A post-trade aggregation system includes an allocation middleware interface, which interacts with an order management system to allocate and settle trades. An annular groove is formed at the circumferential edge of the top face of a piston crown, or at the top of the exterior circumferential face of the crown, and an annular protruding strip is formed as a continuation of an edge of the opening of the annular groove. The binder comprises at least about 20% by volume of the gas generating material. The tube receiving portion is formed with an arcuate shape which corresponds with the shape of the tube member to be inserted therein. The best metric for the predecessor state is determined using a survivor vector stored in memory.