This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with M...This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with Markov chains or supermartingales. Then the drift conditions which guarantee the convergence of evolutionary algorithms are described. And next the drift conditions which are used to estimate the hitting times of evolutionary algorithms are presented. Finally an example is given to show how to analyse hitting times of EAs by drift analysis approach.展开更多
There are three parts in this article.In Section 1,we establish the model of branching chain with drift in space-time random environment(BCDSTRE),i.e.,the coupling of branching chain and random walk.In Section 2,we pr...There are three parts in this article.In Section 1,we establish the model of branching chain with drift in space-time random environment(BCDSTRE),i.e.,the coupling of branching chain and random walk.In Section 2,we prove that any BCDSTRE must be a Markov chain in time random environment when we consider the distribution of the particles in space as a random element.In Section 3,we calculate the first-order moments and the second-order moments of BCDSTRE.展开更多
This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the...This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the satellite orbit design and the orbit injection deviation are the causes for the initial shift velocity, whereas the atmospheric drag and the sun gravitational perturbation produce the shift acceleration. To deal with these shift factors, a shift control method is put forward, through such methods as orbit variation design, orbit altitude, and inclination keeping control. The simulation experiment and practical application have proved the effectiveness of this control method.展开更多
The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have the...The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper.At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP).展开更多
A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field-programmable gate array and high-speed PCI extensions for instrumentation platfor...A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field-programmable gate array and high-speed PCI extensions for instrumentation platform, the digital integrator has realized octal-channel10-k Hz real-time integration and data transmission. In order to reduce the integration drift, a 24-bit analog-todigital converter and simple analog processing circuits are applied for high-precision sampling, while certain correction algorithms are used to minimize the drift. With simple and highly integrated circuits and high-performance digital processor, the digital integrator is of high stability and functional expansibility which greatly simplifies the operation procedure. The digital integrator has been tested in the plasma discharge experiments, and the experimental results have confirmed that the drift performance and accuracy of the digital integrator could fully meet the requirements of HL-2A.展开更多
The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly co...The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly consists of two parts,i.e.,an analog electronics section(including a pre-amplifier,a signal shaper and filter,a constant fraction timing circuit,and a peak hold circuit)and a digital electronics section(including an ADC and a TDC).Test results with X-ray sources show that an energy dynamic range of 1-10 keV with an integral nonlinearity of less than 0.1%can be achieved,and the energy resolution is better than 160 eV @ 5.9 keV FWHM.Using a waveform generator,test results also indicate that time resolution of the electronics system is about 3.7 ns,which is much less than the transit time spread of SDD(<100 ns)and satisfies the requirements of future applications.展开更多
守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟...守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟进行分类,针对分类结果分别运用原子时尺度理论方法计算全氢钟时间尺度,并给出分析结果。随后计算全铯钟时间尺度,并分析探究两种不同的氢铯联合钟组时间尺度。结果表明,基于频率漂移量较小的氢钟组形成的时间尺度波动范围小,且稳定度优于频率漂移量较大的氢钟组形成的时间尺度。氢铯联合形成的时间尺度稳定度优于全铯钟时间尺度,不同的氢铯联合钟组计算得到的时间尺度结果相近。展开更多
针对现有序列推荐模型忽略了不同用户的个性化行为,导致模型不能充分捕获用户动态偏好而产生的兴趣漂移等问题,提出了一种基于用户长短期偏好的序列推荐模型(Sequential Recommendation Model Based on User’s Long and Short Term Pre...针对现有序列推荐模型忽略了不同用户的个性化行为,导致模型不能充分捕获用户动态偏好而产生的兴趣漂移等问题,提出了一种基于用户长短期偏好的序列推荐模型(Sequential Recommendation Model Based on User’s Long and Short Term Preference,ULSP-SRM)。首先,根据用户的序列中交互物品的类别和时间信息生成用户的动态类别嵌入,进而有效建立物品之间的关联性,并且降低数据的稀疏性;其次,根据用户当前点击物品和最后一项点击的时间间隔信息生成个性化时序位置嵌入矩阵,模拟用户的个性化聚集现象,以更好地反映用户偏好的动态变化;然后,将融合了个性化时序位置嵌入矩阵的用户长期偏好序列以会话为单位输入门控循环单元中,生成用户的长期偏好表示,并通过注意力机制将用户长短期偏好进行融合,生成用户的最终偏好表示,从而达到充分捕获用户偏好的目的;最后,将用户最终偏好表示输入推荐预测层进行下一项推荐预测。在Amazon公开数据集的7个子集上进行实验,采用AUC(Area Under Curve)值、召回率和精确率指标进行综合评估,实验结果表明,所提模型的表现优于其他先进基准模型,有效地提升了推荐性能。展开更多
基金Supported by Engineering and Physical Science Research Courcil(GR/R52541/01)and State Laboratory of Software Engineering at Wuhan University
文摘This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with Markov chains or supermartingales. Then the drift conditions which guarantee the convergence of evolutionary algorithms are described. And next the drift conditions which are used to estimate the hitting times of evolutionary algorithms are presented. Finally an example is given to show how to analyse hitting times of EAs by drift analysis approach.
基金Supported by the NSFC(10371092,11771185,10871200)
文摘There are three parts in this article.In Section 1,we establish the model of branching chain with drift in space-time random environment(BCDSTRE),i.e.,the coupling of branching chain and random walk.In Section 2,we prove that any BCDSTRE must be a Markov chain in time random environment when we consider the distribution of the particles in space as a random element.In Section 3,we calculate the first-order moments and the second-order moments of BCDSTRE.
基金supported by the China Postdotoral Science Foundation(20060401004)
文摘This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the satellite orbit design and the orbit injection deviation are the causes for the initial shift velocity, whereas the atmospheric drag and the sun gravitational perturbation produce the shift acceleration. To deal with these shift factors, a shift control method is put forward, through such methods as orbit variation design, orbit altitude, and inclination keeping control. The simulation experiment and practical application have proved the effectiveness of this control method.
文摘The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper.At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP).
基金supported by National Natural Science Foundation of China(No.11375195)National Magnetic Confinement Fusion Energy Development Research(No.2013GB104003)
文摘A novel full-digital integrator has been developed for the magnetic diagnostics in HL-2A. Based on the pipeline processing of the field-programmable gate array and high-speed PCI extensions for instrumentation platform, the digital integrator has realized octal-channel10-k Hz real-time integration and data transmission. In order to reduce the integration drift, a 24-bit analog-todigital converter and simple analog processing circuits are applied for high-precision sampling, while certain correction algorithms are used to minimize the drift. With simple and highly integrated circuits and high-performance digital processor, the digital integrator is of high stability and functional expansibility which greatly simplifies the operation procedure. The digital integrator has been tested in the plasma discharge experiments, and the experimental results have confirmed that the drift performance and accuracy of the digital integrator could fully meet the requirements of HL-2A.
基金supported by the National Natural Science Foundation of China(Grant No.11205154)
文摘The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly consists of two parts,i.e.,an analog electronics section(including a pre-amplifier,a signal shaper and filter,a constant fraction timing circuit,and a peak hold circuit)and a digital electronics section(including an ADC and a TDC).Test results with X-ray sources show that an energy dynamic range of 1-10 keV with an integral nonlinearity of less than 0.1%can be achieved,and the energy resolution is better than 160 eV @ 5.9 keV FWHM.Using a waveform generator,test results also indicate that time resolution of the electronics system is about 3.7 ns,which is much less than the transit time spread of SDD(<100 ns)and satisfies the requirements of future applications.
基金Supported by the Natural Science Research Foundation of Education Department of Guizhou Province(20090080,2010076)Supported by the Project of Kaili University(Z1004)Supported by the Key Discipline Construction Program of Kaili University(KZD2009001)
文摘守时型原子钟主要包括氢原子钟和铯原子钟,为进一步探究不同类型守时原子钟计算时间尺度相关性能,本文开展全氢钟及氢铯联合时间尺度研究。首先依据国际权度局(Bureau International des Poids et Mesures,BIPM)发布的d公报将氢原子钟进行分类,针对分类结果分别运用原子时尺度理论方法计算全氢钟时间尺度,并给出分析结果。随后计算全铯钟时间尺度,并分析探究两种不同的氢铯联合钟组时间尺度。结果表明,基于频率漂移量较小的氢钟组形成的时间尺度波动范围小,且稳定度优于频率漂移量较大的氢钟组形成的时间尺度。氢铯联合形成的时间尺度稳定度优于全铯钟时间尺度,不同的氢铯联合钟组计算得到的时间尺度结果相近。
文摘针对现有序列推荐模型忽略了不同用户的个性化行为,导致模型不能充分捕获用户动态偏好而产生的兴趣漂移等问题,提出了一种基于用户长短期偏好的序列推荐模型(Sequential Recommendation Model Based on User’s Long and Short Term Preference,ULSP-SRM)。首先,根据用户的序列中交互物品的类别和时间信息生成用户的动态类别嵌入,进而有效建立物品之间的关联性,并且降低数据的稀疏性;其次,根据用户当前点击物品和最后一项点击的时间间隔信息生成个性化时序位置嵌入矩阵,模拟用户的个性化聚集现象,以更好地反映用户偏好的动态变化;然后,将融合了个性化时序位置嵌入矩阵的用户长期偏好序列以会话为单位输入门控循环单元中,生成用户的长期偏好表示,并通过注意力机制将用户长短期偏好进行融合,生成用户的最终偏好表示,从而达到充分捕获用户偏好的目的;最后,将用户最终偏好表示输入推荐预测层进行下一项推荐预测。在Amazon公开数据集的7个子集上进行实验,采用AUC(Area Under Curve)值、召回率和精确率指标进行综合评估,实验结果表明,所提模型的表现优于其他先进基准模型,有效地提升了推荐性能。
