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红外动态图像生成技术概念研究 总被引:4,自引:0,他引:4
红外动态图像生成技术的基本概念包括基本术语及其定义。为了描述红外动态图像生成技术的特性,通常采用如光源类型、光谱波段、阵列规模、空间分辨率、填充因子、时间常数、帧频、闪烁、温度范围、串扰、均匀性、发射率、辐射对比度、动态范围、温度分辨率、调制传递函数、几何畸变及最大温度和最大辐射强度等概念。介绍了描述红外动态图像生成系统性能的基本概念的定义。转换器的指标定义对于转换器的设计和性能指标的测试都有重要的意义。 相似文献
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热释电系数的测量方法 总被引:2,自引:0,他引:2
描述热释电系数的两种测量方法。其一为电荷积分法,测试系统简单,测量数据准确,且能满足零电场条件下的测量。其二为动态电流法,采用调制热源技术,研究在特定温度条件下热释电材料的动态热释电响应。 相似文献
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Xiao Huang Bishwa Ranjan Nayak Tao Lu Lowe 《Journal of polymer science. Part A, Polymer chemistry》2004,42(20):5054-5066
A series of novel multifunctional hydrogels that combined the merits of both thermoresponsive and biodegradable polymeric materials were designed, synthesized, and characterized. The hydrogels were copolymeric networks composed of N‐isopropylacrylamide (NIPAAM) as a thermoresponsive component, poly(L‐lactic acid) (PLLA) as a hydrolytically degradable and hydrophobic component, and dextran as an enzymatically degradable and hydrophilic component. The chemical structures of the hydrogels were characterized by an attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR) technique. The hydrogels were thermoresponsive, showing a lower critical solution temperature (LCST) at approximately 32 °C, and their swelling properties strongly depended on temperature changes, the balance of the hydrophilic/hydrophobic components, and the degradation of the PLLA component. The degradation of the hydrogels caused by hydrolytic cleavage of ester bonds in the PLLA component was faster at 25 °C below the LCST than at 37 °C above the LCST, determined by the ATR–FTIR technique. Due to their multifunctional properties, the designed hydrogels show great potential for biomedical applications, including drug delivery and tissue engineering. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5054–5066, 2004 相似文献
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Liljana Gavrilovska 《Wireless Personal Communications》2006,37(3-4):271-290
Wireless ad hoc networks are temporary formed, infrastructureless networks. Due to the unstable channel conditions and network connectivity, their characteristics impose serious challenges in front of network designers. The layering approach to network design does not fit the ad hoc environment well. Therefore, various cross-layering approaches, where protocol layers actively interact, exchange inherent layer information and fine tune their parameters according to the network status are becoming increasingly popular. This paper presents an in-depth analysis of the latest cross-layering approaches for wireless ad hoc networks supported by several examples. A special emphasis is put on the link and network layer related cross-layer designs. Several link adaptation and efficient service discovery schemes are elaborated through analytical and simulation studies. Their performance shows the potentials of the cross-layering for boosting system characteristics in wireless ad hoc networks.
Liljana Gavrilovska currently holds a position of full professor at Faculty of Electrical Engineering, University “St. Cyril and Metodij” – Skopje, Macedonia. She is chief of Telecommunications Laboratory and teaches undergraduate courses in telecommunication networks, data transmission and switching and traffic theory, and graduate courses in wireless, mobile and personal networks, teletraffic engineering and planning, and broadband multiservices networks. In 2000 she joined the Center for PersonKommunikation, Aalborg University, Denmark, as a visiting professor and during 2001--2002 she held a position of associate research professor at the same university. Currently she holds a part-time position of associated research professor with Center for Teleinfrastructur (CTIF). Prof. Gavrilovska was involved in several EU (ACTS ASAP, IST PACWOMAN, MAGNET, TEMPUS) and national/international projects. She published numerous conference and journal papers and participated in several workshops. At the moment she is working on the book “Ad Hoc Networking Towards Seamless Communications” together with prof. R. Prasad. Her research interests include wireless and personal area networks, ad hoc networking, networking protocols, traffic analysis, QoS, and optimization techniques. She is a senior member of IEEE and serves as a Chair of Macedonian Communication Chapter. 相似文献
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To provide responsive information services in a ubiquitous computing environment, service software and system development are indispensable. A component-based ubiquitous information system with a JAIN (Java APIs for Integrated Networks) platform to achieve seamless transmissions and reach-everywhere communications was designed in our research. In this development, numerous ubiquitous service modules were identified: location management, roaming, mobile IP and WAP networking. These component-based network modules were constructed using a component composition language with component specification and interface definition, running on top of a distributed service architecture using a JAIN platform to distribute the ubiquitous information services to mobile users. Two applications, Wireless-Application-Protocol (WAP) Mail and Video-on-Demand (VoD) services, show that the JAIN-like platform with the developed networking components effectively fills the gap for application developers between mobile appliances and various kinds of ubiquitous information services. 相似文献
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Dynamic Survivability in WDM Mesh Networks Under Dynamic Traffic 总被引:3,自引:0,他引:3
Network survivability is a crucial requirement in WDM mesh networks. In this paper, we systematically consider the problem of dynamic survivability with dynamic single link failure in WDM networks under dynamic traffic demands. Specifically, we investigate various protection schemes, such as dedicated path protection (DPP), shared path protection (SPP), dedicated link protection (DLP), shared link protection (SLP), and two restoration schemes, path restoration (PR) and link restoration (LR). Moreover, two new shared protection methods are proposed, i.e., SRLG-based shared link protection (SRLG-SLP) and SRLG-based shared path protection (SRLG-SPP). The SRLG (shared risk link group) constraint defines the availability of protection resources to a working path, which requires that any two working paths sharing the same risk of failure (or in the same SRLG) cannot share the same protection resources. Furthermore, in our study, we consider a more practical dynamic single-link failure model, in which the link-failure-interarrival time and link-failure-holding time are considered as two independent parameters. Based on this link-failure model, extensive simulations are done to analyze and compare the dynamic survivable performance of various protection and restoration schemes. Resource utilization, protection efficiency, restoration efficiency, and service disruption ratio are employed as survivable performance metrics versus traffic load, link-failure frequency, and link-failure reparation time to evaluate the survivable performance. Many meaningful results are given. In addition, we show that the developed SRLG-SLP and SRLG-SPP protection schemes perform very well in terms of protection efficiency and service disruption ratio, while sacrificing some performance in terms of resource utilization. 相似文献