We address several load shedding techniques over sliding window joins. We first construct a dual window architectural model including aux-windows and join-windows, and build statistics on aux-windows. With the statist...We address several load shedding techniques over sliding window joins. We first construct a dual window architectural model including aux-windows and join-windows, and build statistics on aux-windows. With the statistics, we develop an effective load shedding strategy producing maximum subset join outputs. In order to accelerate the load shedding process, binary indexed trees have been utilized to reduce the cost on shedding evaluation. When streams have high arrival rates, we propose an approach incorporating front-shedding and rear-shedding, and find an optimal trade-off between them. As for the scenarios of variable speed ratio, we develop a plan reallocating CPU resources and dynamically resizing the windows. In addition, we prove that load shedding is not affected during the process of reallocation. Both synthetic and real data are used in our experiments, and the results show the promise of our strategies.展开更多
In this systems paper,we present MillenniumDB:a novel graph database engine that is modular,persistent,and open source.MillenniumDB is based on a graph data model,which we call domain graphs,that provides a simple abs...In this systems paper,we present MillenniumDB:a novel graph database engine that is modular,persistent,and open source.MillenniumDB is based on a graph data model,which we call domain graphs,that provides a simple abstraction upon which a variety of popular graph models can be supported,thus providing a flexible data management engine for diverse types of knowledge graph.The engine itself is founded on a combination of tried and tested techniques from relational data management,state-of-the-art algorithms for worst-case-optimal joins,as well as graph-specific algorithms for evaluating path queries.In this paper,we present the main design principles underlying MillenniumDB,describing the abstract graph model and query semantics supported,the concrete data model and query syntax implemented,as well as the storage,indexing,query planning and query evaluation techniques used.We evaluate MillenniumDB over real-world data and queries from the Wikidata knowledge graph,where we find that it outperforms other popular persistent graph database engines(including both enterprise and open source alternatives)that support similarqueryfeatures.展开更多
The Asian Infrastructure InvestmentBank＇s （AIIB） Board of Governorshas approved the membershipapplication of the Republic of Lebanon, bringing AIIB＇s totalapproved membership to 87,according to the bank＇s officia...The Asian Infrastructure InvestmentBank＇s （AIIB） Board of Governorshas approved the membershipapplication of the Republic of Lebanon, bringing AIIB＇s totalapproved membership to 87,according to the bank＇s official.website on June 26.展开更多
Adhesive Single Lap Joints have been subjected to tensile and bending investigations by many researchers. However, the joint is also likely to experience buckling loading in some aerospace applications. The aim of thi...Adhesive Single Lap Joints have been subjected to tensile and bending investigations by many researchers. However, the joint is also likely to experience buckling loading in some aerospace applications. The aim of this work is to investigate the joint behaviour under quasi-static buckling conditions. For this purpose, the joints with three different adherend thicknesses and 25 mm overlap length were tested using two different types of adherends and an adhesive film. They were modelled using a non-linear Finite Element Method via the ABAQUS Explicit package programme.Load to failure and stress distributions in the joints were predicted and compared with the experimental results, which were found in a good agreement. The adhesive layer in the joint was assumed to experience shear stresses under the buckling mode, similar to that in tensile loading, yet, the stress concentrations at the ends of the overlap, the main cause of the failure, resulted in different effects on the joint performance;for the buckling mode the critical stresses were in compression but for the tensile case in peeling. Unlike the latter, the former was found to prevent failure of the layer depending on the adherend thickness, causing different failure mechanisms. There were two different failure modes of the joints;a complete failure in the adhesive layer and large plastic deformation of adherends which could be a good source for crashworthiness situations. Mechanical properties of the adherends were found to play important roles on the joint performance.展开更多
Multi-way join is critical for many big data applications such as data mining and knowledge discovery. Even though lots of research have been devoted to processing multi-way joins using MapReduce, there are still seve...Multi-way join is critical for many big data applications such as data mining and knowledge discovery. Even though lots of research have been devoted to processing multi-way joins using MapReduce, there are still several problems in general to be further improved, such as transferring numerous unpromising intermediate data and lacking of better coordination mechanisms. This work proposes an efficient multi-way joins processing model using MapReduce, named Sharing-Coordination-MapReduce (SC-MapReduce), which has the functions of sharing and coordination. Our SC-MapReduce model can filter the unpromising intermediatedata largely by using the sharing mechanism and optimize the multiple tasks coordination of multi-way joins. Extensive experiments show that the proposed model is efficient, robust and scalable.展开更多
On July 1, 1997, Hong Kong finally returns to the motherland. July 1 was a day of Chinese national pride. Looking back, Hong Kong experienced great changes and the Chinese nation was subjected to humiliation during th...On July 1, 1997, Hong Kong finally returns to the motherland. July 1 was a day of Chinese national pride. Looking back, Hong Kong experienced great changes and the Chinese nation was subjected to humiliation during the 156 years. The Chinese nation had expected and made unremitting efforts to become stronger for more than 100 years. After resuming sovereignty over Hong Kong, the Chinese government will bring a brighter future to Hong Kong under the policies of "one country, two systems," and "Hong Kong people governing Hong Kong, with a high degree of autonomy." Hong Kong and the mainland will conduct more economic and cultural exchanges and create a more splendid future for the motherland.展开更多
Zhao Xianming, a narcotics control liaison officer for Mengla county in southwest China＇s Yunnan Province,clearly remembered the circumstances of that Saturday.
As the data managed by applications has evolved over the years with the arrival of Web 2.0,a large number of new databases have been developed to manage various types of data.While the traditional relational databases...As the data managed by applications has evolved over the years with the arrival of Web 2.0,a large number of new databases have been developed to manage various types of data.While the traditional relational databases continue to exist,NoSQL databases which are document oriented or key-value stores or columnar continue to evolve and are embraced very rapidly across the industry.It is not just the type of data handled by these databases that is different but also the query language they use is also different.This paper talks about a uniform query framework that can be used for traditional relational databases and NoSQL databases.This query framework can also perform joins,aggregates,filter on data from various data sources in a single query.展开更多
China＇s arduous war against the HIV/AIDS plague gained a powerful new warrior when the State Industry ＆ Commerce Administration （SICA） integrated an HIV prevention message into its routine duties.
基金This work is supported by the National Natural Science Foundation of China under Grant Nos. 60473074, 60573089 and National Grand Fundamental Research 973 Program of China under Grant No. 2006CB303103.
文摘We address several load shedding techniques over sliding window joins. We first construct a dual window architectural model including aux-windows and join-windows, and build statistics on aux-windows. With the statistics, we develop an effective load shedding strategy producing maximum subset join outputs. In order to accelerate the load shedding process, binary indexed trees have been utilized to reduce the cost on shedding evaluation. When streams have high arrival rates, we propose an approach incorporating front-shedding and rear-shedding, and find an optimal trade-off between them. As for the scenarios of variable speed ratio, we develop a plan reallocating CPU resources and dynamically resizing the windows. In addition, we prove that load shedding is not affected during the process of reallocation. Both synthetic and real data are used in our experiments, and the results show the promise of our strategies.
基金supported by ANID-Millennium Science Initiative Program-Code ICN17_002。
文摘In this systems paper,we present MillenniumDB:a novel graph database engine that is modular,persistent,and open source.MillenniumDB is based on a graph data model,which we call domain graphs,that provides a simple abstraction upon which a variety of popular graph models can be supported,thus providing a flexible data management engine for diverse types of knowledge graph.The engine itself is founded on a combination of tried and tested techniques from relational data management,state-of-the-art algorithms for worst-case-optimal joins,as well as graph-specific algorithms for evaluating path queries.In this paper,we present the main design principles underlying MillenniumDB,describing the abstract graph model and query semantics supported,the concrete data model and query syntax implemented,as well as the storage,indexing,query planning and query evaluation techniques used.We evaluate MillenniumDB over real-world data and queries from the Wikidata knowledge graph,where we find that it outperforms other popular persistent graph database engines(including both enterprise and open source alternatives)that support similarqueryfeatures.
文摘The Asian Infrastructure InvestmentBank＇s （AIIB） Board of Governorshas approved the membershipapplication of the Republic of Lebanon, bringing AIIB＇s totalapproved membership to 87,according to the bank＇s official.website on June 26.
文摘Adhesive Single Lap Joints have been subjected to tensile and bending investigations by many researchers. However, the joint is also likely to experience buckling loading in some aerospace applications. The aim of this work is to investigate the joint behaviour under quasi-static buckling conditions. For this purpose, the joints with three different adherend thicknesses and 25 mm overlap length were tested using two different types of adherends and an adhesive film. They were modelled using a non-linear Finite Element Method via the ABAQUS Explicit package programme.Load to failure and stress distributions in the joints were predicted and compared with the experimental results, which were found in a good agreement. The adhesive layer in the joint was assumed to experience shear stresses under the buckling mode, similar to that in tensile loading, yet, the stress concentrations at the ends of the overlap, the main cause of the failure, resulted in different effects on the joint performance;for the buckling mode the critical stresses were in compression but for the tensile case in peeling. Unlike the latter, the former was found to prevent failure of the layer depending on the adherend thickness, causing different failure mechanisms. There were two different failure modes of the joints;a complete failure in the adhesive layer and large plastic deformation of adherends which could be a good source for crashworthiness situations. Mechanical properties of the adherends were found to play important roles on the joint performance.
基金This work was supported by the National Natural Science Foundation of China under Grant No.60873068,61472169 the Program for Excellent Talents in Liaoning Province under Grant No.LR201017.
文摘Multi-way join is critical for many big data applications such as data mining and knowledge discovery. Even though lots of research have been devoted to processing multi-way joins using MapReduce, there are still several problems in general to be further improved, such as transferring numerous unpromising intermediate data and lacking of better coordination mechanisms. This work proposes an efficient multi-way joins processing model using MapReduce, named Sharing-Coordination-MapReduce (SC-MapReduce), which has the functions of sharing and coordination. Our SC-MapReduce model can filter the unpromising intermediatedata largely by using the sharing mechanism and optimize the multiple tasks coordination of multi-way joins. Extensive experiments show that the proposed model is efficient, robust and scalable.
文摘On July 1, 1997, Hong Kong finally returns to the motherland. July 1 was a day of Chinese national pride. Looking back, Hong Kong experienced great changes and the Chinese nation was subjected to humiliation during the 156 years. The Chinese nation had expected and made unremitting efforts to become stronger for more than 100 years. After resuming sovereignty over Hong Kong, the Chinese government will bring a brighter future to Hong Kong under the policies of "one country, two systems," and "Hong Kong people governing Hong Kong, with a high degree of autonomy." Hong Kong and the mainland will conduct more economic and cultural exchanges and create a more splendid future for the motherland.
文摘Zhao Xianming, a narcotics control liaison officer for Mengla county in southwest China＇s Yunnan Province,clearly remembered the circumstances of that Saturday.
文摘As the data managed by applications has evolved over the years with the arrival of Web 2.0,a large number of new databases have been developed to manage various types of data.While the traditional relational databases continue to exist,NoSQL databases which are document oriented or key-value stores or columnar continue to evolve and are embraced very rapidly across the industry.It is not just the type of data handled by these databases that is different but also the query language they use is also different.This paper talks about a uniform query framework that can be used for traditional relational databases and NoSQL databases.This query framework can also perform joins,aggregates,filter on data from various data sources in a single query.
文摘China＇s arduous war against the HIV/AIDS plague gained a powerful new warrior when the State Industry ＆ Commerce Administration （SICA） integrated an HIV prevention message into its routine duties.
