102,002 research outputs found
Design Solutions For Modular Satellite Architectures
No full textThe cost-effective access to space envisaged by ESA would open a wide range of new opportunities and markets, but is still many years ahead. There is still a lack of devices, circuits, systems which make possible to develop satellites, ground stations and related services at costs compatible with the budget of academic institutions and small and medium enterprises (SMEs). As soon as the development time and cost of small satellites will fall below a certain threshold (e.g. 100,000 to 500,000 €), appropriate business models will likely develop to ensure a cost-effective and pervasive access to space, and related infrastructures and services. These considerations spurred the activity described in this paper, which is aimed at: - proving the feasibility of low-cost satellites using COTS (Commercial Off The Shelf) devices. This is a new trend in the space industry, which is not yet fully exploited due to the belief that COTS devices are not reliable enough for this kind of applications; - developing a flight model of a flexible and reliable nano-satellite with less than 25,000€; - training students in the field of avionics space systems: the design here described is developed by a team including undergraduate students working towards their graduation work. The educational aspects include the development of specific new university courses; - developing expertise in the field of low-cost avionic systems, both internally (university staff) and externally (graduated students will bring their expertise in their future work activity); - gather and cluster expertise and resources available inside the university around a common high-tech project; - creating a working group composed of both University and SMEs devoted to the application of commercially available technology to space environment. The first step in this direction was the development of a small low cost nano-satellite, started in the year 2004: the name of this project was PiCPoT (Piccolo Cubo del Politecnico di Torino, Small Cube of Politecnico di Torino). The project was carried out by some departments of the Politecnico, in particular Electronics and Aerospace. The main goal of the project was to evaluate the feasibility of using COTS components in a space project in order to greatly reduce costs; the design exploited internal subsystems modularity to allow reuse and further cost reduction for future missions. Starting from the PiCPoT experience, in 2006 we began a new project called ARaMiS (Speretta et al., 2007) which is the Italian acronym for Modular Architecture for Satellites. This work describes how the architecture of the ARaMiS satellite has been obtained from the lesson learned from our former experience. Moreover we describe satellite operations, giving some details of the major subsystems. This work is composed of two parts. The first one describes the design methodology, solutions and techniques that we used to develop the PiCPoT satellite; it gives an overview of its operations, with some details of the major subsystems. Details on the specifications can also be found in (Del Corso et al., 2007; Passerone et al, 2008). The second part, indeed exploits the experience achieved during the PiCPoT development and describes a proposal for a low-cost modular architecture for satellite
Cardiac Perforation by Atrial Septal Defect Closure Devices A Potentially Catastrophic and Still Unclear Event
No full textCardiac perforation by atrial septal defect closure devices: a potentially catastrophic and still unclear event
3DV — An embedded, dense stereovision-based depth mapping system
No full textThis paper describes the architecture and hardware implementation of an embedded, low-cost and low-power dense stereo reconstruction system, running at 30 fps at VGA resolution. The processing pipeline includes an initial image rectification stage, a cost generation unit based on the non-parametric census transform, a state-of-the-art Semi-Global cost optimization stage, and a final minimization and noise suppression step. The hardware implementation is based on a Xilinx ZynqTM System-on-Chip, which besides the FPGA provides a physical dual-core ARM CPU, which is exploited for control and to deliver output over the integrated Gigabit Ethernet connection
[Indications for permanent cardiac pacemaking].
No full textTechnical improvements have considerably extended the indications for the implantation of pacemakers. Nearly all forms of bradyarrhythmia and some forms of tachycardia, including sinus node disease, have gradually been added alongside stable A-V blocks, while preventive implantation is now commonly indicated in asymptomatic forms and bradycardia due to drugs. The recent appearance of rapid-pulse and scanning pacemakers has further extended their indication to cover other forms of ectopic and reciprocating tachycardia
Trans-apical aortic valve implantation complicated by left main occlusion
No full textTranscatheter aortic valve implantation (TAVI) is a highly effective procedure for selected patients who are at high risk for aortic valve replacement; however, the incidence of severe complications is still relevant. Coronary occlusion during TAVI is a life-threatening complication that requires immediate diagnosis and treatment. We report the case of an 87-years-old woman affected by severe aortic stenosis, symptomatic for refractory heart failure, who underwent urgent balloon aortic valvuloplasty and subsequent elective transapical aortic valve implantation. Valve deployment was complicated by cardiac arrest and hemodynamic collapse, and left main coronary artery occlusion was recognized and successfully recovered by balloon angioplasty and stent implantation. Patient is alive and well 6 months after procedure
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