Doppler - Science topic

@dokov, may I point out a few differences between the group of circles whose name I am trying to find and the objects in the references you kindly suggested? (1) The group of circles I mentioned has their centers fixed while expanding. (2) The spacing between the circumferences in any given angular direction is constant. (3) The first circle will always enclose all the other circles; the second one will always enclose all the circles except the first one, and the third will enclose all except the first and second, and it continues.

It is not a question infact, it is a discussion on being or not being that the true nature of DE is energy momentum exchange between matter and radiation.

My Summary on He-2-4 has been hitting records as "Most Read Question" across Physics Departments all over the world.

Hi Audrius Merfeldas ,

I did not find the link you mentioned to be very helpful, so I went in search of original source materials. I first tried Wikipedia: https://en.wikipedia.org/wiki/Doppler_radio_direction_finding . Their explanation of how pseudo-Doppler DF worked was that the technique used phase differences. They also referenced a 1987 book [1], which also mentioned on p. 122 that the technique, pseudo-Doppler DF, was also called "sequential phase" DF. Chapter 9 of this book shows one how to actually build such a DF, and it mentions a number of pitfalls when trying to get such a circuit to work: 1) multipath (p. 136), and 2) grounding of the non-active antennas (the non-active antennas must float, electrically, if they are grounded they tend to reradiate the incoming signal, see p. 130).

[1] also referenced a 1981 article by David C. Cunningham on desining and building a pseudo-Doppler DF, see [2]. The article also mentioned that Cunningham had patented his design. I looked up his US patent (granted on Novmeber 5, 1985), US Patent No. 4,551,727, on the following URL: https://ppubs.uspto.gov/pubwebapp/static/pages/ppubsbasic.html To obtain a PDF of a US patent, simply enter the patent number, without its commas, in the "Quick lookup" field at the top of the page. Cunningham's patent cites the June 28, 1941 US patent, US Patent No. 2,414,798, by Horace T. Budenbom showing the rotating antenna DF - the word 'Doppler' was not used. The antenna at the edge of the rotating disk phase modulates the incoming signal. Cunningham's patent also cites the 1947 article discussing the square array of electronically commutated aerials [3], notice the title of this article.

[1] Joseph D. Moell, Thomas N. Curlee; Transmitter Hunting, Radio Direction Finding Simplified; TAB Books; 1987; see Chapter 9 Doppler DF Units, pp. 120-141; URL: https://archive.org/details/curlee-t.-n.-moell-j.-d.-transmitter-hunting-radio-direction-finding-simplified-1987-tab-books

[2] David Cunningham; DF Breakthrough!; 73 Magazine; Vol ...; No. ...; June 1981; pp. 32-46; URL: https://archive.org/details/73-magazine-1981-06

[3] C. W. Earp, R. M. Godfrey; Radio direction-finding by the cyclical differential measurement of phase; Journal of the Institution of Electrical Engineers, Part IIIA: Radiocommunication; Vol. 94; No. 15; March-April 1947; pp. 705-721.

Regards,

Thomas Cuff

The energy in field has mass. It take energy to set up even a static field.

Cuma Tyszkiewicz

Hi ,

In terms of accuracy, the specific accuracy of doppler lidar measurements can vary depending on several factors, such as the quality and capabilities of the lidar system itself, atmospheric conditions, and the distance between the lidar instrument and the target. It is challenging to provide a specific accuracy value without detailed information about the specific lidar system and its calibration.

Modern doppler lidar systems can generally provide accurate measurements of air flow velocities, including the vertical component in thermals. The accuracy can be within a few centimeters per second for low-velocity flows and up to several meters per second for higher-velocity flows.

It's important to note that the accuracy of the measurements can also be influenced by factors such as turbulence, the presence of aerosols or particles in the air, and the stability of the atmospheric conditions.

These factors can introduce some uncertainties in the measurements.

In the context of applications like SeeYou Navigator, which provide information about thermals for sailplane pilots, the accuracy of the doppler lidar measurements can be further enhanced by using additional data sources and advanced algorithms to improve the estimation of thermals' characteristics.

Overall, it is always advisable to consider the specific capabilities and limitations of the lidar system being used and consult the documentation or specifications provided by the manufacturer for accurate information on its accuracy in measuring vertical air flow speeds.

Could you rotate your plexiglass chamber on the few degrees away from normal orientation relatively incident beams? In such a way reflected beams from camera walls will be directed out of measurement volume.

Note in the past magnetic bottles operated at temperatures that have Browning motion velocities much below relativistic. Now they are hotter with more electromagnetic induced motion. When and if they produce much fusion there a lot of emitted particles in them moving at relativistic velocities.

Hello Ritesh,

Returns from an FMCW radar are shifted in frequency due to two effects: (i) the range delay and (ii) Doppler shift from moving targets. For typical parameters, the range delay frequency is much greater than the Doppler shift (often by a few orders of magnitude). Therefore, the phase of returning samples changes rapidly due to the range delay but the phase due to the Doppler shift changes over a much longer timescale. This allows us to make a useful approximation when the duration of the chirp is short (as is often the case for automotive radars that repeat the chirp many times within a beam dwell time).

Let us consider, as you say, M samples per chirp and N chirps, giving a total of M * N samples. We can designate the samples as x_m,n where the index m refers to the sample number (m=0,1,2...(M-1)) and n refers to the chirp number (n=0,1,2,...(N-1)).

The M samples taken over an individual chirp (say, for example, the n^th chirp, i.e. samples x_{m=0,1,2,...(M-1),n}) exhibit a phase gradient due mainly to the range delay. If we assume the phase variation due to the Doppler to be negligibly small over the duration of the chirp then we can say that any phase variation in the M samples taken during each chirp is due to the range delay. An FFT of these M samples yields a frequency, f_R, that is indicative of range, where:

Range = c*f_R /(2K), where K = B/T and is the gradient of the chirp [Hz per second], B is the total chirp bandwidth and T is the duration of the chirp.

Hence the FFT of the M samples is a frequency plot that scales to a RANGE plot.

If we now consider any one of these samples (say, for example, the m^th sample) across all N chirps (x_{m,n=0,1,2,...(N-1)}), they will have a reasonably consistent phase due to the range delay because the samples are all drawn from the same position within the chirp, but they will now exhibit a slower rate of change of phase due to their Doppler shift. The slower rate of change of phase is evident over the longer timescale of N chirps. The Doppler induced phase gradient is due to a small variation in range (in the order of the wavelength) over the timescale of the N chirps. An FFT of consistent samples across the N chirps will therefore yield the Doppler shift frequency, f_d, from which we can deduce the radial velocity, V_r, of the target as:

V_r = lambda*f_d / 2 where lambda is the wavelength.

Hence the FFT of the N samples is a Doppler frequency plot that scales to a (RADIAL) VELOCITY plot.

The 2-dimensional FFT of your array is therefore a RANGE-VELOCITY plot (after suitable scaling).

Note that the approximation that the Doppler induced phase variation during a single chirp is negligibly small does break down in some radar applications, i.e. those using a long chirp duration and/or where high target velocities can be encountered. In that case we can resolve the range delay frequency and the Doppler frequency over two chirps; an up ramp and a down ramp, giving a triangular frequency modulation.

I hope this helps.

Best regards,

Clive Alabaster

Director & Consultant

White Horse Radar Limited

Following are the reason for hematoma-

-Anticoagulants use

-unnoticed vascular injury with needle

- ultrasound-guided intervention

Femoral artery injury Proximal vs distal more with distal

Shouxing Qu This is exactly what I have been looking for.

I wanted to generate a baseband signal and then add doppler frequency shift and code phases later on.

Hello everyone, I'm sorry I don't have an answer. But since this thread is related to flow visualization, I would like to let you know that we've started a Flow visualization Stack exchange forum. We are building a community currently. Once we have 60 people we will be allowed to proceed to a private beta version of the forum. Please join us if you are interested in flow vis and have questions to ask. Here's the link: https://area51.stackexchange.com/proposals/127312/flow-visualization?referrer=NTJlZjIyYzI3Zjk4N2I1NDZmMTJhZDUxMTViODcwMWUyNTM4OTI1YTU1OTYxN2ZkNDcwY2U2ZWI5NmU2OTY5OGhTtnNa4jEjFBFgB4o_K-u-LTdCqWX8yd8vul6HHcUb0

Ana María Rojas-Gómez check your inbox i have sent you

Sir, i am also wandering same but in general angle should be less than 60 and close to 20, this is what came to know from reading some literatures.

even i wish to know wether angle is auto adjusted once set in the machine even after movement of probe.

thank you

We employed LVS to long range (>>100m) projects, so I am not experienced with he Polytec MSA-600 (we employed a Litton CO2 (NVL) system as well as a modified Polytec model made for long range effort. However, you may wish to contact the authors (Alaa Elhady and Eihab M. Abdel-Rahman) associated with he attached article -- they employed the same MSA-600 model you asked about. Hope this helps. TDC

Dear Srihari Pathipati ,

Look the link, maybe useful.

Regards,

Shafagat

it is nice subject

See also the following link: https://forschungsinfrastruktur.bmbwf.gv.at/en/fi/laser-scanning-vibrometer-psv-500-hv_3974

Dear Umer Khalid all these methods are different, but they have a joint qualification as quasi-optimal methods. The optimal method is the Maximum Likelihood Method (MLM). Only ML can efforts Kramer-Rao Bound of dispersion of estimation parameters (angles of arrival as well)

In classical terms i think the explanation for this is hidden in work energy theorem,which states that change of K.E. is work done then if we can say that work done is stored in form of K.E

Now if we calculate work done which is equal to force ×distance

And F=Ma,

And a=dv/dt

Distance=vdt

So work done = mdv/dt.vdt = 1/2mv^2( if intial velocity u=0)

But main point to be note down here is we can just take a=v/t and d=vt ,which end's up with E=mv^2,but here velocity is not constant throught the distance (s) so we have to take calculus approach

If someone is not comfortable with calculus approach so he can think in terms of average velocity which is equal to u+v/2 then their arises the factor of 1/2 .

Hope I am able to add something in discussion

From one of the best group in the field :

Preston Guynn : " If Pound-Rebka showed a relationship between their gravitational time dilation result and the second order Doppler effect ... "

They didn't. They were attempting to measure the gravity-shift across a few floors of a university building. They used a "recoilless" Mossbauer emitter and absorber, in order to get a very narrow spike in the frequency response, necessary to measure very small shifts.

What they found was that the Mossbauer hardware didn't behave as predicted, and instead showed a temperature-dependent redshift, which they then had to try to minimise by using cryogenic cooling.

As soon as the receiver identifies the satellites using Doppler values, then that will no longer be the cold start but rather the warm start. At this stage, the receiver uses the recent almanac in memory to map the satellites and their Doppler offsets. Thus, what is necessary is only to check the anticipated pseudorandom noise (PRN) codes at the expected Doppler offsets. Henceforth, searching the sky becomes worthless.

How can we determine the satellite during cold start?

++++++++++++++++++++

Other than using the Doppler values, the positions of the other satellites may be detected using the orbital data from the almanac. In any given constellation, each satellite transmits orbital parameters for all satellites alongside auxiliary health and status information. Since the ephemeris data is transmitted only for each individual satellite, then you may simply compute the satellite positions using the orbital equations at any given point in time.

++++++++++++++++++++

Apart from that, you may get the ephemeris and clock information from the cellphone link rather than through the satellite link, a concept which may be termed as assisted satellite positioning. The strength of this approach is that the amount of time required to get all the critical information shortened.

++++++++++++++++++++

While the orbit design has something to do with the overall satellite configuration, the receiver architecture has a vital role in the task of identifying the satellites in order to calculate its own 3D position and clock offset, on the other hand. Therefore, the overall cold start searching time may improve with multi-corellator and high-sensitivity Global Navigation Satellite System (GNSS) receivers.

NOMA has shown many advantages and was extensively studied, but I don't think it is currently standardized for the 5G system.

The Doppler center (line) depends on the S/C position, velocity in the Rotating Earth-fixed (ECEF) Coordinate system. So formally you would need orbital information. Luckily the orbital tube Sentinel-1 is controlled accurately, and provides a quite stable S/C position and velocity as function of Sentinel-1 Ascending Node (ECEF) crossing (time). This crossing time oscillate with magnitude of 0.3 sec and precesses some +7 seconds per year. So a previous estimate of the Doppler center for a particular UTC time (N times 10 days apart) might help to obtain a guestimate for the next Doppler line at UTC (0) + N x 10.0 days + N x 10/365.25 x 7 sec

Thanks - appreciated. Do you have a paper that I can reference.

Have a look at features merging : https://stackoverflow.com/questions/28445441/how-to-combine-two-or-multiple-kinds-of-features-as-one-final-feature-to-build

https://ieeexplore.ieee.org/document/7376629

Dr. Jackson, Yes, Gupta's maths is correct, and that's all that matters at the moment. The implication is that the Lorentz transformation Doppler analysis over two paths is equivalent to two separate classical analyses.

If such an analysis only operates over a return path, then we won't have any of the conundrums associated with what the speed of light is measured relative to.

Your remedial theory about the light slowing down after the collision was designed to address a conundrum which may not exist.

So the title question is "do we have any experimental evidence confirming the LT Doppler shift analysis over a one-way path?"

That would mean experiments where the Doppler effect in light is measured first with the receiver moving relative to the source and then with the source moving relative to the receiver to see if the result is different. Have any experiments like this ever been performed to any degree of accuracy? It would have to involve very high terrestrial speeds in order to reveal any significant effect.

The fact that Gupta has shown the LT Doppler analysis over a two-way path to be equivalent to two separate classical analyses, is quite persuasive that maybe it only holds over a two-way path and that we have both been until now trying to solve a conundrum that does not exist.

Considering your information about the mirror/reverberation effects, you may have to understand where the doppler effect in this environment comes from:

A (sonic) wave propagating WITH some flow is traveling faster (at the added velocity of sound and flow), a wave propagating AGAINST some flow slower. While it might be hard to understand, the Doppler shift of signal traveling back and forth the very same path of flow is non-zero (due to differing traveling times).

Consider a signal that's reflected - traveling the (about) same path twice: it's Doppler shift will be about twice as large (compared to a single travel), as it is exposed to the flow twice.

My best guess is that your mysterious signals stem from exactly this effect - about doubling the Doppler shift for a signal reflected twice as compared to the "standard" signal.

In Wesley`s 1986 paper:

https://link.springer.com/content/pdf/10.1007/BF00735382.pdf

"Voigt thereby obtained the relations that are today inappropriately called the Lorentz transformation. Voigt represented his Doppler effect mathematically in terms of space and time variables, whereas the Doppler effect can involve the propagation constant and frequency only. Voigt's unfortunate mathematical representation of his Doppler effect in terms of space and time apparently led Lorentz and others to naively conclude that space and time themselves might actually change in a moving system"

Dear Pretam!

I'm not well informed about your special problem. But I see the possibility of hidden pair production(s) during decay and consecutive reactions.

Maybe some more informations?

My Regards! Hans

Solving range and velocity ambiguities is often accomplished by comparing target data acquired over two, or more PRFs (not pulse widths). A burst of pulses at a fixed PRF may be transmitted and processed within one coherent processing interval (CPI), and then the radar shifts to another CPI on a new PRF; the process may use up between 5 to 9 PRFs in a medium PRF mode (8 PRFs is commonplace), or fewer in low and high PRF pulse Doppler modes. Changing the pulse width in sympathy with the change in PRF enables the radar to operate on the same duty ratio and this has several advantages for the radar. Firstly, a constant duty ratio maintains a constant average power and so the same energy per CPI (assuming equal number of pulses per CPI) and this, in turn, yields a constant detection performance over the various CPIs. Secondly, it may be advantageous to run a high power transmitter at a constant load and so maintain the same average power (if the pulse width didn't change with PRF, the load would vary between CPIs). This is more of a practical engineering point in designing transmitter power supplies. This is perhaps most likely to be the reason why a radar uses several pulse widths but there are other reasons. Changing pulse width to maintain a constant duty ratio brings about a few complications so not all radars will do this.

One of the other reasons for changing the pulse width may be that a shorter pulse is used at shorter ranges (and a longer pulse is used at longer ranges). The shorter pulse has less energy and so a reduced detection performance but this is acceptable at short ranges. Also, a narrower pulse width has a shorter blind range (and close-in eclipsing losses) and this may be important in order to maintain target visibility and minimise the effects of partial eclipsing at very short ranges.

There could be other reasons for using differing pulse widths but the two described above are perhaps the most likely. I could say more if you could tell me more about the radar and its waveforms.

This might help: https://shop.theiet.org/pulse-doppler-radar

Feel free to contact me if I can help further.

Hi Monica. yes.we are using the MCAO model. Our suture is 404156PK5Re Doccol. (@Monica S Spychala)

more in TCD examinations ...

PIV gives average results based on the interrogation window. PDPA gives the instantaneous velocity at a particular point. One can argue about the definition of the point mentioned here. I would say the interrogation window used for PDPA is very small compared to PIV. Moreover, PIV predicts the velocity based on successive frames which sometimes may lead to false values due to several reasons (Choice of the plane, Laser pulse width, the accuracy of cross-correlation program). IF I have to choose one, I would go for PDPA, it is far more reliable and accurate than other methods, provided the lasers are properly aligned and the experiments are performed correctly.

Looks like it is a question in a drill or a quiz. I will not provide the final answer but you can derive the answer from first principals.

- Phase is related to frequency and time (2*pi*f*Dt)

- Doppler shift/spread relation with car velocity and speed of light

- Symbol period duration using the symbol rate provided.

Check chapter 2 in https://pdfs.semanticscholar.org/0dca/6a241ab9d0ca5cdd2746e36b9f6401c780ed.pdf to derive the answer.

good luck!

Hi Andre,

I have read upto 9 pages and glanced more pages. Here are some of my comments.

1. The English is very hard to read, much worse than Charles Dickens whom I thought was the most complex sentencer but you beat him. :-) I also used to do it but I realized the greatness comes in simplicity of expressions and explains our own grasping and its acceptance as popularity.

2. I was made aware of De Broglie's work recently.

3. The Maxwell Wave Model emerged to me in 2008.

4. The orthogonal of three fields, E, M and Space Field (vs Velocity) was with me since Middle School.

5. The 9 Dimensions I have had since 2008. I feel there is a medium that gives momentum to Photon in Space Field. All forces are gradients of the "their substance of fields" in Space. We know Space has e and u. I feel the ether is Space Field, and vibrating in the Space FIeld. It is also a function of temperature, and the gradient of Temp gives rise to the momentum to the photon. The hv in your equation represents the vibration of this, which is related to vibration of B and M and Poynting Vector. I have since 2008, though the model of Vacuum of Space to be Gyropscopic in 9 DImensions. In static they are Gyropscopic but in dynamics, the third field vibrates 2 times faster,

6. The 1/2 hv, 1/2 E and 1/2 M also back my line of thought and I called it Binary Partition of Energy and recently talked about in a draft.

7. The modelling of LC was also there with me in mind seeing parallels with transverse oscillation of B and M fields but it is just a mathematical modelling. And for EMF waves, the helix projected gives rise to that impression. But it is just E and M are chasing each other in dance because of orthogonal relationships. If one is Sin, the other is Cos in the same dimensions, and in other dimensions, one is Cos and the other is Sun. But it does not paint a physical picture of photon.

8. This paper from Richard Gauthier is a good paper to read. Perhaps we all can collaborate on my model of Electron and Positron I had since 2008.

Dear Sunil K Srivastava

It is good to start the discussion by showing the physical interpretation of Doppler equations. A brief and precise abstract to describe this phenomenon is appreciated.

Best regards

The file below has replace the one in the original question.

The first file below is an updated published version of the above. If are interested in the impacts of this look at the other attached files.

The first attached file is an updated published version of the above.

Doppler shifts change observed time because frequency=1/time and the shifts change frequency even in a vacuum. That includes time between observed particles. The second is mathematical proof that all Doppler shifts change observed time based on what happens to a Fourier series when the frequency of each harmonic is multiplied by the same factor K.

Even if the photons travel at same speed the observed time and space was changes by the velocity. That includes the observed time on the light emitter which means the observed rate of photons are emitted. All rates are frequencies and their observed value changes with the closing velocity between the source and observer.

Hi Preston

Einstein's General Theory or Relativity is not even incorrect. It's geometrically invalid.

The general principle of relativity applied to rotation requires that a rotating star drags light. This dragging effect has a velocity component, in that the receding side of a star drags light away from us, and the approaching side drags it towards us.

We can then extend the argument to show that this velocity-dependent dragging effect must also apply when there is no rotation and only simple relative velocity. The back-end of a black hole receding at v has to drag light with it at exactly v, otherwise the light emitted at r=2m that was described as being frozen into the horizon for a stationary observer would either be infalling or exposed for other observers who saw the hole moving. If it's an event horizon, it has to drag 100% to avoid inconsistency, and if its not an event horizon but an apparent horizon, it then also has to drag 100% for other reasons.

So moving strong-gravity bodies have to drag light.

When they drag light, the momentum and energy of that light changes, which means that the relationship between relative velocity and light-energy cannot be that of SR. And if strong-gravity bodies have a Doppler relationship that isn't SR, then all bodies have to share that same non-SR relationship. if we look at a tiny patch of sky containing a distant galaxy, and change our velocity along the viewing path, then everything in that galaxy has to be seen to shift frequency by precisely the the same amount. The same Doppler relationship has to apply to a neutron star as to an isolated atom of interstellar gas. If the neutron star drags light, then so must the atom (and it does, Fizeau effect).

And what's more, the same departure from the SR relationships that we get due to the neutron star's motion must be precisely as the one we get for the atom's motion since we need to be able to explain the same divergence due to dragging on either the star or the atom (principle of relativity), the atom, and the neutorn star and a black hole must all drag light by exactly the same amount at a sufficiently close proximity.

So all matter must be treated as if it is either horizon-bounded, or made from smaller particles that are horizon-bounded. Symmetricality then means that we aren't allowed "mathematical" observers, the only observers that are legal under a full theory of relativity are those made from other light-dragging atoms.

There's then no such thing as flat-spacetime physics - the curved spacetime relativity of a proper general theory of relativity doesn't reduce to SR or to anything else – it is self-contained, and applies right down to the level of particle physics.

The whole idea that a general theory has to reduce to a flat-spacetime physics is something that Einstein just made up (because he wanted his new theory to include his older theory rather than invalidate it), and nobody really questioned whether what he was saying was really true. It satisfied an emotional need of Einstein, but wasn't obviously based on any proper scientific analysis.

People took Einstein's statement at face value, assumed that it was based on research, and didn't do their own investigations.

If you're considering things like precession, then you're overcomplicating: Einstein's GR doesn't even work relativistically for the case of an isolated strong-gravity body far from other masses, coasting in a straight line at constant velocity.

It's a turkey.

A blue shift (if the plasma is the observer) of an incoming electromagnetic wave makes the plasma get greater acceleration from that wave relative to it's reference plane.

Dear Mohammed,

The distance traveled by an electromagnetic wave L = c t where c is the velocity of light and t is the propagation time. If these is an error in the distance then there will be an equivalent error in time dt such that dL=c dt. Accordingly, this will be equivalent to statistical variations of the symbol arrival time. From this simple thinking, one can treat statistical distance errors as statistical delay time in the symbol time. Most probable it will cause statistical delay errors that may cause inter symbol interference.

Frequency offset requires a change in the rate of change of the propagation distance with time.

Best wishes

Dear Mikelis, However I am using PDPA for droplet size characterization, but the cheapest methods which I have seen to be used in the literature are

1) " water sensitive papers"(mostly used in the agricultural field)

2) Image processing (usually shadow-graphy)

Since all the size measurement methods have uncertainties, its suggested to compare and calibrate the result of cheap methods to a more reliable one.

In reply to Di Francesco: The basic equation of the axial Doppler requires things have more than 4 dimensions. Because every thing with an axial Doppler shift has the viewing angle as a dimension or the dimensions and velocity determining the viewing angel. Also I gave on my question a proof that time itself is multidimensional. The axial Doppler shift exists and most the writers on relativity ignore it, because Lorentz assumed the axial effects of aether wind cancel. But Doppler shifts are not aether wind. See the two files below for more details.

Sounds like an interesting idea. I did preliminary work on how to use precision measurements of the ground state in singly and doubly ionised ions in traps to obtain high accuracy values of the hyperfine anomaly over 20 years ago. The idea was to test it for stable isotopes first and then try to implement it for unstable isotopes. There were some interest in G. Werths group, but they could not cool and analyse their test ion sufficiently.

Just to demonstrate that it is possible with precise values would be nice. Even if Y is not the optimal choice.

Send me an email jonas.persson@ntnu.no for further discussions.

With or without relativity, Dr. Cobb pointed out there is a big problem with unstable regions.

But at lest one reference of the Vlasov-Maxwell equations shows relativistic terms in them without the observation angle. By observation angle I mean: the angle between the closing velocity and the line of sight between the observer and the observed. If it takes into axial shift (which should affect mass) that angle would be in it. The error omission of the axial Doppler shift is common to works on relativity, as I pointed out in my paper (the added file, I cannot miss a chance to cite it).

But with or without relativity, Dr. Cobb pointed out there is a big problem with unstable regions.

You can uae this article "Flow rates for milk and cream in pipelines".

Dear Jef,

Thanks again !

zhen

make more testing and used a lot of values of parameters

A spectral line in a plasma fluid medium is broadened by several mechanisms briefly discussed as follows”:

• Natural line broadening: A spectral line width caused by the finite lifetime of ionic excited states in plasmas.

• Doppler broadening: It is developed due to the thermal velocity distribution of the emitting ionic species relative to the absorbing species in rapidly expanding plasmas.

• Electron impact broadening: It is caused by the electron collisional effects and their coupling mechanisms.

• Quasi-static Stark broadening: I is produced by the relatively slowly changing local ionic electrostatic fields (created by nearby ionic species), which split and shift the energy levels of the radiating ions in plasmas.

All these spectral line-broadening effects add up to yield the total line width as a combination of all of them. Usually, only one of these effects unspecifically dominates, depending on the local plasma temperature and density, while the others are regarded as smaller corrections over the dominating one. Thus, there is no simplistic generalization rule for the dominance of the above.

Reference

“ATOMIC PHYSICS IN HOT PLASMAS” by David Salzmann

Thank you Dear Liqun and happy new year.

Dear , Eduard Babulak and Sebastian Zaunseder,

I agree that claiming HR results on heavily compressed MAHNOB or COHFACE databases does not make sense. We did some compression experiments in "

Spetlik, R., Cech, J., Matas, J.: Non-Contact Reflectance Photoplethysmography: Progress, Limitations, and Myths" https://ieeexplore.ieee.org/document/8373904

In that paper, we also comment on the taxonomy of non-contact reflectance PPG methods, so what is meant by the rPPG, iPPG, and other abbreviations really depends on the author :)

We also created a publicly available dataset with uncompressed 4:2:0 videos with ECG ground truth - checkout http://cmp.felk.cvut.cz/~spetlrad/ecg-fitness/

Best regards...

Thank you very much，these articles are very useful for me, and is there any suggestion on the processing of neuclear cross section under extreme high temperature （i.e. 1e7 Kelvin）@ Md. Washim Akram

Unfortunately, I suppose that you published your question too late. Your patient in the sepsis and very probable - septic shock. The extensive surgical debridement along with intensive care and AB treatment was required as emergency intervention 5 days ago. It may be necrotizing or non-necrotizing infection, cellulitis or fasciitis - anyway surgical intervention is indicated. Amputation is an option if patient not improve after debridement (s).

As you know carrier pull-in is required to get the estimate of the carrier frequency, to start the PLL, in real time GPS, this is done through FLL, but in soft receivers it is done similar to acquisition.

usually it is done using large data (4 ~ 20 ms) to minimize or filter out the noise.

A PLL requires better estimate of frequency than provided by the usual acquisition phase, and that is why pull-in is necessary.

Dear Erina

PICMUS Challenge provided a complete in-vivo carotid dataset in two views: longitudinal and cross-section. it can be found in the following sites:

more information about it can be found in the following paper:

" H. Liebgott, A. Rodriguez-Molares, F. Cervenansky, J. A. Jensen and O. Bernard, "Plane-Wave Imaging Challenge in Medical Ultrasound," 2016 IEEE International Ultrasonics Symposium (IUS), Tours, 2016, pp. 1-4. "

regarding to Matlab code , I can help you to progress the segmentation method.

I hope it can be useful.

Regards

Wow!

That would really be appreciated Sarita.

Many many thanks

Hi, Hamada,

I agree 100% with Dr. Schlindwein.

Different ultrasound (US) informations are conveyed depending on US mode, and they are displayed in different imageries patterns. For instance, B-mode represents bidimensional image reconstruction of a physical structure and it is generally displayed in high contrast (BW/grayscale) images. B-mode image reconstruction is typically based on quantifying the incident and reflected energies of an US beam crossing adjacent media with different densities. On the other hand, velocity can be straightforwardly obtained from US signals by taking into account Doppler effect only, and are displayed in a rainbow scale.

Let me ask you what are you looking for when analyzing ultrasound signals?

Peace and blessings!

Dear Kristina,

Following article will help u

Best wishes for u. Good Luck

Dr Saba :)

Except at very low frequencies, pressure broadening can be removed by working at very low pressures. Likewise, Doppler can be eliminated two ways. One is by using effusive atomic or molecular beams. The other is by Lamb dip Spectroscopy.

If there is no friction force at all, how you explain traveling light and bending. Planets form through friction and the must have came from somewhere

First of all thanks to all.. our plasma is thermal expanding plasma confined by magnetic field with background pressure of 1-2 Pascal. We can calculate both jet velocity and temperature from optical emission spectroscopy (OES). Ion thermal velocity was calculated by putting the temperature from OES and jet velocity from doppler shift (for the present case we have not calculated). For your kind convenience I have attached one small OES report.

Dear Yourik,

Sounds like a great research subject. 

If your population is a group of women who have had caesarian section as delivery, you first have to know the landmarks of c-section incision. 

At the moment of pregnancy, it is a very vascular region because of the branches of the uteral arterie supplying the vagina, cervix and uterus itself. The surgeon will try to avoid the vessels for hemorrhage so the vessels stay perfectly intact.

The incision is made through the layers of the abdomen; skin, subcutaneous fat tissue, fascia, abdominal muscles and peritoneum. There is a transverse incision ( not the injure the baby) made through the layers of the uterus.

Referring article: https://sciencing.com/anatomy-associated-cesarean-section-9190.html

The following scar tissue, dense fibrous tissue, is based on the incision that has been made. Normally the incision is made in 'the natural crease', 2 fingers above the symphysis pubis so the scar attends to disappear as it heals. 

More about scar tissue: http://www.activerecoveryboston.com/injury-information-center/general-concepts/scar-tissue/

The increased tension in the area of the fibrous tissue gives a reduction of blood supply. As the internal pudendal arteria is a sensitive arteria, I assume the tension around the Internal Iliacal arteria ( giving the internal pudendal arteria branch) could cause a lower hemodynamic in the internal pudendal artery.

Unfortunately, I do not have any experience with the Doppler Echo device, I hope someone with knowledge and experience can advise you.

maybe a fft to estimate the high low frequency ratio as another indicator?