Applying local model approach for tidal prediction in a deterministic model

In recent years, a practice of tidal prediction based on a deterministic model or by a time series forecasting model has been established. A deterministic model can predict tidal movement and capture the dynamics of the flow pattern over the entire domain. However, due to the simplification of model settings and near shore effects, the accuracy of the numerical model can diminish. Time series forecasting is capable of capturing the underlying mechanism that may not be revealed in the deterministic model simulation. However, such data‐driven forecast fails to maintain accuracy with the progress of forecast horizon. In this paper, a scheme that combines the advantages of these two methods is introduced. The model errors are forecasted to different time horizons using a data‐driven approach, and are then superimposed on the simulation results in order to correct the model output. Based on the proposed method, it is found that the accuracy is significantly improved with more than 50% of the errors removed on the average. Copyright © 2008 John Wiley & Sons, Ltd.     

Dielectric and Pyroelectric Properties of Compositionally Graded Pb(Zr1-xTix)O3 Thin Films Prepared by Sol-gel Process

"Compositionally graded ferroelectric lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process. The final structure consists of six layers, up-graded graded films starting from PbZrO3 on the Pt electrode to the top PZT(50) layer, it consists of no Ti, 10%Ti, 20%Ti, 30%Ti, 40%Ti, and 50%Ti respectively. Whereas films with opposite gradient are called down-graded graded films. Structure and dielectric properties of the graded films was investigated by X-ray diffraction, Auger electron spectroscopy and by impedance analysis. The up-graded and down-graded PZT films annealed at 600 o, exhibited the remanent polarization values of 18.0 and 24.2 1C/cm2, respectively. The typical small signal dielectric constants and loss tanffi at a frequency of 100 Hz were 523 and 0.018, 544, and 0.020, respectively, for up-graded and down-graded PZT thin films. The temperature dependence of pyroelectric coeoients of the graded PZT films was measured by a dynamic technique. From 20 o to 82 o, the pyroelectric coeoients of the up-graded and down-graded PZT films up to 374 and 407 1C/m2K, respectively."     

Initiated Chemical Vapor Deposition of Poly(furfuryl methacrylate)

Furan ring‐functionalized solid surfaces are achieved by the initiated chemical vapor deposition (iCVD) method, a solvent‐free process to form films under mild conditions. The polymerization of furfuryl methacrylate monomer is initiated by a resistively heated filament wire. The functionality of the furan group in the iCVD film enabled Diels–Alder chemistry with 4‐phenyl‐1,2,3‐triazolin‐3,5‐dione (N‐PTD).

     

CONVERGENCE OF NEWTON＇S METHOD FOR A MINIMIZATION PROBLEM IN IMPULSE NOISE REMOVAL

Recently, two-phase schemes for removing salt-and-pepper and random-valued impulse noise are proposed in [6, 7]. The first phase uses decision-based median filters to locate those pixels which are likely to be corrupted by noise (noise candidates). In the second phase, these noise candidates are restored using a detail-preserving regularization method which allows edges and noise-free pixels to be preserved. As shown in [18], this phase is equivalent to solving a one-dimensional nonlinear equation for each noise candidate.One can solve these equations by using Newton‘s method. However, because of the edgepreserving term, the domain of convergence of Newton‘s method will be very narrow. In this paper, we determine the initial guesses for these equations such that Newton‘s method will always converge.     

Effect of Turbulent Flow on Coil‐Globule Transition of λ‐DNA

Summary: The addition of spermidine (SPD) into turbulent flow as a condensing agent showed the abrupt change of turbulent drag reducing (DR) efficiency of λ‐DNA in turbulent flow for the first time. The resultant asymptote DR efficiency explains the origin of those changes, which can be conclusively verified via the electrophoresis experiment. Despite the different fluid conditions, with and without condensing agent, all λ‐DNA molecules possessed the same half‐cut dimension, implying that the discrete change of DNA conformation can dramatically alter the flow characteristics.

Coil‐globule transition of DNA by spermidine.     

耐高温邻苯二甲腈树脂研究进展

邻苯二甲腈树脂是以邻苯二甲腈结构封端的高性能耐高温热固性树脂,具有优异的热氧稳定性、阻燃性、力学强度、低吸水率、低热膨胀系数和介电常数,可用于制备先进复合基体材料、涂料、粘接剂等,在航空技术、电子、机械、军事等领域得到广泛应用.本文综述了邻苯二甲腈树脂结构、邻苯二甲腈单体类型、邻苯二甲腈的固化剂、自催化邻苯二甲腈、生物...     

Fly Cheaply: On the Minimum Fuel Consumption Problem

In planning a flight, stops at intermediate airports are sometimes necessary to minimize fuel consumption, even if a direct flight is available. We investigate the problem of finding the cheapest path from one airport to another, given a set of n airports in ² and a function l: ² × ² → ⁺ representing the cost of a direct flight between any pair. Given a source airport s, the cheapest-path map is a subdivision of ² where two points lie in the same region iff their cheapest paths from s use the same sequence of intermediate airports. We show a quadratic lower bound on the combinatorial complexity of this map for a class of cost functions. Nevertheless, we are able to obtain subquadratic algorithms to find the cheapest path from s to all other airports for any well-behaved cost function l: our general algorithm runs in O(n^{4/3 +} ) time, and a simpler, more practical variant runs in O(n^{3/2 +} ) time, while a special class of cost functions requires just O(n log n) time.     

陶瓷/VDF-TrFE 0-3型铁电复合物的三阶非线性介电系数

在自建的非线性介电测试装置上测得了Ｐ笔ＶＤＦ－ＴｒＦＥ共聚物形成的０－３型铁电复合物厚片的三阶非线性介电系数ε３。研究发现,三种复合物的ε３都随陶瓷组分含量的上升而增大,测试场强升高,测得的ε３值减小,但对高陶瓷含量（Φ〉０．０４）的ＢＴ／ＶＤＦ－ＴｒＦＥ和ＰＺ／ＶＤＦ－ＴｒＦＥ复合物则在６ＭＶ／ｍ场强下出现极小值,二相都被预极化的复合物小于仅陶瓷相被预极化的ε３值,ＰＺＴ／ＶＤＦ－ＴｒＦＥ复合物     

圆锥形血管中的振荡发展流动

本文在小锥度角的假设下,研究了圆锥形血管的非定常振荡的发展流动问题.导得了相应的速度分布公式.分析表明,所有收缩的圆锥形血管的流动都是发展流动,而且锥度角对发展流动的影响随着锥度角的增大而增大.