159 research outputs found

    New and rare Schizomida (Arachnida: Hubbardiidae) from South America

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    One new genus and eight new species of Schizomida are described from South America: Adisomus duckei n.g., n.sp. from Brazil, Rowlandius sul n.sp. from Brazil, Surazomus arboreus n.sp. from Brazil, S. manaus n.sp. from Brazil, S. mirim n.sp. from Brazil, and S. rodriguesi n.sp. from Brazil; Hansenochrus guyanensis n.sp. from Guyana; and Surazomus boliviensis n.sp. from Bolivia. New records of Surazomus brasiliensis (KRAUS) are included and the female genitalia are illustrated

    Simulation verification techniques study: Simulation performance validation techniques document

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    Techniques and support software for the efficient performance of simulation validation are discussed. Overall validation software structure, the performance of validation at various levels of simulation integration, guidelines for check case formulation, methods for real time acquisition and formatting of data from an all up operational simulator, and methods and criteria for comparison and evaluation of simulation data are included. Vehicle subsystems modules, module integration, special test requirements, and reference data formats are also described

    Simulation verification techniques study. Subsystem simulation validation techniques

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    Techniques for validation of software modules which simulate spacecraft onboard systems are discussed. An overview of the simulation software hierarchy for a shuttle mission simulator is provided. A set of guidelines for the identification of subsystem/module performance parameters and critical performance parameters are presented. Various sources of reference data to serve as standards of performance for simulation validation are identified. Environment, crew station, vehicle configuration, and vehicle dynamics simulation software are briefly discussed from the point of view of their interfaces with subsystem simulation modules. A detailed presentation of results in the area of vehicle subsystems simulation modules is included. A list of references, conclusions and recommendations are also given

    Technique for Predicting the RF Field Strength Inside an Enclosure

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    This Memorandum presents a simple analytical technique for predicting the RF electric field strength inside an enclosed volume in which radio frequency radiation occurs. The technique was developed to predict the radio frequency (RF) field strength within a launch vehicle's fairing from payloads launched with their telemetry transmitters radiating and to the impact of the radiation on the vehicle and payload. The RF field strength is shown to be a function of the surface materials and surface areas. The method accounts for RF energy losses within exposed surfaces, through RF windows, and within multiple layers of dielectric materials which may cover the surfaces. This Memorandum includes the rigorous derivation of all equations and presents examples and data to support the validity of the technique

    Technique for Predicting the RF Field Strength Inside an Enclosure

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    This Memorandum presents a simple analytical technique for predicting the RF electric field strength inside an enclosed volume in which radio frequency radiation occurs. The technique was developed to predict the radio frequency (RF) field strength within a launch vehicle's fairing from payloads launched with their telemetry transmitters radiating and to the impact of the radiation on the vehicle and payload. The RF field strength is shown to be a function of the surface materials and surface areas. The method accounts for RF energy losses within exposed surfaces, through RF windows, and within multiple layers of dielectric materials which may cover the surfaces. This Memorandum includes the rigorous derivation of all equations and presents examples and data to support the validity of the technique

    Reliability-Based Electronics Shielding Design Tools

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    Shielding design on large human-rated systems allows minimization of radiation impact on electronic systems. Shielding design tools require adequate methods for evaluation of design layouts, guiding qualification testing, and adequate follow-up on final design evaluation

    Water Quality Hydrology of Lands Receiving Farm Animal Wastes

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    A significant pollution potential from cattle manure has developed as a result of the cattle feeding industry progressing to large, high density feeding operations. Two major potential sources of pollution from beef feedlots is storm runoff and solid waste (manure). The objectives of this research were to determine the characteristics of storm runoff from a beef feedlot, to determine the nitrogen transformations and ammonia volatilization from soils receiving large manure applications, to determine the chemical quality of surface runoff and groundwater from plots receiving large manure applications, to evaluate techniques of deep plowing large amounts of manure into the soil, and to determine the crop quality and yields on field plots receiving large manure application rates. Feedlot runoff was found to carry large amounts of chemical elements. The concentrations of chemical elements did not vary with size and intensity of rainstorm as much as by differences in topography of the watersheds. More ammonia was volatilized from limed soil columns than unlimed but an unexplained decrease in total nitrogen of 10 to 20 percent occurred in the unlimed and limed soil columns, respectively. A 30-in. moldboard plowing 30 to 36-in. deep can safely turn under up to 900 tons/acre of manure and not create a major surface water pollution problem. An increase of chemical elements in the groundwater occurred during the first year and then were reduced to initial values during the second year. No N03 pollution of groundwater occurred. Crops can be effectively grown on land receiving up to 900 tons/acre of manure. Peak yields will not be obtained the first year after plowing the 900 tons under, but yields will increase the second and third years

    Arachnida at "Reserva Ducke", Central Amazonia/Brazil

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    The class Arachnida contains 11 recent orders: Acari, Amblypygi, Araneae, Opiliones, Palpigradi, Pseudoscorpiones, Ricinulei, Schizomida, Scorpiones, Solifugae and Uropygi (Thelyphonida). In total, >570 families, >9165 genera and >93455 species are known world-wide. More than 136 families, >482 genera and >1547 described species occur in Amazonia. Data show, that almost one-fourth of the families presently known in the Arachnida and about 2% of the worlds described species are represented in Amazonia. In the forest reserve 'Reserva Ducke' near Manaus, the Acari-Oribatida represent 45 families, 72 genera and 35 described species, the Aranea 30 families, 143 genera and 295 described species, the Opiliones 5 families, 7 genera and 8 decribed species, the Scorpiones 2 families, 4 genera and 5 described species, the Pseudoscorpiones 6 families, 11 genera, and 15 described species, the Schizomida, 1 family, 2 genera and 2 described species, and the Amblypygi, Palpigradi, Solifugae and Uropygi (Thelyphonida) one species each. Most names are liste

    Response of Peanuts to Irrigation Management at Different Crop Growth Stages

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    Past irrigation research on peanuts has shown that when the plant is exposed to soil moisture stress at different crop growth stages, different responses seem to exist between the Spanish and the Florunner peanut varieties. The Spanish peanuts appear more susceptible to soil moisture stress during the blooming and pegging stage, while the Florunners seem more susceptible during the late maturation stage. The objective of this experiment was to determine the optimum irrigation schedule for peanuts at different crop growth stages for the Spanish and the Florunner varieties. The yield of the two varieties was evaluated under seven different irrigation treatments including a "no stress" check treatment and a dryland treatment. Each treatment had a different schedule of either irrigating or stressing the peanut plant during one or more of three crop growth stages. The three crop growth stages were: (1) pegging; (2) early maturation; and (3) late maturation. Rainfall during the vegetative and blooming stage ensured adequate moisture for both of the crop growth stages. Evapotranspiration was monitored throughout the life cycle for both peanut varieties. The evapotranspiration was determined using a soil moisture balance equation. Plant growth in the form of dry matter accumulation and leaf area index was also studied for the Spanish variety. No significant differences in the leaf area index existed between the treatments. The dry matter growth analysis showed that an irrigation during the pegging stage resulted in a faster pod weight accumulation during the early maturation stage than if no irrigation occurred during that stage. The yield and evapotranspiration results showed that differences existed between the two peanut varieties. First, for the Spanish variety, the results indicated that soil moisture is needed during the pegging stage to obtain near maximum yields. Treatments with an irrigation during the pegging stage had a greater evapotranspiration and larger yields, than the treatments without an irrigation during this stage. Second, if an irrigation is made during the pegging stage, an additional irrigation during the early maturation stage is unnecessary. Third, an irrigation during the late maturation stage will increase yield if dry climatic conditions normally exist during this stage. In the case of the Florunner variety, the yield results indicated that moisture stress should occur in no more than one of the crop growth stages if yield reductions are to be minimized. Also, an adequate supply of soil moisture during the late maturation stage is absolutely necessary in order to obtain maximum yields for Florunner peanuts. Treatments which had an irrigation during the late maturation stage had a steady evapotranspiration rate during this crop growth stage and had near maximum yields. Treatments which showed a decrease in the evapotranspiration rate during the late maturation stage produced a significantly lower yield

    Comparison of Methods for Determining Soil Hydraulic Characteristics

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    An adequate description of soil moisture movement is necessary for solution of agriculturally oriented problems such as irrigation, drainage and runoff control. Three approaches for determining the hydraulic properties of soil are in situ measurements, laboratory measurements and theoretical models. Field measurements, though representative, have the disadvantages of being costly and time consuming. Laboratory and mathematical processes are more practical but require extensive comparison to field results for evaluation. The purpose of this study was to determine the principle hydraulic properties of a soil of the Norwood Series utilizing the three approaches and to compare the results. The laboratory method selected was centrifugation (Alemi, et al., 1972). Soil cores were centrifuged and the redistribution of water was measured as change in weight with time. Inconsistent results and limited data obtained with this method, consequently, prevented adequate conclusions from being made. Hydraulic conductivity was obtained by measurement of hydraulic head and moisture content of the soil profile in situ with tensiometers and neutron probe, respectively. The theoretical procedure utilized water retentivity curves in conjunction with values of saturated hydraulic conductivity for computing hydraulic conductivity as a function of water content. Saturated hydraulic conductivity was measured in the field using Bouwer's (1961) double-tube method. The pressure-water content curves were obtained with disturbed soil samples for 30 to 80 cm depths and with soil cores for O to 15 cm depths using pressureplate extractors. A combination of laboratory and field measured values for these curves was also used for comparison. The field measurements yielded several relationships between hydraulic conductivity and water content, varying with soil depth. Comparison of calculated values with field data using only the laboratory water retention curves gave mediocre results for the 30 to 80 cm soil depth. However, when the field and laboratory data were combined and the resulting water retention curve was used to calculate hydraulic activity, the correlation was greatly improved. The O to 20 cm soil depth showed good results with both curves. Thus, it appears that this theoretical technique is applicable to soils of the type studied, but the accuracy of the calculated values is quite sensitive to the shape of the water retention curve, the saturated water content value and the saturated hydraulic conductivity value. Thus, accurate measurement of these parameters is necessary for its successful use
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