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Search results for: GRADIENT OPTIMIZATION
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FEM and experimental investigations of concrete temperature field in the massive stemwall of the bridge abutment
PublicationThe paper deals with the prediction of early-age concrete temperature of cast-in-place stemwall of the bridge abutment. The considered object is an arch bridge located in Gda´nsk. In the case of massive structures, it is particularly important to not exceed the temperature difference between the core and the concrete surface. Too high temperature gradient generates an increase in thermal stresses, what could be the reason of exceeding...
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Sea surface temperature distribution during upwelling along the Polish Baltic coast
PublicationAmong over 150 maps of sea surface temperature in the Polish Baltic coastal region derived from satellite data during the warm period of the year (April-October) in 2000-2002, 41 cases were noted where its distribution showed characteristic features indicating the occurrence of coastal upwelling. The fundamental parameters of range, probability of occurrence and temperature modification caused by water from deeper sea layers...
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An automatic selection of optimal recurrent neural network architecture for processes dynamics modelling purposes
PublicationA problem related to the development of algorithms designed to find the structure of artificial neural network used for behavioural (black-box) modelling of selected dynamic processes has been addressed in this paper. The research has included four original proposals of algorithms dedicated to neural network architecture search. Algorithms have been based on well-known optimisation techniques such as evolutionary algorithms and...
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Block Conjugate Gradient Method with Multilevel Preconditioning and GPU Acceleration for FEM Problems in Electromagnetics
PublicationIn this paper a GPU-accelerated block conjugate gradient solver with multilevel preconditioning is presented for solving large system of sparse equations with multiple right hand-sides (RHSs) which arise in the finite-element analysis of electromagnetic problems. We demonstrate that blocking reduces the time to solution significantly and allows for better utilization of the computing power of GPUs, especially when the system matrix...
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On the geometrically nonlinear vibration of a piezo-flexomagnetic nanotube
PublicationIn order to describe the behavior of thin elements used in MEMS and NEMS, it is essential to study a nonlinear free vibration of nanotubes under complicated external fields such as magnetic environment. In this regard, the magnetic force applied to the conductive nanotube with piezo-flexomagnetic elastic wall is considered. By the inclusion of Euler-Bernoulli beam and using Hamilton’s principle, the equations governing the system...
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Non-Contact Monitoring of ECG in the Home Environment—Selecting Optimal Electrode Configuration
PublicationCapacitive electrocardiography (cECG) is most often used in wearable or embedded measurement systems. The latter is considered in the paper. An optimal electrocardiographic lead, as an individual feature, was determined based on model studies. It was defined as the possibly highest value of the R-wave amplitude measured on the back of the examined person. The lead configuration was also analyzed in terms of minimizing its susceptibility...
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Quality Control of Bacterial Extracellular Vesicles with Total Protein Content Assay, Nanoparticles Tracking Analysis, and Capillary Electrophoresis
PublicationExtracellular vesicles (EVs) were isolated from Pectobacterium zantedeschiae culturing media using direct ultracentrifugation (UC), iodixanol cushion ultracentrifugation (ICUC), and iodixanol density gradient ultracentrifugation (IDGUC) techniques. The isolates were characterized with total protein content assay (bicinchoninic acid assay, BCA), nanoparticles tracking analysis (NTA), and capillary electrophoresis (CE). A satisfactory...
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Enhanced susceptibility to antifungal oligopeptides in yeast strains overexpressing ABC multidrug efflux pumps
PublicationPorównano podatność na działanie związków przeciwgrzybowych o strukturze oligopeptydowej oraz aminokwasowej szczepów Saccharomyces cerevisiae z usuniętymi genami kodującymi białka oporności wielolekowej oraz transformantów tych szczepów, zawierających geny CDR1, CDR2 lub MDR1, kodujące główne pompy wielolekowe Candida albicans. Rekombinowane szczepy nadprodukujące białka Cdr1p i Cdr2p wykazywały zwiększoną wrażliwość na wszystkie...
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Study of the Influence of Heat Convection Coefficient on Predicted Performance of a Large Tilting-Pad Thrust Bearing
PublicationPart of the heat generated by the shearing of the lubricating film during operation of a hydrodynamic bearing is transferred to the bearing components. In the case of the pad, which is usually fully submerged in the lubricating oil, heat is further transferred at the pad free walls to the oil by convection. This mechanism causes a thermal gradient in a pad and, consequently, its thermal deflection. In large hydrodynamic thrust...
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Application of Shape From Shading Technique for Side Scan Sonar Images
PublicationSide scan sonar (SSS) is one of the most widely used imaging systems in the underwater environment. It is relatively cheap and easy to deploy in comparison with more powerful sensors like multibeam echosounder or synthetic aperture sonar. Although, the SSS does not provide directly the seafloor bathymetry measurements. Its outputs are usually in a form of grey level acoustic images of seafloor. However, the analysis of such images...
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Magneto-thermal convection of low concentration nanofluids
PublicationThe main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried...
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Electronic structure of TbBa2Cu3O7
PublicationW pracy wykonano obliczenia kwantowomechaniczne struktury elektronowej hipotetycznego materiału TbBa2Cu3O7 (Dy123) metodą FP-LAPW (full potential - linearized augmented plane wave) w ramach formalizmu DFT (density functional theory) stosując przybliżenie GGA (generalized gradient approximation). Ze względu na silne oddziaływania korelacyjne elektronów 4f w atomie Tb zastosowano dodatkowo poprawkę kulombowską U w ramach modelu...
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Levels of 13 multi-class pesticide residues in Polish honeys determined by LC-ESI-MS/MS
PublicationLevels of 13 pesticides in 40 honey samples form Poland are reported. A rapid and sensitive method was developed for the LC-ESI-MS/MS determination of multi-class pesticide residues in honey samples. Liquid-liquid extraction (LLE) on a diatomaceous earth support (requiring the use of small amounts of organic solvent), followed by chromatographic separation on a C18 column and gradient elution were employed. The method quantifies...
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Tuning a Hybrid GPU-CPU V-Cycle Multilevel Preconditioner for Solving Large Real and Complex Systems of FEM Equations
PublicationThis letter presents techniques for tuning an accelerated preconditioned conjugate gradient solver with a multilevel preconditioner. The solver is optimized for a fast solution of sparse systems of equations arising in computational electromagnetics in a finite element method using higher-order elements. The goal of the tuning is to increase the throughput while at the same time reducing the memory requirements in order to allow...
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Reduction of the Velocity Impact on the Magnetic Flux Leakage Signal
PublicationThe velocity effect on the magnetic flux leakage (MFL) signal was investigated in this paper. Experiments were performed for velocity of the MFL tool within the range of 0–2 m/s. The velocity was not constant during each measurement to imitate real operational conditions of the MFL tool. Two components of the leakage were measured, i.e. the tangential to the motion direction (x) and the normal to the investigated surface (z). In...
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Surface effects of network materials based on strain gradient homogenized media
PublicationThe asymptotic homogenization of periodic network materials modeled as beam networks is pursued in this contribution, accounting for surface effects arising from the presence of a thin coating on the surface of the structural beam elements of the network. Cauchy and second gradient effective continua are considered and enhanced by the consideration of surface effects. The asymptotic homogenization technique is here extended to...
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Topological modifications for performance improvement and size reduction of wideband antenna structures
PublicationCompact antennas belong to the key components of modern communication systems. Their miniaturization is often achieved by introducing appropriate topological changes such as simple ground plane slots or tapered feeds. More sophisticated modifications are rarely considered in the literature because they normally lead to significant increase of the number of tunable parameters, which makes the antenna design process more challenging....
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Evaluating the influence of radiative heat flux on convective heat transfer from a vertical plate in air using an improved heating plate
PublicationThis article examines the influence of radiative heat flux on the accuracy of the results of free convective heat transfer in air. In order to carry out these tests, based on the experience gained during the operation of a plate heated on one side, compensated by a reverse heat loss flux counter-heater, a unique double-sided heating sandwich plate was designed and built, consisting of three thin epoxy resin plates reinforced with...
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Effect of surface on the flexomagnetic response of ferroic composite nanostructures; nonlinear bending analysis
PublicationOur analysis incorporates the geometrically nonlinear bending of the Euler-Bernoulli ferromagnetic nanobeam accounting for a size-dependent model through assuming surface effects. In the framework of the flexomagnetic phenomenon, the large deflections are investigated referring to von-Kármán nonlinearity. Employing the nonlocal effects of stress coupled to the gradient of strain generates a scale-dependent Hookean stress-strain...
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An isogeometric finite element formulation for boundary and shell viscoelasticity based on a multiplicative surface deformation split
PublicationThis work presents a numerical formulation to model isotropic viscoelastic material behavior for membranes and thin shells. The surface and the shell theory are formulated within a curvilinear coordinate system,which allows the representation of general surfaces and deformations. The kinematics follow from Kirchhoff–Love theory and the discretization makes use of isogeometric shape functions. A multiplicative split of the surface...
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A general theory for anisotropic Kirchhoff–Love shells with in-plane bending of embedded fibers
PublicationThis work presents a generalized Kirchhoff–Love shell theory that can explicitly capture fiber-induced anisotropy not only in stretching and out-of-plane bending, but also in in-plane bending. This setup is particularly suitable for heterogeneous and fibrous materials such as textiles, biomaterials, composites and pantographic structures. The presented theory is a direct extension of classical Kirchhoff–Love shell theory to incorporate...
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Active Kriging-based conjugate first-order reliability method for highly efficient structural reliability analysis using resample strategy
PublicationEfficient structural reliability analysis method is crucial to solving reliability analysis of complex structural problems. High-computational cost and low-failure probability problems greatly limit the efficiency in structural reliability analysis problems, causing the safety and reliability of the structure to be questioned. In this work, a highly efficient structural reliability analysis method coupling active Kriging algorithm...
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Colored Tattoo Ink Screening Method with Optical Tissue Phantoms and Raman Spectroscopy
PublicationDue to the increasing popularity of tattoos among the general population, to ensure their safety and quality, there is a need to develop reliable and rapid methods for the analysis of the composition of tattoo inks, both in the ink itself and in already existing tattoos. This paper presents the possibility of using Raman spectroscopy to examine tattoo inks in biological materials. We have developed optical tissue phantoms mimicking...
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Bicycle Traffic Model for Sustainable Urban Mobility Planning
PublicationModelling tools and transport models are required to assess the impact of measures for the effective planning of cycling routes in cities. This paper presents the methodology for developing a four-stage macroscopic model of bicycle traffic for the city of Gdynia, and its use in planning new bicycle routes, considering a modal shift. The model presented in this paper allows for the evaluation of the influence of the characteristics...
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Predictions of cervical cancer identification by photonic method combined with machine learning
PublicationCervical cancer is one of the most commonly appearing cancers, which early diagnosis is of greatest importance. Unfortunately, many diagnoses are based on subjective opinions of doctors—to date, there is no general measurement method with a calibrated standard. The problem can be solved with the measurement system being a fusion of an optoelectronic sensor and machine learning algorithm to provide reliable assistance for doctors...
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Acclimation of denitrifying activated sludge to a single vs. complex external carbon source during a start-up of sequencing batch reactors treating ammonium-rich anaerobic sludge digester liquors
PublicationIn this study, denitrification of ammonium- reach anaerobic sludge digester liquor was investigated during start-up periods of two laboratory- scale ‘‘fill-and-draw’’ reactors. One reactor was fed with a single carbon source (ethanol), whereas the other reactor was fed with a complex carbon source (fusel oil). During two acclimation experiments, the structure of microbial community involved in denitrification was analyzed using...
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Finger Vein Presentation Attack Detection Method Using a Hybridized Gray-Level Co-Occurrence Matrix Feature with Light-Gradient Boosting Machine Model
PublicationPresentation Attack Detection (PAD) is crucial in biometric finger vein recognition. The susceptibility of these systems to forged finger vein images is a significant challenge. Existing approaches to mitigate presentation attacks have computational complexity limitations and limited data availability. This study proposed a novel method for identifying presentation attacks in finger vein biometric systems. We have used optimal...
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Enhanced photocatalytic properties of lanthanide-TiO2 nanotubes: An experimental and theoretical study
PublicationA series of Er-, Yb-, Ho-, Tb-, Gd-, Pr-TiO2 nanotubes (RE-NTs) was prepared via an electrochemical method. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis absorption, scanning electron microscopy (SEM) and luminescent spectroscopy. The experiments demonstrated that toluene in the gas phase was successfully degraded under visible light (LEDs λmax = 465...
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Selection of Visual Descriptors for the Purpose of Multi-camera Object Re-identification
PublicationA comparative analysis of various visual descriptors is presented in this chapter. The descriptors utilize many aspects of image data: colour, texture, gradient, and statistical moments. The descriptor list is supplemented with local features calculated in close vicinity of key points found automatically in the image. The goal of the analysis is to find descriptors that are best suited for particular task, i.e. re-identification...
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Predicting Ice Phenomena in a River Using the Artificial Neural Network and Extreme Gradient Boosting
PublicationForecasting ice phenomena in river systems is of great importance because these phenomena are a fundamental part of the hydrological regime. Due to the stochasticity of ice phenomena, their prediction is a difficult process, especially when data sets are sparse or incomplete. In this study, two machine learning models—Multilayer Perceptron Neural Network (MLPNN) and Extreme Gradient Boosting (XGBoost)—were developed to predict...
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Infrared techniques for natural convection investigations in channels between two vertical, parallel, isothermal and symmetrically heated plates
PublicationThe effect of the gap width between two symmetrically heated vertical, parallel, isothermal plates on intensity of natural convective heat transfer in a gas (Pr = 0.71) was experimentally studied using the balance and gradient methods. In the former method heat fluxes were determined based on measurements of the voltage and electric current supplying the heaters placed inside the walls. In the latter, heat fluxes were calculated...
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Vertical Temperature Stratification of the Gulf of Gdansk Water
PublicationThe Baltic Sea is characterized by variable hydroacoustic conditions, which depend on hydrological conditions throughout the year. The temperature of the water is the factor that has the greatest impact on the changes in the speed of the sound in this basin. Even at a small depth, we can observe a large temperature gradient affecting the accuracy of the conducted research using hydroacoustic devices. A characteristic feature of...
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Self-Adaptive Mesh Generator for Global Complex Roots and Poles Finding Algorithm
PublicationIn any global method of searching for roots and poles, increasing the number of samples increases the chances of finding them precisely in a given area. However, the global complex roots and poles finding algorithm (GRPF) (as one of the few) has direct control over the accuracy of the results. In addition, this algorithm has a simple condition for finding all roots and poles in a given area: it only requires a sufficiently dense...
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Thermal buckling of functionally graded piezomagnetic micro- and nanobeams presenting the flexomagnetic effect
PublicationGalerkin weighted residual method (GWRM) is applied and implemented to address the axial stability and bifurcation point of a functionally graded piezomagnetic structure containing flexomagneticity in a thermal environment. The continuum specimen involves an exponential mass distributed in a heterogeneous media with a constant square cross section. The physical neutral plane is investigated to postulate functionally graded material...
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Application of an Electronic Nose Instrument to Fast Classification of Polish Honey Types
PublicationThe paper presents practical utilization of an electronic nose prototype, based on the FIGARO semiconductor sensors, in fast classification of Polish honey types—acacia flower, linden flower, rape, buckwheat and honeydew ones. A set of thermostating modules of the prototype provided gradient temperature characteristics of barbotage-prepared gas mixtures and stable measurement conditions. Three chemometric data analysis methods...
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Physics augmented classification of fNIRS signals
PublicationBackground. Predictive classification favours performance over semantics. In traditional predictive classification pipelines, feature engineering is often oblivious to the underlying phenomena. Hypothesis. In applied domains such as functional Near Infrared Spectroscopy (fNIRS), the exploitation of physical knowledge may improve the discriminative quality of our observation set. Aims. Give exemplary evidence that intervening the...
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Efficiency of Artificial Intelligence Methods for Hearing Loss Type Classification: an Evaluation
PublicationThe evaluation of hearing loss is primarily conducted by pure tone audiometry testing, which is often regarded as golden standard for assessing auditory function. If the presence of hearing loss is determined, it is possible to differentiate between three types of hearing loss: sensorineural, conductive, and mixed. This study presents a comprehensive comparison of a variety of AI classification models, performed on 4007 pure tone...
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ADAPTATION OF ENGINEERING FEA-BASED ALGORITHMS TO LCF FAILURE AND MATERIAL DATA PREDICTION IN OFFSHORE DESIGN
PublicationThere is an ever growing industrial demand for quantitative assessment of fatigue endurance of critical structural details. Although FEA-based calculations have become a standard in engineering design, problems involving the Low-To-Medium cycle range (101-104) remain challenging. This paper presents an attempt to optimally choose material data, meshing density and other algorithm settings in the context of recent design of the...
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Electronic structure and charge distribution in DyBa2Cu3O7: The ab initio approach
PublicationW pracy wykonano obliczenia kwantowomechaniczne struktury elektronowej nadprzewodzącego materiału DyBa2Cu3O7 (Dy123) metodą FP-LAPW (full potential - linearized augmented plane wave) w ramach formalizmu DFT (density functional theory) stosując przybliżenie GGA (generalized gradient approximation). Ze względu na silne oddziaływania korelacyjne elektronów 4f w atomie Dy zastosowano dodatkowo poprawkę kulombowską U w ramach modelu...
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The effect of reduced pressure on carbon dioxide flow boiling heat transfer in minichannels
Publication. In the paper presented are the results of the study on the effect of reduced pressure on flow boiling heat transfer data in minichannels as well as conventional ones. That effect renders that most of heat transfer correlations fail to return appropriate results of predictions. Mostly they have been developed for the reduced pressures from the range 0.1-0.3. The special correction has been postulated to the in-house model of flow...
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A Data Driven Model for Predicting RNA-Protein Interactions based on Gradient Boosting Machine
PublicationRNA protein interactions (RPI) play a pivotal role in the regulation of various biological processes. Experimental validation of RPI has been time-consuming, paving the way for computational prediction methods. The major limiting factor of these methods has been the accuracy and confidence of the predictions, and our in-house experiments show that they fail to accurately predict RPI involving short RNA sequences such as TERRA RNA....
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Forewarned Is Forearmed: Machine Learning Algorithms for the Prediction of Catheter-Induced Coronary and Aortic Injuries
PublicationCatheter-induced dissections (CID) of coronary arteries and/or the aorta are among the most dangerous complications of percutaneous coronary procedures, yet the data on their risk factors are anecdotal. Logistic regression and five more advanced machine learning techniques were applied to determine the most significant predictors of dissection. Model performance comparison and feature importance ranking were evaluated. We identified...
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Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
PublicationThis paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response...
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Effects of Noncontact Shoulder Tool Velocities on Friction Stir Joining of Polyamide 6 (PA6)
PublicationIn this study, the effects of the traverse and rotational velocities of the noncontact shoulder tool on the heat generation and heated flux during the friction stir joining of high-density polyamide 6 (PA6) polymer were investigated. The computational fluid dynamics (CFD) method was employed to simulate the thermomechanical phenomena during the friction stir joining (FSJ) process of PA6. A developed model was used to consider the...
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Resistance of Escherichia coli and Enterococcus spp. to selected antimicrobial agents present in municipal
PublicationIn this study, the susceptibility to erythromycin (E) and to trimethoprim/sulfamethoxazole (SXT) among isolates of Enterococcus spp. and Escherichia coli was tested, respectively. Both fecal indicators were detected and isolated from raw(RW) and treated wastewater (TW) as well as from samples of activated sludge (AS) collected in a local wastewater treatment plant (WWTP). Biodiversity of bacterial community in AS was also monitored...
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Hierarchia czynników wpływu w diagnostyce komponentów stalowych metodą statycznego pola rozproszonego
PublicationWśród technik badań nieniszczących obiektów stalowych (NDT) szczególną rolę pełnią techniki elektromagnetyczne, jako relatywnie tanie, czyste, szybkie i adaptowalne. Mają one jednak istotne ograniczenia, o których wydają się zapominać praktycy promujący tzw. metodę magnetycznej pamięci metali (ang. magnetic metal memory, MMM). Szczególnie dyskusyjna jest postulowana przez nich możliwość ilościowej korelacji charakterystyk pola...
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3D seafloor reconstruction using data from side scan and synthetic aperture sonar
PublicationSide scan and synthetic aperture sonars are widely used imaging systems in the underwater environment. They are relatively cheap and easy to deploy, in comparison with more powerful sensors, like multibeam echosounders. Although side scan and synthetic aperture sonars does not provide seafloor bathymetry directly, their records are finally related to seafloor images. Moreover, the analysis of such images performed by human eye...
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Antibiotic resistance in wastewater, does the context matter? Poland and Portugal as a case study
PublicationAntibiotic resistance has been considered a major human health threat that may endanger the success of medicine. Recent studies have unveiled worldwide asymmetries of antibiotic resistance occurrence, being factors as diverse as climate, socioeconomic, or antibiotic use possible drivers of such asymmetric distribution. In Europe, where clinical antibiotic resistance is surveyed for more than 20 years, the European Center for Disease...
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Ciliated protozoa in the impact zone of the Uzhgorod treatment plant
PublicationThis paper presents the results of studies on the Uzh River (Ukraine, Zakarpattia Oblast) near the effluent point of a sewage treatment plant in Uzhgorod. The samples were taken at various sites of the treatment plant along the stages of purification process, as well as in the river, at a number of different points above and below the wastewater discharge. At each of these objects, the temperature...
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Personalized prediction of the secondary oocytes number after ovarian stimulation: A machine learning model based on clinical and genetic data
PublicationControlled ovarian stimulation is tailored to the patient based on clinical parameters but estimating the number of retrieved metaphase II (MII) oocytes is a challenge. Here, we have developed a model that takes advantage of the patient’s genetic and clinical characteristics simultaneously for predicting the stimulation outcome. Sequence variants in reproduction-related genes identified by next-generation sequencing were matched...