Search results for "Theory"
showing 10 items of 24627 documents
Hadronic light-by-light contribution to $(g-2)_\mu$ from lattice QCD with SU(3) flavor symmetry
2020
We perform a lattice QCD calculation of the hadronic light-by-light contribution to $(g-2)_\mu$ at the SU(3) flavor-symmetric point $m_\pi=m_K\simeq 420\,$MeV. The representation used is based on coordinate-space perturbation theory, with all QED elements of the relevant Feynman diagrams implemented in continuum, infinite Euclidean space. As a consequence, the effect of using finite lattices to evaluate the QCD four-point function of the electromagnetic current is exponentially suppressed. Thanks to the SU(3)-flavor symmetry, only two topologies of diagrams contribute, the fully connected and the leading disconnected. We show the equivalence in the continuum limit of two methods of computin…
Comment améliorer la prévision des ventes pour le marketing ? Les apports de la théorie du chaos
2013
La littérature en marketing constate un décalage entre les avancées réalisées par les chercheurs qui développent de nouvelles méthodes de prévision des ventes, et l'usage massif de méthodes traditionnelles reposant sur l'hypothèse de linéarité des processus analysés. Cette recherche expose la contribution potentielle de la théorie du chaos à l'amélioration de la prévision des ventes. Une illustration de ces apports est proposée avec une application à la prévision des ventes de consoles de jeux vidéo au Japon. Les résultats mettent en évidence la capacité de la méthode proposée à détecter la présence de chaos dans la série et montrent la possibilité de préciser l'horizon de prévisibilité des…
Model selection using limiting distributions of second-order blind source separation algorithms
2015
Signals, recorded over time, are often observed as mixtures of multiple source signals. To extract relevant information from such measurements one needs to determine the mixing coefficients. In case of weakly stationary time series with uncorrelated source signals, this separation can be achieved by jointly diagonalizing sample autocovariances at different lags, and several algorithms address this task. Often the mixing estimates contain close-to-zero entries and one wants to decide whether the corresponding source signals have a relevant impact on the observations or not. To address this question of model selection we consider the recently published second-order blind identification proced…
Generalizability and Simplicity as Criteria in Feature Selection: Application to Mood Classification in Music
2011
Classification of musical audio signals according to expressed mood or emotion has evident applications to content-based music retrieval in large databases. Wrapper selection is a dimension reduction method that has been proposed for improving classification performance. However, the technique is prone to lead to overfitting of the training data, which decreases the generalizability of the obtained results. We claim that previous attempts to apply wrapper selection in the field of music information retrieval (MIR) have led to disputable conclusions about the used methods due to inadequate analysis frameworks, indicative of overfitting, and biased results. This paper presents a framework bas…
An Information system design product theory for the abstract class of integrated requirements and delivery management systems
2014
Information and Communications Technology-enabled international sourcing of software-intensive systems and services (eSourcing) is increasingly used as a means of adding value, reducing costs, sharing risks, and achieving strategic aims. To maximally reap the benefits from eSourcing and to mitigate the risks, providers and clients have to be aware of and build capabilities for the eSourcing life-cycle. China is in a position to become a superpower for eSourcing service provisioning, but most Chinese eSourcing service providers are small or medium-sized and typically work for larger intermediaries instead of end-clients, limiting their business and capabilities development. The extant litera…
Employees’ adherence to information security policies: An exploratory field study
2014
The key threat to information security comes from employees who do not comply with information security policies. We developed a new multi-theory based model that explained employees' adherence to security policies. The paradigm combines elements from the Protection Motivation Theory, the Theory of Reasoned Action, and the Cognitive Evaluation Theory. We validated the model by using a sample of 669 responses from four corporations in Finland. The SEM-based results showed that perceived severity of potential information security threats, employees' belief as to whether they can apply and adhere to information security policies, perceived vulnerability to potential security threats, employees…
Measuring Distraction at the Levels of Tactical and Strategic Control: The Limits of Capacity-Based Measures for Revealing Unsafe Visual Sampling Mod…
2011
The control theory of driving suggests that driver distraction can be analyzed as a breakdown of control at three levels. Common approach for analyzing distraction experimentally is to utilize capacity-based measures to assess distraction at the level of operational control. Three driving simulation experiments with 61 participants were organized to evaluate which kind of measures could be used to analyze drivers' tactical visual sampling models and the related effects of distraction while searching textual information on in-car display. The effects of two different text types were evaluated. The utilized capacity-based measures seemed to be insufficient for revealing participants' tactical…
A Cooperative Coevolution Framework for Parallel Learning to Rank
2015
We propose CCRank, the first parallel framework for learning to rank based on evolutionary algorithms (EA), aiming to significantly improve learning efficiency while maintaining accuracy. CCRank is based on cooperative coevolution (CC), a divide-and-conquer framework that has demonstrated high promise in function optimization for problems with large search space and complex structures. Moreover, CC naturally allows parallelization of sub-solutions to the decomposed sub-problems, which can substantially boost learning efficiency. With CCRank, we investigate parallel CC in the context of learning to rank. We implement CCRank with three EA-based learning to rank algorithms for demonstration. E…
Learnings from the Finnish Game Industry
2016
The motivation behind our research was the rapid growth and business wins of world-class Finnish game companies, like Supercell, as well as the success of other game companies in Finland. In particular, Supercell's growth is something that has not been heard of before and this raised the interest to research what game companies have been doing right. Supercell is not the only Finnish success. Rovio is also well known and has the roots for success from few years before. There are also other game companies in Finland that have succeeded and this motivated us to investigate what is happening behind the game industry and what could be learned from there that could be applied to other software i…
The Quest for Underpinning Theory of Enterprise Architecture - General Systems Theory
2017
Enterprise architecture originates from the 1980’s. It emerged among ICT practitioners to solve complex problems related to information systems. Currently EA is also utilised to solve business problems, although the focus is still in ICT and its alignment with business. EA can be defined as a description of the current and future states of the enterprise, and as a change between these states to meet stakeholder’s goals. Despite its popularity and 30 years of age, the literature review conducted on top information and management science journals revealed that EA is still lacking the sound theoretical foundation. In this conceptual paper, we propose General Systems Theory (GST) for underpinni…