A common and critical operation for wireless sensor networks is data gathering. The efficient clustering of a sensor network that can save energy and improve coverage efficiency is an important requirement for many up...A common and critical operation for wireless sensor networks is data gathering. The efficient clustering of a sensor network that can save energy and improve coverage efficiency is an important requirement for many upper layer network functions. This study concentrates on how to form clusters with high uniformity while prolonging the network lifetime. A novel clustering scheme named power- and coverage- aware clustering （PCC） is proposed, which can adaptively select cluster heads according to a hybrid of the nodesI residual energy and loyalty degree. Additionally, the PCC scheme is independent of node distribution or density, and it is free of node hardware limitations, such as self-locating capability and time synchronization. Experiment results show that the scheme performs well in terms of cluster size （and its standard deviation）, number of nodes alive over time, total energy consumption, etc.展开更多
主要研究了SiC雪崩光电二极管(APD)阵列对微弱紫外光的探测均匀性问题,设计并制备了1×128 SiC APD探测阵列,通过表征各像素点的电流-电压曲线,提取出APD阵列的击穿电压波动在±0.1 V;通过被动淬灭电路表征各像素点的微弱紫外...主要研究了SiC雪崩光电二极管(APD)阵列对微弱紫外光的探测均匀性问题,设计并制备了1×128 SiC APD探测阵列,通过表征各像素点的电流-电压曲线,提取出APD阵列的击穿电压波动在±0.1 V;通过被动淬灭电路表征各像素点的微弱紫外光探测能力,提取出APD阵列的暗计数率波动在±0.5 Hz/μm^(2),单光子探测效率波动在±0.4%,良率达到91%,结果表明本工作设计的SiC APD探测阵列能够为微弱紫外光成像技术提供可行的技术方案。展开更多
Crossbar array provides a cost-effective approach for achieving high-density integration of two-terminal functional devices. However, the ＂sneaking current problem＂, which can lead to read failure, is a severe chall...Crossbar array provides a cost-effective approach for achieving high-density integration of two-terminal functional devices. However, the ＂sneaking current problem＂, which can lead to read failure, is a severe challenge in crossbar arrays. To inhibit the sneaking current from unselected cells, the integration of individual selection devices is necessary. In this work, we report a novel TaOx-based selector exhibiting a trapezoidal band structure formed by tuning the concentration of defects in the oxide. Salient features such as a high current density （1 MA·cm^-2）, high selectivity （5 × 10^4）, low off-state current （-10 pA）, robust endurance （〉10^10）, self-compliance, and excellent uniformity were successfully achieved. The integrated one-selector one-resistor （1S1R） device exhibits high nonlinearity in the low resistance state （LRS）, which is quite effective in solving the sneaking current issue.展开更多
基金supported by National Basic Research Program of China (No. 2010CB731800)National Natural Science Foundation of China (No. 60934003)Educational Foundation of Hebei Province (No. 2008147)
文摘A common and critical operation for wireless sensor networks is data gathering. The efficient clustering of a sensor network that can save energy and improve coverage efficiency is an important requirement for many upper layer network functions. This study concentrates on how to form clusters with high uniformity while prolonging the network lifetime. A novel clustering scheme named power- and coverage- aware clustering （PCC） is proposed, which can adaptively select cluster heads according to a hybrid of the nodesI residual energy and loyalty degree. Additionally, the PCC scheme is independent of node distribution or density, and it is free of node hardware limitations, such as self-locating capability and time synchronization. Experiment results show that the scheme performs well in terms of cluster size （and its standard deviation）, number of nodes alive over time, total energy consumption, etc.
基金Acknowledgements This work was supported by the National Key Research and Development Program of China （Nos. 2016YFA0203800 and 2016YFA0201803） and the National Natural Science Foundation of China （No. 61522408）.
文摘Crossbar array provides a cost-effective approach for achieving high-density integration of two-terminal functional devices. However, the ＂sneaking current problem＂, which can lead to read failure, is a severe challenge in crossbar arrays. To inhibit the sneaking current from unselected cells, the integration of individual selection devices is necessary. In this work, we report a novel TaOx-based selector exhibiting a trapezoidal band structure formed by tuning the concentration of defects in the oxide. Salient features such as a high current density （1 MA·cm^-2）, high selectivity （5 × 10^4）, low off-state current （-10 pA）, robust endurance （〉10^10）, self-compliance, and excellent uniformity were successfully achieved. The integrated one-selector one-resistor （1S1R） device exhibits high nonlinearity in the low resistance state （LRS）, which is quite effective in solving the sneaking current issue.
