Application of Grey-Taguchi method for simultaneous optimization of multiple quality characteristics in lead-slag radiation shielding concrete

Utilization of wastes and by-products as concrete aggregate has received increasing attention in the last few years. Lead slag extracted from recycling of the spent batteries, is one of these waste materials which have high potential and can be utilized as substitute of raw materials in construction of radiation shielding concrete. For utilization of lead slag as Radiation-shielding concrete aggregate, we should consider different criteria. Therefore, It is necessary to find an optimal mixture to produce Lead Slag radiation shielding concrete (LSRSC) with desired quality characteristics. In the present work, Taguchi method in combination with grey relational analysis is applied to find the optimal mixture of LSRSC with multiple responses. In the application of this method, water/cement ratio, cement quantity, volume ratio of lead slag aggregate and Silica fume were selected as control factors with responses of slump, Unit weight, compressive strength and gamma attenuation coefficient to assess the optimal mixture of LSRSC. Results demonstrated that the optimal mixture of LSRSC has a water/cement ratio of 0.42, cement quantity of 390 kg, a volume fraction of lead slag aggregate of 60% and silica fume-cement ratio of 0.15

Treatability studies of hospital wastewaters with AOPs by Taguchi’s experimental design

In this study, it was studied various advanced oxidation treatment processes; Fenton, UV/H2O2, UV/O-3/H2O2 for treatability of hospital wastewaters containing antibiotics (cephalosporines). Taguchi's L25 orthogonal array design was applied to design of advanced oxidation processes, for simplification of the analysis and calculations. 95,7%, 90,65%, 91,8% COD and 55,86%, 60,83%, 70,8% TOC removal efficiencies were obtained under the best operation conditions for UV/H2O2, UV/O-3/H2O2 and Fenton processes, respectively. According to the ANOVA results, pH was of great importance in COD removal for Fenton. For the UV/H2O2 processes, H2O2 has significance in COD and TOC removals. As for the O-3/UV/H2O2 processes, O-3/UV reaction time was found as an important parameter effecting the removal rates. Also, cephalosporine antibiotic active compounds (cefradine and cefaclor) were degraded completely within minutes for all of the processes. Taguchi's Method was found useful for the environmental applications and simplifications of advanced oxidation processes for treatment of hospital wastewaters and calculations

Fuzzy TOPSIS for Multiresponse Quality Problems in Wafer Fabrication Processes

The quality characteristics in the wafer fabrication process are diverse, variable, and fuzzy in nature. How to effectively deal with multiresponse quality problems in the wafer fabrication process is a challenging task. In this study, the fuzzy technique for order preference by similarity to an ideal solution (TOPSIS), one of the fuzzy multiattribute decision-analysis (MADA) methods, is proposed to investigate the fuzzy multiresponse quality problem in integrated-circuit (IC) wafer fabrication process. The fuzzy TOPSIS is one of the effective fuzzy MADA methods for dealing with decision-making problems under uncertain environments. First, a fuzzy TOPSIS methodology is developed by considering the ambiguity between quality characteristics. Then, a detailed procedure for the developed fuzzy TOPSIS approach is presented to show how the fuzzy wafer fabrication quality problems can be solved. Real-world data is collected from an IC semiconductor company and the developed fuzzy TOPSIS approach is applied to find an optimal combination of parameters. Results of this study show that the developed approach provides a satisfactory solution to the wafer fabrication multiresponse problem. This developed approach can be also applied to other industries for investigating multiple quality characteristics problems

Using a hybrid decision-making model to evaluate the sustainable development performance of high-tech listed companies

In this study, we use a triple bottom-line concept including economic, social and environmental performance as the sustainable development performance evaluation categories for companies. Moreover, an integrated model based on grey relational analysis, decision-making trial and evaluation laboratory, analytic network process and the technique for order preference by similarity to ideal solution is proposed for solving a corporate sustainability performance evaluation and ranking problem. In order to verify the proposed model, we adopt 34 high-tech listed companies in Taiwan as the research object to measure companies’ sustainable development performance and ranking in 2013. The results can be used as an important basis for management decision-making, and can also serve as reference for banks and investors when developing investment strategy

A Case Study to Solve Multi-Response Optimization Problem

In machining operations, achieving desired surface quality features of the machined product, is really a challenging job. Because, these quality features are highly correlated and are expected to be influenced directly or indirectly by the direct effect of process parameters or their interactive effects (i.e. on process environment). However, the extents of significant influence of the process parameters are different for different responses. Therefore, optimization of surface roughness is a multi-factor, multi-objective optimization problem. Therefore, to solve such a multi-objective optimization problem, it is felt necessary to identify the optimal parametric combination, following which all objectives could be optimized simultaneously. In this context, it is essential to convert all the objective functions into an equivalent single objective function or overall representative function to meet desired multi-quality features of the machined surface. The required multi-quality features may or may not be conflicting in nature. The representative single objective function, thus calculated, would be optimized finally. In the present work, Design of Experiment (DOE) with Taguchi L9 Orthogonal Array (OA) has been explored to produce 9 specimens on copper bard by straight turning operation. Collected data related to surface roughness have been utilized for optimization. Principal Component Analysis (PCA) has been applied to eliminate correlation among the responses and to evaluate independent or uncorrelated quality indices called principal components. Based on quality loss of individual principal components with respect to the ideal condition, CQL (COMBINED QUALITY LOSS) has been calculated to serve as the single objective function for optimization. Finally, Taguchi method has been adopted for searching optimal process condition to yield desired surface quality. Result of the aforesaid optimization procedure has been verified through confirmatory test. The study illustrates the detailed methodology of PCA based Taguchi method and its effectiveness for multi-response surface quality optimization in turning operatio

Using a decision-making process to evaluate efficiency and operating performance for listed semiconductor companies

Today’s high-tech industries face increasing competition and challenges. Thus, for hightech companies, making effective use of resources to enhance business performance and maintain the competitive advantage in the market has become increasingly important. Therefore, this study aimed to design a decision-making model for evaluating the efficiency and operating performance of Taiwan’s listed semiconductor companies in 2010 to provide a basis for improving business performance. In view of this, this study combines data envelopment analysis (DEA) and improved grey relational analysis (IGRA) as efficiency tools to measure relative efficiencies; the semiconductor companies are divided into two groups, efficient and inefficient. We then integrate the multiple criteria decision making (MCDM) method (e.g. VlseKriterijumska Optimizacija I Kompromisno Resenje, VIKOR), IGRA and the entropy weight method to evaluate the operating performance of the efficient and inefficient groups, respectively. Establishing a reasonable, objective and valid evaluation model to measure semiconductor companies’ operating efficiency can provide company managers, investors and policy makers with a reference for performance evaluation. First published online: 20 Jun 201

Rice husk : carbon dioxide reducer

Carbon dioxide can bring a major effect to the environment and lead us to the global warming and Green House effect. Besides that, it been listed as the major waste in the world that cannot easily be disposed. Due to these problems, many scientists recently investigate about how to overcome this issue. One of the uncostly and easy ways is using rice husk. It has been known that rice husk has the same characteristic with activated carbon which can adsorb carbon dioxide. This rice husk adsorbs carbon dioxide by trapping it into their pores. The main objective of this experiment is to study the tendency of rice husk as activated carbon to adsorb carbon dioxide. To generate the activated carbon behaviour, rice husk must be reacted with potassium hydroxide solution (KOH). The mixture of rice husk with Potassium hydroxide solution is dry by using oven. The dried rice husk is put into the Fourier-transformer Infrared (FTIR) to obtain the exact result to determine the compound that has the activated carbon behaviour. The range of the test is between 4000 to 650. The Fourier-transformer Infrared (FTIR) shows that activated carbon compound that has the least amount of peak is the best because it represents least amount of organic compound in that rice husk. So that the tendency to adsorb carbon dioxide is high

Experimental Studies on Machinability of Inconel Super Alloy during Electro-Discharge Machining: Emphasis on Surface Integrity and Metallurgical Characteristics of the EDMed Work Surface

Inconel alloys are Nickel-Chromium based high temperature super alloys widely applied in aerospace, marine, nuclear power generation; chemical, petrochemical and process industries. Execution of traditional machining operations on Inconel super alloy is quite difficult due to its very low thermal conductivity which increases thermal effects during machining operations. Inconel often exhibits strong work hardening behavior, high adhesion characteristics onto the tool face, and thereby alters cutting process parameters to a remarkable extent. Additionally, Inconel may contain hard abrasive particles and carbides that create excessive tool wear; and, hence, surface integrity of the end product appears disappointing. The extent of tool life is substantially reduced. Thus, Inconel super alloys are included in the category of ‘difficult-to-cut’ materials. In view of the difficulties faced during conventional machining, non-traditional machining routes like Electro-Discharge Machining (EDM), Wire Electro-Discharge Machining (WEDM), micro-machining (micro-electro-discharge drilling) etc. are being attempted for processing of Inconel in order to achieve desired contour and intricate geometry of the end product with reasonably good dimensional accuracy. However, low material removal rate and inferior surface integrity seem to be a challenge. In this context, the present dissertation has aimed at investigating machining and machinability aspects of Inconel super alloys (different grades) during electro-discharge machining. Effects of process control parameters (viz. peak discharge current, pulse-on time, gap voltage, duty factor, and flushing pressure) on influencing EDM performance in terms of Material Removal Rate (MRR), Electrode Wear Rate (EWR) and Surface Roughness (SR) of the EDMed Inconel specimens have been examined. Morphology along with topographical features of the EDMed Inconel work surface have been studied in view of severity of surface cracking and extent of white layer depth. Additionally, X-Ray Diffraction (XRD) analysis has been carried out to study metallurgical characteristics of the EDMed work surface of Inconel specimens (viz. phases present and precipitates, extent of grain refinement, crystallite size, and dislocation density etc.) in comparison with that of ‘as received’ parent material. Results, obtained thereof, have been interpreted with relevance to Energy Dispersive X-ray Spectroscopy (EDS) analysis, residual stress and micro-indentation hardness test data. Effort has been made to determine the most appropriate EDM parameters setting to optimize MRR, EWR, along with Ra (roughness average), relative Surface Crack Density (SCD), as well as relative White Layer Thickness (WLT) observed onto the EDMed work surface of Inconel specimens. Moreover, an attempt has been made to examine the ease of electro-discharge machining on Inconel work materials using Deep Cryogenically Treated (DCT) tool/workpiece. A unified attempt has also made to compare surface integrity and metallurgical characteristics of the EDMed Inconel work surface as compared to the EDMed A2 tool steel (SAE 304SS) as well as EDMed Titanium alloy (Ti-6Al-4V)