非线性方程的Excel拟合及其应用

介绍了如何利用Excel软件中的“规划求解”工具进行非线性方程的最优拟合以及应用注意事项。采用Gause的4组草履虫数据,研究了用Excel的“规划求解”工具进行非线性方程拟合的有效性,并以莫惠栋的《农业试验统计》一书中的12个非线性方程实例,比较了用Excel拟合与用常规线性转换方法拟合的差异,结果表明：用Excel进行非线性方程的拟合不仅简单易行、获得更优的参数估计,而且可以拟合各种复杂的非线性方程。     

Research on Machining Last by Numerical Controlled Last Carving Machine

System structure of last CAD/CAM is described. Then machining principle of system output device named numerical controlled Last Carving machine is introduced. Furthermore, we lay stress on analyzing machining programming method making use of direct numeric definition. Special disposal is taken on step error and working frequency of step motors so that not only error accumulation is avoided but also step motors always work in the best frequency range. As a result, machining precision and speed of last are both enhanced as well as step motors' working safety is guaranteed.     

Using A Shock Fitting Based on Characteristics For 1-D Dam-break Flow

By using the method of characteristics, a shock fitting schemes for computation of gas dynamics is proposed and used to simulate the 1-D unsteady open channel flow of sudden dam break. The calculation results are compared with analytic solutions. It is demonstrated that high accuracy, good stability are obtained and good shock-capturing ability is shown.     

Numerical Simulation of the Separation Effect of a Rotational Flow Sedimentation Tank Based on Fluent

This paper introduced FLUENT CFD simulation software and based on this software, the numerical modeling of the rotational flow sedimentation tank is set up and calculated. The separation efficiency curve and accumulation efficiency curve have been obtained and the deposition character inside the rotational flow sedimentation tank is shown. The conclusions given in this paper are valuable to the further improvement of the rotational flow sedimentation tank design.     

Optimization of Curve Fitting Used in Development of Magic Formula Tire Model

Characteristics of a tire are the foundation of vehicle dynamics studying, especially play a vital role in vehicle handling study. It is necessary to establish a tire model in the simulation for vehicle handling because the tire characteristics got by test can not be satisfied.The optimization of fitting to the tire test data curves by Magic Formula is discussed, included the digitalization of tire test data curves, designing objective functions and optimization processes,etc. Finally the parameters in Magic Formula tire model are obtained and they lay a foundation for the development of vehicle handling aftertime.     

The Research on the Computational Method of Cam Lift in Auto Measuring Instrument for the Cam Shaft

In this paper,the seeking optimum method for determining symmetrical axis of cam, the method for acquiring the obsolute lift value of every sampling-point on cam, and the method for obtaining the lift error of node on cam as well as curve of lift error by fitting with N order harmonic components are described. These methods, mentioned above consist of the computational methods for cam lift error by the computer controlling multi-measuring probes instrument for auto-measuring cam shaft.     

Instantaneous Dynamic Numerical Modeling of Collapsible Loess Foundation Consolidated by Ramming

In this paper, the procedure of single-point and multiple-time ramming for loess is simulated using the finite element method.The graph about the distribution of stress, displacement and pressure in the foundation during dynamic consolidation are provided in a sample with Han-chang expressway as an engineering background.The computational results obtained are compared with the data measured in the consolidation site.An effective path to simulate the consolidation mechanism precisely is provided.     

Numerical Analysis on Bearing Capacity of Piles Subjected to Side Loads

Besides the loading applied by the upper building, the piles are often subjected to indirect loading such as side loads. These kinds of loads would cause the pile bear additional force (negative skin friction), which may be large enough to reduce the bearing capacity and cause structural failure of a pile. By establishing the numerical model of pile soil interaction, the bearing capability of pile under side load was analyzed. The joint effect of different magnitude and the distance of the side load on the skin friction were focused. The joint effect of length of the pile and the distance of side load on the skin friction was discussed. The expression of the two combination relationship was obtained. Meanwhile, by using the least square method, the expression of total skin friction on different side load combination was achieved. And based on the statistical analysis of the dispersion coefficient, the function expression was proved to be of high precision. The results show that when k, which indicates the relative relation of side load distance s and the side load magnitude Q, increases to 32, the value of negative skin friction goes to zero. When c, indicating the relative relation between pile length L and side load distance s, increases to 0.5, the value of negative skin friction goes to zero. Beyond limit value of these two relative relationships, the bearing capability of the pile will not be affected by side loads.     

Research on Mechanical Characteristics of the Cemented Sandstone Based on 3Dimensional PFC Numerical Model

Sandstone is sediment rock composed of many cemented sand particles, and corresponding particle constraint and force bearing capacity are greatly controlled by the cemented property. In order to better reflect the cemented property influencing on the mechanical characteristics of the sandstone, take the oil sandstone reservoir for instance, a numerical model based on 3Dimensional Particle Flow Code (PFC3D) considering the parallel bond model was brought forward to simulate the failure mechanism during shearing process. The sandstone cemented property is modeled based on random mathematics and advanced development of Particle Flow Code (PFC), and the relation of the stress ratio, volume strain, coordination number and bond-broken number and the axial strain is analyzed in detail, especially the contact network evolution indicated the force chain is important to transfer the external force, which verifies the feasibility of the numerical model. Based on the above PFC3D model, a series of researches on changing the cemented radius ratio, parallel bond stiffness and cemented volume of the particles have been done to clearly illuminate the importance of cemented property for the bearing capacity of the sandstone structure, which provides a scientific base for research on the failure mechanism of the sandstone under special conditions. Therefore, the above numerical method is more efficient and applicable for comparatively large scale and complex experiments, and the obtained research results can bring a new thought for the real cemented sandstone to research on its macro-micromechanical response and the structure failure mechanism, and also is significant for the sand production mechanism, sand volume prediction and sand control measures for the sandstone reservoir.     

生物活性多肽分离与检测的研究进展

自从1979年Brantl等人首先从酪蛋白的水解产物中分离到β-酪啡肽-7,对于生物活性肽的制备、分离、纯化等各个方面均有广泛的研究。随着各种生物活性短肽的不断发现,其研究和开发日益受到各国学者的关注。     

Numerical Simulation of Frost Characteristic on Refrigeration System Evaporator

In order to analyze the running performance of refrigeration air conditioning system and confirm thaw periods in reason, frost process and change process of frost thickness of evaporator surface are studied. Based on basic theory and experiential formula of heat transfer process and mass transfer process, the math model of mass transfer of vapor on evaporator outside and growth process of frost are established. Aiming at a sort of finned-tube evaporator, frost process and change process of frost thickness are simulated numerically. The influence of environment parameters is analyzed.     

Case- carburization Numerical Modeling and Craft Optimization on Steel Parts of Various Shapes

According to the diffusion equation of carburizing process and its boundary conditionand initial condition, various shapes steel parts are modeled under various case carburize craft parameters, concentration distribution curves have been obtained. Various craft parameters are compared, and carburizing temperature has more influence on carbon concentration distribution. Various shapes steel parts' carbon concentration distribution curves have some difference. According to the carbon concentration distribution curve, craft parameters can be adjusted in order to obtain the best carburizing craft.     

Numerical Simulation of Groundwater Flow and Quality

With societal development, wastes exist in industry, agriculture and human life. In particular, a large volume of urban industrial sewage is discharged and pesticides and fertilizers are widely used, leading to groundwater pollution in many areas. Based on a water quality model of hydrodynamic dispersion and the multi element balance (MEB) method, a general program for simulating groundwater flow and quality is carried out using the program VC++ for visual presentation. Using this program in a case study, the transportation mechanism of groundwater flow and quality is simulated numerically. The result indicates that the program is visual and can be manipulated well. It offers a point of reference for the reasonable exploitation, protection and utilization of the groundwater.     

Testing sky luminance distribution by fish-eye lens digital cameras

Abstract:To solve the existence of poor synchronization and large error in the sky luminance test, using fish-eye lens digital camera test sky luminance. Through researching on fish-eye lens and the optical characteristics of digital cameras, get the method that extract the luminance and location information of the measured sky element from digital photos, and determine the exposure parameters and the record range of linear brightness. Analyzing and amending the stability of the camera and light transmission rate of fish-eye lens, get a more accurate test values of sky luminance distribution. This provide important techniques means for daylighting research and daylighting observation.     

Numerical Simulation on Drying Characteristics of a Combined Microwave-convection Process

Combined microwave-convection drying characteristics are investigated by numerical simulation. Combined microwave-convection drying has advantage of swift drying and sterilization. Based on qualitative analyses on the mechanism of combined microwave-convection drying, the differential equations are established and the numerical simulation method is described. The humidity, vapor pressure and temperature, along the radius in a spherical pill, are calculated by the numerical simulation during drying process. The calculation results show the relationship between humidity, vapor pressure, temperature and drying time, and that drying process is greatly influenced by input microwave power. The calculation results are good consistent with the experimental datum.