Acoustically, teleost swimbladders have been considered resonant underwater bubbles. Contrary results indicating that bladders are tuned less sharply than such a bubble have been explained by damping of surrounding fish tissue. Recent findings in toadfish and weakfish, however, suggest that the bladder is a highly damped structure and that the frequency of the fish sounds is deternlined as a forced response to sonic muscle movement rather than by resonance of the bladder. In this study I examined acoustics and material properties of swimbladders in Tilapia (an auditory generalist) and the channel catfish (an auditory specialist). The swimbladder was struck with a piezoelectric impact hammer. Amplitude and timing characteristics of bladder sound and displacement were compared for strikes of different amplitudes. Most of the first cycle of sound occurs during swimbladder compression, indicating that the bladder rapidly contracts and expands as force increases during the strike. Harder hits are shorter in duration generate a similar displacement duration with an increasing number of shorter cycles and a 12-15 dB increase in sound amplitude. The frequency spectrum is broad, and the dominant frequency is driven by the strike and not the natural frequency of the bladder. The displacement waveform varies between species catfish exhibit a greater structural stiffness and lower amplitude movement and higher sound amplitude for an equivalent hammer strike. Material properties (peak load, stress, strain, Young's modulus), fiber direction (catfish only), and structural stiffiless of bladders exhibit various patterns suggesting that the bladder walls are not uniform structures. Additionally thickness varies regionally. Notably Young's modulus in both species is similar despite large difference in stress and strain. The modulus of catfish bladder increased 1600-fold when dried. Finally the bladder of both species had a high water content averaging about 70%. These data suggest that viscous damping caused by water in the bladder wall is a major factor responsible for acoustic properties of the teleost swimbladder.

No description available.

The estimation of the frequency and phase of a complex exponential in additive white Gaussian noise (AWGN) is a fundamental and well-studied problem in signal processing and communications. A variety of approaches to this problem, distinguished primarily by estimation accuracy, computational complexity, and processing latency, have been developed. One class of approaches is based on the Fast Fourier Transform (FFT) due to its connections with the maximum likelihood estimator (MLE) of frequency. This thesis compares several FFT-based approaches to the MLE in terms of their estimation accuracy and computational complexity. While FFT-based frequency estimation tends to be very accurate, the computational complexity of the FFT and the latency associated with performing these computations after the entire signal has been received can be prohibitive in some scenarios. Another class of approaches that addresses some of these shortcomings is based on linear regression of samples of the instantaneous phase of the observation. Linear- regression-based techniques have been shown to be very accurate at moderate to high signal to noise ratios and have the additional benefit of low computational complexity and low latency due to the fact that the processing can be performed as the samples arrive. These techniques, however, typically require the computation of four-quadrant arctangents, which must be approximated to retain low computational complexity. This thesis proposes a new frequency and phase estimator based on simple estimates of the zero-crossing times of the observation. An advantage of this approach is that it does not require arctangent calculations. Simulation results show that the zero-crossing frequency and phase estimator can provide high estimation accuracy, low computational complexity, and low processing latency, making it suitable for real-time applications. Accordingly, this thesis also presents a real-time implementation of the zero-crossing frequency and phase estimator in the context of a time-slotted round-trip carrier synchronization system for distributed beamforming. The experimental results show this approach can outperform a Phase Locked Loop (PLL) implementation of the same distributed beamforming system.

A partir d’une sociologie de l’action organisée attentive à la mise en œuvre de la politique de la Fédération Française de Tennis (FFT) dans et par ses unités territoriales, notre travail analyse les effets induits par le double processus de « déconcentralisation » et de professionnalisation plus particulièrement sur la gouvernance de ces organisations. Nous montrons ici que le siège FFT, face aux menaces qui pèsent sur le tournoi « Roland-Garros » et afin de préserver son modèle, a engagé une transformation de la territorialisation de son action. Ayant défini à ce titre un nouveau mode de régulation entre les différentes organisations qui la composent, un changement est désormais à l’œuvre au sein des ligues régionales et des comités départementaux. Dans la première partie, nous montrons comment le siège FFT se sert du contexte économique pour faire évoluer sa gouvernance et pour mettre en œuvre un nouveau mode de pilotage de ses unités territoriales. La deuxième partie analyse, ensuite, le développement de cette action fédérale qui se veut plus processuelle que contractuelle, action marquée, en outre, par le caractère inter-organisationnel donnée à la résolution des problèmes de gouvernance territoriale afin de gagner en flexibilité et cohérence. Enfin, dans la troisième partie, nous relativisons les effets des nouvelles règles fédérales en démontrant que la FFT a finalement pleinement profité de l’antériorité de la dynamique de changement déjà à l’œuvre au sein des ligues même si celle-ci se déployait avec de fortes différenciations temporelles et fonctionnelles selon les territoires. / Our study is based on the sociological side of the numerous organized actions dealing with the implementation of the politics of the French Tennis Federation (FFT) among and throughout its territorial units. The goal of this research was to analyze the effects engendered by the double process of devolution –the passing of power- and professionalization, especially on the governance of these organized actions.We wanted here to show that the French Tennis Federation’s head office, confronted with the well-known threats concerning the French Grand Slam Roland Garros and in the objective of preserving its model of functioning, has engaged into a transformation of the territorialisation of its actions. To this end, it defined a new model of regulation between the different organizations it is composed of. This change is now being implemented within the regional tennis leagues and departmental committees.First, we will show how the French Tennis Federation’s head office is using the economic context in order to make its governance better and to implement a new model of management of its territorial units. Then, the second part is an analysis of the development of this federal action that is more of a process than a contract. Furthermore, this action is marked by the inter-organizational nature given to the manner of solving problems of territorial governance so that the French Tennis Federation can become more flexible and consistent. In the last part of the dissertation, we try to put the effects of these new federal rules into perspective. This is done by showing that the French Tennis Federation has in fact largely taken advantage of the changing dynamics that was already being put into action among the regional tennis leagues, even if this dynamics was highly different in matters of time and functioning depending on the territories concerned.

<p>Today radars are used to measure the distance to almost anything. It is used to determine the position of airplanes as well as the level of an oiltank. To achieve high precision in level gauging radars high quality components are demanded. This makes them expensive.</p><p>In this project we evaluate the possibility to use relatively cheap components, used in radio communication, to measure distances with an OFDM-modulated signal. The components are cheap due to large production volumes rather than low performance.</p><p>To do this we started with working out the theory needed for length estimation. At our disposal we had the SDR SFF Development Platform from Lyrtech. A simulation model of the platform was built in MatLab. This model was used to verify the theory developed. Finally our algorithms was implemented on the development platform.</p><p>Both simulations and real life measurements show that OFDM can be used to measure distances. Even though the hardware used in this project is not dedicated for this application we managed to perform measurements with good accuracy at short range. We believe that with more suitable hardware OFDM-radars will be able to compete with todays high end level gauging radars at all ranges.</p> / <p>Nu för tiden används radar för att mäta avstånd i en rad olika sammanhang. Det används till allt från att bestämma positionen på flygplan till att mäta nivån i oljetankar. För att uppnå den höga precision som krävs vid nivåmätning ställs höga krav på de ingående komponenterna. Detta gör att radarn blir dyr.</p><p>I detta examensarbete utvärderar vi möjligheten att använda relativt billiga komponenter, som används inom radiokommunikation, för att mäta avstånd med hjälp av en OFDM-modulerad signal. Dessa komponenter är billiga till följd av stora tillverkningsvolymer, inte för att de är dåliga.</p><p>Till att börja med tog vi fram den teori som behövdes för att skatta avstånd. Till vårt förfogande hade vi Lyrtechs SDR SFF Developmemt Platform. En simuleringsmodell av platformen gjordes i MatLab vilken användes för att verifiera teorin. Slutligen implementerades algoritmerna på utvecklingsplattformen.</p><p>Både simuleringar och riktiga mätningar visar att OFDM kan användas för att mäta avstånd. Trots att hårdvaran som användts under examensarbetet inte är anpassad för avståndsmätning blev mätresultaten goda för korta avstånd. Vi är övertygade om att med en, för ändamålet, mer anpassad hårdvara kommer en OFDM-radar upppnå samma precision som dagens högpresterande nivåmätareäven för längre avstånd.</p>

<p>The advanced signal processing systems of today require extreme data throughput and low power consumption. The only way to accomplish this is to use parallel processor architecture.</p><p>The aim of this thesis was to evaluate the use of parallel processor architecture in baseband signal processing. This has been done by implementing three demanding algorithms in LTE on Ambric Am2000 family Massively Parallel Processor Array (MPPA). The Ambric chip is evaluated in terms of computational performance, efficiency of the development tools, algorithm and I/O mapping.</p><p>Implementations of Matrix Multiplication, FFT and Block Interleaver were performed. The implementation of algorithms shows that high level of parallelism can be achieved in MPPA especially on complex algorithms like FFT and Matrix multiplication. Different mappings of the algorithms are compared to see which best fit the architecture.</p>

Hypergoemetric Series are very important in mathematics and come up regularly when dealing with the precise definitions of constants such as <i>e</i>, &pi; and Apery's constant &sigmaf;(3). The evaluation of such series to high precision is traditionally done with multiple divisions, multiplications and factorials, which all takes a long time to compute, especially when the computation is done on a single machine. The interest lies in performing this computation in parallel and in a distributed fashion. In this thesis, we present a simple distributed toolkit for doing such computations by splitting the problem into smaller sub-problems, solving these sub-problems in parallel on distributed machines and then combining the result at the end. Our toolkit takes care of all the networking for the user; connectivity, dropped connections, management of the Clients and the Server. All the user has to provide is the definition of the problem; how to split the problem into sub-problems, how to solve the sub-problems and finally how to combine the sub-problems and produce a result. The toolkit records timings for computation as well as for communication. What is different about our application is that all the code is written in Java (which is completely machine independent) and all the Clients are Java Applets. This means that having a web browser in enough to take part in the computation when it is distributed over the internet. We are almost guaranteed that every computer on the internet has a web browser. The Java Plug-in (if unavailable) can easily be downloaded from Sun's web site. We present a comparison between Java's native BigInteger library and an FFT based Integer Library written by R. Howell of University of Kansas. This study is important since we are doing computations with very large integers. To test our system, we evaluate <i>e</i> to different number of digits of precision and show that our system truly works and is easy for anyone to use.

In digital communication systems, satellites give us world wide services. These satellites should effectively use the available bounded frequency spectrum and, therefore, to carry out flexible frequency-band reallocation (FFBR), on-board signal processing implementation on FFBR network is needed. In the future, to design desired dynamic communication systems, very flexible digital signal processing structures will be needed. The hardware, in the system, shall not be changed as simple changes in the software will be made. The purpose of this thesis is to implement an N-channel FFBR network, where N=20. A 20-channel FFBR network consists of different blocks, e.g., DFT, IDFT, complex multipliers, input/output commutators and polyphase components. The whole 20-channel FFBR network will be implemented in VHDL. In a 20-channel FFBR network, it is a 20-point FFT/IFFT required. This 20-point FFT/IFFT is built by a combination of radix-4 and radix-5 butterflies. The Cooley-Tukey FFT algorithm is chosen to build the 20-point FFT/IFFT. The main aim is to build 20-point FFT/IFFT. There are 20 complex multipliers before the IFFT block and 20 complex multipliers after the IFFT block. In the same way, 20 complex multipliers are used before the FFT block and 20 complex multipliers are used after the FFT block. At the input/output to this FFBR network, 20 FIR filters (polyphase components) are used, respectively.

Hypergoemetric Series are very important in mathematics and come up regularly when dealing with the precise definitions of constants such as <i>e</i>, &pi; and Apery's constant &sigmaf;(3). The evaluation of such series to high precision is traditionally done with multiple divisions, multiplications and factorials, which all takes a long time to compute, especially when the computation is done on a single machine. The interest lies in performing this computation in parallel and in a distributed fashion. In this thesis, we present a simple distributed toolkit for doing such computations by splitting the problem into smaller sub-problems, solving these sub-problems in parallel on distributed machines and then combining the result at the end. Our toolkit takes care of all the networking for the user; connectivity, dropped connections, management of the Clients and the Server. All the user has to provide is the definition of the problem; how to split the problem into sub-problems, how to solve the sub-problems and finally how to combine the sub-problems and produce a result. The toolkit records timings for computation as well as for communication. What is different about our application is that all the code is written in Java (which is completely machine independent) and all the Clients are Java Applets. This means that having a web browser in enough to take part in the computation when it is distributed over the internet. We are almost guaranteed that every computer on the internet has a web browser. The Java Plug-in (if unavailable) can easily be downloaded from Sun's web site. We present a comparison between Java's native BigInteger library and an FFT based Integer Library written by R. Howell of University of Kansas. This study is important since we are doing computations with very large integers. To test our system, we evaluate <i>e</i> to different number of digits of precision and show that our system truly works and is easy for anyone to use.

The high amount of scientific and communications data produced by low earth orbiting satellites necessitates economical methods of communication with these satellites. A volumetric phased array for demonstrating horizon-to-horizon electronic tracking of the NASA satellite EO-1 was developed and demonstrated. As a part of this research, methods of optimizing the elemental antenna as well as the antenna on-board the satellite were investigated. Using these optimized antennas removes the variations in received signal strength that are due to the angularly dependent propagation loss exhibited by the communications link. An exhaustive study using genetic algorithms characterized two antenna architectures, and included optimizations for radiation pattern, bandwidth, impedance, and polarization. Eleven antennas were constructed and their measured characteristics were compared to those of the simulated antennas. Additional studies were conducted regarding the optimization of aperiodic arrays. A pattern-space representation of volumetric arrays was developed and used with a novel tracking algorithm for these arrays. This algorithm allows high-resolution direction finding using a small number of antennas while mitigating aliasing ambiguities. Finally, a method of efficiently applying multiple beam synthesis using the Fast Fourier Transform to aperiodic arrays was developed. This algorithm enables the operation of phased arrays combining the benefits of aperiodic element position with the efficiency of FFT multiple beam synthesis. Results of this research are presented along with the characteristics of the volumetric array used to track EO-1. Experimental data and the interpretations of that data are presented, and possible areas of future research are discussed.