HTTP邮件网关设计和实现

本文首先介绍了HTTP邮件系统的基本原理和关键技术，然后针对其不提供POP3网关的问题．提出并实现了一种HTTP邮件网关。该网关实现了SMTP／POP3协议到HTTP协议的相互转换，使普通邮件客户程序也能方便快捷地在本地硬盘上收发HTTP邮件。     

基于SMTP邮件系统的邮件寻呼的实现

介绍了基于常见的SMTP邮件系统的邮件寻呼实现，是传统的电信寻呼业和现有的计算机网络技术的良好结合。系统在客户端实现了POP3协议，另外本文还给出先进的MD5数字签名算法的流程。     

问答信箱

1． 什么是POP3﹖答： POP 即为 Post Office Protocol 的简称,是一种电子邮件传输协议,POP3 是它的第三个版本,是规定怎样将个人计算机连接到 Internet 的邮件服务器和下载电子邮件的电子协议。它是 Internet 电子邮件的第一个离线协议标准。简单说,POP3 就是一个简单而实用的邮件信息传输协议。2． 什么是 SMTP﹖ 答： SMTP的全称是“Simple Mail Transfer Proto－col”,即简单邮件传输协议。它是一组用于从源地址到目的地址传输邮件的规范,通过它来控制邮件的中转方式。SMTP 协议属于 TCP ／ IP 协议簇,它帮助每…     

内部E-mail通向Internet的捷径——MDaemon

MDaemon是Windows 9x／NT／2000下的SMTP／POP3／IVAP4邮件系统,它特别适用于那些既需要在局域网中互相发送电子邮件,也需要在Internet上互发邮件的用户。即使在没有专线、路由器、网关等这些昂贵设备的情况下,我们依然可以利用MDaemon在局域网和Internet网上互发邮件。     

一种基于SPKM的挂号保密电子邮件

引言 在金融、行政、办公等领域,往往需要对邮件的内容进行保密,邮件接收方需要确认邮件的有效性,邮件发送方需要得到接收方的“收据”来确知邮件被正确的接收方接收并实现责任分开,以对此后可能产生的纠纷提供证据。目前电子邮件客户端与邮件服务器交互使用的是SMTP协议(简单邮件传输协议)与POP3协议(邮局协议),这两项协议并没有提供安全技术来保证上述要求。而且由于SMTP协议与POP3协议实行的是网络明文传输,不但邮件内容暴露于网上,连用户的帐号信息也不能幸免,为用户埋下了巨大的安全隐患。     

长途电话账单再也不会来了

众所周知，IP电话的实现方式有3种，即PC到PC，PC到电话，电话到电话。其中最具商用性的是电话到电话方式。目前中国电信、联通和吉通在国内推出的IP电话业务就属此类，它的实现需要通过营运商的同关，由于现在正处于实验阶段，网关的容量有限，所以用户不多，这不免使许多希望享受廉价长途电话服务的而家里又没有电脑的用户感到失望。不过下面介绍的一种称之为IPStar的装置（在上海地区有销售）也许能弥补这些用户的遗憾。IPStar实质上是一个可自行设置的小型网关，它内附一个cpu和33．6kModem，具备语音压缩功能，无需电脑或其他周…     

新一代电子邮件系统的推广应用

新一代电子邮件系统采用分布式结构,除了提供传统的SMTP／POP3／IMAP4服务外,还增加了独具特色的Web Mail、基于Web的系统管理、多媒体电子邮件处理、邮件短信服务等功能。系统具有大用户量并发处理的能力,并能让用户享受到许多个性化服务。     

基于语音邮件的家校通服务系统的设计与实现

设计和实现了基于语音邮件的家校通服务系统。通过语音邮件网关可以实现只用普通电话就可以收发语音邮件,根据具体应用的要求对UDP协议进行了必要的改进,弥补了UDP协议在可靠性和流量控制等方面存在的不足;并使用组件化编程技术对IMAP4、SMTP邮件协议和语音格式转换模块进行封装,减轻了编程的工作量、提高了代码的可重用性。系统投入运行之后的效果表明:语音处理流畅、系统性能较好。     

一种基于邮件协议的僵尸网络的设计与实现

本文首先简要介绍了基于IRC协议的僵尸网络的工作原理,而后在分析SMTP/POP3协议的基础上提出了一种基于邮件协议的僵尸网络,接着阐述了该新型僵尸网络的基本原理和优点,最后以接收邮件为例实现了该僵尸网络的建立过程。     

基于4 Kb/s DP-CELP声码器的高容量语音邮件系统设计

针对市场上国内外语音邮件产品压缩率不高、录音方式不够灵活等问题。提出一种基于4Kb／s DP-CELP语音编码方案以及录播实时、存储高效、录音灵活的语音邮件系统设计方案。系统在Borland的C＋＋Builder6．0集成开发环境下使用Windows底层音频API函数开发，采用双缓冲技术保证实时录播。仿真结果表明，回放话音质量优良，系统稳定可靠，具有潜在的实用价值。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.