Knowledge of the phase space density distribution in details is useful to understand subsequent evolution of the charged particle beam in a transport line.This makes the beam tomography very useful in the application ...Knowledge of the phase space density distribution in details is useful to understand subsequent evolution of the charged particle beam in a transport line.This makes the beam tomography very useful in the application for beam diagnostics.This application is not limited by the beam energy,as opposed to the emittance scanner.This paper presented the simulations and measurements we undertook in TRIUMF beam-lines to validate the maximum entropy(MENT)technique for the tomographic reconstruction of beam density distribution in the 2-dimensional transverse phase space.Beam profiles were taken with a single wire scanner while changing an upstream quadrupole’s strength.Moreover,the phase space plots were directly measured with emittance scanner.A close comparison was made on the resulting phase space density distribution and the emittance value at the same location of the beam-line.They show good agreement.展开更多
HTTP-flooding attack disables the victimized web server by sending a large number of HTTP Get requests.Recent research tends to detect HTTP-flooding with the anomaly-based approaches,which detect the HTTP-flooding by ...HTTP-flooding attack disables the victimized web server by sending a large number of HTTP Get requests.Recent research tends to detect HTTP-flooding with the anomaly-based approaches,which detect the HTTP-flooding by modeling the behavior of normal web surfers.However,most of the existing anomaly-based detection approaches usually cannot filter the web-crawling traces from unknown searching bots mixed in normal web browsing logs.These web-crawling traces can bias the base-line profile of anomaly-based schemes in their training phase,and further degrade their detection performance.This paper proposes a novel web-crawling tracestolerated method to build baseline profile,and designs a new anomaly-based HTTP-flooding detection scheme(abbr.HTTP-sCAN).The simulation results show that HTTP-sCAN is immune to the interferences of unknown webcrawling traces,and can detect all HTTPflooding attacks.展开更多
文摘Knowledge of the phase space density distribution in details is useful to understand subsequent evolution of the charged particle beam in a transport line.This makes the beam tomography very useful in the application for beam diagnostics.This application is not limited by the beam energy,as opposed to the emittance scanner.This paper presented the simulations and measurements we undertook in TRIUMF beam-lines to validate the maximum entropy(MENT)technique for the tomographic reconstruction of beam density distribution in the 2-dimensional transverse phase space.Beam profiles were taken with a single wire scanner while changing an upstream quadrupole’s strength.Moreover,the phase space plots were directly measured with emittance scanner.A close comparison was made on the resulting phase space density distribution and the emittance value at the same location of the beam-line.They show good agreement.
基金supported by National Key Basic Research Program of China(973 program)under Grant No.2012CB315905National Natural Science Foundation of China under grants 61172048,61100184,60932005 and 61201128the Fundamental Research Funds for the Central Universities under Grant No ZYGX2011J007
文摘HTTP-flooding attack disables the victimized web server by sending a large number of HTTP Get requests.Recent research tends to detect HTTP-flooding with the anomaly-based approaches,which detect the HTTP-flooding by modeling the behavior of normal web surfers.However,most of the existing anomaly-based detection approaches usually cannot filter the web-crawling traces from unknown searching bots mixed in normal web browsing logs.These web-crawling traces can bias the base-line profile of anomaly-based schemes in their training phase,and further degrade their detection performance.This paper proposes a novel web-crawling tracestolerated method to build baseline profile,and designs a new anomaly-based HTTP-flooding detection scheme(abbr.HTTP-sCAN).The simulation results show that HTTP-sCAN is immune to the interferences of unknown webcrawling traces,and can detect all HTTPflooding attacks.
