Search results for " flows"
showing 10 items of 110 documents
Chances and Challenges of Computational Data Gathering and Analysis
2015
Digital and social media and large available data-sets generate various new possibilities and challenges for conducting research focused on perpetually developing online news ecosystems. This paper presents a novel computational technique for gathering and processing large quantities of data from Facebook. We demonstrate how to use this technique for detecting and analysing issue-attention cycles and news flows in Facebook groups and pages. Although the paper concentrates on a Finnish Facebook group as a case study, the demonstrated method can be used for gathering and analysing large sets of data from various social network sites and national contexts. The paper also discusses Facebook pla…
On the Relevance of Agency Conflicts in SME Debt Maturity Structure
2015
Previous theoretical research asserts that an optimal policy of debt maturity structure mitigates the various agency conflicts that arise through debt contracts. We test this hypothesis on Small and Medium-Sized Enterprises (SMEs), which are very sensitive to agency problems. Such problems mainly arise between owners and debt providers, due to SMEs recording high growth and having few fixed assets and informational asymmetry. We provide evidence on the relevant effect of underinvestment, asset substitution, and overinvestment problems on SME debt structure. Results appear to be robust to both the endogeneity problem of explanatory variables and the censored dependent variable.
Investigating Limits in Exploiting Assembled Landslide Inventories for Calibrating Regional Susceptibility Models: A Test in Volcanic Areas of El Sal…
2022
This research is focused on the evaluation of the reliability of regional landslide susceptibility models obtained by exploiting inhomogeneous (for quality, resolution and/or triggering related type and intensity) collected inventories for calibration. At a large-scale glance, merging more inventories can result in well-performing models hiding potential strong predictive deficiencies. An example of the limits that such kinds of models can display is given by a landslide susceptibility study, which was carried out for a large sector of the coastal area of El Salvador, where an apparently well-performing regional model (AUC = 0.87) was obtained by regressing a dataset through multivariate ad…
A simple procedure to improve the pressure evaluation in hydrodynamic context using the SPH
2009
In literature, it is well know that the Smoothed Particle Hydrodynamics method can be affected by numerical noise on the pressure field when dealing with liquids. This can be highly dangerous when an SPH code is dynamically coupled with a structural solver. In this work a simple procedure is proposed to improve the computation of the pressure distribution in the dynamics of liquids. Such a procedure is based on the use of a density diffusion term in the equation for the mass conservation. This diffusion is a pure numerical effect, similar to the well known artificial viscosity originally proposed in SPH method to smooth out the shock discontinuities. As the artificial viscosity, the density…
Large Eddy Simulations of Rough Turbulent Channel Flows Bounded by Irregular Roughness: Advances Toward a Universal Roughness Correlation
2020
The downward shift of the mean velocity profile in the logarithmic region, known as roughness function, $$\Delta U^+$$ , is the major macroscopic effect of roughness in wall bounded flows. This speed decrease, which is strictly linked to the friction Reynolds number and the geometrical properties which define the roughness pattern such as roughness height, density, shape parameters, has been deeply investigated in the past decades. Among the geometrical parameters, the effective slope (ES) seems to be suitable to estimate the roughness function at fixed friction Reynolds number, Re $$_{\tau }$$ . In the present work, the effects of several geometrical parameters on the roughness function, i…
Large eddy simulations on the effect of the irregular roughness shape on turbulent channel flows
2019
Abstract Large Eddy Simulations (LES) are carried out to investigate on the mean flow in turbulent channel flows over irregular rough surfaces. Here the attention is focused to selectively investigate on the effect induced by crests or cavities of the roughness. The irregular shape is generated through the super-imposition of sinusoidal functions having random amplitude and four different wave-lengths. The irregular roughness profile is reproduced along the spanwise direction in order to obtain a 2D rough shape. The analysis of the mean velocity profiles shows that roughness crests induce higher effect in the outer-region whereas roughness cavities cause the highest effects in the inner-reg…
Il Paradigma della Città Fluida
2013
Nella recente crisi globale i poderosi flussi di capitali finanziari, sociali e relazionali che hanno alimentato la riqualificazione urbana nel corso degli ultimi quindici anni non sono più disponibili ad essere intercettati in maniera indiscriminata così come è stato possibile fino a qualche anno fa. Nell'era della crisi strutturale le città più dinamiche non sono più quelle in grado di attrarre progetti urbani iconici ed investitori spinti dal mercato immobiliare o dalla redditività delle attività ricreative, ma quelle città che, a partire dalle loro profonde e diversificate risorse culturali, saranno capaci di attuare una vera e propria “metamorfosi” per usarle come base per la creazione…
ASSESSMENT OF CORRUPTION EFFECT ON FOREIGN INVESTMENT FLOWS
2011
The purpose of the present paper is to investigate the impact of corruption on foreign direct investment (FDI) flows. Using data from the International Monetary Fund, Transparency International and United Nations conference about commerce and development data bases a cross-section econometric model was estimated to evaluate in which way and how strong corruption influence FDI inflows. Econometric modelling covers the period from year 2000 to 2007 and the data about 82 world countries that constitute more than 500 records. The main conclusion of the paper is that corruption has a negative and significant impact on the foreign direct investment inflows. Thus, changes in the level of corruptio…
BVP ir skolinimo elgsena : empiriniai Baltijos šalių ekonomikos požymiai
2021
Darnus ekonominis vystymasis remiasi stabilia ir palankia verslo aplinka, kuri skatina organizacijų konkurencingumą. Komerciniai bankai palengvina kapitalo judėjimą iš mažiau efektyvių ekonomikos sektorių į labiau konkurencingas ekonomikos šakas. Šio tyrimo tikslas – išanalizuoti Baltijos šalių BVP dinamiką 2005-2010 metais ir patikrinti BVP koreliavimą su vietinių komercinių bankų išduotų paskolų verslui skaičiumi. Tyrimo rezultatai parodė, kad yra požymių, jog egzistuoja abipusė priklausomybė tarp BVP veiksnių ir išduotų paskolų, tai savo ruožtu sudaro pagrindą formuoti pasiūlymus, kaip gaivinti Baltijos šalių ekonomiką. Šešiose pramonės šakose atliktas Granger BVP ir skolinimo priežastin…
Large eddy simulation of inertial particles dispersion in a turbulent gas-particle channel flow bounded by rough walls
2020
The purpose of this paper is to understand the capability and consistency of large eddy simulation (LES) in Eulerian–Lagrangian studies aimed at predicting inertial particle dispersion in turbulent wall-bounded flows, in the absence of ad hoc closure models in the Lagrangian equations of particle motion. The degree of improvement granted by LES models is object of debate, in terms of both accurate prediction of particle accumulation and local particle segregation; therefore, we assessed the accuracy in the prediction of the particle velocity statistics by comparison against direct numerical simulation (DNS) of a finer computational mesh, under both one-way and two-way coupling regimes. We p…