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  • 1
    Publication Date: 2019
    Description: A thermodynamic assessment is conducted for a new configuration of a supercritical water gasification plant with a water–gas shift reactor. The proposed configuration offers the potential for the production of syngas at different H2:CO ratios for various applications such as the Fischer–Tropsch process or fuel cells, and it is a path for addressing the common challenges associated with conventional gasification plants such as nitrogen dilution and ash separation. The proposed concept consists of two reactors, R1 and R2, where the carbon containing fuel is gasified (in reactor R1) and in reactor R2, the quality of the syngas (H2:CO ratio) is substantially improved. Reactor R1 is a supercritical water gasifier and reactor R2 is a water–gas shift reactor. The proposed concept was modelled using the Gibbs minimization method with HSC chemistry software. Our results show that the supercritical water to fuel ratio (SCW/C) is a key parameter for determining the quality of syngas (molar ratio of H2:CO) and the carbon conversion reaches 100%, when the SWC/C ratio ranges between two and 2.5 at 500–1000 °C.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 2
    Publication Date: 2019-11-01
    Print ISSN: 0360-5442
    Electronic ISSN: 1873-6785
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Elsevier
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  • 3
    Publication Date: 2014-01-01
    Description: Different numerical methods have been implemented to simulate internal natural convection heat transfer and also to identify the most accurate and efficient one. A laterally heated square enclosure, filled with air, was studied. A FORTRAN code based on the lattice Boltzmann method (LBM) was developed for this purpose. The finite difference method was applied to discretize the LBM equations. Furthermore, for comparison purpose, the commercially available CFD package FLUENT, which uses finite volume Method (FVM), was also used to simulate the same problem. Different discretization schemes, being the first order upwind, second order upwind, power law, and QUICK, were used with the finite volume solver where the SIMPLE and SIMPLEC algorithms linked the velocity-pressure terms. The results were also compared with existing experimental and numerical data. It was observed that the finite volume method requires less CPU usage time and yields more accurate results compared to the LBM. It has been noted that the 1st order upwind/SIMPLEC combination converges comparatively quickly with a very high accuracy especially at the boundaries. Interestingly, all variants of FVM discretization/pressure-velocity linking methods lead to almost the same number of iterations to converge but higher-order schemes ask for longer iterations.
    Print ISSN: 1085-3375
    Electronic ISSN: 1687-0409
    Topics: Mathematics
    Published by Hindawi
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  • 4
    Publication Date: 2014-01-01
    Description: This paper addresses erosion prediction in 3-D, 90° elbow for two-phase (solid and liquid) turbulent flow with low volume fraction of copper. For a range of particle sizes from 10 nm to 100 microns and particle volume fractions from 0.00 to 0.04, the simulations were performed for the velocity range of 5–20 m/s. The 3-D governing differential equations were discretized using finite volume method. The influences of size and concentration of micro- and nanoparticles, shear forces, and turbulence on erosion behavior of fluid flow were studied. The model predictions are compared with the earlier studies and a good agreement is found. The results indicate that the erosion rate is directly dependent on particles’ size and volume fraction as well as flow velocity. It has been observed that the maximum pressure has direct relationship with the particle volume fraction and velocity but has a reverse relationship with the particle diameter. It also has been noted that there is a threshold velocity as well as a threshold particle size, beyond which significant erosion effects kick in. The average friction factor is independent of the particle size and volume fraction at a given fluid velocity but increases with the increase of inlet velocities.
    Print ISSN: 2356-6140
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
    Published by Hindawi
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  • 5
    Publication Date: 2014-01-01
    Description: The effect of radiation on laminar and turbulent mixed convection heat transfer of a semitransparent medium in a square enclosure was studied numerically using the Finite Volume Method. A structured mesh and the SIMPLE algorithm were utilized to model the governing equations. Turbulence and radiation were modeled with the RNGk-εmodel and Discrete Ordinates (DO) model, respectively. For Richardson numbers ranging from 0.1 to 10, simulations were performed for Rayleigh numbers in laminar flow (104) and turbulent flow (108). The model predictions were validated against previous numerical studies and good agreement was observed. The simulated results indicate that for laminar and turbulent motion states, computing the radiation heat transfer significantly enhanced the Nusselt number (Nu) as well as the heat transfer coefficient. Higher Richardson numbers did not noticeably affect the average Nusselt number and corresponding heat transfer rate. Besides, as expected, the heat transfer rate for the turbulent flow regime surpassed that in the laminar regime. The simulations additionally demonstrated that for a constant Richardson number, computing the radiation heat transfer majorly affected the heat transfer structure in the enclosure; however, its impact on the fluid flow structure was negligible.
    Print ISSN: 2356-6140
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
    Published by Hindawi
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  • 6
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    Iranian Fisheries Science Research Institute | Tehran, Iran
    Publication Date: 2021-05-19
    Description: The Persian Gulf fisheries are currently managed through regulations that restrict access to the fishery. These controls do not overcome the incentive for over fishing that follows from lack of ownership in open access fisheries. In such situation, there is need more effort to maintain catch and there is overcapitalization in the harvesting sector. ITQ system of fisheries management is increasingly recognized as a practical alternative to regulation. Traditional administration of fisheries as common property has failed to ensure fishery resource management. Wide world fishery management systems are now changing to sustainable utilization. ITQ s are part of this transition. Shrimp fishermen s opinion on the current shrimp management system and changing to a new ITQ system is examined in this study. By using a questionnaire and a stratified random sampling method, a total of 144 fishermen were interviewed in Hormozgan province. Descriptive statistics and contingency tables techniques were used to estimate the agreement of fishermen with ITQ system in the study area. The results indicated that most of fishermen are not agree to change the shrimp management system. Despite the result, it showed that the younger, more experience, higher education and lower income fishermen are most agree to change the current management system than the others . Although the overall result come out significant with ITQ system but it cannot be denied. There is need to comply ITQ system as a new management system to reduce current problems.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Fisheries Management ; Quota ; Shrimp Fishing ; ITQ
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 46pp.
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  • 7
    Publication Date: 2021-05-19
    Description: Feeding habits of three dominant species of tuna fishes (Thunnus tonggol, Thunnus albacares, Euthynnus affinis) and dominant species of sardine (Sardinella sindensis) were investigated from December 2006 to November 2007 in the western waters of Oman Sea. Seasonally samples of three species of these tuna and monthly samples of sardine were collected. Feeding studies on 101 longtail tuna (T.tonggol) indicated that the bony fishes were main food of this species (98.3%) and followed by random foods included cephalopods (1.7%) and crustaceans (1.7%). Among the bony fishes, anchovy (66 %) and sardines (25.9 %) were most important than the other fishes. FI and CV for this species were calculated 26.4 and 21.8 respectively. Stomach content analysis of 85 specimens of E.affinis demonstrated that bony fishes were only food for this species (100%). Sardines (49.3%) and anchovy (11.9%) were foremost food items for E.affinis. Moreover FI and CV were calculated 64.7 and 15.3 correspondingly. The stomach of 120 yellowfin tuna (T.albacares) were analyze. Results showed that bony fishes,cephalopods and crustaceans were formed food items of this species .Yellowfin tuna were preferable fed on bony fishes (87.7%) specially sardines(41.2%),flying fish(13.9%)and M.cordyla(10.4%) and followed by cephalopoda (43.8%) specifically Loligo sp.(84.5%) and crustaceans(11.2%) . FI and CV were calculated 38.3 and 25.8.Study on 320 stomachs were determined that zooplankton and phytoplankton formed food of S.sindensis. Zooplankton (crustacean and molluscs) were main food (90%) and phytoplankton (Bacillariophyceae and Dynophyceae) were least food items (10%). Copepoda (crustaceans) with 58% were preferable food and bivalves and after that bivalves (molluscs) with 14%, Bacillariophyceae (8%) and Cyanophyceae (2%) CV and FI were 30.3 and 29.4 respectively.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Feeding Habits ; Stomach content ; Thunnus albacares ; Thunnus tonggol ; Euthynnus affinis ; Sardinella sindensis ; Species ; Tuna ; Samples ; T.tonggol ; Cephalopods ; Crustaceans ; Anchovy ; Phytoplankton ; Zooplankton
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 124pp.
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  • 8
    Publication Date: 2021-05-19
    Description: One of the most visible direct impacts of fishing is the capture of non-target species, known collectively as bycatch. By-catch includes species that are unwanted and discarded (discards) and species that are retained and sold (byproduct) (Stobutzki et al., 2003). Although tuna purse seine fisheries have been shown to be selective, leading to lower levels of by-catch than other fisheries (Alverson et al., 1994; Kelleher, 2005), several species can be incidentally caught and, in some cases, discarded at sea. These include vulnerable and sensitive species such as turtles, mammals, and sharks (Minami et al. 2007; Romanov, 2008b). Tuna purse seine fisheries probably apply the most intensive direct human impact on the tropical epipelagic ecosystems in all oceans. Because of the worldwide scale of purse seine fisheries, an assessment of their impact on associated and dependent species is essential (Romanov, 2002a).
    Description: Published
    Keywords: Thunnus tonggol ; Thunnus albacares ; Katsuwonus pelamis ; By-catch ; Tuna ; Purse seine ; Identification ; Species
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.239-244
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  • 9
    Publication Date: 2021-05-19
    Description: In this study, the feeding habits of blue swimming crab (Portunus segnis) in the Northeast Persian Gulf were investigated. A total of 722 specimens were collected using bottom trawl. The samples were transferred to the laboratory in order to further analysis after freezing. All individuals were dissected and their stomach was removed. The results showed the vacancy index of stomach (CV) was 34.5. This finding indicated that this species is a gluttonous crab. Also the analysis of their feeding habits showed that this species is carnivorous. The main items included crustaceans, fishes and mollusks. Their diet varied seasonally. Crustaceans were more important in summer whereas fishes and mollusks were more important during autumn and winter, respectively. The crustaceans included shrimps and other crabs. The dominant mollusks were the bivalves such as common name Marcina hiantina, Circentia callipyga, Tellina sp., Cardita bicolor and gastropods Cerithium erythraeonese, Atys sp. There were significant differences in feed items occurrence frequency between sexes.
    Description: Published
    Keywords: Portunus segnis ; Crab ; Feeding ; Stomach ; Habitats
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.646-655
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  • 10
    Publication Date: 2021-05-19
    Description: Biology aspects of cobia (Rachycentron canadum) were investigated from October 2005 to December 2006 in Northern waters of Persian Gulf (Hormozgan province).The reproduction cycle, sexual maturity, sex ratio, Fecundity, Lm50, feeding, length frequency, growth parameters and mortality of cobia were studied from total of 509 specimens ranged from 19 to 159 fork length. Gonadosomatic index peaked during spring and summer with main peak in June. Spontaneous spawning occurs around the year with peak in June. The overall female to male ratio was significantly 1 : 1.49 (P〈0.05). Batch fecundity were estimated 1684954±118990 in 15 females. Relationship between total length and fecundity were calculated F=1.3717TL 2.9567 (r2= 0.82). Feeding studies indicated that the bony fishes were main food of cobia (76%) and followed by crustaceans (25%) and mollusks (11%). Rays were least food items (22%). Maximum and Minimum GaSI were observed in March (33%) and August (0.07%) respectively. Females reached 50% sexual maturity at 81.25 cm TL. The total length -weight relationship was W=0.0042L3.1162 ( r2=0.9852). Thetotal length-fork length relationship was TL= 1.1561FL-2.533 (r2= 0.9933). Growth parameters K, L ,and t0 were calculated by von bertalanfy growth equation : 0.11 (year1), 168.65 cm, 3.49 and -0.97 respectively. The instaneous rate of total mortality (z), natural mortality (M) and fishing mortality estimated by catch curve analysis were 0.30, 0.25, 0.14 (year1). Exploitation rate and Tmax were 0.36 and 28 yearrespectively.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Rachycentron canadum ; Cobia ; Sex ratio ; Fecundity ; Lm50 ; Feeding ; Mortality ; Growth ; Parameters ; Biology ; Maturity ; Spawning ; Fecundity
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 85pp.
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