The article introduces a new proposal of a defuzzification method, which can be implemented in fuzzy controllers. The first chapter refers to the origin of fuzzy sets. Next, a modern development based on this theory is presented in the form of ordered fuzzy numbers (OFN). The most important characteristics of ordered fuzzy numbers are also presented. In the following chapter, details about the defuzzification process are given as part of the fuzzy controller model. Then a new method of defuzzification is presented. The method is named center of circles intersection (CCI). The authors compare this method with a similar geometric solution: triangular expanding (TE) and geometric mean (GM). Also, the results are compared with other methods such as center of gravity (COG), first of maxima (FOM) and last of maxima (LOM). The analysis shows that the proposed solution works correctly and provides results for traditional fuzzy numbers as well as directed fuzzy numbers. The last chapter contains a summary, in which more detailed conclusions are provided and further directions of research are indicated.

Defending against DoS (denial of service) attacks has become a great challenge, especially for institutions that provide access to their services in the public network. State-of-the-art identity concealing tools and vast number of computers connected to the network require ensuring appropriate means for entities at risk to enable defence from the particular type of threats. This article presents a concept of user authentication in IP communication. The concept consists in providing the receiver with the possibility to determine sender՚s identity at the Internet layer level. This provides both the capability of defence against DoS attacks and possibility of utilizing the presented model over existing Internet network, which is directly responsible for transmission. The authors hope that the concept is a significant step in the perception of public network data transmission.