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2013

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Articles 4081 - 4110 of 7292

Full-Text Articles in Engineering

Constitutive Parameter Measurement Using Double Ridge Waveguide, Nathan J. Lehman Mar 2013

Constitutive Parameter Measurement Using Double Ridge Waveguide, Nathan J. Lehman

Theses and Dissertations

Electromagnetic materials characterization is important in the design of systems that interact with electromagnetic waves. Determining the constitutive parameters of a material is a vast area of research and practice. For this paper, discussion will focus on a destructive method using waveguides in the frequency range of 6-18 GHz. Traditional methods to perform similar measurements include using coaxial cable, stripline, focus beam and rectangular waveguides. This work will use Double Ridged Waveguide (DRWG) to compare to these other methods and will discuss the attributes and drawbacks of this new approach. The most similar method utilizes rectangular waveguide, so the primary …

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An Architecture For Coexistence With Multiple Users In Frequency Hopping Cognitive Radio Networks, Ryan K. Mclean Mar 2013

An Architecture For Coexistence With Multiple Users In Frequency Hopping Cognitive Radio Networks, Ryan K. Mclean

Theses and Dissertations

The radio frequency (RF) spectrum is a limited resource. Spectrum allotment disputes stem from this scarcity as many radio devices are con confined to a fixed frequency or frequency sequence. One alternative is to incorporate cognition within a configurable radio platform, therefore enabling the radio to adapt to dynamic RF spectrum environments. In this way, the radio is able to actively observe the RF spectrum, orient itself to the current RF environment, decide on a mode of operation, and act accordingly, thereby sharing the spectrum and operating in more flexible manner. This research presents a novel framework for incorporating several …

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Spectral Detection Of Acute Mental Stress With Vis-Swir Hyperspectral Imagery, Elizabeth K. Norvell Mar 2013

Spectral Detection Of Acute Mental Stress With Vis-Swir Hyperspectral Imagery, Elizabeth K. Norvell

Theses and Dissertations

The ability to identify a stressed person is becoming an important aspect across different work environments. Especially in higher-stress career fields, such as first responders and air traffic controllers, mental stress can inhibit a person's ability to accomplish their job. A person's efficiency and psychological state in the work environment can be impeded due to poor mental health. Stress can result in harmful effects on the body, both physically and mentally, including depression, lack of sleep, and fatigue, which can lead to reduced work productivity. Research is being conducted to detect stress in workload-intensive environments. This thesis implements an imaging …

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Metamaterial Structure Design Optimization: A Study Of The Cylindrical Cloak, Jason V. Paul Mar 2013

Metamaterial Structure Design Optimization: A Study Of The Cylindrical Cloak, Jason V. Paul

Theses and Dissertations

Previously, Transformational Optics (TO) has been used as a foundation for designing cylindrical cloaks. The TO method uses a coordinate transform to dictate an anisotropic material parameter gradient in a cylinder coating that guides waves around the cylinder to reduce the Radar Cross Section (RCS). The problem is that the material parameters required for the TO cloak are not physically realizable and thus must be approximated. This problem is compounded by the fact that any approximation deviates from the ideal design and will allow fields to penetrate the cloak layer and interact with the object to be cloaked. Since the …

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Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam Mar 2013

Atmospheric Impact On Long Pulse Laser Detection And Ranging (Ladar) Systems, Isaac B. Putnam

Theses and Dissertations

For conventional imaging systems, GEO space objects cannot be resolved due to their 40 Mm distance. There exists a strong need to obtain high resolution images of GEO objects and to accomplish this task, investigation into the suitability of ISAL is currently underway. A critical component in determining this suitability is to accurately model the atmospheric impacts on LADAR pulses. Conventional knowledge says that while the atmosphere churns, wind is the predominant cause of temporal evolution which simplifies all modeling and simulation into the frozen flow hypothesis. The concern is that the frozen flow hypothesis based phase screen generation techniques …

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Inertial Navigation System Aiding Using Vision, James O. Quarmyne Mar 2013

Inertial Navigation System Aiding Using Vision, James O. Quarmyne

Theses and Dissertations

The aiding of an INS using measurements over time of the line of sight of ground features as they come into view of an onboard camera is investigated. The objective is to quantify the reduction in the navigation states' errors by using bearings-only measurements over time of terrain features in the aircraft's field of view. INS aiding is achieved through the use of a Kalman Filter. The design of the Kalman Filter is presented and it is shown that during a long range, wings level cruising flight at constant velocity and altitude, a 90% reduction in the aided INS-calculated navigation …

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A Multi Agent System For Flow-Based Intrusion Detection, David A . Ryan Mar 2013

A Multi Agent System For Flow-Based Intrusion Detection, David A . Ryan

Theses and Dissertations

The detection and elimination of threats to cyber security is essential for system functionality, protection of valuable information, and preventing costly destruction of assets. This thesis presents a Mobile Multi-Agent Flow-Based IDS called MFIREv3 that provides network anomaly detection of intrusions and automated defense. This version of the MFIRE system includes the development and testing of a Multi-Objective Evolutionary Algorithm (MOEA) for feature selection that provides agents with the optimal set of features for classifying the state of the network. Feature selection provides separable data points for the selected attacks: Worm, Distributed Denial of Service, Man-in-the-Middle, Scan, and Trojan. This …

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Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer Mar 2013

Material Characterization Using Passive Multispectral Polarimetric Imagery, Melissa A . Sawyer

Theses and Dissertations

A new method for characterization of unknown targets using passive multispectral polarimetric imagery is presented. Previous work makes use of a pBRDF derived equation for the degree of linear polarization and with the aid of measurements at multiple incident angles estimates refractive index and reflection angle. This work uses known incident and reflection angles along with dispersion equations and polarimetric data at multiple wavelengths to recover the index of refraction. Although imagery is collected with a division of time polarimeter and a spectral filter wheel in iterative, manual steps, the new algorithm could be applied to any set of registered …

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Airborne Network Data Availability Using Peer To Peer Database Replication On A Distributed Hash Table, Trevor J. Vranicar Mar 2013

Airborne Network Data Availability Using Peer To Peer Database Replication On A Distributed Hash Table, Trevor J. Vranicar

Theses and Dissertations

The concept of distributing one complex task to several smaller, simpler Unmanned Aerial Vehicles (UAVs) as opposed to one complex UAV is the way of the future for a vast number of surveillance and data collection tasks. One objective for this type of application is to be able to maintain an operational picture of the overall environment. Due to high bandwidth costs, centralizing all data may not be possible, necessitating a distributed storage system such as mobile Distributed Hash Table (DHT). A difficulty with this maintenance is that for an Airborne Network (AN), nodes are vehicles and travel at high …

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Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler Mar 2013

Novel Test Fixture For Characterizing Microcontacts: Performance And Reliability, Benjamin F. Toler

Theses and Dissertations

Engineers have attempted to improve reliability and lifecycle performance using novel micro-contact metals, unique mechanical designs and packaging. Contact resistance can evolve over the lifetime of the micro-switch by increasing until failure. This work shows the fabrication of micro-contact support structures and test fixture which allow for micro-contact testing, with an emphasis on the fixture's design to allow the determination and analysis of the appropriate failure mode. The other effort of this investigation is the development of a micro-contact test fixture which can measure contact force and resistance directly and perform initial micro-contact characterization, and two forms of lifecycle testing …

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Network Intrusion Dataset Assessment, David J. Weller-Fahy Mar 2013

Network Intrusion Dataset Assessment, David J. Weller-Fahy

Theses and Dissertations

Research into classification using Anomaly Detection (AD) within the field of Network Intrusion Detection (NID), or Network Intrusion Anomaly Detection (NIAD), is common, but operational use of the classifiers discovered by research is not. One reason for the lack of operational use is most published testing of AD methods uses artificial datasets: making it difficult to determine how well published results apply to other datasets and the networks they represent. This research develops a method to predict the accuracy of an AD-based classifier when applied to a new dataset, based on the difference between an already classified dataset and the …

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Vehicle Minimization For The Multimodal Pickup And Delivery Problem With Time Windows, Benjamin A . Clapp Mar 2013

Vehicle Minimization For The Multimodal Pickup And Delivery Problem With Time Windows, Benjamin A . Clapp

Theses and Dissertations

The algorithm proposed here is used for heuristic solutions for the Multimodal Multiple Vehicle Routing Problem with Unloading Capacity, Pickup and Dropoff, and Time Windows, solved so as to minimize the number of vehicles used, subject to varying objective function values for each vehicle. The MVRP is simplified and split into a routing problem and a scheduling problem. The routing problem is addressed by Dijkstra's Algorithm. This generates a new network for the second stage of the algorithm. It is assumed that the shortest path is the correct path to use, and shipments each travel unimodally. The scheduling problem is …

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A Mixed Integer Programming Model For Improving Theater Distribution Force Flow Analysis, Micah J. Hafich Mar 2013

A Mixed Integer Programming Model For Improving Theater Distribution Force Flow Analysis, Micah J. Hafich

Theses and Dissertations

Obtaining insight into potential vehicle mixtures that will support theater distribution, the final leg of military distribution, can be a challenging and time consuming process for United States Transportation Command (USTRANSCOM) force flow analysts. The current process of testing numerous different vehicle mixtures until separate simulation tools demonstrate feasibility is iterative and overly burdensome. Improving on existing research, a mixed integer programming model was developed to allocate specific vehicle types to delivery items, or requirements, in a manner that would minimize both operational costs and late deliveries. This gives insight into the types and amounts of vehicles necessary for feasible …

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Aerial Refueling Simulator Validation Using Operational Experimentation And Response Surface Methods With Time Series Responses, Alexander P. Hillman Mar 2013

Aerial Refueling Simulator Validation Using Operational Experimentation And Response Surface Methods With Time Series Responses, Alexander P. Hillman

Theses and Dissertations

An important program in the Department of Defense is the KC-46 Supertanker. Dubbed the future of the Air Force's aerial refueling inventory, the KC-46 will replace dozens of ailing previous generation tanker aircraft. The Aerial Refueling Airplane Simulator Qualification document governs the methods by which Air Mobility Command validates its simulators, some of which will be KC-46 simulators in the near future. The methodology set forward in this thesis utilizes historical data of aircraft performance from similar air frames to gain statistical insight into the performance design space of the KC-46. Leveraging this insight, the methodology provides through a framework …

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Control Variates And Optimal Designs In Metamodeling, Joshua B. Meents Mar 2013

Control Variates And Optimal Designs In Metamodeling, Joshua B. Meents

Theses and Dissertations

At the heart of most modeling issues is a focus on variance reduction. Experimental designs are chosen based on both efficiency and a variety of variance based criteria. In many situations due to cost, time and availability issues it is beneficial to produce metamodels of simulations. Experimental designs for the region of operability are constructed to collect the simulation output required to construct representative metamodels. Independently, the method of control variates is a well established technique often employed to reduce variance in discrete event simulations. This thesis explores the variance reduction benefits that can be obtained by combining optimal experimental …

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Evaluating Courses Of Actions At The Strategic Planning Level, Alhmet Ozdemir Mar 2013

Evaluating Courses Of Actions At The Strategic Planning Level, Alhmet Ozdemir

Theses and Dissertations

Like almost all real life problems, Strategic planning is a good example of a problem with more than one objective. One of the most important steps of strategic planning is to generate and evaluate the courses of actions (COA) which can fulfill the mission and vision of the organization. This is a critical process since it is impractical to start the executed COA over. In this research, value-focused thinking (VFT) is used as a decision analysis tool to assess COAs. A general model is created to select the best COA for strategic planning such as air force operation planning. To …

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Modeling The Impact Of The Payload Alert Communications System (Pacs) On The Accuracy Of Conjunction Analysis, Landon B. Bastow Mar 2013

Modeling The Impact Of The Payload Alert Communications System (Pacs) On The Accuracy Of Conjunction Analysis, Landon B. Bastow

Theses and Dissertations

The Air Force Institute of Technology (AFIT) and the Air Force Research Laboratory (AFRL) are jointly developing a system known as the Payload Alert Communications System (PACS) whose purpose is to decrease the statistical uncertainty in the location of resident space objects (RSOs). PACS is designed to augment the Joint Space Operations Center's (JSpOC) existing space object tracking capabilities which is expected to increase the accuracy of conjunction estimation. In the current PACS design, a small payload would be attached to certain RSOs prior their launch. It is envisioned that this payload would basically consist of a microcontroller, a Global …

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Fist And The Analytical Hierarchy Process: Comparative Modeling, Trevor A . Gustafson Mar 2013

Fist And The Analytical Hierarchy Process: Comparative Modeling, Trevor A . Gustafson

Theses and Dissertations

FIST is an emerging and unproven rapid acquisition model that stands for Fast, Inexpensive, Simple, and Tiny. The purpose of this research is to develop an Analytical Hierarchy Process (AHP) model based on the FIST concepts, to be applied as a comparative tool against the FIST model. The results indicate that the FIST model is reproducible with the AHP theory and that there are certain program characteristics that denote if a program would benefit from being developed by FIST. However, there are distinct weaknesses to the model that signify not all programs would succeed if FIST was employed during development. …

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Understanding The Effects Of Climate On Airfield Pavement Deterioration Rates, Justin C. Meihaus Mar 2013

Understanding The Effects Of Climate On Airfield Pavement Deterioration Rates, Justin C. Meihaus

Theses and Dissertations

Over the past two decades, pavement engineers at the Air Force Civil Engineer Center have noticed the majority of identified distresses from PCI airfield surveys are climate related. To verify these trends, a comprehensive analysis of the current airfield pavement distress database was accomplished based on a climate region perspective. A four-zone regional climatic model was created for the United States using geospatial interpolation techniques and climate data acquired from WeatherBank Inc. Once the climatic regional model was developed, the climate information for each installation was imported into the Air Force pavement distress database within PAVER. Utilizing the pavement condition …

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Assessment Of Potential Carbon Dioxide-Based Demand Control Ventilation System Performance In Single Zone Systems, Joseph G. Pickenpaugh Mar 2013

Assessment Of Potential Carbon Dioxide-Based Demand Control Ventilation System Performance In Single Zone Systems, Joseph G. Pickenpaugh

Theses and Dissertations

Heating, ventilation, and air conditioning (HVAC) use accounts for 43% of commercial energy consumption, with close to 5% used for ventilation purposes. Federal government agencies face both energy consumption reduction mandates and reduced funding. Carbon dioxide (CO2) based demand control ventilation (DCV) is a technology that allows for reduced energy consumption by allowing facility designers to introduce outside air based on facility occupancy, per American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) standards. This research aims to create a generalized methodology assessing energy and cost reductions from CO2-based DCV and then apply it to a specific facility at …

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Effects Of Stereoscopic 3d Digital Radar Displays On Air Traffic Controller Performance, Jason G. Russi Mar 2013

Effects Of Stereoscopic 3d Digital Radar Displays On Air Traffic Controller Performance, Jason G. Russi

Theses and Dissertations

Air traffic controllers are responsible for directing air traffic based upon decisions made from traffic activity depicted on 2Dimensional (2D) radar displays. Controllers must identify aircraft and detect potential conflicts while simultaneously developing and executing plans of action to ensure safe separation is maintained. With a nearly 100% increase in traffic expected within the next decade (FAA, 2012a), controllers' abilities to rapidly interpret spacing and maintain awareness for longer durations with increased workload will become increasingly imperative to safety. The current display design spatially depicts an aircraft's position relative to the controller's airspace as well as speed, altitude, and direction …

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Applying Hyperspectral Imaging To Heart Rate Estimation For Adaptive Automation, Joshua M. Splawn Mar 2013

Applying Hyperspectral Imaging To Heart Rate Estimation For Adaptive Automation, Joshua M. Splawn

Theses and Dissertations

Automation use continues to increase in Air Force systems with the goal of improving operator efficiency and effectiveness. Unfortunately, systems are often complex, potentially imposing increased mental task load on the operator, or placing the operator in a supervisory role where they can become dependent on automation. Adaptive automation is a proposed solution, where automation is triggered when an operator is overloaded, and disabled as the operator is underloaded. Changes in physiological measures have shown promise in triggering automation. Unfortunately heart rate measurement can be obtrusive and impractical in day-to-day operations. This research used the Air Force Multi-Attribute Task Battery …

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Investigations Of Partially Immersed Spinning Spheres In A Liquid Bath And Butterfly Flight, Kenneth Roy Langley Mar 2013

Investigations Of Partially Immersed Spinning Spheres In A Liquid Bath And Butterfly Flight, Kenneth Roy Langley

Theses and Dissertations

This thesis examines two important problems in fluid dynamics: that of a partially immersed sphere spinning in a bath of liquid and the measurement of flow velocities around a free flying butterfly. Although the actual problems are quite different, each problem incorporates many of the same principles and techniques. When a hard-boiled egg spins through a pool of milk on the kitchen counter, the milk rises up the sides of the egg and droplets are ejected. This phenomenon occurs when any partially submerged object whose radius increases upward from the fluid surface (e.g., spheres, inverted cones, rings, etc.), spins in …

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3d Digital Image Processing For Biofilm Quantification From Confocal Laser Scanning Microscopy, Jerzy S. Zielinski Mar 2013

3d Digital Image Processing For Biofilm Quantification From Confocal Laser Scanning Microscopy, Jerzy S. Zielinski

Theses and Dissertations

The dramatic increase in number and volume of digital images produced in medical diagnostics, and the escalating demand for rapid access to these relevant medical data, along with the need for interpretation and retrieval has become of paramount importance to a modern healthcare system. Therefore, there is an ever growing need for processed, interpreted and saved images of various types. Due to the high cost and unreliability of human-dependent image analysis, it is necessary to develop an automated method for feature extraction, using sophisticated mathematical algorithms and reasoning. This work is focused on digital image signal processing of biological and …

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Hydrogen Storage Properties Of Magnesium Based Nanostructured Materials Produced By Glancing Angle Deposition, Mehmet Fatih Cansizoglu Mar 2013

Hydrogen Storage Properties Of Magnesium Based Nanostructured Materials Produced By Glancing Angle Deposition, Mehmet Fatih Cansizoglu

Theses and Dissertations

Hydrogen is proposed as an ideal fuel for future global energy requirements with the potential to reduce carbon dioxide and other greenhouse gas emissions and improve energy independence for countries. Hydrogen is ideal for mobile applications, such as transportation vehicles and mobile devices. However storage of hydrogen remains as a challenge to realize this transition. One of the promising approaches in solid state storage is storing hydrogen in the form of metal hydrides. High hydrogen storage capacity of 7.6 wt% (weight percentage), reversibility, low cost, and abundance make magnesium an attractive material for solid state hydrogen storage. The main drawbacks …

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Application Of Fuel Element Combustion Properties To A Semi-Empirical Flame Propagation Model For Live Wildland Utah Shrubs, Chen Shen Mar 2013

Application Of Fuel Element Combustion Properties To A Semi-Empirical Flame Propagation Model For Live Wildland Utah Shrubs, Chen Shen

Theses and Dissertations

Current field models for wildfire prediction are mostly based on dry or low-moisture fuel combustion research. To better study live fuel combustion behavior and develop the current semi-empirical bush combustion model, a laminar flow flat-flame burner was used to provide a convection heating source to ignite individual live fuel samples. In this research project, four Utah species were studied: Gambel oak (Quercus gambelii), canyon maple (Acer grandidentatum), big sagebrush (Artemisia tridentata) and Utah juniper (Juniperus osteosperma). Leaf geometrical parameters and time-dependent combustion behavior were recorded. Qualitative results included various combustion phenomena like bursting, brand formation and bending. Quantitative results included …

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Ralph A. O'Neill, Arizona's Other Ww I Ace, Alan Roesler Mar 2013

Ralph A. O'Neill, Arizona's Other Ww I Ace, Alan Roesler

ERAU Prescott Aviation History Program

Hear the fascinating story of Ralph O'Neill, who was inducted into the Arizona Aviation Hall of Fame in 2012. He flew 103 combat missions with the 147th Aero Squadron (a squadron mate of Ernest Love of Prescott); started a functional Mexican Air Force in the 1920s and the New York Rio & Buenos Aires Airline in 1929, which later merged with Pan Am.

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Microfabrication Processes And Advancements In Planar Electrode Ion Traps As Mass Spectrometers, Brett Jacob Hansen Mar 2013

Microfabrication Processes And Advancements In Planar Electrode Ion Traps As Mass Spectrometers, Brett Jacob Hansen

Theses and Dissertations

This dissertation presents advances in the development of planar electrode ion traps. An ion trap is a device that can be used in mass analysis applications. Electrode surfaces create an electric field profile that trap ionized molecules of an analyte. The electric fields can then be manipulated to mass-selectively eject ions out of the trap into a detector. The resulting data can be used to analyze molecular structure and composition of an unknown compound. Conventional ion traps require machined electrode surfaces to form the electric trapping field. This class of electrode presents significant obstacles when attempting to miniaturize ion traps …

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A Trophic State Analysis Of Lakes In Yellowstone National Park, Anthony Alexander Melcher Mar 2013

A Trophic State Analysis Of Lakes In Yellowstone National Park, Anthony Alexander Melcher

Theses and Dissertations

Eutrophication is of interest in the field of water quality. Eutrophic lakes, when used as sources for drinking water, can cause problems during the treatment process, for example algae blooms can clog filters, requiring more water and energy to be used during the cleaning and backwashing of the filters. Excess nutrient loading and eutrophication can also harm fish and aquatic life habitats. Certain species of algae and cyanobacteria can be toxic to humans as well. Since 1998, Dr. A. Woodruff Miller has collected water samples from 46 lakes and ponds in Yellowstone National Park. The Carlson Trophic State Index, the …

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Passive Stiffness Of Coupled Wrist And Forearm Rotations, Will Brandon Drake Mar 2013

Passive Stiffness Of Coupled Wrist And Forearm Rotations, Will Brandon Drake

Theses and Dissertations

The dynamics of wrist rotations are dominated by joint stiffness, which the neuromuscular system must account and compensate for when controlling wrist movements. Because wrist stiffness is anisotropic, movements in some directions require less torque than movements in others, creating opportunities to follow "paths of least resistance." Forearm pronation-supination (PS) can combine with wrist flexion-extension (FE) and radial-ulnar deviation (RUD) to allow the wrist to rotate in directions of least stiffness. Evaluating this hypothesis, and understanding the control of combined wrist and forearm rotations in general, requires a knowledge of the stiffness (the dominant mechanical impedance) encountered during combined wrist …

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