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Articles 2161 - 2190 of 2429

Full-Text Articles in Physical Sciences and Mathematics

Probabilistic Localization Of Mobile Ad Hoc Networks, Rui Huang Dec 2006

Probabilistic Localization Of Mobile Ad Hoc Networks, Rui Huang

Computer Science and Engineering Dissertations - Archive

The mobile ad hoc network localization problem deals with estimating the physical location of the nodes that do not have a direct way (e.g., GPS) to determine their own locations. Being an enabling technology that is considered essential to the success of the future implementation of ad hoc networks in the real world, localization is a fundamental problem that needs to be solved with the best possible accuracy and efficiency. For this research, we study the localization problem in its various incarnations such as localization through static beacons, mobile beacons, dynamically deployed beacons and link longevity estimation based on relative …

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Runtime Optimization And Load Shedding In Mavstream: Design And Implementation, Balakumar Kendai Dec 2006

Runtime Optimization And Load Shedding In Mavstream: Design And Implementation, Balakumar Kendai

Computer Science and Engineering Theses - Archive

In data stream processing systems Quality of Service (or QoS) is extremely important. The system should try its best to meet the QoS requirements specified by a user. On account of this difference, unlike in a database management system, a query cannot be optimized once and executed. It has been shown that different scheduling strategies are useful in trading tuple latency requirements with memory and throughput requirements. In addition, data stream processing systems may experience significant fluctuations in input rates. In order to meet the QoS requirements of data stream processing, a runtime optimizer equipped with several scheduling and load …

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Compensation Of Photobleached Images For A Cell Dynamics System, Sowmya Gopinath Dec 2006

Compensation Of Photobleached Images For A Cell Dynamics System, Sowmya Gopinath

Computer Science and Engineering Theses - Archive

Progress in the field of medicine attributes to the discoveries in biology that require an extensive knowledge of cell dynamics. Intracellular Cell Dynamics Analysis System (ICellDAS) is a web based tool aimed at automating sub cellular particle motion estimation, tracking and mobility analysis. The purpose of this tool is to develop a better understanding of specific biology problems by visualizing biological data. For reliable analysis as well as visualization of cell dynamics, it is essential that the acquired images reflect the exact information of the specimen. The goal of the thesis is to design an interface for the ICellDAS project …

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Analyzing Differences In Color Variation Sensitivity Between Experts And Novices To Find A Differentiating Process In Pigmented Skin Lesion Diagnosis, Yu-Chin Chai Dec 2006

Analyzing Differences In Color Variation Sensitivity Between Experts And Novices To Find A Differentiating Process In Pigmented Skin Lesion Diagnosis, Yu-Chin Chai

Computer Science and Engineering Theses - Archive

Fatal skin lesions such as melanomas appear as having high color variation to experts but often as having low variation to novices. This thesis investigated if it is possible to find a function representing an expert's color variation sensitivity to skin lesions without explicitly requiring them to provide a diagnosis. Various pigmented skin images with either normal pigmentation or with diseased lesions were evaluated by experts and novices. To determine the best color space for lesion differentiation, an optimization process based on parametric color dimensions in a RGB color space was used to find the parameters of a color transformation …

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Using Part Of Speech Structure Of Text In The Prediction Of Its Readability, Jagadeesh Kondru Dec 2006

Using Part Of Speech Structure Of Text In The Prediction Of Its Readability, Jagadeesh Kondru

Computer Science and Engineering Theses - Archive

Readability formulas predict the reading difficulty associated with text. They typically output a U.S. school grade level that indicates the reading ability required of a person in order for him to comprehend that text. Ability to predict text readability is useful because it helps educators select appropriate texts for students and authors write texts accessible to the audience they target. Existing readability formulas are based on countable aspects of the text such as average sentence length and average word length. We propose a new readability formula, the Readability Index, which is based on the part-of-speech structure of sentences in a …

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Complementing Current Active Queue Management Schemes With Rechoke And Receiver-Window Modification (Rwm), Visvasuresh Govindaswamy Dec 2006

Complementing Current Active Queue Management Schemes With Rechoke And Receiver-Window Modification (Rwm), Visvasuresh Govindaswamy

Computer Science and Engineering Dissertations - Archive

Explicit Congestion Notification (ECN) and Active Queue Management (AQM) schemes have been proposed for present-day TCP/IP networks to better manage network congestion. ECN enabled AQMs were shown to have a promising advantage over existing drop-tail queues. However, when implemented, they were susceptible to the following problems: 1) the timeout mechanism or the duration of the reception of three duplicate acknowledgements (ACKs), due to early-dropped packets by these AQMs, delays the response time of TCP (in reducing the offered rate) 2) using ECN with these AQMs has its downsides: i) its messages may get delayed or dropped due to congestion in …

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Ca-Ole- A Collaborative And Adaptive Online Learning Environment, Paola Gomez Dec 2006

Ca-Ole- A Collaborative And Adaptive Online Learning Environment, Paola Gomez

Computer Science and Engineering Theses - Archive

Demand for online learning environments has grown in the past few years, and schools have been offering more distance courses to their students. Designing adequate online learning environments is considerably more challenging than conventional Face-To-Face courses; therefore traditional methods can not be used. This thesis proposes the creation of a Collaborative and Adaptive Online Learning Environment (CA-OLE) that provides a structure where instructors can combine their lesson materials with an adaptive system and collaborative tools. CA-OLE innovative approach consists of an adaptive framework that changes the way the learning materials prepared by instructors are presented to the students depending on …

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Personalizing (Re-Ranking) Web Search Results Using Information Present On A Social Network, Sushruth Puttaswamy Dec 2006

Personalizing (Re-Ranking) Web Search Results Using Information Present On A Social Network, Sushruth Puttaswamy

Computer Science and Engineering Theses - Archive

We describe a social search engine paradigm which can be built on top of a classic search engine (e.g. Google, Yahoo, etc.) and a social information network (such as FriendSter). In this thesis, the objective was to design algorithms and develop methods to efficiently combine information available in the underlying systems (Search Engine & Social Information Network) to better satisfy the search needs of a user. We are interested on how to efficiently employ social information to re-order a list of URLs retrieved by querying a search engine. The objective was to re-order the list of URLs in a way …

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Adaptive Load Balancing And Change Visualization For Webvigil, Subramanian Chelladurai Hari Hara Dec 2006

Adaptive Load Balancing And Change Visualization For Webvigil, Subramanian Chelladurai Hari Hara

Computer Science and Engineering Theses - Archive

There is a need for selective monitoring, the contents of web pages. Periodical visit for understanding changes to a web page is both inefficient and time consuming. WebVigiL is a system developed for automating the change detection and timely notification of HTML/XML pages based on user specified changes of interest. User interest, specified as a sentinel/profile, is automatically monitored by the system using a combination of learning-based and event-driven techniques. The first prototype concentrated on the functionality of the WebVigiL system. This thesis extends the WebVigiL system in a number of ways. The primary focus of this thesis is the …

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Efficient Main Memory Algorithms For Significant Interval And Frequent Episode Discovery, Sagar Hasmukh Savla Dec 2006

Efficient Main Memory Algorithms For Significant Interval And Frequent Episode Discovery, Sagar Hasmukh Savla

Computer Science and Engineering Theses - Archive

There is a considerable research on sequential mining of time-series data. Sensor-based applications such as MavHome require prediction of events for automating the environment using time-series data collected over a period of time. In these applications, it is important to predict tight and accurate intervals of interest to effectively automate the application. Also, detection of frequent patterns is needed for the automation of sequence of happenings. Although, there is a considerable body of work on sequential mining of transactional data, most of them deal with time point data and make several iterations over the entire data set for discovering frequently …

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Automated Software Testing Using Covering Arrays, Chinmay P. Jayaswal Dec 2006

Automated Software Testing Using Covering Arrays, Chinmay P. Jayaswal

Computer Science and Engineering Theses - Archive

Modern society is increasingly dependent on the quality of software systems. Software testing is a widely used approach to ensure software quality. Since exhaustive testing is impractical due to resource constraints, it is necessary to strike a balance between test efforts and quality assurance. Interaction testing is one approach to marrying these two qualities. It characterizes the system under test by a set of parameters and the respective test values (domain size) for each parameter. Instead of testing all possible combinations of values for all the parameters, interaction testing constructs a covering array as a test set to cover all …

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End-To-End Optimal Algorithms For Traffic Engineering, Failure Detection And Recovery In Connectionless Networks, Sukruth Srikantha Dec 2006

End-To-End Optimal Algorithms For Traffic Engineering, Failure Detection And Recovery In Connectionless Networks, Sukruth Srikantha

Computer Science and Engineering Theses - Archive

In this thesis we propose a novel scheme to achieve intra-domain Traffic Engineering (TE), Failure Detection and Recovery (FR) in connectionless networks. This scheme addresses rate adaptation, load balancing and stability issues of the OSPF protocol namely, network convergence times and route flapping. With the current default settings of the OSPF parameters, the network takes several tens of seconds to recover from a failure. The main component in this delay is the time required to detect the failure using the Hello protocol. Route flap is another undesirable phenomenon and needs to be eliminated to achieve greater stability and robustness in …

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Evading Existing Stepping Stone Detection Methods Using Buffering, Madhu Venkateshaiah Dec 2006

Evading Existing Stepping Stone Detection Methods Using Buffering, Madhu Venkateshaiah

Computer Science and Engineering Theses - Archive

To gain anonymity and complicate their apprehension, attackers launch attacks not from their own systems but from previously compromised systems called stepping stones. An effective way to detect stepping stones is by comparing of incoming and outgoing connections in a network to find correlations. For the sake of simplicity, earlier approaches ignore that an attacker can add chaff to a traffic stream. But in reality, the attacker may be able to modify applications to use cover traffic. We loosen some assumptions made by earlier researchers and propose a simple buffering technique that could be used by an attacker to evade …

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A Distributed Sensor Data Management Infrastructure Based On 802.15.4/Zigbee Networks, Tianqiang Li Dec 2006

A Distributed Sensor Data Management Infrastructure Based On 802.15.4/Zigbee Networks, Tianqiang Li

Computer Science and Engineering Theses - Archive

Wireless sensor networks consist of a certain number of autonomous devices with sensor, every device has certain detection functionality like light, temperature pressure etc. Communication by using the radio frequency make these spatially distributed devices feasible to oversee the activities in a large scale of area/space. 802.15.4/ZigBee networks are slated to run in the unlicensed frequencies. It is a packet-based radio protocol aimed at very low-cost, battery-operated widgets and sensors that can intercommunicate and send low-bandwidth data to each other. This thesis covers the content of a software solution of data management for an 802.15.4 networks. Its main contribution lies …

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The Formation And Obduction Of Ophiolites Since The Late Precambrian, Stacey Metzler Dec 2006

The Formation And Obduction Of Ophiolites Since The Late Precambrian, Stacey Metzler

Earth & Environmental Sciences Theses - Archive

Ophiolite formation and emplacement has been episodic since the Late Precambrian. This research study examines ophiolites that formed during the Cenozoic, Mesozoic, Paleozoic and Late Precambrian. The ophiolites were plotted on paleogeographic reconstructions using PALEOMAP Project maps, and the ophiolite localities were analyzed by their temporal distribution in relation to the tectonic framework in which they were emplaced. The ophiolites appear to show episodic events linked to global plate reorganization. These episodes coincide with collisional events from the supercontinents of Gondwana and Pangea. The primary mechanisms of formation and emplacement proved to be mid-ocean ridge systems and back arc basins …

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Calix[4]Arene-Based Synthetic Nanotubes, Voltaire Guanlao Organo Dec 2006

Calix[4]Arene-Based Synthetic Nanotubes, Voltaire Guanlao Organo

Chemistry & Biochemistry Dissertations - Archive

Nanoscale science and technology represents a tremendous opportunity to gain unprecedented insight into the unique phenomena that exists at the nanometer scale, and to use that knowledge to develop materials and devices with novel characteristics. This dissertation explores the unique properties of calix[4]arene-based synthetic nanotubes, the process of filling and characteristics of materials confined in one dimension. Chapter 1 provides an overview of recently developed nanoscale materials, particularly single-walled carbon nanotubes and their ability to encapsulate materials in a one-dimensional configuration. Molecules inside carbon nanotubes are reported to exhibit structural and dynamic properties that are not observed in the bulk. …

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Les For Wing Tip Vortex Around An Airfoil, Jiangang Cai Dec 2006

Les For Wing Tip Vortex Around An Airfoil, Jiangang Cai

Mathematics Dissertations - Archive

The wing tip vortex is very important because of its effects on the noise generation, blade/vortex interactions on helicopter blades, propeller cavitations on ships, and other fields. The objective of this work is to use the numerical simulation with high order accuracy and high resolution to investigate the formation and the near field evolution of a wing tip vortex at high Reynolds number. The computational domain includes a rectangular half-wing with a NACA 0012 airfoil section, a rounded wing tip and the surrounding boundaries. The wing has an aspect ratio of 0.75. The angle of attack is 10 degrees. The …

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Faint X‐Ray Structure In The Crab Pulsar Wind Nebula, F. D. Seward, W. H. Tucker, R. A. Fesen Dec 2006

Faint X‐Ray Structure In The Crab Pulsar Wind Nebula, F. D. Seward, W. H. Tucker, R. A. Fesen

Dartmouth Scholarship

We report on a Chandra observation of the Crab Nebula that gives the first clear view of the faint boundary of the Crab's X-ray-emitting pulsar wind nebula. There is structure in all directions. Fingers, loops, bays, and the south pulsar jet all indicate that either filamentary material or the magnetic field is controlling the relativistic electrons. In general, spectra soften as distance from the pulsar increases but do not change rapidly along linear features. This is particularly true for the pulsar jet. The termination of the jet is abrupt; the east side is close to an [O III] optical filament, …

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Holographic Patterning Of Polymer Dispersed Liquid Crystal Materials For Diffractive Optical Elements, Robert Allan Ramsey Dec 2006

Holographic Patterning Of Polymer Dispersed Liquid Crystal Materials For Diffractive Optical Elements, Robert Allan Ramsey

Physics Dissertations - Archive

Liquid crystals are a soft condensed matter phase that share properties with both isotropic liquids and crystalline solids. Composite materials formed from both low molecular weight liquid crystals and polymers are of both fundamental and technological importance. One method for preparing dispersions of polymers and liquid crystals is polymerization-induced phase separation. Photo-polymerization induced phase separation utilizes a mixture of a liquid crystal and a photo curable polymer contained between two indium tin-oxide (ITO) coated glass substrates. Irradiation of the homogeneous pre-polymer mixture initiates polymerization, which in turn induces a phase separation between the polymer and liquid crystal. Holographically patterned polymer …

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Search For Effective Natural Enemies Of Tetranychus Evansi In South And Southeast Brazil, Imeuda P. Furtado, Gilberto J. De Moraes, Serge Kreiter, Markus Knapp Dec 2006

Search For Effective Natural Enemies Of Tetranychus Evansi In South And Southeast Brazil, Imeuda P. Furtado, Gilberto J. De Moraes, Serge Kreiter, Markus Knapp

All Peer-Reviewed Publications

Tetranychus evansi Baker & Pritchard is an important pest of Solanaceae in several countries. Introduced accidentally to Africa, it presently occurs in many countries of that continent. In some of them, it is considered a key pest. The suspected area of origin of this mite is South America. The objective of the present study was to identify phytoseiid mites on solanaceous plants in association with T. evansi in south and southeast Brazil for introduction in the African continent for use in a classic biological control program. Almost 1,400 predatory mites of the family Phytoseiidae were collected, on 22 solanaceous species. …

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Mercury Exchange Between The Atmosphere And Low Mercury Containing Substrates, Mae Sexauer Gustin, Mark Engle, Jody Ericksen, Seth N. Lyman, Jelena Stamenkovic, Mei Xin Nov 2006

Mercury Exchange Between The Atmosphere And Low Mercury Containing Substrates, Mae Sexauer Gustin, Mark Engle, Jody Ericksen, Seth N. Lyman, Jelena Stamenkovic, Mei Xin

USU Uintah Basin Faculty Publications

Mercury is emitted to the air from Hg-enriched and low Hg-containing (natural background) substrates. Emitted Hg can be geogenic, or can be derived from the re-emission of Hg that was previously deposited to the soil from the atmosphere. Atmospheric Hg can be derived from natural and/or anthropogenic sources and can be deposited by wet or dry processes. It is important to understand the relative magnitude of emission, deposition, and re-emission of Hg associated with terrestrial ecosystems with natural background soil Hg concentrations because these landscapes cover large terrestrial surface areas. This information is also important for developing biogeochemical mass balances, …

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1021-0304_Mir_Irs, Michael C. Cushing Sep 2006

1021-0304_Mir_Irs, Michael C. Cushing

Publications and Research

No abstract provided.

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Identification Of Priority Areas In South America For Exploration Of Natural Enemies For Classical Biological Control Of Tetranychus Evansi (Acari: Tetranychidae) In Africa, Komi K.M. Fiaboe, Rafael L. Fonseca, Gilberto J. De Moraes, Callistus K.P.O. Ogol, Markus Knapp Sep 2006

Identification Of Priority Areas In South America For Exploration Of Natural Enemies For Classical Biological Control Of Tetranychus Evansi (Acari: Tetranychidae) In Africa, Komi K.M. Fiaboe, Rafael L. Fonseca, Gilberto J. De Moraes, Callistus K.P.O. Ogol, Markus Knapp

All Peer-Reviewed Publications

The red spider mite Tetranychus evansi Baker and Pritchard is a pest of tomato in East and Southern Africa. It is probably native to South America. Three models were established to identify priority areas for the search of natural enemies in South America for classical biological control of this pest in Africa. The models were based on the concept of "fundamental ecological niche", predicting regions in South America that have similar environmental conditions to areas where the mite is a problem in Africa, using Desktop-GARP (Genetic Algorithm for Rule-set Production). Based on the model established with data sets from Kenya …

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Investigation Of The Suitability Of The Biscatecholborate Anion As A Reductive Quencher For Photoexcited Ruthenium Polyphyridyl Complexes, Alper Yarasik Aug 2006

Investigation Of The Suitability Of The Biscatecholborate Anion As A Reductive Quencher For Photoexcited Ruthenium Polyphyridyl Complexes, Alper Yarasik

Chemistry & Biochemistry Theses - Archive

Ruthenium polypyridyl complexes [Ru(L-L)3]2+, (L-L = 1,10 - phenanthroline or 2,2'- bipyridine) which covalently linked to electron donor or acceptor units are frequently used in artificial photosystems because of their high emission quantum yields, long excited-state lifetimes, favorable redox properties and excellent chemical stability. The ruthenium dimer P, [(phen)2Ru(tatpp)Ru(phen)2][PF6]4, undergoes multiple photoreductions in the presence of donors such as triethylamine (TEA); however, large amount of donors (0.3 M) are required for efficient reductions. This explores the use of a anionic donor such as [B(cat)2]- with the hypothesis that ion-pairing will result in lower required concentration of the donor. Electrochemical data …

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Generalization And Enforcement Of Role-Based Access Control Using A Novel Event-Based Approach, Raman Adaikkalavan Aug 2006

Generalization And Enforcement Of Role-Based Access Control Using A Novel Event-Based Approach, Raman Adaikkalavan

Computer Science and Engineering Dissertations - Archive

Protecting information against unauthorized access is a key issue in information system security. Advanced access control models and mechanisms have now become necessary for applications and systems due to emerging acts, such as the Health Insurance Portability and Accountability Act (HIPAA) and the Sarbanes-Oxley Act. Role-Based Access Control (RBAC) is a viable alternative to traditional discretionary and mandatory access control. RBAC has been shown to be cost effective and is being employed in various application domains on account of its characteristics: rich specification, policy neutrality, separation of duty relations, principle of least privilege, and ease of management. Existing RBAC approaches …

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Learning State And Action Space Hierarchies For Reinforcement Learning Using Action-Dependent Partitioning, Mehran Asadi Aug 2006

Learning State And Action Space Hierarchies For Reinforcement Learning Using Action-Dependent Partitioning, Mehran Asadi

Computer Science and Engineering Dissertations - Archive

Autonomous systems are often dicult to program. Reinforcement learning (RL) is an attractive alternative, as it allows the agent to learn behavior on the basis of sparse, delayed reward signals provided only when the agent reaches desired goals. Recent attempts to address the dimensionality of RL have turned to principled ways of exploiting temporal abstraction, where decisions are not required at each step, but rather invoke the execution of temporally-extended activities which follow their own policies un- til termination. This leads naturally to hierarchical control architectures and associated learning algorithms. This dissertation reviews several approaches to temporal abstraction and hierarchical …

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Novel Approaches To Photoassisted Deposition Of Semiconductors And Nanocomposite Materials, Sashikala Somasundaram Aug 2006

Novel Approaches To Photoassisted Deposition Of Semiconductors And Nanocomposite Materials, Sashikala Somasundaram

Chemistry & Biochemistry Dissertations - Archive

This dissertation research begins with the use of TiO2-based photocatalysis for the reduction of metal ions with very negative reduction potentials. The indirect photocatalytic reduction of four metal ions: Cd2+, Zn2+, Mn2+, and Tl+ using formate radical anions generated in UV-irradiated aqueous TiO2 suspensions, is described. Using Tl+ as a model metal ion, a simple kinetics scheme was developed for the indirect reduction route, and the predictions from this model were shown to be in excellent agreement with experimental data. Titania-based photocatalysis was then used for the preparation of MSe/TiO2 "coupled" semiconductors. Heterogeneous photocatalysis using photoexcited TiO2 substrates was shown …

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Context Aware Energy Conservation In Pervasive Computing Environments, Prathiba Joseph Aug 2006

Context Aware Energy Conservation In Pervasive Computing Environments, Prathiba Joseph

Computer Science and Engineering Theses - Archive

Extending battery lifetime is one of the most critical and challenging problems in mobile systems. When the mobile device sounds a low battery alarm, the user is given an ultimatum to quickly find a power source or suspend work. The greatest utility of mobile devices is their ability to be used anywhere, and at anytime. But power limitations of these devices seem to hinder this goal. The ever-growing needs of mobile users for increased lifetime of wireless devices imply that emerging wireless systems must be more energy-efficient than ever before. Cyber foraging or remote resource exploitation may be an efficient …

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Evaluating Indexing And Routing Schemes For Spatial Queries In Sensor Networks, Raja Rajeshwari Anugula Aug 2006

Evaluating Indexing And Routing Schemes For Spatial Queries In Sensor Networks, Raja Rajeshwari Anugula

Computer Science and Engineering Theses - Archive

Recent advances in low-power sensing devices coupled with widespread availability of wireless ad-hoc networks, has fueled the development of sensor networks. These senor networks have various applications such as to monitor conditions at different locations (temperature, pressure, rainfall, vibrations etc.,), tracking of objects and so on. Each device is equipped with an energy source (usually with a battery), memory, CPU and communication bandwidth, which is severely constrained. Hence each sensor network is comprised of hardware for sensing, software for communication and computational algorithms. Spatial queries are commonly applied to sensor network, for example: "Find the highest temperature sensed in a …

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An Application Of Parallel And Distributed Computing Methods To Approximate Pattern Matching Of Genetic Regulatory Motifs, Tushar Kumar Jayantilal Aug 2006

An Application Of Parallel And Distributed Computing Methods To Approximate Pattern Matching Of Genetic Regulatory Motifs, Tushar Kumar Jayantilal

Computer Science and Engineering Theses - Archive

Bioinformatics is a relatively new scientific field concerned with providing computational means and support to research in molecular biology and genetics. It draws from many different areas of computer science, including database theory, algorithm design and analysis, and artificial intelligence, to name just a few. In many applications, such as one described in this thesis, a biologist is interested in locating a particular pattern, or sequence motif, in a given string or set of strings over the four-letter DNA alphabet. In this thesis we present an efficient approach to locating promoter and other regulatory sequences in entire genomes or in …

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