Saudi Cultural Missions Theses & Dissertations
Permanent URI for this communityhttps://drepo.sdl.edu.sa/handle/20.500.14154/10
Browse
2 results
Search Results
Item Restricted Spinal kinematic variability in people with chronic low back pain(University of Birmingham, 2024-05-29) Alsubaie, Amal Mutlag M; Falla, DeborahLow back pain (LBP) is one of the leading causes of disability globally and chronic non-specific LBP (CNSLBP) accounts for the vast majority of cases. It is widely acknowledged that people with LBP move differently than pain-free individuals. An abundance of research has examined trunk motor control to understand how movement is controlled in the presence of LBP by evaluating both trunk movement patterns and trunk muscle activity. A commonly observed motor adaptation to spinal pain is a change in spine kinematics, such as angular displacement, angular velocity, as well as changes in the variability of these kinematic variables. However, kinematic variability as a motor adaptation to pain in people with CNSLBP has received less attention and still requires further clarification. This thesis presents research to investigate trunk motor adaptations in people with CNSLBP, specifically, by evaluating kinematic variability differences compared to asymptomatic individuals as a critical element of motor performance during repetitive movements. Additionally, the thesis explores factors such as their trunk muscle co-activation patterns and their clinical characteristics in order to gain insights into possible explanations for different movement variability. The first study was a systematic review which confirmed the existence of a different motor pattern in people with CNSLBP, as indicated by differences in spinal kinematic variability compared to asymptomatic individuals during various functional and non-functional repetitive trunk movements. Furthermore, two experimental studies explored the differences in kinematic variability in people with CNSLBP compared to asymptomatic individuals performing two different tasks using the same linear metric to measure variability during repetitive trunk movements. In the second study we applied a novel real-time tracking task using a 3D motion capture system to assess trunk motor control. This study did not reveal any differences in movement variability in CNSLBP people when compared with asymptomatic individuals, however, it showed that movement variability over repeated tracking cycles was associated with the degree of fear of movement in ii people with CNSLBP. Additionally, the response of those with CNSLBP was consistently delayed in tracking the visual feedback compared to the asymptomatic individuals. The third study tested a lifting task reflecting activities of daily living which detected an increase in movement variability in individuals with CNSLBP, despite performing the task within the same spinal range of motion. Moreover, two additional experiments have introduced the novel application of helical axis (HA) parameters as a measure of spinal kinematic variability during repetitive trunk movements. The fourth study tested the use of HA parameters on asymptomatic individuals which revealed its sensitivity to changes in movement plane and movement speed. The first application of this measure on people with CNSLBP was in the fifth study which revealed an increase in spinal kinematic variability compared to asymptomatic individuals during active trunk repetitive movements, irrespective of the speed or direction of movement. In addition, people with a higher fear of movement showed the lowest kinematic variability. Overall, this thesis further highlights the interaction between physical and psychological features of CNSLBP. The thesis offers new insights into how motor adaptations to spinal pain are present, which suggests the need for tailored interventions to address the unique mechanical presentation of each individual with CNSLBP.23 0Item Restricted High-Precision GNSS Kinematic Relative Positioning: Methods and Assessment(Saudi Digital Library, 2023-12-17) Alanazi, Abdullah; Wang, LeiIn today's dynamic positioning applications, achieving sub-meter or centimeter-level precision has become increasingly crucial in various kinematic positioning applications. This holds particularly true for navigating rovers within challenging environments where GNSS measurements' quality limitations hinder accurate positioning. To enhance positioning accuracy, GNSS carrier phase measurements have gained significant importance. These measurements provide tracking precision approximately a hundred times finer than pseudorange measurements. However, these measurements present a challenge known as 'integer ambiguity,' which prevents their direct application in positioning. While a portion of the carrier phase measurement can be accurately measured, the remaining portion, representing a full cycle, remains unknown. Resolving this unknown cycle number is known as the 'ambiguity estimation problem' within the context of GNSS positioning. Achieving centimeter-level positioning accuracy is only possible if we successfully resolve this integer cycle number. This dissertation focuses on applying carrier phase measurements in demanding scenarios, particularly in vehicle positioning. Our primary goal is to develop an efficient algorithm and software for achieving centimeter-level accuracy in kinematic positioning using carrier phase measurements in these challenging contexts. We realize this goal through GNSS differential techniques that mitigate errors in GNSS-derived positions by leveraging correlated errors in GNSS measurements, augmented with data from a reference GNSS receiver. The dissertation explores various ambiguity resolution methods, including Full Ambiguity Resolution (FAR), Partial Ambiguity Resolution (PAR), and Ionosphere-free (Iono-free), aimed at improving position determination accuracy and enabling the reliable use of carrier phase measurements. We implement MATLAB software to enhance GNSS positioning accuracy, utilizing an extended Kalman filtering technique to better model the kinematics of a moving receiver. Our assessment is based on real-world data collected from Ohio State University's west campus area and CORS stations, spanning diverse baseline lengths and receiver types, from geodetic to low-cost receivers. Our software extends to multi-baseline scenarios, surpassing single baselines. Notably, the PAR method significantly enhances solution fix rates compared to the FAR and Iono-free methods, especially in short baseline scenarios, resulting in improved positioning accuracy. The comprehensive testing and validation conducted underscore the substantial contribution of our software to achieving centimeter-level kinematic positioning accuracy. Moreover, the analysis demonstrates that with the increase in baseline lengths, FAR and PAR methods exhibit a decline in fix rates and an increase in standard deviation values. This highlights the challenge of maintaining precise and fixed solutions over longer baselines. The PAR method outperformed the FAR method, especially in terms of fix rates, particularly for longer baselines. On the other hand, the Iono-free method faced significant challenges in high-dynamic scenarios with longer baselines, resulting in decreased precision and reliability. For CORS station data only in the case of medium to long baseline lengths, the Iono-free method exhibited superior performance compared to the FAR and PAR methods. However, the PAR method delivered results on par with those obtained from the Iono-free method. In contrast, the FAR method faced challenges in maintaining the same level of performance as the PAR and Iono-free methods for these longer baseline scenarios.37 0