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Industrial evolution and practical application of unusual methods for upgrading production procedures necessitate extensive studies in respective fields, particularly in the machining perspective. Higher yields and incomes are main factors for most of the manufacturers. Indeed, the substantial aim in manufacturing process is to optimize time of production, energy, cost, and resources while improving the function. Nowadays, exploitation of nanotechnology has gained great interest due to promising advantages toward higher yield in different processes. Hence, nanotechnology is considered in machining operations as nanofluid and coated cutting tools with nanoparticles. This review work attempts to represent a comprehensive review of the open literature describing recent advancements in machining application by using nanofluids. Basically, nanofluids could be beneficial in most of the cryogenic systems, heat transfer, and lubrication applications. Current study summarizes substantial aspects of utilizing novel nanofluids as coolant/lubricant with special focus on their impact on cutting parameters in various machining processes consisting of grinding, turning, milling, and drilling. Application of nanofluid enhances lubricant properties which leads to a high wettability and enables the lubrication process of the cutting zone much better while resulting in minimized frictional force. Therefore, cutting force could be reduced due to the reduction in frictional force. Nanofluid enable the production of the lowest surface roughness due to the inclusion of nanoparticles which boosts up the heat transfer rate and consequently improves the properties of the tool's rake face. Nanofluid prolongs the tool life due to the oil mist and the number of nanoparticles formed on flank face. The formed oil mist and nanoparticles in the cutting zone make possibility to create a film of barrier which eventually decreases the cutting force and tool wear. The application of nanofluids reduces tool wear by removing the heat from the primary shearing zone at faster rate and preventing the work piece hardening. Thus, the cutting tool can sustain longer the hardness of the work piece and prevent the tool wear issues. [ABSTRACT FROM AUTHOR]

In the modern world, zero-carbon society has become a new buzzword of the era. Many projects have been initiated to develop alternatives not only to the environmental crisis but also to the shortage of fossil fuels. With successful projects in automobile technology, hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector which will lead to zero carbon emission in the future. From the mid-20th century to the early 21st numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. Empirical data show positive results for various projects. Consequently, large companies are investing in various innovations undertaken by researchers under their supervision. Over time, the efficiency of hydrogen-fueled aircraft has improved but the lack of refueling stations, large production cost, and consolidated carbon market share have impeded the path of hydrogen fuel being commercialized. In addition, the Unmanned Aerial Vehicle (UAV) is another important element of the Aviation industry, Hydrogen started to be commonly used as an alternative fuel for heavy-duty drones using fuel cell technology. The purpose of this paper is to provide an overview of the chronological development of hydrogen-powered aircraft technology and potential aviation applications for hydrogen and fuel cell technology. Furthermore, the major barriers to widespread adoption of hydrogen technology in aviation are identified, as are future research opportunities. [Display omitted] • Hydrogen is extensively researched and acknowledged as a viable mainstream fuel option. • Hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector. • Numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. • Empirical data show positive results for various projects. • New engine modules have been designed to accommodate hydrogen fuel cells economically. [ABSTRACT FROM AUTHOR]

3D printing technology has revolutionized free-form construction and customization demand through its ease of use, fast production, accurate, regulated deposition, and flexibility with soft functional materials. Fused deposition modeling (FDM) is an ideal technique for the 3D printing of plastics. The low cost, high prototyping precision, and ease of use make it a popular additive manufacturing process. The dimensional stability, quality, functionality, and properties of printed specimens are all affected by the process parameters used in the FDM technology. As such, the present work investigates the effect of the infill pattern and infill density on the PETG mechanical characteristics. The work also finds the optimum parameters to enhance the mechanical properties using the response surface methodology (RSM). Scanning electron microscopy (SEM) was used to study micro-surface defects under different processing conditions. Based on the tensile strength experiments, the concentric pattern was recorded to have the highest UTS, E, and yield values compared to the other designs, at 28.53 MPa, 0.81 GPa, and 20.00 MPa, respectively. In contrast, from compression analysis, the highest compression strength and compression modulus (24.03 MPa and 3.71 GPa, respectively) were obtained for the triangular infill pattern, which absorbs more compressive force compared with the other patterns. Meanwhile, it was also observed that increasing the density from 25 to 75% improves mechanical properties. The RSM analysis reveals the significant parameters for both testing methodologies with mathematical models to predict the properties with 95% certainty. [ABSTRACT FROM AUTHOR]

This paper presents to develop first-order models for predicting the cutting temperature for end-milling operation of Hastelloy C-22HS by using four different coated carbide cutting tools and two different cutting environments. The first-order equations of cutting temperature are developed using the response surface methodology (RSM). The cutting variables are cutting speed, feed rate, and axial depth. The analyses are carried out with the aid of the statistical software package. It can be seen that the model is suitable to predict the longitudinal component of the cutting temperature close to those readings recorded experimentally with a 95% confident level. The results obtained from the predictive models are also compared with results obtained from finite-element analysis (FEA). The developed first-order equations for the cutting temperature revealed that the feed rate is the most crucial factor, followed by axial depth and cutting speed. The PVD coated cutting tools perform better than the CVD-coated cutting tools in terms of cutting temperature. The cutting tools coated with TiAlN perform better compared with other cutting tools during the machining performance of Hastelloy C-22HS. It followed by TiN/TiCN/TiN and CVD coated with TiN/TiCN/Al2O3 and TiN/TiCN/TiN. From the finite-element analysis, the distribution of the cutting temperature can be discussed. High temperature appears in the lower sliding friction zone and at the cutting tip of the cutting tool. Maximum temperature is developed at the rake face some distance away from the tool nose, however, before the chip lift away. [ABSTRACT FROM AUTHOR]

The escalating significance of 3D printing in various industries is underscored by its ability to rapidly and cost-effectively produce distinctive parts. Among the 3D printing methods, fused filament fabrication (FFF) has emerged as a highly productive and cost-effective approach. While extensive efforts have been made to enhance the qualities of FFF products, challenges persist in material availability and quality compared to traditional methods. This study provides a meticulous overview of the FFF process, delving into various 3D printing processes, polymers, and polymer composites. Despite documented efforts to augment mechanical, thermal, and electrical properties, material constraints remain a focal point. Our analysis extends to various PLA/biocomposites, shedding light on achieved improvements and potential applications. Looking forward, the future trend in FFF technology suggests a paradigm shift towards enhanced material diversity and performance. Anticipated applications span beyond traditional use cases, encompassing sustainable manufacturing, medical devices, and eco-friendly construction materials. This comprehensive review not only consolidates the current state of FFF and PLA-biocomposites but also anticipates future trends and potential applications. This research enhances the current knowledge of additive manufacturing and sets a standard for assessing developments in FFF technology by comparing them to previous works. [ABSTRACT FROM AUTHOR]

In recent years, 3D printing technology has played an essential role in fabricating customized products at a low cost and faster in numerous industrial sectors. Fused deposition modeling (FDM) is one of the most efficient and economical 3D printing techniques. Various materials have been developed and studied, and their properties, such as mechanical, thermal, and electrical, have been reported. Numerous attempts to improve FDM products' properties for applications in various sectors have also been reported. Still, their applications are limited due to the materials' availability and properties compared to traditional fabrication methods. In 3D printing, the process parameters are crucial factors for improving the product's properties and reducing the machining time and cost. Researchers have recently investigated many approaches for expanding the range of materials and optimizing the FDM process parameters to extend the FDM process's possibility into various industrial sectors. This paper reviews and explains various techniques used in 3D printing and the various polymers and polymer composites used in the FDM process. The list of mechanical investigations carried out for different materials, process parameters, properties, and the FDM process's potential application was discussed. This review is expected to indicate the materials and their optimized parameters to achieve enhanced properties and applications. Also, the article is highly anticipated to provide the research gaps to sustenance future research in the area of FDM technologies. [ABSTRACT FROM AUTHOR]

Processing complex parts with high dimension accuracy and cost-effectiveness can be achievable using the fused deposition modeling (FDM) technique. It is one of the highly efficient methods in the additive manufacturing process. However, limitation in working temperature is the main drawback associated with the FDM technique, which has caused the applicability of low melting temperature materials in this technology, such as PLA. Lack of mechanical strength and critical parameters such as thermal/electrical conductivity in the final printed products through the FDM technique is another deficiency in this manufacturing process. The problems mentioned above have gained researchers' attention to explore new composite materials as filament for FDM technology. In this research work, copper-reinforced polylactic acid (PLA) specimens are printed with copper composition variation (25 and 80 wt.%) and various infill patterns including rectilinear, grid, concentric, octagram-spiral, and honeycomb to investigate its mechanical properties. The geometry of test specimens was fabricated according to ASTM standard using a low-cost FDM printer. The mechanical properties consist of tensile properties, flexural properties, and compression properties. The highest ultimate tensile strength (UTS) is obtained by applying 25 wt.% copper composition and concentric infill pattern recording 25.20 MPa. In contrast, the flexural strength revealed the maximum value of 38.53 MPa. The highest compressive strength is obtained by grid infill pattern with 25.94 MPa for 25 wt.% Cu compositions. Response surface methodology (RSM) has been executed to evaluate the influencing parameters, and mathematical models to predict the mechanical properties have been proposed to estimate the properties. [ABSTRACT FROM AUTHOR]

Flat plate solar collectors can easily be termed as the most vastly studied alternative energy transforming and generating technology of the twenty-first century. As the world is racing towards the fourth industrial revolution (Industry 4.0), more and more energy is being consumed for mega projects to be materialized. Electronic devices are not only confined to conventional intermittent and costlier electric energy, but also fuel. Solar energy is now being shared to work smart devices, transform electric energy, and operate automobiles, aeronautics, water heating, and space heating. Traditional flat plate solar collectors can only occupy 50–60% of their thermal efficiency, resulting in less heat generation and a low thermal performance because of using a common absorber made of copper tubing compared to a high conductive metal sheet (copper or aluminum). To ameliorate the thermal efficiency of the solar collector, it is imperative to find a superior alternative heat exchanger that will result in improved thermal performance of the solar collector. In this study, light has been shed in terms of substituting conventional heat absorbers with crystal nano-cellulose (CNC) and a graphene hybrid. An empirical comparison has been drawn by comparing the familiar 0.3% base fluid, 0.5% graphene, and CNC separately, as well as 0.3%, 0.5% CNC, and graphene hybrids at different temperatures. Remarkably, this work has proven that a CNC and graphene hybrid fluid with a volumetric fraction of 0.5% concentration and at a high temperature of 80 °C, gave astounding results for improved thermal conductivity, viscosity, and other parameters. CNC and graphene hybrid nanofluid can be a superior substitute for a conventional base fluid, resulting in prolific thermal performance. [ABSTRACT FROM AUTHOR]

Friction and wear are the main factors in the failure of the piston in automobile engines. The objective of this work was to improve the tribological behaviour and lubricant properties using hybrid Cellulose Nanocrystal (CNC) and Copper (II) oxide nanoparticles blended with SAE 40 as a base fluid. The two-step method was used in the hybrid nanofluid preparation. Three different concentrations were prepared in a range of 0.1% to 0.5%. Kinematic viscosity and viscosity index were also identified. The friction and wear behavior were evaluated using a tribometer based on ASTM G181. The CNC-CuO nano lubricant shows a significant improvement in term of viscosity index by 44.3–47.12% while for friction, the coefficient of friction (COF) decreases by 1.5%, respectively, during high and low-speed loads (boundary regime), and 30.95% during a high-speed, and low load (mixed regime). The wear morphologies results also show that a smoother surface was obtained after using CNC-CuO nano lubricant compared to SAE 40. [ABSTRACT FROM AUTHOR]

[Display omitted] • The economic viability and sustainability of H 2 -generating technologies are assessed. • Challenges of controlling hydrogen cost based on production, materials, and storage. • The goal of future research should be to reduce the cost of producing renewable H 2. • In-depth descriptions of recent developments, difficulties, and opportunities are provided. The world's fossil fuel supplies are being depleted at an accelerated rate, and the demand for these resources is only growing. In addition, fossil fuels which provide 80% of the world's basic energy have detrimental effects on the ecosystem, mostly through the emission of greenhouse gases that exacerbate climate change. The urgency of swiftly shifting from conventional energy sources to sustainable or renewable alternatives that can meet present and future global energy demands is highlighted by the environmental crisis that is worsening. As an energy carrier, hydrogen emerges as a strong contender in this transition, and the cost of production of hydrogen is also associated. Thus, to provide a competitive analysis of the cost of hydrogen production, a thorough literature review was conducted. This literature review looks into both basic and advanced hydrogen production technologies, evaluating their cost-efficiency profiles. Comparing the cost of hydrogen production from various sources becomes critical in the pursuit of sustainable energy generation. It can quantify production costs by using powerful data analytics techniques. This entails meticulously collecting and preparing relevant cost data, identifying critical metrics, and employing statistical methodologies. Cost dynamics analysis includes descriptive analysis, data visualization, and rigorous statistical testing. According to the findings of this analysis, steam methane reforming technology has an impressive efficiency rate of 85% and a production cost of 2.27 USD/unit of hydrogen. Notably, while electrolysis produces cleaner hydrogen, its high energy consumption makes it more expensive than the less expensive SMR technology. Furthermore, regression analysis allows us to thoroughly examine potential influencing factors. Through rigorous data analysis, for example, a clearer image of the cost-effectiveness of different hydrogen sources might be created, enabling more informed decision-making in the field of sustainable energy generation. [ABSTRACT FROM AUTHOR]

This paper reports experimental investigation on the viscosity, electrical and thermal conductivities of ethylene glycol and propylene glycol based β-SiC nanofluids. Two-step technique was used to formulate stable nanofluids at room temperature. The properties of nanofluids were measured at temperatures between 298.15 K and 353.15 K for different concentrations up to 3.0 wt.% loading (1.0 vol.%). The effect of temperature and base liquid was analysed on each of nanofluid sample. The experimental results showed that both electrical and thermal conductivity increase while viscosity decreases with temperature. The properties of the base liquid are found to influence the nanofluid properties. The underlying mechanisms have been established and discussed. Furthermore, some new empirical equations are derived to correlate the measured properties data. The results can be applied to predict the viscosity, electrical and thermal conductivities of ethylene glycol and propylene glycol-based β-SiC nanofluids. Unlabelled Image • Measuring viscosity, electrical and thermal conductivities of β-SiC/glycols nanofluids • Fluid viscosity detrimental to electrical and thermal conductivities enhancements • High temperature impactful on measured properties for heat transfer • Correlation of properties data with empirical equations [ABSTRACT FROM AUTHOR]

[Display omitted] • CNC-MXene nanolubricant explored for Tribology Application. • CNC nanolubricants are the most stable nanolubricant compared to CNC-MXene nanolubricant. • Zeta potential distribution for CNC, MXene, and CNC-MXene nanoparticles rises with concentration. • At 90 °C, the solid concentration of 0.05% CNC-MXene resulted in the greatest increase in thermal conductivity ratio. • Viscosity of the base oil was improved by 16.77 % to 20.33 % The primary objective of the present work is to carry out an experimental study into the stability and thermophysical characteristics of cellulose nanocrystal, MXene, and hybrid cellulose nanocrystal-MXene added to engine oil as a lubricant for piston ring-cylinder liner application. There have been experiments with stability techniques like sedimentation observation, UV–visible spectroscopy, and zeta potential. Thermophysical characteristics have been measured using the viscosity index, dynamic viscosity, and thermal conductivity at various concentrations (ranging from 0.01 % to 0.05 %) and temperatures (from 40 °C to 100 °C). Even without any surfactants, the cellulose nanocrystal-MXene nanolubricants showed good dispersion during the first seven days. The results of the ultraviolet–visible spectrophotometer indicate that cellulose nanocrystal nanolubricants exhibit an absorbance ratio that is most similar to one. It can be shown that the zeta potential increases with a concentration in the distribution of cellulose nanocrystal, MXene, and cellulose nanocrystal-MXene nanoparticles. According to the viscosity index results, all nanolubricants reduce the lubricity oil's viscosity by 16.77 % to 20.33 %, with cellulose nanocrystal-MXene showing the greatest improvement at 0.05 %. At solid concentrations of 0.01 % cellulose nanocrystal and 0.05 % cellulose nanocrystal-MXene with temperatures of 40 °C and 90 °C, the dynamic viscosity was enhanced by 0.92 % and 130.87 %, respectively. The solid concentration of 0.05 % cellulose nanocrystal-MXene was determined to have the greatest effect on the thermal conductivity ratio of the chosen nanolubricant at 90 °C. Overall, at an average concentration of 0.05 %, the thermophysical properties' performance was increased by the addition of cellulose nanocrystal-MXene nanoparticle. The study's findings may be useful for applications involving heat transmission, particularly tribological ones. [ABSTRACT FROM AUTHOR]

Primary material supply is the heart of engineering and sciences. The depletion of natural resources and an increase in the human population by a billion in 13 to 15 years pose a critical concern regarding the sustainability of these materials; therefore, functionalizing renewable materials, such as nanocellulose, by possibly exploiting their properties for various practical applications, has been undertaken worldwide. Nanocellulose has emerged as a dominant green natural material with attractive and tailorable physicochemical properties, is renewable and sustainable, and shows biocompatibility and tunable surface properties. Nanocellulose is derived from cellulose, the most abundant polymer in nature with the remarkable properties of nanomaterials. This article provides a comprehensive overview of the methods used for nanocellulose preparation, structure–property and structure–property correlations, and the application of nanocellulose and its nanocomposite materials. This article differentiates the classification of nanocellulose, provides a brief account of the production methods that have been developed for isolating nanocellulose, highlights a range of unique properties of nanocellulose that have been extracted from different kinds of experiments and studies, and elaborates on nanocellulose potential applications in various areas. The present review is anticipated to provide the readers with the progress and knowledge related to nanocellulose. Pushing the boundaries of nanocellulose further into cutting-edge applications will be of particular interest in the future, especially as cost-effective commercial sources of nanocellulose continue to emerge. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) is used in this study to optimize the thermal characteristics of single graphene nanoplatelets and hybrid nanofluids utilizing the miscellaneous design model. The nanofluids comprise graphene nanoplatelets and graphene nanoplatelets/cellulose nanocrystal nanoparticles in the base fluid of ethylene glycol and water (60:40). Using response surface methodology (RSM) based on central composite design (CCD) and mini tab 20 standard statistical software, the impact of temperature, volume concentration, and type of nanofluid is used to construct an empirical mathematical formula. Analysis of variance (ANOVA) is applied to determine that the developed empirical mathematical analysis is relevant. For the purpose of developing the equations, 32 experiments are conducted for second-order polynomial to the specified outputs such as thermal conductivity and viscosity. Predicted estimates and the experimental data are found to be in reasonable arrangement. In additional words, the models could expect more than 85% of thermal conductivity and viscosity fluctuations of the nanofluid, indicating that the model is accurate. Optimal thermal conductivity and viscosity values are 0.4962 W/m-K and 2.6191 cP, respectively, from the results of the optimization plot. The critical parameters are 50 °C, 0.0254%, and the category factorial is GNP/CNC, and the relevant parameters are volume concentration, temperature, and kind of nanofluid. From the results plot, the composite is 0.8371. The validation results of the model during testing indicate the capability of predicting the optimal experimental conditions. [ABSTRACT FROM AUTHOR]

The use of insects as a biofuel feedstock has received limited research, and little is known about the fuel characteristics of insect biofuel. Fuel properties characterization can guide researchers focused on renewable fuel for the internal combustion engine. Therefore, this investigation focused on the physical-chemical properties modification of Hermetia illucens larvae oil (HILO) and diesel fuel blends, which could highly become an alternative renewable fuel. Five test fuel blends of HILO and diesel fuel were prepared at 0%, 25%, 50%, 75%, and 100% on a volume basis. Fuel properties such as chemical composition, density, viscosity, heating value, cetane number, and flash point of the test fuel blends were analyzed and compared to the diesel fuel. The main physical-chemical properties of HILO-diesel fuel blends were determined following the ASTM standards. Based on the results, the density, viscosity, cetane number, and flash point of the diesel fuel-HILO fuel blends were increased by 11.28%, 740.30%, 16.92%, and 86.67%, respectively, with the addition of HILO, except for the heating value reduced by 13.66%. [ABSTRACT FROM AUTHOR]

Nanofluids are identified as advanced working fluids in the solar energy conversion field with superior heat transfer characteristics. This research work introduces carbon-based diamond nanomaterial and Therminol®55 oil-based nanofluids for implementation in a concentrated photovoltaic/thermal (CPV/T) solar collector. This study focuses on the experimental formulation, characterization of properties, and performance evaluation of the nanofluid-based CPV/T system. Thermo-physical (thermal conductivity, viscosity, and rheology), optical (UV-vis and FT-IR), and stability (Zeta potential) properties of the formulated nanofluids are characterized at 0.001–0.1 wt.% concentrations of dispersed particles using experimental assessment. The maximum photo-thermal energy conversion efficiency of the base fluid is improved by 120.80% at 0.1 wt.%. The thermal conductivity of pure oil is increased by adding the nanomaterial. The highest enhancement of 73.39% is observed for the TH-55/DP nanofluid. Furthermore, dynamic viscosity decreased dramatically across the temperature range studied (20–100 °C), and the nanofluid exhibited dominant Newtonian flow behavior, with viscosity remaining nearly constant up to a shear rate of 100 s−1. Numerical simulations of the nanofluid-operated CPV/T collector have disclosed substantial improvements. At a concentrated solar irradiance of 5000 W/m2 and an optimal flow rate of 3 L/min, the highest thermal and electrical energy conversion efficiency enhancements are found to be 11 and 1.8%, respectively. [ABSTRACT FROM AUTHOR]

Heat transfer and friction characteristics were numerically investigated, employing elliptical tube to increase the heat transfer rate with a minimum increase of pressure drop. The flow rate of the tube was in a range of Reynolds number between 10000 and 100000. The FLUENT software is used to solve the governing equation of CFD (continuity, momentum, and energy) by means of a finite volume method. The electrical heater is connected around the elliptical tube to apply uniform heat flux (3000 W/m²) as a boundary condition. Four different volume concentrations in the range of 0.25% to 1% and different TiO2 nanoparticle diameters in the range of 27 nm to 50 nm, dispersed in water are utilized. The CFD numerical results indicate that the elliptical tube can enhance heat transfer and friction factor by approximately 9% and 6% than the circular tube, respectively. The results show that the Nusselt number and friction factor increase with decreasing diameters but increasing volume concentrations of nanoparticles. [ABSTRACT FROM AUTHOR]

This paper discusses the findings of thermal comfort assessment at Malaysian automotive industry. Nine critical workstations were chosen as subjects for the study in order to determine the thermal comfort among workers at Malaysian automotive industry. The human subjects for the study comprises of the operators from tire receiving, dashboard assembly, drum tester, body assembly, seat assembly, door check assembly, stamping workstation, engine sub assembly, and paint shop of the factory. The environmental factors such as wet bulb globe temperature, relative humidity, air velocity, illuminance were measured using BABUC A apparatus and thermal comfort measurement equipment. Through questionnaire survey, the demographic data of subjects and their perceptions on thermal comfort at each workstation were assessed based on ISO Standard 7730 and thermal sensation scale using predicted mean vote. Then, predicted percentage of dissatisfied is used to estimate the thermal satisfaction of occupants. The results indicated that most of the workstations of the automotive industry are considered as uncomfortable. Tire receiving station is considered having better working environment compared to other stations with lowest predicted mean vote index of 1.09 to 1.41 and predicted percentage of dissatisfied of 46%. Meanwhile, the engine sub assembly station and paint shop of assembly are considered the worst thermal environment with the predicted mean vote index values ranging between 2.1 to 2.9 and predicted percentage of dissatisfied values of 81% to 99%. Therefore, these two workstations are considered not comfortable because the thermal sensation scale is warm and almost hot. [ABSTRACT FROM AUTHOR]

The development of carbon membranes for the separation of various gases has gained interest among researchers due to their superior performance in gas separation. The preparation of carbon membranes by blending materials has many advantages including time and cost effectiveness for tuning the properties of the membranes. Here we review the recent research progress that has been made in the context of breakthroughs and challenges in the development of carbon membrane materials. In addition, we provide information regarding carbon membrane fabrication in terms of the selection of precursors and additives, carbon membrane process conditions, and coating conditions that influence the performance of gas separation of the resulting carbon membranes. The perspectives and future research directions for carbon membranes are also presented. [ABSTRACT FROM AUTHOR]

The mismatch between stiffness of the femoral dense stem and host bone causes complications to patients, such as aseptic loosening and bone resorption. Three‐dimensional finite‐element models of homogeneous porous (HGP) and functionally graded porous (FGP) stems incorporating body‐centered cubic (BCC) structures are proposed in this article as an alternative to the dense stems. The relationship between the porosity and strut thickness of the BCC structure was developed to construct the finite‐element models. Three levels of porosities (20%, 50%, and 80%) were modeled in HGP and FGP stems. The porosity of the stems was decreased distally according to the sigmoid function (n = 0.1, n = 1 and n = 10) with 3 grading exponents. The results showed that FGP stems transferred 120%‐170% higher stresses to the femur (Gruen zone 7) as compared to the solid stem. Conversely, the stresses in HGP and FGP stems were 12%‐34% lower than the dense stem. The highest micromotions (105‐147 µm) were observed for stems of 80% overall porosity, and the lowest (42‐46 µm) was for stems of 20% overall porosity. Finally, FGP stems with a grading exponent of n = 10 resulted in an 11%‐28% reduction in micromotions. [ABSTRACT FROM AUTHOR]

Because of its potential to directly transform solar energy into heat and energy, without harmful environmental effects such as greenhouse gas emissions. Hybrid nanofluid is an efficient way to improve the thermal efficiency of solar systems using a possible heat transfer fluid with superior thermo-physical properties. The object of this paper is the study the latest developments in hybrid applications in the fields of solar energy systems in different solar collectors. Hybrid nanofluids are potential fluids with better thermo-physical properties and heat transfer efficiency than conventional heat transfer fluids (oil, water, ethylene glycol) with single nanoparticle nanofluids. The research found that a single nanofluid can be replaced by a hybrid nanofluid because it enhances heat transfer. This work presented the recent developments in hybrid nanofluid preparation methods, stability factors, thermal improvement methods, current applications, and some mathematical regression analysis which is directly related to the efficiency enhancement of solar collector. This literature revealed that hybrid nanofluids have a great opportunity to enhance the efficiency of solar collector due to their noble thermophysical properties in replace of conventional heat transfer working fluids. Finally, some important problems are addressed, which must be solved for future study. [ABSTRACT FROM AUTHOR]

In this study, an alternative fuel for compression ignition (CI) engines called tri-fuel emulsion was prepared using an ultrasonic emulsifier. The objective of the study is to investigate the effect of emulsifying settings and formulation ratio on the physicochemical properties of tri-fuel emulsions. Design of experiment (DOE) with the two-level factorial design was employed to analyze the effect of emulsifying settings such as time, amplitude, and cycle along with the variation ratio of tri-fuel emulsion components as control factors. Numbers of responses identified were important parameters that may contribute to microexplosion phenomenon in CI engine. Analysis of variance (ANOVA) was carried out for each response, and the results indicated that density, dynamic viscosity, surface tension, and average droplet size were influenced by specific preparation control factors. Furthermore, interaction among the control factors was found to affect the responses as well. Interaction means the effect of two factors together is different than what would be expected from each factor separately. Besides, the stability of the tri-fuel emulsion was observed for three months. Furthermore, a qualitative approach with a multiobjective lens digital microscope revealed the geometry of freshly made dispersed tri-fuel emulsion droplets. Microscopic examination on tri-fuel emulsion droplets has shown that the dispersed ethanol capsulated within diesel with the help of biodiesel is similar to a water in diesel emulsion and is dissimilar to commercial diesel mixed with fatty acid methyl esters found in the market. [ABSTRACT FROM AUTHOR]