Viewing the Steklov eigenvalues of the Laplace operator as critical Neumann eigenvalues

We consider the Steklov eigenvalues of the Laplace operator as limiting Neumann eigenvalues in a problem of boundary mass concentration. We discuss the asymptotic behavior of the Neumann eigenvalues in a ball and we deduce that the Steklov eigenvalues minimize the Neumann eigenvalues. Moreover, we study the dependence of the eigenvalues of the Steklov problem upon perturbation of the mass density and show that the Steklov eigenvalues violates a maximum principle in spectral optimization problems.Comment: This is a preprint version of a paper that will appear in the Proceedings of the 9th ISAAC Congress, Krak\'ow 201

Wave simulation for the design of an innovative quay wall: the case of Vlorë Harbour

Sea states and environmental conditions are basic data for the design of marine structures. Hindcasted wave data have been applied here with the aim of identifying the proper design conditions for an innovative quay wall concept. In this paper, the results of a computational fluid dynamics model are used to optimise the new absorbing quay wall of Vlorë Harbour (Republic of Albania) and define the design loads under extreme wave conditions. The design wave states at the harbour entrance have been estimated analysing 31 years of hindcasted wave data simulated through the application of WaveWatch III. Due to the particular geography and topography of the Bay of Vlorë, wave conditions generated from the north-west are transferred to the harbour entrance with the application of a 2-D spectral wave module, whereas southern wave states, which are also the most critical for the port structures, are defined by means of a wave generation model, according to the available wind measurements. Finally, the identified extreme events have been used, through the NewWave approach, as boundary conditions for the numerical analysis of the interaction between the quay wall and the extreme events. The results show that the proposed method, based on numerical modelling at different scales from macro to meso and to micro, allows for the identification of the best site-specific solutions, also for a location devoid of any wave measurement. In this light, the objectives of the paper are two-fold. First, they show the application of sea condition estimations through the use of wave hindcasted data in order to properly define the design wave conditions for a new harbour structure. Second, they present a new approach for investigating an innovative absorbing quay wall based on CFD modelling and the NewWave theory

Gradient based sequential Markov chain Monte Carlo for multitarget tracking with correlated measurements

Measurements in wireless sensor networks (WSNs) are often correlated both in space and in time. This paper focuses on tracking multiple targets in WSNs by taking into consideration these measurement correlations. A sequential Markov Chain Monte Carlo (SMCMC) approach is proposed in which a Metropolis within Gibbs refinement step and a likelihood gradient proposal are introduced. This SMCMC filter is applied to case studies with cellular network received signal strength data in which the shadowing component correlations in space and time are estimated. The efficiency of the SMCMC approach compared to particle filtering, as well as the gradient proposal compared to a basic prior proposal, are demonstrated through numerical simulations. The accuracy improvement with the gradient-based SMCMC is above 90% when using a low number of particles. Thanks to its sequential nature, the proposed approach can be applied to various WSN applications, including traffic mobility monitoring and prediction

Sequential Markov Chain Monte Carlo for multi-target tracking with correlated RSS measurements

In this paper, we present a Bayesian approach to accurately track multiple objects based on Received Signal Strength (RSS) measurements. This work shows that taking into account the spatial correlations of the observations caused by the random shadowing effect can induce significant tracking performance improvements, especially in very noisy scenarios. Additionally, the superiority of the proposed Sequential Markov Chain Monte Carlo (SMCMC) method over the more common Sequential Importance Resampling (SIR) technique is empirically demonstrated through numerical simulations in which multiple targets have to be tracked

Spectral analysis of the biharmonic operator subject to Neumann boundary conditions on dumbbell domains

We consider the biharmonic operator subject to homogeneous boundary conditions of Neumann type on a planar dumbbell domain which consists of two disjoint domains connected by a thin channel. We analyse the spectral behaviour of the operator, characterizing the limit of the eigenvalues and of the eigenprojections as the thickness of the channel goes to zero. In applications to linear elasticity, the fourth order operator under consideration is related to the deformation of a free elastic plate, a part of which shrinks to a segment. In contrast to what happens with the classical second order case, it turns out that the limiting equation is here distorted by a strange factor depending on a parameter which plays the role of the Poisson coefficient of the represented plate.Comment: To appear in "Integral Equations and Operator Theory

High-Voltage Energy Harvesting and Storage System for Internet of Things Indoor Application

On the path toward independence from fossil fuels, solar energy is the mostpromising solution, but it needs a robust and reliable storage system to face itsintrinsicfluctuations due to location, day cycle, and weather. The integrationbetween energy harvesting and storage (H&S) technologies is a must toward cleanenergy production, and it becomes even more appealing considering the possi-bility of producing electricity not only from direct sunlight but also from diffuselight and indoor illumination. Herein, a dye-sensitized solar module (DSSM)developed to harvest indoor illumination and directly store it into an electricaldouble-layer capacitor (EDLC) is presented. Five series-connected dye-sensitizedsolar cells are fabricated on the same substrate and the module is integrated with ahigh-voltage EDLC. The integrated device is characterized under indoor lightsources such as light emitting diodes andfluorescent lamps. The results show oneof the highest efficiencies ever reported for a high-voltage DSSM under indoorillumination (16.27%), the largest voltage window ever reported for an indoor H&Sdevice based on DSSM and EDLC—up to 3 V—and an overall photoelectricconversion and storage efficiency of 9.73% under indoor illumination

CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water

publisher: Elsevier articletitle: CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water journaltitle: Applied Ocean Research articlelink: http://dx.doi.org/10.1016/j.apor.2016.10.002 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved

Steklov-type eigenvalues associated with best Sobolev trace constants: domain perturbation and overdetermined systems

We consider a variant of the classic Steklov eigenvalue problem, which arises in the study of the best trace constant for functions in Sobolev space. We prove that the elementary symmetric functions of the eigenvalues depend real-analytically upon variation of the underlying domain and we compute the corresponding Hadamard-type formulas for the shape derivatives. We also consider isovolumetric and isoperimetric domain perturbations and we characterize the corresponding critical domains in terms of appropriate overdetermined systems. Finally, we prove that balls are critical domains for the elementary symmetric functions of the eigenvalues subject to volume or perimeter constraint

3D Reconstruction and Presentation of Cultural Heritage: AR and VR Experiences at the Museo d’Arte Orientale di Torino

For years, virtual reconstruction in the figurative arts, and sculpture, in particular, has been developing and consolidating. The workflow from the acquisition to three-dimensional modelling and to the integration of missing parts, has been optimized through processes entirely implemented in the digital dimension. The most recent developments in augmented reality and virtual reality technologies, together with the possibility of using low-cost and widely available devices, have made it possible to establish new links between the real and the virtual. The experiences presented in this paper comes up within the agreement between the Politecnico di Torino and the Museo d’Arte Orientale (MAO). The workflow set up for this research involves: structure from motion (SfM) survey, 3D modelling, and 3D philological reconstruction, then develops a proposal to implement augmented and virtual reality experiences aimed at the communication and fruition of the exhibits. The case study concerns two Japanese statues, and proposes their visualisation with the respective weapons virtually reconstructed, and through VR, involving the reconstruction of the interior space of a temple recognised as philologically compatible with the location of the statues within a statuary complex