A 3-component laser-Doppler velocimeter data acquisition and reduction system

A laser doppler velocimeter capable of measuring all three components of velocity simultaneously in low-speed flows is described. All the mean velocities, Reynolds stresses, and higher-order products can be evaluated. The approach followed is to split one of the two colors used in a 2-D system, thus creating a third set of beams which is then focused in the flow from an off-axis direction. The third velocity component is computed from the known geometry of the system. The laser optical hardware and the data acquisition electronics are described in detail. In addition, full operating procedures and listings of the software (written in BASIC and ASSEMBLY languages) are also included. Some typical measurements obtained with this system in a vortex/mixing layer interaction are presented and compared directly to those obtained with a cross-wire system

Verification of performance results for a low-speed 15 percent elliptical circulation control airfoil

Low-speed wind tunnel tests performed by the Naval Ship Research and Development Center (NSRDC) on a circulation control airfoil model was repeated by the Joint Institute for Aerodynamics and Acoustics in an attempt to reproduce the performance results. The model used was a 15% ellipse with interchangeable trailing edges. Surface pressure measurements were taken to obtain lift and pitching moment coefficients as functions of jet blowing momentum, and the momentum deficit in the wake was measured and used to calculate the drag coefficient. The effects of spanwise slot height variation and of leading edge blowing on performance were also investigated. The performance results showed that of the three slot heights tested, a slot height/chord ratio of 0.0022 produced the most lift coefficient for a given blowing rate. Lift obtained in the current test ranged from 2 to 35% lower than the NSRDC test. However, the two data sets compared reasonably well considering wind tunnel and wall blowing scheme differences. The spanwise lift distribution showed less change in lift due to a variation in slot height than expected. The leading edge blowing results demonstrated that although lift initially decreased, a positive lift increment was possible at higher leading edge blowing rates

Forest Cover Change and Post-Fire Response In The Southern Rocky Mountains

Forests are some of the Earth&rsquo;s most important ecosystems. They are sanctums of biodiversity, play a key role in nutrient cycling, and provide countless ecosystem services to humans. Recent studies have identified broad-scale changes in forest cover across the globe. A richer understanding of these changes can be developed by identifying specific causal mechanisms, placing recent shifts in forest cover in a historical context, and by using knowledge of the past and present to make inferences about the future. The goal of our research was to better understand the past, present, and future of forested ecosystems in the northern Front Range of Colorado (NFR) and in the Southern Rocky Mountains Ecoregion (SRME). In particular, this dissertation focused on the roles of historical land use, wildfire activity, and post-fire recovery in observed and projected changes in conifer forests. To quantify the extent to which forest cover in the NFR changed 1938-2015 and to provide insight into possible potential drivers, we used high-resolution historical (c. 1938) and contemporary (2015) aerial photography to classify forested area across a 2932 km2 study area. We found that historical patterns of land use, as well as historical and contemporary fire activity and subsequent post-fire recovery, played key roles in 20th-century changes in forest cover across the NFR. To better characterize the drivers of limited conifer recovery in low-elevation forests, we surveyed post-fire conifer seedling abundance, tree establishment, and seed cone production across 15 wildfires in southern Colorado and northern New Mexico. We then used these data to quantify potential bottlenecks to post-fire conifer recovery. Lastly, we combined these data with similar surveys in the SRME performed by three former graduate students in Colorado and Arizona. Using the combined dataset, we modeled the extent to which a warming climate is limiting post-fire recovery of two widespread conifer species and projected that further declines in resilience are likely through 2100. Our findings reinforce the historical importance of wildfire, anthropogenic impacts, and abiotic factors in the dynamics of forested landscapes in the southern Rocky Mountains. These same factors will remain important throughout the upcoming century.</p

Jordan Forms of Real and Complex Matrices Under Rank One Perturbations

New perturbation results for the behavior of eigenvalues and Jordan forms of real and complex matrices under generic rank one perturbations are discussed. Several results that are available in the complex case are proved as well for the real case and the assumptions on the genericity are weakened. Rank one perturbations that lead to maximal algebraic multiplicities of the new eigenvalues are also discussed

The Use of 2,4-Dinitrophenylhydrazine Derivatives of Ovarian Ketosteroids in Steroid Analysis

This paper reports the development of a technically simple analytical technique for the characterization and quantitative determination of ovarian ketosteroids employing derivative formation with 2,4-dinitrophenylhydrazine (2,4-DNP), separation by thin-layer chromatography (TLC), and quantitative determination by spectrophotometry. The chemical identities of the derivatives were established by nitrogen analysis. The melting point, chromatographic mobilities of the free steroids and their derivatives on silica gel G in three systems, wavelength of maximum absorption in chloroform and ethanol, and molar absorption coefficient are reported for the 2,4-DNP derivatives of ovarian ketosteroids. The relationship between the absorption maximum in chloroform and the chemical structure of the derivatives has been analyzed

wildfire activity and land use drove 20th century changes in forest cover in the colorado front range

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Multiple Captures of White-footed Mice (Peromyscus leucopus): Evidence for Social Structure?

Multiple captures (34 double, 6 triple) in standard Sherman live traps accounted for 6.3% of 1355 captures of Peromyscus leucopus (white-footed mice) in forested habitat in southern Illinois, from Oct. 2004 through Oct. 2005. There was a significant positive relationship between both the number and the proportion of multiple captures and estimated monthly population size. Multiple captures were all intraspecific and occurred significantly more often from Nov. through Mar. when animals were not reproductively active, but this was confounded by seasonal changes in abundance. Age/gender distribution of animals in double captures did not differ from that expected from random pairing. We suggest that sociality and synchronous entry of two white-footed mice into traps were the primary determinants of double captures; sensitivity of traps may have been the primary factor in triple capture

The impact of speaking style on speech recognition in quiet and multi-talker babble in adult cochlear implant users

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