scholarly journals Optimising mesh size with escape gaps in a dual-species portunid-trap fishery

2020 ◽  
Vol 5 (6) ◽  
pp. 308-316 ◽  
Author(s):  
Matt K. Broadhurst ◽  
Daniel J. Tolhurst ◽  
Brian Hughes ◽  
Vincent Raoult ◽  
Timothy M. Smith ◽  
...  
Keyword(s):  
Mesh Size ◽  
Trap Fishery

scholarly journals Effects of Mesh Size and Escape Gaps on Discarding in an Australian Giant Mud Crab (Scylla serrata) Trap Fishery

PLoS ONE ◽  
2014 ◽  
Vol 9 (9) ◽  
pp. e106414 ◽  
Author(s):  
Matt K. Broadhurst ◽  
Paul A. Butcher ◽  
Brian R. Cullis
Keyword(s):  
Mesh Size ◽  
Scylla Serrata ◽  
Mud Crab ◽  
Trap Fishery

Escape panels to reduce by-catch in the New South Wales demersal trap fishery

2002 ◽  
Vol 53 (8) ◽  
pp. 1179 ◽  
Author(s):  
John Stewart ◽  
Douglas J. Ferrell
Keyword(s):  
New South ◽  
New South Wales ◽  
Body Height ◽  
Mesh Size ◽  
Wire Mesh ◽  
Turn On ◽  
South Wales ◽  
Fish Traps ◽  
Trap Fishery ◽  
By Catch

Various sizes of wire mesh were tested as escape panels in fish traps in the New South Wales demersal trap fishery. The mesh selectivities of these escape panels were estimated using a 'parlour' trap, which is analogous to the 'covered codend' designs used to test selectivity in trawls. The results showed that we could estimate the selection size (l50) for most species based on their maximum body height and the maximum aperture of the escape panel mesh. This enabled us to make escape panel mesh that selected the main species in the fishery, snapper (Pagrus auratus), at a predetermined size. Placing the escape panel meshes with the longest axis orientated either vertically or horizontally showed that fish behaviour is important in determining mesh size selectivity. However, the selection size of some species was unaffected by the orientation of the mesh, suggesting that they were able to turn on their sides to escape. Silver trevally (Pseudocaranx dentex) formed tight schools within traps and were selected at smaller sizes when the meshes were oriented with the longest axis horizontally, suggesting that they do not turn on their sides to escape. Selectivity ogives were used with estimates of the sizes of retained and discarded fish captured in the fishery to estimate the impacts of using the escape panels tested on current landings. The results show the difficulty in designing effective escape panels in a multispecies fishery.

THE COMPOSITION AND DISTRIBUTION OF BENTHIC FORAMINIFERA AT CORAL REEF ECOSYSTEM IN THOUSANDS ISLAND

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Lumban Nauli Lumban Toruan ◽  
Dedi Soedharma ◽  
Kresna Tri Dewi
Keyword(s):  
Coral Reef ◽  
Human Activities ◽  
Close Association ◽  
Mesh Size ◽  
Coral Reef Ecosystem ◽  
Composition Distribution ◽  
Benthic Foraminifers ◽  
High Nutrient ◽  
Binocular Microscope ◽  
Reef Ecosystem

Composition and distribution of foraminifers are affected by human activities and have close association with coral reef ecosystem. The aims of this research were to investigate the benthic foraminifers’ composition and distribution in sediment of coral reef ecosystem. Eleven stations of Karang Bongkok, Pramuka, and Onrust Island were observed in this study. The sediments were taken from surface substrate up to 2 cm under the substrate. Samples were washed on sieve with mesh size 0,063 mm, and then dried in oven with 50°C of temperature  for two hours. After separating from the sediment, the foraminifers were laid on foraminiferal slide and indentified using binocular microscope. The highest composition of symbiont-bearing foraminiferal assemblages which associated with reef ecosystem was in East Pramuka (78.17%) and the lowest was in South Onrust (21,83%). The opportunistic type had the highest composition in South Onrust (38.67%) and the lowest was in South Karang Bongkok. In west Pramuka had the highest composition of heterotrophic type (57.17%) and the lowest was in North Onrust (11.33%). Onrust Island was dominated by opportunistic type, indicating high nutrient. The highest amount of foraminifers’ taxa was found in Karang Bongkok with good coral reef coverage, while the lowest in Onrust facing with Jakarta Bay. Keywords: composition, distribution, benthic foraminifers, coral reef.

WALLEX Nos. 55 and 505

Alloy Digest ◽  
1995 ◽  
Vol 44 (8) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Mesh Size ◽  
Powder Metal ◽  
Application Methods

Abstract Wallex Nos. 55 and 505 are similar composite hardfacing powders with different mesh size for different application methods. The minimum hardness is RC 58. This datasheet provides information on composition, physical properties, and hardness. It also includes information on corrosion resistance as well as powder metal forms. Filing Code: CO-98. Producer or source: Wall Colmonoy Corporation.

scholarly journals Influence of finite element mesh size on the carrying capacity analysis of single-row ball slewing bearing

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110090
Author(s):  
Peiyu He ◽  
Qinrong Qian ◽  
Yun Wang ◽  
Hong Liu ◽  
Erkuo Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Carrying Capacity ◽  
Mesh Size ◽  
Finite Element Mesh ◽  
Fe Model ◽  
Element Mesh ◽  
Heavy Load ◽  
Slewing Bearing ◽  
Maximum Contact ◽  
Slewing Bearings

Slewing bearings are widely used in industry to provide rotary support and carry heavy load. The load-carrying capacity is one of the most important features of a slewing bearing, and needs to be calculated cautiously. This paper investigates the effect of mesh size on the finite element (FE) analysis of the carrying capacity of slewing bearings. A local finite element contact model of the slewing bearing is firstly established, and verified using Hertz contact theory. The optimal mesh size of finite element model under specified loads is determined by analyzing the maximum contact stress and the contact area. The overall FE model of the slewing bearing is established and strain tests were performed to verify the FE results. The effect of mesh size on the carrying capacity of the slewing bearing is investigated by analyzing the maximum contact load, deformation, and load distribution. This study of finite element mesh size verification provides an important guidance for the accuracy and efficiency of carrying capacity of slewing bearings.

scholarly journals Augmented Lagrangian preconditioners for the Oseen–Frank model of nematic and cholesteric liquid crystals

2021 ◽  
Author(s):  
Jingmin Xia ◽  
Patrick E. Farrell ◽  
Florian Wechsung
Keyword(s):  
Liquid Crystals ◽  
Augmented Lagrangian ◽  
Augmented Lagrangian Method ◽  
Mass Matrix ◽  
Unit Length ◽  
Mesh Size ◽  
Schur Complement ◽  
Cholesteric Liquid Crystals ◽  
Multigrid Algorithm ◽  
The Cost

AbstractWe propose a robust and efficient augmented Lagrangian-type preconditioner for solving linearizations of the Oseen–Frank model arising in nematic and cholesteric liquid crystals. By applying the augmented Lagrangian method, the Schur complement of the director block can be better approximated by the weighted mass matrix of the Lagrange multiplier, at the cost of making the augmented director block harder to solve. In order to solve the augmented director block, we develop a robust multigrid algorithm which includes an additive Schwarz relaxation that captures a pointwise version of the kernel of the semi-definite term. Furthermore, we prove that the augmented Lagrangian term improves the discrete enforcement of the unit-length constraint. Numerical experiments verify the efficiency of the algorithm and its robustness with respect to problem-related parameters (Frank constants and cholesteric pitch) and the mesh size.

scholarly journals Spatial and temporal resolution of a fast-response aerodynamic pressure probe in grid-generated turbulence

2021 ◽  
Vol 62 (2) ◽  
Author(s):  
Florian M. Heckmeier ◽  
Stefan Hayböck ◽  
Christian Breitsamter
Keyword(s):  
Temporal Resolution ◽  
Pressure Sensors ◽  
Mesh Size ◽  
Reynolds Numbers ◽  
Fast Response ◽  
Pressure Probe ◽  
Aerodynamic Pressure ◽  
Kolmogorov Length Scale ◽  
High Bandwidth ◽  
Velocity Spectra

Abstract The spatial and temporal resolution of a fast-response aerodynamic pressure probe (FRAP) is investigated in a benchmark flow of grid-generated turbulence. A grid with a mesh size of $$M=6.4$$ M = 6.4 mm is tested for two different free-stream velocities, hence, resulting in Reynolds numbers of $$Re_M= \{4300,12800\}$$ R e M = { 4300 , 12800 } . A thorough analysis of the applicability of the underlying assumptions with regard to turbulence isotropy and homogeneity is carried out. Taylor’s frozen turbulence hypothesis is assumed for the calculation of deducible flow quantities, like the turbulent kinetic energy or the dissipation rate. Furthermore, besides the examination of statistical quantities, velocity spectra of measurements downstream of the grid are quantified. Results of a small fast-response five-hole pressure probe equipped with piezo-resistive differential pressure sensors are compared to single-wire hot-wire constant temperature anemometry data for two different wire lengths. Estimates of temporal and spatial turbulent scales (e.g., Taylor micro scale and Kolmogorov length scale) show good agreement to data in the literature but are affected by filtering effects. Especially in the energy spectra, very high bandwidth content cannot be resolved by the FRAP, which is mainly due to bandwidth limits in the temporal calibration of the FRAP and the minimal resolution of the integrated sensors. Graphic abstract

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