Experimental dynamic stiffness and damping of externally pressurized gas-lubricated journal bearings

A rigid vertical shaft was operated with known amounts of unbalance at speeds to 30,000 rpm and gas supply pressure ratios to 4.8. From measured amplitude and phase angle data, dynamic stiffness and damping coefficients of the bearings were determined. The measured stiffness was proportional to the supply pressure, while damping was little affected by supply pressure. Damping dropped rapidly as the fractional frequency whirl threshold was approached. A small-eccentricity analysis overpredicted the stiffness by 20 to 70 percent. Predicted damping was lower than measured at low speeds but higher at high speeds

Analysis of intrapulse chirp in CO2 oscillators

Pulsed single-frequency CO2 laser oscillators are often used as transmitters for coherent lidar applications. These oscillators suffer from intrapulse chirp, or dynamic frequency shifting. If excessive, such chirp can limit the signal-to-noise ratio of the lidar (by generating excess bandwidth), or limit the velocity resolution if the lidar is of the Doppler type. This paper describes a detailed numerical model that considers all known sources of intrapulse chirp. Some typical predictions of the model are shown, and simple design rules to minimize chirp are proposed

Use of ERTS-1 data in the educational and applied research programs of agricultural extension

There are no author-identified significant results in this report

Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California

There are no author-identified significant results in this report

The longitudinal negative impact of early stressful events on emotional and physical well-being: The buffering role of cardiac vagal development

Early stressful events negatively affect emotional and physical well-being. Cardiac vagal tone (CVT), which is associated with better emotional and physical well-being, usually gradually increase in early childhood. Nonetheless, children's CVT developmental trajectories are greatly variable, such that CVT can increase or decrease across the years. The present study examines the longitudinal effects of early stressful events and the role of 4 years CVT developmental trajectory on children's emotional and physical well-being. Forty-two 4-year-old children were enrolled. Number of stressful events and resting electrocardiogram (ECG) were collected at T1. ECG was registered again after one (T2), two (T3) and three (T4) years. Children's emotional and physical well-being were assessed at T4 through the Child Health and Illness Profile – Child Edition (CHIP–CE). CVT development was calculated as the angular coefficient, reflecting the developmental trajectory of CVT across the four timepoints. Results yielded that higher experienced stressful events predicted poorer emotional and physical well-being after 4 years. The interaction between the number of stressful events and CVT development emerged on physical well-being. Early stressful events negatively affect long-term children's emotional and physical well-being while a positive CVT development seems to mitigate the negative effects of early stressful events on physical well-being

Paper Session II-B - 3-Dimensional Feature Mapping Using Spatial Spectral Analysis

Orbiter vehicles are routinely exposed to a variety of small scale debris while operating in low earth orbit. Impacts with such debris often result in surface and/or subsurface damage to orbiter windows. Current procedures require windows to be manually inspected for impact damage after each shuttle mission. Once identified, surface damage feature depths are determined by analyzing mold impressions of the damaged areas. Subsurface damage always results in window rejection since the depths of subsurface features are deemed unmeasurable using standard mold impression measurement techniques. This paper presents an automated optical technique for measuring the depth of small scale surface and subsurface damage features in orbiter windows. Test results based on actual orbiter window damage features are also presented

Viewing Nature Scenes Positively Affects Recovery of Autonomic Function Following Acute-Mental Stress

A randomized crossover study explored whether viewing different scenes prior to a stressor altered autonomic function during the recovery from the stressor. The two scenes were (a) nature (composed of trees, grass, fields) or (b) built (composed of man-made, urban scenes lacking natural characteristics) environments. Autonomic function was assessed using noninvasive techniques of heart rate variability; in particular, time domain analyses evaluated parasympathetic activity, using root-mean-square of successive differences (RMSSD). During stress, secondary cardiovascular markers (heart rate, systolic and diastolic blood pressure) showed significant increases from baseline which did not differ between the two viewing conditions. Parasympathetic activity, however, was significantly higher in recovery following the stressor in the viewing scenes of nature condition compared to viewing scenes depicting built environments (RMSSD; 50.0 ± 31.3 vs 34.8 ± 14.8 ms). Thus, viewing nature scenes prior to a stressor alters autonomic activity in the recovery period. The secondary aim was to examine autonomic function during viewing of the two scenes. Standard deviation of R-R intervals (SDRR), as change from baseline, during the first 5 min of viewing nature scenes was greater than during built scenes. Overall, this suggests that nature can elicit improvements in the recovery process following a stressor. © 2013 American Chemical Society

Hydrodynamical Simulations of the Lyman Alpha Forest: Model Comparisons

We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological parameters. Focusing on the redshift range from two to four, we show that: (1) most of the evolution in the distributions of optical depth, flux and column density can be understood by simple scaling relations, (2) the shape of optical depth distribution is a sensitive probe of the amplitude of density fluctuations on scales of a few hundred kpc, (3) the mean of the b distribution (a measure of the width of the absorption lines) is also very sensitive to fluctuations on these scales, and decreases as they increase. We perform a preliminary comparison to observations, where available. A number of other properties are also examined, including the evolution in the number of lines, the two-point flux distribution and the HeII opacity.Comment: 37 pages, 21 figures, submitted to Ap