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RISS 인기검색어
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- 저자 : Stewart Ryan (검색결과 6 건)
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An agent-based blackboard system for multi-objective optimization
Stewart Ryan,Palmer Todd S,Bays Samuel 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.2
In the field of multi-objective optimization, there are a multitude of algorithms from which to choose. Each algorithm has strengths and weaknesses associated with the mechanics for finding the Pareto front. Recently, researchers have begun to examine how multi-agent environments can be used to help solve multi-objective optimization problems. In this work, we propose a multi-objective optimization algorithm based on a multi-agent blackboard system (MABS). The MABS framework allows for multiple agents to read and write pertinent optimization problem data to a central blackboard agent. Agents can stochastically search the design space, use previously discovered solutions to explore local optima, or update and prune the Pareto front. A centralized blackboard framework allows the optimization problem to be solved in a cohesive manner and permits stopping, restarting, or updating the optimization problem. The MABS framework is tested against three alternative optimization algorithms across a suite of engineering design problems and typically outperforms the other algorithms in discovering the Pareto front. A parallelizability study is performed where we find that the MABS is able to evaluate a set number of designs, which require an evaluation time ranging from 0 to 300 seconds, quicker than a traditional optimization algorithm: this fact becomes more apparent the longer it takes to evaluate a design. To provide context for the benefits provided by MABS, a real-world nuclear engineering design problem is examined. MABS is used to examine the placement of experiments in a nuclear reactor, where we are able to evaluate hundreds of configurations for experimental placement while maintaining a strict set of safety constraints.
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Eneko Larrañeta,Juan Domínguez-Robles,Martha Coogan,Emma Heaney,Sarah A. Stewart,Raghu Raj Singh Thakur,Ryan F. Donnelly 한국고분자학회 2019 Macromolecular Research Vol.27 No.4
Hydrogels have been extensively investigated as a platform for drug delivery. However, their use for the delivery of hydrophobic drugs has been limited by their incompatibility with hydrophobic drug molecules. The chemical modification of the structure of the hydrogels to include hydrophobic moieties has been proven to be a good alternative to increase the stability and solubility of hydrophobic drugs in the polymer matrix of the hydrogel. The inclusion of hydroxypropyl-β-cyclodextrins (HPBCD) and Tween® 85 (T85) within hydrogel matrices has the potential to improve hydrophobic drug loading and release. HPBCD have the ability to host hydrophobic drug molecules in their cone-like structure, forming inclusion complexes through host-guest interactions. On the other hand, T85 is an amphiphilic molecule and, consequently, has the potential to increase hydrophilic drug loading within the hydrogels. In the present work, a new type of hydrogel made from poly(methyl vinyl ether-co-maleic acid) (GAN) and poly(ethylene glycol) (PEG) containing T85 and HPBCD was synthesized for hydrophobic drug release. Hydrogels were based on GAN crosslinked (PEG) and HPBCD and/or T85 via an esterification in the solid state (solvent free). The synthesised hydrogels were characterised using Fourier transform infrared (FTIR) spectroscopy, swelling studies and contact angle measurements. The hydrogels showed swellings ranging from 140 to 180%. The inclusion of T85 in the hydrogels improved the wettability of the materials. On the other hand, the inclusion of HPBCD within the hydrogels decreased the wettability as the contact angle between the hydrogels and water increased with the HPBCD content. Finally, the materials were loaded with an ophthalmic drug, dexamethasone (DX). HPBC-containing hydrogels showed a higher DX uptake and, consequently, also a higher capacity of DX release. On the other hand, T85 containing hydrogels did not show any improvement over the hydrogels containing only GAN and PEG. The hydrogels were able to provide sustained DX release over periods of 6 h.
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Pil Man Park,Su Young Lee,Pue Hee Park,Hye Ryun An,J. Ryan Stewart,Héctor Genaro Ortiz Cano 한국화훼학회 2021 화훼연구 Vol.29 No.3
양액 pH가 에케베리아 생육과 색상에 미치는 영향을 알아 보기 위해 본 연구를 수행하였다. 에케베리아 ‘Perle von Nurnberg’ 품종을 선택하여 미국 유타주 프로보(Provo)시 소재 브리검영대학교 Plant and Wildlife 학과의 연구온실에서 수행되었다. 이 품종에 pH 4, pH 7 및 pH 10 3종류의 양액을 공급하여 연구를 수행하였다. 양액 pH 4 처리구에서는 초폭이 120.6mm로 pH 10 처리구의 105.3mm 보다 크게 자랐으며 유의성도 있었다. 하지만 엽장, 엽폭, 엽수에 있어서는 처리간 유의성은 없었다. pH meter를 통해서 식물체 즙액의 pH 를 측정하였는데 4.5에서 4.7 범위의 값을 보였으며 처리간 유의성은 없었다. 위의 결과로 양액의 pH는 식물체의 pH에 영향을 미치지 않는 것으로 판단되었다. 색차계를 이용하여 CIELAB 값을 측정하였을 때 pH 4 처리구에서의 적색도(a)는 -4.0이었으며 pH 10 처리구보다 더 녹색을 띠었다. 명도(L)과 황색도(b) 값은 처리간에 유의적인 차이가 없었다. HPLC를 통한 안토시아니딘 분석에서는 주로 cyanidin, delphinidin 및 pelargonidin의 함량이 모든 처리구에서 상대적으로 높게 나타났다. 공급양액의 pH가 상승함 따라 그 함량도 높아지는 경향을 보였다. Petunidin, malvidin 함량은 미량으로 존재하였으며, peonidin은 분석되지 않았다. 이상의 결과로부터 양액을 pH 10으로 처리하였을 때 에케베리아의 생육억제와 잎 착색에 가장 효과적임을 알 수 있었다. This experiment investigated the growth and leaf color of Echeveria ‘Perle von Nnurnberg’ in the experimental greenhouse of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah. For one month, this cultivar was grown with three pH levels in nutrient solutions of pH 4, 7, and 10. The plant diameter of pH 4 nutrient solution was 120.6 mm and significantly bigger than that of pH 10 (105.3 mm). However, there were no significant differences in leaf length, leaf width, and number of leaves. The plant pH was measured by leaf extraction using a pH meter. The pH values were 4.5–4.7, but not significantly different among the treatments. Our result showed that the pH of the nutrient solution did not affect the plant pH. Additionally, the CIELAB values of leaves were measured using a colorimeter. The redness (a) of leaves in pH 4 treatment was -4.0, and the leaf was more greenish than that of pH 10 treatment. The degrees of lightness (L) and yellowness (b) were not significantly different among the treatments. From high-performance liquid chromatography analysis (HPLC), cyanidin, delphinidin, and pelargonidin were mainly detected in the treatments. As the pH level of the nutrient solutions increased, these anthocyanidins contents trended to be high. The contents of petunidin and malvidin were relatively small, and peonidin was not detected in all treatments. we conclude that pH10 treatment of the nutrient solution was most effective for the growth retardation and coloration of leaf in Echeveria.
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