Dense network coding(NC) is widely used in wireless cooperative downloading systems. Wireless devices have limited computing resources. Researchers have recently found that dense NC is not suitable because of its high...Dense network coding(NC) is widely used in wireless cooperative downloading systems. Wireless devices have limited computing resources. Researchers have recently found that dense NC is not suitable because of its high coding complexity, and it is necessary to use chunked NC in wireless environments. However, chunked NC can cause more communications, and the amount of communications is affected by the chunk size. Therefore, setting a suitable chunk size to improve the overall performance of chunked NC is a prerequisite for applying it in wireless cooperative downloading systems. Most of the existing studies on chunked NC focus on centralized wireless broadcasting systems, which are different from wireless cooperative downloading systems with distributed features. Accordingly, we study the performance of chunked NC based wireless cooperative downloading systems. First, an analysis model is established using a Markov process taking the distributed features into consideration, and then the block collection completion time of encoded blocks for cooperative downloading is optimized based on the analysis model. Furthermore, queuing theory is used to model the decoding process of the chunked NC. Combining queuing theory with the analysis model, the decoding completion time for cooperative downloading is optimized, and the optimal chunk size is derived. Numerical simulation shows that the block collection completion time and the decode completion time can be largely reduced after optimization.展开更多
This study is to examine the effects of some significant factors on consumers' willingness to pay( WTP) for digital music via the moderating variables of music affinity and the deterrence effect of the legislation...This study is to examine the effects of some significant factors on consumers' willingness to pay( WTP) for digital music via the moderating variables of music affinity and the deterrence effect of the legislation. Based on 517 Chinese respondents with access to digital music,using the multiple liner regression model,this study indicates that free ideology,perceived benefits of free downloading,perceived benefits of paid downloading,subjective norm,habit strength have direct influence on WTP,and music affinity and the deterrence effect of the legislation have moderating effects. This study contributes theoretically to research on Chinese consumers' WTP for digital music and offers practical recommendations for the digital music charging system setup.展开更多
With the emergence and further development of the digital library, the approaches of information acquisition correspondingly change a lot. This paper makes a statistical analysis on the journal downloading and citatio...With the emergence and further development of the digital library, the approaches of information acquisition correspondingly change a lot. This paper makes a statistical analysis on the journal downloading and citation behaviors under the digital environment conceived by the National Science Library(NSL), Chinese Academy of Sciences(CAS). It can be seen that the development of digital resources has influenced scientific research behaviors. For example, the large quantity of full-text downloading will maintain; the trend of journal downloading behaviors is basically same as the journal citation behavior; journals with large quantity of full-text downloading also boast the high cited times, and vice versa. Furthermore, authors make a linear regression analysis, with the journal downloading amount as the independent variable and journal cited times as dependent variable. Then they also prove the positive correlation between the journal downloading and citation behaviors by means of Pearson's correlation coefficient formula.展开更多
The recent advances in wireless communication technology enable high-speed vehicles to download data from roadside units(RSUs). However, the data download volume of individual vehicle is rather restricted due to high ...The recent advances in wireless communication technology enable high-speed vehicles to download data from roadside units(RSUs). However, the data download volume of individual vehicle is rather restricted due to high mobility and limited transmission range of vehicles, bringing users poor performance. To address this issue, we exploit the combination of both clustering and carry-and-forward schemes in this paper. Our scheme coordinates the cooperation of multiple infrastructures, cluster formation in the same direction and data forwarding of reverse vehicles to facilitate the target vehicle to download large-size content in dark areas. The process of data dissemination and achievable data download volume are then derived and analyzed theoretically. Finally, we conduct extensive simulations to verify the performance of the proposed scheme. Results show significant benefits of the proposed scheme in terms of increasing data download volume and throughput.展开更多
P4M(Positive Pulser Pulse Position Modulation)码是将测量数据信息利用脉冲信号之间的间隔时间的大小来表达的一种传输方式。主要从仪器的整个传输过程入手,仪器是如何把Sensor测量数据转化成脉冲信号,如何把接收的脉冲信号转化为Sen...P4M(Positive Pulser Pulse Position Modulation)码是将测量数据信息利用脉冲信号之间的间隔时间的大小来表达的一种传输方式。主要从仪器的整个传输过程入手,仪器是如何把Sensor测量数据转化成脉冲信号,如何把接收的脉冲信号转化为Sensor测量数据值,它们使用什么样的运算法则,以及怎样去通过DOWNLOAD菜单控制这个过程,及DOWNLOAD菜单的某些参数是如何设置的。展开更多
In peer-to-peer （P2P） video on demand （VoD） system, once the P2P downloading rate cannot satisfy the need of playback, server is quickly referred to for help in providing enough bandwidth. Thus the switch of downl...In peer-to-peer （P2P） video on demand （VoD） system, once the P2P downloading rate cannot satisfy the need of playback, server is quickly referred to for help in providing enough bandwidth. Thus the switch of downloading from other peers （P2P） and server （HTTP） exists. This paper uses the proportion of P2P downloading amount （PPDA） during the video watching process to measure server load. This article is interested in finding a better strategy or switch rule between P2P and HTTP downloading for saving server bandwidth. The authors suggest and model a kind of switch rule based on local buffer amount, using mathematical theory of Brownian motion. It can effectively alleviate the impact of P2P rate fluctuation, reduce the switch times and improve the PPDA by at least 3%-5% on the basis of the former switch rule, which means substantial cost can be saved. Particularly the PPDA is related with the ratio of playback bit rate to the HTTP downloading rate which means the PPDA can be restricted by controlling the ratio in the real-world system. Though the result comes from constant bit rate （CBR） video supposition, it provides perspective and method for variable bit rate （VBR） application, and valuable insights for the future development of P2P VoD system.展开更多
Communication is important for providing intelligent services in connected vehicles.Vehicles must be able to communicate with different places and exchange information while driving.For service operation,connected veh...Communication is important for providing intelligent services in connected vehicles.Vehicles must be able to communicate with different places and exchange information while driving.For service operation,connected vehicles frequently attempt to download large amounts of data.They can request data downloading to a road side unit(RSU),which provides infrastructure for connected vehicles.The RSU is a data bottleneck in a transportation system because data traffic is concentrated on the RSU.Therefore,it is not appropriate for a connected vehicle to always attempt a high speed download from the RSU.If the mobile network between a connected vehicle and an RSU has poor connection quality,the efficiency and speed of the data download from the RSU is decreased.This problem affects the quality of the user experience.Therefore,it is important for a connected vehicle to connect to an RSU with consideration of the network conditions in order to try to maximize download speed.The proposed method maximizes download speed from an RSU using a machine learning algorithm.To collect and learn from network data,fog computing is used.A fog server is integrated with the RSU to perform computing.If the algorithm recognizes that conditions are not good for mass data download,it will not attempt to download at high speed.Thus,the proposed method can improve the efficiency of high speed downloads.This conclusion was validated using extensive computer simulations.展开更多
In May 2008, ScienceWatch.com named Advances in Atmospheric Sciences a Rising Star among Geosciences journals. According to Essential Science IndicatorsSM from Thomson Reuters, the journal＇s cur-rent citation record ...In May 2008, ScienceWatch.com named Advances in Atmospheric Sciences a Rising Star among Geosciences journals. According to Essential Science IndicatorsSM from Thomson Reuters, the journal＇s cur-rent citation record includes 764 papers cited a total of 1,658 times between January 1, 1998 and February 29 2008.展开更多
In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that...In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that these two components are sufficient for specifying an open streaming architecture. The client selects appropriate chunks from the MP4 file to be transferred based on (1) the header information (i.e. the 'moov' box) in the first part of the file and (2) his observation of network throughput. The framework is completely client driven which allows for better server scalability and reduces signalling overhead. We discuss architecture and implementation issues such as complexity, interoperability and scalability and compare to 3GPP PSS Re1-6 adaptive streaming when appropriate. Measurements from a simple MP4/HTTP streaming client are presented showing that appropriate chunks are selected such that increased reliability is achieved.展开更多
[ Objective] The research aimed to analyze formation reason of a gale induced by Bohai Sea cyclone. [ Method] Yantai buoy station and Jimu Island automatic station were selected as reference of the actual situation. G...[ Objective] The research aimed to analyze formation reason of a gale induced by Bohai Sea cyclone. [ Method] Yantai buoy station and Jimu Island automatic station were selected as reference of the actual situation. Gale weather process which occurred in Yantai during 26 -27 April, 2010 was analyzed. [ Result] This gale weather was caused by Bohai Sea cyclone. Upper strong cold air invaded, which promoted ground low pressure quickly developing and deepening into Bohai Sea cyclone. Momentum download effect of the upper wind made ground wind speed in- crease. In forecast process of the gale, weather online and Yantai Grapes model both had basic accurate forecasts to magnitude, direction and influ- ence system of the gale, especially to the wind field at 10 m. [Conclusion] This research provided reference basis for forecast of such gale in future.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61370212,61402127,and 61502118)
文摘Dense network coding(NC) is widely used in wireless cooperative downloading systems. Wireless devices have limited computing resources. Researchers have recently found that dense NC is not suitable because of its high coding complexity, and it is necessary to use chunked NC in wireless environments. However, chunked NC can cause more communications, and the amount of communications is affected by the chunk size. Therefore, setting a suitable chunk size to improve the overall performance of chunked NC is a prerequisite for applying it in wireless cooperative downloading systems. Most of the existing studies on chunked NC focus on centralized wireless broadcasting systems, which are different from wireless cooperative downloading systems with distributed features. Accordingly, we study the performance of chunked NC based wireless cooperative downloading systems. First, an analysis model is established using a Markov process taking the distributed features into consideration, and then the block collection completion time of encoded blocks for cooperative downloading is optimized based on the analysis model. Furthermore, queuing theory is used to model the decoding process of the chunked NC. Combining queuing theory with the analysis model, the decoding completion time for cooperative downloading is optimized, and the optimal chunk size is derived. Numerical simulation shows that the block collection completion time and the decode completion time can be largely reduced after optimization.
文摘This study is to examine the effects of some significant factors on consumers' willingness to pay( WTP) for digital music via the moderating variables of music affinity and the deterrence effect of the legislation. Based on 517 Chinese respondents with access to digital music,using the multiple liner regression model,this study indicates that free ideology,perceived benefits of free downloading,perceived benefits of paid downloading,subjective norm,habit strength have direct influence on WTP,and music affinity and the deterrence effect of the legislation have moderating effects. This study contributes theoretically to research on Chinese consumers' WTP for digital music and offers practical recommendations for the digital music charging system setup.
文摘With the emergence and further development of the digital library, the approaches of information acquisition correspondingly change a lot. This paper makes a statistical analysis on the journal downloading and citation behaviors under the digital environment conceived by the National Science Library(NSL), Chinese Academy of Sciences(CAS). It can be seen that the development of digital resources has influenced scientific research behaviors. For example, the large quantity of full-text downloading will maintain; the trend of journal downloading behaviors is basically same as the journal citation behavior; journals with large quantity of full-text downloading also boast the high cited times, and vice versa. Furthermore, authors make a linear regression analysis, with the journal downloading amount as the independent variable and journal cited times as dependent variable. Then they also prove the positive correlation between the journal downloading and citation behaviors by means of Pearson's correlation coefficient formula.
基金supported by the National Natural Science Foundation of China under Grant No.61571350Key Research and Development Program of Shaanxi(Contract No.2017KW-004,2017ZDXM-GY-022)the 111 Project(B08038)
文摘The recent advances in wireless communication technology enable high-speed vehicles to download data from roadside units(RSUs). However, the data download volume of individual vehicle is rather restricted due to high mobility and limited transmission range of vehicles, bringing users poor performance. To address this issue, we exploit the combination of both clustering and carry-and-forward schemes in this paper. Our scheme coordinates the cooperation of multiple infrastructures, cluster formation in the same direction and data forwarding of reverse vehicles to facilitate the target vehicle to download large-size content in dark areas. The process of data dissemination and achievable data download volume are then derived and analyzed theoretically. Finally, we conduct extensive simulations to verify the performance of the proposed scheme. Results show significant benefits of the proposed scheme in terms of increasing data download volume and throughput.
文摘P4M(Positive Pulser Pulse Position Modulation)码是将测量数据信息利用脉冲信号之间的间隔时间的大小来表达的一种传输方式。主要从仪器的整个传输过程入手,仪器是如何把Sensor测量数据转化成脉冲信号,如何把接收的脉冲信号转化为Sensor测量数据值,它们使用什么样的运算法则,以及怎样去通过DOWNLOAD菜单控制这个过程,及DOWNLOAD菜单的某些参数是如何设置的。
基金supported by PPLive company, and the National Basic Research Program of China (2007CB307101-1)the National Natural Science Foundation of China (60672069, 60772043)
文摘In peer-to-peer （P2P） video on demand （VoD） system, once the P2P downloading rate cannot satisfy the need of playback, server is quickly referred to for help in providing enough bandwidth. Thus the switch of downloading from other peers （P2P） and server （HTTP） exists. This paper uses the proportion of P2P downloading amount （PPDA） during the video watching process to measure server load. This article is interested in finding a better strategy or switch rule between P2P and HTTP downloading for saving server bandwidth. The authors suggest and model a kind of switch rule based on local buffer amount, using mathematical theory of Brownian motion. It can effectively alleviate the impact of P2P rate fluctuation, reduce the switch times and improve the PPDA by at least 3%-5% on the basis of the former switch rule, which means substantial cost can be saved. Particularly the PPDA is related with the ratio of playback bit rate to the HTTP downloading rate which means the PPDA can be restricted by controlling the ratio in the real-world system. Though the result comes from constant bit rate （CBR） video supposition, it provides perspective and method for variable bit rate （VBR） application, and valuable insights for the future development of P2P VoD system.
文摘Communication is important for providing intelligent services in connected vehicles.Vehicles must be able to communicate with different places and exchange information while driving.For service operation,connected vehicles frequently attempt to download large amounts of data.They can request data downloading to a road side unit(RSU),which provides infrastructure for connected vehicles.The RSU is a data bottleneck in a transportation system because data traffic is concentrated on the RSU.Therefore,it is not appropriate for a connected vehicle to always attempt a high speed download from the RSU.If the mobile network between a connected vehicle and an RSU has poor connection quality,the efficiency and speed of the data download from the RSU is decreased.This problem affects the quality of the user experience.Therefore,it is important for a connected vehicle to connect to an RSU with consideration of the network conditions in order to try to maximize download speed.The proposed method maximizes download speed from an RSU using a machine learning algorithm.To collect and learn from network data,fog computing is used.A fog server is integrated with the RSU to perform computing.If the algorithm recognizes that conditions are not good for mass data download,it will not attempt to download at high speed.Thus,the proposed method can improve the efficiency of high speed downloads.This conclusion was validated using extensive computer simulations.
文摘In May 2008, ScienceWatch.com named Advances in Atmospheric Sciences a Rising Star among Geosciences journals. According to Essential Science IndicatorsSM from Thomson Reuters, the journal＇s cur-rent citation record includes 764 papers cited a total of 1,658 times between January 1, 1998 and February 29 2008.
文摘In this paper we describe how progressive download and adaptive streaming can be combined into a simple and efficient streaming framework. Based on the MPEG-4 file format (MP4) we use HTTP for transport and argue that these two components are sufficient for specifying an open streaming architecture. The client selects appropriate chunks from the MP4 file to be transferred based on (1) the header information (i.e. the 'moov' box) in the first part of the file and (2) his observation of network throughput. The framework is completely client driven which allows for better server scalability and reduces signalling overhead. We discuss architecture and implementation issues such as complexity, interoperability and scalability and compare to 3GPP PSS Re1-6 adaptive streaming when appropriate. Measurements from a simple MP4/HTTP streaming client are presented showing that appropriate chunks are selected such that increased reliability is achieved.
文摘[ Objective] The research aimed to analyze formation reason of a gale induced by Bohai Sea cyclone. [ Method] Yantai buoy station and Jimu Island automatic station were selected as reference of the actual situation. Gale weather process which occurred in Yantai during 26 -27 April, 2010 was analyzed. [ Result] This gale weather was caused by Bohai Sea cyclone. Upper strong cold air invaded, which promoted ground low pressure quickly developing and deepening into Bohai Sea cyclone. Momentum download effect of the upper wind made ground wind speed in- crease. In forecast process of the gale, weather online and Yantai Grapes model both had basic accurate forecasts to magnitude, direction and influ- ence system of the gale, especially to the wind field at 10 m. [Conclusion] This research provided reference basis for forecast of such gale in future.
