Sharif Digital Repository

Performance evaluation of drilling fluids is essential for a successful drilling project, as they not only remove drill cuttings but also prevent undesired penetration or outflow of formation fluids by sealing off wellbore walls. However, concerns have been raised about the use of chemical additives in drilling fluids due to their toxicity and non-biodegradability. To this end, agricultural waste materials are recognized as a promising alternative as they are cost-effective, environmentally sustainable, and can be used as a substitute for lost circulation materials. Rice husk ash (RHA) has become popular as an additive due to its renewable characteristics, including its large surface area,... 

Metamaterials are manmade structures that have attained considerable attention over the past 2 decades in the modern fields like cloaking, sensing, and imaging owing to their ability to harness electromagnetic fields. In this regard, we have inspected the dielectric properties of the hyperbolic metamaterials (HMM) made of metallic nanorods and dielectric medium at the infrared wavelength regime. The periodically arranged subwavelength-sized metallic nanorods embedded in the silicon dioxide (SiO 2) substrate glass. The spacing between two adjacent nanorods is of subwavelength in size. Furthermore, effective permittivity of the metamaterial has been analyzed by employing the Maxwell Garnett... 

Nanofluids play an important role in order to augment of the heat transfer characteristics in many energy systems. As compared to usual fluids, nanofluids comprise better physical strength and thermal conductivity. Our aim in studying this work is to numerically interpret the flow and heat transfer features of copper oxide (CuO) nanoparticles in the coexistence of thermal radiation and inclined magnetic fields. The model equations are first simplified by the similarity transformations and then finite difference discretization is used to apply the numerical technique known as the successive over-relaxation method. We have mainly examined that how much the thermal radiation and inclined... 

Food science researchers are concerned about global food wastage due to decreased shelf life. It has been shown that using approaches based on nanotechnology, including metal-based nanoparticles (NPs), can alleviate the issues with decreased shelf life and environmental problems. Gold nanoparticles (AuNPs) and their synthesis have seen notable advancements in the last several decades. AuNPs are now utilised more often in industrial and medicinal settings. AuNPs are being employed in the nanopackaging industry as a recently adopted technique because of their medicinal and antibacterial properties and their inert and hypoallergenic nature. When employed in the food industry, AuNPs have... 

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material’s heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly... 

Mango fruit borer (MFB) is a significant pest that damages mango fruits and leaves. This study explores farmers’ perceptions of the mango fruit borer and evaluates management practices. Survey findings indicated that 48% of mango growers believed MFB attacks occur during April-May, while 30% identified May-June as the peak season. Additionally, 84% of mango growers believed MFB affects fruits, while only 2% think it also targeted leaves. Most mango growers (78%) preferred chemical methods to manage MFB, with 40% using bifenthrin, 28% using emamectin benzoate, and only 8% applying imidacloprid. Experiments evaluating MFB’s preference for different mango varieties revealed that nearly all... 

Coccidiosis is a significant disease of poultry and is usually treated using various synthetic anticoccidial drugs. However, the effectiveness of this approach has been compromised due to drug resistance. Medicinal plants are being considered as potential alternatives to these drugs. As part of ongoing research, an investigation was conducted to assess the anticoccidial potential of Linum usitatissimum seed extract (LUE) and its impact on hematological parameters in broiler chickens with experimental coccidiosis. A total of 108 broiler chicks were divided into six groups. The chicks in Groups I, II, and III were given plant extract at three different concentrations: 4%, 5%, and 6%,... 

Plant ecology has long been concerned with determining the factors that influence distribution of plant species. A fundamental premise of plant ecophysiology is that the relationship between plants and their environmental elements is considerably influenced by plant distribution. Ecophysiology and plant distributions are therefore inextricably linked. This chapter elaborates on what is recognized about tropical trees’ responses to varying resource availability and how this knowledge is essential for designing a more comprehensive picture of the tropical forest’s capabilities to respond to a changing environment. At the minimum, five trends of interacting ecophysiological variables may enable... 

Nomex honeycomb composite (NHC) has been increasingly used in the automotive, aerospace and defence applications due to its excellent thermal and mechanical properties. Its complex cellular hexagonal thin-walled configuration along with heterogeneous, soft and brittle nature pose substantial processing defects such as burr formation, tearing of walls, surface roughness, dimensional inaccuracy and low machining quality during conventional machining (CM). These surface defects have a substantial influence on the operating life and functional performance of its sandwiched structural members. Hybrid ultrasonic vibration assisted machining (HUSVAM) technology has been introduced to overcome such... 

The applications of Nomex honeycomb composite (NHC) structures in aerospace, automotive and defence sectors have been significantly increasing due to their high compressive strength, hexagonal thin-walled structure, ultra-light weight and excellent thermal resistance. Specific applications include composite sandwich structures in helicopter propellers, satellite cabins, aeroplane floors, engine cowls, wings and nacelles. Accuracy of the machined surface of NHC structures is required for adhesive bonding with face-sheets. Conventional machining processes generate machining defects in terms of tearing, damaged cell walls, burr formation, delamination and poor surface quality that result in... 

In connection to present energy demand and waste management crisis in Pakistan, refuse-derived fuel (RDF) is gaining importance as a potential co-fuel for existing coal fired power plants. This research focuses on the co-combustion of low-quality local coal with RDF as a mean to reduce environmental issues in terms of waste management strategy. The combustion characteristics and kinetics of coal, RDF, and their blends were experimentally investigated in a micro-thermal gravi-metric analyzer at four heating rates of 10, 20, 30, and 40 °C/min to ramp the temperature from 25 to 1000 °C. The mass percentages of RDF in the coal blends were 10%, 20%, 30%, and 40%, respec-tively. The results show... 

Hemodialysis is a process in which the blood is resected using a dialysis apparatus and a specific strainer known as dialyzer. Poor nutritional status is common among hemodialysis patients, but only a few studies are found on how hemodialysis is affected by other factors in the local environment. The aim of this study was to find out hemodialysis patients' nutritional status and the factors that influence it. A total of 100 hemodialysis individuals (50 patients and 50 volunteers) was enrolled in this study. Anthropometry and biochemical assays, as well as nutrition assessments, were used as additional evaluation methods. According to multiple linear regression analysis, malnutrition is... 

This research work was conducted to investigate the anatomical and antioxidant studies of some ethnoveterinary grasses (Cenchrus pennisetiformis and Dichanthium annulatum). The anatomical characteristics (compact epidermal layer, large cortical cells, thickened sclerenchyma, central and scattered vascular bundles, large metaxylem, small protoxylem, and centrally located pith) were observed. For the antioxidant activity studies, the crude methanol extract was prepared by maceration techniques and different fractions were prepared (n-hexane, chloroform, and aqueous solution). The maximum antioxidant potential in DPPH was shown by C. pennisetiformis at a concentration of 250 µL in the... 

Estate administration involves managing and distributing a deceased individual’s assets to beneficiaries, as well as managing the liabilities. This process comprises legal, financial, and administrative tasks that ensure assets are transferred based on the deceased's wishes and in accordance with the law. In Southeast Asia countries such as Indonesia, Malaysia and Brunei where Muslims represents the majority of population, the Islamic law plays an integral part in the inheritance management as the process to be in line with the Islamic teachings and principle. The role of the syariah authority namely the syariah courts is prevalent and therefore, abidance to the rule under the syariah legal... 

A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network... 

Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the... 

With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost... 

Gaining insight into possible vibratory responses of dynamical systems around their stable equilibria is an essential step, which must be taken before their design and application. The results of such a study can significantly help prevent instability in closed-loop stabilized systems by avoiding the excitation of the system in the neighborhood of its resonance. This paper investigates nonlinear oscillations of a rotary inverted pendulum (RIP) with a full-state feedback controller. Lagrange’s equations are employed to derive an accurate 2-DoF mathematical model, whose parameter values are extracted by both the measurement and 3D modeling of the real system components. Although the governing... 

A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring... 

We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems. The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity. The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction. This signifies the potential of GT as a biocompatible matrix for...