TENSILE STRENGTH OF RANDOM ORIENTED SHORT FIBER COMPOSITE

This paper shows a calculation model and a method for predicting the tensile strength of the random distributed short fiber composite.On the basis of Renjie Mao's model,the longitudinal tensile strength of the aligned short fiber composite is formulated.Considering the transverse tensile strength and in plane shear strength of the unidirectional fiber composite,and the stress transformation relations of two couples of axes,the stress of the unidirectional fiber composite when it is loaded at an arbitrary angle is obtained.With the aid of an equivalence relation,the calculation formulation of the tensile strength of the random short fiber reinforced composite is deduced.

Application of 1D/3D finite elements coupling for structural nonlinear analysis

An element coupling model (ECM) method was proposed to simulate the global behavior and local damage of a structure.In order to reflect the local damage and improve the computational efficiency,three-dimensional (3D) solid elements and one-dimensional (1D) beam element were coupled by the multi-point constraint equations.A reduced scale 1?8 model test was simulated by the ECM and a full three dimensional model (3DM) contrastively.The results show that the global behavior and local damages of ECM agree well with the test and 3DM.It is indicated that the proposed method can be used in the structural nonlinear analysis accurately and efficiently.

CFD-PBE simulation of a bubble column in OpenFOAM

A general CFD-PBE(computational fluid dynamics-population balance equation) solver for gas–liquid poly-dispersed flows of both low and high gas volume fractions is developed in OpenFOAM(open-source field operation and manipulation) in this work. Implementation of this solver in OpenFOAM is illustrated in detail. The PBE is solved with the cell average technique. The coupling between pressure and velocity is dealt with the transient PIMPLE algorithm, which is a merged PISO-SIMPLE(pressure implicit split operator-semi-implicit method for pressure-linked equations) algorithm. Results show generally good agreement with the published experimental data, whereas the modeling precision could be improved further with more sophisticated closure models for interfacial forces, the models for the bubble-induced turbulence and those for bubble coalescence and breakage.The results also indicate that the PBE could be solved out the PIMPLE loop to save much computation time while still preserving the time information on variables. This is important for CFD-PBE modeling of many actual gas–liquid problems, which are commonly high-turbulent flows with intrinsic transient and 3 D characteristics.

Functional Integrals and Quantum Fluctuations on Two-Dimensional Noncommutative Space-Time

The generalized Thirring model with impurity coupling is defined on two-dimensional noncommutativespace-time,a modified propagator and free energy are derived by means of functional integrals method.Moreover,quantum fluctuations and excitation energies are calculated on two-dimensional black hole and soliton background.

Theoretical analysis of fluid mixing time in liquid-continuous impinging streams reactor

The mixing time of impact zone in liquid-continuous impinging streams reactor(LISR) is theoretically calculated by empirical model and modern micromixing model of the fluid mixing process, and the variation laws of macromixing time and micromixing time are quantitatively discussed. The results show that under a continuous and stable operating condition, as the paddle speed increases, the macromixing time and micromixing time calculated by the two models both decrease, even in a linkage equilibrium state. Simultaneously, as the paddle speed increases, the results figured by the two models tend to be consistent. It indicates that two models both are more suitable for calculation of mixing time in high paddle speed. Compared with the existing experimental results of this type of reactor, the mixing time computed in the speed of 1500 r/min is closer to it. These conclusions can provide an important reference for systematically studying the strengthening mechanism of LISR under continuous mixing conditions.

Calculation of thermodynamic properties in liquid phase for ternary Al-Ni-Zn alloys

The results of the calculation of thermodynamic properties in liquid state for ternary Al-Ni-Zn alloys using the newest version of the general solution model for thermodynamic prediction are presented. Nine sections with different molar ratios of Ni to Zn, Zn to Al and Al to Ni were investigated in a temperature interval of 1800-2000 K. Partial and integral molar thermodynamic properties in liquid phase for the Al-Ni-Zn ternary system are determined and discussed.

A Modified Mixing Rule for PSRK Model and Application for the Prediction of Vapor-Liquid Equilibria of Polymer Solutions

To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.

Mapping Soil Organic Carbon Stocks of Northeastern China Using Expert Knowledge and GIS-based Methods

The main aim of this paper was to calculate soil organic carbon stock(SOCS) with consideration of the pedogenetic horizons using expert knowledge and GIS-based methods in northeastern China.A novel prediction process was presented and was referred to as model-then-calculate with respect to the variable thicknesses of soil horizons(MCV).The model-then-calculate with fixed-thickness(MCF),soil profile statistics(SPS),pedological professional knowledge-based(PKB) and vegetation type-based(Veg) methods were carried out for comparison.With respect to the similar pedological information,nine common layers from topsoil to bedrock were grouped in the MCV.Validation results suggested that the MCV method generated better performance than the other methods considered.For the comparison of polygon based approaches,the Veg method generated better accuracy than both SPS and PKB,as limited soil data were incorporated.Additional prediction of the pedogenetic horizons within MCV benefitted the regional SOCS estimation and provided information for future soil classification and understanding of soil functions.The intermediate product,that is,horizon thickness maps were fluctuant enough and reflected many details in space.The linear mixed model indicated that mean annual air temperature(MAAT) was the most important predictor for the SOCS simulation.The minimal residual of the linear mixed models was achieved in the vegetation type-based model,whereas the maximal residual was fitted in the soil type-based model.About 95% of SOCS could be found in Argosols,Cambosols and Isohumosols.The largest SOCS was found in the croplands with vegetation of Triticum aestivum L.,Sorghum bicolor(L.) Moench,Glycine max(L.) Merr.,Zea mays L.and Setaria italica(L.) P.Beauv.

Characteristic of Drop Coalescence Resting on Liquid-Liquid Interface

The trajectory model of dispersed phase drops and the model of basic flow for drop motion between two inclined parallel plates are derived with the optimized calculation. The analytical results of direct numerical simulation indicate that the basic flow plays an important role in the drop coalescence on liquid-liquid interface. In the stratified two-phase flow field, the smaller droplets are difficult to drain the thin continuous film between the approaching droplets and bulk interfaces and eventually immerse into the trickling film to yield coalescence. They almost attain the velocity of their local surroundings. Moreover, the basic flow exerts a dominant influence on the motion of smaller droplet. The smaller droplets are easily entrained by the basic flow. On the contrary, the larger drop presents advantageous characteristics of coalescence due to its high velocity. The range of 0.3 mm < δR≤ 0.75 mm is the advantageous drop coalescence condition since the rapidly varied velocity and its first derivative theoretically cause the forces acting on a drop to become imbalanced. On the other hand, the thin layer of the continuous phase drained from the interval between the drops and trickling film should not be neglected in the calculation of shearing force since it is important for drop rotation. The drop rotation is an indispensable factor in coalescence.

Synthesis of fractal geometry and CAGD models for multi-scale topography modelling of functional surfaces

In order to support the functional design and simulation and the final fabrication processes for functional surfaces,it is necessary to obtain a multi-scale modelling approach representing both macro geometry and micro details of the surface in one unified model.Based on the fractal geometry theory,a synthesized model is proposed by mathematically combining Weierstrass-Mandelbrot fractal function in micro space and freeform CAGD model in macro space.Key issues of the synthesis,such as algorithms for fractal interpolation of freeform profiles,and visualization optimization for fractal details,are addressed.A prototype of the integration solution is developed based on the platform of AutoCAD's Object ARX,and a few multi-scale modelling examples are used as case studies.With the consistent mathematic model,multi-scale surface geometries can be represented precisely.Moreover,the visualization result of the functional surfaces shows that the visualization optimization strategies developed are efficient.

Cast-rolling force model in solid-liquid cast-rolling bonding(SLCRB) process for fabricating bimetal clad strips

Based on twin-roll casting, a cast-rolling force model was proposed to predict the rolling force in the bimetal solid-liquid cast-rolling bonding(SLCRB) process. The solid-liquid bonding zone was assumed to be below the kiss point(KP). The deformation resistance of the liquid zone was ignored. Then, the calculation model was derived. A 2D thermal-flow coupled simulation was established to provide a basis for the parameters in the model, and then the rolling forces of the Cu/Al clad strip at different rolling speeds were calculated. Meanwhile, through measurement experiments, the accuracy of the model was verified. The influence of the rolling speed, the substrate strip thickness, and the material on the rolling force was obtained. The results indicate that the rolling force decreases with the increase of the rolling speed and increases with the increase of the thickness and thermal conductivity of the substrate strip. The rolling force is closely related to the KP height. Therefore, the formulation of reasonable process parameters to control the KP height is of great significance to the stability of cast-rolling forming.

An evolutionary particle filter based EM algorithm and its application

In this paper, an evolutionary recursive Bayesian estimation algorithm is presented, which incorporates the latest observation with a new proposal distribution, and the posterior state density is represented by a Gaussian mixture model that is recovered from the weighted particle set of the measurement update step by means of a weighted expectation-maximization algorithm. This step replaces the resampling stage needed by most particle filters and relieves the effect caused by sample impoverishment. A nonlinear tracking problem shows that this new approach outperforms other related particle filters.

Simulation of Solid Suspension in a Stirred Tank Using CFD-DEM Coupled Approach＊

Computational fluid dynamics-discrete element method(CFD-DEM) coupled approach was employed to simulate the solid suspension behavior in a Rushton stirred tank with consideration of transitional and rotational motions of millions of particles with complex interactions with liquid and the rotating impeller. The simulations were satisfactorily validated with experimental data in literature in terms of measured particle velocities in the tank.Influences of operating conditions and physical properties of particles(i.e., particle diameter and density) on the two-phase flow field in the stirred tank involving particle distribution, particle velocity and vortex were studied.The wide distribution of particle angular velocity ranging from 0 to 105r·min 1is revealed. The Magnus force is comparable to the drag force during the particle movement in the tank. The strong particle rotation will generate extra shear force on the particles so that the particle morphology may be affected, especially in the bio-/polymer-product related processes. It can be concluded that the CFD-DEM coupled approach provides a theoretical way to understand the physics of particle movement in micro- to macro-scales in the solid suspension of a stirred tank.

Simulation and Design Optimization of Ammonia Synthesis Converter

One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.

DETERMINGING BPA UNDER UNCERTAINTY ENVIRONMENTS AND ITS APPLICATION IN DATA FUSION

Dempster-Shafer (DS) theory of evidence has been widely used in many data fusion ap- plication systems. However, how to determine basic probability assignment, which is the main and the first step in evidence theory, is still an open issue. In this paper, a new method to obtain Basic Probability Assignment (BPA) is proposed based on the similarity measure between generalized fuzzy numbers. In the proposed method, species model can be constructed by determination of the min, average and max value to construct a fuzzy number. Then, a new Radius Of Gravity (ROG) method to determine the similarity measure between generalized fuzzy numbers is used to calculate the BPA functions of each instance. Finally, the efficiency of the proposed method is illustrated by the classi- fication of Iris data.

Simulation calculation of solubility of insoluble compound M_mA_a in complex system

A simulation calculation model for the solubility of insoluble compound MmAa in complex system was established.According to coordination equilibrium principle,relevant dissociation reaction,complexation reaction,self-complexation reaction and protonation reaction during insoluble compound dissolving were considered and then the mass balance equations about solubility calculation were obtained.In the case analysis,the solubility of silver chloride in ammonia system was obtained by simulation calculation,and curved surface charts of thermodynamic equilibrium about the total concentration of silver ions,pH and concentration of ammonia ions were drawn correspondingly.The results show that under the conditions of room temperature and 6 mol/L ammonia concentration,the calculated solubility value of silver chloride(34 g/L) is close to the actual value(31 g/L),demonstrating that this model is suitable for solubility calculation of insoluble compound MmAa in the complex system.

Modeling and simulation of Cobot based on double over-running clutches

In order to analyze characteristics of Cobot cooperation with a human in a shared workspace, the model of a non-holonormic constraint joint mechanism and its control model were constructed based on double over-running clutches. The simulation analysis was carried out and it validated passive and constraint features of the joint mechanism. In terms of Cobot components, the control model of Cobot following a desired trajectory was built up. The simulation studies illustrate that the Cobot can track a desired trajectory and possess passive and constraint features ; a human supplies operation force that makes Cobot move, and a computer system con- trois its motion trajectory. So it can meet the requirements of Cobot collaboration with an operator. The Cobot model can be used in applications of material moving, parts assembly and some situations requiring man-machine cooperation and so on.

Flexoelectric-Induced Voltage Shift in Hybrid Aligned Nematic Liquid Crystal Cell

Flexoelectric-induced voltage shift in a weak anchoring hybrid aligned nematic fiquid crystai cell is investigated theoretically. Based on the elastic theory of liquid crystal and the variation method, the equations for the bulk and the boundary of the cell are derived. By computer simulation, the dependence of the shift voltage on the sum of the ttexoelectric coefficients and the anchoring energy strength is obtained. As a result, a novel method to determine the sum of the flexoelectric coefficients by measuring the shift voltage is put forward.

Random Model and Simulation for Nucleation Stage of Emulsion Polymerization

The method of mathematical model and further computer simulation is an effective way to the theoretical study of emulsion polymerization and the scale-up of the reactors. In this work, Monte Carlo method has been used to simulate the nucleation of emulsion polymerization. The effects of emulsifier concentration [S] and initiator concentration [I] on various parameters such as the number of the particles (N p), the average diameter of the latex particles (D p), monomer conversion (x) and average radical number per particle (n) have been studied. The quantitative equations between [S], [I] and N p are in accord absolutely with the classical theory of Smith-Ewart.

Pattern Specialization Based on Partial Evaluation

Design pattern enables software architecture generality and reusability, but which depresses the high performance. The pattern specialization was built on partial evaluation technology to reduce the overheads of design pattern. The design patterns were classified to extract the common features, and the corresponding pattern specializations were constructed. In the pattern specialization, the optimization opportunities were identified, and the specialization methods and conditions were described. The syntax of binding time analysis was defined, and the semantic depicted the invariant of usage context. The virtual invocation and dispatch were eliminated, which enhances the running efficiency. This pattern specialization is a high-level specialization for improving the performance of software aimed at design level that is orthogonal with the low-level code optimization.