期刊文献+
共找到56,479篇文章
< 1 2 250 >
每页显示 20 50 100
从习语看“云”和“cloud”的隐喻比较 被引量:1
1
作者 张荣 《山西农业大学学报(社会科学版)》 2011年第4期402-405,共4页
习语是语言的精华,有着深厚的社会历史渊源和丰富的文化内涵。通过分析"云"隐喻在习语中的种种隐喻和比较汉英两种语言中有关"云"隐喻的历史渊源和文化内涵,以发现"云"隐喻在这两种文化中的共性和差异。... 习语是语言的精华,有着深厚的社会历史渊源和丰富的文化内涵。通过分析"云"隐喻在习语中的种种隐喻和比较汉英两种语言中有关"云"隐喻的历史渊源和文化内涵,以发现"云"隐喻在这两种文化中的共性和差异。并在此基础上,对隐喻的翻译做了初步探讨。 展开更多
关键词 隐喻 汉语 英语
下载PDF
“I Wandered Lonely as a Cloud”的元功能分析
2
作者 黄妍 《韶关学院学报》 2019年第7期97-100,共4页
元功能思想是系统功能语言学的核心,对语言学研究有重要的影响。“I Wandered Lonely as a Cloud”是华慈华斯自然诗篇的代表作,从元功能框架下的概念功能、人际功能和语篇功能三方面对其进行考察,揭示元功能在诗歌结构构建、运用语言... 元功能思想是系统功能语言学的核心,对语言学研究有重要的影响。“I Wandered Lonely as a Cloud”是华慈华斯自然诗篇的代表作,从元功能框架下的概念功能、人际功能和语篇功能三方面对其进行考察,揭示元功能在诗歌结构构建、运用语言形式体现诗人自然生态观方面的作用,也证明了元功能分析诗歌作品的可操作性。 展开更多
关键词 系统功能语言学 元功能 IWanderedLonelyasacloud
下载PDF
基于Spring Cloud的分布式医疗数据平台建设
3
作者 汪睿 胡珊珊 +1 位作者 陈敏莲 徐骁 《设备管理与维修》 2024年第4期16-19,共4页
为解决互联网时代医疗大数据的可靠存储问题,探索异构数据的有效处理方案,加强医疗数据检索能力。提出一种基于Spring Cloud的分布式医疗数据平台建设方案,该方案通过Spring Cloud技术构建分布式架构,选取MongoDB非关系型数据库作为分... 为解决互联网时代医疗大数据的可靠存储问题,探索异构数据的有效处理方案,加强医疗数据检索能力。提出一种基于Spring Cloud的分布式医疗数据平台建设方案,该方案通过Spring Cloud技术构建分布式架构,选取MongoDB非关系型数据库作为分布式存储,同时对数据进行标准化、分词等操作,从而实现一个异构数据可存储、系统高可用、规模易扩展、检索高效率的医疗数据平台。 展开更多
关键词 分布式 医疗数据 Spring cloud MONGODB
下载PDF
基于Spring Cloud微服务架构的非物质文化遗产展示与学习系统的设计与实现
4
作者 杜俊 李金忠 +1 位作者 何新武 李志鸿 《广东轻工职业技术学院学报》 2024年第1期14-21,共8页
针对目前人民群众对非物质文化遗产认识不够全面,以及市面上利用系统软件来有效保护和传承非物质文化遗产的软件很缺乏等问题,结合相应软件开发技术和数字可视化技术,设计和实现了一款非物质文化遗产展示与学习系统以实现对非物质文化... 针对目前人民群众对非物质文化遗产认识不够全面,以及市面上利用系统软件来有效保护和传承非物质文化遗产的软件很缺乏等问题,结合相应软件开发技术和数字可视化技术,设计和实现了一款非物质文化遗产展示与学习系统以实现对非物质文化遗产项目的传承和保护创新。本系统以江西省范围内的主要非物质文化遗产项目为例,设置有移动App端和PC端,采用前后端分离的开发模式,以当前主流的Spring Cloud微服务架构技术为基础,结合SpringBoot框架,在华为云服务器上搭建起弹性可伸缩的后端服务。使用Uni-App开发移动端,以解决无法在Android、IOS及各大小程序平台运行的问题。经测试,本系统具有操作简单,易于使用、维护和扩展,高并发性等优点。 展开更多
关键词 非物质文化遗产 Spring cloud微服务架构 Uni-App框架 Vue框架 ECharts可视化图表
下载PDF
Cloudless-Training:基于serverless的高效跨地域分布式ML训练框架
5
作者 谭文婷 吕存驰 +1 位作者 史骁 赵晓芳 《高技术通讯》 CAS 北大核心 2024年第3期219-232,共14页
跨地域分布式机器学习(ML)训练能够联合多区域的云资源协作训练,可满足许多新兴ML场景(比如大型模型训练、联邦学习)的训练需求。但其训练效率仍受2方面挑战的制约。首先,多区域云资源缺乏有效的弹性调度,这会影响训练的资源利用率和性... 跨地域分布式机器学习(ML)训练能够联合多区域的云资源协作训练,可满足许多新兴ML场景(比如大型模型训练、联邦学习)的训练需求。但其训练效率仍受2方面挑战的制约。首先,多区域云资源缺乏有效的弹性调度,这会影响训练的资源利用率和性能;其次,模型跨地域同步需要在广域网(WAN)上高频通信,受WAN的低带宽和高波动的影响,会产生巨大通信开销。本文提出Cloudless-Training,从3个方面实现高效的跨地域分布式ML训练。首先,它基于serverless计算模式实现,使用控制层和训练执行层的2层架构,支持多云区域的弹性调度和通信。其次,它提供一种弹性调度策略,根据可用云资源的异构性和训练数据集的分布自适应地部署训练工作流。最后,它提供了2种高效的跨云同步策略,包括基于梯度累积的异步随机梯度下降(ASGD-GA)和跨云参数服务器(PS)间的模型平均(MA)。Cloudless-Training是基于OpenFaaS实现的,并被部署在腾讯云上评估,实验结果表明Cloudless-Training可显著地提高跨地域分布式ML训练的资源利用率(训练成本降低了9.2%~24.0%)和同步效率(训练速度最多比基线快1.7倍),并能保证模型的收敛精度。 展开更多
关键词 跨地域分布式机器学习(ML)训练 跨云ML训练 分布式训练框架 serverless 跨云模型同步
下载PDF
基于RuoYi-Cloud的劳动教育平台建设
6
作者 张家铭 周杰 周北平 《电子技术应用》 2024年第3期92-99,共8页
为帮助学生学习劳动文化、进行劳动实践,辅助教师精准地安排和开展劳动教学活动,设计且实现了一款基于RuoYi-Cloud框架的劳动教育系统,具有劳动教育管理、选课管理、在线学习、学业预警、系统监控、数据分析等功能,使用RuoYi-Cloud框架... 为帮助学生学习劳动文化、进行劳动实践,辅助教师精准地安排和开展劳动教学活动,设计且实现了一款基于RuoYi-Cloud框架的劳动教育系统,具有劳动教育管理、选课管理、在线学习、学业预警、系统监控、数据分析等功能,使用RuoYi-Cloud框架开发降低了开发和维护成本,提高了开发效率。采用微服务架构,实现对用户友好的界面和高度可扩展的后端功能,优化了系统的响应时间和资源利用率确保系统高效运行,系统的灵活性和扩展性为未来的功能扩展提供良好的基础。系统为劳动教育实施提供可靠解决方案,通过对系统的实际应用和用户反馈,系统对劳动教育领域有一定参考价值。 展开更多
关键词 劳动教育 RuoYi-cloud 微服务 低代码
下载PDF
The Spatiotemporal Distribution Characteristics of Cloud Types and Phases in the Arctic Based on CloudSat and CALIPSO Cloud Classification Products
7
作者 Yue SUN Huiling YANG +5 位作者 Hui XIAO Liang FENG Wei CHENG Libo ZHOU Weixi SHU Jingzhe SUN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第2期310-324,共15页
The cloud type product 2B-CLDCLASS-LIDAR based on CloudSat and CALIPSO from June 2006 to May 2017 is used to examine the temporal and spatial distribution characteristics and interannual variability of eight cloud typ... The cloud type product 2B-CLDCLASS-LIDAR based on CloudSat and CALIPSO from June 2006 to May 2017 is used to examine the temporal and spatial distribution characteristics and interannual variability of eight cloud types(high cloud, altostratus, altocumulus, stratus, stratocumulus, cumulus, nimbostratus, and deep convection) and three phases(ice,mixed, and water) in the Arctic. Possible reasons for the observed interannual variability are also discussed. The main conclusions are as follows:(1) More water clouds occur on the Atlantic side, and more ice clouds occur over continents.(2)The average spatial and seasonal distributions of cloud types show three patterns: high clouds and most cumuliform clouds are concentrated in low-latitude locations and peak in summer;altostratus and nimbostratus are concentrated over and around continents and are less abundant in summer;stratocumulus and stratus are concentrated near the inner Arctic and peak during spring and autumn.(3) Regional averaged interannual frequencies of ice clouds and altostratus clouds significantly decrease, while those of water clouds, altocumulus, and cumulus clouds increase significantly.(4) Significant features of the linear trends of cloud frequencies are mainly located over ocean areas.(5) The monthly water cloud frequency anomalies are positively correlated with air temperature in most of the troposphere, while those for ice clouds are negatively correlated.(6) The decrease in altostratus clouds is associated with the weakening of the Arctic front due to Arctic warming, while increased water vapor transport into the Arctic and higher atmospheric instability lead to more cumulus and altocumulus clouds. 展开更多
关键词 cloudSat and CALIPSO cloud type cloud phase temporal and spatial distribution interannual variation
下载PDF
Cloud Datacenter Selection Using Service Broker Policies:A Survey
8
作者 Salam Al-E’mari Yousef Sanjalawe +2 位作者 Ahmad Al-Daraiseh Mohammad Bany Taha Mohammad Aladaileh 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第4期1-41,共41页
Amid the landscape of Cloud Computing(CC),the Cloud Datacenter(DC)stands as a conglomerate of physical servers,whose performance can be hindered by bottlenecks within the realm of proliferating CC services.A linchpin ... Amid the landscape of Cloud Computing(CC),the Cloud Datacenter(DC)stands as a conglomerate of physical servers,whose performance can be hindered by bottlenecks within the realm of proliferating CC services.A linchpin in CC’s performance,the Cloud Service Broker(CSB),orchestrates DC selection.Failure to adroitly route user requests with suitable DCs transforms the CSB into a bottleneck,endangering service quality.To tackle this,deploying an efficient CSB policy becomes imperative,optimizing DC selection to meet stringent Qualityof-Service(QoS)demands.Amidst numerous CSB policies,their implementation grapples with challenges like costs and availability.This article undertakes a holistic review of diverse CSB policies,concurrently surveying the predicaments confronted by current policies.The foremost objective is to pinpoint research gaps and remedies to invigorate future policy development.Additionally,it extensively clarifies various DC selection methodologies employed in CC,enriching practitioners and researchers alike.Employing synthetic analysis,the article systematically assesses and compares myriad DC selection techniques.These analytical insights equip decision-makers with a pragmatic framework to discern the apt technique for their needs.In summation,this discourse resoundingly underscores the paramount importance of adept CSB policies in DC selection,highlighting the imperative role of efficient CSB policies in optimizing CC performance.By emphasizing the significance of these policies and their modeling implications,the article contributes to both the general modeling discourse and its practical applications in the CC domain. 展开更多
关键词 cloud computing cloud service broker datacenter selection QUALITY-OF-SERVICE user request
下载PDF
Intelligent Solution System for Cloud Security Based on Equity Distribution:Model and Algorithms
9
作者 Sarah Mustafa Eljack Mahdi Jemmali +3 位作者 Mohsen Denden Mutasim Al Sadig Abdullah M.Algashami Sadok Turki 《Computers, Materials & Continua》 SCIE EI 2024年第1期1461-1479,共19页
In the cloud environment,ensuring a high level of data security is in high demand.Data planning storage optimization is part of the whole security process in the cloud environment.It enables data security by avoiding ... In the cloud environment,ensuring a high level of data security is in high demand.Data planning storage optimization is part of the whole security process in the cloud environment.It enables data security by avoiding the risk of data loss and data overlapping.The development of data flow scheduling approaches in the cloud environment taking security parameters into account is insufficient.In our work,we propose a data scheduling model for the cloud environment.Themodel is made up of three parts that together help dispatch user data flow to the appropriate cloudVMs.The first component is the Collector Agent whichmust periodically collect information on the state of the network links.The second one is the monitoring agent which must then analyze,classify,and make a decision on the state of the link and finally transmit this information to the scheduler.The third one is the scheduler who must consider previous information to transfer user data,including fair distribution and reliable paths.It should be noted that each part of the proposedmodel requires the development of its algorithms.In this article,we are interested in the development of data transfer algorithms,including fairness distribution with the consideration of a stable link state.These algorithms are based on the grouping of transmitted files and the iterative method.The proposed algorithms showthe performances to obtain an approximate solution to the studied problem which is an NP-hard(Non-Polynomial solution)problem.The experimental results show that the best algorithm is the half-grouped minimum excluding(HME),with a percentage of 91.3%,an average deviation of 0.042,and an execution time of 0.001 s. 展开更多
关键词 Cyber-security cloud computing cloud security ALGORITHMS HEURISTICS
下载PDF
Performance Comparison of Hyper-V and KVM for Cryptographic Tasks in Cloud Computing
10
作者 Nader Abdel Karim Osama A.Khashan +4 位作者 Waleed K.Abdulraheem Moutaz Alazab Hasan Kanaker Mahmoud E.Farfoura Mohammad Alshinwan 《Computers, Materials & Continua》 SCIE EI 2024年第2期2023-2045,共23页
As the extensive use of cloud computing raises questions about the security of any personal data stored there,cryptography is being used more frequently as a security tool to protect data confidentiality and privacy i... As the extensive use of cloud computing raises questions about the security of any personal data stored there,cryptography is being used more frequently as a security tool to protect data confidentiality and privacy in the cloud environment.A hypervisor is a virtualization software used in cloud hosting to divide and allocate resources on various pieces of hardware.The choice of hypervisor can significantly impact the performance of cryptographic operations in the cloud environment.An important issue that must be carefully examined is that no hypervisor is completely superior in terms of performance;Each hypervisor should be examined to meet specific needs.The main objective of this study is to provide accurate results to compare the performance of Hyper-V and Kernel-based Virtual Machine(KVM)while implementing different cryptographic algorithms to guide cloud service providers and end users in choosing the most suitable hypervisor for their cryptographic needs.This study evaluated the efficiency of two hypervisors,Hyper-V and KVM,in implementing six cryptographic algorithms:Rivest,Shamir,Adleman(RSA),Advanced Encryption Standard(AES),Triple Data Encryption Standard(TripleDES),Carlisle Adams and Stafford Tavares(CAST-128),BLOWFISH,and TwoFish.The study’s findings show that KVM outperforms Hyper-V,with 12.2%less Central Processing Unit(CPU)use and 12.95%less time overall for encryption and decryption operations with various file sizes.The study’s findings emphasize how crucial it is to pick a hypervisor that is appropriate for cryptographic needs in a cloud environment,which could assist both cloud service providers and end users.Future research may focus more on how various hypervisors perform while handling cryptographic workloads. 展开更多
关键词 cloud computing performance VIRTUALIZATION hypervisors HYPER-V KVM cryptographic algorithm
下载PDF
Evolutionary fingerprint, phylogenetic and forest structure of tropical montane Atlantic cloud forests along an elevation gradient
11
作者 Ravi Fernandes MARIANO Vanessa Leite REZENDE +7 位作者 Cléber Rodrigo de SOUZA Patrícia Vieira POMPEU Rubens Manoel dos SANTOS Carolina Njaime MENDES Aloysio Souza de MOURA Felipe Santana MACHADO Warley Augusto Caldas CARVALHO Marco Aurélio Leite FONTES 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1259-1271,共13页
Environmental conditions can change markedly over geographical distances along elevation gradients,making them natural laboratories to study the processes that structure communities.This work aimed to assess the influ... Environmental conditions can change markedly over geographical distances along elevation gradients,making them natural laboratories to study the processes that structure communities.This work aimed to assess the influences of elevation on Tropical Montane Cloud Forest plant communities in the Brazilian Atlantic Forest,a historically neglected ecoregion.We evaluated the phylogenetic structure,forest structure(tree basal area and tree density)and species richness along an elevation gradient,as well as the evolutionary fingerprints of elevation-success on phylogenetic lineages from the tree communities.To do so,we assessed nine communities along an elevation gradient from 1210 to 2310 m a.s.l.without large elevation gaps.The relationships between elevation and phylogenetic structure,forest structure and species richness were investigated through Linear Models.The occurrence of evolutionary fingerprint on phylogenetic lineages was investigated by quantifying the extent of phylogenetic signal of elevation-success using a genus-level molecular phylogeny.Our results showed decreased species richness at higher elevations and independence between forest structure,phylogenetic structure and elevation.We also verified that there is a phylogenetic signal associated with elevation-success by lineages.We concluded that the elevation is associated with species richness and the occurrence of phylogenetic lineages in the tree communities evaluated in Mantiqueira Range.On the other hand,elevation is not associated with forest structure or phylogenetic structure.Furthermore,closely related taxa tend to have their higher ecological success in similar elevations.Finally,we highlight the fragility of the tropical montane cloud forests in the Mantiqueira Range in face of environmental changes(i.e.global warming)due to the occurrence of exclusive phylogenetic lineages evolutionarily adapted to environmental conditions(i.e.minimum temperature)associated with each elevation range. 展开更多
关键词 Atlantic Forest cloud forest CONSERVATION Community ecology Montane forests Phylogenetic diversity Phylogenetic signal
下载PDF
Securing Cloud-Encrypted Data:Detecting Ransomware-as-a-Service(RaaS)Attacks through Deep Learning Ensemble
12
作者 Amardeep Singh Hamad Ali Abosaq +5 位作者 Saad Arif Zohaib Mushtaq Muhammad Irfan Ghulam Abbas Arshad Ali Alanoud AlMazroa 《Computers, Materials & Continua》 SCIE EI 2024年第4期857-873,共17页
Data security assurance is crucial due to the increasing prevalence of cloud computing and its widespread use across different industries,especially in light of the growing number of cybersecurity threats.A major and ... Data security assurance is crucial due to the increasing prevalence of cloud computing and its widespread use across different industries,especially in light of the growing number of cybersecurity threats.A major and everpresent threat is Ransomware-as-a-Service(RaaS)assaults,which enable even individuals with minimal technical knowledge to conduct ransomware operations.This study provides a new approach for RaaS attack detection which uses an ensemble of deep learning models.For this purpose,the network intrusion detection dataset“UNSWNB15”from the Intelligent Security Group of the University of New South Wales,Australia is analyzed.In the initial phase,the rectified linear unit-,scaled exponential linear unit-,and exponential linear unit-based three separate Multi-Layer Perceptron(MLP)models are developed.Later,using the combined predictive power of these three MLPs,the RansoDetect Fusion ensemble model is introduced in the suggested methodology.The proposed ensemble technique outperforms previous studieswith impressive performance metrics results,including 98.79%accuracy and recall,98.85%precision,and 98.80%F1-score.The empirical results of this study validate the ensemble model’s ability to improve cybersecurity defenses by showing that it outperforms individual MLPmodels.In expanding the field of cybersecurity strategy,this research highlights the significance of combined deep learning models in strengthening intrusion detection systems against sophisticated cyber threats. 展开更多
关键词 cloud encryption RAAS ENSEMBLE threat detection deep learning CYBERSECURITY
下载PDF
Point Cloud Classification Using Content-Based Transformer via Clustering in Feature Space
13
作者 Yahui Liu Bin Tian +2 位作者 Yisheng Lv Lingxi Li Fei-Yue Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第1期231-239,共9页
Recently, there have been some attempts of Transformer in 3D point cloud classification. In order to reduce computations, most existing methods focus on local spatial attention,but ignore their content and fail to est... Recently, there have been some attempts of Transformer in 3D point cloud classification. In order to reduce computations, most existing methods focus on local spatial attention,but ignore their content and fail to establish relationships between distant but relevant points. To overcome the limitation of local spatial attention, we propose a point content-based Transformer architecture, called PointConT for short. It exploits the locality of points in the feature space(content-based), which clusters the sampled points with similar features into the same class and computes the self-attention within each class, thus enabling an effective trade-off between capturing long-range dependencies and computational complexity. We further introduce an inception feature aggregator for point cloud classification, which uses parallel structures to aggregate high-frequency and low-frequency information in each branch separately. Extensive experiments show that our PointConT model achieves a remarkable performance on point cloud shape classification. Especially, our method exhibits 90.3% Top-1 accuracy on the hardest setting of ScanObjectN N. Source code of this paper is available at https://github.com/yahuiliu99/PointC onT. 展开更多
关键词 Content-based Transformer deep learning feature aggregator local attention point cloud classification
下载PDF
A Blockchain and CP-ABE Based Access Control Scheme with Fine-Grained Revocation of Attributes in Cloud Health
14
作者 Ye Lu Tao Feng +1 位作者 Chunyan Liu Wenbo Zhang 《Computers, Materials & Continua》 SCIE EI 2024年第2期2787-2811,共25页
The Access control scheme is an effective method to protect user data privacy.The access control scheme based on blockchain and ciphertext policy attribute encryption(CP–ABE)can solve the problems of single—point of... The Access control scheme is an effective method to protect user data privacy.The access control scheme based on blockchain and ciphertext policy attribute encryption(CP–ABE)can solve the problems of single—point of failure and lack of trust in the centralized system.However,it also brings new problems to the health information in the cloud storage environment,such as attribute leakage,low consensus efficiency,complex permission updates,and so on.This paper proposes an access control scheme with fine-grained attribute revocation,keyword search,and traceability of the attribute private key distribution process.Blockchain technology tracks the authorization of attribute private keys.The credit scoring method improves the Raft protocol in consensus efficiency.Besides,the interplanetary file system(IPFS)addresses the capacity deficit of blockchain.Under the premise of hiding policy,the research proposes a fine-grained access control method based on users,user attributes,and file structure.It optimizes the data-sharing mode.At the same time,Proxy Re-Encryption(PRE)technology is used to update the access rights.The proposed scheme proved to be secure.Comparative analysis and experimental results show that the proposed scheme has higher efficiency and more functions.It can meet the needs of medical institutions. 展开更多
关键词 Blockchain access-control CP-ABE cloud health
下载PDF
Part-Whole Relational Few-Shot 3D Point Cloud Semantic Segmentation
15
作者 Shoukun Xu Lujun Zhang +2 位作者 Guangqi Jiang Yining Hua Yi Liu 《Computers, Materials & Continua》 SCIE EI 2024年第3期3021-3039,共19页
This paper focuses on the task of few-shot 3D point cloud semantic segmentation.Despite some progress,this task still encounters many issues due to the insufficient samples given,e.g.,incomplete object segmentation an... This paper focuses on the task of few-shot 3D point cloud semantic segmentation.Despite some progress,this task still encounters many issues due to the insufficient samples given,e.g.,incomplete object segmentation and inaccurate semantic discrimination.To tackle these issues,we first leverage part-whole relationships into the task of 3D point cloud semantic segmentation to capture semantic integrity,which is empowered by the dynamic capsule routing with the module of 3D Capsule Networks(CapsNets)in the embedding network.Concretely,the dynamic routing amalgamates geometric information of the 3D point cloud data to construct higher-level feature representations,which capture the relationships between object parts and their wholes.Secondly,we designed a multi-prototype enhancement module to enhance the prototype discriminability.Specifically,the single-prototype enhancement mechanism is expanded to the multi-prototype enhancement version for capturing rich semantics.Besides,the shot-correlation within the category is calculated via the interaction of different samples to enhance the intra-category similarity.Ablation studies prove that the involved part-whole relations and proposed multi-prototype enhancement module help to achieve complete object segmentation and improve semantic discrimination.Moreover,under the integration of these two modules,quantitative and qualitative experiments on two public benchmarks,including S3DIS and ScanNet,indicate the superior performance of the proposed framework on the task of 3D point cloud semantic segmentation,compared to some state-of-the-art methods. 展开更多
关键词 Few-shot point cloud semantic segmentation CapsNets
下载PDF
Numerical Investigation of the Angle of Attack Effect on Cloud Cavitation Flow around a Clark-Y Hydrofoil
16
作者 Di Peng Guoqing Chen +1 位作者 Jiale Yan Shiping Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2947-2964,共18页
Cavitation is a prevalent phenomenon within the domain of ship and ocean engineering,predominantly occurring in the tail flow fields of high-speed rotating propellers and on the surfaces of high-speed underwater vehic... Cavitation is a prevalent phenomenon within the domain of ship and ocean engineering,predominantly occurring in the tail flow fields of high-speed rotating propellers and on the surfaces of high-speed underwater vehicles.The re-entrant jet and compression wave resulting from the collapse of cavity vapour are pivotal factors contributing to cavity instability.Concurrently,these phenomena significantly modulate the evolution of cavitation flow.In this paper,numerical investigations into cloud cavitation over a Clark-Y hydrofoil were conducted,utilizing the Large Eddy Simulation(LES)turbulence model and the Volume of Fluid(VOF)method within the OpenFOAM framework.Comparative analysis of results obtained at different angles of attack is undertaken.A discernible augmentation in cavity thickness is observed concomitant with the escalation in attack angle,alongside a progressive intensification in pressure at the leading edge of the hydrofoil,contributing to the suction force.These results can serve as a fundamental point of reference for gaining a deeper comprehension of cloud cavitation dynamics. 展开更多
关键词 cloud cavitation re-entrant jet compression wave clark-Y hydrofoil
下载PDF
Blockchain-Based Certificateless Bidirectional Authenticated Searchable Encryption Scheme in Cloud Email System
17
作者 Yanzhong Sun Xiaoni Du +1 位作者 Shufen Niu Xiaodong Yang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3287-3310,共24页
Traditional email systems can only achieve one-way communication,which means only the receiver is allowed to search for emails on the email server.In this paper,we propose a blockchain-based certificateless bidirectio... Traditional email systems can only achieve one-way communication,which means only the receiver is allowed to search for emails on the email server.In this paper,we propose a blockchain-based certificateless bidirectional authenticated searchable encryption model for a cloud email system named certificateless authenticated bidirectional searchable encryption(CL-BSE)by combining the storage function of cloud server with the communication function of email server.In the new model,not only can the data receiver search for the relevant content by generating its own trapdoor,but the data owner also can retrieve the content in the same way.Meanwhile,there are dual authentication functions in our model.First,during encryption,the data owner uses the private key to authenticate their identity,ensuring that only legal owner can generate the keyword ciphertext.Second,the blockchain verifies the data owner’s identity by the received ciphertext,allowing only authorized members to store their data in the server and avoiding unnecessary storage space consumption.We obtain a formal definition of CL-BSE and formulate a specific scheme from the new system model.Then the security of the scheme is analyzed based on the formalized security model.The results demonstrate that the scheme achieves multikeyword ciphertext indistinguishability andmulti-keyword trapdoor privacy against any adversary simultaneously.In addition,performance evaluation shows that the new scheme has higher computational and communication efficiency by comparing it with some existing ones. 展开更多
关键词 cloud email system authenticated searchable encryption blockchain-based designated server test multi-trapdoor privacy multi-ciphertext indistinguishability
下载PDF
Quantum circuit-based proxy blind signatures:A novel approach and experimental evaluation on the IBM quantum cloud platform
18
作者 娄小平 昝慧茹 徐雪娇 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期247-253,共7页
This paper presents a novel approach to proxy blind signatures in the realm of quantum circuits,aiming to enhance security while safeguarding sensitive information.The main objective of this research is to introduce a... This paper presents a novel approach to proxy blind signatures in the realm of quantum circuits,aiming to enhance security while safeguarding sensitive information.The main objective of this research is to introduce a quantum proxy blind signature(QPBS)protocol that utilizes quantum logical gates and quantum measurement techniques.The QPBS protocol is constructed by the initial phase,proximal blinding message phase,remote authorization and signature phase,remote validation,and de-blinding phase.This innovative design ensures a secure mechanism for signing documents without revealing the content to the proxy signer,providing practical security authentication in a quantum environment under the assumption that the CNOT gates are securely implemented.Unlike existing approaches,our proposed QPBS protocol eliminates the need for quantum entanglement preparation,thus simplifying the implementation process.To assess the effectiveness and robustness of the QPBS protocol,we conduct comprehensive simulation studies in both ideal and noisy quantum environments on the IBM quantum cloud platform.The results demonstrate the superior performance of the QPBS algorithm,highlighting its resilience against repudiation and forgeability,which are key security concerns in the realm of proxy blind signatures.Furthermore,we have established authentic security thresholds(82.102%)in the presence of real noise,thereby emphasizing the practicality of our proposed solution. 展开更多
关键词 proxy blind signature quantum circuits quantum computation IBM quantum cloud platform
下载PDF
RESTlogic: Detecting Logic Vulnerabilities in Cloud REST APIs
19
作者 Ziqi Wang Weihan Tian Baojiang Cui 《Computers, Materials & Continua》 SCIE EI 2024年第2期1797-1820,共24页
logical testing model and resource lifecycle information,generate test cases and complete parameters,and alleviate inconsistency issues through parameter inference.Once again,we propose a method of analyzing test resu... logical testing model and resource lifecycle information,generate test cases and complete parameters,and alleviate inconsistency issues through parameter inference.Once again,we propose a method of analyzing test results using joint state codes and call stack information,which compensates for the shortcomings of traditional analysis methods.We will apply our method to testing REST services,including OpenStack,an open source cloud operating platform for experimental evaluation.We have found a series of inconsistencies,known vulnerabilities,and new unknown logical defects. 展开更多
关键词 cloud services RESTful API logic defects inconsistency issues
下载PDF
Estimating wood quality attributes from dense airborne LiDAR point clouds
20
作者 Nicolas Cattaneo Stefano Puliti +1 位作者 Carolin Fischer Rasmus Astrup 《Forest Ecosystems》 SCIE CSCD 2024年第2期226-235,共10页
Mapping individual tree quality parameters from high-density LiDAR point clouds is an important step towards improved forest inventories.We present a novel machine learning-based workflow that uses individual tree poi... Mapping individual tree quality parameters from high-density LiDAR point clouds is an important step towards improved forest inventories.We present a novel machine learning-based workflow that uses individual tree point clouds from drone laser scanning to predict wood quality indicators in standing trees.Unlike object reconstruction methods,our approach is based on simple metrics computed on vertical slices that summarize information on point distances,angles,and geometric attributes of the space between and around the points.Our models use these slice metrics as predictors and achieve high accuracy for predicting the diameter of the largest branch per log (DLBs) and stem diameter at different heights (DS) from survey-grade drone laser scans.We show that our models are also robust and accurate when tested on suboptimal versions of the data generated by reductions in the number of points or emulations of suboptimal single-tree segmentation scenarios.Our approach provides a simple,clear,and scalable solution that can be adapted to different situations both for research and more operational mapping. 展开更多
关键词 UAV laser scanning Wood quality Machine learning Point cloud metrics
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部