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The present study deals with the chemical modification of polyethylene glycol (PEG) based on shear thickening fluids (STFs) and their application to improve the ballistic impact and quasi-static resistance performance of 3D E-glass fabrics. The carrier fluid (PEG 200) was modified with two different agents, oxalic acid and glutaric acid. The modified PEGs were then characterized by FTIR analysis. The rheological analysis of modified STF using glutaric (G/STF) and oxalic acid (O/STF) showed an improvement in peak viscosity by 10.33 and 3.28 times compared to pure STF (P/STF), respectively. Moreover, PEG modification resulted in higher chain length and a higher number of hydrophilic functional groups, representing superior media-particle interaction through abundant H-bonding. As a result of improved viscosity, the ballistic resistance and quasi-static performance of modified STF-treated fabrics were enhanced compared to that of P/STF-treated fabrics. A two-step artificial intelligence regression analysis was performed to predict quasi-static puncture resistance at different puncture speeds. The results showed a strong correlation between the load-deformation behavior and the loading speed. [ABSTRACT FROM AUTHOR]

Layered transition metal trihalide WI3 is a new candidate in the race for two-dimensional (2D) magnetic materials. We investigated the electronic band structure and magnetic anisotropy of its monolayer by applying an external electric field using first-principles calculations based on density functional theory. Our calculation predicted that the WI3 monolayer exhibits an antiferromagnetic (AFM) ground state with out-of-plane easy axis. The external electric field could not induce a transition from its antiferromagnetic to ferromagnetic ground state. Rather, its AFM ground state becomes more robust with the application of external perturbation (such as electric field). We found that WI3 is a semiconductor with an indirect electronic band gap of about 1.7 eV. The orbital-resolved band structure revealed that the valence band maximum and the conduction band minimum are mainly dominated by the d x 2 - y 2 and d z 2 orbitals of W, respectively. These two orbitals mainly contribute to the electronic transitions associated with the electronic band gap of the system. In addition, the application of an electric field tuned its band gap and induced a transition from semiconductor to metal at an electric field E = 1.0 V/Å due to the giant linear Stark effect. Based on mean field theory, we also predicted that the application of an electric field could tune the Neel temperature (TN) from 40 K to an elevated temperature, which is critical for the working of spintronic devices. Our investigation also includes an in-depth orbital-resolved analysis of electric field-dependent magnetic anisotropy of the WI3 monolayer. We predicted that the magnetic anisotropy energy (MAE) of the system is dependent on the applied electric field. The orbital-resolved MAE study showed that, unlike the CrI3 monolayer, the major contribution to MAE arises from the transition metal element W. [ABSTRACT FROM AUTHOR]

PLUCISE A82 (PW82) is considered one of the best phase change materials as it is economical, commercially viable, and eco-friendly. Unless there is a great need to optimize the number of parameters to investigate encapsulated PCMs with good performance, for the effective and practical applications of organic phase change materials, it is required to enhance their thermal conductivity. In this study, efforts were made to increase the thermal properties of phase change materials by seeding different nanoparticles. The direct synthesis method, in which the mixing of nanoparticles in paraffin wax (PW82) takes place, is used for the production of NEPCM. Differential scanning calorimeter and heat conduction experiments were used to evaluate the effect of variable concentration of nano-encapsulation on thermal storage and heat conduction characteristics of nano-enhanced PCM. The thermal storage feasibility was also determined. In this study, titania (TiO2), Ti3C2/MXene was mixed in PW82 in 0.1, 0.2, and 0.3 wt.%. The investigation was also carried out for hybrid nano-enhanced PCM in a hybrid combination of (TiO2), and Ti3C2 (MXene) in PW82, used in wt.% concentration of 0.1, 0.2, and 0.3. Doping of titania and MXene improves the specific heat capacity of PCM. For doping of 0.3 wt.% of TiO2–Ti3C2 in PCM, the specific heat is improved to 41.3%. A maximum increment in thermal conductivity of 15.6% is found for doping of TiO2–Ti3C2 0.3 wt.%. The dissociation temperature of this prepared nano-enhanced PCM increases by ~6% for 0.3 wt.% weight fraction. Therefore, this study demonstrates that the doping of TiO2 and Ti3C2 with PW82 to form a new class of NEPCMs has significant scope to enhance the thermal storage capacity of organic paraffin. [ABSTRACT FROM AUTHOR]

Artificial roughness on the absorber of the solar air heater (SAH) is considered to be the best passive technology for performance improvement. The roughened SAHs perform better in comparison to conventional SAHs under the same operational conditions, with some penalty of higher pumping power requirements. Thermo-hydraulic performance, based on effective efficiency, is much more appropriate to design roughened SAH, as it considers both the requirement of pumping power and useful heat gain. The shape, size, and arrangement of artificial roughness are the most important factors for the performance optimization of SAHs. The parameters of artificial roughness and operating parameters, such as the Reynolds number (Re), temperature rise parameter (ΔT/I) and insolation (I) show a combined effect on the performance of SAH. In this case study, various performance parameters of SAH have been evaluated to show the effect of distinct artificial roughness, investigated previously. Therefore, thermal efficiency, thermal efficiency improvement factor (TEIF) and the effective efficiency of various roughened absorbers of SAH have been predicted. As a result, thermal and effective efficiencies strongly depend on the roughness parameter, Re and ΔT/I. Staggered, broken arc hybrid-rib roughness shows a higher value of TEIF, thermal and effective efficiencies consistently among all other distinct roughness geometries for the ascending values of ΔT/I. This roughness shows the maximum value of effective efficiency equals 74.63% at a ΔT/I = 0.01 K·m2/W. The unique combination of parameters p/e = 10, e/Dh = 0.043 and α = 60° are observed for best performance at a ΔT/I higher than 0.00789 K·m2/W. [ABSTRACT FROM AUTHOR]

This paper presents the thermo-hydraulic performance of small conical ribs on the absorber plate of a solar energy air heater (SAH) using exergy analysis. Application of conical protrusion ribs on the absorber is an attractive solution for enhancing the thermal performance of a SAH. However, these ribs are also responsible for high friction losses and increased fan power consumption caused by the turbulent air flow. To optimize the rib design, it is vital to consider both thermal and hydraulic performance at the same time. The SAH was assessed using an analytic method which predicts the exergy efficiency under operating parameters (e.g., Reynolds number, solar insolation and temperature increase parameter). The following geometric quantities of ribs were evaluated for optimum exergy efficiency: the relative rib height (e/D), which was in the range between 0.200 and 0.044, and the relative rib pitch (p/e), which was in the range between 6 and 12. The combination of a relative rib height of 0.044 and relative rib pitch of 10 exhibits the highest exergy efficiency of 0.0202. The optimization of the rib geometric quantities parameters was performed by considering the temperature increase parameter, aiming to achieve maximum exergy efficiency. The combination of rib parameters e/D = 0.044 and p/e = 10 are noted to yield best performance when operating at a temperature increase parameter above 0.0141 K∙m2/W. [ABSTRACT FROM AUTHOR]

Present investigation characterizes solid particle erosion response of neat epoxy and crump rubber filled epoxy composites. Three types of composites were prepared by reinforcing crump rubber particles (10, 20 and 30 vol.%) in epoxy matrix. Neat epoxy samples were also prepared for comparison. Thermo gravimetric analysis revealed crump rubber composites have higher stability as compared with neat epoxy specimen. Differential scanning calorimeter tests reveal higher glass transition temperature for crump rubber composites as compared with neat epoxy specimens. Erosion rate of the samples have been studied for different angles of impingement (30, 45, 60 and 90°) and erodent impact velocity (30, 45 and 60 m/s). 30 vol.% of crump rubber reinforced epoxy composites reveal better resistance to erosion in comparison with other composites and neat epoxy; attributed to the elastic nature of crump rubber particles to absorb impact energy of erodent particles. For all the specimens, maximum erosion is noted at 60° angle of impingement indicating semi‐ductile response to erosion. Erosion efficiency and velocity exponent of samples also substantiate the semi‐ductile behavior. Morphology of the eroded surfaces was analyzed using scanning electron microscope. Property map is used to compare the results available from the literature with the present study. [ABSTRACT FROM AUTHOR]

The rare earth element Cerium substituted Strontium hexaferrite SrFe12-xCexO19(x = 0.0–0.60), prepared using cost-effective sol–gel a citrate precursor auto-combustion technique at annealing temperature 850 °C. Systematic decrease in crystalline size (79.64–66.02 nm), strain, and systematic increase in cell volume with an increase in the composition of Cerium were found. TGA shows a total weight loss of 43%, while DTA depicts two endothermic peaks at 34 °C and 395 °C and one exothermic peak at 76 °C and thus proves helpful in analyzing the thermal behavior of SrFe12O19. FTIR spectrum shows shifting of the peak toward lower wave number, and hence decrease in force constant and bond length is observed. The largest and minimum value of force constant in tetrahedral and octahedral sites are found to be 262.987 N/m, 260.360 N/m, and 141.257 N/m, 139.973 N/m, respectively. Decrease in stiffness constant C11 (from 344.389 to 339.872), C12 (from 127.376 to 125.706 GPa) and elastic moduli, Y (from 275.60 to 271.991 GPa), B (from 199.713 to 197.094 GPa), G (108.50–107.083 GPa) is observed. PL spectra show four peaks in the visible region and an intense peak is observed for X = 0.40 composition. Visible region luminescence peaks may support its applications in opto-electronics and biological imaging. The highest saturation magnetization is obtained for SrFe11.80Ce0.20O19 hexaferrite sample of the order 54.24 emu/gm. The pattern of regular increment in coercivity is obtained from X = 0.00–0.40 with an order of 2421–5632 Oersted. In the SrFe12O19 sample, incorporation of Ce3+ composition profitably hinders the leakage current with maximal value of Pmax, Pr and Ec that are 14.13 μ c/cm2, 50.84 μ c/cm2 and 4.33171 kV/cm, respectively, for X = 0.60 composition and regular pattern increment is seen with increasing Ce3+ composition. Thus tuning of structural, magnetic, luminescence and ferroelectric properties of Strontium hexaferrite with Ce3+ substitution may help its uses as electronics and electrical material for its numerous applications in Electronics, Electrical and Environmental sectors. [ABSTRACT FROM AUTHOR]

Bio-char has the ability to isolate carbon in soils and concurrently improve plant growth and soil quality, high energy density and also it can be used as an adsorbent for water treatment. In the current work, the characteristics of four different types of bio-chars, obtained from slow pyrolysis at 375 °C, produced from hard-, medium-, thin- and paper-shelled walnut residues have been studied. Bio-char properties such as proximate, ultimate analysis, heating values, surface area, pH values, thermal degradation behavior, morphological and crystalline nature and functional characterization using FTIR were determined. The pyrolytic behavior of bio-char is studied using thermogravimetric analysis (TGA) in an oxidizing atmosphere. SEM analysis confirmed morphological change and showed heterogeneous and rough texture structure. Crystalline nature of the bio-chars is established by X-ray powder diffraction (XRD) analysis. The maximum higher heating values (HHV), high fixed carbon content and surface area obtained for walnut shells (WS) samples are found as ~ 18.4 MJ kg−1, >80% and 58 m2/g, respectively. Improvement in HHV and decrease of O/C and H/C ratios lead the bio-char samples to fall into the category of coal and confirmed their hydrophobic, carbonized and aromatized nature. From the Fourier transform infra-red spectroscopy (FTIR), it is observed that there is alteration in functional groups with increase in temperature, and illustrated higher aromaticity. This showed that bio-chars have high potential to be used as solid fuel either for direct combustion or for thermal conversion processes in boilers, kilns and furnace. Further, from surface area and pH analysis of bio-chars, it is found that WS bio-chars have similar characteristics of adsorbents used for water purifications, retention of essential elements in soil and carbon sequestration. [ABSTRACT FROM AUTHOR]