Routing is a challenging task in Wireless Sensor Networks (WSNs) due to the limitation in energy and hardware capabilities in WSN nodes. This challenge prompted researchers to develop routing protocols that satisfy WS...Routing is a challenging task in Wireless Sensor Networks (WSNs) due to the limitation in energy and hardware capabilities in WSN nodes. This challenge prompted researchers to develop routing protocols that satisfy WSNs needs. The main design objectives are reliable delivery, low energy consumption, and prolonging network lifetime. In WSNs, routing is based on local information among neighboring nodes. Routing decisions are made locally;each node will select the next hop without any clue about the other nodes on the path. Although a full knowledge about the network yields better routing, that is not feasible in WSNs due to memory limitation and to the high traffic needed to collect the needed data about all the nodes in the network. As an effort to try to overcome this disadvantage, we are proposing in this paper aware diffusion routing protocol. Aware diffusion follows a semi-holistic approach by collecting data about the available paths and uses these data to enforce healthier paths using machine learning. The data gathering is done by adding a new stage called data collection stage. In this stage, the protocol designer can determine which parameters to collect then use these parameters in enforcing the best path according to certain criteria. In our implementation of this paradigm, we are collecting total energy on the path, lowest energy level on the path, and hop count. Again, the data collected is designer and application specific. The collected data will be used to compare available paths using non-incremental learning, and the outcome will be preferring paths that meet the designer criteria. In our case, healthier and shorter paths are preferred, which will result in less power consumption, higher delivery rate, and longer network life since healthier and fewer nodes will be doing the work.展开更多
A sensitive and selective zinc ion ratiometric fluorescence sensor has been synthesized and characterized. This material displays dual fluorescence. After the material was bonded to a closed-shell metal ion, such as ...A sensitive and selective zinc ion ratiometric fluorescence sensor has been synthesized and characterized. This material displays dual fluorescence. After the material was bonded to a closed-shell metal ion, such as Zn2＋, the recovery of the local excited fluorescence of the material-Zn2＋ complex, largely at the expense of the intramolecular charge transfer fluorescence, is consistent with the difference between selected orbital transitions of the free dye and the metal-chelated complex. For instance, the contribution of the πtpy→πtpy, transition becomes more prominent. This is also consistent with the results of the fluorescence decay behavior, measured via a time-correlated single photon counting setup. In contrast, the corresponding open shell Ni2＋ -bound complex quenches both kinds of photoluminescence, due to spin-orbit coupling.展开更多
基于光时域反射技术(Optical Time Domain Reflectometry, OTDR)的光纤分布式传感器可以实现对整个传感光纤空间可分辨的分布式测量,相比点式传感器具有极大的技术及应用成本优势。而传统的基于模拟探测的OTDR光纤分布式传感器在空间分...基于光时域反射技术(Optical Time Domain Reflectometry, OTDR)的光纤分布式传感器可以实现对整个传感光纤空间可分辨的分布式测量,相比点式传感器具有极大的技术及应用成本优势。而传统的基于模拟探测的OTDR光纤分布式传感器在空间分辨率及动态范围上存在性能瓶颈。基于单光子探测的光子计数OTDR光纤分布式传感系统通过数字化的探测和记录方式,可以突破传统OTDR系统的性能极限。本文对光子计数OTDR系统技术及发展进行了综述,旨在通过本文的综述,明确基于单光子探测的光子计数OTDR系统的优势及限制,以及该技术的未来发展趋势,促进基于OTDR技术的光纤分布式传感器的进一步发展。展开更多
文摘Routing is a challenging task in Wireless Sensor Networks (WSNs) due to the limitation in energy and hardware capabilities in WSN nodes. This challenge prompted researchers to develop routing protocols that satisfy WSNs needs. The main design objectives are reliable delivery, low energy consumption, and prolonging network lifetime. In WSNs, routing is based on local information among neighboring nodes. Routing decisions are made locally;each node will select the next hop without any clue about the other nodes on the path. Although a full knowledge about the network yields better routing, that is not feasible in WSNs due to memory limitation and to the high traffic needed to collect the needed data about all the nodes in the network. As an effort to try to overcome this disadvantage, we are proposing in this paper aware diffusion routing protocol. Aware diffusion follows a semi-holistic approach by collecting data about the available paths and uses these data to enforce healthier paths using machine learning. The data gathering is done by adding a new stage called data collection stage. In this stage, the protocol designer can determine which parameters to collect then use these parameters in enforcing the best path according to certain criteria. In our implementation of this paradigm, we are collecting total energy on the path, lowest energy level on the path, and hop count. Again, the data collected is designer and application specific. The collected data will be used to compare available paths using non-incremental learning, and the outcome will be preferring paths that meet the designer criteria. In our case, healthier and shorter paths are preferred, which will result in less power consumption, higher delivery rate, and longer network life since healthier and fewer nodes will be doing the work.
基金Supported by the National Natural Science Foundation of China(Nos20633070, 20833008)the National Key Basic Research Special Foundation of China(Nos2007CB815202)
文摘A sensitive and selective zinc ion ratiometric fluorescence sensor has been synthesized and characterized. This material displays dual fluorescence. After the material was bonded to a closed-shell metal ion, such as Zn2＋, the recovery of the local excited fluorescence of the material-Zn2＋ complex, largely at the expense of the intramolecular charge transfer fluorescence, is consistent with the difference between selected orbital transitions of the free dye and the metal-chelated complex. For instance, the contribution of the πtpy→πtpy, transition becomes more prominent. This is also consistent with the results of the fluorescence decay behavior, measured via a time-correlated single photon counting setup. In contrast, the corresponding open shell Ni2＋ -bound complex quenches both kinds of photoluminescence, due to spin-orbit coupling.
文摘基于光时域反射技术(Optical Time Domain Reflectometry, OTDR)的光纤分布式传感器可以实现对整个传感光纤空间可分辨的分布式测量,相比点式传感器具有极大的技术及应用成本优势。而传统的基于模拟探测的OTDR光纤分布式传感器在空间分辨率及动态范围上存在性能瓶颈。基于单光子探测的光子计数OTDR光纤分布式传感系统通过数字化的探测和记录方式,可以突破传统OTDR系统的性能极限。本文对光子计数OTDR系统技术及发展进行了综述,旨在通过本文的综述,明确基于单光子探测的光子计数OTDR系统的优势及限制,以及该技术的未来发展趋势,促进基于OTDR技术的光纤分布式传感器的进一步发展。
