Evaluation of a large capacity heat pump concept for active cooling of hypersonic aircraft structure

Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept

Improved prediction of laminar leading edge separation

Research was conducted to provide a definite criterion for the prediction of the bubble burst on airfoils typical of those used for fighter wings. The approach taken was to correlate existing airfoil bubble burst data using various parameters at the laminar separation point. The method due to Weber was modified to provide a continuous analytic solution for the velocity distribution around the airfoil leading edge. Coupling the modified Weber method with the Stratford laminar separation prediction method leads to a universal chart giving the conditions at separation as a function of stagnation location and leading edge radius. Application of the combined method to available two-dimensional airfoil data resulted in an empirical criterion presenting the limiting local velocity gradient at separation as a function of the boundary layer momentum thickness at separation for bubble burst. The correlation leads as well to the qualitative explanation of two types of laminar stall: thin airfoil and leading edge. The validity of the correlation is demonstrated by predicting the lift coefficient and angle of attack for stall on airfoils with leading edge or trailing edge flaps

A method of calculating compressible turbulent boundary layers

Equations of motion for calculating compressible turbulent boundary layer

Computer program for calculating laminar and turbulent boundary layer development in compressible flow

A computer program is described which performs a numerical integration of the equations of motion for a compressible two-dimensional boundary layer. Boundary layer calculations may be carried out for both laminar and turbulent flow for arbitrary Reynolds number and free stream Mach number distribution on planar or axisymmetric bodies with wall heating or cooling, longitudinal wall curvature, wall suction or blowing, and a rough or a smooth wall. A variety of options are available as initial conditions. The program can generate laminar initial conditions such as Falkner-Skan similarity solutions (so that initial wedge flows can be simulated including Blasius or stagnation point flow) or approximate equilibrium turbulent profiles. Alternatively, initial profile input data can be utilized

Prioritizing Patients: Stochastic Dynamic Programming for Surgery Scheduling and Mass Casualty Incident Triage

The research presented in this dissertation contributes to the growing literature on applications of operations research models to problems in healthcare through the development and analysis of mathematical models for two fundamental problems facing nearly all hospitals: the single-day surgery scheduling problem and planning for triage in the event of a mass casualty incident. Both of these problems can be understood as sequential decision-making processes aimed at prioritizing between different classes of patients under significant uncertainty and are modeled using stochastic dynamic programming. Our study of the single-day surgery scheduling problem represents the first model to capture the sequential nature of the operating room (OR) manager's decisions during the transition between the generality of cyclical block schedules (which allocate OR time to surgical specialties) and the specificity of schedules for a particular day (which assign individual patients to specific ORs). A case study of the scheduling system at the University of Maryland Medical Center highlights the importance of the decision to release unused blocks of OR time and use them to schedule cases from the surgical request queue (RQ). Our results indicate that high quality block release and RQ decisions can be made using threshold-based policies that preserve a specific amount of OR time for late-arriving demand from the specialties on the block schedule. The development of mass casualty incident (MCI) response plans has become a priority for hospitals, and especially emergency departments and trauma centers, in recent years. Central to all MCI response plans is the triage process, which sorts casualties into different categories in order to facilitate the identification and prioritization of those who should receive immediate treatment. Our research relates MCI triage to the problem of scheduling impatient jobs in a clearing system and extends earlier research by incorporating the important trauma principle that patients' long-term (post-treatment) survival probabilities deteriorate the longer they wait for treatment. Our results indicate that the consideration of deteriorating survival probabilities during MCI triage decisions, in addition to previously studied patient characteristics and overall patient volume, increases the total number of expected survivors

A Phenomenological Approach to Understanding the S.T.R.O.N.G. MENtoring Program: An African-American Male Retention Program at a Midsize Predominantly White Institution

Using phenomenological inquiry, the purpose of this present research was to explore the phenomena of the African-American undergraduate male experience in a retention program at a Midsize Midwestern predominantly White institution. Through data analysis the principle researcher examined the perceptions of the participants to understand the impact of the program. The participants accounted for their shared experiences as being a part of the S.T.R.O.N.G. MENtoring program during the 2011-2012 academic school year. Collectively the participants articulated a greater sense of awareness to their self-perception due their socialization at the site location. The participants also warranted feelings of confirmation biases, an increased obligation to the program, and the need for counter space. The principle researcher addresses the themes emerged from data analysis and provides implications for the future direction and guidance for the S.T.R.O.N.G. MENtoring program

Compressive behavior of titanium alloy skin-stiffener specimens selectively reinforced with boron-aluminum composite

A method of selectively reinforcing a conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing was successfully demonstrated in compression tests of short skin-stiffener specimens. In a comparison with all-titanium specimens, improvements in structural performance recorded for the composite-reinforced specimens exceeded 25 percent on an equivalent-weight basis over the range from room temperature to 700 K (800 F) in terms of both initial buckling and maximum strengths. Performance at room temperature was not affected by prior exposure at 588 K (600 F) for 1000 hours in air or by 400 thermal cycles between 219 K and 588 K (-65 F and 600 F). The experimental results were generally predictable from existing analytical procedures. No evidence of failure was observed in the braze between the boron-aluminum composite and the titanium alloy

Fathers and substance misuse: a literature review

Purpose To review the following research questions from the available literature: • What evidence is there to suggest that substance misuse specifically by fathers (including alcohol and other drugs) causes wider harms, including child welfare concerns? • How do professionals respond specifically to substance misuse by fathers? • Do interventions aimed at parental substance misuse (particularly in the UK) include both mothers and fathers and if so how? Design/methodology/approach Scoping literature review, identifying 34 papers, (including scoping reviews published in 2006 and 2008 and six cited papers, covering the period 1990 – 2005), and 26 additional studies published between 2002 and 2020. Findings The review is organized into six themes: 1) Negative impact of men’s substance misuse problems on their parenting behaviours 2) Quality of the relationship between parents is affected by substance misuse of the fathers, in turn affecting the parenting behaviour and outcomes for child/ren 3) Importance to fathers of their fathering role (for example as financial provider) 4) Difficulties fathers may face in developing their fathering role 5) Sidelining of the fathering role in substance misuse services 6) Professionals tending to focus on the mother’s role in parenting inventions and services Originality The review focuses on fathers and substance misuse, an under-researched field within the wider contexts of fathering research and research into parental substance misus