Digital-flutter-suppression-system investigations for the active flexible wing wind-tunnel model

Active flutter suppression control laws were designed, implemented, and tested on an aeroelastically-scaled wind tunnel model in the NASA Langley Transonic Dynamics Tunnel. One of the control laws was successful in stabilizing the model while the dynamic pressure was increased to 24 percent greater than the measured open-loop flutter boundary. Other accomplishments included the design, implementation, and successful operation of a one-of-a-kind digital controller, the design and use of two simulation methods to support the project, and the development and successful use of a methodology for on-line controller performance evaluation

Aeroservoelastic wind-tunnel investigations using the Active Flexible Wing Model: Status and recent accomplishments

The status of the joint NASA/Rockwell Active Flexible Wing Wind-Tunnel Test Program is described. The objectives are to develop and validate the analysis, design, and test methodologies required to apply multifunction active control technology for improving aircraft performance and stability. Major tasks include designing digital multi-input/multi-output flutter-suppression and rolling-maneuver-load alleviation concepts for a flexible full-span wind-tunnel model, obtaining an experimental data base for the basic model and each control concept and providing comparisons between experimental and analytical results to validate the methodologies. The opportunity is provided to improve real-time simulation techniques and to gain practical experience with digital control law implementation procedures

Factors Associated with Atypical Moles in New Hampshire, USA

Only a few studies, conducted in Sweden, assessed factors associated with the presence of atypical moles in the general population. We conducted a population-based, case-control study in New Hampshire, USA, to identify factors associated with atypical moles. In our study, atypical moles affected 14% of the study population. The adjusted odds ratio (OR) was 0.34 (95% confidence interval (CI)=0.14-0.80) for those with the highest adulthood recreational sun exposure, relative to the lowest. The OR for any freckles, compared to none, was 2.24 (95% CI=1.18-4.25). We found a linear relationship between the number of benign moles and the presence of atypical moles (p for trend=0.0001). The OR was 7.34 (95% CI=3.03-17.80) for \u3e15 benign moles, relative to 0-4. Our data indicate that freckles and benign moles, which may reflect melanocytic inducibility, are strongly associated with atypical moles. The inverse association with sun exposure should be considered with caution

Rationale and Methods for Archival Sampling and Analysis of Atmospheric Trace Chemical Contaminants On Board Mir and Recommendations for the International Space Station

Collection and analysis of spacecraft cabin air samples are necessary to assess the cabin air quality with respect to crew health. Both toxicology and engineering disciplines work together to achieve an acceptably clean cabin atmosphere. Toxicology is concerned with limiting the risk to crew health from chemical sources, setting exposure limits, and analyzing air samples to determine how well these limits are met. Engineering provides the means for minimizing the contribution of the various contaminant generating sources by providing active contamination control equipment on board spacecraft and adhering to a rigorous material selection and control program during the design and construction of the spacecraft. A review of the rationale and objectives for sampling spacecraft cabin atmospheres is provided. The presently-available sampling equipment and methods are reviewed along with the analytical chemistry methods employed to determine trace contaminant concentrations. These methods are compared and assessed with respect to actual cabin air quality monitoring needs. Recommendations are presented with respect to the basic sampling program necessary to ensure an acceptably clean spacecraft cabin atmosphere. Also, rationale and recommendations for expanding the scope of the basic monitoring program are discussed

New Horizons: Understanding the Processes and Practices of Youth Development

Abstract: This article presents new horizon for research on youth development by focusing on the challenges youth face in learning teamwork and in coming to terms with diversity. These are both essential competencies for navigating the "real world" of the 21 st century. We examine how youth experience these challenges within programs; also how they present second-order challenges to practitioners. The underlying message of this article is that it is essential for researchers to see programs from the point of view of the people in them. Researchers have learned quite a bit of what can be learned from arm's length: that programs can make a difference in youths' lives and that certain features of settings are associated with these changes. To go further, researchers need to work side-by-side with practitioners and youth to understand their complex worlds as they experience them

New Horizons: Understanding the Processes and Practices of Youth Development

This article presents new horizons for research on youth development by focusing on the challenges youth face in learning teamwork and in coming to terms with diversity. These are both essential competencies for navigating the “real world” of the 21st century. We examine how youth experience these challenges within programs; also how they present second-order challenges to practitioners. The underlying message of this article is that it is essential for researchers to see programs from the point of view of the people in them. Researchers have learned quite a bit of what can be learned from arm’s length: that programs can make a difference in youths’ lives and that certain features of settings are associated with these changes. To go further, researchers need to work side-by-side with practitioners and youth to understand their complex worlds as they experience them

Geographical and climatic limits of needle types of one- and two-needled pinyon pines

Aim The geographical extent and climatic tolerances of one- and two-needled pinyon pines (Pinus subsect. Cembroides) are the focus of questions in taxonomy, palaeoclimatology and modelling of future distributions. The identification of these pines, traditionally classified by one- versus two-needled fascicles, is complicated by populations with both one- and two-needled fascicles on the same tree, and the description of two more recently described one-needled varieties: the fallax-type and californiarum-type. Because previous studies have suggested correlations between needle anatomy and climate, including anatomical plasticity reflecting annual precipitation, we approached this study at the level of the anatomy of individual pine needles rather than species. Location Western North America. Methods We synthesized available and new data from field and herbarium collections of needles to compile maps of their current distributions across western North America. Annual frequencies of needle types were compared with local precipitation histories for some stands. Historical North American climates were modeled on a c. 1-km grid using monthly temperature and precipitation values. A geospatial model (ClimLim), which analyses the effect of climate modulated physiological and ecosystem processes, was used to rank the importance of seasonal climate variables in limiting the distributions of anatomical needle types. Results The pinyon needles were classified into four distinct types based upon the number of needles per fascicle, needle thickness and the number of stomatal rows and resin canals. The individual needles fit well into four categories of needle types, whereas some trees exhibit a mixture of two needle types. Trees from central Arizona containing a mixture of Pinus edulis and fallax-type needles increased their percentage of fallax-type needles following dry years. All four needle types occupy broader geographical regions with distinctive precipitation regimes. Pinus monophylla and californiarum-type needles occur in regions with high winter precipitation. Pinus edulis and fallax-type needles are found in regions with high monsoon precipitation. Areas supporting californiarum-type and fallax-type needle distributions are additionally characterized by a more extreme May–June drought. Main conclusions These pinyon needle types seem to reflect the amount and seasonality of precipitation. The single needle fascicle characterizing the fallax type may be an adaptation to early summer or periodic drought, while the single needle of Pinus monophylla may be an adaptation to summer–autumn drought. Although the needles fit into four distinct categories, the parent trees are sometimes less easily classified, especially near their ancestral Pleistocene ranges in the Mojave and northern Sonoran deserts. The abundance of trees with both one- and two-needled fascicles in the zones between P. monophylla, P. edulis and fallax-type populations suggest that needle fascicle number is an unreliable characteristic for species classification. Disregarding needle fascicle number, the fallax-type needles are nearly identical to P. edulis, supporting Little’s (1968) initial classification of these trees as P. edulis var. fallax, while the californiarum-type needles have a distinctive morphology supporting Bailey’s (1987) classification of this tree as Pinus californiarum