Mass Fraction Research Articles

Enhancing the Thermal Conductivity and Shape Stability of Phase-Change Composites Using Diatomite and Graphene Nanoplates for Thermal Energy Storage

The effects of mixing diatomite and graphene nanoplatelets (GNP) with xylitol were examined in this study. Form stability and thermal conductivity were also evaluated. According to the experimental results, the PCM composites exhibited a thermal conductivity of 0.403 W/mK. Melting and solidification points were determined by differential scanning calorimetry (DSC) to be 89.0°C and 36.5°C, respectively. To maximize the thermal characteristics of the PCM, the response surface methodology (RSM) was utilized to create prediction models for thermal conductivity based on the mass fractions of diatomite and GNP. These findings highlight the importance of understanding how the introduction of nanoparticles affects thermal properties. The prospective use of PCM in thermal energy storage is enhanced by its higher solidification enthalpy, noteworthy thermal stability, and insights into the impacts of diatomite and GNP.

The effect of anti-agglomerant tween on the thermal and rheological properties of TBAF semi-clathrate hydrate slurry used for cold storage systems

Hydrate, as a phase change cold storage material, can form the slurry with certain fluidity, enabling convective heat transfer during both the heat absorption and heat release stages (cold storage or refrigeration), with high heat transfer efficiency. However, high viscosity and significant flow pressure losses are the principal challenges limiting its advancement. The paper selected four non-ionic surfactants as hydrate anti-agglomerants (Tween 20, 40, 60, 80) and utilized DSC to examine their effects on the thermal properties of TBAF semi-clathrate hydrate slurry at three theoretical hydrate concentrations (with mass fraction of 0.60, 0.70, and 0.80). Additionally, it measured the viscosity variation during the endothermic dissociation stage of the TBAF hydrate slurry and calculated the flow pressure losses in hydrate slurries within various pipe diameters. The results revealed that the presence of Tween increased the hydrate growth within the slurry, resulting in a higher available phase change enthalpy. Tween 80 demonstrated the most significant increase in enthalpy increasing effect, with an available phase change enthalpy ranging from 128.08 to 170.03 kJ/(kg·slurry) and an increase in enthalpy of 52.14 % to 91.62 %. For TBAF hydrate slurries with the theoretical hydrate mass fraction of 0.60, the addition of Tween 20 or Tween 80 significantly reduced viscosity, dropping to between 57.6 mPa·s and 116 mPa·s, and reducing viscosity by 43.4 % to 71.9 %. Furthermore, most flows with anti-agglomerants were in the laminar regime. The addition of Tween 20 and Tween 80 achieved the maximum reduction in flow pressure loss per unit length, with the highest reduction being 80.2 % (0.11 kPa/m) and 71.1 % (0.15 kPa/m), respectively. Both the phase change enthalpy of the hydrate and the viscosity of the hydrate slurry impacted the flow pressure drop within pipes. Increasing phase change enthalpy and reducing viscosity are effective strategies for mitigating flow pressure drop.

Skeletal Kinetics Reduction for Astrophysical Reaction Networks

A novel methodology is developed to extract accurate skeletal reaction models for nuclear combustion. Local sensitivities of isotope mass fractions with respect to reaction rates are modeled based on the forced optimally time-dependent (f-OTD) scheme. These sensitivities are then analyzed temporally to generate skeletal models. The methodology is demonstrated by conducting skeletal reduction of constant density and temperature burning of carbon and oxygen relevant to Type Ia supernovae (SNe Ia). The 495-isotopes Torch model is chosen as the detailed reaction network. A map of maximum production of 56Ni in SNe Ia is produced for different temperatures, densities, and proton-to-neutron ratios. The f-OTD simulations and the sensitivity analyses are then performed with initial conditions from this map. A series of skeletal models are derived and their performances are assessed by comparison against currently existing skeletal models. Previous models have been constructed intuitively by assuming the dominance of α-chain reactions. The comparison of the newly generated skeletal models against previous models is based on the predicted energy release and 44Ti and 56Ni abundances by each model. The consequences of y e ≠ 0.5 in the initial composition are also explored where y e is the electron fraction. The simulated results show that 56Ni production decreases by decreasing y e as expected, and that the 43Sc is a key isotope in proton and neutron channels toward 56Ni production. It is shown that an f-OTD skeletal model with 150 isotopes can accurately predict the 56Ni abundance in SNe Ia for y e ≲ 0.5 initial conditions.

Properties, structure and mechanism of high-temperature modified steel slag based on solid waste

In this study, a composite modifier (CMCDL) containing coal gasification residue, dicyandiamide waste slag, and lake sediments was used to modify steel slag at high-temperature. Five kind of raw materials was analyzed in physicochemical properties, mineral composition and microstructure, cementitious properties and soundness, and particle size analysis, the same to steel slag after high-temperature modification (SHTM). The new mineral phases were found that tricalcium aluminate (C3A), gehlenite (C2AS), magnetite (Fe3O4), spinels (MgFe2O4), quartz (SiO2), celite (C6AF2) and diopside (CMS2) formed in the SHTM when the mass fraction increase from 10% to 30% in CMCDL. The HTM with CMCDL increases the glass phase and hydrated mineral (C3A, C3S, C2S) and in raw steel slag, promoting the disassembled of RO phase, turning the phase from FeO into MgFe2O4 and Fe3O4. MgFe2O4 and Fe3O4 have similar crystal structures, and they form mixed spinels. When the content of CMCCL (coal gasification residue: dicyandiamide waste slag: lake sediments =7:9:4) is 20%, the temperature is 1250 °C, result showed that the mass fraction of f-CaO in SHTM using CMCCL decreases from 4.81% to 1.86%, with a decrease of 61.3%, the 28-day activity index of SHTM increases up to 17.6% compared with raw steel slag, reaching 86.2%. Therefore, the CMCDL-blended SHTM can be applied harmlessly in cement and concrete, enabling low-energy fine grinding of steel slag.

Elevational variation in morphology and biomass allocation in carpathian snowbell Soldanella carpatica (Primulaceae)

Plants growing along wide elevation gradients in mountains experience considerable variations in environmental factors that vary across elevations. The most pronounced elevational changes are in climate conditions with characteristic decrease in air temperature with an increase in elevation. Studying intraspecific elevational variations in plant morphological traits and biomass allocation gives opportunity to understand how plants adapted to steep environmental gradients that change with elevation and how they may respond to climate changes related to global warming. In this study, phenotypic variation of an alpine plant Soldanella carpatica Vierh. (Primulaceae) was investigated on 40 sites distributed continuously across a 1,480-m elevation gradient in the Tatra Mountains, Central Europe. Mixed-effects models, by which plant traits were fitted to elevation, revealed that on most part of the gradient total leaf mass, leaf size and scape height decreased gradually with an increase in elevation, whereas dry mass investment in roots and flowers as well as individual flower mass did not vary with elevation. Unexpectedly, in the uppermost part of the elevation gradient overall plant size, including both below-and aboveground plant parts, decreased rapidly causing abrupt plant miniaturization. Despite the plant miniaturization at the highest elevations, biomass partitioning traits changed gradually across the entire species elevation range, namely, the leaf mass fraction decreased continuously, whereas the flower mass fraction and the root:shoot ratio increased steadily from the lowest to the highest elevations. Observed variations in S. carpatica phenotypes are seen as structural adjustments to environmental changes across elevations that increase chances of plant survival and reproduction at different elevations. Moreover, results of the present study agreed with the observations that populations of species from the ‘Soldanella’ intrageneric group adapted to alpine and subnival zones still maintain typical ‘Soldanella’-like appearance, despite considerable reduction in overall plant size.

A Full Accounting of the Visible Mass in SDSS MaNGA Disk Galaxies

We present a study of the ratio of visible mass to total mass in spiral galaxies to better understand the relative amount of dark matter present in galaxies of different masses and evolutionary stages. Using the velocities of the Hα emission line measured in spectroscopic observations from the Sloan Digital Sky Survey (SDSS) MaNGA Data Release 17 (DR 17), we evaluate the rotational velocity of over 5500 disk galaxies at their 90% elliptical Petrosian radii, R 90. We compare this to the velocity expected from the total visible mass, which we compute from the stellar, H i, H2, and heavy metals and dust masses. H2 mass measurements are available for only a small subset of galaxies observed in SDSS MaNGA DR17, so we derive a parameterization of the H2 mass as a function of absolute magnitude in the r band using galaxies observed as part of SDSS DR7. With these parameterizations, we calculate the fraction of visible mass within R 90 that corresponds to the observed velocity. Based on statistically analyzing the likelihood of this fraction, we conclude that the null hypothesis (no dark matter) cannot be excluded at a confidence level better than 95% within the visible extent of the disk galaxies. We also find that when all mass components are included, the ratio of visible to total mass within the visible extent of star-forming disk galaxies increases with galaxy luminosity.

Effect of calcium treatment on evolution of inclusions in low-carbon aluminum-killed steel

Based on the steel samples collected from low carbon aluminum-killed steel at ladle furnace start, end of ladle furnace heating, ladle furnace end and tundish pouring process for inclusions analysis, the influence of calcium treatment on the evolution of inclusions in steel from ladle furnace refining to continuous casting was investigated under the condition of using Al2O3-lining ladle. The results show that when calcium treatment is not used, the inclusions in steel are mainly Al2O3 and MgO-Al2O3 spinel, and the mass fraction of Al2O3 in the inclusions composition is ≥90% from ladle furnace refining to continuous casting. After calcium treatment is carried out, the types of inclusions in steel are mainly MgO-Al2O3-CaS (-CaO) inclusions, in which the content of Al2O3 and CaS is higher than the samples without calcium treatment, and low-melting point calcium-aluminate inclusions were not found in the samples. The average size of inclusions in the steel was similar for both processes during ladle furnace refining, but the number density of inclusions in the steel increased significantly after calcium treatment. At the end of LF, the number density of inclusions in the calcium-treated is about twice that of the non-calcium-treated.

Implementation of thorium-based fuel for Indonesia Micro Reactor (IMR)

Indonesia has committed to reducing greenhouse gas emissions in the framework of net zero emissions, and nuclear energy will be a part of the energy mix. Indonesia has been developing a 10 MWt micro reactor of high temperature gas-cooled reactor (HTGR) with pebble fuel containing 17 % enriched UO2 kernel with OTTO cycle scheme. For the government’s interest to use thorium, this paper assesses the possibility of replacing uranium with thorium. The assessment is performed by calculating the effective neutron multiplication factor (keff). Neutrons captured by 232Th lead to the formation of two intermediate isotopes, namely 233Th and 233Pa, the latter being a significant neutron absorption cross-section. Neutronics analysis is performed using parameters of thorium mass fraction, core temperature, and active core height. The thorium mass fractions varies from 0 % to 90 % Th. The core temperatures are in the range of the normal operating temperature at 900 K, assumed superheat temperature at 1200 K, and shutdown temperature at 300 K. The active core height varies at 197, 180, 150, 130, and 125 cm. This paper aims to determine the keff of the IMR at maximum thorium/uranium mass fraction composition, maximum active core height, core temperature, and fuel burn-up. The MCNP code is used for analysis. The results show that keff decreases with increasing thorium mass fraction and core temperature, and decreasing active core height. Calculations with thorium mass fraction of 15 %, core active height of 197 cm in 20 steps show that the reactor may be continuously operated for more than 920 days without refueling. The analysis results show that IMR design has negative temperature reactivity, inherent safety characteristics, and the ability to use thorium-based fuels.

Searching for OB-type pre-supernova binary companions inside supernova remnants

Abstract We searched for OB-runaway stars inside supernova remnants (SNRs) as a pre-supernova binary companion. As the majority of massive stars are found in close binary systems, a runaway star ejected by the orbital energy after the supernova (SN) is expected to be found. Considering a binary mass fraction, q=0.25 − 1.0, the runaway star is likely to have an OB spectral type. We selected 12 SNRs at Galactic longitudes 109○ − 189○. Using Gaia astrometry we selected stars having consistent distances with those of the SNRs and showing a peculiar proper motion directed away from the central region of the SNRs. We also determined the radial distribution of the extinction towards the SNRs and estimated the spectral types of the OB-runaway candidates through Gaia and 2MASS photometry. We found two candidates among 12 SNRs. By spectroscopic observations, Gaia DR3 195632152560621440 inside SNR G166.0+4.3 was found to be an evolved A3 type star which cannot be the pre-SN binary companion to the progenitor. Gaia DR3 513927750767375872 inside SNR HB 3 is the only OB-runaway candidate (2-D space velocity of 33.3±3.3 km s−1). Based on photometric study, the star can be an early B-type main sequence star with a slightly higher extinction relative to the SNR, however, it might instead be an evolved A-type star at the same distance. The other 11 SNRs do not host an OB-runaway star within their central regions. Although the runaway search was performed in a large interval of distance and extinction, we also estimated distances to the SNRs.

Guanidine Hydrochloride-Induced Hepatitis B Virus Capsid Disassembly Hysteresis.

Hepatitis B virus (HBV) displays remarkable self-assembly capabilities that interest the scientific community and biotechnological industries as HBV is leading to an annual mortality of up to 1 million people worldwide (especially in Africa and Southeast Asia). When the ionic strength is increased, hepatitis B virus-like particles (VLPs) can assemble from dimers of the first 149 residues of the HBV capsid protein core assembly domain (Cp149). Using solution small-angle X-ray scattering, we investigated the disassembly of the VLPs by titrating guanidine hydrochloride (GuHCl). Measurements were performed with and without 1 M NaCl, added either before or after titrating GuHCl. Fitting the scattering curves to a linear combination of atomic models of Cp149 dimer (the subunit) and T = 3 and T = 4 icosahedral capsids revealed the mass fraction of the dimer in each structure in all the titration points. Based on the mass fractions, the variation in the dimer-dimer association standard free energy was calculated as a function of added GuHCl, showing a linear relation between the interaction strength and GuHCl concentration. Using the data, we estimated the energy barriers for assembly and disassembly and the critical nucleus size for all of the assembly reactions. Extrapolating the standard free energy to [GuHCl] = 0 showed an evident hysteresis in the assembly process, manifested by differences in the dimer-dimer association standard free energy obtained for the disassembly reactions compared with the equivalent assembly reactions. Similar hysteresis was observed in the energy barriers for assembly and disassembly and the critical nucleus size. The results suggest that above 1.5 M, GuHCl disassembled the capsids by attaching to the protein and adding steric repulsion, thereby weakening the hydrophobic attraction.

Thermodiffusion, diffusion and Soret coefficients of binary polymeric mixtures in toluene and cyclohexane

Abstract We present the results of experimental study on measuring the thermodiffusion, molecular diffusion and Soret coefficients of polystyrene (4,880 g/mol) in the pure solvents toluene and cyclohexane at 298 K and atmospheric pressure. The experiments have been carried out for a wide range of concentrations, starting from the diluted state with 2 % polystyrene mass fraction (proposed in the DCMIX4 project) up to the semidilute regime of 20 % polystyrene mass fraction. In addition, we present a complete characterisation of the thermophysical properties of the analysed mixtures. Thermodiffusion, molecular diffusion and Soret coefficients of binary polymeric samples have been measured by combining the traditional thermogravitational column technique, the thermogravitational microcolumn and the optical beam deflection method. In toluene, the obtained experimental results are consistent with literature, showing that the magnitude of the mass transport thermoproperties decrease significantly with increasing polystyrene concentration, which is a first indication of an approaching glass transition in the concentrated regime. The results for thermodiffusion and molecular diffusion coefficients in cyclohexane as a function of concentration exhibit a similar trend. Nevertheless, the Soret coefficient seems to show an opposite tendency for the two solvents, increasing in magnitude for cyclohexane, at least up to the analysed polystyrene concentration.

INSPIRE: INvestigating Stellar Population In RElics VI - The low-mass end slope of the stellar Initial Mass Function and chemical composition

Abstract The INSPIRE project has built the largest sample of ultra-compact massive galaxies (UCMGs) at 0.1 < z < 0.4 and obtained their star formation histories (SFHs). Due to their preserved very old stellar populations, relics are the perfect systems to constrain the earliest epochs of mass assembly in the Universe and the formation of massive early-type galaxies. The goal of this work is to investigate whether a correlation exists between the degree of relicness (DoR), quantifying the fraction of stellar mass formed at z > 2, and the other stellar population parameters. We use the Full-Index-Fitting method to fit the INSPIRE spectra to single stellar population (SSP) models. This allows us to measure, for the first time, the slope of the IMF, as well as stellar metallicity [M/H], [Mg/Fe], [Ti/Fe] and [Na/Fe] ratios, and study correlations between them and the DoR. Similarly to normal-sized galaxies, UCMGs with larger stellar masses have overall higher metallicities. We found a correlation between the IMF slope and the DoR, that, however, breaks down for systems with a more extended SFH. An even stronger dependency is found between the IMF and the fraction of mass formed at high-z. At equal velocity dispersion and metallicity, galaxies with a higher DoR have a larger dwarf-to-giant ratio, i.e. a bottom heavy IMF, than that of low-DoR counterparts. This might indicate that the cosmic epoch and therefore different formation scenarios influence the fragmentation of the star formation cloud and hence might be the explanation for IMF variations detected in massive ETGs.

Analytical assessment of hetero-/homogeneous combustion of magnesium particle: Fully explicit formulas for flame characteristics

In this study, by proposing a comprehensive multi-step model, the combustion of magnesium particles in O2-He, O2-Ar, and O2-N2 is scrutinized. In the current model, both the heterogeneous and homogeneous combustions are considered and the process is divided into four stages solid, liquid, and gas combustion and melting. Moreover, the diffusions of oxygen and unreacted magnesium to droplet and infinity together with surface exothermic reaction are considered. The governing equations are analytically solved and then, the formulas are extracted for combustion time and temperature, flame standoff distance, and evaporation rate as the functions of particle diameter, ambient temperature and pressure, oxygen mass fraction, type of inert gas, and Lewis numbers. For 120 µm particle and oxygen content of 0.05, time contributions of homogeneous and heterogeneous combustions are 85.8% and 14.2%, respectively. The burning time has drastic changes at ambient pressures below l atm, so that the burning time variations relative to the pressure in the environments less than 1 atm and greater than it are equal to 1200–1550 and 70–90 ms/atm, respectively. When the oxygen mass fraction is less than 0.29, combustion in helium-oxygen ends earlier than that in O2-Ar and O2-N2, but for the mass fraction greater than 0.35, it has the longest burning time.

Study of New CGSP‐P Series Phosphate Matrix Reference Materials for LA‐ICP‐MS

A series of three CGSP‐P phosphate matrix reference materials, with variable element mass fractions, were synthesised by co‐precipitation with CaCl2 and (NH4)3PO4 to form a hydroxylapatite matrix. Each powder sample was packaged into multiple bottles and pressed into tablets as replicates. The within‐bottle homogeneity was evaluated by the repeatability of element mass fractions of six spots in per tablet of CGSP‐Ps by LA‐ICP‐MS. For the between‐bottle homogeneity evaluation, one approach adopted the % RSD of element mass fractions in twelve different tablets from twelve bottles in the same reference material in comparison with the repeatability field of LA‐ICP‐MS analyses obtained from homogeneous glasses, and the other used a one‐way analysis of variance (ANOVA) approach. Most of the elements (e.g., Mg, Ca, P, Mn and REE) were homogenous within 10% RSD, and other elements (e.g., Si, Al, K, Rb, Cs and Ni) were considered heterogeneous (with > 20% RSD). All of the elements passed the t‐test except Ni in CGSP‐P3, and V, Cr, Ni, Zr, Gd, Dy and Th in CGSP‐P4 after a 29‐month period stability examination by LA‐ICP‐MS. The preliminary reference values and standard uncertainties for CGSP‐Ps are given with a network of methods and eight laboratories by bulk analysis according to ISO Guide 35:2006 and JJF 1343‐2012.

Thermodynamic descriptions of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems over the whole composition and temperature ranges

AbstractThe CaO–Al2O3–SiO2 system is a fundamental system in aluminosilicate materials, and its thermodynamic description provides key information for ceramic design, cement production, slag tapping, and geological prediction. However, the existing thermodynamic calculations for the CaO–Al2O3 system show inaccurate heats of formation for the compounds and consequently a decomposition of the CA2 (CaO⋅2Al2O3) phase at a low temperature. Besides, the solid solutions in anorthite and cristobalite have never been considered in the previous thermodynamic assessments for the CaO–Al2O3–SiO2 system. Therefore, thermodynamic reassessments of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems are carried out in the present work using the CALculation of PHAse Diagram method, considering the solid solution in anorthite and cristobalite for the first time. The anorthite and cristobalite phases are modeled based on the individual mechanism of solid solution, with the anorthite described by (Ca+2, Va)1(Al+3, Si+4)2(Si+4)2(O−2)8 and the cristobalite described by (Va, Ca+2)1(Si+4, Al+3)2(O−2)4. The present assessment solves the above issues and provides consistent thermodynamic descriptions for the liquid and solid phases. Based on the established thermodynamic database, a Scheil solidification simulation is carried out for a cement clinker and the variations of mass fractions of the phases as well as the composition of liquid during Scheil cooling are calculated. The present work guides the design of relevant materials and lays an essential foundation for the establishment of the thermodynamic database of multicomponent aluminosilicate materials.

Chemical evolution of the Galactic bulge with different stellar populations

The metallicity distribution function (MDF) of the Galactic bulge is characterized by a multi-peak shape, with a metal-poor peak centered at $ Fe/H sim-0.3 $ dex and a metal-rich peak centered at $ Fe/H sim+0.3 $ dex. The bimodality of the MDF is also reflected in the alpha /Fe versus Fe/H abundance ratios, suggesting the presence of different stellar populations in the bulge. In this work we aim to reproduce the observed MDF of the Galactic bulge by testing a scenario in which the metal-poor component of the bulge is formed by stars formed in situ, during a strong burst of star formation, while the metal-rich population is formed by stars created in situ during a second burst of star formation and/or stars accreted from the innermost part of the Galactic disk as an effect of a growing bar. We adopted a chemical evolution model that is able to follow the evolution of several chemical species with detailed nucleosynthesis prescriptions. In particular, because of the importance of the production of Fe in constraining the MDF, close attention is paid to the production of this element in both Type Ia supernovae and massive stars. In particular, we included yields from rotating massive stars with different rotational velocity prescriptions. Our model also takes the infall and outflow of gas into account, as well as the effect of stellar migration. Results are compared to sim 13000 stars from the SDSS/APOGEE survey that belong to the region located at a Galactocentric distance $ R_ GC kpc We successfully reproduce the observed double-peak shape of the bulge MDF as well as the abundance trends of the alpha elements relative to Fe by assuming both (i) a multi-burst star formation history with a quenching of the first burst of $ 10^2\ Myr $ and (ii) migration of stars from the innermost part of the Milky Way disk, as an effect of a growing bar. According to our results, the fraction of the stellar mass of the bulge-bar that belongs to the inner disk is $ sim40<!PCT!> $. In terms of the nucleosynthesis, we conclude that models that assume either no rotation for massive stars or a distribution of rotational velocities that favors slow rotation at high metallicities best reproduce the observed MDF as well as the alpha /Fe and the Ce/Fe versus Fe/H abundance patterns.

A Combustion Kinetic Model Based on the Fast Chemistry Assumption: Application to Non-Sooty and Sooty Laminar Diffusion Flames

ABSTRACT In this article, a combustion kinetic model based on the fast chemistry (FC) assumption is proposed to compute the finite reaction rate of gaseous species in laminar diffusion flames. The algorithm developed for this purpose is numerically robust and relies on the adiabatic flame temperature to limit the fuel consumption rate. While there is no FC model specifically developed for laminar flames, the Eddy Dissipation Model (EDM) correction scheme for laminar regimes is taken as the reference model. The proposed model addresses the shortcomings of the reference model, i.e. the sensitivity to the transport time scale and the cell size and the need to calibrate a numerical constant repeatedly. The new model formulation does not rely on any numerical constant and completely removes the dependency on the cell size and the species transport time scale, as shown for multiple counterflow and axisymmetric laminar diffusion flames. Furthermore, the proposed model provides consistent temperature and species mass fraction predictions across the mentioned flames. Finally, a sooty axisymmetric flame is simulated using the mentioned models to investigate the numerical interaction between combustion and soot chemistry. The results show that the reference model requires recalibration to capture the temperature and soot volume fraction distributions while the proposed model yields reasonably accurate temperature and soot predictions.

Study on the corrosion behaviour of carbon nanotubes/graphene/WPU coated steel

AbstractThe bond strength, resistivity and corrosion resistance of Q235 steel coated with composites containing various concentrations of carbon nanotubes, graphene and waterborne polyurethane (CNTs/Gr/WPU) were evaluated in a 5% NaCl solution. Additionally, the galvanic corrosion between the coated steel and galvanised steel was investigated through galvanic potential, galvanic current, corrosion morphology and corrosion rate. The results show that the CNTs/Gr/WPU‐coated steel exhibits excellent adhesion and conductivity. Moreover, the incorporation of CNTs and Gr can effectively enhance the corrosion resistance of the CNTs/Gr/WPU‐coated steels in the 5% NaCl solution. The trends of the galvanic potentials and galvanic current densities of CNTs/Gr/WPU‐coated steel with different mass fractions coupled with galvanised steel are similar. The CNTs/Gr/WPU‐coated steels exhibit severe galvanic corrosion when coupled with galvanised steel.

Indonesian experience in providing accuracy-based proficiency testing scheme using metrologically traceable reference values for elements mass fraction in drinking water

Indonesian experience in providing accuracy-based proficiency testing scheme using metrologically traceable reference values for elements mass fraction in drinking water

Free vibration analysis of a sandwich conical shell with a magnetorheological elastomer core, enriched with carbone nanotubes and functionally graded porous face layers

In this paper, the free vibration behaviors of a sandwich conical shell with a magnetorheological elastomer (MRE) core enriched with carbon nanotubes (CNTs) and two functionally graded (FG) porous face layers are investigated. The mathematical modeling of the shell is performed via the first-order shear deformation theory (FSDT) incorporating the continuity conditions between the face layers and the core. The porosity parameters are adjusted to provide the same mass for all porosity dispersion patterns. The governing equations and boundary conditions are derived via Hamilton’s principle and are solved through a semi-analytical solution to attain the natural frequencies and the loss factors for various boundary conditions. First, appropriate triangular functions are utilized to provide an exact solution in the circumferential direction. Then, a numerical solution is presented in the meridional direction utilizing the differential quadrature method (DQM). The influences of various factors on the natural frequencies and loss factors are investigated including intensity of the applied magnetic field, mass fraction of the CNTs subjoined to the core, thickness of the CNT-reinforced MRE core, thickness of the FG porous face layers, porosity parameter and dispersion pattern of the pores in the FG porous face layers, and the boundary conditions. Numerical results show that although subjoining CNTs to the MRE core and applying magnetic field have weak effects on the natural frequencies of the shell, increases in the mass fraction of the CNTs and intensity of the applied magnetic field result in remarkable increases in the loss factors, and provide stronger vibration suppression.