气象卫星云图压缩编码方法的研究

本文根据对气象卫星云图统计特性的研究结果,提出了一种“差分变换—Huffman编码算法”,并利用该算法对气象卫星云图进行信息保持型压缩编码。文中介绍了在程序中应用本文作者所提出的最小频数顺序合成—逆序分解算法实现这种压缩编码的基本步骤。通过对实际卫星云图磁带数据的压缩编码,结果表明,平均压缩比高达2.4～3.9,最高编码效率达97.9%,并且解码复原图象准确无误。     

Thermodynamic cloud point assays

Analysis of cloud points and clouding curves by varying heating rates using a commercially available automated melting point apparatus is a method to obtain a corrected cloud point for polymers that have a lower critical solution temperature (LCST). Such assays also provide information about the effects of varying heating rates on LCSTs and similar stimuli‐responsive phase separation behavior. This melting point apparatus makes it experimentally simple to conduct such assays that probe the effect of varying heating rates, the effect of polymer structure, and the effect of solution components on the breadth and progress of the phase transition process over a wide temperature range. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 186–193, 2008     

Large eddy simulation of a sheet/cloud cavitation on a NACA0015 hydrofoil

A single fluid model of sheet/cloud cavitation is developed and applied to a NACA0015 hydrofoil. First, a cavity formation model is set up, based on a three-dimensional (3D) non-cavitation model of Navier–Stokes equations with a large eddy simulation (LES) scheme for weakly compressible flows. A fifth-order polynomial curve is adopted to describe the relationship between density coefficient ratio and pressure coefficient when cavitation occurs. The Navier–Stokes equations including cavitation bubble clusters are solved using the finite-volume approach with time-marching scheme, and MacCormack’s explicit-corrector scheme is adopted. Simulations are carried out in a 3D field acting on a hydrofoil NACA0015 at angles of attack 4°, 8° and 20°, with cavitation numbers σ = 1.0, 1.5 and 2.0, Re = 10⁶, and a 360 × 63 × 29 meshing system. We study time-dependent sheet/cloud cavitation structures, caused by the interaction of viscous objects, such as vortices, and cavitation bubbles. At small angles of attack (4°), the sheet cavity is relatively stable just by oscillating in size at the accumulation stage; at 8° it has a tendency to break away from the upper foil section, with the cloud cavitation structure becoming apparent; at 20°, the flow separates fully from the leading edge of the hydrofoil, and the vortex cavitation occurs. Comparisons with other studies, carried out mainly in the context of flow patterns on which prior experiments and simulations were done, demonstrate the power of our model. Overall, it can snapshot the collapse of cloud cavitation, and allow a study of flow patterns and their instabilities, such as “crescent-shaped regions.”     

竖直下抛液体燃料爆炸抛撒的初步数值研究

对具有轴向初始速度即竖直下抛液体燃料的爆炸抛撒云雾形成过程进行了数值研究。近场的数据来自丁珏等的工作,以此数据作为远场初始参数。远场是燃料液滴与空气、燃料蒸汽、不同尺寸的液滴颗粒组成的多相体系之间的相互作用的过程。液滴的直径比较小,把液滴看成连续介质,且相互作用只考虑液滴的蒸发、破碎、碰撞聚合。轴向初速为0(静爆)时计算结果与实验结果相吻合。这说明本模型可以模拟爆炸抛撒云雾的形成过程,进而可以预估高速运动下云雾的形成过程。用以上模型计算了竖直下抛初速为100m/s、装填5kgPO的FAE装置的爆炸抛撒过程。所得的结果表明,100m/s的初速将影响云雾的最终形状及云雾内部的浓度分布。     

Aqueous Photochemistry of 2-Oxocarboxylic Acids: Evidence,Mechanisms, and Atmospheric Impact

Atmospheric organic aerosols play a major role in climate, demanding a better understanding of their formation mechanisms by contributing multiphase chemical reactions with the participation of water. The sunlight driven aqueous photochemistry of small 2-oxocarboxylic acids is a potential major source of organic aerosol, which prompted the investigations into the mechanisms of glyoxylic acid and pyruvic acid photochemistry reviewed here. While 2-oxocarboxylic acids can be contained or directly created in the particles, the majorities of these abundant and available molecules are in the gas phase and must first undergo the surface uptake process to react in, and on the surface, of aqueous particles. Thus, the work also reviews the acid-base reaction that occurs when gaseous pyruvic acid meets the interface of aqueous microdroplets, which is contrasted with the same process for acetic acid. This work classifies relevant information needed to understand the photochemistry of aqueous pyruvic acid and glyoxylic acid and motivates future studies based on reports that use novel strategies and methodologies to advance this field.     

基于Android平台的地震云轮廓提取与匹配研究

针对当前地震云研究中只能利用长期以来的经验进行目视解译,无法形成系统的研究理论和研究模型的现状,结合目前流行的Android便携式设备,提出在Android平台上对地震云图像进行轮廓提取与匹配的研究思路。采用抗噪性能较好的数学形态学算法,在此基础上得到一种改进算法以提取出感兴趣区域,进而通过构造10个新的不变矩对Hu矩匹配算法进行改进,进行轮廓匹配,识别出地震云图像。在Android平台上则利用NDK(Native Delelopment Kit)通过JNI(Java Native Interface)调用OpenCV库函数,用C++语言实现改进算法。实验结果表明:该方法能够有效地识别时间序列下的地震云,正确率高,并且在Android平台上操作简单方便,为地震云预测地震提供初步研究基础和研究依据。     

烟幕初始云团半径变化规律理论模型及实验研究

为了评估烟幕的遮蔽效能,需要对烟幕云团初始参数进行计算,即烟幕云团在爆炸能量下形成的最大半径。本文中基于一种简单烟幕发生装置,把云团的膨胀过程分为2个阶段,分别为等熵膨胀阶段和自由膨胀阶段,建立了烟幕云团膨胀的理论模型,对模型进行分析建立了烟幕云团膨胀过程微分方程组。采用四阶龙格-库塔方法求解得到烟幕云团的半径变化规律。通过实验结果分析可知,该理论模型能够描述给定装置烟幕云团膨胀的基本规律。通过缩比效应,可将其用于爆炸发烟装置初始云团参数的计算。     

移动互联背景下校园卡支付体系设计与实践

针对现有校园卡在脱机和写卡时存在的消费安全隐患,结合互联网技术发展及移动支付应用需求,在分析卡片发展历程的基础上,提出校园卡第3阶段发展概念：即在线化、无卡化、移动化、多介质化;架构适应发展需求的校园卡在线支付体系,建立基于云架构云服务的支付平台和虚拟服务大厅,设计网络、数据、安全和应急响应等保障措施,依托在线账户、二维码、移动终端,实现校园卡支付服务的移动化和自助化.     

基于IIC和云服务器的智能家居控制系统设计

智能家居普遍采用无线通信技术对家居进行互联,不同的通信方法对智能家居系统的稳定性、便捷性、可靠性有很大的影响;针对智能家居的访问方式,通过对比不同的无线通信技术,选择合适的技术运用在智能家居系统的设计中,实现局域网和广域网两种访问方式;在无线传输的智能家居基础上,使用IIC总线进行功能扩展,使用云服务器来替代传统计算机服务器,增加了系统的灵活性和手机访问的快捷性,更好地实现家庭住宅管理与监测,为我们平时的生活提供便利和保护。