This paper puts forward two useful methods for self-adaptation of the mutation distribution -- the concepts of derandomization and cumulation. Principle shortcomings of the concept of mutative strategy parameter control and two levels of derandomization are reviewed. Basic demands on the self-adaptation of arbitrary (normal) mutation distributions are developed. Applying arbitrary, normal mutation distributions is equivalent to applying a general, linear problem encoding.

Lighter-than air vehicles are an attractive solution for many applications requiring a sustained airborne presence. The buoyancy force provides an energy-free form of lift, offering a non-traditional approach to long-duration missions for which traditional aircraft are not well-suited. Potential applications include roving or hovering surveillance and communication utilities for both military and commercial use, and a variety of remotesensing instruments for the scientific community. In particular, the Missile Defense Agency plans to utilize unmanned airships at high-altitudes to provide a long-duration missile defense presence around the coast-line of the United States. Operated at 70 kft, each of these “high altitude airships ” will fly above all regulated air-traffic for several months to years, will reside in a steady atmospheric regime, and will utilize solar energy to provide all required power. Two key objectives for this type of mission are that the unmanned airship have exceptionally long endurance, and that it operate with a sufficiently high-level of autonomy. In order to achieve these objectives, a robust guidance and control system is required, capable of auto-piloting and controlling the airship under an extremely wide range of atmospheric and wind conditions. The successful design of such a system first requires an accurate model of airship dynamics across its expansive flight envelope, and a representative model of the expected disturbances. The dynamics of an airship are markedly different from traditional aircraft, with significant effects from added mass and inertia, and a much higher sensitivity to wind. In this paper, a typical airship configuration is first sized to meet energy balance and mass constraints. The geometry of this configuration is then used to develop a general aerodynamic model for the airship. The equations of motion with added mass and inertia are developed, and the open-loop dynamics are analyzed across a range of flight conditions. Finally, control laws are designed for a single operating condition, and the closed-loop performance is presented across a range of velocities. I.

Iterative algorithms for numerical optimization in continuous spaces typically need to adapt their step lengths in the course of the search. While some strategies employ fixed schedules for reducing the step lengths over time, others attempt to adapt interactively in response to either the outcome of trial steps or to the history of the search process. Evolutionary algorithms are of the latter kind. One of the control strategies that is commonly used in evolution strategies is the cumulative step length adaptation approach. This paper presents a first theoretical analysis of that adaptation strategy by considering the algorithm as a dynamical system. The analysis includes the practically relevant case of noise interfering in the optimization process. Recommendations are made with respect to the problem of choosing appropriate popula- tion sizes.

Autonomous airships have gained a high degree of importance over the last decades, both theoretically as well and practically. This is due to their long endurance capability needed for monitoring, observation and communication missions. In this paper, a Multi-Objective Optimization approach (MOO) is followed for conceptual design of an airship taking aerody-namic drag, static stability, performance as well as the production cost that is proportional to the helium mass and the hull surface area, into account. Optimal interaction of the afo-rementioned disciplinary objectives is desirable and focused through the MOO analysis. Standard airship configurations are categorized into three major components that include the main body (hull), stabilizers (elevators and rudders) and gondola. Naturally, component sizing and positioning play an important role in the overall static stability and performance characteristics of the airship. The most important consequence of MOO analysis is that the resulting design not only meets the mission requirement, but will also be volumetrically optimal while having a desirable static and performance characteristics. The results of this paper are partly validated in the design and construction of a domestic unmanned airship indicating a good potential for the proposed approach.

Without a doubt, I have been blessed with amazing opportunities and extraordinary people in my life. The pursuit of this Ph.D. has been an endeavor that has pushed my limits in many ways. I am grateful for the opportunity and for the people who have helped me along the way. I would first like to extend my sincere gratitude to my advisor, Professor Yiyuan Zhao. When I met Yiyuan in 1995 as a student in his Flight Mechanics course, he immediately stood out to me as a deeply intelligent, thoughtful, and above all, compassionate person. Several years after I graduated, it was Yiyuan who encouraged me to pursue a Ph.D. His belief in me was contagious, and for that I am truly thankful. His guidance, insight and patience have been instrumental to my growth as a student, and are greatly appreciated. My thanks also go to Professor William Garrard. He has served as a second advisor to me throughout this program, and has been a mentor to me for many years. I sincerely appreciate his guidance, his sage advice, and the many opportunities that he has given. I extend my thanks to all of my committee members, including Professor Mihailo Jovanovic and Professor Demoz Gebre, for their time and valuable feedback. Thanks go to all of the people and organizations that contributed to the funding of

Dr.-Ing. M.Hepperle (AS)

an = coefficient for parabolic rear shape a1, a2, b1, b2, c1, c2, d1, d2 = coefficients of cubic splines that parameterize the center portion of the envelope CD = drag coefficient d = envelope diameter l = envelope length n = load per unit length along meridians, i.e., in warp direction n ’ = load per unit length along latitude circles, i.e., in weft direction pR = internal overpressure in the aerostat envelope R = radius of curvature of spherical front portion of envelope R1, R2 = radii of curvature and transverse curvature of an inflated structure XD = design vector for shape optimization I.

Stratospheric airships are lighter-than-air (LTA) vehicles that have the potential to pro-vide an extremely long-duration airborne presence at altitudes of 18-22 km. In this paper, we examine optimal ascent trajectories that utilize wind energy to achieve minimum-time and minimum-energy flights. The airship is represented by a three-dimensional point mass model, and the equations of motion include aerodynamic lift and drag, vectored thrust, added mass effects, and accelerations due to mass flow rate, wind rates, and Earth rota-tion. A representative wind profile is developed based on historical meteorological data and measurements. Trajectory optimization is performed by first defining an optimal control problem with both terminal and path constraints, then using direct collocation to develop an approximate nonlinear parameter optimization problem of finite dimension. Optimal ascent trajectories are determined using SNOPT for a variety of upwind, downwind, and crosswind launch locations. Results of extensive optimization solutions illustrate definitive patterns in the ascent path for minimum time flights across varying launch locations, and show that significant energy savings can be realized with minimum-energy flights, com-pared to minimum-time flights, given small increases in flight time. In addition, the effects of time-varying mass and Earth rotation are found to be comparable to the effects of wind rate, and are utilized in the optimal solutions.

Abstract — This focus of this research is to estimate the load acting on the envelope structure by using Fluid Structure Interaction (FSI). Envelope is a principle component of the Airship because it houses the gas which produces the lift and major components. In this paper envelope of airship with the payload of 7500 Kg is designed and analysed at velocities upto 300 Kmph to determine the loads acting on each member. This data is essential for structural design of the MAGLEV