Chlorotrifluoroethylene(CTFE)is a vital fluorinated olefinic monomer produced through the catalytic hydrodechlorination of trichlorotrifluoroethane(CFC-113),an eco-friendly process.However,hydrodechlorination catalyst...Chlorotrifluoroethylene(CTFE)is a vital fluorinated olefinic monomer produced through the catalytic hydrodechlorination of trichlorotrifluoroethane(CFC-113),an eco-friendly process.However,hydrodechlorination catalysts for olefin production often suffer from poor stability.The Pd/AC catalyst and Pd-Cu/AC catalyst prepared by co-impregnation method exhibited poor stability,Pd-Cu/AC catalyst with CFC-113 conversion dropping to around 37%after 50 h of hydrodechlorination reaction.Brunauer-Emmett-Teller,transmission electron microscopy,X-ray photoelectron spectroscopy,and X-ray diffraction of fresh and deactivated Pd/AC catalysts indicate that the deactivation of Pd/AC catalysts is due to high-temperature agglomeration of Pd.Comparative analysis of fresh and deactivated Pd-Cu/AC catalysts using Brunauer-Emmett-Teller,transmission electron microscopy,and thermogravimetric analysis techniques revealed decreased dispersion of active sites,reduced surface area,catalyst aggregation deactivation,and a significant decrease in Cu content.Furthermore,the results of NH3-TPD revealed that the acid sites of the catalyst increased significantly.X-ray diffraction spectra indicated the formation of new species,basic copper chloride(Cu_(2)(OH)_(3)Cl),during the reaction.As the reaction progressed,these new species agglomerated,leading to a gradual loss of catalyst activity.Moreover,the deactivated catalyst was successfully reactivated using a simple alkaline washing method.展开更多
目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,...目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,统计分析专家的基本信息和问卷结果,包括专家积极系数、肯德尔和谐系数以及指标评分均数、满分比、变异系数等。结果专家的遴选体现了较高权威性,2轮德尔菲问卷回收率为76.47%和100%,专家权威系数均高于0.7,Kendall s W分别为0.271、0.308,专家意见总体协调性较好。“技术创新”指标均数<3.5且满分比7.69%予以删除;根据专家意见,增加“可操作性”“技术成熟度”三级指标,对“标准转化应用”“与相关政策规范协调”“提高效率”“能源消耗”“市场需求”等指标进行相应调整。结论初步构建了包含3个一级指标9个二级指标和27个三级指标的中医药国际标准实施效果评价指标体系,从标准技术水平、实施情况和实施效益3个维度体现了标准实施效果评价环节的全面性,为开展中医药国际标准实施效果评价研究提供了指导与参考。展开更多
命名数据网(named data networking,NDN)是一种以信息为中心的新型网络架构方案,网内缓存是其核心功能之一。现有缓存模块主要以应用级缓存实现为主,存在网络操作效率低、设备兼容性差、部署位置受限等问题。相比于应用级缓存模块,内核...命名数据网(named data networking,NDN)是一种以信息为中心的新型网络架构方案,网内缓存是其核心功能之一。现有缓存模块主要以应用级缓存实现为主,存在网络操作效率低、设备兼容性差、部署位置受限等问题。相比于应用级缓存模块,内核级缓存模块可以直接且广泛地部署于通用网络设备上,有助于推动网内缓存技术的规模应用以及NDN网络方案的实际部署。然而,由于NDN网内缓存机制涉及频繁的逐包缓存操作,将网内缓存功能引入内核将会影响内核处理性能。针对这一性能问题,设计并实现了一种内核级缓存方法。该方法维护一个哈希表进行缓存的精确查找,利用NDN名称的结构性,在节点间构建字典树支撑NDN缓存模糊匹配功能。提出使用细粒度的逐槽锁保护缓存查找表,原子操作保护替换队列,将缓存操作多线程并行化。在Linux内核中实现了所提的多线程缓存模块,实验结果表明,所提出的方法可以将缓存模块查找延迟降低至现有方案的一半,并且通过多线程将吞吐量提升至6.785 Mpacket/s。展开更多
基金supported by the National Natural Science Foundation of China(22008212,22078292,21902124)Natural Science Basic Research Planning Shaanxi Province of China(2017ZDJC-29)+2 种基金Key Research and Development Project of Shaanxi Province(2018ZDXM-GY-173)China Postdoctoral Science Foundation(2019 M663848)Open cooperative innovation fund of Xi'an Institute of modern chemistry(SYJJ48).
文摘Chlorotrifluoroethylene(CTFE)is a vital fluorinated olefinic monomer produced through the catalytic hydrodechlorination of trichlorotrifluoroethane(CFC-113),an eco-friendly process.However,hydrodechlorination catalysts for olefin production often suffer from poor stability.The Pd/AC catalyst and Pd-Cu/AC catalyst prepared by co-impregnation method exhibited poor stability,Pd-Cu/AC catalyst with CFC-113 conversion dropping to around 37%after 50 h of hydrodechlorination reaction.Brunauer-Emmett-Teller,transmission electron microscopy,X-ray photoelectron spectroscopy,and X-ray diffraction of fresh and deactivated Pd/AC catalysts indicate that the deactivation of Pd/AC catalysts is due to high-temperature agglomeration of Pd.Comparative analysis of fresh and deactivated Pd-Cu/AC catalysts using Brunauer-Emmett-Teller,transmission electron microscopy,and thermogravimetric analysis techniques revealed decreased dispersion of active sites,reduced surface area,catalyst aggregation deactivation,and a significant decrease in Cu content.Furthermore,the results of NH3-TPD revealed that the acid sites of the catalyst increased significantly.X-ray diffraction spectra indicated the formation of new species,basic copper chloride(Cu_(2)(OH)_(3)Cl),during the reaction.As the reaction progressed,these new species agglomerated,leading to a gradual loss of catalyst activity.Moreover,the deactivated catalyst was successfully reactivated using a simple alkaline washing method.
文摘目的探索性构建一个科学的中医药国际标准实施效果评价指标体系以指导标准实施效果评价工作。方法通过文献分析、专家访谈等方法建立中医药国际标准实施效果评价指标框架,并开展2轮德尔菲问卷,收集专家对各指标的重要性评分及修改意见,统计分析专家的基本信息和问卷结果,包括专家积极系数、肯德尔和谐系数以及指标评分均数、满分比、变异系数等。结果专家的遴选体现了较高权威性,2轮德尔菲问卷回收率为76.47%和100%,专家权威系数均高于0.7,Kendall s W分别为0.271、0.308,专家意见总体协调性较好。“技术创新”指标均数<3.5且满分比7.69%予以删除;根据专家意见,增加“可操作性”“技术成熟度”三级指标,对“标准转化应用”“与相关政策规范协调”“提高效率”“能源消耗”“市场需求”等指标进行相应调整。结论初步构建了包含3个一级指标9个二级指标和27个三级指标的中医药国际标准实施效果评价指标体系,从标准技术水平、实施情况和实施效益3个维度体现了标准实施效果评价环节的全面性,为开展中医药国际标准实施效果评价研究提供了指导与参考。
文摘命名数据网(named data networking,NDN)是一种以信息为中心的新型网络架构方案,网内缓存是其核心功能之一。现有缓存模块主要以应用级缓存实现为主,存在网络操作效率低、设备兼容性差、部署位置受限等问题。相比于应用级缓存模块,内核级缓存模块可以直接且广泛地部署于通用网络设备上,有助于推动网内缓存技术的规模应用以及NDN网络方案的实际部署。然而,由于NDN网内缓存机制涉及频繁的逐包缓存操作,将网内缓存功能引入内核将会影响内核处理性能。针对这一性能问题,设计并实现了一种内核级缓存方法。该方法维护一个哈希表进行缓存的精确查找,利用NDN名称的结构性,在节点间构建字典树支撑NDN缓存模糊匹配功能。提出使用细粒度的逐槽锁保护缓存查找表,原子操作保护替换队列,将缓存操作多线程并行化。在Linux内核中实现了所提的多线程缓存模块,实验结果表明,所提出的方法可以将缓存模块查找延迟降低至现有方案的一半,并且通过多线程将吞吐量提升至6.785 Mpacket/s。
