This paper discusses the problem of integral factor about the first order constant differential equation: (M(x,y)dx+N(x,y)dy)=0, gives a sufficient and necessary condition of integral factor such as μ(ax~α+bx~sy~l+cy~β) for first order ordinary differential equation, and makes an extension form the conclusion of related reference.
The 3D SEM BPM reduces the basic BPM equation to the first order normal differential equation system. Consequently,the computational program is simple.
Three dimensional beam propagation method based on the series expansion method(3D SEM BPM) transform the BPM into the first order normal differential equations. The method has the merits of simple calculation and high calculation efficiency.
三维级数展开的光束传播法 (3D SEM BPM )将BPM方程转化为一阶常微分方程组 ,具有计算方法简单和计算效率高的优点。
The mathematical model about the various structures room is synthesized together , on this foundation,the instantaneous energy of the room was balanced,and the normal differential coefficient –partial differential coefficient equation model about the temperature response to the room with walls built with composite material was built,and finds the solution to mathematical method of this model.
In this paper,in order to discuss the sustainable exploitation problem of forest resource on the premise of providing ecological production to the society, the dynamic economic model of sustainable exploitation of forest resource is built up on the basis of the maximal sustainable utilization principle for the exploitation and utilization of ordinary biology resources,and the optimal resource retainable yield and optimal exploitation strategy are calculated by the mathematical methods such as normal differential function,variational method,maximum principles and so on.
The method converts the frame problem into a set of ordinary differential equations using concepts from classical mechanics and orthogonal group techniques.
On the existence of periodic solutions for the third-order nonlinear ordinary differential equations
In this paper, the existence of periodic solution for the third-order nonlinear ordinary differential equation of the form {} is considered, where f, g, h and p are the continuous functions, and p(t+T)=p(t).
Uniqueness of positive solutions of a class of quasilinear ordinary differential equations
Uniqueness results are obtained for positive solutions of a class of quasilinear ordinary differential equations.
The voltage-current characteristics of a superconducting contact of submicrometer size between two monocrystalline filaments (of Sn, In, and Zn) show linear portions with discrete values of constant differential resistance.
PCD systems are dynamical systems defined by a piecewise constant differential equation and can be considered as computational machines working on a continuous space with a continuous time.
The results of angular distributions are presented in the form of contours of constant differential cross sections as well as in the form of differential cross section surfaces in three-dimensional plots.
Finally, we show that morphological operators used in image processing are particular cases of operators induced by constant differential inclusion.
At voltages Vdc 4 meV a constant differential resistance is found.
It is shown that the stream function and temperature are uniformly convergent series, the terms of which satisfy an infinite system of normal differential equations.
Transformations between two normal differential equations.
The hydronephrotic kidney usually has nearly normal differential renal function at birth, has not been subjected to progressive dilation and except for pelvocaliectasis does not often show signs of high-grade obstruction.
An infant with an asymptomatic unilateral hydronephrosis of any grade, without urinary infection and stable washout, and stable normal differential function on serial controls can be managed conservatively.
Initial hematocrit was 25.7%; white blood cell count 14,000 cu/mm with a normal differential; platelet count 532,000 cu/mm.
A theoretical analysis of the laminar flow in the annular space bounded by two concentric tubes with small injection and suction through the porous walls is presented in this paper. By using a similarity transformation, the Navier-Stobes equations in the cylindrical co-ordinates for the steady incompressible flow are reduced to an ordinary non-linear differential equation of the third order. With appropriate boundary conditions, this equation is solved by the method of small perturbation. The results show that...
A theoretical analysis of the laminar flow in the annular space bounded by two concentric tubes with small injection and suction through the porous walls is presented in this paper. By using a similarity transformation, the Navier-Stobes equations in the cylindrical co-ordinates for the steady incompressible flow are reduced to an ordinary non-linear differential equation of the third order. With appropriate boundary conditions, this equation is solved by the method of small perturbation. The results show that the velocity of injection or suction and the two radii of the annulus affect considerably the velocity profile, the pressure drop in the flow direction and the friction coefficients at the walls. When the suction is applied only at the inner tube the position of the maximum velocity moves inward. The friction at the inner wall consequently increases and that at the outer wall decreases. It is also found that in the case considered the suction reduces the pressure drop in the flow direction.
This method of the transportation along a cable is found by laborers of our nation when transport soil during their participating in hydraulic engineering constructions of large type. The method is to rack up two cables along the slope of a hill parallel each other, Between the cables a fixed pulley is hanged. A string surround the pulley. Two boxes C and D, prepared for containing the soil, is tied up at each end of the string When the box, say C, full of soil, slides down along the cable from above by gravity,...
This method of the transportation along a cable is found by laborers of our nation when transport soil during their participating in hydraulic engineering constructions of large type. The method is to rack up two cables along the slope of a hill parallel each other, Between the cables a fixed pulley is hanged. A string surround the pulley. Two boxes C and D, prepared for containing the soil, is tied up at each end of the string When the box, say C, full of soil, slides down along the cable from above by gravity, the vacant box D must then ascend up along the other cable simultaneously. Doing thus again and again, the soil is then transported to the bottom of the hill quickly. The distribution of tensions in the perfectly flexible cable, to be encircled tightly on the rough column, has been stated in some texts of mechanics. In this article, considering the mass of the string and the boxes, and the friction between the string and the pulley, and under the condition of inextensibility of the string, we have established a closing system of the non-linear ordinary differential equations which determines the motion of the boxes, and established also the formula for the distribution of tensions in the string in the state of motion.
常微分
ordinary differential
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