A string pulling head structure of a racket stringer, including a first string chuck and a second string chuck fixed with each other and a first chucking plate and a second chucking plate disposed between the first and second string chucks. The mounting device includes a first pin having a first head and a second pin having a second head, wherein the second head projects radially beyond the second pin only on one side of the second pin. It also forms a vertical structure where the P and N ends are on the top and bottom sides of the LEDs, respectively. A system for simulating and solving a partial differential equation comprising a quantum computer and a classical processor. Embodiments of these methods further comprise subjecting the predetermined Ti 6-2-4-2 alloy to a pre-forming annealing cycle comprising: heating the predetermined alloy to a pre-forming annealing temperature of about 1550-1750\xb0 F. A voltage source layer and a ground layer of the printed circuit board are divided into an analog area and a digital area respectively via an isolation line, and adapted to conduct voltage source signal and ground signal respectively.