Systems Definition and 1000 Threads

A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expressed in its functioning. Systems are the subjects of study of systems theory.

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  1. J

    What does ZPB mean in power systems?

    Hi, So my power system book has a diagram for zero sequence impedance. I cannot find the full form of ZPB. I googled it up but couldn't come across anything.
  2. BiGyElLoWhAt

    I How to fill the stress energy tensor for multi body systems

    Say I wanted to set up EFE for the Earth and moon. How do I actually go about filling the stress energy tensor? I'm referencing the wikipedia page. So the time-time should be approximately E/c^2V, so for the Earth moon system ##T_{00} = \frac{3}{4\pi r_E^3}\frac{1}{c^2}(M_Ec^2 + 2/5...
  3. maajdl

    Surprise? Entropy changes for systems in a canonical state

    Every year since the 90's I come back to some of my pet topics in physics, like statistical physics. This time it was the reading of a Wikipedia article on entropy that surprised me. The derivation of the second law from the Gibbs entropy was unknown to me. I didn't know how heat, how change of...
  4. S

    A Does a wavefunction in a cartesian system create a one-dimensional subspace?

    Hi, I have heard (or imagined) that a wavefunction, where Psi is on the y-axis and the positions x is naturally on the x-axis, is really a one-dimensional system in Physics (not in mathematics), because the signal or the oscillation of the wavefunction is not really a dimension, and only the...
  5. Joppy

    MHB Discrete dynamical systems - Invertible maps

    Hi (Sleepy), I suspect this is trivial, but I couldn't find any info onlin. Consider the folowing map: $\phi_{n+1} = f(\phi_n ; \Theta, a) = (\phi_n + \Theta + a \sin \phi_n) \mod 2\pi$. I need to check if is invertible: $\phi_n = f^{-1} (\phi_{n+1}; \Theta, a)$ when a = 1/2 or 3/2...
  6. T

    Understanding Expansion Fans and Reflected Waves in Propulsion Systems

    "For simplicity, let us assume the flow turns around a corner downstream of the throat, where the Mach number is M0 > 1, to an angle θ1, and let us indicate just three of an infinite number of waves making up the "expansion fan". Since the centerline is an axis of symmetry, the waves must...
  7. D

    Solving Systems of Linear Equations in Two Variables- Graphs

    Homework Statement Solve the system of equations: { (1/2)x-y=3 and x=6+2y Homework Equations NA The Attempt at a Solution The solution is 3=3, which is an identity, which means that there is an infinite amount of solutions to the system. Here's where my question lies (asked my teacher but...
  8. JTC

    I Coordinate systems vs. Euclidean space

    Good Morning I am having some trouble categorizing a few concepts (I made the one that is critical to this post to be BOLD) Remote parallelism: the ability to move coordinate systems and frames around in space. Euclidean Space Coordinate systems: Cartesian vs. cylindrical I am aware that if...
  9. pairofstrings

    Software for embedded systems in OOPs

    Hello. If Linux is completely written in C(?) then I need a strong reason to opt for OOPs for Embedded Systems software. Can anybody tell me a situation or a circumstance that would make me use Object Oriented Programming principles to write software for Embedded Systems? Thanks.
  10. T

    I Evaluating the integral in spherical coordinates - how to do it correctly?

    I should evaluate ##\int d^3 p \ \exp(i \vec{p} \cdot \vec{x}) / \sqrt{|p| + m^2}## over all ##\mathbb{R}^3##. How can I do this in spherical coordinates? Since ##\vec{p}## is a position vector in ##\mathbb{R}^3##, our ##\vec{r}## of the spherical coordinates would be just equal to ##\vec{p}##...
  11. R

    Newton's first law of motion and Inertial Systems

    I have just begun my journey in Classical Mechanics with the book "An Introduction to Mechanics" by Kleppner and Kolenkow. I find myself stuck at Newton's first law. The book presents Newton's first law as follows: "Newton's first law is an assertion that inertial frames exist." The book also...
  12. D

    MHB Interested in Graduate Modeling Lecture Notes on Dynamical Systems?

    I am in the process of writing a lecture out for my Graduate modeling class I teach. I normally don't write lectures out in LaTex or use PDF's because I write on the dry erase board, but if anyone is interested I wouldn't mind spending the time to type out some notes on the topic. The topic...
  13. D

    MHB Sensitivity Analysis model for omnivory systems (coupled system of ode's)

    \chapter{Stage Structured Omnivory Model} %\indent For our initial computations we will be using a standard Lotka-Volterra omnivory model which was developed to analyze the population and community level dynamics. The model depicted below (figure 1.4) is a standard Lotka-Volterra model of...
  14. D

    MATLAB Coupled systems of ODE's solved by matlabs ODE45 (Runge Kutta Alg.)

    Use the code as needed, its free to all! Please note this code is only for one mfile, you will need to add them all to the same file path for it to work. Others will be in the next post. They have to run simultaneously to work and give output. function dydt =...
  15. D

    MHB How Can We Convert Higher Order Differential Equations into First Order Systems?

    First, some may ask why would do we care that we can convert a 3rd order or higher ODE into a system of equations? Well there are quite a few reasons. 1- Almost all first order systems are easier to solve numerically using computer systems (matlab, maple, etc). Yes, it takes some working out...
  16. PhotonSSBM

    Probabilities for two spin systems interacting in isolation

    Homework Statement Consider a system A consisting of a spin 1/2 having magnetic moment ##\mu_0##, and another system A' consisting of 3 spins 1/2 each having magnetic moment ##\mu_0##. Both systems are located in the same magnetic field B . The systems are placed in contact with each other so...
  17. F

    I How do you solve systems of equations in complex physics problems?

    It seems like systems of equation are part of almost every complex physics problem. What exactly are the rules or steps for solving such equations? I know how to solve a basic linear system of equations with two variables, but how do solve more complicated systems like non-linear systems of...
  18. CMW328i

    Noise Modelling - Digital communication systems

    Hi all, Teacher here looking for some guidance. I'm teaching a class that I took myself a few years back, and I'm looking at my solution to a problem but I have a random value in my answer (which I know to be correct) but I can't for the life of me remember where this value came from! Can anyone...
  19. Kirk Truax

    PWR Refueling Systems and Procedures

    Hey all, I was wondering if anyone can help me out with understanding the PWR refueling process? I'm an undergrad getting introduced to these systems and was hoping there was someone in the industry that might have some insight into the details of this. In regard to the removal of the old...
  20. S

    I Nearly Lorentz Coordinate Systems: Is h a Tensor?

    Hello! I am reading Schutz A first course in GR and he introduces the Nearly Lorentz coordinate systems as ones having a metric such that ##g_{\alpha\beta} = \eta_{\alpha\beta} + h_{\alpha\beta}##, with h a small deviation from the normal Minkowski metric. Then he introduces the Background...
  21. B

    I Notation for systems of simultaneous equations

    What notation would I need to use in order to write a mathematical statement to define a System S of simultaneous equations - let's say ax+by=c and ex+fy=g.
  22. F

    A Numerical solution of Hamiltonian systems

    The question is very general and could belong to another topic, but here it is. Suppose one wants to solve the set of differential equations $$ \frac{\partial x}{\partial t}=\frac{\partial H(x,p)}{\partial p},$$ $$\frac{\partial p}{\partial t}=-\frac{\partial H(x,p)}{\partial x},$$ with some...
  23. R

    Dynamic pressure variances in sealed and pressurised systems

    Hi Last did physics about 50 years ago but have become interested in how pressuried fluids behave in sealed containers when they are rapidly agitted or otherwise brought into motion. Envisage a large circular container with a central power driven agitator. Two cylinders are attached . The whole...
  24. Sunny Singh

    I Chaos vs purely exponentially growing systems

    I have just started reading chaos from the MIT OpenCourseWare and the following passage has confused me. "The sensitivity to initial conditions is important to chaos but does not itself differentiate from simple exponential growth, so the aperiodic behavior is also important. In the definition...
  25. Spinnor

    Squash-like plant, vines form secondary root systems?

    We have some type of squash plant growing in a small garden. It remarkable how much it has spread. I would think it advantageous for such a plant to form additional root systems, try as I might I do not see them on this plant. Is that typical of squash and pumpkin type plants, no additional root...
  26. C

    I Hamiltonian as total energy for natural systems?

    Could someone please prove that the H=T+V for systems where the transformation from Cartesian to Generalized coordinates is time independent. I have read through the proofs in Taylor's classical mechanics and Goldstein's but do not understand them.
  27. J

    Insulation monitoring in some marine isolated electrical systems

    Hi, In some marine isolated electrical systems I saw that only one phase insulation resistace is monitored. Why? If something happens on other phases I will have no information about that or...? Regards!
  28. B

    A Hahn-Banach From Systems of Linear Equations

    In this paper on the history of functional analysis, the author mentions the following example of an infinite system of linear equations in an infinite number of variables ##c_i = A_{ij} x_j##: \begin{align*} \begin{array}{ccccccccc} 1 & = & x_1 & + & x_2 & + & x_3 & + & \dots \\ 1 & = & &...
  29. K

    I Preamplifiers in radiation measurement systems

    In the radiation detection, it's of common use pulse-type systems, which have a preamplifier between the detector and the amplifier. I have read that the preamplifier primary function is reduction of attenuation of the signal that exits from the detector by matching the impedance of the detector...
  30. jdawg

    Stable, Neutrally Stable, and Unstable Systems

    Homework Statement I'm having difficulty knowing how to determine if a given differential equation represents a stable, neutrally stable, or an unstable system. I was given a hint to focus on the homogeneous solution, so is the particular solution not important for determining if the...
  31. kostoglotov

    Viscous drag parallel to the axis of rotation: Control Systems

    Homework Statement https://i.imgur.com/WPAKuf4.png seeking G(s) = \frac{\theta_2(s)}{\tau(s)} Homework EquationsThe Attempt at a Solution What does it mean when the viscous drag is parallel to the axis of rotation?[/B] It also turns out that this system needs two equations. I can sort...
  32. Drakkith

    Solution Sets of Linear Systems

    Homework Statement Q. Let A be an m by n matrix. Assume that the equation Ax=b is consistent for some b≠0 in Rn. Moreover, assume that Ax=b has a unique solution. Does the equation Ax=0 have a non-trivial solution? Is it possible to find a vector V in Rm so that the system Ax=V has infinitely...
  33. S

    A [itex]L^2(-\infty, +\infty)[/itex] and LTI systems

    Hi everyone, I'm an electrical engineer trying to make a little bit of order in my mind about eigenfunction theory, sturm liouville operators (regular and singular) on my own free time and I thought I was grasping almost everything, but I had a little doubt that is actually coming from the field...
  34. Evanish

    Question about missile defense systems and lasers

    I was reading a news article about powerful lasers being used in missile defense systems, and I was wondering if multiple weak laser can work together to do the same job as one strong laser. For example can a thousand 1 Kw lasers in different locations be made to point at a single point on a...
  35. K

    How to determine efficiencies of electric heating systems?

    I am building a house and would like to understand how to perform an energy balance/efficiency calculation on various electrical heating systems
  36. W

    General Question on 32- and 64- bit systems

    Hi All, Just curious on pros/cons of installing software designed for 32- bit systems in a 64-bit machine (Windows 8.1*)? * I have never been able to tell the difference, if any, between Win 8 and Win 8.1 .
  37. Mind----Blown

    I Miller indices for hexagonal crystal systems

    Hi everyone, to find the draw the direction for a given miller index say, [1234] we first convert this miller index consisting of 4 indices into one containing 3 indices. To do so, we have a set of formulae prescribed in almost every book. Sadly I haven't been able to come across a single book...
  38. B

    Why are TN-C systems not allowed for computer equipment?

    Hi Why are TN-C systems not allowed for computer equipment and similar devices? After some reading they mention it is because of circulation of harmonic currents in the PEN condcutor, but I am not able to understand what circular path they circulate in?
  39. D

    Entropy of ensemble of two level systems

    Homework Statement The fundamental equation of a system of \tidle{N} atoms each of which can exist an atomic state with energy e_u or in atomic state e_d (and in no other state) is F= - \tilde{N} k_B T \log ( e^{-\beta e_u} + e^{-\beta e_d} ) Here k_B is Boltzmann's constant \beta = 1/k_BT...
  40. V

    Engineering Is passion the key to success in power engineering?

    So I am 21 years old, I only recently found out that I am interested in electrical engineering. I live in NYC and am heading into cuny city tech for my first semester. E.E is a very broad field and I think that going into power engineering would be a good career move because it cannot be...
  41. K

    Can yaw motion still occur in a quadcopter in vacuum?

    So I recently developed an interest in quad-rotors and was getting stated with its dynamics. I am particularly intrigued by the yaw motion of a quad-copter which comes into effect as a result of torques of the motors. When the motor torques are variable, we observe the yaw motion as result of a...
  42. T

    Can hydraulic systems replace ebikes in power assisted cycle

    Instead of an electric motor, can it be substituted with an hydraulic force / power amplifying system instead? If yes, how would it work? Could chains still be used? Instead of an electric motor powering the hydraulic system, could the rider power the hydraulic system through force / power...
  43. P

    Piezoelectric energy harvesting systems

    Hello, I am an student of Engineering and I come a cross of a doubt that I would like to investigate a bit more. I would like some information or some directions to the right path for the following. I would like to know how could I calculate the harvesting energy of an area for a piezoelectric...
  44. Pushoam

    I Laws of physics and inertial systems

    It is not the laws of physics, but the forms of laws of physics which are the same in all inertial frames. Comment."The forms of laws of physics are the same in all inertial frames" is a necessary condition (put by scientists ) to get satisfied by something which has to be called as a law of...
  45. R

    B Air movement in an exhaust systems

    Hello I'm trying to understand how exhaust systems work .In general I want to understand how air movement changes according to leight of vent tubes. Example I have made little vent system with in lane fan that sucks air out of room. As I understand air speed in tube that is pulling air from...
  46. R

    Determine the load voltage levels in feeder systems

    Homework Statement Hi guys, I was just wondering if anybody could help me with the below question Homework EquationsThe Attempt at a Solution Radial Total load = 3.2 /_-36.87deg + 2.3 /_ 53.13deg =(2.56 - j1.92) +(1.38 +j1.84) = (3.94 -j0.08)...
  47. Math Amateur

    Foundations Construction of the Number Systems ... Natural, Integers, etc

    At present I am trying to understand the construction of the number systems ... natural, integers, rationals and reals ... What do members of PFs think is the clearest, most detailed, most rigorous and best treatment of number systems in a textbook or in online notes ... ? NOTE: I am currently...
  48. Math Amateur

    MHB Construction of the Number Systems .... Natural, Integers, Rationals and Reals

    At present I am trying to understand the construction of the number systems ... natural, integers, rationals and reals ... What do members of MHBs think is the clearest, most detailed, most rigorous and best treatment of number systems in a textbook or in online notes ... ? NOTE: I am...
  49. Ackbach

    MHB Data Science and Systems Integration Blog Post

    Really excited about this blog post by yours truly. Wineman Technology is going places!
  50. bachir1994

    Neutral current in three-phase systems

    Hello, In three-phase systems, star coupling for example, and in the case where single-phase sources are supplied using the three phases L1, L2 and L3 with a common neutral return, My first question is: when one is balanced il1 = il2 = Il3 is what the current flowing in the neutral is...
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