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Designing a User-Friendly Manual
Published in Patricia A. Robinson, Writing and Designing Manuals and Warnings, 2019
Did you ever try to stretch the length of a school essay or research paper with a required minimum page length by restating the same information in different words? If so—and if your teacher was on the ball—you probably found the comment “Redundant!” scribbled in red ink along the margin. Or perhaps you find yourself editing out other people’s redundant expressions, such as “free gift,” or “brown in color,” a category of phrases a former colleague10 refers to as “dog puppies.” While redundant expressions can make for bloated writing, not all redundancies are bad. Consider redundant safety systems (a type of “fail-safe” engineering) that ensure that even if the first safety feature malfunctions or is disabled, a second system is in place to prevent injury.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Fail-safe and dead-man - These two terms are often encountered in studying the operation of clutches and brakes. Fail-safe means that the operating mechanism has been designed such that, if any element should fail to perform its function, an accident will not occur in the machine or befall the operator. Dead-man, a term from the railroad industry, refers to the control mechanism that causes the engine to come to a stop if the operator should suffer a blackout or die at the controls.
Implementing Use of Hydrogen as Fuel for Aircraft
Published in G. Daniel Brewer, Hydrogen Aircraft Technology, 2017
With the complete aircraft fuel system assembled, tests can be conducted which will permit accomplishment of the following objectives:Investigate aircraft tank filling procedures. Experimentally determine the preferred design of plumbing system and operational procedure which will permit refueling of aircraft tanks within specified time limits.Determine operational characteristics of an integrated design of an aircraft fuel system.Determine procedures for performing inspection and repair of LH2 system components.Determine effect of repeated flight cycles and fueling/defueling cycles on tank structure, insulation system, and fuel delivery system.Demonstrate the fail-safe features of the system by simulating failures.Provide a basis for writing design specifications and certification requirements for LH2 fuel systems and components suitable for aircraft service.
Fault-tolerant design and evaluation for a railway bogie active steering system
Published in Vehicle System Dynamics, 2022
According to [6], in the case of failure of one actuator during service the reaction of the controlled vehicle/system can be classified in two classes: Fail-active and Fail-safe. Fail-active means the system will be reconfigured if the failure is detected, to realise complete or partial function in a new mode. An example of fail-active design for a control system is provided by Mei [9]. However, in case an unpredicted or too severe failure mode takes place, it may be impossible to reconfigure the system. In this case, Fail-safe design of the system is more viable. Fail-safe design means the consequences of failures in the system are mitigated to an extent that guarantees the safe functioning of the system, although with a possible decrease of performance. This leads to the concept of fault-tolerance, i.e. the property of the system to operate safely after a fault has occurred.
Safety Criteria and Dependability Management Practices: A Case Study with I&C Systems of Prototype Fast Breeder Reactor
Published in Nuclear Technology, 2018
Srikantam Sravanthi, R. Dheenadhayalan, K. Madhusoodanan, K. Devan
All scram processing electronics are deployed with online self-diagnostics and subsequent fail-safe outputs in case of faults. Only one of the two voting logic circuits uses an inherently fail-safe design (PCSL). Inherently, fail-safe systems will automatically lead to a safe state in case of failures in the system. It does not require an additional diagnostic circuit. So these circuits have a lower unsafe failure probability since the periodicity of self-test is tending to zero and the issues arising out of failures in diagnostic circuitry do not exist. A failure mode effect analysis (FMEA) has to be used to assess the effects of each potential component failure on the system. This is performed by analyzing each component with all dominant failure modes as listed in Failure Mode/Mechanism Distributions in Ref. 21 and consequences of such failures on the system. IEC 60812 is the recommended standard for carrying out FMEA (Ref. 22).