The contact dynamics method (CD) is an efficient simulation technique of dense granular media where unilateral and frictional contact problems for a large number of rigid bodies have to be solved. In this paper we present a modified version of the contact dynamics to generate homogeneous random packings of rigid grains. CD is coupled to an external pressure bath, which allows the variation of t...

This paper is concerned with the frictionless unilateral contact problem (i.e., a Signorini problem with the elasticity operator). We consider a mixed finite element method in which the unknowns are the displacement field and the contact pressure. The particularity of the method is that it furnishes a normal displacement field and a contact pressure satisfying the sign conditions of the continu...

The paper deals with a phase field model for formulation and solution of the topology optimization problems of bodies in unilateral contact consisting in the normal contact stress minimization. The cost functional includes also surface and bulk energy terms. These terms allow to control global perimeter constraint and the occurence of the intermediate solution values. The optimal topology is ob...

background: free-living amoeba (fla)-related keratitis is a progressive infection of the cornea with poor prognosis. the present study aimed to investigates the con­tact lenses of patients with keratitis for pathogenic free-living amoebae. methods: overall, 62 contact lenses and their paraphernalia of patients with kerati­tis cultured and tested for the presence of free-living amoebae using mor...

AIMS To report the clinical findings and visual outcome of patients with extended wear contact lens (EWCL) related bacterial keratitis. METHODS 11 cases with EWCL related bacterial keratitis were included. Corneal scrapings were obtained for cytology and cultures. RESULTS Nine patients had unilateral bacterial keratitis and two patients showed bilateral involvement. Corneal scrapings reveal...

This paper considers the effect of unilateral nonlinearities on the stability of discrete time control systems, a problem of some importance in haptic display. The unilateral nonlinearity is a simple piecewise linear function: ξ(x) = x for x≥0, ξ(x) = 0 for x<0. This function plays an important role in the modeling of collisions, and is a part of essentially all implementations of virtual surfa...

PURPOSE To report a case of unilateral total limbal stem cell (LSC) failure and corneal opacification secondary to thimerosal- and contact lens-induced ocular surface toxicity. METHODS Interventional case report and review of the literature on thimerosal-induced ocular surface changes. RESULTS A 49-year-old woman with a 2-year history of long-term soft contact lens wear developed unilateral...

Applying high order finite elements to unilateral contact variational inequalities may provide more accurate computed solutions, compared with linear finite elements. Up to now, there was no significant progress in the mathematical study of their performances. The main question is involved with the modeling of the nonpenetration Signorini condition on the discrete solution along the contact reg...

The analysis of unilateral sliding contact in elasticity is equivalent to a minimisation problem subjected to a set of inequality constraints. However, the presence of boundary discontinuities, such as those stemming from the spatial discretisation, appears as a major problem to determine the set of active constraints. This work introduces a smoothing technique of the master surface resorting t...

Cervical facet fractures and dislocations represent approximately 6% of all cervical spine fractures.1 The clinical spectrum of these injuries ranges from patient being neurologically intact to complete neurological deficits. They can be unilateral or bilateral and may be associated with subluxation or dislocations. The unilateral facet dislocations are produced because of flexion, hyperextensi...