检索结果-南通市图书馆

PREDICTION OF VORTEX-INDUCED VIBRATION OF LONG FLEXIBLE CYLINDERS MODELED BY A COUPLED NONLINEAR OSCILLATOR:INTEGRAL TRANSFORM SOLUTION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2012年第6期24卷 888-898页

作者： GU Ji-jun AN Chen LEVI Carlos SU Jian Ocean Engineering Program COPPEUniversidade Federal do Rio de Janeiro Nuclear Engineering Program COPPEUniversidade Federal do Rio de Janeiro

The Generalized Integral Transform Technique （GITT） was applied to predict dynamic response of Vortex-Induced Vibration （VIV） of a long flexible cylinder. A nonlinear wake oscillator model was used to represent the cross-flow force acting on the cylinder, leading to a coupled system of second-order Partial Differential Equations （PDEs） in temporal variable. The GITT approach was used to transform the system of PDEs to a system of Ordinary Differential Equations （ODEs）, which was numerically solved by using the Adams-Moulton and Gear method （DIVPAG） developed by the International Mathematics and Statistics Library （IMSL）. Numerical results were presented for comparison to those given by the finite difference method and experimental results, allowing a critical evaluation of the technique performance. The influence of variation of mean axial tension induced by elongation of flexible cylinder was evaluated, which was shown to be not negligible in numerical simulation of VIV of a long flexible cylinder.

关键词： Vortex-Induced Vibration (VIV) nonlinear wake oscillator flexible cylinder integral transform

Andean orogenic signature in the Quaternary sandy barriers of Southernmost Brazilian Passive Margin – Paradigm as a source area

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2021年第4期12卷 61-70页

作者： Farid Chemale Junior Ernesto Luiz Correa Lavina Julierme Justin Carassai Tiago Jonatan Girelli Cristiano Lana Programa de Pós Graduação em Geologia Universidade do Vale do Rio dos Sinos93022-220São LeopoldoRSBrazil Departamento de Geologia Universidade Federal do Ouro Preto35400-000Morro do CruzeiroOuro PretoMGBrazil

Multiple source provenance of sediments and submarine fan formation are herein investigated based on Quaternary sandy barriers of the Brazilian Southernmost Coastal ***-ICP-MS dating on 1625 detrital zircons from marine and aeolian facies sands of four successive lagoon-barrier systems are *** characterization of Archean to Pleistocene zircons into a younger Andean(22±4 Ma to 1±1 Ma,48 from 1625),Mesozoic to Paleozoic,and Mesoproterozoic(479 from 1622)populations suggest that the main feeding of sediments to the coastal plain occurred through the La Plata River drainage *** significant contribution of sediments is transported from the mouth of La Plata River northward by longshore circulation(littoral drift).Minor contributions are also recognized as.a farther source associatedwith the Patagonia drainage and nearby source related to the Uruguay/Rio Grande do Sul Shield and the ParanáBasin,drained by the Camaquãand Jacuí*** latter one is recognized by the contribution fromNeoproterozoic to Early Paleozoic,and some Paleoproterozoic and Archean zircon *** definition of the sources of clastic sediments allows inferences about the origination of Rio Grande Fan where both the cold Falkland and the warm Brazil currents played a major role.

关键词： U–Pb zircon Coastal plain Andean provenance Source to sink process Rio Grande Fan Ocean Atlantic

Effect of proteases on water-soluble and fat-soluble aroma precursors of goat visceras protein hydrolysate

在线全文

学校读者我要写书评

暂无评论

Food Bioscience 2022年第3期47卷 975-985页

作者： Ana Rita Ribeiro de Araújo Cordeiro Lorena Lucena de Medeiros Lary de Souza Olegário Leila Moreira de Carvalho Taliana Kenia Alencar Bezerra Maria Teresa Bertoldo Pacheco Mércia de Sousa Galvão Marta Suely Madruga Post Graduate Program in Food Science and Technology Department of Food EngineeringTechnology CentreFederal University of ParaibaCampus I58051-900João PessoaParaíbaBrazil Food Technology Institute (ITAL).Science and Food Quality Center 13070-179CampinasSão PauloBrazil

This study investigated the action of proteolytic enzymes in the production of goat viscera hydrolysates,and their flavoring *** study focus the production of flavor precursor molecules and the formation of volatile compounds resulting from four hydrolysis treatments:HA-Alcalase®,HF-Flavourzyme®,HN-Neutrase®,and HFN-Flavourzyme® and Neutrase®.The highest degree of hydrolysis (26.74%),number (23 volatiles) and concentration of volatile compounds (274.0 μg/L) were obtained with the action of *** main classes of volatile compounds identified in hydrolysates included acids,aldehydes,pyrazines,terpenes and Streacker *** acids,sugars and fatty acids were identified with higher concentrations in HF and HFN hydrolysates due to the low participation of these precursors in the formation of volatile ***,the use of Alcalase in the proteolysis of goat viscera stood out compared to other enzymes,providing impacting aroma compounds,such as pyrazines,for meat flavor.

关键词： Aroma precursors Flavoring Goat byproducts Proteases Enzymatic hydrolysates Volatile compounds

Atacama Field Campaign: laboratory and in-situ measurements for remote sensing applications

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

International Journal of Digital Earth 2019年第1期12卷 43-61页

作者： Cristian Mattar Andrés Santamaría-Artigas Flavio Ponzoni Cibele T.Pinto Carolina Barrientos Glynn Hulley Laboratory for Analysis of the Biosphere(LAB) University of ChileSantiagoChile Department of Geographical Sciences University of MarylandCollege ParkMDUSA Divisão de Sensoriamento Remoto(DSR) Instituto Nacional de Pesquisas Espaciais(INPE)São PauloBrasil Aerial Photogrammetric Service(SAF) Chilean Air ForceSantiagoChile Jet Propulsion Laboratory(JPL) California Institute of TechnologyPasadenaCAUSA

This work presents the preliminary results of the first field calibration campaign performed in the Atacama Desert,Chile,between the 18 and 22 August 2014,called the Atacama Field Campaign(ATAFIC 2014).In situ measurements were performed in order to spectrally characterize the surface reflectance spectra between 0.3 and 2.5μm,radiometric temperature(8.0–14.0μm)and atmospheric measurements.A soil sample was collected and analyzed using Fourier Transform Infrared Spectroscopy and X-Ray Diffraction techniques to characterize the surface reflectance spectra and mineralogical composition,*** land surface emissivity in addition to GOES,MODIS and Landsat-8 land surface temperature(LST)were also *** showed that the spectral features of the Atacama soil and the characteristics of this geographical zone,which is featured as the most hyper-arid and cloudless place in the world,make this area a potential target for surface reflectance *** and night LST comparison between field and remote sensing data are lower than 2 K and the Root Mean Square Error for land surface emissivity is close to 2%.This work opens the possibilities to consider the Atacama Desert as a reference target for calibration and validation activities for earth observation missions’purposes.

关键词： Atacama spectroradiometry emissivity temperature surface reflectance

3D printed millireactors for process intensification

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

Chinese Journal of Chemical Engineering 2020年第1期28卷 180-190页

作者： Harrson S.Santana Alan C.Rodrigues Mariana G.M.Lopes Felipe N.Russo Joao L.Silva Jr Osvaldir P.Taranto School of Chemical Engineering University of CampinasBrazil Federal Institute of Education Science and Technology of South of Minas GeraisBrazil

The scope of the present research aims at demonstrating the 3D printing use in the manufacturing of microchannels for chemical process applications. A comparison among digital model processing applications for 3D print(slicers) and a print layer thickness analysis were performed. The 3D print fidelity was verified in several devices, including the microchannels’ printing with and without micromixer zones. In order to highlight the 3D print potential in Chemical Engineering, the biodiesel synthesis was also carried out in a millireactor manufactured by 3D printing. The millireactor operated under laminar flow regime with a total flow rate of 75.25 ml·min^-1(increment of about 130 times over traditional microdevices used for biodiesel production).The printed millireactor provided a maximum yield of Ethyl Esters of 73.51% at 40 ℃, ethanol:oil molar ratio of7 and catalyst concentration of 1.25 wt% and residence time about 10 s. As a result of flow rate increment attained in the millireactor, the number of required units for scaling-up the chemical processes is reduced. Using the approach described in the present research, anyone could produce their own millireactor for chemical process in a simple way with the aid of a 3D printer.

关键词： Process intensification 3D printer Millireactors Micromixers Microdevices Biodiesel

Asymmetric hydrogenation and transfer hydrogenation in the enantioselective synthesis of flavonoids

在线全文

学校读者我要写书评

暂无评论

Organic Chemistry Frontiers 2022年第4期9卷 1165-1194页

作者： Guilherme S.Caleffi Felipe C.Demidoff Carmen Najera Paulo R.R.Costa Laboratorio de Quimica Bioorganica(LQB) Instituto de Pesquisas de Produtos NaturaisUniversidade Federal do Rio de JaneiroAv.Carlos Chagas Filho 373Bloco HCidade Universitaria21941-902 Rio de Janeiro Centro de Innovacion en Quimica Avanzada(ORFEO-CINQA) Universidad de AlicanteApdo.99E-03080 AlicanteSpain

Asymmetric hydrogenation(AH)and asymmetric transfer hydrogenation(ATH)are versatile synthetic methodologies widely employed in the preparation of chiral *** this review,we explore the applications of AH and ATH in the total synthesis of natural flavonoids and their analogues,highlighting the limitations and opportunities in the field.

关键词： compounds field hydrogenation

Studying Formability Limits By Combining Conventional and Incremental Sheet Forming Process

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

Chinese Journal of Mechanical Engineering 2021年第4期34卷 78-89页

作者： Fabio Andre Lora Daniel Fritzen Ricardo Alves de Sousa Lirio Schaffer Department of Materials Engineering Federal University of Recôncavo da BahiaCampus CETENSFeira de SantanaBahia 44085-132Brazil SATC Uni-versity CriciumaBrazil Center of Mechanical Technology and Automation Department of Mechanical EngineeringUniversity of Aveiro3810-193 AveiroPortugal Federal University of Rio Grande do Sul Porto AlegreBrazil

In this work it is assessed the potential of combining conventional and incremental sheet forming processes in a same sheet of *** so-called hybrid forming approach is performed through the manufacture of a pre-forming by conventional forming,followed by incremental sheet *** main objective is analyzing strain *** pre-forming induced in the conventional forming stage will determine the strain paths,directly influencing the strains produced by the incremental *** conduct the study,in the conventional processes,strains were imposed in three different ways with distinct true *** the incremental stage,the pyramid strategy was adopted with different wall *** the experiments,the true strains and the final geometries were *** simulation was also employed for the sake of comparison and correlation with the measured *** could be observed that single-stretch pre-strain was directly proportional to the maximum incremental strains achieved,whereas samples subjected to biaxial pre-strain influenced the formability according to the degree of pre-strain ***-strain driven by the prior deep-drawing operation did not result,in this particular geometry,in increased formability.

关键词： Hybrid forming process Incremental sheet forming Strain paths Numerical simulation

Taxifolin stability: In silico prediction and in vitro degradation with HPLC-UV/UPLCe ESI-MS monitoring

在线全文

学校读者我要写书评

暂无评论

Journal of Pharmaceutical Analysis 2021年第2期11卷 232-240页

作者： Fernanda Cristina Stenger Moura Carmem Lúciados Santos Machado Favero Reisdorfer Paula Angelica Garcia Couto Maurizio Ricci Valdir Cechinel-Filho Tiago J.Bonomini Louis P.Sandjo Tania Mari Belle Bresolin Pharmaceutical Sciences Graduate Program School of Health SciencesCourse of PharmacyUniversidade do Vale do ItajaíItajaíSC88302-202Brazil Laboratory of Research and Development of Drugs Pharmaceutical Sciences Graduate ProgramSchool of Health SciencesCourse of PharmacyUniversidade Federal do PampaUruguaianaRS97500-970Brazil Department of Pharmaceutical Science Universita degli Studi di PerugiaPerugiaPG06123Italy Chemistry Department Universidade Federal de Santa CatarinaTrindadeFlorian opolisSC88040-900Brazil

Taxifolin has a plethora of therapeutic activities and is currently isolated from the stem bark of the tree Larix gmelinni(Dahurian larch). It is a flavonoid of high commercial interest for its use in supplements or in antioxidant-rich functional foods. However, its poor stability and low bioavailability hinder the use of flavonoid in nutritional or pharmaceutical formulations. In this work, taxifolin isolated from the seeds of Mimusops balata, was evaluated by in silico stability prediction studies and in vitro forced degradation studies(acid and alkaline hydrolysis, oxidation, visible/UV radiation, dry/humid heating) monitored by high performance liquid chromatography with ultraviolet detection(HPLC-UV) and ultrahigh performance liquid chromatography-electrospray ionization-mass spectrometry(UPLC-ESI-MS). The in silico stability prediction studies indicated the most susceptible regions in the molecule to nucleophilic and electrophilic attacks, as well as the sites susceptible to oxidation. The in vitro forced degradation tests were in agreement with the in silico stability prediction, indicating that taxifolin is extremely unstable(class 1) under alkaline hydrolysis. In addition, taxifolin thermal degradation was increased by *** the other hand, with respect to photosensitivity, taxifolin can be classified as class 4(stable).Moreover, the alkaline degradation products were characterized by UPLC-ESI-MS/MS as dimers of taxifolin. These results enabled an understanding of the intrinsic lability of taxifolin, contributing to the development of stability-indicating methods, and of appropriate drug release systems, with the aims of preserving its stability and improving its bioavailability.

关键词： Dihydroquercetin In silico stability prediction Forced degradation

Timing of Proterozoic magmatism in the Sunsas belt, Bolivian Precambrian Shield, SW Amazonian Craton

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2021年第6期12卷 277-293页

作者： Ingrid M.Nedel Reinhardt A.Fuck Amarildo S.Ruiz Gerardo R.Matos-Salinas Alanielson da C.D.Ferreira Instituto de Geociências Universidade de Brasília(UnB)Brasília-DFBrazil Faculdade de Geociências Universidade Federal de Mato GrossoCuiabá-MTBrazil Instituto de Investigaciones Geológicas y del Medio Ambiente Universidad Mayor de San Andrés(UMSA)Pabellón GeologíaCalle 27Campus Universitario Cota CotaLa PazBolivia Department of Earth Sciences Stellenbosch UniversityPrivate Bag X1Matieland7602 StellenboschSouth Africa

We present new U–Pb zircon and monazite ages from the Sunsas belt granitic magmatism in Bolivia, SW Amazonian Craton. The geochronological results revealed four major magmatic events recorded along the Sunsas belt domains. The older igneous event formed a granitic basement coeval to the Rio Apa Terrane(1.95–1.85 Ga) in the southern domain. The second magmatic episode is represented by 1.68 Ga granites associated to the Paraguá Terrane(1.69–1.66 Ga) in the northern domain. The 1.37–1.34 Ga granites related to San Ignacio orogeny represent the third and more pervasive magmatic event, recorded throughout the Sunsas belt. Moreover, magmatic ages of ~1.42 Ga revealed that the granitogenesis associated to the Santa Helena orogeny also affected the Sunsas belt, indicating that it was not restricted to the Jauru Terrane. Lastly, the 1.10–1.04 Ga youngest magmatism was developed during the Sunsas orogeny and represents the final magmatic evolution related to Rodinia assembly. Likewise, the 1.95–1.85 and 1.68 Ga inherited zircon cores obtained in the ~1.3 Ga and 1.0 Ga granite samples suggest strong partial melting of the Paleoproterozoic sources. The 1079 ± 14 Ma and 1018 ± 6 Ma monazite crystallization ages can be correlated to the collisional tectono-thermal event of the Sunsas orogeny, associated to reactions of medium-to high-grade metamorphism. Thus, the Sunsas belt was built by heterogeneous 1.95–1.85 Ga and 1.68 Ga crustal fragments that were reworked at 1.37–1.34 Ga and 1.10–1.04 Ga related to orogenic collages. Furthermore, the 1.01 Ga monazite age suggests that granites previously dated by zircon can bear evidence of a younger thermal history. Therefore, the geochronological evolution of the Sunsas belt may have been more complex than previously thought.

关键词： SW Amazonian Craton Sunsas belt U–Pb geochronology Zircon Monazite