Search

In this paper, phase transition temperatures of nematic liquid crystals: 4-n alkoxy benzoic acid (nOBA, where n = 4 and 6) are determined from the Legendre moments of liquid crystal textures. Here, the image analysis technique in conjunction with polarizing optical microscope is used to compute the Legendre moments from the textures of liquid crystals. As a function of temperature, Liquid crystal textures are recorded from the arthroscopic mode of optical microscope. Changes in textural features of the sample with respect to temperature bring the variations in intensity values of liquid crystal textures. The brightness image that is generated from the liquid crystal textural patterns separates the information about fluctuations in intensity. In this approach, Legendre moments are computed from the brightness images of the liquid crystal textures and are plotted as a function of temperature. Significant variations in the brightness Legendre moment curve provide insight into the liquid crystal transition temperatures. Results obtained from the present methodology are compared with gray color textures data and the experimental technique of differential scanning calorimetry and are in good agreement with each other. This method is an objective and quantitative technique whereas POM method is qualitative and subjective. [ABSTRACT FROM AUTHOR]

The flow of fluids containing nanoparticles is important in industrial applications, particularly in nuclear reactors and nuclear system cooling to enhance energy efficiency. In connection to this, the convective boundary layer flow of ternary hybrid nanofluid (water-based graphene-CNT-Silver) flow over a curved stretching sheet with activation energy is investigated in this article. In addition, the non-Fourier heat flux model is taken into account. The use of similarity variables transforms the existing partial differential equations into an ordinary differential equation, which is then numerically solved using the Runge-Kutta-Fehlberg fourth and fifth order (RKF-45) method combined with a shooting approach. The set of graphical results for the significant parameters on thermal, concentration, and velocity profiles is explored. Results reveal that the heat transport in ternary hybrid nanoliquid rises as the thermophoresis and Brownian motion parameters rise. The Biot number influences the thermal profile positively, whereas the increasing Schmidt number and Stefan blowing parameter values reduce mass transport. The curvature parameter has positive impact on skin friction and mass transport rate but negative impact on heat transport rate. The concentration profile rises with increased activation energy parameter, but declines with increased chemical reaction rate parameter.

This paper presents an innovative approach to achieve efficient solar water pumping through the integration of a Photovoltaic (PV) array and a Brushless Direct Current (BLDC) motor water pumping system. The system incorporates a Voltage Source Converter (VSC) with six switches, utilized to facilitate commutation. The inherent solar radiation is harnessed by the PV array, capitalizing on its renewable nature to generate electricity. By dynamically adjusting the switching states of the six VSC switches, the speed of the BLDC motor is modulated in response to the varying levels of available solar radiation. The BLDC motor's hall sensor signals play a crucial for determining the rotor's position and they are employed to generate precise commutation signals. The control strategy integrates the Incremental Conductance (INC) Maximum Power Point Tracking (MPPT) algorithm, which initially governs the commutation signals. To enhance adaptability to rapidly changing solar irradiation conditions, the control strategy dynamically updates the commutation signals using the innovative Beta MPPT algorithm. To assess the efficiency of the proposed control strategy, a comprehensive comparison between the INC and Beta MPPT algorithms is conducted using MATLAB Simulink. The performance of the BLDC motor under these algorithms was evaluated in terms of its ability to optimize energy extraction. The graphical analysis of these algorithms, considering the temporal aspect, substantiates the identification of the superior MPPT algorithm for BLDC motor control in solar water pumping applications. This study contributes to the advancement of solar water pumping systems by introducing a novel control approach that combines PV array utilization, VSC-based commutation, and a dual-step MPPT algorithm. The results demonstrate the effectiveness of the Beta MPPT algorithm by enabling the system to respond promptly to fluctuating solar irradiation conditions, thereby enhancing the overall efficiency of the solar water pumping process. [ABSTRACT FROM AUTHOR]

Multifunctional aromatic linker ligands are crucial for designing robust heterogeneous electrocatalytic systems with an effective surface distribution of atomic redox active sites. Herein, we report the chemical immobilization of hetero‐metal ions (Fe and Cu) containing metallopolymers on copper surface as a low overpotential and stable electrocatalyst in acidic electrolyte. The sulfur and nitrogen‐rich triazine trithiolate ligand enables the active sites atomistic distribution through coordination linkage and displays an impressive low overpotential of −94 mV vs. RHE to attain −10 mA cm−2 in 0.5 M H2SO4. It is almost 103 times higher hydrogen evolution current densities than the copper substrate. The increased iron content and activation in acidic electrolyte reduce the overpotential and increase the electrochemical active surface area and catalytic activity. The long‐term hydrogen evolution suggests excellent stability in strong acidic electrolytes, and the film remains adherent to the substrate at higher hydrogen evolution current densities of −500 mA cm−2 and −700 A gm−1. [ABSTRACT FROM AUTHOR]

Hybrid microgrids run by renewable energy sources are gaining popularity around the world. Solar (PV) and permanent magnet synchronous generator (PMSG) based wind energy systems (WES) are well-known and easy to install renewable energy options. Unfortunately, wind speeds and solar irradiance levels fluctuate unpredictably. Energy generation from both WES and PV panels must therefore fluctuate. Simultaneously, the load is fluctuating irregularly. Hence, storage devices must be incorporated into hybrid systems in order to keep the generation and consumption of electricity in equilibrium. In addition, for a fuel cell and electrolyzer that run on hydrogen, a tiny battery is added into the system to keep costs down. In order to enhance power quality and reliability, all the components in a microgrid need to be connected to an effective energy management system. For optimal use, renewable energy sources are combined with maximum power point trackers. When there are sudden shifts in both the energy supply and demand on a standalone microgrid, the energy balance and frequency response are crucial. In this study, a Takagi Sugeno based innovative fuzzy controller is implemented for a system to manage energy in order to achieve a precious and rapid reaction. The suggested system's Hardware-In-the-Loop is built using OPAL-RT modules in order to demonstrate detailed findings. [ABSTRACT FROM AUTHOR]

In the current work, in the presence of a heat source and temperature gradients, the onset of triple-diffusive convective stability is studied for a fluid, and a fluid-saturated porous layer confined vertically by adiabatic limits for the Darcy model is thoroughly analyzed. With consistent heat sources in both layers, this composite layer is subjected to three temperature profiles with Marangoni effects. The fluid-saturated porous region's lower boundary is a rigid surface, while the fluid region's upper boundary is a free surface. For the system of ordinary differential equations, the thermal surface-tension-driven (Marangoni) number, which also happens to be the Eigenvalue, is solved in closed form. The three different temperature profiles are investigated, the thermal surface-tension-driven (Marangoni) numbers are calculated analytically, and the effects of the heat source/sink are studied in terms of corrected internal Rayleigh numbers. Graphs are used to show how different parameters have an impact on the onset of triple-diffusive convection. The study's parameters have a greater influence on porous layer dominant composite layer systems than on fluid layer dominant composite layer systems. Finally, porous parameters and corrected internal Rayleigh numbers are stabilize the system, and solute1 Marangoni number and ratio of solute2 diffusivity to thermal diffusivity of fluid are destabilize the system. [ABSTRACT FROM AUTHOR]

Background During pregnancy, iron is transferred from mother to fetus with placental iron transport proteins (Transferrin receptor, Divalent metal transporter/DMT1, ferroportin/FPN1 and Zyklopen). The aim of the study was to evaluate the effect of maternal iron deficiency anemia on placental iron transporters. Study Design: Two hundred pregnant women, in third trimester of pregnancy were divided into anemic (Hemoglobin/Hb < 11g/dl) and non-anemic groups (Hb ≥ 11 g/dl). After delivery, placental expression of iron transport proteins were studied by immunohistochemistry and by mRNA analysis. Results: Of the 200 subjects, 59% were anemic. All 3 placental proteins showed statistically significant increase in immunohistochemical expression, proportionate to the severity of maternal anemia. The mRNA expression of DMT-1 gene was only significantly elevated in placentas of anemic mothers. Conclusion: Although in our study mRNA expression of only the DMT-1 gene was significantly high, immunohistochemically however all the 3 proteins showed significantly higher expression in placentas of anemic mothers. [ABSTRACT FROM AUTHOR]

Searching for the critical slip surface and the lowest factor of safety in slope stability analysis can be achieved by means of optimization techniques. A new search procedure in generating kinematically admissible slip surfaces has been introduced in this paper. Such a procedure is based, mainly, on the Monte Carlo methods, where both the critical global slip surface as well as its associated factor of safety is determined. Several practical examples, of known minimum factor of safety and its associated slip surface, have been used to demonstrate the efficiency and capability of the proposed method. The method is intended to be robust and effective to solve problems that involve extremely complicated slope geometry. It is as powerful as any other powerful optimization methods.