This dissertation introduces a new multiscale stochastic finite element method (MSFEM) for determining the mechanical properties of polymer nanocomposites (PNC) consisting of polymers reinforced with single-wall carbon nanotubes (SWCNT). Obviously, reliable characterization of the various properties of nanomaterials such as PNC is indispensable in ...

The dynamics of offshore structures subjected to random waves is investigated. The load modeling and response analysis are conducted by using a new approach. The problems of the wave kinematics simulation and of the dynamic response determination are treated in an unified approach using filter techniques and the state space analysis. Some interesting ...

Dynamic analysis methods for computationally demanding systems are examined. Component Mode Synthesis methods are detailed and their limitations established. Decoupled analysis is offered as a solution for problems that traditional methods are incapable of addressing, such as systems with non-classical damping or geometric non-linearities. The ...

This thesis uses linear covariance analysis to model a landmark tracking camera for lunar navigation on manned missions during a loss of communication scenario. The research provides evidence that this method satisfies Crew Exploration Vehicle requirements for autonomous navigation for returning astronauts safely to Earth from lunar orbit. This study ...

In this thesis the impact of entangled and non-straight fibers in the determination of the effective elastic and thermal properties of polymer nanocomposite (PNC) is addressed. Most of the models in recent studies assume nanotubes to be well dispersed straight fibers with fixed size. Nonetheless experiments reveal that nanotube formation become wavy ...

The stationary response of a linear system excited by a stationary random process is considered. A previously developed approach is extended to determine both the even and odd integer order spectral moments of the system response. The approach offers an alternative to using the theory of complex residues to evaluate the integrals which represent the ...

Uncertainty is an inherent part of many physical systems. This is often ignored to simplify mathematical models thereby leading to a deterministic treatment of the system. Incorporation of the uncertainty into the model, particularly in the presence of strong correlation across scales is a difficult task for the conventional modeling techniques. This ...

A new algorithm is proposed that smoothly integrates the nonlinear estimation of the attitude quaternion using Davenport's q-method and the estimation of non-attitude states within the framework of an extended Kalman filter. A modification to the q-method and associated covariance analysis is derived with the inclusion of an a priori attitude estimate. ...

Many aerospace attitude control systems utilize a phase plane control scheme which includes nonlinear elements such as dead zone and ideal relay. Nonlinear control techniques such as pulse width modulation (PWM), describing functions, and absolute stability are implemented to determine stability. To evaluate phase plane control robustness, stability ...

Guidance methods for a powered descent planetary lander are examined. Several guidance laws are developed and analyzed including Apollo derived, modified Apollo, time efficient and fuel efficient methods. These laws are implemented using two different methods: Apollo approach, and real time. The equations of motion for an arbitrary planetary lander ...