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2016

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Articles 7891 - 7920 of 9604

Full-Text Articles in Engineering

Nanoengineered Energy Harvesting And Storage Devices, Chao Li Jan 2016

Nanoengineered Energy Harvesting And Storage Devices, Chao Li

Electronic Theses and Dissertations

Organic and perovskite solar cells have recently attracted significant attention due to its flexibility, ease of fabrication and excellent performance. In order to realize even better performance for organic and perovskite solar cells, rejuvenated effort towards developing nanostructured electrodes and high quality active layer is necessary. In this dissertation, several strategic directions of enhancing the performance of organic and perovskite solar cells are investigated. An introduction and background of organic and perovskite solar cells, which includes motivation, classification and working principles, nanostructured electrode materials and solvent effect on active materials, and devices fabrication, are presented. A facile method, called Spin-on …

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Design Of Surface Chemical Reactivity And Optical Properties In Glasses, Antoine Lepicard Jan 2016

Design Of Surface Chemical Reactivity And Optical Properties In Glasses, Antoine Lepicard

Electronic Theses and Dissertations

Thermal poling is a technique which involves the application of a strong DC electric field to a glass substrate heated below its glass transition temperature (Tg). Following the treatment, a static electric field is frozen inside the glass matrix, effectively breaking its centrosymmetry. Historically, this treatment has been used as a way to gain access to second order non-linear optical properties in glasses. However, recent efforts have shown that the treatment was responsible for structural changes as well as surface property modifications. Our study was focused on using this technique to tailor surface properties in oxide (borosilicate and niobium borophosphate) …

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Stochastic-Based Computing With Emerging Spin-Based Device Technologies, Yu Bai Jan 2016

Stochastic-Based Computing With Emerging Spin-Based Device Technologies, Yu Bai

Electronic Theses and Dissertations

In this dissertation, analog and emerging device physics is explored to provide a technology platform to design new bio-inspired system and novel architecture. With CMOS approaching the nano-scaling, their physics limits in feature size. Therefore, their physical device characteristics will pose severe challenges to constructing robust digital circuitry. Unlike transistor defects due to fabrication imperfection, quantum-related switching uncertainties will seriously increase their susceptibility to noise, thus rendering the traditional thinking and logic design techniques inadequate. Therefore, the trend of current research objectives is to create a non-Boolean high-level computational model and map it directly to the unique operational properties of …

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A Contextual Approach To Real Time, Interactive Narrative Generation, James Hollister Jan 2016

A Contextual Approach To Real Time, Interactive Narrative Generation, James Hollister

Electronic Theses and Dissertations

Oral story telling has become a lost art of family histories because social media and technology have taken over the personal interactions that once passed on the important stories and facts from generation to generation. This dissertation presents and evaluates a method of generating a narrative with input from the listener without actually forcing him or her to become an actual character in the narrative. This system is called CAMPFIRE Story Telling System (STS) and employs a contextual approach to story generation. This system uses the Cooperating Context Method (CCM) to generate and tell dynamic stories in real time and …

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Modeling Wastewater Indicators And Effects Of Contaminant Removal Strategies On Groundwater And Spring Discharge In A Karst Aquifer, Erin Reed Jan 2016

Modeling Wastewater Indicators And Effects Of Contaminant Removal Strategies On Groundwater And Spring Discharge In A Karst Aquifer, Erin Reed

Electronic Theses and Dissertations

This dissertation reports on research related to groundwater and contaminant transport to the Volusia Blue Spring (VBS), an Outstanding Florida Water Body located in Volusia County (Florida). The integration of springshed water quality and contaminant fate and transport (CFT) modeling played key roles in the evaluation of anthropogenic recharge impacts on VBS. To study anthropogenic recharge into the karst limestone aquifer, wastewater effluent, golf course ponds, septic tanks, groundwater monitoring wells, and VBS discharge were sampled for boron, nitrate-nitrogen, nitrate-oxygen and their isotopes spatially throughout the VBS springshed. Data related to natural water features, rainfall, land use, water use, treated …

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Microscopic Safety Evaluation And Prediction For Special Expressway Facilities, Ling Wang Jan 2016

Microscopic Safety Evaluation And Prediction For Special Expressway Facilities, Ling Wang

Electronic Theses and Dissertations

Expressways are of great importance and serve as the backbone of a roadway system. One of the reasons why expressways increase travel speeds and provide high level of services is that limited access is provided to permit vehicles to enter or exit expressways. Entering and exiting of vehicles are accomplished through interchanges, which consist of several ramps, thus the spacing between ramps is important. A weaving segment might form when an on-ramp is closely followed by an off-ramp. The geometric design of ramps and the traffic behavior of weaving segments are different from other expressway segments. These differences result in …

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Electrical Properties Of Polymer-Derived Silicoaluminum Carboxide Ceramics (Sialco) And Their Applications In Micro-Sensors, Yejie Cao Jan 2016

Electrical Properties Of Polymer-Derived Silicoaluminum Carboxide Ceramics (Sialco) And Their Applications In Micro-Sensors, Yejie Cao

Electronic Theses and Dissertations

Polymer-derived ceramic (PDC) is a new kind of material which is directly synthesized by the thermal decomposition of polymer precursors. Due to their unique structure, which consists of the amorphous matrix phase and free-carbon phase, PDCs exhibit many distinguished properties even at high-temperature environment such as oxidation and creep resistance, amorphous semiconducting behavior as well as piezoresistive behavior. These outstanding properties make PDCs become promising candidates for various applications especially for high-temperature microsensors. However, most common used PDCs in the market now are SiC, SiCN and Si(M)CN ceramics, the high price and toxicity of their raw materials as well as …

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Content-Based Information Retrieval Via Nearest Neighbor Search, Yinjie Huang Jan 2016

Content-Based Information Retrieval Via Nearest Neighbor Search, Yinjie Huang

Electronic Theses and Dissertations

Content-based information retrieval (CBIR) has attracted significant interest in the past few years. When given a search query, the search engine will compare the query with all the stored information in the database through nearest neighbor search. Finally, the system will return the most similar items. We contribute to the CBIR research the following: firstly, Distance Metric Learning (DML) is studied to improve retrieval accuracy of nearest neighbor search. Additionally, Hash Function Learning (HFL) is considered to accelerate the retrieval process. On one hand, a new local metric learning framework is proposed - Reduced-Rank Local Metric Learning (R2LML). By considering …

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Work Function Extraction Of Indium Tin Oxide Used As Transparent Gate Electrode For Mosfet., Shraddha Nehate Jan 2016

Work Function Extraction Of Indium Tin Oxide Used As Transparent Gate Electrode For Mosfet., Shraddha Nehate

Electronic Theses and Dissertations

Recent commercialization has peaked interest in transparent conducting oxides being implemented in display technology. Indium Tin Oxide (ITO) is a popular transparent conducting oxide which has been utilized as high work function electrode in liquid crystal displays, solar cells, gas sensors and heat reflecting films. Indium Tin Oxide films exhibit excellent transmission characteristics in the visible and infrared spectrum while maintaining high electrical conductivity. High work function electrodes are used to inject holes into organic materials. In majority applications the ITO work function has an impact on the device performance as it affects the energy barrier height at the hetero-junction …

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Enhanced Hardware Security Using Charge-Based Emerging Device Technology, Yu Bi Jan 2016

Enhanced Hardware Security Using Charge-Based Emerging Device Technology, Yu Bi

Electronic Theses and Dissertations

The emergence of hardware Trojans has largely reshaped the traditional view that the hardware layer can be blindly trusted. Hardware Trojans, which are often in the form of maliciously inserted circuitry, may impact the original design by data leakage or circuit malfunction. Hardware counterfeiting and IP piracy are another two serious issues costing the US economy more than $200 billion annually. A large amount of research and experimentation has been carried out on the design of these primitives based on the currently prevailing CMOS technology. However, the security provided by these primitives comes at the cost of large overheads mostly …

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Developing New Power Management And High-Reliability Schemes In Data-Intensive Environment, Ruijun Wang Jan 2016

Developing New Power Management And High-Reliability Schemes In Data-Intensive Environment, Ruijun Wang

Electronic Theses and Dissertations

With the increasing popularity of data-intensive applications as well as the large-scale computing and storage systems, current data centers and supercomputers are often dealing with extremely large data-sets. To store and process this huge amount of data reliably and energy-efficiently, three major challenges should be taken into consideration for the system designers. Firstly, power conservation–Multicore processors or CMPs have become a mainstream in the current processor market because of the tremendous improvement in transistor density and the advancement in semiconductor technology. However, the increasing number of transistors on a single die or chip reveals a super-linear growth in power consumption …

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Compressive And Coded Change Detection: Theory And Application To Structural Health Monitoring, Omid Sarayanibafghi Jan 2016

Compressive And Coded Change Detection: Theory And Application To Structural Health Monitoring, Omid Sarayanibafghi

Electronic Theses and Dissertations

In traditional sparse recovery problems, the goal is to identify the support of compressible signals using a small number of measurements. In contrast, in this thesis the problem of identification of a sparse number of statistical changes in stochastic phenomena is considered when decision makers only have access to compressed measurements, i.e., each measurement is derived by a subset of features. Herein, we propose a new framework that is termed Compressed Change Detection. The main approach relies on integrating ideas from the theory of identifying codes with change point detection in sequential analysis. If the stochastic properties of certain features …

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Evaluating Wrong-Way Driving For Florida Interstates And Toll Road Facilities: A Risk-Based Investigation, And Countermeasure Development, John Rogers Jan 2016

Evaluating Wrong-Way Driving For Florida Interstates And Toll Road Facilities: A Risk-Based Investigation, And Countermeasure Development, John Rogers

Electronic Theses and Dissertations

The focus of this dissertation was to examine wrong-way driving (WWD) events on Florida toll roads and Interstates. The universe of WWD data contains many sources of WWD events or incidents. Most of the previous research focused only on WWD crashes without considering other data such as WWD citations and 911 calls related to WWD incidents. While WWD citations and 911 calls data is abundant, this data has been largely overlooked in other studies. This dissertation provides a novel and holistic approach for evaluating WWD risk, which considers other risk factors such as WWD citations and 911 calls in addition …

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Evaluation Of Crash Modification Factors And Functions Including Time Trends At Intersections, Jung-Han Wang Jan 2016

Evaluation Of Crash Modification Factors And Functions Including Time Trends At Intersections, Jung-Han Wang

Electronic Theses and Dissertations

Traffic demand has increased as population increased. The US population reached 313,914,040 in 2012 (US Census Bureau, 2015). Increased travel demand may have potential impact on roadway safety and the operational characteristics of roadways. Total crashes and injury crashes at intersections accounted for 40% and 44% of traffic crashes, respectively, on US roadways in 2007 according to the Intersection Safety Issue Brief (FHWA, 2009). Traffic researchers and engineers have developed a quantitative measure of the safety effectiveness of treatments in the form of crash modification factors (CMF). Based on CMFs from multiple studies, the Highway Safety Manual (HSM) Part D …

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Synthesis And Characterization Of Stable And Metastable Phases In Ni- And Fe-Based Alloy Systems By Mechanical Alloying, Ahmed Al-Joubori Jan 2016

Synthesis And Characterization Of Stable And Metastable Phases In Ni- And Fe-Based Alloy Systems By Mechanical Alloying, Ahmed Al-Joubori

Electronic Theses and Dissertations

Mechanical Alloying (MA) is a process that involves repeated cold welding, fracturing and rewelding of powder particles in a high-energy ball mill and has been used extensively to synthesize both stable (equilibrium) and metastable phases in a number of alloy systems. This is due to its ability to achieve many effects simultaneously, viz., reduction in grain size, introduction of a variety of crystal defects, disordering of the lattice, and modifying the crystal structures of materials; all these allowing alloying and phase transformations to occur in powders. In this Dissertation, we have synthesized a number of different alloy phases in Ni- …

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Investigation Of Infrared Thermography For Subsurface Damage Detection Of Concrete Structures, Shuhei Hiasa Jan 2016

Investigation Of Infrared Thermography For Subsurface Damage Detection Of Concrete Structures, Shuhei Hiasa

Electronic Theses and Dissertations

Deterioration of road infrastructure arises from aging and various other factors. Consequently, inspection and maintenance have been a serious worldwide problem. In the United States, degradation of concrete bridge decks is a widespread problem among several bridge components. In order to prevent the impending degradation of bridges, periodic inspection and proper maintenance are indispensable. However, the transportation system faces unprecedented challenges because the number of aging bridges is increasing under limited resources, both in terms of budget and personnel. Therefore, innovative technologies and processes that enable bridge owners to inspect and evaluate bridge conditions more effectively and efficiently with less …

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A Study Of Crystallization Behavior In Phase Separated Chalcogenide Glasses, Andrew Buff Jan 2016

A Study Of Crystallization Behavior In Phase Separated Chalcogenide Glasses, Andrew Buff

Electronic Theses and Dissertations

Chalcogenide glasses (ChG) are known for their wide transmission ranges in the infrared and for their high refractive indices. However, applications for ChG are often limited by their poor thermal/mechanical properties. Precipitating a secondary crystalline phase in the glass matrix can improve these properties, but too much crystallization and/or large or multiple phase crystallites can lead to a loss in infrared (IR) transmission. Controlled crystallization can be used to tune the properties of these glasses. This work examines the crystallization behavior in phase separated chalcogenide glasses in the GeSe2-As2Se3-PbSe glass system. Specifically, the research presented in this thesis work has …

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Microgrid Control And Protection: Stability And Security, Morteza Keshavarztalebi Jan 2016

Microgrid Control And Protection: Stability And Security, Morteza Keshavarztalebi

Electronic Theses and Dissertations

When the microgrid disconnects from the main grid in response to, say, upstream disturbance or voltage fluctuation and goes to islanding mode, both voltage and frequency at all locations in the microgrid have to be regulated to nominal values in a short amount of time before the operation of protective relays. Motivated by this, we studied the application of intelligent pinning of distributed cooperative secondary control of distributed generators in islanded microgrid operation in a power system. In the first part, the problem of single and multi-pinning of distributed cooperative secondary control of DGs in a microgrid is formulated. It …

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Modeling And Solving Large-Scale Stochastic Mixed-Integer Problems In Transportation And Power Systems, Zhouchun Huang Jan 2016

Modeling And Solving Large-Scale Stochastic Mixed-Integer Problems In Transportation And Power Systems, Zhouchun Huang

Electronic Theses and Dissertations

In this dissertation, various optimization problems from the area of transportation and power systems will be respectively investigated and the uncertainty will be considered in each problem. Specifically, a long-term problem of electricity infrastructure investment is studied to address the planning for capacity expansion in electrical power systems with the integration of short-term operations. The future investment costs and real-time customer demands cannot be perfectly forecasted and thus are considered to be random. Another maintenance scheduling problem is studied for power systems, particularly for natural gas fueled power plants, taking into account gas contracting and the opportunity of purchasing and …

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Reactive Rejuvenation Of Cmos Logic Paths Using Self-Activating Voltage Domains, Navid Khoshavi Najafabadi Jan 2016

Reactive Rejuvenation Of Cmos Logic Paths Using Self-Activating Voltage Domains, Navid Khoshavi Najafabadi

Electronic Theses and Dissertations

Aggressive CMOS technology scaling trends exacerbate the aging-related degradation of propagation delay and energy efficiency in nanoscale designs. Recently, power-gating has been utilized as an effective low-power design technique which has also been shown to alleviate some aging impacts. However, the use of MOSFETs to realize power-gated designs will also encounter aging-induced degradations in the sleep transistors themselves which necessitates the exploration of design strategies to utilize power-gating effectively to mitigate aging. In particular, Bias Temperature Instability (BTI) which occurs during activation of power-gated voltage islands is investigated with respect to the placement of the sleep transistor in the header …

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The Effect Of Vibrations On Cryogens Boil Off During Launch, Transfer And Transport, Erin Schlichenmaier Jan 2016

The Effect Of Vibrations On Cryogens Boil Off During Launch, Transfer And Transport, Erin Schlichenmaier

Electronic Theses and Dissertations

Boil-off of a cryogenic fluid which is caused by the temperature difference between the fluid and its environment is a phenomenon which has long been studied and is well understood. However, vibrational excitation of a cryogenic storage tank and the fluid inside it also play a role in the loss of cryogens. Mechanical energy applied to the system in the form of vibrational input is converted into thermal energy via viscous damping of the fluid. As a result, when a storage tank full of cryogenic fluids is vibrated, it boils off at an increased rate. A series of experiments were …

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High Average Power Nanosecond Pulsed Tm:Fiber Laser For Pumping An Optical Parametric Oscillator, Ali Abdulfattah Jan 2016

High Average Power Nanosecond Pulsed Tm:Fiber Laser For Pumping An Optical Parametric Oscillator, Ali Abdulfattah

Electronic Theses and Dissertations

Thulium-doped fiber lasers operating with wavelengths in the vicinity of 2 µm are useful for several emerging applications including generating mid-IR light via nonlinear frequency conversion. In this study we describe the design and construction of a thulium fiber laser system comprising a master oscillator and a power amplifier. The first stage is a Q-switched, thulium-doped photonic crystal fiber oscillator utilizing an acousto-optic modulator to produce 65-80 nanosecond pulses. A diffraction grating in the cavity provides wavelength tunability from 1.8 – 2µm. The oscillator produced up to 3 W of average power and 150 µJ pulse energies, corresponding to 2.3 …

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Assessing The Effect Of Social Networks On Employee Creativity In A Fast-Food Restaurant Environment, Mitchell Rabinowitz Jan 2016

Assessing The Effect Of Social Networks On Employee Creativity In A Fast-Food Restaurant Environment, Mitchell Rabinowitz

Electronic Theses and Dissertations

Creativity has been widely recognized as critical to the economic success of organizations for over 60 years. Today, it is considered to be the most highly prized "commodity" of businesses. As such, there have been numerous efforts to better understand creativity with the goal of increasing individual creativity and therefore improving the economic success of organizations. An emerging area of research on creativity recognizes creativity as a complex, social process that is dependent upon many factors, including those of an environmental nature. In support of this perspective, a growing amount of research has investigated the effect of social networks on …

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Kinematical Modelling And Its Analytical Inverse Kinematic Solution For The Handling Mechanism Of An Agricultural Robot, Sinem Gozde Defterli Jan 2016

Kinematical Modelling And Its Analytical Inverse Kinematic Solution For The Handling Mechanism Of An Agricultural Robot, Sinem Gozde Defterli

Electronic Theses and Dissertations

Early detection of the crop diseases helps to prevent failure in the amount and the quality of the production. In agricultural robotics, the idea of a disease detection robot is a fresh and an innovative hot-button topic. The exclusion of the diseased parts from the strawberry plants for further analyses is one of the main tasks of a recently developed strawberry robot. To this purpose, the handling mechanism in the robot needs to achieve an accurate manipulation task to reach the target. Reaching, cutting and storing the diseased leaf are challenging and delicate processes during the procedure of the handling …

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Fabrication And Investigation Of An Enzyme-Free, Nanoparticle-Based Biosensor For Hydrogen Peroxide Determination, Craig Neal Jan 2016

Fabrication And Investigation Of An Enzyme-Free, Nanoparticle-Based Biosensor For Hydrogen Peroxide Determination, Craig Neal

Electronic Theses and Dissertations

Electrochemical biosensors often employ enzymes as detection elements. These sensors are highly selective towards target analytes, however the scope of their application is limited by the poor stability of the enzyme. In this study, multi-valent inorganic cerium oxide nanoparticles were used as detection elements for the analysis of hydrogen peroxide. The electrochemical response of the cerium oxide towards hydrogen peroxide analyte is defined through cyclic voltammetry and chronoamperometry. This response was found to be dependent on nanoparticle Ce3+:Ce4+ redox state ratio and this property is exploited to fabricate a biosensor. As produced, the biosensor demonstrated sensitivity at picomolar analyte concentrations. …

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Modeling Mass Transfer And Assessing Cost And Performance Of A Hollow Fiber Nanofiltration Membrane Process, David Yonge Jan 2016

Modeling Mass Transfer And Assessing Cost And Performance Of A Hollow Fiber Nanofiltration Membrane Process, David Yonge

Electronic Theses and Dissertations

Bench-scale water treatment testing of three next generation hollow-fiber (HF) nanofiltration (NF) membranes was conducted to characterize divalent ion rejection capabilities and investigate removal mechanisms. Existing mathematical models were investigated to describe solute transport using synthetic magnesium sulfate solutions including the size exclusion model, homogenous solution diffusion (HSD) model, dimensional analysis, and the HSD model incorporating film theory. Solute transport for two of the membranes were described by HSD theory and were predictive of their 90% divalent ion removal. A third membrane was more accurately modeled using size exclusion and was found to be predictive of its 40% divalent ion …

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Data Mining Models For Tackling High Dimensional Datasets And Outliers, Orestis Panos Panagopoulos Jan 2016

Data Mining Models For Tackling High Dimensional Datasets And Outliers, Orestis Panos Panagopoulos

Electronic Theses and Dissertations

High dimensional data and the presence of outliers in data each pose a serious challenge in supervised learning. Datasets with significantly larger number of features compared to samples arise in various areas, including business analytics and biomedical applications. Such datasets pose a serious challenge to standard statistical methods and render many existing classification techniques impractical. The generalization ability of many classification algorithms is compromised due to the so-called curse of dimensionality. A new binary classification method called constrained subspace classifier (CSC) is proposed for such high dimensional datasets. CSC improves on an earlier proposed classification method called local subspace classifier …

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Investigation Of The Effect Of Rain On Sea Surface Salinity, Andrea Santos Garcia Jan 2016

Investigation Of The Effect Of Rain On Sea Surface Salinity, Andrea Santos Garcia

Electronic Theses and Dissertations

The Aquarius/SAC-D mission provided Sea Surface Salinity (SSS), globally over the ocean, for almost 4 years. As a member of the AQ/SAC-D Cal/Val team, the Central Florida Remote Sensing Laboratory has analyzed these salinity measurements in the presence of precipitation and has noted the high correlation between the spatial patterns of reduced SSS and the spatial distribution of rain. It was determined that this is the result of a cause and effect relation, and not SSS measurement errors. Thus, it is important to understand these salinity changes due to seawater dilution by rain and the associated near-surface salinity strati?cation. This …

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A Biomechanical Comparison Between Expert And Novice Manual Materials Handlers Using A Multi-Joint Emg-Assisted Optimization Musculoskeletal Model Of The Lumbar Spine, Denis Gagnon, André Plamondon, Christian Larivière Jan 2016

A Biomechanical Comparison Between Expert And Novice Manual Materials Handlers Using A Multi-Joint Emg-Assisted Optimization Musculoskeletal Model Of The Lumbar Spine, Denis Gagnon, André Plamondon, Christian Larivière

Études primaires

Expertise is a key factor modulating the risk of low back disorders (LBD). Through years of practice in the workplace, the typical expert acquires high level specific skills and maintains a clean record of work-related injuries. Ergonomic observations of manual materials handling (MMH) tasks show that expert techniques differ from those of novices, leading to the idea that expert techniques are safer. Biomechanical studies of MMH tasks performed by experts/novices report mixed results for kinematic/kinetic variables, evoking potential internal effect of expertise. In the context of series of box transfers simulated by actual workers, detailed internal loads predicted by a …

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Subject-Specific Biomechanics Of Trunk: Musculoskeletal Scaling, Internal Loads And Intradiscal Pressure Estimation, F. Ghezelbash, A. Shirazi-Adl, N. Arjmand, Z. El-Ouaaid, A. Plamondon Jan 2016

Subject-Specific Biomechanics Of Trunk: Musculoskeletal Scaling, Internal Loads And Intradiscal Pressure Estimation, F. Ghezelbash, A. Shirazi-Adl, N. Arjmand, Z. El-Ouaaid, A. Plamondon

Études primaires

Development of a subject-specific computational musculoskeletal trunk model (accounting for age, sex, body weight and body height), estimation of muscle forces and internal loads as well as subsequent validation by comparison with measured intradiscal pressure in various lifting tasks are novel, important and challenging. The objective of the present study is twofold. First, it aims to update and personalize the passive and active structures in an existing musculoskeletal kinematics-driven finite element model. The scaling scheme used an existing imaging database and biomechanical principles to adjust muscle geometries/cross-sectional-areas and passive joint geometry/properties in accordance with subjects’ sex, age, body weight and …

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