Extrapolation Concept Research Articles

Tabu search exploiting local optimality in binary optimization

A variety of strategies have been proposed for overcoming local optimality in metaheuristic search. This paper examines characteristics of moves that can be exploited to make good decisions about steps that lead away from a local optimum and then lead toward a new local optimum. We introduce strategies to identify and take advantage of useful features of solution history with an adaptive memory metaheuristic, to provide rules for selecting moves that offer promise for discovering improved local optima. Our approach uses a new type of adaptive memory based on a construction called exponential extrapolation. The memory operates by means of threshold inequalities that ensure selected moves will not lead to a specified number of most recently encountered local optima. Associated thresholds are embodied in choice rule strategies that further exploit the exponential extrapolation concept and open a variety of research possibilities for exploration. The considerations treated in this study are illustrated in an implementation to solve the Quadratic Unconstrained Binary Optimization (QUBO) problem. We show that the AA algorithm obtains an average objective gap of 0.0315% to the best known values for the 21 largest Palubeckis instances. This solution quality is considered to be quite attractive because less than 20 s on average are taken by AA, which is 1 to 2 orders of magnitude less than the time required by most algorithms reporting the best known results.

Effectiveness and safety of switching to adalimumab biosimilar ABP 501 in Crohn's disease: the extrapolation concept.

We sincerely thank Viscido et al. for their appropriate and sharable comments on our recent study on adalimumab biosimilar ABP 501 in Crohn's disease (CD). The use of a biosimilar in inflammatory disorders is one of the current main topics, given the great opportunity to save resources that can be invested in innovative drugs and the ethical problems that non-medical switching can generate.

Extrapolation of imidacloprid toxicity between soils by exposing Folsomia candida in soil pore water

Soil properties like organic matter (OM) content show great variation, making it hard to predict the fate and effects of a chemical in different soils. We therefore addressed the question: can we remove the complexity of the soil matrix and yet accurately predict soil toxicity from porewater exposures? Folsomia candida was exposed to imidacloprid in natural (LUFA 2.2 [4.02% OM], Grassland [12.6% OM]) and artificial soils (OECD 5 [6.61% OM], OECD 10 [10.8% OM]), in pore water extracted from spiked LUFA 2.2 soil and in water. Toxicity decreased with increasing OM content except for Grassland soil, which had the highest OM content but the lowest clay content, suggesting a role of clay minerals in the binding of imidacloprid. Distribution coefficients for imidacloprid based on toxicity (Toxicity-Kd) were derived by comparing effect concentrations in LUFA 2.2 soil and in water. Using these Toxicity-Kds to recalculate soil LC50s/EC50s to porewater concentrations, the differences in LC50/EC50s almost disappeared. The recalculated porewater LC50s did not differ by more than a factor of 0.55–1.43 from the LC50 obtained upon water exposure. This similarity suggests that the toxicity in the soil is dependent on porewater concentrations and can be obtained from water exposure. The porewater test and the corresponding “pore-water extrapolation concept” developed in this study may be used to predict the toxicity of chemicals in the soil and extrapolate among different soils.

Paediatric Medicines: Regulatory and Scientific Issues.

In the past, dosage regimens authorized for adults were extrapolated to children relying mainly on empirical dosage adjustments. However, children are not small adults, but a distinct and heterogeneous group in terms of physiology, disease occurrence, pharmacokinetics, pharmacodynamics and also psychological, cognitive, and behavioral aspects. Even though it would be helpful to know the physiological changes and the special drug treatment needs in children, this task could not be performed due to ethical reasons. Important issues to consider for the development of paediatric drug products refer to the administration of the accurate dose, the use of the appropriate excipients, and acceptability. The latter is crucial and taste-screening methods (like electronic tongues) have been developed. A new era in paediatric medicines started with the entry into force of paediatric regulations. In the early '80s, the FDA started the set-up of a regulatory framework by authorizing issues like the Paediatric Rule, the Best Pharmaceuticals for Children Act, the Paediatric Research Equity Act, and the Food and Drug Administration Safety and Innovation Act. Similar efforts have been made in the EU, mainly through the entry into force of the Paediatric Regulation and the establishment of the Paediatric Committee, the Paediatric Investigation Plan, the Paediatric Use Marketing Authorization, and the European Paediatric Research Network. Other efforts to bridge the gap, between knowledge in adults and the children's special requirements, include the extrapolation concept of safety/efficacy aspects, the application of modeling/simulation approaches in paediatric drug development, and the development of a paediatric Biopharmaceutics Classification Scheme.

Steering vehicle control and road bank angle estimation: application for diagnosis of vehicle limits in bend

This paper deals with the diagnosis of the critical driving situations. This work is divided into three parts: the first one presents two steering controllers using the sliding mode and the switched H∞ controllers, the second one describes an unknown input sliding mode observer, while the last one presents an approach to the diagnosis of critical driving situations. All existence conditions are established using the Lyapunov approach. Simulations are conducted to highlight the efficiency of the proposed approach using the experimental data recorded by an instrumented Peugeot 307 laboratory car. The diagnosis of the critical driving situations is achieved by the speed extrapolation concept using simultaneously a non–linear model, a steering control and road bank observer. The speed extrapolation concept is used in order to evaluate situations under high dynamic loads on a bend, using stability of the sideslip motion.

Investigation of the Slow Crack Growth Behavior of Static and Cyclic Loaded Specimens of Polyethylene by 2D and 3D Optical Fracture Surface Analysis

AbstractSummary: A fracture surface investigation was conducted to study the applicability of cracked round bar (CRB) specimens for an accelerated extrapolation concept for a lifetime assessment of polyethylene (PE) pipes. Scanning electron microscopy and topography metrology with InfiniteFocus were used to study the slow crack growth behavior in CRB specimens at different loading conditions. The results confirm the compliance of the CRB test with the requirements of linear elastic fracture mechanics.

Index of Resolution Quality for Large Eddy Simulations

In the light of rapidly increasing applications of large-eddy simulations (LES), it is deemed necessary to impose some quality assessment measures for such studies. The verification of LES calculations is difficult because of the fact that both the subgrid scale (SGS) model contribution and numerical discretization errors are functions of the grid resolution. In this study, various indexes of quality measures, hereafter referred to as LES̱IQ, are proposed. The recommended LES̱IQ is based on the Richardson extrapolation concept. This method has been applied to various cases and the calculated LES̱IQ results are compared with the relative total experimental and direct numerical simulation (DNS) error, defined as IQ̱EX and IQ̱DNS, respectively. It is postulated that in practical applications of LES, numerical dissipation will always be a significant part of the overall dissipation, and it must be accounted for in any assessment of the quality of LES. It is further suggested that LES̱IQ of 75% to 85% can be considered adequate for most engineering applications that typically occur at high Reynolds numbers; the proposed index is an indicator of good resolution (i.e., verification), but not necessarily a good or accurate model (i.e., validation).