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Full-Text Articles in Engineering

Further Exploration Of Optical/Thermal Interaction Effects On High-Power Laser System Performance And Optimization Through Multiphysics System-Level Modeling, Nathaniel J. Butt Jan 2022

Further Exploration Of Optical/Thermal Interaction Effects On High-Power Laser System Performance And Optimization Through Multiphysics System-Level Modeling, Nathaniel J. Butt

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High-power laser systems (HPLS) have wide-ranging applications in many prominent areas. HPLS use laser diodes to pump fiber gain media. Understanding the functionality of both components is critical for achieving effective HPLS operation. System optical efficiency is a function of diode junction temperature. As junction temperature changes, the wavelength spectrum of the diode output shifts causing optical power losses in the fiber gain media. Optical/thermal interactions of the dynamically coupled laser diodes and fiber gain media are not fully understood. A system level modeling approach considering the interactions between optical performance and component temperature is necessary. Four distinct models were …


Studies Of Ionic Liquid Hybrids: Characteristics And Their Potential Application To Li-Ion Batteries And Li-Ion Capacitors, Mengxin Liu Jan 2017

Studies Of Ionic Liquid Hybrids: Characteristics And Their Potential Application To Li-Ion Batteries And Li-Ion Capacitors, Mengxin Liu

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Ionic liquids (ILs) have attracted much attention in electrochemical energy storage systems for their advantageous properties over traditional lithium salt/carbonate solvent electrolyte in terms of higher electrochemical potential windows, comparable ionic conductivity, negative vapor pressure and non-flammability. Ionic liquids can be used as the solvent-free electrolyte in electrochemical double layer capacitors (EDLCs) or can act as the important additives to the carbonate electrolyte in lithium ion batteries (LIBs). Recently, lithium ion capacitors (LICs) have emerge as a novel energy storage system to satisfy the demands for higher energy density and higher power density in portable and transportation systems. This Master …


Ab Initio Study Of The Effects Of Humidity On Perovskite Based Hybrid Solar Cell Interfaces, Shantanu Rajendra Rachalwar Jan 2017

Ab Initio Study Of The Effects Of Humidity On Perovskite Based Hybrid Solar Cell Interfaces, Shantanu Rajendra Rachalwar

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Despite the impressive success of perovskite-based hybrid solar cells, their widespread usage has been limited partially owing to stability issues under working environmental conditions. Among these, the effects of humidity are some of the most significant. Water intercalation generally degrades the material, shortens its useful life, and reduces the efficiency of photovoltaic energy conversion. Understanding the reasons for these effects can be achieved through detailed and accurate atomic-scale analysis. Here, we study water intercalation at the interfaces of perovskite-based hybrid solar cell material and TiO2 electrode. Accurate ab initio computer simulations are used to obtain structural and electronic properties. We …


Configuration And Electronic Properties Of The Interface Between Lead Iodide Hybrid Perovskite And Self-Assembled Monolayers In Solar Cells, Parin Divya Amlani Jan 2017

Configuration And Electronic Properties Of The Interface Between Lead Iodide Hybrid Perovskite And Self-Assembled Monolayers In Solar Cells, Parin Divya Amlani

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Hybrid perovskite photovoltaic materials are currently the most promising functional materials for solar cell applications with efficiency reaching to those of more conventional materials such as silicon. Using self-assembled monolayers between photovoltaic materials and electrodes is a method for improving the stability and functionality. Recent experiments have shown that using 4-mercaptobenzoic acid and pentafluorobenzenethiol monolayers bridging lead iodide hybrid perovskite photovoltaic materials and electrodes result in improved stability and efficiency. The details of monolayer assembly, molecular adsorption configuration, and resulting modification of electronic properties are important characteristics related to solar cell performance. These characteristics can be obtained through accurate computer …


Dynamic Modeling Of Thermal Management System With Exergy Based Optimization, Marcus J. Bracey Jan 2017

Dynamic Modeling Of Thermal Management System With Exergy Based Optimization, Marcus J. Bracey

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System optimization and design of aircraft is required to achieve many of the long term objectives for future aircraft platforms. To address the necessity for system optimization a vehicle-level aircraft model has been developed in a multidisciplinary modeling and simulation environment. Individual subsystem models developed exclusively in MATLAB-SimulinkTM, representing the vehicle dynamics, the propulsion, electrical power, and thermal systems, and their associated controllers, are combined to investigate the energy and thermal management issues of tactical air vehicle platforms. A thermal vehicle level tip-to-tail model allows conceptual design trade studies of various subsystems and can quantify performance gains across the aircraft. …