THREE-DIMENSIONAL NUMERICAL SIMULATIONS OF THE EFFECTS OF ICE PHASE PROCESSES ON EVOLUTION OF CONVECTIVE STORMS

The numerical experiments on sensitivity of two types of convective storms to ice phasemicrophysical processes have been made by using a fully elastic three-dimensional cloud mod-el with a more detailed ice phase parameterization scheme. The simulations show that, ingeneral, inclusion of ice phase processes in the model leads to more intensive modelingstorms--the total latent heat released and the total precipitation increase obviously, the cloudtop rises, and the maximum ground precipitation rate is reached earlier. These effects of icephase processes can be much more significant in some relatively cold environments, in whichthey even modify the dynamic structures and life cycle of simulating storms. The mecha-nisms and favourable conditions of ice phase influences on storms are also discussed.     

POSSIBLE CAUSES OF COUNTERCLOCKWISE LOOP OF TROPICAL CYCLONES

The counterclockwise loop of a moving tropical cyclone in the model atmosphere is clearly shown in the numerical experiment by six sets of time integrations over periods longer than seven days in terms of a barotropical quasi-geostrophic model containing terms of environmental heating and dissipation. Numerical investigation is performed of the dependence of the abnormal path stability upon the computational domain size and the disturbance of the heat source, initial value and iterative precision, indicating that this type of path is a stabler form of motion for the cyclone in the model atmosphere. And the possible causes are presented.     

THE APPLICATION OF EMPIRICAL ORTHOGONAL FUNCTIONS TO NUMERICAL SIMULATION OF CLIMATE

According to the nonlinear basic theory that a forced dissipative nonlinear system in a higher dimensional state space can be evolved into an attractor set of the descending dimension, a new method of reducing the degrees of freedom of the general circulation model (GCM) is given. The concrete way of it is: the time-dependent integral series of the model is decomposed through empirical orthogonal functions (EOFs), therefore the small number of the degrees of freedom supporting the attractor set of GCM can be formed, and then a simplified model can be derived when the EOFs are used as basis. The numerical simulation experiment has been done by using a theoretical model, and we are sure that the feasibility and effectiveness of the method can be proved.     

用直接数值模拟对移动颗粒层除尘的研究及实验对比

利用气固两相流数值模拟计算模型，分别采用不同粒径的移动颗粒层过滤除尘器，对不同粒径粉尘颗粒的碰撞次数进行统计，并对移动床除尘中过滤介质尺寸与粉尘粒径尺寸之间的相互选择性进行了初步研究。模拟计算了在同一风速下碰撞次数与粉尘粒径以及移动层颗粒径之间的关系。计算统计的结果与实验结果对比发现，二者存在定性上的一致。结果表明，在移动床过滤除尘器中不同粒径的过滤层对不同粒径尘粒具有明显的选择性。     

硬木热解过程中颗粒内部二次反应的数值研究Ⅱ.数值模拟结果

为了研究生物质（硬木）热解过程中颗粒内部的二次反应，对流化床环境下单颗粒生物质热解模型进行了求解。计算针对典型大颗粒和典型小颗粒在流化床反应器反应条件下的热解过程，对不同大小颗粒内部各种产物的生成、消耗、积累以及逃逸行为进行了定量描述。计算结果表明：对于直径为2mm的小颗粒，颗粒内二次裂解的份额可以忽略，但是对于直径10mm的大颗粒，热争过程中有超过20%的一次焦油参加了颗粒内部二次反应，颗粒内二次裂解显著地改变了热解产物分布，改变了热解产物的品质。     

结晶型聚合物注塑过程冷却模型的数值模拟

对HDPE平板状注塑件的冷却过程进行了数值模拟 .基于小分子结晶性物质的冷却模型 ,建立了固相、液相及固液相界面的控制方程 ,方程中引入热焓E和参数T 后 ,将带耦合条件的热传导方程转变为非线性抛物型方程 ,按控制容积法将其离散后 ,用数学软件Matlab获得了PE的三维温度场 ,这为探讨带相转变的热传导问题提供了一种有效的数值方法 .通过对制件芯层温度变化的模拟值与实验值的比较 ,比较了不同相变温度下理论结果的准确性 ,结果表明 ,在引入一定过冷度后 ,将相变温度定义在低于平衡熔点以下时 ,该方法的模拟值具有更好的准确性 .同时 ,模型分析了不同工艺条件对制件芯层冷却过程的影响 ,通过相变平台出现的先后以及终止时间的不同 ,说明充模温度主要影响熔体阶段的冷却以及相变出现的先后 ,而模具温度主要影响固体阶段的冷却以及相变平台终止的先后 .     

A NUMERICAL EXPERIMENT FOR EFFECTS OF OZONE HEATING ON GENERAL CIRCULATION

An ozone conservation equation is added to the global nine-layer general circulationmodel to simulate the heating effect on the upper atmosphere due to the absorption of theultraviolet part of solar radiation by ozone and the changes of temperature, pressure andwind fields caused by ozone heating. The experiment shows that the heating rate by ozoneis much larger than that by other elements such as water vapour in stratosphere. Thetemperature distribution and strength of zonal wind in tropopause and above calculated withozone effect are much different from the results simulated without ozone. The ozone heatingaffects not only the zonal wind but also the meridional wind, so that the Walker Circulationand Hadley Cell are all changed accordingly. Besides, it can be seen that the influences ofozone on the meteorological elements are small in troposphere, while it still makes apparentlyresponse near the surface. Especially, it is much larger above the land than above the ocean.     

THE EFFECTS OF PORPHYRIN STRUCTURE AND AGGREGATION STATE ON PHOTOSENSITIZED PROCESSES IN AQUEOUS AND MICELLAR MEDIA

The efficiency of several porphyrins at 10 μM and 83 μM as sensitizers of the photooxidation of 0.1 mM tryptophan and histidine via a singlet oxygen-mechanism was studied in pH 7.4-buffered aqueous solutions and in aqueous dispersions of Triton X-100 micelles. The porphyrins were either solubilized in the bulk aqueous medium or associated with the micellar phase, whereas the amino acids were always located in the aqueous phase. With those porphyrins, such as uroporphyrin I, meso-tetra (4-sulfonatophenyl)porphine, meso-tetra(4-carboxyphenyl)porphine and meso-tetra)N,N,N-trimethylanilinium)porphine, which are > 98% monomeric in both media, the efficiency of histidine photooxidation was independent of the site of O₂(¹Δ_g) generation, as shown by the closely similar values for the photooxidation rate constant and oxygen-consumption quantum yield in the presence and absence of Triton micelles; the same indications were provided by photokinetic experiments with tryptophan. Actually, laser flash photolysis studies showed that the micelle-incorporation of the above mentioned porphyrins brought about only minor changes in their photophysical properties, including the relative yield of O₂(¹Δ_g) generation. On the other hand, hematoporphyrin IX, its Zn²⁺-complex, and coproporphyrin III are largely aggregated in homogeneous aqueous solution; their incorporation into Triton micelles caused an increase of the triplet quantum yield and an enhancement of the oxygen-consumption quantum yield and photooxidation rate constant for both histidine and tryptophan. The lower photosensitizing efficiency of aggregated porphyrin species in comparison with the corresponding monomeric porphyrin was confirmed by measuring the initial rate and quantum yield of oxygen consumption upon irradiation of 1 mM histidine and tryptophan in the presence of different hematoporphyrin concentrations within the 0.3-100μM range.     

苯甲醛及其衍生物对铈离子存在下丙烯酰胺聚合的影响

<正> 虽然Santappa等早已报道Ce~(4+)(高氯酸铈)/甲醛体系能引发丙烯腈(AN)、甲基丙烯酸甲酯(MMA)的聚合,但对醛的活性以及参与引发单体聚合的自由基都未有详细报道,近来孙燕慧等发现脂肪醛能显著促进Ce~(4+)(硝酸铈铵CAN)引发丙烯酰胺(AAM)的聚合,而且醛的活性远大于相应的醇。至于芳香醛对于Ce~(4+)引发烯类单体的聚合的影响也未见详细报道。本文扼要报道苯甲醛(BA)及其衍生物对-硝基苯甲醛(PNBA)、间-硝基苯甲醛(MNBA)、间-溴苯甲醛(MBBA)、对-氯苯甲醛(PCBA)对Ce~(4+)(CAN)存在下丙烯酰胺聚合的影响,测定了其聚合速率,以UV吸收光谱、ESR波谱测定     

吸附柱出口温度随时间的变化规律及其数值模拟

在不同温度 (15℃、20℃、25℃) 下,测试了活性炭C40/4吸附有机气体丙酮的吸附热引起吸附柱出口温度的变化.理论分析了吸附过程的能量守恒模型,在其他物质守恒,动量守恒和吸附平衡数学模型的基础上,采取有限差分方法,并借助计算软件ATHENA VIUAL WORKBENCH对模型进行了数值解.探讨了物质轴向扩散系数,吸附热对吸附柱出口温度随时间变化规律的影响,发现吸附质轴向扩散系数是一个很小的数,可忽略不计,从而简化了模型.数值计算结果与实验结果能很好地相吻合.为获得吸附过程中有效传热系数提供了有效的解决方法,并为吸附过程的设计、预测和优化提供支持.     

磷酸三丁酯对环已烷辐解的抑制

报导了磷酸三丁酯(TBP)对环己烷辐解的抑制效应。通过观察TBP对环己烷主要辐解产物氢气、环己烯、二环己烷的产额的影响和结合TBP-环己烷二元体系激发单重态敏化实验的结果。发现: TBP对环己烷辐解的抑制可分为两个过程, a)激发能传递, b)电子捕获。求得环己烷偕离子对产额为3.8, TBP捕获电子的反应系数为6.3 L·mol~(-1)。     

SEPARATION OF IRON AND MANGANESE IN THE EARLY DIAGENETIC PROCESSES AND ITS MECHANISM OF BIOGEOCHEMISTRY

Study shows that the reduction of iron (Fe~(3+)) and manganese (Mn~(4+)) in modern sedi-ments and the diffusive flux of the Mn~(2+) from the pore water into the overlying waterare mainly controlled by bacteria, and the distribution of the bacteria is believed to beaffected strongly by the sedimentary environment. It is the diffusive fluxes between Fe~(2+)and Mn~(2+) that lead to the separation of iron and manganese in the modern sediment at theChangjiang Mouth and near the shore. The level of the separation decreases with theincrease of the overlying water salinity and increases from the surface to the depth. Thismechanism has given a new explanation why manganese is concentrated in sediments onthe oceanic floor of ferromanganese-rich nodules.     

THE SIMULATION AND OPTIMIZATION OF GRADIENT ELUTION HPLC

The movement of a particular component along an HPLC column is studied on the ba-sis of equilibrium equations. Numerical simulation of multi--step gradient elution HPLC isperformed by means o? a personal computer program. The location x, as a fraction of thecolumn length, for a given time t o? each compound is calculated, the velocity and corre-sponding acceleration are given as well. Diagrams for x,dx/dt and d~2x/dt~2 versus t display themovement process of the different components along the HPLC column during gradient elu-tion. The prediction of the retention time and peak width, and the optimization for the multi-step gradient elution HPLC are all based on such simulation and the molecular structure ofthe. components is separated as well.     

THE INFLUENCE OF STRUCTURAL EFFECTS ON THE COMPLEXING ABILITY OF CROWN ETHERS

Abstract

Simple regression including interaction energies of the cation-ligand systems explains to some extent the variability in logarithms of stability constants of complexes formed by a series of nine 18-crown-6 ethers with potassium cations in methanol. The atomic charges were calculated for energy minimized structures, found during molecular dynamics computations. In order to mimic the residual solvation of complexed cations, two CH₃OH molecules were incorporated above and below the macrocyclic plane. Polarization effects of the metal cation on the resulting atomic charges were considered in calculations and found to be crucial for satisfactory correlations with experimental data.     

用直接数值模拟方法对流化床内颗粒运动区域的研究

采用直接数值模拟技术 ,跟踪离散颗粒场中的每一个颗粒 ,对不同直径和密度的颗粒在流化床内的流化运动区域进行了探讨研究。结果表明 ,不同直径和密度的颗粒在流化床内的流化区域有显著的差异。在颗粒密度相同 ,颗粒直径取正态分布时 ,小颗粒在床内大部分集中在床层的上方 ,大颗粒的运动密集区域在床的下半部分。当颗粒直径相同而密度取正态分布时 ,轻颗粒的活动范围趋向于床层的上方 ,重颗粒的运动区域分布与轻颗粒相反。还发现 ,粒径变化对颗粒流化区域的影响大于密度变化所造成的影响。     

类蛋白质分子扩散系数的模拟计算

蛋白质分子是一类比较特殊的高分子，一方面它的性质与氨基酸序列密切相关，另一方面其二级结构（如α螺旋以及β折叠等）极大地影响着它的性质．另外它的内部结构又非常紧密，与一般的高分子链完全不同．同时随着计算机技术的发展，计算机模拟日益作为一种有效的手段广泛应用于高分子科学的研究．但是由于蛋白质分子比一般的高分子结构更加复杂，如氨基酸之间有复杂的互相作用等，因此对蛋白质性质的研究往往建立在简化模型的基础上，如基于格点的HP紧密高分子模型等．虽然建立在格点模型上的蛋白质分子和真实的蛋白质分子存在着一定的差异，但基本上能体现蛋白质分子的主要特征，因此把这一类分子称为类蛋白质分子．     

泡沫的稳定性及液晶对它的影响

泡沫体系的表面张力、粘度,表面粘度以及液晶相的存在对泡沫的稳定性皆有影响。消泡剂可改变上述性质。本文报导聚氧乙烯辛基酚(TritonX-100),十二烷基硫酸钠(SDS),油酸三乙醇胺(TEAOL)和卵磷脂等起泡剂在均相溶液及有液晶存在时产生泡沫的稳定性,观察硅油的消泡作用。     

Monte Carlo模拟方法研究管道受限对高分子链缠结的影响

采用基于格子模型的Monte Carlo模拟方法,考察了链长分别为30和250的线形高分子在管道内受限状态下的尺寸及扩散性质.结果表明,当线形高分子的链长低于其缠结链长时,其受限条件下高分子的性质随受限程度的变化而单调变化;而当线形高分子的链长大于缠结链长时,高分子的性质表现出非单调性,进而说明受限具有一定程度的解缠结...     

半结晶聚合物注射成型中结晶动力学的数值模拟

对半结晶聚合物注射成型过程及其结晶过程进行偶合模拟,分析了二者的相互影响.具体是在注射成型数值模拟中考虑结晶动力学效应,分别在本构方程、能量方程及材料物性参数方程中引入反映结晶效应的参数;同时在结晶动力学计算中考虑流动诱导效应,从能量的角度提出并使用修正的动力学模型,用材料流动过程的耗散能表征流动对结晶的影响.通过对等规聚丙烯(iPP)和聚对苯二甲酸乙二醇酯(PET)两种半结晶聚合物注射过程模拟结果的分析比较,证实成型过程具有加速结晶的作用.同时,材料的结晶也对注射成型加工过程,尤其是保压与冷却过程的温度场分布有较大的影响.     

K对Mn—Co—O的结构及氧化活性的影响

利用XRD,TPD,TFD-MS及催化氧化反应等实验技术,研究了K对Mn-Co-O的结构及氧化活性的影响。XRD结果表明,Mn-Co-O系已形成反尖晶石型的MnCo_2O_4结构;K-Mn-Co-O系中除MnCo_2O_4型结构外,还有新相KMnO_2存在。根据O_2的TPD-MS及吡啶的TPD结果,Mn-Co-O中添加适量的K能提高供氧活性和增加供氧数目,但酸中心数目减少,强度降低。K对Mn-Co—O催化剂氧化活性的影响随反应物分子结构的不同而异,对乙酸乙脂、苯甲酰氯等极性有机物的完全氧化反应,K能提高氧化活性,但对苯、正己烷等非极性有机物的完全氧化反应,K使其活性降低。