Journal articles: 'Dredges'

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Lyubimov, Victor Ivanovich, Nikolay Frolovich Popov, and Grigory Ivanovich Sapunov. "Review and analysis of operation of best domestic and foreign river dredgers." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2020, no. 2 (May 22, 2020): 39–53. http://dx.doi.org/10.24143/2073-1574-2020-2-39-53.

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The article analyzes the development and modernization of energy and technological equipment, as well as soil productivity of dredging projects of both foreign and domestic manufacturers of dredging equipment. The emphasis has been placed on the installation and use of submersible pumps. The productivity of soil dredges has been found to increase due to changes in the design of soil sampling devices and soil pumps. The main characteristics of the American river dredgers with hydraulic cultivators and domestic river diesel dredgers with hydraulic soil cultivators have been considered and evaluated. The designs of the dredgers built in France and the Netherlands have been studied. To compare the technical and economic parameters of the standard type Beaver1600 dredger and the 82080-800 m3/h project domestic dredger there were carried out calculations by the specialists of Volzhskiy State University of Water Transport. There has been illustrated the layout of the TRN-3000 dredge pump (France) including a control cabin, a milling cultivator, a frame of a soil intake device, a submersible soil pump, an anchor support, etc.; layout of the KhAM-219 dredger (Netherlands); layout of Ellicott dredger (USA); layout of a domestic 350-50LPG dredger based on class 350-50L dredgers; a suction pump S-55P; layout of the Benoto dredger (France) including a mechanical cultivator, a soil pump, a hydraulic pump of a soil pump, a frame and a hydraulic cylinder for raising and lowering the frame. It has been inferred that the domestic dredgers are not inferior to the foreign models, taking into account that they are equipped with a new type of domestic rotary-bucket cultivator for working on inland waterways of Russia. The financial assessment of the construction of new domestic dredgers has been carried out.

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Gaspar, M. B., F. Leitão, M. N. Santos, L. Chícharo, M. D. Dias, A. Chícharo, and C. C. Monteiro. "A comparison of direct macrofaunal mortality using three types of clam dredges." ICES Journal of Marine Science 60, no. 4 (January 1, 2003): 733–42. http://dx.doi.org/10.1016/s1054-3139(03)00023-7.

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Abstract The white clam Spisula solida is harvested along the entire coast of Portugal using mechanical dredges. In this study, the total direct mortality of the macrobenthic community caused by three types of clam dredges (north dredge—ND, traditional dredge—TD, and the metallic grid dredge—GD) used in the S. solida fishery was determined and compared. The relationship between mortality and catching efficiency for each type of dredge was also assessed. Our results showed significant differences for total direct mortality between the ND and both the GD and TD dredges. This difference was largely attributed to the mortality of animals that died in the dredge track as a direct result of the physical damage inflicted by the dredge passing. It was also found that the damage to uncaught individuals is directly related to gear efficiency. The lower catching efficiency of the ND (64%) led to a higher proportion of damaged individuals being left in the dredge path, when compared with the more efficient GD (98%) and TD (90%) dredges. Short and long-term implications of the impact of dredging on the composition of benthic communities are discussed. From fisheries management and ecological points of view, there are obvious advantages to introduce into the bivalve dredge fisheries more efficient and selective dredges in order to reduce the number of damaged individuals and by-catch, and consequently decreasing the impact on the macrobenthic communities.

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Ouwerkerk, M. R., P. R. H. Verbeek, and T. Schut. "A NEW TOOL FOR LARGE-SCALE OIL COMBAT." International Oil Spill Conference Proceedings 1995, no. 1 (February 1, 1995): 855B—857. http://dx.doi.org/10.7901/2169-3358-1995-1-855b.

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ABSTRACT Trailing suction hopper dredges maintain ports and their entrance channels around the world. Several of these dredges have already operated as oil spill cleanup vessels as a secondary assignment. Different types of available oil spill response systems were applied. Recent developments allow these dredges to use their own dredge pumps, making these vessels by far the largest capacity oil spill cleanup vessels available in the world. The add-on system requires no modifications of the vessel and a relatively low investment. Tests have documented very good performance.

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Alessi, Marissa A., Peter G. Chirico, Sindhuja Sunder, and Kelsey L. O’Pry. "Detection and Monitoring of Small-Scale Diamond and Gold Mining Dredges Using Synthetic Aperture Radar on the Kadéï (Sangha) River, Central African Republic." Remote Sensing 15, no. 4 (February 7, 2023): 913. http://dx.doi.org/10.3390/rs15040913.

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Diamond and gold mining has been practiced by artisanal miners in the Central African Republic (CAR) for decades. The recent introduction of riverine dredges indicates a transition from artisanal/manual digging and sorting techniques to small-scale mining methods. This study implements a remote sensing analysis of Synthetic Aperture Radar (SAR) data to map gold and diamond dredges operating on the Kadéï (Sangha) river in the CAR. Riverine vessels are identified in Sentinel-1 SAR data between 2015 and 2019, and their activity levels are mapped over time. The number of active dredges identified on the river increased over the five years studied, with the largest increase occurring between 2016 and 2017. Detailing a method for mapping and monitoring riverine diamond and gold dredge mining is an important step in keeping up with evolving technologies and new areas of mineral exploitation and in helping address concerns over resource governance in remote and conflict-prone terrain. The use of SAR technology, with its weather-independence, broad coverage, and available wavelength combinations, allows for higher temporal resolution and improved vessel detection in the monitoring of small-scale mining (SSM) dredges.

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Currie, David R., and Gregory D. Parry. "Impacts and efficiency of scallop dredging on different soft substrates." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 4 (April 1, 1999): 539–50. http://dx.doi.org/10.1139/f98-194.

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Impacts of scallop dredges and their efficiency were examined experimentally in three areas with different soft substrates in Port Phillip Bay, southeastern Australia. Physical and biological changes were measured on large (600 × 600 m) experimental plots that were dredged with an intensity and duration similar to normal fishing operations. Dredges were most efficient on soft, flat, muddy sediments (51-56% of commercial-sized scallops caught) and least efficient on firm, sandy sediments with more topographic variation (38-44%). Dredging flattened all plots, but changes to topography were most apparent on plots dominated initially by callianassid mounds. Dredges caught predominantly the scallop Pecten fumatus, and damage to bycatch species was slight, except for high mortality rates (>50%) of spider crabs and the probable mortality of many discarded ascidians. Changes to benthic community structure caused by scallop dredging were small compared with differences between study areas, and even marked reductions in the size and longevity of scallops over the last two decades may not be due entirely to dredging. The recent cancellation of all scallop dredging licences offers a unique opportunity to determine the contribution of scallop dredging to ecological changes in the bay over the past 30 years.

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Vasconcelos, Paulo, António Morgado-André, Carlos Morgado-André, and Miguel B. Gaspar. "Shell strength and fishing damage to the smooth clam (Callista chione): simulating impacts caused by bivalve dredging." ICES Journal of Marine Science 68, no. 1 (October 8, 2010): 32–42. http://dx.doi.org/10.1093/icesjms/fsq149.

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Abstract Vasconcelos, P., Morgado-André, A., Morgado-André, C., and Gaspar, M. B. 2011. Shell strength and fishing damage to the smooth clam (Callista chione): simulating impacts caused by bivalve dredging. – ICES Journal of Marine Science, 68: 32–42. The smooth clam Callista chione is exploited by a fleet of dredgers along the southwestern coast of Portugal and suffers from a high incidence of shell damage. The force required to break C. chione shells in relation to fishing impacts and dredge damage is quantified. Fishing trials and shell-strength measurements (compression and compaction experiments) were performed to determine whether shell damage was attributable to the direct impact of the dredge teeth or to sediment compaction. A three-dimensional model of C. chione was subjected to simulated force by the finite element method. Analyses of damage areas and breakage patterns revealed two groups of samples, one containing the samples from compression experiments and another with the samples from dredging and compaction experiments, suggesting that most shell damage was attributable to compaction within the sediment. Information is provided to help improve the design of bivalve dredges, by increasing both length and angle of the dredge teeth, which would reduce the compaction force and distribute it differentially within the sediment, forcing upward movement of the bivalves.

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Greene, Paul, George Follett, and Clint Henker. "Munitions and Dredging Experience on the United States Coast." Marine Technology Society Journal 43, no. 4 (October 1, 2009): 127–31. http://dx.doi.org/10.4031/mtsj.43.4.2.

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AbstractA number of dredging projects have unknowingly and unfortunately encountered munitions and explosives of concern (MEC). MEC have been discovered on dredges (e.g., in dragheads, cutterheads, pump casings) and at the dredged material placement site. Detonations have occurred that have either damaged the dredge plant or have even sunk the dredging vessel. A number of recent dredging projects have proactively addressed MEC issues before the start of construction, thereby greatly reducing overall risk and MEC cleanup costs. This paper explains common dredging equipment, discusses techniques useful in reducing the inherent risks of dredging in sediments containing MEC, and discusses lessons learned during various dredging projects involving MEC.Application of MEC avoidance and exclusion techniques during dredging operations is minor compared to the enormous cost of post-dredging MEC cleanup. Most importantly, it is possible to avoid exposing the public to explosive safety hazards and minimize those to workers with proper planning and execution.

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Thorarinsdóttir, Gudrun G., Larry Jacobson, Stefan Áki Ragnarsson, Elena Guijarro Garcia, and Karl Gunnarsson. "Capture efficiency and size selectivity of hydraulic clam dredges used in fishing for ocean quahogs (Arctica islandica): simultaneous estimation in the SELECT model." ICES Journal of Marine Science 67, no. 2 (September 23, 2009): 345–54. http://dx.doi.org/10.1093/icesjms/fsp236.

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AbstractThorarinsdóttir, G. G., Jacobson, L., Ragnarsson, S. Á., Garcia, E. G., and Gunnarsson, K. 2010. Capture efficiency and size selectivity of hydraulic clam dredges used in fishing for ocean quahogs (Arctica islandica): simultaneous estimation in the SELECT model. – ICES Journal of Marine Science, 67: 345–354. Estimates of capture efficiency and size selectivity for commercial dredges are important in estimating stock biomass and setting catch limits for the ocean quahog off Iceland and the United States. Ocean quahogs are long-lived, slow-growing, and sensitive to overharvest resulting from poor estimates of capture efficiency and stock biomass. Capture efficiency and size selectivity were estimated simultaneously in mixed-effect SELECT models using diver and commercial dredge experiment data from the shallow-water habitats off Iceland. Estimated capture efficiency for the commercial dredge E = 92% (CV = 8%) was high for large [107.5 mm shell length (SL)] ocean quahogs. Size selectivity followed an ascending logistic curve, with L50 = 70.5 mm SL (CV 4%), a selectivity range of 17.6 mm SL, and substantial variability among experimental dredge tows. Estimated capture efficiency was higher than that for ocean quahogs in US waters, possibly because of the deep habitats off the United States or uncertainty about dredge position during US depletion experiments. Scaling maximum selectivity from the SELECT model to one reduces correlations between size-selectivity and capture-efficiency parameters and may enhance the utility of selectivity estimates in stock assessment modelling. Our experimental and modelling approach may be useful for studies with other non-mobile benthic species.

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Veale, L. O., A. S. Hill, S. J. Hawkins, and A. R. Brand. "Distribution and damage to the by-catch assemblages of the northern Irish Sea scallop dredge fisheries." Journal of the Marine Biological Association of the United Kingdom 81, no. 1 (February 2001): 85–96. http://dx.doi.org/10.1017/s0025315401003435.

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The major by-catch species retained during twice yearly dredge surveys of great scallop, Pecten maximus, and queen scallop, Aequipecten opercularis, (both Mollusca: Pectinidae) populations on 13 fishing grounds in the northern Irish Sea, over a period of five years, were identified and enumerated. Additionally, the damage sustained by the by-catch was assessed and related to a range of physical parameters recorded during the survey. A number of species captured in the spring-toothed dredges exhibited differences in abundance and damage sustained between years, and also between the start and end of the closed season for great scallop fishing (1 June–31 October). The by-catch assemblage varied geographically, dependent upon the underlying community structure, as well as putative factors including gear efficiency and substratum type. Two clear assemblage types were identified by multivariate analysis, one to the south-west of the Isle of Man, the other covering fishing grounds to the north, east and south of the island. There is a hierarchy of species sensitivity to damage in great and queen scallop dredges, probably related to morphological and behavioural characteristics. This selective mortality of a fraction of the community may have long-term implications at the ecosystem level. The degree of damage sustained by many species is related to both the volume of stones retained in the dredge, and the total volume of the catch (dredge fullness). If these were reduced, the overall magnitude of incidental by-catch mortality would be lower.

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10

Malanga, G. "The French Dredges." Literary Imagination 4, no. 3 (January 1, 2002): 436–37. http://dx.doi.org/10.1093/litimag/4.3.436.

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Dudinskii, Fedor, Boris Talgamer, and Nikolai Murzin. "Justifying the parameters of dredging in various types of stopes and massive productive strata." Izvestiya vysshikh uchebnykh zavedenii Gornyi zhurnal, no. 3 (May 14, 2020): 5–14. http://dx.doi.org/10.21440/0536-1028-2020-3-5-14.

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Introduction. Due to a wide variety of placer dredging conditions, traditional methods of dredging parameters calculation do not always take into account all aspects of productive strata mining. It is first of all true for deep placers operation and mining with side cuts. Research aim is to improve the methods of calculating dredging parameters and the capacity of pilesupported bucket chain dredgers. Methodology. Existing methods of calculating dredging parameters and dredgers capacity do not take into account the applied mining method, stope type, and upper stope cave-in conditions. The indicated factors greatly influence the parameters of productive strata excavation and washery refuse disposal. Taking these ISSN 0536-1028 «Известия вузов. Горный журнал», № 3, 2020 13 factors into account makes it possible to forecast the indicators of the pile-support dredgers more accurately. Results. Investigation of some aspects of dredging trenches and side cuts has made it possible to establish the dependence of dredger maneuvering angle in pit face and capacity on cutting depth when mining massive productive strata; spoil dumps parameters dependence on the type of stoping; the interrelation between the daily capacity and the width of the front bank under various vertical distribution of rock. The indicated dependences allow to determine dredging parameters and indicators for particular conditions. Summary. The proposed approach, which calculates dredging parameters when using side cuts and when mining deep placers with non-uniform thickness of sands, makes it possible to calculate the chips size, buckets filling ratio and sand fragmentation ratio in a more substantiated way; it makes it possible to more effectively manage the process of sand mining, thus increasing the capacity of dredges.

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Neitman, L. N., M. M. Fridman, N. N. Kozhevnikov, and F. P. Tsurgan. "Equipping dredges with submersible pumps." Hydrotechnical Construction 28, no. 1 (January 1994): 53–57. http://dx.doi.org/10.1007/bf01545102.

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Johnsen, Espen, and Alf Harbitz. "Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge." ICES Journal of Marine Science 70, no. 2 (January 17, 2013): 379–86. http://dx.doi.org/10.1093/icesjms/fss202.

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Abstract Johnsen, E., and Harbitz, A. 2013. Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge – ICES Journal of Marine Science, 70: 379–386. The lesser sandeel (Ammodytes marinus) remains burrowed for long periods in the seabed in sandy areas, and its habitat preference is reflected in a large-scale (10 km) patchy distribution in the North Sea. The small-scale spatial structure of sandeels in the seabed is less known. In this study, it was found that sandeel catches in grabs and dredges fit gamma distributions with a common shape parameter on both a 10 m and a 100 m scale. These spatial models were used to examine the catching properties of the dredge, which, in the new ICES sandeel assessment, is used to estimate recruitment and maturity curves. Analyses of the empirical data and simulations of the dredge and grab catch rates show very low dredge catchability (∼5%), but no length-dependent catchability in the dredge was found. However, analyses of the catch rates of parallel dredge hauls indicated increasing dredge catchability with sandeel density. The observed small-scale patchiness and the low and seemingly density-dependent dredge catchability result in biased abundance estimates with low precision. Therefore, we recommend a joint international effort to develop a more catch-efficient sampling dredge, where the effect of density on catchability is further examined.

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Cores, Claudia, Miguel B. Gaspar, and Karim Erzini. "Estimating the density of Pennant's swimming crab, Portumnus latipes (Pennant, 1777) in the swash zone using baited stakes and area of attraction." Journal of the Marine Biological Association of the United Kingdom 99, no. 4 (September 28, 2018): 887–90. http://dx.doi.org/10.1017/s002531541800067x.

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AbstractWe used a new, easy to use, highly selective, low impact and cheap method of sampling in the swash zone of a sandy beach to obtain catch per unit effort data (CPUE) for Pennant's swimming crab, Portumnus latipes (Pennant, 1777). Metal stakes baited with sardines were used to attract the crabs that were caught by hand. Crab density was estimated based on area of attraction and maximum CPUE and compared with estimates from bivalve dredges used at depths from 3 to 6.5 m. The baited stake method gave an estimate of 0.026 crabs m−2, which is comparable to bivalve dredge estimates (0.0059–0.045 crabs m−2). This approach can be used for crustaceans, gastropods and other mobile benthic organisms.

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Roshchupkin, D. V. "Excavation of heavy soils by dredges." Hydrotechnical Construction 21, no. 4 (April 1987): 194–97. http://dx.doi.org/10.1007/bf01429611.

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Ogorodnikov, S. P., N. N. Kozhevnikov, and A. E. Kulakov. "Submersible axial-flow pumps for dredges." Hydrotechnical Construction 29, no. 10 (October 1995): 574–77. http://dx.doi.org/10.1007/bf02443046.

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Pfarrer, V. H. "THE HYDRAULIC DREDGING AND PUMPING OF LAKE AREA DEPOSITS." Coastal Engineering Proceedings 1, no. 4 (January 1, 2000): 21. http://dx.doi.org/10.9753/icce.v4.21.

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First let me say that it is a sincere pleasure and an honor to address such a distinguished audience. More people should be made aware of the work that you are doing in the protection of our shores and coastline. It is a great satisfaction to me to he associated with an industry that is instrumental in rebuilding our shores along the lines of your extensive studies and recommendations. I recall laboring over the trochoidal wave theory in my study of naval architecture quite a few years ago. Frankly, it is not used very much in dredge design except in the larger molded form sea going hopper dredges. There is no doubt that you have made great strides in the theory of wave motion and transmitted energy since that time.

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Arcandra, _., Robert E. Randall, and Moo H. Kim. "Dynamic Analysis of a Semisubmersible-type Bucket Ladder Dredge." Marine Technology and SNAME News 36, no. 03 (July 1, 1999): 143–56. http://dx.doi.org/10.5957/mt1.1999.36.3.143.

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A semisubmersible-type bucket ladder dredge is a candidate to satisfy the need of the Indonesian tin mining company, PT Timah, to recover tin deposits in water depths of 50 m and deeper. Their current vessel is a barge-type bucket ladder dredge capable of operating in depths shallower than only 30 m. In order to evaluate the dredging capability in 50 m water depth, a dynamic analysis of both semisubmersible-type and barge-type bucket ladder dredges was conducted. The vessel was designed by modifying an existing semisubmersible platform used in the oil and gas industry, while the barge-type used is a conventional bucket ladder dredge. Hydrodynamic coefficients, wave forces, and response amplitude operators (RAOs) of both vessels were computed by using the 3D linear diffraction-radiation software WAMIT. The response spectra of the vessels were obtained in head, quarter, and beam seas of sea state 4. The effect of mooring stiffness was also investigated. Besides modeling the system with low stiffness, such as a catenary mooring, the dynamic analysis was also conducted for the free-floating condition. Finally, the motion performance for the two vessels was compared for various sea conditions, and it is shown that the semisubmersible-type bucket ladder dredge performs better with smaller responses in the selected sea conditions expected in water depths greater than 50 m.

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Harms, CA, SM Boylan, BA Stacy, JF Beasley, D. García-Párraga, and MH Godfrey. "Gas embolism and massive blunt force trauma to sea turtles entrained in hopper dredges in North and South Carolina, USA." Diseases of Aquatic Organisms 142 (December 17, 2020): 189–96. http://dx.doi.org/10.3354/dao03542.

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Decompression sickness (DCS) has been described mainly in loggerhead turtles Caretta caretta bycaught in trawls and gillnets. Here we present cases of gas emboli (GE) in 8 green turtles Chelonia mydas and 2 Kemp’s ridleys Lepidochelys kempii entrained in hopper dredges that were working at 8.8-15.2 m depths during shipping channel maintenance or beach renourishment activities. Turtle weights ranged from 2.2 to 6.7 kg. All were found alive with blunt force injuries from passage through the dredge and were taken to rehabilitation facilities. Four green turtles died or were euthanized within 24 h. Six turtles survived. Radiographic or ultrasonographic evidence of GE was detected in 4 turtles, including 3 mortalities. Computed tomography (CT) revealed perirenal and cervical GE in 4 turtles, including 1 mortality. No GE were detected in 2 of the survivors. Upon necropsy, GE were found in mesenteric vessels, the right atrium, and kidneys. Histopathology confirmed that tissues were in a good state of preservation without evidence of bacterial overgrowth or putrefactive gas formation. Death likely resulted primarily from massive tissue trauma from the dredge, but moderate GE could have led to DCS and complicated recovery. The surviving turtles weighed less than those that did not survive. Besides hypothesized stress/exercise-induced circulatory changes of blood through the lungs and pressure reduction of forced surfacing from depth, drastic pressure change within the dredge pipes before and after the pump could contribute to GE. Hopper dredge entrainment is an additional cause of GE and potential DCS in sea turtles.

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Child, C. Allan, and G. R. Harbison. "A Parasitic Association Between a Pycnogonid and a Scyphomedusa in Midwater." Journal of the Marine Biological Association of the United Kingdom 66, no. 1 (February 1986): 113–17. http://dx.doi.org/10.1017/s0025315400039680.

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The feeding habits and host specificities of the Pycnogonida are poorly known. These usually small, cryptically coloured animals are difficult to observe alive and are mostly collected fortuitously in gross samples taken from trawls and dredges. Any association between the pycnogonids and their food is disrupted in the trawl. Further, the possibility that some of the pycnogonids may have been captured in the water column rather than on the bottom cannot be ascertained from trawl and dredge samples. King (1973) lists only twelve records of pycnogonids actually seen browsing on food organisms. Most occur on hydroids and other cnidarians, and all are from benthic habitats. In more recent papers, Stock reports a pycnogonid seen on a brittle star in the Seychelles (1979), feeding preferences of pycnogonids on benthic cnidarians (1978), and an association between a pycnogonid and a starfish from the Philippines (1981).

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Castro, Filipe. "Arade River Archaeological Complex: Dredges and Archaeology." International Journal of Nautical Archaeology 34, no. 1 (April 2005): 51–61. http://dx.doi.org/10.1111/j.1095-9270.2005.00043.x.

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Kozhevnikov, N. N. "Improving the wear resistance of suction dredges." Hydrotechnical Construction 29, no. 3 (March 1995): 143–47. http://dx.doi.org/10.1007/bf01545806.

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Cathcart, R. B. "Kra Canal (Thailand) excavation by nuclear-powered dredges." International Journal of Global Environmental Issues 8, no. 3 (2008): 248. http://dx.doi.org/10.1504/ijgenvi.2008.018639.

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Ogorodnikov, S. P., I. I. Mikheev, A. E. Kulakov, and N. N. Kozhevnikov. "Intake devices for dredges with submersible suction pumps." Hydrotechnical Construction 24, no. 6 (June 1990): 372–74. http://dx.doi.org/10.1007/bf01433312.

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Mikheev, I. I., V. I. Goryachev, and T. P. Kuznetsova. "Cutter Heads of Suction Dredges for Underwater Excavation." Power Technology and Engineering 51, no. 1 (May 2017): 58–60. http://dx.doi.org/10.1007/s10749-017-0783-2.

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Ivanov, A. E. "Output of suction dredges with respect to solids." Hydrotechnical Construction 26, no. 10 (October 1992): 677–80. http://dx.doi.org/10.1007/bf01544772.

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BAETA, MARC, AROA NAVARRETE, and MANUEL BALLESTEROS. "First description of a new worm bait fishery in the NW Mediterranean Sea." Mediterranean Marine Science 20, no. 2 (May 29, 2019): 302. http://dx.doi.org/10.12681/mms.19959.

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Most commercial clam stocks in the NW Mediterranean Sea have collapsed over the last few decades and, as a result, most clam dredge fishermen have been forced to leave the fishing sector. Recently, in order to sustain their economic activity, some fishermen have modified dredges to target sea worms to sell as bait for recreational fisheries. This study provides the first information about this new worm bait fishery on the Catalan Maresme coast (NE Spain). The local administration has regulated only a few aspects of the fishery: users (2 boats), geographical limits (40 km; between 0-7 m depth), fishing time (6:00-14:00) and dredge design (the same as those used for smooth clams but with interior structures to retain worms and an open back). Fishing activity takes place throughout the year. Fishermen target three worm bait species: Sigalion squamosus, Ophelia neglecta and Halla parthenopeia. A mean of 233.37 individuals of S. squamosus, 167.93 of O. neglecta and 2.17 of H. parthenopeia are gathered per boat and day. Worm baits are sold directly to local recreational fishing shops as a quality product at the highest prices on the market. This fishery has a high social and economic value for the Maresme coast, helping to maintain small-scale fishermen jobs with an economic benefit similar to clam fishing.

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Firdaus, Aden, Muhammad Rizkiansyah, and Yessi Nirwana. "Analisis Perbandingan Biaya pada Pekerjaan Pengerukan di Alur Pelabuhan Bandar Bakau Jaya Banten." Jurnal Rekayasa Hijau 4, no. 2 (August 7, 2020): 62–71. http://dx.doi.org/10.26760/jrh.v4i2.15-23.

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ABSTRAKPelabuhan Bandar Bakau Jaya yang terletak di Provinsi Banten saat ini dapat melayani kapal yang berjenis 5.000 DWT, dan rencananya akan melayani kapal 10.000 DWT. Pekerjaan pengerukan akan dilakukan pada Alur Pelabuhan dengan dimensi panjang 2.391 m dengan jenis tanah adalah tanah halus berpasir. Tujuan dari penelitian ini adalah membandingkan biaya dan waktu pelaksanaan dari masing- masing jenis kapal keruk yang dapat melakukan pekerjaan pengerukan dengan kondisi tanah yang ada di alur pelabuhan. Metode yang digunakan adalah dengan memperhitungkan berapa lama waktu pekerjaan pengerukan sehingga didapatkan biaya dari masing-masing jenis kapal keruk. Hasil dari analisis didapatkan 3 jenis kapal keruk yaitu, TSHD dalam waktu 2,11 bulan dan biaya Rp27.316.912.819,63, SD dalam waktu 8,34 bulan dan biaya Rp27.887.202.652,35, dan CSD dalam waktu 6,08 bulan dan biaya Rp37.995.671.214,00. Jenis kapal keruk yang paling efisien untuk pekerjaan pengerukan di alur pelabuhan ini adalah TSHD dengan 7 tugboat dan barge.Kata kunci: pengerukan, alur pelayaran, kapal keruk ABSTRACTBandar Bakau Jaya Port, located in Banten Province, currently serves 5,000 DWT vessels, and it is planned to serve 10,000 DWT vessels. Dredging work will be carried out on the Port Channel with a dimension of 2,391 m in length with a fine sandy soil type. The purpose of this study is to compare the cost and implementation time of each type of dredger that can carry out dredging work with existing soil conditions in the port channel. The method used is to calculate how long the dredging work is so that the cost of each type of dredger is obtained. The results of the analysis found 3 types of dredges namely, TSHD in 2.11 months and costs Rp27,316,912,819.63, SD in 8.34 months and costs Rp27,887,202,652.35, and CSD in 6, 08 months and costs Rp37,995,671,214.00. The most efficient type of dredger for this work is TSHD with 7 tugboats and barges.Keywords: dredging, fairway, dredger

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Firdaus, Aden, Muhammad Rizkiansyah, and Yessi Nirwana. "Analisis Perbandingan Biaya pada Pekerjaan Pengerukan di Alur Pelabuhan Bandar Bakau Jaya Banten." Jurnal Rekayasa Hijau 4, no. 2 (August 7, 2020): 62–71. http://dx.doi.org/10.26760/jrh.v4i2.62-71.

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ABSTRAKPelabuhan Bandar Bakau Jaya yang terletak di Provinsi Banten saat ini dapat melayani kapal yang berjenis 5.000 DWT, dan rencananya akan melayani kapal 10.000 DWT. Pekerjaan pengerukan akan dilakukan pada Alur Pelabuhan dengan dimensi panjang 2.391 m dengan jenis tanah adalah tanah halus berpasir. Tujuan dari penelitian ini adalah membandingkan biaya dan waktu pelaksanaan dari masing- masing jenis kapal keruk yang dapat melakukan pekerjaan pengerukan dengan kondisi tanah yang ada di alur pelabuhan. Metode yang digunakan adalah dengan memperhitungkan berapa lama waktu pekerjaan pengerukan sehingga didapatkan biaya dari masing-masing jenis kapal keruk. Hasil dari analisis didapatkan 3 jenis kapal keruk yaitu, TSHD dalam waktu 2,11 bulan dan biaya Rp27.316.912.819,63, SD dalam waktu 8,34 bulan dan biaya Rp27.887.202.652,35, dan CSD dalam waktu 6,08 bulan dan biaya Rp37.995.671.214,00. Jenis kapal keruk yang paling efisien untuk pekerjaan pengerukan di alur pelabuhan ini adalah TSHD dengan 7 tugboat dan barge.Kata kunci: pengerukan, alur pelayaran, kapal keruk ABSTRACTBandar Bakau Jaya Port, located in Banten Province, currently serves 5,000 DWT vessels, and it is planned to serve 10,000 DWT vessels. Dredging work will be carried out on the Port Channel with a dimension of 2,391 m in length with a fine sandy soil type. The purpose of this study is to compare the cost and implementation time of each type of dredger that can carry out dredging work with existing soil conditions in the port channel. The method used is to calculate how long the dredging work is so that the cost of each type of dredger is obtained. The results of the analysis found 3 types of dredges namely, TSHD in 2.11 months and costs Rp27,316,912,819.63, SD in 8.34 months and costs Rp27,887,202,652.35, and CSD in 6, 08 months and costs Rp37,995,671,214.00. The most efficient type of dredger for this work is TSHD with 7 tugboats and barges.Keywords: dredging, fairway, dredger

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Leitão, Francisco, Pedro Range, and Miguel Baptista Gaspar. "SURVIVAL ESTIMATES OF BYCATCH INDIVIDUALS DISCARDED FROM BIVALVE DREDGES." Brazilian Journal of Oceanography 62, no. 4 (December 2014): 257–63. http://dx.doi.org/10.1590/s1679-87592014067006204.

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The fate of released bycatch is an issue of great interest for fisheries research and management. Survival experiments were carried out to assess the survival capacity of animals damaged and discarded during clam dredging operations. Three common bycatch species, two fish (Trachinus vipera; Dicologlossa cuneata) and one crab (Polybius henslowii), were collected during the sorting of catches from a commercial dredging boat. An arbitrary score scale was used to quantify the type and extent of damage to the organisms. Onboard, damaged individuals were placed in tanks containing seawater which were subsequently transferred to the laboratory. Survival experiments were conducted during the subsequent 48h. D. cuneata exhibited the lowest mortality after 48h (54%), followed by P. henslowii (65%) and T. vipera (81%). Despite the magnitude of the percentage mortalities determined, the average number of individuals estimated to die during a 15 minutes tow (standard commercial fishing time) was relatively small: 1.2, 3.24 and 11 for D. cuneata, T. vipera and P. henslowii, respectively. Nevertheless, when these figures are extrapolated to cover all the dredging fleet the impact of this practice on the populations of the species studied can be significant, particulary for D. cuneata.

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Gilkinson, Kent D., Donald C. Gordon, Kevin G. MacIsaac, David L. McKeown, Ellen L. R. Kenchington, Cynthia Bourbonnais, and W. Peter Vass. "Immediate impacts and recovery trajectories of macrofaunal communities following hydraulic clam dredging on Banquereau, eastern Canada." ICES Journal of Marine Science 62, no. 5 (January 1, 2005): 925–47. http://dx.doi.org/10.1016/j.icesjms.2005.03.009.

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Abstract A hydraulic clam dredging experiment, designed to mimic offshore commercial dredging practices, was carried out at a depth of approximately 70 m on a sandy seabed on Banquereau, on the Scotian Shelf, eastern Canada. The experiment was designed to study the separate and combined effects of dredging through three treatment boxes (Dredging Only, Dredging and Discarding, Discarding Only) and two spatially separated reference boxes. In all, 270 taxa were identified from grab samples. Of these, four bivalves are targeted in the commercial fishery (Arctica islandica, Cyrtodaria siliqua, Mactromeris polynyma, and Serripes groenlandicus) while 266 taxa were non-target species. Sample biomass was dominated by the propellerclam, C. siliqua, and the echinoderm, Echinarachnius parma, while the polychaete, Spiophanes bombyx, was the numerical dominant. The dredges captured 33 invertebrate and two fish taxa, although >80% of the catch biomass comprised propellerclams and echinoderms. Immediately after dredging, most macrofaunal species decreased in abundance, with the greatest declines inside dredge furrows (which covered 53–68% of the area inside the dredged boxes). Large numbers of propellerclams were excavated to the seabed surface, with a large proportion showing massive damage. There were few signs of discards on the sediment surface. Recovery trajectories of target and non-target species were followed for 2 years. Following initial declines in abundance and biomass of most taxa immediately after dredging, there were marked increases in abundance of polychaetes and amphipods after 1 year. Two years after dredging, abundances of opportunistic species were generally elevated by ≫100% relative to pre-dredging levels. Two years after dredging, average taxonomic distinctness had decreased (i.e. taxonomic relatedness between species had increased) due, in part, to increased numbers of species of certain polychaetes and amphipods, while communities had become numerically dominated (50–70%) by S. bombyx. It is concluded that the disturbed community was still in the colonizing phase 2 years after dredging. The mobile brittlestar, Ophiura sarsi, displayed increases in abundance ranging from 200% to 300% in the dredged and reference boxes over the 2-year post-dredging. A similar response of non-target macrofauna in the reference boxes suggests, possibly, a coincident natural recruitment pulse. Dredging resulted in pronounced, sustained reductions in biomass (up to 67%) of the target bivalves with no signs of recovery after 2 years. Recruitment of target bivalves (>1-mm shell length) was very low throughout the experimental area during this interval.

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MITUHASI, Takahisa, Toshihide KITAKADO, Fuxiang HU, and Tadashi TOKAI. "Modelling the contact probability and size-selectivity of toothed dredges." Fisheries Science 71, no. 4 (August 2005): 703–12. http://dx.doi.org/10.1111/j.1444-2906.2005.00996.x.

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O'Neill, F. G., M. Robertson, K. Summerbell, M. Breen, and L. A. Robinson. "The mobilisation of sediment and benthic infauna by scallop dredges." Marine Environmental Research 90 (September 2013): 104–12. http://dx.doi.org/10.1016/j.marenvres.2013.06.003.

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34

Kozhevnikov, N. N., and M. S. Triandafilov. "Improving the delivery of suction-tube dredges and hydrotransport parameters." Hydrotechnical Construction 24, no. 11 (November 1990): 697–702. http://dx.doi.org/10.1007/bf01423889.

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35

Ogorodnikov, S. P., I. I. Mikheev, and A. E. Kulakov. "Optimization of the mud intakes of dredges with submersible pumps." Hydrotechnical Construction 21, no. 7 (July 1987): 432–36. http://dx.doi.org/10.1007/bf01427276.

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36

Freidin, V. M., T. I. Adam'yants, and N. N. Kozhevnikov. "Prospects of using grab dredges for excavating gravel-pebble deposits." Hydrotechnical Construction 22, no. 3 (March 1988): 155–57. http://dx.doi.org/10.1007/bf01441068.

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Kozhevnikov, N. N., Ya Ya Urisman, and M. M. Fridman. "Development and implementation of domestic suction dredges with submersible pumps." Power Technology and Engineering 40, no. 6 (November 2006): 325–29. http://dx.doi.org/10.1007/s10749-006-0070-0.

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Anjos, Mariana, Fábio Pereira, Paulo Vasconcelos, Sandra Joaquim, Domitília Matias, Karim Erzini, and Miguel Gaspar. "Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)." Scientia Marina 82, S1 (December 20, 2018): 75. http://dx.doi.org/10.3989/scimar.04742.08a.

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Although the bivalve dredge used on the Algarve coast (southern Portugal) is highly selective for the target species, in some periods of the year the bycatch can exceed the catch of the commercial species. The present study aimed to quantify the bycatch and discards, estimate damage and mortality, and propose management measures to minimize discards and mortality. A total of 15 fishing surveys (60 tows) were performed using two types of dredges (“DDredge” targeting Donax trunculus and “SDredge” targeting Spisula solida and Chamelea gallina). Of the 85257 individuals (392.4 kg) of 52 taxa that were caught, 73.4% belonged to the target species, 22.1% to commercially undersized target species and 4.5% to bycatch species. Bycatch rates were lower for SDredge (13.5% in number and 6.3% in weight) than for DDredge (46.0% in number and 32.9% in weight). Damage and mortality rates were also lower using SDredge (1.3% and 1.0% of the total catches, respectively) than using DDredge (4.0% and 2.8% of the total catches). Survival experiments revealed the diverse vulnerability of the taxa and confirmed the influence of the damage score on the mortality rate. The results gathered in the present study encourage the adoption of a bycatch reduction device to reduce both direct and indirect mortality.

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Lucchetti, Alessandro, and Antonello Sala. "Impact and performance of Mediterranean fishing gear by side-scan sonar technology." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 11 (November 2012): 1806–16. http://dx.doi.org/10.1139/f2012-107.

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An innovative approach with side-scan sonar was implemented to observe directly during towing operations the behaviour and the performance of hydraulic dredge, Rapido trawl, and two types of Mediterranean bottom trawls. The innovative aspect of the current paper is that a side-scan sonar was used alongside fishing operations when towing was in progress. Based on available literature, the type and level of the physical impact assessed were used to infer biological and ecological consequences caused by the fishing gear. The sonar used in real time can be applied to a wide range of research and management issues, such as the fishing gear impact on benthic ecosystems and the in situ fishing gear performance. We demonstrated that gear type and rigging, together with environmental conditions, are the main factors affecting the disturbance caused by fishing. Hydraulic dredges scrape the surface of the substratum and dig into it by resuspending large amounts of sediment. Rapido trawls used in muddy areas for common sole (Solea solea) dig deeper into the sediment, making furrows up to 10–13 cm deep. The most evident physical effects of trawling were the furrows produced by the otterboards, while other parts of the trawl created only faint marks.

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Urisman, Ya Ya. "Development of Flooded Sand and Gravel Pits by Use of Dredges." Power Technology and Engineering 38, no. 4 (July 2004): 208–11. http://dx.doi.org/10.1023/b:hyco.0000047259.08606.28.

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41

Leotsinidis, Michalis, and Eleni Sazakli. "Evaluating contamination of dredges and disposal criteria in Greek coastal areas." Chemosphere 72, no. 5 (June 2008): 811–18. http://dx.doi.org/10.1016/j.chemosphere.2008.02.049.

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Qi, Qiang, Feifei Qiao, Wenyuan Wang, Zijian Guo, and Ying Jiang. "A evaluation and selection model of dredger considering marine ecological environment and dredger performance." E3S Web of Conferences 294 (2021): 06001. http://dx.doi.org/10.1051/e3sconf/202129406001.

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There will be total suspended solids in port dredging, which will affect aquatic organisms and water quality. Therefore, with the Green Port becoming the core concept of port development, it is necessary to consider the impact of dredging on marine ecological environment when selecting dredgers. In this paper, the calculation method of biomass loss caused by dredging is proposed, and the biomass loss is taken as the evaluation index to establish a dredger selection model considering marine ecological environment and dredger performance. The dredger selection model uses the fuzzy synthetic evaluation method based on norm grey relational grade to evaluate and select dredgers quantitatively, avoiding the influence of subjective factors on dredger selection. Finally, the feasibility of dredger selection model is verified by a practical dredging engineering and the results indicate that the dredger selection model can serve as a scientific basis for the construction of ecological port and the protection of marine environment.

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Konter, Jasper G., Valerie A. Finlayson, Jacqueline Engel, Matthew G. Jackson, Anthony A. P. Koppers, and Shiv K. Sharma. "Shipboard Characterization of Tuvalu, Samoa, and Lau Dredge Samples Using Laser-Induced Breakdown Spectroscopy (LIBS)." Applied Spectroscopy 73, no. 6 (April 22, 2019): 623–37. http://dx.doi.org/10.1177/0003702819830793.

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Chemical analysis using laser-induced breakdown spectroscopy (LIBS) is well suited for field applications and was applied here for shipboard characterization of a large sample set during the RR1310 rock dredging expedition to the Tuvalu Seamounts. Although recently the most common data treatment for LIBS has consisted of a partial least squares approach to define sample groupings, we show that quantitative data of useful quality can be obtained with a univariate approach. Here, our analysis goal was a quantitative comparison of the total alkali (Na2O + K2O) versus silica (SiO2) contents of 586 representative dredge samples with known ranges in common rock types. Out of those samples, >400 form a single large group of alkalic basalts with minor basanites/tephrites (SiO2: 43–48 wt%, Na2O + K2O: 3–5 wt%), similar to known shield-stage compositions of the Rurutu and Samoa hotspots in the sampling area. In contrast, several dredge hauls contain samples with compositions that do not overlap with the majority of samples. This includes three dredges performed on the northern boundary of the Lau Basin that contain similar SiO2 compositions, but slightly higher total alkali (Na2O+K2O) content. Despite this difference, they classify as basanite/tephrite, similar to a subset of the main group. More importantly, similar compositions were previously reported from the same tectonic boundary, ascribed to hotspot mantle source material mixed into the Lau Basin back-arc. Although the quality of the compositional data suffices to enable sample selection for time-intensive analyses, higher precision is required for more in-depth petrogenetic interpretation. Error analysis based on repeat standard measurements suggests averaging 100 spectra per sample is optimal here, while use of a higher resolution spectrometer, together with better laser control, would improve results and interpretations.

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Dobkowski, Aleksandra H. "Dumptrucks versus dredges: An economic analysis of sand sources for beach nourishment." Coastal Management 26, no. 4 (January 1998): 303–14. http://dx.doi.org/10.1080/08920759809362361.

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Zhuang, Haifei, Mingming Liu, and Yongding Wu. "Study on Impeller Configuration Strategy of Dredger Pump with Different Conveying Distance." Journal of Physics: Conference Series 2329, no. 1 (August 1, 2022): 012019. http://dx.doi.org/10.1088/1742-6596/2329/1/012019.

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Abstract For DN850 dredge pumps of 3,500 m3/h series cutter suction dredger, on the premise of not changing the impeller size, by changing the parameters of impeller blade to reduce the head of dredge pump, special new impellers for inboard pump and submerged pump are designed; The flow field of the dredge pump is analyzed by numerical simulation. There is no vortex in the impeller channel and near volute tongue, which indicates that the hydraulic performance is excellent; At the flow rate of 10,000 m3/h, compared with the original impeller, the head of the two pumps in series with new impellers is reduced by 23 m, and the efficiency is close to that before modification, reaching more than 85%; This paper analyzes the matching between the dredger pump and the pipeline under three kinds of common sandy mud. By comparing the unit power consumption and productivity, it obtains the suitable conveying distance range of special new impellers of dredger pumps, and forms the impeller configuration scheme of 3,500 m3/h series cutter suction dredger with different conveying distance, which provides guidance for dredging engineering.

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Ren, Yu, Lina Duan, Jiabi Song, Xingxing Wang, Nan Zheng, and Huiling Jing. "Clinical Research Progress of Fire Needle Acupuncture in the Treatment of Alopecia Areata." Journal of Clinical and Nursing Research 6, no. 3 (May 19, 2022): 128–31. http://dx.doi.org/10.26689/jcnr.v6i3.3900.

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Alopecia areata is a common disease in dermatology. It is a localized non-inflammatory alopecia that occurs in the head. Its etiology is unclear, but it is thought to be related to a number of factors. At present, there are many methods of treatment with different curative effects. Fire needle acupuncture directly acts on skin lesions, dredges meridians, and regulates Qi and blood. It has a good curative effect. This paper reviews current research progress of fire acupuncture in the treatment of alopecia areata, in order to provide some diagnostic and treatment suggestions for the management of alopecia areata.

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Lian, Jinghua, Genping Lei, and Sheng Dong. "Understanding the Use of Radix Astragali Seu Hedysari in the Treatment of Edema Due to Renal Diseases." Proceedings of Anticancer Research 5, no. 5 (September 24, 2021): 11–14. http://dx.doi.org/10.26689/par.v5i5.2513.

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Radix Astragali seu Hedysari is warm in nature and slightly sweet in taste. It belongs to the lung, spleen, and kidney meridians. It passes through a waterway, dredges the triple energizer, and has a significant effect on edema due to renal diseases. Ancient doctors believed that Radix Astragali seu Hedysari is excellent in tonifying the middle, supplementing Qi, and dredging through the triple energizer. In modern times, many doctors have found that whether it is used as a single drug or in combination with other drugs, it is widely used in clinical practice and has a good effect in inducing diuresis.

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Rumyantcev, Ernest G., and Evgeniy P. Ronnov. "DETERMINATION OF ELEMENTS AND CHARACTERISTICS OF RIVER SUCTION DREDGERS AT INITIAL DESIGN STAGES." Russian Journal of Water Transport, no. 62 (March 10, 2020): 71–80. http://dx.doi.org/10.37890/jwt.vi62.50.

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The article provides a methodology for calculating the basic elements and characteristics of river dredgers at the stages of research design by means of the statistical method. For the study, the most common projects of river non-self-propelled dredgers with both a residential superstructure and without it, in a wide range of soil productivity, were used. The dependences of the total displacement and the main engine power on such basic technical data as suction dredger performance and loosening depth were analyzed in detail. Graphic dependencies and analytical expressions for determining the main suction dredger dimensions were obtained. The issue of choosing the length of the main dredger compartments is considered, which allows to solve the problem of pre-splitting the hull into compartments. The analysis of the accuracy of the obtained statistical dependencies for determining the length of the vessel is provided.

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Lima, Silvio F. B., Martin L. Christoffersen, José C. N. Barros, and Manuella Folly. "Records and Descriptions of Epitoniidae (Orthogastropoda: Epitonioidea) from the Deep Sea off Northeastern Brazil and a Checklist ofEpitoniumandOpaliafrom the Atlantic Coast of South America." International Journal of Zoology 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/394381.

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A total of six genera and 10 species of marine gastropods belonging to the family Epitoniidae were collected from dredges of the continental slope off Brazil during the development of the REVIZEE (Live Resources of the Economic Exclusive Zone) Program. These species, referable to the generaAlora, Amaea, Cycloscala, Epitonium, Gregorioiscala,andOpalia,are reported from bathyal depths off northeastern Brazil.Alorasp.,Gregorioiscala pimentain. sp., andOpalia revizeen. sp. are species heretofore unknown to science. A list of the species ofEpitoniumandOpaliafrom the Atlantic coast of South America is presented based primarily on data from the literature. In addition, an overview of the biodiversity and distribution of the genera studied is presented for the Atlantic Ocean.

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Roman, Sally A., and David B. Rudders. "Selectivity of Two Commercial Dredges Fished in the Northwest Atlantic Sea Scallop Fishery." Journal of Shellfish Research 38, no. 3 (December 26, 2019): 573. http://dx.doi.org/10.2983/035.038.0308.

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Journal articles on the topic 'Dredges'

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