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Search results for: SPARSE AUTOREGRESSIVE MODELS
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Timber frame houses resistant to dynamic loads - seismic analysis
PublicationThe aim of the article is to present results of seismic analysis results of two real-sized timber frame buildings subjected to seismic excitations. The first model was insulated with mineral wool, the second one with polyurethane foam. Technology and specifications involved in both models construction is based on the previously conducted experimental research on timber frame houses, including wall panels tests, wall numerical models...
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Simulation model of IMS/NGN call processing performance
PublicationIn current telecommunications it is assumed that demands of the information society for quickly delivered services will be satisfied by the Next Generation Network (NGN) architecture, which includes IP Multimedia Subsystem (IMS) elements. To guarantee Quality of Service (QoS), proper design and dimensioning of NGN is absolutely necessary, for which appropriate models have to be proposed. As the NGN architecture is very complicated,...
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Problems of modelling toxic compounds emitted by a marine internal combustion engine in unsteady states
PublicationContemporary engine tests are performed based on the theory of experiment. The available versions of programmes used for analysing experimental data make frequent use of the multiple regression model, which enables examining effects and interactions between input model parameters and a single output variable. The use of multi-equation models provides more freedom in analysing the measured results, as those models enable simultaneous...
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Message Inter-Arrival and Inter-Departure Time Distributions in IMS/NGN Architecture
PublicationCurrently is it assumed that requirements of the information society for delivering multimedia services will be satisfied by the Next Generation Network (NGN) architecture, which includes elements of the IP Multimedia Subsystem (IMS) solution. In order to guarantee Quality of Service (QoS), NGN has to be appropriately designed and dimensioned. Therefore, proper traffic models should be proposed and applied. This requires determination...
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Aravind Ayyolath
PeopleI am interested in the biology of bacterial stress response and its growth under stress conditions. Our lab focuses on two aspects; protein folding and lipopolysaccharide biosynthesis and we address them with Escherichia coli models. Our recent studies have provided more evidence regarding several genes involved in the survival of bacteria under stress. I am also interested in disease biology and also in identifying proper therapeutic...
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Simulation of perovskite-based CuI/CH3NH3PbI3/TiO2 solar cell performance
Open Research DataThe presented data set is part of the theoretical research on novel thin-layer lead-halide perovskite solar cells with different inorganic transparent conductive oxides used as charge transport layers. In this study CuI/CH3NH3PbI3/TiO2 model structure (Model 1) was investigated by the use of the SCAPS-1D simulation method (https://scaps.elis.ugent.be/).
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Simulation of perovskite-based CuI/CH3NH3PbI3/SnO2 solar cell performance
Open Research DataThe presented data set is part of the theoretical research on novel thin-layer lead-halide perovskite solar cells with different inorganic transparent conductive oxides used as charge transport layers. In this study CuI/CH3NH3PbI3/SnO2 model structure (Model 2) was investigated by the use of the SCAPS-1D simulation method (https://scaps.elis.ugent.be/).
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Simulation of perovskite-based CuI/CH3NH3PbI3/ZnO solar cell performance
Open Research DataThe presented data set is part of the theoretical research on novel thin-layer lead-halide perovskite solar cells with different inorganic transparent conductive oxides used as charge transport layers. In this study CuI/CH3NH3PbI3/ZnO model structure (Model 3) was investigated by the use of the SCAPS-1D simulation method (https://scaps.elis.ugent.be/).
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Path Loss Modelling in the Untypical Outdoor Propagation Environments
PublicationIn the paper three ways of path loss modelling in the untypical outdoor environments are presented. The exemplary untypical outdoor environment is analyzed. The investigated environment is characterized, and the measurement campaign are shortly described. The following models have been analyzed: the COST231 Walfisch-Ikegami model, the modified COST231Walfisch-Ikegami model tuned on the basis of empirical data, and the empirical...
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On–line Parameter and Delay Estimation of Continuous–Time Dynamic Systems
PublicationThe problem of on-line identification of non-stationary delay systems is considered. The dynamics of supervised industrial processes are usually modeled by ordinary differential equations. Discrete-time mechanizations of continuous-time process models are implemented with the use of dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures mechanized in recursive forms are applied for simultaneous...
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Quality of service in optical burst switched networks
PublicationIn the paper analytical models of two service differentiation schemes for optical burst switched network: extended offset time based and PPS (Preemptive Priority Scheme) are revised. Also accordance of analytical models for those schemes is studied when complete class isolation is assumed. Furthermore authors introduce an analytical model which describes an effective degree of isolation when burst switched network employs both...
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Quality of service in optical burst switched networks
PublicationIn the paper analytical models of two service differentiation schemes for optical burst switched network: extended offset time based and PPS (Preemptive Priority Scheme) are revised. Also accordance of analytical models for those schemes is studied when complete class isolation is assumed. Furthermore authors introduce an analytical model which describes an effective degree of isolation when burst switched network employs both...
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New Tool for Examining QoS in the VToIP Service
PublicationThis paper is dedicated to the subject of measuring QoS in the Video Telephony over IP (VToIP) service. QoS measurement models in general and then models designed specifically for measuring QoS in the VToIP service are presented. A new numerical tool for examining the quality of VToIP video streams VToIP is described. The tool’s functionality is then put to the test in a number of analysis scenarios. The results and insights gained...
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EXPERIMENTS AND SIMULATIONS FOR LAPAROSCOPICVENTRAL HERNIA REPAIR IMPROVEMENT
PublicationThe authors conducted a wide experimental and numerical study in order to determine effective approaches in the laparoscopic VH repair. At first the study covered identification of mechanical properties of the abdominal fascia, implants, tacks and transabdominalsutures. Basis on these data, the one and two-dimensional mathematical models were formulated and a number of numerical static and dynamic analyses were carried out. Then...
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The effect of road restraint systems on the level of road safety - Polish experience
PublicationRoadside accidents happen when a vehicle runs off the road. The majority of these accidents are very severe because leaving the road is usually followed by hitting a solid obstacle (tree, pole, support, culvert front wall, barrier). Roadsides are some of the most important issues of road safety. They have been studied for years to identify roadside hazards and the effectiveness of road safety measures such as restraint systems....
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Dynamic Bayesian Networks for Symbolic Polyphonic Pitch Modeling
PublicationSymbolic pitch modeling is a way of incorporating knowledge about relations between pitches into the process of an- alyzing musical information or signals. In this paper, we propose a family of probabilistic symbolic polyphonic pitch models, which account for both the “horizontal” and the “vertical” pitch struc- ture. These models are formulated as linear or log-linear interpo- lations of up to fi ve sub-models, each of which is...
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Modelling the time-dependent behaviour of soft soils
PublicationTime-dependence of soft soils has already been thoroughly investigated. The knowledge on creep and relaxation phenomena is generally available in the literature. However, it is still rarely applied in practice. Regarding the organic soils, geotechnical engineers mostly base their calculations on the simple assumptions. Yet, as presented within this paper, the rate-dependent behaviour of soft soils is a very special and important...
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Data-driven, probabilistic model for attainable speed for ships approaching Gdańsk harbour
PublicationThe growing demand for maritime transportation leads to increased traffic in ports. From this arises the need to observe the consequences of the specific speed ships reach when approaching seaports. However, usually the analyzed cases refer only to the statistical evaluation of the studied phenomenon or to the empirical modelling, ignoring the mutual influence of variables such as ship type, length or weather conditions. In this...
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Modeling of entrained flow steam gasification of sewage sludge
PublicationProper management of sewage sludge becomes increasingly problematic due to legal requirements aiming at diminishing environmental impact, as well as rationalizing the utilization from the point of view of logistics. Steam gasification of sewage sludge can result in very good quality of the producer gas. So far, the works have been focused on the gasification in fixed bed gasifiers. However, this does not allow to take full advantage...
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Modele numeryczne uwzględniające tarczową pracę pokrycia dachowego z blach trapezowych
PublicationW artykule porównano wybrane sposoby uwzględniania w modelowaniu numerycznym tarczowej pracy pokrycia dachowego z blachy trapezowej, możliwe do zrealizowania w programie Autodesk Robot Structural Analysis Professional 2015, w celu oceny słuszności stosowania ich do obliczeń konstrukcji nośnej współpracującej z poszyciem z blachy trapezowej. Analizy przeprowadzono dla pojedynczej przepony. Za pomocą powłokowych elementów skończonych...
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Ocean mixed layer dynamics: high-resolution simulations of wind, wave and convective effects
Open Research DataThis dataset contains results of high-resolution numerical simulations of the ocean mixed layer (OML) forced by wind, waves and cooling from the atmosphere, i.e., under strongly turbulent, convective conditions. The goal is to provide detailed, three-dimensional information about OML circulation, turbulent kinetic energy, and temperature and salinity...
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Modeling SARS‐CoV‐2 proteins in the CASP‐commons experiment
PublicationCritical Assessment of Structure Prediction (CASP) is an organization aimed at advancing the state of the art in computing protein structure from sequence. In the spring of 2020, CASP launched a community project to compute the structures of the most structurally challenging proteins coded for in the SARS-CoV-2 genome. Forty-seven research groups submitted over 3000 three-dimensional models and 700 sets of accuracy estimates on...
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Dobór parametrów silnika indukcyjnego dużej mocy
PublicationW artykule przedstawiono trzy typy statycznych modeli matematycznych silników klatkowych oraz metodę estymacji parametrów, przy wykorzystaniu algorytmów genetycznych. Korzystając z kryteriów: suma kwadratów, suma wartości bez-względnych oraz całkowego, oceniono przydatność badanych modeli. Opracowane modele matematyczne zostały wykorzystane przy doborze algorytmów sterownia sterów strumieniowych. Po-kazano metodykę doboru parametrów...
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Application of fracture mechanics for energetic effects predictions while wood sawing
PublicationIn the classical approach, energetic effects (cutting forces and cutting power) of wood sawing process are generally calculated on the basis of the specific cutting resistance, which is in the case of wood cutting the function of more or less important factors. On the other hand, cutting forces (power) could be considered from a point of view of modern fracture mechanics. Cutting forces may be employed to determine not only toughness...
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Approximation of Message Inter-Arrival and Inter-Departure Time Distributions in IMS/NGN Architecture Using Phase-Type Distributions
PublicationCurrently it is assumed that requirements of the information society for delivering multimedia services will be satisfied by the Next Generation Network (NGN) architecture, which includes elements of the IP Multimedia Subsystem (IMS) solution. In order to guarantee Quality of Service (QoS), NGN has to be appropriately designed and dimensioned. Therefore, proper traffic models should be proposed and applied. This requires determination...
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ADT in mammography
PublicationWe discuss limitations of the known methods of IR imaging in diagnostics of breast cancer. In conclusion we show that for practical reasons one requires new approaches because the known methods based on simple observation of external temperature distribution are not fully effective. Even advanced pattern recognition could not help too much for static images. We ask the question: may active dynamic thermography, known in nondestructive...
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Visual Features for Improving Endoscopic Bleeding Detection Using Convolutional Neural Networks
PublicationThe presented paper investigates the problem of endoscopic bleeding detection in endoscopic videos in the form of a binary image classification task. A set of definitions of high-level visual features of endoscopic bleeding is introduced, which incorporates domain knowledge from the field. The high-level features are coupled with respective feature descriptors, enabling automatic capture of the features using image processing methods....
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On constitutive modeling for technical woven fabric
PublicationW pracy przestawiono kilka modeli konstytutywnych przyjmowanych do opisu zachowania się tkanin technicznych. Oprócz modeli zaczerpniętych z literatury autorzy prezentują własną koncepcje modelu stanowiąca rozszerzenie modelu sieci gęstej.This paper describes several types of the constitutive models used for the technical woven fabric description. Besides of the literatures examples of the constitutive models, the authors presented...
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Low harmonic multipulse voltage converters using coupled reactors
PublicationThis paper presents a novel approach to the multi pulse voltage converters (VC), especially voltage source inverters (VSI) and matrix converters (MC) based on several typical identical modules connected in parallel using coupled reactors. Such arrangements resulting in lower voltage distortions at extremely low switching frequency. The proposed arrangement was validated by simulation. Laboratory models of 18- and 24pulse 3-level...
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Numerical solution analysis of fractional point kinetics and heat exchange in nuclear reactor
PublicationThe paper presents the neutron point kinetics and heat exchange models for the nuclear reactor. The models consist of a nonlinear system of fractional ordinary differential and algebraic equations. Two numerical algorithms are used to solve them. The first algorithm is application of discrete Grünwald-Letnikov definition of the fractional derivative in the model. The second involves building an analog scheme in the FOMCON Toolbox...
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Improving the procedure of probabilistic load testing design of typical bridges based on structural response similarities
PublicationThis paper concerns load testing of typical bridge structures performed prior to operation. In-situ tests of a two-span post-tensioned bridge loaded with three vehicles of 38-ton mass each formed the input of this study. On the basis of the results of these measurements, an advanced FEM model of the structure was developed for which the sensitivity analysis was performed for chosen uncertainty sources. Three uncorrelated random...
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Numerical Model of Femur Part
PublicationThe aim of the study is to create a new more accurate method of femur part modelling by using the finite element method. According to this new method, a femur part is treated as a complex structure composed of trabecular bone (internal part) and cortical bone (external part). The internal part is modelled as a scaffold, thus the external part is modelled as a coat (i.e. covering). Applying the programme ABAQUS, there were created...
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublicationData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Detecting type of hearing loss with different AI classification methods: a performance review
PublicationHearing is one of the most crucial senses for all humans. It allows people to hear and connect with the environment, the people they can meet and the knowledge they need to live their lives to the fullest. Hearing loss can have a detrimental impact on a person's quality of life in a variety of ways, ranging from fewer educational and job opportunities due to impaired communication to social withdrawal in severe situations. Early...
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Assessing the attractiveness of human face based on machine learning
PublicationThe attractiveness of the face plays an important role in everyday life, especially in the modern world where social media and the Internet surround us. In this study, an attempt to assess the attractiveness of a face by machine learning is shown. Attractiveness is determined by three deep models whose sum of predictions is the final score. Two annotated datasets available in the literature are employed for training and testing...
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Chained machine learning model for predicting load capacity and ductility of steel fiber–reinforced concrete beams
PublicationOne of the main issues associated with steel fiber–reinforced concrete (SFRC) beams is the ability to anticipate their flexural response. With a comprehensive grid search, several stacked models (i.e., chained, parallel) consisting of various machine learning (ML) algorithms and artificial neural networks (ANNs) were developed to predict the flexural response of SFRC beams. The flexural performance of SFRC beams under bending was...
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Data-Driven Modeling of Mechanical Properties of Fiber-Reinforced Concrete: A Critical Review
PublicationFiber-reinforced concrete (FRC) is extensively used in diverse structural engineering applications, and its mechanical properties are crucial for designing and evaluating its performance. The compressive, flexural, splitting tensile, and shear strengths of FRCs are among the most important attributes, which have been discussed more extensively than other properties. The accurate prediction of these properties, which are required...
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A collection of directed graphs for the minimum cycle mean weight computation
Open Research DataThis dataset contains definitions of the 16 directed graphs with weighted edges that were described in the following paper: Paweł Pilarczyk, A space-efficient algorithm for computing the minimum cycle mean in a directed graph, Journal of Mathematics and Computer Science, 20 (2020), no. 4, 349--355, DOI: 10.22436/jmcs.020.04.08, URL: http://dx.doi.org/10.22436/jmcs.020.04.08 These...
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Expedited constrained multi-objective aerodynamic shape optimization by means of physics-based surrogates
PublicationIn the paper, computationally efficient constrained multi-objective design optimization of transonic airfoil profiles is considered. Our methodology focuses on fixed-lift design aimed at finding the best possible trade-offs between the two objectives: minimization of the drag coefficient and maximization of the pitching moment. The algorithm presented here exploits the surrogate-based optimization principle, variable-fidelity computational...
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Jakub Golik dr
PeopleJakub Golik currently works as a Research & Teaching Assistant at the Faculty of Management and Economics, Department of Entrepreneurship, Gdańsk University of Technology. Jakub does research in Utility-maximizing Models in Economy, Entrepreneurial Economics, Career Choice and Decision/Risk Theory. In his research he utilises mainly quantitative and experimental research methods including Conjoint Analysis and Structural Equation...
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Mariusz Franciszek Kaszubowski dr
PeopleBiogram Mariusz Kaszubowski works as Assistant Professor at the Department of Statistics and Econometrics, Faculty of Management and Economics, Gdansk University of Technology. He is teaching descriptive and mathematical statistics, as well social statistics and insurance statistics. He is lecturer of statistics in at postgraduate studies „Lean Six Sigma Black Belt”. He is a graduate of two majors: Management (specializing Insurance...
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Design of Cost-Efficient Optical Fronthaul for 5G/6G Networks: An Optimization Perspective
PublicationCurrently, 5G and the forthcoming 6G mobile communication systems are the most promising cellular generations expected to beat the growing hunger for bandwidth and enable the fully connected world presented by the Internet of Everything (IoE). The cloud radio access network (CRAN) has been proposed as a promising architecture for meeting the needs and goals of 5G/6G (5G and beyond) networks. Nevertheless, the provisioning of cost-efficient...
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Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder
PublicationAcoustic seafloor measurements with multibeam echosounders (MBESs) are currently often used for submarine habitat mapping, but the MBESs are usually not acoustically calibrated for backscattering strength (BBS) and cannot be used to infer absolute seafloor angular dependence. We present a study outlining the calibration and showing absolute backscattering strength values measured at a frequency of 150 kHz at around 10–20 m water...
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Changes in the addiction prevalence in Polish population between 1990-2019: Review of available data
PublicationThe 1989 collapse of the socialist political system in Poland initiated an avalanche of modifications regarding healthcare policy resulting with new institutions and programs dedicated to monitoring and preventing addiction. In the current article, we look at the available data allowing to track changes in (1) the prevalence of exposure to addictive substances and behaviors, and (2) changes of addictions prevalence in Poland...
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Analiza zachowań tłumu w multimedialnym systemie bezpieczeństwa
PublicationW niniejszym referacie zawarto opis metody detekcji zachowań tłumu na podstawie analizy obrazu. Koncepcja docelowego wykorzystania to wspomaganie pracy operatorów w systemach monitoringu, w szczególności podczas imprez masowych, np. na stadionach wyposażonych w wiele kamer. Celem opracowanej metody jest wykrywanie normalnych oraz potencjalnie niebezpiecznych zachowań tłumu, takich jak: panika, kierunkowy ruch masy ludzi, czy gromadzenie...
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Evidence for consolidation of neuronal assemblies after seizures in humans
PublicationThe establishment of memories involves reactivation of waking neuronal activity patterns and strengthening of associated neural circuits during slow-wave sleep (SWS), a process known as "cellular consolidation" (Dudai and Morris, 2013). Reactivation of neural activity patterns during waking behaviors that occurs on a timescale of seconds to minutes is thought to constitute memory recall (O'Keefe and Nadel, 1978), whereas consolidation...
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3D mesoporous α-Co(OH)2 nanosheets electrodeposited on nickel foam: A new generation of macroscopic cobalt-based hybrid for peroxymonosulfate activation
PublicationCobalt-based catalysts with high stability and facile recovery for heterogeneous peroxymonosulfate (PMS) activation are still rather sparse and therefore highly desirable. Herein, 3D mesoporous α-Co(OH)2 nanosheets was created on robust nickel foam (NF) via facile electrodeposition approach at 6 mA/cm2 for only 400 s. Almost complete removal of phenol can be achieved within 7 min with a degradation rate of 0.39 min−1, 2 times higher...
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Accelerated Parameter Tuning of Antenna Structures by Means of Response Features and Principal Directions
PublicationPopularity of numerical optimization has been steadily on the rise in the design of modern antenna systems. Resorting to mathematically rigorous parameter tuning methods is a matter of practical necessity as interactive techniques (e.g., parameter sweeping) are no longer adequate when handling several performance figures over multi-dimensional parameter spaces. The most common design scenarios involve local tuning since decent...
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5G/6G optical fronthaul modeling: cost and energy consumption assessment
PublicationIn fifth generation (5G) and the future beyond 5G (6G) radio access networks (RANs), the cost of fronthaul deployment is a main challenge for mobile network operators. Depending on different constraints, there are various solutions to deploy an efficient fronthaul. Fiber-optic-based fronthaul offers long-term support with regard to a rapid increase in capacity demands. When fiber connections, either point-to-point (P2P) or point-to-multipoint...
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The use of machine learning for face regions detection in thermograms
PublicationThe aim of this study is to analyse the methods of detecting characteristic points of the face in thermographic images. As part of the implementation an extensive analysis of scientific publications covering similar issues both for the analysis of images made in visible light and thermographic images was carried out. On the basis of this analysis, 3 models were selected and then they were implemented and tested on the basis of...