A new report on the Brooklyn Queens Connector or BQX—the streetcar that Mayor Bill de Blasio is apparently still determined to build—scales back the route by five miles, cutting out Sunset Park entirely, for a total of 11 miles of track. Despite the shortened proposed route, costs have crept up to $2.73 billion, from early estimates of $2.5 billion. And construction is not expected to begin until 2024. [ more › ] Gothamist https://ift.tt/2NBHFH1 August 31, 2018 at 12:54AM
Van der Pol’s differential equation is The equation describes a system with nonlinear damping, the degree of damping given by μ. If μ = 0 the system is linear and undamped, but for positive μ the system is nonlinear and damped. We will plot the phase portrait for the solution to Van der Pol’s equation in Python using SciPy’s new ODE solver ivp_solve . The function ivp_solve does not solve second-order systems of equations directly. It solves systems of first-order equations, but a second-order differential equation can be recast as a pair of first-order equations by introducing the first derivative as a new variable. Since y is the derivative of x , the phase portrait is just the plot of ( x , y ). If μ = 0, we have a simple harmonic oscillator and the phase portrait is simply a circle. For larger values of μ the solutions enter limiting cycles, but the cycles are more complicated than just circles. Here’s the Python code that made the plot. from scipy import linspace from ...
Comments
Post a Comment