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rates of generation and growth of the continental crust

Geoscience Frontiers 2019年第1期10卷 165-173页

作者： Chris Hawkesworth Peter A.Cawood Bruno Dhuime School of Earth Sciences University of Bristol School of Earth Atmosphere and Environment Monash University CNRS-UMR 5243 Géosciences Montpellier Université de Montpellier

Models for when and how the continental crust was formed are constrained by estimates in the rates o crustal growth. The record of events preserved in the continental crust is heterogeneous in time with distinctive peaks and troughs of ages for igneous crystallisation, metamorphism, continental margin and mineralisation. For the most part these are global signatures, and the peaks of ages tend to b associated with periods of increased reworking of pre-existing crust, reflected in the Hf isotope ratios o zircons and their elevated oxygen isotope ratios. Increased crustal reworking is attributed to periods o crustal thickening associated with compressional tectonics and the development of supercontinents Magma types similar to those from recent within-plate and subduction related settings appear to hav been generated in different areas at broadly similar times before ~3.0 Ga. It can be difficult to put th results of such detailed case studies into a more global context, but one approach is to consider when plate tectonics became the dominant mechanism involved in the generation of juvenile continental crust The development of crustal growth models for the continental crust are discussed, and a number o models based on different data sets indicate that 65%-70% of the present volume of the continental crus was generated by 3 Ga. Such estimates may represent minimum values, but since ~3 Ga there has been reduction in the rates of growth of the continental crust. This reduction is linked to an increase in th rates at which continental crust is recycled back into the mantle, and not to a reduction in the rates a which continental crust was generated. Plate tectonics results in both the generation of new crust and it destruction along destructive plate margins. Thus, the reduction in the rate of continental crustal growth at ~3 Ga is taken to reflect the period in which plate tectonics became the dominant mechanism b which new continental crust was generated.

关键词： Continental crust growth curves rates of crustal growth Tectonics

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Prediction of proton-induced SEE error rates for the VATA160 ASIC

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Nuclear Science and Techniques 2017年第1期28卷 88-93页

作者： Kai Xi Di Jiang Shan-Shan Gao Jie Kong Hong-Yun Zhao Hai-Bo Yang Tian-Qi Liu Bin Wang Bing Ye Jie Liu Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026 China

We predict proton single event effect(SEE)error rates for the VATA160 ASIC chip on the Dark Matter Particle Explorer(DAMPE) to evaluate its radiation tolerance.Lacking proton test facilities,we built a Monte Carlo simulation tool named PRESTAGE to calculate the proton SEE cross-sections.PRESTAGE is based on the particle transport toolkit Geant4.It adopts a location-dependent strategy to derive the SEE sensitivity of the device from heavy-ion test data,which have been measured at the HI-13 tandem accelerator of the China Institute of Atomic Energy and the heavy-ion research facility in Lanzhou.The AP-8,SOLPRO,and August 1972 worst-case models are used to predict the average and peak proton fluxes on the DAMPE orbit.Calculation results show that the averaged proton SEE error rate for the VATA160 chip is approximately 2.17×10^(-5)/device/day.Worst-case error rates for the Van Allen belts and solar energetic particle events are 1-3 orders of magnitude higher than the averaged error rate.

关键词： Proton ASIC Single event effects Error rates

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Optical properties and radiative rates of Nd^(3+) doped zinc-sodium phosphate glasses

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Journal of Rare Earths 2019年第3期37卷 253-259页

作者： A.A.El-Maaref Shimaa Badr Kh.S.Shaaban E.A.Abdel Wahab M.M.ElOkr Physics Department Faculty of Science Al-Azhar University Modern Academy for Engineering & Technology Chemistry Department Faculty of Science Al-Azhar University

Preparation using melt quenching technique and optical characterizations of Nd^(3+) doped Zn-Na phosphate glasses are presented. The structure of the present glasses was studied using X-ray diffraction and FT-IR spectroscopy. UV-vis spectra of the present glasses were analyzed at different concentrations of Nd_2 O_3. The effect of neodymium concentration on the density and energy band gap was investigated. The density of the present glasses slightly increases with the increasing of Nd_2 O_3. A small variation of energy band gap with the increasing of neodymium content is observed as well, while E_g values decrease with the increase of Nd_2 O_3 content. The E_g values lie between 4.36 and 4.69 eV. Based on the measured optical spectra, Judd-Ofelt theory was used to determine the optical parameters such as line strengths, optical intensity parameters(Ω_t), transition probabilities, and transition lifetimes. Hypersensitive transitions were identified in the absorption spectrum, the greatest line strengths are recorded at the transitions^2 G_(7/2)+ ~4 G_(5/2), ~4 S_(3/2) + ~4 F_(7/2) and ~4 D_(1/2) + ~4 D_(3/2)+ ~4 D_(5/2) + ~2 I_(11/2) with wavelengths of 580, 475 and 355 nm,respectively. Lifetimes of the important ~4 F_(3/2) laser-level were determined; which show decreasing trend with the increasing of Nd_2 O_3 content and are found to be between 0.838 and 1.595 ms. The uncertainty of the present results was estimated. The RMS deviations were determined, which show lower values than those in the literature.

关键词： Phosphate glass UV-vis spectroscopy Judd-Ofelt Radiative rates Rear earth ions

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Sensor Fault Estimation and Fault-Tolerant Control for a Class of Takagi-Sugeno Markovian Jump Systems with Partially Unknown Transition rates Based on the Reduced-Order Observer

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Journal of Systems Science & Complexity 2018年第6期31卷 1405-1422页

作者： LI Xiaohang LU Dunke ZHANG Wei ZHU Fanglai School of Electronic and Electric Engineering Shanghai University of Engineering ScienceShanghai 201620China School of Electrical Engineering and Automation Henan Polytechnic UniversityJiaozuo 454010China School of Electronic and Electric Engineering Shanghai University of Engineering ScienceShanghai 201620China. Engineering Training Center Shanghai University of Engineering ScienceShanghai 201620China. College of Electronics and Information Engineering Tongji UniversityShanghai 200093China.

This paper addresses the problem on sensor fault estimation and fault-tolerant control for a class of Takagi-Sugeno Markovian jump systems,which are subjected to sensor faults and partially unknown transition rates.First,the original plant is extended to a descriptor system,where the original states and the sensor faults are assembled into the new state vector.Then,a novel reduced- order observer is designed for the extended system to simultaneously estimate the immeasurable states and sensor faults.Second,by using the estimated states obtained from the designed observer,a state- feedback fault-tolerant control strategy is developed to make the resulting closed-loop control system stochastically stable.Based on linear matrix inequality technique,algorithms are presented to compute the observer gains and control gains.The effectiveness of the proposed observer and controller are validated by a numerical example and a compared study,respectively,and the simulation results reveal that the proposed method can successfully estimate the sensor faults and guarantee the stochastic stability of the resulting closed-loop system.

关键词： Fault-tolerant control Markovian jump system partially unknown transition rates reduced- order observer sensor fault estimation T-S fuzzy system

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rates of convergence of M-estimators for partly linear models involving time series

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Science China Mathematics 1995年第5期38卷 533-541页

作者：施沛德郑忠国 Department of Probability and Statistics Peking University Beijing 100871 China)

The asymptotic behaviour of M-estimalors constructed with B-spline method based on strictly stationary β-mixing observations of a partly linear model is dealt with. Under some regular conditions, it is proved that the M-estimators of the vector of parameters are asymptotically normal and the M-estimators of the nonparametric component achieve the optimal convergence rates for nonparametric regression. Our asymptotic theory includes L1-, L2-, Lp-norm, and Huber estimators as special cases.

关键词： M-estimator B-splines optimal rates of convergence strictly stationary sequence β-mixing.

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Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

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Science China Earth Sciences 2010年第4期53卷 568-574页

作者： CHENG Hong & ZOU XueYong State Key Laboratory of Earth Surface Processes and Resource Ecology,Beijing Normal University,Beijing 100875,China MOE Engineering Center of Desertification and Blown-sand Control,Beijing Normal University,Beijing 100875,China Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China,Beijing Normal University,Beijing 100875,China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing China MOE Engineering Center of Desertification and Blown-sand Control Beijing Normal University Beijing China Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing China

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous work.Aeolian sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground surface.Despite extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field observations.One key problem is a few of sufficient research on liftoff rates of saltating sand grains(also called the number of liftoff sand grains per unit time and per unit bed area).It is necessary to re-search in advance liftoff rates of saltating sand grains.We redeveloped liftoff rates of saltating sand grains by establishing an optimization model based on the flux of aeolian sand flow at different heights of the sampler in wind tunnel and the simulated capture of saltating sand grains by different heights of the sampler that are from different liftoff position(distance from the sampler) in order to revise previous inversion condition of liftoff rates of saltating sand grains.Liftoff rates increased rapidly with increasing wind speed.For frictional wind velocities of u=0.67,0.77,0.82,0.83,and 0.87 m s-1,liftoff rates were 3840,954502,5235114,5499407,and 7696291 sand grain s-1 m-2,respectively.These rates could be expressed as the square of the instantaneous frictional wind velocity and a constant(0.663) that differs from the critical(threshold) frictional wind velocity at which saltation begins.Although our results require additional experimental validation and the simple optimization model must be improved,they nonetheless provide a strong basis for future research.

关键词： liftoff rates of saltating sand grains optimization model wind tunnel two-phase gas-solid flow

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CONVERGENCE rates TO NONLINEAR DIFFUSIVE WAVES FOR SOLUTIONS TO NONLINEAR HYPERBOLIC SYSTEM

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Acta Mathematica Scientia 2019年第1期39卷 46-56页

作者：耿世锋唐炎娟 School of Mathematics and Computational Science Xiangtan University

This article is involved with the asymptotic behavior of solutions for nonlinear hyperbolic system with external friction. The global existence of classical solutions is proven,and L^p convergence rates are obtained. ... 详细信息

关键词： convergence rates nonlinear diffusion waves nonlinear hyperbolic system external friction

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GLOBAL EXISTENCE AND OPTIMAL CONVERGENCE rates OF SOLUTIONS FOR THREE-DIMENSIONAL ELECTROMAGNETIC FLUID SYSTEM

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Acta Mathematica Scientia 2019年第2期39卷 469-490页

作者：李银位瑞英姚正安 School of Mathematics and Statistics Shaoguan University Department of Mathematics Sun Yat-sen University

In this article, we study the electromagnetic fluid system in three-dimensional whole space R^3. Under assumption of small initial data, we establish the unique global solution by energy method. Moreover, we obtain the time decay rates of the higher-order spatial derivatives of the solution by combining the L^p-L^q estimates for the linearized equations and an elaborate energy method when the L^1-norm of the perturbation is bounded.

关键词： electromagnetic fluid decay rates Fourier-splitting method

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Deformation at low and high stress-loading rates

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Geoscience Frontiers 2019年第1期10卷 43-54页

作者： Claudia A.Trepmann Lina Seybold Department of Earth and Environmental Sciences Ludwig-Maximilians University

In an extensional shear zone in the Talea Ori, Crete, quartz veins occur in high-pressure low-temperature metamorphic sediments at sites of dilation along shear band boundaries, kink band boundaries and boudin necks. Bent elongate grains grown epitactically from the host rock with abundant fluid inclusion trails parallel to the vein wall indicate vein formation by crack-seal increments during dissolutionprecipitation creep of the host rock. The presence of sutured high-angle grain boundaries and subgrains shows that temperatures were sufficiently high for recovery and strain-induced grain boundary migration, i.e. higher than 300 -350℃, close to peak metamorphic conditions. The generally low amount of strain accumulated by dislocation creep in quartz of the host rock and most veins indicates low bulk stress conditions of a few tens of MPa on a long term. The time scale of stress-loading to cause cyclic cracking and sealing is assumed to be lower than the Maxwell relaxation time of the metasediments undergoing dissolution-precipitation creep at high strain rates(10^(-10) s^(-1) to 10^(-9) s^(-1)), which is on the order of hundred years. In contrast, some veins discordant or concordant to the foliation show heterogeneous quartz microstructures with micro-shear zones, sub-basal deformation lamellae, shortwavelength undulatory extinction and recrystallized grains restricted to high strain zones. These microstructures indicate dislocation glide-controlled crystal-plastic deformation(low-temperature plasticity) at transient high stresses of a few hundred MPa with subsequent recovery and strain-induced grain boundary migration at relaxing stresses and temperatures of at least 300 -350℃. High differential stresses in rocks at greenschist-facies conditions that relieve stress by creep on the long term, requires fast stress-loading rates, presumably by seismic activity in the overlying upper crust. The time scale for stress loading is controlled by the duration of the slip event along a fault, i.e. a few seconds to minutes.

关键词： High-stress crystal plasticity Crack-seal Seismic cycle Stress-loading rates Talea Ori Crete

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PMCMC for Term Structure of Interest rates under Markov Regime Switching and Jumps

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Journal of Systems Science and Information 2020年第2期11卷 159-169页

作者： Xiangdong LIU Xianglong LI Shaozhi ZHENG Hangyong QIAN Department of Statistics Jinan UniversityGuangzhou 510632China

A parameter estimation method,called PMCMC in this paper,is proposed to estimate a continuous-time model of the term structure of interests under Markov regime switching and jumps.There is a closed form solution to term structure of interest rates under Markov regime.However,the model is extended to be a CKLS model with non-closed form solutions which is a typical nonlinear and non-Gaussian state-space model(SSM)in the case of adding jumps.Although the difficulty of parameter estimation greatly prevents from researching models,we prove that the nonlinear and non-Gaussian state-space model has better performances in studying volatility.The method proposed in this paper will be implemented in simulation and empirical study for SHIBOR.Empirical results illustrate that the PMCMC algorithm has powerful advantages in tackling the models.

关键词： PMCMC term structure of interest rates state-space models regime switching jump-diffusion

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