Osman Taylan

Construction projects selection and risk assessment by fuzzy AHP and fuzzy TOPSIS methodologies

Construction projects are initiated in dynamic environment which result in circumstances of high uncertainty and risks due to accumulation of many interrelated parameters. The purpose of this study is to use novel analytic tools to evaluate the construction projects and their overall risks under incomplete and uncertain situations. It was also aimed to place the risk in a proper category and predict the level of it in advance to develop strategies and counteract the high-risk factors. The study covers identifying the key risk criteria of construction projects at King Abdulaziz University (KAU), and assessing the criteria by the integrated hybrid methodologies. The proposed hybrid methodologies were initiated with a survey for data collection. The relative importance index (RII) method was applied to prioritize the project risks based on the data obtained. The construction projects were then categorized by fuzzy AHP and fuzzy TOPSIS methodologies. Fuzzy AHP (FAHP) was used to create favorable weights for fuzzy linguistic variable of construction projects overall risk. The fuzzy TOPSIS method is very suitable for solving group decision making problems under the fuzzy environment. It attempted to incorporate vital qualitative attributes in performance analysis of construction projects and transformed the qualitative data into equivalent quantitative measures. Thirty construction projects were studied with respect to five main criteria that are the time, cost, quality, safety and environment sustainability. The results showed that these novel methodologies are able to assess the overall risks of construction projects, select the project that has the lowest risk with the contribution of relative importance index. This approach will have potential applications in the future.

Determination of wax content in crude oil

ABSTRACT Wax deposition is one of the chronic problems in the petroleum industry. The various crude oils present in the world contain wax contents of up to 32.5%. Paraffin waxes consist of straight chain saturated hydrocarbons with carbons atoms ranging from C18 to C36. Paraffin wax consists mostly with normal paraffin content (80–90%), while, the rest consists of branched paraffins (iso-paraffins) and cycloparaffins. The sources of higher molecular weight waxes in oils have not yet been proven and are under exploration. Waxes may precipitate as the temperature decreases and a solid phase may arise due to their low solubility. For instance, paraffinic waxes can precipitate out when temperature decreases during oil production, transportation through pipelines, and oil storage. The process of solvent dewaxing is used to remove wax from either distillate or residual feedstocks at any stage in the refining process. The solvents used, methyl-ethyl ketone and toluene, can then be separated from dewaxed oil filtrate stream by membrane process and recycled back to be used again in solvent dewaxing process.

Biogas production from municipal sewage sludge (MSS)

ABSTRACT Biogas is produced by anaerobic (oxygen free) digestion of organic materials such as sewage sludge, animal waste, and municipal solid wastes (MSW). As sustainable clean energy carrier biogas is an important source of energy in heat and electricity generation, it is one of the most promising renewable energy sources in the world. Biogas is produced from the anaerobic digestion (AD) of organic matter, such as manure, MSW, sewage sludge, biodegradable wastes, and agricultural slurry, under anaerobic conditions with the help of microorganism. Biogas is composed of methane (55–75%), carbon dioxide (25–45%), nitrogen (0–5%), hydrogen (0–1%), hydrogen sulfide (0–1%), and oxygen (0–2%). The sewage sludge contains mainly proteins, sugars, detergents, phenols, and lipids. Sewage sludge also includes toxic and hazardous organic and inorganic pollutants sources. The digestion of municipal sewage sludge (MSS) occurs in three basic steps: acidogen, methanogens, and methanogens. During a 30-day digestion period, 80–85% of the biogas is produced in the first 15–18 days. Higher yields were observed within the temperature range of 30–60°C and pH range of 5.5–8.5. The MSS contains low nitrogen and has carbon-to-nitrogen (C/N) ratios of around 40–70. The optimal C/N ratio for the AD should be between 25 and 35. C/N ratio of sludge in small-scale sewage plants is often low, so nitrogen can be added in an inorganic form (ammonia or in organic form) such as livestock manure, urea, or food wastes. Potential production capacity of a biogas plant with a digestion chamber size of 500 m3 was estimated as 20–36 × 103 Nm3 biogas production per year.

Removing of resins from crude oils

ABSTRACT Crude oil contains four chemical group classes, namely saturates, aromatics, resins, and asphaltenes (SARA fractions). Resins fraction of crude oil comprises polar molecules often containing heteroatoms such as nitrogen, oxygen, or sulfur. Resin is a heavier fraction than aromatics and saturates. Resins are composed of fused aromatic rings with branched paraffin and polar compounds. The resin fraction is soluble in light alkanes such as pentane and heptane, but insoluble in liquid propane. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution. The resins often coprecipitate with the asphaltenes in controlled propane deasphalting procedures. The composition of the resins can vary considerably and is dependent on the kind of precipitating liquid and on the temperature of the liquid system. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution.

Recovery of Gasoline-Range Hydrocarbons From Petroleum Basic Plastic Wastes

A solid waste management system based on the 3R principle: reduce, reuse, and recycle. There are two major recycling methods for conversion of plastic wastes to synthetic fuels: (a) pyrolysis in absence and presence of catalyst and (b) thermal and/or catalytic cracking. Pyrolysis is a complex series of chemical and thermal reactions to decompose or depolymerize organic material under oxygen-free conditions. The most affecting variables of plastic pyrolysis are catalyst type and shape, temperature, and residence time. Certain types of waste plastics such as polystyrene (PS), polyethylene (PE), and polypropylene (PP) are generally used in pyrolysis. The plastic wastes can be pyrolyzed into liquid, gas, and solid residue products. The pyrolysis of plastic wastes produces a whole spectrum of hydrocarbons including paraffins, olefins, naphthalenes, and aromatics. The total yields of paraffins and olefins of PE and PP wastes obtained by pyrolysis were higher than that of PS. The oil obtained from plastic pyrolysis could improve performance by modifying engine. The addition of catalyst in the pyrolysis can be a more efficient method to produce high valuable products with mainly gasoline-range hydrocarbons. The catalytic decomposition was produced much more light hydrocarbons than that of thermal decomposition. Especially, ZSM-5 with a smaller pore size, rather than that of zeolite Y was more cracked into light hydrocarbons such as C6-C12 hydrocarbons and gas products.

Fuzzy control charts for process quality improvement and product assessment in tip shear carpet industry

Purpose – The purpose of this paper is to demonstrate the use of artificial intelligence methods in quality control and improvement. The paper introduces a systematic approach for the design of fuzzy control charts of tip shear carpets.Design/methodology/approach – There are certain steps for designing fuzzy control charts. All input, state and output variables of the carpet plant and partition of the universe of discourse were first determined. The interval spanned by each variable and the number of fuzzy subsets each assigned with a linguistic label were identified. Then, the adaptive capability of neural network was used to determine the membership functions for each fuzzy subset. The fuzzy relationship functions between the inputs and outputs were assigned to form the fuzzy rule base (controller) in order to normalize the variables and certain intervals. Fuzzification of input parameters and max‐min composition of rules for inferring crisp outputs was the next step. The aggregation of fuzzified output...

A multi-criteria decision-making approach that combines fuzzy topsis and DEA methodologies

Employee selection is a multi-criteria decision-making (MCDM) problem for selecting suitable applicants from a ready pool. The selection aims to make use of their knowledge, relevant skills, and other characteristics to perform a specific job. The aim of this study is to develop a systematic approach for selecting the best candidates among the air traffic controllers (ATCs) for aviation in Saudi Arabia. Three integrated methods were employed for decision-making in this study. First, a fuzzy decision tree was applied to determine the criteria weights, then the fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to rank the attributes. In the last step, the Data Envelopment Analysis (DEA) was used to transform the qualitative variables into quantitative equivalences. A survey was conducted by national and international decision- makers to elicit the necessary information on the criteria and sub-criteria of the air traffic control system. The decision problem was formulated by employing five criteria and ten applicants. The relationship between the fuzzy TOPSIS and fuzzy-weighted average was very positive for decision-making. The outcomes of the fuzzy TOPSIS and DEA encouraged the development of a decision support system for the selection of ATCs.

An energy efficiency analysis of an industrial reheating furnace and an implementation of efficiency enhancements methods

Rapid consumption of energy resources, increasing energy needs, the competitive conditions in the industry and environmental concerns, all of those call for efficient use of energy resources. In this context, energy efficiency studies were carried out in a rolling mill of a reheating furnace of an integrated industrial enterprise. In studies, some important efficiency measurements were conducted, mass and energy balances were established by using the results of these measurements and the operating data of the plant along with energy saving opportunities, with the specified amounts and repayment periods were determined. Energy conservation studies that can be realized in the reheating furnace were considered including operation of the reheating furnace with the pertinent excess air coefficient, compensation of the air leakage losses in the recuperator and establishment of the economizer in the furnace. As a result of these investigations some saving opportunities were determined and a new recuperator, economizer and gas analyzer were installed in the reheating furnace leading in total of 2,913,924 kcal/h of energy savings. After the implementation of energy saving measures, reheating furnace efficiency was increased from 61.83% to 69.43%.

Selection of compressors for petrochemical industry in terms of reliability, energy consumption and maintenance costs examining different scenarios

In this study, based on some important criteria, qualitative and quantitative evaluations were presented for the selection of compressors used in compressed air systems, in a petrochemical industry. Four different scenarios were investigated according to the main criteria considered for the selection of the compressors such as reliability, energy efficiency, investment, and maintenance costs. The types of compressor and their capacities were analyzed and compared. In Scenario I, the currently active electrically driven compressors were considered as backup compressors, instead of them, a new unit turbo compressor and two units of VSD screw compressors were purchased as active compressors. In this scenario, the initial investment cost is low and standby steam consumption is reduced due to the fact that the backup compressors are electrically driven. In Scenario II all active and backup compressors are replaced by a new one, which is proposed to be electrically driven. In this scenario, the initial investment cost is high, but energy consumption is very low. In Scenario III, all active compressors are planned to be replaced by new backup steam-driven compressors. In this scenario, although the initial investment costs and energy consumption are high, the reliability of this scenario is higher than the reliability of Scenarios I and II. In Scenario IV, all compressors are projected to be replaced by new and equivalent compressors. In this scenario, the initial investment cost and energy consumption are high, but the reliability of this scenario is the highest comparing all other scenarios. The aim of this study is to contribute the studies on the selection of compressors by considering some important parameters as their types and capacities, in particular, for industrial enterprises that have risk of explosion like in the petrochemical industry.

Forecasting and analysis of energy consumption for transportation in the Kingdom of Saudi Arabia

ABSTRACT The objectives of this study are (a) to develop a comprehensive understanding of the transportation sector, including energy consumption by all subsectors and (b) to study the key factors that drive the fuel and energy demand. The study will focus on the transportation sector as a key component of the economy, and the engine for economic development. This sector is heavily energy intensive and largely relies on petroleum fuel products including energy consumption by all subsectors, namely automotive, air, rail-road, pipeline, and maritime transportation. Energy and transportation industries are becoming a significant factor affecting social economy. The future development of the energy and transportation industries will be confronted with this change as well.