检索结果-南通市图书馆

Mathematical modeling of tornadoes and squall storms

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2011年第2期2卷 215-221页

作者： sergey A.Arsen'yev Laboratory of Geomechanics Department of the Earth and Planetary PhysicsThe Schmidt's Institute of the Earth's PhysicsRussian Academy of Sciences(RAS)Bolshaya Gruzinskaya Street10GSP-5123995 Moscow D-242Russia

Recent advances in modeling of tornadoes and twisters consist of significant achievements in mathematical calculation of occurrence and evolution of a violent F5-class tornado on the Fujita scale, and four-dimensional mathematical modeling of a tornado with the fourth coordinate time multiplied by its characteristic velocity. such a tornado can arise in a thunderstorm supercell filled with turbulent whirlwinds. A theory of the squall storms is proposed. The squall storm is modeled by running pertur- bation of the temperature inversion on the lower boundary of cloudiness. This perturbation is induced by the action of strong, hurricane winds in the upper and middle troposphere, and looks like a running solitary wave （soliton）; which is developed also in a field of pressure and velocity of a wind. If a soliton of a squall storm gets into the thunderstorm supercell then this soliton is captured by supercell. It leads to additional pressure fall of air inside a storm supercell and stimulate amplification of wind velocity here. As a result, a cyclostrophic balance inside a storm supercell generates a tornado. Comparison of the radial distribution of wind velocity inside a tornado calculated by using the new formulas and equations with radar observations of the wind velocity inside Texas Tornado Dummit in 1995 and inside the 3 May 1999 Oklahoma City Tornado shows good correspondence.

关键词： Tornadoes squall storm Atmosphere boundarylayer Mathematical modeling

Thermodynamics of Phase Equilibria in FeO-TiO2-Al_(2)O_(3)system

在线全文

学校读者我要写书评

暂无评论

China's Refractories 2022年第2期31卷 40-44页

作者： Oksana M.BORYsENKO sergey M.LOGVINKOV Galina M.sHABANOVA Andrii A.IVAsHURA Alla M.KOROHODsKA Kharkiv Polytechnic Institute National Technical UniversityKharkiv 61002Ukraine

This scientific paper discusses the information on the structure of the three-component system FeO-TiO_(2)-Al_(2)O_(3),which is necessary for the creation of heat-resistant oxide *** structure of binary systems:FeO-Al_(2)O_(3),FeO-TiO_(2),and Al_(2)O_(3)-TiO_(2)is described,and the data on the FeO-TiO_(2)-Al_(2)O_(3)system are *** thermodynamic data of all compounds of the system are given,on the basis of which the change in the Gibbs free energy in the temperature range of 800-1900 K for twenty-one exchange reactions was *** has been established that the triangulation of the FeO-TiO_(2)-Al_(2)O_(3)system changes in five temperature ranges:up to 1408 K(TiO_(2)exists in the polymorphic modification-anatase),1408-1537 K(TiO_(2)exists in the polymorphic modification-rutile and pseudobrookite is stable),1537-1630 K(thialite is stable),1630-2076 K(rearrangement cannot occur)and above 2076 K(the presence of the stoichiometric compound Al_(4)TiO_(8)is allowed).Two-phase equilibria up to 1408 K are stable:Al_(2)O_(3)-FeTiO_(3),FeTiO_(3)-FeAl_(2)O_(4),and FeAl_(2)O_(4)-Fe_(2)TiO_(4);in the temperature range of 1408-1537 K:FeAl_(2)O_(4)-TiO_(2),FeAl_(2)O_(4)-FeTi_(2)O_(5),FeAl_(2)O_(4)-FeTiO_(3),and FeAl_(2)O_(4)-Fe_(2)TiO_(4);in the temperature range of 1537-1630 K:FeAl_(2)O_(4)-TiO_(2),FeAl_(2)O_(4)-FeTi_(2)O_(5),FeAl_(2)O_(4)-FeTiO_(3),FeAl_(2)O_(4)-Fe_(2)TiO_(4),and FeAl_(2)O_(4)-Al_(2)TiO_(5);in the temperature range of 1630-2076 K:FeTi_(2)O_(5)-Al_(2)TiO_(5),Al_(2)TiO_(5)-FeTiO_(3),FeTiO_(3)-Al_(2)O_(3),FeTiO_(3)-FeAl_(2)O_(4),and FeAl_(2)O_(4)-Fe_(2)TiO_(4);over 2076 K:FeTi_(2)O_(5)-Al_(2)TiO_(5),FeTi_(2)O_(5)-Al_(4)TiO_(8),Al_(4)TiO_(8)-FeTiO_(3),Al_(4)TiO_(8)-Fe_(2)TiO_(4),Al_(4)TiO_(8)-FeO,and Al_(4)TiO_(8)-FeAl_(2)O_(4).

关键词： phase equilibria change in Gibbs free energy triangulation hercynite ulvospinel ilmenite pseudobrookite thialite

Hidden stage of intracranial hemorrhage in newborn rats studied with laser speckle contrast imaging and wavelets

在线全文

学校读者我要写书评

暂无评论

Journal of Innovative Optical Health sciences 2015年第5期8卷 99-106页

作者： Alexey N.Pavlov Arkady s.Abdurashitov Olga N.Pavlova Valery V.Tuchin Olga s.sindeeva sergey s.sindeev Oxana V.semyachkina-Glushkovskaya Department of Physics Saratov State University 83 Astrakhanskaya Str.Saratov 410012Russia Department of Biology Saratov State University 83 Astrakhanskaya Str.Saratov 410012Russia

Using the laser speckle contrast imaging and wavelet-based analyses,we investigate a latent("hidden")stage of the development of intracranial hemorrhages(ICHs)in newborn *** apply two measures based on the continuous wavelet-transform of blood flow velocity in the sagittal sinus,namely,the spectral energy in distinct frequency ranges and a multiscality degree characterizing complexity of experimental *** show that the wavelet-based multifractal formalism reveals changes in the cerebrovascular blood flow at the development of ICH.

关键词： Cerebral blood flow laser speckle contrast imaging stress wavelet-analysis complexity

strain control of layer-resolved negative capacitance in superlattices

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

npj Computational Materials 2020年第1期6卷 127-130页

作者： Raymond Walter sergey Prosandeev Charles Paillard L.Bellaiche Department of Physics and Institute for Nanoscience and Engineering University of ArkansasFayettevilleAR 72701USA Department of Mathematical sciences University of ArkansasFayettevilleAR 72701USA Identity Engineering Kinesso LLCConwayAR 72032USA Institute of Physics and Physics Department of southern Federal University Rostov-na-Donu 344090Russia Laboratoire structures Propriétés et Modélisation des SolidesCentraleSupélecUMR CNRS 8580UniversitéParis-Saclay91190 Gif-sur-YvetteFrance

Negative capacitance in BaTiO_(3)/srTiO_(3) superlattices is investigated by Monte Carlo simulations in an atomistic effective Hamiltonian model,using fluctuation formulas for responses to the local macroscopic field that incorporates depolarizing *** show that epitaxial strain can tune the negative capacitance of the BaTiO_(3) ferroelectric layer and the overall capacitance of the *** addition,we predict and explain an original switching of the negative capacitance from the BaTiO3 layer to the srTiO_(3) layer at low temperatures for intermediate strains.

关键词： capacitance layer resolved

Limb Muscle Hemodynamics and Arterial Distensibility Depend on Atmospheric Pressure in Hypertensive Men

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Biomedical and Environmental sciences 2013年第4期26卷 284-294页

作者： Vladimir N.MELNIKOV sergey G.KRIVOsCHEKOV Tamara G.KOMLYAGINA svetlana Y.RECHKINA Nathan s.CONsEDINE Institute of Physiology Siberian Branch of the Russian Academy of Medical SciencesNovosibirsk630117Russia sanatorium "El'tsovka " NovosibirskRussia Department of Psychological Medicine University of AucklandNew Zealand

Objective To verify whether peripheral blood circulation and arterial wall distensibility are influenced by atmospheric pressure （AtPr） and to examine if their association is dependent on age and/or sex. Methods Associations among natural AtPr levels （on the examination day as well as 1 and 2 days prior）, limb muscle hemodynamics, and distensibility of conduit arteries were retrospectively examined in an observational study of 276 untreated patients with primary moderate hypertension （mean age 56.4 years, 194 men）. Forearm and calf circulations at rest and 3 min after ischemia were measured by venous occlusion plethysmography. Compliance of the brachial and shank arteries was assessed by oscillometry. Results After adjustment for age, degree of hypertension, and season, correlation and multiple resression analyses revealed a season-independent but age-dependent direct correlation between the stiffness of limb arteries and AtPr levels on the examination day in men, but not women. The association weakened with the degree of hypertension, disappeared with age, and was more evident in the arms than in the legs. Conclusion Parameters of arterial wall distensibility in adult hypertensive men are susceptible to AtPr changes within the usually observed limits （730-770 mmHg）. It is proposed that reduction of arterial wall barometric responsiveness in women and aging men is a likely mechanism underlying their meteosensitivity.

关键词： Atmospheric pressure Arterial stiffness Compliance Venous circulation Age-dependence sex difference season

Evolution of permafrost in China during the last 20 ka

在线全文

学校读者我要写书评

暂无评论

science China Earth sciences 2019年第8期62卷 1207-1223页

作者： Huijun JIN Xiaoying JIN Ruixia HE Dongliang LUO Xiaoli CHANG shaoling WANG sergey s MARCHENKO sizhong YANG Chaolu YI shijie LI stuart A HARRIs Northeast China Observational station of Cold-regions Engineering and Environment State Key Laboratory of Frozen Soils EngineeringNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China school of Civil Engineering Harbin Institute of TechnologyHarbin150090China school of Resources and Environment University of Chinese Academy of ScienceBeijing100049China Hunan University of science and Technology Xiangtan411201China Permafrost Laboratory Geophysical InstituteUniversity of Alaska FairbanksFairbanksAK99775USA GFZ German Research Centre for Geosciences TelegrafenbergPotsdam D-14473Germany Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing100010China Institute of Geochemistry Chinese Academy of SciencesGuiyang550081China Department of Geography University of CalgaryCalgaryAlberta T2N1N4Canada

The formation and evolution of permafrost in China during the last 20 ka were reconstructed on the basis of large amount of paleo-permafrost remains and paleo-periglacial evidence, as well as paleo-glacial landforms, paleo-flora and paleofauna records. The results indicate that, during the local Last Glacial Maximum(LLGM) or local Last Permafrost Maximum(LLPMax), the extent of permafrost of China reached 5.3×106-5.4×106 km2, or thrice that of today, but permafrost shrank to only0.80×106-0.85×106 km2, or 50% that of present, during the local Holocene Megathermal Period(LHMP), or the local Last Permafrost Minimum(LLPMin). On the basis of the dating of periglacial remains and their distributive features, the extent of permafrost in China was delineated for the two periods of LLGM(LLPMax) and LHMP(LLPMin), and the evolution of permafrost in China was divided into seven periods as follows:(1) LLGM in Late Pleistocene(ca. 20000 to 13000-10800 a BP)with extensive evidence for the presence of intensive ice-wedge expansion for outlining its LLPMax extent;(2) A period of dramatically changing climate during the early Holocene(10800 to 8500-7000 a BP) when permafrost remained relatively stable but with a general trend of shrinking areal extent;(3) The LHMP in the Mid-Holocene(8500-7000 to 4000-3000 a BP)when permafrost degraded intensively and extensively, and shrank to the LLPMin;(4) Neoglaciation during the late Holocene(4000-3000 to 1000 a BP, when permafrost again expanded;(5) Medieval Warming Period(MWP) in the late Holocene(1000-500 a BP) when permafrost was in a relative decline;(6) Little Ice Age(LIA) in the late Holocene(500-100 a BP), when permafrost relatively expanded, and;(7) Recent warming(during the 20 th century), when permafrost continuously degraded and still is degrading. The paleo-climate, geography and paleopermafrost extents and other features were reconstructed for each of these seven periods.

关键词： Permafrost evolution Cryogenic wedge structures Local Last Glacial Maximum(LLGM) Local Holocene Megathermal Period(LHMP) China

Investigation of radio pulsar emission features using power spectra

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2018年第8期18卷 63-70页

作者： Valery M.Malofeev sergey A.Tyul'bashev EN.Lebedev Physical Institute of the Russian Academy of sciences V.V.Vitkevich Pushchino Radio Astronomy ObservatoryPRAO ASC FIANPushchinoRussia

since 2013, round-the-clock monitoring of the sky has been carried out simultaneously in 96 beams using a high-sensitivity radio telescope called the Large Phased Array （LPA） at the frequency 110.25 MHz. These observations are made under the program of interplanetary plasma investigation. The same data are used to search for pulsars by means of power spectra. To increase the sensitivity of the pulsar search, 500-600 power spectra corresponding to different days of observations are summed. In the integrated spectra of known pulsars, besides expected improvement in signal-to-noise （s/N） ratio for the frequency harmonics, some features are explored in this paper. We present the 27 strongest pulsars which are in a field with declination 21° - 42°. The observable details in the integrated power spectra are connected with the presence of pulsar periods of the second （P2） and third （P3） class, which have been identified. Empirical relations for calculating these periods are obtained. The value P2 is estimated for 26 pulsars, and for 15 sources it is made for the first time. The value P3 is estimated for 13 pulsars, among them these values are given for five sources for the first time.

关键词： pulsars general - pulsars

K^+ retention in leaf mesophyll, an overlooked component of salinity tolerance mechanism:A case study for barley

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2015年第2期57卷 171-185页

作者： Honghong Wu Min Zhu Lana shabala Meixue Zhou sergey shabala school of Land and Food University of Tasmania

Plant salinity tolerance is a physiologically complex trait, with numerous mechanisms contributing to it. In this work, we show that the ability of leaf mesophyll to retain K＋ represents an important and essentially overlooked component of a salinity tolerance mechanism. The strong positive correlation between mesophyll K＋ retention ability under saline conditions （quantified by the magnitude of NaCl-induced K＋ efflux from mesophyll） and the overall salinity tolerance （relative fresh weight and/or survival or damage under salinity stress） was found while screening 46 barley （Hordeum vulgare L.） genotypes contrasting in their salinity tolerance. Genotypes with intrinsically higher leaf K＋ content under control conditions were found to possess better K＋ retention ability under salinity and, hence, overall higher tolerance. Contrary to previous reports for barley roots, K＋ retention in mesophyll was not associated with an increased H＋-pumping in tolerant varieties but instead correlated negatively with this trait. These findings are explained by the fact that increased H＋ extrusion may be needed to charge balance the activity and provide the driving force for the high affinity HAK/KUP K＋ transporters required to restore cytosolic K＋ homeostasis in salt-sensitive genotypes.

关键词： Cytosolic K+ homeostasis ion flux membrane potential membrane transport tissue tolerance

Ultrafast Optomechanical Terahertz Modulators Based on stretchable Carbon Nanotube Thin Films

在线全文

学校读者我要写书评

暂无评论

Ultrafast science 2023年第6期3卷 1-9页

作者： Maksim I.Paukov Vladimir V.starchenko Dmitry V.Krasnikov Gennady A.Komandin Yuriy G.Gladush sergey s.Zhukov Boris P.Gorshunov Albert G.Nasibulin Aleksey V.Arsenin Valentyn s.Volkov Maria G.Burdanova Center for Photonics and 2D Materials Moscow Institute of Physics and TechnologyDolgoprudny.Russia skolkovo Institute of science and Technology MoscowRussia Prokhorov General Physics Institute of the Russian Academy of sciences MoscowRussia Laboratory of Advanced Functional Materials Yerevan State UniversityYerevanArmenia Institute of solid state Physics of the Russian Academy of sciences ChernogolovkaRussia.

For terahertz wave applications,tunable and rapid modulation is highly *** studied by means of optical pump-terahertz probe spectroscopy,single-walled carbon nanotube(sWCNT)thin films demonstrated ultrafast carrier recombination lifetimes with a high relative change in the signal under optical excitation,making them promising candidates for high-speed ***,combination of sWCNT thin films and stretchable substrates facilitated studies of the sWCNT mechanical properties under strain and enabled the development of a new type of an optomechanical *** applying a certain strain to the sWCNT films,the effective sheet conductance and therefore modulation depth can be fine-tuned to optimize the designed *** exhibited a photoconductivity change of approximately 2 times of magnitude under the strain because of the structural modification in the sWCNT *** was used to control the terahertz signal with a modulation depth of around 100%without strain and 65%at a high strain operation of 40%.The sensitivity of modulators to beam polarization is also shown,which might also come in handy for the design of a stretchable *** results give a fundamental grounding for the design of high-sensitivity stretchable devices based on sWCNT films.

关键词： strain excitation films