[Primena Voronoi-Delone triangulacija i Katalanovih objekata u zaštiti podataka]: doktorske disertacije

This doctoral dissertation is in the field of computer geometry in combination with data protection methods, with an emphasis on the implementation of applications using object-oriented programming techniques. New methods for data protection using Voronoi - Delaunay triangulation were presented. The first method is based on 3D plane encryption in GIS. The second method is based on the authentication of users (clients) of banks, by encrypting the image using the incremental algorithm Voronoi - Delone triangulation and Catalan objects. The third method is the method of steganography, which is based on a combination of Catalan objects and Voronoi - Delone triangulation. The fourth method refers to the proposal of application of one algorithm of computer geometry in the procedure of generating Cryptographic keys from one segment of 3D image

ENCRYPTION OF 3D PLANE IN GIS USING VORONOI-DELAUNAY TRIANGULATIONS AND CATALAN NUMBERS

A method of encryption of the 3D plane in Geographic Information Systems (GIS) is presented. The method is derived using Voronoi-Delaunay triangulation and properties of Catalan numbers. The Voronoi-Delaunay incremental algorithm is presented as one of the most commonly used triangulation techniques for random point selection. In accordance with the multiple applications of Catalan numbers in solving combinatorial problems and their "bit-balanced" characteristic, the process of encrypting and decrypting the coordinates of points using the Lattice Path method (walk on the integer lattice) or LIFO model is given. The triangulation of the plane started using decimal coordinates of a set of given planar points. Afterward, the resulting decimal values of the coordinates are converted to corresponding binary records and the encryption process starts by a random selection of the Catalan key according to the LIFO model. These binary coordinates are again converted into their original decimal values, which enables the process of encrypted triangulation. The original triangulation of the plane can be generated by restarting the triangulation algorithm. Due to its exceptional efficiency in terms of launching programs on various computer architectures and operating systems, Java programming language enables an efficient implementation of our method

Važnost primjene multimedijske aplikacije stvorene prema ADDIE modelu za poučavanje pisanja i čitanja slova

This paper analyzes the impact of multimedia content on success in learning to write and read the letters of the alphabet. For the research purpose and according to the ADDIE model of instructional design, a multimedia application was created for learning to write and read the letters of the alphabet. This paper describes the application interface display, which presents the functions and the parts of the program code. In the focus of the research are the technical possibilities for the use of multimedia application, as well as the impact of its use on the awareness of pupils and teachers on the importance of the introduction of multimedia teaching content. The main research was focused on the effectiveness of learning to write and read the letters of the alphabet and was carried out by comparing the performance of pupils at the end of the school year in two primary schools.U ovom radu ispituje se utjecaj multimedijskoga sadržaja na učenje čitanja i pisanja slova. U svrhu istraživanja izrađena je multimedijska aplikacija za učenje čitanja i pisanja slova, prema ADDIE modelu instrukcijskoga dizajna. U radu je opisana aplikacija prikazom aplikacijskoga sučelja, opisom funkcija i dijelova koda. Istražene su tehničke mogućnosti korištenja multimedijske aplikacije kao i utjecaj njezine uporabe na svijest učenika i nastavnika o važnosti uvođenja multimedijskih nastavnih sadržaja. Glavno se istraživanje odnosi na uspjeh učenja čitanja i pisanja slova, a provedeno je usporedbom postignuća učenika na kraju školske godine u dvije osnovne škole

Comparative analysis of the effects of dalteparin and reviparin on perioperative blood loss in patients with extracapsular hip fractures treated with intramedullary nailing

Aim To determine differences between reviparin and dalteparin treatment in patients with extracapsular hip fractures treated with intramedullary nailing and their effects on perioperative blood loss and early postoperative recovery. Methods Retrospective comparative study included 68 patients with extracapsular hip fracture who were divided into dalteparin and reviparin group. Medical records were used to obtain demographic data, laboratory parameters, haemoglobin and haematocrit levels, platelet count, mortality rate and medical complications. Results Out of total 68 patients, 31 were in reviparin and 37 in dalteparin group. Mean age of patients was 70.5 (±14.4) and 76.8 (±8.4) years in reviparin and dalteparin group, respectively (p=0.071). Median values of haemoglobin levels on the first postoperative day were lower in dalteparin group compared to reviparin group (p=0.012). On the first postoperative day haematocrit values were also lower in dalteparin than in reviparin group (p=0.015). Both groups showed an increase in platelet count on the first postoperative day, but without significant difference (p=0.084). There was no statistically significant difference in intrahospital mortality between the groups (6.4% vs. 2.7%; p=0.588). One case of pulmonary embolism was detected in the dalteparin group. Conclusion Low-molecular-weight heparin is the drug of choice in patients with hip fractures for thromboprophylaxis. Due to non-antithrombin-mediated actions, reviparin and dalteparin could have different effects on perioperative blood loss. Both dalteparin and reviparin are safe and effective agents for thromboprophylaxis in patients with proximal femur fractures

[Primena Voronoi-Delone triangulacija i Katalanovih objekata u zaštiti podataka]: doktorske disertacije

This doctoral dissertation is in the field of computer geometry in combination with data protection methods, with an emphasis on the implementation of applications using object-oriented programming techniques. New methods for data protection using Voronoi - Delaunay triangulation were presented. The first method is based on 3D plane encryption in GIS. The second method is based on the authentication of users (clients) of banks, by encrypting the image using the incremental algorithm Voronoi - Delone triangulation and Catalan objects. The third method is the method of steganography, which is based on a combination of Catalan objects and Voronoi - Delone triangulation. The fourth method refers to the proposal of application of one algorithm of computer geometry in the procedure of generating Cryptographic keys from one segment of 3D image

Application of Delaunay Triangulation and Catalan Objects in Steganography

This paper presents a new method of steganography based on a combination of Catalan objects and Voronoi–Delaunay triangulation. Two segments are described within the proposed method. The first segment describes the process of embedding data and generating a complex stego key. The second segment explains the extraction of a hidden message. The main goal of this paper is to transfer a message via the Internet (or some other medium) using an image so that the image remains absolutely unchanged. In this way, we prevented the potential attacker from noticing some secret message hidden in that picture. Additionally, the complex stego key consists of three completely different parts (the image, the encrypted Delaunay triangulation, and the array Rk in Base64 code), which are very difficult to relate with each other. Finally, a few security analyses of the proposed method are conducted, as well as the corresponding steganalysis