Search results for " modelling"
showing 10 items of 1055 documents
A three-dimensional boundary element model for the analysis of polycrystalline materials at the microscale
2012
A three-dimensional multi-domain anisotropic boundary element formulation is presented for the analysis of polycrystalline microstructures. The formulation is naturally expressed in terms of intergranular displacements and tractions that play an important role in polycrystalline micromechanics, micro-damage and micro-cracking. The artificial morphology is generated by Hardcore Voronoi tessellation, which embodies the main statistical features of polycrystalline microstructures. Each crystal is modeled as an anisotropic elastic region and the integrity of the aggregate is restored by enforcing interface continuity and equilibrium between contiguous grains. The developed technique has been ap…
A Machine Learning Model to Predict Intravenous Immunoglobulin-Resistant Kawasaki Disease Patients: A Retrospective Study Based on the Chongqing Popu…
2021
Objective: We explored the risk factors for intravenous immunoglobulin (IVIG) resistance in children with Kawasaki disease (KD) and constructed a prediction model based on machine learning algorithms.Methods: A retrospective study including 1,398 KD patients hospitalized in 7 affiliated hospitals of Chongqing Medical University from January 2015 to August 2020 was conducted. All patients were divided into IVIG-responsive and IVIG-resistant groups, which were randomly divided into training and validation sets. The independent risk factors were determined using logistic regression analysis. Logistic regression nomograms, support vector machine (SVM), XGBoost and LightGBM prediction models wer…
The positioning system of the ANTARES Neutrino Telescope
2012
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning sys…
Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems
2011
The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Rea…
Magnetic Stochastic Resonance in systems described by Dynamic Preisach Model
2008
Stochastic resonance (SR) is generally considered as an enhancement of the system response for certain finite values of the noise strength. In particular the signal to noise ratio (SNR) and the signal amplification show a maximum as a function of the noise intensity. This effect has been experimentally observed in many physical systems and also in magnetic systems. However, as far as magnetic systems are concerned, the dynamic features of the systems have been neglected and it has been assumed that the typical relaxation time is negligible. However this is clearly a rough approximation. In order to clarify this relation, in this paper we numerically study magnetic stochastic resonance in se…
Prosthetic modelling and simulation
2020
Abstract Modelling of physical systems can be divided into two categories: physical and mathematical modelling. Physical modelling is a process in which we construct tangible scale models that look very much like the real system. In the past century, consider the animal models that have significantly influenced the development of disease treatment and artificial joints. However, scale models require a great deal of time and resources to develop and there are limits to what can be learned from them. Mathematical or behavioural modelling is a more abstract system used for studying a research question that does not necessarily lend itself to physical modelling. In these models, the system is s…
Biological nitrogen and phosphorus removal in membrane bioreactors: model development and parameter estimation
2012
Membrane bioreactors (MBR) are being increasingly used for wastewater treatment. Mathematical modeling of MBR systems plays a key role in order to better explain their characteristics. Several MBR models have been presented in the literature focusing on different aspects: biological models, models which include soluble microbial products (SMP), physical models able to describe the membrane fouling and integrated models which couple the SMP models with the physical models. However, only a few integrated models have been developed which take into account the relationships between membrane fouling and biological processes. With respect to biological phosphorus removal in MBR systems, due to th…
Designing dynamic performance management systems to foster SME competitiveness according to a sustainable development perspective: empirical evidence…
2015
The role of performance management (PM) systems has become crucial for steering small-medium enterprises (SMEs) to successfully compete during the ongoing critical economic transition. To improve decision-maker strategic learning processes, traditional PM frameworks need to be combined with system dynamics (SD) modelling. This paper shows how to design and use a dynamic performance management (DPM) approach to assess and support SMEs competitiveness according to a sustainable development perspective. The emerging framework is applied to a real case of an Italian small business to analyse the empirical effectiveness of the approach hereby suggested.
Supporting start-up business model design through system dynamics modelling
2017
Purpose The purpose of this paper is to explore how system dynamics (SD) modelling can provide a methodological support to business model (BM) design with the intent to better communicate business strategy and manage performance. Design/methodology/approach After a literature review of the field and an analysis of the strengths and limitations of conventional BM frameworks, the paper illustrates and discusses an approach that combines such a framework with SD modelling. A single-case study design was selected to explore the implications and limitations of using this combined approach to business modelling. Findings The methodological support provided by SD to BM design may effectively impr…
Combining system dynamics modelling and management control systems to support strategic learning processes in SMEs: a Dynamic Performance Management …
2015
Traditional management control systems, mainly centred on accounting-based measures, are widely recognized as useful tools to support Small and Medium Enterprises (SMEs) managers and entrepreneurs in steering business development. However, due to the increasing turbulence and dynamic complexity that characterize today’s competitive arenas, such systems need to be combined with simulation-based methodologies in order to improve entrepreneurial learning processes and, as a result, better detect possible crisis symptoms and weak signals of change—emerging from the business environment—to promptly react. Therefore, the aim of this paper is to show how a combination of traditional management con…