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Microphysical Properties of Convective Clouds in Summer over the Tibetan Plateau from SNPP/VⅡRS Satellite Data
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作者 Zhiguo YUE Xing YU +5 位作者 Guihua LIU Jin DAI Yannian ZHU Xiaohong XU Ying HUI Chuang CHEN 《气象学报:英文版》 SCIE CSCD 2019年第3期433-445,共13页
The Tibetan Plateau (TP) plays an important role in formation and development of the East Asian atmospheric circulation, climate variability, and disastrous weathers in China. Among the many topics on TP meteorology, ... The Tibetan Plateau (TP) plays an important role in formation and development of the East Asian atmospheric circulation, climate variability, and disastrous weathers in China. Among the many topics on TP meteorology, it is critical to understand the microphysical characteristics of clouds over the TP;however, observations of the cloud microphysics in this area are insufficient mainly due to sparse stations and limited cloud physical data. The Visible Infrared Imaging Radiometer Suite (VⅡRS), onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite, has an improved imaging spectroradiometer with 17 channels of 750-m moderate resolution and 5 channels of 375-m image resolution. The high-resolution instrument has an advantage for observing the small or initial convective clouds. Based on the methodologies that we proposed before for retrieving cloud microphysical properties from SNPP, an automated mapping software package named Automatic Mapping of Convective Clouds (AMCC) has been developed at the scale of satellite swath. The properties of convective clouds are retrieved by AMCC and their values are averaged over 0.33°×0.33° grids based on the SNPP/VⅡRS satellite data over the TP during the summers of 2013-17. The results show that:(1) the temperature of lifting condensation level (TLCL) at Naqu meteorological station and the cloud base temperature (Tb) retrieved from VⅡRS are linearly correlated, with a correlation coefficient of 0.87 and standard deviation (STD) of 3.0℃;(2) convective clouds over the TP have the following macro-and microphysical properties. First, the cloud base temperature (Tb) is about -5℃, the cloud base height above the ground (Hb) ranges between 1800 and 2200 m, and the cloud water content is low. Second, the cloud condensation nuclei concentration (NCCN) is between 200 and 400 mg-1 with 0.7% in maximum supersaturation (Smax);consequently, the condensation growth of water cloud droplet with less NCCN and higher Smax is fast. Third, because the precipitation initia 展开更多
关键词 Tibetan Plateau Visible Infrared Imaging RADIOMETER SUITE (VⅡRS) retrieval of CLOUD microphysical properties CONVECTIVE CLOUD CLOUD base temperature CLOUD condensation nuclei
LASG Global AGCM with a Two-moment Cloud Microphysics Scheme:Energy Balance and Cloud Radiative Forcing Characteristics 预览
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作者 Lei WANG Qing BAO +9 位作者 Wei-Chyung WANG Yimin LIU Guo-Xiong WU Linjiong ZHOU JiANDong LI Hua GONG Guokui NIAN Jinxiao LI Xiaocong WANG Bian HE 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第7期697-710,共14页
Cloud dominates influence factors of atmospheric radiation, while aerosol–cloud interactions are of vital importance in its spatiotemporal distribution. In this study, a two-moment(mass and number) cloud microphysics... Cloud dominates influence factors of atmospheric radiation, while aerosol–cloud interactions are of vital importance in its spatiotemporal distribution. In this study, a two-moment(mass and number) cloud microphysics scheme, which significantly improved the treatment of the coupled processes of aerosols and clouds, was incorporated into version 1.1 of the IAP/LASG global Finite-volume Atmospheric Model(FAMIL1.1). For illustrative purposes, the characteristics of the energy balance and cloud radiative forcing(CRF) in an AMIP-type simulation with prescribed aerosols were compared with those in observational/reanalysis data. Even within the constraints of the prescribed aerosol mass, the model simulated global mean energy balance at the top of the atmosphere(TOA) and at the Earth’s surface, as well as their seasonal variation, are in good agreement with the observational data. The maximum deviation terms lie in the surface downwelling longwave radiation and surface latent heat flux, which are 3.5 W m-2(1%) and 3 W m-2(3.5%), individually. The spatial correlations of the annual TOA net radiation flux and the net CRF between simulation and observation were around 0.97 and 0.90, respectively. A major weakness is that FAMIL1.1 predicts more liquid water content and less ice water content over most oceans. Detailed comparisons are presented for a number of regions, with a focus on the Asian monsoon region(AMR). The results indicate that FAMIL1.1 well reproduces the summer–winter contrast for both the geographical distribution of the longwave CRF and shortwave CRF over the AMR. Finally, the model bias and possible solutions, as well as further works to develop FAMIL1.1 are discussed. 展开更多
关键词 two-moment CLOUD MICROPHYSICS SCHEME aerosol–cloud interactions energy balance CLOUD radiative forcing Asian monsoon region
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Cloud service selection using cloud service brokers: approaches and challenges
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作者 Meysam VAKILI Neda JAHANGIRI Mohsen SHARIFI 《中国计算机科学前沿:英文版》 SCIE EI CSCD 2019年第3期599-617,共19页
Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews ... Cloud computing users are faced with a wide variety of services to choose from. Consequently, a number of cloud service brokers (CSBs) have emerged to help users in their service selection process. This paper reviews the recent approaches that have been introduced and used for cloud service brokerage and discusses their challenges accordingly. We propose a set of attributes for a CSB to be considered effective. DifFerent CSBs' approaches are classified as either single service or multiple service models. The CSBs are then assessed, analyzed, and compared with respect to the proposed set of attributes. Based on our studies, CSBs with multiple service models that support more of the proposed effective CSB attributes have wider application in cloud computing environments. 展开更多
关键词 CLOUD SERVICE BROKER (CSB) CLOUD SERVICE SELECTION CLOUD computing quality of SERVICE (QoS)
基于卫星遥感的祁连山及甘肃中部地区云宏观特征
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作者 宋琦明 张武 +4 位作者 苏亚乔 陈艳 杨昆 赵桂清 曹刚 《干旱区研究》 CSCD 北大核心 2019年第3期712-722,共11页
利用2007—2010年Cloud Sat和CALIPSO卫星遥感资料以及中国国家气象信息中心(CMDC)提供的地面降水资料(1996—2016年),对祁连山区、甘肃中部及石羊河流域的不同云类型宏观特征进行了分析。结果表明:各研究区域总云分数的季节变化较一致... 利用2007—2010年Cloud Sat和CALIPSO卫星遥感资料以及中国国家气象信息中心(CMDC)提供的地面降水资料(1996—2016年),对祁连山区、甘肃中部及石羊河流域的不同云类型宏观特征进行了分析。结果表明:各研究区域总云分数的季节变化较一致,较大值出现在春夏季,均超过70%。总云分数的高值区主要集中在祁连山南坡,与降水量高值区分布一致。积状云云分数最大值出现在夏季,积状云降水频率高于层状云。云层以单层云为主,云厚度均超过2.0 km,春季甘肃中部的单层云厚度最大达3.0 km;2层云夹层比3层云的夹层厚度要厚。产生降水的云中积状云和单层云的发生频率较高。各区域云频率随高度分布趋势大致相同,层状云出现的高度在距地表0.5 km到12.0 km,云频率峰值均在高度6.0 km左右出现;积状云云频率随高度分布较层状云明显偏低,峰值出现在1.5km左右高度。 展开更多
关键词 降水 CLOUD SAT CALIPSO 祁连山 甘肃
Comparisons of AGRI/FY-4A Cloud Fraction and Cloud Top Pressure with MODIS/Terra Measurements over East Asia
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作者 Tao WANG Jiali LUO +3 位作者 Jinglin LIANG Baojian WANG Wenshou TIAN Xiaoyan CHEN 《气象学报:英文版》 SCIE CSCD 2019年第4期705-719,共15页
Fengyun-4 A(FY-4 A),the second generation of China’s geostationary meteorological satellite,provides high spatiotemporal resolution cloud products over East Asia.In this study,cloud fraction(CFR)and cloud top pressur... Fengyun-4 A(FY-4 A),the second generation of China’s geostationary meteorological satellite,provides high spatiotemporal resolution cloud products over East Asia.In this study,cloud fraction(CFR)and cloud top pressure(CTP)products in August 2017 derived from the Advanced Geosynchronous Radiation Imager(AGRI)aboard FY-4 A(AGRI/FY-4 A)are retrospectively compared with those from the Moderate Resolution Imaging Spectroradiometer(MODIS)aboard Terra(MODIS/Terra)over East Asia.To avoid possible errors in the comparison caused by the lower temporal coverage of MODIS/Terra products compared to that of AGRI/FY-4 A over the same region and to account for time lags between observations of the two instruments,we construct datasets of AGRI/FY-4 A CFR and CTP to match those of MODIS/Terra in each scan over East Asia in August 2017.Results show that the CFR and CTP datasets of the two instruments generally agree well,with the linear correlation coefficients(R)between CFR(CTP)data of 0.83(0.80)regardless of time lags.Though longer time lags contribute to the worse consistency between CFR(CTP)data derived from observations of the two instruments in most cases,large CFR/CTP discrepancies do not always match with long time lags.Large CFR discrepancies appear in the vicinity of the Tibetan Plateau(TP;28°–45°N,75°–105°E).These differences in the cloud detection by the two instruments largely occur when MODIS/Terra detects clear-sky while AGRI/FY-4 A detects higher values of CFR,and this accounts for 61%of the CFR discrepancy greater than 50%near the TP.In the case of CTP,the largest discrepancies appear in the eastern Iranian Plateau(IP;25°–45°N,60°–80°E),where there are some samples with long time lags(20–35 min)and fewer daily data samples are available for computing monthly means compared to other regions since there are many clearsky data samples there during the study period. 展开更多
关键词 AGRI/FJM/ MODIS/7erra cloud fraction cloud top pressure
Stream-computing of High Accuracy On-board Real-time Cloud Detection for High Resolution Optical Satellite Imagery 预览
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作者 Mi WANG Zhiqi ZHANG +2 位作者 Zhipeng DONG Shuying JIN Hongbo SU 《测绘学报(英文版)》 2019年第2期50-59,共10页
This paper focuses on the time efficiency for machine vision and intelligent photogrammetry, especially high accuracy on-board real-time cloud detection method. With the development of technology, the data acquisition... This paper focuses on the time efficiency for machine vision and intelligent photogrammetry, especially high accuracy on-board real-time cloud detection method. With the development of technology, the data acquisition ability is growing continuously and the volume of raw data is increasing explosively. Meanwhile, because of the higher requirement of data accuracy, the computation load is also becoming heavier. This situation makes time efficiency extremely important. Moreover, the cloud cover rate of optical satellite imagery is up to approximately 50%, which is seriously restricting the applications of on-board intelligent photogrammetry services. To meet the on-board cloud detection requirements and offer valid input data to subsequent processing, this paper presents a stream-computing of high accuracy on-board real-time cloud detection solution which follows the “bottom-up” understanding strategy of machine vision and uses multiple embedded GPU with significant potential to be applied on-board. Without external memory, the data parallel pipeline system based on multiple processing modules of this solution could afford the “stream-in, processing, stream-out” real-time stream computing. In experiments, images of GF-2 satellite are used to validate the accuracy and performance of this approach, and the experimental results show that this solution could not only bring up cloud detection accuracy, but also match the on-board real-time processing requirements. 展开更多
关键词 machine vision intelligent PHOTOGRAMMETRY CLOUD detection STREAM COMPUTING ON-BOARD REAL-TIME processing
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Performance of CAMS-CSM in Simulating the Shortwave Cloud Radiative Effect over Global Stratus Cloud Regions:Baseline Evaluation and Sensitivity Test
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作者 Yihui ZHOU Yi ZHANG +2 位作者 Xinyao RONG Jian LI Rucong YU 《气象学报:英文版》 SCIE CSCD 2019年第4期651-665,共15页
The ability of climate models to correctly reproduce clouds and the radiative effects of clouds is vitally important in climate simulations and projections.In this study,simulations of the shortwave cloud radiative ef... The ability of climate models to correctly reproduce clouds and the radiative effects of clouds is vitally important in climate simulations and projections.In this study,simulations of the shortwave cloud radiative effect(SWCRE)using the Chinese Academy of Meteorological Sciences Climate System Model(CAMS-CSM)are evaluated.The relationships between SWCRE and dynamic–thermodynamic regimes are examined to understand whether the model can simulate realistic processes that are responsible for the generation and maintenance of stratus clouds.Over eastern China,CAMS-CSM well simulates the SWCRE climatological state and stratus cloud distribution.The model captures the strong dependence of SWCRE on the dynamic conditions.Over the marine boundary layer regions,the simulated SWCRE magnitude is weaker than that in the observations due to the lack of low-level stratus clouds in the model.The model fails to simulate the close relationship between SWCRE and local stability over these regions.A sensitivity numerical experiment using a specifically designed parameterization scheme for the stratocumulus cloud cover confirms this assertion.Parameterization schemes that directly depict the relationship between the stratus cloud amount and stability are beneficial for improving the model performance. 展开更多
关键词 Chinese Academy of Meteorological Sciences Climate System Model (CAMS-CSM) shortwave cloudradiative effect (SWCRE) stratus cloud model errors
Splitting and Merging Based Multi-model Fitting for Point Cloud Segmentation 预览
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作者 Liangpei ZHANG Yun ZHANG +2 位作者 Zhenzhong CHEN Peipei XIAO Bin LUO 《测绘学报(英文版)》 2019年第2期78-89,共12页
This paper deals with the massive point cloud segmentation processing technology on the basis of machine vision, which is the second essential factor for the intelligent data processing of three dimensional conformati... This paper deals with the massive point cloud segmentation processing technology on the basis of machine vision, which is the second essential factor for the intelligent data processing of three dimensional conformation in digital photogrammetry. In this paper, multi-model fitting method is used to segment the point cloud according to the spatial distribution and spatial geometric structure of point clouds by fitting the point cloud into different geometric primitives models. Because point cloud usually possesses large amount of 3D points, which are uneven distributed over various complex structures, this paper proposes a point cloud segmentation method based on multi-model fitting. Firstly, the pre-segmentation of point cloud is conducted by using the clustering method based on density distribution. And then the follow fitting and segmentation are carried out by using the multi-model fitting method based on split and merging. For the plane and the arc surface, this paper uses different fitting methods, and finally realizing the indoor dense point cloud segmentation. The experimental results show that this method can achieve the automatic segmentation of the point cloud without setting the number of models in advance. Compared with the existing point cloud segmentation methods, this method has obvious advantages in segmentation effect and time cost, and can achieve higher segmentation accuracy. After processed by method proposed in this paper, the point cloud even with large-scale and complex structures can often be segmented into 3D geometric elements with finer and accurate model parameters, which can give rise to an accurate 3D conformation. 展开更多
关键词 machine vision 3D CONFORMATION point cloud SEGMENTATION SPLITTING and MERGING MULTI-MODEL FITTING
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Cloud Radiative Feedbacks during the ENSO Cycle Simulated by CAMS-CSM
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作者 Lin CHEN Lijuan HUA +5 位作者 Xinyao RONG Jian LI Lu WANG Guo ZHANG Ming SUN Zi'an GE 《气象学报:英文版》 SCIE CSCD 2019年第4期666-677,共12页
This study evaluated the simulated cloud radiative feedbacks(CRF)during the El Ni?o–Southern Oscillation(ENSO)cycle in the latest version of the Chinese Academy of Meteorological Sciences climate system model(CAMS-CS... This study evaluated the simulated cloud radiative feedbacks(CRF)during the El Ni?o–Southern Oscillation(ENSO)cycle in the latest version of the Chinese Academy of Meteorological Sciences climate system model(CAMS-CSM).We conducted two experimental model simulations:the Atmospheric Model Intercomparison Project(AMIP),forced by the observed sea surface temperature(SST);and the preindustrial control(PIcontrol),a coupled run without flux correction.We found that both the experiments generally reproduced the observed features of the shortwave and longwave cloud radiative forcing(SWCRF and LWCRF)feedbacks.The AMIP run exhibited better simulation performance in the magnitude and spatial distribution than the PIcontrol run.Furthermore,the simulation biases in SWCRF and LWCRF feedbacks were linked to the biases in the representation of the corresponding total cloud cover and precipitation feedbacks.It is interesting to further find that the simulation bias originating in the atmospheric component was amplified in the PIcontrol run,indicating that the coupling aggravated the simulation bias.Since the PIcontrol run exhibited an apparent mean SST cold bias over the cold tongue,the precipitation response to the SST anomaly(SSTA)changes during the ENSO cycle occurred towards the relatively warmer western equatorial Pacific.Thus,the corresponding cloud cover and CRF shifted westward and showed a weaker magnitude in the PIcontrol run versus observational data.In contrast,the AMIP run was forced by the observational SST,hence representing a more realistic CRF.Our results demonstrate the challenges of simulating CRF in coupled models.This study also underscores the necessity of realistically representing the climatological mean state when simulating CRF during the ENSO cycle. 展开更多
关键词 ENSO CAMS climate system model cloud radiative feedbacks ENSO cycle
LCCFS: a lightweight distributed file system for cloud computing without journaling and metadata services
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作者 Li WANG Jingling XUE +2 位作者 Xiangke LIAO Yunchuan WEN Min CHEN 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第7期142-155,共14页
The major usage of a file system integrated with a cloud computing platform is to provide the storage for VM(virtual machine) instances. Distributed file systems, especially those implemented on top of object storage ... The major usage of a file system integrated with a cloud computing platform is to provide the storage for VM(virtual machine) instances. Distributed file systems, especially those implemented on top of object storage have many potential advantages over traditional local file systems for VM instance storage. In this paper, we make an investigation in the requirements imposed on a file system in cloud computing scenario,and claim that the implementation of a file system for VM instance storage could be reasonably simplified. We demonstrate that on top of an object storage with simple object-granularity transaction support, a lightweight distributed file system, which requires neither journaling nor dedicated metadata services, can be developed for cloud computing. We have implemented such a distributed file system, called LCCFS(lightweight cloud computing file system), based on the RADOS(reliable autonomic distributed object storage) object storage.Our experimental results show that for the main workloads in cloud computing, LCCFS achieves almost the same or slightly higher performance than CephFS(ceph filesystem), another published distributed file system based on RADOS. Compared to CephFS, LCCFS has only one tenth of its LOCs(lines of code). This theoretical simplicity makes it easy to implement LCCFS correctly and stably by avoiding the sheer design and implementation complexity behind CephFS, thereby making LCCFS a promising candidate in the cloud computing production environment. 展开更多
关键词 cloud COMPUTING distributed file system journaling METADATA service GARBAGE COLLECTION
Secure Inverted Index Based Search over Encrypted Cloud Data with User Access Rights Management
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作者 Fateh Boucenna Omar Nouali +1 位作者 Samir Kechid M.Tahar Kechadi 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第1期133-154,共22页
Cloud computing is a technology that provides users with a large storage space and an enormous computing power.However,the outsourced data are often sensitive and confidential,and hence must be encrypted before being ... Cloud computing is a technology that provides users with a large storage space and an enormous computing power.However,the outsourced data are often sensitive and confidential,and hence must be encrypted before being outsourced.Consequently,classical search approaches have become obsolete and new approaches that are compatible with encrypted data have become a necessity.For privacy reasons,most of these approaches are based on the vector model which is a time consuming process since the entire index must be loaded and exploited during the search process given that the query vector must be compared with each document vector.To solve this problem,we propose a new method for constructing a secure inverted index using two key techniques,homomorphic encryption and the dummy documents technique.However,1)homomorphic encryption generates very large ciphertexts which are thousands of times larger than their corresponding plaintexts,and 2)the dummy documents technique that enhances the index security produces lots of false positives in the search results.The proposed approach exploits the advantages of these two techniques by proposing two methods called the compressed table of encrypted scores and the double score formula.Moreover,we exploit a second secure inverted index in order to manage the users'access rights to the data.Finally,in order to validate our approach,we performed an experimental study using a data collection of one million documents.The experiments show that our approach is many times faster than any other approach based on the vector model. 展开更多
关键词 searchable ENCRYPTION cloud COMPUTING homomorphic ENCRYPTION attributeqbased ENCRYPTION INVERTED index
On Maximum Elastic Scheduling in Cloud-Based Data Center Networks for Virtual Machines with the Hose Model
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作者 Shuai-Bing Lu Jie Wu +1 位作者 Huan-Yang Zheng Zhi-Yi Fang 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第1期185-206,共22页
With the growing popularity of cloud-based data center networks (DCNs),task resource allocation has become more and more important to the efficient use of resource in DCNs.This paper considers provisioning the maximum... With the growing popularity of cloud-based data center networks (DCNs),task resource allocation has become more and more important to the efficient use of resource in DCNs.This paper considers provisioning the maximum admissible load (MAL)of virtual machines (VMs)in physical machines (PMs)with underlying tree-structured DCNs using the hose model for communication.The limitation of static load distribution is that it assigns tasks to nodes in a once-and-for-all manner,and thus requires a priori knowledge of program behavior.To avoid load redistribution during runtime when the load grows,we introduce maximum elasticity scheduling,which has the maximum growth potential subject to the node and link capacities.This paper aims to find the schedule with the maximum elasticity across nodes and links.We first propose a distributed linear solution based on message passing,and we discuss several properties and extensions of the model.Based on the assumptions and conclusions,we extend it to the multiple paths case with a fat tree DCN,and discuss the optimal solution for computing the MAL with both computation and communication constraints.After that,we present the provision scheme with the maximum elasticity for the VMs,which comes with provable optimality guarantee for a fixed flow scheduling strategy in a fat tree DCN.We conduct the evaluations on our testbed and present various simulation results by comparing the proposed maximum elastic scheduling schemes with other methods.Extensive simulations validate the effectiveness of the proposed policies,and the results are shown from different perspectives to provide solutions based on our research. 展开更多
关键词 data center network (DCN) CLOUD DISTRIBUTED algorithm ELASTICITY HOSE model optimization
Cloud Classification and Distribution of Cloud Types in Beijing Using Ka-Band Radar Data 预览
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作者 Juan HUO Yongheng BI +1 位作者 Daren LU Shu DUAN 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第8期793-803,共11页
A cloud clustering and classification algorithm is developed for a ground-based Ka-band radar system in the vertically pointing mode. Cloud profiles are grouped based on the combination of a time–height clustering me... A cloud clustering and classification algorithm is developed for a ground-based Ka-band radar system in the vertically pointing mode. Cloud profiles are grouped based on the combination of a time–height clustering method and the k-means clustering method. The cloud classification algorithm, developed using a fuzzy logic method, uses nine physical parameters to classify clouds into nine types: cirrostratus, cirrocumulus, altocumulus, altostratus, stratus, stratocumulus, nimbostratus,cumulus or cumulonimbus. The performance of the clustering and classification algorithm is presented by comparison with all-sky images taken from January to June 2014. Overall, 92% of the cloud profiles are clustered successfully and the agreement in classification between the radar system and the all-sky imager is 87%. The distribution of cloud types in Beijing from January 2014 to December 2017 is studied based on the clustering and classification algorithm. The statistics show that cirrostratus clouds have the highest occurrence frequency(24%) among the nine cloud types. High-level clouds have the maximum occurrence frequency and low-level clouds the minimum occurrence frequency. 展开更多
关键词 CLOUDS CLUSTERING ALGORITHM classification ALGORITHM RADAR CLOUD type
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基于“大物移云”技术的医养结合养老模式研究 预览
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作者 邢丹 姚俊明 邵婷婷 《医学信息学杂志》 CAS 2019年第1期18-22,共5页
阐述国内外养老模式及医养结合存在的问题,提出采用“大物移云”技术,根据老年人健康情况和需求构建医养结合养老模式,介绍总体框架和主要内容,建设老年人电子健康档案和信息平台,实现疾病监测、医疗诊断、康复及护理功能。
关键词 医养结合 养老模式 大数据 物联网 移动互联网
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Research on the Big Data Cloud Computing Based on the Network Data Mining 预览
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作者 ZHANG Haiyang ZHANG Zhiwei 《国际英语教育研究:英文版》 2019年第2期72-74,共3页
The big data cloud computing is a new computing mode,which integrates the distributed processing,the parallel processing,the network computing,the virtualization technology,the load balancing and other network technol... The big data cloud computing is a new computing mode,which integrates the distributed processing,the parallel processing,the network computing,the virtualization technology,the load balancing and other network technologies.Under the operation of the big data cloud computing system,the computing resources can be distributed in a resource pool composed of a large number of the computers,allowing users to connect with the remote computer systems according to their own data information needs. 展开更多
关键词 NETWORK DATA mining BIG DATA cloud COMPUTING technology processing
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The Optimization of Manufacturing Resources Allocation Considering the Geographical Distribution 预览
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作者 Ceyuan Liang Lijun He Guangyu Zhu 《哈尔滨工业大学学报:英文版》 EI CAS 2019年第4期78-88,共11页
From the perspective of the geographical distribution, considering production fare, supply chain information and quality rating of the manufacturing resource(MR), a manufacturing resource allocation(MRA) model conside... From the perspective of the geographical distribution, considering production fare, supply chain information and quality rating of the manufacturing resource(MR), a manufacturing resource allocation(MRA) model considering the geographical distribution in cloud manufacturing(CM) environment is built. The model includes two stages, preliminary selection stage and optimal selection stage. The membership function is used to select MRs from cloud resource pool(CRP) in the first stage, and then the candidate resource pool is built. In the optimal selection stage, a multi-objective optimization algorithm, particle swarm optimization(PSO) based on the method of relative entropy of fuzzy sets(REFS_PSO), is used to select optimal MRs from the candidate resource pool, and an optimal manufacturing resource supply chain is obtained at last. To verify the performance of REFS_PSO, NSGA-Ⅱ and PSO based on random weighting(RW_PSO) are selected as the comparison algorithms. They all are used to select optimal MRs at the second stage. The experimental results show solution obtained by REFS_PSO is the best. The model and the method proposed are appropriate for MRA in CM. 展开更多
关键词 cloud manufacturing RESOURCE OPTIMIZATION ALLOCATION Fuzzy Sets RELATIVE ENTROPY many-objective OPTIMIZATION supply chain
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The Extra-Area Effect in 71 Cloud Seeding Operations during Winters of 2008-14 over Jiangxi Province, East China
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作者 Weijian WANG Zhanyu YAO +5 位作者 Jianping GUO Chao TAN Shuo JIA Wenhui ZHAO Pei ZHANG Liangshu GAO 《气象学报:英文版》 SCIE CSCD 2019年第3期528-539,共12页
Effects of weather modification operations on precipitation in target areas have been widely reported, but little is specifically known about the downwind (extra-area) effects in China. We estimated the extra-area eff... Effects of weather modification operations on precipitation in target areas have been widely reported, but little is specifically known about the downwind (extra-area) effects in China. We estimated the extra-area effect of an operational winter (November-February) aircraft cloud-seeding project in northern Jiangxi Province in eastern China by using a revised historical target/control regression analysis method based on the precipitation data in winter. The results showed that the overall seasonal average rainfall at the downwind stations increased by 21.67%(p=0.0013). This enhancement effect was detected as far as 120 km away from the target area. Physical testing was used to compare the cloud characteristics before and after seeding on 29 November 2014. A posteriori analysis with respect to the characteristics of cloud units derived from operational weather radar data in Jiangxi was performed by tracking cloud units. Radar features in the target unit were enhanced relative to the control unit for more than two hours after the operational cloud seeding, which is indicative of the extra-area seeding effect. The findings could be used to help relieve water shortages in China. 展开更多
关键词 cloud SEEDING extra-area effects RADAR derived RAINFALL characteristics
Experimental and numerical studies on the cavitation over flat hydrofoils with and without obstacle 预览
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作者 Ling-xin Zhang Ming Chen +1 位作者 Jian Deng Xue-ming Shao 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第4期708-716,共9页
To control the shedding of cavitation, an obstacle is placed on the surface of a flat hydrofoil. Both experimental and numerical studies are carried out. Images of cavitation evolution are recorded by a high-speed cam... To control the shedding of cavitation, an obstacle is placed on the surface of a flat hydrofoil. Both experimental and numerical studies are carried out. Images of cavitation evolution are recorded by a high-speed camera. 3-D simulations are performed to investigate the cavitating flows around the hydrofoil. The results show that the re-entrant jet plays an important role during the process of cavitation shedding. A kind of U-type shedding is identified during the evolution of the cloud cavitation. The length of the cavity is apparently reduced due to the placement of the obstacle. It is interesting to find that the cavitation shedding changes from the large-scale mode to a small-scale mode, as an obstacle is placed on the hydrofoil surface. As we can observe from both experimental and numerical results, the small-scale cavitation shedding dominates the cavitating flow dynamics, we thereby conclude that the placement of an obstacle is favorable for the inhibition of cavitation shedding. 展开更多
关键词 CLOUD CAVITATION OBSTACLE RE-ENTRANT JET
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MapReduce rationality verification based on object Petri net 预览
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作者 DING Zeliu GUO Deke +1 位作者 CHEN Xi CHEN Jin 《系统工程与电子技术:英文版》 SCIE EI CSCD 2019年第5期861-874,共14页
As a powerful distributed data processing mechanism,MapReduce supports abundant parallel applications that process massive data on computer clusters.To process the massive data efficiently and correctly,a rational des... As a powerful distributed data processing mechanism,MapReduce supports abundant parallel applications that process massive data on computer clusters.To process the massive data efficiently and correctly,a rational design for the MapReduce procedure is desired.An irrational MapReduce procedure can cause great waste of computing resources and even paralyze the execution system.With the wide application of MapReduce,the unavoidable drawback of irrational MapReduce procedures becomes increasingly serious.To solve this problem,a method for verifying the rationality of a MapReduce procedure before executing it on a computer cluster is proposed.This method constructs the rationality criteria for MapReduce,and then studies an automatic approach for modelling MapReduce with an executable model object Petri net(OPN).Finally,the approaches for automatically identifying the rationality criteria by analyzing the consequence of model execution is developed.The results from extensive case studies demonstrate that the proposed method is feasible and effective. 展开更多
关键词 MAPREDUCE rationality verification cloud computingframework
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Research on the big data feature mining technology based on the cloud computing 预览
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作者 WANG Yun 《国际英语教育研究:英文版》 2019年第3期52-54,共3页
The cloud computing platform has the functions of efficiently allocating the dynamic resources, generating the dynamic computing and storage according to the user requests, and providing the good platform for the big ... The cloud computing platform has the functions of efficiently allocating the dynamic resources, generating the dynamic computing and storage according to the user requests, and providing the good platform for the big data feature analysis and mining. The big data feature mining in the cloud computing environment is an effective method for the elficient application of the massive data in the information age. In the process of the big data mining, the method o f the big data feature mining based on the gradient sampling has the poor logicality. It only mines the big data features from a single-level perspective, which reduces the precision of the big data feature mining. 展开更多
关键词 CLOUD COMPUTING BIG data features MINING technology model method
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