Design Techniques for Functional System Safety - Report Example

Literature Review Design techniques for functional system safety Literatures on design techniques for functional system safety in human factors have become multifaceted. The multiplicity in understanding design techniques of the concept have been approached by first assessing different analysis tools available to perform hazard analysis for each program [1]. However, analysis tools for dealing with functional system safety in human factors needs to understand the wider meaning of human factor. Human factors are a multidisciplinary effort that help in the generation and completion of information regarding human limitations and abilities and apply that information to software, equipment systems, procedures or facilities [2, 3]. It therefore implies that literature review on the tools for analysis signify methodology and or approach of analyzing human factors as they concern functional system safety. While there are different analysis tools such as preliminary hazard analysis, HAZOP and CHAZOP, functional failure analysis or event tree analysis. The review considers three different tools which are Fault Hazard Analysis (FHA), Failure Mode and Effects Analysis (FMEA) and Management Oversight and Risk Tree (MORT). This report will begin by critically reviewing the three analysis tools in connection to human factor and functional system safety. Secondly, the report will provide detailed discussion on factors that should be considered in the application of the three analysis tools. Consideration on human factors means having a system designed to ensure that it only has the acceptable risk during the operations [4]. Beginning with Fault Hazard Analysis, this tool is a fit-for-purpose tool in understanding systems that will be designed to accommodate acceptable risk or that which considers human factor in operation [5]. According to the finding, Fault Hazard Analysis is both qualitative and quantitative tool that will ensure there is comprehensive investigation of sections and sub-sections of a system so that hazard modes, causes of these risks and the possible effects of the risks or hazards are considered for safety human operations. On the other hand, these tools can be assessed differently. First, researchers consider human factors as aspects that should be given to a system before it is put into use [6, 9]. That is, human errors that are given consideration in the system design processes and procedures. Relating this view to the tool, understanding the extent to which systems can disregard human factor depends on effects analysis [3, 17]. A comprehensive analysis has to be conducted to understand the depth to which a system cannot conform to basic human error. Fault Hazard Analysis is an approach that attempts to provide answers to questions such as, what are the documented effects of the failure, how frequent will the system fail or what is likely to cause its fail [8, 11]. Research conducted recently conceptualized the applicability of the tool in system safety [10, 14]. In their argument they considered human factor and related it to the propensity of an error being committed when a five-percent, 5K (plus or minus 250 ohm) resistor is operated by human beings. The research found that with Fault Hazard Analysis, there is a possibility to understand a functional failure possibilities failing short or open and on the other hand, there is out-of-tolerance modes which could include too high or too low a resistance. While the experiment conducted mimicked fault tree analysis and that the tool simply replicated fault tree analysis, FHA differs in the sense that when it is used to understand system safety and human factors it even provides preliminary information such as certain system features like human operational constraints, success and failure boundaries of different systems, system mission and realistic and probabilistic modes and measure of system’s failure or hazard occurrence. Recent review of Fault Hazard Analysis on failed systems/projects such as QantasLink flight QF1466 have given different perspective on how engineers can relate human factors and system safety in the design of different machines or system (12, 13; 15). Fault Hazard Analysis provides an opportunity to understand schematics, functional diagrams, specific drawings of the system and subsystems so that these components help to determine interrelationship between the component of the system and human operation. This tool predicts chances of human error commissions and omissions on a given system or components of systems. In most cases, it is the failure of a given section or component of a system that produces complete failure of the system. It therefore means that if Fault Hazard Analysis provides possibilities of understanding how human errors and omissions should be factored in the design of these systems. Failure Mode and Effects Analysis (FMEA) is the second design techniques used in functional system safety designs when predicting effects of human factors in a system. The approach in generating FMEA borrows much from FHA as it also entails listing all the low level functions or components then by examining system block diagrams or schematics, the function of every component of is identified and related to possible human error. In the design of systems that conform to different attributes of human factors, analysis by FMEA will help in the understanding of how figure of merit can be added systems [17]. Engineers usually perform this analysis to understand the safety, reliability and supportability of the systems if used or when all human factors that are likely to cause failures or accidents are given consideration (14, 18). FMEA is a tool needed in the design of different systems as it acts as hazard control emanating from errors committed or omissions from human beings. Unlike other analysis tools such as Fault Tree, FMEA has the ability to identify specific hazard that are likely to be committed by human beings as they isolate possible or probable causes based on their priorities or how they are likely to be committed when human beings are left to handle the system. Recent design of robotic machines shows that FMEA is a comprehensive strategy of understanding and giving room to human factors when designing systems because the tool can be applied bottom-up or top-down. FMEA considers operational procedures, failures as a result of these failures, and transient conditions in the list of hazard causes. Nevertheless, researches have also considered challenges faced by FMEA in the analyses of possible failures or chances of hazards caused by human error [19, 20]. FMEA majorly deals with software and hardware and for that case; it is generated from multifaceted sets of questions compared to other analysis tools such as FHA; ‘if this software fails, what is the effect will there be on the system, can it be detected? Will the problem cause further problems to the system?’ It is therefore clear that from these questions, FMEA is particularly not concerned with human factor but failure of either hardware or software. However, positions held by in this argument do not apply in all cases of design procedures for ally systems [21]. The study found that FMEA is critical in understanding or predicting human errors since it can be performed at functional or hardware or software level and in most cases, are combination of the three. This argument has been supported by different studies that agree that FMEA is able to characterize the results of possible human related failures and hazards [1, 5]. Consideration of human factors or errors in the design of system can be analysed using Management Oversight and Risk Tree (MORT). MORT is a comprehensive analysis approach used systematically analyse possibility of an accident that can be caused by human operations of systems [7, 22]. The analysis is conducted to examine and determine comprehensive details regarding the process and accidents contributors when systems are operated. Systems are supposed to be design in a manner that they are universally friendly to human use [8]. It is for this reason that MORT is a risk-based decision analysis efficient in understanding different components of a system so that a rational decision is made especially when people handle complex situations. Recent studies have attempted to evaluate effectiveness of MORT with regard to the need for periodic system inspection, procedures, operation or process [22, 23]. Conclusions that were made from these researches is that MORT is a tool that is effective in providing safety review assessment to a system as it provides designers a possibility of identifying system conditions or evaluation of operators’ likelihood of errors, hazards or associated maintenance. This view is in tandem with different researches who found that MORT provides assessment for designers to brainstorm or test a theory in where actual implementation could have catastrophic results when systems are operated by human [23]. While still on the assessment of the effectiveness of MORT, researchers agree that human-system performance considerations are in most cases, pegged or embedded into the project by integrating or incorporating human factors needs in the system specifications [22]. What this statement means is that the formulation of draft human performance requirements should be initiated during the early project phases and should continue through the implementation of the project. Based on this design requirement, researchers find MORT to be an essential tool which can easily and effectively integrate with the requirement. That is, they place essential ingredients into the project specifications so that human performance capabilities as well as limitations are incorporated in the project in a binding way. Studies compared MORT, Preliminary Hazard Analysis, and HAZOP and CHAZOP and the conclusion was that unlike Preliminary Hazard Analysis and HAZOP and CHAZOP, MORT identifies how human performance and safety requirement considerations effectively influence the design processes and project specifications and how they are going to be accommodated for different users [2, 5]. Specifically, they can predict system failures or errors associated with; System maintainer and user skills Staffing constraints Training time available and cost limitations when dealing with informal or formal, and on-the-job skill development Acceptable levels of system and human performance especially when they are operated and maintained by the targeted populations Factors to consider when choosing application of design technique Design techniques to be applied in the assessment of system safety depend on the need to understand the causal factors. Causal factors are determinants that suggest the probable causes or origin of hazards in systems when these systems are handled by human [6]. Causal factors in machines and systems differ. Machines are always characterized by unique causal factors and specifically, causal factors may be subordinate or underlying causal factors linked with the subordinate but in some systems or machines it is both. When dealing with such machines, analysis approaches such as MORT, HAZOP and CHAZOP, Functional Failure Analysis, and Event Tree Analysis should be applied. System specification is another factor that has been found to determine the type of technique to be applied [5]. From a human usage and performance perspectives, the system specifications has been found to be having the most significant effects or impact on system design and safety. There is need to understand the mission performance and technical requirements for a system. To understand these aspects, the assessment needs to understand possible causes of hazard in an ascending order. That is, how human errors can cause hazard and the possibilities of such hazards spreading to other parts of the system. When there is need for these types of analyses then Zonal Hazard Analysis will be applied since it is cause-consequence approach. However, MORT and HAZOP and CHAZOP is ideal in such situation as they combine top-down and bottom-up technique thus suitable in understanding complex system and risks related to such systems. Total system performance is another factor that greatly determines the type of technique that will be used in analysis [9]. Total system performance is the probability that the whole system will perform correctly and according to specifications given. By this definition, human performance, factor and errors are considered as a component of the system. It therefore means that the technique used in the analysis should factor the possibilities of these components [12]. In such cases, studies advice that MORT and HAZOP and CHAZOP should be applied ahead of other techniques such as Zonal Hazard Analysis because these techniques assess changes and the effects of modifications from a baseline or starting point. What has been found is that these techniques ensure that system will be able to work from an engineering sense in a laboratory and the same efficiency and functionality maintained at a demonstration site and further when bought and operated by the targeted population. References [1] C. Rogers, Risk management in a dynamic society: a modelling problem. Safety science: Video Education Australasia, 2014. [2] L. Bass, P. Clements, and R. Kazman. Software Architecture in Practice, 2nd ed. Reading, MA: Addison Wesley, 2003. [E-book] Available: Safari e-book. [3] D. Ince, “A human error approach to aviation accident analysis: The human factors analysis and classification system”: Oxford Reference Online, http://www.oxfordreference.com. [Accessed: October 13, 2015]. [4] H. K. Edwards and V. Sridhar, "Analysis of software requirements engineering exercises in a global virtual team setup," Journal of Global Information Management, vol. 13, no. 2, p. 21+, April-June 2005. [Online]. Available: Academic OneFile, http://find.galegroup.com. [Accessed October 8, 2015]. [5] A. Rezi and M. Allam, "Human and management factors in probabilistic risk analysis: the SAM approach and observations from recent applications. Reliability Engineering & System Safety, Vol. 69,  Multidemsional Systems, C. T. Leondes, Ed. San Diego: Academic Press, 2009, pp. 133-180. [6] J. Riley, "The work process analysis model (WPAM). Reliability Engineering & System Safety," The Australian, p. 35, May 31, 2005. Available: Factiva, http://global.factiva.com. [Accessed October 8, 2015]. [7] J. Geralds, "Sega Ends Production of Dreamcast," vnunet.com, para. 2, Jan. 31, 2001. [Online]. Available: http://nl1.vnunet.com/news/1116995. [Accessed Sept. 12, 2004]. [8] W. D. Scott & Co, Information Technology in Australia: Capacities and opportunities: A report to the Department of Science and Technology. [Microform]. W. D. Scott & Company Pty. Ltd. in association with Arthur D. Little Inc. Canberra: Department of Science and Technology, 2004. [9] G. O. Young, "Systems engineering and analysis," in Plastics, 2nd ed., vol. 3, J. Peters, Ed. New York: McGraw-Hill, 2010, pp. 15-64. [10] N. Osifchin and G. Vau, "Power considerations for the modernization of telecommunications in Central and Eastern European and former Soviet Union (CEE/FSU) countries," in Second International Telecommunications Energy Special Conference, 2006, pp. 9-16. [11] O. B. R. Strimpel, "Computer graphics," in McGraw-Hill Encyclopedia of Science and Technology, 8th ed., Vol. 4. New York: McGraw-Hill, 2011, pp. 279-283. [12] K. Schwalbe, Information Technology Project Management, 3rd ed. Boston: Course Technology, 2004. [13] L. Vertelney, M. Arent, and H. Lieberman, "Two disciplines in search of an interface: Reflections on a design problem," in The Art of Human-Computer Interface Design, B. Laurel, Ed. Reading, MA: Addison-Wesley, 1990. Reprinted in Human-Computer Interaction (ICT 235) Readings and Lecture Notes, Vol. 1. Murdoch: Murdoch University, 2005, pp. 32-37. [14] M. N. DeMers, Fundamentals of Geographic Information Systems, 3rd ed. New York: John Wiley, 2005. [15] E. P. Wigner, "Theory of traveling wave optical laser," Physical Review, vol.134, pp. A635-A646, Dec. 2012. [16] J. U. Duncombe, "Infrared navigation - Part I: An assessment of feasibility," IEEE Transactions on Electron Devices, vol. ED-11, pp. 34-39, Jan. 2013. [17] M. Bell, et al., “Measuring safety climate: identifying the common features. Safety science”, Occasional Paper Series 02-A. Canberra: Department of Education, Science and Training, 2002. [18] T. J. van Weert and R. K. Munro, Eds., Informatics and the Digital Society: Social, ethical and cognitive issues: IFIP TC3/WG3.1&3.2 Open Conference on Social, Ethical and Cognitive Issues of Informatics and ICT, July 22-26, 2002, Dortmund, Germany. Boston: Kluwer Academic, 2003. [19] I. S. Qamber, "Flow graph development method," Microelectronics Reliability, vol. 33, no. 9, pp. 1387-1395, Dec. 2001. [20] P. H. C. Eilers and J. J. Goeman, " Dekker, S. (2004). Ten questions about human error: A new view of human factors and system safety," Bioinformatics, vol. 20, no. 5, pp. 623-628, March 2004. [Online]. Available: www.oxfordjournals.org. [Accessed Sept. 18, 2004]. [21] A. Holub, "Is software engineering an oxymoron?" Software Development Times, p. 28+, March 2005. [Online]. Available: ProQuest, http://il.proquest.com. [Accessed May 23, 2005]. [22] H. Zhang, "Delay-insensitive networks," M.S. thesis, University of Waterloo, Waterloo, ON, Canada, 1997. [23] AlphaCom Communications introduces VMSK technology,” The Business Journal Online, May, 2000. [Online]. Available: http://www.business-journal.com/LateMay00/Alpha.html. [Accessed: May 2, 2000]. Read More

Relating this view to the tool, understanding the extent to which systems can disregard human factor depends on effects analysis [3, 17]. A comprehensive analysis has to be conducted to understand the depth to which a system cannot conform to basic human error. Fault Hazard Analysis is an approach that attempts to provide answers to questions such as, what are the documented effects of the failure, how frequent will the system fail or what is likely to cause its fail [8, 11]. Research conducted recently conceptualized the applicability of the tool in system safety [10, 14].

In their argument they considered human factor and related it to the propensity of an error being committed when a five-percent, 5K (plus or minus 250 ohm) resistor is operated by human beings. The research found that with Fault Hazard Analysis, there is a possibility to understand a functional failure possibilities failing short or open and on the other hand, there is out-of-tolerance modes which could include too high or too low a resistance. While the experiment conducted mimicked fault tree analysis and that the tool simply replicated fault tree analysis, FHA differs in the sense that when it is used to understand system safety and human factors it even provides preliminary information such as certain system features like human operational constraints, success and failure boundaries of different systems, system mission and realistic and probabilistic modes and measure of system’s failure or hazard occurrence.

Recent review of Fault Hazard Analysis on failed systems/projects such as QantasLink flight QF1466 have given different perspective on how engineers can relate human factors and system safety in the design of different machines or system (12, 13; 15). Fault Hazard Analysis provides an opportunity to understand schematics, functional diagrams, specific drawings of the system and subsystems so that these components help to determine interrelationship between the component of the system and human operation.

This tool predicts chances of human error commissions and omissions on a given system or components of systems. In most cases, it is the failure of a given section or component of a system that produces complete failure of the system. It therefore means that if Fault Hazard Analysis provides possibilities of understanding how human errors and omissions should be factored in the design of these systems. Failure Mode and Effects Analysis (FMEA) is the second design techniques used in functional system safety designs when predicting effects of human factors in a system.

The approach in generating FMEA borrows much from FHA as it also entails listing all the low level functions or components then by examining system block diagrams or schematics, the function of every component of is identified and related to possible human error. In the design of systems that conform to different attributes of human factors, analysis by FMEA will help in the understanding of how figure of merit can be added systems [17]. Engineers usually perform this analysis to understand the safety, reliability and supportability of the systems if used or when all human factors that are likely to cause failures or accidents are given consideration (14, 18).

FMEA is a tool needed in the design of different systems as it acts as hazard control emanating from errors committed or omissions from human beings. Unlike other analysis tools such as Fault Tree, FMEA has the ability to identify specific hazard that are likely to be committed by human beings as they isolate possible or probable causes based on their priorities or how they are likely to be committed when human beings are left to handle the system. Recent design of robotic machines shows that FMEA is a comprehensive strategy of understanding and giving room to human factors when designing systems because the tool can be applied bottom-up or top-down.

FMEA considers operational procedures, failures as a result of these failures, and transient conditions in the list of hazard causes.

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