912 resultados para Access Control
Resumo:
We present an algorithm to process images of reflected Placido rings captured by a commercial videokeratoscope. Raw data are obtained with no Cartesian-to-polar-coordinate conversion, thus avoiding interpolation and associated numerical artifacts. The method provides a characteristic equation for the device and is able to process around 6 times more corneal data than the commercial software. Our proposal allows complete control over the whole process from the capture of corneal images until the computation of curvature radii.
Resumo:
Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework.
Resumo:
The current trend in the evolution of sensor systems seeks ways to provide more accuracy and resolution, while at the same time decreasing the size and power consumption. The use of Field Programmable Gate Arrays (FPGAs) provides specific reprogrammable hardware technology that can be properly exploited to obtain a reconfigurable sensor system. This adaptation capability enables the implementation of complex applications using the partial reconfigurability at a very low-power consumption. For highly demanding tasks FPGAs have been favored due to the high efficiency provided by their architectural flexibility (parallelism, on-chip memory, etc.), reconfigurability and superb performance in the development of algorithms. FPGAs have improved the performance of sensor systems and have triggered a clear increase in their use in new fields of application. A new generation of smarter, reconfigurable and lower power consumption sensors is being developed in Spain based on FPGAs. In this paper, a review of these developments is presented, describing as well the FPGA technologies employed by the different research groups and providing an overview of future research within this field.
Control and Guidance of Low-Cost Robots via Gesture Perception for Monitoring Activities in the Home
Resumo:
This paper describes the development of a low-cost mini-robot that is controlled by visual gestures. The prototype allows a person with disabilities to perform visual inspections indoors and in domestic spaces. Such a device could be used as the operator's eyes obviating the need for him to move about. The robot is equipped with a motorised webcam that is also controlled by visual gestures. This camera is used to monitor tasks in the home using the mini-robot while the operator remains quiet and motionless. The prototype was evaluated through several experiments testing the ability to use the mini-robot’s kinematics and communication systems to make it follow certain paths. The mini-robot can be programmed with specific orders and can be tele-operated by means of 3D hand gestures to enable the operator to perform movements and monitor tasks from a distance.
Resumo:
[From the Introduction]. Information gives knowledge and knowledge gives power. Though in all EC Member States, the task to protect the environment is given to the administration, it is obvious that the administration is not the owner of the environment. The environment is everybody's. It is for this reason that administrative decisions which affect the environment must be transparent, open and must strike a balance between the general interest to preserve, protect and improve the quality of the environment on the one hand, the satisfying of specific private or public interests on the other hand. In order to allow at least a certain control of whether the administration strikes the right balance between the need to protect the environment and other legitimate or less legitimate needs, it appears normal and self-evident that information on the environment which is in the hands of public authorities, be also made available to the public and to citizens.
Resumo:
Standards reduce production costs and increase products’ value to consumers. Standards however entail risks of anti-competitive abuse. After the adoption of a standard, the chosen technology normally lacks credible substitutes. The owner of the patented technology might thus have additional market power relative to locked-in licensees, and might exploit this power to charge higher access rates. In the economic literature this phenomenon is referred to as ‘hold-up’. To reduce the risk of hold-up, standard-setting organisations often require patent holders to disclose their standard-essential patents before the adoption of the standard and to commit to license on fair, reasonable and non-discriminatory (FRAND) terms. The European Commission normally investigates unfair pricing abuse in a standard-setting context if a patent holder who committed to FRAND ex-ante is suspected not to abide to it ex-post. However, this approach risks ignoring a number of potential abuses which are likely harmful for welfare. That can happen if, for example, ex-post a licensee is able to impose excessively low access rates (‘reverse hold-up’) or if a patent holder acquires additional market power thanks to the standard but its essential patents are not encumbered by FRAND commitments, for instance because the patent holder did not directly participate to the standard setting process and was therefore not required by the standard-setting organisations to commit to FRAND ex-ante. A consistent policy by the Commission capable of tackling all sources of harm should be enforced regardless of whether FRAND commitments are given. Antitrust enforcement should hinge on the identification of a distortion in the bargaining process around technology access prices, which is determined by the adoption of the standard and is not attributable to pro-competitive merits of any of the involved players.
Resumo:
The upper 200 m of the sediments recovered during IODP Leg 302, the Arctic Coring Expedition (ACEX), to the Lomonosov Ridge in the central Arctic Ocean consist almost exclusively of detrital material. The scarcity of biostratigraphic markers severely complicates the establishment of a reliable chronostratigraphic framework for these sediments, which contain the first continuous record of the Neogene environmental and climatic evolution of the Arctic region. Here we present profiles of cosmogenic 10Be together with the seawater-derived fraction of stable 9Be obtained from the ACEX cores. The down-core decrease of 10Be/9Be provides an average sedimentation rate of 14.5 ± 1 m/Ma for the uppermost 151 m of the ACEX record and allows the establishment of a chronostratigraphy for the past 12.3 Ma. The age-corrected 10Be concentrations and 10Be/9Be ratios suggest the existence of an essentially continuous sea ice cover over the past 12.3 Ma.
Resumo:
Planktic d18O and d13C records and point count records of biogenic, volcanic, and nonvolcanic terrigenous [ice-rafted debris (IRD)] sediment components from Hole 919A in the Irminger basin, northern North Atlantic provide a comprehensive dataset from which a paleoceanographic reconstruction for the last 630 kyr has been developed. The paleoceanographic evolution of the Irminger basin during this time contains both long-term patterns and significant developmental steps. One long-term pattern observed is the persistent deposition of hematite-stained ice-rafted debris. This record suggests that the modern and late Pleistocene discharges of icebergs from northern redbed regions to the Irminger Sea lie in the low end of the range observed over the last 630 kyr. In addition, Arctic front fluctuations appear to have been the main controlling factor on the long-term accumulation patterns of IRD and planktic biogenic groups. The Hole 919A sediment record also contains a long-term association between felsic volcanic ash abundances and light d18O excursions in both interglacial and glacial stages, which suggests a causal link between deglaciations and explosive Icelandic eruptions. A significant developmental step in the paleoceanographic reconstruction based on benthic evidence was for diminished supply of Denmark Strait Overflow Water (DSOW) beginning at ~380 ka, possibly initiated by the influx of meltwater from broad-scale iceberg discharges along the east Greenland coast. There is also planktic evidence of a two-step cooling of sea surface conditions in the Irminger basin, first at ~338-309 ka and later at ~211-190 ka, after which both glacials and interglacials were colder as the Arctic front migrated southeast of Site 919. In addition to offering these findings, this reconstruction provides a longer-term geologic context for the interpretation of more recent paleoceanographic events and patterns of deposition from this region.