Hybrid propulsion technology program: Phase 1, volume 1

A number of booster propulsion system concepts are being considered for the next generation of manned and unmanned space launch vehicles. The one propulsion system concept that has potential for reducing costs with increased safety, reliability, and performance is hybrid propulsion (HP). A HP system may be thought of as a liquid propulsion system with solid fuel or a solid propulsion system with a liquid oxidizer. The liquid propulsion features that are most attractive are the higher specific impulse, clean exhaust, separated propellants, and oxidizer loading just prior to launch. The most attractive solid propulsion features includes low life cycle costs, no rotating machinery, compact size, and a robust case. In addition, a HP system has a robust LO2 tank; provides thrust control for ignition, to alleviate flight loads, and for thrust termination; and uses an inert grain that is not sensitive to anomalies such as cracks, voids, and separations. The object is to develop the technology to enable the application of HP to manned and unmanned space launch vehicles. This program will identify the necessary technology, acquire that technology, and demonstrate that technology. This volume is the executive summary

Hybrid propulsion technology program: Phase 1. Volume 3: Thiokol Corporation Space Operations

Three candidate hybrid propulsion (HP) concepts were identified, optimized, evaluated, and refined through an iterative process that continually forced improvement to the systems with respect to safety, reliability, cost, and performance criteria. A full scale booster meeting Advanced Solid Rocket Motor (ASRM) thrust-time constraints and a booster application for 1/4 ASRM thrust were evaluated. Trade studies and analyses were performed for each of the motor elements related to SRM technology. Based on trade study results, the optimum HP concept for both full and quarter sized systems was defined. The three candidate hybrid concepts evaluated are illustrated

Foraging Behavior of Swainson\u27s Thrushes (Catharus ustulatus) During Spring Migration through Arkansas

Foraging behavior of Swainson’s Thrushes on spring migration was studied in western Arkansas in the spring of 2013 and 2014. Observations were made in two forested field sites, one of them urban and the other suburban. The former had a significantly higher woody stem area (cm2) than the latter. For each foraging observation, the following three parameters were noted: Foraging Stratum (Ground, Shrub, Sapling, Sub canopy, and Canopy); Foraging Substrate (Ground/Litter, Herb, Foliage, Bark, and Air); and Foraging Maneuver (Glean, Probe, Dive/Glean, Hover, Jump Hover, and Hawking). We tested the hypotheses that these foraging variables differed significantly between the urban and suburban sites, and between the two years. These hypotheses were rejected for all three parameters. The consolidated data from both the sites and years revealed that a significantly higher proportion (67%) of the observations were on the Ground stratum, compared to the Shrub (13.7%) and Sapling strata (13%). Similarly, a significantly higher proportion (66%) of the foraging substrate used was Ground/Litter, followed by Foliage (16.7%) and Bark (15.8%). Gleaning was the most common foraging maneuver used (71.5%), and was significantly higher than Probing (12.3%) and Dive Gleaning (8.4%)

Some common butterflies of the Nairobi district

Volume: XVI

Apollo experience report: Development of guidance targeting techniques for the command module and launch vehicle

The development of the guidance targeting techniques for the Apollo command module and launch vehicle is discussed for four types of maneuvers: (1) translunar injection, (2) translunar midcourse, (3) lunar orbit insertion, and (4) return to earth. The development of real-time targeting programs for these maneuvers and the targeting procedures represented are discussed. The material is intended to convey historically the development of the targeting techniques required to meet the defined target objectives and to illustrate the solutions to problems encountered during that development

Reuse as heuristic : from transmission to nurture in learning activity design

In recent years a combination of ever more flexible and sophisticated Web technologies and an explosion in the quantity of online content has sparked learning technologists around the world to pursue the promise of the 'reusable learning object' or RLO with the idea that RLOs could be reused in different educational contexts, thereby providing greater overall flexibility and return on investment. In 2002 the ACETS Project undertook a three-year study in the UK to investigate whether RLOs worked in practice and how the pursuit of reuse affected the teacher and their teaching. Teachers working in healthcare-related subjects in Higher and Further Education were asked to create an original learning design or activity from third-party digital resources and to reflect both on the process and its outcomes. The expectation was that teachers would be the ones selecting and reusing third-party materials. This paper describes how one of the ACETS exemplifiers reinterpreted this remit, challenged the anticipated transmissive model of learning, and instead, gave their students an opportunity to create their own original learning designs and learning activities from third-party digital resources. By describing the educational enhancements, the resulting heightened levels of critical thinking, and sensitivity to patient needs, 'reuse' will be shown to be an effective heuristic for student self-direction and professional development

Analysis of Hydrologic Data for the White River Basin

The value of the natural resources of the White River Basin (Basin), AR is recognized by the area's designation as a "Wetland of International Importance". The Basin constitutes one of the Nation's largest remaining intact forested wetland landscapes, second only to the Atchafalya Basin. It supports the North American continent's largest concentration of over-wintering mallard ducks, a world-class trout fishery, the last vestige of a big river fishery remaining in the Mississippi River Basin, and numerous threatened and endangered species. The continued viability of this wetland ecosystem depends on the suitability of the hydrologic environment to the resident flora and fauna. Numerous modifications of the Basin hydrologic features in the past century have seriously impaired the sustainability of these resources. The Basinwide alterations of hydrologic processes (e.g., impoundment and regulatory releases of flows and volumes in the upper reaches, navigational modifications of lower reaches, and consumptive demands for agricultural use throughout) have affected the hydrology of the system profoundly. The result is highly regulated flows and stages, vastly altered hydrologic patterns, over-stabilized water levels, and disruption of seasonal water distribution patterns. Given the critical nature of hydrology in regulating the structure and function of wetland ecosystems, the impacts have been devastating, particularly to the critical bottomland hardwoods that support the Basin's fish and wildlife resources. To date these piece-meal, system-wide, hydrologic alterations have cornmutatively degraded the habitat value of this resource for fish and wildlife in the Basin, and have lead to changes in their numbers and distributions. In spite of the enormous stakes involved, there has been no comprehensive characterization of the Basin hydrology. System alterations such as channel deepening, dam construction, water allocation plans, and flood control measures are currently pending. These projects will potentially hrther modify the hydrologic environments of the Basin, and no doubt require mitigation measures. In addition, there is genuine interest in restoring aspects of the Basin's historic hydrologic regime within some set of reasonable limits. In order to proceed with this effort, the anticipated effects of these modifications and restorations on the Basin ecology require thorough study of the area's historic hydrology, so that connectivity among Basin precipitation patterns, flow fluctuations, and land use changes can be made. A basin hydrologic characterization is an initial component of this effort. The focus of this effort was to determine and assemble the data set from which characterization of the hydrologic environments of the Basin using historic and recent water level, flow, (primarily by USGS-WRD) at locations throughout the Basin could proceed. ( Document has 11 pages.

A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment

A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems