Measurement of boiling heat transfer coefficient in liquid nitrogen bath by inverse heat conduction method

Inverse heat conduction method （IHCM） is one of the most effective approaches to obtaining the boiling heat transfer coefficient from measured results. This paper focuses on its application in cryogenic boiling heat transfer. Experiments were conducted on the heat transfer of a stainless steel block in a liquid nitrogen bath, with the assumption of a 1D conduction condition to realize fast acquisition of the temperature of the test points inside the block. With the inverse-heat conduction theory and the explicit finite difference model, a solving program was developed to calculate the heat flux and the boiling heat transfer coefficient of a stainless steel block in liquid nitrogen bath based on the temperature acquisition data. Considering the oscillating data and some unsmooth transition points in the inverse-heat-conduction calculation result of the heat-transfer coefficient, a two-step data-fitting procedure was proposed to obtain the expression for the boiling heat transfer coefficients. The coefficient was then verified for accuracy by a comparison between the simulation results using this expression and the verifying experimental results of a stainless steel block. The maximum error with a revised segment fitting is around 6%, which verifies the feasibility of using IHCM to measure the boiling heat transfer coefficient in liquid nitrogen bath.     

A fractal approximation algorithm for inverse initial-value problems of nonlinear differential equations

1. Introduction Initial-value problems (IVP) for the differential equations are often confronted with in many fields of science, and are particularly common in engineering. These problems are characterized by a governing differential equation and its associated initial conditions. Methods for solving direct IVP have been known for many decades in the area of differential equation. A few of the more popular methods of solution have proven to provide sufficient and even efficient mechanisms …     

具有封闭级数解的热传导方程的初值问题

讨论热传导方程的初值问题级数解的问题.在外部条件具有周期奇偶性的情况下,利用函数延拓的方法,将热传导方程的初值问题转化为不同边界条件的混合问题,从而给出了问题的级数解,说明了混合问题的级数解和初值问题的积分解之间的关系.     

二维非定常跨声速流动的B型反命题:变分理论

A family of variational principles (VP) has been developed for the unsteady inverse problem of the second type IB. It opens new ways for the inverse shape design of unsteady airfoils and can serve as key basis of multipoint inverse shape design of steady airfoils and cascades.     

现场条件下建筑结构的热传递衰减倍数与延迟时间

介绍了2001年夏天对南京某一建筑围护结构的衰减倍数与延迟时间进行现场测试的情况.根据房间的内表面吸热频率响应、内表面温度、室内气温和室外综合温度,可计算出建筑围护结构的衰减倍数与延迟时间.实验结果表明,对于建筑围护结构热传导的衰减倍数与延迟时间,0阶和1阶的现场测试值与理论计算值比较吻合,2阶值则相差很大,因此很难精确测试出2阶值.然而,现场条件下基于1阶以内来分析建筑围护结构的衰减倍数与延迟时间仍然是可行的,因为在计算1阶时建筑围护结构的衰减倍数已达到20,完全可以满足工程要求.     

Solution of an inverse problem for ＂fixed-fixed＂ and ＂fixed-free＂ spring-mass systems

The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring constants from the natural frequencies of the ＂fixed-fixed＂ and ＂fixed-fres＂ spring-mass systems. An example was given to illustrate the results.     

一类Jacobi矩阵特征值反问题的新算法

In this paper, an inverse problem on Jacobi matrices presented by Shieh in 2004 is studied. Shieh’s result is improved and a new and stable algorithm to reconstruct its solution is given. The numerical examples is also given.     

关于中心厄米特矩阵的广义反特征值问题

1　Introduction　AmatrixA∈Cn×missaidtobecentrohermitianifA =Jn AJm,andskewcentrohermitianifA =-Jn AJm,where Adenotetheconjugateofthema trixAandJlisthepermutationmatrixoforderlwithonesonthecrossdiagonal(bottomlefttotopright)andzeroselsewhere .ThehermitianToeplitzmatricesformanimportantsubclassofcentrohermi tianmatriceswhichoccurnaturallyindigitalsignalprocessingandotherareas ,seeforinstance[1] andreferencetherein .Thecentrohermitianandrelatedmatricesrecentlyplayanimportantroleinthesolu…     

采用A-光滑正则化的求解非线性不适定问题的一种Newton 型方法

In this paper we present a regularized Newton-type method for ill-posed problems, by using the A-smooth regularization to solve the linearized ill-posed equations. For noisy data a proper a posteriori stopping rule is used that yields convergence of the Newton iteration to a solution, as the noise level goes to zero, under certain smoothness conditions on the nonlinear operator. Some appropriate assumptions on the closedness and smoothness of the starting value and the solution are shown to lead to optimal convergence rates.     

求解非线性互补问题的两步迭代-Filter方法

利用牛顿迭代法作为预测步,用不动点迭代法作为修正步,结合filter技术,提出了求解非线性互补问题的两步迭代-filter算法,并证明了算法的局部三阶收敛性,最后通过数值实验表明该算法的有效性.     

多约束非线性背包问题的一种有效算法

1IntroductionWe consider the following multi-di mensional nonlin-ear knapsack problem(MNKP)maxf(x)=∑nj=1fj(xj)s.t.gi(x)=∑nj=1gij(xj)≤bi,i=1,…,m,x∈X={x|lj≤xj≤uj,xjinteger,j=1,…,n},where allfjand allgijare nondecreasing functions ofxjon[lj,uj]forj=1,…,n,i=1,…,m,andljandujare integer lower and upper bounds forxj,re-spectively,j=1,…,n.It has been proved that0-1linear knapsack problemis NP-hard[1].Nonlinear knapsack problems have numerous appli-cations in various fields,for example,ca…     

共轭梯度法解一维参数识别问题

考虑一维稳态扩散方程反问题,将问题归结为一个非线性不适定问题后,考虑用共轭梯度法解其对应的最小二乘泛函;数值实验显示该方法有良好的恢复效果。     

Fully Discrete Nonlinear Galerkin Methods for Kuramoto-Sivashinsky Equation and Their Error Estimates

WeconsidertheKuramoto-Sivashinsky(K-S)equationinonespacedimensionwithperiodicboundaryconditionalldzero1lleantwhere110(x)isl-periodicandofzero"lean.TheK-Sequationmodelspatternformationsindifferentphysicalcontexts["3"landisaparadignloflowdimensionalbehaviou…     

Smoothing inexact Newton method for solving P 0-NCP problems

Based on a smoothing symmetric disturbance FB-function, a smoothing inexact Newton method for solving the nonlinear complementarity problem with P0-function was proposed. It was proved that under mild conditions, the given algorithm performed global and superlinear convergence without strict complementarity. For the same linear complementarity problem （LCP）, the algorithm needs similar iteration times to the literature. However, its accuracy is improved by at least 4 orders with calculation time reduced by almost 50%, and the iterative number is insensitive to the size of the LCP. Moreover, fewer iterations and shorter time are required for solving the problem by using inexact Newton methods for different initial points.     

一类变分不等式系统的辅助问题及其算法

研究了一类非线性变分不等式系统(SNVI)及其相关辅助问题,建立了辅助问题解的存在性定理。基于这些辅助问题,构造了求解SNVI的算法,证明了SNVI解的存在性以及算法的收敛性。     

Blow-up and global existence for the heat equation with nonlinear absorption-diffusion

This paper deals with blow-up of positive solution of the nonlinear heat equation with absorption subject to a nonlinear boundary condition.The conditions under which the solutions may exist globally or blow-up are obtained by the comparison principles.     

一类广义鞍点问题迭代解法的收敛性分析

给出一类广义鞍点问题迭代解法的收敛性分析结果,降低了目前已有相关结论的适用条件,因而使得相关结果具有更广泛的应用性．     

A necessary and sufficient condition for positive solutions of singular fourth order boundary value problems

This paper deals with the existence of positive solutions for the singular fourth order boundary value problem.A necessary and sufficient condition for the existence of C3[0,1] positive solution is given by means of the monotone terative technique.Furthermore,the uniqueness of the C3[0,1]positive solution,and the iterative sequence of the C3[0,1]positive solution are also obtained.     

关于反函数的一种积分法及其应用

给出反函数的一种积分法,应用此法,可以将某些类型的不定积分、定积分问题简便地转化为反函数的不定积分、定积分问题求解.     

一类半线性双曲型方程组的柯西问题

讨论一类半线性双曲型偏微分方程组的两种柯西问题,使用毕卡迭代法,获得了关于解的存在唯一性方面的结果.