Michael Griebel and Veronika Thurner
We study the sparse grid combination technique as an efficient methodfor the solution of fluid dynamics problems. The combination technique needsonlyO(h–1n(log(h–1n))d–1)grid…
Abstract
We study the sparse grid combination technique as an efficient method for the solution of fluid dynamics problems. The combination technique needs only O(h–1n(log(h–1n))d–1) grid points for d‐dimensional problems, instead of O(h–dn) grid points used by the full grid method. Here, hn = 2–n denotes the mesh width of the grids. Furthermore, provided that the solution is sufficiently smooth, the accuracy (with respect to the L2‐ and the L∞‐norm) of the sparse grid combination solution is O(hαn(log(h–1n))d–1), which is only slightly worse than O(hαn) obtained by the full grid solution. Here, α includes the order of the underlying discretization scheme, as well as the influence of singularities. Thus, the combination technique is very economic on both storage requirements and computing time, but achieves almost the same accuracy as the usual full grid solution. Another advantage of the combination technique is that only simple data structures are necessary. Where other sparse grid methods need hierarchical data structures and thus specially designed solvers, the combination method handles merely d‐dimensional arrays. Thus, the implementation of the combination technique can be based on any “black box solver”. However, for reasons of efficiency, an appropriate multigrid solver should be used. Often, fluid dynamics problems have to be solved on rather complex domains. A common approach is to divide the domain into blocks, in order to facilitate the handling of the problem. We show that the combination technique works on such blockstructured grids as well. When dealing with complicated domains, it is often desirable to grade a grid around a singularity. Graded grids are also supported by the combination technique. Finally, we present the first results of numerical experiments for the application of the combination method to CFD problems. There, we consider two‐dimensional laminar flow problems with moderate Reynolds numbers, and discuss the advantages of the combination method.
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This column seeks to look at the case of a long‐standing project to arrange document delivery between US and German libraries. This case represents the broader problem of…
Abstract
Purpose
This column seeks to look at the case of a long‐standing project to arrange document delivery between US and German libraries. This case represents the broader problem of international document delivery.
Design/methodology/approach
The primary methodology is anthropological. The column considers cultural and economic differences and assumptions, as well as differences between the law codes that enable document delivery.
Findings
Document delivery is at least temporarily impossible from Germany to the USA owing to lawsuits and agreements within Germany. The introduction of Digital Rights Management (DRM) software into new agreements may lead to programs with seriously abbreviated rights for users.
Originality/value
The case of US‐German document delivery has particular importance because of the amount of research contact between the two countries and because of the substantial differences in their legal systems and their copyright laws.
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Sabeen Hussain Bhatti, Dmitriy Vorobyev, Ramsha Zakariya and Michael Christofi
As an integral part of intellectual capital (IC), social capital (SC) has been studied as an asset crucial to social relationships among individuals and groups of individuals…
Abstract
Purpose
As an integral part of intellectual capital (IC), social capital (SC) has been studied as an asset crucial to social relationships among individuals and groups of individuals, which in turn have a significant impact on organizational performance outcomes. This study investigates the impact of organizational social capital (OSC) on employee creativity through the mediation role of knowledge sharing (KS) and moderation of work meaningfulness (WM).
Design/methodology/approach
The authors base the analysis on employee-level data gathered via a cross-sectional survey designed for this study. The authors surveyed 217 employees of the pharmaceutical industry in Pakistan. The authors run a confirmatory factor analysis (CFA) and use structural equation modeling (SEM) and Hayes method to test the hypotheses.
Findings
The authors find that OSC positively affects employees’ willingness to share their knowledge with colleagues, which in turn has a positive effect on employee creativity (EC). The results also show that the relationship between social capital and knowledge sharing is moderated by work meaningfulness.
Research limitations/implications
This study contributes to the IC in general and the SC literature in particular, by providing empirical evidence that shows how creativity could be a focal and pivotal performance outcome of organizational social capital through the moderated mediation roles of work meaningfulness and knowledge sharing.
Originality/value
The authors adopt the concept of SC from the organizational level to the individual level, examining how an individual's perception of organizational capital influences his or her creative behavior and exploring the role of KS and job meaningfulness (JM) in this relationship.
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Interest rate risk, i.e. the risk of changes in the interest rate term structure, is of high relevance in insurers' risk management. Due to large capital investments in interest…
Abstract
Purpose
Interest rate risk, i.e. the risk of changes in the interest rate term structure, is of high relevance in insurers' risk management. Due to large capital investments in interest rate sensitive assets such as bonds, interest rate risk plays a considerable role for deriving the solvency capital requirement (SCR) in the context of Solvency II. This paper seeks to address these issues.
Design/methodology/approach
In addition to the Solvency II standard model, the author applies the model of Gatzert and Martin for introducing a partial internal model for the market risk of bond exposures. After introducing calibration methods for short rate models, the author quantifies interest rate and credit risk for corporate and government bonds and demonstrates that the type of process can have a considerable impact despite comparable underlying input data.
Findings
The results show that, in general, the SCR for interest rate risk derived from the standard model of Solvency II tends to the SCR achieved by the short rate model from Vasicek, while the application of the Cox, Ingersoll, and Ross model leads to a lower SCR. For low‐rated bonds, the internal models approximate each other and, moreover, show a considerable underestimation of credit risk in the Solvency II model.
Originality/value
The aim of this paper is to assess model risk with focus on bonds in the market risk module of Solvency II regarding the underlying interest rate process and input parameters.