检索结果-内蒙古大学图书馆

Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing 2008年第4期30卷 339-343页

作者： Tan, Zhuoying Yue, Z.Q. Tham, L.G. Lee, C.F. Key Lab. of the Ministry of Education of China for High-Efficient Mining and Safety of Metal Mines University of Science and Technology Beijing Beijing 100083 China School of Civil and Environmental Engineering University of Science and Technology Beijing Beijing 100083 China Department of Civil Engineering University of Hong Kong Pokfulam Road Hong Kong Hong Kong

Based on experimental data from a drilling process monitoring system instrumented with a hydraulic rotary drill rig in fill-weathered granite formation, the diamond penetrating energy was analyzed. The result shows that the distribution of the penetrating energy in fill-weathered granite formation agrees with that in common weathered granite formation. A negative correlation between the viscous energy, kinetic energy, total penetrating energy and the weathered degree of granite existed, and a positive correlation between the thrust force energy and the weathered degree was presented, which indicates that there is a well response between the penetrating energy and the weathered degree of rock. However, the kinetic energy, thrust force energy and viscous energy are limited in identification of formation because of different effects in various drilling modes. The specific energy of diamond drilling (SEDD) increased with the weathered degree of rock and the values of SEDD can be classified into corresponding range according to the weathered degree of rock. It is shown that the SEDD in rotary drilling is apparently less than the specific energy of percussive drilling (SEPD) in both fill soil and very strongly weathered granite formation. Reversely, the SEDD is much more than the SEPD in lightly weathered hard rock.

关键词： Diamond drilling

来源：评论

学校读者我要写书评

暂无评论

Indexing Future Trajectories of Moving Objects in a Constrained Network

引用

Journal of Computer Science & Technology 2007年第2期22卷 245-251页

作者：陈继东孟小峰 School of Information Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Beijing 100872 China

Advances in wireless sensor networks and positioning technologies enable new applications monitoring moving objects. Some of these applications, such as traffic management, require the possibility to query the future trajectories of the objects. In this paper, we propose an original data access method, the ANR-tree, which supports predictive queries. We focus on real life environments, where the objects move within constrained networks, such as vehicles on roads. We introduce a simulation-based prediction model based on graphs of cellular automata, which makes full use of the network constraints and the stochastic traffic behavior. Our technique differs strongly from the linear prediction model, which has low prediction accuracy and requires frequent updates when applied to real traffic with velocity changing frequently. The data structure extends the R-tree with adaptive units which group neighbor objects moving in the similar moving patterns. The predicted movement of the adaptive unit is not given by a single trajectory, but instead by two trajectory bounds based on different assumptions on the traffic conditions and obtained from the simulation. Our experiments, carried on two different datasets, show that the ANR-tree is essentially one order of magnitude more efficient than the TPR-tree, and is much more scalab.e.

关键词： database spatial database access methods moving objects

来源：评论

学校读者我要写书评

暂无评论

CLASCN： Candidate Network Selection for Efficient Top-κ keyword Queries over databases

引用

Journal of Computer Science & Technology 2007年第2期22卷 197-207页

作者：张俊彭朝晖王珊聂惠静 School of Information Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Beijing 100872 China Computer Science and Technology College Dalian Maritime University Dalian 116026 China

keyword Search Over Relational databases （KSORD） enables casual or Web users easily access databases through free-form keyword queries. Improving the performance of KSORD systems is a critical issue in this area. In this paper, a new approach CLASCN （Classification, Learning And Selection of Candidate Network） is developed to efficiently perform top-κ keyword queries in schema-graph-based online KSORD systems. In this approach, the Candidate Networks （CNs） from trained keyword queries or executed user queries are classified and stored in the databases, and top-κ results from the CNs are learned for constructing CN Language Models （CNLMs）. The CNLMs are used to compute the similarity scores between a new user query and the CNs from the query. The CNs with relatively large similarity score, which are the most promising ones to produce top-κ results, will be selected and performed. Currently, CLASCN is only applicable for past queries and New All-keyword-Used （NAU） queries which are frequently submitted queries. Extensive experiments also show the efficiency and effectiveness of our CLASCN approach.

关键词： relational database keyword search top-κ query candidate network

来源：评论

学校读者我要写书评

暂无评论

The rewriting algorithm for disjunctive queries between peer ontologies

The rewriting algorithm for disjunctive queries between peer...

引用

3rd International Conference on Semantics, knowledge, and Grid, SKG 2007

作者： Qin, Biao Wang, Shan Dept. of Computer Science Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Beijing 100872 China

ISBN: (纸本)0769530079

We study the problem of answering queries given a set of mappings between peer ontologies. In addition to the schema mapping between peer ontologies, there are axioms to give constraints to classes and properties. We propose a set of rules to build graphs for the axioms. Because the axioms have different properties, the generated graphs are classified into four sets. In each peer, its RDF/OWL query languages can support regular expressions. If it wants to be transitive along semantic paths in peer knowledge management systems, we must rewrite conjunctive and disjunctive queries between peers. Because conjunctive queries are well-understood, we focus on a novel algorithm to rewrite disjunctive queries along semantic paths based on the graphs. For all atoms of a disjunctive query, we consider its union as a set and find the maximum rewritings over peers through a graphical way. Finally we do extensive simulation experiments. The simulation results show our algorithm can generate more rewritings than the naive rewriting algorithm at each distance. © 2007 IEEE.

关键词： Ontology

来源：评论

学校读者我要写书评

暂无评论

Phylogenetic relationships of host insects of Cordyceps sinensis inferred from mitochondrial Cytochrome b sequences

引用

Progress in Natural Science:Materials International 2007年第7期17卷 789-797页

作者： Cheng Zhou~(1,2**) Geng Yang~1 Liang Honghui~1 Yang Xiaoling~1 Li Shan~1 Zhu Yunguo~1 Guo Guangpu~1 Zhou Tongshui~2 Chen Jiakuan~2 (1.School of Life Science and Technology,Tongji University,Shanghai 200092,China 2.ministry of education key lab.ratory for Biodiversity Science and Ecological engineering,Institute of Biodiversity Science,Fudan University,Shanghai 200433,China) School of Life Science and Technology Tongji University Shanghai 200092 China Ministry of Education Key Lab. for Biodiversity Science and Ecological Engineering Institute of Biodiversity Science Fudan University Shanghai 200433 China

This study used the sequence of the mitochondrial Cytochrome b(Cytb)to estimate phylogenetic relationships among host Hepialidae insects of Cordyceps *** DNA of host insect was extracted from the dead larva head part of 18 cordyceps populations and 2 species of Hepialus,and the Cytb fragment of host insect was amplified with PCR *** nucleotide sequence alignments and their homologous sequences of 24 species host Hepialidae insects of Cordyceps sinensis were obtained from GenBank and were used to construct phylogenetic trees based on neighbor-joining *** results showed that genus Bipectilus diverged earlier than genus Hepialus and *** host insects of Cordyceps sinensis have multitudinous species with different morphological characteristics and geographical *** interspecific genetic differentiations are obvious in ***,the genus Hepialus might be considered as polyphyletic *** sequences have abundant variations among the host insects of Cordyceps sinensis on spe- cific and generic *** divergence rate of Cytb sequences among the species in Hepialus ranged from 0.23% to 9.24%,except that Hepialus pratensis and Hepialus jinshaensis have the same *** sequence can be used for species identification of host insects of Cordyceps sinensis,but further confirmation in more host insect species is *** obtain the Cytb sequence of host insect by ampli- fying DNA extracted from the head part of dead larva in cordyceps turns out to be an effective and accurate approach,which will be useful for studies on phylogeny and genetic structure of host insects of cordyceps populations,especially for analyzing relationships between C. sinensis and its host insects.

关键词： mitochondrial Cytochrome b Cordyceps sinensis Hepialus phylogeny

来源：评论

学校读者我要写书评

暂无评论

Fluidized-bed pyrolysis of waste bamboo

引用

Journal of Zhejiang University-Science A(Applied Physics & engineering) 2007年第9期8卷 1495-1499页

作者： XIAO Gang NI Ming-jiang HUANG He CHI Yong XIAO Rui ZHONG Zhao-ping CEN Ke-fa Key Lab. on Clean Coal Power Generation and Combustion Technology of Ministry of Education School of Energ3＂ and Environment Southeast University Nanjing 210096. China State Key Lab. of Clean Energy Utilization College of Mechanical and Energy Engineering Zhejiang University Hangzhou 310027 China College of Lfe Science and Pharmaceutical Engineering Nanjing University of Technology Nanjing 210009 China

Bamboo was a popular material substituting for wood, especially for one-off commodity in China. In order to recover energy and materials from waste bamboo, the basic characteristics of bamboo pyrolysis were studied by a thermogravimetric analyzer. It implied that the reaction began at 190-210℃, and the percentage of solid product deceased from about 25% to 17% when temperature ranged from 400℃ to 700℃. A lab.scale fluidized-bed furnace was setup to research the detailed properties of gaseous, liquid and solid products respectively. When temperature increased from 400℃ to 700℃, the mass percent of solid product decreased from 27% to 17% approximately, while that of syngas rose up from 19% to 35%. When temperature was about 500℃, the percentage of tar reached the top, about 31%. The mass balance of these experiments was about 93%-95%. It indicated that three reactions involved in the process： pyrolysis of exterior bamboo, pyrolysis of interior bamboo and secondary pyrolysis of heavy tar.

关键词： Bamboo Pyrolysis Fluidized beds Syngas Tar

来源：评论

学校读者我要写书评

暂无评论

Study on damages constitutive model of rocks based on lognormal distribution

引用

Journal of Coal Science & engineering(China) 2007年第4期13卷 430-433页

作者：李树春许江陶云奇唐晓军 Key lab. for the Exploitation of Southwestern Resources ＆ the Environmental Disaster Control Engineering Ministry of Education Chongqing University Chongqing 400044 China

The damage constitutive relation of entire rock failure process was established using the theory of representative volume element obeying the Iognormal distribution law, and the integrated damages constitutive model of rock under triaxial compression was established. Comparing with triaxial compression test result, it shows that this model correctly reflects the relationship of stress-strain. At the same time, according to the principle of the rock fatigue failure that conforms to completely the static entire process curve, a new method of establishing cyclic fatigue damage evolution equation was discussed, this method form is simple and the physics significance is clear, it may join preferably the damage relations of the rock static entire process curve.

关键词： constitutive model rock damage fatigue

来源：评论

学校读者我要写书评

暂无评论

Preparation and flame ablation/oxidation behavior of ZrB2/SiC ultra-high temperature ceramic composites

引用

key engineering Materials 2007年 351卷 142-146页

作者： Wang, Chang-An Wang, Hailong Huang, Yong Fang, Daining State Key Lab. of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China Key Lab. of Material Physics Ministry of Education Zhengzhou University Henan 450000 China School of Aerospace Tsinghua University Beijing 100084 China

ZriB2/SiC ceramic composites reinforced by nano-SiC whiskers and SiC particles have been prepared by hot-pressing at 1950°C for 1hr under 20 MPa pressure in flow argon atmosphere. Effects of SiC addition on microstructure, mechanical properties and thermal ablation/oxidation behavior of ZrB2/SiC composites were investigated. The results showed that the addition of SiC effectively improved the densification of ZrB2/SiC composites and almost full dense ZrB2/SiC composites were obtained when the amount of SiC increased up to 20 vol%. Flexural strength and fracture toughness of the ZrB2/SiC composites were also enhanced;the maximum strength and toughness reached 600 MPa and 8.81 MPa'rn1/2 at SiC additions of 20 vol % and 30 vol%, respectively. The composites possessed good resistance to flame ablation and could keep the whole shape without distinct peeling or cracking after flame ablation by oxyacetylene flame for 3 mins. The more SiC added, the better resistance to flame ablation the composites displayed.

关键词： Ceramic materials

来源：评论

学校读者我要写书评

暂无评论

Adaptive beamforming passive radar based on FM radio transmitter

Adaptive beamforming passive radar based on FM radio transmi...

引用

RADAR 2007 - The Institution of engineering and Technology International Conference on Radar Systems

作者： Zhu, Jiabing Hong, Yi Tao, Liang East China Research Institute of Electronic Engineering China Education Ministry Key Lab. of Intelligent Computing and Signal Processing Anhui University China

ISBN: (纸本)9780863418488

One of the major problems in continuous wave bistatic radar based on FM radio transmitter is direct path interference(DPI). This is the signal received directly from a transmitter by the receive channel antenna. The DPI and the reflected signal are coherent, have similar structure except for the mutual delay and Doppler frequency shift. To detect targets it is necessary to suppress or remove the DPI signal. First of all, the DPI signal based on FM radio transmitter is analyzed. Secondly, the approach based on adaptive nulling array processing is introduced in detail to solve this problem. Finally, associated signal processing schemes of the FM-radio-based passive radar is discussed. Simulation results by applying real collected data show the proposed method is effective.

关键词： Beamforming

来源：评论

学校读者我要写书评

暂无评论

A novel adaptive filtering algorithm for SAR speckle reduction

A novel adaptive filtering algorithm for SAR speckle reducti...

引用

2007 1st Asian and Pacific Conference on Synthetic Aperture Radar, APSAR 2007

作者： Zhu, Jiabing Chen, Renyuan Hong, Yi East China Research Institute of Electronic Engineering China Education Ministry Key Lab. of Intelligent Computing and Signal Processing Anhui University China

ISBN: (纸本)1424411882

The novel adaptive filtering algorithm based on the analysis of the detail images obtained from the wavelet decomposition of the original noisy image is proposed in the paper. The base idea is to compute the wavelet decomposition of the noisy image to reduce the amplitude of insignificant detail coefficients in the wavelet subspaces by selecting an adaptive filter window of size, the adaptive windowing algorithm was introduced where the window size is automatically adjusted depending on the samples statistics in the boundary of this window such as mean z and standard deviation σz, and then utilizing modified 2nd order Lee filtering. One of the advantages of this approach over the traditional speckle filtering method is the fact that textures are preserved while speckle is reduced. Experimental simulations by real SAR images show it are effective. © 2007 IEEE.

关键词： Wavelet decomposition

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：