能够提供更强计算能力的多核处理器将在安全关键系统中得到广泛应用,但是由于现代处理器所使用的流水线、乱序执行、动态分支预测、Cache等性能提高机制以及多核之间的资源共享,使得系统的最坏执行时间分析变得非常困难.为此,国际学术...能够提供更强计算能力的多核处理器将在安全关键系统中得到广泛应用,但是由于现代处理器所使用的流水线、乱序执行、动态分支预测、Cache等性能提高机制以及多核之间的资源共享,使得系统的最坏执行时间分析变得非常困难.为此,国际学术界提出时间可预测系统设计的思想,以降低系统的最坏执行时间分析难度.已有研究主要关注硬件层次及其编译方法的调整和优化,而较少关注软件层次,即,时间可预测多线程代码的构造方法以及到多核硬件平台的映射.提出一种基于同步语言模型驱动的时间可预测多线程代码生成方法,并对代码生成器的语义保持进行证明;提出一种基于AADL(architecture analysis and design language)的时间可预测多核体系结构模型,作为研究的目标平台;最后,给出多线程代码到多核体系结构模型的映射方法,并给出系统性质的分析框架.展开更多
This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in capti...This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in captive animals may lead them to respond with changes of the behavioral activities during the time prior to food deliveries which are referred to as food anticipatory activity. False killer whales at Qingdao Polar Ocean World(Qingdao, China) showed signifi cant variations of the rates of both the total sounds and sound classes(whistles, clicks, and burst pulses) around feedings. Precisely, from the Transition interval that recorded the lowest vocalization rate(3.40 s/m/d), the whales increased their acoustic emissions upon trainers' arrival(13.08 s/m/d). The high rate was maintained or intensifi ed throughout the food delivery(25.12 s/m/d), and then reduced immediately after the animals were fed(9.91 s/m/d). These changes in the false killer whales sound production rates around feeding times supports the hypothesis of the presence of a food anticipatory vocal activity. Although sound rates may not give detailed information regarding referential aspects of the animal communication it might still shed light about the arousal levels of the individuals during different social or environmental conditions. Further experiments should be performed to assess if variations of the time of feeding routines may affect the vocal activity of cetaceans in captivity as well as their welfare.展开更多
We model wireless local area network channel utilization over a finite interval through a finite time-horizon Markov(FTHM) model.By accurately capturing time-varying utilization,the FTHM model allows for generally dis...We model wireless local area network channel utilization over a finite interval through a finite time-horizon Markov(FTHM) model.By accurately capturing time-varying utilization,the FTHM model allows for generally distributed transmis-sion-opportunity(TXOP) duration,which most existing models do not account for.An absorbing state is introduced to limit the lifetime of the counting process,resulting in a non-ergodic Markov chain that is solved via transient analysis.The model predic-tions for time-varying utilization are validated by simulation with errors of no more than 0.1% after eight beacon intervals.Moreover,we show that the FTHM model prediction error is below 4% for Poisson distributed and uniformly distributed TXOP durations.展开更多
文摘能够提供更强计算能力的多核处理器将在安全关键系统中得到广泛应用,但是由于现代处理器所使用的流水线、乱序执行、动态分支预测、Cache等性能提高机制以及多核之间的资源共享,使得系统的最坏执行时间分析变得非常困难.为此,国际学术界提出时间可预测系统设计的思想,以降低系统的最坏执行时间分析难度.已有研究主要关注硬件层次及其编译方法的调整和优化,而较少关注软件层次,即,时间可预测多线程代码的构造方法以及到多核硬件平台的映射.提出一种基于同步语言模型驱动的时间可预测多线程代码生成方法,并对代码生成器的语义保持进行证明;提出一种基于AADL(architecture analysis and design language)的时间可预测多核体系结构模型,作为研究的目标平台;最后,给出多线程代码到多核体系结构模型的映射方法,并给出系统性质的分析框架.
基金Supported by grants from the Institute of Hydrobiology,Chinese Academy of Sciences
文摘This study examines whether a group of captive false killer whales(P seudorca crassidens) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in captive animals may lead them to respond with changes of the behavioral activities during the time prior to food deliveries which are referred to as food anticipatory activity. False killer whales at Qingdao Polar Ocean World(Qingdao, China) showed signifi cant variations of the rates of both the total sounds and sound classes(whistles, clicks, and burst pulses) around feedings. Precisely, from the Transition interval that recorded the lowest vocalization rate(3.40 s/m/d), the whales increased their acoustic emissions upon trainers' arrival(13.08 s/m/d). The high rate was maintained or intensifi ed throughout the food delivery(25.12 s/m/d), and then reduced immediately after the animals were fed(9.91 s/m/d). These changes in the false killer whales sound production rates around feeding times supports the hypothesis of the presence of a food anticipatory vocal activity. Although sound rates may not give detailed information regarding referential aspects of the animal communication it might still shed light about the arousal levels of the individuals during different social or environmental conditions. Further experiments should be performed to assess if variations of the time of feeding routines may affect the vocal activity of cetaceans in captivity as well as their welfare.
文摘We model wireless local area network channel utilization over a finite interval through a finite time-horizon Markov(FTHM) model.By accurately capturing time-varying utilization,the FTHM model allows for generally distributed transmis-sion-opportunity(TXOP) duration,which most existing models do not account for.An absorbing state is introduced to limit the lifetime of the counting process,resulting in a non-ergodic Markov chain that is solved via transient analysis.The model predic-tions for time-varying utilization are validated by simulation with errors of no more than 0.1% after eight beacon intervals.Moreover,we show that the FTHM model prediction error is below 4% for Poisson distributed and uniformly distributed TXOP durations.
