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Publications in other journals ranked by Ministry of Science and Higher Education
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Affiliation to IPPT PAN

1.Pisarski D., Decentralized stabilization of semi-active vibrating structures, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.003, Vol.100, pp.694-705, 2018
Pisarski D., Decentralized stabilization of semi-active vibrating structures, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.003, Vol.100, pp.694-705, 2018

Abstract:
A novel method of decentralized structural vibration control is presented. The control is assumed to be realized by a semi-active device. The objective is to stabilize a vibrating system with the optimal rates of decrease of the energy. The controller relies on an easily implemented decentralized switched state-feedback control law. It uses a set of communication channels to exchange the state information between the neighboring subcontrollers. The performance of the designed method is validated by means of numerical experiments performed for a double cantilever system equipped with a set of elastomers with controlled viscoelastic properties. In terms of the assumed objectives, the proposed control strategy significantly outperforms the passive damping cases and is competitive with a standard centralized control. The presented methodology can be applied to a class of bilinear control systems concerned with smart structural elements.

Keywords:
structural control, decentralized control, smart structures, modular structures, stabilization

2.Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.012, Vol.100, pp.926-939, 2018
Popławski B., Mikułowski G., Mróz A., Jankowski Ł., Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2017.08.012, Vol.100, pp.926-939, 2018

Abstract:
This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss–frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.

Keywords:
Damping of vibrations, Smart structures, Semi-active control, Decentralized control, Truss-frame nodes

3.Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12258, Vol.32, No.4, pp.304-318, 2017
Błachowski B., An Y., Spencer Jr. B.F., Ou J., Axial strain accelerations approach for damage localization in statically determinate truss structures, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12258, Vol.32, No.4, pp.304-318, 2017

Abstract:
This work proposes an efficient and reliable method for damage localization in truss structures. The damage is localized on the basis of measured acceleration signals of the structure followed by simple statistical signal processing. It has three main advantages over many existing methods. Firstly, it can be directly applied to real engineering structures without the need of identifying modal parameters or solving any global optimization problem. Secondly, the proposed method has higher sensitivity to damage than some other frequently used methods and allows to localize damage as small as a few percents. Thirdly, it is a model-free method, which does not require precise finite element model development or updating. Validation of the method has been conducted on numerical examples and laboratory-scale trusses. Two types of frequently used trusses have been selected for this study, namely Howe and Bailey trusses. The presented experimental validation of the method shows its efficiency and robustness for damage localization in truss structures.

Keywords:
structural health monitoring, truss structures, damage detection

4.Fras T., Murzyn A., Pawłowski P., Defeat mechanisms provided by slotted add-on bainitic plates against small-calibre 7.62 mm x 51 AP projectiles., INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2017.01.015, Vol.103, pp.241-253, 2017
Fras T., Murzyn A., Pawłowski P., Defeat mechanisms provided by slotted add-on bainitic plates against small-calibre 7.62 mm x 51 AP projectiles., INTERNATIONAL JOURNAL OF IMPACT ENGINEERING, ISSN: 0734-743X, DOI: 10.1016/j.ijimpeng.2017.01.015, Vol.103, pp.241-253, 2017

Abstract:
Thin steel plates with an array of holes, i.e. perforated plates, are used as a passive add-on improving protective properties of armours against small-calibre projectiles. A number of holes in such plates increases the probability of asymmetrical contact between the plate and the projectile, due to which small-calibre projectiles may be destabilized or fragmented before they reach the main-armour. The aim of the study is to analyse the defeat mechanisms provided by 4-mm-thick slotted super-bainitic plates (Pavise™ SBS 600P) against hard-core 7.62mm P80 0.30 AP×51 (0.308 Win) projectiles. To show the dependence between the hit-point and projectile failure, moments when projectiles hit the pre-armour plate were recorded by an ultra-high speed camera and their behaviour after the impact was captured by the flash X-ray radiography. The obtained results complemented by the Lagrangian FEM analysis confirm that slotted steel plates have high protection effectiveness against small-calibre projectiles.

Keywords:
Light-weight ballistic protectionPerforated add-on armourSuper-bainitic steelArmour-piercing (AP) projectile

5.Graczykowski C., Pawłowski P., Exact physical model of magnetorheological damper, Applied Mathematical Modelling, ISSN: 0307-904X, DOI: 10.1016/j.apm.2017.02.035, Vol.47, pp.400-424, 2017
Graczykowski C., Pawłowski P., Exact physical model of magnetorheological damper, Applied Mathematical Modelling, ISSN: 0307-904X, DOI: 10.1016/j.apm.2017.02.035, Vol.47, pp.400-424, 2017

Abstract:
This paper attempts to fill the gap in the literature by introducing and discussing an enhanced physical model of the MR damper. The essence of the presented model is to combine the effect of compressibility of the MR fluid enclosed in each chamber with the effect of blocking the flow between the chambers in the case of a low pressure difference. As it will be shown, the concurrence of both considered phenomena significantly affects mechanical behaviour of the damper, influences its dissipative characteristics, and in particular, it is the reason behind the distinctive ‘z-shaped’ force–velocity hysteresis loops observed in experiments. The paper presents explanation of the observed phenomena, detailed derivation of the thermodynamic equations governing response of the damper, their implementation for various constitutive models of the magnetorheological fluid and, finally, formulation of the corresponding reduced and parametric models. Experimental validation shows that proper identification of physical parameters of the proposed mathematical model yields the correct shapes of force–velocity hysteresis loops.

Keywords:
Magnetorheological fluid dampers, Smart fluids, Hysteresis modelling

6.Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, Vol.394, pp.333-347, 2017
Bajer C.I., Pisarski D., Szmidt T., Dyniewicz B., Intelligent damping layer under a plate subjected to a pair of masses moving in opposite directions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.01.046, Vol.394, pp.333-347, 2017

Abstract:
Reducing displacements of a plate vibrating under a pair of masses traveling in opposite directions can be improved by adding a smart subsoil instead of a classical damping layer. We propose a material that acts according to the instantaneous state of the plate, i.e., its displacements and velocity. Such an intelligent damping layer reduces vertical displacements even by 40%–60%, depending on the type of load and the assumed objective function. Existing materials enable the application of the proposed layer in a semi-active mode. The passive mode can be applied with materials exhibiting direction-dependent viscosity.

Keywords:
Plate vibration, Moving load, Intelligent damping layer, Semi-active damping

7.Szmidt T., Pisarski D., Bajer C.I., Dyniewicz B., Double-beam cantilever structure with embedded intelligent damping block: Dynamics and control, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.04.033, Vol.401, pp.127-138, 2017
Szmidt T., Pisarski D., Bajer C.I., Dyniewicz B., Double-beam cantilever structure with embedded intelligent damping block: Dynamics and control, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.04.033, Vol.401, pp.127-138, 2017

Abstract:
In this paper, a semi-active method to control the vibrations of twin beams connected at their tips by a smart damping element is investigated. The damping element can be made of a magnetorheological elastomer or a smart material of another type, for instance, vacuum packed particles. What is crucial is the ability to modify the storage and loss moduli of the damping block by means of devices attached directly to the vibrating structure. First, a simple dynamical model of the system is proposed. The continuous model is discretized using the Galerkin procedure. Then, a practical state-feedback control law is developed. The control strategy aims at achieving the best instantaneous energy dissipation of the system. Numerical simulations confirm its effectiveness in reducing free vibrations. The proposed control strategy appears to be robust in the sense that its application does not require any knowledge of the initial conditions imposed on the structure, and its performance is better than passive solutions, especially for the system induced in the first mode.

Keywords:
Vibration control, Double-beam structure, Sandwich beam, Magnetorheological elastomer, Semi-active damping, Stabilization

8.Zieliński T.G., Microstructure representations for sound absorbing fibrous media: 3D and 2D multiscale modelling and experiments, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.07.047, Vol.409, pp.112-130, 2017
Zieliński T.G., Microstructure representations for sound absorbing fibrous media: 3D and 2D multiscale modelling and experiments, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2017.07.047, Vol.409, pp.112-130, 2017

Abstract:
The paper proposes and investigates computationally-efficient microstructure representations for sound absorbing fibrous media. Three-dimensional volume elements involving non-trivial periodic arrangements of straight fibres are examined as well as simple two-dimensional cells. It has been found that a simple 2D quasi-representative cell can provide similar predictions as a volume element which is in general much more geometrically accurate for typical fibrous materials. The multiscale modelling allowed to determine the effective speeds and damping of acoustic waves propagating in such media, which brings up a discussion on the correlation between the speed, penetration range and attenuation of sound waves. Original experiments on manufactured copper-wire samples are presented and the microstructure-based calculations of acoustic absorption are compared with the corresponding experimental results. In fact, the comparison suggested the microstructure modifications leading to representations with non-uniformly distributed fibres.

Keywords:
Sound absorption, Fibrous materials, Multiscale modelling, Microstructure representations

9.Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, Vol.38, No.6, pp.922-933, 2017
Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, Vol.38, No.6, pp.922-933, 2017

Abstract:
In this paper, a semi-active damping approach is used for reduction of vibrations in a laboratory drivetrain system. The considered drivetrain system is powered by an electric, asynchronous motor at the one side and loaded with a harmonically varying torque on the other side. Here, an influence of electromechanical interaction, i.e., an electromechanical coupling, between the electric motor and the mechanical system has been taken into consideration. The harmonic load signal induces torsional vibrations in the system, which in the steady-state phase of motion become periodic. The aim of the work is to determine the optimal control function for a semi-active damping element, leading to vibration reduction and considering only the steady-state phase of system motion. The optimal control is derived by using a semi-analytical approach based on the optimal control theory aided with supplementary numerical computations. The proposed methodology is fully general, and it can be directly applied to any type of a periodically oscillating system.

Keywords:
electric motor, electromechanical coupling, optimal control, periodic torsional vibrations, semi-active damping

10.Pisarski D., Myśliński A., Online adaptive algorithm for optimal control of structures subjected to travelling loads, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2321, Vol.38, No.6, pp.1168-1186, 2017
Pisarski D., Myśliński A., Online adaptive algorithm for optimal control of structures subjected to travelling loads, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2321, Vol.38, No.6, pp.1168-1186, 2017

Abstract:
The problem of adaptive optimal semiactive control of a structure subjected to a moving load is studied. The control is realised by a change of damping of the structure’s supports. The results presented in the previous works of the authors demonstrate that switched optimal controls can be very efficient at reducing the vibration levels of the structure. On the other hand, these controls exhibit a high sensitivity to changes of the speed of the travelling load. The aim of this paper is to develop an algorithm that enables real-time adaptation of the optimal controls according to both the measured speed of the travelling load and the estimated state of the structure. The control objective is to provide smooth passage for the vehicles and reduce the material stresses on the carrying structures. The designed adaptive algorithm uses reference optimal controls computed for constant speeds and a set of functions describing the sensitivity of the system dynamics to the measured parameters. The convergence of the algorithm, as well as aspects of its implementation, is studied. The performance of the proposed method is validated by means of numerical simulations conducted for different travelling speed scenarios. In the assumed objective functional, the proposed adaptive controller can outperform the reference optimal solutions by over 50%. The practicality of the proposed method should attract the attention of practising engineers.

Keywords:
Adaptive control, Moving load, Online optimal control, Sensitivity analysis, Structural vibration control

11.Nowak K.M., Nowak Ł.J., Experimental validation of the tuneable diaphragm effect in modern acoustic stethoscopes, Postgraduate Medical Journal, ISSN: 0032-5473, DOI: 10.1136/postgradmedj-2017-134810, pp.1-5, 2017
Nowak K.M., Nowak Ł.J., Experimental validation of the tuneable diaphragm effect in modern acoustic stethoscopes, Postgraduate Medical Journal, ISSN: 0032-5473, DOI: 10.1136/postgradmedj-2017-134810, pp.1-5, 2017

Abstract:
Purpose The force with which the diaphragm chestpiece of a stethoscope is pressed against the body of a patient during an auscultation examination introduces the initial stress and deformation to the diaphragm and the underlying tissues, thus altering the acoustic parameters of the sound transmission path. If the examination is performed by an experienced physician, he will intuitively adjust the amount of the force in order to achieve the optimal sound quality. However, in case of becoming increasingly popular autodiagnosis and telemedicine auscultation devices with no such feedback mechanisms, the question arises regarding the influence of the possible force mismatch on the parameters of the recorded signal. Design The present study describes the results of the experimental investigations on the relation between pressure applied to the chestpiece of a stethoscope and parameters of the transmitted bioacoustic signals. The experiments were carried out using various stethoscopes connected to a force measurement system, which allowed to maintain fixed pressure during auscultation examinations. The signals were recorded during examinations of different volunteers, at various auscultation sites. Results The obtained results reveal strong individual and auscultation-site variability. Conclusions It is concluded that the underlying tissue deformation is the primary factor that alters the parameters of the recorded signals.

12.Orłowska A., Graczykowski C., Gałęzia A., The effect of prestress force magnitude on the natural bending frequencies of the eccentrically prestressed glass fibre reinforced polymer composite beams, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/0021998317740202, pp.1-14, 2017
Orłowska A., Graczykowski C., Gałęzia A., The effect of prestress force magnitude on the natural bending frequencies of the eccentrically prestressed glass fibre reinforced polymer composite beams, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/0021998317740202, pp.1-14, 2017

Abstract:
This paper studies the effect of prestress force magnitude on natural frequencies and dynamic behaviour of eccentrically prestressed glass fibre reinforced polymer composite beams, including the theoretical background, numerical results and experimental verification. The term prestress indicates the initial tensile stress applied to the fibres embedded in selected external layers of the composite material. First, the paper presents the theoretical background of the finite element method modelling of prestressed composites. Then, the results of numerical simulations conducted for a five-layered glass-epoxy composite beam are presented. The natural frequencies corresponding to three initial bending modes are analyzed for different prestressing force levels and for different fibre volume content. Finally, the results are verificated by experimental modal analysis conducted on three different glass-epoxy composite specimens of various mechanical parameters. Both the numerical results obtained from finite element method and the experimental results obtained from experimental modal analysis reveal that the first bending frequency increases and the two subsequent bending frequencies decrease due to the prestressing force. The comparison of numerical and experimental data confirms the effect and allows to quantify the influence that the prestress force has on the natural frequencies of composites, which is an interesting and practically relevant phenomenon.

Keywords:
Prestressed structures, laminated composites, prestressed reinforced composites, glass fibre reinforced polymer composite materials, vibrations, finite element method

13.Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017
Meissner M., Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2017.01.020, Vol.120, pp.111-119, 2017

Abstract:
A small rectangular room with hard walls has a number of acoustic flaws and the most serious drawback is a long reverberation time. A technique commonly used for improving room acoustics consists in increasing a sound absorption on a ceiling. In this study, the impact of acoustical treatment of a ceiling on reverberant properties of a small rectangular room was examined. Changes in the modal reverberation time due to this treatment were investigated by the analytical method. As was evidenced by calculations, the initial increase in a sound absorption on a ceiling causes a substantial decrease in the modal reverberation time and a treatment efficiency decreases with a further absorption increase. It was found also that for a room with hard walls statistical and wave theories give the same result as the modal reverberation time for oblique modes and the Sabine’s reverberation time are identical. A more detailed information about reverberant properties of a room was provided by the numerical method employing a backward integration of the squared room impulse response. Using this method, global and local reverberation parameters were determined. Numerical simulations discovered a quite good agreement between global and local reverberation time and high differences between global and local early decay time resulting from a nonlinear shape of a decay curve. Therefore, one can conclude that the global decay times characterize reasonably well a reverberation process in a late stage of sound decay but they are not correctly describe this process in an initial stage.

Keywords:
Small room acoustics, Modal expansion method, Room impulse response, Reverberation time, Early decay time

14.Bajer C.I., Dyniewicz B., Shillor M., A Gao beam subjected to a moving inertial point load, Mathematics and Mechanics of Solids, ISSN: 1081-2865, DOI: 10.1177/1081286517718229, pp.1-12, 2017
Bajer C.I., Dyniewicz B., Shillor M., A Gao beam subjected to a moving inertial point load, Mathematics and Mechanics of Solids, ISSN: 1081-2865, DOI: 10.1177/1081286517718229, pp.1-12, 2017

Abstract:
A model for the dynamics of a Gao elastic or viscoelastic nonlinear beam that is subject to a horizontally moving vertical point-force is modeled and computationally studied. In particular, the behavior and vibrations of the beam as the mass is moving on it is investigated. Such problems arise naturally in transportation systems with rails. A time-marching finite element numerical algorithm for the problem is developed and implemented. Results of representative simulations are depicted and compared to the behavior of a linear Euler beam with a moving mass.

Keywords:
Gao beam, moving inertial point load, Finite Element simulations, beam vibration

15.Nowak Ł.J., Nowak K.M., Acoustic characterization of stethoscopes using auscultation sounds as test signals, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, DOI: 10.1121/1.4978524, Vol.141, No.3, pp.1940-1946, 2017
Nowak Ł.J., Nowak K.M., Acoustic characterization of stethoscopes using auscultation sounds as test signals, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 0001-4966, DOI: 10.1121/1.4978524, Vol.141, No.3, pp.1940-1946, 2017

Abstract:
The present study introduces a detailed methodology which can be applied for objective evaluation and comparison of the acoustic parameters of medical stethoscopes using auscultation sounds as test signals. The described approach allows taking into account the acoustic coupling between the body of an auscultated patient and the chest piece of a stethoscope. Information obtained from additional, synchronized electrocardiography measurements is used to extract short, specific fragments of recordings, defined as acoustic events. Analysis of the spectral characteristics of many acoustic events allows us to compare the acoustic properties of various stethoscopes and to estimate the measurement uncertainty. The exemplary results of the comparative evaluation of acoustic properties of bell and diaphragm-type chest pieces of a single stethoscope are presented. The results show that the frequency characteristics of the signals obtained using both examined chest pieces under the conditions of the performed examinations are very similar.

16.Jundziłł A., Pokrywczyńska M., Adamowicz J., Kowalczyk T., Nowacki M., Bodnar M., Marszałek A., Frontczak-Baniewicz M.M., Mikułowski G., Kloskowski T., Gatherwright J., Drewa T., Vascularization Potential of Electrospun Poly(L-Lactide-co-Caprolactone) Scaffold: The Impact for Tissue Engineering, Medical Science Monitor, ISSN: 1643-3750, DOI: 10.12659/MSM.899659, Vol.23, pp.1540-1551, 2017
Jundziłł A., Pokrywczyńska M., Adamowicz J., Kowalczyk T., Nowacki M., Bodnar M., Marszałek A., Frontczak-Baniewicz M.M., Mikułowski G., Kloskowski T., Gatherwright J., Drewa T., Vascularization Potential of Electrospun Poly(L-Lactide-co-Caprolactone) Scaffold: The Impact for Tissue Engineering, Medical Science Monitor, ISSN: 1643-3750, DOI: 10.12659/MSM.899659, Vol.23, pp.1540-1551, 2017

Abstract:
BACKGROUND:
Electrospun nanofibers have widespread putative applications in the field of regenerative medicine and tissue engineering. When compared to naturally occurring collagen matrices, electrospun nanofiber scaffolds have two distinct advantages: they do not induce a foreign body reaction and they are not at risk for biological contamination. However, the exact substrate, structure, and production methods have yet to be defined.
MATERIAL AND METHODS:
In the current study, tubular-shaped poly(L-lactide-co-caprolactone) (PLCL) constructs produced using electrospinning technology were evaluated for their potential application in the field of tissue regeneration in two separate anatomic locations: the skin and the abdomen. The constructs were designed to have an internal diameter of 3 mm and thickness of 200 μm. Using a rodent model, 20 PLCL tubular constructs were surgically implanted in the abdominal cavity and subcutaneously. The constructs were then evaluated histologically using electron microscopy at 6 weeks post-implantation.
RESULTS:
Histological evaluation and analysis using scanning electron microscopy showed that pure scaffolds by themselves were able to induce angiogenesis after implantation in the rat model. Vascularization was observed in both tested groups; however, better results were obtained after intraperitoneal implantation. Formation of more and larger vessels that migrated inside the scaffold was observed after implantation into the peritoneum. In this group no evidence of inflammation and better integration of scaffold with host tissue were noticed. Subcutaneous implantation resulted in more fibrotic reaction, and differences in cell morphology were also observed between the two tested groups.
CONCLUSIONS:
This study provides a standardized evaluation of a PLCL conduit structure in two different anatomic locations, demonstrating the excellent ability of the structure to achieve vascularization. Functional, histological, and mechanical data clearly indicate prospective clinical utilization of PLCL in critical size defect regeneration.

Keywords:
Polymers, Regenerative medicine, Tissue Engineering, Tissue Scaffolds, Urinary Diversion

17.Błachowski B.D., Tauzowski P., Lógó J., Modal Approximation Based Optimal Design of Dynamically Loaded Plastic Structures, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11016, pp.1-6, 2017
Błachowski B.D., Tauzowski P., Lógó J., Modal Approximation Based Optimal Design of Dynamically Loaded Plastic Structures, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.11016, pp.1-6, 2017

Abstract:
The purpose of this study is to present an optimal design procedure for elasto-plastic structures subjected to impact loading. The proposed method is based on mode approximation of the displacement field and assumption of constant acceleration of impacted structure during whole time of deformation process until the plastic displacement limit is reached. Derivation of the method begins with the application of the principle of conservation of linear momentum, followed by determination of inertial forces. The final stage of the method utilizes an optimization technique in order to find a minimum weight structure. Eventually, effectiveness and usefulness of the proposed method is demonstrated on the example of a planar truss structure subjected to dynamic loading caused by a mass impacting the structure with a given initial velocity.

Keywords:
structural dynamics, optimal design, elasto-plastic structures, short-time dynamic loading

18.Chudzikiewicz A., Bogacz R., Kostrzewski M., Konowrocki R., Condition monitoring of railway track systems by using acceleration signals on wheelset axle-boxes, Transport, ISSN: 1648-4142, DOI: 10.3846/16484142.2017.1342101, pp.1-12, 2017
Chudzikiewicz A., Bogacz R., Kostrzewski M., Konowrocki R., Condition monitoring of railway track systems by using acceleration signals on wheelset axle-boxes, Transport, ISSN: 1648-4142, DOI: 10.3846/16484142.2017.1342101, pp.1-12, 2017

Abstract:
The aim of this paper is to demonstrate the possibilities of estimating the track condition using axle-boxes and car-bodies motions described by acceleration signals. In the paper, the results presented indicate the condition of tracks obtained from the preliminary investigation on the test track. Furthermore, the results from the supervised runs (on Polish Railway Lines) of electric multiple unit (EMU-ED74) with the prototype of track quality monitoring system installed on-board are described. As track quality indicator (TQI) algorithm, used in the mentioned prototype, a modified Karhunen–Loève transformation is used in preliminary preparing acceleration signals. The transformation is used to extract the principal dynamics from measurement data. Obtained results are compared to other methods of evaluating the geometrical track quality, namely methods which apply the Jsynth Synthetic Coefficient and Five Parameters of Defectiveness W5. The results from the investigation showed that track condition estimation is possible with acceptable accuracy for in-service use and for defining cost-effective maintenance strategies.

Keywords:
railway track monitoring, wheel–rail interaction, track quality indicator, acceleration signals, experimental investigation, track degradation.

19.Będkowski J., Röhling T., Online 3D LIDAR Monte Carlo localization with GPU acceleration, Industrial Robot: An International Journal, ISSN: 0143-991X, DOI: 10.1108/IR-11-2016-0309, Vol.44, No.4, pp.442-456, 2017
Będkowski J., Röhling T., Online 3D LIDAR Monte Carlo localization with GPU acceleration, Industrial Robot: An International Journal, ISSN: 0143-991X, DOI: 10.1108/IR-11-2016-0309, Vol.44, No.4, pp.442-456, 2017

Abstract:
*Purpose*

This paper aims to focus on real-world mobile systems, and thus propose relevant contribution to the special issue on “Real-world mobile robot systems”. This work on 3D laser semantic mobile mapping and particle filter localization dedicated for robot patrolling urban sites is elaborated with a focus on parallel computing application for semantic mapping and particle filter localization. The real robotic application of patrolling urban sites is the goal; thus, it has been shown that crucial robotic components have reach high Technology Readiness Level (TRL).

*Design/methodology/approach*

Three different robotic platforms equipped with different 3D laser measurement system were compared. Each system provides different data according to the measured distance, density of points and noise; thus, the influence of data into final semantic maps has been compared. The realistic problem is to use these semantic maps for robot localization; thus, the influence of different maps into particle filter localization has been elaborated. A new approach has been proposed for particle filter localization based on 3D semantic information, and thus, the behavior of particle filter in different realistic conditions has been elaborated. The process of using proposed robotic components for patrolling urban site, such as the robot checking geometrical changes of the environment, has been detailed.

*Findings*

The focus on real-world mobile systems requires different points of view for scientific work. This study is focused on robust and reliable solutions that could be integrated with real applications. Thus, new parallel computing approach for semantic mapping and particle filter localization has been proposed. Based on the literature, semantic 3D particle filter localization has not yet been elaborated; thus, innovative solutions for solving this issue have been proposed. Recently, a semantic mapping framework that was already published was developed. For this reason, this study claimed that the authors’ applied studies during real-world trials with such mapping system are added value relevant for this special issue.

*Research limitations/implications*

The main problem is the compromise between computer power and energy consumed by heavy calculations, thus our main focus is to use modern GPGPU, NVIDIA PASCAL parallel processor architecture. Recent advances in GPGPUs shows great potency for mobile robotic applications, thus this study is focused on increasing mapping and localization capabilities by improving the algorithms. Current limitation is related with the number of particles processed by a single processor, and thus achieved performance of 500 particles in real-time is the current limitation. The implication is that multi-GPU architectures for increasing the number of processed particle can be used. Thus, further studies are required.

*Practical implications*

The research focus is related to real-world mobile systems; thus, practical aspects of the work are crucial. The main practical application is semantic mapping that could be used for many robotic applications. The authors claim that their particle filter localization is ready to integrate with real robotic platforms using modern 3D laser measurement system. For this reason, the authors claim that their system can improve existing autonomous robotic platforms. The proposed components can be used for detection of geometrical changes in the scene; thus, many practical functionalities can be applied such as: detection of cars, detection of opened/closed gate, etc. […] These functionalities are crucial elements of the safe and security domain.

*Social implications*

Improvement of safe and security domain is a crucial aspect of modern society. Protecting critical infrastructure plays an important role, thus introducing autonomous mobile platforms capable of supporting human operators of safe and security systems could have a positive impact if viewed from many points of view.

*Originality/value*

This study elaborates the novel approach of particle filter localization based on 3D data and semantic mapping. This original work could have a great impact on the mobile robotics domain, and thus, this study claims that many algorithmic and implementation issues were solved assuming real-task experiments. The originality of this work is influenced by the use of modern advanced robotic systems being a relevant set of technologies for proper evaluation of the proposed approach. Such a combination of experimental hardware and original algorithms and implementation is definitely an added value.

Keywords:
3D laser, Monte Carlo localization, Parallel computing, Particle filter localization, Semantic mapping, Unmanned ground vehicle