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Affiliation to IPPT PAN

1.Chikahiro Y., Ario I., Pawłowski P., Graczykowski C., Holnicki-Szulc J., Optimization of reinforcement layout of scissor-type bridge using differential evolution algorithm, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12432, pp.1-16, 2019
Chikahiro Y., Ario I., Pawłowski P., Graczykowski C., Holnicki-Szulc J., Optimization of reinforcement layout of scissor-type bridge using differential evolution algorithm, Computer-Aided Civil and Infrastructure Engineering, ISSN: 1093-9687, DOI: 10.1111/mice.12432, pp.1-16, 2019

Abstract:
Scissors mechanisms are commonly used in safety engineering during the construction of temporary structures, owing to their inherent advantages of foldability, transformability, and reusability.We effectively utilized these scissors mechanism features to develop a lightweight, deployable emergency Mobile Bridge (MB) based on optimization, and control of the folding structure. Here, we discuss the problems of optimal reinforcement layout for the MB by formulating and solving three optimization problems, namely: (a) the load capacity maximization problem, (b) the weight minimization problem, and (c) coupling the load capacity maximization problem and the weight minimization problem. The potential benefits resulting from the application of reinforcement were evaluated using a combination of finite element analysis and an optimization algorithm based on the differential evolution method. The results demonstrate the significant positive influence of the additional reinforcing members. In particular, the limit load was increased by over 10 times, while the weight was decreased to approximately half. The proposed methodology enabled the development of a substantially improved version of the MB characterized by a higher load capacity and lower weight in comparison to the initial bridge design.

2.Nakielski P., Pierini F., Blood interactions with nano- and microfibers: recent advances, challenges and applications in nano- and microfibrous hemostatic agents, Acta Biomaterialia, ISSN: 1742-7061, DOI: 10.1016/j.actbio.2018.11.029, Vol.84, pp.63-76, 2019
Nakielski P., Pierini F., Blood interactions with nano- and microfibers: recent advances, challenges and applications in nano- and microfibrous hemostatic agents, Acta Biomaterialia, ISSN: 1742-7061, DOI: 10.1016/j.actbio.2018.11.029, Vol.84, pp.63-76, 2019

Abstract:
Nanofibrous materials find a wide range of applications, such as vascular grafts, tissue-engineered scaffolds, or drug delivery systems. This phenomenon can be attributed to almost arbitrary biomaterial modification opportunities created by a multitude of polymers used to form nanofibers, as well as by surface functionalization methods. Among these applications, the hemostatic activity of nanofibrous materials is gaining more and more interest in biomedical research. It is therefore crucial to find both materials and nanofiber structural properties that affect organism responses. The present review critically analyzes the response of blood elements to natural and synthetic polymers, and their blends and composites. Also assessed in this review is the incorporation of pro-coagulative substances or drugs that can decrease bleeding time. The review also discusses the main animal models that were used to assess hemostatic agent safety and effectiveness.

Keywords:
Blood-biomaterial interactions, Coagulation, Electrospinning, Nanofibers, Platelets, Hemorrhage

3.von Tiedemann P., Maciol K., Preis J., Sajkiewicz P., Frey H., Rapid One-Pot Synthesis of Tapered Star Copolymers via Ultra-Fast Coupling of Polystyryllithium Chain Ends, Polymer Chemistry, ISSN: 1759-9954, DOI: 10.1039/C8PY01656A, pp.1-7, 2019
von Tiedemann P., Maciol K., Preis J., Sajkiewicz P., Frey H., Rapid One-Pot Synthesis of Tapered Star Copolymers via Ultra-Fast Coupling of Polystyryllithium Chain Ends, Polymer Chemistry, ISSN: 1759-9954, DOI: 10.1039/C8PY01656A, pp.1-7, 2019

Abstract:
Highly efficient stoichiometric coupling of sterically hindered polystyryllithium (PS-Li) chain ends was achieved using tetra[3-(chloro-dimethylsilyl)propyl]silane (TCDMSPS) as the linking agent. Based on the disparate reactivities of isoprene (I, rI = 11.0) and styrene (S, rS = 0.049) in the anionic copolymerization in nonpolar media, poly(isoprene0.5-grad-styrene0.5) (P(I0.5-grad-S0.5)) tapered 4-arm star copolymers were synthesized in only two steps. The tapered 4-arm star copolymers (Mwtargeted = 40 to 160 kg mol-1) were synthesized with high star functionalities f (Mw,star/Mw,arm = 3.68 – 3.98), low dispersity (Ð = 1.08 – 1.15) and minimal residual precursor content (2-8 wt%), avoiding fractionation or other purification methods. Coupling kinetics measurements revealed that for the synthesis of polystyrene (PS) 4-arm stars (12 kg mol-1) a coupling efficiency of 98% was already achieved within 2 minutes. All star polymers were analyzed by size exclusion chromatography (SEC) viscometry with universal calibration (UC) as well as NMR spectroscopy. Well-defined nanofibers from the tapered copolymer stars were obtained via electrospinning.

4.Graczykowski C., Faraj R., Development of control systems for fluid-based adaptive impact absorbers, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2018.12.006, Vol.122, No.2019, pp.622-641, 2019
Graczykowski C., Faraj R., Development of control systems for fluid-based adaptive impact absorbers, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2018.12.006, Vol.122, No.2019, pp.622-641, 2019

Abstract:
The paper presents development, evaluation and comparison of various control systems for adaptive fluid-based absorbers serving for absorption of the impact loading. The investigations concern two competitive approaches: i) standard control systems with single determination of the optimal system path based on identified impact conditions, and ii) newly-developed control systems with on-line determination and update of the system path during the process. It is revealed that low robustness of the standard control systems to imprecise impact identification and unknown disturbances results from the assumed path-determination approach and utilized simple path-tracking methods. The proposed solution to this problem is application of the innovative control systems, which utilize Automatic Path Finding and Automatic Path Update algorithms based on full kinematic feedback as well as Hybrid Path Tracking method dedicated for fluid-based absorbers. The introduced approach to absorber control is used to develop three different self-adaptive systems of increasing complexity and robustness. The favourable capabilities of proposed systems including no need for impact identification, high robustness against force disturbances and reduction of leakages influence are proved. Detailed discussion is presented using the illustrative example of single-chamber adaptive pneumatic shock-absorber mitigating impact loading.

Keywords:
Adaptive Impact Absorption, Automatic Path Finding, Automatic Path Update, Full kinematic feedback, Hybrid Path Tracking, Self-adaptive system, Pneumatic shock-absorber

5.Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Klimonda Z., Karwat P., Roszkowska-Purska K., Gumowska M., Litniewski J., Monitoring breast cancer response to neoadjuvant chemotherapy with ultrasound signal statistics and integrated backscatter , PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0213749 , Vol.14, No.3, pp.1-15, 2019
Piotrzkowska-Wróblewska H., Dobruch-Sobczak K., Klimonda Z., Karwat P., Roszkowska-Purska K., Gumowska M., Litniewski J., Monitoring breast cancer response to neoadjuvant chemotherapy with ultrasound signal statistics and integrated backscatter , PLOS ONE, ISSN: 1932-6203, DOI: 10.1371/journal.pone.0213749 , Vol.14, No.3, pp.1-15, 2019

Abstract:
Background Neoadjuvant chemotherapy (NAC) is used in patients with breast cancer to reduce tumor focus, metastatic risk, and patient mortality. Monitoring NAC effects is necessary to capture resistant patients and stop or change treatment. The existing methods for evaluating NAC results have some limitations. The aim of this study was to assess the tumor response at an early stage, after the first doses of the NAC, based on the variability of the backscattered ultrasound energy, and backscatter statistics. The backscatter statistics has not previously been used to monitor NAC effects. Methods The B-mode ultrasound images and raw radio frequency data from breast tumors were obtained using an ultrasound scanner before chemotherapy and 1 week after each NAC cycle. The study included twenty-four malignant breast cancers diagnosed in sixteen patients and qualified for neoadjuvant treatment before surgery. The shape parameter of the homodyned K distribution and integrated backscatter, along with the tumor size in the longest dimension, were determined based on ultrasound data and used as markers for NAC response. Cancer tumors were assigned to responding and non-responding groups, according to histopathological evaluation, which was a reference in assessing the utility of markers. Statistical analysis was performed to rate the ability of markers to predict the final NAC response based on data obtained after subsequent therapeutic doses. Results Statistically significant differences (p<0.05) between groups were obtained after 2, 3, 4, and 5 doses of NAC for quantitative ultrasound markers and after 5 doses for the assessment based on maximum tumor dimension. Statistical analysis showed that, after the second and third NAC courses the classification based on integrated backscatter marker was characterized by an AUC of 0.69 and 0.82, respectively. The introduction of the second quantitative marker describing the statistical properties of scattering increased the corresponding AUC values to 0.82 and 0.91. Conclusions Quantitative ultrasound information can characterize the tumor's pathological response better and at an earlier stage of therapy than the assessment of the reduction of its dimensions. The introduction of statistical parameters of ultrasonic backscatter to monitor the effects of chemotherapy can increase the effectiveness of monitoring and contribute to a better personalization of NAC therapy.

6.Postek E., Sadowski T., Impact model of WC/Co composite, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2019.01.084, No.213, pp.231-242, 2019
Postek E., Sadowski T., Impact model of WC/Co composite, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2019.01.084, No.213, pp.231-242, 2019

Abstract:
WC/Co composite is a standard hard material used for the production of cutting tools. It has both very good thermo-mechanical and wear properties. During the cutting, process tools are subjected to impact loading and gradual degradation due to high-stress concentrations. This loading induced deterioration is complex process still not well investigated and explained.Up till now the dynamic response of the WC/Co composite was analysed under dynamic impulse compressive loading [1]. However, the behaviour of the above two-phase composite under impacts conditions was not investigated in details. In the presented micromechanical approach the real material structure geometry of the internal structure can be performed including spatial distribution of: (1) WC grains and their dimensions, (2) volume content of plastic Co binder with their thickness, (3) system of grain/binder interfaces and (4) cracks initiated and developed during impulse loading, (5) possible brittle grains rotation.The results reveal the dependence of the microcracking processes and the stress distribution on impact velocity and presence of discontinuities in the Co binder and the interface zone between the binders and the grains. The microcracks system was evaluated by the damage parameter according to Kachanov, 1986 [62].

Keywords:
Cermet; Impact load; Microcracking; Cohesive elements; Numerical modelling;

7.Massaq A., Rusinek A., Klosak M., Bahi S., Arias A., Strain rate effect on the mechanical behavior of polyamide composites under compression loading, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2019.01.101, Vol.214, pp.114-122, 2019
Massaq A., Rusinek A., Klosak M., Bahi S., Arias A., Strain rate effect on the mechanical behavior of polyamide composites under compression loading, COMPOSITE STRUCTURES, ISSN: 0263-8223, DOI: 10.1016/j.compstruct.2019.01.101, Vol.214, pp.114-122, 2019

Abstract:
This paper presents an experimental study on the effect of strain rate on the compressive behavior of polyamide composites. Contrary to thermoset woven reinforced composites, thermoplastic woven reinforced composites have always received less interest despite its excellent damage and impact resistances. In this context, this work aims to study the behavior of fiber reinforced thermoplastic composites submitted to high strain rate in compression. The tested material is a thermoplastic composite made of armor tissue of equilibrate glass fiber and the matrix is composed of Polyamide 6 (PA6/Glass). The material is prepared with the fibers woven in 0/90 direction.The compressive mechanical response of PA6/Glass composite was determined in the transverse and longitudinal fibers directions at quasi-static and high strain rates. The hydraulic machine and Split Hopkinson Pressure Bar experiments were conducted to determine the dynamic and quasi static compressive deformation and fracture of the PA6/Glass at strain rates from 10−5 s−1 to 1 s−1 and 100 s−1 to 2500 s−1, respectively.In this work, the main goals were to determine the strain rate effect on: elastic modulus, failure stress and failure energy as a function of the loading direction. The strain rate sensitivity of the failure stress level and failure energy were observed. In addition, the failure mechanism was characterized by examining the fracture surfaces using the scanning electron microscopy (SEM) method.In quasi-static conditions of loading, the material reached its capacity due to the formation of shear bands, that concerned all three tested compression directions. In dynamics, the failure took place by shearing followed by delamination. In case of dynamic loading in the direction perpendicular to fibers, the observations made by SEM showed that the failure of the composite had a fragile nature.

Keywords:
Woven composite, Dynamic behaviour, Dynamic fracture, Split Hopkinson Pressure Bar, Failure energy, Anisotropy, Strain rate

8.Piotrowski T., Glinicka J., Glinicki M.A., Prochoń P., Influence of gadolinium oxide and ulexite on cement hydration and technical properties of mortars for neutron radiation shielding purposes, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2018.11.076, Vol.195, pp.583-589, 2019
Piotrowski T., Glinicka J., Glinicki M.A., Prochoń P., Influence of gadolinium oxide and ulexite on cement hydration and technical properties of mortars for neutron radiation shielding purposes, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2018.11.076, Vol.195, pp.583-589, 2019

Abstract:
Gadolinium oxide (Gd2O3) is a potentially effective mineral additive that improves neutron shielding properties of cement based composites. The paper presents the influence of Gd2O3 and ulexite (a boron compound) on Portland cement hydration evaluated by isothermal calorimetry measurements and strength. The progress of hydration was investigated on mortar specimens at water to cement ratio w/c = 0.5 and sand/cement ratio 0.75. The addition of Gd2O3 generates a slight retardation of cement hydration, however it accelerates aluminate activity at the same time. The hydration of cement was completely hindered for mortars containing a substantial content of ulexite. The strength test results show that addition of Gd2O3 to Portland cement mortar mix caused a decrease of early age (3 days) flexural and compressive strength. The optimum content of Gd2O3 in respect to the long term compressive strength and the hydration kinetics was 5% in relation to the mass of cement. Good long term strength was also obtained for specimens with 3% of ulexite.

Keywords:
Gadolinium oxide generates a slight retardation of cement hydration, Gadolinium oxide increases hydration intensity by aluminate activity acceleration, Gadolinium oxide optimum content is 5% in relation to the mass of cement, A substantial content of ulexite hinders almost completely the cement hydration, Good long term performance were obtained also for specimens with 3% of ulexite

9.Jaskulski R., Glinicki M.A., Ranachowski Z., Kubissa W., Organic phosphorus compounds as heat release regulators in hardening shielding concrete, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2019.03.081, Vol.209, pp.167-175, 2019
Jaskulski R., Glinicki M.A., Ranachowski Z., Kubissa W., Organic phosphorus compounds as heat release regulators in hardening shielding concrete, CONSTRUCTION AND BUILDING MATERIALS, ISSN: 0950-0618, DOI: 10.1016/j.conbuildmat.2019.03.081, Vol.209, pp.167-175, 2019

Abstract:
The paper presents the results of the study of the influence of the addition of retarding superplasticising admixture based on triisobutyl phosphate and modified phosphonates on the amount of heat generated by hardening shielding concrete. A four-point measurement of the heat generated during the hardening of concrete with an admixture dose of 0, 0.5, 1.0 and 2.0% by weight of the cement was made and the concurrent measurement of the heat released by the hardening cement paste was measured with an isothermal calorimeter. Based on the results from the calorimeter, the effect of the admixture on the temperature field in the hardening concrete mass elements was simulated for different aggregates. The results indicate that the admixture clearly lowers the temperature gradient in hardening mass concrete. In the simulations, the most clear effect was achieved in the case of concrete with barite aggregate, where the gradient value was reduced from 10C/m to 8C/m for an admixture content equal to 2.0%.  2019 Elsevier Ltd. All rights reserved.

Keywords:
Temperature gradient, Heat release, Shielding concrete, Mass concrete, Fresh concrete, Phosphorus compounds

10.Madan N., Rojek J., Nosewicz S., Convergence and stability analysis of the deformable discrete element method, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.6014, Vol.118, No.6, pp.320-344, 2019
Madan N., Rojek J., Nosewicz S., Convergence and stability analysis of the deformable discrete element method, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.6014, Vol.118, No.6, pp.320-344, 2019

Abstract:
This work investigates numerical properties of the algorithm of the discrete element method employing deformable circular discs presented in an earlier authors' publication. The new formulation, called the deformable discrete element method (DDEM) enhances the standard discrete element method (DEM) by introducing an additional (global) deformation mode caused by the stresses in the particles induced by the contact forces. An accurate computation of the contact forces would require an iterative solution of the implicit relationship between the contact forces and particle displacements. In order to preserve efficiency of the DEM, the new formulation has been adapted to the explicit time integration. It has been shown that the explicit DDEM algorithm is conditionally stable and there are two restrictions on its stability. Except for the limitation of the time step as in the standard DEM, the stability in the DDEM is governed by the convergence criterion of the iterative solution of the contact forces. The convergence and stability limits have been determined analytically and numerically for selected regular and irregular configurations. It has also been found out that the critical time step in DDEM remains unchanged with respect to standard DEM.

Keywords:
discrete element method; deformable particles; iterative solution; convergence criterion;explicit scheme; stability

11.Jaskulski R., Glinicki M.A., Kubissa W., Dąbrowski M., Application of a non-stationary method in determination of the thermal properties of radiation shielding concrete with heavy and hydrous aggregate, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, ISSN: 0017-9310, DOI: 10.1016/j.ijheatmasstransfer.2018.07.050, Vol.130, pp.882-892, 2019
Jaskulski R., Glinicki M.A., Kubissa W., Dąbrowski M., Application of a non-stationary method in determination of the thermal properties of radiation shielding concrete with heavy and hydrous aggregate, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, ISSN: 0017-9310, DOI: 10.1016/j.ijheatmasstransfer.2018.07.050, Vol.130, pp.882-892, 2019

Abstract:
Results of measurements of the specific heat and the thermal conductivity of concrete with blended special aggregate for neutron and gamma radiation shielding are presented. Experimental tests were performed on concrete with heavyweight aggregate (magnetite, barite), hydrogen-bearing aggregate (serpentine) and amphibolite aggregate. The thermal properties of concrete were determined using a nonstationary method. The highest specific heat was found for concrete with serpentine aggregate. Simple models for predicting the specific heat and the thermal conductivity on the basis of concrete mix design were evaluated to include the blends of heavyweight and hydrogen-bearing aggregates. The thermal conductivity of concrete was found to be linearly dependent on the concrete density in the range from 2200 to 3500 kg/m3. Its increase due to water saturation of concrete was not dependent on the open porosity of concrete. It was found that the specific heat can be fairly well predicted using the rule of mixtures formula. The thermal conductivity of concrete can be approximately predicted using a parallel model in the case of water-saturated concrete. The thermal conductivity prediction for dry concrete is also discussed.

Keywords:
Blended aggregate, Concrete mix design, Density, Non-stationary method, Open porosity, Thermal properties, Thermal conductivity, Specific heat, Radiation shielding

12.Ryś M., Egner H., Energy equivalence based constitutive model of austenitic stainless steel at cryogenic temperatures, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2018.12.028, Vol.164, pp.52-65, 2019
Ryś M., Egner H., Energy equivalence based constitutive model of austenitic stainless steel at cryogenic temperatures, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2018.12.028, Vol.164, pp.52-65, 2019

Abstract:
In the present work the constitutive model of 316L and 304 stainless steel subjected to mechanical loading at cryogenic temperatures is derived. Three main coupled dissipative phenomena taking place in the material: plastic flow, plastic strain-induced transformation from the primary phase (γ) to the secondary phase (α′), and evolution of micro-damage are considered using a thermodynamically consistent framework. The approach based on total energy equivalence, originally developed for damaged materials, is here extended to modelling not only damage but also phase transformation, in a consistent manner. The proposed model is implemented numerically and validated by means of parametric studies, and by comparison with the experimental results. Very good qualitative and quantitative results are obtained.

Keywords:
Constitutive modelling, Plasticity, Damage, Phase transformation, Cryogenic temperatures

13.Sadowski Ł., Piechówka-Mielnik M., Widziszowski T., Gardynik A., Mackiewicz S., Hybrid ultrasonic-neural prediction of the compressive strength of environmentally friendly concrete screeds with high volume of waste quartz mineral dust, Journal of Cleaner Production, ISSN: 0959-6526, DOI: 10.1016/j.jclepro.2018.12.059, Vol.212, pp.727-740, 2019
Sadowski Ł., Piechówka-Mielnik M., Widziszowski T., Gardynik A., Mackiewicz S., Hybrid ultrasonic-neural prediction of the compressive strength of environmentally friendly concrete screeds with high volume of waste quartz mineral dust, Journal of Cleaner Production, ISSN: 0959-6526, DOI: 10.1016/j.jclepro.2018.12.059, Vol.212, pp.727-740, 2019

Abstract:
The article presents the hybrid ultrasonic-neural assessment of the compressive strength of low-strength concrete screeds modified using high volume of mineral dusts sourced from industrial wastes. Quartz and quartz-feldspar dusts were selected to replace up to the 60% of the cement mass. The principal aim of this study is to carry out a systematic investigation of the effect of the addition of selected dusts on the compressive strength of such modified concrete screeds. The ultrasonic pulse velocity (UPV) technique was used for this purpose. After UPV analysis, about 13 different compositions were tested after 28 days for their compressive strengths (ranging from about 4 to 16 MPa). The relationship between the ultrasound velocity and compressive strength of the low-strength concrete screeds was found to be not acceptable. Finally, the artificial neural networks (ANNs) were employed to predict the compressive strength based on the composition of the concrete and UPV velocity. The obtained values of linear correlation coefficient (R) equal to 0.93, 0.91 and 0.94 respectively for learning, testing and validation phase were satisfactory for reliable evaluation of the compressive strength of environmentally friendly low-strength concrete screeds modified using high volume of waste quartz mineral dusts

Keywords:
Partial replacement of ordinary cement with waste quartz dusts was studied, The utilization of waste quartz mineral dust in concrete screeds was promising, Hybrid ultrasonic-neural prediction of the compressive strength was presented, Waste quartz mineral dusts can be used in screeds for nonstructural applications, The algorithm Broyden-Fletcher-Goldfarb-Shanno (BFGS) was selected

14.Pręgowska A., Kaplan E., Szczepański J., How Far can Neural Correlations Reduce Uncertainty? Comparison of Information Transmission Rates for Markov and Bernoulli Processes, International Journal of Neural Systems, ISSN: 0129-0657, DOI: 10.1142/S0129065719500035, Vol.29, No.0, pp.1950003-1-13, 2019
Pręgowska A., Kaplan E., Szczepański J., How Far can Neural Correlations Reduce Uncertainty? Comparison of Information Transmission Rates for Markov and Bernoulli Processes, International Journal of Neural Systems, ISSN: 0129-0657, DOI: 10.1142/S0129065719500035, Vol.29, No.0, pp.1950003-1-13, 2019

Abstract:
The nature of neural codes is central to neuroscience. Do neurons encode information through relatively slow changes in the firing rates of individual spikes (rate code) or by the precise timing of every spike (temporal code)? Here we compare the loss of information due to correlations for these two possible neural codes. The essence of Shannon’s definition of information is to combine information with uncertainty: the higher the uncertainty of a given event, the more information is conveyed by that event. Correlations can reduce uncertainty or the amount of information, but by how much? In this paper we address this question by a direct comparison of the information per symbol conveyed by the words coming from a binary Markov source (temporal code) with the information per symbol coming from the corresponding Bernoulli source (uncorrelated, rate code). In a previous paper we found that a crucial role in the relation between information transmission rates (ITRs) and firing rates is played by a parameter s, which is the sum of transition probabilities from the no-spike state to the spike state and vice versa. We found that in this case too a crucial role is played by the same parameter s. We calculated the maximal and minimal bounds of the quotient of ITRs for these sources. Next, making use of the entropy grouping axiom, we determined the loss of information in a Markov source compared with the information in the corresponding Bernoulli source for a given word length. Our results show that in the case of correlated signals the loss of information is relatively small, and thus temporal codes, which are more energetically efficient, can replace rate codes effectively. These results were confirmed by experiments.

Keywords:
Shannon information theory, information source, information transmission rate, firing rate, neural coding

15.Grabowski F., Czyż P., Kochańczyk M., Lipniacki T., Limits to the rate of information transmission through the MAPK pathway, JOURNAL OF THE ROYAL SOCIETY INTERFACE, ISSN: 1742-5689, DOI: 10.1098/rsif.2018.0792, Vol.16, No.152, pp.20180792-1-10, 2019
Grabowski F., Czyż P., Kochańczyk M., Lipniacki T., Limits to the rate of information transmission through the MAPK pathway, JOURNAL OF THE ROYAL SOCIETY INTERFACE, ISSN: 1742-5689, DOI: 10.1098/rsif.2018.0792, Vol.16, No.152, pp.20180792-1-10, 2019

Abstract:
Two important signalling pathways of NF-κB and ERK transmit merely 1 bit of information about the level of extracellular stimulation. It is thus unclear how such systems can coordinate complex cell responses to external cues. We analyse information transmission in the MAPK/ERK pathway that converts both constant and pulsatile EGF stimulation into pulses of ERK activity. Based on an experimentally verified computational model, we demonstrate that, when input consists of sequences of EGF pulses, transmitted information increases nearly linearly with time. Thus, pulse-interval transcoding allows more information to be relayed than the amplitude–amplitude transcoding considered previously for the ERK and NF-κB pathways. Moreover, the information channel capacity C, or simply bitrate, is not limited by the bandwidth B = 1/τ, where τ ≈ 1 h is the relaxation time. Specifically, when the input is provided in the form of sequences of short binary EGF pulses separated by intervals that are multiples of τ/n (but not shorter than τ), then for n = 2, C ≈ 1.39 bit/h; and for n = 4, C ≈ 1.86 bit/h. The capability to respond to random sequences of EGF pulses enables cells to propagate spontaneous ERK activity waves across tissue.

Keywords:
cellular signal transduction, pulsatile stimulation, pulse-interval transcoding, bandwidth, representation problem

16.Zaremba D., Błoński S., Marijnissen M.J., Korczyk P.M., Fixing the direction of droplets in a bifurcating microfluidic junction, MICROFLUIDICS AND NANOFLUIDICS, ISSN: 1613-4982, DOI: 10.1007/s10404-019-2218-x, Vol.23, pp.55-1-18, 2019
Zaremba D., Błoński S., Marijnissen M.J., Korczyk P.M., Fixing the direction of droplets in a bifurcating microfluidic junction, MICROFLUIDICS AND NANOFLUIDICS, ISSN: 1613-4982, DOI: 10.1007/s10404-019-2218-x, Vol.23, pp.55-1-18, 2019

Abstract:
We present a novel type of microfluidic bifurcating junctions which fixes the droplet’s route. Unlike in regular junctions, where a droplet chooses one of two outputs depending on the (often instantaneous) flow distribution, our modifications direct droplets only to one preferred outlet. As we show, this solution works properly regardless of the variations of flow distribution in a wide range of its amplitude. Such modified junctions allow for the encoding of the droplet’s traffic in the geometry of the device. We compare in a series of experiments different junctions having channels of uniform square cross section. Our observations revealed that a small, local modification of the junction in the form of an additional shallow slit imposes a significant consequence for the flow of droplets at an entire microfluidic network’s scale. Another interesting and helpful feature of these new junctions is that they keep the integrity of long droplets, unlike regular junctions, which tend to split long droplets. Our experimental investigations revealed a complex transformation of the long droplet during its transfer through the modified junction. We show that this transformation resembles the Baker’s transform and can be used for the enhancement of mixing inside the droplets. Finally, we show two examples of microfluidic devices where the deterministic character of these modified junctions is utilized to obtain new, non-trivial functionalities. This approach can be used for the engineering of microfluidic devices with embedded procedures replacing active elements like valves or magnetic/electric fields.

Keywords:
Droplet, Microfluidics, Two-phase, Manipulations

17.Chmielewski M., Nosewicz S., Wyszkowska E., Kurpaska Ł., Strojny-Nędza A., Piątkowska A., Bazarnik P., Pietrzak K., Analysis of the micromechanical properties of copper-silicon carbide composites using nanoindentation measurements, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2019.01.257, Vol.45, No.7A, pp.9164-9173, 2019
Chmielewski M., Nosewicz S., Wyszkowska E., Kurpaska Ł., Strojny-Nędza A., Piątkowska A., Bazarnik P., Pietrzak K., Analysis of the micromechanical properties of copper-silicon carbide composites using nanoindentation measurements, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2019.01.257, Vol.45, No.7A, pp.9164-9173, 2019

Abstract:
The study presents a detailed analysis of the impact of the coating type of silicon carbide particles and its share by volume on the microstructure and micromechanical properties of Cu-SiC composites. In order to protect the carbide from decomposition during the manufacturing of the composites, the surface of SiC was modified via a plasma vapour deposition technique with a layer of metals (W, Cr, Ti and Ni). Composites with a variable share of the ceramic phase (10–50 %vol.) were obtained at a temperature of 950 °C using spark plasma sintering. An analysis of the structures of the composites, especially in the metal-ceramic boundary region, was conducted with the use of scanning and transmission electron microscopy. The mechanical properties of the composites in the Cu-interface-SiC system were studied via a nanoindentation technique. The comparison of the results of hardness and Young's modulus studies were completed in relation to the actual structures of the materials, which in turn made it possible to determine the impact of the interfacial structure on the global properties of the composite materials.

Keywords:
Copper-silicon carbide composites; Nanoindentation; SPS; Interface study

18.Li Z., Qu H., Chen F., Wang Y., Tan Z., Kopeć M., Wang K., Zheng K., Deformation Behavior and Microstructural Evolution during Hot Stamping of TA15 Sheets: Experimentation and Modelling, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12020223, Vol.12, No.2-223, pp.1-14, 2019
Li Z., Qu H., Chen F., Wang Y., Tan Z., Kopeć M., Wang K., Zheng K., Deformation Behavior and Microstructural Evolution during Hot Stamping of TA15 Sheets: Experimentation and Modelling, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12020223, Vol.12, No.2-223, pp.1-14, 2019

Abstract:
Near- α titanium alloys have extensive applications in high temperature structural components of aircrafts. To manufacture complex-shaped titanium alloy panel parts with desired microstructure and good properties, an innovative low-cost hot stamping process for titanium alloy was studied in this paper. Firstly, a series of hot tensile tests and Scanning Electron Microscope (SEM) observations were performed to investigate hot deformation characteristics and identify typical microstructural evolutions. The optimal forming temperature range is determined to be from 750 °C to 900 °C for hot stamping of TA15. In addition, a unified mechanisms-based material model for TA15 titanium alloy based on the softening mechanisms of recrystallization and damage was established, which enables to precisely predict stress-strain behaviors and potentially to be implemented into Finite Element (FE) simulations for designing the reasonable processing window of structural parts for the aerospace industry

Keywords:
TA15, hot stamping, phase evolution, deformation, modelling

19.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete Element Modeling of Intermetallic Matrix Composite Manufacturing by Powder Metallurgy, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12020281, Vol.12, No.281, pp.1-18, 2019
Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete Element Modeling of Intermetallic Matrix Composite Manufacturing by Powder Metallurgy, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12020281, Vol.12, No.281, pp.1-18, 2019

Abstract:
This paper presents a numerical and experimental analysis of manufacturing of intermetallic ceramic composites by powder metallurgy techniques. The scope of the paper includes the formulation and development of an original numerical model of powder metallurgy of two-phase material within the framework of the discrete element method, simulations of powder metallurgy processes for different combinations of process parameters, and a verification of the numerical model based on own experimental results. Intermetallic-based composite NiAl–Al2O3 has been selected as representative material for experimental and numerical studies in this investigation. Special emphasis was given to the interactions between the intermetallic and ceramic particles by formulating the special model for adhesive contact bond. In order to properly represent a real microstructure of a two-phase sintered body, a discrete element specimen was generated using a special algorithm. Numerical validation showed the correct numerical representation of a sintered two-phase composite specimen. Finally, micromechanical analysis was performed to explain the macroscopic behavior of the sintered sample. The evolution of the coordination number, a number of equilibrium contacts, and the distribution of the cohesive neck size with respect to time are presented.

Keywords:
powder metallurgy; sintering; discrete element method; modeling; intermetallic matrix composites

20.Ranachowski Z., Ranachowski P., Dębowski T., Gorzelańczyk T., Schabowicz K., Investigation of Structural Degradation of Fiber Cement Boards Due to Thermal Impact, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12060944, Vol.12, No.944, pp.1-14, 2019
Ranachowski Z., Ranachowski P., Dębowski T., Gorzelańczyk T., Schabowicz K., Investigation of Structural Degradation of Fiber Cement Boards Due to Thermal Impact, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12060944, Vol.12, No.944, pp.1-14, 2019

Abstract:
The aim of the present study was to investigate the degradation of the microstructure and mechanical properties of fiber cement board (FCB), which was exposed to environmental hazards, resulting in thermal impact on the microstructure of the board. The process of structural degradation was conducted under laboratory conditions by storing the FCB specimens in a dry, electric oven for 3 h at a temperature of 230 °C. Five sets of specimens, that differed in cement and fiber content, were tested. Due to the applied heating procedure, the process of carbonization and resulting embrittlement of the fibers was observed. The fiber reinforcement morphology and the mechanical properties of the investigated compositions were identified both before, and after, their carbonization. Visual light and scanning electron microscopy, X-ray micro tomography, flexural strength, and work of flexural test Wf measurements were used. A dedicated instrumentation set was prepared to determine the ultrasound testing (UT) longitudinal wave velocity cL in all tested sets of specimens. The UT wave velocity cL loss was observed in all cases of thermal treatment; however, that loss varied from 2% to 20%, depending on the FCB composition. The results obtained suggest a possible application of the UT method for an on-site assessment of the degradation processes occurring in fiber cement boards.

Keywords:
cement-based composites, fiber cement boards, durability, ultrasound measurements

21.Dunić V., Pieczyska E.A., Kowalewski Z.L., Matsui R., Slavković R., Experimental and Numerical Investigation of Mechanical and Thermal Effects in TiNi SMA during Transformation-Induced Creep Phenomena, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12060883, Vol.12(6), No.883, pp.1-13, 2019
Dunić V., Pieczyska E.A., Kowalewski Z.L., Matsui R., Slavković R., Experimental and Numerical Investigation of Mechanical and Thermal Effects in TiNi SMA during Transformation-Induced Creep Phenomena, Materials, ISSN: 1996-1944, DOI: 10.3390/ma12060883, Vol.12(6), No.883, pp.1-13, 2019

Abstract:
The paper presents experimental and numerical results of the TiNi shape memory alloy (SMA) subjected to a modified program of force-controlled tensile loading. The time-dependent development of transformation strain under the constant-force conditions was investigated to describe transformation-induced creep phenomena. (2) Mechanical characteristics of the TiNi SMA were derived using a testing machine, whereas the SMA temperature changes accompanying its deformation were obtained in a contactless manner with an infrared camera. A 3D coupled thermo-mechanical numerical analysis, realized in a partitioned approach, was applied to describe the SMA mechanical and thermal responses. (3) The stress and related temperature changes demonstrated how the transformation-induced creep process started and evolved at various stages of the SMA loading. The proposed model reproduced the stress, strain and temperature changes obtained during the experiment well; the latent heat production is in correlation with the amount of the martensitic volume fraction. (4) It was demonstrated how the transformation-induced creep process occurring in the SMA under such conditions was involved in thermo-mechanical couplings and the related temperature changes.

Keywords:
TiNi shape memory alloy, phase transformation-induced creep, martensitic transformation, temperature change, thermomechanical couplings, infrared camera, thermo-mechanical coupled numerical analysis

22.Poma Bernaola A., Guzman V.H., Li M.S., Theodorakis P.E., Mechanical and thermodynamic properties of Aβ42, Aβ40, and α-synuclein fibrils: a coarse-grained method to complement experimental studies, Beilstein Journal of Nanotechnology, ISSN: 2190-4286, DOI: 10.3762/bjnano.10.51, Vol.10, pp.500-513, 2019
Poma Bernaola A., Guzman V.H., Li M.S., Theodorakis P.E., Mechanical and thermodynamic properties of Aβ42, Aβ40, and α-synuclein fibrils: a coarse-grained method to complement experimental studies, Beilstein Journal of Nanotechnology, ISSN: 2190-4286, DOI: 10.3762/bjnano.10.51, Vol.10, pp.500-513, 2019

Abstract:
We perform molecular dynamics simulation on several relevant biological fibrils associated with neurodegenerative diseases such as Aβ40, Aβ42, and α-synuclein systems to obtain a molecular understanding and interpretation of nanomechanical characterization experiments. The computational method is versatile and addresses a new subarea within the mechanical characterization of heterogeneous soft materials. We investigate both the elastic and thermodynamic properties of the biological fibrils in order to substantiate experimental nanomechanical characterization techniques that are quickly developing and reaching dynamic imaging with video rate capabilities. The computational method qualitatively reproduces results of experiments with biological fibrils, validating its use in extrapolation to macroscopic material properties. Our computational techniques can be used for the co-design of new experiments aiming to unveil nanomechanical properties of biological fibrils from a point of view of molecular understanding. Our approach allows a comparison of diverse elastic properties based on different deformations , i.e., tensile (YL), shear (S), and indentation (YT) deformation. From our analysis, we find a significant elastic anisotropy between axial and transverse directions (i.e., YT > YL) for all systems. Interestingly, our results indicate a higher mechanostability of Aβ42 fibrils compared to Aβ40, suggesting a significant correlation between mechanical stability and aggregation propensity (rate) in amyloid systems. That is, the higher the mechanical stability the faster the fibril formation. Finally, we find that α-synuclein fibrils are thermally less stable than β-amyloid fibrils. We anticipate that our molecular-level analysis of the mechanical response under different deformation conditions for the range of fibrils considered here will provide significant insights for the experimental observations.

Keywords:
Alzheimer disease, Parkinson disease, β-amyloid, α-synuclein, molecular dynamics, AFM, indentation, elasticity, protein, fibrils, assemblies, soft matter, Young modulus

23.Yiu B.Y.S., Walczak M., Lewandowski M., Yu A.C.H., Live Ultrasound Color Encoded Speckle Imaging Platform for Real-Time Complex Flow Visualization In Vivo, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2019.2892731, pp.1-13, 2019
Yiu B.Y.S., Walczak M., Lewandowski M., Yu A.C.H., Live Ultrasound Color Encoded Speckle Imaging Platform for Real-Time Complex Flow Visualization In Vivo, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2019.2892731, pp.1-13, 2019

Abstract:
Complex flow patterns are prevalent in the vasculature, but they are difficult to image non-invasively in real-time. This paper presents the first real-time scanning platform for a high frame rate ultrasound technique called color encoded speckle imaging (CESI) and its use in visualizing arterial flow dynamics in-vivo. CESI works by simultaneously rendering flow speckles and color-coded flow velocity estimates on a time-resolved basis. Its live implementation was achieved by integrating a 192-channel programmable ultrasound front-end module, a 4.8 GB/s capacity data streaming link, and a series of computing kernels implemented on the graphical processing unit (GPU) for beamforming and Doppler processing. A slow-motion replay mode was also included to offer coherent visualization of CESI frames acquired at high frame rate (3,000 fps in our experiments). The live CESI scanning platform was found to be effective in facilitating real-time image guidance (at least 20 fps for live video display with 55 fps GPU processing throughout). In vivo pilot trials also showed that live CESI, when running in replay mode, can temporally resolve triphasic flow at the brachial bifurcation and can reveal flow dynamics in the brachial vein during a fist-clenching maneuver. Overall, live CESI has potential for use in routine investigations in-vivo that seek to identify complex flow dynamics in real-time and relate these dynamics to vascular physiology.

Keywords:
High frame rate ultrasound, Color encoded speckle imaging, Live scanning platform, Graphical processing units, In-vivo studies, Complex flow visualization

24.Kucharski S., Woźniacka S., Size Effect in Single Crystal Copper Examined with Spherical Indenters, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-019-05160-w, pp.1-16, 2019
Kucharski S., Woźniacka S., Size Effect in Single Crystal Copper Examined with Spherical Indenters, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-019-05160-w, pp.1-16, 2019

Abstract:
The increasing hardness with decreasing penetration depth, referred to as indentation size effect (ISE) was previously investigated experimentally and theoretically by many researchers, however the mechanisms responsible for ISE are still being discussed. Generally, ISE is related to the density of geometrically necessary dislocation stored within a small volume beneath the indenter tip. In this study ISE is investigated experimentally in a single crystal copper using spherical indenter tips of different radii. Some new aspects of ISE are shown: a qualitative change of shape of residual impression (pile-up/sink-in pattern) when tip radius or load is modified, an increase of maximum pop-in load with decrease of tip radius as well as the well-known increase of hardness when tip radius decreases are analyzed. As we observe a difference of the residual imprint morphology which depends on tip radius and load, we apply two methods of hardness estimation: true hardness and nominal hardness. The former is determined on the basis of direct measurement of the contact area while accounting for a specific pile-up pattern, while the latter is determined by measuring the contact area using residual penetration depth. We show that hardness–tip radius relationship has a linear form for the nominal hardness and bilinear form for the true hardness.

25.Krajewski M., Węglewski W., Bochenek K., Wysmołek A., Basista M., Optical measurements of thermal residual stresses in alumina reinforced with chromium, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.5083115, Vol.125, No.135104, pp.135104-1-135104-10, 2019
Krajewski M., Węglewski W., Bochenek K., Wysmołek A., Basista M., Optical measurements of thermal residual stresses in alumina reinforced with chromium, JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.5083115, Vol.125, No.135104, pp.135104-1-135104-10, 2019

Abstract:
This work describes optical measurements of processing-induced thermal residual stresses in an alumina matrix reinforced with chromium particles. This ceramic-metal composite is manufactured by the powder metallurgy method comprising powder mixing in a planetary ball mill and consolidation by hot pressing. Two different chromium powders (5 μm and 45 μm mean particle size) are used, while the average
alumina particle size is kept constant (1 μm). The residual stresses in aluminum oxide are determined by applying two optical methods: photoluminescence piezo-spectroscopy (PLPS) and Raman spectroscopy (RS). Both experimental techniques reveal a chromium size effect in the residual stress measurements. When the fine chromium powder (5 μm) is used, the average residual stress in the ceramic phase is
tensile (unusual effect), whereas for the coarser chromium powder (45 μm) it becomes compressive. The PLPS measurements of the hydrostatic residual stress component in the ceramic phase yield the values of 0.290 and −0.130 GPa for samples with 5 μm and 45 μm chromium powders, respectively. In the RS experiments, the corresponding stress component in the alumina equals 0.351 GPa for the composite with 5 μm chromium and −0.158 GPa for that with 45 μm chromium powder. These values indicate that the residual stress in the alumina reinforced with 5 μm chromium is approximately twice higher than that in the alumina reinforced with 45 μm chromium. Finally, the validity of the results obtained with the optical techniques is confirmed by the neutron diffraction measurements.

26.Lengiewicz J., Hołobut P., Efficient collective shape shifting and locomotion of massively-modular robotic structures, Autonomous Robots, ISSN: 0929-5593, DOI: 10.1007/s10514-018-9709-6, Vol.43, No.1, pp.97-122, 2019
Lengiewicz J., Hołobut P., Efficient collective shape shifting and locomotion of massively-modular robotic structures, Autonomous Robots, ISSN: 0929-5593, DOI: 10.1007/s10514-018-9709-6, Vol.43, No.1, pp.97-122, 2019

Abstract:
We propose a methodology of planning effective shape shifting and locomotion of large-ensemble modular robots based on a cubic lattice. The modules are divided into two groups: fixed ones, that build a rigid porous frame, and mobile ones, that flow through the frame.Mobile modules which flow out of the structure attach to the frame, advancing its boundary. Conversely, a deficiency of mobile modules in other parts of the boundary is corrected by decomposition of the frame. Inside the structure, appropriate module flow is arranged to transport the modules in a desired direction, which is planned by a special distributed version of a maximum flow search algorithm. The method engages a volume of modules during reconfiguration, which is more efficient than common surface-flow approaches. Also, the proposed interpretation as a flow in porous media with moving boundaries seems particularly suitable for further development of more advanced global reconfiguration scenarios. The theoretical efficiency of the method is assessed, and then partially verified by a series of simulations. The method can be possibly also applied to a wider class of modular robots, not necessarily cubic-lattice-based.

Keywords:
Modular robots, Self-reconfiguration, Maximum flow search, Programmable matter, Distributed algorithms

27.Ekiel-Jeżewska M.L., Adamczyk Z., Bławzdziewicz J., Streaming Current and Effective ζ-Potential for Particle-Covered Surfaces with Random Particle Distributions, The Journal of Physical Chemistry C, ISSN: 1932-7447, DOI: 10.1021/acs.jpcc.8b10068, Vol.123, No.6, pp.3517-3531, 2019
Ekiel-Jeżewska M.L., Adamczyk Z., Bławzdziewicz J., Streaming Current and Effective ζ-Potential for Particle-Covered Surfaces with Random Particle Distributions, The Journal of Physical Chemistry C, ISSN: 1932-7447, DOI: 10.1021/acs.jpcc.8b10068, Vol.123, No.6, pp.3517-3531, 2019

Abstract:
A detailed theoretical and experimental study is presented concerning the streaming current and the derivative effective ζ-potential for a planar surface covered by a monolayer of adsorbed particles. Precise simulation results are obtained for the equilibrium and random-sequential-adsorption (RSA) distributions of monodisperse spherical particles interacting via the excluded-volume potential. The streaming current is calculated in the thin-double-layer regime for all physically accessible particle area fractions. The results are expressed as a linear combination of the interface and particle contributions DI and DP weighted by the interface and particle ζ-potentials ζI and ζP. We find that in the area-fraction regime where both particle distributions exist, the equilibrium and RSA results for the streaming current are nearly indistinguishable. Our numerical data show that DI exponentially decays to zero when the particle area fraction θ is increased, whereas DP exponentially tends to a linear behavior. The results are described (with the accuracy better than 1.5% of the maximal value) by the exponential and linear plus exponential approximations, with only one fitting parameter. The numerical and theoretical predictions are in agreement with experimental data obtained for a wide range of ζ-potentials of the interface and the particles. Results obtained for a rough surface with spherical asperities indicate that the roughness can reduce the effective ζ-potential (as evaluated from the streaming current) by more than 25%; this prediction is also confirmed by experiments.

28.Jozwik P., Kopeć M., Polkowski W., Bojar Z., Dynamic deformation tests of ni3al based intermetallic alloy by using the split Hopkinson pressure bar technique, Journal of Mining and Metallurgy, Section B: Metallurgy, ISSN: 1450-5339, DOI: 10.2298/JMMB181113014J, Vol.55, No.1, pp.129-134, 2019
Jozwik P., Kopeć M., Polkowski W., Bojar Z., Dynamic deformation tests of ni3al based intermetallic alloy by using the split Hopkinson pressure bar technique, Journal of Mining and Metallurgy, Section B: Metallurgy, ISSN: 1450-5339, DOI: 10.2298/JMMB181113014J, Vol.55, No.1, pp.129-134, 2019

Abstract:
In this work, the Ni3Al-based intermetallic alloy was subjected to room temperature dynamic plastic deformation tests by using a split Hopkinson pressure bar technique. The dynamic compression processes were carried out at strain rates in the range of =(1.9×102 ÷ 1×104 s-1). A strong impact of applied deformation conditions on microstructure and mechanical properties evolution in the examined Ni3Al intermetallic, was documented. Generally, very high maximum compressive stress values were obtained, reaching 5500 MPa for the sample deformed at the highest strain rate (i.e. =1×104 s-1). The results of performed SEM/EBSD evaluation point towards an occurrence of dynamic recovery and recrystallization phenomena in Ni3Al samples deformed at high strain rates.

Keywords:
Ni3Al-based alloy, Split Hopkinson pressure bar, SEM/EBSD analysis

29.Pisarski D., Myśliński A., Suboptimal distributed state-feedback control of semi-active vibrating systems, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2018.12.009, Vol.443, pp.637-651, 2019
Pisarski D., Myśliński A., Suboptimal distributed state-feedback control of semi-active vibrating systems, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2018.12.009, Vol.443, pp.637-651, 2019

Abstract:
A novel semi-active control method for mitigating structural vibration is studied. The method relies on distributed state information patterns and the solution to a suboptimal control problem that aims at replicating the switched structures of the optimal open-loop stabilizing controls. The optimality conditions and the method of solution of the suboptimal problem are discussed. The performance of this method is examined by means of numerical experiments performed for a double cantilever system equipped with a set of semi-active elastomers with controlled viscoelastic properties. The experiments were carried out for different controller architectures and a series of initial conditions. In terms of the assumed objectives, the proposed distributed control strategy significantly outperforms the passive damping strategies and is competitive with a standard centralized control. The proposed approach is general to a class of bilinear control systems concerned with smart structural elements. The practical aspects of the designed distributed controller are highlighted.

Keywords:
distributed control, optimal control, bilinear system, stabilization, semi-active structure

30.Meissner M., Wiśniewski K., Influence of room modes on low-frequency transients: Theoretical modeling and numerical predictions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2019.02.012, Vol.448, pp.19-33, 2019
Meissner M., Wiśniewski K., Influence of room modes on low-frequency transients: Theoretical modeling and numerical predictions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2019.02.012, Vol.448, pp.19-33, 2019

Abstract:
In the low-frequency range, a sound reproduction in enclosures is strongly influenced by excited room modes. While the spectral impact of acoustic modes on a room response is well recognized, there is no sufficient knowledge on how these modes affects transients. In the paper this issue has been examined theoretically and numerically for a room excited by a tone burst by using a modal expansion method supported by a computer implementation. To quantify a temporal accuracy of a sound reproduction, the new metrics referred to as the tone burst reproduction error was introduced. The basis for determining this quantity was a deviation between the tone burst amplitude and the amplitude of a sound pressure computed via the Hilbert transform. A numerical simulation was performed for an irregularly shaped enclosure having a form of two-room coupled system. Calculation results have proved that a high inaccuracy of a tone burst reproduction occurs at receiving points corresponding to sharp dips in a distribution of the steady-state sound pressure level. This is because in these points an amplitude of transient sound is much bigger than a tone burst amplitude. It was discovered that strong narrow peaks in the tone burst reproduction error are located at centers of vortices in the active sound intensity vector field. An influence of a sound damping in a room on a reproduction of a tone burst was also examined and it was found that a substantial increase in a wall sound absorption does not significantly improves a tone burst reproduction because it does not eliminate sharp dips in a distribution of the steady-state sound pressure level.

Keywords:
room acoustics, room modes, transients, tone burst, discrete Hilbert transform, sound intensity vector field

31.Faraj R., Graczykowski C., Hybrid Prediction Control for self-adaptive fluid-based shock-absorbers, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2019.02.022, Vol.449, pp.427-446, 2019
Faraj R., Graczykowski C., Hybrid Prediction Control for self-adaptive fluid-based shock-absorbers, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2019.02.022, Vol.449, pp.427-446, 2019

Abstract:
The paper covers detailed discussion on novel control system developed for adaptive fluidbased shock-absorbers serving for mitigation of unknown impact excitations. In order to provide complete independence of the control system from the loading conditions, the Hybrid Prediction Control (HPC) was elaborated. The proposed method is an extension of previously introduced kinematic feedback control which ensures optimal path finding, tracking and path update in case of high disturbance or sudden change of loading conditions. Implementation of the presented control system allows to obtain self-adaptive fluid-based absorbers providing robust impact mitigation. In contrast to previously developed methods of Adaptive Impact Absorption, the proposed control strategy does not require prior knowledge of impact excitation or its preliminary identification. The independence of applied control system from parameters of impact loading results in the capability of automatic path correction in the case of disturbance occurrence and readaptation to a number of subsequent impacts. The successful operation of the selfadaptive system is investigated with the use of numerical examples involving doublechamber pneumatic shock-absorber equipped with controllable valve. Efficiency of the HPC is proved by comparison with passive absorber as well as device equipped with adaptive and optimal control modules.

Keywords:
Hybrid Prediction Control, kinematic feedback control, Adaptive Impact Absorption, unknown impact mitigation, self-adaptive system

32.Chrzanowska-Giżyńska J., Denis P., Giżyński M., Kurpaska Ł., Mihailescu I., Ristoscu C., Szymański Z., Mościcki T., Thin WBx and WyTi1−yBx films deposited by combined magnetron sputtering and pulsed laser deposition technique, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2019.02.006, Vol.478, pp.505-513, 2019
Chrzanowska-Giżyńska J., Denis P., Giżyński M., Kurpaska Ł., Mihailescu I., Ristoscu C., Szymański Z., Mościcki T., Thin WBx and WyTi1−yBx films deposited by combined magnetron sputtering and pulsed laser deposition technique, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2019.02.006, Vol.478, pp.505-513, 2019

Abstract:
The coatings of tungsten borides (WBx) and tungsten borides doped with titanium (WyTi1−yBx) were deposited by using combined magnetron sputtering - pulsed laser deposition technique. In the case of WBx coatings, pure tungsten target was evaporated by a laser pulse at 1064 nm wavelength and pure boron target was sputtered by a magnetron. In the case of WyTi1−yBx coatings, the W2B5 target was sputtered by the magnetron and titanium target was evaporated by the laser pulse at 1064 nm wavelength. The content of titanium dopant changed from 1.1 to 5.5 at.%. The microstructure, chemical and phase composition of deposited coatings were investigated by means of Scanning Electron Microscopy, Energy Dispersive X-Ray Spectroscopy, X-Ray Photoelectron Spectroscopy and X-Ray Diffractometry, respectively. The Vickers hardness and Young's modulus were determined by using the nanoindentation test. Nanocrystalline WB coatings with dominant WB2 phase were obtained at a substrate temperature of 520 °C. The coatings were superhard with a hardness of 47–50 GPa and the mean value of surface roughness was <6 nm. The WBx coatings doped with 5.5 at.% Ti had hardness similar to the coatings sputtered by magnetron from W2B5 target.

Keywords:
The superhard WyBx thin films was deposited with hybrid laser-magnetron technology, The MS-PLD method allows for the deposition of ternary borides such as WyTi1−yBx, The MS-PLD method enables to control the chemical and phase composition of films, The deposited films are smooth with hardness above 50 GPa, Crystalline films were deposited only on a substrate kept an elevated temperature

33.Nosewicz S., Rojek J., Wawrzyk K., Kowalczyk P., Maciejewski G., Maździarz M., Multiscale modeling of pressure-assisted sintering, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, DOI: 10.1016/j.commatsci.2018.10.001, Vol.156, pp.385-395, 2019
Nosewicz S., Rojek J., Wawrzyk K., Kowalczyk P., Maciejewski G., Maździarz M., Multiscale modeling of pressure-assisted sintering, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, DOI: 10.1016/j.commatsci.2018.10.001, Vol.156, pp.385-395, 2019

Abstract:
This report presents the modeling of pressure-assisted sintering within the framework of a multiscale approach. Three individual numerical methods have been collectively applied to predict the behavior of a sintering body at three different scales. The appropriate solutions to connect each model/scale have been proposed. Molecular dynamics have been employed to evaluate the grain boundary diffusion coefficient at the atomistic scale. The obtained results of diffusive parameters have been transferred to the micromechanical model of sintering. Here, the discrete element method was used to represent the sintered material properties at the microscopic scale. Micromechanical based results have been validated by own experimental data of material density evolution, indicating the required coincidence. The transfer from micro- to the macroscopic model has been realized by determining the macroscopic viscous moduli from discrete element simulations and subsequently applying them to the continuum model of sintering. The numerical results from finite element simulations at the macroscopic scale have been compared with discrete element ones.

Keywords:
Sintering; Multiscale modeling; Discrete element method; Molecular dynamics; Finite element method

34.Enayati M.S., Neisiany R.E., Sajkiewicz P., Behzad T., Denis P., Pierini F., Effect of nanofiller incorporation on thermomechanical and toughness of poly (vinyl alcohol)-based electrospun nanofibrous bionanocomposites, Theoretical and Applied Fracture Mechanics, ISSN: 0167-8442, DOI: 10.1016/j.tafmec.2018.11.006, Vol.99, pp.44-50, 2019
Enayati M.S., Neisiany R.E., Sajkiewicz P., Behzad T., Denis P., Pierini F., Effect of nanofiller incorporation on thermomechanical and toughness of poly (vinyl alcohol)-based electrospun nanofibrous bionanocomposites, Theoretical and Applied Fracture Mechanics, ISSN: 0167-8442, DOI: 10.1016/j.tafmec.2018.11.006, Vol.99, pp.44-50, 2019

Abstract:
The current work studies the electrospun poly (vinyl alcohol) (PVA) nanofibers and its nanocomposites including nanohydroxy apatite (nHAp) and nHAp/cellulose nanofibers (CNFs), emphasizing the impact of nanofillers on the toughness of nanofibers. PVA nanofibers were incorporated with 10 wt% of nHAp and then various amounts of CNF were added to subsequent PVA/nHAp fibrous nanocomposites. The morphology of nonwoven mats was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). While neat PVA nanofibers were smooth and uniform in thickness, the nanofiller loading resulted in thinner fibers with less uniformity. Furthermore, the thermal properties of the nonwoven network of fibers were characterized employing thermogravimetric analysis (TGA). Although the maximum loss mass temperature of PVA was partially reduced upon addition of nanofillers, the onset of decomposition was not altered. The mechanical characterizations were performed using static tensile and dynamic mechanical analysis (DMA). Compared to neat PVA mats, the tensile test of nanocomposites mats demonstrated the significant increase in Young’s modulus; however, strain at break was dramatically reduced. In addition, the fracture work was assessed from the area under the stress-strain curve, which showed brittleness of fibrous nanocomposites due to the nanofiller incorporation. Field emission SEM (FE-SEM) was employed to scan the fracture surface of stretched fibers. The increase in modulus of electrospun mats was also shown by DMA in frequency mode. In parallel, both tensile test and DMA confirmed the change in fracture of PVA fibers from a tough to brittle mode, due to the nanofiller addition.

Keywords:
Electrospun nanocomposites, Nanofillers, Toughness, Mechanical properties

35.Woźniak M., Chlanda A., Oberbek P., Heljak M., Czarnecka K., Janeta M., John Ł., Binary bioactive glass composite scaffolds for bone tissue engineering—Structure and mechanical properties in micro and nano scale. A preliminary study, Micron, ISSN: 0968-4328, DOI: 10.1016/j.micron.2018.12.006, Vol.119, pp.64-71, 2019
Woźniak M., Chlanda A., Oberbek P., Heljak M., Czarnecka K., Janeta M., John Ł., Binary bioactive glass composite scaffolds for bone tissue engineering—Structure and mechanical properties in micro and nano scale. A preliminary study, Micron, ISSN: 0968-4328, DOI: 10.1016/j.micron.2018.12.006, Vol.119, pp.64-71, 2019

Abstract:
Composite scaffolds of bioactive glass (SiO 2 -CaO) and bioresorbable polyesters: poly- l -lactic acid (PLLA) and polycaprolactone (PCL) were produced by polymer coating of porous foams. Their structure and mechanical properties were investigated in micro and nanoscale, by the means of scanning electron microscopy, PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) atomic force microscopy, micro-computed tomography and contact angle measurements. This is one of the first studies in which the nanomechanical properties (elastic modulus, adhesion) were measured and mapped simultaneously with topography imaging (PF-QNM AFM) for bioactive glass and bioactive glass – polymer coated scaffolds. Our findings show that polymer coated scaffolds had higher average roughness and lower stiffness in comparison to pure bioactive glass scaffolds. Such coating-dependent scaffold properties may promote different cells-scaffold interaction.

Keywords:
Bone tissue engineering, Composite scaffold, Bioactive glass, Mechanical properties

36.Zieliński T.G., Chevillotte F., Deckers E., Sound absorption of plates with micro-slits backed with air cavities: Analytical estimations, numerical calculations and experimental validations, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2018.11.026, Vol.146, pp.261-279, 2019
Zieliński T.G., Chevillotte F., Deckers E., Sound absorption of plates with micro-slits backed with air cavities: Analytical estimations, numerical calculations and experimental validations, APPLIED ACOUSTICS, ISSN: 0003-682X, DOI: 10.1016/j.apacoust.2018.11.026, Vol.146, pp.261-279, 2019

Abstract:
This work discusses many practical and some theoretical aspects concerning modelling and design of plates with micro-slits, involving multi-scale calculations based on microstructure. To this end, useful mathematical reductions are demonstrated, and numerical computations are compared with possible analytical estimations. The numerical and analytical approaches are used to calculate the transport parameters for complex micro-perforated (micro-slotted) plates, which allow to determine the effective properties of the equivalent fluid, so that at the macro-scale level the plate can be treated as a specific layer of acoustic fluid. In that way, the sound absorption of micro-slotted plates backed with air cavities can be determined by solving a multi-layer system of Helmholtz equations. Two such examples are presented in the paper and validated experimentally. The first plate has narrow slits precisely cut out using a traditional technique, while the second plate - with an original micro-perforated pattern - is 3D-printed.

Keywords:
Micro-slotted plates, Micro-perforated plates, Sound absorption, Microstructure-based modelling, 3D-printing

37.Hou J., Wang P., Jing T., Jankowski Ł., Experimental Study for Damage Identification of Storage Tanks by Adding Virtual Masses, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s19020220, Vol.19, No.2, pp.220-1-17, 2019
Hou J., Wang P., Jing T., Jankowski Ł., Experimental Study for Damage Identification of Storage Tanks by Adding Virtual Masses, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s19020220, Vol.19, No.2, pp.220-1-17, 2019

Abstract:
This research proposes a damage identification approach for storage tanks that is based on adding virtual masses. First, the frequency response function of a structure with additional virtual masses is deduced based on the Virtual Distortion Method (VDM). Subsequently, a Finite Element (FE) model of a storage tank is established to verify the proposed method; the relation between the added virtual masses and the sensitivity of the virtual structure is analyzed to determine the optimal mass and the corresponding frequency with the highest sensitivity with respect to potential damages. Thereupon, the damage can be localized and quantified by comparing the damage factors of substructures. Finally, an experimental study is conducted on a storage tank. The results confirm that the proposed method is feasible and practical, and that it can be applied for damage identification of storage tanks.

Keywords:
damage identification, storage tanks, sensitivity analysis, frequency

38.Hou J., Li Z., Zhang Q., Zhou R., Jankowski Ł., Optimal Placement of Virtual Masses for Structural Damage Identification, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s19020340, Vol.19, No.2, pp.340-1-18, 2019
Hou J., Li Z., Zhang Q., Zhou R., Jankowski Ł., Optimal Placement of Virtual Masses for Structural Damage Identification, SENSORS, ISSN: 1424-8220, DOI: 10.3390/s19020340, Vol.19, No.2, pp.340-1-18, 2019

Abstract:
Adding virtual masses to a structure is an efficient way to generate a large number of natural frequencies for damage identification. The influence of a virtual mass can be expressed by Virtual Distortion Method (VDM) using the response measured by a sensor at the involved point. The proper placement of the virtual masses can improve the accuracy of damage identification, therefore the problem of their optimal placement is studied in this paper. Firstly, the damage sensitivity matrix of the structure with added virtual masses is built. The Volumetric Maximum Criterion of the sensitivity matrix is established to ensure the mutual independence of measurement points for the optimization of mass placement. Secondly, a method of sensitivity analysis and error analysis is proposed to determine the values of the virtual masses, and then an improved version of the Particle Swarm Optimization (PSO) algorithm is proposed for placement optimization of the virtual masses. Finally, the optimized placement is used to identify the damage of structures. The effectiveness of the proposed method is verified by a numerical simulation of a simply supported beam structure and a truss structure.

Keywords:
damage identification, sensor optimization, Virtual Distortion Method (VDM), Particle Swarm Optimization (PSO) algorithm, sensitivity

39.Romelczyk-Baishya B., Lumelskyj D., Stępniewska M., Giżyński M., Pakieła Z., The mechanical properties at room and low temperature of p110 steel characterised by means of small punch test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126232, Vol.64, No.1, pp.159-165, 2019
Romelczyk-Baishya B., Lumelskyj D., Stępniewska M., Giżyński M., Pakieła Z., The mechanical properties at room and low temperature of p110 steel characterised by means of small punch test, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126232, Vol.64, No.1, pp.159-165, 2019

Abstract:
In this paper, small punch test (SPT) which is one of miniaturized samples technique, was employed to characterize the mechanical properties of carbon steel P110. The tests were carried out in the range of –175°C to RT. Results obtained for SPT were compared to those calculated for tensile and Charpy impact test. Based on tensile and SPT parameters numerical model was prepared. 8 mm in diameter and 0.8 mm in height (t) discs with and without notch were employed in this research. The specimens had different depth notch (a) in the range of 0.1 to 0.4 mm. It was estimated that α factor for comparison of Tsp and DBTT for carbon steel P110 is 0.55 and the linear relation is DBTT = 0.55TSPT. The numerical model fit with force – deflection curve of SPT. If the factor of notch depth and samples thickness is higher than 0.3 the fracture mode is transformed from ductile to brittle at –150°C.

Keywords:
small punch test, carbon steel P110, small samples, low temperature, mechanical properties

40.Widłaszewski J., Nowak M., Nowak Z., Kurp P., LASER-ASSISTED THERMOMECHANICAL BENDING OF TUBE PROFILES, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126268, Vol.64, No.1, pp.421-430, 2019
Widłaszewski J., Nowak M., Nowak Z., Kurp P., LASER-ASSISTED THERMOMECHANICAL BENDING OF TUBE PROFILES, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126268, Vol.64, No.1, pp.421-430, 2019

Abstract:
The subject of the work is the analysis of thermomechanical bending process of a thin-walled tube made of X5CrNi18-10 stainless steel. The deformation is produced at elevated temperature generated with a laser beam in a specially designed experimental setup. The tube bending process consists of local heating of the tube by a moving laser beam and simultaneous kinematic enforcement of deformation with an actuator and a rotating bending arm. During experimental investigations, the resultant force of the actuator and temperature at the laser spot are recorded. In addition to experimental tests, the bending process of the tube was modelled using the finite element method in the ABAQUS program. For this purpose, the tube deformation process was divided into two sequentially coupled numerical simulations. The first one was the heat transfer analysis for a laser beam moving longitudinally over the tube surface. The second simulation described the process of mechanical bending with the time-varying temperature field obtained in the first simulation. The force and temperature recorded during experiments were used to verify the proposed numerical model. The final stress state and the deformation of the tube after the bending process were analyzed using the numerical solution. The results indicate that the proposed bending method can be successfully used in forming of the thin-walled profiles, in particular, when large bending angles and a small spring-back effect are of interest.

Keywords:
laser forming, laser-assisted bending, numerical modelling

41.Papliński P., Wańkowicz J., Ranachowski P., Ranachowski Z., Investigation of microstructure of ZnO varistors taken from surge arrester counters, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126237, Vol.64, No.1, pp.191-196, 2019
Papliński P., Wańkowicz J., Ranachowski P., Ranachowski Z., Investigation of microstructure of ZnO varistors taken from surge arrester counters, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.24425/amm.2019.126237, Vol.64, No.1, pp.191-196, 2019

Abstract:
The paper presents investigations of microstructure of varistors of damaged surge arrester counters. A similar ZnO varistor, not subjected before to operation, was a point of reference in this research. The results of investigations of the ZnO varistors show an untypical phase composition of their material, which was characterized by unsatisfying homogeneity and cohesion. The degradation processes of varistor material in the subsequent stages were recognized and described. A harmful impact of humidity inside the untight surge arrester counter on its operation and its ZnO varistors was proved. Some conclusions being the result of the operation checking of surge arrester counters were presented too.

Keywords:
surge arrester counter, ZnO varistors, microstructure of ceramics, ceramic material degradation

42.Steifer T., Lewandowski M., Ultrasound tissue characterization based on the Lempel–Ziv complexity with application to breast lesion classification, Biomedical Signal Processing and Control, ISSN: 1746-8094, DOI: 10.1016/j.bspc.2019.02.020, Vol.51, pp.235-242, 2019
Steifer T., Lewandowski M., Ultrasound tissue characterization based on the Lempel–Ziv complexity with application to breast lesion classification, Biomedical Signal Processing and Control, ISSN: 1746-8094, DOI: 10.1016/j.bspc.2019.02.020, Vol.51, pp.235-242, 2019

Abstract:
Building upon the recent successes in the application of information-theoretic concepts (e.g. Shannon entropy) in quantitative ultrasound, the authors propose a novel tissue characterization method based on the Lempel–Ziv complexity. In this procedure, standard ultrasound B-Mode images are mapped onto words over finite alphabets before the corresponding Lempel–Ziv complexity of ultrasound images is calculated. Such complexity metric may be used to differentiate between types of tissues. Here, the method is utilized as a binary classifier for the malignancy of breast lesions. The method is tested on OASBUD – an open-access breast lesions image database. Images of 48 malignant and 48 benign lesions were used – two images for each lesion. The new procedure slightly outperforms the state-of-art classifier based on pixel entropy as measured in the size of area under the receiver operating curve (ROC AUC), which suggests that it may serve as a basis for computer-assisted breast cancer ultrasound diagnosis and possibly in other standard applications of the quantitative ultrasound.

Keywords:
A method based on Lempel–Ziv complexity is proposed for quantitative ultrasound tissue characterization, The method is used to classify breast lesions from an open access ultrasound image database, The method performance is compared with entropy-based classifier as entropy is related theoretically to Lempel–Ziv complexity, The new method achieves 0.87 ROC AUC as compared to 0.84 achieved by the reference method

43.Hou J., Wang S., Zhang Q., Jankowski Ł., An Improved Objective Function for Modal-Based Damage Identification Using Substructural Virtual Distortion Method, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app9050971, Vol.9, No.5, pp.1-17, 2019
Hou J., Wang S., Zhang Q., Jankowski Ł., An Improved Objective Function for Modal-Based Damage Identification Using Substructural Virtual Distortion Method, Applied Sciences, ISSN: 2076-3417, DOI: 10.3390/app9050971, Vol.9, No.5, pp.1-17, 2019

Abstract:
Damage identification based on modal parameters is an important approach in structural health monitoring (SHM). Generally, traditional objective functions used for damage identification minimize the mismatch between measured modal parameters and the parameters obtained from the finite element (FE) model. However, during the optimization process, the repetitive calculation of structural modes is usually time-consuming and inefficient, especially for large-scale structures. In this paper, an improved objective function is proposed based on certain characteristics of the peaks of the frequency response function (FRF). Traditional objective functions contain terms that quantify modal shapes and/or natural frequencies. Here, it is proposed to replace them by the FRF of the FE model, which allows the repeated full modal analysis to be avoided and thus increases the computational efficiency. Moreover, the efficiency is further enhanced by employing the substructural virtual distortion method (SVDM), which allows the frequency response of the FE model of the damaged structure to be quickly computed without the costly re-analysis of the entire damaged structure. Finally, the effectiveness of the proposed method is verified using an eight-story frame structure model under several damage cases. The damage location and extent of each substructure can be identified accurately with 5% white Gaussian noise, and the optimization efficiency is greatly improved compared with the method using a traditional objective function.

Keywords:
structural health monitoring (SHM), damage identification, substructure, virtual distortion method (VDM), frequency response

44.Szmidt T., Pisarski D., Konowrocki R., Awietjan S., Boczkowska A., Adaptive Damping of a Double-Beam Structure Based on Magnetorheological Elastomer, SHOCK AND VIBRATION, ISSN: 1070-9622, DOI: 10.1155/2019/8526179, Vol.2019, No.8526179, pp.1-16, 2019
Szmidt T., Pisarski D., Konowrocki R., Awietjan S., Boczkowska A., Adaptive Damping of a Double-Beam Structure Based on Magnetorheological Elastomer, SHOCK AND VIBRATION, ISSN: 1070-9622, DOI: 10.1155/2019/8526179, Vol.2019, No.8526179, pp.1-16, 2019

Abstract:
A method of vibration reduction based on activation of an MRE block that couples twin cantilever beams at their free ends is investigated. Four types of magnetorheological elastomers have been manufactured, and their rheological properties in a range of magnetic field intensities are established. Free vibrations of several double-beam structures with controllable damping members made of these MREs are investigated, and a method of semiactive control of such structures is proposed. The effects of compression of the elastomers and alignment of the magnets used to activate them are reported. The mathematical modeling of the system is verified experimentally.

Keywords:
adaptive damping, double-Beam structure, magnetorheological elastomer, mathematical modeling, vibration damping

45.Błachowski B., Modal Sensitivity Based Sensor Placement for Damage Identification Under Sparsity Constraint, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.13888, pp.1-14, 2019
Błachowski B., Modal Sensitivity Based Sensor Placement for Damage Identification Under Sparsity Constraint, Periodica Polytechnica Civil Engineering, ISSN: 0553-6626, DOI: 10.3311/PPci.13888, pp.1-14, 2019

Abstract:
The present study deals with a comprehensive approach for damage identification of spatial truss structures. The novelty of the proposed approach consists of a three-level analysis. First, sensitivity of assumed modal characteristics is calculated. Second, natural frequency sensitivity is used to determine hardly identifiable structural parameters and mode shape sensitivity is applied to select damage-sensitive locations of sensors. Third, two sparsity constrained optimization algorithms are tested towards efficient identification of applied damage scenarios. These two algorithms are based on ℓ1-norm minimization and non-negative least square (NNLS) solution. Performances of both proposed algorithms have been compared in two realistic case studies: the first one concerned a three-dimensional truss girder with 61 structural parameters and the second one was devoted to an upper-deck arch bridge composed of 416 steel members.

Keywords:
sensor placement, damage identification, ℓ1-norm minimization, sparsity constrained optimization

46.Dobruch-Sobczak K., Piotrzkowska-Wróblewska H., Klimonda Z., Roszkowska-Purska K., Litniewski J., Ultrasound echogenicity reveals the response of breast cancer to chemotherapy , Clinical Imaging , ISSN: 0899-7071, DOI: 10.1016/j.clinimag.2019.01.021, Vol.55, pp.41-46, 2019
Dobruch-Sobczak K., Piotrzkowska-Wróblewska H., Klimonda Z., Roszkowska-Purska K., Litniewski J., Ultrasound echogenicity reveals the response of breast cancer to chemotherapy , Clinical Imaging , ISSN: 0899-7071, DOI: 10.1016/j.clinimag.2019.01.021, Vol.55, pp.41-46, 2019

Abstract:
Purpose: To evaluate the ultrasound (US) response in patients with breast cancer (BC) during neoadjuvant chemotherapy (NAC). Methods: Prospective US analysis was performed on 19 malignant tumors prior to NAC treatment and 7days after each first four courses of NAC in 13 patients (median age=57years). Echogenicity, size, vascularity, and sonoelastography were measured and compared with posttreatment scores of residual cancers burden. Results: Changes in the echogenicity of tumors after 3 courses of NAC had the most statistically strong correlation with the percentage of residual malignant cells used in histopathology to assess the response to treatment (odds ratio=60, p < 0.05). Changes in lesion size and elasticity were also significant (p < 0.05). Conclusions: There is a statistically significant relationship between breast tumors' echogenicity in US, neoplasm size, and stiffness and the response to NAC. In particular, our results show that the change in tumor echogenicity could predict a pathological response with satisfactory accuracy and may be considered in NAC monitoring.

Keywords:
Breast ultrasonography, Neoadjuvant chemotherapy, Clinical response, Breast cancer, Sonoelastography