Collaborative Filtering (CF) technique has proved to be one of the most successful techniques in recommendation systems in recent years. However, traditional centralized CF system has suffered from its limited scalabi...Collaborative Filtering (CF) technique has proved to be one of the most successful techniques in recommendation systems in recent years. However, traditional centralized CF system has suffered from its limited scalability as calculation complexity increases rapidly both in time and space when the record in the user database increases. Peer-to-peer (P2P) network has attracted much attention because of its advantage of scalability as an alternative architecture for CF systems. In this paper, authors propose a decentralized CF algorithm, called PipeCF, based on distributed hash table (DHT) method which is the most popular P2P routing algorithm because of its efficiency, scalability, and robustness. Authors also propose two novel approaches: significance refinement (SR) and unanimous amplification (UA), to improve the scalability and prediction accuracy of DHT-based CF algorithm. The experimental data show that our DHT-based CF system has better prediction accuracy, efficiency and scalability than traditional CF systems.展开更多
The project for commercial application of the silver catalyst YS-9010 at the Shanghai Petrochemical Company has passed the appraisal.The experts attending the appraisal meeting have unanimously recognized that this te...The project for commercial application of the silver catalyst YS-9010 at the Shanghai Petrochemical Company has passed the appraisal.The experts attending the appraisal meeting have unanimously recognized that this test has made a breakthrough to attain a catalytic selectivity of 90%along with providing a technology to quickly increase the catalyst selectivity and shorten the acclimation period,making the comprehensive performance of this catalyst comparable to the international advanced level.展开更多
The question on the lips of African football players and fans,and especially administrators at the Confederation of African Football (CAF),is where will the 2019 Africa Cup of Nations (CAN)be held?One thing is sure:Sc...The question on the lips of African football players and fans,and especially administrators at the Confederation of African Football (CAF),is where will the 2019 Africa Cup of Nations (CAN)be held?One thing is sure:Scheduled from June 15 to July 13,2019,it will not be held in Cameroon.After bitter discussions lasting nearly 10 hours at the CAF General Assembly,which took place on November 30,2018,in Accra,Ghana,members of CAF's Executive Committee unanimously decided to strip Cameroon from its hosting rights for this major African football event.展开更多
Global environmental meeting, legislating a reduction in the emission of greenhouse gases for planet earth, is what mankind now hopes for, having realized the enormous dangers in the process of climate change. Global ...Global environmental meeting, legislating a reduction in the emission of greenhouse gases for planet earth, is what mankind now hopes for, having realized the enormous dangers in the process of climate change. Global warming is no longer denied by the so-called cornucopians （e.g. Lomberg）, but global policy-making originating in reunions of 190 governments or more stumble on collective action difficulties, spelled out in game theory. Paris will not succeed where Copenhagen failed, namely to arrive at a binding and enforceable global environment policy that will be implemented before it is too late. Instead, there will be massive transaction costs from negotiating and re-negotiating, endless voting, the making of promises exante and reneging ex post, as well as the futile attempts at any enforcement action, given state sovereignty. Mankind will have to learn how to cope with the outcomes of global warming, as resilience is the only hope.展开更多
文摘Collaborative Filtering (CF) technique has proved to be one of the most successful techniques in recommendation systems in recent years. However, traditional centralized CF system has suffered from its limited scalability as calculation complexity increases rapidly both in time and space when the record in the user database increases. Peer-to-peer (P2P) network has attracted much attention because of its advantage of scalability as an alternative architecture for CF systems. In this paper, authors propose a decentralized CF algorithm, called PipeCF, based on distributed hash table (DHT) method which is the most popular P2P routing algorithm because of its efficiency, scalability, and robustness. Authors also propose two novel approaches: significance refinement (SR) and unanimous amplification (UA), to improve the scalability and prediction accuracy of DHT-based CF algorithm. The experimental data show that our DHT-based CF system has better prediction accuracy, efficiency and scalability than traditional CF systems.
文摘The project for commercial application of the silver catalyst YS-9010 at the Shanghai Petrochemical Company has passed the appraisal.The experts attending the appraisal meeting have unanimously recognized that this test has made a breakthrough to attain a catalytic selectivity of 90%along with providing a technology to quickly increase the catalyst selectivity and shorten the acclimation period,making the comprehensive performance of this catalyst comparable to the international advanced level.
文摘The question on the lips of African football players and fans,and especially administrators at the Confederation of African Football (CAF),is where will the 2019 Africa Cup of Nations (CAN)be held?One thing is sure:Scheduled from June 15 to July 13,2019,it will not be held in Cameroon.After bitter discussions lasting nearly 10 hours at the CAF General Assembly,which took place on November 30,2018,in Accra,Ghana,members of CAF's Executive Committee unanimously decided to strip Cameroon from its hosting rights for this major African football event.
文摘Global environmental meeting, legislating a reduction in the emission of greenhouse gases for planet earth, is what mankind now hopes for, having realized the enormous dangers in the process of climate change. Global warming is no longer denied by the so-called cornucopians （e.g. Lomberg）, but global policy-making originating in reunions of 190 governments or more stumble on collective action difficulties, spelled out in game theory. Paris will not succeed where Copenhagen failed, namely to arrive at a binding and enforceable global environment policy that will be implemented before it is too late. Instead, there will be massive transaction costs from negotiating and re-negotiating, endless voting, the making of promises exante and reneging ex post, as well as the futile attempts at any enforcement action, given state sovereignty. Mankind will have to learn how to cope with the outcomes of global warming, as resilience is the only hope.
