Matching Items (43,917)
Description
Thermal interface materials (TIMs) are extensively used in thermal management applications especially in the microelectronics industry. With the advancement in microprocessors design and speed, the thermal management is becoming more complex. With these advancements in microelectronics, there have been parallel advancements in thermal interface materials. Given the vast number of available TIM types, selection of the material for each specific application is crucial. Most of the metrologies currently available on the market are designed to qualify TIMs between two perfectly flat surfaces, mimicking an ideal scenario. However, in realistic applications parallel surfaces may not be the case. In this study, a unique characterization method is proposed to address the need for TIMs characterization between non-parallel surfaces. Two different metrologies are custom-designed and built to measure the impact of tilt angle on the performance of TIMs. The first metrology, Angular TIM Tester, is based on the ASTM D5470 standard with flexibility to perform characterization of the sample under induced tilt angle of the rods. The second metrology, Bare Die Tilting Metrology, is designed to validate the performance of TIM under induced tilt angle between the bare die and the cooling solution in an "in-situ" package testing format. Several types of off-the-shelf thermal interface materials were tested and the results are outlined in the study. Data were collected using both metrologies for all selected materials. It was found that small tilt angles, up to 0.6°, have an impact on thermal resistance of all materials especially for in-situ testing. In addition, resistance change between 0° and the selected tilt angle was found to be in close agreement between the two metrologies for paste-based materials and phase-change material. However, a clear difference in the thermal performance of the tested materials was observed between the two metrologies for the gap filler materials.
Contributors
Harris, Enisa (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Devasenathipathy, Shankar (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Accounts in the media often demonize teachers and misrepresent what is happening in schools. Meanwhile, teachers' voices are largely absent from the national and international debates on school reform. This dissertation privileges the voices of nine participating Kindergarten through second grade teachers from a variety of public schools, including affluent schools and schools receiving full and partial Title I funding. Through observations and interviews teachers shared their narratives of classroom joys and challenges while also describing how policy has affected these experiences. A preliminary discourse analysis of these narratives was performed, identifying narratives related to nodes of the activity system of schooling. Further discourse analysis of these identified narratives revealed how these teachers' classroom experiences position them within an activity system strongly influenced by tensions between maternal relationships and the patriarchal project of schooling. A critical feminist theoretical perspective is utilized to respond to these tensions and to describe possibilities for future studies in education and the future of education in general.
Contributors
Gaches, Sonya (Author) / Swadener, Elizabeth B (Thesis advisor) / Sandlin, Jennifer (Committee member) / Gee, James (Committee member) / Arizona State University (Publisher)
Created
2011
Description
As clarinet compositions created by Taiwanese composers have not been widely discussed and published in academia, this research paper examines three unaccompanied clarinet works by three Taiwanese composers: Ballade by Hsiao-Wen Tseng, Chin Thoughts III by Ling-Huei Tsai, and Pointe de Flame by Chia-Lin Pan, all commissioned by the author in 2007. This research also includes a compact disc with recordings of these works, aiming to document the creativity of Taiwanese composers. This research paper examines these three commissioned works by analyzing their overall musical styles, notations, formal structures, rhythmical and melodic materials, unconventional clarinet techniques as well as the influence of Chinese musical elements. The analysis reveals the distinctive characteristic of each piece. Moreover, the author provides composers' insights and performance guides to help interested readers practice these pieces. To further understand how the composers create these pieces by drawing upon different life experiences, the paper also includes information about their backgrounds, program notes, lists of compositions, and music examples for reference. The author found that collaborating with these composers helped to establish a closer composer-performer relationship in interpreting the music. It is hoped that this compact disc recording will help make Taiwanese composers' clarinet works more accessible to a wider audience. Moreover, this research paper hopes to generate more interest in performing and appreciating music composed by Taiwanese composers.
Contributors
Chuang, Yenting (Author) / Spring, Robert (Thesis advisor) / Schuring, Martin (Committee member) / Campbell, Andrew (Committee member) / Jiang, Danwen (Committee member) / Hackbarth, Glenn (Committee member) / Arizona State University (Publisher)
Created
2011
Description
ABSTRACT A hallmark of Arizona schools is the choice of parents in program and school for their child under the Open Enrollment laws. Among the choices for parents at some schools is Dual Language education, a form of enrichment wherein students learn the content of the Arizona State Standards through the medium of their primary language and a second language. The schools of this study use English and Spanish as the two languages. After 13 years of existence, changes in enrollment patterns have been noticed. Some parents whose older children attended Dual Language classes have chosen to dis-enroll their families from the program, so that their younger children are in English Only classes. At the same time that these trends in enrollment began, so too did strict enactment, enforcement, and monitoring of Arizona's Structured English Immersion program, the Department of Education's response to the voter approved Proposition 203--English for the Children--in November 2000. This study asks the following research question of de-selecting parents involved with Dual Language programs in Phoenix, Arizona: What are the rationale that influence parents to de-select Dual Language instruction in Arizona public schools in 2010 after having selected Dual Language for their older child(ren)? The study uses a Latino Critical Race Theory (LatCrit) Conceptual Framework to analyze interviews of 10 parents and 2 administrators from Dual Language programs in Phoenix, Arizona. There are three general findings of the study: 1) Parents sought asymmetrical measures of program design if their children were struggling in one language more than another, and chose to de-select when these asymmetrical measures were not enacted, 2) the de-selection process was generally not the result of family decision making, but rather reactionary to a situation, and 3) legislative mandates resulted in de-selection of the program. The LatCrit perspective showed most strongly in the third of these, wherein the de-selection was not necessarily a result of parent de-selection of the program, but rather the state's de-selection of willing participants in a language learning option. The hopes of the study are to hear the voices of parents who have to negotiate language policies and make programmatic choice decisions for their children. I also hope to provide information that Dual Language schools can use to understand the motivations and perspectives of the parents that will enable them to strengthen their programs and advocate for equality in opportunity for enrichment language programs for all children at their schools.
Contributors
Robert, Michael Anthony (Author) / Ovando, Carlos J (Thesis advisor) / Fischman, Gustavo E (Committee member) / Mccarty, Teresa L (Committee member) / Arizona State University (Publisher)
Created
2011
Description
This dissertation presents a systematic study of the sorption mechanisms of hydrophobic silica aerogel (Cabot Nanogel®) granules for oil and volatile organic compounds (VOCs) in different phases. The performance of Nanogel for removing oil from laboratory synthetic oil-in-water emulsions and real oily wastewater, and VOCs from their aqueous solution, in both packed bed (PB) and inverse fluidized bed (IFB) modes was also investigated. The sorption mechanisms of VOCs in the vapor, pure liquid, and aqueous solution phases, free oil, emulsified oil, and oil from real wastewater on Nanogel were systematically studied via batch kinetics and equilibrium experiments. The VOC results show that the adsorption of vapor is very slow due to the extremely low thermal conductivity of Nanogel. The faster adsorption rates in the liquid and solution phases are controlled by the mass transport, either by capillary flow or by vapor diffusion/adsorption. The oil results show that Nanogel has a very high capacity for adsorption of pure oils. However, the rate for adsorption of oil from an oil-water emulsion on the Nanogel is 5-10 times slower than that for adsorption of pure oils or organics from their aqueous solutions. For an oil-water emulsion, the oil adsorption capacity decreases with an increasing proportion of the surfactant added. An even lower sorption capacity and a slower sorption rate were observed for a real oily wastewater sample due to the high stability and very small droplet size of the wastewater. The performance of Nanogel granules for removing emulsified oil, oil from real oily wastewater, and toluene at low concentrations in both PB and IFB modes was systematically investigated. The hydrodynamics characteristics of the Nanogel granules in an IFB were studied by measuring the pressure drop and bed expansion with superficial water velocity. The density of the Nanogel granules was calculated from the plateau pressure drop of the IFB. The oil/toluene removal efficiency and the capacity of the Nanogel granules in the PB or IFB were also measured experimentally and predicted by two models based on equilibrium and kinetic batch measurements of the Nanogel granules.
Contributors
Wang, Ding (Author) / Lin, Jerry Y.S. (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Westerhoff, Paul (Committee member) / Nielsen, David (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created
2011
Description
In 2005, the Navajo Sovereignty in Education Act was signed into law by the Navajo Nation. Like the No Child Left Behind Act, this Navajo Nation legislation was as much a policy statement as it was a law. It marked the first time that the Navajo Nation linked sovereignty with education by expressing its intent to control all education within its exterior boundaries. The objective of the law was to create a department of education that would resemble the states of Arizona, New Mexico, and Utah in which the Navajo Nation resides. Through their department of education, the Navajo Nation would operate the educational functions for its populace. This study looked at the implications and impact that perspectives of this law would have on public schools within Arizona from the perspective of five superintendents in Arizona public schools within the Navajo Nation were gained through open-ended interviews. It examined the legal, fiscal, and curricular issues through the prism of sovereignty. Through the process of interviews utilizing a set of guided questions in a semi-structured format, five superintendents in Arizona public schools within the Navajo Nation shared their perspectives. Analysis of the five interviews revealed curriculum, funding, jurisdictional, and fear or mistrust as problems the Navajo Nation will need to overcome if it is to begin full control of all aspects of education within its boundaries. There is a strong need for the Department of Dine' Education to educate public schools with regards to the Navajo Nation Sovereignty in Education Act of 2005. Administrators need more training in tribal governments. Like the constitution, the Navajo Sovereignty in Education Act will be interpreted differently by different people. But, without action, it will be ignored. Within the Act's pages are the hopes of the Navajo Nation and the dreams for our young Navajo students.
Contributors
Roessel, Karina A (Author) / Appleton, Nicholas (Thesis advisor) / Spencer, Dee Ann (Thesis advisor) / Wauneka, Jacquelyne (Committee member) / Arizona State University (Publisher)
Created
2011
Description
The flow around a golf ball is studied using direct numerical simulation (DNS). An immersed boundary approach is adopted in which the incompressible Navier-Stokes equations are solved using a fractional step method on a structured, staggered grid in cylindrical coordinates. The boundary conditions on the surface are imposed using momentum forcing in the vicinity of the boundary. The flow solver is parallelized using a domain decomposition strategy and message passing interface (MPI), and exhibits linear scaling on as many as 500 processors. A laminar flow case is presented to verify the formal accuracy of the method. The immersed boundary approach is validated by comparison with computations of the flow over a smooth sphere. Simulations are performed at Reynolds numbers of 2.5 × 104 and 1.1 × 105 based on the diameter of the ball and the freestream speed and using grids comprised of more than 1.14 × 109 points. Flow visualizations reveal the location of separation, as well as the delay of complete detachment. Predictions of the aerodynamic forces at both Reynolds numbers are in reasonable agreement with measurements. Energy spectra of the velocity quantify the dominant frequencies of the flow near separation and in the wake. Time-averaged statistics reveal characteristic physical patterns in the flow as well as local trends within dimples. A mechanism of drag reduction due to the dimples is confirmed, and metrics for dimple optimization are proposed.
Contributors
Smith, Clinton E (Author) / Squires, Kyle D (Thesis advisor) / Balaras, Elias (Committee member) / Herrmann, Marcus (Committee member) / Adrian, Ronald (Committee member) / Stanzione, Daniel C (Committee member) / Calhoun, Ronald (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Over the past century in the southwestern United States human actions have altered hydrological processes that shape riparian ecosystems. One change, release of treated wastewater into waterways, has created perennial base flows and increased nutrient availability in ephemeral or intermittent channels. While there are benefits to utilizing treated wastewater for environmental flows, there are numerous unresolved ecohydrological issues regarding the efficacy of effluent to sustain groundwater-dependent riparian ecosystems. This research examined how nutrient-rich effluent, released into waterways with varying depths to groundwater, influences riparian plant community development. Statewide analysis of spatial and temporal patterns of effluent generation and release revealed that hydrogeomorphic setting significantly influences downstream riparian response. Approximately 70% of effluent released is into deep groundwater systems, which produced the lowest riparian development. A greenhouse study assessed how varying concentrations of nitrogen and phosphorus, emulating levels in effluent, influenced plant community response. With increasing nitrogen concentrations, vegetation emerging from riparian seed banks had greater biomass, reduced species richness, and greater abundance of nitrophilic species. The effluent-dominated Santa Cruz River in southern Arizona, with a shallow groundwater upper reach and deep groundwater lower reach, served as a study river while the San Pedro River provided a control. Analysis revealed that woody species richness and composition were similar between the two systems. Hydric pioneers (Populus fremontii, Salix gooddingii) were dominant at perennial sites on both rivers. Nitrophilic species (Conium maculatum, Polygonum lapathifolium) dominated herbaceous plant communities and plant heights were greatest in effluent-dominated reaches. Riparian vegetation declined with increasing downstream distance in the upper Santa Cruz, while patterns in the lower Santa Cruz were confounded by additional downstream agricultural input and a channelized floodplain. There were distinct longitudinal and lateral shifts toward more xeric species with increasing downstream distance and increasing lateral distance from the low-flow channel. Patterns in the upper and lower Santa Cruz reaches indicate that water availability drives riparian vegetation outcomes below treatment facilities. Ultimately, this research informs decision processes and increases adaptive capacity for water resources policy and management through the integration of ecological data in decision frameworks regarding the release of effluent for environmental flows.
Contributors
White, Margaret Susan (Author) / Stromberg, Juliet C. (Thesis advisor) / Fisher, Stuart G. (Committee member) / White, Dave (Committee member) / Holway, James (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Economic development over the last century has driven a tripling of the world's population, a twenty-fold increase in fossil fuel consumption, and a tripling of traditional biomass consumption. The associated broad income and wealth inequities are retaining over 2 billion people in poverty. Adding to this, fossil fuel combustion is impacting the environment across spatial and temporal scales and the cost of energy is outpacing all other variable costs for most industries. With 60% of world energy delivered in 2008 consumed by the commercial and industrial sector, the fragmented and disparate energy-related decision making within organizations are largely responsible for the inefficient and impacting use of energy resources. The global transition towards sustainable development will require the collective efforts of national, regional, and local governments, institutions, the private sector, and a well-informed public. The leadership role in this transition could be provided by private and public sector organizations, by way of sustainability-oriented organizations, cultures, and infrastructure. The diversity in literature exemplifies the developing nature of sustainability science, with most sustainability assessment approaches and frameworks lacking transformational characteristics, tending to focus on analytical methods. In general, some shortfalls in sustainability assessment processes include lack of: * thorough stakeholder participation in systems and stakeholder mapping, * participatory envisioning of future sustainable states, * normative aggregation of results to provide an overall measure of sustainability, and * influence within strategic decision-making processes. Specific to energy sustainability assessments, while some authors aggregate results to provide overall sustainability scores, assessments have focused solely on energy supply scenarios, while including the deficits discussed above. This paper presents a framework for supporting organizational transition processes towards sustainable energy systems, using systems and stakeholder mapping, participatory envisioning, and sustainability assessment to prepare the development of transition strategies towards realizing long-term energy sustainability. The energy system at Arizona State University's Tempe campus (ASU) in 2008 was used as a baseline to evaluate the sustainability of the current system. From interviews and participatory workshops, energy system stakeholders provided information to map the current system and measure its performance. Utilizing operationalized principles of energy sustainability, stakeholders envisioned a future sustainable state of the energy system, and then developed strategies to begin transition of the current system to its potential future sustainable state. Key findings include stakeholders recognizing that the current energy system is unsustainable as measured against principles of energy sustainability and an envisioned future sustainable state of the energy system. Also, insufficient governmental stakeholder engagement upstream within the current system could lead to added risk as regulations affect energy supply. Energy demand behavior and consumption patterns are insufficiently understood by current stakeholders, limiting participation and accountability from consumers. In conclusion, although this research study focused on the Tempe campus, ASU could apply this process to other campuses thereby improving overall ASU energy system sustainability. Expanding stakeholder engagement upstream within the energy system and better understanding energy consumption behavior can also improve long-term energy sustainability. Finally, benchmarking ASU's performance against its peer universities could expand the current climate commitment of participants to broader sustainability goals.
Contributors
Buch, Rajesh (Author) / Wiek, Arnim (Thesis advisor) / Basile, George (Thesis advisor) / Williams, Eric (Committee member) / Arizona State University (Publisher)
Created
2011
Description
Barrett, The Honors College at Arizona State University (ASU) serves as a universal role model for organizing the resources of an institution to support highly motivated and prepared students. In 2009, Barrett, The Honors College (Barrett) opened the nation's first purposefully designed undergraduate honors residential college campus. Given the current demand by other American higher education institutions who wish to better understand how Barrett emerged as a distinct and singular model for an honors residential college experience, this action research study explores the effectiveness of the decisions, execution and outcomes central to Barrett's development. Five senior administrators of college units or universities were interviewed and provided insight for constructing a design for how other honors programs and colleges can learn from the challenges and accomplishments presented in developing an honors college for the 21st century while replicating Barrett's success. The study is framed in the overall context of how Barrett actualizes the New American University at ASU in meeting the demand for producing students that can compete in a global marketplace.
Contributors
Hermann, Kristen (Author) / Ewing, Kris M (Thesis advisor) / Rund, James (Committee member) / Hesse, Marian (Committee member) / Arizona State University (Publisher)
Created
2011