82 research outputs found

    Size-dependent nonlinear analysis of composite laminated micro skew plates reinforced with functionally graded graphene sheets

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    The high mechanical strength and superior physical properties of graphene and its derivatives have made them an ideal choice for modern engineering structures. The use of graphene as nanofillers in reinforced polymer composites has led to the development of sustainable high performance composite materials. Such materials can be utilized in engineering structures not only to improve their structural performance but also to reduce their environmental impact as well. Skew plates are commonly used in aerospace structures and ship hulls. In this paper, a size-dependent nonlinear model is presented for bending analysis of composite laminated micro skew plates reinforced with functionally graded graphene sheets. The modified Halpin-Tsai micromechanical model and rule of mixture are considered for the effective mechanical properties of graphene sheets which vary continuously throughout the thickness of the skew plate. The Schapery's model is considered for the effective thermal properties. The skew plate is assumed in thermal environments while transversely loaded. The governing equations of the problem are derived based on the Mindlin plate theory and the modified coupled stress theory. Using the generalised differential quadrature method, the nonlinear governing equations are first converted into a set of linear algebraic equations and then solved to obtain the bending moment of the skew plate under different loading conditions. Results show that reinforcing composite laminated micro skew plates with functionally graded graphene sheets increases the overall stiffness and bending strength of the plate, enhancing its performance under large deflections. It has also been observed that the bending performance of the skew plate further enhances through changing the distribution pattern of the functionally graded graphene reinforcement as well as with an increase in the angle of the skew plate

    Comparison of Intelligent Systems, Artificial Neural Networks and Neural Fuzzy Model for Prediction of Gas Hydrate Formation Rate

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    The main objective of this study was to present a novel approach for predication of gas hydrate formation rate based on the Intelligent Systems. Using a data set including about 470 data obtained from flow tests in a mini-loop apparatus, different predictive models were developed. From the results predicted by these models, it can be pointed out that the developed models can be used as powerful tools for prediction of gas hydrate formation rate with total errors of less than 4%

    On buckling of cylindrical shells under combined loading

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    Effects of temperature on hematological and histopathological changes and survival rate of juvenile Fenneropenaeus vannamei experimentally challenged to White Spot Virus

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    Many shrimp farmers were suffering from White Spot Disease (WSD) onset in last decades. Oscillation of environmental factors could lead mortality in susceptible hosts. Our study was aimed to investigate the effect of different temperatures on juvenile Fenneropenaeus vannamei experimentally exposed to White Spot Virus (WSV). Five hundred and forty juveniles were distributed among 3 treatments in triplicates, 22, 25 and 30°C and experimentally WSV were injected in the shrimps. Our results showed mortality started at 36 h post inoculation (hpi) in the treatment at 25°C (T25), meanwhile the mean value of mortality percent at 54 hpi in T25 (71.10±17.35) showed the significant difference (p=.045) with T22 (3.33±3.33) and T30 (Not Observed, NO.). Our results suggest that in site selection, in primary stage of farm designing, water temperature at more than 29°C, should be considered as key environmental factor. This finding can lead us that why the White Spot Disease occurred with high mortality in some area when the days of shrimp culture were prolonged until mid autumn

    Hemocytosis, a new disease in cultured shrimp, Fenneropenaeus indicus

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    Certain parasites can cause severe diseases in shrimp. Among these, protozoa are very important. The objective of our study was to describe the signs, prevalence, and intensity of hemocytosis, a new disease in shrimp, Fenneropenaeus indicus. The experimental design included three groups, one treatment as infected shrimp or group B and 2 controls with non-infected but exposure to White Spot Syndrome Virus (WSSV) shrimp as group A and non-infected non-exposure to WSSV shrimp as group C in triplicate. The results revealed that Hemocytosis associated with a decrease in hyalinocytes and large-granulocytes (less than 8%) and a considerable increase in semi-granulocytes in group A and B in contrast to group C that Hyalinocyte increased. This infection made the shrimp susceptible to WSSV disease. It is believed that Hemocytosis causes a condition which can result in a rapid mortality among susceptible species, F. indicus when exposure to WSSV is occurred

    Adaptation, growth and survival of tilapia (Oreochromis niloticus) in Bafgh brackish water

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    An experiment was conducted to evaluate the possibility of adaptation, growth and survival of Nile tilapia (Oreochromis niloticus) with 0.3g initial weight and red tilapia (Oreochromis sp.) with 0.7g initial weight in underground brackish water. Fry of Nile tilapia and red tilapia imported from Indonesia and after passing larviculture (25g) were examined separately in fiber glass tank by two replicate. Fish were fed at a restricted feeding program according to standard table during the light period. The results showed that some growth factors such as final weight, final length, daily growth rate, specific growth rate and weight gain in Nile tilapia were slightly higher than red tilapia but other factors such as survival and feed conversion rate in red tilapia were slightly higher than Nile tilapia. There were no significantly differences at 99% level among these factors. Length-weight relationship equation was w = 0.012×TL3.189 in Nile tilapia and w = 0.014×TL3.119 in red tilapia (r2 = 0.99), b value were 3.189 and 3.119 respectively in Nile and red tilapia representing isometric growth. According to the reliable growth and high survival rate (98%), it seems that both Nile and red tilapia could be good candidates for rearing in brackish water condition

    CFD-DEM Analysis of Particle Attrition in a Jet in a Fluidised Bed

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    In fluidised bed processes, the solids are in vigorous motion and thus inevitably subjected to mechanical stresses due to inter-particle and particle-wall impacts. These stresses lead to a gradual degradation of the particles by surface wear, abrasion and body fragmentation commonly termed attrition. One significant contribution of attrition comes from the air jets of the fluidised bed distributor. Particles are entrained into the air jet, where they get accelerated and impacted onto the fluidised bed particles. The jet induced attrition only affects the part of the bed which is limited by the jet length, where the mode of attrition is largely collisional. The overall jet attrition rate is therefore the result of the combination of the single particle damage and the flux of particles entering into that region. The attrition behaviour of particles in the jet region is analysed by evaluating their propensity of breakage experimentally and by simulating an air-jet in a bed of particles by CFD-DEM. The frequency of collisions and impact velocities are estimated from which the attrition due to a single air-jet is predicted

    Combined effect of moisture and electrostatic charges on powder flow

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    peer reviewedIt is well known in industrial applications involving powders and granular materials that the relative air humidity and the presence of electrostatic charges influence drastically the material flowing properties. The relative air humidity induces the formation of capillary bridges and modify the grain surface conductivity. The presence of capillary bridges produces cohesive forces. On the other hand, the apparition of electrostatic charges due to the triboelectric effect at the contacts between the grains and at the contacts between the grains and the container produces electrostatic forces. Therefore, in many cases, the powder cohesiveness is the result of the interplay between capillary and electrostatic forces. Unfortunately, the triboelectric effect is still poorly understood, in particular inside a granular material. Moreover, reproducible electrostatic measurements are difficult to perform. We developed an experimental device to measures the ability of a powder to charge electrostatically during a flow in contact with a selected material. Both electrostatic and flow measurements have been performed in different hygrometric conditions. The correlation between the powder electrostatic properties, the hygrometry and the flowing behavior are analyzed. © The Authors, published by EDP Sciences, 2017

    The study of adaptation, growth and survival of tilapia (Oreochromis.sp) in Bafgh brackish water

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    An experiment was conducted to evaluate the possibility of adaptation, growth and survival of Red and Nile tilapia (Oreochromis niloticus) in underground brackish water. Fry with 0.3 and 0.7 g initial weight imported from Indonesia and after passing larviculture (20 g) were examined separately in fiber glass tank and earthen pond by two replicate. Fish were fed three times a day by using manual food (cp=33.79) and carp food (cp=25.05) at a restricted feeding program according to standard table during the 72 days rearing stage at light period. The results showed that some growth factors such as final weight, final length, daily growth rate, specific growth rate and weight gain in Nile tilapia were slightly higher than red tilapia but other factors such as survival and feed conversion rate in red tilapia were slightly higher than Nile tilapia. There were no significantly differences at 99% level among these factors. Length-weight relationship equation was w = 0.020 × TL3.012 in Nile tilapia and w = 0.015×TL3.086 in red tilapia (r^2 = 0.98), b value was 3.012 and 3.086 respectively in Nile and red tilapia representing isometric growth. So according to the results, good growth and high survival rate, it seems that both Nile and red tilapia could be good candidates for reproducing and rearing in brackish water condition

    Possibility of trout farms efluent return to groundwater In non-agricultural seasons

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    This project is trying to investigate water contamination after use in ponds. For this aquaculture status, physical and chemical water properties, microbial pollutants and heavy metals levels in the some of trout ponds effluent in East Azerbaijan province were evaluated in 2007 to 2009. The information of groundwater and climate conditions in ten years, Drilling and wells piezometric Information, in local wells are reviewed. According to data obtained from analysis of water samples in the output pools range studied concentrations(term mg/l) some parameters are as follows:(BOD: 1.9-3.2), (COD: 3.4-34.1), (TSS: 26.6-42.7), (N-NO_2:0.003-.136),(P-Po4:0.0170.067), (pH:7.75-8.28). Electrical conductivity (500 ±2 to 1129±144 term µm/cm) in the effluent ponds. Based on the results of we can say that between input and effluent ponds in the review of all factors as chlorine, sulfate, sodium, potassium, total nitrogen, soluble phosphorus, total phosphorus, calcium, total hardness, magnesium, alkalinity and silica significant changes not be observed. Review of water analysis data to some factors (such as: water temperature, EC, pH, NO_2, CO_2, HCO_3, CO_3, DO, COD, BOD) and compare this data with the authorities standard confirmed that the All factors mentioned in effluent is allowed now. In terms of microbial contamination and heavy metals (Zn, Cu, Ca, Pb, Fe, Cr) is no pollution. Appropriate strategies for removing suspended materials must to use. We can use Watershed Management solutions to inject output water to the underground table. Should be noted status change (eg change in flow rate, an unusual increase in temperature, fish density increasing, reducing food quality, lack of appropriate management actions and ...) may reduce the effluent quality and the ability of injection water underground to lose. In this case, measures must be for wastewater treatment and improve the quality ponder
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