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. J

    I don't understand conservative systems

    Homework Statement Look below. Homework Equations So my book says that you have a conservative system when E'(t) = [(1/2)m(x'(t))2 + V(x(t))]'(t) = 0. It gives an example of V(x) = -(1/2)x2 + (1/4)x4, whence setting y = x' gives E = (1/2)y2 -(1/2)x2 + (1/4)x4. According to the book, E...
  2. I

    Controllers, processors and operating systems in the car

    I search after information in these things: I think there are a lot of controllers and processors in the car but in which devices in the car they are and what them doing in these devices? What are the operating systems in the cars? What is algorithm for robust control?
  3. J

    For Statics:Simple Systems of Equations to Solve Equilibrium Problems

    Homework Statement I have a picture attached with this static equilibrium problem. (Solve system for Fac and Fab) Homework Equations Sum of x and y both=0The Attempt at a Solution I just don't have a systematic easy approach to solving these systems. Does anyone have one? From the picture...
  4. R

    The Earth Analemma and Orthonormal Coordinate Systems

    Hi. I have been researching the Earth-Sun analemma and I found this document about deriving the Earth-Sun analemma via orthonormal coordinate systems. Unfortunately I do not know very much about orthonormal coordinate systems and while I understand the first bit about elliptical angles, I...
  5. M

    The consistency of linear systems

    Homework Statement What conditions do x, y and z need to fulfill for the system of equations to be consistent? Homework Equations 2a + 3b + 5c = x a + 3c = y a - b + c = z The Attempt at a Solution Not quite sure. The notion of consistency was never discussed in class, nor is it...
  6. A

    Conservative forces and systems

    I read in a book that if the constraint forces do work, the system is conservative, else it's nonconservative. In that case, consider a system of two bodies moving in an elliptical path under gravitational attraction. Since the gravitational force is continuously doing work on the particles, by...
  7. M

    Laplace and Systems Control and Analysis

    Using Laplace can someone please show me in simple terms how i would solve the following function? This is a lecture example. The solution just shows the answer, nothing about how we get it or what it represents. I am finding this subject particularly difficult to come to grips with. δ(t-1)...
  8. L

    Want a book/notes that cover this syllabus (dynamical systems).

    I am looking for a book that covers these topics at a self-contained level for self-study (ie: a book designed for a short course on the subject or lecture notes): Things in bold are of most interest to me. I notice there are a lot of pure math books on this subject but I'm looking for...
  9. Jameson

    MHB Cammie's question from Facebook (finding a mixture through systems of equations)

    A girl scout troop has 20 pounds of candy worth 80 cents per pound. the troop wishes to mix it with candy worth 50 cents per pound so that the total mixture can be sold at 60 cents per pound without any gain or loss. how much of the 50 cent candy must be used? Solve by elimination.
  10. N

    Thermodynamic Reversible/Irreversible Closed Systems

    I am completely lost with this problem. How would I go about breaking it up into manageable components that so I won't get lost in the problem? Homework Statement A 2 m3 rigid storage tank containing 10 kg of steam is heated from 300 to 400 C by transferring heat from a hot reservoir at...
  11. H

    Mind blown by mechanical systems (2nd order)

    Homework Statement B, K, M Homework Equations 1. xs(t) -----spring ----mass-----damper-----fixed, derive DE for x of mass given :2. F - > M -----spring-------damper ---- fixed in series, derive the DE for velocity of spring The Attempt at a Solution 1. ma = -k(x-xs) -...
  12. V

    Delayed power on to multiple systems with a single switch?

    Hey gang, I am trying to figure out a solution to a small problem i have.. and it is probably really simple, especially to you guys. I want to be able to power on a series of monitors and then a PC, with a small delay, by turning the main power switch on. To give a better...
  13. B

    Control Systems Engineering : Response of a system to a Harmonic Input

    Homework Statement In my notes it is stated that an integrator adds a phase lag of -Pi/2 and thus can cause instability. I want to understand what this really means and am deviating from the notes somewhat so do not know if I am barking up the wrong tree. Homework Equations Given a...
  14. M

    First and Second Order Systems - Classical Analysis

    This was a lecture example and it has confused me. Can someone please help explain it? If we have the following fist order system: τ.dx/dy+y(t)=x(t) where τ=c/k where "k" is the spring stiffness and "c" the linear damper coefficient and τ is a time constant. For the unforced case x(t)=0, we...
  15. B

    Control Systems Engineering : Masons Gain

    Homework Statement Here is the system I am looking at Homework Equations So I worked out a formula for the steady state error and put it in a form similar to masons gain formula The Attempt at a Solution But when I try and draw a block diagram and work out e I get...
  16. F

    Linear Algebra - Linear Systems and Matrices

    Homework Statement Suppose we know that a linear system Ax = b has a unique solution. What can we say about the solutions of the linear system Ax = 0? a) It has the same solution. b) The solution to Ax = b is also a solution to Ax=0, but there may be other solutions. c) Ax = 0 has a...
  17. A

    Impulse Response of Causal Systems

    I am reading "Linear System Theory and Design" by Chen and he says (in what follows g(t,tau) is the impulse response function): If a system is causal, the output will not appear before an input is applied. Thus we have Causal <==> g(t,tau) = 0 for t < tau. However, this seems incorrect...
  18. A

    Best Signals and Systems book?

    What is the best book out there for Engineering Signals and Systems? One that is clear & easy to understand and has many different problems with solutions. The book I am using has no solutions and there is no way to check my work. I hope someone knows a similar book...
  19. Z

    How Do You Calculate the Moment in a Force-Couple System at a Pivot Point?

    Homework Statement A force F of magnitude 50 N is exerted on the automobile parking-brake lever at the position x=250 mm. Replace the force by an equivalent force-couple system at the pivot point O. Picture: http://i.imgur.com/dJGtvAo.png Homework Equations M=F*d The Attempt at a...
  20. Mandelbroth

    Logarithms in Systems of Equations

    Homework Statement Consider the system... y=e^{-x}+1 \\ y=2+lnx The Attempt at a Solution I don't think there is a "pretty way" (algebraic manipulation) to do this. I simply found the point where the plots intercepted, getting the solution set (0.62745018..., 1.5339409...). Is there a...
  21. Greg Bernhardt

    Classical Classical Dynamics of Particles and Systems, by Jerry Marion and Stephen Thornton

    Author: Stephen T. Thornton (Author), Jerry B. Marion (Author) Title: Classical Dynamics of Particles and Systems Amazon Link: https://www.amazon.com/dp/0534408966/?tag=pfamazon01-20 Prerequisities: Calculus, Ordinary and Partial Differential Equations, Introductory Physics Level...
  22. N

    Time dependent forcing and nonlinear systems

    Hi, I'm trying to find a toy (i.e. analytic) example of a nonlinear system that has very different behavior for two different types of forcing: 1) \frac{\partial u(x,t)}{\partial t}+ N(u(x,t)) = F(x) where u(x,t) is the dependent variable, N represents some nonlinear operator with only...
  23. M

    Examples of systems that generate C-EMF?

    Hi,Do you know systems that generate C-EMF? Set ups like an Electric Motor? What other system do you have in mind? Another thing. I know that CEMF is caused by a changing electromagnetic field. How can an electromagnetic field be changed? Please elaborate! Miyze,
  24. E

    Thermo Question: The math behind systems in thermal contact

    Hi! I am reading Molecular Driving Forces, 2nd ed., by Dill & Bromberg. On page 53, example 3.9, we consider why energy exchanges between two systems from the point of view of the 2nd law. We consider two separate systems. Each has ten particles, and each particle has two possible energy...
  25. S

    Software to solve Nonlinear Systems (ineq and eq)

    Hi everyone, I've got an optimisation/computing question. I have a system of nonlinear equalities and inequalities, which I've written below for reference. It's the conditions for a minimiser of a Karush-Kuhn-Tucker problem. Would anyone be kind enough to explain how I could use software to...
  26. D

    2D Systems and 4D Minkowski Space: Exploring Path Integrals

    The combination of special relativity and quantum mechanics in a single framework makes our understanding of such systems to be true only in 4D, Minkowski space...I have noticed that recent published work concerning 2D systems and I am not sure about this reduction of 4D to only 2D, does it mean...
  27. R

    Schools Studying Chaos Theory & Dynamic Systems for Postgraduates

    Hi everyone, it's been a while since I visited here. However, I now find myself in need of help as to how to best go about studying something related to chaos theory and dynamic systems in postgraduate school. I'm currently in my third year of physics and my first question would be what...
  28. R

    Residual Gas in High Vacuum Systems

    Homework Statement What is the likely main residual gas constituent of a high vacuum system (HV) (P~1x10-4 Pa) and where does it come from? Explain how the vacuum may be improved to give ultra-high vacuum (UHV) (P~1x10-8 Pa). What is the likely main residual gas constituent of ultra-high...
  29. P

    Solve 3x-y+2z=4 - Help for Newbie

    am not a math guru :P,am a newbie even if this should be solved by a newbie as well, Id like u guys to help me out to solve this one : 3x-y+2z=4 Im really needing this, thank you all.
  30. O

    MHB Calculating partial derivatives in different coordinate systems

    let f = x2 + 2y2 and x = rcos(\theta), y = rsin(\theta) . i have \frac{\partial f}{\partial y} (while holding x constant) = 4y . and \frac{\partial f}{\partial y} (while holding r constant) = 2y . i found these partial derivatives by expressing f in terms of only x and y, and then in...
  31. U

    Functions in coordinate systems

    Hi all. What does it mean that a function in polar coordinates may not be a function in Cartesian coordinates? For example, r(\theta) = 1 + \sin\theta is a function because each \theta corresponds to a single value of r. However, in Cartesian coordinates, the graph of this function most...
  32. nukeman

    Regards to chemicals/drugs: How do delivery systems work?

    Hey all, How do drug delivery systems work? Lets say I have a drug that I want to test out, let's called it DrugX. Now drugX will not work by it self because there is something in the body that kills it right away, or it can't bypass the bloodbrain barrier. Now, I have this chemical...
  33. S

    Nonlinear Systems & Weighted Sum of Impulses

    Hello, my question is that almost all textbooks say that a linear system will give the output to a weighted sum of impulses which equals the superposition of scaled responses to each of the shifted impulses. But if we apply the same input which is a weighted sum of impulses to a non linear time...
  34. S

    Is Signals & Systems Memoryless/Linear?

    1) y(t)=dx(t)/dt Is this system memoryless? 2) y(t) = 0 if x(t)<0 x(t) + x(t-2) if x(t)>=0 Is this system linear? Thankyou :)
  35. H

    Understanding the Contradiction: Spin Rotation in Quantum Systems

    This has been a contradiction in my brain for some time. If I want to rotate one nuclei (spin 1/2), with say an applied magnetic field B and RF pulse (at the appropriate larmor frequency), how does the spin actually rotate? I thought it can only take on discrete values of 1/2 or -1/2...
  36. E

    MHB Continuous-time and Discrete-time systems, Schur conditions, Routh-Hurwitz

    Hi guys, I hope one of you can help me out with the following problem. I hope I posted the problems in the correct section. Problem: Consider the following continuous-time and discrete-time systems with respect to a common 2X2 matrix A: x˙ = Ax (1) is a continuous- time system xt+1 = xt +...
  37. Vorde

    Basis/Unit vectors in other coordinate systems

    We all know the ##\vec{i}##,##\vec{j}##,##\vec{k}## unit vectors for Cartesian space. But I've never been shown basis unit vectors in other coordinate systems. Do basis vectors exist in other coordinate systems? And if so what are they?
  38. P

    Lightning Protection Systems: Direct vs Indirect Strokes & EMPs

    About two weeks ago, I wanted to find out more about the design of lightning protection systems. In particular, I wanted to figure out what gage of wire would be necessary for linking a lightning rod to earth-ground. What I had learned is that the gage of the wire would have to be extremely...
  39. M

    Cellular radio systems questions

    With regards to cellular radio systems1. how many bits of information does each cycle of a sinewave carry on a minimum channel? modulator characteristics 2. A system has narrowband fm characteristics.. name me a rule which is an approximate technique to find the necessary freqeuncy deviation...
  40. O

    Looking for a common solution of two systems

    Given two systems, Ax=b and Cy=d, for nxn matrices A and C, and n-dimensional vectors b and d, each of which has at least one solution, it is know that one solution is common to both (satisfies both equations). Could such solution be z found by solving Az+Cz=b+d? I understand that a common...
  41. G

    Contemporary Issues In Industrial Systems Engineering?

    Hello Physics Forums! I need a bit of help. I'm aware that this is not a HW thread, but your help is greatly needed. This could be posed as a general discussion question if this is of any concern. An assignment requires that I have to do research of several contemporary issues in ISE...
  42. C

    Probs and Stats problem with Queuing systems

    1. Homework Statement [/b] A barber shop has two chairs to cut hair and 10 people per hour enter the barbershop to get a haircut. . The average time it takes to get a haircut is 6 minutes. On this particular day, only one barber is cutting hair. Customers that enter the barber shop and use the...
  43. T

    Are these two systems non- causal?

    Homework Statement y(t) = ∫∞-∞x(λ) dλ AND y(t) = ∫t-∞x(5λ) dλ Homework Equations The Attempt at a Solution They're both non-causal right? because in the first one the input can be less than t and in the second one it IS less than t? Thanks
  44. E

    Invariance of vectors due to changes in coordinate systems

    Homework Statement How do I know that vector is invariant to changes of coordinate systems if i only have the components of the vector and not the basis vectors? Homework Equations let the vector in reference frame 1 be ds and the same vector in the reference frame 2 be ds1 The...
  45. O

    Schools Best grad schools for control theory/control systems engineering?

    I've been trying to search for some sort of list of top schools for graduate study in control theory. While there are rankings available for electrical engineering in general, I'm having a hard time finding rankings for specific specializations. So far I've heard Carnegie Mellon, Stanford...
  46. D

    MHB Bifurcations of dynamical systems

    Something doesn't seem right in regards to my analysis of the Jacobian. What about when $a=0$ at the second fixed point? \begin{alignat*}{3} x' & = & y - ax\\ y' & = & -y + \frac{x}{1 + x} \end{alignat*} First, we need to determine the fixed points in the system. So let \begin{alignat*}{3} y -...
  47. K

    Calculators TI-36X Pro solving systems of equations with complex numbers

    Hello all, I was wondering if there was a way of solving a matrix on a TI-36X Pro that has complex numbers in it. Every time I try, it just says "invalid data type". Is there any way of getting around this? Thanks! Robert
  48. STEMucator

    Is the book incorrect here? Systems of diff eqs.

    Homework Statement Here is the question from my book along with their solution to the problem : Part 1 : http://gyazo.com/6467751155edcefec6cc583d164d2ae7 Part 2 : http://gyazo.com/d91752f0a18a72af96f6afc74117f011 Part 3 : http://gyazo.com/7a17dbca3e414d0ddc8458abce2eda9c Homework Equations...
  49. Z

    Standard Form for second order systems.

    Suppose there's a system with given uncertain parameters. And I would like to obtain certain Rise time, max. over shoot, settling time by adjusting those parameters. Let's say this is the second order system; T(s) = (ks + c) / (s2 + as + b) First of all; for a second order system there...
  50. W

    Mathematical treatment of signals and systems

    Hi there, I am looking for books that treat signals and systems from a mathematical perspective. When I say "signals and systems", I am referring to the typical second/third year material taught in EE programs: system characteristics (causality, memory, stability), LTI systems, linearization...
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