http://hdl.handle.net/2440/1082 Sat, 25 May 2013 16:50:49 GMT 2013-05-25T16:50:49Z http://hdl.handle.net/2440/77960 Title: A multi-layered tunable stepped-impedance resonator for liquid crystal characterization Author: Yaghmaee, Pouria; Karami Horestani, Ali; Bates, Bevan Douglas; Fumeaux, Christophe Abstract: The characterization of a tunable band-pass filter based on stepped-impedance resonator (SIR) is presented in this work. The designed filter uses a half-wavelength resonator patch above a multi-layer substrate, with liquid crystal as its central layer, making it continuously tunable at frequencies around S-band. Two liquid crystal samples are considered for three different approaches: lumped-element circuit simulation, full-wave electromagnetic simulations and prototype measurements. The results demonstrate the possibility of using a simple lumped-element circuit simulation for rapid calculation of the performances of liquid crystal devices at microwave frequencies. Sat, 31 Dec 2011 13:30:00 GMT http://hdl.handle.net/2440/77960 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77946 Title: A comparative study of volumetric vs. subcell modeling of thin-wire structures in FVTD Author: Jeffrey, Ian; Lo Vetri, Joe; Fumeaux, Christophe Abstract: Unstructured time-domain solvers such as the finitevolume time-domain method have the capability to directly model very fine geometric features. Nevertheless, subcell thinwire models are beneficial for reducing the number of volumetric cells. In this work, we compare broadband network parameter extraction when wires are modeled by volumetric discretization and fed by appropriately selected port models versus wires modeled using a mesh-independent thin-wire model. The results of these methods are compared to measurements for broadband S-parameter extraction of a simple monopole antenna. Sat, 31 Dec 2011 13:30:00 GMT http://hdl.handle.net/2440/77946 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77942 Title: Observer-based reliable control for discrete time systems: an average dwell time approach Author: Du, Dongsheng; Jiang, Bin; Shi, Peng; Mao, Zehui Abstract: This paper deals with the problem of reliable control for discrete time systems with actuator failures. The actuator is assumed to fail occasionally and can recover over a time interval. During the time of suffering failures, the considered closed-loop system is assumed unstable. Using an average dwell time method and under the condition that the activation time ratio between the system without actuator failures and the system with actuator failures is not less than a specified constant, an observer-based feedback controller is developed in terms of linear matrix inequalities such that the resulting closed-loop system is exponentially stable. An example is included to demonstrate the effectiveness of the proposed approach. Sat, 31 Dec 2011 13:30:00 GMT http://hdl.handle.net/2440/77942 2011-12-31T13:30:00Z http://hdl.handle.net/2440/77936 Title: Backstepping control in vector form for stochastic Hamiltonian systems Author: Wu, Zhaojing; Cu, Mingyue; Shi, Peng Sat, 31 Dec 2011 13:30:00 GMT http://hdl.handle.net/2440/77936 2011-12-31T13:30:00Z