基于嵌入式的安防系统的前置终端设计

将嵌入式技术和射频识别技术相结合应用于安防系统前置终端是嵌入式系统在安全防护领域中的一种新应用.论述了安防系统前置终端的软、硬件设计与实现.硬件设计论述了各个硬件模块的设计思路,功能和电路原理.系统软件也遵循模块化的设计方法,以对应硬件电路的各个模块.文中从嵌入式系统的软、硬件设计以及应用出发,较全面地论述了嵌入式系统,掌握了嵌入式系统开发的核心技术,并为更复杂的嵌入式系统的开发和应用奠定了坚实的基础.     

嵌入式系统的低功耗设计技术

随着嵌入式系统的广泛应用,低功耗问题摆在了设计人员面前.低功耗设计包括系统设计、硬件设计、软件设计、器件的工艺设计等诸多方面.其中器件的工艺设计主要由半导体器件的厂家来完成,嵌入式系统的应用设计人员只需要关心器件的功耗指标,更多的工作集中于系统的硬件、软件以及它们之间的配合方面.本文主要从这些方面讨论嵌入式系统的低功耗设计问题和设计方法.     

计算机嵌入式系统的设计技术

计算机领域中,嵌入式系统的出现是计算机软硬件和功能模块化的具体体现,是面向应用设计的软硬件可裁剪的计算机系统,能够满足不同行业、环境等的特殊要求.随着计算机技术的发展和深度应用,嵌入式系统的优势得到体现,发展极为迅速,对人们的日常活动产生极为深刻的影响.为了把握计算机嵌入式系统的基本特征、设计流程,分析其存在的发展阻碍和发展趋势,本文对计算机嵌入式系统的设计技术做详细阐述.     

基于嵌入式处理器的系统级低功耗管理研究

针对嵌入式系统低功耗设计问题,分析了动态功率管理DPM和动态电压/频率调节DVFS两种嵌入式功耗管理策略,并提出了系统级低功耗控制框架.讨论了基于嵌入式处理器i.MX1硬件平台实现系统级功耗控制方案,并给出了具体的设计方法.实际应用表明,该设计方案可有效降低系统能耗.     

基于AVR高性能单片机的以太网接口设计

随着Internet的发展和应用,嵌入式系统在网络方面的应用技术也逐渐成熟.针对目前大量使用8住微控制器的嵌入式系统,采用ATMEL公司的高性能单片机ATmega64和10 Mb/s以太网控制芯片RTL8019AS,设计了低成本的嵌入式以太网接口,详细介绍了硬件电路的连接以及嵌入式TCP/IP的实现,远端用户可以通过HTTP协议来访问存储在嵌入式系统上的网页,使嵌入式系统具备网络连接功能.     

用于嵌入式计算机性能评测技术及其方法研究

嵌入式系统及应用与市场密切关联,其设计受成本、功耗、芯片体积和开发周期等多种因素的制约,嵌入式系统的性能在满足应用需求的条件下,其性能冗余量不宜太大。在产品开发周期内,以尽可能低的原材料成本和开发成本设计具有适当性能的嵌入式系统,是嵌入式系统项目成功的关键。为此,需要对嵌入式微处理器及嵌入式系统的整体性能进行评测和分析,作为嵌入式系统性能设计的依据。介绍嵌入式系统性能测试的基本原理、测试方法,描述多种嵌入式系统性能评测基准及其适用范围。并在此基础上,分析这些嵌入评测基准程序的应用情况,结合当前嵌入式系统级设计过程中需要早期进行性能评估的需要,介绍E3S评测基准及系统级设计评价方法,给出嵌入式计算机设计中测评技术的未来发展趋势。     

基于ARM的以太网接口电路设计

阐述了基于ARM处理器LPC2294的嵌入式系统的以太网接口电路的设计,针对当前嵌入式研究领域的技术热点,实现了以太网功能在嵌入式系统上的开发与应用.详细介绍了ARM处理器的硬件设计,LPC2294与以太网控制器RTL8019AS的接口电路设计和以太网传输层的UDP协议、TCP/IP协议的软件设计流程,以及系统的通信调试过程.ARM处理器与RTL8019AS通过外部数据总线连接,具有非常好的实时性和可靠性,很好地实现了嵌入式系统的以太网功能.     

单芯片嵌人式网关在煤矿井下人员定位中的应用

设计并实现了单芯片嵌入式网关(TCP/IP转RS 485)以及在煤矿井下人员定位中的应用.在嵌入式以太网的网关构架下设计了嵌入式硬件和软件,并在实际应用中证明该系统具有成本低、集成度高、速率快以及开发周期短等特点.首次将单芯片以太网引入煤矿井下光纤环网,并设计了简化、实用、高效率的服务器/客服端应用程序.     

嵌入式Linux系统的开发与优化

介绍了嵌入式系统的概念和Linux系统的嵌入式特性,分析了嵌入式Linux系统的开发流程、工具链、内核移植和文件系统的设计,并从系统启动、体积和内存占有率等方面着手,讨论了嵌入式Linux系统的优化方案。该设计在国家体育总局的嵌入式计时产品中得到应用,提高了系统的稳定性、响应速度和运行效率。     

基于ARM9的嵌入式系统研究及设计

为适应嵌入式技术在现代工业及电子等更多领域的广泛应用,通过对ARM9嵌入式微处理器芯片S3C2410的研究,设计出基于S3C2410核心板的嵌入式系统开发底板,更多的需求及功能可在其底板上进行扩展与实现.首先对ARM9嵌入式微处理器S3C2410进行介绍,然后给出了基于S3C2410核心板的嵌入式系统开发底板的设计与功能扩展,包括开发板总体设计,电源模块设计,各种通信模块设计如串口、JTAG接口、网络接口、CAN总线通信接口等.该模板的设计实现了嵌入式系统在更多更广泛领域应用的灵活性.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-