Resultados de
I have a pressure vs. time plot resulting from the input of an elastic wave, which I obtained from an Abaqus simulation. So, I have access to all the data. Now, I want to convert this time-domain graph into a frequency-domain graph using FFT in MATLAB.
I came across a code through ChatGPT, but I’m not fully confident in relying on it. Could anyone kindly clarify whether the formulas used for FFT in MATLAB are universal for all types of signals? Or is there a more effective and reliable method I should consider for this purpose?
Hi guys!
Im doing a project where i need to simulate a ship connected to the grid. I have a grid->converter AC-DC-AC -> dynamic load. My converter has to keep the voltage consistent and what changes is the current. Can somebody help me?
I've long used the Tensor Toolbox from Sandia in order to use tensors in Matlab, but recently found myself wanting to apply it on symbolic arguments, which don't appear supported. Some google-fu'ing resulted in (non-free) Tensorlab and some file-exchange entries of mixed quality. And of course, there's the recent tensorprod, which a) doesn't support symbolics and b) arguments aren't strictly tensors (rather "representations of tensors in a matrix type").
This all got me to thinking that it would be mighty nice to have general / native / comprehensive support for a tensor class in official Matlab - even if it were in a separate toolbox.
I am pleased to announce the 6th Edition of my book MATLAB Recipes for Earth Sciences with Springer Nature
also in the MathWorks Book Program
It is now almost exactly 20 years since I signed the contract with Springer for the first edition of the book. Since then, the book has grown from 237 to 576 pages, with many new chapters added. I would like to thank my colleagues Norbert Marwan and Robin Gebbers, who have each contributed two sections to Chapters 5, 7 and 9.
And of course, my thanks go to the excellent team at the MathWorks Book Program and the numerous other MathWorks experts who have helped and advised me during the last 30+ years working with MATLAB. And of course, thank you Springer for 20 years of support.
This book introduces methods of data analysis in the earth sciences using MATLAB, such as basic statistics for univariate, bivariate, and multivariate data sets, time series analysis, signal processing, spatial and directional data analysis, and image analysis.
Martin H. Trauth
Hello ThingSpeak Community,
I have an energy meter sending data of energy consumed in 4 rooms in hexadecimal values to Sigfox and I was trying to decode the payload and route it to ThingSpeak.
All the datas are sent at the same time.
But ThingSpeak only receives 1 of them and plots them.
However, the rest 3 are missing. Is this because I am trying the free version ?
Would the payed version be capable of receiving all the 4 messages ?
Imagine you are developing a new toolbox for MATLAB. You have a folder full of a few .m files defining a bunch of functions and you are thinking 'This would be useful for others, I'm going to make it available to the world'
What process would you go through? What's the first thing you'd do?
I have my own opinions but don't want to pollute the start of the conversation :)
I am glad to inform and share with you all my new text book titled "Inverters and AC Drives
Control, Modeling, and Simulation Using Simulink", Springer, 2024. This text book has nine chapters and three appendices. A separate "Instructor Manual" is rpovided with solutions to selected model projects. The salent features of this book are given below:
- Provides Simulink models for various PWM techniques used for inverters
- Presents vector and direct torque control of inverter-fed AC drives and fuzzy logic control of converter-fed AC drives
- Includes examples, case studies, source codes of models, and model projects from all the chapters
The Springer link for this text book is given below:
This book is also in the Mathworks book program:
It is time to support the cameraIntrinsics function to accept a 3-by-3 intrinsic matrix K as an input parameter for constructing the object. Currently, the built-in cameraIntrinsics function can only be constructed by explicitly specifying focalLength, principalPoint, and imageSize. This approach has drawbacks, as it is not very intuitive. In most application scenarios, using the intrinsic matrix
K=[fx,0,cx;
0,fy,cy;
0,0,1]
is much more straightforward and effective!
intrinsics = cameraIntrinsics(K)
Los invito a conocer el libro "Sistemas dinámicos en contexto: Modelación matemática, simulación, estimación y control con MATLAB", el cual ya está disponible en formato digital.
El libro integra diversos temas de los sistemas dinámicos desde un punto de vista práctico utilizando programas de MATLAB y simulaciones en Simulink y utilizando métodos numéricos (ver enlace). Existe mucho material en el blog del libro con posibilidades para comentarios, propuestas y correcciones. Resalto los casos de estudio
Creo que el libro les puede dar un buen panorama del área con la posibilidad de experimentar de manera interactiva con todo el material de MATLAB disponible en formato Live Script. Lo mejor es que se pueden formular preguntas en el blog y hacer propuestas al autor de ejercicios resueltos.
Son bienvenidos los comentarios, sugerencias y correcciones al texto.
MATLAB FEX(MATLAB File Exchange) should support Markdown syntax for writing. In recent years, many open-source community documentation platforms, such as GitHub, have generally supported Markdown. MATLAB is also gradually improving its support for Markdown syntax. However, when directly uploading files to the MATLAB FEX community and preparing to write an overview, the outdated document format buttons are still present. Even when directly uploading a Markdown document, it cannot be rendered. We hope the community can support Markdown syntax!
BTW，I know that open-source Markdown writing on GitHub and linking to MATLAB FEX is feasible, but this is a workaround. It would be even better if direct native support were available.
I noticed recently that my data is no longer updating on thingspeak again. Is there a connectivity issues with thingspeak
my code is as below:
#include "DHT.h"
#define DHTPIN 15 // what pin we're connected to
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);
#define THINGSPEAK_API_KEY "1P4RY69D3YMP9R5W"
#include <SoftwareSerial.h>
#include <OneWire.h>
#include <DallasTemperature.h>
//-----------------------------
#include <ArduinoJson.h>
StaticJsonDocument<200>JsonDocument;
SoftwareSerialmyserial(10, 11);
//-------------------------
float voltage;
unsignedintfrac;
//---------------------
#define ONE_WIRE_BUS 5
OneWireoneWire(ONE_WIRE_BUS);
DallasTemperaturesensors(&oneWire);
floatCelcius = 0;
float Fahrenheit = 0;
//==========================================================================================================
bytesensorInterrupt = 0; // 0 = digital pin 2
bytesensorPin = 2;
// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
floatcalibrationFactor = 5.5; //==========================================================we change cal factor 4.5 to 5.5 if not work chnage again(4.5)
//========== 5.5 calibration factor is working efficent then 4.5 , 7.5 ,and 6.5
volatile byte pulseCount;
floatflowRate;
unsignedintflowMilliLitres;
unsigned long totalMilliLitres, tempTotal = -1;
unsigned long oldTime;
//-------------------------------------------------------
intpH_Value;
float Voltage;
//----------------------------------------------------------------------------------------------
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
myserial.begin(9600);
//--------------------------------
pinMode(sensorPin, INPUT);
digitalWrite(sensorPin, HIGH);
pulseCount = 0;
flowRate = 0.0;
flowMilliLitres = 0;
totalMilliLitres = 0; // ============================================================
oldTime = 0;
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
sensors.begin();
//------------------------------------------------
/********************GSM Communication Starts********************/
if (myserial.available())
Serial.write(myserial.read());
myserial.println("AT");
delay(1000);
myserial.println("AT+SAPBR=3,1,\"Contype\",\"GPRS\"");
delay(1000);
ShowSerialData();
myserial.println("AT+SAPBR=3,1,\"APN\",\"www\"");//APN
delay(1000);
ShowSerialData();
myserial.println("AT+SAPBR=1,1");
delay(1000);
ShowSerialData();
myserial.println("AT+SAPBR=2,1");
delay(1000);
ShowSerialData();
//---------------------------------
}
void loop() {
// put your main code here, to run repeatedly:
inti;
for (i = 0; i< 20; i++)
{
flow_meter();
}
temperature();
turbidity();
delay(1000);
gsm();
}
voidflow_meter()
{
if ((millis() - oldTime) > 1000) // Only process counters once per second
{
// Disable the interrupt while calculating flow rate and sending the value to
// the host
detachInterrupt(sensorInterrupt);
// Because this loop may not complete in exactly 1 second intervals we calculate
// the number of milliseconds that have passed since the last execution and use
// that to scale the output. We also apply the calibrationFactor to scale the output
// based on the number of pulses per second per units of measure (litres/minute in
// this case) coming from the sensor.
flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;
// Note the time this processing pass was executed. Note that because we've
// disabled interrupts the millis() function won't actually be incrementing right
// at this point, but it will still return the value it was set to just before
// interrupts went away.
oldTime = millis();
// Divide the flow rate in litres/minute by 60 to determine how many litres have
// passed through the sensor in this 1 second interval, then multiply by 1000 to
// convert to millilitres.
flowMilliLitres = (flowRate / 60) * 1000;
// Add the millilitres passed in this second to the cumulative total
totalMilliLitres += flowMilliLitres;
// Print the flow rate for this second in litres / minute
/* Serial.print("Flow rate: ");
Serial.print(int(flowRate)); // Print the integer part of the variable
Serial.print("."); // Print the decimal point */
// Determine the fractional part. The 10 multiplier gives us 1 decimal place.
frac = (flowRate - int(flowRate)) * 10;
Serial.print(frac, DEC) ; // Print the fractional part of the variable
Serial.println("L/min");
/* // Print the number of litres flowed in this second
Serial.print(" Current Liquid Flowing: "); // Output separator
Serial.print(flowMilliLitres);
Serial.print("mL/Sec");
// Print the cumulative total of litres flowed since starting
Serial.print(" Output Liquid Quantity: "); // Output separator
Serial.print(totalMilliLitres);
Serial.println("mL"); */
if ( tempTotal != totalMilliLitres ) {
tempTotal = totalMilliLitres;
// displayVolumeOfWater(totalMilliLitres );
}
// Reset the pulse counter so we can start incrementing again
pulseCount = 0;
// Enable the interrupt again now that we've finished sending output
attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
}
//=========================================================================================================================
}
voidpulseCounter()
{
// Increment the pulse counter
pulseCount++;
}
//-------------------------------------------------------------------------
void temperature()
{
sensors.requestTemperatures();
Celcius = sensors.getTempCByIndex(0);
Fahrenheit = sensors.toFahrenheit(Celcius);
Serial.print(" C ");
Serial.print(Celcius);
// Serial.print(" F ");
// Serial.println(Fahrenheit);
delay(1000);
}
//------------------------------------------------------------
void turbidity()
{
intsensorValue = analogRead(A0);
voltage = sensorValue * (5.0 / 1024.0);
// Serial.println ("Sensor Output (V):");
Serial.println (voltage);
// Serial.println();
delay(1000);
}
//------------------------------------------------------------
voidgsm()
{
myserial.println("AT+HTTPINIT");
delay(1000);
ShowSerialData();
myserial.println("AT+HTTPPARA=\"CID\",1");
delay(1000);
ShowSerialData();
StaticJsonDocument<200>JsonDocument;
JsonObject& object = JsonDocument.createObject();
object.set("TE", Celcius);
object.set("TU", voltage);
object.set("WF", frac);
delay(1000);
object.printTo(Serial);
Serial.println(" ");
String sendtoserver;
object.prettyPrintTo(sendtoserver);
delay(1000);
//myserial.println("AT+HTTPPARA=\"URL\",\"https://api.thingspeak.com/update?api_key=\""); //Server address
myserial.println("AT+HTTPPARA=\"URL\",\"https://api.thingspeak.com/update?api_key=\""); //Server address
delay(1000);
ShowSerialData();
myserial.println("AT+HTTPPARA=\"CONTENT\",\"application/json\"");
delay(1000);
ShowSerialData();
myserial.println("AT+HTTPDATA=" + String(sendtoserver.length()) + ",100000");
Serial.println(sendtoserver);
delay(1000);
ShowSerialData();
myserial.println(sendtoserver);
delay(2000);
ShowSerialData;
myserial.println("AT+HTTPACTION=1");
delay(1000);
ShowSerialData();
myserial.println("AT+HTTPREAD");
delay(1000);
ShowSerialData();
myserial.println("AT+HTTPTERM");
delay(1000);
ShowSerialData;
}
voidShowSerialData()
{
while (myserial.available() != 0)
Serial.write(myserial.read());
delay(1000);
}
I am very pleased to share my book, with coauthors Professor Richard Davis and Associate Professor Sam Toan, titled "Chemical Engineering Analysis and Optimization Using MATLAB" published by Wiley: https://www.wiley.com/en-us/Chemical+Engineering+Analysis+and+Optimization+Using+MATLAB-p-9781394205363
Also in The MathWorks Book Program:
Chemical Engineering Analysis and Optimization Using MATLAB® introduces cutting-edge, highly in-demand skills in computer-aided design and optimization. With a focus on chemical engineering analysis, the book uses the MATLAB platform to develop reader skills in programming, modeling, and more. It provides an overview of some of the most essential tools in modern engineering design.
Chemical Engineering Analysis and Optimization Using MATLAB® readers will also find:
- Case studies for developing specific skills in MATLAB and beyond
- Examples of code both within the text and on a companion website
- End-of-chapter problems with an accompanying solutions manual for instructors
This textbook is ideal for advanced undergraduate and graduate students in chemical engineering and related disciplines, as well as professionals with backgrounds in engineering design.
Need code to collect data of waterflow sensor using ESP 8266 and to stoe it in ThingSpeak cloud
Ciao a Tutti,qualche mese fa avevo costruito una stazione meteo con un esp32 e vari sensori.
Tutto funzionava, adesso però ho riprovato, e non funziona più. Ho provato a creare un canale nuovo con nuovo ID canale, nuovo ID Client, nuovo Utente (uguale al Client) e nuova Password. si connette (ho inserito un comando se connesso a MQTT scrivi.....) ma non publica i dati.
Non reisco a saltarne fuori, ècambiato qualche cosa?
grazie a tutti
Too small
22%
Just right
38%
Too large
40%
2648 votos
Hello,
could it be that there is currently is a stability problem with the MQTT-Broker? I can establisth a connection successfully using the MQTTX client (web and win64 installation). I tried all possible ports an connection types. It disconnects all the time after a few seconds of establishing a connection successfully. So it was not possible to subscribe any item. I do not think the problem is in my side... By the way, protocol verision 3.1.1 ist supported, 5.0 not, am I right?
Maybe you could give me a hint,
Best regards,
Manfred
In one of my MATLAB projects, I want to add a button to an existing axes toolbar. The function for doing this is axtoolbarbtn:
axtoolbarbtn(tb,style,Name=Value)
However, I have found that the existing interfaces and behavior make it quite awkward to accomplish this task.
Here are my observations.
Adding a Button to the Default Axes Toolbar Is Unsupported
plot(1:10)
ax = gca;
tb = ax.Toolbar
Calling axtoolbarbtn on ax results in an error:
>> axtoolbarbtn(tb,"state")
Error using axtoolbarbtn (line 77)
Modifying the default axes toolbar is not supported.
Default Axes Toolbar Can't Be Distinguished from an Empty Toolbar
The Children property of the default axes toolbar is empty. Thus, it appears programmatically to have no buttons, just like an empty toolbar created by axtoolbar.
cla
plot(1:10)
ax = gca;
tb = ax.Toolbar;
tb.Children
ans = 0x0 empty GraphicsPlaceholder array.
tb2 = axtoolbar(ax);
tb2.Children
ans = 0x0 empty GraphicsPlaceholder array.
A Workaround
An empty axes toolbar seems to have no use except to initalize a toolbar before immediately adding buttons to it. Therefore, it seems reasonable to assume that an axes toolbar that appears to be empty is really the default toolbar. While we can't add buttons to the default axes toolbar, we can create a new toolbar that has all the same buttons as the default one, using axtoolbar("default"). And then we can add buttons to the new toolbar.
That observation leads to this workaround:
tb = ax.Toolbar;
if isempty(tb.Children)
% Assume tb is the default axes toolbar. Recreate
% it with the default buttons so that we can add a new
% button.
tb = axtoolbar(ax,"default");
end
btn = axtoolbarbtn(tb);
% Then set up the button as desired (icon, callback,
% etc.) by setting its properties.
As workarounds go, it's not horrible. It just seems a shame to have to delete and then recreate a toolbar just to be able to add a button to it.
The worst part about the workaround is that it is so not obvious. It took me a long time of experimentation to figure it out, including briefly giving it up as seemingly impossible.
The documentation for axtoolbarbtn avoids the issue. The most obvious example to write for axtoolbarbtn would be the first thing every user of it will try: add a toolbar button to the toolbar that gets created automatically in every call to plot. The doc page doesn't include that example, of course, because it wouldn't work.
My Request
I like the axes toolbar concept and the axes interactivity that it promotes, and I think the programming interface design is mostly effective. My request to MathWorks is to modify this interface to smooth out the behavior discontinuity of the default axes toolbar, with an eye towards satisfying (and documenting) the general use case that I've described here.
One possible function design solution is to make the default axes toolbar look and behave like the toolbar created by axtoolbar("default"), so that it has Children and so it is modifiable.
I am curious as to how my goal can be accomplished in Matlab.
The present APP called "Matching Network Designer" works quite well, but it is limited to a single section of a "PI", a "TEE", or an "L" topology circuit.
This limits the bandwidth capability of the APP when the intended use is to create an amplifier design intended for wider bandwidth projects.
I am requesting that a "Broadband Matching Network Designer" APP be developed by you, the MathWorks support team.
One suggestion from me is to be able to cascade a second section (or "pole") to the first.
Then the resulting topology would be capable of achieving that wider bandwidth of the microwave amplifier project where it would be later used with the transistor output and input matching networks.
Instead of limiting the APP to a single frequency, the entire s parameter file would be used as an input.
The APP would convert the polar s parameters to rectangular scaler complex impedances that you already use.
At that point, having started out with the first initial center frequency, the other frequencies both greater than and less than the center would come into use by an optimization of the circuit elements.
I'm hoping that you will be able to take on this project.
I can include an attachment of such a Matching Network Designer APP that you presently have if you like.
That network is centered at 10 GHz.
Kimberly Renee Alvarez.
310-367-5768
