12,681 research outputs found
Holistic finite differences accurately model the dynamics of the Kuramoto-Sivashinsky equation
We analyse the nonlinear Kuramoto-Sivashinsky equation to develop an accurate
finite difference approximation to its dynamics. The analysis is based upon
centre manifold theory so we are assured that the finite difference model
accurately models the dynamics and may be constructed systematically. The
theory is applied after dividing the physical domain into small elements by
introducing insulating internal boundaries which are later removed. The
Kuramoto-Sivashinsky equation is used as an example to show how holistic finite
differences may be applied to fourth order, nonlinear, spatio-temporal
dynamical systems. This novel centre manifold approach is holistic in the sense
that it treats the dynamical equations as a whole, not just as the sum of
separate terms
Radioactive isotope analyses of skeletal materials in forensic science: a review of uses and potential uses
A review of information that can be provided from measurements made on natural and anthropogenic radionuclide activities in human skeletal remains has been undertaken to establish what reliable information of forensic anthropological use can be obtained regarding years of birth and death (and hence post-mortem interval (PMI)). Of the anthropogenic radionuclides that have entered the environment, radiocarbon (14C) can currently be used to generate the most useful and reliable information. Measurements on single bones can indicate whether or not the person died during the nuclear era, while recent research suggests that measurements on trabecular bone may, depending on the chronological age of the remains, provide estimates of year of death and hence PMI. Additionally, 14C measurements made on different components of single teeth or on teeth formed at different times can provide estimates of year of birth to within 1–2 years of the true year. Of the other anthropogenic radionuclides, 90Sr shows some promise but there are problems of (1) variations in activities between individuals, (2) relatively large analytical uncertainties and (3) diagenetic contamination. With respect to natural series radionuclides, it is concluded that there is no convincing evidence that 210Pb dating can be used in a rigorous, quantitative fashion to establish a PMI. Similarly, for daughter/parent pairs such as 210Po/210Pb (from the 238U decay series) and 228Th/228Ra (from the 232Th decay series), the combination of analytical uncertainty and uncertainty in activity ratios at the point of death inevitably results in major uncertainty in any estimate of PMI. However, observation of the disequilibrium between these two daughter/parent pairs could potentially be used in a qualitative way to support other forensic evidence
Rangia and Marsh Clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, in Eastern México: Distribution, Biology and Ecology, and Historical Fisheries
Rangia and marsh clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, occur in brackish waters along México’s eastern coast from the northern State of Tamaulipas
to the southern State of Campeche. The clams were important to the prehispanic people in the southern part of the State of Veracruz, where they were used as food and as construction material. In modern times, they are harvested for food. The fishermen wade in shallow water and harvest the clams in soft sediments by hand. Annual landings of whole clams during a recent 5-yr period, 1998–2002, were 1,139–1,695 t. The only area with a substantial ongoing clam fishery is in the Lower Papaloapan River Basin, including Alvarado Lagoon, where as many as 450 fishermen are licensed harvesters. This fishery for the Rangia and marsh clams is the most important clam fishery along
México’s Gulf Coast
Elastic stress concentration at radial crossholes in pressurised thick cylinders
Results of a parametric finite element analysis investigation of stress concentration at radial crossholes in pressurized cylinders are presented in numerical and graphical form. The analysis shows that the location of maximum stress does not generally occur at the junction between the bores, as is commonly supposed, but at some small distance up the crosshole from the junction. Maximum stress concentration factors (SCFs) are defined on the basis of the maximum principal stress, von Mises equivalent stress, and stress intensity. Three-dimensional plots of the SCF against the cylinder radius ratio b/a and the crosshole-to-main-bore-radius ratio c/a are presented. The SCFs were found to vary across the range of geometries considered with local minima identified within the parameter range in most cases. The results therefore allow designers to select optimum b/a and c/a ratios to minimize stress concentration in real problems
The Oyster Industry of Eastern Mexico
Mexico has an oyster industry of substantial size, ranking about sixth in the world. In 1993, among the top ten oyster producers, Korea, Japan, the United States, China, and France ranked ahead of Mexico, while the Philippines, Australia, Canada, and New Zealand trailed it (Fig. 1). On its east coast, the species landed is the eastern oyster, Crassostrea virginica, while on its west coast C. corteziensis, C. iridescens, and the Pacific oyster, C. gigas, are landed. During the last 10-15 years, annual production often was at least 50,000 t of shelled oysters, or nearly 1.5 million bushels (Anonymous, 1995), with the great preponderance (90%) coming from a series of lagoons connecting with the Gulf of Mexico along the east coast (Fig. 2) and the remainder produced on the west coast
Accurately model the Kuramoto--Sivashinsky dynamics with holistic discretisation
We analyse the nonlinear Kuramoto--Sivashinsky equation to develop accurate
discretisations modeling its dynamics on coarse grids. The analysis is based
upon centre manifold theory so we are assured that the discretisation
accurately models the dynamics and may be constructed systematically. The
theory is applied after dividing the physical domain into small elements by
introducing isolating internal boundaries which are later removed.
Comprehensive numerical solutions and simulations show that the holistic
discretisations excellently reproduce the steady states and the dynamics of the
Kuramoto--Sivashinsky equation. The Kuramoto--Sivashinsky equation is used as
an example to show how holistic discretisation may be successfully applied to
fourth order, nonlinear, spatio-temporal dynamical systems. This novel centre
manifold approach is holistic in the sense that it treats the dynamical
equations as a whole, not just as the sum of separate terms.Comment: Without figures. See
http://www.sci.usq.edu.au/staff/aroberts/ksdoc.pdf to download a version with
the figure
The Legal Framework for States as Employers-of-Choice in Workplace Flexibility: A Case Study of Arizona and Michigan
Outlines the statutes, regulations, executive actions, and collective bargaining agreements that authorize flexible work arrangements, time off, and career flexibility in the two state workforces; the elements of model programs; and their benefits
Chester Union Free School District and Chester Teachers\u27 Association Chester Union Free School District and Chester Teachers\u27 Association
In the Matter of the Fact-finding - between - THE CHESTER UNION FREE SCHOOL DISTRICT and THE CHESTER TEACHERS’ ASSOCIATION. Case No. M 2006-114. Susan T. Mackenzie, Fact-finde
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