Influence of fluids on the abrasion of silicon by diamond

Silicon wafers ((100)-p-type) were abraded at room temperature in acetone, absolute ethanol and water by a pyramid diamond and the resulting groove depth was measured as a function of normal force on the diamond and the absorbed fluids, while all other experimental conditions were held constant. The groove depth rates are in the ratio of 1:2:3 for water, absolute ethanol, and acetone, respectively, for a constant normal force. The groove depth rate is lower when the normal force is decreased. The silicon abraded in the presence of water was chipped as expected for a classical brittle material while the surfaces abraded in the other two fluids showed ductile ploughing as the main mechanism for silicon removal

Study of abrasive wear rate of silicon using n-alcohols

The work carried out at the University of Illinois at Chicago for the Flat-Plate Solar Array Project under contract No. 956053 is summarized. The abrasion wear rate of silicon in a number of fluid environments and the parameters that influence the surface mechanical properties of silicon were determined. Three tests were carried out in this study: circular and linear multiple-scratch test, microhardness test and a three-point bend test. The pertinent parameters such as effect of surface orientation, dopant and fluid properties were sorted. A brief review and critique of previous work is presented

Fungible Space: Competition and Volatility in the Global Logistics Network

This article examines an emerging form of interspatial competition premised on attracting cargo traffic and value‐added logistics activities. Against the backdrop of economic globalization and the revolution in logistics, place‐based actors are increasingly vying to insert their localities into transnational supply chains. I explore the causes, conditions and consequences of this burgeoning growth strategy through a study of the dynamics surrounding the expansion of the Panama Canal, opened to shipping traffic in June 2016, and the consequent battle among North American ports to attract a new generation of oversized container vessels. The spatial practices of mobile actors in the logistics industry, I argue, represent the leading edge of capitalism's tendency to render places interchangeable—a condition I call fungible space. The abstract logic of spatial substitution, however, can never fully escape the concrete qualities of particular places, which form the very conditions of interchangeability itself. This dialectic of spatial fungibility and geographic specificity has intensified rivalries for volatile commodity flows and made logistics‐oriented development a particularly risky growth strategy for cities. What is at stake in these speculative ventures is the welfare of vulnerable communities and workers, who disproportionately bear the costs and risks of supply‐chain volatility

Capital’s logistical fix: Accumulation, globalization, and the survival of capitalism

The growth and transformation of logistics have been attributed to a specific confluence of forces that compelled firms to turn their attention to the circulation of commodities in the second half of the 20th century. This article seeks to develop a more theoretically informed account of the logistics revolution by delineating the industry’s role in promoting the accumulation of capital and the reproduction of capitalism. Drawing on Marxian geographical thought, I contend that the logistical turn of the past five decades has facilitated a multifaceted “spatial fix” to capitalism’s chronic problem of overaccumulation—one that has reconfigured the geographies of circulation as well as production, consumption, and appropriation. This argument has important implications for our understanding of globalization. By enhancing the mobility of both commodity capital and the production process itself, advances in logistics have been an essential, albeit neglected, condition of global economic integration since the 1970s

Silicon sheet surface studies

Several activities were performed in the area of silicon sheet surface studies. An interferometry technique was developed for measuring residual stresses in short, thin silicon sheets. Simulation of abrasion of silicon by diamond and by scrating and indentation tests was carried out. The wear rate in silicon was correlated with a wear model

Finding New Rules for Incomplete Theories: Induction with Explicit Biases in Varying Contexts

Many AI problem solvers possess explicitly encoded knowledge - a domain theory ““ that they use to solve problems. If these problem solvers are to be autonomous, they must be able to detect and to fill gaps in their own knowledge. The field of machine learning addresses this issue. Recently two disparate machine learning approaches have emerged as predominant in the field: explanation-based learning (EBL) and similarity-based learning (SBL), EBL and SBL have been applied to problems in a variety of domains. Both methods have clear problems, however, EBL assumes that a system is given an explicit theory of the domain that is complete, correct, and tractable. These assumptions are clearly unrealistic for most complex, real-world problems. SBL suffers because of its lack of an explicit theory of the domain. The simplicity of the method requires that human intervention playa large role in tailoring input examples and the features describing them in such a way as to allow a system to choose an appropriate set of features to define a concept. Biasing a system in this way may result in its being unable to discover all concepts in even a Single domain. Less tailoring of the examples leaves a system open to the possibility of not converging on the best definition for a concept, or any at all, due to the computational complexity. The research described in this proposal addresses a number of the problems found in explanation-based and similarity-based learning. The major focus of the research is the elimination of the assumption that the domain theory of an EBL system is complete. In particular, it considers the problem of working with an incomplete theory by suggesting a method by which gaps in an EBL system's knowledge can be detected and filled. We suggest that when EBL cannot derive a complete explanation, the partial explanation focus a context in which learning takes place. Information extracted from partial explanations, as well as from complete explanations, can be exploited by SBL to do better induction of the missing domain knowledge. The extracted information constitutes an explicit bias for similarity-based learning. A second problem to be addressed is that of making the biases of SBL explicit. Finally, all testing of the claims made in this proposal is to be done in the Gemini learning system. The development of the system addresses the goal of constructing an integrated learning architecture utilizing both EBL and SBL

Surface property modification of silicon

The main emphasis of this work has been to determine the wear rate of silicon in fluid environments and the parameters that influence wear. Three tests were carried out on single crystal Czochralski silicon wafers: circular and linear multiple-scratch tests in fluids by a pyramidal diamond simulated fixed-particle abrasion; microhardness and three-point bend tests were used to determine the hardness and fracture toughness of abraded silicon and the extent of damage induced by abrasion. The wear rate of (100) and (111) n and p-type single crystal Cz silicon abraded by a pyramidal diamond in ethanol, methanol, acetone and de-ionized water was determined by measuring the cross-sectional areas of grooves of the circular and linear multiple-scratch tests. The wear rate depends on the loads on the diamond and is highest for ethanol and lowest for de-ionized water. The surface morphology of the grooves showed lateral and median cracks as well as a plastically deformed region. The hardness and fracture toughness are critical parameters that influence the wear rate. Microhardness tests were conducted to determine the hardness as influenced by fluids. Median cracks and the damage zone surrounding the indentations were also related to the fluid properties

“WE LET THEM BE OUR EXTENDED FAMILY”: DISENTANGLING STÓ:LÕ FAMILIES FROM THE COLONIAL PAST

This thesis seeks to problematize current historiographic approaches to family, generally, and Indigenous families, specifically. Contrary to much of the scholarship on this topic, Indigenous families like the Stó:lõ have found ways to accommodate changes resulting from colonial interference, allowing them to retain an impressive degree of cultural continuity even as they adapt. The methodology for this study combines ethnohistorical approaches with discourse analysis, placing community-based research and interviews alongside archival documents and historical records to show that families are actively defined and constructed in response to both external and internal change. As this thesis argues, Stó:lõ families are individually and uniquely connected to their cultural traditions in ways that are flexible and innovative, and their responses to change have been facilitated by this flexibility. The first chapter analyses recorded oral histories and myth-age stories of the Stó:lõ to expand understandings of the ways families were defined, maintained, and experienced prior to contact. Chapter two places these perspectives alongside fur trade records, missionary reports, Department of Indian Affairs reports, and documented personal accounts to assert that Stó:lõ families were not simply passive receptors or archives of historical change, but were historical agents actively negotiating this change. The final chapter overlaps historical documents and secondary sources with recent interviews with Stó:lõ community members to show that internal systems to facilitate changes to families remain, but have shifted to become more inclusive—partially in response to colonial restrictions, and partially as a way to expand family networks and the social obligations that accompany families. Although this study draws on examples of Indigenous families, it also points out some of the broader benefits of approaching the family as a set of multiple and dynamic social relationships that contain and exert power within a culturally defined historical continuum. Families provide us with another way of thinking about how local knowledge, tradition, and innovation are defined and applied. While changes did occur within and among Coast Salish families, they were largely filtered through local Indigenous knowledge and expectations. As the example of the Stó:lõ asserts, there is not a singular or normative definition of families. Rather, the expansive approaches to Stó:lõ families are shaped by precedent and culturally normative assumptions, allowing them to remain meaningful as they change over time

Proof of Concept For the Use of Motion Capture Technology In Athletic Pedagogy

Visualization has long been an important method for conveying complex information. Where information transfer using written and spoken means might amount to 200-250 words per minute, visual media can often convey information at many times this rate. This makes visualization a potentially important tool for education. Athletic instruction, particularly, can involve communication about complex human movement that is not easily conveyed with written or spoken descriptions. Video based instruction can be problematic since video data can contain too much information, thereby making it more difficult for a student to absorb what is cognitively necessary. The lesson is to present the learner what is needed and not more. We present a novel use of motion capture animation as an educational tool for teaching athletic movements. The advantage of motion capture is its ability to accurately represent real human motion in a minimalist context which removes extraneous information normally found in video. Motion capture animation only displays motion information, not additional information regarding the motion context. Producing an “automated coach” would be too large and difficult a problem to solve within the scope of a Master's thesis but we can perform initial steps including producing a useful software tool which performs data analysis on two motion datasets. We believe such a tool would be beneficial to a human coach as an analysis tool and the work would provide some useful understanding of next important steps towards perhaps someday producing an automated coach

Surface property modification of semiconductors by fluid absorption

The University of Illinois at Chicago program to develop an understanding of the basic mechanisms of deformation during the lubricated cutting of silicon is discussed. Also described is the development of a nondestructive measurement technique for residual stress in a silicon sheet