检索结果-南通市图书馆

Journal of Oceanology and Limnology 2022年第2期40卷 703-711页

作者： Fernando gÓMEZ Department of Biological and Environmental Sciences and Technologies University of SalentoLecce 73100Italy

Three species of dinophysoid planktonic dinoflagellates are described from the eastern Mediterranean *** *** was collected at 70-m depth in the Ionian *** small species showed a more asymmetric midbody and a proportionally longer neck when compared to the closer relative *** individuals of Dinofurcula tricornuta *** at 154-m depth in the Marmara Sea are characterized by three posterior-oriented processes when compared to its congeneric *** is the first record of the genus Dinofurcula beyond the eastern tropical Pacific *** profunda *** at 500-m depth in the Ionian Sea is characterized by ovate hypotheca and a serrate crest-like left sulcal list when compared to its close relative *** findings evidence an undescribed biodiversity in the under-sampled subphotic depths.

关键词： deep ocean Dinophyta Dinoflagellata Mediterranean Sea mesopelagic new species

The turbidite-contourite-tidalite-baroclinite-hybridite problem: orthodoxy vs. empirical evidence behind the “Bouma Sequence”

在线全文

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2021年第2期10卷 125-156页

作者： g.Shanmugam Department of Earth and Environmental Sciences The University of Texas at ArlingtonTX 76019USA

The underpinning problems of deep-water facies still remain unresolved.(1) The Tb, Tc, and Td divisions of the turbidite facies model, with traction structures, are an integral part of the "Bouma Sequence"(Ta, Tb, Tc, Td, Te).However, deposits of thermohaline contour currents, wind-driven bottom currents, deep-marine tidal currents, and baroclinic currents(internal waves and tides) also develop discrete rippled units, mimicking Tc.(2) The application of "cut-out" logic of sequences, which was originally introduced for the "Bouma Sequence", with sharp basal contacts and sandy divisions containing well-developed traction structures, to muddy contorts with gradational basal contacts and an absence of well-developed traction structures is incongruent.(3) The presence of five internal divisions and hiatus in the muddy contoured facies model is in dispute.(4) Intersection of along slope contour currents with down slope sediment-gravity flows, triggering hybrid flows, also develops traction structures.(5) The comparison of genuine hybrid flows with down slope flow transformation of gravity flows is inconsistent with etymology of the term "hybrid".(6) A reexamination of the Annot Sandstone at the Peira Cava type locality in SE France fails to validate either the orthodoxy of five internal divisions of the "Bouma Sequence" or their origin by turbidity currents. For example, the "Ta" division is composed of amalgamated units with inverse grading and floating mudstone clasts, suggesting a mass-transport deposit(MTD). The "Tb" and "Tc" divisions are composed of double mud layers and sigmoidal cross bedding, respectively, which suggest a tidalite origin.(7) Although it was reasonable to introduce a simplistic "Bouma Sequence" in 1962, at a time of limited knowledge on deep-water processes, it is obsolete now in 2021 to apply this model to the rock record amid a wealth of new knowledge.(8)The disconnect between 12 observed, but questionable, modern turbidity currents and over 10,

关键词： Turbidity currents Contour currents Tidal currents Internal waves and tides Hybrid flows The Bouma Sequence BCRS(i.e. bottom-current reworked sands)

The effectiveness of eyespots and masquerade in protecting artificial prey across ontogenetic and seasonal shifts

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2022年第4期68卷 451-458页

作者： Elizabeth g Postema Department of Entomology and Nematology University of CaliforniaDavisCA 95616USA

When constraints on antipredator coloration shift over the course of development,it can be advantageous for animals to adopt different color strategies for each life *** caterpillars in the genus Papilio exhibit unique ontogenetic color sequences:for example,early instars that masquerade as bird feces,with later instars possessing eyespots.I hypothesize that larvae abandon feces masquerade in favor of eyespots due to ontogenetic changes in signaler *** ontogenetic pattern also occurs within broader seasonal shifts in background color and predator activity.I conducted predation experiments with artificial prey to determine how potential signaling constraints(specifically size and season)shape predation risk,and consequently the expression of ontogenetic color change in Papilio ***,both predation and background greenness declined significantly from July to September,though there was little evidence that these patterns impacted the effectiveness of either color *** size and color strongly affected the attack rate of avian predators:attacks increased with prey size regardless of color,and eyespotted prey were attacked more than masquerading prey *** results may reflect a key size-mediated tradeoff between conspicuousness and intimidation in eyespotted prey,and raise questions about how interwoven aspects of behavior and signal environment might maintain the prevalence of large,eyespotted larvae in nature.

关键词： ontogenetic color change eyespots masquerade predator-prey dynamics season

Luminescence enhancement of rare earth ions by metal nanostructures

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 Rare Earths 2009年第4期27卷 641-645页

作者： g.A.Denisenko A.V.Shubnikov Institute of Crystallography Russian Academy of Sciences D.V.Skobeltsyn Institute of Nuclear Physics of Moscow State University

Well-ordered metal structures, i.e. arrays of nanosized tips on silver surface for studies of the luminescence enhancement of absorbed media with rare earth ions were used. These arrays were prepared by the metal evaporation on track membranes. Calculations of reso- nanee frequencies of tips regarded as semispheroids were done taking into account the interaction between dipoles of tips. They were used to discuss experimental results for media with Eu（NO3）3·6H2O salt basing on data for bulk silver dielectric function.

关键词： rare earth ions silver nanosized tips luminescence enhancement

An Analytical Study on the Synchronization of Murali-Lakshmanan-Chua Circuits

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2015年第1期32卷 22-26页

作者： g.Sivaganesh Alagappa Chettiar College of Engineering and Technology

An explicit analytical solution is presented for unidirectionally coupled two Murali-Lakshmanan-Chua circuits exhibiting chaos synchronization in their dynamics. The transition of the system from an unsynchronized state to a state of complete synchronization under the influence of the coupling parameter is observed through phase portraits obtained from the analytical solutions of the circuit equations characterizing the system.

关键词： An Analytical Study on the Synchronization of Murali-Lakshmanan-Chua Circuits

Modeling the impact of climate change on sediment transport and morphology in coupled watershed-coast systems:A case study using an integrated approach

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2014年第3期29卷 304-315页

作者： Achilleas g.SAMARAS Christopher g KOUTITAS Research Fellow CIRI-ECFluid Dynamics Research UnitUniversity of BolognaVia del Lazzaretto 15/5Bologna 40131Italy Department of Civil Engineering Aristotle University of ThessalonikiUniversity Campus

Climate change is an issue of major concern *** impact on the natural and human environment is studied intensively,as the expected shift in climate will be significant in the next few *** experience shows that the effects will be critical in coastal areas,resulting in erosion and inundation phenomena *** addition to that,coastal areas are subject to "pressures" from upstream watersheds in terms of water quality and sediment *** present paper studies the impact of climate change on sediment transport and morphology in the aforementioned coupled *** study regards a sandy coast and its upstream watershed in Chalkidiki,North greece;it is based on:(a)an integrated approach for the quantitative correlation of the two through numerical modeling,developed by the authors,and(b)a calibrated application of the relevant models Soil and Water Assessment Tool(SWAT)and PELNCON-M,applied to the watershed and the coastal zone,*** examined climate change scenarios focus on a shift of the rainfall distribution towards fewer and more extreme rainfall events,and an increased frequency of occurrence of extreme wave *** indicate the significance of climatic pressures in wide-scale sediment dynamics,and are deemed to provide a useful perspective for researchers and policy planners involved in the study of coastal morphology evolution in a changing climate.

关键词： Climate change Sediment transport Coastal morphology Integrated approach Numerical modeling

A study on the seismic behavior of a retrofitted building based on nonlinear static and dynamic analyses

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2005年第1期4卷 173-180页

作者： Esra Mete güneyisi gülay Altay Department of Civil Engineering Bo■azi■i University Bebek ■stanbul TurkeyResearchAssistantDepartment of Civil Engineering Bo■azi■i University Bebek ■stanbul Turkey Professor

This study describes the seismic performance of an existing five storey reinforced concrete building which represents the typical properties of low-rise non-ductile buildings in Turkey. The effectiveness of shear walls and the steel bracings in retrofitting the building was examined through nonlinear static and dynamic analyses. By using the nonlinear static analysis, retrofitted buildings seismic performances under lateral seismic load were compared with each other. Moreover, the performance points and response levels of the existing and retrofitting cases were determined by way of the capacity-spectrum method described in ATC-40 (1996). For the nonlinear dynamic analysis the records were selected to represent wide ranges of duration and frequency content. Considering the change in the stiffness and the energy dissipation capacities, the performance of the existing and retrofitted buildings were evaluated in terms of story drifts and damage states. It was found that each earthquake record exhibited its own peculiarities, dictated by frequency content, duration, sequence of peaks and their amplitude. The seismic performance of retrofitted buildings resulted in lower displacements and higher energy dissipation capacity depending mainly on the properties of the ground motions and the retrofitting strategies. Moreover, severe structural damage (irreparable or collapse) was observed for the existing building. However, buildings with retrofit alternatives exhibited lower damage levels changing from no damage to irreparable damage states.

关键词： nonlinear static analysis nonlinear time history analysis performance level retrofitting shear wall steel bracing

Uniform and L-convergence of Logarithmic Means of Walsh-Fourier Series

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2006年第2期22卷 497-506页

作者： g.gáT U.gOgINAVA Institute of Mathematics and Computer Science College of Nyiregyhaza Department of Mechanics and Mathematics Tbilisi State University

The （NSrlund） logarithmic means of the Fourier series of the integrable function f is：1/lnn-1∑k=1Sk（f）/n-k, where ln：=n-1∑k=11/k.In this paper we discuss some convergence and divergence properties of this logarithmic means of the Walsh-Fourier series of functions in the uniform, and in the L^1 Lebesgue norm. Among others, as an application of our divergence results we give a negative answer to a question of Móricz concerning the convergence of logarithmic means in norm.

关键词： Walsh system Norlund logarithmic means Convergence divergence properties

Cold Cracking of Flux Cored Arc Welded Armour grade High Strength Steel Weldments

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2009年第4期25卷 516-526页

作者： g.Magudeeswaran V.Balasubramanian g.Madhusudhan Reddy Metal Joining Research Center(MJRC) Sri Ramakrishna Engineering College Centre for Materials Joining & Research(CEMAJOR) Department of Manufacturing EngineeringAnnamalai University Metal Joining Section Defence Metallurgical Research Laboratory(DMRL)

In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered （Q＆.T） steel welds. Flux cored arc welding （FCAW） process were used making welds using austenitic stainless steel （ASS） and low hydrogen ferritic steel （LHF） consumables. The diffusible hydrogen levels in the weld metal of the ASS and LHF consumables were determined by mercury method. Residual stresses were evaluated using X-ray stress analyzer and implant test was carried out to study the cold cracking of the welds. Results indicate that ASS welds offer a greater resistance to cold cracking of armour grade Q＆T steel welds.

关键词： Quenched and tempered steel Flux cored arc welding process Weld cold cracking Implant testing

Algorithms for automatic measurement of SIS-type hysteretic underdamped Josephson junction’s parameters by current-voltage characteristics

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2023年第4期21卷 60-74页

作者： Aleksey g.Vostretsov Svetlana g.Filatova Laboratory of Quantum Cryogenic Electronics Novosibirsk State Technical UniversityNovosibirsk630073Russia Chinakal Institute of Mining Siberian BranchRussian Academy of SciencesNovosibirsk630091Russia

Some electrical parameters of the SIS-type hysteretic underdamped Josephson junction(JJ)can be measured by its current-voltage characteristics(IVCs).Currents and voltages at JJ are commensurate with the intrinsic noise level of measuring *** leads to the need for multiple measurements with subsequent statistical *** this paper,the digital algorithms are proposed for the automatic measurement of the JJ parameters by *** algorithms make it possible to implement multiple measurements and check these JJ parameters in an automatic mode with the required *** complete sufficient statistics are used to minimize the root-mean-square error of parameter measurement.A sequence of current pulses with slow rising and falling edges is used to drive JJ,and synchronous current and voltage readings at JJ are used to realize measurement *** algorithm performance is estimated through computer *** significant advantage of the proposed algorithms is the independence from current source noise and intrinsic noise of current and voltage meters,as well as the simple implementation in automatic digital measuring *** proposed algorithms can be used to control JJ parameters during mass production of superconducting integrated circuits,which will improve the production efficiency and product quality.

关键词： Algorithm design and analysis Critical current Current-voltage characteristics(IVCs) Josephson junction(JJ) Measurement errors Parameter estimation