检索结果-南通市图书馆

EduASAC:A Blockchain-Based Education Archive Sharing and Access Control System

Computers, Materials & Continua 2023年第12期77卷 3387-3422页

作者： Ronglei Hu Chuce He Yaping Chi Xiaoyi Duan Xiaohong Fan Ping Xu Wenbin Gao department of electronics and communication Engineering Beijing Electronic Science and Technology InstituteBeijing100070China department of Cyberspace Security Beijing Electronic Science and Technology InstituteBeijing100070China

In the education archive sharing system,when performing homomorphic ciphertext retrieval on the storage server,there are problems such as low security of shared data,confusing parameter management,and weak access control.This paper proposes an Education Archives Sharing and Access Control(EduASAC)system to solve these problems.The system research goal is to realize the sharing of security parameters,the execution of access control,and the recording of system behaviors based on the blockchain network,ensuring the legitimacy of shared membership and the security of education archives.At the same time,the system can be combined with most homomorphic ciphertext retrieval schemes running on the storage server,making the homomorphic ciphertext retrieval mechanism controllable.This paper focuses on the blockchain access control framework and specifically designs smart contracts that conform to the business logic of the EduASAC system.The former adopts a dual-mode access control mechanism combining Discretionary Access Control(DAC)and Mandatory Access Control(MAC)and improves the tagging mode after user permission verification based on the Authentication and Authorization for Constrained Environments(ACE)authorization framework of Open Authorization(OAuth)2.0;the latter is used in the system to vote on nodes to join requests,define access control policies,execute permission verification processes,store,and share system parameters,and standardize the behavior of member nodes.Finally,the EduASAC system realizes the encryption,storage,retrieval,sharing,and access control processes of education archives.To verify the performance of the system,simulation experiments were conducted.The results show that the EduASAC system can meet the high security needs of education archive sharing and ensure the system’s high throughput,low latency,fast decision-making,and fine-grained access control ability.

关键词： Blockchain data security access control smart contract

来源：

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

Research of Ultrafine Cemented Carbides for PCB Microdrills

引用

Journal of Wuhan University of technology(Materials Science) 2021年第2期36卷 255-258页

作者：张卫丰李春霞 Department of Electronic and Communication Technology Shenzhen Institute of Information TechnologyShenzhen 518172China

The nanocrystalline WC-10Co composite powders were produced with the processing method of spray thermal decomposition-continuous reduction&carburization.The grain growth inhibitors of 0.4wt%Cr_(3)C_(2) and 0.4wt%VC were added into the composite powders to obtain advanced ultrafine hardmetals with minimal porosity,defects and discontinuous.The rod samples were formed by extrusion.They were sintered in cacuum with SIP treatment.The sintered rods were made into PCB microdrill samples after polishing.Mechanical properties(such as density,hardness,transverse rupture strenth(TRS),magnetic saturation induction and magnetic coercivity)of the sintered ultrafine cemented carbides were measured.The microstructures of them were investigated by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The experimental results show that the transverse rupture strength of the samples sintered in vacuum with sinterhip(SIP)treatment is more excellent.The grain size could be controlled in a range of 200-400 nm with the help of grain growth inhibitors.And the superfine grained materials have superior strength(3900 MPa)and high hardness(HRA=93.3).These features are ideal for PCB microdrills.

关键词： nanocrystalline WC-10Co cemented carbide nanocomposite PCB microdrills

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multi-feature Multimodal Biometric Recognition Based on Quaternion Locality Preserving Projection

引用

Chinese Journal of electronics 2019年第4期28卷 789-796页

作者： WANG Zhifang ZHEN Jiaqi LI Yanchao LI Guoqiang HAN Qi department of electronic Engineering Heilongjiang University department of Information Security and communication technology Norwegian University of Science and Technology department of Computer Science and technology Harbin Institute of Technology

This paper proposed Quaternion locality preserving projection(QLPP) for multi-feature multimodal biometric recognition. Multi-features fill the real part or the three imaginary parts of quaternion to constitute the quaternion fusion features. In quaternion division ring, QLPP extracts the local information and finds essential manifold structure of the quaternion fusion features. Deferent from Quaternion principal component analysis(QPCA) and Quaternion fisher discriminant analysis(QFDA), QLPP takes advantage of the optimal linear approximations to find the nonlinear manifold structures. Two experiments are designed: one fuses four features from two biometric modalities, and the other fuses three features from three biometric modalities.The experimental results show the proposed algorithm achieves much better performance than the unimodal biometric algorithms, the traditional feature level fusion methods(weighted sum rule and series rule) and two quaternion representation methods(QPCA and QFDA).

关键词： Multimodal biometrics Quaternion Feature fusion Quaternion locality preserving projection(QLPP)

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Influence analysis of calculated horizontally layered soil parameters on grounding parameters

引用

High Voltage 2023年第2期8卷 421-430页

作者： Yihua Dan Junjun Yin Jian Yang Huizhang Yang department of electronic Engineering Tsinghua UniversityBeijingChina School of Computer&communication Engineering University of Science and Technology BeijingBeijingChina

Calculated parameters(soil layer resistivity,soil layer thickness,and the number of soil layers)of horizontally layered soil are usually obtained based on the measured apparent resistivity under different measurement distances,which are significant for the design,operation,and maintenance of grounding grids.Most existing calculation methods of soil parameters are just trying to make the calculation results approach the measurement data,ignoring the relationship among measurement data,the calculated soil parameters,and grounding parameters,which would increase the workload of the measurement.To better balance the distance range of the measurement data and the influence of the calculated horizontally layered soil on grounding parameters,this paper systematically studies the relationship among measured apparent soil resistivity,calculated horizontally layered soil parameters,and grounding parameters.The basic theories of apparent resistivity measurement,soil parameter calculation,and grounding parameter calculation are given,the influence of soil layer thickness on the measured apparent resistivity is studied,and the influence of the calculated soil parameters on the grounding resistance of different grounding models is analysed.Based on different scales of grounding grids,the results give a corresponding reference distance range of measured apparent soil resistivity.Therefore,this paper can help decrease the workload of soil resistivity measurement during grounding parameters analysis,which has far-reaching engineering significance.

关键词： soil parameters apparent

来源：

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

Time and energy efficient data collection via UAV

引用

Science China(Information Sciences) 2022年第8期65卷 182-196页

作者： Tianhao WANG Xiaowei PANG Jie TANG Nan ZHAO Xiuyin ZHANG Xianbin WANG School of Information and communication Engineering Dalian University of Technology department of Electrical and Computer Engineering Western University School of electronic and Information Engineering South China University of Technology

Using unmanned aerial vehicles(UAVs) for data collection has emerged as a promising technique to achieve both time-and energy-efficient data gathering while keeping data fresh. In this study, two schemes are proposed for flight cycle minimization and energy efficiency maximization to collect data from ground sensors. We first minimize the flight cycle by jointly optimizing the wake-up scheduling of sensors, the trajectory,and the time slot, which is a mixed-integer non-convex problem and difficult to solve directly. To this end,we propose an iterative algorithm based on block coordinate descent and successive convex approximation to decouple the original non-convex problem into two sub-problems and the constraints are turned to be convex approximately. Furthermore, the energy efficiency is maximized since the limited energy is a critical issue in UAV communication systems. We approximate the two subproblems as convex optimizations by introducing slack variables and applying SCA. The approximate energy efficiency is a fractional expression, and we use Dinkelbach’s method to solve it. Numerical results show that the flight cycle is minimized in the first scheme with the data requirement satisfied, while in the second scheme, the energy efficiency is maximized with the trade-off between the transmission data and the propulsion power consumption.

关键词： data collection energy efficiency maximization time minimization trajectory optimization unmanned aerial vehicle (UAV)

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Recent advances in breathable electronics

引用

Nano Research 2023年第3期16卷 4130-4142页

作者： Zhuocheng Yan Jian Xiong Bin Wang Min Gao Guangqiang Yin Tao Hu Taisong Pan Xinzhong Wang Yuan Lin department of electronic communication and technology Shenzhen Institute of Information TechnologyShenzhen 518172China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 610054China School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Engineering Cooperation on Applied Medicine Research Center University of Electronic Science and Technology of ChinaChengdu 610054China

The successful implementation of bioelectronic devices attached to living organism hinges on a number of material and device characteristics,including not only electrical and mechanical performances to gather physiological signals from living organism thus enabling status monitoring,but also permeability or breathability for gas/nutrient exchange between living organisms and surroundings to ensure minimum perturbation of the intrinsic biological function.However,most bioelectronic devices built on planar polymeric substrates,such as polydimethylsiloxane(PDMS),polyurethane(PU),and polyimide(PI),lack efficient gas permeability,which may hinder the emission of volatile compounds from the surface of living organism,affecting the natural metabolism and reducing the comfort of wearing.Thus,achieving permeability or breathability in bioelectronic devices is a significant challenge.Currently,the devices made of gas-permeable materials with porous structures,that combine electronic components with daily garments,such as fibric and textile,offer exciting opportunities for breathable electronics.In this review,several types of gas-permeable materials with their synthesis and processing routes are outlines.Then,two methods for measuring water vapor transmission rate of materials are discussed in depth.Finally,recent progress in the use of gaspermeable materials for the applications of plant-and skin-attached electronics is summarized systematically.

关键词： breathability gas permeability porous sponge foam nano materials plant electronics wearable electronics

来源：

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

Improving the intensity and efficiency of compressed echo in rare-earth-ion-doped crystal

引用

Chinese Physics B 2016年第7期25卷 124-130页

作者：马秀荣梁裕卿王松张双根单云龙 department of Computer and communication Engineering Tianjin University of Technology Engineering Research Center of communication Devices and technology Ministry of Education Tianjin Key Laboratory of Film electronic and communication Devices

We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation（AWG）. A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-iondoped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo＇s intensity and efficiency. The theoretical analysis is validated by numerical simulations.

关键词： intensity and efficiency compressed echo arbitrary waveform generation optical Bloch equations

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Pulse Propagation with Self-Phase Modulation in Nonlinear Chiral Fiber and Its Applications

引用

Chinese Physics Letters 2016年第9期33卷 47-51页

作者： Demissie Gelmecha 李俊庆 Merhawit Teklu department of Physics Harbin Institute of Technology department of electronic Science and technology Harbin Institute of Technology communication Research Center Harbin Institute of Technology

From Maxwell’s equations and Post’s formalism,a generalized chiral nonlinear Schrodinger equation(CNLSE) is obtained for the nonlinear chiral fiber.This equation governs light transmission through a dispersive nonlinear chiral fiber with joint action of chirality in linear and nonlinear ways.The generalized CNLSE shows a modulation of chirality to the effect of attenuation and nonlinearity compared with the case for a conventional fiber.Simulations based on the split-step beam propagation method reveal the role of nonlinearity with cooperation to chirality playing in the pulse evolution.By adjusting its strength the role of chirality in forming solitons is demonstrated for a given circularly polarized component.The application of nonlinear optical rotation is also discussed in an all-optical switch.

关键词： of on for in Pulse Propagation with Self-Phase Modulation in Nonlinear Chiral Fiber and Its Applications with that is

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A 4-quadrant Curvelet Transform for Denoising Digital Images

引用

International Journal of Automation and computing 2013年第3期10卷 217-226页

作者： P. K. Parlewar K. M. Bhurchandi department of electronic and communication Engineering Ramdeobaba College of Engineering and Management department of electronic Engineering Visvesvaraya National Institute of Technology

The conventional discrete wavelet transform （DWT） introduces artifacts during denoising of images containing smooth curves. Finite ridgelet transform （FRIT） solved this problem by mapping the curves in terms of small curved ridges. However, blind application of FRIT all over an image is computationally heavy. Finite curvelet transform （FCT） selectively applies FRIT only to the tiles containing small portions of a curve. In this work, a novel curvelet transform named as 4-quadrant finite curvelet transform （4QFCT） based on a new concept of 4-quadrant finite ridgelet transform （4QFRIT） has been proposed. An image is band pass filtered and the high frequency bands are divided into small non-overlapping square tiles. The 4QFRIT is applied to the tiles containing at least one curve element. Unlike FRIT, the 4QFRIT takes 4 sets of radon projections in all the 4 quadrants and then averages them in time and frequency domains after denoising. The proposed algorithm is extensively tested and benchmarked for denoising of images with Gaussian noise using mean squared error （MSE） and peak signal to noise ratio （PSNR）. The results confirm that 4QFCT yields consistently better denoising performance quantitatively and visually.

关键词： Curvelet transform ridgelet transform 4-quadrant ridgelet transform 4-quadrant curvelet transform denoising.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Range resolution and sampling frequency trade-off for GPS passive radar

引用

Journal of Systems Engineering and electronics 2022年第1期33卷 28-37页

作者： ZHANG Zhuxian ZHENG Yu ZHENG Linhua ZHU Peidong College of electronic Science National University of Defense TechnologyChangsha 410073China College of electronic communication and Electrical Engineering Changsha UniversityChangsha 410022China

In a global positioning system(GPS)passive radar,a high resolution requires a high sampling frequency,which increases the computational load.Balancing the computational load and the range resolution is challenging.This paper presents a method to trade off the range resolution and the computational load by experimentally determining the optimal sampling frequency through an analysis of multiple sets of GPS satellite data at different sampling frequencies.The test data are used to construct a range resolution-sampling frequency trade-off model using least-squares estimation.The theoretical analysis shows that the experimental data are the best fit using smoothing and nthorder derivative splines.Using field GPS C/A code signal-based GPS radar,the trade-off between the optimal sampling frequency is determined to be in the 20461.25–24553.5 kHz range,which supports a resolution of 43–48 m.Compared with the conventional method,the CPU time is reduced by approximately 50%.

关键词： global positioning system(GPS)radar range resolution sampling frequency trade-off

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：