What is the preferred ultrasound examination to evaluate vascular occlusions and blood flow dynamics?

For a LTI system with impulse response h[n] = (-3)n u[n-2], is the system stable?

An input signal x(t) = u(t+2) – u(t) goes through a LTI system with impulse response h(t) = u(t) – u(t-2) and generates output signal y(t), fill in the values for y(t), round to one decimal place. y(-3) = [ym3] y(-1) = [ym1] y(1) = [y1] y(3) = [y3] y(∞) = [yinf]

What is the active component that produces the sound energy and image in an ultrasound transducer?

Suppose the nonzero Fourier series coefficients of a periodic input signal x(t) with fundamental frequency ω0 = π/5 are a0 = 2, a1 = j, a-1 = -j, a3 = 4, a-3 = 4, and x(t) goes through a LTI system with impulse response h(t) = e-2tu(t) and generates output signal y(t). Which of the following is correct regarding the Fourier series coefficients bk of the output signal y(t)? Check all correct answers. 

For a LTI system with impulse response h[n] = (-3)n u[n-2], is the system causal?

Suppose the Fourier series coefficients of a periodic input signal x(t) with fundamental frequency ω0 = π/5 are a0 = 2, a1 = j, a-1 = -j, a3 = 4, a-3 = 4. Check all terms that contribute to the Fourier series sum to represent the periodic signal x(t):

Ultrasound frequency is expressed in units of 

Is the continuous-time signal x(t) = sin(3πt/5) periodic? If yes, what is the fundamental period?

What is the Fourier series coefficients a-1 of the periodic signal x[n] = cos(πn/4 – π/5) with period N = 8?