scholarly journals Research of velocity field in vessel’s wake current from «side by side» mooring

2020 ◽  
Author(s):  
Е.Ю. Чебан ◽  
Д.В. Никущенко ◽  
О.В. Мартемьянова ◽  
Н.Е. Зотова
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Fluid Velocity ◽  
Fluid Flows ◽  
Relative Displacement ◽  
Water Area ◽  
Hull Form ◽  
Sensor Field ◽  
Flow Velocity Measurement ◽  
Hull Forms

В настоящей работе приведены результаты исследования полей скоростей, возникающие при обтекании потоком жидкости судов в счале в зависимости от формы корпуса судов, расстояния между ними и относительного смещения корпусов судов лабораторными, натурными и численными методами. Лабораторные эксперименты выполнялись с применением ADV-датчика. Натурные эксперименты проводились на акватории р. Волга с двумя танкерами. Для численного моделирования использовался программный комплекс FineMarineTM. Выполненное сопоставление результатов измерений скорости потока различными методами, показало достаточную сходимость результатов. Получено, что для моделей судов с упрощенными обводами характер спутного потока жидкости существенно зависит от расстояния между моделями. Показано, что увеличение расстояния между судами может приводить к значительному увеличению скорости спутного течения в раннем следе за счаленными корпусами, но при относительном продольном смещении судов такой картины не наблюдается. This work presents the results of the study of velocity fields that occur when a stream of fluid flows along “side by side” vessels’ mooring, depending on the hull forms, the distance between them and the relative displacement of the hull by laboratory, full-sized and numerical methods. Laboratory experiments were performed using an ADV-sensor. Field experiments were conducted with two tankers in the water area of ​​the river Volga. The FineMarineTM software package was used for numerical simulation. A correlation of the results of the flow velocity measurement by various methods showed sufficient convergence of the results. It was found that the cocurrent stream of fluid pattern for models of vessels with simplistic hull form depends heavily on the distance between the models. It is shown that an increase in the distance between the vessels can lead to a significant increase in the fluid velocity of the concurrent stream in the early wake of the hulls of vessels’ mooring, but this picture is not observed with a relative longitudinal displacement of the vessels.

Concentration of Impurities during Melting of Snow Made from Secondary Sewage Effluent

1986 ◽  
Vol 18 (2) ◽  
pp. 151-156 ◽  
Author(s):  
R. Zapf-Gilje ◽  
S. O. Russell ◽  
D. S. Mavinic
Keyword(s):  
Potassium Chloride ◽  
Chloride Solution ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Low Cost ◽  
Sewage Effluent ◽  
Potassium Chloride Solution ◽  
Laboratory Results ◽  
Solution Field ◽  
Concentration Of Impurities

When snow is made from sewage effluent, the impurities become concentrated in the early melt leaving the later runoff relatively pure. This could provide a low cost method of separating nutrients from secondary sewage effluent. Laboratory experiments showed that the degree of concentration was largely independent of the number of melt freeze cycles or initial concentration of impurity in the snow. The first 20% of melt removed with it 65% of the phosphorus and 90% of the nitrogen from snow made from sewage effluent; and over 90% of potassium chloride from snow made from potassium chloride solution. Field experiments with a salt solution confirmed the laboratory results.

scholarly journals Interactions Between Chill-Hours and Degree-Days Affect Carpogenic Germination in Monilinia vaccinii-corymbosi

2001 ◽  
Vol 91 (1) ◽  
pp. 77-83 ◽  
Author(s):  
H. Scherm ◽  
A. T. Savelle ◽  
P. L. Pusey
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Degree Days ◽  
Carpogenic Germination ◽  
Conditioning Period ◽  
Low Degree ◽  
Heating Degree Days ◽  
Relationship Of ◽  
High Degree ◽  
The Relationship

The relationship of cumulative chill-hours (hours with a mean temperature <7.2°C) and heating degree-days (base 7.2°C) to carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi, which causes mummy berry disease of blueberry, was investigated. In two laboratory experiments, pseudosclerotia collected from rabbiteye blueberry in Georgia were conditioned at 5 to 6°C for 26 to 1,378 h prior to placement in conditions favorable for germination and apothecium development. The number of chill-hours accumulated during the conditioning period affected the subsequent proportion of pseudosclerotia that germinated and produced apothecia, with the greatest incidence of carpogenic germination occurring after intermediate levels of chilling (≈700 chill-hours). The minimum chilling requirement for germination and apothecium production was considerably lower than that reported previously for pseudo-sclerotia from highbush blueberry in northern production regions. The rate of carpogenic germination was strongly affected by interactions between the accumulation of chill-hours and degree-days during the conditioning and germination periods; pseudosclerotia exposed to prolonged chilling periods, once transferred to suitable conditions, germinated and produced apothecia more rapidly (after fewer degree-days had accumulated) than those exposed to shorter chilling periods. Thus, pseudosclerotia of M. vaccinii-corymbosi are adapted to germinate carpogenically following cold winters (high chill-hours, low degree-days) as well as warm winters (low chill-hours, high degree-days). Results were validated in a combined field-laboratory experiment in which pseudosclerotia that had received various levels of natural chilling were allowed to germinate in controlled conditions in the laboratory, and in two field experiments in which pseudosclerotia were exposed to natural chilling and germination conditions. A simple model describing the timing of apothecium emergence in relation to cumulative chill-hours and degree-days was developed based on the experiments. The model should be useful for better timing of field scouting programs for apothecia to aid in management of primary infection by M. vaccinii-corymbosi.

scholarly journals Nitrogen management in wheat based on the normalized difference vegetation index (NDVI)

2018 ◽  
Vol 48 (9) ◽  
Author(s):  
André Luis Vian ◽  
Christian Bredemeier ◽  
Marcos Alexandre Turra ◽  
Cecília Paz da Silva Giordano ◽  
Elizandro Fochesatto ◽  
...  
Keyword(s):  
Technical Efficiency ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Field Experiments ◽  
Shoot Biomass ◽  
Sensor Field ◽  
N Dose ◽  
Plant Emergence ◽  
The Moment ◽  
The Relationship

ABSTRACT: Biomass production and nitrogen (N) accumulated in wheat shoots may be used for quantifying optimal topdressing nitrogen doses. The objective of this study was to develop and validate models for estimating the amount of biomass and nitrogen accumulated in shoots and the N topdressing dose of maximum technical efficiency in wheat using the normalized difference vegetation index (NDVI) measured by an active optical canopy sensor. Field experiments were carried out in two years and treatments consisted of N doses applied at plant emergence and as topdressing. NDVI, shoot biomass and N accumulated in shoots at the growth stage of six fully expanded leaves and grain yield were evaluated, being determined the topdressing N dose of maximum technical efficiency (DMTE). The NDVI was positively correlated to shoot biomass and N content in shoots and models for the relationship between these variables were developed and validated. The DMTE was negatively correlated with the NDVI value evaluated at the moment of N topdressing application. Thus, NDVI evaluation by an active optical canopy sensor can be used for nitrogen fertilization in variable rate, allowing the adjustment of applied N doses in different areas within a field.

Geometrical Characteristics of Fishing Boats Series of ITU

2007 ◽  
Vol 44 (02) ◽  
pp. 125-137
Author(s):  
Muhsin Aydin ◽  
Aydin Salci
Keyword(s):  
Computer Program ◽  
The Body ◽  
Hull Form ◽  
The Third ◽  
Geometrical Characteristics ◽  
Fishing Boat ◽  
Technical University ◽  
Hull Forms

In the present paper, first 13 hull forms of fishing boats with different block coefficients were generated. Later, 26 hull forms of fishing boats with two different ratios of length to beam were generated by utilizing previous hull forms of fishing boats mentioned. In total, 39 fishing boats were generated. This series is called "Fishing Boats Series of ITU" (Istanbul Technical University). In this Series, the forms of the body stations and beams of the boats are the same for equal block coefficient and different lengths. The ratio of the beam of any station at any waterline to the beam of boat, Bz/B varies with respect to block coefficient, CB. These variations have been represented with the third-degree polynomials. Thus, a hull form of the fishing boat in the desired length and block coefficient can be obtained by using these polynomials. For this purpose, a computer program called "Turetme" was developed. Finally, by using this program, three hull forms of fishing boats were obtained and presented here.

Ship Hull Form Optimization Using Artificial Bee Colony Algorithm

2014 ◽  
Author(s):  
Fuxin Huang ◽  
Lijue Wang ◽  
Chi Yang
Keyword(s):  
Drag Reduction ◽  
Artificial Bee Colony ◽  
Interpolation Method ◽  
Ship Hull ◽  
Mathematical Functions ◽  
Hull Form ◽  
Abc Algorithm ◽  
Bee Colony ◽  
Hull Forms ◽  
Fast Flow

In this paper, artificial bee colony (ABC) algorithms are introduced to optimize ship hull forms for reduced drag. Two versions of ABC algorithm are used: one is the basic ABC algorithm, and the other is an improved artificial bee colony (IABC) algorithm. A recently developed fast flow solver based on the Neumann-Michell theory is used to evaluate the drag of the ship in the optimization process. The ship hull surface is represented by discrete triangular panels and modified using radial basis function interpolation method. The developed optimization algorithms are first validated by benchmark mathematical functions with different dimensions. They are then applied to the optimization of DTMB Model 5415 for reduced drag. Two optimal hull forms are obtained by the ABC and the IABC algorithms. A large drag reduction is obtained by both of the algorithms. The optimal hull form obtained by the IABC algorithm has larger drag reduction than that of the hull form from the ABC algorithm. The results show that two ABC algorithms can be used for optimizing ship hull forms and the IABC algorithm has better performance than the ABC algorithm for the tested case in ship hull form optimization.

Floating Substations for Commercial-Scale Floating Windfarms

2021 ◽  
Author(s):  
Justin Jones ◽  
Ian Childs
Keyword(s):  
Water Depth ◽  
Direct Current ◽  
Wind Farms ◽  
Pilot Projects ◽  
Hull Form ◽  
Hydrodynamic Analysis ◽  
Commercial Scale ◽  
Hull Forms ◽  
Ancillary Equipment ◽  
Structural Code

Abstract As floating wind farms move from pilot projects to commercial-scale installations they will move further offshore and into deeper water. There will be a requirement for offshore substations to deliver the electricity to shore, for which floating support structures will be the preferred solution. This paper describes the challenges and development of solutions for commercial-scale HVAC and HVDC floating offshore substations. Two different floating substation concepts have been developed. Layouts for the electrical and ancillary equipment were initially developed, to enable efficient packaging and structural efficiency for the topsides. By integrating the hull and topsides, the overall mass of the structure is minimised, benefitting stability and reducing hull size. Hydrodynamic analysis of the substructures was performed and structural code checks on the hull and topsides were carried out in Sesam. Mooring designs for each structure for 250m water depth have been developed and analysed in Orcaflex. It is likely that alternating current (HVAC) export to shore will be used for shorter transmission distances and direct current (HVDC) will be used for longer transmission distances. HVDC and HVAC floating substations will have quite different hull forms. The larger topsides footprint and greater mass of the HVDC conversion equipment make a conventional semi-submersible hull form efficient when allied to a stressed-skin topsides structure. The smaller footprint, lighter weight and differing requirements for protection from the elements of the HVAC topsides make this inefficient, so a deep draught semi-submersible with a hybrid topsides is the preferred solution. It is concluded that floating substations suitable for large, commercial-scale wind farms will be the chosen solution for anything other than shallow water or close to shore.

A Comparison of Several Strategies to Optimize a Ship’s Aft Body

2011 ◽  
Vol 27 (04) ◽  
pp. 202-211
Author(s):  
Auke van der Ploeg
Keyword(s):  
Viscous Flow ◽  
Scale Effects ◽  
Full Scale ◽  
Ship Hull ◽  
Hull Form ◽  
Wake Field ◽  
Hull Forms ◽  
Definition Of

This paper describes a procedure to optimize ship hull forms, based on double body viscous flow computations with PARNASSOS. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. One of the object functions is an estimate of the required power. In this paper we will focus on how to improve this estimate, by using the B-series of propellers. Results of systematic variations applied to the VIRTUE tanker together with scale effects in the computed trends will be discussed. In addition, we will demonstrate how the techniques discussed in this paper can be used to design a model that has a wake field that strongly resembles the wake of a given containership ship at full scale.

scholarly journals A Novel Water-Shore-Line Detection Method for USV Autonomous Navigation

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1682 ◽  
Author(s):  
Xiong Zou ◽  
Changshi Xiao ◽  
Wenqiang Zhan ◽  
Chunhui Zhou ◽  
Supu Xiu ◽  
...  
Keyword(s):  
Line Segment ◽  
Autonomous Navigation ◽  
Field Experiments ◽  
Lower Boundary ◽  
Water Area ◽  
Epipolar Constraint ◽  
Shore Line ◽  
Inland River ◽  
Straight Line ◽  
Selection Of

For the navigation of an unmanned surface vehicle (USV), detection and recognition of the water-shore-line (WSL) is an important part of its intellectualization. Current research on this issue mainly focuses on the straight WSL obtained by straight line fitting. However, the WSL in the image acquired by boat-borne vision is not always in a straight line, especially in an inland river waterway. In this paper, a novel three-step approach for WSL detection is therefore proposed to solve this problem through the information of an image sequence. Firstly, the initial line segment pool is built by the line segment detector (LSD) algorithm. Then, the coarse-to-fine strategy is used to obtain the onshore line segment pool, including the rough selection of water area instability and the fine selection of the epipolar constraint between image frames, both of which are demonstrated in detail in the text. Finally, the complete shore area is generated by an onshore line segment pool of multi-frame images, and the lower boundary of the area is the desired WSL. In order to verify the accuracy and robustness of the proposed method, field experiments were carried out in the inland river scene. Compared with other detection algorithms based on image processing, the results demonstrate that this method is more adaptable, and can detect not only the straight WSL, but also the curved WSL.

scholarly journals Planning MAR Schemes Using Physical Models: Comparison of Laboratory and Field Experiments

2019 ◽  
Vol 9 (18) ◽  
pp. 3652
Author(s):  
Jana Sallwey ◽  
Felix Barquero ◽  
Thomas Fichtner ◽  
Catalin Stefan
Keyword(s):  
Vadose Zone ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Managed Aquifer Recharge ◽  
Physical Models ◽  
Aquifer Recharge ◽  
Operational Parameters ◽  
Flow Processes ◽  
Models Comparison ◽  
Other Regarding

Infiltration experiments in the context of managed aquifer recharge (MAR) are often conducted to assess the processes influencing the operation of full-scale MAR schemes. For this, physical models such as laboratory experiments and, less often, field experiments are used to determine process specifics or operational parameters. Due to several assumptions, scale-related limitations, and differing boundary conditions, the upscaling of results from the physical models is not straightforward. Investigations often lead to over- or underestimations of flow processes that constrain the translation of results to field-like conditions. To understand the restrictions and potential of different physical models for MAR assessment, surface infiltration experiments in different scales and dimensions, which maintained the same operational parameters, were conducted. The results from the different setups were compared against each other regarding the reproduction water flow in the vadose zone and the influence of parameters such as soil type and climate. Results show that mostly qualitative statements can be made, whereas quantitative analysis through laboratory experiments is limited.

Secondary fluid flows driven electromagnetically in a two-dimensional extended duct

2005 ◽  
Vol 461 (2058) ◽  
pp. 1659-1683 ◽  
Author(s):  
Zhi-Min Chen ◽  
W.G Price
Keyword(s):  
Steady State ◽  
Laboratory Experiments ◽  
Fluid Motion ◽  
Fluid Flows ◽  
Two Dimensional ◽  
Slip Boundary Conditions ◽  
Slip Boundary ◽  
Wave Numbers ◽  
Motion Problem ◽  
Secondary Fluid

This study focuses on two-dimensional fluid flows in a straight duct with free-slip boundary conditions applied on the channel walls y =0 and y =2 πN with N >1. In this extended wall-bounded fluid motion problem, secondary fluid flow patterns resulting from steady-state and Hopf bifurcations are examined and shown to be dependent on the choice of longitudinal wave numbers. Some secondary steady-state flows appear at specific wave numbers, whereas at other wave numbers, both secondary steady-state and self-oscillation flows coexist. These results, derived through analytical arguments and truncation series approximation, are confirmed by simple numerical experiments supporting the findings observed from laboratory experiments.

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