The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process th...The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process that leads to a significant deterioration of non-uniformity when scaling up to larger areas.Since the performance of gaseous detectors is highly dependent on the choice of working gas,optimizing the gas mixture offers a promising solution to improve the uniformity performance.This paper addresses these challenges through a combined approach of simulation based on Garfield++and experimental studies.The simulation investigates the properties of different mixing fractions of gas mixtures and their impact on detector performance,including gain uniformity and time resolution.To verify the simulation results,experimental tests were conducted using a multi-channel PICOSEC MM prototype with different gas mixtures.The experimental results are consistent with the findings of the simulation,indicating that a higher concentration of neon significantly improves the detector’s gain uniformity.Furthermore,the influence of gas mixtures on time resolution was explored as a critical performance indicator.The study presented in this paper offers valuable insights for improving uniformity in large-area PICOSEC MM detectors and optimizing overall performance.展开更多
In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-...In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.展开更多
针对部分场景下标签较少、样本不均衡的时序数据,为了更好的捕捉序列之间的逐步依赖关系,本文一方面使用具有因果关系属性的时域卷积网络构建生成对抗网络,另一方面使用长短期记忆网络构建嵌入网络和复现网络,以实现模型同时处理短期依...针对部分场景下标签较少、样本不均衡的时序数据,为了更好的捕捉序列之间的逐步依赖关系,本文一方面使用具有因果关系属性的时域卷积网络构建生成对抗网络,另一方面使用长短期记忆网络构建嵌入网络和复现网络,以实现模型同时处理短期依存项和长期依存项,从而提出一种基于时域卷积网络和长短期记忆网络的时间序列生成对抗网络(A Time-series Generative Adversarial Network based on Temporal convolutional network and Long-short term memory network, TL-TimeGAN)。采用覆盖性、有用性和相似度检验的综合分析方法作为合成数据质量的评价指标,进一步全面地评价合成数据的覆盖性、预测程度和相似性。最终,基于以太坊欺诈检测数据集,使用Tabnet网络对扩增数据进行异常检测并获得局部特征重要性以及全局特征重要性,以增强扩增数据应用于实际工作的实践指导价值。展开更多
[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件...[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件下，引物SYBR2的扩增效率高于SYBR1。Mg^2＋的适宜浓度为2．0mg／L。Real Time PCR扩增产物具有良好的特异性，熔解曲线特异峰出现在84．5℃附近，在熔解曲线略低于83℃附近有极微弱的非特异峰。因此在定量反应中信号检测步骤应放在84℃。以4种不同模板分子数条件下扩增曲线Ct值得到的回归方程为Y=-3．78×log（copynumber）＋39．50，相关系数为0．998。[结论]该试验获得的Real Time PCR体系可用于转基因植株表达水平的检测。展开更多
近年来,科研论文的合著现象及其与论文影响力之间的关系受到广泛关注。本文以1997—2013年Financial Times TOP 45商学院国际期刊论文为研究对象,对作者数量与论文被引(高被引还是零被引)之间的关系进行实证研究,从论文影响力方面揭示...近年来,科研论文的合著现象及其与论文影响力之间的关系受到广泛关注。本文以1997—2013年Financial Times TOP 45商学院国际期刊论文为研究对象,对作者数量与论文被引(高被引还是零被引)之间的关系进行实证研究,从论文影响力方面揭示商学领域是否存在最佳科研合作规模。研究发现:①与单独作者相比,多作者合作对论文总被引频次具有显著的正向影响,而且多作者合作论文成为高被引的概率更高,而成为零被引的概率更低;②作者数量与论文总被引频次之间存在显著的倒U形关系;进一步研究发现,作者数量与高被引论文概率呈倒U形关系,而与零被引论文概率呈正U形关系,且转折点均约为3人,表明商学领域存在使论文成为高被引而避免成为零被引的最佳合作规模;③分时间阶段实证结果表明,基于高被引和零被引的论文最佳合作规模逐步由2~3人增加至3~4人。展开更多
基金supported by the National Natural Science Foundation of China(12125505).
文摘The PICOSEC Micromegas(MM)is a precise timing gaseous detector based on a Cherenkov radiator coupled with a semi-transparent photocathode and an MM amplifying structure.It features a two-stage amplification process that leads to a significant deterioration of non-uniformity when scaling up to larger areas.Since the performance of gaseous detectors is highly dependent on the choice of working gas,optimizing the gas mixture offers a promising solution to improve the uniformity performance.This paper addresses these challenges through a combined approach of simulation based on Garfield++and experimental studies.The simulation investigates the properties of different mixing fractions of gas mixtures and their impact on detector performance,including gain uniformity and time resolution.To verify the simulation results,experimental tests were conducted using a multi-channel PICOSEC MM prototype with different gas mixtures.The experimental results are consistent with the findings of the simulation,indicating that a higher concentration of neon significantly improves the detector’s gain uniformity.Furthermore,the influence of gas mixtures on time resolution was explored as a critical performance indicator.The study presented in this paper offers valuable insights for improving uniformity in large-area PICOSEC MM detectors and optimizing overall performance.
基金supported by the National Natural Science Foundation of China(U21B2028).
文摘In the existing impact time control guidance (ITCG) laws for moving-targets, the effects of time-varying velocity caused by aerodynamics and gravity cannot be effectively con-sidered. Therefore, an ITCG with field-of-view (FOV) constraints based on biased proportional navigation guidance (PNG) is developed in this paper. The remaining flight time (time-to-go) estimation method is derived considering aerodynamic force and gravity. The number of differential equations is reduced and the integration step is increased by changing the integral variable, which makes it possible to obtain time-to-go through integration. An impact time controller with FOV constraints is proposed by analyzing the influence of the biased term on time-to-go and FOV constraint. Then, numerical simulations are performed to verify the correctness and superiority of the method.
文摘针对部分场景下标签较少、样本不均衡的时序数据,为了更好的捕捉序列之间的逐步依赖关系,本文一方面使用具有因果关系属性的时域卷积网络构建生成对抗网络,另一方面使用长短期记忆网络构建嵌入网络和复现网络,以实现模型同时处理短期依存项和长期依存项,从而提出一种基于时域卷积网络和长短期记忆网络的时间序列生成对抗网络(A Time-series Generative Adversarial Network based on Temporal convolutional network and Long-short term memory network, TL-TimeGAN)。采用覆盖性、有用性和相似度检验的综合分析方法作为合成数据质量的评价指标,进一步全面地评价合成数据的覆盖性、预测程度和相似性。最终,基于以太坊欺诈检测数据集,使用Tabnet网络对扩增数据进行异常检测并获得局部特征重要性以及全局特征重要性,以增强扩增数据应用于实际工作的实践指导价值。
文摘[目的]为转基因番茄植株的高通量筛选奠定基础。[方法]利用CTAB法提取番茄叶片总RNA进行Real Time PCR扩增，分析转MI1、2基因的番茄植株表达水平的检测体系。[结果]提取RNA的A260／A280为1．78～1．88，RNA无明显降解。在严谨扩增条件下，引物SYBR2的扩增效率高于SYBR1。Mg^2＋的适宜浓度为2．0mg／L。Real Time PCR扩增产物具有良好的特异性，熔解曲线特异峰出现在84．5℃附近，在熔解曲线略低于83℃附近有极微弱的非特异峰。因此在定量反应中信号检测步骤应放在84℃。以4种不同模板分子数条件下扩增曲线Ct值得到的回归方程为Y=-3．78×log（copynumber）＋39．50，相关系数为0．998。[结论]该试验获得的Real Time PCR体系可用于转基因植株表达水平的检测。
文摘近年来,科研论文的合著现象及其与论文影响力之间的关系受到广泛关注。本文以1997—2013年Financial Times TOP 45商学院国际期刊论文为研究对象,对作者数量与论文被引(高被引还是零被引)之间的关系进行实证研究,从论文影响力方面揭示商学领域是否存在最佳科研合作规模。研究发现:①与单独作者相比,多作者合作对论文总被引频次具有显著的正向影响,而且多作者合作论文成为高被引的概率更高,而成为零被引的概率更低;②作者数量与论文总被引频次之间存在显著的倒U形关系;进一步研究发现,作者数量与高被引论文概率呈倒U形关系,而与零被引论文概率呈正U形关系,且转折点均约为3人,表明商学领域存在使论文成为高被引而避免成为零被引的最佳合作规模;③分时间阶段实证结果表明,基于高被引和零被引的论文最佳合作规模逐步由2~3人增加至3~4人。
