Axisymmetric two-phase perfect gas performance program

Computer program calculates the inviscid axisymmetric nozzle expansion of propellant systems having both gaseous and condensed exhaust products. The program uses velocity and thermal lags and will perform calculations for contoured and conical nozzles

Improved Two-Dimensional Kinetics (TDK) computer program

Fluid properties, the boundary layer module, and regenerative cooling are discussed. Chemistry, low density flow effects, test cases, input and output for TDK, and documentation are also discussed

Performance predictions for an SSME configuration with an enlarged throat

The Two Dimensional Kinetics (TDK) computer program that was recently developed for NASA was used to predict the performance of a Large Throat Configuration of the Space Shuttle Main Engine (SSME). Calculations indicate that the current design SSME contains a shock wave that is induced by the nozzle wall shape. In the Large Throat design an even stronger shock wave is predicted. Because of the presence of this shock wave, earlier performance predictions that have neglected shock wave effects have been questioned. The JANNAF thrust chamber performance prediction procedures given in a reference were applied. The analysis includes the effects of two dimensional reacting flow with a shock wave. The effects of the boundary layer with a regenatively cooled wall are also included. A Purdue computer program was used to compute axially symmetric supersonic nozzle flows with an induced shock, but is restricted to flows with a constant ratio of specific heats. Thus, the TDK program was also run with ths assumption and the results of the two programs were compared

Additional support for the TDK/MABL computer program

An advanced version of the Two-Dimensional Kinetics (TDK) computer program was developed under contract and released to the propulsion community in early 1989. Exposure of the code to this community indicated a need for improvements in certain areas. In particular, the TDK code needed to be adapted to the special requirements imposed by the Space Transportation Main Engine (STME) development program. This engine utilizes injection of the gas generator exhaust into the primary nozzle by means of a set of slots. The subsequent mixing of this secondary stream with the primary stream with finite rate chemical reaction can have a major impact on the engine performance and the thermal protection of the nozzle wall. In attempting to calculate this reacting boundary layer problem, the Mass Addition Boundary Layer (MABL) module of TDK was found to be deficient in several respects. For example, when finite rate chemistry was used to determine gas properties, (MABL-K option) the program run times became excessive because extremely small step sizes were required to maintain numerical stability. A robust solution algorithm was required so that the MABL-K option could be viable as a rocket propulsion industry design tool. Solving this problem was a primary goal of the phase 1 work effort

Axisymmetric reacting gas nonequilibrium performance program

Computer program calculates the inviscid one-dimensional equilibrium, frozen, and nonequilibrium nozzle expansion of propellant exhaust mixtures containing these six elements - carbon, hydrogen, oxygen, nitrogen, fluorine, and chlorine plus either aluminum, beryllium, boron or lithium. This program will perform calculations for contoured and conical nozzles

Engineering and programming manual: Two-dimensional kinetic reference computer program (TDK)

The Two Dimensional Kinetics (TDK) computer program is a primary tool in applying the JANNAF liquid rocket thrust chamber performance prediction methodology. The development of a methodology that includes all aspects of rocket engine performance from analytical calculation to test measurements, that is physically accurate and consistent, and that serves as an industry and government reference is presented. Recent interest in rocket engines that operate at high expansion ratio, such as most Orbit Transfer Vehicle (OTV) engine designs, has required an extension of the analytical methods used by the TDK computer program. Thus, the version of TDK that is described in this manual is in many respects different from the 1973 version of the program. This new material reflects the new capabilities of the TDK computer program, the most important of which are described

The prime number theorem

Thesis (M.A.)--Boston University.In Chapter 1 of this thesis we give some elementary definitions and prove the following three theorems: 1.1 Every positive integer n greater than one can be expressed in the form n=p1p2...pk where each of the pi is a prime number. 1.2 Every integer n greater than one can be expressed in standard form in one and only one way. If we write n=(p1^a1)(p2^a2).....(pj^aj), where p1< p2 <...< pj and each ai is greater than 0, then n is expressed in standard form. 1.3 The number of prime numbers is infinite [TRUNCATED

Selecting children for head CT following head injury

OBJECTIVE: Indicators for head CT scan defined by the 2007 National Institute for Health and Care Excellence (NICE) guidelines were analysed to identify CT uptake, influential variables and yield. DESIGN: Cross-sectional study. SETTING: Hospital inpatient units: England, Wales, Northern Ireland and the Channel Islands. PATIENTS: Children (3 years were much more likely to have CT than those <3 years (OR 2.35 (95% CI 2.08 to 2.65)). CONCLUSION: Compliance with guidelines and diagnostic yield was variable across age groups, the type of hospital and region where children were admitted. With this pattern of clinical practice the risks of both missing intracranial injury and overuse of CT are considerable

Quorum sensing in \u3ci\u3eCandida albicans\u3c/i\u3e: farnesol versus farnesoic acid

Candida albicans is a clinically important dimorphic fungus that exhibits either a budding yeast or a mycelial-hyphal or pseudohyphal growth, depending on environmental conditions. The yeast-to-mycelia morphologic transition, which is generally regarded as an important virulence determinant, depends on the inoculum size of liquid cultures. The yeast form is favored when cultures are inoculated at \u3e 106 cells∙mL–1, whereas the mycelial form is favored at inoculum densities \u3c 106∙mL–1. Farnesoic acid (FA) and farnesol (FOH) are two related sesquiterpene quorum- sensing molecules that, upon accumulation, prevent the yeast-to-mycelial conversion. Oh et al. showed that C. albicans strain ATCC 10231 excretes FA, while Hornby et al. showed that C. albicans A72 and SC5314 excrete FOH. Subsequent work indicated that 10231 was the only isolate of C. albicans that fails to produce detectable FOH. Moreover, when tested on C. albicans A72, FA had only 3.2% of the hyphal-inhibitory activity relative to FOH. These observations raised two questions: 1., Do FOH and FA block mycelial development via the same molecular mechanism; and 2., What is the biochemical or physiologic difference in strain 10231 that underlies excretion of FA and not FOH? Do farnesol and farnesoic acid share a common mechanism of action? An apparent paradox in the regulation of hyphal morphogenesis by CaPho81p Why does C. albicans strain 10231 secrete farnesoic acid, while other C. albicans strains secrete farnesol