Effect of Martian Suspended Dust on Albedo Measurements from the MGS-TES Data

Suspended dust on Mars influences albedo measurements by orbiting instruments, but not necessary the real surface albedo. The aim of this study is to characterize the role of suspended aerosols on albedo measurement by remote sensing instruments

An Updating Method for Finite Element Models of Flexible-Link Mechanisms Based on an Equivalent Rigid-Link System

This paper proposes a comprehensive methodology to update dynamic models of flexible-link mechanisms (FLMs) modeled through ordinary differential equations. The aim is to correct mass, stiffness, and damping matrices of dynamic models, usually based on nominal and uncertain parameters, to accurately represent the main vibrational modes within the bandwidth of interest. Indeed, the availability of accurate models is a fundamental step for the synthesis of effective controllers, state observers, and optimized motion profiles, as those employed in modern control schemes. The method takes advantage of the system dynamic model formulated through finite elements and through the representation of the total motion as the sum of a large rigid-body motion and the elastic deformation. Model updating is not straightforward since the resulting model is nonlinear and its coordinates cannot be directly measured. Hence, the nonlinear model is linearized about an equilibrium point to compute the eigenstructure and to compare it with the results of experimental modal analysis. Once consistency between the model coordinates and the experimental data is obtained through a suitable transformation, model updating has been performed solving a constrained convex optimization problem. Constraints also include results from static tests. Some tools to improve the problem conditioning are also proposed in the formulation adopted, to handle large dimensional models and achieve reliable results. The method has been experimentally applied to a challenging system: a planar six-bar linkage manipulator. The results prove their capability to improve the model accuracy in terms of eigenfrequencies and mode shapes

digital surveys and 3d reconstructions for augmented accessibility of archaeological heritage

Abstract. This paper presents part of the results of a larger research project that focused on the surveying and documenting of Roman theatres and amphitheatres in the Campania region as well as the testing of a virtual fruition system for the digital reconstruction of a case study: the Roman theatre of Benevento. The work was carried out by the research group at the Interdepartmental Urban/Eco Research Centre of the University of Naples Federico II in collaboration with Spinvector, a company specialized in ICT – Information and Communication Technology – which lead to the defining of a fruition system of Cultural Heritage applied to archaeological heritage.The project included 3D digital surveys of the study samples carried out using reality-based techniques, which allowed for the acquisition of metric, morphological, geometric and colorimetric data. This made it possible to elaborate three-dimensional models, based on the current configuration of the places as well as of the possible original reconfigurations.</p

Robotics and Vibration Mechanics

Robotics and vibration mechanics are among the main research areas in mechanical engineering [...

Romanesque and territory. The construction materials of Sardinian medieval churches: new approaches to the valorization, conservation and restoration

This paper is intended to illustrate a multidisciplinary research project devoted to the study of the constructive materials of the Romanesque churches in Sardinia during the “Giudicati” period (11th -13th centuries). The project focuses on the relationship between a selection of monuments and their territory, both from a historical-architectural perspective and from a more modern perspective addressing future restoration works. The methodologies of the traditional art-historical research (study of bibliographic, epigraphic and archival sources, formal reading of artifacts) are flanked by new technologies: digital surveys executed with a 3D laser-scanner, analyses of the materials (stones, mortars, bricks) with different instrumental methods: X-ray fluorescence (XRF) and inductively coupled mass spectrometry (ICP-MS) for chemical composition, X-ray diffractometer (XRD) to determine the alteration phases (e.g., soluble salts), optical microscopy and electronic (SEM) to study textures, mineral assemblages and microstructures, termogravimetric/differential scanning, calorimetric analysis (TG/DTA) for the composition of the binder mortars. This multidisciplinary approach allows the achieving of important results in an archaeometric context: 1) from a historical point of view, with the possible identification of ancient traffics, trade routes, sources of raw materials, construction phases, wall textures; 2) from a conservative point of view, by studying chemical and physical weathering processes of stone materials compatible for replacement in case of future restoration works. Sardinian Romanesque architectural heritage is particularly remarkable: about 200 churches of different types and sizes, with the almost exclusive use of cut stones. Bi- or poly-chromy, deriving from the use of different building materials, characterizes many of these monuments, becoming also a vehicle for political and cultural meanings. The paper will present some case studies aimed to illustrate the progress of the project and the results achieved

The effects of physical activity on balance and postural control in people with down syndrome

People with Down Syndrome (DS) often have impaired balance and postural control and result as less active than their peers, that can lead to reduced quality of life and movement skills. Effects of physical activity may be important in preventing falling risk and health consequences in people with DS. In this context, we conducted a literature search of original articles, published between January 2010 and January 2020, on the effects of physical activity on balance and postural control in people with DS. We found 16 articles from almost all continents, investigating the effects of different types of physical activity on static and dynamic balance and postural control. The included studies reported improvements in both static and dynamic balance with exercise programmes lasting at least 6 weeks and containing strength, aerobic and sensorimotor training. However, the most suitable type of physical activity for people with DS is not clear. In conclusion, physical activity is highly recommendable in people with DS, to improve their balance and prevent falling risk

Calculating Nonlocal Optical Properties of Structures with Arbitrary Shape

In a recent Letter [Phys. Rev. Lett. 103, 097403 (2009)], we outlined a computational method to calculate the optical properties of structures with a spatially nonlocal dielectric function. In this Article, we detail the full method, and verify it against analytical results for cylindrical nanowires. Then, as examples of our method, we calculate the optical properties of Au nanostructures in one, two, and three dimensions. We first calculate the transmission, reflection, and absorption spectra of thin films. Because of their simplicity, these systems demonstrate clearly the longitudinal (or volume) plasmons characteristic of nonlocal effects, which result in anomalous absorption and plasmon blueshifting. We then study the optical properties of spherical nanoparticles, which also exhibit such nonlocal effects. Finally, we compare the maximum and average electric field enhancements around nanowires of various shapes to local theory predictions. We demonstrate that when nonlocal effects are included, significant decreases in such properties can occur.Comment: 30 pages, 12 figures, 1 tabl