Digital receiver simulation

Digital simulation of the data link for the Saturn-Uranus spacecraft design is summarized. The data link is a 40 watt, 400 MegaHertz, 44 bit-a-second link, a power starved link, and uses convolution coding. Aspects of the link of particular interest are atmospheric scintillation and the Doppler to data rate ratio. The major characteristics of the scintillation are modeled in terms of tapped delay lines. A candidate system design and receiver design is developed. A computer flow diagram depicting a routine for the error rate and one for acquisition is presented. Various coding algorithms are analyzed since the convolution code is sensitive to the distribution of error and the actual pattern of the error

Communications constraints on a Jupiter probe mission

The use of the Saturn Uranus telemetry design for Jupiter entry requires the following qualifications in space probe data handling: A single dump substitute for the dual damp, a reduction in the neutral mass spectrometer rate, and providing that a second burn is made, a delta V correction

Sustainability and community food systems in four Iowa counties

Four Iowa counties (Benton, Marshall, Audubon and Johnson) were studied to determine how local food systems had developed, prospered, or struggled in the face of challenges from globalization and industrialization

A Multiple Stakeholder View of the Potential for Hoop Structures in Iowa Swine Production

A survey of Iowa farmers and nonfarmers was conducted to determine public perceptions about the potential impacts of hoop structures on Iowa swine production and support for public research on hoop structures. Stakeholder groups included hog farmers using hoop structures; hog farmers not using hoop structures, farmers not raising hogs; veterinarians, vocational agricultural teachers, and agricultural lenders; and Iowa State University Extension personnel. Of the groups, hoop users most consistently saw favorable impacts on farm profits, public concern about animal welfare, farm quality of life, risk of water pollution, and odor reduction. Of the impact areas, all groups were most likely to see favorable impacts of hoop structures in reducing the risk water pollution problems. Except for ISU extension personnel, less than half of each stakeholder group, including hoop users themselves, said taxpayer money should be used for hoop structures research. This study indicates generally favorable assessments about the impacts of hoop structures, especially in the environmental area, but no strong position on the part of these stakeholder groups that public agricultural research should be dedicated to hoop structures

Predicting the outcome of renal transplantation

ObjectiveRenal transplantation has dramatically improved the survival rate of hemodialysis patients. However, with a growing proportion of marginal organs and improved immunosuppression, it is necessary to verify that the established allocation system, mostly based on human leukocyte antigen matching, still meets today's needs. The authors turn to machine-learning techniques to predict, from donor-recipient data, the estimated glomerular filtration rate (eGFR) of the recipient 1 year after transplantation.DesignThe patient's eGFR was predicted using donor-recipient characteristics available at the time of transplantation. Donors' data were obtained from Eurotransplant's database, while recipients' details were retrieved from Charite Campus Virchow-Klinikum's database. A total of 707 renal transplantations from cadaveric donors were included.MeasurementsTwo separate datasets were created, taking features with <10% missing values for one and <50% missing values for the other. Four established regressors were run on both datasets, with and without feature selection.ResultsThe authors obtained a Pearson correlation coefficient between predicted and real eGFR (COR) of 0.48. The best model for the dataset was a Gaussian support vector machine with recursive feature elimination on the more inclusive dataset. All results are available at http://transplant.molgen.mpg.de/.LimitationsFor now, missing values in the data must be predicted and filled in. The performance is not as high as hoped, but the dataset seems to be the main cause.ConclusionsPredicting the outcome is possible with the dataset at hand (COR=0.48). Valuable features include age and creatinine levels of the donor, as well as sex and weight of the recipient

Digital simulation of a communication link for Pioneer Saturn Uranus atmospheric entry probe, part 2

For abstract, see N75-26198

Preentry communications study. Outer planets atmospheric entry probe

A pre-entry communications study is presented for a relay link between a Jupiter entry probe and a spacecraft in hyperbolic orbit. Two generic communications links of interest are described: a pre-entry link to a spun spacecraft antenna, and a pre-entry link to a despun spacecraft antenna. The propagation environment of Jupiter is defined. Although this is one of the least well known features of Jupiter, enough information exists to reasonably establish bounds on the performance of a communications link. Within these bounds, optimal carrier frequencies are defined. The next step is to identify optimal relative geometries between the probe and the spacecraft. Optimal trajectories are established for both spun and despun spacecraft antennas. Given the optimal carrier frequencies, and the optimal trajectories, the data carrying capacities of the pre-entry links are defined. The impact of incorporating pre-entry communications into a basic post entry probe is then assessed. This assessment covers the disciplines of thermal control, power source, mass properties and design layout. A conceptual design is developed of an electronically despun antenna for use on a Pioneer class of spacecraft

Socio-technical and environmental dimensions of swine manure management decisions

Once strictly a farm management concern, manure management is now a matter of state and societal interest. This qualitative study examines why and how farmers in two Iowa watersheds make decisions about manure management for their operations. Farmers interviewed explained the motives, logic, opportunities, and constraints that guide their use of particular management practices