Simplified thermal estimation techniques for large space structures

A tool for making rapid estimates of the response of space structures to thermal environments encountered in earth orbits is provided for the designer of these structures. Charts giving heating rates and temperatures for certain typical large spacecraft structural elements are provided. Background information for spacecraft thermal design considerations is presented. Environments, requirements, thermal control techniques, design guidelines, and approaches available for more detailed thermal response analysis are discussed

Does marketing and sales integration always pay off? evidence from a social capital perspective

Building on social capital theory, the authors view the marketing and sales interface as a set of inter-group ties and investigate how firms (1) generate value from inter-group relationships and (2) develop the social capital embedded in these relationships. Their findings suggest that social capital enhances, but can also limit, a firm’s performance depending on the characteristics of its customers. Their results also demonstrate that managing the marketing and sales interface at different levels of customer concentration is critical to the success of a firm’s performance.Marketing organization; sales organization; interface; social capital theory.

Accuracy of atomic positions in the zunyite structure

The accuracy of positional parameters in the refined zunyite structure is estimated by four different statistical methods, including a comparison of two entirely independent refinements of the structure. The estimates show tolerable agreement, but disagree as to the importance of F_o measurement error in affecting the parameter error. Reliable estimates of ± 0.008 Å (standard deviation) for oxygen coordinates and ± 0.003 Å for silicon and aluminum coordinates are obtained

The crystal structure of zunyite

The structure proposed by Pauling for the rare aluminosilicate mineral zunyite (Al_(13)(OH)_(18)Si_5O_(20)Cl) has been confirmed and refined with the use of 163 hkO reflections and 409 hhl reflections obtained with Mo Kα radiation from single crystal Weissenberg photographs. The structure is isometric (T^2_d) and is built up of Si_5O_(16) groups of linked silicon tetrahedra combined with Al_(12)O_(16)(OH)_(30) groups of linked aluminum octahedra. Refinement is carried out independently for the hkO and hhl data, and the final reliability factors are 0·12 for both sets of data. Positional parameters are refined by the least-squares method, and isotropic temperature parameters for separate atoms are adjusted with the help of difference syntheses. The refined structure differs from the trial structure by distortion of coordination polyhedra in a fashion similar to the distortions in related structures. The interatomic distance Al-O of 1·80 ± 0·016 Å is derived for tetrahedrally coordinated aluminum. The averaged Si-O distance is 1·64 ± 0·01 Å. The arrangement of protons in the structure is deduced from structural arguments. The proposed arrangement requires the inclusion of at least two fluorine atoms per stoichiometric molecule, modifying the chemical formula to (OH, F)_(16)F_2Al_(13)Si_5O_(20)Cl and explaining the importance of fluorine in the formation of zunyite

On the debt Capacityof growth Options

If debt capacity is defined as the incremental debt that is optimally associated with an additional asset, then the debt capacity of growth options is negative. Underinvestment costs of debt increase and free cash flow benefits of debt fall with additional growth options. Thus, if firm value increases with additional growth options, then leverage not only declines, but the firm’s optimal total debt level declines as well. This result implies a negative relation between book leverage and growth options and provides a new economic interpretation of book leverage regressions.Growth options; Book leverage

The Impact of Team-Based Learning’s Readiness Assurance Process on Virtually Isolated Adults

The purpose of this study was to test the effectiveness of the readiness assurance process of team-based learning (TBL) in virtually isolated settings. Many Internet sites offer courses for adults to use on their own without access to mentors or other learners. However, educational theory suggests that people learn better with others than by themselves. The focus of this investigation was whether the inclusion of the readiness assurance process would increase participants’ levels of learning based on Bloom’s revised taxonomy within the limits of virtual isolation. In this study an experimental pretest-posttest design was employed. Using a 2- day mini-course about listening in marriage, 117 participants were randomly assigned to three groups. In the TBL group, married couples worked together following the principles of the readiness assurance process. In the independent group, one spouse from a marriage worked alone, also following the principles of the readiness assurance process. In the baseline group, one spouse from a marriage took the pretest and posttest only. The first posttest, called posttest-L, measured lower levels of learning (remembering and understanding). The second posttest, called posttest-D, measured deeper learning (applying and evaluating). Using ANCOVA with the pretests as the covariates, results showed a statistically significant difference in learning gains between the TBL group and the independent group for lower levels of learning (ES = .39). However, statistical significance was not achieved for deeper learning. Moreover, TBL scores and independent scores were no different from the baseline scores for measures of deeper learning. Along with explanations for these results, limitations of the study are described and suggestions for future research are offered

Electro-silver plating. Part I. Early technical history. Part II. The Author's investigation

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Structural/thermal considerations for design of large space platform structures

A method is described for placing a large, STS-compatible platform on orbit utilizing a construction method employing both deployable and erectable structures. A multifunctional mechanism is used for deployable structures and an on-orbit assembly is used for erectable structures. Also analyses are discussed which assess the thermal distortion of a simple open truss and a more complex truss

Lightweight Vacuum Jacket for Cryogenic Insulation - Appendices to Final Report

The feasibility is demonstrated of producing a lightweight vacuum jacket using state-of-the-art technology and materials. Design and analytical studies were made on an orbital maneuvering system fuel tank. Preliminary design details were completed for the tank assembly which included an optimized vacuum jacket and multilayered insulation system. A half-scale LH2 test model was designed and fabricated and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of 0.00001 was measured, approximately 1500 hours of vacuum pressure was sustained, and 29 vacuum pressure cycles were experienced prior to failure. For vol. 1, see N75-26192