Study of blade aspect ratio on a compressor front stage aerodynamic and mechanical design report

A single stage compressor was designed with the intent of demonstrating that, for a tip speed and hub-tip ratio typical of an advanced core compressor front stage, the use of low aspect ratio can permit high levels of blade loading to be achieved at an acceptable level of efficiency. The design pressure ratio is 1.8 at an adiabatic efficiency of 88.5 percent. Both rotor and stator have multiple-circular-arc airfoil sections. Variable IGV and stator vanes permit low speed matching adjustments. The design incorporates an inlet duct representative of an engine transition duct between fan and high pressure compressor

Towards a contextual approach to the place–homeless survival nexus: An exploratory case study of Los Angeles County

The characteristics of the immediate locale greatly affect the ability of homeless people to adapt to life on the street and in shelters, with different types of places nurturing different circumstances for survival. Current conceptualizations of the place–survival nexus are too narrow, relying on small-scale, intensive studies of particular places that are known to sustain homeless survival while ignoring more suburban and exurban locales, as well as failing to set these places of survival within the larger socio-economic spaces of the metropolitan area. Further, the literature is heavily qualitative, lacking any kind of ‘‘big picture” quantitative assessment of the nexus. In response, we contribute to the place–survival nexus literature by developing a typology of space for homeless survival and then use interview data to examine the variation in survival strategies across three types of urban space in Los Angeles County. Our results speak to how our innovative and exploratory approach enabled a broader, more extensive and variegated understanding of place–survival among homeless people than previous studie

Risk and Cost Assessment of Nitrate Contamination in Domestic Wells

This study combines empirical predictive and economics models to estimate the cost of remediation for domestic wells exceeding suggested treatment thresholds for nitrates. A multiple logistic regression model predicted the probability of well contamination by nitrate, and a life cycle costing methodology was used to estimate costs of nitrate contamination in groundwater in two areas of Nebraska. In south-central Nebraska, 37% of wells were estimated to be at risk of exceeding a threshold of 7.5 mg/L as N, and 17% were at risk of exceeding 10 mg/L as N, the legal limit for human consumption in the United States. In an area in northeastern Nebraska, 82% of wells were at risk of exceeding the 10 mg/L as N legal threshold. Reverse osmosis Point-of-Use (POU) treatment was the option with the lowest costs for a household (3–4 individuals), with an average of $4–$164 total regional cost per household per year depending on the threshold for treatment. Ion exchange and distillation were the next most cost-effective options. At the community level (~10,000 individuals), a reverse osmosis Point-of-Entry (POE) treatment system was the most expensive option for a community due to high initial costs and ongoing operation and maintenance costs, whereas the biological denitrification system was least expensive due to economies of scale. This study demonstrates integrated modeling methods to assess water treatment costs over time associated with groundwater nitrate contamination, including quantification of at-risk wells, and identifies suitable options for treatment systems for rural households and communities based on their cost

New Insights on Interstellar Gas-Phase Iron

In this paper, we report on the gas-phase abundance of singly-ionized iron (Fe II) for 51 lines of sight, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE). Fe II column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fitting those to a curve of growth. Our derivation of Fe II column densities and abundances creates the largest sample of iron abundances in moderately- to highly-reddened lines of sight explored with FUSE, lines of sight that are on average more reddened than lines of sight in previous Copernicus studies. We present three major results. First, we observe the well-established correlation between iron depletion and and also find trends between iron depletion and other line of sight parameters (e.g. f(H_2), E_(B-V), and A_V), and examine the significance of these trends. Of note, a few of our lines of sight probe larger densities than previously explored and we do not see significantly enhanced depletion effects. Second, we present two detections of an extremely weak Fe II line at 1901.773 A in the archival STIS spectra of two lines of sight (HD 24534 and HD 93222). We compare these detections to the column densities derived through FUSE spectra and comment on the line's f-value and utility for future studies of Fe II. Lastly, we present strong anecdotal evidence that the Fe II f-values derived empirically through FUSE data are more accurate than previous values that have been theoretically calculated, with the probable exception of f_1112.Comment: Accepted for publication in ApJ, 669, 378; see ApJ version for small updates. 53 total pages (preprint format), 7 tables, 11 figure

Rotational CARS application to simultaneous and multiple-point temperature and concentration determination in a turbulent flow

Coherent anti-Stokes Raman scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous (approximately 10 ns) rotational temperature of N2 gas at room temperature and below with good spatial resolution (0.2 x 0.2 x 3.0 cu mm). A broad bandwidth dye laser is used to obtain the entire rotational spectrum from a single laser pulse; the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296 K, and over the pressure range of .13 to 15.3 atm

Review of \u3ci\u3eThe Red Corner: The Rise and Fall of Communism in Northeastern Montana\u3c/i\u3e by Verlaine Stoner McDonald

It\u27s not often that such names as Stalin, Lenin, and Trotsky figure centrally in works dealing with Montana history. But that\u27s the case with Verlaine Stoner McDonald\u27s The Red Corner: The Rise and Fall of Communism in Northeastern Montana. McDonald\u27s history deals with a little-known but fascinating chapter in Montana, and western, history the 1920s electoral takeover of the local government of Sheridan County, Montana, by Communist Party members. As McDonald shows, Sheridan County, an agrarian territory of 10,000 persons in the extreme northeastern corner of the state, proved fertile territory for a variety of leftist political movements, including Bryanite populism, the Non-Partisan League, and, for a brief period, Communism

A Comparison of Qualities Desired in Academic Teachers, Physical Education Teachers, and Athletic Coaches in the Senior High Schools of Utah

The state has ordered the establishment of schools for the education of all the children in the state. Each child is entitled to as thorough an education as the community can afford, and this education can be attained only when the teachers selected are the best possible to obtain with the money available