# Jakub Krzysztof GrabskiPoznan University of Technology · Institute of Applied Mechanics

Jakub Krzysztof Grabski

PhD Eng

## About

55

Publications

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389

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Introduction

Additional affiliations

October 2012 - present

October 2012 - present

Education

March 2010 - September 2011

October 2009 - February 2013

October 2006 - February 2010

## Publications

Publications (55)

In this paper, the space-time generalized finite difference scheme is proposed to effectively solve the unsteady double-diffusive natural convection problem in the fluid-saturated porous media. In such a case, it is mathematically described by nonlinear time-dependent partial differential equations based on Darcy's law. In this work, the space-time...

One of the challenges in research by modern engineers is the acquisition of new materials for the creation of various constructions in order to improve their properties, including mechanical ones. One possible way to achieve this goal is through composite materials. Moreover, the use of such materials in various real constructions leads to material...

Dear Colleagues, Corrugated materials are increasingly used as construction materials or load-bearing elements in various engineering applications. Due to the specific compositions of corrugated materials, the ratios of their load capacities to the section weights are much higher than for traditional solid sections. Composite materials, due to thei...

In the current research, a torsion of isotropic prismatic rods with elastic–plastic behavior under non-linear hardening behavior, such as Swift, Voce, and Ramberg–Osgood relations, is investigated with the method of fundamental solutions. Based on the Saint–Venant displacement assumption and deformation theory of plasticity for the stress–strain re...

In this study, a novel meshless stable numerical solver is proposed to solve the non-conservative form of shallow water equations. Since they form a hyperbolic system of equations, discontinuous solutions are allowed to transmit during the simulation. The generalized finite difference-split coefficient matrix method, recently proposed, is applied a...

In the paper, we consider a numerical simulation of torsional experiment and identification of elastoplastic properties of materials in such a test. The former is a direct problem. We consider a nonlinear boundary value problem, which is solved by means of the method of fundamental solutions and global radial basis function collocation method. The...

This article focuses on the derivation of simplified predictive models for the identification of the overall compressive stiffness and strength of corrugated cardboards. As a representative example an unsymmetrical 5-ply sample (with E and B flute) was used in this study. In order to exclude unreliable displacement measurement in the standard edge...

The article focuses on derivation of simplified predictive models for identification of overall compressive stiffness and strength of corrugated cardboards. As a representative example an unsymmetrical 5-ply sample (with E and B flute) was used in this study. In order to exclude unreliable displacement measurement in the standard edge crush test, t...

This Special Issue of Materials is devoted to the mechanics of corrugated and composite materials. Corrugated materials are increasingly used as construction materials or load-bearing elements in various engineering applications. Due to the specific compositions of corrugated materials, the ratios of their load capacities to the section weights are...

This paper presents a modified analytical formula for estimating the static top-to-bottom compressive strength of corrugated board packaging with different perforations. The analytical framework is based here on Heimerl’s assumption with an extension from a single panel to a full box, enhanced with a numerically calculated critical load. In the pro...

This paper presents mixed analytical/numerical method for estimating the static top-to-bottom compressive strength of corrugated packaging with different ventilation openings and holes, in which the torsional and shear stiffness of corrugated cardboard as well as the panel depth-to-width ratio are included. Analytical framework bases on Heimerls as...

In the present work, an analytical equation describing the plate torsion test taking into account the transverse shear stiffness in sandwich plates is derived and numerically validated. Transverse shear becomes an important component if the analyzed plate or shell is thick with respect to the in-plane dimensions and/or its core has significantly lo...

This paper presents analytical methods for estimating the static top-to-bottom compressive strength of simple corrugated packaging, in which the torsional and shear stiffness of corrugated cardboard as well as the panel depth-to-width ratio are included. The methods are compared herein with a basic and more detailed buckling description with the su...

The paper presents the application of the BTS motion capture system to verify the FMS test assessment. The research group consisted of adolescent female football players who underwent standard FMS assessment by a physiotherapist. In order to objectify the physical performance assessment, a mechanical model was proposed, on the basis of which the pa...

In a description of materials for orthotropic panels with a soft and/or corrugated core, it is important to correctly determine all constitutive parameters. In laboratory practice, the determination of transverse shear modulus is often overlooked. This paper presents a method for determining this property based on a plate torsion test and a correct...

Application of the method of fundamental solutions in combination with the global radial basis function collocation method for analysis of fluid flow and heat transfer in an internally finned square duct is presented in the paper. Fluid flow problem is solved using the modified method of fundamental solutions. After that, the average fluid velocity...

In this paper, non-Newtonian fluid flow and heat transfer in an internally finned duct is considered. The problems are governed by nonlinear equations with linear boundary conditions. In this paper, the solution is obtained with two Picard iteration processes, separately for the fluid flow and heat transfer problems. Furthermore, in both problems t...

Screening blood tests for thyrometabolic status determination are difficult in interpretation because of many factors like age, sex or measurement method that influence their proper interpretation. To solve this problem machine learning techniques, like artificial neural networks (ANN) can be applied, but their application is very common belittled...

A simple and common method for assessing the jumping ability is determination of the jump height during the vertical countermovement jump. However there are different techniques of measurements in biomechanics, e.g. using force plates or accelerometers. In this study the center of jumper’s body is determined based on the motion capture system measu...

Sleep Apnea Syndrome (SAS) becomes an important medical and social problem of contemporary societies. It is burdensome, it can be dangerous to health and even cause of death. The most efficient way to detect this syndrome is polysomnography. It gives good results but it is expensive and not commonly available. Main aim of this study is to present a...

In the method of fundamental solutions (MFS), the solution of a boundary value problem (BVP) is approximated by a linear combination of fundamental solutions expressed in terms of sources which are located on a pseudo-boundary outside the domain of the problem. A major issue in such applications is the optimal placement of these sources. In this wo...

The method of fundamental solutions is a more and more popular meshless method for solving boundary or initial–boundary value problems. The most important issue in this method is the determination of the positions of the source points. The accuracy of the method depends strongly on the distribution of the source points. In this paper placement of t...

In the paper, a numerical simulation of the Beavers-Joseph experiment is presented. The simulation is based on a meshless method which is called the Trefftz method with the special purpose Trefftz functions. The porous medium is modeled as a regular array of fibers. Three kinds of arrays are taken under consideration: triangular, square, and hexago...

The aim of this study was to check the possibility of identifying the persons based on the properties of thermal maps and a temperature distribution of a hand, obtained from a thermal image, with use of artificial neural networks. For this purpose, a series of thermographs of the right hand of eight people was taken, with a thermal imaging camera....

Vertical countermovement jump is a very simple and common method for assessing the jumping ability of athletes. There are different techniques for measurements of the flight height, e.g. using motion capture systems or accelerometers. In this paper for estimating the flight height the measurements coming from the force plates are used. Furthermore...

Although isokinetic tests are very widely used as the screening tool in different groups of athletes, there is still very limited number of studies describing proper shape of isokinetic curve for elite soccer players. Isokinetic evaluations are usually restricted to the analysis of only few values, from hundreds of available parameters. That is why...

The Trefftz method is understood as an approximate method for solving boundary value problems in which the approximate solution is a linear combination of trial functions satisfying exactly the governing equation. The method was proposed by Erich Trefftz in Zürich in 1926 as an alternative to the Ritz method in which the boundary conditions are sat...

The paper deals with a problem of automatic gender recognition based on parameters obtained from the force plates. The ground reaction force is recorded and some selected parameters of the curve are calculated. These parameters are used in this study as inputs to artificial neural network which should recognize if the individual is male or famale....

In the paper a way of people identification, based on ground reaction forces during gait, is presented. The authors established that each individual has an unique gait pattern that can be described by quantitative parameters, calculated using measurements coming from the force plates. Fifteen volunteers took part in this study. Each person walked b...

The paper shows application of the method of fundamental solutions in combination with the radial basis functions for analysis of fluid flow and heat transfer in an internally corrugated tube. Cross-section of such a tube is mathematically described by a cosine function and it can potentially represent a natural duct with internal corrugations, e.g...

The paper presents comparison of the results obtained in a mechanism synthesis by means of some selected evolutionary algorithms. The optimization problem considered in the paper as an example is the dimensional synthesis of the path generating four-bar mechanism. In order to solve this problem, three different artificial intelligence algorithms ar...

Lower limb injury risk assessment was proposed, based on isokinetic examination that is a part of standard athlete’s biomechanical evaluation performed mainly twice a year. Information about non-contact knee injury (or lack of the injury) sustained within twelve months after isokinetic test, confirmed in USG were verified. Three the most common typ...

Objective:
To measure the sensitivity and specificity of differences cut-off values for isokinetic Hcon/Qcon ratio in order to improve the capacity to evaluate (retrospectively) the injury of hamstring muscles in professional soccer screened with knee isokinetic tests.
Design:
Retrospective study.
Methods:
Medical and biomechanical data of pro...

Statement of the Bioethical Committee.
Polish translation from the Bioethical Committee regarding the ethical issues.
(PDF)

Background Hamstring/quadriceps conventional ratio (H/Q) has been widely used in the prediction of anterior cruciate ligament (ACL) injury. However, there is still no consensus on the values that are really predictive for ACL injury in elite male football players.
Objective To verify the value of H/Q predictive for ACL injury in elite male footbal...

This paper presents a determination of the effective viscosity in the Brinkman equation by a numerical simulation of an imaginary physical experiment with a viscometer. The model of a porous medium and the applied method of solution are very simple. In the idealized problem, we consider axial flow through an infinite array of cylindrical rods. Assu...

In the paper three different approaches for the Trefftz method are compared in analysis of the fluid flow between regular bundles of cylindrical fibres. The approximate solution is a linear combination of such trial functions which fulfil exactly the governing equations. The trial functions can be defined in the Cartesian coordinate system (the fir...

In this paper human recognition method is based on dynamic parameters of the human gait. In the method the artificial neural network algorithm is employed. Some parameters of the gait are defined in order to describe and recognize characteristics of gait for each considered individual. In classical approach to human recognition, description of the...

The paper deals with a problem of Carreau fluid flow between corrugated plates. A meshless numerical procedure for solving nonlinear governing equation is constructed using the Picard iteration method in combination with the method of fundamental solutions and the radial basis functions. The dimensionless average velocity and the product of frictio...

The numerical calculations of the velocity field and the component of transverse permeability in the filtration equation for steady, incompressible flow of the generalized Newtonian fluid through the assemblages of cylindrical fibers are presented in this paper. The fibers are arranged regularly in arrays. Flow is transverse with respect to the fib...

Determination of the effective viscosity in the Brinkman’s filtration equation by numerical simulation of an imagined physical experiment in volume flow rate viscometer is presented in this paper. Porous medium is modeled by the bundle of parallel fibers ordered in a regular square array. Such bundle is placed in a square duct. In the first step, a...

In the paper an analysis of fluid flow and heat transfer of a power-law fluid in an internally finned tube with different fin length is conducted. Nonlinear momentum equation of a power-law fluid flow and nonlinear energy equation are solved using the Picard iteration method. Then on each iteration step the solution of inhomogeneous equation consis...

The paper deals with the problem of the peristaltic flow of Newtonian fluid in two-dimensional channel. The problem is considered using stream function and vorticity formulation. The high-order iterative formulation is used in order to transform the nonlinear problem into a hierarchy of inhomogeneous problems which are solved using the method of fu...

This paper deals with the problem of a steady, fully developed, laminar flow of a power-law fluid between corrugated plates. A nonlinear governing equation is transformed into a sequence of linear inhomogeneous equations by the Picard iteration method. At each iteration step, the inhomogeneous equation is solved using the method of particular solut...

In the paper the identification of the time-dependent blood perfusion coefficient is formulated as an inverse problem. The bio-heat conduction problem is transformed into the classical heat conduction problem. Then the transformed inverse problem is solved using the method of fundamental solutions together with the Tikhonov regularization. Some num...

Fluid flow in internally finned tubes is a very important problem from a practical point of view. In the literature there are many different numerical methods which were used for analysis this problem. However to the best knowledge of the authors of the present paper there are no so many papers in which meshless methods were applied for this purpos...

This paper deals with the problem of viscous laminar flow in a wavy channel using the method of fundamental solutions and the radial basis functions. First approximation was obtained when the Reynolds number equals zero, in which the considered problem is homogeneous problem which can be easily solved using the method of fundamental solutions. In o...

In the paper the numerical and experimental results for the dynamics of pendulum with variable mass were described. Mathematical model was developed taking into account the loss of mass, reactive force, air resistance and friction. A corresponding test rig was designed and built in order to validate the numerical results. The purpose of the paper i...

The problem of determining properties of non-Newtonian fluid from the given experimental relation between the mean velocity and the pressure gradient is investigated as an inverse problem.The Lavenberg- Marquardt iteration method was used in order to solve the inverse problem. In the method the solution of the inverse problem is based on solutions...

The system of human locomotion is very complex. Generally we can divide it into the skeletal and muscle systems. The muscle system (muscles) enable to move the body which is formed by the skeletal system (bones). Electromyography is a technique of measurement the electrical activity of muscles which is related with shortening or lengthening of musc...