Costs of transport for the scyphomedusa Stomolophus meleagris L. Agassiz

1987 ◽  
Vol 65 (11) ◽  
pp. 2690-2695 ◽  
Author(s):  
R. J. Larson

The rhizostome scyphomedusa Stomolophus meleagris swims continuously at speeds up to 15 cm∙s−1. Mean velocities increased as a power function of wet weight up to 70 g but were mostly constant thereafter. Bell pulsations ranged from 1.7 to 3.6 Hz. Reynolds numbers equalled 900 – 13 000. During activity, medusae consumed 0.05 mL O2∙h−1∙g WW−1 (1.2 mL O2∙h−1∙g DW−1), at 30 °C. Rates for inactive medusae were 50% less. The estimated cost of transport ranged from 2 J∙kg−1∙m−1 at 5 g to 1 J∙kg−1∙m−1 at 1 kg. These rates are comparable to those of fishes and about 1/50th that of planktonic crustaceans. These results were unexpected in light of the typical inefficiency (power output/power input) of jet swimming. However, S. meleagris has a very low respiration rate relative to crustaceans and fish, which probably compensated for low swimming efficiency.

2021 ◽  
Vol 31 (1) ◽  
pp. 27-39
Author(s):  
Essa Ibrahim Essa ◽  
Mshari A. Asker ◽  
Fidan T. Sedeeq

Abstract Using optical add–drop multiplexer/remover multiplexer (OADM), it is possible to add or remove wavelengths and change or route them through the various nodes and networks. At this moment, key problems in add–drop multiplexer (ADM) are the bandwidth, modulation format, and reuse wavelength. In this article, the Optisystem software simulation is used as a platform to design, test, and verify the method applied to the current work; the OADM is proposed based on the metro network to get distribution between nodes over a transmission link; OADM analysis was presented with four channels (193.1, 193.2, 193.3, and 193.4 THz) at total bandwidth of 1.6 Tb/s, none-return-to-zero (NRZ), and return to zero coding types. Experiment one shows that the average output power is −17.997 dBm, the average drop power is −17.997 dBm, and the average add power is −18.338 dBm, the average gain is −0.0429 dB, the average noise figure is 0 dB, the average power input signal is 10.679 dBm, the average of power output signal is 10.633 dBm, and the average output optical signal-to-noise ratio (OSNR) is 0 dB, However, the second experiment shows that the average output power is −24.238 dBm, the average drop power is −24.288 dBm, and the average add power is −24.753 dBm, the average gain is −0.0417 dB, the average noise figure is 0 dB, average power input signal is 7.691 dBm, average of power output signal is 7.677 dBm, and the average output OSNR 0 dB. The system supports four input channels, four add channels, four output channels, and four drop channels. The results are acceptable after three spans of Solitons fiber with 600 km length, 200 km for each span. Nonetheless, it is believed that it is well justified to adopt these schemes in the current optical network with a low cost for overall expenditure.


1997 ◽  
Vol 200 (7) ◽  
pp. 1133-1143 ◽  
Author(s):  
F O Lehmann ◽  
M H Dickinson

The limits of flight performance have been estimated in tethered Drosophila melanogaster by modulating power requirements in a 'virtual reality' flight arena. At peak capacity, the flight muscles can sustain a mechanical power output of nearly 80 W kg-1 muscle mass at 24 degrees C, which is sufficient to generate forces of approximately 150% of the animal's weight. The increase in flight force above that required to support body weight is accompanied by a rise in wing velocity, brought about by an increase in stroke amplitude and a decrease in stroke frequency. Inertial costs, although greater than either profile or induced power, would be minimal with even modest amounts of elastic storage, and total mechanical power energy should be equivalent to aerodynamic power alone. Because of the large profile drag expected at low Reynolds numbers, the profile power was approximately twice the induced power at all levels of force generation. Thus, it is the cost of overcoming drag, and not the production of lift, that is the primary requirement for flight in Drosophila melanogaster. By comparing the estimated mechanical power output with respirometrically measured total power input, we determined that muscle efficiency rises with increasing force production to a maximum of 10%. This change in efficiency may reflect either increased crossbridge activation or a favorable strain regime during the production of peak forces.


2018 ◽  
Vol 8 (2) ◽  
Author(s):  
I.W. Joniarta ◽  
M. Wijana ◽  
A.A. Alit Triadi ◽  
I.B.K.T.H. Iswara ◽  
I.G.A.K.C. Adhi

Agricultural waste such as corn cobs and coconut shell can be used as alternative energy. Biomass as an alternative energy can be used as a fuel in the furnace. Corncob has low calorific value and density, so it is necessary to examine the combination’s effect of corn cobs and coconut shell toward the performances of biomass furnace.The gasification furnace was the development of a furnace design on previous research. Diameter of combustion chamber is 25 cm, diameter of free air duct and secondary air duct is 2 cm, and primary air duct is 1 cm. Combined corncob and coconut shell in sequence are 100%: 0%, 80%: 20%, 60%: 40%, 40%: 60%, 20%: 80%, 0%: 100%. Investigated parameters showing the furnace performance were boiling time, FCR, power input, power output, power loss and efficiency are boiling time, FCR, operating time, power input, power output, power loss and efficiency. Test of operating time were conducted by burning fuel until burned out. Then boiling time test were conducted by heated 1 liters water from ambient temperature to boiling (between 95oC - 97oC) on a 24 cm diameter pan.The results showed that the largest operating time (1317.33 Seconds), smallest FCR (2.249 Kg/hour), smallest power loss (19.532 kW), and the highest efficiency (8.19%) obtained at 0% : 100% combination. The fastest boiling time (157 Seconds) and the largest power output (1.828 kW) was obtained at 40%: 60% combination. While the largest power input (29.286 kW) was obtained at 60%: 40%.


2019 ◽  
Vol 18 (3) ◽  
pp. 118
Author(s):  
Anderson Pontes Morales ◽  
Felipe Sampaio-Jorge ◽  
Thiago Barth ◽  
Alessandra Alegre De Matos ◽  
Luiz Felipe Da Cruz Rangel ◽  
...  

Introduction: The aim of this study was to test the hypothesis that caffeine supplementation (6 mg·kg-1 body mass) for 4-days, followed by acute intake, would impact five male triathletes output power after performed submaximal intensity exercise. Methods: This was a randomized, double-blind, placebo-controlled crossover study, placebo (4-day) - placebo (acute) PP, placebo (4-days) -caffeine (acute) PC, and caffeine (4-day) - caffeine (acute) CC. Participants abstained from dietary caffeine sources for 4 days and ingested capsules containing either placebo or caffeine (6 mg.kg-1 body mass day in one absorption). The acute trials the capsules containing placebo or caffeine (6 mg.kg-1 body mass day in one absorption) were ingested 60min before completing exercise in a treadmill for 40min (80% VO2max) and to perform the Wingate test. Results: Blood lactate was determined before, 60min after ingestion, and immediately after the exercise on the treadmill, the Wingate test, and after the recovery (10-min). CC and PC trials did not change the cardiopulmonary variables (P>0.05) and the anaerobic power variables (peak/mean power output and fatigue index) (P>0.05). The PC trial compared with PP promoted improvements in the curve power output in 2 sec by 31.19% (large effect-size d = 1.08; P<0.05) and 3 sec by 20% (large effect-size d = 1.19; P<0.05). A 10min recovery was not sufficient to reduce blood lactate concentration in the PC trial compared with PP (PC, 13.73±2.66 vs. PP, 10.26±1.60 mmol.L-1; P<0.05, respectively) (P<0.05). Conclusion: In conclusion, these results indicate that caffeine supplementation (6 mg·kg-1 body mass) for 4 days, followed by acute ingestion, did not impact the triathletes output power after performed submaximal intensity exercise. Nutritional interventions may help researchers and athletes to adapt strategies for manipulating caffeine use.Key-words: caffeine metabolism, Wingate test, blood lactate, performance.


Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3861
Author(s):  
Jie Mei ◽  
Qiong Fan ◽  
Lijie Li ◽  
Dingfang Chen ◽  
Lin Xu ◽  
...  

With the rapid development of wearable electronics, novel power solutions are required to adapt to flexible surfaces for widespread applications, thus flexible energy harvesters have been extensively studied for their flexibility and stretchability. However, poor power output and insufficient sensitivity to environmental changes limit its widespread application in engineering practice. A doubly clamped flexible piezoelectric energy harvester (FPEH) with axial excitation is therefore proposed for higher power output in a low-frequency vibration environment. Combining the Euler–Bernoulli beam theory and the D’Alembert principle, the differential dynamic equation of the doubly clamped energy harvester is derived, in which the excitation mode of axial load with pre-deformation is considered. A numerical solution of voltage amplitude and average power is obtained using the Rayleigh–Ritz method. Output power of 22.5 μW at 27.1 Hz, with the optimal load resistance being 1 MΩ, is determined by the frequency sweeping analysis. In order to power electronic devices, the converted alternating electric energy should be rectified into direct current energy. By connecting to the MDA2500 standard rectified electric bridge, a rectified DC output voltage across the 1 MΩ load resistor is characterized to be 2.39 V. For further validation of the mechanical-electrical dynamical model of the doubly clamped flexible piezoelectric energy harvester, its output performances, including both its frequency response and resistance load matching performances, are experimentally characterized. From the experimental results, the maximum output power is 1.38 μW, with a load resistance of 5.7 MΩ at 27 Hz, and the rectified DC output voltage reaches 1.84 V, which shows coincidence with simulation results and is proved to be sufficient for powering LED electronics.


2015 ◽  
Vol 66 (10) ◽  
pp. 857 ◽  
Author(s):  
James Prescott ◽  
Shijie Zhou ◽  
Andhika P. Prasetyo

Tropical sea cucumbers are commonly exploited by small-scale, poorly managed fisheries. A fundamental problem in managing sea cucumber fisheries is the lack of basic knowledge of important life history characteristics for most species. As a result of plastic body dimensions, biological research on this group of animals becomes exceptionally challenging. To improve our understanding of essential biological parameters, we conducted a study to investigate correlations among various body measurements. We analysed a total of 18 sea cucumber species and more than 6600 individuals collected at Scott Reef in the Timor Sea, north-west Australia. We used hierarchical Bayesian errors-in-variables models to specifically take into account measurement errors that are obviously unavoidable. The measures included three types of weights (wet weight, gutted weight and dry weight) and two body dimensions (length and width). The modelling reveals that using both body length and width as independent variables, wet weight increases approximately linearly with body length, but is a power function (~1.6) of body width, although variability exists among species. Dry weight tends to increase more slowly with body length, but has a similar power function of body width. Linear relationships are established between the three types of weights. On average, ~11% of a live specimen and ~16% of a gutted specimen is processed to the commercially traded dry body wall. Our results can be applied to sea cucumbers in other areas and can be useful for data standardisation and size-based fisheries management.


1987 ◽  
Vol 131 (1) ◽  
pp. 137-157
Author(s):  
D. F. HOULIHAN ◽  
C. AGNISOLA ◽  
N. M. HAMILTON ◽  
I. TRARA GENOINO

A technique is described which allowed the measurement of the oxygen consumption of the isolated heart of Octopus vulgaris. Contraction of the heart resulted in an aortic output and a flow through the heart muscle into coronary veins (the coronary output). The flow and oxygen content of the aortic output and the coronary output were measured with variable input pressures and constant output back pressure (volume loaded), variable output back pressure and constant aortic output (pressure loaded), and during hypoxia. Volume loading of the heart resulted in an increase in aortic output, power output and total oxygen consumption. Pressure loading increased power output and total oxygen consumption of the heart. Exposure to hypoxia decreased the aortic output, power output and total cardiac oxygen consumption. In the response of the heart to reduced work, brought about either by a reduced input pressure or by hypoxic perfusate, the power output was linearly related to the total oxygen consumption of the heart. The oxygen extracted from the coronary output accounted for 80–100% of the total oxygen consumption of the heart. Coronary output amounted to 30% of the total cardiac output at maximum power output. In volume-loaded hearts the volume of the coronary output increased as aortic output increased; in pressure-loaded hearts coronary output increased as power output increased, but aortic output remained constant. In hypoxia, the coronary output increased as the aortic output fell. At a perfusate Po2 of around 50 Torr (1 Torr = 133 Pa), the aortic output ceased although the heart continued to beat and the coronary output continued, accounting for all of the oxygen consumption of the heart. The coronary output flow in vitro therefore has the capacity to be varied independently of the aortic output flow to maintain the oxygen supply to the perfused cardiac muscle.


1995 ◽  
Vol 27 (Supplement) ◽  
pp. S245
Author(s):  
S. M. Puhl ◽  
L. F. Fussner ◽  
J. L. Hodgson ◽  
K. G. Stoedefalke

1991 ◽  
Vol 15 (1) ◽  
pp. 24-37 ◽  
Author(s):  
C. A. McLaurin ◽  
C. E. Brubaker

Wheelchair biomechanics involves the study of how a wheelchair user imparts power to the wheels to achieve mobility. Because a wheelchair can coast, power input need not be continuous, but each power strike can be followed by a period of recovery, with the stroking frequency depending on user preferences and the coasting characteristics of the wheelchair. The latter is described in terms of rolling resistance, wind resistance and the slope of the surface. From these three factors the power required to propel the wheelchair is determined, and must be matched by the power output of the user. The efficiency of propulsion is the ratio of this power output to the metabolic cost and is typically in the order of 5% in normal use. The features required in a wheelchair depend upon user characteristics and intended activities. The ideal wheelchair for an individual will have the features that closely match these characteristics and activities. Thus prescription is not just choosing a wheelchair, but choosing the components of the wheelchair that best serve the intended purpose. In this paper, each component is examined for available options and how these options effect the performance of the wheelchair for the individual. The components include wheels, tyres, castors, frames, bearings, materials, construction details, seats, backrests, armrests, foot and legrests, headrests, wheel locks, running brakes, handrims, levers, accessories, adjustments and detachable parts. Each component is considered in relation to performance characteristics including rolling resistance, versatility, weight, comfort, stability, maneouvrability, transfer, stowage, durability and maintenance. Where they exist, wheelchair standards are referred to as a source of information regarding these characteristics.


2013 ◽  
Vol 336-338 ◽  
pp. 1114-1117 ◽  
Author(s):  
Ying Zhi Liu ◽  
Wen Xia Liu

This paper elaborates the effect of wind speed on the output power of the wind farms at different locations. It also describes the correction of the power curve and shows the comparison chart of the standard power curve and the power curve after correction. In China's inland areas, wind farms altitude are generally higher, the air density is much different from the standard air density. The effect of air density on wind power output must be considered during the wind farm design.


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