The characteristic‐based split (CBS) meshfree method for free surface flow problems in ALE formulation

A semi‐implicit characteristic‐based split (CBS) meshfree algorithm in the arbitrary Lagrangian Eulerian (ALE) framework is proposed for the numerical solution of incompressible free surface flow problem in the paper. The algorithm is the extension of general CBS method which was initially introduced in finite element framework, this is due to the fact that CBS method not only can enhance the stability, but also avoid LBB condition when equal order basis function is used to approximate velocity and pressure variables. Meanwhile, a simple way for node update and node speed calculation is developed which is used to capture the free surface exactly. The numerical solutions are compared with available analytical and numerical solutions, which shows that the proposed method has better ability to simulate the free surface incompressible flow problem. Copyright © 2009 John Wiley & Sons, Ltd.     

Combined electric field and near-field scanning optical microscopy: modification of silicon surfaces

Received: 3 July 1998     

Solvent‐induced crystallization in poly(ethylene terephthalate) during mass transport

Solvent transport in poly(ethylene terephthalate) (PET) and related phase transformation were investigated. The data of mass sorption were analyzed according to Harmon's model for Case I (Fickian), Case II (swelling), and anomalous transport. This transport process in PET is accompanied by the induced crystallization of the original amorphous state. The transformation was examined by wide‐angle X‐ray scattering, small‐angle X‐ray scattering, differential scanning calorimetry, and Fourier transform infrared spectroscopy. During this process, the matrix is under a strain state that causes different kinetic paths of crystallization as compared with that by thermal annealing. This state of strain assists the development of the solvent‐induced crystallization. The model regarding crystallization was proposed in terms of the study of long period L, the crystal thickness l_c, and the thickness of amorphous layer l_a obtained from the one‐dimensional correlation function and interface distribution function. Different kinetic paths were discovered for different crystallization processes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1444–1453, 2002     

Optical emission from laser-produced chromium and magnesium plasma under the effect of two sequential laser pulses

Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in emission intensity was noted for inter-pulse delay of ∼2–3 μs for all the elements. The experimental observations were qualitatively explained on the basis of absorption of second laser pulse in the pre-formed (by first laser) coronal plasma by inverse Bremsstrahlung process, which were found responsible for the excitation of more ions and atoms in the plasma. This process starts as the plasma scale length becomes greater than the laser wavelength. This study further indicated the suitability of this technique in the field of elemental analysis     

Shape optimization of coronary artery stent based on a parametric model

The implantation of intravascular stent (IVS) is a kind of coronary angioplasty to restore the blood flow perfusion to the downstream of the heart muscle tissue. The superior mechanical properties of a stent guarantee the successful implantation. This paper intends to improve the mechanical properties of MAC STENT^TM by utilizing optimization theory instead of the conventional trial-and-error approach. In order to achieve this goal, firstly, a reliable procedure of finite element analysis (FEA) is established based on a parametric geometric model. The FEA overcomes the difficulties due to nonlinearities such as elasto-plasticity, large deformation, large strains and contact. It can simulate the stent's deformations during a loading scheme of three phases without any possible failures or irregularities. Secondly, a single objective function, which includes the main mechanical properties of stents, is proposed to replace the initial multi-objective function and then an optimization model is formulated. An optimal design of MAC-J09-3.0 stent is obtained after successful execution of the optimizing process using 41 loops. Its comprehensive mechanical properties are largely improved. It is concluded that the optimization theory is very useful and efficient in the studies of coronary artery stents, although the optimization task encounters many severe difficulties and requires extensive calculation. The result also shows that the single objective function proposed in this paper is practical.     

湖南省城镇居民消费的实证分析

本文利用递归的核回归模型 ,分析湖南省城镇居民消费性支出 ,以提高拟合度 ,减少预测误差     

用于高功率激光装置中的电脉冲整形系统

采用射频GaAs场效应管和微带传输线技术,研制出用于高功率激光装置中的电脉冲整形系统.该系统电脉冲整形宽度为3.5 ns,幅度在0~5 V范围内调节,时域调整精度200 ps.整形后的方波,前沿383 ps,后沿642 ps,顶部不平坦度4~5%,波形幅度稳定性4~5%（p-p).利用该系统产生的整形电脉冲驱动电光波导调制器进行激光脉冲整形,得到了理想的整形激光脉冲.     

Direct olive oil analysis by low‐temperature plasma (LTP) ambient ionization mass spectrometry

A fast, reagentless, and direct method is presented for the mass spectrometric analysis of olive oil without any sample pretreatment whatsoever. An ambient ionization technique, the low‐temperature plasma (LTP) probe, based on dielectric barrier discharge, is used to detect both minor and trace components (free fatty acids, phenolics and volatiles) in raw untreated olive oil. The method allows the measurement of free fatty acids (the main quality control parameter used to grade olive oil according to quality classes), selected bioactive phenolic compounds, and volatiles. The advantages and limitations of the direct analysis of extremely complex mixtures by the ambient ionization/tandem mass spectrometry combination are discussed and illustrated. The data presage the possible large‐scale application of direct mass spectrometric analysis methods in the characterization of olive oil and other foodstuffs. Copyright © 2009 John Wiley & Sons, Ltd.