Improved extra group network: a new fault-tolerant multistage interconnection network

Supersystems are shown to provide enough computational power to solve complex problems on a real-time basis. In all these systems, the computational parallelism is obtained from multiple processors. Multistage interconnection networks (MINs) play a vital role on the performance of these multiprocessor systems. This paper introduces a new fault-tolerant MIN named as improved extra group network (IEGN). IEGN is designed by existing extra group (EGN) network, which is a regular multipath network with limited fault tolerance. IEGN provides four times more paths between any source–destination pairs compared with EGN. The performance of IEGN has been evaluated in terms of permutation capability, fault tolerance, reliability, path length, and cost. It has also been proved that the IEGN can achieve better results in terms of fault tolerance, reliability, path length and cost-effectiveness, in comparison to known networks, namely, EGN, augmented baseline network, augmented shuffle-exchange network, fault-tolerant double tree, Benes network, and Replicated MIN.     

A new synthetic metamodel methodology for liquid‐propellant engine's cooling system optimization

The present paper strives for optimization of the cooling system of a liquid‐propellant engine (LPE). To this end, the new synthetic metamodel methodology utilizing the design of experiment method and the response surface method was developed and implemented as two effective means of designing, analyzing, and optimizing. The input variables, constraints, objective functions, and their surfaces were identified. Hence, the design and development strategy of combustion chamber and nozzle was clarified, and 64 different experiments were carried out on the RD‐161 propulsion system, of which 47 experiments were approved and compatible with the problem constraints. This engine used all three modes of cooling: the radiation cooling, the regenerative cooling, and the film cooling. The response surface curves were drawn and the related objective function equations were obtained. The analysis of variance results indicate that the developed synthetic model is capable to predict the responses adequately within the limits of input parameters. The three‐dimensional response surface curves and contour plots have been developed to find out the combined effects of input parameters on responses. In addition, the precision of the models was assessed and the output was interpreted and analyzed, which showed high accuracy. Therefore, the desirability function analysis has been applied to LPE's cooling system for multiobjective optimization to maximize the total heat transfer and minimize the cooling system pressure loss simultaneously. Finally, confirmatory tests have been conducted with the optimum parametric conditions to validate the optimization techniques. In conclusion, this methodology optimizes the LPE's cooling system, a 2% increase in the total heat transfer, and a 38% decrease in the pressure loss of the cooling system. These values are considerably large for the LPE design.     

Development of an electrochemical sulfite biosensor by immobilization of sulfite oxidase on conducting polyaniline film

In this work, a biosensor was developed for the determination of sulfite. The bioelectrochemical response of the enzyme-modified electrode based on electrochemical incorporation of sulfite oxidase into polyaniline aluminum modified electrode was investigated. Electropolymerization of polyaniline and simultaneous immobilization of sulfite oxidase on the aluminum were performed in an aqueous solution containing sulfite oxidase. The sulfite biosensor constructed by cycling the potential scan between +1.2 and ?0.5 V vs. saturated calomel electrode (SCE) that showed a sensitive response to sulfite with a linear calibration graph in the concentration ranges of 0.006–5 mM sulfite and detection limit 0.002 mM sulfite (S/N = 3). The obtained results from the stability tests of the biosensor show that the sulfite biosensor can be used for two different applications, for immediate usage and long term usage. Also, the bioelectrochemical response of the enzyme-modified electrode as a sulfite biosensor was evaluated at different experimental conditions. The optimum pH when using phosphate buffer and temperature were 8.5 and 35 °C, respectively. Finally, the apparent Michaelis–Menten constant was determined which has value of 0.365 mM which is really close to the magnitude of the Michaelis–Menten constant of free sulfite oxidase that shows the enzyme was not chemically modified and has its usual kinetic reaction.     

Effects of thermal and mechanical activation methods on compressive strength of ordinary Portland cement–slag mortar

Activation methods and curing regimes have crucial effects on the strength of mortars and concretes. The objective of this investigation is to examine the early and later compressive strength of activated ordinary Portland cement (OPC)–ground granulated blast-furnace slag (GGBFS) mortars and identify the most effective activation technique. The methods of activation used were thermal, mechanical and thermal–mechanical combined. Two curing regimes were adopted and five groups of mortars were prepared. It was observed that OPC–GGBFS mortars have greater sensitivity to OPC mortars against the curing regimes. However, the study revealed that there was no particular activation method which when used gave the best results for both early and later strengths and did not cause strength loss. It also proved that the most effective activation method for early strength is a combination of both the thermal and mechanical, while for later strengths, none of the activation methods was recommended.     

On the dispersion of CNTs in polyamide 6 matrix via solution methods: assessment through electrical, rheological, thermal and morphological analyses

In this study, polyamide 6 (PA 6)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by different solution methods based on phase inversion, drop-casting and simple evaporation processes. Optical microscopy and field emission scanning electron microscopy techniques were used to investigate the dispersion states of the nanotubes in PA 6 matrix. The results indicated that the dispersion state of MWCNTs in the nanocomposites prepared by the phase inversion-based method was better than those in the nanocomposites prepared by the other two methods. Electrical, rheological, differential scanning calorimetry and thermo-gravimetric analysis measurements showed that the PA 6/MWCNTs nanocomposites prepared by the phase inversion-based method had higher electrical conductivity, storage modulus, crystallization temperature and thermal stability in comparison with those prepared by the other two methods, attributed to the better dispersion state of MWCNTs. These results confirmed achievement of a good dispersion state of MWCNTs within PA 6 matrix by the phase inversion-based efficient approach.     

Renewable energy harvesting with the application of nanotechnology: A review

It is believed that fossil fuel sources are exhaustible and also the major cause of greenhouse gas emission. Therefore, it is required to increase the portion of renewable energy sources in supplying the primary energy of the world. In this study, it is focused on application of nanotechnology in exploitation of renewable energy sources and the related technologies such as hydrogen production, solar cell, geothermal, and biofuel. Here, nanotechnologies influence on providing an alternative energy sources, which are environmentally benign, are comprehensively discussed and reviewed. Based on the literature, employing nanotechnology enhances the heat transfer rate in photovoltaic/thermal (PV/T) systems and modifies PV structures, which can improve its performance, making fuel cells much cost‐effective and improving the performance of biofuel industry through utilization of nanocatalysts, manufacturing materials with high durability and lower weight for wind energy industry.     

An artificial intelligence approach to optimization of an off-grid hybrid wind/hydrogen system

Off-grid electrification of remote areas using a hybrid renewable energy scheme is a requirement to achieve the goals of sustainable development. However, the optimization and sizing for the capacity of such systems are challenging. In this regard, this study targets an improved optimization algorithm with high efficiency for optimization and long-term capacity planning of an off-grid hybrid renewable energy scheme composed of wind, fuel cell, and hydrogen storage schemes. The suggested methods are three improved versions of the global dynamic harmony search to do pitch adjustment mechanism. The objective function of this study is to reduce the total net annual cost of the system and the loss of power supply probability to a minimum. The performance of this hybrid system is examined via a simulation study, which had been performed on a remote area located in eastern Iran over a long period. The results of the three improved proposed algorithms are compared with the original global dynamic harmony search algorithm. Also, sensitivity analysis is proposed to showcase the influence of uncertainties on the system and input parameters on the algorithm. The simulation results indicate that three improved versions of the global dynamic harmony search algorithm ?nd more promising results than the original algorithm, and confirm the superior accuracy, convergence speed, and robustness of the global dynamic harmony search-II. Also, reliability level and iteration values have a considerable impact on the total net annual cost of the optimal hybrid energy system based on wind and hydrogen energy.     

A lab-scale set up for thermal radiation experiments with cold junction compensation

The concepts of thermal radiation heat transfer are not tangible for many students. Experiments relied on various parameters can clarify the concepts of this mode of heat transfer.A lab-scale set up is described to study the thermal radiation heat transfer experiments. An electrical circuit of the thermopile sensor is designed and manufactured to provide experimental data.The validity of Inverse Square, Stefan–Boltzmann, and Kirchhoff Laws are investigated experimentally in the setup. Results indicate that, it is necessary to consider temperature shifts in the thermopile cold junction which is a potential source of error. Therefore, the output voltage, corresponding to the sensor temperature, should be noted upon each measurement.Moreover, during the experiment, thermopile characteristics which affected the recorded data are reported. Wide angle of view and spectral response of the thermopile are found to be the main source of errors.Finally, in order to decrease errors, some suggestions as the feedback of students experiments and comments, are proposed to improve both the methods and the instruments.     

Combination of Plasma Functionalization and Phase Inversion Process Techniques for Efficient Dispersion of MWCNTs in Polyamide 6: Assessment through Morphological,Electrical, Rheological and Thermal Properties

Different contents of multiwalled carbon nanotube (MWCNTs) functionalized by He-dielectric barrier discharge (DBD) plasma followed by an exposure to NH₃ were incorporated into PA6 matrix via a phase inversion based solution method. Optical and electron microscopic results were indicative of the excellent dispersion state of the MWCNTs. The differential scanning calorimetry and thermogravimetric analysis measurements revealed that even addition of a slight amount of the MWCNTs significantly increased the thermal stability and crystallization temperature. Moreover, the low electrical percolation threshold of the PA 6/functionalized MWCNTs nanocomposites was another confirmation for achieving a good dispersion state of MWCNTs using this approach.     

Development of macroporous nanocomposite scaffolds of gelatin/bioactive glass prepared through layer solvent casting combined with lamination technique for bone tissue engineering

In this study, macroporous bioactive nanocomposite scaffolds were developed using cross-linked gelatin and bioactive glass (BaG) nanoparticles. First, BaG nanoparticles were synthesized via sol–gel method and characterized. Then, macroporous nanocomposites were prepared through layer solvent casting combined with freeze-drying and lamination techniques. This research has developed a new composition to produce a new bioactive nanocomposite which is porous with three-dimensional (3D) inter-connected microstructure, pore sizes are 200–500 μm, porosity are 72–86% and BaG nanoparticles are dispersed evenly among cross-linked gelatin matrices. It is mentionable that in this study, we have reported the formation of chemical bonds between BaG nanoparticles and gelatin for the first time. Finally, the in vitro cytocompatibility of the nanocomposite scaffolds was tested using SaOS-2 cell line.