scholarly journals Seasonal and interannual production of sea lettuce ( Ulva sp.) in outdoor cultures based on commercial size ponds

2021 ◽  
Author(s):  
José A. Zertuche‐González ◽  
Jose M. Sandoval‐Gil ◽  
Laura K. Rangel‐Mendoza ◽  
Alberto I. Gálvez‐Palazuelos ◽  
José M. Guzmán‐Calderón ◽  
...  
Keyword(s):  
Commercial Size ◽  
Outdoor Cultures

Decay Heat Characterization for the European Sodium Fast Reactor

2021 ◽  
Author(s):  
Antonio Jiménez-Carrascosa ◽  
Nuria Garcia Herranz ◽  
Jiri Krepel ◽  
Marat Margulis ◽  
Una Baker ◽  
...  
Keyword(s):  
Fast Reactor ◽  
State Of The Art ◽  
Nuclear Data ◽  
Summation Method ◽  
Heat Power ◽  
Coupled Transport ◽  
Decay Heat ◽  
Sodium Fast Reactor ◽  
Detailed Assessment ◽  
Commercial Size

Abstract In this work a detailed assessment of the decay heat power for the commercial-size European Sodium-cooled Fast Reactor (ESFR) at the end of its equilibrium cycle has been performed. The summation method has been used to compute very accurate spatial- and time-dependent decay heat by employing state-of-the-art coupled transport-depletion computational codes and nuclear data. This detailed map provides basic information for subsequent transient calculations of the ESFR. A comprehensive analysis of the decay heat has been carried out and interdependencies among decay heat and different parameters characterizing the core state prior to shutdown, such as discharge burnup or type of fuel material, have been identified. That analysis has served as a basis to develop analytic functions to reconstruct the spatial-dependent decay heat power for the ESFR for cooling times within the first day after shutdown.

Development, operational experience and implications for future design of fast reactors in Western Europe

1990 ◽  
Vol 331 (1619) ◽  
pp. 367-380
Keyword(s):  
Fast Reactor ◽  
Western Europe ◽  
Development Programme ◽  
Operational Experience ◽  
Zero Energy ◽  
Small Power ◽  
Construction Companies ◽  
Future Design ◽  
The Past ◽  
Commercial Size

Over the past 30 years, the partners now collaborating in Europe on fast-reactor development have taken the technology from a theoretical possibility to an engineering reality. In that time there has been a progression from experimental zero energy facilities followed by small power-producing engineering test reactors, to prototype reactors and a large commercial-size reactor. The paper describes the highlights of the reactor programmes in the partner countries and by example illustrates the experience gained from reactor operation and some of the principal activities in the supporting development programme. These include such topics as fuel performance, fast-neutron physics, liquid-metal thermal hydraulics, sodium chemistry, instrumentation and safety aspects. The paper concludes by summarizing some of the main objectives of the current development programme, which is directed to the support of the European Fast Reactor design being prepared by the European design and construction companies.

Seasonal and Geographic Variation in the Species Composition and Size of Prey Consumed by Grey Seals (Halichoerus grypus) on the Scotian Shelf

1993 ◽  
Vol 50 (8) ◽  
pp. 1768-1778 ◽  
Author(s):  
W. D. Bowen ◽  
J. W. Lawson ◽  
B. Beck
Keyword(s):  
Atlantic Cod ◽  
Halichoerus Grypus ◽  
Scotian Shelf ◽  
Sand Lance ◽  
Atlantic Mackerel ◽  
Relative Contribution ◽  
Wet Weight ◽  
The Mean ◽  
Silver Hake ◽  
Commercial Size

The grey seal (Halichoerus grypus) population on the Scotian Shelf has grown significantly over the past 20 yr, thus increasing the potential for competitive interactions between grey seals and fisheries. The relative contribution (percent wet weight) and size of prey eaten were estimated from otoliths and squid beaks recovered from 143 stomachs that contained food of the 528 collected from 1988 to 1990. Although 22 taxa were found, only four species (Atlantic herring, silver hake, Atlantic cod, and squid) accounted for 80% of the estimated weight of food eaten. The mean length of prey eaten ranged from 19 to 35 cm for six species. Only 17% of the cod and none of the pollock and squid eaten were of the length taken in commercial fisheries. However, about 80% of the silver hake and herring eaten were of commercial size. Offshore at Sable Island, northern sand lance, silver hake, and squid (in order of importance) accounted for 86.1% of the wet weight ingested by seals during summer; sand lance and cod accounted for 96.1% of prey eaten in winter. At inshore locations, herring, cod, and pollock made up 90% of the diet in summer; Atlantic mackerel, cod, squid, and herring made up 83% of the diet in winter.

scholarly journals Hyper-intensive farming white shrimp Litopenaeus vannamei (Decapoda: Penaeidae) in a seawater tank under semi-controlled conditions

2013 ◽  
Vol 5 (1) ◽  
pp. 69-74
Author(s):  
A. A. Ortega-Salas ◽  
L. A. Rendón M.
Keyword(s):  
Litopenaeus Vannamei ◽  
Maximum Likelihood Method ◽  
High Density ◽  
White Shrimp ◽  
Likelihood Method ◽  
Food Conversion ◽  
High Density Culture ◽  
Intensive Farming ◽  
Controlled Conditions ◽  
Commercial Size

Shrimp development to a commercial size in high density culture saves food and avoids predators and disease. Our study was conducted to calculate the growth of white shrimp Litopenaeus vannamei by hyper-intensive cultivation under semi-controlled conditions. We seeded at a density of 550 shrimp per m3 during the first cycle and 400 shrimp per m3 in the second cycle in an outdoor tank of 6m3or 6m2 covered with mesh, constant aeration. The shrimp were fed Artemia franciscana during the first two weeks and camaronina pellets (35% protein) as required, in food baskets, aftterwards. The temperature ranged from 22,3 to 31,3°C, pH 7,5-8,7, oxygen 4,26±1,43. The tanks are siphoned of debris every other day, and water was replaced according to a program. The food conversion ratio (FCR) was 1:1,3. The shrimp were measured weekly to calculate growth with the Bertalanffy model. Survival in the first cycle was 95,8 ( 97,9% for the second cycle). Population parameters (maximum likelihood method) for the first cycle were k=0,0301, L∞ =322,16 and t0 =-0,8852; second cycle: k=0,0203, L∞ =294,42 and t0 =-5,3771. There was rapid growth during the first 10 weeks. Biomass was 27kg for the first cycle (second: 16kg). KEY WORDSGrowth, high density, survival, biomass, semi-controlled conditions. 

scholarly journals Square-mesh codend circumference and selectivity

2009 ◽  
Vol 66 (3) ◽  
pp. 566-572 ◽  
Author(s):  
Matt K. Broadhurst ◽  
Russell B. Millar
Keyword(s):  
Mesh Size ◽  
Optimal Configuration ◽  
Marine Science ◽  
Future Studies ◽  
Size Classes ◽  
Scale Assessment ◽  
Posterior Section ◽  
Wide Scale ◽  
Simultaneous Comparisons ◽  
Commercial Size

Abstract Broadhurst, M. K., and Millar, R. B. 2009. Square-mesh codend circumference and selectivity. – ICES Journal of Marine Science, 66: 566–572. Despite the wide-scale assessment and the use of square-mesh codends in demersal trawls, relatively few studies have tested the effects of configurations other than mesh size on their selectivity. We investigated the consequences of increasing the circumference of square-mesh codends used in an Australian penaeid fishery from the expected optimal configuration of ∼33% of maximum diamond-mesh extension to ∼56 and 75%. Three square-mesh designs comprised 27-mm polyamide mesh throughout and had the same length (100 bars, B), but different circumferences (90, 150, and 200 B, respectively). Paired simultaneous comparisons (using twin trawls) of each treatment codend against a small-meshed control revealed significant effects of circumference on the efficiency of the trawl for a small teleost (pink-breasted siphonfish, Siphamia roseigaster) and commercial size classes of school prawns (Metapenaeus macleayi). Compared with the 90 codend, pink-breasted siphonfish catches and prawn count (numbers per 500 g) were both significantly greater in the codends of larger circumference, and these effects are attributed to concomitant (i) convoluted or reduced lateral openings of meshes and (ii) lesser probabilities of organisms encountering meshes in the posterior section. These differences would not preclude the use of codends of larger circumference in the fishery, but they do highlight the need to select appropriate configurations in future studies to reduce the potential for including the confounding effects of different geometries.

scholarly journals Impact of Feed Rations on Growth, Selected Body Parameters and Maturation of Vendace, Coregonus Albula L., Reared in RAS

2014 ◽  
Vol 22 (2) ◽  
pp. 145-150
Author(s):  
Bożena Szczepkowska ◽  
Mirosław Szczepkowski ◽  
Iwona Piotrowska
Keyword(s):  
Growth Rates ◽  
Sexual Maturity ◽  
Fish Growth ◽  
Coregonus Albula ◽  
Body Weights ◽  
Intensive Rearing ◽  
Mature Fish ◽  
Final Survival ◽  
Body Parameters ◽  
Commercial Size

Abstract Vendace, Coregonus albula L., was reared to commercial size in a recirculating system. Three different feed rations were applied during the ten-month-long experiment. The feed rations impacted fish growth rates, and fish in the different groups achieved body weights of 26.6 g to 57.5 g. The final survival in all groups was similar from 44.3% among the fish fed the smallest feed ration to 53.2% in the group receiving the largest feed ration. No differences were noted in the share of viscera, peritoneal fat, or in the hepatosomatic indexes, but there were differences in the gonadosomatic indexes. After thermal stimulation, only males achieved sexual maturity. The number of mature fish was similar in all groups and ranged from 17.8 to 21.3% of all fish. The results of the present study indicated that vendace can achieve commercial size in an intensive rearing period of ten months in RAS.

Solar Fixation of Atmospheric Nitrogen

2004 ◽  
Vol 126 (1) ◽  
pp. 626-632 ◽  
Author(s):  
Michael Epstein ◽  
Rudi Bertocchi ◽  
Jacob Karni
Keyword(s):  
Residence Time ◽  
Atmospheric Nitrogen ◽  
The Novel ◽  
Test Results ◽  
Hot Air ◽  
Economical Benefit ◽  
Fixation Reaction ◽  
Solar Receiver ◽  
Kinetics Of ◽  
Commercial Size

The thermal fixation of atmospheric nitrogen is explored, using a recently developed concept of a particle-seeded solar receiver. The thermodynamics and the kinetics of the formation of nitric oxide (NO) in air at temperatures of about 2300 K are analyzed, and the required residence time and the time to reach the steady state of the reaction between nitrogen and oxygen are calculated. The novel particle-seeded receiver concept is briefly described. The adaptation of the particle-seeded receiver to the fixation reaction in terms of heating rate of the air and residence time is validated based on previous test results and complementary calculations. A proposed method where the solar receiver/reactor is simultaneously coupled with power production, using the exhausted hot air from the reactor to generate electricity, is described. This concept can definitely increase the economical benefit of the process and, thus, its potential attractiveness. Some illustrative figures for a commercial size system are provided.

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