Journal of Naval Sciences and Engineering

10

Authors: Hakan UÇAR

Accurate prediction of the vibration responses is an essential requirement during the design and optimization stages of mechanical structures. For this reason, a vibration response prediction (VRP) methodology, based on a set of frequency response functions (FRF) and operational responses, is established. In this methodology, defining the sources and transmission paths of the structure accurately is critical. Since it is based on the FRFs of the system, unconsidered sources and/or missing path result in inaccurate predictions. The goal of this paper is to present the effect of a missing path on the prediction results. In accordance with this purpose, a three degree-of-freedom system will be investigated analytically and VRP methodology will be applied along with the calculated receptances and displacements of the system.

15

Authors: Cengiz ERDÖNMEZ

Meshless methods are became an alternative to most popular numerical methods used to solve engineering problems such as Finite Difference and Finite Element Methods. Because of element free nature, problems are solved using meshless methods depending on the general geometry and conditions of the problem. Mixed Meshless Local Petrov-Galerkin (MLPG) approach is based on writing the local weak forms of PDEs. Moving least squares (MLS) is used as the interpolation schemes. In this study contact analysis problem is modelled using Meshless Finite Volume Method (MFVM) with MLS interpolation and solved for beam contact problem. Meshless discretization and linear complementary equation of the 2-D frictionless contact problems are described first. Then the problem is converted to a linear complementary problem (LCP) and solved using Lemke’s algorithm. An elastic cantilever beam contact to a rigid foundation is considered as an example problem.

18

Authors: Yusuf KAVURUCU, Ömer SEVER

As a solution to fair exchange problem, non-repudiation protocols are being widely used over digital environment. Applications of non-repudiation protocols are spreaded over Electronic Contract Signing, Certified E-mail, electronic payment and e-commerce. In this paper we present a strong fair hybrid non-repudiation protocol which works with all types of pairings. The protocol is modeled with an on-line TTP in the first round and then works optimistic in next rounds. The protocol offers stronger security by integration of Joux tri-partite key exchange and uses certificateless ID based signature and encryption methods. All the cryptographic methods used in the protocol are based on pairing based cryptography which can be implemented on all three types of pairings.

29

Authors: Emrah ERGÜL, Mehmet KARAYEL, Oğuzhan TİMUŞ, Erkan KIYAK

Attribute based approaches are commonly used in recent years instead of low level features for image classification which is one of the most important problems in the field of computer vision. The most important advantage of attribute based approach is that learning can be performed similar to human by using attributes which makes sense for people. In this study, unsupervised attributes are developed in order to avoid human related problems in supervised attribute learning. In our proposed work, the attributes are generated as random binary and relative definitions. The process of random attribute generation simplifies the data modeling when compared to other work in the literature. In addition, a major problem which is the increasing the numbers of attributes in attribute based approaches is eliminated owing to the increasing the numbers of attributes easily. Furthermore, attributes are selected more wisely using simple applicable algorithm to improve the discriminative capacity of randomly generated attribute set for image classification. The proposed approaches are evaluated with the other similar attribute based studies comparatively in the literature based on the same data set (OSR-Open Scene Recognition). Experiments show that noteworthy performance increase is achieved.