Extendible hashing is an effective way to manage increasingly large file system metadata,but it suffers from low concurrency and lack of optimization for non-volatile memory(NVM).In this paper,a multilevel hash direct...Extendible hashing is an effective way to manage increasingly large file system metadata,but it suffers from low concurrency and lack of optimization for non-volatile memory(NVM).In this paper,a multilevel hash directory based on lazy expansion is designed to improve the concurrency and efficiency of extendible hashing,and a hash bucket management algorithm based on groups is presented to improve the efficiency of hash key management by reducing the size of the hash bucket,thereby improving the performance of extendible hashing.Meanwhile,a hierarchical storage strategy of extendible hashing for NVM is given to take advantage of dynamic random access memory(DRAM)and NVM.Furthermore,on the basis of the device driver for Intel Optane DC Persistent Memory,the prototype of high-concurrency extendible hashing named NEHASH is implemented.Yahoo cloud serving benchmark(YCSB)is used to test and compare with CCEH,level hashing,and cuckoo hashing.The results show that NEHASH can improve read throughput by up to 16.5%and write throughput by 19.3%.展开更多
储能集装箱是锂电池储能电站的核心设备,每个集装箱由数千只电芯串并联构成。因此,对集装箱电芯锂电池荷电状态(state of charge,SOC)的准确估计成为表征储能电站运行最核心最基础的参数,并且为辅助新能源高效并网,储能系统的工作状态...储能集装箱是锂电池储能电站的核心设备,每个集装箱由数千只电芯串并联构成。因此,对集装箱电芯锂电池荷电状态(state of charge,SOC)的准确估计成为表征储能电站运行最核心最基础的参数,并且为辅助新能源高效并网,储能系统的工作状态也会相应地呈现随机性、波动性和不确定性,这对电芯状态估计的准确度提出了更高的要求。为此,首先基于基尔霍夫定律建立Thevenin电池模型,根据安时积分法列出系统的状态和观测方程,并且将其状态和观测方程作为扩展卡尔曼滤波(extended Kalman filtering,EKF)算法的研究对象。然后利用EKF算法对估计值电池SOC更新迭代,再将EKF算法中得到的卡尔曼矩阵和状态变量更新误差值以及UDDS工况下的电池数据,作为长短期记忆(long short-term memory,LSTM)神经网络算法的训练数据集,由此完成LSTM-EKF联合算法,实现对储能集装箱电芯SOC的优化估计。该文所提LSTM-EKF算法可将电芯SOC的误差值降低到1%以下。最后对优化算法在储能电站安全运行与监控平台中的应用情况进行介绍。展开更多
In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LST...In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LSTM) neural network is nested into the extended Kalman filter(EKF) to modify the Kalman gain such that the filtering performance is improved in the presence of large model uncertainties. To avoid the unstable network output caused by the abrupt changes of system states,an adaptive correction factor is introduced to correct the network output online. In the process of training the network, a multi-gradient descent learning mode is proposed to better fit the internal state of the system, and a rolling training is used to implement an online prediction logic. Based on the Lyapunov second method, we discuss the stability of the system, the result shows that when the training error of neural network is sufficiently small, the system is asymptotically stable. With its application to the estimation of time-varying parameters of a missile dual control system, the LSTM-EKF shows better filtering performance than the EKF and adaptive EKF(AEKF) when there exist large uncertainties in the system model.展开更多
Objective: To test the hypotheses that reading comprehension difficulties of adolescent students with ADHD: 1) are related not so much to weak verbal abilities or weak basic reading skills, as to impairments of workin...Objective: To test the hypotheses that reading comprehension difficulties of adolescent students with ADHD: 1) are related not so much to weak verbal abilities or weak basic reading skills, as to impairments of working memory and processing speed characteristic of ADHD;and 2) that extended time on a test of reading comprehension would yield significantly higher reading comprehension scores than would standard time. Method: Charts of 145 adolescents 13-18 years diagnosed with DSM-IV ADHD and no specific reading disorder after a comprehensive clinical and psycho-educational evaluation, were reviewed to extract 1) word reading and word attack subtest scores from the Woodcock-Johnson Achievement Test or the Wechsler Individual Achievement Test;2) Index scores from WISC-IV or WAIS-III IQ tests;3) scores from the Nelson-Denny Reading Test. Results: Mean index scores for verbal comprehension abilities not including reading were in the high average range, but working memory and processing speed index scores were significantly weaker. Under standard time limits 53% were unable to complete the reading comprehension test and only 42.8% were able to score within 1 SD of their IQ verbal comprehension index (VCI). When allowed extended time, 77.9% were able to score within 1 SD of their VCI. T-test comparisons between standard time and extended time were significant at < 0.001. Conclusions: Allowing extended time for adolescents with ADHD to complete tests involving reading may help to compensate for their impairments of working memory and processing speed, allowing them to score closer to their actual verbal abilities.展开更多
Shifting focus from the patient’s body to the healer’s body,this essay focuses on how Chinese physicians instrumentalized their bodies to heal(ie,body-as-technology)and their hands to think with(ie,hand-memory techn...Shifting focus from the patient’s body to the healer’s body,this essay focuses on how Chinese physicians instrumentalized their bodies to heal(ie,body-as-technology)and their hands to think with(ie,hand-memory techniques or simply,hand mnemonics).When physicians used their hands to memorize concepts related to clinical practice,calculate with time variables,and carry out ritual gestures intended to reduce risk,improve fortune,and even cure,their hands became extensions of their minds.This essay has three parts that follow the discovery process of the author’s research on hand-memory techniques found in Chinese medical texts.The first part“Divination and Revelation”explains the significance of how the author first learned about Chinese divination practices that used hand mnemonics.The second part“Original Frame”introduces the scholarship on arts of memory in Europe that informed interpretations of the earliest hand mnemonics found in Chinese medical texts.The third part“Expanded Frame”deploys some concepts from cognitive science to help situate Chinese medical hand mnemonics more broadly as an example of extended cognition.The essay concludes with an important distinction:sometimes Chinese healers’hands were used separately from their bodies to think through things and sometimes hand and body had to be integrated in order for the healer’s body-as-technology to act as a therapeutically effective instrument.展开更多
基金Project supported by the National Natural Science Foundation of China(No.61806086)the National Key R&D Program of China(No.2018YFB0804204)。
文摘Extendible hashing is an effective way to manage increasingly large file system metadata,but it suffers from low concurrency and lack of optimization for non-volatile memory(NVM).In this paper,a multilevel hash directory based on lazy expansion is designed to improve the concurrency and efficiency of extendible hashing,and a hash bucket management algorithm based on groups is presented to improve the efficiency of hash key management by reducing the size of the hash bucket,thereby improving the performance of extendible hashing.Meanwhile,a hierarchical storage strategy of extendible hashing for NVM is given to take advantage of dynamic random access memory(DRAM)and NVM.Furthermore,on the basis of the device driver for Intel Optane DC Persistent Memory,the prototype of high-concurrency extendible hashing named NEHASH is implemented.Yahoo cloud serving benchmark(YCSB)is used to test and compare with CCEH,level hashing,and cuckoo hashing.The results show that NEHASH can improve read throughput by up to 16.5%and write throughput by 19.3%.
文摘In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LSTM) neural network is nested into the extended Kalman filter(EKF) to modify the Kalman gain such that the filtering performance is improved in the presence of large model uncertainties. To avoid the unstable network output caused by the abrupt changes of system states,an adaptive correction factor is introduced to correct the network output online. In the process of training the network, a multi-gradient descent learning mode is proposed to better fit the internal state of the system, and a rolling training is used to implement an online prediction logic. Based on the Lyapunov second method, we discuss the stability of the system, the result shows that when the training error of neural network is sufficiently small, the system is asymptotically stable. With its application to the estimation of time-varying parameters of a missile dual control system, the LSTM-EKF shows better filtering performance than the EKF and adaptive EKF(AEKF) when there exist large uncertainties in the system model.
文摘Objective: To test the hypotheses that reading comprehension difficulties of adolescent students with ADHD: 1) are related not so much to weak verbal abilities or weak basic reading skills, as to impairments of working memory and processing speed characteristic of ADHD;and 2) that extended time on a test of reading comprehension would yield significantly higher reading comprehension scores than would standard time. Method: Charts of 145 adolescents 13-18 years diagnosed with DSM-IV ADHD and no specific reading disorder after a comprehensive clinical and psycho-educational evaluation, were reviewed to extract 1) word reading and word attack subtest scores from the Woodcock-Johnson Achievement Test or the Wechsler Individual Achievement Test;2) Index scores from WISC-IV or WAIS-III IQ tests;3) scores from the Nelson-Denny Reading Test. Results: Mean index scores for verbal comprehension abilities not including reading were in the high average range, but working memory and processing speed index scores were significantly weaker. Under standard time limits 53% were unable to complete the reading comprehension test and only 42.8% were able to score within 1 SD of their IQ verbal comprehension index (VCI). When allowed extended time, 77.9% were able to score within 1 SD of their VCI. T-test comparisons between standard time and extended time were significant at < 0.001. Conclusions: Allowing extended time for adolescents with ADHD to complete tests involving reading may help to compensate for their impairments of working memory and processing speed, allowing them to score closer to their actual verbal abilities.
基金International Consortium for Research in the Humanities(IKJF),University of Erlangen-Nürnberg(2011-2012,2014,2016)Elizabeth and J.Richardson Dilworth Fellow,Institute for Advanced Study,Princeton(2017-2018)+1 种基金National Endowment for Humanities Fellowship,US Government(2019)Visiting Scholar,Max Planck Institute for the History of Science,Berlin(2021-2022).
文摘Shifting focus from the patient’s body to the healer’s body,this essay focuses on how Chinese physicians instrumentalized their bodies to heal(ie,body-as-technology)and their hands to think with(ie,hand-memory techniques or simply,hand mnemonics).When physicians used their hands to memorize concepts related to clinical practice,calculate with time variables,and carry out ritual gestures intended to reduce risk,improve fortune,and even cure,their hands became extensions of their minds.This essay has three parts that follow the discovery process of the author’s research on hand-memory techniques found in Chinese medical texts.The first part“Divination and Revelation”explains the significance of how the author first learned about Chinese divination practices that used hand mnemonics.The second part“Original Frame”introduces the scholarship on arts of memory in Europe that informed interpretations of the earliest hand mnemonics found in Chinese medical texts.The third part“Expanded Frame”deploys some concepts from cognitive science to help situate Chinese medical hand mnemonics more broadly as an example of extended cognition.The essay concludes with an important distinction:sometimes Chinese healers’hands were used separately from their bodies to think through things and sometimes hand and body had to be integrated in order for the healer’s body-as-technology to act as a therapeutically effective instrument.
