检索结果-南通市图书馆

on the analytical solution of transient friction in channel flows

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1447-1466页

作者： F.J.garc.a-garc.a P.FARINAS-ALVARINo department of Naval&Industrial Engineering Polytechnic School of EngineeringUniversity of A CorunaCampus Industrial de FerrolFerrol 15403A CorunaSpain Integraciones Técnicas de Seguridad S.A.Pol.Ind.Espiritu SantoC/Nobel15Cambre 15650A CorunaSpain

The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULF)and the purely turbulent component(PTC),and the contributions are analyzed separately by theoretical *** is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state *** universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is *** is shown that the time constant is related to the turbulence's frozen ***,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.

关键词： transient friction transient flow unsteady channel flow

Radiative loss of coherence in free electrons:a long-range quantum phenomenon

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第2期13卷 294-301页

作者： Cruz I.Velasco Valerio Di Giulio F.Javier garc.a de Abajo ICFo-Institut de Ciencies Fotoniques The Barcelona Institute of Science and Technology08860Castelldefels(Barcelona)Spain ICREA-InstitucióCatalana de Recerca i Estudis Avançats Passeig Lluís Companys 2308010BarcelonaSpain

Quantum physics rules the dynamics of small objects as they interact over microscopic length ***,quantum correlations involving macroscopic distances can be observed between entangled photons as well as in atomic gases and matter waves at low *** long-range nature of the electromagnetic coupling between charged particles and extended objects could also trigger quantum phenomena over large ***,we reveal a manifestation of quantum mechanics that involves macroscopic distances and results in a nearly complete depletion of coherence associated with which-way free-electron interference produced by electron-radiation coupling in the presence of distant extended *** is a ubiquitous effect that we illustrate through a rigorous theoretical analysis of a two-path electron beam interacting with a semi-infinite metallic plate and find the inter-path coherence to vanish proportionally to the path separation at zero temperature and exponentially at finite *** investigated regime of large distances originates in the coupling of the electron to radiative modes assisted by diffraction at material structures but without any involvement of material *** the fundamental interest of this macroscopic quantum phenomenon,our results suggest an approach to measuring the vacuum temperature and nondestructively sensing the presence of distant objects.

关键词： temperature quantum macroscopic

Correcting distortions of thin-walled machined parts by machine hammer peening

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 Aeronautics 2024年第6期37卷 439-453页

作者： Aitor MADARIAGA Mikel CUESTA Gorka oRTIZ-de-ZARATE Eneko saenz-de-ARGANDoNA denis SoRIANo Michael B.PRIME Pedro Jose ARRAZoLA department of Materials University of ManchesterOxford RoadManchester M139PLUnited Kingdom Mechanical and Industrial Production department Faculty of EngineeringMondragon UnibertsitateaArrasate 20500Spain Los Alamos National Laboratory Los AlamosNew MexicoUSA

Thin-walled aerostructural components frequently get distorted after the machining *** to correct distortions or eventually rejecting parts significantly increases the *** paper proposes a new approach to correct distortions in thin-walled components by strategically applying hammer peening on target surfaces of a machined *** alloy 7475-T7351 was chosen for this *** study was divided in two ***,the residual stresses(RS)induced by four different pneumatic hammer peening conditions(modifying the stepover distance and initial offset)were characterised in a test coupon,and one of the conditions was selected for the next *** the second stage,a FEM model was used to predict distortions caused by machining in a representative ***,the RS induced by hammer peening were included in an FEM model to define two hammer peening strategies(varying the coverage area)to analyse the capability to reduce *** workpieces were machined and then treated with the simulated hammer peening strategies for experimental *** in the test coupon showed that pneumatic hammer peening can generate high compressive RS(-50 to350 MPa)up to 800 lm depth,with their magnitude increasing with a reduced stepover *** of hammer peening over 4% of the surface of the representative workpiece reduced the machininginduced distortions by 37%,and a coverage area of 100% led to and overcorrection by a factor of *** confirms that hammer peening can be strategically applied(in target areas and changing the percentage of coverage)to correct low or severe distortions.

关键词： Aeronautics Machining,Hammer Peening Aluminium alloy Distortions Residual Stress

Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2024年第2期15卷 189-199页

作者： Juan A.garc.a-Armenteros Center for Advanced Studies in Earth Sciences Energy and Environment(CEACTEMA)University of Jaén23071 JaenSpain

This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geological Survey’s storage *** analyses based on quality indicators obtained using TEQC have been carried *** guidelines and data quality information from the IGS stations have been considered as the quality references,with the stations ALJI,EPCU,and TIoU standing out as the worst stations,while on the contrary,FUEN,PALM,PILA,and TRIA meet the quality requirements to become an IGS *** relationship between the GPS data quality and their GAMIT-and Gipsy X-derived postfit ionosphere-free phase residuals has also been investigated,and the results reveal an inversely proportional *** has been found that the stations showing an increase in elevation of the horizon line,also show an increase in cycle slips and multipath,are among the poorest quality stations,and among those with the highest postfit RMS of phase ***,the evolution of the vegetation around the antenna should be considered as it could cause a progressive loss of quality,which is not complying with the IGS *** quality assessment shows that the Topo-Iberia stations are appropriate for geodetic purposes,but permanent monitoring would be necessary to avoid the least possible loss of data and *** addition,a method to characterize the GNSS data quality is proposed.

关键词： GPS dataquality's effects IGS quality standard Postfit LC phase residual Qualityassessment Topo-Iberia CGPS network

Co oxidation under lean and stoichiometric conditions over ceriazirconia with very low metal contents(Cu,Co,Ag and Pt)

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第9期42卷 1669-1681,I0002页

作者： J.C.Martínez-Munuera M.P.Yeste A.garc.a-garc.a MCMA Group Department of Inorganic Chemistry and Institute of MaterialsUniversity of AlicanteCarretera de San Vicente del Raspeig s/n03690San Vicente del RaspeigAlicanteSpain Solid Chemistry and Catalysis Group Department of Materials ScienceMetallurgic Engineering and Inorganic ChemistryInstitute of Electronic Microscopy and Materials ResearchUniversity of CádizAp.40E-11510Puerto RealCádizSpain

In this work,several ceria-zirconia based catalysts with very lo w(and equimolar) metal contents were prepared,characterised and tested for the Co oxidatio n reaction(under lean and stoichiometric conditions),trying to emulate those conditions found in a diesel oxidation catalyst(DoC) system from a diesel engine and those encountered under gasoline exhaust(λ=1).The metals chosen are Cu,Co,Ag and Pt(as a reliable benchmark).The results reveal enormous differences among reducibility and catalytic activity despite quite similar structural and textural properties of the catalysts,showing differences among dispersion(Ag-catalyst seems to present a low level of dispersion).This catalyst seems to be characterised,as well,by a strong electronic interaction between Ce and Ag centres which is suggested to yield an improved reducibility under H_(2)-TPR ***,the order in catalytic activity(Cu>Ag>Co≈Pt>>support) seems not to follow the order found in reducibility and the Cu-catalyst seems to be the most active independently on the reaction conditions,yielding nearly overlapped Co oxidation catalytic *** restingly,a stro ng correlation between the catalytic activity under the two conditions tested and the oSC values of the Ce_(0.8)Zr_(0.2)o_(2)-supported metal catalysts is ***,oSC parameter measured at 150℃ can be used as a relevant descriptor to evaluate the Co oxidation activity at low and medium conversions for the investigated catalysts,much better than the H_(2)-TPR measurements.

关键词： Co oxidation Low metal content Ceria-zirconia Copper species oSC parameter Rare earths

Comparing Fine-Tuning, Zero and Few-Shot Strategies with Large Language Models in Hate Speech detection in English

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第9期140卷 2849-2868页

作者： Ronghao Pan JoséAntonio garc.a-Díaz Rafael Valencia-garc.a departamento de Informática y Sistemas Universidad de MurciaCampus de EspinardoMurcia30100Spain

Large Language Models(LLMs)are increasingly demonstrating their ability to understand natural language and solve complex tasks,especially through text *** of the relevant capabilities is contextual learning,which involves the ability to receive instructions in natural language or task demonstrations to generate expected outputs for test instances without the need for additional training or gradient *** recent years,the popularity of social networking has provided a medium through which some users can engage in offensive and harmful online *** this study,we investigate the ability of different LLMs,ranging from zero-shot and few-shot learning to *** experiments show that LLMs can identify sexist and hateful online texts using zero-shot and few-shot approaches through information ***,it is found that the encoder-decoder model called Zephyr achieves the best results with the fine-tuning approach,scoring 86.811%on the Explainable detection of online Sexism(EDoS)test-set and 57.453%on the Multilingual detection of Hate Speech Against Immigrants and Women in Twitter(HatEval)***,it is confirmed that the evaluated models perform well in hate text detection,as they beat the best result in the HatEval task *** error analysis shows that contextual learning had difficulty distinguishing between types of hate speech and figurative ***,the fine-tuned approach tends to produce many false positives.

关键词： Hate speech detection zero-shot few-shot fine-tuning natural language processing

Global paleobiogeography of Albian—Cenomanian(mid-Cretaceous)marine ostracods

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 Palaeogeography 2024年第2期13卷 212-236页

作者： Bernardo Vázquez-garc.a Jorge Villegas-Martín Gerson Fauth Leonardo Borghi Aristóteles de Moraes Rios Netto Post-Graduate Program in Geology Unisinos UniversitySao LeopoldoRSBrazil Technological Institute of Paleoceanography and Climate Change-Itt oceaneon Unisinos UniversitySao LeopoldoRSBrazil Laboratory of Sedimentary Geology(Lagesed) Department of GeologyInstitute of GeosciencesUFRJ-Federal Universityof Riode JaneiroBrazil Labmicro Department of GeologyInstitute of GeosciencesUFRJ-Federal University of Rio de JaneiroBrazil

despite their potential for providing important information for paleobiogeography,studies using ostracod assemblages compiled from global datasets have been scarce so *** this study,the paleogeographic implications of the relationship between different ostracod assemblages are analyzed and discussed for the Albian and *** compiled an ostracod dataset at the genus level,with 168 genera for the Albian and 174 for the Cenomanian,to which different multivariate statistical methods of grouping were *** affinity between different ostracod assemblages from different regions allowed for the delineation of 30 operational geographic units(oGUs)for the Albian,and 32 oGUs for the Cenomanian,grouped in three paleobiogeographic units(PBUs;Megatethys,Persia,and Austral)and one sub-unit(PBSU;Maghreb associated to the Megatethys).The Maghreb PBSU showed minor changes between the Albian and *** relationship among the oGUs grouped in each PBU is related to different factors,such as eustatic sea level events,similar climatic zones,and marine current circulation patterns.A relationship was observed between the Gabon and Nigeria oGUs with the Persia PBU,which suggests a direct east—west connection between them during the *** affinity observed in the Austral PBU between the South American,South African,and Australian regions during the Albian can be explained by their relative geographic isolation due to the Walvis Ridge *** eventual flooding of this barrier led to the relationship observed between the SE Brazilian and Bolivian regions with the Austral ***,the data also suggested that the separation of the Indian subcontinent from the Austral PBU took place during the Cenomanian.

关键词： operational geographic units Paleobiogeographic units Albian Cenomanian Marine ostracods

Emerging role of liquid biopsy in rat sarcoma virus mutated metastatic colorectal cancer:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal oncology 2024年第1期16卷 234-243页

作者： João Gramaça Isabel Gomes Fernandes Carolina Trabulo Joana Gonçalves Rita Gameiro dos Santos Adriano Baptista Idília Pina Centro Hospitalar Barreiro Montijo Centro Hospitalar Barreiro MontijoSetúbalBarreiro 2830-003Portugal Medical oncology Unit Centro Hospitalar Barreiro MontijoSetúbalBarreiro 2830-003Portugal

BACKGRoUND In patients with metastatic colorectal cancer(mCRC),the treatment options are limited and have been proved to be affected by rat sarcoma virus(RAS)mutational *** RAS wild-type(wt)patients,the combination of antiepidermal growth factor receptor(EGFR)monoclonal antibodies with chemotherapy(CT)is more effective than CT *** the other hand,RAS-mutated patients are not eligible for treatment with anti-EGFR *** SUMMARY Eleven patients with initially RAS-mutated mCRC were followed from diagnosis to May *** the time of cell-free DNA determination,five patients had undergone one CT line,five patients had undergone two CT lines,and one patient had undergone three CT lines(all in combination with bevacizumab).At the second and third treatment lines[second line(2L),third line(3L)],patients with neo-RAS wt received a combination of CT and *** neo-RAS wt patients treated with anti-EGFR,our findings indicated an increase in progression-free survival for both 2L and 3L(14.5 mo,P=0.119 and 3.9 mo,P=0.882,respectively).Regarding 2L overall survival,we registered a slight increase in neo-RAS wt patients treated with anti-EGFR(33.6 mo vs 32.4 mo,P=0.385).At data cut-off,two patients were still alive:A RAS-mutated patient undergoing 3L treatment and a neo-RAS wt patient who received 2L treatment with anti-EGFR(ongoing).CoNCLUSIoN our case series demonstrated that monitoring RAS mutations in mCRC by liquid biopsy may provide an additional treatment line for neo-RAS wt patients.

关键词： Metastatic colorectal cancer Rat sarcoma virus mutational status Liquid biopsy Rat sarcoma virus wild-type Neo-rat sarcoma virus wild-type Anti-epidermal growth factor receptor therapy Case report

online demand Response Characterization Based on Variability in Customer Behavior

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 Modern Power Systems and Clean Energy 2024年第3期12卷 936-946页

作者： Lester Marrero Daniel Sbárbaro Luis garc.a-Santander the department of Electrical Engineering University of ConcepciónConcepción 4070409Chile

This paper proposes an online framework to characterize demand response(DR)over *** proposed framework facilitates obtaining and updating the daily consumption patterns of *** essential concept of response profile class(RPC)is introduced for characterization and complemented by the measure of the variability in customer *** paper uses a modified version of the incremental clustering by fast search and find of density peaks(CFSFDP)algorithm for daily profiles,considering the multivariate normal kernel density estimator and incremental forms of the Davies-Bouldin(i DB)and Xie-Beni(i XB)validity *** studies conducted using real-world and simulated daily profiles of residential and commercial Chilean end-users have demonstrated how the proposed framework can continuously characterize *** proposed framework is proven to achieve realistic customer models for effective energy management by estimating the customer response to price signals at the distribution system operator(DSo)level.

关键词： demand response(DR) incremental indice online characterization online clustering response profile class(RPC)