Distributed computational fluid dynamics

Computational fluid dynamics simulations of relevance to jet-engine design, for instance, are extremely computationally demanding and the use of large-scale distributed computing will allow the solution of problems that cannot be tackled using current resources. It is often appropriate to leave the large datasets generated by CFD codes local to the compute resource in use at the time. This naturally leads to a distributed database of results that will need to be federated as a coherent resource for the engineering community. We describe the use of Globus and Condor within Cambridge for sharing computer resources, progress on defining XML standards for the annotation of CFD datasets and a distributed database framework for them

Dental Students’ Attitude towards Problem-Based Learning before and after Implementing 3D Electronic Dental Models

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Fourier-cosine method for ruin probabilities

In theory, ruin probabilities in classical insurance risk models can be expressed in terms of an infinite sum of convolutions, but its inherent complexity makes efficient computation almost impossible. In contrast, Fourier transforms of convolutions could be evaluated in a far simpler manner. This feature aligns with the heuristic of the recently popular work by Fang and Oosterlee, in particular, they developed a numerical method based on Fourier transform for option pricing. We here promote their philosophy to ruin theory. In this paper, we not only introduce the Fourier-cosine method to ruin theory, which has O(n)O(n) computational complexity, but we also enhance the error bound for our case that are not immediate from Fang and Oosterlee (2009). We also suggest a robust method on estimation of ruin probabilities with respect to perturbation of the moments of both claim size and claim arrival distributions. Rearrangement inequality will also be adopted to amplify the Fourier-cosine method, resulting in an effective global estimation.postprin

Fourier-cosine method for Gerber-Shiu functions

In this article, we provide a systematic study on effectively approximating the Gerber–Shiu functions, which is a hardly touched topic in the current literature, by incorporating the recently popular Fourier-cosine method. Fourier-cosine method has been a prevailing numerical method in option pricing theory since the work of Fang and Oosterlee (2009). Our approximant of Gerber–Shiu functions under Lévy subordinator model has O(n)O(n) computational complexity in comparison with that of O(nlogn)O(nlogn) via the fast Fourier transform algorithm. Also, for Gerber–Shiu functions within our proposed refined Sobolev space, we introduce an explicit error bound, which seems to be absent from the literature. In contrast with our previous work (Chau et al., 2015), this error bound is more conservative without making heavy assumptions on the Fourier transform of the Gerber–Shiu function. The effectiveness of our result will be further demonstrated in the numerical studies.postprin

Ruin probability under compound Poisson models with random discount factor

In this article, we consider a compound Poisson insurance risk model with a random discount factor. This model is also known as the compound filtered Poisson model. By using some stochastic analysis techniques, a convergence result for the discounted surplus process, an expression for the ruin probability, and the upper bounds for the ruin probability are obtained.published_or_final_versio

Qualitative and quantitative analysis of the students’ perceptions to the use of 3D electronic models in problem-based learning

Faculty of Dentistry of the University of Hong Kong has introduced innovative blended problem-based learning (PBL) with the aid of 3D electronic models (e-models) to Bachelor of Dental Surgery (BDS) curriculum. Statistical results of pre- and post-semester questionnaire surveys illustrated compatibility of e-models in PBL settings. The students’ importance ratings of two objectives “Complete assigned tasks on time” and “Active listener”, and twenty-two facilitator evaluation items including critical thinking and group problem-solving skills had increased significantly. The students’ PBL preparation behavior, attentions to problem understanding, problem analysis, and learning resource quality were also found to be related to online support of e-models and its software. Qualitative analysis of open-ended questions with visual text analytic software “Leximancer” improved validity of statistical results. Using e-model functions in treatment planning, problem analysis and giving instructions provided a method of informative communication. Therefore, it is critical for the faculty to continuously provide facilitator training and quality online e-model resources to the students.published_or_final_versio

Application of PGA on optimization of distribution of shopping centers

Series: Lecture notes in computer scienceAuthor name used in this publication: Chun-Tian ChengAuthor name used in this publication: Kwokwing Chau2004-2005 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

Identification of five novel WASP mutations in Chinese families with Wiskott-Aldrich syndrome.

The Wiskott-Aldrich Syndrome (WAS) is an X-linked recessive immunodeficiency caused by mutation in the gene encoding WAS protein (WASP). The disease is characterized by eczema, thrombocytopenia and severe immunodeificency and is associated with extensive clinical heterogeneity. Mutation studies indicated that the mutated genotypes are also highly variable. In this study, we performed PCR-direct sequencing analysis of the WAS gene in six unrelated Chinese families. Five novel mutations identified, included two nonsense mutations (506C-->T, 1388-->T), a small insertion (685-686insCGCA) and two single-base deletions (384delT, 984delC). All of the mutations are predicted to lead to premature translational termination of WASP. Copyright 2002 Wiley-Liss, Inc.postprin

Holographic colour prints for enhanced optical security by combined phase and amplitude control.

Conventional optical security devices provide authentication by manipulating a specific property of light to produce a distinctive optical signature. For instance, microscopic colour prints modulate the amplitude, whereas holograms typically modulate the phase of light. However, their relatively simple structure and behaviour is easily imitated. We designed a pixel that overlays a structural colour element onto a phase plate to control both the phase and amplitude of light, and arrayed these pixels into monolithic prints that exhibit complex behaviour. Our fabricated prints appear as colour images under white light, while projecting up to three different holograms under red, green, or blue laser illumination. These holographic colour prints are readily verified but challenging to emulate, and can provide enhanced security in anti-counterfeiting applications. As the prints encode information only in the surface relief of a single polymeric material, nanoscale 3D printing of customised masters may enable their mass-manufacture by nanoimprint lithography

Pseudolaric acid B as a new class of microtubule destabilizing agent and an effective anti-tumor compound in vivo

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