Bottom Vessels Research Articles

The Fishing Ground of Bottom Longline Vessels and Exploitation Rate of Tiger Grouper (<i>Epinephelus aerolatus</i>) in Arafura Waters

As excessive capture activity adversely impacts fisheries sector, fish resources management is a necessity. This study was conducted as a scientific contribution for the managements of bottom longline fisheries in Arafura Waters and areolate grouper (Epinephelus areolatus) as one of the target catches. It was carried out from February to December 2017 and in November 2018. Data on the fishing grounds of eight bottom longline vessels were obtained from the vessel monitoring system (VMS) of Probolinggo Marine and Fisheries Resources Supervisory Unit, Mayangan Probolinggo Fishing Port, and Marine and Fisheries Resources Surveillance (PSDKP) Tual Station. Based on the analysis of the coordinates from the VMS, the fishing grounds of the bottom longline vessels in Arafura waters were found around Dolak until the border with Merauke and around Timika until Aru Islands. The composition of dominant catches consisted of croaker (Pennahia spp.) and snapper (Lutjanus spp.), as well as grouper (Epinephelus spp.) in a smaller proportion. The size structure of the areolate grouper caught with bottom longlines was 21.5–54.5 cmTL; its length at first capture (Lc) was 33.9 cmTL; and its asymptotic length was 70.5 cmTL. Its growth rate (K) was found 0.26 per year. The fishing mortality (F) of the species was found higher than its natural mortality (M), and its exploitation level (E) was 0.74, meaning that the species was already overfished. The exploitation should be reduced by 40–50% to keep the fish resources in Arafura sustainable, especially for areolate grouper. Keywords: fishing ground, bottom longline, exploitation level, tiger grouper, Arafura

Local Turbulent Energy Dissipation Rate in an Agitated Vessel: Experimental and Turbulence Scaling

The hydrodynamics and the flow field in an agitated vessel were measured using 2-D time resolved particle image velocimetry (2-D TR PIV). The experiments were carried out in fully baffled cylindrical flat bottom vessels 300 and 400 mm in inner diameter. The 300 mm inner diameter tank was agitated by a Rushton turbine 100 mm in diameter, and the 400 mm inner diameter tank was agitated by a Rushton turbine 133 mm in diameter. Three liquids of different viscosities were used as the agitated liquid: (i) distilled water (ν = 9.35 × 10–7 m2/s), (ii) a 28 vol % aqueous solution of glycol (ν = 2 × 10–6 m2/s), and (iii) a 43 vol % aqueous solution of glycol (ν = 3 × 10–6 m2/s). The velocity fields were measured at an impeller rotation speed in the range from 300 to 850 rpm, which covers the Reynolds number range from 50000 to 189000. This means that fullydeveloped turbulent flow was reached. The experiments were performed to investigate the applicability of the following relations: e* = e/(u4/ν) = const, vK/u = const, Λ/ηK = const, τΛ/τK = const, e* = e/((Nd)4/ν) = const, Λ/d ∝ Re–1, ηK/d ∝ Re–1, vK/(Nd) = const, NτΛ ∝ R–1, NτK ∝ Re–1, and e/(Nq) ∝ Re. These formulas were theoretically derived in our previous work, using turbulence theory, in particular, using turbulence spectrum analysis. The correctness of the proposed relations is investigated by statistical hypothesis testing.

Effect of enrichment time and dietary DHA and non-highly unsaturated fatty acid composition on the efficiency of DHA enrichment in phospholipid of rotifer (Brachionus Cayman)

Abstract An increasing number of studies suggest that DHA associated with dietary phospholipid (PL) is better metabolically available for fish larvae. Knowledge on how to increase DHA levels in the major PL classes of the live feed is needed. Brachionus Cayman was cultured in conical fibreglass vessels, enriched with commonly used commercial diet Multigain or DHA Selco (DSelco) in flat bottom vessels at 20 °C. The changes of DHA content in the PL of the rotifers through enrichment and through a starvation phase post-enrichment were investigated in order to define an appropriate enrichment time and to test the stability of DHA post-enrichment. The different dietary non-HUFA (non-highly unsaturated fatty acid) composition of DSelco (25.1% SFA, 32.1% MUFA) and Multigain (40.7% SFA, 2.11% MUFA) allowed an evaluation on how SFA and MUFA might affect the efficiency of DHA enrichment of phospholipid in the rotifers. Rotifer samples were collected at 0 h, 1 h, 2 h, 4 h, 8 h, 12 h and 24 h after initiation of enrichment. Total lipid (TL) and the fatty acid composition in TL, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of rotifers and enrichment diets were analysed. The highest DHA levels in PC (23.0%) and PE (16.5%) in Cayman were found after 24 h enrichment with Multigain, and levels were far higher than obtained earlier. The enriched DHA was stable at 10 °C for at least 24 h post-enrichment under starving conditions ( p > 0.05), whereas a significant ( p Statement of relevance The paper is bringing information about fatty acid enrichment of rotifers in questions that are so far quite unclear and could have a strong impact on larviculture of marine fish larvae. This study shows methods to obtain high level of DHA in phospholipids of rotifer. The results could potentially have a significant impact to improve current fatty acid enrichment protocols for rotifers.

Process Synthesis of Batch Distillation Systems

A novel synthesis framework is presented for evaluating different configurations and sequences of batch distillation processes and identifying the most appropriate flowsheet and cost-effective operating conditions simultaneously. A superstructure for batch distillation systems is constructed by employing a generic unit, which consists of segments of trays with top and bottom vessels attached to it, and accommodating three different types of integrated network design options for feed connections, sequencing connections, and configuration connections. This systematic formulation of batch distillation sequencing design problems allows not only the optimization of conventional flowsheets, but also the generation of novel configurations and sequences. The optimization framework is based on an mixed-integer nonlinear programming (MINLP) problem, which is effectively solved with a hybrid optimization method using simulated annealing and sequential quadratic programming (SA-SQP). Case studies are presented to demonstrate how the proposed approach can be applied in practice to improve cost-effectiveness of batch distillation systems.

Regional differences in endothelial function in horse lungs: possible role in blood flow distribution?

We investigated regional differences of in vitro responses of pulmonary arteries (6-mm OD) from the dorsocaudal (top) and cranioventral (bottom) lung regions to endothelium-dependent vasodilators (methacholine, bradykinin, and calcium ionophore A-23187). Methacholine relaxed endothelium-intact top vessels; however, in bottom vessels, a small relaxation preceded a profound contraction. In top vessels, removal of endothelial cells converted relaxation to contraction, and in bottom vessels it abolished relaxation and enhanced contraction. Bradykinin and A-23187 were more potent and caused greater endothelium-mediated relaxation in top than in bottom arteries. The endothelium-independent vasodilator sodium nitroprusside caused similar relaxations in all rings. Nomega-nitro-L-arginine and NG-monomethyl-L-arginine and methylene blue abolished relaxation of top and bottom arteries to methacholine; meclofenamate had little effect. We conclude that regional differences in endothelium-mediated relaxation are caused by differences in the magnitude of the endothelial release of nitric oxide. Similar differences in endothelium-dependent flow-mediated vasodilation and endothelial nitric oxide release may result in preferential perfusion of caudodorsal lung regions.

Crystal size distribution of aluminum potassium sulfate in a profiled, a dished, or a flat bottom crystallizer equipped with a pitched paddle

Effect of bottom shapes of vessels on crystal size distribution was investigated using a flat, a dished and a profiled bottom vessels for seeded batch crystallization of aluminum potassium sulfate. Two evident crystal size subdistributions (two maxima) were obtained for the flat and dished bottom vessels whereas only a single maximum was observed and the fraction of small crystals became larger than the other two types of vessels in the case of the vessel with a profiled bottom. The flow pattern and the particle motion in vessels with three different bottom shapes were measured in detail prior to the experiment. The results demonstrate that agglomeration of particles due to the induced circulation at the bottom of vessels with flat and dished shapes is the cause for the presence of two maxima.

Can Changing Cod End Mesh Size and Mesh Shape Affect the Nearshore Trawl Fishery off the West Coast of the United States?

Abstract A study, spanning the years 1988–1990, on the impact of trawl cod end mesh size and mesh shape was undertaken onboard nearshore bottom trawl vessels operating under production conditions off the west coast of the United States. Short-term impacts with experimental cod ends were analyzed. Six cod ends were used as treatments: 76-, 114-, 127-, and 140-mm diamond mesh, and 114- and 127-mm square mesh. Three response variables were used to compare these cod ends: utilized catch weight (weight of marketable-sized fish), size-discard catch weight (weight of fish discarded due to small size), and giller weight (weight of fish wedged between meshes). Species composition differed between the “inner nearshore” area (0–91 m depth) and the “outer nearshore” area (>91–183 m depth). For all cod ends, the inner nearshore had a consistently greater percent total discard than the outer nearshore. The individual cod end results showed that the 76-mm diamond gave excessively high size-discard rates for both areas. ...

Regional differences in pulmonary artery endothelial function: a role in the site of EIPH?

SummaryExercise induced pulmonary haemorrhage (EIPH) is thought to result from capillary stress failure associated with high pulmonary vascular pressures during heavy exercise. One possible mechanism for the caudodorsal distribution of haemorrhage is preferential distribution of blood flow to affected regions due to regional differences in pulmonary vascular regulation. Endothelial cells (EC) are known controllers of vascular smooth muscle tone and could play a role in regional distribution of blood flow. The present study investigated relaxation responses to the endothelium‐dependent and independent vasodilators, methacholine (MCh) and nitroglycerin (NTG) in pulmonary arteries from the caudodorsal (top) and cranioventral (bottom) regions of the lung. Pulmonary arteries (7 mm diameter) from 6 horses were isolated from top and bottom regions of the lung and vessels with and without endothelium were mounted in 15 ml tissue baths. Vessels were pre‐contracted with norepinephrine (10−6 M) and changes in isometric tension in response to MCh (10−6 M) and NTG (10−6 M) were compared. MCh consistently relaxed, and never contracted, endothelium‐intact top vessels. In top vessels, relaxation was abolished by removal of EC, suggesting an obligatory role of EC in MCh relaxation. However, in bottom vessels, a small transient relaxation was followed by a profound contraction, enhanced by EC removal. Relaxation to NTG was similar in all vessels. Therefore, in response to MCh, top vessels relax in an endothelium‐dependent manner, while bottom vessels contract. Similar regional differences in endothelium dependent flow mediated vasodilation may result in higher blood flow to the caudodorsal regions of the lung and hence be responsible in part for the location of EIPH.

Provozní zkoušky jednofázové výroby piva v prototypových cylindrokónických tancích.

Provozní zkoušky jednofázové výroby piva v prototypových cylindrokónických tancích.