地基微波辐射计资料的质量控制及同化应用研究

针对地基微波辐射计反演资料的质量问题,利用北京区域7个站点的RPG-HATPRO型微波辐射计反演的温湿数据,在传统质量控制方法的基础上,通过增加双权重检查和偏差订正方法,设计了新的质量控制方案,而后针对质量控制后的温湿廓线开展了同化应用研究,结果表明:只有个别站点的反演温度误差较大,反演温度误差大的站点在质量控制前最大均方根误差为8℃,但在质量控制后均方根误差下降到4℃以内,误差下降50%以上,而对于反演温度误差小的站点,质量控制只对高层数据有所改善;进一步分析表明所有站点的反演相对湿度误差都比较大,在质量控制前反演的相对湿度均方根误差最大甚至达到50%,但在质量控制后所有站点反演的相对湿度均方根误差都降到20%以内,误差显著降低,同时经过质量控制后的反演温湿数据误差平均偏差降为0左右,误差满足高斯分布,符合同化的要求。同化试验表明:与控制试验相比,同化质量控制后的地基微波辐射计反演温湿廓线资料能有效改善模式对所有量级的6 h累积降水量预报,无论是降水中心位置预报还是降水量级预报,都使得模式降水预报更加趋近实况,同化试验还表明同化对温湿场有较大影响,使得模式温湿场更加合理,能有效提高模式的预报准确率。

遥感信息与作物生长模型同化应用的研究进展

卫星遥感技术能大面积、周期性地实时获取地表农作物信息,并且通过适当的反演方法能够定量地提供作物在区域尺度上的状况;作物生长模型应用物理数学方法从机制上定量地描述作物生长过程及其与环境因素之间的关系,在单点上对叶面积指数、生物量和产量等具有很好的模拟准确性。利用数据同化算法,将作物生长模型与遥感信息进行同化,已经成为当前农作物长势监测和产量预算研究中的重要手段。在简要回顾遥感数据和作物模型2种经典耦合方法的基础上,重点综述了连续同化和顺序同化2种不同同化方式的研究进展,并对数据同化算法进行了简单介绍,最后提出存在的一些问题并探讨了未来的研究方向。

面向数值同化应用的L波段秒级探空资料的质量控制方法研究

世界气象组织于2003年提出探空报文格式改革,推动探空资料从传统报文转向二进制秒级存储,这一举措促使秒级探空资料在数值预报模式中的应用成为未来的发展趋势。资料的质量控制是同化应用前极为重要的基础性工作,L波段秒级探空观测误差特点与传统常规探空显著不同,因此,本文发展了面向同化应用的L波段秒级探空资料的两步质量控制方法。第一步质控在集成常规探空质量控制方法的基础上,针对秒级探空的资料特性增加对应检查步骤,旨在尽可能剔除人为观测误差;第二步质控在同化系统中引入动态黑名单检查模块,同时借助同化系统自带的背景场检查来剔除观测和背景间偏离较大的资料,目的在于控制观测的代表性偏差。本文通过对比和分析质量控制前后观测样本的统计特征,并结合数值模式的实际同化分析结果,综合论证了两步质量控制方案的合理性:两步质控后资料异常大幅减少,观测背景差更接近高斯分布,资料的同化适用性更强,同化应用效果更优。本文的研究工作为今后L波段秒级探空资料在GRAPES(Global/Regional Assimilation and Prediction System)模式中的实现业务应用奠定了基础。

数值天气预报中卫星资料同化应用现状及发展

目前,数值天气预报的资源大都是来自卫星资料,并且卫星资料以其恰当的准确性和对数值天气与报的效果的改善占据所观测资料依据的大部分内容。而且,现代卫星资料的同化应用在跟随着全球观测系统建立后产生的大数据和新类型卫星资料的同化应用不断进步,也在自然因素对资料准确性的影响方面做出了很大的努力。本文主要针对数值天气预报中卫星资料同化应用的现状和未来的发展作简单的分析。

地基GPS资料反演大气可降水量理论进展

概述了地基GPS资料反演大气可降水量的基本原理,简单介绍了数据处理的应用软件和基本流程,系统地分析了国内外研究及应用方面的现状和最新理论进展,最后简述了当前的研究热点。

Carbon-supported ruthenium catalysts prepared by a coordination strategy for acetylene hydrochlorination

The development of efficient and stable non-mercury catalysts for the chlor-alkali industry is desirable but remains a great challenge.Herein,we design a series of ruthenium catalysts for acetylene hydrochlorination by regulating the electronic structure of ruthenium ions through coordination with various ligands(thiourea,phenanthroline,and L-lactic).The turnover frequencies(TOFs)and apparent activation energies for the acetylene hydrochlorination have a linear relationship with the binding energy of Ru3+in the ruthenium catalysts.The synergetic effect of the ruthenium ion and ligands plays an important role in acetylene hydrochlorination.The Ru-Thi/AC catalyst with thiourea as the ligand shows the highest TOF and stability in acetylene hydrochlorination.The present study provides a rational method to regulate the electronic structure of supported metal catalysts with high catalytic performance exhibited by the carbon-supported heterogeneous catalysts.

Transformation of carbon dioxide into valuable chemicals over bifunctional metallosalen catalysts bearing quaternary phosphonium salts

The chemical transformation of CO2under mild conditions remains a great challenge because of itsexceptional kinetic and thermodynamic stability.Two important reactions in the transformation ofCO2are the N‐formylation reaction of amines using hydrosilanes and CO2,and the cycloaddition ofCO2to epoxides.Here,we report the high efficiency of bifunctional metallosalen complexes bearingquaternary phosphonium salts in catalyzing both of these reactions under solvent‐free,mild conditionswithout the need for co‐catalysts.The catalysts’bifunctionality is attributed to an intramolecularcooperative process between the metal center and the halogen anion.Depending on the reaction,this activates CO2by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond(M–H)or the dual activation of epoxide via metal–oxygen coordinativebond(M–O).The one‐component catalysts are also shown to be easily recovered and reusedfive times without significant loss of activity or selectivity.The current results are combined withprevious work in the area to propose the relevant reaction mechanisms.

Layered transition-metal hydroxides for alkaline hydrogen evolution reaction

Hydrogen is a promising sustainable energy to replace fossil fuels owning to its high specific energy and environmental friendliness.Alkaline water electrolysis has been considered as one of the most prospective technologies for large scale hydrogen production.To boost the sluggish kinetics of hydrogen evolution reaction(HER)in alkaline media,abundant materials have been designed and fabricated.Herein,we summarize the key achievements in the development of layered transition-metal hydroxides[TM(OH)x]for efficient alkaline HER.Based on the structure of TM(OH)x,the mechanism of synergistic effect between TM(OH)x and HER active materials is illuminated firstly.Then,recent progress of TM(OH)x-based HER catalysts to optimize the synergistic effect are categorized as TM(OH)x and active materials,including species,structure,morphology and interaction relationship.Furthermore,TM(OH)x-based overall water splitting electrocatalysts and electrodes are summarized in the design principles for high activity and stability.Finally,some of key challenges for further developments and applications of hydrogen production are proposed.

CORRECTION OF ASYMMETRIC STRENGTHENING OF QUIKSCAT WIND FIELD AND ASSIMILATION APPLICATION IN TYPHOON SIMULATION

As an approach to the technological problem that the wind data of QuikSCAT scatterometer cannot accurately describe the zone of typhoon-level strong wind speed, some objective factors such as the typhoon moving speed, direction and friction are introduced in this study to construct the asymmetric strengthening of the QuikSCAT wind field. Then by adopting a technology of four-dimensional data assimilation, an experiment that includes both the assimilation and forecasting phases is designed to simulate Typhoon Rananim numerically. The results show that with model constraints and adjustment, this technology can incorporate the QuikSCAT wind data to the entire column of the model atmosphere, improve greatly the simulating effects of the whole-column wind, pressure field and the track as well as the simulated typhoon intensity covered by the forecast phase, and work positively for the forecasting of landfall locations.

Application of isotopic and hydro-geochemical methods in identifying sources of mine inrushing water

Isotopic and hydro-geochemical surveys were carried out to identify the source of mine inrushing water at the #73003 face in the Laohutai Mine. Based on the analysis of isotopes and hydro-chemical features of surface water, groundwater from different levels and the inrushing water, a special relationship between water at the #73003 face and cretaceous water has been found. The results show that the isotopic and hydro-chemical features of the inrushing water are completely different from those of other groundwater bodies, except for the cretaceous water. The isotopic and hydrochemical characteristics of cretaceous water are similar to the inrushing water of the #73003 face, which aided with obtaining the evidence for the possible source of the inrushing water at the #73003 face. The isotope calculations show that the inrushing water at the #73003 face is a mixture of cretaceous water and Quaternary water. Water from the cretaceous conglomerate is the main source, accounting for 67% of the inrushing water, while the Quaternary water accounts for 33%. The conclusion is also supported by a study of inrushing-water channels and an active fault near the inrushin^-water plot on the #73003 face.

Protective Effects of Vitamin E on Diabetes-induced Oxidative Stress Status and Homocysteine in the Rat Heart

Objective： We aimed to investigate protective effects ofvit E on oxidative stress status and homocysteine （Hey） in cardiac tissue of diabetic rats. Methods： Sixteen Wistar male rats were treated with STZ （streptozotocin） （60 mg/kg） to induce diabetes. Diabetic rats were divided into two groups： NTD （non-treated diabetic） and VETD （vit E-treated diabetic） rats. The VETD group received 300 mg/kg vit E with daily feeding. Eight normal rats of the same age were used as the control group. After 6 weeks, the rats were anesthetized, their cardiac tissue was removed, and homogenated supernatant was separated. Samples were assayed for TAC （total antioxidant capacity）, LPO （lipid peroxidation）, nitrite （NO2）, nitrate （NO3）, and Hcy. Key Findings： The contents of LPO, NO3 and Hcy in NTD compared to control group indicate a significant increase, but the levels of these parameters decreased in VETD （p 〈 0.05）. There was a significant decrease in the amount of TAC in the NTD group but in VETD group, that significantly increased （p 〈 0.05）. The amount of NO2 in NTD and VETD groups, compared to the control group, did not show any significant changes （p 〉 0.05）. Conclusions： Significant decrease of oxidative stress and Hey in the cardiac tissue caused by vit E supplementation strongly indicated that this radical scavenger may promote a protective effect on diabetic cardiomyopathy through the attenuation of oxidative stress and increase antioxidant defense mechanism.

Commutators of Calderón-Zygmund operators related to admissible functions on spaces of homogeneous type and applications to Schrdinger operators

Let X be an RD-space. In this paper, the authors establish the boundedness of the commutator Tbf = bTf-T(bf) on Lp , p∈(1,∞), where T is a Calderón-Zygmund operator related to the admissible function ρ and b∈BMOθ(X)BMO(X). Moreover, they prove that Tb is bounded from the Hardy space H1ρ(X) into the weak Lebesgue space L1weak(X). This can be used to deal with the Schrdinger operators and Schrdinger type operators on the Euclidean space Rn and the sub-Laplace Schrdinger operators on the stratified Lie group G.

Implicit Sampling,with Application to Data Assimilation

There are many computational tasks, in which it is necessary to sample a given probability density function （or pdf for short）, i.e., to use a computer to construct a sequence of independent random vectors x~ （i ---- 1, 2, ~ ~ ~ ）, whose histogram converges to the given pdf. This can be difficult because the sample space can be huge, and more importantly, because the portion of the space, where the density is significant, can be very small, so that one may miss it by an ill-designed sampling scheme. Indeed, Markov- chain Monte Carlo, the most widely used sampling scheme, can be thought of as a search algorithm, where one starts at an arbitrary point and one advances step-by-step towards the high probability region of the space. This can be expensive, in particular because one is typically interested in independent samples, while the chain has a memory. The authors present an alternative, in which samples are found by solving an algebraic equation with a random right-hand side rather than by following a chain; each sample is independent of the previous samples. The construction in the context of numerical integration is explained, and then it is applied to data assimilation.

The four dimensional variational data assimilation with multiple regularization parameters as a weak constraint(Tikh-4D-Var) and its preliminary application on typhoon initialization

Traditional variational data assimilation （VDA） with only one regularization parameter constraint cannot produce optimal error tuning for all observations. In this paper, a new data assimilation method of ＂four dimensional variational data assimilation （4D-Var） with multiple regularization parameters as a weak constraint （Tikh-4D-Var）＂ is proposed by imposing different reg- ularization parameters for different observations. Meanwhile, a new multiple regularization parameters selection method, which is suitable for actual high-dimensional data assimilation system, is proposed based on the posterior information of 4D-Var system. Compared with the traditional single regularization parameter selection method, computation of the proposed multiple regularization parameters selection method is smaller. Based on WRF3.3.1 4D-Vat data assimilation system, initiali- zation and simulation of typhoon Chaba （2010） with the new Tikh-4D-Var method are compared with its counterpart 4D-Var to demonstrate the effectiveness of the new method. Results show that the new Tikh-4D-Var method can accelerate the con vergence with less iterations. Moreover, compared with 4D-Var method, the typhoon track, intensity （including center surface pressure and maximum wind speed） and structure prediction are obviously improved with Tikh-4D-Var method for 72-h pre- diction. In addition, the accuracy of the observation error variances can be reflected by the multiple regularization parameters.

Homogenization of a Class of Nonlinear Variational Inequalities with Applications in Fluid Film Flow

The authors consider the homogenization of a class of nonlinear variational inequalities,which include rapid oscillations with respect to a parameter.The homogenization of the corresponding class of differential equations is also studied.The results are applied to some models for the pressure in a thin fluid film fluid between two surfaces which are in relative motion.This is an important problem in the lubrication theory.In particular,the analysis includes the effects of surface roughness on both faces and the phenomenon of cavitation.Moreover,the fluid can be modeled as Newtonian or non-Newtonian by using a Rabinowitsch fluid model.

A MATHEMATICAL APPROACH TO DESYNCHRONIZATION OF COUPLED OSCILLATORS： APPLICATION TO A NEURONAL ENSEMBLE

Synchronization of neurons plays an important role in vision, movement and memory. However, many neurological disorders such as epilepsies, Parkinson disease and essen- tial tremor are related to excessive synchronization of neurons. In the line of therapy, stimulations to these pathologically synchronized neurons should be capable of breaking synchrony. As the first step of designing an effective stimulation, we consider desynchro- nization problem of coupled limit-cycle oscillators ensemble. First, the desynchronization problem is redefined in a nonlinear output regulation framework. Then, we design an output regulator （stimulation） which forces limit-cycle oscillators to track exogenous sinusoidal references with different phases. The proposed stimulation is robust against variations of oscillators＇ frequencies. Mathematical analysis and simulation results reveal the efficiency of the proposed technique.