scholarly journals Lightning Solvers for Potential Flows

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 227
Author(s):  
Peter J. Baddoo
Keyword(s):  
Convergence Rates ◽  
Mathematical Basis ◽  
New Class ◽  
Planar Domains ◽  
Potential Flows ◽  
Rational Function Approximation ◽  
Novel Algorithms ◽  
High Degree ◽  
Domains With Corners ◽  
Steady Potential

We present a method for computing potential flows in planar domains. Our approach is based on a new class of techniques, known as “lightning solvers”, which exploit rational function approximation theory in order to achieve excellent convergence rates. The method is particularly suitable for flows in domains with corners where traditional numerical methods fail. We outline the mathematical basis for the method and establish the connection with potential flow theory. In particular, we apply the new solver to a range of classical problems including steady potential flows, vortex dynamics, and free-streamline flows. The solution method is extremely rapid and usually takes just a fraction of a second to converge to a high degree of accuracy. Numerical evaluations of the solutions are performed in a matter of microseconds and can be compressed further with novel algorithms.

scholarly journals Upper Limits for the Luminosity of a dM Companion in AM Herculis Objects

1980 ◽  
Vol 88 ◽  
pp. 471-472
Author(s):  
S. Tapia ◽  
G. V. Coyne
Keyword(s):  
Binary Systems ◽  
Near Infrared ◽  
Close Binary ◽  
Optical Identification ◽  
New Class ◽  
Upper Limits ◽  
Infrared Spectral ◽  
Cyclotron Emission ◽  
High Degree ◽  
The Magnetic Field

SummaryThe quest for optical identification of X-ray sources has revealed a new class of variables currently formed by AM Her, AN UMa, VV Pup, and the most recent member, 2A 0311-227 (for which a variable star designation will be available soon). These objects show many of the variations common to close binary systems where mass transfer is under way. However, they are distinguished by the high degree (10 to 35 %) of linear and circular polarization observed in the optical and near infrared spectral regions. Apparently the polarization is due to cyclotron emission of electrons located in a region where the magnetic field strength is about 108 gauss.

scholarly journals Heparin Binding Proteins as Therapeutic Target: An Historical Account and Current Trends

Medicines ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 80 ◽  
Author(s):  
Giancarlo Ghiselli
Keyword(s):  
Small Molecules ◽  
Biological Function ◽  
Antithrombin Iii ◽  
Biological Effects ◽  
Structural Flexibility ◽  
Heparin Binding ◽  
New Class ◽  
High Affinity ◽  
Current Trends ◽  
High Degree

The polyanionic nature and the ability to interact with proteins with different affinities are properties of sulfated glycosaminoglycans (GAGs) that determine their biological function. In designing drugs affecting the interaction of proteins with GAGs the challenge has been to generate agents with high binding specificity. The example to emulated has been a heparin-derived pentasaccharide that binds to antithrombin-III with high affinity. However, the portability of this model to other biological situations is questioned on several accounts. Because of their structural flexibility, oligosaccharides with different sulfation and uronic acid conformation can display the same binding proficiency to different proteins and produce comparable biological effects. This circumstance represents a formidable obstacle to the design of drugs based on the heparin scaffold. The conceptual framework discussed in this article is that through a direct intervention on the heparin-binding functionality of proteins is possible to achieve a high degree of action specificity. This objective is currently pursued through two strategies. The first makes use of small molecules for which in the text we provide examples from past and present literature concerning angiogenic factors and enzymes. The second approach entails the mutagenesis of the GAG-binding site of proteins as a means to generate a new class of biologics of therapeutic interest.

Quasi-optimal convergence of AFEM based on separate marking, Part II

2015 ◽  
Vol 23 (2) ◽  
Author(s):  
Hella Rabus
Keyword(s):  
Finite Element ◽  
Solid Mechanics ◽  
Convergence Rates ◽  
Stokes Equations ◽  
Total Error ◽  
Poisson Model ◽  
Error Estimator ◽  
Adaptive Finite Element ◽  
Optimal Convergence ◽  
High Degree

AbstractVarious applications in computational fluid dynamics and solid mechanics motivate the development of reliable and efficient adaptive algorithms for nonstandard finite element methods (FEMs). Standard adaptive finite element algorithms consist of the iterative loop of the basic steps Solve, Estimate, Mark, and Refine. For separate marking strategies, this standard scheme may be universalised. The (total) error estimator is split into a volume term and an error estimator term.Since the volume term is independent of the discrete solution, an appropriate data approximation may be realised by a high degree of local mesh refinement. This observation results in a natural adaptive algorithm based on separate marking. Its quasi-optimal convergence is proven in this second part for the pure displacement problem in linear elasticity and the Stokes equations and nonconforming Crouzeix-Raviart FEM. The proofs follow the same general methodology as for the Poisson model problem in the first part of this series. The numerical experiments confirm the optimal convergence rates and reveal its flexibility.

scholarly journals Evaluation of stability and viscosity of [C2mim][DCA] based ionanocolloids

2021 ◽  
Vol 2116 (1) ◽  
pp. 012068
Author(s):  
J Pinto ◽  
E Fabre ◽  
S M S Murshed
Keyword(s):  
Heat Transfer ◽  
Silicon Oxide ◽  
High Viscosity ◽  
Deionized Water ◽  
Green Solvents ◽  
Step Method ◽  
New Class ◽  
Potential Applications ◽  
The Stability ◽  
High Degree

Abstract In the search for the optimization of heat transfer systems, Ionanocolloids (INCs) as we have termed here, have revealed as very attractive choices due to their increasingly potential applications in thermal energy areas. By definition, INCs are suspensions of nanoparticles (NPs) into Ionic Liquids (ILs). Besides a high degree of versatility and enhanced thermal properties, these new class of fluids are considered as green solvents due to their negligible vapor pressure, non-flammability and recyclability. Despite the great advantages of using these INCs, their industrial application is still a challenge due to low stability and high viscosity issues attributed to them. In this work, different Ionanocolloids were prepared by two-step method, using 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][DCA]) together with deionized water as base fluids and 3 different NPs: Titanium(IV) Oxide, Silicon Oxide and Aluminum Oxide. The stability and viscosity of these mixtures were then evaluated and the results are reported.

scholarly journals Structure aware Runge–Kutta time stepping for spacetime tents

2020 ◽  
Vol 1 (4) ◽  
Author(s):  
Jay Gopalakrishnan ◽  
Joachim Schöberl ◽  
Christoph Wintersteiger
Keyword(s):  
Convergence Rates ◽  
Hyperbolic Equations ◽  
Hyperbolic Systems ◽  
Convergence Properties ◽  
New Class ◽  
Time Stepping ◽  
New Methods ◽  
Optimal Convergence Rates ◽  
Runge Kutta ◽  
Discrete Stability

Abstract We introduce a new class of Runge–Kutta type methods suitable for time stepping to propagate hyperbolic solutions within tent-shaped spacetime regions. Unlike standard Runge–Kutta methods, the new methods yield expected convergence properties when standard high order spatial (discontinuous Galerkin) discretizations are used. After presenting a derivation of nonstandard order conditions for these methods, we show numerical examples of nonlinear hyperbolic systems to demonstrate the optimal convergence rates. We also report on the discrete stability properties of these methods applied to linear hyperbolic equations.

scholarly journals Rational Savings Account Models for Backward-Looking Interest Rate Benchmarks

Risks ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 23 ◽  
Author(s):  
Andrea Macrina ◽  
David Skovmand
Keyword(s):  
Interest Rate ◽  
Cash Flows ◽  
Rate System ◽  
Rational Form ◽  
Adjusted Risk ◽  
New Class ◽  
Discount Factors ◽  
Major Transition ◽  
Risk Free Rate ◽  
High Degree

Interest rate benchmarks are currently undergoing a major transition. The LIBOR benchmark is planned to be discontinued by the end of 2021 and superseded by what ISDA calls an adjusted risk-free rate (RFR). ISDA has recently announced that the LIBOR replacement will most likely be constructed from a compounded running average of RFR overnight rates over a period matching the LIBOR tenor. This new backward-looking benchmark is markedly different when compared with LIBOR. It is measurable only at the end of the term in contrast to the forward-looking LIBOR, which is measurable at the start of the term. The RFR provides a simplification because the cash flows and the discount factors may be derived from the same discounting curve, thus avoiding—on a superficial level—any multi-curve complications. We develop a new class of savings account models and derive a novel interest rate system specifically designed to facilitate a high degree of tractability for the pricing of RFR-based fixed-income instruments. The rational form of the savings account models under the risk-neutral measure enables the pricing in closed form of caplets, swaptions and futures written on the backward-looking interest rate benchmark.

The Intersection of Cybercrime and the Blockchain

2021 ◽  
pp. 676-699
Author(s):  
Vishnu Venkatesh ◽  
Steven Gordon
Keyword(s):  
Criminal Activity ◽  
Security Risks ◽  
New Class ◽  
Blockchain Technology ◽  
Paper Currency ◽  
High Degree

The immutability of blockchains and the transparency of their transaction records would appear to limit the benefit of exploiting them for criminal activity. However, blockchains also offer a high degree of anonymity, similar to fiat paper currency; the technology was intended to facilitate trustless transactions. Coupled with a global, borderless reach, blockchains have become an enabler of cybercrime. They are a new class of assets that, like all other assets, possess security risks and become potential targets of attack. In particular, cryptocurrencies, which depend on blockchain technology, provide significant incentives for attack because of their value. The goals of this chapter are to identify and classify blockchain-based cybercrimes and to explore the avenues for protecting against them at individual, organizational, and policy levels.

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