APPLICATIONS OF FUZZY LOGIC IN THE DESIGN OF VEGETATED WATERWAYS UNDER UNCERTAINTY1

ABSTRACT: Two methods for analyzing uncertainty are described and compared in terms of their applicability for designing vegetated waterways. The first approach uses First and Second Order Analysis and the second employs Fuzzy Logic. The two methods were used to evaluate the uncertain parameters in the Manning formula, which is used for calculating the velocity of water flow in vegetated channels. Results indicate that both approaches can provide the designer with an indication of reliability of the estimates, a way of selecting a design option which meets a specified probability of success, as well as a means of comparing the relative importance of uncertainty in various input parameters. Also, the two methods have the common advantage of being simple and requiring less data about the uncertain parameters compared to the more comprehensive stochastic approaches. Although the Fuzzy Logic approach appears to provide a more conservative design because of its slightly higher variance, compared with the First and Second Order Analysis, both methods have proven to be reliable and suitable to deal with uncertainty.     

模糊聚类法在化学事故中未知化学品判断的应用研究

介绍一种基于微机的有毒有害物质判定方法。用模糊聚类分析法对已有化学品知识库分类。通过对化学品事故现场观察到的综合信息的核查和量化，根据一个判定准则和优化方案，找到未知化学品的归属，同时给出一个比较保守的判断结果，作为突发事故的急救处理和对环境危害的快速评估依据。     

安全程度的可能性分析方法

提出了安全程度的模糊风险度量方法。在模糊可能性理论基础上研究了非确定因素危险程度的量化表示方法。提出了模糊系统安全分析的逻辑模型。这一方法是与基于概率理论之上的方法完全不同的安全分析方法。给出了基于概率可能性和模糊可能性基础上的安全程度的含义和系统安全分析方法及适用条件     

Design for optimal quality by recycling returned products

For many manufacturers, the cost of replacing returned products may more than offset the cost of producing parts with a higher quality. This is especially true if good parts from returned products are used to remanufacture aftermarket products. Furthermore, such policy allows for satisfying a customer population with a variable expectation for acceptable quality. In this study, the total cost of supplying a given demand is derived as an analytical function of the targeted primary production rate and product quality when the demand is satisfied with a combination of primary and remanufactured products. The decision variables of this function consist of the primary production rate and the designed product and production quality. This cost is then minimised to determine the production rate and the optimum quality to target. A numerical example is provided and used to demonstrate the application of this function. This example also demonstrates the use of the proposed solution for optimising quality when there is a limit on primary production size. The example also demonstrates the use of the function for optimising service levels. The results show a close match between the theoretical functions developed in this study and those obtained from a Monte Carlo simulation model.     

RCNet: An optimisation software for the synthesis of resource conservation networks

RCNet is a spreadsheet-based software for the synthesis of resource conversation networks (RCNs) for planning the efficient use of material resources (e.g., water, utility gases, solvents) in industrial plants. The software is developed based on the well-established process integration tools, namely pinch analysis and mathematical programming techniques. In the first stage, pinch analysis is used to determine maximum resource conservation targets prior to detailed RCN design. In the second stage, mathematical optimisation is then used to determine the optimal flowrate allocation between process sources and sinks of the RCN, to achieve the performance targets. RCNet is applicable for various industrial applications. To date, no generic software has been developed to handle water minimisation, hydrogen recovery and property integration, which is the main subject of this work. In the developed software, same interface and platform can be used to solve abovementioned problems independently. For illustration, three literature examples on water minimisation, hydrogen recovery and property integration, as well as an industrial case study are solved using RCNet.     

Assessment of health-care waste disposal methods using a VIKOR-based fuzzy multi-criteria decision making method

Nowadays selection of the appropriate treatment method in health-care waste (HCW) management has become a challenge task for the municipal authorities especially in developing countries. Assessment of HCW disposal alternatives can be regarded as a complicated multi-criteria decision making (MCDM) problem which requires consideration of multiple alternative solutions and conflicting tangible and intangible criteria. The objective of this paper is to present a new MCDM technique based on fuzzy set theory and VIKOR method for evaluating HCW disposal methods. Linguistic variables are used by decision makers to assess the ratings and weights for the established criteria. The ordered weighted averaging (OWA) operator is utilized to aggregate individual opinions of decision makers into a group assessment. The computational procedure of the proposed framework is illustrated through a case study in Shanghai, one of the largest cities of China. The HCW treatment alternatives considered in this study include “incineration”, “steam sterilization”, “microwave” and “landfill”. The results obtained using the proposed approach are analyzed in a comparative way.     

A fuzzy DEMATEL method to evaluate critical operational hazards during gas freeing process in crude oil tankers

Gas freeing process in crude oil tanker ships is widely recognized one of the most hazardous aspects of shipboard operations. Although the process provides practical benefits to ship by removing the explosive or poisonous gases from the cargo tanks and raising the oxygen level up to 21 percent, the consequences of failure may cause serious damage to human health, marine environment and cargo. Therefore, the crew exercise utmost care and become aware of the potential hazards in gas freeing process. In this context, this paper provides a fuzzy DEMATEL (Decision Making Trial and Evaluation Laboratory) method to evaluate critical operational hazards in gas freeing process. While the DEMATEL method enables to identify and analyse the potential hazards of gas freeing process with respect to causal–effect relation diagram, fuzzy sets deal with the uncertainty in decision-making and human judgements through the DEMATEL. Thus, the hybrid approach provides smart solution for safety practitioners to prevent critical hazards in gas freeing process. The results of the research will contribute to maritime safety at sea and prevention of environment pollution as well as loss of life on-board crude oil tankers ships.     

Test case based risk predictions using artificial neural network

INTRODUCTION: The traditional fuzzy-rule-based risk assessment technique has been applied in many industries due to the capability of combining different parameters to obtain an overall risk. However, a drawback occurs as the technique is applied in circumstances where there are multiple parameters to be evaluated that are described by multiple linguistic terms. METHOD: In this study, a risk prediction model incorporating fuzzy set theory and Artificial Neural Network (ANN) capable of resolving the problem encountered is proposed. An algorithm capable of converting the risk-related parameters and the overall risk level from the fuzzy property to the crisp-valued attribute is also developed. Its application is demonstrated by a test case evaluating the navigational safety within port areas. RESULTS: It is concluded that a risk predicting ANN model is capable of generating reliable results as long as the training data takes into account any potential circumstance that may be met. IMPACT ON INDUSTRY: This paper provides safety assessment practitioners with a novel and flexible framework of modelling risks using a fuzzy-rule-base technique. It is especially applicable in circumstances where there are multiple parameters to be considered. The proposed framework also enables the port industry to manage navigational safety in a rational manner.     

Evaluating Environmental Sustainability: An Integration of Multiple-Criteria Decision-Making and Fuzzy Logic

While pursuing economic development, countries around the world have become aware of the importance of environmental sustainability; therefore, the evaluation of environmental sustainability has become a significant issue. Traditionally, multiple-criteria decision-making (MCDM) was widely used as a way of evaluating environmental sustainability, Recently, several researchers have attempted to implement this evaluation with fuzzy logic since they recognized the assessment of environmental sustainability as a subjective judgment Intuition. This paper outlines a new evaluation-framework of environmental sustainability, which integrates fuzzy logic into MCDM. This evaluation-framework consists of 36 structured and 5 unstructured decision-points, wherein MCDM is used to handle the former and fuzzy logic serves for the latter, With the integrated evaluation-framework, the evaluations of environmental sustainability in 146 countries are calculated, ranked and clustered, and the evaluation results are very helpful to these countries, as they identify their obstacles towards environmental sustainability.     

Sensitivity Analysis of Aggregated Indices for Integrated Assessment with a Case Study of the Mid-Atlantic Region

Environmental indicators are often aggregated into a single index for various purposes in environmental studies. Aggregated indices derived from the same data set can differ, usually because the aggregated indices' sensitivities are not thoroughly analyzed. Furthermore, if a sensitivity analysis is carried out, it is not presented in a transparent fashion to policy decision-makers. This paper presents a method of generating various aggregated environmental indices and analyzing their sensitivities via the use of the fuzzy set concept. Results show that several insights into the environmental conditions of the study area (e.g., the distribution of good or bad values of indicators at a watershed and or across the region) can be revealed in the sensitivity analysis of aggregated indices.