Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 313-327). Also available in electronic version.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 106-108).

"Final report for research project sponsored by Northeast Utilities Service Company, Public Service Electric and Gas Company, Yankee Atomic Electric Company under the M.I.T. Energy Laboratory Electric Utility Program."

Decreasing power consumption in small devices such as handhelds, cell phones and high-performance processors is now one of the most critical design concerns. On-chip cache memories dominate the chip area in microprocessors and thus arises the need for power efficient cache memories. Cache is the simplest cost effective method to attain high speed memory hierarchy and, its performance is extremely critical for high speed computers. Cache is used by the microprocessor for channeling the performance gap between processor and main memory (RAM) hence the memory bandwidth is frequently a bottleneck which can affect the peak throughput significantly. In the design of any cache system, the tradeoffs of area/cost, performance, power consumption, and thermal management must be taken into consideration. Previous work has mainly concentrated on performance and area/cost constraints. More recent works have focused on low power design especially for portable devices and media-processing systems, however fewer research has been done on the relationship between heat management, Leakage power and cost per die. Lately, the focus of power dissipation in the new generations of microprocessors has shifted from dynamic power to idle power, a previously underestimated form of power loss that causes battery charge to drain and shutdown too early due the waste of energy. The problem has been aggravated by the aggressive scaling of process; device level method used originally by designers to enhance performance, conserve dissipation and reduces the sizes of digital circuits that are increasingly condensed. This dissertation studies the impact of hotspots, in the cache memory, on leakage consumption and microprocessor reliability and durability. The work will first prove that by eliminating hotspots in the cache memory, leakage power will be reduced and therefore, the reliability will be improved. The second technique studied is data quality management that improves the quality of the data stored in the cache to reduce power consumption. The initial work done on this subject focuses on the type of data that increases leakage consumption and ways to manage without impacting the performance of the microprocessor. The second phase of the project focuses on managing the data storage in different blocks of the cache to smooth the leakage power as well as dynamic power consumption. The last technique is a voltage controlled cache to reduce the leakage consumption of the cache while in execution and even in idle state. Two blocks of the 4-way set associative cache go through a voltage regulator before getting to the voltage well, and the other two are directly connected to the voltage well. The idea behind this technique is to use the replacement algorithm information to increase or decrease voltage of the two blocks depending on the need of the information stored on them.

An attempt is made in this thesis to study some stochastic models of both reliability and inventory systems with reference to the following aspects: (i) the confidence limits with the introduction of common-cause failures. (ii) the Erlangian repair time distributions. (iii) the product interactions and demand interactions. (iv) the products are perishable. This thesis contains six chapters. Chaper 1 is introductory in nature and gives a review of the literature and the techniques used in the analysis of reliability systems. Chapter 2 is a study of component common-cause failure systems. Such failures may greatly reduce the reliability indices. Two models of such systems (series and parallel) have been studied in this chapter. The expressions such as, reliability, availability and expected number of repairs have been obtained. The confidence limits for the steady state availability of these two systems have also been obtained. A numerical example illustrates the results. A 100 (1 - a) % confidence limit for the steady state availability of a two unit hot and warm standby system has been studied, when the failure of an online unit is constant and the repair time of a failed unit is Erlangian. The general introduction of various inventory systems and the techniques used in the analysis of such systems have been explained in chapter 4. Chapter 5 provides two models of two component continuous review inventory systems. Here we assume that demand occurs according to a poisson process and that a demand can be satisfied only if both the components are available in inventory. Back-orders are not permitted. The two components are bought from outside suppliers and are replenished according to (s, S) policy. In model 1 we assume that the lead-time of the components follow an exponential distribution. By identifying the inventory level as a Markov process, a system of difference-differential equations at any time and the steady-state for the state of inventory level are obtained. Tn model 2 we assume that the lead-time distribution of one product is arbitrary and the other is exponential. Identifying the underlying process as a semi-regenerative process we find the stationary distribution of the inventory level. For both these models, we find out the performance measures such as the mean stationary rate of the number of lost demands, the demands satisfied and the reorders made. Numerical examples for the two models are also considered. Chaper 6 is devoted to the study of a two perishable product inventory model in which the products are substitutable. The perishable rates of product 1 and product 2 are two different constants. Demand for product 1 and product 2 follow two independent Poisson processes. For replenishment of product 1 (s, S) ordering policy is followed and the associated lead-time is arbitrary. Replenishment of product 2 is instantaneous. A demand for product 1 which occurs during its stock-out period can be substituted by product 2 with some probability. Expressions are derived for the stationary distribution of the inventor}' level by identifying the underlying stochastic process as a semi-regenerative process. An expression for the expected profit rate is obtained. A numerical illustration is provided and an optimal reordering level maximising the profit rate is also studied. To sum up, this thesis is an effort to improve the state the of art of (i) complex reliability systems and their estimation study (ii) muitiproduct inventory systems. The salient features of the thesis are: (i) Analysis of a two-component reliability system with common-cause failures. (ii) Estimation study of a complex system in which the repair time for both hot standby and warm standby systems are assumed to be Eriangian. (iii) A multi-product continuous review inventory system with product interaction, with a (s, S) policy. (iv) Introduction of the concept of substitutability for products. (v) Derivation of expressions for various statistical measures. (vi) Effective use of the regeneration point technique in deriving various measures for both reliability and inventory systems. (vii) Illustration of the various results by extensive numerical work. (vii) Consideration of relevant optimization problems. / Mathematical Sciences / PhD (Statistics)

This work examines the use of ambiguous or obfuscating narrative devices in 3 works by 20th century Russian authors: A Dead Man’s Memoir, by Mikhail Bulgakov, The Eye by Vladimir Nabokov, and You and I, by Abram Tertz. Bulgakov relies on diabolical imagery as well as characters that are by and large caricatures of how any decent person would behave. Nabokov employs several modernist tropes including skillful use of estrangement, as well as a bland tone towards occurrences that ordinary people would find miraculous. Tertz plays on the notion of a double identity by psychically linking two polar extremes until they are nearly unable to tell themselves apart from one another, causing one to crack and kill himself, thus restoring his observer to a more enlightened state. Each work uses the idea of narrative ambiguity and unreliability to demonstrate the incommunicability of one’s artistic vision in its purest, platonic form.

No description available.

abstract: Memories play an integral role in today's advanced ICs. Technology scaling has enabled high density designs at the price paid for impact due to variability and reliability. It is imperative to have accurate methods to measure and extract the variability in the SRAM cell to produce accurate reliability projections for future technologies. This work presents a novel test measurement and extraction technique which is non-invasive to the actual operation of the SRAM memory array. The salient features of this work include i) A single ended SRAM test structure with no disturbance to SRAM operations ii) a convenient test procedure that only requires quasi-static control of external voltages iii) non-iterative method that extracts the VTH variation of each transistor from eight independent switch point measurements. With the present day technology scaling, in addition to the variability with the process, there is also the impact of other aging mechanisms which become dominant. The various aging mechanisms like Negative Bias Temperature Instability (NBTI), Channel Hot Carrier (CHC) and Time Dependent Dielectric Breakdown (TDDB) are critical in the present day nano-scale technology nodes. In this work, we focus on the impact of NBTI due to aging in the SRAM cell and have used Trapping/De-Trapping theory based log(t) model to explain the shift in threshold voltage VTH. The aging section focuses on the following i) Impact of Statistical aging in PMOS device due to NBTI dominates the temporal shift of SRAM cell ii) Besides static variations , shifting in VTH demands increased guard-banding margins in design stage iii) Aging statistics remain constant during the shift, presenting a secondary effect in aging prediction. iv) We have investigated to see if the aging mechanism can be used as a compensation technique to reduce mismatch due to process variations. Finally, the entire test setup has been tested in SPICE and also validated with silicon and the results are presented. The method also facilitates the study of design metrics such as static, read and write noise margins and also the data retention voltage and thus help designers to improve the cell stability of SRAM. / Dissertation/Thesis / M.S. Electrical Engineering 2013

[pt] Discutimos a determinação da confiabilidade de sistemas eletrônicos. Consideramos como sistemas típicos os teclados eletrônicos pois estes combinam simplicidade e abrangência. Apresentamos métodos de determinação dos parâmetros de confiabilidade a nível de componentes e sistemas, bem como a utilização de modelos matemáticos extraídos da teoria da confiabilidade. Descrevemos os equipamentos projetados para a coleta de dados. Apresentamos resultados práticos que implicam em aumento da confiabilidade dos sistema produzidos. / [en] We discuss the evaluation of the reliability of eletronic systems. We use eletronic keyboards as a typical eletronic system, as they are simple enough to make the propposal practical while still covering a wide field. We presented methods of determination of reliability parameters of components and systems, through the use of mathematical models from reliability theory. We describe the design of specific data aquisition equipments. We present practical results lending to the enhancement of the reliability of the manufactured systems.

M.Ing. / Ever since man had invented the wheel, or for that matter any of his first hand tools, he had a definite need to maintain that object. Man did not have any means to predict failures and he had no idea of how to prevent them. He could not plan for these failures and would not know what material and resources to have on hand. He was obviously restricted to a very primitive and elementary form of breakdown maintenance or a sort of run to break strategy as we would call that in modern maintenance terms. His success could only be measured in terms of the time to the next failure. Due to the nonexistence of engineering standards, the large standard deviation in mean time between maintenance (MTBF) values would render these same values rather useless for predictive purposes. This situation restricted our forefathers to a very reactive approach to maintenance. The astonishing present levels of sophistication in man's skills, engineering design and manufacturing came about through revolution and evolution. This indicates a huge amount of change that has taken place over the years and is still taking place today. As the world is in a constant state of change no business organization can escape the effects of operating m a continually evolving landscape. The very forces of change come about typically through industrial globalization, technological advance, political upheaval, the opening up of new markets and the changing expectations of customers that become more knowledgeable and demanding. For any business to respond to customer needs in a satisfactory manner, that business will have to be highly dependent on logistics. As logistics is a major contributor to life cycle cost (Blanchard, 1992: 70-84) and therefor impacts directly on profit margins, there is a growing need for more effective and efficient management of an organization's resources. Logistic support for any organization or plant is a major consideration in the early design stages of any system or organization or plant. From a logistic support perspective it becomes therefor necessary to assure the effective and economical support of a system, organization or plant throughout its programmed life cycle. One of the most important logistic support elements is maintenance. A lot has been said and written about maintenance. A number of well known philosophies and procedures (Blanchard, 1992: 9-25) such as 'planned preventive maintenance' (PPM), `condition based monitoring' (CBM), 'reliability centered maintenance' (RCM), 'total productive maintenance' (TPM), 'just in time' (JIT), 'life cycle costing' (LCC), etc. have been developed over many years and are applied throughout the world today. Techniques such as 'failure mode effect and criticality analysis' (FMECA), 'fault diagnostics', 'quality circles', and others have also been introduced to the industry. However various studies (Willmott, 1990: 17) have shown that present levels of maintenance management effectiveness are still unsatisfactory. One of the most important reasons for this state of affairs is that maintenance is still viewed by many organizations as a technical activity rather than an integrated management discipline. This misconception is then reinforced by several factors such as that the maintenance department is at its most visible when an emergency malfunction occurs. As soon as the malfunction has been restored, production carries on with its activities and no one asks the question why the breakdown was not anticipated before it occurred and disrupted production. A second reason is that maintenance managers view themselves as fire fighters and not as managers. A third reason is that the maintenance department is viewed as an organizational function with unpredictable response times and erratic priorities. All of these prejudices and misconceptions are costing industry dearly. This study will indicate that much can be done to transform the maintenance function of any organization to such an extent that costs are minimized and plant availability is improved that will ultimately lead to higher profit margins.