Use of fuzzy sets in developing code risk factors

Fuzzy set theory is used to produce risk factor values for a building code. Working through reliability indices, a transformation is developed to convert estimates of relative social importance of a building into code load factors. The importance estimates are found by surveying knowledgeable members of society or playing their roles, and by using fuzzy set theory to combine their views according to their significance. An extension, again using fuzzy set theory, brings in the use of multiple criteria on which to base judgements. An example gives risk factors close to those in an existing code.     

A new wide area information based power system out-of-step oscillation detecting and oscillation center tracking scheme

A new out-of-step oscillation detecting and oscillation center tracking scheme based on the wide area information obtained from phasor measurement units (PMU) is proposed in this paper. In this scheme, the out-of-step oscillation is detected by the change rate of phase angle difference between bus voltage and system current, and the oscillation center tracking is completed by analyzing the phase angle relation between terminal bus voltages of electrical components and the system current. The scheme is easy to implement, and the tracking result is not affected by the changes of system structure and operation modes. Even in the complicated situations that the impedances of the whole system are nonuniform and the equivalent system potential amplitudes are not equal, it can still work well. The simulation results on PSCAD prove it is efficient. Utilizing the tracking results, a new out-of-step splitting criterion is given with which the splitting section can be determined dynamically according to the real-time operation state of power system.     

缺陷管道适用性评价技术研究进展

总结了近年来缺陷管道适用性评价技术的研究情况,随着断裂力学与计算机软件技术的不断发展,缺陷管道适用性评价技术也逐渐趋于完善。建立科学的适用性和完整性评价技术体系对我国油气管道的安全长期运行有着重要的意义。     

论我国等同采用国际风险管理标准的必要性

日前,国际标准化组织ISO正式发布了用于风险管理的国际标准ISO 31000:2009《风险管理——原则与指南》。该标准是在经济全球化的新环境下,"特定事件"和"特定法规"的基础上产生的,体现了世界范围内风险管理的最新理论和最佳实践。在全球金融危机尚未结束的今天,该标准的发布具有重要意义。本文从6个方面论述了我国"等同采用"ISO 31000:2009标准的必要性,并指出我国尽早"等同采用"该标准既有实践的基础,又有现实的意义。     

汽车门框上条制件拉弯成形模具设计简

汽车门框、窗框多由各种复杂截面型材弯曲成形后焊接而成，型材截面复杂，并且形状多为空间三维曲面，该类复杂截面型材的高精度弯曲成形是制造汽车门框和窗框的关键技术。通过分析某汽车门框上条制件的成形工艺特点，综合比较各种弯曲方式后选取了张臂式拉弯成形工艺，并设计了拉弯成形模具、切断机构、冲孔及辅助成形装置，利用该模具可以成形出符合制件质量要求的车门框上条工件。     

TARGET LEVELS IN TRAFFIC SAFETY ANALYSIS

The concept of target based traffic safety investment is discussed. A procedure is developed to establish the optimum target level [reduction in accident frequency, rate, or risk] that can be achieved when the expected cost of the countermeasure(s) and the expected cost of accidents is considered. Expected level of safety without countermea-sure and effectiveness of countermeasure are both treated as random variables, and it is shown that the optimum target is dependent on the form of the probability distribution, its parameters, and the ratio of accident cost to countermeasure cost. Application of the procedure to routine safety analysis and management is demonstrated using simple numerical examples.     

带式输送机弯曲段曲率半径的确定

通过输送机平面转弯段的受力分析,改进了平面转弯带式输送机转变处的布置结构,经使用,输送带在运行至弯曲段时能自动进行居中调节,效果较好。     

渡槽支撑框架在罕遇地震下的非线性时程分析

采用截面纤维模型对南水北调中线工程中的某典型渡槽的支撑框架结构进行了罕遇地震作用下的弹塑性动力时程分析,分析结果表明,该渡槽在罕遇地震作用下,没有明显的薄弱部位,最大层间位移角在限值以内,具有良好的抗震性能。     

AHP法在水利工程设计方案优选中的应用

以水利工程中某水库除险加固为例,采用层次分析法(AHP)对工程存在的风险进行分析。根据模型中各层次因素的相对重要性差异,定量表示客观现实情况,通过计算确定每一层次全部因素相对重要性权值,得到了各方案相对最高层目标的重要性次序组合权值,为定性问题的定量解决提供了理论依据和方法。计算结果表明:应用AHP法确定方案二最优。     

Activation cross sections of the Yb(p,xn)Lu reaction for indirect production of the therapeutic radionuclide Yb

Activation cross sections of the ^natYb(p,xn)¹⁶⁹Lu reaction have been measured for the first time up to 70 MeV to investigate the production possibility of the radionuclide ¹⁶⁹Yb through decay of its parent ¹⁶⁹Lu. The cross sections were measured using the stacked foil irradiation technique and gamma spectrometry. The experimental data were compared with the results of the ALICE-IPPE theoretical model code. Different production routes were compared for the internal radiotherapy related radioisotope ¹⁶⁹Yb. Above 30 MeV proton energy the integral yield of the ^natYb(p,xn)¹⁶⁹Lu reaction is higher than that of the earlier investigated ¹⁶⁹Tm(p,n)¹⁶⁹Yb, ¹⁶⁹Tm(d,2n)¹⁶⁹Yb, ^natEr(α,xn)¹⁶⁹Yb, ^natYb(α,x)¹⁶⁹Lu and ^natHf(p,x)¹⁶⁹Lu reactions at the equivalent particle energies.