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. A

    Laplace transform of anti causal systems

    The unilateral laplace transform integrates from 0 to infinity.Then how can i take laplace transform of exp(t)u(-t)?PS:I don't want to flip it and use time scaling property.
  2. R

    Zero order hold -- Discrete control systems

    I have some questions related to how a discrete control system is designed. One method is to design the controller in the continuous time domain, arriving at a transfer function (in the s-domain). After that, a transfer function for the ADC system must be taken into consideration. I will suppose...
  3. K

    The speed of a curve in different coordinate systems

    Hello, If for a curve in Cartesian coordinates ##||\dot{{\mathbf r}}||=\mbox{const}## (i.e. the curve is constant speed) will the speed of the curve change in cylindrical and spherical coordinates? Could someone experienced share how the transition from flat Euclidian space to curved space...
  4. B

    Are Alternative Kinetic and Hydro Storage Solutions Viable for Solar Energy?

    I have seen a lot of effort go into finding cheap, safe, high energy density phase change materials to store energy in the form of heat so power produced during the daytime may be delivered at night time. But I have an issue with storing energy in phase change materials. They rely on chemicals...
  5. W

    Can every countable number be represented in all numeral systems?

    Hi. This might be a stupid question (I'm studying engineering :p), but how do you prove that all numeral systems (binary, ternary etc.) can represent every countable number? I guess you will need to prove that any number ##N## can be written as ##N= S^0 n_0 + S^1 n_1 + S^2 n_2 + ...## where...
  6. M

    Mechanical principles rotating systems

    Homework Statement A shaft 2 m long rotates at 1500 revs min–1 between bearings as shown in FIGURE 2. The bearings experience forces of 5 kN and 3 kN acting in the same plane as shown. A single mass is to be used to balance the shaft, so that the reactions are zero. The mass is to be placed at...
  7. TrickyDicky

    Descriptions of time evolution: closed vs open systems

    The equivalence between descriptions of time evolution in QM are rigorously defined and proved for conservative systems as explained for instance among many other sources in Jauch's "Foundations of quantum mechanics" in the chapter 10. However, and an exception is the cited reference, it is not...
  8. R

    Where to Place a Fiducial Marker in SHM Systems?

    Homework Statement Where would be the perfect place to place a fiducial marker in a: mass on a spring system (vertical) and a simple pendulum? Homework EquationsThe Attempt at a Solution My teacher told me that for a simple pendulum it would be below the bob at equillibrium position because...
  9. Shackleford

    Ph.D. in Systems & Engineering Management

    I've decided that after I finish my MA Math next year I'm going to apply to this program. It's actually a hybrid program that allows people to take classes part time. They do have a modest residency requirement for two consecutive summers, and they're generous in transferring courses. I live in...
  10. G

    Converting 243 to Base 3 Using the Digit 5 | Number Systems Homework

    Homework Statement 243 is a decimal number. You must convert it to base n, where n will be computed using the digit (d) 5. For example if your digit (d) was "7" , then n is calculated as :n = d % 6 + 2 (where d = 7) = 7%6 + 2 = 3 Homework Equations None. The Attempt at a Solution n = d % 6 +...
  11. G

    MHB Convert 243 to Base 3 using Digit 5

    Guys Can you help me out, i don't know if I've done this right. Question: 243 is a decimal number. You must convert it to base n, where n will be computed using the digit (d) 5. For example if your digit (d) was "7" , then n is calculated as: n = d % 6 +2(where d=7)=7%6 + 2 = 3My Working: n =...
  12. D

    MHB Solve Force Systems II: Derivatives & Reasoning Explained

    Hello! :) Here's another problem that I want to fully understand how it was solved. The part that I'm having a hard time with is the taking-derivatives of some equations. Why did the solver decide to take the derivative of equation 2. And why the second derivative of equation 1 became like...
  13. L

    What stars/star systems can I see tonight?

    I live in Florida, and I've been looking for a website that will tell me what the sky will look like over my location and what each star is, but I can't find it. Anyone know if anything exists similar to what I'm describing? Thanks.
  14. M

    Calculate Currents & Power in 3-Phase Systems w/ Star-Connected Load

    Homework Statement Hello, I am given the following problem. A balanced three phase 4 wire supply has r.m.s. line voltage of 415V and supplies a star-connected load made of 3 impedances: Za = 10 - j10; Zb = 10 + j10; Zc = 0 + j8; Calculate the current phase and neutral currents, also the total...
  15. I

    Why Does AC Delay After Adjusting the Thermostat?

    I'm told the delay time (the time i turn down the thermostat and the time the AC kicks in) is a safety measure to let the coolant pressure equalize. I don't really understand why.
  16. O

    Apparent 'stillness' of macroscopic systems

    Hi fellow PFers, long time reader here. I have a query that was motivated by a comment on another thread (“Decoherence question”). It is about the quantum properties of decohered macroscopic systems. In my (incomplete and perhaps misapprehended) understanding, a macroscopic object, say a chair...
  17. Borek

    Simulation of mechanical systems - FLOPS required?

    I suppose some of you know the game called "Bridge Builder" (or Pontifex, or clones). I need some help determining how many FLOPS are required during the simulation and how do they scale with the bridge size (number of elements). Some of these bridges contain hundreds of elements and tens of...
  18. B

    Understanding Vapor Pressure in Open Systems

    I learned that vapor pressure is defined in a closed system, but some questions ask me to consider vapor pressure in an open system. How is vapor pressure defined exactly? And where is this pressure acting against? Also why is it that at the boiling point, the vapor pressure and the atmospheric...
  19. C

    Compound Interest Systems of Equations Problem

    Homework Statement Romeo was given a gift of $10,000 when he turned 16. He invested it at 3% per annum. Three years later, Juliet was given $10,000, which she invested at 5% per annum. When will the two amounts be equal in value? Homework Equations Compound Interest Formula Total =...
  20. G

    Dynamic Systems - DE with Unit Impulse

    Homework Statement y(t) = e^{a(t-t_{0})} y(t_{0}) + \int_{t_{0}}^{t} e^{a(t-\tau)}b \dot{u} (\tau) d\tau u(t) = \delta(t) = \frac{1}{2} c^{3} t^{2} e^{-ct} where c >> |a|, t_0 = 0, and y(0) = 0 Find y(t) and represent the unit impulse, delta, in the solution. The remaining terms should not...
  21. B

    Mechanical advantage ideal systems

    Homework Statement An engineer with mass 100 kg has designed an ideal mechanical advantage machine shown below. Platforms 1 and 2 are attached to the machine. When he steps on platform 1, platform 2 rises straight up. The maximum weight that he can lift using his machine in this manner is...
  22. G

    Control Systems Engineering - Block Reduction Help

    Homework Statement Hello, I'm trying to reduce the following block diagram Homework EquationsThe Attempt at a Solution I appear to be having some issues in doing this. The first thing that I did to reduce this block diagram was to take the forward path that has 2/(s+4) with negative...
  23. ognik

    Orthogonal coordinate systems - scale factors

    Homework Statement Start from the 'relevant equation' below and derive $$ (1) \frac{\partial{\bf{\hat{q}}_{i}}}{{\partial{q}}_{j}}={\hat{q}}_{i}\frac{1}{{h}_{i}} \frac{\partial{h}_{i}}{{\partial{q}}_{j}}, {i}\ne{j}$$ $$ (2) \frac{\partial{\bf{\hat{q}}_{i}}}{{\partial{q}}_{i}}= -\sum...
  24. Etheryte

    Solving Linear-Nonlinear Systems

    1. Homework Statement In a chapter in a book I'm studying from, they introduce quadratic inequalities (all conics, not just parabolas) but don't go over how to deduce which portion of the graph should be shaded. Considering there's two variables involved in these inequalities, I've been having...
  25. ORF

    Question about "bound systems"

    Hello If we have a system of several particles bound between them, we often separate the movement of CM from the degrees of freedom of the bound system. Is the degree of freedom of the CM linked to other degrees of freedom of the bound system? Equivalent questions: can we unbound (untie...
  26. G

    Programs Best degree to go into systems engineering?

    I am an engineering student at McMaster University who is interested in going into systems engineering. Unfortunately, our school does not offer this as a major. However, the mechatronics curriculum has a lot of systems classes in it, so I was thinking of taking that. The problem is, I've heard...
  27. O

    Good books on propulsion systems?

    Any recommendations for books on Propulsion Systems that arent $100+?
  28. H

    Finding Power Ratio of Two Pulley Systems

    Homework Statement Part C: http://imgur.com/mFlXGZs Homework Equations Power = τω The Attempt at a Solution P1/P2 = τ1ω1/τ2ω2 = (T1/T2) * (ω1/ω2) T1/T2 is found in part B: r1/r2 (ω1/ω2) = vr1/vr2 (velocities are the same) = (r1/r2) (r1/r2)*(r1/r2) = (r1)^2/(r2)^2 The answer is 1.
  29. Shackleford

    Ph.D. Systems Engineering at CSU

    What do you guys think of this program at Colorado State University? I have a BS Math, and I'm working on an MA Math. Professionally, I've been working as a seismic processing geophysicist for just shy of two and a half years now. I might fall under the "applicable master's" category which would...
  30. Lobos

    Measurement Systems: Learn About Used Systems & Universe Measurement

    Does anyone know of a good website or book that provides every measurement system that is still being used to this day? For example, I want to know the "how and what" when it comes to measuring cells, atoms, subatomic particles, etc,. And another question, does anyone know if there is only one...
  31. Avatrin

    Matrices and systems of equations

    Hi I am now filling in what I perceive to be gaps in my knowledge. One of these problems is understanding why matrices can solve systems of equations. I do completely get Gaussian elimination to solve systems of linear equations. However, when using determinants and the like to solve, for...
  32. H

    Normal modes of continuous systems

    Homework Statement A room has two opposing walls which are tiled. The remaining walls, floors, and ceiling are lined with sound-absorbent material. The lowest frequency for which the room is acoustically resonant is 50Hz. (a) Complex noise occurs in the room which excites only the lowest two...
  33. V

    Is Universal Expansion Perceptible to Observers?

    Suppose that everything in the Universe - the radius of the sun, the astronomical units, radius of atoms, and everything else were to expand proportionately during the same period of time. This would mean also that the ratio of the time period of the various planets around the sun, and all local...
  34. P

    Mechanics (Non-inertial systems and Fictitious Forces)

    Homework Statement A sled slides from a slope with inclination α. A man standing on the sled ‘weighs’ an object with mass m using a spring balance. What weight does the balance indicate? I seem to be making it too complex, could anyone help me out with it? Homework EquationsThe Attempt at a...
  35. T

    Help me design an attendance process for lectures

    I am a member of a small group of physics graduate students in charge of a monthly series of public science lectures. The lectures are aimed at local high school students, and we have many high school teachers who encourage their students to attend by offering extra credit. The audience of each...
  36. kq6up

    Enthelpy for Constant Pressure and Constant Volume Systems?

    I understand why entropy (a state function) is very useful in chemistry. Since most chemistry systems are at constant pressure, ##\Delta H=Q_v## from the derivation below: ##H=U+PV## ##dH=dU+dPV+PdV## ##dU=\delta Q-\delta W## ## dU=\delta Q-PdV## ## dH=\delta Q+dPV## ##dPV=0## ## dH=\delta...
  37. L

    ESD Standards for Components & Systems: HBM, CDM & Automotive Testing

    Is the ESD standard different for components(ICs) and systems. For Systems the standard I refer is IEC61000-4-2. For ICs, I am not sure. Does HBM and CDM apply to only components or does it apply to systems too? Is the Automotive ESD testing levels different than the industrial ones( 4KV...
  38. A

    Classical Looking for rigorous text on dynamical systems

    Hi, I'm looking for a modern rigorous text on (Hamiltonian) dynamical systems, perhaps with emphasis on perturbation theory. It should be in the same vein is Poincare's "methodes nouvelles", but modern.Thanks
  39. B

    Proving Equivalence of Iterative Refinement Equations for Linear Systems

    Homework Statement The question relates to iterative refinement. The idea is that the computer generates a solution to the linear system Ax=b which is inexact (due to roundoff errors), denoted by x0. You then iterate the algorithm given in (1) until it converges to (something much closer to)...
  40. terryds

    Understanding Normal Force Direction in Leaning Ladder & Cable Beam Systems

    I know that normal force is a reaction force. http://www.sumoware.com/images/temp/xzhhpaacgkdktjna.png In the leaning ladder problem, the normal force is perpendicular to the floor and the wall. But, in the cable and beam problem, why isn't the normal force perpendicular to the wall ...
  41. Mr Davis 97

    What are harmonic oscillators and physical systems?

    My question is how we describe a harmonic oscillate. Wikipedia says, "a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, F, proportional to the displacement, x." My question is, how is the harmonic oscillator a "system"? I thought...
  42. 2

    Confused about binary star systems?

    I was thinking about the motion of two stars in a binary star system, but there is something I cannot quite figure out. Suppose you have a binary star system with two stars masses m1 and m2 with m2>m1 so that m2 is closer to the centre of mass of the system. Then when the two stars are as far...
  43. A

    Relativity and kinetic energy, mass-energy systems

    Homework Statement An object with mass of 900 kg Is moving at a speed of 0.85c when it collides with an object at rest with mass of 1400 kgs. Find the speed and mass of the composite object. Homework Equations mc^2/gamma +mc^2/ gamma=Mc^2 The Attempt at a Solution My issue is that I am not...
  44. C

    What qualifications do I need for a career in embedded / control systems?

    After graduating with a BS in CS, I haven't really found anything in the field very appealing. However, after reading some things, I've found myself very interested in embedded / control systems. My question, is this a field I can pursue with only a BS in CS? Or should I go for a BS or MS in...
  45. I

    Systems of Equations word problems

    Hi, I have three systems of equations word problems. Can you help me? #1: The sum of three numbers is 32. The largest if 4 times the smallest. The sum of the two smaller numbers is 8 less than the largest. What are the numbers? I have tried to model this one. I got: _ + _ +_ = 32 Largest = 4S...
  46. M

    MHB How to Solve a System of Three Equations with Three Unknowns?

    How do I do: a + b = 3 -b + c = 3 a + 2c = 10
  47. S

    Event horizon in different coordinate systems

    Hi guys, I have a GR question. It is usually said that black holes have event horizons in which time freezes/stops relative to an outside observer. This happens in the Schwarzschild coordinate system. But are there any coordinate systems in which the coordinate time of the black hole and its...
  48. M

    LTI Systems, Delta Distribution, and more

    Hi, For my math methods 3 course, I am not quite sure which books to use. The course is based on the math methods book by Riley, Hobson, and Bence, and I don't particularly like it. Hence, I am looking for some alternatives. Especially for the Preliminaries section. I had a real hard time...
  49. M

    Could the Mayan Writing System Have Evolved Naturally?

    I'm just sending out a general call for people who have an interest in the study of writing systems and some knowledge on the subject. Linguists, anthropologists, sociologists (and even philologists if those still exist) are especially invited to reply. As a pump primer, I read the abstract of...
  50. B

    Applications of underdamped systems?

    Hi, We have covered underdamping, overdamping and critical damping in study, but I am unsure of a question, The question says "define the type of system that would give this response" (and there is an image of an underdamped wave). Are there systems that WANT to have underdamping?
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