931 resultados para High speed trains


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Subpixel techniques are commonly used to increase the spatial resolution in tracking tasks. Object tracking with targets of known shape permits obtaining information about object position and orientation in the three-dimensional space. A proper selection of the target shape allows us to determine its position inside a plane and its angular and azimuthal orientation under certain limits. Our proposal is demonstrated both numerical and experimentally and provides an increase the accuracy of more than one order of magnitude compared to the nominal resolution of the sensor. The experiment has been performed with a high-speed camera, which simultaneously provides high spatial and temporal resolution, so it may be interesting for some applications where this kind of targets can be attached, such as vibration monitoring and structural analysis.

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We present a targetless motion tracking method for detecting planar movements with subpixel accuracy. This method is based on the computation and tracking of the intersection of two nonparallel straight-line segments in the image of a moving object in a scene. The method is simple and easy to implement because no complex structures have to be detected. It has been tested and validated using a lab experiment consisting of a vibrating object that was recorded with a high-speed camera working at 1000 fps. We managed to track displacements with an accuracy of hundredths of pixel or even of thousandths of pixel in the case of tracking harmonic vibrations. The method is widely applicable because it can be used for distance measuring amplitude and frequency of vibrations with a vision system.

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In today's internet world, web browsers are an integral part of our day-to-day activities. Therefore, web browser security is a serious concern for all of us. Browsers can be breached in different ways. Because of the over privileged access, extensions are responsible for many security issues. Browser vendors try to keep safe extensions in their official extension galleries. However, their security control measures are not always effective and adequate. The distribution of unsafe extensions through different social engineering techniques is also a very common practice. Therefore, before installation, users should thoroughly analyze the security of browser extensions. Extensions are not only available for desktop browsers, but many mobile browsers, for example, Firefox for Android and UC browser for Android, are also furnished with extension features. Mobile devices have various resource constraints in terms of computational capabilities, power, network bandwidth, etc. Hence, conventional extension security analysis techniques cannot be efficiently used by end users to examine mobile browser extension security issues. To overcome the inadequacies of the existing approaches, we propose CLOUBEX, a CLOUd-based security analysis framework for both desktop and mobile Browser EXtensions. This framework uses a client-server architecture model. In this framework, compute-intensive security analysis tasks are generally executed in a high-speed computing server hosted in a cloud environment. CLOUBEX is also enriched with a number of essential features, such as client-side analysis, requirements-driven analysis, high performance, and dynamic decision making. At present, the Firefox extension ecosystem is most susceptible to different security attacks. Hence, the framework is implemented for the security analysis of the Firefox desktop and Firefox for Android mobile browser extensions. A static taint analysis is used to identify malicious information flows in the Firefox extensions. In CLOUBEX, there are three analysis modes. A dynamic decision making algorithm assists us to select the best option based on some important parameters, such as the processing speed of a client device and network connection speed. Using the best analysis mode, performance and power consumption are improved significantly. In the future, this framework can be leveraged for the security analysis of other desktop and mobile browser extensions, too.

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- Mobile telecommunications markets are an important part of the European Commission’s strategy for the completion of the European Union Digital Single. The use of mobile telecommunications – particularly mobile data access – is growing and becoming an increasingly important input for the economy. - The EU currently does not have a unified mobile telecommunications market. The EU compares favourably to the United States in terms of prices and connection speed, but lags behind in terms of coverage of high-speed 4G wireless connections. -Europe’s long-term goal should be to make data access easier by increasing highspeed wireless coverage while keeping prices down for users. An increase in cross-border competition could help to achieve that goal. - The Commission has two important levers to help stimulate cross-border supply:(a) ensuring competition in intra-country mobile markets in order to provide an incentive for operators to expand into other jurisdictions, and (b) reducing mobile operators’ costs of expansion into multiple EU countries. The further development of policies on international roaming and radio spectrum management will be central to this effort.

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Plasmodium parasites, the causative agents of malaria, first invade and develop within hepatocytes before infecting red blood cells and causing symptomatic disease. Because of the low infection rates in vitro and in vivo, the liver stage of Plasmodium infection is not very amenable to biochemical assays, but the large size of the parasite at this stage in comparison with Plasmodium blood stages makes it accessible to microscopic analysis. A variety of imaging techniques has been used to this aim, ranging from electron microscopy to widefield epifluorescence and laser scanning confocal microscopy. High-speed live video microscopy of fluorescent parasites in particular has radically changed our view on key events in Plasmodium liver-stage development. This includes the fate of motile sporozoites inoculated by Anopheles mosquitoes as well as the transport of merozoites within merosomes from the liver tissue into the blood vessel. It is safe to predict that in the near future the application of the latest microscopy techniques in Plasmodium research will bring important insights and allow us spectacular views of parasites during their development in the liver.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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Decreasing vehicle understeer was strongly associated with the likelihood of control loss following both the unexpected and expected tire failures. Knowledge of the imminent tread separation reduced the overall probability of control loss from 55% to 20% and had a significant effect on how quickly drivers responded as well as on the nature of their initial responses (i.e., steering orbraking). Driver age was marginally associated with increased likelihood of vehicle control loss, but only on unexpected trials. Vehicle speed at the time of first steering input also contributed to the probability of control loss. Neither the location of the tire that failed (left rear vs. right rear) nor the specific instructions about how best to respond to the tread separation influenced the probability of control loss. Differences associated with vehicle understeer conditions observed in the present study were large and consistent, independent of driver expectations and across driver age groups. It is thus fair to conclude that in the event of a complete rear-tire detread, the increased difficulty in vehicle handling and the associated increased likelihood of loss of vehicle control with decreasing vehicle understeer generalize to real-world driving.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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Includes index.