Showing papers by "Exponent published in 2022"
TL;DR: In this paper, current knowledge about the occurrence and fate of PPCPs in aquatic systems, including wastewater treatment plants (WWTPs) and natural waters around the world, is critically reviewed to inform the state of the science and highlight existing knowledge gaps.
81 citations
TL;DR: In this paper, a neural network-based model was employed to predict fretting crack lengths and corresponding SIF of the studied alloy as a function of the fretting contact radius, the maximum surface pressure, and shear traction.
22 citations
14 Mar 2022
TL;DR: Water samples from Narragansett Bay, the Providence River, the Sargasso Sea, and fulvic acid/saline (NaCl) solutions were examined for their ability to solubilize n-alkane (n-C16, n-C20), isoprenoid (pristane), naphthenic (tetradecahydrophenanthrene) and aromatic (phenanthrene, anthracene) hydrocarbons as mentioned in this paper .
Abstract: Water samples from Narragansett Bay, the Providence River, the Sargasso Sea, and fulvic acid/saline (NaCl) solutions were examined for their ability to solubilize n-alkane (n-C16, n-C20), isoprenoid (pristane), naphthenic (tetradecahydrophenanthrene) and aromatic (phenanthrene, anthracene) hydrocarbons. A 30-80% reduction in the dissolved organic content of the natural samples by activated charcoal and by ultraviolet oxidation resulted in 50-99% decrease in the amount of saturated hydrocarbons solubilized. This decrease was directly related to the amount of dissolved organic matter (D.O.M.) removed. The solubilities of the aromatic hydrocarbons were unaffected by the D.O.M. The solubility of phenanthrene is twenty times greater than its structural isomer, anthracene, regardless of the concentration of D.O.M.
25 Jul 2022
TL;DR: The revisión de la identidad cultural que acompaña la consolidación de los procesos nacionales in los países andinos se constituye en una tarea importante en los contextos de consolidacióón de proyectos regionales, ya que dan cuenta del dinamismo existente in la interacción humana and en el uso los símbolos y contenidos que se desarrollan en su interior and podría constituirse en a herramienta extra que permee la consolidation of dichos proysos as mentioned in this paper .
Abstract: La revisión de la identidad cultural que acompaña la consolidación de los procesos nacionales en los países andinos se constituye en una tarea importante en los contextos de consolidación de proyectos regionales, ya que dan cuenta del dinamismo existente en la interacción humana y en el uso los símbolos y contenidos que se desarrollan en su interior y podría constituirse en una herramienta extra que permee la consolidación de dichos proyectos. El constructivismo, como teoría que explica ese dinamismo en sus postulados, es uno de los marcos de referencia que podemos usar para aclarar esas interacciones y llevar a buen puerto las tareas por la integración social, política y económica en nuestro continente.
TL;DR: An extension to the dynamic thickened flame model for large-eddy simulations (DTFLES) is presented, which allows modeling highly stratified combustion and accounts for spatial variations of flow and combustion metrics.
26 Nov 2022
11 Mar 2022
TL;DR: In this article , experiments on the solubility behavior of No. 2 fuel oil showed that hydrocarbons can be dispersed in water in a soluble, a solubilized (colloidal micelles), and a particulate (accommodated) state.
Abstract: Dissolved organic matter (DOM) in sea water solubilizes certain classes of hydrocarbons (Boehm, 1973). Several chemical and biological consequences of this solubilization phenomenon were explored, Experiments on the solubility behavior of No. 2 fuel oil showed that hydrocarbons can be dispersed in water in a soluble, a solubilized (colloidal micelles), and a particulate (accommodated) state. A fractionation of hydrocarbon mixtures (e.g., fuel oil) in sea water occurs due to the differences in the solubility behavior of the various classes of hydrocarbons within the mixture.
16 Dec 2022
TL;DR: In this paper , the authors used Positive Matrix Factorization (PMF) as a method to unmix PAH fingerprints to its source classes, while overcoming the challenges of lack of source samples, different PAH signatures associated with different sources (or sometimes the same source), historical PAH sources long removed, urban sediment movement by boat traffic and, in turn, PAHs mixing, and weathering effects on PAH fingerprint.
Abstract: Abstract One of the challenges to apportioning PAH-related remedy costs at contaminated sediment Sites is unmixing of PAH fingerprints to PAH source classes (petrogenic, pyrogenic, and runoff, a derivative of petrogenic and pyrogenic sources). Unmixing of PAHs can be challenged by lack of source samples, different PAH signatures associated with different sources (or sometimes the same source), historical PAH sources long removed, urban sediment movement by boat traffic and, in turn, PAHs mixing, and weathering effects on PAH fingerprints. This work demonstrates using Positive Matrix Factorization (PMF) as a method to unmix PAH fingerprints to its source classes, while overcoming these challenges. A large PAH dataset (over 700 samples) assembled from contaminated urban sediment sites was used as an input to PMF. Using a 3-Factor PMF analysis, a petrogenic, pyrogenic, and runoff/weathered PAH end member fingerprints were identified. Different numerical mixing percentages of the PMF-identified end member sources were able to replicate the site-measured PAH fingerprints, with the percent contribution of each of the end members to each sediment sample calculated. In addition, the analysis calculated the percent contribution of each end member source to each PAH compound (e.g., benzo([a]pyrene). The demonstrated work provides a method to satisfy the unmixing of PAH fingerprints to its source classes, as a step towards apportioning of PAH contamination.