Finite Element Analyses of Spherical Node of Coal Pipeline System of Blast Furnace

The mechanical model of spherical node of coal pipelines of blast furnace is built. Its boundary conditions and loads are presented. Its finite element analyses are used for this structure. Its stress distributing rules are obtained and the security of this structure is evaluated.     

Analytic Solution of Anchor Bolts with Dynamic Detection

Sonoprobe method has been applied in non-destructive inspection of anchorage project. Its fundament is that to use dynamic transient excitation for inducing anchor bar's elastic vibration. The flaws in the bar can be estimated or deduced by determining transient response of anchor bar. Based on the theory of elasto-dynamics, in this paper, a theoretical model of acoustic detection of anchor bar has been built up. On the mechanics field, this method means that if information of disturbance resource, boundary conditions and initial conditions has been given, the dominant equation describing medium motion would be established. That is, it leads to the problem of initial value or initial boundary value of hyperbolic type or hyperbolic-diffusibility type equation. Thereby the dynamic response could be solved. As an example, analytic solution of heterogeneous wave equation is deduced in case of bounded region.     

Theoretical Analysis for the Performance of HVDC Grounds Electrodes and the Mathematical Modal

The performance of HVDC ground electrodes is analyzed in detail.On the basis of electromagnetic field theories and its assumptions,the mathematical model is built,the ground resistance,the distribution of potential and temperature are computed with the current field distributions of HVDC ground electrodes.     

氧气高炉多流体数值模拟与分析

为研究不同氧气高炉操作流程及操作参数对高炉内部过程产生的影响,预测氧气高炉流程各参数的变化规律,基于多流体理论、冶金传输原理、冶金反应动力学与热力学理论以及计算流体力学建立了普通高炉多流体模型,并在此基础上修改边界条件及内部相关参数,建立氧气高炉多流体数学模型。通过建立的模型分别对普通高炉和气化炉氧气高炉(GF-FOBF)流程中的氧气高炉进行了模拟计算,得到两种工艺流程下高炉内温度场、浓度场和速度场等典型参数的分布情况。通过对计算结果的对比,分析了氧气高炉操作条件下炉内状态的主要特征和相对于普通高炉发生的变化,发现氧气高炉内部速度场、温度场均发生变化,特别是气相组分的均匀分布问题明显。本模型可为氧气高炉流程试验及流程开发提供参考。     

主动式冷梁热工性能仿真模型及实验验证

以无限空间射流理论和表冷器换热理论为基础,对主动式冷梁的工作原理进行了分析。在假设条件下,建立了诱导送风模型和干工况表冷器换热模型。结合这两种模型,最终建立了主动式冷梁工作模型。在设定的5种静压箱静压值下,对主动式冷梁样品的一次风量、二次风量、水侧换热量等热工参数进行测试。选取诱导比和制冷量两个表征冷梁性能的参数作为标准,对模型理论值与样品实际值进行了一致性与差异性分析,验证了所构建的主动式冷梁模型。     

风电齿轮箱传动误差分析及振动噪声预估

针对一级行星两级平行轴风电齿轮传动系统,综合考虑齿轮时变啮合刚度、啮合阻尼、传递误差等因素,建立31个自由度的弯扭轴耦合集中参数动力学模型,采用变步长Runge-Kutta法对系统动力学微分方程进行求解,得出齿轮传动系统各级传动误差;借助软件建立风电齿轮箱刚柔耦合动力学模型,并导入传动误差,采用模态叠加法求得齿轮箱轴承支反力,并将其作为声振耦合模型的边界条件,采用声学有限元法对风电齿轮箱进行振动噪声预估,并与试验结果对比分析,两者吻合良好。     

A mathematical description of the liquid flows inside blast furnaces

The knowledge of liquid flows in blast furnaces may play an important role in controlling the blast furnace process. Appropriate assumptions are given to represent the main characteristics of the liquid flow in blast furnaces, such as liquid streams being composed of unwetting liquid droplets, inertial force having little effect on the liquid flows, and mass exchange existing along the direction perpendicular to liquid flow. A mathematical model is built to predict the distribution of the liquid flow rate and the liquid flow range in packed beds. The scale of the numerical grid used to solve this model may not necessarily be reduced to the particle level. The predicted results of this model accord well with the observed data. This model is an alternative theory for the simulation of blast furnaces     

THE THREE-DIMENSIONAL CALCULATING MODEL OF INVERSE PROBLEM IN ECG AND A SPECIAL BOUNDRYVALUE PROBTEM

In this paper, the mathematical model and the three-dimensional finite clement formulation of inverse problem in electrocardiography (ECG) under a general inhomogcneous and anisotropic configuration of the torso conductor is focused on. The following points are especially considered: 1. The mathamatical model is described by a differential equation instead of the Fredholm integral equation. 2. A kind of special boundary value problem is defined as ill-posed boundary value problem. 3. A group of finite element formulation, in which the method that treats anisotropic medium, is built up. 4. The calculating method of ill-posed boundary value problem is discussed.     

Junction stiffness analysis and vibration noise prediction of wind power speed-increase gearbox

In order to study the vibration characteristics and radiation noise of wind power speed-increase gearbox, a torsional vibration model of wind power speed-increase gearbox is established based on the analysis of supporting stiffness of bearing and contact stiffness of gear pairs. By solving the vibration differential equation with the help of Matlab, the frequency and corresponding vibration mode are obtained. With taking stiffness excitation, error exaction and meshing impact exaction into account, the dynamic finite element model of speed-increase gearbox is set up, and the dynamic response simulation is carried out. Regarding vibration displacement of the nodes on gearbox surface as boundary condition, an acoustic boundary element model of speed-increase gearbox is built. The surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The results show that there is a great difference between torsion frequency and excitation frequency of wind power speed-increase gearbox, and so the resonance doesn't occur. The maximum structural noise and radiation noise mainly appear near the double octave of the gears meshing frequency of high-speed grade.     

Numerical simulation of dynamic response and radiation noise of gearbox

Considering the internal dynamic excitation produced by stiffness excitation, error excitation and mesh impact excitation, a dynamic finite element model of transmission system and structure system of gearbox is established. The normal mode and the dynamic responses of gearbox under the internal dynamic excitation are calculated by using the numerical simulation software ANSYS. Based on the result of dynamic responses, the boundary excitation condition is determined, and then the acoustic boundary element model is built. With the software of SYSNOISE, the surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The test of airborne noise is carried out. The computational results obtained are in a good agreement with the data of experimental test.     

The improved geometrical constraint model of open-pit mine boundary optimum and its application

This paper develops the improved geometric constraint model (IGCM) based on the 3D block model. The variable-slope excavation cones of each block have been abstracted to collections of nodes and directed edges, and the optimization method has been introduced using the set theory. The IGCM consists of the optimized collection nodes and directed edges. The algorithm based on IGCM has been actualized in DIMINE digital mine system, and is applied to an actual open pit mine boundary optimization engineering. The results shows that IGCM can accurately simulate variable slope angles in any azimuth and elevation changes, and adapt to all open pit mine boundary optimum problems in any complex geological conditions, calculation speed and accurate. It provides a new and effective method for the variable-slope open pit mine boundary optimization problem in complex geological conditions.     

Analytical and Experimental Study on Performances of MR Fluid Dampers Employing Plates Channel Model

The numerical model,which combines the two-dimensional river model and ship maneuvering mathematical model,is built.The influence of Nanjing Fourth Bridge to be built across the Changjiang River on river's condition is studied.The change of river conditions around the Bridge pier is analyzed and the tracks of ship transit along the reach of the Changjiang River are simulated for the cases of before and after building the Nanjing Fourth Bridge.The parameters of navigation in sail course have been obtained.The result shows that the influence on rivers condition of the Nanjing Fourth Bridge on Changjiang River is very small,and its influence on navigation is not significant.     

MecaNiCAL, a supply–demand model of carbon and nitrogen partitioning applied to defoliated grass: 2. Parameter estimation and model evaluation

The MecaNiCAL model of carbon and nitrogen partitioning over a period of regrowth for a mean grass plant as described in Part 1 was fitted and evaluated against data from an experiment under controlled conditions with contrasting light and nitrogen nutrition. In the first investigation, the rate of nitrogen uptake was imposed to limit the compensation of errors between process. The root:shoot ratio was simulated well, with a good estimation of the nitrogen allocation to shoots. Some underestimation of the root weight after the cut and the final shoot weight under the low nitrogen treatment were consequences of both the lack of remobilisation and the high priority given to shoots. The good agreement obtained with the expected trend in simulations conducted with the simple nitrogen aborption submodel in extended conditions (contrasting initial content of nitrogen substrate and temperature change in regrowth) ensures the general consistency of the model in the limit of its area of validity. Partitioning to shoots and forage production seem to be sensitive mainly to the size of the carbohydrate substrate pool and its availibility, particularly under conditions of low light. Estimating the initial carbohydrate substrate pool by biochemical analysis may improve the accuracy of the model. Compared with more simple assumptions of partitioning, MecaNiCAL shows a higher level of agreement with the partitioning response to a wide range of environmental conditions. A simple assumption relating partitioning to plant nitrogen content does not seem to be sufficient to simulate the decrease in the root:shoot ratio observed under conditions of low light. Nevertheless, more data from experiments conducted under a wider range of contrasting conditions are required to estimate the validity of MecaNiCAL attached to the nitrogen absorption submodel and the advantage of its more complex assumptions with even greater accuracy.     

The Mathematic Model of H eat Transfer for the Solidification of Bille t D u ring Continuous Casting Process

In this paper according to different cooling feafures in the secondary coolingzone,a two-dimensional mathematic model of heat transfer is developed,which is suitable for the op-eration of the casfer in Chongqin g Special Steel Plant,In the model, a finite difference method isadopted and different boundary conditions a different time-step is firstly used.Thus the model isof high precision with a shorter calculation time.The optimum secondary cooling system of the con-tinuous billet can be gained by aimulating and optimizing calculations using the model.     

Hybrid field network simulation of temperature in a building fire

A connecting platform between the field model and network model has been constructed, based on a multi functional building model. The field model is used to simulate the fire smoke in certain special compartments (the fire room and specific large space rooms), while the network model is used to simulate the uniform compartments. When combining the simulation results of the field model and network model as the interface boundary conditions for the each other, a hybrid field and network model is presented. The hybrid field network model can provide more detailed physical information of the fire smoke properties under a specific fire scenario for the specially confined compartments. In addition, the hybrid model can predict the fire smoke flow properties in the building accurately.     

考虑预估驾驶行为的跟驰模型及其稳定性分析

在OV模型的基础上,进一步考虑预估驾驶行为对车流的影响,提出一个新的跟驰模型以获得预估驾驶行为与交通拥堵的关系。通过对新模型进行稳定性分析得到了系统的临界稳定条件。数值仿真结果表明：新模型能够模拟诸如时停时走、系统临界相变等实际交通现象,较OV模型更贴近于实际。同时,预估驾驶行为增强了交通流稳定性能,提高了车流陷入交通阻塞状态的阈值。最后以车速的平滑度和波动幅度最小为评价指标得到了新模型中预估参数的最优取值范围。     

Analysis on the Diffusion Hazards of Unsteady Leakage of Gas Pipeline

Through analysis on the process of unsteady leakage of gas pipeline,the calculating model of unsteady leakage rate has been established.According to the variable characteristic of unsteady leakage ratio,based on the differential equation of on-flow diffusion,and combining the relevant original and boundary conditions,the diffusion model of unsteady leakage of gas pipeline has been established.Based on the practical application,all of the dangerous areas have been discussed and analyzed.The damaging and destroying areas have been calculated under definite conditions.This will provide safety standards and references for confirming and formulating the safety distance for the important buildings(school etc.) apart from the long high-pressure gas pipeline and main gas pipeline in city.At the same time,this will provide guarantee for reducing the dangerous degree,when accidents happened.     

Dynamic Simulation on the Hoisting Mechanism of a Crane

Considering the difficulties of mathematical analysis and the complex computer programming of numerical methods in solving dynamical problems of the multi-body dynamic system for the hoisting mechanism of a crane, in this paper, a multi-mass-multi-freedom model is set up and the simulation system of the model is built up applying MATLAB/SIMULINK toolbox. The differential equations of the model is solved with adaptive-step fourth-order Runge-Kutta method. In the study, the typical work conditions of the hoisting mechanism, such as start rise from ground, start rise/down in air, brake conditions, were simulated. The dynamic performance of the hoisting mechanism is studied and the results obtained are valuable to practice. This study improves the modeling accuracy of the hoisting mechanism and the results of precious theoretical analysis and numerical computation conclusions. The movement of every discrete body of the system can be modeled applying the methods suggested by this study and more consistent results between model and actual hoisting mechanism can be achieved.     

Defects detection in the inner surface of pipes based on inverse heat conduction problem

It is a typical ill posed inverse heat conduction problem to estimate the geometry boundary of the inner surface of pipe by the temperature of outer surface. With the establishment of a two dimensional steady model for pipe with irregular inner surface, the inverse problem is transformed into a direct problem and an optimization problem. Based on the temperature at the outer surface obtained from the infrared thermography and the variation of the object function, the conjugate gradient method (CGM) is introduced into the geometry problem. With the numerical analysis of three typical defects, the effects of the measurement errors, choice of the initial value, boundary conditions and number of discrete temperature points are discussed and the proposed methodology is approved.     

粘贴加固混凝土氯离子扩散的理论模型和数值模拟

基于物质非稳态扩散理论,采用现有研究对Fick第二定律的修正方法,并将粘贴加固考虑为对氯离子扩散方程边界条件的调整,提出可用于粘贴加固混凝土的氯离子扩散理论模型。利用ABAQUS、MATLAB PDE tool、MATLAB自编程3种方法均可对粘贴加固混凝土梁的氯离子扩散过程进行数值模拟。对比未加固与加固构件的氯离子扩散规律,发现粘贴加固可降低钢筋表面的氯离子浓度值,延缓氯离子浓度到达临界锈蚀浓度的时间,增加材料使用寿命,并且加固时间越早,增加寿命越长。