Swirl-can combustor segment

Combustor produces uniform circumferential and radial combustor exit temperature profiles and high combustion efficiency at high temperature loads. Absence of diluent air entry ports eliminates stress concentration points, low pressure fuel alleviates nozzle fouling, and abundant air at all burning stages reduces smoke

Conjugate points on extremal rocket paths

Existence of conjugate points on extreme rocket flight paths in trajectory optimization analysi

Ecologic Relationships Between Bacteria and Algae in Mass Culture

Ecological relationships between bacteria and algae in mass cultur

Ultrafast magnetophotoconductivity of semi-insulating gallium arsenide

The speed of opto-electronic switches is increased or decreased by the application of a magnetic field. This is achieved by inducing a carrier drift toward or away from the semiconductor surface, resulting in the enhancement or suppression of surface recombination. We establish that surface recombination plays a major role in determining the speed of the opto-electronic switch

Attention and Emotion Regulation in Social Functioning

Recent models of social functioning have identified attention and emotion regulation as important factors in explaining social functioning. In these models, emotion regulation is conceptualized as a cognitive process under attention control (Beauchamp & Anderson, 2010; Crick & Dodge, 1994; Lemerise & Arsenio, 2000). Recently, an alternate conceptualization of emotion regulation has been suggested. In this model, emotion regulation is independent of attentional control and is conceptualized as consisting of four factors: emotion awareness and understanding; acceptance; impulse control and goal directed behavior in the context of negative emotions; and flexible use of contextually appropriate strategies to modulate emotion responses in goal-directed actions (Gratz & Roemer, 2004). Emerging evidence has linked attention and emotion regulation problems (Wehmeier, Schacht, & Barkley, 2010) and emotion regulation and social functioning (Wilkowski, Robinson, Gordon, & Troop-Gordon, 2007). However, it has been observed that not all individuals with clinically significant attention problems have clinically significant emotion regulation problems (Biederman, Petty, et al., 2012; Wehmeier et al., 2010). It therefore appears reasonable to consider the contribution of each of these processes to social functioning independently. In order to examine the relationship of emotion and attention regulation to each other and to social functioning, participants (n=103) 18 years of age or older enrolled at a public university were asked to complete online self-reports of attentional, emotional, and social functioning and a demographic questionnaire. Hierarchical regression was performed and results revealed significant, independent contribution of attention and emotion regulation to explaining variability in social functioning. Analyses based on WHOQOL100 measures suggested that attention regulation accounts for significant variability in social functioning after demographic factors have been explained, and that emotion regulation accounts for significant variability in social functioning after accounting for attention. A significant interaction between attention and emotion regulation was also found. Specifically, the interaction of Sum Inattention and Nonacceptance of Emotional Responses was significant for three of the four dependent variables and approached significance for the fourth. These findings highlight the importance of understanding the relationship between attention and emotional regulation in social functioning

Comet Shoemaker‐Levy 9: No effect on the Io plasma torus

Observations of the Io plasma torus made before, during, and after the impact of Comet Shoemaker‐Levy 9 with Jupiter reveal no comet‐induced changes. Three weeks of high spectral‐resolution ground‐based visible spectroscopy show no changes larger than typical day‐to‐day variations in the torus densities, ion temperatures, or rotation velocities. Comparison with six months of identically obtained data from 1991 and 1992 also shows no differences

Effects of Ultra-Clean and centrifugal filtration on rolling-element bearing life

Fatigue tests were conducted on groups of 65-millimeter bore diameter deep-groove ball bearings in a MIL-L-23699 lubricant under two levels of filtration. In one test series, the oil cleanliness was maintained at an exceptionally high level (better than a class "000" per NAS 1638) with a 3 micron absolute barrier filter. These tests were intended to determine the "upper limit" in bearing life under the strictest possible lubricant cleanliness conditions. In the tests using a centrifugal oil filter, contaminants of the type found in aircraft engine filters were injected into the filters' supply line at 125 milligrams per bearing-hour. "Ultra-clean" lubrication produced bearing fatigue lives that were approximately twice that obtained in previous tests with contaminated oil using 3 micron absolute filtration and approximately three times that obtained with 49 micron filtration. It was also observed that the centrifugal oil filter had approximately the same effectiveness as a 30 micron absolute filter in preventing bearing surface damage

Control of large space structures

The control of large space structures was studied to determine what, if any, limitations are imposed on the size of spacecraft which may be controlled using current control system design technology. Using a typical structure in the 35 to 70 meter size category, a control system design that used actuators that are currently available was designed. The amount of control power required to maintain the vehicle in a stabilized gravity gradient pointing orientation that also damped various structural motions was determined. The moment of inertia and mass properties of this structure were varied to verify that stability and performance were maintained. The study concludes that the structure's size is required to change by at least a factor of two before any stability problems arise. The stability margin that is lost is due to the scaling of the gravity gradient torques (the rigid body control) and as such can easily be corrected by changing the control gains associated with the rigid body control. A secondary conclusion from the study is that the control design that accommodates the structural motions (to damp them) is a little more sensitive than the design that works on attitude control of the rigid body only

Effect of filtration on rolling-element-bearing life in contaminated lubricant environment

Fatigue tests were conducted on groups of 65 millimeter-bore ball bearings under four levels of filtration with and without a contaminated MIL-L-23699 lubricant. The baseline series used noncontaminated oil with 49 micron absolute filtration. In the remaining tests contaminants of the composition found in aircraft engine filters were injected into the filter's supply line at a constant rate of 125 milligrams per bearing-hour. The test filters had absolute particle removal ratings of 3, 30, 49, and 105 microns (0.45, 10, 30, and 70 microns nominal), respectively. Bearings were tested at 15,000 rpm under 4580 newtons radial load. Bearing life and running tract condition generally improved with finer filtration. The 3 and 30 micron filter bearings in a contaminated lubricant had statistically equivalent lives, approaching those from the baseline tests. The experimental lives of 49 micron bearings were approximately half the baseline bearing's lives. Bearings tested with the 105 micron filter experienced wear failures. The degree of surface distress, weight loss, and probable failure mode were found to be dependent on filtration level, with finer filtration being clearly beneficial

Nitrogen Management for Teff Hay Production

Fertilization of teff with nitrogen (N) resulted in increased forage production, but amounts above 25 lb/a did not often increase yields in this study. Urea as the N source produced at least as much yield response as the alternate, an extended source of nitrogen (ESN)