No description available.

The first part of this thesis presents a novel design for DRAMs to provide self-refreshing cycles which vary with temperature dynamically to reduce power dissipation in a standby mode. The proposed design monitors the data loss of a memory cell which is resulted from the leakage current, and then adjusts the period of the self-refreshing cycles. The second part presents two fast half-swing CMOS circuits for NOR-NOR PLA implementation. An additional 1/2VDD voltage source and buffering transmission gates are inserted between the NOR planes of PLAs to erase the racing problem and shorten the rise delay as well as the fall delay of the output response such that the speed is enhanced.

Nitroaromatic explosives have contaminated millions of acres of soil and water across the globe since World War II with known mutagenic, carcinogenic, and ecotoxicological effects. Recently, the U.S. Army initiated a shift away from traditional explosive compounds, such as trinitrotoluene (TNT) and hexahydrotrinitrotriazine (RDX), towards new, insensitive high explosive formulations. The new formulations approved for use include “IMX-101” and “IMX-104,” which contain 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ). These mixtures are less prone to accidental detonation making storage, transport, and implementation of these formulations safer for soldiers. Furthermore, initial research indicates that these compounds are less toxic than the older analogues. Despite the apparent benefits, the new explosives have higher solubility (approximately 3-300 times) than the compounds they are replacing, and NTO and NQ are fairly recalcitrant to aerobic biodegradation. The refractory nature and high solubility of the compounds raises concerns about leaching and water contamination considering the previous scale of environmental contamination from production and use of legacy explosives, while feasible strategies for cleaning up the new chemicals from soil and water have not been developed. Therefore, there is a critical need for understanding of the mechanisms of biodegradation these compounds will undergo in the environment and in engineered systems. In addition, a number of questions remain about the photochemistry of the compounds and how they may transform in sunlit surface water. Accordingly, this thesis examines biological transformations of DNAN and NTO in vegetative, fungal, and bacterial organisms, as well as photolysis of NTO and NQ in aqueous solution and DNAN in plant leaves. I identified 34 novel biotransformation products of DNAN using stable-isotope labeled DNAN and high resolution mass spectrometry. Most identified biotransformation products were the result of a nitro-group reduction as the first metabolic step. Arabidopsis plants, a Rhizobium bacterium, and a Penicillium fungus all further metabolized DNAN to produce large, conjugated compounds, and no mineralization was observed in the systems studied. All three organisms reduced both para- and ortho-nitro groups of DNAN, with a dramatic preference for ortho reduction. I found that photodegradation of DNAN and its plant metabolites within Arabidopsis leaves could impact the phytoremediation of DNAN and other contaminants. Soil slurries acclimated to nitroaromatic wastewater degraded DNAN with and without carbon and nitrogen amendments and NTO with added carbon. Organisms capable of degrading DNAN and NTO were isolated, and NTO was transformed to urea, amino-triazolone, and hydroxyl-triazolone. Photolysis of NTO sensitized singlet oxygen formation and yielded hydroxyl-triazolone, nitrite, nitrate, and ammonium. The rate of photolysis of NTO increased over the neutral pH range, and natural organic matter quenched the photolysis of NTO. An unknown volatile product accumulated in the headspace of sealed reactors after NTO photolysis. Singlet oxygen degraded NTO and formed nitrite in stoichiometric yield. Photolysis of NQ produced nitrite and nitrate, but at high pH, the reaction occurred much faster than at neutral pH, and the mass balance of inorganic nitrogen was much lower. Further work should be done to investigate the mechanisms of and products from NTO and NQ photolysis.

NTO (3-nitro-1,2,4-triazol-5-one) is one of the new explosive compounds used in insensitive munitions (IM) and developed to replace traditional explosives, TNT and RDX. Data on NTO fate and transport is needed to determine its environmental behavior and potential for groundwater contamination. In this study, we measured how NTO in solution interacts with different types of soils and related soil properties to transport and fate behavior. We conducted a series of kinetic and equilibrium batch soil sorption experiments and saturated column transport studies under steady-state and transient conditions. NTO adsorbed very weakly to the studied soils. Adsorption coefficients (Kds) measured for NTO in a range of soils in batch experiments were less than 1 cm³ g⁻¹. There was a highly significant negative relationship between measured NTO adsorption coefficients and soil pH (P = 0.00011). In kinetic experiments, first order transformation rate estimates ranged between 0.0004 h⁻¹ and 0.0221 h⁻¹. There was a general agreement between batch and column-determined fate and transport parameters. However, transport studies showed an increase in the NTO transformation rate as a function of time, possibly indicating microbial growth.

Asynchronous design is an alternative to the more widely used synchronous design which allows for the elimination of a global clock network and associated design issues such as clock skew. Uncle is a toolflow that provides automated assistance for transforming a synchronous system specified in Verilog RTL to an asynchronous system. With assistance from Uncle an asynchronous delay-insensitive microprocessor is implemented using NULL Convention Logic (NCL) and verified to function properly. An advantage of asynchronous design is that it can be data-driven. Data-driven design allows specific blocks of logic to only be active when they are needed. Data-driven design is implemented to bypass parts of the asynchronous microprocessor. These parts included the ALU and the peripheral hardware multiplier. This resulted in a reduction of total power consumed and an increase in speed. Overall, it was concluded that asynchronous design with Uncle was a viable alternative to synchronous design.

No description available.

Cette thèse présente de nouveaux résultats liant la théorie des systèmes dits insensibles à la latence, à une sous-classe des réseaux de Pétri dénommée Marked Event Graph et son extension dite Synchronous Data Flow. Ces travaux sont intimement associés avec le problème d'ordonnancement général dénommé problème central répétitif. Nous introduisons les modèles synchrones, Marked Event Graphs, Synchronous Data Flow (SDF) et Latency Insensitive. Après, nous discutons des liens existants entre les modèles synchrones, Marked Event Graphs et Latency Insensitive ; nous montrons que le modèle Latency Insensitive est un cas particulier du modèle Marked Event Graph. Nous présentons ensuite une implémentation vérifiée formellement de Latency Insensitive. Après, nous rappelons un résultat connu : tout Marked Event Graph ayant au moins une partie fortement connexe (et s'évaluant avec une règle d'exécution As Soon As Possible (ASAP)) a un comportement ultimement répétitif : c'est à dire qu'il existe un ordonnancement statique. À partir de ce résultat, nous construisons une technique d'ordonnancement particulière dénommée Égalisation qui altère virtuellement la topologie des communications du système afin de ralentir des chemins trop rapides en rajoutant des "registres", tout en conservant les performances en terme de débit du système originel. Enfin, nous introduisons une notion de contrôle limité au modèle Latency Insensitive, avec des noeuds appelés select et merge dont les conditions sont connueset indépendantes des flots de données, plus exactement les conditions d'aiguillage des données sont dirigées par des mots binaires ultimement périodiques (comme dans le cadre de l'ordonnancement statique). Nous effectuons ensuite une abstraction sur le modèle SDF afin de déterminer si le modèle accepte un ordonnancement où la taille de toute place est bornée. Nous pouvons vérifier ensuite la vivacité du système grâce à une simulation, si le modèle originel disposait d'au moins d'une partie fortement connexe. Finalement, nous concluons et discutons des possibilités de travaux futurs.

New explosive compounds that are less sensitive to shock and high temperatures are being tested on military ranges as replacements for 2, 4, 6-trinitrotoluene (TNT) and hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX). One of the two compounds being tested is 2, 4-dinitroanisole (DNAN), which has good detonation characteristics and is one of the main ingredients in a suite of explosive formulations being tested. Data on the fate and transport of DNAN is needed to determine its potential to reach groundwater and be transported off base, a result which could create future contamination problems on military training ranges and trigger regulatory action. In this study, I measured how DNAN in solution interacts with different types of soils from across the United States. I conducted kinetic and equilibrium batch soil adsorption experiments, saturated column experiments with DNAN and dissolution and transport studies of insensitive munitions (IMX-101, IMX -104), which include DNAN, 3-nitro-1,2,4-triazol-5-one (NTO), nitroguanidine (NQ) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), under steady state and transient conditions. In the rate studies, change in DNAN concentration with time was evaluated using the first order kinetic equation. Solution mass-loss rate coefficients ranged between 0.0002 h-1 and 0.0068 h-1. DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3 L kg-1, and Freundlich coefficients between 1.3 and 34 mg1-n Ln kg-1. Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil. In saturated miscible-displacement experiments, it was shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-amino-4-nitroanisole (2-ANAN) and 4-amino-2-nitroanisole (4-ANAN). Dissolution miscible-displacement experiments demonstrated that insensitive munition compounds dissolved in order of aqueous solubility as indicated by earlier lab and outdoor dissolution studies. The sorption of NTO and NQ was low, while RDX, HMX, and DNAN all adsorbed to the soils. DNAN transformed in soils with formation of amino-reduction products, 2- ANAN and 4-ANAN. Adsorption parameters determined by HYDRUS-1D generally agreed with batch and column study adsorption coefficients for pure NTO and DNAN. The magnitudes of retardation and transformation observed in these studies result in significant attenuation potential for DNAN in soils, which would reduce risk of groundwater contamination.

Resource management is important for network design and deployment. Resource management and allocation have been studied under a wide variety of scenarios --- routing in wired networks, scheduling in cellular networks, multiplexing, switching, and channel access in opportunistic networks are but a few examples. In this dissertation, we revisit resource management in the context of routing and scheduling in multihop wireless networks and pricing in single resource systems. The first issue addressed is of delays in multihop wireless networks. The resource under contention is capacity which is allocated by a joint routing and scheduling algorithm. Delay in wireless networks is a key issue gaining interest with the growth of interactive applications and proliferation of wireless networks. We start with an investigation of the back-pressure algorithm (BPA), an algorithm that activates the schedule with the largest sum of link weights in a timeslot. Though the BPA is throughput-optimal, it has poor end-to-end delays. Our investigation identifies poor routing decisions at low loads as one cause for it. We improve the delay performance of max-weight algorithms by proposing a general framework for routing and scheduling algorithms that allow directing packets towards the sink node dynamically. For a stationary environment, we explicitly formulate delay minimization as a static problem while maintaining stability. We see similar improved delay performance with the advantage of reduced per time-slot complexity. Next, the issue of pricing for flow based models is studied. The increasing popularity of cloud computing and the ease of commerce over the Internet is making pricing a key issue requiring greater attention. Although pricing has been extensively studied in the context of maximizing revenue and fairness, we take a different perspective and investigate pricing with predictability. Prior work has studied resource allocations that link insensitivity and predictability. In this dissertation, we present a detailed analysis of pricing under insensitive allocations. We study three common pricing models --- fixed rate pricing, Vickrey-Clarke-Groves (VCG) auctions, and congestion-based pricing, and provide the expected operator revenue and user payments under them. A pre-payment scheme is also proposed where users pay on arrival a fee for their estimated service costs. Such a mechanism is shown to have lower variability in payments under fixed rate pricing and VCG auctions while generating the same long-term revenue as in a post-payment scheme, where users pay the exact charge accrued during their sojourn. Our formulation and techniques further the understanding of pricing mechanisms and decision-making for the operator.

Resource management is important for network design and deployment. Resource management and allocation have been studied under a wide variety of scenarios --- routing in wired networks, scheduling in cellular networks, multiplexing, switching, and channel access in opportunistic networks are but a few examples. In this dissertation, we revisit resource management in the context of routing and scheduling in multihop wireless networks and pricing in single resource systems. The first issue addressed is of delays in multihop wireless networks. The resource under contention is capacity which is allocated by a joint routing and scheduling algorithm. Delay in wireless networks is a key issue gaining interest with the growth of interactive applications and proliferation of wireless networks. We start with an investigation of the back-pressure algorithm (BPA), an algorithm that activates the schedule with the largest sum of link weights in a timeslot. Though the BPA is throughput-optimal, it has poor end-to-end delays. Our investigation identifies poor routing decisions at low loads as one cause for it. We improve the delay performance of max-weight algorithms by proposing a general framework for routing and scheduling algorithms that allow directing packets towards the sink node dynamically. For a stationary environment, we explicitly formulate delay minimization as a static problem while maintaining stability. We see similar improved delay performance with the advantage of reduced per time-slot complexity. Next, the issue of pricing for flow based models is studied. The increasing popularity of cloud computing and the ease of commerce over the Internet is making pricing a key issue requiring greater attention. Although pricing has been extensively studied in the context of maximizing revenue and fairness, we take a different perspective and investigate pricing with predictability. Prior work has studied resource allocations that link insensitivity and predictability. In this dissertation, we present a detailed analysis of pricing under insensitive allocations. We study three common pricing models --- fixed rate pricing, Vickrey-Clarke-Groves (VCG) auctions, and congestion-based pricing, and provide the expected operator revenue and user payments under them. A pre-payment scheme is also proposed where users pay on arrival a fee for their estimated service costs. Such a mechanism is shown to have lower variability in payments under fixed rate pricing and VCG auctions while generating the same long-term revenue as in a post-payment scheme, where users pay the exact charge accrued during their sojourn. Our formulation and techniques further the understanding of pricing mechanisms and decision-making for the operator.