If G is an abelian group of order u, and D is a subset of G with k elements such that every nonidentity element can be expressed 2 times in the form a b, where a and b are elements of D, then D is called a (u, k, A) difference set in G. The order n of the difference set is k 1. In this paper we consider the parameter values v = 22di 2, k = 22d+ ’ 24 ,I= 22d 2d, and n=22d. The rank r of G is the...

Control of hot metal rolling process plays an important role in assuring high product quality and safe process operation. Although there have been many looper control technologies recently developed for finishing rolling processes, looperless interstand tension control of roughing and intermediate rolling mills remains a hard-to-solve problem. This paper proposes a current comparison based inte...

The purpose of the hot rolling mill is to make a preheated steel block thinner and longer, see Figure 1. This is done by pulling the plate through two parallel rolls mounted in the rolling mill. Due to the large forces obtained in hot rolling, the elastic de ection of the rolling mill is of the same order of magnitude as the plate thickness. Variations in the rolling force caused by variations ...

Background One or two decades ago, when computers resources were much lower, steady-state formulations have attracted considerable interest in the field of material forming simulation More precisely in the metal forming field, it was extensively applied for rolling processes. Early simulations were done for thick plates [1] and simple shape rolling [2]. They were extended to seamless tube rolli...

Purpose: In the present work, different combinations of fits and accuracies, in relation to profiles mating parts, have been analysed order assess degree engagement transmissions that contain intermediate rolling elements. The aim this work is determine which decreased accuracy, but nevertheless provide a minimum manufacturing clearance for transmission reduce cost parts production. Methods mat...

Materials with ultrafine-grained structure and unique physical and mechanical properties can be obtained by methods of severe plastic deformation, which include processes of asymmetric rolling (AR). Asymmetric rolling is a very effective way to create ultrafine-grained structures of metals and alloys. Since the asymmetric rolling is a continuous process, it has great potential for industrial pr...

In this paper, a mathematical model for symmetrical multi-layer sheet rolling, in which the layers are unbounded before rolling, by using the upper bound method and stream function theorem is proposed. Using this model, we can investigate the plastic deformation behavior of sheets at the roll gap during rolling. Effect of various rolling conditions such as initial and final thickness and flow s...

Endothelial surface expression of P-selectin and subsequent leukocyte rolling in venules can be induced by mast cell-derived histamine and binding of thrombin to protease-activated receptor-1 (PAR1). We hypothesized that activation of endothelial PAR2 by mast cell tryptase or other proteases also contributes to inflammatory responses. Leukocyte rolling flux and rolling velocity were assessed by...

Abstract Wood under thermo-mechanical densification behaves differently depending on the cross-sectional growth ring orientation (GRO) relative to direction of compression. This influences degree cell damage, but also shape-memory effects occurring when compression load is released (spring-back) and timber re-moistened (set-recovery). To study how GRO effects, Scots pine specimens were separate...