Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta Function and Modified Eddington, and second-order approximation methods with reference to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(F-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the Disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of approximation of the phase function of the RTE leads to a better precision in flux calculations. However, this approach may be limited to a certain order that has not been studied in this paper.

A NEW SIMULATING ALGORITHM FOR BALL MILLS--CONVERSION COEFFICIENT METHOD

The conversing relation among the Bond Work Index Wp specific output of mill and the energy efficiency of grinding were developed using dimensional analysis.The relations of which were proved and the value of the coversion coefficient i was also obtained using a new installed device for measuring grindability of ores.With the new simulating algorithm,the mill specifications,output and size distribution of griding products of industrial mills can be calculated based on laboratory measuring results.This algorithm is more accurate and simpler than any of the others.

Direct conversion of methane to methanol by electrochemical methods

A convenient method for methane(CH_(4))direct conversion to methanol(CH_(3)OH)is of great significance to use methane-rich resources,especially clathrates and stranded shale gas resources located in remote regions.Theoretically,the activation of CH_(4) and the selectivity to the CH_(3)OH product are challenging due to the extreme stability of CH_(4) and relatively high reactivity of CH_(3)OH.The state-of-the-art‘methane reforming-methanol synthesis’process adopts a two-step strategy to avoid the further reaction of CH_(3)OH under the harsh conditions required for CH_(4) activation.In the electrochemical field,researchers are trying to develop conversion pathways under mild conditions.They have found suitable catalysts to activate the C–H bonds in methane with the help of external charge and have designed the electrode reactions to continuously generate certain active oxygen species.These active oxygen species attack the activated methane and convert it to CH_(3)OH,with the benefit of avoiding over-oxidation of CH_(3)OH,and thus obtain a high conversion efficiency of CH_(4) to CH_(3)OH.This mini-review focuses on the advantages and challenges of electrochemical conversion of CH4 to CH_(3)OH,especially the strategies for supplying electro-generated active oxygen species in-situ to react with the activated methane.

Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

yb3＋/Dy3＋ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3＋, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3＋ and Dy3＋ is discussed.

Preparation of Hierarchically Trimodal-Porous ZSM-5 Composites through Steam-assisted Conversion of Macroporous Aluminosilica Gel with Two Different Quaternary Ammonium Hydroxides

This article presents a detailed structural study of a new spherical Mg Cl2-supported Ti Cl4 Ziegler-Natta catalyst for isotactic propylene polymerization, and researches on the relationship between catalyst structure and polymer properties. The spherical support with the chemical composition of CH3CH2 OMg OCH(CH2Cl)2 has been synthesized from a new dispersion system and is used as the supporting material to prepare Ziegler-Natta catalyst. The XRD analysis indicates that the catalyst is fully activated with δ-Mg Cl2 in the active catalyst. The far-IR spectrometric results confirm again the presence of δ-Mg Cl2 in the active catalyst. Textural property of the active catalyst exhibits high surface area coupled with high porosity. The high activity in propylene polymerization is mainly ascribed to the full activation and the porous structure of the catalyst. Scanning electron microscopy/energy dispersive spectrometer mapping results indicate a uniform titanium distribution throughout the catalyst particles. Particle size analysis shows that the catalyst has a narrow particle size distribution. The perfect spherical shape, uniform titanium distribution and narrow particle size distribution of the catalyst confirm the advantage of polymer particles production with less fines. The solid state 13 C NMR and mid-IR spectroscopic analyses indicate that there exists strong complexation between diisobutyl phthalate and Mg Cl2, which leads to the high isotacticity of polypropylene.

Catalytic Conversion of Alcohol to Corresponding Alkyl Chlorides

1-chloro-octane, 1-chloro-dedocane and 1-chloro-hexadecane are synthesized from the corresponding alcohols. The reactions are catalyzed by N, N-dimethyl formamide and dodecyltrimethyl animonium chloride, not only the reaction time has been reduced, but also the yield improved from 10%～20%.

Numerical Research of Mode Conversion in an Inhomogeneous Plasma

The linear mode conversion of electromagnetic waves in the hot, unmagnetized inhomogeneous plasma is studied numerically for different density profiles, and the dependence of the absorption coefficient on the incident angles and the wave frequencies are obtained for different electrons＇ temperature. The results show that the shapes of the density profiles and the electron＇s temperature create a certain effect on the coefficients of absorption, which reaches its peak value （about 50%） for appropriate parameters. Effective absorption occurs in a limited range of parameter q.

Geometric Conversion Approach for the Numerical Evaluation of Hypersin gular and Nearly Hypersingular Boundary Integrals over Curved Surface Boundary Elements

With the aid of the properties of the hypersingular kernels, a geometric conversion approach was presented in this paper. The conversion leads to a general approach for the accurate and reliable numerical evaluation of the hypersingular surface boundary integrals encountered in a variety of applications with boundary element method. Based on the conversion, the hypersingularity in the boundary integrals could be lowered by one order, resulting in the simplification of the computer code. Moreover, an integral transformation was introduced to damp out the nearly singular behavior of the kernels by the distance function defined in the local polar coordinate system for the nearly hypersingular case. The approach is simple to use, which can be inserted readily to computer code, thus getting rid of the dull routine deduction of formulae before the numerical implementations, as the expressions of these kernels are in general complicated. The numerical examples were given in three dimensional elasticity, verifying the effectiveness of the proposed approach, which makes it possible to observe numerically the behavior of the boundary integral values with hypersingular kernels across the boundary.

Synthesis and Characterization of IR Up-Conversion Material SrS∶Eu, Sm

Europium and samarium co-doped strontium sulfide (SrS∶Eu, Sm) infrared up-conversion phosphor was synthesized through calcining the precursor, which prepared by wet-method with strontium carbonate (SrCO_3), sulphur (S), europium oxide (Eu_2O_3) and samarium oxide (Sm_2O_3) as the starting materials, lithium fluoride (LiF) as the fluxing agent, at 750～1200 ℃ in carbon-reducing atmosphere. XRD analysis shows that SrS crystal structure is formed at 750 ℃, most completely at 1100 ℃. The IR up-conversion luminescence properties were characterized by excitation, emission, up-conversion excitation, up-conversion emission and thermoluminescence spectra. The spectral analysis associated with the physical model of up-conversion luminescence shows that the IR up-conversion luminescence is resulted from electron trapping process of Sm 3+ energy level. The thermoluminescence peak does not appear below 500 ℃ indicating the trapping energy level is appropriately deep, 800～1400 nm near infrared light can be the release light to realize up-conversion luminescence.

Electrokinetic flow and energy conversion in a curved microtube

Curved channels are ubiquitous in microfluidic systems.The pressure-driven electrokinetic flow and energy conversion in a curved microtube are investigated analytically by using a perturbation analysis method under the assumptions of the small curvature ratio and the Reynolds number.The results indicate that the curvature of the microtube leads to a skewed pattern in the distribution of the electrical double layer(EDL)potential.The EDL potential at the outer side of the bend is larger than that at the inner side of the bend.The curvature shows an inhibitory effect on the magnitude of the streaming potential field induced by the pressure-driven flow.Since the spanwise pressure gradient is dominant over the inertial force,the resulting axial velocity profile is skewed into the inner region of the curved channel.Furthermore,the flow rate in a curved microtube could be larger than that in a straight one with the same pressure gradient and shape of cross section.The asymptotic solutions of the axial velocity and flow rate in the absence of the electrokinetic effect are in agreement with the classical results for low Reynolds number flows.Remarkably,the curved geometry could be beneficial to improving the electrokinetic energy conversion(EKEC)efficiency.

Studies on Conversion of K in Potash Feldspar into Water-soluble Form

The studies for raising potash feldspar utilization ratio by physical, biological and chemical methods are carried out in laboratory and the results are presented. It is shown that calcinatory and biological methods have positive effects on conversion of K in potash feldspar into water-soluble form, but the conversion is low; chemical method can change most of insoluble potassium into available form, and might be significant in industry to some extent.

On the Conversion of Parts of Speech in English-Chinese Translation

Conversion refers to the transformation of parts of speech in some words while maintaining the original content unchanged in order to make the translated text sound smooth and fluent as well as more idiomatic in the target language. In E-C translation, conversion of pars of speech is one of the most important translation methods. Several different forms about conversion of parts of speech are introduced through analyzing the differences and usages between the two languages so that a better version in E-C translation can be got.

高质量保护与转化导向下高校专利申请前评估框架体系探索

立足专利申请之初以推动成果高质量保护与转化为出发点,重点围绕技术价值高度、市场需求前景、文件撰写质量、专利布局水平4个方向探索高校专利申请前评估框架体系。提出较完善的专利申请前评估框架、评估流程及方案及基于评估结果的分级管理模式,为高校专利申请前评估提供内容全面、切实可行的评估框架体系,为推动高校专利高质量申请与高效率转化提供助力。

单相并网储能双向变流器线性时间周期模型的稳定性分析

针对传统线性时不变模型无法描述储能双向变流器多频次谐波间交互耦合现象的问题,提出了一种单相并网储能双向变流器的线性时间周期模型,并进行稳定性分析。基于线性时间周期理论对单相并网储能双向变流器进行建模,得到非线性时间周期模型;围绕周期轨道将该模型线性化,得到储能双向变流器的线性时间周期时域模型;通过傅里叶展开推出了储能双向变流器的线性时间周期频域模型;利用李雅普诺夫第一方法分析比例积分控制器在不同参数下的储能双向变流器小信号模型的稳定性及稳定边界。MATLAB/Simulink仿真实验结果表明:建立的单相并网储能双向变流器的线性时间周期模型具有准确性和稳定性,稳定性边界正确。

基于X87指令集的浮点除法运算单元设计

基于X87指令集架构,在TSMC 65nm的工艺库下,采用SRT-16算法设计一种浮点除法运算单元。SRT-16算法主要是通过采用重叠商与余数计算部分的结构来进行优化处理,使得在原有传统算法SRT-4的基础上增加的电路面积较少,并且使得循环次数减少一半,并且在处理商的结果中引入商的飞速转换技术。通过对基于SystemVerilog自动对比平台的搭建,通过C对比模型,完成自动对比,加速验证的速度,进行功能覆盖统计,完成覆盖率100%。通过DC综合检测电路的时序情况,对电路进行时序优化,完成满足时序要求1.08ns,工作频率为900MHz。

两种沉积物粒度分析测试方法对比及转换关系

粒径分布(PSD)作为土体的基本物理性质之一,对土体的工程性质具有很大影响。目前,测量海洋沉积物PSD存在不同的方法,但不同方法量测结果的一致性和相互关系值得探讨。基于PSD沉降分析法与激光衍射法的测试原理,推导得出两种方法之间的联系,并提出了一种转换方法。采用上述两种测量方法对两种不同海域的深海沉积物进行PSD分析,依据转换方法对激光衍射法得到的PSD进行转换,并将转换后的结果进行分析。结果显示:沉降分析法与激光衍射法所得结果主要差距在于黏土、粉砂粒径的含量,且经转换后,两种测量方法得出的黏土、粉砂粒级的百分含量基本一致,检验了转换方法的可靠性。

蒸汽诱导法辅助相转化法制备疏水PDMS-PVDF微孔膜及其结构性能研究

采用蒸汽诱导法辅助浸没沉淀相转换法制备了硅橡胶-聚偏氟乙烯(PDMS-PVDF)疏水微孔膜并用于真空膜蒸馏NaCl水溶液,通过衰减全反射傅里叶变换红外光谱仪、X射线衍射仪、扫描电子显微镜、接触角测试仪对微孔膜的形貌结构和表面接触角进行表征和测试,研究了相对湿度对微孔膜结构和性能的影响。结果表明:随着相对湿度的增加,微孔膜表面接触角逐渐增加,孔隙率提高,平均孔径为(31±2)nm;截留率均达到99.9%以上,渗透通量先增加后降低;相对湿度为70%时制备的微孔膜渗透通量可达5.2kg/(m^(2)·h)。

电性源瞬变电磁法频-时转换的效果分析

电性源短偏移距瞬变电磁法是近年来新提出的固体矿产深部电磁探测方法之一,较传统的回线源瞬变电磁具有探测深度深、仪器轻便和分辨率高等优点。但该方法由于偏移距较短,距发射源较近,正演中的频-时转换会受到转换方法及其他工作参数的影响,进而直接影响探测结果,因此有必要开展频-时转换效果分析评价。通过对影响频-时转换的因素以及常用的四种频-时转换方法(Guptasarma线性滤波法、折线逼近法、余弦变换的数值滤波法和正弦变换的数值滤波法)在电性源短偏移距瞬变电磁正演响应计算中的对比,从计算时间和转换精度两方面分析了在不同条件下的转换效果,为一维及高维度的瞬变电磁正演计算提供频-时转换方法参考。对比结果表明:1)影响时间域瞬变电磁场正演计算(即频-时转换效果)的精度不仅和转换方法本身有关,而且也和偏移距及地下介质电阻率等参数有关;2)通过正演模拟,在低阻探测区采用折线逼近法与正弦变换的数值滤波法相对Guptasarma线性滤波法和余弦变换的数值滤波法转换精度更高,整体误差更小,而Guptasarma线性滤波法的计算速度最快,早期计算精度较高,晚期计算精度较差;在高阻探测环境中,采用折线逼近法计算精度和速度均相对较好,Guptasarma线性滤波法、正弦变换的数值滤波法及余弦变换的数值滤波转换效果均较差,特别是在晚期。因此,对于未知的探测区域,若实现高精度的电性源瞬变电磁正演计算,采用折线逼近法进行频-时转换相对效果最佳。

医疗机构中药制剂立项评价体系的构建及应用

目的以新药转化为导向,构建医疗机构中药制剂备案立项评价体系,以提高医疗机构中药制剂的申报成功率,为后期新药转化奠定基础。方法我院研发小组运用文献研究法,采用头脑风暴法列举并整理医疗机构中药制剂立项评价的相关要素,确定初拟指标体系;采用德尔菲法进行专家函询,确定评价指标,根据各指标的重要性评分占比计算权重,赋予具体分值,并采用该指标体系对2023年4-7月我院各科室申请备案的31个中药制剂进行评价。结果向17位专家进行了两轮函询,最终确定的医疗机构中药制剂备案立项评价体系包括理论依据、临床研究基础、药学基础、处方、临床价值5项一级指标,以及处方来源、中医理论、临床定位等17项二级指标,其中人用经验为一票否决项。基于上述指标体系,我院进一步完善了医疗机构中药制剂备案立项流程,并从2023年4-7月各科室申请备案的31个中药制剂中,遴选出8个评分≥65分的中药制剂拟进行开发。结论本评价体系客观、全面,可操作性强,适用于医疗机构中药制剂研发前的遴选。