Spacecraft Systems Working Group report

Issues addressed include: definition of user/commercial/government needs by function; criteria for prioritization of needs; overall criteria for technology assessment; system configuration drivers (key trade studies); space infrastructure interface; and cost drivers (pros and cons of standardization, manufacturing, test, serviceability, and supportability)

The Reactivity of MgB2 with Common Substrate and Electronic Materials

The reactivity of MgB2 with powdered forms of common substrate and electronic materials is reported. Reaction temperatures between 600 C and 800 C, encompassing the range commonly employed in thin-film fabrication, were studied. The materials tested for reactivity were ZrO2, yttria stabilized zirconia (YSZ), MgO, Al2O3, SiO2, SrTiO3, TiN, TaN, AlN, Si, and SiC. At 600 C, MgB2 reacted only with SiO2 and Si. At 800 C, however, reactions were observed for MgB2 with Al2O3, SiO2, Si, SiC, and SrTiO3. The Tc of MgB2 decreased in the reactions with SiC and Al2O3.Comment: 5 figure

Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS): A conceptual framework

In recent years there has been increasing interest in applying the computer based problem solving techniques of Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS) to analyze extremely complex problems. A conceptual framework is developed for successfully integrating these three techniques. First, the fields of AI, OR, and DSS are defined and the relationships among the three fields are explored. Next, a comprehensive adaptive design methodology for AI and OR modeling within the context of a DSS is described. These observations are made: (1) the solution of extremely complex knowledge problems with ill-defined, changing requirements can benefit greatly from the use of the adaptive design process, (2) the field of DSS provides the focus on the decision making process essential for tailoring solutions to these complex problems, (3) the characteristics of AI, OR, and DSS tools appears to be converging rapidly, and (4) there is a growing need for an interdisciplinary AI/OR/DSS education

Making Streets into Complete Streets

Researchers created a manual to aid planners in adopting complete streets policies and designs

An approach to CMG steering using feedback linearization

This paper presents an approach for controlling spacecraft equipped with control moment gyroscopes. A technique from feedback linearization theory is used to transform the original nonlinear problem to an equivalent linear form without approximating assumptions. In this form, the spacecraft dynamics appear linearly, and are decoupled from redundancy in the system of gyroscopes. A general approach to distributing control effort among the available actuators is described which includes provisions for redistribution of rotors, explicit bounds in gimbal rates, and guaranteed operation at or near singular configurations. A particular algorithm is developed for systems of double-gimbal devices, and demonstrated in two examples for which existing approaches fail to give adequate performance

Statistical Analysis of Yeast Nutrient in Hard Cider Brewing

  In brewing, it is widely known that trace elements, particularly zinc, are required by yeast in order to grow and ferment. The most sensitive and time-consuming step of cider production is the fermentation process, and problems encountered during this process can lead to prolonged fermentation time and the deterioration of cider quality. Several studies have been published on the optimal zinc concentration to increase the rate of fermentation, but few have studied this process in quantities that are practical to the average homebrewer. Furthermore, homebrewers more commonly supplement with yeast nutrient rather than zinc, as yeast nutrient is more widely available and easier to use. Given that the use of zinc in increasing fermentation rate has been so widely studied, it may be useful for homebrewers to know if zinc is as useful in increasing fermentation rate on a smaller scale. In this study, we explore different methods of increasing fermentation rate by supplementing with various levels of zinc and yeast nutrient, as well as a combination of zinc and yeast nutrient. We present statistical models that describe specific gravity as a function of time, identify underlying causes of variability in specific gravity, and determine if supplementing with zinc is an effective method of increasing fermentation rate on a smaller scale. The results of this study show that supplementing with the full recommended amount of yeast nutrient is the most effective method of increasing fermentation rate, while the other treatment levels were not significantly different from the control treatment

Weight optimization of an aerobrake structural concept for a lunar transfer vehicle

An aerobrake structural concept for a lunar transfer vehicle was weight optimized through the use of the Taguchi design method, finite element analyses, and element sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter-depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The aerobrake structural configuration with the minimum weight was 44 percent less than the average weight of all the remaining satisfactory experimental configurations. In addition, the results of this study have served to bolster the advocacy of the Taguchi method for aerospace vehicle design. Both reduced analysis time and an optimized design demonstrated the applicability of the Taguchi method to aerospace vehicle design

Restrictions on the Production and Interstate Distribution of Margarine in the Eleven Western States

This item is part of the Agricultural Experiment Station archive. It was digitized from a physical copy provided by the University Libraries at the University of Arizona. For more information, please email CALS Publications at [email protected]