DOD low-thrust mission studies

The space transportation system (STS) will be the principal means of launching USAF spacecraft beginning in the 1980's. Since it is manned and reusable it provides new opportunities for unique approaches for cost effective utilization of its capabilities. The STS also places additional requirements and constraints on advanced spacecraft deployment systems that did not previously exist for expandable launch vehicles. To fully utilize these new capabilities designers must be prepared by having cost effective technologies available. Advanced propulsion technology that would provide flexibility, performance, and economic benefits to future Air Force missions was identified. Both electric and chemical propulsion systems are discussed. An LO2/LH2 stage with a torus LO2 tank and 500 lbf pumb fed engine is high on the list of propulsion technology

Influence of constituent properties and geometric form on behavior of woven fabric reinforced composites

Th potential for woven fabric composite forms to increase the interlaminar strength and toughness properties of laminated composite septems is studied. Experimental and analytical studies were performed on a z-axis fabric

Behavior of composite bolted joints at elevated temperature

Experimental results from an investigation which examines the combined effects of temperature, joint geometry and out-of-plane constraint upon the response of mechanically fastened composite joints are presented. Data are presented for simulated mechanically fastened joint conditions in two laminate configurations fabricated from Hercules AS/3501-6 graphite-epoxy. Strength and failure mode results are presented for the test temperatures of 21 C, 121 C and 177 C and for a range of the geometric parameters W/D and e/D from 3.71 to 7.43 and 1.85 to 3.69, respectively. A hole diameter, D of 5.16 mm was utilized for all tests. Pin bearing tests with out-of-plane constraint were conducted at room temperature only. All elevated temperature data were generated for pin bearing conditions. Ultrasonic C scan inspection of the failed specimens was employed to assess the damage region and to determine failure mode. Comparative data are presented for pin bearing and out-of-plane constraint conditions for the above mentioned joint configurations. The joint under pin loading was modeled by two dimensional finite element methods. Predicted net section strain concentrations were compared with experimental results

The nationality question in present-day Transcaucasia

Cover title"The remarks which follow represent not so much firm conclusions as suggestions and hypotheses derived from the study of generally unsatisfactory printed sources and rather inadequate personal observation."At head of title: Soviet Bloc Program"693"--handwritten on cove

Functional Outcomes of the Graduated Length Prosthetic Protocol for Bilateral Transfemoral Amputee Prosthetic Rehabilitation

The aim of this paper was to evaluate the functional outcomes of the Graduated Length Prosthetic Protocol (GLPP) in individuals with bilateral transfemoral amputations. The GLPP is a rehabilitation program designed to facilitate a successful transition to full-length prostheses, enhance independence, and improve functional outcomes for bilateral transfemoral amputees. This study utilized a prospective design to assess the effectiveness of the GLPP compared to traditional rehabilitation strategies. Literature was reviewed to determine the current limitations in research regarding bilateral transfemoral amputee prosthetic rehabilitation. The Concordia University St. Paul online library was utilized to obtain access to current published research. Studies included in the literature review were peer-reviewed and included case studies, survey-based studies, and gait comparisons between full-length and shortened bilateral transfemoral prosthesis users. Review of the available literature suggests that the use of shortened prostheses is an integral step in prosthetic rehabilitation for bilateral transfemoral amputees, however, further research needs to be conducted on the functional outcomes between those that do no begin their rehabilitation with shortened prostheses and how individuals functionally progress through a rehabilitation program such as the GLPP. The results of this study will contribute to the understanding of the functional outcomes of the GLPP. By comparing the GLPP group to the control group, the study aimed to determine whether the GLPP leads to improved functional outcomes in terms of mobility, balance, and ADLs. The findings will provide valuable insights for rehabilitation professionals and contribute to the development of evidence-based rehabilitation guidelines for individuals with bilateral transfemoral amputations

Research and Relationship-based Curriculum – Exploration of How Research and Relationship Experiences in Undergraduate Education Impact Students’ Employability, Graduate Education Intention, and Entrepreneurial Acumen

After decades of shrinking financial research support (Smith, 2004), continuously rising tuition and student debt (Beal et al., 2019), and the induction of numerous alternatives (Garrett, 2021), traditional higher education is struggling to provide the value that students are demanding (Woodall et al., 2014). Student engagement has been positively linked to increased retention (staying in school until completion of a degree) and reduced dropout (leaving school and not returning) rates (Finn & Rock, 1997; Reschly & Christenson, 2012), both of which contribute to how students perceive the value of higher education (Alves, 2011). The purpose of this study was to provide an original validation of a conceptual framework, Research and Relationship-Based Curriculum (RRBC), and explore the relationships between six RRBC independent variables derived from the National Survey on Student Engagement (NSSE) (The Trustees of Indiana University, 2020), i.e., High-Impact Practices (HIP), Reflective and Integrative Learning (RIL), Quality of Interactions (QI), Student-Faculty Interactions (SFI), Development of Transferable Skills (DTS), and Higher-Order Learning (HOL), and undergraduate students’ Graduate Education Intention as well as perceptions of their Employability and Entrepreneurial Acumen. Our key findings were that greater exposure to HIP and DTS increases students’ perceptions of Employability; that greater exposure to SFI increases students’ Graduate Education Intentions; and that greater DTS increases students’ perceptions of Entrepreneurial Acumen. These findings provide valuable implications for researchers and higher educational institutions

Nonlinear effects on composite laminate thermal expansion

Analyses of Graphite/Polyimide laminates shown that the thermomechanical strains cannot be separated into mechanical strain and free thermal expansion strain. Elastic properties and thermal expansion coefficients of unidirectional Graphite/Polyimide specimens were measured as a function of temperature to provide inputs for the analysis. The + or - 45 degrees symmetric Graphite/Polyimide laminates were tested to obtain free thermal expansion coefficients and thermal expansion coefficients under various uniaxial loads. The experimental results demonstrated the effects predicted by the analysis, namely dependence of thermal expansion coefficients on load, and anisotropy of thermal expansion under load. The significance of time dependence on thermal expansion was demonstrated by comparison of measured laminate free expansion coefficients with and without 15 day delay at intermediate temperature