Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
4 results
Search Results
Item LARGE MOTION VISUALIZATION AND ESTIMATION FOR FLAPPING WING SYSTEMS(2015) Hsu, Tzu-Sheng; Balachandran, Balakumar; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. Motion capture of a free flying insect is considered by using three synchronized high-speed cameras. A solid finite element representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. An objective function is formulated, and various shape difference definitions are considered. The proposed methodology is first studied for a synthetic case of a flexible cantilever structure undergoing large deformations, and then applied to a Manduca Sexta (hawkmoth) in free flight. The three-dimensional motions of this flapping system are reconstructed from image date collected by using three cameras. The complete deformation geometry of this system is analyzed. Finally, a computational investigation is carried out to understand the flow physics and aerodynamic performance by prescribing the body and wing motions in a fluid-body code. This thesis work contains one of the first set of such motion visualization and deformation analyses carried out for a hawkmoth in free flight. The tools and procedures used in this work are widely applicable to the studies of other flying animals with flexible wings as well as synthetic systems with flexible body elements.Item Transforming Together: Reconsidering Adaptive Reuse(2013) Crenshaw, Emma Elizabeth; Noonan, Peter; Simon, Madlen; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis examines the evolving and transforming relationship between building and community. It is a study of the past and present of a community and its architecture in order to propose an adaptive plan for a place that involves the adaptive reuse of a historic building. Utilizing theory related to vernacular architecture, critical regionalism and phenomenology, a framework for study is applied to a case study. Peckham, a district in South London in England, and one of its former industrial buildings, the Bussey Building, serves as the case-study. Peckham is home for a mixed "fringe" community that is in a process of transformation that is linked to the area's industrial past. In order to explore sustainability in a more holistic and human way, this thesis posits a question: Can architects design buildings to adapt to a continually changing situation, physically mapping the relationship between architecture and community over time?Item Industrial Flexibility in Theory and Practice(2009) Reindorp, Matthew; Fu, Michael; Goyal, Manu; Business and Management: Decision & Information Technologies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)At the heart of any decision problem is some degree of "flexibility" in how to act. Most often, we aim to extract greatest possible value from this inherent flexibility. The three essays compiled here are aligned with this same general aim, but we have an important secondary concern: to highlight the value of flexibility itself in the various situations we study. In the first essay, we consider the timing of an action: when to replace obsolete subsystems within an extensive, complex infrastructure. Such replacement action, known as capital renewal, must balance uncertainty about future profitability against uncertainty about future renewal costs. Treating renewal investments as real options, we derive the unique, closed-form optimal solution to the infinite horizon version of this problem and determine the total present value of an institution's capital renewal options. We investigate the sensitivity of the solution to variations in key problem parameters. The second essay addresses the promising of lead times in a make-to-order environment, complicated by the need to serve multiple customer classes with differing priority levels. We tackle this problem with a "model free" approach: after preparing a discrete-event simulation of a make-to-order production system, we determine a policy for lead time promising through application of a reinforcement learning algorithm. The third essay presents an empirical analysis of new product launches in the automotive industry, showing that manufacturing flexibility is one key indicator of superior productivity during launch. We explore the financial dimensions of the apparent productivity differences and show that the use of flexible manufacturing increases an automobile plant's likelihood of being chosen to host a new product launch.Item Understanding Dynamic Capabilities at the Subunit Level: Operational Flexibility and the Crucial Role of Organization Design and Information Sharing(2004-11-24) Gardner, Sharyn; Stevens, Cynthia K.; Faraj, Samer A.; Management and Organization; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Organizations are currently facing increasingly dynamic environments that require fast action in high-velocity settings. Recent research on dynamic capabilities purports that organizations need to build these capabilities to successfully confront increasing uncertainty. Among these capabilities, authors suggest that flexibility may be a key ingredient needed to adapt to uncertainty and change. Yet, a review of the literature reveals that there is a gap that neglects subunit level activities at the lower levels of the firm, and thus it is difficult to determine how to build flexibility at this level. In this study, I examined key factors related to operational flexibility, defined as the ability of subunits to change day-to-day or within a day with the operational problems and changes. Utilizing organizational design, information theory, and organizational learning theory, I developed and tested a model of subunit design factors and information sharing relationships with operational flexibility and in turn subunit performance. I conducted a national field study of emergency departments in level I and II trauma centers examining these relationships. Data were collected from 110 trauma centers throughout multiple levels in the emergency department within each participating organization. Using hierarchical regression analysis, results indicate that subunit design factors and information timeliness and accessibility are significantly related to operational flexibility. Additional analyses further show that these subunit design factors are also related to subunit performance. Results also indicated that operational flexibility was not related to subunit performance, yet a combined operational flexibility index was. The findings contribute to the emerging field of dynamic capabilities by establishing operational flexibility as one of these important qualities at the subunit level. Second, this study furthers research at the meso or subunit level of the organization supporting the notion that organizational functioning is a combination of micro and macro concepts as well as contextual issues. Moreover, the results help identify possible antecedents of operational flexibility, yet fall short of empirically linking the separate dimensions with performance. Finally, the field setting of this dissertation provides a distinct contribution through the examination of concepts in a rarely studied setting: emergency departments in level I and II trauma centers.