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Wind tunnel tests were conducted to determine the aerodynamic heating created by gaps in the reusable surface insulation (RSI) thermal protection system (TPS) for the space shuttle. The effects of various parameters of the RSI on convective heating characteristics are described. The wind tunnel tests provided a data base for accurate assessment of gap heating. Analysis and correlation of the data provide methods for predicting heating in the RSI gaps on the space shuttle.

For abstract, see N75-28103.

This paper employs a stochastic metafrontier framework to examine technical efficiencies and technology gaps of Nepalese farmers in different agro-ecological regions. On average, the technical efficiency level derived from the regional frontier is 81%, from the metafrontier it is 57%, and the technological gap ratio is 70%. There is therefore a clear opportunity to improve the performance of farming households within regions through improving farmer's education, farming experiences, and by adopting climate change adaptation practices. Also indicated is that agricultural policies should be developed to reduce the technology gap between specific regions and the overall agricultural sector. In this context, this study highlights the need to improve farmers’ access to agricultural markets, livelihood diversification and strengthening social capital such as farmers’ participations in relevant agricultural organizations.

Heat transfer data measured in gaps typical of those under consideration for joints in space shuttle reusable surface insulation protection systems have been assimilated, analyzed and correlated. The data were obtained in four NASA facilities. Several types of gaps were investigated with emphasis on simple butt joints. Gap widths ranged from 0.07 to 0.7 cm and depths ranged from 1 to 6 cm. Laminar, transitional and turbulent boundary layer flows over the gap opening were investigated. Three-dimensional heating variations were observed within gaps in the absence of external flow pressure gradients. Heat transfer correlation equations were obtained for several of the tests. Thermal protection system performance with and without gaps was compared for a representative shuttle entry trajectory.

Heat transfer data measured in gaps representative of those being employed for joints in the space shuttle reusable surface insulation (RSI) thermal protection systems (TPS) were assimilated, analyzed, and correlated. Several types of gap were investigated with emphasis on simple butt joints. Gap widths ranged from 0.0 to 0.76 cm and depths ranged from 1 to 6 cm. Laminar, transitional, and turbulent boundary layer flows over the gap opening were investigated. The angle between gap axis and external flow was varied between 0 and pi/2 radians. The contoured cross section gap performed significantly better than all other wide gaps and slightly better than all other narrow gap geometries. Three dimensional heating variations were observed within gaps in the absence of external flow pressure gradients. Interactions between heating within gaps and heating of adjacent top tile surfaces were observed. Gaps aligned with the flow were observed to promote boundary layer transition. Heat transfer correlation equations were obtained for many of the tests. The TPS thickness requirements with and without gaps were computed for a current shuttle entry trajectory. Experimental data employed in the study are summarized. A description of each test facility, run schedule and test conditions, model descriptive information, and heat flux data are included.

Lifelong learning has become an integral part of educational approaches, aiming to promote continuous learning throughout an individual's life. The purpose of the current literature review is to assess the trends, themes and gaps in lifelong learning for engineers. A comprehensive search was conducted in Google Scholar, ScienceDirect, and Scopus for articles published from 1990. Specific search terms were used to retrieve relevant articles and were determined based on a combination of keywords. The abstracts and titles of the retrieved articles were screened to determine their eligibility for inclusion in this study. A total of 5,342 studies were initially identified. After removing duplicates, the number of studies was reduced to 2,217. Subsequently, the studies were further filtered based on the predefined qualification criteria, resulting in 1,779 studies that underwent abstract and title screening. Ultimately, a total of 28 articles were identified as meeting the predefined eligibility criteria and were considered for the research. These selected articles formed the basis for the thematic analysis and further exploration of the research topic. The studies emphasized the significance of both formal and informal learning and training. Problem-based learning is a crucial component of lifelong learning. This approach encourages deeper understanding, independent thinking, and the development of teamwork and essential skills. Self-directed learning is a prominent competency for lifelong learning. It involves self-reflection, self-regulation, and proactively identifying areas for improvement. A group-based approach is suggested to complement technical knowledge with personal skills and non-technical competencies. Five themes including self-directed learning, coaching and mentoring, problem-based learning, formal and informal learning, and group-based approaches were identified. These concepts should be integrated into the education system and the workplace to support lifelong learning for engineers. [For the full proceedings, see ED652261.]

Within NASA, exploration capability gaps are defined as the difference between the current state-of-the-art in capabilities and the anticipated needs of future human spaceflight architectures. As NASA and its partners’ capabilities for human exploration of deep space continue to mature, it is necessary to understand the capability gaps that require closure to support future habitation systems, such as the Lunar Surface Habitat (SH) and Mars Transit Habitat (TH) currently in concept development. This paper will identify high-priority capability gaps for exploration habitation and show potential options for gap closure through investment in technology, development, and testing. High-priority capability gaps are divided into the following general taxonomy areas: human health/life support/habitation systems, flight computing and avionics, power and energy storage, communications and navigation, thermal management systems, human exploration destination systems, autonomous systems, sensors and instruments, GNC (guidance, navigation, and control), robotic systems, ground and uncrewed surface systems, and materials/structures/mechanical systems/manufacturing. In the gap identification process, teams of discipline experts from across NASA reviewed the latest habitation architecture needs against current capabilities to understand where gaps may exist. The results of the assessment established a basis for the current state-of-the-art within each gap and identified the capability needs of the proposed exploration missions the gap links to. An assessment of how each test platform (e.g., Ground, International Space Station (ISS), Commercial Low Earth Orbit (LEO) Destinations, Gateway) may be leveraged to mature capabilities and potentially provide a route to gap closure will be discussed. The notional timeline for gap closure to support reference missions and impacts to overall schedule are also assessed where appropriate. Based on the capability gap analysis described above, the paper summarizes important technology maturation considerations for human exploration architectures, with a focus on the Mars TH. The previously published NASA habitation ground rules and assumptions document is used as the basis to classify gaps as enabling, enhancing, or “push” opportunities for a particular architecture. Stepwise technology maturation plans/considerations are presented for some selected critical gaps. Overall, the analysis in this paper is intended to help influence development priorities for habitation systems, where high-priority, critical gaps are those currently assessed as having a low probability of closure by the anticipated need date. Capability gap analysis also informs the risk register for exploration habitation systems and mitigation strategies to ensure readiness of key technologies to support future mission timelines. Linkage between capability gaps for Moon and Mars is noted, as closure of a gap at a Lunar destination may subsequently enable or enhance Mars TH architectures.

The goal of the current study is to identify scenarios for which thermal and moisture effects become significant in the loading of a composite structure. In the current work, a simple configuration was defined, and material properties were selected. A Fortran routine was created to automate the mesh generation process. The routine was used to create the models for the initial mesh refinement study. A combination of element length and width suitable for further studies was identified. Also, the effect of the overlap length and gap length on computed shear and through-thickness stresses along the bondline of the joints was studied for the mechanical load case. Further, the influence of neighboring gaps and overlaps on these joint stresses was studied and was found to be negligible. The results suggest that for an initial study it is sufficient to focus on one configuration with fixed overlap and gap lengths to study the effects of mechanical, thermal and moisture loading and combinations thereof on computed joint stresses

For abstract, see N75-28103.