Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Sinking speed.
Статті в журналах з теми "Sinking speed"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Sinking speed".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
TUCKER, VANCE A. "Gliding Birds: Descending Flight of the Whitebacked Vulture, Gyps Africanus." Journal of Experimental Biology 140, no. 1 (November 1, 1988): 325–44. http://dx.doi.org/10.1242/jeb.140.1.325.
Повний текст джерелаАнотація:
The air speeds and sinking speeds of birds gliding at equilibrium fall in a performance area when these quantities are plotted against one another. Three curves bound the performance area: (i) a curve for minimum sinking speed at each air speed, (ii) a curve for maximum sinking speed at each air speed, and (iii) a curve dependent on the maximum lift coefficient of the wings. I have discussed curve i in a previous paper. This paper discusses the theory of curves ii and iii, which describe rapid descent in gliding birds. I used an optical tracking device (an ornithodolite) to measure air speeds and sinking speeds of 16 African white-backed vultures (Gyps africanus Salvadori) descending rapidly from altitudes 200–500 m above the ground. The ornithodolite measured the polar coordinates of a bird's position in space (relative to the ground) and recorded them on magnetic tape. The vultures had air speeds between 5.4 and 39.lms−1, and sinking speeds between 0.2 and 8.3ms−1. Most of the observations fell within the theoretical boundaries of the performance area. These data are consistent with a maximum lift coefficient of 2.2 for the wings of white-backed vultures.
2
Rosen, M., and A. Hedenstrom. "Gliding flight in a jackdaw: a wind tunnel study." Journal of Experimental Biology 204, no. 6 (March 15, 2001): 1153–66. http://dx.doi.org/10.1242/jeb.204.6.1153.
Повний текст джерелаАнотація:
We examined the gliding flight performance of a jackdaw Corvus monedula in a wind tunnel. The jackdaw was able to glide steadily at speeds between 6 and 11 m s(−1). The bird changed its wingspan and wing area over this speed range, and we measured the so-called glide super-polar, which is the envelope of fixed-wing glide polars over a range of forward speeds and sinking speeds. The glide super-polar was an inverted U-shape with a minimum sinking speed (V(ms)) at 7.4 m s(−1) and a speed for best glide (V(bg)) at 8.3 m s(−)). At the minimum sinking speed, the associated vertical sinking speed was 0.62 m s(−1). The relationship between the ratio of lift to drag (L:D) and airspeed showed an inverted U-shape with a maximum of 12.6 at 8.5 m s(−1). Wingspan decreased linearly with speed over the whole speed range investigated. The tail was spread extensively at low and moderate speeds; at speeds between 6 and 9 m s(−1), the tail area decreased linearly with speed, and at speeds above 9 m s(−1) the tail was fully furled. Reynolds number calculated with the mean chord as the reference length ranged from 38 000 to 76 000 over the speed range 6–11 m s(−1). Comparisons of the jackdaw flight performance were made with existing theory of gliding flight. We also re-analysed data on span ratios with respect to speed in two other bird species previously studied in wind tunnels. These data indicate that an equation for calculating the span ratio, which minimises the sum of induced and profile drag, does not predict the actual span ratios observed in these birds. We derive an alternative equation on the basis of the observed span ratios for calculating wingspan and wing area with respect to forward speed in gliding birds from information about body mass, maximum wingspan, maximum wing area and maximum coefficient of lift. These alternative equations can be used in combination with any model of gliding flight where wing area and wingspan are considered to calculate sinking rate with respect to forward speed.
3
Thahir, Muhammad Agam, Irwandy Syofyan, and Isnaniah Isnaniah. "PENGUJIAN SINKING SPEED SERAT ALAMI." JURNAL PERIKANAN TROPIS 4, no. 1 (April 1, 2017): 93. http://dx.doi.org/10.35308/jpt.v4i1.59.
Повний текст джерелаАнотація:
The aim of this study to determine the elongation of three types of natural fibers. The method used is an experiment, by directly testing samples of the rope in the aquarium. Sinking speed value of banana stem fiber is 4.8 cm / sec, pandan leaves 3.9 cm / sec, bundung grass fibers 2.6 cm / sec. The third of these natural fibers, banana stem fibers that have the potential as for natural fibre rope material fishing gear.
4
Shan, Chenxu, Hao Tang, Nyatchouba Nsangue Bruno Thierry, Wei Liu, Feng Zhang, Meixi Zhu, Can Zhang, Liuxiong Xu, and Fuxiang Hu. "Sinking Behavior of Netting Panels Made with Various Twine Materials, Solidity Ratios, Knot Types, and Leadline Weights in Flume Tank." Journal of Marine Science and Engineering 11, no. 10 (October 12, 2023): 1972. http://dx.doi.org/10.3390/jmse11101972.
Повний текст джерелаАнотація:
Netting is an important component of fishing gear design, and its ability to sink determines the effectiveness of fishing gears such as purse seines, falling nets, and stick-held nets. Therefore, it is crucial to thoroughly investigate the sinking parameters (sinking depth and sinking speed) of the netting panel as a function of the leadline weights using various twine materials, knot types, and solidity ratios. In this study, a generalized additive model (GAM) was utilized to analyze the impact of each factor on the sinking performances of the netting. The results revealed that the sinking depth of the netting was positively correlated with sinking time and leadline weight. However, the netting featured a maximum sinking depth limit, indicating that the sinking depth would not increase beyond a leadline weight of 69.5 g. During the initial phase of the sinking process, the sinking velocity of each netting panel initially increased but gradually decreased over time. The incorporation of a leadline weight reduced sinking time. Thereby, polyester netting exhibited the shortest average sinking time. A comparison of netting types with similar solidity ratios showed that the maximum sinking depth of the nylon netting was 13.20% and 10.11% greater than that of polyethylene and polyester nettings, respectively. In addition, nylon nets’ time average sinking speed was 64.58% and 4.62% greater than that of polyethylene and polyester nettings, respectively. The analysis of the GAM model clearly showed that the leadline weight has a significant effect on the netting sinking speed and depth. To ensure that the netting can reach its maximum sinking speed, it is strongly recommended to use nylon and polyester nettings with a low solidity ratio, i.e., a lower twine diameter and greater mesh size with a higher leadline weight, when constructing fishing gear such as purse seines with higher net leadline weights.
5
Spilling, Kristian, Malte Heinemann, Mari Vanharanta, Moritz Baumann, Andrea Noche-Ferreira, Philipp Suessle, and Ulf Riebesell. "Respiration rate scales inversely with sinking speed of settling marine aggregates." PLOS ONE 18, no. 3 (March 1, 2023): e0282294. http://dx.doi.org/10.1371/journal.pone.0282294.
Повний текст джерелаАнотація:
Sinking marine aggregates have been studied for a long time to understand their role in carbon sequestration. Traditionally, sinking speed and respiration rates have been treated as independent variables, but two recent papers suggest that there is a connection albeit in contrasting directions. Here we collected recently formed (<2 days old) aggregates from sediment traps mounted underneath mesocosms during two different experiments. The mesocosms were moored off Gran Canaria, Spain (~ 27.9 N; 15.4 E) in a coastal, sub-tropical and oligotrophic ecosystem. We determined the respiration rates of organisms (mainly heterotrophic prokaryotes) attached to aggregates sinking at different velocities. The average respiration rate of fast sinking aggregates (>100 m d-1) was 0.12 d-1 ± 0.08 d-1 (SD). Slower sinking aggregates (<50 m d-1) had on average higher (p <0.001) and more variable respiration rates (average 0.31 d-1 ± 0.16 d-1, SD). There was evidence that slower sinking aggregates had higher porosity than fast sinking aggregates, and we hypothesize that higher porosity increase the settlement area for bacteria and the respiration rate. These findings provide insights into the efficiency of the biological carbon pump and help resolve the apparent discrepancy in the recent studies of the correlation between respiration and sinking speed.
6
Kloos, Heidi, and Guy C. Van Orden. "Can a Preschooler’s Mistaken Belief Benefit Learning?" Swiss Journal of Psychology 64, no. 3 (September 2005): 195–205. http://dx.doi.org/10.1024/1421-0185.64.3.195.
Повний текст джерелаАнотація:
Young children erroneously believe that differences either in mass alone or in volume alone can predict differences in sinking speed. The current study was an attempt to teach preschool children that neither mass nor volume alone is predictive for sinking speed. Instead, it is the average density of an object that can predict differences in sinking speed. Twenty-four 4-to 6-year-olds participated. In an initial phase, children’s mistaken beliefs about the effects of mass and volume on sinking speed were called to their minds. Then they were presented with demonstrations of sinking objects that disconfirmed these mistaken beliefs. The findings show that preschool children can replace mistaken beliefs and learn that two dimensions, originally thought of as being relevant, are indeed irrelevant. Children who did not perform correctly demonstrated a mass bias. The results also shed light on the origins of this bias.
7
Fitri, Amraini, Nofrizal Nofrizal, Romie Jhonnerie, and Fauzan Ramadhan. "Absorption and Sinking Speed of Artocarpus Stems Rope (Artocarpus sp.) and Carex Grass Rope (Carex sp.) in Freshwater and Seawater." Jurnal Perikanan dan Kelautan 27, no. 3 (October 4, 2022): 354. http://dx.doi.org/10.31258/jpk.27.3.354-357.
Повний текст джерелаАнотація:
Artocarpus stems (Artocarpus sp.) and Carex grass (Carex sp.) have not been applied to fishing gear materials. The fibers produced made into a rope, where this rope is used to absorption and sinking speed test in fresh water and sea water.The absorption of Artocarpus stems rope was 320.30% and 282,60% in fresh water and sea water. Meanwhile for sinking speed have a 5,78 cm/s and 5,08 cm/s for fresh water and sea water. For the Carex grass rope, the absorption in fresh water and sea water was 287,67% and 218,02%. Sinking speed value 2,97 cm/s and 2,67 cm/s for fresh water and sea water. The value of absorption and sinking speed in fresh water is higher than in sea water for both types of rope
8
Bergan, Alexander J., Gareth L. Lawson, Amy E. Maas, and Zhaohui Aleck Wang. "The effect of elevated carbon dioxide on the sinking and swimming of the shelled pteropod Limacina retroversa." ICES Journal of Marine Science 74, no. 7 (March 31, 2017): 1893–905. http://dx.doi.org/10.1093/icesjms/fsx008.
Повний текст джерелаАнотація:
Abstract Shelled pteropods are planktonic molluscs that may be affected by ocean acidification. Limacina retroversa from the Gulf of Maine were used to investigate the impact of elevated carbon dioxide (CO2) on shell condition as well as swimming and sinking behaviours. Limacina retroversa were maintained at either ambient (ca. 400 µatm) or two levels of elevated CO2 (800 and 1200 µatm) for up to 4 weeks, and then examined for changes in shell transparency, sinking speed, and swimming behaviour assessed through a variety of metrics (e.g. speed, path tortuosity, and wing beat frequency). After exposures to elevated CO2 for as little as 4 d, the pteropod shells were significantly darker and more opaque in the elevated CO2 treatments. Sinking speeds were significantly slower for pteropods exposed to medium and high CO2 in comparison to the ambient treatment. Swimming behaviour showed less clear patterns of response to treatment and duration of exposure, but overall, swimming did not appear to be hindered under elevated CO2. Sinking is used by L. retroversa for predator evasion, and altered speeds and increased visibility could increase the susceptibility of pteropods to predation.
9
Kriest, I., and A. Oschlies. "On the treatment of particulate organic matter sinking in large-scale models of marine biogeochemical cycles." Biogeosciences 5, no. 1 (January 25, 2008): 55–72. http://dx.doi.org/10.5194/bg-5-55-2008.
Повний текст джерелаАнотація:
Abstract. Various functions have been suggested and applied to represent the sedimentation and remineralisation of particulate organic matter (POM) in numerical ocean models. Here we investigate some representations commonly used in large-scale biogeochemical models: a constant sinking speed, a sinking speed increasing with depth, a spectrum of particles with different size and different size-dependent sinking velocities, and a model that assumes a power law particle size distribution everywhere in the water column. The analysis is carried out for an idealised one-dimensional water column, under stationary boundary conditions for surface POM. It focuses on the intrinsic assumptions of the respective sedimentation function and their effect on POM mass, mass flux, and remineralisation profiles. A constant and uniform sinking speed does not appear appropriate for simulations exceeding a few decades, as the sedimentation profile is not consistent with observed profiles. A spectrum of size classes, together with size-dependent sinking and constant remineralisation, causes the sinking speed of total POM to increase with depth. This increase is not strictly linear with depth. Its particular form will further depend on the size distribution of the POM ensemble at the surface. Assuming a power law particle size spectrum at the surface, this model results in unimodal size distributions in the ocean interior. For the size-dependent sinking model, we present an analytic integral over depth and size that can explain regional variations of remineralisation length scales in response to regional patterns in trophodynamic state.
10
Kriest, I., and A. Oschlies. "On the treatment of particulate organic matter sinking in large-scale models of marine biogeochemical cycles." Biogeosciences Discussions 4, no. 4 (August 28, 2007): 3005–40. http://dx.doi.org/10.5194/bgd-4-3005-2007.
Повний текст джерелаАнотація:
Abstract. Various functions have been suggested and applied to represent the sedimentation and remineralisation of particulate organic matter (POM) in numerical ocean models. Here we investigate some representations commonly used in large-scale biogeochemical models: a constant sinking speed, a sinking speed increasing with depth, a spectrum of particles with different size and different size-dependent sinking velocities, and a model that assumes a power-law particle size distribution everywhere in the water column. The analysis is carried out for an idealised one-dimensional water column, under stationary boundary conditions for surface POM. It focuses on the intrinsic assumptions of the respective sedimentation function and their effect on POM mass, mass flux, and remineralisation profiles. A constant and uniform sinking speed does not appear appropriate for simulations exceeding a few decades, as the sedimentation profile is not consistent with observed profiles. A spectrum of size classes, together with size-dependent sinking and constant remineralisation, causes the sinking speed of total POM to increase with depth. This increase is not strictly linear with depth. Its particular form will further depend on the size distribution of the POM ensemble at the surface. Assuming a power-law particle size spectrum at the surface, this model results in unimodal size distributions in the ocean interior. For the size-dependent sinking model, we present an analytic integral over depth and size that can explain regional variations of remineralisation length scales in response to regional patterns in trophodynamic state.
11
Du Clos, Kevin T., Lee Karp-Boss, Tracy A. Villareal, and Brad J. Gemmell. "Coscinodiscus wailesii mutes unsteady sinking in dark conditions." Biology Letters 15, no. 3 (March 2019): 20180816. http://dx.doi.org/10.1098/rsbl.2018.0816.
Повний текст джерелаАнотація:
Several species of large, centric diatoms exhibit an unsteady sinking behaviour characterized by order-of-magnitude oscillations in sinking speed that occur over seconds. We show that under nutrient-depleted conditions, Coscinodiscus wailesii exhibits significantly stronger unsteady sinking behaviour in the light than in the dark. Results suggest that regulating unsteady sinking in response to irradiance as well as nutrient conditions may help C. wailesii balance its requirements for light and nutrients, which are often spatially separated.
12
Crête, M., and S. Larivière. "Estimating the costs of locomotion in snow for coyotes." Canadian Journal of Zoology 81, no. 11 (November 1, 2003): 1808–14. http://dx.doi.org/10.1139/z03-182.
Повний текст джерелаАнотація:
Carnivores living in areas of deep snow face additional energy expenditures during winter owing to increased locomotory costs. Such costs may vary in function of snow depth and hardness (sinking depth of animal) and travel speed. We estimated energetic costs of locomotion through snow in wild coyotes (Canis latrans) using three coyote-sized domestic dogs (Canis familiaris) to develop regression models predicting heart rate (as surrogate for energy expenditure) in relation to sinking depth and travel speed. In the absence of snow, heart rates of dogs increased linearly with travel speed (R2 = 0.24), whereas when snow was present, track sinking depth affected heart rate substantially more than did travel speed. To assess whether our results with domestic dogs could help explain the behaviour of wild coyotes, we snow-tracked coyotes in southeastern Quebec, Canada, during two winters. During a normal harsh winter, coyotes relied on artificially packed snow (snowmobile and animal trails) more than during a mild winter. Coyotes typically exerted a fine-scale selection for snow depth and hardness that effectively reduced their sinking depth by ~2 cm. We estimated that travelling over snow increased coyote heart rate by 4%–6% in comparison with locomotion on hard surfaces, whereas fine-scale selection saved a similar amount of extra energy. We hypothesize that the use of snow packed by anthropogenic activities, especially snowmobile trails, may not only facilitate coyote movements in deep snow environments but also allow occupation of marginal habitats such as forested areas of northeastern North America.
13
Pridmore, Peter A., and Peter H. Hoffmann. "The aerodynamic performance of the feathertail glider, Acrobates pygmaeus (Marsupialia: Acrobatidae)." Australian Journal of Zoology 62, no. 1 (2014): 80. http://dx.doi.org/10.1071/zo13071.
Повний текст джерелаАнотація:
Photographic and videographic investigations of the aerodynamic performance of four captive adult Acrobates pygmeus are described. During short (1–4 m) glides, steep angles of descent (>45°) and large angles of attack (up to 50°) were used mid-flight, and the possums failed to achieve steady velocities. During longer (>10 m) glides steady velocities of 5.3–7.5 m s–1 were achieved, and glide angles of 21–42° and angles of attack between 36° and 45° were used. The best (lowest) glide angles used at steady velocity were similar to those documented in sugar gliders, but involved lower air speeds. During steady gliding the forelimbs of Acrobates assumed an ‘elbows-out’ disposition similar to that of Petauroides volans, and unlike that of petaurid gliders. A glide polar for Acrobates shows that it uses lower air speeds and higher sinking speeds than other gliding animals for which polars are available (several birds and one bat). Few data on the radius of turn and sinking speed were obtained; nevertheless, in accord with theory, sinking speeds were higher during tighter turns. During flight the feather-like tail was used to generate pitching movements and adjust the angle of attack and hence glide angle. However, the control of turns seems to be achieved primarily through limb adjustments.
14
Meng, Qiao, Ke Zhong, and Mingzhi Sun. "Dynamic Response Analysis of Airport Pavement under Impact Loading." Applied Sciences 13, no. 9 (May 5, 2023): 5723. http://dx.doi.org/10.3390/app13095723.
Повний текст джерелаАнотація:
The safety of the airport runway, as an infrastructure, is of considerable concern. The existing research has problems of hysteresis and unreasonable load application. In this paper, ANSYS is used to construct a coupled tire–pavement model to study the dynamic characteristics of airport asphalt pavements under impact loading. Taking the Boeing 737–800 as an example, the impact of an aircraft landing on an airport pavement is simulated by applying a dynamic load to the landing gear. The effects of tire pressure, landing pitch angle, and sinking speed on the dynamic response of the airport runway are investigated. The effects of each factor of the airport pavement are analyzed by comparing the maximum effective stress, effective strain, and displacement in the vertical direction at the same position of different structures. The results show that when the tire pressure is 2.0 MPa, the maximum values of effective stress, effective strain, and vertical displacement increase by 29.8%, 19.1%, and 22.2%, respectively, compared with 1.0 MPa. The maximum values of effective stress, effective strain, and vertical displacement at the 3.0 m/s sinking speed increase by 25.2%, 93.1%, and 77.1%, respectively, compared with that at the sinking speed of 1 m/s, which indicates that the effect of sinking speed on the dynamic response of the pavement is more significant. However, the change in the landing pitch angle has little impact on the response parameters of the pavement. Meanwhile, the flexural tensile stress at the bottom of the surface and the equivalent effect at the top of the soil foundation must be considered in the design of the airport pavement structure.
15
Zhou, Jin, Jianjiang Zeng, Jichang Chen, and Mingbo Tong. "Analysis of Global Sensitivity of Landing Variables on Landing Loads and Extreme Values of the Loads in Carrier-Based Aircrafts." International Journal of Aerospace Engineering 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/2105682.
Повний текст джерелаАнотація:
When a carrier-based aircraft is in arrested landing on deck, the impact loads on landing gears and airframe are closely related to landing states. The distribution and extreme values of the landing loads obtained during life-cycle analysis provide an important basis for buffering parameter design and fatigue design. In this paper, the effect of the multivariate distribution was studied based on military standards and guides. By establishment of a virtual prototype, the extended Fourier amplitude sensitivity test (EFAST) method is applied on sensitivity analysis of landing variables. The results show that sinking speed and rolling angle are the main influencing factors on the landing gear’s course load and vertical load; sinking speed, rolling angle, and yawing angle are the main influencing factors on the landing gear’s lateral load; and sinking speed is the main influencing factor on the barycenter overload. The extreme values of loads show that the typical condition design in the structural strength analysis is safe. The maximum difference value of the vertical load of the main landing gear is 12.0%. This research may provide some reference for structure design of landing gears and compilation of load spectrum for carrier-based aircrafts.
16
Iversen, M. H., and H. Ploug. "Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes." Biogeosciences 10, no. 6 (June 20, 2013): 4073–85. http://dx.doi.org/10.5194/bg-10-4073-2013.
Повний текст джерелаАнотація:
Abstract. Most deep ocean carbon flux profiles show low and almost constant fluxes of particulate organic carbon (POC) in the deep ocean. However, the reason for the non-changing POC fluxes at depths is unknown. This study presents direct measurements of formation, degradation, and sinking velocity of diatom aggregates from laboratory studies performed at 15 °C and 4 °C during a three-week experiment. The average carbon-specific respiration rate during the experiment was 0.12 ± 0.03 at 15 °C, and decreased 3.5-fold when the temperature was lowered to 4 °C. No direct influence of temperature on aggregate sinking speed was observed. Using the remineralisation rate measured at 4 °C and an average particle sinking speed of 150 m d−1, calculated carbon fluxes were similar to those collected in deep ocean sediment traps from a global data set, indicating that temperature plays a major role for deep ocean fluxes of POC.
17
Iversen, M. H., and H. Ploug. "Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes." Biogeosciences Discussions 10, no. 1 (January 8, 2013): 371–99. http://dx.doi.org/10.5194/bgd-10-371-2013.
Повний текст джерелаАнотація:
Abstract. Most deep ocean carbon flux profiles show low and almost constant fluxes of particulate organic carbon (POC) in the deep ocean. However, the reason for the seemingly non-changing POC fluxes at depths is unknown. This study presents direct measurements of formation, degradation, and sinking velocity of diatom aggregates from laboratory studies performed at 15 °C and 4 °C during a three week experiment. The average carbon-specific respiration rate during the experiment was 0.12 ± 0.03 at 15 °C, and decreased 3.5-fold when the temperature was lowered to 4 °C. No direct influence of temperature on aggregate sinking speed was observed. Using the remineralisation rate measured at 4 °C and an average particle sinking speed of 150 m d−1, calculated carbon fluxes were similar to those collected in deep ocean sediment traps from a global data set, indicating that temperature plays a major role for deep ocean fluxes of POC.
18
Cetin, Serkan, Akira Okada, and Yoshiyuki Uno. "Electrode Jump Motion in Linear Motor Equipped Die-Sinking EDM." Journal of Manufacturing Science and Engineering 125, no. 4 (November 1, 2003): 809–15. http://dx.doi.org/10.1115/1.1615793.
Повний текст джерелаАнотація:
The effects of electrode jump parameters on machining speed and depth were experimentally investigated in linear motor equipped electrical discharge machining. A new definition named “Machining speed break point” is introduced, theoretically calculated from a proposed electrode jump and debris exclusion model, and compared with the experimental results. Additionally, an algorithm is developed to calculate the accumulation of debris in machining gap. The algorithm showed that the debris concentration in gap rises suddenly before the machining speed break point.
19
Dong, Tingting, and Tian Li. "Numerical Comparison in Aerodynamic Drag and Noise of High-Speed Pantographs with or without Platform Sinking." Applied Sciences 13, no. 10 (May 19, 2023): 6213. http://dx.doi.org/10.3390/app13106213.
Повний текст джерелаАнотація:
Flat roofs and platform sinking are two common installation configurations for high-speed pantographs. The cavity formed by the platform sinking is a potential source of aerodynamic drag and noise. In this paper, the shape of the rectangular cavity is optimized, and the aerodynamic performance of the high-speed pantograph with or without platform sinking is compared and discussed based on the optimized cavity results. The flow field and sound propagation are predicted by the improved delayed detached eddy simulation (IDDES) method and the FW-H equation. The results show that the rectangular cavity produces the largest aerodynamic drag and radiation noise. The upstream, downstream, and bottom surfaces of the cavity can be optimized by rounded and sloped edges to reduce aerodynamic drag and noise. The unstable shear flow and recirculation zone formed by flow separation and reattachment can be reduced by modifying the upstream and downstream surfaces of the cavity. In addition, the vortex in front of the downstream surface of the cavity can be reduced or even eliminated by modifying the bottom surface. When the upstream and downstream surfaces of the cavity are rounded and the bottom surface is sloped (R/H = 0.8), the aerodynamic performance of the cavity is better. Compared with the pantograph installed on the flat roof, the aerodynamic drag and noise of the pantograph with platform sinking are significantly reduced due to the shielding of the lower structure by the cavity, and the total drag and noise are reduced by 5.22% and 1.45 dBA, respectively.
20
Barlet, A., and N. Malhomme. "Suction-ejection of a ping-pong ball in a falling water-filled cup." Emergent Scientist 6 (2022): 2. http://dx.doi.org/10.1051/emsci/2022002.
Повний текст джерелаАнотація:
Dropping a water-filled cup with a ping-pong ball inside to the ground expels the ball much higher than its initial height. During free fall, the absence of gravity in the reference frame of the cup makes capillary forces dominant, causing the ball to be sucked into water. At impact, the high velocity ejection is due to the strong Archimedes’ force caused by vertical acceleration. In this paper, we study the dynamics of the capillary sinking of the ball during free fall and the ejection speed at impact, using tracking and high-speed imaging. In particular, we show that at short-time, the sinking is governed by capillary and added mass forces.
21
Schmidt, K., C. L. De La Rocha, M. Gallinari, and G. Cortese. "Not all calcite ballast is created equal: differing effects of foraminiferan and coccolith calcite on the formation and sinking of aggregates." Biogeosciences 11, no. 1 (January 9, 2014): 135–45. http://dx.doi.org/10.5194/bg-11-135-2014.
Повний текст джерелаАнотація:
Abstract. Correlation between particulate organic carbon (POC) and calcium carbonate sinking through the deep ocean has led to the idea that ballast provided by calcium carbonate is important for the export of POC from the surface ocean. While this idea is certainly to some extent true, it is worth considering in more nuance, for example, examining the different effects on the aggregation and sinking of POC of small, non-sinking calcite particles like coccoliths and large, rapidly sinking calcite like planktonic foraminiferan tests. We have done that here in a simple experiment carried out in roller tanks that allow particles to sink continuously without being impeded by container walls. Coccoliths were efficiently incorporated into aggregates that formed during the experiment, increasing their sinking speed compared to similarly sized aggregates lacking added calcite ballast. The foraminiferan tests, which sank as fast as 700 m d−1, became associated with only very minor amounts of POC. In addition, when they collided with other, larger, foram-less aggregates, they fragmented them into two smaller, more slowly sinking aggregates. While these effects were certainly exaggerated within the confines of the rolling tanks, they clearly demonstrate that calcium carbonate ballast is not just calcium carbonate ballast – different forms of calcium carbonate ballast have notably different effects on POC aggregation, sinking, and export.
22
Schmidt, K., C. L. De La Rocha, M. Gallinari, and G. Cortese. "Not all calcite ballast is created equal: differing effects of foraminiferan and coccolith calcite on the formation and sinking of aggregates." Biogeosciences Discussions 10, no. 9 (September 10, 2013): 14861–85. http://dx.doi.org/10.5194/bgd-10-14861-2013.
Повний текст джерелаАнотація:
Abstract. Correlation between particulate organic carbon (POC) and calcium carbonate sinking through the deep ocean has led to the idea that ballast provided by calcium carbonate is important for the export of POC from the surface ocean. While this idea is certainly to some extent true, it is worth considering in more nuance, for example, examining the different effects on the aggregation and sinking of POC of small, non-sinking calcite particles like coccoliths and large, rapidly sinking calcite like planktonic foraminiferan tests. We have done that here in a simple experiment carried out in roller tanks that allow particles to sink continuously without being impeded by container walls. Coccoliths were efficiently incorporated into aggregates that formed during the experiment, increasing their sinking speed compared to similarly sized aggregates lacking added calcite ballast. The foraminiferan tests, which sank as fast as 700 m d−1, became associated with only very minor amounts of POC. In addition, when they collided with other, larger, foraminferan-less aggregates, they fragmented them into two smaller, more slowly sinking aggregates. While these effects were certainly exaggerated within the confines of the roller tanks, they clearly demonstrate that calcium carbonate ballast is not just calcium carbonate ballast- different forms of calcium carbonate ballast have notably different effects on POC aggregation, sinking, and export.
23
Lebrato, Mario, Pedro de Jesus Mendes, Deborah K. Steinberg, Joan E. Cartes, Bethan M. Jones, Laura M. Birsa, Roberto Benavides, and Andreas Oschlies. "Jelly biomass sinking speed reveals a fast carbon export mechanism." Limnology and Oceanography 58, no. 3 (May 2013): 1113–22. http://dx.doi.org/10.4319/lo.2013.58.3.1113.
Повний текст джерела
24
Asper, Vernon L. "Measuring the flux and sinking speed of marine snow aggregates." Deep Sea Research Part A. Oceanographic Research Papers 34, no. 1 (January 1987): 1–17. http://dx.doi.org/10.1016/0198-0149(87)90117-8.
Повний текст джерела
25
Millward, A. "A Preliminary Design Method for the Prediction of Squat in Shallow Water." Marine Technology and SNAME News 27, no. 01 (January 1, 1990): 10–19. http://dx.doi.org/10.5957/mt1.1990.27.1.10.
Повний текст джерелаАнотація:
The variation of squat with speed in shallow water has been shown to be important with the sinking of the ferry Herald of Free Enterprise, yet it is not easily predictable, particularly at higher speeds. The squat characteristics of a number of ship models have been analyzed and an empirical method of predicting the squat at subcritical speeds has been devised. This method has been compared with data from the model tests of the Herald of Free Enterprise and has shown good agreement.
26
Schwinger, Jörg, Nadine Goris, Jerry F. Tjiputra, Iris Kriest, Mats Bentsen, Ingo Bethke, Mehmet Ilicak, Karen M. Assmann, and Christoph Heinze. "Evaluation of NorESM-OC (versions 1 and 1.2), the ocean carbon-cycle stand-alone configuration of the Norwegian Earth System Model (NorESM1)." Geoscientific Model Development 9, no. 8 (August 2, 2016): 2589–622. http://dx.doi.org/10.5194/gmd-9-2589-2016.
Повний текст джерелаАнотація:
Abstract. Idealised and hindcast simulations performed with the stand-alone ocean carbon-cycle configuration of the Norwegian Earth System Model (NorESM-OC) are described and evaluated. We present simulation results of three different model configurations (two different model versions at different grid resolutions) using two different atmospheric forcing data sets. Model version NorESM-OC1 corresponds to the version that is included in the NorESM-ME1 fully coupled model, which participated in CMIP5. The main update between NorESM-OC1 and NorESM-OC1.2 is the addition of two new options for the treatment of sinking particles. We find that using a constant sinking speed, which has been the standard in NorESM's ocean carbon cycle module HAMOCC (HAMburg Ocean Carbon Cycle model), does not transport enough particulate organic carbon (POC) into the deep ocean below approximately 2000 m depth. The two newly implemented parameterisations, a particle aggregation scheme with prognostic sinking speed, and a simpler scheme that uses a linear increase in the sinking speed with depth, provide better agreement with observed POC fluxes. Additionally, reduced deep ocean biases of oxygen and remineralised phosphate indicate a better performance of the new parameterisations. For model version 1.2, a re-tuning of the ecosystem parameterisation has been performed, which (i) reduces previously too high primary production at high latitudes, (ii) consequently improves model results for surface nutrients, and (iii) reduces alkalinity and dissolved inorganic carbon biases at low latitudes. We use hindcast simulations with prescribed observed and constant (pre-industrial) atmospheric CO2 concentrations to derive the past and contemporary ocean carbon sink. For the period 1990–1999 we find an average ocean carbon uptake ranging from 2.01 to 2.58 Pg C yr−1 depending on model version, grid resolution, and atmospheric forcing data set.
27
Pankratenko, Alexander, and Alexander Isaev. "The Analysis of the Stress-Strain State of the System “Equipment Complex - Support - Rock Mass” in the Bottomhole Area of the Shaft." E3S Web of Conferences 41 (2018): 01038. http://dx.doi.org/10.1051/e3sconf/20184101038.
Повний текст джерелаАнотація:
The development of new deposits enterprises requires the construction of deep and super deep vertical shafts. The duration of their construction reaches 8 - 10 years with multi-billion capital investments. To reduce the payback period of these costs, it is necessary to develop and implement effective solutions to increase the speed of sinking operations through the wide introduction of brand-new mechanized equipment complexes. In response to the sinking in the bottomhole area of the shaft a complex, the following geotechnological system is being formed: "tunneling system - support - rock mass", the regularities of which require further study. For these purposes, an analytical method for calculating the shaft support can be used in the context of consideration of a planar contact problem at various phases of the system operation. The mutual coordination of individual phases in accordance with the classical concepts of the underground structures mechanics is possible with the help of a correction factor to the magnitude of horizontal stresses in the rock mass. In this paper we developed the algorithm which determines this coefficient, taking into account the influence of the main technological factors: the jack system pressure of the complex and the speed of sinking.
28
Pankratenko, Alexander, Mikhail Pleshko, and Alexander Isaev. "Analytical analysis of the stress-strain state of the system “mechanized equipment complex - support – rock mass” in the bottomhole area of the shaft." MATEC Web of Conferences 193 (2018): 02026. http://dx.doi.org/10.1051/matecconf/201819302026.
Повний текст джерелаАнотація:
The development of new deposits requires the construction of deep and super deep vertical shafts. The duration of their construction reaches 8 - 10 years with multi-billion capital investments. To reduce the payback period of these costs, it is necessary to develop and implement effective solutions to increase the speed of sinking operations through the wide introduction of brand-new mechanized equipment complexes. In response to the sinking in the bottomhole area of the shaft, the following geotechnical system is being formed: “tunnelling system - support - rock mass”, the regularities of which require further study. For these purposes, an analytical method for calculating the shaft support can be used in the context of consideration of a planar contact problem at various phases of the system operation. The mutual coordination of individual phases in accordance with the classical concepts of the underground structures mechanics is possible using a correction factor to the magnitude of horizontal stresses in the rock mass. In this paper, we developed the algorithm which determines this coefficient, taking into account the influence of the main technological factors: the pressure of the jack system of the complex and the speed of sinking.
29
Liu, Hongkang, Siqi Zhou, Rongrong Chen, Zhuolun Li, Shishang Zhang, and Yatian Zhao. "Numerical Study on the Aeroacoustic Performance of Different Diversion Strategies in the Pantograph Area of High-Speed Trains at 400 km/h." Applied Sciences 12, no. 21 (October 22, 2022): 10702. http://dx.doi.org/10.3390/app122110702.
Повний текст джерелаАнотація:
The speed increase in high-speed trains is a critical procedure in the promotion of high-speed railway technology. As an indispensable and complex structure of high-speed trains, the pantograph’s aerodynamic drag and noise is a significant limitation in the speed increase process of high-speed trains. In the present study, the hybrid method of large eddy simulation (LES) and Ffowcs Williams-Hawkings (FW-H) acoustic analogy is applied to analyze the aerodynamic and aeroacoustic performances of pantograph installed in different ways, i.e., sinking platform and fairing. The results of simulation show that the application of pantograph fairing can reduce the aerodynamic drag greatly. In addition, compared with the pantographs installed alone on the train roof, the installation of the sinking platform brings about 2 dBA reduction in sound pressure level (SPL). Meanwhile, the utilization of the pantograph fairing mainly decreases the noise in the frequency band above 1000 Hz and the largest SPL reduction is up to 3 dBA among the monitoring points. Further analysis shows that the influence of different diversion strategies on the spectral characteristics actually attenuates the dominant frequency of the panhead. In the horizontal plane, the noise directivity of the pantograph installed with a fairing is similar to the pantograph installed alone on the train roof.
30
Keil, R. G., J. Neibauer, C. Biladeau, K. van der Elst, and A. H. Devol. "A multiproxy approach to understanding the "enhanced" flux of organic matter through the oxygen deficient waters of the Arabian Sea." Biogeosciences Discussions 12, no. 20 (October 22, 2015): 17051–92. http://dx.doi.org/10.5194/bgd-12-17051-2015.
Повний текст джерелаАнотація:
Abstract. Free-drifting sediment net traps were deployed 14 times at depths between 80 and 500 m for 1–3 days each during the late monsoon/intermonsoon transition in the central Arabian Sea. Two locations (19.5 and 15.5° N) were within the permanently oxygen deficient zone, and a third (11° N) had a shallow and thin oxygen minimum. The secondary nitrite maximum, which serves as a tracer of the oxygen deficient zone (ODZ) zone, thinned from ∼ 250 m thick at stations 19.5 and 15.5° N to ∼ 50 m thick at station 11° N. Overall, organic carbon fluxes ranged from 13.2 g m2 yr−1 at 80 m to a minimum of 1.1 g m2 yr−1 at 500 m. Fluxes at the more oxygenated 11° N station attenuate faster than within the permanent ODZ. Martin curve attenuation coefficients for 19.5 and 15.5° N are 0.59 and 0.63 and for 11° N it is 0.98. At least six potential mechanisms might explain why sinking particles sinking through the ODZ are more effectively transferred to depth; (M1) oxygen effects, (M2) microbial loop efficiencies and chemoautotrophy, (M3) changes in zooplankton dynamics, (M4) additions of ballast that might sorb and protect organic matter from decay, (M5) inputs of refractory organic matter, and (M6) changes in sinking speeds. These mechanisms are intertwined, and were explored using a combination of mineral (XPS) and organic matter characterizations of the sinking material and ship-board incubation experiments. Evidence was found supporting an oxygen effect and/or changes in the efficiency of the microbial loop including the addition of chemoautotrophic carbon to the sinking flux in the upper 500 m. Less evidence was found for the other potential mechanisms. A simple conceptual model consistent with our and other recent data suggests that the upper ODZ microbial community determines the initial flux attenuation, and that deeper in the water column zooplankton and sinking speed become more important. The exact interplay between the various mechanisms remains to be further evaluated.
31
Lee, Jihoon, Chun-Woo Lee, Ludvig Karlsen, Taeho Kim, and Jeehun Song. "Which factors strongly influence the sinking speed of a demersal longline?" Aquatic Conservation: Marine and Freshwater Ecosystems 24, no. 1 (September 30, 2013): 118–34. http://dx.doi.org/10.1002/aqc.2399.
Повний текст джерела
32
Gehlen, M., L. Bopp, N. Emprin, O. Aumont, C. Heinze, and O. Ragueneau. "Reconciling surface ocean productivity, export fluxes and sediment composition in a global biogeochemical ocean model." Biogeosciences Discussions 3, no. 3 (June 28, 2006): 803–36. http://dx.doi.org/10.5194/bgd-3-803-2006.
Повний текст джерелаАнотація:
Abstract. This study focuses on an improved representation of the biological soft tissue pump in the global three-dimensional biogeochemical ocean model PISCES. We compare three parameterizations of particle dynamics: (1) the model standard version including two particle size classes, aggregation-disaggregation and prescribed sinking speed; (2) an aggregation-disaggregation model with a particle size spectrum and prognostic sinking speed; (3) a mineral ballast parameterization with no size classes, but prognostic sinking speed. In addition, the model includes a description of surface sediments and organic carbon early diagenesis. The integrated representation of material fluxes from the productive surface ocean down to the sediment-water interface allows taking advantage of surface ocean observations, sediment trap data and exchange fluxes at the sediment-water interface. The capability of the model to reproduce yearly averaged particulate organic carbon fluxes and benthic oxygen demand does at first order not dependent on the resolution of the particle size spectrum. Model results obtained with the standard version and with the one including a particle size spectrum and prognostic sinking speed are not significantly different. Both model versions overestimate particulate organic carbon between 1000 and 2000 m, while deep fluxes are of the correct order of magnitude. Predicted benthic oxygen fluxes correspond with respect to their large scale distribution and magnitude to data based estimates. Modeled particulate organic C fluxes across the mesopelagos are most sensitive to the intensity of zooplankton flux feeding. An increase of the intensity of flux feeding in the standard version results in lower mid- and deep-water particulate organic carbon fluxes, shifting model results to an underestimation of particulate organic carbon fluxes in the deep. The corresponding benthic oxygen fluxes are too low. The model version including the mineral ballast parameterization yields an improved fit between modeled and observed particulate organic carbon fluxes below 2000 m and down to the sediment-water interface. Our results suggest that aggregate formation alone might not be sufficient to drive an intense biological pump. The later is most likely driven by the combined effect of aggregate formation and mineral ballasting.
33
Gehlen, M., L. Bopp, N. Emprin, O. Aumont, C. Heinze, and O. Ragueneau. "Reconciling surface ocean productivity, export fluxes and sediment composition in a global biogeochemical ocean model." Biogeosciences 3, no. 4 (November 9, 2006): 521–37. http://dx.doi.org/10.5194/bg-3-521-2006.
Повний текст джерелаАнотація:
Abstract. This study focuses on an improved representation of the biological soft tissue pump in the global three-dimensional biogeochemical ocean model PISCES. We compare three parameterizations of particle dynamics: (1) the model standard version including two particle size classes, aggregation-disaggregation and prescribed sinking speed; (2) an aggregation-disaggregation model with a particle size spectrum and prognostic sinking speed; (3) a mineral ballast parameterization with no size classes, but prognostic sinking speed. In addition, the model includes a description of surface sediments and organic carbon early diagenesis. Model output is compared to data or data based estimates of ocean productivity, pe-ratios, particle fluxes, surface sediment bulk composition and benthic O2 fluxes. Model results suggest that different processes control POC fluxes at different depths. In the wind mixed layer turbulent particle coagulation appears as key process in controlling pe-ratios. Parameterization (2) yields simulated pe-ratios that compare well to observations. Below the wind mixed layer, POC fluxes are most sensitive to the intensity of zooplankton flux feeding, indicating the importance of zooplankton community composition. All model parameters being kept constant, the capability of the model to reproduce yearly mean POC fluxes below 2000 m and benthic oxygen demand does at first order not dependent on the resolution of the particle size spectrum. Aggregate formation appears essential to initiate an intense biological pump. At great depth the reported close to constant particle fluxes are most likely the result of the combined effect of aggregate formation and mineral ballasting.
34
Lindemann, Christian, Andre Visser, and Patrizio Mariani. "Dynamics of phytoplankton blooms in turbulent vortex cells." Journal of The Royal Society Interface 14, no. 136 (November 2017): 20170453. http://dx.doi.org/10.1098/rsif.2017.0453.
Повний текст джерелаАнотація:
Turbulence and coherent circulation structures, such as submesoscale and mesoscale eddies, convective plumes and Langmuir cells, play a critical role in shaping phytoplankton spatial distribution and population dynamics. We use a framework of advection–reaction–diffusion equations to investigate the effects of turbulent transport on the phytoplankton population growth and its spatial structure in a vertical two-dimensional vortex flow field. In particular, we focus on how turbulent flow velocities and sinking influence phytoplankton growth and biomass aggregation. Our results indicate that conditions in mixing and growth of phytoplankton can drive different vertical spatial structures in the mixed layer, with the depth of the mixed layer being a critical factor to allow coexistence of populations with different sinking speed. With increasing mixed layer depth, positive growth for sinking phytoplankton can be maintained with increasing turbulent flow velocities, allowing the apparently counter-intuitive persistence of fast sinking phytoplankton populations in highly turbulent and deep mixed layers. These dynamics demonstrate the role of considering advective transport within a turbulent vortex and can help to explain observed phytoplankton biomass during winter in the North Atlantic, where the overturn of deep convection has been suggested to play a critical role in phytoplankton survival.
35
Phonekeo, Sulisay, Nathan Mlot, Daria Monaenkova, David L. Hu, and Craig Tovey. "Fire ants perpetually rebuild sinking towers." Royal Society Open Science 4, no. 7 (July 2017): 170475. http://dx.doi.org/10.1098/rsos.170475.
Повний текст джерелаАнотація:
In the aftermath of a flood, fire ants, Solenopsis invicta , cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support. The towers are bell shaped, consistent with towers of constant strength such as the Eiffel tower, where each element bears an equal load. However, unlike the Eiffel tower, the ant tower is built through a process of trial and error, whereby failed portions avalanche until the final shape emerges. High-speed and novel X-ray videography reveal that the tower constantly sinks and is rebuilt, reminiscent of large multicellular systems such as human skin. We combine the behavioural rules that produce rafts on water with measurements of adhesion and attachment strength to model the rate of growth of the tower. The model correctly predicts that the growth rate decreases as the support diameter increases. This work may inspire the design of synthetic swarms capable of building in vertical layers.
36
Niazi Ardekani, M., G. Sardina, L. Brandt, L. Karp-Boss, R. N. Bearon, and E. A. Variano. "Sedimentation of inertia-less prolate spheroids in homogenous isotropic turbulence with application to non-motile phytoplankton." Journal of Fluid Mechanics 831 (October 13, 2017): 655–74. http://dx.doi.org/10.1017/jfm.2017.670.
Повний текст джерелаАнотація:
Phytoplankton are the foundation of aquatic food webs. Through photosynthesis, phytoplankton draw down $\text{CO}_{2}$ at magnitudes equivalent to forests and other terrestrial plants and convert it to organic material that is then consumed by other planktonic organisms in higher trophic levels. Mechanisms that affect local concentrations and velocities are of primary significance to many encounter-based processes in the plankton, including prey–predator interactions, fertilization and aggregate formation. We report results from simulations of sinking phytoplankton, considered as elongated spheroids, in homogenous isotropic turbulence to answer the question of whether trajectories and velocities of sinking phytoplankton are altered by turbulence. We show in particular that settling spheroids with physical characteristics similar to those of diatoms weakly cluster and preferentially sample regions of downwelling flow, corresponding to an increase of the mean settling speed with respect to the mean settling speed in quiescent fluid. We explain how different parameters can affect the settling speed and what underlying mechanisms might be involved. Interestingly, we observe that the increase in the aspect ratio of the prolate spheroids can affect the clustering and the average settling speed of particles by two mechanisms: first is the effect of aspect ratio on the rotation rate of the particles, which saturates faster than the second mechanism of increasing drag anisotropy.
37
Praneetpongrung, Chaiya, Yasushi Fukuzawa, and Shigeru Nagasawa. "Effects of Combined Ultrasonic Vibration during the Sinking EDM Process for Cemented Carbide." Advanced Materials Research 76-78 (June 2009): 657–63. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.657.
Повний текст джерелаАнотація:
In recent years, to improve the electrical discharge machining properties, several trials have been applied with the ultrasonic vibration system which was combined on the sinking electrical discharge machine. In this paper, the effects of the ultrasonic vibration were investigated with the designed sinking EDM machine. Some experimental parameters of tool electrode polarity, rotational workpiece speed and directions were examined during the sinking EDM process on the cemented carbide material of G5. Material removal rate, electrode wear ratio and surface roughness were estimated as the machining properties under finishing machining conditions. The experiments were carried out on ultrasonic longitudinal frequency 59 kHz and electrode spindle till 1,000 rpm. Two rotational apparatuses were used simultaneously on the opposite rotational direction during discharge machining. The discharge conditions were estimated with the waveforms analysis. As the results, the EDM device system which was combined ultrasonic vibration, improved the material removal rate and surface roughness of the EDMed workpiece.
38
Keil, Richard G., Jacquelyn A. Neibauer, Christina Biladeau, Kelsey van der Elst, and Allan H. Devol. "A multiproxy approach to understanding the "enhanced" flux of organic matter through the oxygen-deficient waters of the Arabian Sea." Biogeosciences 13, no. 7 (April 8, 2016): 2077–92. http://dx.doi.org/10.5194/bg-13-2077-2016.
Повний текст джерелаАнотація:
Abstract. Free-drifting sediment net traps were deployed 14 times at depths between 80 and 500 m for 1–3 days each during the late monsoon–intermonsoon transition in the central Arabian Sea. Two locations (19.5 and 15.5° N) were within the permanently oxygen-deficient zone (ODZ), and a third (11° N) had a shallow and thin oxygen minimum. The secondary nitrite maximum, which serves as a tracer of the ODZ, thinned from ∼ 250 m thick at stations 19.5 and 15.5° N to ∼ 50 m thick at station 11° N. Overall, organic carbon fluxes ranged from 13.2 g m2 yr−1 at 80 m to a minimum of 1.1 g m2 yr−1 at 500 m. Fluxes at the more oxygenated 11° N station attenuate faster than within the permanent ODZ. Martin curve attenuation coefficients for 19.5 and 15.5° N are respectively 0.59 and 0.63 and for 11° N it is 0.98. At least six potential mechanisms might explain why particles sinking through the ODZ are more effectively transferred to depth: (M1) oxygen effects, (M2) microbial loop efficiencies and chemoautotrophy, (M3) changes in zooplankton dynamics, (M4) additions of ballast that might sorb and protect organic matter from decay (M4a) or change sinking speeds (M4b), (M5) inputs of refractory organic matter and (M6) temperature effects. These mechanisms are intertwined, and they were explored using a combination of mineral (XPS) and organic matter characterizations of the sinking material, shipboard incubation experiments, and evaluations of existing literature. Direct evidence was found supporting an oxygen effect and/or changes in the efficiency of the microbial loop including the addition of chemoautotrophic carbon to the sinking flux in the upper 500 m. Less direct evidence was found for the other potential mechanisms. A simple conceptual model consistent with our and other recent data suggests that the upper ODZ microbial community determines the initial flux attenuation, and that zooplankton and sinking speed become more important deeper in the water column. The exact interplay between the various mechanisms remains to be further evaluated.
39
Davenport, John. "Observations on swimming, posture and buoyancy in the giant oceanic ostracods, Gigantocypris mulleri and Macrocypridina castanea." Journal of the Marine Biological Association of the United Kingdom 70, no. 1 (February 1990): 43–55. http://dx.doi.org/10.1017/s0025315400034184.
Повний текст джерелаАнотація:
Gigantocypris is a good swimmer, capable of moving fast enough to overtake a variety of zooplanktonic Crustacea and chaetognaths. It swims smoothly without violent accelerations and decelerations. Previous reports of unstable weak swimming in this species stem from the study of overheated animals; Gigantocypris is stenothermal, adversely affected at temperatures above about 15°C. Gigantocypris is nearly neutrally buoyant (sinking speed 0·2 mm s−1) and is capable of hovering for long periods with the aid of slight movements of the propulsive antennae. When swimming quickly Gigantocypris achieves an average speed of 164 mm s−1 (9·6 mm body length; 391 antennal beats min−1) at 12·5°C. It is unlikely that Gigantocypris performs significant diurnal vertical migrations. The heart of Gigantocypris is large and beats at ca 100 beats min−1. Macrocypridina is a faster swimmer (<52·3 mm s−1 (8·3 mm body length) at 12·5°C with an antennal frequency of 583 beats s−1), but each beat is accompanied by great accelerations and decelerations. Macrocypridina is dense, sinking at 40 mm s−1. Macrocypridina is eurythermal, its swimming speed increasing steadily between 11·5 and 20°C.
40
Loh, Chee Siong, Hiroshi Yokoi, and Tamio Arai. "Natural Heat-Sinking Control Method for High-Speed Actuation of the SMA." International Journal of Advanced Robotic Systems 3, no. 4 (December 2006): 42. http://dx.doi.org/10.5772/5725.
Повний текст джерела
41
LEE, Minju, Seoyeoung JO, and Jihoon LEE. "Analysis for the sinking speed of purse seine using a simulation method." Journal of the Fishing Technology Institute 10, no. 1 (February 28, 2017): 78–91. http://dx.doi.org/10.15399/jfti.2017.02.10.1.78.
Повний текст джерела
42
Lindhe-Norberg, U. M., A. P. Brooke, and W. J. Trewhella. "Soaring and non-soaring bats of the family pteropodidae (flying foxes, Pteropus spp.): wing morphology and flight performance." Journal of Experimental Biology 203, no. 3 (February 1, 2000): 651–64. http://dx.doi.org/10.1242/jeb.203.3.651.
Повний текст джерелаАнотація:
On oceanic islands, some large diurnal megachiropteran bat species (flying foxes; Pteropus spp.) frequently use thermal or slope soaring during foraging flights to save energy. We compared the flight morphology and gliding/soaring performance of soaring versus non-soaring Pteropus species, one pair on American Samoa and one pair on the Comoro Islands, and two other soaring/flap-gliding species and one non-soaring species. We predicted that the soaring species should have a lower body mass, longer wings and, hence, lower wing loadings than those species that use mainly flapping flight. This would give a lower sinking speed during gliding, a higher glide ratio, and enable the bats to make tighter turns with lower sinking speeds than in the non-soaring species. We theoretically calculated the gliding and circling performances of both the soaring and non-soaring species. Our results show that there are tendencies towards longer wings and lower wing loadings in relation to body size in the gliding/soaring flying foxes than in the non-soaring ones. In the species-pair comparison of the soaring and non-soaring species on American Samoa and the Comoro Islands, the soarers on both islands turn out to have lower wing loadings than their non-soaring partners in spite of opposite size differences among the pairs. These characteristics are in accordance with our hypothesis on morphological adaptations. Most differences are, however, only significant at a level of P<0.1, which may be due to the small sample size, but overlap also occurs. Therefore, we must conclude that wing morphology does not seem to be a limiting factor preventing the non-soarers from soaring. Instead, diurnality in the soaring species seems to be the ultimate determinant of soaring behaviour. The morphological differences cause visible differences in soaring and gliding performance. The glider/soarers turn out to have lower minimum sinking speeds, lower best glide speeds and smaller turning radii than the non-soarers. When the wing measurements and soaring performance are normalized to a body mass of 0.5 kg for all species, the minimum sinking speed becomes significantly lower (P<0.05) in the three soaring and the one flap-gliding species (0.63 m s(−)(1)) than in the three non-soaring species (0.69 m s(−)(1)). Interestingly, the zones in the diagrams for the glide polars and circling envelopes of these similar-sized bats become displaced for the glider/soarers versus the non-soarers. The glide polars overlap slightly only at the gliding speeds appropriate for these bats, whereas the circling envelopes do not overlap at the appropriate bank angles and turning radii. This points towards adaptations for better gliding/soaring performance in the soaring and gliding species.
43
Zhu, Qi Dan, Xue Meng, and Zhi Zhang. "Simulation Research on Motion Law of Arresting Hook during Landing." Applied Mechanics and Materials 300-301 (February 2013): 997–1002. http://dx.doi.org/10.4028/www.scientific.net/amm.300-301.997.
Повний текст джерелаАнотація:
The key of a safety landing is the arresting hook can engage an arresting wire. Thus, research on motion law of arresting hook during landing is essential. The construction features and function of typical arresting hook installation is studied. Take into consideration the influence on collision process produced by the deck friction in order to build an actual model of arresting hook during landing. So we can use the model to study the motion law of arresting hook during landing for the sake of supplying a beneficial reference to design of arresting hook and successful engagement with an arresting wire. Simulation results show that the value of height of first hook bounce diminishes linearly with increasing values of coefficient of friction and increases linearly with increasing values of sinking speed. Therefore, we should consider the deck friction in an arresting hook collision which is available for designing a reasonable damper and must ensure the value of sinking speed in a reasonable range to satisfy the condition of engagement with arresting gear.
44
Čížková, Hana, Arie P. van den Berg, Wim Spakman, and Ctirad Matyska. "The viscosity of Earth’s lower mantle inferred from sinking speed of subducted lithosphere." Physics of the Earth and Planetary Interiors 200-201 (June 2012): 56–62. http://dx.doi.org/10.1016/j.pepi.2012.02.010.
Повний текст джерела
45
Dong, Hang, Yonghong Liu, Ming Li, Tong Liu, Yu Zhou, Dege Li, and Yang Shen. "High-speed compound sinking machining of Inconel 718 using water in oil nanoemulsion." Journal of Materials Processing Technology 274 (December 2019): 116271. http://dx.doi.org/10.1016/j.jmatprotec.2019.116271.
Повний текст джерела
46
Fancy, S. G., and R. G. White. "Energy expenditures for locomotion by barren-ground caribou." Canadian Journal of Zoology 65, no. 1 (January 1, 1987): 122–28. http://dx.doi.org/10.1139/z87-018.
Повний текст джерелаАнотація:
Energy expenditure during locomotion on a level treadmill, up and down slopes, and in snow was measured for barren-ground caribou (Rangifer tarandus granti) and compared with that of other species and other subspecies of Rangifer. Highly significant (p < 0.001) linear relationships between [Formula: see text] and walking speed were found for all caribou, indicating that the net cost of walking a given distance was independent of walking speed. The net cost of locomotion (i.e., additional to the cost of standing) for six barren-ground caribou (0.068–0.095 mL O2/(g∙km)) was the lowest of any terrestrial species studied. The mean cost of lifting 1 kg of body weight 1 vertical m was 23 kJ/(g∙m) for slope angles of 4.9 to 6.0°. Caribou recovered 6 kJ/(g∙m) during descent for an average efficiency of 62%. The net cost of locomotion in snow increased exponentially with sinking depth. Energy costs of locomotion in crusted snow were often much higher than those in uncrusted snow in which sinking depth was similar. Brisket height, as an index of leg length, was superior to body weight as a predictor of energy costs of walking for a given individual.
47
Kriest, I., and A. Oschlies. "MOPS-1.0: towards a model for the regulation of the global oceanic nitrogen budget by marine biogeochemical processes." Geoscientific Model Development 8, no. 9 (September 23, 2015): 2929–57. http://dx.doi.org/10.5194/gmd-8-2929-2015.
Повний текст джерелаАнотація:
Abstract. Global models of the oceanic nitrogen cycle are subject to many uncertainties regarding the representation of the relevant biogeochemical processes and of the feedbacks between nitrogen sources and sinks that determine space- and timescales on which the global nitrogen budget is regulated. We investigate these aspects using a global model of ocean biogeochemistry that explicitly considers phosphorus and nitrogen, including pelagic denitrification and nitrogen fixation as sink and source terms of fixed nitrogen, respectively. The model explores different parameterizations of organic matter sinking speed, oxidant affinity of oxic and suboxic remineralization, and regulation of nitrogen fixation by temperature and different stoichiometric ratios. Examination of the initial transient behavior of different model setups initialized from observed biogeochemical tracer distributions reveal changes in simulated nitrogen inventories and fluxes particularly during the first centuries. Millennial timescales have to be resolved in order to bring all biogeochemical and physical processes into a dynamically consistent steady state. Analysis of global properties suggests that not only particularly particle sinking speed but also the parameterization of denitrification determine the extent of oxygen minimum zones, global nitrogen fluxes, and hence the oceanic nitrogen inventory. However, the ways and directions in which different parameterizations of particle sinking, nitrogen fixation, and denitrification affect the global diagnostics are different suggesting that these may, in principle, be constrained independently from each other. Analysis of the model misfit with respect to observed biogeochemical tracer distributions and fluxes suggests a particle flux profile close to the one suggested by Martin et al. (1987). Simulated pelagic denitrification best agrees with the lower values between 59 and 84 Tg N yr−1 recently estimated by other authors.
48
Kriest, I., and A. Oschlies. "MOPS-1.0: modelling the regulation of the global oceanic nitrogen budget by marine biogeochemical processes." Geoscientific Model Development Discussions 8, no. 2 (February 24, 2015): 1945–2010. http://dx.doi.org/10.5194/gmdd-8-1945-2015.
Повний текст джерелаАнотація:
Abstract. Global models of the oceanic nitrogen cycle are subject to many uncertainties, among them type and form of biogeochemical processes involved in the fixed nitrogen cycle, and the spatial and temporal scales, on which the global nitrogen budget is regulated. We investigate these aspects using a global model of ocean biogeochemistry, that explicitly considers phosphorus and nitrogen, including pelagic denitrification and nitrogen fixation as sink and source terms of fixed nitrogen, respectively. The model explores different parameterizations of organic matter sinking speed, oxidant affinity of oxic and suboxic remineralization, and regulation of nitrogen fixation by temperature and different stoichiometric ratios. Examination of the initial transient behaviour of different model setups initialized from observed tracer distributions reveal changes in simulated nitrogen inventories and fluxes particularly during the first centuries. Millennial timescales have to be resolved in order to bring all biogeochemical and physical processes into a dynamically consistent steady state, for which global patterns of biogeochemical tracers and fluxes are reproduced quite well. Analysis of global properties suggests that particularly particle sinking speed, but also the parameterization of denitrification determines the extent of oxygen minimum zones, global nitrogen fluxes, and hence the oceanic nitrogen inventory. However, the ways and directions, in which different parameterizations of particle sinking, nitrogen fixation and denitrification affect the global diagnostics, are different, suggesting that these may, in principle, be constrained independently from each other. Analysis of the model misfit suggests a particle flux profile close to the one suggested by Martin et al. (1987). Simulated pelagic denitrification best agrees with the lower values between 59 and 84 Tg N yr−1 recently estimated by other authors.
49
Sayol, Juan-Manuel, Henk Dijkstra, and Caroline Katsman. "Seasonal and regional variations of sinking in the subpolar North Atlantic from a high-resolution ocean model." Ocean Science 15, no. 4 (August 2, 2019): 1033–53. http://dx.doi.org/10.5194/os-15-1033-2019.
Повний текст джерелаАнотація:
Abstract. Previous studies have indicated that most of the net sinking associated with the downward branch of the Atlantic Meridional Overturning Circulation (AMOC) must occur near the subpolar North Atlantic boundaries. In this work we have used monthly mean fields of a high-resolution ocean model (0.1∘ at the Equator) to quantify this sinking. To this end we have calculated the Eulerian net vertical transport (W∑) from the modeled vertical velocities, its seasonal variability, and its spatial distribution under repeated climatological atmospheric forcing conditions. Based on this simulation, we find that for the whole subpolar North Atlantic W∑ peaks at about −14 Sv at a depth of 1139 m, matching both the mean depth and the magnitude of the meridional transport of the AMOC at 45∘ N. It displays a seasonal variability of around 10 Sv. Three sinking regimes are identified according to the characteristics of the accumulated W∑ with respect to the distance to the shelf: one within the first 90 km and onto the bathymetric slope at around the peak of the boundary current speed (regime I), the second between 90 and 250 km covering the remainder of the shelf where mesoscale eddies exchange properties (momentum, heat, mass) between the interior and the boundary (regime II), and the third at larger distances from the shelf where W∑ is mostly driven by the ocean's interior eddies (regime III). Regimes I and II accumulate ∼90 % of the total sinking and display smaller seasonal changes and spatial variability than regime III. We find that such a distinction in regimes is also useful to describe the characteristics of W∑ in marginal seas located far from the overflow areas, although the regime boundaries can shift a few tens of kilometers inshore or offshore depending on the bathymetric slope and shelf width of each marginal sea. The largest contributions to the sinking come from the Labrador Sea, the Newfoundland region, and the overflow regions. The magnitude, seasonal variability, and depth at which W∑ peaks vary for each region, thus revealing a complex picture of sinking in the subpolar North Atlantic.
50
Zhang, Qi Sheng, Ming Deng, Qi Wang, Yong Qiang Feng, and Rui Yang. "Dynamic Data Transmission Technique for Expendable Current Profiler." Advanced Materials Research 219-220 (March 2011): 436–40. http://dx.doi.org/10.4028/www.scientific.net/amr.219-220.436.
Повний текст джерелаАнотація:
As an expendable profiler in marine environment, XCP (Expendable Current Profiler) is mainly to measure current speed, direction and temperature. The paper is to research dynamic sinking data transmission technique for XCP. Data transmission medium is a varnished wire with diameter of 0.1mm, length of 1,800m and two parallel wires. Transmission characteristics of varnished wires can be tested by experiment and computation. The paper is to research and design a kind of base band transmission system and analyze its characteristics and performance. By utilizing digital base band signaling transmission technique, indoor and marine testing results show that designed data transmission system can reach 1,800m on varnished wires with diameter of 0.1mm if XCP probe sinks dynamically by speed of 4m/s and transmission speed is 2,400bps.