Error detection and control for nonlinear shell analysis

A problem-adaptive solution procedure for improving the reliability of finite element solutions to geometrically nonlinear shell-type problem is presented. The strategy incorporates automatic error detection and control and includes an iterative procedure which utilizes the solution at the same load step on a more refined model. Representative nonlinear shell problem are solved

A study of adult 'non-singers' in Newfoundland

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Computational methods for global/local analysis

Computational methods for global/local analysis of structures which include both uncoupled and coupled methods are described. In addition, global/local analysis methodology for automatic refinement of incompatible global and local finite element models is developed. Representative structural analysis problems are presented to demonstrate the global/local analysis methods

Large-scale structural analysis: The structural analyst, the CSM Testbed and the NAS System

The Computational Structural Mechanics (CSM) activity is developing advanced structural analysis and computational methods that exploit high-performance computers. Methods are developed in the framework of the CSM testbed software system and applied to representative complex structural analysis problems from the aerospace industry. An overview of the CSM testbed methods development environment is presented and some numerical methods developed on a CRAY-2 are described. Selected application studies performed on the NAS CRAY-2 are also summarized

Population growth rate of a common understory herb decreases non-linearly across a gradient of deer herbivory

Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Forest Ecology and Management 257 (2009): 1095-1103, doi:10.1016/j.foreco.2008.11.018.Overabundant white-tailed deer (Odocoileus virginianus) are a significant management problem in North America that exert unprecedented herbivory pressure on native understory forest communities. Conserving understory plant populations requires quantifying a sustainable level of deer herbivory. To date, most population projection models consider only deer presence and absence. To estimate population growth rate along a gradient of herbivory, we focused on Trillium grandiflorum because it is a common understory species and a bellwether of deer effects and forest decline. We used matrix population models, and employed both prospective and retrospective analyses using a regression life table response experiment (LTRE). Deer affect size, stage and population dynamics of T. grandiflorum. Because deer target flowering and large non-flowering stages of T. grandiflorum, these individuals do not produce seed in the year they are browsed and are more likely to regress in stage and size in the following growing season relative to non-browsed plants. Importantly, sustained high browse levels result in populations dominated by small, non-flowering individuals. Our LTRE revealed a significant negative and decelerating relationship between herbivory and λ. This non-linearity occurs at the highest herbivory levels because highly browsed populations become dominated by stages that deer do not consume and are thus buffered from rapid decline. However, population extinction is expected when herbivory is greater than the pivotal value of ~15%. Our study demonstrates that levels of deer herbivory commonly experienced by forest understory perennials are sufficient to cause the loss of T. grandiflorum and likely other co-occurring palatable species.We thank the National Science Foundation (DEB-0105000 and DEB-0108208 to SK), McKinley and Darbarker Research Funds and Botany in Action (Phipps Conservatory and Botanical Garden) for funding

A Racial Impact Analysis of HB 869/SB 274

Virginia is growing. Between 1990 and 2000, Virginia’s population rose by over 14% - the largest population growth experienced by the state in a single decade (Pollard, 2007). And the state continues to grow. It has been estimated that by 2030, Virginia’s total population may exceed 9.8 million people (Pollard, 2007). Along with population growth, land development has increased which in turn affects transportation, housing and job placement across the Commonwealth. In fact, in many parts of the state, development has outpaced population growth. According to Pollard, “If current patterns continue, Virginia will develop more land in the next 40 years than in the previous 400 years (p.8).” In an effort to curb sprawling development and decrease transportation expenditure, the Virginia General Assembly passed House Bill 3202 in 2007. One major outcome of this multifaceted legislation was the introduction of mandatory Urban Development Areas (UDAs). The goal of UDAs was for localities to concentrate growth and development in order to reduce the cost of transportation and increase opportunities to build multi-use developments and expand affordable housing. In 2012, the General Assembly passed House Bill 869 and Senate Bill 274 which effectively make UDAs no longer mandatory but optional for all localities in the Commonwealth. In this paper, we analyze the racial impact and explore the political history of HB 869/SB 274 while addressing the larger issue of sprawl across the Commonwealth. Smart Growth policies are known to positively impact the environment but they also positively impact low-income and minority communities by increasing access to housing, transportation and ultimately jobs. The story behind Urban Development Areas in the Commonwealth is one of politics and regulation but issues as critical as housing, transportation and job access should be focused much more on the citizens of the Commonwealth. The friction created by the UDA policy between the localities and the state has the potential to spark a statewide conversation about land use and more importantly - the need for people-centered solutions to a growing problem

Infectious etiologies of acute otitis media

There is no preferred method for establishing the infectious etiology of acute otitis media (AOM). Bacterial or viral pathogens are found in most cases. Bacterial pathogens are more common than viruses in middle ear fluid samples collected from children with AOM and intact tympanic membranes. Studies using newer detection methods reveal more viral pathogens than those using less sensitive methods