摘要:
Systems and methods are disclosed herein for identifying an anomaly in a signal, where samples in the signal correspond to an amount of data flow in a network within a time interval, and an anomaly corresponds to at least one sample in the discrete signal having a likelihood value below a likelihood threshold. A historical probability distribution of the discrete signal is generated based on previously received samples. For each sample in a plurality of samples in the discrete signal, a likelihood is computed based at least in part on the historical probability distribution. A likelihood threshold is selected, and a set of consecutive samples is identified as an anomaly when each sample in the set has a computed likelihood below the likelihood threshold.
摘要:
Systems and methods are disclosed herein for detecting an anomaly in a discrete signal, where a long-term trend of the discrete signal is identified. Samples in the signal correspond to a number of data packets arriving at a location in a network within a time interval. The long-term trend is subtracted from the discrete signal to obtain a detrended signal. A cyclic pattern is identified in the detrended signal and is subtracted from the detrended signal to obtain a residual signal. Anomaly detection is performed on the residual signal.
摘要:
Systems and methods are described herein for detecting an anomaly in a discrete signal, where samples in the signal correspond to amounts of data flow in a network within a time interval. The discrete signal is received, and a sequence of likelihoods corresponding to the sample values in the signal is generated. The likelihoods are based at least in part on a historical probability distribution of previously received sample values, and a likelihood is a probability of occurrence of a corresponding sample value in the signal. Likelihood change points are identified in the likelihood sequence, and the discrete signal is segmented into a plurality of segments at samples corresponding to the identified change points. A segment is identified as an anomaly based on a comparison between a statistic of the segment and a statistic of the historical probability distribution.
摘要:
Systems and methods are provided for estimating missing samples in a signal. A plurality of samples in the signal is received, and a respective sample corresponds to a respective sample location in a plurality of sample locations. A subset of sample locations representing missing samples in the signal is identified, and a first and a second threshold are determined. Each threshold is an integer number of samples, and the second threshold is greater than the first threshold. A first set of consecutive sample locations from the identified subset of sample locations is formed, and the missing samples in the first set of consecutive sample locations are replaced based on a comparison between a number of locations in the first set of consecutive locations, the first threshold, and the second thresholds.
摘要:
A technique has been developed to fabricate micro- or nanopumps based on porous alumina thin films. The main body of the nanopump consists of a porous alumina thin film (containing nano-sized channels of about 40-300 nm in diameter) with conductive surfaces (e.g. Au coating layers) on both sides of the film. Through the fabrication of nanochannels in (the alumina films) and the subsequent annealing and surface activation processes, high-efficiency micro- or nanopumps can be made. The nanofluidic flow through the nanochannels of the alumina thin films is driven by an electric field with no moving parts. The flow rate (up to 50 millilitres/(min·cm2)) of water through the alumina thin film can be continuously tuned through the intensity of the electric field, i.e., the DC electric potential applied across the nanochannels.
摘要:
A technique has been developed to fabricate micro- or nanopumps based on porous alumina thin films. The main body of the nanopump consists of a porous alumina thin film (containing nano-sized channels of about 40-300 nm in diameter) with conductive surfaces (e.g. Au coating layers) on both sides of the film. Through the fabrication of nanochannels in (the alumina films) and the subsequent annealing and surface activation processes, high-efficiency micro- or nanopumps can be made. The nanofluidic flow through the nanochannels of the alumina thin films is driven by an electric field with no moving parts. The flow rate (up to 50 millilitres/(min·cm2)) of water through the alumina thin film can be continuously tuned through the intensity of the electric field, i.e., the DC electric potential applied across the nanochannels.