9. Convergence Behaviour of Cardinal Exponential Spline Interpolants

We study the principal component analysis based approach introduced by Reisinger and Wittum (2007) and the comonotonic approach considered by Hanbali and Linders (2019) for the approximation of American basket option values via multidimensional partial differential complementarity problems (PDCPs). Both approximation approaches require the solution of just a limited number of low-dimensional PDCPs. It is demonstrated by ample numerical experiments that they define approximations that lie close to each other. Next, an efficient discretisation of the pertinent PDCPs is presented that leads to a favourable convergence behaviour.

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Exponential spline interpolation in characteristic based scheme for solving the advective-diffusion equation

International Journal for Numerical Methods in Fluids ◽

10.1002/1097-0363(20000615)33:3<429::aid-fld60>3.0.co;2-1 ◽

2000 ◽

Vol 33 (3) ◽

pp. 429-452 ◽

Cited By ~ 13

Author(s):

C. Zoppou ◽

S. Roberts ◽

R. J. Renka

Keyword(s):

Diffusion Equation ◽

Spline Interpolation ◽

Exponential Spline ◽

Advective Diffusion

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Dynamics of convergence behaviour in social media crisis communication – a complexity perspective

Information Technology and People ◽

10.1108/itp-10-2019-0537 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Milad Mirbabaie ◽

Stefan Stieglitz ◽

Felix Brünker

Keyword(s):

Social Media ◽

Emergency Management ◽

Crisis Communication ◽

Design Methodology ◽

Content Type ◽

The Public ◽

Analysis Techniques ◽

Twitter Data ◽

Convergence Behaviour ◽

Over Time

PurposeThe purpose of this study is to investigate communication on Twitter during two unpredicted crises (the Manchester bombings and the Munich shooting) and one natural disaster (Hurricane Harvey). The study contributes to understanding the dynamics of convergence behaviour archetypes during crises.Design/methodology/approachThe authors collected Twitter data and analysed approximately 7.5 million relevant cases. The communication was examined using social network analysis techniques and manual content analysis to identify convergence behaviour archetypes (CBAs). The dynamics and development of CBAs over time in crisis communication were also investigated.FindingsThe results revealed the dynamics of influential CBAs emerging in specific stages of a crisis situation. The authors derived a conceptual visualisation of convergence behaviour in social media crisis communication and introduced the terms hidden and visible network-layer to further understanding of the complexity of crisis communication.Research limitations/implicationsThe results emphasise the importance of well-prepared emergency management agencies and support the following recommendations: (1) continuous and (2) transparent communication during the crisis event as well as (3) informing the public about central information distributors from the start of the crisis are vital.Originality/valueThe study uncovered the dynamics of crisis-affected behaviour on social media during three cases. It provides a novel perspective that broadens our understanding of complex crisis communication on social media and contributes to existing knowledge of the complexity of crisis communication as well as convergence behaviour.

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Improving ozone profile retrieval from spaceborne UV backscatter spectrometers using convergence behaviour diagnostics

Atmospheric Measurement Techniques ◽

10.5194/amt-3-1555-2010 ◽

2010 ◽

Vol 3 (6) ◽

pp. 1555-1568 ◽

Cited By ~ 13

Author(s):

B. Mijling ◽

O. N. E. Tuinder ◽

R. F. van Oss ◽

R. J. van der A

Keyword(s):

Cross Sections ◽

A Priori ◽

Computation Time ◽

External Input ◽

Computational Time ◽

Ozone Profile ◽

Global Performance ◽

Convergence Behaviour ◽

Low Cloud ◽

Average Computation Time

Abstract. The Ozone Profile Algorithm (OPERA), developed at KNMI, retrieves the vertical ozone distribution from nadir spectral satellite measurements of back scattered sunlight in the ultraviolet and visible wavelength range. To produce consistent global datasets the algorithm needs to have good global performance, while short computation time facilitates the use of the algorithm in near real time applications. To test the global performance of the algorithm we look at the convergence behaviour as diagnostic tool of the ozone profile retrievals from the GOME instrument (on board ERS-2) for February and October 1998. In this way, we uncover different classes of retrieval problems, related to the South Atlantic Anomaly, low cloud fractions over deserts, desert dust outflow over the ocean, and the intertropical convergence zone. The influence of the first guess and the external input data including the ozone cross-sections and the ozone climatologies on the retrieval performance is also investigated. By using a priori ozone profiles which are selected on the expected total ozone column, retrieval problems due to anomalous ozone distributions (such as in the ozone hole) can be avoided. By applying the algorithm adaptations the convergence statistics improve considerably, not only increasing the number of successful retrievals, but also reducing the average computation time, due to less iteration steps per retrieval. For February 1998, non-convergence was brought down from 10.7% to 2.1%, while the mean number of iteration steps (which dominates the computational time) dropped 26% from 5.11 to 3.79.

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