基于数据同化的图像融合方法研究

数据同化凭借其在数值预报中将观测数据与理论模型相结合的特点,目前广泛应用于遥感图像处理及图像融合领域。文中介绍了数据同化的含义和数据同化系统的构成,并分析了其应用于图像融合的原理;结合现有的研究成果着重分析了数据同化框架下结合不同优化算法的图像融合方法,并对其进行分类比较,给出了各方法的优缺点和研究成果及应用;最后在总结了各种基于数据同化的图像融合方法普遍存在的问题的基础上,探讨了进一步发展与研究的方向。     

浅谈计算机信息保密安全技术

伴随着新媒体广播电视行业信息化建设的加快,对计算机的使用也越来越广泛,基于网络连接的计算机信息安全问题也日益突出,信息安全保密显得尤为重要.针对计算机信息的安全威胁,怎样才能确保信息的安全性,本文通过阐述信息安全保密的概念、分析信息安全的现状及威胁因素,最终提出信息保密安全技术的具体方法.     

基于ASP的电子商务网站中购物车设计与实现

该文介绍了一种基于ASP技术的电子商务网站中购物车模块的设计与实现。在设计中分析了购物车的数据流程,重点对购物车容器模块和添加商品功能模块进行了设计和实现。为电子商务网站开发进行了一个有益的探索。     

Multifunctional π-conjugated poly (3-methylthiophene) nanotubes for optoelectronic and field emissive devices

Multifunctional properties of nanomaterials becomes a hot topic in nano research for the development of multifunctional devices, because modern devices need multifunctional platform for the high efficient plural performance on a single device. Here, we introduce a multifunctional π-conjugated poly (3-methylthiophene) (P3MT) nanotube (NT), showing controllable optical and electrical properties through the control of doping level. P3MT NTs were electrochemically synthesized in the low temperature (−40 °C) on the nanoporous template. The change of doping level by post cyclic voltammetry (CV) treatment on the P3MT lead the variance of polaron/bipolaron band, resulting into the drastic change of ultraviolet-visible absorption and photoluminescence properties. While P3MT NTs before CV treatment show an ohmic behavior in the current-voltage characteristics, those after CV treatment show high photocurrent. From the field emission experiment, the P3MT NTs before CV treatment have a relatively low turn-on electric field and stable electron emission property compared to the P3MT NTs after CV treatment. This shows that the π-conjugated polymers should be shed new light on their multifunctionality for the potential application to the multifunctional platform of opto-electronic nanodevices.     

SQM-OTFT: A compact model of organic thin-film transistors based on the symmetric quadrature of the accumulation charge considering both deep and tail states

A physically-based compact model of organic thin-film transistors suitable for CAD simulators is proposed. It is worked out by means of a newly developed and particularly simple form of the charge-sheet model: the symmetric quadrature of the accumulation charge. The model is based on the variable-range hopping and accounts for both deep and tail states. It is simple, symmetric, accurately accounts for the below-threshold, linear, and saturation regimes via a unique formulation. The symmetric quadrature is accurate within 5% in all regions of operation and the resulting current model is suitable both for p- and n-type transistors. The model leads to a significant simplification of the drain current and of the quasi-static expressions of the terminal charges based on the Ward–Dutton partition. Finally, the symmetric quadrature leads to an explicit and analytically tractable solution for the surface potential as a function of position in the device channel that can be extremely useful to implement advanced physical effects.     

低功耗、高可靠性PC/104总线控制器设计

通过对PC/104总线协议的分析,提出相应总线控制器的设计方法.基于面向航空领域应用所具备的特殊要求以及SoC系统的特点,对设计的可靠性及功耗方面做出改进,包括对关键信号的去噪音处理;为从已陷入长等待的状态恢复至正常模式而加入的延时等待逻辑;门控时钟被采用以作为正常工作模式与睡眠工作模式的切换;对主要功耗部分状态机进行优化编码.使用FPGA测试结果表明,该PC/104总线控制器设计安全可靠,功耗低,可以很好地支持大部分PC/104总线设备.     

2.5 GHz城市环境电磁态势的计算与补偿

复杂城市空间的电磁态势分布可以通过电磁场数值计算的方法进行预测。文章使用矩量法(MOM)结合一致性几何绕射理论(UTD)的方法对2.5 GHz频率下某小区环境中的电磁态势进行了仿真计算以及实际测量。场景中的树木结构在此频率下显示出比较强烈的波动性,对电磁仿真计算结果产生了不可忽略的影响,文中将其对仿真计算结果的影响进行了单独建模仿真,给出其产生影响的经验值,对仿真结果进行修正。修正结果与测量结果对比证明该经验值在该频率下可以有效补偿计算结果的缺失。     

High-temperature fatigue behavior of SiC-coated carbon/carbon composites in oxidizing atmosphere

Tensile fatigue-stressed oxidation experiments were conducted at 1300 °C in oxidizing atmosphere to identify the failure modes and degradation mechanism of a SiC-coated carbon/carbon composite. Five peak fatigue stresses were selected between 90 and 150 MPa and the results showed that the higher the applied stress, the shorter the composite life. Electrical resistance of the composite was acquired in real-time. The composite resistance appeared a slight drop in the initial fatigue period and followed by a continuous increase until failure. Both the changes in modulus and resistance revealed the shrinking core mechanism in the fatigue-stressed oxidation experiments. A model was developed based on a half-cylinder oxidation pattern. Simulations were conducted on the basis of this model, and the results agreed with the experimental data fairly well.     

Improving lifetime of phosphorescent organic light-emitting diodes by using a non-conjugated hybrid host

Three hybrid host materials, mCP-PhSiPh3, mCP-L-PhSiPh3, and tBu-mCP-L-PhSiPh3, have been synthesized and characterized for their thermal, morphological, electrochemical, fluorescence, phosphorescence, and electroluminescence properties. The flexible spacer in mCP-L-PhSiPh3 and tBu-mCP-L-PhSiPh3 makes them maintain high triplet energies at about 3.00 eV due to the interruption of π-conjugation. The introduction of the tert-butyl group at the electrochemically active C3 and C6 sites of the carbazole moiety greatly improves thermal and electrochemical stability of the host tBu-mCP-L-PhSiPh3. Blue and green phosphorescent organic light-emitting diodes (PhOLEDs) based on the non-conjugated hosts exhibit external quantum efficiencies at around 15 and 21%, respectively. Higher current densities in PhOLEDs hosted by mCP-PhSiPh3 produce current leakage, resulting in lower efficiencies, especially in green PhOLEDs. The green PhOLEDs using non-conjugated hosts show improved device lifetime in comparison with the mCP-PhSiPh3 based PhOLED because of enhanced morphological stability. The operational stability of the tBu-mCP-L-PhSiPh3 based device is further raised because of improved electrochemical stability by employing the tert-butyl group. Our results demonstrate that both the flexible linkage and the blocking of the electrochemically active sites are crucial measures to realize long-lived PhOLED devices.     

基于嵌入式Linux与S3C2410平台的视频采集

针对数字网络视频监控系统的需求,设计一种基于MPEG-4网络视频服务器。使用基于MPG440的MPEG-4实时视频压缩卡压缩采集到的音视频数据,利用循环队列实现音视频数据的压缩,同时运用多线程技术以及传输机制解决网络数据的传输,从而有效克制了画面不清晰、音视频不同步、马赛克等现象,保证客户监看时音视频实时性和同步性。经过实验证明,该方案经济高效,可应用在多种需要音视频监控的场合。