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  • Author: Muhammad Ahmad x
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Abstract

The rising market for substitute materials in high voltage insulation components is stimulated largely by the need to reduce overall costs. In this respect, polymer insulators offer significant advantages over old traditional materials. In the present research, efforts have been made to quantify the effect of silica (having different particle size nano, micro and hybrid) loading on the mechanical and thermal behaviors of Ethylene-Propylene-Diene Monomer (EPDM) based high voltage electrical insulations. The fabricated composites were subjected to mechanical, thermal and electrical properties measurements. The results of dielectric strength, surface and volume resistivities showed that all composites had insulator properties, while their mechanical and thermal properties improved considerably. EPDM was compounded with different types of silica in a two roll mill using sulphur cure system. The outcome achieved from the comparative study revealed that the EPDM nanocomposites had enhanced mechanical, thermal and electrical properties even at 5 % loadings.

Abstract

In this paper, we propose and analyse an iterative algorithm for the approximation of a common solution for a finite family of k-strict pseudocontractions and two finite families of generalized equilibrium problems in the setting of Hilbert spaces. Strong convergence results of the proposed iterative algorithm together with some applications to solve the variational inequality problems are established in such setting. Our results generalize and improve various existing results in the current literature.

Abstract

This paper aims to investigate the relationship between fabric weave structure and its comfort properties. The two basic weave structures and four derivatives for each selected weave structure were studied. Comfort properties, porosity, air permeability and thermal resistance of all the fabric samples were determined. In our research the 1/1 plain weave structure showed the highest thermal resistance making it suitable for cold climatic conditions. The 2/2 matt weave depicted the lowest thermal resistance which makes it appropriate for hot climatic conditions.

Abstract

Use of bran oil in various edible and nonedible industries is very common. In this research work, efficient and optimized methodology for the recovery of rice bran oil has been investigated. The present statistical study includes parametric optimization, based on experimental results of rice bran oil extraction. In this study, three solvents, acetone, ethanol and solvent mixture (SM) [acetone: ethanol (1:1 v/v)] were employed in extraction investigations. Response surface methodology (RSM), an optimization technique, was exploited for this purpose. A five level central composite design (CCD) consisting four operating parameter, like temperature, stirring rate, solvent-bran ratio and contact time were examined to optimize rice bran oil extraction. Experimental results showed that oil recovery can be enhanced from 71% to 82% when temperature, solvent-bran ratio, stirring rate and contact time were kept at 55°C, 6:1, 180 rpm and 45 minutes, respectively while fixing the pH of the mixture at 7.1.

Abstract

This study aimed to investigate the amount and type of teacher-talk, frequently asked questions and feedback provided by the teacher on learners’ performance in a language classroom. For this purpose, a lecture was recorded from a secondary level English language classroom of a public sector school and interpreted in the light of teacher-student interaction and classroom management model by David Nunan. Results revealed that the maximum amount of time (i.e. 80.1%) was consumed by the teacher which was appropriate. However, certain deviations from classroom management principles were also observed regarding frequently asked questions (i.e. 50% of the total questions were elicitation questions) and the feedback (it was ‘romantic’ in nature). Moreover, wait-time was sufficient but it was of no use to the learners. The study concluded that classroom practices did not conform to the principles therefore, it proposed to ask questions and provide feedback appropriately.

Abstract

Advertising and Analytics (A&A) companies have started collaborating more closely with one another due to the shift in the online advertising industry towards Real Time Bidding (RTB). One natural way to understand how user tracking data moves through this interconnected advertising ecosystem is by modeling it as a graph. In this paper, we introduce a novel graph representation, called an Inclusion graph, to model the impact of RTB on the diffusion of user tracking data in the advertising ecosystem. Through simulations on the Inclusion graph, we provide upper and lower estimates on the tracking information observed by A&A companies. We find that 52 A&A companies observe at least 91% of an average user’s browsing history under reasonable assumptions about information sharing within RTB auctions. We also evaluate the effectiveness of blocking strategies (e.g., AdBlock Plus), and find that major A&A companies still observe 40–90% of user impressions, depending on the blocking strategy.

Abstract

A process model for turbulent pressurized circulating fluidized-bed coal gasifier is created using ASPEN PLUS software. Both hydrodynamic and reaction kinetics parameter are taken into account, whose expressions for fluidized bed are adopted from the literature. Various reactor models available in ASPEN PLUS with calculator as External Block are nested to solve hydrodynamics and kinetics. Multiple operational parameters for a pilot-plant circulating fluidized-bed coal gasifier are used to demonstrate the effects on coal gasification characteristics. This paper presents detailed information regarding the simulation model, including robust analysis of the effect of stoichiometric ratio, steam to coal ratio, gasification temperature and gasification agent temperature. It is observed that, with the increase in the flow rate of air, the components hydrogen, carbon monoxide, carbon dioxide and methane reduce, which causes the Lower Heating Value (LHV) of synthesis gas (Syn. Gas) to decrease by about 29.3%, while increment in the steam flow rate shows a minute increase in heating value of only 0.8%. Stoichiometric ratio has a direct relationship to carbon conversion efficiency and carbon dioxide production. Increasing the steam to coal ratio boosts the production of hydrogen and carbon monoxide, and causes a drop in both carbon dioxide concentration and the conversion efficiency of carbon. High gasifying agent temperature is desired because of high concentration of CO and H2, increasing carbon conversion and LHV. A high gasifying agent temperature is the major factor that affects the coal gasification to enhance H2 and CO production rapidly along with other gasification characteristics.

Abstract

A common problem faced in fabric manufacturing is the production of inconsistent fabric width on shuttleless looms in spite of the same fabric specifications. Weft-wise crimp controls the fabric width and it depends on a number of factors, including warp tension, temple type, fabric take-up pressing tension and loom working width. The aim of this study is to investigate the effect of these parameters on the fabric width produced. Taguchi’s orthogonal design was used to optimise the weaving parameters for obtaining controlled fabric width. On the basis of signal to noise ratios, it could be concluded that controlled fabric width could be produced using medium temple type and intense take-up pressing tension at relatively lower warp tension and smaller loom working width. The analysis of variance revealed that temple needle size was the most significant factor affecting the fabric width, followed by loom working width and warp tension, whereas take-up pressing tension was least significant of all the factors investigated in the study.

Abstract

Desulfurization of Pakistani coal has been carried out through alkaline leaching. During present experimental investigation, the effect of operating parameters like alkali concentration, time, temperature and particle size has also been analyzed, graphically represented and critically discussed. Parametric optimization of leaching process has been carried out by using response surface methodology (RSM) based on central composite design (CCD). The analysis of variance (ANOVA) was performed in order to assess the highest level interactions of variables and three way interactions were observed signifi cant. Further, the optimum value of total sulfur removal was observed as 53% when the operatic conditions fi xed at 10% W/V, 60 min, 80oC and 140 mesh for alkaline concentration, leaching time, temperature and particle size, respectively.

Abstract

The present invention was undertaken to study and determine the effect of potassium metabisulphite (6%) and potassium sorbate (350 ppm) treatments on the nutritional quality of osmotically-dehydrated, infrared- and microwave-blanched dried mango slices (local cultivars “Chaunsa” and “Fajri”) stored for the period of 6 months under ambient conditions. The studied parameters included physical characteristics such as water activity, non-enzymatic browning, and color values, chemical parameters such as moisture, ash, fiber, acidity and content of proteins, sugars, vitamin C, total carotenoids, and sensory attributes such as appearance, flavor and texture. Vitamin C content in osmotically-dried mango slices was higher than that of IR and MW blanched dried mango slices but the content of vitamin C of both cultivars was lower than of the fresh mango samples (Chaunsa: 135 mg/100 g, Fajri: 94 mg/100 g). Significant loss was noticed in total carotenoids content of both the cultivars with passage of time because of their susceptibility to oxidative loss caused by dry heat. No growth of yeast and mold was detected in potassium sorbate-treated dried mango slices due to their preservative effect. From the point of view of the composition and sensory quality, dried mango slices of both the cultivars have excellent nutritional qualities.