Observability of Path Loss Parameters in WLAN-Based Simultaneous Localization and Mapping

Indoor positioning by means of received signal strengths has been gathering much interest since the massive presence of wireless local area networks (WLANs) in buildings. Theoretical approaches rely on the perfect knowledge of the APs' positions and propagation conditions; since this is unrealistic in real world, we estimate such knowledge as well as the building map from data by applying Simultaneous Localization and Mapping (SLAM). In this paper we address the joint estimation of the path loss parameters, namely the transmitted power and the path loss exponent, this latter being usually approximated in the literature by the free space value. We provide examples that show the relevance of estimating both parameters and analyze observability issues from the point of view of estimation theory. The integration of the parameter estimation in a WLAN based SLAM algorithm - WiSLAM - has been carried out and the results are discussed

A Multiphase First Order Model for Non-Equilibrium Sand Erosion, Transport and Sedimentation

Three phenomena are involved in sand movement: erosion, wind transport, and sedimentation. This paper presents a comprehensive easy-to-use multiphase model that include all three aspects with a particular attention to situations in which erosion due to wind shear and sedimentation due to gravity are not in equilibrium. The interest is related to the fact that these are the situations leading to a change of profile of the sand bed

Quantum discord in a spin system with symmetry breaking

We analyze the quantum discord Q throughout the low-temperature phase diagram of the quantum XY model in transverse field. We first focus on the T=0 order-disorder quantum phase transition both in the symmetric ground state and in the symmetry broken one. Besides it, we highlight how Q displays clear anomalies also at a non critical value of the control parameter inside the ordered phase, where the ground state is completely factorized. We evidence how the phenomenon is in fact of collective nature and displays universal features. We also study Q at finite temperature. We show that, close to the quantum phase transition, Q exhibits quantum-classical crossover of the system with universal scaling behavior. We evidence a non trivial pattern of thermal correlations resulting from the factorization phenomenon.Comment: 9 pages, 9 figure, Contribution to the Festschrift volume in honour of Vladimir Korepi

Global approach for fitting 2D interferometric data

The present paper describes a fitting procedure capable of providing a smooth approximation of experimental data distributed on a bi-dimensional domain, e.g. the typical output of an interferometric technique. The procedure is based on the optimization of an analytical model defined on the whole domain by the B-spline formulation. In the paper rectangular, circular and polygonal convex domains are considered in details, but, according to the need of the operating conditions, the procedure can be extended to domains of different shapes. The proposed procedure was initially calibrated by an analytical case study: a thin square plate simply supported along the edges and loaded by a uniform pressure. Subsequently, by the operative parameters defined by the analyses carried out on the analytic data, the fitting procedure was applied on experimental data obtained by phase shifting speckle interferometry

combined use of confocal microscopy and dic for 3d displacement vector measurement

Abstract In the present paper the author describes the potential offered by the combined use of the Confocal Microscopy (CM) and Digital Image Correlation (DIC) to resolve the whole displacement vector in full-field fashion and with nanometric accuracy. By means of two different configurations of the same portion of the area under investigation, the surface profile retrieved at microscopic level by the CM functioned as a carrier for the DIC algorithm, both for a polished surface and an engineering standard roughness. The in-plane displacement components obtained by DIC were then used to extract the out-of-plane component from the profile information. After describing all steps that are necessary for applying the procedure, preliminary results of an indentation tests carried out on a polished steel specimen are reported and discussed

Full-field measurement with nanometric accuracy of 3D superficial displacements by digital profile correlation: A powerful tool for mechanics of materials

In recent decades, technological innovations have prompted the development of pioneering materials that attempt to satisfy new and forthcoming needs. The innovation in these materials is usually from their peculiar properties, which in many cases make them uniquely appropriate for a specific application. In this context, the development of innovative measurement techniques can provide more comprehensive understanding and knowledge of these materials' properties, often non-conventional and not easily retrieved by standard procedures. In order to obtain a full-field 3D displacement vector of a surface under investigation, the author proposes the combination of two well-known measurement techniques: the Confocal Microscopy (CM) and the two-dimensional Digital Image Correlation (2D-DIC). Specifically, CM has demonstrated its ability to successfully attain microscopic topography on a highly finished surface with sub-micrometric roughness, and such a technique could be used as a carrier to successfully apply the 2D-DIC algorithm. By this approach, it is not difficult to reach an accuracy of a few nanometers on the displacement measurement. The feasibility of the procedure proposed herein was demonstrated by two case studies: a tensile test of a Ni-alloy edge crack specimen, and a hardness test carried out on a thick AISI 1040 disk. Keywords: Digital image correlation, Profilometry, Full-field measurement, Confocal microscopy, Mechanics of material

Finite-discrete element modelling of masonry infill walls subjected to out-of-plane loads

In this paper, the out-of-plane response of infill walls is investigated by means of non-linear monotonic (push-over) analyses through a combined finite and discrete modelling approach. The model accounts for material deformability, crack formation, sliding, separa-tion and formation of new contacts. Masonry units are modelled as finite elements, and differ-ent material models are assumed for the masonry. Contact between masonry units, and between masonry and frame elements is modelled by means of interfaces, which permit tan-gential motion with frictional sliding. Frame elements are modelled by means of a linear-elastic material. The results of the numerical analyses are compared with those of experimen-tal tests available in the literature. The advantages and disadvantages of the adopted model-ling strategy are investigated

Outcomes in the emergency endovascular repair of blunt thoracic aortic injuries

Abstract Thoracic aorta blunt injury (BAI) is a highly lethal lesion. A large number of victims die before obtaining emergency care. Thoracic endovascular aneurysm repair (TEVAR) is a less invasive method compared with open surgery and may change protocols for BAI treatment. This retrospective study was developed to evaluate the potential issues about thoracic endografting in the management of these patients. Twenty-seven patients with a BAI underwent aortic stent grafting. Intervention was preceded by the treatment of more urgent associated lesions in nine cases. In-hospital mortality was 7.4%. No paraplegia or ischemic complications developed because of the coverage of the left subclavian artery. In one case (3.2%), a type I endoleak was detected, proximal endograft infolding in two cases (7.4%) and endograft distal migration in further two cases were detected during follow-up (6-110 months). Thoracic endovascular aneurysm repair of BAI showed encouraging results in terms of perioperative mortality and morbidity. Concerns still remain about the potential mid- and long-term complications in younger patients