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Tytuł:
Reactive compensator synthesis in time-domain
Autorzy:
Siwczyński, M.
Jaraczewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/201083.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
power and energy theory
reactive power filters
reactive current
optimization
harmonic filter design
Opis:
The source reactive-current compensation is crucial in the energy transmission efficiency. The compensator design in a frequencydomain has already been widely discussed and examined. This paper presents results of a study on how to design reactive compensators in a time-domain. It is the first time the reactive compensator has been designed in a time domain. The example of a compensator is presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 1; 119-124
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-domain electromagnetic method in geological research
Autorzy:
Klityński, W.
Stefaniuk, M.
Miecznik, J.
Powiązania:
https://bibliotekanauki.pl/articles/191814.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Time-domain electromagnetic method
near zone
apparent resistivity
penetration depth
hydrocarbon prospecting
Opis:
This paper describes the theoretical basis of the time-domain electromagnetic method (TDEM) and its application in geological research. The paper discusses the behavior of the electromagnetic field of pulse current sources (magnetic dipole) in the near zone. The problem of the penetration depth of the TDEM method is discussed, in the context of its application in geological research and to gas exploration in the Rudka Gas Field, located in the Carpathian Foredeep. The TDEM sounding curves from the Rudka Field and the influence of noise on the penetration depth are discussed. A 1-D Occam inversion of TDEM soundings was obtained for a profile across the borehole A-10. An integrated (TDEM and borehole) interpretation of the data was made and a 2-D resistivity cross-section was obtained along the profile, as a contribution to geological reconnaissance for gas prospecting.
Źródło:
Annales Societatis Geologorum Poloniae; 2014, 84, 1; 71-79
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Time Domain Model of GPR Antenna Radiation Pattern
Autorzy:
Edemsky, F.
Popov, A.
Zapunidi, S.
Powiązania:
https://bibliotekanauki.pl/articles/226318.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
subsurface sensing
ground penetrating radar
electromagnetic pulse radiation
ground-air interface
time-domain Green function
spatio-temporal radiation pattern
inverse problem
deconvolution
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 407-411
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical time-domain model for tool point dynamics in turning
Autorzy:
Berglind, L.
Ziegert, J.
Powiązania:
https://bibliotekanauki.pl/articles/99687.pdf
Data publikacji:
2014
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
chatter
turning
analytical model
time domain
Opis:
An analytical time domain solution is developed to model the dynamic response of a tool during a simple turning operation. The time domain solution developed in this paper relies on the superposition principal under the linear assumption to construct the time response of single mode, single degree of freedom cutting tool. The results from the analytical solution are compared with those generated using numerical time domain simulations and it is found that the two solutions converge as the time step used in the numerical simulation decreases.
Źródło:
Journal of Machine Engineering; 2014, 14, 4; 75-94
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-consistent theory of random lasing in the time-domain
Autorzy:
Peterson, Z.
Powiązania:
https://bibliotekanauki.pl/articles/174763.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
random lasers
time-domain
condensed matter
optics
Opis:
Random lasers are unique systems where lasing occurs due to repetitive scattering in a disordered nanostructure. Previous descriptions of random lasing are numerous, however a full time-dependent theory that describes the introduction of gain directly from first principles is lacking in the literature. This paper will present an analytic self-consistent time-dependent theory of random lasing that contains the results from the well-known steady-state ab initio laser theory. This theory can also describe a number of temporal phenomena that have been observed in previous experiments and facilitates the incorporation of these devices into their envisioned practical applications.
Źródło:
Optica Applicata; 2018, 48, 4; 647-659
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric determination of moisture of wood using time domain reflectometry
Autorzy:
Malicki, M A
Kotlinski, J.
Powiązania:
https://bibliotekanauki.pl/articles/26096.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
moisture
determination
wood industry
wood
time domain reflectometry
drying process
Źródło:
International Agrophysics; 1998, 12, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-Domain Synthesis of Linear Circuits With Periodically Variable Parameters
Autorzy:
Siwczyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/911223.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
układ parametryczny
synteza
optymalizacja
parametric circuits
synthesis
optimisation
Opis:
A novel synthesis method of linear electric networks with periodically variable parameters is presented. These types of networks can be implemented as resistance-parametric, (conductance-capacitance)-parametric or (resistance- inductance)- parametric multiports. The time-varying parameters are determined so as to extremize some specific optimisation criteria. Consequently, the synthesis task has a unique solution. The starting point of the solution method is the original theorem proved in the paper, which deals with the minimum-energy networks.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2000, 10, 3; 623-637
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Starch Hydration by 2D Time Domain NMR
Autorzy:
Witek, M.
Peemoeller, H.
Szymońska, J.
Blicharska, B.
Powiązania:
https://bibliotekanauki.pl/articles/2044693.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.56.Na
82.35.Pq
Opis:
Proton exchange between spin groups of the solid matrix of hydrated granular potato starch and water was studied using the 2D time domain NMR. The proton spin-spin relaxation time T$\text{}_{2}$, and spin-lattice relaxation time T$\text{}_{1}$ (selective and non-selective pulse sequences) were measured at room temperature. The observed spin relaxation results were analysed for exchange assuming a two-site exchange model (between water and solid matrix of starch). In this analysis we determined the intrinsic spin-lattice relaxation time for water protons (49 ms) and solid starch matrix protons (172 ms), as well as the water-starch magnetization exchange rate (86 s$\text{}^{-1}$).
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 359-364
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
THz Reflection Spectroscopy of Explosives Measured by Time Domain Spectroscopy
Autorzy:
Palka, N.
Powiązania:
https://bibliotekanauki.pl/articles/1493255.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.57.Ty
07.57.Pt
78.20.Ci
78.40.Pg
Opis:
Reflection spectra of pure explosive materials and their simulants were measured in transmission and reflection by means of time domain spectroscopy in the range 0.1-3 THz. Spectra measured in two reflection configurations: specular with incident angle equal to 45° and stand-off with close to normal incidence and distance 30 and 40 cm to samples was analyzed.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 713-715
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz dielectric characterisation of fibres in a time-domain spectrometer
Autorzy:
Pacewicz, Adam
Kopyt, Paweł
Cuper, Jerzy
Krysicki, Mateusz
Salski, Bartłomiej
Powiązania:
https://bibliotekanauki.pl/articles/2204194.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
terahertz spectroscopy
fibre characterisation
dielectric materials
Opis:
An innovative measurement setup for the dielectric characterisation of fibres in a terahertz time-domain spectrometer using an HDPE elliptical lens for coupling into the fibres has been built and validated by measurements of several different types of samples. The setup is based on a commercial all fibre-coupled terahertz time-domain spectrometer. Measurements of the effective refractive index have been conducted on polypropylene-based three-dimensional printing filaments, silica glass rods, and a polytetrafluoroethylene cord of lowered density, covering the frequency range of approximately 100 GHz to 1 THz. The theoretical part of the work includes numerical calculations performed via the finite difference eigenmode method and the characteristic equations of a uniform circular dielectric waveguide for a few guided modes, from which it is clear that primarily the fundamental mode propagates along the fibre. Details on model-based phase corrections, crucial to the accurate determination of the effective refractive index of dispersive fibres, have been presented as well.
Źródło:
Opto-Electronics Review; 2023, 31, 2; art. no. e144596
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decentralized Variable Structure Tracking for Systems With Time-Domain Dominance
Autorzy:
Balluchi, A.
Bicchi, A.
Powiązania:
https://bibliotekanauki.pl/articles/908303.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
warunek dominujący
sterowanie
sterowanie rozproszone
dominance conditions
decentralized control
robust control
variables structure control (VSC)
Opis:
In this paper, we consider the design of tracking controllers for linear MIMO systems described by an input-output model. The presence of known 'weak' interactions among SISO or MIMO subsystems may allow the designer to achieve objectives by using independent controllers of lower complexity than are necessary in general (control decentralization problem). Sufficient conditions for asymptotic tracking employing decentralized variable structure techniques are derived. The condition is shown to be closely related to (and in a sense, a time-domain counterpart of) dominance criteria used in frequency-domain techniques, as they have developed out of Rosenbrock's original diagonal dominance concept. The synthesis of a decentralized variable-structure controller for asymptotic tracking is illustrated for systems obeying some conditions on their nominal relative degrees.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 2; 265-291
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The North Sea Bicycle Race ECG project : time-domain analysis
Autorzy:
Długosz, D.
Eftestøl, T.
Królak, A.
Wiktorski, T.
Ørn, S.
Powiązania:
https://bibliotekanauki.pl/articles/384850.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
ECG
principal Component Analysis
silhouette analysis
clustering
EKG
analiza głównych składowych
grupowanie
klastering
Opis:
Analysis of electrocardiogram and heart rate provides useful information about health condition of a patient. The North Sea Bicycle Race is an annual cycling competition in Norway. Examination of ECG recordings collected from participants of this race may allow defining and evaluating the relationship between physical endurance exercises and heart electrophysiology. Parameters reflecting potentially alarming deviations are to be identified in this study. This paper presents results of a time-domain analysis of ECG data collected in 2014, implementing K-Means clustering. A double stage analysis strategy, aimed at producing hierarchical clusters, is proposed. The first phase allows rough separation of data. Second stage is applied to reveal internal structure of the majority clusters. In both steps, discrepancies driving the separation could stem from three sources. Firstly, they could be signs of abnormalities in electrical activity of the heart. Secondly, they may allow discriminating between natural groups of participants – according to sex, age, physical fitness. Finally, some deviations could result from faults in data extraction, therefore serving in evaluation of the parameters. The clusters were defined predominantly by combinations of features: heartbeat signals correlation, P-wave shape, and RR intervals; none of the features alone was discriminative for all the clusters.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2018, 12, 1; 23-32
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
THz Time Domain Spectroscopy of Thin Gold Layers on GaAs
Autorzy:
Szczytko, J.
Adomavicius, R.
Papis, E.
Barańska, A.
Wawro, A.
Krotkus, A.
Piętka, B.
Łusakowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1417930.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Bz
78.68.+m
Opis:
Thin layers of Au with the thickness of several nanometers were prepared on a semi-insulating GaAs substrate. The layers' thickness was determined by ellipsometry. THz time-domain spectroscopy was applied to determine a complex index of refraction of thin Au layers. The obtained results allow for a more precise modeling of the performance of semiconductor devices at THz frequencies.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1118-1120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric determination of moisture of cereals grain using time domain reflectometry
Autorzy:
Malicki, M A
Kotlinski, J.
Powiązania:
https://bibliotekanauki.pl/articles/24294.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
moisture
determination
cereal grain
time domain reflectometry
Źródło:
International Agrophysics; 1998, 12, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time Domain Measurement Representation in Computer System Diagnostics and Performance Analysis
Autorzy:
Wideł, S.
Flak, J.
Gaj, P.
Powiązania:
https://bibliotekanauki.pl/articles/384100.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Time Domain Measurement Representation
Computer System Diagnostics
Opis:
Time analysis is a common approach for testing and detecting methods for the performance analysis of computer systems. In the article it is shown, that measuring and identifying performances based on a benchmark is not sufficient for the proper analysis of the computer systems behavior. The response time of the process is often composed of the execution of many subprocesses or many paths of execution. Under this assumption, it is presented, that both convolution and deconvolution methods can be helpful in obtaining time distributions and modeling of complex processes. In such a modeling the analysis of measurement errors is very important and was taken into consideration. The example of using the methods in buffering process is also discussed.
Źródło:
e-Informatica Software Engineering Journal; 2013, 7, 1; 53-64
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite-difference time-domain solution of second-order photoacoustic wave equation
Autorzy:
Rahimzadeh, A.
Chen, S.-L.
Powiązania:
https://bibliotekanauki.pl/articles/173969.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
photoacoustic tomography
numerical simulation
finite-difference time-domain
second-order photoacoustic equation
Opis:
A finite-difference time-domain numerical solution is presented for solving a single second-order photoacoustic equation, instead of solving three coupled first-order equations. In this way, we are able to insert the heating function to the simulation directly instead of initial pressure. Results are validated using k-Wave simulation and show a good agreement for future development. The perfectly matched layer boundary condition has been implemented for a second-order photoacoustic equation and results are compared to Dirichlet, Neumann and Mur boundary conditions.
Źródło:
Optica Applicata; 2016, 46, 3; 435-446
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-linear modelling of elastic hysteretic damping in the time domain
Autorzy:
Spitas, C.
Dwaikat, M. M. S.
Spitas, V.
Powiązania:
https://bibliotekanauki.pl/articles/38606055.pdf
Data publikacji:
2020
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
hysteresis
damping
modified viscous model
dynamics time-domain
mechanical vibration
frequency
non-linear modeling
Opis:
Elastic hysteretic damping is defined as the dissipation of energy at a rate that is weakly dependent on frequency of vibration. In this article, we propose that the elastic hysteretic damping can be achieved by a simple modification to the viscous damping model. The proposed modification is based on computing an instantaneous correction factor that recursively depends on the state variables of the system. This correction factor is related to the rate by which the velocity changes with respect to the displacement. The new model compares quite favourably with the other existing solutions in the time-domain and differences between the solutions become evident for higher damping ratios. It is found that the new model predicts consistently the weak variation in the loss factor as a function of frequency. In addition to its simple mathematical formulation, the proposed model is superior to the existing solutions in that it does not require knowledge of the past history of motion neither the knowledge of the excitation frequency and is extensible to any type of loading. Various aspects pertaining to the linearity of the proposed approach are finally discussed.
Źródło:
Archives of Mechanics; 2020, 72, 4; 323-353
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Digital Signal Processing Approach in Air Coupled Ultrasound Time Domain Beamforming
Autorzy:
Herman, K.
Gudra, T.
Furmankiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/177033.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beamforming
air-coupled ultrasounds
DSP
digital signal processing
bat signals
direction of arrival
Opis:
The work presents the results of experimental study on the possibilities of determining the source of an ultrasonic signal in two-dimensional space (distance, horizontal angle). During the research the team used a self-constructed linear array of MEMS microphones. Knowledge in the field of sonar systems was utilized to analyse and design a location system based on a microphone array. Using the above mentioned transducers and broadband ultrasound sources allows a quantitative comparison of estimation of the location of an ultrasonic wave source with the use of broadband modulated signals (modelled on bats’ echolocation signals) to be performed. During the laboratory research the team used various signal processing algorithms, which made it possible to select an optimal processing strategy, where the sending signal is known.
Źródło:
Archives of Acoustics; 2014, 39, 1; 37-50
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Time-domain Windowing on Isolated Speech Recognition System Performance
Autorzy:
Ananthakrishna, Thalengala
Anitha, H.
Girisha, T.
Powiązania:
https://bibliotekanauki.pl/articles/2055228.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hidden Markov model
HMM
isolated speech recognition system
ISR
Kannada language
mono-phone model
Mel frequency cepstral coefficients
MFCC
Opis:
Speech recognition system extract the textual data from the speech signal. The research in speech recognition domain is challenging due to the large variabilities involved with the speech signal. Variety of signal processing and machine learning techniques have been explored to achieve better recognition accuracy. Speech is highly non-stationary in nature and therefore analysis is carried out by considering short time-domain window or frame. In the speech recognition task, cepstral (Mel frequency cepstral coefficients (MFCC)) features are commonly used and are extracted for short time-frame. The effectiveness of features depend upon duration of the time-window chosen. The present study is aimed at investigation of optimal time-window duration for extraction of cepstral features in the context of speech recognition task. A speaker independent speech recognition system for the Kannada language has been considered for the analysis. In the current work, speech utterances of Kannada news corpus recorded from different speakers have been used to create speech database. The hidden Markov tool kit (HTK) has been used to implement the speech recognition system. The MFCC along with their first and second derivative coefficients are considered as feature vectors. Pronunciation dictionary required for the study has been built manually for mono-phone system. Experiments have been carried out and results have been analyzed for different time-window lengths. The overlapping Hamming window has been considered in this study. The best average word recognition accuracy of 61.58% has been obtained for a window length of 110 msec duration. This recognition accuracy is comparable with the similar work found in literature. The experiments have shown that best word recognition performance can be achieved by tuning the window length to its optimum value.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 1; 161--166
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of linear dispersive materials using scalable time domain finite element scheme
Autorzy:
Butryło, B.
Powiązania:
https://bibliotekanauki.pl/articles/140567.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dispersive dielectrics
electromagnetic field
finite element method
fractional relaxation
wideband numerical scheme
Opis:
This paper deals with some aspects of formulation and implementation of a broadband algorithm with build-in analysis of some dispersive media. The construction of the finite element method (FEM) based on direct integration of Maxwell’s equations and solution of some additional convolution integrals is presented. The broadband, fractional model of permittivity is approximated by a set of some relaxation sub-models. The properties of the 3D time-dependent formulation of the FEM algorithm are determined using a benchmark problem with the Cole-Cole and the Davidson-Cole models. Several issues associated with the implementation and some constraints of the broadband finite element algorithm are presented.
Źródło:
Archives of Electrical Engineering; 2016, 65, 4; 719-732
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A time-domain pulse amplitude and width discrimination method for photon counting
Autorzy:
del Mar Correa, M.
Pérez, F. R.
Powiązania:
https://bibliotekanauki.pl/articles/220971.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
field-programmable gate array
time-to-digital converter
spectroscopy
photomultiplier
photon counting
discriminator
after-pulsing
low-voltage differential signalling
Opis:
This work shows a time-domain method for the discrimination and digitization of parameters of voltage pulses coming from optical detectors, taking into account the presence of electronic noise and afterpulsing. Our scheme is based on an FPGA-based time-to-digital converter as well as an adjustable-threshold comparator complemented with commercial elements. Here, the design, implementation and optimization of a multiphase TDC using delay lines shorter than a single clock period is also described. The performance of this signal processing system is discussed through the results from the statistical code density test, statistical distributions of measurements and information gathered from an optical detector. Unlike dual voltage threshold discriminators or constant-fraction discriminators, the proposed method uses amplitude and time information to define an adjustable discrimination window that enables the acquisition of spectra.
Źródło:
Metrology and Measurement Systems; 2018, 25, 2; 269-282
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of ADC Resolution on Low-Frequency Electrical Time-Domain Impedance Spectroscopy
Autorzy:
Namin, R. L.
Ashtiani, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/221144.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electrical impedance spectroscopy
analogue-to-digital converter
Ramp signal
fast Fourier transform
Nyquist plot
Opis:
In this paper, the effect of the resolution of an analogue-to-digital converter (ADC) on the accuracy of timedomain low-frequency electrical impedance spectroscopy is examined. For the first time, we demonstrated that different wideband stimuli signals used for impedance spectroscopy have different sensitivities to the resolution of ADC used in impedance spectroscopy systems. We also proposed Ramp and Half-Gaussian signals as new wideband stimulating signals for EIS. The effect of ADC resolution was studied for Sinc, Gaussian, Half-Gaussian, and Ramp excitation signals using both simulation and experiments. We found that Ramp and Half-Gaussian signals have the best performance, especially at low frequencies. Based on the results, a wideband electrical impedance spectroscopy circuit was implemented with a high accuracy at frequencies bellow 10 Hz.
Źródło:
Metrology and Measurement Systems; 2017, 24, 2; 425-436
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time domain reflectometry as a tool for the estimation of quality in foods
Autorzy:
Kent, M.
Knochel, R.
Daschner, F.
Schimmer, O.
Oehlenschlager, J.
Mierke-Klemeyer, S.
Barr, U.K.
Floberg, P.
Tejada, M.
Huidobro, A.
Nunes, L.
Batista, I.
Martins, A.
Powiązania:
https://bibliotekanauki.pl/articles/24653.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
fish product
fish
microwave
food
fish fillet
time domain reflectometry
quality
storage condition
Źródło:
International Agrophysics; 2004, 18, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intraoperative imaging based on common-path time-domain reflectometry for brain tumor surgery
Autorzy:
Han, Jae-Ho
Cha, Jaepyeong
Powiązania:
https://bibliotekanauki.pl/articles/174648.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical coherence tomography
intraoperative imaging
reflectometry
endoscopy
Opis:
Minimally invasive intraoperative imaging plays a crucial role in delicate microsurgeries for precise operation monitoring in which fiber optic imaging can be considered as an endoscopy and surgical proximity guidance tool due to its compactness. This paper presents a near-infrared time-domain reflectometric common-path optical coherence tomography imaging technique using a bare-fiber probe mounted directly on a scanning galvanometer. The common-path setup allows the use of a freely adjustable optical path length and a disposable fiber probe, as well as eliminating the need for an additional dedicated reference optical path. Experimental results demonstrate clear discrimination between the brain tumor tissue and the normal tissue for mouse brains with the images acquired in real-time over a wide area. The proposed method enables real-time and in situ visualization of tumor resection for intraoperative imaging, and this study demonstrates the feasibility of its application to microsurgical interventions.
Źródło:
Optica Applicata; 2020, 50, 2; 223-227
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite-Difference Time-Domain Simulation of Mid- and Far-Infrared Quantum Cascade Lasers
Autorzy:
Tamošiūnas, V.
Kancleris, Ž.
Dagys, M.
Simniškis, R.
Tamošsiūnienė, M.
Valušis, G.
Strasser, G.
Unterrainer, K.
Powiązania:
https://bibliotekanauki.pl/articles/2041682.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.30.+q
78.66.-w
85.30.De
Opis:
We present simulations of mid- and far-infrared quantum cascade lasers operating with/without external magnetic field. Maxwell-Bloch solver based on the finite-difference time-domain method was used in our investigation. Reduction of the far-infrared quantum cascade laser emission intensity is associated with increased optical losses in highly doped layers when magnetic field is changed from 4.2 T to 6.2 T. A simulated emission spectrum of mid-infrared disc-shaped quantum cascade laser with 60μm radius is consistent with the experimentally observed irregular spacing between quantum cascade laser emission lines.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 179-183
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Algorithm for determining two-periodic steady-states in AC machines directly in time domain
Autorzy:
Sobczyk, T.J.
Powiązania:
https://bibliotekanauki.pl/articles/141171.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
AC machines
steady state analysis
two-periodic solutions
analysis in time domain
discrete differential operator
iterative algorithms
Opis:
This paper describes an algorithm for finding steady states in AC machines for the cases of their two-periodic nature. The algorithm enables to specify the steady-state solution identified directly in time domain despite of the fact that two-periodic waveforms are not repeated in any finite time interval. The basis for such an algorithm is a discrete differential operator that specifies the temporary values of the derivative of the twoperiodic function in the selected set of points on the basis of the values of that function in the same set of points. It allows to develop algebraic equations defining the steady state solution reached in a chosen point set for the nonlinear differential equations describing the AC machines when electrical and mechanical equations should be solved together. That set of those values allows determining the steady state solution at any time instant up to infinity. The algorithm described in this paper is competitive with respect to the one known in literature an approach based on the harmonic balance method operated in frequency domain.
Źródło:
Archives of Electrical Engineering; 2016, 65, 3; 575-583
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The CFD method-based research on damaged ship’s flooding process in time-domain
Autorzy:
Hu, Li-Fen
Qi, Huibo
Li, Yuemeng
Li, Wubin
Chen, Shude
Powiązania:
https://bibliotekanauki.pl/articles/259812.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
flooding process
Bernoulli equation
time domain calculation
damaged ship
Opis:
The flooding process is one of the main concerns of damaged ship stability. This paper combines the volume of fluid (VOF) method incorporated in the Navier-Stokes (NS) solver with dynamic mesh techniques to simulate the flooding of a damaged ship. The VOF method is used to capture the fluid interface, while the dynamic mesh techniques are applied to update the mesh as a result of transient ship motions. The time-domain flooding processes of a damaged barge and a rectangular cabin model are carried out based on the abovementioned method, and the computational results appear compatible with the experimental data. During the flooding process, the motion of the flooding flow at different stages is observed and compared with that observed in real conditions. The time-domain research of the flooding process is the starting point for subsequent establishment of damaged ship’s roll movement and capsizing the mechanism of dead ship condition in wave.
Źródło:
Polish Maritime Research; 2019, 1; 72-81
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of aggregate size on the water content estimated with time domain reflectance [TDR]
Autorzy:
Whalley, W.R.
Leeds-Harrison, P.B.
Whitmore, A.P.
Sarker, P.K.
Powiązania:
https://bibliotekanauki.pl/articles/25515.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
soil structure
time domain reflectance
calibration
aggregate size
water content
Źródło:
International Agrophysics; 2004, 18, 2
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computing Impulse Response of Room Acoustics Using the Ray-Tracing Method in Time Domain
Autorzy:
Alpkocak, A.
Sis, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/177974.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
acoustics simulation
Opis:
This paper proposes a new approach for calculating the impulse response of room acoustics. Impulse response provides unique characterization of any discrete lineartime invariant (LTI) systems. We assume that the room is a linear time-invariant system and the impulse response is calculated simply by sending a Dirac Impulse into the system as input and getting the response from the output. Then, the output of the system is represented as a sum of time-shifted weighted impulse responses. Both mathematical justifications for the proposed method and results from simulation software developed to evaluate the proposed approach are presented in detail.
Źródło:
Archives of Acoustics; 2010, 35, 4; 505-519
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency and time domain characteristics of digital control of electric vehicle in-wheel drives
Autorzy:
Jarzebowicz, L.
Opalinski, A.
Powiązania:
https://bibliotekanauki.pl/articles/141142.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
variable speed drives
modeling
digital control events
anti-lock braking
inwheel drives
Opis:
In-wheel electric drives are promising as actuators in active safety systems of electric and hybrid vehicles. This new function requires dedicated control algorithms, making it essential to deliver models that reflect better the wheel-torque control dynamics of electric drives. The timing of digital control events, whose importance is stressed in current research, still lacks an analytical description allowing for modeling its influence on control system dynamics. In this paper, authors investigate and compare approaches to the analog and discrete analytical modeling of torque control loop in digitally controlled electric drive. Five different analytical models of stator current torque component control are compared to judge their accuracy in representing drive control dynamics related to the timing of digital control events. The Bode characteristics and stepresponse characteristics of the analytical models are then compared with those of a reference model for three commonly used cases of motor discrete control schemes. Finally, the applicability of the presented models is discussed.
Źródło:
Archives of Electrical Engineering; 2017, 66, 4; 829-842
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weighted averaging of ECG signals based on partition of input set in time domain
Autorzy:
Momot, A.
Momot, M.
Łęski, J.
Powiązania:
https://bibliotekanauki.pl/articles/333836.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Tematy:
sygnał EKG
ważone uśrednianie
redukcja hałasu
ECG signal
weighted averaging
noise reduction
Opis:
The paper presents new approach to problem of signal averaging which is commonly used to extract a useful signal distorted by a noise. The averaging is especially useful for biomedical signal such as ECG signal, where the spectra of the signal and noise significantly overlap. In reality can be observed variability of noise power from cycle to cycle which is motivation for using methods of weighted averaging. Performance of the new method, based on partition of input set in time domain and criterion function minimization, is experimentally compared with the traditional averaging by using arithmetic mean, weighted averaging method based on empirical Bayesian approach and weighted averaging method based on criterion function minimization.
Źródło:
Journal of Medical Informatics & Technologies; 2007, 11; 165-170
1642-6037
Pojawia się w:
Journal of Medical Informatics & Technologies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time Domain Reflectometry (TDR) - Measuring Dielectric Constant of Polluted Soil to Estimate Diesel Oil Content
Autorzy:
Olchawa, A.
Kumor, M.
Powiązania:
https://bibliotekanauki.pl/articles/241025.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
contaminated soils
dielectric permittivity
TDR
oil diesel content
Opis:
The paper presents results of experimental study on the possibility of calculating the content of diesel oil in soils from measurements of dielectric permittivity with the TDR technique in a soil-water-air-diesel oil system. Results of calculation were compared with the actual content of diesel oil measured in laboratory conditions. The comparison shows that the content of diesel oil in soils may be precisely determined pn the basid of measurements of dielectric permittivity in contaminated soils.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2008, 55, 1-2; 55-62
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Transients in a Three-Level DC–DC Flying Capacitor Converter. Time Domain Approach
Autorzy:
Reznikov, Boris
Ruderman, Alexander
Galanina, Valentina
Powiązania:
https://bibliotekanauki.pl/articles/1193695.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
three-level DC–DC converter
flying capacitor
transient
natural balancing
Opis:
The paper considers a discrete state-space model for transients in a three-level flying capacitor DC–DC converter. A transition matrix is obtained for a pulse width modulation (PWM) period. The matrix elements are expanded into a power series using a selected small parameter. The matrix eigenvalues that determine the natural balancing dynamics transients are presented in the form of power series as well. Four separate transients are constructed based on four possible PWM period initial states (topologies). Inductor current and capacitor voltage transients are found for the voltage source power-up as the arithmetic average of the four separate transients. The discrete solutions are replaced by continuous ones. The resulting transients that are elementary functions of the circuit parameters, PWM period, and voltage reference demonstrate good agreement with the simulation results.
Źródło:
Power Electronics and Drives; 2019, 4, 39; 33-45
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Joint Timing Synchronization and Channel Estimation Using Perfect Sequence in Uplink Time Domain Synchronous OFDMA
Autorzy:
Lakshmanan, M.
Mallick, P.S.
Nithyanandan, L.
Powiązania:
https://bibliotekanauki.pl/articles/226994.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
timing synchronization
channel estimation
TDS-OFDMA
perfect sequence
guard interval
Opis:
Time Domain Synchronous Orthogonal Frequency Division Multiple Access (TDS-OFDMA) is used in mobile broadband wireless access scheme in uplink transmission. This leads to multiple user interference due to timing offset and frequency offset. In this paper, the effect of timing offset and channel estimation in mobile broadband system is analysed. Time-space two dimensional structure is used in TDS-OFDMA and perfect sequence is used for guard interval to achieve perfect timing synchronization and channel estimation for each user. Simulations are performed for timing synchronization and channel estimation using perfect sequence under Urban channel, Indoor Office B channel and HIPER LAN-A channel. Simulation results show that the timing synchronization is achieved and channel estimation performance using perfect sequence is better than CAZAC and PN Sequences.
Źródło:
International Journal of Electronics and Telecommunications; 2016, 62, 3; 225-229
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Spectra of Explosives Measured by Optical Parametric Oscillator-Based System and Time Domain Spectroscopy
Autorzy:
Palka, N.
Trzcinski, T.
Szustakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1418089.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.57.Ty
78.20.Ci
78.40.Pg
42.65.Yj
07.57.Kp
Opis:
In this paper, we report on measurements of absorption spectra of hexogen, penthrite, and octogen. The measurements were carried out by means of time domain spectroscopy and compared to spectra obtained from a setup, which bases on an optical parametric oscillator combined with a Golay cell. For time domain spectroscopy measurement, Teraview TPS 3000 unit with accessories in transmission configuration was used.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 946-949
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extrapolation of Electromagnetic Response from Linear Antennas in Time Domain without Late-Time Instabilities in Numerical Solution of EFI Equation
Autorzy:
Witenberg, Anna
Powiązania:
https://bibliotekanauki.pl/articles/308882.pdf
Data publikacji:
2020
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
electric field integral equation (EFIE)
linear antenna
solution of time domain EFIE
late time instabilities
Opis:
The paper presents a new hybrid method relied upon to solve integral equations of the electric field in time domain and to model linear antennas with pulse excitation. The method consists in a mixed, numerical-analytical description of the process that helps maintain the stability of calculations during the late time phase. As described in the analytical part, the modified spherical Bessel function of the first kind allows for extrapolation with a high degree of accuracy and loworder expressions. The modified spherical Bessel functions of the first kind are of the oscillating character, and their combination with the exponential factor makes them convenient for extrapolation of the answer of the antenna with pulse excitation. New functions are introduced to computational practice.
Źródło:
Journal of Telecommunications and Information Technology; 2020, 2; 45-50
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methods of DC/DC converter transfer function measurements, based on data acquired in the time domain
Autorzy:
Walczak, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/220796.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
DC–DC converters
frequency characteristics
transfer function measurement
Opis:
The measurement of frequency characteristics, like magnitude and phase, related to a specific transfer function of DC–DC converters, can be a difficult task - especially when the measured signal approaches the boundary of a small-signal model validity (i.e. 1/3 of the switching frequency fS ). It is hard to find a paper where authors mention the measurement techniques they use to draw frequency characteristics. Meanwhile the presence of noise in the output signal does not enable to directly measure the gain and the phase shift between the input and output signals. In such situations additional analysis is required in order to achieve a reliable result. This paper contains a description of a few methods that can be used to analyse measured signals in order to determine the gain and the phase shift of a specific transfer function. They enable to verify mathematical models in a wide range of frequencies (up to 1/3 fS ). The methods use signals measured in the time domain and can be implemented in mathematical software such as Matlab or Scilab.
Źródło:
Metrology and Measurement Systems; 2019, 26, 4; 661-671
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Electromagnetic Wave Absorber Based on Carbon Fiber Reinforced Aerated Concrete Using Time-Domain Method
Autorzy:
Laukaitis, A.
Sinica, M.
Balevičius, S.
Levitas, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813404.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
81.05.Uw
Opis:
The electromagnetic wave absorbers prepared from autoclaved aerated concrete containing carbon fibers as additions in the shape of slabs with pyramids cut on one plane of these slabs were tested using dc microwave source and the time-domain method. It was demonstrated that autoclaved aerated concrete allows one to fabricate electromagnetic wave absorbers which have a reflection coefficient up to -30 dB in the frequency range from 2 GHz to 18 GHz.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 1047-1050
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The time domain analysis of interactions in the wheel - rail contacts due to discontinuous time periodic loads
Autorzy:
Trzaska, M.
Trzaska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/246731.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
railway transport
wheel-rail contact
discontinuous time periodic forces
energy absorbed by rail
strength susceptibility
Opis:
In this paper, we present Fourier series less approaches for determining the energy produced by discontinuous time periodic forces in the wheel-rail contacts of the railway track systems. The vehicle system model used in this study consists of a quarter car supported on a bogie, while the side frame is supported on two wheel sets. The main advantage of the presented method is the total elimination of frequency analysis, which in effect introduces important simplifications in the identification of the energetic effects in the contact. Fundamental properties of contact displacements of the rail surface have been considered on the basis of the newly established method. The contact zone between railway wheels and the rail surfaces made of bulk materials is perceived as strong enough to resist the normal (vertical) forces introduced by heavy loads and the dynamic response induced by track and wheel irregularities. The analysis is carried out for a wheel running on an elastic rail rested on sleepers arranged on completely rigid foundation. The established model of the wheel-rail contact dynamics has been applied to that same roll plane, but with taking into account a nonlinear characteristic of the sleeper with respect to the ground. Attention then is focused completely on the modelling of the energy absorbed by the rail. The applied method employs the energy state variables as time functions leading to determine the susceptibility of a given contact on the strength induced by the rail roll.
Źródło:
Journal of KONES; 2012, 19, 2; 531-542
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-domain decomposition for optimal control problems governed by semilinear hyperbolic systems with mixed two-point boundary conditions
Autorzy:
Krug, Richard
Leugering, Günter
Martin, Alexander
Schmidt, Martin
Weninger, Dieter
Powiązania:
https://bibliotekanauki.pl/articles/2183473.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
time-domain decomposition
optimal control
semilinear hyperbolic systems
convergence
Opis:
In this article, we study the time-domain decomposition of optimal control problems for systems of semilinear hyperbolic equations and provide an in-depth well-posedness analysis. This is a continuation of our work, Krug et al. (2021) in that we now consider mixed two-point boundary value problems. The more general boundary conditions significantly enlarge the scope of applications, e.g., to hyperbolic problems on metric graphs with cycles. We design an iterative method based on the optimality systems that can be interpreted as a decomposition method for the original optimal control problem into virtual control problems on smaller time domains.
Źródło:
Control and Cybernetics; 2021, 50, 4; 427--455
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An automatic time domain reflectometry device to measure and store soil moisture contents for stand-alone field use
Autorzy:
Van Den Elsen, H.G.M.
Kokot, J.
Skierucha, W.
Halbertsma, J.M.
Powiązania:
https://bibliotekanauki.pl/articles/25409.pdf
Data publikacji:
1995
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
reflectometry
soil
moisture measurement
moisture content
time domain reflectometry technique
water content
Źródło:
International Agrophysics; 1995, 09, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In-situ measurements of moisture using surface TDR probes
Pomiary wilgotności in-situ przy zastosowaniu powierzchniowych sond TDR
Autorzy:
Suchorab, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1819344.pdf
Data publikacji:
2012
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
time domain reflectometry
soil water content
Opis:
Problem of building barriers moisture is a well known phenomenon for almost all users of the buildings. Its presence is inevitable in moderate climate and its balanced states are acceptable. On the other hand, extended values of moisture are disadvantageous and may be caused by many factors like water vapor condensation inside the barriers, capillary rise of ground water, rainwater, inundations or sanitary systems failures. This phenomenon is also a factor which limits the object functionality both from the construction and sanitary-hygienic reasons. Extended moisture content problem is particularly visible in the historical buildings which were set up without the suitable horizontal water-proof isolations. In this cases, ground water has the unlimited access to the groundwork and then, due to the capillary forces to the internal parts of the walls. Increased amounts of water lead to the material structure destruction by melting and thawing processes during winter season, wood decay, and accelerated corrosion of steel reinforcement elements and crystallization of dissolved salts in transported water. Also it should be mentioned here, that indirectly, water negatively influences the indoor environment providing good conditions for harmful microorganisms and mould development which may consequently run to the respiratory system diseases, infections, allergies, eyes and skin irritations. All above presented negative consequences of water presence inside the building envelopes are the reason for constant development moisture detection techniques.
Zjawisko zawilgocenia przegród budowlanych jest znane w zasadzie wszystkim użytkownikom obiektów budowlanych. Występowanie tego zjawiska jest praktycznie nie uniknione w warunkach klimatycznych w jakich znajduje się Polska. Jego zrównoważona obecność polegająca na ciągłym pochłanianiu wilgoci i jej odparowywaniu jest jak całkowicie akceptowalna. Szkodliwym jest natomiast zjawisko nadmiernej zawartości wilgoci, które może być wywołane wieloma czynnikami do których zaliczamy kondensację pary wodnej wewnątrz przegrody, podciąganie kapilarne wód gruntowych, wody rozbryzgowe z deszczy, wody powodziowe czy też awarie instalacji sanitarnych. Zjawisko powyższe jest niekorzystne z punktu widzenia budowli i jest czynnikiem ograniczającym funkcjonalność obiektu zarówno ze względów konstrukcyjnych, jak i higieniczno-sanitarnych. Problem nadmiernej zawartości wody w murach jest szczególnie widoczny w budynkach historycznych wznoszonych bez zastosowania właściwych izolacji poziomych. Wówczas woda gruntowa posiada nieograniczony dostęp do fundamentów budynku, a następnie przy udziale sił kapilarnych do wnętrza murów. Nadmierna ilość wody w zewnętrznych przegrodach budowlanych prowadzi do zniszczenia struktury materiału poprzez wielokrotne procesy zamarzania i rozmarzania w okresie zimowym, rozkład drewna, przyspieszoną korozja stalowych elementów zbrojeniowych oraz krystalizacja soli rozpuszczonych w transportowanej wodzie. Istotnym problemem jest również fakt, że woda pośrednio negatywnie oddziałuje na środowisko wewnętrzne pomieszczeń, przyczyniając się tym samym do rozwoju szkodliwych mikroorganizmów oraz grzybów pleśniowych. Może w konsekwencji przyczyniać się do chorób dróg oddechowych, infekcji, alergii oraz podrażnień oczu i skóry. Przedstawione powyżej negatywne skutki obecności wody w przegrodach budowlanych są podstawą do rozwoju i ciągłego opracowywania i udoskonalania technik detekcji wilgoci w przegrodach budowlanych. W niniejszym artykule przedstawiono możliwość przeprowadzenia badań in-situ przy zastosowaniu techniki pomiarowej TDR (Time Domain Reflectometry). Technika ta od wielu lat stosowana była do pomiarów wilgotności ośrodków gruntowych. Od początku XXI wieku trwały prace nad zastosowaniem techniki TDR do oceny zawilgocenia twardszych od gruntu materiałów i przegród budowlanych. Jednak inwazyjny charakter metody w większości przypadków uniemożliwiał jej praktyczne wykorzystanie lub był przyczyną wielu problemów technicznych. W ramach części badawczej artykułu przedstawiono pomiary wilgotności muru z cegły ceramicznej pełnej pokrytej warstwą tynku wapiennopiaskowego. Badany obiekt znajduje się na Lubelskiej starówce i jest to ściana bramy przy ul. Ku Farze. Jest to przegroda dotknięta zjawiskiem podciągania kapilarnego wynikającego z braku właściwych izolacji poziomych. Badania przeprowadzono w trzech terminach pomiarowych przy pomocy opracowanych na Politechnice Lubelskiej sond powierzchniowych TDR, umożliwiających bezinwazyjne pomiary wilgotności. W celu wykonania pomiarów, badaną przegrodę podzielono na charakterystyczne fragmenty tworzące siatkę pomiarową o określonych wymiarach. W trakcie eksperymentu w charakterystycznych punktach przegrody umieszczano czujnik i odczytywano parametry dielektryczne ośrodka, automatycznie przeliczając je na wilgotność objętościową. Wyniki przeprowadzonych badań naniesiono na siatkę pomiarów różnicując je kolorami w zależności od odczytanej wilgotności. Rezultatem powyższych zabiegów było uzyskanie tzw. map wilgotności przegrody budowlanej w trzech różnych terminach pomiarowych. Przedstawione w artykule mapy wilgotności potwierdzają fakt podwyższonej wilgotności przegrody i jednocześnie pozwalają na ukazanie jego rozkładu w pionie oraz poziomie. Przeprowadzone badania wyraźnie ukazują, że badana przegroda wykazuje nadmierną wilgotność w swych dolnych partiach, natomiast wyższe partie są nieco mniej wilgotne. Świadczy to o tym, że przyczyną nadmiernego zawilgocenia są wody gruntowe podciągane kapilarnie do wewnątrz struktury materiału. Wyniki badań przedstawione w artykule dowodzą skuteczności rozwijanych powierzchniowych sond TDR do bezinwazyjnego pomiaru wilgotności materiałów i przegród budowlanych oraz wskazują na przyczyny tego zjawiska w obiektach rzeczywistych.
Źródło:
Rocznik Ochrona Środowiska; 2012, Tom 14; 107-122
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of ship motions via a three-dimensional time-domain method following a quad-tree adaptive mesh technique
Autorzy:
Zhang, Teng
Ren, Junsheng
Liu, Lu
Powiązania:
https://bibliotekanauki.pl/articles/259860.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Froude-Krylov forces
adaptive mesh technique
analytical
transient free surface Green function
precise integration method
Opis:
A three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude- Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.
Źródło:
Polish Maritime Research; 2020, 1; 29-38
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the electromagnetic response of complex dispersive material with the single-step wideband finite element method
Autorzy:
Butryło, B.
Powiązania:
https://bibliotekanauki.pl/articles/141234.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
propagation of electromagnetic pulse
dielectric dispersion
frequency selective materials
broadband time-domain simulation
finite element time-domain method
Opis:
The paper describes the formulation and implementation of the broadband finite element time domain algorithm. The presented formalism is valid to analysis of electromagnetic phenomena in linear, frequency selective materials. The complex profile of permittivity of materials is approximated using a set of the Lorentz resonance models. The solution of the integro-differential second order equation is obtained using a singlestep integration scheme and a recursive convolution algorithm. The discussed formulation enables to adopt the structure of the narrowband part as well as the phase of calculation of the convolution equations for the subsequent components. The properties of the algorithm are validated using a finite difference broadband algorithm.
Źródło:
Archives of Electrical Engineering; 2013, 62, 1; 111-122
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolonged job strain reduces time-domain heart rate variability on both working and resting days among cardiovascular-susceptible nurses
Autorzy:
Borchini, Rossana
Bertù, Lorenza
Ferrario, Marco M.
Veronesi, Giovanni
Bonzini, Matteo
Dorso, Marco
Cesana, Giancarlo
Powiązania:
https://bibliotekanauki.pl/articles/2176995.pdf
Data publikacji:
2015-02-24
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
nurses
job strain
heart rate variability
HRV
time-domain parameters
ECG-monitoring
Opis:
Introduction Modifications of hearth rate variability (HRV) constitute a marker of the autonomic nervous system (ANS) deregulation, a promising pathway linking job strain (JS) and cardiovascular diseases (CVD). The study objective is to assess whether exposures to recent and prolonged JS reduce time-domain HRV parameters on working days (WD) among CVD-susceptible nurses and whether the association also persists on resting days (RD). Material and methods 313 healthy nurses were investigated twice with one year interval to assess JS based on the demand-control and the effort-reward models. 36, 9 and 16 CVD-susceptible nurses were classified as low JS in both surveys (stable low strain – SLS), recent high JS (high JS at the second screening only-RHS) and prolonged high JS (high strain in both surveys-PHS), respectively. In 9, 7 and 10 of them, free from comorbidities/treatments interfering with HRV, two 24-h ECG recordings were performed on WD and RD. Differences in the time domain HRV metrics among JS categories were assessed using ANCOVA, adjusted for age and smoking. Results In the entire sample (mean age: 39 years, 83% females) the prevalence of high job strain was 38.7% in the second survey. SDNN (standard deviation of all normal RR intervals) on WD significantly declined among JS categories (p = 0.02), with geometric mean values of 169.1, 145.3 and 128.9 ms in SLS, RHS, PHS, respectively. In the PHS group, SDNN remained lower on RD as compared to the low strain subjects (142.4 vs. 171.1 ms, p = 0.02). Similar findings were found for the SDNN_Index, while SDANN (standard deviation of average RR intervals in all 5 min segments of registration) mean values reduced in the PHS group during WD only. Conclusions Our findings suggest that persistent JS lowers HRV time-domain parameters, supporting the hypothesis that the ANS disorders may play an intermediate role in the relationship between work stress and CVD.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2015, 28, 1; 42-51
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Implementation of a Compact Smart Resistive Sensor Based on a Microcontroller with an Internal ADC
Autorzy:
Czaja, Z.
Powiązania:
https://bibliotekanauki.pl/articles/221453.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
microcontrollers
resistance measurement
ADC
time-domain measurements
Opis:
In the paper a new implementation of a compact smart resistive sensor based on a microcontroller with internal ADCs is proposed and analysed. The solution is based only on a (already existing in the system) microcontroller and a simple sensor interface circuit working as a voltage divider consisting of a reference resistor and a resistive sensor connected in parallel with an interference suppression capacitor. The measurement method is based on stimulation of the sensor interface circuit by a single square voltage pulse and on sampling the resulting voltage on the resistive sensor. The proposed solution is illustrated by a complete application of the compact smart resistive sensor used for temperature measurements, based on an 8-bit ATxmega32A4 microcontroller with a 12-bit ADC and a Pt100 resistive sensor. The results of experimental research confirm that the compact smart resistive sensor has 1°C resolution of temperature measurement for the whole range of changes of measured temperatures.
Źródło:
Metrology and Measurement Systems; 2016, 23, 2; 225-238
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
TDR technique for estimating the intensity of effective non rainfall
Autorzy:
Janik, G
Skierucha, W.
Blas, M.
Sobik, M.
Albert, M.
Dubicki, M.
Zawada, A.
Powiązania:
https://bibliotekanauki.pl/articles/26139.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
time domain reflectometry technique
time-domain reflectometer zob.TDR technique
intensity
non-rainfall water flux
water infiltration
soil
Opis:
The objective of this paper is to present a method for determining diurnal distribution of the intensity of effective non rainfall water flux. It was found that the application of TDR technique for the determination of diurnal dynamics of effective non rainfall water flux requires temperature correction of sensed volumetric moisture contents. Without temperature correction the error of estimated non rainfall water flux can be as much as 26%. In addition, the effect of temperature changes on the soil surface was determined in 0.5, 1, 2, 3, 4, and 5 hours periods. It was found that the intensity of effective non rainfall water flux was determined to the greatest extent by the rate of temperature drop during the period of 3 h preceding the non rainfall water flux determination. The agreement of non rainfall water flux calculated with the method proposed and that obtained by the collector was better for dew than for hoarfrost periods.
Źródło:
International Agrophysics; 2014, 28, 1
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of selected algorithms for force identification in time domain
Porównanie wybranych algorytmów identyfikacji wymuszeń działających w dziedzinie czasu
Autorzy:
Deręgowski, J.
Mendrok, K.
Powiązania:
https://bibliotekanauki.pl/articles/329588.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
identyfikacja wymuszeń
zagadnienie odwrotne
force identification
inverse problems
Opis:
In recent years one can observe significant growth of the interest in the structural health monitoring (SHM) systems development and applications. However many authors focuses on the damage detection and all the activities related with diagnosis of failure. Meanwhile, classical, full SHM system should have in addition to a diagnostic module also module for excitation monitoring. Excitation can be measured, but easier and cheaper is to identify it by measuring the response of the object. Often it is the only practical possibility to monitor the excitation. The authors took this often overlooked problem of SHM systems, comparing the most commonly used algorithms for the identification of excitation acting in the time domain in terms of their usefulness in SHM systems. Showing a description of each of the algorithms and simulation results. The following features were compared: accuracy of the excitation reconstruction, simplicity of the algorithm, including the amount and type of data needed to build the model.
W ostatnich latach obserwuje się znaczny wzrost zainteresowania budową i zastosowaniami układów monitorowania stanu obiektów (ang. Structural Health Monitoring - SHM). Jednakże większość autorów skupia się na wykrywaniu uszkodzeń i innymi czynnościami związanymi z diagnostyką. Tymczasem, klasyczny, pełny układ monitoringu powinien posiadać poza modułem diagnostycznym również moduł odpowiedzialny za rejestrację wymuszeń. Wymuszenia te mogą być mierzone, lecz taniej i łatwiej niejednokrotnie jest identyfikować je na podstawie pomiaru odpowiedzi. Często jest to jedyna praktyczna możliwość monitorowania wymuszeń. Autorzy podjęli ten często pomijany problem, dokonując porównania najpopularniejszych algorytmów identyfikacji wymuszeń działających w dziedzinie czasu pod kątem ich przydatności w układach SHM. Pokazano zarówno opis metod jak i wyniki ich symulacyjnej weryfikacji. Porównywano następujące cechy algorytmów: dokładność odtwarzania wymuszenia, prostota algorytmu z uwzględnieniem implementacji, czasu działania i rodzaju danych koniecznych do przygotowania algorytmu.
Źródło:
Diagnostyka; 2012, 3(63); 27-34
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 2: Small Normalised Voltage Command
Autorzy:
Reznikov, Boris
Ruderman, Alex
Galanina, Valentina
Powiązania:
https://bibliotekanauki.pl/articles/1193863.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
4-level DC–DC converter
flying capacitor
natural balancing
transients
Opis:
A 4-level flying capacitor converter (FCC) operation is considered on a base of discrete state-space model. A transition matrix is obtained for a pulse width modulation (PWM) period for small normalised voltage command values [0, 1/3]. The transition matrix elements are expanded into power series by small parameters. The matrix eigenvalues are presented in the form of power series as well. Six separate transients are constructed for six possible initial FCC states on a PWM period. Inductor current and capacitors’ voltage transients are found for the voltage source power-up as the arithmetic average of the six separate transients. Finally, the discrete solutions are replaced by equivalent continuous ones. Simple and accurate formulas for inductor current and capacitors’ voltage transients demonstrate good agreement with simulation results.
Źródło:
Power Electronics and Drives; 2020, 5, 40; 41-57
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 1: Large Normalised Voltage Command
Autorzy:
Reznikov, Boris
Ruderman, Alex
Galanina, Valentina
Powiązania:
https://bibliotekanauki.pl/articles/1193906.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
4-level DC-DC converter
flying capacitor
natural balancing
transients
Opis:
A 4-level flying capacitor converter (FCC) operation is considered on a base of discrete state-space model. A transition matrix is obtained for a pulse width modulation (PWM) period for large normalised voltage command values [1/3, 1). The transition matrix elements are expanded into power series by small parameters. The matrix eigenvalues are presented in the form of power series as well. Six separate transients are constructed for six possible initial FCC states on a PWM period. Inductor current and capacitors’ voltage transients are found for the voltage source power-up as the arithmetic average of the six separate transients. Finally, the discrete solutions are replaced by equivalent continuous ones. Simple and accurate formulas for inductor current and capacitors’ voltage transients demonstrate good agreement with simulation results.
Źródło:
Power Electronics and Drives; 2020, 5, 40; 27-40
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
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