2,153 research outputs found
CIS-lunar space infrastructure lunar technologies: Executive summary
Technologies necessary for the creation of a cis-Lunar infrastructure, namely: (1) automation and robotics; (2) life support systems; (3) fluid management; (4) propulsion; and (5) rotating technologies, are explored. The technological focal point is on the development of automated and robotic systems for the implementation of a Lunar Oasis produced by Automation and Robotics (LOAR). Under direction from the NASA Office of Exploration, automation and robotics were extensively utilized as an initiating stage in the return to the Moon. A pair of autonomous rovers, modular in design and built from interchangeable and specialized components, is proposed. Utilizing a buddy system, these rovers will be able to support each other and to enhance their individual capabilities. One rover primarily explores and maps while the second rover tests the feasibility of various materials-processing techniques. The automated missions emphasize availability and potential uses of Lunar resources, and the deployment and operations of the LOAR program. An experimental bio-volume is put into place as the precursor to a Lunar environmentally controlled life support system. The bio-volume will determine the reproduction, growth and production characteristics of various life forms housed on the Lunar surface. Physicochemical regenerative technologies and stored resources will be used to buffer biological disturbances of the bio-volume environment. The in situ Lunar resources will be both tested and used within this bio-volume. Second phase development on the Lunar surface calls for manned operations. Repairs and re-configuration of the initial framework will ensue. An autonomously-initiated manned Lunar oasis can become an essential component of the United States space program
Impact of Service Learning: High School Students as Health Coaches for Children
The current study examined high school studentsā perceptions of healthy eating and exercise lessons in an obesity prevention curriculum being delivered to children in an urban area. Evaluators assessed high school student perceptions of their service learning. Forty-seven high school students participated and coached 65 children. The high school students recorded their perceptions of their experience by answering a series of questions in their journals after each teaching session. The high school students also recorded the childrenās daily eating and exercise goals, roadblocks to reaching goals, and ideas for overcoming roadblocks. Results indicated that the majority of high school students (n = 45) wanted to participate in service learning in the future and that they were learning about teaching, setting goals with children, and learning about themselves as leaders. Future research should examine the long-term impact of the service experience for the high school students
FEASIBILITY OF A SHEEP COOPERATIVE FOR GRAZING LEAFY SPURGE
This report presents an economic feasibility study of a 5,000 head, cooperatively owned, sheep operation for leafy spurge control. The objectives were 1) determine the return on investment of the cooperative, 2) determine the proposed structure of the cooperative, and 3) ascertain the amount of capital investment required by members in the cooperative. Three sheep flock management alternatives were initially considered for the cooperative. These were 1) winter lambing, 2) spring lambing, and 3) fall lambing. The fall lambing scenario was determined to be infeasible because of logistics associated with gathering and transportation of pregnant ewes and lack of grazing pressure on leafy spurge throughout the grazing season. The total capital investment per ewe for the winter lambing scenario was more than the spring lambing scenario - - 216, respectively. The expected net income generated by the winter lambing scenario was negative. The minimum break-even lamb selling price or lambs sold per ewe for the winter lambing scenario was 124,000 annually. The minimum breakeven lamb selling price or lambs sold per ewe for the spring lambing scenario was $59.51/cwt and 0.94, respectively. The expected return on investment (50% equity) for cooperative members with the spring lambing scenario, assuming a 50-acre leafy spurge infestation in a 100-acre pasture and new fence, was 16 percent (stocking rate of 1 ewe and lambs per acre of leafy spurge). While these returns are not a guarantee of success for the spring lambing alternative, they do provide an indication of the potential that such a cooperative may have.Leafy Spurge, Cooperative, Weed Control, Sheep Grazing, Economics, Farm Management, Resource /Energy Economics and Policy, Agribusiness,
Crashworthy Perforated Square Steel Tube (PSST) Mailbox Support ā Phase I
Federal requirements have made it mandatory that safe mailbox support systems be designed to yield or breakaway whenimpacted by a vehicle. The Nebraska Department of Transportation (NDOT) has previously used a non-proprietary, U-channel post mailbox support that was evaluated at the Midwest Roadside Safety Facility (MwRSF) in the 1980\u27s. NDOT desires that the mailbox support be updated to meet MASH 2016 TL-3 safety performance criteria and be redesigned to use perforated square steel tubing (PSST) for the mailbox support post.
The objective of this research project is to develop a non-proprietary mailbox support using PSST support posts that is MASH TL-3 compliant. Following a literature review, single and double PSST mailbox support prototypes were developed. The performance of these prototypes was investigated through dynamic component testing under impact conditions similar to MASH test no. 3-61 with a non-compliant, surrogate 1100C vehicle. Test no. NMB-1 impacted both the single and dual PSST mailbox supports in a single vehicle pass at angles of 0- and 10 degrees, respectively. Both PSST mailbox support options performed adequately in the dynamic testing with no issues observed with respect to occupant risk values or occupant compartment deformation or penetration. Recommendations were made following the testing regarding further research and testing of different mailbox configurations and critical impact angles
Achieving doctorateness: Is South African higher education succeeding with graduate attributes?
This article applies findings from the recent national review of South African doctoral qualifications to examine ways in which universities interpret the formulation of, and apply in the context of a differentiated higher education system, the graduate attributes established in the qualification standard, in order to achieve the characteristics of ādoctoratenessā. The article explores the concept āgraduate attributesā itself, the extent to which it is manifested in institutional, supervisory and examination practices, and how the concept is conveyed to and understood by students. National review findings indicate inconsistencies in conceptualisation and application both between and within institutions. In this article, emphasis is placed on the primary need of developing in the doctoral graduate the capacity to enter, as a deep-thinking researcher, into a community of practising peers, whether in the academy or in a profession
Dynamic strength of a modified W-beam BCT trailing-end termination system
W-beam systems utilize end-terminal anchorages to develop tension upstream and downstream of an impact event. However, the capacities of the anchorage components under impact loading are not well known. One such W-beam end anchorage system, the Midwest guardrail system (MGS) trailing-end anchorage, was evaluated using three dynamic component tests _ a soil foundation tube pull test, a breakaway cable terminal (BCT) post splitting test, and an MGS end anchorage system pull test. The peak load recorded during a soil foundation tube test was 193 kN at 56 mm deflection, as measured at the ground line. BCT posts split at loads of 17.8 and 32.9 kN. The end-anchorage tensile capacity was 156 kN, dissipating 64.7 kJ. Results from the component tests were also used to create and validate nonlinear finite element models of the components in order to be used for future design and analysis of end anchorages
Measurement invariance across chronic conditions: a systematic review and an empirical investigation of the Health Education Impact Questionnaire (heiQā¢).
To examine whether lack of measurement invariance (MI) influences mean comparisons among different disease groups, this paper provides (1) a systematic review of MI in generic constructs across chronic conditions and (2) an empirical analysis of MI in the Health Education Impact Questionnaire (heiQ™)
Cable Median Barrier Failure Analysis and Remediation Phase II
Cable median barrier crashes from a total of 12 states were analyzed. Crash data included scene diagrams, photographs, and field measurements, crash narratives, although the availability of data in each crash varied.
Major contributors to penetration crash propensity were identified: diving underride, in which the front end of the vehicle dropped below the bottom cable; prying, in which the vehicle profile caused cable separation or lifting; override; bouncing override, in which the vehicle rebounded after contact with the back slope and bounced over the top of the barrier; system failure, in which one component failure or design failure prevented the cables from adequately engaging the vehicle; and large vehicle crashes, such as tractor trailers, buses, and single-unit trucks into TL-3 systems.
Major contributors to rollover were identified: steep median slopes, in which the slope caused unstable bouncing or abrupt changes in slope profiles acted as trip points for the tires; broadside skid, in which the vehicle was skidding with a sideslip angle of nearly 90 degrees prior to contact with the barrier; contact with post, in which the post acted as a trip point; and other factors such as towing trailer units, median anomalies, or with large vehicles such as tractor-trailers, buses, or motor homes.
Recommended improvements to cable median barrier systems included: minimum top cable height of 35 in. (890 mm); maximum top cable height of 15 in. (381 mm); minimum of 4 cables supported by posts; higher lateral cable-to-post attachment strength at bottom and lower strength at top; low strong-axis strength post sections; and to eliminate cable entrapment in a vertical slot in the post when initial cable contact occurs at a post location.
A summary of factors and how they contributed to penetration, rollover, and severe crash probability is shown in Table 1
Determination of a correlation for predicting lean blow off limits of gaseous fueled, premixed turbulent jet flame arrays enclosed in a hexagonal dump combustor
Combustion of natural gas with air in gas turbines is a key technology for efficient provision of electric energy and heat. More stringent regulations regarding the emission of pollutants, such as NOx emissions, are necessitating research on technologies to reduce NOx formation during the combustion process. One technical approach onto the reduction of NOx-formation during combustion is fuel-lean premixed combustion.
Current lean combustion concepts applied in stationary gas turbine combustors rely on flame stabilization through recirculation of hot flue gas using swirling flows. Swirl stabilized flames may be prone to combustion instabilities especially in lean premixed arrangements. Therefore, another approach is followed in the present study. In this concept, a matrix of turbulent lean premixed jet flames in a dump combustor is applied. The matrix burner consists of a nozzle with an array of circular channels in a hexagonal arrangement and a combustion chamber with a hexagonal cross section. In order to develop an appropriate burner design based on this concept, the experimental determination and theoretical evaluation of the lean blow out limit using different nozzles and operating conditions were conducted in this work in order to quantify the influence of different parameters on the flame stability. The varied geometric parameters are the diameter of the circular channels in the burner matrix as well as the ratio of the free cross section area of the nozzle to the cross section are of the combustion chamber, the combustor area dump ratio. The lean blow limit was determined at different preheating
temperatures and flow velocities. The results show that the velocity at the LBO limit increases with increasing channel diameter, area combustor dump ratio and preheating temperature. The experimental results of three matrix burner are correlated in terms of
a critical Damkoehler number and it is shown through experimental validation, that the Damkoehler number correlation derived is capable of predicting the LBO of a scaled matrix burner
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