This thesis includes two topics. The first topic is a ZigBee transceiver used in 2.45 GHz band design. The second topic is a 2K/4K/8K multimode fast Fourier transformation ( FFT ) for DVB-H demodulators. The first topic includes simulations and hardware design. The chip is a physical layer design compliant with IEEE Std 802.15.4 standard, including a transmitter and a receiver for 2.45 GHz band. The measurement of the maximum power on silicon is about 731 £gW at 8 MHz. It is proved to be compliant with the low power consumption requirement specified by the standard. The second topic includes simulations and hardware design of an FFT for DVB-H demodulators. This processor is based on a pipeline architecture with radix-2, radix-22 and radix-23 computation element. We propose one sharing butterfly architecture to be used in the variable length FFT processor.

A new, high resolution, high precision and accuracy gravimetric geoid of Australia has been produced using updated data, theory and computational methodologies. The fast Fourier transform technique is applied to the computation of the geoid and terrain effects. The long, medium and short wavelength components of the geoid are determined from the OSU91A global geopotential model, 2'x2' (residual gravity anomalies in a 3 degrees cap and 1'x1' digital terrain model (DTM), respectively.Satellite altimeter gravity data have been combined with marine gravity data to improve the coverage of the gravity data, and thus the quality of the geoid. The best gridding procedure for gravity data has been studied and applied to the gravity data gridding. It is found that the gravity field of Australia behaves quite differently. None of the free-air, Bouguer or topographic-isostatic gravity anomalies are consistently the smoothest. The Bouguer anomaly is often rougher than the free-air anomaly and thus should be not used for gravity field gridding. It is also revealed that in some regions the topography often contains longer wavelength features than the gravity anomalies.It is demonstrated that the inclusion of terrain effects is crucial for the determination of an accurate gravimetric geoid. Both the direct and indirect terrain effects need to be taken into account in the precise geoid determination of Australia. The existing AUSGEOID93 could be in error up to 0.7m in terms of the terrain effect only. In addition, a series of formulas have been developed to evaluate the precision of the terrain effects. These formulas allow the effectiveness of the terrain correction and precision requirement for a given DTM to be studied. It is recommended that the newly released 9"x9" DTM could be more effectively used if it is based on 15"x15" grid.It is estimated from comparisons with Global ++ / Positioning System (GPS) and Australian Height Datum Data that the absolute accuracy of the new geoid is better than 33cm and the relative precision of the new geoid is better than 10~20cm. This new geoid can support Australian GPS heighting to third-order specifications.

Background:  As time moves on hardware is able to tackle heavier and more complex computations in real-time systems. This means that more realistic and stylistic environments can be computed. One of these environments is the ocean. To simulate ocean water in real-time, procedural methods such Gerstner waves and Fast Fourier Transformation (FFT) have been developed.    Objectives: The primary objective of this thesis is to compare two procedural methods that are designed to simulate realistic ocean water waves. Meanwhile, the goal of this thesis is for developers to gain an insight into these two methods used in order to simulate realistic ocean water waves. Additionally, it will also discuss advantages as well as disadvantages with both, which gives developers a thorough understanding of the most appropriate method for implementation.  Methods: FFT and Gerstner waves will be implemented in order to perform comparisons of resources, computation time and Video Random Access Memory (VRAM). The procedural methods will be calculated on the GPU and measured using DirectX 11 query interface. Lastly, the final step is to gather data from the CPU side, and store the metrics for time it took to render a frame and scalability of the displacement maps. \noindent\textbf{Results}.The profiling and experiments showed that FFT is more computationally intensive and requires more VRAM. For scalability, FFT also scales worse in terms of both computation time and VRAM usage. Conclusions: From the results we can conclude that FFT is more computationally heavy and requires more VRAM usage than Gerstner waves. In none of the tests did the computation time of Gerstner waves take longer than FFT. Depending on grid resolution, FFT took 4-16 times longer to compute than Gerstner. Even though Gerstner waves takes less time to compute, for smaller grids, less than 512x512, the difference is less than 0.2ms.

[Truncated abstract] This thesis presents three different methods to investigate flexural wave propagation and scattering, power flow and transmission efficiencies, and dynamic stress concentration and fatigue failures in structural dynamics. The first method is based on the acoustical wave propagator (AWP) technique, which is the main part described in this thesis. Through the numerical implementation of the AWP, the complete information of the vibrating structure can be obtained including displacement, velocity, acceleration, bending moments, strain and stresses. The AWP technique has been applied to systems consisting of a one-dimensional stepped beam, a two-dimensional thin plate, a thin plate with a sharp change of section, a heterogeneous plate with multiple cylindrical patches, and a Mindlin?s plate with a reinforced rib. For this Mindlin?s plate structure, through the comparison of the results obtained by Mindlin?s thick plate theory and Kirchhoff?s classical thin plate theory, the difference of theoretical predicted results is investigated. As part of these investigations, reflection and transmission coefficients, power flow and transmission efficiencies in a onedimensional stepped beam, and power flow in a two-dimensional circular plate structure, are studied. In particular, this technique has been successfully extended to investigate wave propagation and scattering, and dynamic stress concentration at discontinuities. Potential applications are fatigue failure prediction and damage detection in complex structures. The second method is based on experimental techniques to investigate the structural response under impact loads, which consist of the waveform measuring technique in the time domain by using the WAVEVIEW software, and steady-state measurements by using the Polytec Laser Scanning Vibrometer (PLSV) in the frequency domain. The waveform measuring technique is introduced to obtain the waveform at different locations in the time domain. These experimental results can be used to verify the validity of predicted results obtained by the AWP technique. Furthermore, distributions of dynamic strain and stress in both near-field (close to discontinuities) and far-field regions are investigated for the study of the effects of the discontinuities on reflection and transmission coefficients in a one-dimensional stepped beam structure. Experimental results in the time domain can be easily transferred into those in the frequency domain by the fast Fourier transformation, and compared with those obtained by other researchers. This PLSV technique provides an accurate and efficient tool to investigate mode shape and power flow in some coupled structures, such as a ribbed plate. Through the finite differencing technique, autospectral and spatial of dynamic strain can be obtained. The third method considered uses the travelling wave solution method to solve reflection and transmission coefficients in a one-dimensional stepped beam structure in the time domain. In particular, analytical exact solutions of reflection and transmission coefficients under the given initial-value problem are derived. These analytical solutions together with experimental results can be used to compare with those obtained by the AWP technique.

Dans ce travail de thèse, il s'agit essentiellement de déterminer les propriétés mécaniques et physiques linéaires effectives des composites dans lesquels l'interface entre deux phases n'est pas lisse mais très rugueuse. Une approche efficace pour surmonter les difficultés provenant de la présence de rugosités d'interface consiste d'abord à homogénéiser une zone d'interface rugueuse comme une interphase équivalente par une analyse asymptotique et ensuite à appliquer des schémas micromécaniques pour estimer les propriétés effectives en tenant en compte de la présence de l'interphase équivalente. L'objectif principal de ce travail est de développer cette approche dans un cadre général où la surface autour de laquelle l'interface oscille périodiquement et rapidement peut être courbée et les phénomènes physiques concernés peuvent être couplés. Pour atteindre cet objectif, la conduction thermique est premièrement étudiée comme un prototype des phénomènes de transport non couplés pour élaborer dans un cadre simple les éléments essentiels de notre approche. Cette étude, préliminaire mais très utile au vu de l'importance des phénomènes de transport, montre que des résultats généraux et compacts peuvent s'obtenir quand l'interface est ondulée dans une seule direction et que des méthodes numériques sont en général nécessaires dans le cas où l'interface oscille suivant deux directions. L'approche développée et les résultats obtenus pour la conduction thermique sont étendus d'abord à l'élasticité linéaire et ensuite aux phénomènes physiques linéaires couplés tels que la thermoélectricité et la piézoélectricité. Dans ces cas plus complexes, des résultats généraux sont obtenus pour les composites stratifiés avec les interfaces ondulées dans une seule direction et des méthodes numériques sont élaborées pour les composites dans lesquels les interfaces oscillent suivant deux directions / This work is essentially concerned with determining the effective linear mechanical and physical properties of composites in which the interface between two phases is not smooth but very rough. An efficient approach to overcome the difficulties arising from the presence of interfacial roughness is first to homogenize a rough interface zone as an equivalent interphase by an asymptotic analysis and then to apply micromechanical schemes to estimation of the effective properties while accounting for the equivalent interphase. The present work aims mainly to develop this approach in a general situation where the surface around which an interface oscillates periodically and quickly can be curved and the physical phenomena involved can be coupled. To achieve this goal, thermal conduction is first studied as a prototype of transport phenomena so as to elaborate key elements of our approach in a simple situation. This study,even preliminary but very useful in view of the importance of transport phenomena, shows that general and compact results can be obtained when the interface is corrugated in only one direction and that numerical methods are generally required when an interface is curved along two directions. The approach developed and the results obtained for thermal conduction are extended first to linear elasticity and then to linear coupled physical phenomena such as thermoelectricity and piezoelectricity. In these more complex cases, general results are obtained for composite laminates with interfaces oscillating in only one direction, and numerical methods are elaborated for composites in which the interfaces oscillate in two directions

The rapid advancements in semiconductor technology have led to constant shrinking of transistor sizes as per Moore's Law. Wireless communications is one field which has seen explosive growth, thanks to the cramming of more transistors into a single chip. Design of these systems involve trade-offs between performance, area and power. Fast Fourier Transform is an important component in most of the wireless communication systems. FFTs are widely used in applications like OFDM transceivers, Spectrum sensing in Cognitive Radio, Image Processing, Radar Signal Processing etc. FFT is the most compute intensive and time consuming operation in most of the above applications. It is always a challenge to develop an architecture which gives high throughput while reducing the latency without much area overhead. Next generation wireless systems demand high transmission efficiency and hence FFT processor should be capable of doing computations much faster. Architectures based on smaller radices for computing longer FFTs are inefficient. In this thesis, a fully parallel unrolled FFT architecture based on novel radix-4 engine is proposed which is catered for wide range of applications. The radix-4 butterfly unit takes all four inputs in parallel and can selectively produce one out of the four outputs. The proposed architecture uses Radix-4^3 and Radix-4^4 algorithms for computation of various FFTs. The Radix-4^4 block can take all 256 inputs in parallel and can use the select control signals to generate one out of the 256 outputs. In existing Cooley-Tukey architectures, the output from each stage has to be reordered before the next stage can start computation. This needs intermediate storage after each stage. In our architecture, each stage can directly generate the reordered outputs and hence reduce these buffers. A solution for output reordering problem in Radix-4^3 and Radix-4^4 FFT architectures are also discussed in this work. Although the hardware complexity in terms of adders and multipliers are increased in our architecture, a significant reduction in intermediate memory requirement is achieved. FFTs of varying sizes starting from 64 point to 64K point have been implemented in ASIC using UMC 130nm CMOS technology. The data representation used in this work is fixed point format and selected word length is 16 bits to get maximum Signal to Quantization Noise Ratio (SQNR). The architecture has been found to be more suitable for computing FFT of large sizes. For 4096 point and 64K point FFTs, this design gives comparable throughput with considerable reduction in area and latency when compared to the state-of-art implementations. The 64K point FFT architecture resulted in a throughput of 1332 mega samples per second with an area of 171.78 mm^2 and total power of 10.7W at 333 MHz.