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# Harmonics - Science topic

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

Questions related to Harmonics

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 ?

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?

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 was looking into audio classification using handcrafted features fed into an artificial neural network.

**Here is a list of features that I could collect so far**

**Time-domain features:**

Zero-crossing rate

energy

energy entropy

RMS value

**Frequency domain features:**

spectral centroid

spectral entropy

spectral flux

spectral roll-off

Mel frequency cepstral coefficients (MFCC),

harmonic ratio

Fundamental frequency

Chroma vector

Are there more features available? I would also like to know if there is a single tool to extract them all

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

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.

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

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?

the @GLEONetwork #Zooplankton as Indicators Group #ZIG needs your help! We will harmonize zoop #data from #lakes globally & we still have a lot of white space! If you think your data can help, here’s our big project & DM if you have questions!

We’re so excited to have the support of 73 (!) #ZIG members already, but the more, the #data merrier! If you know of any #notwitter #zooplankton people who may be interested in joining the project, feel free to reach out and send information along! #PlanktonAreAwesome

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.

Let me consider harmonic oscillations x'' + x = f_t(t), where f_t(t) describes thermal stochastic force <f_t(t) f_t(t')> \sim \delta(t - t'). I have already understood, that I can switch from such differential equation to the integral equations, where the integrals can be performed in Ito or Stratanovich sense. Which one relates to the real situation?

Another case: escape probability. If I want to numerically extract mean lifetime of a classical particle in a potential well due to thermal fluctuations, what kind of stochastic modeling should I use?

Eigen energies of Hydrogen atom, treated as a central force problem, can be derived with Bohr model. Given the basic nature of the harmonic oscillator problem, it is a bit surprising why its solution may not exist in old quantum theory.

I am trying to expand an explicit piecewise equation as a Fourier series formulation using Wolfram Mathematica software.

An example of these expansions is depicted in this paper ( ).

The two piecewise multi-parameter equations (eq. 12 & 13) are transformed into two Fourier series equations (eq. 14 & 15).

What is the best way to go about performing this expansion and how?

I am trying to reproduce a paper which has followed a simulated annealing procedure with a simultaneous decrease in harmonic force constant.

a) Starts at 60 K, force constant = 5.0 x 10

^{4}kJ/(mol nm^{2})b) After 20 ps, temp = 120 K, force constant = 2.5 x 10

^{4}kJ/(mol nm^{2})c) After 40 ps, temp = 180 K, force constant = 1.25 x 10

^{4}kJ/(mol nm^{2})d) After 60 ps, temp = 240 K, force constant = 0.6 x 10

^{4}kJ/(mol nm^{2})e) After 80 ps, temp = 300 K, force constant = 0.3 x 10

^{4}kJ/(mol nm^{2})d) After 100 ps, NPT step with 1 bar pressure, followed by production run.

Is there a way to automate this in a single mdp file? I understand how to perform simulated annealing using the nvt.mdp file, but how can I use a different posre.itp file (with the appropriate force constant) for each step of the annealing? Any suggestions would be really helpful.

Hello dear

There is a significant variation between official statistics of FAO, NRCS, and HWSD about the amount of global SOC over 0-100 cm depth of soils around the world. all of them have studied same areas of lands with almost same methods and even more, they shared database with each other. For example, one of the main resources of HWSD to calculate global SOC comes from FAO. However, there is a considerable difference between them:

total global SOC over 0-100 cm depth:

HWSD: 2469 Pg

NRCS: 1399 Pg

FAO: 1459 Pg

references:

1- Hiederer, R. and M. Köchy1 (2011) Global Soil Organic Carbon Estimates and the Harmonized World Soil Database. EUR 25225 EN. Publications Office of the European Union.79pp

2- Hiederer, R. Kochy, M. 2012. Global Soil Organic Carbon Estimates and the Harmonized World Soil Database. EUR Scientific and Technical Research series â€ “ISSN 1831-9424 (online), ISSN 1018-5593 (print), ISBN 978-92-79-23108-7, doi:10.2788/1326.

3- 1. Köchy, M. Hiederer, R. Freibauer, A. 2015. Global distribution of soil organic carbon – Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world. SOIL, 1: 351–365. http://www.soil-journal.net/1/351/2015/

I'd like to discuss the question of the Role of Digital Shadows and Digital Triggers in the Digital Twin Concept. I think both terms play an important rule but they are not exactly defined til now.

You can see my point of view about in an attached poster for an order-oriented Digital Control Twin.

The Digital Shadow (DS) is only a Snapshot of a real object at a certain time, a certain location and for a certain 'cutout' that represents the actual state but not the entire object itself. To interpretate the DS it is very important therefor to define the exact time, location and cutout of the DS. and to store this data.

The Digital Trigger (DT) is only an impuls of the virtual twin at a certain time, location etc., to 'influence' the real twin but it is not the entire virtual twin itself.

The virtual and real twin are connected by a certain kind of regulator to detect and evaluate deviations of DS and DT and to harmonize them. The kind of regulation can be very different and depends on the object itself, the environment and the purpose.

- Hello everyone, I have trouble getting a graph like this in ansys? The horizontal axis represents the x- coordinate and the vertical axis shows x axis displacement. Can anybody help? I can’t found this function in harmonic response.Thanks a lot.

I have a nonlinear ODE (second order) and exponential force in right side of equation ( q(t)=p

_{0}(1-t/t_{0})EXP[(-r*t)/t_{0}] ) . p_{0}, t_{0}and r are constant. I see in Nayfeh and Mook book only harmonic force. but i have a exponential force. How I can use from the Method of multiple scale to solve this problem?The Van der Pol oscillator can be give in state model form as follows:

dx/dt = y

dy/dt = mu (1 - x^2) y - x,

where mu is a scalar parameter.

When mu = 0, the Van der Pol oscillator has simple harmonic motion. Its behavior is well-known.

When mu > 0, the Van der Pol oscillator has a stable limit cycle (with Hopf bifurcation).

While we can show the existence of a stable limit cycle with a MATLAB / SCILAB plot with some initial conditions and some positive value for mu like mu = 0.1 or 0.5 (for simulation), I like to know if there is a smart analytical proof (without any simulation) showing the existence of a limit cycle.

Specifically I like to know - is there any energy function V having time-derivative equal to zero along the trajectories of Van der Pol oscillator? Is there some smart calculation showing the existence of a stable limit cycle..

I am interested in knowing this - your help on my query is most welcome. Thanks!

Hello,

I have a question regarding the zero-sequence voltage injection in three-phase SSTs with bypassed modules in a failure case. I investigated some literature and it is clear that only the fundamental harmonic can shift power between the 3 arms (for power balance).

A 3rd harmonic is often used to reduce the peak arm voltages (-13.4%). However, I investigated asymmetrical fault cases and a 5th and 7th harmonic can help tofurther reduce the arm voltage by a small percentage like 5% (so less redundant modules are needed):

Conference Paper Adaptive Zero-Sequence Voltage Injection for Modular Solid-S...

My question is: Do you know other methods to handle asymmetrical fault conditions in cascaded H-bridges or SSTs? Can I handle grid-imbalances like module faults, since the modules in the phase with an over-voltage have to transmit more power (if no zero-voltage injection takes place)?

I thank you for your suggestions and ideas.

Hi all,

Are there any standard benchmark power systems for harmonic power flow studies approved by organizations such as IEEE, IEC, etc or widely used by researchers to compare their methods?

Many thanks in advance for any hints or answers.

No matter what laser we use, or what sample we use (even if we use no sample) we are getting a peak at 804 nm, which is 12,437 cm-1 and a Raman shift of 6359 cm-1, if using the 532 laser. We are not sure if it's a harmonic, because its not an integer multiple. It is around 1.5 times of the second harmonic of 532, and about 75% of 1064, the overtone from the laser. It has shown up with no sample, and different samples in glass and plastic and quartz cuvettes, so we think it might have something to do with the laser. Does anyone have an explanation for this?

I am trying to model the combined effect of a static and dynamic load on a cantilever beam. I have calculated the dynamic response as follows

1) Natural frequency and mode shape extraction (modes 1-5), see image

2) Steady-state modal analysis gives the steady-state response across a range of frequencies. I am looking for deflection with direct model damping of 2%. If I am not mistaken, this form of analysis require a load independent of time and essential applies harmonic loading to each of the natural frequencies and calculates the response at each frequency.

I am unable to apply a static load at this stage (steady-state modal dynamics) to observe the combined effect. See image for the deflection as a function of frequency. This is precisely the plot I want if I was just considering dynamic response. But surely, this would change significantly with a static load.

I tried setting up a static load in a step prior to the frequency and steady-state modal dynamics step but that was of no use.

Any tips on how to do this.

FYI, I am actually trying to model a chassis experiencing cyclic and static loading from an engine and am using this to fully understand the problem.

I´ve read about a platform that is starting, which is called RONDA, and I would like to know if anyone has some experience with it: https://rondadna.wixsite.com/ronda/research

What are the power quality problems produced through a solar inverter other than harmonics, overvoltage, overcurrent, overfrequency, undervoltage, undercurrent, underfrequency and surge?

Hello

Anyone who has experience with operating a bidirectional DC-power supply as a load. I have an "ITECH6006C-500-40" and plan to operate a set-up with two motors as described in the simple sketch attached. I was primarily wondering if can directly just connect the 3-phase rectifier bridge (https://no.rs-online.com/web/p/bridge-rectifiers/0462130/) between the generator and the DC-supply(sink)? Are there any need to reduce the ripple output of the rectifier? I tried to simulate a simplified model in Simulink where I had the load represented by a resistor or a current source. See attached figure. The input current is alternating, though it does have harmonics.

best regard

Sveinung Attestog

Is it possible in practice to choose 10% (5th and 7th) harmonics injected to the grid for harmonic mitigation of grid current for a grid-tied PV system?

I generated files for minimization in Gromacs through Charmm-gui. But, when I was searching the bonds between Mg and amino acid in the section [bond], there were not. On the other hand, I could find possible interactions in the section [pairtype].

I would like to know if I could change the function from 1 to 6 in the section [pairtype] for harmonic restraints, because this change would not be possible according to the manual.

I attached my topology file

Hello,

I'm looking for examples in the human body which show periodicity, more precisely, I'm looking for examples of oscillating reactions that occur in the human body which can be modelled using the Hamiltonian of the harmonic oscillator such as described here:

for example, as mentioned in the comments, the circadian rhythm is controlled by the oscillation of protein concentration.

I want to read more about it, and I will be grateful to hear more examples so I can look for information about it online or if anyone could refer me to some reading material regarding this subject.

Thank you very much for your time and attention.

Relation between electrostatic based problem and time harmonic electrodynamics problem.

What is the reason of higher order harmonics in grid-connected converters and How these harmonics are eliminated?

One of the first things we learned about PDEs, is how the cylindrical harmonics (e.g. the Bessel functions J, I, K, and Y ) can be used to solve cylindrical boundary conditions. However I have never seen a paper discussing elliptical boundary conditions.

1) Is there another function that can be used for elliptical boundary conditions (NOT an ellipsoid but a prism with an elliptical cross-section) ?

2) What is the relation of these elliptical harmonics to the cylindrical harmonics?

3) If the answer to the above is yes, how might I compute these efficiently in MATLAB?

4) Is there a corresponding analog to Graf's addition theorem within the open literature?

Best Regards and Thanks!

my project is power quality and harmonic analysis ubder balancee load conditions under 0-2 Khz.

i was asked to measure each harmonic up to 2 kHz at different power levels and THD. i made a multidrive system upto 20 drives using Dipde rectifier and nonlinear loads

Change the grid impedance (1%, 5% and 15% base impedance) and see the differences.

so what frequency should i take my source and grid impedance values?

What does upto 2khz mean??

Do i keep my source at 2 khz ?

I read a review paper on СOVID. See the file. There is nothing about the

role of water in the process of infection and treatment from СOVID. How does a virus receive information from a cell that it can be attacked? How orders are transmitted in a cell about the beginning and end of complex processes of synthesis of biological molecules. Meanwhile, the role of water as a matrix of these processes is very great. Using the simplest models of the hydrophobic process, we have shown that in the water of the body, which is responsible for the hydrophobic interaction, there should be a large contribution of the water zero point energy (ZPE). A simple ZPE model is a harmonic oscillator whose energy is quantized. ZPE is a quantum phenomenon. The presence of ZPE in the body can be easily checked by the isotope effect. If there is a ZPE contribution in the cell water, then there must be an isotope effect.

To do this, you need to do the following experiment. To a certain concentration, humans and mice tolerate D2O well. It is necessary to select this concentration and compare the infection with COVID without the addition of D2O and with H2O.

I have not found any such research. If someone has such opportunities, I will consult in detail.

Hi Everyone,

Could anyone please help me find a good reference book in which I can find detailed information (including the basic formulas) about working of 3-phase inverters, harmonics, as well as their control techniques SPWM and SVM.

Thankyou in advance.

Kind regards,

Silpa

The OTA (Single Ended) is an amplifier consisting of a current mirror, controlled sources and a differential pair. It is advised to study / implement the different structures separately before making the complete design of the OTA. Explain the type of structure you choose for your design (topology)

This OTA must have:

to. Gain in tension> 70 dB

b. Gain band width> 100 dBMHz

c. CMRR> 110 dB

Emphasize in the specifications:

- Slew Rate

- Gain

- Power dissipation

- Common Mode rejection rate (CMRR)

- Power Supply Rejection ratio (PSRR)

- Band pass

- Total harmonic distortion

- Distortion of the 3rd harmonic

- The transconductance

- The power of supply

- Polarization current

- Offset

Thanks a lot