2,220 research outputs found
Ash Thye Interview
No full textAsh Thye (Class of 2023) was interviewed by Michelle Ma in the Oral History Studio in Fondren Library at Southern Methodist University on September 14, 2023. Mr. Thye grew up in the Mid-Cities region of Texas between Dallas and Fort Worth with two younger siblings and his mother. He came out as transgender at the end of middle school. Growing up, his family was food-and housing-insecure which influenced his interest in social justice. He became interested in SMU through a career day event where representatives from the SMU Human Rights Program spoke. He graduated from SMU in 2023 with bachelor's degrees in Human Rights and Anthropology and a minor in Photography. His issues with SMU's housing department as an incoming freshman led the university to overhaul its housing portal to make it trans-inclusive. While at SMU, Mr. Thye worked on the Rotunda Yearbook as a photographer and led the Period Project, which works to make free menstruation products available in restrooms across campus. He also assisted with the Pride Project, which investigates the history of SMU's queer community through archival research and oral history interviews, as well as putting on an annual Pride Visibility Day event, and served on the Human Rights Council. His senior year, he spent time in Austin testifying on anti-transgender legislation at the State Capitol. He expressed disappointment that SMU does not make resource access for marginalized students a staff priority, noting that students should be able to focus on their schooling without having to worry about advocating for themselves. Since graduating, he has taken two study abroad trips to Ireland and South Africa. At the time of the recording he was working as a farmer. He hopes to attend a Master's program for Public Humanities in the future
The density, construction and drag coefficient of electrostatic volcanic ash aggregates.
Get PDFRecent laboratory experiments have demonstrated that electrostatic charges generated during the fragmentation of volcanic pumice cause rapid aggregation of the silicate particles produced. Here, we present measurements of the mass and component particle size distribution of individual, electrostatically bound aggregates produced during these experiments. Particles produced by fracturing pumice aggregated as they fell ∼1.5 m within an enclosed fall chamber. Aggregate mass measurements indicate aggregate densities of ∼200 kg m−3 or less. The component particle size analysis demonstrates exponential-type cumulative distributions which are dominated (on a volume basis) by particles ∼10–40 μm in diameter and contain few particles >70 μm. By representing these particles as disks of 5 μm thickness the calculated aggregate densities are in agreement with those derived from the aggregate mass measurements and indicate a relatively constant aggregate density with size (in contrast with previous results from fall velocities). Combining the density measurements with fall velocity data allows the drag coefficient of aggregates to be determined. Empirical equations developed to describe the particle size distribution within aggregates are used to derive relative aggregation coefficients for the electrostatic aggregation process. Our results can be used within numerical models of volcanic plumes in order to improve their representation of electrostatic aggregation processes
From Dome to Disease: The Respiratory Toxicity of Volcanic Cristobalite
Get PDFExposure to fine-grained volcanic ash can potentially cause acute and chronic respiratory disease. The toxicity of ash is likely to vary depending on the type and style of eruption; eruptions at dome-forming volcanoes, in particular, can produce ash containing substantial quantities of respirable crystalline silica, a recognised human carcinogen and causative agent of silicosis. Volcanic domes crystallise crystalline silica as cristobalite, which is metastable at dome-forming temperatures (ca. 850 °C), through deposition from silica-saturated vapours and through devitrification of volcanic glass.
Five dome-forming volcanoes are studied to constrain the hazard posed by volcanic cristobalite, including: Colima, Mexico; Merapi, Indonesia; Mount St. Helens, USA; Santiaguito, Guatemala; and Unzen, Japan. The evolution of the cristobalite hazard is investigated from crystallisation in volcanic settings to its potential effect on biological systems, through a series of petrological, physicochemical and toxicological studies.
We rationalise the presence of metastable cristobalite below its stability field in all domes studied by way of a textural investigation, and conclude that the incorporation of aluminium and sodium into the silica structure facilitates crystallisation. Since particle toxicology is dependent on composition and structure, the observation of cation substitutions is expanded in a geochemical and thermodynamic investigation of volcanic cristobalite to constrain its mineralogy. We find that incorporation of 1-4 wt. % aluminium leads to a poorly-ordered cristobalite structure. This investigation facilitates a mineralogical comparison of the cristobalite hazard among volcanic locations and provides the framework for assessing volcanic cristobalite toxicity. We investigate the ability of volcanic ash to elicit an in vitro pro-inflammatory response, focusing on silica-mediated experiments, and relate the influence of structure and composition to the potential physiological burden. We find that volcanic cristobalite can be mineralogically considered as a single entity among locations, and that cristobalite-bearing ash is less toxic than expected. Nonetheless, we recommend that eruptions be considered on a case-by-case basis to most effectively aid the risk mitigation work of disaster managers globally
An advanced adjustable switch hybrid (Ash) concept for high power automotive converters
No full textIn this paper, we introduce an Adjustable Switch Hybrid (ASH) converter concept. The ASH targets the optimization of the electrical performance of high-powered automotive drive-trains depending on the different load conditions during drive cycles. The new concept employs in principle the previously reported Cross Switch (XS) Hybrid having a parallel arrangement of bipolar Silicon IGBTs and unipolar SiC MOSFETs for benefiting from the different electrical characteristics of each paralleled device. However, the ASH relies on a computational approach for the continuous and dynamic adjustments of the Si-IGBT to the SiC MOSFET area ratio through the gate units depending on the load conditions. In practical terms, changes in the loading conditions can be sensed and data will then be sent back to the ASH gate drive unit for the optimum device ratio selection. In other words, the ASH provides the drivetrain with an Electronic Transmission System or Gear type functionality.Accepted Author ManuscriptDC systems, Energy conversion & Storag
Nathan Gray : What they brought back
No full textPublished to accompany the exhibition held at Gertrude Contemporary Project Room, Melbourne Art Fair, 4-8 August 2010.Catalogue essay by Ash Kilmartin
Pore solution composition of alkali-activated slag/fly ash pastes
No full textThe pore solutions of a series of hardened alkali-activated slag/fly ash pastes were extracted by the steel-die method, and analyzed using ICP-OES analysis technique. According to the saturation index from thermodynamic calculations, the pore solutions of alkali-activated slag pastes kept oversaturated with respect to solid reaction products with time. In the pore solutions of alkali-activated fly ash pastes, an increase of temperature (from 40 °C to 60 °C) led to decreases of the concentrations of Si, Al, Ca, Na, OH−, K, Fe and Mg, while the soluble silicate in the alkaline activator resulted in increases of the concentrations of these elements. Compared to the alkali-activated slag paste with the same alkaline activator, 50% replacement of slag by fly ash did not result in a substantial change of the pore solution composition. Based on the experimental results, conceptual models were proposed to describe the elemental concentrations in the pore solutions.Accepted Author ManuscriptMaterials and Environmen
Creating coagulants through the combined use of ash and brine
No full textSludge incineration and seawater desalination are two approaches that can be used in the disposal of waste activated sludge (WAS) and for obtaining fresh water. As resource recovery from wastewater treatment and water purification is a topic of particular interest in these times, “water mining” has become a focus of research, with phosphate/P-recovery from WAS incineration ash, and extraction of useful elements from the brine of desalination being important steps in the pursuit of a circular/blue economy. However, P-recovery from ash involves removing metals, which need to be disposed of carefully, as does the brine collected. If cations in the ash and anions in the brine could be combined in order to produce coagulants/flocculants, a new circular model would be established. A preliminary experiment for this purpose has demonstrated that a liquid poly‑aluminum chloride (PAC) could be synthesized from the aluminum ion/Al3+ removed from the ash and the original brine. With this work, we synthesized the liquid PAC by a hydrothermal method, and the results from infrared spectrometer demonstrated that the synthesized PAC was similar to a commercial PAC. Moreover, the synthesized PAC was able to efficiently reduce the effluent turbidity of wastewater treatment plants (WWTPs), especially when compared with the commercial PAC. It is therefore important that research in this area be continued in order to improve the quality of synthesized coagulants and to produce different coagulants based on cations and anions in ash and brine.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog
Synergy of phosphate recovery from sludge-incinerated ash and coagulant production by desalinated brine
No full textWet-chemical approach is widely applied for phosphate recovery from incinerated ash of waste activated sludge (WAS), along with metals removed/recovered. The high contents of both aluminum (Al) and iron (Fe) in WAS-incinerated ash should be suitable for producing coagulants with some waste anions like Cl− and SO42− With acid (HCl) leaching and metals’ removing, approximately 88 wt% of phosphorus (P) in the ash could be recovered as hydroxylapatite (HAP: Ca5(PO4)3OH); Fe3+ in the acidic leachate could be selectively removed/recovered by extraction with an organic solvent of tributyl phosphate (TBP), and thus a FeCl3-based coagulant could be synthesized by stripping the raffinate with the original brine (containing abundant Cl− and SO42−). Furthermore, a liquid poly-aluminum chloride (PAC)-based coagulant could also be synthesized with Al3+ removed from the ash and the brine, which behaved almost the same in the coagulation performance as a commercial coagulant on both phosphate and turbidity removals. Both P-recovery from the ash and coagulant production associated with the brine would enlarge the markets of both ‘blue’ phosphate and ‘green’ coagulants.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog
A Review on the Effect of Fly Ash Characteristics and Their Variations on the Synthesis of Fly Ash Based Geopolymer
Get PDFThere are more than four decades since the last 1970s where geopolymers concrete was first introduced and developed to use as a replacement to conventional concrete material which uses cement as a binder. And since the last two decades, geopolymers which utilized fly ash as aluminosilicate source material, i.e. fly ash based geopolymers, have been investigated. Many researchers present how to produce the best fly ash based geopolymer with a various source of constituent material as well as mixing formula to achieve exceptional concrete performance. Although there is a similar trend towards factors affecting the result of fly ash based geopolymer synthesis, there is still remain a wide range in mixture proportion. The considerable variation in fly ash characteristics as source material in the synthesis can very likely be one of the causes of this problem. This paper attempts to identify the effect of source material variation of geopolymer concrete, particularly which use fly ash as source material and focuses on the variation of its characteristics and the effects to properties of concrete. From the reviews it concluded that different sources (and even the same source, but different batch) of fly ash materials will give some different characteristics of the fly ash, where it would affect the synthesis process of the fly ash based geopolymer concretes
The Effect of Wet Treatment on the Distribution and Leaching of Heavy Metals and Salts of Bottom Ash from Municipal Solid Waste Incineration
No full textOne of the main challenges of bottom ash reutilization is heavy metal and salts' leaching potential. The effect of wet treatment on chemical composition and leaching toxicity of bottom ash were investigated in this study to mitigate this leaching potential. Batch leaching and column leaching tests were first conducted to investigate the leaching behavior of the targeted elements (Cu, Zn, Ni, Cl-, and SO42-) from raw bottom ash and treated bottom ash after wet treatment. X-ray fluorescence analysis was used to analyze the chemical composition of bottom ash, and sequential extraction procedure (SEP) operation was done to analyze the chemical species of the heavy metals of bottom ash. The obtained results showed that the wet treatment applied on raw bottom ash posed a slight influence on the concentration of most of the major elements, 5.57-18.18%. SEP results showed the acid extractable Zn that accounted for 22.4-24.5% of the total Zn, and the iron manganese oxide bound Ni was 25.2-28.4%, and the organic matter bound Cu was 21.4-31.7%. The wet treatment reduced the concentrations and leachable amount of the targeted pollutants, which could decrease the leaching concentration of Cu by 77.1%, Zn by 34.7%, Ni by 100%, Cl by 30.1%, and SO42- by 51.4% based on the batch leaching tests under acid condition. The column leaching tests also suggest that wet treatment decreases Cu, Zn, and Cl- leaching concentration in bottom ash. This indicates that wet treatment improves the suitability of municipal solid waste incineration bottom ash for reutilization in China. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Resources & Recyclin
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