Filters
total: 7106
-
Catalog
- Publications 5714 available results
- Journals 23 available results
- Conferences 21 available results
- Publishing Houses 1 available results
- People 72 available results
- Projects 1 available results
- e-Learning Courses 81 available results
- Events 5 available results
- Open Research Data 1188 available results
displaying 1000 best results Help
Search results for: time-frequency domain
-
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,...
-
Improving sensitivity of residual current transformers to high frequency earth fault currents
PublicationFor protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed...
-
Cezary Czaplewski prof. dr hab.
People -
Coupling of Blood Pressure and Subarachnoid Space Oscillations at Cardiac Frequency Evoked by Handgrip and Cold Tests: A Bispectral Analysis
PublicationThe aim of the study was to assess blood pressure–subarachnoid space (BP–SAS) width coupling properties using time–frequency bispectral analysis based on wavelet transforms during handgrip and cold tests. The experiments were performed on a group of 16 healthy subjects (F/M; 7/9) of the mean age 27.2 ± 6.8 years and body mass index of 23.8 ± 4.1 kg/m². The sequence of challenges was first handgrip and then cold test. The handgrip...
-
Multiple-channel frequency-adaptive active vibration control using SONIC
PublicationSONIC (self-optimizing narrowband interference canceller) is an acronym of a new approach to rejection of sinusoidal disturbances acting at the output of a discretetime stable linear plant with unknown and possibly timevarying dynamics. The paper presents two frequency-adaptive extensions of the multivariate SONIC algorithm. The efficacy of the proposed solutions is tested using our laboratory-scale active vibration control plant.
-
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...
-
Reshaping of Coastlines as the Beginning of Urban Structures Changes in North Poland
PublicationThis article discusses the problem of strategies concerning the processes of re-shaping the Baltic Sea southern coastline applied recently in North Poland. The undertaken research is an attempt to identify the relationship between the modifications of coastline forms and the positive changes of urban structures. It can be seen that these modifications are needed because of the problems of existing shoreline erosion. It can be also...
-
Influence of Thermal Imagery Resolution on Accuracy of Deep Learning based Face Recognition
PublicationHuman-system interactions frequently require a retrieval of the key context information about the user and the environment. Image processing techniques have been widely applied in this area, providing details about recognized objects, people and actions. Considering remote diagnostics solutions, e.g. non-contact vital signs estimation and smart home monitoring systems that utilize person’s identity, security is a very important factor....
-
Continuous wave sonar with hyperbolic frequency modulation keyed by pseudo-random sequence
PublicationA CW FM type sounding signal is used in the classical solution of silent sonar. While the signal provides a relatively simple implementation of digital signal processing, and ensures good detection conditions, unfortunately, in the presence of the Doppler effect, distance measurement results tend to be wrong. This is due to the fact that the received signal’s instantaneous frequency value is dependent both on the distance to the...
-
Nonreciprocal cavities and the time-bandwidth limit: comment
PublicationIn their paper in Optica 6, 104 (2019), Mann et al. claim that linear, time-invariant nonreciprocal structures cannot overcome the time-bandwidth limit and do not exhibit an advantage over their reciprocal counterparts, specifically with regard to their time-bandwidth performance. In this Comment, we argue that these conclusions are unfounded. On the basis of both rigorous full-wave simulations and insightful physical justifications,...
-
Highly-Miniaturized Microfluidically-Based Frequency Reconfigurable Antenna Diplexer Employing Half-Mode SIRW
PublicationThis article introduces a super-miniaturized frequency reconfigurable antenna diplexer based on microfluidic techniques. The proposed structure is developed using a half-mode substrate-integrated rectangular waveguide (HMSIRW). The antenna architecture consists of two HMSIRW cavities loaded with L-shaped slots, which are excited by two microstrip feedlines to realize two distinct radiating frequency bands. The footprint of the...
-
On the deformation and frequency analyses of SARS-CoV-2 at nanoscale
PublicationThe SARS-CoV-2 virus, which has emerged as a Covid-19 pandemic, has had the most significant impact on people's health, economy, and lifestyle around the world today. In the present study, the SARS-CoV-2 virus is mechanically simulated to obtain its deformation and natural frequencies. The virus under analysis is modeled on a viscoelastic spherical structure. The theory of shell structures in mechanics is used to derive the governing...
-
Cosmic-Time Quantum Mechanics and the Passage-of-Time Problem
PublicationA new dynamical paradigm merging quantum dynamics with cosmology is discussed.
-
Substrate Integrated Waveguide-Based Frequency-Tunable Self-Octaplexing Antenna
PublicationThis communication presents the first-ever substrate integrated waveguide (SIW)-based frequency-tunable self-octaplexing antenna (SOA) for wireless communication. The structure is arranged by implementing eight distinct patches with planar 50-ohm feedlines at the top of the SIW cavity, which realize eight distinct resonant frequencies. Independent tuning of each resonant frequency is achieved by incorporating appropriately allocated...
-
Analysis of inductive power transfer systems for variable air gap and voltage supply frequency
PublicationThe paper describes an IPT system, by which electrical energy may be transmitted through a large air gap between coils without electrical connection. It presents theoretical and simulation analysis of IPT, which allows for supplying a receiver in the conditions of slow, in relation to the dynamics of power supply, changes in dimension of the air gap. The influence of frequency characteristics of the system on the possible selection...
-
Understanding the containment of public spaces: upgrading public domain
Publication -
Internet of Robotic Things: Its Domain, Methodologies, and Applications
Publication -
Application of gaze tracking technology to quality of experience domain
PublicationA new methodological approach to study subjective assessment results employing gaze tracking technology is shown. Notions of Human-Computer Interaction (HCI) and Quality of Experience (QoE) are shortly introduced in the context of their common application. Then, the gaze tracking system developed at the Multimedia Systems Department (MSD) of Gdansk University of Technology (GUT) is presented. A series of audio-visual subjective...
-
Numerical conditioning of delta-domain Lyapunov and Riccati equations
PublicationW pracy rozważono problem uwarunkowania dyskretno czasowych równań Lapunowa oraz równań Riccatiego - to znaczy problem wrażliwości rozwiązań takich równań na odchyłki ich parametrów od nominalnych wartości. Zdefiniowano odpowiedni "różniczkowy" wskaźnik uwarunkowania oraz podano efektywną metodę szacowania jego wartości. Udowodniono teoretycznie - a także przekonująco zilustrowano na drodze numerycznej - twierdzenie głoszące, iż...
-
Robust pole placement in delta domain for SISO plans
Publication...
-
Lexicon Based Algorithm for Domain Ontology Merging and Alignment
PublicationMore and more systems contain some kind of knowledge describing their field of operation. Such knowledge in many cases is stored as an ontology. A need arises for ability to quickly match those ontologies to enable interoperability of such systems. The paper presents a lexicon based algorithm for merging and aligning of OWL ontologies. The proposed similarity levels are being presented and the proposed algorithm is being described....
-
Cross-domain applications of multimodal human-computer interfaces
PublicationDeveloped multimodal interfaces for education applications and for disabled people are presented, including interactive electronic whiteboard based on video image analysis, application for controlling computers with mouth gestures and audio interface for speech stretching for hearing impaired and stuttering people and intelligent pen allowing for diagnosing and ameliorating developmental dyslexia. The eye-gaze tracking system named...
-
Model-Based Testing of Embedded Systems in the Automotive Domain
PublicationPhD
-
On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
PublicationThe role of numerical optimization has been continuously growing in the design of high-frequency structures, including microwave and antenna components. At the same time, accurate evaluation of electrical characteristics necessitates full-wave electromagnetic (EM) analysis, which is CPU intensive, especially for complex systems. As rigorous optimization routines involve repetitive EM simulations, the associated cost may be significant....
-
Resonance Frequency Calculation of Spherical Microstrip Structure Using Hybrid Technique
PublicationIn this paper the spherical microstrip structure is considered. The structure is composed of a metallic patch with an arbitrary shape placed on a dielectric coated metallic sphere. In the analysis the hybrid technique is utilized. In this approach the finite-difference technique is applied in a cavity model to determine the current basis functions on the patch. Next, using method of moments, the resonance frequency of the structure...
-
Using Fast Frequency Hopping Technique to Improve Reliability of Underwater Communication System
PublicationAcoustic underwater communication systems designed to work reliably in shallow coastal waters must overcome major limitations such as multipath propagation and the Doppler effect. These restrictions are the reason for the complexity of receivers being built, whose task is to decode a symbol on the basis of the received signal. Additional complications are caused by the low propagation speed of the acoustic wave in the water and...
-
Physics-guided neural networks (PGNNs) to solve differential equations for spatial analysis
PublicationNumerous examples of physically unjustified neural networks, despite satisfactory performance, generate contradictions with logic and lead to many inaccuracies in the final applications. One of the methods to justify the typical black-box model already at the training stage and lead to many inaccuracies in the final applications. One of the methods to justify the typical black-box model already at the training stage involves extending...
-
Web-based real-time simulation system
PublicationThe paper presents the development of a simulation system composed of a real-time plant simulator with real-time controller included in the software-in-the-loop structure using web-based communication. The client-server architecture build in a TCP/IP network environment was introduced, where the server is a computing unit for real-time high temporal resolution plant simulation (and optionally also as controllers' platform) and...
-
Bounds on the Cover Time of Parallel Rotor Walks
PublicationThe rotor-router mechanism was introduced as a deterministic alternative to the random walk in undirected graphs. In this model, a set of k identical walkers is deployed in parallel, starting from a chosen subset of nodes, and moving around the graph in synchronous steps. During the process, each node maintains a cyclic ordering of its outgoing arcs, and successively propagates walkers which visit it along its outgoing arcs in...
-
Rapid Variable-Resolution Parameter Tuning of Antenna Structures Using Frequency-Based Regularization and Sparse Sensitivity Updates
PublicationGeometry parameter tuning is an inherent part of antenna design process. While most often performed in a local sense, it still entails considerable computational expenses when carried out at the level of full-wave electromagnetic (EM) simulation models. Moreover, the optimization outcome may be impaired if good initial design is not available. This paper proposes a novel approach to fast and improved-reliability gradient-based...
-
A Novel Trust-Region-Based Algorithm with Flexible Jacobian Updates for Expedited Optimization of High-Frequency Structures
PublicationSimulation-driven design closure is mandatory in the design of contemporary high-frequency components. It aims at improving the selected performance figures through adjustment of the structure’s geometry (and/or material) parameters. The computational cost of this process when employing numerical optimization is often prohibitively high, which is a strong motivation for the development of more efficient methods. This is especially...
-
Approach to evaluation of time to the critical degradation of ship pipelines
PublicationIn the article an approach to the problem of estimating time to the critical degradation of ship pipelines is considered. Such an assessment would consist of six stages. The fundamental idea is to include to the estimation of time to failure of pipelines such elements like: materials that the pipelines are made, destructive physical phenomena taking place in them and applied means of protection. The result of that evaluation should...
-
Real Time Operating Systems - Seminar 2021/22L
e-Learning Courses -
2022/2023 Global Digital Transformation-part time
e-Learning Courses -
2022/2023 Global Digital Transformation-Full time
e-Learning Courses -
Real time operating systems Seminars 2020-2021
e-Learning CoursesRTOS seminary classes.
-
Measurements of the fundamental harmonic frequency of voltages on main bars in a ship power station
Open Research DataThe presented dataset is part of research focusing on the assessment of metrological properties of the instrument, Estimator/Analyzer (E/A v.2), developed and made at the Faculty of Electrical Engineering, Department of Marine Electrical Power Engineering of Gdynia Maritime University. The attached dataset contains processed data, expressing the fundamental...
-
Bounds on the cover time of parallel rotor walks
PublicationThe rotor-router mechanism was introduced as a deterministic alternative to the random walk in undirected graphs. In this model, a set of k identical walkers is deployed in parallel, starting from a chosen subset of nodes, and moving around the graph in synchronous steps. During the process, each node successively propagates walkers visiting it along its outgoing arcs in round-robin fashion, according to a fixed ordering. We consider...
-
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...
-
Monitoring of the Process of System Information Broadcasting in Time
PublicationOne of the problems of quantum physics is how a measurement turns quantum, noncopyable data, towards copyable classical knowledge. We use the quantum state discrimination in a central system model to show how its evolution leads to the broadcasting of the information, and how orthogonalization and decoherence factors allow us to monitor the distance of the state in question to the one perfectly broadcasting information, in any...
-
Dew and hoarfrost frequency, formation efficiency and chemistry in Wroclaw, Poland
PublicationThis article presents the results of a research study concerning a comparison of frequency, formation efficiency and basic physico-chemical properties of dew and hoarfrost in urban conditions. Longer than two-year series of measurements was carried out from 1 February 2008 to 10 March 2010 in Wroclaw, Poland. Sampling of atmospheric deposits was made by means of insulated plain passive radiative condensers, which allowed to collect...
-
A new optimal algorithm for a time-dependent scheduling problem
PublicationIn this article a single machine time-dependent scheduling problem with total completion time criterion is considered. There are n given jobs j_1, ..., j_n and the processing time pi of the i-th job is given by p_i = 1 + b_is_i, where si is the starting time of the i-th job, i = 1, ..., n. If all jobs have different and non-zero deterioration rates and bi > bj => bi >= (b_min+1)/(b_min) b_j + 1/b_min, where b_min = min{b_i}, then...
-
Stability by linear approximation for time scale dynamical systems
PublicationWe study systems on time scales that are generalizations of classical differential or difference equations and appear in numerical methods. In this paper we consider linear systems and their small nonlinear perturbations. In terms of time scales and of eigenvalues of matrices we formulate conditions, sufficient for stability by linear approximation. For non-periodic time scales we use techniques of central upper Lyapunov exponents...
-
Investigation of noises in the EPN weekly time series
PublicationThe constantly growing needs of permanent stati ons’ velocities users cause their stability level to increase. To this research we included more than 150 stations located across Europe operating within the EUREF Permanent Network (EPN) w ith weekly changes in the ITRF2005 reference frame. The obvious long-range dependencies in the stochastic part of GPS time series were p roven by Ljung-Box...
-
Comparative Analysis of Developed Rainfall Intensity–Duration–Frequency Curves for Erbil with Other Iraqi Urban Areas
PublicationRainfall Intensity–Duration–Frequency (IDF) relationships are widely used in water infrastructure design and construction. IDF curves represent the relationship between rainfall intensity, duration, and frequency, and are obtained by analyzing observed data. These relationships are critical for the safe design of flood protection structures, storm sewers, culverts, bridges, etc. In this study, the IDF curves and empirical IDF formulas...
-
Improved method for real-time speech stretching
Publicationn algorithm for real-time speech stretching is presented. It was designed to modify input signal dependently on its content and on its relation with the historical input data. The proposed algorithm is a combination of speech signal analysis algorithms, i.e. voice, vowels/consonants, stuttering detection and SOLA (Synchronous-Overlap-and-Add) based speech stretching algorithm. This approach enables stretching input speech signal...
-
Pitch estimation of narrowband-filtered speech signal using instantaneous complex frequency
PublicationIn this paper we propose a novel method of pitch estimation, based on instantaneous complex frequency (ICF). New iterative algorithm for analysis of ICF of speech signal in presented. Obtained results are compared with commonly used methods to prove its accuracy and connection between ICF and pitch, particularly for narrowband-filtered speech signal.
-
Pitch estimation of narrowband-filtered speech signal using instantaneous complex frequency
PublicationIn this paper we propose a novel method of pitch estimation, based on instantaneous complex frequency (ICF). New iterative algorithm for analysis of ICF of speech signal in presented. Obtained results are compared with commonly used methods to prove its accuracy and connection between ICF and pitch, particularly for narrowband-filtered speech signal.
-
A spline-based FE approach to modelling of high frequency dynamics of 1-D structures
PublicationIn this paper a computational methodology leading to the development of a new class of FEs, based on the application of continuous and smooth approximation polynomials, being splines, has been presented. Application of the splines as appropriately defined piecewise elemental shape functions led the authors to the formulation of a new approach for FEM, named as spFEM, where contrary to the well-known NURBS approach, the boundaries...
-
DETERMINING THE TIME CONSTANT USING TWO METHODS AND DEFINING THE THERMOCOUPLE RESPONSE TO SINE EXCITATION OF GAS TEMPERATURE
PublicationThis paper describes the two methods of determining the time constant of type K thermocouple, for two construction solutions: the exposed weld and the mantle fillet weld. This is an important parameter indicating the response time of the thermocouple on the recorded signal. The first method consists of determining the value of τ in the way of numerical simulation of heat exchange between the thermocouple and the current of gas...