Browsing by Subject "Modeling and simulation"
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Item Muscle function and coordination of amputee and non-amputee stair ascent(2015-08) Harper, Nicole Guckert; Neptune, Richard R.; Barr, Ronald E; Deshpande, Ashish D; Sulzer, James S; Wilken, Jason MStair 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.Item Thermal-electrical co-simulation of shipboard integrated power systems on an all-electric ship(2009-08) Pruske, Matthew Andrew; Kiehne, Thomas M.; Seepersad, Carolyn C.The goal of the work reported herein has been to model aspects of the electrical distribution system of an all-electric ship (AES) and to couple electrical load behavior with the thermal management network aboard the ship. The development of a thermally dependent electrical network has built upon an in-house thermal management simulation environment to replace the existing steady state heat loads with dynamic, thermally dependent, electrical heat loads. Quantifying the close relationship between thermal and electrical systems is of fundamental importance in a large, integrated system like the AES. This in-house thermal management environment, called the Dynamic Thermal Modeling and Simulation (DTMS) framework, provided the fundamental capabilities for modeling thermal systems and subsystems relevant to the AES. The motivation behind the initial work on DTMS was to understand the dynamics of thermal management aboard the ship. The first version, developed in 2007, captured the fundamental aspects of system-level thermal management while maintaining modularity and allowing for further development into other energy domains. The reconfigurable nature of the DTMS framework allowed for the expansion into the electrical domain with the creation of an electrical distribution network in support of thermal simulations. The dynamics of the electrical distribution system of the AES were captured using reconfigurable and physics-based circuit elements that allow for thermal feedback to affect the behavior of the system. Following the creation of the electrical network, subsystems and systems were created to simulate electrical distribution. Then, again using the modularity features of DTMS, a thermal resistive heat flow network was created to capture the transient behavior of heat flow from the electrical network to the existing thermal management framework. This network provides the intimate link between the thermal management framework and the electrical distribution system. Finally, the three frameworks (electrical, thermal resistive, and thermal management) were combined to quantify the impact that each system has relative to system-level operation. Simulations provide an indication of the unlimited configurations and potential design space a user of DTMS can explore to explore the design of an AES.