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Tytuł:
Fault identification in underwater vehicle thrusters via sliding mode observers
Autorzy:
Zuev, Alexander
Zhirabok, Alexey
Filaretov, Vladimir
Powiązania:
https://bibliotekanauki.pl/articles/1838162.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
underwater vehicle
thruster
fault identification
sliding mode observer
pojazd podwodny
identyfikacja uszkodzenia
sterowanie ślizgowe
Opis:
The paper is devoted to the problem of increasing the efficiency of underwater vehicles by using a fault diagnosis system for their thrusters which provides detection, isolation, and identification of minor faults. To address the problem, a two-stage method is proposed. At the first stage, a bank of diagnostic observers is designed to detect and isolate the emerging faults. Each observer in this bank is constructed to be sensitive to some set of faults and insensitive to others. At the second stage, additional observers working in sliding mode are synthesized in order to accurately estimate the error value in the signal obtained from the angular velocity sensor and to estimate deviations of the thruster parameters from their nominal values due to the faults. In contrast to the existing solutions, reduced-order (i.e., lower-dimensional) models of the original system are proposed as a basis to construct sliding mode observers. This approach permits reduction of the complexity of the obtained observers in comparison with the known methods, where full-order observers are constructed. The simulation results show the efficiency and high quality of all synthesized observers. In all cases considered, it was possible to detect typical faults, as well as estimate their values.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2020, 30, 4; 679-688
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Abundance and species composition of plankton in the Gulf of Gdańsk near the planned underwater outfall of the Gdańsk-Wschód (Gdańsk-East) sewage treatment plant
Autorzy:
Zmijewska, M.I.
Niemkiewicz, E.
Bielecka, L.
Powiązania:
https://bibliotekanauki.pl/articles/48867.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
biomass
abundance
plankton
underwater outfall
Baltic Sea
phytoplankton
Gdansk city
coastal area
treatment plant
zooplankton
Gdansk Gulf
Vistula River
distribution
Opis:
The aim of this paper is to determine the current biological state of life in the pelagic zone of the Gulf of Gdańsk in relation to the planned start-up of an underwater outfall which will discharge sewage from the Gdańsk–Wschód (Gdańsk–East) sewage treatment plant. The plankton material was collected during two research cruises in July and October 1998. The samples were taken at 15 stations in four profiles located near Wyspa Sobieszewska (Sobieszewo Island), perpendicular to the coastline. Both the taxonomic and numerical structure of phytoplankton and zooplankton were typical of the coastal area of the Gulf of Gdańsk. The species diversity depends on hydrological conditions, mainly input from the River Wisła (Vistula). The abundance and biomass of phytoplankton in 1998 were several times lower than in 1994 and 1995 in the area off Górki Wschodnie, the profile located closest to the planned construction site. This could have been caused by generally lower temperatures in 1998 in comparison to previous years. In the investigated area only traces of algal eutrophication indicator species were noted. However, potentially toxic species were confirmed and were most abundant near the Wisła mouth. The highest concentrations of pelagic fauna occur in the shallowest area closest to the shoreline. Long-term observations of the dynamics of the variations in abundance and species composition indicate the increasing significance of one particular species – Acartia bifilosa.
Źródło:
Oceanologia; 2000, 42, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method for the interpretation of sonar data recorded during autonomous underwater vehicle missions
Autorzy:
Zieja, Mariusz
Wawrzyński, Wojciech
Tomaszewska, Justyna
Sigiel, Norbert
Powiązania:
https://bibliotekanauki.pl/articles/32912850.pdf
Data publikacji:
2022
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
onar technologies
sea floor monitoring
autonomous underwater systems
Opis:
Image acquisition from autonomous underwater vehicles (AUVs) is useful for mapping objects on the seabed. However, there are few studies on the interpretation of data collected with side-scan sonar during autonomous underwater vehicle missions. By recording the seabed with 3D multibeam sonar, a large number of survey points can be obtained. The collected data are processed using applications based on remote sensing image processing. The data collected during AUV missions (or other sonar carriers) needs to be pre-processed to reach the proper effectiveness level. This process includes corrections of signal amplification (Time Varying Gain, or TVG) and geometric distortions of sonar images (Slant Range Corrections). It should be mentioned that, when carrying out the interpretation process for structures on the sea floor, sonar users need to understand the process of visualising seabed projections and depressions, as well as the resolution limitations of the sonar sensors.
Źródło:
Polish Maritime Research; 2022, 3; 176-186
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Verification of a numerical simulation code for underwater chain moor
Weryfikacja oprogramowania do symulacji podwodnego cumowania łańcuchowego
Autorzy:
Zhu, X.
Yoo, W.
Powiązania:
https://bibliotekanauki.pl/articles/139728.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
underwater chain mooring
verification of a numerical simulation accuracy
real experiment
numerical simulation code
podwodne cumowanie łańcuchowe
weryfikacja dokładności symulacji numerycznej
eksperyment w warunkach rzeczywistych
kod symulacji numerycznej
Opis:
Numerical simulation is an economical and effective method in the field of marine engineering. The dynamics of mooring cables has been analysed by a numerical simulation code that was created on a basis of a new element frame. This paper aims at verifying the accuracy of the numerical simulation code through comparisons with both the real experiments and a commercial simulation code. The real experiments are carried out with a catenary chain mooring in a water tank. The experimental results match the simulation results by the numerical simulation code well. Additionally, a virtual simulation of a large size chain mooring in ocean is carried out by both the numerical simulation code and a commercial simulation code. The simulation results by the numerical simulation code match those by the commercial simulation code well. Thus, the accuracy of the numerical simulation code for underwater chain mooring is verified by both the real experiments and commercial simulation code.
Symulacja numeryczna jest ekonomiczną i efektywną metodą w dziedzinie inżynierii okrętowej. Dynamikę lin cumowniczych analizowano numerycznie przy pomocy oprogramowania symulacyjnego stworzonego na podstawie nowego opisu elementu. Celem pracy była weryfikacja dokładności symulacji numerycznej przez porównanie z eksperymentami w warunkach rzeczywistych i z komercyjnym oprogramowaniem symulacyjnym. Eksperymenty prowadzono w cysternie z wodą, z użyciem cum łańcuchowych. Wyniki eksperymentów zgadzają się dobrze z wynikami symulacji numerycznej. Dodatkowo, wykonano wirtualną symulację cumowania oceanicznego na długiej cumie łańcuchowej stosując własny program symulacyjny i oprogramowanie komercyjne. Uzyskano dobrą zgodność wyników obydwu symulacji. Tak więc, dokładność opracowanego programu do symulacji podwodnego cumowania łańcuchowego została zweryfikowana zarówno na drodze doświadczalnej, jak i przez porównanie z oprogramowaniem komercyjnym.
Źródło:
Archive of Mechanical Engineering; 2016, LXIII, 2; 231-244
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geodiversity evaluation of the Słupsk Bank boulder area
Ocena georóżnordności głazowiska Ławicy Słupskiej
Autorzy:
Zalewska, I.
Najwer, A.
Zwoliński, Z.
Powiązania:
https://bibliotekanauki.pl/articles/111446.pdf
Data publikacji:
2018
Wydawca:
Instytut Morski w Gdańsku
Tematy:
geodiversity
seascapes
underwater landforms
Baltic Sea
georóżnorodność
krajobraz morski
podwodne formy terenu
Morze Bałtyckie
Opis:
The Słupsk Bank is a seascape area of high nature value, that consists of boulders related to glacial and post-glacial formation and a variety of underwater landforms, that form the habitat for numerous plants and animals. The aim of this paper was to evaluate geodiversity using geoinformation analysis consecutive steps, such as preparation of factor maps, map algebra etc. The resulting geodiversity map was based on a bathymetric relief energy map, a geomorphological map based on expert classification using the Bathymetric Position Index (BPI), and a lithological map showing average texture classes of sediments). Maps of geodiversity support the identification and delimitation of the geodiversity hotspots for nature protection, as well as the directions for management of valuable natural areas.
Ławica Słupska jest obszarem morskim o dużej wartości przyrodniczej, który składa się z głazów związanych z formacją lodowcową i polodowcową oraz różnorodnymi podwodnymi formami terenu, które stanowią siedlisko licznych roślin i zwierząt. Celem niniejszej pracy była ocena georóżnorodności za pomocą następujących po sobie etapów analizy geoinformacyjnej, takich jak przygotowanie map czynnikowych, algebry map itd. Wynikowa mapa georóżnorodność została oparta na batymetrycznej mapie energii rzeźby, mapie geomorfologicznej opartej na klasyfikacji eksperckiej z wykorzystaniem batymetrycznego indeksu pozycji (BPI) i litologicznej mapy pokazującej uśrednione klasy teksturalne osadów. Mapy georóżnorodności służą do identyfikacji i wytyczania obszarów o wysokiej georóżnorodności w celu ochrony przyrody, a także wspierają kierunki zarządzania cennymi obszarami przyrodniczymi.
Źródło:
Biuletyn Instytutu Morskiego w Gdańsku; 2018, 33, 1; 178-188
1230-7424
2450-5536
Pojawia się w:
Biuletyn Instytutu Morskiego w Gdańsku
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
O pewnej metodzie wspomagania identyfikacji wizyjnej obiektów podwodnych
On a method for supporting visual identification of underwater objects
Autorzy:
Żak, Bogdan
Garus, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/1359354.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
ozpoznanie akwenu podwodnego
przetwarzanie obrazów
identyfikacja obiektów na obrazach wizyjnych
reconnaissance of an underwater area
image processing
identification of objects in video images
Opis:
Poszukiwanie i wykrycie obiektów znajdujących się w toni wodnej realizowane jest przez grupy wyspecjalizowanych nurków i płetwonurków. Jednakże ich czas przebywania pod wodą oraz możliwości penetracji głębin są ograniczone. Z tych względów coraz częściej do tych zadań wykorzystywane są bezzałogowe pojazdy podwodne wyposażone w środki technicznej obserwacji do których należą między innymi kamery TV. Tak więc do rozpoznania i klasyfikacji obiektów podwodnych są wykorzystywane obrazy wizyjne pochodzące z kamer zainstalowanych na pojazdach. Proces rozpoznania i identyfikacji obiektów jest procesem żmudnym i trudnym, wymagającym analizy wielu sekwencji obrazów, dlatego dąży się do jego automatyzacji. Wychodząc na przeciw tym potrzebom w artykule przedstawiono koncepcję identyfikacji podwodnych obiektów na podstawie obrazów wizyjnych akwenu podwodnego przesłanego z bezzałogowego pojazdu podwodnego na okręt bazę. Opisano metody przetwarzania wstępnego obrazów wizyjnych akwenu podwodnego oraz metodę poszukiwania wybranych obiektów na tych obrazach i ich identyfikację przy wykorzystaniu transformaty Hougha. Ponadto w pracy przedstawiono wyniki wstępnego przetwarzania oraz identyfikacji dokonanej na obrazach akwenu podwodnego oraz obrazie po operacji rozplotu.
The search and detection of objects under water is carried out by groups of specialised divers. However, their time underwater and their ability to penetrate the depths are limited. For these reasons, the use of unmanned underwater vehicles equipped with technical observation equipment, including TV cameras, is becoming increasingly popular for these tasks. Video images from cameras installed on vehicles are used to identify and classify underwater objects. The process of recognition and identification of objects is tedious and difficult and requires the analysis of numerous sequences of images, and so it is desirable to automate this process. In response to these needs, this article presents the concept of identification of underwater objects based on visual images from an underwater body of water sent from an unmanned underwater vehicle to a base vessel. The methods of initial processing of the observed images from an underwater area as well as the method of searching for selected objects in these images and their identification with the use of the Hough transform will be described. Furthermore, the paper presents the results of the preliminary processing and identification of the observed images following a deconvolution operation.
Źródło:
Polish Hyperbaric Research; 2019, 1(66); 25-34
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Controlling a team of unmanned underwater vehicles performing water region search tasks
Autorzy:
Zak, A.
Powiązania:
https://bibliotekanauki.pl/articles/258474.pdf
Data publikacji:
2013
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
unmanned underwater vehicles
multi-agent systems
control
multiplayer cooperative games
Opis:
The article discusses a problem of performing a mission and controlling a team of unmanned underwater vehicles which perform a task of water region search. The team of underwater vehicles has been modelled as a multi-agent system, which made it possible to use the mechanism of multi-agent systems for controlling the team of cooperating underwater vehicles, with each vehicle being treated as an individual agent. Solutions to cooperation problems in multi-agent systems were proposed, including the presentation of the system structure and the data exchange method. Issues relating to cooperation actions in the team of underwater vehicles were described and solved using the theory of games and the vector quality index. The process of negotiations between the vehicles was modelled as the multiplayer cooperative game, which secured successful realisation of the task performed by the team of vehicles with respect to time, which represents the economic aspect of the task. The optimal solution was selected based on the vector quality index, which provided opportunities for minimisation of costs having the form of energy used by the entire team, and maximisation of profits in the form of time needed for completing the water region search task. The proposed method for dividing the action space in the water region search tasks performed by the team of underwater vehicles consists in assigning to each of cooperating underwater vehicles a task the realisation of which contributes to the realisation of the globally defined task. Finally, the results of water region search tasks performed by a team of cooperating underwater vehicles are presented and discussed taking into account possible vehicle failures happening during task realisation.
Źródło:
Polish Maritime Research; 2013, 2; 82-89
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy controller for underwater remotely operated vehicle which is moving in conditions of environment disturbance occurrence
Autorzy:
Żak, A.
Powiązania:
https://bibliotekanauki.pl/articles/242025.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
control
fuzzy logic
underwater remotely operated vehicle
modelling of environment disturbance
Opis:
Oceans fill two-third surface of the Earth and they are house for majority alive organisms of our planet. However human possibilities of cognition of this environment are very limited. To defeat these limitations lots of scientists dealing with exploration of depths, concentrates on unmanned, remote-controlled underwater vehicle. From seventieth years happened the development of unmanned underwater vehicles which currently administering all characteristic attribute of robot, and have the possibility of shifting and manipulation, ability of technical surroundings' observation, and sometimes are making independent decision in typical situations. For control of all devices of robot responds the system of steering which holds supervision beginning from the propulsion and finishing on switching the video cameras and lighting. In robot's control system the functions of regulator in feedback the most often is realized by operator which is the onlooking working object on monitor installed in deck console. Nowadays more often automatic system of control is used, therefore in this paper such system will be proposed. The main aim of paper is to introduce the results of research concentrated on controlling remotely operated underwater vehicle during movement in conditions of environment disturbance occurrence. Firstly the mathematical model of example ROV is briefly discussed. Next the environment disturbance and its taking into account in mathematical models is shortly described. Next the proposed control system which is using technology of fuzzy logic is presented. At the end the example results of research on stabilizing movements' parameters of ROV during environment disturbance occurrence, using ROV simulator were presented. The paper is finished by summary which include conclusions derive from results of research.
Źródło:
Journal of KONES; 2011, 18, 2; 499-507
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model symulacyjny bezzałogowego robota podwodnego
Simulation model of an unmanned underwater robot
Autorzy:
Żak, A.
Powiązania:
https://bibliotekanauki.pl/articles/223412.pdf
Data publikacji:
2004
Wydawca:
Akademia Marynarki Wojennej. Wydział Dowodzenia i Operacji Morskich
Tematy:
robot podwodny
prądy wodne
model symulacyjny
underwater robot
water currents
simulation model
Opis:
W pracy przedstawiono koncepcję środowiska symulacyjnego dla ruchu robota podwodnego. Krótko zaprezentowano model matematyczny pojazdu, na podstawie którego utworzono model symulacyjny. Omówiono także metody uwzględnienia wpływu prądów podwodnych oraz zmian rozkładu masy w modelu matematycznym robota. Ponadto została przedstawiona struktura programu symulacyjnego oraz opis przyjętego sposobu tworzenia wirtualnego akwenu podwodnego. Na koniec przedstawiono przykładowe wyniki z pracy programu symulacyjnego dla ruchu robota podwodnego.
The paper presents a concept of simulation environment for movement of an underwater robot. It briefly shows the mathematical model of the vehicle which was used to develop a simulation model. It also discusses methods which take into account the effect of underwater currents as well as changes in mass distribution in the mathematical model of robot. In addition, it presents the structure of the simulation program and description of the way adopted to create a virtual underwater area. Finally, it gives examples of the results from the simulation program for underwater robot movement.
Źródło:
Zeszyty Naukowe Akademii Marynarki Wojennej; 2004, R. 45 nr 3 (158), 3 (158); 135-150
0860-889X
Pojawia się w:
Zeszyty Naukowe Akademii Marynarki Wojennej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability Testing Method for Underwater ROVs
Metoda badania stateczności pojazdów głębinowych typu ROV
Autorzy:
Zając, Patryk
Dawidziuk, Marek
Olejnik, Adam
Powiązania:
https://bibliotekanauki.pl/articles/32697256.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
mechanical engineering
underwater technology
unmanned underwater vehicle
inżynieria mechaniczna
technologia prac podwodnych
bezzałogowy pojazd głębinowy
Opis:
The article presents the results of research carried out in the framework of an engineering thesis prepared at the Department of Underwater WorksTechnology of the Naval Academy in Gdynia. The objective of the work was to develop a method and a station to test the stability of deep-sea ROVs. Thestudy presents the theoretical basis of the method as well as the results of performed experiments.
W artykule przedstawiono wyniki badań wykonanych w ramach pracy dyplomowej inżynierskiej realizowanej w Katedrze Technologii Prac Podwodnych Akademii Marynarki Wojennej w Gdyni. Celem pracy było opracowanie metody i stanowiska do badania stateczności pojazdów głębinowych typu ROV. W materiale przedstawiono podstawy teoretyczne metody oraz wyniki wykonanych eksperymentów.
Źródło:
Polish Hyperbaric Research; 2021, 1(74); 23-34
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of Geopolymer Concrete for Underwater Concreting Properties
Autorzy:
Zaidi, Fakhryna Hannanee Ahmad
Ahmad, Romisuhani
Al Bakri Abdullah, Mohd Mustafa
Wan Ibrahim, Wan Mastura
Aziz, Ikmal Hakem
Junaidi, Subaer
Luhar, Salmabanu
Powiązania:
https://bibliotekanauki.pl/articles/2106595.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
geopolymer
underwater concrete
fly ash
kaolin
Opis:
For ages, concrete has been used to construct underwater structures. Concrete laying underwater is a very complex procedure important to the success or failure of underwater projects. This paper elucidates the influence of alkali activator ratios on geopolymers for underwater concreting; focusing on the geopolymer concrete synthesized from fly ash and kaolin activated using sodium hydroxide and sodium silicate solutions. The geopolymer mixtures were designed to incorporate multiple alkali activator ratios to evaluate their effects on the resulting geopolymers’ properties. The fresh concrete was molded into 50 mm cubes in seawater using the tremie method and tested for its engineering properties at 7 and 28 days (curing). The control geopolymer and underwater geopolymers’ mechanical properties, such as compressive strength, water absorption density, and setting time were also determined. The differences between the control geopolymer and underwater geopolymer were determined using phase analysis and functional group analysis. The results show that the geopolymer samples were optimally strengthened at a 2.5 alkali activator ratio, and the mechanical properties of the control geopolymer exceeded that of the underwater geopolymer. However, the underwater geopolymer was determined to be suitable for use as underwater concreting material as it retains 70% strength of the control geopolymer.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 2; 677--684
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistical Optimization of Underwater Lower-Frequency Sound Insulation for Locally Resonant Sonic Material Using Genetic Algorithm
Autorzy:
Yuan, Bo
Chen, Yong
Tan, Bilian
Li, Bo
Powiązania:
https://bibliotekanauki.pl/articles/177461.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
underwater acoustic
sound insulation
local resonance
statistical optimization
global optimum
Opis:
The locally resonant sonic material (LRSM) is an artificial metamaterial that can block underwater sound. The low-frequency insulation performance of LRSM can be enhanced by coupling local resonance and Bragg scattering effects. However, such method is hard to be experimentally proven as the Best optimizing method. Hence, this paper proposes a statistical optimization method, which first finds a group of optimal solutions of an object function by utilizing genetic algorithm multiple times, and then analyzes the distribution of the fitness and the Euclidean distance of the obtained solutions, in order to verify whether the result is the global optimum. By using this method, we obtain the global optimal solution of the low-frequency insulation of LRSM. By varying parameters of the optimum, it can be found that the optimized insulation performance of the LRSM is contributed by the coupling of local resonance with Bragg scattering effect, as well as a distinct impedance mismatch between the matrix of LRSM and the surrounding water. This indicates coupling different effects with impedance mismatches is the Best method to enhance the low-frequency insulation performance of LRSM.
Źródło:
Archives of Acoustics; 2019, 44, 2; 365-374
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices
Autorzy:
Yuan, B.
Chen, Y.
Jiang, M.
Tang, S.
He, M.
Tu, M.
Powiązania:
https://bibliotekanauki.pl/articles/177103.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
locally resonant phononic crystals
effective speed of sound
coupling band gaps
underwater acoustic materials
Opis:
Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.
Źródło:
Archives of Acoustics; 2017, 42, 4; 725-733
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field Study on Underwater Noise Emitted by Small Tourist Boats. Comparison Between the Use of Electric and Combustion Motors
Autorzy:
Yori, Alfio
Powiązania:
https://bibliotekanauki.pl/articles/31339825.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
small boat underwater noise
anthropogenic underwater noise
electric motor boat
underwater noise produced by tourist boats
Opis:
Small boats, possessing outboard engines, are widely used in tourism and mammal watching within marine protected areas. Noise generated by this type of vessels has the capacity to negatively affect marine fauna, especially marine mammals, which use sound throughout all the phases of their lives. These tourism boats used in mammal watching may use different propulsion systems, such as gas, diesel or electric engines. To characterize underwater noise emitted by this type of vessels becomes relevant not only when assessing the acoustic impact produced by these different propulsion systems over the marine fauna living inside these protected marine areas, but also when determining which one produces the least impact. A comparative study of underwater noise emissions coming from small touristic boats was made in this study. Boats were similar in capacity and functions, although possessing different propulsion systems. Measurements were made on two boats with a 50 Hp internal combustion engine and one 5 Hp electric boat. These boats were selected to be studied because they have practically the same size, possess the same passenger-capacity and are used to make similar jobs and routes inside the protected area where they are operated. The electric boat showed a considerable decrease in underwater noise emissions, especially in low frequencies. This boat will produce a lower accumulated exposition of the fauna to the noise or will allow a closer approach to the observed species. Measurements were made between September 2018 and January 2020
Źródło:
Archives of Acoustics; 2023, 48, 3; 347-358
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of the Effective Underwater Speaker Sound Modulated by Audible Sound Frequency Range of Large Cetaceans for Avoidance with Ship Collision
Autorzy:
Yamada, H.
Kobayashi, N.
Nakashima, T.
Kato, H.
Powiązania:
https://bibliotekanauki.pl/articles/116934.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Cetaceans
Underwater Speaker (UWS)
Underwater Speaker Sound
Audible Sound Frequency Range
Hydrofoils
Hydroacoustics
Avoidance with Ship Collision
Large Cetaceans
Opis:
The underwater speaker (UWS) has been installed on high speed vessels; hydrofoils (HF) with low-noise during their cruises, to avoid sudden collisions with large cetaceans, while its performance has remained uncertain because of the problem in quality of the produced sound. Thus, we developed a sound source for the UWS by modulating the sound based on the audible range of major large cetaceans so as to increase its utilities. To investigate the audible sound frequency range of cetacean, we tried two procedures, (1) indirect-estimation from relationship between cetaceans audibility and vocalization, and (2) indirect-estimation from measurements on the cochlear basal membrane. We also synthesized the two new sound sources which we can potentially expect an avoidance with large cetaceans. Through several field experiments with deploy the new sounds we reached a tentative conclusion that the new sound was effective in terms of inducing the cetaceans' avoidance reaction and would be also expected to be applied to other low-noise vessels.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2015, 9, 2; 213-217
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł

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