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A tetrahedral data model for unstructured data management

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Science china(Information Sciences) 2010年第8期53卷 1497-1510页

作者： LI Wei & lang bo state key laboratory of software development environment, beihang university, beijing 100191, china 1. state key laboratory of software development environment Beihang University Beijing 100191 China

This paper proposes a tetrahedral data model for unstructured data management. The model defines the four components of unstructured data including: basic attributes, semantic characteristics, low-level features and raw data on its four facets, and the relations between these components. The internal implementation structure of the model and the data query language are designed and briefly introduced. This model provides a unified, integrated and associated description for different kinds of unstructured data, and supports intelligent data services such as associated retrieval and data mining. An example is given to demonstrate how to use the model for describing and manipulating data from a sample video base.

关键词： unstructured data data model query language associated retrieval intelligent services

Reliability-aware automatic composition approach for web services

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Science china(Information Sciences) 2012年第4期55卷 921-937页

作者： LI Mu 1,2,LI bo 1,2 & HUAI JinPeng 1,2 1 state key laboratory of software development environment,beihang university,beijing 100191,china 2 School of Computer Science and Engineering,beihang university,beijing 100191,china 1. state key laboratory of software development environment Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

In this paper,we study the reliability-aware synthesis problem for composing available services automatically and guaranteeing that the composed result satisfies the specification,such as temporal constraints of functionality and reliability,centered on a synthesis model for mediator of web services composition (CSM).This approach focuses on handling attributes and state relations,and permitting users and services to operate over them,i.e.,read /write their data values and compare them according to a dense state *** show that the reliability-aware synthesis problem for the specification is EXPTIME-complete and we give an exponential-time algorithm (CSM-NSA) which for a given formula ψ and a synthesis model,synthesizes available services in the library satisfying ψ over the synthesis model (if they exist) or responds with "not satisfiable" (otherwise).The specification ψ is a fragment of PCTL (probabilistic computation tree logic),obtained from "ordinary" CTL (computation tree logic) by replacing the EX,AX,EU and AU operation with their quantitative counterparts X >p,X =1,U >p,and U =1,*** opposed to NSA,we provide a more effective algorithm to replace the NSA algorithm called CSM-HSA (heuristic synthesis algorithm).Though HSA is an incomplete algorithm,the answer is *** experiments show that the HSA algorithm solves the problem of reliability-aware service synthesis effectively and efficiently.

关键词： reliability web services synthesis problem synthesis model heuristic algorithm

Lightweight SOA-Based Twin-Engine Architecture for Enterprise Systems in Fixed and Mobile environments

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china Communications 2016年第9期13卷 183-194页

作者： Tongguang Zhang Shuai Zhao Budan Wu Maurizio Farina bo Cheng Junliang Chen state key laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China Adaptive software Company Via Posillipo 255Naples 80123Italy

Mobile devices as a popular computing platform for enterprise systems have enabled certain tasks to be executed out of ***,the work may be interrupted due to the server shutdown or network disconnection when employees access traditional single-engine Business Process Management *** overcome this defect,we present a lightweight twin-engine architecture based on Service Oriented Architecture(SOA).In this paper,we discuss in detail the design and implementation of the architecture,and present a trigger mechanism to activate engines according to the states of hybrid environments since it is critical for the two types of engines to cooperate closely in hybrid environments with fixed and mobile computing *** experimental results validate the usability of the architecture.

关键词： twin-engine SOA enterprise system mobile environment

Progress in efficient doping of Al-rich AlGaN

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Journal of Semiconductors 2024年第2期45卷 10-20页

作者： Jiaming Wang Fujun Xu Lisheng Zhang Jing lang Xuzhou Fang Ziyao Zhang Xueqi Guo Chen Ji Chengzhi Ji Fuyun Tan Xuelin Yang Xiangning Kang Zhixin Qin Ning Tang Xinqiang Wang Weikun Ge bo Shen state key laboratory of Artificial Microstructure and Mesoscopic Physics School of PhysicsPeking UniversityBeijing 100871China beijing SinoGaN Semiconductor Technology Co. Ltd.Beijing 101399China Nano-optoelectronics Frontier Center of Ministry of Education Peking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China

The development of semiconductors is always accompanied by the progress in controllable doping *** AlGaN-based ultraviolet(UV)emitters as an example,despite a peak wall-plug efficiency of 15.3%at the wavelength of 275 nm,there is still a huge gap in comparison with GaN-based visible light-emitting diodes(LEDs),mainly attributed to the inefficient doping of AlGaN with increase of the Al ***,p-doping of Al-rich AlGaN is a long-standing challenge and the low hole concentration seriously restricts the carrier injection *** p-GaN cladding layers are widely adopted as a compromise,the high injection barrier of holes as well as the inevitable loss of light extraction cannot be *** in terms of n-doping the main issue is the degradation of the electrical property when the Al composition exceeds 80%,resulting in a low electrical efficiency in sub-250 nm *** review summarizes the recent advances and outlines the major challenges in the efficient doping of Al-rich AlGaN,meanwhile the corresponding approaches pursued to overcome the doping issues are discussed in detail.

关键词： AlGaN-based UV-LEDs Al-rich AlGaN doping

Empowering smart city situational awareness via big mobile data

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Frontiers of Information Technology & Electronic Engineering 2024年第2期25卷 286-307页

作者： Zhiguang SHAN Lei SHI bo LI Yanqiang ZHANG Xiatian ZHANG Wei CHEN state Information Center Beijing100045China School of Computer Science and Engineering Beihang UniversityBeijing100191China Zhongguancun laboratory Beijing100094China beijing Tendcloud Tianxia Technology Co. Ltd.Beijing100027China The state key Lab of CAD&CG Zhejiang UniversityHangzhou310027China

Smart city situational awareness has recently emerged as a hot topic in research societies,industries,and governments because of its potential to integrate cutting-edge information technology and solve urgent challenges that modern cities *** example,in the latest five-year plan,the Chinese government has highlighted the demand to empower smart city management with new technologies such as big data and Internet of Things,for which situational awareness is normally the crucial first *** traditional static surveillance data on cities have been available for decades,this review reports a type of relatively new yet highly important urban data source,i.e.,the big mobile data collected by devices with various levels of mobility representing the movement and distribution of public and private agents in the *** especially focus on smart city situational awareness enabled by synthesizing the localization of hundreds of thousands of mobile software Apps using the Global Positioning System(GPS).This technique enjoys advantages such as a large penetration rate(∼50%urban population covered),uniform spatiotemporal coverage,and high localization *** first discuss the pragmatic requirements for smart city situational awareness and the challenges *** we introduce two suites of empowering technologies that help fulfill the requirements of(1)cybersecurity insurance for smart cities and(2)spatiotemporal modeling and visualization for situational awareness,both via big mobile *** main contributions of this review lie in the description of a comprehensive technological framework for smart city situational awareness and the demonstration of its feasibility via real-world applications.

关键词： Smart city Mobile data Situational awareness

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Tsinghua Science and Technology 2017年第6期22卷 619-632页

作者： Ming Liu bo lang Zepeng Gu Ahmed Zeeshan state key laboratory of Soflware development environment Beihang University Beijing 100191 China

Long-document semantic measurement has great significance in many applications such as semantic searchs, plagiarism detection, and automatic technical surveys. However, research efforts have mainly focused on the semantic similarity of short texts. Document-level semantic measurement remains an open issue due to problems such as the omission of background knowledge and topic transition. In this paper, we propose a novel semantic matching method for long documents in the academic domain. To accurately represent the general meaning of an academic article, we construct a semantic profile in which key semantic elements such as the research purpose, methodology, and domain are included and enriched. As such, we can obtain the overall semantic similarity of two papers by computing the distance between their profiles. The distances between the concepts of two different semantic profiles are measured by word vectors. To improve the semantic representation quality of word vectors, we propose a joint word-embedding model for incorporating a domain-specific semantic relation constraint into the traditional context constraint. Our experimental results demonstrate that, in the measurement of document semantic similarity, our approach achieves substantial improvement over state-of-the-art methods, and our joint word-embedding model produces significantly better word representations than traditional word-embedding models.

关键词： document semantic similarity text understanding semantic enrichment word embedding scientific literature analysis

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突变结构对π型管气流脉动的影响

化工设备与管道 2024年第4期61卷 56-63页

作者：谭红莹刘健郎子进纪志远司红涛单世超周波海洋石油工程股份有限公司设计院天津300461 大连理工大学工程工业装备结构分析优化与CAE软件国家重点实验室船舶工程学院辽宁大连116024

世界能源发展呈现低碳趋势,人们对天然气的需求日益增加。输运管道中由于气流脉动遇到弯头、变径管等突变结构而形成的激振力是管道振动的主要成因。π型管是天然气管道中常见的柔性补偿结构,常与压缩机出口的管路相连,往复式压缩机工... 详细信息

世界能源发展呈现低碳趋势,人们对天然气的需求日益增加。输运管道中由于气流脉动遇到弯头、变径管等突变结构而形成的激振力是管道振动的主要成因。π型管是天然气管道中常见的柔性补偿结构,常与压缩机出口的管路相连,往复式压缩机工作时产生的气流脉动在π型管处诱发的流致振动较为明显。文章基于计算流体动力学对含有突变结构的π型管进行气流脉动仿真分析,研究脉动幅值与突变结构的关系。结果显示,含突变结构的管道出口处的压力不均匀度比π型管分别高了3.8%和4.6%左右,当突变结构的尺寸从100 mm变化到200 mm时,管道出口处的压力不均匀度也从15.5%左右变化到19.9%左右,可以看出突变结构对π型管内部的气流脉动呈现出不利影响,在实际工程应用中应尽量避免突变结构的使用。

关键词：气流脉动流致振动突变结构减振

Relation between microstructure and magnetic properties of shock wave-compressed Nd-Fe-B magnets

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Rare Metals 2022年第7期41卷 2353-2356页

作者： Ming-Gang Zhu Yan-Feng Li Wei Li Li-Yun Zheng Dong Zhou Hai-bo Feng lang Chen An Du Division of Functional Materials Central Iron and Steel Research InstituteBeijing 100081China state key laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China College of Science Northeastern UniversityShenyang 110819China

The relationship between the microstructure and magnetic properties of Nd-Fe-B sintered magnet compressed by shock wave with 6.26 GPa≤p≤7.16 GPa was *** reveals that Nd-Fe-B magnets show a demagnetization behavior after compressed by shock *** intergranular fracture is the main occurring phe-nomenon in the shock wave-compressed *** coercivity of the shock wave-compressed Nd-Fe-B magnets could be recovered after repeating the annealing *** suggests that only the morphology change just like the intergranular fracture occurs,and there is no structural change in the grain boundary phase in the shock wave-compressed *** phase grain interconnection,microcracks and pores,and alterant orientation relationship between matrix phase and grain boundaries phase are con-sidered as induced factors of demagnetization.

关键词： Permanent magnets Coercivity Shock wave Demagnetization

Adsorption of methane onto mudstones under supercritical conditions: Mechanisms, physical properties and thermodynamic parameters

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Petroleum Science 2023年第1期20卷 34-47页

作者： Yang Wang Hong-Fei Cheng Qin-Hong Hu lang-bo Jia Xi-Meng Wang Sha-Sha Gao Luo-Fu Liu School of Earth Science and Resources Chang'an UniversityXi'anShaanxi710054China key laboratory of West Mineral Resources and Geological Engineering of Ministry of Education Chang'an UniversityXi'anShaanxi710054China Department of Earth and environmental Sciences The University of Texas at ArlingtonArlingtonTX76019USA Exploration and development Research Institute Changqing Oil FieldPetroChinaXi'anShaanxi710000China Department of Geology and Geophysics Texas A&M UniversityCollege StationTX77843USA state key laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China

Since the mechanisms of methane-mudstone interactions are important for estimating shale gas reserves,methane adsorption under supercritical conditions of 30 MPa pressure and 303.15,333.15,363.15 K temperatures was studied to measure the excess methane adsorption in two mudstone samples from Yanchang Formation,Ordos *** adsorption features inflection points where the amount of adsorbed gas changes from increasing to decreasing *** methods(fixed,slope,and freely fitted density)were applied to calculate the adsorbed-phase density(rad),which was then used to fit the measured excess *** criteria,the goodness-of-fit and whether the fitting can obtain reasonable absolute adsorption,were applied to determine the most accurate *** indicated that the supercritical Dubinin-Radushkevich(SDR)model with freely fitted rad was the most reasonable *** volume of adsorbed methane at 363.15 K is close to the micropore(d<2 nm)volume of the corresponding *** the actual geological conditions,the adsorbed gas should be predominantly stored in *** parameters reveal that the methane adsorption on mudstone is a physisorption process that is jointly controlled by the heterogeneity of,and interaction forces between the methane molecule and,the rock surface.

关键词： Supercritical methane adsorption Excess adsorption Adsorbed-phase density Adsorption model Thermodynamic feature