Isogeometric analysis of ice accretion on wind turbine blades

For wind turbines operating in cold weather conditions, ice accretion is an established issue that remains an obstacle in effective turbine operation. While the aerodynamic performance of wind turbine blades with ice accretion has received considerable research attention, few studies have investigated the structural impact of blade ice accretion. This work proposes an adaptable projection-based method to superimpose complex ice configurations onto a baseline structure. The proposed approach provides an efficient methodology to include ice accretion in the high fidelity isogeometric shell analysis of a realistic wind turbine blade. Linear vibration and nonlinear deflection analyses of the blade are performed for various ice configurations to demonstrate the impact of different ice accretion distributions on structural performance. These analyses indicate decreases in the blade natural frequencies and deflection under icing conditions. Such ice-induced changes clearly reveal the need for structural design consideration for turbines operating under icing conditions

Analyzing The Effectiveness Of The Gurney Method For Small Scale Fragmentation Propulsion Using Exploding Bridgewire Detonators

Explosives are common in military, mining, and construction applications where the explosive properties are understood, but mechanics of how the explosive\u27s energy fragments and throws materials are less known. Considering the type of confining material around an explosive, creates variability in fragmentation behavior due to the individual material characteristics. The most common method for assessing fragmentation behavior is the Gurney method, which eliminates any consideration of fragmenting material properties. The Gurney method assumes that, on a large scale, the inconsistencies in material are irrelevant and only the mass of the confiner need be considered. However, it is known in many fields that energy is consumed in the breaking of a material. In this paper, the detonation and resultant fragmentation propulsion of Exploding Bridgewire (EBW) detonators with the same explosive material, but different casing characteristics, is observed. The Gurney method was used to predict fragmentation velocities of the casing following detonation, which were compared to the behavior observed through high-speed video of the actual event. The EBWs were selected to provide variability in casing material, casing thickness, charge length, and charge diameter. It was found that when the amount of explosive is small, the material properties of the casing play a significant role, with 70 % of the total explosive mass lost in fragmenting PMMA EBWs and 30±3 % lost in Aluminum EBWs. There is significant energy loss to breaking the casing material that cannot be ignored on the small scale and could impact large explosives with high casing to explosive ratios

The Ground on Which We All Stand: A Conversation About Menstrual Equity Law and Activism

This essay grows out of a panel discussion among five lawyers on the subject of menstrual equity activism. Each of the authors is a scholar, activist or organizer involved in some form of menstrual equity work. The overall project is both enriched and complicated by an intersectional analysis. This essay increases awareness of existing menstrual equity and menstrual justice work; it also identifies avenues for further inquiry, next steps for legal action, and opportunities that lie ahead. After describing prior and current work at the junction of law and menstruation, the contributors evaluate the successes and limitations of recent legal changes. The authors then turn to conceptual issues about the relationship between menstrual equity and gender justice, as well as the difference between equity and equality. The essay concludes with consideration of the future of menstrual equity and menstrual justice work. The authors envision an expanded, inclusive group of individuals working for greater gender justice

FAFSA Completion: Considerations for an Extension-Led Statewide Nudge Campaign

Eight U.S. states have enacted legislation that mandates high school seniors to act on the Free Application for Federal Student Aid (FAFSA) before graduation. At least 10 other states are considering implementing similar FAFSA requirements. While proponents of the law believe it will affect postsecondary education and the workforce positively, dissenters argue that the policy is an unfunded mandate that taxes students and parents without offering adequate resources. This article synthesizes existing literature related to policy-related nudge campaigns to provide an Extension-led, cost-effective strategy to achieve the FAFSA mandate’s goal and improve citizens’ FAFSA completion behavior

Water-Cased Kicker Charges for Use in Explosive Demolition

Demolition Projects Involving Explosives Often Incorporate Cutting Charges to Sever Columns in Conjunction with Kicker Charges that Move the Columns Out of Alignment. Traditional Kicker Charges Use Dynamite Secured to the Column above a Linear-Shaped Cutting Charge. This Study Investigates the Use of Water-Cased Kicker Charges for Use in Explosive Demolition. the Goal is to Reduce the Fragmentation of Steel Members and the Quantity of Explosive Needed Due to the Increased Density, Incompressibility, and Impedance Mismatch Water Provides. Simulations and Experimental Tests Were Utilized to Determine What Type of Charges Provide the Optimal Column Movement and Water Placement. Water Charges and Traditional Charges Were Placed on Hanging Steel Columns that Swung Freely from a Top Pivot and Analyzed for the Fragmentation and Velocity of the Column. Tests Were Recorded with High-Speed Video to Calculate Velocity and Impulse. Simulations Showed the Same Results as Experimental Tests, with Water-Cased Charges Moving the Column Faster and with More Impulse Than Traditional Charges. Experimental Testing Showed that Water-Cased Charges Moved the Column 53% Faster Than Traditional in Contact Charges While Simulations Showed that Water-Cased Charges Moved the Column 43% Faster Than Traditional in Contact Charges. Simulations Showed the Water Tamped Behind the Charge Increased Beam Velocity 32% While Water in Front of the Charge Reduced Pressure 38% through Dispersion

Effect Of Shock Tunnel Geometry On Shockwave And Vortex Ring Formation, Propagation, And Head On Collision

Vortex ring research primarily focuses on the formation from circular openings. Consequently, the role of tunnel geometry is less understood, despite there being numerous research studies using noncircular shock tunnels. This experimental study investigated shockwaves and vortex rings from different geometry shock tunnels from formation at the tunnel opening to head on collision with another similarly formed vortex ring using schlieren imaging and statistical analysis. The velocity of the incident shockwave was found to be consistent across all four shock tunnel geometries, which include circle, hexagon, square, and triangle of the same cross-sectional area. The velocity was 1.2 ± 0.007 Mach and was independent of the tunnel geometry. However, the velocities of the resulting vortex rings differed between the shapes, with statistical analysis indicating significant differences between the triangle and hexagon vortex velocities compared to the circle. Vortex rings from the square and circle shock tunnels were found to have statistically similar velocities. All vortex rings slowed as they traveled due to corner inversion and air drag. All shock tunnels with corners produce a wobble in the vortex rings. Vortex rings interact with opposing incident shockwaves prior to colliding with each other. Vortex velocity before and after shock-vortex interaction was measured and evaluated, showing statistically similar results. Shock-vortex interaction slows the shockwave upon interaction, while the shock-shock interaction resulted in no change in shock velocity. Although the vortex rings travel at different velocities, all head-on vortex ring collisions produce a perpendicular shockwave that travels at 1.04 ± 0.005 Mach

Every Juror Wants a Story: Narrative Relevance, Third Party Guilt and the Right to Present a Defense

On occasion, criminal defendants hope to convince a jury that the state has not met its burden of proving them guilty beyond a reasonable doubt by offering evidence that someone else (a third party) committed the crime. Currently, state and federal courts assess the admissibility of evidence of third-party guilt using a variety of standards. In general, however, there are two basic approaches. Many state courts require a defendant to proffer evidence of some sort of direct link or connection between a specific third-party and the crime. A second group of state courts, as well as federal courts, admit evidence of third-party guilt if it is relevant under Federal Rule of Evidence 401, or its state equivalent, and not excluded by other rules of evidence, such as 403. While some scholars have lauded the 401/403 approach as the better test, in practice the two tests operate in much the same way and the evidentiary bottom line is that the defendant\u27s evidence is frequently deemed inadmissible. Courts have offered two justifications for the strict restrictions on third-party guilt evidence: (1) to prevent juror confusion; and, (2) to guard against fabricated statements by third parties. We explain why these fears are unfounded, and then turn to the focus of this article: the importance of narrative relevance. Existing evidentiary restrictions fail to consider the role third party guilt evidence plays in shaping the narrative, or story, that the defendant will present to the jury in his defense. Empirical studies have shown that - more than legal standards, definitions or instructions - narrative plays a key role in the juror decision-making process. Without a thorough understanding and consideration of the narrative relevance of third party guilt evidence, restrictions on its use cannot be and are not being appropriately applied because they fail to account for the way in which jurors actually think and process information at trial. After discussing the importance of narrative relevance, we propose a new test which is more consistent with a defendant\u27s constitutional rights to a fair trial and to present a complete defense. First, the threshold test for admissibility should be probable cause. If the evidence proffered by the defendant would permit the state to proceed with a criminal prosecution against the third party, then the defendant must be permitted to tell the story of third party guilt. A story for the goose is a story for the gander. Once, the threshold test is satisfied, we propose that, with one significant exception, a defendant should be permitted to admit third-party guilt evidence if that same evidence would be admissible against the third party were he the defendant. The exception is propensity evidence. There is no need to balance the probative value of the third-party guilt evidence against the danger of unfair prejudice because the third-party suffers no prejudice by the admission of the evidence at a trial in which he is not the accused. Thus, admission of propensity (or other character) evidence concerning a third party should not be precluded

Qualitative Exploration of Case Conferencing and Occupational Stress with Video Relay Interpreters

American Sign Language (ASL) interpreters working in Video Relay Service (VRS) call centers experience more occupational stress than interpreters working in community settings, leading to burnout, attrition, and loss of qualified interpreters for the Deaf and hard of hearing community. Case conferencing that incorporates the use of demand control schema (DC-S; Dean & Pollard, 2001) is an emergent strategy that may be effective in decreasing VRS interpreters’ stress and burnout but has yet to be thoroughly studied. The purpose of this exploratory, qualitative case study is to understand how participation in an adapted DC-S case conferencing group assisted VRS interpreters reducing occupational stress and attrition in VRS. Data from this study yielded four major themes: (1) reduction of occupational stress, (2) application of skills learned in groups, (3) integration into practice, and (4) retention in VRS. Although not a distinct theme, improvement in call center culture emerged as an additional finding. Our findings suggest that case conferencing is a helpful strategy to manage stressors that are unique to working in VRS and can promote interpreter retention

Every Juror Wants a Story: Narrative Relevance, Third Party Guilt and the Right to Present a Defense

On occasion, criminal defendants hope to convince a jury that the state has not met its burden of proving them guilty beyond a reasonable doubt by offering evidence that someone else (a third party) committed the crime. Currently, state and federal courts assess the admissibility of evidence of third-party guilt using a variety of standards. In general, however, there are two basic approaches. Many state courts require a defendant to proffer evidence of some sort of direct link or connection between a specific third-party and the crime. A second group of state courts, as well as federal courts, admit evidence of third-party guilt if it is relevant under Federal Rule of Evidence 401, or its state equivalent, and not excluded by other rules of evidence, such as 403. While some scholars have lauded the 401/403 approach as the better test, in practice the two tests operate in much the same way and the evidentiary bottom line is that the defendant\u27s evidence is frequently deemed inadmissible. Courts have offered two justifications for the strict restrictions on third-party guilt evidence: (1) to prevent juror confusion; and, (2) to guard against fabricated statements by third parties. We explain why these fears are unfounded, and then turn to the focus of this article: the importance of narrative relevance. Existing evidentiary restrictions fail to consider the role third party guilt evidence plays in shaping the narrative, or story, that the defendant will present to the jury in his defense. Empirical studies have shown that - more than legal standards, definitions or instructions - narrative plays a key role in the juror decision-making process. Without a thorough understanding and consideration of the narrative relevance of third party guilt evidence, restrictions on its use cannot be and are not being appropriately applied because they fail to account for the way in which jurors actually think and process information at trial. After discussing the importance of narrative relevance, we propose a new test which is more consistent with a defendant\u27s constitutional rights to a fair trial and to present a complete defense. First, the threshold test for admissibility should be probable cause. If the evidence proffered by the defendant would permit the state to proceed with a criminal prosecution against the third party, then the defendant must be permitted to tell the story of third party guilt. A story for the goose is a story for the gander. Once, the threshold test is satisfied, we propose that, with one significant exception, a defendant should be permitted to admit third-party guilt evidence if that same evidence would be admissible against the third party were he the defendant. The exception is propensity evidence. There is no need to balance the probative value of the third-party guilt evidence against the danger of unfair prejudice because the third-party suffers no prejudice by the admission of the evidence at a trial in which he is not the accused. Thus, admission of propensity (or other character) evidence concerning a third party should not be precluded

Ecophysiology of coral reef primary producers across an upwelling gradient in the tropical central Pacific

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, M. D., Fox, M. D., Kelly, E. L. A., Zgliczynski, B. J., Sandin, S. A., & Smith, J. E. Ecophysiology of coral reef primary producers across an upwelling gradient in the tropical central Pacific. Plos One, 15(2), (2020): e0228448, doi:10.1371/journal.pone.0228448.Upwelling is an important source of inorganic nutrients in marine systems, yet little is known about how gradients in upwelling affect primary producers on coral reefs. The Southern Line Islands span a natural gradient of inorganic nutrient concentrations across the equatorial upwelling region in the central Pacific. We used this gradient to test the hypothesis that benthic autotroph ecophysiology is enhanced on nutrient-enriched reefs. We measured metabolism and photophysiology of common benthic taxa, including the algae Porolithon, Avrainvillea, and Halimeda, and the corals Pocillopora and Montipora. We found that temperature (27.2–28.7°C) was inversely related to dissolved inorganic nitrogen (0.46–4.63 μM) and surface chlorophyll a concentrations (0.108–0.147 mg m-3), which increased near the equator. Contrary to our prediction, ecophysiology did not consistently track these patterns in all taxa. Though metabolic rates were generally variable, Porolithon and Avrainvillea photosynthesis was highest at the most productive and equatorial island (northernmost). Porolithon photosynthetic rates also generally increased with proximity to the equator. Photophysiology (maximum quantum yield) increased near the equator and was highest at northern islands in all taxa. Photosynthetic pigments also were variable, but chlorophyll a and carotenoids in Avrainvillea and Montipora were highest at the northern islands. Phycobilin pigments of Porolithon responded most consistently across the upwelling gradient, with higher phycoerythrin concentrations closer to the equator. Our findings demonstrate that the effects of in situ nutrient enrichment on benthic autotrophs may be more complex than laboratory experiments indicate. While upwelling is an important feature in some reef ecosystems, ancillary factors may regulate the associated consequences of nutrient enrichment on benthic reef organisms.This work was supported by funding from the Moore Family Foundation, the Gordon and Betty Moore Foundation, the Scripps family, and anonymous donors. The funders had no role in study design, data collection and analysis, or preparation of the manuscript