Thermo-Mechanical System Identification of a Shape Memory Alloy Actuated Mechanism

Shape memory alloy (SMA) actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle is compared with that of a SMA actuated arm. This is accomplished by parametric analysis of a crank-slider kinematic mechanism actuated, first, with an experimentally characterized SMA wire and then an idealized musculotendon actuator based on actuation properties of muscles published in the literature. Next, equations of motion for the system dynamics of the SMA actuated mechanism are derived and phase portrait analysis is conducted varying system parameters around different operating points. The eigenvalues of the differential equation are examined around equilibrium points and a stiffness ratio metric is proposed to characterize dynamic stability based on system parameters. Next, a heat transfer model is proposed and energy analysis is conducted on each stage of phase transformation for the SMA wire. The unknown parameters in the heat transfer model are theoretically derived and an experimental system identification is conducted. A proof of concept antagonistic SMA actuated mechanism is designed and kinematic analysis is conducted on an experimental prototype

Everybody Is A Critic: A Guide to the Critical Evaluation of Visual Media for Generation Z

The youth of today, especially Generation Z, lack the ability to think critically. An area that seems to be especially difficult for Generation Z to critically evaluate is visual media. This is an issue because visual media has an influential hold (both emotionally and mentally) over this generation and is a key factor in swaying the opinions and behaviors of these young minds. Visual media is a powerful tool that. should continue to be used by future generations, but with the knowledge that there will always be potentially negative influences, and more importantly, ways to identify and defend against them. This thesis is designed to explore a possible method to combat this lack of critical thinking in a visual manner by creating a beginner’s guide to evaluating visual media. The most important question to answer was how exactly visual media is used to mentally and emotionally influence people. Initial research investigated four areas of influence that exist in nearly all visual media: color theory, symbolism, literature influence, and emotion. Literature reviews explored each of these areas in greater detail. Next, case studies reviewed other similar projects and how they tackled similar issues in a visual way. Then, content analysis was used to dig deeper into the four areas of interest: color theory, symbolism, literature influence, and emotions. Finally, concept mapping and image boards were used to begin testing and establishing the best ways to tackle the visual deliverables. In light of this research, it was determined that the deliverables would consist of five illustrations infused with color theory, symbolism, literature influence, and emotion, as well as four illustrated charts explaining the basics of each influential category, so the viewer can engage with the project

Extensive microscale N isotopic heterogeneity in chondritic organic matter

Introduction: H and N isotopic anomalies (mainly excesses of D and 15N) in organic matter from primitive meteorites and IDPs suggest preservation of presolar molecular cloud material [1-3]. However, there have been very few spatially correlated H and N studies for either chondrites or IDPs [4, 5]. We report C and N isotopic imaging data for organic matter from four meteorites and three IDPs. D/H imaging data for many of the same samples are presented in [6, 7] and bulk organic isotope data in [8]

Optimization of Soilless Media for Alkaline Irrigation Water

High root zone pH reduces nutrient availability and high alkalinity water is strongly buffered around an alkaline pH. Soilless media can be altered to improve nutrient availability. This study was conducted to optimize the composition of soilless media for use with high alkalinity water. Mixes of peat and/or perlite or vermiculite in 50/50 and 33/33/33 volumetric ratios were tested. In some studies, mixes were also amended with up to 2.4 g/L of dolomite limestone to neutralize the initial acidity of the peat. Mixes containing vermiculite settled more, had higher water holding capacity (WHC) and percent plant available water (%PAW), and similar air filled porosity (AFP), compared to mixes containing perlite. Dry mass was measured in corn, peas, tomatoes, and soybeans, and chlorophyll content was measured in corn. The addition of dolomite increased pH and decreased dry mass in corn, soybean, and tomato, but peas were unaffected. Chlorophyll content in corn also declined with increased amounts of dolomite. After a week of daily irrigation, pH 7.8 nutrient solution neutralized the acidity of the peat, without the need for addition of dolomite. Mixes containing vermiculite improved growth and chlorophyll concentration compared to mixes with perlite. The higher cation exchange capacity (CEC) of vermiculite-containing mixes may have improved nutrient availability. A soilless mix of only peat and vermiculite, in approximately equal volumes, resulted in the greatest growth and chlorophyll content when watered with high alkalinity nutrient solution

Real-Space, Real-Time Approach to Quantum-Electrodynamical Time-Dependent Density Functional Theory

The Quantum-Electrodynamical Time-Dependent Density Functional Theory (QED-TDDFT) equations are solved by time propagating the wave function on a tensor product of a Fock-space and real-space grid. Applications for molecules in cavities show the accuracy of the approach. Examples include the coupling strength and light frequency dependence of the energies, wave functions, optical absorption spectra, and Rabi splitting magnitudes in cavities, as well as a description of high harmonic generation in cavities