1,929 results on '"Current meter"'
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2. Application of the Entropy Model to Estimate Flow Discharge and Bed Load Transport with Limited Field Measurements.
- Author
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Bahmanpouri, Farhad, Yadav, Anshul, Massari, Christian, De Santis, Domenico, Sharma, Ashutosh, Agarwal, Ankit, Sen, Sumit, Fraccarollo, Luigi, Moramarco, Tommaso, and Barbetta, Silvia
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SEDIMENT transport ,BED load ,FRICTION velocity ,DEVELOPING countries ,STREAMFLOW - Abstract
Sediment transport can be observed within the flow of water in rivers, canals, and coastal regions, encompassing both suspended-load transport and bed-load transport. Bed-load transport specifically occurs near the riverbed, playing a crucial role in the formation of the riverbed itself. The current study aimed to explore the process of sediment transport by employing the entropy concept as a theoretical approach. To this end, field data collected using a current meter in the Alaknanda River at Srinagar in India were utilized. A comparison was made between the calculated mean velocity and discharge values and the observed data obtained from the Central Water Commission (CWC), demonstrating a maximum error percentage of 9%. Subsequently, shear velocity was determined for various cross-sections under different flow scenarios. The Shields parameter was then derived from the shear-velocity distribution to evaluate the transport potential of the sediment particles. The model results showed varying bed-load transport rates that increased as the particle size decreased and the discharge rate increased. In conclusion, the study findings highlight the efficacy of utilizing the entropy theory for estimating flow discharge and sediment transport in developing countries. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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3. Wind and mini-hydraulic energy potential in the lower basins of the rivers of the mountain ranges, given their topology
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José Luis Salas Gonzales, Alembert Delfin Hilario Huaccha, Kent Rodrigo Mamani Hilasaca, Walid Andy Kana Hancco, David Tunti Alanocca, Duval Bremell Cruz Mamani, Jordán Sebastián Llave Halanoca, and Willy Roberto López Tejada more...
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Topology ,Bathymetry ,Anemometer ,Current meter ,Wind rose ,WRPLOT View Freeware 8.0.2 ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
This document intends to auscultate the potential wind and mini-hydraulic energy in the lower basins of the rivers of the mountain ranges; given its topology, taking as an example the lower basin of the Ocoña river in Arequipa Peru, characterized by the canyoning of the mountain range, from the coast (0 masl) to the highlands (4,500 masl), and by the important flow hydraulic when descending from the highlands to the Pacific Ocean, in an area of 16,045 km2. For this, the wind speed has been recorded in anemometers placed at 6, 12, and 18 m above the surface. The section of the river and its speed have also been determined, the height of the river's water level has been recorded; all with an hourly periodicity. With this information we have determined the potential for wind and mini-hydro energy in this characteristic place. Wind speeds in the order of 10 m/s have been obtained, with a persistence of 8 h a day. As for the mini-hydraulic, with a minimum flow of 50 m3/s there is a persistence greater than 90 %. In conclusion, the potential of wind, mini-hydro, and combined energy of the place is sufficient to satisfy various energy demands, from very small to very large. more...
- Published
- 2024
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4. Analisis Pengukuran Kecepatan Aliran Permukaan Sungai Dengan Metode “Large Scale Particle Image Velocimetry” Menggunakan Fotogrametri Terestris, Studi Kasus : Sungai Mungkung, Kabupaten Sragen.
- Author
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Maladzi, Havi Sheehan, Bashit, Nurhadi, and Sasmito, Bandi
- Abstract
Copyright of Journal of Indonesian Civil & Environmental Engineering / Jurnal Teknik Sipil & Lingkungan is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...
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- 2024
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5. Current meter methodology for discharge measurement in circular pipe.
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Purece, Cristian and Panaitescu, Valeriu
- Subjects
INTERPOLATION ,WATER power ,COINCIDENCE ,VELOCITY ,MEASUREMENT - Abstract
One of the main methods used for determining the discharge of a high head hydropower plant equipped with a circular penstock is the current meter method. The article presents a simple, but safe way to increase the accuracy of discharge measurement by means of the current meter method based on a new methodology for location velocity measuring points in the measuring section of a circular conduit. The proposed methodology utilizes the interdependence between the admissible interpolation and the radial distribution of the measuring points for diminishing the coincidence error, adopting the interpolation law proposed by Winternitz for this goal, a law that is both simple and whose calculation error is low. At the same time, the new methodology envisages increasing the number of intervals the admissible interpolating function domain is divided into through the measuring point lay out in a circular measuring section along a spiral considering that the interpolation error is inversely proportional to this number of intervals. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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6. DEVELOPMENT OF STAGE-DISCHARGE RATING CURVE AND RATING TABLE OF PIYARO MINOR AND DILWARO MINOR
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Shoukat Ali Shah, Madeeha Kiran, Rabia Dars, Aleena Nazir, and Shaharyar Hassan Ashrafani
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rating curve ,discharge ,current meter ,piyaro minor ,dilwaro minor ,Geology ,QE1-996.5 - Abstract
Developing a gauge-discharge relationship in rivers, canals, and minor flow is vital for controlling floods, managing water resources, Spatio-temporal analysis, socio-economic development, and sustaining the ecosystem. Accurate and consistent data of irrigation networks are perilous to scheduling and managing for accurate application of irrigation water. Most of the hydrologic engineering activities like hydraulics structure, designs, flood monitoring, surplus water, reservoir, canal, and minor’s operation depend on flowing water derived from Rating Curve (RC). The effective management of irrigation water is necessary for crop water requirements and seepage losses estimation. In this context, the present study showed the actual field level work tested at two minors of the Ghotki feeder canal namely Pyaro minor and Dilwaro minor. The main object of the study is to develop gauge-discharge relation and development of RC and Rating Table (RT). The current meter was used for taking discharge measurements with the area velocity technique in both minors. Moreover, stage-discharge RC and RT were developed for different flows of water for both minors in Origin Software. From the calculated results, Power equations were developed for both minors for the actual requirement of crop water in the command area. The results of the study calculated in RT of Piyaro minor between 0.5-5ft stage gave discharge 0.053 cusecs to 90.616 cusecs. While the RT of Dilwaro minor showed the range between 0.5ft-4ft stage gave 26.575cusec to 168.888 cusecs. Hence, the present study suggested that for both minors, automatic gauging stations should be established for the actual demand of irrigation water in the command area and di-siltation should be done on both minors to make availability of water at the tail section. more...
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- 2021
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7. Seawater motion-induced electromagnetic noise reduction in marine magnetotelluric data using current meters
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Kai Chen, Qingxian Zhao, Ming Deng, Xianhu Luo, and Jianen Jing
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Marine magnetotelluric ,Adaptive correlation noise-canceling filter ,Seawater motion-induced electromagnetic noise ,Current meter ,Geography. Anthropology. Recreation ,Geodesy ,QB275-343 ,Geology ,QE1-996.5 - Abstract
Abstract Seawater motion-induced electromagnetic (EM) noise along the seafloor has a large impact on marine magnetotelluric (MT) data quality. Although the mechanical stability of ocean bottom electromagnetic receivers (OBEMs) has improved due to buoyancy optimization, completely eliminating EM noise generated by seafloor currents as a result of instrument rocking or induction from the Earth’s magnetic field is still not possible. The velocity of the current represents the quantification of seafloor conditions. To mitigate this problem, we installed a current meter on an OBEM to measure the synchronous current velocity along with the OBEM data logger. For the marine EM surveys, we conducted two surveys composed of 42 marine EM data acquisition sites in the South China Sea. We observed a strong correlation between induced EM noise and current velocity when the speed was greater than 2 cm/s. Furthermore, we developed an adaptive correlation noise-canceling filter to reduce the induced EM noise, using the current meter data as a reference signal. The filter refined the coefficients using a least-mean-squares algorithm. We were able to reduce the induced EM noise by pre-filtering the raw time series data with an adaptive correlation noise-canceling filter and using current meter data from nearby sites. Since seafloor currents are clearly an issue that limits MT data quality, special efforts are necessary to reduce seawater motion-induced EM noise in marine MT surveys. more...
- Published
- 2020
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8. Electronic Sensors and Instruments for Coastal Ocean Observing
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Corredor, Jorge E. and Corredor, Jorge E.
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- 2018
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9. PENGEMBANGAN PROTOTIPE COUNTER CURRENT METER DENGAN PERHITUNGAN DEBIT SECARA SEMI OTOMATIS
- Author
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Isnan Fauzan Akrom and Adang S. Soewaeli
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counter ,current meter ,pengukuran debit ,otomatis ,Hydraulic engineering ,TC1-978 ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Salah satu alat yang digunakan dalam pengukuran debit di suatu saluran air atau sungai adalah dengan menggunakan Current Meter. Berdasarkan hasil pengukuran tersebut, debit aliran air dihitung menggunakan metode yang sudah ada. Mengingat muka air sungai dapat berubah sangat cepat terutama saat banjir, maka kepraktisan dan kecepatan pengukuran, serta penghitungan debit sangat diperlukan. Untuk menjawab tantangan tersebut diperlukan alat ukur Current Meter yang lebih praktis dan cepat dalam pengukuran dan perhitungan. Penelitian ini bertujuan untuk mengembangkan prototipe Counter Current Meter berbasis mikrokontroller yang dapat menyimpan data kecepatan air, menghitung data debit secara semi otomatis, dan dapat mengunduh data yang disimpan ke komputer. Hasil dari penelitian menunjukkan bahwa fungsi penghitung debit otomatis pada Counter hasil pengembangan dan perangkat lunak Counter pada komputer telah bekerja sesuai dengan perancangan. Perbedaan hasil perhitungan debit yang sangat kecil diantara perhitungan manual dengan perhitungan otomatis diduga disebabkan oleh perbedaan proses pembulatan yang mempengaruhi akurasi pada perhitungan. more...
- Published
- 2018
- Full Text
- View/download PDF
10. Seawater motion-induced electromagnetic noise reduction in marine magnetotelluric data using current meters.
- Author
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Chen, Kai, Zhao, Qingxian, Deng, Ming, Luo, Xianhu, and Jing, Jianen
- Subjects
- *
NOISE control , *ELECTROMAGNETIC noise , *GEOMAGNETISM , *UNDERWATER noise , *MAGNETOTELLURICS , *SEAWATER , *OCEAN bottom - Abstract
Seawater motion-induced electromagnetic (EM) noise along the seafloor has a large impact on marine magnetotelluric (MT) data quality. Although the mechanical stability of ocean bottom electromagnetic receivers (OBEMs) has improved due to buoyancy optimization, completely eliminating EM noise generated by seafloor currents as a result of instrument rocking or induction from the Earth's magnetic field is still not possible. The velocity of the current represents the quantification of seafloor conditions. To mitigate this problem, we installed a current meter on an OBEM to measure the synchronous current velocity along with the OBEM data logger. For the marine EM surveys, we conducted two surveys composed of 42 marine EM data acquisition sites in the South China Sea. We observed a strong correlation between induced EM noise and current velocity when the speed was greater than 2 cm/s. Furthermore, we developed an adaptive correlation noise-canceling filter to reduce the induced EM noise, using the current meter data as a reference signal. The filter refined the coefficients using a least-mean-squares algorithm. We were able to reduce the induced EM noise by pre-filtering the raw time series data with an adaptive correlation noise-canceling filter and using current meter data from nearby sites. Since seafloor currents are clearly an issue that limits MT data quality, special efforts are necessary to reduce seawater motion-induced EM noise in marine MT surveys. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
- View/download PDF
11. Structure and Variability of the Antilles Current at 26.5°N.
- Author
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Meinen, Christopher S., Smith, Ryan H., Johns, Elizabeth M., Garcia, Rigoberto F., Garzoli, Silvia L., Johns, William E., Moat, Ben I., Rayner, Darren, and Frajka‐Williams, Eleanor
- Subjects
DOPPLER effect ,GULF Stream - Abstract
Observations from five different systems provide a robust picture of the structure and variability of the Antilles Current, an important contributor to the oceanic flux budget, at 26.5°N during 2005–2015. The analysis includes three direct measurement technologies (current meters, shipboard acoustic Doppler current profilers, and lowered acoustic Doppler current profilers) and two geostrophy‐based measurement technologies (conductivity‐temperature‐depth profilers and pressure‐equipped inverted echo sounders). The direct systems are shown to produce weaker, and less variable, Antilles Current transport estimates than the geostrophy‐based systems. The record‐length‐mean geostrophic estimate for the Antilles Current is 4.7 Sverdrups (Sv; 1 Sv = 106 m3/s), and the daily temporal standard deviation is 7.5 Sv. The variations of the Antilles Current transport exceed those of the entire basin‐wide meridional overturning circulation, illustrating the impact of this unusual current. Seasonal variability shows a maximum northward transport in August–September; however, the seasonal component of the variability is weak, and aliasing of higher frequencies is still a problem even with 10.5 years of data. The dominant time scales of variability in the spectra are at 70 and 180 days, and there is indication of westward propagation of Rossby Wave‐like features into the region at a speed of 9 cm/s. There is no significant correlation between the Antilles Current transport variations and those of the Florida Current at 27°N, in phase or at lags/leads of up to 5 years, likely reflecting the varying coastal wave/wall jet time scales for information to pass from the basin interior through the Bahamas Islands. Plain Language Summary: The Antilles Current carries waters northward and northwestward around the Bahamas Islands. While scientists have known that the Antilles Current existed for decades, it has not been studied nearly as much as the stronger Florida Current to the west, even though studies have suggested that the Antilles Current plays a significant role in the north‐south exchange of heat and salt within the North Atlantic. This study uses five different types of measurement systems to quantify how much water is being carried by the Antilles Current every day, how variable that flow is over a 10.5‐year time period, and what typical salinity, temperature, and dissolved oxygen contents are for the waters carried by the flow. The study finds that on average, this current is carrying 4.7 ×106 m3 of water per second northward and that this flow can vary by more than 100% from day to day (i.e., some days the flow can actually reverse and go southward). The study reveals the time scales on which the current tends to vary, and it also provides some tantalizing evidence that the physics of the current may not be as simple as has been previously thought. Key Points: The Antilles Current carries 4.7 Sv northward at 26.5°N in the time mean during 2005‐2015, with a daily standard deviation of 7.5 SvThe dominant time scales of variability for the flow are near 70 and 180 days, with little indication of a meaningful seasonal cycleGeostrophic and direct velocity estimates within the Antilles Current core differ, with the direct estimates being noticeably weaker [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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12. Velocity Calibration of Doppler Current Profiler Transducers
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Marc Le Menn and Steffen Morvan
- Subjects
Doppler effect ,current meter ,profiler ,calibration ,velocity measurements ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Doppler current profilers are used in oceanography to measure oceanic circulation but also in hydrology to calculate the flow of rivers. They allow the retrieval of water mass profiles in terms of velocity and direction. Direction is obtained via an electronic compass and tilt sensors, while velocity is obtained by measuring Doppler pulse shifts back-scattered by particles located in water cells allocated along the instrument’s measurement range. Current meters are usually tested in towing basins or hydrodynamic channels, but these facilities present limits in terms of the measurement range, particles concentration and time costs. This paper presents a novel method developed to test the trueness of these velocity measurements in the laboratory, along with the uncertainty of this test and the results obtained with current meters and stand-alone profilers. The method is based on the measurement of the frequency of pulses emitted by each transducer of the instrument independently, and on the simulation of received echoes by a variable frequency sinusoidal signal. more...
- Published
- 2020
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13. Spatial interpolation of point velocities in stream cross-section
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Hasníková Eliška, Pavlásek Jiří, and Vach Marek
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open channel ,current meter ,cross-validation ,arithmetic mean ,inverse distance weighted ,thin-plate spline ,kriging ,Hydraulic engineering ,TC1-978 - Abstract
The most frequently used instrument for measuring velocity distribution in the cross-section of small rivers is the propeller-type current meter. Output of measuring using this instrument is point data of a tiny bulk. Spatial interpolation of measured data should produce a dense velocity profile, which is not available from the measuring itself. This paper describes the preparation of interpolation models. more...
- Published
- 2015
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14. Australian tidal currents – assessment of a barotropic model (COMPAS v1.3.0 rev6631) with an unstructured grid
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Mark Hemer, Mike Herzfeld, Darren Engwirda, and David Griffin
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geography ,QE1-996.5 ,Tidal range ,geography.geographical_feature_category ,Magnitude (mathematics) ,Geology ,Atmospheric sciences ,Current meter ,Amplitude ,Regional variation ,Barotropic fluid ,Tide gauge ,Sound (geography) - Abstract
While the variations of tidal range are large and fairly well known across Australia (less than 1 m near Perth but more than 14 m in King Sound), the properties of the tidal currents are not. We describe a new regional model of Australian tides and assess it against a validation dataset comprising tidal height and velocity constituents at 615 tide gauge sites and 95 current meter sites. The model is a barotropic implementation of COMPAS, an unstructured-grid primitive-equation model that is forced at the open boundaries by TPXO9v1. The mean absolute error (MAE) of the modelled M2 height amplitude is 8.8 cm, or 12 % of the 73 cm mean observed amplitude. The MAE of phase (10∘), however, is significant, so the M2 mean magnitude of vector error (MMVE, 18.2 cm) is significantly greater. The root sum square over the eight major constituents is 26 % of the observed amplitude. We conclude that while the model has skill at height in all regions, there is definitely room for improvement (especially at some specific locations). For the M2 major axis velocity amplitude, the MAE across the 95 current meter sites, where the observed amplitude ranges from 0.1 to 156 cm s−1, is 6.9 cm s−1, or 22 % of the 31.7 cm s−1 observed mean. This nationwide average result is encouraging, but it conceals a very large regional variation. Relative errors of the tidal current amplitudes on the narrow shelves of New South Wales (NSW) and Western Australia exceed 100 %, but tidal currents are weak and negligible there compared to non-tidal currents, so the tidal errors are of little practical significance. Looking nationwide, we show that the model has predictive value for much of the 79 % of Australia's shelf seas where tides are a major component of the total velocity variability. In descending order this includes the Bass Strait, the Kimberley to Arnhem Land, and southern Great Barrier Reef regions. There is limited observational evidence to confirm that the model is also valuable for currents in other regions across northern Australia. We plan to commence publishing “unofficial” tidal current predictions for chosen regions in the near future based on both our COMPAS model and the validation dataset we have assembled. more...
- Published
- 2021
15. Assessment the macrobenthic diversity and community structure in the Musi Estuary, South Sumatra, Indonesia
- Author
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Rozirwan, Fauziyah, Rezi Apri, Andi Agussalim, Melki, Iskhaq Iskandar, and Hartoni
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Hydrology ,geography ,geography.geographical_feature_category ,Community structure ,Estuary ,04 agricultural and veterinary sciences ,General Medicine ,010501 environmental sciences ,01 natural sciences ,Salinity ,Diversity index ,Current meter ,Abundance (ecology) ,Macrobenthos ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Water quality ,0105 earth and related environmental sciences - Abstract
The macrobentic community in the Musi Estuary is very diverse. However, it has been showing a declining trend recently due to an increase in waste from human activities entering the waters. This study aimed to assess the macrobenthic diversity and community structure and correlated to the water quality parameters of the Musi Estuary, South Sumatra. The method used was a survey collecting water quality parameters at eight observation stations. The salinity is measured with a refractometer, temperature is measured with a digital thermometer, pH is measured with a pH meter. The dissolved oxygen (DO), brightness and current are measured with a DO meter, Seichii disk, and current meter, respectively. The Ekman grab was used to collect the samples, and then we used a diversity index, a similarity index, and principal components analysis (PCA) for analysis. The results show that the water quality is found in a good condition for macrobenthos growths. The salinity is ranging between 0 and 15 ppt, temperature is about 29–30.8 °C, pH is about 7.6–8.1, the dissolved oxygen is found to be 3.2–12.5 mg/L, the brightness is about 4.71–31.67% and the current speed is about 0.02–0.08 m.s−1. The analysis also indicates that the microbenthic compositions consist of 18 species, which is grouped into five classes, namely Gastropods 56%, Crustacea 22%, Bivalve 11%, Actinopterygii 6%, and Polychaeta 5%, with an abundance of 0,67 to 13,33 Ind.m−2. The diversity index is generally in low categories (H′ more...
- Published
- 2021
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16. ANALISIS KARAKTERISTIK SUNGAI BANTIMURUNG KAB. MAROS
- Author
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Musa, Ratna
- Subjects
Kecepatan Aliran ,Debit Sungai ,Jenis Aliran ,Current Meter - Abstract
Darnawati - Sungai adalah aliran terbuka dengan ukuran geometrik sungai memiliki karakteristik dan bentuk yang berbeda antara satu dengan yang lainnya, hal ini disebabkan oleh banyak faktor diantarannya topografi, iklim, kemiringan lembah yang berubah seiring waktu, tergantung pada debit, material dasar dan tebing maupun segala gejala alam dalam proses pembentukannya. Tujuan dari penelitian ini adalah : mengetahui distribusi besar kecepatan aliran dari setiap cross section/potongan melintang di Sungai Bantimurung, 2. Mengetahui besarnya debit pada sungai untuk masing-masing cross section atau potongan melintang Sungai Bantimurung, 3. Mengetahui jenis aliran yang terjadi pada aliran dari pengaruh kecepatan aliran sungai. Pengolahan data dilakukan berdasarkan data kedalaman sungai, penampang melintang sungai, dan kecepatan aliran yang diperoleh dengan menggunakan alat current meter pada setiap bagian penampang melintang sungai. Hasil penelitian didapatkan bahwa besarnya kecepatan dan debit aliran untuk Sungai Bantimurung bagian hulu yaitu sebesar 0,215 m/dtk, dengan debit 0,506 m3/dtk; sungai bagian tengah 0,282 m/dtk dengan debit 0,737 m3/dtk; dan hilir 0,248 m/dtk dengan debit 1,254 m3/dtk dan nilai bilangan Froude yang terjadi pada aliran Sungai Bantimurung hulu sebesar Fr = 0,12 < 1, Sungai Bantimurung tengah sebesar Fr = 0,179 more...
- Published
- 2022
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17. Seasonal variation of the sound-scattering zooplankton vertical distribution in the oxygen-deficient waters of the NE Black Sea
- Author
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Vladimir A. Solovyev, Alexander G. Ostrovskii, Elena G. Arashkevich, and Dmitry A. Shvoev
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0106 biological sciences ,Biogeochemical cycle ,010504 meteorology & atmospheric sciences ,Backscatter ,010604 marine biology & hydrobiology ,Parasagitta setosa ,Sampling (statistics) ,Seasonality ,medicine.disease ,Mooring ,01 natural sciences ,Zooplankton ,Environmental sciences ,Current meter ,Oceanography ,medicine ,Geography. Anthropology. Recreation ,Environmental science ,GE1-350 ,0105 earth and related environmental sciences - Abstract
At the northeastern Black Sea research site, observations from 2010–2020 allowed us to study the dynamics and evolution of the vertical distribution of mesozooplankton in oxygen-deficient conditions via analysis of sound-scattering layers associated with dominant zooplankton aggregations. The data were obtained with profiler mooring and zooplankton net sampling. The profiler was equipped with an acoustic Doppler current meter, a conductivity–temperature–depth probe, and fast sensors for the concentration of dissolved oxygen [O2]. The acoustic instrument conducted ultrasound (2 MHz) backscatter measurements at three angles while being carried by the profiler through the oxic zone. For the lower part of the oxycline and the hypoxic zone, the normalized data of three acoustic beams (directional acoustic backscatter ratios, R) indicated sound-scattering mesozooplankton aggregations, which were defined by zooplankton taxonomic and quantitative characteristics based on stratified net sampling at the mooring site. The time series of ∼ 14 000 R profiles as a function of [O2] at depths where [O2] < 200 µm were analyzed to determine month-to-month variations of the sound-scattering layers. From spring to early autumn, there were two sound-scattering maxima corresponding to (1) daytime aggregations, mainly formed by diel-vertical-migrating copepods Calanus euxinus and Pseudocalanus elongatus and chaetognaths Parasagitta setosa, usually at [O2] = 15–100 µm, and (2) a persistent monospecific layer of the diapausing fifth copepodite stages of C. euxinus in the suboxic zone at 3 µm < [O2] < 10 µm. From late autumn to early winter, no persistent deep sound-scattering layer was observed. At the end of winter, the acoustic backscatter was basically uniform in the lower part of the oxycline and the hypoxic zone. The assessment of the seasonal variability of the sound-scattering mesozooplankton layers is important for understanding biogeochemical processes in oxygen-deficient waters. more...
- Published
- 2021
18. Ocean Current Velocity Measuring Device Based on Acoustic Time Difference Current Meter
- Author
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Zhao, Jichao, Dai, Fengzhi, Ma, Xin, and Wang, Fengkun
- Published
- 2020
- Full Text
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19. Current measurements of low-power battery driven devices
- Author
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Wahlberg, Marcus and Wahlberg, Marcus
- Abstract
A current meter has been designed, intended for surveillance of low-power battery driven devices with a large dynamic range in their current consumption. Among such devices may, for example, be nodes in a wireless sensor network (WSN). The large dynamic range originates in the nodes’ states from an active mode for data collection and communication to a sleep mode for preserving very limited energy and prolonging the lifetime of the device. The active mode draws current up to hundreds of milliamperes whilst the sleep mode’s current may be as low as 22 nA. This makes the dynamic range larger than 6 orders of magnitude. To perform measurements that prevail over noise sources and resolution of involved components, an increase in the SNR must be made. If the current is measured with a shunt resistor, this may be done by varying its resistance as required. The resistance should be as high as possible to maximize the SNR, but low enough such that the burden voltage of the current meter is kept within tolerances of the device. A literature study was done, and with the gained knowledge a circuit was designed and simulated in LTSpice. Then a printed circuit board (PCB) of the circuit was designed and implemented using Altium Designer (an ECAD program), manufactured and hand-soldered. The final PCB was tested but shown to have some design flaws that deteriorated the performance, for example too frequent switching of the current range. more...
- Published
- 2022
20. Discharge Measurement for a Part of Lesser Zab River by Using Georadar and Current Meter at Klesa of Erbil, NE Iraq
- Author
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Bapeer, Galawezh, Bakir, Hawkar B., Dawood, Anwer, Al-Ansari, Nadhir, Ghafur, Bahra D., Bapeer, Galawezh, Bakir, Hawkar B., Dawood, Anwer, Al-Ansari, Nadhir, and Ghafur, Bahra D.
- Abstract
A Ground Penetrating Radar for bathymetry and water current velocity was used to estimate the discharge value of Lesser Zab River at Klesa station with coordinates (35º 53’ 08.21′′ N, 44º 35′ 35.90′′ E). Two traverses were taken across the river which represented two sites in the Klesa area which were (A-B) traverse with the coordinates (N 3970652 and E 491898), and (C-D) traverse with the coordinates (N 3972195 and E 487681). Measuring water flow rate by velocity area method was done by Mid-section method, to confirm the validity of the data; two sections were conducted for each of the two traverses to deduce two radargrams along the profiles (A-B) and (D-C). The radargrams drew by using sophisticated software and were very helpful in detecting the river floor topography and depth variation along both profiles, the distance between the two sites was 5 km. The results indicate that the maximum width of the river at stations is 36.5m and the maximum water depth of Lesser Zab River is 4.75m, maximum velocity is 1.88 m/s. The water flow rate deviates from 136.737m3/s to 147.23m3/s. The average discharge for Lesser Zab river = 141.983 m3/s. This discharge is under normal average because the data was taken in November 2019. Because of the mild weather and the lack of electricity consumption, so using these results in water resource management and planning for satisfying domestic consumption, irrigation, industrial consumption, …etc. in the Klesa area, will be economically beneficial for the water management policy of the country, Validerad;2022;Nivå 1;2022-03-01 (sofila) more...
- Published
- 2022
- Full Text
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21. Novel Underwater Glider-Based Absolute Oceanic Current Observation Solutions
- Author
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Weimin Jiang, Dalei Song, Jinhui Fu, Xinning Wang, Zhaohui Chen, and Jin Wu
- Subjects
North pole ,Turbulence ,Underwater glider ,Computer science ,Acoustics ,010401 analytical chemistry ,Ocean current ,Sea trial ,Glider ,Interference (wave propagation) ,01 natural sciences ,0104 chemical sciences ,Current meter ,Inertial measurement unit ,Water environment ,Electrical and Electronic Engineering ,Instrumentation ,Velocity measurement - Abstract
This work indicates two novel ocean current observation methods that based on a glider type mobile platform. Glider with current meters are ideal current observation solutions for marine scientists since they have merits of large dynamic area and low power consumption, but their measurement accuracy is insufficient now. The proposed 1st solution, single point current meter compensated inversion method (SPCMCIM), is a revolution of the conventional inverse method by solving the acoustic Doppler to current profiler (AD2CP) induced turbulence problem. It’s a cooperated AD2CP and single point current meter (SPCM) algorithm that compensates the contaminated first AD2CP layer data. The physical position of the SPCM is also optimized according to a finite element analysis (FEA) study to minimize the interference generated by the SPCM. The 2nd method is solving the area restriction problems that AD2CP can just apply to non-pure water environment namely single point and inertial measurement inversion method (SPIMIM). It utilizes the SPCM as the only current observation source and takes advantages of physical properties of ocean currents. The currents are constitute of stable layers and each of them has a stable velocity, so the glider’s velocity variation can be obtained by reading the SPCM. The velocity variation in the transition process between layers can be acquired by the low cost inertial sensors. Finally, these theoretical studies were verified in an onsite sea trial. The SPCM and AD2CP was mounted to an underwater glider to measure the currents and a ship equipped AD2CP was used to provide the arbitrary data. Both of the proposed method can effectively measure the current velocity and induced significant enhancement than the classical inversion method. In particular, the first method conducted improvement of 70% accuracy by average. The 2nd one also shows an obvious improvement and has the advantage to deploy to high purity water area like deep lakes or north pole. more...
- Published
- 2021
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22. Satellite Altimetry and Current‐Meter Velocities in the Malvinas Current at 41°S: Comparisons and Modes of Variations.
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Ferrari, Ramiro, Artana, Camila, Saraceno, Martin, Piola, Alberto R., and Provost, Christine
- Abstract
Abstract: Three year long current‐meter arrays were deployed in the Malvinas Current at 41°S below a satellite altimeter track at about 10 years intervals. Surface geostrophic velocities (SGV) derived from satellite altimetric data are compared with the in situ velocities at the upper current meter (∼300 m). Multisatellite gridded SGV compare better with in situ observations than along‐track SGV. In spite of the proximity of the moorings to the complex Brazil‐Malvinas Confluence (BMC) region, satellite SGV are significantly correlated with the 20 day low‐passed in situ velocities (0.85 for along‐isobaths velocities, 0.8 for cross‐isobaths velocities). The recent in situ measurement period (2014–2015) stands out in the altimetry record with a long‐lasting (4 months) high level of eddy kinetic energy at the mooring site and a southernmost location of the Subantarctic Front (SAF). The first two modes of variations of sea level anomaly (SLA) over the BMC remarkably match the first two modes of the low‐passed in situ velocities. The first mode is associated with a latitudinal migration of the SAF, and the second with a longitudinal displacement of the Brazil Current overshoot. The two modes dominate the 24 year long record of SLA in the BMC, with energy peaks at the annual and semiannual periods for the first mode and at 3–5 months for the second mode. The SLA over the Southwest Atlantic was regressed onto the two confluence modes of SLA variations and showed remarkable standing wave train like structures in the Argentine Basin. [ABSTRACT FROM AUTHOR] more...
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- 2017
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23. Influence of Water Temperature on Results of Current Meter Calibration and Measurement
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Mattas Daniel and Ramešová Libuše
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current meter ,measurement uncertainty ,water temperature influence ,Hydraulic engineering ,TC1-978 - Abstract
On the basis of the results of calibration of current meters at water of varying temperatures, a hypothesis that water temperature influences measured water velocities was formulated. The analysis of our long-term data showed that the water temperature does have an influence on measured water velocity. This influence can be taken into account for practical purposes as a contribution to the uncertainty of measurements. The influence depends on the type of current meter propeller. This paper presents results obtained for the Ott C-2 current meter with propellers of the types 1, 2, 3, 5 and 6. Our analysis showed that the uncertainty is equal or less than 5% for measurements carried out in water with temperatures above 8°C. The differences between measured water velocities for water temperatures 5°C and 20°C reached maximum 6% (depending on the propeller) in a slowly flowing water (rotational frequency n = 1 s-1). For rotational velocity n ≥ 2 s-1 the differences between velocities measured at water temperatures 5 and 20°C were mostly under 3%. The less influenced propeller is of type 3 for which the uncertainty of measurement does not reach 5% even for water temperature 1°C if the rotational frequency is bigger than 0.7 s-1. more...
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- 2013
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24. A Method and Equipment for Continuously Testing the Permeability Coefficient of Rock and Soil Layers
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Rongchao Xu, Cui Datian, Chen Wei, and Meng Xu
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Article Subject ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Borehole ,02 engineering and technology ,Penetration (firestop) ,Permeability coefficient ,Engineering (General). Civil engineering (General) ,01 natural sciences ,020801 environmental engineering ,Volumetric flow rate ,Water level ,Current meter ,Soil horizon ,Geotechnical engineering ,TA1-2040 ,Geology ,0105 earth and related environmental sciences ,Civil and Structural Engineering ,Stratum - Abstract
The water pressure test and steady-flow pumping test are still commonly used for measuring the permeability coefficient of rock and soil strata. Limited by the fact that the average value of the permeability coefficient could be obtained only by this testing method, the accuracy of the experimental results of the permeability coefficient for special rock and soil strata is not good. Therefore, a new on-site testing method and equipment for continuously measuring the permeability coefficient of rock and soil strata is studied in this paper. The method is suitable for water pressure testing in borehole and the steady-flow pumping test. The technical proposal is when the pumping test or water pressure test is carried out, the final water penetration will tend to be a stable value, and then, the high-precision current meter probe will be placed at the bottom of the pumping test hole or water pressure test hole. For the pumping test, the current meter will be lifted uniformly from the bottom of the borehole testing section to the stable water level. Meanwhile, the flow rate of a differential zone of the tested section is continuously detected. For the water pressure test, the current meter will be lifted uniformly from the bottom of the borehole test section to the top of the borehole test section, and the flow rate of the differential section will be continuously detected. Through data analysis and processing, not only the average permeability coefficient of the detected sections can be obtained but also the permeability coefficient of the differential section of the rock and soil stratum can be calculated, respectively. Furthermore, the corresponding relationship between the permeability coefficient and the detected location can be obtained. In view of the abovementioned reasons, the leaking point, the specific position, and the leakage quantity of the detected section could be found out accurately, which will improve the accuracy of the testing results obviously. more...
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- 2020
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25. Convection under internal waves in an alpine lake
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van Haren, Hans, Dijkstra, Henk A., Sub Physical Oceanography, Marine and Atmospheric Research, Sub Physical Oceanography, and Marine and Atmospheric Research
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Convection ,0208 environmental biotechnology ,02 engineering and technology ,Atmospheric sciences ,01 natural sciences ,High-resolution moored temperature observations ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,Current meter ,Lake Garda ,Taverne ,0103 physical sciences ,Spectral slope ,Environmental Chemistry ,Internal waves ,Water Science and Technology ,Hydrogeology ,Turbulence ,Internal wave ,Mooring ,020801 environmental engineering ,Forced convection ,Deep-sea turbulence ,Geology - Abstract
Turbulent mixing processes in deep alpine Lake Garda (I) have not extensively been observed. Knowledge about drivers of turbulent fluxes are important for insights in the transport of matter, nutrients and pollutants, in the lake and in natural water bodies in general. In this paper, the occurrence of internal wave induced turbulent convection, termed 'internally forced convection', is addressed as opposed to the more common shear-induced turbulence in a density stratified environment. Observations are analyzed from a dedicated yearlong mooring holding 100 high-resolution temperature sensors at 1.5 m intervals under a single current meter in the deeper half of the 344 m deep lake-center. Episodically, the weakly density stratified waters in the lower 50 m above the lake-floor show spectral slope and coherence evidence of short-term (15–30 min) convective motions under internal waves that are supported by the stronger stratified waters above. The near-homogeneous conditions are not attributable to frictional Ekman dynamics, but to large-scale internal wave crests. more...
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- 2020
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26. Information support for the procedure of measuring the flow rate of water in open channels by a water current meter with Arduino Micro board
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Anastasiya Klimova, Dmytro Tagirovych Reut, and Serhii Klimov
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Data processing ,Microcontroller ,Current meter ,business.industry ,Arduino ,Electrical engineering ,Environmental science ,Metre ,Water current ,Information support ,business ,Volumetric flow rate - Abstract
The modernization of a typical water current meter is proposed to facilitate hydrological observations on natural and artificial open watercourses. An Arduino Pro Micro microcontroller board was used to read the speed of the current meter and primary data processing, programs were developed: for the lower level - a microcontroller located on the board, and for the upper level - a smartphone to determine the water speed. The programs take into account the peculiarities of converting data on the flow rate of water with a current meter and allow you to enter additional indicators that reduce the uncertainty of the results. more...
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- 2020
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27. Analytical and Numerical Study of Fluid Flow in Propeller-type Current-meters
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Mohammad Hossein Khozaei and Seyed Ahmad Nourbakhsh
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Current meter ,Mechanical Engineering ,Fluid dynamics ,Propeller ,Current (fluid) ,Industrial and Manufacturing Engineering ,Flow measurement ,Geology ,Marine engineering - Published
- 2020
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28. Development of Microcontroller Based Water Flow Measurement.
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Munir, Muhammad Miftahul, Surachman, Arif, Fathonah, Indra Wahyudin, Aziz Billah, Muhammad, Khairurrijal, Mahfudz, Hernawan, Rimawan, Ririn, and Lestari, Slamet
- Subjects
- *
MICROCONTROLLERS , *HYDRAULICS , *WATER currents , *PROGRAMMABLE read-only memory , *GEOTECHNICAL engineering - Abstract
A digital instrument for measuring water flow was developed using an AT89S52 microcontroller, DS1302 real time clock (RTC), and EEPROM for an external memory. The sensor used for probing the current was a propeller that will rotate if immersed in a water flow. After rotating one rotation, the sensor sends one pulse and the number of pulses are counted for a certain time of counting. The measurement data, i.e. the number of pulses per unit time, are converted into water flow velocity (m/s) through a mathematical formula. The microcontroller counts the pulse sent by the sensor and the number of counted pulses are stored into the EEPROM memory. The time interval for counting is provided by the RTC and can be set by the operator. The instrument was tested under various time intervals ranging from 10 to 40 seconds and several standard propellers owned by Experimental Station for Hydraulic Structure and Geotechnics (BHGK), Research Institute for Water Resources (Pusair). Using the same propellers and water flows, it was shown that water flow velocities obtained from the developed digital instrument and those found by the provided analog one are almost similar. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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29. Strömmätning för batteridrivna lågeffektenheter
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Wahlberg, Marcus
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current measurement ,auto-range ,current-range ,Inbäddad systemteknik ,Embedded Systems ,Current meter ,shunt resistor - Abstract
A current meter has been designed, intended for surveillance of low-power battery driven devices with a large dynamic range in their current consumption. Among such devices may, for example, be nodes in a wireless sensor network (WSN). The large dynamic range originates in the nodes’ states from an active mode for data collection and communication to a sleep mode for preserving very limited energy and prolonging the lifetime of the device. The active mode draws current up to hundreds of milliamperes whilst the sleep mode’s current may be as low as 22 nA. This makes the dynamic range larger than 6 orders of magnitude. To perform measurements that prevail over noise sources and resolution of involved components, an increase in the SNR must be made. If the current is measured with a shunt resistor, this may be done by varying its resistance as required. The resistance should be as high as possible to maximize the SNR, but low enough such that the burden voltage of the current meter is kept within tolerances of the device. A literature study was done, and with the gained knowledge a circuit was designed and simulated in LTSpice. Then a printed circuit board (PCB) of the circuit was designed and implemented using Altium Designer (an ECAD program), manufactured and hand-soldered. The final PCB was tested but shown to have some design flaws that deteriorated the performance, for example too frequent switching of the current range. more...
- Published
- 2022
30. Discharge measurements field validation using remote-controlled boat with ADCP
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Sperandelli, Daniel Iozzi, 1985, Gireli, Tiago Zenker, 1980, Francato, Alberto Luiz, Mauad, Frederico Fabio, Paula, Eduardo Coutinho de, Corrêa, Marcelo de Paula, Batista, Jose Anderson do Nascimento, Universidade Estadual de Campinas. Faculdade de Engenharia Civil, Arquitetura e Urbanismo, Programa de Pós-Graduação em Engenharia Civil, and UNIVERSIDADE ESTADUAL DE CAMPINAS more...
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Hidrometria ,Gaging station ,Estações fluviometricas ,Efeito Doppler ,Vazão, Medidores de ,Hydrometry ,Current meter ,Doppler effect ,Barcos ,Boats - Abstract
Orientador: Tiago Zenker Gireli Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo Resumo: A medição de vazões em rios é a base do monitoramento fluviométrico, indispensável para a gestão dos recursos hídricos cada vez mais demandados. O medidor acústico Doppler (ADCP) é o instrumento mais moderno para tal fim e, a partir da década de 2010 vem sendo utilizado sobre barcos telecomandados. O presente estudo visa preencher a lacuna existente na literatura sobre estudos de validação desta técnica recente. Entre 2015 e 2020, 112 medições foram realizadas em oito estações fluviométricas nas bacias hidrográficas dos Rios Tietê e Grande, estado de São Paulo. Resultados estatísticos indicaram que as medições em campo não diferiram dos valores de referência, validando o método de medição de vazão com ADCP e barco telecomandado. A nova técnica, por não necessitar de tripulação, permite a medição de cheias excepcionais sem trazer risco para a segurança dos hidrometristas, melhorando a precisão das curvas-chave no seu tramo superior em substituição às atuais técnicas indiretas de extrapolação, contribuindo para a melhor gestão dos recursos hídricos Abstract: Rivers discharge measurement is the basis of streamflow monitoring, essential for the management of water resources that are increasingly in demand. The acoustic Doppler current profiler (ADCP) is the most modern instrument for this purpose and, since the 2010s, it has been used on remote-controlled boats. Present study aims to fill the existing gap in the literature on validation studies of this recent technique. Between 2015 and 2020, 112 measurements were taken at eight gaging stations in the Tietê and Grande rivers basins, state of São Paulo. Statistical results indicated that field measurements did not differ from the reference values, validating streamflow measurement with ADCP and remote-controlled boat method. The new technique, as it does not require embarked personnel, allows the measurement of exceptional floods without posing a risk to the safety of hydrometrists, improving the accuracy of rating curves in its upper section, replacing prevailing indirect extrapolation techniques, contributing to better management of water resources Doutorado Recursos Hídricos, Energéticos e Ambientais Doutor em Engenharia Civil more...
- Published
- 2022
31. Discharge Measurement for a Part of Lesser Zab River by Using Georadar and Current Meter at Klesa of Erbil, NE Iraq
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Galawezh Bapeer, Hawkar B. Bakir, Anwer Dawood, Nadhir Al- Ansari, and Bahra D. Ghafur
- Subjects
Georadar equipment ,Geoteknik ,River bathymetry ,Geology ,Flow rate measurement ,Geotechnical Engineering ,Current meter ,Mid-section method - Abstract
A Ground Penetrating Radar for bathymetry and water current velocity was used to estimate the discharge value of Lesser Zab River at Klesa station with coordinates (35º 53’ 08.21′′ N, 44º 35′ 35.90′′ E). Two traverses were taken across the river which represented two sites in the Klesa area which were (A-B) traverse with the coordinates (N 3970652 and E 491898), and (C-D) traverse with the coordinates (N 3972195 and E 487681). Measuring water flow rate by velocity area method was done by Mid-section method, to confirm the validity of the data; two sections were conducted for each of the two traverses to deduce two radargrams along the profiles (A-B) and (D-C). The radargrams drew by using sophisticated software and were very helpful in detecting the river floor topography and depth variation along both profiles, the distance between the two sites was 5 km. The results indicate that the maximum width of the river at stations is 36.5m and the maximum water depth of Lesser Zab River is 4.75m, maximum velocity is 1.88 m/s. The water flow rate deviates from 136.737m3/s to 147.23m3/s. The average discharge for Lesser Zab river = 141.983 m3/s. This discharge is under normal average because the data was taken in November 2019. Because of the mild weather and the lack of electricity consumption, so using these results in water resource management and planning for satisfying domestic consumption, irrigation, industrial consumption, …etc. in the Klesa area, will be economically beneficial for the water management policy of the country Validerad;2022;Nivå 1;2022-03-01 (sofila) more...
- Published
- 2022
32. Slow build-up of turbidity currents triggered by a moderate earthquake in the Sea of Marmara
- Author
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Henry, Pierre, Sinan Özeren, M, Yakupoğlu, Nurettin, Çakir, Ziyadin, de Saint-Léger, Emmanuel, Desprez de Gésincourt, Olivier, Tengberg, Anders, Chevalier, Cristele, Papoutsellis, Christos, Postacioğlu, Nazmi, Dogan, Uğur, Karabulut, Hayrullah, Uçarkuş, Gülsen, Çağatay, Namik, Çağatay, M. Namik, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Istanbul Technical University (ITÜ), Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Yildiz Technical University (YTU), Kandilli Observatory and Earthquake Research Institute (KOERI), Boǧaziçi üniversitesi = Boğaziçi University [Istanbul], ANR-16-CE03-0010,MAREGAMI2016,Caractérisation de la lacune sismique dans la région d'Istanbul(2016), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), and Boğaziçi University [Istanbul] more...
- Subjects
Canyon ,geography ,Turbidity current ,geography.geographical_feature_category ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,Sediment ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Seafloor spreading ,Foreshock ,Current meter ,Complex response ,13. Climate action ,Sedimentary rock ,14. Life underwater ,Geology ,Seismology ,[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography - Abstract
Earthquake-induced submarine slope destabilization is known to cause debris flows and turbidity currents, but the hydrodynamic processes associated with these events remain poorly understood. Records are scarce and this notably limits our ability to interpret marine paleoseismological sedimentary records. An instrumented frame comprising a pressure recorder and a Doppler recording current meter deployed at the seafloor in the Sea of Marmara Central Basin recorded consequences of a MW = 5.8 earthquake occurring Sept 26, 2019 and of a Mw = 4.7 foreshock two days before. The smaller event caused sediment resuspension but no strong current. The larger event triggered a complex response involving a mud flow and turbidity currents with variable velocities and orientations, which may result from multiple slope failures. A long delay of 10 hours is observed between the earthquake and the passing of the strongest turbidity current. The distance travelled by the sediment particles during the event is estimated to several kilometres, which could account for a local deposit on a sediment fan at the outlet of a canyon, but not for the covering of the whole basin floor. We show that after a moderate earthquake, delayed turbidity current initiation may occur, possibly by ignition of a cloud of resuspended sediment. Some caution is thus required when tying seismoturbidites with earthquakes of historical importance. However, the horizontal extent of the deposits should remain indicative of the size of the earthquake. more...
- Published
- 2021
33. Evaluation of the effects of precipitation and flow characteristics on suspended sediment transport in mountain-type Mediterranean climate; Korkuteli Stream sample, Antalya, Turkey
- Author
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Tuncer Demir, Ahmet Serdar Aytaç, Ergin Canpolat, and Seçkin Çakmak
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Hydrology ,Sediment ,Rating curve ,STREAMS ,Seasonality ,medicine.disease ,Water level ,Current meter ,medicine ,General Earth and Planetary Sciences ,Environmental science ,Precipitation ,Sediment transport ,General Environmental Science - Abstract
Amount and type of suspended sediments in streams can change over seasonal timescales and during high-flow events. The dynamics of the suspended sediment in the streams and rivers of the Mediterranean region of Turkey are not yet fully understood, as studies are limited. In this study, it is aimed to analyze the seasonal variation of suspended sediment transported over 12 months in the Korkuteli Stream to reveal the relationship between precipitation, flow, and suspended sediment. The water level of the stream recorded automatically every 10 min using an Immersion Type Level Transmitter and the water velocity were measured with a Universal Current Meter. The flow rate was estimated with a rating curve produced from the water velocity and cross-sectional data. US-DH48 depth integration sampler was used to take the suspended sediment samples and these samples analyzed in the laboratory. A significant relationship was found between flow and suspended sediment (R2: 0.97). The amount of suspended sediment increased significantly during high flow periods. Although most of the precipitation occur in winter months, the amount and rate of suspended sediment increase significantly during the shorter flood period in summer months (e.g., May and June) due to short-term heavy precipitation. During the measurement period, the total amount of transported suspended sediment was calculated as 47246 tons, of which approximately 87% (41106 tons) was transported largely in June. more...
- Published
- 2021
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34. ON THE IMPROVEMENT OF THE TILTING BOTTOM CURRENT METER
- Author
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S. D. Obleukhov, A. O. Korzh, V. N. Nabatov, Maria Golenko, S. A. Shchuka, A. P. Podufalov, A. A. Kondrashov, and V. T. Paka
- Subjects
Physics ,Buoyancy ,Perforation (oil well) ,Reynolds number ,Mechanics ,engineering.material ,Physics::Fluid Dynamics ,Current meter ,Transverse plane ,symbols.namesake ,Tilt (optics) ,engineering ,symbols ,Cylinder ,Shroud - Abstract
The article describes the advanced design of Tilt Current Meter (TCM), developed in the Shirshov Institute of Oceanology. This type of meters is used in recent years mainly in Western countries due to low cost, ease of manufacture and the possibility of replication. In most designs the device is a physical pendulum in the form of a long floating cylinder attached to a stationary platform and deviating from the vertical in the action of hydrodynamic force. The tilt is recalculated to the flow rate by the accelerometer signals. The main drawback of the existing samples is the presence of contaminating signals in measurements due to transverse auto – oscillations of the cylinder in a stable flow in the formation of vortices wake. In the advanced design the watertight container with the electronics block and the additional element of buoyancy are placed in an external rigid shroud. The shroud is made of cylindrical plastic pipe with a wall perforation area of 55%, this measure effectively prevents the appearance of transverse oscillations in a wide range of Reynolds numbers. For the developed design the simple calculation ratios allowing to carry out estimation of a measuring range and sensitivity of the meter on the basis of its geometrical and mass parameters are given. The improved design of the ISTT is primarily intended for the measurement of weak bottom currents, although it is possible to regulate the sensitivity for measurements in the surf zone. The range of measured bottom current velocities is 3–56 cm/s with a maximum relative error of 25% for small velocities and 3–5% for maximum velocities. more...
- Published
- 2019
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35. PENGARUH VEGETASI TERHADAP TAHANAN ALIRAN PADA SALURAN IRIGASI
- Author
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Masimin Masimin, Eldina Fatimah, and I.E. Sulastri Sihotang
- Subjects
Hydrology ,Flow resistance ,Current meter ,Flow velocity ,Volume (thermodynamics) ,Flow (psychology) ,Environmental science ,Vegetation ,Flow depth ,Irrigation channel - Abstract
Irrigation channel in D.I. Timbang Deli, Deli Serdang district Sumut province has a total area of 520 Ha and a 5000 meter long secondary channel. Irrigation channel in D.I. Timbang Deli overgrown vegetation at the base and wall of the channel so it is expected to affect roughness. The objective of the study was the flow resistance with the variation of vegetation volume to the variation of the discharge. The method used in this study is field observation by measuring flow velocity, flow depth and vegetation volume (VT) on trapezoidal tract width of 3.75 m and height of 0.90 m along 154 m. Measurements were performed on 3 points of upstream, middle and downstream channels and 5 transverse dots X1 through X5 4 times with D1 debit variation of 1.32 m³/s and D2 of 0.98 m³/s. The dominant vegetation channels are rigid. Measurement velocity using current meter while for vegetation volume (VT) using grid method. The results showed that vegetation volume VT0 (0,00 m³/0,00%), VT1 (52,417 m³/21,14%), VT2 (70,7921 m³/24,51%) and VT3 (83,053 m³/30,42%). It is seen that the increase in vegetation volume can affect the flow resistance. The result of measurement increased the resistance of flow to VT0 0,052, VT1 equal to 0,062 with percentage 16,13%, VT2 equal to 0,108 with percentage 51,85% and VT3 equal to 0,122 with percentage 57,37% atD1. Meanwhile, at D2 there is an increase of flow resistance to VT0 by 0,044, VT1 is 0,052 with percentage 15,38%, VT2 equal to 0,058 with percentage 24,14% and VT3 equal to 0,070 with percentage 37,14%. This shows that the flow resistance VT0 is smaller than the flow resistance VT1, VT2 and VT3. From the above results are expected to conduct O and P channels by surrounding communities and related government. more...
- Published
- 2019
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- View/download PDF
36. Method for the Absolute Calibration of Direct-Current Current Transducers
- Author
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Yicheng Wang, Xiaoding Huang, Jianting Zhao, Changwei Zhai, Yunfeng Lu, and Qing He
- Subjects
Physics ,020208 electrical & electronic engineering ,Direct current ,02 engineering and technology ,Current source ,Current meter ,Transducer ,Current ratio ,Electromagnetic coil ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Calibration ,Electrical and Electronic Engineering ,Current (fluid) ,Instrumentation - Abstract
This paper describes an absolute method for calibrating commercial 1000:1 dc current transducers (DCCTs). By adding two auxiliary windings to produce 10:1 and 100:1 ratios, we use a three-step build-up method to establish the 1000:1 current ratio standard. First, we determine the 10:1 ratios of 11 DCCTs through permutation; second, we set up a two-stage composite DCCT to produce a 100:1 ratio; after switching auxiliary windings in the two-stage setup, we then derive the 1000:1 current ratio. The experimental results show that the requirements for the current source and the current meter are not stringent; their Type-B contributions to the overall uncertainties are very small. Type-A uncertainties which include factors such as the experimental environment and possible drifts of the output offsets of the DCCTs are experimentally determined. Repeated tests show that the current ratio standard has an expanded uncertainty of $0.26 \times 10^{-6}$ for the 1000:1 ratio. more...
- Published
- 2019
- Full Text
- View/download PDF
37. Proxies for heat fluxes to the Arctic Ocean through Fram Strait
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Jakub Marciniak, Pawel Schlichtholz, and Wieslaw Maslowski
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,010505 oceanography ,Flow (psychology) ,Sea-surface height ,Covariance ,Geotechnical Engineering and Engineering Geology ,Oceanography ,Mooring ,Atmospheric sciences ,01 natural sciences ,Current (stream) ,Current meter ,Heat flux ,Volume (thermodynamics) ,Computer Science (miscellaneous) ,Environmental science ,0105 earth and related environmental sciences - Abstract
Oceanic fluxes through Fram Strait may significantly contribute to climate variations in the Arctic. However, their observations are difficult. Here, a 26-year numerical model simulation is used to derive oceanic proxies for interannual variability in heat fluxes through Fram Strait. It is found that variability in the cross-slope gradient of sea surface height (SSH) across the West Spitsbergen Current (WSC) can explain about 90% of the variance of winter and annual mean volume transports of Atlantic water at 79°N. Given the strong covariance between the simulated heat flux in the slope current along Svalbard and the corresponding volume transport, variability of the SSH gradient across the WSC is also found to account for about 80% of the variance of heat flux associated with the northward flow through Fram Strait. Moreover, variations in the SSH gradient across the Arctic Slope Current (ASC) northeast of Svalbard at 31°E explain about 85% of the variance of heat flux there and about 80% of the variance of the net heat flux upstream through Fram Strait. Finally, about 85% and 75% of the variance of the net heat flux through Fram Strait is associated with anomalies of the eastward volume transport and depth-averaged core velocity in the ASC, respectively. These relations indicate that monitoring of the flow in the ASC, even with a single current meter mooring, or of the SSH gradient across this current derived from either in situ or remote measurements may provide useful proxies for the heat import to the Arctic Ocean. more...
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- 2019
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38. Characterizing surface circulation in the Taiwan Strait during NE monsoon from Geostationary Ocean Color Imager
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Dong-Ping Wang, Xianqiang He, Xuhua Cheng, Zifeng Hu, Yu-Huai Wang, Xiaohui Liu, Yiquan Qi, and Tao Wang
- Subjects
010504 meteorology & atmospheric sciences ,Severe weather ,0208 environmental biotechnology ,Ocean current ,Soil Science ,Geology ,02 engineering and technology ,Monsoon ,01 natural sciences ,Geostationary Ocean Color Imager ,020801 environmental engineering ,Current meter ,Ocean color ,Climatology ,Geostationary orbit ,Satellite ,Computers in Earth Sciences ,0105 earth and related environmental sciences ,Remote sensing - Abstract
The Taiwan Strait is the only channel connecting the South China Sea (SCS) and the East China Sea (ECS), and plays a key role in the material exchanges between SCS and ECS. The region however is poorly sampled during the northeast (NE) monsoon when severe weather hinders shipboard measurements. In this study, the surface circulations in the Taiwan Strait and the adjacent East China Sea are derived from the Geostationary Ocean Color Imager (GOCI) with a high spatiotemporal resolution. The satellite observations are limited by cloud over. Nevertheless, they provide the only surface flow observations useful in hypothesis testing. It is demonstrated that the transient surface currents can be classified into three regimes: a southwestward flow for strong winds, a northeastward flow for weak winds, and a cross-strait flow for moderate winds. The satellite observations are also valuable in validating model currents. Two high-resolution global ocean reanalysis products, the Hybrid Coordinate Ocean Model (HYCOM) and the Copernicus Marine Environment Monitoring Service (CMEMS), are examined. The reanalysis products are generally consistent with the satellite observations. The CMEMS moreover shows a superior performance. This study illustrates the unique capability of the geostationary ocean color satellite in providing spatially extensive surface flow observations in broad shelf regions where current meter data are sparse or non-existent. more...
- Published
- 2019
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39. Malvinas current at 44.7°S: First assessment of velocity temporal variability from in situ data
- Author
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Martin Saraceno, Ramiro Ferrari, Camila Artana, Guillermina Fernanda Paniagua, Marcela Charo, Alberto R. Piola, Christine Provost, Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos [Buenos Aires] (IFAECI), Centro de Investigaciones del Mar y la Atmósfera (CIMA), Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Centre National de la Recherche Scientifique (CNRS), Servicio de Hidrografia Naval, Servicio de Hydrografia Naval, Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Austral, Boréal et Carbone (ABC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Departamento de Ciencias de la Atmosfera y los Oceanos (DCAO), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU) more...
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Mesoscale meteorology ,IN SITU TIME SERIES ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,Escarpment ,Aquatic Science ,01 natural sciences ,Current meter ,Potential vorticity ,Bathymetry ,MALVINAS CURRENT VARIABILITY ,Sea level ,0105 earth and related environmental sciences ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,geography ,Plateau ,geography.geographical_feature_category ,010604 marine biology & hydrobiology ,ALTIMETRY DATA ,Geology ,PATAGONIAN SLOPE ,Geodesy ,Oceanography ,13. Climate action ,Ridge - Abstract
International audience; We report current meter measurements obtained by four moorings deployed across the Malvinas Current (MC) at 44.7ºS during 18 months between December 2015-June 2017. Previous measurements of the MC strength have been reported only close to the Brazil-Malvinas Confluence, hindering the interpretation of the flow variability. The record-length time averaged velocities and variance ellipses indicate a strong northward along-isobath flow with an equivalent-barotropic structure. The meridional velocities at the western and eastern moorings are not correlated and show large amplitude oscillations which are coherent with the passage of mesoscale features over the moorings. Satellite altimetry data, that are highly correlated with 20-day low-pass filtered in situ velocities (r~0.80), show that the MC variability is affected by the propagation of sea level anomalies (SLA) along the Patagonian slope with phase speeds that range between 0.21 ± 0.04 m s-1 and 0.14 ± 0.01 m s-1. SLAs propagate northward along the slope following contours of constant potential vorticity and its phase speeds decrease towards the east across the slope. SLAs that mostly affect the western mooring originate in the northern flank of the North Scotia Ridge while SLAs that mostly affect the eastern mooring originate along the Malvinas Escarpment, along the northern edge of the Malvinas Plateau. We suggest that the interaction between eddies and the complex bathymetry at those locations generate instabilities that enhance the generation of mesoscale structures that propagate in the flow direction along the western boundary of the Argentine Basin affecting the variability of the MC velocities. more...
- Published
- 2021
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40. Currents Generated by the Sea Breeze in the Southern Caspian Sea
- Author
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Rich Pawlowicz and Mina Masoud
- Subjects
Current (stream) ,Current meter ,Amplitude ,Water column ,Oceanography ,Continental margin ,Sea breeze ,Baroclinity ,General Medicine ,Forcing (mathematics) ,Geology - Abstract
The sea breeze system is the dominant atmospheric forcing at high frequency in the southern Caspian Sea. Here, we describe and interpret current meter observations on the continental margins of the southern Caspian from 2013 to 2014 to identify and characterize the water column's response to the sea breeze system. Time series analysis provides evidence for diurnal baroclinic current signals of O (0.02 m s−1) and surface height changes of O (0.03 m). A two-layer model, including interfacial and bottom friction is developed to further investigate the sea breeze response. This model is able to reproduce the structure, amplitudes, and phases of observed diurnal current fluctuations, explaining half of the variance in observational current response at frequencies at 1 cpd and higher. The sea breeze response thus results in a “tide-like” daily cycle which is actually linked to the local forcing all along the southern Caspian coast. more...
- Published
- 2021
- Full Text
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41. Measurement and calibration method of Doppler shift factor for underwater acoustic communication
- Author
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Hu Heming and Liu Yuan
- Subjects
Physics ,symbols.namesake ,Current meter ,Offset (computer science) ,Acoustics ,symbols ,Calibration ,Measurement uncertainty ,Metre ,Doppler effect ,Underwater acoustic communication ,Displacement (vector) - Abstract
Aiming at the estimation of Doppler shift factor in underwater acoustic communication, a new method based on current velocity measurement is proposed. By analyzing the relationship between current velocity and the Doppler shift factor, the calculation process of underwater acoustic communication system is simplified, the measurement method and ability of electromagnetic current meter is studied, and some on-site error sources are analyzed. The results indicate that the piecewise linear method can effectively characterize the measurement of electromagnetic current meter. Zero offset drift has to be modified frequently. The displacement effect is the main factor affecting the measurement results of the current meter, and the maximum indication error can be up to 10%. more...
- Published
- 2021
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- View/download PDF
42. On the discharge of bottom waters of the Northern Caspian into Derbent Depression through paleochannels.
- Author
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Ambrosimov, A.
- Subjects
OCEAN bottom ,WATER currents ,BUOYANCY ,GEOLOGICAL modeling ,GEOLOGICAL cross sections - Abstract
Data of seismoacoustic survey of a paleochannel, discovered on the northwestern slope of Derbent Depression, and the results of observations of currents on the bed of this channel were used to show that cold water of the Northern Caspian discharges into Derbent Depression via this paleochannel, thus avoiding the transit along the western coast of the Middle Caspian. Tentative estimates show the water discharge through the channel into the bottom zone of the sea to amouns to ∼12 km/year. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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43. Development of A Current Measuring Instrument for PEA Distribution Transformer using IoT Based
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Wuttiphong Pupatanan, Witsanu Promrat, Channarong Phongraktham, and Nateetorn Poonniam
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021103 operations research ,Computer science ,business.industry ,Transmitter ,0211 other engineering and technologies ,Electrical engineering ,02 engineering and technology ,Distribution transformer ,Signal ,Current meter ,Analog signal ,Metre ,Current (fluid) ,business ,Overhead line - Abstract
This paper presents the design of the current meter showing results through a smartphone application, to measure the current for PEA pole-mouth distribution transformer on the low-voltage side. This tool can reduce the danger that may occur to the staff in high locations, as well as reduce working time. Base on the principle of the current transmitter measured the current of the overhead line, convert to the current signal from 4-20 mA. The current signals transmitter to the analog signal, this signal detected by ESP8266 mini-WiFi. Then processed into actual values compare with the standard clamp meter. The device can indicate the current value via WiFi communication on a smartphone, the current value that is measured has an error no more than 2.74% compared to the standard clamp meter. more...
- Published
- 2021
- Full Text
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44. Evaluación de la fuente de incertidumbre en la curva de descarga de la microcuenca 'Las Flores', San Sebastián, Manabí, Ecuador
- Author
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Denisse Alexandra Marcillo Barahona, José Ramón Alarcón Loor, and Paul Adrián Vivas Alcívar
- Subjects
Current meter ,Mean squared error ,Simulated data ,Statistics ,Microsoft excel ,Mathematics - Abstract
El presente trabajo de investigación mixta indagó y comparó mediante una evaluación, la incertidumbre asociada a la curva de descarga simulada en la microcuenca Las Flores, en San Sebastián, Manabí, Ecuador, con la finalidad de disminuir los diferentes aspectos de incertidumbre que estaban en cuestionamiento, debido a la falta de datos reales para generar una curva de descarga. Se recopilaron datos mediante 12 aforos realizados por dos métodos diferentes (correntómetro y volumétrico). Se generó la comprobación de la relación entre los datos simulados y datos obtenidos, a través del cálculo de la raíz del error cuadrático medio (RECM), ejecutado mediante los programas Microsoft Excel y Hec-Ras, usados también para verificar los resultados. more...
- Published
- 2021
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45. Persistent, depth-intensified mixing during the Western Mediterranean Transition's initial stages
- Author
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R. Balbin, Alberto C. Naveira-Garabato, J. M. Fernández-Díaz, S. Piñeiro, Jordi Salat, R. Sánchez‐Leal, César González-Pola, Pere Puig, Agencia Estatal de Investigación (España), Ministerio de Economía y Competitividad (España), and Ministerio de Ciencia, Innovación y Universidades (España) more...
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Mediterranean climate ,Balearic islands ,Vertical diffusion ,Deep-ocean mixing ,Western Mediterranean Transition ,SeaDataNet ,government.political_district ,Oceanography ,Data availability ,Current meter ,Centro Oceanográfico de Baleares ,Geophysics ,Geography ,Space and Planetary Science ,Geochemistry and Petrology ,Deep water renewal ,Earth and Planetary Sciences (miscellaneous) ,government ,Medio Marino - Abstract
Piñeiro, S., González-Pola, C., Fernández-Díaz, J. M., Naveira-Garabato, A. C., Sánchez-Leal, R., Puig, P., et al. (2021). Persistent, depth-intensified mixing during the Western Mediterranean Transition's initial stages. Journal of Geophysical Research: Oceans, 126, e2020JC016535. https://doi.org/10.1029/2020JC016535. © 2020. American Geophysical Union. All Rights Reserved., © 2020. American Geophysical Union. All Rights Reserved. Major deep-convection activity in the northwestern Mediterranean during winter 2005 triggered the formation of a complex anomalous deep-water structure that substantially modified the properties of the Western Mediterranean deep layers. Since then, evolution of this thermohaline structure, the so-called Western Mediterranean Transition (WMT), has been traced through a regularly sampled hydrographic deep station located on the outer continental slope of Minorca Island. A rapid erosion of the WMT's near-bottom thermohaline signal was observed during 2005–2007. The plausible interpretation of this as local bottom-intensified mixing motivates this study. Here, the evolution of the WMT structure through 2005–2007 is reproduced by means of a one-dimensional diffusion model including double-diffusive mixing that allows vertical variation of the background mixing coefficient and includes a source term to represent the lateral advection of deep-water injections from the convection area. Using an optimization algorithm, a best guess for the depth-dependent background mixing coefficient is obtained for the study period. WMT evolution during its initial stages is satisfactorily reproduced using this simple conceptual model, indicating that strong depth-intensified mixing (K ∞ (z) ≈ 22 × 10−4 m2 s−1; z ⪆ 1,400 dbar) is a valid explanation for the observations. Extensive hydrographic and current observations gathered over the continental slope of Minorca during winter 2018, the first deep-convective winter intensively sampled in the region, provide evidence of topographically localized enhanced mixing concurrent with newly formed dense waters flowing along-slope toward the Algerian sub-basin. This transport-related boundary mixing mechanism is suggested to be a plausible source of the water-mass transformations observed during the initial stages of the WMT off Minorca., CTM2014-54374-R. BES-2015-074316., Estudio de la anomalía termohalina en las aguas profundas del Mediterráneo Occidental y su relación con las oscilaciones climáticas, ATHAPOC, SI more...
- Published
- 2021
46. Sensor fouling prevention in an acoustic current meter, MAVS.
- Author
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Williams, Albert J.
- Abstract
Coatings to inhibit attachment of marine organisms to sensors were applied to acoustic velocity sensors and tested for seven months in near-surface waters in Woods Hole, Massachusetts and found to effectively prevent attachment of fouling organisms to substrates of ABS plastic, epoxy, urethane, and to a lesser degree to stainless steel. This treatment was effective longer than biocides generally have been in these conditions. The material in the coatings, silicone in some form, prevents the organisms from getting a tight grip and they either do not manage to settle or are washed off by natural low-velocity currents and waves in the mooring field in Eel Pond harbor. [ABSTRACT FROM PUBLISHER] more...
- Published
- 2012
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47. Low-power circuit structures for chip-scale stimulating implants.
- Author
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Lehmann, Torsten, Jung, Louis, Moghe, Yashodhan, Chun, Hosung, Yang, Yuanyuan, and Alex, Asish Zac
- Abstract
Implantable electronic circuits are required to operate with low power dissipation due to the difficulties in supplying power transcutaneously and removing heat from the implant site without dangerous temperature elevation. In chip-scale implants, the circuit design is further restricted by the small implant volume and resulting requirement for a fully on-chip circuit implementation. In this paper we present low-power circuit structures for key functions in chip-scale stimulating implants: power transfer circuits, power supply circuits, communications circuits, stimulating circuits, and leakage monitoring circuits. [ABSTRACT FROM PUBLISHER] more...
- Published
- 2012
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48. Fish fauna of peatland waters in the middle Mahakam, Kutai Kartanegara, East Kalimantan, Indonesia
- Author
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Iwan Suyatna, Komsanah Sukarti, Tunggul Butarbutar, Henny Pagoray, Arif Data Kesuma, Muhammad Raafi, and Muhammad Bagja Britania Suyatna
- Subjects
Peat ,biology ,Fauna ,Fishing ,STREAMS ,biology.organism_classification ,Snakehead ,Fishery ,Environmental sciences ,Current meter ,Geography ,Bagridae ,Cyprinidae ,GE1-350 - Abstract
A field study was carried out to collect fish from the lake and streams/rivers around the peatland from December 2020 to February 2021. Fishing gears such as gillnet, snakehead pole and line, lift net, trap net ("sawaran", "julu"), and fish pot ("tokong", "pangilar", "bubu" or "lukah" and "tempirai") were operated. Sampling sites, water velocities, and water depth were measured using GPS Garmin 60 CSX, current meter hydrologic velocity meter, and fishfinder Portable, respectively. Generally, water velocities of streams measured were much more rapid than the lakes ranging between 0.33 m/s (at water depth: 4.20 m) and 0,69 m/s (at water depth: 6.80 m); and "not detected" (at water depth: 2.40 m) and 0.34 m/s (at water depth: 1.20 m) respectively. Of 7,377 fish samples, there were 50 species discovered belonging to 19 families. Cyprinidae was the most populated in individuals and species as well (1,022 Ind.; 21 taxa). It was followed by Bagridae (63 Ind.; five taxa), Channidae (53 Ind.; three taxa), Clariidae (10 Ind.; three taxa), Siluridae (403 Ind.; three taxa), while other families had just one taxon. Diversity was observed higher in streams (35 species) than lakes (30 species). Local fishers are still performing unselective fishing for feeding fish cage culture. more...
- Published
- 2021
49. Precision and accuracy of streamflow measurements in headwater streams during baseflow
- Author
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Camyla Innocente dos Santos, Pedro Luiz Borges Chaffe, Alondra Beatriz Alvarez Perez, Pedro Ferreira Arienti, and João Henrique Macedo Sá
- Subjects
Technology ,Accuracy and precision ,Hydrometry ,010504 meteorology & atmospheric sciences ,0207 environmental engineering ,02 engineering and technology ,STREAMS ,Aquatic Science ,Oceanography ,01 natural sciences ,Headwater streams ,River, lake, and water-supply engineering (General) ,Current meter ,Streamflow ,Geography. Anthropology. Recreation ,GE1-350 ,020701 environmental engineering ,Baseflow ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,TC401-506 ,Hydrology ,Hydraulic engineering ,Environmental sciences ,Dilution method ,Environmental science ,TC1-978 - Abstract
The quantification of baseflow is key for water resources management. However, there are few reports on the precision and accuracy in low streamflow measurements. In this paper, we systematically analyze the precision and accuracy of dilution streamflow measurements in headwater channels during baseflow. Precision refers to the variability of the values for repeated measurements and accuracy is how much the measured value approximates the reference one. We measured streamflow in 31 different cross-sections with contributing areas ranging from 0.02 to 5.33 km2. Streamflow measurements with the current meter were adopted as reference for accuracy estimation. A precision error of ±5.0% was found for the measurements. The percent errors compared to reference streamflow ranged from 0.7 to 45.6%, with a median of 6.1%. Precision and accuracy are in the same order of magnitude found in the literature for larger streams. These results can be used for constraining the uncertainty of streamflow measurements and rainfall-runoff modeling of headwater streams. more...
- Published
- 2021
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50. Detection and analysis of surface currents in western Guangdong by compact surface wave radar
- Author
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Junjie Li and zili Li
- Subjects
Mean squared error ,Ocean current ,law.invention ,Environmental sciences ,Current meter ,Bistatic radar ,Flow velocity ,Surface wave ,law ,GE1-350 ,Radar ,Energy (signal processing) ,Geology ,Remote sensing - Abstract
In order to study the detection performance of compact surface wave radar on ocean surface current in the west of Guangdong Province, firstly, the bistatic radar is set up to collect ocean echo data on the west coast of Guangdong Province. Then, by using the Multiple Signal Classification (MUSIC) algorithm, the comparative analysis results of ocean surface current information and the actual measurement results of DVS Current Meter are obtained. The root mean square error of flow velocity less than 10cm/s and the root mean square error of flow direction less than 25 degrees were obtained. It shows that compact surface wave radar can achieve good results and has good detection capability in the west of Guangdong, china. more...
- Published
- 2021
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