Complexity-modulated tasks elicit differential hemodynamic activations in the primary motor cortex for upper limb motor representations. However, much is yet to be learned regarding lower limb complexity modulation, as most fNIRS complexity modulation studies focus on the upper limb. It is currently unknown whether hemodynamic activations from single-joint lower limb motor tasks are detectable by fNIRS, and further, if fNIRS can detect differences between activations from simple and complex lower limb motor tasks. An fNIRS study was conducted to investigate the effects of an unpredictable, complex force-tracking task vs. a predictable, simple force-tracking task on hemodynamic activations in the TA motor representation. No significant TA motor cortex activations were found for 4/5 participants, with one participant showing a significant activation in one channel. Lack of activation in the TA motor representation was attributed to the depth of the area within the central sulcus. Significant hemodynamic activations were also found in areas assumed to overly STG/SII, and pre-SMA/SMA. These activations were attributed to sensory integration and motor learning, respectively. An fNIRS processing review was also conducted to inform processing decisions in the first experiment and to further fNIRS usage in our lab. Common techniques were identified as low-pass, band-pass, and high-pass filters, smoothing filters, wavelet filters, and the GLM. More appropriate alternative techniques were provided, including short-separation regression, pre-whitening, and spline interpolation with a Savitsky-Golay filter. Future studies may elucidate the lack of activity in the TA motor representation, and will further basic neuroscience regarding fNIRS. / Thesis / Master of Science in Kinesiology

The main idea of this thesis is to de ne and formulate the role of bias estimation in multitarget{multisensor scenarios as a general framework for various measurement types. After a brief introduction of the work that has been done in this thesis, three main contributions are explained in detail, which exercise the novel ideas. Starting with radar measurements, a new bias estimation method that can estimate o set and scaling biases in large network of radars is proposed. Further, Cram er{Rao Lower Bound is calculated for the bias estimation algorithm to show the theoretical accuracy that can be achieved by the proposed method. In practice, communication loss is also part of the distributed systems, which sometimes can not be avoided. A novel technique is also developed to accompany the proposed bias estimation method in this thesis to compensate for communication loss at di erent rates by the use of tracklets. Next, bearing{only measurements are considered. Biases in this type of measurement can be di cult to tackle because the measurement noise and systematic biases are normally larger than in radar measurements. In addition, target observability is sensitive to sensor{target alignment and can vary over time. In a multitarget{ multisensor bearing{only scenario with biases, a new model is proposed for the biases that is decoupled form the bearing{only measurements. These decoupled bias measurements then are used in a maximum likelihood batch estimator to estimate the biases and then be used for compensation. The thesis is then expanded by applying bias estimation algorithms into video sensor measurements. Video sensor measurements are increasingly implemented in distributed systems because of their economical bene ts. However, geo{location and geo{registration of the targets must be considered in such systems. In last part of the thesis, a new approach proposed for modeling and estimation of biases in a two video sensor platform which can be used as a standalone algorithm. The proposed algorithm can estimate the gimbal elevation and azimuth biases e ectively. It is worth noting that in all parts of the thesis, simulation results of various scenarios with di erent parameter settings are presented to support the ideas, the accuracy, mathematical modelings and proposed algorithms. These results show that the bias estimation methods that have been conducted in this thesis are viable and can handle larger biases and measurement errors than previously proposed methods. Finally, the thesis conclude with suggestions for future research in three main directions. / Thesis / Doctor of Philosophy (PhD)

This study investigates methods that can be used for tracking features in computationalluid-dynamics datasets. The two approaches of overlap based feature tracking and attribute-based feature tracking are studied. Overlap based techniques use the actual degree of overlap between sucessive time steps to conclude a match. Attribute-based techniques use characteristics native to the feature being studied, like size, orientation, speed etc, to conclude a match between candidate features. Due to limitations on the number of time steps that can be held in a computer's memory, it may be possible to load only a time-subsampled data set. This might result in a decrease in the overlap obtained, and hence a subsequent decrease in the confidence of the match. This study looks into using specific attributes of features, like rotational velocity, linear velocity to predict the presence of that feature in a future time step. The use of predictive techniques is tested on swirling features, i.e., vortices. An ellipse-like representation is assumed to be a good approximation of any such feature. The location of a feature in previous time-steps are used to predict its position in a future time-step. The ellipse-like representation of the feature is translated over to the predicted location and aligned in the predicted orientation. An overlap test is then done. Use of predictive techniques will help increase the overlap, and subsequently the confidence in the match obtained. The techniques were tested on an artificial data set for linear velocity and rotation and on a real data set of simulation of flow past a cylinder. Regions of swirling flow, detected by computing the swirl parameter, were taken as features for study. The degree of overlap obtained by a basic overlap and by the use of predictive methods were tabulated. The results show that the use of predictive techniques improved the overlap.

No description available.

Target tracking refers to the process of estimating the state of a moving object from remote and noisy measurements. In this thesis we consider the Bayesian filtering framework to perform target tracking under nonlinear models, a target moving in continuous time, and measurements that are available in discrete time intervals (known as continuous-discrete). The Bayesian filtering theory establishes the mathematical basis to obtain the posterior probability density function of the state, given the measurement history. This probability density function contains all the information required about the state of the target. It is well documented that there is no exact solution for posterior density under the models mentioned. Hence, the approximation of such density functions have been studied for over four decades. The literature demonstrates that this has led to the development of multiple filters. In target tracking, due to the remote sensing performed, an additional complication emerges. The measurements received are not always from the desired target and could have originated from unknown sources, thus making the tracking more difficult. This problem is known as a measurement origin uncertainty. Additionally to the filters, different methods have been proposed to address the measurement origin uncertainty due to its negative impact, which could cause a false track. Unfortunately, a final solution has yet to be achieved. The first proposal of this thesis is a new approximate Bayesian filter for continuous-discrete systems. The new filter is a higher accuracy version of the cubature Kalman filter. This filter is developed using a fifth-degree spherical radial cubature rule and the Ito-Taylor expansion of order 1.5 for dealing with stochastic differential equations. The second proposal is an improved version of the probabilistic data association method. The proposed method utilizes the maximum likelihood values for selecting the measurements that are used for the data association. In the first experiment, the new filter is tested in a challenging 3-dimensional turn model, demonstrating superiority over other existing filters. In a second and third experiments, the proposed data association method is tested for target tracking in a 2-dimensional scenarios under heavy measurement origin uncertainty conditions. The second and third experiments demonstrate the superiority of the proposed data association method compared to the probabilistic data association. / Thesis / Doctor of Philosophy (PhD)

No description available.

Die technologische Entwicklung im Bereich der Echokardiographie hat in der letzten Dekade neue Methoden zur objektiven Erfassung der regionalen linksventrikulären Wandbewegung ermöglicht. Speckle Tracking erfasst die myokardiale Deformation durch die Positionsänderung einzelner Bildpunkte von einem Bild des analysierten Datensatzes zum nächsten. Diese Methode ist dem Gewebedoppler überlegen, insbesondere wegen ihrer Unabhängigkeit vom Anlotungswinkel. Zwei-dimensionale (2D) Speckle Tracking Analysen wurden für die klinische Praxis validiert. Die drei-dimensionale (3D) Echokardiographie erlaubt inzwischen Speckle Tracking Analysen von 3D Datensätzen, welche jedoch für die klinische Praxis noch nicht ausreichend validiert sind. Bei Patienten mit normaler regionaler linksventrikulärer Wandbewegung (N=37), sowie bei Patienten mit ischämie-bedingten Wandbewegungsstörungen (N=18) wurden 3D und 2D Speckle Tracking Analysen durchgeführt. Die Vergleichbarkeit der beiden Methoden hinschtlich der Quantifizierung von normalen und pathologischen Wandbewegungsmustern wurde anhand dieser Messungen geprüft. Des weiteren wurde der Einfluss der Bildrate und Bildqualität drei-dimensionaler Datensätze auf die Vergleichbarkeit beider Methoden analysiert. Es zeigte sich eine gute Vergleichbarkeit des 2D und 3D Speckle Tracking in der Diagnostik eingeschränkter linksventrikulärer systolischer Funktion, sowie in der Lokalisationsdiagnostik umschriebener Wandbewegungsstörungen. 2D und 3D Speckle Tracking sind jedoch noch nicht als gleichwertige Methoden anzusehen. Die Bildqualität, generell bei beiden Modalitäten - jedoch speziell bei 3D Datensätzen, sowie die Bildrate der 3D Datensätze zeigen signifikante Einflüsse auf die 3D Strain Analysen. Eine korrekte Standardisierung der analysierten Aufnahmen und eine optimale Bildqualität sind wichtige Faktoren, die die Zuverlässigkeit des 2D und 3D Speckle Trackings bestimmen.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The selection of the Intermediate Frequency (IF) bandwidth filter for a data receiver for processing PCM data is based on using a peak deviation of 0.35 times the bit rate. The optimum IF bandwidth filter is equal to the bit rate. An IF bandwidth filter of 1.5 times the bit rate degrades the data by approximately 0.7 dB. The selection of the IF bandwidth filter for tracking receivers is based on the narrowest “noise bandwidth” that will yield the best system sensitivity. In some cases the noise bandwidth of the tracking receiver is the same as the IF bandwidth of the data receiver because it is the same receiver. If this is the case, the PCM bit rate determines the IF bandwidth and establishes the system sensitivity. With increasing bit rates and increased transmitter stability characteristics, the IF bandwidth filter selection criteria for a tracking receiver must include system sensitivity considerations. The tracking receiver IF bandwidth filter selection criteria should also be based on the narrowest IF bandwidth that will not cause the tracking errors to be masked by high bit rates and alter the pedestal dynamic response. This paper describes a selection criteria for a tracking receiver IF bandwidth filter based on measurements of the tracking error signals versus antenna pedestal dynamic response. Different IF bandwidth filters for low and high bit rates were used.

Was wird zuerst verlagert und was folgt hinterher? Bei der Betrachtung der menschlichen Wahrnehmung spielen die Verlagerung des Orts der visuellen Aufmerksamkeit und die Verlagerung des Fixationsorts eine wichtige Rolle. Zur Reihenfolge, in der beide verlagert werden, existieren unterschiedliche Annahmen und Forschungsergebnisse, die vorgestellt werden. Es werden zwei zu dieser Thematik durchgeführte Experimente berichtet, in denen versucht wurde, vorliegende widersprüchliche Forschungsergebnisse zu integrieren. Es sollte gezeigt werden, dass neben der Aufmerksamkeit weitere Einflussgrößen existieren, die in Hinsicht auf diese Widersprüche Erklärungskraft besitzen. Mittels Bildbetrachtung und darauf folgender Wiedererkennensaufgaben wurde bestätigt, dass zu Beginn einer Fixation häufiger Ort und Inhalt der vorangegangenen Fixation angegeben werden. Dies wird nicht als ein Hinterherhinken der Aufmerksamkeit, sondern als Indiz für eine verzögerte Verarbeitung der Fixationsinhalte interpretiert. Im zweiten Experiment wurde zudem gezeigt, dass es kaum möglich ist, den Inhalt spezifischer vergangener Fixationen – hier konkret der vorletzten – gezielt zu erinnern.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / During shallow water exercises, the performance of acoustic tracking and telemetry systems is degraded by severe multipath interference. The feasibility of an optical source attached to the underwater vehicle (UV) and a tracking aircraft-based receiver was theoretically established. Supporting water absorption and surface interaction experiments were also performed. The limiting case was the tracking of an unmanned underwater vehicle (UUV). The requirements of daylight operation, atmospheric visibility, limited space and weight, self-contained power, exercise duration, sample rate, optimum search area, robustness in varying scattering and sea states, non-cooperating (except for low-data-rate communications of information such as depth) source and receiver, and relative simplicity, lead to two optimum candidate systems. One system uses a commercially available 5 megawatt q switched and double laser diode pumped YAG laser operating at 532 nm and 1 Hz rep rates. The second system uses a pulsed (2 μsec) zenon flash tube. Both systems satisfy the robustness constraint by intentional beam spreading. A performance constraint of 10:1 signal to noon solar upwelling shot noise ratio was imposed. This constraint can be met for water depths of 10 and 5 absorption lengths, respectively, for the laser and incoherent systems. An optimum search diameter of approximately 700 meters (m) at an optimum aircraft elevation of 3,000 meters is calculated for both systems. The 4-inch diameter F/1 wide-angle light pulse detection system gates a 4-inch diameter F/1 intensified charged coupled device (CCD) imaging system that locates the light surface penetration point. Another candidate receiver that performs both functions is a positive sensitive photomultiplier tube with crossed wire anodes. A supporting night-time experiment has been designed and is under construction.