Analysis on Sixth-Order Compact Approximations with Richardson Extrapolation for 2D Poisson Equation

By using Richardson extrapolation and fourth-order compact finite difference scheme on different scale grids, a sixth-order solution is computed on the coarse grid. Other three techniques are applied to obtain a sixth-order solution on the fine grid, and thus give out three kinds of Richardson extrapolation-based sixth order compact computation methods. By carefully analyzing the truncation errors respectively on 2D Poisson equation, we compare the accuracy of these three sixth order methods theoretically. Numerical results for two test problems are discussed.

GRA BASED ANALYSIS ON FACTORS INFLUENCING CO_2 EMISSIONS IN CHINA

How to achieve the objective of reducing CO2 emissions has been an academic focus in China recently. The factors influencing CO2 emissions are the vital issue to accomplish the arduous target. Firstly, three influential factors, the energy consumption, the proportion of tertiary industry in gross domestic product （GDP）, and the degree of dependence on foreign trade, are carefully selected, since all of them have closer grey relation with China＇s COz emissions compared with others when the grey relational analysis （GRA） method is applied. The study highlights co-integration relation of these four variables using the co-integration analysis method. And then a long-term co-integration equation and a short-term error correction model of China＇s CO2 emissions are devel- oped. Finally, the comparison is exerted between the forecast value and the actual value of China＇s CO2 emissions based on error correction model. The results and the relevant statistics tests show that the pro- posed model has better explanation capability and credibility.

AI-Enabled COVID-19 Outbreak Analysis and Prediction: Indian States vs. Union Territories

The COVID-19 disease has already spread to more than 213 countries and territories with infected(confirmed)cases of more than 27 million people throughout the world so far,while the numbers keep increasing.In India,this deadly disease was first detected on January 30,2020,in a student of Kerala who returned from Wuhan.Because of India’s high population density,different cultures,and diversity,it is a good idea to have a separate analysis of each state.Hence,this paper focuses on the comprehensive analysis of the effect of COVID-19 on Indian states and Union Territories and the development of a regression model to predict the number of discharge patients and deaths in each state.The performance of the proposed prediction framework is determined by using three machine learning regression algorithms,namely Polynomial Regression(PR),Decision Tree Regression,and Random Forest(RF)Regression.The results show a comparative analysis of the states and union territories having more than 1000 cases,and the trained model is validated by testing it on further dates.The performance is evaluated using the RMSE metrics.The results show that the Polynomial Regression with an RMSE value of 0.08,shows the best performance in the prediction of the discharged patients.In contrast,in the case of prediction of deaths,Random Forest with a value of 0.14,shows a better performance than other techniques.

HY-2卫星微波散射计海面风矢量场反演技术研究

主要针对HY-2卫星微波散射计,提出反演海面风矢量模型算法,并进行误差精度分析,给出了HY-2卫星微波散射计数据获取、预处理、风矢量场反演和产品制作技术流程,为HY-2卫星发射上天后能尽快发挥应有的效益做好技术准备,以此推动我国海洋微波遥感技术的发展。

FY-2C星云图成像技术

介绍了风云二号(FY-2)气象卫星星上成像系统的主要功能和技术指标、云图的生成与传输,以及数传与转发技术。阐述了以太阳为基准采用星上预同步、地面同步/数据缓冲器(S/DB)进行精同步的同步成像技术的卫星成像系统设计原理。分析了卫星姿态动力学对自旋轴定向稳定的影响、扫描辐射计扫描机构步进对自旋周期稳定度的影响、卫星摇摆运动造成的云图几何畸变等产生成像误差的因素,以及采取的补偿修正方案。飞行试验结果表明,C星的云图网格配准精度优于1个可见像素,章动角和摇摆角也符合设计要求。

Synthesis, Crystal Structure, Fluorescent Property and DFT Calculations of a New Zn(Ⅱ) Complex Based on 3-(2-Pyridyl)-5-(4-pyridyl)-1H-1,2,4-triazole

A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877（3）, b = 0.7483（9）, c = 1.2492（2） A, b = 92.681（2）°, V = 2230.6（4） A^3, Z = 4, Dc = 1.572 g/cm^3, m = 1.143 mm^-1, Mr = 527.85 and F（000） = 1080. The final R = 0.0581 and wR = 0.0898 with I 〉 2s（I）. 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory（DFT） were employed in order to explicate the stability and chemical reactivity of 2,4＇-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.

基于宽频光源--FP腔的大气CO_2检测系统误差分析

介绍了由宽频光源和法布里--珀罗(Fabry--Pérot,FP)谐振腔组成的CO_2检测系统。结合常见的主动光学系统误差分析方法,对系统的各个误差项进行了定量化分析。系统误差来源于光源能量波动、环形器串扰、FP腔谱线变动和探测器噪声四个方面。通过建模计算了各独立误差项对差分信号数值的影响,确定了4项主要的系统误差。传统大气检测误差分析将硬件系统误差直接关联到浓度数据上,本文误差分析方法把硬件误差和反演算法误差剥离,对于提高系统的工作能力有更好的指导意义。

SYNTHESIS,CHARACTERIZATION,THERMAL DEGRADATION AND ELECTRICAL CONDUCTIVITY OF OLIGO[2-(2-HYDROXYPHENYLIMINOMETHYLBENZYLIDENE)AMINOPHENOL]AND OLIGOMER-METAL COMPLEXES

The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...

SYNTHESIS,CHARACTERIZATION,THERMAL DEGRADATION AND ELECTRICAL CONDUCTIVITY OF OLIGO[2-(THIEN-2-YLMETHYLENE)AMINOPHENOL]AND OLIGOMER-METAL COMPLEXES

The optimum reaction conditions of the oxidative polycondensation of 2-(thien-2-yl-methylene)aminophenol (2-TMAP) has been accomplished by using air O_2,H_2O_2 and NaOCl oxidants in an aqueous alkaline medium between 20℃and 90℃.The structures of the monomer and oligomer were confirmed by FT-IR,UV-Vis,~1H-NMR and ^(13)C-NMR and elemental analysis.TGA-DTA,size exclusion chromatography(SEC) techniques and solubility tests were applied for characterization.The ~1H-NMR and ^(13)C-NMR data show that the polymeriz...

STUDIES ON ORGANIC PEROXIDE/N, NDI(2-α-METHYL-ACRYLOYLOXY PROPYL)-PARA-TOLUIDINE BINARY SYSTEMS

The polymerization of methyl methacrylate (MMA) initiated by organic peroxide and polymerizable aromatic tertiary amine such as N, N-di (2-α-methylacryloyloxy propyl)-p-toluidine (MP)_2PT binary system has been studied. It was found that the (MP)_2PT promotes MMA polymerization, and the kinetics of MMA polymerization fits the radical polymerization rate equation. Based on the ESR studies and the end-group analysis the initiation mechanism is proposed.

Identification of N-Methyl Bis(2-(Alkyloxy-Alkylphosphoryloxy)Ethyl) Amines by LC-HRMS/MS

N-Methyl bis(2-(alkyloxy-alkylphosphoryloxy)ethyl)amines, which are abbreviated as PNPs, are a series of new skeleton chemicals belonging to schedule 2.B.04 chemicals of Chemical Weapons Convention (CWC). PNPs are important markers of chemical warfare agents because they are structurally relative to both nerve agents and N-mustards. In this study, fragmentation pathways of the most characteristic fragment ions in Q-TOF mass spectrometry were proposed based on the information from accurate mass and secondary fragmentations of product ions scan experiments. Results indicated that the base ion in LC/HRMS was the quasi-molecular ion [M+H]+. In LC-HRMS/MS, it was [M+H-CnH2n+1P(O)(OH)CmH2m+1O]+ fragment ion which was formed by losing an alkyloxy alkylphosphoryloxy group from the quasi-molecular ion. The diagnostic ion m/z84.0814 was identified as [C5H10N]+, which was the group of (CH2=CH)2N+(H)CH3. PNPs have two protonated centers. One is on the N atom, the other is on the O atom (P=O). O-n-propyl PNPs generally exhibited two fragmentation pathways. Firstly, the quasi-molecular ion [M+H]+ lost a propoxy alkylphosphoryloxy group to produce [R1P(OH+)(O-n-C3H7)OCH2CH2N(CH3)CH=CH2]+, which could be fragmented further to produce [C5H10N]+ ion. Secondly, [R1P(OH+)(O-n-C3H7) OCH=CH2]+ ions were produced from [M+H]+ and fragmented further to produce the abundant ions [R1P(OH+)(OH)OCH =CH2]. However, O-isopropyl PNPs characteristically produced weak fragment ions [M+H-C3H6]+, which were presumably formed via loss of CH3CH=CH2 from [M+H]+. Other PNPs showed similar fragmentation pathways as O-n-propyl PNPs. On the summarization of the MS fragmentation pathways of PNPs, LC-HRMS/MS quantitative and qualitative methods were developed and applied to analyze N-Methyl bis(2-(butoxy-methylphosphoryloxy)ethyl]amine in high background organic samples. The analytical results had successfully supported the sample preparation for the 33rd official proficiency test of Organization for Prohibition of Chemical Weapons (OPCW).

On the road towards the global analysis of human synapses

Synapses are essential units for the flow of information in the brain.Over the last 70 years,synapses have been widely studied in multiple animal models including worms,fruit flies,and rodents.In comparison,the study of human synapses has evolved significantly slower,mainly because of technical limitations.However,three novel methods allowing the analysis of molecular,morphological,and functional properties of human synapses may expand our knowledge of the human brain.Here,we briefly describe these methods,and evaluate how the information provided by each unique approach may contribute to the functional and anatomical analysis of the synaptic component of human brain circuitries.In particular,using tissue from cryopreserved human brains,synaptic plasticity can be studied in isolated synaptosomes by fluorescence analysis of single-synapse long-term potentiation（FASS-LTP）,and subpopulations of synapses can be thoroughly assessed in the ribbons of brain tissue by array tomography（AT）.Currently,it is also possible to quantify synaptic density in the living human brain by positron emission tomography（PET）,using a novel synaptic radio-ligand.Overall,data provided by FASS-LTP,AT,and PET may significantly contribute to the global understanding of synaptic structure and function in both healthy and diseased human brains,thus directly impacting translational research.

对ENVISAT ASAR level 2算法固有误差的分析

欧洲空间局的ENVISAT ASAR level 2算法是从合成孔径雷达(SAR)单视复图像反演涌浪方向谱的算法。该算法假设双峰海浪谱的SAR图像交叉谱是涌浪的图像交叉谱和风浪的图像交叉谱之和。实际上双峰海浪谱的SAR图像交叉谱中还有一个混合项,正是该混合项导致ENVI-SAT ASAR level 2算法有固有误差。利用遥感仿真的方法分析了不同海况条件下该算法的这一固有误差,结果表明,只有在有效波高较小、或风浪的成分较少、或双峰海浪的传播方向较靠近SAR距离向、或波长较长时固有误差才较小,ENVISAT ASAR level 2算法对海浪谱的反演才较为适用。

二维Volterra-Fredholm型积分方程问题Taylor配置解法及误差分析

利用Taylor配置方法,研究二维Volterra-Fredholm型积分方程问题的数值解.即对研究的积分方程问题进行Taylor配置离散,将积分方程问题转化为代数方程进行求解,建立了Taylor逼近解的求解格式,给出了配置解与精确解的误差估计结果以及阐述理论分析的3个数值例子.

基于改进核范数的2DPCA人脸识别算法研究

传统的二维主成分分析法广泛应用于图像特征提取,为了使此算法更加有效,提出了一种结构化二维算法,即核范数2DPCA算法(N-2-DPCA)。该算法基于核范数重构误差准则,将核范数最优化问题转化为基于F范数的最优化问题,然后通过采用迭代方法寻找到最佳投影矩阵,最后运用最小欧氏距离规则识别出待识别人脸的身份。在此基础之上,将N-2-DPCA扩展到基于双边投影的算法(N-B2-DPCA),采用曲线搜索算法寻找到双边投影矩阵,继而进行识别。最后将提出的算法在FERET和Yale B人脸数据库中进行人脸识别评估,实验结果表明所提出的算法与L1-2DPCA相比,重建误差降低了2.19%,识别率提高了2.03%,性能更好。

Integrated statistical and machine learning analysis provides insight into key influencing symptoms for distinguishing early-onset type 2 diabetes

Background: Being able to predict with confidence the early onset of type 2 diabetes from a suite of signs and symptoms (features) displayed by potential sufferers is desirable to commence treatment promptly. Late or inconclusive diagnosis can result in more serious health consequences for sufferers and higher costs for health care services in the long run.Methods: A novel integrated methodology is proposed involving correlation, statistical analysis, machine learning, multi-K-fold cross-validation, and confusion matrices to provide a reliable classification of diabetes-positive and -negative individuals from a substantial suite of features. The method also identifies the relative influence of each feature on the diabetes diagnosis and highlights the most important ones. Ten statistical and machine learning methods are utilized to conduct the analysis.Results: A published data set involving 520 individuals (Sylthet Diabetes Hospital, Bangladesh) is modeled revealing that a support vector classifier generates the most accurate early-onset type 2 diabetes status predictions with just 11 misclassifications (2.1% error). Polydipsia and polyuria are among the most influential features, whereas obesity and age are assigned low weights by the prediction models.Conclusion: The proposed methodology can rapidly predict early-onset type 2 diabetes with high confidence while providing valuable insight into the key influential features involved in such predictions.

Development and analysis of a novel AF11-2 aptamer capable of enhancing the fluorescence of aflatoxin B1

Aflatoxin B1(AFB1)is one of the most common mycotoxins that threatens human health.As singlestranded oligonucleotides with high affinity and specificity,aptamers have incomparable effect on the targeted detection of AFB1.Herein,after 11 rounds of selection and analysis using a modified affinity chromatography-based SELEX strategy,the truncated 37 nt aptamer AF11-2 was successfully obtained.The aptamer shows good detection performance for AFB1,and can sensitively detect AFB1 in the range of 100-1000 nmol/L,with a detection limit of 42 nmol/L.In the detection of pretreated edible peanut oil samples,AF11-2 aptamer also showed a high recovery rate and good stability for AFB1,and achieved satisfactory results.In addition,AF11-2 aptamer can significantly enhance the fluorescence ability of AFB1,which is not available in traditional Afla17-2-3 aptamer.After molecular docking analysis,it was found that AF11-2 and Afla17-2-3 had different nucleotide binding sites for AFB1.Afla17-2-3 binds to the carbonyl O of AFB1,while AF11-2 binds to the pyrrolic O of AFB1,which may be the main reason that AF11-2 can enhance the fluorescence of AFB1.

Error Correction Strategy Use in the Second Language Classroom： A Study of Junior High School English Teachers in Ghana

Error correction, in recent times, is seen as one of the important teaching processes in L2 （second language） learning, because comprehensible inputs alone is insufficient for acquisition of language. However, few L2 teachers know much about error analysis and how to correct errors in the L2 classroom. Error correction is a very complicated and a thorny issue in L2 teaching and learning. L2 teachers, therefore, need to be armed with ways in which errors can be treated to ensure maximum effect yet with less harm to learners. Identifying learners＇ errors is very important in L2 learning, but how to correct them to give the desired effect is equally important and very challenging to L2 teachers. It is therefore crucial to initiate a study in Ghana to find out how errors are corrected in the Ghanaian English language classroom. This case study used complete observation and semi-structured interview as data collection strategies to identify error correction strategies/types English teachers use in the Ghanaian JHS （Junior High School） classroom and how error correction/treatment can be improved to facilitate English language teaching and learning. The findings of the study showed that explicit error correction technique was the most commonly used followed by recast, elicitation, metalinguistic clues, clarification request, repetition, and cues. It was also found that the causes of the disparity in the use of the various error correction types were inadequate teacher preparation, incompetence in English language, limited knowledge in error correction, caliber of students, and insufficient teaching time. This study identified that the situation can be improved through effective teacher training, in-service training, learner involvement, and effective planning.

Jacobi-Sobolev Orthogonal Polynomialsand Spectral Methods for Elliptic Boundary Value Problems

Generalized Jacobi polynomials with indexes α,β∈ R are introduced and some basic properties are established. As examples of applications,the second- and fourth-order elliptic boundary value problems with Dirichlet or Robin boundary conditions are considered,and the generalized Jacobi spectral schemes are proposed. For the diagonalization of discrete systems,the Jacobi-Sobolev orthogonal basis functions are constructed,which allow the exact solutions and the approximate solutions to be represented in the forms of infinite and truncated Jacobi series. Error estimates are obtained and numerical results are provided to illustrate the effectiveness and the spectral accuracy.

SYNTHESIS,CHARACTERIZATION AND ANTIMICROBIAL PROPERTIES OF 4-[(4-HYDROXYBENZYLIDENE)AMINO]PHENOL AND ITS POLYMER

The oxidative polycondensation reaction conditions of 4-[（4-hydroxybenzylidene） amino] phenol （4-HBAP） were studied with H2O2, air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90℃. The structures of the obtained monomer and polymer were confirmed by FT-IR, UV-Vis, 1H- and 13C-NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography （SEC） and solubility tests. At the optimum reaction conditions, the yield of poly[4-（4-hydroxybenzylidene amino） phenol] （P-4-HBAP） was found to be 48.3% （for H2O2 oxidant）, 80.5% （for air O2 oxidant） and 86.4% （for NaOCl oxidant）. According to the SEC analysis, the number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of P-4-HBAP was found to be 8950, 10970 g tool^-1 and 1.225, respectively, using H202; and l l610, 15190 g tool^-1 and 1.308 respectively, using air 02 and 7900, 9610 g mol^-1 and 1.216, respectively, using NaOC1. According to TG-DTA analyses, P-4-HBAP was more stable than 4-HBAP against thermal decomposition. The weight loss of P-4-HBAP was found to be 49.27% at 1000℃. The highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） values calculated from electrochemical measurement. Electrochemical energy gaps （Eg＇） of 4-HBAP and P-4-HBAP were found to be -5.46, -5.28; -2.26, -2.67; 3.20 and 2.61 eV, respectively. According to UV-Vis measurements, optical band gap （Eg） of 4-HBAP and P-4-HBAP were found to be 3.34 and 3.01 eV, respectively. Also, antimicrobial activities of 4-HBAP and P-4-HBAP were examined against selected some bacteria. The electrical conductivity of the polymer was measured after doping with iodine.