370 research outputs found
Stabilization of clayey soil using fibre reinforcement
The paper presents experimental and numerical investigations on crack evolution during desiccation, on unsaturated, compacted and reinforced clay using natural Alfa fibres. The effect of fibre content is investigated and a comparison between experimental and numerical simulations is made. A modified model for tensile strength is updated in the finite element program CODE_BRIGHT and used to predict tensile cracks induced by desiccation on reinforced soil. The results show that the soil desiccation cracking behaviour is significantly influenced by fibre inclusion and that experimental and numerical results are in good agreement.Postprint (published version
A Note on Finite Quadrature Rules with a Kind of Freud Weight Function
We introduce a finite class of weighted quadrature rules with the
weight function |x|−2exp(−1/2) on (−∞,∞) as
∫∞−∞||−2exp(−1/2∑)()==1()+[], where are the zeros of polynomials orthogonal with respect to the introduced weight
function, are the corresponding coefficients, and [] is the error value. We show that the
above formula is valid only for the finite values of . In other words, the condition ≥{max}+1/2 must always be satisfied in order that one can apply the above quadrature
rule. In this sense, some numerical and analytic examples are also given and compared
Modeling and predicting drug pharmacokinetics in patients with renal impairment
Current guidance issued by the US FDA to assess the impact of renal impairment on the pharmacokinetics of a drug under development has recently been updated to include evaluation of drugs with nonrenal elimination routes. Renal impairment not only affects elimination of the drug in the kidney, but also the nonrenal route of drugs that are extensively metabolized in the liver. Renal failure may influence hepatic drug metabolism either by inducing or suppressing hepatic enzymes, or by its effects on other variables such as protein binding, hepatic blood flow and accumulation of metabolites. Prior simulation of the potential exposure of individuals with renal impairment may help in the selection of a safe and effective dosage regimen. In this article, we discuss the application of a systems biology approach to simulate drug disposition in subjects with renal impairment. © 2011 Expert Reviews Ltd
Interaction between domperidone and ketoconazole : toward prediction of consequent QTc prolongation Using purely "In vitro" information
We aimed to investigate the application of combined mechanistic pharmacokinetic (PK) and pharmacodynamic (PD) modeling and simulation in predicting the domperidone (DOM) triggered pseudo-electrocardiogram modification in the presence of a CYP3A inhibitor, ketoconazole (KETO), using in vitro–in vivo extrapolation. In vitro metabolic and inhibitory data were incorporated into physiologically based pharmacokinetic (PBPK) models within Simcyp to simulate time course of plasma DOM and KETO concentrations when administered alone or in combination with KETO (DOM+KETO). Simulated DOM concentrations in plasma were used to predict changes in gender-specific QTcF (Fridericia correction) intervals within the Cardiac Safety Simulator platform taking into consideration DOM, KETO, and DOM+KETO triggered inhibition of multiple ionic currents in population. Combination of in vitro–in vivo extrapolation, PBPK, and systems pharmacology of electric currents in the heart was able to predict the direction and magnitude of PK and PD changes under coadministration of the two drugs although some disparities were detected
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Phasor Measurement Units Optimal Placement and Performance Limits for Fault Localization
In this paper, the performance limits of faults localization are investigated using synchrophasor data. The focus is on a non-trivial operating regime where the number of Phasor Measurement Unit (PMU) sensors available is insufficient to have full observability of the grid state. Proposed analysis uses the Kullback Leibler (KL) divergence between the distributions corresponding to different fault location hypotheses associated with the observation model. This analysis shows that the most likely locations are concentrated in clusters of buses more tightly connected to the actual fault site akin to graph communities. Consequently, a PMU placement strategy is derived that achieves a near-optimal resolution for localizing faults for a given number of sensors. The problem is also analyzed from the perspective of sampling a graph signal, and how the placement of the PMUs i.e. the spatial sampling pattern and the topological characteristic of the grid affect the ability to successfully localize faults. To highlight the superior performance of presented fault localization and placement algorithms, the proposed strategy is applied to a modified IEEE 34, IEEE-123 bus test cases and to data from a real distribution grid. Additionally, the detection of cyber-physical attacks is also examined where PMU data and relevant Supervisory Control and Data Acquisition (SCADA) network traffic information are compared to determine if a network breach has affected the integrity of the system information and/or operations
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