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.

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.Keywords: application; e-learning; education; improving learning. --- 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.Ključne riječi: aplikacija; e-učenje; obrazovanje; poboljšavanje nastave.  

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.

: This paper presents the authentication method using the Delaunay triangulation incremental algorithm and the Catalan objects. The proposed method is a combination of computational geometry and cryptography. This method presents a new step towards encoding the triangle coordinates using the Catalan-key. We provided specific suggestions for the application of this method in the authentication for bank clients by the image encryption. Client authentication verification is performed by asking the client to enter the (x,y) coordinate values of randomly selected indices of an array. If the entered coordinates match the index values in the banking system array, then the transaction or other operation is approved. If the matching fails, it means that we have an unidentified person who has followed the whole process and wants to break into the banking system. There are many advantages arising from a scenario for the user authentication by the assigned Catalan object and the stack permutation method. Also, we provided concrete examples for the Delaunay encryption of image with an authentication scenario and experimental results for the proposed method.

In this paper is presented a procedure for the application of one computational geometry algorithm in the process of generating hidden cryptographic keys from one segment of the 3D image. The presented procedure consists of three phases. In the first phase, is done the separation of one segment from the 3D image and determination of triangulation of the separated polygon. In the second phase, is done a conversion from the obtained triangulation of the polygon in the record which represent the Catalan key. In the third phase, the Catalan-key is applied in encryption of text based on the balanced parentheses combinatorial problem.

objective of the study is to analyze the opinion about traditional and online learning methods with respect to course, content, teacher and reachability. Keeping this in view, a software study was conducted and which was aimed to develop the learning tool which is known as "Knowledge Connection" for Sank-Hara Computer Centre for Education and Learning. It is an intranet/internet based learning tool based on blended learning methodology. Pre Hypertext Processor, Apache Web Server and Mysql as the back end and other tools such as Dream weaver were used to create a learning model and SPSS 20 were used to interpret the results. Sample of 100 respondents were taken for the study based on simple random sampling method. The findings reveal that the students are much more interested towards online environment based on their mean value. This study is unique in the sense that new user friendly learning tool have been deployed to test the results. The results will be helpful to introduce more number of online courses which can be incorporated in the syllabus to enrich more knowledge towards knowledge society. KeywordsOnline learning, Knowledge-Connection, Blended learning, Knowledge society

This paper present a way of developing web applications for mobile devices in NetBiscuit platform which is implemented at the University of Novi Pazar. The process of implementation is based on project management of e-learning, more precisely on the application of project management (through four phases: definition, planning, management and evaluation). It's designed the combination of project management phase which enables more efficient planning and performing online education with the procedure of design courses for e-learning. The final part contains the process of integration of mobile web applications with Learning Management System (LMS).

The purpose of this work is the enhancement of performance by a new design of monolithic heat exchangers under steady-state operating conditions. Heat transfer phenomena and hydrodynamics have been studied and visualized by computational fluid dynamics (CFD). Further, a simple gas distribution system has been analyzed in purpose to find best performance of the exchanger. To achieve this, 3D simulations of air flow were performed. One of characteristics of monolithic structures is the low pressure drop and high heat transfer coefficient. This is because they operate in the laminar flow regime and have high compactness. However, some experimental studies show that when two fluids are introduced into monolith channels, the manifolds cause severe pressure losses. Therefore, in this work, turbulent flow regime at low Reynolds numbers has been investigated to find the difference and better understanding of these structures which are of interest in high temperature applications today. The simulation shows that the pressure drop of the gas flow distributor is a key parameter affecting the heat transfer in the exchanger channels. (Less)

Funded by European Community and Swiss government research project AZEP (Advanced Zero Emission Power Plant), the project was carried out at the Department of Energy Sciences at Lund Faculty of Engineering (LTH). The project addressed the development of a specific, zero emissions, gas turbine-based, power generation process to reduce local and global emissions in a cost-effective way. In this project a unique monolith heat and mass exchanger reactor with an oxygen permeable membrane was proposed by the Norsk Hydro Oil and Energy Research Center in Norway. The aim of this thesis is to describe a complete design of a monolithic reactor where both heat and oxygen transport takes place. This led to the development of a mathematical model of an oxygen membrane reactor which fulfils the boundary conditions set by the AZEP process. Further, an investigation of the total pressure drop and pressure distribution of the manifolding system using the Computational Fluid Dynamics (CFD) tool FLUENT was carried out. A further goal was also to perform dynamic analysis of the AZEP reactor. In order to perform such analysis, calculation tools were needed to describe the performance of CO2 capture. The object-oriented programming languages Modelica and Dymola were used to describe dynamic behavior of the oxygen transfer reactor. Sensitivity studies performed with the membrane model showed that a high inlet sweep temperature would raise the magnitude of the oxygen permeation flux through the MCMmembrane. At the same time high inlet air temperatures would be necessary to keep the driving potential through the length of the membrane at a higher level which would be important for achieving the targeted industrial values of oxygen fluxes. The dynamic simulations showed that disturbances on sweep flow had larger impact on the membranes performance than disturbances introduced on the air side of the reactor. By introduction of a new solution of flow manifolds (linear channel arrangement) a less complex header system than the one in the AZEP solution was achieved. Since the implementation of detailed membrane model in heat and mass balance calculations for system studies would result in excessive calculation time, results from this study were utilized for the generation of correlations describing the oxygen transfer as a function of operating parameters such as temperature and partial pressure. This modeling approach was expected to improve the accuracy of the system studies. (Less)

Funded by European Community and Swiss government research project AZEP (Advanced Zero Emission Power Plant), the project was carried out at the Department of Energy Sciences at Lund Faculty of Engineering (LTH). The project addressed the development of a specific, zero emissions, gas turbine-based, power generation process to reduce local and global emissions in a cost-effective way. In this project a unique monolith heat and mass exchanger reactor with an oxygen permeable membrane was proposed by the Norsk Hydro Oil and Energy Research Center in Norway. The aim of this thesis is to describe a complete design of a monolithic reactor where both heat and oxygen transport takes place. This led to the development of a mathematical model of an oxygen membrane reactor which fulfils the boundary conditions set by the AZEP process. Further, an investigation of the total pressure drop and pressure distribution of the manifolding system using the Computational Fluid Dynamics (CFD) tool FLUENT was carried out. A further goal was also to perform dynamic analysis of the AZEP reactor. In order to perform such analysis, calculation tools were needed to describe the performance of CO2 capture. The object-oriented programming languages Modelica and Dymola were used to describe dynamic behavior of the oxygen transfer reactor. Sensitivity studies performed with the membrane model showed that a high inlet sweep temperature would raise the magnitude of the oxygen permeation flux through the MCM membrane. At the same time high inlet air temperatures would be necessary to keep the driving potential through the length of the membrane at a higher level which would be important for achieving the targeted industrial values of oxygen fluxes. The dynamic simulations showed that disturbances on sweep flow had larger impact on the membranes performance than disturbances introduced on the air side of the reactor. By introduction of a new solution of flow manifolds (linear channel arrangement) a less complex header system than the one in the AZEP solution was achieved. Since the implementation of detailed membrane model in heat and mass balance calculations for system studies would result in excessive calculation time, results from this study were utilized for the generation of correlations describing the oxygen transfer as a function of operating parameters such as temperature and partial pressure. This modeling approach was expected to improve the accuracy of the system studies.

The need to reduce CO2 emissions from fossil-fuel based power production creates the need for new power plant solutions where the CO2 is captured and stored or reused. Different concepts to capture CO2 fall into the three main categories: 1. Precombustion decarbonization 2. Oxy-fuel combustion 3. Post-combustion removal of carbon. In the first two types of processes Oxygen Transport Membrane (OTM) is the key component, as pure oxygen is usually required to process reactions (e.g. Integrated Gasification Combined Cycle IGCC, Advanced Zero Emission Plant AZEP). Post-combustion removal processes can for example utilize adsorption/ desorption in certain salt solutions. This paper will describe two different applications of CO2- emission-free processes, one using an OTM, the other a high pressure post combustion removal process, the Sargas process, which has been modeled in a project with Siemens Industrial Turbomachinery AB and Alstom Power Sweden AB. All modeling work was carried out in the modeling language Modelica, which is an open standard for equation-based, object-oriented modeling of physical systems. System models have been built using the CombiPlant library, a modeling library for combined cycle power plants from Modelon AB. (Less)

The need to reduce CO2 emissions from fossil-fuel based power production creates the need for new power plant solutions where the CO 2 is captured and stored or reused. Oxygen Transfer Membrane (OTM) is the key component of oxy-fuel combustion processes as pure oxygen is usually required to process reactions (e.g. Natural Gas Combined cycle NGCC, Pulverised Coal-fired power plants PC-plants, Integrated Gasification Combined Cycle IGCC). The transfer of oxygen across such OTM is limited by a number of processes, such as surface exchange and ambipolar diffusion through mixed-conducting gas separation layer. This paper shows a mathematical model of an oxygen transfer membrane incorporated into OTM reactor (OTM reactor consists of High Temperature Heat Exchanger and OTM), where transient behavior takes place. The modeling of the OTM reactor has been carried out to show the importance of optimizing OTM parameters (temperatures, oxygen partial pressures, oxygen flux) and reactor design that enables a high oxygen transfer for optimum performance of future power cycles with CO2 capture. All modeling work was carried out in the modeling language Modelica, which is an open standard for equation-based, object-oriented modeling of physical systems. The OTM reactor model has been built using the CombiPlant Library, a modeling library for combined cycle power plants which is under development. Copyright (Less)

High-temperature catalytic processes such as partial oxidation of Methane (POX) and steam Methane reforming (SMR) may benefit from use of reactor systems using monolithic honeycomb structures. Hereby, process performance is enhanced through more efficient heat transfer and considerable smaller reactor foot-prints than for conventional reactor concepts. Compact ceramic heat exchange structures may also be an interesting option for increasing the energy efficiency of high temperature processes in general. One example is single cycle turbines where these structures can be used as recuperators. The purpose of this paper is to describe modelling of gas flow pattern and heat transfer in reactors and heat exchangers with monolithic based structures. This technology is currently under development in a partnership of European companies and academia, with financial support from the EC and Swiss Government. The mathematical model developed for heat transfer and flow maldistribution has been used for counter-current checkerboard channelarrangement. Pressure drop has been analyzed both experimentally and numerically (computation fluid dynamics, CFD). Power density has been shown to depend on various reactor parameters. Channel geometry, inlet gas temperature difference and channel wall thickness have been calculated to find the influence on power density. (Less)