Steady viscoelastic film flow over 2D topography: I. The effect of viscoelastic properties under creeping flow

Two-dimensional, steady flow of a viscoelastic film over a periodic topography under the action of a body force is studied. The exponential Phan-Thien and Tanner (ePTT) constitutive model is used. The conservation equations are solved via the usual mixed finite element method combined with a quasi-elliptic grid generation scheme in order to capture the large deformations of the free surface. The constitutive equation is weighted using the SUPG method and solved via the polymeric stress splitting EVSS-G technique. First, the code is validated by verifying that in isolated topographies the periodicity conditions result in fully developed viscoelastic film flow at the inflow/outflow boundaries and that its predictions for Newtonian fluids over 2D topography under creeping flow conditions coincide with those of previous works. Since the lubrication approximation is not invoked here, the topographical features can have wall segments that form any angle with the main flow, but only slight smoothing of the convex corners assists in reducing the stress singularity there. Thus, steady-state solutions are computed accurately up to high Deborah numbers, resulting in large deformations of the free surface. The magnitude of the capillary ridge in the film before the entrance to a step down of the substrate and of the capillary depression before a step up is increased as De increases up to ～0.7 due to increased fluid elasticity. Above this value they decrease, because increasing De increases also the shear and elongational thinning, which eventually affect them more. Increasing the ratio of solvent to polymer viscosities, β, the elongational parameter, ? and the molecular slip parameter, ξ, monotonically increases their magnitudes and especially that of the capillary ridge, but the mechanisms leading to these changes are different as explained in the text.     

Solubility and stability of recurrent neural networks with nonlinearity or time-varying delays

Because to apply a deterministic RNN to a noisy time series and the existence of a linear approximation are doubtful, we reconsider the solubility and stability of a recurrent neural network (RNN). Simpler methods are proposed to replace the complicated nonsingular M-matrix method when nonlinearities exist and to replace the complicated linear matrix inequality method when time-varying delays exist.     

Design and application of feedback-sustained target waves in excitable medium

In this paper, we present a formulas of rational ratios between the frequency of external stimulus and its paced target waves, considering the existence of the absolute refractory period and the relative refractory period. Based on this, we design a self-sustained high-frequency target waves by feeding back few periphery field points to the center to responsibly play the role of source for pacemaker. Such constructed target waves, to all appearances, are shown as a repetition of their initial condition. We explore further in application that those feedback-sustained targets can eliminate both a freely rotating spiral waves and a pinned ones only if frequencies, feedback lengths and radius of obstacles are appropriately chosen. After feedback stimuli are removed, the system eventually returns to the rest state.     

Preparation and characterization of the antimony telluride hexagonal nanoplates

Nanostructured thermoelectric materials are of much interest for improving the thermoelectric figure of merit. In the present work, Sb₂Te₃ hexagonal nanoplates were successfully fabricated via a facile hydrothermal method. The products were characterized by means of X-ray diffraction, field-emission scanning electron microscope, transmission electron microscope and energy-dispersive X-ray spectroscopy. The results show that the typical Sb₂Te₃ crystal is hexagonal in shape with about 35 nm in thickness and 300 nm in edge length. The mechanism for formation of Sb₂Te₃ hexagonal nanoplates is primarily discussed.     

Multi-radius centralized projection for binary pattern histogram face recognition

The existing local binary pattern （LBP） operators have several disadvantages such as rather long histograms, lower discrimination, and sensitivity to noise. Aiming at these problems, we propose the central- ized binary pattern （CBP） operator. CBP operator can significantly reduce the histograms＇ dimensionality, offer stronger discrimination, and decrease the white noise＇s influence on face images. Moreover, for in- creasing the recognition accuracy and speed, we use multi-radius CBP histogram as face representation and project it onto locality preserving projection （LPP） space to obtain lower dimensional features. Experiments on FERET and CAS-PEAL databases demonstrate that the proposed method is superior to other modern approaches not only in recognition accuracy but also in recognition speed.     

序Banach空间中一类算子方程的可解性

利用改进的Mnch紧性条件,研究了一类算子方程Lx=Nx的解的存在性．本文结果并没有要求算子L和N的连续性．作为应用,讨论了右端项不连续的隐式椭圆偏微分方程的边值问题的解的存在性．     

保险联结风险投资模型的赤字问题

保险公司被允许将部分资金投入风险市场,这样保险公司经营的风险来自于未来实际发生索赔的不确定性和投资收益的不确定性。研究了由经典的Cramer-Lundberg模型与按照几何布朗运动股票价格变动的一个风险模型,获得了三种资产分配情况下股票价格波动对赤字发生概率下界的影响。     

Bazilevic函数相邻两系数模之差的估计

本文研究单叶函数相邻系数模之差的增长问题,设f(z)∈S, 0<λ<1．当f为Bazilevic函数时,得到||Dn+1|-|Dn||的准确的阶的估计．     

Optimal birth control of age-dependent competitive species : II. Free horizon problems

We study optimal birth policies for two age-dependent populations in a competing system, which is controlled by fertilities. New results on problems with free final time and integral phase constraints are presented, and the approximate controllability of system is discussed.