The Artificial Immune System (AIS) is introduced briefly, then as one of the main algorithms in AIS, negative selection algorithm is discussed. In order to reduce the number of holes which is inevitable in negative se...
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The Artificial Immune System (AIS) is introduced briefly, then as one of the main algorithms in AIS, negative selection algorithm is discussed. In order to reduce the number of holes which is inevitable in negative selection algorithm, an algorithm of r-adjustable negative selection algorithm is put forward. The new algorithm can reduce the number of holes through adjusting threshold of matching. The simulation results show that both the number of iteration to generate mature detector and the number of holes decline quickly, while the rate of detecting abnormity raises.
SYN flooding attack is a common method employed in denial of service (DoS) and distributed denial of service (DDoS). It's hard to maintain the effective defense merely by passive defense measures such as monitorin...
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SYN flooding attack is a common method employed in denial of service (DoS) and distributed denial of service (DDoS). It's hard to maintain the effective defense merely by passive defense measures such as monitoring and filtering. To avoid influencing the legitimate service requests and stop attacks at the source, the attack-detection and service-protection must be combined with the trace of the attack source. Having studied and concluded the features of such attacks, we propose a few key metrics to judge if an attack is undergoing. In this paper, the based platform, network measurement system (NMS) is outlined first. Then the detection method is discussed in detail, focusing on the features of service-protection, attack-elimination, and how to trace back the attack source. Finally, we present the experiments of the defending mechanism and analyze their results.
One of the most serious problems encountered in Naval steam plants following World War II was the unreliable performance of boiler and main feedpump pneumatic control systems. In addition to control component and syst...
One of the most serious problems encountered in Naval steam plants following World War II was the unreliable performance of boiler and main feedpump pneumatic control systems. In addition to control component and system design deficiencies, these control systems suffered from inadequate methods to measure and adjust system alignment. This paper describes the development of a set of procedures for on-line alignment verification (OLV) of pneumatic main boiler and feedpump control systems. The procedures are designed for use by N avy control system technicians and, in addition to on-line alignment verification, provide guidance for troubleshooting and for performing system alignment. Procedure static checks measure steady state steaming performance and OLV procedure dynamic checks measure the ability of the boiler and control systems to respond to load changes. The paper describes typical control system characteristics that influence OLV procedure content and the supporting analysis that was used to establish alignment criteria ranges that satisfy both steady state and transient performance requirements. Also described is the alignment criteria tolerance analysis along with the steps involved in a typical OLV check procedure development. Descriptions of the various OLV checks, troubleshooting procedures and alignment procedures are provided. Typical shipboard implementation requirements are described and experience to date with the procedures is provided along with a status report on OLV procedure implementations.
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