Nicolae Pop

Nicolae Pop
Institutul de Mecanica Solidelor | imsar

Professor

About

52
Publications
9,794
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278
Citations

Publications

Publications (52)
Article
Full-text available
In this paper, we discuss the question of finding an optimal control for the solutions of the problem with dry friction quasistatic contact, in the case that the friction law is modeled by a nonlocal version of Coulomb’s law. In order to get the necessary optimality conditions, we use some regularization techniques, and this leads us to a problem o...
Article
Full-text available
p>The firefighting robot control using intelligent Extenics control interfaces ICEx developed by versatile, intelligent and portable robot VIPRO platform is presented. Subsequently, VIPRO platform architecture, the innovative versatile, intelligent, portable platform, is applied on firefighting robots VIP- FiR&FiTRo, Extenics intelligent control an...
Article
Full-text available
The main concern of this study is an extension of some results, proposed by Green and Lindsay in the classical theory of elasticity, in order to cover the theory of thermoelasticity for dipolar bodies. For dynamical mixed problem we prove a reciprocal theorem, in the general case of an anisotropic thermoelastic body. Furthermore, in this general co...
Article
The Industry 4.0 and smart city solutions are impossible to be implemented without using IoT devices. There can be several problems in acquiring data from these IoT devices, problems that can lead to missing values. Without a complete set of data, the automation of processes is not possible or is not satisfying enough. The aim of this paper is to i...
Chapter
This paper deals with boundary optimal control problem of a frictional quasi-static contact problem with dry friction, described by a nonlocal version of Coulomb’s law. We prove the existence of a boundary optimal control for the regularized problem obtained from a quasi-static contact problem with dry friction. For getting the necessary optimality...
Article
Full-text available
The principal objective of our study is to emphasize the strategies for the walking robot mathematical model to traverse an uneven terrain, respecting the hypothesis of environment model defined by us. The multiple aspects on axiomatic systems, with possible application to environment's mathematical model axiomatization, open an interesting new way...
Article
Full-text available
The goal of this article is trajectory generation for biped robots based on Model Predictive Control (MPC) and the receding-horizon principle. Specifically, we want to minimize the error between the desired CoM and ZMP trajectory and the actual one and the cancellation of the shock gradient of the CoM and ZMP movements. Model predictive control (MP...
Article
Full-text available
In this article we continue the study started in [8] to use Riesz MValgebras for IoT devices signals processing. The Shepard local approximation operators introduced in [8] were defines such that to approximate single variable functions. In real industrial usage, the signals coming from IoT devices may be influenced by mode than a parameter, and th...
Chapter
This chapter contains sections titled: Introduction The Choice of the Model Mathematical Modeling of Two‐Link Biped Walking Robot Linear Control Design Results and Discussion Conclusions Acknowledgment
Chapter
This chapter contains sections titled: Introduction On the Environment's Mathematical Model Physical and Mathematical Models of the Walking Robot Leg On Critical Positions of 3D Walking Robots Mathematical Model of Beam Without Damping Mathematical Model of Beam with Viscous Damping Conclusion Acknowledgment
Article
Full-text available
The exposure is dedicated in the first to mathematical modeling of the environment where the aspects on the walking robots evolution models are described. The environment's mathematical model is defined through the models of kinematics or dynamic systems in the general case of systems that depend on parameters. The important property of the dynamic...
Article
Full-text available
Recovering and maintaining the balance of the biped walking robots play an important role in their operation. In this article we will analyze some strategies for balancing in the sagittal plane, in the presence of external disturbances and changing the proportions between leg's length and trunk's length (golden section), and/or adding weights (boot...
Article
Full-text available
The paper is based on the analytical and experimental results from [14], [15] and reveals, by mathematical methods, the degradation of ma- terial stifiness due to the decrease of the first natural frequency, when the driving frequency is slightly lower than the first natural frequency of the undegradated structure. By considering the vibration of t...
Article
Full-text available
This article presents a novel rescue robot with three-degrees of freedom leg mechanism based on the serial–parallel and wheel-legged mechanisms, which consists of two Universal joint-Prismatic joint-Spherical joint plus one Universal joint and Revolute joint serial–parallel mechanism. Firstly, the structure model of the whole mechanism and the leg...
Article
Full-text available
This paper presents a model of approaching the managing the innovation process in case of small and medium-sized companies. The process of development by means of innovation is analysed from two perspectives, namely: from the perspective of companies that apply the innovations and from the perspective of universities as suppliers of technologies an...
Conference Paper
Full-text available
According to the dynamical systems theory, many dynamical systems (physical-mechanic, chemical, socio-economical, ecological) can be modeled by mathematical relations, such as deterministic and/or stochastic differential and/or difference equations. These systems change with time or any other independent variable or parameters (friction in this cas...
Article
This paper is dedicated to some results in the thermodynamic theory of porous elastic bodies. Unlike other studies, here is included the voidage time derivative among the independent constitutive variables. In order to analyse the spatial behavior of solutions, we use some estimates of Saint-Venant type in the case of bounded bodies, while for the...
Article
We study infinitely differentiable functions which are representable into a Newton interpolating series at a suitable interpolation sequence with terms in [0, 1]. Applications of this series to approximate the solution of boundary value problems for linear systems of differential equations are presented.
Article
Full-text available
Statistical methods were applied to the assessment of the multi-elements pollution degree of the soil with heavy metals and arsenic (microelements) in Baia Mare area, NW Romania. The content of several microelements were analyzed in soil samples from four zones in the studied area. Pollution indices were used to define the pollution degree compared...
Article
This paper presents a robot real time control method and system in order to restore the hexapod robot equilibrium position. Traditional methods for this problem generally define a line between the area where the robot is in stable equilibrium and the area where the robot loses its equilibrium. As opposed to traditional methods, in this research, ex...
Article
The present study demonstrates the use of optimization technology in improving the bolted joint design. Design exploration from ANSYS Workbench is used in the study. The objective of the study was to minimize the bolted joint deformation in order to optimize the joint. Variations of the parameters such as bolt pretension force, friction coefficient...
Article
Full-text available
A real Banach algebra of Newton interpolating series, used to approximate the solutions of multipoint boundary value problems for ODE's, is studied.
Article
The dynamic contact problem in linear viscoelasticity will be discretized with inite element method and finite difference method. The concept of the a priori stability estimation for dynamic frictional contact will be analyzed by using the local split of the Coulomb model. The split will be implemented such that the global balance of energy will be...
Article
Newton interpolating series constructed by means of Newton interpolating polynomials are used to obtain approximate solutions of boundary value problems for linear differential equations.
Article
The paper deals with the study of approximate solutions, which are entire functions, of multipoint boundary value problems for differential equations. The solutions are represented as Newton interpolating series.
Article
Full-text available
The quasi-static model of contact problem with friction is a dynamic contact problem without inertial effects and we propose that it may be solved by solving a sequence of static contact incremental problems corresponding to a sequence of loads. This discrete quasi-static model is obtained from the approximation with finite difference of the tempor...
Article
Full-text available
Approximate solutions of multipoint boundary value problems for linear differential equations are studied. The approximate solution is a partial sum into a series constructed by means of Newton interpolating polynomials that verifies the boundary conditions. This idea was used in number theory to prove the transcendence of some numbers.
Article
Full-text available
The quasistatic contact problem with dry friction, contributes to the achievement of a numerical model for the simultaneity of different kinds of viscoplastic, incompressible materialsforming. Starting from a variational formulation of the problem, which extends the static case, a perturbed Lagrangean, discrete formulation within the framework of f...
Article
Full-text available
The aim of this paper is to give an algorithm for nonsmooth minimization using the generalized Jacobians with applications in contact problems. Some definitions, results and algorithms from non-smooth analysis are presented which lead to some sufficient conditions such that the nonlinear and nondifferentiable system obtained in modeling the contact...
Article
The paper is concerned with the numerical solution of the quasi-variational inequality modelling a contact problem with Coulomb friction. After discretization of the problem by mixed finite elements and with Lagrangian formulation of the problem by choosing appropriate multipliers, the duality approach is improved by splitting the normal and tangen...
Article
This paper presents some results from nonsmooth analysis which leads to sufficient conditions such that the nonlinear and nondifferential system that modeling the contact problems with frictions, does have one solution, obtained by Newton's method using the generalized gradient.The generalizations by means of Newton's method can be applied to solve...
Conference Paper
Full-text available
The paper is concerned with the numerical solution of the quasi-variational inequality modelling a contact problem with Coulomb friction. After discretization of the problem by mixed finite elements and with Lagrangian formulation of the problem by choosing appropriate multipliers, the duality approach is improved by splitting the normal and tangen...
Article
Approximate solutions of two point boundary value problems for linear differential equations are studied. An approximative solution is a partial sum of a series constructed by means of Newton interpolating polynomials which verify the boundary conditions.
Article
Full-text available
The aim of the paper is to prove the convergence of a Uzawa type algorithm for a dual mixed variational formulation of a quasi-static contact problem with friction. This problem is considered as a saddle point problem which is approximated with the mixed finite element, where the stress, displacement and tangential displacement on the contact bound...
Article
Full-text available
The contact conditions and stability conditions, which include an inf-sup condition for mixed finite element method for contact problems with friction, are translated on the Lagrange multiplier space and on the space of trace functions called the mortar space.
Article
The aim of this paper is to discuss two generalizations of a result due to J. S. Pang [Math. Oper. Res. 15, No. 2, 311-341 (1990; Zbl 0716.90090)], for solving B-differentiable equations with Newton’s method and some results of F. H. Clarke [“Optimization and nonsmooth analysis.” (1983; Zbl 0582.49001)] for solving nondifferentiable equations using...
Article
In this paper we consider the so-called “inexact” Uzawa algorithm for solving saddle point systems which arise in the discretization of contact problems. By using appropriate Lagrangeans, one can transform the original problem (the contact problem) into a saddle point problem on a convex set. The inexact Uzawa methods replace the exact inverse of a...
Article
In this article to demonstrate the existence of the solution of the equation modelling the static problem of elastic contact using the Brezis' fundamental theorem of pseudo-monotonous operators [4]. The existence of a solution of the equation modelling the dynamic contact problem with Coulomb friction, is proved for a particular case, when the mate...
Article
The present paper is a continuation of the analysis presented by the author and M. Com (1991), which consists in a numerical analysis of a quasistatic contact problem in linear elasticity with dry friction. The problem is intended to model the physical situation of two elastically deforming bodies that come into contact with friction obeying the no...
Article
The present paper is concerned with the analysis with finite element of a friction contact phenomenon for two elastic bodies that come into contact with friction obeying the normal compliance law. Variational principles for a class of friction contact problems are also established and finite element models and numerical algorithms for analyzing of...
Article
The paper is concerned with the numerical analysis of a quasistatic contact problem in linear elasticity with dry friction. The problem is intended to model the physical situation of two elastically deforming bodies that come into contact with friction obeying the normal compliance law. Lagrange incremental multipliers method and penalty function a...
Article
The existence of solution of a dynamic contact problem is proved in a particular case when the material is viscoelastic with short memory and when the bilinear form includes the displacement velocity with Coulomb friction. The proof is based on penalization and regularization methods.

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Project (1)
Project
SMOOTH - Smart Robots for Firefighting