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Rakto apsikeitimo protokolo, kaip ir bet kurio asimetrinės kriptografijos algoritmo, pagrindas yra vienkryptės funkcijos, kurias paprasta apskaičiuoti, tačiau apskaičiuoti atvirkštinę jų reikšmę per priimtiną laiko tarpą neįmanoma. Darbe bus bandoma įrodyti, kad tiriamoji lygčių sistema turi mažai sprendinių ir yra tinkama kriptografiniams algoritmams. Iš pradžių tyrinėta atskiros lygties sprendinių aibė, paskui pereita prie lygčių sistemos sprendinių aibės. Sprendiniai ieškomi naudojant matricų perrinkima, tai pat pasitelkiant kitus metodus. Nustatyta, kad lygčių sistemos sprendinių skaičius, nepriklauso nuo matricos eilės m. / Key agreement protocol, as well as any asymmetric cryptographic algorithm, is based on one-way functions which are easy to calculate, but to calculate the inverse of their value within a reasonable period of time is impossible. The paper will attempt to prove that the system of equations has not much solutions ant that it could be used in cryptographic algorithm. At first individual equation was solved, set of solutions was found. Then moved explore to the set of solutions of equations system. Solutions were found using brute force algorithm for matrices. As well as through other methods. It was found that the number of solutions of equations system does not depend on the matrix size.

The increased use of returnable packaging have given rise to the trend of packaging logistics.The operation of returnable packaging is challenging for global companies due to thecomplexity in the process and information flows. Companies invest in returnable packagingsystems in order to ensure quality throughout the supply chain. Despite the large investments inan returnable packaging fleet, it is often poorly controlled, leading to vast tied-up capital andshrinkage.This thesis proposes how the visibility and control of the system is affected by thecategorization of packaging and the allocation of responsibilities throughout the packaginghandling process. Theoretical and empirical studies were carried out, the theoretical part helpeddefine the problem. A case study were performed at Scania CV AB in Södertälje, Sweden.Results of this study shows that categorization of packaging is not sufficient to attain a suitablelevel of control in an packaging handling process. Although it could be used as a supporting orgoverning documents for standardization in the process. Findings showed that theresponsibilities in the process should be centralized in as large extent as possible. Although ifthe current process is lacking visibility and control, the benefits of centralized control may belost.

Irregular migration is one of our times challenge and the news about migrants dying in the Mediterranean Sea seems to be more and more common these days. African migrants are risking their lives migrating by routes through the desert on trucks packed with migrants to get to Libya; this route is called the back way. From Libya they are crossing the Mediterranean Sea in small over loaded boats with the hope to reach Italy. This study focus on young Gambian men who say that they are prepared to risk their life by going the back way in order to reach Europe. Gambia is a small country in West Africa, a country that has been free from violence and war, a peaceful country. Yet the back way is something that is on everybody’s lips in Gambia today and a lot of people, especially young men, are trying to get to Europe through that way. This research is looking into why these young men are prepared to risk their lives to reach Europe; it is showing what it is that make people take their decisions to go. In order to find answers to this, interviews with young men in Gambia has been done and the material have then been analyzed with the help of the push and pull model, the rational choice theory and Charles Tilly’s ideas about durable inequality. What can be understood from the findings in this research is that people migrate in order to improve their lives. They consider the back way only because that is what is available to them since the legal ways of getting to Europe are few and hard to get for somebody from the developing world. The research also shows that your position in the family and in the society plays a crucial part in the decision of going or not going.

Achieving a higher transmission rate had always been a goal in the field of communications. Having a two-way channel in which two nodes transmit and receive data at the same time, is an important tool to achieve this goal. A two-way channel is the first step from point-to-point communication channel toward multi-user networks. In its ideal form, we can transmit data two times faster by using a perfect two-way channel. However, the area of two-way channels had not been of interest of researchers during the past years and number of articles on this area is considerably low comparing to other types of multi-user communication networks, such as multiple-access channel, broadcast channel and interference channel. On the other hand, use of analog-to-digital converters (ADC) is a must in modern systems to enable us to analyze data faster; nevertheless, presence of ADC add some other difficulties to the system. In this thesis, different scenarios about two-way channel are studied. The Shannon's model of two-way channel and his inner and outer bounds on the capacity of this channel are presented. For the Gaussian Two-Way Channel with quantized output, in which the ambient noise has a Gaussian distribution, the expression of Shannon's inner bound for both Gaussian and discrete inputs are derived. The best uniform quantizer to obtain the maximum achievable rate for Gaussian input is found numerically. Then we will evaluate the additive noise model for the quantizer from an information theoretic point of view. For the discrete input, the method of rotating one input with respect to other one is employed to enlarge the achievable rate region. At last, two scenarios will be studied in which, minimizing the power of interference, does not necessarily maximizes the transmission rate.

In this thesis, I conduct the hardware prototyping of a two-way relay system using the National Instruments FlexRIO hardware platform. First of all, I develop several practical mechanisms to solve the critical synchronization issues of the systems, including Orthogonal Frequency-Division Multiplexing (OFDM) frame synchronization at the receiver, source to source node synchronization, and handshaking between the sources and relay nodes. Those synchronization methods control the behavior of the two source nodes and the relay node, which play critical roles in the two-way relay systems. Secondly, I develop a pilot-based channel estimation scheme and validate it by showing the successful self-interference cancellation for the two-way relay systems. In particular, I experiment the self-interference cancellation technique by using several channel estimation schemes to estimate both source to relay channels and relay to source channels. Moreover, I implement the physical layer of a 5 MHz OFDM scheme for the two-way relay system. Both the transmitter and receiver are designed to mimic the Long Term Evolution (LTE) downlink scenario. The physical layer of the transmitter has been implemented in Field-Programmable Gate Arrays (FPGAs) and executed on the hardware board, which provides high throughput and fundamental building blocks for the two-way relay system. The physical layer of receiver is implemented in the real-time controller, which provides the ?exibility to rapidly recon?gure the system. Finally, I demonstrate that the 5MHz OFDM based two-way relay system can achieve reliable communications, when the channel estimation and system synchronization can be correctly executed.

This thesis explores the nature of public access rights for outdoor recreation in New Zealand. It aims to improve understanding of these rights by examining the New Zealand public policy framework for public access, the social constructions of access rights and the interaction of these dimensions via analysis of two contemporary New Zealand access issues: the foreshore access debate and the state-sponsored Land Access Review. An institutional arrangements framework forms the study�s conceptual basis and is critiqued for its value in the examination of rights of public access. Multiple qualitative methods were employed to collect data, including interviews with access actors, submission analysis, examination of public policy documents and critical interpretation of the access discourse within the mass media. Key themes from the international access literature are identified and the disparate nature of much of this research is highlighted. Within New Zealand, public access represents an area of research neglect. This thesis provides the first comprehensive study of rights of public access for outdoor recreation in New Zealand. A threshold has been reached in the evolution of access rights in New Zealand. Societal changes are perceived to be reducing the public�s traditional rights to access land for outdoor recreation. Owing to the importance of these rights within conceptions of New Zealand national identity, the Government is codifying access rights in a bid to protect them. Thus a shift in access arrangements is occurring, from reliance upon social customs to increasing use of public policy instruments. Access rights are being renegotiated within a highly contested environment. The debate is being staged within the political arena and via the national news media; access has become a significant national issue. As a result, the level of engagement has shifted from localised access transactions between landholders and recreationists, to a national discussion regarding competing rights to land. Access actors have reacted in different ways to the reforms of access arrangements, driven by the manner in which the proposals affect their property rights, social values and norms. Some reactions have been strident and confrontational. Inadequate public policy arrangements for access have created the 'space' for these multiple social constructions of access to develop. Convergence of a disparate and poorly enforced access public policy framework with varying social representations of access rights is influencing the access outcomes. The 'place' of public access within New Zealand society occurs at the intersection of several strongly-held cultural traditions, including private property rights, Maori customary rights, and a belief that it is a birthright to freely access the outdoors. The tension between these values underpins New Zealand�s unique (and changing) manifestation of the rights of the public to access land for recreation.

Bibliography :leaves 144-[148] / xiv, [148] leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1993

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1991. / Includes bibliographical references (last 2 leaves ).

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1993. / Includes bibliographical references (leaves 144-[148]).