Safety Assessment Using Fuzzy Theory

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Abstract

Uncertain input parameters may result from “fuzziness”, “randomness” or “fuzzy randomness”. With the use of fuzzy set theory, uncertain input parameters may be described mathematically as fuzzy variables or fuzzy random variables and may be integrated into safety assessment analysis. With the aid of α-discretization involving the multiple solution of special optimization problems, fuzzy input parameters are mapped onto the uncertain result set. If the deterministic input data are characterized by “fuzziness”, the fuzzy results are uncertain outcomes of the structural analysis; safety assessment may then be carried out using possibility theory. If the input parameters exist in the form of fuzzy random variables, the computed fuzzy failure probabilities may be used for safety assessment. A fuzzy 1st-order reliability method (FFORM) is proposed, which is capable of handling fuzzy as well as fuzzy random variables.

Control System Design Risk Assessment Using Fuzzy Logic

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Introduction

This manual describes a technique that can be used to assess the impact of the flight control system on aircraft configuration geometry. The primary purpose is to perform trade-off studies between different aircraft configurations in the preliminary design phases of development. It can also be easily automated and adapted for use in aircraft configuration optimization problems.
The underlying approach is to determine the control system structure that is needed to correct deficiencies in the dynamics of the aircraft. The complexity of the control system is assumed to measure the amount of risk associated with that aircraft (if it were built). Configurations that require a very simple control system architecture would incur only a small risk. Configurations with a very complicated control system would be assigned a higher risk.
The required control system architecture is determined using a set of fuzzy logic rules. These rules are developed using experience and knowledge about how control systems are designed. Using this approach, a control system is not actually designed for a given configuration under study. Only the required control system structure is determined. The final design of the control system would come after the final configuration has been selected and detailed aerodynamic and structural models are developed.
This report describes a procedure and rule base to determine the flight control design risk for the longitudinal axis of aircraft motion. Only one specification regarding aircraft flying qualities is considered. However, the rules and methods described in this report could also be expanded to include other design requirements and specifications.

Evaluation Of The Wildfire Ignition Risk By The Aid Of Fuzzy Logic

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The danger of destructive wildfires has become a major issue in the U.S. due to decades of fuel accumulation from fire suppression efforts. With more people moving closer to or living in the wildland-urban interface, the risk of wildfires has increased dramatically. Wildfire risk analysis is aiming at predicting when and where wildfires will likely occur, and measures can be taken in advance to reduce the number and the intensity of disasters. In general, wildfire risk analysis can be divided into ignition risk analysis and fire behavior risk analysis. This study focuses on an ignition fire risk analysis in Rabun County, Georgia. Four fire risk related factors — human activity, illumination, elevation and vegetation type — were derived from spatial datasets. Three of them were used as linguistic variables, and then fuzzy set theory and fuzzy inference were applied to these variables to model wildfire risk levels (low, possible, substantial and high). The final result is a thematic risk level map that suggests that fuzzy logic can be used as a powerful tool in the field of fire risk analysis to predict more interpretable risk levels for a certain area. Some advantages and disadvantages of using fuzzy logic over traditional approaches were also discussed in the paper.

Fuzzy Inference As An Approach To Safety Management System (SMS) Analysis

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ABSTRACT

Safety analysis is one of the major areas of Ship Management company activity that frequently comes face to face with a nontraditional problem of "measurements of safety". The question arises of how to estimate or measure the safety level? There is no doubt that, post accident,
a priori statistical analyses or Formal Safety Assessment are not effective instruments to apply in a real-time interval, especially in emergencies. The majority of problems are directly linked with the human factor, which is very difficult to formalize.
The safety analyses generally serve as decision aids. Wise decisions are essential in any safety
program. Human decisions depend on numerous factors that transcend requirements and physical response, and many of these can be captured mathematically using fuzzy logic.
Fuzzy logic is conceptually easy to understand in SMS applications. It is flexible. With any given SMS it's easy to massage or layer more functionality on top of it without starting again from scratch, for example: to incorporate ISPS Code procedures into the already working SMS. Fuzzy logic is tolerant of imprecise data and there is a lot of such data in shipping.
Fuzzy logic can model nonlinear functions of arbitrary complexity. Fuzzy logic can be built on top of the experience of maritime safety experts and it can be blended with conventional control techniques. The most impressive feature is that fuzzy logic is based on natural language.
The paper highlights some problems mentioned above and contains the research findings on evaluation of technical and human factor impact on safety at sea using fuzzy logic approach and applying such factors (linguistic variables) as safety, fatigue, OOW distractions, deficiencies, near misses, skill, level of education and training, technical failures, company policy/culture, etc.

Hazards Identification and Prioritization in Formal Safety Assessment Using Fuzzy Logic Theory

Jurnal dibawah ini tentang penilaian keselamatan dengan menggunakan teori fuzzy. Cukup mudah untuk dimengerti karena metodologinya jelas. Bagus untuk referensi tugas safety

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Hazards Identification and Prioritization in Formal Safety Assessment Using Fuzzy Logic Theory

Author: G. N. Dourmas; N. V. Nikitakos; M. A. Lambrou

Abstract

Formal safety assessment of ships has attracted great attention over the last few years. This paper, following a brief review of the current status of marine safety assessment is focused on the hazards identification (HAZID) and prioritization process, as the first step in the formal ship safety assessment. A multicriteria decision making framework which is based on experts’ estimation is then proposed for hazards evaluation. This paper proposes an innovative methodological approach to evaluate hazards by turning the qualitative judgments to quantitative, where sets of general and domain-specific criteria are used to judge the relative consequences of alternative hazards. The proposed methodology has the innovative feature of embodying techniques of fuzzy logic theory into the classical multicriteria decision analysis. The paper concludes by exploring the potentiality of the above methodology in providing a robust and flexible evaluation framework suitable to the characteristics of a hazard evaluation problem.

Assessing Uncertainty in Simulation Based Maritime Risk Assessment

Abstract

Recent work in the assessment of risk in maritime transportation systems has used simulation-based probabilistic risk assessment techniques. In the Prince William Sound and Washington State Ferries risk assessments, the studies’ recommendations were backed up by estimates of their impact made using such techniques and all recommendations were implemented. However, the level of uncertainty about these estimates was not available, leaving the decision-makers unsure whether the evidence was sufficient to assess specific risks and benefits. The first step towards assessing the impact of uncertainty in maritime risk assessments is to model the uncertainty in the simulation models used. In this paper, a study of the impact of proposed ferry service expansions in San Francisco Bay is used as a case study to demonstrate the use of Bayesian simulation techniques to propagate uncertainty throughout the analysis. The conclusions drawn in the original study are shown, in this case, to be robust to the inherent uncertainties. The main intellectual merit of this work is the development of Bayesian simulation technique to model uncertainty in the assessment of maritime risk. However, Bayesian simulations have only been implemented as theoretical demonstrations. Their use in a large, complex system may be considered state of the art in the field of computational sciences.

Keywords: Uncertainty Analysis, Bayesian Simulation, Maritime Risk Assessment.

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Jurnal Fuzzy

Safety Assessment of FPSO Turret-Mooring System Using Approximate Reasoning and Evidential Reasoning

Berikut ini jurnal tentang FPSO. Yang tertulis disini hanya abstraknya saja, jika anda ingin membaca lebih jauh silakan klik link berikut: Jurnal fuzzy

Abstract

Numerous Acts of Parliament and Statutory Instruments which apply to Floating Production, Storage and Offloading (FPSO) developments in the United Kingdom Continental Shelf (UKCS), covering a wide range of issues including health, technical safety, work place safety, lifting operations, environmental protection and pollution prevention and control, are described. A comprehensive study of system safety evaluation of a typical
turret-mooring system used on FPSOs is described in this paper. A safety assessment method suggested using approximate reasoning and evidential reasoning approaches is proposed in this study. Subjective safety modelling at the bottom level in a hierarchical framework is carried out using an approximate reasoning approach. The evidential reasoning method is used to combine or aggregate safety estimates at lower levels to produce the safety estimate at the system level. The four main sub-systems (Turret (T), Fluid Transfer System (FTS), Turret Transfer System (TTS) and Interfacing System (IS)) are thoroughly examined in order to perform a subjective safety assessment of the turret-mooring system.

Can Fuzzy Logic Bring Complex Problems into Focus? Modeling Imprecise Factors in Environmental Policy

In modeling complex environmental problems, we often fail to make precise statements about inputs and outcome. In this case the fuzzy logic method native to the human mind provides a useful way to get at these problems.

Fuzzy logic has become a common way of dealing with information in a number of fields, such as control theory, smart machines, investment analysis and so on. But the application of fuzzy sets can and has been extended to environmental science and policy. For anyone who has worked on health and environmental issues, it becomes immediately obvious that we deal constantly with fuzzy concepts—hazard, acceptable, safe, etc. Even concepts such as carcinogen and neurotoxin define fuzzy sets whose members are selected by experts who review and make judgments on conflicting toxicology or epidemiology. In spite of their relevance and early efforts to promote
their use in risk assessment2, fuzzy logic applications are still rare in risk assessment or other environmental assessments.

In this paper we consider whether and how fuzzy logic and fuzzy arithmetic apply to risk assessment and environmental policy. We use a case study assessment of water quality in the Ganga river of India to illustrate this evaluation. Our goal is to consider whether and how much this approach can be applied more broadly for environmental assessments.

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Jurnal fuzzy

A STRUCTURED APPROACH TO RISK ASSESSMENT USING FUZZY LOGIC

A STRUCTURED APPROACH TO RISK ASSESSMENT USING FUZZY LOGIC

When bivalent logic is applied, there are just two possible answers to a question, namely those of yes or no. However, in practice questions exist that can be answered only with difficulty or practically cannot be answered unequivocally using the bivalent logic. Fuzzy logic makes it possible to answer a question by making a choice from among an infinite number of possible answers. Whereas when using bivalent logic we assign 1 to a yes answer and 0 to a no answer, when using fuzzy logic, a reply can be expressed by an arbitrary number equal to........

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jurnal : A STRUCTURED APPROACH TO RISK ASSESSMENT USING FUZZY LOGIC

ELEMENTS AND METHODS FOR RISK ASSESSMENT OF AN ELECTRIC POWER TRANSMISSION SYSTEM

ELEMENTS AND METHODS FOR RISK ASSESSMENT OF AN ELECTRIC POWER TRANSMISSION SYSTEM

Abstract.
Elements and methods for risk assessment of an electric power transmission system in terms of their influence on the environment are analyzed in the paper. Kinds and effects of the influence of the system on the ecological, social and technical systems are pointed out. According to the analysis of the elements for the assessment of a transmission system influence on the environment, a suggestion regarding the activities for overall risk assessment is made. Accident and cumulative risk are examined; analytical, statistical and fuzzy risk assessment methods are analyzed.

Key Words: Transmission system, environment, risk assessment, methods for risk assessment


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Fuzzy Decision Support System Using Risk Analysis

Jurnal fuzzy tentang sistem pendukung pengambilan keputusan dengan menggunakan analisa resiko

Fuzzy Decision Support System Using Risk Analysis

Abstract
the paper presents a contribution to construction of tools for decision making support in organisational system for uncertainty aspect. develop theory of risk assessment is based on the adapted fuzzy analytic hierarchy process(AHP). in decision making under uncertainty and consecutive appearing risk is devided into identified categories and factors of uncertainty. the basic method used in the numerical part of the evaluation is two pass Fuzzy AHP (applied: first for the importance and second for the uncertainty of risk factors). the process is based on determination of relations between particular risk categories and factors.......
key words: uncertainty factors, risk, estimation, fuzzy AHP Method, Three-Steps Systematic Approach, Deciding

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AIRPORT RISK ASSESSMENT : EXAMPLE, MODEL AND MITIGATION - jurnal Fuzzy Logic

Jurnal Fuzzy Logic

AIRPORT RISK ASSESSMENT : EXAMPLE, MODEL AND MITIGATION

Sebanyak sembilan halaman. jurnal berkaitan dengan hazard yang mungkin terjadi di airport runaway dan operasionalnya, risk assessment terkait dengan peralatan yang digunakan serta mitigasinya.

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