Power Systems Optimization to Analyze Renewable Energy Policy and Resource Diversity

This thesis is organized into two chapters, which will be submitted separately for publication. The abstracts for each chapter are given below. Chapter 1: Many state-level Renewable Portfolio Standards (RPS) include preferences for solar generation, with goals of increasing the diversity of new renewable generation, driving down solar costs, and encouraging the development of local solar industries. Depending on their policy design, these preferences can impact the RPS program costs and emissions reduction. This study introduces a method to evaluate the impact of these policies on costs and emissions, coupling an economic dispatch model with optimized renewable site selection. Three policy designs of an increased RPS in Michigan are investigated: 1) 20% Solar Carve-Out, 2) 5% Distributed Generation Solar Carve-Out, and 3) 3x Solar Multiplier. The 20% Solar Carve-Out scenario was found to increase RPS costs 28%, while the 5% Distributed Generation Solar Carve-Out increased costs by 34%. Both of these solar preferences had minimal impact on total emissions. The 3x Solar Multiplier decreases total RPS program costs by 39%, but adds less than half of the total renewable generation of the other cases, significantly increasing emissions of CO2, NOx , and SO2 relative to an RPS without the solar credit multiplier. Sensitivity analysis of the installed cost of solar and the natural gas price finds small changes in the results of the Carve-Out cases, with a larger impact on the 3x Solar Multiplier. Setting the correct level for a solar multiplier to achieve one’s goals may prove difficult in light of changing costs associated with multiple technologies. The effective use of a credit multiplier can undermine objectives to increase renewable generation and decrease emissions, but do allow market forces to determine the level of solar development relative to other qualified renewable options. The Solar Carve-Out scenarios have a smaller impact on other non-solar related objectives, but may compel the development of high-cost solar, increasing the cost of implementing an RPS. Chapter 2: The variability of wind power introduces new challenges for the operation of the power system, including increased system ramping requirements. One method to reduce wind variability is to diversify the wind power resource by interconnecting diverse wind resources across a larger geography. This study uses a modified version of mean-variance portfolio optimization (MVP) to assess the potential for diverse wind to reduce the impacts of wind variability. To understand the value of the reduced variability to the power system, different portfolios of wind power are assessed using a unit commitment and economic dispatch model. Using MVP, diverse wind portfolios are shown to significantly reduce wind power variability, at the cost of increased installed wind capacity to meet the same level of wind generation of less diverse wind portfolios. However, the value of the reduced variability is complicated by complexities of the power system, including transmission constraints and the time of day of ramping need.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/109710/1/Novacheck_Thesis_December_2014.pd

The biomechanics of running

Abstract This review article summarizes the current literature regarding the analysis of running gait. It is compared to walking and sprinting. The current state of knowledge is presented as it fits in the context of the history of analysis of movement. The characteristics of the gait cycle and its relationship to potential and kinetic energy interactions are reviewed. The timing of electromyographic activity is provided. Kinematic and kinetic data (including center of pressure measurements, raw force plate data, joint moments, and joint powers) and the impact of changes in velocity on these findings is presented. The status of shoewear literature, alterations in movement strategies, the role of biarticular muscles, and the springlike function of tendons are addressed. This type of information can provide insight into injury mechanisms and training strategies

The biomechanics of running

Abstract This review article summarizes the current literature regarding the analysis of running gait. It is compared to walking and sprinting. The current state of knowledge is presented as it fits in the context of the history of analysis of movement. The characteristics of the gait cycle and its relationship to potential and kinetic energy interactions are reviewed. The timing of electromyographic activity is provided. Kinematic and kinetic data (including center of pressure measurements, raw force plate data, joint moments, and joint powers) and the impact of changes in velocity on these findings is presented. The status of shoewear literature, alterations in movement strategies, the role of biarticular muscles, and the springlike function of tendons are addressed. This type of information can provide insight into injury mechanisms and training strategies

A randomised controlled trial of laser scanning and casting for the construction of ankle foot orthoses

Study Design: Randomised controlled trial with blinding of orthotists and patients to the construction technique used. Background: Three-dimensional laser scanning has been used for patient measurement for cranial helmets and spinal braces. Ankle foot orthoses are commonly prescribed for children with orthopaedic conditions. This trial sought to compare ankle foot orthoses produced by laser scanning or traditional plaster casting. Objectives: Assessment of the effectiveness and efficiency of using laser scanning to produce AFOs. Methods: A randomised double blind trial comparing fabrication of AFOs from casts or laser scans. Results: The time spent in the rectification and moulding of scanned AFOs was around 50% less than for cast AFOs. A non-significant increase of 9 days was seen in the time to delivery to the patient for LSCAD/CAM. There was a higher incidence of problems with the scan-based AFOs at delivery of the device, but no difference in how long the AFOs lasted. Costs associated with laser scanning were not significantly different from traditional methods of AFO manufacture. Conclusions: Compared with conventional casting techniques laser scan based AFO manufacture neither significantly improved the quality of the final product nor delivered a useful saving in time

TTN genotype is associated with fascicle length and marathon running performance.

Titin provides a molecular blueprint for muscle sarcomere assembly and sarcomere length can vary according to titin isoform expression. If variations in sarcomere length influence muscle fascicle length, this may provide an advantage for running performance. Thus the aim of this study was to investigate if the titin (TTN) rs10497520 polymorphism was associated with muscle fascicle length in recreationally active men (RA; n = 137) and marathon personal best time in male marathon runners (MR; n = 141). Fascicle length of the vastus lateralis was assessed in vivo using B-mode ultrasonography at 50% of muscle length in RA. All participants provided either a whole blood, saliva or buccal cell sample, from which DNA was isolated and genotyped using real-time polymerase chain reaction. Vastus lateralis fascicle length was 10.4% longer in CC homozygotes, those carrying two copies of the C-allele, than CT heterozygotes (p = 0.003) in RA. In the absence of any TT homozygotes, reflective of the low T-allele frequency within Caucasian populations, it is unclear if fascicle length for this group would have been smaller still. No differences in genotype frequency between the RA and MR groups were observed (p = 0.500), although within the MR group the T-allele carriers demonstrated marathon personal best times 2 min 25 s faster than CC homozygotes (p = 0.020). These results suggest that the T-allele at rs10497520 in the TTN gene is associated with shorter skeletal muscle fascicle length and conveys an advantage for marathon running performance in habitually trained men. This article is protected by copyright. All rights reserved

Influence of Kinematics on the Wear of a Total Ankle Replacement

Total ankle replacement (TAR) is an alternative to fusion, replacing the degenerated joint with a mechanical motion-preserving alternative. Minimal pre-clinical testing has been reported to date and existing wear testing standards lack definition. Ankle gait is complex, therefore the aim of this study was to investigate the effect on wear of a range of different ankle gait kinematic inputs. Five Zenith (Corin Group) TARs were tested in a modified knee simulator for twelve million cycles (Mc). Different combinations of IR rotation and AP displacement were applied every 2Mc to understand the effects of the individual kinematics. Wear was assessed gravimetrically every Mc and surface profilometry undertaken after each condition. With the initial unidirectional input with no AP displacement the wear rate measured 1.2±0.6 mm3/Mc. The addition of 11° rotation and 9 mm of AP displacement caused a statistically significant increase in the wear rate to 25.8±3.1 mm3/Mc. These inputs seen a significant decrease in the surface roughness at the tibial articulation. Following polishing three displacement values were tested; 0, 4 and 9 mm with no significant difference in wear rate ranging 11.8–15.2 mm3/Mc. TAR wear rates were shown to be highly dependent on the addition of internal/external rotation within the gait profile with multidirectional kinematics proving vital in the accurate wear testing of TARs. Prior to surface polishing wear rates were significantly higher but once in a steady state the AP displacement had no significant effect on the wear

Could relative movement between the adductor muscles and the skin invalidate surface electromyography measurement?

The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque–EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion–extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derive meaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors

Assessment of foot alignment and function for ambulatory children with cerebral palsy: Results of a modified Delphi technique consensus study

PURPOSE The purpose of this study was to establish consensus for the assessment of foot alignment and function in ambulatory children with cerebral palsy, using expert surgeon's opinion through a modified Delphi technique. METHODS The panel used a five-level Likert-type scale to record agreement or disagreement with 33 statements regarding the assessment of foot alignment and function. Consensus was defined as at least 80% of responses being in the highest or lowest of two of the five Likert-type ratings. General agreement was defined as 60%-79% falling into the highest or lowest two ratings. There was no agreement if neither threshold was reached. RESULTS Consensus was achieved for 25 (76%) statements, general agreement for 4 (12%) statements, and lack of consensus for 4 (12%) of the statements. There was consensus that the functional anatomy of the foot is best understood by dividing the foot into three segments and two columns. Consensus was achieved concerning descriptors of foot segmental alignment for both static and dynamic assessment. There was consensus that radiographs of the foot should be weight-bearing. There was general agreement that foot deformity in children with cerebral palsy can be classified into three levels based on soft tissue imbalance and skeletal malalignment. CONCLUSION The practices identified in this study can be used to establish best care guidelines, and the format used will be a template for future Delphi technique studies on clinical decision-making for the management of specific foot segmental malalignment patterns commonly seen in children with cerebral palsy. LEVEL OF EVIDENCE V