Digital Commons Network^™

Effect Of Riblets On Pressure Recovery In A Straight-Walled Diffuser, Michael K. Reagan

Theses and Dissertations

The objective of this thesis was to investigate the effect of riblets on the pressure recovery in a straight-walled diffuser. Previous work has shown that riblets were effective in reducing the viscous drag over surfaces subjected to a turbulent boundary layer. More recently, riblets were shown to delay the flow separation within a subsonic, straight-walled diffuser by as much as 200%. The purpose of this investigation was to determine the effect on the pressure distribution within a diffuser that has had the flow separation point favorably altered by the application of riblets. Investigation results revealed that riblets not only delayed …

Investigation Of Fatigue Damage Mechanisms In A Metal Matrix Composite Under Elevated Temperature, Barry D. Portner

Theses and Dissertations

This study investigated the fatigue damage initiation and progression in SCS-6/Ti-15-3 under an environment of fatigue loading at isothermal temperature. This program included two parts. First, an 808 Ultimate Tensile Strength system was set up to accommodate testing at two frequencies of 2.0 and 0.0208 cps at a constant temperature of 427° C. Second, at intervals during the load cycle process, the test specimens were characterized by establishing damage parameters based on changing modulus of elasticity, average strain, strain range, and ultimate tensile strength. Damage progression was documented in the form of failure of the fiber-matrix interface, matrix cracking, fiber …

Robustness Of H2 And H∞ Design Techniques In The Design Of A Guided Missile Controller, Steven R. Kolbow

Theses and Dissertations

This work follows Capt. R.L. Riddle's 1989 thesis (ADA216147) which compared conventional, H₂ and H_∞ controlled guided missiles in simulated flyouts against an airborne target. The simulation results did not clearly demonstrate the H₂ and H_∞ controller advantages. In this study the missile model and simulation were refined. In addition to simulation runs, performance, noise attenuation, and μ (structural singular value) robustness analyses were conducted. Results showed areas where improvement was needed in the H₂ and H_∞ controllers used in the study. An H₂ and H_∞ controller redesign is recommended using the …

Computational Investigation Of Circulation Control Turbulence Modeling, T. Bryan Scruggs

Theses and Dissertations

A computational study of the turbulence model parameters and the effect on the flow field of a circulation control airfoil was conducted. A Beam- Warming algorithm with a modified Baldwin-Lomax turbulence model was used to solve the Navier-Stokes equations. A comparison between the effects of the Bradshaw constant on the flow field about the cylinder and the flow field about an airfoil were to be made. The lack of a steady 'converged' solution for the cylinder precluded the analysis of the flow field about a cylinder. For the airfoil, the separation point moves rearward and an enhanced vortex pattern is …

Fracture Toughness Of Unidirectional Fiber Reinforced Ceramic Composites In Mode Ii Utilizing Laser Interferometry, Joseph W. Truskowski

Theses and Dissertations

A laser interferometry technique to measure crack opening displacement was developed and applied to end notched flexure specimens of a Corning Glass Works 1723 glass matrix with silicon carbide fibers. The laser interferometer displacement gauge monitored the crack opening displacement (COD) at the location of a support while specimens were subjected to Mode II (forward shear) cracking at room temperature via three point bend tests on a standard Instron Compression machine. Vertical displacement was measured at the center of the test specimen using a linear variable differential transformer. Load verses displacement curves were generated for both the LVDT displacement and …

Micromechanical Modeling Of The Fiber/Matrix Interface Region In A Metal Matrix Composite, David D. Robertson

Theses and Dissertations

In order to develop reasonable analytical models and to better understand how the integrity of the fiber/matrix interface in high temperature titanium based metal matrix composites effects the overall transverse normal characteristics, a parametric study of various fiber/matrix interface conditions was performed. Analysis methods included both a simplified one-dimensional mathematical model and a finite element analysis using MSC/NASTRAN. First, both strong and weak interfacial bonds were examined. Subsequently, to provide for partial bonding, a model that used an elastic-plastic interphases zone between the fiber and matrix was examined.

Finite Element Investigation Into The Dynamic Instability Characteristics Of Laminated Composite Panels, Walter W. Taylor Jr.

Theses and Dissertations

Dynamic instability of a laminated composite panel subjected to a transverse load is studied. Up to cubic variations in the thickness coordinate are included in the inplane displacement field, and only the constant component is kept in the transverse displacement. The transverse shear strains retain only linear displacement terms and vary parabolically through the thickness. The complete quadratic displacement functions are included in the inplane strains. A 36 degree of freedom shell element is used to obtain numerical results. The static snap through load vs displacement curve, as well as the critical collapse load, is examined by invoking the Riks …

Thirty-Fifth Annual Madrigal Dinners, December 1990, Illinois State University

Madrigal Dinner Programs

Circus Room, Bone Student Center

A Strategic Market Game With A Mutual Bank With Fractional Reserves And Redemption In Gold (A Continuum Of Traders), Martin Shubik, Dimitrios P. Tsomocos

Cowles Foundation Discussion Papers

We utilize the strategic market game approach to analyze the role and function of a mutual bank with variable fractional reserves, redemption in gold and endogenous interest rate formation. We specify the conditions of enough money and its distribution. Using the continuum of traders model, we show existence and optimality for the case of no bankruptcy as well as for the case in which there exists the potentiality of bankruptcy. Finally, we analyze the relationship of the gearing ratio and the bankruptcy penalty with respect to the resulting equilibrium allocations.

Default And Bankruptcy In A Multistage Exchange Economy, Martin Shubik

Cowles Foundation Discussion Papers

Either lending must be secured or otherwise some form of default or bankruptcy rules are required to provide a disincentive against strategic default. When many time periods are involved, the mere specification of a penalty which is sufficient for one period of trade, is not sufficient. The complete specification of even a two period game requires that both the treatment of creditors (including seniority conditions) and the nature of the rehabilitation of the debtor must be specified. This paper explores these problems.

แนวทางจัดการศึกษาเพื่อพัฒนาเจตคติ ต่อวิชาชีพการพยาบาล, พวงรัตน์ บุญญานุรักษ์

Journal of Nursing Research, Innovation, and Health

No abstract provided.

ประสบการณ์ : ห้องผ่าตัดใน Portland, Oregon, U.S.A., ศัลยา ไผ่เข็มศิริมงคล

Journal of Nursing Research, Innovation, and Health

No abstract provided.

Pals Users' Group Newsletter 1990, University Of Alabama In Huntsville

PALS User Group Newsletters

No abstract provided.

Treatment Of Infected Pancreatic Necrosisby Open Drainage And Frequent Debridement, Chesada Sangsubhan, Taveesin Tanprayoon, Chanvit Tanphiphat

Chulalongkorn Medical Journal

No abstract provided.

Aural Gnathostomiasis, Pakpoom Supiyaphun, Prasert Sitthichareonchai, Amnuay Cutchavaree

Chulalongkorn Medical Journal

No abstract provided.

แฝดสยาม, สุทธิพร จิตต์มิตรภาพ

Chulalongkorn Medical Journal

No abstract provided.

Training And Development By Rolf P. Lyntum And Uday Pareek, New Delhi: Vistar Publication, 1990., Chidambara Iyer

IIMB Management Review

No abstract provided.

Self-Employment Programme For Rural Youth: The Role Of Non Governmental Organisations(Ngos), S N Sangita

IIMB Management Review

The Author offers a comparative analysis of govemment and non-government organisations in implementing rural development programme in four districts of Kamataka. He found a distinct variation in the performance of these organisations. The philosophies, strategies, and methods adopted by these organisations appeared to be mainly responsible for the effectiveness of the programme. The adoption of grass-root level planning, selection or operation in a smaller area, involvement of the people, supervision and commitment of its personnel in NGOs mainly contributed for the effective implementation of the progamme. On the other hand, top down approach, uniform policy with inappropriate administrative structures and …

Structure And Variability Of Recently Inserted Alu Family Members, Mark A. Batzer, Gail E. Kilroy, Pamela E. Richard, Tamim H. Shaikh, Trent D. Desselle, Carol L. Hoppens, Prescott L. Deininger

Faculty Publications

The HS subfamily of Alu sequences is comprised of a group of nearly identical members. Individual subfamily members share 97.7% nucleotide identity with each other and 98.9% nucleotide identity with the HS consensus sequence. Individual subfamily members are on the average 2.8 million years old, and were probably derived from a single source 'master' gene sometime after the human/great ape divergence. The recent Alu family member insertions provide a better image of the structure of Alu retroposons before they have had the opportunity to change significantly. All of the HS subfamily members are flanked by perfect direct repeats as a …

A High Power, Tunable, Arc-Lamp Pumped Nd-Doped Lanthanum-Hexaluminate Laser, Padetha Tin, Laird D. Schearer

Physics Faculty Research & Creative Works

An LNA (Nd-doped lanthanum-hex aluminate) crystal has been pumped with a cw, krypton arc lamp in a commercial Nd:YAG cavity. The cw output power greater than 6 W is obtained in a 28-cm long, plane mirror cavity. The free-running wavelength is near 1083 nm and has a width of about 0.8 nm. Inserting a 0.25 mm thick, uncoated solid etalon in the cavity permits the laser output to be continuously tuned from 1082 to 1084 nm by tilting the etalon. The laser bandwidth is reduced to below 0.016 nm. Over 3 W are obtained at the helium resonance transition. The …

Weak Localisation Theory For Lightly Doped Semiconductor Quantum Wires, G. Y. Hu, R. F. O'Connell

Faculty Publications

A weak localisation theory for a semiconductor quantum wire, which has a width of the order of the Fermi wavelength is presented. In the model the electronic motion is essentially one-dimensional and the localisation length L1 is much larger than the mean free path l, so that, in contrast to conventional theories a non-localised quantum wire with a total length Lproperties, the authors study the temperature dependence and the subbands effect of the weak localisation. They find that when (the phase coherent length) Lphi>L, the conductance of the quantum wire depends on L instead of Lphi, implying a temperature …

Dielectric Response Of A Quasi-One-Dimensional Electron System, G. Y. Hu, R. F. O'Connell

Faculty Publications

The dielectric response of a quasi-one-dimensional electron system is studied by including fluctuation effects (in the polarizability) and by using a recently derived analytic form for the electron-electron interactions. General forms for the polarizability matrices both for the intra- and inter-subband cases are presented. The generalized polarizability is analytic over the whole region of the wavevectors and rigorously retains the number neutrality. Various differences between the intra- and inter-subband cases for the polarizability and the dielectric matrix function are studied. The theory is used to study impurity screening and plasmon excitations in the presence of multi-subbands. The authors show that …

Oscillation Frequency In High-Gain Lasers, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The calculation of the oscillation frequency of a single-mode laser oscillator is examined systematically. Mode-pulling formulas are developed for a variety of laser systems, and the limitations of a standard approximation are explored.

Solitary Aerobic Exercise As A Treatment Of Unipolar Depressive Disorders In Women, Lisa Ann Romano-Neal

Masters Theses

The effects of solitary aerobic exercise on depressive symptoms were tested on four women diagnosed with unipolar depressive disorders. A multiple baseline design was employed. The subjects individually participated in uniform one hour aerobic workouts three times a week for five to eight weeks. Heart rate measures were monitored through the utilization of the physical working capacity test with the Monark 818E Professional Ergometer. Predicted volume oxygen uptake (VO2 max) measures at post-treatment did not increase in two of the four subjects when compared to pre-treatment VO2 max measures. The mean percentage of depressed adjectives endorsed showed minimal reductions on …

Wavelength (December 1990), Connie Atkinson

Wavelength

No abstract provided.

Pacific Review Nov/Dec 1990, Pacific Alumni Association

Pacific Magazine and Pacific Review

No abstract provided.

Update - December 1990, Loma Linda University Center For Christian Bioethics

Update

In this issue:

-- The euthanasia debate in the Netherlands: Biolegal, bioethical and biotheological considerations

[ In Vito Fertilization and Divorce ]
-- What Can We Learn?
-- A Legal Perspective
-- Some Thoughts Regarding Frozen Embryos and Devorce

Vol. 01, No. 04 (December 1, 1990)

Res Ipsa Loquitur

No abstract provided.

Reading: The Conferences, Jeanne M. Jacobson

Reading Horizons: A Journal of Literacy and Language Arts

National Council of Teachers of English, 80th Annual Convention, November, 1990 Many of the presentations at the annual convention of the National Council of Teachers of English, held in Atlanta in November, str'9ssed the theme of teachers educating themselves, and one another, through reflective practice, shared theory - and ongoing exercise of perceptive imagination. Our own minds need cultivation; our own practices need change; our own professional lives need to grow.

Dendrite Tip Radii In Directionally Solidified Pb-8.4-Atmospheric-Percent-Au, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

The cell/dendrite tip radii in directionally solidified Pb-8.4at.%Au have been investigated as a function of the growth speed and thermal gradient in the liquid at the tip. Dendrite growth models are not able to predict quantitatively the tip radii and tip compositions separately because of the occurrence of thermosolutal convection during growth. However, the relationship between the destabilizing solutal gradient, the stabilizing thermal gradient and the capillarity at the tip assumed using the ''marginal stability'' criterion is supported by the experimental data.