CC BY
9
The branch of fault tree for the case of dangerous icing must take into account scenarios that may lead to LOSA accident. In all cases of icing the metacentric height and stability lever arms are reduced.
The simplest scenario is when the amount of accrued ice is so large, that the metacentric height becomes negative and the initial part of the stability lever arms curve is also negative. With the reduction of the stability characteristics probability of LOSA may increase even by two to three orders.
More complex scenarios, where human factor must be considered, are also possible. Accrued ice should be removed by the crewmembers. However it is not always possible. If the ship is sailing against the wind and waves in severe storm, when the conditions are most favourable for ice accretion in the bow quarters, it is not possible to send crew towards the bow in order to remove ice. It would be necessary to turn the ship to sail with the wind. Such manoeuvre is, however, dangerous and it may cause ship capsize, in particular if the removal of ice was started to late when the stability of the ship was already low.
Examples of fault tree and event tree for the case of dangerous icing are shown in Figure 4 and Figure 5. It is obvious that two conditions are necessary for ice accretion: the ship must be in the area where icing is possible, and also weather conditions must allow that (negative temperatures, wind). Situation, where the ship is in the area where icing is possible and there are unfavourable weather conditions depends on sailing route, then on ship owner request or on decision of master who ignored the danger and makes no attempt to avoid the dangerous area.
Attaching probabilities to various events that appear in the fault tree and estimating on this basis probability of the top event should be accomplished mainly using expert's opinions. In some cases statistical data may be available in ship owners data bank. Review of the literature reveals that in case of icing such data were collected by some research institutes, but generally they refer to the amount of accrued ice in various conditions. Statistical data on effect of operational measures in case of icing are not available and probabilities could only be assessed o upon studying as many as possible real situations and accidents.
7. Risk control options and acceptability of risk
Considering risk control options three levels of action may be necessary if the risk index is over, say, grade 3.
icing removed
©
turn to following wind to remove ice successful
©
LOSA
dangerous icing
not successful
critical stability
LOSA
weather improved
©
sufficient stability
©
Figure 5. Event tree for severe; icing vonsequences
Grade 8-9 - action to eliminate the hazard or hazardous situation (intolerable region)
Grade 6-7 - action to control or reduce the probability of the hazardous situation (tolerable region)
Grade 4-6 - action control the hazard, desirable, if cost effective
This problem is not elaborated because lack of space. Reference is made to [14] where risk acceptability and risk control options are discussed more widely.
8. Conclusion
Application of risk analysis may be quite complex task, requiring employment of large group of experts and analysts, nevertheless, is realistic. Risk analysis would reveal weak points in ship design, but also, which is more important, in management and operational procedures. It can also show where barriers have to be put in order to control risk. Risk analysis must be viewed as advantageous in comparison with the traditional prescriptive approach, although the last being much simpler, will certainly be used in majority of cases. Obviously, because of high effort and cost of performing risk analysis, in practice it could only be applied in cases of highly sophisticated large ships or ships with novel design features.
References
[1] Aksiutin, L. P. & Bliagoveschensky, S. N. (1975). Avarii sudov ot potieri ostoichivisti, Sudostroenye, Leningrad.
[2] Alman, P. R., Minnicck, P. V., Sheinberg, R. & Thomas III, W. L. (1999). Dynamic capsize vulnerability: reducing the hidden operational risk. SNAME Annual Meeting, paper No.10.
[3] Chantelauve, G. (2005). On the use of risk analysis in maritime certification and classification. Advances in Safety and Reliability ESREL 2005, Vol. I p. 329.
[4] Cleary, W. A. (1975). Marine stability criteria. Proceedings of the 1st International Conference on Stability of Ships and Ocean Vehicles, Glasgow.
[5] Ericson, A., Persson, J. & Rutgerson, O. (1997). On the use of Formal Safety Assessment when analyzing the risk for cargo shift in rough seas. RINA International Conference Design and Operation for Abnormal Conditions, Glasgow.
[6] Halebsky, M. (1989). System safety engineering as applied to ship design, Marine Technology, Vol. 26.
[7] Hokstad, P., 0ien, K. & Reinertsen, R. (1998). Recommendations on the use of expert judgement in safety and reliability engineering studies. Two offshore case studies. Reliability Engineering & System Safety, Vol. 61, No.1/2.
[8] IMO (1966). Analysis of intact stability casualty records of cargo and passenger vessels. Joint report submitted by the Federal Republic of Germany and Poland. Doc. IS VI/3.
[9] IMO (1966a). Analysis of intact stability records of fishing vessels. Joint report submitted by the Federal Republic of Germany and Poland. Doc. PFV IV/2.
[10] IMO (1985). Analysis of intact stability casualty records. Submitted by Poland. Doc. 30/4/4 and SLF/38.
[11] IMO (2002). Guidelines for Formal Safety Assessment (FSA) for use in the IMO rule-making process. Doc. MSC/Circ.1023; MEPC/Circ.392.
[12] IMO (2006). Revised Intact Stability Code Prepared by the Intersessional Correspondence Group. Submitted by Germany. Doc. SLF 49/5.
[13] Kobylinski, L. (1984). Philosophishe und Hydrodynamische Probleme der Internationalen Kenterkriterien von Sciffen. Intern. Schiffstechnische Symposium, Rostock.
[14] Kobylinski, L. (2004). Application of the FSA methodology to intact stability criteria. Marine Technology Transactions, Vol. 15, pp 319-329.
[15] Kobylinski, L. (2005). Appraisal of risk assessment approach to stability of ships. International Workshop on Ship Stability, Istambul.
[16] Kobylinski, L. (2006). Alternative stability requirements based on system and risk approach. Rio de Janeiro.
[17] Manum, I. A. (1990). What have guided international activities on intact stability so far? Proceedings of the 4th International Conference on Stability of Ships and Ocean Vehicles, Naples.
[18] McTaggart, K. & de Kat, J. O. (2000). Capsize risk of intact frigates in irregular seas. SNAME Annual Meeting, No. 8.
[19] Schauer, T., Romberg, B., Jiang, Ch. & Treasch, A. W. (1995). Risk assessment of small fishing vessel trap net operations. Marine Technology, Vol. 32. No. 4.
[20] Spouge, J. (1996). Safety assessment of passenger/ro-ro vessels. RINA Intern. Conference on the safety of passengers in ro-ro vessels. London.
[21] Sukhanov, S. I., Panov, V. V. & Lavrenov, I. V. (2003). Extreme ship's icing in the Black Sea. Arctic and Antarctic Research Institute, Russia No. 04-05-64306.
[22] Bekke, E. C. A., van Daalen, E. F. G., Willeboordse, E. J., Boonstra, H., Keizer, E. W. H. & Ale, B. (2006). Integrated safety assessment of small container ships. 8th Intern. Conference on Probabilistic Safety Assessment and Management, New Orleans.
[23] U. S. Coast Guard (1995). Prevention through people. Quality Action Team Report.
RELIABILITY WAVE IN LIGHT OF THE NANO
DEVELOPMENT
Kuo Way
The University of Tennessee, Knoxville, TN, USA
Keywords
stress test, nano technology Abstract
This talk is based on the Editorial of IEEE Transactions on Reliability, December, 2006 and discusses a framework for applying reliability principles and practices to the emerging nano technology fields.
1. Introduction
To Build for the Future, we must achieve major advances related to reliability in addition to exploring and discovering interdisciplinary connections in important cutting-edge research areas. The technologies for today's design and manufacturing have for some time been steadily moving from the realm of the micro- to the nano-scale, but advancements in reliability have not kept up with the pace!
2. Reliability and nano technologies
New ideas and connections stimulated by modern advancements are appearing in the bio, energy, and computing fields while design, manufacturing, and reliability modelling are being left behind. For example, fabrication technologies for integrated circuits are on the edge of the nano scale, with a gate length of less than 100 nm in the most advanced microprocessors [1], [2], and some capacitors are already available on a scale of 1-2 nm equivalent oxide thickness [3]. In particular, micro-electromechanical (MEM) devices are integrating mechanical motion with electronics on the micro-scale, and thereby, generating novel approaches to applications and new industries. Furthermore, we are already developing the scientific base - nano theory, fabrication science, materials sophistication, and manufacturing capabilities - for a full-scale assault on nanotechnology. But we must ask if the manufacturing community is ready for producing nano devices, and whether the reliability community is ready to certify proper use of these nano devices-based systems.
Even more fundamentally, we must ask: what is the meaning of reliability for systems that use nano or new technologies, and how do we interpret this meaning in practice? For example, are consumers likely to be satisfied with high cost plasma TVs with an estimated 5-7 year expected life? As reliability engineers, we must not only bridge multiple cutting-edge disciplines to complement the technology-rich industries, but also be leaders in guaranteeing that high tech products and systems perform to acceptable modern standards.
The activities associated with nano development are expected to enhance international understanding and collaboration for a bright, fast-moving future in design, manufacturing, and industrial innovation. Reliability research and development work in the past has contributed to the industrial world by enhancing the quality of the products. The academic community has also played a critical role in the process by making fundamental discoveries that have contributed to the realization of this quality enhancement. Examination of the numerous issues and papers published by IEEE Transactions on Reliability over the past 55 years clearly demonstrates the significance of the academic role in the advancement of our field.
However, it is also important to recognize that recently our profession seems to have stagnated in terms of making new contributions to the emerging technologies, electronics and otherwise. How much have we contributed to the reliability of the existing, reliable MEMS and nano devices?
Although reliability is very much a central concern in nano technologies, the reliability community has made little progress in developing new methodologies and standards that are applicable in this realm. Instead, we seem to be leaving that up to the industrial practitioners who had not been rigorously trained in reliability.
2.1. Four challenges
There appear to be four major challenges related to nano electronics that currently face the field of reliability: identification of the failure mechanisms, enhancement of the low yields of nano products, management of the scarcity and secrecy of the available data, and preparation of reliability practitioners and researchers for keeping up with the nano era.
2.1.1. Identification of the failure mechanisms
As new generations of nano electronics are invented almost daily, we become less familiar with the failure mechanisms of these devices, and the reasons behind the failures. With our existing knowledge, we often can not identify the correct faults; and in fact, we are likely to see many no-fault-found failures. Nor can we manufacture reliable products with full confidence.
Shorting (e.g., inadequate etching processes or insulating structure), and opening (e.g., electro migration of nano wires) of interconnect lines caused most of the failures in traditional electronic products. Will the new trend be toward more open / resistive related failures because of the new materials, large number of contacts/vias, higher functional speeds, new circuit design rules, and other factors? Identifying the failure mechanisms in nano electronics will have impact on determining the right strategies for life testing, highly accelerated stress screening (HASS), burn-in screening for reliability enhancement, reliability prediction, warranty duration and conditions, and many other processes. The hurdle in comprehending nano failure mechanisms seems greater than previous hurdles that dealt with similar issues in the past. We are unsure as to whether much of the knowledge that is based on past technologies is still valid for reliability analysis. Understanding the failure mechanisms of nano electronics is critical for preparing system designers to better utilize nano devices, and design better fault tolerant systems.
2.1.2 Enhancement of the low yield in nano products
The development of nano devices, such as those used in commercial and military systems, has generated a lot of excitement. However, the low yield rate [2], [4] of current nano devices, typically 10% or lower, is very troublesome. Low yield makes production extremely expensive, and the product's expected life uncertain. The low yield also creates a challenge for both the designers and scientists to find better materials and fabrication tools. At the early nano product fabrication stage, low yield is actually a technology agenda, rather than a logistics issue, although some believe that scheduling & logistics optimization can improve the yield. Although low yield is a fundamental material-related problem that modern reliability engineers must face in order to improve yield at an affordable cost, it is also a design issue because many modern systems are increasingly complex, and the product life cycles are often too short to achieve better yield.
2.1.3. Management of the scarcity and secrecy of available data
Manufacturers have always kept reliability and yield data secret, or not kept it at all. The problem is compounded by the scarcity of failure data, which makes it almost impossible to use traditional reliability analysis tools and statistical inference to make useful predictions. Therefore, experienced analysts have to perform in-house analyses using ad hoc approaches. Despite that many statisticians have in the past been against using the Bayesian approach because of the "lack of credibility" associated with it, we are now forced to be more Bayesian than ever before.
In fact, many engineers have always used the Bayesian approach successfully, although in the eyes of the theoreticians, their methodology has not been mathematically rigorous. It is important to note that the Bayesian approach is more than a tool--it is also a philosophy. Many academic statisticians have contributed to theories of reliability; on the other hand, it is perhaps more obvious that the empirical approaches used by reliability engineers have improved numerous products and systems for consumer use. We predict that the Bayesian approach will be even more frequently utilized in the nano era as product life cycles based on new technologies become even shorter, and it is becoming impossible to obtain sufficient data before a new product requires reliability assessment. The other possibility, with great challenge too, is to predict reliability using the computer-aided tools, based on the physical properties of the nano systems. Here the reliability calculation will be physics-based.
Given the useful life of many products is short (not necessarily because of reliability concerns, but more because of using the new nano technologies which may provide the users with more features) before the customers express an interest in using the new products, is the traditional life-cycle analysis still valid?
2.1.4. Preparation of Reliability Practitioners and Researchers for Keeping up with the Nano Era
As society adapts to the nano and bio world, and we integrate these technologies into more complex systems, it becomes ever more important to hold products accountable, and to require better quality and reliability from them. To cope with this challenge, modern statisticians and reliability engineers need to re-engineer themselves to learn about the nano world. In order not to be left behind the modern society in terms of technology advancement, researchers must become less bogged down in the old, purely academic exercise of separating hypothetical problems from real world problems, and applying only mathematically rigorous approaches.
Reliability academicians need to become more problem-driven than hypothesis-driven. Reliability faculty must update their course materials as well. Biostatisticians appear to be doing a better job of dealing with the fast-changing bio world than we are doing in dealing with the nano electronics. Perhaps they can serve as role models. Therefore, in order to be relevant, reliability specialists need to be versed in modern technology; reliability analysis, and modelling for the nano technologies will have to be more physics-based. At the system level, we need to learn how to integrate nano technologies into larger systems so that interfaces between technologies are reliable and better understood.
3. Conclusion
High reliability and high yield are necessary to guarantee the advancement & utilization of micro, and nano products. Reliability researchers need to be energized to tackle the very real problems that we face in the nano-rich world. Reliability practitioners and researchers need to understand the paradigms and issues, such as those listed above, involved in the nano technologies.
Keeping systems simple is important; otherwise we will add more uncertainties to the compatibility problems [5], [6]. The research dealing with the understanding and application of reliability at the nano level has demonstrated its attraction and viability. Optimal system design that considers reliability within the uniqueness of nano systems has hardly been reported in the literature, and hence deserves a lot more attention. We must share our reliability experience with designers so that, in the future, they can consider other options (e.g., to be more fault-tolerant) when dealing with large, complex systems using nano technologies.
I anticipate that our society will expect reliability specialists to take heavy responsibility for utilizing & certifying the use of nano technologies. To that end, we must break out of this period of disciplinary stagnation, and redouble our efforts to prepare ourselves to advance the state of the art of the nano technologies.
References
[1] The National Academies Keck Futures Initiative Nanoscience and Nanotechnology Steering Committee. (2004). Designing Nanostructures at the Interface between Biomedical and Physical Systems. National Academies Press, 106 pp., Washington, DC.
[2] The National Academies Press. (2002). Implications of Emerging Micro- and Nanotechnologies, 251 pp., Washington, DC.
[3] Yue Kuo. (2006). Thin Film Nano & Microelectronics Research Lab. Texas A&M University.
[4] Way Kuo & Kim, T. (1999). An Overview of Manufacturing Yield and Reliability Modeling for Semiconductor Products. Proceedings of the IEEE, 87(8), 1329-1346.
[5] Way Kuo & Prasad, V. R. (2000). An Annotated Overview of System Reliability Optimization. IEEE Transactions on Reliability, 49(2), 176-187.
[6] Way Kuo, Velaga, R., Tillman, F. A. & Hwang, C. L. (2001). Optimal Reliability Design: Fundamentals and Applications, 411 pp., Cambridge University Press, U.K
RISK ASSESSMENT RELATED TO INFORMATION UNCERTAINTY COMPONENTS
Rosická Zdena
University of Pardubice, Faculty of Restoration, Litomysl, Czech Republic
Keywords
assets, data, experience, information, knowledge management, organization, tacit and explicit knowledge Abstract
Both organization and individuals deal with and manage knowledge. Considering the basic approach, we distinguish two principal clusters: tacit and explicit knowledge. The knowledge management is targeted at making the organization knowledge operation more effective and providing the right people with relevant information at the right time. Knowledge and information uncertainty components have become one of crucial assets of any company or organization. Their crucial potential consists in smart knowledge management handling, proficiency and art to fit the risky market needs better than competitors.
1. Introduction
Mankind has been working with knowledge from beginning to everlasting end and is trying to find the way how to manage it. The difference consists in technological and scientific level and maturity of current generations. Technological level makes possible for broad masses of public free access to knowledge, and, in addition, there are scientific branches, such as neurology, genetics, psychiatry and psychology that are able to initiate undreamt-of abilities of a human brain. Simultaneously the volume of knowledge rises undoubtedly fast and we need to search for methods and tools that can assist to sort out, classify and systematize the heritage of mankind's knowledge; however, at the same time we should try to eliminate the fact the knowledge is available but the individual who needs it does not know it, therefore it is unavailable.
The purpose and goal of knowledge management are targeted at three crucial phenomena:
• a person should keep at disposal the knowledge he needs,
• the knowledge should be available at the time he needs it,
• it should be nobody but the person who needs this knowledge indeed.
There are many approaches to knowledge and knowledge management. This tendency is remarkably evident in technologically advanced branches, e.g. communications. In fact, organizations in this field do not differ in technical utilities. In case they need to differ from other competitors, they have to attract customer and offer a different product or a product with higher added value, a higher quality product or a cheaper product. Whatever method they select in order to differ from others, they must be able to exploit and take advantage of knowledge available to be better and smarter than their competitors.
2. History of knowledge management
Knowledge management is a new discipline considering its systematic approach to knowledge. People tried to manage the knowledge since its very beginning; however, we can characterize it as more or less intuitive. Depending on needs, our predecessors emphasized various aspects of knowledge utilization. In the Stone Age people's knowledge was oriented at animals, plants, weather and tribe rules and habits. Knowledge passed in tacit form, orally and through non-verbal communication. Ancient Roman period is considered a foundation of intellectual property of mankind: mathematics, philosophy, geometry, astronomy, medicine and logic were developing extremely fast. Considering the approach to r preparation knowledge,
