Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Normal hearing is typically defined by threshold audibility, or the loudness of sounds that an individual is able to hear. This convention exists despite the fact that everyday communication relies on extracting and interpreting features of supra-threshold sound. Many normal-hearing listeners struggle to perform certain supra-threshold auditory tasks, and debate persists as to whether such difficulties originate from deficits in cognitive processing or in peripheral, sensory encoding. In this work, we show that there are large individual differences among normal-hearing adults (18 to 55 years), who were asked to report a stream of digits located directly ahead in a simulated rectangular room. Simultaneous, competing masker digit streams were simulated at locations 15° left and right of center, and the level of reverberation was adjusted to vary task difficulty. Performance was best in the anechoic condition and worst in the high-reverberation condition, but listeners nearly always reported a digit from one of the three competing streams, showing that reverberation did not render the digits unintelligible. Most importantly, inter-subject differences were extremely large. These differences were not significantly correlated with age, memory span, or hearing status. They were, however, correlated with behavioral differences in the ability to detect small frequency modulations in pure tones and with the strength of the frequency following response (FFR), a physiological measure of spectro-temporal detail encoding in supra-threshold sounds early in the auditory pathway. The decomposition of the FFR into envelope and carrier components shows that envelope frequency following is the preferred cue for completing the spatial attention task, but it degrades with early aging. As a result, older listeners depend more on carrier phase locking cues than younger people. These results suggest that differences in peripheral encoding help explain individual differences in the ability to communicate in challenging settings, but that aging also has a separate, dissociable effect on early encoding in the auditory system. Tests like these may help tease apart contributions of peripheral and central deficits to communication impairments, ultimately leading to new approaches for helping listeners cope with complex listening environments. / 2999-01-01

Since petroleum is a kind of exhaustive resource, it can not be regenerated after being consumed. And petroleum is distributed extremely uneven in the world, more than half of petroleum is distributed in the Middle East area. In the recent years, the oil price was so fluctuating and broke the record again and again. However, the productivity of petroleum in Taiwan is very low and we are a price taker. So it turns to be important that how the oil price affects the economy. According to Economics, high oil price often causes the staginflation. In the purpose of this study we examine the long run relationship between oil price and personal income in Taiwan by cointegration theory. And we find that there indeed exists a negative longrun relationship. In addition, we consider a nonlinear model, Threshold Vector Error Correction Model, to test a threhold effect in the long run relationship between variables. Finally we have a result that there is a threshold cointegrating relationship between the oil price and personal income in Taiwan.

Threshold logic gates allow for complex multi-input functions to be implemented using a single gate reducing the power and area of the circuit. Clocked based threshold gates have the additional advantage of its capability of being nanopipelined to increase network throughput. To produce a threshold network the proposed algorithm accepts a traditional algebraic boolean network as an input and resynthesizes it into a nanopipelined threshold logic network. The algorithm is the first to our knowledge that synthesizes in a manner to not only minimize the number of clusters produced from synthesizing the algebraic boolean network but also to minimize associated buffer insertion overhead in producing a clocked threshold gate network.

[pt] A primeira parte deste trabalho consiste num estudo das desigualdades lineares que aparecem na síntese de funções lógicas por single-threshold. São desenvolvidas condições necessárias e suficientes para existência de solução, e também estabelecidas condições para a redução das desigualdades. Na segunda parte é proposto um método para calcular uma solução ótima para o sistema, sob certas condições de projeto. Finalmentesão apresentados métodos para realiza, com multithreshold devices, funções lógicas não realizáveis por single-threshold devices. / [en] The first part of this thesis is a theoretical study of sets of inequalities that appear in the synthesis of logical sufficient conditions are developd for existence of solution of the inequalities. In the second part, a numerical method for calculating proposed. Following this development, logical functions that cannot be realized by a single-threshold device are studied. Using the conditions developed before for single- threshold, methods are presented for realization of these functions by multithreshold devices.

Thesis (Ph.D.)--University of Nevada, Reno, 2006. / "August, 2006." Includes bibliographical references (leaves 103-110). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Power consumption of VLSI (Very Large Scale Integrated) circuits has been growing at an alarmingly rapid rate. This increase in power consumption, coupled with the increasing demand for portable/hand-held electronics, has made power consumption a dominant concern in the design of VLSI circuits today. Traditionally dynamic (switching) power has dominated the total power consumption of VLSI circuits. However, due to process scaling trends, leakage power has now become a major component of the total power consumption in VLSI circuits. This dissertation explores techniques to reduce leakage, as well as techniques to exploit leakage currents through the use of sub-threshold circuits. This dissertation consists of two studies. In the first study, techniques to reduce leakage are presented. These include a low leakage ASIC design methodology that uses high VT sleep transistors selectively, a methodology that combines input vector control and circuit modification, and a scheme to find the optimum reverse body bias voltage to minimize leakage. As the minimum feature size of VLSI fabrication processes continues to shrink with each successive process generation (along with the value of supply voltage and therefore the threshold voltage of the devices), leakage currents increase exponentially. Leakage currents are hence seen as a necessary evil in traditional VLSI design methodologies. We present an approach to turn this problem into an opportunity. In the second study in this dissertation, we attempt to exploit leakage currents to perform computation. We use sub-threshold digital circuits and come up with ways to get around some of the pitfalls associated with sub-threshold circuit design. These include a technique that uses body biasing adaptively to compensate for Process, Voltage and Temperature (PVT) variations, a design approach that uses asynchronous micro-pipelined Network of Programmable Logic Arrays (NPLAs) to help improve the throughput of sub-threshold designs, and a method to find the optimum supply voltage that minimizes energy consumption in a circuit.

This paper uses a two-regime vector error-correction with a single cointegrating vector and a threshold in the error-correction term introduced by Hansen and Seo(2002). We propose a SupLM test for the presence of a threshold. We derive the asymptotic distribution and show how to simulate asymptotic critical region. Applying our methods to the 90-days and 180-days Commercial Paper rate, we find that there are an apparent threshold effect and inconsistent behaviors in the long-run equilibrium process.

Taiwan is usually considered as a small open economy. Trade and exchange rate policies in Taiwan have substantially changed since the mid-1980s. Not only has trade been liberalized, but exchange rates of the New Taiwan Dollar(NTD) were also allowed to fluctuate. This paper applies the Threshold Regression Model that puted forward of Cancer and Hansen (2004) and combines the expectation-augmented Phillips curve with a threshold for the pass-through. The paper examines whether the short-run magnitude of the pass-through is affected by the business cycle, direction and magnitude of the exchange rate change. For that purpose, two variables are tested as thresholds: (1)output gap, (2)exchange rate change. The results indicate that the short-run pass-through is higher when the economy is booming, as well as the exchange rate depreciates above some threshold. And they have important implications for monetary policy and are possibly related to pricing-to-market behavior and menu costs of price a djustment.

Two different topics associated with their respective applications are proposed in this thesis. The first topic is the implementation of a 6-T SRAM cell using dual threshold voltage transistors and low power quenchers. We proposed a SRAM cell with dual threshold voltage transistors. The advantages of such a design is to reduce the access time and maintain data retention at the same time. Besides, the unwanted oscillation of the output data lines caused by large currents is reduced by adding two back-to-back quenchers. The second topic is focused on the implementation of a programmable PLL-based frequency multiplier. Using the method of a phase-locked loop and a programmable divisor to implement a frequency multiplier. ¢Ï synchronous clock signal can be generated by the proposed design. It can also be used in wireless communication systems, e.g. local oscillators.

Given the role electricity and natural gas sectors play in the North American economy, an understanding of how markets for these commodities interact is important. This dissertation independently characterizes the price dynamics of major electricity and natural gas spot markets in North America by combining directed acyclic graphs with time series analyses. Furthermore, the dissertation explores a generalization of price difference bands associated with the law of one price. Interdependencies among 11 major electricity spot markets are examined in Chapter II using a vector autoregression model. Results suggest that the relationships between the markets vary by time. Western markets are separated from the eastern markets and the Electricity Reliability Council of Texas. At longer time horizons these separations disappear. Palo Verde is the important spot market in the west for price discovery. Southwest Power Pool is the dominant market in Eastern Interconnected System for price discovery. Interdependencies among eight major natural gas spot markets are investigated using a vector error correction model and the Greedy Equivalence Search Algorithm in Chapter III. Findings suggest that the eight price series are tied together through sixlong-run cointegration relationships, supporting the argument that the natural gas market has developed into a single integrated market in North America since deregulation. Results indicate that price discovery tends to occur in the excess consuming regions and move to the excess producing regions. Across North America, the U.S. Midwest region, represented by the Chicago spot market, is the most important for price discovery. The Ellisburg-Leidy Hub in Pennsylvania and Malin Hub in Oregon are important for eastern and western markets. In Chapter IV, a threshold vector error correction model is applied to the natural gas markets to examine nonlinearities in adjustments to the law of one price. Results show that there are nonlinear adjustments to the law of one price in seven pair-wise markets. Four alternative cases for the law of one price are presented as a theoretical background. A methodology is developed for finding a threshold cointegration model that accounts for seasonality in the threshold levels. Results indicate that dynamic threshold effects vary depending on geographical location and whether the markets are excess producing or excess consuming markets.