357,876 research outputs found
The structured phase of concurrency
This extended abstract summarizes the state-of-the-art solution to the structuring problem for models that describe existing real world or envisioned processes. Special attention is devoted to models that allow for the true concurrency semantics. Given a model of a process, the structuring problem deals with answering the question of whether there exists another model that describes the process and is solely composed of structured patterns, such as sequence, selection, option for simultaneous execution, and iteration. Methods and techniques for structuring developed by academia as well as products and standards proposed by industry are discussed. Expectations and recommendations on the future advancements of the structuring problem are suggested
The non-codified use of Problem Structuring Methods and the need for a generic constitutive definition
When we use a PSM what is it we are actually doing? An answer to this question would enable the PSM community to considerably enlarge the available source of case studies by the inclusion of examples of non-codified PSM use. We start from Checkland’s own proposal for a “constitutive definition” of SSM, which originated from trying to answer the question of knowing when a claim of SSM use was legitimate. By extending this idea to a generic constitutive definition for all PSMs leads us to propose a self-consistent labelling schema for observed phenomena arising from PSMs in action. This consists of a set of testable propositions, which, through observation of putative PSM use, can be used to assess validity of claims of PSM use. Such evidential support for the propositions as may be found in putative PSM use can then make it back into a broader axiomatic formulation of PSMs through the use of a set-theoretic approach, which enables our method to scale to large data sets. The theoretical underpinning to our work is in causal realism and middle range theory. We illustrate our approach through the analysis of three case studies drawn from engineering organisations, a rich source of possible non-codified PSM use. The combination of a method for judging cases of non-codified PSM use, sound theoretical underpinning, and scalability to large data sets, we believe leads to a demystification of PSMs and should encourage their wider use
Understanding behaviour in problem structuring methods interventions with activity theory
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This article argues that OR interventions, particularly problem structuring methods (PSM), are complex events that cannot be understood by conventional methods alone. In this paper an alternative approach is introduced, where the units of analysis are the activity systems constituted by and constitutive of PSM interventions. The paper outlines the main theoretical and methodological concerns that need to be appreciated in studying PSM interventions. The paper then explores activity theory as an approach to study them. A case study describing the use of this approach is provided
Convex Structuring Element Decomposition for Single Scan Binary Mathematical Morphology
International audienceThis paper presents a structuring element decomposition method and a corresponding morphological erosion algorithm able to compute the binary erosion of an image using a single regular pass whatever the size of the convex structuring element. Similarly to classical dilation-based methods, the proposed decomposition is iterative and builds a growing set of structuring elements. The novelty consists in using the set union instead of the Minkowski sum as the elementary structuring element construction operator. At each step of the construction, already-built elements can be joined together in any combination of translations and set unions. There is no restrictions on the shape of the structuring element that can be built. Arbitrary shape decompositions can be obtained with existing genetic algorithms with an homogeneous construction method. This paper, however, addresses the problem of convex shape decomposition with a deterministic method
Asset and Liability Modeling for Participating Policies with Guarantees
We study the problem of asset and liability management of participating insurance policies with guarantees. We develop a scenario optimization model for integrative asset and liability management, analyze the tradeoffs in structuring such policies, and study alternative choices in funding them. The nonlinearly constrained optimization model can be linearized through closed form solutions of the dynamic equations. Thus large-scale problems are solved with standard methods. We report on an empirical analysis of policies offered by Italian insurers. The optimized model results are in general agreement with current industry practices. However, some inefficiencies are identified and potential improvements are highlighted.
Reassessing the scope of OR practice:the influences of problem structuring methods and the analytics movement
This paper argues that if OR is to prosper it needs to more closely reflect the needs of organizations and its practitioners. Past research has highlighted a gap between theoretical research developments, applications and the methods most frequently used in organizations. The scope of OR applications has also been contested with arguments as to the expanding boundaries of OR. But despite this, anecdotal evidence suggests that OR has become marginalized in many contexts. In order to understand these changes, IFORS (International Federation of OR Societies) in 2009 conducted a survey of global OR practice. The aim was to provide current evidence on the usage of OR tools, areas of application, and the barriers to OR’s uptake, as well as the educational background of OR practitioners. Results presented here show practitioners falling into three segments, which can be loosely characterized as those practicing ‘traditional’ OR, those adopting a range of softer techniques including Problem Structuring Methods (PSMs), and a Business Analytics cluster. When combined with other recent survey evidence, the use of PSMs and Business Analytics is apparently extending the scope of OR practice. In particular, the paper considers whether the Business Analytics movement, with an overlapping skill set to traditional OR but with a fast growing organizational base, offers a route to diminishing the gap between academic research and practice. The paper concludes with an exploration of whether this represents not just an opportunity for OR but also a serious challenge to its established practices
Helping Business Schools Engage with Real Problems: The Contribution of Critical Realism and Systems Thinking
The world faces major problems, not least climate change and the financial crisis, and business schools have been criticised for their failure to help address these issues and, in the case of the financial meltdown, for being causally implicated in it. In this paper we begin by describing the extent of what has been called the rigour/relevance debate. We then diagnose the nature of the problem in terms of historical, structural and contextual mechanisms that initiated and now sustain an inability of business schools to engage with real-world issues. We then propose a combination of measures, which mutually reinforce each other, that are necessary to break into this vicious circle – critical realism as an underpinning philosophy that supports and embodies the next points; holism and transdisciplinarity; multimethodology (mixed-methods research); and a critical and ethical-committed stance. OR and management science have much to contribute in terms of both powerful analytical methods and problem structuring methods
Moving beyond value conflicts : systemic problem structuring in action
Value conflicts can become entrenched in a destructive pattern of mutual stigmatization, which inhibits the emergence of new understandings of the situation and actions for improvement. In extreme cases, such patterns can even lead to violence. This paper offers a new systems theory of value conflict, which suggests the possibility of three different strategies for intervention using problem structuring methods: supporting people in transcending overly narrow value judgements about what is important to them; seeking to widen people’s boundaries of the issues that they consider relevant; and attempting to challenge stereotyping and stigmatization by building better mutual understanding. Each of these three strategies is illustrated with practical examples from operational research projects on natural resource management in New Zealand
Virtual restoration of the Ghent altarpiece using crack detection and inpainting
In this paper, we present a new method for virtual restoration of digitized paintings, with the special focus on the Ghent Altarpiece (1432), one of Belgium's greatest masterpieces. The goal of the work is to remove cracks from the digitized painting thereby approximating how the painting looked like before ageing for nearly 600 years and aiding art historical and palaeographical analysis. For crack detection, we employ a multiscale morphological approach, which can cope with greatly varying thickness of the cracks as well as with their varying intensities (from dark to the light ones). Due to the content of the painting (with extremely many fine details) and complex type of cracks (including inconsistent whitish clouds around them), the available inpainting methods do not provide satisfactory results on many parts of the painting. We show that patch-based methods outperform pixel-based ones, but leaving still much room for improvements in this application. We propose a new method for candidate patch selection, which can be combined with different patch-based inpainting methods to improve their performance in crack removal. The results demonstrate improved performance, with less artefacts and better preserved fine details
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