The Study on Pipe Sudden Enlargement Local Resistant Coefficient

During the design of pipeline,the determination of local resistent coefficient is often come arcoss.The sudden enlargement local resistant coefficient ξ1=[1-A1/A2]^2 is determined through theory.In the paper,the sudden enlargement local resistant coefficient under the conditions of three kinds of A1/A2 was studied in experiment.In the end,the result shows that ξ1 is related not only to two flow cross sections,but also to the velocity.Thyough experimental research,the relationship between ξ1,A1/A2 and V1 was determined.In a word,the hydraulic calculation of pipeline can be done by taking correspondent ξ1,according to the design velocity V1 and A1/A2.     

一类抽象半线性泛函微分方程的小时滞鲁棒稳定性

研究Banach空间X中的抽象半线性泛函微分方程d/dtx(t) = Ax(t)+F(t, x_t(·))的小时滞鲁棒稳定性,其中无界线性算子A在X上生成一个C0-半群T(t)_t≥0, F是非线性函数.在F是全局Lipschitz连续的条件下,利用算子半群理论以及扰动方法,证明了上述方程的解的指数稳定性对小时滞是鲁棒的.

Abstract：

The robust stability of the abstract semi-linear functional differential equationd/dtx(t)= Ax(t)+F(t, x_t(·))is considered in Banach space X, where the linear operator A generates a C_0-semigroup [T(t)]_t≥0in X, and F is a nonlinear function. Under the condition that F is globally Lipschitz continuous, and the robust stability of the above equation is proved with the operator semi-group theory and perturba-tion method.     

一类具有特殊曲率性质的(α,β)-度量

在一般的(α,β)-度量F=αφ(s)与Riemann度量α的Ricci曲率之间的关系基础上,证明了一类特殊的(α,β)-度量F=α~2/α+β南,在维数n≥3的流形上,如果F具有速向的Ricci曲率,且β是闭的1-形式,则其Ricci曲率等于零.从而得到如果F=α~2/α+β具有常Ricci曲率,并且β是闭的1-形式,则其Ricci曲率等于零.

Abstract：

We studied an important class of(α,β)-metric on the basis of the relationship of Ricci curvature between G1and a Gi.We verified that if F=α~2/α+β on an n dimension manifold M(n≥3)is of istropic Ricci curvature,i.e.Rmm=(n-1)c(x)F~2,where c(x)is a scalar function on M and β is closed 1-form,then c(x)=0.Hence,we obtained that if F=α~2/α+β is of constant Ricci curvature and β is closed,then c(x)=0.     

Cardinal temperatures and required biological days from sowing to emergence of three millet species （common,foxtail, pearl millet）

The modeling of germination and seedling emergence is required for the construction of a simulation model of three species of millet （panicum miliaceum, pennisetum galucum and setaria italica）. This study provides the necessary temperature parameters to model these processes. For this purpose, different non-linear regression models including fiat, logistic, quadratic, sigmoidal, dent-like, segmented, beta and curvilinear were used. Root Mean Square of Errors, coefficient of determination and regression coefficients of predicted values versus observed were used to find the appropriate model. Investigating regression coefficients indicated that dent-like model has the least RMSE and a coefficient （RMSE=0.000009, a=0.0006） and the biggest R2 and b coefficient （R2=0.96, b=0.98） in common millet. These coefficients were （RMSE=0.01, a=0.005） and （R2=0.94, b=0.97）, and （RMSE=0.004, a=0.05） and （R2=0.99, b=0.99）, for beta in foxtail and pearl millet, respectively. According to these coefficients, dent-like, was chosen as the best model to describe the response of common millet germination to temperature （Tb=7~C and Tc=49.50℃）. Also beta, was chosen for foxtail millet （Tb=7℃, Tc=49.50℃）. Beta, was chosen as the best model for pearl millet （Tb=6.5 ℃ and To=4 ℃ ）. These parameters can be used in millet simulation models to predict sowing to emergence duration based on a thermal time concept. Also, required biological days from sowing to emergence using these models varied from 3.57, 4.29 and 5.54, for common millet, foxtail millet and pearl millet, respectively.     

数值求解对流方程的一族三阶精度差分格式

在6个节点基础上应用组合差商方法构造了求解对流方程的一类差分格式,该类差分格式包括了一个隐式差分格式和一个半显差分格式,这两个格式均由包括6个节点的两组线性无关的差商构成,具有精度高、相对误差很小、计算简单、工作量少、编程简便等优美特点.详细地分析了差分格式的稳定性,给出了两个数值实例,并对实例中的误差做了图表展示.

Abstract：

A new group of compact difference schemes containing three parameters of the third order is given for the convection problems with constant coefficient. These difference schemes contain an implicit difference scheme and a semi-significant difference scheme. Both schemes consist of two difference quotients, each containing 6 nodal points. This method is characterized by high accuracy, small relative error [their truncation error is as low as O(τ~3 +h~3)], simplicity in calculation, low workload and convenience in writing programs. The scheme is applicable for solving convective equations with constant coefficients.     

一阶变系数线性微分方程系统的Hyers-Ulam稳定性

通过基解矩阵的指数二分性证明了一阶变系数微分方程的Hyers-Ulam稳定性,推广了已有结论.

Abstract：

S. M. Jung investigated the Hyers-Ulam stability of a system of first order linear differential equations with constant coefficients by discussing the eigenvalues of matrix. Using the exponential dichotomy of fundamental solution matrix, this paper proves the Hyers-Ulam stability of first-order differential equations with variable coefficients and generalizes the previous conclusions.     

对称偏导数

1　Symbols and DefinitionDefinition 1　 Suppose that the function　 y=f (x) is defined in an open interval (a,b) ,x∈(a,b) iflimΔx→ 0f (x +Δx) - f (x -Δx)2Δxexists,the limit is called the symmetric derivative of f(x) at point x,and denoted bydsfdx.Definition2　 Suppose that the function f(x,y) is defined for in a neighborhood of point M(x,y) .IflimΔx→ 0f (x +Δx,y) - f (x -Δx,y)2Δxexists,the limit is called the symmetric partial derivative of f (x,y) with respect to x at M,anddenote…     

一类参数不确定广义时滞系统的H∞保性能鲁棒控制

针对一类状态时滞的参数不确定性广义系统,讨论了它的保性能控制问题.目的是对状态时滞的参数不确定广义系统,提出它的时滞无关保性能鲁棒控制器的一个设计方法.首先给出了广义时滞系统正则、脉冲自由且稳定的严格线性矩阵不等式表示的时滞无关充分条件;然后采用线性矩阵不等式方法,给出参数不确定性广义时滞系统的时滞无关保性能控制问题可解的一个严格线性矩阵不等式表示的充分条件,在此条件可解时,给出了时滞无关保性能鲁棒控制器表达式,以及相应的可保性能指标.最后给出了所提出方法的应用.

Abstract：

The guaranteed cost control problem is studied for singular systems with time-delay and parameter uncertainty in order to design a delay-independent guaranteed cost controller for singular systems with time-delay and parameter uncertainty. First, a delay-independent sufficient condition is derived, which is expressed by strict linear matrix in-equality (LMI) for singular systems with time-delay to be regular, impulse free and stable. Then, the delay-independent sufficient condition for the existence of guaranteed cost controller is given in terms of strict linear matrix inequalities via LMI approach. When these LMI are feasible, an explicit expression of delay-independent robust guaranteed cost controllers and the corresponding guaranteed cost of the systems are obtained. Finally, a numerical example is provided to demonstrate the application of the proposed method.     

Photosynthetic Responses of A New Grapevine Variety ‘Xinyu’ in Turpan

Turpan is one of the major high-quality grape production bases in the world for years because its climate is so special (hot, dry, and windy). The grape market needs the varieties with high yield, quality, and environmental adaptability. ‘Xinyu’ is a new variety bred by crossing selection of E42-6 (a self-pollinated inbred of Vitis vinifera cv. ‘Red Globe’) as female and Vitis vinifera cv. ‘Rizamat’ as male parents and registered in the Crop Varieties Registered Commission of Xinjiang Uygur Autonomous Region in 2005. In this study, we determined the impacts of environmental factors on its photosynthesis. The results showed the climate in Turpan was characterized by long-time intensive sunshine, high temperature and relatively low humidity. The peak value of photosynthetic available radiation (PARi) was 1 454 μmol·m^-2·s^-1, and the minimum and average values were 111 μmol·m^-2·s^-1and 938.889 6 μmol·m^-2·s^-1, respectively. Air temperature and sunlight intensity reached the highest values during 1 p.m. to 4 p.m. Net photosynthetic rate (Pn) of Xinyu increased stably before 11 a.m. and there was a midday depression during 11 a.m. to 2 p.m. The minimum value of Pn appeared at noon (2.77 μmol·m^-2·s^-1). It was concluded that as a new grape cultivar, “Xinyu” could withstand extreme climate conditions in Turpan.