Uniformly high order accurate essentially non-oscillatory schemes 3

In this paper (a third in a series) the construction and the analysis of essentially non-oscillatory shock capturing methods for the approximation of hyperbolic conservation laws are presented. Also presented is a hierarchy of high order accurate schemes which generalizes Godunov's scheme and its second order accurate MUSCL extension to arbitrary order of accuracy. The design involves an essentially non-oscillatory piecewise polynomial reconstruction of the solution from its cell averages, time evolution through an approximate solution of the resulting initial value problem, and averaging of this approximate solution over each cell. The reconstruction algorithm is derived from a new interpolation technique that when applied to piecewise smooth data gives high-order accuracy whenever the function is smooth but avoids a Gibbs phenomenon at discontinuities. Unlike standard finite difference methods this procedure uses an adaptive stencil of grid points and consequently the resulting schemes are highly nonlinear

Analysis of Automotive Cyber-Attacks on Highways using Partial Differential Equation Models

This is the author accepted manuscript.This paper considers scenarios wherein a group of malicious vehicles on a highway perform a cooperative attack with the motive of creating undesirable wave effects among other vehicles on the highway. The two species of vehicles - malicious vehicles and normal vehicles, and their associated interaction effects, are modeled using Partial Differential Equations (PDEs). The malicious vehicles, which may be arbitrarily distributed on the highway, perform a sequence of velocity changes with the objective of making the density/velocity profile on the highway, track a reference profile. This reference profile (chosen by the malicious vehicles) has the property that once generated, it spontaneously evolves into a shock wave that propagates along the highway. Analytical expressions governing the velocity inputs of the malicious vehicles with which they can generate such waves are determined, for perfect as well as imperfect information scenarios. Simulation results are presented to validate the theoryThe first two authors would like to acknowledge support from the National Science Foundation. This material is based upon work supported by the National Science Foundation under Grant IIS-1351677

The Impact of Urbanisation on New Zealand Freshwater Quality

Urban waterways represent less than 1% of the total river length in New Zealand. However, they are the most visible of all rivers, as 86% of New Zealanders live in urban areas. Urban waterways are impaired due to elevated levels of pathogens, turbidity, nutrients and heavy metals originating from anthropogenic activities. In addition to being conduits of storm water run-off from urban areas, some urban waterways also receive discharges from wastewater treatment plants and combined sewage overflows, thus greatly reducing their capacity to provide ecosystem services such as recreation, tourism, biodiversity and mahinga kai. This article summarises the state of New Zealand’s urban freshwater quality, the major drivers of pollution, and mitigation measures needed to restore urban waterways

METHOD DEVELOPMENT AND VALIDATION OF ULTRAVIOLET-VISIBLE SPECTROSCOPIC METHOD FOR THE ESTIMATION OF HEPATITIS-C DRUGS - DACLATASVIR AND SOFOSBUVIR IN ACTIVE PHARMACEUTICAL INGREDIENT FORM

ABSTRACTObjective: The objective of the present work is to develop a simple, efficient, and reproducible spectrophotometric method for the quantitativeestimation of hepatitis-C drugs - Daclatasvir and Sofosbuvir in its active pharmaceutical ingredient (API) form.Methods: The developed ultraviolet spectrophotometric method for the quantitative estimation of hepatitis-C drugs - Daclatasvir and Sofosbuvir isbased on measurement of absorption at a wavelength maximum (λmax) of 317 and 261 nm using methanol as solvent.Results: The method was validated in terms of specificity, precision, linearity, accuracy, and robustness as per the ICH guidelines. The method wasfound to be linear in the range of 50-150% for Daclatasvir and in the range of 43-143% for Sofosbuvir. The percentage recovery values were in therange of 99.4-100.6% for Daclatasvir and in the range of 99.7-100.6% for Sofosbuvir at different concentration levels. Relative standard deviation forprecision and intermediate precision results were found to be <2%. The correlation coefficient value observed for Daclatasvir and Sofosbuvir drugsubstances was not <0.99, 0.99, respectively. Results obtained from the validation experiments prove that the developed method is quantified for theestimation of Daclatasvir and Sofosbuvir drug substances.Conclusion: The developed method can be successfully applied for routine analysis, quality control analysis, and also suitable for stability analysis ofDaclatasvir and Sofosbuvir in API form as per the regulatory requirements.Keywords: Daclatasvir, Sofosbuvir, Method development, Validation, Ultraviolet-visible spectrophotometry