Artykuły w czasopismach na temat „Semi-Intensive Floating Tank System”
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Rahman, Md Hashibur, Mohammad Mahfujul Haque, Md Nasirul Islam i Md Arifuzzaman. "Growth and production performance of tilapia (Oreochromis niloticus) in intensive and semi-intensive tank based aquaculture system using floating feed". International Journal of Fisheries and Aquatic Studies 9, nr 4 (1.07.2021): 290–96. http://dx.doi.org/10.22271/fish.2021.v9.i4d.2546.
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Partridge, G. J., G. A. Sarre, B. M. Ginbey, G. D. Kay i G. I. Jenkins. "Finfish production in a static, inland saline water body using a Semi-Intensive Floating Tank System (SIFTS)". Aquacultural Engineering 35, nr 2 (sierpień 2006): 109–21. http://dx.doi.org/10.1016/j.aquaeng.2005.09.001.
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Pham, Thanh-Dam, i Hyunkyoung Shin. "The Effect of the Second-Order Wave Loads on Drift Motion of a Semi-Submersible Floating Offshore Wind Turbine". Journal of Marine Science and Engineering 8, nr 11 (30.10.2020): 859. http://dx.doi.org/10.3390/jmse8110859.
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Floating offshore wind turbines (FOWTs) have been installed in Europe and Japan with relatively modern technology. The installation of floating wind farms in deep water is recommended because the wind speed is stronger and more stable. The design of the FOWT must ensure it is able to withstand complex environmental conditions including wind, wave, current, and performance of the wind turbine. It needs simulation tools with fully integrated hydrodynamic-servo-elastic modeling capabilities for the floating offshore wind turbines. Most of the numerical simulation approaches consider only first-order hydrodynamic loads; however, the second-order hydrodynamic loads have an effect on a floating platform which is moored by a catenary mooring system. At the difference-frequencies of the incident wave components, the drift motion of a FOWT system is able to have large oscillation around its natural frequency. This paper presents the effects of second-order wave loads to the drift motion of a semi-submersible type. This work also aimed to validate the hydrodynamic model of Ulsan University (UOU) in-house codes through numerical simulations and model tests. The NREL FAST code was used for the fully coupled simulation, and in-house codes of UOU generates hydrodynamic coefficients as the input for the FAST code. The model test was performed in the water tank of UOU.
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Walia, Daniel, Paul Schünemann, Hauke Hartmann, Frank Adam i Jochen Großmann. "Numerical and Physical Modeling of a Tension-Leg Platform for Offshore Wind Turbines". Energies 14, nr 12 (15.06.2021): 3554. http://dx.doi.org/10.3390/en14123554.
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In order to tap the world wide offshore wind resources above deep waters, cost efficient floating platforms are inevitable. Tension-Leg Platforms (TLPs) could enable that crucial cost reduction in floating wind due to their smaller size and lighter weight compared to spars and semi-submersibles. The continuous development of the GICON®-TLP is driven by computer-aided engineering. So-called aero-hydro-servo-elastic coupled simulations are state-of-the-art for predicting loads and simulating the global system behavior for floating offshore wind turbines. Considering the complexity of such simulations, it is good scientific praxis to validate these numerical calculations by use of scaled model testing. This paper addresses the setup of the scaled model testing as carried out at the offshore basin of the École Centrale de Nantes, as well as the numerical model for the GICON®-TLP. The results of dedicated decay tests of the scaled model are used to validate the computational model at the first stage and to determine the natural frequencies of the system. Besides different challenges to the scaled model during the survey, it was possible to take these difficulties into account when updating the numerical model. The results show good agreements for the tank tests and the numerical model.
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Maslov, V. "Research of freak wave effect on a floating object in seakeeping tank". Transactions of the Krylov State Research Centre 3, nr 397 (6.08.2021): 65–74. http://dx.doi.org/10.24937/2542-2324-2021-3-397-65-74.
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Object and purpose of research. This paper describes physical modeling of interaction process of abnormal wave (freak wave) with a marine floating structure in a seakeeping tank of the Krylov State Research Center. Freak wave is extremely dangerous because of the difference from wind waves by an unusually steep front slope and a gentle trough. Freak wave appears suddenly and collapses rapidly. Research of effect process features is necessary for understanding and analysis of the object behavior at extreme sea conditions. As experiment results it was necessary to obtain empirical data of sea object motions and accelerations at interaction with freak wave on different course angles and speeds. The obtained physical experiment results will be the foundation of theoretical studies and numerical calculation methods. Materials and methods. Physical modeling of the interaction process of freak wave with a marine floating structure was conducted in a deep seakeeping tank. Freak wave was generated by the linear superposition method of four twodimensional unidirectional regular waves with variable steepness in frequency range of 2 to 6 rad/s. To create a control signal was using special software. Wave packets were formed consisting of a sequence of a four harmonicas with a given frequency, height and duration. For parameters registration of freak wave were used string probes installed with a certain step along the length of the tank. A marine floating structure model was fixed by elastic fastening system in a window of a tow cart. For measure the motions of marine floating structure and its accelerations in define points at encounter with freak wave the contactless optic system and two-component acceleration sensors (accelerometers) were used. Cases of structure interaction with freak wave at different course angles and speeds were considered. Main results. As result of physical experimental data of floating structure motions in the interaction with freak wave in conditions of regular sea state at five course angles with speed and without speed were obtained. Dependencies of roll, pitch and heave motions at different course angles and various speeds were built. Similar dependencies of vertical and transverse accelerations on a stem also were built. Comparative analysis of results with data, which were obtained on intensive irregular sea state (spectrum JONSWAP) at identical experiment conditions, and also with foreign results was carried out. Conclusions. The greatest roll and maximum accelerations are registered at alongside position to abnormal wave, but cargo vessel has a sufficient reserve of dynamic stability to withstand such an impulse effect. The values of roll motion and accelerations on irregular sea state are close to the parameters measured at freak wave effect. This similarity is explained by rocking effect of periodic impact of irregular sea state, the proximity of natural period of roll oscillations to average period of waves and sufficiently high waves. In comparison with foreign researches, a wider range of heading angles and speeds is considered, and data about accelerations in a stem are obtained.
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Perdomo, S., C. Bangueses i J. Fuentes. "Potential Use of Aquatic Macrophytes to Enhance the Treatment of Septic Tank Liquids". Water Science and Technology 40, nr 3 (1.08.1999): 225–32. http://dx.doi.org/10.2166/wst.1999.0166.
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In several urban and suburban areas, the problem of the disposal and treatment of septic tank liquids has not been solved yet. This paper deals with the primary operational evaluation of a conventional system of ponds used at Tarariras, in the Department of Colonia, Uruguay, as well as the potential use of aquatic macrophytes to enhance such treatment. The conventional system was sampled over a period of approximately one month at the end of the summer in order to determine the main parameters. Groups of up to 20 samples were studied to determine the normal distributions. Correlation coefficients were obtained for the normal probability plot between 0.84 and 0.99. The most relevant statistical characteristics were calculated for each parameter. The removal efficiency was 80.0% of BOD5, 58.5% of COD, 75.8% of NH4+-N, 9.5% of PO4−3-P and 38.5% of TSS. At the same time, batch and semi-continuous trials were carried out at bench scale with Eichhornia crassipes (floating macrophyte) and Typha latifolia (emergent macrophyte). The best efficiencies were obtained for the latter, with values of 96.6% of BOD5, 93.0% of COD, 99.6% of NH4+-N, 95.2% of PO4−3-P and 95.5% of TSS. It was concluded that constructed wetlands could be the answer to a more complete treatment process.
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Fernandez, Hernan, Gregorio Iglesias, Rodrigo Carballo, Alberte Castro, Marcos Sánchez i Francisco Taveira-Pinto. "OPTIMIZATION OF THE WAVECAT WAVE ENERGY CONVERTER". Coastal Engineering Proceedings 1, nr 33 (9.10.2012): 5. http://dx.doi.org/10.9753/icce.v33.structures.5.
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The development of efficient, reliable Wave Energy Converters (WECs) is a prerequisite for wave energy to become a commercially viable energy source. Intensive research is currently under way on a number of WECs, among which WaveCat©—a new WEC recently patented by the University of Santiago de Compostela. In this sense, this paper describes the WaveCat concept and its ongoing development and optimization. WaveCat is a floating WEC intended for operation in intermediate water depths (50–100 m). Like a catamaran, it consists of two hulls—from which it derives its name. The difference with a conventional catamaran is that the hulls are not parallel but convergent; they are joined at the stern, forming a wedge in plan view. Physical model tests of a 1:30 model were conducted in a wave tank using both regular and irregular waves. In addition to the waves and overtopping rates, the model displacements were monitored using a non-intrusive system. The results of the physical model tests will be used to validate the 3D numerical model, which in turn will be used to optimize the design of WaveCat for best performance under a given set of wave conditions.
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Kasapidou, Eleni, Zoitsa Basdagianni, Vasileios Papadopoulos, Chrysoula Karaiskou, Anastasios Kesidis i Arsenios Tsiotsias. "Effects of Intensive and Semi-Intensive Production on Sheep Milk Chemical Composition, Physicochemical Characteristics, Fatty Acid Profile, and Nutritional Indices". Animals 11, nr 9 (2.09.2021): 2578. http://dx.doi.org/10.3390/ani11092578.
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Dairy sheep farming is a vital sector of the agricultural economy in Greece. Information on the effect of the farming system on sheep milk characteristics is critical for producing dairy products with improved nutritional value according to the current guidelines for healthy food consumption. This study aimed to investigate the basic composition, physicochemical characteristics, fatty acid composition, and nutritional indices of milk produced in intensive and semi-intensive sheep farms. Bulk tank milk samples from 20 intensive and 20 semi-intensive sheep farms were examined. Sheep in the intensive farms were kept indoors and were fed with roughage, silage, and concentrates. Sheep in the semi-intensive farms were kept indoors during the night and were moved to the pastures during the day. Sheep were fed with roughage, silage, and concentrates in combination with grazing. Milk composition and somatic cell count were determined with automatic analyzers. The physicochemical characteristics were determined with standard laboratory methods. The fatty acid composition was analyzed by gas chromatography. The farming system did not affect milk chemical composition and physicochemical characteristics. However, milk fatty acid composition and nutritional value were significantly improved in milk from farms using the semi-intensive production system, and this favorable effect was attributed to the inclusion of pasture in sheep diet.
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Radosavljević, Vladimir, Miroslav Ćirković, Dragana Ljubojević, Dobrila Jakić Dimić, Zoran Marković, Jadranka Žutić i Vesna Milićević. "SEARCHING FOR SOLUTIONS IN AQUACULTURE: AQUAPONICS". Archives of Veterinary Medicine 7, nr 2 (21.01.2015): 71–78. http://dx.doi.org/10.46784/e-avm.v7i2.132.
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Aquaponic production combines intensive production with waste recycling and water conservation. Aquaponic join recirculating aquaculture with hydroponics to use nutrient waste from aquaculture as an input to plant growth. Traditional aquaculture systems treat or dispose nutrient-rich wastewater. In aquaponics, the waste products from the fish are converted by a bio-fi lter into soluble nutrients which are absorbed by the plants, and allow “clean” water to be returned back to the fish. Thus, it produces valuable fish protein with a minimal pollution of fresh water resources, while at the same time producing horticultural crops. Fish in aquaponic production systems can be raised in ponds, tanks, or other containers. Plants are grown separately in hydroponic tanks, submerged in water but suspended in gravel, sand, perlite, or porous plastic films, as well as on floating rafts. Systems vary greatly in design and construction, but most perform the following key functions: finfish and plant production, removal of suspended solids, and bacterial nitrification. This review discusses applications, effects and perspective of aquaponics.
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Wang, Zhen Peng, Ya Ge You, Ya Qun Zhang, Song Wei Sheng i Hong Jun Lin. "Design and Hydrodynamic Performance Testing of One-Base Multi-Buoy Floating Sharp Eagle Wave Energy Converter". Advanced Materials Research 1092-1093 (marzec 2015): 152–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.152.
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Research on wave energy extraction has been conducted in many countries to meet the growing demand for clean energy. To find an efficient and economic way to convert wave energy, an one-base multi-buoy offshore floating Sharp Eagle wave energy converter is designed, consisting of four Eagle head absorbing buoys, one semi-submersible barge, one energy conversion system, buoyancy tanks, underwater appendages and other components. The working principle of the device is described in this paper. To test the hydrodynamic performance of device and make an initial evaluation for the design, a model experiment of 1/13.78th scale was carried out. The influence of wave period, wave height, pressure in hydrocylinders and wave direction is tested. All the efficiencies in different conditions are compared with each other, while the high efficiency and stability of device are verified.
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Borges, Aurélio Ferreira, Anderson Alves Santos, José Luiz Pereira de Rezende, Maria dos Anjos Cunha Silva Borges, Abílio da Paixão Ciríaco i Thaís Muniz Ottoni Santiago. "Environmental performance of aquaculture in Rondônia state, Brazil". Revista Ceres 62, nr 2 (kwiecień 2015): 208–14. http://dx.doi.org/10.1590/0034-737x201562020011.
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The objective of this study was to analyze the environmental performance of aquaculture in the city of Colorado do Oeste, Rondônia State, Brazil. Fifteen fish farmers were interviewed. For data collection, structured interviews were carried out, using a questionnaire based on information supplied by the United Nations Food and Agriculture Organization (FAO). The questionnaire considered 12 items, organized into three main topics: a) social and legal standards b) environmental standards c) standards of food safety and hygiene. The questionnaire considered 12 items, organized into three main topics: a) social and legal standards b) environmental standards c) standards of food safety and hygiene. Aquaculture in the city of Colorado do Oeste, Rondônia presents two fish production systems: extensive and semi-intensive. In the semi-intensive system, stocking rate was one fish per m3, on average; tambaqui (Colossoma macropomum), tilapias (Oreochromis spp.), pirarucu (Arapaima gigas) and pintado (Pseudoplatystoma spp.) were the species farmed at the largest number. The rate of water renewal was due to the greater availability of natural food in this system. Water renewal was constant in the ponds (1,500 liters per minute). In the semi-intensive system using dug ponds, alevins were stocked and fed during the entire rearing time with natural and exogenous food. The extensive system relied on the natural production of the pond, with stocking density limited by the production of natural food. The little renewal of water made the cultivation tank itself acted as a decantation lake, with the occurrence of oxidation and sedimentation of residual organic matter, consisting of feces, debris and organic fertilizer. Production of reduced effluent volume took place in the extensive system, compared to the cultivation area. In addition, there was high water turbidity, caused by high concentration of planktonic organisms, and low concentrations of dissolved oxygen in the water. Data showed that nine estates of the interviewed fish farmers had critical environmental performance (less than 30.0%). Six estates of fish farmers had bad environmental performance (between 30.0 and 50.0%) (Coefficient of sustentainability = green square x 100 ÷ Total Questions less the yellow squares)
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Pasch, Johannes, Samuel Appelbaum, Harry Wilhelm Palm i Ulrich Knaus. "Growth of Basil (Ocimum basilicum) in Aeroponics, DRF, and Raft Systems with Effluents of African Catfish (Clarias gariepinus) in Decoupled Aquaponics (s.s.)". AgriEngineering 3, nr 3 (15.07.2021): 559–74. http://dx.doi.org/10.3390/agriengineering3030036.
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Basil (Ocimum basilicum) was cultivated in three hydroponic subsystems (i) a modified commercial aeroponics, (ii) a dynamic root floating (DRF) system, and (iii) a floating raft system in a decoupled aquaponic system in Northern Germany, Mecklenburg–Western Pomerania. For plant nutrition, aquaculture process water from intensive rearing of African catfish (Clarias gariepinus) was used without fertilizer. After 39 days, 16 plant growth parameters were compared, with aeroponics performing significantly better in 11 parameters compared with the DRF, and better compared with the raft in 13 parameters. The economically important leaf wet and dry weight was over 40% higher in aeroponics (28.53 ± 8.74 g; 4.26 ± 1.23 g), but similar in the DRF (20.19 ± 6.57 g; 2.83 ± 0.90 g) and raft (20.35 ± 7.14 g; 2.84 ± 1.04 g). The roots in the DRF grew shorter and thicker; however, this resulted in a higher root dry weight in aeroponics (1.08 ± 0.38 g) compared with the DRF (0.82 ± 0.36 g) and raft (0.67 ± 0.27 g). With optimal fertilizer and system improvement, aquaponic aeroponics (s.s.) could become a productive and sustainable large-scale food production system in the future. Due to its simple construction, the raft is ideal for domestic or semi-commercial use and can be used in areas where water is neither scarce nor expensive. The DRF system is particularly suitable for basil cultivation under hot tropical conditions.
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Delille, D., i N. Vaillant. "The influence of crude oil on the growth of subantarctic marine bacteria". Antarctic Science 2, nr 2 (czerwiec 1990): 123–27. http://dx.doi.org/10.1017/s0954102090000153.
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The short term degradation of ‘Arabian light’ crude oil was followed under various seasonal conditions in coastal seawater at Iles Kerguelen. Artificial degradation experiments were carried out in 3 m3 tanks. In situ experiments were conducted in free-floating, semi-enclosed chambers permitting direct contact between the crude oil and the marine environment. Daily sampling allowed a regular survey of the bacterial changes of the oil contaminated seawater. All samples were analysed for total bacteria, heterotrophic viable microflora and hydrocarbon utilizing microflora. At the end of experiments, the remaining oil was carefully collected for rough quantitative estimation of hydrocarbon degradation. All the results clearly revealed a significant increase in the three types of bacterial microflora after the addition of crude oil. However, the data suggest that the initial state of the bacterial communities is important. Thus, the seasonal variations in the bacterial responses to hydrocarbon addition can be related to the differences in the natural bacterial populations involved. In all cases the wall effects observed in batch systems were reduced with in situ incubations.
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Tacon, A. G. J., M. J. Phillips i U. C. Barg. "Aquaculture feeds and the environment: the asian experience". Water Science and Technology 31, nr 10 (1.05.1995): 41–59. http://dx.doi.org/10.2166/wst.1995.0363.
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Asia, the birth place of aquaculture, supplies 85% of global aquaculture production and has had a long tradition in the development and use of different dietary feeding strategies, ranging from the use of fertilizers and simple supplementary feed mixtures to the manufacture of ‘water-stable’ pelleted shrimp feeds. The present paper reviews the different aquaculture feeding strategies used within semi-intensive and intensive farming systems in selected Asian countries, and in particular examines their relative impacts upon the aquatic environment. Emphasis is placed on the environmental compatibility and central role played by small scale polyculture-based integrated farming systems in Asian aquaculture, and the need to carefully balance exogenous supplementary feed inputs with the endogenous supply of natural food organisms within semi-intensive pond farming systems. In the case of intensive pond/cage-based farming systems attention is focused on the need to further improve feed formulation, feed manufacture, and on-farm feed and water management so as to maximize feed intake and feed efficiency, and minimize feed wastage and water pollution. Furthermore, in view of the negative experiences of some countries in the region with deteriorating water quality and disease outbreaks within intensive pond/cage-based farming systems, there is an urgent need to improve farm husbandry methods and reduce the current reliance of the aquaculture sector on chemotherapeutants; including limiting the use of the antibiotics only to qualified personnel by developing appropriate Codes of Practice. In this respect there is also a need to recognize the important role played by nutrition in disease resistance. In addition, the paper reviews the legislative controls concerning aquafeed manufacture in selected Asian countries, and highlights the implications of applying government feed legislative controls (i.e. relating to feed composition, feed manufacture, feed efficiency or water pollution) directly from one environmental setting or country to another, and urges countries to develop their own solutions depending upon the farming system employed (i.e. intensive or semi-intensive; tank, cage or pond; coldwater or warmwater; freshwater or seawater), national government policies and priorities, and the resources available to them. In conclusion the paper stresses the key role which can be played by the resident aquafeed manufacturing sector in helping farmers, not only in the provision of feed inputs, but more importantly concerning the management of the feed on the farm and in the use of appropriate environmentally sound husbandry practices; feed manufacturers usually having the closest contact with farmers and in many countries being the only link in the chain between the farmer and the government legislature.
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Abyn, Hassan, Adi Maimun, Jaswar Jaswar, M. Rafiqul Islam, Allan Magee, Behnam Bodaghi, Mohamad Pauzi, C. L. Siow i M. Mobassher Tofa. "Hydrodynamic Interaction of Floating Structure in Regular Waves". Jurnal Teknologi 66, nr 2 (1.01.2014). http://dx.doi.org/10.11113/jt.v66.2491.
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Floating structures play an important role for exploring the oil and gas from the sea. In loading and offloading, motion responses of offshore floating structures are affected through hydrodynamic interaction. Large motions between floating bodies would cause the damage of moorings, offloading system and may colloid to each other. This research studies on hydrodynamic interaction between Tension Leg Platform (TLP) and Semi-Submersible (Tender Assisted Drilling (TAD)) in regular and irregular waves with scenario as follows: fixed TLP and 6-DOF floating semi-submersible and 6-DOF both TLP and semi-submersible. Under these conditions, hydrodynamics coefficients, mooring and connectors forces, motions and relative motions of TLP and Semi-Submersible will be simulated numerically by using 3D source distribution method. As the scope is big, this paper only presents model experiment of floating TLP and semi-submersible in the regular wave. The experiment is carried out in the UTM Towing Tank.
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Rahman, Md Hashibur, i Md Arifuzzaman. "IMPACT OF FLOATING FEED ON GROWTH PERFORMANCE, YIELD AND SURVIVAL OF ROHU (LABEO ROHITA) AND TILAPIA (OREOCHROMIS NILOTICUS) IN TANK BASED INTENSIVE AQUACULTURE SYSTEM". International Journal Biological Innovations 03, nr 02 (2021). http://dx.doi.org/10.46505/ijbi.2021.3208.
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Gonçalves, Rodolfo Trentin, Shinichiro Hirabayashi, Guilherme Vaz i Hideyuki Suzuki. "Force Measurements of the Flow Around Arrays of Three and Four Columns With Different Geometry Sections, Spacing Ratios, and Incidence Angles". Journal of Offshore Mechanics and Arctic Engineering 142, nr 2 (16.11.2019). http://dx.doi.org/10.1115/1.4045212.
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Abstract An experimental campaign for the flow around a stationary array of three and four columns with low aspect ratio, H/L = 1.5, piercing the water free surface, was carried out in a towing tank. These numbers of columns correspond to typical multi-column offshore systems, such as semi-submersibles (SS), tension leg platforms (TLPs), and floating offshore wind turbines (FOWTs). Three parameters were investigated: the spacing ratio between column centers (from two up to four characteristic lengths), current incidence angles, and column section geometries (circular, square, and diamond). The Reynolds number of the experiments was 100,000. Forces were measured in each column using a three degrees-of-freedom load cell, and results of lift and drag forces were presented for each column separately and the whole system. The results of mean and standard deviation of forces were assessed using a statistical uncertainty analysis procedure for finite length measurements’ signals. This methodology not only assesses the quality of the experimental data but also facilitates validation of numerical tools. The objectives of the current work were therefore manifold: to better understand the influence of the relative position, shape, and incidence angle on multi-column offshore structures; to create a reliable database for computational fluid dynamics (CFD) validation; and to prepare the path to flow-induced motions (FIMs) experimental and numerical work of free-moving multi-column offshore systems.
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Rahman, Md Hashibur, i Md Nasirul Islam. "Sinking Feed Efficiency in Growth Performance, Feed Conversion Ratio (FCR) and Yield of Tilapia (Oreochromis niloticus) at Different Stocking Densities". Asian Journal of Fisheries and Aquatic Research, 14.09.2021, 1–26. http://dx.doi.org/10.9734/ajfar/2021/v14i530305.
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The efficiency of feed is considered as one of the most crucial factors that affects the growth performance, feed conversion ratio and yield as well. The study was aimed to compare the growth parameters of tilapia at different stocking densities to detect the efficiency of sinking feed assessing the growth trends at various sampling stages. To evaluate the comparative yield, the study was carried out in twelve concrete tanks under an outdoor laboratory shed. Tilapia (Oreochromis niloticus) fry was released at the rate of 8 fry per tank as per the recommended stocking density of 320 fishes/decimal and 4 fry per tank equivalent to the stocking density of 160 fishes/decimal in intensive and semi-intensive aquaculture system, respectively. To evaluate the growth trends sinking feed was used for feeding the fish during the experimental period for T1 (Intensive) and T2 (Semi-intensive), respectively. The feed was supplied in each with three replications at the rate of 20%, 15%, and 10% of the body weight of fish, respectively. The daily ration of feed was delivered to fish dividing into two parts daily. Aeration facilities using air stone aerator were installed for 24 hours. To assume the consecutive growth trends, weight of fish was recorded in 3 days interval to have better understanding on the yield performance in relation to the feed conversion ratio (FCR). Water quality parameters i.e., temperature and dissolved oxygen (DO) were recorded two times daily. The final weight gains of fish were 133.77±5.65 gm and 50.70±2.40 gm for T1 and T2, respectively. The mean percent weight gain of tilapia was higher in T1 (1127.25±0.00) than T2 (518.51±0.00 gm). Feed conversion ratio (FCR) in T1 and T2 were 1.97±0.11 and 1.70±0.07, respectively. The specific growth rates (SGR) of tilapia in T1 4.90±3.03 and 4.78±3.83 considering the data at the beginning and the end of the production cycle, respectively. Higher total production was obtained in T1 (1070.19 gm) than T2 (610.00 gm) with 100% survival in both the treatments. The present study reveals that, the efficiency of sinking feed was higher in T1 than T2 and farmers might be suggested to practice tank-based intensive aquaculture system to get higher production in a short period of time.
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Zhao, Yuliang, i Sheng Dong. "Long-term extreme response analysis for semi-submersible platform mooring systems". Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 7.12.2020, 147509022097651. http://dx.doi.org/10.1177/1475090220976515.
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The accurate assessment of long-term extreme responses of floating-structure mooring system designs is important because of small failure probabilities caused by long-term and complex ocean conditions. The most accurate assessment would involve considering all conceivable sea states in which each sea state is regarded as a stochastic process and performing nonlinear time-domain numerical simulations of mooring systems to estimate the extreme response from a long-term analysis. This procedure would be computationally intensive because of the numerous short-term sea states involved. Here, a more feasible approach to evaluate the long-term extreme response is presented through immediate integration combined with Monte Carlo simulations. A parameter fitting procedure of the short-term extreme response distribution under irregular wave conditions is employed to solve the long-term response integration. Case studies were conducted on a semi-submersible platform using environmental data measurements of the Gulf of Mexico and a joint distribution model of the environmental parameters was considered. This approach was observed to be effective and the results were compared with those of traditional methodologies (univariate extreme value design and environmental contour methods). The differences were reflected using a reliability analysis of mooring lines, which indicated that the design standards must be stricter when using long-term analysis.
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Wolff Ferreira, Milena, Ricardo Martins Santos, Alanderson Rodrigues da Silva, Sarah Saory Makimoto, Guilherme Ribeiro Capibaribe Barbosa i Gisele Braziliano de Andrade. "Mortality in Pacus (Piaractusmesopotamicus) caused by Pantoeaagglomerans and Pseudomonas aeruginosa in Excavated Tank". Acta Scientiae Veterinariae 47 (20.03.2019). http://dx.doi.org/10.22456/1679-9216.90826.
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Background:Fish production in Brazil is growing strongly. This growth is being mainly driven by mainland aquaculture, which in 2017 produced 691.700 tons of fish. Toimprove production levels, fish farms have become increasingly intensive, but in these systems, the high fish densities in the ponds, the high feeding rate, and the high organic matter levels in the water can lead the fish becoming stressed. This can cause bacterial proliferationand an increase in mortality. Most species of fish-causing bacteria are saprophytes. They are found naturally in the environment and are usually responsible for secondary or opportunistic infections.Thisstudy reports on an outbreak of Pacus (Piaractusmesopotamicus) mortality at an intensive fish farm, in the municipality of Campo Grande, MS, Brazil,that used excavated tanks.Cases:The outbreak occurred at a fish farm in the municipality of Campo Grande, MS, during August, 2015. A total of 200 pacus in two tanks died after they showedthe following symptoms: lethargy, anorexia, increased mucus production, and disordered swimming and water surface searching. The temperature and dissolved oxygen were measured using a digital thermometer and an oximeter, respectively, and water transparency was measured with a Secchi disc. The pH was measured usinga portable digital potentiometer. The values for the water quality parameters analyzed during the mortality period were temperature, 22.5oC; transparency, 20cm; oxygen dissolved in the early morning 3mg/L and at the end of the afternoon, 4.5mg/L; pH 8.3; and toxic ammonia, 0.002ppm. Five fishes were collected from the tank, immediately cooled to 4°C, and sent to the Microbiology and Pathology Laboratories to perform the microbiological and pathological laboratory procedures.After the replication process, the slow glucose fermentation characteristics in MacConkey Agarand other biochemical tests showed that the lactose non-fermenter bacterium was Pseudomonas aeruginosa and the fermenting bacterium was Pantoeaagglomerans. A necroscopic examination revealed congestion of viscera in general and thickening of the gills; the histopathological examination showed an intense inflammatory reaction in the gills; andthe liver showed congestion and dilation of the central, hepatoportal, and sinusoidal veins,marked cytoplasmic vacuolization, the presence of hemosiderin and leukocytosis, and coagulation necrosis and cholestasis foci.Discussion:The water temperature in the tanks (22.5°C) was lower than what is considered ideal for tropical fish. It ranged from 25 to 32°C. Furthermore,the pH (8.3) was close to the limit of what is considered appropriate. The mean tank flow rate at the time of death was 15 L/min, corresponding to a daily renewal rate of 1.2%, which was lower than the 10% per day recommended as the ideal ratefor excavated ponds in a semi-intensive production system. The decreased water flow in the tank during the period when mortality was recorded caused an increase in the amount of accumulated organic matter. This rise is commonly referred to as eutrophication, which is characterized by an increase in the rate of decomposition and release of nutrients into the water. The excess nutrients, mainly nitrogen and phosphorus, cause excessive phytoplankton and aquatic macrophyte growth, which results in a significant reduction in the amount of dissolved oxygen, particularly during periods of low photosynthetic activity.In this case study, the cause of the fish mortalitywas attributed to opportunistic infection by Pantoeaagglomeransand Pseudomonas aeruginosacaused by imbalances in water quality.