检索结果-南通市图书馆

An Optimized Divide-and-conquer Algorithm for the closest-Pair Problem in the Planar case

在线全文

学校读者我要写书评

暂无评论

Journal of computer science & Technology 2012年第4期27卷 891-896页

作者： José c.pereira fernando G.Lobo Department of Electronics and computer science University of AlgarveCampus de Gambelas8005-139 FaroPortugal Center for Environmental and Sustainability ResearchCampus de Caparica2829-516 CaparicaPortugal

We present an engineered version of the divide-and-conquer algorithm for finding the closest pair of points, within a given set of points in the XY-plane. For this version of the algorithm we show that only two pairwise comparisons are required in the combine step, for each point that lies in the 25-wide vertical slab. The correctness of the algorithm is shown for all Minkowski distances with p ≥ 1. We also show empirically that, although the time complexity of the algorithm is still O（n lgn）, the reduction in the total number of comparisons leads to a significant reduction in the total execution time, for inputs with size sufficiently large.

关键词： geometrical problem and computation closest-pair problem Basic-2 algorithm

Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2018年第1期25卷 11-19页

作者： Nathalia Vieceli carlos A.Nogueira Manuel F.c.pereira fernando O.Durao carlos Guimaraes Fernanda Margarido center for Innovation Technology and Po icy Research-IN+Instituto Superior T6cnicoUniversity of Lisbon1049-001 LisboaPortugal LNEG-Laborat6rio Nacional de Energia e Geologia I.P.Campus do Lumiar1649-038 LisboaPortugal cERENA-centro de Recursos Naturais e Ambiente DECivilInstituto Superior T6cnicoUniversity of Lisbon1049-001 LisboaPortugal

The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. There- fore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from le- pidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and re- sponse-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphi- zation and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.

关键词： lepidolite lithium mechanical activation acid digestion optimization extraction

Kinetic approach to the study of froth flotation applied to a lepidolite ore

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2016年第7期23卷 731-742页

作者： Nathália Vieceli fernando O.Durao carlos Guimaraes carlos A.Nogueira Manuel F.c.pereira Fernanda Margarido center for Innovation Technology and Policy Research-IN+Instituto Superior T6cnicoUniversity of Lisbon1049-001 LisboaPortugal cERENA-centro de Recursos Naturais e Ambiente DECivilInstituto Superior TecnicoUniversity of Lisbon1049-001 LisboaPortugal LNEG-Laboratorio Nacional de Energia e Geologia I.P.Campus do Lumiar1649-038 LisboaPortugal

The number of published studies related to the optimization of lithium extraction from low-grade ores has increased as the demand for lithium has grown. However, no study related to the kinetics of the concentration stage of lithium-containing minerals by froth flotation has yet been reported. To establish a factorial design of batch flotation experiments, we conducted a set of kinetic tests to determine the most selective alternative collector, define a range of pulp p H values, and estimate a near-optimum flotation time. Both collectors（Aeromine 3000 c and Armeen 12D） provided the required flotation selectivity, although this selectivity was lost in the case of pulp p H values outside the range between 2 and 4. cumulative mineral recovery curves were used to adjust a classical kinetic model that was modified with a non-negative parameter representing a delay time. The computation of the near-optimum flotation time as the maximizer of a separation efficiency（sE） function must be performed with caution. We instead propose to define the near-optimum flotation time as the time interval required to achieve 95%–99% of the maximum value of the sE function.

关键词： lepidolite lithium ore treatment froth flotation kinetic analysis

Effective and simple recovery of 1,3-propanediol from a fermented medium by liquid–liquid extraction system with ethanol and K_3PO_4

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemical Engineering 2018年第1期26卷 104-108页

作者： Daiana Wischral Hongxin Fu fernando L.Pellegrini Pessoa Nei pereira Jr shang-Tian Yang school of chemistry Department of Biochemical EngineeringFederal University of Rio de Janeiro William G.Lowrie Department of chemical and Biomolecular Engineering The Ohio State University school of chemistry Department of Chemical EngineeringFederal University of Rio de Janeiro

1,3-Propanediol,traditionally obtained from fossils,has numerous industrial applications,including use in the production of high performance *** microbial production of 1,3-propanediol presents several opportunities,and the final purity grade determines its price and commercial *** development of novel separation technology could improve the economic viability of the bioproduction of 1,***,we investigated salting-out extraction as a novel process for 1,3-propanediol recovery from fermentation ***,a screening for the best salt/solvent combination was conducted and then optimized using the response surface *** solvents studied were methanol,ethanol,isopropanol and acetone,and the salts examined were K_2HPO_4,Na_2cO_3,K_2cO_3,(NH_4)_2sO_4,NaHPO_4,K_3PO_4 and c_6H_5NaO_*** optimal extraction system consisted of 34 wt%K_3PO_4,28 wt% ethanol,and 38 wt% fermentation broth containing 23.0 g·L^(-1)1,3-propanediol,which gave the highest partition coefficient of 33 and recovery yield of 97%.The results demonstrated that salting-out extraction was a promising method for 1,3-propanediol recovery from fermentation broth.

关键词： Fermentation Downstream process 1 3-Propanediol clostridium beijerinckii Liquid-liquid extraction salting-out extraction

-765G > c cOX-2 polymorphism may be a susceptibility marker for gastric adenocarcinoma in patients with atrophy or intestinal metaplasia

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第34期12卷 5473-5478页

作者： carina pereira Hugo sousa Paula Ferreira Maria Fragoso luís Moreira-Dias carlos Lopes Rui Medeiros Mário Dinis-Ribeiro Molecular Oncology Group Portuguese Institute of Oncology of Porto Portugal and IcBAs Abel Salazar Institute for the Biomedical Sciences Porto Portugal Oncology Department Portuguese Institute of Oncology of Porto Portugal Gastroenterology Department Portuguese Institute of Oncology of Porto Portugal and cintesis / Faculty of Medicine University of Porto Porto Portugal

AIM： To investigate the relationship between the -765G 〉 c cOX-2 polymorphism and the development of different gastric lesions： atrophy or intestinal metaplasia and gastric adenocarcinoma. METHODs： A cross-sectional study was performed involving 320 Portuguese individuals （210 without evidence of neoplastic disease, 73 patients with gastric adenocarcinomas and 37 with atrophy or intestinal metaplasia） using a PcR-RFLP method.REsULTs： -765c allele was overrepresented in the patients with gastric adenocarcinoma （51%） when compared either with the control group （38%） or patients with atrophy or intestinal metaplasia （27%）. callele was found to be very common in our population （0.22）, and a multivariate logistic regression analysis revealed nearly 3-fold increased risk for the progression to gastric adenocarcinoma in patients with atrophy or intestinal metaplasia carrying the -765c allele （OR = 2.67, 95% cI = 1.03-6.93; P = 0.04）.cONclusION： -765c carrier status should be considered as another susceptibility marker for gastric adenocarcinoma development in patients with atrophy or intestinal metaplasia.

关键词： Gastric adenocarcinoma Atrophy Intestinal metaplasia cOX-2 Polymorphism PcR-RFLP Pharmacogenomic

Ultrastructural analysis of the loss of desiccation tolerance in germinating Eremanthus erythropappus seeds

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Forestry Research 2019年第4期30卷 1331-1336页

作者： Rayana s.Martins Anderson c.José José Marcio R.Faria Wilson V.s.pereira Department of Forest sciences Federal University of Lavras(UFLA)

Eremanthus erythropappus(Dc.)MacLeish is an important forest species native to the Brazilian savanna biome,an environment with well-defined rainy and dry *** seeds are desiccation tolerant,non-dormant and dispersed at the end of dry *** exposes them to the first sporadic rains that can trigger germination but the subsequent dry days can compromise survival of the newly germinated *** study evaluates if the damages caused by drying of germinating *** seeds,at the stage when they have lost desiccation tolerance,are *** percentage of normal seedlings was evaluated when seeds with different imbibition times were dried to their initial water content and then pre-humidified and *** tolerance was fully lost after 0.5 mm of hypocotyl-radicle protrusion(approximately 72 h)when the radicle had root hairs,a possible indicator of sensitivity to *** of cell contents and ultrastructural damage to the seeds subjected to drying were observed by electron scanning *** hairs disappeared after drying,reappearing after pre-humidification,possibly an attempt to increase the surface area of the radicle for water ***,the hypocotylradicle axis became darkened,probably by antioxidant system failure,causing seed death.

关键词： candeia Drying Desiccation tolerant seeds Rehydration scanning electron microscopy

Oxidative stability of green weakfish(cynoscion virescens)by-product surimi and surimi gel enhanced with a spondias mombin *** phenolic-rich extract during cold storage

在线全文

学校读者我要写书评

暂无评论

Food Bioscience 2022年第6期50卷 1260-1267页

作者： Thamyres césar de Albuquerque sousa Edson luís Lima silva Valquiria cardoso da silva Ferreira Marta suely Madruga Fábio Anderson pereira da silva Postgraduate Program in Agrifood Technology Center for HumanSocial and Agrarian SciencesFederal University of ParaíbaBananeirasParaíba58220-000Brazil center for Human Social and Agrarian SciencesFederal University of ParaíbaBananeirasParaíba58220-000Brazil Postgraduate Program in Food science and Technology Technology CenterFederal University of ParaíbaJardim Cidade UniversitáriaJoão PessoaParaíba58900-000Brazil

The aim of this investigation was to assess the effect of yellow mombin bagasse extract(YMBE),alone or combined with commercial cryoprotectants,on the quality changes during cold storage of surimi and surimi gel prepared with the cutting by-product of green weakfish(cynoscion virescens).Four treatments were elaborated:sc(surimi control),sE(surimi with addition of 1%extract),scP(surimi with the addition of 4%sorbitol+4%sucrose)and sEcP(surimi with addition of 1%extract+4%sorbitol+4%sucrose).The addition of the extract was effective in maintaining the whiteness of the surimi and its gel throughout *** the end of 12 days of cold storage,the surimi gel prepared with sE treatment presented high whiteness compared to the control *** inclusion of 1%YMBE in isolation or combined with commercial cryoprotectants showed a positive effect on the inhibition of lipid and protein oxidation of *** conclusion,YMBE extract is a promising alternative to be used as a natural food preservative in surimi and surimi gel.

关键词： Natural antioxidant cryoprotectants Gelification Oxidation surimi

Performance of evolutionary optimized machine learning for modeling total organic carbon in core samples of shale gas fields

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum 2024年第1期10卷 150-164页

作者： Leonardo Goliatt c.M.saporetti L.c.Oliveira E.pereira Department of computational and Applied Mechanics Federal University of Juiz de ForaJuiz de ForaBrazil Department of computational Modeling Polytechnic InstituteRio de Janeiro State UniversityNova FriburgoBrazil Petrobras Rio de JaneiroBrazil Department of stratigraphy and Paleontology Rio de Janeiro State UniversityRio de JaneiroBrazil

Rock samples'TOc content is the best indicator of the organic matter in source *** origin rock samples’analysis is used to calculate it manually by *** method requires time and resources because it relies on samples from many well intervals in source ***,research has been done to aid this *** learning algorithms can estimate total organic carbon instead of well logs and stratigraphic *** light of these efforts,the current work present a study on automating the total organic carbon estimation using machine learning approaches improved by an evolutionary methodology to give the model flexibility and *** algorithms,differential evolution,particle swarm optimization,grey wolf optimization,artificial bee colony,and evolution strategies were used to improve machine learning models to predict *** six metaheuristics were integrated into four machine learning methods:extreme learning machine,elastic net linear model,linear support vector regression,and multivariate adaptive regression *** samples from the YuDong-Nan shale gas field,located in the sichuan basin,were used to evaluate the hybrid *** findings show that combining machine learning models with an evolutionary algorithms in a hybrid fashion produce flexible models that accurately predict *** results show that,independent of the metaheuristic used to guide the model selection,optimized extreme learning machines attained the best performance scores according to six *** hybrid models can be used in exploratory geological research,particularly for unconventional oil and gas resources.

关键词： Total organic carbon Hybrid models Automated machine learning Evolutionary algorithms Geology

The inception of a Paleotethyan magmatic arc in Iberia

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2015年第2期6卷 297-306页

作者： M.F.pereira A.castro c.Fernández IDL Departamento de Geociências ECT Universidade de évora Departamento de Geología Universidad de Huelva Departamento de Geodinámica y Paleontología Universidad de Huelva

This paper presents a compilation of recent U-Pb （zircon） ages of late carboniferous-early Permian （Lc EP） calc-alkaline batholiths from lberia, together with a petrogenetic interpretation of magma generation based on comparisons with Mesozoic and Tertiary cordilleran batholiths and experimental melts. Zircon U-Pb ages distributed over the range ca. 315-280 Ma, indicate a linkage between calc-alkaline magmatism, Iberian orocline generation and Paleotethys subduction. It is also shown that Iberian Lc-EP calcalkaline batholiths present unequivocal subduction-related features comparable with typical cordilleran batholiths of the Pacific Americas active margin, although geochemical features were partially obscured by local modifications of magmas at the level of emplacement by country rock assimilation. When and how Lc-EP calc-alkaline batholiths formed in Iberia is then discussed, and a new and somewhat controversial interpretation for their sources and tectonic setting （plume-assisted relamination） is suggested. The batholiths are proposed to have formed during the subduction of the Paleotethys oceanic plate （Pangaea self-subduction） and, consequently, they are unrelated to Variscan collision. The origin of the Iberian batholiths is related to the Eurasian active margin and probably represents the inception of a Paleotethvan arc in the core of Pangaea.

关键词： Permo-carboniferous calc-alkaline arc-related batholiths Pangaea Paleotethys subduction Variscan and cimmerian cycles