Effects of acoustic sources

An experiment was conducted to determine the effect of acoustics on the laminar flow on the side of a nacelle. A flight test was designed to meet this goal and a brief review of the purpose is given. A nacelle with a significant length of laminar flow was mounted on the wing of NASA OV-1. Two noise sources are also mounted on the wing: one in the center body of the nacelle; the second in a wing mounted pod outboard of the nacelle. These two noise sources allow for a limited study of the effect of source direction in addition to control of the acoustic level and frequency. To determine the range of Tollmien-Schlichting frequencies, a stability analysis using the pressure coefficient distribution along the side of the nacelle was performed. Then by applying these frequencies and varying the acoustic level, a study of the receptivity of the boundary layer to the acoustic signal, as determined by the shortening of the length of laminar flow, was conducted. Results are briefly discussed

The acute respiratory distress syndrome in 2013.

Acute lung injury and the acute respiratory distress syndrome are major causes of morbidity and mortality in critically ill patients. This review focuses on new developments in definitions, epidemiology, clinical and basic research, and promising new directions in treatment. There is new information about the potential contribution of environmental factors, especially exposure to cigarette smoke. Pathologic findings in ARDS have been limited to case reports of open lung biopsies and post-mortem studies but there is some new information from a recent pathology study relative to the frequency of diffuse alveolar damage and the severity of arterial hypoxemia. Further, therapy with lung-protective ventilation and fluid conservative protocol has improved outcomes, but several new trials are in progress to test several promising strategies

Divide-and-conquer: A proportional, minimal-envy cake-cutting algorithm

We analyze a class of proportional cake-cutting algorithms that use a minimal number of cuts (n-1 if there are n players) to divide a cake that the players value along one dimension. While these algorithms may not produce an envy-free or efficient allocation--as these terms are used in the fair-division literature--one, divide-and-conquer (D&C), minimizes the maximum number of players that any single player can envy. It works by asking n ≥ 2 players successively to place marks on a cake--valued along a line--that divide it into equal halves (when n is even) or nearly equal halves (when n is odd), then halves of these halves, and so on. Among other properties, D&C ensures players of at least 1/n shares, as they each value the cake, if and only if they are truthful. However, D&C may not allow players to obtain proportional, connected pieces if they have unequal entitlements. Possible applications of D&C to land division are briefly discussed.mechanism design; fair division; divisible good; cake-cutting; divide-and-choose

Some Recent Results on Pie Cutting

For cake cutting, cuts are parallel to an axis and yield rectangular pieces. As such, cutting a cake is viewed as dividing a line segment. For pie cutting, cuts are radial from the center of a disc to the circumference and yield sectors or wedge-shaped pieces. As such, cutting a pie is viewed as dividing a circle. There is clearly a relationship between cutting a cake and cutting a pie. Once a circular pie has a single cut, then it can be straightened out into a segment, looking like a cake. Isn\u27t a cake just a pie that has been cut? Gale (1993) suggested that this topology was a significant difference. This note is to summarize and compare some of the recent results on pie cutting that appear in Barbanel and Brams (2007) and Brams, Jones, and Klamler (2007). The geometric framework presented in Barbanel and Brams (2007) is used to prove and to explain results in Brams, Jones, and Klamler (2007)

N-Person cake-cutting: there may be no perfect division

A cake is a metaphor for a heterogeneous, divisible good, such as land. A perfect division of cake is efficient (also called Pareto-optimal), envy-free, and equitable. We give an example of a cake in which it is impossible to divide it among three players such that these three properties are satisfied, however many cuts are made. It turns out that two of the three properties can be satisfied by a 3-cut and a 4-cut division, which raises the question of whether the 3-cut division, which is not efficient, or the 4-cut division, which is not envy-free, is more desirable (a 2-cut division can at best satisfy either envy-freeness or equitability but not both). We prove that no perfect division exists for an extension of the example for three or more players.Cake-cutting; fair division; efficiency; envy-freeness; equitability; heterogeneous good

Forming Stable Coalitions: The Process Matters

Players are assumed to rank each other as coalition partners. Two processes of coalition formation are defined and illustrated: i) Fallback (FB): Players seek coalition partners by descending lower and lower in their preference rankings until some majority coalition, all of whose members consider each other mutually acceptable, forms. ii) Build-up (BU):Same descent as FB, except only majorities whose members rank each other highest form coalitions. BU coalitions are stable in the sense that no member would prefer to be in another coalition, whereas FB coalitions, whose members need not rank each other highest, may not be stable. BU coalitions are bimodally distributed in a random society, with peaks around simple majority and unanimity the distributions of majorities in the US Supreme Count and in the US House of Representatives follow this pattern. The dynamics of real-life coalition-formation processes are illustrated by two Supreme Court cases.Coalition dynamics, Fallback bargaining, Manipulability, Legislatures, US Supreme Court

Designing a Digital Employee Experience for Research Administration Using a Sequential Mixed-Methods Approach

This dissertation examines the concept of digital employee experience in the research administration industry. Using a digital employee experience framework, the study examined how the pandemic impacted the research administration work environment. This dissertation presents perceptions and draws insights from research administration leaders, management, and staff on digital work and digital employee experiences through the pandemic. The dissertation was motivated by three research questions: (1) What challenges did research administrators encounter during the Pandemic? (2) What were the research administrators’ perceptions of digital transformation during their employee journey? and (3) What is the future of research administration as the industry moves forward post-pandemic? Previous literature indicated that the digital employee experience framework was comprised of eight essential components: technology, physical environment, culture, business strategy, leadership, career, brand, and personal. Since the 2020 pandemic began, various studies of digital work environments, digital employee experiences, and remote work have been conducted. However, there have been limited studies of the research administration industry. This dissertation will advance the work of Gheidar and Zanjani (2021) and provide an understanding of the digital employee experience in the research administration community. To study research administration\u27s perceptions of digital work environments and digital employee experiences from a holistic perspective, a sequential mixed methods approach utilizing quantitative and qualitative research methods was selected. During the first phase of the research, the objective was to obtain top-down digital transformation and digital workplace insights by interviewing 11 United States Research Administration leaders. The second phase of the research included surveying 548 research administrators who provided their insights on the digital work environment, digital employee experiences and the future of research administration. The key findings from the research revealed that maintaining team culture in a digital environment is challenging and that leaders must be creative and innovative to maintain the culture of their teams. The Pandemic transformed the landscape of research administration at the team and organizational levels by changing from fully in-person office models to remote and hybrid models. This transformation created challenges and obstacles for management and staff, prompting them to rethink how to perform research administration business in different environments. The study indicated that leadership should invest in Digital Employee Experience tools and practices as we enter this new research administration world. These tools and practices can provide positive employee experiences in a digital environment. In conclusion, RA work must continue to adapt to an ever more digitalized world. Future research should focus on finding ways to maintain culture and gather ongoing faculty research perspectives on the evolution of the digital work environment in research administration

Space Station alpha joint bearing

Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described