NUMERICAL PREDICTION OF SCALE EFFECTS ON THE PROPULSION PERFORMANCE OF JOUBERT BB2 SUBMARINE

The motivation of this study is to present the scale effects on the propulsion performance of Joubert BB2 submarine with MARIN7371R propeller. Joubert BB2 submarine was designed as a realistic attack submarine to be used in benchmarking studies. Numerical analyses were conducted solving RANS equations. The propeller in the self-propelled case was modeled using the body force method. The numerical method was verified both for submarine and open water propeller cases. The resistance, open water propeller and propulsion characteristics were validated with the available numerical/experimental data. After, the results were extrapolated to the full-scale and compared with other studies. Full-scale RANS analyses were then conducted to calculate the resistance and propulsion parameters by eliminating the possible scale effects. The extrapolated full-scale results were compared with the full-scale analyses and self-propulsion method (SPE) results. The scale effects on the resistance and propulsion parameters were obtained in detail. 1978 ITTC prediction method coupled with the body force method was utilized to observe the scale effects. In addition to this, the practicality of the SPE method for the estimation of the propulsive performance was shown. The scale effects on the propulsive parameters such as nominal wake and thrust deduction factors, open water propeller efficiency and propulsion efficiency were seen

Design and Optimization of Broadband High Impedance Ground Planes (HIGP) for Surface Mount Antennas

Gain and bandwidth metrics of broad-band low-profile antennas severely deteriorate when they are placed conformally onto the conductive skins of air, sea, and ground platforms. This detrimental effect is primarily due to out-of-phase reflections from the conductive body interfering with the antenna’s self radiation. Furthermore, lateral waves launched by the antenna couple into the thin substrate placed between the antenna and the platform, giving rise to surface waves resulting in significant diffraction from the edges of the substrate. To remedy these two major mechanisms degrading antenna performance, high impedance ground planes (HIGP) were designed. HIGPs made of a 2-dimensional periodic arrangement of a mushroom structure not only provide perfect-magnetic-conductor (PMC)-like reflection but also suppress the surface waves within the stop-band of the substrate modes. This thesis presents new geometrical shape HIGP-antenna designs and optimizations. Dipole antenna, log periodic antenna and finally bow-tie antennas are used in the research. Operating frequency bands of these antennas over different types of optimized HIGP’s are investigated. Multi-scale HIGP and antenna designs are introduced in the final part of the thesis. Broadband nature of the HIGP-antenna designs is increased by using multi-scale HIGP

College Teaching as Care Work

Sociology and higher education pedagogy scholars argue that college teaching is care work. I analyze reader comments generated by two essays published in the Chronicle of Higher Education and Inside Higher Ed about academic care work and find that many commentators think women should care less. Commenters argued that care work was detrimental to student development and faculty performance. In contrast, I argue that care work promotes learning. What is needed are institutions that make it clear that care work is an expectation for all professors, that provide training to enhance care in the classroom, office, lab, and the field, and that reward professors that excel at using care to help student reach their full potential

Text Selection and Course Design: Faculty Perspectives on Critical Reading and Critical Thinking

This study of sociology faculty in twelve private colleges and universities compares teaching with textbooks and textbook alternatives in undergraduate classes. Faculty explain that textbooks provide a breadth of material that is organized and streamlined in a way that promotes consistency across instructors, facilitates content delivery to students with a range of abilities, and reduces course preparation time. Despite these benefits, faculty have a strong preference for textbook alternatives. Faculty argue that readings, like monographs and journal articles, develop students’ critical reading and thinking skills. Additionally, when instructors design courses with alternative readings they engage their own critical reading and thinking, as they critique and synthesize the literature in their discipline in order to curate texts for the syllabus. We argue that teaching courses with alternative readings creates course experiences where students and faculty engage with a discipline togethe

Error Control of Iterative Linear Solvers for Integrated Groundwater Models

An open problem that arises when using modern iterative linear solvers, such as the preconditioned conjugate gradient (PCG) method or Generalized Minimum RESidual method (GMRES) is how to choose the residual tolerance in the linear solver to be consistent with the tolerance on the solution error. This problem is especially acute for integrated groundwater models which are implicitly coupled to another model, such as surface water models, and resolve both multiple scales of flow and temporal interaction terms, giving rise to linear systems with variable scaling. This article uses the theory of 'forward error bound estimation' to show how rescaling the linear system affects the correspondence between the residual error in the preconditioned linear system and the solution error. Using examples of linear systems from models developed using the USGS GSFLOW package and the California State Department of Water Resources' Integrated Water Flow Model (IWFM), we observe that this error bound guides the choice of a practical measure for controlling the error in rescaled linear systems. It is found that forward error can be controlled in preconditioned GMRES by rescaling the linear system and normalizing the stopping tolerance. We implemented a preconditioned GMRES algorithm and benchmarked it against the Successive-Over-Relaxation (SOR) method. Improved error control reduces redundant iterations in the GMRES algorithm and results in overall simulation speedups as large as 7.7x. This research is expected to broadly impact groundwater modelers through the demonstration of a practical approach for setting the residual tolerance in line with the solution error tolerance.Comment: 13 pages and 1 figur

Social Determinants in Latino Diet and Health

This study problematizes generalized patterns in Latino diet and health after reviewing obesity and food consumption patterns by race and ethnicity gleaned from the social science and health science literature comparing Mexican-origin American, European-origin American, and African-American food consumption patterns, and summarizes data from the 2009/2010 National Health and Nutrition Examination Survey (NHANES). The data from these surveys describes the quantity of fruit, vegetables, grains, meat, and other foods consumed. We review the literature on social determinants of diet to study whether food environments, socioeconomic status, culture, nativity, and globalization shape dietary practices

EFFECTS OF TEST PARAMETERS ON THE PRODUCTION OF HEXAGONAL BORON NITRIDE BY DCRN METHOD

conference paper at FunGlass School - part

STRONG POROUS GLASS-CERAMICS FROM ALKALI ACTIVATION AND SINTER-CRYSTALLIZATION OF VITRIFIED MSWI BOTTOM ASH

Vitrification of municipal solid waste incineration (MSWI) bottom ash is an effective method to produce a chemically stable glass, with metal recovery. In order to justify the high costs of this process, the vitrified residue can then be upcycled into potential marketable products. In this study, vitrified bottom ash was successfully converted into strong and chemically stable porous glass-ceramics by the combination of alkali activation and sintering. After the activation of the glass in a NaOH solution of low molarity, foams were easily produced by intensive mechanical stirring, with the aid of a surfactant, and stabilized by gelation. The obtained open-celled material was further consolidated by a sintering treatment, at 800-900\ub0C. The addition of recycled soda-lime glass allowed activation at low molarity and sintering at lower temperature, but it reduced the mechanical properties and the stabilization of heavy metals. On the other hand, the increase in molarity of the alkaline solution increased the porosity and also the strength of foams from vitrified bottom ash