Propagating plane harmonic waves through finite length plates of variable thickness using finite element techniques

An analysis is given using finite element techniques which addresses the propagaton of a uniform incident pressure wave through a finite diameter axisymmetric tapered plate immersed in a fluid. The approach utilized in developing a finite element solution to this problem is based upon a technique for axisymmetric fluid structure interaction problems. The problem addressed is that of a 10 inch diameter axisymmetric fixed plate totally immersed in a fluid. The plate increases in thickness from approximately 0.01 inches thick at the center to 0.421 inches thick at a radius of 5 inches. Against each face of the tapered plate a cylindrical fluid volume was represented extending five wavelengths off the plate in the axial direction. The outer boundary of the fluid and plate regions were represented as a rigid encasement cylinder as was nearly the case in the physical problem. The primary objective of the analysis is to determine the form of the transmitted pressure distribution on the downstream side of the plate

Transient natural convection flows in closed containers technical report no. 2

Measurements and calculations of natural flow convection and thermal stratification in closed container

Transient, laminar, free-convection heat and mass transfer in closed, partially filled, liquid containers technical report no. 1

Two-dimensional, laminar, transient, natural- convection heat and mass transfer in closed, partially filled liquid container

The use of satellite data in understanding and predicting convective and large-scale dynamical processes

Mesoscale convective processes and how they affect and interact with mid-latitude cyclones were studied. The ageostrophic and associated vertical motion field was calculated using a highly accurate iterative method of solving the semigeostrophic omega equation. The tendencies for convective destabilization in the 850-750 mb layer due to differential geostrophic and ageostrophic advection and differential moist adiabatic ascent, were found. The spectral models of the index oscillation, one barotropic and the other baroclinic, were developed. Theoretical and observational studies of cloud streets were conducted

Ephedrine requirements are reduced during spinal anaesthesia for caesarean section in preeclampsia

Part of the Portfolio Thesis by Geoffrey H. Sharwood-Smith: The inferior vena caval compression theory of hypotension in obstetric spinal anaesthesia: studies in normal and preeclamptic pregnancy, a literature review and revision of fundamental concepts, available at http://hdl.handle.net/10023/1815Background: Despite controversy over the haemodynamically safest blockade for caesarean section in women with severe preeclampsia, an increasing number of anaesthetists now opt for spinal anaesthesia. In a previous study we found that spinal compared to epidural anaesthesia offered an equally safe but more effective option for these patients. The current study was designed to compare the hypotension induced by spinal anaesthesia, as measured by ephedrine requirement, between 20 normotensive and 20 severely preeclamptic but haemodynamically stabilised women. Method: Standardised spinal anaesthesia was instituted and ephedrine was given in boluses of 6 mg if the systolic pressure fell >20% from the baseline, or if the patient exhibited symptoms of hypotension. Results: The mean ephedrine requirement of the normotensive group (27.9 ± 11.6 mg) was significantly greater (P < 0.01) than that of the preeclamptic group (16.4 ± 15.0 mg). Conclusion: This suggests that the hypotension induced by spinal anaesthesia in women with severe but haemodynamically stabilised preeclampsia, is less than that of normotensive patients.Publisher PD

Comparison of boiler feed pumps for cesium and potassium Rankine cycle systems

Comparison of electromagnetic and centrifugal pumps for cesium and potassium Rankine cycle system

Metal alloy resistivity measurements at very low temperatures

High speed, automated system accurately measures to approximately one percent in three minutes. System identifies materials having constant thermal or electric conductivity, predicts new material properties, develops alloys in accordance with desired specifications, and develops nondestructive devices for measuring precipitation hardening

The Effective Potential And Additional Large Radius Compactified Space-Time Dimensions

The consequences of large radius extra space-time compactified dimensions on the four dimensional one loop effective potential are investigated for a model which includes scalar self interactions and Yukawa coupling to fermions. The Kaluza-Klein tower of states associated with the extra compact dimensions shifts the location of the effective potential minimum and modifies its curvature. The dependence of these effects on the radius of the extra dimension is illustrated for various choices of coupling constants and masses. For large radii, the consequence of twisting the fermion boundary condition on the compactified dimensions is numerically found to produce but a negligible effect on the effective potential.Comment: 14 pages, LaTeX, 6 Postscript figure

Far Term Noise Reduction Roadmap for the NASA D8 and Single-Aisle Tube-And-Wing Aircraft Concepts

A portfolio of noise reduction technologies is applied to two advanced single-aisle class vehicle concepts in order to evaluate the prospects for these aircraft to meet the NASA Far Term noise goals, beyond 2035. TheNASAD8 (ND8) aircraft is an unconventional configuration with boundary-layer ingesting engines mounted in the aft dorsal location. The 160-passenger tube-and-wing (TW160) aircraft is a conventional configuration with podded engines located under the wing, which represents an incremental evolution of current design philosophies. The noise reduction technologies were chosen to be compatible with each aircrafts specific configuration requirements. The acoustic effects were predicted based on experimental and numerical studies, andwere incorporated into the prediction of total system noise usingNASAs research-level Aircraft NOise Prediction Program (ANOPP-Research). Results suggest that the unfavorable Propulsion Airframe Aeroacoustic (PAA) effects of the two aircraft considered here significantly limit their prospects of meeting NASAs Far Term noise goal, and that further development of the technology portfolio is key to ensuring future success in addressing the noise challenges for single-aisle class vehicles

Dynamics of moving bubbles in single and binary component systems

Dynamics of a single bubble moving in a quiescent liquid is analyzed for single and binary component systems. The transport of energy and/or mass at thermodynamic-phase equilibrium governs the dynamics of the bubble at its interface