## estimate the direction in which the blank was cut.

It was stated in Section 7.7.1 that the thicker the sheet metal, the higher is its curve in the

forming-limit diagram. Explain why. In forming-limit diagrams, increasing thickness

tends to raise the curves. This is because the material is capable of greater elongations since

there is more material to contribute to length.

2. Inspect the earing shown in Fig. 7.57, and estimate the direction in which the blank was cut.

The rolled sheet is stronger in the direction of rolling. Consequently, that direction resists

flow into the die cavity during deep drawing and the ear is at its highest position. In Fig. 7.57

on p. 394, the directions are at about ±45_ on the photograph.

### Explain why attenuation is not a big problem in PET.

Consider a 2-D object consisting of two triangle compartments, as shown in Figure P9.4. Suppose a solution containing a 511 KeV gamma ray emitting radionuclide with concentration f = 0.5….

### Give the mean and the variance of the reconstructed image, mean[ˆ f(x, y)] and var[ˆ f(x, y)].

Ignoring the inverse square law and attenuation, an approximate reconstruction for SPECT imaging is given by where c˜() =  {||W()} and W() is a rectangular windowing filter that cuts off at = 0…..

### Find the numerical responses in each to an event in crystal C(4, 6).

Suppose a PET detector comprises four square PMTs (arranged as a 2 by 2 matrix) and a single BGO crystal with slits made in such a way that it is….