No description available.

No description available.

No description available.

Many pavement subgrades in Virginia consist of wet, highly plastic clay or other troublesome soils. Such soils can be treated with traditional lime and cement stabilization methods. Alternatives, including lignosulfonates and polymers, are available, but their performance record is mixed and solid engineering data is lacking, which prevents reliable design. The goal of this research was to screen a suite of traditional and non-traditional stabilizers against three Virginia soils that have caused problems during construction or resulted in poor performance in service. The selected stabilizers were: quicklime, hydrated lime, pelletized lime, cement, lignosulfonate, synthetic polymer, magnesium chloride, and a proprietary cementitious stabilizer. A laboratory procedure was developed and applied to three Virginia soils obtained from Northern Virginia, Staunton, and Lynchburg. Key findings from the research include that (1) traditional lime and cement stabilizers were far more effective than liquid stabilizers (lignosulfonate, synthetic polymer, and magnesium chloride) in increasing strength, (2) the liquid stabilizers were ineffective on soils with high moisture content, (3) the proprietary cementitious stabilizer was more effective in increasing strength than lime for all cases tested, but not was not as effective as the cement stabilizer, (4) quicklime and hydrated lime increased workability of the soils although they did not produce strengths comparable to cement, (5) the strength of soils stabilized with cement and the proprietary cementitious stabilizer can be estimated based on the water-amendment ratio of the mixture, and (6) the strength of soils stabilized with lime can be estimated based on a combination of plasticity index and water-amendment ratio of the mixture. / Master of Science

Self-stabilizing system is a concept of fault-tolerance in distributed computing. A distributed algorithm is self-stabilizing if, starting from an arbitrary state, it is guaranteed to converge to a legal state in a finite number of states and remains in a legal set of states thereafter. The property of self-stabilization enables a distributed algorithm to recover from a transient fault regardless of its objective. Moreover, a self-stabilizing algorithm does not have to be initialized as it eventually starts to behave correctly. In this thesis, we focus on extensions and refinements of self-stabilization by studying two non-traditional aspects of self-stabilization. In traditional self-stabilizing distributed systems [13], the inherent assumption is that all processes run predefined programs mandated by an external agency which is the owner or the administrator of the entire system. The model works fine for solving problems when processes cooperate with one another, with a global goal. In modern times it is quite common to have a distributed system spanning over multiple administrative domains, and processes have selfish motives to optimize their own pay- off. Maximizing individual payoffs under the umbrella of stabilization characterizes the notion of selfish stabilization . We investigate the impact of selfishness on the existence and the complexity of stabilizing solutions to specific problems in this thesis. Our model of selfishness centers on a graph where the set of nodes is divided into subsets of distinct colors, each having their own unique perception of the edge costs. We study the problems of constructing a rooted shortest path tree and a maximum flow tree on this model, and demonstrate that when processes are selfish, there is no guarantee that a solution will exist. We demonstrate that the complexity of determining the existence of a stabilizing solution is NP-complete, carefully characterize a fraction of such cases, and propose the construction of stabilizing solutions wherever such solutions are feasible. Fault containment and system availability are important issues in today's distributed systems. In this thesis, we show how fault-containment can be added to weakly stabilizing distributed systems. We present solutions using a randomized scheduler, and illustrate techniques to bias the random schedules so that the system recovers from all single faults in a time independent of the size of the system, and the effect of the failure is contained within constant distance from the faulty node with high probability (this probability can be controlled by a user defined tuning parameter). Using this technique, we solve two problems: one is the persistent-bit problem, and the other is the leader election problem.

Thesis (Ph. D.)--Northwestern University, 1986. / Typescript. Includes bibliographical references (p. 312-326).

Thesis (doctoral)--Johannes Gutenberg-Universität Mainz, 2004--T.p. verso. / Includes bibliographical references.

This report, rooted in the conflict over the control of natural resource wealth, departs from the widely-accepted findings of two disparate literatures. First, while recent analyses correctly conclude that natural resources rents play a contingent role in development, this study deviates from the conventional wisdom attributing the variation of the resource curse to formal institutions. Secondly, as opposed to the recent wave of “political insurance” arguments that ascribe the creation of reforms to weak incumbents attempting to tie the hands of their successors, I argue that actors pursue similar institutional reforms for economic and political reasons. I build on these literatures by examining the commitment to a specific government institution—stabilization funds, which manage the fluctuations of natural resource rents and stop natural resource wealth from being a curse—across three natural resource-rich Latin American countries: Chile, Mexico and Venezuela. Paradoxically, because successful stabilization funds provide greater political benefits when rents are saved, I argue that these institutions only tie the hands of political successors from using rents for political purposes when they are created for economic purposes. / text

[pt] O objetivo principal do trabalho é avaliar as vantagens e desvantagens associadas à utilização, no âmbito de uma pequena economia aberta, de um mecanismo de intervenção sobre variações dos preços relativos domésticos de insumos intermediários comerciáveis. Esse mecanismo pode ser implementado por meio de uma combinação de tributos e subsídios às importações e exportações dos insumos comerciáveis, com alíquotas variáveis ao longo do tempo. Tal intervenção assume o papel de um instrumento auxiliar de estabilização que, ao ser manejado de forma coordenada com a taxa de juros nominal e os demais instrumentos convencionais de política monetária, pode vir a melhorar a resposta da economia aos choques que a atingem. Um exemplo concreto desse tipo de mecanismo é a CIDE (Contribuição de Intervenção sobre o Domínio Econômico), que tinha entre seus intuitos originais impedir que a volatilidade do preço do petróleo no mercado internacional se transmitisse integralmente aos preços domésticos dos derivados. O trabalho, portanto, destina-se a analisar e responder as seguintes questões: (i) determinar as circunstâncias nas quais a intervenção sobre os preços internacionais dos insumos pode se somar à manipulação da taxa de juros nominal na tentativa de melhor estabilizar a economia; (ii) investigar a natureza da intervenção ótima, ou seja, como o instrumento auxiliar e a taxa de juros nominal devem se movimentar conjuntamente em resposta aos choques; e (iii) medir os ganhos de bem estar que advêm da disponibilidade desse instrumento auxiliar de estabilização. / [en] The main purpose of the current work is to evaluate the advantages and disadvantages of using a mechanism which intervenes in domestic relative prices of tradable intermediate goods. Such a mechanism can be implemented by a combination of taxes and subsidies to imports and exports of tradable intermediate goods, with rates that vary over time. This intervention performs as an auxiliary stabilization instrument that is managed in a coordinated fashion with more conventional ones, such as the nominal interest rate. In the end this work will look into the matters of (i) investigating the circumstances under which the intervention in international commodity prices, together with the nominal interest rate, might help in the task of stabilizing the economy; (ii) determining the optimal response of the available instruments to the shocks that hit the economy; and (iii) measuring the welfare consequences of the availability of this auxiliary stabilization instrument.

Thesis (master's)--Pontifícia Universidade Católica do Rio de Janeiro, 1988. / Abstract in English. Includes bibliographical references (p. 131-140).