<p> The performance enhancement of stretch shortening cycle (SSe) contractions has been well documented in the literature. However, the majority of these studies have been performed either on gross human systems for multijointed movements, or in isolated animal muscle studies using in-vitro preparations. This study was designed to apply the principles used for these invitro animal studies to the human system, under conditions that would allow results to be directly associated with a specific muscle or muscle group. Previous investigations by Lynch (1992) and Benoit and Dowling (1995) have supported the use of muscle models to predict elbow flexor torque and sse performance enhancement. The purpose of this study was to use an EMG based muscle model to investigate the possible relationship between sse tasks at different frequencies of elbow flexion-extension and performance enhancement of the elbow flexor muscles. </p> <p> A Hill based muscle model was used to predict elbow flexor torque of seven healthy male subjects (23-40 years of age) under voluntary and stimulated contraction conditions. EMG of the elbow flexors and extensors was recorded from the biceps brachii and triceps respectively. Elbow flexor stimulation was done transcutaneously with a voltage equivalent to a 60% MVe torque; stimulation lasted four seconds at a frequency of 50 Hz. A simulated constant muscle activation torque was also derived from the muscle model for all trials. Externally measured torque was measured using a strain gauge located on a shaft situated along the axis of rotation of the elbow joint. A torque motor was used to drive the forearm (fastened to a manipulandum) at four frequencies of elbow flexion-extension (.58, 1.5, 2.4, and 3.3 Hz) over a range of 162 to 105 degrees of elbow extension. Non-SSe trials were performed at these same velocities and over the same range of motion. Torque was then integrated as a function of joint angle displacement to yield the work produced about the elbow. Passive work was subtracted from all trials. </p> <p> The results indicate that a significant increase in muscle work followed sse tasks as opposed to non-SSe tasks and this increased work was relatively highest at 2.4 Hz. Work about the elbow decreased with increasing frequency of movement for both sse and non-sse conditions. The simulated constant activation muscle model predicted work well for all trials and conditions, indicating muscle model accuracy. The EMG driven model predicted well for all non-SSe trials but significantly underestimated the work for sse tasks, suggesting a decrease in myoelectric activity. This decrease was evidenced by a decrease in average M-wave amplitude with increasing SSe velocity. This study indicates that the contractile component is directly involved in optimizing muscle work during sse tasks and that the performance enhancement of sse tasks may take place at the myofilament and cross-bridge level. </p> / Thesis / Master of Science (MSc)

Ultra Wideband (UWB) communication systems occupy large bandwidths with very low power spectral densities. This feature makes UWB channels highly rich in multipaths. To exploit the temporal diversity, a UWB receiver usually incorporates Rake reception. Each multipath in the channel carries just a fraction of the signal energy. This phenomenon dictates a Rake receiver with a large number of fingers to achieve good energy capture and output signal to noise ratio (SNR). Eventually, the Rake structure becomes very complex from analysis and design perspectives and incurs higher manufacturing cost. The first contribution of this thesis is to propose channel shortening or time domain equalization as a technique to reduce the complexity of the UWB Rake receiver. It is analyzed that most of the existing channel shortening equalizer (CSE) designs are either system specific or optimize a parameter not critical or even available in UWB systems. The CSE designs which are more generic and use commonly critical cost functions may perform poorly due to particular UWB channel profiles and related statistical properties. Consequently, the main contribution of the thesis is to propose several CSE designs to address the specific needs of UWB systems. These CSE designs not only exploit some general but also some UWB specific features to perform the task more efficiently. The comparative analysis of the proposed CSEs, some existing designs and the conventional Rake structures leads towards the conclusion. It is finally shown that the use of CSE at the receiver front end greatly simplifies the Rake structure and the associated signal processing.

Ultra Wideband (UWB) communication systems occupy large bandwidths with very low power spectral densities. This feature makes UWB channels highly rich in multipaths. To exploit the temporal diversity, a UWB receiver usually incorporates Rake reception. Each multipath in the channel carries just a fraction of the signal energy. This phenomenon dictates a Rake receiver with a large number of fingers to achieve good energy capture and output signal to noise ratio (SNR). Eventually, the Rake structure becomes very complex from analysis and design perspectives and incurs higher manufacturing cost. The first contribution of this thesis is to propose channel shortening or time domain equalization as a technique to reduce the complexity of the UWB Rake receiver. It is analyzed that most of the existing channel shortening equalizer (CSE) designs are either system specific or optimize a parameter not critical or even available in UWB systems. The CSE designs which are more generic and use commonly critical cost functions may perform poorly due to particular UWB channel profiles and related statistical properties. Consequently, the main contribution of the thesis is to propose several CSE designs to address the specific needs of UWB systems. These CSE designs not only exploit some general but also some UWB specific features to perform the task more efficiently. The comparative analysis of the proposed CSEs, some existing designs and the conventional Rake structures leads towards the conclusion. It is finally shown that the use of CSE at the receiver front end greatly simplifies the Rake structure and the associated signal processing.

No description available.

Many soft food materials, including vegetable shortening, exhibit complex rheological behaviour with properties that resemble those of a solid and a liquid simultaneously. The fundamental parameters used to describe the rheological response of vegetable shortening were obtained from uniaxial compression tests, including monotonic and cyclic compression, as well as creep and stress relaxation tests. The fundamental parameters obtained from the various compression tests were then used in two mechanical models (viscoelastic and elasto-visco-plastic) to predict the compression and conical indentation response of vegetable shortening. The accuracy of the two models was studied with the help of the commercially available finite element analysis software package Abaqus. It was determined that the viscoelastic model was not suitable for the prediction of the rheological response of shortening. On the other hand, the proposed elasto-visco-plastic model predicted with reasonable accuracy the uniaxial compression and indentation experimental response of vegetable shortening. / February 2009

Many soft food materials, including vegetable shortening, exhibit complex rheological behaviour with properties that resemble those of a solid and a liquid simultaneously. The fundamental parameters used to describe the rheological response of vegetable shortening were obtained from uniaxial compression tests, including monotonic and cyclic compression, as well as creep and stress relaxation tests. The fundamental parameters obtained from the various compression tests were then used in two mechanical models (viscoelastic and elasto-visco-plastic) to predict the compression and conical indentation response of vegetable shortening. The accuracy of the two models was studied with the help of the commercially available finite element analysis software package Abaqus. It was determined that the viscoelastic model was not suitable for the prediction of the rheological response of shortening. On the other hand, the proposed elasto-visco-plastic model predicted with reasonable accuracy the uniaxial compression and indentation experimental response of vegetable shortening.

Many soft food materials, including vegetable shortening, exhibit complex rheological behaviour with properties that resemble those of a solid and a liquid simultaneously. The fundamental parameters used to describe the rheological response of vegetable shortening were obtained from uniaxial compression tests, including monotonic and cyclic compression, as well as creep and stress relaxation tests. The fundamental parameters obtained from the various compression tests were then used in two mechanical models (viscoelastic and elasto-visco-plastic) to predict the compression and conical indentation response of vegetable shortening. The accuracy of the two models was studied with the help of the commercially available finite element analysis software package Abaqus. It was determined that the viscoelastic model was not suitable for the prediction of the rheological response of shortening. On the other hand, the proposed elasto-visco-plastic model predicted with reasonable accuracy the uniaxial compression and indentation experimental response of vegetable shortening.

Le contexte de ces travaux de thèse est la transmission dite faster-than-Nyquist (FTN). Cette technique propose d’augmenter l’efficacité spectrale en augmentant lerythme de transmission au-delà de la bande occupée par le signal émis, indépendamment de laconstellation choisie. Il a été montré que le FTN offre des taux d’information supérieurs à ceuxdes systèmes de Nyquist. Toutefois, le non respect du critère de Nyquist entraîne l’apparitiond’interférence entre symboles et des techniques de réception appropriées doivent être utilisées.La technique de réception dite channel shortening consiste à filtrer la séquence reçue puis àcalculer des probabilités symbole a posteriori approximatives à l’aide de l’algorithme BCJRen considérant une réponse de canal modifiée, de longueur réduite. Dans la littérature, enprésence d’information a priori, les filtres du récepteur channel shortening sont optimiséssous critère de maximisation de l’information mutuelle généralisée (IMG) en utilisant desméthodes numériques. Nous proposons dans ces travaux de thèse une solution analytiquepour l’ensemble des filtres channel shortening sous critère de maximisation de l’IMG lorsquele récepteur dispose d’information a priori. Nous démontrons ensuite que l’égaliseur au sens dela minimisation de l’erreur quadratique moyenne (MMSE) est un cas particulier de l’égaliseurchannel shortening. Dans le cadre de la turbo égalisation, nous étudions ensuite un estimateurpermettant d’obtenir l’information a priori à partir de l’information en sortie du décodeurcorrecteur d’erreurs. Finalement, nous évaluons les performances du système complet aveccodage correcteur d’erreurs sur canal à bruit additif blanc Gaussien. / In order to increase the spectral efficiency of digital communications systems,the faster-than-Nyquist (FTN) approach increases the symbol rate beyond the occupied bandwidthof the transmitted signal independently of the constellation type and size. It has beenshown that information rates of FTN systems are greater than those of Nyquist systems.However, the non-compliance of the Nyquist criterion causes inter-symbol interference to appearand therefore appropriate reception techniques must be used. At reception, the channelshortening approach consists on a receiving filter followed by a BCJR algorithm computingapproximate a posteriori symbol probabilities by considering a modified channel response ofreduced length. In the literature, the channel shortening receiving filters are chosen to maximizethe generalized mutual information (GMI). Such optimization is performed by usingnumerical optimization methods. In this PhD thesis, we propose a closed-form solution forall channel shortening filters considering the GMI maximization criterion. We show that theminimum mean square error (MMSE) equalizer is a particular case of the channel shorteningapproach. Within the frame of turbo equalization, we then study a suitable estimator allowingto obtain symbols a priori information from the information provided by the a decoder. Finally,we study the performance of the complete system with channel coding over an additivewhite Gaussian noise channel.

No description available.

<p>Two fundamental structural elements, basement architecture and basal decollement, play a significant role in the evolution of a tectonically active region. Using different approaches (field data, literature review and analogue models) this thesis demonstrates that these two elements affected the deformation style in the Zagros fold-thrust belt during Mesozoic extensional and Cenozoic contractional episodes. </p><p>Reassessment of available data suggests a new configuration for the basement to Zagros basin that consists of basement faults with three different trends. Complicated interrelationships of these basement faults divide the Zagros basin into two major basement blocks, active and passive. This model associated with geological evidence suggests that deformation in the basement due to the convergence between Arabia and Iran is not restricted to the Zagros Mountains but already involves a considerable part of the Arabian platform. However, deformation in the cover units is not only governed by the deformation in the basement, which are decoupled from each other by the Hormuz salt in many parts in the Zagros fold-thrust belt. </p><p>Geological evidence shows that there is a clear relationship between activity of the Hormuz structures and the basement faults in the Zagros basin. Extended analogue models indirectly show how Hormuz types of basal decollement associated with the opening of Neo-Tethys can control the distribution, number, width and geometry of faults, penetrative strain, and diapirism. Analogue models shortened from one-end show that the spatial distribution of the Hormuz salt in the Zagros belt map viscous and frictional decollements to the thin-skinned deformation. Shortening of the cover results in formation of partitioning of strain into transpressional zones, different topographic wedges and differential sedimentation of growth sediments along the Zagros belt. Model results supported by geological and geophysical data sets suggest that some of the faults previously attributed to basement could have developed above the initial lateral boundaries between viscous and frictional basal decollements.</p>