检索结果-南通市图书馆

The Impact of Assimilating Radar-estimated Rain Rates on Simulation of Precipitation in the 17-18 July 1996 Chicago Floods

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2010年第2期27卷 195-210页

作者： Xingbao WANG M. K. yau B. NAGARAJAN Luc FILLION Deptartment of Atmospheric and Oceanic Sciences McGiU University Montreal Canada Recherche en Prevision Numerique Environment Canada Dorval Montreal Canada

Rainfall prediction remains one of the most challenging problems in weather forecasting. In order to improve high-resolution quantitative precipitation forecasts （QPF）, a new procedure for assimilating rainfall rate derived from radar composite reflectivity has been proposed and tested in a numerical simulation of the Chicago floods of 17–18 July 1996. The methodology is based on the one-dimensional variation scheme （1DVAR） assimilation approach introduced by Fillion and Errico but applied here using the Kain-Fritsch convective parameterization scheme （KF CPS）. The novel feature of this work is the continuous assimilation of radar estimated rain rate over a three hour period, rather than a single assimilation at the initial （analysis） time. Most of the characteristics of this precipitation event, including the propagation, regeneration of mesoscale convective systems, the frontal boundary across the Midwest and the evolution of the low-level jet are better captured in the simulation as the radar-estimated precipitation rate is assimilated. The results indicate that precipitation assimilation during the early stage can improve the simulated mesoscale feature of the convection system and shorten the spin-up time significantly. Comparison of precipitation forecasts between the experiments with and without the 1DVAR indicates that the 1DVAR scheme has a positive impact on the QPF up to 36 hours in terms of the bias and bias equalized threat scores.

关键词： quantitative precipitation forecasts 1DVAR data assimilation

Relevant Visual Semantic Context-Aware Attention-Based Dialog

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第8期76卷 2337-2354页

作者： Eugene Tan Boon Hong Yung-Wey Chong Tat-Chee Wan Kok-Lim Alvin yau National Advanced IPv6 Centre Universiti Sains MalaysiaPenangMalaysia Lee Kong Chian Faculty of Engineering and Science(LKCFES) Universiti Tunku Abdul RahmanSungai LongSelangorMalaysia

The existing dataset for visual dialog comprises multiple rounds of questions and a diverse range of image ***,it faces challenges in overcoming visual semantic limitations,particularly in obtaining sufficient context from visual and textual aspects of *** paper proposes a new visual dialog dataset called Diverse History-Dialog(DS-Dialog)to address the visual semantic limitations faced by the existing ***-Dialog groups relevant histories based on their respective Microsoft Common Objects in Context(MSCOCO)image categories and consolidates them for each ***,each MSCOCO image category consists of top relevant histories extracted based on their semantic relationships between the original image caption and historical *** relevant histories are consolidated for each image,and DS-Dialog enhances the current dataset by adding new context-aware relevant history to provide more visual semantic context for each *** new dataset is generated through several stages,including image semantic feature extraction,keyphrase extraction,relevant question extraction,and relevant history dialog *** DS-Dialog dataset contains about 2.6 million question-answer pairs,where 1.3 million pairs correspond to existing VisDial’s question-answer pairs,and the remaining 1.3 million pairs include a maximum of 5 image features for each VisDial image,with each image comprising 10-round relevant question-answer ***,a novel adaptive relevant history selection is proposed to resolve missing visual semantic information for each ***-Dialog is used to benchmark the performance of previous visual dialog models and achieves better performance than previous ***,the proposed DSDialog model achieves an 8% higher mean reciprocal rank(MRR),11% higher R@1%,6% higher R@5%,5% higher R@10%,and 8% higher normalized discounted cumulative gain(NDCG)compared to ***-Dialog also achieves approximately 1 point improvement o

关键词： Visual dialog context-aware relevant history computer vision natural language processing

Variational Quality Control of Non-Gaussian Innovations in the GRAPES m3DVAR System: Mass Field Evaluation of Assimilation Experiments

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

Advances in Atmospheric Sciences 2021年第9期38卷 1510-1524页

作者： Jie HE Xulin MA Xuyang GE Juanjuan LIU Wei CHENG Man-yau CHAN Ziniu XIAO Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory of Meteorological DisasterNanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Beijing Institute of Applied Meteorology Beijing 100029China Department of Meteorology and Atmospheric Science and Center for Advanced Data Assimilation and Predictability TechniquesThe Pennsylvania State UniversityUniversity ParkPA 16801USA

The existence of outliers can seriously influence the analysis of variational data *** control allows us to effectively eliminate or absorb these outliers to produce better analysis *** particular,variational quality control(VarQC) can process gray zone outliers and is thus broadly used in variational data assimilation *** this study,governing equations are derived for two VarQC algorithms that utilize different contaminated Gaussian distributions(CGDs): Gaussian plus flat distribution and Huber norm *** such,these VarQC algorithms can handle outliers that have non-Gaussian ***,these VarQC algorithms are implemented in the Global/Regional Assimilation and PrEdiction System(GRAPES) model-level three-dimensional variational data assimilation(m3 DVAR) *** using artificial observations indicate that the VarQC method using the Huber distribution has stronger robustness for including outliers to improve posterior analysis than the VarQC method using the Gaussian plus flat ***,real observation experiments show that the distribution of observation analysis weights conform well with theory,indicating that the application of VarQC is effective in the GRAPES m3 DVAR *** case study and longperiod data assimilation experiments show that the spatial distribution and amplitude of the observation analysis weights are related to the analysis increments of the mass field(geopotential height and temperature).Compared to the control experiment,VarQC experiments have noticeably better posterior mass ***,the VarQC method using the Huber distribution is superior to the VarQC method using the Gaussian plus flat distribution,especially at the middle and lower levels.

关键词： variational quality control non-Gaussian distribution innovation outlier data assimilation

通过自适应随机数据包标记实现实时IP回溯(英文)

在线全文

学校读者我要写书评

暂无评论

软件学报 2003年第5期14卷 1005-1010页

作者：梁丰赵新建 David yau 浙江工业大学浙江省光纤通信技术重点实验室浙江杭州310014 普度大学计算机科学系

随机数据包标记(PPM)是对拒绝服务攻击进行IP回溯的一种实用而有效的方法.提供了一种自适应的PPM算法:一个路由器按一个与路过的数据包已传输距离自适应的概率标记该数据包,从而被攻击者可以以最短的收敛时间重构一个攻击路径.通过一... 详细信息

随机数据包标记(PPM)是对拒绝服务攻击进行IP回溯的一种实用而有效的方法.提供了一种自适应的PPM算法:一个路由器按一个与路过的数据包已传输距离自适应的概率标记该数据包,从而被攻击者可以以最短的收敛时间重构一个攻击路径.通过一个新的称为标注片段编码的IP重载方案,实现了实时的重构,从而能同时回溯数千条路径.与以前的PPM方案相比,收敛时间减少了50%,同时大大减少了重构计算量和伪证性.

关键词：网络安全分布拒绝服务 IP回溯自适应随机数据包标记计算机网络

An Open-Source System for In Planta Gene Stacking by Bxbl and Cre Recombinases

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2014年第12期7卷 1756-1765页

作者： Lili Hou Yuan-Yeu yau Junjie Wei Zhiguo Han Zhicheng Dong David W. Ow Plant Gene Engineering Center South China Agricultural Plant Molecular Analysis and Genetic Improvement Key Laboratory SouthChina Botanical Garden Chinese Academy of Sciences 723 Xingke Road Guangzhou 510650 China University of Chinese Academy of Sciences 19 Yuquan Road Beijing 100049 China Former Affiliation Plant Gene Expression Center USDA-ARS & Plant & Microbial Biology University of California-Berkeley 800Buchanan St. Albany CA 94710 USA

The rapid development of crops with multiple transgenic traits arouses the need for an efficient system for creating stacked cultivars. Most major crops rely on classical breeding to introgress the transgene from a laboratory variety to the numerous cultivars adapted to different growing regions. Even with vegetative propagated crops, genetic crosses are conducted during varietal improvement prior to vegetative cloning. The probability to assort the ＇x＇ number of transgenic loci into a single genome may seem trivial, （~）x for a diploid species, but given the ＇y＇ number of other nontransgenic traits that breeders also need to assemble into the same genome, the （~）~＊y probability for a ＇breeding stack＇ could quickly make the line conversion process unmanageable. Adding new transgenes onto existing transgenic varieties without creating a new segregating locus would require site-specific integration of new DNA at the existing transgenic locus. Here, we tested a recombinase-mediated gene-stacking scheme in tobacco. Sequential site-specific inte- gration was mediated by the mycobacteriophage Bxbl integrase-catalyzed recombination between attP and attB sites. Transgenic DNA no longer needed after integration was excised by Cre recombinase-mediated recombination of Iox sites. Site-specific integration occurred in -10% of the integration events, with half of those events usable as substrates for a next round of gene stacking. Among the site-specific integrants, however, a third experienced gene silencing. Overall, precise structure and reproducible expression of the sequentially added triple traits were obtained at an overall rate of -3% of the transformed clones--a workable frequency for the development of commercial cultivars. Moreover, since nei- ther the Bxbl-att nor the Cre-lox system is under patent, there is freedom to operate,

关键词： transgenesis site-specific recombination integrase gene targeting transgene expression.

Temperature distribution study during the friction stir welding process of Al2024-T3 aluminum alloy

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

International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 779-787页

作者： Y.H.yau A.Hussain R.K.Lalwani H.K.Chan N.Hakimi Department of Mechanical Engineering University of Malaya50603 KLMalaysia

Heat flux characteristics are critical to good quality welding obtained in the important engineering alloy A12024- T3 by the friction stir welding （FSW） process. In the present study, thermocouples in three different configurations were amxed on the welding samples to measure the temperatures： in the first configuration, four thermocouples were placed at equivalent positions along one side of the welding direction; the second configuration involved two equivalent thermocouple locations on either side of the welding path; while the third configuration had all the thermocouples on one side of the layout but with unequal gaps from the welding line. A three-dimensional, non-linear ANSYS computational model, based on an approach applied to A12024-T3 for the first time, was used to simulate the welding temperature profiles obtained experimentally. The experimental thermal profiles on the whole were found to be in agreement with those calculated by the ANSYS model. The broad agreement between the two kinds of profiles validates the basis for derivation of the simulation model and provides an approach for the FSW simulation in A12024-T3 and is potentially more useful than models derived previously.

关键词： aluminum alloys friction stir welding welds temperature distribution

中国西部5城市中老年人血清25羟基维生素D与握力的相关性

在线全文

学校读者我要写书评

暂无评论

北京大学学报（医学版） 2024年第3期56卷 448-455页

作者：靖婷江华李婷申倩倩叶兰曾银丹梁文欣冯罡司徒文佑张玉梅北京大学公共卫生学院营养与食品卫生学系北京100191 北京大学护理学院北京100191 国家乳业技术创新中心呼和浩特010110

目的:探究中国西部5城市中老年人血清25羟基维生素D[25-hydroxyvitamin D,25(OH)D]与握力的相关性。方法:基于2023年2—7月在中国西部5个城市开展的横断面调查数据,通过问卷收集中老年人的相关人口学特征,通过体格检查记录握力,采集空... 详细信息

目的:探究中国西部5城市中老年人血清25羟基维生素D[25-hydroxyvitamin D,25(OH)D]与握力的相关性。方法:基于2023年2—7月在中国西部5个城市开展的横断面调查数据,通过问卷收集中老年人的相关人口学特征,通过体格检查记录握力,采集空腹血液样本分离血清并使用高效液相色谱串联质谱法测定血清25(OH)D浓度,使用卡方检验进行组间比较,使用Logistic回归分析西部5城市中老年人血清25(OH)D与握力的相关性。结果:我国西部5城市中老年人维生素D的缺乏率和不足率分别为52.9%和34.5%[维生素D缺乏定义为血清25(OH)D总浓度<20μg/L,维生素D不足定义为血清25(OH)D总浓度为20~30μg/L],高龄、女性、采样季节在冬季的中老年人血清25(OH)D水平更低(P<0.05)。25.3%的中老年人发生了握力减退,65~80岁25(OH)D缺乏的老年人握力减退的发生率高于25(OH)D不足的老年人(45.0%vs.32.6%)和25(OH)D充足的老年人(45.0%vs.20.6%);25(OH)D缺乏的75~80岁老年人握力减退的发生率最高(62.1%),25(OH)D不足组次之(11.1%,P<0.05)。与25(OH)D充足的中老年人相比,25(OH)D缺乏的中老年人发生握力减退的风险增加1.4倍(OR=2.403,95%CI:1.202~4.804,P=0.013),未发现25(OH)D不足与中老年人握力状况存在显著相关关系;血清总25(OH)D每增加5μg/L,其发生握力减退的风险降低13.1%(OR=0.869,95%CI:0.768~0.982,P=0.025);血清25(OH)D 2每增加5μg/L,其发生握力减退的风险降低24.1%(OR=0.759,95%CI:0.582~0.990,P=0.042);未发现血清25(OH)D 3含量与握力减退风险存在显著相关关系。血清25(OH)D水平每增加一个等级(缺乏、不足和充足),中老年人发生握力减退的风险降低25.2%(OR=0.748,95%CI:0.598~0.936,P=0.011)。在65~80岁和65~69岁的两组调查对象中,血清25(OH)D水平每增加一个等级,发生握力减退的风险降低40.0%,而在75~80岁的调查对象中,25(OH)D水平每增加一个等级,发生握力减退的风险降低80.0%。结论:中国西部5城市中老年人血清总25(OH)D和25(OH)D 2含量与握力状况存在一定关联。

关键词：中国西部老年人 25羟基维生素D 握力

维普期刊数据库博看期刊

SERVICES AND COMMUNICATIONS IN FOG COMPUTING

在线全文

学校读者我要写书评

暂无评论

China Communications 2017年第11期14卷 I0001-I0002页

作者： shangguang wang ao zhou michael m.komarov stephen s.yau the state key laboratory of networking and switching technology beijing university of posts and telecommunications(bupt) the state key laboratory of networking and switching technology beijing university of posts and telecommunications department of innovation and business in information technologies national research university arizona state university(asu) the asu information assurance center

In the current cloud-based Internet-of-Things （IoT） model, smart devices （such as sensors, smartphones） exchange information through the Internet to cooperate and provide services to users, which could be citizens... 详细信息

关键词： SERVICES COMMUNICATIONS FOG COMPUTING

A Geometric Understanding of Deep Learning

在线全文

学校读者我要写书评

暂无评论

Engineering 2020年第3期6卷 361-374页

作者： Na Lei Dongsheng An Yang Guo Kehua Su Shixia Liu Zhongxuan Luo Shing-Tung yau Xianfeng Gu DUT-RU Co-Research Center of Advanced ICT for Active Life Dalian University of TechnologyDalian 116620China Department of Computer Science Stony Brook UniversityStony BrookNY 11794-2424USA School of Computer Science Wuhan UniversityWuhan 430072China School of Software Tsinghua UniversityBeijing 100084China Center of Mathematical Sciences and Applications Harvard UniversityCambridgeMA 02138USA

This work introduces an optimal transportation(OT)view of generative adversarial networks(GANs).Natural datasets have intrinsic patterns,which can be summarized as the manifold distribution principle:the distribution of a class of data is close to a low-dimensional *** mainly accomplish two tasks:manifold learning and probability distribution *** latter can be carried out using the classical OT *** the OT perspective,the generator computes the OT map,while the discriminator computes the Wasserstein distance between the generated data distribution and the real data distribution;both can be reduced to a convex geometric optimization ***,OT theory discovers the intrinsic collaborative-instead of competitive-relation between the generator and the discriminator,and the fundamental reason for mode *** also propose a novel generative model,which uses an autoencoder(AE)for manifold learning and OT map for probability distribution *** AE–OT model improves the theoretical rigor and transparency,as well as the computational stability and efficiency;in particular,it eliminates the mode *** experimental results validate our hypothesis,and demonstrate the advantages of our proposed model.

关键词： Generative Adversarial Deep learning Optimal transportation Mode collapse