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1

Optimization of performance parameters of high-contrast subwavelength grating with high reflectivity for bio-sensing applications

Sharma Pallavi, Kaler R. S., Teotia Pradeep

Optica Applicata

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2024

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Vol. 54, nr 1

115--122

EN

Highly reflective mirror technologies are majorly required in bio-sensing applications to eliminate complex multiple diffraction orders. In this paper, various grating parameters, i.e. width, thickness, and period are analyzed to get optimized values and high reflectivity for high-contrast subwavelength grating (HCSG) structure. Besides these parameters, polarization modes, angle of incidences, and refractive index have been diversely analyzed to monitor their effects on HCSG structure with respect to reflectivity. The simulation results manifest that the optimized parameters help to achieve the best reflectivity that can be further utilized in bio-sensing applications.

2

Comparison of linear and circular polarization in foggy environments at UV-NIR wavelengths

Zeng Xiangwei, Li Yahong, Chen Xueye, Zheng Hongxia

Optica Applicata

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2023

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Vol. 53, nr 1

153--160

EN

This paper investigates the polarization persistence of linear polarization and circular polarization in foggy environments from ultraviolet (UV) to near-infrared (NIR). Using polarization tracking Monte Carlo simulation for varying particle size, wavelength, refractive index, and detection distance, it is shown that linear polarization and circular polarization exhibit different persistence performance. For wet haze of 0.6 μm mean diameter particles, right-handed circular polarization shows better persistence than parallel polarization at wavelengths of 0.36, 0.543 and 1.0 μm. But parallel polarization shows better persistence at wavelengths of 1.55, 2.1 and 2.4 μm. For wet haze of 1.0 μm mean diameter particles, right-handed circular polarization shows better persistence at wavelengths of 0.36, 0.543, 1.0 and 1.55 μm. But parallel polarization shows better persistence at wavelengths of 2.1 and 2.4 μm. For wet haze of 2.0 μm particles and radiation fog and advection fog, right-handed circular polarization shows better persistence at all simulated wavelengths. In short, right-handed circular polarization persists better than parallel polarization in most scenarios, however, with increasing wavelength and decreasing particle size, parallel polarization gradually persists better than right-handed circular polarization. Finally, anisotropy factor for various particle models is used to map the propagation law of right-handed circular polarization and parallel polarization.

3

Non-destructive investigation of corrosion current density in steel reinforced concrete by artificial neural networks

Sadowski L.

Archives of Civil and Mechanical Engineering

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2013

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Vol. 13, no. 1

104--111

EN

Corrosion of the steel reinforcement in concrete is an important problem for the civil engineering. Inspection techniques are needed to assess the corrosion in order to protect and repair concrete structures. Many studies were performed to establish a series of corrosion rate assessment methods. A method of providing a direct evaluation of the corrosion rate by corrosion current density measurement is Linear Polarisation Resistance (LPR). The main drawback is that it requires a localised breakout of the concrete cover. The corrosion of the steel reinforcement is monitored by measuring the resistivity of the concrete. The purpose of this paper is to use the resistivity four-probe method and galvanostatic resistivity measurement together with neural networks to assess the corrosion rate of steel in concrete without a direct connection to the reinforcement. Three parameters determined by two non-destructive resistivity methods together with the air temperature were employed as input variables, and corrosion current density, predicted by the destructive LPR method, acted as the output variable. The results shows that it is possible to predict corrosion current density in steel reinforced concrete by using the model based on artificial neural networks on the basis of parameters determined by two non-destructive resistivity measurement techniques.

4

Reliability and influences on dielectric diagnostic methods to evaluate the ageing state of oil-paper insulations

Koch M., Feser K.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

95-101

EN

Dielectric measurements and diagnostic methods are established procedures to evaluate moisture as an ageing indicator in commonly used oil-paper insulations of power transformers. Both the measurements themselves as well as the analysis of collected data contain several uncertainties and sources of error. This investigation discusses the sources of error and gives a further insight to the influences of transformer insulation design (geometry), insulation temperature, moisture equilibrium in oil and paper and other aspects regarding practical measurements. The dominating impact on dielectric analysis is related to the insulation temperature rather than insulation geometry. Limits and influences on linear modelling of multilayer insulations by equivalent circuits are described too. The investigation includes all the common dielectric diagnostic methods for oil-paper insulations: Recovery Voltage Method (RVM), Polarisation and Depolarisation Currents (PDC) and Frequency Domain Spectroscopy (FDS).

5

Measurements of frozen-in polarization in PET electrets using E-j method

Motyl E.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

41-45

EN

Step elcctroacoustic (SEA) and thermally stimulated depolarisation (TSD) techniques were applied for analysis of electret slate in polyethylene-terephthalate samples after corona charging at low and high temperatures. Measurements of electric field distributions E and current density jTSD during thermally stimulated discharging allow to get information on real charge density and quasi-frozen polarisation in dielectric. The above E-j method is a useful tool for measurement of local values of real and polarization charges in PET electrets and their decay in time. Positive and negative coronas as well as temperature of charging affect the storage of real charges and polarisation in PET electrets.

6

Różnorodność systemów cyfrowych linii radiowych

Bogucki J.

Elektronika : konstrukcje, technologie, zastosowania

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2004

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Vol. 45, nr 6

41-43

PL

Podano parametry systemowe i podstawową konfigurację współczesnych systemów radiowych. Omówiono zagadnienie polaryzacji sygnału radiowego. Podano zakres pracy systemów radiowych służb stałych oraz przykłady takich systemów.

EN

The system parameters and basic configuration of fixed digital radio systems are given. The article describes polarisation problem of radio signal. Frequency bands and examples of various systems are given.

7

Application of polarisation-maintaining side-hole fibres do direct force measurement

Wierzba P., Kosmowski B.

Opto-Electronics Review

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2003

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Vol. 11, No. 4

305-311

EN

The use of single mode polarisation-maintaining side-hole (SMPM-SH) fibres for direct measurement of transverse force has been studied theoretically and experimentally. Based on the results of a qualitative analysis of stress distribution in such a fibre, it was predicted that SMPM-SH fibres can exhibit higher sensitivity to transverse force than a standard SMPM fibre. The modelling of two types of SMPM-SH fibres with bow-tie and round holes was conducted using finite element method and modifield coupled-mode method. It showed that while there is a marked increase of the sensitivity for the SMPM-SH fibre with bow-tie holes, the sensitivity of the SMPM-SH fibre with round holes can be even lower than that of a standard SMPM fibre. Subsequently, in an experiment, which to the authors' knowledge is the first application of SMPM-SH fibres to direct transverse force measurement, the sensitivity of an SMPM-SH fibre with bow-tie holes was measured. Measurement results agreed well with theoretical predictions. However, more systematic research is needed to determine the realisationship between the sensitivity, dimensions and geometry of the holes.

8

Zastosowanie zjawiska polaryzacji wzbudzonej do badań szczelinowatości skał węglanowych w otworach wiertniczych

Kozik W.

Prace Instytutu Górnictwa Naftowego i Gazownictwa

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2002

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nr 116 wyd. konferencyjne

255--259

PL

Metodę pola wzbudzonego wykorzystywano dotąd do badań w otworach węglowych i rudnych. W otworach naftowych metoda ta nie była dotąd szerzej wykorzystywana m.in. ze względu na stosowanie zmineralizowanych płuczek. W pracy przedstawiono próbę zastosowania nowej modyfikacji tej metody, a mianowicie profilowanie statycznego pola wzbudzonego do badań i lokalizacji stref szczelinowych kompleksów węglanowych w otworach naftowych. Opisano aparaturę pomiarową oraz technikę pomiarów otworowych. Przedstawiono praktyczne przykłady zastosowań metody w otworach wiertniczych.

EN

A method of induced field, until now, was applied in coal and ore wells. However, in oil wells this method was not extensively used so far due to the presence of mineralized drilling fluids. Attempts to apply new modification of this method are presented in this work, namely - the use of induced static field logging wos used to inverstigage and localize the fracture zones of carbonate complexes in oil wells. A specification of equipment and borehole measurement techniques were described followed by the presentation of practical examples of application of this method.

9

Anharmonic polarization of ferroelectric ceramics in alternating field. I. Large damping

Aleksiejuk M., Knyazev M. A.

Journal of Technical Physics

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2002

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Vol. 43, no 3

257-263

EN

Polarization of ferroelectric ceramics in an alternating electric field with frequency UJ in a case when damping is large is considered. For the two-type of ions phenomenological model of ferroelectrics which includes only two types of ions of the crystalic lattice, the nonlinear anharmonic equation for polarization is considered. By perturbation method the solution of this equation in the first order in anharmonicity coefficient is constructed. It is shown that an additional oscillations of polarisation with frequency omega/2 and phase shift between real and imaginary components of polarization appeared.

10

Polarisation switching in vertical-cavity surface-emitting lasers: from experimental observations to applications

Verschaffelt G., Panajotov K., Albert J., Nagler B., Peeters M., Danckaert J., Veretennicoff I., Thienpont H.

Opto-Electronics Review

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2001

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Vol. 9, No. 3

257-268

EN

Touted as promising components for present and future data-communication and sources for photonic switching fabrics, vertical-cavity surface-emitting lasers (VCSELs) have been studied in detail during the past years, with a focus on their static light-current and dynamic intensity modulation characteristics. Their superior beam quality, low power consumption, Gigahertz modulation bandwidth and the possibility of manufacturing these devices in 2D arrays are often cited as substantial advantages compared to traditional edge-emitting semiconductor lasers or light emitting diodes. A disadvantage of VCSELs is that the polarisation of the emitted light is not defined a priori due to the VCSEL’s quasi-cylindrical symmetry and its direction of lasing perpendicular to the active region. However, real VCSELs do emit linearly polarised light and often polarisation switching from one state to the orthogonal one is observed as the current is changed. In this contribution we will discuss the experimental characteristics of this intriguing polarisation switching phenomenon. We will give an overview of various physical mechanism proposed to explain the polarisation behaviour of these devices and we will illustrate the use of this polarisation switching in the implementation of reconfigurable optical interconnects.

11

Polarisation behaviour of different fiber-optic interferometer configurations under temperature changes.

Jaroszewicz L.R.

Optica Applicata

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2001

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Vol. 31, nr 2

399-423

EN

Deals with presents the theoretical investigation into the influence of temperature on the fiber-optic interferometer action for different configuration of the latter. Based on the phenomenological description of interference phenomena in the optical fiber, the role of coherence and polarisation in the fiber-optic interferometer is discussed. The final conclusions are used in the main part of the paper connected with an analysis of temperature influence on the action of different fiber-optic interferometer configurations. This analysis is based on the Jones matrix formalism applied to interferometers of minimal functional configuration. Finally, it is suggested using the fiber-optic ellipsometer for polarisation controlling.

12

Effective properties of layered piezoelectric material with gradient of polarizations

Bytner S., Gałka A., Gambin B.

Journal of Technical Physics

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2001

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Vol. 42, no 4

437--447

EN

In the paper, homogenization of heterogeneous piezoelectricity with polarization gradient is performed to obtain effective material coefficients. The method of two-scale asymptotic expansion is used and the layered composite structure is analysed in details.

13

Estymacja szczelinowatości skał węglanowych metodami polaryzacji elektrycznej

Kozik W.

Prace Instytutu Górnictwa Naftowego i Gazownictwa

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2000

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nr 110 wyd. konferencyjne

311--314

EN

Up to the present state of knowledge a system of fractures is determined first of all by electrokinetical processes, occurring in rocks. Filtration of fluids through pore spaces of rocks results in their electrical polarisation. The polarisation is much stronger in rocks with fractured porosity than in rocks with porosity of another type. The paper provides results of experiments which confirm the thesis. Measurements have been made on fractured Carboniferous limestones from Carpathians, being polarised by natural electrokinetical processes.

14

Polarization of ferroelectric ceramics in alternating field

Aleksiejuk M., Knjazev M.

Journal of Technical Physics

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2000

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Vol. 41, no 1

49-54

EN

The problem of studying the behaviour of polarization for ferroelectric ceramics in the external alternating electric field is considered. For the model of constant dipoles with fixed masses, are presented the analytical expressions for polaLrization in two cases of large and small damping. The peculiarities of the mechanism of transition from metastable multidomain state in ferroelectric ceramic crystal to a stable one-domain state are shown.

15

Elektrochemiczne i korozyjne właściwości Ti6Al4V ELI w roztworach kwasu fosforowego

Krasicka-Cydzik E.

Inżynieria Biomateriałów

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1999

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R. 2, nr 7-8

26--32

PL

Barierowa warstwa tlenkowa wytworzona na powierzchni metalu podczas elektrochemicznej obróbki anodowej implantowych stopów tytanu w roztworach kwasu fosforowego posiada właściwości stymulujące procesy osseointegracji w środowisku biologicznym. W pracy przedstawiono badania wczesnych etapów anodowania stopu tytanu Ti6Al4V ELI w wodnych roztworach kwasu fosforowego o różnym stężeniu. Zastosowane techniki polaryzacyjne - potencjodynamiczna i galwanostatyczna – wykazały możliwość potwierdzenia na drodze elektroanalitycznej udziału jonów fosforanowych w procesie anodowania.

EN

Barrier oxide films formed by electrochemical anodic treatment of implant titanium alloys in phosphoric acid solutions influence advantageously the stimulation of osteointegration processes in human body. The investigation of early stages of the Ti6A14V ELI alloy oxidation in aqueous solutions of phosphoric acid of different concentrations are presented. The use of potentiodynamic and galvanostatic polarization techniques revealed the possibility to confirm the electrochemical incorporation of phosphate ions into the surface oxide layer of the alloy.

16

Numerical model of electrostatic barrier effect in a point-plane air gap in presence of positive space charge

Boubakeur A., Mokhnache L., Boukhtache S.

Archives of Electrical Engineering

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1999

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Vol. 48, nr 3

323-340

EN

A model allowing determination of the electric field and potential in the presence of a space charge (positive ions) determined on the basis of the knowledge of efficient ionisation factor alpha(-) has been developed. The distribution of the space charge is done in spherical concentric volumes. The calculation is developed in a hyperboloidal point-barrier-plane arrangement under a positive voltage. The polarisation field is taken into account. To calculate the electric field the finite element method has been applied. Results show that electric stress in the air gap decreases due to the space charge left in the point-barrier gap, but it increases suddenly at the handle of the avalanches and on the barrier surface facing the point. This latter effect related to the presence of the dielectric barrier is due to the polarisation charge. The space charge variation is not smooth. It presents a sudden increase when alpha(-) changes.

PL

Przedstawiono model umożliwiający obliczenia rozkładu potencjału i pola elektrycznego w obecności dodatniego ładunku przestrzennego, wyznaczonego w oparciu o znajomość efektywnego współczynnika jonizacji alfa(-). Ładunek przestrzenny występuje w wyodrębnionej przestrzeni kulistej. Analiza dokonywana jest w układzie elektrod ostrze hiperboloidalne - bariera - płyta z dodatnią biegunowością ostrza. W analizie uwzględniono pole polaryzacyjne bariery. W obliczeniach polowych wykorzystano metodę elementów skończonych. Uzyskano potwierdzenie, że ładunek przestrzenny powoduje zmniejszenie natężenia pola, które wzrasta gwałtownie w przypadku procesów lawinowych, gdy powierzchnia ładunku przestrzennego dociera do ostrza. Taki efekt bariery dielektrycznej związany jest z polaryzacją ładunku. Wartość ładunku przestrzennego zmienia się gwałtownie ze zmianą współczynnika alfa(-).