Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Physical Sciences and Mathematics (501)
- Engineering (301)
- Chemistry (128)
- Environmental Sciences (92)
- Earth Sciences (90)
-
- Life Sciences (88)
- Social and Behavioral Sciences (84)
- Computer Sciences (79)
- Education (71)
- Physics (67)
- Mechanical Engineering (66)
- Chemical Engineering (59)
- Analytical Chemistry (51)
- Geology (51)
- Electrical and Computer Engineering (47)
- Medicine and Health Sciences (44)
- Astrophysics and Astronomy (41)
- Artificial Intelligence and Robotics (40)
- Computer Engineering (39)
- Natural Resources and Conservation (38)
- Data Science (35)
- Operations Research, Systems Engineering and Industrial Engineering (34)
- Aerospace Engineering (33)
- Mathematics (33)
- Organic Chemistry (31)
- Statistics and Probability (29)
- Civil and Environmental Engineering (27)
- Condensed Matter Physics (27)
- Materials Science and Engineering (27)
- Physical Chemistry (26)
- Keyword
-
- Mechanical engineering (173)
- Electrical engineering (143)
- Computer science (121)
- Civil engineering (69)
- Industrial engineering (65)
-
- Mathematics (60)
- Petroleum engineering (56)
- Machine Learning (51)
- Aerospace engineering (50)
- Mining engineering (42)
- Chemical engineering (35)
- Educational technology (32)
- Energy (32)
- Artificial intelligence (31)
- Educational psychology (30)
- Higher education (30)
- Materials science (27)
- Educational administration (26)
- Curriculum development (23)
- Teacher education (23)
- Machine learning (22)
- Automotive engineering (21)
- Forestry (21)
- Biomedical engineering (20)
- Economics (20)
- Environmental engineering (20)
- Geology (20)
- Deep Learning (18)
- Artificial Intelligence (17)
- Educational leadership (17)
- Publication Year
- File Type
Articles 1831 - 1860 of 2865
Full-Text Articles in Entire DC Network
Estimate At Completion For Construction Projects, Yi Fang
Estimate At Completion For Construction Projects, Yi Fang
Graduate Theses, Dissertations, and Problem Reports (ETD)
Construction projects are complex and risky because there are so many variables that may affect their profitability especially in terms of their cost and schedule. The information provided by the measurement of progress, the expended dollars and the forecasting of the outcome of a construction project will provide valuable information as to how to proceed, the impacts, corrective action required, and the trade-offs necessary to maximize profits and minimize risk. This study focused on using different indicators to measure the schedule performance and cost performance of construction projects, and to predict final cost and duration by the moving average and …
Effect Of Breathing, Posture, And Air Velocity On Breathing Zone Gas Concentrations For Human Subjects In A Wind Tunnel, Ahmed R. El-Sotouhy
Effect Of Breathing, Posture, And Air Velocity On Breathing Zone Gas Concentrations For Human Subjects In A Wind Tunnel, Ahmed R. El-Sotouhy
Graduate Theses, Dissertations, and Problem Reports (ETD)
Industrial hygienists generally place air-sampling probes on the mid to upper torso of workers when attempting to determine inhaled concentrations. There is no convincing evidence that concentrations measured on the chest are equal to inhaled concentrations. To determine how well surrogate locations matched concentrations at the mouth (Cmouth), low concentrations of ethanol in nitrogen were released between the hands of standing and seated human subjects while they moved children's blocks back and forth over the source.;In all cases, each of four subjects stood or sat with their backs to the airflow in a wind tunnel because previous studies had established …
Application Of Machine Vision In Uavs For Autonomous Target Tracking, Joshua Patrick Effland
Application Of Machine Vision In Uavs For Autonomous Target Tracking, Joshua Patrick Effland
Graduate Theses, Dissertations, and Problem Reports (ETD)
This research presents experimental results for the application of Machine Vision (MV) techniques to address the problem of target detection and tracking. The main objective is the design of a prototype "UAV" surveillance environment to emulate real-life conditions. The model environment for this experiment consists of a target simulated by a small electric train system, located at "ground" level, and a MV camera mounted on a motion-based apparatus located directly above the model setup. This system is meant to be a non-flying mockup of an aerial robot retrofitted with a MV sensor. Therefore, the final design is a two degree-of-freedom …
Heuristics For The Dynamic Facility Layout Problem With Unequal Area Departments, Artak Hakobyan
Heuristics For The Dynamic Facility Layout Problem With Unequal Area Departments, Artak Hakobyan
Graduate Theses, Dissertations, and Problem Reports (ETD)
The facility layout problem (FLP) is a well researched problem of finding positions of departments on a plant floor such that departments do not overlap and some objective(s) is (are) optimized. In this dissertation, the FLP with unequal area rectangular shaped departments is considered, when material flows between departments change during the planning horizon. This problem is known as the dynamic FLP. The change in material flows between pairs of departments in consecutive periods may require rearrangements of departments during the planning horizon in order to keep material handling costs low. The objective of our problem is to minimize the …
Feasibility And Optimum Design Study Of A Low Speed Wind Turbine Rotor System For Underground Communication Power, John E. Harman
Feasibility And Optimum Design Study Of A Low Speed Wind Turbine Rotor System For Underground Communication Power, John E. Harman
Graduate Theses, Dissertations, and Problem Reports (ETD)
A need has been recognized to have battery charging capabilities in underground mines, independent of outside AC power sources. In the event of emergency, the radios located throughout underground mines stay charged for periods insufficient to ensure the safety of trapped mineworkers. Air is always being distributed to supply oxygen and to dilute explosive gases throughout all sections of the mine. An idea to charge the batteries using the energy stored in the moving air was recently proposed. The feasibility of using a small wind turbine to charge the batteries in this airlflow will be addressed by this thesis. If …
Automatic Control And Fault Diagnosis Of Mems Lateral Comb Resonators, Afshin Izadian
Automatic Control And Fault Diagnosis Of Mems Lateral Comb Resonators, Afshin Izadian
Graduate Theses, Dissertations, and Problem Reports (ETD)
Recent advancements in microfabrication of Micro Electro Mechanical Systems have made MEMS an important part of many applications such as safety and sensor/control devices. Miniature structure of MEMS makes them very sensitive to the environmental and operating conditions. In addition, fault in the device might change the parameters and result in unwanted behavioral variations. Therefore, imperfect device structure, fault and operating point dependencies suggest for active control of MEMS.;This research is focused on two main areas of control and fault diagnosis of MEMS devices. In the control part, the application of adaptive controllers is introduced for trajectory control of the …
Adaptive Frame Selection For Enhanced Face Recognition In Low-Resolution Videos, Raghavender Reddy Jillela
Adaptive Frame Selection For Enhanced Face Recognition In Low-Resolution Videos, Raghavender Reddy Jillela
Graduate Theses, Dissertations, and Problem Reports (ETD)
Performing face detection and recognition in low-resolution videos (e.g., surveillance videos) is a challenging task. To enhance the biometric content in these videos, image-level and score-level fusion techniques can be used to consolidate the information available in successive low-resolution frames. In particular, super-resolution can be used to perform image-level fusion while the simple sum-rule can be used to perform score-level fusion. In this thesis we propose a technique which adaptively selects low-resolution frames for fusion based on optical flow information. The proposed technique automatically disregards frames that may cause severe artifacts in the super-resolved output by examining the optical flow …
Power System Damping Controllers Design Using A Backstepping Control Technique, Ali Karimi
Power System Damping Controllers Design Using A Backstepping Control Technique, Ali Karimi
Graduate Theses, Dissertations, and Problem Reports (ETD)
The objective of this dissertation is to design and coordinate controllers that will enhance transient stability of power systems subject to large disturbances. Two specific classes of controllers have been investigated, the first one is a type of supplementary signals added to the excitation systems of the generating units, and the second is a type of damping signal added to a device called a Static Var Compensator that can be placed at any node in the system. To address a wide range of operating conditions, a nonlinear control design technique, called backstepping control, is used. While these two types of …
Design And Performance Analysis Of Electric Vehicles Fed By Multiple Fuel Cells, Pardis Khayyer
Design And Performance Analysis Of Electric Vehicles Fed By Multiple Fuel Cells, Pardis Khayyer
Graduate Theses, Dissertations, and Problem Reports (ETD)
Recent advances in fuel cell developments have introduced them to many applications such as hybrid electric vehicles and heat/power cogenerations. They bring the advantage of clean energy and decrease the dependency on imported oil by providing fuel efficient devices in many applications such as electric vehicles. Conventional designs of hybrid fuel cell vehicles make use of a single fuel cell power source and a storage device to provide the base load and transients in various driving cycles. This thesis proposes a new configuration of multiple fuel cell power sources in hybrid fuel cell vehicles. Fuel cells are downsized in this …
Effect Of Circulation Control Blowing Slots On Stall Angles Of A 10:1 Elliptical Airfoil, Jonathan Kweder
Effect Of Circulation Control Blowing Slots On Stall Angles Of A 10:1 Elliptical Airfoil, Jonathan Kweder
Graduate Theses, Dissertations, and Problem Reports (ETD)
Circulation control is a high-lift methodology that can be used on the wing of an aircraft. This technology has been in the research and development phase for over sixty years primarily for fixed wing aircraft when the early models were referred to as "blown flaps." Circulation control works by increasing the near surface velocity of the airflow over the leading edge and/or trailing edge of a specially designed aircraft wing using a series of blowing slots that eject high velocity jets of air. The wing has a rounded trailing edge, and ejects the air tangentially, through these slots inducing the …
Application Of Multi-Agents To Power Distribution Systems, Koushaly Nareshkumar
Application Of Multi-Agents To Power Distribution Systems, Koushaly Nareshkumar
Graduate Theses, Dissertations, and Problem Reports (ETD)
The electric power system has become a very complicated network at present because of re-structuring and the penetration of distributed energy resources. In addition, due to increasing demand for power, issues such as transmission congestion have made the power system stressed. A single fault can lead to massive cascading effects, affecting the power supply and power quality. An overall solution for these issues can be obtained by a new artificial intelligent mechanism called the multi-agent system. A multi-agent system is a collection of agents, which senses the environmental changes and acts diligently on the environment in order to achieve its …
Modeling, Identification And Control Of A Cold Flow Circulating Fluidized Bed, Rupendranath Panday
Modeling, Identification And Control Of A Cold Flow Circulating Fluidized Bed, Rupendranath Panday
Graduate Theses, Dissertations, and Problem Reports (ETD)
Circulating fluidized bed (CFB) is used extensively in petrochemical industries especially for fluid catalytic cracking, coal combustion or gasification and various other chemical processes. In this work, data are used to identify cold flow circulating fluidized bed's (CFCFB) multiple sub models and to combine them into a single nonlinear model such that solids circulation rate can be estimated from the move air flow and riser aeration fed to the device, and the total pressure drop developed across the riser at extremely different experimental conditions.;The present work begins with a complete black box model of a state-space description arising from the …
Parasitic Drag Analysis Of A High Inertia Flywheel Rotating In An Enclosure, Chad C. Panther
Parasitic Drag Analysis Of A High Inertia Flywheel Rotating In An Enclosure, Chad C. Panther
Graduate Theses, Dissertations, and Problem Reports (ETD)
There are currently millions of people throughout the world who live in isolated, rural communities without electricity. An ongoing effort has been initiated to provide reliable power to such communities. These efforts are being made to utilize renewable energy sources such as wind and solar power to solve this problem. Renewable energy sources can be both intermittent and unpredictable. Thus, an effective energy storage system is sought to store excess energy when available to disperse during times of scarcity.;The use of a high-inertia flywheel was proposed as a means of energy storage due to its simplicity, low cost, and reliability. …
Investigation Of Selenium And Arsenic In Coal-Mining Associated Rocks And Sediments Using Ultrasonic And Sequential Extractions Techniques, Innocent Pumure
Investigation Of Selenium And Arsenic In Coal-Mining Associated Rocks And Sediments Using Ultrasonic And Sequential Extractions Techniques, Innocent Pumure
Graduate Theses, Dissertations, and Problem Reports (ETD)
Ultrasound extraction was used to compare the accelerated release rates of arsenic and selenium from pulverized rocks associated with mountain-top removal/valley fill method of coal mining. The kinetic studies demonstrated that the release rates are dependent on rock lithology as well as the total concentrations found in the rocks. Se (IV) was found to be stable under ultrasonic irradiation (200 W/cm2) but As (III) was quickly oxidized to As (V). Rocks such as BT700 were found to have more Se (IV) compared to Se (VI) and others such as BT571 were found to contain more Se (VI) than Se (IV).;Continuous …
Efficiency Optimization And Control Of Permanent Magnet Synchronous Brushless Motors In Three-Phase Pulse Width Modulated Voltage Source Inverter Drives, Olusegun Richard Solomon
Efficiency Optimization And Control Of Permanent Magnet Synchronous Brushless Motors In Three-Phase Pulse Width Modulated Voltage Source Inverter Drives, Olusegun Richard Solomon
Graduate Theses, Dissertations, and Problem Reports (ETD)
In high performance drives where it is desirable to exploit the usefulness of reluctance torque and machine saliency, permanent magnet synchronous brushless motors are machines of choice. However, speed control of these machines especially in the flux weakening region becomes more complex due to the non-linear coupling among the winding currents as well as the nonlinearity present in the torque. While numerous research efforts in the past have considered control and efficiency improvements of induction motors, and synchronous motors with field windings, research efforts in developing an efficiency optimization and control strategy applicable to all salient-type permanent magnet synchronous brushless …
Investigation Of Mud Filtrate Invasion Using Computational Fluid Dynamics, Suyoun Won
Investigation Of Mud Filtrate Invasion Using Computational Fluid Dynamics, Suyoun Won
Graduate Theses, Dissertations, and Problem Reports (ETD)
Despite continued research and developments in logging technology, logs processed by the prevalent standard methods continue to be influenced by formation damage and mud filtrate invasions. The mud-filtrate invasion and related formation damage due to drilling fluids can result in the misinterpreted values of rock and fluid properties in the reservoir which can affect the well plan. Well planning with accurate information of target reservoir is a very important part of any drilling procedure, as it would not only optimize drilling operation and completion but also maximizes production of oil and gas.;To produce hydrocarbons effectively, the wellbore must communicate with …
Parsimony-Based Genetic Algorithm For Haplotype Resolution And Block Partitioning, Nadezhda A. Sazonova
Parsimony-Based Genetic Algorithm For Haplotype Resolution And Block Partitioning, Nadezhda A. Sazonova
Graduate Theses, Dissertations, and Problem Reports (ETD)
This dissertation proposes a new algorithm for performing simultaneous haplotype resolution and block partitioning. The algorithm is based on genetic algorithm approach and the parsimonious principle. The multiloculs LD measure (Normalized Entropy Difference) is used as a block identification criterion. The proposed algorithm incorporates missing data is a part of the model and allows blocks of arbitrary length. In addition, the algorithm provides scores for the block boundaries which represent measures of strength of the boundaries at specific positions. The performance of the proposed algorithm was validated by running it on several publicly available data sets including the HapMap data …
Nonlinear Approximation Using Blaschke Polynomials, Daniel Van Vliet
Nonlinear Approximation Using Blaschke Polynomials, Daniel Van Vliet
Graduate Theses, Dissertations, and Problem Reports (ETD)
This dissertation, entitled Nonlinear Approximation Using Blaschke Polynomials, is motivated by questions arising from Empirical Mode Decomposition (EMD). EMD is a signal processing method which decomposes input signals into components called intrinsic mode functions (IMFs). These IMFs often have the desirable property that the instantaneous frequency of their analytic signals is positive. However, this is not always the case.;The first two chapters are introductions to approximation in general, and Empirical Mode Decomposition, respectively.;The third chapter presents a characterization of which analytic signals have the property of non-negative instantaneous frequency. These 'analytic signals with non-negative instantaneous frequency' (ASNIFs) are described using …
Multivariable Robust Control Of A Simulated Hybrid Solid Oxide Fuel Cell Gas Turbine Plant, Alex Tsai
Multivariable Robust Control Of A Simulated Hybrid Solid Oxide Fuel Cell Gas Turbine Plant, Alex Tsai
Graduate Theses, Dissertations, and Problem Reports (ETD)
This work presents a systematic approach to the multivariable robust control of a hybrid fuel cell gas turbine plant. The hybrid configuration under investigation built by the National Energy Technology Laboratory comprises a physical simulation of a 300kW fuel cell coupled to a 120kW auxiliary power unit single spool gas turbine. The public facility provides for the testing and simulation of different fuel cell models that in turn help identify the key difficulties encountered in the transient operation of such systems. An empirical model of the built facility comprising a simulated fuel cell cathode volume and balance of plant components …
Color Space Analysis For Iris Recognition, Matthew K. Monaco
Color Space Analysis For Iris Recognition, Matthew K. Monaco
Graduate Theses, Dissertations, and Problem Reports (ETD)
This thesis investigates issues related to the processing of multispectral and color infrared images of the iris. When utilizing the color bands of the electromagnetic spectrum, the eye color and the components of texture (luminosity and chromaticity) must be considered. This work examines the effect of eye color on texture-based iris recognition in both the near-IR and visible bands. A novel score level fusion algorithm for multispectral iris recognition is presented in this regard. The fusion algorithm - based on evidence that matching performance of a texture-based encoding scheme is impacted by the quality of texture within the original image …
Design And Real-Time Control Of Shipboard Power System Testbed, Pradeep Pant
Design And Real-Time Control Of Shipboard Power System Testbed, Pradeep Pant
Graduate Theses, Dissertations, and Problem Reports (ETD)
The objective of this thesis is to design and test a small scale testbed for the all-electric shipboard power distribution system. Shipboard power system is increasingly becoming more reconfigurable, and multi-agent systems are developed to automate routine operation and emergency reconfiguration. Underlying algorithms of these systems have been verified using software simulation tools. However, these simulators run in soft realtime by using simple mathematical models to represent the physical system. These models do not incorporate every aspect of the physical system. A testbed provides a cost effective physical environment to verify these algorithms and control techniques in the real world. …
Exploring The Use Of Human Metrology For Biometric Recognition, Nikhil Mallikarjun Reddy Burri
Exploring The Use Of Human Metrology For Biometric Recognition, Nikhil Mallikarjun Reddy Burri
Graduate Theses, Dissertations, and Problem Reports (ETD)
This thesis explores the possibility of incorporating human body measurements in a biometric framework. While metrological features have been used for identifying persons in the late 19th century, there is limited work in automating this process for surveillance applications. We first establish the relevance of using metrological features in biometric systems by studying two anthropometric data-sets (NASA and NHANES). We then propose a technique to automatically extract a subset of these measurements from a video sequence. A robust segmentation technique (HMMF) to detect moving pixels corresponding to human objects is used in the first stage. Next, we use Active Contours …
User Habitation In Keystroke Dynamics Based Authentication, Qi Cheng
User Habitation In Keystroke Dynamics Based Authentication, Qi Cheng
Graduate Theses, Dissertations, and Problem Reports (ETD)
Most computer systems use usernames and passwords for authentication and access control. For long, password security has been framed as a tradeoff between user experience and password security. Trading off one for the other appears to be an inevitable dilemma for single password based security applications. As a new biometric for authenticating access, keystroke dynamics offers great promises in hardening the password mechanism. Our research first investigate the keystroke dynamics based password security by conducting an incremental study on user's habituation process for keystroke dynamics analysis using two distinct types of passwords. The study shows that (1) long and complex …
Fractal Analysis Of Fingerprints, John C. Deal
Fractal Analysis Of Fingerprints, John C. Deal
Graduate Theses, Dissertations, and Problem Reports (ETD)
Current methods for comparing fingerprints have weaknesses that have opened them to criticism. Current methods concentrate on the comparison of minutia in the print either manually or with the assistance of a computer algorithm. This causes these methods to depend highly on the presence of minutia and their relationship to one another. Absence or rotations of minutia can prevent current methods form making accurate comparisons. The goal of this process is to develop a new method for analyzing fingerprints that addresses many of the concerns with current methods.;The developed process uses an iterated function sequence (IFS) to convert the image …
Comparative Study In Stereographic Reading, Alberto E. Santiago
Comparative Study In Stereographic Reading, Alberto E. Santiago
Graduate Theses, Dissertations, and Problem Reports (ETD)
Viewing a Single Image Random Dot Stereogram (SIRDS) or autostereogram picture requires careful concentration from the viewer. The concentration necessary to perceive depth may affect the performance of the reading process. We are studying if information perceived by way of a stereogram is better retained in memory compared to normal reading without stereo vision. To measure subject's memory performance we administered a questionnaire after a stereographic experience containing a readable story. We discovered that exposing subjects to stereographic information has a slight advantage on the ability to remember precise details of the information read.
Use Of Native Seed Mixtures To Improve Erosion Control And Wildlife Habitat On Log Landings Following Timber Harvest In The Upper Elk Watershed Of West Virginia, Lisa R. Tager
Graduate Theses, Dissertations, and Problem Reports (ETD)
Foresters in West Virginia follow BMP guidelines by reseeding retired log landings with inexpensive grasses that quickly provide erosion control. However, these grasses typically are not native nor do they provide high quality forage for wildlife. I developed 3 native seed mixtures for log landing reclamation that would maintain sediment control, as well as enhance wildlife habitat. These mixtures included an erosion control mixture, a wildlife mixture, and a wildflower mixture. I assessed sediment control, biomass production, vegetation structure, forage quality, and small mammal usage of my native mixtures and a commonly used, nonnative traditional mixture in 2005 and 2006. …
Market Risk Analysis Of Coal Liquefaction, Huan Mei
Market Risk Analysis Of Coal Liquefaction, Huan Mei
Graduate Theses, Dissertations, and Problem Reports (ETD)
This study addresses the risks associated with coal liquefaction using a market risk simulation approach. The study can be divided into four phases: (i) identify the sources of risk, (ii) examine the relationships among different sources that cause the risk, (iii) estimate the risk level based on the sources of risk using statistical and financial method and (iv) provide conclusions and recommendations for risk analysis.;Market risk is considered the most important risk for commercial scale coal liquefaction projects and is one of the biggest obstacles to commercialization. This study analyses market risk and discusses methods to lower this type of …
Three-Dimensional, High Resolution, Computerized Ionospheric Tomographic Imaging And Computational Modeling Of An Artificial Ionospheric Cavity, Craig A. Selcher
Three-Dimensional, High Resolution, Computerized Ionospheric Tomographic Imaging And Computational Modeling Of An Artificial Ionospheric Cavity, Craig A. Selcher
Graduate Theses, Dissertations, and Problem Reports (ETD)
Tomographic techniques use line integral measurements to reconstruct local values of the measured parameter. These techniques have been applied to the ionosphere by using radio transmissions to measure the integral of electron density between a satellite and a chain of ground-based receiving stations. The resultant reconstructions form a two-dimensional map of the electron density in the plane of the satellite/receiver chain. Insufficient quantity of receivers and not having a complete range of accessible look angles with the available receivers are responsible for the non-uniqueness in the reconstructions. The limited look angle problem can be alleviated by making use of alternative …
Selected Topics In Video Coding And Computer Vision, Congxia Dai
Selected Topics In Video Coding And Computer Vision, Congxia Dai
Graduate Theses, Dissertations, and Problem Reports (ETD)
Video applications ranging from multimedia communication to computer vision have been extensively studied in the past decades. However, the emergence of new applications continues to raise questions that are only partially answered by existing techniques. This thesis studies three selected topics related to video: intra prediction in block-based video coding, pedestrian detection and tracking in infrared imagery, and multi-view video alignment.;In the state-of-art video coding standard H.264/AVC, intra prediction is defined on the hierarchical quad-tree based block partitioning structure which fails to exploit the geometric constraint of edges. We propose a geometry-adaptive block partitioning structure and a new intra prediction …
Validation Of A New Technique Of Production Data Analysis For Single And Multi-Layer Formations Under Controlled Environment, Domingo A. Mata
Validation Of A New Technique Of Production Data Analysis For Single And Multi-Layer Formations Under Controlled Environment, Domingo A. Mata
Graduate Theses, Dissertations, and Problem Reports (ETD)
Intelligent Production Data Analysis - IPDA, is a new methodology for Reservoir Characterization based only on monthly production rate data. This technique combines conventional methods of production data analysis (decline curve analysis, type curve matching and history matching) with intelligent systems. The study targets the validation of this methodology under a controlled environment, attempting three main objectives: Identifying Sweet Spots, Forecasting Reserves and recognizing under-performer wells.;The study investigates the behavior of five different reservoirs, modeled using a commercial simulator. The structure, parameters and heterogeneity of each configuration was inspired by existing formations. Records of production rate data were generated from …