NUMERICAL SIMULATION OF BENARD CONVECTION IN A CLOSED RECTANGLE (Ⅰ)——TWO-DIMENSIONAL CASE

In the paper, a finite differential numerical model is proposed for Benard convection ina non-slippery closed rectangle. By this model, we have discussed the bifurcation character-istics of two-dimensional Benard convection when Prandtl number is 1. The computed re-sults show that if the Rayleigh number Ra≥1.75×10~5, the Benard convection is unsteady andirregular, and that in the transient region of flow pattern, the changing rate of the Nusseltnumber Nu to Ra, dlgNu/dlgRa, is rather smaller than that in the non-transient region.Moreover, in the paper, we have analysed the relation between the shrinking rate of thephase flow and each term in the governing equations of Benard convection. And further,we have developed a new method to calculate the pressure gradient.     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF TROPICAL CYCLONE AND THE EFFECTS OF RADIATIVE PROCESSES ON IT

In this paper, a three-dimensional primitive equation numerical model includingvarious physical processes is constructed. Using this model, the development and thestructure of the tropical cyclone (typhoon) are first successfully simulated. Then theeffects of radiative processes on the development of the cyclone are investigated. Theradiative processes and their parameterization include long wave, short wave radiationand cloud type and cloudiness respectively. The results show that the tropical cyclonewill develop earlier and more quickly after the effect of radiative processes isincorporated, but the differences in intensity between the two cases with and withoutradiative processes at the final state are not evident. Only at the developing stage hasthe cyclone affected by radiation a sharper decrease in the surface pressure, a strongerwind and upward motion. a more obvious eye and eyewall, etc. All the results showthat the radiative processes are important in the earlier development stage of thetropica     

NUMERICAL SIMULATION OF MORPHOLOGY OF POLYMER CHAIN COILS IN COMPLEX FLOWS

A new coupled finite element formulation is proposed to calculate a conformation tensor model in two complex flows： a planar contraction flow and a planar flow around a symmetrically placed cylinder. The components of conformation tensor are first computed together with the velocity and pressure to describe the change of morphology of polymer chain coils in flow fields. Macroscopic quantities of viscoelastic flow are then calculated based on the conformation tensor. Comparisons between the numerical simulations and experiments for stress patterns and velocity profiles are carried out to prove the validity of the method.     

A THEORETICAL ANALYSIS OF LOTKA''''S MODEL IN CLOSED SYSTEM

In this paper, the Lotka's model in closed system has been discussed in detail. Considering the consumption of reaction reagent, this model is analysed in accordance with the first order harmonic wave approximation and digital calculated by using the microcomputer.For the various initial conditions (according to, approaching, deviating from and deviating far from the Lotka's steady-state condition) the corresponding chemical oscillation behaviours are studied. The rules in connection with the time dependence of corresponding concentrations and the reaction trajectories in the relative component concentration phase space are obtained. The effectual regions in regard to the first order harmonic wave are examined. The relative results may be used to explain some important chemical oscillation phenomena, such as the sustained, damped and exploded oscillations.     

A STUDY ON NUMERICAL SIMULATION OF CLOUD MERGERS AND INTERACTIONS

A two-dimensional, time-dependent and warm cumulus cloud model has been used to investigate problems concerning cloud merger and interaction. The results of numerical experiment show: (ⅰ) Two clouds formed at the same time have influence on each other at a shorter distance;on one hand, it is possible that they merge with equal intensity, and on the other, it is impossible that they merge with unequal intensity;in case of quite different intensities the weak cloud is depressed and the strong cloud accretes. (ⅱ) Two clouds, developing with timing difference at a shorter distance and in the same growth stages, may merge. (ⅲ) The merged cloud develops more violently than the unmerged and produces more rainfall. (ⅳ) Cloud merger results from the action of a horizontal pressure gradient accompanied with a circulation field in the lower layer of clouds.     

COMPUTER SIMULATION OF A SINGLE POLYMER CHAIN IN DIFFERENT SOLVENTS

In the present paper, the behavior of a single polymer chain under various solvent conditions was modeled by self-avoiding walks (SAW) with nearest neighbors attraction Δε on a simple cubic lattice. Determination of the θ-condition wasbased on the numerical results of the mean square radius of gyration and end-to-end distance. It was found that at the θtemperatue Δε/kT equals -0.27. The exponents a in the Mark-Houwink equation with different interaction parameters areconsistent with the results of experiments: under θ-condition, a = 0.5, and for a good solvent α= 0.74-0.84, respectively.     

OBTAINING PRECISE CRITICAL DRAW RATIO OF DRAW RESONANCE IN MELT SPINING BY NUMERICAL SIMULATION OF DIFFERENCE EQUATIONS

Direct difference methods have been used to solve the simultaneous non-linear partial differential equations for melt spinning without recourse to linearisation or perturbation approximation. The stability of each difference schemes was studied by error analysis using the Taylor series, and by comparison of the results obtained from numerical simulation with the logical value in melt spinning. It is found that computation with 19 digit long double precision has significantly simplified the stability problem of difference equations. Using this method, the precise critical draw ratio of draw resonance in an isothermal and uniform tension spinning of Newtonian fluids can be obtained in between 20.218 and 21.219, a figure consistent with 20.218 which was obtained by a linear perturbation approximation method by Kase and Denn. It thus has paved the way to computation of full information for unsteady melt spinning processes using the difference method.     

A MATHEMATICAL SIMULATION OF EARTHQUAKE SEQUENCE IN NORTH CHINA IN THE LAST 700 YEARS

A scheme in Fig. l is used to simulate the earthquake sequence in North China in the last 700 years. With a postulated fault system, a mechanical parameter distribution and suitable boundary tractions, the stress field is computed by finite element method in plane strain. The fault zones are treated as elastic-perfectly plastic medium which flows according to Coulomb's criterion and its associated flow rule. An earthquake is simulated by lowering the static coefficient of friction to a kinetic one at the epicenter to cause a slip there and arrived at a new equilibrium position. The differences in displacement, stress, etc. before and after the lowering are considered to be due to the earthquake and compared to observations. After adjustments of parameters and boundary tractions, the results are satisfactorily compared with the major earthquake sequence of 14 events M_s≥7 and regions of seismic risk in the last 700 years. Possible localities of future earthquake risk after the Tangshan earthquake and ef     

A STUDY OF PACKING STRUCTURE OF POLY(P-PHENYLENE BENZOBISTHIAZOLE)BY MOLECULAR SIMULATION

Molecular simulation technique was used in an examination of the possibilities of chain packing inthe crystalline state for poly(ρ-phenylene benzobisthiazole).It has been found that one reason of hardlyforming very ordered crystal of the polymer is the existence of so many stable positions of interchaininteraction along chain axis.     

TRACE METALS IN VANDA LAKE IN ANTARCTICA——A VERTICAL MIGRATION MODEL OF TRACE METALS IN CLOSED BASIN

Vanda Lake, a typical dimictic CaCl_2 type salt lake, is located in the Wright Valley inAntarctica. Based on the chemical and physical features of the salt lake water, the authorsdiscussed the vertical geochemical distribution of Fe, Mn, Pb, Cr, Cu, Co, Ni, Cd in the lake,and their vertical migration in lake waters, and have tried to set up a model of vertical mi-gration of these trace elements in the water of a closed chloride type salt lake.     

APPLICATION OF COMBINATION PRINCIPLE FOR CLOSED NETS IN n k(k≥4) PHASE MULTISYSTEMS——ESTABLISHMENT OF COMPLETE SYSTEMS OF CLOSED NETS FOR UNARY SIX-PHASE (n 5) MULTISYSTEMS

Applying the combination principle for closed nets in n k(k≥4) phase multisystems, the author has derived the complete systems of closed nets of unary six-phase(n 5) multisystems. Every typical closed net involves exclusively eight invariant points. Two topologically distinct configurations of the typical closed nets have been generated from two different ways of combination, and hence, two distinct representation polyhedra have been constructed. On the basis of these configurations or polyhedra, the author has rederived all the 16 basic forms of phase diagrams given by Kujawa et al.     

AN EPIDEMIC SIMULATION MODEL OF STRIPE RUST (Puccinia striiformis) ON SLOW RUSTING CULTIVARS OF WHEAT (Ⅱ)

The Slow Rusting Epidemic Simulation Model (SRESMI) was built based on the resistance com-ponent data obtained from field experiments. In the preliminary validation of the model, the simulatedepidemics basically conformed to the observed ones and the structure of the model seemed to be basicallycorrect. Among the resistance components, infection frequency, sporulation capacity and the lesion expan-sion rate played the most important role in the slow rusting epidemic, while the latent and infectiousperiods did the less and the least, respectively. This model may be useful for the exploration of slow-rusting breeding and the evaluation of the potential effectiveness of slow-rusters in practical cultivationunder different epidemic pressures.     

A NOVEL EOR POLYMER (Ⅱ)——INVESTIGATION ON IN-SITU GELATION OF SMRF SYSTEM IN BEREA CORE

In-situ gelation of aqueous sulfomethylated resorcinol formaldehyde (SMRF) system inBerea core has been investigated. Two sets of displacement experiments were conducted with thissystem (containing 5% NaCl, 0. 036% CaCl_2. 2H_2O). The brine permeabilities of the coreswere reduced significantly from about 600 to 0.1 md. The in-situ gelation in Berea core occurreda little bit earlier than gelation anticipated from bulk test in the experiments. The gel time waseasier to control at initial pH between 6 and 8. During injection of SMRF system, the apparentviscosity was less than 1 mPa·s at 41℃.     

SIMULATION OF THE SEISMIC TECTONIC STRESS FIELD IN NORTH CHINA

The paper reviews several methods of simulation used in this country to recover currenttectonic stress field related to earthquake occurrence in North China. The aim is to evaluatethe degree of seismic risk around Beijing area. The methods used are computational ormathematical simulation by the finite element method and experimental or physical simulationby the photoelastic method and the grid method. The results obtained by these methods arebriefly described. Most simulations indicate that Beijing is not a region of seismic risk.     

KINETICS OF IRREVERSIBLE MODIFICATION OF ENZYME ACTIVITY IN A SYSTEM OF COUPLED ENZYME ASSAY (Ⅱ)——BOTH PRIMARY AND AUXILIARY ENZYMES MODIFIED BY REAGENT Y

Following the previous paperr, we examined the kinetics of the irreversible modification of enzyme activity in coupled assay when the modifier reacted with both primary and auxiliary enzymes. It was shown that Tsou's kinetic method can also be used in the present situation in some conditions.     

A NEW PEAK (T_4) IN THE ~(13)C-NMR SPECTRUM OF POLYBUTADIENE

A new peak at 39.0 ppm in the ~(13)C-NMR spectrum of polybutadiene (PBD) was discovered. This peak is assigned to the fourth peak (T_4) of trans-1,4-sequence marked with an asterisk as shown in Fig. 3 in the text.The occurrence of T_4 carbon nuclei is strongly affected by their neighboring 1,2-units. So long as both contents of trans-1,4- and 1,2-units attain their proper amounts the peak (T_4) with appear in the ~(13)C-NMR spectrum of PBD.     

A STUDY OF SILICA-SUPPORTED CROSS-LINKED POLY (MALEIC ACID-CO-STYRENE)-PLATINUM COMPLEX IN THE HYDROGENATION OF p-CRESOL

A silica-supported cross-linked poly(maleic acid -co- styrene)-platinum complex (PMS-Pt) has been prepared and found to be active in the hydrogenation of p-cresol undermild conditions (303-323K, 1.01×10~5Pa). In this hydrogenation system water servesas a solvent and p-cresol can be converted to 4-methylcyclohexanol quantitatively via4-methylcyclohexanone as intermediate.     

APPLICATION OF NOETHER'S THEOREM IN CHEMISTRY (Ⅲ)——THE SKILL IN REACTION OPERATOR

IN the previous papers of the author's,the elementary reactionoperator concerning point group was discussed.In thispaper,more complex reaction operators will be analysed.Byusing the skillin reaction operator,the electrocyclic and cy-cloaddition reactions are illustrated.     

EFFECTS OF CONFORMATION OF POLYMER LIGANDS IN COPPER(Ⅱ) COMPLEXES ON CATALYLIC ACTIVITIES AND MECHANISM OF OXIDATIVE COUPLING OF β-NAPHTHOL

Copper(Ⅱ) complexes of sericin, chitosan, 6-and 2-aminodeoxystarch were used as catalysts in oxidative coupling of β-naphthol, the effects of conformation of the polymer ligands in these complexes on activities of the catalysts and mechanisms of the reaction were studied. It was found that if the catalysts react with the substrate by mechanism similar to the enzymic catalysis they must be composed of polymer ligands with highly coiled, especially with densely helicoidal, conformations. While catalysts composed of loosely coiled or helicoidal hgands react with the substrate through molecular collision and have relatively lower activities only. Under nitrogen, catalysts from sericin and chitosam reacting with β-naphthol give optically active β-binaphthol, rotating polarized light to right, but the stereoselectivities are rather low.     

SYNTHESIS AND CATALYTIC PROPERTY OF POLYSTYRENE SUPPORTED PHENYLALANINE SCHIFF BASE COMPLEX OF Mn(Ⅱ) IN AEROBIC OXIDATION OF CYCLOHEXENE

1. INTRODUCTION The partial oxidation of alkenes (forming acids, aldehydes and alcohols) is of considerable interest to the chemical industry. In most cases, more than one oxygenated product is formed from a given starting material and all products are susceptible to complete oxidation to carbon dioxide and water [1]. As mimetic oxygen carrier or oxidation catalyst, metalloporphyrins have been widly studied [2~7]. Among the non-porphyrin systems, the manganese complexes of Schiff base are…