方差分量模型协方差阵的谱分解

本文对平衡方差分量模型, 给出了其协方差阵的新的谱分解算法. 该方法的特点是计算简单, 易于理解, 无须复杂的数学知识. 且能够明确显示协方差阵的不同特征值的个数, 以及谱分解中不同特征值所对应的投影阵的显式表示. 基于新方法我们进一步研究了平衡方差分量模型的一些相关性质.本文还研究了一般方差分量模型, 我们首先定义了一般方差分量模型协方差阵的简单谱分解,给出了一般方差分量模型可以进行简单谱分解的充要条件, 并研究了协方差阵简单谱分解的一些性质. 对于协方差阵可以进行简单谱分解的方差分量模型, 本文研究了简单谱分解在其统计推断中的应用.     

A class of stationary random fields with a simple correlation structure

A stationary random field is often more complicated than a univariate stationary time series, since dependence for a random field extends in all directions, while there is only the natural distinction of past and future at any instant in a univariate time series. In this paper we start from a simple correlation structure, derive a class of stationary random fields with the simple correlation function and the simple spectral density function by using linear combinations of separable spatial correlation functions, and discuss a problem of embedding a lattice model into a continuous domain model.     

Efficiency,effectiveness and productivity of marketing in services

In this paper we consider complex deterministic problems, where there are two models that can be used to predict the performance for a given design. One of the models can give a precise estimation, but is complex and time consuming. The other model is simple and fast, but can only give a very crude estimation. We have proposed a learning-based ordinal optimization approach to tackle this problem. In this approach, we first run a simple model for all the designs and a complex model for a few designs, and then, through regression analysis, we estimate the noise trend, and this noise trend together with the crude estimates from the simple model will be used to screen the designs. The proposed approach is applied to solve an integrally bladed rotor (IBR) manufacturing problem where the production sequence and the production parameters need to be determined in order to minimize the overall manufacturing cost while satisfying the manufacturing constraints. The results indicate that, by using a very crude and simple model, we are able to identify good designs with a high degree of confidence.     

A large-eddy-based lattice Boltzmann model for turbulent flow simulation

In this paper a novel and simple large-eddy-based lattice Boltzmann model is proposed to simulate two-dimensional turbulence. Unlike existing lattice Boltzmann models for turbulent flow simulation, which were based on primitive-variables Navier–Stokes equations, the target macroscopic equations of the present model are vorticity-streamfunction equations. Thanks to the intrinsic features of vorticity-streamfunction equations, the present model is efficient, stable and simple for two-dimensional turbulence simulation. The advantages of the present model are validated by numerical experiments.     

解大型无约束优化的新的非单调简单模型BB-TR方法（英文）

The trust region(TR) method for optimization is a class of effective methods.The conic model can be regarded as a generalized quadratic model and it possesses the good convergence properties of the quadratic model near the minimizer.The Barzilai and Borwein(BB) gradient method is also an effective method,it can be used for solving large scale optimization problems to avoid the expensive computation and storage of matrices.In addition,the BB stepsize is easy to determine without large computational efforts.In this paper,based on the conic trust region framework,we employ the generalized BB stepsize,and propose a new nonmonotone adaptive trust region method based on simple conic model for large scale unconstrained optimization.Unlike traditional conic model,the Hessian approximation is an scalar matrix based on the generalized BB stepsize,which resulting a simple conic model.By adding the nonmonotone technique and adaptive technique to the simple conic model,the new method needs less storage location and converges faster.The global convergence of the algorithm is established under certain conditions.Numerical results indicate that the new method is effective and attractive for large scale unconstrained optimization problems.     

A time integration procedure for plastic deformation in elastic-viscoplastic metals

A simple unconditionally stable numerical procedure for time integration of the flow rule for large plastic deformation of an elastic-viscoplastic metal is developed. Specific attention is focused on a unified set of constitutive equations which represents a generalization (for large deformation and thermomechanical response) of the Bodner-Partom model [6, 7]. An analytical solution is obtained for large deformation simple shear at constant shear rate. Numerical examples of simple shear, a corner test exhibiting the transition from uniaxial compression to shear, and simple tension are considered which demonstrate the stability and accuracy of the procedure. It is shown that the same procedure can be used for a rate insensitive metal characterized by a yield function as well as for a rate sensitive metal characterized by an overstress model. Finally, an appendix is provided which records the basic equations associated with the small deformation theory.     

Combustion regimes subsequent to the reflection of a detonation from a perforated plate

A simple phenomenological approach is used to elucidate different combustion processes resulted from the interaction of a detonation with a perforated plate. The mathematical model is given by a simple nonlinear logistic difference equation, with parameters associated with the effect of turbulence, quenching and gasdynamics. Different nonlinear solutions of the logistic difference model provide an analog to the possible combustion regimes and they agree qualitatively with the experimental observations.     

Comparison of electromigration simulation in test structure and actual circuit

With the rapid increase in circuit complexity, accurate reliability simulator is necessary as reliability testing for fabricated circuit is progressively more time and resource consuming. Simple 2D electromigration (EM) simulator has many limitations and most of the 3D EM simulations in the literature are using simple line-via structure which is only part of the real circuit structure. In this paper, a thorough comparison between simple 3D line-via structure model and 3D circuit model under different test conditions is performed using class-AB amplifier as an example, and the results showed that simple line-via structure simulation may not always correctly represent the real circuit failure site.     

System identification of a pick-and-place mechanism driven by a permanent magnet synchronous motor

The main objective of this study is to utilize two dynamic models: a mathematical model and a simple model, to identify a pick-and-place mechanism (PPM) which is driven by a permanent magnet synchronous motor (PMSM). In this paper, Hamilton’s principle is employed to derive the mathematical model, which is a nonlinear differential equation, while Newton’s second law is utilized to derive the simple linear model. In system identification, we adopt the real-coded genetic algorithm (RGA) to find not only the parameters of the PPM, but also the PMSM simultaneously. From the identification simulations and experimental results, it is demonstrated that the identification results of the mathematical model present the better matching with the experimental results of the system.     

A Three-Day Workweek Multiple-Shift Scheduling Model

Compressed workweeks have gained acceptance in many 7-days-a-week operations. This paper provides a multiple-shift workforce scheduling model and a simple algorithm for the 3-day workweek. The model presented here is of practical relevance and the algorithm is intuitive and simple enough to be implemented by hand. A scheduler planning to switch to a 3-day workweek but not certain how to schedule off-days and shifts, may find this paper helpful.     

基于LS-SVM的管道腐蚀速率灰色组合预测模型

为提高管道腐蚀速率预测精度,建立了一种基于最小二乘支持向量机的灰色组合预测模型.以各种灰色模型对管道腐蚀速率的预测结果作为支持向量机的输入,以管道腐蚀速率的实测值作为支持向量机的输出,采用最小二乘支持向量机回归算法和高斯核函数对支持向量机进行训练,利用训练好的支持向量机进行组合预测.预测模型兼具灰色模型所需原始数据少、建模简单、运算方便的优势和最小二乘支持向量机具有泛化能力强、非线性拟合性好、小样本等特性,弥补了单一预测模型的不足,避免了神经网络组合预测易于陷入局部最优的弱点.模型结构简单、实用,仿真结果验证了其有效性.     

Modeling a swimming fish with an initial boundary value problem: Unsteady maneuvers of an elastic plate with internal force generation

In order to model unsteady maneuvers in swimming fish, we develop an initial-boundary value problem for a fourth-order hyperbolic partial differential equation in which the fish's body is treated as an inhomogeneous elastic plate. The model is derived from the three-dimensional equations of elastic dynamics, and is essentially a simple variant of the classical Kirchhoff model for a dynamic plate. The model incorporates body forces generating moment to simulate muscle force generation in fish. The initial-boundary value problem is reduced to a beam model in one spatial dimension and formulated computationally using finite differences. Interaction with the surrounding water is represented by nonlinear viscous damping. Two example applications using simple but physically reasonable physiological parameters are presented and interpreted. One models the acceleration from rest to steady swimming, the other a rapid turn from rest.     

A novel recurrent nonlinear neural network for solving quadratic programming problems

This paper presents a new neural network for solving quadratic programming problems. The new model has a simple form, furthermore it has a good convergence rate with a less number calculation operation than the old models. It converges very fast to exact solution of the dual problem and by substituting in a formulation, the optimal solution of the original problem is obtained. Neural network model with one of numerical method is solved. Finally, simple numerical examples are provided for more illustration.     

蠓的线性判别

本文在没有任何假设的条件下，建立了一个对蠓分类的数学模型．所用理论工具、计算工具都很简单，且经反馈检验，对已知种类的蠓模型判断完全正确．     

Lattice Boltzmann method for slip flow heat transfer in circular microtubes: Extended Graetz problem

Slip flow heat transfer in circular microtubes is of fundamental interest and practical importance. However, to the best knowledge of the present author, there is no open publication of developing simple and efficient lattice Boltzmann (LB) models on such topic. To bridge the gap, in this paper a simple LB model, which is based on our recent work [S. Chen, J. Tölke, M. Krafczyk, Simulation of buoyancy-driven flows in a vertical cylinder using a simple lattice Boltzmann model, Phys. Rev. E 79 (2009) 016704], is designed. In addition, the recently developed Langmuir slip model [S. Chen, Z.W. Tian, Simulation of thermal micro-flow using lattice Boltzmann method with Langmuir slip model, Int. J. Heat Fluid Flow 31 (2010) 227-235], which possesses a clear physical picture and keeps the Reynolds analogy, is extended to capture velocity slip as well as temperature jump in microtubes. The feasibility and capability of the present model are validated by the extended Graetz problem, which is a benchmark prototype for forced convection heat transfer in circular microtubes.     

关于Simmons模型的几点讨论

本文介绍了Simmons模型的参数选择方法 ,并对几种Simmons模型的精度、合作程度进行了比较 ,最后推荐一种新的随机化装置 ,不仅在精度上有所提高 ,而且操作简便 ,提高了被访者的合作程度     

资产价值服从跳-扩散过程的风险债券定价

作为对结构化模型和简化模型的改进,本文将结构化模型和简化模型两者融合后提出了一种特殊的跳-扩散过程.在假设公司价值服从这一类跳-扩散过程的情况下,建立了公司风险债券价值所满足的方程,并利用鞅方法得到了公司债券的定价公式.     

评测试卷命题质量的数学模型

运用模糊数学和数理统计理论,以各级评测指标及主要观测点的观测值,是否偏离正常的取值区间为评判要点,着重考察试卷对正常区间的偏离程度,严格控制试卷的异常为重点.由此构建了评测试卷命题质量的科学而适用的数学模型.经过多次实践,该模型具有结构简洁、观测面宽、计算简捷、操作方便、结论可靠等特点,具有适用与推广价值.     

Properties of simple model problems for reacting gas flows

The compressible Navier–Stokes equations for reacting gases are extremely complex. Simpler models have been considered, and for these completely non-physical propagation speeds have been observed. These model problems are stiff, meaning that several different scales are present in the solution. Numerical solution of non-reacting flows almost always involves addition of extra dissipation. It will be shown that this action will render a totally wrong propagation speed for a simple model equation of reacting flows. This problem will be accentuated by increasing stiffness of the problem. Existence and uniqueness of a solution to this model equation is proved. The dependence of the propagation speed on the viscosity and a term governing the stiffness (comparable to the reaction rate for a more complete model) is investigated. A remedy for the wrong propagation speed for this simple model equation is proposed such that the speed is correct although the front is smeared out.     

A model equation for Non-Newtonian fluids

A one-dimensional model for the equations of motion of a “simple fluid” according to Noll is proposed. An exterior problem for the model equation is solved by means of a transform method.