Sinking Velocity Research Articles

Slowly Sinking Particles Underlie Dissolved Iron Transport Across the Pacific Ocean

AbstractContinental shelf sediments are an important source of iron (Fe) in the oceans. Observational data suggest that basin‐scale transport of sedimentary sourced Fe accompanies the ventilation of the intermediate layer in the North Pacific. Here we use a marine biogeochemical model to explore the Fe transport mechanism with a focus on the role of sinking particles. The lateral penetration of sedimentary sourced Fe was best simulated when we assumed a short desorption and disaggregation length scale of Fe from sinking particles. The simulation results indicated that Fe is laterally transported mainly through interactions with particles with sinking velocities of 180–460 m yr−1; these velocities are two orders of magnitude slower than typical sinking rates of marine aggregates determined from mass flux measurements. Slowly sinking particles drive the basin‐scale transport of Fe by prolonging its residence time and by injecting sedimentary sourced Fe supplied originally to less dense waters into the intermediate layer water across isopycnal surfaces. A large amount of Fe from shelf sediments of the Okhotsk and Bering Seas is exported to the North Pacific through this particle interaction. These results highlight a biogeochemical linkage between the marginal seas and ocean basins that has been overlooked in global ocean models.

Physical properties of extruded fish feed containing silkworm (Bombyx mori) pupae meal

The silkworm pupae (Bombyx mori) may be an interesting resource for aquaculture feed, due to its high nutritional value. The present work evaluates the physical properties of five extruded diets for gilthead seabream (Sparus aurata) containing 0, 2.5, 5, 10 or 15% of non-defatted silkworm pupae meal. The physical properties studied included: expansion ratio, density, hardness, durability, water absorption index, water solubility index, floatability, sinking velocity and fat leakage. Feed formulated with insect meal showed an increase in expansion ratio, hardness and durability, while water absorption index and sinking velocity decreased. The pellets from these diets showed no increased nutrient leaching or fat leakage. Thus, it is possible to include up to 15% of silkworm pupae meal in extruded fish feed without impairing its physical quality.

Sinking microplastics in the water column: simulations in the Mediterranean Sea

Abstract. We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects (inertia, Coriolis force, small-scale turbulence and variable seawater density), and we bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.

Unstable Density‐Driven Convection of CO2 in Homogeneous and Heterogeneous Porous Media With Implications for Deep Saline Aquifers

AbstractDensity‐driven convection mixing has been identified to enhance CO2 trapping in deep saline aquifers storage. In this study, the dynamics of fingering instability and associated mass transfer caused by convection mixing between the movements of miscible analogue fluid pairs are investigated by magnetic resonance imaging (MRI). Two kinds of homogeneous porous media and six kinds of heterogeneous porous media with varying permeability permutations were used at ambient pressure and temperature. In homogeneous porous media, the detail analyses on the data of fingering pattern, finger number and distribution identify that the large finger sizes and high sinking velocities can be developed when the permeability up to 3.3 × 10−11 m2. In heterogeneous porous media, the sand layer first touched by downward fingers plays a dominant role in finger evolution, channeling and fingering convection mechanisms were found among these cases. Moreover, the dissolution rate characterized by Sherwood number (Shm) (enhance or inhibit fluid mixing, depending on the layout of the sand layer) was found to be independent of the local convection dissolution, such as vortex flow and finger splitting at the sand boundary with mutation permeability (enhanced fluid mixing, promoting CO2 dissolution in carbon storage). Finally, the total CO2 dissolution rate Shm in all cases was compared, Shm are at a range of 970–5,079 in homogeneous porous media, while are 190–688 in heterogeneous porous media.

Microplastic changes the sinking and resuspension rates of marine mussel biodeposits

Microplastic (MP; < 5 mm) is ubiquitous in marine environments and is likely transported by biotic benthic-pelagic coupling. Mussels are key benthic-pelagic couplers, concentrating particles from the water column into dense and nutrient rich biodeposits. This study examined how MP affects benthic-pelagic coupling processes of mussels exposed to feeding regimes with and without MP by measuring four attributes of biodeposits: 1) morphology, 2) quantity of algal and MP particles, 3) sinking rate, and 4) resuspension velocity. We found interacting effects of particle treatment and biodeposit type on biodeposit morphology. Biodeposits from the algae treatment contained more algal cells on average than biodeposits from the MP treatment. Biodeposits from the MP treatment sank 34–37% slower and resuspended in 7–22% slower shear velocities than biodeposits from the algae treatment. Decreases in sinking and resuspension velocities of biodeposits containing MP may increase dispersal distances, thus decreasing in-bed nutrient input and increasing nutrient subsidies for other communities.

Growth performance and acoustic feeding behavior of two size classes of Litopenaeus vannamei fed pelleted and extruded diets

This study aimed to compare the growth performance, food consumption, and acoustic feeding behavior of two size classes of Litopenaeus vannamei fed on extruded and pelleted diets. Two similar diets (35% crude protein) prepared by extrusion or pelletizing methods were offered to two shrimp size classes: small (3.83 ± 0.16 g) and large (10.28 ± 0.37 g). Shrimp were reared in 100-L aquaria (salinity 6 ppt, temperature 28 °C); growth performance and survival were analyzed at the end of 4 and 8 weeks for small and large size classes, respectively. Hydrophones recorded the sounds of shrimp feeding activity for 30-min intervals, after food remains were collected to evaluate consumption. Physical (pellet durability index, hardness, water absorption, density, sinking velocity, dry matter retention) and chemical (aromatic amino acids (AAA) leaching) characteristics of the diets were evaluated before and after soaking. Extruded diet presented higher durability and hardness before soaking, but its higher water absorption resulted in markedly texture softened and higher AAA leaching. Both shrimp size classes presented no significant differences in final mean weight, biomass, weight gain, survival, food conversion, and food consumption between pelleted or extruded diets. The mean acoustic energy did not differ between diets, but larger shrimp produced higher energy during feeding activity. The energy showed a significant progressive decrease along time intervals (10, 20, and 30 min) for both size classes and diets. Despite the different characteristics between pelleted and extruded diets, both resulted in similar shrimp performance and acoustic feeding profile activity under laboratory conditions.

Influential Parameter Analyses for Sinking Velocity with Measured Data

To study the effect of operational parameters on the sinking velocity of the landing gear of carrier-based aircraft, the influential analyses of various related parameters were performed based on the measured data of F/A-18. The probabilistic statistical characteristics of the sinking velocity were firstly investigated. And then correlation coefficient method and Levenberg-Marquardt (LM) algorithm were applied to finish influential parameter analyses. The analysis results show that the important influential parameters are aircraft glide angle, deck pitch angle, approaching velocity and engaging velocity; the mathematical model of sinking velocity is established by LM algorithm, and the determination coefficient is calculated via the variance analysis, which reveals that the proposed regression model is good. Compared with the measured data, the average errors for the predicted values of the established model of sinking velocity are less than 5%, which validates the effectiveness and feasibility of the method in engineering practice. The present efforts provide a way to study the relationships of the sinking velocity and the related influential parameters. And this work was proved to be a useful method for the study of sinking velocity.

Optimization of Some Physical and Functional Properties of Extruded Soybean Crud Residue-base Floating Fish Feed

Effect of some extrusion factors on soybean crud residue-based floating fish feed was investigated. Extrusion was conducted at 20%, 25% and 30% moisture content level, die size of 2 mm, 4 mm and 6 mm and screw speed of 150 rpm, 200 rpm and 250 rpm. Pearson square method of fish feed formulation was used to attain a 35% protein content of catfish feed protein requirement. Optimized value of extrusion factors moisture content, die size and screw speed were 30%, 6 mm and 150 rpm respectively and optimized result of responses, expansion rate (ER) floatation rate (FR) sinking velocity (SV) specific mechanical energy (SME) swelling capacity (SC) water absorption index (WAI) water solubility index (WSI) hydration capacity (HC) and hydration index (HI) are 32.73%, 95.87%, 0.024 ms^-1, 16.97 KJ/kg, 1.73, 1.61, 2.76, 0.51, and 0.67 respectively. Feed moisture content and die size have the most significant effect on the physical and functional properties of extrudate. Coefficient of determination R² ranges from 0.65 to 0.96, lack of fit not-significant, desirability in optimization of 0.806, suggesting adequacy of research. Soybean crud residue base floating fish feed has been formed and evaluated with an outcome of high efficacy. This extruded produce can be used for both domestic and industrial scale of catfish feed production.

Modeling polymer crystallisation induced by a moving heat sink.

Recent experimental work has shown that polymer crystallisation can be used to "move" and organize nanoparticles (NP). As a first effort at modeling this situation, we consider the classical Stefan problem but with the modification that polymer crystallisation does not occur at a single temperature. Rather, the rate of crystallisation is proportional to its subcooling, and here we employ a form inspired by the classical Avrami model to describe this functional form. Our results for the movement of the polymer crystallisation front, as defined as the point where the crystallinity is 50%, closely track the results of the classical Stefan problem. Thus, at this level of approximation, the crystallisation kinetics of the polymer do not cause qualitative changes to the physics of this situation. Inspired by this fact we study the more interesting situation where the directional recrystallisation of a polymer melt is considered, e.g., through the application of a moving heat sink over an initially molten polymer, reminiscent of a processing technique termed zone annealing. The polymer crystallisation shows that a steady state exists for a range of sink velocities. The solid-melt interface moves slightly ahead of the sink but at the same velocity. The steady-state distance between the sink and the interface decreases with increasing sink velocity - this is a consequence of the excess cooling provided by the sink over what is required to crystallise the melt. The most interesting new result is that the temperature of the crystal-melt interface decreases with increasing sink velocity. This is in line with the ansatz of Lovinger and Gryte who suggested that larger zone annealing velocities correspond to progressively larger effective undercoolings at which polymer crystallisation occurs.

Effect of the inclusion of microalgae on the physical properties of extruded feed for gilthead seabream (Sparus aurata L.)

The inclusion of new ingredients in fish feed can affect the physical quality of the pellets. In order to study the effect of the addition of microalgae on the physical properties of the pellets, 15 extruded diets were studied that included three different species of microalgae (Nannochloropsis gaditana, Tetraselmis chuii and Chlorella vulgaris) at five different inclusion levels (0, 2.5, 5, 10 and 15%). The feed mixtures were extruded using a single-screw extruder (barrel temperature profile: 90–95–100 °C; die temperature: 105 °C; screw speed: 40–50 rpm). The physical properties studied included: expansion ratio, density, hardness, pellet durability index, water absorption index, water solubility index, floatability, sinking velocity, fat leakage and starch gelatinization. The present study showed that the physical properties of the pellets are influenced by the type and amount of microalgae used. The physical quality of the feed was modified, generally increasing its hardness and durability and reducing the fat leakage.

Dynamics Test Research of Bounce of Carrier-Based Aircraft Arresting Hook

The test of arresting hook bounce is one of the most essential technologies in the design and research of arresting hook. In order to research the dynamic performance of the hook after touchdown and impacting with the deck when the aircraft is arrested, an approach for a certain type of aircraft arresting hook bounce test is proposed in this paper. Solutions to critical technique issues arising in the test process such as aircraft sinking velocity control, aircraft horizontal velocity simulation, and simulation of the performance of the damper are derived and verified by the bounce test of the arresting hook. The bounce height, bounce distance, stroke length of the arresting hook damper after the hook is impacted are measured by the test. The test method proposed can be used for researching the bounce of arresting hook and providing reliable test data for the design of carrier-based aircraft and arresting hook.

Different starch sources affect physical characteristics of extruded feeds prepared for the Malaysian mahseer, Tor tambroides

ABSTRACT Starches from three local crops (sago, Metroxylon sagu; cassava, Manihot esculenta; and taro, Colocasia esculenta) were tested as replacements for corn starch in the production of extruded feed for the Malaysian mahseer, Tor tambroides . Four test feeds were formulated to contain 40.00% protein and 23.44% starch, and extruded using a single-screw extruder (120 rpm speed, 2 mm diameter die head). Temperatures at the feeding, mixing, compressing, and die zones were set at 60°C, 100°C, 120°C, and 160°C, respectively. Physical properties used to evaluate the quality of the extrudates were expansion ratio, bulk density, true density, pellet durability index, water stability, floatability index, sinking velocity, and sample microstructure. Results showed that test starches produced extrudates with fairly equal quality to corn starch extrudates for expansion ratio, pellet durability index, pellet durability index, and floatability index. Cassava starch extrudates had the best external appearance observed under electron microscopy. This study shows the potential that these three starches have in aquafeed production especially in producing quality Malaysian mahseer feed.

Size does not matter after all: No evidence for a size-sinking relationship for marine snow

The biological carbon pump is a critical component for uptake of carbon by the oceans. Most of this is mediated by gravitational sinking of particles and it is generally assumed that there is a positive relationship between sinking velocities and sizes of particles. Due to the difficulties inherent in measuring the sinking velocity of untouched and undamaged particles, the majority of studies have been based on artificial solid particles or laboratory generated marine snow formed from homogenous material, e.g. phytoplankton cultures. Here, we present results from a newly developed optical method that measures sizes and sinking velocities of undisturbed in situ aggregates in the mesopelagic zone. The measurements were done at depths between 90 and 530 m throughout day and night. In total we measured 55 image sequences of aggregate sizes and sinking velocities, resulting in measurements of 1060 individual aggregates. Only 10 sequences showed significant correlations between aggregate size and sinking velocity. Furthermore, only 8 of the 10 significant correlations between size and settling were positive. Despite similar optical appearance, similar sized aggregates had different sinking velocities, suggesting that aggregates formed in situ are heterogeneous with different compositions, structure and densities. This complicates estimates of sinking velocity from aggregate size only and one has to be careful when estimating downward particle flux based on in situ size-distribution and abundance of aggregates and theoretical relationships between size and sinking velocity. Hence, this study forces the conclusion that estimates of downward particle flux which use particle size distributions must also include information about aggregate composition, compactness and density from in situ optics or direct particle and aggregate sampling.

Plankton Tracker: A novel integrated system to investigate the dynamic sinking behavior in phytoplankton

Phytoplankton sinking is an important property that can determine community composition, affecting nutrient and light absorption in the photic zone, and influencing biogeochemical cycling via material loss to the deep ocean. To date, the difficulty in exploring the sinking processes is partly due to methodological limitations in measuring phytoplankton sinking rate. However, in the last decade, works have illustrated various methods based on some non-invasive and low perturbing approaches (laser scanner, video-microscopy, fluorescence spectroscopy). In this study, we review the methods for sinking rate estimation and describe the Plankton Tracker, a novel integrated system to investigate in vivo the dynamic sinking behavior of phytoplankton. Plankton Tracker is composed of a long-distance objective and a video-microscopy facility coupled with a specifically developed image analysis system (Plankton Tracker Elements). Diatoms and dinoflagellates were individually-tracked. By processing recorded videos and images, sinking traits (e.g. trajectory length and complexity, sinking velocity, turning angle) were obtained simultaneously with morphological traits (e.g. linear dimensions). We also applied a Biased Correlated Random Walk model to sinking traits. Particularly, we found linear motion in the colony-forming Thalassiosira sp. and sinusoidal reorientation in the dinoflagellate Scrippsiella acuminata. We found complex suspension dynamic of the large Coscinodiscus sp. In this view, the Plankton Tracker approach is likely to provide more insights towards the exploration of dynamic sinking behavior in phytoplankton.

Determination of Some Engineering Properties of Floatable Fish Feed Obtained from Different Companies

This research work presents useful information about different floatable fish feeds obtained from different companies, which serves as database for people work intensively in fish farming and help them in solving many problems associated with the feeding effectiveness and feed handling. The main objective of this project is to study some physical and mechanical properties of fish feed pellets of different sizes. These properties included; Density, Moisture content, Surface area, Floatability, Sizes, Sinking velocity, Expansion ratio, Repose angle. The actual sizes of the extruded fish feed used ranged from 3 mm to 9 mm, However, Company 1 did not have 9 mm for producing that size of the pellet. The floatability ranged from 79.51 to 98.00%, the density ranged from 0.03 to 0.08 g/cm3, the moisture content ranged from 8.94 to 29.26%, the expansion ratio ranged from 1.02 to 1.54%, the sinking velocity ranged from 0.008 to 0.1 m/s2, the repose angle ranged from 27 to 38° while the colour of the feed ranged from light to dark brown according to Tables 1, 2 and 3 respectively. The results obtained from the experiment were subjected to ANOVA test using SPSS (Special Packages for Social Science) package. The physical and Mechanical properties of the floatable fish feed obtained from these three companies were significantly different from one another.

Resolution dependency of sinking Lagrangian particles in ocean general circulation models.

Any type of non-buoyant material in the ocean is transported horizontally by currents during its sinking journey. This lateral transport can be far from negligible for small sinking velocities. To estimate its magnitude and direction, the material is often modelled as a set of Lagrangian particles advected by current velocities that are obtained from Ocean General Circulation Models (OGCMs). State-of-the-art OGCMs are strongly eddying, similar to the real ocean, providing results with a spatial resolution on the order of 10 km on a daily frequency. While the importance of eddies in OGCMs is well-appreciated in the physical oceanographic community, other marine research communities may not. Further, many long term climate modelling simulations (e.g. in paleoclimate) rely on lower spatial resolution models that do not capture mesoscale features. To demonstrate how much the absence of mesoscale features in low-resolution models influences the Lagrangian particle transport, we simulate the transport of sinking Lagrangian particles using low- and high-resolution global OGCMs, and assess the lateral transport differences resulting from the difference in spatial and temporal model resolution. We find major differences between the transport in the non-eddying OGCM and in the eddying OGCM. Addition of stochastic noise to the particle trajectories in the non-eddying OGCM parameterises the effect of eddies well in some cases (e.g. in the North Pacific gyre). The effect of a coarser temporal resolution (once every 5 days versus monthly) is smaller compared to a coarser spatial resolution (0.1° versus 1° horizontally). We recommend to use sinking Lagrangian particles, representing e.g. marine snow, microplankton or sinking plastic, only with velocity fields from eddying Eulerian OGCMs, requiring high-resolution models in e.g. paleoceanographic studies. To increase the accessibility of our particle trace simulations, we launch planktondrift.science.uu.nl, an online tool to reconstruct the surface origin of sedimentary particles in a specific location.

Efficacy of various coated materials to prevent nutrient leaching for Pacific white shrimp Litopenaeus vannamei commercial diets

AbstractThe physical characteristics and leaching rates of water‐soluble compounds from shrimp feeds are major considerations in nutrient delivery. Yet, there is limited information on nutrient leaching from feeds or the mechanisms to minimize leaching. This study evaluated the efficacy of various coating agents on the physical characteristics and leaching of nutrients from commercial feeds for Litopenaeus vannamei. A series of diets were top coated with two lipid sources (fish or stearin oil) and two additives to the oil (5% wax or gelatin) at three levels (0, 1.5, and 3%). Physical characteristics and leaching of water‐soluble compounds were then characterized. The reduction of leaching was seen with the diets that were top coated with 1.5 or 3% oil, which significantly decreased the leaching of phenylalanine (Phe) after 30 min and 60 min of immersion. Adding 1.5 and 3% oil coating significantly decreased the pellet durability index. Adding gelatin as an additive to the oil significantly slowed sinking velocity and improved water stability and the pellet durability index of the diets. In all, results demonstrated that coating 1.5 or 3% fish or stearin oil decreases the leaching rate. Supplementing 5% gelatin in the coating material for diets can improve the performance of the diets.

An Analysis Scheme of Balancing Energy Consumption with Mobile Velocity Control Strategy for Wireless Rechargeable Sensor Networks.

Wireless Rechargeable Sensor Networks (WRSN) are not yet fully functional and robust due to the fact that their setting parameters assume fixed control velocity and location. This study proposes a novel scheme of the WRSN with mobile sink (MS) velocity control strategies for charging nodes and collecting its data in WRSN. Strip space of the deployed network area is divided into sub-locations for variant corresponding velocities based on nodes energy expenditure demands. The points of consumed energy bottleneck nodes in sub-locations are determined based on gathering data of residual energy and expenditure of nodes. A minimum reliable energy balanced spanning tree is constructed based on data collection to optimize the data transmission paths, balance energy consumption, and reduce data loss during transmission. Experimental results are compared with the other methods in the literature that show that the proposed scheme offers a more effective alternative in reducing the network packet loss rate, balancing the nodes’ energy consumption, and charging capacity of the nodes than the competitors.

Full-fat black soldier fly larvae (Hermetia illucens) meal and paste in extruded diets for Atlantic salmon (Salmo salar): Effect on physical pellet quality, nutrient digestibility, nutrient utilization and growth performances

The present study investigated the effect of graded levels of black soldier fly larvae (BSFL) (Hermetia illucens) meal and paste on physical pellet quality, digestibility and utilization of nutrients and growth performances in extruded diets for Atlantic salmon (Salmo salar). A total of 1260 Atlantic salmon with 34 g of mean initial weight were randomly distributed into 21 fiberglass tanks and fed with one of seven isonitrogenous, isolipidic and isoenergetic diets for seven weeks. The experimental diets consisted of a control diet based on fishmeal, soy protein concentrate, corn gluten, faba bean and fish oil (Control-1); three diets with increased levels of full-fat BSFL meal, substituting 6.25% (6.25IM), 12.5% (12.5IM) and 25% (25IM) of the protein content of Control-1; two diets with increased levels of full-fat BSFL paste, substituting 3.7% (3.7IP) and 6.7% (6.7IP) of protein from Control-1 and an extra control diet with 0.88% of formic acid (Control-2). Pellet durability and hardness were overall high for all diets. However, the expansion, sinking velocity and water stability of feed pellets were lower with increased inclusion of BSFL meal and paste. Dietary inclusion of BSFL meal or paste did not affect the feed intake of fish. Further, replacing the protein content of the control diet with up to 12.5% and 6.7% of BSFL meal and paste, respectively, did not compromise fish growth rate or feed conversion ratio, although polynomial contrast analysis showed that increasing BSFL meal level in the diet linearly (p < .05) decreased these parameters. However, apparent digestibility coefficient (ADC) of protein and lipid, protein efficiency ratio and lipid retention were reduced linearly (p < .05) with increasing inclusion level of BSFL meal. Further, increasing dietary levels of BSFL paste linearly (p < .05) reduced ADC of protein, protein efficiency ratio and phosphorous retention. Despite the decreased ADC of protein, protein retention was not compromised by the inclusion of BSFL meal or paste. Replacement of 25% of dietary protein with BSFL meal decreased (p < .05) growth rate, accompanied by lower (p < .05) ADC and utilization of lipids and protein efficiency ratio. The present study showed that BSFL meal and paste could replace up to 12.5% and 6.7% of dietary protein, respectively, without compromising growth performance in Atlantic salmon.

The Interpretation of Particle Size, Shape, and Carbon Flux of Marine Particle Images Is Strongly Affected by the Choice of Particle Detection Algorithm

In situ imaging of particles in the ocean are rapidly establishing themselves as powerful tools to investigate the ocean carbon cycle, including the role of sinking particles for carbon sequestration via the biological carbon pump. A big challenge when analysing particles in camera images is determining the size of the particle, which is required to calculate carbon content, sinking velocity and flux. A key image processing decision is the algorithm used to decide which part of the image forms the particle and which is the background. However, this critical analysis step is often unmentioned and its effect rarely explored. Here we show that final flux estimates can easily vary by an order of magnitude when selecting different algorithms for a single dataset. We applied a range of static threshold values and 11 different algorithms (7 threshold and 4 edge detection algorithms) to particle profiles collected by the LISST-Holo system in two contrasting environments. Our results demonstrate that the particle detection method does not only affect estimated particle size but also particle shape. Uncertainties are likely exacerbated when different particle detection methods are mixed, e.g., when datasets from different studies or devices are merged. We conclude that there is a clear need for more transparent method descriptions and justification for particle detection algorithms, as well as for a calibration standard that allows intercomparison between different devices.