Local structure of intercomponent energy transfer in homogeneous turbulent shear flow

Intercomponent energy transfer by pressure-strain-rate was investigated for homogeneous turbulent shear flow. The rapid and slow parts of turbulent pressure (decomposed according to the influence of the mean deformation rate) are found to be uncorrelated; this finding provides strong justification for current modeling procedure in which the pressure-strain-rate term is split into the corresponding parts. Issues pertinent to scales involved in the intercomponent energy transfer are addressed in comparison with those for the Reynolds-stress and vorticity fields. A physical picture of the energy transfer process is described from a detailed study of instantaneous events of high transfer regions. It was found that the most significant intercomponent energy transfer events are highly localized in space and are imbedded within a region of concentrated vorticity

Pressure-strain-rate events in homogeneous turbulent shear flow

A detailed study of the intercomponent energy transfer processes by the pressure-strain-rate in homogeneous turbulent shear flow is presented. Probability density functions (pdf's) and contour plots of the rapid and slow pressure-strain-rate show that the energy transfer processes are extremely peaky, with high-magnitude events dominating low-magnitude fluctuations, as reflected by very high flatness factors of the pressure-strain-rate. A concept of the energy transfer class was applied to investigate details of the direction as well as magnitude of the energy transfer processes. In incompressible flow, six disjoint energy transfer classes exist. Examination of contours in instantaneous fields, pdf's and weighted pdf's of the pressure-strain-rate indicates that in the low magnitude regions all six classes play an important role, but in the high magnitude regions four classes of transfer processes, dominate. The contribution to the average slow pressure-strain-rate from the high magnitude fluctuations is only 50 percent or less. The relative significance of high and low magnitude transfer events is discussed

Education, Technology, and Media: A Peak into My Summer Internship at NASA Glenn Research Center in Cleveland, Ohio

My name is James Moon and I am a senor at Tennessee State University where my major is Aeronautical and Industrial Technology with a concentration in industrial electronics. I am currently serving my internship in the Engineering and Technical Services Directorate at the Glenn Research Center (GRC). The Engineering and Technical Service Directorate provides the services and infrastructure for the Glenn Research Center to take research concepts to reality. They provide a full range of integrated services including engineering, advanced prototyping and testing, facility management, and information technology for NASA, industry, and academia. Engineering and Technical Services contains the core knowledge in Information Technology (IT). This includes data systems and analysis, inter and intranet based systems design and data security. Including the design and development of embedded real-time sohare applications for flight and supporting ground systems, Engineering and Technical Services provide a wide range of IT services and products specific to the Glenn Research Center research and engineering community

[The Engineering and Technical Services Directorate at the Glenn Research Center]

My name is James Moon and I am a senior at Tennessee State University where my major is Aeronautical and Industrial Technology with a concentration in industrial electronics. I am currently serving my internship in the Engineering and Technical Services Directorate at the Glenn Research Center (GRC). The Engineering and Technical Service Directorate provides the services and infrastructure for the Glenn Research Center to take research concepts to reality. They provide a full range of integrated services including engineering, advanced prototyping and testing, facility management, and information technology for NASA, industry, and academia. Engineering and Technical Services contains the core knowledge in Information Technology (IT). This includes data systems and analysis, inter and intranet based systems design and data security. Including the design and development of embedded real-time s o h a r e applications for flight and supporting ground systems, Engineering and Technical Services provide a wide range of IT services and products specific to the Glenn Research Center research and engineering community. In the 7000 Directorate I work directly in the 7611 organization. This organization is known as the Aviation Environments Technical Branch. My mentor is Vincent Satterwhite who is also the Branch Chief of the Aviation Environments Technical Branch. In this branch, I serve as the Assistant program manager of the Engineering Technology Program. The Engineering Technology Program (ETP) is one of three components of the High School L.E.R.C.I.P. This is an Agency-sponsored, eight-week research-based apprenticeship program designed to attract traditionally underrepresented high school students that demonstrate an aptitude for and interest in mathematics, science, engineering, and technology

Optimal developmental test programs for one-shot systems

This dissertation considers two developmental testing models for one-shot systems, non-repairable devices that are destroyed by testing or first normal use (for example, rocket engines) when there is the potential for reliability growth through redesign. Given a limited budget and fixed cost per redesign, we wish to determine the sequence of redesigns and tests so that the expected number of effective systems in an ultimate stockpile of systems of the final design is maximized. We develop mathematical models and analyses which describe the optimal testing policies for this sequential decision problem. Further, we present properties of the models which, in some cases, make the computation of solutions feasible. We begin with the analysis of a two-state reliability model. Besides determining the effect of redesign costs on the optimal strategy, we show how the possibility of harmful redesigns can be incorporated into the model. We explore how this model behaves when even a poor reliability design is highly reliable but extremely high reliability is desired. A primary contribution of the thesis is an analysis of the general multiple-state (k-state) reliability model and, most interestingly, the presentation of a 2-variable formulation by which some k-state models can be analyzed. Under some restrictions, we analyze and compute solutions to this latter model on a lattice

Missional Prayer : The Ebenezer Model as a Relational Catalyst for Disciple Making Through the Collegedale Seventh-day Adventist Church

Problem In a 2010 missional assessment, the Collegedale Seventh-day Adventist Church was made aware of a missional blind spot in relation to the external needs of its ministry context. A 2017 MinistryInsight.com Priorities Report also identified the region\u27s desire for warmth and friendship from religious communities as a top ministry preference. In a 2018 effort to begin addressing these needs, Collegedale’s pastoral staff chose Christ has called us to Make Friends, an actionable expression of Jesus\u27 commission to make disciples. In light of these factors, the Collegedale Church needs a relational catalyst to encourage attenders and members to make friends for Jesus. Method In this study the Ebenezer Model of Missional Prayer was created to be a relational catalyst for discipleship and tested through a series of eight Ebenezer LifeGroup lessons. The purpose of this ministry intervention was to increase participant’s missional instincts; specifically, awareness of God’s presence, responsiveness to His voice, and interpersonal courage in making friends for Christ through listening and prayer. Group participants experimented with prayer as communion and prayer as commission through the four missional HELP practices of Heeding, Engaging, Listening, and Prayer. The Ebenezer Model of Missional Prayer and Ebenezer LifeGroup intervention were evaluated through an online survey, before and after focus groups, and exit interviews. Results Eleven out of 14 recruits attended the opening focus group and orientation. Nine people completed the eight-week Ebenezer LifeGroup. Members in this study experienced a clear and identifiable shift toward a more missional outlook in relation to their awareness of God, responsiveness to His voice, and interpersonal courage for Christ. They grew in their willingness to minister to people through the HELP Practices of Heeding, Engaging, Listening, and Prayer. Conclusions Through the Ebenezer Model of Missional Prayer there is an opportunity for church goers to grow in their courage to make disciples as they learn to minister through listening and prayer. The Ebenezer Model is effective for new and established believers. It affirms prior discipleship experiences and provides tools for greater effectiveness and confidence in disciple making

Sets Characterized by Missing Sums and Differences in Dilating Polytopes

A sum-dominant set is a finite set $A$ of integers such that $|A+A| > |A-A|$. As a typical pair of elements contributes one sum and two differences, we expect sum-dominant sets to be rare in some sense. In 2006, however, Martin and O'Bryant showed that the proportion of sum-dominant subsets of $\{0,\dots,n\}$ is bounded below by a positive constant as $n\to\infty$. Hegarty then extended their work and showed that for any prescribed $s,d\in\mathbb{N}_0$, the proportion $\rho^{s,d}_n$ of subsets of $\{0,\dots,n\}$ that are missing exactly $s$ sums in $\{0,\dots,2n\}$ and exactly $2d$ differences in $\{-n,\dots,n\}$ also remains positive in the limit. We consider the following question: are such sets, characterized by their sums and differences, similarly ubiquitous in higher dimensional spaces? We generalize the integers in a growing interval to the lattice points in a dilating polytope. Specifically, let $P$ be a polytope in $\mathbb{R}^D$ with vertices in $\mathbb{Z}^D$, and let $\rho_n^{s,d}$ now denote the proportion of subsets of $L(nP)$ that are missing exactly $s$ sums in $L(nP)+L(nP)$ and exactly $2d$ differences in $L(nP)-L(nP)$. As it turns out, the geometry of $P$ has a significant effect on the limiting behavior of $\rho_n^{s,d}$. We define a geometric characteristic of polytopes called local point symmetry, and show that $\rho_n^{s,d}$ is bounded below by a positive constant as $n\to\infty$ if and only if $P$ is locally point symmetric. We further show that the proportion of subsets in $L(nP)$ that are missing exactly $s$ sums and at least $2d$ differences remains positive in the limit, independent of the geometry of $P$. A direct corollary of these results is that if $P$ is additionally point symmetric, the proportion of sum-dominant subsets of $L(nP)$ also remains positive in the limit.Comment: Version 1.1, 23 pages, 7 pages, fixed some typo

Analyzing social experiments as implemented: evidence from the HighScope Perry Preschool Program

Social experiments are powerful sources of information about the effectiveness of interventions. In practice, initial randomization plans are almost always compromised. Multiple hypotheses are frequently tested. "Significant" effects are often reported with p-values that do not account for preliminary screening from a large candidate pool of possible effects. This paper develops tools for analyzing data from experiments as they are actually implemented. We apply these tools to analyze the influential HighScope Perry Preschool Program. The Perry program was a social experiment that provided preschool education and home visits to disadvantaged children during their preschool years. It was evaluated by the method of random assignment. Both treatments and controls have been followed from age 3 through age 40. Previous analyses of the Perry data assume that the planned randomization protocol was implemented. In fact, as in many social experiments, the intended randomization protocol was compromised. Accounting for compromised randomization, multiple-hypothesis testing, and small sample sizes, we find statistically significant and economically important program effects for both males and females. We also examine the representativeness of the Perry study. Download appendix