Many systems can be modeled with hard and various size spheres, therefore packing and geometrical structures of such sets are of great importance. In this paper, rigid spherical particles distributed in different sizes are randomly packed in confined spaces, using a parallel algorithm. Mersenne Twister algorithm was used to generate pseudorandom numbers for initial coordination of particles. Di...

We present a new lemma stating that, given an arbitrary packing of a set of rectangles into a larger rectangle, a “structured” packing of nearly the same set of rectangles exists. This lemma has several implications on the approximability of 2-dimensional packing problems. In this paper, we use it to show the existence of a polynomial-time approximation scheme for 2-dimensional geometric knapsa...

The liquid axial dispersion inside modern structured packings (Sulzer Mellapak™ 500.Y, Raschig Super-Pak 350Y) and one random packing of the 4th generation (Raschig Super-Ring 0.3) was measured by means computed tomography. As gas velocity is known to have little effect on at low hydraulic load, all experiments were conducted without countercurrent flow loads B = 10, 15, 20 m3m−2h−1 in a column...

objective: to evaluate the efficacy of modified perihepatic packing (mphp) in reducing the rate of re-bleeding rate after packing removal. methods: this was an experimental study being performed in shiraz animal laboratory. high grade liver parenchymal injury was induced in 30 transgenic australian rabbits which were then divided into two groups. group a (control) included 14 and group b (exper...

We show how to approximate the feasible region of structured convex optimization problems by a family of convex sets with explicitly given and efficient (if the accuracy of the approximation is moderate) self-concordant barriers. This approach extends the reach of the modern theory of interior-point methods, and lays the foundation for new ways to treat structured convex optimization problems w...

the main issues in nasal surgery are to stabilize the nose in the good position after surgery and preserve the cartilages and bones in the favorable situation and reduce the risk of deviation recurrence. also it is necessary to avoid the synechia formation, nasal valve narrowing, hematoma and bleeding. due to the above mentioned problems and in order to solve and minimize them nasal packing, na...

In a graph G = (V,E), a subset $S⊂V$ is said to be an open packing set if no two vertices of S have a common neighbour in G. The maximum cardinality of an open packing set is called the open packing number and is denoted by $ρ^{o}$. This paper further studies on this parameter by obtaining some new bounds.