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# Harmonics - Science topic

Explore the latest questions and answers in Harmonics, and find Harmonics experts.

Questions related to Harmonics

I'm performing VPT2 calculations in a reaction mechanism to calculate rate coefficients by SCTST theory and perceived that some species presented unexpected negative frequencies after the VPT2 calculation. This was observed for transition structures and reactive intermediates bound by hydrogen bonds or other weak interactions. The example below shows my problem:

Fundamental Bands

-----------------

Mode(n) Status E(harm) E(anharm) Aa(x) Ba(y) Ca(z)

1(1) active 3763.110 3598.689 3.057697 0.123142 0.122807

H 2(1) active 2586.244 2577.498 3.060523 0.122682 0.122379

H 3(1) active 2585.777 2554.772 3.063117 0.122701 0.122411

4(1) active 2557.751 2524.031 3.054464 0.122649 0.122352

5(1) active 2418.710 2039.750 3.069775 0.120913 0.120608

6(1) active 1158.445 1122.073 3.141484 0.122739 0.122411

7(1) active 1150.289 1085.902 3.123672 0.122768 0.122499

8(1) active 1008.896 966.784 3.033002 0.122639 0.122347

H 9(1) active 1007.937 958.193 3.030136 0.122625 0.122394

10(1) active 992.893 899.923 3.068002 0.122841 0.122468

11(1) active 305.153 200.472 3.874636 0.122220 0.121213

12(1) active 277.188 187.185 2.355992 0.122516 0.123005

13(1) active 159.127 -393.075 3.079803 0.118279 0.117974

14(1) active 139.159 -112.063 3.112331 0.124439 0.124194

15(1) active 136.961 -99.655 3.098757 0.124517 0.124199

It is possible to see that the 13-14 modes are negative after the VPT2 procedure, while the harmonic frequencies are all positive. I have read that if the perturbation magnitude is higher than the harmonic frequency, and presents a negative value, it can result in a negative frequency. However, I don't know how to improve the calculation to avoid this error.

I'm will be very grateful if anyone has a clue about this issue or helps me to correct my calculations.

I am designing pseudo-Doppler direction finder and trying to observe Doppler shift, but I am not able to get it. My system consists of 4 antennas shifted by RF switch. Test signal is 433MHz CW.

4 receiving magnetic base monopole antennas are positioned on the disc with 25cm diameter. Switching frequency is 251kHz.

The issue that I unable to see doppler shift at all. As spectrogram shows 433MHz frequency spike isn't showing any shift and doesn't appear to move at all. As I zoom in even with way much smaller RBW no difference. I can see only switching frequency harmonics around my carrier.

As I understand I should see carrier moving around centre frequency as I switching the antennas.

Thank you for your help.

I am currently working on an air compressor unit. I have already done the simulation and testing for modal analysis on the compressor(static condition). Now I want to do a Harmonic response simulation using the imbalance in the rotor because until now I think that is the only parameter that will be causing a harmonic excitation force. but my question is how can I verify the simulation with testing.

Till now I have figured out I can do a vibration test on a running compressor and verify the results. but are there any other tests that I can do to verify the results from simulation?

I am designing a high frequency filter using a loop resonator, one of the main goals is to achieve a reflection loss (S11) of -20db in a bandwidth of at least 500Mhz around 13.5 Ghz.

I used CST studio suite to simulate and design the filter, I used a frequency window of 0 - 20 Ghz at first, and achieved the desired filter (picture 1). I tried to simulate the same filter using a window of 0 - 30 Ghz(picture 2) and observed a harmonic at 27 Ghz, which is natural, but the first peak is now reduced to only -11db, the goal is not achieved. the question is, why is my first peak affected when I only changed the the frequency window ? which one of the two simulations would match measurements in case of a real produced and measured filter ?

I have read 1 article and they said:

1. "frequency analysis calculations to be minima or transition states."

2. "using the gas phase ... harmonic frequencies."

What are those calculation in Gaussian software and what is the input code for those?

Thanks in advance.

We have implemented and installed a grid-connected PV inverter in two different locations. In the first location, it works well, but in the second location, the line voltage to the cubicle body increases and the inverter surge arrester burns. The earth resistance in both cases is below 1 ohm, which indicates that the earthing system is good. I know that high-frequency harmonics are generated by power electronic devices and can cause leakage currents and neutral-earth voltage, but I cannot find the difference between the two conditions. I would appreciate any suggestions you may have.

in the attached pic :

Yellow: line to cubicle body ( which is earthed)

Blue: line-to-line voltage

Green: inverter current

Attached image shows plot of Fast fourier transform of ECG that had applied a lowpass filter to (15 Hz, zero-phase shift FIR with 24 dB/octave roll-off). The frequency bands increase in increments of 0.03125Hz from 0 to 15 Hz. HRV (< 0.4 Hz) and HR (~1.5 Hz) peaks are clear, but I'm unsure what the harmonics are specifically or their significance. I've found suggestions they are related to subtle variations in the PQRST waveform but find very little literature detailing their significance or meaning, besides a preprint Kotriwar, Y., Kachhara, S., Harikrishnan, K. P. & Ambika, G. Higher order spectral analysis of ECG signals.

*arXiv*(2018) doi:10.48550/arxiv.1809.08451.Any advice or further references related to these harmonics and their meaning would be greatly appreciated. Thanks

I have tried to find the discriminant for complex-valued harmonic polynomial by using the following options:

1. Real part of the equation=Imaginary part of the equation=Jacobian with respect to equation=0

2. Using singular method.

The problem is these two methods are too slow to compute the discriminant.

My question is can I have another option to compute the discriminant?

Hi

I did a Frequency analysis in Abaqus. And in next step i create a Modal dynamics to analyse a harmonic pressure which is function of position and time thereafter i used of DLOAD subroutine but my problem is TIME and KINC variables of DLOAD subroutine does not change never and TIME(1) and TIME(2) are equal to "Time increment" of step always and KINC is equal to 1.

Distance x Size + Resonance = Harmonic "SOUND"; as with Earth Sun Moon

@108

#7.83

I have a periodic signal of frequency Fs that is measured, sampled with frequency Fo. How is it possible to recover the shape of the Fs signal, especially if Fo and Fs or their harmonics are close to resonance conditions, when beats effect realized?

I am calculating dynamic hyperpolarizability values for a set of organic derivatives using DFT. I want to plot harmonic light intensity as a function of polarization angle as reported by several authors. How can do this? Please help me.

Regards

Dr. Renjith R

In your experience, how has the alignment or misalignment between strategic thinking and organizational culture impacted an organization's ability to innovate, adapt, and achieve long-term success?

I should experimentally determine the second and third harmonic generation in quantum dot

Hello all:

I have a random signal whose time domain is from 0s to 0.01s. I hope to simplify this signal so that it has the following two characteristics:

1. a infinite time domain

2. a certain funtion which could express this signal

Therefore, I wonder if I could approximate the random signal to the superposition of harmonic signals.

Any information will be appreciated!

published paper on Studying and Mitigating the Effects of Harmonics in HVDC Transmission line Converter

I want to calculate PECD spectra and in order to do so I require calculated electron density in terms of symmetry adopted spherical harmonic basis functions. How should I do that?

what is your opinion about this question?

Thanks

Frequency synthesizers are quite expensive especially for double conversion RF systems. Maybe there are cheaper solutions instead of VCO that might be not such precise. A while ago I was analyzing one repeater that was using RS485 driver for LO. Maybe you have similar experience and can suggest something. For double conversion two individual frequency synthesizers are required or is there any solutions to utilise single one (using) it harmonics or something more exotic. Thank you in advance

How to calculate and design LCL filter for harmonic reduction in matlab simulink?

Hi everyone,

I am trying to place Piezoelectric ceramic patch as strain sensor for substrate structural element. I am confused about the components of the conditioning circuit needed to measure voltage signal induced in the sensor due to harmonic mechanical strain affecting substrate structure . I would be so appreciated if any one illustrated this circuit to me with schematic drawing or pictures from lab setting.

Regards

I'm working on a vibration combined simulation, and I need the different modes of vibration formulation, I've been using harmonic mode but I need further formulation like that.

Any recommendation is greatly appreciated.

Standard tuning for guitar E A D G B E comes around frequently but the old lute tuning E A D G C F is rarely if ever used.

Looking at the gradients, standard tuning is 0 5 5 5 4 5 and the lute tuning is 0 5 5 5 5 5, so the strings in standard span two octaves 0 5 10 15 19 24, while the lute tuning 0 5 10 15 20 25 has one more note than standard.

Same number of points, different number of notes. That makes two different topologies, so we have a collection of guitar topologies that make a theory of guitar.

When guitar strings have one note in common, they have every note in common. Then the guitars have the same set of pitch values (since they can form a union in which every note sounds in tune) but two guitars may have a different number of notes. The notes may be located at different points on guitar.

The number of notes and the number of frets on the guitar is not critical to structure because the structure is basically the same the same with a few more or less but changing the tuning by just one note is critical because it completely changes utility of the structure.

So 0 5 5 5 4 5 is a very, very good number but 0 5 5 5 5 5 is bad number.

It is clear the lute tuning is not as rich as standard because the regularity of 0 5 5 5 5 5 means that the richness of harmonic structures is reduced. For instance, if a major chord moves across the guitar so the tonic falls on successively higher string sets, the structure of the chord in lute tuning does not change. Also, many chords are difficult to play in lute tuning, so a seventh chord is quite difficult to finger. In standard, moving an E chord to the next set of strings makes an A chord, then a D chord; Moving a G chord to higher strings gives a C chord, then F. So standard tuning has 6 different shapes for a major chord, where lute tuning has only one or two.

This shows the principle of least action acts on the guitar topology as a calculus. Action in stardard is far less constrained than lute tuning.

We have here only pitch values, strings, and frets so why isn't that triple a mathematic model?

Perhaps it is this: Mathematicians want to see mathematical proof. But we can hear when pitch is equal, when one pitch is greater or less than another, and when a pitch is multiplied by two.

We know when guitar are in tuning, but we must deduce when they have the same tuning. It would be relatively easy to distinguish guitar in standard and lute tuning, even if they play the same notes. The image of guitar music has the kernal of the tuning.

The topology of music is remarkable because only ordinary math is required to understand the added structure that makes harmony or guitar, but even a brief investigation leads to the realization that the mathematics of music is special and only applies to musical instruments.

I really can't understand why mathematicians and physics are not interested in music as a formal object of study. Doesn't it bug you when you can't understand an everyday object like guitar?

I am working on a trend analysis of at-satellite temperatures (brightness temperature) using Landsat 5, 7 and 8 thermal bands. For the visual and infrared bands I used the sensor harmonization function proposed by Roy et al.

However, for the thermal bands no transformation coefficients were calculated. Is there the necessity to transform the thermal bands?

I am aware of how fundamental frequency of bpf raises. but trying to understand physically causes to excite the harmonics of these fundamental.. this applicable to bearing harmonics, gear mesh harmonics, unbalance harmonics..

1) In utility-scale BESS, is there any minimum clearance requirement (outdoor) from one power conversion system (Inverter) to another PCS?

2) If two PCS requires to be connected on the LV side of one transformer (0.69/33 kV), are there any technical issues/limitations such as harmonic, voltage mismatch, etc?

It would be amazing to know your thoughts on that. Thanks in advance

#BESS

i am working with spectral analyzer (35670a) with noise current amplifier (SR570), however, when i used to experiment about IGZO TFT's low frequency noise, i usually get a 60hz harmonic noise showed in picture.

i just wonder how to eliminate the 60Hz harmonic noise. Also, I will make an individual grounding box and conduct an experiment, but I wonder if this will be effective.

For example, if I would like to calculate thermal conductivity of Si/Ge interface, and I have acquired the second order force constants of Si and Ge. But, How to mapping these force constants to construct dynamical matrix? Is there any code or other learning source?

I could not understand what the meaning of H_t,n or H_t,m is the regular harmonic matrix that links unit cells t and n(or m) because in my opinion, the harmonic matrix is separated for each single cell., how can it link unit cells?

I'm essentially looking at creating a 4 body harmonic potential where the stiffness constant can be represented as a stiffness matrix such as to allow for the direct dependency of one atom on the movement of all other atoms defined in the quartet.

In the VIV process of a cylinder or a bridge, we can always find harmonic frequencies in the flow field. How does the harmonic frequency come into being and what does it mean? What does the harmonic frequencies represent and what effects can it bring?

Dear Researchers,

I am looking for methods to mesh a twisted blade in order to get more structure mesh.

I tried several mesh size yet the quality metric are a bit bad.

I am analyzing regarding the skewness and the orthogonal quality.

My objective will be performing modal and harmonic in order to determine the stress distribution adequate to the natural frequencies.

Thanks in advance for your advise.

Dear all,

I am trying to perform harmonic analysis with the forcing term which is not harmonic but periodic. I converted the forcing term to harmonic series of sine and cosine. Now the problem arises when I have to incorporate this force in ANSYS analysis.

Is there any way to input non harmonic forcing term, or the another way to input series of sine and cosine term ??

I am currently working on my project of crack detection in cantilever beams using an Ansys, and I did modal analysis and harmonic response to find the natural frequencies and frequency response of the deformation.

I have found the maximum amplitude of all 6 modes and how does it really work in crack detection?

amplitude gets lower when frequencies get higher.?

I am trying to solve an isolator suspension problem in which a mass is suspended using 4 Nos of 3D springs(Isolators). I want to carryout response studies to find harmonic and random response on mass.

I tried using bushing element in ANSYS mechanical. Here in connections I have provided relevant stiffness and damping in matrix form for bushing elements.

Also overall damping ratio of 0.02 % is given as input under harmonic analysis tab.

Analysis shows that response is function only of harmonic damping ratio not one given in bushing element . Can anyone pls comment on this?

hello everyone

i'm asking about any mathmatical methode that can calculate the(total harmonic distortion) for ramp function ?

Does anyone have access to any of these articles? I have already tried to contact some of the authors, but without success. I don´t speak Mandarin so is very difficult with CNKI where they are available through payment. I can not understand even the payment method or if I would have access from Brazil. Thanks in advance for any help.

P.S. Even with google translator it was impossible understand the database.

**1. DC Bias and Saturation Protection of Converter Transformer**

WEN Ji-feng,ZHANG Xiao-yu,CHENG Xiao,XIONG Hui,LI Hai-ying,CHEN Song-lin(Nanjing NARI-relays Electric Co.Ltd.,Nanjing 211102,China)

This paper analyzes main causes of DC bias of converter transformer,and summarizes electrical characteristics of exciting current during DC bias of converter transformer and the mechanism of DC bias leading to damage of converter transformer.In addition,the principle of saturation protection of converter transformer and the implement method of the protection are introduced.Finally,points for attention in the engineering application of overexcitation protection of converter transformer are discussed.

**2. Analysis on maintenance and operation of earth electrode shared by some HVDC systems**

Lei X.,China Electric Power Research Institute | Li X.,China Electric Power Research Institute | Lin S.,China Electric Power Research Institute | Sun X.,China Electric Power Research Institute | And 4 more authors.

Dianwang Jishu/Power System Technology | Year: 2015

There are many inconveniences of maintenance and operation for HVDC systems with sharing earth electrode. When earth electrode line maintenance is implementing, personal security may be at risk because of DC current flowing through earth electrode line. As an example of sharing earth electrode of two HVDC systems, DC current distributions of earth electrode line and effect factors were analyzed according theoretical analysis and the actual project parameters. And operation suggestions of HVDC systems were proposed during earth electrode line maintenance. The results show that DC current distributions of earth electrode line are mainly affected by earth electrode resistance, earth electrode line resistance, maintenance grounding location and soil conditions. Besides, DC bias of converter transformers may be affected by DC current from earth electrode line, in serious condition, HVDC systems are blocked because of saturation protection action of converter transformer. © 2015, Power System Technology Press. All right reserved.

**3. Analysis on the Transformer Saturation Protection in Fengxian Converter Station**

LI Yueting,HAO Yuedong,LI Tengliang(Shanghai Management Office,Grid Operation Branch of State Grid Corporation of China,Shanghai 201413,China)

Fengxian Station is the receiving end of ± 800 kV Xiangjiaba–Shanghai UHVDC transmission project,and the transformer DC saturation protection(TSP) in the station has alarmed and even triped under the unbalanced operation mode while the transformer was charged.This paper introduces the operation principle of TSP,and analyzes its action logic and the rationality of its settings,and then discusses the cause of leading to TSP maloperation and related solution for the manufacturer.

**4. The Influence of DC Bias and Harmonic on Sympathetic Inrush of Converter Transformer**

Lingfeng Xia;Xiangfei Sun;Junwei He;Jianping Zhou;Kunming University of Science and Technology;

Compared with common transformer, converter transformer shows some differences from the perspectives of DC bias and harmonic and so on, which has significant influences on sympathetic inrush. There are few researches about that. Therefore, taking the characteristics of converter transformer as the starting point, this thesis analyzes the influence of DC bias and harmonic on sympathetic inrush of converter transformer. Emulation proof is processed with utilization of PSCAD/EMTDC and MATLAB. It's found by study that the influences of DC bias on sympathetic inrush mainly depend on its relationship with the direction of the magnetic linkage of transformer. Content of characteristic harmonic in sympathetic inrush is relatively high and the content of each subharmonic has linear correlation with the intensity of DC bias.

Using Quantum espresso I was able to converge through SCF calculation for my structure. I have also optimized the geometry by vc-relax. Now I want to fit forcefield parameters for bond, angle, torsion, improper, non bonded Buckingham/coul potentials. How can I do so?

Hello World,

I am trying to perform the modal analysis and harmonic response analysis for forced vibration in rotating cantilever beam through ANSYS. Is there any way to incorporate the rotational velocity and add Coriolis and centrifugal effect for the analysis?

Hi there, I am running a targeted molecular dynamics job on NAMD and an error occurs, FATAL ERROR: Number of atoms in constraint constant PDB doesn't match coordinate PDB ,

in the procedure of minimization that I can't fix. it doesn't progress any further than making the "harmonic restraint" pdb. so, has any one ever encountered this error ?

I am trying to simulate harmonic dynamic loading applied on square machine foundation using

**ABAQUS**. While doing experiment, I have used rotating mass type mechanical oscillator. The loading intensity of the same is dependent on the angular frequency(w), [**F(t) = F_0.Sinwt = m_e.w^2.Sinwt**]. In the numerical modeling, to apply the load on the footing I need to convert the load in terms of**real**and**imaginary**components. I am quite confused, how to do that. Can anyone explain, how to calculate the real and imaginary components of the dynamic load. I have mentioned the variation of force amplitude with the rotating frequency of the mechanical oscillator.Hello all,

I want some recommendations for spectrometers of UV to near IR (230 nm to 900 nm), with High resolution, have a good price, can distinguish between second and third harmonic, and are easy to use.

Thank you.

SNS is a feeding tube device provides babies supplemental feeding , it helps in inducing and maintaining lactation by triggering harmonal release. Any practical experience about the nursing system?

I have been trying to get a sub synchronous resonance scenario in the "Wind Farm - Detailed DFIG Model (available on mathworks website)" in Simulink as a part of my project. For that I have to identify the possible frequencies where the harmonics can occur. To identify these, an impedance scan/frequency sweep of the wind farm is required to understand. I have been trying to get give input perturbations to source voltage, measuring the ouput changes at windfarm terminals and then using script to calculate the Fourier Transform. But the results are not ok as my impedance scan actually shows lower impedance at higher frequencies.

Is there any other way to get an impedance scan for the wind farm in Simulink?

I understand there will be exact multiple of fundamental frequency based bearing rotation with respect to fundamental, based on gear rotation with respect to fundamental. But what exactly means for multiples of bearing rotations, multiples of blade passes like 1x, 2x, 3x etc.,

Greetings,

I have modeled a faulty system (Bowed rotor) in MATLAB. By increasing the sampling frequency, a frequency component appeared in the FFT graph (after the 1X), but the location (frequency in which the component appeared) is constant, i.e., by changing the system's angular velocity, the coordinate of the X-axis (frequency) is constant and does not show a harmonic component (such as 2X or 3X) while the fault has been modeled as a harmonic force. On the other hand, by increasing defect severity the amplitude of this harmonic component has been raised. Now, does anybody know and could explain it physically, please.

Yours sincere,

In the context of designig a VAR compensation system with switched capcitors and a TCR, due to the switching of these two components there will be harmonics introduced to the network, the in order to supress those harmonics one must use harmonic filters, but, ¿is it necessary to take in count the power consumption of those filters in order to calculate the size in VAr of the capacitor bank and reactor ?

Hello everyone, I am analyzing the harmonic response of a beam in ANSYS workbench and I need to assign the loss factor (hysterisis or structural damping) to the beam I am studying . My question is is it possible, in my case, to add the following APDL command (MP,DMPS,MATID,0.01) below the object in the geometry branch?

Can anyone help me to write review article on harmonization topic ..special reference to India.....means giving outline ..which topic should be covered under this head..please help me..i think this topic should be address.

Hello everybody

Is there any software other than Matlab to produce data for sinusoidal excitation with gradually increasing amplitude like attached plots?

Thanks

The stress strain curve of rubber is not linear and follows a curved line both as the strain increases and as it decreases again. Does this hysteresis lead to formation of harmonics or other non lienar phenomena in eg a vibration insulated system?

What are the challenges and update s regarding harmonization among food safety rules in india and worldwide.

Kindly suggest articles and reviews.

Hello everyone, I am analyzing the harmonic response of a beam in a frequency range [0-50 Hz] but I noticed that the results for the 0 Hz frequency are not provided by ANSYS workbench. would like to know is there a possibility to have the amplitude of the displacement of the beam for the frequency 0Hz?

Hello all, i'm trying to analyse the vertical deflection of a beam traversed by a point load as shown in the figure. The load has the following format: F=Pcos( ωt+ϕ) where P is the load amplitude (N), ω is the radial frequency of the applied load (rad/sec), V is the speed of the moving load (m/s) and t is the time (s). ϕ is an initial phase applied to the load to ensure that for every frequency, it will arrive at the mid-span with maximum amplitude. Please guide me, how would I define that in Ansys workbench?

Thank you.

I am doing vibrational analysis of mono-acetic acid after wavefunction and geometry optimisation. In the output file of vibrational analysis the following lines were present containing harmonic frequencies of mono-acetic acid.

****************************************************************

HARMONIC FREQUENCIES [cm**-1]:

-93.9446 -56.8345 -14.9036 79.1124

83.2432 123.7967 180.8622 415.9833

465.7580 564.8411 581.9038 795.9969

942.4123 1030.7040 1139.4888 1218.9753

1356.8784 1433.9457 1447.8727 1776.4078

2976.9823 3023.5483 3084.8354 3634.5117

PURIFICATION OF DYNAMICAL MATRIX

****************************************************************

HARMONIC FREQUENCIES [cm**-1]:

-55.0883 -0.0000 0.0000 0.0000

80.2766 101.0671 159.3476 415.9277

465.5977 564.8100 581.8316 795.9872

942.4062 1030.6968 1139.4801 1218.9731

1356.8769 1433.9456 1447.8725 1776.4022

2976.9823 3023.5483 3084.8354 3634.5117

ChkSum(FREQ) = 0.26286465E+05

Can some one help me understand what is meant by "Purification OF DYNAMICAL MATRIX" and interpret the above results CH

_{3}COOH should have 18 modes of vibrations (3N-6). but I am getting 20 modes of vibrations? Furthermore is -55.0883 cm^{-1}a false flag or is it because of incorrect optimisation of structure?Application of these 3 Means (AM, GM and HM) individuality? where can we use this? welcome with research papers?

its like,why does the power system network still affected by effects of harmonics yet mitigation measure in place.

thanks

Hello,

I am working on project that consists of analyzing power quality. The grid is connected to a nonlinear load which will evidently causes appearance of harmonics and potential swell and sag on the wave form of load current.

Basically, the measured voltage and current will be processed to determine and detect any possible disturbances, for instance swell and sag .

I am asking for an algorithm to do so(especially for sag/swell).

Thank you.

Hi

Sir how is useful in power electronic system for measure harmonic is MATLAB or PLECS

i used CHARMM-GUI membrane builder module to prepare the necessary files for simulating a membrane using NAMD and while inspecting the configuration input files, i noticed that it uses collective variables (ColVar) to apply a harmonic potential on some atoms of the head groups of the lipids during equilibration only. why would i need to apply these potentials? and why selecting the centers values to be of these specific values (ex: 18 for the cholesterol lipid)?

these are the first and last colvar lines included in the first equilibration step:

###Lipid Head###

Colvarstrajfrequency 100

Colvarsrestartfrequency 100

colvar {

name chl1_head_upper

distanceZ {

ref {

dummyAtom ( 0.000, 0.000, 0.000 )

}

main {

atomsFile restraints/chl1_head_upper.ref

atomsCol B

atomsColValue 1.0

}

}

}

harmonic {

colvars chl1_head_upper

centers 18

forceConstant 5

}

....

....

....

colvar {

name psm_head_lower

distanceZ {

ref {

dummyAtom ( 0.000, 0.000, 0.000 )

}

main {

atomsFile restraints/psm_head_lower.ref

atomsCol B

atomsColValue 1.0

}

}

}

harmonic {

colvars psm_head_lower

centers -21

forceConstant 5

}

Please suggest any algorithm diagram for understanding the concept of an active power filter for removing harmonics.

Hello,

I have a circular loop absorber with two dielectric substrates. I want to reduce the reflection at 3GHz. When i set the circumference to half of the effective wavelength, I got this simulation result.

My equation is why the second resonance is obtained at 12 GHz instead of the 2nd harmonic (6GHz)? And why is the reflection coefficient at 12 GHz smaller than at 3 GHz?!

In the attached file, the harmonic-like sequence is defined. Is this kind of a sequence known in the literature? Do you know any source with the properties of such numbers?

Dear Lammps users, a vaste literature is available on the matter of molecular mechanics simulations of layers, “slabs”so to say, of different materials floating on each other. Typical examples are layers or bilayers of lipids on water.

In the final simulation, more often than not we may find a central water slab with two molecular layers symmetrically disposed adjacent to the opposite surfaces of the water slab, so, for example, the disposition in, let’s say the z direction, is “molecular layer A” – “water slab” – “molecular layer A”

Additionally, two empty spaces are added on top (and below) the molecular layers to avoid mutual interactions between the molecules of the layers. I forgot to clarify that the system is periodic in all 3 directions.

Layers are usually “built” alone and equilibrated (with either fix NVT or NPT) and subsequently combined to give rise to the above described system, which is then submitted to the desired simulation.

I tried several times to follow this procedure and the major issue was to avoid to have images conflict which immediately stops the simulation rising an error.

I found a trick which consists of preparing the water and organic molecules slabs separately by using fix addforce to constrain the molecules (water and organic) of each box inside a relatively narrow layer. This system is somehow equilibrated with fix NVT.

In a second step, with a specific program I wrote, the complete system A-water-A is submitted to simulation.

Actually, the simulation finally runs, even if I am getting an “inconsistent image flags warning” .

Honestly, I feel uneasy with my “trick”. It seems to me unphysical and I doubt that the authors in literature made use of such a cumbersome procedure.

I hope to find some “ultra-patient” and competent gentleman willing to comment on this.

My field of research is the regular synthesis of 2-dimensional polymers at the liquid-air interface.

MD simulations are an essential tool in my research.

Thanks a lot for your attention

Paolo Botto

p.s. herebelow please find the Lammps input script of a “toy” system of 16 molecules:

# LAMMPS INPUT SCRIPT M44 16 filename: in-M44-16-00

units real

boundary p p p

atom_style full

pair_style lj/cut/coul/cut 10 12

bond_style harmonic

angle_style harmonic

dihedral_style opls

improper_style cvff

atom_modify map array

pair_modify table 0

read_data lamdata-M44-16-00

velocity all create 300 887723

fix mynve all nve

fix mylange all langevin 300 300 100 314159

group mygroup type 2 4 # force acts on Oxygen and Nitrogen only

region myregion1 block 1.0 10.0 -42.0 42.0 -42.0 42.0

fix myforce 1 mygroup addforce -1.0 0.0 0.0 region myregion1

region myregion2 block -10.0 -1.0 -42.0 42.0 -42.0 42.0

fix myforce2 mygroup addforce 1.0 0.0 0.0 region myregion2

neighbor 2 bin

neigh_modify delay 0 every 1 check yes page 100000 one 10000

thermo 1000 thermo_style custom cpu step etotal temp press density dump mydump all custom 1000 dump-M44-16-00 id type mol xs ys zs

restart 1000 rest1 rest2 run 500000

write_data dat-M44-16-00 write_restart restart-M44-16-00

I have completed the simulation of grid tied inverter and got voltage, current, harmonics distortion at PCC but i don't know how to extract features and process the simulation outputs for SVM training and classification in MATLAB

Goldbach and Euler’s proof is a typical example of what some historians consider a misuse of divergent series , for it starts by assigning a “value” to the harmonic series ∑1/n and proceeds by manipulating it by substraction and replacement of other series until the desired result is reached.

Is there a definitive way to determine the delay between the fundamental (800 nm) and it's second harmonic (400 nm) generated by a type 1 BBO?

Our Ti-Sapphire laser generates 800 nm pulses at 30 fs, a Mach–Zehnder interferometer is constructed. One arm is made to pass through a type 1 beta-BBO of 100 microns, while the other is not disturbed. The delay between 800 and 800 nm was determined quite easily before the type-1 BBO was placed, but a delay is introduced between the 800 and 400 nm pulses in one arm due to the type-1 BBO. Is there any way to determine the delay between them?

PS: The THG generation method was not advisable since control of individual intensities was not guaranteed in the said method.

Greetings all. I am writing an input file for my simulation but I get error on the improper_style. I used opls force field so I used 'harmonic' style for it. But, it gives out error like so:

*ERROR: Incorrect args for improper coefficients (src/MOLECULE/improper_harmonic.cpp:219)*Does anyone know where it went wrong or how to fix this?

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