针对华中科技大学自由电子激光(free electron laser,FEL)太赫兹源直线加速器束流调节环节存在的开环控制、运行卡顿、数据传输困难、处理滞后等问题,分析了微波功率源谐振频率与加速管腔体温度对束流能散度的影响,以此为理论基础设计...针对华中科技大学自由电子激光(free electron laser,FEL)太赫兹源直线加速器束流调节环节存在的开环控制、运行卡顿、数据传输困难、处理滞后等问题,分析了微波功率源谐振频率与加速管腔体温度对束流能散度的影响,以此为理论基础设计了束流能散度自动调节系统。该系统以Labview程序为软件开发平台,包括用户层、数据交互层与物理层3层结构,采用分布式控制方案,分为调束与运行监控2个子系统,子系统间通过实验物理与工业控制系统通讯。该系统界面友好、操作流畅、响应迅速、功能稳定,在高重复频率下使能散度快速达到最佳状态。展开更多
Thermal cracking occurs in the plastic packaging materials due to the presence of moisturized micro-cavities in the material.The moisture resident in the micro-cavities gives rise to the internal vapor pressure that d...Thermal cracking occurs in the plastic packaging materials due to the presence of moisturized micro-cavities in the material.The moisture resident in the micro-cavities gives rise to the internal vapor pressure that drives the thermal expansion of micro-cavities as temperature rises.The plastic packaging materials are considered a class of thermo-hyperelastic materials,thus allowing the micro-cavities to thermally expand to the substantial extent before the cracking failure.The micro-cavities can be moisture-abundant(i.e.,wet) or substantially dry when cracking occurs.Cracking appears to be almost certain in the presence of wet cavities.The possibility of cracking in dry cavities turns to be two-sided:when the initial volume fraction of the micro-cavities is relatively small,cracking cannot occur in the dry cavities regardless of the phase transition temperature;when the initial cavity volume fraction is relatively large,cracking tends to occur in the dry cavities especially when the phase transition temperature is large.Because of the two-sided cracking possibility,the dry-cavity cracking mode presents a scenario that might reveal the mechanism of popcorning-type cracking failure in plastic packaging materials.展开更多
文摘针对华中科技大学自由电子激光(free electron laser,FEL)太赫兹源直线加速器束流调节环节存在的开环控制、运行卡顿、数据传输困难、处理滞后等问题,分析了微波功率源谐振频率与加速管腔体温度对束流能散度的影响,以此为理论基础设计了束流能散度自动调节系统。该系统以Labview程序为软件开发平台,包括用户层、数据交互层与物理层3层结构,采用分布式控制方案,分为调束与运行监控2个子系统,子系统间通过实验物理与工业控制系统通讯。该系统界面友好、操作流畅、响应迅速、功能稳定,在高重复频率下使能散度快速达到最佳状态。
基金supported by the National Natural Science Foundation of China (Grant No. 11172195)the Natural Science Foundation of Shanxi Province,China (Grant No. 2012011019-4)
文摘Thermal cracking occurs in the plastic packaging materials due to the presence of moisturized micro-cavities in the material.The moisture resident in the micro-cavities gives rise to the internal vapor pressure that drives the thermal expansion of micro-cavities as temperature rises.The plastic packaging materials are considered a class of thermo-hyperelastic materials,thus allowing the micro-cavities to thermally expand to the substantial extent before the cracking failure.The micro-cavities can be moisture-abundant(i.e.,wet) or substantially dry when cracking occurs.Cracking appears to be almost certain in the presence of wet cavities.The possibility of cracking in dry cavities turns to be two-sided:when the initial volume fraction of the micro-cavities is relatively small,cracking cannot occur in the dry cavities regardless of the phase transition temperature;when the initial cavity volume fraction is relatively large,cracking tends to occur in the dry cavities especially when the phase transition temperature is large.Because of the two-sided cracking possibility,the dry-cavity cracking mode presents a scenario that might reveal the mechanism of popcorning-type cracking failure in plastic packaging materials.
