Mostrando recursos 101 - 120 de 188.889

  1. A post‐mortem on the predictions: Criteria, complaints, and compliments

    James Lee Ray
    Rational choice, or expected utility models have garnered considerable skepticism in many quarters in recent years. Much of that skepticism is deserved. However, the model on which the forecasts in this collection are based is different from many of its competitors in ways which address quite directly the shortcomings that have generated most of the skepticism. Attempts to apply this model can be evaluated according to several criteria, such as the information provided about the experts that generate the data, whether or not the actual data on which the forecasts are based are provided to readers, whether those numbers or...

  2. Profiles of States as Fuzzy Sets: Methodological Refinement of Lateral Pressure Theory

    Anne-Katrin Wickboldt; Nazli Choucri
    One of the most serious challenges in international relations pertains to the theory and measurement of transformation and change. This paper proposes, and then develops a conceptual and methodological extension in the measurement of change within and across states as postulated by lateral pressure theory. It argues, and shows, that by conceptualizing the profiles of states identified by lateral pressure theory using fuzzy logic, we can systematically and precisely locate and track relative changes in the distribution of states within and across profile spaces, across geographical regions, as well as over time. This may be an important step toward identifying...

  3. Probing the Democratic Peace Argument Using Linguistic Fuzzy Logic

    Badredine Arfi
    Why have the numerous debates on the “democratic peace” remained inconclusive? In addressing this question, the paper examines causality in social sciences by using propositional calculus in the framework of linguistic fuzzy logic. The paper does this by taking into account the possibility that some causal relations might be more or less of a sufficient type while others might be more or less of a necessary type, and while still others might be of both types to a lesser or greater degree of truth. The paper shows that depending on how much more or less democratic the two states are,...

  4. Institutional Similarity and Interstate Conflict

    Mark Souva
    This paper makes two arguments. First, the political and economic institutions of a state affect that state's foreign policy preferences. Second, dyads with similar political and economic institutions are less likely to experience conflict than other types of dyads. After developing the logic of these arguments, I create measures of political and economic institutional similarity and test the hypotheses against the empirical record. The empirical analysis supports the argument that dyadic institutional similarity reduces the likelihood of conflict. The most noteworthy finding is that economic institutional similarity, even when the political institutions in a dyad are dissimilar, reduces the likelihood...

  5. Rebel Behavior in the Context of Interstate Competition: Exploring Day-to-Day Patterns of Political Violence in Africa

    Bryce W. Reeder
    This study develops a day-to-day theory of political violence that predicts that rebels respond strategically to the onset of interstate conflict that is directly related to a civil war. Government-initiated interstate conflict is theorized to incentivize rebels to signal their resolve, willingness to bear costs, and vulnerability of government forces. In addition, this form of interstate conflict is predicted to decrease violence against civilian populations, as it makes it more likely that rebels will need to rely on civilians for resources in the future. This is contrary to interstate conflict initiated by an external state, as this signal of third-party...

  6. Great deeds or great risks? Scientists’ social representations of nanotechnology

    Raquel Bertoldo; Claire Mays; Marc Poumadère; Nina Schneider; Claus Svendsen
    Nanotechnologies are becoming a larger presence in everyday life and are viewed by governments and economic actors as a key area for development. The theory of social representations suggests that specialist views eventually disseminate to shape representations among the public. Yet nanotechnologies remain relatively little known to the general public. The media emphasize potential benefits, while potential risks get less attention. The literature has not yet addressed whether representations by a well-informed population (scientists) are indeed structured in terms of the risk--benefit polarity that dominates research framing to date. We attempted a systematic assessment of how background knowledge about nanotechnology...

  7. A real options model of phased migration to cellular manufacturing

    Suvankar Ghosh; O. Felix Offodile
    The literature is replete with models that examine various aspects of cellular manufacturing (CM), such as optimisation of cell layouts. However, many firms may realise zero to marginal returns from CM. Given this uncertainty, the manager should first determine the value of CM to the firm before deploying it. Although traditional valuation models employing discounted cash flow analysis allow for uncertainty, they treat future investments as fixed when computing the investment’s present value. The real options (RO) logic of valuation allows the manager to exercise the option to invest in or abandon a project based on expected outcomes. Future investments...

  8. Collaborative networks: a systematic review and multi-level framework

    Christopher Durugbo
    Collaborative networks (CNs) leverage the improving sociability and usability features of information technology to enable and enhance partnering that delivers competitive solutions. This partnering is motivated by business, supply chain, market and technological evolutions that create uncertainty and pressure on independently operating firms. Accordingly, literature on CNs has enhanced practice by shedding light on the collaboration patterns that underlie CNs and the different management mechanisms that are required to cope with the complexity of CNs. The purpose of this article is to systematically review the state-of-the-art of research for CNs with a view to identifying future research potentials and directions....

  9. Grammatical evolution in developing optimal inventory policies for serial and distribution supply chains

    Michael Phelan; Seán McGarraghy
    Recently, there has been a growing literature on biologically inspired algorithms, particularly genetic algorithms and genetic programming, applied to supply chain modelling and inventory control optimisation. Due to the rigidity of the genetic algorithms approach, it is difficult to change the underlying model logic and add richness to the supply chain. While genetic programming provides a more flexible approach than that provided by genetic algorithms, to date its application has been limited to small supply chain modelling problems in relation to optimal inventory policies. This research applies Grammatical Evolution, a relatively new biologically inspired algorithm, to the field of supply...

  10. Towards a pattern in mass violence participation? An analysis of Rwandan perpetrators' accounts from the 1994 genocide

    Samuel Tanner
    In this article, I focus on the logic whereby a group of eight Hutu became involved in mass violence during the 1994 Rwandan genocide. This process is considered as a sequence of meaningful events that progressively shaped the actors' frame of analysis. As such, each sequence brings a new qualitative reality which, in turn, constitutes the platform upon which the involvement in, and the perpetration of, mass violence become acceptable and legitimate in the eyes of the perpetrators. Based on both Howard S. Becker's notion of career and Roger Petersen's analysis of resistance and rebellion, I disaggregate the entire process...

  11. Combating Anti-Statistical Thinking Using Simulation-Based Methods Throughout the Undergraduate Curriculum

    Nathan Tintle; Beth Chance; George Cobb; Soma Roy; Todd Swanson; Jill VanderStoep
    The use of simulation-based methods for introducing inferen-ce is growing in popularity for the Stat 101 course, due in part to increasing evidence of the methods ability to improve studen-ts’ statistical thinking. This impact comes from simulation-based methods (a) clearly presenting the overarching logic of inference, (b) strengthening ties between statistics and probability/mathematical concepts, (c) encouraging a focus on the entire research process, (d) facilitating student thinking about advanced statistical concepts, (e) allowing more time to explore, do, and talk about real research and messy data, and (f) acting as a firm-er foundation on which to build statistical intuition. Thus,...

  12. Beyond welfare economics: some methodological issues

    Giuseppe Munda
    When one wishes to formulate, evaluate and implement public policies, the existence of a plurality of social actors, with interest in the policy being assessed, generates a conflictual situation. How such a conflict should be dealt with? This paper defends the thesis articulated in the following points: (1) Different metrics are linked to different objectives and values. To use only one measurement unit (on the grounds of the so-called commensurability principle) for incorporating a plurality of dimensions, objectives and values, implies reductionism necessarily. (2) Point (1) can be proven as a matter of formal logic by drawing on the work...

  13. Abduction and economics: the contributions of Charles Peirce and Herbert Simon

    Ramzi Mabsout
    A constantly changing social reality means economic theories, even if correct today, need to be constantly revised, updated, or abandoned. To maintain an up-to-date understanding of its subject matter, economists have to continuously assess their theories even those that appear to be empirically corroborated. Economics could gain from a method that describes and is capable of generating novel explanatory hypotheses. A pessimistic view on the existence of such a method was famously articulated by Karl Popper in The Logic of Scientific Discovery . He wrote ‘there is no such a thing as a logical method of having ideas or a...

  14. Clandestine urbanization: reconstituting urban space in the margins of the Phoenix metropolitan area

    Nabil Kamel
    This paper illustrates everyday practices of a marginalized population in areas of interrupted urbanization. These practices arise from the coincidence of an urban form produced and reproduced according to a Fordist logic of mass production for mass consumption and a Post-Fordist society with diverse needs. The paper focuses on practices that, while reconstituting needed urban elements, remain nevertheless unsanctioned because of a rigid imaginary of how urban space ought to be lived. These practices exemplify how residents respond to existing material and institutional restrictions by adopting hidden and clandestine forms of urbanization that allow them to reconstitute their urban space....

  15. Claiming participation -- a comparative analysis of DIY urbanism in Denmark

    Louise Fabian; Kristine Samson
    The article discuss the conflicts, potentials and possible alliances of do-it-yourself (DIY) urbanism when it takes the form of spontaneous place appropriations, when it is performed as participatory urban design and when it is integrated strategically in planning. DIY urbanism and experimentation with participation are currently strong influential factors in Danish planning. The article explores the use of participatory DIY urban design in two cases: the relocation of beer drinkers in Enghave Square and the Carlsberg City development in Copenhagen, Denmark. Carlsberg City is the most thorough Danish example of how DIY urban design is employed as an investment and...

  16. Feed-forward modelling and fuzzy logic based control strategy for powertrain efficiency improvement in a parallel hybrid electric vehicle

    Meisam Amiri; Vahid Esfahanian; Mohammad Reza Hairi-Yazdi; Mohsen Esfahanian; Amir Mohammad Fazeli; Ali Nabi
    With the stricter limitations on both fuel consumption and air pollution, the advantages of a hybrid electric vehicle are becoming more evident than ever. In the present study, an energy management system for a hybrid electric vehicle is developed. Because the plant under consideration is nonlinear, multi-domain, time-varying, has multiple uncertainties and, in addition, the designed control strategy must be able to obey the driver's commands and achieve the par-internship for a new generation of vehicle regulations, the fuzzy logic approach is chosen. A feed-forward hybrid vehicle simulation model is used to demonstrate the validity and the convenience of the...

  17. Modelling, Synthesis, and Simulation of Supervisory Process Control Systems

    G. Mušic; D. Matko; B. Zupancic
    Modelling, synthesis, and simulation issues of the supervisory systems in process control are investigated in the paper. Petri nets are used as a basic modelling framework for the supervisory part of the system. It is shown how the final verification effort can be minimised by applying formal synthesis methods. A straightforward approach to the industrial implementation of the developed solutions is suggested by means of sequential function chart representation. A batch process cell case study is used to illustrate the described concepts. Corresponding continuous and discrete event models of the process cell units are developed and a co-ordinating supervisor is...

  18. Two modelling approaches of winemaking: first principle and metabolic engineering

    B. Charnomordic; R. David; D. Dochain; N. Hilgert; J.-R. Mouret; J.-M. Sablayrolles; A. Vande Wouwer
    In this article, two modelling approaches are proposed for winemaking fermentations. The first one is largely based on the first principle modelling approach and considers the main yeast physiological mechanisms. The model accurately predicts the fermentation kinetics of more than 80% of a large number of experiments performed with 20 wine yeast strains, 69 musts and different fermentation conditions. Thanks to the wide domain of validity of the model, a simulator based on this model coupled to a thermal model was developed to help winemakers to optimize tank management. It predicts the end of the fermentation and changes in the...

  19. Systematical hybrid state modelling of complex dynamical systems: The quad-I/HS framework

    Klaus J. Diepold; Franz J. Winkler; Boris Lohmann
    A three-phase modelling framework for systematically designing a general class of complex hybrid dynamical systems is proposed. The framework benefits from a recent decomposition principle, called DSM ( dependency structure matrix ), and results in a new hybrid state model paradigm supporting mathematical analyses. The two leading methods of complexity handling, modular modelling and closing under coupling , are therein combined. Each interaction is modelled as detailed as necessary by aligning the interaction knowledge to determined weighting coefficients. Proportional, functional and qualitative (linguistical) knowledge, which is included through Fuzzy-Logic , is considered. As not much is known about hybrid systems...

  20. Co-Production, Interdependence and Publicness: Extending public service-dominant logic

    John Alford
    This article argues that while the idea of public service-dominant logic (PSDL) has much to offer, there remains room to extend it. First, the article fine-tunes the argument that co-production is unavoidable in services management, by categorizing the different things co-producers provide and analysing their interdependencies. Second, it seeks to account for collectively consumed public value, which is neglected in PSDL. Third, it recognizes that far from ‘delighting’ customers, many public services entail applying the coercive authority of the state to those with whom they deal. The article proposes a reconceptualization of the notion of ‘client focus’.

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