Fe-∑Xi-C合金系超组元模型Zener两参数的修正

根据Aaronson提出的超组元模型,借助A_(e3)的实验数据,提出了修正的置换型元素X_i(X_i=Si,Mn,Ni,Co,Mo, Al,Cu,Cr)的Zener两参数,修正中考虑了合金元素间的交互作用.修正后的超组元模型的预测精度明显改善:A_(e3)计算值与实验值的标准差为10.8℃,与Thermo-Calc计算值的标准差为2.35℃;A_(e1)计算值与实验值的标准差为6.8℃.按照马氏体相变热力学的计算方法,采用经修正的参数计算了马氏体相变开始温度M_s,提高了M_s点的预测精度,计算值与实验值的标准差为25.3℃.

多组分流元模型在稀性泥石流堆积分选特征研究中的应用

基于结构两相流模型和PIC数值计算方法 ,本文探讨了稀性泥石流堆积过程中的泥沙分选特征 .文中的模型可以模拟阵性泥沙流的非稳定特性 ,通过将传统的Euler和Lagrangian方法结合泥沙流运动的整个过程都能够采用多组分流元模型进行很好的描述 .该模型也能够合理描述泥沙分选过程中伴随的冲淤过程 .文中采用 2～ 5°的坡度 ,固相颗粒被分为三组粒径不同的组分 .研究表明 ,泥石流的垂向和横向分选都不明显 ,但是纵向分选较为明显 .河槽坡度和泥石流的密度是影响泥石流分选过程的两个关键因素 .泥沙输移能力越大 ,颗粒分选越不明显 。

三种局部平衡模式下Fe-∑X_i-C合金系相变的超组元模型

将正平衡(Ortho-equilibrium,OE)、准平衡(Para-equilibrium,PE)和忽略分离的局部平衡模型(Negligible/No partition localequilibrium,NPLE)引入超组元模型的计算中,计算了Fe-0.1C-1.5Mn-0.5Si和Fe-0.21C-0.51Mn-0.2Si钢在γ→α+γ'、γ→α+cem转变过程中的相界面浓度、相变驱动力和相变平衡开始温度。3种局部平衡模式下计算得到的Ae3、Ae1与Thermo-Calc计算值和文献实测值吻合较好,误差在4%以内。

X100管线钢的修正超组元模型计算

考虑了合金元素间的交互作用,对超组元热力学模型进行修正,并利用该修正后的模型计算得到X100管线钢中合金元素和形变储能对铁素体相变参数的影响规律。结果表明：模型计算的奥氏体转变为铁素体的温度A3高于Thermo-calc软件计算结果;形变储能增加提高了铁素体相变驱动力与形核驱动力,但随温度变化不显著;随着合金元素含量的增加,Mo比Ni、Cr更能显著降低铁素体和珠光体相变驱动力。

张力减径过程组元建模技术及有限元模拟

根据张力减径过程的变形特点 ,提出了全过程仿真的组元建模技术 ,建立了张力减径过程的组元模型 ,并利用三维弹塑性大变形有限元程序模拟了典型的钢管轧制过程 ,结果与试验数据吻合。

管材张力减径有限元快速仿真系统的研究

根据张力减径过程的变形特点,采用组元建模技术,编写了弹塑性有限元计算程序。利用AutoCAD进行图形后处理,并通过VB建立人机交互界面,开发了管材张力减径过程快速仿真系统。研究了管材张力减径的变形过程,预报了轧后产品几何形状、应力、应变等分布状态。模拟结果与生产实测结果吻合良好,表明该系统能够胜任钢管张力减径过程模拟及产品质量预报工作。

Measurement and Prediction of Vapor Pressure for H20 ＋ CHaOH] C2HsOH ＋ [BMIM][DBP] Ternary Working Fluids

The ionic liquid, 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) was prepared and the vapor pressures of three set of binary solutions H2O(1)/CH3OH(1)/C2H5OH(1) + [BMIM][DBP](2) were measured at different temperature and in the ILs mole fraction range from 0.1 to 0.6 with a static equilibrium apparatus. The measured vapor pressures were correlated with Non-Random Two Liquid (NRTL) activity coefficient model and the average relative deviations (ARD) between experimental and correlated vapor pressures for these binary solutions were 3.19%, 2.42% and 2.95%, respectively. Then, the vapor pressures of two set of ternary solutions H2O(1) + CH3OH(2)/C2H5OH(2) + [BMIM][DBP](3) were measured with an inclined boiling apparatus and further predicted with NRTL activity coefficient model based on the binary interaction parameters coming from fitting the vapor pressures of the binary solutions. The results indicated that the ternary solutions containing [BMIM][DBP] were shown a strong negative deviation from Raoult's Law when the mole fraction of [BMIM][DBP] was larger than 0.2, which meant that ternary solutions could absorb the refrigerant vapors at the same or below solution temperature. Meanwhile, the average relative deviations between experimental and predicted vapor pressures for ternary solutions were 2.92% and 3.06%, respectively. Consequently, the NRTL active coefficient model used for non-electrolyte solutions was still valid for predicting vapor-liquid equilibrium of binary or ternary solutions containing ILs.

Dynamic probabilistic analysis of stress and deformation for bladed disk assemblies of aeroengine

In order to describe and control the stress distribution and total deformation of bladed disk assemblies used in the aeroengine, a highly efficient and precise method of probabilistic analysis which is called extremum response surface method(ERSM) is produced based on the previous deterministic analysis results with the finite element model(FEM). In this work, many key nonlinear factors, such as the dynamic feature of the temperature load, the centrifugal force and the boundary conditions, are taken into consideration for the model. The changing patterns with time of bladed disk assemblies about stress distribution and total deformation are obtained during the deterministic analysis, and at the same time, the largest deformation and stress nodes of bladed disk assemblies are found and taken as input target of probabilistic analysis in a scientific and reasonable way. Not only their reliability, historical sample, extreme response surface(ERS) and the cumulative probability distribution function but also their sensitivity and effect probability are obtained. Main factors affecting stress distribution and total deformation of bladed disk assemblies are investigated through the sensitivity analysis of the model. Finally, compared with the response surface method(RSM) and the Monte Carlo simulation(MCS), the results show that this new approach is effective.

Influence of Selective Edge Removal and Refractory Period in a Self-Organized Critical Neuron Model

A simple model for a set of integrate-and-fire neurons based on the weighted network is introduced. By considering the neurobiological phenomenon in brain development and the difference of the synaptic strength, we construct weighted networks develop with link additions and followed by selective edge removal. The network exhibits the small-world and scale-free properties with high network efficiency. The model displays an avalanche activity on a power-law distribution. We investigate the effect of selective edge removal and the neuron refractory period on the self-organized criticality of the system.

Complex Behavior in a Selective Aging Neuron Model Based on Small World Networks

Complex behavior in a selective aging simple neuron model based on small world networks is investigated. The basic elements of the model are endowed with the main features of a neuron function. The structure of the selective aging neuron model is discussed. We also give some properties of the new network and find that the neuron model displays a power-law behavior. If the brain network is small world-like network, the mean avalanche size is almost the same unless the aging parameter is big enough.

Meta-model Based Model Organization and Transformation of Design Pattern Units in MDA

To achieve the purpose of applying design patterns which are various in ldnd and constant in changing in MDA from idea and application, one way is used to solve the problem of pattern disappearance which occurs at the process of pattern instantiation, to guarantee the independence of patterns, and at the same time, to apply this process to multiple design pattems. To solve these two problons, the modeling method of design pattern traits based on meta-models is adopted, i.e., to divide the basic operations into atoms in the metamodel tier and then combine the atoms to complete design pattem units meta-models withtout business logic. After one process of conversion, the purpose of making up various pattem traits meta-model and dividing business logic and pattern logic is achieved.

Verified Solution for a Statically Determinate Truss Structure with Uncertain Node Locations

We consider a statically determinate structural truss problem where all of the physical model parameters are uncertain： not just the material values and applied loads, but also the positions of the nodes are assumed to be inexact but bounded and are represented by intervals. Such uncertainty may typically arise from imprecision during the process of manufacturing or construction, or round-off errors. In this case the application of the finite element method results in a system of linear equations with numerous interval parameters which cannot be solved conventionally. Applying a suitable variable substitution, an iteration method for the solution of a parametric system of linear equations is firstly employed to obtain initial bounds on the node displacements. Thereafter, an interval tightening （pruning） technique is applied, firstly on the element forces and secondly on the node displacements, in order to obtain tight guaranteed enclosures for the interval solutions for the forces and displacements.

Determinants of Household Food Security in Nepal:A Binary Logistic Regression Analysis

The study reveals that 10.2% of the sampled households in Nepal suffer from chronic food insecurity,i.e.,neither are they able to produce sufficient food from their farms nor earn the food security threshold income for deficit months.With the highest and the lowest exponential value of coefficient obtained from binary logistic regression model,it is concluded that any program targeting occupational caste and small landholding farm category or landless will contribute significantly to reduce food-insecurity.The provision of employment opportunities for economically active age group,thus,reducing dependency ratio from 1.2 (economically active population) to 0.7 (economically active age group) can also contribute significantly to reduce food insecurity.Significant positive coefficient of family size squared shows the increase in the probability of being foodinsecure with the increase in family size.In addition,an increase in irrigation availability can contribute significantly to reduce food insecurity.A significant proportion of male-headed households and households residing in Tarai are food-secure.This justifies the need to target female-headed households and households residing in Mountain and Hill in any program aimed at resolving food insecurity.A negative and significant association of household's participation in community organizations and food insecurity fortifies the need for inclusion of vulnerable groups such as occupational caste,female-headed households,households with illiterate heads,small landholding farm category or landless,and households residing in Mountain and Hill (including some target communities in Tarai) in community organizations.Furthermore,making these communities a target of food security programs can help significantly to reduce the incidence of food insecurity.

A novel progress of leg tissue properties modeling based on biomechanics

To describe strategies for addressing technical aspects of computational modeling of leg tissue with the finite element （FE） method, a patient＇s leg sample was selected and scanned by CT at the direction parallel to the Frankfort Horizontal plane. A three-dimensional （3D） finite element model of the human leg was developed using the actual geometry of the leg skeleton and soft tissues, which were obtained from 3D reconstruction of CT images. All joints were defined as contact surfaces, which allow relative articulating movement. The major ligaments were simulated using tension-only truss elements by connecting the corresponding attachment points on the bone surfaces. The bony and ligamentous structures were embedded in a volume of soft tissues. The muscles were defined as non-linear viscoelastic material, and the skin, ligaments and tendons were defined as hyperelastic, while the bony structures were assumed to be linearly elastic. The muhilayer FEM model containing thighbone, tibia, fibula, kneecap, soft tissue was formed after meshing. Diverse forces were imposed on the FEM model. The results show that the multilayer FEM model can represent tissue deformation more accurately.

Evaluation of Adhesive Joints for Combined Load Test-Fixtures

Abstract： In a test-fixture that the authors were using, steel tabs adhesively bonded to an aluminum panel debonded before the design load on the real test panel was fully applied. Therefore, studying behavior of adhesive joints for joining dissimilar materials was deemed to be necessary. To determine the failure load responsible for debonding of adhesive joints of two dissimilar materials, stress distributions in adhesive joints as obtained by a nonlinear finite element model of the test-fixture were studied under a gradually increasing compression-shear load. It was observed that in-plane stresses were responsible for the debonding of the steel tabs. To achieve a better understanding of adhesive joints of dissimilar materials, finite element models of adhesive lap joints and ADCB （asymmetric double cantilever beam） were studied, under loadings similar to the loading faced by the test-fixture. The analysis was performed using ABAQUS, a commercially available software, and the cohesive zone modeling was used to study the debonding growth.

Optimizing selection of bridge raft based on fuzzy matter-element model and combination weighting

It＇ s a necessary selection to support the maneuver across Yangtze River by floating bridge constructed by portable steel bridge and civilian ships. It is a comprehensive index for the scheme of bridge raft, containing a variety of technical factors and uncertainties. The optimization is the selection in the constructing time, quantity of equipments and man power. Based on the calculation result of bridge rafts, an evaluating system is established, consisting of index of spacing between interior bays, raft length, truss numbers, operation difficulty and maximal bending stress. A fuzzy matter element model of optimizing selection of bridge rafts was built up by combining quantitative analysis with qualitative analysis. The method of combination weighting was used to calculate the value of weights index to reduce the subjective randomness. The sequence of schemes and the optimization resuh were gained finally based on euclid approach degree. The application result shows that it is simple and practical.

Simulation of solidification microstructure of Fe-6.5%Si alloy using cellular automaton-finite element method

3D microstructures of Fe–6.5%Si(mass fraction) alloys prepared under different cooling conditions were simulated via finite element-cellular automaton(CAFE) method. The simulated results were compared to experimental results and found to be in accordance. Variations in the temperature field and solid-liquid region, which plays important roles in determining solidification structures, were also examined under various cooling conditions. The proposed model was utilized to determine the effects of Gaussian distribution parameters to find that the lower the mean undercooling, the higher the equiaxed crystal zone ratio; also, the larger the maximum nucleation density, the smaller the grain size. The influence of superheat on solidification structure and columnar to equiaxed transition(CET) in the cast ingot was also investigated to find that decrease in superheat from 52 K to 20 K causes the equiaxed crystal zone ratio to increase from 58.13% to 65.6%, the mean gain radius to decrease from 2.102 mm to 1.871 mm, and the CET to occur ahead of schedule. To this effect, low superheat casting is beneficial to obtain finer equiaxed gains and higher equiaxed dendrite zone ratio in Fe–6.5%Si alloy cast ingots.

Optimal design of modular dual-field modulated permanent magnet linear motors with thrust characteristics

To reduce thrust ripple and cost and improve the average thrust of permanent magnet linear motors,a modular dual-field modulation permanent magnet linear motor was studied,and the parameters were optimized.First,sensitive parameters were selected using the Taguchi method,and then the optimal variables were sampled using the optimal Latin hypercube experimental design method and an ensemble of surrogates model of optimization objectives,and its accuracy was verified.Next,a multi-objective particle swarm optimization algorithm was used to optimize the purpose of“maximum average thrust and minimum thrust ripple”,and the Pareto front of average thrust and thrust ripple was obtained.Finite element analysis showed that the optimized modular dual flux-modulation permanent magnet linear motor(MDFMPMLM)had a 29.5%reduction in thrust ripple and a 5%increase in average thrust compared to the original motor.This study provided an effective method for improving the performance of permanent magnet linear motors.

TRIP钢相变平衡温度A_(e3)和A_(e1)的计算

采用超组元模型和LFG模型,计算了TRIP钢的碳在γ/α相界面处奥氏体侧的平衡浓度xγC/α、先共析铁素体相变驱动力ΔGγ→α+γ1和珠光体相变驱动力ΔGγ→α+cem以及相变平衡温度Ae3和Ae1,并分析了不同热变形和化学成分的影响。计算TRIP钢未变形条件下的相变平衡温度Ae3和Ae1与试验值吻合较好,显示了本文相变热力学计算的较高精度。