A relook at radiation by a point charge. I

Efforts to suggest a classical model for the hydrogen atom are discouraged by a conclusion, based on the principles of electrodynamics, that an accelerating charged particle necessarily radiates. In this paper, we re-examine the steps leading to this conclusion. We start with the relativistic expressions for energy and momentum of a particle and establish the relationship between special relativity and electrodynamics. The standard field expression and its relativistic transformations are then studied for a point charge source, represented by a delta function. In conventional Poynting’s theorem analysis, the rate of change of work done on a system of charges is written as addition of two terms, rate of change of stored energy, and surface integral of Poynting vector. For a delta function source, the first two terms of this equation are either non-integrable or difficult to evaluate. Only the third surface integration term can be evaluated, which is said to give radiation by the point charge. Thus, the statement that an accelerated charge radiates is a conclusion based on this Poynting vector analysis. We examine it and realize that this statement, namely, that a point charge radiates continuously just because it is accelerating, does not have adequate theoretical justification.

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A relook at radiation by a point charge. II

Canadian Journal of Physics ◽

10.1139/cjp-2017-0072 ◽

2017 ◽

Vol 95 (11) ◽

pp. 1150-1160

Author(s):

Nitin Ramchandra Gadre

Keyword(s):

Hydrogen Atom ◽

Poynting Vector ◽

Particle System ◽

Classical Model ◽

Rate Of Change ◽

Circular Orbits ◽

Discrete Energy ◽

Radiation Study ◽

The Given ◽

Classical Picture

Efforts to suggest a classical model for the hydrogen atom are discouraged by a conclusion, based on the principles of electrodynamics, that an accelerating charged particle necessarily radiates. In this paper, we continue our re-examination of this conclusion. We examine the standard electric field formula and difficulties associated with it, for an accelerating source. Conventionally, the Larmor formula is obtained from the Poynting vector. We obtain this Larmor formula by finding rate of change of potential energy in the given volume. We feel that, in this task, the logic is weak and our assumptions are difficult to justify. We have to conclude that the statement, radiation makes classical circular orbits unstable is difficult to justify theoretically. Then circular orbits with all radii, with matching velocities, should be allowed classically. We try to give some justification for Bohr postulates, then only certain radii will be allowed resulting in discrete energy states. We conclude that, for radiation study, it is advisable to calculate change in total energy of the system instead of following a theorem-based approach. We require complete and well defined systems to evolve a classical picture, which makes it desirable to study a simple two-particle system of hydrogen atom.

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Three-dimensional time-harmonic elastodynamic Green ’ s functions for anisotropic solids

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences ◽

10.1098/rspa.1995.0052 ◽

1995 ◽

Vol 449 (1937) ◽

pp. 441-458 ◽

Cited By ~ 102

Keyword(s):

Differential Equations ◽

Radon Transform ◽

Transverse Isotropy ◽

Three Dimensional ◽

Surface Integral ◽

Line Integral ◽

Surface Integration ◽

Time Harmonic ◽

Inverse Radon Transform ◽

Eigenvectors And Eigenvalues

A method based on the Radon transform is presented to determine the displacement field in a general anisotropic solid due to the application of a time-harmonic point force. The Radon transform reduces the system of coupled partial differential equations for the displacement components to a system of coupled ordinary differential equations. This system is reduced to an uncoupled form by the use of properties of eigenvectors and eigenvalues. The resulting simplified system can be solved easily. A back transformation to the original coordinate system and a subsequent application of the inverse Radon transform yields the displacements as a summation of a regular elastodynamic term and a singular static term. Both terms are integrals over a unit sphere. For the regular dynamic term, the surface integration can be evaluated numerically without difficulty. For the singular static term, the surface integral has been reduced to a line integral over half a unit circle. Reductions to the cases of isotropy and transverse isotropy have been worked out in detail. Examples illustrate applications of the method.

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Study of Power Flow in an IPT System Based on Poynting Vector Analysis

Energies ◽

10.3390/en11010165 ◽

2018 ◽

Vol 11 (1) ◽

pp. 165 ◽

Cited By ~ 2

Author(s):

Yuan Liu ◽

Aiguo Hu

Keyword(s):

Output Power ◽

Power Distribution ◽

Power Flow ◽

Poynting Vector ◽

Current Source ◽

Arbitrary Point ◽

Secondary Coil ◽

Surface Integral ◽

Vector Method ◽

Coupled Coils

This paper analyzes the power distribution and flow of an inductive power transfer (IPT) system with two coupled coils by using the Poynting vector. The system is modelled with a current source flowing through the primary coil, and a uniformly loaded secondary first, then the Poynting vector at an arbitrary point is analyzed by calculating the magnetic and electric fields between and around of the two coils. Both analytical analysis and numerical analysis have been undertaken to show the power distribution, and it has found that power distributes as a donut shape in three-dimensional (3D) space and concentrates along the edges in the proposed two-coil setup, instead of locating coaxially along the center path. Furthermore, power flow across the mid-plane between the two coils is analyzed analytically by the surface integral of the Poynting vector, which is compared with the input power from the primary and the output power to the secondary coil via coupled circuit theory. It has shown that for a lossless IPT system, the power transferred across the mid-plane is equal to the input and output power, which validates the Poynting vector approach. The proposed Poynting vector method provides an effective way to analyze the power distribution in the medium between two coupled coils, which cannot be achieved by traditional lumped circuit theories.

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Axisymmetric Hurricane in a Dry Atmosphere: Theoretical Framework and Numerical Experiments

Journal of the Atmospheric Sciences ◽

10.1175/2011jas3639.1 ◽

2011 ◽

Vol 68 (8) ◽

pp. 1607-1619 ◽

Cited By ~ 18

Author(s):

Agnieszka A. Mrowiec ◽

Stephen T. Garner ◽

Olivier M. Pauluis

Keyword(s):

Water Vapor ◽

High Resolution ◽

Numerical Model ◽

Numerical Experiments ◽

Momentum Flux ◽

Theoretical Framework ◽

Moist Processes ◽

Energy And Momentum ◽

The Relationship ◽

Theoretical Insight

Abstract This paper discusses the possible existence of hurricanes in an atmosphere without water vapor and analyzes the dynamic and thermodynamic structures of simulated hurricane-like storms in moist and dry environments. It is first shown that the “potential intensity” theory for axisymmetric hurricanes is directly applicable to the maintenance of a balanced vortex sustained by a combination of surface energy and momentum flux, even in the absence of water vapor. This theoretical insight is confirmed by simulations with a high-resolution numerical model. The same model is then used to compare dry and moist hurricanes. While it is found that both types of storms exhibit many similarities and fit well within the theoretical framework, there are several differences, most notably in the storm inflow and in the relationship between hurricane size and intensity. Such differences indicate that while water vapor is not necessary for the maintenance of hurricane-like vortices, moist processes directly affect the structure of these storms.

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Five Dimensions of Online Persona

Persona Studies ◽

10.21153/ps2017vol3no1art658 ◽

2017 ◽

Vol 3 (1) ◽

pp. 1-12 ◽

Cited By ~ 6

Author(s):

Christopher Moore ◽

Kim Barbour ◽

Katja Lee

Keyword(s):

Digital Media ◽

The Self ◽

First Century ◽

Five Dimensions ◽

The Public ◽

Cultural Paradigm ◽

Online Persona ◽

Work Done ◽

The Relationship ◽

Digital Identities

Before Facebook, Twitter, and most of the digital media platforms that now form routine parts of our online lives, Jay Bolter (2000) anticipated that online activities would reshape how we understand and produce identity: a ‘networked self’, he noted, ‘is displacing Cartesian printed self as a cultural paradigm’ (2000, p. 26). The twenty-first century has not only produced a proliferation and mass popularisation of platforms for the production of public digital identities, but also an explosion of scholarship investigating the relationship between such identities and technology. These approaches have mainly focussed on the relations between humans and their networks of other human connections, often neglecting the broader implications of what personas are and might be, and ignoring the rise of the non-human as part of social networks. In this introductory essay, we seek to both trace the work done so far to explore subjectivity and the public presentation of the self via networked technologies, and contribute to these expanding accounts by providing a brief overview of what we consider to be five important dimensions of an online persona. In the following, we identify and explicate the five dimensions of persona as public, mediatised, performative, collective and having intentional value and, while we acknowledge that these dimensions are not exhaustive or complete, they are certainly primary.

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The theory of the chain fountain revisited

Journal of Physics Conference Series ◽

10.1088/1742-6596/2090/1/012166 ◽

2021 ◽

Vol 2090 (1) ◽

pp. 012166

Author(s):

Dragos-Victor Anghel

Keyword(s):

Energy Transfer ◽

Kinetic Energy ◽

Significant Role ◽

Mechanical Work ◽

Scientific Consensus ◽

Energy And Momentum ◽

Work Done

Abstract We analyze the chain fountain effect-the chain siphoning when falling from a container onto the floor. We argue that the main reason for this effect is the inertia of the chain, whereas the momentum received by the beads of the chain from the bottom of the container (typically called “kicks”) plays no significant role. The inertia of the chain leads to an effect similar to pulling the chain over a pulley placed up in the air, above the container. In another model (the so called “scientific consensus”), it was assumed that up to half of the mechanical work done by the tension in the chain may be wasted when transformed into kinetic energy during the pickup process. This prevented the chain to rise unless the energy transfer in the pickup process is improved by the “kicks” from the bottom of the container. Here we show that the “kicks” are unnecessary and both, energy and momentum are conserved-as they should be, in the absence of dissipation-if one properly considers the tension and the movement of the chain. By doing so, we conclude that the velocity acquired by the chain is high enough to produce the fountain effect. Simple experiments validate our model and certain configurations produce the highest chain fountain, although “kicks” are impossible.

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Hubungan Kecepatan Pendinginan Air dengan Kecepatan Tiupan Udara

Prosiding SNFA (Seminar Nasional Fisika dan Aplikasinya) ◽

10.20961/prosidingsnfa.v2i0.16404 ◽

2017 ◽

Vol 2 ◽

pp. 241

Author(s):

Taat Guswantoro ◽

Manogari Sianturi ◽

Nurafni Prapitasari ◽

Areli Elona

Keyword(s):

Regression Analysis ◽

Wind Speed ◽

Linear Regression ◽

Water Temperature ◽

Rate Of Change ◽

Hot Water ◽

Water Cooling ◽

Exponential Regression ◽

The Relationship

Abstract: In this study hot water was placed in two erlenmeyer scale 100 ml clogged and without plug, each filled with 150 ml hot water and allowed to cool in air. Measurement of water temperature using sensor connected to the interface and recorded using the pasco capstone 14.1. The wind is raised with the fan, to adjust the wind speed by adjusting the fan distance, the speed is measured using an anemometer. The water cooling constant is obtained by a decay exponential regression analysis of temperature vs time. The relationship between water colling coefficient with wind speed is used linear regression. From the research, the water cooling coefficient naturally for clogging erlenmeyer is 3,1 x 10-4 s-1 and for erlenmeyer without plug 3.8 x 10-4 s-1, the rate of change of water cooling constant to wind speed is 1 , 4 x 10-4 m-1. Abstrak: Pada penelitian ini air panas ditempatkan dalam dua buah erlenmeyer berskala 100 ml bersumbat dan tanpa sumbat, masing-masing diisi air panas dengan volume 150 ml dan dibiarkan mendingin di udara. Pengukuran suhu air dengan menggunakan sensor panas yang dihubungkan ke interface dan dicatat menggunakan program pasco capstone 14.1. Angin dibangkitkan dengan kipas, untuk mengatur kecepatan angin dengan cara mengatur jarak kipas, kecepatan angin diukur menggunakan anemometer. Konstanta pendinginan air diperoleh dengan analisis regresi eksponensial meluruh dari data suhu dan waktu. Hubungan antara koefisien pendinginan air dengan kecepatan angin digunakan regresi linier. Dari penelitian diperoleh koefisien pendinginan air secara alami untuk erlenmeyer tersumbat sebesar 3,1 x 10-4 s-1 dan untuk erlenmeyer tanpa sumbat sebesar 3,8 x 10-4 s-1, laju perubahan konstanta pendinginan air terhadap kecepatan angin adalah sebesar 1,4 x 10-4 m-1.

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Influence of muscle length on work from trabecular muscle of frog atrium and ventricle.

Journal of Experimental Biology ◽

10.1242/jeb.198.10.2221 ◽

1995 ◽

Vol 198 (10) ◽

pp. 2221-2227 ◽

Cited By ~ 1

Author(s):

D A Syme ◽

R K Josephson

Keyword(s):

Isometric Force ◽

Muscle Length ◽

Work Capacity ◽

Linear Increase ◽

Ventricular Muscle ◽

Work Output ◽

Loop Technique ◽

Work Done ◽

The Relationship ◽

Work Loop

The work capacity of segments of atrial and ventricular muscle from the frog Rana pipiens was measured as a function of muscle length using the work loop technique. Both the work done during shortening and the work required to re-lengthen the muscle after shortening increased with muscle length. Net work increased with length up to a maximum, beyond which work declined. The optimum sarcomere length for work output was 2.5-2.6 microns for both atrial and ventricular muscle. Isometric force increased with muscle length to lengths well beyond the optimum for work output. Thus, the decline in work at long lengths is not simply a consequence of a reduction in the capacity of heart muscle to generate force. It is proposed that it is the non-linear increase in work required to re-lengthen muscle with increasing muscle length which limits net work output and leads to a maximum in the relationship between net work and muscle length. Extension of the results from muscle strips to intact hearts suggests that the work required to fill the ventricle exceeds that available from atrial muscle at all but rather short ventricular muscle lengths.

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213Traditional Japanese Diet Score and healthy life expectancy - a longitudinal global study

International Journal of Epidemiology ◽

10.1093/ije/dyab168.310 ◽

2021 ◽

Vol 50 (Supplement_1) ◽

Author(s):

Tomoko Imai ◽

Ayako Sezaki ◽

Keiko Miyamoto ◽

Chisato Abe ◽

Fumiya Kawase ◽

...

Keyword(s):

Life Expectancy ◽

Rate Of Change ◽

Healthy Life Expectancy ◽

Mixed Effect ◽

Healthy Life ◽

Global Database ◽

Food Components ◽

The Relationship ◽

Diet Score ◽

Japanese Diet

Abstract Background Traditional Japanese diets are considered to be health and longevity. We created a Traditional Japanese Diet Score (TJDS) and investigated the relationship between the TJDS and healthy life expectancy (HALE) longitudinally using global database. Methods Average food (g/day/capita) and energy supply (kcal/day/capita) by countries were identified by the Food and Agriculture Organization of the United Nations Statistics Division database. The sum of characterizing traditional Japanese foods supply (beneficial food components in Japanese diet; rice, fish, soybeans, vegetables, eggs, seaweeds, food components not use so much in Japanese diet; wheat, milk, and red meat) were divided as tertile (beneficial food components;-1, 0, 1, not use so much food components; 1, 0, -1). HALE values by country were derived from the Global Burden of Disease 2017 database. The longitudinal effects of TJDS on the rate of change in HALE from 1990 to 2013 were evaluated using a generalized mixed-effect model (GLMM), which takes into account the dependence of repeated observations within countries. The interaction between TJDS and survey year was applied to access the effects on HALE. This study covered 137 countries with populations of 1 million or greater. Results Longitudinal analysis controlled for covariates showed that smooth term of the interaction between TJDS and survey year was significant (p < 0.001). The TJDS was negative associated with HALE in 1990, and in 1991, but positive associated after 2002. Conclusions The relationship between the TJDS as a healthy eating style and HALE is getting stronger since the 21st century. Key messages Well-balanced eating habits of traditional Japanese diets is supports healthy life expectancy.

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An improvement to the ANN-enhanced flow rating method

10.5194/egusphere-egu21-221 ◽

2021 ◽

Author(s):

Bernhard Schmid

Keyword(s):

Neural Network ◽

Electrical Conductivity ◽

Water Resources ◽

Flow Rate ◽

Major Ions ◽

Rate Of Change ◽

Data Set ◽

Input Variables ◽

Relationship Of ◽

The Relationship

The work reported here builds upon a previous pilot study by the author on ANN-enhanced flow rating (Schmid, 2020), which explored the use of electrical conductivity (EC) in addition to stage to obtain &#8216;better&#8217;, i.e. more accurate and robust, estimates of streamflow. The inclusion of EC has an advantage, when the relationship of EC versus flow rate is not chemostatic in character. In the majority of cases, EC is, indeed, not chemostatic, but tends to decrease with increasing discharge (so-called dilution behaviour), as reported by e.g. Moatar et al. (2017), Weijs et al. (2013) and Tunqui Neira et al.(2020). This is also in line with this author&#8217;s experience.The research presented here takes the neural network based approach one major step further and incorporates the temporal rate of change in stage and the direction of change in EC among the input variables (which, thus, comprise stage, EC, change in stage and direction of change in EC). Consequently, there are now 4 input variables in total employed as predictors of flow rate. Information on the temporal changes in both flow rate and EC helps the Artificial Neural Network (ANN) characterize hysteretic behaviour, with EC assuming different values for falling and rising flow rate, respectively, as described, for instance, by Singley et al. (2017).The ANN employed is of the Multilayer Perceptron (MLP) type, with stage, EC, change in stage and direction of change in EC of the M&#246;dling data set (Schmid, 2020) as input variables. Summarising the stream characteristics, the M&#246;dling brook can be described as a small Austrian stream with a catchment of fairly mixed composition (forests, agricultural and urbanized areas). The relationship of EC versus flow reflects dilution behaviour. Neural network configuration 4-5-1 (the 4 input variables mentioned above, 5 hidden nodes and discharge as the single output) with learning rate 0.05 and momentum 0.15 was found to perform best, with testing average RMSE (root mean square error) of the scaled output after 100,000 epochs amounting to 0.0138 as compared to 0.0216 for the (best performing) 2-5-1 MLP with stage and EC as inputs only. &#160;&#160;&#160;&#160;ReferencesMoatar, F., Abbott, B.W., Minaudo, C., Curie, F. and Pinay, G.: Elemental properties, hydrology, and biology interact to shape concentration-discharge curves for carbon, nutrients, sediment and major ions. Water Resources Res., 53, 1270-1287, 2017.Schmid, B.H.: Enhanced flow rating using neural networks with water stage and electrical conductivity as predictors. EGU2020-1804, EGU General Assembly 2020.Singley, J.G., Wlostowski, A.N., Bergstrom, A.J., Sokol, E.R., Torrens, C.L., Jaros, C., Wilson, C.,E., Hendrickson, P.J. and Gooseff, M.N.: Characterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales. Water Resources Res. 53, 4124-4141, 2017.Tunqui Neira, J.M., Andr&#233;assian, V., Tallec, G. and Mouchel, J.-M.: A two-sided affine power scaling relationship to represent the concentration-discharge relationship. Hydrol. Earth Syst. Sci. 24, 1823-1830, 2020.Weijs, S.V., Mutzner, R. and Parlange, M.B.: Could electrical conductivity replace water level in rating curves for alpine streams? Water Resources Research 49, 343-351, 2013.

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