicides provide $210 to$350 million per year in benefits from reduced soil erosion as part of this total benefit to the U.S. economy. In addition, triazine herbicides reduce consumption of diesel fuel for tillage by 18 to 28 million gallons per year, implying a decrease in carbon dioxide emissions of 180,000 to 280,000 metric tons per year. This total benefit of $3.8 to$4.8 billion is a lower bound on the full value of triazine herbicides to the U.S. economy, because several benefits are not accounted for in this assessment. Among the most substantial benefits missing from this assessment are estimates of the resistance management benefits of triazine herbicides for other herbicides and crops, environmental benefits other than reduced soil erosion, and the benefits to crops not modeled by AGSIM (e.g., sweet corn, sugarcane, citrus, grapes, and other fruits and nuts).

Do Drug Plans Matter? Effects of Drug Plan Eligibility on Drug Use Among the Elderly, Social Assistance Recipients and the General Population

The 1984 Canada Health Act does not require that the provinces subsidize prescription drugs. Many provinces do, however, provide categorical coverage to the elderly, social assistance recipients and others, although the generosity of coverage is highly variable. A system of parallel private insurance covers the non-elderly ineligible for social assistance. In this study, we assessed the socio-economic, health and demographic determinants of private drug insurance. We also assessed the effect of inter- provincial variations in drug insurance coverage for the elderly and low income on variations in drug insurance coverage for the elderly and low income on their drug use. In addition, using instrumental variables methods, we considered the effect of prescription drug insurance coverage status on drug use in the non-elderly population ineligible for social assistance. Consistent with the previous literature, we find that for most seniors and non-indigent, drug coverage has only minor effects on drug use. The drug use of social assistance recipients was, however, sensitive to even relatively modest copayments of $0-$6.prescription drug utilization, copayments, user fees, pharmaceutical cost control

RURAL CREDIT RATIONING AND NATIONAL DEVELOPMENT BANKS IN DEVELOPING COUNTRIES

A common problem in agricultural credit markets in developing countries is the coexistence of a competitive market equilibrium interest rate and credit rationing. The literature typically explains the existence of credit rationing in competitive credit markets using adverse selection and moral hazard. Unfortunately these analyses are not consistent with the empirical reality that developing countries deal with in terms of subsidized credit, especially in the agricultural sector. This paper presents an alternative explanation for credit rationing in the agricultural sector in developing countries based on the fact that the requested loans are usually for small amounts, with many farmers making applications. As a result, the costs of operation increase with the number of loans given, so that inefficiencies in credit allocation occur when national development banks are present. It is shown that credit rationing can be reduced if shutting-down the national development bank is a feasible policy. Two other cases show that a national development bank is welfare-improving if an incentive compatible contract is used.Financial Economics,

An Unbalanced Nested Error Component Model for Estimating Pest Damage Functions and the Value of Rootworm Bt Corn

We apply Antweiler’s (2001) double-nested unbalanced panel data model to estimate a western corn rootworm damage function using data from field trials in Illinois and Nebraska. Results imply that expected yield losses for a one unit difference in the node injury scale are 16.4%. Estimated random year and state effects are statistically significant, as is the estimated random experimental effect. The experimental effect is relatively large indicating the tremendous variability in yield losses at the small scale for plots with the same node injury scale measure of root damage. Using the estimated pest damage function to assess the value of Bt corn for farmers in Nebraska and Illinois, we find that, with a mean yield of 200 bu/ac, a yield CV of 25%, a corn price of $3.50/bu, and a Bt corn technology fee of$16/ac, the value of Bt corn for farmers is $173.35/ac and$156.14/ac under very high and high pest pressure respectively.Crop Production/Industries,

UNBALANCED NESTED COMPONENT ERROR MODEL FOR ESTIMATING PEST DAMAGE FUNCTIONS

A recently developed nested error component model for unbalanced panel data is used to estimate insect damage functions. The model estimates the separate random effects for location and year on the variability of yield loss and has smaller standard errors for the regression coefficient than the comparable OLS model.Crop Production/Industries,