基于物理的GaAs MESFET模型参数计算

根据材料性能和物理结构参数近似计算 Ga As MESF ET等效电路模型参数 ,并给出等效电路参数随物理参数的变化曲线。

计算模型对简支箱梁和T梁剪力滞结果影响

以剪力滞效应为研究对象,分别采用MIDAS和ANSYS两种软件配合不同的荷载形式、单元类型和网格密度对一个简支箱梁模型和一个实际简支T梁结构进行计算对比,分析了模型参数和荷载类型对所得结果的影响,为剪力滞效应的有限元分析提供了参数。研究表明:对于同一计算工况,ANSYS比MIDAS所得应力幅值略大,实体单元比板单元所得应力幅值略大,高密度网格比低密度网格所得应力幅值略大,但偏差大都在±5%以内;当腹板与顶板无承托时,对于任意荷载作用,两种软件的1倍网格板单元即可准确得到顶板的剪力滞效应;当腹板与顶板有承托时,在点荷载和线荷载作用下,可采用板单元进行顶板的剪力滞效应分析,但对面和体荷载,则需要采用实体单元进行分析,并且均可采用1倍网格密度。

气流携砂参数计算模型分析

确定井筒中气流携砂的合理工艺参数,力求高速含砂气流对井口设备的冲蚀、磨蚀程度最小,又能保证有足够带出全部砂粒的气流,对气井正常生产至关重要。以砂粒受力是其运动的本质为出发点,通过分析井筒中砂粒的受力情况,建立气流携砂的参数计算模型。在临界状态下,砂粒受力平衡,据此推导出气流携砂临界参数的理论公式。模型推导的理论公式对气井携砂生产具有一定的借鉴意义。

基于参数计算的电子安全系统起爆回路优化方法

针对电子安全系统起爆回路优化设计过程中,由于缺乏起爆回路参数的量化计算造成了优化方法缺乏针对性的问题,提出了基于参数估算的电子安全系统起爆回路优化方法,该方法通过建立电路参数计算模型,结合起爆电流测试结果,理论计算得到阻性、感性、容性回路参数;优化设计中根据参数类型不同选择不同的优化方法,最终完成起爆回路优化设计。试验验证验证表明,基于参数计算的电子安全系统起爆回路优化方法能够有效降低回路阻性、感性参数对于起爆电流的阻碍影响,提升起爆电流、缩短上升时间,提高起爆能量输出等电路性能,优化设计方法合理可行。

中国坡面水蚀预报模型研究

基于我国坡面水蚀预报模型研究成果,考虑浅沟侵蚀对坡面侵蚀产沙的重要影响,建立了我国坡面水蚀预报模型,给出了模型参数降雨侵蚀力、坡度与坡长、浅沟侵蚀影响因子的算法和采用数值。指出今后应加强土壤可蚀性因子、覆盖—管理因子和水土保持措施因子的研究与集成。利用自然坡面径流小区实测资料对模型进行验证,表明模型具有较高的预报精度,在有浅沟和无浅沟的坡面上,预报精度达88%以上。

坡面水蚀预报模型研究

基于对我国坡面水蚀预报模型研究成果的述评和考虑坡面土壤侵蚀特征,提出了我国坡面水蚀预报模型的基本形式,给出了模型中各参数,如降雨侵蚀力、坡度与坡长、浅沟侵蚀因子的计算公式,并对土壤可蚀性、作物和水保措施等因子的提取方法进行了讨论。

太赫兹时域光谱法测定水中重金属离子

采用太赫兹时域光谱法采集溶液时域数据,经过去噪和时域分析,汞、镉、铜离子溶液分别在频率为1.7 THz、0.7 THz、1.2 THz位置上建立线性模型,得到拟合效果最佳的决定系数,分别为0.969、0.896、0.932。该方法检出限为0.001 mg/L~0.002 mg/L,空白加标样6次测定结果的RSD为2.0%,加标回收率为94.0%~102%。将该方法用于测定某污水处理厂两个进口的实际水样,结果汞离子未检出。

锚索支护理论及参数确定方法探讨

探讨了巷道锚索支护的连续梁(连续板)减跨理论及软弱顶板悬吊理论,并以这两种理论为依据建立了拱形截面冒落体、三角形冒落体、关键层冒落体三种计算模型,研究了锚索支护参数的确定方法。

影响某高层住宅结构含钢量因素分析

某高层住宅项目,由于建设方对含钢量的控制很严格,故选取其中一个具有代表性的楼栋从结构布置、荷载选取、模型计算参数等方面对结构含钢量的影响进行分析与对比,得到含钢量变化的主要规律。

面板堆石坝施工期坝体沉降变形预测模型研究

总结分析了各种统计预测模型的原理和优缺点,基于堆石体沉降变形机理,提出了一种针对坝顶及坝体表面测点的统计预测模型。采用数学优化通用软件1stOpt计算模型的统计参数并与笔者基于matlab、VB等编写的程序计算结果对比,结果表明1stOpt操作简便,拟合效果好,计算速度快,能大大减少建模的工作量。提出了选取多个在工程实际应用中效果较好的预测模型联合对某个工程建模,选择效果较好者作为实际预测模型的建模方法,经实例计算分析表明:提出的模型精度高,拟合效果好,提出的建模方法也是可行的。

基于统计数据的RRAM器件特性参数分析

本文统计了58款不同结构和不同材料的RRAM器件结构和电学特性参数,根据参数之间的联系建立了器件特性参数的计算模型,用统计学的百分位法计算了器件数据的差异性,获得了RRAM器件参数的定量指标.根据计算结果,我们发现RRAM器件的写时间、擦时间、写能量和数据维持时间均未达到预期指标, ECM器件低阻态时有量子力学效应,而VCM器件则没有量子力学效应. RRAM器件还需要进一步发展才能取代Flash技术.就发展趋势而言, ECM和VCM器件与NOR flash的差距最小,最可能取代NOR flash.

地下水数值模拟与可视化建模系统框架研究

针对现有孔隙地下水有限元数值模拟在三维可视化与空间分析等方面存在的不足,以有限元数值计算方法和3D GIS平台为基础,结合GIS空间分析算法和计算机图形学理论,提出了孔隙地下水有限元分析过程的概念模型的构建、含水层介质的空间离散、水文地质参数提取与赋值等关键步骤,给出了孔隙地下水有限元数值模拟过程在3D GIS下的实现方法和技术框架。该技术框架旨在简化有限元分析流程、优化模型计算效率、实现地下水有限元数值模拟过程及计算结果的三维可视化。结果表明:基于3D GIS构建的三维水文地质模型,可充分反映地下水系统在3D空间上的分布特征,形成合理的水文地质概念模型,所提出的自适应格网动态生成机制,能够有效改进有限元数值模拟精度和效率。

Matlab/Simulink代码生成技术在RTDS上的应用

针对实际电力系统运行和控制的复杂性与Matlab仿真非实时性的矛盾,提出跨平台联合仿真。采用基于Matlab/Simulink代码生成技术与RTDS实时仿真系统相结合的方法,以高压直流输电系统模型为研究对象,利用Embedded Coder开发工具对系统的控制模块进行代码生成,并在RTDS中完成代码移植实验。通过对比仿真波形,验证得到结果行为一致。由此表明,该方法能够有效利用Simulink良好的开发环境和RTDS的实时仿真特性,在离线仿真成功的基础上,完成实时仿真测试,使工作便捷高效,同时保证结果精准可信。

规模化猪场 猪群性能测定与种猪选择方案探讨

论述了规模化养猪性能测定的目的、内容与方法,阐述了种猪选留顺序、主选性状、选择强度、世代间隔等选种选配繁育制度,并提出了选种的综合性状参数法计算模型。

Calculation of maximum surface settlement induced by EPB shield tunnelling and introducing most effective parameter

This study aims to predict ground surface settlement due to shallow tunneling and introduce the most affecting parameters on this phenomenon.Based on data collected from Shanghai LRT Line 2 project undertaken by TBM-EPB method,this research has considered the tunnel's geometric,strength,and operational factors as the dependent variables.At first,multiple regression(MR) method was used to propose equations based on various parameters.The results indicated the dependency of surface settlement on many parameters so that the interactions among different parameters make it impossible to use MR method as it leads to equations of poor accuracy.As such,adaptive neuro-fuzzy inference system(ANFIS),was used to evaluate its capabilities in terms of predicting surface settlement.Among generated ANFIS models,the model with all input parameters considered produced the best prediction,so as its associated R^2 in the test phase was obtained to be 0.957.The equations and models in which operational factors were taken into consideration gave better prediction results indicating larger relative effect of such factors.For sensitivity analysis of ANFIS model,cosine amplitude method(CAM) was employed; among other dependent variables,fill factor of grouting(n) and grouting pressure(P) were identified as the most affecting parameters.

A New Calculation of the In-Medium Quark Condensate at Finite Density and Temperature

The in-medium quark condensate is studied with an equivalent-mass approach in which one does not need to make assumptions on the derivatives of model parameters with respect to the quark current mass.It is shown that the condensate is generally a decreasing function of both the density and temperature with the decreasing speed depending on the confinement parameter.Specially,at given density,the condensate decreases on increasing temperature.The decreasing speed is comparatively small at lower temperature,and becomes very fast at higher temperature.

An improved self-adaptive membrane computing optimization algorithm and its applications in residue hydrogenating model parameter estimation

In order to solve the non-linear and high-dimensional optimization problems more effectively, an improved self-adaptive membrane computing(ISMC) optimization algorithm was proposed. The proposed ISMC algorithm applied improved self-adaptive crossover and mutation formulae that can provide appropriate crossover operator and mutation operator based on different functions of the objects and the number of iterations. The performance of ISMC was tested by the benchmark functions. The simulation results for residue hydrogenating kinetics model parameter estimation show that the proposed method is superior to the traditional intelligent algorithms in terms of convergence accuracy and stability in solving the complex parameter optimization problems.

The cross section calculation of 112Sn(α,γ)116Te reaction with different nuclear models at the astrophysical energy range

The theoretical cross section calculations for the astrophysical p process are needed because most of the related reactions are technically very difficult to be measured in the laboratory. Even if the reaction was measured,most of the measured reactions have been carried out at the higher energy range from the astrophysical energies.Therefore, almost all cross sections needed for p process simulation have to be theoretically calculated or extrapolated to the astrophysical energies.^(112)Sn(α,γ)^(116)Te is an important reaction for the p process nucleosynthesis. The theoretical cross section of ^(112)Sn(α,γ)^(116)Te reaction was investigated for different global optical model potentials,level density, and strength function models at the astrophysically interested energies. Astrophysical S factors were calculated and compared with experimental data available in the EXFOR database. The calculation with the optical model potential of the dispersive model by Demetriou et al., and the back-shifted Fermi gas level density model and Brink-Axel Lorentzian strength function model best served to reproduce experimental results at an astrophysically relevant energy region. The reaction rates were calculated with these model parameters at the p process temperature and compared with the current version of the reaction rate library Reaclib and Starlib.

Calculation of Thermodynamic Parameters for Freundlichand Temkin Isotherm Models

Derivation of the Freundlich and Temkin isotherm models from the kinetic adsorption/desorpt ion equations was carried out to calculate their thermodynamic equilibrium constants. The calculation formulae ofthree thermodynamic parameters, the standard molar Gibbs free energy change, the standard molar enthalpy change and the standard molar entropy change, of isothermal adsorption processes for Freundlich andTemkin isotherm models were deduced according to the relationship between the thermodynamic equilibriumconstats and the temperature.

Bending analysis and control of rolled plate during snake hot rolling

In order to study the bending behavior of aluminum alloy 7050 thick plate during snake hot rolling, several coupled thermo-mechanical finite element(FE) models were established. Effects of different initial thicknesses, pass reductions, speed ratios and offset distances on the bending value of the plate were analyzed. ‘Quasi smooth plate' and optimum offset distance were defined and quasi smooth plate could be acquired by adjusting offset distance, and then bending control equation was fitted. The results show that bending value of the plate as well as the extent of the increase grows with the increase of pass reduction and decrease of initial thickness; the bending value firstly increases and then keeps steady with the ascending speed ratio; the bending value can be reduced by enlarging the offset distance. The optimum offset distance varies for different rolling parameters and it is augmented with the increase of pass reduction and speed ratio and the decrease of initial thickness. A proper offset distance for different rolling parameters can be calculated by the bending control equation and this equation can be a guidance to acquire a quasi smooth plate. The FEM results agree well with experimental results.