1,318 research outputs found
Implications of stress and coping mechanisms in the superintendency
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on June 8, 2009)Vita.Thesis (Ed. D.) University of Missouri-Columbia 2008.The purpose of this mixed method design study was to add to the body of knowledge about stress and coping mechanisms by examining perceptions of superintendents stress by comparing perceptions of frequency of stress and what, if any, coping mechanisms were engaged. Moreover, the study sought to identify any significant differences between the frequency of stressors by gender and coping mechanisms utilized by female and male leaders. This study focused on qualities of coping mechanisms and their effectiveness and what type of support was provided by the school district. Study findings revealed that there is a statistical difference between the types of coping mechanisms utilized and effectiveness between male and female superintendents. Qualitative findings established the school district personnel provided no known support to superintendents in developing stress management skills and coping strategies. Other themes that arose from the study included; barriers in the perception of stress as it relates to gender, inconsistencies in the leaders ability to take time off, while superintendents agreed the school board is the predominant influencing factor, and the need for professional development programs.Includes bibliographical reference
Characterization of an 8-cm Diameter Ion Source System
Results of tests characterizing an 8-cm diameter ion source are presented. The tests were conducted in three separate vacuum test facilities at the University of Alabama-Huntsville, Colorado State University, and L3 Communications' ETI division. Standard ion optics tests describing electron backstreaming and total-voltage-limited impingement current behavior as a function of beam current were used as guidelines for selecting operating conditions where more detailed ion beam measurements were performed. The ion beam was profiled using an in-vacuum actuating probe system to determine the total ion current density and the ion charge state distribution variation across the face of the ion source. Both current density and ExB probes were utilized. The ion current density data were used to obtain integrated beam current, beam flatness parameters, and general beam profile shapes. The ExB probe data were used to determine the ratio of doubly to singly charged ion current. The ion beam profile tests were performed at over six different operating points that spanned the expected operating range of the DAWN thrusters being developed at L3. The characterization tests described herein reveal that the 8-cm ion source is suitable for use in (a) validating plasma diagnostic equipment, (b) xenon ion sputtering and etching studies of spacecraft materials, (c) plasma physics research, and (d) the study of ion thruster optics at varying conditions
Multiple Sample Cryostat for the Determination of Superconductor Properties
Cryostats which are currently used to characterize the properties of superconductors between 4 K and 100 K are primarily single sample devices. The purpose of this paper is to present an instrument design which can hold up to five (5) one cm. diameter samples at a stable temperature (+ /-0.1K) within the above range specified while measurements of the sample properties are made
A Four-Winged Domestic Fowl
Variations in structure in any given species of animal, range from the most minute structures that can be examined by microscopic or other technical means, to the gross items that are easily discernable with the unaided eye. Such variations are of extreme interest to the biologist and serve to forcibly remind him of the vast range of variations possible in any given species. The report on the present specimen seeks, not to present it as a monstrosity of the strange and unusual type, but rather to relate it in some measure with the usual development in chicks and to some of the rather obvious problems involved
Crew procedures development techniques
The study developed requirements, designed, developed, checked out and demonstrated the Procedures Generation Program (PGP). The PGP is a digital computer program which provides a computerized means of developing flight crew procedures based on crew action in the shuttle procedures simulator. In addition, it provides a real time display of procedures, difference procedures, performance data and performance evaluation data. Reconstruction of displays is possible post-run. Data may be copied, stored on magnetic tape and transferred to the document processor for editing and documentation distribution
Numerical Determination of Critical Conditions for Thermal Ignition
The determination of ignition or thermal explosion in an oxidizing porous body of material, as described by a dimensionless reaction-diffusion equation of the form .tu = .2u + .e-1/u over the bounded region O, is critically reexamined from a modern perspective using numerical methodologies. First, the classic stationary model is revisited to establish the proper reference frame for the steady-state solution space, and it is demonstrated how the resulting nonlinear two-point boundary value problem can be reexpressed as an initial value problem for a system of first-order differential equations, which may be readily solved using standard algorithms. Then, the numerical procedure is implemented and thoroughly validated against previous computational results based on sophisticated path-following techniques. Next, the transient nonstationary model is attacked, and the full nonlinear form of the reaction-diffusion equation, including a generalized convective boundary condition, is discretized and expressed as a system of linear algebraic equations. The numerical methodology is implemented as a computer algorithm, and validation computations are carried out as a prelude to a broad-ranging evaluation of the assembly problem and identification of the watershed critical initial temperature conditions for thermal ignition. This numerical methodology is then used as the basis for studying the relationship between the shape of the critical initial temperature distribution and the corresponding spatial moments of its energy content integral and an attempt to forge a fundamental conjecture governing this relation. Finally, the effects of dynamic boundary conditions on the classic storage problem are investigated and the groundwork is laid for the development of an approximate solution methodology based on adaptation of the standard stationary model
Three-Dimensional Numerical Modeling of Magnetohydrodynamic Augmented Propulsion Experiment
Over the past several years, NASA Marshall Space Flight Center has engaged in the design and development of an experimental research facility to investigate the use of diagonalized crossed-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In support of this effort, a three-dimensional numerical MHD model has been developed for the purpose of analyzing and optimizing accelerator performance and to aid in understanding critical underlying physical processes and nonideal effects. This Technical Memorandum fully summarizes model development efforts and presents the results of pretest performance optimization analyses. These results indicate that the MHD accelerator should utilize a 45deg diagonalization angle with the applied current evenly distributed over the first five inlet electrode pairs. When powered at 100 A, this configuration is expected to yield a 50% global efficiency with an 80% increase in axial velocity and a 50% increase in centerline total pressure
Computer programs for calculating two-dimensional potential flow in and about propulsion system inlets
Incompressible potential flow calculations are presented that were corrected for compressibility in two-dimensional inlets at arbitrary operating conditions. Included are a statement of the problem to be solved, a description of each of the computer programs, and sufficient documentation, including a test case, to enable a user to run the program
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