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Articles 1651 - 1680 of 2496

Full-Text Articles in Physical Sciences and Mathematics

Molecular Engineered Myoglobin With Unnatural Amino Acids As A Peroxidase, Kananke Sriyani Liyanage Jan 2012

Molecular Engineered Myoglobin With Unnatural Amino Acids As A Peroxidase, Kananke Sriyani Liyanage

Chemistry & Biochemistry Theses

Myoglobin (Mb) has been used as a model system to mimic other biologically important heme proteins like cytochrome P450 due to its ability to prepare mixed ligand complexes with different valencies, such as ferric, ferrous and ferryl species. It has been engineered to perform peroxidase, peroxygenase, monooxygenase and catalase activities. However, previous work on this area has shown that the distal histidine (H64) in the active of wild-type Mb is a critical residue, which destabilizes compound I, the reactive intermediate of the catalytic cycle (a ferryl ð-porphyrin radical cation). Therefore in this study we replaced H64 with a smaller residue, …

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The Variations Of Geomagnetic Energy And Solar Irradiance And Their Impacts On Earth's Upper Atmosphere, Yanshi Huang Jan 2012

The Variations Of Geomagnetic Energy And Solar Irradiance And Their Impacts On Earth's Upper Atmosphere, Yanshi Huang

Physics Dissertations

The primary energy sources of Earth's upper atmosphere are the solar irradiance and geomagnetic energy including Joule heating and particle precipitation. Various data and models are utilized to investigate the variations of energy inputs and their influences on the coupled thermosphere-ionosphere system. First, the Flare Irradiance Spectral Model (FISM) has been used and the data show that the solar irradiance enhancement has wavelength dependence during flare events, and it increased largest in the XUV range. NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) simulations for the X17.2-class flare event on October 28th, 2003 (X17.2) show that the impact of solar irradiance enhancement …

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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

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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Atomic Adsorptions On Actinide Surfaces: Pathways To Nuclear Energy, Dayla Renee Morrison Jan 2012

Atomic Adsorptions On Actinide Surfaces: Pathways To Nuclear Energy, Dayla Renee Morrison

Physics Theses

The generalized gradient approximation (GGA) to density functional theory (DFT) and hybrid density functional theory have been used to compute the layer-by-layer properties of γ-uranium (γ-U) in the (100) symmetry. Guided by bulk results which have been analyzed at six different levels of theory, the surface calculations have been performed at the non-magnetic level including spin-orbit coupling. The ground state bulk lattice constant and bulk modulus are found to be 3.46 A and 113.75 GPa, respectively at the non-magnetic with spin-orbit coupling level (NM+SOC) of theory. The monolayer displays a significant shrinking of the “effective” lattice constant of about 23.55% …

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Epigenetics Of Hoxc13 Endocrine Regulation And Its Role In Gene Expression And Tumorigenesis, Sahba Kasiri Jan 2012

Epigenetics Of Hoxc13 Endocrine Regulation And Its Role In Gene Expression And Tumorigenesis, Sahba Kasiri

Chemistry & Biochemistry Dissertations

HOX genes are a subgroup of homeobox containing gene superfamily and have crucial roles in cell proliferation, cell differentiation, and embryonic development. HOXC13, one of 39 identified human HOX genes, is involved in hair development and human leukemia. The regulatory mechanism that drives HOXC13 expression is mostly unknown. Our studies demonstrated that HOXC13 is transcriptionally activated by steroid hormone estrogen (17ß-estradiol; E2). The HOXC13 promoter contains several estrogen responsive elements (EREs), including ERE1 and ERE2, which are close to the transcription start site, and are associated with E2-mediated activation of HOXC13. Knockdown of estrogen receptors (ERs) ERɑ and ERß suppressed …

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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

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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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

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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From Phenotype To Genotype: A Structured Sparse Learning Framework For Imaging Genetics Studies, Hua Wang Jan 2012

From Phenotype To Genotype: A Structured Sparse Learning Framework For Imaging Genetics Studies, Hua Wang

Computer Science and Engineering Dissertations

Sparsity is one of the intrinsic properties of real-world data, thus sparse representation based learning models have been widely used to simplify data modeling and discover predictive patterns. By enforcing properly designed structured sparsity, one can unify specific data structures with the learning model. We proposed several novel structured sparsity learning models for multi-modal data fusion, heterogeneous tasks integration, and group structured feature selection. We applied our new structured sparse learning methods to the emerging imaging genetics studies by integrating phenotypes and genotypes to discover new biomarkers which are able to characterize neurodegenerative process in the progression of Alzheimer's disease …

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Multi Person Tracking And Querying With Heterogeneous Sensors, Shahina Ferdous Jan 2012

Multi Person Tracking And Querying With Heterogeneous Sensors, Shahina Ferdous

Computer Science and Engineering Dissertations

Tracking the location of a user is considered to be the most fundamental step for creating a context aware application, such as activity monitoring in an assistive environment. This problem becomes very challenging if there are multiple people involved in this scenario. The reason is that any multi-person environment, such as a hospital, demands simultaneous identification and localization mechanisms, thus making the system very complex. In this dissertation, we present a novel, less-intrusive system that uses RFIDs and sensors deployed at various locations of an assistive apartment to continuously track and identify every person in a multi-person assistive environment. Our …

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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

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

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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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

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

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

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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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

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

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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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

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

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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Point Of Gaze Applications For Assistive Interaction, Jonathan Walter Rich Jan 2012

Point Of Gaze Applications For Assistive Interaction, Jonathan Walter Rich

Computer Science and Engineering Theses

Eye tracking has many useful applications in human-machine interfaces and assistive technologies. Traditional input methods, such as the keyboard and mouse, are not practical in certain situations and can be completely ineffective for users with physical disabilities. Since many computing interfaces contain a strong visual component, it follows that knowledge of the user's point of gaze (PoG) can be extremely useful. Several approaches to PoG tracking have been described with various results and associated costs. Commercially available tracking devices have proven to be very useful for some disabled users, though often the systems can be cost prohibitive. Many computing applications …

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Development Of A Detached Vital Sign Home Monitoring Management System, Anderson John Jan 2012

Development Of A Detached Vital Sign Home Monitoring Management System, Anderson John

Computer Science and Engineering Theses

Patients coping with chronic illnesses are often inconvenienced with routine doctor visits for the sole purpose of conducting basic vital sign monitoring. Such visits tend to be disruptive, and are more so when the patient requires a lengthy commute or has a mobility disability. As technology progresses, advances in low powered integrated circuits and network connectivity has opened the doors to a new world of remote patient monitoring. This thesis explores the possibility of using low powered technology to develop a patient monitoring system that's completely detached, thus allowing patients to move around their homes while the monitoring continues. We …

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An Experiment In Developing Small Mobile Phone Applications Comparing On-Phone To Off-Phone Development, Tuan Anh Nguyen Jan 2012

An Experiment In Developing Small Mobile Phone Applications Comparing On-Phone To Off-Phone Development, Tuan Anh Nguyen

Computer Science and Engineering Theses

TouchDevelop represents a radically new mobile application development model, as TouchDevelop enables mobile application development on a mobile device. I.e., with TouchDevelop, the task of programming say a Windows Phone is shifted from the desktop computer to the mobile phone itself. We describe a first experiment on independent, non-expert subjects to compare programmer productivity using TouchDevelop vs. using a more traditional approach to mobile application development.

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Prominent Streaks Discovery On Blog Articles, Jijo John Philip Jan 2012

Prominent Streaks Discovery On Blog Articles, Jijo John Philip

Computer Science and Engineering Theses

We are surrounded by data in various forms such as instant messages, Twitter tweets, Facebook status updates, news, media, blogs and much more. Extracting meaning from such a massive collection of unstructured data would lead to interesting stories. Examples of such stories can be ``\emph{Who was the most popular actor in a particular month}''or ``\emph{Which diseases were people most concerned about in year 2008}''. In this thesis, we propose to discover popular entities mentioned in blog articles based on the concept of prominent streak. Given a sequence of values for a named entity (e.g., a person, a place, etc.), where …

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On Feasibility Of Fingerprinting Wireless Sensor Nodes Using Physical Properties, Xiaowei Mei Jan 2012

On Feasibility Of Fingerprinting Wireless Sensor Nodes Using Physical Properties, Xiaowei Mei

Computer Science and Engineering Theses

Fingerprinting wireless devices using physical properties has been recently suggested as an alternative for device identification and authentication. It has been found that the clock skew caused by the frequency discrepancy of the quartz crystals in different devices can be used as a reliable source for fingerprinting. Researchers have studied the application of the clock skew-based fingerprinting in sensor networks and claimed that it can detect fake identities, wormholes, and node replicas. However, the study in this paper draws a completely opposite conclusion, i.e., the clock skew of sensor nodes can be easily forged by adversaries to evade the detection. …

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Pushpop: A Card Game, Vishal Subramani Jan 2012

Pushpop: A Card Game, Vishal Subramani

Computer Science and Engineering Theses

In this thesis we have designed and implemented an Android card game called PushPop. This game is meant to stimulate the interest of kids in math learning. The Android game has cards with mathematical signs instead of the traditional suits. To reach the goal kids have to perform a lot of mathematical operations which helps them learn maths in a fun and effective way. A study was made to classify PushPop into the various games under the research umbrella of Game Theory. After the analysis we conclude that PushPop is a non-co-operative, symmetric, non-zero sum, simultaneously and imperfect information game …

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Comparing Web Application Scanners For Xss Attacks, Dengfeng Xia Jan 2012

Comparing Web Application Scanners For Xss Attacks, Dengfeng Xia

Computer Science and Engineering Theses

As software industry is paying increasing attention to web application security, various testing tools with black box testing feature have been developed. To better evaluate their performance, researchers have made efforts in several ways. Since XSS attack is one of the major attacks which can bring severe damages to victims, it is meaningful to pay specific attention to its testing process. However, many web application scanner evaluation projects make comparisons about various vulnerability types, and they are not dedicated to XSS issues enough. Their evaluations either use vulnerable applications in real life, or use test cases created by themselves, and …

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Shaping Network Topology For Privacy And Performance, Md Monjurul Hasan Jan 2012

Shaping Network Topology For Privacy And Performance, Md Monjurul Hasan

Computer Science and Engineering Theses

Anonymity systems provide privacy for Internet communication and are becoming popular. Unfortunately, users experience slow Internet connection through existing systems because paths used to route traffic are selected randomly without considering latency between nodes. In our work, we aim to design a better approach for selecting paths in anonymity systems with improved performance and without sacrificing privacy. We consider stratified topologies for our design where nodes are divided into three hops. We propose a scheme to build restricted network topologies on top of a stratified topology that maximizes throughput. First, we use Tabu Search to build latency-aware stratified restricted topologies …

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A Novel Scheme For Contact Predictions In Opportunistic Networks, Sujoy Kumar Bhattacharya Jan 2012

A Novel Scheme For Contact Predictions In Opportunistic Networks, Sujoy Kumar Bhattacharya

Computer Science and Engineering Theses

In the opportunistic network (ON) paradigm information is exchanged between two devices as they encounter each other. For such information exchange to take place the devices must know about the presence of other devices in the neighborhood. A very fundamental problem in ON is to predict the occurrence of a future opportunistic contact which is otherwise highly dynamic and unreliable. An accurate predictor which takes into account the long time history can benefit from multiple objectives. Such a predictor switches to the data transfer mode in anticipation of a contact. Also it maximizes the number of opportunistic contacts while spending …

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Control Framework Dynamic Walking Of A Bipedal Robot, Kishan Kumar Bhongale Prabhakar Prasad Jan 2012

Control Framework Dynamic Walking Of A Bipedal Robot, Kishan Kumar Bhongale Prabhakar Prasad

Computer Science and Engineering Theses

Despite significant progress in recent years, the capabilities of today's Humanoid robots still lack behind the walking abilities of humans in terms of competence, robustness, flexibility, and speed. Furthermore, unknown environmental conditions and related constraints imposed on the robot significantly increase the complexity of locomotion control and decision making for such systems, easily making planning-based approaches intractable. Part of the reason for this is that the control of a humanoid encompasses observation, processing the observed data, and decision making in terms of locomotion gait and body pose parameters. This key information derived from observations and internal robot information finally allows …

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Hydrological Visualization And Analysis System And Drought Related Feature Selection Based On Sectional Correlation Measurement, Piraporn Jangyodsuk Jan 2012

Hydrological Visualization And Analysis System And Drought Related Feature Selection Based On Sectional Correlation Measurement, Piraporn Jangyodsuk

Computer Science and Engineering Theses

Because of the larger data storage and the faster computational power, computer can process and store much finer resolution data. Aside from data analysis, data visualization is also an important task to understand the data. In this work, the Hydrological Visualization and Analysis System is developed to help both hydrologists and local people view and examine the high resolution hydrological data. Then, this data is analyzed to determine which variables are related to the change of drought condition in Arlington, Texas. A new correlation measurement method called sectional correlation is proposed and used as an objective function of the drought …

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Automatic Scheduler: A New Approach For Scheduling Rides, Amey Sudhir Bhalerao Jan 2012

Automatic Scheduler: A New Approach For Scheduling Rides, Amey Sudhir Bhalerao

Computer Science and Engineering Theses

Scheduling plays an important role in a person's life. Even computers use the concept of scheduling when it comes to processing jobs. Scheduling is important in cases normally when there is large data to process and manual scheduling is not an easy option to go for. A new concept of developing a scheduler has been discussed in this thesis. The algorithm was designed keeping in mind the Para Transit agencies that operate on federal funds to provide cheap transport service to the clients. The algorithm presented here is developed with the intention to reduce the delay faced by the client …

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