What does linear analysis provide in terms of system response?
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Insight into why the solution has certain features and how the system might be modified.
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What does linear analysis provide in terms of system response?
Insight into why the solution has certain features and how the system might be modified.
What is the differential equation describing the system in Example 3.3?
˙y + ky = u = δ(t), with initial condition y(0) = 0.
What is the relationship between Y(s), U(s), and H(s) in Laplace transforms?
Y(s) = U(s) H(s), where U(s) is the Laplace transform of the input and H(s) is the Laplace transform of the impulse response.
What is the focus of the laboratory experiment described in Chapter 2?
The flow of water through two tanks.
What does C represent in the heating equation?
The thermal capacity of the house, measured in BTU/°F.
What does time invariance imply about the system's response?
If the input is delayed by τ seconds, then the output is also delayed by τ seconds.
What is the purpose of Chapter 3?
To discuss fundamental mathematical tools needed for analysis in the s-plane, frequency response, and state space.
What does the Laplace transform do?
Transforms differential equations into an easier-to-manipulate algebraic form.
What is the purpose of the Laplace transform in system analysis?
It simplifies the evaluation of the convolution integral.
What is the sifting property of the impulse?
∫₋∞^∞ f(τ)δ(t - τ) dτ = f(t).
What is the importance of obtaining the dynamic model of a system in control system design?
It helps to see how well a trial design matches the desired performance.
What parameters are used to compute a linearized model and transfer function in the two-tank system?
Pump flow (in cubic-centimeters per minute) to h2.
What is the heat rating of the furnace (K) given in the problem?
90,000 BTU/h.
How much does the house temperature fall when the furnace is off?
2 °F in 40 minutes.
What is the governing factor for the temperature in each room on the fourth floor of the high-rise building?
The cold airflow from the air conditioner produces an equal amount of heat flow q out of each room.
What happens to the output response when the input signal is scaled?
The output response will also be scaled by the same factor.
What can be identified from the transfer function?
Its poles and zeros, which indicate system characteristics including frequency response.
What does the principle of superposition tell us about system response?
We need only find the response to a unit impulse.
What does the illustration in Figure 3.1 represent?
Convolution as the response of a system to a series of short pulse (impulse) input signals.
What is the outflow rate when h2 = 15 cm?
200 g/min.
What is the effect of the impulse δ(t) on the system at t = 0?
It causes a change in the output such that y(0+) - y(0-) = 1.
What does it mean for a system to be time invariant?
If the input is delayed or shifted in time, the output is unchanged except for being shifted by the same amount.
What is the integral equation for the output of a dynamic response system?
y(t) = ∫_{-∞}^{∞} h(τ) u(t - τ) dτ.
What is the mathematical representation of an impulse signal?
δ(t), where lim ε → 0 pε(t) = δ(t).
How is the response to multiple short pulses determined?
By superposition, the response is the sum of the individual outputs.
What is the total response to a series of short pulses at time t?
y(t) = Σ (from k=0 to ∞) u(kε) h( t - kε).
Why are Fourier and Laplace transforms useful in studying LTI systems?
Because the response of an LTI system to an exponential input is also exponential.
What is the relationship between input signals and system output in convolution?
The system output is the result of the convolution of the input signals with the system's impulse response.
What does the principle of superposition state?
If the system has an input expressed as a sum of signals, the response can be expressed as the sum of the individual responses to those signals.
How is the output expressed when superposition holds?
y(t) = α1 y1(t) + α2 y2(t).
What does H(s) represent in the context of Laplace transforms?
H(s) is defined as the transfer function of the system.
What are the most common candidates for elementary signals in linear systems?
The impulse and the exponential.
What is the integral expression for causal systems when t = 0?
y(t) = ∫_{0}^{t} u(τ) h(t - τ) dτ.
What is the focus of Problem 2.27 regarding the two-tank fluid-flow system?
Finding the differential equations relating the flow into the first tank to the flow out of the second tank.
What is introduced when feedback is applied to a system?
The possibility of system instability.
What is the focus of the chapter mentioned in the text?
Linear analysis and computer tools for solving the time response of linear systems.
What change of variable is made in the dynamic response equation?
t - τ = η.
What is the unit-step function defined as?
Unit step 1(t) = { 0, t < 0; 1, t ≥ 0 }.
What are the unknown values to be determined for the house?
The values of C (thermal capacity) and R (thermal resistance).
What is the integral expression for H(s)?
H(s) = ∫(−∞ to ∞) h(τ) e^(−sτ) dτ.
What is a causal system?
A system where the output is not dependent on future inputs.
What is the output for a general input in a time-invariant system?
y(t) = ∫₋∞^∞ u(τ) h(t - τ) dτ.
What is the significance of short pulse inputs in system analysis?
They help in understanding the system's response through convolution.
What is the equation for heating a house as described in the text?
C dT_h/dt = Ku - T_h - T_o/R.
What is the significance of the equation ˙y + ky = u in relation to superposition?
It shows that superposition holds for the system modeled by this first-order linear differential equation.
What is the relationship between motion 'd' and the difference between T_act and T_amb?
Motion 'd' is proportional to the difference between T_act and T_amb due to thermal expansion.
What happens to the basic pulse as ε approaches 0?
It becomes more narrow and taller while holding a constant area.
What graphical tool is introduced for visualizing system models?
Block diagrams.
What is the Laplace transform of the output y(t)?
Y(s) = ∫_{-∞}^{∞} y(t) e^{-st} dt.
What characterizes a linear time-invariant (LTI) system?
The impulse response depends only on the difference between the time the impulse is applied and the time of observation.
What are the three domains to study dynamic response?
Laplace transform (s-plane), frequency response, and state space analysis.
What is the mathematical expression for a composite input in the context of superposition?
u(t) = α1 u1(t) + α2 u2(t).
How much does the furnace raise the temperature of the house in six minutes?
2 °F.
What happens to the output when the input is of the form e^(st)?
The output is H(s) e^(st), differing from the input only in amplitude H(s).
What assumptions are made about the rooms in the air conditioning problem?
All rooms are perfect squares, there is no heat flow through floors or ceilings, and the temperature is uniform throughout each room.
What does the convolution integral represent?
y(t) = ∫₀^∞ u(τ) h(t - τ) dτ.
What is the significance of poles and zeros in system analysis?
They help manipulate system characteristics in a desired way.
What are the two approaches to solving dynamic equations?
Linear analysis techniques for quick approximations and numerical simulation of nonlinear equations for precise analysis.
Under what condition does superposition apply?
Superposition applies if and only if the system is linear.
What is the solution for the impulse response of the system described?
h(t) = e^(-kt) for t > 0.
How is time invariance mathematically expressed?
If y1(t) is the output caused by u1(t), then y1(t - τ) will be the response to u1(t - τ).
What is the significance of the variable s in Laplace transforms?
The variable s may be complex, expressed as s = σ + jω, affecting both input and output.
How can the number of differential equations for the temperature in each room be reduced?
By taking advantage of symmetry to reduce the number to three.
What does the convolution integral represent in the context of Laplace transforms?
The convolution integral is replaced by a simple multiplication of the transforms, simplifying the analysis.
What test is used to determine stability in a system?
Routh’s test.
What does Figure 3.2 illustrate?
The representation of a general input signal as the sum of short pulses.
What is the convolution integral used for in the context of Laplace transforms?
It represents the relationship between the input and the impulse response of a system.
Under what conditions does Eq. (3.3) satisfy Eq. (3.2)?
If τ = 0 or if k(η + τ) = k = constant.
What is the principle used to solve for the response of a linear system to a general signal?
Decomposing the signal into a sum of elementary components and using superposition.
What mathematical tool is reviewed in Section 3.1?
The Laplace transform.
How can the effect of a collision between a bat and a baseball be summarized?
As the net velocity change of the ball over a very short time period.
What is the significance of the convolution integral in system analysis?
It describes the output of a system based on its impulse response and input.
How does the impulse response relate to the system's response to a general input?
The response is given by the convolution of the impulse response with the input.
What does it mean if h has values for negative time?
It means that the system response starts before the input is applied, indicating a non-causal system.
Why must care be taken when using the results of Laplace transforms?
The integrals of the transforms usually do not converge for all values of s and are only defined for a finite region in the s-plane.
What defines a short pulse p(t) in the context of the system?
A rectangular pulse having unit area, defined as p(t) = {1, 0 ≤ t ≤ ε; 0, elsewhere}.
What are the two attributes of linear time-invariant systems (LTIs)?