Ultrasound and microwave assisted extraction of diosgenin from fenugreek seed and fenugreek-supplemented cookies

Fenugreek has been recognized as the most important medicinal plant. The presence of diosgenin in fenugreek seed is known to have promising health benefits. In the present work the extraction of diosgenin from the fenugreek seed was performed and its supplementation in cookies was done. The ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods have been applied for extraction of diosgenin. In case of UAE, the maximum diosgenin was obtained from fenugreek seed powder with 80 % ethanol solution for 50 min, whereas the maximum diosgenin in MAE was obtained at 80 % ethanol solution for 4 min. Overall, the extract yield of UAE was higher than MAE. The UAE method with an ethanolic concentration of 80 % was considered as optimum for the determination of diosgenin in cookies. The diosgenin content of the cookies supplemented with fenugreek seed powder increased with its increase and the diosgenin content ranged from 0.099 to 0.191 g diosgenin equivalent/100 g of cookies. Further research on the incorporation of fenugreek seed powder and diosgenin in ready-to-eat foods are of great value because of health benefits of diosgenin and market demand of ready-to-eat foods.     

Statistical analysis on results of optimal power sharing between linked microgrids

The future distribution network will be made of interconnected distribution systems, so-called microgrids (MGs). MGs provide an effective means of utilising energy from small-scale renewable resources. The probabilistic power generation behaviour renewable generations and load forecasting errors are the most important uncertainties in the MG operation. The proposed methodology of this paper applies these uncertainties into the operation problem in order to find the practical solutions. So, in this research the economic operation of multi-MGs is formulated as a cost-based objective function which is minimised using particle swarm optimisation algorithm. As a result, the problem outputs must be defined by probability distribution functions (PDFs) in order to achieve comprehensive analysis of the literature. Another contribution of the paper, which rises the accuracy of the analysis in operation discussion, is applying suitable fitting criteria to select the best PDF for each obtained result based on Akaike's information criterion.     

Parametric study on the performance of the earth‐to‐air heat exchanger for cooling and heating applications

To reduce energy consumption, the earth‐to‐air heat exchanger (EAHE) is a suitable technique for cooling and heating buildings. This paper studies numerically the effect of some design parameters (pipe diameter, inlet condition, pipe length, and outlet condition) on the overall performance of the EAHE system. Four diameters of the EAHE pipe (2, 3, 4, and 6 in) are studied and this numerical study has been done for summer and winter seasons for Nasiriyah city in southern Iraq. First, the built numerical model was validated against the experimental model, and the results of comparison showed a good consensus. After the validation and by using computational fluid dynamics modeling, the overall performance of the EAHE system with all pipe diameters was analyzed with ranges of air velocity, DBT or inlet temperature, and a pipe length of 50 m. The simulated results showed that the EAHE system with 6 in pipe diameter has the best values of overall performance, but from the thermal performance point of view, the 2 in pipe diameter is more suitable.     

Generalized differential quadrature nonlinear buckling analysis of smart SMA/FG laminated beam resting on nonlinear elastic medium under thermal loading

The nonlinear thermal buckling analysis of functionally graded (FG) beam integrated with shape memory alloy (SMA) layer(s), with different lay-up configurations and supported on a nonlinear elastic foundation, has been investigated. The FG layer is graded through the beam thickness direction and thermomechanical properties are assumed to be temperature dependent. The Brinson one-dimensional constitutive law are used to model the characteristics of SMA. The von Kármán strain–displacement fields with the Timoshenko beam theory are applied to the Hamilton’s principle to derive the set of nonlinear equilibrium equations. Generalized differential quadrature method along with direct iterative scheme is utilized to discretize and solve the nonlinear equilibrium equations. The accuracy of proposed model is compared and validated with previous research in literature. The detailed parametric study has been performed to investigate the influence of geometrical, material, and some other key parameters on the nonlinear thermal buckling solutions. The results show that selecting the proper lay-up is of great importance because the type of SMA/FG lay-up can considerably affect the nonlinear buckling solutions. Moreover, adequate application of SMA layers in a proper lay-up configuration significantly postpones the thermal buckling temperature of the beam.     

Effects of the porous medium and water-silver biological nanofluid on the performance of a newly designed heat sink by using first and second laws of thermodynamics

The aim of this numerical investigation is to evaluate the laminar forced convection of biologically synthesized water-silver nanofluid through a heat sink (HS) filled with porous foam (PHS) using first and second laws of thermodynamics. The impacts of inlet velocity (V=0.5-3 m·s^-1) and volume fraction of nanofluid (φ=0-1%) on the performance metrics of HS are assessed and the outcomes are compared with those of the non-porous HS (NHS). The outcomes revealed that for both the PHS and NHS, the increase of V causes an intensification in convection coefficient, pumping power, and entropy generation due to fluid friction, while the maximum CPU temperature, thermal resistance, and entropy generation due to the heat transfer reduces by boosting V. Also, it was found that the augmentation of V results in intensification in convection coefficient, pumping power, overall hydrothermal performance, and frictional entropy generation, while the opposite is true for maximum CPU temperature, thermal resistance, and thermal entropy generation. Furthermore, it was reported that, except for φ=0.5%, the overall hydrothermal performance of NHS is better than that of PHS, while PHS has better second-law performance than NHS in all the studied cases. Also, it can be concluded that the best hydrothermal performance for PHS belongs to φ= 1% and V=0.5 m·s^-1, while for NHS, these values are 1% and 2 m·s^-1.     

Molecular laser isotope separation versus atomic vapor laser isotope separation

In this work, the competitive molecular and atomic laser isotope separation methods are investigated to evaluate the potential of each une for more economical fuel fabrication of enriched uranium celas which can be practically used in light water reactors (LWR). The advantages, drawbacks and feasibility of various techniques of laser isotope separation including AVLIS and the main MLIS methods such as MOLIS, CRISLA, and SILARC techniques have been reviewed. Laser isotope separation (LIS) deserves an intensive research, because laser techniques have a number of advantages over traditional ones, such as highly selective elementary separation event, possibility of separating the required isotope, low energy consumption, short start up time and practically single-stage production, which may economize fuel processing [11.     

Design of a Dynamic ADC Comparator with Low Power and Low Delay Time for IoT Application

Wireless Personal Communications - In this paper, a low power and low delay comparator circuit for the IoT applications has been designed and analyzed. In the proposed comparator, two different...     

Semi-active fuzzy control of Lali Cable-Stayed Bridge using MR dampers under seismic excitation

Seismic control of cable-stayed bridges is of paramount importance due to their complex dynamic behavior, high flexibility, and low structural damping. In the present study, several semi-active Fuzzy Control Algorithms (FCAs) for vibration mitigation of Lali Cable-Stayed Bridge are devised. To demonstrate the efficiency of the algorithms, a comprehensive nonlinear 3-D model of the bridge is created using OpenSees. An efficient method for connecting MATLAB and OpenSees is devised for applying FCAs to the structural model of the bridge. Two innovative fuzzy rule-bases are introduced. A total of six different fuzzy rule-bases are utilized. The efficiency of the FCAs is evaluated in a comparative manner. The performance of fuzzy control systems is also compared with a sky-hook and a passive-on system. Moreover, the sensitivity of efficiency of control systems to the peak ground acceleration is evaluated qualitatively. In addition, the effect of time lag is also investigated. This study thoroughly examines the efficiency of the FCAs in different aspects. Therefore, the results can be regarded as a general guide to design semi-active fuzzy control systems for vibration mitigation of cable-stayed bridges.     

Chemically Modified CaO/Fe3O4 Nanocomposite by Sodium Dodecyl Sulfate for Cr(III) Removal from Water

A CaO/Fe₃O₄ nanocomposite was modified by sodium dodecyl sulfate (SDS) and used for Cr(III) removal from aqueous solution. The physical and surface characteristics of the adsorbent were studied by different analysis techniques. The effects of key parameters such as pH, contact time, temperature, initial concentration of Cr(III) ions, and adsorbent dose were investigated at a fixed mixing rate. Parameters were optimized to attain the best possible removal efficiency of Cr(III) ions. The maximum adsorption capacities obtained from the Langmuir model were determined. The results of equilibrium and kinetic studies indicate that the adsorption process follows the Langmuir isotherm model and the pseudo‐second‐order kinetic model. The thermodynamic study demonstrated that the adsorption process was suitable, spontaneous, and exothermic.     

A bridge technique for memristor state programming

ABSTRACT

In order to effectively use a memristor in analog circuits, its memristance should be adjusted to a desired value between its limits. Since the maximum and minimum required memristance typically varies considerably between different types of memristors, it is almost impossible to tune the resistance of each memristor based on a reference resistor. Which is mostly done using some programmer circuits. Moreover, those programming strategies involving pulses are time-consuming and they impose high hardware headroom. In this paper, a novel CMOS circuit is presented for programming memristors. A Wheatstone bridge circuit is used to measure the current memristance, while the programming current is flowing through the device. Using such an approach reading the state and its adjustment are done simultaneously, which reduces the programming latency. In the proposed method, instead of tuning the memristance, the state of the memristor will be set to the desired value, which is proportional to a control voltage. The low programming latency, six-bit accuracy, and use of a simple circuit for programming, are the main advantages of our solution. The proposed circuit is designed and laid out in 0.35 µm CMOS technology and takes 0.0273mm². Furthermore, the proposed approach is applied to a memristor emulator to demonstrate its correct operation in real applications.