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In this paper, a new approach to the observation of the roughness changes due to the UV light exposition is presented. The advantages of the shown method is based on the utilization of repeatable precise positioning of the sample in order to perform the imaging using atomic force microscopy, which enables continuous observation of the surface's deterioration at specific areas during every inspection step. As the degradation of the material due to a radiation is a process, the measurements are performed repeatedly after a specific dose of the energy is applied to the surface. In the presented research, three samples: two polyethylene and one polycarbonate, revealing various levels of the homogeneity were used. For each sample seven spots have been chosen and then at each ageing step they are imaged in order to provide reliable information about the roughness changes. It is shown that using this novel approach one can obtain superior degradation detection sensitivity. Additionally, it is possible to verify the impact of the morphological and material non-homogeneities on the investigation results, due to the dispersion of the roughness determination at various areas of a certain sample. © 2017 IOP Publishing Ltd.

Iwan A.,Electrotechnical Institute Warsaw | Chuchmala A.,Electrotechnical Institute Warsaw
Progress in Polymer Science | Year: 2012

Is graphene an interesting material for use in polymer photovoltaic devices? The answer to this question is not clear. Obviously, because indium tin oxide (abbreviated ITO) has become more expensive due to the limited availability of In, graphene has been proposed for use in different types of optoelectric devices, e.g., solar cells (SC), light emitting diodes (LEDs), photosensors (PS), or thin film transistors (FET). However, with respect to organic solar cells, there are currently significantly more theoretical predictions than practical realizations. For this reason, in this review, we would like to discuss the advantages and disadvantages of polymer solar cells that incorporate graphene. Graphene, which is mechanically strong, chemically stable, and inert, should improve the durability and simplify the technology of potential optoelectronic devices. In this review, we discuss the synthetic routes to produce graphene and the photovoltaic properties of organic solar cells based on graphene. With respect to photovoltaic devices, we propose to analyze graphene based on three aspects: (i) as the addition to donor or donor-acceptor materials in the bulk heterojunction (BHJ) organic photovoltaic cells, (ii) as transparent conductive electrodes and (iii) separate layers for organic photovoltaic cells. Photovoltaic (PV) parameters, such as the open circuit voltage (VOC), short circuit current (JSC), fill factor (FF) and power conversion efficiency (η, PCE), are compared for different device architectures. © 2012 Elsevier Ltd.

Krajewski W.,Electrotechnical Institute Warsaw
Electric Power Systems Research | Year: 2016

The paper deals with the numerical estimation of the electromagnetic field exposure during live-line working (LLW) on a terminal tower of a 110. kV line. The above tower is equipped with cable heads, lightning arresters and vertical cabling. This vertical cabling connects the overhead HV line with underground one. Distributions of the electric and magnetic fields in the LLW zones as well as the electric field (eddy currents) induced in the worker's organism are computed with an author's own software package. This software is based on a numerical technique that combines the boundary element and charge simulation methods. Presented computational results are related to the current European and Polish regulations regarding the workers' exposure to the electromagnetic fields. © 2016 Elsevier B.V.

Sikora A.,Electrotechnical Institute Warsaw
Measurement Science and Technology | Year: 2014

A sophisticated experiment requiring multiple micrometer-scale scanning of the same area of a sample may be performed easily if special positioning features on the surface are available. A set of nanomarkers developed using a nanoscratching technique can provide an efficient, submicron-accurate solution allowing us to investigate various phenomena. In this paper, the analysis of the roughness estimation repeatability is presented in terms of defining the accuracy of the area of interest. The obtained results confirmed the possibility of the repeatable positioning of the sample in an atomic force microscope, providing area roughness determination repeatability with a standard distribution smaller than 3%. As an example, the observation of light-caused surface degradation is presented. Also, the utilization of nanomarkers in determining the magnetic domain's rearrangement angle with an accuracy better than 0.5° is shown. © 2014 IOP Publishing Ltd.

Kazmierkowski M.P.,Warsaw University of Technology | Moradewicz A.J.,Electrotechnical Institute Warsaw
IEEE Industrial Electronics Magazine | Year: 2012

Recently, contactless (or contact-free) energy transfer (CET) systems have become more widely developed and investigated [1][4]. This innovative technology brings about new possibilities of supplying mobile devices with electrical energy by allowing elimination of cables, connectors, and/or slip rings. This increases reliability and maintenance-free operation of such systems in critical applications such as aerospace, biomedicine, multisensors, and robotics. © 2007-2011 IEEE.

Iwan A.,Electrotechnical Institute Warsaw
Journal of Molecular Liquids | Year: 2010

The optical, electrical and thermal properties of unsymmetrical imine with two fluorinated chains are described. The structure of imine was characterized by means of 1H, 13C NMR spectroscopy and elemental analyses and the results show an agreement with the proposed structure. The wide-angle X-ray diffraction [WAXD(T)] technique in different temperatures was used to probe the structural properties of the azomethine. Mesomorphic behaviour was investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) studies. Additionally, the mesomorphic behaviour of the azomethine presented in this work was compared with other azomethines. The absorption (UV-vis), photoluminescence (PL) and thermoluminescence (TL) features of the compound are documented. The sample was irradiated with a test dose of 2 Gy Co-60 gamma rays. Current-voltage (I-V) measurements were performed on an ITO/Az/Al device in the dark and during irradiation with light (under illumination of 1000 W/m2). © 2010 Elsevier B.V. All rights reserved.

The investigation of the surface properties changes at micrometer and nanometer scale, due to the presence of various factors such as: temperature, solar radiation or magnetic field, requires suitable diagnostic methods. Atomic force microscopy (AFM) is one of the most popular measurement techniques providing necessary resolution. As complex experiments may require multiple moving of the sample between instruments and AFM, one can find quantitative comparison of the results unreliable when the measurements are performed without precise positioning of investigated surface and different areas are analyzed. In this work, the utilization of the nanoscratching method in terms of development of the nanomarkers set is presented, as the solution for precise positioning of the sample in order to perform the multi-step imaging of small surface area (1 ?m×1 ?m). Various materials were used to verify the versatility of the developed method. Also, the observation of the influence of the UV radiation on the polycarbonate sample was demonstrated as the example proving the application potential of the approach.

Iwan A.,Electrotechnical Institute Warsaw
Renewable and Sustainable Energy Reviews | Year: 2015

In this review, liquid crystalline (LC) polyazomethines (PAZs) with aliphatic-aromatic moieties were investigated, taking into consideration their thermal, structural, optical and electrical properties. Liquid crystalline polymers with imine bonds in the main or side chains were analysed. The optical properties of LC polyazomethines, including UV-vis absorption, photoluminescence (PL) and thermoluminescence (TL), were studied, taking into consideration the polymer structure. Finally, the electrical properties, including the photovoltaic properties of a bulk heterojunction (BHJ) and monolayer devices based on LC polyazomethines, were investigated and compared with PAZ, which did not exhibit LC properties. In this review article, the recent research trend on LC polyazomethines is summarised. © 2015 Elsevier Ltd. All rights reserved.

Moradewicz A.J.,Electrotechnical Institute Warsaw | Kazmierkowski M.P.,Warsaw University of Technology
IEEE Transactions on Industrial Electronics | Year: 2010

Power supply based on an inductive coupled contactless energy transfer system is presented in this paper. The energy is transferred using a rotatable transformer and a power electronic converter. To minimize total losses of the system, a series resonant compensation circuit is applied assuring zero-current switching condition for insulated-gate bipolar transistors. The analytical expression of the transfer dc voltage gain is presented and discussed. The novelty of the system lies in the application of a fully digital field-programmable-gate-array-based controller and a protection system. The resonant frequency is adjusted by a primary peak current regulator. Some simulation and experimental results illustrating the operation of the developed 3-kW 60-kHz laboratory prototype are given. Although the presented power supply with a rotatable transformer is constructed mainly for robotics and manipulators, the described design and control methodology has general validity and can be applied for a wide class of contactless power supply with core or coreless transformers. © 2006 IEEE.

Benysek G.,University of Zielona Gora | Strzelecki R.,Electrotechnical Institute Warsaw
Renewable and Sustainable Energy Reviews | Year: 2011

The paper discusses the most important areas of application of power electronics arrangements in the Polish electrical power system; especially in the distribution system. The examples presented demonstrate both the need for and the purpose of further research and its applications in these fields, as well as indicating the direction of future research, with special consideration given to the research required in Poland. The proposed practical solutions for power electronics arrangements, either dedicated or capable of adaptation to the distribution systems, illustrate the ability to use the potential of Polish national research-development units. © 2010 Elsevier Ltd.

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