单轴压缩下含水砂岩强度损伤及声发射特征

宁东煤田主采煤层顶板广泛分布含水砂岩,该层砂岩受采动影响易于变形失稳。通过实验室试验,定量分析了含水砂岩组分,研究了其烘干、吸水随时间变化规律。研究发现该含水砂岩富含黏土矿物,砂岩分别烘干和浸水6h后含水率变化趋于稳定,且随着含水率增加该砂岩单轴抗压强度和弹性模量呈指数函数减小。声发射试验结果表明：干燥状态下,含水砂岩声发射计数峰值与应力峰值相对应,而随着含水率增加,声发射计数峰值较应力峰值位置滞后,呈现出“延迟”特征,并据此提出了预测预报该类砂岩顶板稳定的技术思路。     

锈蚀钢筋混凝土的粘结性能退化的试验研究

通过电化学原理对钢筋混凝土拔出试件进行加速锈蚀并控制其锈蚀量,根据锈蚀变形钢筋的拔出试验结果表明：由于变形钢筋与混凝土间化学胶结力、机械咬合力、混凝土对钢筋的约束力随钢筋锈蚀率的增加而明显下降,钢筋与混凝土间的粘结性能与剪切刚度性能明显退化。最后根据试验结果的统计分析,建立了钢筋锈蚀率与粘结性能的关系     

中国城市化与地质灾害之探讨

在大量调查、分析与研究的基础上，结合中国中城市近几年来快速发展中面临的一系列地质灾害，采用自然科学与社会科学相互交叉的方法，分析了城市地质灾害的危害性及对城市发展的影响，根据中国城市发展的实际情况和２０００年国民经济发展计划及２０１０年远景目标，因地制宜地提出了整治城市地质灾害的基本对策与管理措施，为国家在制定城市发展远景规划和奋斗目标提供基本思路。     

Steady-state thermal-hydraulic analysis of SCWR assembly

Among the six gen-IV reactor concepts recommended by the gen-IV international forum (GIF), supercritical water-cooled reactor (SCWR), the only reactor with water as coolant, achieves a high thermal efficiency and, subsequently, has economic advantages over the existing reactors due to its high outlet temperature. A thermal-hydraulic analysis of the SCWR assembly is performed in this paper using the modified COBRA-IV code. Two approaches to reduce the hot channel factor are investigated: decreasing the moderator mass flow and increasing the thermal resistance between moderator channel and its adjacent sub-channels. It is shown that heat transfer deterioration cannot be avoided in SCWR fuel assembly. It is, therefore, highly required to calculate the cladding temperature accurately and to preserve the fuel rod cladding integrity under heat transfer deterioration conditions. __________ Translated from Nuclear Power Engineering, 2007, 28(5): 18–21, 58 [译自: 核动力工程]     

Reactivity deterioration of NiO/Al2O3 oxygen carrier for chemical looping combustion of coal in a 10 kWth reactor

A relatively long-term experiment for chemical looping combustion of coal with NiO/Al₂O₃ oxygen carrier was carried out in a 10 kW_th continuous reactor of interconnected fluidized beds, and 100 h of operation was reached with the same batch of the oxygen carrier. The reactivity deterioration of the oxygen carriers was present during the experimental period. The reactivity deterioration of reacted oxygen carriers at different experimental stages was evaluated using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray fluorescence spectrometer. SEM analysis showed no significant change in the morphology of the nickel-based oxygen carrier at the fuel reactor temperature ?940 °C, but loss of surface area and porosity of reacted oxygen carriers was observed when the fuel reactor temperature exceeded 960 °C. The results show that the sintering effect have mainly contributed to the reactivity deterioration of reacted oxygen carriers in the CLC process for coal, while the effects of coal ash and sulfur can be ignored. The oxidization of reduced oxygen carrier with air was an intensive exothermic process, and the high temperature of oxygen carrier particles led to sintering on the surface of oxygen carrier particles in the air reactor. Attention must be paid to control the external circulation of oxygen carrier particles in the interconnected fluidized beds in order to efficiently transport heat from the air reactor to the fuel reactor, and reduce the temperature of oxygen carrier particles in the air reactor. Improvement of reactivity deterioration of reacted oxygen carriers was achieved by the supplement of steam into the fuel reactor. Nevertheless, NiO/Al₂O₃ is still one of the optimal oxygen carriers for chemical looping combustion of coal if the sintering of oxygen carrier is minimized at the suitable reactor temperature.     

食品品质损失动力学模型

主要讨论了Ａｒｒｈｅｎｉｕｓ模型和Ｚ值模型的各自特点及相互关系，提出了两种模型中活化能Ｅａ和Ｚ值两者 实用关系式，搪塞了描述食品品质损失规律的其它方法。     

功率发光二极管的寿命预测

针对功率发光二极管(LED)的使用寿命问题,提出了利用阿仑尼斯模型预测功率发光二极管器件寿命的方法,以器件输出光功率P下降到初始值P0的50%为失效判据,通过对功率蓝光GaN LED芯片两个结温点的高温恒定应力加速寿命实验结果进行分析计算,求出了功率蓝光GaN LED器件在正常应力条件下的期望寿命,确定阿仑尼斯模型在功率发光二极管寿命实验过程中的适用性,为预测功率发光二极管寿命提供理论依据.     

干湿循环与盐湖卤水侵蚀共同作用下喷射混凝土的劣化及其机理

通过对比普通混凝土、普通喷射混凝土和钢纤维喷射混凝土在(干湿循环+盐湖卤水侵蚀)共同作用下的外观形貌、抗压强度、物相组成和微观结构,研究了喷射混凝土的劣化及其机理.结果表明:(干湿循环+盐湖卤水侵蚀)150次时,普通混凝土外观形貌破损严重,喷射混凝土外观形貌较完整;普通混凝土抗压强度＜普通喷射混凝土＜钢纤维喷射混凝土;钢纤维喷射混凝土表层微观结构较为致密且存在CH,侵蚀产物石膏在侵蚀后期发生了二次反应;其劣化侵蚀机理包括NaCl、MgCl2、Na2SO4和MgSO4的物理结晶侵蚀及碳酸盐、硫酸盐和镁盐的化学侵蚀,但未发现氯盐的化学侵蚀产物,而喷射混凝土中还发生碳硫硅钙石型硫酸盐侵蚀.     

旋转机械运行稳定性劣化的高阶累积量特征提取方法

研究了基于高阶累积量理论的1.5维谱、四阶累积量对角切片谱方法在提取运行稳定性劣化特征方面的性能;从敏感性、趋势性、差异性、一致性角度,讨论了两种特征提取方法的趋势预测适用性。基于构建的转子实验台进行转子系统多种劣化类型下不同劣化程度状态的特征提取实验,检验两种方法作为特征提取手段的性能,解决了风电机组传动系统运行稳定性劣化的状态诊断、劣化趋势预测中特征提取方法的选择缺少理论依据的问题。     

通信电源防雷器自脱扣原理的研究

LPTP能保护通信电源设备免受过电压及雷击的损害,但当LPTP失效后会发热,对设备造成起火的威胁,因此LPTP失效后必需从电路中断开。合理地选择LPTP劣化后的自动脱扣点很重要。通过对一种LPTP自动脱扣点参数的研究和测量,说明LPTP自动脱扣点的选择方法。