4,558 research outputs found
Feasibility Study of SDAS Instrumentation's Ability to Identify Mobile Launcher (ML)/Crawler-Transporter (CT) Modes During Rollout Operations
The Space Launch System (SLS) and its Mobile Launcher (ML) will be transported to the launch pad via the Crawler-Transporter (CT) system. Rollout (i.e., transportation) loads produce structural loads on the integrated SLS/Orion Multi-Purpose Crew Vehicle (MPCV) launch vehicle which are of a concern with respect to fatigue. As part of the risk reduction process and in addition to the modal building block test approach that has been adopted by the SLS Program, acceleration data will be obtained during rollout for use in modal parameter estimation. There are several occurrences where the ML/CT will be transported either into the Vertical Assembly Building (VAB) or to the launch pad and back without the SLS stack as part of the Kennedy Space Center (KSC) Exploration Ground Systems (EGS) Integrated Test and Checkout (ITCO). NASA KSC EGS has instrumentation installed on both the ML and CT to record data during rollout, at the launch pad, and during liftoff. The EGS instrumentation on the ML, which includes accelerometers, is referred to as the Sensor Data Acquisition System (SDAS). The EGS instrumentation on the CT, which also includes accelerometers, is referred to as the CT Data Acquisition System (CTDAS). The forces and accelerations applied to the ML and CT during a rollout event will be higher than any of the planned building block modal tests. This can be very beneficial in helping identify nonlinear behavior in the structure. Developing modal parameters from the same test hardware in multiple boundary conditions and under multiple levels of excitation is a key step in developing a well correlated FEM. The purpose of this study was three fold. First, determine the target modes of the ML/CT in its rollout configuration. Second, determine if the test degrees of freedom (DOF) corresponding to the layout of the SDAS/CTDAS accelerometers (i.e. position and orientation) is sufficient to identify the target modes. Third, determine if the Generic Rollout Forcing Functions (GRFF's) is sufficient for identifying the ML/CT target modes accounting for variations in CT speed, modal damping, and sensor/ambient background noise levels. The finding from the first part of this study identified 28 target modes of the ML/CT rollout configuration based upon Modal Effective Mass Fractions (MEFF) and engineering judgement. The finding from the second part of this study showed that the SDAS/CTDAS accelerometers (i.e. position and orientation) are able to identify a sufficient number of the target modes to support model correlation of the ML/CT FEM. The finding from the third part of this study confirms the GRFFs sufficiently excite the ML/CT such that varying quantities of the defined target modes should be able to be extracted when utilizing an Experimental Modal Analysis (EMA) Multi-Input Multi-Output (MIMO) analysis approach. An EMA analysis approach was used because Operational Modal Analysis (OMA) tools were not available and the GRFFs were sufficiently uncorrelated. Two key findings from this third part of the study are that the CT speed does not show a significant impact on the ability to extract the modal parameters and that keeping the ambient background noise observed at each accelerometer location at or below 30 grms is essential to the success of this approach
Electrocatalyst decorated hematite nanowire arrays for photoelectrochemical water splitting.
Solar power is a leading option for renewable energy. However, storing solar energy is one of the leading pitfalls in this field, and one viable option is to store solar energy in chemical bonds, for example in H2 via water splitting. Hematite, α-Fe2O3, is one of the possible semiconductors that has been researched to drive photoelectrolysis of water. Hematite alone is not a decent material for photoelectrolysis because of the large activation energy required to begin the reaction. To make hematite more useful for photoelectrolysis an electrocatalyst, such as nickel oxide, is needed. In this experiment, nickel (II) nitrate was dissolved into distilled water; then, the solution was applied to hematite nanowires and exposed to atmospheric oxygen plasma. This left a coating of nickel oxide particles on the surface of the nanowires. The hematite with a nickel oxide catalyst can be used in this form to drive the water splitting reaction. After plasma deposition, it can also be placed in an oven at 550 ºC for an hour to anneal the sample, which creates a biphasic surface layer of nickel oxide and iron oxide. After annealing, the nickel oxide/hematite samples can be used to catalyze water splitting. The use of the electrocatalyst on the substrate improved the electrolysis of water by decreasing the overpotential by approximately 300mV. Annealing the nickel oxide and hematite decreases the overpotential by the same amount as the unannealed nickel oxide layer covering the Fe2O3. Both unannealed and annealed samples show photoactivity, but annealing increases the photovoltage. The physical properties are tested using transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDX), which shows catalyst particles were created on the surface of the hematite nanowire array
Education ain\u27t black: the disidentification of African American students
In this thesis, I will discuss the influence of education on the identity formation of African American students. Based on the scholarly literature in education theory, I will argue in Bourdieuan theory education, formal education, fails to accommodate the specific needs of African American students because education influences African American students to develop constructions of “whiteness that education reinforces. As education attempts to uphold the “status quo” of American society, education simultaneously forces African American students to question the relevance of education. In questioning the relevance of education through high-achieving African American students’ use of language and pursuit of academic achievement, low-achieving African American students offer a critique of education that characterizes education as a “white-dominated” system where individuals must embody whiteness in order to achieve social acceptance. As a result, African American students choose to “disidentify” with education rather than to assimilate into White culture to avoid being identified as “white”− speaking Standard English, following rules and regulations, and maintaining a high grade point average. This critique of education− though not an anti-intellectual response to education because most African Americans still view education as a means to social mobility− signifies education does not educate African American students but instead produces “white” African American students in order to reproduce societal norms. I will also propose the incorporation of self-knowledge into critical education will facilitate an awareness of personal history and self-worth among African American students not only to disrupt an educational structure of inequality but also to foster a positive self-concept within these students
Expert elicitation of seasonal abundance of North Atlantic right whales Eubalaena glacialis in the mid-Atlantic
This work was supported in part by US Office of Naval Research (ONR) grants to E.F.: N00014-09-1-0896 at University of California, Santa Barbara and N00014-12-1-0274 at University of California, Davis. This work was also supported by ONR grant N000141210286 to the University of St Andrews. In addition, we gratefully acknowledge funding for this work from The Marine Alliance for Science and Technology for Scotland (MASTS). MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.North Atlantic right whales (Eubalaena glacialis; henceforth right whales) are among the most endangered large whales. Although protected since 1935, their abundance has remained low. Right whales occupy the Atlantic Ocean from southern Greenland and the Gulf of St. Lawrence south to Florida. The highly industrialized mid-Atlantic region is part of the species’ migratory corridor. Gaps in knowledge of the species’ movements through the mid-Atlantic limit informed management of stressors to the species. To contribute to filling of these gaps, we elicited estimates of the relative abundance of adult right whales in the mid-Atlantic during four months, representing each season, from ten experts. We elicited the minimum, maximum, and mode as the number of individuals in a hypothetical population of 100 right whales, and confidence estimates as percentages. For each month-sex combination, we merged the ten experts’ answers into one distribution. The estimated modes of relative abundances of both sexes were highest in January and April (females, 29 and 59; males, 22 and 23) and lowest in July and October (females, five and nine; males, three and five). In some cases, our elicitation results were consistent with the results of studies based on sightings data. However, these studies generally did not adjust for sampling effort, which was low and likely variable. Our results supplement the results of these studies and will increase the accuracy of priors in complementary Bayesian models of right whale abundances and movements through the mid-Atlantic.Publisher PDFPeer reviewe
Unequal incomes, unequal outcomes? Economic inequality and measures of well-being: summary of observations and recommendations
This is a summary of the proceedings of the conference "Unequal incomes, unequal outcomes? Economic inequality and measures of well-being." The conference was held at the Federal Reserve Bank of New York on May 7, 1999. The conference was organized to focus on the evolution of more direct measures of the material well-being of Americans. Of particular concern was the impact of income inequality on trends in health, housing, and crime victimization. Conference participants also examined some of the changes in policymakers' responses to these trends, especially in the areas of education financing and local governance. Finally, the participants discussed efforts to evaluate the social consequences of policy reforms and offered some guidelines on the best direction for future research and policy initiatives.Income distribution ; Public policy
Recommended from our members
An Examination of Motivation to Change and Neural Alcohol Cue Reactivity Following a Brief Intervention.
Background: Brief interventions represent a promising psychological intervention targeting individuals with heavy alcohol use. Motivation to change represents an individual's openness to engage in a behavior change strategy and is thought to be a crucial component of brief interventions. Neuroimaging techniques provide a translational tool to investigate the neurobiological mechanisms underlying potential mediators of treatment response, including motivation to change. Therefore, this study aimed to examine the effect of a brief intervention on motivation to change drinking behavior and neural alcohol taste cue reactivity. Methods: Non-treatment-seeking heavy drinkers were randomized to receive a brief drinking intervention (n = 22) or an attention-matched control (n = 24). Three indices of motivation to change were assessed at baseline and after the intervention or control session: importance, confidence, and readiness. Immediately following the intervention or control session, participants also underwent an functional magnetic resonance imaging (fMRI) during which they completed an alcohol taste cues paradigm. Results: There was a significant effect of the brief intervention on increasing ratings of importance of changing drinking behavior, but not on ratings of confidence or readiness to change. Ratings of importance after the intervention or control session were associated with neural alcohol taste cue reactivity, but notably, this effect was only significant for participants who received the intervention. Individuals in the intervention condition showed a positive association between ratings of importance and activation in the precuneus, posterior cingulate, and insula. Conclusions: The brief drinking intervention was successful at improving one dimension of motivation to change among non-treatment-seeking heavy drinkers. The brief intervention moderated the relationship between ratings of importance and brain activation in circuitry associated with interoceptive awareness and self-reflection. Together, findings represent an initial step toward understanding the neurobiological mechanisms through which a brief intervention may improve motivation to change
Comparing Substance Use Social Issues in Appalachian and non-Appalachian Regions in Kentucky
Substance use and abuse is not a uniquely Appalachian problem, but it remains a prevalent social problem for the geographical region. Kentucky has been one of the central states experiencing generations of substance abuse, ranging from methamphetamines to OxyContin to heroin. Eastern Kentucky, which includes a portion of Central Appalachia, has been a focal point for the proposed war against substance use. What remains undemonstrated in studies is exactly how substance abuse differs between the Central Appalachian counties of Eastern Kentucky and the remainder of the state, if any difference exists at all. In this study, the researchers examine how drug mortality, nonfatal overdoses, emergency room substance abuse diagnoses, and inpatient hospital substance abuse rates vary between Appalachian and non-Appalachian counties in Kentucky. Results indicate that there is a marginal difference in drug fatalities and a statistical difference in both emergency room and inpatient diagnoses of substance abuse. However, the non-fatal overdose rate is nearly identical for Appalachian and non-Appalachian counties across the state. The authors argue this can be explained through Relative Deprivation Theory, persistent underdevelopment of Kentucky’s Appalachian counties, and medical use practices in the region. The researchers close with recommendations on reconsidering how substance use is treated
Covariate Adjustment in Bayesian Adaptive Clinical Trials
In conventional randomized controlled trials, adjustment for baseline values
of covariates known to be at least moderately associated with the outcome
increases the power of the trial. Recent work has shown particular benefit for
more flexible frequentist designs, such as information adaptive and adaptive
multi-arm designs. However, covariate adjustment has not been characterized
within the more flexible Bayesian adaptive designs, despite their growing
popularity. We focus on a subclass of these which allow for early stopping at
an interim analysis given evidence of treatment superiority. We consider both
collapsible and non-collapsible estimands, and show how to obtain posterior
samples of marginal estimands from adjusted analyses. We describe several
estimands for three common outcome types. We perform a simulation study to
assess the impact of covariate adjustment using a variety of adjustment models
in several different scenarios. This is followed by a real world application of
the compared approaches to a COVID-19 trial with a binary endpoint. For all
scenarios, it is shown that covariate adjustment increases power and the
probability of stopping the trials early, and decreases the expected sample
sizes as compared to unadjusted analyses.Comment: 17 pages, 5 tables, 4 figure
- …