特高压气体绝缘开关设备中特快速瞬态过电压特性的试验研究

气体绝缘开关设备（gas insulated switchgear,GIS）中隔离开关操作产生的特快速瞬态过电压（very fast transientovervoltage,VFTO）会影响电气设备的安全运行,随着系统电压等级的提高,该影响会越来越严重,在特高压系统中尤为突出。为掌握特高压GIS的VFTO特性,在特高压GIS设备的VFTO试验回路进行了大规模GIS隔离开关操作试验,并对VFTO测量结果进行了统计分析。研究得到了VFTO全过程波形的波形特征、击穿次数、频率成份和残余电压分布,单次击穿波形的波形特征和振荡系数分布,及预充/不预充直流电压下的VFTO幅值特性,揭示了隔离开关加装阻尼电阻对VFTO的抑制作用。所获得的特高压GIS中的VFTO特性为进一步研究VFTO仿真和绝缘配合等提供了依据。     

特高压气体绝缘开关设备中特快速瞬态过电压测量用电容传感器的标定

为保证特高压气体绝缘开关设备（gas insulatedswitchgear,GIS）中特快速瞬态过电压（very fast transientovervoltage,VFTO）测量用手孔式电容传感器的准确性,必须对其进行标定。研制了用于电容传感器的标定系统,它由3种不同幅值及波形的脉冲源及相应测量系统组成。其中：低电压陡脉冲源用于校验电容传感器的高频特性;高电压陡脉冲源用于校验传感器在高压下的稳定性;低电压长波尾电源用于校验传感器的低频特性。水电阻分压器及金属膜电阻分压器用于测量3种脉冲源的输出波形,在标定电容分压器前,对电阻分压器的频率特性及线性度特性进行了试验。电容传感器的标定试验结果表明,华北电力大学和清华大学研制的电容传感器均具有良好的频率特性、线性度和稳定性,可以满足特高压GIS设备VFTO测量工作的需要。     

已发布及可预见的高度关注物质对纺织化学品的影响（一）

介绍了REACH法规附件XVI和XVII中有关高度关注物质的修订情况,并从致癌芳胺及涉嫌禁用偶氮染料、三芳甲烷染料和致癌染料、无机颜料、有机溶剂、印染助剂（包括邻苯二甲酸酯类增塑剂、阻燃剂、防水拒油剂、有机锡等）、助剂原料、有害重金属对今后可能涉及的高度关注物质作了预测,并详细解读了它们的应用领域和危害性。     

Oracle超大型数据库逻辑迁移实践

针对通信行业实践中现有超大型数据库迁移存在方案复杂和难度大等问题,给出基于Export/Import和数据泵技术的数据逻辑迁移解决方案。首先,对Oracle数据库逻辑迁移解决方案的逻辑迁移技术和迁移过程进行分析,指出迁移过程需要考虑的多种因素。然后,对方案进行具体应用。实践表明该方案具有有效性。     

RESRAD程序在极低放废物填埋场辐射影响评价中的应用研究

运用RESRAD程序对开放利用国内某极低放废物填埋场的辐射影响进行了评价。简述了RESRAD程序的基本原理、子模型和计算方法,分析了RESRAD程序场址特定参数的选取和处理。选定"农业居民用"情景,计算了填埋场关闭后进行开放利用对居住者的辐射剂量,并进一步分析了关键照射途径和关键核素。结果表明,开放利用这一特定填埋场,居住者最大年有效剂量为0.003mSv,是全球公众天然本底辐射剂量平均值的0.13%。短寿命放射性核素对剂量贡献很小;阻滞系数小的中长寿命放射性核素对剂量贡献大,且主要通过地下水途径对居住者进行照射;加强室内通风是减小氡辐射剂量的有效方式。     

螺杆马达在极倾斜地层中的应用

针对云南宣威华泽项目施工钻孔地层倾角极陡的情况,经过反复试验,探索出针对该地层的孔口定向+螺杆马达定向钻具的施工方法,及时完成了钻探施工,取得了很好的经济效果。介绍了螺杆马达在该矿区的应用及取得的效果。     

Numerical simulation of the coupling between thermal dissipation and fish‐eye crack growth in very high cycle fatigue regime

In this paper, we study the temperature field associated with the propagation of a fatigue crack in a very high cycle fatigue regime during ultrasonic fatigue testing. We use a Paris–Hertzberg crack growth law to compute the evolution of the crack and a perfectly elastic–plastic constitutive law to compute the plastic dissipation per cycle at the tip of the crack. A thermomechanical finite element model is proposed to estimate the evolution of the temperature field during the crack propagation. Numerical results obtained agree fairly well with experimental results.     

Ductility Loss of Zircaloy Cladding by Inner-Surface Oxidation during High Temperature Transient

Under a LOCA transient in LWRs, ruptured Zircaloy clad tubes would be oxidized at the inner surface as well as outer surface by steam flowing in reactor core. In order to determine whether the inner-surface oxidation influences mechanical properties of clad tubes during the reflood stage of a LOCA, the ring compression tests were conducted on oxidized tube specimens and segments sectioned from ruptured claddings obtained from rod-burst/oxidation tests ranging from 1,200 to 1,500 K.

The degradation of the fracture load and the deflection at 373 K are largely influenced by the hydrogen absorption during the inner-surface oxidation. The oxidation temperature and the time dependence of the ductility loss of Zircaloy clad tubes can be represented by iso-deflection lines. The iso-deflection lines due to the hydrogen absorption limit the permissible oxidation condition to a lower temperature and shorter period of exposure time, comparing with sole oxygen uptake.     

Vaporization Study on Vanadium-Oxygen Solid Solution by Mass Spectrometric Method

The vapor pressures over vanadium-oxygen solid solution (0.001≦O/V≦0.145) were measured by mass-spectrometric method in the temperature range of 1,855–2,117K. The main vapor species were observed to be V(g) and VO(g). The vapor pressure of V(g) is higher than that of VO(g) over the solid solutions with all O/V ratios except for O/V=0.145. The vapor pressure of V(g) is nearly independent of O/V ratio. The vapor pressure of VO(g) decreases with decreasing O/V ratio. The oxygen partial pressure was calculated as a function of temperature and O/V ratio from the vapor pressures of V(g) and VO(g), from which the partial molar enthalpy and entropy of oxygen in the solid solution were determined. The partial molar enthalpy of oxygen was observed to be independent of composition, suggesting the presence of very weak interaction between interstitial oxygens. The compositional dependence of the partial molar entropy of oxygen can be explained by assuming the occupation of the octahedral site in bcc vanadium lattice by the interstitial oxygens. The excess partial molar entropy of oxygen was compared with the value derived from the sum of the contributions from the volume expansion, electronic heat capacity and vibrational terms.