Automated parameters for troubled-cell indicators using outlier detection

In Vuik and Ryan (2014) we studied the use of troubled-cell indicators for discontinuity detection in nonlinear hyperbolic partial differential equations and introduced a new multiwavelet technique to detect troubled cells. We found that these methods perform well as long as a suitable, problem-dependent parameter is chosen. This parameter is used in a threshold which decides whether or not to detect an element as a troubled cell. Until now, these parameters could not be chosen automatically. The choice of the parameter has impact on the approximation: it determines the strictness of the troubled-cell indicator. An inappropriate choice of the parameter will result in detection (and limiting) of too few or too many elements. The optimal parameter is chosen such that the minimal number of troubled cells is detected and the resulting approximation is free of spurious oscillations. In this paper we will see that for each troubled-cell indicator the sudden increase or decrease of the indicator value with respect to the neighboring values is important for detection. Indication basically reduces to detecting the outliers of a vector (one dimension) or matrix (two dimensions). This is done using Tukey's boxplot approach to detect which coefficients in a vector are straying far beyond others (Tukey, 1977). We provide an algorithm that can be applied to various troubled-cell indication variables. Using this technique the problem-dependent parameter that the original indicator requires is no longer necessary as the parameter will be chosen automatically

Historical roots of Agile methods: where did “Agile thinking” come from?

The appearance of Agile methods has been the most noticeable change to software process thinking in the last fifteen years [16], but in fact many of the “Agile ideas” have been around since 70’s or even before. Many studies and reviews have been conducted about Agile methods which ascribe their emergence as a reaction against traditional methods. In this paper, we argue that although Agile methods are new as a whole, they have strong roots in the history of software engineering. In addition to the iterative and incremental approaches that have been in use since 1957 [21], people who criticised the traditional methods suggested alternative approaches which were actually Agile ideas such as the response to change, customer involvement, and working software over documentation. The authors of this paper believe that education about the history of Agile thinking will help to develop better understanding as well as promoting the use of Agile methods. We therefore present and discuss the reasons behind the development and introduction of Agile methods, as a reaction to traditional methods, as a result of people's experience, and in particular focusing on reusing ideas from histor

Why are Some Regions More Innovative than Others? The Role of Firm Size Diversity

Large labs may spawn spin-outs caused by innovations deemed unrelated to the firm's overall business. Small labs generate demand for specialized services that lower entry costs for others. We develop a theoretical framework to study the interplay of these two localized externalities and their impact on regional innovation. We examine MSA-level patent data during the period 1975-2000 and find that innovation output is higher where large and small labs coexist. The finding is robust to across-region as well as within-region analysis, IV analysis, and the effect is stronger in certain subsamples consistent with our explanation but not the plausible alternatives.

Public & Private Spillovers, Location and the Productivity of Pharmaceutical Research

While there is widespread agreement among economists and management scholars that knowledge spillovers exist and have important economic consequences, researchers know substantially less about the "micro mechanisms" of spillovers -- about the degree to which they are geographically localized, for example, or about the degree to which spillovers from public institutions are qualitatively different from those from privately owned firms (Jaffe, 1986; Krugman, 1991; Jaffe et al., 1993; Porter, 1990). In this paper we make use of the geographic distribution of the research activities of major global pharmaceutical firms to explore the extent to which knowledge spills over from proximate private and public institutions. Our data and empirical approach allow us to make advances on two dimensions. First, by focusing on spillovers in research productivity (as opposed to manufacturing productivity), we build closely on the theoretical literature on spillovers that suggests that knowledge externalities are likely to have the most immediate impact on the production of ideas (Romer, 1986; Aghion & Howitt, 1997). Second, our data allow us to distinguish spillovers from public research from spillovers from private, or competitively funded research, and to more deeply explore the role that institutions and geographic proximity play in driving knowledge spillovers.

Acoustic fatigue and sound transmission characteristics of a ram composite panel design

An experimental study to determine the acoustic fatigue characteristics of a flat multi-layered structural panel is described. The test panel represented a proposed design for the outer skin of a research application module to be housed within the space shuttle orbiter vehicle. The test specimen was mounted in one wall of the Wyle 100,000 cu ft reverberation room and exposed to a broadband acoustic environment having an overall level of 145 db. The test panel was exposed to nine separate applications of the acoustic environment, each application consisting of 250 seconds duration. Upon completion of the ninth test run, the specimen was exposed to a simulated micrometeoroid impact near the panel center. One additional test run of 250 seconds duration was then performed to complete the overall simulation of 50 flight missions. The experimental results show that no significant fatigue damage occurred until the test specimen was exposed to a simulated micrometeoroid impact. The intermediate foam layer forming the core of the test specimen suffered considerable damage due to this impact, causing a marked variation in the dynamic characteristics of the overall test panel. During the final application of the acoustic environment, the strain and acceleration response spectra showed considerable variation from those spectra obtained prior to impact of the panel. Fatigue damage from acoustic loading however, was limited to partial de-bonding around the edges of the composite panel

Simulating Turbulence Using the Astrophysical Discontinuous Galerkin Code TENET

In astrophysics, the two main methods traditionally in use for solving the Euler equations of ideal fluid dynamics are smoothed particle hydrodynamics and finite volume discretization on a stationary mesh. However, the goal to efficiently make use of future exascale machines with their ever higher degree of parallel concurrency motivates the search for more efficient and more accurate techniques for computing hydrodynamics. Discontinuous Galerkin (DG) methods represent a promising class of methods in this regard, as they can be straightforwardly extended to arbitrarily high order while requiring only small stencils. Especially for applications involving comparatively smooth problems, higher-order approaches promise significant gains in computational speed for reaching a desired target accuracy. Here, we introduce our new astrophysical DG code TENET designed for applications in cosmology, and discuss our first results for 3D simulations of subsonic turbulence. We show that our new DG implementation provides accurate results for subsonic turbulence, at considerably reduced computational cost compared with traditional finite volume methods. In particular, we find that DG needs about 1.8 times fewer degrees of freedom to achieve the same accuracy and at the same time is more than 1.5 times faster, confirming its substantial promise for astrophysical applications.Comment: 21 pages, 7 figures, to appear in Proceedings of the SPPEXA symposium, Lecture Notes in Computational Science and Engineering (LNCSE), Springe

The Football Association’s Child Protection in Football Research Project 2002-2006: Rationale, design and first year results

In common with most sport organisations, the English Football Association has come relatively recently to the issue of child protection. Abuses of various kinds have been known about in the sport for many years but, until the late 1990s, very little systematic work was undertaken to address this. The launch of a Child Protection Strategy by the Engalish FA in May 2000 reflected recognition by those in authority within the sport that child abuse and protection were properly the subject of football policy and should become embedded in all aspects of the affiliated game. In addition to adopting child protection, the then-Chief Executive Officer of the FA made a commitment to evidence-based policy in his strategic plan for the game. In line with this commitment, the FA commissioned a 5 year study of the impact of child protection on the game, the first year of which constituted an audit of the state of child protection in the affiliated game. Data were collected through 11 internet surveys, 32 club case studies, over 200 interviews with various stakeholders and an analysis of 132 case files for child abuse referrals. This paper sets out the context of child protection in sport more generally and the background to the FA's child protection reseach project in particular. It also presents selected first year results for key stakeholder groups

A mix of small and large firms can be key to regional innovation

Areas such as Silicon Valley and Boston are often held up as examples of innovative regions to be emulated, but what makes them this way? By analysing patent data on computers and communication technology, Ajay K. Agrawal, Iain Cockburn, Alberto Galasso, and Alexander Oettl, argue that the mix of large and small firms in a region is very important to regional innovation. He writes that regions where a number of small and large lists coexist are more productive in terms of innovation, when compared to those that have only a small number of large firms or a large number of small ones

Measuring the impact of child protection through Activation States

Child protection (CP) has risen to the top of the UK sports policy agenda in the past four years and the Football Association has invested in this major strategy as part of its commitment to “use the power of football to build a better future” (FA, 2000a). Evidencing the impact of child protection is, however, a complex task, exacerbated by the dearth of measurement tools that exist for this purpose in sport. This article presents a new model of ‘Activation States’ that has been designed and used to measure shifts in football culture as child protection has begun to impact upon the sport. The model is used to map changes over time related to the knowledge, feelings, actions and discourses of key stakeholders in football. The research for which the model was designed is a longitudinal study, commissioned by the English Football (soccer) Association, on the impact of the organisation’s child protection strategy on the culture of soccer. Sample data from the project are used to illustrate the model and to examine its potential and limitations as a tool for measuring impacts in child protection and other social inclusion themes