Average energy density and the size of the Universe

1987 ◽  
Vol 36 (8) ◽  
pp. 2226-2228 ◽  
Author(s):  
Niall O’Murchadha
Keyword(s):  
Energy Density ◽  
Average Energy ◽  
Average Energy Density ◽  
The Universe

Macroscale bending large-deformation and microbuckling behavior of a unidirectional fiber-reinforced soft composite

2019 ◽  
Vol 54 (2) ◽  
pp. 243-257
Author(s):  
Xin Lan ◽  
Sida Hao ◽  
Liwu Liu ◽  
Yanju Liu ◽  
Jinsong Leng
Keyword(s):  
Partial Differential Equations ◽  
Energy Density ◽  
Numerical Method ◽  
Large Deformation ◽  
Deformation Behavior ◽  
Average Energy ◽  
Theoretical Method ◽  
Fiber Reinforced ◽  
Average Energy Density ◽  
Soft Composite

Due to microscale fiber microbuckling, a fiber-reinforced soft composite demonstrates large macroscale bending deformation (e.g. 10% reversible macroscale compressive strain), which is larger than that of a convenient fiber-reinforced plastics (e.g. 1.5–2% elongation/compression at break). To investigate the deformation behavior, a normalized average energy density of a fiber-reinforced soft composite laminate was derived. By using a self-consistent approach according to the minimum energy principle, a series of analytical expressions were derived by a simplified theoretical method through solving simplified partial differential equations of average energy density. Furthermore, an improved numerical calculation method was developed using the full four terms of partial differential equations of average energy density by employing the results of simplified theoretical method as initial calculating values. The dimensionless results demonstrated that the trend correlated well between those two methods, and the improved numerical method obtained more accurate results than those of the simplified theoretical method. Analytical and numerical results in normalized expressions systematically descripted the bending large-deformation behavior including position of neutral surface and critical buckling, wavelength, amplitude, shearing strain, macroscale compressive/tensile strain, buckled fiber strain, and actuation moment. To design a fiber-reinforced soft composite for use in engineering, the simplified theoretical method is used to predict trend and obtain approximate results for preliminary design, and the improved numerical method is further used to check and obtain more accurate results on detailed design stage.

scholarly journals About the Origin of the Dark Energy and the Zero Mass/Energy Universe

2021 ◽  
pp. 1-7
Author(s):  
Guenter Frohberg
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Total Energy ◽  
Average Energy ◽  
Friedmann Equation ◽  
Relativity Theory ◽  
Total Energy Density ◽  
Gravitational Fields ◽  
Expansion Of The Universe ◽  
The Universe

Based on the Gravito-Electro-Magnetic (GEM) equations as another form (for low fields) of Einstein's Equations of General Relativity Theory (GRT) an equation is derived for the total energy density in the universe, including the gravitational fields, the contribution thereof is always negative and so it seems to represents the Dark Energy (DE).  When calculating the total energy of the universe from this equation, the result is near to zero because of negative contributions from gravitational fields, depending a little on the available parameters of the universe as e.g. it's baryonic mass. Thus the assumption is given a high amount of probability, that the total energy (mass) in the universe is really zero and very likely is always zero. This  would mean, that the universe developed from empty space-time or from nothing (may be by quantum fluctuations). Looking on the development it could be  that the average energy density is zero for each sufficient large part of the universe at any time, except for very local deviations (e.g. galaxies, black holes etc.). As a consequence the expansion of the universe is probably not retarded by gravity (thus the Friedmann equation and others do not apply). The expansion of the universe can be considered as driven by the pressure of a gas-like medium with positive masses as by intergalactic gas, dust, stars and galaxies. Conclusions are drawn as to the interpretation of the formation of voids in the universe, flat space etc.

scholarly journals ANOMALOUS MODULATION OF THE WAVE FIELD IN A PLASMA WAVEGUIDE

2019 ◽  
pp. 111-114
Author(s):  
V.M. Kuklin ◽  
E.V. Poklonskiy
Keyword(s):  
Energy Density ◽  
Wave Field ◽  
Modulation Instability ◽  
Average Energy ◽  
Plasma Waveguide ◽  
Frequency Of Occurrence ◽  
Average Amplitude ◽  
Weak Absorption ◽  
Average Energy Density

The consequences of the development of the modulation instability of an intense wave field in a waveguide filled with plasma are considered. It is shown that in the mode of developed instability, the amplitude of the main wave under conditions of its weak absorption decreases by three to four times. The average energy density of the instability spectrum is almost twice the energy density of the main wave. The amplitude of the modulation envelope is three times the average amplitude of the main wave. The frequency of occurrence of anomalous modulation bursts is estimated.

Duration of lactation and postweaning changes in mass and body composition of harbour seal, Phoca vitulina, pups

1993 ◽  
Vol 71 (7) ◽  
pp. 1405-1414 ◽  
Author(s):  
M. M. C. Muelbert ◽  
W. D. Bowen
Keyword(s):  
Body Composition ◽  
Energy Density ◽  
Mass Loss ◽  
Body Mass ◽  
Deuterium Oxide ◽  
Average Energy ◽  
Phoca Vitulina ◽  
Low Energy ◽  
Harbour Seal ◽  
Average Energy Density

We studied changes in body mass and body composition of harbour seal pups from weaning to 5 – 6 weeks postweaning in June – August 1988 and 1989 on Sable Island, Canada. Known-age pups (n = 52) were captured at 3-day intervals from late lactation through about 40 days postweaning. Pups were weaned, on average, at 24.1 ± 0.44 days (mean ± SE) postpartum at a body mass of 24.9 ± 0.45 kg. There were no significant differences between years or sexes in the age and mass at weaning or in the rate of mass loss during the postweaning period. The duration of the postweaning fast averaged from 15 – 17 days as assessed by stomach lavage. The rate of mass loss was independent of weaning mass. At weaning, pups contained an average of 47.7% water and 32.8% fat, based on deuterium oxide dilution. During the first 14 days postweaning, the estimated body composition of pups did not change, despite the loss of body mass. Over the next 26 days, the estimated percent body water increased to about 63% and body fat declined to about 12%. The average energy density of harbour seal pups at weaning was low (16.3 kJ/g) compared with that of other phocids (17.7 – 22.2 kJ/g). This low energy density at weaning may reflect the highly aquatic and precocial development of harbour seal pups.

scholarly journals Energy Density and Satiety of Meals Based on the Healthy Food Plate Model for Filipino Adults

2018 ◽  
Vol 52 (6) ◽  
Author(s):  
Maria Julia Golloso-Gubat ◽  
Edward Vincent J. Magtibay ◽  
Jacus S. Nacis ◽  
Robby Carlo A. Tan ◽  
Merlyn G. Tajan ◽  
...  
Keyword(s):  
Energy Density ◽  
Healthy Adult ◽  
Average Energy ◽  
Healthy Food ◽  
Low Energy ◽  
Plate Model ◽  
Short Term ◽  
Average Energy Density ◽  
Adult Volunteers ◽  
Analogue Scales

Objective. This study aimed to determine the energy density and satiety of meals based on the healthy food plate model for Filipino adults. Methods. Thirteen healthy adult volunteers consumed breakfast test meals consisting of 1 cup go food, ½ cup grow food and 1 ½ cups glow food, following the recommended proportions in the plate model. Energy density (kcal/g) of the test meals was calculated. Feelings of hunger and fullness were assessed with 100-mm visual analogue scales (VAS) at pre-prandial (0 minute) and at 30, 60, 90, 120, 150, 180, and 240 minutes postprandial. Ghrelin levels at 0, 30, 60, 120, 180, and 240 minutes were determined by radioimmunoassay (RIA). Results. The test meals had an average energy density of 0.83 kcal/g. Hunger and fullness scores gradually changed with time but hunger remained significantly lower and fullness significantly higher than the pre-prandial levels at 180 minutes postprandial. Ghrelin declined after intake of the test meals and stayed significantly lower than the pre-prandial level at 240 minutes postprandial (30.21 ± 4.58 pmol/L). Conclusion. Meals following the recommendations in the healthy food plate model for Filipino adults have low energy density and its consumption sustained short-term satiety.

scholarly journals Rechargeable Concrete Battery

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 103
Author(s):  
Emma Qingnan Zhang ◽  
Luping Tang
Keyword(s):  
Energy Density ◽  
Carbon Fibers ◽  
Average Energy ◽  
Metal Coating ◽  
Rechargeable Battery ◽  
Powder Mixing ◽  
Coating Method ◽  
Average Energy Density ◽  
Short Carbon ◽  
Charge Discharge

A rechargeable cement-based battery was developed, with an average energy density of 7 Wh/m2 (or 0.8 Wh/L) during six charge/discharge cycles. Iron (Fe) and zinc (Zn) were selected as anodes, and nickel-based (Ni) oxides as cathodes. The conductivity of cement-based electrolytes was modified by adding short carbon fibers (CF). The cement-based electrodes were produced by two methods: powder-mixing and metal-coating. Different combinations of cells were tested. The results showed that the best performance of the rechargeable battery was the Ni–Fe battery, produced by the metal-coating method.

scholarly journals Dynamical system analysis of FLRW models with Modified Chaplygin gas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Osman Yılmaz ◽  
Ertan Güdekli
Keyword(s):  
Dynamical System ◽  
Equation Of State ◽  
Energy Density ◽  
System Analysis ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
State Spaces ◽  
The Universe ◽  
Matter Energy ◽  
Far Future

AbstractWe investigate Friedmann–Lamaitre–Robertson–Walker (FLRW) models with modified Chaplygin gas and cosmological constant, using dynamical system methods. We assume $$p=(\gamma -1)\mu -\dfrac{A}{\mu ^\alpha }$$ p = ( γ - 1 ) μ - A μ α as equation of state where $$\mu$$ μ is the matter-energy density, p is the pressure, $$\alpha$$ α is a parameter which can take on values $$0<\alpha \le 1$$ 0 < α ≤ 1 as well as A and $$\gamma$$ γ are positive constants. We draw the state spaces and analyze the nature of the singularity at the beginning, as well as the fate of the universe in the far future. In particular, we address the question whether there is a solution which is stable for all the cases.

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