Enriched and Isogeometric Boundary Element Methods for Acoustic Wave Scattering

This thesis concerns numerical acoustic wave scattering analysis. Such problems have been solved with computational procedures for decades, with the boundary element method being established as a popular choice of approach. However, such problems become more computationally expensive as the wavelength of an incident wave decreases; this is because capturing the oscillatory nature of the incident wave and its scattered field requires increasing numbers of nodal variables. Authors from mathematical and engineering backgrounds have attempted to overcome this problem using a wide variety of procedures. One such approach, and the approach which is further developed in this thesis, is to include the fundamental character of wave propagation in the element formulation. This concept, known as the Partition of Unity Boundary Element Method (PU-BEM), has been shown to significantly reduce the computational burden of wave scattering problems. This thesis furthers this work by considering the different interpolation functions that are used in boundary elements. Initially, shape functions based on trigonomet- ric functions are developed to increase continuity between elements. Following that, non-uniform rational B-splines, ubiquitous in Computer Aided Design (CAD) soft- ware, are used in developing an isogeometric approach to wave scattering analysis of medium-wave problems. The enriched isogeometric approach is named the eXtended Isogeometric Boundary Element Method (XIBEM). In addition to the work above, a novel algorithm for finding a uniform placement of points on a unit sphere is presented. The algorithm allows an arbitrary number of points to be chosen; it also allows a fixed point or a bias towards a fixed point to be used. This algorithm is used for the three-dimensional acoustic analyses in this thesis. The new techniques developed within this thesis significantly reduce the number of degrees of freedom required to solve a problem to a certain accuracy—this reduc- tion is more than 70% in some cases. This reduces the number of equations that have to be solved and reduces the amount of integration required to evaluate these equations

Modeling Plant Uptake of Metal in Constructed Wetlands Supported by Experimentally Derived Uptake Rates

Many communities and Air Force installations are using constructed wetlands to filter trace metals from their stormwater runoff. Constructed wetlands are attractive to industry for runoff mitigation because they are relatively cheap to build and operate and require little or no energy for operation. The purpose of this research project is to develop quantitative concepts for understanding the dynamics of metal uptake in constructed wetland plants by constructing a system dynamics model supported by experimental observation and offer environmental managers a tool to simulate, under a broad range of conditions, long term wetland exposure to stormwater runoff contaminated with trace metals. There are two phases in this project, a modeling phase and an experimental phase. Greater emphasis was given to model development initially in order to determine aspects of the experimental design. The results of the study indicate that metal can accumulate in wetland plants and sediment. Changes in different wetland parameters affect the rate at which metal accumulates in wetland plants and other components. A complete understanding of which wetland parameters to manipulate is essential for proper management of constructed wetlands for stormwater treatment

Made in China?: Analyzing the Decline in Offshoring to the PRC

This paper will primarily discuss globalization, primarily around the movement of manufacturing in and out of the People’s Republic of China (PRC). This thesis analyzes both qualitative and quantitative data in order to estimate the true motivators for moving manufacturing to China (i.e., offshoring), and reasons why not to move manufacturing to China, or even reasons to move manufacturing back from China (i.e., reshoring). This thesis also considers potential alternative options for countries in the case that a company may be looking to outsource manufacturing but may still want some of the advantages of offshoring their manufacturing. This thesis thus argues that the decision to offshore manufacturing goods to China was made only considering potential short term gains in cost-cutting due to less expensive Chinese labor and resources and the speed at which Chinese manufacturing could begin, but did not consider long-term disadvantages of basing manufacturing in a very distant place, relying on a handful of incredibly busy ports, and relying on manufacturing from a country in a diplomatically difficult position with the United States of America. Instead, a more holistic approach to global supply chain management should be embraced that more seriously considers not only short-term but also long-term advantages and disadvantages to offshoring production to any country, the PRC in particular

Academic Perspectives on Agribusiness: An International Survey

The IFAMR is published by (IFAMA) the International Food and Agribusiness Management Review. www.ifama.orgpromotion and tenure, agribusiness, teaching, grantsmanship, research, Agribusiness, Institutional and Behavioral Economics, Productivity Analysis, Teaching/Communication/Extension/Profession, Q130,

Radio Controlled Aircraft

Building an R/C aircraft isn’t exactly a project intent on breaking ground in the field of aerospace engineering, rather it is an opportunity to apply fluid dynamics in a practical manner to gain experience in aeronautical engineering. An aerospace engineer is one who designs and builds aircraft and spacecraft and are often tasked with deeming an aircraft flight worthy or not. We will attempt to predict the feasibility of our custom plane designs using aircraft engineering techniques found through research and through texts provided by our advisor, Dr. Jayasimha. The goal of this design is to design and fabricate a plane that abides by the SAE 2012 Aircraft Competition guidelines. These constraints require the plane to lift off in under 200 ft of runway, not have rotary wings (such as helicopter), weigh less than 55 lbs, and the propeller must rotate at the same RPM as the motor. The problem we are trying to solve is to accurately predict the behavior of the model prior to fabrication by using aerodynamic engineering calculations and simplifications. We aim to predict the take-off velocity, the induced drags on the plane, required engine performance, in-flight performance, and overall feasibility of the design. If successful, we will gain a decent understanding of how aerospace engineers predict the flight behavior and specification requirements of airplanes. It is actually more difficult to design a flightworthy small-scale aircraft rather than a large commercial one due to the low altitude of operation, which induces fairly laminar boundary conditions, which in turn increases the drag force on the plane. In order to do this, coefficients of lift and drag of the airplane’s airfoil will be found using the software XFLYER 5, which is a specialized program for aircraft design. Using this software and formulae found from R/C aircraft related texts, an excel sheet will be made to predict flight performance and by altering the dimensions of the plane and airfoil shape, we will be able to choose the most flightworthy design. So far we are working with an airfoil at an angle of attack of 7 degrees which yields a coefficient of lift of 0.943 and a coefficient of drag of 0.0062. With rectangular wings 13’’X 42’’, a fuselage of length 5.5 ft, a Rimfire 1.60 motor, and a weight of 25 lbs, it was predicted that the plane will need to reach 37mph, overcome a drag of 14.5 Newtons, and will take about 77 ft of runway to lift off. We aim to reduce these values by adjusting parameters accordingly.https://scholarscompass.vcu.edu/capstone/1053/thumbnail.jp

γδ T cell response to prolonged heavy endurance exercise

The focus of this study was to assess exercise-induced alterations in circulating γδ T cell subpopulations and memory phenotypes after a prolonged heavy-intensity exercise bout. Ten highly-trained endurance cyclists (mean ± SEM: age 24.0 ± 1.3 years; height 1.81 ± 0.02 m; body mass 73.3 ± 1.8 kg; peak oxygen uptake 60.7 ± 1.5 mL.kg-1.min-1) performed 2 h of cycling exercise at 90% of the second ventilatory threshold. Blood samples were collected before exercise, immediately post-exercise, 1 h, 2 h, 4 h, and 6 h post-exercise. Flow cytometry was used to examine γδ T cell subsets, memory phenotypes and receptor expression. A significant decrease in cell concentration was observed in total γδ T cells and the δ2 subset from pre-exercise to 1 h, 2 h, and 4 h post-exercise. Further analysis of the δ2 subset revealed a significant decrease from pre-exercise to 1 h, 2 h, and 4 h post-exercise in naive δ2 cells, and a significant decrease from pre-exercise to 1 h and 2 h post-exercise in central memory δ2 cells. A significant decrease was observed in γδ T cells expressing CD11ahigh, CD62Lhigh and CD94+ from pre-exercise to 1 h, 2 h, and 4 h post-exercise. Furthermore, a significant decrease was observed from pre-exercise to 1 h post-exercise in CD62Llow and CD94- γδ T cells. These results suggest an exercise-stress-induced redistribution of γδ T cells from the circulation with greater propensity for antigen stimulation, tissue and lymph node homing potential for a duration of 4 h after the cessation of exercise

Inequalities in non-small cell lung cancer treatment and mortality.

BACKGROUND: Non-small cell lung cancer (NSCLC) comprises approximately 85% of all lung cancer cases, and surgery is the preferred treatment for patients. The National Health Service established Primary Care Trusts (PCTs) in 2002 to manage local health needs. We investigate whether PCTs with a lower uptake of surgical treatment are those with above-average mortality 1 year after diagnosis. The applied methods can be used to monitor the performance of any administrative bodies responsible for the management of patients with cancer. METHODS: All adults diagnosed with NSCLC lung cancer during 1998-2006 in England were identified. We fitted mixed effect logistic models to predict surgical treatment within 6 months after diagnosis, and mortality within 1 year of diagnosis. RESULTS: Around 10% of the NCSLC patients received curative surgery. Older deprived patients and those who did not receive surgery had much higher odds of death 1 year after being diagnosed with cancer. In total, 69% of the PCTs were below the lower control limit of surgery and have predicted random intercepts above the mean value of zero of the random effect for mortality, whereas 40% were above the upper control limit of mortality within 1 year. CONCLUSIONS: Our main results suggest the presence of clear geographical variation in the use of surgical treatment of NSCLC and mortality. Mixed-effects models combined with the funnel plot approach were useful for assessing the performance of PCTs that were above average in mortality and below average in surgery

The Effects of Increased Provision of Thoracic Surgical Specialists on the Variation in Lung Cancer Resection Rate in England

Introduction:There is a wide variation in the lung cancer resection rate in England. We assessed the effect of the regional provision of thoracic surgery service on the variation in lung cancer resection rate.Methods:A retrospective observational study correlating National Lung Cancer Audit data with thoracic surgery workforce data was performed to review the lung cancer resection rate in England in 2008 and 2009.Results:In 2008, there was a sixfold variation in resection rate, with a higher resection rate in hospitals where surgeons were based (base hospitals) than in peripheral hospitals (20.0% versus 11.6%, p < 0.001). The resection rate was also higher in cancer networks, which were served by two or more specialist thoracic surgeons (14.6% versus 12.7%, p = 0.028), and where surgeons were present in more than two-thirds of the lung cancer multidisciplinary team meetings (14.4% versus 12.0%, p = 0.046). In 2009, the overall resection rate increased from 14.5% to 18.4%. Four units increased their number of specialist thoracic surgeons and had a significantly higher increase in resection rate than units without expansion (relative rise 66.3% versus 19.2%; p = 0.022).Conclusions:The large variation in the resection rate seems, in part, to be related to the local availability of specialist thoracic surgeons. The greatest improvement in the resection rate was in units with expansion of specialist thoracic surgeons. We suggest the expansion of specialist thoracic surgeons will improve the resection rate and thereby the overall survival of lung cancer in England. This has significant implications for the future of training in cardiothoracic surgery and organization of cancer services

Resonantly enhanced second-harmonic generation using III-V semiconductor all-dielectric metasurfaces

Nonlinear optical phenomena in nanostructured materials have been challenging our perceptions of nonlinear optical processes that have been explored since the invention of lasers. For example, the ability to control optical field confinement, enhancement, and scattering almost independently, allows nonlinear frequency conversion efficiencies to be enhanced by many orders of magnitude compared to bulk materials. Also, the subwavelength length scale renders phase matching issues irrelevant. Compared with plasmonic nanostructures, dielectric resonator metamaterials show great promise for enhanced nonlinear optical processes due to their larger mode volumes. Here, we present, for the first time, resonantly enhanced second-harmonic generation (SHG) using Gallium Arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical resonators we observe SHG enhancement factors as large as 104 relative to unpatterned GaAs. At the magnetic dipole resonance we measure an absolute nonlinear conversion efficiency of ~2X10^(-5) with ~3.4 GW/cm2 pump intensity. The polarization properties of the SHG reveal that both bulk and surface nonlinearities play important roles in the observed nonlinear process

Get What You Give? An Examination of Enlightened Self-Interest, Philanthropic Intent, and Engagement in Philanthropy for Small Firm Owners

Prior researchers agree that small businesses are important community contributors due to their active engagement in broader social responsibility activities, such as philanthropy. Despite their purported importance to charitable giving and philanthropy, little is known about the factors that motivate small business owners’ decisions to engage in philanthropic giving. We integrate enlightened self-interest theory and the theory of planned behavior to examine how enlightened self-interest influences intentions to engage in philanthropy during start-up, which in turn impacts current levels of engagement in philanthropic activities. Our results suggest that intentions to engage in philanthropy at start-up do partially mediate the relationship between enlightened self-interest and engagement in philanthropy behaviors; thus, suggesting that entrepreneurs’ motivations grounded in enlightened self-interest influence intentions to engage in philanthropy and subsequent engagement in such activities