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Dear Friend and colleagues please share your views on importance of coherence in leadership. How much it justify leadership personality. In absence of coherent approach what draw back leaders face.
Thanks & Regards
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In my work applying negative dialectics to understand how we might better realise an emergent future, I see coherence as the essential link between the present, the adjacent (future) possibilities and the emergent future. Here, leadership has a key role in developing and maintaining that essential coherence. It is leadership that are the custodians of the adjacent possibilities and who must guide our emergence to best effect.
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I want to make two coherent light sources in phase using one laser source. It can be done by using a beam splitter.
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Well, that’s not really possible. The problem is that for any laser the phase wanders randomly over time compared to an absolutely perfect frequency reference. The more stable the frequency and the narrower the line width the slower the wander, but the phase will wander. For two sources to wander around together they have to be tied to the same random walk. That can mean splitting a single source, or it can mean seeding two sources with the same seed laser. It can also mean actively driving the phase of different sources to match that of some reference source. However, in all cases one way or another all outputs are tied back to one reference source.
Now, if you make two independent sources, their phase difference will stay constant for something like whatever the shorter coherence time of the two. However, while you can expect the phase difference to not drift much on time scales short compared to the coherence time, at any given moment you have no idea what that phase difference is and it will wander through all possible values on a time scale long compared to the shorter coherence time. So that lack of knowledge or control of the relative phase prevents you from doing all the things we do with coherent sources. Yes they are coherent for useful lengths of time, but with an unknown and varying phase difference.
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My Awesomest Network, I am starting my Ph.D. studies and I have some questions and doubts concerning it. Could I write them down here, please? First of them is how can I join disciplines as sociology, management, economics, mathematics, informatics and other similar items to make a complex holistic interdisciplinary analysis and coherent study of pointed fields. I think personally that linking or joining et cetera aspects of artificial intelligence and computational social sciences would be interesting area of considerations. What are Your opinions?
Thank You very much for all in advance
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The Aidos-x system is an excellent intelligent system for diagnosing and classifying human diseases. The methods of using the Aidos-x system for diagnosing human diseases are disclosed in lectures with sound "Using automated system-cognitive analysis for the classification of human organ tumors", "Intelligent system for diagnosing early stages of chronic kidney disease", which can be downloaded right now from the website https ://www.patreon.com/user?u=87599532 Creator's title: «Lectures on Electronic Medicine». After subscribing to this site, you will receive databases for medical research to identify the diseases that you will read about in lectures. The acquired skills of working in the Aidos-x system will allow you to apply for grants to carry out scientific research in the field of medicine.
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Thank you.
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I work with an optical coherence tomography system. I want to detect the boundary between two features in an OCT image using a CNN. Kindly guide me to anyone who has done similar work or published work on this problem.
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Actually, there are many tools that you can develop the code. But when we talk about the CNN, it about the long journey of learning. It cannot get on the spot. Maybe you can read some intro what is machine learning, what is deep learning.
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My Awesomest Network, I am starting my Ph.D. studies and I have some questions and doubts concerning it. Could I write them down here, pleaswe? First of them is how can I join disciplines as sociology, management, economics, mathematics, informatics and other similaer items to make a complex holistic interdisciplinary analysis and coherent study of pointed fields.
Thank You very much for all in advance
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Thank You for an opinion!
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Hi everyone!
I'm looking for some exciting analysis methods for correlation, coherence, causality, etc. that can be used for physiological signals (time series, particularly RR time series) obtained from two subjects.
The case study that I consider is: is there any connection between the RR time interval series between a player on the instrument and the listener?
One of the methods that I want to use is the time-frequency coherence analysis by Orini et al. where I will take to input two RR time interval series (from the player and the listener).
What else can I use for this type of data? Do you have any recommendations?
I'm also interested in creating a connection network between players and listeners using the RR time interval series obtained from participants during a music session. However, I don't know what measure for such a graph will be good. It will be nice to create a network like in the Ivanov et al. methodology https://www.nature.com/articles/ncomms1705, not within a body but between the participants. What do you think?
Thank you for every suggestion.
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i am musician and played some instrument like (piano, guitar and flute) and i think about your great idea. if you want to find any relationship between player and listener you must use Pearson correlation analysis but before that you need to convert music elements (like tempo, interval, loudness) to one element with a algorithm then analyze that element with RR intervals of both player and listener. i think if you use Italian classic range of tempo as a score which with rise of tempo score increase (e.g. allegro, andante or something else) and for intervals first utilize major and minor scales as a reference and any passage between scales give a score based on interval changes for easy finding that you can utilize chord changes intervals.
also for data reduction i think you must converts RR intervals to means of RR in a fixed time like 10 sec then calculate music score on that 10 sec and then analyzed correlation of them with two tailed Pearson correlation analysis.
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How can I change the phase coherence of an image with a specific amount?
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The Fourier Transform of an image can be decomposed in two components, its power spectrum (the square modulus of each Fourier coefficient), and the phase (the argument of each Fourier coefficient).
Regards,
Shafagat
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An educational workspace could be a school, university, or any team that works in the education, or training field.
This question addresses particularly t the educational manager but meets also any manager's interests.
Once upon a time, while I attend training about leadership, my mentor said to me: you have to create a team. I thought that I had a team, replied, and he said you don't have a team, you need to build it. At that time, I don't really understand what he meant. And I should continue with a group of coworkers and never had a team. When the team doesn't exist you have to fight for anything as collaboration, outcomes at the right time, sharing experiences, etc After three years, in a new office, I became again a team manager, but I didn't especially create this team, but I think I consolidate the team that I inherited from the circumstances. Nevertheless, I think I gave a good contribution not as large as the executive management who had the power to decide whether to recruit or not the profile that I suggest, but it matters.
So, I would like to get others' experiences to compare and reinforce my experience at work; also writing a scientific article.
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Building team work is a separate subject irrespective of nature of business or office. Education is no exception. In institutes normally subject experts are there. They are in departments .So at departmental level there is need for team work. To be able to work in a team, members have to share common vision or goals of organization , the supervisor or coordinator has to be friendly and cooperative and fair to all . Most often due to different cultural backgrounds and jealousy and rivalry teams cant perform. Ego is a big obstacle. Unless members of tam have clear goals communicated and their is enabling environment created by organization /boss, teams cant't function
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Coherence and correlation seem very similar to each other to me; while, coherence assesses similarity of the signals in frequency space rather than time space. I was wondering whether it is possible to employ coherence instead of correlation in Canonical Correlation Analysis.
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I have the same feelings with you that coherence can be a better criterion for SSVEP decoding. Do you have any progress on the coherence bbased SSVEP decoding? Thanks.
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I need an exemple of the wavelet coherence and cross spectrum please.
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You Welcome, Karim Bouhali
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In text and linguistics, how coherence can be utilised fully? What are the advantages of coherence?
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请你看看中国语言之中的修辞,回环、顶针……接龙,那些都是
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Hi guys,
I am using the negative log likelihood function of a drichilet distribution as my loss function while implementing this paper:
I parameterise the distribution using my network outcome and compute the negative log likelihood of the observed ground truth.
Issue is that I found sometimes the loss is negative, which means that likelihood at the point of observation is greater than 1.
My understanding of this phenomenon comes with two sets:
- This is normal, as likelihood function can be higher 1
- This stands for overfitting, means that the likelihood function probably peaks at the point of the observation so much that other areas of the support would be zero, if we throw an observation there to be test
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I would suggest that you are probably using a poor method of fitting. Please look at the entries on the attached Google search. Good luck David Booth PS I note that R has procedures for doing this fit.
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Hello everyone. Some of us are not experts in psychology but we are interested in the subject and we want to have some basic ideas to help our students. I have some doubts about the similarities and differences between some concepts. I am referring to Dabrowsky's over-excitabilities, Aron's highly sensitive persons, the concept of giftedness itself and the aftermath of post-traumatic stress. There are experts who confuse these terms, deny the validity of some of them, consider them synonymous, etc... I would like to have a coherent explanation as to whether they are related aspects or whether some encompass others. Thank you very much.
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Thanks a lot Béatrice.
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Cold plasma is characterized by a thermal non-equilibrium between heavy particles (ions, meta stables, neutrals) and light particles (electrons),and is characterized by a low current discharge under atmospheric conditions, generated by application of high voltages.While the most common laser output characteristics include: wavelength, gain bandwidth, monochromatic, spatial and temporal profiles, collimation, output power, coherence and polarization.
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Dear Virendra Nath Rai
Thanks you
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Lasers are well known for their coherency. I was wondering to ask whether it is possible to make white light coherent? Of course, a long coherency length the same as lasers is not intended/expected but a coherence length of 10-30 cm.
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Arman Arefi a coherent, continous white light beam is pretty much a self-contradicting statement.
If light is coherent and white, it comes in pulses.
If light is coherent, but does not come in pulses, it is not white.
If light is white and does not come in pulses, it is not coherent.
Pick one.
Note that femtosecond lasers can often have high repetition rates - 70-80MHz, or in special cases even multi-GHz. For some applications, a source with this high repetition rate may work as a quasi-continous source. For others, of course, this may not be the case.
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Assuming there are TWO HeNe coherent laser sources one with LP and the other with Random polarizations (RP). l can see clear fringe pattern if LP light source pass through aligned-fringe pattern MZ interferometer (I had only a LP HeNe laser in my Lab). Is there any difference if take the coherent RP HeNe Laser source for doing the same MZ test? Why?
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Throughout the entire path of the interferometer is light is a collimated plane wave. We can arbitrarily pick two basis polarizations. Let’s choose the two linear polarizations that are S and P at the mirrors of the interferometer. Any other arbitrary state can be described as a supposition of these two. Provided the sample itself is neither a retarder nor a polarizer, the two polarizations do not interfere with each other. Each polarization is effectively a completely independent MZ interferometer experiment. Either polarization produces the same interference pattern. Therefore any superposition of the two polarizations produces the same pattern.
A randomly polarized laser wanders in time over all possible linear combinations of the two polarizations. However, at any instant in time the polarization is well defined. The two paths arriving at the screen are from two slightly different moments in the lasers history depending on the difference in length of the two arms and the path length difference introduced by the sample. For the interferometer to work this path length difference must be less than the coherence length of the laser. It must also be small compared to how quickly the random polarization changes. However those two things are not independent. Since orthogonal polarizations do not interfere, the rate at which the polarization changes is part of what determines the coherence length.
So, basically, if the coherence length is long enough for the interferometer to work, then the polarization state is changing slowly enough to think of the interferometer as being in some particular polarization state at any moment. All superpositions of the eigenpolarizations produce the same interference pattern, so the interferometer works fine with randomly polarized light.
Now, if the sample is birefringent or polarizing, things get more interesting.
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As being an amateur Quantum Optics researcher, I am looking for RG's help with comprehend a few questions re. my fiber Labs.
1. Assuming HeNe laser sources with LP and Random polarizations (RP), let such lights pass through aligned-fringe pattern interferometer (I had only done LP laser). Is there any difference in the TWO sources' output interference patterns? Why?
2. A LP free-space Laser source's MFD and waist get well aligned with a PM fiber coupler (slow axis is in vertical). How and why will the PM fiber coupling ratio (%) be varying with the different polarization incidence angles, e.g. Vertical, Horizontal and Diagonal?
What will be their output characteristics at the PM fiber output end in terms of polarization states?
3. To control a SM fiber output polarization, it can be done by using a fiber-stress type polarization controller. How if I can or cannot control a PM fiber output polarizations by using such controller?
4. How if a typical ED (Erbium-doped) fiber can be used as a CPA (coherent perfect absorber) for certain absorption Laser frequencies?
Or, if one can devise a ED fiber being the exact opposite of the laser process. In turn, make a design what we term a CPA. The ED fiber device perfectly absorbs incoming coherent laser light with given frequency and turns it into some form of internal energy — EM heat or energy.
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The incandescent light source is not considered a coherent source.
This source has a very short coherence time, and you cannot consider it a thermal light though.
another how it could HeNe laser and randomly polarized at the same time!
honestly, I cannot see how could please explain how it is a laser system and randomly polarized.
if you are going to use a thermal light the fringes will be washed-out.
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We synthesized sin waves in matlab. One pair data are at same lower frequency and same lower power. The other pair are at same higher frequency and same higher power. There are high coherence within both lower/higher frequency pair, because they are almost same in the each pair. But if I mix lower/higher frequency/power together and calculate coherence, the higher frequency showed high coherence, but the lower frequency showed low coherence, although the signal in lower freq should be very coherent! I feel something is wrong with power normalization.
The attached is my matlab file. we used mscohere. BTW would wcoherence be different?
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You have to be carful with modelling coherent waves.. you need to begin with certain spectrum width at the start. It will ensure coherence parameters. starting with two or three coherent waves is not correct. there is always a spectrum of few contributing waves. the right way of modelling is spectrum and it’s width.
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I was reading a paper introducing the Delayed Self-Heterodyne Interferometry technique by Okoshi in 1980. It was aimed to measure the linewidth of lasers and the main set-up was something like a Mach-Zehnder interferometer, but one of the arms was delayed by a fiber path much longer than the laser's coherence length, and there was an AOM in the other arm [I don't know if it's important]. The interference of these two beams was claimed to indicate the linewidth of the laser. What I do not understand is that how these uncorrelated beams do interfere?
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For the coherence time the laser’s frequency and phase are stable(ish). Interfering two snippets of the laser from different times, they may have different frequency and phase, but for a coherence time the frequency and phase of each is well defined and they will interfere producing a beat frequency. After a coherence time their phases or frequencies will have drifted enough that the beat frequency and phase drift. However, if the coherence time is longer than your detector bandwidth, you have already recorded the beats that happened during that coherence time. The beat frequency and phase will drift through all possible relations presented by the bandwidth of the laser, but it will all be recorded in the time record.
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Hi,
I'm interested in running periodic ab-initio simulations of a disordered alloy using Quantum Espresso. I noticed that in most recent publications disorder is usually introduced with the coherent potential method (CPA). However I am not really sure how CPA and QE can be coupled together to effectively run the simulations I want.
May I ask you if any of you have already used CPA and QE together and, if so, how can CPA be correctly incorporated in a usual QE routine?
Thanks in advance,
Best,
José
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Many thanks, Abhinav Nag . I will try SPRKKR code
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Hello researchers,
I have around 100 sentinel-1 SLC images. I want to compute coherence between the successive images (1->2, 2->3… and so on). For this, the conventional method is to read images 1 and 2, select swath, apply orbit files, coregister them using the back-geocoding operator, apply ESD and then compute the coherence and the same procedure is also with images 2 and 3, and so on.
I want to discuss another approach here
  1. Read image 1 and coregister all other images (2,3,4…100) with respect to 1.
  2. Now, for images 1 and 2, we can compute the coherence as the above-mentioned method.
  3. For image 2 slv and image 3 slv, we stack them together considering them already coregistered with image 1 and compute coherence.
I want to understand whether it is an ethical way to do it or not.
1. Can we assume in the case of SAR SLC product image 2 and image 3 are also coregistered when they are coregistered with image 1?
2. Do different incident angles affect the coregistration results?
3. Is there any effect of different range and azimuth pixel size? 4. What should be the optimal method to perform successive time series analysis?
Thanks
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I would suggest using isce2 stack processing (https://github.com/isce-framework/isce2).
you may find the tutorials at https://github.com/isce-framework/isce2-docs.
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Dear all,
I conducted a mediation analysis with PROCESS obtaining the following results:
- path a (x on M): significant and negative. Coherent with my theory
- path b (M on Y): significant and positive. Coherent with my theory
- Path c and c': insignificants
Indirect effect: significant and negative.
Is it correct to comment on this result in terms of fully mediation? however, extensive literature defines mediations in which the coefficients of a and b have opposite signs (and/or in which the total effect is not significant) in terms of inconsistent mediation. Should I interpret my results in these Terms even if they are consistent with what I expect?
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بالتوفيق
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I have an EEG dataset that contains 62 databases of 27 subjects, recorded from 32 channels.
how can I compute coherence or correlation of channels (in whole of dataset)?
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Use the ' conv(A,B) ' in MATLAB to calculate the Cross-correlation. A and B are two different signals. Use the ' Y=fft(A,n) ' command to calculate the FFT of a signal. The A is the signal in the time-domain and the Y is the same signal in the frequency-domain. The n is the number of points we want to calculate the FFT.
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Does quantum coherence relate to one particle?
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Despite having the same roots of origin, namely quantum superposition, coherence and entanglement are conceptually different.
For example, coherence can be present in single quantum systems, where entanglement is not well-defined. Entanglement shows a correlation between the pais of photons where changing the spin of one of them will affect their pair photon in a predictible way no matter the how far apart they are, Einsten call this: "spooky action at the distance"
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The Wavelet Coherence Approach has frequently been used in the time-series analysis. How can one apply this technique in MATLAB. Suggestions from expert users are highly appreciated.
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Wavelet Toolbox™ provides apps and functions for analyzing and synthesizing signals and images. You can detect events like anomalies, change points, and transients, and denoise and compress data. Wavelet and other multiscale techniques can be used to analyze data at different time and frequency resolutions and to decompose signals and images into their various components. You can use wavelet techniques to reduce dimensionality and extract discriminating features from signals and images to train machine and deep learning models
Regards,
Shafagat
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If we apply atmospheric correction to the data to enhance the coherence, will it provide accurate deformation result in a densely vegetated mountainous region like the Himalayas.
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Thank you very much for this interesting question. This indeed is a research question that can only be answered after thorough research. While I was searching for some answers, I came across the attached publication. I hope it provides some insights.
Thanks and regards
Gowhar Meraj
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I want to know the calculation for following paper. I am attaching the paper. Please help me
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We are going to use the Heidelberg OCT Spectralis for mouse OCT acquisition. However, we find several papers reporting the use of this instrument for rodents, we are not able to successfully do it. We have two separate devices (1- Heidelberg OCT Spectralis and 2- Heidelberg Hra 2). The Heidelberg OCT Spectralis has two lenses one 30° Standard Objective Lens and an Anterior Segment lens. The Heidelberg Hra 2 has 55° widefield lens. unfortunately, the 55° lens could not be assembled to Heidelberg OCT Spectralis.
As far as we know, given the high dioptre of the mouse eye, we should use the 55° widefield lens. However, using the standard 30° we get a rather acceptable cSLO image, no OCT image is displayed.
Can anyone help solve this problem? We already tried using an additional lens in front of the device lens but still not working, however, maybe the total dioptre of the lens was not enough.
Also, a paper suggests minor software modifications (using Alt+Ctrl+Shift+O in Heidelberg Eye Explorer software) which we could not figure out how that should be done. (Spectral domain optical coherence tomography in mouse models of retinal degeneration. Invest Ophthalmol Vis Sci. 2009 Dec;50(12):5888-95. doi: 10.1167/iovs.09-3724.)
These are some papers about using the Heidelberg OCT Spectralis for rodents:
1- Quantitative Analysis of Mouse Retinal Layers Using Automated Segmentation of Spectral Domain Optical Coherence Tomography Images. Trans. Vis. Sci. Tech. 2015;4(4):9. doi: https://doi.org/10.1167/tvst.4.4.9.
2- Tracking Longitudinal Retinal Changes in Experimental Ocular Hypertension Using the cSLO and Spectral Domain-OCT. Invest. Ophthalmol. Vis. Sci. 2010;51(12):6504-6513. doi: https://doi.org/10.1167/iovs.10-5551.
3- Giannakaki-Zimmermann H, Kokona D, Wolf S, Ebneter A, Zinkernagel MS. Optical Coherence Tomography Angiography in Mice: Comparison with Confocal Scanning Laser Microscopy and Fluorescein Angiography. Transl Vis Sci Technol. 2016 Aug 18;5(4):11. doi: 10.1167/tvst.5.4.11. PMID: 27570710; PMCID: PMC4997887.
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Thank you for sharing the videos. However, I do not get my answer yet. Do you look at the papers I mentioned in the question?
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I normally use the SLC data of sentinel 1 data for calculation of repeat pass coherence. Is there any platform to access InSAR repeat pass Coherence data without needing the original SLC data?
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The Alaska Satellite Facility (ASF) offers a free SAR processing service - Hybrid Pluggable Processing Pipeline (HyP3). HyP3 provides two types of data:
  • Radiometrically Terrain Corrected (RTC) Sentinel-1;
  • Interferometric SAR Sentinel-1 (contains interferogram, coherence and displacement map, among others).
The quota is 250 tasks per month per user.
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It is well known that femtosecond CARS signal can be further enhanced when the condition of electronic resonance with the involved probe pulse is satisfied. Where can I find the relevant formula that quantitatively describe the ehancement ?
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I agree with Pooja Singh.
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The interaction between a two-level system and a coherent field without a cavity does not produce the so-called "collapse and revival". Why?
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Also can be called as entanglement sudden death and birth (when system is entangled) occurs when the system is linked with a channel, cavity, medium or we call it environment.
This channel has some disorders like random motion, thermal instabilities etc which complels the system to loss energy. And we call it the collapse or death. But different environments have different properties, like some show Markovian and some show non-Markovian properties. In the first case, there is a sibgle collapse, because the environment does not has the ability to return the energy or entanglement. In the latter case, the environment releases the energy, entanglement or coherence again to the system and we call it birth of the entanglement or coherence.
The repeatedly exchange between the system and environments causes repeated deaths and births of quantum phenomena, and we call it revival character.
It can be seen readily in quantum cavities or in few of classical environments with static or colored noises
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Globally, air shed management and planning has resulted in viable and constructive solutions to address urban air pollution. Real time monitoring of air pollution based on the data pertaining to the part of the atmosphere that behaves in a coherent manner with respect to dispersion of emission might be critical to comprehend the air quality of a place. I would like to invite a discussion on this aspect of pollutant dispersion.
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I started working on coherence and entanglement. At a point, I became confused between the concepts of entanglement and coherence where an author texted it the same however, they are still considered different by many authors. If anyone can explain, please answer this
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The short answer is, all kinds of quantum correlations satisfy the conditions: quantum coherence ⊇ quantum discord ⊇ quantum entanglement ⊇ quantum steering ⊇ Bell non-locality. Therefore, coherence is considered to be the most general measure.
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The detection was of uv-vis thru a traditional double convex (glass) lens.
Can a parabolic reflecting lens focus and detect RF with this same coating, or stereoscopically 2 parabolics, with sufficient amplification ?
Detection of uv-vis with these metals of low work function is by the photoelectric effect.
But what was the phenomena of Marconi's transatlantic detection of RF (and its associated keyed Morse CODE) by the silver nickel powder "coherer" in the circuit?
Are there electrical component specifications for the coherer (V, I, R). The electrical schematic produced by Google searches shows a DC circuit with an Antenna symbol and other recognizable elements, but the "coherer" is not symbolized but is a 2D sketch of what it actually looked like.
Note: The lay word for parabolic is "dish".
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hi,
The electrical parameter Resistance is the measurable quantity which undergoes changes as the ferrous particles of the coherer are exposed to the impinging electromagnetic field. Even though google may not show any particular details, one can just measure the DC resistance (DC circuit with an antenna) to detect RF signals using coherer. If you use metallic parabolic reflectors and place the coherer at its focal point, the signals will be highly concentrated on it. This will to see the changes in the resistance value relatively with an ease.
Regards
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In GP practice, a balance has to be found between limited time and enabling sufficient mutual understanding. One criterion could be the practitioner's feeling of having understood the subjective logic (world view) of the counterpart. What do we know about such a feeling of practitioners?
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Dear Julius,
Thank you for your answer and for asking me to clarify my question.
First of all, my question refers to the work of family doctors. I am collecting arguments and literature references for updating a recommendation for action by the German Society for General and Family Medicine on the initial interview. The previous version contains the recommendation that in addition to the exploration of the general physical condition, any current complaints, existing risk factors and already manifested chronic diseases as well as the diseases that have already occurred in the family, the current life situation (work, family, housing, etc.) and central aspects of the biography should also be found out. This should be done in order to exclude foreseeable dangerous courses and to develop an overall understanding of the patient, which can guide the development of the relationship and the joint treatment. On the part of the group of authors, we argue that it is worth investing in the beginning - the initial interview - whereas many practitioners argue that in the course of long-term treatment, the relevant life-world-related and biographical data can gradually emerge (" lived anamnesis") or gradually be recovered. In Germany, a maximum of about 20 minutes is available for initial interviews, so the question is when it is "enough". In my experience, information is often collected whose meaning remains unclear from the patient's point of view - does "living in family" mean having social support? Or, in the given case, does it mean quite the opposite, that there is constant tension? Therefore, we thought that "the practitioner's feeling of having understood the patient as a whole person" could be a central criterion. It is clear that this feeling depends on experience and the like, but we assume that it also becomes action-guiding when the practitioner is not aware of it.
Apart from the breadth of possible problem situations, the time frame available for the conversation and the possible long-term relationship as special features of general practice, I think the question can be transferred to other situations.
What do you mean?
All the best
Ottomar
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I read a paper address that "The effect of elastic strain energy is neglected in the model since the precipitation of sigma phase is simulated only in base metals where there is no coherency between austenite/ferrite." I don't understand this, how can we know whether there is coherency between phases? thanks for your answering
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It is not that simple. The boundary is not always incoherent. If the microstructure contains Widmannstatten ferrite, then there is a coherent, or semicoherent boundary between this ferrite and austenite.
The nature of a boundary between phases, of which one is the result of a precipitation process, depends on several factors, primarily on the difference in the free formation energy of both phases, on the grain boundary energies and on the rate of movement of the respective grain boundaries of the precipitated phase.
These physical factors, in case of steel, depend on the composition (carbon content) and the cooling rate.
For a more comprehensive reply and understanding of the physical principles, I suggest to read the book: Phase Transformations in Metals and Alloys, third edition, by D. Porter, K, Easterling and M. Sharif, CRC Press, especially page 299 onward.
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Dear all,
I am performing Wavelet Coherence analysis using R package biwavelet. But as soon as I run the command wtc.t1t2=wtc(t1, t2, nrands=100), I am getting error: Error in arima(d2[, 2], order = c(1, 0, 0)) : non-stationary AR part from CSS.
1. Need guidance to get rid of this error.
2. Is there any limit to the number of observations in the series? (in the above command t1 and t2 have 43 observations each)
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Thanks Iftikhar Yasin for sharing the sample file. TI learned that some data may cause this problem. The wtc function uses another function arima which checks with both coefficients to be between -1 and 1 so that the process would be stationary. If not, it throws the error you are experiencing. This can be solved by using the argument method = "ML" in the arima function itself. The ML stands for maximum likelihood and it forces R to perform the task. For your convenience, I have modified the script and pushed it to my GitHub account. The following link provides a script that you can copy and paste into R for execution. Afterward, instead of wtc, use wtc_Modfd. You can leave the rest as it is. Please let me know if there is any difficulty. Thanks
# Use it as
wt1 = wtc_Modfd(t1, t2, nrands = nrands)
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In a large cohort with MVP comprehensively characterized, MAD at MVP diagnosis was frequent, strongly linked to advanced-myxomatous-degeneration and independently associated with long-term excess-incidence of clinical arrhythmic events.
What is your own experience ? Does your daily practice is coherent with 30% of MAD in MVP? Did you diagnosed MAD without MVP ?
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Ominous sign in Marfan and Loeys–Dietz syndromes (Eur Heart J Cardiovasc Imaging 2021 Aug 14;22(9):1035-1044)
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I am trying to investigate the coherence between two shoulder muscles at 0 - 90Hz. Precious studies used various cuff-off for their band pass filter, e.g. 1–400 Hz(Chen, 2012), 5-300Hz(Boonstra,2008), 3-1000Hz (Kattla, 2010). How do I determine the most appropriate filter for my analysis?
Also, we measured both surface and intramuscular EMG, but some intramuscular EMG signal are not good. Is it acceptable if I downsample the intramuscular EMG of one muscle, and calculate the coherence between it and the surface EMG of another muscle?
Thank you!!
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J. Rafiee
Thanks for your help!
Some of my intramuscular EMG data was 'not good' because the fine-wire slightly moves during muscle contraction. For subjects with more fat at their back, getting a nice recording will also be challenging.
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I want to impute my data set in R by hmisc method, but I am failed as it is not recognizing my file and any command I am applying to impute the data, as I want to impute the whole data set as soon as possible. Is there any easy way for that?
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Muhammad Usman thank you so much , files have been opened
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For thin-film interference, the pulse duration is too short that the a part of the light can't meet the other part due to round-trip delay. In other word, part 1 can't reach the top surface part 2 while it's still lasting at the top surface within the source-on duration.
So if the chopper cut the CW light into pieces and changes the spectrum to a wider spectrum, will that mean temporal coherent length is relevant to pulse duration?
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Michel's last sentence is exactly what I'm referring to in my gas-tube HeNe example. Over the time duration of a single pulse, the light is temporally coherent; however, correlated pulse to pulse (depending on the pulse repetition frequency compared to the coherence time), the light is temporally incoherent.
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In File 7 of ENDF thermal scattering sublibrary, the coherent elastic cross sections of solid polycrystals are all for powdered samples.
Texture in the solid samples will affect the Bragg scattering cross sections. The structural materials in reactors are not powdered samples. I wonder is it reasonable to use the coherent elastic scattering cross section for the powdered polycrystal in the simulation of reactors?
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What do you mean by reactor?
Coherent elastic scattering of what?
Neutrons and X-Rays undergo Bragg scattering in polycrystalline metals.
As you mention the behaviour is similar to a powder, because of low interaction of the radiation with the material.
Nicolò
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How to define coherent "limits" of technology´s in AI ?
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What is your experience about a more effective aid to teaching university students. Some people believe that PPTs help promote focus and coherence of thoughts of the teacher, others feel that the use of blackboard draws better attention of the audience. Of course, we presume that other things are the same in both cases e.g.competence of the teacher/facilitator, relevance of the contents, infrastructure, and motivation level of the students, etc.
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Dear Prof. Saini!
You pointed to an important topic. I think that now during the COVID-19 pandemic online interactive online handouts with video short movies (cases) are the best way to adapt to circumstances (remote learning). Still this problem is a case - and context dependent one:
1) Lorico DS. Lapitan Jr et al. (2021). An effective blended online teaching and learning strategy during the COVID-19 pandemic, Education for Chemical Engineers, Volume 35, (2021), Free access: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847201/pdf/main.pdf
2) A case-study: William Flynn et al. (2021).Delivering online alternatives to the anatomy laboratory: Early experience during the COVID-19 pandemic, Clinical Anatomy, Volume 34, Issue 5, January 2021, Free access: https://onlinelibrary.wiley.com/doi/10.1002/ca.23722?af=R
3) Darius, P.S.H., Gundabattini, E. & Solomon, D.G. A Survey on the Effectiveness of Online Teaching–Learning Methods for University and College Students. J. Inst. Eng. India Ser. B (2021). https://doi.org/10.1007/s40031-021-00581-x Free access:
4) Kumar, P., Saxena, C. & Baber, H. Learner-content interaction in e-learning- the moderating role of perceived harm of COVID-19 in assessing the satisfaction of learners. Smart Learn. Environ. 8, 5 (2021). https://doi.org/10.1186/s40561-021-00149-8 Free access:
Yours sincerely, Bulcsu Szekely
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I now explore three pedagogical strategies to improve junior high school students' skills in ESL academic writing. The main things I set up now are: lexical resources, grammatical range and accuracy, and coherence and cohesion. Do you think it works? Do you have any better suggestions for me?Thanks!
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You can consider with discourse can increase the student motivation and activity to write their idea.
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Why fiber rotator is needed in optical coherence tomography system? Currently I'm building a endoscopic OCT system from scratch and the fiber rotator will be used in the sample arm. Since I'm a newcomer in this area, could anybody offer an explanation for this device?
Thank you.
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Well, I never heard of OCT until this minute, but a fiber rotator is generally for selecting the axis of polarization entering (exiting) a polarization maintaining (PM) fiber. A couple minutes with Google and I see polarization sensitive OCT is a thing, so I think that is the idea. If the light source is polarized, the scattering tissue can change the polarization. Different tissues give different polarization effects, so being able to change what polarization you are observing provides extra tissue differentiation and contrast.
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I'm looking for some kind of study, maybe a survey, that looks at where researchers started their work in terms of ideas and where they ended before publishing it. This could be an idea that they had or a reference that inspired them. It is my belief that researchers often try to tie their initial ideas to their innovative findings in a coherent train of thought before publishing it. But it is also possible that the innovation may have nothing to do with what they started. I wish to check if there is a statistical study on this matter, but I'm not sure what keywords would help me find such a study.
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Hopefully the guidance as per the following publications could help:
  • Blackburn, R. and Welter, F. (2014) From idea to publication: managing the research process, in Fayolle, A. and Wright, M. (eds.) How to get published in the best entrepreneurship journals: A guide to steer your academic career. Cheltenham, UK: Edward Elgar Publishing. Inc., pp. 72-93.
  • Blaxter, L., Hughes, C. and Tight, M. (2006) How to Research. 3rd edn. Berkshire, England: Open University Press, McGraw-Hill Education.
  • Fink, A. G. (2017) How to Conduct Survey: A Step-by-Step Guide. 6th edn. California: SAGE Publications, Inc.
  • Summers, J. O. (2001) Guidelines for Conducting Research and Publishing in Marketing: From Conceptualization Through the Review Process, Journal of the Academy of Marketing Science, 29, 4, pp. 405-415.
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Working on chandrayaan-2 DFSAR data, there are three datasets available:
1) Slant range image data product: The slant range complex image file. Each pixel is represented by two 4-byte floating point value (one 4-byte floating point real and one 4-byte floating point imaginary value). Each pixel in the slant range image is Seleno-tagged with a lat./lon. value.
2) Ground range image data product: The ground range unsigned short int image file. Each pixel is represented by 2-byte unsigned short int. Each pixel in the slant range image is Seleno-tagged with a lat./lon. value.
3) Seleno-referenced image data product: The Map projected image file. Each pixel is represented by 2-byte unsigned short int file(amplitude).
Which should I be using if i want to generate coherency matrix and perform target decomposition?
Thanks in advance!
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Piyush Kumar For generating coherency matrix and further performing target decomposition, Single Look Complex SAR data is required which is Slant Range Data Product. So, in case of Chandrayaan-2 DFSAR data, you need to explore SLI (Single Look Image) data. I think that these basic information are available at ISSDC web portal where you might be downloading data sets.
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I am working in wavelet coherence analysis of two variables and I have plotted the wavelet coherence spectrum. But I wanted to find the phase lag and correlation coefficient for different time periods like 2, 2-4, 4-8,8-16, 116-32. Basically I wanted to decompose the wavelet into different time scales. I am using MATLAB for the analysis and I am pretty new in MATLAB coding. Please help me to find a solution.
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One option could be just using windowing or proper scaling filters and performing wavelet decomposition separately if your ultimate goal is to detect the frequency elements in a particular time period. For this option, you might use any windowing algorithm with or without overlap. Another option could be using different forms of wavelet transform. For instance, wavelet package decomposition might give you more flexibility in terms of time-frequency scaling. You might also wanna look at : Maximal Overlap Discrete Wavelet Package Transform (MODWPT) and Double Density Discrete Wavelet Transform (DWT) for better decomposition options.
For more details:
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Hello,
I am doing SIMULATION of TURBULENT PREMIXED FLAMES of CH4/NH3/air in Ansys Fluent. I am using the following:
Partially Premixed Combustion Model; Chemical Equilibrium; Extended Coherent Flame Model; Energy Eq on; Viscous k-e;
I wanted to try with Flamelet Generated Manifold but don't have CHEMKIN Files for this mixture of fuel.
I have Laminar burning velocity from measurements but don't know where to put it? also equivalence ratio (0.9); In Properties Tab of Species Model Fluent is calculating Laminar Flame Speed - how?
Boundary conditions: velocity: 0.41607m/s; Turb Intensity: 16.64%
Please help!
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Agree, GriMech is one of the best libs to calculate such a problem!
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We calculate coherence as the degree of first-order coherence, defined in Eq. 6, Dudley et al., Rev. Mod. Phys. 78, (2006), where input pulse shot-noise is modeled semi-classically through the addition of a noise seed of one photon per mode. From this model, we expect that the coherence depends on the repetition rate, and the coherence will be higher for a high repetition rate. Is that true from a physical point of view?
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For a prefect pulsed laser, the repetition rate will not affect the first-order coherence. Happenly, I have also worked on this noise model of SC generation several month ago. In fact, I have tried to model several kinds of noise such as the quantum noise, technical noise, as well as the amplified spontaneous emission noise. The last one makes us publish some papers. see " Spontaneous emission noise in mode-locked lasers and frequency combs" and " Tailoring the waveguide dispersion of nonlinear fibers for supercontinuum generation with superior intrapulse coherence ". I also wonder what mathematical models you will adopted for noises?
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Professor Selleri's book "The weak relativity" represents the summary of 20 years of research on the physics of space and time. The research path is clear, the arguments are solid, the logic is evident, the content is revolutionary. If the topics expressed in this book are "true" physics would be completely reversed, the SR and the GR should be abandoned, with all their consequences, such as the Big Bang, dark matter etc .. Yet 9 years after its publication, no one has been able to reasonably contrast Selleri's ideas and in the same way no one has thought it necessary to rethink the physics of space and time .......
Either his ideas are refuted in a coherent and rational way or the physics of space and time must be completely re-founded, there is no alternative in the scientific method, indifference is not an option
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Is there someone who has a research paper?
Preferably for frequencies around 700 Mhz, 868 Mhz, 900 Mhz.
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this pdf>>>>>>
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Do we have any research that scientifically, rigorously or with some level of objectivity measure the structural logic of policies? Or is there anyway measure we use to say that this is a coherent, consistent, congruent policy with integrity (the content)? Or in another way, are there any existing measures one can use to measure the evolution of a policy's causal logic over time?
The existing measure is it also used as an indicator for the potential success of a policy?
Thank you so much
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@Andrew McCulloch
Yes, I agree with the arguments of Hassan as they are fundamentally the bases for policy sciences.
However, I think my interest is in the advancement of the field and the recognition that the structural logic of a policy may have a big impact on the implementation outcomes. Some even suggest that in evaluation one could blame failure more to policy design (noun) than on implementation.
For me, the collaborative approach as suggested by you in concert with mapping as suggested by current research could help objectively or more rigorously analyse the content.
Additionally, for me I think another problem is the "tacit information" or policy elements that we have in policy. They are difficult to trace or rigorously evaluate, and makes policy feedback very difficult. Policy feedback and learning is important to the advancement of policy to include new information to contextualize the policy more to its environment. "Approximating it well against its environment" as suggested by John Peter.
On your starting point suggestion. Yes, that would be a good start. Having identified the data underlying the policy, and relevance (meaning)of the policy. As policy pinching often in 3rd world states tilt toward failure because of the possible mismatch between the policy and its environment. The missing link however, will be the "structural /causal logic"of the policy in Popper's tradition.
That is where my interest to the question comes from, as current scholarship hints at this but doesn't clearly provide methods to evaluate the structural logic.
Thanks,
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We are measuring spectra using Thorlabs OSA which also provides the interferogram signal. We would like to retrieve information about the pulse in the time domain and the pulse coherence.
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Dear Alberto,
the interferogram measured by FTIR-based OSA provides exactly the same information as the usual spectrum. It is impossible to retrieve the pulse shape in time domain using only FTIR interferogram. Very clear and comprehensive discussion of this issue you can find in the book:
R. Trebino, "Frequency-Resolved Optical Gating: The Measurement of Ultrashort Laser Pulses" (Kluwer Academic Publishers 2000).
Particularly relevant chapter of this book you can download from:
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Small Ag precipitate has a coherent interface with Cu, the large one has a semi-coherent interface.
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Thank you!
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I want to find the cross-correlation of the three time series i.e., SST, SSS, and NINO4. Two of those (SST & SSS) have a strong seasonality and the rest one has an interannual cycle. How should I deal with those 3 to find the correlation?
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if you want to measure the interrelation between two signals , it is suggested to use WTC, which is the normalized version of the XWT. Not being normalized, XWT is not altogether a satisfactory method for coherency analysis.
Check out this paper of Maraun and Kurths (2004) on the pitfalls of XWT
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We have conducted an AHP (analytic hierarchy process) to understand experts' opinions of the relative importance of different aspects of natural resource management, specifically for fisheries governance.
From our data, it appears group coherency is low - all our experts have every different opinion about what components of governance are important in the situation we proposed to them.
To confirm this, we want to compute a measure of group coherence as described by Zahir in two papers in 1999. However, this calculation is beyond my statistical abilities. Does anyone have any guide, or ideally code (Python, R script) to calculate this statistic?
Zahir S (1999a). Clusters in a group: Decision making in the vector space formulation of the analytic hierarchy process. European Journal of Operational Research 112: 620-634.
Zahir S (1999b). Geometry of decision making and the vector space formulation of the analytic hierarchy process. European Journal of Operational Research 112: 373-396.
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For this better tool is ANP!
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I have recently begun doctoral research in the field of laser speckle suppression. I want to simulate this effect to provide proof of concept. However, I have no idea where to start. Does anybody have advice on this?
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Dario Ambrosini Thanks for this. However, I am not trying to add speckle to an image. I am trying to simulate the speckle pattern itself (based on the coherence properties of the laser in use). For example, a laser with increased linewidth (due to optical feedback) will have decreased temporal coherence, which directly affects speckle intensity distribution and contrast. The algorithms you mentioned are probably needed (based on statistical copula), however I could not find practical advice on how to actually implement the algorithms. And typically, that is exactly what I need to proceed with simulations!
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When particle size (5um) is greater than the incident wavelength (0.55um) the Mie scattering occurs.The forward scattered light is stronger than the back-scattered light. In literature, it is mentioned that the forward scattered light is exactly in-phase, regardless of separation of dipoles. this is not true for any other direction. The back-scattered light is out of phase.
So, my question is, why forward scattered light is in-phase and back-scattered light is out of phase? If we consider scattering by dipoles, in general the scattering by dipole is coherent. The forward and back-scattered light should be same.
Can anyone explain according to physics (without mathematics) ?
Your cooperation will be highly appreciated. Thanks in advance.
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Basic text books explain mathematically, using the boundary conditions, that light is transmitted through a glass plate without any change in phase at the boundaries. But the reflection from the denser boundary surface to the less dense medium (called external reflection) suffers a Pi phase shift.This is also true for the mechancal oscillation on bound stretched string.
When the surface varies randomly, the reflected or the transmitted wavefront emerges while picking up this random random phase variation. However, the physics of "external reflection" remains the same. The "backward scateering" is "external reflection".
The size of the random surface variations compared to the wavelength determines the detailed quantittative scaterring phenomenon. They could also be isolated particles. But, the basic properties of light transmission and reflection remain the smae.
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I'm trying to check the coherence between a high frequency data and a low frequency data using wavelet.. Is it supported or do I need to convert them to the same nature ..
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I guess Yes, because the Wavelets can be considered as a frequency separation tool...
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There are, of course (correspondingly), "idiotic" Questions. And ridiculous speculations by-analogy (and by-analogy is always suspect). (An example of "Answers" by foundation-less and link-less analogy is " 'quantum' explanations" to several psychological things; it is a bad joke any such person could have a graduate degree !) Sorry: my perception of common things here on RG. And, after years of nonsense, I have decided to state my observation.
It is likely very nearly pointless that I am here on RG (and there have been only so many years I have been able to try to fool myself).
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Questions for the sake of questioning, answers for the sake of answering
I also find that medical issues are being answered by people who have credentials in chemistry, Physics, arts, computer sciences.
Sometimes, the people are discussing matters that are not related the the questions asked and being recommended for such answers.
It could be that most of the medical health care workers are busy in their duties looking after challenging COVID-19 patients and have little time to participate in the discussions on the forum of Researchgate (RG).
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Dear research community.
Can anyone recommend a reasonably priced type of neurofeedback equipment for coherence or ratio training in frontal/midline areas? I am looking for equipment for a pilot-project on children/adolescents and have a very limited budget so want an approach that can give results without needing full LoRETA resolution.
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Please look at the Thought Technology equipment.
Regards,
Rafal
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Let's say I am simulating as simple as BFSK, it has two symbols one entirely on the real plane while other on the complex plane for representing let's say zero and one, that is how the constellation of BFSK looks like. s=data + j*(~data); %Baseband BFSK modulation
Now let's say we added AWGN (N) and Rayleigh fading (h) as well. Rx= h*x + N; Now when I tried to detect it on the receiving side I will have to divide this entire Rx by an h, well that makes sense. My entire graphs for the BER curve match non-coherent detection for FSK. It exactly matched the theory, Eb/N0 vs. BER for BFSK over Rayleigh Channel. Now how to do the same for Non-coherent detection? If I do not divide Rx by h Rx/h, I get a few very very bad results and that doesn't match anything. Theory tells us that In non-coherent detection, prior knowledge of the channel impulse response is not known at the receiver.
In Coherent systems, the receiver needs phase information of the transmitter (the carrier phase) to recover the transmitted data at the receiver side. I haven't used any such thing but still simulation results for BER matched with that of theory for Coherent FSK.
Can someone here help me with this? By not diving by h, will I get better results for Non coherent FSK ? Whether BPSK or BFSK every time we need to divide h*x + N by an h for getting results that match theory.
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"BFSK is done by selecting between two frequencies for each symbol (Binary Frequency Shift Keying). What the OP is showing is samples from M-PSK (Phase Shift Keying); selecting between M phases for each symbol (which would result in two distinct dots on the IQ constellation). Here the two symbols selected are phases 0° and 90°, so these could be 2 of the 4 symbols for QPSK.
To do any form of FSK, the phase must transition over the course of the symbol, given that frequency is by definition the derivative of phase. Thus if one symbol is at a fixed frequency, the phase would vary linearly with time over the duration of that symbol. On an IQ constellation, we would see the phasor rotate at a constant rate from one dot to the next (rotating counter-clockwise to represent a positive frequency and clock-wise to represent a negative frequency).
MSK (Minimum Shift Keying) is the case of the phase rotating ±90° over the symbol duration, as this would be the minimum frequency offset between symbols where the symbols would still be orthogonal. Out of band emissions can be reduced by smoothing the phase from one symbol to the next (generally abrupt transitions in phase or magnitude have high spectral content), which is the intention for GMSK (Gaussian Minimum Shift Keying) where instead of linear phase ramps going up and down according to the symbol used, the phase trajectory is filtered with a Gaussian filter such that the transitions are continuous in the first derivative, meaning the frequency transitions smoothly from one symbol to the next. " Dan Boschen Marcus Müller
Code --
%This program simulates BER of BFSK in AWGN channel%
clear all; close all; clc;
num_bit=100000; %Signal length
max_run=20; %Maximum number of iterations for a single SNR
Eb=1; %Bit energy
SNRdB=0:1:50; %Signal to Noise Ratio (in dB)
SNR=10.^(SNRdB/10);
hand=waitbar(0,'Please Wait....');
for count=1:length(SNR) %Beginning of loop for different SNR
avgError=0;
avgError_awgn=0;
No=Eb/SNR(count); %Calculate noise power from SNR
for run_time=1:max_run %Beginning of loop for different runs
waitbar((((count-1)*max_run)+run_time-1)/(length(SNRdB)*max_run));
Error=0;
Error_awgn=0;
data= round(rand(1,num_bit)); %Generate binary data source
s=data+j*(~data); %Baseband BFSK modulation
NI=sqrt(No/2)*randn(1,num_bit);
NQ=sqrt(No/2)*randn(1,num_bit);
N=NI+j*NQ; %Generate complex AWGN
h = 1/sqrt(2).* (randn(1,num_bit) + j*randn(1,num_bit)); % Rayleigh channel coefficent
Y_with_AWGN = s +N; %Receievd signal with AWGN only
Y=s.*h +N; %Received Signal with both Rayleigh and AWGN
Y= Y./h; %Channel equalization
%---------------------------------------------------------------
%---------------------------------------------------------------
for k=1:num_bit %Decision device taking hard decision and deciding error
Z(k)=real(Y(k))-imag(Y(k)); %Y(k) is actual trasmited signal signal
Z_1(k)=real(Y_with_AWGN(k))-imag(Y_with_AWGN(k));
% if real that mean we chose 1 and if imaginary we chose zero
if ((Z(k)>0 && data(k)==0)||(Z(k)<0 && data(k)==1)) % error conditions
Error_awgn=Error_awgn+1;
end
if ((Z_1(k)>0 && data(k)==0)||(Z_1(k)<0 && data(k)==1)) % error conditions
Error=Error+1;
end
end
Error=Error/num_bit; %Calculate error/bit
avgError=avgError+Error; %Calculate error/bit for different runs
Error_awgn=Error_awgn/num_bit;
avgError_awgn=avgError_awgn+Error_awgn;
end %Termination of loop for different runs
BER_sim(count)=avgError/max_run; %Calculate BER for a particular SNR
BER_sim1(count) =avgError_awgn/max_run;
end %Termination of loop for different SNR
BER_th=(1/2)*erfc(sqrt(SNR/2)); %Calculate analytical BER
close(hand);
semilogy(SNRdB,BER_th,'k'); %Plot BER
hold on
semilogy(SNRdB,BER_sim1,'r--');
hold on
semilogy(SNRdB,BER_sim,'k*');
legend('awgn','Rayleigh');
axis([min(SNRdB) max(SNRdB) 10^(-5) 1]);
grid on;
hold off
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How can we identify the precipitate /matrix relationship (coherent/incoherent) from coffee bean contrast observed in the precipitates.
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Hi Bhavana,
After referring to the attached research article it can be inferred that.
If the precipitates have a coherent strain then they will show a coffee bean contrast in the TEM. Furthermore, in diffraction mode, if the concentric rings are continuous at the interface between the precipitate and the matrix, then it indicates that the precipitates are indeed coherent. Also in this work, in the electron diffraction patterns from (OO1), strong superlattice reflections were observed, which further confirms that the precipitates of A13Sc have an ordered L12 structure. You may refer to the publication for detailed understanding.
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As we face a digital era that connects researchers and researches from around the world there is a tremendous amount of works available for new researchers and their projects and works. Are there any methods, tools, strategies that can improve the bibliographical research stage?
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the internet services data bases are very powerful to obtain any information in the open arena. However, some sites are secure and permission may be obtained from editors and/or those who have published papers there. The academic community is so kind that members may even download some important works and send to you so that your work can be enriched when the publishers permit so.
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I want to write a code to generate coherency volume to detect faults in the data . For that I want literatures to find algorithm and concepts or any type of help in this regard.Thank you .
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Dear Satyendra Panwar:
Coherence is the measures of the similarity of the seismic waveform between traces neighboring or adjacent, and it reveals structural and stratigraphic changes in your data, such as faults, channels, edges of bodies in general. You can measurement the local waveform within a defined space and time aperture or window, by cross correlation of two adjacent traces, both, inline and crossline in 3D seismic data.
It is important to say that there are alternative measures of the similarity of the wavelet or waveform in seismic, such as: cross-correlation, semblance, variance, eigenstructure, gradient structural tensors.
In semblance estimate of coherence, we define the coherence such as the ratio between the energy of average traces in a defined window by the energy of the input traces. It means that you: 1- calculate the energy of input traces, 2- calculate the average wavelet within your window of analysis, 3- estimate coherent traces by their average, and 4- calculate energy of average traces.
In eigenstructure estimate of coherence, we define the coherence such as the ratio between the energy of coherent component traces in a defined window by the energy of the input traces. It means that you: 1- calculate the energy of input traces, 2- calculate the wavelet that best fits the data within your window of analysis, 3- estimate coherent compt of traces, and 4- calculate energy of coherent compt traces.
From coherence volume, you can spatially image and “directly” map faults and fracture systems without the tedious and extremely subjective method of interpreting faults on selected vertical sections, then connecting the interpreted segments to give a complete fault picture. You can more readily understand depositional systems, as the process highlights such depositional features as channels, onlap, turbidite sequences, etc.
It is very important to say to you that the quality of coherence volume attribute results depends on selection of optimum processing parameters specifying such as: dip constraints, vertical and spatial aperture, and processing algorithms.
In addition, before that, you must understand the magnitude of the acquisition seismic footprint, in focus when you working with onshore seismic, because if you do not remove or attenuate this influence, the coherence attribute highlights these changes: often they are the same order of magnitude as your target wavelet distortions related to real geological features, faults or stratigraphic. So, you need, before running the coherence attribute, try to reduce the acquisition footprint by filtering such as spectral whitening and spectral blending / FXY decon / dip enhancement. To better understand subtle fault changes, advanced structural filtering for coherency analysis that use fault preservation and across-fault smoothing techniques depending on the data requirements.
Also, because you use windows following your interesting-horizons, you must check carefully the QC of the input horizons. Sometimes you need to smooth the noisy ones.
Another consideration for your coherence attribute calculation is the fact that there are in most of the commercial software the chance to get almost instantaneously the volume. Also, that with the same input volume, you can modify the computational window options, e.g., direction of the calculus – the best perpendicular to the structural features -, the aperture window, the shape of the aperture window and size or radius, etc.
Try to read the paper attached and this landmark´s ones:
Taner, M. T., et al. 1976. Complex seismic trace analysis. Geophysics. Vol 44 No 6 (June 1979), pp 1041-1063.
Robertson, James D., and Fisher, David A. Complex seismic trace attributes. The Leading Edge, June 1988, pp 22-26.
Marfurt, et al. 1998. 3-D seismic attributes using a semblance-based coherency algorithm. Geophysics, Vol. 63 No 4 (July-August) pp 1150-1165.
Marfurt, et al. 1999. Coherency calculations in the presence of structural dip. Geophysics. Vol 64 No 1 (January-February) pp 104-111.
Best regards Satyendra,
Mario E. Sigismondi
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What type of PCF is ideal for coherent SC generation for carrier envelope offset measurement of a modelocked laser. As far as I know, for coherent SC generation, PCF should be pumped in normal dispersion regime. Moreover, PCF should have ZD (zero dispersion wavelength) close to pump wavelength. Are there any other conditions to consider. Plz advice.
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I'm currently working on a topic modeling project and want to determine the number of latent topics in the dataset. I've recently discovered the UMass coherence score as a suitable proxy. The issue is that I don't know how to calculate it in Stata. Does anyone know an easy way to calculate it in Stata or another program that is easy to use? I've tried to use Mallet without success.
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Hi Addam, in case you found the answer to your question in the meantime, I would be very interested,as I am asking myself the same! Tanks!
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Ionospheric radar it can generate 2D image forming technique my the linear rectangular array Ionosphere radar are recently established at Gadanki (13.5°N, 79.2°E; 6.5°N magnetic latitude) in this Radar is operated in the frequency range 30MHz operation in this are used to finding in the atmospheric layer characteristics coherently Radar imaging technique I have generates In phase and quarter phase IQ data of the Each range bin and each height of the radar and it takes the visibility matrix of each height and each time of NFFT points how is it generates an image of each receiver visibility matrix are to be multiplied are not to the weighing vector
plese give me the solution of this work this RAW DATA are 5 channel receiver database papers of the following are their
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thanks for information Dr. Oleg I. Berngardt
sir,
but in this are only particular region not in the layer of the ionospheric region of E layer echoes data are received in the 5 channel receiver header file data encrypted file is decrypted then generating in the waveforms of both IQ data but the antenna positions and baseline lengths are depending on the received vector of s(t) in the paper of RDplamer spherical coordinate system in our radar station is the not advanced in the ionospheric radar only for x and y-direction of the image generation cartesian coordinate system are used to find ing in the steering vector of the s(t) and direction vector of (W) and it find weight matrix of the antenna in the 5 channel data are their but resolution of the image are very low compare to our base paper in the after generating the IQ data processing the wave it generates image directly one file shows without Fast Fourier Transform, autocorrelation function, and capon algorithm image of the that layer are shown
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The widely used formula for determination of penetration depth from lower critical field is
Hc1 = φln(k)/4πλ^2
which is valid for k>>1, Can anyone help how to find the λ for k~1 material. The mentioned formula does not give any result as the Hc1 4π λ^2 vs λ and φln(k) vs λ curves do not intersect. I know the coherence length from Hc2.
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