3,910 research outputs found
A Survey on Wireless Sensor Network Security
Wireless sensor networks (WSNs) have recently attracted a lot of interest in
the research community due their wide range of applications. Due to distributed
nature of these networks and their deployment in remote areas, these networks
are vulnerable to numerous security threats that can adversely affect their
proper functioning. This problem is more critical if the network is deployed
for some mission-critical applications such as in a tactical battlefield.
Random failure of nodes is also very likely in real-life deployment scenarios.
Due to resource constraints in the sensor nodes, traditional security
mechanisms with large overhead of computation and communication are infeasible
in WSNs. Security in sensor networks is, therefore, a particularly challenging
task. This paper discusses the current state of the art in security mechanisms
for WSNs. Various types of attacks are discussed and their countermeasures
presented. A brief discussion on the future direction of research in WSN
security is also included.Comment: 24 pages, 4 figures, 2 table
Face recognition technologies for evidential evaluation of video traces
Human recognition from video traces is an important task in forensic investigations and evidence evaluations. Compared with other biometric traits, face is one of the most popularly used modalities for human recognition due to the fact that its collection is non-intrusive and requires less cooperation from the subjects. Moreover, face images taken at a long distance can still provide reasonable resolution, while most biometric modalities, such as iris and fingerprint, do not have this merit. In this chapter, we discuss automatic face recognition technologies for evidential evaluations of video traces. We first introduce the general concepts in both forensic and automatic face recognition , then analyse the difficulties in face recognition from videos . We summarise and categorise the approaches for handling different uncontrollable factors in difficult recognition conditions. Finally we discuss some challenges and trends in face recognition research in both forensics and biometrics . Given its merits tested in many deployed systems and great potential in other emerging applications, considerable research and development efforts are expected to be devoted in face recognition in the near future
Image quality and high contrast improvements on VLT/NACO
NACO is the famous and versatile diffraction limited NIR imager and
spectrograph with which ESO celebrated 10 years of Adaptive Optics at the VLT.
Since two years a substantial effort has been put in to understanding and
fixing issues that directly affect the image quality and the high contrast
performances of the instrument. Experiments to compensate the non-common-path
aberrations and recover the highest possible Strehl ratios have been carried
out successfully and a plan is hereafter described to perform such measurements
regularly. The drift associated to pupil tracking since 2007 was fixed in
October 2011. NACO is therefore even better suited for high contrast imaging
and can be used with coronagraphic masks in the image plane. Some contrast
measurements are shown and discussed. The work accomplished on NACO will serve
as reference for the next generation instruments on the VLT, especially those
working at the diffraction limit and making use of angular differential imaging
(i.e. SPHERE, VISIR, possibly ERIS).Comment: 14 pages, 5 figures, SPIE 2012 Astronomical Instrumentation
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