Three-dimensional finite element analysis of acoustic instability of solid propellant rocket motors

A three dimensional finite element solution of the acoustic vibration problem in a solid propellant rocket motor is presented. The solution yields the natural circular frequencies of vibration and the corresponding acoustic pressure mode shapes, considering the coupled response of the propellant grain to the acoustic oscillations occurring in the motor cavity. The near incompressibility of the solid propellant is taken into account in the formulation. A relatively simple example problem is solved in order to illustrate the applicability of the analysis and the developed computer code

Ground simulation and tunnel blockage for a swept, jet-flapped wing tested to very high lift coefficients

Ground effects experiments and large/small tunnel interference studies were carried out on a model with a 20 inch (50.8 cm) 25 degree swept wing. The wing is slatted, has a 60 degree knee-blown flap and can be fitted with unflapped tips. A tail rake of pitch-yaw probes can be fitted to the fuselage. Certain check tests were also made with a very similar straight-wing model

Understanding and Equipping Female Leadership at Prosperous Temple Church of God in Christ

Debates on whether women qualify to take up church leadership have persisted over the years. In 2016, there was an instance in Alabama where a woman was appointed as the assistant pastor of a church. Within three months of her service, the number of congregants dropped. Efforts by the church management to unravel the cause of the decline revealed that a majority of the people, particularly women, who canceled their church attendance were uncomfortable with women taking up leadership positions. The case informed this research, which will use the case study of Prosperous Temple Church of God in Christ. The study will explore perceptions of whether women should take up church leadership positions or not

Dysregulation of NAD+ metabolism induces a Schwann cell dedifferentiation program

The Schwann cell (SC) is the major component of the peripheral nervous system (PNS) that provides metabolic and functional support for peripheral axons. The emerging roles of SC mitochondrial function for PNS development and axonal stability indicate the importance of SC metabolism in nerve function and in peripheral neuropathies associated with metabolic disorders. Nicotinamide adenine dinucleotide (NA

The Darkside - 50 Experiment: Election Recoil Calibrations and a Global Energy Variable.

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017

Effects of impingement of rocket exhaust gases and solid particles on a spacecraft Interim report, Mar. 18 - Oct. 25, 1966

Impingement damage to spacecraft from rocket exhaust gases and micron sized metal particle

Ground simulation and tunnel blockage for a jet-flapped, basic STOL model tested to very high lift coefficients

Ground effects experiments and large/small-tunnel interference studies were carried out on a model with a 20-inch (50.8 cm) span wing. The wing, which includes a highly deflected knee-blown flap can be fitted with unflapped tips and slats. A low-mounted tailplane can be fitted to the aft fuselage. Three-component balance meaurements, made with a fixed ground equipped with a single boundary-layer blowing slot, were compared with datum, moving-ground results. Good comparisons were obtained up to model blowing momentum coefficients of approximately two, after which the particular floor blowing settings used proved insufficient to prevent floor separation in the vicinity of the model. Skin friction measurements, taken routinely along the floor centerline, proved invaluable during the analysis of results, and their use is recommended as input to determination of floor BLC setting. A careful investigation was made of pitching moments, including tail-on, close-to-ground cases, with favorable results. Drag proved the most sensitive to the change from a moving to the boundary-layer controlled ground

Calcium Oxalate Urolithiasis in the Rat: Is it a Model for Human Stone Disease? A Review of Recent Literature

Calcium oxalate stone disease is the most common human urinary stone disease in the Western Hemisphere. To understand different aspects of the disease, calcium oxalate urolithiasis in the rat is used as a model. Spontaneous calcium oxalate urolithiasis is very rare in rats. Thus the disease is experimentally induced and the rats are generally made hyperoxaluric either by administration of excess oxalate, exposure to the toxin ethylene glycol, or various nutritional manipulations. All the experimental models show renal injury associated with crystal deposition. Calcium oxalate crystals are in most cases intraluminal in renal tubules and often attached to the basal lamina of the denuded epithelium. Rat renal papillary tips and fornices appear to be the preferential sites for the deposition of large calcium oxalate calculi. Where urinary supersaturation of calcium oxalate has been studied the crystal forming rat urines are shown to have higher urinary supersaturation of calcium oxalate than their controls. Oxalate metabolism in the rat is nearly identical to that in humans. Thus, in a number of respects, experimental calcium oxalate urolithiasis in the rat is similar to calcium oxalate stone disease in man

Retention of Calcium Oxalate Crystals in Renal Tubules

Crystal retention within the renal tubules is essential for nephrolithiasis and the development of urinary stone disease. We studied the mechanisms involved in this process by inducing calcium oxalate crystal deposition within the rat renal tubules and examining them using various microscopic techniques. Crystals appeared to be retained either by attachment to the tubular epithelium or by aggregating with other crystals thus becoming large enough to be retained by their collective size