Low-density parity-check (LDPC) codes have been shown to have good error correcting performance approaching Shannon’s limit. Good error correcting performance enables efficient and reliable communication. However, a LDPC code decoding algorithm needs to be executed efficiently to meet cost, time, power and bandwidth requirements of target applications. The constructed codes should also meet error rate performance requirements of those applications. Since their rediscovery, there has been much research work on LDPC code construction and implementation. LDPC codes can be designed over a wide space with parameters such as girth, rate and length. There is no unique method of constructing LDPC codes. Existing construction methods are limited in some way in producing good error correcting performing and easily implementable codes for a given rate and length. There is a need to develop methods of constructing codes over a wide range of rates and lengths with good performance and ease of hardware implementability. LDPC code hardware design and implementation depend on the structure of target LDPC code and is also as varied as LDPC matrix designs and constructions. There are several factors to be considered including decoding algorithm computations,processing nodes interconnection network, number of processing nodes, amount of memory, number of quantization bits and decoding delay. All of these issues can be handled in several different ways. This thesis is about construction of LDPC codes and their hardware implementation. LDPC code construction and implementation issues mentioned above are too many to be addressed in one thesis. The main contribution of this thesis is the development of LDPC code construction methods for some classes of structured LDPC codes and techniques for reducing decoding time. We introduce two main methods for constructing structured codes. In the first method, column-weight two LDPC codes are derived from distance graphs. A wide range of girths, rates and lengths are obtained compared to existing methods. The performance and implementation complexity of obtained codes depends on the structure of their corresponding distance graphs. In the second method, a search algorithm based on bit-filing and progressive-edge growth algorithms is introduced for constructing quasi-cyclic LDPC codes. The algorithm can be used to form a distance or Tanner graph of a code. This method could also obtain codes over a wide range of parameters. Cycles of length four are avoided by observing the row-column constraint. Row-column connections observing this condition are searched sequentially or randomly. Although the girth conditions are not sufficient beyond six, larger girths codes were easily obtained especially at low rates. The advantage of this algorithm compared to other methods is its flexibility. It could be used to construct codes for a given rate and length with girths of at least six for any sub-matrix configuration or rearrangement. The code size is also easily varied by increasing or decreasing sub-matrix size. Codes obtained using a sequential search criteria show poor performance at low girths (6 and 8) while random searches result in good performing codes. Quasi-cyclic codes could be implemented in a variety of decoder architectures. One of the many options is the choice of processing nodes interconnect. We show how quasi-cyclic codes processing could be scheduled through a multistage network. Although these net-works have more delay than other modes of communication, they offer more flexibility at a reasonable cost. Banyan and Benes networks are suggested as the most suitable networks. Decoding delay is also one of several issues considered in decoder design and implementation. In this thesis, we overlap check and variable node computations to reduce decoding time. Three techniques are discussed, two of which are introduced in this thesis. The techniques are code matrix permutation, matrix space restriction and sub-matrix row-column scheduling. Matrix permutation rearranges the parity-check matrix such that rows and columns that do not have connections in common are separated. This techniques can be applied to any matrix. Its effectiveness largely depends on the structure of the code. We show that its success also depends on the size of row and column weights. Matrix space restriction is another technique that can be applied to any code and has fixed reduction in time or amount of overlap. Its success depends on the amount of restriction and may be traded with performance loss. The third technique already suggested in literature relies on the internal cyclic structure of sub-matrices to achieve overlapping. The technique is limited to LDPC code matrices in which the number of sub-matrices is equal to row and column weights. We show that it can be applied to other codes with a lager number of sub-matrices than code weights. However, in this case maximum overlap is not guaranteed. We calculate the lower bound on the amount of overlapping. Overlapping could be applied to any sub-matrix configuration of quasi-cyclic codes by arbitrarily choosing the starting rows for processing. Overlapping decoding time depends on inter-iteration waiting times. We show that there are upper bounds on waiting times which depend on the code weights. Waiting times could be further reduced by restricting shifts in identity sub-matrices or using smaller sub-matrices. This overlapping technique can reduce the decoding time by up to 50% compared to conventional message and computation scheduling. Techniques of matrix permutation and space restriction results in decoder architectures that are flexible in LDPC code design in terms of code weights and size. This is due to the fact that with these techniques, rows and columns are processed in sequential order to achieve overlapping. However, in the existing technique, all sub-matrices have to be processed in parallel to achieve overlapping. Parallel processing of all code sub-matrices requires the architecture to have the number of processing units at least equal to the number sub-matrices. Processing units and memory space should therefore be distributed among the sub-matrices according to the sub-matrices arrangement. This leads to high complexity or inflexibility in the decoder architecture. We propose a simple, programmable and high throughput decoder architecture based on matrix permutation and space restriction techniques. / Thesis(Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2007

<p>The non-overlapping clock signal generator circuits are key elements in switched capacitor circuits since non-overlapping clock signals are generally required. Non-overlapping clock signals means signals running at the same frequency and there is a time between the pulses that none of them is high. This time (when both pulses are logic 0) takes place when the pulses are switching from logic 1 to logic 0 or from logic 0 to logic 1. In this thesis this type of clock signal generators are analyzed and designed for different requirements on the switched capacitor (S/C) circuits. Different analytical models for the delay in CMOS inverters are studied. The clock generators for digital circuits based on phase-locked loop and delay-locked loop are also studied. An algorithm, which can automatically size the non-overlapping clock generator circuits, was implemented.</p>

<p>An empirical study of how Malaysian pluralism is understood through Islam Hadhari, Article 11 and the Inter-faith Commission against the backdrop of current Malaysian political and social history, coupled with a theoretical analysis through John Rawls' Political Liberalism, with particular emphasis on the idea of Overlapping Consensus.</p><p>The thesis is an attempt at applying Rawls' theory on the practical case of Malaysia, as a plural society, while at the same time using the practical case of Malaysia to highlight parts of Rawls' own theory.</p>

This work deals with problems where multiple actors simultaneously take control decisions and implement the corresponding actions in large multi-area power systems. The fact that those actions take place in the same transmission grid introduces a coupling between the various decision-making problems. First, transmission constraints involving all actors' controls must be satisfied, while, second, the satisfaction of an actor's operational objective depends, in general, not only on its own actions but on the others' too. Algorithms and/or operational procedures are, thus, developed seeking to reconcile the multiple actors' simultaneous decisions. The confidentiality and operational autonomy of the actors' decision-making procedures are preserved. In particular, two specific problems leading to such a multi-actor situation have been treated. The first is drawn from a recently emerging situation, at least in Europe, where several Transmission System Operators (TSOs) have installed and/or are planning to install Phase Shifting Transformers (PSTs) in such locations in their areas that, by properly adjusting the PST phase angle settings, they can significantly control the power flows entering and exiting their systems. A general framework is proposed for the control of PSTs owned by several TSOs, taking into account their interactions. The proposed solution is the Nash equilibrium of a sequence of optimizations performed by the various TSOs, each of them taking into account the other TSOs' control settings as well as operating constraints relative to the whole system. The method is applied to a linearized network model and illustrated on the IEEE 118-bus system. The second multi-actor situation dealt with in this work stems from the recently increasing amount of discussions and efforts made towards creating the right market structures and operational practices that would facilitate a seamless inter-area trade of electricity throughout large interconnections. In this respect, in accordance with European Union's goal of a fully functional Internal Electricity Market where ideally every consumer will be able to buy electric energy from every producer all across the interconnection, the possibility of every market participant to place its bid in whatever electricity market of an interconnection has been considered. This results in overlapping markets, each with its own schedule of power injections and withdraws, comprising buses all around the interconnection, that are cleared simultaneously by Transaction Schedulers (TSs). An iterative procedure is proposed to reconcile the various TS schedules such that congestion is managed in a fair and efficient way. The procedure converges to such schedules that the various TS market clearings are in a Nash equilibrium. The method is then extended towards several directions: enabling market participants to place their bids simultaneously in more than one TS's market, incorporating $N-1$ security constraints, allowing for joint energy-reserve dispatch, and, accounting for transmission losses. The corresponding iterative algorithms are thoroughly illustrated in detail on a 15-bus as well as the IEEE RTS-96 system.

This thesis consists of three essays, which all concern the dynamics of pension reform. The first essay evaluates the financial balance and the demographic adjustability of the reformed Swedish pay-as-you-go pension system. The main findings are that the demographic adjustability of the system is poor. Furthermore, the financial balance and pension levels are, to a large degree, dependent on the pension fund and its returns. Making some alterations to the system's benefit formula may improve the adjustability of the system, as well as decreasing its pension fund dependency. It is also shown that the new public system imposes an age-dependent implicit tax on labor earnings that is falling with age. Within the pay-as-you-go system, this tax is large for younger workers for whom almost the whole contribution is regarded as a tax. By introducing a public defined contribution system, the total implicit tax may be reduced since the defined contribution system implies a negative implicit tax because savings are subsidized within the defined contribution system. In the second essay a three-generation OLG model for analyzing a privatization of PAYG old-age social security is developed. Furthermore, it proposes an explicit reform for how the privatization transition may be undertaken. The set of government policy instruments is limited to debt issuing and proportional labor income taxation. The possibilities of a Pareto-improving privatization, given the proposed reform, are then analyzed. Contrary to models where a two-generation OLG framework is used, the three-generation framework creates possibilities for a Pareto-improving privatization of old-age social security, since the PAYG system induces a non-optimal implicit tax over the life cycle. By shifting to an optimal tax policy cannot only the pension claims accrued under the PAYG system be financed, but the shift will also be Pareto-improving. In the third essay the performance of the reformed Latvian pay-as-you-go pension system is evaluated against the background of an exceptional projected decrease in the Latvian labor force. The pension system is designed to handle the upcoming difficulties, and special attention has been given in the design to keep the expenditures low relative to the revenues, by introducing rules dampening the increase in the pension expenditures. In the light of the pessimistic projection of the Latvian demography, the newly reformed PAYG system performs remarkably well. The expenditure reducing rules introduced have significant effects on the system's financial balance. The pension reform also includes the launch of a publicly run defined contributions pension system. It is shown that the resulting implicit tax imposed by the public pension system imposes on labor earnings is negative and increasing with age. That is, savings are subsidized in the public pension system. It is also shown that private savings are fully crowded out as individuals try to offset their savings in the pension system. Since individuals are capital constrained, they will have no private assets at all. From a welfare perspective, this suggests the overall contribution rate to the public pension system to be too high. / <p>Diss. Stockholm : Handelshögskolan, 2002</p>

An empirical study of how Malaysian pluralism is understood through Islam Hadhari, Article 11 and the Inter-faith Commission against the backdrop of current Malaysian political and social history, coupled with a theoretical analysis through John Rawls' Political Liberalism, with particular emphasis on the idea of Overlapping Consensus. The thesis is an attempt at applying Rawls' theory on the practical case of Malaysia, as a plural society, while at the same time using the practical case of Malaysia to highlight parts of Rawls' own theory.

The non-overlapping clock signal generator circuits are key elements in switched capacitor circuits since non-overlapping clock signals are generally required. Non-overlapping clock signals means signals running at the same frequency and there is a time between the pulses that none of them is high. This time (when both pulses are logic 0) takes place when the pulses are switching from logic 1 to logic 0 or from logic 0 to logic 1. In this thesis this type of clock signal generators are analyzed and designed for different requirements on the switched capacitor (S/C) circuits. Different analytical models for the delay in CMOS inverters are studied. The clock generators for digital circuits based on phase-locked loop and delay-locked loop are also studied. An algorithm, which can automatically size the non-overlapping clock generator circuits, was implemented.

The aim of this study is to analyse the impacts of the social security system reform performed in Turkey within the

Systemic Lupus Erythematosus (SLE) is a complex autoimmune disease. HTLV-1 Related Endogenous Sequence (HRES-1), a human endogenous retrovirus, produces 2 retroviral-like Gag capsid proteins (p8 and p15) that share significant sequence homology to the U1-subunit of the small ribonucleoprotein complex (U1sn-RNP), an autoantigen of lupus. The central hypothesis is that molecular mimicry between HRES-1 and U1sn-RNP serves as a priming event in SLE via the production of cross-reactive autoantibodies. Anti-HRES-1/U1sn-RNP serological responses in subjects with SLE and comparison populations were characterized. An overlapping peptide set mapping the HRES-1 p8 and p15 proteins was used. SLE subjects produce IgG to several regions of HRES-1. Healthy subjects or those with RA, HIV-1 infection, or HTLV-1-infection produced no significant anti-HRES-1 IgG. Anti-HRES-1 antibodies deposited in the kidneys of patients with SLE glomerulonephritis were identified. Our data suggests that HRES-1 plays a role in SLE by means of a molecular mimicry mechanism with U1sn-RNP.

This work presents a new implementation of the QP algorithm, a computer method to diagonalize the extremely large matrices arising in multimode vibronic problems. Benchmark calculations are included, showing the accuracy of the program. The QP algorithm is extended to treat multiple electronic surfaces for competitive control and this is demonstrated with an Hamiltonian including three electronic states, a model of the benzene radical cation. Finally, the evolution of zeroth-order states in a simple two electronic states, two dimensional model with a conical intersection is explored, towards building a time-dependent view of overlapping resonances coherent control.