Cover – volcanic ash and airspace closures

Trace gases are important components for climate change process, and Earth’s climate is sensitive to change in their atmospheric concentrations; therefore, proper assessment of trace gases is essential for ongoing global climate simulation. The spatio-temporal variations of four trace gases, namely carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), and carbon dioxide (CO₂), over Bangladesh during the last decade are analysed using the remote-sensing data sets of the Atmospheric Infrared Sounder (AIRS) and Ozone Monitoring Instrument (OMI). Monthly, seasonal, and annual mean variations of trace gases were assessed. Higher CO, O₃, and CO₂ concentrations show west-to-east gradient, indicating the impact of both local meteorology and emissions on variations in trace gases. On the other hand, total NO₂ concentration increases over Dhaka because of large population density, high traffic emission, larger industrial activities, and highly polluted air. The inter-annual variations of trace gases are mainly due to large-scale climatic phenomena such as El Niño and La Niña conditions. All the trace gases show strong seasonality, with higher levels during pre-monsoon season and lower levels during monsoon season, which are caused by the seasonal variations in biomass burning (BB), long-range transportation, and rainfall in South and Southeast Asia (S–SE Asia). However, O₃ concentration reveals minimum loading during winter season, associated with the reduction of O₃ formation in cold days due to insufficient heat. These findings are important to estimate regional climate variability due to trace gases.     

浅析F1ash中帧的识别

动画制作已经成为很多人兴趣爱好的必修课。但是利用Flash制作动画时，人们会发现无论是简单动画还是变幻莫测的动画，都会用到帧。然而帧的种类有多种，如何正确区分并掌握它是制作动画的关键。本文先介绍它的分类，然后根据操作时遇见的情况来分析它们之间的区别，并以简单实例来说明。     

F1ash辅助工具让Flash教学充满活力

本文结合笔者多年的Flash教学实践,详细介绍了两类实用的Flash辅助工具:Flash下载工具、Flash反编译工具,这两类工具让Flash教学充满活力!     

F1ash MX组件综合实例

FlashMX中新增了Components UI(UI组件)功能.有了组件的帮助,就可以设计出更复杂、更强大的程序.譬如可以设计一些窗体,用来登记用户的地址、电话、电子邮件地址以及其它个人信息,并在提交到服务器前验证这些数据;或是建立一个多问题、多部分的调查,迅速计算结果并画出调查结果数据图表:或是建立个人像册,存放图像和缩略图;或是创建基于幻灯片的演示文稿的模板.……     

F1ash MX的小技巧两则

掌握Photoshop的一些“隐藏”功能，以助于更快更有效的完成复杂工作，或者它们会告诉你一些你以前所不知道的Photoshop的能力。     

Observations of volcanic ash clouds in the 10-12 μm window using AVHRR/2 data

Abstract

Volcanic aerosols are always present in the atmosphere, but because of the nature of volcanic activity their abundance varies greatly with time. The problem of detecting and monitoring volcanic ash clouds using radiance measurements from the AVHRR/2 (Advanced Very High Resolution Radiometer) instrument is discussed and some results are presented for the Galunggung eruptions of July 1982. It is shown that during the first few hours of an explosive eruption AVHRR/2 thermal channel measurements can be used to detect and discriminate volcanic clouds. Once the eruption cloud has spread and thinned out however, the problem of detection is difficult because of the similarity between dispersed volcanic cloud and semi-transparent cirrus. In these cases, if the volcanic cloud consists of liquid H₂SO₄ droplets, then it is possible to discriminate them from water/ice clouds because of the reverse absorption effect in channel-4 and channel-5. Some evidence is presented showing this effect. It is proposed that the temperature difference image be used operationally to warn of the presence of volcanic clouds.     

F1ash声音对象交互控制的方法比较与实现

本文介绍Flash中使用声音对象实现声音控制的两种方法：attachsound方法和loadsound方法,具体讨论了两者的区别．总结了Flash在动画设计过程中的声音交互控制技术和最优实现方案。     

基于F1ash5．0的多媒体课件开发研究

随着教育事业的飞速发展．社会对计算机辅助教学软件(cay课件）的需求也与日俱增，CAI课件的开发已成为教育界研究的热门课题。在以前的多媒体CAI制作领域．多媒体课件开发主要由VB、Authorware等来完成．基于VB的多媒体课件开发对技术要求较高．在教师中普及有一定的难度．而Authorware在动画的制作上十分薄弱，往往无法满足需要。针对这种情况，我们在比较了多种多媒体创作软件之后，提出使用Flash5．0来制作多媒体课件。     

Eyjafjallajökull volcano ash observed over Belsk (52° N, 21° E), Poland,in April 2010

Eruption of Eyjafjallajökull volcano took place on 13–14 April 2010, and created an ash cloud moving towards densely populated areas in Europe. Dispersion models show that the cloud appeared over Poland at noon on 16 April. Measurements of optical properties of the atmospheric aerosols by the Cimel Sun Photometer (optical thickness and volume size distribution) and lidar (backscatter coefficient) at Belsk (52° N, 21° E) for the period 15–26 April 2010 are examined to find volcanic ash in the atmosphere over the site. Thin aerosol clouds, linked to the volcanic eruption, were found below 5 km, and their optical thickness (at 500 nm) varied only slightly in the range of a few hundredths. The optical depth of the aerosol clouds in the 5–7.5 km layer was less than 0.01.     

Some applications of matrices to location of zeros of polynomials†

In previous papers classical theorems on location of zeros of a polynomial with respect to the left half plane Γ₁ or the unit circle Γ₂ have been reformulated more simply in terms of appropriate companion matrices. It is shown how this work can be extended to the problem of zero location with respect to more general regions Γ of the complex plane. The first approach is to apply the bilinear transformation to the given polynomial, so that for example Γ₁ can be mapped into Γ₂ and a matrix representation of this is derived. An alternative method is discussed which relies on transformation of Γ into Γ₂. Some examples illustrate how any theorem involving Hurwitz-typc minors can be expressed in companion matrix terms, with a consequent halving of the orders of the determinants involved.     

Measurement of the Kernels of a Non-linear System of Finite Order†

A method of measuring the Volterra kernels of a finite-order non-linear system is presented. The kernels are obtained individually as a multi-dimensional impulse response. The multi-dimensional kernel transforms also can be obtained by the method described. As an extension, a technique of obtaining the Volterra kernels from a multi-dimensional step response is presented. This technique is useful for non-linear systems which can be considered to be of a given finite order for only a limited range of input amplitudes.     

The Implementation of Graphic Display of FAS

The principle of the fire alarm system and the implementation techniques of its computer graphic display are presented. With the help of the designing thoughts and technology of OOP, a Fire Alarm System (FAS) has been developed by using visual C++ language. The system has been put into use in many important buildings and has played an important role in monitoring and controlling the fire.     

Visualization of curvature plots and evaluation of fairness: an analysis of the effect of ‘scaling’

Changing the aspect-ratio (scale) of a graphical plot significantly affects the “messages” getting across to a viewer. This is true also for curvature plots and other graphs currently used in Curve & Surface Modeling to evaluate fairness. In particular, the sharp corners appearing in such graphs, employed as local fairness indicators by current practices, are significantly affected by nonuniform scaling. A detailed study of this phenomenon is presented offering specific guidelines for correctly “reading” curvature plots.     

Optimization of linear systems of constrained configuration†

For the sake of simplicity it is often desirable to restrict the number of feedbacks in a controller. In this case the optimal feedbacks depend on the disturbance to which the system is subjected. Using a quadratic error integral as a measure of the response, three criteria of optimization are considered :

1. The response to a given initial disturbance.

2. The worst response to an initial disturbance of given magnitude.

3. The worst comparison with the unconstrained optimal system.

It is shown that for each of these criteria the gradient with respect to the feedbacks can be calculated by a uniform method. The solution may then be found either directly or by a descent procedure. The method is illustrated by an example.     

Stabilization of a class of switched nonlinear systems

The stabilization of a class of switched nonlinear systems is investigated in the paper. The systems concerned are of （generalized） switched Byrnes-Isidori canonical form, which has all switched models in （generalized） Byrnes- Isidori canonical form. First, a stability result of switched systems is obtained. Then it is used to solve the stabilization problem of the switched nonlinear control systems. In addition, necessary and sufficient conditions are obtained for a switched affine nonlinear system to be feedback equivalent to （generalized） switched Byrnes-Isidori canonical systems are presented. Finally, as an application the stability of switched lorenz systems is investigated.     

Contracted product of hypermatrices via STP of matrices

An equivalent definition of hypermatrices is introduced. The matrix expression of hypermatrices is proposed. Using permutation matrices, the conversion between different matrix expressions is revealed. The various kinds of contracted products of hypermatrices are realized by semi-tensor products (STP) of matrices via matrix expressions of hypermatrices.