In this thesis, several computationally-efficient approximate soft demodulation schemes are developed for multiple-input multiple-output (MIMO) communication systems. These soft demodulators are designed to be deployed in the conventional iterative receiver ('turbo') architecture, and they are designed to provide good performance at substantially lower computational cost than that of the exact soft demodulator. The proposed demodulators are based on the principle of list demodulation and can be classified into two classes, according to the nature of the list-generation algorithm. One class is based on a tree-search algorithm and the other is based on insight generated from the analysis of semidefinite relaxation techniques for hard demodulation. The proposed tree-search demodulators are based on a multi-stack algorithm, developed herein, for efficiently traversing the tree structure that is inherent in the MIMO demodulation problem. The proposed scheme was inspired, in part, by the stack algorithm, which stores all the visited nodes in the tree in a single stack and chooses the next node to expand based on a 'best-first' selection scheme. The proposed algorithm partitions this global stack into a stack for each level of the tree. It examines the tree in the natural ordering of the levels and performs a best-first search in each of the stacks. By assigning appropriate priorities to the level at which the search for the next leaf node re-starts, the proposed demodulators can achieve performance-complexity trade-offs that dominate several existing soft demodulators, including those based on the stack algorithm and those based on 'sphere decoding' principles, especially in the low-complexity region. In the second part of this thesis it is shown that the randomization procedure that is inherent in the semidefinite relaxation (SDR) technique for hard demodulation can be exploited to generate the list members required for list-based soft demodulation. The direct application of this observation yields list-based soft demodulators that only require the solution of one SDP per demodulation-decoding iteration. By approximating the randomization procedure by a set of independent Bernoulli trials, this requirement can be reduced to just one semidefinite program (SDP) per channel use. An advantage of these demodulators over those based on optimal tree-search algorithms is that the computational cost of solving the SDP is a low-order polynomial in the problem size. The analysis and simulation experiments provided in the thesis show that the proposed SDR-based demodulators offer an attractive trade-off between performance and computational cost. The structure of the SDP in the proposed SDR-based demodulators depends on the signaling scheme, and the initial development focuses on the case of QPSK signaling. In the last chapter of this thesis, the extension to MIMO 16-QAM systems is developed, and some interesting observations regarding some existing SDR-based hard demodulation schemes for MIMO 16-QAM systems are derived. The simulation results reveal that the excellent performance-complexity trade-off of the proposed SDR-based schemes is preserved under the extension to 16-QAM signaling. / Thesis / Doctor of Philosophy (PhD)

<p> The effectiveness of auditory frontalis EMG feedback as a means of teaching general relaxation to spastic and athetoid cerebral palsy individuals was investigated in a pilot study. It was hypothesized that an increase in voluntary ability to reduce levels of muscle activity would translate into improved functional skills and act as an effective coping response in dealing with stress and anxiety.</p> <p> Two subjects - one athetoid (female; 16 years old) and the other spastic (male; 19 years old were studied in depth, each through the use of an A-B-A single-subject design, where the B phase consisted of ten 15-minute sessions of auditory feedback of the frontalis muscle. Generalization of relaxation was assessed by monitoring forearm flexor and extensor muscle activity, peripheral skin temperature, and respiration rate. A Tektronix 4051 desktop computer was utilized to facilitate data management. In addition to the physiological measures, functional evaluations were conducted prior to and after training and a questionnaire was answered by the subject's relatives. Although there was no clear tendency for either subject to reduce absolute levels of EMG, one subject demonstrated a striking reduction in variability of muscle activity across sessions. Functional assessments for these subjects indicated mild to moderate improvements.</p> / Thesis / Master of Engineering (MEngr)

Note:

The ACL is one of the major ligaments in the knee connecting the femur to the tibia which provides stability by resisting shear in sagittal plane. ACL tears occur in 1 out of 3000, and due to inability to heal, reconstructive surgeries are performed at a rate of 200,000/year. Final graft fixation tension during surgery has been shown to wane due to stress-relaxation which has been correlated with negative clinical outcomes. Therefore, preconditioning, which currently is an isometric load (88N), is performed to remove stress-relaxation after the final tension has been applied in vivo. Three preconditioning protocols, creep, stress relaxation, and none, were tested to show significant differences and variance in graft tension after 30 minutes. The results suggest that the current preconditioning protocol may not be efficient enough to remove stress-relaxation after final fixation, and that a creep protocol causes less variability than the other preconditions performed.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.