Search results for "Positioning"
showing 10 items of 256 documents
Relativistic positioning: errors due to uncertainties in the satellite world lines
2014
Global navigation satellite systems use appropriate satellite constellations to get the coordinates of an user -close to Earth- in an almost inertial reference system. We have simulated both GPS and GALILEO constellations. Uncertainties in the satellite world lines lead to dominant positioning errors. In this paper, a detailed analysis of these errors is developed inside a great region surrounding Earth. This analysis is performed in the framework of the so-called relativistic positioning systems. Our study is based on the Jacobian, J, of the transformation giving the emission coordinates in terms of the inertial ones. Around points of vanishing J, positioning errors are too large. We show …
Construction of large-area micro-pattern gaseous detectors
2016
Particle physics experiments often comprise tracking detectors with areas of up to a few square meters. If a spatial resolution of the order of 100μm and high-rate capability are required, Micro Pattern Gaseous Detectors (MPGD) are a cost-effective solution. However, the construction of large-area MPGDs is challenging, since tight fabrication tolerances have to be met to guarantee a stable and homogeneous performance. A precision granite table and an automated 3-D positioning system with an attached laser sensor, both inside a laminar-flow cell, have therefore been set up in the PRISMA Detector Lab at Mainz. Currently, this infrastructure is used to produce drift panels for the upgrade of t…
Two-dimensional approach to relativistic positioning systems
2006
A relativistic positioning system is a physical realization of a coordinate system consisting in four clocks in arbitrary motion broadcasting their proper times. The basic elements of the relativistic positioning systems are presented in the two-dimensional case. This simplified approach allows to explain and to analyze the properties and interest of these new systems. The positioning system defined by geodesic emitters in flat metric is developed in detail. The information that the data generated by a relativistic positioning system give on the space-time metric interval is analyzed, and the interest of these results in gravimetry is pointed out.
Positioning in a flat two-dimensional space-time: the delay master equation
2010
The basic theory on relativistic positioning systems in a two-dimensional space-time has been presented in two previous papers [Phys. Rev. D {\bf 73}, 084017 (2006); {\bf 74}, 104003 (2006)], where the possibility of making relativistic gravimetry with these systems has been analyzed by considering specific examples. Here we study generic relativistic positioning systems in the Minkowski plane. We analyze the information that can be obtained from the data received by a user of the positioning system. We show that the accelerations of the emitters and of the user along their trajectories are determined by the sole knowledge of the emitter positioning data and of the acceleration of only one …
The positioning system of the ANTARES Neutrino Telescope
2012
The ANTARES neutrino telescope, located 40km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning sys…
Bluetooth Base Station Minimal Deployment for High Definition Positioning
2005
This paper discusses our approach to the problem of arranging a Bluetooth based positioning system capable of providing people coordinates in a given area with an accuracy as high as possible. Our strategy focuses on optimizing the disposition of a minimal number of available Bluetooth base stations in a subset of locations which are the only ones permitted by site characteristics and constraints. We used a genetic algorithm to this purpose and a layout chromosome whose best evolution suggested us how to deploy a minimal set of Bluetooth base stations. As a case study, we discuss our experiments and results which deal with a late middle age castle in Sicily where we carried out many trials.
Integration of WiFi ToF Positioning System in the Open, Flexible and Adaptive WiSHFUL Architecture
2017
We integrate a prototypeWiFi Time-of-Flight (ToF) ranging and positioning system in the WiSHFUL software platforms and hardware radios for experimental prototyping. Users have access to ToF measurements as well as computed positions through unified programming interfaces that make possible to investigate innovative positioning and networking solutions. TRUE pub
Helmet continuous positive airway pressure and prone positioning: A proposal for an early management of COVID-19 patients
2020
In late December 2019, clusters of patients with interstitial pneumonia of unknown cause were reported by some local health facilities in Wuhan (China). The Chinese Centre for Disease Control conducted an epidemiologic and etiologic investigation, leading to the identification of a novel coronavirus (SARS-CoV-2).1, 2 On March 11th, the World Health Organization (WHO) declared the novel coronavirus disease (COVID-19) a pandemic. In the area of Wuhan, COVID-19 mainly affected male patients (around 60%), with a median age of about 50 years; 40% of patients developed Acute Respiratory Distress Syndrome (ARDS) 5% requiring intensive care. The mortality rate was around 2%.3, 4 However, Grasselli …
Bilateral thoracoscopic thymectomy using a novel positioning system.
2013
Several techniques of bilateral video-assisted thoracoscopic extended thymectomy have been proposed, and each has its own proponents. We summarize our experience in 20 patients who underwent bilateral video-assisted thoracoscopic extended thymectomy, using a new patient positioning that amplifies the thoracoscopic view of the cardiophrenic regions which are often difficult to visualize with standard techniques. In all cases, en-bloc thymectomy with complete dissection of the mediastinal fatty tissue was achieved without sternal retractors or additional incisions.
The use of video-assisted thoracic surgery in the management of Pancoast tumours
2010
We describe our experience using video-assisted thoracic surgery (VATS) as an adjunct to the surgical management of Pancoast tumors. Between March 2004 and November 2009, 13 patients with Pancoast tumors were included in this study. Surgery was performed by positioning the patient to allow either an anterior or a posterior thoracotomy. VATS was employed to explore the pleural cavity, to optimize the surgical access and as an assistance during surgical resection. Three patients with pleural carcinosis at thoracoscopy did not undergo further surgery. Seven lobectomies and three wedge resections were performed with an en bloc chest-wall resection and mediastinal lymphadenectomy. The surgical a…