Life and reliability of rotating disks

In aerospace applications, an engineer must be especially cognizant of size and weight constraints which affect design decisions. Although designing at or below the material fatigue limit may be desirable in most industrial applications, in aerospace application it is almost mandatory to design certain components for a finite life at an acceptable probability of survival. Zaretsky outlined such a methodology based in part on the work of W. Weibull (1939, 1951) and G. Lundberg and A. Palmgren (1947a, 1947b, 1952). It is the objective of this work to apply the method of Zaretsky (1987) to statistically predict the life of a generic solid disk with and without bolt holes; determine the effect of disk design variables, thermal loads, and speed on relative life; and develop a generalized equation for determining disk life by incorporating only these variables

Localization of aeroelastic modes in mistuned high-energy turbines

The effects of blade mistuning on the aerodynamic characteristics of a class of bladed-disk assemblies, namely high energy turbines, are discussed. The specific rotor analyzed is the first stage of turbine blades of the oxidizer turbopump in the Space Shuttle Main Engine. The common occurrence of fatigue cracks for these turbine blades indicates the possibility of high dynamic loading. Since mistuning under conditions of weak interblade coupling has been shown to increase blade response amplitudes drastically for simple structural models of blade assemblies, it provides a plausible explanation for the occurrence of cracks. The focus here is on the effects of frequency mistuning on the aeroelastic stability of the assembly and on the aeroelastic mode shapes

Migration Creation, Diversion, and Retention: New Deal Grants and Migration: 1935-1940

During the 1930s the federal government embarked upon an ambitious series of grant programs designed to counteract the Great Depression. The amounts distributed varied widely across the country and potentially contributed to population shifts. We estimate an aggregate discrete choice model, in which household heads choose among 466 economic subregions. The structural model allows us to decompose the effects of program spending on migration into three categories: the effect of spending on keeping households in their origin (retention), the effect of pulling non-migrants out of their origin (creation), and the effect of causing migrants to substitute away from an alternative destination (diversion). An additional dollar of public works and relief spending increased net migration into an area primarily by retaining the existing population and creating new migration into the county. Only a small share of the increase in net migration rate was caused by diversion of people who had already chosen to migrate. AAA spending contributed to net out migration, primarily by creating new out migrants and repelling potential in migrants. A counterfactual analysis suggests that the uneven distribution of New Deal spending explains about twelve percent of the internal migration flows in the United States between 1935 and 1940.

The 2nd order renormalization group flow for non-linear sigma models in 2 dimensions

We show that for two dimensional manifolds M with negative Euler characteristic there exists subsets of the space of smooth Riemannian metrics which are invariant and either parabolic or backwards-parabolic for the 2nd order RG flow. We also show that solutions exists globally on these sets. Finally, we establish the existence of an eternal solution that has both a UV and IR limit, and passes through regions where the flow is parabolic and backwards-parabolic

Localization of aeroelastic modes in mistuned high-energy turbines

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77061/1/AIAA-23759-105.pd

The New Economics of Livestock Production Management

The importance of heterogeneity of animal attributes in livestock production is assessed. Preliminary results indicate that variance and skew measures of attributes may be becoming more important over time.livestock economics, herd management, livestock marketing, Livestock Production/Industries, Marketing,

Innate Pathways of Immune Activation in Transplantation

Studies of the immune mechanisms of allograft rejection have predominantly focused on the adaptive immune system that includes T cells and B cells. Recent investigations into the innate immune system, which recognizes foreign antigens through more evolutionarily primitive pathways, have demonstrated a critical role of the innate immune system in the regulation of the adaptive immune system. Innate immunity has been extensively studied in its role as the host's first-line defense against microbial pathogens; however, it is becoming increasingly recognized for its ability to also recognize host-derived molecules that result from tissue damage. The capacity of endogenous damage signals acting through the innate immune system to lower immune thresholds and promote immune recognition and rejection of transplant grafts is only beginning to be appreciated. An improved understanding of these pathways may reveal novel therapeutic targets to decrease graft alloreactivity and increase graft longevity

Neurophysiological Correlates of Executive Function: A Comparison of European-Canadian and Chinese-Canadian 5-Year-Old Children

This study explored the neurophysiological correlates of executive function (EF) in young children from two different cultural backgrounds. Twenty European-Canadian and 17 Chinese-Canadian 5-year-olds participated in a go/no-go task, during which high-density electroencephalographic (EEG) data were recorded. No cultural group differences were observed in children's behavioral performance on the task, but marked differences were revealed by ERP analyses, which focused on the amplitude and latency of the N2 waveform. Chinese-Canadian children showed larger (i.e., more negative) N2 amplitudes than European-Canadian children on the right side of the scalp on no-go trials, as well as on the left side of the scalp on go trials, and for all children, larger N2 amplitudes were associated with faster median reaction times. Source analyses of the N2 were consistent with the hypothesis that compared to European-Canadian children, Chinese-Canadian children showed more activation in dorsomedial, ventromedial, and (bilateral) ventrolateral prefrontal cortex. These findings reveal that EEG can provide a measure of cultural differences in neurocognitive function that is more sensitive than behavioral data alone; that Chinese-Canadian children show a pattern of hemispheric differentiation in the context of this task than that is more pronounced than that of age-matched European-Canadian children; that the asymmetrically lateralized N2 may be a reliable marker of both effortful inhibition (on the right) and effortful approach (on the left); and that the neural correlates of EF may vary across samples of healthy participants, even in children

Differential gaze behavior towards sexually preferred and non-preferred human figures

The gaze pattern associated with image exploration is a sensitive index of our attention, motivation and preference. To examine whether an individual’s gaze behavior can reflect his/her sexual interest, we compared gaze patterns of young heterosexual men and women (M = 19.94 years, SD = 1.05) while viewing photos of plain-clothed male and female figures aged from birth to sixty years old. Our analysis revealed a clear gender difference in viewing sexually preferred figure images. Men displayed a distinctive gaze pattern only when viewing twenty-year-old female images, with more fixations and longer viewing time dedicated to the upper body and waist-hip region. Women also directed more attention at the upper body on female images in comparison to male images, but this difference was not age-specific. Analysis of local image salience revealed that observers’ eye-scanning strategies could not be accounted for by low-level processes, such as analyzing local image contrast and structure, but were associated with attractiveness judgments. The results suggest that the difference in cognitive processing of sexually preferred and non-preferred figures can be manifested in gaze patterns associated with figure viewing. Thus, eye-tracking holds promise as a potential sensitive measure for sexual preference, particularly in men