A Statistical Study on Photospheric Magnetic Nonpotentiality of Active Regions and Its Relationship with Flares during Solar Cycles 22-23

A statistical study is carried out on the photospheric magnetic nonpotentiality in solar active regions and its relationship with associated flares. We select 2173 photospheric vector magnetograms from 1106 active regions observed by the Solar Magnetic Field Telescope at Huairou Solar Observing Station, National Astronomical Observatories of China, in the period of 1988-2008, which covers most of the 22nd and 23rd solar cycles. We have computed the mean planar magnetic shear angle (\bar{\Delta\phi}), mean shear angle of the vector magnetic field (\bar{\Delta\psi}), mean absolute vertical current density (\bar{|J_{z}|}), mean absolute current helicity density (\bar{|h_{c}|}), absolute twist parameter (|\alpha_{av}|), mean free magnetic energy density (\bar{\rho_{free}}), effective distance of the longitudinal magnetic field (d_{E}), and modified effective distance (d_{Em}) of each photospheric vector magnetogram. Parameters \bar{|h_{c}|}, \bar{\rho_{free}}, and d_{Em} show higher correlation with the evolution of the solar cycle. The Pearson linear correlation coefficients between these three parameters and the yearly mean sunspot number are all larger than 0.59. Parameters \bar{\Delta\phi}, \bar{\Delta\psi}, \bar{|J_{z}|}, |\alpha_{av}|, and d_{E} show only weak correlations with the solar cycle, though the nonpotentiality and the complexity of active regions are greater in the activity maximum periods than in the minimum periods. All of the eight parameters show positive correlations with the flare productivity of active regions, and the combination of different nonpotentiality parameters may be effective in predicting the flaring probability of active regions.Comment: 20 pages, 5 figures, 4 tables, accepted for publication in Solar Physic

Comparison of endosperm amyloplast development and degradation in waxy and non-waxy wheat

The waxy wheat shows special starch quality due to high amylopectin content. However, little information is available concerning the development and degradation of amyloplast from waxy wheat endosperm. To address this problem, waxy wheat variety, Yangnuo 1, and a non-waxy wheat variety, Yangmai 13, were chosen to investigate the development and degradation of endosperm amyloplast during wheat caryopsis development and germination stage respectively using histochemical staining and light microscopy. Changes of morphology, the soluble sugar and total starch content were indistinguishable in the process of caryopsis development of two wheat varieties. The developing endosperm of non-waxy was stained blue-black by I2-KI while the endosperm of waxy wheat was stained reddish-brown, but the pericarp of waxy and non-waxy wheat was stained blue-black. In contrast to nonwaxy wheat, endosperm amyloplast of waxy wheat had better development status and higher proportion of small amyloplast. During seed germination many small dissolution pores appeared on the surface of endosperm amyloplast and the pores became bigger and deeper until amyloplast disintegrated. The rate of degradation of waxy wheat endosperm amyloplast was faster than non-waxy wheat. Our results may also be helpful to the use of waxy starch in food and nonfood industry

An experimental study of spray cooling of a flip chip

10.1109/EPTC.2007.4469844Proceedings of the Electronic Packaging Technology Conference, EPTC167-17

Corrosion protection of 316 L stainless steel by a TiO2 nanoparticle coating prepared by sol-gel method

A uniform and TiO2 nanoparticle coating on steels has been prepared using sol-gel method and hydrothermal post-treatments. The morphology and structure of the coatings were analysed using atomic force microscopy and X-ray diffraction. The anticorrosion performances of the coatings in dark and under ultraviolet illumination have been evaluated by using electrochemical techniques. The influences of coating thickness, pH and NaCl concentration on corrosion protection have been examined as well. The results indicate that the TiO2 nanoparticle coatings on steels exhibit an excellent corrosion resistance due to a ceramic protective barrier on metal surface in dark, and a photo-generated cathodic protection current under UV illumination. The electrochemical impedance spectroscopy measurements provide an explanation to the increased resistance of nano TiO2 particles coated 316 L stainless steel against corTosion. (c) 2005 Elsevier B.V. All rights reserved

Aerodynamic Characteristics of Individual Ballast Particle by Wind Tunnel Tests

Ballast flying has been considered as a problem in train aerodynamics with increasing the maximal speed. And this phenomenon seriously threats the safety of train operation. However, aerodynamic characteristics of individual ballast were less studied in the previous literature. This paper describes an investigation of the aerodynamic effect of ballast particles by wind tunnel tests. It considers the nature of the wind and ballast physical characteristics. A simple method for calculating the wind effects by CFD is set out, ballast particles were classified according to their shapes and mass in order to investigate the influence of the wind velocity, wind pressure and other parameters on displacement of ballast particles. Two sets of wind tunnel tests were performed under the conditions that ballast particles were movable and unmovable on the platform respectively. The tests data and reasonable explanations were given, as well as the CFD simulations of individual ballast particles

Study on a hydrophobic nano-TiO2 coating and its properties for corrosion protection of metals

A uniform TiO2 nanoparticle film has been coated on the surface of 316L stainless steel by using sol-gel and dip-coating technology. A hydrothermal post-treatment method has been developed to eliminate the crack defects in the coatings, and to improve the structure and property for the coating. A self-assembly of fluoroalkylsiane (FAS-13) has been conducted to enhance the surface hydrophobic property of the nano-TiO2 coatings. The distribution of particle sizes of TiO2 sol has been analyzed by zeta-potential analysis, and the surface morphology and structure have been characterized by contract angle, XRD, and SEM measurements. The results indicate that the surface of coatings is uniform and dense, with approximately 375 nm thickness. The diameter of particles of TiO2 anatase is in the range of 15-18 nm. The contact angle of the super-hydrophobic surface is 150 +/- 1 degrees. It shows, from the electrochemical tests, that the super-hydrophobic coatings on 316L stainless steel exhibit an excellent corrosion resistance in chloride containing solution at the room temperature. (C) 2005 Elsevier Ltd. All rights reserved

Ultrafast-laser-induced parallel phase-change nanolithography

10.1063/1.2235855Applied Physics Letters894-APPL

Hybrid laser micro/nanofabrication of phase change materials with combination of chemical processing

10.1016/j.jmatprotec.2007.04.089Journal of Materials Processing Technology192-193340-345JMPT