What is Systems: Definition and 1000 Discussions

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. W

    Understanding an Exercise on LTI Systems with Unit Sample Response

    Hello, am having an understanding problem, about an exercice on LTI systems with unit sample response. i've been given the graphical depicted output y[n], and the following output x[n]= u[n]-u[n-2] the system is as follow x[n]----> h1[n]----->h2[n]------>y[n] with h2[n]= s[n] - s[n-1]...
  2. L

    Linear Algebra Systems of Equations

    Homework Statement Consider the following two system of equations: y_{1}=-2x_{1}-x_{2}+2x_{3} y_{2}=2x_{1}+2x_{2}-3x_{3} y_{3}=-2x_{1}-2x_{2}+2x_{3} and z_{1}=3y_{1}-4y_{2}-3y_{3} z_{1}=3y_{1}-y_{2}-4y_{3} Rewrite these 2 systems as Ax=y and By=z. Use this to get C so that Cx=z...
  3. C

    Power loss in different drive systems?

    Firstly, I am not an engineer or engineering student. I come from an art/creative background. However, in what may be arrogance, I'm convinced I can solve a problem that no one but me thinks is a problem. Further, I'm spitting in the face of a system that has been fine for everyone else for...
  4. N

    Systems of Linear equation/matrices problem. Need some help.

    I have this math packet for homework and it has loads of problems on systems of equations and matrix. The last few problems have been bothering me. Here it is: To manufacture an automobile require painting, drying, and polishing. Epsilon Motor Company produces three types of cars: the Delta...
  5. L

    Do chaotic systems point to a direction of time?

    Hi first time poster. I have a question which has been intriguing me for some time. Are most chaotic systems also chaotic if played backwards in time? For example if we played a video of a double pendulum, will it exhibit the similar chaotic behaviour if played to someone in reverse? I guess the...
  6. N

    Help with Signals and Systems Differential Equation Problem

    Hey guys, I was wondering if I could receive any help on a homework problem I have. I need to find the differential equation relating the input to the output. I've began working on it but feel like I've hit a brick wall in my work, any input? Homework Statement Attachment - Problem...
  7. M

    Engineering Master's in Energy Systems Engineering

    Hello all, I was recently accepted to a program overseas that offers said degree. I think it sounds great, but I'm more than slightly worried about job prospects in the field. Can anyone offer advice?
  8. S

    Coordinate Systems Homework: Prove \nabla.\vec{r}=3

    Homework Statement For the cartesian, cylindrical, spherical coordinate system, prove that \nabla.\vec{r} = 3 and \nablax\vec{r}=0 Homework Equations For cylindrical coord system, \vec{r} = s\vec{s} + z\vec{z} \nabla = \vec{s} \delta/\deltas +...
  9. R

    State space representations in LTI systems

    I just started my first graduate level controls class this semester, and it looks like my professors notes aren't going to be quite enough. Can anybody recommend a good book with lots of state space representation examples, or if not a book, a website would do fine as well. Thanks for any help.
  10. I

    Properties of Systems: Memoryless, Causal, time invariant, linear

    Hi, I need a hand with my reasoning on the following question. I have answered all the questions, but not too sure weather they are correct. Please guide me or point me on the right direction if they are not correct. Regards 1. A system defined by the following equation y(t)=[x(t-2)]^2...
  11. L

    MATLAB Systems of equations in matlab

    hello everybody! T1=A T1'+B(T0'+T2'+T0+T2) T2=A T2'+B(T1'+T3'+T1+T3) T3=A T3'+B(T2'+T4'+T2+T4) if A,B,T0,T4 and everything in (') character is known, i have T1,T2,T3 to find and 3 equations. how do i use MATLAB to solve this?(i have a...
  12. M

    Linear algebra systems ,Ax=b,Ax=0

    Homework Statement Let be Ax=b any consistent system of linear equations, and let be x1 a fixed solution. Show that every solution to the system can be written in the form x=x1 +x0, where x0 is a solution Ax=0 . Show also that every matrix of this form is a solution Homework Equations...
  13. T

    Lorenz transformations for two parallel inertial systems

    Thanks for reading! Homework Statement I have been given a proof for the lorentz transformations (which I only partly understand) that relied on the two relativity postulates (equivalence of inertial systems and the speed of light being constant) for the case of two standard inertial...
  14. P

    Ionization Energy / Electron Affinity Systems

    Homework Statement We have two atomic systems, Na+ + Cl- (System A) and Na + Cl (System B), where all the particles are separated in the infinite distance. Which system (A or B) is higher in energy? Describe the energy difference of the two systems by ionization energy and the electron...
  15. S

    Understanding classical stochastic systems

    This is an extract from my lecture notes: "For classical stochastic systems, w(p,x,t)dpdx = prob. particle is in dpdx. w\geq0 \int dp \int dx w(p,x) = 1." 1. Can anyone please explain what a classical stochastic system is? 2. Why is there a question of probability in analysing such a...
  16. P

    Do entangled systems have parts?

    Some say that there are parts but their properties depend on the whole. But if we cannot assign properties to the 'parts' of an entangled system, what can it be to be a 'part' or any kind of entity in the first place? Can we say that there are parts but that they are not independent? What can...
  17. Rasalhague

    What is the meaning of the shorthand notation used in dynamical systems?

    I have some questions about what I think is a fairly standard and common short-hand notation used in physics. Today I watched lecture 2 in the nptelhrd series Classical Physics by Prof. V. Balakrishnan. In it, he models a kind of system called a simple harmonic oscillator, I think using TC =...
  18. B

    Understanding Electric Power Systems: Minus Signs in the Admittance Matrix

    [b]http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-061-introduction-to-electric-power-systems-spring-2007/assignments/ps1ans.pdf Problem #3 Where do the minus signs come from in the admittance matrix? also, there is this statement "Thus it is clear that R3 = 1/3...
  19. J

    Determine Periods of CT Signals

    Hi everyone I really don't know how to start this questions, please help me. Thank you in advance for all your help & support. Determine if each of the following CT signals is periodic. If periodic find it period. a) x(t)=2sin(10\pit-30degrees) b) x(t) = 2 cos (\sqrt2\pit) c)x(t) = 2...
  20. 1

    Online systems for serious services

    Has anyone ever noticed that the online portals for things like schools, colleges, and banks are flat out awful, while sites like newgrounds feature state of the art online portals?
  21. G

    EM field of cell, microtubules, quantum behavior in biological systems

    The cytoskeletal structures were considered responsible for the elementary cellular intelligence in the past. (For example, see the articles from Albrecht Buehler. http://www.basic.northwestern.edu/g-buehler/FRAME.HTM.) Microtubules are pipe-like structures made of two kinds of proteins...
  22. D

    Electrical grid tied PV systems

    [b]1. I have not seen IEEE 1547-2003 as this question pertains to it. They say that small PV systems are tied into the grid, if the wave sign of a PV inverter is a square wave how does that marry to the wave of electricity flowing on the existing grid? Does this current just get gobbled up so to...
  23. J

    Input output relations in signals and systems

    Homework Statement I have a trouble understanding what would be the output when for example we say let's input the signal x(k*n) or x(n-n0) to the system... this has given me problems when having to solve systems for which I have to check the property of time invariance suppose we have a...
  24. F

    Understanding Chassis Ground in Car Electrical Systems

    I was just wondering about chassis ground in the context of a cars electrical system. If the return path back to the battery is through the metal chassis of the car, then what stops you from receiving a shock when you touch the car chassis ? Thanks.
  25. jfy4

    States of Composite Systems, p. 216: Ballentine

    Hi everyone, I am working through Ballentine's Quantum Mechanics books, and I am stuck... I would be appreciative if someone could walk me through this section with some help. Here is my first confusion. In this case then |a_{m'}b_{n'}\rangle\langle a_{m'}b_{n'}| do not form a complete...
  26. A

    Nonlinear Orthonormal Bases for Dynamical Systems in 3D

    I propose 27 scalar functions {fn : n = 1,2,…,27}, 9 delay-coupled 3D unit vectors {eij : i,j = 1,2,3} of general periodic nature, 7 ortho-normal bases {Zk : k = 0,1,2,…,6} each having three 3D unit vectors, 4 tensors {Y3,Y4,Y5,Y6} of order 2 and a tensor E of order 3. Z3-Z6 and E are defined...
  27. strangerep

    Hartle: QM of Individual Systems (1968)

    In Fredrik's recent thread: https://www.physicsforums.com/showthread.php?t=506326 some questions arose about this paper: J. B. Hartle, "Quantum Mechanics of Individual Systems", Am. J. Phys., vol 36, no 8, (1968), pp704-712. [For other readers, you'll need to have read or be able to...
  28. S

    Why we need different number systems ?

    why there are so many number systems when we can only use anyone of them ? What's the need of octal and hexadecimal ?
  29. T

    System properties e.g. causality/memory (Signals and Systems)

    Homework Statement Determine if the system y(t) = sin(x(t)) is time invariant, linear, causal, and/or memoryless. Homework Equations None. The Attempt at a Solution The system is time invariant and is non-linear, but I don't understand why it is causal and has memory.
  30. K

    Control Systems, State space to Transfer Function

    Hi guys, Need a little help with an example my tutor and I are trying to work through. We're converting a dynamics system from a state space representation to a transfer function. This is where we are at so far... [s^2 + (C/Mb)S + (K1/Mb), -((C)S + K1)/Mb; -((C)S + K1)/Mw, S^2 +...
  31. I

    [NEED HELP ] Linear Systems Calculations

    Hi guys/gals, First post here - in need of some desperate last minute help. Today is my last day to study and I will have my final exam tommorow. I've been doing past papers all day, and there a few questions I have no idea/never seen before in my course material. Part (c) I have no idea what...
  32. C

    Signals & Systems Lectures Question

    Anyone knows any good online lectures on Signals & Systems theory?
  33. pairofstrings

    What type of category of systems does a computer PC fall under?

    Is it a linear system? Casual system? Please explain why and how.
  34. S

    Solving Systems of Linear Differential Equations

    1. x' + y' - x = -2t x' + y' - 3x -y = t^2 2. x' = Dx, y' = Dy 3. I eliminated x to get y alone by multiplying the first row by (D-3) and the second row by (D-1) (D-1)(D-3)x + (D-3)Dy = -2t(D-3) (D-1)(D-3)x + (D-1)(D-1) = t^2(D-1) then subtracted to get: (D+1)y =...
  35. S

    Solving Systems of Linear Differential Equations

    Hi all. Woohoo, I'm in diff eq now. Gosh, I've been on this board since Calculus I think. Sorry I usually only come around when I have a question. :\ Sooooo, Thursday my professor did an example of solving a system of linear differential equations with using the linear operator D...
  36. N

    Does close systems really exist?

    can anyone give me an example of isolated closed system?,bcoz for me there is nothing called closed system,all we can make out is to reduce the temperature of a system to such a critical point that there's hardly any interaction/exchange of energy b/w system and enviroment
  37. A

    Why is the minimum norm solution commonly used for underdetermined systems?

    Hi folks. This is something I've been wondering about for a while now. Is there a reason why taking the minimum norm solution is the standard thing to do for an underdetermined system, or is it just an arbitrary tie-breaking rule?
  38. P

    Learn More About Operating Systems: Linux, Pearl & More

    hey... This semester we were taught basic operating system functionality...like paging,segmentation,virtual memory,demand paging,disk allocation,memory allocation,disk scheduling,cpu scheduling,etc...form Galvin operating systems book...now i want to learn more about operating systems...such as...
  39. F

    Forced vibrations of damped single degree freedom systems?

    in a spring mass damper system subjected to a periodic force. the response of the system only depends on the force and the restoring forces caused due to the spring is ignored because the damper is assumed to have taken care of it. now it's here that my confusion originates. in a damped free...
  40. L

    Product of two systems of linear differential equations

    I have two systems of linear differential equations: \frac{dx}{dt}=Ax, \frac{dy}{dt}=By x,y are vectors of length n and A,B are nxn matrices. I have a third system defined by: \frac{dz}{dt}=-ABz Is there anything we can say about what the third system represents in terms of the first two? If...
  41. U

    How Can I Determine the Equivalent Transfer Function of Two Active LTI Systems?

    hello, If I have two LTI system in G1(s) and G2(s) and I know that for a certain fraction of the time period G1 is active and for the reminaing fraction G2 is active, then is there any method to get the equivalent transfer function ? Umat.
  42. D

    Close Packed Planes and Slip Systems

    I posted this in "Materials & Chemical Engineering", but it seems a little more active here. I'm confused with trying to find the slip systems of a simple cubic. I understand the slip plane would be along the plane with the highest atomic density (a close packed plane). But I don't quite get...
  43. W

    Quantum Mechanical systems considered in old QM

    Hello, I know that blackbody radiation was one phenomenon whose study contributed to the conceptual development of QM early on. My first question is, what other such systems were considered? I want to know this because I'm closely following the actual order of development of QM concepts, the...
  44. V

    Different Naming Systems in Textbooks: IUPAC Standards

    I have encountered different naming systems in textbooks. Ignoring cis/trans, for example, some textbooks would give the name 2-butene, while others give but-2-ene. Are they both acceptable? The newer textbook uses the second type of naming, while the older textbook uses the first...
  45. U

    Communication systems and entanglement

    Those who are against superluminal communication often choose to look at a single set of 'entangled' particles as an example of communication between A(lice) and B(ob). For example, Patrick Van Esch: 'EPR, density matrices, and FTL signaling' that sees the two particles as ‘clearly defined...
  46. bleist88

    Complete position function of time for multibody systems and gravity (Newtonian)

    Hi, {First off I should share my ultimate goal, which is to have a position function of time of several bodies, let's say in a solar system, so that the position of each body and the acceleration due to gravity on all the other bodies in the system are given at any time t. Although Kepler's...
  47. Z

    Physically, what is the difference between systems of ODEs and PDEs?

    What kind of systems do ODEs describe? What kind of systems do PDEs describe?
  48. pairofstrings

    Can Different Processors Share Memory in Embedded Systems?

    What are the basic elements in embedded systems? Can I use any microcontrollers, DSPs, and microprocessors in one systems. If yes, how is memory element linked with microcontrollers, DSPs, and microprocessors? On whose memory elements, codes are written? Which language is preferred for the codes?
  49. K

    Entropy in isolated quantum systems

    I'm still puzzled by Loschmidt's paradox. In quantum mechanics, an isolated system has a unitarian time-evolution which implies that the (von-Neumann-) entropy remains constant at all times. (Contrary to the entropy-increase due to mixing in isolated classical systems for example) So whenever...
  50. O

    What is the Kronecker index in dynamical systems?

    Hello all, I was wondering what is the Kronecker index in relation to dynamical systems. For instance a sample question would be find the Kronecker indices ind(0,x-F(x)) and ind(inf,x-F(x)) for the dynamical system {(dx/dt)=g(x,y),(dy/dt)=h(x,y)}. Thanks in advance.
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