A fuzzy logic approach for dealing with qualitative quality characteristics of a process

Dealing with qualitative information is quite common in real life problems. So far research focused on developing process adjustment models only for quantitative data. This paper presents a process adjustment approach of a deteriorating process in which quality characteristics are expressed in qualitative form. This approach jointly determines the initial setting of process mean and production run. A fuzzy logic is adopted to implement the process adjustment approach. The features of this approach are lack of mathematical complexity and ability to deal with qualitative data. Detailed implementation of the fuzzy process adjustment model is also given in this paper.     

Hierarchical approach for fatigue cracking performance evaluation in asphalt pavements

In this paper, a hierarchical approach is proposed for the evaluation of fatigue cracking in asphalt concrete pavements considering three different levels of complexities in the representation of the material behaviour, design parameters characterization and the determination of the pavement response as well as damage computation. Based on the developed hierarchical approach, three damage computation levels are identified and proposed. The levels of fatigue damage analysis provides pavement engineers a variety of tools that can be used for pavement analysis depending on the availability of data, required level of prediction accuracy and computational power at their disposal. The hierarchical approach also provides a systematic approach for the understanding of the fundamental mechanisms of pavement deterioration, the elimination of the empiricism associated with pavement design today and the transition towards the use of sound principles of mechanics in pavement analysis and design.     

Physical Properties of Aqueous N-Methyl Pyrrolidone at Different Temperatures

Many physical properties of aqueous N-Methyl pyrrolidone mixtures were determined for molar fraction X_NMP = 0.02, 0.05, 0.125, 0.32, 0.37 at different temperatures ranging from 15-65°C. From the result we noticed that the viscosity coefficient was increased with increasing the molar fraction X_NMP and reached a maximum value at X_NMP = 0.25-0.37, and decreased with temperature. We observed the same relationship of the thermodynamic properties for the mixture at different temperatures and for excess activation function was positive. They reached maximum value at the X_NMP = 0.25-0.37. The same relationship was observed for excess dielectric constant. The results were explained according to hydrogen bonding effects and dipole-dipole interactions. This binding is stronger than binding between water molecules which may be let to form a complex at the molal fraction ratio 2:1 of water-NMP solution. We noticed that an increase in temperature may be let to tighten the interaction between water and NMP.     

The Improvement of the Quality of Raffinate Obtained from Solvent Extraction of Lubricating Oils

Abstract

Vacuum distillates of an Egyptian crude oil were subjected to solvent extraction process applying N-methyl-2-pyrrolidone (NMP) and furfural as dearomatization solvents. The study shows that the extraction solvent together with the temperature and solvent-to-oil ratio have a significant effect on the yield and quality of produced lubricating oils. The optimum temperature for extracting light waxy distillates with NMP is 55°C at the solvent-to-feed ratio 2:1. These conditions are appropriate to remove the major portion of aromatics from the raffinate. The apparent activation energy (Ea), enthalpy (ΔH*), entropy (ΔS*), and free energy of activation (ΔG*) were calculated for the solvent dearomatization process.     

The Oxidation Stability of Lubricating Oil

Abstract

Lubricating oil is generated throughout the year and collected in central locations in many communities. The studied lube oil has a boiling range of 280°C–400°C, and its physical properties were determined according to standard test methods in ASTM and International Petroleum. Solvent extraction by furfural was carried out using different feed ratios. The best ratio was 1:4 (sample:furfural). The oil was separated into its components using liquid column chromatography. It was found that the aromatic contents decreased. The structure group analysis was determined by infrared spectroscopy and refractive index-density-molecular weight methods. The oxidation stability was carried out according to ASTM method D-48 using an inhibitor. The inhibitor used was a nonionic surfactant, alkanolamide. The results showed that the oxidation stability improved using the inhibitor.     

Hydrogen production by catalytic methane decomposition over Ni,Co, and Ni-Co/Al2O3 catalyst

Hydrogen is a chief source of energy. Catalytic decomposition produces hydrogen and carbon. In this work, x%M/Al₂O₃ (where M is Ni, Co and combined Ni-Co, and x is 10%, 15%, and 30%) has been successfully employed as a catalyst. The effect of activation temperature and active metal type and loading on catalyst perfomance was investigated. The catalysts were characterized with BET, XRD, TPO, TPR, TEM, XPS, and Raman. The results displayed that the 30%Co/Al₂O₃ catalyst activated at 500°C provided the greatest catalytic performance toward methane conversion. 30%Co/Al₂O₃ catalyst activated at 500°C formed amorphous carbon.     

Improving the dyeing properties of textiles via utilization of redox systems. I. Dyeing of wool and wool/polyacrylic blend fabrics with acid dye

Dyeing of wool and wool/polyacrylic fabrics with an acid dye, namely, Kiton Scarlet 4 R, was carried out in absence or presence of different redox systems. The latter were based on sodium, potassium, or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, sodium thiosulphate, potassium pyrosulphite or thiourea as reductant. Regardless of the redox system used, the colour strength was far greater in presence than in absence of the redox system. Except in case of potassium periodate/glucose redox system, increasing the oxidant concentration up to 0.03 mol/l caused significant enhancement in colour strength. The same was observed upon increasing the temperature from 30 to 60°C as well as the time from 10 to 40 minutes. It is postulated that presence of the redox system alters the mode of dye attachment to the substrate. Association of the dye with the substrate, wool in particular, seems to involve covalent bonding beside the usual salt-linkage. Hence the approach presented is advantageous in producing dyeings with much higher colour strength and dye fixation at relatively low temperature.     

Improving the dyeing properties of textiles via utilization of redox systems. II. Dyeing of nylon-6 with acid dye

Redox systems based on potassium, sodium or ammonium peroxodisulphate or potassium periodate as oxidant and glucose, thiourea, sodium thiosulphate or potassium pyrosulphite as reductant were incorporated in the dyeing bath of nylon-6 under a variety of conditions. An acid dye, namely Kiton Scarlet 4 R was used. The colour strength and dye fixation enhanced outstandingly in presence of the redox system, depending upon kind and concentration of the redox components. Raising the dyeing temperature from 30 to 60°C caused significant improvement in colour strength. The same holds true for duration of dyeing up to 60 min. Beside association of the dye with nylon-6 by salt-like bond, a free radical mechanism was suggested.     

Theoretical investigation into instability of a refrigeration system with an evaporator controlled by a thermostatic expansion valve

A theoretical model is developed and solved to investigate the instability of a refrigeration system with an evaporator controlled by a thermostatic expansion valve. An evaporator time constant is used to account for the delay of the liquid refrigerant distribution along the two phase region. Results show that there is an evaporator critical time constant, below which the system operates in a stable manner. This critical time constant is found to decrease with decreasing the partial load and to increase with increasing the contact thermal resistance and the two-phase region heat transfer coefficient. The bulb size is also found to have a great effect on the stability.