Taxomomy of Deviations to Prevent Safety-Related Oversights

当功能单元偏离正常时，就会发生系统故障。如果系统设计者能够列举功能单元的潜在偏差，这些故障就可以减少。基于可能性和严重性，有些偏差可以忽略不计。其他的应该通过设计修改来应对。本研究对安全相关偏差进行分类，以方便偏差的发现。1998年的研究使用标签来描述系统元素。例如，风扇的叶片可以被标记为“旋转部件”，从中可以发现无意停止和异常转速。总共列出了35个标签。开发了一个交互式计算机程序来帮助这一发现。1999年的研究重点是材料和功能。这些材料被归类为原材料。产品。服务物资和仓储物资。函数被划分为约束。转换。和一代。功能偏差包括执行失败和未能实现规范。从应力源（如力）的角度对材料失效进行分类。扭矩。热量。温度。和压力。对于汽车，可以发现后燃偏差。

System failures occur when functional units deviate from normalcy. These failures can be decreased if system designers can enumerate potential deviations of functional units. Some deviations can be neglected based on possibility and seriousness. and others should be coped with by design modifications. This study classifies safety-related deviations to facilitate discovery of the deviations.The 1998 study uses labels for characterization of system elements. For instance, a blade of a fan can be labeled as a "rotating part" from which inadvertent stoppage and abnormal rotation rate can be found. A total of 35 labels are listed. An interactive computer program is developed to aid the discovery.The 1999 study focuses on materials and functions. The materials are grouped into raw materials. products. service materials and storage materials. The functions are classified into constraint. transformation. and generation. Functional deviations include execution failure and failure to achieve specifications. Material failures are classified from points of view of stressors such as force. torque. heat. temperature. and pressure. An after-burning deviation can be found for automobiles.