检索结果-南通市图书馆

Design of tightly linked dual ring antenna and imaging of magnetic field distribution using a diamond fiber probe

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第2期33卷 347-352页

作者：叶青云薛雅文何飞越赵旭彤卞雨辰卢文韬王金旭陈鸿浩夏圣开曾明菁杜关祥 College of Telecommunications and Information engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China College of science Nanjing University of Posts and TelecommunicationsNanjing 210003China school of computer science Nanjing University of Posts and TelecommunicationsNanjing 210023China Bell Honors school Nanjing University of Posts and TelecommunicationsNanjing 210023China

A tightly linked dual ring antenna is designed,and it is specifically tailored for uniformly coupling the microwave magnetic field to the nitrogen-vacancy(NV)*** designed antenna operates at a center frequency of about 2.87 GHz,with a bandwidth of around 200 MHz,allowing it to address multiple resonance peaks in the optically detected magnetic resonance(ODMR)spectrum in an external magnetic ***,the antenna generates a fairly uniform magnetic field in a range with a radius of 0.75 *** resolution imaging of the magnetic field distribution on the surface of the antenna is conducted by using a fiber diamond *** also investigate the effect of magnetic field uniformity on the linewidth of ODMR,so as to provide insights into reducing the inhomogeneous broadening of ODMR.

关键词： nitrogen vacancy(NV) microwave(MW)imaging inhomogeneous broadening

A Self-certified Cross-Cluster Asymmetric Group Key Agreement for Wireless Sensor Networks

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2019年第2期28卷 280-287页

作者： ZHANG Qikun LI Yongjiao ZHANG Quanxin YUAN junling wang Ruifang GAN Yong TAN Yu'an Institute of computer and Communication engineering Zhengzhou University of Light Industry school of computer science and Technology Beijing Institute of Technology

Wireless sensor networks have some obvious characteristics, such as communication range is limited, computing power is limited and energy is limited. Group key agreement in this environment requires a cross-cluster, computation and communication overhead are lightweight and highly safe group key agreement protocol. Aiming at these demands, the paper proposes a Self-certified cross-cluster Asymmetric group key agreement(SC-AGKA). To establish a lightweight and efficient group communication channel among sensor nodes. According to the cluster head as the bridge node to realize the sensor nodes in different cluster have the same group key information, and negotiate a pair of asymmetric group keys to realize the cross cluster secure communication. The group communication adopts asymmetric encryption mechanism. It realizes the group security communication mechanism of message sender unconstraint. The asymmetric group key agreement has the key self-certified, which does not need additional rounds to verify the correctness of group key. Proven and analysis show that the proposed protocol has the advantages of in security and energy consumption.

关键词： Wireless sensor networks Asymmetric group key agreement Authenticated protocol Key self-confirmation

Effects of information transmission delay and channel blocking on synchronization in scale-free Hodgkin-Huxley neuronal networks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2011年第6期27卷 1052-1058页

作者： Qing-yun wang Yan-Hong Zheng Department of Dynamics and Control Beihang University 100191 Beijing China school of Mathematics and computer science Fujian Normal University 350007 Fuzhou China

In this paper,we investigate the evolution of spatiotemporal patterns and synchronization transitions in dependence on the information transmission delay and ion channel blocking in scale-free neuronal *** the underlying model of neuronal dynamics,we use the Hodgkin-Huxley equations incorporating channel blocking and intrinsic *** is shown that delays play a significant yet subtle role in shaping the dynamics of neuronal *** particular,regions of irregular and regular propagating excitatory fronts related to the synchronization transitions appear intermittently as the delay ***,the fraction of working sodium and potassium ion channels can also have a significant impact on the spatiotemporal dynamics of neuronal *** the fraction of blocked sodium channels increases,the frequency of excitatory events decreases,which in turn manifests as an increase in the neuronal synchrony that,however,is dysfunctional due to the virtual absence of large-amplitude ***,we also show that larger coupling strengths improve synchronization irrespective of the information transmission delay and channel *** presented results are also robust against the variation of the network size,thus providing insights that could facilitate understanding of the joint impact of ion channel blocking and information transmission delay on the spatiotemporal dynamics of neuronal networks.

关键词： Scale-free neuronal networks - Information transmission delay Ion channel blocking Synchronization

Bamboo Leaf and Pollen Fossils from the Late Miocene of Eastern Zhejiang,China and their Phytogeological Significance

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2014年第4期88卷 1066-1083页

作者： wang Qiujun MA Fujun YANG Yi DONG junling wang Haofei LI Ruiyun XU Xiaohui SUN Bainian school of Earth sciences & Key Laboratory of Mineral Resources in Western China (Gansu Province) Lanzhou University

Fossil bamboo leaves and pollen from Upper Miocene deposits of the Shengxian Formation in Tiantai and Ninghai counties, eastern Zhejiang, China represent a rare record in Asia. The distinctive pseudopetiole and parallel venation of the leaf blades and the clearly thickened annulus of the pollen aperture place them in the subfamily Bambusoideae. Morphological analysis supports the determination of these fossil leaves as belonging to the genus Bambusium and two new species are described. Bambusium latipseudopetiolus Q.J. wang et B.N. Sun sp. nov. has a distinctly wide pseudopetiole of 0.23 cm in width and 0.40 cm in length, several vascular bundles on parallel veins, and 5-8 lateral veins on both sides of the midrib. Bambusium longipseudopetiolus Q.J. wang et B.N. Sun sp. nov. has a distinctly long pseudopetiole of 0.60 cm in length and 0.10 cm in width, several vascular bundles on the pseudopetiole, and 6 lateral veins on both sides of the midrib. Pollen grains from the same layer provide additional evidence of bamboos. They are characterized by 32.0-51.0 μm in diameter, a round pore 3.0-4.0 μm in diameter with a broad thickened annulus 2.5-3.5 μm around, and several conspicuous secondary folds on the exine surface. The morphological analysis leads to their assignment to Graminidites bambusoides Stuchlik. These fossils are important for the study of bamboo phytogeography in China. They demonstrate that there were bamboos growing in southeastern China during the Late Miocene and that bamboos in Zhejiang begin to diversify no later than the Late Miocene. In combination with bamboo fossils from other places, it seems that bamboos had a wide distribution across southern China during the Miocene, ranging from southwestern yun＇nan to southeastern Zhejiang.

关键词： Paleobotany Palynology Phytogeography Bambusoideae Late Miocene Zhejiang province

A Convolutional Network Coding Oriented Four-Stage Contention Protocol for All-to-All Broadcasting Networks

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2016年第1期25卷 192-198页

作者： LIU yun wang Shan ZHU Bocheng school of Electronics engineering and computer science Peking University

Most practical networks are cyclic and demand Convolutional network coding(CNC). Researches on application of CNC in practical networks are still insufficient. Conventional graph theories cannot model the multicast channel properly. This paper introduces a multicast graph with multicast edges to model the multicast networks, and proposes a Multicast edge generation and max-flow detection(MEGAMAD) algorithm to approach the lower bound of necessary multicast edge number for a multicast network. Based on the algorithm we designed a new Media access control(MAC) protocol, the CNC oriented four-stage contention protocol(NC-FSCP) for the all-to-all broadcasting networks. The protocol runs a four stage reservation procedure to reserve time slots for encoded data transmission. Simulation proves that the reserved slot number approaches the lower bound for data dispersion in an all-to-all broadcasting network.

关键词： Convolutional network coding(CNC) MAC Multicast networks Max-flow min-cut

Necessary and sufficient checkpoint selection for temporal verification of high-confidence cloud workflow systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science China(Information sciences) 2015年第5期58卷 33-48页

作者： wang FuTian LIU Xiao YANG yun school of computer science and Technology Anhui University Shanghai Key Laboratory of Trustworthy Computing East China Normal University school of Software and Electrical engineering Swinburne University of Technology

On-time completion is an important temporal Qo S(Quality of Service) dimension and one of the fundamental requirements for high-confidence workflow systems. In recent years, a workflow temporal verification framework, which generally consists of temporal constraint setting, temporal checkpoint selection, temporal verification, and temporal violation handling, has been the major approach for the high temporal Qo S assurance of workflow systems. Among them, effective temporal checkpoint selection, which aims to timely detect intermediate temporal violations along workflow execution plays a critical role. Therefore, temporal checkpoint selection has been a major topic and has attracted significant efforts. In this paper, we will present an overview of workflow temporal checkpoint selection for temporal verification. Specifically, we will first introduce the throughput based and response-time based temporal consistency models for business and scientific cloud workflow systems,respectively. Then the corresponding benchmarking checkpoint selection strategies that satisfy the property of"necessity and sufficiency" are presented. We also provide experimental results to demonstrate the effectiveness of our checkpoint selection strategies, and finally points out some possible future issues in this research area.

关键词： workflow system workflow temporal verification temporal checkpoint selection business workflow scientific workflow quality of se

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

混合云环境面向安全科学工作流数据布局策略

计算机工程与设计 2024年第7期45卷 2004-2012页

作者：苏明辉林兵卢宇王素云福建师范大学物理与能源学院福建福州350117 北京大学信息科学技术学院北京100871 福建师范大学协和学院福建福州350117

为解决混合云环境下科学工作流数据布局问题,在考虑数据的安全需求的前提下,以优化跨数据中心传输时延为目标,提出了一种混合云环境下面向安全的科学工作流布局策略。分析数据集的安全需求以及数据中心所能提供的安全服务,提出安全等级... 详细信息

为解决混合云环境下科学工作流数据布局问题,在考虑数据的安全需求的前提下,以优化跨数据中心传输时延为目标,提出了一种混合云环境下面向安全的科学工作流布局策略。分析数据集的安全需求以及数据中心所能提供的安全服务,提出安全等级分级规则;设计并提出基于遗传算法和模拟退火算法的自适应粒子群优化算法(adaptive particle swarm optimization algorithm based on SA and GA,SAGA-PSO),避免算法陷入局部极值,有效提高种群多样性;与其它经典布局算法对比,基于SAGA-PSO的数据布局策略在满足数据安全需求的同时能够大大降低传输时延。

关键词：混合云科学工作流数据布局安全分级时延优化遗传粒子群优化算法模拟退火

Operations Research in the Blockchain Technology

在线全文

学校读者我要写书评

暂无评论

Journal of the Operations Research Society of China 2022年第2期10卷 401-422页

作者： Xu wang Ling-yun Wu IAM MADISNCMISAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China school of Mathematical sciences University of Chinese Academy of SciencesBeijing 100049China Department of Industrial engineering Tsinghua UniversityBeijing 100084China

In the past decade,as a decentralized distributed database technology blockchain has developed rapidly at an unprecedented speed and been applied to a wide range of scenarios far beyond cryptocurrencies,for example,insurance,energy,risk management,and Internet of things(IoT).The blockchain technology combines the achievements from cryptography,computer science,economics,and operations research and has increasingly attracted attention from both academia and *** the operations research has been widely adopted in the blockchain technology,there is a lack of comprehensive survey on the operations research in blockchain-related *** order to fill the gap,we analyze the blockchain technology through the perspective of operations research and present a comprehensive review of the operations research problems from the aspects of security and stability,efficiency and performance,and resource *** paper aimed to help the relevant readers in the field of operations research find their own points of interest and conduct in-depth research on the blockchain technology,hoping to promote the rapid development and wider application of the blockchain technology in the near future.

关键词： Blockchain Operations research Security Efficiency Resource allocation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

基于边缘特征和注意力机制的图像语义分割

计算机系统应用 2024年第7期33卷 63-73页

作者：王军张霁云程勇南京信息工程大学计算机学院南京210044 南京信息工程大学科技产业处南京210044

在语义分割任务中,编码器的下采样过程会导致分辨率降低,造成图像空间信息细节的丢失,因此在物体边缘会出现分割不连续或者错误分割的现象,进而对整体分割性能产生负面影响.针对上述问题,提出基于边缘特征和注意力机制的图像语义分割模... 详细信息

在语义分割任务中,编码器的下采样过程会导致分辨率降低,造成图像空间信息细节的丢失,因此在物体边缘会出现分割不连续或者错误分割的现象,进而对整体分割性能产生负面影响.针对上述问题,提出基于边缘特征和注意力机制的图像语义分割模型EASSNet.首先,使用边缘检测算子计算原始图像的边缘图,通过池化下采样和卷积运算提取边缘特征.接着,将边缘特征融合到经过编码器提取的深层语义特征当中,恢复经过下采样的特征图像的空间细节信息,并且通过注意力机制来强化有意义的信息,从而提高物体边缘分割的准确性,进而提升语义分割的整体性能.最后,EASSNet在PASCAL VOC 2012和Cityscapes数据集上的平均交并比分别达到85.9%和76.7%,与当前流行的语义分割网络相比,整体分割性能和物体边缘的分割效果都具有明显优势.

关键词：语义分割空间细节信息边缘特征特征融合注意力机制