8,036 research outputs found
A target guided subband filter for acoustic event detection in noisy environments using wavelet packets
This paper deals with acoustic event detection (AED), such as screams, gunshots, and explosions, in noisy environments. The main aim is to improve the detection performance under adverse conditions with a very low signal-to-noise ratio (SNR). A novel filtering method combined with an energy detector is presented. The wavelet packet transform (WPT) is first used for time-frequency representation of the acoustic signals. The proposed filter in the wavelet packet domain then uses a priori knowledge of the target event and an estimate of noise features to selectively suppress the background noise. It is in fact a content-aware band-pass filter which can automatically pass the frequency bands that are more significant in the target than in the noise. Theoretical analysis shows that the proposed filtering method is capable of enhancing the target content while suppressing the background noise for signals with a low SNR. A condition to increase the probability of correct detection is also obtained. Experiments have been carried out on a large dataset of acoustic events that are contaminated by different types of environmental noise and white noise with varying SNRs. Results show that the proposed method is more robust and better adapted to noise than ordinary energy detectors, and it can work even with an SNR as low as -15 dB. A practical system for real time processing and multi-target detection is also proposed in this work
Analysis domain model for shared virtual environments
The field of shared virtual environments, which also
encompasses online games and social 3D environments, has a
system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model
Uncovering Vulnerable Industrial Control Systems from the Internet Core
Industrial control systems (ICS) are managed remotely with the help of
dedicated protocols that were originally designed to work in walled gardens.
Many of these protocols have been adapted to Internet transport and support
wide-area communication. ICS now exchange insecure traffic on an inter-domain
level, putting at risk not only common critical infrastructure but also the
Internet ecosystem (e.g., DRDoS~attacks).
In this paper, we uncover unprotected inter-domain ICS traffic at two central
Internet vantage points, an IXP and an ISP. This traffic analysis is correlated
with data from honeypots and Internet-wide scans to separate industrial from
non-industrial ICS traffic. We provide an in-depth view on Internet-wide ICS
communication. Our results can be used i) to create precise filters for
potentially harmful non-industrial ICS traffic, and ii) to detect ICS sending
unprotected inter-domain ICS traffic, being vulnerable to eavesdropping and
traffic manipulation attacks
Self-Learning Classifier for Internet traffic
Network visibility is a critical part of traffic engineering, network management, and security. Recently, unsupervised algorithms have been envisioned as a viable alternative to automatically identify classes of traffic. However, the accuracy achieved so far does not allow to use them for traffic classification in practical scenario. In this paper, we propose SeLeCT, a Self-Learning Classifier for Internet traffic. It uses unsupervised algorithms along with an adaptive learning approach to automatically let classes of traffic emerge, being identified and (easily) labeled. SeLeCT automatically groups flows into pure (or homogeneous) clusters using alternating simple clustering and filtering phases to remove outliers. SeLeCT uses an adaptive learning approach to boost its ability to spot new protocols and applications. Finally, SeLeCT also simplifies label assignment (which is still based on some manual intervention) so that proper class labels can be easily discovered. We evaluate the performance of SeLeCT using traffic traces collected in different years from various ISPs located in 3 different continents. Our experiments show that SeLeCT achieves overall accuracy close to 98%. Unlike state-of-art classifiers, the biggest advantage of SeLeCT is its ability to help discovering new protocols and applications in an almost automated fashio
iTeleScope: Intelligent Video Telemetry and Classification in Real-Time using Software Defined Networking
Video continues to dominate network traffic, yet operators today have poor
visibility into the number, duration, and resolutions of the video streams
traversing their domain. Current approaches are inaccurate, expensive, or
unscalable, as they rely on statistical sampling, middle-box hardware, or
packet inspection software. We present {\em iTelescope}, the first intelligent,
inexpensive, and scalable SDN-based solution for identifying and classifying
video flows in real-time. Our solution is novel in combining dynamic flow rules
with telemetry and machine learning, and is built on commodity OpenFlow
switches and open-source software. We develop a fully functional system, train
it in the lab using multiple machine learning algorithms, and validate its
performance to show over 95\% accuracy in identifying and classifying video
streams from many providers including Youtube and Netflix. Lastly, we conduct
tests to demonstrate its scalability to tens of thousands of concurrent
streams, and deploy it live on a campus network serving several hundred real
users. Our system gives unprecedented fine-grained real-time visibility of
video streaming performance to operators of enterprise and carrier networks at
very low cost.Comment: 12 pages, 16 figure
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