Journal of Naval Sciences and Engineering

11

Authors: Georgios KAKAVELAKIS

Abusive network traffic—to include unsolicited e-mail, malware propagation, and denial-of-service attacks—remains a constant problem in the Internet. Despite extensive research in, and subsequent deployment of, abusive-traffic-detection infrastructure, none of the available techniques addresses the problem effectively or completely. The fundamental failing of existing methods is that spammers and attack perpetrators rapidly adapt to and circumvent new mitigation techniques. Within this framework, we develop a real-time, online system that integrates transport layer characteristics into the existing SpamAssasin tool for detecting unsolicited commercial e-mail (spam).

16

Authors: Hakan UÇAR

The development of sophisticated detection systems threatens to reduce the mission effectiveness of weapon platforms. Therefore, increasing survivability by reducing detectability has become very important subject for the designers giving deep attention to methods of reducing detectability. As far as radar signature is concerned, there are four basic techniques for radar cross section reduction (RCSR); shaping, radar absorbing materials, passive cancellation and active cancellation. Of the four, the use of shaping and radar absorbers are the most effective. Shaping is typically available only for systems still in the design stage, because it can seldom be exploited for vehicles already in production. We can use radar absorbing materials where shaping is not efficient alone. Active cancellation seems to be the most effective for low-frequency RCSR, where use of absorber and shaping become very difficult. Reduction methods tend to be narrowband and effective only over limited spatial regions. The methods must be chosen based on the platform’s missions and expected threats. Although we focus on the radar signature in this paper, we must also consider the other signatures (e.g., infrared, acoustic, magnetic, optical) and balance all signatures and threats for signature control.

21

Authors: Güzide Öncü E. PEKTAŞ, Mustafa KARADENİZ, Nuh Mehmet ÜNVER

Group buying websites have emerged as a new buying trend in online shopping business. It is known as opportunity sites in Turkish literate. One thing is clear: these sites have become a “global phenomenon”. Opportunity sites negotiate deals with local merchants and assure to deliver crowds of customers in exchange for deep discounts. The aim of this paper is to explain how we reach to this technology (from electricity to opportunity sites). How often people visit or make purchase from these sites. What and how much they buy from these sites. Make a factor analysis about consumer’s “needs and the perception of artificial scarcity”, “low price perception”, “innovation” and “feeling privileged”. Whether opportunity sites shopping attitude has a realitonship with factors and demographic features.