Search results for "Continuous"

High-fidelity analysis of multilayered shells with cut-outs via the discontinuous Galerkin method

2021

Abstract A novel numerical method for the analysis of multilayered shells with cut-outs is presented. In the proposed approach, the shell geometry is represented via either analytical functions or NURBS parametrizations , while generally-shaped cut-outs are defined implicitly within the shell modelling domain via a level set function . The multilayered shell problem is addressed via the Equivalent-Single-Layer approach whereby high-order polynomial functions are employed to approximate the covariant components of the displacement field throughout the shell thickness. The shell governing equations are then derived from the Principle of Virtual Displacements of three-dimensional elasticity an…

On Fuzzy Stochastic Integral Equations—A Martingale Problem Approach

2011

In the paper we consider fuzzy stochastic integral equations using the methods of stochastic inclusions. The idea is to consider an associated martingale problem and its solutions in order to obtain a solution to the fuzzy stochastic equation.

Non-Contact Measurement of River Surface Velocity and Discharge Estimation with a Low-Cost Doppler Radar Sensor

2020

River discharge is an important variable to measure in order to predict droughts and flood occurrences. Once the cross-sectional geometry of the river is known, discharge can be inferred from water level and surface flow velocity measurements. Since river discharges are of particular interest during extreme weather events, when river sites cannot be safely accessed, noncontact sensing technologies are particularly appealing. To this purpose, this work proposes a prototype of a low-cost continuous wave (CW) Doppler radar sensor, which is able to monitor the surface flow velocity of rivers. The prototype is tested at two gauged sites in central Italy, along the Tiber River. The surface flow v…

Diagnosis of Incipient Bearing Faults using Convolutional Neural Networks

2019

The majority of faults occurring in rotating electrical machinery is attributed to bearings. To reduce downtime, it is desired to apply various diagnostic methods so that bearing degradation can be detected in good time prior to a complete failure. The work presented in this paper utilizes a data-driven machine learning approach based on convolutional neural networks (CNNs) in order to diagnose different types of bearing faults. A one-dimensional CNN is trained on vibration signals and compared to a two-dimensional CNN trained in time-frequency domain using continuous wavelet transform (CWT). The proposed method is demonstrated on data collected from run-to-failure tests.The results show th…

Quantized Dissensus in Networks of Agents subject to Death and Duplication

2012

Dissensus is a modeling framework for networks of dynamic agents in competition for scarce resources. Originally inspired by biological cells behaviors, it fits also marketing, finance and many other application areas. Competition is often unstable in the sense that strong agents, those having access to large resources, gain more and more resources at the expense of weak agents. Thus, strong agents duplicate when reaching a critical amount of resources, whereas weak agents die when loosing all their resources. To capture all these phenomena we introduce systems with a discrete time gossip and unstable state dynamics interrupted by discrete events affecting the network topology. Invariancy o…

A wavelet-based tool for studying non-periodicity

2010

This paper presents a new numerical approach to the study of non-periodicity in signals, which can complement the maximal Lyapunov exponent method for determining chaos transitions of a given dynamical system. The proposed technique is based on the continuous wavelet transform and the wavelet multiresolution analysis. A new parameter, the \textit{scale index}, is introduced and interpreted as a measure of the degree of the signal's non-periodicity. This methodology is successfully applied to three classical dynamical systems: the Bonhoeffer-van der Pol oscillator, the logistic map, and the Henon map.

Flow photochemistry of azosulfones: application of “Sunflow” reactors

2018

The Legacy and the Tyranny of Time: Exit and Re-Entry of Sovereigns to International Capital Markets

2018

We use a novel continuous-time Weibull model (without and) with a change-point in the duration dependence parameter to investigate the duration of the exit and re-entry of sovereigns to international capital markets. Relying on annual data for a large panel of countries over the period 1970-2011, we find that, as the reputation of debtor countries as good (bad) borrowers solidifies over time, those episodes are more likely to end - i.e. the "legacy of time". Debtor countries can take advantage of the "benefit of doubt" of creditors during short exit spells. However, when exits are long and the reputation as a bad borrower emerges, no more "complacency" makes it more difficult for them to bo…

What Geographical Concentration of Industries in the Tunisian Sahel? Empirical Evidence Using Distance‐Based Measures

2020

International audience; This paper examines the location patterns of manufacturing industries within the most developed regions of Tunisia, the Sahel. We use detailed micro-geographic data and the distance-based approach of Duranton and Overman. While the textile industry shows a high degree of geographical concentration, the high-tech industries are also among the most concentrated, meaning that the Tunisian Sahel gathers a specialised pool in these industries. We further analyse the location patterns of manufacturing sub-sectors: totally and partially exporting plants and domestic, mixed and foreign plants and show that totally exporting plants and foreign and mixed plants exhibit strong …

Nonlinear dynamics of interest rate and inflation

2004

According to several empirical studies, US inflation and nominal interest rates, as well as the real interest rate, can be described as unit root processes. These results imply that nominal interest rates and expected inflation do not move one-for-one in the long run, which is not consistent with the theoretical models. In this paper we introduce a nonlinear bivariate mixture autoregressive model that seems to fit quarterly US data (1952 Q1 – 2000 Q2) reasonably well. It is found that the three-month treasury bill rate and inflation share a common nonlinear component that explains a large part of their persistence. The real interest rate is devoid of this component, indicating one-for-one m…