Advance Speed-Hull-Pump-Jet Interactions in Small ASV

2020 ◽  
Author(s):  
Angelo Odetti ◽  
Marco Altosole ◽  
Marco Bibuli ◽  
Gabriele Bruzzone ◽  
Massimo Caccia ◽  
...  
Keyword(s):  
Shallow Water ◽  
Technological Development ◽  
Hydrodynamic Characteristics ◽  
Shallow Waters ◽  
Towing Tank ◽  
Remote Areas ◽  
Autonomous Surface Vehicle ◽  
Jet Interactions ◽  
Advance Speed

This paper is related to the technological development of an innovative small-size Autonomous Surface Vehicle designed to meet the requirement of accessing, monitoring and protecting the shallow waters peculiar of the Wetlands. The first prototype of a fully electric, modular, portable, lightweight, and highly-controllable Autonomous Surface Vehicle (ASV) for extremely shallow water and remote areas, namely SWAMP, was developed by CNR-INM and DITEN-Unige. This catamaran is equipped with four azimuth Pump-Jet Modular (PJM) actuators designed for small-size (1 to 1.5 m long) ASV. The main advantage of Pump-Jet thrusters is that they are flush with the hull, thus minimizing the risks of damages due to possible grounding. This system is used to increase the manoeuvrability in narrow spaces and to increase the spacial resolution by allowing the access also in extremely shallow waters with smaller risk of loosing manoeuvrability. The knowledge of the hydrodynamic characteristics of the thruster and of the vessel allows to partly or fully identifying the vessel for a better controllability. With this aim a series of tests have been conducted in the DITEN towing tank. In particular advance resistance on the SWAMP hull in deep and shallow water, bollard pull and self-propelling tests with the Pump-Jet Module working have been carried out. The results of the tests with the effects of advance speed on the PJM performance is reported in this paper together with the description of the modelling of the thruster itself.

An innovative ASV for the monitoring of anthropogenic pressure on Wetlands

2020 ◽  
Author(s):  
Angelo Odetti ◽  
Gabriele Bruzzone ◽  
Marco Bibuli ◽  
Roberta Ferretti ◽  
Enrica Zereik ◽  
...  
Keyword(s):  
Shallow Water ◽  
Intelligent Systems ◽  
Biological Diversity ◽  
Technological Development ◽  
Shallow Waters ◽  
Anthropogenic Pressure ◽  
Single Beam ◽  
Autonomous Surface Vehicle ◽  
Hull Structure ◽  
The Impact

<p>This paper describes the technological development of an innovative Autonomous Surface Vehicle designed to meet the requirement of accessing the extremely shallow waters peculiar of the Wetlands. Wetlands are those geographic areas where water meets the earth and cover between 5 and 8 % of the Earth's surface. Wetlands include mangrove zones, swamps, bogs and marshes, rivers and lakes, alluvial plains and flooded forests, shallow coasts and coral reefs. In recent years, their importance is becoming more and more recognized and various international conventions, directives and projects work on the protection of these fundamental ecosystems. Wetlands are considered among the world’s most productive environments for their biological diversity. Nevertheless the number, quality and spacial resolution of surveys in these peculiar environments is reduced due to the absence of suitable tools expressly addressed to work in these areas. This reduces the possibilities of monitoring and protecting the Wetlands. In this paper the first prototype of an innovative class of reliable modular re-configurable lightweight ASVs for extremely shallow water and remote areas applications is presented. SWAMP (Shallow Water Autonomous Multipurpose Platform) is a fully electric, modular, portable, lightweight, and highly-controllable Autonomous Surface Vehicle (ASV). It is a catamaran equipped with azimuth pump-jet actuators, and it is characterized by small draft soft-foam, unsinkable hull structure with high modularity and a flexible hardware/software architecture. The main advantage of pumpjet motors is that they are flush with the hull, thus minimizing the risks of damages due to possible grounding. This system is used to increase the manoeuvrability in narrow spaces and to increase the special resolution also in extremely shallow waters. The introduction of a soft hull structure is suitable for working in coastal areas and in riverine environment where impacts can affect the survival of the robot. The foam of the hulls is drilled in order to make SWAMP a completely modular catamaran that is able to host various types of tools, such as intelligent systems, samplers, and sensors, together with thrusters that are, in this way, protected by the foam. A preliminary study is shown related to the bathymetry carried on with a single beam sonar in a Ligurian river after a series of floods. Liguria is one of the European regions where extreme events related to anthropic changes have had the greatest number of negative effects. In this kind of areas the use of suitable robots can improve the assessment and monitoring the impact of anthropogenic pressure in wetland ecosystems.</p>

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

MODELING MOVING BOUNDARY IN SHALLOW WATER BY LBM

2013 ◽  
Vol 24 (01) ◽  
pp. 1250094 ◽  
Author(s):  
Y. PENG ◽  
J. G. ZHOU ◽  
J. M. ZHANG ◽  
R. BURROWS
Keyword(s):  
Shallow Water ◽  
Present Model ◽  
Moving Boundary ◽  
Lattice Boltzmann Model ◽  
Shallow Waters ◽  
Shallow Water Flows ◽  
Moving Body ◽  
Body Boundary ◽  
Multiple Relaxation Time ◽  
Boltzmann Model

A lattice Boltzmann model (LBM) for a moving body in shallow waters is developed. Three different schemes, FH's, Guo's and MMP's schemes, for a curved boundary condition at second-order accuracy are used in the study and compared in detail. The multiple-relaxation-time (MRT) is adopted for better stability. In order to deal with the moving body boundary, a certain momentum is added to reflect the interaction between the fluid and the solid; and a refill method for new wetted nodes moving out from solid nodes has been proposed. The described method is applied to simulate static and moving cylinders in shallow waters. The corresponding experiments are further performed for validation of the present model. It is found that all of the three schemes produce similar results that agree well with the experimental data for the static cylinder. However, for the moving boundary, MMP's scheme performs best. Overall, the proposed modeling approach is able to simulate both, static and moving cylinders in shallow water flows at acceptable accuracy.

Quantification of Bioerosion by Sphaerechinus Granularis on ‘Coralugène’ Concretions of the Western Mediterranean

1997 ◽  
Vol 77 (2) ◽  
pp. 565-568 ◽  
Author(s):  
Stephane Sartoretto ◽  
Patrice Francour
Keyword(s):  
Shallow Water ◽  
Small Diameter ◽  
Western Mediterranean ◽  
Biological Agent ◽  
High Abundance ◽  
Shallow Waters ◽  
Mean Diameter ◽  
The Mean ◽  
The Mediterranean

Sphaerechinus granularis (Echinodermata: Echinidea) is involved in the erosion of ‘coralligène’ concretions in the Mediterranean. In shallow water (10 m), a high abundance of this species (>20 ind 25 m−2) is associated with small diameter individuals (56·7 ±7·7 mm). In deep clean waters (>40 m), the abundance is lower (<1 ind 25 m−2) and the mean diameter is higher (86·0±9·3 mm). Daily erosion of Corallinaceae by this species is related to the urchin diameter (r=0.87). Local variations in urchin abundance and diameter influence the amount of CaCO3 eroded annually. In shallow waters, the eroded CaCO3 mass reaches 210 g m−2 y−1 vs 16 g m−2 y−1 in coralligène concretions in deep clean waters. Sphaerechinus granularis is an important biological agent which substantially erodes the Mediterranean coralligène concretions.

Effect of Shallow Water on a Mathematical Hull at High Subcritical and Supercritical Speeds

1986 ◽  
Vol 30 (02) ◽  
pp. 85-93
Author(s):  
A. Millward ◽  
M. G. Bevan
Keyword(s):  
Shallow Water ◽  
Wave Theory ◽  
Hull Form ◽  
Towing Tank ◽  
Resistance Peak ◽  
Good Agreement ◽  
Made In

Experiments have been made in a towing tank to measure the resistance of a mathematical hull form in deepwater and in shallow water at high subcritical and supercritical speeds. The data have been compared with calculations using linearized wave theory for the same hull shape. The results have shown fairly good agreement, with the greatest differences occurring near the subcritical resistance peak.

Multi Vessel Interaction in Shallow Water

2009 ◽  
Author(s):  
Hans Fabricius Hansen ◽  
Stefan Carstensen ◽  
Erik Damgaard Christensen ◽  
Jens Kirkegaard
Keyword(s):  
Shallow Water ◽  
Wave Model ◽  
Irregular Waves ◽  
Numerical Code ◽  
Scale Model ◽  
Hydrodynamic Characteristics ◽  
Mooring Line ◽  
Industry Standard ◽  
Physical Scale ◽  
The Time Domain

A numerical package for simulating vessel motions in the time domain, WAMSIM, is extended to handle multiple moving bodies interconnected through a nonlinear mooring system. WAMSIM relies on the industry standard program WAMIT to calculate the hydrodynamic characteristics and interaction of multiple bodies in the frequency domain. The numerical code is used to simulate the motions and mooring line and fender forces of two LNG tankers moored side-by-side in shallow water. One of the gas tankers is moored to the sea floor through a turret with chain catenaries. Realistic short-crested irregular waves obtained from a Boussinesq wave model are used to force the model. Motion spectra of the simulated motions are compared to measured motions from physical scale model tests. The model shows good agreement with measured motions and mooring line forces.

Life history of Mysis stenolepis Smith (Crustacea, Mysidacea)

1975 ◽  
Vol 53 (7) ◽  
pp. 942-952 ◽  
Author(s):  
T. Amaratunga ◽  
S. Corey
Keyword(s):  
Young Adults ◽  
Life History ◽  
New Brunswick ◽  
Shallow Water ◽  
Field Study ◽  
Sexual Maturity ◽  
Developmental Stages ◽  
Shallow Waters ◽  
Passamaquoddy Bay ◽  
History Of

A 17-month field study showed that Mysis stenolepis in Passamaquoddy Bay, New Brunswick lives for about 1 year. Young are released in shallow water early in spring and grow rapidly during the summer. In the fall, young adults migrate to deeper water where they reach sexual maturity. Transfer of sperm lakes place during winter in deeper regions of the Bay. soon after which the males die. Females survive and in spring migrate to shallow waters to release young after which they die. Females breed once and carry an average of 157 young per brood. Developmental stages of the postmarsupial young are described and discussed.

scholarly journals Recognition of “flowering” processes on the base of remote sensing data in shallow water ponds on the example of the Azov Sea

2020 ◽  
Vol 175 ◽  
pp. 12013 ◽  
Author(s):  
Marina Ganzhur ◽  
Nikita Dyachenko ◽  
Olga Smirnova ◽  
Anna Poluyan ◽  
Natalya Panasenko
Keyword(s):  
Remote Sensing ◽  
Shallow Water ◽  
Satellite Images ◽  
Remote Sensing Data ◽  
Shallow Waters ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
Sensing Data ◽  
Azov Sea

This work considers to the processes of «bloom» phytoplankton processes that cause hypoxic phenomena in shallow waters the example of the Sea of Azov. For the accumulation of information, multichannel satellite images of remote sensing are taken as a basis. In the process, the task of programmatically highlighting the contours of the areas of «bloom» is implemented.

Innovative Ice Protection for Shallow Water Drilling: Part I — Presentation of the Concept

2006 ◽  
Author(s):  
Arne Gu¨rtner ◽  
Ove Tobias Gudmestad ◽  
Alf To̸rum ◽  
Sveinung Lo̸set
Keyword(s):  
Shallow Water ◽  
Shallow Waters ◽  
Drilling Rig ◽  
Modular Concept ◽  
Drilling Operations ◽  
Drifting Ice ◽  
Ice Impacts ◽  
Jack Up ◽  
Near Future ◽  
Ice Period

Recent discoveries of hydrocarbons in the shallow waters of the Northern Caspian Sea arise the need for intensive drilling activities to be carried out in the near future in order to explore the potentials. Experience with mobile drilling units in the seasonally ice infested waters solely originates from the current drilling campaign of the Sunkar drilling barge at Kashagan and Kalamkas. However, with increased drilling activities upcoming, innovative drilling concepts are desirable due to the objective of maintaining drilling operations during the ice period with conventional non-ice-resistant drilling platforms. Hence, this paper suggests the employment of external Shoulder Ice Barriers (SIBs) to protect a conventional jack-up drilling rig from the hazards of drifting ice in shallow water. The SIB’s design is suggested to increase the ice rubble generation at the ice facing slope and thereby provide sufficient protection from drifting ice impacts. The modular concept of the SIB makes it possible to deploy each module in a floating mode to site, whereupon they are ballasted and connected to each other, forming a sheltered position for the jack-up. Subsequent to the termination of the drilling campaign the SIB modules may be retrieved by de-ballasting and tow out, without having significant impact on the environment. This paper presents, on a technical feasible level, the concept of ice protection in shallow water by means of SIBs.

scholarly journals COMPARAÇÃO DA EFICIÊNCIA DE FORRAGEIO DAS GARÇAS EGRETTA CAERULEA E EGRETTA THULA NO ESTUÁRIO DE PARANAGUÁ, PARANÁ, SUL DO BRASIL

2021 ◽  
Vol 25 (01) ◽  
pp. 59-68
Author(s):  
Danila Syriani Veluza ◽  
◽  
Juliana Rechetelo ◽  
Emygdio Leite de Araújo Monteiro-Filho ◽  
Luiz Augusto Macedo Mestre ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Shallow Water ◽  
Capture Efficiency ◽  
Foraging Efficiency ◽  
Shallow Waters ◽  
Success Rates ◽  
Local Conditions ◽  
Foraging Site ◽  
Egretta Thula

The foraging efficiency of birds may vary according to local conditions as a result of the balance between energy consumption and expenditure. The foraging efficiency of Egretta thula (adults n=11) and Egretta caerulea (adults n=69 and juveniles n= 17) was compared in Paranaguá city estuary, in Paraná, Brazil. In 14 hours of observation divided into 2 minutes sessions per individual, were recorded foraging site (mud or shallow water), number of steps, total peckings and successful peckings, and were calculated the success rates, energy effort and capture efficiency. In shallow water E.thula was more efficient than E. caerulea. There was no intraspecific differences in E. thula regarding environments. Adults of E. caerulea were more efficient than juveniles, with greater efficiency in mud than in shallow waters environments. Differences in foraging efficiency between species may be related to the type of foraging according to feeding location.

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