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

    Flux in different coordinate systems

    I have an electromagnetic field with a Poynting vector that has the following form in spherical coordinates: $$\bar{P}(R,\phi,\theta)=\frac{f(\phi,\theta)}{R^2}\bar{e}_{r}$$ The exact nature of f(\phi,\theta) is not known. Suppose I measure the flux of this vector field by a flat area...
  2. S

    Quantum transistors in aircraft aileron control systems

    hello all, i need some help on this one. i want to do an article about the posible aplications of quantum entanglement in aircraft flight control systems. i want to entangle two transistors, put one of them at the ACE - actuator control electronics (probably) in the pilot's cabin and the other...
  3. L

    Differential operators in arbitrary coordinate systems?

    Hi, physics undergraduate here. I don't know much about differential geometry yet, but I'm curious about this idea: Say I encounter a boundary value problem, and I'm not sure what coordinate system would be 'easiest' to solve the problem in. Is there some way to put the differential...
  4. LeonhardEuler

    Theory of Systems of Rays question

    Hello everyone. I'm looking through an old book on optics and something there has me really confused. I attached the two pages I'm referring to, or you can find them here: http://www.maths.tcd.ie/pub/HistMath/People/Hamilton/Rays/ as pages 14 and 15 in the pdf. Basically, what's going on is...
  5. G

    Definition of entropy of complex systems is existed?

    Common extensive quatities such as mass, charge, volume can be defined for general systems. I can imagine that we can measure and define them without any problem in case of any kind of complex system as well. However, I do not know the general definition of the entropy, only the thermodynamic...
  6. B

    Mathematica Mathematica: Solving Linear Complex Systems

    Good evening, I am currently trying to use Mathematica to find the symbolic solutions to a set of complex linear equations. I have never used Mathematica for such a task before and am finding it quite difficult. Let me state the problem...
  7. matqkks

    MATLAB Matlab or computer algebra systems

    How does Matlab or computer algebra systems find derivatives of functions? Is it correct that they use matrix transformation?
  8. T

    Maple Calculating Time Derivatives of Terms with Autonomous Systems

    Hi guys I have 5 term which each term includes three function of time (autonomous system ), i want to obtain time derivative of each term as other terms for example if i define each term as a dimensionless variable , e.g. x , y , z , v , w , i want to know dx/dt = as a combination of x , y ...
  9. S

    MHB Dynamical Systems and Markov Chains

    Prove that if \(P\) is a stochastic matrix whose entries are all greater than or equal to \(\rho\), then the entries of \(P^{2}\) are greater than or equal to \(\rho\).
  10. I

    Systems science/theory and downward causation

    I've been reading a bit about systems science/theory and I understand that in some fields it sometimes pays off to look at how the whole systems behave as opposed to how the individual parts that comprise the systems work. However, there seems to be a certain aspect of systems theory known as...
  11. M

    Why did Bohr's model work for 1 electron systems?

    If I am not mistaken the Bohr model had 3 main problems: the assumption that the electron moves in fixed orbits, the angular momentum assumption's violation of the Heisenberg uncertainty principle, and finally the restriction of the validity of the model for only 1-electron systems ( i.e...
  12. P

    Under damped and Over damped systems Examples

    hey, could you help me with a few examples of Underdamped and Over damped systems?
  13. U

    Integration in two different coordinate systems

    Hi all. I am very puzzled by the following. Let x_1 and x_2 be two coordinate systems related by x_1=1-x_2. Now if y(x_1) = x_1 and z(x_2) = 1-x_2, then clearly y(x_1)=z(x_2). Now integrating the function in each coordinate system gives Y(x_1) = \int y(x_1) dx_1 = \int x_1 dx_1 =...
  14. R

    Signals and Systems - Power and Energy level signals calculation

    Homework Statement http://i.imgur.com/j8JdV.png Homework Equations http://i.imgur.com/Wobmo.png The Attempt at a Solution I wasn't really sure where to start with. Can energy level be calculated at any of these, since the signal stretches to infinity? I'm very thankful for any...
  15. chemisttree

    News A123 Systems files for bankruptcy

    After receving $249.1 million grant from the US Department of Energy and $125 million in tax credits and incentives from the Michigan Economic Development Corp., A123 Systems is filing for Chapter 11. What remains to be seen is how the debtors will run the company and if the jobs promised here...
  16. H

    Anyone have experience working in/with Complex Systems?

    Complex systems is somewhat of a newer/emerging field. I can't do a good job characterizing it, but it is quite interdisciplinary and relies on heavy mathematical and computational modelling of various... well, systems that are complex. (Anything from ecosystems, to stock markets, to weather)...
  17. 3

    Solving a Vertical Winch System

    Hey! I'm having some problems with this question: An electric winch is used to raise a 40-kg package and a 10-kg package vertically up the side of a building as pictured in the diagram. The magnitude of the frictional force acting between the wall and the 40-kg package is 60N. The angle the...
  18. R

    Designing a PID controller - control systems engineering

    Homework Statement I am given the transfer function Gp (s) = 1/(s+16) and I have to design a controller of the form Gc (s) = K(1 + 1/T*s) (which is a PID controller) To meet the following requirements: Maximum steady state error to a steadily changing desired position = 5% Maximum...
  19. andrewkirk

    Problem in Logic - Hilbert Systems

    Homework Statement In a Hilbert System, prove: \phi[x|m] \rightarrow\forall y((y=m)\rightarrow\phi[x|y]) where \phi is a formula, y, x are variables and m is a constant. \phi[a|b] denotes the formula obtained by substituting b for a in \phi This problem crops up in my attempting to prove...
  20. M

    Solving Pulley System Questions: Tensions, Weights, and F=ma

    In the figure below, M2 has more mass than M1 and M1 has more mass than M3. The questions refer to the magnitudes of tensions and weights. There is friction between the horizontal plane and M2 (mu_k not equal to 0). M2 is observed to travel at a constant speed. Assume that the pulleys are...
  21. M

    Solving Pulley Systems with Multiple Masses and Angles

    Homework Statement A crate is pulled up using frictionless pulleys in the manner shown in the figure. The angle is 45 degrees. The masses are, for the small pulley, m1=3.5 kg, for the traveling pulley, M2=6.5 kg, and for the crate, MC=44.2 kg. What is the minimum tension with which the...
  22. G

    Understanding Pressure Loss in Closed-Loop Cooling Systems

    A certain part of a closed loop cooling water systmem has to have some of the pipes made to have a larger diameter to allow more flow. Does this mean though that the overall pressure in the system will drop? I know the headloss in the widened pipe will decrease and flow increase. But will you...
  23. T

    MHB Setting up systems of equations

    I have this problem in my book: Ann had 20(Cash) less than Betty. Ann spent 3/4 of her money, while Betty spent 4/5 of hers. Then Ann's remainder was 5/6 of Betty's remainder. If Ann had x(Cash) originally, form an equation in x and solve it. And this solution in the answer key: x=Ann's...
  24. G

    Can Isolated Systems Under an Energy Constraint Exhibit Chaotic Behavior?

    For systems under an energy constraint (a conserved Hamiltonian that is a function of the q's and p's in generalized coordinates), is it possible for it to behave chaotically (chaos by its dynamical definition), or will it always have some equilibrium it tends towards?
  25. F

    Mathematica Solving systems of nonlinear ordinary equations in Mathematica.

    I'm trying to solve a system of five nonlinear equations (degree 7) in Mathematica: Solve[{q (a^2 + b^2 (3 q^2 + r^2 + 8 t^2)) ((e - q)^2 - R^2 - 4 T^2)^2 + q ((e - q)^2 + R^2 + 4 T^2) - 2 (e - q) (r R + 4 t T) == 0, R (a^2 + b^2 (3 R^2 + (e - q)^2 + 8 T^2)) ((e - q)^2 -...
  26. C

    Number systems and their effect on physics

    The Egyptians were known for using base 6 while base 10 is more popular presumably because of the number of fingers we have. How much does the value of the base number of a mathematical system affect the underlying math used to describe physics? Would we still be able to arrive at the same...
  27. B

    MHB Using linear systems to solve problems (5)

    Rajah earns an hourly wage plus tips. One week he worked 12 h and made a total of \$117. The next week he worked 10 h and earned the same amount in tips as the week before, for a total of \$110. What is Rajah's hourly wage? I need help getting the two equations
  28. B

    MHB Using linear systems to solve problems (4)

    Sabrina has two part time jobs delivering flyers. She earns \$9/h at her weekday job and \$12/h at her weekend job. Last week s he worked 23h and earned a total of \$231. How many hours did she work at each job?
  29. B

    MHB Using linear systems to solve problems (3)

    Rajah earns an hourly wage plus tips. One week he worked 12 h and made a total of \$117. The next week he worked 10 h and earned the same amount in tips as the week before, for a total of \$110. What is Rajah's hourly wage?
  30. B

    MHB Using linear systems to solve problems (2)

    Provincial Express charges \$4, plus \$1.50/kg, to deliver a package overnight. The Package people charges \$5, plus \$1/kg. When is Provincial Express less expensive to use?
  31. B

    MHB Using linear systems to solve problems (1)

    Sook-Lee wants to rent a car for a day so she can visit her sister at university. She has called two car rental agencies. Rent-a-Heap charges \$50 per day, plus \$0.12/km. Kurt's Rent-a-Car charges \$40 per day, plus \$0.20/km. At what distance will the cost of renting of a car be the same from...
  32. F

    Linear systems: zero, one, infinite solutions

    Hello forum, why does a system of linear equations really have no solution or one unique solution, or infinite solutions? What forbids a system to a finite number of solutions? thanks fisico30
  33. A

    Which systems satisfy Hamiltons principle

    I have had similar questions posted, but I am not quite sure on this one and it seems that my textbooks have trouble agreeing completely aswell. As far as I understand it: Hamiltons principle: δI = δ∫Ldt = 0 is only satisfied for systems, where the generalized forces can be put in a...
  34. FOIWATER

    Control systems question involving laplace transforms

    I have narrowed down a control systems question I am doing to the following function in the S-domain.. numerator = (5s+1) denominator = (s+3)(3s+2)(s^2) Using partial fraction expansion - I compute A = 14/63... D = 1/6... B = -2.25 And I can go no further - because both MATLAB and MAPLE...
  35. R

    How to solve linear first order variable coefficient systems?

    1. how do i solve X'(t)=A(t)X(t) Homework Equations I know of this equation: x(t) = x_0 \exp\left( \int_{t_0}^t f(\xi) \, d\xi \right) but i think that I'm using it wrong. The Attempt at a Solution i have the following mathematica code: A= x = MatrixExp[Integrate[A, {t, 0, s}]].{1, 0,0,0}...
  36. N

    Linear Systems: Linear combinations

    Homework Statement Determine if b is a linear combination of a1, a2, and a3. a1= [1,-2, 0] a2 = [0, 1, 2] a3 = [5, -6 8] b= [2, -1, 6] The Attempt at a Solution Alright, well I used an augmented matrix to solve the problem, and after reducing it completely, the matrix looked...
  37. X

    Introductory Systems and Signal Processing resources?

    I don't have an explicit problem to be answered per se, but what can I do about my signals processing course? We're only into our 4th week of school, and already my professor has had several lectures on Fourier Transforms. I am lost. Besides basic calculus, trig, and complex number theory...
  38. A

    Engineering Control Systems: How would you find the State Equations for this simple circuit?

    Homework Statement Consider the electrical circuit shown: http://imageshack.us/a/img525/8163/p1circuit.png Let the state variables be x1(t)=Vc(t), x2(t)=iL(t), and x3(t)=Vc(t); output is Vo(t). Write the state-space equations in matrix form and find the transfer function, T(s)=Vo(s)/Vi(s)...
  39. O

    How do the laws of thermodynamics affect hydrogen on demand systems?

    I was wondering if someone could explain how the laws of thermodynamics apply to these so called hydrogen on demand systems and or how these laws govern the operations of these systems. Physics is my next college course but, I am not asking this for any assignments I have, just a personal interest.
  40. M

    Computer Engineering vs Computer Systems Engineering

    Hi, I'm currently a sophomore at a 4 year university. I'm going to be switching my major to something in engineering. (I've talked to an advisor to verify that I can do this without postponing my graduation. My school offers an undergraduate degree in Computer Systems Engineering and a masters...
  41. J

    Solving linear systems using fourier transform

    I want to use Matlab and Fourier transforms to solve linear systems and am attempting to implement a very simple linear system (with the idea of implimenting a much more complex one later) that I can't seem to get working. The system will take the derivative with respect to time of the input as...
  42. H

    Systems Engineering and Management MS or Supply Chain Analyst MS?

    Straight up, I want to be a Chief Office eventually. I can concentrate the SEM MS into many categories--probably choosing healthcare for a few reasons--including their high salary and necessity. However, what about Supply Chain Management...honestly, I don't like the idea of working in a...
  43. D

    How to Start Embedded Systems Programming

    I want to learn some embedded systems programming on my own and explore it as a career option. Where should I start? Book recommendations? I have programming experience in assembly, C and higher level languages, and I've taken one computer architecture course. I love my linux, so I'm interested...
  44. bcrowell

    Effect of cosmological expansion on bound systems in realistic cosmologies

    This paper dates to 1998: Cooperstock, Faraoni, and Vollick, "The influence of the cosmological expansion on local systems," http://arxiv.org/abs/astro-ph/9803097v1 They show that systems such as the solar system, galaxies, and clusters of galaxies experience nonzero effects from cosmological...
  45. X

    Postdoc for vacuum compatible microfluidic systems

    Job Description: The goal of this research is to develop a multimodal analytical platform. The postdoctoral scientist will develop microfluidic systems for cultivating and characterizing biofilms and bacteria using multiple analytical techniques. The main workload will be dedicated to the...
  46. M

    Simple Question about the Solar System/Planetary Systems

    In our solar system, the more massive planets orbit the Sun in between less massive planets. I was wondering if it was by coincidence or if it's dictated by some universal law in all planetary systems. One would think more massive planets would be closer to the sun but I'm clearly missing...
  47. V

    Control of Quantum Systems: Need suggestions

    Hello All, I am new to the field of "Control of Quantum Systems". However the things that I know are: Controlling quantum mechanical systems is a challenging job because if want closed loop (feedback) control and measure the systems's output, the output itself changes (because in quantum...
  48. T

    Relationship between two coordinate systems.

    Homework Statement http://img15.imageshack.us/img15/1671/capturetwy.png The Attempt at a Solution Could someone please explain what is meant by "if v is constrained to 0"? Also how do you find a relationship between two axis of different coordinate systems? I really have no clue where...
  49. H

    Mechanical advantage and force analysis of complex pulley systems

    Homework Statement These are two of the excercises where I'm supposed to calculate the mechanical advantage of the pulley systems. Excuse the crude MS paint drawings, I do not have access to a scanner or a proper camera. The red dots are where two cables connect. The Attempt at a...
  50. O

    Coordinate Systems: When to Make the Switch?

    We may solve a function or check a theorem but sometimes the mathematics is easier when we switch from different coordinate systems. What can we look for that tells us changing is a good idea?
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