The effect of refrigerant combinations on performance of a vapor compression refrigeration system with dedicated mechanical sub-cooling

Performance characteristics due to use of different refrigerant combinations in vapor compression cycles with dedicated mechanical sub-cooling are investigated. For scratch designs, R134a used in both cycles produced the best results in terms of COP, COP gain and relative compressor sizing. In retrofit cases, considering the high sensitivity of COP to the relative size of heat exchangers in the sub-cooler cycle and the low gain in COP obtained due to installation of a dedicated sub-cooling cycle when R717 is the main cycle refrigerant, it seems that dedicated mechanical sub-cooling may be more suited to cycles using R134a as the main cycle refrigerant rather than R717. With R134a as the main cycle refrigerant, no major difference was noted, by changing the sub-cooler cycle refrigerant, in the degradation of the performance parameters such as COP and cooling capacity, due to equal fouling of the heat exchangers.     

A genetic algorithm for the stochastic mixed-model U-line balancing and sequencing problem

Mixed-model assembly lines are widely used to improve the flexibility to adapt to the changes in market demand, and U-lines have become popular in recent years as an important component of just-in-time production systems. As a consequence of adaptation of just-in-time production principles into the manufacturing environment, mixed-model production is performed on U-lines. This type of a production line is called a mixed-model U-line. In mixed-model U-lines, there are two interrelated problems called line balancing and model sequencing. In real life applications, especially in manual assembly lines, the tasks may have varying execution times defined as a probability distribution. In this paper, the mixed-model U-line balancing and sequencing problem with stochastic task times is considered. For this purpose, a genetic algorithm is developed to solve the problem. To assess the effectiveness of the proposed algorithm, a computational study is conducted for both deterministic and stochastic versions of the problem.     

From Blindness to Foraging to Sensing to Sociality: an Evolutionary Perspective on Cognitive Radio Networks

Mobile Networks and Applications - Wireless communication is an increasingly important aspect of the digital ecosystem. The Internet of Things reached 4+ billion devices in 2014, and is expected to...     

Biocontrol ability and action mechanisms of Aureobasidium pullulans GE17 and Meyerozyma guilliermondii KL3 against Penicillium digitatum DSM2750 and Penicillium expansum DSM62841 causing postharvest diseases

Epiphytic yeasts were isolated from different cultivars of apples and lemons and identified by a combination of PCR-RFLP of 5.8S rRNA region and sequencing of D1/D2 domain of the 26S rRNA gene. Among 69 isolates, Aureobasidium pullulans GE17 and Meyerozyma guilliermondii KL3 strains showed the greatest antagonistic activity against two significant apple and lemon postharvest pathogens, Penicillium expansum DSM62841 (blue mold) and Penicillium digitatum DSM2750 (green mold), after preliminary screening. Yeasts were applied as single and mixed cultures with two different cell concentrations of 10⁶ and 10⁸ cells/ml in the present study. It was determined that antagonistic activity of two yeast strains studied emerged with a combination of several mechanisms of action including competition for space and nutrients, production of volatile organic compounds (VOCs), secretion of extracellular lytic enzymes and inhibition of fungal spore germination. The highest inhibition of mycelial growth on P. expansum DSM62841 and P. digitatum DSM2750 (83.4% and 74.7%, respectively) was achieved by utilization of single culture of A. pullulans GE17. Otherwise, the application of mixed culture at the ratio of 10⁸ cells/ml inhibited spore germination of both pathogens from 86% to 95%. Results of this study suggest that an increase in yeast cell concentrations positively affected their biocontrol activity against blue and green molds. According to the results, employing single culture of M. guilliermondii KL3 did not exhibit effective antagonistic activity against blue and green molds. However, utilization of A. pullulans GE17 alone and mixed culture showed succesfull controlling against both P. expansum DSM62841 and P. digitatum DSM2750.     

Peristaltic pumping with double diffusive natural convective nanofluid in a lopsided channel with accounting thermophoresis and Brownian moment

In the current study, double-diffusive natural convective peristaltic flow of a nanofluid with induced magnetic field in an asymmetric porous channel is discussed. The five coupled equations are solved analytically using with new analytical techniques detail of which is given in solution section. The analytical solutions for pressure gradient and pressure rise, velocity profile, temperature, solutal concentration, and nanoparticle fraction are evaluated and presented through graphs.

     

All ambient environment‐based perovskite film fabrication for photovoltaic applications

Low‐temperature solution process‐able perovskite solar cells are highly desirable for future photovoltaics. Chemical root was utilized to synthesize and optimize mixed halide‐based MAPbIBr₂ light absorber perovskites on electron transport layer of TiO₂ nanoparticles in ambient atmosphere. For the first time all synthesis work was performed in an ambient environment and observe material behavioral characteristics. To accurately control the film morphology, one‐step deposition technique was applied to investigate material's optoelectronic behavior. The role of the perovskite structure, physical, and optical properties in planner device architecture was studied through ultraviolet visible, X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscope characterization techniques to confirm a band gap of 1.76 eV with cubic crystalline structure having a particle size of 12.5–13.0 nm, which is highly suitable for perovskite solar cells.     

Facile hydrothermal synthesis of 3D flower‐like La‐MoS2 nanostructure for photocatalytic hydrogen energy production

Three‐dimensional (3D) flower‐like MoS₂ nanostructures were prepared via facile and cost‐effective hydrothermal method by varying hydrothermal temperature (180°C, 200°C, and 220°C) and reaction time (6, 12, 24, and 36 hours). The results demonstrated that the sample prepared at 200°C for 24 hours have 3D flower‐like MoS₂ nanostructure (SEM) with hexagonal phase structure (XRD). Moreover, this novel photocatalyst was also modified by lanthanum element (La³⁺) with varying La³⁺ atomic ratio (0.5%, 1%, 2%, 3%, and 4%). Interestingly, the La³⁺ incorporation into MoS₂ has good effect on the specific surface area and optical properties of MoS₂ photocatalyst. Furthermore, the flower‐like 3%LaMoS₂ nanostructure photocatalyst exhibited 5.2‐times higher efficiency for H₂ evolution via water splitting as compared with pure MoS₂ under the same conditions. This superior efficiency of the photocatalyst for H₂ production arises from the positive synergistic effect between MoS₂ and lanthanum in the composite photocatalyst due to higher surface area, enhanced light absorption, and inhibited electron‐holes pair recombination. This study presents an expensive photocatalyst for energy production via water spitting.     

Hybrid Anomaly Detection by Using Clustering for Wireless Sensor Network

Wireless Personal Communications - Performance of wireless sensor network are highly prone to network anomalies particularly to misdirection attacks and blackhole attacks. Therefor intrusion...     

On MHD radiative Jeffery nanofluid flow with convective heat and mass boundary conditions

Neural Computing and Applications - The prime objective of present exploration is to study effects of magnetohydrodynamic, Joule heating and thermal radiation on an incompressible Jeffrey nanofluid...