Engineering domain: Structure Design

## Task Description

This is a michell structure. 
Design domain is a 2D rectangular region in cartesian coordinate, with vertices at (0,0), (2,0), (2,1), (0,1). 
A vertically downward point load is applied at (1,0.5). Pin support is at (0,0.5) and roller support is at (2,0.5). 

The filter radius is R = 0.03*max(Lx,Ly).
The filter exponent is 3.


---

### Task

Your task is to:
- Obtain a topology optimized design that has minimum structural compliance and volume fraction not exceeding 0.15.
- Given the optimized design, output the corresponding minimum structural compliance, named C_y_hat, and also its volume fraction, named vf, in numerical numbers. Note that vf is in the range of [0,1].