砂岩混凝土复合路面力学分析及结构优化设计研究

针对砂岩混凝土斜向预应力混凝土基层复合路面结构层厚度,通过梁单元建立预应力钢筋模型,通过接触单元模拟了各层之间的相互作用,对砂岩混凝土复合路面进行了三维有限元建模。分析了各层厚度对于路面结构力学响应的影响,并结合经济性与极限寿命分析,对结构层厚度进行了优化分析,得出了一定范围内的最佳层厚组合,为类似工程的设计施工提供参考依据。     

预应力混凝土桥梁腐蚀后的受力性能分析

结合某铁路大桥预应力钢丝锈断后梁体的受力性能分析,对预应力混凝土桥梁腐蚀后的耐久性评估方法进行了探讨。首先,用静载试验加载方法对腐蚀梁体进行了实桥试验,分别对每孔2片T型梁的跨中挠度、支座压缩量、跨中及L/4截面混凝土应力、内梁预应力钢丝锈断截面处的混凝土应力进行了测试;然后,对受腐蚀预应力混凝土桥梁进行了有限元分析。介绍了正常梁体和腐蚀梁体的有限元模型、有限元网格剖分建立。在预应力梁体的耐久性分析中,应重点考虑预应力筋锈蚀的影响,并给出了预应力筋的简化分析模型。通过对梁体有限元计算结果和试验值的比较,验证了计算模型基本上能准确地反映梁体的受力情况,说明可以采用有限元方法对预应力混凝土桥梁腐蚀后的耐久性进行评估。     

CFRP用于火灾后钢筋混凝土梁抗弯加固的试验研究及有限元分析

笔者结合对结构火灾损伤的分析 ,采用有限元分析软件ANSYS对火灾后CFRP加固钢筋混凝土梁荷载与应变、挠度的关系进行了数值分析 ,并与试验结果进行了比较 ,吻合良好。加固后的混凝土梁在钢筋屈服后 ,仍然有一定的荷载容量。这种荷载承受能力可一直持续到结构破坏 ,这主要是碳纤维布在后期发挥的作用 ,用碳纤维布加固受火后的混凝土梁 ,能明显地提高梁的极限承载力 ,在钢筋屈服后对梁的刚度有较大幅度的提高。在挠度的计算中 ,在钢筋屈服后 ,有限元模型由于混凝土的裂缝快速发展 ,刚度下降很大 ,所以挠度在相同荷载下 ,稍大于试验值。这与笔者提出的扰度简化计算公式的计算结果与试验数据十分吻合。用ANSYS对CFRP加固梁进行分析能够达到比较精确的理论分析结果。     

火灾后圆钢管约束钢筋再生混凝土轴压短柱 力学性能分析

利用ABAQUS软件建立了火灾后圆钢管约束钢筋再生混凝土轴压短柱的非线性有限元模型,在确定混凝土和钢材的本构基础上,对其火灾后剩余承载力和轴压刚度进行了数值计算,并与已有相关试验数据进行比对分析。分析了升温时间、截面直径、材料强度、骨料取代率、含钢率和配筋率等参数对火灾后剩余承载力和轴压刚度的影响规律。结果表明:升温时间和截面直径是影响火灾后试件剩余承载力和轴压刚度的主要因素;提出了该类试件火灾后剩余承载力和轴压刚度的简化计算公式,可为工程实际应用提供参考。     

一种基于动生涡流磁场的钢质管道管体损伤外检测方法

钢质管道缺陷严重影响钢质管道的安全运行，目前大多数钢质管道检测方法效率较低，为提升钢质管道管体缺陷检测效率，提出一种基于动生涡流的管道缺陷高速磁检测方法，并对动生涡流磁场的检测原理进行解释。利用有限元，建立高速磁检测模型，分析动生涡流在管体的分布特点，及其与原磁场的相互作用；分析不同检测位置的磁场分布情况，选取最佳的检测位置。选用适合高速检测的多匝线圈传感器，以提高灵敏度和信号幅值。设计缺陷高速磁检测试验平台，开展不同速度、不同提离高度和不同种类缺陷(盲孔与刻槽)下的检测试验。结果显示：相较于其他检测位置，磁铁后方的动生涡流磁场强度较高，动生涡流磁场分布也较均匀，对缺陷的检测效果最佳，因此选取磁铁后方为检测点；在25 m/s的高速下，该检测方法对设置的几种缺陷仍有良好的检测效果；缺陷信号峰峰值与缺陷宽度、缺陷深度及检测速度均大致成正比；缺陷信号峰峰值与提离高度成指数关系，提离高度越大，峰值越小；缺陷信号峰峰值间距与提离高度大致成正比。综合研究显示，动生涡流磁场的检测方法与其他传统方法相比，在检测速度上有较大优势。     

高强与高性能混凝土温湿度场应力分析

针对高强与高性能混凝土易于开裂的特点,对高强高性能混凝土早期温湿度场随龄期发展的分布情况以及混凝土的收缩变形进行理论分析,建立相应的计算模型,编制三维有限元程序,分析在外界温湿度变化以及不同养护条件下由混凝土内部温差和湿度变化产生的温度应力和干燥收缩应力,从施工养护方法上探讨了高强与高性能混凝土抗裂性能的改善措施.     

扣件式钢管模板支架稳定承载力修正系数研究

通过分析6种单榀试验模型得出扣件式钢管模板支架的稳定承载力修正系数.利用有限元软件ANSYS对单榀试验模型进行模拟,分别得到扣件式钢管模板支架节点为完全刚性和半刚性的稳定承载力,进而得到由有限元计算所得稳定承载力修正系数.试验所得的稳定承载力修正系数和有限元计算所得的修正系数具有较好的一致性.因此,采用稳定承载力修正系数,能够较方便地得出扣件式钢管模板支架节点为完全刚性和半刚性的稳定承载力之间的关系.     

C50混凝土环氧涂层钢筋粘结滑移性能与强度计算研究

对环氧涂层钢筋C50混凝土试件进行轴心拉拔试验,分析钢筋直径（12 mm、14 mm）以及粘结长度（5d、8d、12d）对试件粘结性能的影响。试验结果表明：环氧涂层钢筋C50混凝土试件有钢筋拔出破坏和混凝土劈裂破坏2种破坏形式;试件粘结-滑移曲线的发展趋势受试件钢筋直径与钢筋粘结长度的影响;增大钢筋直径可以提高21.4%～86.1%的粘结力,但会使极限粘结应力先增大后减小;增大钢筋粘结长度可以提高115.0%～147.5%的粘结力,但会明显降低粘结长度较大试件的粘结强度。最后,根据试验结果提出适用于环氧涂层钢筋C50混凝土的极限粘结强度计算公式,为其工程应用提供一定参考。     

网格划分及开口处计算区域延展对FDS模拟结果的影响

结合具体算例,引入相关性分析方法对FDS应用中出现的网格独立性问题进行了量化研究,就火源区、羽流区和烟气层区对网格密度敏感性的差别进行了讨论,并且分析了开口处计算区域设置对计算结果的影响.随着网格密度的增大.不同计算结果之间的相关性值不断增大至0.99以上,且火源区的相关性值受网格密度影响最大,浮力羽流区次之,烟气层区最小.不延展计算区域和延展计算区域情况下的计算结果的相关性值较低,而不同计算区域延展范围下的计算结果之间的相关性均较高.结果表明,相关性值可以用来衡量计算结果的网格独立性.火源区、浮力羽流区、烟气层区对于网格密度的敏感程度依次递减,加密火源区在控制计算时间的同时可以有效提高计算精度.计算区域设置对于建筑开口处的烟气溢流和补气情况将产生重要影响.进而将影响到建筑内部的热流场,将开口处的计算区域适当向外延展,是保证计算结果精确度的有效手段.     

对接焊缝缺陷漏磁场特征分析及识别研究

为实现钢板对接焊缝存在不同类型缺陷的识别研究,针对铁磁性焊缝的特点,探讨应用漏磁法检测钢板对接焊缝不同类型缺陷。根据漏磁检测(MFL)原理,采用有限元方法(FEM),分别建立钢板对接焊缝中可能存在的裂纹、气孔、未熔合和未焊透等缺陷的三维FEM模型。研究钢板对接焊缝包含以上不同类型缺陷时所产生的漏磁场分布特征,得到漏磁场磁感应强度水平分量和垂直分量相关对比分析曲线。仿真结果表明:漏磁法适用于钢板对接焊缝缺陷的识别研究;根据漏磁场磁感应强度分量的曲线特征,能够实现对焊缝缺陷的分类。     

电力应急资源优化调配技术及其在电力企业的应用*

为帮助电力企业实现快速有效的应急响应及应急资源的合理利用，解决应急资源“盲调”问题，对应急资源需求预测业务、应急资源调配业务进行深入分析；基于案例推理技术、模糊评价技术，依托网络地理信息系统，优化电力应急资源调配程序，研发电力应急资源调配系统并将其应用于电力企业。结果表明:该系统可在电力企业开展突发事件应急处置时提出科学、合理的应急资源调配方案并跟踪执行，为进一步提升电力企业应急处置效率、完善电力企业应急体系提供技术支撑。     

Whether power holders construe their power as responsibility or opportunity influences their tendency to take advice from others

Empirical evidence suggests that power elicits a generic tendency to disregard advice. We examined different responses power holders may show in their tendency to take advice depending on the construal of power. We report a field study and an experiment among managers and other powerful professionals (Studies 1 and 2) and an experiment in which participants were assigned to a powerful role (Study 3). Across studies, we found a higher tendency to take advice among those who construed their power as a responsibility rather than as an opportunity. This effect of the construal of power on advice taking was mediated by a heightened perceived value of advice, not by decreased confidence in own judgments or sense of power. Accordingly, the increase in advice taking when power was construed as a responsibility was observed regardless of whether the advice came from subordinates (Study 1), expert advisors (Study 2), or a less powerful teammate (Study 3). This highlights the relevance of considering how power holders construe their power in order to understand their tendency to take advice from others. Copyright © 2017 John Wiley & Sons, Ltd.     

Predicting work performance in nuclear power plants

Diagnosis and monitoring are the major tasks of an operator in main control room of nuclear power plants (NPPs). The operator’s mental workload influences his/her performance, and furthermore, affects the system safety and operations. This study investigated the operator’s mental workload and work performance of the NPP in Taiwan. An experiment including primary and secondary tasks was designed to simulate the reactor shutdown procedure of the fourth nuclear power plant (FNPP). The performance of the secondary tasks (error rate), subjective mental workload (NASA Task Load Index, NASA-TLX) as well as seven physiological indices were assessed and measured. The group method of data handling (GMDH) was applied to integrate these physiological indices to develop a work performance predictive model. The validity of the proposed model is very well with R² = 0.84 and its prediction capability is high (95% confidence interval). The proposed model is expected to provide control room operators a reference value of their work performance by giving physiological indices. Besides NPPs, the proposed model can be applied to many other fields, e.g. aviation, air transportation control, driving and radar vigilance, etc.     

电能有功功率测量的一种简便方法

介绍了SCE7755芯片的原理、结构,重点分析了利用SCE7755芯片实现三相有功功率测量的简单方法,给出了系统的工作原理、软硬件设计.     

Assessing safety culture in nuclear power stations

Definitions of safety culture abound, but they variously refer to the safety-related values, attitudes, beliefs, risk perceptions and behaviours of all employees. This assembly may seem too inclusive to be meaningful, but each represents a different level of processing and the choice for measurement (or intervention) is more pragmatic than theoretical. The present study addresses mainly attitudes, but also reported behaviours. This is done using a 120-item questionnaire covering eight domains of safety in three nuclear power stations. Principal components analysis yields 28 factors — all but four of which are correlated with one or more of nine criteria of accident history. Differences by gender, age, shifts/days and work areas are revealed, but these are confounded by type of job and ANOVAS are applied to clarify the main sources of variation. The effects on safety culture of a number of organisational components are also explored. For example, the role of safety in team briefings, management style, work pressure versus safety, etc. It is concluded that personnel safety surveys can usefully be applied to deliver a multi-perspective, comprehensive and economical assessment of the current state of a safety culture and also to explore the dynamic inter-relationships of its ‘working parts’.     

Safety culture and the issue of power

Issues of power and conflict in organizations are rarely addressed in safety culture research. Much safety culture research thus rests upon a harmony model of organizational life. This, it is argued, is a fundamental shortcoming of the existing research. The article discusses the relationship between power-oriented and cultural approaches to organizational safety. The accident with space shuttle Challenger is used as a case, since this accident has been analysed through both approaches.The article argues that issues of culture and power are so intertwined that safety culture research should incorporate perspectives of power and conflict. This is necessary in order to be able to give a realistic account of the dynamics of organizational life. Introducing a more power-oriented view on safety culture can also serve as the basis for important ethical considerations regarding the improvement of safety culture.Finally, it is argued that a safe culture is not necessarily one which is homogenous and free from conflict. Having conflicting views on safety can in fact be a safety resource by serving as a kind of requisite variety that facilitates learning.     

电力突发事件应急管理中的博弈

电力安全一直是人们关注的问题,电力系统对无法预料的灾难性突发事件表现的非常脆弱,电力突发事件的应急管理对维护电力系统安全运行具有十分重要的意义。电力突发事件的状态是在不断变化的,应急管理人员必须根据电力突发事件发展趋势动态地调整管理活动。本文分析了突发事件应急管理中＂电力突发事件＂与＂应急管理者＂之间的动态博弈过程,＂应急管理者＂会随着＂电力突发事件＂的动态演变,不断调整其管理方法,控制住＂电力突发事件＂。通过分析＂电力突发事件＂与＂应急管理者＂之间的博弈,构建了电力突发事件有效应急管理程序。＂应急管理人员＂以动态博弈的思想处理＂电力突发事件＂,结果表明该方法能更好的发挥应急处理预案的作用,更有效的处置＂电力突发事件＂。     

Relative power and influence strategy: the effects of agent/target organizational power on superiors' choices of influence strategies

The present study examined superiors' tendency to utilize different top–down influence strategies according to their evaluation of their own power relative to that of their subordinates. Four hundred and fifty‐five subordinates (schoolteachers) from different schools described the extent to which their superiors used each item of the influence strategy questionnaire to influence them, while their immediate superiors evaluated superior's power and subordinate's power. Overall, superiors tended to use soft and rational strategy more often than hard strategy. However, regarding the parameter of relative power, the results indicated that the agent's power, as well as the target's power, affected the superior's choice of particular influence strategy. The results suggest that power should be discussed in relative rather than absolute terms. Copyright © 2001 John Wiley & Sons, Ltd.     

核电厂HRA组织定向研究

概率安全评价(PSA)已经成为核电厂定量化安全评价的主要方法,人因可靠性分析(HRA)是其中重要组成部分.传统的HRA方法研究对象主要是"个体失误",而HRA的全面评估必须考虑"组织情景",HRA必须组织定向.分析了HRA各主要方法对于组织因素考虑的不足,提出了HRA组织定向的必要性和基本原则.在提出组织定向的假设条件基础上,建立了HRA(A、B、C类事故)与核电厂相关特定组织之间的映射模型.     

Cascade-based attack vulnerability on the US power grid

The vulnerability of real-life networks subject to intentional attacks has been one of the outstanding challenges in the study of the network safety. Applying the real data of the US power grid, we compare the effects of two different attacks for the network robustness against cascading failures, i.e., removal by either the descending or ascending orders of the loads. Adopting the initial load of a node j to be L_j=[k_j(Σ_mΓjk_m)]^α with k_j and Γ_j being the degree of the node j and the set of its neighboring nodes, respectively, where α is a tunable parameter and governs the strength of the initial load of a node, we investigate the response of the US power grid under two attacks during the cascading propagation. In the case of α<0.7, our investigation by the numerical simulations leads to a counterintuitive finding on the US power grid that the attack on the nodes with the lowest loads is more harmful than the attack on the ones with the highest loads. In addition, the almost same effect of two attacks in the case of α=0.7 may be useful in furthering studies on the control and defense of cascading failures in the US power grid.