The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive positi...The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.展开更多
Interconnection networks are hardware fabrics supporting communications between individual processors in multi- computers. The low-dimensional k-ary n-cubes （or torus） with adaptive wormhole switching have attracted...Interconnection networks are hardware fabrics supporting communications between individual processors in multi- computers. The low-dimensional k-ary n-cubes （or torus） with adaptive wormhole switching have attracted significant research efforts to construct high-performance interconnection networks in contemporary multi-computers. The arrival process and destination distribution of messages have great effects on network performance. With the aim of capturing the characteristics of the realistic traffic pattern and obtaining a deep understanding of the performance behaviour of interconneetion networks, this paper presents an analytical model to investigate the message latency in adaptive-routed wormhole-switched torus networks where there exists hot-spot nodes and the message arrivals follow a batch arrival process. Each generated message has a given probability to be directed to the hot-spot node. The average degree of virtual channel multiplexing is computed by the GE/G/1/V queueing system with finite buffer capacity. We compare analytical results of message latency with those obtained through the simulation experiments in order to validate the accuracy of the derived model.展开更多
GE CT除定期更换球管外,机架稳定性极高,但扫描床较容易出故障。除Revolution系列外GE CT均配置GT1700V扫描床。本文分析总结了GT1700V扫描床的常见故障2例,以供同行交流。1故障一故障现象:扫描床运动时产生摩擦声。故障分析与排除:GE...GE CT除定期更换球管外,机架稳定性极高,但扫描床较容易出故障。除Revolution系列外GE CT均配置GT1700V扫描床。本文分析总结了GT1700V扫描床的常见故障2例,以供同行交流。1故障一故障现象:扫描床运动时产生摩擦声。故障分析与排除:GE扫描床经常会出现人为造成的外壳变形。经常被撞到的外壳部分是几片金属挡板,其材质容易变形,从而导致扫描床升降时产生摩擦声。对于轻微变形,一般将挡板扳直即可。此外,对扫描床要加强保护,比如建立护栏,更好的做法是放置台阶凳,以减少扫描床升降频率,保护信号线。如机器经常做增强,造影剂会滴落到床上,形成结晶,一级床运动时也会产生明显的摩擦声。对于此类故障,需要将一级床推到最外侧,拆下两侧板,清洗床面。展开更多
GE V730彩色超声诊断仪具有优良的图像质量及先进的应用功能,在实际的医疗诊断服务过程中具有重要的应用价值。但由于Win2000系统自身稳定性相对不足、仪器在实际诊断过程中使用频繁以及相关工作人员操作不规范等原因,使得GE V730彩色...GE V730彩色超声诊断仪具有优良的图像质量及先进的应用功能,在实际的医疗诊断服务过程中具有重要的应用价值。但由于Win2000系统自身稳定性相对不足、仪器在实际诊断过程中使用频繁以及相关工作人员操作不规范等原因,使得GE V730彩色超声诊断仪在使用过程中经常发生故障,若故障无法及时排查,则会在一定程度上降低仪器的运行效用。本文分别对彩超诊断仪的不定时自动关机故障、开机后系统无法正常启动故障以及旋钮及按键失灵故障进行了故障排查及维修分析,供相关仪器检修工作人员参考借鉴。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61574171,61704127,11875229,51872251,and 12027813)。
文摘The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.
基金supported by the UK EPSRC research grant(No. EP/C525027/1) Nuffield Foundation (No. NAL/00682/G).
文摘Interconnection networks are hardware fabrics supporting communications between individual processors in multi- computers. The low-dimensional k-ary n-cubes （or torus） with adaptive wormhole switching have attracted significant research efforts to construct high-performance interconnection networks in contemporary multi-computers. The arrival process and destination distribution of messages have great effects on network performance. With the aim of capturing the characteristics of the realistic traffic pattern and obtaining a deep understanding of the performance behaviour of interconneetion networks, this paper presents an analytical model to investigate the message latency in adaptive-routed wormhole-switched torus networks where there exists hot-spot nodes and the message arrivals follow a batch arrival process. Each generated message has a given probability to be directed to the hot-spot node. The average degree of virtual channel multiplexing is computed by the GE/G/1/V queueing system with finite buffer capacity. We compare analytical results of message latency with those obtained through the simulation experiments in order to validate the accuracy of the derived model.
