This dissertation explores the formation and significance of the screenscape in popular culture. A screenscape encompasses the mixture of screens and bodies that enter into and transform the aesthetic quality of social space. After reviewing types of screens that might comprise a given screenscape, I approach the screen not only as a technology but a cultural form that influences the way audiences perceive the relationship between media and their environments. As such, I expand Brian Massumi's reading of the production of fear through the television after 9/11 and argue that the screen is a space of and for the collective modulation of affect. My argument hinges on three interlocking concepts: the screen as threshold, the affective body, and the biopolitical population. While new media theorists Lev Manovich and Anne Friedberg position the screen as a frame for onscreen content, the first chapter concludes by outlining how the screen also functions as a threshold, a critical point or site of transition. The second chapter defines the affective body and biopolitical population, linking the two through the collective modulation of affect. Each of the final three chapters focuses on a specific example, weaving together the concepts of the screen as threshold, affective body, and biopolitical population through the construction of the screenscape. I analyze the television series Dollhouse as a metaphor of the screen as a threshold. The narrative positions the primary character, Echo (Eliza Dushku), as a screen ' a site for display rather than an object on display. She simultaneously represents both the affective body and the biopolitical population. Next I turn to Nine Inch Nail's Lights in the Sky tour. Trent Reznor, the visionary behind Nine Inch Nails, stands for the fantasy of the artist who surrenders his body to the onstage screenscape he finances and designs. Reznor's playful interactions with the three 'stealth' screens enable his body to be controlled and secured by the logic of the screenscape as it expands beyond his control. My final discussion takes an ethnographic approach to the study of the screen at the 2008 US Open in New York. This sporting attraction and entertainment spectacle brings together a variety of screens ranging from video boards to handheld televisions. Here, the enormity of the event is expressed through the personal, affective relationships people have with their screen technologies. At the same time, the arrangement of screens across the venue help to manage crowds, control access, and corporately brand an event in its becoming. These readings hinge on a paradox embedded in the screen as a cultural form: to enter into the screenscape means to affect and be affected by the biopolitical population as it weaves into and informs the logic of cultural production and consumption. / A Dissertation submitted to the Program in Interdisciplinary Humanities in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2010. / March 26, 2010. / Includes bibliographical references. / Amit Rai, Professor Directing Dissertation; Andy Opel, University Representative; Leigh Edwards, Committee Member; Kathleen Yancey, Committee Member.

The United States has long had traditions of both religious and secular millenarian anticipation as well as violent rebellions against political authority. From the Cold War forward, these formerly separate aspects of American culture have begun to coalesce, using the language of anti-communism and isolationism as the basis for an end times discourse that predicts the subordination of the United States' national and cultural sovereignty to a sinister, trans-national world system. This conspiracy-driven description of a globally integrated system is predicted to act as an obstacle, subverting the United States' divine destiny as a country chosen to lead the world while maintaining separation from other nations. In recent decades, changes in the United States' sexual, racial, and other cultural hierarchies have increased these conspiratorial and millenarian fears, prompting ultra-conservatives to use the widely disseminated anti-communist templates of the Cold War to describe social changes that they have attributed to nefarious foreign influence as well as domestic collaboration from othered elites. In response to such changes, which have been mythologized as precursors to far more oppressive measures by a global system commonly referred to as the New World Order, violent armed groups have arisen, seeking to combat the hidden forces presumed to have orchestrated the cultural changes that they view as an agenda of disenfranchisement and persecution. Apocalyptic and millenarian movements are generally associated with social responses to observable disasters such as famine, war, or economic depression. However this is not the case with the millenarian movements of the American far-right. Through an analysis of these groups' end times fictions (the novels that depict slippery slopes from which perceived social ills lead to the extremity of persecution) the issues that make up the core concerns of American ultra-conservatives are not objective, observable disasters, they are the outcome of cultural alienation at the loss of white privilege and threats to patriarchy. Analysis of the American far-right's end times fiction reveals a literary genre that has evolved from the Cold War's anti-communist hysteria and has since been adapted to address social, political, and economic trends of concern to conservatives ranging from the civil rights era to contemporary trends in the globalization of political and economic institutions. These novels function as foundational fictions ' they seek to define the national spirit as well as its demographic and cultural constitution. Using the form of apocalyptic narrative, this national revitalization is portrayed as the outcome of the violent elimination of the Other to establish a monolithic nation variously characterized as singularly white or Christian in the most extreme examples, but always ultra-conservative and evoking an anti-federalist 'constitutional' or extreme libertarian attitude towards governmental authority. In recent decades there have been numerous cases that demonstrate the influence that far-right apocalyptic fictions have had on acts of domestic terrorism. Furthermore, these texts and their conspiratorial underpinnings have led to the mainstreaming of millenarian scripts: cues by which current events might be interpreted as indicative of an impending apocalyptic singularity. This singularity is a point of no return that, if properly anticipated and reacted against, might allow members of such an interpretive community to pre-empt the end-times disaster and ensure that the emerging millenarian world is a utopia of their own creation. The dissemination of conspiratorial themes and their ideological assumptions have been mainstreamed by the entertainment and conservative media, making these frames available to audiences beyond the extremist fringes and therefore, making the understanding of these texts and their ability to act as lenses through which the world is understood all the more important. / A Dissertation submitted to the Program in Interdisciplinary Humanities in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2010. / November 24, 2009. / Includes bibliographical references. / Will Moore, Professor Directing Dissertation; David Johnson, University Representative; Max Friedman, Committee Member; Maricarmen Martinez, Committee Member; Barney Warf, Committee Member.

A novel electrochemical cell design based on yarn or fiber-like carbon nanotube electrodes was developed as an engineered solution for flexible electrochemical devices, namely electrical energy storage devices. Proof-of-concept cells consisting of porous CNT networks as the sole structural support, electronic conductor and active charge storage material were fabricated and tested. The coaxial yarn cell provided a robust structure able to undergo flexural deformation with minimal impact on the energy storage performance. Greater than 95% of the energy density and 99% of the power density was retained when wound around an 11 cm diameter cylinder. The electrochemical properties were characterized at stages throughout the fabrication process to provide insights and potential directions for further development of these novel cell designs. To demonstrate the ability to improve the performance and extend the applicability of the CNT network based cell design to various cell chemistries and material combinations, the versatile redox activity material vanadium oxide (VOx) was deposited onto CNT yarns. A supercritical fluid deposition and in-situ oxidation process was utilized to create thin conformal coatings of vanadium oxide on carbon nanotube (CNT) surfaces throughout the porous structure of CNT yarns. Half-cell electrochemical characterizations were conducted on carbon nanotube-vanadium oxide (CNT-VOx) yarn electrodes in an 8 M LiCl aqueous electrolyte. The high surface area, interconnected pore structure and high electrical conductivity of the CNT yarn enabled extraordinary rate capabilities from the high capacity Li/VOx system. Cyclic voltammetry tests with scan rates of several volts per second, requiring current densities of hundreds of amperes per gram of electrode mass produced voltammograms with distinguishable redox peaks from Li-ion intercalation/deintercalation. Capacitances of over 150 F g-1 were achieved at a scan rate of 5 V s-1 over a 1.2 V potential window resulting in an energy density of > 32 Wh kg-1 (> 30 Wh L-1) for the yarn electrode. The charge storage also showed good reversibility when cycled over this large potential window, maintaining 90% of the capacitance after 100 cycles at a scan rate of 2 V s-1. Investigation into the structure-property relationship of the CNT yarn and the effects on electrochemical energy storage performance was conducted through half-cell testing of single-filament CNT yarn electrodes. Electrochemical impedance spectroscopy (EIS) enabled the development of an equivalent circuit model based on representation of the CNT yarn through a parallel configuration of a constant phase element (CPE) and Warburg impedance element. Various physical properties of the electrode and electrode-electrolyte system can be obtained from model fitting of the experimental data, providing the ability to verify model accuracy through the comparison of known physical properties (e.g. electrode resistivity), as well as the ability to gain insight into complex electrochemical phenomena from previously unmeasured properties. Analysis of the modeling results for the DC potential dependent EIS tests on electrodes of various lengths suggest a relationship between the effective ion diffusion lengths, the extent of mobile charge carries in the CNT electronic structure and the fractal dimension of the hierarchical self-similar CNT yarn electrodes. The unique concentric cylinder architecture of the flexible coaxial electrode cells displayed an unintended sensitivity of the cell open-circuit voltage (OCV) to the atmosphere surrounding the cell; specifically to changes in the relative humidity. This potentiostatic responsiveness from the coaxial cell was characterized experimentally and a hypothesis was developed relating the OCV response to humidity to the chemical potential energy that exists upon the establishments of concentration (activity) gradients. The Nersnt relation was used to provide quantitative support of the hypothesis through the development of a time-dependent model of the OCV response to the relative humidity. Finite element methods were used to approximate the 1D solution to Fick's diffusion laws to model the H₂O transport through the polymer electrolyte membrane and calculate the time-varying water concentration profile. The model results provide strong support of the hypothesis that the open-circuit voltage response is based on the time-dependent concentration gradient of water between the inner and outer electrodes of the coaxial cell. These results have implications for applications such as humidity sensors, wearable energy harvesting, and self-powered detection devices. / A Dissertation submitted to the Materials Science and Engineering Program in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2014. / November 7, 2014. / Includes bibliographical references. / Zhiyong Liang, Professor Directing Dissertation; Tao Liu, Committee Member; Jim Zheng, Committee Member; Steven Lenhert, Committee Member.

A novel ceramic-polymer hybrid composite is fabricated by co-curing lay-up process to combine a carbon nanotube (CNT) reinforced ceramic composite film with a carbon fiber reinforced polymer (CFRP) composite substrate. A transition layer made of non-woven carbon fiber tissues and both ceramic and polymeric matrices are introduced to improve the bonding strength of CNT ceramic composite and CFRP. Volume fraction of CNTs in the CNT ceramic composite is variable from 30% to 60% depending on the CNT preform employed. 6K T300 carbon fiber 2×2 plain weave fabric reinforced bismaleimide (BMI) composites are used as the CFRP substrate. The hybrid composite has good structural integrity with a pull-off bonding strength up to 8.3 MPa. Microstructures are characterized to investigate the bonding mechanism. Ceramic and polymeric matrices are evenly distributed and interlocked each other by the carbon fibers in the transition layer. Carbon fibers in the transition layer bond to the CNT ceramic composite and CFRP tightly with the help of the ceramic or polymeric matrices. Flexural fatigue, heating-cooling thermal fatigue and wet-conditioning test are fulfilled to investigate the structural stability. The hybrid composite developed maintains good properties stability after these tests. Thermal properties of the hybrid composite are studied by both theoretical simulation and experimental method. Micro-hardness test is taken to characterize the surface hardness of the hybrid composite, CFRP and bulk ceramics. Microstructure analysis of the indentation dent confirms that the hybrid composite shares the same mechanical response to micro-hardness test as the bulk ceramics. Sandblasting test in accordance with ASTM C418-12 is applied on both CFRP and the hybrid composite. The CNT ceramic composite layer of the hybrid composite is effective protecting the CFRP substrate from erosions. Microstructure of the sandblasted surfaces is characterized to analyze the failure mode. The erosion resistance mechanism of the hybrid composite is discussed. / A Dissertation submitted to the Materials Science and Engineering Program in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2018. / April 9, 2018. / bonding, ceramic matrix composite, CFRP, Hybrid composite / Includes bibliographical references. / Cheryl Xu, Professor Co-Directing Dissertation; Eric Hellstrom, Professor Co-Directing Dissertation; Peng Xiong, University Representative; Richard Liang, Committee Member; Zhibin Yu, Committee Member; Chen Huang, Committee Member.

As wireless devices become more prevalent, the radio frequency (RF) spectrum is becoming more densely populated with cell phone and internet related broadband activities (e.g. text messaging, web browsing, and wireless routing). This feasibility study presents a sensitivity study on how location, use of an antenna and motion may impact the ability to measure RF power density for specific frequencies. The RF power obtained from a nearby radio station was compared to the relative RF power available for frequencies understudy. The results of the study indicated that 2.4 GHz is significant in terms of prevalence and power density which allows for technological opportunity and caution due to potential health hazards. Optimization of a 2D inductor is also presented and which makes it easier for RF inductor designers to selectively choose the dimensions and number of turns of the inductor based on the desired inductance and power. / A Dissertation submitted to the Department of Industrial Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2007. / May 22, 2007. / RF, Radio Frequency, Inductor, Energy, Inductance, Harvesting, Power / Includes bibliographical references. / Yaw A. Owusu, Professor Co-Directing Dissertation; Samuel A. Awoniyi, Professor Co-Directing Dissertation; Mark H. Weatherspoon, Outside Committee Member; Okenwa I. Okoli, Committee Member.

No description available.

Diblock copolymer self-assembly of materials is emerging as a key element in the fabrication of functional nanostructured materials. By solvent casting or solvent annealing block copolymer thin films, we have demonstrated methods to produce diblock copolymer films with highly oriented, close-packed arrays of nanoscopic cylindrical domains with a high degree of long-range lateral order with few defects. The solvent imparts a high degree of mobility in the microphase-separated copolymer that enables a rapid removal of defects and a high degree of lateral order. Though the use of a selective cosolvent during solvent casting, it was found that the microdomain size and spacing could be increased, leading to a size-tunable system. Additionally, the presence of water also led to the ability to control the microdomain orientation during solvent annealing. Ionic complexation within cylinder-forming PS- b-EO block copolymer thin films was also investigated, where added salts bind PEO block as the minor component. Small amounts of added salts, on the order a few ions per chain, show large effects on the ordering of the copolymer films during solvent annealing. By using gold or cobalt salts, well-organized patterns of nanoparticles can be generated in the copolymer microdomains. Topographically and chemically patterned surfaces were used as a route to sectorizing and controlling the lattice orientation of copolymer films. Topographically patterned surfaces allow well-defined boundaries to confine the copolymer microdomains on a surface and effectively direct the ordering and grain orientation of the copolymer microdomains. Chemically patterned surfaces provide a route to direct the block copolymer ordering on completely flat surface, which may have advantages in applications where adding additional topography may be undesirable. To generate nanoporous templates from PS-b-PEO bases materials several routs were followed. The first route was through the addition and selective solvent removal of homopolymer PEO or PMMA. Second, we have incorporated a center block that is photodegradable by ultra violet radiation into PS- b-PMMA-b-PEO copolymers. Third, a tritylether junction was placed between the two blocks, which is cleavable by exposure to trifluoroacetic acid vapor. Though the use of solvents in block copolymer thin films, were are able to markedly enhance the long range lateral ordering block copolymer films. Also, routes to sectorize surfaces to confine and direct the copolymer microdomains are shown. Also, three methods to generate nanoporous films from PS-b-PEO based copolymers are demonstrated. All of these results are important in the realization of addressable media from block copolymer nanolithography.

This study concerns the characterization of platinum nickel (PtNi) and platinum vanadium (PtV) near-surface alloys (NSAs) for use as improved catalysts in proton exchange membrane hydrogen fuel cells. The need for this study arose in order to further understand the principles behind the predicted catalytic properties of NSAs, to fabricate them and to characterize them experimentally. Two groups of NSAs were fabricated, namely PtNi and PtV. Pt was used as the parent metal while Ni and V were used as the solute/near surface constituents. Within these groups of pt with Ni or V, variations in coating thickness and heat treatments were used to attempt to fabricate the NSA structure. Surface profile analysis was carried out using profilometry and light microscopy. These techniques showed that surfaces were not always of a 100% mirror finish and that deposited coatings were not stable and were prone to peeling especially with coatings of greater than one layer. Elemental analysis was performed by employing energydispersive x-ray spectroscopy (SEM-EDS), proton induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS). These techniques helped verify the presence of the thin deposited coatings whilst also highlighting the presence of contaminants in the form of iron, manganese and chromium. Tafel Plot analysis was used to gather electrochemical data for the NSAs. In this regard, the hydrogen reduction (evolution) reaction was analyzed with the exchange current density extracted experimentally therefrom. This technique confirmed that Pt is indeed a superior catalyst, especially compared to pure Ni and V. It showed that ebeam deposition did not create coated systems which were suitable for Tafel analysis. It also illustrated that deaeration via nitrogen gas was not always effective with trace oxygen sometimes being present in the purge gas, resulting in contaminant oxygen reduction distorting the electrochemical results. Ultimately, electron-beam deposition proved to be inefficient in fabricating stable coatings for catalysis, with the coatings possibly not being adequately thin to mimic the NSA structure. This, coupled with trace oxygen reduction, prevented effective analysis of NSA catalytic properties.

It has been well established that most fatigue cracks initiate from stress concentration sites found on the surfaces of components subject to cyclic fatigue loading. The introduction of residual compressive stresses into the surface layers of components, through various means including shot peening and laser shock peening, can result in local residual compressive stresses which provide a resistance to both crack initiation and propagation, thus leading to an increase in the fatigue life of the components. The effects of both laser shock peening (LSP) and conventional shot peening (SP) on the fatigue properties of both 7075-T6 and 7075-T0 aluminium round bar test specimens were investigated and compared by means of cyclic 3-point bend fatigue testing. This investigation focused on the role that the peening induced microstructure, surface morphology and hardness had on the fatigue life of the test specimens. It was found that both the laser shock peening and shot peening processes substantially increased the fatigue lives compared to unpeened AA7075-T6. The laser shock peening process more than doubled the fatigue life of the specimens and the shot peening process increased the fatigue life by approximately 1.6×. No discernible hardening effects could be determined in the laser shock peened specimens. However, the shot peening process resulted in a distinct hardened region within the surface layers of the AA7075-T6 specimens which was attributed to the longer pressure duration of the shot peening process which results in greater plastic deformation. It was also shown that polishing the shot peened and laser shock peened specimens after their respective peening procedures resulted in a significant increase in fatigue life. Polishing after peening resulted in a 3.4× fatigue life increase in the shot peened test specimens (T6 condition) and a 5.4× fatigue life increase in the laser shock peened test specimens (T6 condition). This result highlights the role that surface roughness plays in component fatigue life. Furthermore, the increase in the average fatigue life of the polished test specimens shows that the depth of the residual compressive stresses induced by the peening processes were deep enough to allow for surfaces layers to be removed from the test specimens without any detrimental effect to the overall average fatigue life of the components. The result also suggests that the magnitudes of the residual stresses induced by the laser shock peening process being greater than those of the shot peening process. The main difference between the peening treatments was demonstrated as originating from the surface roughening effects of the two peening procedures. The laser shock peening process only slightly increased the surface roughness of a polished AA7075-T6 test specimens. The shot peening process severely affected the surface roughness of the test specimens, creating many potential crack initiation sites. The AA7075-O test specimens (annealed) showed no overall improvement in their fatigue life, regardless of the mechanical treatment received. The increased ductility of the specimens during the 3-point bending fatigue process led to stress relieving of the peening induced compressive stresses. The specimens were however still fatigued to failure. This enabled the analysis of the effect of the peening induced surface roughness to be analysed. It was found that the shot peened and laser shock peened surface roughness values were significantly higher than the roughness values of the T6 specimens owing to the increased ductility and thus workability of the test specimens. These increased surface roughnesses resulted in the shot peened test specimens failing before the laser shock peened specimens. Both sets of peened specimens failed before the "as machined" and polished test specimens highlighting the role that their induced surface roughnesses had on their fatigue lives. The cross-sectional microstructures of the peened samples in each material condition showed varied changes in the microstructure of the treated aluminium alloy. There was evidence of a large degree of plastic deformation near the surface of shot peened specimens in both material conditions. However, there was limited evidence of changes to the grains structure of the laser shock peened specimens, in both material conditions. In addition, the ability of the laser shock peening process to recover fatigue life in damaged components was also investigated. This brought into question whether the laser shock peening process can be used on a partially fatigued component at the point of crack initiation, in an attempt to further improve the fatigue life of the component. It was found that the laser shock peening of the cracks initiated in fatigue life recovery process did little to effectively recover fatigue life in the damaged components. A degree of life extension was present as cracks re-initiated after a few thousand cycles and was attributed to crack tip closure. This closure led to a general reduction in the fatigue crack growth rate when compared to laser shock peened/polished test specimens fatigued at the same stress.

Al-Si-Mg casting alloys are being used in automotive applications, aerospace applications and other applications requiring heat-treatable permanent mould castings that combine good weldability with high strength and toughness (ASM). These casting alloys are also known for their excellent castability, corrosion resistance and, in particular, .a range of mechanical properties in the heattreated condition. A357 aluminum alloy has been extensively used for semi-solid processing for more than three decades, and a large amount of components like fuel rails, engine mounts, engine brackets and suspension parts have been produced. This alloy is also included in the Statement for Work between the Council for Scientific and Industrial Research (CSIR) and Boeing Co, USA. F357, a hypo-eutectic aluminium alloy, Al-7%Si-0.6%Mg without beryllium, was processed with CSIR-Rheo technology to the Semi-Solid Metal (SSM) state and cast in plates with a 50 Ton High Pressure Die Casting machine. The castings were either left in the as-cast (F) condition or subjected to T4, T4+ or T6 heat treatments prior to laser welding. Welding of aluminium alloys poses many problems like porosity, loss of alloying elements, poor bead geometry and softening of the heat affected zone. Laser welding is however widely used in industrial production owing to the advantages such as low heat input, high welding speed and high production rate. Due to these unique advantages, the potential of autogenous Nd: Y AG laser welding as manufacturing process for this cast aluminium alloy was evaluated. A welding operating window was established and the optimum parameters were found to be a laser power of 3.8 kW at the workpiece and a welding speed of 4 m/min with a twin spot laser light configuration. These laser welding parameters were applied for the welding of the heat treated plates and resulted in very low weld joint porosity and almost no loss of alloying elements. The mechanical properties of age-hardenable Al-Si-Mg alloys are dependent on the rate at which the alloy is cooled after the solution heat treatment Because of the high cooling rate during laser welding, the possibility of producing weld seams through deep penetration laser welding, with mechanical properties matching those of the T6 temper condition, but without a post-weld solid solution heat treatment, was investigated. The quench rate after laser welding was measured and compared well with that measured after solution treatment. The resulting mechanical properties of F357 aluminium welded in the T4 condition and only artificially aged after welding (T4+ condition), compares very well with the T6 base material properties. The strengthening mechanisms obtained during laser welding and the different heat treatments were studied by means of transmission electron microscopy (TEM) and are consistent with the expected precipitation hardening processes in Al-Si-Mg alloys. The quench sensitivity of SSM F357 aluminium alloy is thus sufficiently low to obtain such an increase in strength values during laser welding, that no postweld solution heat treatment is necessary to achieve mechanical properties to the T6 performance specification.