Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance sc...Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.展开更多
Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) tec...Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.展开更多
The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . T...The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.展开更多
A new scheduling algorithm, which aims to provide proportional and controllable QoS (Quality of Service) in terms of burst loss probability for OBS (Optical Burst Switching) networks, is proposed on the ba- sis of a s...A new scheduling algorithm, which aims to provide proportional and controllable QoS (Quality of Service) in terms of burst loss probability for OBS (Optical Burst Switching) networks, is proposed on the ba- sis of a survey of QoS schemes in current OBS networks. With simulations, performance analysis and com- parisons are carried out in detail. The results show that, in the proposed scheme, burst loss probabilities are proportional to the given factors and the control of QoS performance can be achieved with better performance. This scheme will be beneficial to the OBS network management and the tariff policy making.展开更多
Fault detection in optical burst switching （OBS） networks will be a challenging task in the future. A novel mechanism based on probe burst （PB） and a new key concept is proposed to detect faults of OBS networks by...Fault detection in optical burst switching （OBS） networks will be a challenging task in the future. A novel mechanism based on probe burst （PB） and a new key concept is proposed to detect faults of OBS networks by sampling the health of data channels, which solve the difficulty of optical monitoring schemes while keeps the transparency of data network to Internet protocol （IP） packets. It takes full advantage of the characteristics of OBS, including architecture and signalling scheme, and introduces the excellent performances of single-hop-test used in electrical communication networks into OBS environment while avoids the shortcoming that any optical burst must undergo an optical-electric-optical （OEO） conversion. Well designed PB can provide exact criterion for judging whether protection/restoration should be excuted according to hard or soft fault identification.展开更多
目的检测肥胖大鼠网膜脂肪组织KLF4及KLF7 m RNA表达水平,分析其与炎症的相关性。方法 Wistar健康雄性大鼠高脂喂养,诱导肥胖模型。高脂喂养后第4、10周检测大鼠血脂、血糖水平;ELISA法测定血浆中TNF-α、LPT、APN水平;10周后,q RT-PCR...目的检测肥胖大鼠网膜脂肪组织KLF4及KLF7 m RNA表达水平,分析其与炎症的相关性。方法 Wistar健康雄性大鼠高脂喂养,诱导肥胖模型。高脂喂养后第4、10周检测大鼠血脂、血糖水平;ELISA法测定血浆中TNF-α、LPT、APN水平;10周后,q RT-PCR法检测网膜脂肪组织KLF4、KLF7及NF-κB炎症信号通路关键因子m RNA表达水平。结果高脂喂养4周后,实验组大鼠体质量开始显著高于对照组,第10周实验组大鼠体质量进入平台期,但仍高于对照组(P<0.05)。高脂喂养第4及第10周,实验组大鼠血浆FFA、Glu、TG、TC、LDL、TNF-α水平高于对照组,LPT、APN水平低于对照组(P<0.05)。网膜脂肪组织中,实验组TLR9、KLF4 m RNA表达水平低于对照组,KLF7、SRC和IL-6 m RNA表达水平高于对照组;TLR9与血浆FFA负相关,与KLF4正相关;KLF4与SRC、NF-κB负相关;KLF7与TLR4、SRC、NF-κB和IL-6正相关,与KLF4负相关(P<0.05)。结论肥胖状态下,高水平的FFA一方面可与TLR4结合上调KLF7表达,促进炎症因子表达,导致释放组织发生炎症;同时,可抑制TLR9水平而下调KLF4表达,减弱KLF4对炎症信号通路关键因子的抑制作用,从而促进炎症反应。展开更多
基金supported by the National Natural Science Foundation of China(No.60572050)the National High Technology Research and Development Programme of China(No.2008AA01Z211)
文摘Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.
基金Founded by the National Natural Science Foundation of China (No.60502005).
文摘Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.
基金Project(60632010) supported by the National Natural Science Foundation of China
文摘The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.
基金Supported by National Key Project of 863 Program of China (No.2002AA122021), Scientific Research Fund of Chongqing Municipal Education Commission (No.040504 and KJ050504), and Chongqing Science and Technology Commission (CSTC, 2005BB2066).
文摘A new scheduling algorithm, which aims to provide proportional and controllable QoS (Quality of Service) in terms of burst loss probability for OBS (Optical Burst Switching) networks, is proposed on the ba- sis of a survey of QoS schemes in current OBS networks. With simulations, performance analysis and com- parisons are carried out in detail. The results show that, in the proposed scheme, burst loss probabilities are proportional to the given factors and the control of QoS performance can be achieved with better performance. This scheme will be beneficial to the OBS network management and the tariff policy making.
基金Supported by the National Natural Science Foundation of China （ No. 90304004）, High Technology Research and Development Program of China （ No 2005AA122310）, the Projects of the Science and Technology Council of Chongqing （2005BB2062, 2005AC2089）.
文摘Fault detection in optical burst switching （OBS） networks will be a challenging task in the future. A novel mechanism based on probe burst （PB） and a new key concept is proposed to detect faults of OBS networks by sampling the health of data channels, which solve the difficulty of optical monitoring schemes while keeps the transparency of data network to Internet protocol （IP） packets. It takes full advantage of the characteristics of OBS, including architecture and signalling scheme, and introduces the excellent performances of single-hop-test used in electrical communication networks into OBS environment while avoids the shortcoming that any optical burst must undergo an optical-electric-optical （OEO） conversion. Well designed PB can provide exact criterion for judging whether protection/restoration should be excuted according to hard or soft fault identification.
文摘目的检测肥胖大鼠网膜脂肪组织KLF4及KLF7 m RNA表达水平,分析其与炎症的相关性。方法 Wistar健康雄性大鼠高脂喂养,诱导肥胖模型。高脂喂养后第4、10周检测大鼠血脂、血糖水平;ELISA法测定血浆中TNF-α、LPT、APN水平;10周后,q RT-PCR法检测网膜脂肪组织KLF4、KLF7及NF-κB炎症信号通路关键因子m RNA表达水平。结果高脂喂养4周后,实验组大鼠体质量开始显著高于对照组,第10周实验组大鼠体质量进入平台期,但仍高于对照组(P<0.05)。高脂喂养第4及第10周,实验组大鼠血浆FFA、Glu、TG、TC、LDL、TNF-α水平高于对照组,LPT、APN水平低于对照组(P<0.05)。网膜脂肪组织中,实验组TLR9、KLF4 m RNA表达水平低于对照组,KLF7、SRC和IL-6 m RNA表达水平高于对照组;TLR9与血浆FFA负相关,与KLF4正相关;KLF4与SRC、NF-κB负相关;KLF7与TLR4、SRC、NF-κB和IL-6正相关,与KLF4负相关(P<0.05)。结论肥胖状态下,高水平的FFA一方面可与TLR4结合上调KLF7表达,促进炎症因子表达,导致释放组织发生炎症;同时,可抑制TLR9水平而下调KLF4表达,减弱KLF4对炎症信号通路关键因子的抑制作用,从而促进炎症反应。
