101,871 research outputs found
CubeSat constellations for disaster management in remote areas
No full textIn recent years, CubeSats have considerably extended their range of possible applications, from a low cost means to train students and young researchers in space related activities up to possible complementary solutions to larger missions. Increasingly popular, whereas CubeSats are still not a solution for all types of missions, they offer the possibility of performing ambitious scientific experiments. Especially worth considering is the possibility of performing Distributed Space Missions, in which CubeSat systems can be used to increase observation sampling rates and resolutions, as well as to perform tasks that a single satellite is unable to handle. The cost of access to space for traditional Earth Observation CEO) missions is still quite high. Efficient architecture design would allow reducing mission costs by employing CubeSat systems, while maintaining a level of performance that, for some applications, could be close to that provided by larger platforms, and decreasing the time needed to design and deploy a fully functional constellation. For these reasons many countries, including developing nations, agencies and organizations are looking to CubeSat platforms to access space cheaply with, potentially, tens of remote sensing satellites. During disaster management, real-time, fast and continuous information broadcast is a fundamental requirement. In this sense, a constellation of small satellites can considerably decrease the revisit time (defined as the time elapsed between two consecutive observations of the same point on Earth by a satellite) over remote areas, by increasing the number of spacecraft properly distributed in orbit. This allows collecting as much data as possible for the use by Disaster Management Centers. This paper describes the characteristics of a constellation of CubeSats built to enable access over the most remote regions of Brazil, supporting an integrated system for mitigating environmental disasters in an attempt to prevent the catastrophic effects of natural events such as heavy rains that cause flooding. In particular, the paper defines the number of CubeSats and the orbital planes required to minimize the revisit time, depending on the application that is the mission objective. Each CubeSat is equipped with the suitable payloads and possesses the autonomy and pointing capabilities needed to meet the mission requirements. Thanks to the orbital features of the constellation, this service could be exploited by other tropical countries. Coverage of other areas of the Earth might be provided by adjusting the number and in-orbit distribution of the spacecraft
Disaster management of remote areas by constellation of CubeSats
No full textCubeSats have become very popular in the last decade, mostly as a low cost means to train students and young researchers in the space engineering and science. Since the cost of accessing the space is still quite relevant for planning and execute traditional Earth Observation (EO) missions, the CubeSat could be an interesting solution to reduce mission costs maintaining the performances and reducing the time of the design phase to have a full functional constellation. For these reasons several countries, agencies and organizations are looking to CubeSat platforms to access space taking advantage of the potential availability of tens of remote sensing satellites. During disaster management, real-time, fast and continuous information broadcast is a fundamental requirement. In this sense, a constellation of small satellites can considerably increase the revisit time (defined as the time elapsed between two consecutive observations of the same point on earth by a satellite) over remote areas, by increasing the number of spacecrafts properly distributed in orbit. This allows to collect and send as much data as possible to Disasters Management Centers. This paper describes the characteristics of a constellation of CubeSats built to enable access over the most remote regions of Brazil. In particular, the paper defines the number of cubesat and the orbital planes required to minimize the revisit time, depending on the application that is the mission objective. Each CubeSat is equipped with the suitable optical payloads and possesses the autonomy and pointing capabilities in order to meet the requirements of the mission. Thanks to the orbital features of the constellation, this service could be exploited by the other countries in the tropical region of the Earth. Coverage of other areas of the Earth might be provided adjusting the number and in orbit distribution of the spacecrafts
Application of an FBG sensors system for structural health monitoring and high performance trimming on racing yacht
No full textReal time Structural Health Monitoring (SHM) is a requirement in all fields of engineering and is aimed at assuring the safety of the structures themselves and of the people who use them or move around them. This leads to the need for a monitoring system, stable and effective, which allows long term measurement campaigns, even throughout the whole lifetime of a structure; such a system, integrated with the structure to be monitored in real time, shall be invisible, durable (more of the structure itself), but should not interfere with the physical characteristic being measured (strain, acceleration, temperature, etc). The same requirements are also present in many sports: motor racing (cars and motorbikes), aerobatics and also yacht racing (regattas), where a monitoring system helps checking the status of the structure (car, bike, airplane, boat), for the safety of people on board, and for improving performance by making real time variation on aerodynamic and mechanical components (such as spoilers, wings, winglets, brakes, suspension), as it is now being done for over thirty years with the telemetry. Telemetry has been a key factor in modern motor racing: engineers analyze the vast amount of data collected during a test or a race (accelerations, temperature, speed of the wheels and displacement of suspensions) and use them to tune the car for optimizing performance. In this paper a monitoring and trimming system for racing yachts based on fiber optic FBG sensors integrated inside the structure itself is presented. Several applications are described where sensing system has been installed on the boat mast, either glued externally or embedded inside the material (carbon fiber reinforced composite, CFRC) during manufacturing, and on the sails. The same system can be used to monitor hull, keel, rudder, etc. Prevention of serious damage on a racing yacht might be achieved by monitoring the loading conditions and by inspecting the structural integrity, but if it is not easy to estimate loads (generally due to waves and winds) it could be easier to check the structural integrity in real time. © 2011 IEEE
SURFACE DAMAGE OF STAINLESS STEEL EN3358 SUBJECT TO FRICTION, IMPULSIVE ACCELERATION AND CORROSIVE ENVIRONMENT
No full textThe present paper describe the failure analysis of an aircraft component subjected to several episodes of in service failure, resulted in loss of the aircraft safety. Modern aircrafts are provided with mechanical systems which have the task to open not pressurized hatches during landing. The components of such systems are subject to considerable mechanical stresses in harsh environment (presence of moisture and pollutants, significant and sudden temperature variations). The system is constituted by a sliding piston, and related nipple, assisted in the movement by 4 steel balls which act as a ball bearing, the whole system is activated by a preloaded spring. The machined parts, nipple and piston, are made of N3358 steel (X3CrNiMo13-8-2), an austenitic stainless steel with very low content of carbon often used in the aerospace. The samples provided by the manufacturer present different types of damage all referable to phenomena relative to the sliding of the piston inside the nipple. Particularly, on the cylindrical sample (piston) were detected circular impressions -probably due to the ball-bearing- and various kinds of longitudinal and helicoidal grooves, due both to the original machining and to the spring. The nipple presented longitudinal grooves and residual of lubricant containing metal residues resulting from the relative sliding. The present paper describes the different damage observed and the microstructure of the material, then are reported the results obtained from the characterization of the material of the samples by means of optical and electronic microscopy, carried out to define the mechanisms involved in the system seizure. In order to define the primary cause of failure and to propose solutions to be adopted, the results of different tests were compared with system design and working data
TECHNOLOGICAL CHALLENGES FOR MANUFACTURING LARES SATELLITE
No full textLARES is a passive satellite designed to measure the gravitomagnetic field of Earth predicted by Einstein general relativity. The technique used to accurately measure the satellite position is the laser ranging technique. The satellite is uniformly covered with 92 cube corner reflectors that sends back to the ground station the laser pulses. Launch is foreseen in 2010 with the new VEGA launch vehicle. The material selected for building the satellite is a tungsten alloy. Due to this peculiar alloy used for LARES satellite, some concerns arise about the machinability of the material. Although several producers can provide several types of tungsten alloys, and there are applications that use bulk tungsten material, to our knowledge this material, very seldom used in space, was never machined with tight manufacturing tolerances and severe surface finish. Consequently some tests for machinability have been performed. Particular care has been adopted for manufacturing spherical cavities that are used to interface the separation system. Also the screws and the retainer rings for the cube corner reflector mounting system are difficult items to be manufactured in tungsten alloy, being the screw body and the ring thickness very small. All those technological challenges have been faced on several breadboards (full scale prototypes of critical small parts of the satellite)
[Long-term survival metastatic ovarian cancer elderly patient]
No full textOvarian cancer is the sixth diagnosed cancer among women worldwide, it has a high mortality and in most cases it's diagnosed in advanced stage (stage III-IV). Combination platinum-paclitaxel chemotherapy administered every 3 weeks is considered the gold standard for first-line treatment of patients with advanced ovarian cancer. Elderly patients with ovarian cancer represents a subgroup with poor prognosis because they are often treated less radically for comorbidities and age. In the present article, we report a case of a 85 year old woman who was diagnosed with stage IV ovarian carcinoma for the presence of peritoneal carcinomatosis ab initio, not radically debulked and then treated with weekly schedule platinum-based and paclitaxel. Despite not being able to complete the chemotherapy, the patient achieved excellent results and represents a case of long survival
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Purple spot damage dynamics investigated by an integrated approach on a 1244 A.D. parchment roll from the Secret Vatican Archive
No full textAncient parchments are commonly attacked by microbes, producing purple spots and detachment of the superficial layer. Neither standard cultivation nor molecular methods (DGGE) solved the issue: causative agents and colonization model are still unknown. To identify the putative causal agents, we describe the 16 S rRNA gene analysis (454-pyrosequencing) of the microbial communities colonizing a damaged parchment roll dated 1244 A.D. (A.A. Arm. I-XVIII 3328, Vatican Secret Archives). The taxa in damaged or undamaged areas of the same document were different. In the purple spots, marine halotolerant Gammaproteobacteria, mainly Vibrio, were found; these microorganisms are rare or absent in the undamaged areas. Ubiquitous and environmental microorganisms were observed in samples from both damaged and undamaged areas. Pseudonocardiales were the most common, representing the main colonizers of undamaged areas. We hypothesize a successional model of biodeterioration, based on metagenomic data and spectroscopic analysis of pigments, which help to relate the damage to a microbial agent. Furthermore, a new method (Light Transmitted Analysis) was utilized to evaluate the kind and entity of the damage to native collagen. These data give a significant advance to the knowledge in the field and open new perspectives to remediation activity on a huge amount of ancient document
- …
