Digital Commons Network^™

Friction Stir Channeling: An Innovative Technique For Heat Exchanger Manufacturing, Nagarajan Balasubramanian

Doctoral Dissertations

"Friction stir processing (FSP) is an emerging processing technique based on the principles of friction stir welding (FSW), which is a relatively new solid-state metal joining process developed by The Welding Institute, UK. Some of the unique features of FSW such as the low amount of heat generated, extensive plastic deformation and controlled flow of material is being exploited to develop new material modification and manufacturing processes. Friction stir channeling (FSC) is one such adaptation of FSP that can produce continuous and stable internal channels for application in heat exchanging equipment. Friction stir channeling produces these channels if the defect …

Addressing Nonlinear Combustion Instabilities In Highly Dilute Spark Ignition Engine Operation, Brian C. Kaul

Doctoral Dissertations

"Dilute operation is a promising approach for increasing spark-ignition engine efficiency, in the form of either lean burn (air dilution) or EGR (inert dilution). High levels of charge dilution, however, lead to cyclic variability that is largely deterministic in nature. The determinism and nonlinear nature of the system indicate that it should be possible to reduce the cycle-to-cycle variations by implementing an electronic controller. Several needs arise when considering the development of such a controller. Three topics of interest are covered herein. First, a method of analysis for nonlinear dynamical systems is applied to engine data in order to estimate …

Business-Oriented Software Process Improvement Based On Cmm And Cmmi Using Qfd, Yan Sun

Doctoral Dissertations

"Software Process Improvement (SPI) has become the key to the survival of many software development organizations. Many international SPI models/standards are developed for SPI. The Capability Maturity Model (CMM) and Capability Maturity Model Integrated (CMMI)) from the Software Engineering Institute are two SPI models. In this study, several existing SPI models and approaches are reviewed, their advantages are identified, and their drawbacks are discussed. A set of new SPI frameworks integrating Quality Function Deployment (QFD) with both CMM and CMMI are developed by combining the best features of previous approaches and addressing their limitations"--Abstract, page iii.

Physical Modeling Of Railroad Ballast Using The Parallel Gradation Scaling Technique Within The Cyclical Triaxial Framework, Adam F. Sevi

Doctoral Dissertations

"Due to the difficulties involved with testing large particle granular materials such as rockfill and railroad ballast, several methods of testing scaled down model specimens have been introduced. Of these techniques, the parallel gradation model has been found to be most useful. The parallel gradation model states that a smaller grainsize distribution model granular material, of the same composition as the prototype material, can be used in triaxial testing at a scaled down grainsize, if the model materials grainsize is exactly parallel to the prototype material. Therefore, a model granular material composed of a smaller, but parallel, grainsize distribution can …

A Tour-De-Force In Polymer Crosslinked Aerogels, Sudhir Mulik

Doctoral Dissertations

"In the quest of building mechanically strong materials with low density and high porosity, polymer crosslinked aerogels stand as the most promising nano-engineered examples. Covalent attachment of polymers and bridging of skeletal nanoparticles of typical aerogels is demonstrated by using surface initiated polymerization (SIP) with a bidentate free-radical initiator structurally related to azobisisobutyronitrile (AIBN) and confined on mesoporous silica surfaces. Different monomers were introduced in the mesopores and upon heating at 70⁰C, all mesoporous surfaces throughout the entire skeletal framework were coated conformally with a 10-12 nm thick polymer layer indistinguishable spectroscopically from the respective commercial bulk materials. The new …

Virtual Prototyping With Surface Reconstruction And Freeform Geometric Modeling Using Level-Set Method, Weihan Zhang

Doctoral Dissertations

"More and more products with complex geometries are being designed and manufactured by computer aided design (CAD) and rapid prototyping (RP) technologies. Freeform surface is a geometrical feature widely used in modern products like car bodies, airfoils and turbine blades as well as in aesthetic artifacts. How to efficiently design and generate digital prototypes with freeform surfaces is an important issue in CAD. This paper presents the development of a Virtual Sculpting system and addresses the issues of surface reconstruction from dexel data structures and freeform geometric modeling using the level-set method from distance field structure. Our virtual sculpting method …

A Comparison Of Alternating Minimization And Expectation Maximization Algorithms For Single Source Gamma Ray Tomography, R. Varma, S. Bhusarapu, J. A. O'Sullivan, M. (Muthanna) H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Lange and Carson (1984 J. Comput. Assist. Tomogr. 8 306-16) Defined Image Reconstruction for Transmission Tomography as a Maximum Likelihood Estimation Problem and Derived an Expectation Maximization (EM) Algorithm to Obtain the Maximum Likelihood Image Estimate. However, in the Maximization Step or M-Step of the EM Algorithm, an Approximation is Made in the Solution Which Can Affect the Image Quality, particularly in the Case of Domains with High Attenuating Material. O'Sullivan and Benac (2007 IEEE Trans. Med. Imaging 26 283-97) Reformulated the Maximum Likelihood Problem as a Double Minimization of an I-Divergence to Obtain a Family of Image Reconstruction Algorithms, …

Effect Of Hydrodynamic Multiplicity On Trickle Bed Reactor Performance, Werner Van Der Merwe, Willie Nicol, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Multiple Hydrodynamic States in Trickle Bed Reactors Have Been the Subject of Numerous Hydrodynamic Investigations. the Extent of Variation in the Hydrodynamic Parameters (Like Holdup and Pressure Drop) is Large and This Variation Can Be Expected to Have a Significant Impact on the Conversion in a Reaction System. This Study Presents Reaction Data for Α-Methyl Styrene Hydrogenation in a Trickle Bed Reactor over a Range of Conditions that Include Gas and Liquid Limitations. It is Seen that Liquid Flow Rate Variation Induced Hysteresis Has a Large Impact on the Conversion. for Gas-Limited Reactions, the Upper Branch of the Pressure Drop …

Glass Transition Behavior Of Poly(Methyl Acrylate) End-Grafted By Atrp To Amorphous Silica, Manikantan B. Nair, Frank D. Blum

Chemistry Faculty Research & Creative Works

Ultra-thin polymer films attached to solid substrates (supported films) have attracted significant interest in recent years. Supported films are used in the design of advanced materials like photoresists, lubricants and other electronic devices. Glass transition temperatures (Tgs) of supported polymer films have also been of significant interest. The Tg has been shown to depend on the thickness of the polymer film on the surface and the inherent nature of the surface. The effect of end-grafting of a polymer chain to a surface, on the Tg of the polymer has been studied previously.1 Reports on the study of glass transition behaviors …

Polyaniline Nanofiber-Based Gas Sensors, Zhe-Fei Li, Frank D. Blum, Massimo F. Bertino, Chang-Soo Kim

Chemistry Faculty Research & Creative Works

There has been recent interest in conducting polymers that have very promising chemical and electrical applications. Some of these polymers have shown great potential for use in sensors.1 Polyaniline is one particular example of a prospective material. In our laboratory, we have studied the synthesis of polyaniline nanofibers. We have carried out one-pot syntheses to obtain polyaniline nanofibers in aqueous solutions where the polymerization was influenced by γ-radiation2 or UV-radiation.3 This polymer can also be patterned with an appropriate photo mask. In our present report, polyaniline nanofiber thin film sensors have been fabricated in one step by employing UV-irradiation and …

Assemblies Of Nanoparticles As 3d Scaffolds For New Materials Design: From Polymer Crosslinked Aerogels To Polymer Matrix Composites, Nicholas Leventis, Chariklia Sotiriou-Leventis, Sudhir Mulik, Vishal U. Patil, Dhairyashil Mohite, Yanli Zhang, Hongbing Lu

Chemistry Faculty Research & Creative Works

From a materials perspective, nanotechnology furnishes materials with useful macroscopic properties by manipulating matter in the 1-100 nm size regime. Improvements in performance in terms of strength, modulus and wetability are accomplished by, for example, introducing nanoparticles as fillers in plastics . Two issues that usually interfere with optimal materials performance are agglomeration of the nanoparticles and materials compatibility. Agglomeration cancels the advantage of using nanoparticulate matter as dopant, while lack of materials compatibility introduces a discontinuity at the polymer/dopant interface from where failure may begin. Agglomeration is encountered with surfactants that keep nanoparticles dispersed, while materials compatibility is improved …

Dynamics Of Adsorbed Pma-D₃ - Effect Of Substrate, Frank D. Blum, Burak Metin, Macduff O. Okuom

Chemistry Faculty Research & Creative Works

In the last few years, our group has focused much of our attention on studying the dynamics of polymers adsorbed at interfaces. Much of our work, to date has been on labeled poly(vinyl acetate)-d3 (PVAc-d3)1 and poly(methyl acrylate)-d3 (PMA-d3)2 on silica. We have been able to probe the effects of adsorbed amount,3 molecular mass,4,5 and the effect of overlayer.6 These studies have provided a view of the adsorbed polymer consistent with a motional gradient in the layer with the more mobile segments being those at the air-polymer interface and the less-mobile segments at the substratepolymer interface. However, we have not …

Dynamics Of Pipa-D₇ On Silica Surface, Piyawan Krisanangkura, Frank D. Blum

Chemistry Faculty Research & Creative Works

Molecular motion of polymer chains is an important determinant in understanding the physical properties of polymeric materials. Glass transition temperature (Tg) is a physical property of polymers, which is of primary interest. The study of the dynamics of polymer segments assists in understanding the dependence of Tg on polymer structure.1 For decades, studies have addressed the molecular motion in various polymers. Some of them have probed the dynamics of polymer backbones.2,3 the properties of a polymer at an interface may change because of the type of polymer, the substrate, or other variables. The side chain of a polymer can also …

This Piece Is A Coverup, Clayton James Webber

Graduate Student Theses, Dissertations, & Professional Papers

"This Piece is a Coverup" follows Ben from his days as a club kid to his role in one of the most notoriously violent prison gangs in the US.

Traps: Stories And A One-Act Play, James Blanks

Graduate Student Theses, Dissertations, & Professional Papers

A collection of five short stories and a one-act play.

Enabling Wind Turbine Generators To Participate In Power Grid Frequency Regulation For Enhanced Stability, Hongtao Ma

Doctoral Dissertations

"This dissertation focuses on wind farm frequency regulation capability to maintain the grid frequency stability. Wind plant power controllers are designed and tested for participation in grid frequency restoration. The small signal stability on sub-optimal operating points is analyzed and a de-loaded operating point is proposed.

In the first paper, a new frequency regulation scheme is developed for the wind turbine/generator/converter trio that will provide the capability to participate in restoring frequency in a way similar to the droop response of conventional generators. Output active power adjustment can be realized by both converter and pitch angle control in addition to …

Causes And Consequences Of The Postfire Increase In Deer Mouse (Peromyscus Maniculatus) Abundance, Rafal Pawel Zwolak

Graduate Student Theses, Dissertations, & Professional Papers

Wildfire triggers an increase in deer mouse (Peromyscus maniculatus) abundance. Here, I describe this phenomenon, investigate its causes, and explore the consequences of the postfire increase in mice for conifer recruitment in burned forest. I documented a shift in small mammal communities away from more specialized species such as red-backed voles (Myodes gapperi) and shrews (Sorex spp.) and towards greater abundance of generalist deer mice after a wildfire in montane forest. I conducted a meta-analysis of published studies on the abundance of small mammals in disturbed versus undisturbed forests and established that the pattern of increased deer mouse abundance holds …

Prior Pidginization And Creolization In Moroccan Arabic, Kennetta Kathleen Aune

Graduate Student Theses, Dissertations, & Professional Papers

This thesis makes a claim about the processes of prior pidginization and creolization, and a process of current decreolization in Moroccan Arabic (a colloquial dialect of Arabic spoken in Morocco). The claim of this thesis is based on the theory of pidginization and creolization in Arabic as posited by Versteegh (1984). A case-study is built for the aforementioned processes having occurred in Moroccan Arabic through fulfillment of Southworth’s (1971) two principles for determining the credibility of a pidginization and/or creolization claim: (1) That the required socio-linguistic frameworks are in place, and (2) that the linguistic effects of such processes are …

Producing A Biblical Atlas, Elizabeth Anne Hertz

Graduate Student Theses, Dissertations, & Professional Papers

The purpose of this thesis was to develop a procedure for simplifying the production of a biblical atlas. The atlas was to be designed specifically for those people interested in the geography of the Bible, and looking at the themes and events in the Bible in a spatial way. The procedures used in developing the contents involved the use of interviews with different experts and reviewing different biblical atlases. Telephone and email interviews were given to twelve experts to gain information about producing a biblical atlas. The participants in the interviews were selected based upon their knowledge of the specific …

Community Based Epidemiological Study Of Chagas Disease In Rural Peru, Paul Walker

Yale Medicine Thesis Digital Library

The purpose of this study was to evaluate the epidemiology of Trypanosoma cruzi infection, to valuate the TESA blot, and to characterize cardiac findings of patients with Chagas disease in a rural setting near Arequipa, Peru. The study site was the town of Quequeña, Peru with a population of 774 with 236 inhabitants under the age of 18 according to the 2005 census conducted by Peru. A fumigation/insect collection campaign was done in December of 2006 to quantify household infestation levels, document housing characteristics, and GPS household locations. Of the 602 people surveyed to be living in Quequeña, blood samples …

A Phonological Description Of Wichí: The Dialect Of Misión La Paz, Salta, Argentina, Megan Leigh Zdrojkowski Avram

Master's Theses and Doctoral Dissertations

The Wichí language, a member of the Matacoan language family, is spoken in parts of South America’s Chaco region. Specifically, Wichí is found in the Salta, Chaco, and Formosa provinces of Argentina, as well as in southeastern Bolivia. Wichí is an endangered language, with speakers numbering c. 25,000 (although estimates vary greatly). This study aims to contribute to the documentation of Wichí and to our understanding of human language in general by providing insight into the phonetics and phonology of the dialect of Wichí spoken in the remote village of Misión La Paz, Salta, Argentina. The data for this study …

A Union Of Gender Equality And Pragmatic Patriarchy: International Marriages And Citizenship Laws In Singapore, Eugene K. B. Tan

Research Collection Yong Pung How School Of Law

As a patriarchal society, government policies, societal norms and government regulations in Singapore mirror that normative ideal. Citizenship status and rights along gender lines, manifested in the legal recognition of children of international marriages, reflected this reality for much of Singapore's independence. However, the onslaught of globalization, the rise in international marriages, disconcerting declining birth rates, and an acceptance of 'foreign talent' have given the economic imperative and demographic impulse to grant citizenship (by descent) to a person born outside Singapore whose father or mother is a citizen of Singapore, by birth, registration or descent. Previously, such a person would …

The Xhosa And The Truth And Reconciliation Commission: African Ways, Douglas H.M. Carver

Tribal Law Journal

The author begins by providing a conceptual framework for indigenous people generally and then focuses on indigenous people in South Africa. Mr. Carver then discusses the culture and customs of the Xhosa, one of the main ethnic groups from the Republic of South Africa. He then discusses the Truth and Reconciliation Commission (TRC), set up in South Africa after the fall of the apartheid regime, which was meant to rebuild a society divided by racial and ethnic lines. The author explains how the Xhosa concept of "ubuntu" – encompassing African concepts of justice, harmony and reconciliation — became a core …

Shadow War Scholarship, Indigenous Legal Tradition, And Modern Law In Indian Country, Christine Zuni Cruz

Tribal Law Journal

In this essay, Tribal Law Journal Editor-in-Chief Zuni Cruz comments on the purpose of the Tribal Law Journal. She borrows the term "shadow war" from the Zapatistas' use of the Internet as she describes the Journal's endeavor to make Indigenous law explicit and to promote mental sovereignty. She challenges and invites others who write about the law of Indigenous Peoples to join in making legal scholarship in this area accessible to the public, especially the Indigenous public, and to create a depository of thought, rejecting the scattering of thought, by publishing legal scholarship in the global, publicly accessible e-journal, that …

Continuous Source Of Care Among Young Underserved Children: Associated Characteristics And Use Of Recommended Parenting Practices., Esther K Chung, Leny Mathew, Kelly F Mccollum, Irma T Elo, Jennifer F Culhane

Department of Pediatrics Faculty Papers

OBJECTIVES: The aim of this study was to 1) assess sociodemographic and health characteristics associated with having a continuous source of care (CSOC) among young children and 2) determine the relationship between having a CSOC and use of parenting practices.

METHODS: We conducted a prospective, community-based survey of women receiving prenatal care at Philadelphia community health centers. We conducted surveys at the first prenatal visit and at a mean age +/- standard deviation of 3 +/-1, 11 +/- 1, and 24 +/- 2 months postpartum, obtaining information on sociodemographic and health characteristics, child's health care provider, and 6 parenting practices. …

Floristic Records In The Platte And Loup River Bottomlands Of Platte County, Nebraska, Michael P. Gutzmer, Robert B. Kaul

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

A recent inventory of vascular plants in the Loup and Platte riverbottoms in Platte County has greatly increased knowledge of the area's flora. Of the 542 species of vascular plants now known to grow in the county, 289 were discovered after 1977, with more than 100 of those after 1990. 425 native and 117 naturalized species are known so far. Nearly 700 native and naturalized alien species are expected to occur in the county, based upon totals from nearby counties. Thus, almost 150 years after European settlement, more than 20% of the species remain unverified; of those, many are undoubtedly …

The Meaning Of Place And Community In Contemporary Educational Discourse, John Siskar, Paul Theobald

Journal of Inquiry and Action in Education

Place and community are terms used with ever more frequency in discussions, reports, and research related to education, yet there is little agreement related to what these terms mean. This article examines the concepts of place and community in an attempt to bring more clarity to the role they may play in educational theory and, ultimately, educational policy.

Privacy And Funeral Protests, Christina E. Wells

Faculty Publications

This article examines the free speech implications of funeral protest statutes. Enacted in response to the Westboro Baptist Church, whose members protest at funerals to spread their antigay message, such statutes restrict a broad array of peaceful expressive activity. This Article focuses on the states’ interest underlying these statutes - protecting mourners’ right to be free from unwanted intrusions while at funeral services. Few would argue against protecting funeral services from intrusive protests. These statutes, however, go far beyond that notion and protect mourners from offensive, rather than intrusive, protests. As such, they do not conceive of privacy as protection …

Prosecuting Aggression, Noah Weisbord

Faculty Publications

The Assembly of States Parties to the International Criminal Court will soon have its first opportunity to revise the Rome Statute and activate the latent crime of aggression, which awaits a definition of its elements and conditions for the exercise of jurisdiction. The working group charged with drafting a provision is scheduled to complete its task by 2008 or 2009, one year before the International Criminal Court’s first review conference.

Beginning with a history of the crime meant to put the current negotiations in the context of past initiatives, this article sets out the status of the negotiations and begins …

(Mis)Appropriated Liberty: Identity, Gender Justice And Muslim Personal Law Reform In India, Cyra Akila Choudhury

Faculty Publications

This article argues that in order to emancipate Indian-Muslim women from an outdated family legal code, their position at the intersection of gender and a minority religion must be taken seriously. Proposals for reform that have been suggested by Western liberal, secular feminists that ignore the importance of women's religious affiliation fail to do this. Moreover, by making assumptions about the strength of secularism in India, the willingness of the state to enact legal reforms driven by gender concerns, and by failing to acknowledge the limits of formal rights alone in changing norms, these scholars do not account for the …