Explore the vast range of titles available.

In the past few years, a new passion for the growth of biodegradable polymers based on elements derived from natural sources has been getting much attention. Natural fiber-based polymer matrix composites offer weight loss, reduction in cost and carbon dioxide emission, and recyclability. In addition, natural fiber composites have a minimal impact on the environment in regards to global warming, health, and pollution. Polylactic acid (PLA) is one of the best natural resource polymers available among biodegradable polymers. Natural fiber–reinforced PLA polymer composites have been extensively researched by polymer researchers to compete with conventional polymers. The type of fiber used plays a massive part in fiber and matrix bonds and, thereby, influences the composite’s mechanical properties and thermal properties. Among the various natural fibers, low density, high strength bamboo fibers (BF) have attracted attention. PLA and bamboo fiber composites play a vital character in an extensive range of structural and non-structural applications. This review briefly discussed on currently developed PLA-based natural bamboo fiber–reinforced polymer composites concentrating on the property affiliation of fibers. PLA polymer–reinforced natural bamboo fiber used to establish composite materials, various composite fabrication methods, various pretreatment methods on fibers, their effect on mechanical properties, as well as thermal properties and applications on different fields of such composites are discussed in this study. This review also presents a summary of the issues in the fabrication of natural fiber composites.

This study investigated the performance optimization of nickel-cobalt (Ni-Co)-coated absorber panels in solar flat plate collectors (SFPCs) using response surface methodology for sustainable operation and optimized performance. Ni-Co coatings, applied through an electroplating process, represent a novel approach by offering superior thermal conductivity, durability, and environmental benefits compared to conventional black chrome coatings, addressing critical concerns related to ecological impact and long-term reliability. Experiments were conducted to evaluate the thermal efficiency of Ni-Co-coated panels with and without reflectors under varying flow rates, collector angles, and reflector angles. The thermal efficiency was calculated based on the inlet and outlet water temperatures, solar radiation intensity, and panel area. The results showed that the SFPC achieved average efficiencies of 50.9% without reflectors and 59.0% with reflectors, demonstrating the effectiveness of the coatings in enhancing solar energy absorption and heat transfer. A validated quadratic regression model (R2 = 0.9941) predicted efficiency based on the process variables, revealing significant individual and interaction effects. Optimization using the Box–Behnken design identified the optimal parameter settings for maximum efficiency: a flow rate of 1.32 L/min, collector angle of 46.91°, and reflector angle of 42.34°, yielding a predicted efficiency of 79.2%. These findings highlight the potential of Ni-Co coatings and reflectors for enhancing SFPC performance and provide valuable insights into the sustainable operation of solar thermal systems. Furthermore, the introduction of Ni-Co coatings offers a sustainable alternative to black chrome, reducing environmental risks while enhancing efficiency, thereby contributing to the advancement of renewable energy technologies.

In this study, thrust force generation during drilling in natural fiber-reinforced epoxy has been investigated. Three natural fibers Abaca (A), Hemp (H) and Jute (J) have been utilized. Four different point angles of the twisted drill tools have been employed: 90°, 100°, 105° and 118°. The sequence of natural fiber-based specimens prepared for the studies as follows: A/H/A/H and H/J/H/J. The objective of this study is to find the drilling process parameters at lower thrust force. Also find the percentage of contribution of the drilling process parameters on the thrust force. Few authors has studied the drilling analysis using angle variation in the twisted drill bit however, no researches has been found in the drilling study of Hemp, Abaca and Jute by different angled twist drill bit. The result indicates that at 0.05 mm/rev feed rate and 3000 rpm spindle speed generated minimum thrust force of 4.6 N on abaca and hemp-based composites using 90°-point angle of the twisted drill bit. At 0.05 mm/rev, 3000 rpm and 90°-point angle of drill bit, produced minimum thrust force of 3.1 N on Hemp and Jute fiber-based composite. Thermal imager has been used to monitor temperature variation during the drilling of composite specimens. Defects in the specimen was identified by using scanning electron microscopic and microscopic images. The analysis of variance of the thrust force generated during drilling of the A/H/A/H and H/J/H/J based composite materials has performed using Minitab 21 software.

For comparison, the drilling behaviour of abaca fiber-reinforced polymer (AFRP) composites and Kevlar-reinforced epoxy polymer (KFRP) composites has been studied in the specified experimental condition. The different geometrical drilling tools have been used for the investigation, namely, candlestick (T1), core (T2), standard twist drill (T3), and step cone (T4). The tool feed of 30, 45, and 60 m/min and rotational speed of 1000, 1500, and 2000 rpm have been used for the investigation. The thrust force is chosen as a response parameter for this study. The results revealed that, at lesser rotational speed and tool feed, the thrust force has declined. The result obtained correlates with the abaca fiber-based systems. However, the thrust force of KFRP is higher compared to AFRP composite systems. The axial force generated by candlestick drill is minimal compared to the other drill bits. The following may be responsible for lower thrust force: (1) the axial force distributes circumferential of the cutting tool instead of focusing at the center and (2) the interfacial adhesiveness between the matrix and the fiber is higher. The optimization of drilling process parameters, namely, tool feed and rotational speed on thrust force, has been studied. The results reveal that the tool feed contributed more to axial force compared to rotational speed.

In this work, an analysis has been done on extended surfaces with various geometries to identify the better heat transfer rate. The geometries of extended surfaces namely - bar fins, stepped fins, stepped fins with indentations have been modelled, investigated and studied. Based on the design identification and numerical analysis the extended surfaces with increases surface area has increased heat transfer. From numerical data the fins with indentations has increased surface area and heat transfer. The indentations have been designed with varying diameter used in the fins are 4mm, 3mm, 2mm respectively and analysed using a fixed computational method. It is found that the spherical notches with varying diameter were more effective than the other fins and making the notches increases the heat transfer was much effective than increasing the diameter of the indentation in the stepped fin. This work shows the design, analysis, and result of some extended surface geometries with fixed input boundary condition.

The most challenging task in the supply chain is selecting the appropriate supplier, and it has a great influence on industry productivity growth. Because of the large budget allotted to raw materials, supplier selection is a critical issue for the industry’s financial status. The right supplier in the industry drastically reduces problems throughout the supply chain. The several managers of a company were interviewed, and the most essential criteria considered by the managers when choosing their supplier firms were identified. In this study, Fuzzy-AHP and goal programming are combined to identify suitable suppliers and allocate orders in the supply chain. The mathematical models developed the goals of minimizing periodic budget, minimizing defect rate, maximizing the total value of purchase, and maximizing demand. To reach the desired values of periodic goals, the multiobjective multi-integer linear programming model is presented. A mathematical example is offered to show the effectiveness of suggested method. The Archimedean goal programming method is used to solve these multiple periods of single products within the Lingo 18.0 software package. Multiple period demand allocations to suppliers are calculated as X11 = 9000, X12 = 7800, X13 = 7900, X21 = 3434.9, X22 = 5098, X23 = 6002.56, X31 = 100, X32 = 100, and X33 = 100. All the target values of budget, defective rate, and demand are achieved for all periods except the total values of purchasing. The results are subjected to sensitivity analysis. It will help a manufacturer for selecting a suitable supplier to allocate the order for maximizing the profit, improving the quality of product, enhancing the supplier buyer relationship, strengthening the supply chain, reducing the risk of purchasing decision, and improving customer satisfaction. Therefore, the supply chain is effective to supply the continuity of products.

In this research, microstructural events and mechanical behaviors in dissimilar friction stir welding (FSW) of aluminium (Al) alloy AA6082-AA7075 joints have been evaluated to apply aerospace, defense, and military sectors. FSW parametric effects have a more significant impact on the mechanical performances and microstructure of produced joints. FSW tool rotational speed, welding speed, and tool plunge speed were chosen to make the weld joints. The rotational tool speeds of 1600 rpm and 2300 rpm, welding speeds of 40 mm/min and 60 mm/min, and tool plunge speeds of 20 mm/min and 30 mm/min were set as the upper and lower limits. A constant axial force of 5 kN was maintained throughout the joint fabrication process. A taper pin-profiled tool was utilized to produce the butt welded joints. Mechanical properties of microhardness, tensile strength, yield strength, elongation, and bending strength of the joints were analyzed. The response of the stir zone microstructure to processing parameters was evaluated using optical microscopy (OM) and fractographic analysis of a tensile specimen shown by scanning electron microscope (SEM). The weld joints produced at 2300 rpm, tool traveling rate of 40 mm/min, and tool plunge speed of 30 mm/min showed the greatest tensile strength of the 191 MPa hardness of 145 Hv at the weld center and also the maximum bending strength of 114.23 N/mm2 was achieved. The lowest bending strength of 25.38 N/mm2 was obtained at 1600 rpm with 60 mm/min due to inappropriate mixing of the base metals and poor joint quality. Furthermore, this study revealed that a higher tool plunge speed facilitates the formation of equiaxed grains in the thermomechanically affected zone (TMAZ) on the advancing side (AS). Additionally, the increment in tool rotational speed significantly improved the tensile strength, weld joint quality, and joint efficiency.

There is more demand for natural fiber-reinforced composites in the energy sector, and their impact on the environment is almost zero. Natural fiber has plenty of advantages, such as easy recycling and degrading property, low density, and low price. Natural fiber’s thermal properties and flexural properties are less than conventional fiber. This work deals with the changes in the thermal properties and mechanical properties of S-glass reinforced with a sodium hydroxide-treated pineapple leaf (PALF) and banana stem fibers. Banana stem and pineapple leaf fibers (PALF) were used at various volume fractions, i.e., 30%, 40%, and 50%, and various fiber lengths of 20 cm, 30 cm, and 40 cm with S-glass, and their effects on the thermal and mechanical properties were studied, and their optimum values were found. It was evidenced that increasing the fiber volume and fiber length enhanced the flexural and thermal properties up to 40% of the fiber volume, and started to decrease at 50% of the fiber volume. The fiber length provides an affirmative effect on the flexural properties and a pessimistic effect on the thermal properties. The PALF S-glass combination of 40% fiber load and 40 cm fiber length provides maximum flexural strength, flexural modulus, storage modulus, and lowest loss modulus based on hybrid Taguchi grey relational optimization techniques. PALF S-glass hybrid composite has been found to have 7.80%, 3.44%, 1.17% higher flexural strength, flexural modulus, and loss modulus, respectively, and 15.74% lower storage modulus compared to banana S-glass hybrid composite.

In this work, the solar water collector flow tube geometry is modified as curved and spiral to enhance the system’s performance. The investigation is carried out experimentally under the meteorological conditions of the Kovilpatti region (9°10′0″N, 77°52′0″E), Tamil Nadu, India. The flow pipes of the solar water heater are made of copper material which has higher thermal conductivity to recover the water heat as thermal energy. The influence of the mass flow rate (MF) on the flow pipes with respect to the surface temperature for various configurations of the flow tubes is investigated. The two MFs of 0.0045 kg/s and 0.006 kg/s are tested. The MF of 0.006 kg/s yields the maximum efficiency of 73% compared to the other MF. The straight, curved, and spiral tubes yielded the maximum efficiency of 58%, 62%, and 69%, respectively, at 0.0045 kg/s. Similarly, the MF of 0.006 kg/s obtained an efficiency of 62%, 65%, and 73% for straight, curved, and spiral flow tubes, respectively. The economics and exergy of the system are analyzed. The maximum exergy efficiency of the collector is estimated to be 32% for the MF of 0.0045 kg/s for the spiral flow collector, and for the 0.006 kg/s MF, the obtained exergy efficiency is 27% for the spiral flow water heater. The economic analysis revealed that the expense is $0.0608 and $0.0512 worth of hot water produced for the domestic space heating.

When the compaction of concrete becomes challenging to carry out, Self-Compacting Concrete (SCC) is considered as an alternative to ordinary concrete. The aim of the present work is to obtain high-strength SCC by substituting Ground Granulated Blast Furnace Slag (GGBFS) and Silica Fume (SF) for cement. GGBFS and SF have been extensively employed as admixtures in recent years to produce high-strength concrete. SCC was created as a reference mix without any mineral admixtures, whereas the other mixes had varying amounts of GGBS and SF. The remaining six mixtures contained various concentrations of GGBFS from 10 to 30 percent with variations of 10% and silica fume from 5 to 15 percent with variations of 5 percentile. As workability is the primary attribute of SCC, various flowability features, including the Slump test, V funnel, and L box test were recognized. Studies on mechanical performance and durability properties were conducted. At 28 days, a ternary combination of 30% GGBS and 5% SF reaches its maximum compressive strength of 70.12 MPa. Also, when SF is replaced with 5% and GGBFS with 30% by weight of cement, the results showed better improvement in durability.