Oanh Chau

University of La Réunion · Department of Mathematics

In this paper, we study a class of dynamic thermal problems involving a frictional normal compliance adhesive contact model and a non-clamped condition for visco-elastic materials. The variational formulation of the problem leads to a general system defined by a second-order quasi-variational evolution inequality on the displacement field coupled w...

We study a class of dynamic sub-differential contact problems with friction, and thermale ects, for time depending long memory visco-elastic materials, with or without the clamped condition.We describe the mechanical problem, derive its variational formulation, and after specifyingthe assumptions on the data and operators, we prove an existence and...

In this paper, we study a class of dynamic thermal problems involving a frictional normal compliance adhesive contact model and a nonclamped condition for viscoelastic materials. The variational formulation of the problem leads to a general system defined by a second-order quasi-variational evolution inequality on the displacement field coupled wit...

A duality approximation method combined with an adaptive finite element method is applied to solve a free boundary problem with periodic boundary conditions in lubrication theory.

We study a class of dynamic thermal sub-differential contact problems with friction, for long memory viscoelastic materials, without the clamped condition, which can be put into a general model of system defined by a second order evolution inequality, coupled with a first order evolution equation. After statement of an existence and uniqueness resu...

A mathematical problem modeling dynamical behavior of viscoelastic materials is studied. The problem is related to highly nonlinear and non-smooth phenomena like contact, friction and a class of dynamic contact problems with friction and thermal effects. The applied approach leads to a system involving variational inequalities and a fully discrete...

In this paper, we present a synthesis of different results obtained recently in the papers (Chau and Awbi, Appl Anal 83:635–648, 2004; Addi et al. Discret Contin Dyn Syst 31:1039–1051, 2011; Adly et al. Numer Algebra Control Optim 2:89–101, 2012; Adly and chau, to appear in Mathematical Programming; Chau et al., Int J Appl Math Mech, 2012). It conc...

In this paper, we present a synthesis of different results obtained recently in the papers (Chau and Awbi, Appl. Anal. 83(6):635-648, 2004; Addi et al., Discrete Continuous Dyn. Syst. 31(4):1039-1051, 2011; Adly et al., Numer. Algebra Control Optim. 2(1):89-101, 2012; Adly and Chau, Math. Program. Ser. B, 2014; Chau et al., Int. J. Appl. Math. Mech...

In this chapter we study a dynamic frictional contact problem with normal compliance and non-clamped contact conditions, for thermo-viscoelastic materials. The weak formulation of the problem leads to a general system defined by a second order quasivariational evolution inequality coupled with a first order evolution equation. We state and prove an...

We study a class of dynamic thermal sub-differential contact problems with friction, for long memory visco-elastic materials, without the clamped condition, which can be put into a general model of system defined by a second order evolution inequality, coupled with a first order evolution equation. We present and establish an existence and uniquene...

We study a class of dynamic thermal sub-differential contact problems with friction, for time-depending long memory viscoelastic materials, with or without the clamped condition, which can be put into a general model of system defined by a second order evolution inequality, coupled with a first order evolution equation. We present and establish an...

We study a class of dynamic thermal sub-differential contact problems with friction, for long memory visco-elastic materials, which can be put into a general model of system defined by a second order evolution inequality, coupled with a first order evolution equation. We present and establish an existence and uniqueness result, by using general res...

We study the evolution of a class of quasistatic problems, which describe frictional contact between a body and a foundation. The constitutive law of the materials is elastic, or visco-elastic: with short or long memory, and the contact is modelled by a general subdifferential condition on the velocity. We derive weak formulations for the models an...

Three patients with total membranous stricture after mechanical anastomosis in high anterior resection, are presented. In the first of them the treatment was surgical: longitudinal enterotomy with transversal closure. In the other two the problem was resolved by means of endoscopic procedures with radioscopie assistance. Most of the total membranou...

Background: Frequency of evisceration remained constant in the last 50 years. It is a serious postoperative complication with high morbidity, cost and with important mortality. Objective: To report of a General Surgery Service experience in a private hospital and show the outcomes obtained Setting: Service of Surgery, Clínica Güemes, Luján (B.A.),...

We study a general system defined by a second order evolution equation, coupled with a first order differential equation, which can model some classes of dynamic thermal contact problems. We present and establish an existence and uniqueness result, by using general results on evolution equations and Banach's contraction principle, with monotone ope...

In this paper, we develop a mathematical approach which can be used to display, in a systematic, rigorous and efficient way, various qualitative properties of a large class of dynamical and quasi-steady biochemical models. The applicability of the methodology has been examined for various biochemical reactions, enzyme kinetics and multi enzyme syst...

We are interested in the dynamic evolution of a thermoviscoelastic body in frictional contact with a rigid foundation. The contact is modeled by a general normal damped response with friction law and heat exchange. We establish the existence and uniqueness of weak solution, under the condition that the viscosity is sufficiently strong. Finally, the...

In this paper, we are interested in the dynamic evolution of an elastic body, acted by resistance forces depending also on the displacements. We put the mechanical problem into an abstract functional framework, involving a second order nonlinear evolution equation with initial conditions. After specifying convenient hypotheses on the data, we prove...

Background: The diagnosis and treatment of the abdominal abscess are difficult. The morbimortality is high because of the late diagnosis, localization failure and access difficulties. Objective: to specify the percutaneous guided drainage indications in the abdominal abscess treatment, to describe the technique and to analyze the results. Setting:...

Title: Percutaneous treatment for iliac occlusion. Objective: To prove the usefulness of the Nitinol vascular endoprosthesis in the iliac lesion treatment. Material and methods: Since May 1996, to December 2005, 26 iliac arteries in 21 male patients were treated. The medium age was 56 years. 23 were stenotic lesions and 3 were obstructive lesions....

Lithiasis of the biliary duct is usually solved successfully by sphinterectomy and endoscopic removal of the gallstones. However, there are some cases of complex Lithiasis that, due to the big size of the litho or the anatomic changes of the biliary duct, hinder the removal process. These cases can be successfully treated with trasendoscopic lithot...

Most of the prospective studies proved the clear superiority of the prosthetic mesh reparation over the anatomic procedures in the surgical treatment of incisional hernias, and supported the mesh technique yet in the small defects.In this paper it is presented the technique of mesh reparation of the most frequent incisional hernias.

We analyze a problem which describes the frictional contact between a thermoviscoelastic body and a rigid foundation. The process is assumed to be quasistatic and the contact is modeled by a general normal damped response condition with friction law and heat exchange. Then we present a variational formulation of the problem, which is set in an abst...

A model for the dynamic, adhesive, frictionless contact between a viscoelastic body and a deformable foundation is described. The adhesion process is modeled by a bonding field on the contact surface. The contact is described by a modified normal compliance condition. The tangential shear due to the bonding field is included. The problem is formula...

A model for the adhesive, quasistatic and frictionless contact between a viscoelastic body and a deformable foundation is described. The adhesion process is modelled by a bonding field on the contact surface, and contact is described by a modified normal compliance condition. The problem is formulated as a coupled system of a variational equality f...

We study a dynamic frictionless contact problem between a viscoelastic body and an obstacle, the so-called foundation. The contact is subjected to an adhesion effect, whose evolution is described by an ordinary differential equation. For the variational formulation of the contact problem, we present and prove an existence and uniqueness result. A f...

This work deals with the approximation of the contact problem for a viscoplastic material with the Signorini contact conditions by the problem with normal compliance, when the surface deformability coefficient converges to zero, i.e., when the surface stiffness tends to infinity, which represents a perfectly rigid obstacle. The possible damage of t...

We study a quasistatic frictionless viscoplastic contact problem with normal compliance and damage for elastic-visco-plastic bodies. The mechanical damage of the material, caused by excessive stress or strain, is described by a damage function whose evolution is modelled by a parabolic inclusion. We provide a variational formulation for the mechani...

We study a quasistatic frictionless contact problem with normal compliance and damage for elastic–viscoplastic bodies. The mechanical damage of the material, caused by excessive stress or strain, is described by a damage function whose evolution is modelled by an inclusion of parabolic type. We provide a variational formulation for the mechanical p...

We consider two quasistatic problems which describe the frictional contact between a deformable body and an obstacle, the so-called foundation. In the first problem the body is assumed to have a viscoelastic behavior, while in the other it is assumed to be elastic. The frictional contact is modeled by a general velocity dependent dissipation functi...

We consider a mathematical model which describes the frictional contact between a viscoelastic body and a reactive foundation. The process is assumed to be dynamic and the contact is modeled with a general normal damped response condition and a local friction law. We present a variational formulation of the problem and prove the existence and uniqu...

We consider dynamic problems which describe frictional contact between a body and a foundation. The constitutive law is viscoelastic or elastic and the frictional contact is modelled by a general subdifferential condition on the velocity, including the normal damped responses. We derive weak formulations for the models and prove existence and uniqu...

We consider a mathematical model which describes the bilateral frictional contact between a nonlinearly viscoelastic body and a rigid foundation. We present two alternative yet equivalent weak formulations of the problem, and establish existence and uniqueness results when the friction coefficient is small. The proofs are based on classical results...

We consider a mathematical model for quasistatic bilateral contact of a viscoelastic body with a rigid foundation. The contact is modeled with Tresca’s friction law with friction bound depending on the total slip. We present the classical as well as variational formulations of the problem, and establish the existence and uniqueness of weak solution...

The present paper is devoted to the study of a new class of quasivariational inequalities in a real Hilbert space. We indicate sufficient conditions in order to establish the existence, the uniqueness and the Lipschitz continuous dependence of the solution with respect to the data. The proofs are based on arguments of topological degree and fixed p...

We consider an initial and boundary value problem which describes the evolution of a viscoelastic body submitted to body forces and surface tractions. The viscoelastic constitutive law is assumed to be nonlinear and the process is quasistatic. We prove the existence and the uniqueness of the solution using arguments of monotone operators theory and...

A 35 year old woman, cocaine addict, suffered Candida albicans aortic valve endocarditis complicated with embolisation of infected vegetations in the distal abdominal aorta. She underwent successful staged aortic valve replacement followed by transaortic and transfemoral thrombectomy. One month later an arteriogram disclosed partial occlusion of th...

We consider a mathematical model which describes the quasistatic evolution of a viscoelastic body in frictional contact with a rigid foundation. The contact is bilateral and the friction is modeled with a general nonlocal friction law. We present the classical as well as a variational formulation of the problem and establish the existence and uniqu...

The different breast biopsy procedures have their indications, advantages and disadvantages. They are more complementary than competitive. It is cause of controversy the type of biopsy election and the use of frozen section and immediate or postponed treatment. The objective of this paper is to specify the more convenient breast biopsy type in each...

We evaluated the utility of the Chinese version of the Edinburgh Postnatal Depression Scale (EPDS) and measured the prevalence of major depression six weeks after confinement among Chinese women in Hong Kong. A prospective cohort of 145 women completed the EPDS, the 12-item General Health Questionnaire (GHQ) and the Beck Depression Inventory (BDI)...

Two cases of divided choledochus are presented. One of them was bifurcated and the other trifurcated. The division of the terminal part of the principal biliary duct is exceptional, specially the trifurcation. We think that our observation of trifurcated choledochus respond to a tardy subdivision of the biliary duct and that of the three ducts, the...

Background: The use of mesh in the surgical reparation of medial incisional hernias is controversial. Objective: To specify the indications of the mesh repair of the incisional hernias. To describe Technical aspects of the mesh reparation. Setting: Service of Surgery, Clínica Güemes, Luján (B.A.), Argentina and Meeking County Memorial Hospital, Lit...

Proximate composition and metabolizable energy of raw and processed foods derived from cereals and legumes, were determined. Results can be used to revise the out of day national composition table, to incorporate data of ash, new data of dietary fiber obtained by an enzimatic hydrolysis method, asimilable carbohydrates and metabolizable energy. The...

In this paper we are interested in the approximation of the Sig-norini's contact problem by the normal compliance with damage. Precisely we study the convergence of the solution of the normal compliance contact problem in viscoplasticity to the solution of the Signorini's contact problem. After summarizing recent results about the variational formu...

We consider a mathematical model which describes the bilateral dynamic contact of a viscoelas-tic body with a rigid foundation. The constitutive law is supposed to be viscoelastic with long memory, and the contact is frictional obeying the Tresca's friction law. We present the clas-sical formulation of the problem, and derive a variational formulat...