Search results for "Complex system"
showing 10 items of 226 documents
The influence of the dynamics of ionic multiplets onto electronic transport properties of heavy-fermion systems: a semi-phenomenological approach
2001
We present calculations of the electronic transport properties of heavy-fermion systems within a semi-phenomenological approach to the dynamical mean field theory. In this approach the dynamics of the Hund's rules 4f (5f )-ionic multiplet split in a crystalline environment is taken into account. Within the scope of this calculation we use the linear response theory to reproduce qualitative features of the temperature-dependent resistivity and hall conductivity, the magneto-resistivity and the thermoelectric power typical for heavy-fermion systems. The model calculations are directly compared with experimental results on CeCu2Si2.
Emery vs. Hubbard model for cuprate superconductors: A composite operator method study
2013
Within the Composite Operator Method (COM), we report the solution of the Emery model (also known as p-d or three band model), which is relevant for the cuprate high-Tc superconduc- tors. We also discuss the relevance of the often-neglected direct oxygen-oxygen hopping for a more accurate, sometimes unique, description of this class of materials. The benchmark of the solution is performed by comparing our results with the available quantum Monte Carlo ones. Both single- particle and thermodynamic properties of the model are studied in detail. Our solution features a metal-insulator transition at half filling. The resulting metal-insulator phase diagram agrees qual- itatively very well with …
Remarks on quantum groups
1991
We give a Poisson-bracket realization of SL q (2) in the phase space ℝ2. We then discuss the physical meaning of such a realization in terms of a modified (regularized) toy model, the nonregularized version of which is due to Klauder. Some general remarks and suggestions are also presented in this Letter.
DECISION-MAKING MODELS FOR PREDICTIVE MAINTENANCE SERVICE SUPPORT SYSTEMS
2023
Nell'era digitale, la tecnologia è in continua evoluzione, con enormi progressi nell'automazione che consentono una gestione della manutenzione più efficiente ed economica. Le tecnologie digitali stanno convergendo e avanzando insieme alle industrie, determinando progressi significativi nella gestione della manutenzione. La tradizionale strategia di manutenzione preventiva gestita dall'uomo lascia progressivamente spazio alla manutenzione predittiva, che rappresenta un’ottima opportunità per migliorare significativamente la pianificazione della manutenzione del sistema, in particolare per i sistemi più complessi e dal significativo valore monetario. Tuttavia, l’implementazione di tecniche d…
Sport arbitration as an emergent process in a complex system: Decision-making variability is a marker of expertise in national-level football referees
2020
This study examined the experiential knowledge of eight Australian national-level football referees (3.2 yrs mean national-level experience) about the notion of consistent decision-making during competitive matches. Using a grounded theory approach, the analysis revealed that participants view “consistency” as context-dependent, rather than a rigid process of uniformly responding to isolated foul-play transgressions with putatively correct responses. Our results present two key conceptual abstractions—”referential and game dependent” and “purpose and context”—as a framework for understanding referee decision-making consistency. Results evidence that in higher level referees, consistent deci…
Modeling the escalation/de-escalation of response operation levels in disaster response networks using hierarchical Colored Petri Nets (CPN) approach
2018
In emergency situations, the first responders need to act promptly to situations, while the disaster management authorities' response might not be at the same speed. Delays by disaster management authorities had a direct impact on response operations led response teams to the shift away from command and control structures to net-centric ones. This paper is part of a study to examine patterns of emerging organizational relations and coordination structures in disaster response operations. Understanding coordination patterns in disaster chaos can help to integrate those patterns in the planning and execution in the modern disaster management operations. We use dynamic modeling methods to anal…
Holonic Handling the Unexpected in Project Management
2017
Abstract Risk assessment is one the key activities of any project. The unexpected situations can have catastrophic consequences. Risk assessment tries to estimate to potential known unknowns, but there is no guarantee to foresee all circumstances around a project. In this situation the project team must be adaptive and find solutions by cooperation, creativity and abductive reasoning. In the paper we tried to analyse on what extent a project and a project team can be handled as a complex adaptive system. More precisely, how the scientific and practical achievements of the theory of complex adaptive systems (CAS) can be used in project management. More exactly, we analyse the applicability o…
Boundary Regularity for the Porous Medium Equation
2018
We study the boundary regularity of solutions to the porous medium equation $u_t = \Delta u^m$ in the degenerate range $m>1$. In particular, we show that in cylinders the Dirichlet problem with positive continuous boundary data on the parabolic boundary has a solution which attains the boundary values, provided that the spatial domain satisfies the elliptic Wiener criterion. This condition is known to be optimal, and it is a consequence of our main theorem which establishes a barrier characterization of regular boundary points for general -- not necessarily cylindrical -- domains in ${\bf R}^{n+1}$. One of our fundamental tools is a new strict comparison principle between sub- and superpara…
Parametric self-trapping in the presence of randomized quasi phase matching
2010
We report on experimental evidence of parametric spatial solitons in a quadratic crystal with randomized periodic ferroelectric poling. Two-color self-focusing via quadratic cascading overcomes the diffractive nature of both fundamental and frequency-doubled beams.
From time series to complex networks: the visibility graph
2008
In this work we present a simple and fast computational method, the visibility algorithm , that converts a time series into a graph. The constructed graph inherits several properties of the series in its structure. Thereby, periodic series convert into regular graphs, and random series do so into random graphs. Moreover, fractal series convert into scale-free networks, enhancing the fact that power law degree distributions are related to fractality, something highly discussed recently. Some remarkable examples and analytical tools are outlined to test the method's reliability. Many different measures, recently developed in the complex network theory, could by means of this new approach cha…