+publisher:"University of Texas – Austin" +contributor:("Barr, Ronald E")

University of Texas – Austin

1. -4766-7868. Self-learning control of automated drilling operations.

Degree: PhD, Mechanical Engineering, 2018, University of Texas – Austin

► In recent years, drilling automation has sparked significant interest in both the upstream oil and gas industry and the drilling research community. Automation of various… (more)

▼ In recent years, drilling automation has sparked significant interest in both the upstream oil and gas industry and the drilling research community. Automation of various drilling tasks can potentially allow for higher operational efficiency, increased consistency, and reduced risk of trouble events. However, wide adoption of drilling automation has been slow. This can be primarily attributed to the complex nature of drilling, and the high variability in well types and rig specifications that prevent the deployment of off-the-shelf automation solutions. Such complexities justify the need for an automation system that can self-learn by interacting with the drilling environment to reduce uncertainty. The aim of this dissertation is to determine how a drilling automation system can learn from the environment and utilize this learning to control drilling tasks optimally. To provide an answer, the importance of learning, as well as its limitations in dealing with challenges such as insufficient training data, are explored. A self-learning control system is presented that addresses the aforementioned research question in the context of optimization, control, and event detection. By adopting an action-driven learning approach, the control system can learn the parameters that describe system dynamics. An action-driven approach is shown to also enable the learning of the relationship between control actions and user-defined performance metrics. The resulting knowledge of this learning process enables the system to make and execute optimal decisions without relying on simplifying assumptions that are often made in the drilling literature. Detection of trouble drilling events is explored, and methods for reduction of false/missed alarms are presented to minimize false interruptions of the drilling control system. The subcomponents of the self-learning control system are validated using simulated and actual field data from drilling operations to ascertain the effectiveness of the proposed methods. Advisors/Committee Members: Oort, Eric van (advisor), Fernandez, Benito R. (advisor), Chen, Dongmei (committee member), Barr, Ronald E. (committee member), Niekum, Scott (committee member).

Subjects/Keywords: Automated drilling; Drilling optimization; Self-learning control

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APA (6^th Edition):

-4766-7868. (2018). Self-learning control of automated drilling operations. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/65829

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Chicago Manual of Style (16^th Edition):

-4766-7868. “Self-learning control of automated drilling operations.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/65829.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-4766-7868. “Self-learning control of automated drilling operations.” 2018. Web. 05 Mar 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-4766-7868. Self-learning control of automated drilling operations. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/65829.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-4766-7868. Self-learning control of automated drilling operations. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/65829

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

2. Kim, Jaeweon. Bandwidth and power efficient wireless spectrum sensing networks.

Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-2727

► Opportunistic spectrum reuse is a promising solution to the two main causes of spectrum scarcity: most of the radio frequency (RF) bands are allocated by… (more)

▼ Opportunistic spectrum reuse is a promising solution to the two main causes of spectrum scarcity: most of the radio frequency (RF) bands are allocated by static licensing, and many of them are underutilized. Frequency spectrum can be more efficiently utilized by allowing communication systems to find out unoccupied spectrum and to use it harmlessly to the licensed users. Reliable sensing of these spectral opportunities is perhaps the most essential element of this technology. Despite significant work on spectrum sensing, further performance improvement is needed to approach its full potential. In this dissertation, wireless spectrum sensing networks (WSSNs) are investigated for reliable detection of the primary (licensed) users, that enables efficient spectrum utilization and minimal power consumption in communications. Reliable spectrum sensing is studied in depth in two parts: a single sensor algorithm and then cooperative sensing are proposed based on a spectral covariance sensing (SCS). The first novel contribution uses different statistical correlations of the received signal and noise in the frequency domain. This detector is analyzed theoretically and verified through realistic simulations using actual digital television signals captured in the US. The proposed SCS detector achieves significant improvement over the existing solutions in terms of sensitivity and also robustness to noise uncertainty. Second, SCS is extended to a distributed WSSN architecture to allow cooperation between 2 or more sensors. Theoretical limits of cooperative white space sensing under correlated shadowing are investigated. We analyze the probability of a false alarm when each node in the WSSN detects the white space using the SCS detection and the base station combines individual results to make the final decision. The detection performance compared with that of the cooperative energy detector is improved and fewer sensor nodes are needed to achieve the same sensitivity. Third, we propose a low power source coding and modulation scheme for power efficient communication between the sensor nodes in WSSN. Complete analysis shows that the proposed scheme not only minimizes total power consumption in the network but also improves bit error rate (BER). Advisors/Committee Members: Andrews, Jeffrey G. (advisor), Vishwanath, Sriram (committee member), Arapostathis, Aristotle (committee member), Vikalo, Haris (committee member), Barr, Ronald E. (committee member).

Subjects/Keywords: Spectrum sensing; Cognitive radio; Spectral covariance; Minimum energy; CDMA; Wireless networks

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APA (6^th Edition):

Kim, J. (2011). Bandwidth and power efficient wireless spectrum sensing networks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-2727

Chicago Manual of Style (16^th Edition):

Kim, Jaeweon. “Bandwidth and power efficient wireless spectrum sensing networks.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-2727.

MLA Handbook (7^th Edition):

Kim, Jaeweon. “Bandwidth and power efficient wireless spectrum sensing networks.” 2011. Web. 05 Mar 2021.

Vancouver:

Kim J. Bandwidth and power efficient wireless spectrum sensing networks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2727.

Council of Science Editors:

Kim J. Bandwidth and power efficient wireless spectrum sensing networks. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2727

University of Texas – Austin

3. Shell, Courtney Elyse. Tuning prosthetic foot stiffness to improve lower-limb amputee mobility.

Degree: PhD, Mechanical Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/68400

► The foot, ankle and surrounding musculature play key roles in walking and maneuvering. They provide not only body support but also forward propulsion, terrain adaptation,… (more)

▼ The foot, ankle and surrounding musculature play key roles in walking and maneuvering. They provide not only body support but also forward propulsion, terrain adaptation, and contributions to mediolateral balance control. Prosthetic feet have previously been designed to provide body support and, to some degree, forward propulsion and sagittal-plane terrain adaptation. However, there has been little exploration of how prosthesis design affects performance in tasks that challenge mediolateral balance, such as turning and walking on cross-slopes. In Chapter 2, the effects of prosthetic foot stiffness on unilateral transtibial amputee gait during turning were explored. Changes found in sagittal-plane kinematics and kinetics caused by more compliant prostheses were similar to those seen previously in studies of straight-line walking. This included decreased body support, increased residual limb propulsion and greater limb flexion. Mediolateral balance, measured by peak-to-peak range of whole-body angular momentum, improved with decreasing stiffness, but adaptations in coronal-plane angles, work and ground reaction force impulses were less systematic. In Chapter 3, forward dynamics simulations of a unilateral transtibial amputee stepping on a cross-slope were used to identify optimal coronal-plane stiffness profiles that improved balance control by decreasing changes in coronal-plane whole-body angular momentum. Profiles that decreased these changes were identified for ankle-inverting and ankle-everting cross-slopes as well as level ground. The change in coronal-plane whole-body angular momentum decreased with an increase in stiffness for ankle-everting cross-slopes but with a decrease in stiffness for ankle-inverting cross-slopes and level ground. Stiffness profiles influenced mediolateral balance control through the medial GRF, but were specific to each surface type. These results highlight the need to identify the surface type encountered (level, ankle-inverting or ankle-everting cross-slope) so that the stiffness profile appropriate for the surface can be set. To that end, in Chapter 4, measurements from the residual limb useful for predicting a cross-slope with a pattern recognition algorithm were identified. Residual limb kinematics, especially measurements from the foot, shank and ankle, were found to successfully predict the surface type with high accuracy. These studies have provided rationale and foundation for designing prostheses that help maintain mediolateral balance control when encountering turning or uneven terrain. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E (committee member), Fey, Nicholas P (committee member), Klute, Glenn K (committee member), Sulzer, James S (committee member).

Subjects/Keywords: Transtibial amputee; Turning; Cross-slope; Gait; Dynamic balance; Forward dynamics simulation; Pattern recognition; Terrain prediction; Kinematics

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APA (6^th Edition):

Shell, C. E. (2016). Tuning prosthetic foot stiffness to improve lower-limb amputee mobility. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68400

Chicago Manual of Style (16^th Edition):

Shell, Courtney Elyse. “Tuning prosthetic foot stiffness to improve lower-limb amputee mobility.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/68400.

MLA Handbook (7^th Edition):

Shell, Courtney Elyse. “Tuning prosthetic foot stiffness to improve lower-limb amputee mobility.” 2016. Web. 05 Mar 2021.

Vancouver:

Shell CE. Tuning prosthetic foot stiffness to improve lower-limb amputee mobility. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/68400.

Council of Science Editors:

Shell CE. Tuning prosthetic foot stiffness to improve lower-limb amputee mobility. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/68400

University of Texas – Austin

4. Ock, JinGyu. Development of a laser foaming process for high throughput three-dimensional tissue model devices.

Degree: PhD, Mechanical Engineering, 2017, University of Texas – Austin

URL: http://hdl.handle.net/2152/63053

► A three-dimensional (3D) porous structure on biodegradable or biocompatible polymers have attracted tremendous attention in numerous bio-related areas including 3D cell culturing and tissue engineering… (more)

▼ A three-dimensional (3D) porous structure on biodegradable or biocompatible polymers have attracted tremendous attention in numerous bio-related areas including 3D cell culturing and tissue engineering because of their microenvironment similar to ones in vivo. In this study, a novel fabrication process, named selective laser foaming, was developed to create localized 3D porous structure on a polymer chip. The effects of laser power and lasing time on the porous structure were studied both experimentally and through finite element modeling. A high throughput two-chamber tissue model platform was developed using the proposed selective laser foaming process. For comparison, cell culture studies were conducted with both selective laser foamed and unfoamed polylactic acid (PLA) samples using T98G cells. The results show that by laser foaming gas-impregnated polylactic acid it is possible to generate an array of inverse cone-shaped wells with porous walls. The size of the foamed region can be controlled with laser power and exposure time, while the pore size of the scaffold can be manipulated with the saturation pressure. The finite element modeling results showed good agreement with the experimental data; therefore, the model could be used to optimize and control the selective foaming process. T98G cells grew well in the foamed scaffolds, forming clusters that have not been observed in 2D cell cultures. Cells were more viable in the 3D scaffolds than in the 2D cell culture cases, suggesting that the 3D porous microarray could be used for parallel studies of drug toxicity, guided stem cell differentiation, and DNA binding profiles. As an example, a high-throughput two-chamber 3D tissue model platform driven by the centrifugal force was developed for drug screening. The selective laser foaming process was calibrated to fabricate 3D scaffold on a commercially available compact disc (CD) made of polycarbonate (PC). Laser foaming of gas saturated polycarbonate created inverse cone-shaped wells with micro-sized porous structure underneath the surface. The open pores were hundreds of micrometers in diameter and depth. The pore size of the underneath porous structure was several tens of micrometers. The size of the well was dependent on the laser power and laser exposure time. Two laser-foamed scaffolds were fabricated in tandem and two mechanically-machined chambers were placed adjacent to the scaffolds, respectively. All scaffolds and chambers were in line and all of them were connected with micro-channels. The surface was coated with polydopamine (PDA) in order to increase the hydrophilicity and biocompatibility. After sterilization, human glioblastoma multiforme (M059K) and hepatoblastoma (C3A sub28) were seeded in the two 3D scaffolds separately and cultured for up to four weeks. These cells grew well in the scaffolds and cell aggregates were observed, suggesting that the developed two-chamber tissue model array could be useful for high-throughput biochemical assays. Advisors/Committee Members: Li, Wei, doctor of mechanical engineering (advisor), Barr, Ronald E. (committee member), Ben-Yakar, Adela (committee member), Seepersad, Carolyn C (committee member), Suggs, Laura J (committee member).

Subjects/Keywords: Tissue microarray; Laser foaming; Solid-state foaming; Three-dimensional cell culture; Biodegradable polymer; Microliter tissue engineering scaffolds; Finite element modeling (FEM); Polycarbonate; Polydopamine coating; Lab on disc; Centrifugal microfluidics

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APA (6^th Edition):

Ock, J. (2017). Development of a laser foaming process for high throughput three-dimensional tissue model devices. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/63053

Chicago Manual of Style (16^th Edition):

Ock, JinGyu. “Development of a laser foaming process for high throughput three-dimensional tissue model devices.” 2017. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/63053.

MLA Handbook (7^th Edition):

Ock, JinGyu. “Development of a laser foaming process for high throughput three-dimensional tissue model devices.” 2017. Web. 05 Mar 2021.

Vancouver:

Ock J. Development of a laser foaming process for high throughput three-dimensional tissue model devices. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2017. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/63053.

Council of Science Editors:

Ock J. Development of a laser foaming process for high throughput three-dimensional tissue model devices. [Doctoral Dissertation]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/63053

University of Texas – Austin

5. Ranz, Ellyn Cymbre. Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies.

Degree: PhD, Mechanical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/39695

► Traumatic injuries to the extremities are commonly observed in emergency room patients and military personnel in combat. Restoring high mobility and functionality is a primary… (more)

▼ Traumatic injuries to the extremities are commonly observed in emergency room patients and military personnel in combat. Restoring high mobility and functionality is a primary goal post-injury, which may require the use of rehabilitative devices, surgical interventions, and rehabilitation therapies. The research detailed in this dissertation investigates specific elements of these approaches through the use of experimental study and modeling and simulation. In the first study, the influence of passive-dynamic ankle-foot orthosis bending axis on the gait performance of limb salvage subjects was investigated. Bending axis location was altered by fabricating customized orthosis components using additive manufacturing and was tested in a gait laboratory. Altering bending axis location did not result in large or consistent changes in gait measures, however subjects expressed strong preferences for bending axis condition and preference was strongly related to specific gait measures. This suggests that preference and comfort are important factors guiding the prescription of bending axis location. In the second study, musculoskeletal modeling was used to examine the influence of transfemoral amputation surgical techniques on muscle capacity to generate forces and moments about the hip. Muscle reattachment tension and stabilization were shown to be critical parameters for post-amputation capacity, which supports the use of myodesis stabilization (muscle is reattached directly to bone) in amputation procedures. In the third study, a forward dynamics simulation of transfemoral amputee gait was developed and used to examine individual muscle and prosthesis contributions to walking subtasks. The residual hip muscles, and intact ankle, knee, and hip muscles worked synergistically to provide body support, anteroposterior propulsion, mediolateral control, and leg swing. Increased contributions of contralateral muscles to ipsilateral subtasks as well as increased duration of specific muscle contributions were observed in comparison to non-amputee and transtibial amputee walking. These findings can be used to help develop targeted rehabilitation therapies and improve transfemoral amputee locomotion. Through elucidating the influence of PD-AFO bending axis on gait performance as well as the influence of transfemoral amputation surgical techniques on muscle capacity and function, this research provides a foundation for improved rehabilitation outcomes, and thus mobility for individuals who have experienced traumatic lower-limb injuries. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E (committee member), Crawford, Richard H (committee member), Sulzer, James S (committee member), Wilken, Jason M (committee member).

Subjects/Keywords: Biomechanics; Limb salvage; Transfemoral amputee; Additive manufacturing; Musculoskeletal modeling; Forward dynamics simulation

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APA (6^th Edition):

Ranz, E. C. (2016). Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/39695

Chicago Manual of Style (16^th Edition):

Ranz, Ellyn Cymbre. “Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/39695.

MLA Handbook (7^th Edition):

Ranz, Ellyn Cymbre. “Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies.” 2016. Web. 05 Mar 2021.

Vancouver:

Ranz EC. Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/39695.

Council of Science Editors:

Ranz EC. Mobility in individuals with traumatic lower-limb injuries : implications for device design, surgical intervention and rehabilitation therapies. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/39695

University of Texas – Austin

6. Harper, Nicole Guckert. Muscle function and coordination of amputee and non-amputee stair ascent.

Degree: PhD, Mechanical engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31547

► Stair ascent is a common activity of daily living and is necessary for maintaining independence in a variety of community environments. However, it can be… (more)

▼ Stair ascent is a common activity of daily living and is necessary for maintaining independence in a variety of community environments. However, it can be a biomechanically challenging task. For example, for transtibial amputees the loss of the ankle plantarflexors coupled with the task demands of stair ascent require amputees to develop compensatory mechanisms that utilize the prosthesis and remaining musculature. The overall goal of this research was to use advanced musculoskeletal modeling and simulation techniques in a series of studies to understand how individual muscles contribute to stair ascent in non-amputees and how unilateral transtibial amputees compensate with the prosthesis and remaining musculature during stair ascent. In the first study, a simulation of non-amputee stair ascent was developed to elucidate the contributions of individual muscles and the biomechanical mechanisms by which they accomplish stair ascent. The hip abductors, hip extensors, knee extensors and plantarflexors were found to work synergistically to generate, absorb and/or transfer mechanical power to accomplish stair ascent. In the second study, a simulation of transtibial amputee stair ascent was generated to identify functional deficits and compensations necessary for amputees to ascend stairs. The passive prosthesis was able to emulate the role of the uniarticular plantarflexors, but was unable to replicate the role of the biarticular plantarflexors. As a result, compensations from other muscles were necessary. In the final study, simulations of non-amputee and amputee stair ascent were used to determine the contributions of individual muscles and the prosthesis to dynamic balance control, which was quantified using whole-body angular momentum. The prosthesis was able to replicate the role of the plantarflexors in the regulation of sagittal-plane and, to a lesser extent, transverse-plane angular momentum. However, while the non-amputee plantarflexors contributed minimally to frontal-plane angular momentum, the prosthesis acted to rotate the body towards the contralateral leg, which required additional muscle compensations. By understanding the role of the individual muscles and prosthesis in achieving stair ascent and identifying the compensations used by amputees, this research provides a foundation for designing refined prostheses and targeted rehabilitation programs that improve an individual’s ability to ascend stairs. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E (committee member), Deshpande, Ashish D (committee member), Sulzer, James S (committee member), Wilken, Jason M (committee member).

Subjects/Keywords: Stair ascent; Amputee; Forward dynamics; Modeling and simulation; Muscle contributions; Whole-body angular momentum

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APA (6^th Edition):

Harper, N. G. (2015). Muscle function and coordination of amputee and non-amputee stair ascent. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31547

Chicago Manual of Style (16^th Edition):

Harper, Nicole Guckert. “Muscle function and coordination of amputee and non-amputee stair ascent.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/31547.

MLA Handbook (7^th Edition):

Harper, Nicole Guckert. “Muscle function and coordination of amputee and non-amputee stair ascent.” 2015. Web. 05 Mar 2021.

Vancouver:

Harper NG. Muscle function and coordination of amputee and non-amputee stair ascent. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/31547.

Council of Science Editors:

Harper NG. Muscle function and coordination of amputee and non-amputee stair ascent. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31547

University of Texas – Austin

7. -8135-3980. Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair.

Degree: PhD, Mechanical Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/1371

► The mitral valve (MV) is the left atrio-ventricular heart valve that regulates blood flow direction during the cardiac cycle. Among the four heart valves, MV… (more)

Subjects/Keywords: Mitral valve; Ischemic mitral regurgitation; Mitral valve repair surgery; Computational modeling; Finite element analysis; Large deformation continuum mechanics; Structural constitutive relations; Fourier analysis; Nonlinear programming

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APA (6^th Edition):

-8135-3980. (2019). Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/1371

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-8135-3980. “Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://dx.doi.org/10.26153/tsw/1371.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-8135-3980. “Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair.” 2019. Web. 05 Mar 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-8135-3980. Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Mar 05]. Available from: http://dx.doi.org/10.26153/tsw/1371.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-8135-3980. Multi-resolution modeling of the mitral valve : a novel computational pipeline for patient-specific simulations of valve repair. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/1371

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

8. Fey, Nicholas Phillip. The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics.

Degree: PhD, Mechanical Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4686

► Unilateral below-knee amputees commonly experience asymmetrical gait patterns and develop comorbidities in their intact (non-amputated) and residual (amputated) legs, with the mechanisms leading to these… (more)

▼ Unilateral below-knee amputees commonly experience asymmetrical gait patterns and develop comorbidities in their intact (non-amputated) and residual (amputated) legs, with the mechanisms leading to these asymmetries and comorbidities being poorly understood. Prosthetic feet have been designed in an attempt to minimize walking asymmetries by utilizing elastic energy storage and return (ESAR) to help provide body support, forward propulsion and leg swing initiation. However, identifying the influence of walking speed and prosthetic foot stiffness on amputee gait mechanics is needed to develop evidence-based rationale for prosthetic foot selection and treatment of comorbidities. In this research, experimental and modeling studies were performed to identify the influence of walking speed and prosthetic foot stiffness on amputee walking mechanics. The results showed that when asymptomatic and relatively new amputees walk using clinically prescribed prosthetic feet across a wide range of speeds, loading asymmetries exist between the intact and residual knees. However, knee intersegmental joint force and moment quantities in both legs were not higher compared to non-amputees, suggesting that increased knee loads leading to joint disorders may develop in response to prolonged prosthesis usage or the onset of joint pathology over time. In addition, the results showed that decreasing ESAR foot stiffness can increase prosthesis range of motion, mid-stance energy storage, and late-stance energy return. However, the prosthetic foot contributions to forward propulsion and swing initiation were limited due to muscle compensations needed to provide body support and forward propulsion in the absence of residual leg ankle muscles. A study was also performed that integrated design optimization with forward dynamics simulations of amputee walking to identify the optimal prosthetic foot stiffness that minimized metabolic cost and intact knee joint forces. The optimal stiffness profile stiffened the toe and mid-foot while making the ankle less stiff, which decreased the intact knee joint force during mid-stance while reducing the overall metabolic cost of walking. These studies have provided new insight into the relationships between prosthetic foot stiffness and amputee walking mechanics, which provides biomechanics-based rationale for prosthetic foot prescription that can lead to improved amputee mobility and overall quality of life. Advisors/Committee Members: Neptune, Richard R. (advisor), Abraham, Lawrence D. (committee member), Barr, Ronald E. (committee member), Crawford, Richard H. (committee member), Longoria, Raul G. (committee member).

Subjects/Keywords: Biomechanics; Transtibial amputee; Energy storage and return; Prosthetic foot stiffness

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APA (6^th Edition):

Fey, N. P. (2011). The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4686

Chicago Manual of Style (16^th Edition):

Fey, Nicholas Phillip. “The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4686.

MLA Handbook (7^th Edition):

Fey, Nicholas Phillip. “The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics.” 2011. Web. 05 Mar 2021.

Vancouver:

Fey NP. The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4686.

Council of Science Editors:

Fey NP. The influence of prosthetic foot design and walking speed on below-knee amputee gait mechanics. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4686

9. Jin, Hiroshi. A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement.

Degree: PhD, Mechanical Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-08-6123

► A computational neural and biomechanical system for human bicycle pedaling is developed in order to study the interaction between the central nervous system and the… (more)

Subjects/Keywords: Motor control; Neuroscience; Computer simulation; Biomechanics

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APA (6^th Edition):

Jin, H. (2012). A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-08-6123

Chicago Manual of Style (16^th Edition):

Jin, Hiroshi. “A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2012-08-6123.

MLA Handbook (7^th Edition):

Jin, Hiroshi. “A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement.” 2012. Web. 05 Mar 2021.

Vancouver:

Jin H. A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6123.

Council of Science Editors:

Jin H. A theoretical neuro-biomechanical model of proprioceptive control for lower extremity movement. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6123

10. Singhal, Vivek, Ph. D. Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines.

Degree: PhD, Mechanical Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/2912

► There is a need for advanced technology that can accurately measure the density and mass flow rate of drilling fluids at the high pressure well… (more)

▼ There is a need for advanced technology that can accurately measure the density and mass flow rate of drilling fluids at the high pressure well inlet in real-time. Current reliance on antiquated metering technologies such as the pressurized mud balance and the pump stroke counter to make these measurements greatly impedes our ability to accurately predict the near well bore pressure profile and measure the delta flow rate, which is one of the primary indicators for trouble events such as kicks or lost circulation. In order to address this gap in technology an X-ray sensor was developed to make real-time measurements at greater than 99% percent accuracy and 1 Hz measurement frequency. The X-ray sensor can measure the density of drilling fluids in the 8 ppg to 20 ppg range and with flow rates of up to 1200 gpm. These measurements are made using 320 kV/1500W polychromatic X-ray source, which is well within the range of readily available industrial X-ray tubes. In the past such measurements would require X-ray voltages that could only be achieved with linear accelerators thereby making the cost and size of equipment non-conducive to the drilling environment. However, recent advances in pipe manufacturing, particularly using a class of low density and high pressure materials known as carbon fiber reinforced polymers (CRPs) and, are now making it viable to re-visit relatively low cost X-rays systems for density and mass flowrate measurements. Windows constructed from CRPs allow us to bypass the high density carbon steel standpipe and make measurements at voltages that do not require a linear accelerator. In this paper we discuss the design and implementation of a CRP based X-ray sensor that is used to measure drilling mud density and mass flowrate at the high pressure well inlet. Advisors/Committee Members: Oort, Eric van (advisor), Chen, Dongmei (committee member), Bovik, Alan C (committee member), Barr, Ronald E (committee member), DiCarlo, David (committee member).

Subjects/Keywords: Density; Flow rate; High pressure; X-ray; Drilling; Automation; Sensor; Measurement

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APA (6^th Edition):

Singhal, Vivek, P. D. (2019). Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/2912

Chicago Manual of Style (16^th Edition):

Singhal, Vivek, Ph D. “Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://dx.doi.org/10.26153/tsw/2912.

MLA Handbook (7^th Edition):

Singhal, Vivek, Ph D. “Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines.” 2019. Web. 05 Mar 2021.

Vancouver:

Singhal, Vivek PD. Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Mar 05]. Available from: http://dx.doi.org/10.26153/tsw/2912.

Council of Science Editors:

Singhal, Vivek PD. Design and development of an X-ray sensor to measure the density and flow rate of drilling fluids in high pressure lines. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/2912

11. Hall, Allison Leigh. Understanding changes in post-stroke walking ability through simulation and experimental analyses.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-12-2363

► Post-stroke hemiparesis usually leads to slow and asymmetric gait. Improving walking ability, specifically walking speed, is a common goal post-stroke. To develop effective post-stroke rehabilitation… (more)

▼ Post-stroke hemiparesis usually leads to slow and asymmetric gait. Improving walking ability, specifically walking speed, is a common goal post-stroke. To develop effective post-stroke rehabilitation interventions, the underlying mechanisms that lead to changes in walking ability need to be fully understood. The overall goal of this research was to investigate the deficits that limit hemiparetic walking ability and understand the influence of post-stroke rehabilitation on walking ability in persons with post-stroke hemiparesis. Forward dynamics walking simulations of hemiparetic subjects (and speed-matched controls) with different levels of functional walking status were developed to investigate the relationships between individual muscle contributions to pre-swing forward propulsion, swing initiation and power generation subtasks and functional walking status. The analyses showed that muscle contributions to the walking subtasks are indeed related to functional walking status in the hemiparetic subjects. Increased contributions from the paretic leg muscles (i.e., plantarflexors and hip flexors) and reduced contributions from the non-paretic leg muscles (i.e., knee and hip extensors) to the walking subtasks were critical in obtaining higher functional walking status. Changes in individual muscle contributions to propulsion during rehabilitation were investigated by developing a large number of subject-specific forward dynamics simulations of hemiparetic subjects (with different levels of pre-training propulsion symmetry) walking pre- and post-locomotor training. Subjects with low paretic leg propulsion pre-training increased contributions to propulsion from both paretic leg (i.e., gastrocnemius) and non-paretic leg muscles (i.e., hamstrings) to improve walking speed during rehabilitation. Subjects with high paretic leg propulsion pre-training improved walking speed by increasing contributions to propulsion from the paretic leg ankle plantarflexors (i.e., soleus and gastrocnemius). This study revealed two primary strategies that hemiparetic subjects use to increase walking speed during rehabilitation. Experimental analyses were used to determine post-training biomechanical predictors of successful post-stroke rehabilitation, defined as performance over a 6-month follow-up period following rehabilitation. The strongest predictor of success was step length symmetry. Other potential predictors of success were identified including increased paretic leg hip flexor output in late paretic leg single-limb stance, increased paretic leg knee extensor output from mid to late paretic leg stance and increased paretic leg propulsion during pre-swing. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E. (committee member), Crawford, Richard H. (committee member), Dingwell, Jonathan B. (committee member), Kautz, Steven A. (committee member).

Subjects/Keywords: Biomechanics; Hemiparesis; Gait; Post-stroke hemiparesis; Post-stroke walking; Post-stroke rehabilitation; Walking biomechanics

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APA (6^th Edition):

Hall, A. L. (2010). Understanding changes in post-stroke walking ability through simulation and experimental analyses. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-12-2363

Chicago Manual of Style (16^th Edition):

Hall, Allison Leigh. “Understanding changes in post-stroke walking ability through simulation and experimental analyses.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2010-12-2363.

MLA Handbook (7^th Edition):

Hall, Allison Leigh. “Understanding changes in post-stroke walking ability through simulation and experimental analyses.” 2010. Web. 05 Mar 2021.

Vancouver:

Hall AL. Understanding changes in post-stroke walking ability through simulation and experimental analyses. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2363.

Council of Science Editors:

Hall AL. Understanding changes in post-stroke walking ability through simulation and experimental analyses. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-12-2363

12. Slowik, Jonathan Steven. The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand.

Degree: PhD, Mechanical engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31544

► There are millions of individuals throughout the world that rely on manual wheelchair propulsion as their primary method of mobility. Due to the considerable physical… (more)

▼ There are millions of individuals throughout the world that rely on manual wheelchair propulsion as their primary method of mobility. Due to the considerable physical demand of wheelchair propulsion, these individuals are at an increased risk of developing upper extremity pain and injuries that can lead to a progressive decline in independence and quality of life. The overall goal of this research was to use a combination of experimental analyses and forward dynamics simulation techniques to gain an increased understanding of the relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand. In the first study, a set of simulations was used to investigate the compensatory mechanisms that result from weakness in specific muscle groups. The simulation results suggested that the upper extremity musculature is robust to weakness in individual muscle groups as other muscles were able to compensate and restore normal propulsion mechanics. However, high stress levels and potentially harmful shifts in power generated by the rotator cuff muscles were observed. Such overuse could lead to the development of pain and injury in these muscles, suggesting that rehabilitation programs should target strengthening these muscles. In the second study, a set of objective quantitative parameters was developed to characterize kinematic hand patterns and assess the influence of propulsion speed and grade of incline on the patterns preferred by a group of 170 experienced manual wheelchair users. Increased propulsion speed resulted in a shift away from under-rim hand patterns while increased grade resulted in the hand remaining near the handrim throughout the propulsion cycle. These results identified how individuals modify their hand patterns in response to different propulsion conditions encountered in daily activities. In the third study, simulations of four commonly observed hand pattern types were generated. The simulations revealed the double loop and semi-circular patterns had the lowest overall muscle stress and total muscle power, suggesting that these hand patterns may reduce upper extremity demand. Together, the results of these studies have provided a scientific basis for designing rehabilitation and training programs aimed at reducing the prevalence of upper extremity injury and pain among individuals who use manual wheelchairs. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E (committee member), Deshpande, Ashish D (committee member), Mulroy, Sara J (committee member), Requejo, Philip S (committee member).

Subjects/Keywords: Manual wheelchair propulsion; Propulsion pattern; Hand pattern

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APA (6^th Edition):

Slowik, J. S. (2015). The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31544

Chicago Manual of Style (16^th Edition):

Slowik, Jonathan Steven. “The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/31544.

MLA Handbook (7^th Edition):

Slowik, Jonathan Steven. “The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand.” 2015. Web. 05 Mar 2021.

Vancouver:

Slowik JS. The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/31544.

Council of Science Editors:

Slowik JS. The relationships between muscle weakness, wheelchair propulsion technique and upper extremity demand. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31544

13. Allen, Jessica Lynn. Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition.

Degree: PhD, Mechanical Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-08-5978

► Understanding the underlying coordination mechanisms that lead to a patient’s poor walking performance is critical in developing effective rehabilitation interventions. However, most common measures of… (more)

▼ Understanding the underlying coordination mechanisms that lead to a patient’s poor walking performance is critical in developing effective rehabilitation interventions. However, most common measures of rehabilitation effectiveness do not provide information regarding underlying coordination mechanisms. The overall goal of this research was to analyze the relationship between two potential measures of walking performance (step length asymmetry and module composition) and underlying walking mechanics. Experimental analyses were used to analyze the walking mechanics of hemiparetic subjects grouped by step length asymmetry. All groups had impaired plantarflexor function and the direction of asymmetry provided information regarding the compensatory mechanism used to overcome this plantarflexor impairment. Those subjects who walked with longer paretic than nonparetic steps compensated using increased output from the nonparetic leg, while those with symmetric steps compensated using a bilateral hip strategy. These results suggest that step length asymmetry may provide information regarding underlying coordination mechanisms that can be used to guide rehabilitation efforts. Another way to assess walking performance is to directly analyze deficits in muscle coordination. Recent studies have suggested that complex muscle activity during walking may be generated using a reduced neural control strategy organized around the co-excitation of multiple muscles, or modules, which may provide a useful framework for characterizing coordination deficits. Simulation analyses using modular control were performed to understand how modules contribute to important biomechanical functions of non-impaired walking and how the generation of these functions is altered in groups of post-stroke hemiparetic subjects who commonly merged different sets of non-impaired modules. The non-impaired simulation found that six modules are needed to generate the three-dimensional tasks of walking (support, forward propulsion, mediolateral balance control and leg swing control). When the plantarflexor module was merged with the module controlling the knee extensors and hip abductors, forward propulsion and ipsilateral leg swing were impaired. When the module controlling the hamstrings was merged with the module controlling the knee extensors and hip abductors, forward propulsion, body support and mediolateral balance control were impaired. These results suggest that module analysis may provide useful information regarding the source of walking deficits and can be used to guide rehabilitation efforts. Advisors/Committee Members: Neptune, Richard R. (advisor), Abraham, Lawrence D. (committee member), Barr, Ronald E. (committee member), Deshpande, Ashish D. (committee member), Kautz, Steven A. (committee member).

Subjects/Keywords: Post-stroke hemiparetic walking performance; Forward dynamics simulations; Step length asymmetry; Module composition

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APA (6^th Edition):

Allen, J. L. (2012). Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-08-5978

Chicago Manual of Style (16^th Edition):

Allen, Jessica Lynn. “Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2012-08-5978.

MLA Handbook (7^th Edition):

Allen, Jessica Lynn. “Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition.” 2012. Web. 05 Mar 2021.

Vancouver:

Allen JL. Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-5978.

Council of Science Editors:

Allen JL. Simulation and experimental analyses to assess walking performance post-stroke using step length asymmetry and module composition. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-5978

University of Texas – Austin

14. Montgomery, John Thomas. Investigation and design of an actively actuated lower-limb prosthetic socket.

Degree: MSin Engineering, Mechanical Engineering, 2009, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2009-12-603

► A prosthetic socket worn by an amputee must serve a wide variety of functions, from stationary support to the transfer of forces necessary to move.… (more)

Subjects/Keywords: Prosthetic; Socket; SLS; Selective laser sintering; Pressurization; Bladder; Liner; Membrane; Rapid manufacture; Rapid prototype; Amputee; Residual limb

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APA (6^th Edition):

Montgomery, J. T. (2009). Investigation and design of an actively actuated lower-limb prosthetic socket. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2009-12-603

Chicago Manual of Style (16^th Edition):

Montgomery, John Thomas. “Investigation and design of an actively actuated lower-limb prosthetic socket.” 2009. Masters Thesis, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2009-12-603.

MLA Handbook (7^th Edition):

Montgomery, John Thomas. “Investigation and design of an actively actuated lower-limb prosthetic socket.” 2009. Web. 05 Mar 2021.

Vancouver:

Montgomery JT. Investigation and design of an actively actuated lower-limb prosthetic socket. [Internet] [Masters thesis]. University of Texas – Austin; 2009. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-603.

Council of Science Editors:

Montgomery JT. Investigation and design of an actively actuated lower-limb prosthetic socket. [Masters Thesis]. University of Texas – Austin; 2009. Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-603

University of Texas – Austin

15. Silverman, Anne Katherine. Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-08-1706

► Unilateral, below-knee amputees have altered gait mechanics, which can significantly affect mobility. For example, amputees often have asymmetric leg loading as well as higher metabolic… (more)

▼ Unilateral, below-knee amputees have altered gait mechanics, which can significantly affect mobility. For example, amputees often have asymmetric leg loading as well as higher metabolic cost and an increased risk of falling compared to non-amputees. Below-knee amputees lose the functional use of the ankle muscles, which are critical in non-amputee walking for providing body support, forward propulsion and leg-swing initiation. The ankle muscles also regulate angular momentum in non-amputees, which is important for providing body stability and preventing falls. Thus, compensatory mechanisms in amputee walking are developed to accomplish the functional tasks normally provided by the ankle muscles. In Chapters 2 and 3, three-dimensional forward dynamics simulations of amputee and non-amputee walking were generated to identify compensatory mechanisms and their effects on joint loading and metabolic cost. Results showed that the prosthesis provided body support, but did not provide sufficient body propulsion or leg-swing initiation. As a result, compensations by the residual leg gluteus maximus, gluteus medius, and hamstrings were needed. The simulations also showed the intact leg tibio-femoral joint contact impulse was greater than the residual leg and that the vasti and hamstrings were the primary contributors to the joint impulse on both the intact and residual legs. The amputee simulation had higher metabolic cost than the non-amputee simulation, which was primarily due to prolonged muscle activity from the residual leg gluteus maximus, gluteus medius, hamstrings, vasti and intact leg vasti and ankle muscles. In Chapter 4, whole-body angular momentum in amputees and non-amputees was analyzed. Reduced residual leg propulsion resulted in a smaller range of sagittal plane angular momentum in the second half of the gait cycle. Thus, to conserve angular momentum, reduced braking was needed in the first half of the gait cycle. Decreased residual leg braking appears to be an important mechanism to regulate sagittal plane angular momentum in amputee walking, but was also associated with a greater range of angular momentum that may contribute to reduced stability in amputees. These studies have provided important insight into compensatory mechanisms in below-knee amputee walking and have the potential to guide rehabilitation methods to improve amputee mobility. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E. (committee member), Dingwell, Jonathan B. (committee member), Fernandez, Benito (committee member), Longoria, Raul G. (committee member).

Subjects/Keywords: Transtibial amputee; Biomechanics; Gait; Forward dynamics simulation; Musculoskeletal modeling; Fall risk; Muscle function; Walking speed

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Silverman, A. K. (2010). Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-08-1706

Chicago Manual of Style (16^th Edition):

Silverman, Anne Katherine. “Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2010-08-1706.

MLA Handbook (7^th Edition):

Silverman, Anne Katherine. “Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum.” 2010. Web. 05 Mar 2021.

Vancouver:

Silverman AK. Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1706.

Council of Science Editors:

Silverman AK. Compensatory mechanisms in below-knee amputee walking and their effects on knee joint loading, metabolic cost and angular momentum. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1706

University of Texas – Austin

16. Rankin, Jeffery Wade. The influence of altering wheelchair propulsion technique on upper extremity demand.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-08-1564

► Most manual wheelchair users will experience upper extremity injury and pain during their lifetime, which can be partly attributed to the high load requirements, repetitive… (more)

▼ Most manual wheelchair users will experience upper extremity injury and pain during their lifetime, which can be partly attributed to the high load requirements, repetitive motions and extreme joint postures required during wheelchair propulsion. Recent efforts have attempted to determine how different propulsion techniques influence upper extremity demand using broad measures of demand (e.g., metabolic cost). However studies using more specific measures (e.g., muscle stress), have greater potential to determine how altering propulsion technique influences demand. The goal of this research was to use a musculoskeletal model with forward dynamics simulations of wheelchair propulsion to determine how altering propulsion technique influences muscle demand. Three studies were performed to achieve this goal. In the first study, a wheelchair propulsion simulation was used with a segment power analysis to identify muscle functional roles. The analysis showed that muscles contributed to either the push (i.e. delivering handrim power) or recovery (i.e. repositioning the hand) subtasks, with the transition period between the subtasks requiring high muscle co-contraction. The high co-contraction suggests that future studies focused on altering transition period biomechanics may have the greatest potential to reduce upper extremity demand. The second study investigated how changing the fraction effective force (i.e. the ratio of the tangential to total handrim force, FEF) influenced muscle demand. Simulations maximizing and minimizing FEF both had higher muscle work and stress relative to the nominal simulation. Therefore, the optimal FEF value appears to balance increasing FEF with minimizing upper extremity demand and care should be taken when using FEF to reduce demand. In the third study, simulations of biofeedback trials were used to determine the influence of cadence, push angle and peak handrim force on muscle demand. Although minimizing peak force had the lowest total muscle stress, individual stresses of many muscles were >20% and the simulation had the highest cadence, suggesting that this variable may not reduce demand. Instead minimizing cadence may be most effective, which had the lowest total muscle work and slowest cadence. These results have important implications for designing effective rehabilitation strategies that can reduce upper extremity injury and pain among manual wheelchair users. Advisors/Committee Members: Neptune, Richard R. (advisor), Barr, Ronald E. (committee member), Fernandez, Benito R. (committee member), Dingwell, Jonathan B. (committee member), Richter, William M. (committee member).

Subjects/Keywords: Upper extremity; Upper extremity pain; Wheelchair propulsion; Musculoskeletal model; Biomechanics; Wheelchairs; Fraction effective force; Biofeedback

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rankin, J. W. (2010). The influence of altering wheelchair propulsion technique on upper extremity demand. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-08-1564

Chicago Manual of Style (16^th Edition):

Rankin, Jeffery Wade. “The influence of altering wheelchair propulsion technique on upper extremity demand.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2010-08-1564.

MLA Handbook (7^th Edition):

Rankin, Jeffery Wade. “The influence of altering wheelchair propulsion technique on upper extremity demand.” 2010. Web. 05 Mar 2021.

Vancouver:

Rankin JW. The influence of altering wheelchair propulsion technique on upper extremity demand. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1564.

Council of Science Editors:

Rankin JW. The influence of altering wheelchair propulsion technique on upper extremity demand. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1564

University of Texas – Austin

17. Peterson, Carrie Lynn, 1981-. Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-08-1623

► Stroke is the leading cause of long term disability with improved walking being an important goal following stroke. Understanding deficits that result in reduced walking… (more)

▼ Stroke is the leading cause of long term disability with improved walking being an important goal following stroke. Understanding deficits that result in reduced walking performance by hemiparetic subjects is important for the design of effective rehabilitation strategies. The goal of this research was to investigate muscle coordination and mechanical work in hemiparetic walking and mechanisms of acceleration and deceleration in nondisabled walking as a framework for investigating non-steady state walking in hemiparetic subjects. Musculoskeletal modeling and simulation analyses were used to compare individual muscle contributions to important walking subtasks and muscle mechanical work by representative hemiparetic subjects (limited community and community walkers) during pre-swing with a representative speed and age-matched control. Simulation analyses identified decreased paretic soleus and gastrocnemius contributions to forward propulsion and power generation as the primary impairment in the limited community walker compared to the control. Comparison of mechanical work showed that total paretic and non-paretic fiber work was increased in the limited community walker, which was primarily related to decreased fiber and tendon work by paretic soleus and gastrocnemius. The decreased output by the ankle plantar flexors required compensatory work by other muscles. Also, the experimental analyses of accelerated and decelerated walking showed that the ankle plantar flexor moment was positively related to braking and propulsive impulses, which increased with speed. Thus, deficits of the paretic plantar flexors limit forward propulsion and increase mechanical work during pre-swing, and would limit the ability of hemiparetic walkers to accelerate and decelerate, which are essential tasks in daily living activities. For the community walker, simulation analyses showed that deficits in paretic swing initiation are a primary impairment. Specifically, the paretic gastrocnemius and hip flexors contributed less to swing initiation in the community walker compared to the control subject. Total paretic and non-paretic fiber work was increased in the community walker, primarily due to increased work by the hip abductors and adductors. Because step length and step frequency were positively related to walking speed in accelerated and decelerated walking, impaired paretic swing initiation would likely limit the community walker’s ability to accelerate and decelerate. Advisors/Committee Members: Neptune, Richard R. (advisor), Abraham, Lawrence D. (committee member), Barr, Ronald E. (committee member), Kautz, Steven A. (committee member), Longoria, Raul G. (committee member).

Subjects/Keywords: Biomechanics; Walking; Muscle work; Acceleration

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APA (6^th Edition):

Peterson, Carrie Lynn, 1. (2010). Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-08-1623

Chicago Manual of Style (16^th Edition):

Peterson, Carrie Lynn, 1981-. “Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2010-08-1623.

MLA Handbook (7^th Edition):

Peterson, Carrie Lynn, 1981-. “Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait.” 2010. Web. 05 Mar 2021.

Vancouver:

Peterson, Carrie Lynn 1. Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1623.

Council of Science Editors:

Peterson, Carrie Lynn 1. Simulation and experimental analyses of human movement : application to post-stroke hemiparetic gait. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1623

University of Texas – Austin

18. Ventura, Jessica Dawn. Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-05-786

► Over one million amputees are living in the United States with major lower limb loss (Ziegler-Graham et al. 2008). Lower limb amputation leads to the… (more)

Subjects/Keywords: Biomechanics; Below-knee amputee; Prosthetic feet; Prosthetic ankle; Joint kinetics; Ground reaction forces; Muscle activity; Gait mechanics; Forward dynamics simulation; Transtibial amputees; Amputee gait mechanics; Prosthetics; Artificial limbs

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ventura, J. D. (2010). Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-05-786

Chicago Manual of Style (16^th Edition):

Ventura, Jessica Dawn. “Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/ETD-UT-2010-05-786.

MLA Handbook (7^th Edition):

Ventura, Jessica Dawn. “Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics.” 2010. Web. 05 Mar 2021.

Vancouver:

Ventura JD. Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-786.

Council of Science Editors:

Ventura JD. Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-786

University of Texas – Austin

19. Krishnamoorthy, Ganesh. A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems.

Degree: PhD, Mechanical Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/19572

► Electromechanical Actuators (EMAs) are being increasingly used in many applications. There is a need to augment good design of EMAs with continuous awareness of their… (more)

▼ Electromechanical Actuators (EMAs) are being increasingly used in many applications. There is a need to augment good design of EMAs with continuous awareness of their operational capability and make them ‘intelligent’ for two key objectives: enhancing performance to address exigent task requirements and to track any changes from their ‘as-built and certified’ state for condition-based maintenance. These objectives are achieved using a decision making philosophy where the human system operator supervises EMA operation using performance criteria and decision surfaces; updated by in-situ measurement of the variables of interest via a suite of diverse sensors. However, operational decisions made on the basis of faulty data could result in unwelcome consequences. With unexpected variations in a sensor’s output from its anticipated values, the challenge is to determine if it indicates a problem in the sensor or the monitored system. In addressing this conundrum, it is also essential to account for the inherent uncertainties present in the values being analyzed. To this end, this dissertation presents the development of a novel Sensor and Process Fault Detection and Isolation (SPFDI) algorithm. This provides a framework to utilize data from all the available sensors in a holistic manner to detect any faults in individual sensors or the system components concurrently. The algorithm uses a Bayesian network to model a system; populated with extensive empirical data. The probabilistic foundations of this method allow for incorporating and propagating uncertainties. The construction of a modular testbed and its Bayesian network are discussed in detail. Several design/ operational criteria have been proposed to aid in the creation of more usable networks in the future. The SPFDI algorithm estimates multiple values for each measurand using different combinations of input variables and probabilistic inferencing. These values are compared against those indicated by the corresponding sensors; a difference between them is indicative of a potential problem. Quantitative indicators to track the condition of different system components and sensors, termed as belief values, are modified after each comparison. The final belief values obtained at the end of an iteration of the algorithm provide a definitive indication of the sources of anomalies in the observed data and can provide guidance to the operator on decisions such as whether or not to use data from a particular sensor for updating existing decision surfaces. The representative examples and experimental results confirm the efficacy of the algorithm in detecting and isolating single as well as multiple sensor faults. The algorithm has also been found to be capable of distinguishing between sensor and system/process faults. Special categories of faults and factors that influence the execution characteristics and quality of results from the algorithm were also explored meticulously and suitable modifications have been suggested to enable the algorithm to continue to function… Advisors/Committee Members: Tesar, Delbert (advisor), Ashok, Pradeepkumar (committee member), Barr, Ronald E (committee member), Crawford, Richard H (committee member), Djurdjanovic, Dragan (committee member), Hooper, Richard (committee member).

Subjects/Keywords: Bayesian network; Design and operational criteria; Sensor and Process Fault Detection and Isolation (SPFDI)

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Krishnamoorthy, G. (2010). A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/19572

Chicago Manual of Style (16^th Edition):

Krishnamoorthy, Ganesh. “A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed March 05, 2021. http://hdl.handle.net/2152/19572.

MLA Handbook (7^th Edition):

Krishnamoorthy, Ganesh. “A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems.” 2010. Web. 05 Mar 2021.

Vancouver:

Krishnamoorthy G. A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/2152/19572.

Council of Science Editors:

Krishnamoorthy G. A Framework for Utilizing Data from Multiple Sensors in Intelligent Mechanical Systems. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/19572

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