The work presented in this thesis is motivated by a need for an advanced understanding of the governing mechanisms for vibrations in complex structures. In order to obtain a simplified description of the complex structure with the dominant information of the structure enhanced, one removes some unimportant structural information from the description by identifying secondary contributing substructures and couplings, then describing them using simplified models. It is found that the secondary substructures are those substructures being required for their vibrational transmission characteristics only, and the secondary couplings are the weak couplings in the structure. Moreover, it is demonstrated that the transmission characteristics can be sufficiently described by using only the direct wave and the fIrst reflection in the structure, and the secondary coupling can be simplified as an idealised coupling. The procedure for establishing such a simplifIed description for the complex structure is illustrated by a two-element built-up structure. Finally, the efficiency of using such a simplifIed description to analyse the complex structure is demonstrated for two mechanical artefacts, one being a laboratory structure consisting of a cylindrical shell attached to a plate via two beams, and the other a full-scale aircraft - Eurofighter 2000.

Thesis (Ph. D.)--Rand Graduate School, 1999. / Includes bibliographical references (p. 120-122).

Recent developments in post-stall maneuverability and thrust vectoring have opened up new possibilities in the field of air combat maneuvering. High angle of attack maneuvers like the Cobra, Herbst Reversal, and Chakra demonstrate that today's cutting edge fighters are capable of exploiting the post-stall flight regime for very dynamic and unconventional maneuvers. With the development and testing of Unmanned Combat Aerial Vehicles, even greater maneuvering ability is expected. However, little work has been done to make use of this increased ability by optimizing a wide range of combat maneuvers. The goal of this thesis was to begin that process by finding several time-optimal air combat maneuvers that could be employed by current and future high performance fighter aircraft.

Thesis (Ph.D.)--RAND Graduate School, 1993. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): R.M. Howard, I.M. Ross. Includes bibliographical references (p. 215-217). Also available online.

Thesis (M.S.)--Air Force Institute of Technology, 2006. / "AFIT/GLM/ENS/06-08." "March 2006." Includes bibliographical references (leaves 217-219). Also available online via the Defense Technical Information Center website (http://stinet.dtic.mil/).

Thesis (M.B.A.)--Naval Postgraduate School, December 2003. / "MBA professional report"--Cover. Joint authors: Robert K. DeGuzman Jr., Thomas S. Fulford III, Jesse E. Porter Sr. Thesis advisor(s): Donald R. Eaton, Kevin R. Gue, Mary A. Malina. Includes bibliographical references (p. 71-73). Also available online.

No description available.

Study in the field of product development about Illuminating material for fire-fighter garments & others in the future / Program: Magisterutbildning i Applied Textile Management

Research into the improvement of the Aircraft ConceptualDesign process by the application of MultidisciplinaryOptimization (MDO) is presented. Aircraft conceptual designanalysis codes were incorporated into a variety of optimizationmethods including Orthogonal Steepest Descent (full-factorialstepping search), Monte Carlo, a mutation-based EvolutionaryAlgorithm, and three variants of the Genetic Algorithm withnumerous options. These were compared in the optimization offour notional aircraft concepts, namely an advanced multiroleexport fighter, a commercial airliner, a flying-wing UAV, and ageneral aviation twin of novel asymmetric configuration. Tobetter stress the methods, the commercial airliner design wasdeliberately modified for certain case runs to reflect a verypoor initial choice of design parameters including wingloading, sweep, and aspect ratio. MDO methods were evaluated in terms of their ability to findthe optimal aircraft, as well as total execution time,convergence history, tendencies to get caught in a localoptimum, sensitivity to the actual problem posed, and overallease of programming and operation. In all, more than a millionparametric variations of these aircraft designs were definedand analyzed in the course of this research. Following this assessment of the optimization methods, theywere used to study the issue of how the computer optimizationroutine modifies the aircraft geometric inputs to the analysismodules as the design is parametrically changed. Since thiswill ultimately drive the final result obtained, this subjectdeserves serious attention. To investigate this subject,procedures for automated redesign which are suitable foraircraft conceptual design MDO were postulated, programmed, andevaluated as to their impact on optimization results for thesample aircraft and on the realism of the computer-defined"optimum" aircraft. (These are sometimes called vehicle scalinglaws, but should not be confused with aircraft sizing, alsocalled scaling in some circles.) This study produced several key results with application toboth Aircraft Conceptual Design and MultidisciplinaryOptimization, namely:     MDO techniques truly can improve the weight and cost ofan aircraft design concept in the conceptual design phase.This is accomplished by a relatively small "tweaking" of thekey design variables, and with no additional downstreamcosts.In effect, we get a better airplane for free.     For a smaller number of variables (<6-8), adeterministic searching method (here represented by thefull-factorial Orthogonal Steepest Descent) provides aslightly better final result with about the same number ofcase evaluations     For more variables, evolutionary/genetic methods getclose to the best final result with far-fewer caseevaluations. The eight variables studied herein probablyrepresent the practical upper limit on deterministicsearching methods with today’s computer speeds.     Of the evolutionary methods studied herein, the BreederPool approach (which was devised during this research andappears to be new) seems to provide convergence in the fewestnumber ofcase evaluations, and yields results very close tothe deterministic best result. However, all of the methodsstudied produced similar results and any of them is asuitable candidate for use.     Hybrid methods, with a stochastic initial optimizationfollowed by a deterministic final "fine tuning", proved lessdesirable than anticipated.     Not a single case was observed, in over a hundred caseruns totaling over a million parametric design evaluations,of a method returning a local rather than global optimum.Even the modified commercial airliner, with poorly selectedinitial design variables far away from the global solution,was easily "fixed" by all the MDO methods studied.     The postulated set of automated redesign procedures andgeometric constraints provide a more-realistic final result,preventing attainment of an unrealistic "better" finalresult. Especially useful is a new approach defined herein,Net Design Volume, which can prevent unrealisticallyhigh design densities with relatively little setup andcomputational overhead. Further work in this area issuggested, especially in the unexplored area of automatedredesign procedures for discrete variables.