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Articles 5671 - 5700 of 11510

Full-Text Articles in Engineering

Resistance Prediction For Asymmetrical Configurations Of High-Speed Catamaran Hull Forms, Srikanth Asapana Dec 2015

Resistance Prediction For Asymmetrical Configurations Of High-Speed Catamaran Hull Forms, Srikanth Asapana

Theses and Dissertations

Predicting the resistance of a high-speed catamaran has been of interest to naval architects for the last three decades. Even though considerable amount of research has been carried out in this area, there remains a degree of uncertainty in the accurate resistance prediction of catamaran hull forms in the early design stage. Researches carried out so far have generally ignored the resistance characteristics of unconventional and unsymmetrical catamaran hull forms. This thesis attempts to undertake a comparative analysis of resistance characteristics between newly developed unconventional catamaran hull forms of different configurations derived from existing conventional NPL series of round bilge …

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An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor Dec 2015

An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor

Theses and Dissertations

Numeric hydrologic models can aid in water resource management by providing predictive simulations of water behavior. As computers become more advanced, the models developed also become more complex using more data to represent larger areas for forecasting hydrologic behavior. Unfortunately, as the simulations use more data, the output often becomes difficult to manage and share without investing time and effort into setting up server environments or decreasing the quality of the output to compensate for an efficient and effective user experience. A proposed solution to facilitate the accessibility of massive hydrologic model output is through the web-based visualization tool developed …

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Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard Dec 2015

Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard

Theses and Dissertations

Field Programmable Gate Arrays (FPGAs) are being used more frequently in space applications because of their reconfigurability and intensive processing capabilities. FPGAs in environments like space are susceptible to ionizing radiation which can cause Single Event Upsets (SEUs) in the FPGA's configuration memory. These upsets may cause the programmed user design on the FPGA to deviate from its normal behavior. Space missions cannot afford to allow important data processing applications to become corrupted due to these radiation upsets.Configuration scrubbing is an upset mitigation technique that detects and corrects upsets in an FPGA's configuration memory. Configuration scrubbing periodically monitors an FPGA's …

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Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods Dec 2015

Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods

Theses and Dissertations

Land cover change over time can be a useful indicator of variations in a watershed, such as the patterns of drought in an area. I present a case study using remotely sensed images from Landsat satellites for over a 30-year period to generate classifications representing land cover categories, which I use to quantify land cover change in the watershed areas that contribute to Malheur, Mud, and Harney Lakes. I selected images, about every 4 to 6 years from late June to late July, in an attempt to capture the peak vegetation growth and to avoid cloud cover. Complete coverage of …

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Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes Dec 2015

Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes

Theses and Dissertations

This study was designed to evaluate the ability of vertical drains to prevent liquefaction and limit associated settlement. Drain performance was investigated using full-scale tests with vertical drains in liquefiable sand using a laminar shear box with acceleration time histories applied at the base. Performance of the sand box with drains in these tests was compared with performance of the sane box without drains in previous tests. The test data was also used to create case histories which can be used for further research and calibration of computer models. Although some investigations regarding vertical drains have been performed with centrifuge …

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Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo Dec 2015

Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo

Theses and Dissertations

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force-deflection relationship for the abutment wall. Current design codes make no allowance for skew effects on passive force; however, large scale field tests indicate that there is a substantial reduction in peak passive force as skew angle increases. A reduction in passive force also reduces the transverse shear resistance on the abutment. The purpose of this study is to validate three-dimensional model using PLAXIS 3D, against large scale test results performed at Brigham Young University and to develop a set of calibrated finite element models. The …

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Galvanic Corrosion Of Magnesium Coupled To Steel At High Cathode-To-Anode Area Ratios, Dila Ram Banjade Dec 2015

Galvanic Corrosion Of Magnesium Coupled To Steel At High Cathode-To-Anode Area Ratios, Dila Ram Banjade

Theses and Dissertations

In this study, the impact of galvanic coupling of magnesium to steel on the corrosion rate, surface morphology, and surface film formation was investigated. In particular, the role of self-corrosion was quantified as previous studies showed discrepancies between model predictions and experimental results that were likely due to significant self-corrosion. This experimental study examined the corrosion of Mg coupled to steel in 5 wt% NaCl at cathode-to-anode area ratios that ranged from 5 to 27. Results showed that self-corrosion was significant and accounted for, on average, one-third of total corrosion. Moreover, self-corrosion varied with time and cathode size, and was …

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Enhanced-Resolution Processing And Applications Of The Ascat Scatterometer, Richard D. Lindsley Dec 2015

Enhanced-Resolution Processing And Applications Of The Ascat Scatterometer, Richard D. Lindsley

Theses and Dissertations

The ASCAT scatterometer measures the Earth surface microwave radar backscatter in order to estimate the near-surface winds over the oceans. While the spatial resolution of the conventional applications is sufficient for many purposes, other geoscience applications benefit from an improved spatial resolution. Specialized algorithms may be applied to the scatterometer data in order to reconstruct the radar backscatter on a high-resolution grid. Image reconstruction requires the spatial response function (SRF) of each measurement, which is not reported with the measurement data. To address this need, I precisely model the SRF incorporating (1) the antenna beam response, (2) the processing performed …

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Characterizing The Effects Of Capillary Flow During Liquid Composite Molding, Michael Ray Morgan Dec 2015

Characterizing The Effects Of Capillary Flow During Liquid Composite Molding, Michael Ray Morgan

Theses and Dissertations

As the aerospace industry continues to incorporate composites into its aircraft, there will be a need for alternative solutions to the current autoclaving process. Liquid composite molding (LCM) has proven to be a promising alternative, producing parts at faster rates and reduced costs while retaining aerospace grade quality. The most important factor of LCM is controlling the resin flow throughout the fiber reinforcement during infusion, as incomplete filling of fibers is a major quality issue as it results in dry spots or voids. Void formation occurs at the resin flow front due to competition between viscous forces and capillary pressure. …

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Stochastic Simulation Of Lagrangian Particle Transport In Turbulent Flows, Guangyuan Sun Dec 2015

Stochastic Simulation Of Lagrangian Particle Transport In Turbulent Flows, Guangyuan Sun

Theses and Dissertations

This dissertation presents the development and validation of the One Dimensional Turbulence (ODT) multiphase model in the Lagrangian reference frame. ODT is a stochastic model that captures the full range of length and time scales and provides statistical information on fine-scale turbulent-particle mixing and transport at low computational cost. The flow evolution is governed by a deterministic solution of the viscous processes and a stochastic representation of advection through stochastic domain mapping processes. The three algorithms for Lagrangian particle transport are presented within the context of the ODT approach. The Type-I and -C models consider the particle-eddy interaction as instantaneous …

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Cockpit Video Recorder & Streaming For Training Purposes, Ruthvik Adloori Dec 2015

Cockpit Video Recorder & Streaming For Training Purposes, Ruthvik Adloori

Theses and Dissertations

This paper is my Master's Thesis which is based on Cockpit Voice and Video Recorder which is an enhancement to the current Cockpit Voice Recorder. The main aim of my project is to use the system for training of pilots about cockpit functions and different in flight scenarios. The key factors for efficient Human-Machine systems such as situation awareness, decision making, risk management are studied in this thesis. The complexity in the design and the way to override such complexity is also demonstrated in this paper. A g1 impse of understanding through emotions is also discussed as an advantage in …

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Impact Of Constructing A Low Crested Weir In Cape Canaveral On Flushing In The Banana River, Atousa Saberi Dec 2015

Impact Of Constructing A Low Crested Weir In Cape Canaveral On Flushing In The Banana River, Atousa Saberi

Theses and Dissertations

The purpose of this study is to determine the extent to which constructing a low crested weir adjacent to Port Canaveral improves ushing in the Banana River. The Banana River is a 50 km long sub-basin of Indian River Lagoon (IRL), located between Cape Canaveral and Merritt Island in Brevard County. Although Port Canaveral locks connect the Banana River to the ocean, the locks remain closed when there are no passing vessels; therefore, it has limited circulation and a long ushing time. Declining water quality can be linked to recent high mortality events of di erent species living in the …

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Contribution To T He Onboard Context Sensitive Information System ( Of Commercial Aircraft, Wei Tan Dec 2015

Contribution To T He Onboard Context Sensitive Information System ( Of Commercial Aircraft, Wei Tan

Theses and Dissertations

Pilots currently use paper-based documentation and electronic systems (e.g., Electronic Centralized Aircraft Monitor (ECAM) for Airbus, and Engine Indication and Crew Alerting System (EICAS) for Boeing) to help them perform procedures to ensure safety, efficiency and comfort on commercial aircrafts. Management of interconnections among paper-based operational documents can be a challenge for pilots, especially when time pressure is high in normal, abnormal, and emergency situations. This dissertation is a contribution to the design of an Onboard Context-Sensitive Information System (OCSIS). The claim is that the use of contextual information facilitates access to appropriate operational content at the right time either …

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Economic Feasibility And Increased Sustainability Of Short Span Arch Culvert, Rafsan Jani Rafi Nov 2015

Economic Feasibility And Increased Sustainability Of Short Span Arch Culvert, Rafsan Jani Rafi

Theses and Dissertations

Short span box culverts are widely used for stream flow passing throughout the State of Arkansas. Arkansas State Highway and Transportation Department (AHTD) has standard box culverts ranging from 4 ft to 12 ft in span to use for individual box culvert combination. This study is strictly for culverts with a total span range from 10 ft to 30 ft. To achieve more than 12 ft culvert span, AHTD uses different combinations of standard box culverts. As a result, the clear span becomes smaller and may cause higher debris accumulation near the culvert openings. The goal of this study is …

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Ehawk: Uav - Remote Launch Of Unmanned Aerial Vehicles Kite Based System, Matthew R. Rossett Nov 2015

Ehawk: Uav - Remote Launch Of Unmanned Aerial Vehicles Kite Based System, Matthew R. Rossett

Theses and Dissertations

Unmanned aerial vehicles, also known as UAVs or drones, are becoming favorable assets in multiple fields. Along with this new technology comes new improvements, including the EHAWK: UAV system, a proposed system to increase the range of UAVs by providing an alternate method for launching. The EHAWK: UAV is a kite based system for launching UAVs. The system uses a kite which acts as a sky anchor or fixed point in the sky. A tether is attached from the kite to the ground. A shuttle device then attached to the tether line. That shuttle carries the UAV up the line …

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Aerodynamic Improvement Of The Byu Supermileage Vehicle, Sayan Dobronsky Nov 2015

Aerodynamic Improvement Of The Byu Supermileage Vehicle, Sayan Dobronsky

Theses and Dissertations

The purpose of this thesis work was to design a new shape for the BYU Supermileage vehicle in order to improve its fuel efficiency. Computational Fluid Dynamics (CFD) was used to obtain the coefficient of drag (CD) and drag area of the current baseline vehicle at a Reynolds number of 1.6x10^6 and 8.7x10^5. Then a new shape was developed using mesh morphing software. The new shape was imported into the CFD program and the drag figures and airflow plots from the modified design were compared with the baseline vehicle. Scale models of the vehicles were also printed using a 3D …

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Integrating Process Mining With Discrete-Event Simulation Modeling, Siyao Liu Nov 2015

Integrating Process Mining With Discrete-Event Simulation Modeling, Siyao Liu

Theses and Dissertations

Discrete-event simulation (DES) is an invaluable tool which organizations can use to help better understand, diagnose, and optimize their operational processes. Studies have shown that for the typical DES exercise, the greatest amount of time is spent on developing an accurate model of the process that is to be studied. Process mining, a similar field of study, focuses on using historical data stored in software databases to accurate recreate and analyze business processes. Utilizing process mining techniques to help rapidly develop DES models can drastically reduce the amount of time spent building simulation models, which ultimately will enable organizations to …

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Deriving System Vulnerabilities Using Log Analytics, Matthew Somers Higbee Nov 2015

Deriving System Vulnerabilities Using Log Analytics, Matthew Somers Higbee

Theses and Dissertations

System Administrators use many of the same tactics that are implemented by hackers to validate the security of their systems, such as port scanning and vulnerability scanning. Port scanning is slow, and can be highly inaccurate. After a scan is complete, the results of the scan must be cross checked with a vulnerability database to discover if any vulnerabilities are present. While these techniques are useful, they have severe limitations. System Administrators have full access to all of their machines. They should not have to rely exclusively on port scanning them from the outside of their machines to check for …

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High-Efficiency Passive And Active Phased Arrays And Array Feeds For Satellite Communications, Zhenchao Yang Nov 2015

High-Efficiency Passive And Active Phased Arrays And Array Feeds For Satellite Communications, Zhenchao Yang

Theses and Dissertations

Satellite communication (Satcom) services are used worldwide for voice, data, and video links due to various appealing features. Parabolic reflector antennas are typically used to serve a cost effective scheme for commercial applications. However, mount degradation, roof sag, and orbital decay motivate the need for beam steering. Limited scan range beam steering opens a third option for electronic beam steering with lower cost than full aperture phased arrays and higher tracking speed and accuracy than mechanical-only steering.Multiple high efficiency passive patch array feeds were designed, fabricated, and measured, including a 2x2 MSA array, a stacked shorted annular patch antenna, and …

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A Compact Phased Array Radar For Uas Sense And Avoid, Jonathan Cullinan Spencer Nov 2015

A Compact Phased Array Radar For Uas Sense And Avoid, Jonathan Cullinan Spencer

Theses and Dissertations

As small unmanned aerial systems (UAS) are introduced into the national airspace, measures must be introduced to ensure that they do not interfere with manned aviation and other UAS. Radar provides an attractive solution because of its inherent range accuracy and because it works in diverse weather and lighting conditions. Traditional radar systems, however, are large and high power and do not meet the size, weight and power (SWaP) constraints imposed by UAS, and fully integrated automotive solution do not provide the necessary range. This thesis proposes a compact radar system that meets both the SWaP and range requirements for …

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Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames Nov 2015

Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames

Theses and Dissertations

Minimally Invasive Surgery (MIS) is a growing field including both laparoscopic androbotic operations. Surgeons and engineers are making continual efforts to reduce the negative effects of procedures on patients. Reducing the size of the surgical instruments is one effective method pursued in this effort. When the instruments approach 3 mm in diameter, they reach a threshold where the entry incisions can be small enough that no scar is left on the patient. Laparoscopic instruments on this scale exist but typically lack wrist articulation and only have 1 degree of freedom (DoF). Alternatively, robotic surgical instruments can achieve high levels of …

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Lignin-Derived Thermosetting Vinyl Ester Resins For High Performance Applications, Daniel Rogers Oct 2015

Lignin-Derived Thermosetting Vinyl Ester Resins For High Performance Applications, Daniel Rogers

Theses and Dissertations

Vinyl ester (VE) resins are utilized to produce polymer matrix composites for use in a wide range of applications due to possessing relatively high moduli, strengths, and glass transition temperatures while maintaining low weight and cost. VE resins often contain high concentrations of a petroleum-based reactive diluent (RD), such as styrene. Many of the commonly used RDs have been designated as hazardous air pollutants, potential carcinogens, and volatile organic compounds. Renewable VE resins and RDs with similar performance to petroleum-based RDs are desired to potentially mitigate the aforementioned hazards as well as to facilitate the transition from petrochemical feedstocks to …

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Compose: Compacted Object Sample Extraction A Framework For Semi-Supervised Learning In Nonstationary Environments, Karl Dyer Oct 2015

Compose: Compacted Object Sample Extraction A Framework For Semi-Supervised Learning In Nonstationary Environments, Karl Dyer

Theses and Dissertations

An increasing number of real-world applications are associated with streaming data drawn from drifting and nonstationary distributions. These applications demand new algorithms that can learn and adapt to such changes, also known as concept drift. Proper characterization of such data with existing approaches typically requires substantial amount of labeled instances, which may be difficult, expensive, or even impractical to obtain. In this thesis, compacted object sample extraction (COMPOSE) is introduced - a computational geometry-based framework to learn from nonstationary streaming data - where labels are unavailable (or presented very sporadically) after initialization. The feasibility and performance of the algorithm are …

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Multiple Detector Wireless Fnirs Sensor To Detect Hemodynamic Activity, Sivaram Karra Oct 2015

Multiple Detector Wireless Fnirs Sensor To Detect Hemodynamic Activity, Sivaram Karra

Theses and Dissertations

An established, non-invasive and flexible technique, "functional Near Infra-Red Spectroscopy" (fNIRS), has opened new opportunities for the study of brain functionality. This powerful method uses the optical properties of a tissue at multiple near infra-red wavelengths to dynamically determine the levels of both oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hbr). Traditional techniques such as functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), Electroencephalography (EEG) and Event Related brain Potentials (ERP) have increased our understanding of brain functionality, however, the basic limitations of these technologies such as high cost of equipment, difficulty of operation and levels of radiation make access …

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Using Star-Ccm+ To Evaluate Multi-User Collaboration In Cfd, Kasey Johnson Webster Oct 2015

Using Star-Ccm+ To Evaluate Multi-User Collaboration In Cfd, Kasey Johnson Webster

Theses and Dissertations

The client-server architecture of STAR-CCM+ allows multiple users to collaborate on a simulation set-up. The effectiveness of collaboration with this architecture is tested and evaluated on five models. The testing of these models is a start to finish set-up of an entire simulation excluding computational time for generating mesh and solving the solution. The different models have distinct differences which test every operation that would be used in a general CFD simulation. These tests focus on reducing the time spent preparing the geometry to be meshed, including setting up for a conformal mesh between multiple regions in conjugate heat transfer …

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Design And Validation Of A Complex Loading Whole Spinal Segment Bioreactor, Amanda Marie Beatty Oct 2015

Design And Validation Of A Complex Loading Whole Spinal Segment Bioreactor, Amanda Marie Beatty

Theses and Dissertations

Intervertebral disc (IVD) degeneration is a prevalent health problem that is highly linked to back pain. To understand the disease and tissue response to therapies, ex-vivo whole IVD organ culture systems have recently been introduced. The goal of this study was to develop and validate a whole spinal segment culturing system that loads the disc in complex loading similar to the in-vivo condition, while preserving the adjacent endplates and vertebral bodies. The complex loading applied to the spinal segment was achieved with three pneumatic cylinders. The pneumatic cylinders were rigidly attached to two triangular alumni plates at each corner, comprising …

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Leveraging External Sensor Data For Enhanced Space Situational Awareness, Charlie T. Bellows Sep 2015

Leveraging External Sensor Data For Enhanced Space Situational Awareness, Charlie T. Bellows

Theses and Dissertations

Reliable Space Situational Awareness (SSA) is a recognized requirement in the current congested, contested, and competitive environment of space operations. A shortage of available sensors and reliable data sources are some current limiting factors for maintaining SSA. Unfortunately, cost constraints prohibit drastically increasing the sensor inventory. Alternative methods are sought to enhance current SSA, including utilizing non-traditional data sources (external sensors) to perform basic SSA catalog maintenance functions. Astronomical data, for example, routinely collects serendipitous satellite streaks in the course of observing deep space; but tactics, techniques, and procedures designed to glean useful information from those collects have yet to …

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Modular Heat Dissipation Technique For A Cubesat, Melih Eken Sep 2015

Modular Heat Dissipation Technique For A Cubesat, Melih Eken

Theses and Dissertations

In recent years, due to their many advantages, interest in larger scale CubeSats, such as 3U and 6U, has been increased. Correspondingly, dissipating the heat from the heat generating components in the CubeSat has become a challenge for thermal control. In this research, a modular approach was developed to dissipate heat from the overheating components in a CubeSat. To accomplish this, both experimental and computational methodologies were used. A 6U CubeSat was computationally modeled and the model correlated by experimental test results. Subsequently, validated CubeSat thermal model was used to design a modular heat dissipater. Validation and performance experiments of …

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Analysis Of Hypersonic Vehicle Wakes, Matthew A. Kania Sep 2015

Analysis Of Hypersonic Vehicle Wakes, Matthew A. Kania

Theses and Dissertations

As advancements are made with ballistic missiles, particularly in the area of hypersonic bodies, there is a growing need to advance the methods of detecting these new ballistic weapons. As a result, the National Air and Space Intelligence Center has asked the Air Force Institute of Technology to examine the wake region behind hypersonic bodies. A thorough understanding of the aerothermal phenomena and the chemical reactions occurring in the wake region will enable an advancement of tracking hypersonic bodies. This research examined the wake region behind a hypersonic body using computational fluid dynamics.
This study used Pointwise® to develop a …

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System Architecture Of Small Unmanned Aerial System For Flight Beyond Visual Line-Of-Sight, Kwee Siam Seah Sep 2015

System Architecture Of Small Unmanned Aerial System For Flight Beyond Visual Line-Of-Sight, Kwee Siam Seah

Theses and Dissertations

Small Unmanned Aerial Systems (UAS) have increasingly been used in military application. The application in expanding scope of operations has pushed existing small UAS beyond its designed capabilities. This resulted in frequent modifications or new designs. A common requirement in modification or new design of small UAS is to operate beyond visual Line-Of-Sight (LOS) of the ground pilot. Conventional military development for small UAS adopts a design and built approach. Modification of small Remote Control (RC) aircraft, using Commercial-Off-The Shelf (COTS) equipment, offers a more economical alternative with the prospect of shorter development time compared to conventional approach. This research …

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