检索结果-南通市图书馆

Efficient dynamic pruning on largest scores first (LSF) retrieval

Frontiers of Information Technology & Electronic Engineering 2016年第1期17卷 1-14页

作者： Kun JIANG Yue-xiang YANG College of Computer National University of Defense Technology

Inverted index traversal techniques have been studied in addressing the query processing performance challenges of web search engines, but still leave much room for improvement. In this paper, we focus on the inverted index traversal on document-sorted indexes and the optimization technique called dynamic pruning, which can efficiently reduce the hardware computational resources required. We propose another novel exhaustive index traversal scheme called largest scores first(LSF) retrieval, in which the candidates are first selected in the posting list of important query terms with the largest upper bound scores and then fully scored with the contribution of the remaining query terms. The scheme can effectively reduce the memory consumption of existing term-at-atime(TAAT) and the candidate selection cost of existing document-at-a-time(DAAT) retrieval at the expense of revisiting the posting lists of the remaining query terms. Preliminary analysis and implementation show comparable performance between LSF and the two well-known baselines. To further reduce the number of postings that need to be revisited, we present efficient rank safe dynamic pruning techniques based on LSF, including two important optimizations called list omitting(LSF_LO) and partial scoring(LSF_PS) that make full use of query term importance. Finally, experimental results with the TREC GOV2 collection show that our new index traversal approaches reduce the query latency by almost 27% over the WAND baseline and produce slightly better results compared with the Max Score baseline, while returning the same results as exhaustive evaluation.

关键词： Inverted index, Index traversal, Query latency, largest scores first (LSF) retrieval, Dynamic pruning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Several sharp upper bounds for the largest laplacian eigenvalue of a graph

引用

Science China Mathematics 2007年第12期50卷 1755-1764页

作者： Tian-fei WANG Department of Mathematics Leshan Teachers College Leshan 614004 China

Let K be the quasi-Laplacian matrix of a graph G and B be the adjacency matrix of the line graph of G, respectively. In this paper, we first present two sharp upper bounds for the largest Laplacian eigenvalue of G by applying the non-negative matrix theory to the similar matrix D-1/2 KD 1/2 and U-1/2 BU 1/2, respectively, where D is the degree diagonal matrix of G and U=diag(dudv: uv ∈ E(G)).And then we give another type of the upper bound in terms of the degree of the vertex and the edge number of G. Moreover, we determine all extremal graphs which achieve these upper bounds. Finally,some examples are given to illustrate that our results are better than the earlier and recent ones in some sense.

关键词： Laplacian matrix, the largest eigenvalue, similar matrix

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Distance signless Laplacian eigenvalues of graphs

引用

Frontiers of Mathematics in China 2019年第4期14卷 693-713页

作者： Kinkar Chandra DAS Huiqiu LIN Jiming GUO Department of Mathematics Sungkyunkwan University Suwon 16419 Republic of Korea Department of Mat hematics East China University of Science and Technology Shanghai 200237 China

Suppose that the vertex set of a graph G is V(G) ={v1,v2,...,vn}.The transmission Tr(vi) (or Di) of vertex vi is defined to be the sum of distances from vi to all other vertices.Let Tr(G) be the n × n diagonal matrix with its (i,i)-entry equal to TrG(vi).The distance signless Laplacian spectral radius of a connected graph G is the spectral radius of the distance signless Laplacian matrix of G,defined as L(G) =Tr(G) + D(G),where D(G) is the distance matrix of G.In this paper,we give a lower bound on the distance signless Laplacian spectral radius of graphs and characterize graphs for which these bounds are best possible.We obtain a lower bound on the second largest distance signless Laplacian eigenvalue of graphs.Moreover,we present lower bounds on the spread of distance signless Laplacian matrix of graphs and trees,and characterize extremal graphs.

关键词： Graph distance signless Laplacian spectral radius second largest eigenvalue of distance signless Laplacian matrix spread

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Human neural stem cell transplants to address multiple pathologies associated with traumatic brain injury

引用

Neural Regeneration Research 2019年第10期14卷 1699-1700页

作者： Helene Clervius Mirza Baig Anil Mahavadi Shyam Gajavelli University of Miami Miller School of Medicine

Traumatic brain injury (TBI), an unmet need: TBI is an alteration in brain function caused by an external force with evidence of brain pathology. It could be from a bump, blow, blast or jolt to the head including penetrating the cranium. TBI is a public health concern worldwide due to its economic impact. Most TBIs are survivable, do not need hospitalization but may influence productivity. A smaller percentage of TBI due to falls or penetrating TBI (PTBI) needs hospitalization and accounts for largest fraction of TBI care costs.

关键词： Traumatic brain injury(TBI) function caused by an external largest fraction of TBI care costs

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chaotic characteristics of pseudoplastic fluid induced by 6PBT impeller in a stirred vessel

引用

Chinese Journal of Chemical Engineering 2019年第2期27卷 293-297页

作者： Deyu Luan Yiming Chen Hong Wang Yue Wang Xing Wei College of Electromechanical Engineering Qingdao University of Science and Technology

Xanthan gum solutions with different mass concentrations were used to study the chaotic characteristics induced by the impeller of perturbed six-bent-blade turbine(6 PBT) in a stirred vessel. Based on the velocity time series obtained by the experiment of particle image velocimetry(PIV), with the software MATLAB(R2016a), the distributions of the largest Lyapunov exponent(LLE) and Kolmogorov entropy(K entropy) of the system, as two important parameters for characterizing the chaotic degree, were investigated respectively. Results showed that both of the LLE and K entropy increased with the increasing speed at the beginning. As the speed was up to 200 r·min-1, the two parameters reached the maximal values meanwhile, corresponding to 0.535 and 0.834, respectively, which indicated that the chaotic degree of the flow field was up to the highest level. When the speed was increased further, both of the LLE and K entropy decreased on the contrary, which meant that the chaotic degree was decreasing. It was also observed that the chaotic characteristics of flow field were hardly affected by the fluid rheology and the detecting positions. The research results will enhance the understanding of the chaotic mixing mechanism and provide a theoretical reference for optimizing impeller structure.

关键词： Chaos Pseudoplastic fluids largest Lyapunov exponent (LLE) Kolmogorov entropy (K entropy) Particle image velocimetry (PIV) 6PBT impeller

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The impact of income on household CO_2 emissions in China based on a large sample survey

引用

Science Bulletin 2019年第6期64卷 351-353页

作者： Jiansheng Qu Lina Liu Jingjing Zeng Zhiqiang Zhang Jinping Wang Huijuan Pei Liping Dong Qin Liao Tek Maraseni Information Center for Global Change Studies Lanzhou Information Center Chinese Academy of Sciences Key Laboratory of Western China’s Environmental Systems (Ministry of Education) College of Earth and Environmental Sciences Lanzhou University University of Southern Queensland

Since reform and opening-up, China's energy consumption has been soaring largely due to the country's rapid economic development and urbanization [1]. As a result, C02 emissions from the household sector have been rapidly increasing [2]. China—now the second largest global economy and the largest C02 emitter [3]—has been making efforts to aggressively reduce C02 emissions and protect the environment. In line with the Paris Climate Change Agreement, China submitted its Nationally Determined Contribution (NDC) and pledged to achieve peak C02 emissions by 2030.

关键词： Since reform energy consumption second largest global

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Class of Sums Involving the Smallest Prime Factor of an Integer

引用

Chinese Science Bulletin 1994年第14期39卷 1155-1160页

作者：曹惠中 Department of Mathematics Shandong University Jinan 250100 PRC

Let p(n) and Q(n) stand for the smallest and the largest prime factors of the natural number n, respectively. Recently, the sums involving reciprocals of the functions p(n) and Q(n) were studied by Erds, Ivié et al. ... 详细信息

关键词： the smallest prime factor the largest prime factor additive function.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of chaotic climatic process in the Tarim River Basin (I)

引用

Research in Cold and Arid Regions 2019年第5期11卷 340-349页

作者： ZuHan Liu Key Laboratory of the Education Ministry for Poyang Lake Wetland and Watershed Research Jiangxi Normal University Jiangxi Province Key Laboratory for Water Information Cooperative Sensing and Intelligent Processing Nanchang Institute of Technology

Based on observational data obtained from 1961 to 2011 in the Tarim River Basin,China,we investigated the chaotic dynamics of temperature,precipitation,relative humidity,and evaporation.The main findings are as follow:(1)The four data series have significant chaotic and fractal behaviors,which are the result of the evolution of a nonlinear chaotic dynamic system.The climatic process in the Tarim River Basin also has deterministic and stochastic characteristics.(2)To describe the temperature,precipitation,relative humidity,and evaporation dynamics,at least three independent variables at daily scale are required;in terms of complexity,their order is evaporation>temperature>precipitation>relative humidity.(3)Their respective largest Lyapunov exponentλ1 shows the order of their degree of complexity is relative humidity>temperature>precipitation≈evaporation;the maximum time scales for which the four systems can be predicted are 17 days,17 days,16 days,and 16 days,if calculated separately.(4)The Kolmogorov entropy K illustrates that the complexity of the nonlinear precipitation system is much greater than that of the other three systems.Both temperature and evaporation systems exhibit weaker chaotic behavior,their predictability is better,and the degree of complexity is less than that of the other two factors.

关键词： chaos climatic process largest Lyapunov exponent Kolmogorov entropy correlation dimension

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Discovery of the largest Carboniferous manganese deposit in Longtou-Limiao,central Guangxi,China

引用

China Geology 2018年第2期1卷 312-313页

作者： Xu Chen Sha Jiang Central South Geo-exploration Institute China Metallurgical Geology BureauWuhan 410080China Guangxi Geo-exploration Institute China Metallurgical Geology BureauNanning 530022China

1.Objective The Nandan-Yizhou faulting basin,which is located in Longtou-Limiao,Guangxi,is in the southern margin of the Yangtze Block,the depression zone of south Hunan and north Guangxi.It is a carbonate Manganese (Mn)ore deposit in the Baping Group,where occurs the Nongzhu large Mn deposit in a 100 km long anticlinorium with great Mn resource potential (Fig.1).

关键词： Discovery largest Carboniferous manganese Longtou-Limiao

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Noble strain of Sparassis latifolia produces high content of β-glucan

引用

Asian Pacific Journal of Tropical Biomedicine 2015年第8期5卷 615-621页

作者： Dong Ju Lee Min Cheol Jang A Ra Jo Hyun Jun Choi Kwang-Sang Kim Youn-Tae Chi School of Biological Sciences and Technology Chonnam National University Higher Education Center for Bioregulator Research Chonnam National University Jangheung Research Institute for Mushroom Industry 288 Woodland-gil Anyang-myun Jangheung-gun Jeollanam-do 529-851Republic of Korea

Objective: To classify four new Sparassis strains(CLM1, CKM1, CKM2, and KJM1) using the internal transcribed spacer sequence and to elucidate their β-glucan content and mycelial growth.Methods: Two different microbiological media were used to determine growth rate. The β-glucan contents were analyzed using the Megazyme Mushroom and Yeast Beta-Glucan kit. To determine the genetic relationships, phylogenetic trees were constructed using ClustalX. Multiple sequence alignments were printed and shaded with the BOXSHADE 3.21 program. Results: In this study, four new Sparassis strains were isolated from the southern region of the Korea Peninsula. They were all classified into the Sparassis latifolia clade as a monophyletic group based on the internal transcribed spacer sequence. Mycelial growth rate of the CLM1 strain was highest in potato dextrose agar and potato dextrose agar larch. The β-glucan content of the CLM1 strain was highest at 29.5%(w/w). A high degree of sequence divergence was detected in the RNA polymerase second largest subunit II gene(RPB2) within Sparassis spp. tested. The putative amino acid sequences of the RPB2 had a distinct sequence. The nucleotide sequences of the RPB2's intron were also divergent among Sparassis spp., even though their nucleotide length was well conserved within Sparassis latifolia. Conclusions: These results indicate that the nucleotide sequences and the amino acid sequences of RPB2 can be used to identify individual Sparassis sp. The Sparassis strain CLM1 may be best for developing a remedy to prevent or treat cancer and other chronic diseases.

关键词： Divergence β-Glucan Intron RNA polymerase second largest subunit II gene Sparassis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：