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Articles 1681 - 1710 of 2429

Full-Text Articles in Physical Sciences and Mathematics

The Impact Of Sprawl On Transportation Energy Copnsumption And Transportation Carbon Footprint In Large U.S. Cities, Leila Ahmadi Jan 2012

The Impact Of Sprawl On Transportation Energy Copnsumption And Transportation Carbon Footprint In Large U.S. Cities, Leila Ahmadi

Earth & Environmental Sciences Dissertations - Archive

Today, climate change and energy shortage are major concerns among scientists, politicians, and economists. For decades in the U.S., emphasis has been placed on improving energy efficiency through technological advances. However, most of these technologies are in the initial phases of development, while energy consumption continues to increase at a rapid pace. In order to solve this dilemma, there is a need to develop a faster and more effective approach for controlling the rates of energy consumption and demand. Transportation consumes more energy than other energy-dependent activities, such as those in the industrial, residential, and commercial sectors of the economy. …

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Biomarkers: Review And Application To The Eagle Ford Shale Formation, Ugochukwu Ononogbu Jan 2012

Biomarkers: Review And Application To The Eagle Ford Shale Formation, Ugochukwu Ononogbu

Earth & Environmental Sciences Theses - Archive

Biomarkers have become an integral part of oil exploration. Gas Chromatography (-Mass Spectrometry) was performed to an oil sample to acquire biomarkers from the sample.The presence, lack of, or abundance of a given compound (or biomarker) in the geochemicalresults of an oil sample depict(s) a property or properties of the source rock and the oil. Forexample, the abundance of pristane and lack of phytane in an oil sample are characteristic ofshale source rock, and the results from the Eagle Ford shale formation show a high pristane tophytane ratio.The Eagle Ford shale formation is cretaceous in age; the presence and absence …

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A Late Holocene Meander-Braid Transition Of The Lower Missouri River Valley, Michele Viola Kashouh Jan 2012

A Late Holocene Meander-Braid Transition Of The Lower Missouri River Valley, Michele Viola Kashouh

Earth & Environmental Sciences Theses - Archive

Historically, the Lower Missouri River is known for being a temperate river that constantly and quickly reworks its floodplain with a braided network of channels; however, the river only recently became braided. Ox-bow lakes and landscape features resembling highly sinuous meandering loops mark the floodplain of the lower Missouri River Valley as scars of what was once a fully meandering Missouri River. The unanswered question then is, when did the lower Missouri River system change from meandering to braided? To answer this question we compared a series of newly created allostratigraphic maps of the lower Missouri River valley floor to …

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Microfaunal Assemblages Of The Placid Shale (Missourian, Upper Pennsylvanian), Brazos River Valley, North-Central Texas, Brittany E. Meagher Jan 2012

Microfaunal Assemblages Of The Placid Shale (Missourian, Upper Pennsylvanian), Brazos River Valley, North-Central Texas, Brittany E. Meagher

Earth & Environmental Sciences Theses - Archive

The Pennsylvanian and lowermost part of the Permian strata in North-Central Texas is assigned to the Strawn, Canyon, and Cisco Groups. The Canyon Group is approximately equivalent to the middle-upper part of the Missourian (Upper Pennsylvanian) and crops out in the Brazos River valley in a generally northeast-southwest strip across Palo Pinto and Jack counties. The Canyon Group is subdivided into seven formations that contain several cycles of well-known clastic and carbonate units. The Placid Shale, one of the clastic units within the Canyon Group, consists of two cycles of gray, brown, olive sandstone/siltstone/mudstone with few thin limestone beds. It …

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High Resolution Geochemistry Of The Cretaceous Eagle Ford Shale, Bee County, Texas, Lisa Michelle Moran Jan 2012

High Resolution Geochemistry Of The Cretaceous Eagle Ford Shale, Bee County, Texas, Lisa Michelle Moran

Earth & Environmental Sciences Theses - Archive

The Eagle Ford Formation of Bee County, Texas is a sporadically laminated carbonaceous dark mudrock. The depositional area of the Eagle Ford Formation stretches across the state of Texas in a northeast-southwest trend. Early studies of the Eagle Ford found the deposits to be rich in organic material but could not fully describe the formation due to the lack of outcrop exposure. Recent studies of the Eagle Ford Formation have begun to explore the sub-surface nature of the formation. Geochemical analyses of the J.A. Leppard #1 core from the southwestern portion of the formation was conducted to further constrain the …

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Growth Rates Of The Harmful Alga Prymnesium Parvum: An Attempt To Identify The Salinity Threshold For Algal Blooms, James William Cody Black Jan 2012

Growth Rates Of The Harmful Alga Prymnesium Parvum: An Attempt To Identify The Salinity Threshold For Algal Blooms, James William Cody Black

Earth & Environmental Sciences Theses - Archive

Harmful algal blooms due to Prymnesium parvum have occurred in Texas for nearly three decades in waters of moderate salinity. More recently, blooms have occurred in locations such as West Virginia, in waters of very low salinity where pollution discharges are suspected to have increased salinity to levels that support growth of P. parvum. These observations raise the question, what is the lowest salinity at which this species of algae can cause toxic fish kills? Previous research based on field observations has suggested a salinity threshold of about 1.5 PSU for occurrence of blooms in Texas reservoirs in winter. Other …

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Chemostratigraphy, Paleoceanography, And Sequence Stratigraphy Of The Pennsylvanian-Permian Section In The Midland Basin Of West Texas With Focus On The Wolfcamp Formation, Milton Cortez Jan 2012

Chemostratigraphy, Paleoceanography, And Sequence Stratigraphy Of The Pennsylvanian-Permian Section In The Midland Basin Of West Texas With Focus On The Wolfcamp Formation, Milton Cortez

Earth & Environmental Sciences Theses - Archive

The late Pennsylvanian to early Permian rocks (Wolfcampian and Leonardian) of the Midland Basin represent a single lithologic unit composed primarily of calcareous mudrocks, siliceous mudrocks, muddy carbonate-clast conglomerates, and skeletal packstones/grainstones at the approximate depositional center located in Reagan County, Texas. Pure versions of these lithologic end-members are discretely distributed among a multitude of transitional lithofacies. The Midland Basin evolved in the foreland of the Ouachita Fold-belt from Mississippian to early Permian time along-side several sub-basins of the Permian Basin. These basins were formed by disseverance and uplift associated with the continental collision of Laurasia and Gondwana to form …

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Chemostratigraphy And Paleoenvironmental Significance Of The Pennsylvanian Smithwick Formation, Northern Llano Uplift Region, Texas, Rene Bernabe Ovalle-Rauch Jan 2012

Chemostratigraphy And Paleoenvironmental Significance Of The Pennsylvanian Smithwick Formation, Northern Llano Uplift Region, Texas, Rene Bernabe Ovalle-Rauch

Earth & Environmental Sciences Theses - Archive

The Early Pennsylvanian (Bashkirian-Moscovian) Smithwick Formation of Central Texas has been previously described as a marine transgressive, fairly homogeneous and fine-grained dark shale sequence with varying local depositional lithofacies. The deposition of the Smithwick shale through the southern margin of the Fort Worth Basin (FWB) has shown large variability in thickness and deposition style. Lithological heterogeneity of the bounding units throughout the basin is inferred to be the result of a combination of depositional, tectonic and eustatic variations. Regional structural instability from Late Mississippian to Early Pennsylvanian is linked to the reactivation of the Ouachita geosyncline and thrust front, causing …

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Resolutions And Tor Algebra Structures For Trivariate Monomial Ideals, Jared Lafayette Painter Jan 2012

Resolutions And Tor Algebra Structures For Trivariate Monomial Ideals, Jared Lafayette Painter

Mathematics Dissertations - Archive

In this manuscript we explore properties of minimal free resolutions and their relationship to the Tor-algebra structure for trivariate monomial ideals. We begin with an in-depth analysis of minimal free resolutions of S = R / I, where R = k[x; y; z] is a polynomial ring over a field k, and I is a monomial ideal that is primary to the homogeneous maximal ideal m of R. We will de ne a special form of the minimal free resolution of S, and then determine when we get nonzero elements from I as entries in the matrices of the resolution. …

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High Order Dns For Late Flow Transition, Ping Lu Jan 2012

High Order Dns For Late Flow Transition, Ping Lu

Mathematics Dissertations - Archive

In this report, a new high order scheme for boundary points is introduced when calculating the derivative of smooth functions by Compact Scheme. The primitive function reconstruction method of ENO schemes is applied to obtain the conservative form of the Compact Scheme. Meanwhile, modified compact scheme is developed by using an effective shock detector to block upwinding compact scheme to cross the shock, a control function, and an adaptive scheme which uses some WENO flux near the shock. The new scheme makes the original upwinding compact scheme able to capture the shock sharper than WENO and, more important, keep high …

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From Discrete To Continuous Models Of Cell Movement: An Application To Medical Implants, Alicia Prieto Langarica Jan 2012

From Discrete To Continuous Models Of Cell Movement: An Application To Medical Implants, Alicia Prieto Langarica

Mathematics Dissertations - Archive

Mathematical modeling of cell movement is needed to aid in the deeper understanding of vital processes such as embryogenesis, angiogenesis, tumor metastasis, and immune reactions to foreign bodies. In this work, cell movement and growth in response to external stimulus and the interactions between cells and the stimulus are considered. In order to model the random nature of the movement, a discrete model is created to simulate cells moving in the presence of a growing and moving stimulus distribution. The model also includes the depletion of the stimulus under the presence of cells. The discrete model is then upscaled, based …

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A Study On The Two Component Periodic Shallow Water Systems, Caixia Chen Jan 2012

A Study On The Two Component Periodic Shallow Water Systems, Caixia Chen

Mathematics Dissertations - Archive

In this dissertation we study the generalized periodic two-component Camassa-Holm system and the generalized periodic two-component Dullin-Gottwald-Holm system, which can be derived from the Euler equation with nonzero constant vorticity in shallow water waves moving over a linear shear flow. The precise blow-up scenarios of strong solutions and several results of blow-up solutions with certain initial profiles are described in detail. The exact blow-up rates are also determined. Finally, the sufficient conditions for global solutions are established.

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A Game Theoretic Framework For Communication Decisions In Multi Agent Systems, Tummalapalli Sudhamsh Reddy Jan 2012

A Game Theoretic Framework For Communication Decisions In Multi Agent Systems, Tummalapalli Sudhamsh Reddy

Computer Science and Engineering Dissertations - Archive

Communication is the process of transferring information between multiple entities. We study the communication process between different entities that are modeled as multiple agents. To study the interactions between these entities we use Game theory, which is a mathematical tool that is used to model the interactions and decision process of these multiple players/agents. In the presence of multiple players their interactions are generally modelled as a stochastic game.Here we assume that the communication medium, protocols and language are already present in this multiagent system. We address the question of information selection in the communication process.In this thesis, we develop …

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Nonlinear Dynamics And Stochasticity Of Core Genetic Regulation, Hongguang Xi Jan 2012

Nonlinear Dynamics And Stochasticity Of Core Genetic Regulation, Hongguang Xi

Mathematics Theses - Archive

Bacillus subtilis is one of the very well-studied organisms in biology. Recent results show that an alternative competence regulation circuit for this bacterium, differing only in the order of the composite negative feedback loop onto the master competence regulator gene comK, despite presenting equivalent functionality, exhibits physiologically important differences.It is not clear why Nature only selects a specific gene regulation circuit other than a plethora of equivalent others. Here, we hope, from the point of view of reverse engineering, to discover the fundamental reasons for natural selection of a particular circuit structure over another. Based on the wild-type Bacillus subtilis …

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A Study Of The Viscous Interaction Between The Solar Wind And Earth's Magnetosphere Using An Mhd Simulation, Robert Jeffrey Bruntz Jan 2012

A Study Of The Viscous Interaction Between The Solar Wind And Earth's Magnetosphere Using An Mhd Simulation, Robert Jeffrey Bruntz

Physics Dissertations - Archive

The solar wind interacts with Earth's magnetosphere largely through magnetic reconnection and a “viscous-like” interaction that is not fully understood. The ionospheric cross-polar cap potential (ΦPC) component due to reconnection (ΦR) is typically much larger than the viscous component (ΦV) and very dynamic, making detailed studies of the viscous potential difficult. We used the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamic (MHD) simulation to study the viscous potential by running LFM for a variety of solar wind density and velocity values and ionospheric Pedersen conductance (ΣP) values, but no solar wind magnetic field, so that ΦPC was entirely due to the viscous interaction. We …

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Two-Photon Optogenetic Stimulation Of Cells, Kamal Raj Dhakal Jan 2012

Two-Photon Optogenetic Stimulation Of Cells, Kamal Raj Dhakal

Physics Theses - Archive

The controlled stimulation of cells, especially neurons, is of significant interest both for basic understanding of neuronal circuitry as well as clinical interventions. Existing electrode-based methods of stimulation are invasive and non-specific to highly localized regions or specific cell types. Recently, optical stimulation of targeted neurons expressing light-sensitive proteins (opsins) using visible light has emerged as a powerful technique in neuroscience. However, the use of these optogenetic tools as a minimally invasive technique for in-vivo applications is limited to the study/intervention of superficial regions of the brain since, due to absorption and scattering, a significant amount of the visible light …

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Implementation Of A Middleware Architecture For Collaboration Among Mobile Devices In Opportunistic Networks., Samaya Madhavan Jan 2012

Implementation Of A Middleware Architecture For Collaboration Among Mobile Devices In Opportunistic Networks., Samaya Madhavan

Computer Science and Engineering Theses - Archive

Opportunistic networks provide a viable platform for mobile communications due to the ubiquity of smart phones. These networks are characterized by lack of end to-end reliable connections. In such networks, establishing collaboration among nodes is a challenge. In this thesis, a middleware architecture for opportunistic communication and collaboration has been designed, developed, and implemented. The middleware architecture supports a protocol for efficiently exchanging information between mobile nodes during an opportunistic contact. Message formats for differentiating the various kinds of messages that will be transferred across the network are defined to maintain consistency and reduce redundancy. The architecture consists of several …

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Subrosa 2 : An Experimental Evaluation Of Timing Analysis Attacks And Defenses In Anonymity Systems, Payap Sirinam Jan 2012

Subrosa 2 : An Experimental Evaluation Of Timing Analysis Attacks And Defenses In Anonymity Systems, Payap Sirinam

Computer Science and Engineering Theses - Archive

A circuit-based low-latency anonymous communication service such as Tor helps Internet users hide their IP addresses and thereby conceal their identities when communicating online. However, this kind of service is vulnerable to timing analysis attacks that can discern the relationship between incoming and outgoing messsages in order to find correlations between them. The attacker can use this information to reveal the idenity of the internet users without knowing the IP addresses concealed in the anonymous communication services.Dependent link padding (DLP) is a scheme propsed to enable anonymity systems to resist these attacks. However, DLP adds high overhead from dummy packets …

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An Extensible Self-Adapting Dissemination Framework For High-Speed Continuous Xml Streaming Data, Anthony E. Okorodudu Jan 2012

An Extensible Self-Adapting Dissemination Framework For High-Speed Continuous Xml Streaming Data, Anthony E. Okorodudu

Computer Science and Engineering Dissertations - Archive

The efficient dissemination of data has become increasingly important with recent advances in technology that provide us immediate access to information at our fingertips. The insatiable demand for data has increased significantly with the popularity and widespread use of smart phones and tablets throughout the world. This thesis is focused on efficient push-based means of disseminating data to a large number of interested clients using a network of co-operating machines, called brokers.There have been extensive studies in optimizing both XML filtering and XPath-based subscription management in publish/subscribe systems with the aim of disseminating data in a timely fashion. Much less …

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Energy-Efficient Protocols And Systems For Wireless Sensor Networks And Smart Environments, Giacomo Ghidini Jan 2012

Energy-Efficient Protocols And Systems For Wireless Sensor Networks And Smart Environments, Giacomo Ghidini

Computer Science and Engineering Dissertations - Archive

In a wireless sensor network, small computing devices, called sensors, sense the surrounding environment and relay the sensed data to a base station over a multi-hop wireless network, eventually processing them en-route. Wireless sensor networks and other devices, such as smartphones, smart meters, and smart appliances, cooperate in smart environments to obtain information about the environment, and then use this information to improve the experience of the users. Since most of these systems rely on battery power, there is a need for energy-efficient solutions for their operation. The objective of this dissertation is to design algorithms and protocols to improve …

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System For Interpretation Of Reviewer Feedback On Social Web, Shrikant Desai Jan 2012

System For Interpretation Of Reviewer Feedback On Social Web, Shrikant Desai

Computer Science and Engineering Theses - Archive

The increasing popularity of social media web sites such as Amazon, Yelp and others has influenced our online decision making. Before making selection decisions on movies and restaurants, we investigate its reviewer feedback. Social media web sites provide reviewer feedback in the form of ratings, tags, and user reviews. However, overwhelming feedback details will leave the user in a quandary as to decide whether the item is desirable or not. Potential buyers either make a snap judgment based on the aggregate ratings/tags or spend a lot of time in reading reviews.In this thesis, we build a system that can analyse …

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Learning Partially Observable Markov Decision Processes Using Abstract Actions, Hamed Janzadeh Jan 2012

Learning Partially Observable Markov Decision Processes Using Abstract Actions, Hamed Janzadeh

Computer Science and Engineering Theses - Archive

Transfer learning and Abstraction are among the new and most interesting research topics in AI and address the use of learned knowledge to improve learning performance in subsequent tasks. While there has been significant recent work on this topic in fully observable domain, it has been less studied for Partially Observable MDPs. This thesis addresses the problem of transferring skills from the previous experiences in POMDP models using high-level actions (Options) in two different kind of algorithms: value iteration and expectation maximization. To do this, this thesis first proves that the optimal value function remains piecewise-linear and convex when policies …

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Selective Grouping Algorithm For Low Latency Anonymous Systems, Vishal Gupta Jan 2012

Selective Grouping Algorithm For Low Latency Anonymous Systems, Vishal Gupta

Computer Science and Engineering Theses - Archive

Low latency anonymous communications are prone to timing analysis attacks. It is a technique by which the adversary can de-anonymize the user by correlating packet timing patterns. A recent proposal to stop these attacks is called Dependent Link padding. However, it creates high dummy packets overhead in the network. In this work we propose selective grouping, a padding scheme that protects users in an anonymity system from those attacks with minimal overhead. The aim is to decrease overhead by dividing users in different groups while maintaining good anonymity. The key idea of our approach is to group clients with similar …

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Similarity Measures And Indexing Methods For Time Series And Multiclass Recognition, Alexandra Stefan Jan 2012

Similarity Measures And Indexing Methods For Time Series And Multiclass Recognition, Alexandra Stefan

Computer Science and Engineering Dissertations - Archive

This thesis investigates the problem of similarity search in multimedia databases. A key application domain of the proposed work is pattern classification, with emphasis on classification of gestures, handshapes, faces, and time series. A secondary application of the proposed work is efficient similarity search in large biological databases of protein sequences.More specifically, the thesis makes contributions both by defining novel similarity measures, that are used to identify the best database matches, and by proposing methods to improve efficiency. On the topic of similarity measures, the thesis contributes a method for measuring similarity in a database of videos from American Sign …

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Shaping And Maintenance Of Low-Latency Anonymity Systems, Harsha Doreswamy Jan 2012

Shaping And Maintenance Of Low-Latency Anonymity Systems, Harsha Doreswamy

Computer Science and Engineering Theses - Archive

Surveillance of users on the Internet is growing. This makes it increasingly important to protect users' identity when they communicate online, especially for users like journalists, whistleblowers, and military officials. Anonymity systems can conceal users' identities and provide anonymity for their online activities. Low-latency anonymity systems like Tor are designed to provide support for applications like Web browsing, video streaming, and online chat. To make the commutation between source and destination unlinkable, Tor routes all the traffic through three Tor relays, which are spread across the globe. These three relays are usually chosen without considering the delay to get from …

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Choices And Consequences: A Game-Based Risky Behavior Prevention Program, Amanda Michelle Vines Jan 2012

Choices And Consequences: A Game-Based Risky Behavior Prevention Program, Amanda Michelle Vines

Computer Science and Engineering Theses - Archive

Serious games have been defined as a mental contest played with a computer in accordance to specific rules that use entertainment to further government or corporate training, education, health, public policy and strategic communication objectives. There have been various studies done to gauge the effectiveness of serious games to teach and engage. In collaboration with professors in social work and computer science, we have designed a multiplayer, social, serious game called Choices and Consequences (C&C) in an effort to better reach the audience of pre-teens and teens in order to reduce the risk taking behaviors of youth today. The game …

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Routing And Channel Assignment Schemes For Interference Avoidance In Wireless Mesh Networks, Fawaz Saleem Bokhari Jan 2012

Routing And Channel Assignment Schemes For Interference Avoidance In Wireless Mesh Networks, Fawaz Saleem Bokhari

Computer Science and Engineering Dissertations - Archive

This dissertation presents efficient routing and channel assignment schemes for interference avoidance in wireless mesh networks (WMNs). The most significant contributions of this dissertation are the development and design of two routing algorithms that help in improving network throughput by selecting less interference paths both for single and multiple radio WMNs and the design of an intelligent channel assignment scheme which increases the overall network capacity by assigning partially overlapped channels having less interference among neighboring ones for multi radio multi channel wireless mesh networks (MRMC-WMNs). For single radio single channel WMNs, we propose AMIRA (Ant Mesh routing for InteRference …

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Improving Quality Of Service In Xml Data Stream Processing Using Load Shedding, Ranjan Dash Jan 2012

Improving Quality Of Service In Xml Data Stream Processing Using Load Shedding, Ranjan Dash

Computer Science and Engineering Dissertations - Archive

In recent years, we have witnessed the emergence of new types of systems that deal with large volumes of streaming data. Examples include nancial data analy- sis on feeds of stock tickers, sensor-based environmental monitoring, network tra c monitoring and click stream analysis to push customized advertisements or intrusion detection. Traditional database management systems (DBMS), which are very good at managing large volumes of stored data, fall short of serving this new class of appli- cations, which require low-latency processing on live data from push-based sources. Data Stream Management Systems (DSMS) are fast emerging to address this new type of …

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Reducing The Complexity Of Reinforcement Learning In Pomdps By Decomposition Into Decision And Perceptual Processes, Rasool Fakoor Jan 2012

Reducing The Complexity Of Reinforcement Learning In Pomdps By Decomposition Into Decision And Perceptual Processes, Rasool Fakoor

Computer Science and Engineering Theses - Archive

Markov Decision Processes (MDPs) and Partially Observable Markov Decision Processes (POMDPs) are very powerful and general frameworks to model decision and decision learning tasks in a wide range of problem domains. As a result, they are widely used in complex and real-world situations such as robot control tasks. However, the modeling power and generality of the frameworks comes at a cost in that the complexity of the underlying models and corresponding algorithms grows dramatically as the complexity of the task domain increases. To address this , this work presents an integrated and adaptive approach that attempts to reduce the complexity …

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Measurements Of A Latency-Biased Expander Topology In The Tor Anonymity System, Subhasish Dutta Chowdhuri Jan 2012

Measurements Of A Latency-Biased Expander Topology In The Tor Anonymity System, Subhasish Dutta Chowdhuri

Computer Science and Engineering Theses - Archive

Anonymous communication systems protect the privacy of their users by hiding who is communicating with whom. With the widespread use of the Internet, anonymity systems are all the more essential to support applications having strong privacy requirements such as intelligence gathering, military communications, or e-voting protocols. Anonymity systems must balance security and performance to remain popular with their users. In this work, we perform measurements on anonymity systems to improve their performance. We use the Vivaldi network coordinate system to efficiently map out the relative delays between hosts. Using this data, we create an overlay expander network topology that is …

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