Physics - Science topic

Yes

The frequency of the system is a constant because it is essentially the square root of stiffness divided by mass with some variation due to boundary conditions. As long as these remain constant, so will the frequency. The rotational frequency is different and, as you have observed, changes with the frequency of the electrical supply.

Peres, L., A. Bou, C. Cornille, Damien Barakel, and P. Torchio. "Work function measurement of multilayer electrodes using Kelvin probe force microscopy." Journal of Physics D: Applied Physics 50, no. 13 (2017): 13LT01.

Hi Lokesh,

Can I ask more about your goals with this project? You can in principle get almost any conductive material to act as either a cathode or an anode based on the potential you apply to that material, so long as you have a counter electrode to facilitate the closure of the circuit. The question is how good of an anode or cathode your material is, and that will largely depend on what reaction you want to occur within that material or at its surface.

To give a concrete example - and sorry here if I am using a different sign convention (these things can be tricky, but I come from a U.S. Chemical Engineering background): if I apply a cathodic (negative/reductive) potential to a platinum electrode in a conductive aqueous solution, I'll drive a net cathodic/reductive reaction (such as hydrogen evolution). If I apply an anodic (positive/oxidative) potential to that same platinum electrode in that same aqueous solution, I'll drive a net anodic/oxidative reaction (such as oxygen evolution). And if I have two platinum electrodes in the system at the same time, then one can act as a counter to the other; one will drive hydrogen evolution, and the other, oxygen evolution. There is nothing different about the electrodes or the solutions they are in, except the fact that I am controlling the relative potentials of the electrodes through the input of energy into a potentiostat (or similar device). Note: this is an electrolytic example, but I'm happy to discuss things from a galvanic cell perspective if that is more useful.

Best wishes,

Kindle

To teach only distinguished students by any way even if you are failing Teacher. Such students are independents

Dear Abin Alex,

It's a very very important question related to engineering and technology.

The basic idea lies in Physics.

We know the measurement procedure of resistivity of any arbitrary shape of two dimensional object by Van der Pow method.

But , for three dimensional object , I am also trying to find a solution of Calculation of the resistance.

I tried to calculate the resistance of a solid sphere between two diagonally opposite points. But it's so lengthy process.

I am not satisfied. For the any two corner point of a cube, I don't find any solution.

Thanks

N Das

An alternative method of demonstrating stability is given by Vasile Mihai POPOV, a great scientist of Romanian origin, who settled in the USA.

The theory of hyperstability (it has been renamed the theory of stability for positive systems) belongs exclusively to him ... (1965).

See Yakubovic-Kalman-Popov theorem, Popov-Belevitch-Hautus criterion, etc.

If the Liapunov (1892) method involves "guessing the optimal construction" of the Liapunov function to obtain a domain close to the maximum stability domain, Popov's stability criterion provides the maximum stability domain for nonlinearity parameters in the system (see Hurwitz , Aizerman hypothesis, etc.).

Hi,

Actually, the influence of inductance value in a coil on TMS is eddy current strength. In addition, the coil design in physical configuration can affect the TMS distribution or depth. The TMS coil with eight shapes is commonly used in clinical application due to better high resolution than the round coil.

You can refer to the article below. Good luck!

I don't think that is appropriate and it is against the scientific ethics.

Thank you so much for pointing out the article, Dear Cüneyt Altındaş.

I see that it is related to a time symmetry breaking state and that there were two possibilities, classical and quantum time crystals.

I will try to understand the idea of the classical time crystal. The authors point out two simple hamiltonians, with broke spatial and inversion symmetry. They find some lagrangians that would be interesting to compare to the lagrangian of isotropic crystals.

Natalia S Duxbury > “Particle is a real physical object. But what is the wave made of???? Wave function is a mathematical construction”.

Very well said, could not agree more! Theoretical physics for the last (more than) hundred years and specially since Albert Einstein has been an enormous waste in terms of human, natural and economic resources and most of all at the heavy cost of intellectual advance of humanity.

The truth is that formally trained modern theoretical physicists unwittingly follow a philosophy/epistemology (a branch of knowledge that they routinely disparage!), namely Kantianism that has already been discredited long ago by G.W.F. Hegel, the worthy protégé of Kant himself! Modern theoretical “physicists” - following Einstein, are not concerned with knowing objective reality as it is in-itself (ontology), but only with the subjective data (epistemology) they can gather about it; so in actual sense they are trying to understand the working of their own minds, rather than external reality!

The Kantian premise is that objective reality is a messy, chaotic, unwieldy and unknowable thing-in-itself; because it does not follow the pristine precincts of good old commonsense, causality, formal logic and the notions of rationality that have been developed by philosophers starting from the early Greeks. The only thing man can do (Kant posited) is to use his sense perceptions, experimental data, his thought, imagination, fantasy or whatever subjective data he can gather about the objective reality to get on with life. What man at best can do, is to organize this data through his subjective thought, mental tools, logical schemata, mathematical (geometrical, algebraic, symmetry) structures and representations, logical categories, theories etc. to get as much of an “understanding” of objective reality as possible, to deal with it comfortably! A good theory is the one that can cover as much of this data, as well as future possible ones (predictability). This is what is historically known as scholasticism - an endless debate to justify one's subjective choice from various theories; but there is no way to judge who is right, except the power of individual’s proficiency in debating skills!

After the quantum phenomena, the Kantian view of the world became a "self-evident truth" for natural science, if there was any doubt about it before, at all. Theoretical physics led by Albert Einstein embraced the Kantian view of the world whole heartedly and universally and like Moses led an Exodus of the physicists to the promised land of thought and mathematics - his "Castle in the Air", as we see now. According to the Kantian view, objective reality is like an invisible Cheshire cat, which remains unknown, we only deal with the “smile” of the cat that we can perceive through our sense perceptions and process through our subjective mental tools.

From a materialist dialectical world view (that I subscribe to) the quantum phenomena is the most fundamental aspect of objective reality, which abolishes “spacetime” or any other esoteric “fields". All forces are mediated by the exchange of virtual particles. The virtual particles become real particles if enough energy equivalence of their mass is available. Light at all wavelengths are particles that can propagate as wave. Please see the following articles and other related publications, questions and comments in my RG profile:

Ambartsumian, Arp and the Breeding Galaxies:

http://redshift.vif.com/JournalFiles/V12NO2PDF/V12N2MAL.pdf

Rubén Barone thank you for sharing information, i would like to read more about it.

Thank you very much

LanguagesEnglishAccessProvidersElsevierCostSubscriptionCoverageDisciplinesLife sciences; social sciences; physical sciences; health sciencesTemporal coverage2004–presentGeospatial coverageWorldwideNo. of records69 millionLinks

Thankyou everyone for replying!

Dear Shannon,

I agree with colleagues above to calculate the energy demand for charging a battery with 28 volt, and 60 Ah. It is required to set the depth of charge such that to preserve its lifetime. May be 80 percent for lithium ion batteries are acceptable but you have to review it returning to the data sheets of the battery.

So need to charge the battery for .8x 60= 48 Ah.

The charging time depends on the charging current.

One must be aware there is specific nominal charging current for any battery.

Physically the such battery size is composed fro an assembly of battery cells.

For space it is always advisable to divide them into units which can better handled

and also that may allow a total more nominal charging current.

Such that you charge it in smaller time than the sun shine period.

So the period of charging is dictated by time of sunshine, then it remains to select the battery of the group of batteries that will satisfy the nominal charging current.

The Ah=48= Nominal charging current x sun shine hours. For charging form the PV generator you need to put a controller between the Generator and the battery

to grantee the safe operation of the battery.

For the best charging method of the battery please see the paper:

The needed energy will be more than the stored energy because the charging process efficiency is less than one. So one has to divide the stored energy by the efficiency to get the total required energy from the charging electric generator.

As for the thermal variations, as the battery will be in a container with the electronics the whole container will be thermally regulated to reduce the temperature fluctuations to that can be accommodated by the components.

Best wishes

To answer to some of the statements made before:

First, it is moot to discuss whether UFOs are real or not. UFO means "unidentified flying object". One may doubt whether some of these objects were really observed. But there are enough reports about cases where there undeniably was some observation but no subsequent identification. So, clearly UFOs existed and continue to exist, but their explanation may be mundane in all cases.

Second, the discussions of the different times that are in use in physics somehow miss the point. Of course, each (pointlike) object with a mass has a proper time and another observer may relate this to some global time by a rate different from one. But that does not change the fact that the dynamics of that object is described by a differential equation that can be formulated using a single independent time variable (and three independent spatial variables). So the "dimensionality of time" is always one, so to speak. (Except in the case of a complex time alluded to above, but that is not connected with any physics, apparently.)

So the interesting question is this: are there cases in physics where the dynamics of an object depends on more than a single time? I don't know of any actual theories in physics setting up such a kind of dynamical equations. In science fiction, there is a situation, where multiple times appear. That would happen, if time travel were possible and the past could be changed. The only way to avoid logical contradictions then (causal loops like the grandfather paradox) would be that when you travel in the past, you arrive in a parallel time line. So time would have two coordinates, one corresponding to the ordinary time and the other describing an "orthogonal" shift in "time" by which a parallel universe would differ from ours. So when you travel to the past you land at a point that is shifted in that orthogonal time (or else you shift orthogonally by landing) and the future of that world, which up to the point in ordinary time where you end up with your time machine would have had the same history as your own, would be open. So you could change things, but the changes would pertain not to the world you came from, but to one shifted in the second time direction. Time would be essentially two-dimensional and time travel to the past would force you to shift you away from the one-dimensional line on which you lived.

But as I said, that is science fiction.

Dear Shannon Mutch

welcome,

wish you success in designing and constructing you panel.

I think you can use the a hybrid solution. That is to mount the solar cells on the body of the rover and make an extension aluminum plate which is oxidized to mount on it the rest of required solar cell array.

Since there is no rain then you must can construct the encapsulation from sheets of glass covering the solar cells without cementing them to the cells.

The most important thing that you support the cells protecting them from the environment with the minimum weight and highest strength.

I think you you can satisfy the weight budget of the PV array.

I would like to introduce the encapsulation ideas for terrestrial panels but they will be mounted in desert.

You may find some inspiration in them:

and

Best wishes

It is possible experimentally by the ESR or EPR seupts

Dear Dr. Faisal,

The following pdf file of a research paper published in Agricultural and Forest Meteorology (Kandel et al., 2018) may be of some use for your reference on temperate peat soil.

With best regards

P.S. Brahmanand

Dear Quentin,

the open circuit voltage is determined by the difference of the quasi-fermi-levels. Therefrom you can differ the following cases:

- In low doped semiconductors and at low excitation levels you have V_oc/Vg < 1 as expected.

- In degenerated material you have V_oc/Vg >1 because the fermi-level lies within the bands.

- At high excitation levels (excess carrier concentration compares with the equilibrium concentration) the quasi Fermi level shifts into the bands due to the fact that the bands are filled with carriers. In this nonequilibrium case you find V_oc/Vg > 1 too.

With Regard

R. Mitdank

📷Preston Guynn. added a reply on June 19, 2019:

Force, mass, and energy are a parallel set of descriptions of the effects of special relativistic Thomas Precession. All matter and space, and their interactions are described with distance in three dimensions, time, and their derivatives.

Newton's first law of motion is , "Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it."

Yet the concept of motion requires at least two objects, and if there are two objects, then there is always an external force, which is gravitation.

So the idea of rewriting Newton's laws without force (or mass or energy) is good, but it should be extended to incorporate the most basic non-linear effects of motion in space time, which are special relativity and Thomas Precession.

See my article describing the recent discovery of the effects of Thomas Precession the particle and galactic scales.

Article Thomas Precession is the Basis for the Structure of Matter and Space

Recommended / Share

Thank you very much Dr. Abdelkader Mohamed Elsayed and Dr., Rashid Nasrolahpour ! I greatly appreciate that!

It is always good to return to the original definition and meaning of the terms.

Entropy is often correlated with the disorder but not always. Entropy is the measure of unknown information. How do we understand this? The trick is to understand what is macrostate and what microstate.

* Macrostate is observable value.

* Microstate usually not.

Unknown are microstates as we can not measure them.

Just an example with a dice, where we can observe microstates. Macrostate is the sum of all values of all thrown dice. The trick is that there are existing many microstates giving one macrostate. Not every macrostate has the same number of microstates.

Macro states with the highest number of associated microstates have logically the highest probability to be observed in the system as far as all microstates have the same probability It leads to the original Boltzmann definition of entropy.

When there are microstates with different probabilities, we just group them together and we get the well-known definition of Boltzmann entropy and similar Shannon entropy

H = - sum(p_i * ln(p_i))

They are the same except for the Boltzmann constant.

This link maybe useful:

If I may, I suggest you read "More Heat Than Light" (Mirowski). It's a comparative history of economics and physics. And you can explore the "complexity economics" area, too.

Answer : As the magnet approaches the ring, the distribution of the magnetic field around the ring changes. Changing the distribution of the magnetic field around the ring leads to the generation of an electric field (on the ring plate). This electric field can change the distribution of ring electrons. Changing the electrons of the ring can create an induced potential in the ring circuit. The induced potential generated in the circuit circuit generates the induced electric current in the circuit circuit. (You can track the appropriate calculations from Maxwell's equations (especially the third and fourth equations)) Hope you got the answer right.

Non-hermitian means that the operator does not have its self-adjoint:

T \ne T*

Without a self-adjoint, there is a missing symmetry and unitarity in operations in Hilbert or Banach space. The solutions are therefore complex, and the eigenvalues also. Such eigenvalues have therefore no direct physical meaning, unless they are either scaled by some complex number (see Nimrod Moiseyev works), or the operator is made self-adjoint in a bounded domain where it gives real eigenvalues.

Respected D Abbott

Very good question but ans is difficult.

I don't tell anything about aliens.

I just want to tell some thing about mass.

So far as I think is that The Principle of extremum action as the basis principle of natrure.

Action is , you know, actually the world length between two events.

More precisely action is proportional to world length between two events.

The proportionality constant is something called "mass" ( with a negative sign) .

So, if we don't want to consider mass as a variable, we will fail to explain the time evolution of systems of different mass and Physics will not be able to explain the natural events.

Though, for Fields , mass is not the proportionality constant of action because for fields like EM field ,there is no mass.

I don't know whether the time evolution of a massive system can be explained without mass or not.

Thanks and Regards

N Das

Joseph Tham, thanks for a thought provoking question. I think we should tolerate and respect beliefs and ideas that are not considered scientific. Our intolerance of such beliefs and ideas could be the result of a lack of understanding of the science behind them. We should therefore subject them to rigorous testing using the scientific method. A practical example is the fact that the World Health Organization has not dismissed out of hand the herbal remedy from Madagascar that is claimed to prevent illness from COVID-19. Instead the remedy is going to be tested using established scientific principles. The null hypothesis can then be rejected or accepted. This is how Indigenous Knowledge Systems contribute to scientific advancement.

Dear Prof. Ziaedin Shafiei

As a conservative physicist & non-expert in relativity, I would like to answer your question in the following way, as it is elaborated in Landau & Lifschitz classical book: the Classical Theory of Fields. They introduced the idea of the light cone many years ago to described events in space-time in a general way. For them: time is an axis, space is another axis & 1/c the inverse speed of light is the slope of the plot. Hereby, my answer is: t is the time.

Does this work?

One fundamental problem I am facing how to see the frequency components (in ewfd physics, frequency-domain study) in COMSOL other than the excited one( mean by the mode at other frequencies).

A very simple experiment if I take one 500nm width by 30 nm height Si waveguide (2d simulation), and excite it with 193.42 THz at port 1 end, now if I want to see the frequency components at 300 or 200 THz it should appear null or no field components. But how to observe it in COMSOL (the modes or the field components can be seen at 193.42 THz since it's the excited one).

It is an interesting point Prof. Ziaedin Shafiei

Prof. R. Feynman has some issues about some applications of electromagnetism.

For example: According to Prof. Paulo Roberto Silva, in his famous lectures Prof. Feynman didn´t derive the Drude model for the electrical conductivity. We know that he worked a lot on superconductivity, and in the section called: Tensors chap 31. of 2 Volume Feynman Lectures, he briefly talks about the conductivity tensor j=σ E, but he calls it as tensor of inertia in analogy to the moment of inertia & there he stops to elaborate further. No mention to the Drude model.

All: See

That's a good question

Nice Cotribution Franklin Felber

Nice Dear Joaquin Diaz-alonso

Any good conductor, e.g. a metal surface, reverses the direction of circular polarization on reflection, for all frequencies for which it is a good conductor.

to have actual being; be:The world exists, whether you like it or not.

to have life or animation; live.

to continue to be or live:Belief in magic still exists.

to have being in a specified place or under certain conditions; be found; occur:Hunger exists in many parts of the world.

to achieve the basic needs of existence, as food and shelter:He's not living, he's merely existing. Dictionary.com

Thank you Dirk Luetzenkirchen-Hecht for your kind suggestion. I will try what I have in an older system.

Regards.

For Central Limit Theorem, the random variables are not necessarily gaussian but they have to be independent and identically distributed (in classical CLT). They can come from any distribution. Moreover, CLT is an approximation. Do you have a prior knowledge that the resultant gaussian variable is composed using gaussian variables? In that case, using the convolutional properties of normal random variables can give you an idea.

Natural variables for U: S, V, N_i (for simple systems)

Natural variables for S: U, V, N_i (for simple systems)

T is the partial derivative of U with respect to S, maintaining V and N_i constants:

T=(∂U/∂S)_V,Ni

If from the fundamental relationship U=U(S,V,N) you replace S by T just by solving for S in T=T(U,S,V,N_i) and substituting in U=U(S,V,N), then, you loose information because you are replacing a variable with a derivative with respect to that variable.

This problem is worked out with the Lengendre transform. If you search on internet, you may find simple examples: how to change y=f(x) to z=g(p), where p is ∂y/∂x=2x, in the two ways, the incorrect one (calculation of p and plain substitution of p by removing x) and the correct one (calculation of p and applying the Legendre transform, z=g(p)=px-f). In fact, because you do not loose information with the Legendre transform, you may go backwards from z to y, which is not possible with the incorrect way.

Therefore, it is a mathematical "trick".

Applying the Legendre transform to U, with respect to T and S, you get a new thermodynamic potential F=U-TS, the Helmholtz energy, whose natural variables are T, V, and N_i. Beware of the minus sign applied to the Legendre transform (i.e., F is not equal to TS-U, but U-TS).

For a system at constant U, V, and N_i, any possible process will maximize S.

For a system at constant S, V, and N_i, any possible process will minimize U, but not F.

For a system at constant T, V, and N_i, any possible process will minimize F, but not U.

The Legendre transform connecting two thermodynamic potentials parallels the Laplace transform connecting the corresponding partition functions.

The Legendre transform is not only employed in Thermodynamics and Statistical Physics, but also in Classical Mechanics and other fields.

Dear Ait Mansour El Houssain

By trying to answer your question I found the following reference with many examples on how the zeta functions (the reference doesn´t call it Riemann z functions) are all related in a natural way to eigenvalues of specific boundary value problems.

In statistical physics Z Riemann function is found in:

Bhaskaranand Bhatt

All particles are angular. A sphere is a mathematical concept only.

Mechanics. Newton's first axiom says that, in the absence of an external force, a body either is at rest or moves with constant velocity. In fact, this is a statement opposing Aristotle's view that a force is needed to keep a body in motion at any non-zero velocity.

Other than that trivial movment in the absence of a force, one might argue that quantum mechanical zero-point motion is movement without a force.

So there are several places outside music where movement appears without a force. In fact, I doubt the applicability of the same notion of movement as in physics to the "flow of notes". Movement in music is a different concept from that of movement in physics. The same word has different connotations in different fields. I believe, it would be easy to argue that with a similar change of meaning to the word force, you would find that the "flow of notes" does not happen without a force.

There is a tendency of confusing and therefore (often unintentionally) abusing notions having the same name but meaning different things in different contexts. For example, when people speak about energy they gain by meditation, this has nothing to do with an energy that might be describable by a hamiltonian or be subjected to energy conservation.

Go to https://gracedb.ligo.org/superevents/public/O3/ You will see lots of candidates, 56 to be exact. Half of them have been rejected. The rejected ones, have shape of gravitational waves but turned out to be noise from other sources, such as cleaning equipment. Many "confirmed" ones were detected only by one detector, such as GW190425 (the only confirmed detection from the 3rd run) or GW170817 ( the only one supposedly with a visual). LIGO mistook different types of noise for grav waves before so nothing can be ruled out.

Social physics can be incorporated in development economics.

Thank you very much Dr. P.K. Karmakar !!

The following article is relevant:

This paper presents a novel method of space-based geoengineering which uses the mass of a captured near Earth asteroid to gravitationally anchor a cloud of unprocessed dust in the vicinity of the L1 position to reduce the level of solar insolation at Earth. It has subsequently been shown that a cloud contained within the zero-velocity curve of the largest near Earth asteroid, Ganymed, can lead to an insolation reduction of 6.58% on Earth, which is significantly larger than the 1.7% required to offset a 2 °C increase in mean global temperature. The masses of the next largest near Earth asteroids are found to be too small to achieve the required level of insolation reduction, however, they are significant enough to be used as part of a portfolio of geoengineering schemes.

Cheers

Hi Mohammadreza Arab ,

I wasn't sure how to insert Greek characters in RG answers, so my0 stands for the permeability of vacuum = 4 * pi * 10^-7.

Thank you Dr. !!

Dear M. H. Ashourzadeh

A solution of two ideal gases? in that case the theory for calculating thermodynamical properties in solutions was well elaborated, since molecules do not interact each other in ideas gases and additive properties hold well for the individual components of the mixture.

Please, for a general undestanding of the problem, you could check the book by Acad. L. Landau and E. Lifshitz, Vol. 6, Statistical Physics, Pergamon 1980, Part I, chapter IX---Solutions, #93 Pag. 279.

Abbas N. regarding your 3 points:

1) There is no need for the lens NA to equal that of the fibre. Usually, coupling will be more efficient if the lens NA exceeds that of the fibre, provided the lens aperture (entrance pupil) is sufficiently large to avoid vignetting the input beam.

2) Coupling is optimised when the beam is focussed to a spot whose field profile matches the field distribution of the fibre mode. Typically, both launch spot and mode profile are approximately Gaussian, and the matching criterion is for the launch spot diameter to equal the mode field diameter.

3) Launching the collimated input beam parallel to the optical axis of the lens which in turn is coincident with the optical axis of the fibre will minimise mode mismatch due to tilt errors and lens aberrations.

More specifically, you specify a beam quality factor M² = 1, so the beam is close to an ideal Gaussian beam. When focussed by a lens, the radius of the beam waist at 1/e² intensity, w₀, is related to the wavelength, λ, and the divergence half-angle, θ, also at 1/e² intensity by: θ = M² λ / π w₀

Your collimated input beam width is W=0.65 mm. If the focal length of the lens is f, the radius of the beam at the lens principal plane is W = θ f = f λ / π w₀

provided the lens NA > sin θ. https://www.newport.com/n/gaussian-beam-optics

The fibre mode field diameter will be comparable to the fibre core diameter, but need not be identical. The relationship depends on wavelength, and the extent to which the evanescent field extends into the cladding.

If we assume that the beam spot radius is equal to the fibre radius, w₀ = a = 1 μm, then we require a lens focal length f = π W w₀ / λ = 1.98 mm.

A larger mode field diameter will require a proportionately larger focal length. A 2.8 μm mode field diameter will require a focal length of approximately 2.8 mm. The exact value is not too critical. If the mode field radius is r₀, the coupling efficiency (assuming Gaussian profile for both fibre mode and excitation) is:

η = 4 w_0² r_0² / (w_0² + r_0²)²

A 40% mismatch between launch spot diameter and mode field diameter degrades the theoretical coupling efficiency by only 11% (to 89%).

Regarding the choice between microscope objective and aspheric lens, both are capable of diffraction-limited performance for a monochromatic beam aligned with the optical axis. The microscope objective will be more complex, because it must deliver high resolution imaging over a relatively wide field of view, with illumination comprising a broad range of wavelengths.

The exact focal length of microscope objectives is not always stated. Magnification depends on the distance between objective and eyepiece. Tube lengths of order 160 mm are common, so a crude estimate for high power objectives is focal length f = 160 mm / magnification.

The 60x objective suggested by Suchita Yadav. would have a focal length around 2.7 mm, and would be a reasonable choice, especially if the fibre MFD is larger than 2 μm, but an 80x objective may be better. A 40x objective with 4 mm focal length is probably be too long.

If the microscope objective is optimised for visible wavelengths, there may be some additional losses due to surface reflections at infra-red wavelengths.

Note that a weak supplementary lens can be used to modify the diameter of the beam as it enters the focussing lens, and adjust the spot size for optimum coupling.

Hope this helps.

Dear Derek Oh , please take a look at Prof. Daniel Lidar´s page:

Dear Malcolm White

Thanks for your response.

Actually, I'm aware of setting an infinite ground plane in CST, I was just wondering what are the visual ramifications of adding an infinite ground plane to the structure compared to a finite ground plane?!

Regards

Dear Colleagues,

This point is treated in electromagnetic wave propagation. The speed is limited by the transfer of energy from the magnetic form to the electric form and vice verse.

It is so that the wave is propagated by when the magnetic field collapses it builds the electric rings in the side space and when the electric rings collapse they build

magnetic rings beside them. This this build and collapse lasts some time then the waves takes time to propagate a specific distance.

Best wishes

Hi Abbas

I have the same question! I am trying to fabricate SMF-GIMF-SMF structure for sensor application. I tried many times to splice the fibres. I manipulated with different splicer parameters as prefusion time, overlap, arc power and so on, but almost always I got splice with a black vertical line (fig. 1).

Once I got good splice. It happened when I accidentally broke the bad splice and respliced it again. Unfortunately, I could never repeat it.

At fig.2 you can see two spectrums. The blue one corresponds to SMF-GIMF-SMF with both bad splices. The red one corrensponds to SMF-GIMF-SMF that have one good splice. The second spectrum had a much better contrast then the first one. This is due to the fact that the modes in GIMF fibre are more equally coupled to the SMF fiber. Thus, there is a difference between coupling coefficients of modes in GIFM to SMF fibre for the "bad" and "good" splice.

P.S. Abbas, please, let me know if you will find a method, how to splice it without bubbles and black curves!:)

Radiosondes provide mixing ratios at various pressure levels. These values need to be integrated to obtain the total column value, i.e., total (or integrated) precipitable water in g/cm2. There are a few slightly different integration formulas, which are described in this important report:

Simple and straightforward:

If the space separation between the two freely falling objects is very small, then you can regard them as a single extended small object (a string), therefore all observers see the same fall. BUT, if the space separation is finite (noticeable), then what is the simultaneous drop for the spaceship observer, it is not simultaneous for other observers, and so is the free fall! Space separation is the key!

Dear Prof. Saransh Gupta Maybe you find interesting a reading of the following book: Quasiparticles by Prof. M. I. Kaganov, and Academician I. M. Lifzhits.

I was introduced to the topic of quasiparticles many years ago by one of the authors and I find extremely useful to read the book particularly to understand the use of the phenomenological approach of Quasiparticles in Quantum Solid State Theory. Regards.

Hai Shubham:

The question about inertia would be helpful in getting more understanding of that. Maybe have also considering Newton's laws 3rd, 2nd, & 1st may be more appropriate with physics 3rd law providing the observational aspect that is easy to demonstrate.

Energy & entropy will be coming together with the force definition to moving away from inertia.

Rajan Iyer

ENGINEERINGINC MEDITERRANEAN HELLENIC GLOBAL PLATFORM

There are essentially two ways of looking at this issue. One is Juan Weisz's way - totally correctly making use of wave functions and probability densities.

Another way is to look at the physical mechanism whereby quantum tunneling happens. In a nutshell, to tunnel through an energy barrier, a particle must borrow energy from a nearby virtual particle, and relinquish back that energy to the virtual particle within the alloted permissible time frame (as per Heisenberg's relationship linking virtual energy to permissible duration of virtual existence.)

To tunnel, the particle needs not the presence of a suitable virtual particle nearby: by suitable is meant capable of fleetingly lending out the exact right amout of energy needed for the tunneling event to occur. It is, by the way, the exact selfsame mechanism that allows any individual atom of a radioactive element to decay: there is an energy barrier that must be hurdled before decay can occur, and borrowing virtual energy from a suitable nearby virtual particle is what enables overcoming that barrier.)

The amount of energy that must be borrowed depends on the particle or entity (atom, etc.: anything can tunnel) that must tunnel. If the requisite energy is high, then the occurence of matching virtual particles is statistically rarer (which is why some half-lives are long, and some are short.)

If the energy to be borrowed is low, then separate occurences of tunneling remain statistically independent of anything that happens around - as is for instance the case with carbon-8, which needs so very little energy to decay: there are so many low-energy virtual particles popping up all the time within the quantum foam that no interference with the environment occurs.) When however the requisite tunneling or decay energy is high, then suitable matching virtual particles are much rarer (think osmium-186). In that case: an atom of, say, Osmium-186 could conceivably snap up the rare suitable such virtual particle and thus interfere with and prevent another nearby atom from having its chance at decay - until the next nearby suitable virtual particle pops up, and as such statistical independence could not hold.

For any particular particle or atom, the best is to do the calculation. You can extrapolate the statistics of the appearance of suitable-energy virtual particles from the measured values of half times, see e.g. the table at https://en.wikipedia.org/wiki/List_of_radioactive_nuclides_by_half-life

One thing that comes to mind in regards to your primary question is hydrodynamic quantum analogs. These experiments were done at MIT in July of 2013 published in Physical Review Letters E. Dr. Daniel M. Harris displayed that "a coherent wavelike statistical behavior emerges from the complex underlying dynamics and that the probability distribution is prescribed by the Faraday wave mode of the corral." I hope this helps!

Saida, If you have a look at a Dieke diagram it'll be apparent to you that the energy states of La are well separated (gs and es) way above its bandgap so no emission line will fall in the visible region. And La doesn't have 4f electrons as the other lanthanide ions do. Also, other emissive lanthanide ions which are often used as emitters, have energy levels that are separated by energies falling in the visible range. However, due to the inner shell configuration of these 4f ions, it's very unlikely that you can directly excite a 4f-4f transition in these- so you'll see little-to-no emission intensity. However, if you have La in the material it can absorb the incident energy and efficiently transfer it to the emitting lanthanide ion in an indirect way. But this energy transfer is strong enough that it populates the emissive states of your lanthanide activator and you'll see the fluorescence occurring from them. That's why you see an increase in luminescence efficiency in the presence of La.

Scientific papers are useful for their ideas, not the text. In addition, these ideas evolve with time, so it's not useful, for understanding the technical content, to read the earliest papers on the subject. The only reason to read Carnot these days is for the history, not the technical content. Any textbook on thermodynamics will do.

Dear Gabris Mahamid, Such a database aggregated and sorted at this stage is being developed. It has not been tested and therefore cannot be seen. The development is of large companies such as: Web of Science, Scopus, Google Scholar and Google Academia, Microsoft Academic, Semantic Scholar and others. There is only a partial finding at this stage of these data companies on specific topics in specific areas. Wishing you success in research. Emil Yankov

with your resolution and expected density, it could be borderline. If you are unable to see H-beta, I'd suggest a higher lying line, like H6-H8, see PHYSICAL REVIEW E 75, 016401 (2007)

Thanks for your message Priya Dharshana.

I am looking for a sample not for a template.

A magazine is definitely not the same as a Journal. Magazines normally carry popular articles, not original work. A Scientific Journal publishes original scientific work not published elsewhere. 'Letters' or 'Notes' are of shorter length. It may include a comment on an already published recent paper by the author or someone else. Normally, Editor takes decisions on 'Letters' and 'Notes'. Seldom are they are sent to reviewers.They get published quickly. A full length paper in a reputed Journal has to undergo peer review process and may take up to an year or so to get published.