This dissertation study the effectiveness of antenna switching diversity for orthogonal frequency division multiplexing (OFDM) systems such as in IEEE 802.11. One of the ways to exploit the multiple antenna configurations is to use antenna switching diversity. Antenna switching diversity is used in wireless systems to combat the effect of fading, as we can combine multiple independent copies of the same signal into a total signal with high quality. In this work, we implement and compare the performance of two systems, antenna switching diversity system and single-input single-output (SISO) system. We firstly study the performance of the antenna switching diversity system as we increases the number of antennas compared to the performance of signal-to-noise ratio (SNR) or gain of the system. The performance of antenna switching diversity is studied on several difference configurations such as receive diversity where there are multiple receive antennas, and transmit diversity where the there are multiple transmit antennas. The study is performed on eight (8) antenna switching, on either the transmit or receive side. The implementation of antenna switching diversity system shows that there are definite improvement on signal-to-noise ratio (gain) value compared to single-input single-output system signal-to-noise ratio (gain).

Although globally used in option pricing, the Black-Scholes model has not been able to reflect the evolution of stocks in the real world. A regime-switching model which allows jumps in the underlying asset prices and the parameters of the corresponding stochastic process is more accurate. We evaluate the analytical solution for pricing of European options under a two-state regime switching model. Both the convergence of the analytical solution and the feature of implied volatility are investigated through numerical examples. We develop a number of techniques for pricing American options by solving the system of partial differential equations in a general \mathcal{K}-state regime-switching model. The linear complementarity problem is replaced by either the penalty or the direct control formulations. With an implicit discretization, we compare a number of iterative procedures (full policy iteration, fixed point-policy iteration, and local American iteration) for the associated nonlinear algebraic equations. Specifically, a linear system appears in the full policy iteration which can be solved directly or iteratively. Numerical tests indicate that the fixed point-policy iteration and the full-policy iteration (using a simple iteration for the linear system), both coupled with a penalty formulation, results in an efficient method. In addition, using a direct solution method to solve the linear system appearing in the full policy iteration is usually computationally very expensive depending on the jump parameters. A Fourier transform is applied to the system of partial differential equations for pricing American options to obtain a linear system of ordinary differential equations that can be solved explicitly at each timestep. We develop the Fourier space timestepping algorithm which incorporates a timestepping scheme in the frequency domain, in which the frequency domain prices are obtained by applying the discrete Fourier transform to the spatial domain. Close to quadratic convergence in time and space is observed for all regimes when using a second order Crank-Nicolson scheme for approximation of the explicit solution of the ordinary differential equation.

The paper provides a model that assesses the set of complementary components of varying compatibility and its effect towards consumer adoption decisions. The smartphone market is a system good which utilizes the device and a set of compatible applications (apps). The amount of switching costs may vary depending upon the consumer’s decision to switch devices or across platforms. Analyzing the Android ecosystem, the process of custom ROMs (and rooting) and the large set of games, news, etc. apps justify the existence of device-specific and platform-specific apps. The model reinforces the findings of a survey conducted by UBS suggesting the retention rate (i.e. level of switch costs) of Apple users is higher than Android users. The retention among Android devices is much lower in comparison as well. The model observes that the product fragmentation and the interdependence of apps lead to the noticeably lower retention rates across Android devices and platforms.

<p>Switching networks are a common model for biological systems, especially</p><p>for genetic transcription networks. Stuart Kaufman originally proposed</p><p>the usefulness of the Boolean framework, but much of the dynamical </p><p>features there are not realizable in a continuous analogue. We introduce the notion</p><p>of braid-like dynamics as a bridge between Boolean and continuous dynamics and</p><p>study its importance in the local dynamics of ring and ring-like networks. We discuss</p><p>a near-theorem on the global dynamics of general feedback networks, and in the final</p><p>chapter study the main ideas of this thesis in models of a yeast cell transcription network.</p> / Dissertation

A State-Switched Absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. This dissertation considers the performance of the SSA for vibration suppression of continuous systems, specifically a beam and a plate. The SSA tuning frequencies and attachment point on the continuous body were optimized using a simulated annealing algorithm. It was found that an optimized SSA outperforms and optimized TVA at controlling vibrations of both a beam and a plate. These performance gains were also observed experimentally employing magneto-rheological elastomers to achieve a stiffness change. This dissertation also considers zero strain switching criteria and the maximum work extraction switching rule used by the SSA. The zero strain switching criteria ensures the system remains stable as no energy is added or released across a switch event. The maximum work extraction switching rule is designed to maximize the power dissipated by the absorber, but also guarantees minimization of the motion of the base to which the absorber is attached.

This study investigates the optical properties of the twisted-nematic liquid-crystals at oblique directions and their applications. A large difference in the phase retardation and the twisted angle of the TN-LC from different viewing directions occurs at the low voltage regime. The proposed viewing angle switching (VAS) panel is developed using this large optically anisotropic behavior of the TN-LC. The proposed VAS panel is only perceived clearly at normal and downward directions in a narrow viewing angle mode to ensure high privacy protection, it highly promising for mobile device applications.

In this study, a liquid-crystal display (LCD) with the capability of switchable viewing-angle is proposed. The contrast ratio of the LCD mainly depends on the transmittance of the bright state and the dark state. By using the improved structure of the pixel electrodes, the viewing angle of the LCD can be switched between the wide viewing-angle mode and the narrow-viewing angle mode. Based on the proposed three-electrode structure, the liquid-crystal orientation of the LCD is controlled to generate different light-leakage conditions at large viewing angles, thus, resulting in the switch of the viewing angle of the LCD. The proposed structure, which has the slim outline and low-cost of the LCD, is a simple way to control the viewing angle of the LCD. Potential applications for the protection of personal privacy are emphasized.

Radio Frequency (RF) Power Amplifiers are responsible for a considerable amount of the power consumption in the entire transmitter-receiver (transceiver) of modern communication systems. The stringent linearity requirements of multi-standard transceivers to minimize cross-talking effects makes Linear Power Amplifiers, particularly class A, the preferred choice in broadband transceivers. This linearity requirement coupled with the fact that the Power Amplifier operates at low transmit power during most of its operation makes the efficiency of the entire transceiver poor. The limited transceiver efficiency leads to a reduction in the battery life of battery operated portable devices like mobile phones; hence drastically limiting talk time. To alleviate this issue, several research groups propose solutions to improve PA power efficiency. However, these solutions usually have a low efficiency at low power and are mostly limited to narrow bandwidth applications. In this thesis, the efficiency of a class A Power amplifier in wideband wireless standards like WiMax is improved by dynamically controlling the bias current and supply voltage of the PA. An efficient supply modulator based on a switching regulator architecture is proposed for controlling the supply voltage. The switching regulator is found to be slew-limited by the bulky inductor and capacitor used to regulate the supply voltage. The proposed solution alleviates the slew rate limitation by adding a bang-bang controlled current source. The proposed supply modulator has an average power efficiency of 81.6 percent and is suitable for wireless standards with bandwidths up to 20MHz compared to the relatively lower efficiencies and bandwidths of state of the art modulators. A class-A PA is shown to promise an average power efficiency of 21.3 percent when the bias current is controlled dynamically and the supply voltage is varied using the proposed supply modulator. This is a significant improvement over the poor average efficiency of 1.06 percent for a fixed bias conventional linear class A PA. The project has been simulated using the TSMC 0.18 micrometer technology.

Thermal barrier coatings (TBCs) have become an important part of turbine technology by providing thermal protection to the underlying metallic components. These coatings are typically made from a zirconia-based ceramics which have a low thermal conductivity and thermal expansion coefficients similar to those of the superalloys. Early failure in these coatings is most often due to foreign object damage and erosion resulting in delamination and spallation. To protect against these types of failure, new materials with increased toughness are needed. There are two main toughening mechanisms in ceramics: transformation toughening, which is limited to low temperature applications and ferroelastic toughening which is accessible at all temperatures. Ferroelastic toughening occurs when the c-axis of the tetragonal grain undergoes reorientation under the application of an external stress. In this study, ferroelastic toughening is examined by Raman spectroscopy. It is shown that by using polarized confocal Raman spectroscopy one can not only observed the ferroelastic process, but also measure the parameters that control the increase in toughness observed. Ferroelastic toughening was observed in two ways in the 18mol% ceria stabilized zirconia (18CSZ) samples studied here. Samples were either exposed to indentation damage or uniaxial loading. In both of these cases maps of the ceramic surface were taken using Raman spectroscopy following loading and the relative intensities of the tetragonal peaks were analyzed. The resulting intensity profiles were used to monitor the reorientation of domains corresponding to ferroelastic toughening. Changes in domain orientation were observed that corresponded to the reorientation of domains along cracks as well as on a larger scale along those cracks. Domain reorientation was also observed under uniaxial loading and the stresses required for domain formation and movement were measured.

This thesis is concerned with the designing of an nth order adaptive integral variable structure derivative estimator (AIVSDE). The proposed estimator's scheme is in fact a modified and extended version of the existing AIVSDE. The new proposed AIVSDE can be used as a direct nth differentiator for a smooth signal which has n continuous and bounded derivatives. The adaptive algorithm is utilized for the switching gain to remove the requirement for a priori knowledge about the upper bound of the derivative of the input signal. The stability of the redesigned first order, the second order, and the nth order derivative's estimation is guaranteed by the proposed scheme. An example is demonstrated for showing the applicability of the proposed AIVSDE.