多媒体通信的关键技术及应用

本文主要讨论多媒体通信技术及其应用。文中介绍了多媒体通信的概念及特征,分析了多媒体通信中的一些关键技术,包括压缩编码、同步技术、终端技术、多媒体数据库。概述了多媒体通信的应用。     

多媒体通信网中的安全技术

多媒体通信技术近年来发展迅速,多媒体通信业务层出不穷,全球信息数字化的通信新业务将朝着多媒体方向发展,特别是宽带通信业务将全部是多媒体业务,需要人们了解更多的多媒体通信性能,掌握多媒体通信的基本知识和安全技术特点。     

浅谈基于多媒体通信网中的安全技术

多媒体通信技术近年来发展迅速,多媒体通信业务层出不穷,全球信息数字化的通信新业务将朝着多媒体方向发展,特别是宽带通信业务将全部是多媒体业务,需要人们了解更多的多媒体通信性能,掌握多媒体通信的基本知识和安全技术特点。     

探讨多媒体通信技术在远程教学中的应用

在远程教学过程中多媒体通信起到关键作用的技术,本文研究基于网络技术的远程学习模式,对利用多媒体通信的数据对象进行详细的分析,并将多媒体通信系统的开发应用在远程教学里,研究多媒体通信功能对远程学习支持的功能,充分利用网络资源实现远程教学。     

多媒体通信终端技术

文章从多媒体通信终端的硬件结构、软件结构及性能上阐述了多媒体通信终端技术及多媒体通信终端的发展趋势。     

多媒体通信关键技术及应用

多媒体通信的广泛应用极大地提高了人们的工作效率,改变了人们的生活方式.本文简要介绍了多媒体通信的概念和特征、多媒体通信的主要关键技术以及应用.     

多媒体通信技术的应用及发展

就多媒体通信技术目前的应用作了阐述,并对多媒体通信技术的发展进行了较深刻的论述;最后简要说明了多媒体通信技术所遵循的国际标准及其用途。     

IPv6对多媒体通信的支持

本文分析了网络传输协议Ipv6,讨论了Ipv6在多媒体通信中的优势及Ipv6支持多媒体通信的技术措施和Ipv6在多媒体通信中的实际应用。     

多媒体通信技术

本文在介绍了多媒体通信基本特征的基础上，着重讲述了多媒体通信的关键技术和多媒体通信的控制协议。     

基于SIP的多媒体通信网络构建

在多媒体网络上流动着数字数据、语音数据和视频数据,从而形成一个融合了语音、视频与数据三者的计算机多媒体通信网络。多媒体通信网络是许多网络专业工作者关心的技术,基于SIP的多媒体通信网络又是时下最流行组网方式。因此,就多媒体通信网络构建提出一些设计思路。     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.     

HUYGENS' PRINCIPLE,PHYSICS AND COMPUTERS

We discuss the emergence of topology from a consideration of set extensions in General Systems Theory. Boundaries arise in a natural way, separating independent elements or regions of the system. Our aim is a unification of Etter theory, Kron's method of Tearing and Jessel's formulation of Huygens' Principle. This should make explicit the equivalence between the objective, structural, holographic and the subjective, relative definitions of information, sought in Bowden (1994b), reprinted in this Special Issue. It connects the abstract generalisations of Schrodinger's equation and Bom's rule derived in probabilistic Etter theory with the real world of electrical and other physical phenomena in General Physical Systems Theory. This paper can be considered as a continuation of Bowden (1990; 1994a) and as a response to Bowden (1994b), reprinted in this issue.

We review the ideas behind Kron's Method of Tearing and Jessel's Principle of Secondary sources (both special cases of the above theory) and their equivalence. We follow Hiley's argument in Hiley (1996) to show how Schrodinger's equation can be thought of as specifying the evolution of (a series of) tearings in continuous space. These can be shown on a commutative diagram as a series of similarity transforms. We compare this with Etter's derivation (Etter, 1998). We describe briefly a recently published derivation of Maxwell's equations from a non-commutative algebra and show how they fit onto a related commutative diagram. Finally we make some comments on applications of the general theory to computer systems. This paper is a series of vignettes of work in progress. It is designed to point the direction of work to come in Constructive Physics.     

Innovative uses of ICT in Chilean schools

Abstract This paper presents some of the results of the study of seven cases of innovative pedagogical practices using ICT. The study was performed in the framework of the application of SITES M2 in Chile. The results are divided in two sections. First is a summary of each case, highlighting its innovative characteristics that serve as models of 'good practice' for Chilean teachers. Second, the results of the analysis of what teachers did are outlined; the impact on students and the type of teaching and learning activities in use. Results show that these projects did not provide evidence of having impact on students' learning as defined in the national curriculum. However, they show that students participating in these projects could learn other things, had the opportunity to develop abilities defined as cross-curricular and practised ICT related skills. The analysis of the teaching and learning activities highlights some deficiencies in the way that teachers implement new teaching strategies.     

Forage quality of savannas — Simultaneously mapping foliar protein and polyphenols for trees and grass using hyperspectral imagery

Savanna covers about two-thirds of Africa, with forage quantity and quality being important factors determining the distribution and density of wildlife and domestic stock. Testing hypotheses about the distribution of herbivores is hampered by the absence of reliable methods for measuring the variability of vegetation quality (e.g. biochemical composition) across the landscape. It is demonstrated that hyperspectral remote sensing fills this gap by revealing simultaneously the spatial variation of foliar nitrogen (crude protein) as well as the total amount of polyphenols, in grasses and trees. For the first time, the pattern of resources important for feeding preferences in herbivores (polyphenols and nitrogen) is mapped across an extensive landscape and the modeled foliar concentrations are shown to fit with ecological knowledge of the area. We explain how estimates of nitrogen (crude protein) and polyphenols may be scaled up from point-based observations to reveal their spatial pattern, and how the variation in forage quality can influence the management of savannas, including farms, communal grazing areas, and conservation areas. It provides a glimpse of the choices herbivores must face in selecting food resources of different qualities.     

Remote sensing of spring phenology in boreal regions: A free of snow-effect method using NOAA-AVHRR and SPOT-VGT data (1982-2004)

Measurements of spring phenological dates in boreal regions using NDVI can be affected by snowmelt. This impacts the analysis of interannual variations in phenology and the estimates of annual carbon fluxes. For these two objectives, snowmelt effect must be removed from the phenological detection. We propose a methodology for determining the date of onset of greening in the 1982-2004 period using SPOT-VEGETATION (VGT) and NOAA Advanced Very High Resolution Radiometer (AVHRR) data. From 1998 onwards, the date of onset of greening is taken as the date at which the Normalized Difference Water Index (NDWI), calculated from SPOT-VGT near and short-wave infrared bands, starts increasing. This index decreases with snowmelt but increases with vegetation greening. For the 1982-2001 period, the date of onset of greening is the date at which AVHRR-NDVI equals a pixel specific threshold (PST), determined using the results of the NDWI method in the years common to the two datasets. The methods are validated using in situ measurements of the dates of leaf appearance. RMSE of 6.7 and 7.8 days, respectively, is found using NDWI-VGT and PST-NOAA methodologies, and the difference between the two methodologies in the common years is small. Very importantly, the dates are not biased. The interannual variations of the 23-year spring phenology dataset on the study area in northern Eurasia are analysed. In average over the study area, an advance of 8 days and a delay of 3.6 days are, respectively, found over the periods 1982-1991 and 1993-2004. These results confirm and complete previous studies about the greening trend, remove the uncertainty due to snow, and may improve carbon budget calculations.     

Real-world effectiveness of Ergonomic methods

The way ahead with the practical development and application of Ergonomic methods is through a better anticipation and appreciation of changes to system effectiveness and human work that will be incurred through the introduction of new technologies to the workplace. These improvements will involve an improved awareness by the system of the working context and environment. The argued future is with improvements in the handling and use of knowledge by systems. The development of suitable Ergonomics methods, or the careful adaptation of existing methods, should accompany any technological revolution. Moreover, future methods are needed that are specifically developed to be applicable to the real time study of work considering both work context and the amalgamation of results from the use of many diverse methods throughout the design and development life cycle of a system. Part of this process will be a necessary complementation of both quantitative and qualitative methods and guidelines. Another focus should be on creating improved Ergonomics participation within multidisciplinary system design and development environments throughout the system's life cycle. Only through this avenue can Ergonomics show a consistent and valued contribution to quality design and its development. In parallel to such a contribution will be an acceptance by other engineering disciplines, managers, and customers that such an application of Ergonomics is cost effective.     

基于Android 平台的工程图学助教助学系统研究与实现

针对空间想象能力培养的教学需要,对基于Android 平台的工程图学助教助学系统 进行了研究。根据教与学的需要,确定了系统功能,设计了软件的框架结构。分析研究了移动设 备的系统平台,选择了系统的开发及运行平台。通过分析Android 框架中OpenGL ES 的设计接口, 实现了模型的轴测显示模式。通过分析OpenGL ES 中glDrawElements 方法的数据需求和VRML97 的数据格式,设计了虚拟模型加载器,实现了Android 系统中的VRML 模型3D 浏览器。开发了 软件的核心功能模块,设计实现了基于Android 平台的工程图学助教助学系统。该系统因其创新 性和实用性,在2014 年第十四届全国多媒体课件大赛中荣获一等奖。     

3 Laser transmission joining in microtechnology

The laser is a joining tool which is particularly suitable for the application in microtechnology. The process variant laser transmission joining can be used both for welding thermoplastics and bonding of silicon and glass. The investigations presented in this paper cover detailed examinations of both processes. Concerning laser transmission welding of plastics it is examined how far the content of carbon black in the material influences the formation of the weld seam. It is shown that the optical depth of penetration, the weld seam width as well as the formation of the weld morphology differ with varying content of carbon black. Selective laser radiation bonding (SLB) is a novel method for joining silicon and glass based on the transmission heating of the interface of both joining partners and the thermo-chemical principles of silicon direct bonding. SLB shows advantages in reference to the thermal load of sensitive components like sensors and to the selectivity of the joining geometry. In this study the principle method of SLB and the latest advances like the integration of the thermal process control in the laser processing head will be presented. Also experimental test results of the process with constant laser power and thermal process control and the comparison of them will be shown.An erratum to this article can be found at     

An approach to the synthesis of fuzzy stabilization systems with a priori unknown model of an object

A method of synthesis of fuzzy stabilization systems for a broad class of dynamic objects under the assumption that the mathematical model of the object is not known a priori is proposed. The control is formulated in the form of a proportional law of adjustment as a function of a macro-variable; the square of the Euclidean norm of the phase variables is adopted as the macro-variable. An analogous variable characterizes the distance of the object from the equilibrium position. Despite the simplicity of the control law, its sign remains constant due to the fact that the macro-variable is positive-definite over the entire phase space. The switching times of the signals are determined by fuzzy identification of the system’s dynamic modes on the basis of measurement of the derivatives of the macro-variable.