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Anatomy of a eustatic event during the Turonian (Late Cretaceous) hot greenhouse climate

Science China Earth Sciences 2017年第1期60卷 20-29页

作者： Bilal u. HAQ Brian T. HuBER Department of Paleobiology MRC-121Smithsonian InstitutionWashington D C 20013USA Sorbonne ISTEP Pierre&Marie Curie UniversityParis 75005France

Sequence stratigraphic studies consider relative change in sea level(as regulated by eustasy,local tectonics and sediment supply)as the main builder of the stratigraphic *** has generally been considered as a consequence of the growth and decay of continental ice sheets that would explain large,rapid changes in sea level,even during periods of relative global climatic ***,such a mechanism has become increasingly difficult to envision during times of extreme global warmth such as the Turonian,when the equator-to-pole temperature gradient was very low and the presence of polar ice seems *** paper investigates the timing and extent of sea level falls during the late Cenomanian through Turonian,especially the largest of those events,sequence boundary KTu4,which occurred during the middle to late Turonian peak of the Cretaceous hot greenhouse *** conclude that the amplitude of the widespread third-order sea level fall in the middle Turonian that is centered at^91.8 Ma varies at different locations depending on the influence of dynamic topography on local tectonics and regional climatic *** volume variations seem unlikely as a mechanism for controlling sea level at this ***,this causal factor cannot be ruled out completely since Antarctic highlands(if they existed in the Late Cretaceous)could sequester enough water as ice to cause eustatic *** ascertain this requires detailed tomographic imaging of Antarctica,followed by geodynamic modeling,to determine whether high plateaus could have existed to accumulate ephemeral ice *** mechanisms for sea level change,such as transference between ground water(a small amplitude shorter time scale effect)and the ocean and entrainment and release of water from the mantle to the oceanic reservoir(a potentially large amplitude and longer time scale process),are intriguing and need to be explored further to prove their efficacy at third-order time scales.

关键词： Eustatic event Turonian Hot greenhouse climate

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Instantaneous frequency and wave mode identification in a magnetosheath using few spatial points

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Chinese Physics B 2013年第8期22卷 496-501页

作者： Nathaniel E u Beloff N George N J Department of Physics Akwa Ibom State UniversityNigeria university of Sussex Brighton UK

Observational data such as those obtained from the magnetosheath in the downstream of Earth＇s bow shock have waveforms that differ from those of sinusoidal signals. In practice, they are not even aggregates of sinusoidal signals. Therefore, the frequency decomposition for the data requires technique that will account for the time-varying features of the data that will lead to deduction of physical meaning of the observations. The combination of empirical mode decompo- sition （EMD） and Hilbert transform has been used for extracting the various contributing oscillatory modes （EMDs） and the instantaneous frequency determination （Hilbert transform） of every physically meaningful mode called intrinsic mode func- tion （IMF）. The resulting instantaneous frequencies are used to determine instantaneous wave vectors. The combination of the instantaneous frequencies and wave vectors is useful in the identification of wave modes based on the characteristics of the waves. The results show that EMD-Hilbert can be more reliable than simple Hilbert transform alone.

关键词： EMD-Hilbert transform instantaneous frequency and wave vector

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Effect of benzaldehyde on the electrodeposition and corrosion properties of Ni–W alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1060-1066页

作者： u.Pramod Kumar C.Joseph Kennady Department of Chemistry Karunya Institute of Technology and SciencesKarunya NagarCoimbatore 641114Tamil NaduIndia

The effect of different concentrations of benzaldehyde on the electrodeposition of Ni–W alloy coatings on a mild steel substrate from a citrate electrolyte was investigated in this study. The electrolytic alkaline bath(p H 8.0) contained stoichiometric amounts of nickel sulfate, sodium tungstate, and trisodium citrate as precursors. The corrosion resistance of the Ni–W-alloy-coated specimens in 0.2 mol/L H2SO4 was studied using various electrochemical techniques. Tafel polarization studies reveal that the alloy coatings obtained from the bath containing 50 ppm benzaldehyde exhibit a protection efficiency of 95.33%. The corrosion rate also decreases by 21.5 times compared with that of the blank. A higher charge-transfer resistance of 1159.40 ?·cm2 and a lower double-layer capacitance of 29.4 μF·cm-2 further confirm the better corrosion resistance of the alloy coating. X-ray diffraction studies reveal that the deposits on the mild steel surface are consisted of nanocrystals. A lower surface roughness value(Rmax) of the deposits is confirmed by atomic force microscopy.

关键词： nickel–tungsten alloys benzaldehyde electrodeposit

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Nanofillers modification of Epocast 50-A1/946 epoxy for bonded joints

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Chinese Journal of Aeronautics 2014年第5期27卷 1288-1300页

作者： u.A.Khashaba A.A.Aljinaidi M.A.Hamed Department of Mechanical Engineering Faculty of Engineering King Abdulaziz University

Epocast 50-A1/946 epoxy was primarily developed for joining and repairing of composite aircraft structural components. The objective of the present work is to modify the Epocast epoxy resin by different nanofillers infusion. The used nanofillers include multi-walled carbon nanotubes（MWCNTs）, SiC and Al2O3 nanoparticles. The nanofillers with different weight percentages are ultrasonically dispersed in the epoxy resin. The sonication time and amplitude for MWCNTs are reduced compared to Al2O3 and SiC nanoparticles to avoid the damage of MWCNTs during sonication processes. The fabricated neat epoxy and twelve nanocomposite panels were characterized via standard tension and in-plane shear tests. The experimental results show that the nanocomposites materials with 0.5wt% MWCNTs, 1.5wt% SiC and 1.5wt% Al2O3 nanoparticles have the highest improvement in the tensile properties compared to the other nanofiller loading *** improvements in the shear properties of these nanocomposite materials were respectively equal to 5.5%, 4.9%, and 6.3% for shear strengths, and 10.3%, 16.0%, and 8.1% for shear moduli. The optimum nanofiller loading percentages will be used in the following papers concerning their effect on the bonded joints/repairs of carbon fiber reinforced composites.

关键词： Iosipescu shear tests Nanocomposites Optimum nanofiller weight percentage Scanning electron microscopic Tension tests ultrasonic

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Effects of slag fineness on durability of mortars

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2007年第11期8卷 1725-1730页

作者： TOPu lker Bekir BLR Turhan Department of Civil Engineering Eski■ehir Osmangazi university Eski■ehir 26480 Turkey

In recent years, the usages of by-products and wastes in industry have become more important. The importance of the sustainable development is also of increasing. The utilizations of wastes, as mineral admixture or fine aggregate, reduce the consumption of the natural resources and improve the durability of concrete. In this study, the effect of the fineness on the high temperature and sulphate resistances of concrete mortar specimens, produced with ground granulated blast-furnace slag (GBFS) replacing cement, is investigated. The compressive and flexural strength test results for all series related to durability effects, exposing temperature and solutions, exposure times for these durability effects, slag content and fineness are discussed. Conse- quently, the optimum slag contents are determined for producing the sulphate and high temperature resistant mortars.

关键词： Cement Fineness Ground slag High temperature effect Sulphate attack Sustainable development

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Modulation of lysophosphatidic acid (LPA) receptor activity: the key to successful neural regeneration?

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Neural Regeneration Research 2020年第1期15卷 53-54页

作者： Isabel Gross Anja u.Brauer Research Group Anatomy School for Medicine and Health ScienceCarl von Ossietzky University OldenburgOldenburgGermany Research Center for Neurosensory Science Carl von Ossietzky University OldenburgOldenburgGermany

The central nervous system(CNS)is characterized by a remarkably elaborate cellular architecture comprising large numbers of glial and neuronal cells with enormous functional diversity,organized into highly complex and specific *** development,the various neural cell types must first be correctly specified,then assume their appropriate positions through carefully choreographed cellular migration,and finally establish and refine their functional connections,often over long *** end result of all these processes is an extraordinarily intricate anatomical structure,able to receive,integrate,and store information and orchestrate appropriate responses.

关键词： neural specified finally

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Variational data encoding and correlations in quantum-enhanced machine learning

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Chinese Physics B 2024年第9期33卷 298-306页

作者： Ming-Hao Wang Hua L¨u School of Physics Hubei UniversityWuhan 430062China School of Science Hubei University of TechnologyWuhan 430068China

Leveraging the extraordinary phenomena of quantum superposition and quantum correlation,quantum computing offers unprecedented potential for addressing challenges beyond the reach of classical *** paper tackles two pivotal challenges in the realm of quantum computing:firstly,the development of an effective encoding protocol for translating classical data into quantum states,a critical step for any quantum *** encoding strategies can significantly influence quantum computer ***,we address the need to counteract the inevitable noise that can hinder quantum *** primary contribution is the introduction of a novel variational data encoding method,grounded in quantum regression algorithm *** adapting the learning concept from machine learning,we render data encoding a learnable *** allowed us to study the role of quantum correlation in data *** numerical simulations of various regression tasks,we demonstrate the efficacy of our variational data encoding,particularly post-learning from instructional ***,we delve into the role of quantum correlation in enhancing task performance,especially in noisy *** findings underscore the critical role of quantum correlation in not only bolstering performance but also in mitigating noise interference,thus advancing the frontier of quantum computing.

关键词： quantum machine learning variational data encoding quantum correlation

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Saddle Point Criteria in Nonsmooth Semi-Infinite Minimax Fractional Programming Problems

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Journal of Systems Science & Complexity 2018年第2期31卷 446-462页

作者： MISHRA S K SINGH Yadvendra VERMA R u Department of Mathematics Banaras Hindu University Varanasi-221005 India. Department of Mathematics Texas State University USA

This paper considers a nonsmooth semi-infinite minimax fractional programming problem（SIMFP） involving locally Lipschitz invex functions. The authors establish necessary optimality conditions for SIMFP. The authors establish the relationship between an optimal solution of SIMFP and saddle point of scalar Lagrange function for SIMFP. Further, the authors study saddle point criteria of a vector Lagrange function defined for SIMFP.

关键词： Generalized convexity Lagrange function nonsmooth programming problems saddlepoint semi-infinite minimax fractional programming problems.

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Improved hybrid position/force controller design of a flexible robot manipulator using a sliding observer

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Journal of Systems Engineering and Electronics 2009年第1期20卷 146-158页

作者： Farooq M Wang Daobo Dar N. u Coll. of Automation Engineering Nanjing Univ. of Aeronautics & Astronautics Nanjing 210016 P. R. China Coll. of Mechanical Engineering Univ. of Engineering and Technology Taxila Pakistan

An improved hybrid position/force controller design of a flexible robot manipulator is presented using a sliding observer. The friction between the end effector and the environment is considered and compensated. For systematic reasons the controller is designed taking into consideration the rigid link subsystems and the flexible joints. The proposed control system satisfies the stability of the two subsystems and copes with the uncertainty of robot dynamics. A sliding observer is designed to estimate the time derivative of the torque applied as input to the rigid part of the robot. For the stability of the observer, it is assumed that the uncertainty of the observed system is bounded. A MRAC algorithm is used for the estimation of the friction forces at the contact point between the end effector and the environment. Finally simulation and experimental results are given, to demonstrate the effectiveness of the proposed controller.

关键词： force control sliding control Lyapunov stability robot end effector friction force.

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Exact solution of Dirac equation for Scarf potential with new tensor coupling potential for spin and pseudospin symmetries using Romanovski polynomials

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Chinese Physics B 2014年第9期23卷 71-80页

作者： A.Suparmi C.Cari u.A.Deta Physics Department Faculty of Mathematics and Natural ScienceSebelas Maret University Department of Physics Faculty of Mathematics and Natural ScienceState University of Surabaya

The bound state solutions of Dirac equations for a trigonometric Scarf potential with a new tensor potential under spin and pseudospin symmetry limits are investigated using Romanovski polynomials. The proposed new tensor potential is inspired by superpotential form in supersymmetric （SuSY） quantum mechanics. The Dirac equations with trigonometric Scarf potential coupled by a new tensor potential for the pseudospin and spin symmetries reduce to Schrtdinger-type equations with a shape invariant potential since the proposed new tensor potential is similar to the superpotential of trigonometric Scarf potential. The relativistic wave functions are exactly obtained in terms of Romanovski polynomials and the relativistic energy equations are also exactly obtained in the approximation scheme of centrifugal term. The new tensor potential removes the degeneracies both for pseudospin and spin symmetries.

关键词： Scarf potential new tensor potential spin and pseudospin symmetries Romanovski polynomials

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