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Search results for: FREQUENCY SELECTIVE SURFACE
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Frequency Selective Surface Based MIMO Antenna Array for 5G Millimeter-Wave Applications
PublicationAbstract: In this paper a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2×2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabri-cated on Rogers RT/Duroid high frequency substrate...
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Novel Versatile Topologies and Design Optimization of Wide-Bandstop Frequency Selective Surfaces for X-Band, Ku-Band and Millimeter-Wave Applications
PublicationNovel designs of frequency selective surface (FSS) are presented for wideband applications in X, Ku and mmWave (millimeter Wave) bands. Two identical metallic layers of FSS are imprinted on both sides of the RO4003 substrate. The geometry parameters are optimized to maximize the bandstop at the specified in-band maximum transmission level of –10 dB; satisfaction of the latter condition is enforced through appropriate formulation...
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Accurate Modeling of Frequency Selective Surfaces Using Fully-Connected Regression Model with Automated Architecture Determination and Parameter Selection Based on Bayesian Optimization
PublicationSurrogate modeling has become an important tool in the design of high-frequency structures. Although full-wave electromagnetic (EM) simulation tools provide an accurate account for the circuit characteristics and performance, they entail considerable computational expenditures. Replacing EM analysis by fast surrogates provides a way to accelerate the design procedures. Unfortunately, modeling of microwave passives is a challenging...
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Surface engineering of graphene oxide membranes for selective separation of perfluorooctanoic acids
PublicationPerfluoroalkyl compounds (PFCs) are environmental toxicants and their widespread detection and accumulation in the environment can be detrimental to the ecosystem. In this study, surface charge of GO membranes was engineered to enhance selectivity of graphene oxide (GO) membranes and for the removal of perfluorooctanoic acid (PFOA ∼400 Da) in real concentration ranges in wastewater streams. The structure and physicochemical properties...
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Reduction of Influence of the High-Frequency Noise on the Results of Surface Topography Measurements
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Selective Introduction of Hydroxyl Groups Onto the Surface of Carbon Nanotubes via Chlorination and Hydrolytic Dechlorination
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Cylindrical surface irregularities presented by frequency spectra of relative tool displacement to the workpiece
PublicationW pracy przedstawiono częstotliwościowe składowe nierówności powierzchni toczonych. Ponieważ nierówności mają charakter szerokopasmowy, trudny do wartościowania parametrami normatywnymi, zastosowano ich analizę amplitudowo-częstotliwościową, opartą na szybkiej transformacie Fouriera. Zaproponowano oryginalny układ pomiaru sygnału przemieszczeń narzędzia względem przedmiotu dla charakteryzowania nierówności wzdłużnych. Dla generowania...
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Cylindrical surface irregularities presented by frequency spectra of relative tool displacement to the workpiece
PublicationW pracy przedstawiono częstotliwościowe składowe nierówności powierzchni toczonych. Ponieważ nierówności mają charakter szerokopasmowy, trudny do wartościowania parametrami normatywnymi, zastosowano ich analizę amplitudowo-częstotliwościową, opartą na szybkiej transformacie Fouriera. Zaproponowano oryginalny układ pomiaru sygnału przemieszczeń narzędzia względem przedmiotu dla charakteryzowania nierówności wzdłużnych. Dla generowania...
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Conditions for measurement, analog-to-digital conversion and frequency analysis of irregularities of profile surface
PublicationPrzedstawiono uwarunkowania pomiaru, przetwarzania analogowo-cyfrowego i analizy częstotliwościowej nierówności powierzchni toczonych dla celów rozpoznawania ich głównych składowych. Przedstawiono ograniczenia w pomiarze igłą, która odwzorowuje nierówności poprzeczne. Podano zależności parametrów pomiaru cyfrowego nierówności warunkujące zakresy ich rozpatrywania. Dla wartości przedziału próbkowania, dla którego nie jest spełnione...
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Determinants of the surface quality, density and dimensional correctness in selective laser melting of the Ti-13Zr-13Nb alloy
PublicationSelective laser melting is widely used for custom-designed elements. Successful manufacturing depends on laser treatment parameters and material features. This research aimed to determine the effects of laser power, scan time and hatch distance on surface quality, relative density and dimensional precision for cuboids made of the Ti-13Zr-13Nb alloy. The influence of energy density, energy flux and pre-heating was seen to be decisive...
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Magnetic field maps of an astable multivibrator in frequency range from 30 MHz to 3 GHz – selective detection
Open Research DataThe data presents a result of near field measurements of electromagnetic emissions radiated from the PCB of a small electronic device. An efficient method of modelling the magnetic and electric field emissions is the measurements in the near field using electric and magnetic probes. The attached files contain magnetic field maps created on based measurements...
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Evaluation of Surface Topography after Face Turning of CoCr Alloys Fabricated by Casting and Selective Laser Melting
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Proposal of frequency‐based decomposition approach for minimization of errors in surface texture parameter calculation
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Feature-Based Characterisation of Turned Surface Topography with Suppression of High-Frequency Measurement Errors
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Proposals of Frequency-Based and Direction Methods to Reduce the Influence of Surface Topography Measurement Errors
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Laser-textured cross-hatched surface topography analysis with evaluation of high-frequency measurement noise
PublicationThe precision of surface roughness determination using ISO 25178 parameters relies on various factors that directly impact the measurement process. In industry applications, the contactless roughness measurement reduces data collection time. However, it introduces several potential errors, including those stemming from the environment. One of the main types of errors encountered during topography analysis is measurement noise,...
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The features of steel surface hardening with high energy heating by high frequency currents and shower cooling
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Numerical Modeling of Steel Surface Hardening in the Process of High Energy Heating by High Frequency Currents
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Efficiency of hybrid equipment combining operations of surface hardening by high frequency currents and abrasive grinding
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Application of Time-Frequency Analysis of Acoustic Signal to Detecting Flat Places on the Rolling Surface of a Tram Wheel
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Selection of Methods of Surface Texture Characterisation for Reduction of the Frequency-Based Errors in the Measurement and Data Analysis Processes
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Suppression of the High-Frequency Errors in Surface Topography Measurements Based on Comparison of Various Spline Filtering Methods
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Experimental investigation of selective laser melting parameters for higher surface quality and microhardness properties: taguchi and super ranking concept approaches
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Formation of high-carbon abrasion-resistant surface layers when high-energy heating by high-frequency currents
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Multifrequency Nanoscale Impedance Microscopy (m-NIM): A novel approach towards detection of selective and subtle modifications on the surface of polycrystalline boron-doped diamond electrodes
PublicationIn this paper, we describe the modification of Nanoscale Impedance Microscopy (NIM), namely, a combination of contact-mode atomic force microscopy with local impedance measurements. The postulated approach is based on the application of multifrequency voltage perturbation instead of standard frequency-by-frequency analysis, which among others offers more time-efficient and accurate determination of the resultant impedance spectra...
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Fast Fourier Transform detection and reduction of high-frequency errors from the results of surface topography profile measurements of honed textures
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Improved Procedures for Feature-Based Suppression of Surface Texture High-Frequency Measurement Errors in the Wear Analysis of Cylinder Liner Topographies
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Robert Bogdanowicz dr hab. inż.
PeopleRobert Bogdanowicz received his Ph.D. degree with honours in Electronics from the Gdansk University of Technology. He worked as a post-doc researcher in Ernst-Moritz-Arndt-Universität Greifswald Institut für Physik. He has initiated optical emission imaging of muti-magnetron pulsed plasma and contributed to the development of antibacterial implant coatings deposited by high-power impulse magnetron sputtering. He moved back to...
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An Analysis of Periodic Arrangements of Cylindrical Objects of Arbitrary Convex Cross Sections with the Use of Field Matching Method
PublicationA problem of electromagnetic wave scattering from multilayered frequency selective surfaces is presented. Each surface is composed of periodically arranged cylindrical posts of arbitrary convex cross-section. The method of analysis is based on the direct field matching technique for a single cell, and the transmission matrix method with the lattice sums technique for periodic arrangement of scatterers.
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Pulsed UV-irradiated Graphene Sensors for Ethanol Detection at Room Temperature
PublicationA graphene-based gas sensor fabricated in a FET (GFET) configuration and its sensitivity towards ethanol and methane is reported. Detection of ethanol at the level of 100 ppm was observed under pulsed UV irradiation and after cleaning by UV light in the N2 ambient. Reduction of the frequency of UV irradiation pulses resulted in increased changes in sensor resistance in the presence of ethanol. Improved sensing behavior was ascribed...
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Plasma-Based Deposition and Processing Techniques for Optical Fiber Sensing
PublicationPlasma-based techniques are widely applied for well-controlled deposition, etching or surface functionalization of a number of materials. It is difficult to imagine fabrication of novel microelectronic and optoelectronic devices without using plasma-enhanced deposition of thin films, their selective etching or functionalization of their surfaces for subsequent selective binding of chemical or biological molecules. Depending on...
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Data-Driven Surrogate-Assisted Optimization of Metamaterial-Based Filtenna Using Deep Learning
PublicationIn this work, a computationally efficient method based on data driven surrogate models is pro-posed for the design optimization procedure of a Frequency Selective Surface (FSS)-based filtering antenna (Filtenna). A Filtenna acts as a as module that simultaneously pre-filters unwanted sig-nals, and enhances the desired signals at the operating frequency. However, due to a typically large number of design variables of FSS unit elements,...
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A Study of Mutual Coupling Suppression between Two Closely Spaced Planar Monopole Antenna Elements for 5G New Radio Massive MIMO System Applications
Publication5G NR (new radio) introduces the concept of massive MIMO (multiple-input-multiple-output) technology, in which a larger number of antenna arrays are installed on the transceiver. Due to the increased number of antenna elements allocated close to each other (approximately at half-wavelength distance), mutual coupling becomes a serious problem leading to performance degradation of the MIMO communication system. In this communication,...
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Selective Laser Melting of Ti Alloy for Manufacturing The Prosthetic Elements
PublicationThe selective laser melting (SLM) is the additive manufacturing method of custom-designed parts. The used materials and the applications are various, including medicine. The titanium and its alloys are materials for which the dimensional quality, surface smoothness and no or extremely low porosity are difficult to reach. In this paper, the successful attempt to obtain by SLM the individually designed prosthetic bridges is described....
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Lead(II)-selective ionophores for ion-selective electrodes: A review
PublicationIn potentiometry, high selectivity of the ion-selective membranes must be assured in order to reliably measure various analytes in clinical, industrial and environmental samples. Due to the toxic nature of lead(II) it is important to monitor Pb2+ distribution in natural waters. This may be achieved by implementation of ion-selective electrodes (ISEs) with high selectivity towards lead(II) and low detection limit. A great number...
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Nitrogen sorption isotherm for V2CTx
Open Research DataData of points for nitrogen sorption isotherm for sample V2CTx (only sorption branch). The V2CTx was prepared via selective etching of aluminium from MAX matrice V2AlC using 50% HF for 96 h at room temperature.
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THE USE OF THE Ti-13Zr-13Nb ALLOY POWDER FOR MANUFACTURING OF PROSTHETIC PARTS BY SELECTIVE LASER MELTING
PublicationThe 3D printing is a manufacturing technique belonging to the additive methods able to prepare the designed parts for various purposes. The present reasearch was aimed to fabricate the prosthetic foundations and bridges made of the new Ti-13Zr-13Nb alloy by the selective laser melting (SLM) of a metal powder. The scanning electron examinations and micro scanning tomography were used to investigate the surface quality and intrinsic...
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XRD data of V2AlC, Mo3AlC2, Mo3CTx and V2AlCTx
Open Research DataRaw data for XRD diffractograms of MAX phases: V2AlC and Mo3AlC2 and corresponding MXenes after selective etching of Al.
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Selective jamming of OFDM transmission in NB-IoT radio interface
PublicationThe paper presents the concept of smart jamming, which involves selective interference aimed at critical components of the OFDM signal. Research verifying the feasibility of this type of electronic attack are described. A realized testbed for jamming real NB-IoT signals in a downlink is presented. The test results demonstrate the feasibility of realizing selective jamming and its greater effectiveness compared to barrage interference.
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Generation-recombination and 1/f noise in carbon nanotube networks
PublicationThe low-frequency noise is of special interest for carbon nanotubes devices, which are building blocks for a variety of sensors, including radio frequency and terahertz detectors. We studied noise in as-fabricated and aged carbon nanotube networks (CNNs) field-effect transistors. Contrary to the majority of previous publications, as-fabricated devices demonstrated the superposition of generation-recombination (GR) and 1/f noise...
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Cancer-selective, single agent chemoradiosensitising gold nanoparticles
PublicationTwo nanometre gold nanoparticles (AuNPs), bearing sugar moieties and/or thiol-polyethylene glycol-amine (PEG-amine), were synthesised and evaluated for their in vitro toxicity and ability to radiosensitise cells with 220 kV and 6 MV X-rays, using four cell lines representing normal and cancerous skin and breast tissues. Acute 3 h exposure of cells to AuNPs, bearing PEG-amine only or a 50:50 ratio of alpha-galactose derivative and...
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Potentiometric Solid-Contact Ion-Selective Electrode for Determination of Thiocyanate in Human Saliva
PublicationA new solid-contact potentiometric ion-selective electrode for the determination of SCN− (SCN-ISE) has been described. Synthesized phosphonium derivative of calix[4]arene was used as a charged ionophore. The research included selection of the ion-selective membrane composition, determination of the ISEs metrological parameters and SCN-ISE application for thiocyanate determination in human saliva. Preparation of the ISEs included...
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Selective Harmonic Elimination PWM For a Cascaded Multi-level Inverter
PublicationThis paper deals with the selective harmonic elimination pulse width modulation (SHE-PWM) technique. This technique is used for the elimination of selected dominant low order harmonics in the multi-level inverter output voltage. The presence of these harmonics is the essential drawback of such kind of inverters; especially when it is used for the control of different AC drivers. The SHE-PWM is based...
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Molecular Umbrellas Modulate the Selective Toxicity of Polyene Macrolide Antifungals
PublicationAntifungal polyene macrolide antibiotics Amphotericin B (AmB) and Nystatin (NYS) were conjugated through the ω-amino acid linkers with diwalled “molecular umbrellas” composed of spermidine-linked deoxycholic or cholic acids. The presence of “umbrella” substituents modulated biological properties of the antibiotics, especially their selective toxicity. Some of the AmB-umbrella conjugates demonstrated antifungal in vitro activity...
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Effects of Micro-Arc Oxidation Process Parameters on Characteristics of Calcium-Phosphate Containing Oxide Layers on the Selective Laser Melted Ti13Zr13Nb Alloy
PublicationTitania-based films on selective laser melted Ti13Zr13Nb have been formed by micro-arc oxidation (MAO) at different process parameters (voltage, current, processing time) in order to evaluate the impact of MAO process parameters in calcium and phosphate (Ca + P) containing electrolyte on surface characteristic, early-stage bioactivity, nanomechanical properties, and adhesion between the oxide coatings and substrate. The surface...
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Solid-contact lead(II) ion-selective electrodes for potentiometric determination of lead(II) in presence of high concentrations of Na(I), Cu(II), Cd(II), Zn(II), Ca(II) and Mg(II)
PublicationLead and its compounds are a serious threat to the environment. Monitoring of this toxic heavy metal is a driving force for the continuous development of novel lead(II) ionophores to be applied in ion-selective electrodes. In this work a highly selective lead(II) ionophore, namely 25,26,27,28-tetrakis(piperidinylthiocarbonylmethylene)-p-tert-butylcalix[4]arene, was used in solid-contact ion-selective electrodes for determination...
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The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels
PublicationIn this study, the fractal dimension of fatigue fracture surfaces is investigated in order to find an alternative failure loading indicator. Some of many metrological factors are generalized by reducing the fracture surface structure to one factor and develop an entire fracture surface procedure by analyzing the impact of surface slope and calculation resolution. Three notched geometries are studied under cyclic bending-torsion:...
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Influence of laser melting on surface layer properties of titanium alloy Ti6Al4V
PublicationIn time of rapid technology and medicine progress, implants are becoming more widely used in the human body, ranging from dental implants, stabilizing plates, screws, orthopaedic prostheses. For example, there are many types of hip prostheses used for hip replacement as well as various types of materials used for these orthopaedic prostheses. Properties of titanium alloys used in hip prostheses combined with good strength properties,...
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Reduced-Cost Design Optimization of High-Frequency Structures Using Adaptive Jacobian Updates
PublicationElectromagnetic (EM) analysis is the primary tool utilized in the design of high-frequency structures. In vast majority of cases, simpler models (e.g., equivalent networks or analytical ones) are either not available or lack accuracy: they can only be used to yield initial designs that need to be further tuned. Consequently, EM-driven adjustment of geometry and/or material parameters of microwave and antenna components is a necessary...
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Potentiometric sensor containing set of ion selective electrodes with lipid modified membranes for quality assessment of tested non-alcoholic beverages
PublicationPotentiometric sensors may be a good tool for fast quality control of commercial drinks. In this work, such a sensor, containing a set of ion-selective electrodes with lipid-modified membranes (benzylhexadecyldimethylammonium chloride monohydrate, hexadecylamine, 1-dodecanol, elaidic acid, cholesterol) was used for discrimination and quality control of non-alcoholic beverages, mainly composed of sugar and citric acid. It was found...