Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows

The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in con-junction with heat transfer enhancement in particle-laden turbulent flows.The effects of particles on momentum and heat transfer are analyzed,and the possibility of drag reduc-tion in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed.We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow,which shows the heat transfer reduction when large inertial parti-cles with low specific heat capacity are added to the flow. However,we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved.The present results show that particles,which are active agents,interact not only with the velocity field,but also the temperature field and can cause a dissimilarity in momentum and heat transport.This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of par-ticles with different thermal properties.     

Discrete Risk Model Revisited

In this paper, the fully discrete risk model is considered. Claim sizes are assumed to be integer-valued. A new method is employed to derive some explicit formulas of the Gerber-Shiu penalty function. Characteristic equations corresponding to recursive equations satisfied by Gerber-Shiu penalty function are analyzed and explicit expressions of the penalty function are then obtained. As a special case, the probability of ruin is obtained. National Natural Science Foundation of China(10571092,10271062)     

On the characteristic functional of a doubly stochastic Poisson process: Application to a narrow-band process

The characteristic functional (c.fl.) of a doubly stochastic Poisson process (DSPP) is studied and it provides us the finite dimensional distributions of the process and so its moments. It is also studied the case of a DSPP which intensity is a narrow-band process. The Karhunen–Loève expansion of its intensity is used to obtain the probability distribution function and a decomposition of this Poisson process. The covariance derived from the general c.fl. is applied in this particular DSPP.     

Investigation of the characteristic energy losses of platinum (111)

With the help of a combined LEED- and Auger-investigation, the surface of a platinum (111) crystal was cleaned first. Then, the spectrum of the characteristic energy losses for both contaminated and cleaned surfaces is studied. On the cleaned surface the following losses were found: ΔE ₁=7.4 eV, ΔE ₂=13.5 eV, ΔE ₃=24.8 eV, ΔE ₄=31.8 eV, ΔE ₅=45.1 eV, ΔE ₆=54.1 eV, ΔE ₇=71.2 eV. The present results are compared with the measurement of other investigators. In particular, in good agreement with optical measurements we identify ΔE ₁ and ΔE ₂ as interband transitions, and ΔE ₃ and ΔE ₄ as surface and volume plasma loss, respectively.     

球对称分布一些子类的特征函数

本文用统一的方法给出了对称Kotz型分布,多元PearsonⅡ分布和椭球logistic对称分布.我们的结果是Iyenger and Tong的结果的推广,另外我们得到了PearsonⅡ型的特征函数的另一种形式.同时,我们讨论了相关的问题.     

Root n bandwidths selectors in multivariate kernel density estimation

Based on a random sample of size n from an unknown d-dimensional density f, the problem of selecting the bandwidths in kernel estimation of f is investigated. The optimal root n relative convergence rate for bandwidth selection is established and the information bounds in this convergence are given, and a stabilized bandwidth selector (SBS) is proposed. It is known that for all d the bandwidths selected by the least squares cross-validation (LSCV) have large sample variations. The proposed SBS, as an improvement of LSCV, will reduce the variation of LSCV without significantly inflating its bias. The key idea of the SBS is to modify the d-dimensional sample characteristic function beyond some cut-off frequency in estimating the integrated squared bias. It is shown that for all d and sufficiently smooth f and kernel, if the bandwidth in each coordinate direction varies freely, then the multivariate SBS is asymptotically normal with the optimal root n relative convergence rate and achieves the (conjectured) lower bound on the covariance matrix.Part of the research was done while the first author was visiting the Institute of Statistical Science, Academia Sinica, Taipei, Taiwan. This work was supported by grant NSC-89-2118-M-006-011, NSC-90-2118-M-006-013 and NSC-91-2118-M-006-005 of National Science Council of Taiwan, R.O.C.     

A fixed point localization formula for the Fourier transform of regular semisimple coadjoint orbits

Let be a Lie group acting on an oriented manifold M, and let ω be an equivariantly closed form on M. If both and M are compact, then the integral is given by the fixed point integral localization formula (Theorem 7.11 in Berline et al. Heat Kernels and Dirac Operators, Springer, Berlin, 1992). Unfortunately, this formula fails when the acting Lie group is not compact: there simply may not be enough fixed points present. A proposed remedy is to modify the action of in such a way that all fixed points are accounted for.Let be a real semisimple Lie group, possibly noncompact. One of the most important examples of equivariantly closed forms is the symplectic volume form dβ of a coadjoint orbit Ω. Even if Ω is not compact, the integral exists as a distribution on the Lie algebra . This distribution is called the Fourier transform of the coadjoint orbit.In this article, we will apply the localization results described in [L1,L2] to get a geometric derivation of Harish-Chandra's formula (9) for the Fourier transforms of regular semisimple coadjoint orbits. Then, we will make an explicit computation for the coadjoint orbits of elements of which are dual to regular semisimple elements lying in a maximally split Cartan subalgebra of .     

模糊控制器动态性能的改善

模糊逻辑控制具有算法简单、鲁棒性强等特点，但动态响应品质不易改善：瞬志响应与稳态特性难于兼顾。本文从工程实践中总结出一种可行的模糊控制算法，基于此算法开发出的模糊控制器响应迅速、调节精细，小批量推广应用的效果令人满意。     

带下降方向搜索的总极值方法

本文将文[1]提出的一类求总极值方法与非线性规划的下降方法相结合,提出一类带下降方向搜索的求总极值方法,并且证明了这类方法具有线性和超线性收效率.     

典型域上R—W多项式及内函数的存在性

该文给出了多复变四类典型域（m，n）,（n）,(2k),（3）及(n)上的R－W型多项式,并证明了这些区域上内函数的存在性．