scholarly journals DAMPING EFFECT OF FLOATING BREAKWATER TO WHICH ANTI-ROLLING SYSTEM IS APPLIED

1966 ◽  
Vol 1 (10) ◽  
pp. 62
Author(s):  
Juichi Kato ◽  
Seiya Hagino ◽  
Yukio Uekita
Keyword(s):  
Water Surface ◽  
Sea Water ◽  
Natural Oscillation ◽  
Oscillation Period ◽  
Floating Body ◽  
Fishing Ground ◽  
Water Volume ◽  
Fish Farms ◽  
Damping Effect ◽  
Floating Breakwater

Among the recent problems in the fisheries in Japan, the development of fish farms is getting to be important. The breakwater for fish farms is required to have the functions of exchanging sea water and the preservation of fishing ground, as well as the outer facilities of finning ground.. Various types of breakwater to meet the requirements can be considered,the floating breakwater being one of them. When we limit the studies in the wave damping effect of a mobile breakwater, we can summarise that an effective floating breakwater should have sufficient draught under water surface and should have a comparatively large displaced water volume. In other words, the natural oscillation period of the floating body must be large enough as compared with that of the incident wave. (R. L.Wiegel '64) (K. Horikawa et al. '64) for practical purposes the studies on the shape and type must follow. However, if a floating breakwater is provided with a mechanism for attenuating wave, the above-mentioned criterion for the effectiveness must be largely changed.

scholarly journals A conceptual model of flow to the Waikoropupu Springs, NW Nelson, New Zealand, based on hydrometric and tracer (<sup>18</sup>O, Cl,<sup>3</sup>H and CFC) evidence

2008 ◽  
Vol 12 (1) ◽  
pp. 1-19 ◽  
Author(s):  
M. K. Stewart ◽  
J. T. Thomas
Keyword(s):  
New Zealand ◽  
Flow Model ◽  
Sea Water ◽  
Quantitative Description ◽  
Water Volume ◽  
Deep Aquifer ◽  
Submarine Springs ◽  
Recharge Sources ◽  
Flow Systems ◽  
New Evidence

Abstract. The Waikoropupu Springs, a large karst resurgence 4 km from the coast, are supplied by the Arthur Marble Aquifer (AMA) underlying the Takaka Valley, South Island, New Zealand. New evidence on the recharge sources in the catchment, combined with previous results, is used to establish a new recharge model for the AMA. Combined with the oxygen-18 mass balance, this yields a quantitative description of the inputs and outputs to the aquifer. It shows that the Main Spring is sourced mainly from the karst uplands (74%), with smaller contributions from the Upper Takaka River (18%) and valley rainfall (8%), while Fish Creek Spring contains mostly Upper Takaka River water (50%). In addition, much of the Upper Takaka River contribution to the aquifer (58%) bypasses the springs and is discharged offshore via submarine springs. The chemical concentrations of the Main Spring show input of 0.5% of sea water on average, which varies with flow and derives from the deep aquifer. Tritium measurements spanning 40 yr, and CFC-11 measurements, give a mean residence time of 8 yr for the Main Spring water using the preferred two-component model. Our conceptual flow model, based on the flow, chloride, oxygen-18 and age measurements, invokes two different flow systems with different recharge sources to explain the flow within the AMA. One system contains deeply penetrating old water with mean age 10.2 yr and water volume 3 km3, recharged from the karst uplands. The other, at shallow levels below the valley floor, has much younger water with mean age 1.2 yr and water volume 0.4 km3, recharged by Upper Takaka River and valley rainfall. The flow systems contribute in different proportions to the Main Spring, Fish Creek Springs and offshore springs. Their very different behaviours, despite being in the same aquifer, are attributed to the presence of a diorite intrusion below the surface of the lower valley, which diverts the deep flow towards the Waikoropupu Springs and allows much of the shallow flow to pass over the intrusive and escape via submarine springs.

scholarly journals Innovative Biotechnology of Artificial Reproduction of Fish Populations

2020 ◽  
Author(s):  
П.Е. Гарлов
Keyword(s):  
Pituitary Gland ◽  
Sea Water ◽  
Natural Populations ◽  
Ecological Factors ◽  
Water Supply Systems ◽  
Artificial Reproduction ◽  
Fish Farms ◽  
Commercial Fish ◽  
Fish Breeding ◽  
Critical Salinity

С целью повышения эффективности искусственного воспроизводства популяций ценных видов рыб разработаны новые методы управления их размножением, выживаемостью и ростом, которые представлены в виде изобретений. Для управления размножением производителей разработаны методы стимуляции и задержки полового созревания производителей осетровых и костистых рыб. Для стимуляции полового созревания были разработаны препараты изолированной передней и изолированной задней долей гипофиза. Их внедрение в осетроводстве позволило повысить степень их рыбоводного использования в среднем на 15% и достичь экономии гипофиза до 40%. Для задержки полового созревания производителей разработан метод их промышленного резервирования в среде критической солёности 4–8‰, причём как в морской воде, так и в растворах поваренной соли. Производственными испытаниями доказана возможность сохранения рыбоводного качества производителей и получения доброкачественного потомства в этой среде при верхних нерестовых температурах в течение производственно необходимых сроков. С целью заводского воспроизводства природных популяций промысловых рыб разработан метод управления их размножением триадой адекватных экологических факторов ‒ «критической» солёностью, температурой и освещённостью при видоспецифических пороговых воздействиях. На этой основе разработан полносистемный метод воспроизводства популяций ценных видов промысловых рыб (севрюги и Балтийского лосося), охватывающий все этапы заводской биотехники. Новый метод осуществляется путём массовой морской заготовки производителей, получения потомства в морских садках и, после заводского речного выращивания молоди до готовности к миграции, конечного доращивания в морских садках крупной жизнестойкой молоди. Для промышленного внедрения всей предложенной биотехники и круглогодичной аквакультуры разработаны системы водоснабжения рыбоводных заводов и рыбоводных хозяйств на основе внесезонного подземного гидрокондиционирования среды выращивания и на природно-промышленных принципах инженерной экологии. In order to increase the efficiency of artificial reproduction of populations of valuable fish species new methods for managing their reproduction, survival and growth have been developed, which are presented in the form of inventions. To control the reproduction of producers methods have been developed to stimulate and delay puberty of sturgeon and bony fish producers. To stimulate puberty preparations for the isolated anterior and isolated posterior lobes of the pituitary gland have been developed. Their introduction in sturgeon breeding made it possible to increase the degree of their fish farming use by an average of 15% and to achieve a pituitary gland economy of up to 40%. To delay the puberty of producers, a method for their industrial reservation in an environment of critical salinity of 4–8‰ has been developed both in sea water and in solutions of sodium chloride. Production tests have proven the possibility of preserving the fish-breeding quality of producers and obtaining benign offspring in this environment at the upper spawning temperatures during the production required periods of time. With the aim of factory reproduction of natural populations of commercial fish a method has been developed to control their reproduction by a triad of adequate ecological factors – “critical” salinity, temperature and illumination under species-specific threshold effects. On this basis a full-system method of reproducing populations of valuable species of commercial fish (stellate sturgeon and Baltic salmon) has been developed covering all stages of factory biotechnology. The new method is carried out by mass marine harvesting of producers obtaining offspring in sea pens and after the factory river rearing of hatchling until ready for migration the final rearing of large viable juveniles in sea pens. For the industrial introduction of all the proposed biotechnics and year-round aquaculture, water supply systems for fish breeding plants and fish farms were developed on the basis of off-season underground hydroconditioning of the growing environment and on the natural and industrial principles of engineering ecology.

scholarly journals CHARACTERISTICS OF UHF WAVES DISTRIBUTION IN LAND AND WATER SURFACE TROPOSPHERIC WAVEGUIDE

2019 ◽  
pp. 115-121
Author(s):  
Oxana Vladimirovna Kalambatskaya ◽  
Oleg Nickolaevich Pishchin
Keyword(s):  
Communication Systems ◽  
Water Surface ◽  
Sea Water ◽  
Systems Design ◽  
Cellular Communication ◽  
Effect Of Temperature ◽  
Radio Waves ◽  
Wave Direction ◽  
Surface Atmospheric Layer ◽  
Cellular Communication Systems

The article considers examples of ultra-long propagation of UHF radio waves in mobile cellular communication systems. The phenomena are mainly observed in the Astrakhan region in the spring-summer period (May-June) and are presumably associated with sharp seasonal changes of air temperature followed by rains. The effect of temperature inversion results in changing the refraction index in the surface layer and, as a result, in changing the wave direction as the effect of superrefraction in the surface atmospheric layer. The properties of radio waves in their propagation in the land and sea-water surface waveguide are investigated. The values of the heights of land and sea-water surface tropospheric waveguides for cellular communication systems of different ranges are obtained. The features of existing of tropospheric land and sea-water surface tropospheric waveguides are described. The need to use their properties in the mobile communication systems design is stated.

scholarly journals NURSERY TECHNIQUES WITH JUVENILE CORAL TROUT, Plectropomus leopardus WITH DIFFERENT TYPES OF FOOD

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Anak Agung Alit ◽  
Ketut Maha Setiawati ◽  
Tony Setia Dharma
Keyword(s):  
Sea Water ◽  
Survival Rates ◽  
Critical Factor ◽  
Water Volume ◽  
Design Data ◽  
Feeding Method ◽  
Growth And Survival ◽  
Coral Trout ◽  
Juvenile Coral ◽  
Trash Fish

ABSTRACT Feed management is a critical factor in the nursery activities because food serves as an energy for growth and survival rates. The study aimed to determine the best feeding to improve growth and survival rates. Cultured of coral trout grouper seeds were used for this research in 9 fiber tubs each of  0.8 tonnes of sea water volume with 3 treatments and 3 replicates. The feeding treatments were (a) commercial feeding pelle; (b) trash fish; and (c) feeding combinations (50% pellets and 50% trash fish). The initial length of coral trout grouper seeds were 3 cm long. The pellet used was a commercial pellet with dose of 5-10% biomass, while the trash fish was clupeid fish. Feeding times were twice a daya at 08:00 and 16:00 local time. A complete random design was used as an experiment design. Data was analysed using ANOVA and descriptive statistics. Water qualities during larva rearing included water temperature, pH, salinity, DO, ammonia, nitrite, and phosphate. The results showed that growth dan survical rates was significantly affected by combination feeding method (50% pellet and 50% trash fish) with growth rate of 0.08% cm/day and survival rate of 60.20±2.34%. Keywords: Feed, trash fish, juvenile coral trout grouper, growth, and survival.

scholarly journals O limite marítimo do estuário do Sado a partir de imagens satelitais

Finisterra ◽  
2012 ◽  
Vol 30 (59/60) ◽  
Author(s):  
Eugénia Albergaria Moreira
Keyword(s):  
Bottom Sediments ◽  
Water Surface ◽  
Sea Water ◽  
Data Classification ◽  
Landsat Data ◽  
Delta Front ◽  
Water Turbidity ◽  
Estuary Mouth ◽  
Multispectral Data ◽  
Sado Estuary

SEA-SIDE LIMIT OF SADO ESTUARY IN LANDSAT IMAGERIES - The outside limit of Sado estuary corresponds to the submarine delta front, with an arcuate and digitate contour. It was individualised on the MSS Landsat data imageries. Multispectral data classification allowed to verify that the turbidity-plum of Sado estuary mouth rather corresponds to the low-sea-water surface associated to the brightness of the bottom sediments, that to the water turbidity content.

Experimental Study on Water Damping Effects of Hybrid Floating Structure

2013 ◽  
Author(s):  
Youn-Ju Jeong ◽  
Young-Jun You ◽  
Du-Ho Lee ◽  
Min-Su Park
Keyword(s):  
Natural Frequency ◽  
Hybrid Model ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Oscillation Period ◽  
Floating Body ◽  
Small Scale ◽  
Floating Structure ◽  
Damped System ◽  
Damping Effects

In this study, in order to evaluate water damping effects of hybrid pontoon system with cylinders, experimental studies were carried out. At first, in order to evaluate oscillatory motions, three small-scale models of hybrid, tapered, and pontoon were fabricated and tested under the still-water condition. Four acceleration gauges were attached on the top edges and acceleration of top edge were measured during the oscillation. Then, oscillatory motions of oscillation period and stabilizing time to steady-state were analyzed. Finally, based on the oscillatory motions, damping properties of the logarithmic decrement, damping ratio, and natural frequency of damped system were calculated and compared with each other. As the results of this study, it was found that hybrid model presented about 3.67 times higher decay rate of amplitude of the oscillatory motion than the pontoon model. Also, hybrid model presented about 3.67 times higher damping ratio than the pontoon model. Whereas the natural frequency of the pontoon and tapered model were nearly same with the natural frequency of undamped system, that of the hybrid model presented some difference with the that of the undamped system. In addition, periods of floating body at the wet mode presented about 1.5∼3.0 times longer periods than the dry mode, and it was expected that there was not possibility for the resonance. Therefore, it was expected that the hybrid model of this study should contribute to improve serviceability and safety of offshore floating structures as decreasing oscillatory motions.

Characteristics of OWC Type WEC Dampers Installed on a Very Large Floating Structure

2020 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shoichiro Furuya ◽  
Yasuhiro Aida ◽  
Koichi Masuda ◽  
Hiroaki Eto
Keyword(s):  
Wave Energy ◽  
Sea Water ◽  
Prediction Method ◽  
Hydrodynamic Performance ◽  
Floating Body ◽  
Hydrodynamic Characteristics ◽  
Linear Potential ◽  
Floating Structure ◽  
Combined System ◽  
Floating System

Abstract Oscillating water column (OWC) type wave energy converters (WECs) have been researched and developed. OWC WECs are relatively friendly to maintain them in operation because all of mechanical units are set above a sea water surface. In addition, a feature of an OWC device is similar to an air dumper system. Thus, it should be possible not only to harvest wave energy but also to reduce motion of a floating system at the same time. As well as WEC system should be used with other ocean renewable energies as a combined system. This paper describes hydrodynamic characteristics of OWC devices and wave fields around them of multi-OWC devices equipped large floating structures. For this research, the linear potential theory based in-house programme code was applied to calculate hydrodynamic performance of OWC regions and elastic motion behaviours of the structures. Besides, calculation results were compared with some experimental results of characteristics of OWC devices on reference papers published. Then we proved validity of the calculation method. We have quantitatively summarized how much the reduction effect can be seen according to the aircushion placement and the number of aircushions on the floating body. the paper investigated arrangement of OWC devices on the floating structure with several variations. Using the prediction method, effects of arrangement of OWC devices on the performances are investigated.

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