检索结果-南通市图书馆

BVDFed:Byzantine-resilient and verifiable aggregation for differentially private federated learning

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2024年第5期18卷 171-187页

作者： Xinwen GAO Shaojing FU Lin LIU yuchuan luo College of Computer National University of Defence TechnologyChangsha 410000China

Federated Learning(FL)has emerged as a powerful technology designed for collaborative training between multiple clients and a server while maintaining data privacy of *** enhance the privacy in FL,Differentially Private Federated Learning(DPFL)has gradually become one of the most effective *** DPFL operates in the distributed settings,there exist potential malicious adversaries who manipulate some clients and the aggregation server to produce malicious parameters and disturb the learning ***,existing aggregation protocols for DPFL concern either the existence of some corrupted clients(Byzantines)or the corrupted *** protocols are limited to eliminate the effects of corrupted clients and server when both are in existence simultaneously due to the complicated threat *** this paper,we elaborate such adversarial threat model and propose *** our best knowledge,it is the first Byzantine-resilient and Verifiable aggregation for Differentially privateFEDerated *** specific,wepropose Differentially Private Federated Averaging algorithm(DPFA)asour primary workflow of BVDFed,which ismore lightweight and easily portable than traditional DPFL *** then introduce Loss Score to indicate the trustworthiness of disguised gradients in *** on Loss Score,we propose an aggregation rule DPLoss to eliminate faulty gradients from Byzantine clients during server aggregation while preserving the privacy of clients'***,we design a secure verification scheme DPVeri that are compatible with DPFA and DPLoss to support the honest clients in verifying the integrity of received aggregated *** DPVeri also provides resistance to collusion attacks with no more than t participants for our *** analysis and experimental results demonstrate our aggregation to be feasible and effective in practice.

关键词： federated learning differential private verifiable aggregation Byzantine fault-tolerance

Spatiotemporal patterns of winter wheat phenology and its climatic drivers based on an improved pDSSAT model

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

Science China Earth Sciences 2021年第1期64卷 2144-2160页

作者： yuchuan luo Zhao ZHANG Liangliang ZHANG Juan CAO Academy of Disaster Reduction and Emergency Management Minsitry of Emergency Management&Ministry of Education School of National Safety and Emergency ManagementBeijing Normal UniversityBeijing100875China

Acquiring spatiotemporal patterns of phenological information and its drivers is essential for understanding the response of crops to climate change and implementing adaptation ***,current approaches to obtain phenology and analyse its drivers have deficiencies such as sparse observations,excessive dependence of remote sensing inversion on sensors,and inevitable difficulties in upscaling site-based crop models into larger *** on the Wang-Engel temperature response function,we improved the Crop Estimation through Resource and Environment Synthesis-Wheat(CERES-Wheat)***,we calibrated the model at the regional scale and evaluated its ***,the spatiotemporal changes in winter wheat phenology in China from 2000 to 2015 were *** results showed that the improved model significantly enhanced the simulation accuracy of the anthesis and maturity dates by averages of 13%and 12%in most planting areas,especially in the Yunnan-Guizhou Plateau(YG)with improvements of 26%and 28%.The simulated phenology of winter wheat grown in a colder environment(e.g.,the average temperatures during the vegetative growth period range from 0 to 5℃ and from 15 to 20°C,and the reproductive growth period ranges from 10 to 15°C)also notably *** results confirmed that the original temperature response function indeed had *** analyses revealed that the key phenological dates and growth periods over the past 16 years were dominantly advanced and ***,the anthesis date,vegetative growth period(VGP),and reproductive growth period(RGP)indicated obviously spatial *** example,the anthesis date and VGP in the North China Plain(NCP)and the Middle-Lower Yangtze Plain(YZ)and the RGP in northwestern China(NW)showed opposite trends of delay and prolongation as comparing with the dominant *** analysis indicated that the key phenological dates and growth periods were advanced and sho

关键词： Winter wheat Phenology Temperature response function Spatiotemporal patterns pDSSAT

同方期刊数据库

Damage evaluation of soybean chilling injury based on Google Earth Engine(GEE)and crop modelling

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2020年第8期30卷 1249-1265页

作者： CAO Juan ZHANG Zhao ZHANG Liangliang luo yuchuan LI Ziyue TAO Fulu State Key Laboratory of Earth Surface Processes and Resource Ecology/MEM&MoE Key Laboratory of Environmental Change and Natural Hazards Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

Frequent chilling injury has serious impacts on national food security and in northeastern China heavily affects grain *** and accurate measures are desirable for assessing associated large-scale impacts and are prerequisites to disaster ***,we propose a novel means to efficiently assess the impacts of chilling injury on *** chilling injury events were diagnosed in 1989,1995,2003,2009,and 2018 in Oroqen *** total,512 combinations scenarios were established using the localized CROPGRO-Soybean ***,we determined the maximum wide dynamic vegetation index(WDRVI)and corresponding date of critical windows of the early and late growing seasons using the GEE(Google Earth Engine)platform,then constructed 1600 cold vulnerability models on CDD(Cold Degree Days),the simulated LAI(Leaf Area Index)and yields from the CROPGRO-Soybean ***,we calculated pixel yields losses according to the corresponding vulnerability *** findings show that simulated historical yield losses in 1989,1995,2003 and 2009 were measured at 9.6%,29.8%,50.5%,and 15.7%,respectively,closely(all errors are within one standard deviation)reflecting actual losses(6.4%,39.2%,47.7%,and 13.2%,respectively).The above proposed method was applied to evaluate the yield loss for 2018 at the pixel ***,a sentinel-2A image was used for 10-m high precision yield mapping,and the estimated losses were found to characterize the actual yield losses from 2018 cold *** results highlight that the proposed method can efficiently and accurately assess the effects of chilling injury on soybean crops.

关键词： chilling injury Google Earth Engine(GEE) CROPGRO-Soybean soybean yield loss cold degree days(CDD)

Enable Data Dynamics for Algebraic Signatures Based Remote Data Possession Checking in the Cloud Storage

在线全文

学校读者我要写书评

暂无评论

China Communications 2014年第11期11卷 114-124页

作者： luo yuchuan FU Shaojing XU Ming WANG Dongsheng College of Computer National University of Defense Technology Changsha 410073 Hunan Province P. R. China Science and Technology on Information Assurance Laboratory Beijing 100000 P. R. China

Cloud storage is one of the main application of the cloud *** the data services in the cloud,users is able to outsource their data to the cloud,access and share their outsourced data from the cloud server anywhere and ***,this new paradigm of data outsourcing services also introduces new security challenges,among which is how to ensure the integrity of the outsourced *** the cloud storage providers commit a reliable and secure environment to users,the integrity of data can still be damaged owing to the carelessness of humans and failures of hardwares/softwares or the attacks from external ***,it is of great importance for users to audit the integrity of their data outsourced to the *** this paper,we first design an auditing framework for cloud storage and proposed an algebraic signature based remote data possession checking protocol,which allows a third-party to auditing the integrity of the outsourced data on behalf of the users and supports unlimited number of *** we extends our auditing protocol to support data dynamic operations,including data update,data insertion and data *** analysis and experiment results demonstrate that our proposed schemes are secure and efficient.

关键词： cloud computing cloud storage data integrity algebraic signatures datadynamics

Erosion research of CX-2002U carbon composites under low-temperature high-flux hydrogen plasma

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2021年第2期23卷 93-100页

作者： Hengxin GUO Zongbiao YE Bizhou SHEN Jianjun WEI Bo WANG yuchuan luo Kun ZHANG Fujun GOU Jianjun CHEN Bo CHEN Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610064People's Republic of China Institute of Nuclear Science and Technology Sichuan UniversityChengdu 610064People's Republic of China

The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma *** is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma *** the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would *** the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed ***,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias *** on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.

关键词： carbon fiber composites hydrogen plasma chemical erosion redeposition nanoparticle

在线全文

学校读者我要写书评

暂无评论

基于LT码的损坏数据探测与动态更新方案

工程科学与技术 2018年第5期50卷 145-151页

作者：徐明黄宇锋付绍静罗玉川国防科技大学计算机学院湖南长沙410073 密码科学技术国家重点实验室北京100878 信息保障技术国防科技重点实验室北京100072

随着云存储的日益普及,确保数据的安全性与可用性也越来越重要,然而数据损坏的情况不可避免,因此如何能够快速探测出损坏数据,是一个亟待解决的问题。已有基于LT编码的云存储方案与基于认证跳跃表的云存储方案对数据用户来说具有较高的... 详细信息

随着云存储的日益普及,确保数据的安全性与可用性也越来越重要,然而数据损坏的情况不可避免,因此如何能够快速探测出损坏数据,是一个亟待解决的问题。已有基于LT编码的云存储方案与基于认证跳跃表的云存储方案对数据用户来说具有较高的通信开销与计算开销,负担较重。作者基于LT编码设计了两级分布式二叉树的云存储方案。该方案通过对探测数据建立两级分布式二叉树结构,利用BLS签名的聚合性质对数据块进行计算并生成聚合标签,验证聚合标签是否正确以定位出损坏数据所处的位置,提升了探测损坏数据块的效率;同时,基于LT码的编码性质,对更新数据块进行异或运算,实现了数据的动态更新并且能对云服务器是否进行数据更新进行验证,从而解决快速准确探测损坏数据与数据动态更新的问题,且该方案具有较好的整体性能。实验结果表明:所设计的方案是基于LT编码的两级分布式二叉树的方案,在损坏数据探测方面,与基于LT编码的逐一探测损坏数据方案相比,存储开销相当,但是计算开销与通信开销大大减少;在数据动态更新方面,与基于RS编码的动态更新方案相比,存储开销与通信开销相当,但是计算开销大大减少。

关键词：云存储 LT码 BLS签名动态更新

在线全文

学校读者我要写书评

暂无评论

微型电网中基于联盟链的需求侧竞价方案

郑州大学学报（理学版） 2020年第3期52卷 120-126页

作者：吴皓敏付绍静徐明罗玉川国防科技大学计算机学院湖南长沙410003

需求响应是解决微型电网电力供求平衡问题的有效方案。然而传统的中心化管理方案不能很好适用于具有分布式特点的微型电网,存在中心难以被信任、单点失效等问题。提出一种基于联盟区块链的需求响应管理框架,设计具有多账本存储、域内节... 详细信息

需求响应是解决微型电网电力供求平衡问题的有效方案。然而传统的中心化管理方案不能很好适用于具有分布式特点的微型电网,存在中心难以被信任、单点失效等问题。提出一种基于联盟区块链的需求响应管理框架,设计具有多账本存储、域内节点背书特点的联盟链。该框架通过不可篡改的联盟链存储需求响应记录,并利用自我强制执行的智能合约对各过程进行计算,可以有效加强微型电网需求响应中多方之间的相互信任。此外,在该框架之上,提出基于智能合约的去中心化需求侧竞价方案,并采用二分法实现分布式竞价的快速收敛。

关键词：微型电网需求响应联盟链需求侧竞价

基于Google Earth Engine和作物模型快速评估低温冷害对大豆生产的影响

在线全文

学校读者我要写书评

暂无评论

地理学报 2020年第9期75卷 1879-1892页

作者：曹娟张朝张亮亮骆玉川李子悦陶福禄环境演变与自然灾害教育部重点实验室/地表过程与资源生态国家重点实验室北京师范大学地理科学学部北京100875 中国科学院地理科学与资源研究所中国科学院陆地表层格局与模拟重点实验室北京100101

作为中国商品粮的主要生产基地,东北地区频发的低温冷害给中国粮食安全带来了严重的影响,及时、准确和大范围评估低温冷害灾损是降低损失、快速恢复生产的重要前提。本文以鄂伦春为例,提出了一种快速评估低温冷害对大豆生产影响的新方... 详细信息

作为中国商品粮的主要生产基地,东北地区频发的低温冷害给中国粮食安全带来了严重的影响,及时、准确和大范围评估低温冷害灾损是降低损失、快速恢复生产的重要前提。本文以鄂伦春为例,提出了一种快速评估低温冷害对大豆生产影响的新方法。首先诊断出该地区典型冷害事件发生的年份为1989年、1995年、2003年、2009年和2018年;然后基于本地化后CROPGRO-Soybean模型设置512组低温冷害和田间管理组合模拟情景;其次构建了1600组包括3个变量(有效积温距平值(CDD)、模拟的叶面积植被指数(LAI)和产量)的冷害脆弱性模型;最后依托Google Earth Engine(GEE)平台逐像元提取大豆关键生育期早晚窗口内最大的宽动态植被指数(WDRVI)及对应的日期(DOY),将WDRVI转化为大豆种植格点的实际LAI,结合构建的冷害脆弱性模型逐像元计算出产量和减产率。主要发现如下:①校准后的CROPGRO-Soybean模型能较为准确地模拟不同冷害情景下的大豆生长发育过程;②大豆遭受全生育期的降温情景(1~3℃)的减产幅度比局部降温情景(4个生育期随机生成连续5日温度为0℃)的减产幅度大;③历史冷害年1989年、1995年、2003年、2009年平均减产率约为9.6%、29.8%、50.5%和15.7%,与实际6.4%、39.2%、47.7%和13.2%的减产率相比,冷害灾损评估结果具有较好的精度且误差均在一倍方差以内;④运用该方法评估2018年冷害田间尺度的产量损失,并利用Sentinel-2A影像进行10 m高精度制图。结果显示,该方法能够快速、准确地评估不同尺度的低温冷害灾损情况,为作物估产以及农作物灾害损失评估的业务化运行提供了新的思路。

关键词：低温冷害 Google Earth Engine(GEE) CROPGRO-Soybean 大豆减产率有效积温距平值(CDD)

在线全文

学校读者我要写书评

暂无评论

凹头弹丸垂直入水仿真研究

兵工学报 2020年第S1期41卷 128-134页

作者：黄振贵罗驭川陈志华侯宇唐楚淳南京理工大学瞬态物理国家重点实验室江苏南京210094 航天动力测控技术研究所陕西西安710025

凹头弹丸是一种含有部分中空腔体的结构,在以头部开空腔部分首先冲击自由液面的过程中,空腔内气相-液相两相耦合,与弹丸形成复杂的固相、液相、气相三相运动。为分析凹头弹丸在低速垂直入水条件下弹丸头部形状和内部空腔对入水空泡及弹... 详细信息

凹头弹丸是一种含有部分中空腔体的结构,在以头部开空腔部分首先冲击自由液面的过程中,空腔内气相-液相两相耦合,与弹丸形成复杂的固相、液相、气相三相运动。为分析凹头弹丸在低速垂直入水条件下弹丸头部形状和内部空腔对入水空泡及弹道特性的影响,采用数值模拟方法研究不同凹腔深度的凹头弹丸入水过程空泡流动变化,并将其与平头弹垂直入水过程进行对比,得到了入水瞬间各弹丸能量耗散程度的规律以及入水后加速度、阻力系数以及速度的变化趋势。结果表明:不同弹丸入水空泡有着较明显的区别;平头弹丸与凹头弹丸运动入水开孔泡阶段,头部压力骤增,形成阶段头部压力减小,表面闭合阶段头部压力又开始骤增。

关键词：凹头弹丸垂直入水空腔弹道特性耦合