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1

Biomagnetic flow over a flat plate embedded by a magnetic dipole in a porous media

Ferdows Mohammad, Jumana Sadia Anjum

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 4

69--78

EN

The present study used a simplified axisymmetric biomagnetic fluid dynamics and porous mediamodel which includes FHD (Ferrohydrodynamics), porosity and inertia effects saturated by magnetic dipole to study the influences of the leading parameters on various flow variables along a flat plate.The governing equations are simplified and solved by finite difference approach. We clarify how the ferromagnetic interaction parameter, B and porosity,ε assumptions contribute in the bio-background of the problem of interest. Moreover, from the results of the flow profiles, accelerating and decelerating phenomena are noticed for B, and ε interaction.

2

Aeroacoustic analysis based on FW–H analogy to predict low-frequency in-plane harmonic noise of a helicopter rotor in hover

Suresh T., Szulc O., Flaszynski P.

Archives of Mechanics

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2022

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Vol. 74, nr 2-3

201--246

EN

The integral formulation of the Ffowcs-Williams and Hawkings (FW–H) analogy, developed by Farassat (known as Farassat’s formulation 1A), is implemented to study the sound generation and propagation of rotating slender bodies. The general post-processing numerical code utilizes the linear acoustic theory to predict the thickness and loading noise terms for bodies in subsonic motion. The developed numerical code is validated for elementary acoustic sources (rotating monopole and dipole) against analytical solutions. The validated code is then applied for prediction of lowfrequency in-plane harmonic noise (LF-IPH) of a model helicopter rotor of Sargent and Schmitz in a low-thrust hover with full-scale tip Mach number. The required loading distribution of the rotor blade is obtained with CFD (RANS) and Blade Element Momentum Theory (BEMT) methods and also validated against literature data. The developed acoustic code, supplemented by CFD and BEMT loading analyses, allows for a detailed comparison (thickness and loading, near- and far-field, etc.) of the LFIPH noise of a helicopter rotor in both, time and frequency domains. The predicted (FW–H) acoustic signals are compared not only with the reference code solutions, but also with the experimental data. Moreover, the paper quantifies the impact of computational grid density and time-step size (used by CFD and FW–H codes) on the final solution accuracy. Additionally, a simplified analytical code is developed (based on elementary dipole solutions, compact chord assumption and BEMT method) allowing for the initial loading noise analysis with highly reduced computational resources. The acquired results are fully compatible with the classical FW–H analysis in terms of the impact of the in-plane and out-of-plane forces on the generated noise. The FW–H code predictions of the acoustic pressure and its components are in satisfactory agreement with the reference and experimental data of Sargent and Schmitz.

3

Impact of a dipole on the phytoplankton community in a semi-enclosed basin of the southern Gulf of California, Mexico

Durán-Campos Elizabeth, Monreal-Gómez María Adela, Salas de León David Alberto, Coria-Monter Erik

Oceanologia

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2019

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No. 61 (3)

331--340

EN

The present study assesses the impact of a dipole on the abundance and distribution of phytoplankton groups as well as the chlorophyll-a concentration in the Bay of La Paz, Gulf of California, Mexico. Based on in situ observations obtained in a multidisciplinary research cruise during the summer of 2008, a mesoscale dipole (cyclone-anticyclone) was observed; the cyclone had ~25 km diameter and tangential speed of ~45 cm s-1, while the anticyclone had ~15 km diameter and tangential speed of ~40 cm s-1. Strong gradients in conservative temperature and density were observed between both structures, suggesting the presence of an oceanic thermohaline front. Differences in phytoplankton distribution showed minimum abundance of diatoms in the southern bay and close to Roca Partida Island, and maximum in the periphery in the northern cold core. The maximum abundance of dinoflagellates and silicoflagellates occurred at the frontal zone. The chlorophyll-a concentration was high in the region associated with the frontal zone. Although mesoscale eddies are ubiquitous processes in the Bay of La Paz, this study represents the first observational report of the impacts of a dipole on the phytoplankton structure and chlorophyll-a in the region. The observations presented here indicate the existence of a strong association between the mesoscale processes and the phytoplankton community in the study area. This study highlights the value of efforts to improve projections of physical forcing and its influence on the planktonic ecosystem.

4

Analiza skuteczności zakłóceń radiolokacyjnych systemu samoobrony statku powietrznego

Matuszewski J., Dudczyk J.

Elektronika : konstrukcje, technologie, zastosowania

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2015

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Vol. 56, nr 10

83-88

PL

Artykuł przedstawia krótką charakterystykę stosowanych metod zakłóceń radiolokacyjnych przy pomocy urządzeń instalowanych na platformach powietrznych. Opisano podstawowe parametry i właściwości nadajników zakłóceń i dipoli. Przedstawiono podstawowe zależności matematyczne wykorzystywane do oceny skuteczności zakłóceń radiolokacyjnych aktywnych i pasywnych. Obliczenia numeryczne skuteczności zakłóceń radiolokacyjnych wykonano dla kilku wariantów danych parametrów radaru i stacji zakłóceń. Wyniki obliczeń zilustrowano na odpowiednich wykresach. Skuteczna realizacja zakłóceń radiolokacyjnych w systemach walki elektronicznej, zarówno aktywnych jak i pasywnych, zależy od dokładnej znajomości parametrów zakłócanego radaru i nadajnika zakłóceń, wzajemnej odległości między nimi, przyjętego współczynnika degradacji, warunków propagacji fali elektromagnetycznej oraz zastosowanej metody zakłóceń.

EN

The article presents the short characteristics of radar jamming’s methods by using devices installed on the airplane board. Describes the basic jammers and chaffs parameters and their features. The basic mathematical formulas for calculating the effectiveness of active and passive radar jamming are presented. The numerical calculations of radar jamming’s effectiveness are made for some examples of different radar and jammers parameters. The results of these calculations are presented on the appropriate figures. The realization of the effective radar jamming in the electronic warfare system depends mainly on the precise knowledge of the radar and jammer’s technical parameters, the distance between, assumed value of the degradation coefficient, conditions of electromagnetic wave propagation and applied jamming method.

5

Multiclass classification strategy based on dipoles

Topczewska M.

Zeszyty Naukowe Politechniki Białostockiej. Informatyka

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2011

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Z. 8

79-90

EN

The problem of multiclass classification is considered and resolved through the approach based on dipoles. The found hyperplane separates objects from different classes cutting between them and not through their middle. The crux is to define a suitable functional, which is small on lines with good separation power and little damage, easy to calculate and to minimize. The numerical tests were performed and the criterion modified in a way that preserves the intention of finding cuts between classes, which separate as many data points as possible. The approach was tested on some synthetic data sets using a recursive implementation.

PL

W pracy rozpatrywane jest zagadnienie klasyfikacji w przypadku wieloklasowym oraz podejście oparte na dipolach. Poszukiwana hiperpłaszczyzna powinna rozdzielać obiekty należące do różnych klas, ale nie przecinając środka zadnej klasy. Zdefiniowano w tym celu odpowiedni funkcjonał, by przyjmował on małe wartości w przypadku prawidłowej klasyfikacji większości obiektów, był prosty do obliczenia i minimalizacji. Przeprowadzono testy numeryczne oraz dokonano modyfikacji kryterium, by znaleźć takie rozdzielenie klas, by odseparować możliwie dużo obiektów. Podejście było testowane na wybranych syntetycznych zbiorach danych przy wykorzystaniu implementacji w postaci wywołań rekurencyjnych.

6

Strategie klasyfikacji oparte na dipolach

Topczewska M., Frischmuth K.

Pomiary Automatyka Kontrola

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2010

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R. 56, nr 6

632-635

PL

W pracy przedstawiona została metoda klasyfikacji oparta na kryterium dipolowym. Przeprowadzone testy numeryczne skłoniły autorów do modyfikacji początkowego kryterium prezentowanego w pracy [1] w taki sposób, by znaleziona hiperpłaszczyzna separowała jak największą liczbę obiektów należących do różnych klas, nie rozdzielając obiektów z tej samej klasy. Nowe podejście zostało przetestowane na wygenerowanych zbiorach danych, a otrzymane wyniki pozwoliły na implementację w postaci wywołań rekurencyjnych.

EN

Finding a separating hyperplane for two classes by minimizing an error functional summing contributions for each poorly classified data point is by now common practice. Effective implementations in the framework of SVM or in terms of CPL functions are available and shown to work well for quite large sets of data. In this article a classification method based on dipoles is presented, which is a modification of a criterion given in [1]. We search for a hyperplane cutting between classes and not through their middle. The crux is to define a suitable functional, which is small on lines with good separation power and little damage, easy to calculate and to minimize. We perform numerical tests and modify the criterion in a way that preserves the intention of finding cuts between classes (and not through their middle), which separate as many data points as possible. However, we do not count (in integers), but weigh by taking the distance to the wrong side. The approach was tested on some synthetic data sets using a recursive implementation.

7

Dipolowe anteny planarne do zastosowań w standardzie Ultra-Wide Band (UWB)

Pergoł M., Zieniutycz W.

Elektronika : konstrukcje, technologie, zastosowania

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2007

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Vol. 48, nr 9

35-36

PL

Praca dotyczy przeglądu aktualnego stanu wiedzy z zakresu dipolowych anten planarnych przeznaczonych do obsługi standardu UWB (UltraWide Band). Omówiono pokrótce wymagania stawiane tego typu antenom. Następnie opisano budowę planarnych anten dipolowych, przedstawiono przykładowe rozwiązania konstrukcyjne oraz różne kształty ramion dipoli. Opisano również zagadnienia związane z zasilaniem tego typu anten, w tym przykłady stosowanych symetryzatorów, a także porównano parametry elektryczne omawianych anten.

EN

The paper presents shortly the state of art of planar dipole antennas for UWB applications. The requirements for such antennas are presented at the beginning of the paper. Next the structures of the planar dipoles are described as well as typical shapes of the antenna arms. The problem of the dipole feeding is also presented including a balun application. At the end the parameters of the exemplary antennas are shown and compared.

8

Zestaw anten pomiarowych do badania emisyjności urządzeń w zakresie częstotliwości od 30 do 1000 MHz

Tyrawa P., Kałuski M.

Telekomunikacja i Techniki Informacyjne

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2005

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nr 1-2

81-95

PL

Opisano metodykę projektowania i wzorcowania odbiorczych anten pomiarowych w zakresie częstotliwości od 30 do 1000 MHz, wykorzystywanych do badania niepożądanej emisyjności urządzeń, zgodnie z zaleceniami norm. Zaprezentowano zestaw anten opracowany i oferowany przez Instytut Łączności we Wrocławiu.

EN

The paper describes the design and calibration methodology for test antennas operating in the 30-1000 MHz frequency range that are used to measure undesirable device emissivity, according to standard recommendations. A set of antennas developed and offered by the National Institute of Telecommunications in Wrocław is presented.

9

Towards online use of body surface potentiaI mapping in clinical research

Stenroos M.

Biocybernetics and Biomedical Engineering

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2005

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Vol. 25, no. 4

69-75

EN

Body surface potential mapping (BSPM) is commonly used in clinical research. The next step is to bring BSPM to bedside use and also do basic data analysis during the measurement. In this online use, the measurement and analysis methods have to be particularly robust and easy to use. The signal quality should be good and the results repeatable. The BSPM measurement system used by Helsinki group consists of a single-use strip electrode set, a portable amplifier, and a laptop computer with docking station. In online analysis methods, easy display of potential maps plays a key role. The Helsinki group uses a 2D or 3D pseudocolor display with contour lines. In 3D visualization the isopotential surfaces are created by subdividing triangles. In software, the trade-off between reliability and incorporation of new ideas can be solved with interprocess communication. Potential uses of online BSPM are for ex ample guiding of a pacing catheter with dipole fitting. and detection of ischemia by visual analysis of ST-integral maps. Currently the bottleneck in Helsinki online BSPM system is the time-consuming preparation of the electrode set.

10

Contribution of dipolar species to the formation of local states for charge carriers in molecular materials

Sworakowski J., Nespurek S.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 2

163-171

EN

Effect of polar impurities on transport of charge carriers in non-polar molecular materials is reviewed. The presence of such species gives rise to structural traps. Calculations of local values of the polarization energy in the vicinity of dipolar defect show that traps as deep as several tenths of eV are created. If the polar impurity molecule can act as a trap itself, at high fields one may expect a dipole analogue of the Poole-Frenkel effect, the lowering of the trap depth following, however, a different dependence on the biasing electric field: Delta Et alpha F2/3. Moreover, the dipole-charge interactions contribute to the broadening of local transport states density in disordered materials.

11

TEM observations of faulted dipoles in deformed copper and copper alloys.

Niewczas M., Basinski Z.S., Basinski S.J., Embury J.D.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1244-1247

EN

The general properties of the deformation substructure are by now well-documented in the literature, but some of the more detailed properties still remain to be studied. In the present work we examine more closely the structures known as Frank dipoles or faulted dipoles, which are recognized in electron micrographs as faint lines terminating within the crystal and running in two <110> directions in the primary glide plane but not in the primary glide direction. The presence of faulted dipoles in formed materials was reported in some of the early transmission electron microscope (TEM) investigations of the 1960s and 1970s e.g., Cu single crystals [1,2], Ni-Co single crystals [3], Ag [4], Cu-2%Al single crystals [5], and in Ge [6]. In these studies, faulted dipoles were detected only in lightly deformed material in regions of the crystal relatively free of other dislocations. The present work takes advantage of the improved resolution available with today's electron microscopic techniques to examine the occurence of faulted dipoles in copper and copper alloy single crystals deformed to various stages in tension.