scholarly journals Random Response to Periodic Excitation With Correlated Disturbances

1995 ◽  
Author(s):  
Zhikun Hou ◽  
Yunshen Zhou ◽  
Mikhail F. Dimentberg ◽  
Mohammad N. Noori
Keyword(s):  
Phase Modulation ◽  
Cross Correlation ◽  
Gaussian White Noise ◽  
Random Phase ◽  
Fourth Moment ◽  
Periodic Excitation ◽  
The Cross ◽  
The Moment ◽  
Non Gaussian ◽  
Closure Method

Abstract The paper addresses non-Gaussian stationary response of linear single-degree-of-freedom (SDOF) systems subject to a periodic excitation with correlated random amplitude and phase disturbances which are modeled as correlated Gaussian white noise processes. Correlation between amplitude and phase modulation is specified by the cross-correlation coefficient. Numerical results for the second and fourth moment responses are presented. The probability density function of the response is calculated based on the cumulant-neglect closure method. Non-Gaussianity of the response is discussed in terms of the excess factor. The results show that the moment responses generally increase with larger random amplitude disturbance and decrease with larger random phase modulation. The cross-correlation between amplitude and phase disturbances tend to reduce the system moment response. Large relative detuning results in smaller system moment responses. The response may become Gaussian in the sense of up to the fourth moment for sufficiently large relative detuning or random phase disturbances.

scholarly journals CCID: Cross-Correlation Identity Distinction Method for Detecting Shrew DDoS

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Cheng Huang ◽  
Ping Yi ◽  
Futai Zou ◽  
Yao Yao ◽  
Wei Wang ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Transmission Control Protocol ◽  
Denial Of Service ◽  
Gaussian White Noise ◽  
Normal Flow ◽  
Flow Properties ◽  
Data Packets ◽  
Lower Maximum ◽  
The Cross ◽  
The Difference

This study presents a new method for detecting Shrew DDoS (Distributed Denial of Service) attacks and analyzes the characteristics of the Shrew DDoS attack. Shrew DDoS is periodic to be suitable for the server’s TCP (Transmission Control Protocol) timer. It has lower maximum to bypass peak detection. This periodicity makes it distinguishable from normal data packets. By proposing the CCID (Cross-Correlation Identity Distinction) method to distinguish the flow properties, it quantifies the difference between a normal flow and an attack flow. Simultaneously, we calculated the cross-correlation between the attack flow and the normal flow in three different situations. The server can use its own TCP flow timer to construct a periodic attack flow. The cross-correlation between Gaussian white noise and simulated attack flow is less than 0.3. The cross-correlation between single-door function and simulated attack flow is 0.28. The cross-correlation between actual attack flow and simulated attack flow is more than 0.8. This shows that we can quantitatively distinguish the attack effects of different signals. By testing 4 million data, we can prove that it has a certain effect in practice.

A non-stationary stochastic model for periodic excitation with random phase modulation

1995 ◽  
Vol 10 (2) ◽  
pp. 73-81 ◽  
Author(s):  
Zhikun Hou ◽  
Yunshen Zhou ◽  
Mikhail F. Dimentberg ◽  
Mohammad Noori
Keyword(s):  
Stochastic Model ◽  
Phase Modulation ◽  
Random Phase ◽  
Periodic Excitation

OBSERVABILITY OF THE SZ EFFECT MAP'S NON-GAUSSIAN FEATURES

2006 ◽  
Vol 21 (19) ◽  
pp. 1541-1546 ◽  
Author(s):  
LIANG CAO ◽  
YAO-QUAN CHU
Keyword(s):  
Order Statistics ◽  
Fourth Order ◽  
Cross Correlation ◽  
Hot Gas ◽  
Galaxy Distribution ◽  
Cross Correlations ◽  
Wmap Data ◽  
The Cross ◽  
Non Gaussian ◽  
Cmb Fluctuations

We study the high order cross-correlation between the WMAP map and 2MASS galaxy distribution in order to detect the non-Gaussian behaviors of the SZ effect on the CMB fluctuations induced by 2MASS. The 2MASS distribution is significantly non-Gaussian, which is characterized by the fourth order correlations in DWT representation. With an unbiased mock sample we show, if the CMB data contains the information of 2MASS hot gas caused SZ effect, the non-Gaussianity of the cross-correlations between the CMB and 2MASS is observable with the fourth order statistics on scales of clusters. We compared this result with the cross-correlation between the observed WMAP data and 2MASS, finding similar non-Gaussianity to the mock SZ samples. It strongly evidences the existence and observability of the SZ signal in the WMAP data caused by the 2MASS clusters.

scholarly journals Insights to enhance the examination of tool marks in human cartilage

2021 ◽  
Author(s):  
Matthias Weber ◽  
Anja Niehoff ◽  
Markus A. Rothschild
Keyword(s):  
Light Microscope ◽  
Cross Correlation ◽  
Costal Cartilage ◽  
Correlation Coefficients ◽  
Human Cartilage ◽  
Cut Marks ◽  
Tool Marks ◽  
The Cross ◽  
Cleaning Methods ◽  
The Individual

AbstractThis work deals with the examination of tool marks in human cartilage. We compared the effectiveness of several cleaning methods on cut marks in porcine cartilage. The method cleaning by multiple casts achieved the significantly highest scores (P = 0.02). Furthermore, we examined the grain-like elevations (dots) located on casts of cut cartilage. The results of this study suggest that the casting material forms these dots when penetrating cartilage cavities, which are areas where the strong collagen fibres leave space for the chondrocytes. We performed fixation experiments to avoid this, without success. In addition, 31 casting materials were compared regarding contrast under light-microscope and 3D tool marks scanner. Under the light-microscope, brown materials achieved significantly higher values than grey (P = 0.02) or black (P = 0.00) whereas under the 3D scanner, black materials reached higher contrast values than grey (P = 0.04) or brown (P = 0.047). To compare the accuracy and reproducibility of 6 test materials for cartilage, we used 10 knives to create cut marks that were subsequently scanned. During the alignment of the individual signals of each mark, the cross-correlation coefficients (Xmax) and lags (LXmax) were calculated. The signals of the marks in agarose were aligned with significantly fewer lags and achieved significantly higher cross-correlation coefficients compared to all tested materials (both P = 0.00). Moreover, we determined the cross-correlation coefficients (XC) for known-matches (KM) per material. Agarose achieved significantly higher values than AccuTrans®, Clear Ballistics™, and gelatine (all P = 0.00). The results of this work provide valuable insights for the forensic investigation of marks in human costal cartilage.

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