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The objective of this research was to evaluate the impact of the morphology of SiC additive on the microstructure development, sintering behavior, hardness, and fracture toughness of TiB 2 -based ceramics. For this purpose, three different samples were produced via the hot-pressing method at 1950 °C under 25 MPa for 120 min. Subsequently, the samples were characterized by XRD, SEM, and optical microscopy. The samples containing SiC particles (SiC p) reached their theoretical densities. XRD results manifested the formation of an in-situ TiC during the hot-pressing. Thermodynamical investigation and SEM fractographs revealed the role of a liquid phase in boosting the sintering behavior of as-sintered ceramics. The SEM images also confirmed the in-situ generation of B 4 C in the specimens doped with SiC whiskers (SiC w). Finally, the most significant Vickers hardness (28.9 GPa) and fracture toughness (6.4 MPa m1/2) was secured for the sample toughened by 30 vol% SiC w , whereas the lowest values, namely a Vickers hardness of 18.1 GPa and a fracture toughness of 5.1 MPa m1/2, were obtained for the composites doped with 30 vol% SiC p , and 15 vol% SiC w + 15 vol% SiC p , respectively. [ABSTRACT FROM AUTHOR]

This investigation intended to assess the influence of SiC morphology on the sinterability and physical-mechanical features of TiB 2 -SiC composites. For this aim, different volume percentages of SiC particles and SiC whiskers were introduced to TiB 2 samples hot-pressed at 1950 °C for 2 h under an external pressure of 25 MPa. The characterization of as-sintered specimens was carried out using X-ray diffraction, optical microscopy, and scanning electron microscopy. The relative density studies revealed that SiC w had a more significant impact on the sinterability of TiB 2 -based composites. The XRD investigation confirmed the production of an in-situ TiC phase during the hot-pressing; however, some peaks related to the graphitized carbon also appeared in the patterns of SiC w -doped ceramics. The addition of 25 vol% SiC p halved the average grain size of TiB 2 while introducing the same content of SiC w decreased this value by just around 20%. Finally, the highest Vickers hardness and fracture toughness were obtained for the sample reinforced with 25 vol% SiC w , standing at 29.3 GPa and 6.1 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

One of the most studied topics in analytical chemistry and physics is to develop bio-sensors. Aptamers are small single-stranded RNA or DNA oligonucleotides (5–25 kDa), which have advantages in comparison to their antibodies such as physicochemical stability and high binding specificity. They are able to integrate with proteins or small molecules, including intact viral particles, plant lectins, gene-regulation factor, growth factors, antibodies and enzymes. The aptamers have reportedly shown some unique characteristics, including long shelf-life, simple modification to provide covalent bonds to material surfaces, minor batch variation, cost-effectiveness and slight denaturation susceptibility. These features led important efforts toward the development of aptamer-based sensors, known as apta-sensors classified into optical, electrical and mass-sensitive based on the signal transduction mode. This review provided a number of current advancements in selecting, development criteria, and aptamers application with the focus on the effect of apta-sensors, specifically for disease-associated analyses. The review concentrated on the current reports of apta-sensors that are used for evaluating different food and environmental pollutants. [ABSTRACT FROM AUTHOR]

• Effects of magnetic field on heat transfer and entropy generation. • Inclined cavity with Straight, Inclined and Curved Blades containing nanofluid. • Solving nonlinear governing equations by finite volume method and SIMPLE algorithm. • Four different nano powders shapes, namely platelets, cylinders, Fins, and bricks. • The average Nusselt number and entropy generation are decreased by adding different nano powders. Nanopowder shapes are highly effective in nanofluids properties. This study was a numerical analysis of the effect of nanopowder morphology on the natural convection and irreversibilities of water/alumina nanofluids. To this end, a square enclosure was used with constant cold (T c) and hot (T h) temperatures at its right and left walls, respectively. The horizontal surfaces were isolated and the enclosure was exposed to a magnetic field. Two Fins were located on the left wall sharing the same temperature as the wall. The control volume method was used to derive the algebraic form of the equations, and a SIMPLE algorithm written in Fortran was used for the simulations. To investigate the effect of nanopowder shapes, four different shapes, namely platelets, cylinders, blades, and bricks, were used. For a better comparison, nanofluids with different morphologies were compared with a Brownian motion-incorporated model. The results showed that this model predicts the highest heat transfer rate and entropy generation. As its most important result, this paper concluded that free heat convection in nanofluids is not necessarily increased by addition of nanopowder, and in some cases, the Nu number and irreversibilities can be decreased because of the significant increase in nanofluid viscosity. It was also observed that the Nu rises with Ra and falls with the magnetic field intensity. Generally speaking, the greatest and lowest heat transfer coefficients were obtained using the Angled and straight Fins, respectively. [ABSTRACT FROM AUTHOR]

In this work, NiAl-WC composite was synthesized by a mechanical activated thermal explosion process from the powder mixture of nickel, tungsten, aluminum, and graphite. The phase, morphology, and microstructure development during milling and after the thermal explosion process were evaluated by XRD, FE-SEM, and TEM-EDS analysis techniques, respectively. The results indicated that after the thermal explosion of an as-mixed powder mixture, unreacted starting powder remained, and some new phases like Al 0.42 Ni 0.52 and W 2 C formed, which confirmed that the synthesis reactions were not completed. But, the final product of 5 h milled powder after the thermal explosion consisted of desired phases, NiAl and WC. XRD results of 5 h milled powder showed that the mechanical activation had two effects on NiAl-WC composite synthesis, reduction of crystallite and particle size, and better mixing of reactant powders and formation of W 2 C phase as an intermediate phase. These effects increased kinetics of reactions, and finally, NiAl-WC composite formed. [ABSTRACT FROM AUTHOR]

• Optimal geometry for parabolic solar collectors based on energy efficiency. • Nanofluid effect on parabolic solar collectors using two-phase simulation. • Eulerian-Eulerian method is employed to simulate two-phase nanofluid flow. • Energy efficiency for the dual-pass pipe is higher than that of single-pass one. In the present paper, the effect of U-shaped absorber tube on the performance of parabolic solar collector containing two-phase non-Newtonian nanofluids is studied numerically. The present study aims to obtain an optimal geometry for parabolic solar collectors based on energy efficiency. In this study, the effect of using nanofluid on parabolic solar collectors is investigated using two-phase simulation. The effect of Re number (2500

The combined impacts of inclined Lorentz force and thermal radiation on natural convection inside a porous chamber having micropolar nanoliquid and elliptical tilted heater are examined numerically. Micropolar fluid containing nanoparticles of copper oxide of low concentration circulates within the domain affected by the buoyancy and Lorentz forces. KKL approach is applied to define dependency of the nanofluid heat conductivity and viscosity on the nano-sized particles concentration and temperature, simultaneously. Governing equations with relevant boundary conditions written in non-dimensional stream function were solved by the Galerkin finite element method. An impact of important control parameters on micropolar nanofluid flow and heat exchange was analyzed. It was shown that change of the elliptical heater orientation reflects a significant modification of considered isolines and heat exchange rate. At the same time, average Nusselt number has maximum values for α = 0 and α = π and minimum value at α = π/2. [ABSTRACT FROM AUTHOR]

• A critique viewpoint is provided fro effectiveness. • Experiments are carried out to support the said viewpoint. • All possible curve behaviors of effectiveness are described. • Probable previous imperfect effectiveness analysis was mentioned. In this study attempts are made to clarify some hidden features of effectiveness concept (the ratio of actual heat transfer to maximum possible heat transfer) of heat exchangers and provide a critique viewpoint and comprehensive description about that. It is shown in present paper that the effectiveness parameter requires much more attention when it is used in fluid-flow parametric or sensitivity studies of heat exchangers and lack of consideration of its hidden features may lead to incorrect or imperfect decision-makings on curve behavior of effectiveness. Indeed, it is shown that the curve trend of effectiveness against the Reynolds number of one side of heat exchanger can be ascending, descending, or ascending-descending depending on the mass flow rate (Re number) of the other side fluid. Although this critique viewpoint is not considered as a weakness of the effectiveness definition for heat exchangers, inattention may lead to wrong or imperfect inferences in sensitivity analysis of effectiveness parameter. Moreover, it is not logical to provide empirical correlation for effectiveness against flow parameters without the consideration of described features of effectiveness in this study. In order to support the described viewpoint some experiments are performed on double helical tube heat exchanger to evaluate the related thermal parameters and describe the mentioned features of effectiveness statistically. However, the provided analysis is valid for any other type heat exchanger as well. [ABSTRACT FROM AUTHOR]

One of the famous blue pigments is cobalt aluminate which has a normal spinel that in this work has been synthesized with thermal decomposition technique via the help of olive leaf extract as a precipitation agent. Furthermore, CoAl 2 O 4 /SiO 2 , CoAl 2 O 4 /TiO 2 and CoAl 2 O 4 /graphene nanocomposites were prepared besides the pure one. To investigate the structure and composition of products, X-ray diffraction (XRD) pattern and Fourier transform infrared (FT-IR) analysis were served. Also, the morphologies of products were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the effect of different nucleation and growth conditions of the products were investigated. The hydrogen storage ability of the pure CoAl 2 O 4 nanostructures was investigated and to increase the hydrogen storage capacity, different CoAl 2 O 4 nanocomposites were prepared and studied. The maximum discharge capacity and Coulombic efficiencies are 2800 mAh/g and 62% that related toCoAl 2 O 4 /TiO 2 composition and CoAl 2 O 4 , respectively. • The CoAl 2 O 4 spinel was synthesized via olive leaf extract. • Hydrogen storage capacities of CoAl 2 O 4 with its composites were compared. • The Coulombic efficiency of samples was calculated, for the first time. • The discharge capacity increased with the increase of cycle number. • Hydrogen adsorption sites increased by repeating cycles of charge and discharge. [ABSTRACT FROM AUTHOR]

Pumped hydro storages (PHS) are the most common storage in the power system, which covers 99% of the total installed capacity of energy storage facilities in the world. Therefore, optimal offering and bidding strategies of PHS are essential in the energy market. Besides, various uncertainties, especially market price uncertainty is more challenging for PHS operator due to the imposed risks. Therefore, in order to optimally market-participation of these storages, in this paper a novel risk management approach called downside risk constraints (DRC) is applied to get the optimal offering and bidding strategies of the PHS. The DRC method is used along with the stochastic programming to model the risk associated with uncertainty parameter, including electricity market price uncertainty. Hence, ten scenarios are produced using the normal distribution function to model the uncertain parameter. Illustrated examples are determined how to deal with imposed risk from uncertainty by managing financial profit. Finally, according to the obtained results, using the proposed downside risk constraints, PHS operators can experience zero-risk conditions by decreasing their profit by 33% while risk-in-profit is reduced by 100% in versus risk-neutral strategy. • Risk evaluation of pumped hydro storage (PHS) using downside risk constraints. • Obtaining a zero-risk strategy for PHS in the market-participation process. • Providing a zero-risk bidding strategy for buying energy from the market. • Providing a zero-risk offering strategy for selling energy to the market. [ABSTRACT FROM AUTHOR]

• Optimal stochastic scheduling of plug-in electric vehicles (PEV) aggregators is studied. • Day-ahead and reserve markets price uncertainties are modeled via scenario approach. • Downside risk constraints (DRC) are proposed to consider the risk associated with uncertainties. • To survey the contribution of DRC implementation risk-averse strategy is presented and assessed with risk-neutral strategy. A single plug-in electric vehicle (PEV) cannot participate in reserve and day-ahead markets as they cannot meet the energy requirements of independent system operators (ISO). However, they can be gathered by a PEV aggregator and play a role in so called markets. On the other hand the PEV aggregators are to deal with the uncertainties that go along with these markets and can highly affect their profit. In order to cover these uncertainties scenario-based stochastic approach can be taken into to account to optimally schedule the PEV aggregators so that the maximum profit is obtained. The main contribution of this paper is to involve risk related uncertainties through the downside risk constraints (DRC) which results in risk-constrained stochastic optimization model. The main advantage of this method is that it can provide the owner of PEV aggregator with decisions that are made by considering various quantities for risk. CPLEX solver of GAMS software is employed to solve the problem which is formulated as mixed-integer linear programming (MILP) model. To investigate the accomplishment of DRC, risk-averse state of model is compared to risk-neutral which in former one the profit is reduced meanwhile that risk-in-profit (RIP) is declined. [ABSTRACT FROM AUTHOR]

In recent years, renewable energy resources such as wind and solar energy have been considered as the main alternative to fossil fuels due to their benefits such as economic benefits, low environmental pollution, and renewable power generation. The solar chimney is one of these alternatives with a simple structure that can be adopted for generating easy and clean energy. The application of solar chimney in desert areas of the Yazd city with high-intensity solar radiation is efficient and environmentally friendly. Due to the low efficiency of the solar chimney in the night times, a combined configuration has been proposed by considering the solid oxide fuel cell and solid oxide electrolysis cell for storing the surplus energy as Hydrogen for the night times. The paper also presents a developed version of deer hunting optimization algorithm to optimal designing of the economic aspect of the power plant. Simulation results are applied to two different seasons for more analysis and the results of the optimal system are compared with genetic algorithm (GA) and particle swarm optimization algorithm (PSO) to show the system efficiency. The results showed that 0.16 kg/s hydrogen is produced at the peak of the radiation in a district of Yazd city. The results also show the decreasing the loss value based on optimal economical designing gives 1,192,000,000$, 1,190,000,000$, and 8,645,000,000$ cost for the GA and PSO, and the proposed improved deer hunting optimization algorithm, respectively. It also shows that the energy generated by the presented configuration in the summer is higher than the winter. • New configuration is presented for supplying the power and the heat units. • A new improved optimization algorithm is proposed for optimal configuration. • The algorithm is improved version of deer hunting optimization algorithm. • The configuration is designed for a combined solar chimney power plants. • The algorithm is compared with GA and PSO. [ABSTRACT FROM AUTHOR]

There are three major applications (portable, stationary, transportation) of hydrogen energy (HE), and each application play a unique and important role in the sustainable development of energy system. In different regions within a country, different applications of HE are preferred. This paper therefore explores the process to decide the optimal region to develop each of the three subtypes of HE applications. To this end, the Analytical Hierarchy Process (AHP) and a fuzzy Technique the Order of Preference by Similarity to Ideal Solution (TOPSIS) method are used in the present study. Based on a literature review and in-depth interviews with officers, experts, the managers of HE-related enterprises, and consumers, the present study comes up with two selection criteria, namely, the acceptance on the applications of hydrogen energy (i.e., market entry barriers and customer's acceptance), and the integrity of hydrogen energy industrial chain on three applications (i.e., production stage, distribution stage, and marketing stage). This paper uses a case study to explore the functioning of three applications of hydrogen energy in the industrial, cultural and restricted residence regions. Four main findings emerges from this study: (1) the market structure of the portable, stationary and transportation application of HE should be pure competitive, oligopolistic, and monopolistic competition respectively; (2) the customer's acceptance for different applications is different, due to different neighborhood concerns about the quality of life; (3) the cost and benefit of different applications depend on different factors, including government policy, technological improvements and social preferences; (4) in order to promote all HE applications, the process to decide the optimal region to develop a specific HE application depends on the comparative advantages of the application. • Optimal multiple selections process for fostering applications of hydrogen energy were explored. • One of the selection criteria is the acceptance of the applications of hydrogen energy. • The other selection criterion is the integrity of hydrogen energy industrial chain. • The optimal solutions depend on the comparative advantages of different applications and regions. [ABSTRACT FROM AUTHOR]