化石燃料的枯竭和不断增长的能源需求给人类带来巨大的挑战,加之能源消耗过程带来的环境问题使得开发清洁可再生绿色能源迫在眉睫.氢能具有零排放、可再生、能量高和来源广等特点,且可通过化石能源和电解水制取,是未来人类最理想的替代...化石燃料的枯竭和不断增长的能源需求给人类带来巨大的挑战,加之能源消耗过程带来的环境问题使得开发清洁可再生绿色能源迫在眉睫.氢能具有零排放、可再生、能量高和来源广等特点,且可通过化石能源和电解水制取,是未来人类最理想的替代能源之一.相较于化石能源制氢,电解水制氢被认为是一种最有前途的清洁制氢技术,能够将可再生能源(例如太阳能和风能)产生的剩余电能以化学能的形式存储起来.电解水反应由发生在阴极的析氢反应与发生在阳极的析氧反应组成.其中,析氧反应涉及多个质子和电子转移,反应动力学缓慢严重限制了其水分解的整体效率.为满足实际应用,亟待开发低成本、高催化活性和在工业电解条件(60-80℃,20%-30%KOH,400mA·cm^(-2))下长期稳定性强等特性的析氧催化剂.本文报道了一种用于析氧反应的自支撑泡沫镰铁自支撑的镰铁层状双金属氢氧化物-二硫化钼(NiFe LDH-MoS_(x)/INF)集成电极,在正常碱性测试条件(25℃,1 M KOH)和模拟工业电解条件(65℃,5 M KOH)下均表现出优异的催化性能.优化后的电极在一般碱性测试条件下,过电势仅需195和290 mV即可达到100和400mA·cm^(-2)的电流密度.在模拟工业电解条件下达到相同的电流密度,过电势只需156和201mV.在两种条件下进行长期稳定性测试,催化剂均未观察到明显的失活现象.在两电极体系(NiFe LDH-MoS.yiNF||20%Pt/C)全解水测试中,达到100mA·cm^(-2)电流密度仅需1.72 V的电压.还使用NiFe LDH-MoS.v/INF作为阳极催化剂构建膜电极并评价其阴离子交换膜电解水的性能:在400mA·cm^(-2)的电流密度下能量转换效率(60℃,1 M KOH)为71.8%.综上,原位生长策略保证了此类电极的长期稳定性.硫化基底的存在可以控制NiFe LDH的生长厚度,从而提高集成电极的整体导电性.另外,MoS_(x)的引入进一步调节了NiFe LDH的电子结构,进而优化了反应中间体的吸附能及状态.在模拟工业操作条件下进行的电化学测试进一步证实了多孔三维自支撑NiFe LDH-MoS_(x)/INF集成电极具有在工业电解水中大规模应用的前景.本文为合理设计用于工业阴离子交换膜水电解的非贵金属析氧催化剂提供新的策略.展开更多
Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the public...Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the publically available Freight Analysis Framework (FAF2.2) database and U.S. highway and networks and TransCAD, a geographic information system with strong transportation modeling capabilities. The binary logit model and the regression model both use the same set of generic variables, including mode split probability, commodity weight, value, network travel time, and fuel cost. The results show that both the binary logit and regression models perform well for cereal grains transportation in the United States, with the binary logit model yielding overall better estimates with respect to the observed truck and rail mode splits. The two models can be used to study other commodities between two modes and may produce better results if more mode specific variables are used.展开更多
Background The control system of China ADS front-end demo linac(CAFe)is a distributed control system based on experimental physics and industrial control system(EPICS).The data generated by the control system are stor...Background The control system of China ADS front-end demo linac(CAFe)is a distributed control system based on experimental physics and industrial control system(EPICS).The data generated by the control system are stored and retrieved by Channel Archiver.However,with the development of accelerator devices,its scale continues to expand.Channel Archiver has been unable to meet the increasing data volume in terms of availability,performance,and storage expansion.Purpose This paper presents a new data archiving system of EPICS control system.The archive engine is developed with microservice architecture,and the data storage layer uses the distributed database—HBase.Method The archive engine supports a variety of archive modes,and process variable(PV)archive requests and confguration changes can be realized without restarting.It can also realize data retrieval in a variety of ways.In addition,python scripts and Web UI can be used to implement the management functions of the system.Results Currently,the archiving system is under commissioning at CAFe facility.The results show that the new archiving system is convenient to operate and easy to expand and provides a research platform for future data analysis.展开更多
文摘化石燃料的枯竭和不断增长的能源需求给人类带来巨大的挑战,加之能源消耗过程带来的环境问题使得开发清洁可再生绿色能源迫在眉睫.氢能具有零排放、可再生、能量高和来源广等特点,且可通过化石能源和电解水制取,是未来人类最理想的替代能源之一.相较于化石能源制氢,电解水制氢被认为是一种最有前途的清洁制氢技术,能够将可再生能源(例如太阳能和风能)产生的剩余电能以化学能的形式存储起来.电解水反应由发生在阴极的析氢反应与发生在阳极的析氧反应组成.其中,析氧反应涉及多个质子和电子转移,反应动力学缓慢严重限制了其水分解的整体效率.为满足实际应用,亟待开发低成本、高催化活性和在工业电解条件(60-80℃,20%-30%KOH,400mA·cm^(-2))下长期稳定性强等特性的析氧催化剂.本文报道了一种用于析氧反应的自支撑泡沫镰铁自支撑的镰铁层状双金属氢氧化物-二硫化钼(NiFe LDH-MoS_(x)/INF)集成电极,在正常碱性测试条件(25℃,1 M KOH)和模拟工业电解条件(65℃,5 M KOH)下均表现出优异的催化性能.优化后的电极在一般碱性测试条件下,过电势仅需195和290 mV即可达到100和400mA·cm^(-2)的电流密度.在模拟工业电解条件下达到相同的电流密度,过电势只需156和201mV.在两种条件下进行长期稳定性测试,催化剂均未观察到明显的失活现象.在两电极体系(NiFe LDH-MoS.yiNF||20%Pt/C)全解水测试中,达到100mA·cm^(-2)电流密度仅需1.72 V的电压.还使用NiFe LDH-MoS.v/INF作为阳极催化剂构建膜电极并评价其阴离子交换膜电解水的性能:在400mA·cm^(-2)的电流密度下能量转换效率(60℃,1 M KOH)为71.8%.综上,原位生长策略保证了此类电极的长期稳定性.硫化基底的存在可以控制NiFe LDH的生长厚度,从而提高集成电极的整体导电性.另外,MoS_(x)的引入进一步调节了NiFe LDH的电子结构,进而优化了反应中间体的吸附能及状态.在模拟工业操作条件下进行的电化学测试进一步证实了多孔三维自支撑NiFe LDH-MoS_(x)/INF集成电极具有在工业电解水中大规模应用的前景.本文为合理设计用于工业阴离子交换膜水电解的非贵金属析氧催化剂提供新的策略.
文摘Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the publically available Freight Analysis Framework (FAF2.2) database and U.S. highway and networks and TransCAD, a geographic information system with strong transportation modeling capabilities. The binary logit model and the regression model both use the same set of generic variables, including mode split probability, commodity weight, value, network travel time, and fuel cost. The results show that both the binary logit and regression models perform well for cereal grains transportation in the United States, with the binary logit model yielding overall better estimates with respect to the observed truck and rail mode splits. The two models can be used to study other commodities between two modes and may produce better results if more mode specific variables are used.
文摘Background The control system of China ADS front-end demo linac(CAFe)is a distributed control system based on experimental physics and industrial control system(EPICS).The data generated by the control system are stored and retrieved by Channel Archiver.However,with the development of accelerator devices,its scale continues to expand.Channel Archiver has been unable to meet the increasing data volume in terms of availability,performance,and storage expansion.Purpose This paper presents a new data archiving system of EPICS control system.The archive engine is developed with microservice architecture,and the data storage layer uses the distributed database—HBase.Method The archive engine supports a variety of archive modes,and process variable(PV)archive requests and confguration changes can be realized without restarting.It can also realize data retrieval in a variety of ways.In addition,python scripts and Web UI can be used to implement the management functions of the system.Results Currently,the archiving system is under commissioning at CAFe facility.The results show that the new archiving system is convenient to operate and easy to expand and provides a research platform for future data analysis.
