LARGE CHANNEL-FED ROOTLESS VOLCANIC CONE COMPLEX, LAKI, ICELAND

2017 ◽  
Author(s):  
Andrew P. de Wet ◽  
◽  
Christopher W. Hamilton ◽  
Stephen Scheidt ◽  
Lucas Zeller ◽  
...  
Keyword(s):  
Volcanic Cone ◽  
Large Channel

Design Optimization of an L-Shaped Extrusion Die

2009 ◽  
Author(s):  
Oktay Yilmaz ◽  
Hasan Gunes ◽  
Kadir Kirkkopru
Keyword(s):  
Simulated Annealing ◽  
Optimization Problem ◽  
Numerical Solutions ◽  
Latin Hypercube Sampling ◽  
Kriging Model ◽  
Narrow Channel ◽  
Geometric Parameters ◽  
Die Design ◽  
Dimensional Parameter ◽  
Large Channel

It is an important problem in the polymer extrusion of complex profiles to balance the flow at the die exit. In this paper, we employ simulated annealing-kriging meta-algorithm to optimize the geometric parameters of a die channel to obtain a uniform exit velocity distribution. Design variables for our optimization problem involve the suitable geometric parameters for the die design, which are the thickness of the large channel and the length of the narrow channel. Die balance is based on the deviation of the velocity with respect to the average velocity at the die exit. So the cost function for the optimization problem involves the minimization of this deviation. For the design of numerical experiments, we use Latin Hypercube Sampling (LHS) to construct the kriging model. Then, based on the LHS points, the numerical solutions are performed using Polyflow, a commercial software based on the finite element method and is specifically designed to simulate the flow and heat transfer of non-newtonian, viscoelastic fluids. In our simulations, a HDPE (high density polyethylene) is used as extrusion material. Having obtained numerical simulations for N = 60 LHS points in two-dimensional parameter space (t and L), the optimization of these parameters is carried out by Simulated Annealing (SA) method in conjunction with kriging model. We show that kriging model employed in SA algorithm can be used to optimize the die geometry.

Use of Lightweight Lime Mortar in the Construction of the West Church of Umm el-Jimal, Jordan: Radiocarbon Dating and Characterization

Radiocarbon ◽  
2016 ◽  
Vol 58 (3) ◽  
pp. 583-598 ◽  
Author(s):  
Khaled Al-Bashaireh
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Lightweight Concrete ◽  
Mineralogical Composition ◽  
The West ◽  
Volcanic Cone ◽  
X Ray ◽  
Inductively Coupled ◽  
Architectural Styles ◽  
Microscopic Features

AbstractLightweight concrete was widely used and mainly spread during the Roman period. This technology was used in the West Church, Umm el-Jimal, Jordan. The date of construction of the West Church is debated and different dates have been suggested based on its architectural styles and comparisons with other churches. This research aims to radiocarbon date the construction of the dome (church), archaeometrically characterize the mortar, and determine the source of the scoria. Three charcoals and two broken pieces comprising scoria from the mortar of the fallen dome and six large scoria samples from Quais cone were collected. The research used different analytical methods including accelerator mass spectrometry 14C, X-ray diffraction, petrographic microscopy, inductively coupled plasma mass spectrometry, and scanning electron microscopy-energy dispersive X-ray spectroscopy. 14C determinations dated the dome (church) to the Late Roman–Early Byzantine periods, which contradicted the archaeological data. Analytical results showed that the mortar is lime-based and hydraulic. The similarities in the mineralogical composition, macroscopic and microscopic features, and chemical composition (compared statistically) of the scoria samples and the short distance between Umm el-Jimal and the Quais volcanic cone very likely indicate that the Quais volcanic cone is the source of the scoria used in the fallen dome.

Transpedicular N-butyl cyanoacrylate–mediated percutaneous embolization of symptomatic vertebral hemangiomas

2013 ◽  
Vol 18 (5) ◽  
pp. 450-455 ◽  
Author(s):  
Kevin C. Yao ◽  
Adel M. Malek
Keyword(s):  
Blood Loss ◽  
Direct Injection ◽  
Transarterial Embolization ◽  
High Volume ◽  
Vascular Tumors ◽  
Intraoperative Blood Loss ◽  
Percutaneous Embolization ◽  
Direct Puncture ◽  
Tumor Embolization ◽  
Large Channel

Object The resection of spinal hemangiomas is often challenging because of characteristic high-volume and potentially prohibitive intraoperative blood loss. Although transarterial embolization can mitigate this risk, it can be suboptimal when tumor arterial supply is diffuse or poorly defined. The authors present their experience in the use of preoperative percutaneous direct injection of spinal hemangiomas with N-butyl cyanoacrylate (NBCA) as an effective preoperative adjunct that may reduce operative blood loss and facilitate resection of these vascular tumors. Methods Four patients with symptomatic spinal hemangiomas were treated using percutaneous transpedicular direct NBCA-Lipiodol injection; 2 patients had undergone prior spinal angiography, with suboptimal transarterial embolization in 1. Each patient underwent percutaneous bilateral transpedicular NBCA-assisted tumor embolization prior to resection. Retrospective analysis of operative times, blood loss, and clinical data is presented. Results There were no complications associated with the percutaneous NBCA embolization technique. The procedure was effective at facilitating tumor removal and minimizing intraoperative blood loss, especially at the vertebral body resection stage. Improved tumor filling was achieved as the filling characteristics of dilute NBCA-Lipiodol mixture within large-channel, high-flow hemangiomas were appreciated with experience. Conclusions Transpedicular NBCA direct-puncture embolization of spinal hemangiomas is an effective preoperative adjunct that facilitates resection of these highly vascular tumors. It is particularly useful when transarterial embolization is unsafe or suboptimal due to constraints imposed by the local angioarchitecture.

Urban and Community Fisheries Programs: Development, Management, and Evaluation

2008 ◽  
Keyword(s):  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Cost Savings ◽  
Urban Lake ◽  
Development Management ◽  
Small Channel ◽  
Large Channel ◽  
P 16 ◽  
Community Fisheries ◽  
Catch Rates

<em>Abstract.-</em>Little published information exists on the utility of tournament and anglercatch data for assessing sizes and numbers of channel catfish <em>Ictalurus punctatus</em>. We compared channel catfish caught concurrently from May-August 2006 by small tournament anglers, creel-surveyed anglers, and soybean-baited tandem hoop nets (nets) in Lake Manawa, an 800 ac urban lake in Council Bluffs, Iowa. Mean total length of channel catfish caught was lowest in the nets, intermediate for creel-surveyed anglers, and highest for tournament anglers. Tournament anglers selected against small channel catfish (i.e., RSD S-Q: 11-16 in), selected for intermediate-sized channel catfish (RSD Q-P: 16-24 in), and caught similar proportions of large channel catfish (RSD P-M: 24-28 in) as compared to creel-surveyed anglers. Comparisons of angler and net catch rates by size categories revealed that both tournament and creel-surveyed anglers selected against small channel catfish, but overestimated both intermediate and larger channel catfish. We believe there is some utility and cost-savings benefits associated with using angler-caught channel catfish data for making management decisions, but biases need to be considered and more information on comparisons between angler caught channel catfish and sampling data are warranted.

scholarly journals Untangling the sequence of events during the S2→ S3transition in photosystem II and implications for the water oxidation mechanism

2020 ◽  
Vol 117 (23) ◽  
pp. 12624-12635 ◽  
Author(s):  
Mohamed Ibrahim ◽  
Thomas Fransson ◽  
Ruchira Chatterjee ◽  
Mun Hon Cheah ◽  
Rana Hussein ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Water Oxidation ◽  
Donor Site ◽  
Oxidation Mechanism ◽  
Oxygenic Photosynthesis ◽  
Acceptor Site ◽  
Oxygen Evolving Complex ◽  
Ps Ii ◽  
Sequence Of Events ◽  
Large Channel

In oxygenic photosynthesis, light-driven oxidation of water to molecular oxygen is carried out by the oxygen-evolving complex (OEC) in photosystem II (PS II). Recently, we reported the room-temperature structures of PS II in the four (semi)stable S-states, S1, S2, S3, and S0, showing that a water molecule is inserted during the S2→ S3transition, as a new bridging O(H)-ligand between Mn1 and Ca. To understand the sequence of events leading to the formation of this last stable intermediate state before O2formation, we recorded diffraction and Mn X-ray emission spectroscopy (XES) data at several time points during the S2→ S3transition. At the electron acceptor site, changes due to the two-electron redox chemistry at the quinones, QAand QB, are observed. At the donor site, tyrosine YZand His190 H-bonded to it move by 50 µs after the second flash, and Glu189 moves away from Ca. This is followed by Mn1 and Mn4 moving apart, and the insertion of OX(H) at the open coordination site of Mn1. This water, possibly a ligand of Ca, could be supplied via a “water wheel”-like arrangement of five waters next to the OEC that is connected by a large channel to the bulk solvent. XES spectra show that Mn oxidation (τ of ∼350 µs) during the S2→ S3transition mirrors the appearance of OXelectron density. This indicates that the oxidation state change and the insertion of water as a bridging atom between Mn1 and Ca are highly correlated.

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