The prevalence of smart phone and improvement of wireless net promote the usage of crowdsourced live streaming,where individual users act as live streaming sources to broadcast themselves online. Characterizing the pe...The prevalence of smart phone and improvement of wireless net promote the usage of crowdsourced live streaming,where individual users act as live streaming sources to broadcast themselves online. Characterizing the performance and identifying its bottleneck in such systems can shed light on the system design and performance optimization. TCP performance of a commercial crowdsourced live streaming system is examined by analyzing packet-level traces collected at streaming servers. TCP stalls that heavily hurt the Qo E of user have been identified. In particular,the TCP stalls account for as much as 31. 6% of the flow completion time for upload flows and result in abandonment of upload on the corresponding channels. Stalls caused by timeout retransmissions are further dissected and timeout retransmission characteristics are revealed to be dependent on the video encoding methods. These findings provide new insights in crowdsourced live streaming systems and can guide designers to improve the TCP efficiency.展开更多
The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton eva...The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton evaporation channels.We only considered the case of evaporating one proton first and then n neutrons in this work,other cases were ignored due to the small cross-section.The production cross sections of unknown isotopes ^(290,291)Fl in ^(38)S+^(255)Es reaction are the highest compared with ^(50)Ti+^(243)Np and ^(54)Cr+^(239)Pa reactions,and the maximum cross sections are 1.1 and 15.1 pb,respectively.^(42)S+^(254)Es is a promising candidate to approach the island of stability as the radioactive beam facilities are upgraded in the future,and the production cross sections of ^(291−294)Fl in that reaction are estimated to be 3.2,6.0,4.0,and 0.1 pb,respectively.展开更多
The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks ...The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks between different apertures.In view of this,a new coding scheme using staggering repetition interval was proposed.The transmitting signals were constructed by repeating the two(or more) modulated codes using staggering repetition interval,and then allocated to and transmitted simultaneously among different apertures.The decoding process was based on the subsection-matched filter under the assistance of different matched filters for different apertures.At last the outputs of subsection-matched filtering were added together.Staggering changed the positions of cross-correlation(CC) peaks from coinciding,which resulted in an effective reduction of CC.Our theoretical analysis and simulations showed that,the coding scheme can be used to reduce cross-talk,and a good cross-talk reduction will be achieved if the staggering delay is kept in an appropriate range.展开更多
In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ...In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ultraweak luminescence detection system, and find the significant difference in the weight distributions of the decay rate for hUC-MSCs with high and low viabilities. Spectral discrimination of hUC-MSCs with high and low viabilities is thus carried out by comparing the DL kinetics parameters, including the initial intensity, the peak decay rate and the peak weight value. Our results show that the novel optical method for the viability diagnosis of hUC-MSCs has a promising prospect.展开更多
基金Supported by the National Basic Research Program of China(2012CB315801)the National Natural Science Foundation of China(No.6157060397)
文摘The prevalence of smart phone and improvement of wireless net promote the usage of crowdsourced live streaming,where individual users act as live streaming sources to broadcast themselves online. Characterizing the performance and identifying its bottleneck in such systems can shed light on the system design and performance optimization. TCP performance of a commercial crowdsourced live streaming system is examined by analyzing packet-level traces collected at streaming servers. TCP stalls that heavily hurt the Qo E of user have been identified. In particular,the TCP stalls account for as much as 31. 6% of the flow completion time for upload flows and result in abandonment of upload on the corresponding channels. Stalls caused by timeout retransmissions are further dissected and timeout retransmission characteristics are revealed to be dependent on the video encoding methods. These findings provide new insights in crowdsourced live streaming systems and can guide designers to improve the TCP efficiency.
文摘The feasibility of producing superheavy nuclei in proton evaporation channels was systematically studied within the dinuclear system(DNS)model.Due to the Z=114 proton-shell,one can synthesize Fl isotopes in proton evaporation channels.We only considered the case of evaporating one proton first and then n neutrons in this work,other cases were ignored due to the small cross-section.The production cross sections of unknown isotopes ^(290,291)Fl in ^(38)S+^(255)Es reaction are the highest compared with ^(50)Ti+^(243)Np and ^(54)Cr+^(239)Pa reactions,and the maximum cross sections are 1.1 and 15.1 pb,respectively.^(42)S+^(254)Es is a promising candidate to approach the island of stability as the radioactive beam facilities are upgraded in the future,and the production cross sections of ^(291−294)Fl in that reaction are estimated to be 3.2,6.0,4.0,and 0.1 pb,respectively.
基金Project (Nos.60772147 and 60871060) supported by the National Natural Science Foundation of China
文摘The increase of frame rate,though with the potential in a coded ultrasound system,is generally concomitant with the simultaneous transmission of a number of apertures,and in consequence leads to increased cross-talks between different apertures.In view of this,a new coding scheme using staggering repetition interval was proposed.The transmitting signals were constructed by repeating the two(or more) modulated codes using staggering repetition interval,and then allocated to and transmitted simultaneously among different apertures.The decoding process was based on the subsection-matched filter under the assistance of different matched filters for different apertures.At last the outputs of subsection-matched filtering were added together.Staggering changed the positions of cross-correlation(CC) peaks from coinciding,which resulted in an effective reduction of CC.Our theoretical analysis and simulations showed that,the coding scheme can be used to reduce cross-talk,and a good cross-talk reduction will be achieved if the staggering delay is kept in an appropriate range.
基金supported by the National Natural Science Foundation of China(Nos.60508004 and 60778043)the National High Technology Research and Development Program of China(No.2011AA030205)+1 种基金the Doctoral Fund of Ministry of Education of China(No.20110031110035)the Tianjin Municipal Science and Technology Commission(No.08ZCDFGX09400)
文摘In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells(hUC-MSCs) with photo-induced delayed luminescence(DL). We measure the DL decay kinetics of hUC-MSCs using an ultraweak luminescence detection system, and find the significant difference in the weight distributions of the decay rate for hUC-MSCs with high and low viabilities. Spectral discrimination of hUC-MSCs with high and low viabilities is thus carried out by comparing the DL kinetics parameters, including the initial intensity, the peak decay rate and the peak weight value. Our results show that the novel optical method for the viability diagnosis of hUC-MSCs has a promising prospect.
