Sharif Digital Repository

In this research, low density polyethylene (LDPE) and poly ethylene-co-vinyl acetate (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was Film Blowing and ThermalDry Phase Inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. The Barometric method was considered and measurements were based on ASTM standard. To study film cross-section morphology in EVA, Scanning Electron Microscopy (SEM) was applied. From results we considered that the amount of permeability and solubility were decreased by increasing film... 

One of the most conventional and energy efficient methods to improve the engineering properties of concrete is the utilization of waste materials and by-products. Among agricultural wastes, rice husk ash (RHA) has exhibited the greatest potential to enhance the characteristics of cement mixtures. However, the investigations on the properties and performance of RHA are slim compared to its potential advantages and few systematic studies can be found in the literature regarding parameters influencing the chemo-physical and microstructural characteristics of RHA along with its performance in cement mixtures. In this study, the effect of retention time of rice husk is systematically... 

In this research, low density polyethylene (LDPE) and poly(ethylene-co-vinyl acetate) (EVA) were used as polymeric materials. The methods used to produce LDPE and EVA was film blowing and thermal-dry phase inversion. The amount of permeability, diffusivity and solubility of O2 and CO2 through above polymers were obtained and also the effect of temperature, pressure and film thickness for LDPE was measured. To study film cross-section morphology in EVA, scanning electron microscopy (SEM) was applied. The results showed that the amount of permeability and solubility were decreased by increasing film thickness but diffusivity was increased. However, by increasing temperature, permeability,... 

This paper investigates the effects of acid normality (0.01-6 N HCl) and combustion retention time (0.25- 16 hours) on the pozzolanic properties of pre-combustion acid-treated rice husk ash. The pozzolanic reactivity was quantified by adding ground ash to saturated Ca(OH)2 solutions and monitoring the time-dependent electrical conductivity and pH of the solutions. Also, the strength activity of ashes from different processes was measured by testing the compressive strength of mortars. It was observed that acid treatment results in ashes with higher SiO2 content, lower alkali and unburned carbon content, better grindability, and smaller particle size, in comparison with ash from non-acid... 

Evapotranspiration is one of the main components of water and energy balance. In this study, we compare two ET products, suitable for regional analysis at high spatial resolution: The recent WaPOR product developed by FAO and METRIC algorithm. WaPOR is based on ETLook, which is a two-source model and relies on microwave images. WaPOR is unique as it has no limitation under cloudy days, but METRIC is limited by clouds. METRIC and WaPOR are more sensitive to land surface temperature and soil moisture, respectively. Using two years (2010 and 2014) of data over Lake Urmia basin, we show that in most areas, ET from METRIC is higher than WaPOR and the difference has an ascending trend with the... 

This paper proposes effective approach for determining appropriate crowbar resistance value to be able to improve the brushless doubly fed induction generator ride through capability during any asymmetrical voltage dip scenarios. The brushless DFIG has great potential for wind power plants particularly in offshore applications where maintenance is a major concern. Dynamic behavior of the machine is studied using two axis model and a more precise equivalent circuit model is extracted for analyzing machine behavior under fault conditions. Important limits and constraints in the use of crowbar are identified and discussed in detail. It is shown that large crowbar values can lead to considerable... 

The virtual reality (VR) applications in entertainment and tourism industry have become growingly intense among generation Z. Interestingly, some pilot research on tourism studied concluded the positive impact of its flow experience on adoption of VR tourism, which is also driving the risk of immersive addictive. In the context of tourism and information and communication technology (ICT)-based innovation, there is a lack of immersive addictive behavior (IAB)-related literature. In addition, during the currently ongoing pandemic crisis, VR technology has gained particular importance in the tourism industry among generation Z. The present venture underlines the mechanism of IAB, investigates... 

In the published article, there was an error regarding the affiliations for Saba Saneinia. As well as having affiliation 1, she should also have Key Laboratory of Immersive Media Technology (Anhui Xinhua Media Co, Ltd.), Ministry of Culture and Tourism, Hefei, China. In the published article, there was an error regarding the affiliations for Rongting Zhou. As well as having affiliations 2, he should also have Key Laboratory of Immersive Media Technology (Anhui Xinhua Media Co, Ltd.), Ministry of Culture and Tourism, Hefei, China. In the published article, there was an error regarding the affiliations for Fahad Asmi. As well as having affiliations 2, he should also have Key Laboratory of... 

The Brushless Doubly-fed Induction Generator (BDFIG) has high potential for wind energy systems, especially for offshore applications where minimum maintenance is vital. The machine low voltage ride through (LVRT) capability in the light of current grid code requirements was investigated using a precise dynamic model. This is particularly important for future multi- MW BDFIGs. This paper shows the necessity for improvements of the BDFIG LVRT capability with presenting a comprehensive analytical study during asymmetrical voltage dips. Analytical studies are conducted to extract a more precise equivalent circuit model of the BDFIG used for analyzing machine dynamic behavior under various fault... 

Ternary novel BiOI@MIL-88A(Fe)@g-C3N4 nanocomposite with core@shell structure was successfully synthesized by hydrothermal method. fabricated photocatalysts were characterized and results confirmed the formation of MIL-88A(Fe)@g-C3N4 core@shell structure and subsequently BiOI decoration on the surface of MIL-88A(Fe)@g-C3N4. Photocatalytic performances of prepared samples were investigated for degradation of Acid Blue 92 (AB92), Rhodamine B (RhB) and phenol under visible irradiation. It is clearly demonstrated that the as-prepared ternary BiOI@MIL-88A(Fe)@g-C3N4 composites exhibits exceptional visible-light photocatalytic activities for cationic, anionic as well as neutral pollutant molecules... 

Bi-evaporator electricity/cooling cogeneration systems can be a favorable addition to the integrated power plants since the generated cooling load should be addressed for different demands. More consequentially, taking advantage of such an integral set-up operated with highly reliable heat source such as biogas can be appreciable for nowadays industries. Regarding this demand, an innovative bi-evaporator electricity/cooling cogeneration system is introduced at first. Next, the suggested system is integrated with a gas turbine cycle fueled by biogas. In the subsequent part, the plausibility of the introduced integrated power plant is examined from first and second laws of thermodynamics (as... 

An innovative bi-evaporator electricity/cooling cogeneration system fueled by biogas is introduced. The plausibility of the introduced integrated power plant is examined from thermodynamic and economic vantage points. Later, single- and multi-objective optimization of the reckoned system are achieved by selecting appropriate parameters as decision variables and thermal and exergy efficiencies and total unit product cost (TUPC) of the system as objective functions. Four optimum modes of thermal efficiency optimum design (TEOD), exergy efficiency optimum design (EEOD), cost optimum design (COD), and multi-objective optimum design (MOOD) are selected for optimization and the attained results... 

The nanocomposite of g-C 3 N 4 supported by MIL-88A has been prepared via a facile hydrothermal method. The photocatalytic performance of as-prepared composite (MIL-88A/g-C 3 N 4 ) was examined by the degradation of the Methylene Blue (MB) solution under visible light. The characterization test illustrated that the MIL-88A particles were successfully dispersed on the surface of g-C 3 N 4 structure. Photoactivity results demonstrated that the MIL-88A/g-C 3 N 4 /H 2 O 2 exhibited dramatically visible light photocatalytic performance. Hydroxyl radicals ([rad]OH) are generated by dissociation of H 2 O 2 under visible irradiation can remarkably enhance the degradation rate of MB molecules.... 

In this study, we synthesized novel visible light photocatalyst MIL-88A/BiOI using depositing BiOI particles on the surface of a metal–organic framework (MIL-88A). Photocatalytic application of binary composite MIL-88A/BiOI was obtained by discoloration of Methylene Blue (MB) and Acid Blue 92 (AB92) in aqueous solution under visible light source. The photodegradation experiments for treating organic dyes show that the MIL-88A/BiOI heterojunction structure possess a higher rate for decomposition of dyes due to the decreased aggregation of the BiOI nanoparticles, effective charge carrier separation and the synergistic effect between MIL-88A and BiOI samples as a heterojunction. Also, the... 

Despite the fact that humidification-dehumidification (HDH) desalination systems can be driven by various renewable or waste heat energies, many of the available renewable technologies are expensive in some parts of the globe. Hence, proposing and developing high-efficient mechanical-based HDH units can be an encouraging alternative which is more highlighted in recent investigations. In pursuance of this objective, three innovative mechanical-driven HDH units are simulated and the results are compared with each other. The simulated hybrid desalination system consists of a HDH unit and an ethane ejector expander transcritical refrigeration cycle (ethane-EETRC). The simulated hybrid systems... 

Among different types of geothermal processing used in the energy conversion systems, flash-binary geothermal can be the best scenario for high-temperature geothermal sources. Reviewing the available literature it can be found that the flash-binary geothermal power plants have a great potential to be extended to trigeneration systems, nonetheless they have received less attention. In this regard, a new trigeneration system for freshwater, power, and cooling production is devised using a flash-binary geothermal heat source at 170°C. In this devised trigeneration system, a humidification-dehumidification (HDH) unit is used as a binary cycle. Another merit of the devised trigeneration system is... 

Anaerobic fermentation of crop straw/animal dug can be the most appropriate solution for biomass conversion into applicable renewable energy-based fuels. However, due to the imperfection matching between the biogas combustion process and energy conversion system, a painstakingly design procedure is required to devise high-efficient energy system for capturing biogas efficiently. For this aim, a new trigeneration system driven by biogas is devised for electricity, refrigeration, and potable freshwater generation. The devised system encompasses a gas turbine (GT) cycle, a new cooling/electricity cogeneration system based on organic Rankine cycle (ORC) and ejector cooling cycle (ECC), and a...