Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Publications from the year 2020

Show all
  • Testing Stability of Digital Filters Using Multimodal Particle Swarm Optimization with Phase Analysis
    • Damian Trofimowicz
    • Tomasz Stefański
    2020

    In this paper, a novel meta-heuristic method for evaluation of digital filter stability is presented. The proposed method is very general because it allows one to evaluate stability of systems whose characteristic equations are not based on polynomials. The method combines an efficient evolutionary algorithm represented by the particle swarm optimization and the phase analysis of a complex function in the characteristic equation. The method generates randomly distributed particles (i.e., a swarm) within the unit circle on the complex plane and extracts the phase quadrant of function value in position of each particle. By determining the function phase quadrants, regions of immediate vicinity of unstable zeros, called candidate regions, are detected. In these regions, both real and imaginary parts of the complex function change signs. Then, the candidate regions are explored by subsequently generated swarms. When sizes of the candidate regions are reduced to a value of assumed accuracy, then the occurrence of unstable zero is verified with the use of discrete Cauchy's argument principle. The algorithm is evaluated in four benchmarks for integer- and fractional-order digital filters and systems. The numerical results show that the algorithm is able to evaluate the stability of digital filters very fast even with a small number of particles in subsequent swarms. However, the multimodal particle swarm optimization with phase analysis may not be computationally efficient in stability tests of systems with complicated phase portraits.

  • Testing the Positioning Accuracy of GNSS Solutions during the Tramway Track Mobile Satellite Measurements in Diverse Urban Signal Reception Conditions
    • Mariusz Specht
    • Cezary Specht
    • Andrzej Wilk
    • Władysław Koc
    • Leszek Smolarek
    • Krzysztof Czaplewski
    • Krzysztof Karwowski
    • Paweł S. Dąbrowski
    • Jacek Skibicki
    • Piotr Chrostowski
    • Jacek Szmagliński
    • Sławomir Grulkowski
    • Sławomir Judek
    2020 Full text ENERGIES

    Mobile Global Navigation Satellite System (GNSS) measurements carried out on the railway consist of using satellite navigation systems to determine the track geometry of a moving railway vehicle on a given route. Their purposes include diagnostics, stocktaking, and design work in railways. The greatest advantage of this method is the ability to perform measurements in a unified and coherent spatial reference system, which effectively enables the combining of design and construction works, as well as their implementation by engineering teams of diverse specialties. In the article, we attempted to assess the impact of using three types of work mode for a GNSS geodetic network [Global Positioning System (GPS), GPS/Global Navigation Satellite System (GLONASS) and GPS/GLONASS/Galileo] on positioning availability at three accuracy levels: 1 cm, 3 cm and 10 cm. This paper presents a mathematical model that enables the calculation of positioning availability at these levels. This model was also applied to the results of the measurement campaign performed by five GNSS geodetic receivers, made by a leading company in the field. Measurements with simultaneous position recording and accuracy assessment were taken separately on the same route for three types of receiver settings: GPS, GPS/GLONASS and GPS/GLONASS/Galileo in an urban area typical of a medium-sized city. The study has shown that applying a two-system solution (GPS/GLONASS) considerably increases the availability of high-precision coordinates compared to a single-system solution (GPS), whereas the measurements with three systems (GPS/GLONASS/Galileo) negligibly increase the availability compared to a two-system solution (GPS/GLONASS).

  • Tests of bond between concrete and steel bars – literature background and program of own research
    • Marcin Burdziński
    • Maciej Niedostatkiewicz
    • Patryk Ziółkowski
    2020 Full text Budownictwo i Architektura

    This article deals with the issue of the bond between concrete and reinforcement. The bond is crucial for reinforced concrete elements because it is possible to transfer forces (stresses) from concrete to the reinforcement. Basic information related to the cooperation of concrete and rebars was recalled in the article. Selected issues concerning theoretical and numerical analysis as well as experiments of the bond phenomenon were presented. The article also proposes its own concept of experimental studies on the bond on two types of specimens: so-called short specimen and large specimen that will be subjected to pull-out tests. The described concept is ultimately to form the basis for creating a numerical model, enabling the simulation of bond in various reinforced concrete elements, calibrated based on the results of experimental studies.

  • Texture Features for the Detection of Playback Attacks: Towards a Robust Solution
    • Maciej Smiatacz
    2020 Advances in Intelligent Systems and Computing

    This paper describes the new version of a method that is capable of protecting automatic speaker verification (ASV) systems from playback attacks. The presented approach uses computer vision techniques, such as the texture feature extraction based on Local Ternary Patterns (LTP), to identify spoofed recordings. Our goal is to make the algorithm independent from the contents of the training set as much as possible; we look for the descriptors that would allow the method to detect attacks performed in an environment entirely different from the training one and with the use of the equipment that differs considerably from the devices that captured the training samples. The final form of our method, based on the previously presented proof of concept, performs significantly better than the reference Textrogram algorithm.

  • The abrasive wear resistance of coatings manufactured on high-strength low-alloy (HSLA) offshore steel in wet welding conditions
    • Jacek Tomków
    • Artur Czupryński
    • Dariusz Fydrych
    2020 Full text Coatings

    Some marine and offshore structure elements exploited in the water cannot be brought to the surface of the water as this will generate high costs, and for this reason, they require in-situ repairs. One of the repair techniques used in underwater pad welding conditions is a wet welding method. This paper presents an investigation of the abrasive wear resistance of coatings made in wet welding conditions with the use of two grades of covered electrodes—an electrode for underwater welding and a commercial general use electrode. Both electrodes were also used for manufacturing coatings in the air, which has been also tested. The Vickers HV10 hardness measurements are performed to demonstrate the correlation in abrasive wear resistance and the hardness of each specimen. The microscopic testing was performed. For both filler materials, the coatings prepared in a water environment are characterized by higher resistance to metal–mineral abrasion than coatings prepared in an air environment—0.61 vs. 0.44 for commercial usage electrode and 0.67 vs. 0.60 for underwater welding. We also proved that in the water, the abrasive wear was greater for specimens welded by the general use electrode, which results in a higher hardness of the layer surface. In the air welding conditions, the layer welded by the electrode for use in the water was characterized by a lower hardness and higher resistance to metal–mineral abrasion. The microstructure of the prepared layers is different for both the environment and both electrodes, which results in abrasive wear resistance.

  • The Analysis of Working Parameters Decrease in Photovoltaic Modules as a Result of Dust Deposition
    • Ewa Klugmann-Radziemska
    • Małgorzata Rudnicka
    2020 Full text ENERGIES

    The aspect of dust accumulation on the surface of photovoltaic (PV) modules should be thoroughly understood in order to minimize possible obstacles affecting energy generation. Several elements affect the amount of pollutant gathered on the surface of a solar device, mainly its localization, which is irreversibly linked to factors such as annual rainfall, occasional snow coverage, or, in a dry climate, increased blow of dust during sandstorms and higher concentration of soil particles in desert areas. Other than weather conditions in the region, PV installation type also plays an important role as a more horizontal position is favorable for the accumulation of soil. The research carried out and presented in this paper was done for dust accumulated naturally on PV modules kept in outdoor conditions and dust artificially sieved onto the front glass cover of modules. The experiment performed by the authors, including artificially deposited dust, defined the linear relationship between surface dust density of different types of contaminants and efficiency decline up to 10% for two different PV modules. The additional field study carried out in external conditions for a coastal region in Northern Poland concluded that, after one year, exposition photovoltaic conversion efficiency can be over 10% lower, with a slight performance improvement for the autumn season characterized by heavy rainfall.

  • THE APPLICATION OF THE MECHANOCHEMICAL SYNTHESIS FOR THE PREPARATION OF ADVANCED CERAMICS BASED ON BARIUM TITANATE
    • Barbara Garbarz-Glos
    • Wojciech Bąk
    • Andrzej Budziak
    • Piotr Dulian
    • Agata Lisińska-Czekaj
    • Dionizy Czekaj
    2020 Full text ARCHIVES OF METALLURGY AND MATERIALS

    In the present study, the lead-free BaTi1-xZrxO3 (for x = 0, 0.05 and 0.15) ceramics were prepared by High-Energy Ball Milling and heat treatments. The performed X-ray, SEM and EDS measurements confirmed high purity, good quality and the expected quantitative composition of the obtained samples. The study of dielectric properties was performed by means of broadband dielectric spectroscopy at the frequency ranging from 0.1 Hz to 10 MHz. The obtained measurement data, analyzed in accordance with the Arrhenius formalism demonstrated the presence of relaxation type dielectric mechanisms. The impedance answer of studied ceramic materials indicated the presence of two relaxation processes: one with a dominant resistive component and the other with a small capacitive component. The observed dielectric relaxation process is temperature dependent and has a “non-Debye” character.

  • The application of the Superpave method of climatic zones analysis in Poland with regard to bitumen performance grading
    • Marek Pszczoła
    • Dawid Ryś
    • Piotr Jaskuła
    2020

    Currently in Poland, similarly as in the other EU countries, road bitumens are tested and classified with regard to mainly the penetration value determined at the tempera-ture of 25C. It should be noted that this classification is not correlated with the cli-matic conditions in which the bitumens are to serve in the road pavement. Towards the end of the last century a new system of bitumen grading was developed and im-plemented as part of the American Strategic Highway Research Program (SHRP). This paper presents the results of analyses concerning the determination of the tempera-tures at which bituminous binders serve in the Polish climatic conditions. A division of the area of Poland into climatic zones depending on the required performance grades (PGs) determined for bitumens on the basis of climatic data from meteorological sta-tions for a period of minimum 20 years is presented. It is proposed to select bitumens depending on the climatic zone in Poland, taking into account the proper probability level which follows from the road class.

  • The behavioural model of graphene field-effect transistor
    • Maciej Łuszczek
    • Marek Turzyński
    • Dariusz Świsulski
    2020 Full text International Journal of Electronics and Telecommunications

    The behavioural model of a graphene field-effect transistor (GFET) is proposed. In this approach the GFET element is treated as a “black box” with only external terminals available and without considering the physical phenomena directly. The presented circuit model was constructed to reflect steady-states characteristics taking also into account GFET capacitances. The authors’ model is defined by a relatively small number of equations which are not nested and all the parameters can be easily extracted. It was demonstrated that the proposed model allows to simulate the steady-state characteristics with the accuracy approximately as high as in the case of the physical model. The presented compact GFET model can be used for circuit or system-level simulations in the future.

  • The CDIO model in architectural education and research by design
    • Lucyna Nyka
    • Jan Cudzik
    • Katarzyna Urbanowicz
    2020 Full text World Transactions on Engineering and Technology Education

    Architectural education has always been related to experimentation: that is, defining concepts, drawing sketches, working on models, then testing and modifying them. This activity mirrors the CDIO learning methods and objectives. Despite this, research studies into the applicability of the CDIO model in architectural curricula are scarce. In the discipline of architecture, hands-on experiences are associated not only with one of the most effective methods of education, but also with a particular way of carrying out research, that is research by design. In this article, the authors present the integration of the CDIO framework into the architectural engineering curricula at Gdańsk University of Technology, Gdańsk, Poland, discuss the results, and indicate which components of architectural education have benefited most from this integration. Another objective was to initiate a discussion on the potential impacts of implementing CDIO into architectural curricula, and its relation to the research by design concept.

  • The correlation between the MRI-evaluated ectopic fat accumulation and the incidence of diabetes mellitus and hypertension depends on body mass index and waist circumference ratio.
    • Mariusz Kaszubowski
    • J Pieńkowska
    • B. Brzeska
    • O. Kozak
    • A. Jankowska
    • Edyta Szurowska
    2020 Full text PLOS ONE

    The widespread presence of overweight and obesity increases with every decade, and the number of people with body mass index (BMI) >30 kg/m2 has doubled in the last 30 years. The aim of the study is to assess the correlation between MRI-evaluated ectopic fat accumulation in pancreas, skeletal muscles and liver and the incidence of type 2 diabetes and hypertension, depending on BMI and waist circumference ratio. This prospective study included 267 consecutive patients who were referred to abdominal MRI and underwent a standard clinical assessment with BMI and waist circumference ratio calculation. Ectopic fat accumulation in pancreas, skeletal muscles and liver was evaluated in magnetic resonance imaging using the fat-water separated Dixon imaging. There were statistically significant differences in mean steatosis of all assessed organs in the group of patients with type 2 diabetes or hypertension in comparison to the non-diabetic group as well as to the group without hypertension. It has been observed that pancreas and skeletal muscles are more susceptible to fat accumulation than liver. According to our results, there is a relation between the fat content in muscles, pancreas and liver, the incidence of type 2 diabetes and hypertension and also body mass index and waist circumference ratio. We believe that future studies should aim to determine whether the use of fat content measurement in certain organs could be used as a biomarker that can enable early detection of reversible metabolic changes, as well as their subsequent monitoring.

  • The Design Development of the Sliding Table Saw Towards Improving Its Dynamic Properties
    • Kazimierz Orłowski
    • Przemysław Dudek
    • Daniel Chuchała
    • Wojciech Blacharski
    • Tomasz Przybyliński
    2020 Full text Applied Sciences-Basel

    Cutting wood with circular saws is a popular machining operation in the woodworking and furniture industries. In the latter sliding table saws (panel saws) are commonly used for cutting of medium density fiberboards (MDF), high density fiberboards (HDF), laminate veneer lumber (LVL), plywood and chipboards of different structures. The most demanded requirements for machine tools are accuracy and precision, which mainly depend on the static deformation and dynamic behavior of the machine tool under variable cutting forces. The aim of this study is to present a new holistic approach in the process of changing the sliding table saw design solutions in order to obtain a better machine tool that can compete in the contemporary machine tool market. This study presents design variants of saw spindles, the changes that increase the critical speeds of spindles, the measurement results of the dynamic properties of the main drive system, as well as the development of the machine body structure. It was proved that the use of only rational imitation in the spindle design on the basis of the other sliding table saws produced does not lead to the expected effect in the form of correct spindle operation.

  • The dispersive micro-solid phase extraction method for MS-based lipidomics of human breast milk*
    • Inal Bakhytkyzy
    • Weronika Hewelt-Belka
    • Agata Kot-Wasik
    2020 Full text MICROCHEMICAL JOURNAL

    A simple and rapid microextraction method ensuring high lipidome coverage was developed for liquid chromatography mass spectrometry (LC-MS)-based lipidomics of human breast milk. The dispersive microsolid phase extraction (D-µ-SPE) technique, coupled with the design of experiment (DoE) method, enabled the study of the influence of several conditions (desorption solvent, stationary phase ratio, and sorption and desorption time) on the lipid extraction process of various lipid classes. The D-µ-SPE-based method, which used a mixture of C18 and zirconia-coated silica gel as the sorbent, allowed for the extraction of a wide range lipid classes characterized by different concentration levels. The developed method simplified the extraction procedure for lipidomics without loss of good reproducibility (70% of the MFs had peak volume %RSD <20% for all the tested stationary phases). The highest lipidome coverage was achieved when 100 µL of the human breast milk (HBM) sample was extracted using 27 mg of C18 mixed with 3 mg of zirconia-coated silica gel as the sorbent and methanol:2-propanol: ammonium hydroxide (14:81:5 v/v/v) mixture as the desorption solvent. The sorption and desorption time did not influence the number of extracted molecular features. The advantages of the present method over the traditional SPE and liquid-liquid extraction (LLE) commonly used in lipidomics are the possibility of mixing sorbents with various sorption mechanisms, which ensures high lipidome coverage, and the use of a small number of materials, including the sorbent and organic solvent.

  • The dynamic signature verification using population-based vertical partitioning
    • Marcin Zalasiński
    • Krzysztof Cpałka
    • Tacjana Niksa-Rynkiewicz
    2020

    The dynamic signature is an attribute used in behavioral biometrics for verifying the identity of an individual. This attribute, apart from the shape of the signature, also contains information about the dynamics of the signing process described by the signals which tend to change over time. It is possible to process those signals in order to obtain descriptors of the signature characteristic of an individual user. One of the methods used in order to determine such descriptors is based on signals partitioning. In this paper, we propose a new method using a population-based algorithm for determining vertical partitions of the signature and its descriptors. Our method uses a Differential Evolution algorithm for signals partitioning and an authorial one-class fuzzy classifier for verifying the effectiveness of this process. In the simulations, we use a commercial BioSecure DS2 dynamic signature database.

  • The effect of Ag, Au, Pt, and Pd on the surface properties, photocatalytic activity and toxicity of multicomponent TiO2-based nanomaterials
    • Anna Malankowska
    • Alicja Mikołajczyk
    • Joanna Mędrzycka
    • Izabela Wysocka
    • Grzegorz Nowaczyk
    • Marcin Jarek
    • Tomasz Puzyn
    • Ewa Mulkiewicz
    2020 Environmental Science-Nano

    Multicomponent TiO2-based nanomaterials (MC-NMs) show better physicochemical properties than their individual components or bulk materials. However, the same unique properties that offer innovative applications might also pose unknown risks to human health and the environment. In this context, TiO2- based nanomaterials with a mixture of noble metal precursors (Ag, Au, Pt, and Pd) for large-scale technological applications in air purification were designed, synthesized and characterized. The influence of the type and amount of noble metal precursor on the optical properties and photocatalytic activity of MC-NMs and their toxicity to mouse embryo fibroblast cell line (BALB/3T3), human lung cell line (A549) and human liver cell line (HepG2) was investigated. A hazard assessment of the designed TiO2-based MCNMs was performed for the first time according to the standards developed under the Joint Research Center and NANoReg2 project (Horizon 2020). The threshold concentration of monometallic NPs that ensure high photocatalytic activity without increasing hazard to humans and the environment was determined. The results indicated that the most effective sample is represented by the 0.1Ag_0.1Au_0.1Pt_1Pd/TiO2 photocatalyst, in which noble metal NPs demonstrated a synergistic effect on photocatalytic activity without increasing the toxicity (safe MC-NMs with 86% toluene degradation after 1 h of irradiation, efficiency 5 times higher than that of pristine TiO2). The obtained results confirm that systematic knowledge and proper manipulation of component concentration may lead to rational design of safe TiO2-based MC-NMs with wide application in air purification under solar energy.

  • The Effect of AgInS2, SnS, CuS2, Bi2S3 Quantum Dots on the Surface Properties and Photocatalytic Activity of QDs-Sensitized TiO2 Composite
    • Anna Malankowska
    • Daria Kulesza
    • Jakub Sowik
    • Onur Cavdar
    • Tomasz Klimczuk
    • Grzegorz Trykowski
    • Adriana Zaleska-Medynska
    2020 Full text Catalysts

    The eect of type (AgInS2, SnS, CuS2, Bi2S3) and amount (5, 10, 15 wt%) of quantum dots (QDs) on the surface properties and photocatalytic activity of QDs-sensitized TiO2 composite, was investigated. AgInS2, SnS, CuS2, Bi2S3 QDs were obtained by hot-injection, sonochemical, microwave, and hot-injection method, respectively. To characterize of as-prepared samples high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diraction (XRD), UV-Vis spectroscopy and photoluminescence (PL) emission spectroscopy were applied. The size of AgInS2, SnS, CuS2, Bi2S3 QDs were 12; 2–6; 2–3, and 1–2 nm, respectively. The QDs and QDs-sensitized TiO2 composites obtained have been tested in toluene degradation under LEDs light irradiation (max = 415 nm and max = 375 nm). For pristine QDs the eciency of toluene degradation increased in the order of AgInS2 < Bi2S3 < CuS < SnS under 375 nm and AgInS2 < CuS < Bi2S3 < SnS under 415 nm. In the presence of TiO2/SnS QDs_15% composite, 91% of toluene was degraded after 1 h of irradiation, and this eciency was about 12 higher than that for pristine QDs under 375 nm. Generally, building the TiO2/AgInS2 and TiO2/SnS exhibited higher photoactivity under 375 nm than the pristine TiO2 and QDs which suggests a synergistic eect between QDs and TiO2 matrix.

  • The effect of dehydration/rehydration of bacterial nanocellulose on its tensile strength and physicochemical properties
    • Alicja Stanisławska
    • Hanna Staroszczyk
    • Marek Szkodo
    2020 Full text CARBOHYDRATE POLYMERS

    Bacterial nanocellulose (BNC) is a natural biomaterial with a wide range of biomedical applications. BNC contains 99 % of water which makes it too thick to be used as a bioimplant material. The aim of the work was to determine the effect of the BNC dehydration followed by rehydration on its mechanical and physicochemical properties, in the context of the use of BNC as bio-prostheses in the cardiovascular system. Dehydration involved the convection-drying at 25 and 105 °C, and the freeze-drying, while rehydration - the soaking in water. All modified BNC samples had reduced thickness, and results obtained from FT-IR, XRD, and SEM analysis revealed that 25 °C BNC convection-dried after soaking in water was characterized by the highest: tensile strength (17.4 MPa), thermal stability (253 °C), dry mass content (4.34 %) and Iα/Iβ ratio (1.10). Therefore, 25 °C convection-dried BNC followed by soaking in water can be considered as a material suitable for cardio- vascular implants.

  • THE EFFECT OF DRYING INTENSITY ON THE COLOR CHANGES OF PINE WOOD (PINUS SYLVESTRIS L.)
    • Aleksandra Konopka
    • Jacek Barański
    • Kazimierz Orłowski
    • Daniel Chuchała
    2020 Full text Trieskove a Beztrieskove Obrabanie Dreva

    The effect of the selection of drying process parameters on the color change of Scots pine wood (Pinus Sylvestris L.) is presented. In this work the experimental studies have been performed. The research focused on the influence of drying intensity on the changes of color after drying process. Intensity of drying process was determined on the basis of the average drying gradient. To determine the color of wood before and after drying process the series of experiments have been performed, using color reader device. The wood samples were dried according to three different drying modes, namely: mild, normal and intense. Experiments were conducted in the laboratory dryer. The measurement of wood samples was made using international standards: ISO 11664-2 and ISO 11664-4 of total color change after drying. As a result of the performed statistical tests, there were observed statistically significant color changes of the wood surface for intensive drying mode.

  • The Effect of Fly Ash Microspheres on the Pore Structure of Concrete
    • Elżbieta Haustein
    • Aleksandra Kuryłowicz-Cudowska
    2020 Full text Minerals

    The fly ash microspheres (FAMs) formed during the mineral transformation stage in coal combustion are hollow spherical particles with a density less than water. This paper presents the results of X‐ray micro‐computed tomography and an automatic image analysis system of the porosity in the structure of hardened concrete with microspheres. Concrete mixtures with ordinary Portland cement and two substitution rates of cement by microspheres—5% and 10%—are investigated. For all considered mixes, a constant water/binder ratio (w/b) equal to 0.50 was used. The distribution of the air voids and the compressive strength of the concrete were tested after 28 days. With the increasing mass of cement replacement by FAMs, the compressive strength decreases after 28 days. The total volume of the air voids in hardened concrete with fly ash microspheres tested by X‐ray varies from 5.1% to 7.4%. The closed pores constitute more than 80% of the total content of air pores. The study proves that the use of microspheres grains with specific dimensions has a significant impact on concrete porosity. Their application in concrete technology can be an alternative aeration solution for fresh concrete mixes and an effective method for utilization.

  • The Effect of Laser Re-Solidification on Microstructure and Photo-Electrochemical Properties of Fe-Decorated TiO2 Nanotubes
    • Piotr Kupracz
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Jakub Wawrzyniak
    • Katarzyna Siuzdak
    2020 Full text Materials

    Fossil fuels became increasingly unpleasant energy source due to their negative impact on the environment; thus, attractiveness of renewable, and especially solar energy, is growing worldwide. Among others, the research is focused on smart combination of simple compounds towards formation of the photoactive materials. Following that, our work concerns the optimized manipulation of laser light coupled with the iron sputtering to transform titania that is mostly UV-active, as well as exhibiting poor oxygen evolution reaction to the material responding to solar light, and that can be further used in water splitting process. The preparation route of the material was based on anodization providing well organized system of nanotubes, while magnetron sputtering ensures formation of thin iron films. The last step covering pulsed laser treatment of 355 nm wavelength significantly changes the material morphology and structure, inducing partial melting and formation of oxygen vacancies in the elementary cell. Depending on the applied fluence, anatase, rutile, and hematite phases were recognized in the final product. The formation of a re-solidified layer on the surface of the nanotubes, in which thickness depends on the laser fluence, was shown by microstructure studies. Although a drastic decrement of light absorption was recorded especially in UV range, laser-annealed samples have shown activity under visible light even 20 times higher than bare titania. Electrochemical analysis has shown that the improvement of photoresponse originates mainly from over an order of magnitude higher charge carrier density as revealed by Mott-Schottky analysis. The results show that intense laser light can modulate the semiconductor properties significantly and can be considered as a promising tool towards activation of initially inactive material for the visible light harvesting.