Over the last decades, integrated circuits have changed our everyday lives in a number of ways. Many common devices today taken for granted would not have been possible without this industrial revolution. Central to the manufacturing of integrated circuits is the photomask used to expose the wafers. Additionally, such photomasks are also used for manufacturing of flat screen displays. Microlithography, the manufacturing technique of such photomasks, requires complex electronics equipment that excels in both speed and fidelity. Manufacture of such equipment requires competence in virtually all engineering disciplines, where the conversion of geometry into pixels is but one of these. Nevertheless, this single step in the photomask drawing process has a major impact on the throughput and quality of a photomask writer. Current high-end semiconductor writers from Micronic use a cluster of Field-Programmable Gate Array circuits (FPGA). FPGAs have for many years been able to replace Application Specific Integrated Circuits due to their flexibility and low initial development cost. For parallel computation, an FPGA can achieve throughput not possible with microprocessors alone. Nevertheless, high-performance FPGAs are expensive devices, and upgrading from one generation to the next often requires a major redesign. During the last decade, the computer games industry has taken the lead in parallel computation with graphics card for 3D gaming. While essentially being designed to render 3D polygons and lacking the flexibility of an FPGA, graphics cards have nevertheless started to rival FPGAs as the main workhorse of many parallel computing applications. This thesis covers an investigation on utilizing graphics cards for the task of rendering geometry into photomask patterns. It describes different strategies that were tried and the throughput and fidelity achieved with them, along with the problems encountered. It also describes the development of a suitable evaluation framework that was critical to the process.

<p>Over the last decades, integrated circuits have changed our everyday lives in a number of ways. Many common devices today taken for granted would not have been possible without this industrial revolution.</p><p>Central to the manufacturing of integrated circuits is the photomask used to expose the wafers. Additionally, such photomasks are also used for manufacturing of flat screen displays. Microlithography, the manufacturing technique of such photomasks, requires complex electronics equipment that excels in both speed and fidelity. Manufacture of such equipment requires competence in virtually all engineering disciplines, where the conversion of geometry into pixels is but one of these. Nevertheless, this single step in the photomask drawing process has a major impact on the throughput and quality of a photomask writer.</p><p>Current high-end semiconductor writers from Micronic use a cluster of Field-Programmable Gate Array circuits (FPGA). FPGAs have for many years been able to replace Application Specific Integrated Circuits due to their flexibility and low initial development cost. For parallel computation, an FPGA can achieve throughput not possible with microprocessors alone. Nevertheless, high-performance FPGAs are expensive devices, and upgrading from one generation to the next often requires a major redesign.</p><p>During the last decade, the computer games industry has taken the lead in parallel computation with graphics card for 3D gaming. While essentially being designed to render 3D polygons and lacking the flexibility of an FPGA, graphics cards have nevertheless started to rival FPGAs as the main workhorse of many parallel computing applications.</p><p>This thesis covers an investigation on utilizing graphics cards for the task of rendering geometry into photomask patterns. It describes different strategies that were tried and the throughput and fidelity achieved with them, along with the problems encountered. It also describes the development of a suitable evaluation framework that was critical to the process.</p>

The purposes of this research were to determine the efficacy of using the Ogawa® passive sampling device (PSD) to measure ammonia and to identify significant ammonia sources adjacent to Hillsborough and Tampa Bay. Ninety-four samplers were deployed over a 180-km2 area for two weeks in October 2001. Within the area sampled were located suburbs, an urban center, major highways, port activities, fertilizer manufacturing, wastewater treatment, coal-combustion power plants, warehousing and dairy farming. The sampled locations were arranged in a triangular grid pattern spaced 1.5 km apart. The pattern was designed to locate circular hot spots with a minimum radius of 0.75 km. The minimum, maximum, mean, and median ammonia concentrations were 0.06, 15, 2.0, and 1.5 mg/m3, respectively, and the estimated precision was 16%. Hot spots identified from kriged concentration data coincided with inventoried ammonia sources. The relative bias and precision of the PSD based on collocation with an annular denuder system were (plus or minus) 30 % and 20 %.

Thesis (M.Sc. (Statistics)) -- University of Limpopo, 2019 / This research study has demonstrated the complexity involved in complex survey sample design (CSSD). Furthermore the study has proposed methods to account for each step taken in sampling and at the estimation stage using the theory of survey sampling, CSSD-based case studies and practical implementation based on census attributes. CSSD methods are designed to improve statistical efficiency, reduce costs and improve precision for sub-group analyses relative to simple random sample(SRS).They are commonly used by statistical agencies as well as development and aid organisations. CSSDs provide one of the most challenging fields for applying a statistical methodology. Researchers encounter a vast diversity of unique practical problems in the course of studying populations. These include, interalia: non-sampling errors,specific population structures,contaminated distributions of study variables,non-satisfactory sample sizes, incorporation of the auxiliary information available on many levels, simultaneous estimation of characteristics in various sub-populations, integration of data from many waves or phases of the survey and incompletely specified sampling procedures accompanying published data. While the study has not exhausted all the available real-life scenarios, it has outlined potential problems illustrated using examples and suggested appropriate approaches at each stage. Dealing with the attributes of CSSDs mentioned above brings about the need for formulating sophisticated statistical procedures dedicated to specific conditions of a sample survey. CSSD methodologies give birth to a wide variety of approaches, methodologies and procedures of borrowing the strength from virtually all branches of statistics. The application of various statistical methods from sample design to weighting and estimation ensures that the optimal estimates of a population and various domains are obtained from the sample data.CSSDs are probability sampling methodologies from which inferences are drawn about the population. The methods used in the process of producing estimates include adjustment for unequal probability of selection (resulting from stratification, clustering and probability proportional to size (PPS), non-response adjustments and benchmarking to auxiliary totals. When estimates of survey totals, means and proportions are computed using various methods, results do not differ. The latter applies when estimates are calculated for planned domains that are taken into account in sample design and benchmarking. In contrast, when the measures of precision such as standard errors and coefficient of variation are produced, they yield different results depending on the extent to which the design information is incorporated during estimation. The literature has revealed that most statistical computer packages assume SRS design in estimating variances. The replication method was used to calculate measures of precision which take into account all the sampling parameters and weighting adjustments computed in the CSSD process. The creation of replicate weights and estimation of variances were done using WesVar, astatistical computer package capable of producing statistical inference from data collected through CSSD methods. Keywords: Complex sampling, Survey design, Probability sampling, Probability proportional to size, Stratification, Area sampling, Cluster sampling.

Document formatted into pages; contains 115 pages. / Title from PDF of title page. / Original thesis was submitted in HTML and can be accessed at http://www.lib.usf.edu/EDT-db/theses/available/etd-10262001-162331/unrestricted/default.htm / Thesis (M.S.)--University of South Florida, 2002. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The purposes of this research were to determine the efficacy of using the Ogawa]a passive sampling device (PSD) to measure ammonia and to identify significant ammonia sources adjacent to Hillsborough and Tampa Bay. Ninety-four samplers were deployed over a 180-km2 area for two weeks in October 2001. Within the area sampled were located suburbs, an urban center, major highways, port activities, fertilizer manufacturing, wastewater treatment, coal-combustion power plants, warehousing and dairy farming. The sampled locations were arranged in a triangular grid pattern spaced 1.5 km apart. The pattern was designed to locate circular hot spots with a minimum radius of 0.75 km. The minimum, maximum, mean, and median ammonia concentrations were 0.06, 15, 2.0, and 1.5 mg/m3, respectively, and the estimated precision was 16%. Hot spots identified from kriged concentration data coincided with inventoried ammonia sources. / ABSTRACT: The relative bias and precision of the PSD based on collocation with an annular denuder system were (plus or minus) 30 % and 20 %. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.