SENATUS: An Approach to Joint Traffic Anomaly Detection and Root Cause Analysis

In this paper, we propose a novel approach, called SENATUS, for joint traffic anomaly detection and root-cause analysis. Inspired from the concept of a senate, the key idea of the proposed approach is divided into three stages: election, voting and decision. At the election stage, a small number of \nop{traffic flow sets (termed as senator flows)}senator flows are chosen\nop{, which are used} to represent approximately the total (usually huge) set of traffic flows. In the voting stage, anomaly detection is applied on the senator flows and the detected anomalies are correlated to identify the most possible anomalous time bins. Finally in the decision stage, a machine learning technique is applied to the senator flows of each anomalous time bin to find the root cause of the anomalies. We evaluate SENATUS using traffic traces collected from the Pan European network, GEANT, and compare against another approach which detects anomalies using lossless compression of traffic histograms. We show the effectiveness of SENATUS in diagnosing anomaly types: network scans and DoS/DDoS attacks

Slurry Test Evaluation for In-Situ Remediation of TCE Contaminated Aquifer

Trichloroethylene (TCE) is the most commonly found groundwater pollutant. The focus of this research was to determine the effectiveness of chemical oxidation for in-situ remediation of TCE contaminated aquifers. Analytical techniques were developed to measure the concentration of TCE and its degradation products in soil and in solution. Slurry tests were conducted to emulate in situ conditions. Various media used for the slurry tests included sand, silica and glass beads. In-situ chemical oxidation of the TCE was performed using sodium persulfate (Na2S2O8), Fenton’s reagent, Ozone and sodium persulfate activated by iron, ozone and zero valent iron. Persulfate oxidation was shown to be effective for TCE oxidation in the presence of all the media tested in slurry tests for various molar ratios of oxidant and catalyst (Fe). Approximately 75% of TCE destruction takes place in the first 5 minutes of the slurry test and 90% destruction within 24 hours. Fenton’s oxidation was tried with varying concentration of H2O2 and slurry volume. Percent removal of TCE decreased from a hydrogen peroxide concentration of 3.34% to 5% (w/v). It was found that persulfate oxidation activated by zero valent iron removed TCE more effectively than persulfate oxidation activated by ferrous iron. For persulfate oxidation activated by ozone it was found that 95% of TCE was destroyed at persulfate/TCE molar concentration of 10/1 with an initial rate constant of 0.2854/min. It was also found that increasing the amount of solids in the slurry test decreased the effectiveness of chemical oxidation

CFD EVALUATION OF COUNTER-FLOWING WALL JET

Counter-flowing wall jets are used as mixing devices in several industrial engineering applications, for instance; mixing of effluents in rivers, enhancement of the heat transfer from the walls, etc. Although some experimental and numerical studies have been carried out to analyze the characteristics of counter-flowing wall jets, the internal turbulence structure is yet to be understood. An analysis of the dynamics of the turbulent structures would aid in the characterization of turbulent dissipation in the counter-flowing wall jet flow field. In this study, a counter-flowing wall jet issuing into a main flow is numerically investigated using a three-dimensional, unsteady, Improved Delayed Detached Eddy Simulation for a velocity ratio (jet to main flow) of 5:1. The results of the simulation are validated with available experimental data and are presented with pertinent discussions. The interaction of the jet with the wall and the main flow results in the oscillation of the stagnation point and generates significant turbulence. The feedback mechanism between the stagnation region and the shear layer of the counter-flowing wall jet is analysed by examining the instantaneous flow field. To describe the internal structure of turbulence, the coherent structures within the flow are identified using a vortex identification criterion. These structures are also quantitatively evaluated using proper orthogonal decomposition (POD). The dynamics of the organized structures reveal the complexity of the turbulence in the counter-flowing wall jet flow field

Investigation of projectile coherence effects in fully differential studies of 75 keV proton - H₂ collisions

Fully differential cross sections (FDCS) have been measured for single ionization of H2 by 75 keV proton impact with varying transverse coherence length of the projectiles. As reported in recent years, the scattering angle dependence of the doubly differential cross sections (DDCS) are significantly affected by the projectile coherence properties. The interference structures were observed for the coherent beam, however were absent for an incoherent beam. Interestingly, the FDCS measurements for fixed momentum transfer do not suggest significant differences between the coherent and incoherent cross sections. However, for the FDCS with fixed recoil-ion momentum, clear differences between the two has been established. This suggests that the momentum-transfer vector determines the phase angle in the interference term, which is the ratio between coherent and incoherent cross sections. Earlier, the phase angle entering in molecular two-center interference was believed to be determined by the recoil-ion momentum vector. Recently, a theoretical study was reported which acknowledges that the measured DDCS mentioned above are affected by projectile coherence effects, however, suggests that this should not be seen as wave-packet (de)coherence effect. While our data do not disprove this assertion entirely, this theoretical analysis did not pass an experimental test proposed by its authors and performed within the research project for this thesis --Abstract, page iv