Pose and Shape Reconstruction of a Noncooperative Spacecraft Using Camera and Range Measurements

Recent interest in on-orbit proximity operations has pushed towards the development of autonomous GNC strategies. In this sense, optical navigation enables a wide variety of possibilities as it can provide information not only about the kinematic state but also about the shape of the observed object. Various mission architectures have been either tested in space or studied on Earth. The present study deals with on-orbit relative pose and shape estimation with the use of a monocular camera and a distance sensor. The goal is to develop a filter which estimates an observed satellite's relative position, velocity, attitude, and angular velocity, along with its shape, with the measurements obtained by a camera and a distance sensor mounted on board a chaser which is on a relative trajectory around the target. The filter's efficiency is proved with a simulation on a virtual target object. The results of the simulation, even though relevant to a simplified scenario, show that the estimation process is successful and can be considered a promising strategy for a correct and safe docking maneuver

Wave propagation in discontinuous media

Wave propagation in discontinuous media, which is of interest for design analysis of underground structures and geotechnical works in general, is studied in this paper with the scattering matrix method. This method determines the response of a system, i.e. the discontinuous medium, excited by an elastic wave. Both P, SV or SH waves can be applied to the model with any oblique angle of incidence. The scattering matrix is composed of reflection and transmission coefficients of a single joint or a set of parallel joints. The analytical solution is obtained in the frequency domain and allows one to consider multiple wave reflections between joints. Reflected and transmitted waves are calculated for one and more joints in dry or fluid filled conditions. The solutions obtained are compared with analytical and numerical solutions available in the literature or obtained independently by using the Distinct Element Metho

Real-Axis Solution of Eliashberg Equations in Various Order-Parameter Symmetries and Tunneling Conductance of Optimally-Doped HTSC

In the present work we calculate the theoretical tunneling conductance curves of SIN junctions involving high-Tc superconductors, for different possible symmetries of the order parameter (s, d, s+id, s+d, anisotropic s and extended s). To do so, we solve the real-axis Eliashberg equations in the case of an half-filled infinite band. We show that some of the peculiar characteristics of HTSC tunneling curves (dip and hump at eV > Delta, broadening of the gap peak, zero bias and so on) can be explained in the framework of the Migdal-Eliashberg theory. The theoretical dI/dV curves calculated for the different symmetries at T=4 K are then compared to various experimental tunneling data obtained in optimally-doped BSCCO, TBCO, HBCO, LSCO and YBCO single crystals. To best fit the experimental data, the scattering by non-magnetic impurities has to be taken into account, thus limiting the sensitivity of this procedure in determining the exact gap symmetry of these materials. Finally, the effect of the temperature on the theoretical tunneling conductance is also discussed and the curves obtained at T=2 K are compared to those given by the analytical continuation of the imaginary-axis solution.Comment: 6 pages, 3 figures, Proceedings of SATT10 Conference, to be published in Int. J. Mod. Phys.

Sante De Sanctis (1862-1935), a forerunner of the 20th century research on sleep and dreaming

This article aims to reconstruct the elements of continuity and/or discontinuity in Sante De Sanctis' (1862–1935) contributions in the scientific understanding of sleep and dreaming as compared to the scientific research of his time. An Italian psychologist and psychiatrist, De Sanctis, in his work conducted between the 19th and 20th centuries, has framed the study of dreams using multi-methodology. In addition, De Sanctis experimentally established the correspondence between the deep and desynchronization phases of sleep with respect to dreaming. In this context, De Sanctis' subjects described the periodicity of sleep and consciousness, influencing the explanations of the themes that modern sleep research has, after decades, systematically studied. We demonstrate that De Sanctis' work has been underestimated, and in our opinion, deserves to be reconsidered as a source of the psychophysiological explanation of dreams and sleep. Finally, we present a graphical representation of De Sanctis' psycho- and neurophysiological model of dreamin

An Artificial Neural Network technique for on-line hotel booking

In this paper the use of Artificial Neural Networks (ANNs) in on-line booking for hotel industry is investigated. The paper details the description, the modeling and the resolution technique of on-line booking. The latter problem is modeled using the paradigms of machine learning, in place of standard `If-Then-Else' chains of conditional rules. In particular, a supervised three layers MLP neural network is adopted, which is trained using information from previous customers' reservations. Performance of our ANN is analyzed: it behaves in a quite satisfactory way in managing the (simulated) booking service in a hotel. The customer requires single or double rooms, while the system gives as a reply the confirmation of the required services, if available. Moreover, we highlight that using our approach the system proposes alternative accommodations (from two days in advance to two days later with respect to the requested day), in case rooms or services are not available. Numerical results are given, where the effectiveness of the proposed approach is critically analyzed. Finally, we outline guidelines for future research.On-line booking; hotel reservation; machine learning; supervised multilayer perceptron networks

Energy-saving optimization method for point-to-point trajectories planned via standard primitives in 1-DoF mechatronic systems

AbstractIn this work, an analytical methodology to minimize the energy expenditure of mechatronic systems performing point-to-point (PTP) trajectories based on well-known motion primitives is developed and validated. Both PTP trajectory profiles commonly used in industrial motor drives and more complex ones are investigated. Focusing on generic 1-DoF mechatronic systems moving a constant inertia load (e.g., elevators, cranes, CNC machines, Cartesian axis) and possibly equipped or retrofitted with regenerative devices, the consumed energy formulation is firstly derived. Then, the analytical optimization considering all the selected PTP trajectory profiles is computed and a generic closed-form solution is determined. Finally, numerical and experimental evaluations are done showing the effectiveness of the theoretical results and proposed methodology. In addition, all the different trajectories are compared with respect to energy consumption

Genome-Wide Multiple Sclerosis Association Data and Coagulation

The emerging concept of a crosstalk between hemostasis, inflammation, and immune system prompt recent works on coagulation cascade in multiple sclerosis (MS). Studies on MS pathology identified several coagulation factors since the beginning of the disease pathophysiology: fibrin deposition with breakdown of blood brain barrier, and coagulation factors within active plaques may exert pathogenic role, especially through the innate immune system. Studies on circulating coagulation factors showed complex imbalance involving several components of hemostasis cascade (thrombin, factor X, factor XII). To analyze the role of the coagulation process in connection with other pathogenic pathways, we implemented a systematic matching of genome-wide association studies (GWAS) data with an informative and unbiased network of coagulation pathways. Using MetaCore (version 6.35 build 69300, 2018) we analyzed the connectivity (i.e., direct and indirect interactions among two networks) between the network of the coagulation process and the network resulting from feeding into MetaCore the MS GWAS data. The two networks presented a remarkable over-connectivity: 958 connections vs. 561 expected by chance; z-score = 17.39; p-value < 0.00001. Moreover, genes coding for cluster of differentiation 40 (CD40) and plasminogen activator, urokinase (PLAU) shared both networks, pointed to an integral interplay between coagulation cascade and main pathogenic immune effectors. In fact, CD40 pathways is especially operative in B cells, that are currently a major therapeutic target in MS field. The potential interaction of PLAU with a signal of paramount importance for B cell pathogenicity, such as CD40, suggest new lines of research and pave the way to implement new therapeutic targets

Single injection dual phase CBCT technique ameliorates results of trans-arterial chemoembolization for hepatocellular cancer

Cone-beam CT (CBCT) application to the field of trans-arterial chemoembolization has been recently the focus of several researches. This imaging modality is performed with a rotation of the C-arm around the patient, without needs of patient repositioning. Datasets are immediately processed, obtaining volumetric CT-like images with the possibility of post-processing and reconstruction of images. Dual phase CBCT recently introduced in clinical practice consists in a first arterial acquisition followed by a delayed acquisition corresponding to a venous phase. The introduction of this feature has overcome the limit of single-phase acquisitions, allowing lesions characterization. Moreover these recent advantages have several intra-procedural implications. Detailed technical and acquisition parameters will be widely exposed in this review with particular attention to: catheter positioning, acquisition delay, injection parameters, patient positioning and contrast dilution. Comparison with standard of practice second line imaging [multidetector computer tomography (MDCT) and MDCT/arteriography] demonstrate the capability of detecting occult nodules providing some clinical implications thus potentially identifying a sub set of patients with aggressive disease behaviour. Other intra-procedural advantages of dual phase CBCT usage consist in a better tumor feeder visualization, reduction of proper DSA and fluoroscopic time, suggestion the presence of an extrahepatic parasitic feeder thus resulting in a more accurate treatment. Finally, the volumetrical intraprocedural evaluation of accumulation of embolic agent has proved to be correlate with treatment response if compared with MRI

Noise in multiple sclerosis: unwanted and necessary

As our knowledge about the etiology of multiple sclerosis (MS) increases, deterministic paradigms appear insufficient to describe the pathogenesis of the disease, and the impression is that stochastic phenomena (i.e. random events not necessarily resulting in disease in all individuals) may contribute to the development of MS. However, sources and mechanisms of stochastic behavior have not been investigated and there is no proposed framework to incorporate nondeterministic processes into disease biology. In this report, we will first describe analogies between physics of nonlinear systems and cell biology, showing how small-scale random perturbations can impact on large-scale phenomena, including cell function. We will then review growing and solid evidence showing that stochastic gene expression (or gene expression “noise”) can be a driver of phenotypic variation. Moreover, we will describe new methods that open unprecedented opportunities for the study of such phenomena in patients and the impact of this information on our understanding of MS course and therapy