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EN
The horizontal-to-vertical spectral ratio (HVSR) has been widely used to calculate near-surface site efects including funda mental resonance frequency and soil amplifcation. In this study, we investigated the features of HVSR in order to assess the reliability of this method. The main premise of Nakamura (1989; Nakamura, Y., 2000. Clear identifcation of fundamental idea of Nakamura’s technique and its applications. In: Proceedings of the 12th World Conference on Earthquake Engineer ing. Auckland, New Zealand.) HVSR method is to assume there are little to no amplifcation or de-amplifcation of motion recorded by the vertical component. In this study, we disregarded this assumption and used diferent proposed spectral ratios of earthquake accelerograms to examine and evaluate the accuracy of the HVSR technique. In addition, to increase the accuracy of the results, near-surface attenuation parameter Kappa (K), as an important spectral decay parameter which has infuence on the site efects, has been incorporated in proposed spectral ratios. The efciency of proposed spectral ratios was evaluated using 3948 accelerograms (Includes surface and borehole stations) of 496 earthquakes from 18 KiK-net accelerometery stations of the two regions of Japan with moment magnitudes ranging from 3 to 5. The two selected areas have diferent geological characteristics and diferent site efects parameters. According to the results, The HVSR method is under-determined at stations where the waves are mainly amplifed as they pass through the site. Moreover, in a single sta tion by calculating the amplifcation value on the vertical component, Site efects measurements obtained from surface and borehole data along with classical HVSR technique have a lower mean absolute error than those obtained by using HVSR technique alone.
EN
This paper presents a novel complementary CPWfed slotted microstrip patch antenna for operation at 2.4 GHz, 5.2 GHz and 6.3 GHz frequencies. The primary structure consists of the complementary split ring resonator slots on a patch and the design is fabricated on FR-4 epoxy substrate with substrate thickness of 1.6 mm. The described structure lacks the presence of a ground plane and makes use of a number of circular complementary SRRs along with rectangular slots on the radiating patch. The structure provides a wide bandwidth of around 390 MHz, 470 MHz and 600 MHz at the three bands with return losses of -11.5 dB, -24.3996dB and -24.4226 dB, respectively. The inclusion of the rectangular slots in the CSRR based slot antenna with stairecase structure improved the performance with respect to return loss.
EN
A nanoscale beam model containing defect under the piezoelectricity considering the surface effects and flexoelectricity is established on the framework of Euler-Bernoulli theory. The governing equations of motion and related boundary conditions are derived by using Hamilton’s principle. The imperfect nanobeam is modeled by dividing the beam into two separate parts that are connected by a rotational and a longitude spring at the defect location. Analytical results on the free vibration response of the imperfect piezoelectric nanobeam exhibit that the flexoelectricity and the surface effects are sensitive to the boundary conditions, defect position, and geometry of the nanobeam. Numerical results are provided to predict the mechanical behavior of a weakened piezoelectric nanobeam considering the flexoelectric and surface effects. It is also revealed that the voltage, defect severity, and piezoelectric material have a critical role on the resonance frequency. The work is envisaged to underline the influence of surface effects and flexoelectricity on the free vibration of a cracked piezoelectric nanobeam for diverse boundary conditions. It should be mentioned, despite our R. Sourkiprevious works, an important class of piezoelectric materials used nowadays and called piezoelectric ceramics is considered in the current study.
EN
In the present paper, a pipe integrated resonator that can reduce the space occupation in the engine room will be introduced. A direct comparison with the Helmholtz resonator through the change of the neck will be considered as well, and possible achievement in performance improvement will be presented. In addition to the basic design of the resonator, another(an alternative) design is offered. An alternative solution suits the engine miniaturization concept taking in to account the possibility of supercharger installation. In such a case the engine compartment becomes very narrow and difficulties with the mounting of existing resonators occurs. The finite element analysis is used for the simulations of the flow processes in resonators and perforated tubes. The effects of reduction in discharge noise are reached.
PL
W niniejszym artykule zaprezentowano nową konstrukcję zintegrowanego rezonatora o zmniejszonych wymiarach, która zajmuje mniej przestrzeni w komorze silnika samochodu. Dokonano bezpośredniego porównania nowej konstrukcji o udoskonalonej geometrii z rezonatorem Helmholtza, przewidując polepszenie sprawności urządzenia. Dodatkowo do podstawowej konstrukcji rezonatora zostało zaproponowane rozwiązanie alternatywne. Alternatywne rozwiązanie spełnia wymóg minimalnych wymiarów zintegrowanego rezonatora, umożliwiając jednocześnie instalację sprężarki mechanicznego układu doładowania silnika. W omówionym przypadku przestrzeń komory silnika była by zbyt mała do zamontowania standardowego rezonatora. Wykorzystano metodę elementów skończonych do przyprowadzenia badania symulacyjnego zjawisk przepływowych w rezonatorze oraz rurach perforowanych. Uzyskano efekt zmniejszenia hałasu wskutek odprężenia powietrza w układzie dolotowym.
EN
Strong motion data are essential for seismic hazard assessment. To correctly understand and use this kind of data is necessary to have a good knowledge of local site conditions. Romania has one of the largest strong motion networks in Europe with 134 real-time stations. In this work, we aim to do a comprehensive site characterization for eight of these stations located in the eastern part of Romania. We make use of a various seismological dataset and we perform ambient noise and earthquake-based investigations to estimate the background noise level, the resonance frequencies and amplification of each site. We also derive the Vs30 parameter from the surface shear-wave velocity profiles obtained through the inversion of the Rayleigh waves recorded in active seismic measurements. Our analyses indicate similar results for seven stations: high noise levels for frequencies larger than 1 Hz, well defined fundamental resonance at low frequencies (0.15-0.29 Hz), moderate amplification levels (up to 4 units) for frequencies between 0.15 and 5-7 Hz and same soil class (type C) according to the estimated Vs30 and Eurocode 8. In contrast, the eighth station for which the soil class is evaluated of type B exhibits a very good noise level for a wide range of frequencies (0.0120 Hz), a broader fundamental resonance at high frequencies (~ 8 Hz) and a flat amplification curve between 0.1 and 3-4 Hz.
PL
Dobroć anteny (Q) jest wygodnym parametrem, umożliwiającym porównywanie anten małych w stosunku do długości fali. W artykule zebrano najważniejsze informacje dotyczące tego parametru. Przedstawiono zależność szerokości pasma pracy anteny od dobroci, dolne ograniczenie dobroci (tzw. granicę Chu) oraz zależność dobroci od impedancji wejściowej anteny. Zwrócono uwagę na unikatowe właściwości anten fraktalnych. Przeprowadzono analizę symulacji impedancji promieniowania anten w postaci pierwszych pięciu iteracji drzewa fraktalnego oraz porównanie z ekwiwalentną anteną monopolową o długości równej badanym strukturom. Zastosowano omówioną koncepcję dobroci anteny do oceny przydatności anten z punktu widzenia szerokości pasma. Wskazano na obszary długości elektrycznych (ka) i numery iteracji, gdzie zastosowanie anteny fraktalnej o kształcie drzewa jest najbardziej korzystne. Pokazano też wpływ kolejnych iteracji na częstotliwości rezonansowe anten oraz ich wzajemne stosunki.
EN
The antenna quality factor (Q) is an useful parameter that allows to compare the antennas if the size of an antenna is small regarding the operating wavelength. The paper summarizes the most important information about the Q. The relationship between the Q and a bandwidth, the lower bound of the Q (Chu – limit) as well as the relationship between the Q and the input impedance have been presented. Also, some unique properties of the fractal antennas have been outlined. The paper also refers to the analysis of simulations of the fractal antennas radiation impedance. The geometry of tested antennas is based on the first five iterations of the fractal tree. The antenna analysis results with monopole of the same length have been compared. The idea of using the Q factor to compare the possible bandwidth of the antennas has been applied. As a results the area of the best electrical length ‘ka’ as well the proper iteration number has been shown. Also an influence of the iteration number on the antenna resonant frequencies has been presented.
PL
W artykule przedstawiono wybrane wyniki badań prototypu nowego wielokomórkowego silnika piezoelektrycznego (WSP). Badany silnik jest przeznaczony do zastosowania w układzie sterowania położeniem fotela w pojazdach samochodowych. Koncepcja struktury elektromechanicznej rozważanego WSP bazuje na trzech rezonansowych aktuatorach piezoelektrycznych o modulowanym ruchu obrotowym. Struktura elektromechaniczna każdego z trzech aktuatorów stanowi niezależną "pojedynczą komórkę" (pojedynczy moduł). Przyjęta struktura WSP zapewnia odpowiednie wartości zarówno momentu obrotowego, jak i prędkości obrotowej, wymaganych w układzie sterowania położeniem fotela. Ponadto, zastosowanie WSP umożliwia zbudowanie zintegrowanej struktury, zwiększonej wydajności oraz bezgłośnej pracy w układzie przeniesienia napędu, także obniżenia kosztów produkcji całego układu, a w ogólności obniżenia poziomu zanieczyszczenia środowiska naturalnego. Przedstawione wyniki badań, przeprowadzone metodą analityczną i doświadczalną, obejmują charakterystyki mechaniczne prototypu WSP.
EN
In this paper chosen analysis results of the prototype multicell piezoelectric motor (MPM) have been presented. The prototype MPM is dedicated for control the car seat position. A concept of the electromechanical structure of the considered prototype is based on the three rotating-mode actuators. The electromechanical structure of each actuator has been considered as an independent one – referred to as a "single cell" (single module). The assumed MPM structure generates adequate values of the rotating torque and speed that is required in the control of the car seat position system. Moreover, the application of the MPM enables to built an integrated structure, increased efficiency and low noise performance in the power train system, also a low cost manufacturing of the whole system, and in general a lower pollution of the environment. The research results, carried out using analytical and experimental methods, covered the mechanical characteristics of the prototype MPM.
EN
Acoustic properties of ultrasound (US) contrast agent microbubbles (MB) highly influence sonoporation efficiency and intracellular drug and gene delivery. In this study we propose an acoustic method to monitor passive and excited MBs in a real time. MB monitoring system consisted of two separate transducers. The first transducer delivered over an interval of 1 s US pulses (1 MHz, 1% duty cycle, 100 Hz repetition frequency) with stepwise increased peak negative pressure (PNP), while the second one continuously monitored acoustic response of SonoVue MBs. Pulse echo signals were processed according to the substitution method to calculate attenuation coefficient spectra and loss of amplitude. During US exposure at 50–100 kPa PNP we observed a temporal increase in loss of amplitude which coincided with the US delivery. Transient increase in loss of amplitude vanished at higher PNP values. At higher PNP values loss of amplitude decreased during the US exposure indicating MB sonodestruction. Analysis of transient attenuation spectra revealed that attenuation coefficient was maximal at 1.5 MHz frequency which is consistent with resonance frequency of SonoVue MB. The method allows evaluation of the of resonance frequency of MB, onset and kinetics of MB sonodestruction.
9
Content available A Clamped Bar Model for the Sompoton Vibrator
EN
The sompoton is one of famous traditional musical instruments in Sabah. This instrument consists of several parts with the vibrator being the most important one. In this paper, the vibrator is modeled as a clamped bar with a uniformly distributed mass. By means of this model, the fundamental frequency is analyzed with the use of an equivalent single degree of freedom system (SDOF) and exact analysis. The vibrator is made of aluminum in different sizes and is excited using a constant air jet to obtain its fundamental resonance frequency. The fundamental frequency obtained from the experimental measurement is compared with the theoretical values calculated based on the equivalent SDOF and exact analysis theories. It is found that the exact analysis gives a closer value to the experimental results as compared to the SDOF system. Although both the experimental and theoretical results exhibit the same trend, they are different in magnitude. To overcome the differences in both theories, a correction factor is added to account for the production errors.
EN
Dielectric spectroscopy is a very useful experimental method for liquid crystal investigation. Electrodes made from indium tin oxide (ITO) or gold are widely used in measuring cells. During the dielectric spectroscopy measurements performed for smectic liquid crystalline mixture it was found that detection of some important relaxation modes in paraelectric SmA*, ferroelectric SmC* and antiferroelectric SmCA* phases for frequencies higher than 0.2–0.5 MHz is not possible. The measuring setup does not allow us to measure such relaxations due to its own dielectric response covering the dielectric response of liquid crystalline medium. One can observe the spurious contribution for high frequency part of the dielectric spectrum, due to non-zero resistivity of electrode material or non-zero inductivity of connecting wires. In this paper, the new model was introduced. Its final equations show how to calculate parameters of relaxations observed in liquid crystals, from dielectric response of the empty and filled measuring cell. The experimental proof of strong influence of measuring setup properties on effective (measured) values of dielectric permittivities was shown.
EN
Numerical analysis is a basic tool for the engineer. Over the years many methods have been developed which turned out to be more or less universal in applications. In the approach to the problem of machine vibration damping based on the machine model, many approximate calculation methods must be used or combined so as to benefit from their advantages and eliminate possible weak points. The hybrid method, developed as a combination of a deformable finite elements method and the dynamics of multi-link systems, was used in the study as one of the tools for vibrating screen's dynamic state diagnostic. The exemplary application of numerical modelling to the issue of multidirectional optimization of an effective machine vibration isolation at the design stage is presented.
PL
Analiza numeryczna stanowi podstawowe narzędzie inżyniera. Na przestrzeni lat powstało wiele metod, które okazały się w zastosowaniach mniej lub bardziej uniwersalne. Podejście do zagadnienie tłumienia drgań maszyny w oparciu o jej model wymaga stosowania wielu metod obliczeń przybliżonych lub ich łączenia w sposób umożliwiający wykorzystanie zalet każdej z nich oraz wyeliminowanie ewentualnych wad. Metoda hybrydowa powstała z połączenia metody odkształcalnych elementów skończonych i dynamiki układów wieloczłonowych została wykorzystana w pracy jako jedno z narzędzi diagnozowania stanu dynamicznego przesiewacza wibracyjnego. Pokazany został przykład zastosowania modelowania numerycznego do zagadnienie wielokierunkowej optymalizacji przy opracowaniu skutecznej wibroizolacji maszyny.
PL
W artykule opisano jeden z bardziej znanych i zbadanych efektów w ciele człowieka, powodowany szybkozmiennym polem elektromagnetycznym. Wskazano na czynniki decydujące o ilości pochłanianego promieniowania, które bardzo często nie są uwzględniane przy rozpatrywaniu tego zagadnienia. Opisano następstwa efektów termicznych oraz sposoby ochrony przed mikrofalami.
EN
One of the best known and investigated effects in the human body induced by the quick-variable electromagnetic field has been described in the paper. At the same time, some factors have been shown which determine the amount of absorbed radiation but often they are not taken into consideration when this problem is being examined. The consequences of thermal effects and some possibilities for protecting people against microwaves have also been described.
PL
W artykule zaprezentowano ośmiokanałowy system pomiarowy do badań matryc bioczujników. Jako biosensory zastosowano rezonatory kwarcowe w roli precyzyjnych mikrowag. System składał się z przedwzmacniaczy dla sygnałów odpowiedzi elektrycznej z rezonatorów oraz przetwornika wartości skutecznej sygnału przemiennego na sygnał stały. Tor sygnałowy układu pomiarowego był analogowy, natomiast jego parametry nastawiane były w sposób cyfrowy. W artykule przedstawiono wyniki wstępnych kalibracji systemu oraz testowe pomiary.
EN
In this article 8-channel measurement device for biosensors arrays is presented. Quartz tuning forks are used as precision mass-sensitive detector. Our measurement setup consisted of quartz tuning forks preamplifiers and RMS to OC converters. The signal path was fully analogue but with digitally controlled parameters (e.g. gain, offset). We also presented calibration procedure and preliminary results of different biomolecular masses detections.
PL
W artykule przedstawiono algorytm dostrajania oraz śledzenia częstotliwości rezonansowej, ultradźwiękowego zespołu drgającego dużej mocy, w systemie zgrzewania ultradźwiękowego z cyfrowym sprzężeniem zwrotnym. Algorytm wykorzystuje wyniki pomiarów impedancji zespołu drgającego do realizacji cyfrowego sprzężenia zwrotnego.
EN
In the paper an algorithm of tuning and tracking the resonance frequency of the high power ultrasonic assembly, in the ultrasonic welding system with digital feedback, has been presented. The algorithm takes advantage of ultrasonic assembly impedance measurements to realize the digital feedback.
15
Content available remote Effect of surface modification of [alfa]-Ti on internal friction
EN
The measurements of the internal friction were done using the RAK -3 relaxator at the bending mode oscillation of the acoustic frequency. The annealed a-Ti and a-Ti with the surface modified by the pulse mechanical grinding, by the plasma assisted formation of the layer of Ti-AI intermetallics and by the electrochemical hydrogen charg-ing have been studied. The Young modulus and the attenuation of samples were measured at the heating of specimens between 200 and 600 K. In the studied temperature range, some relaxation processes occurred in the modified specimens. The values of the Young modulus and of the internal friction background have been also found to depend on the state of the Ti surface. The possible effects of the phase composition and the stress state on the obtained results have been discussed.
PL
Wyznaczanie parametrów sztywności owych i masowych modelu dla zadanych częstotliwości rezonansowych i częstotliwości antyrezo nans owych projektowanego układu jest nadwymiarowym, nieliniowym zadaniem optymalizacyjnym. W artykule do rozwiązania tego typu zadania zastosowano metodę algorytmów genetycznych.
EN
The problem of constructing a mass-spring system with prescribed resonance and anti-resonance frequencies is an over-determined problem. The nature of this problem requires the use of non-linear optimization methods. In this paper the genetic algorithm (GA) method is applied to soltion of such optimization problem.
17
Content available remote Lokalizacja dodatkowej masy w układzie drgającej płyty
EN
This paper presents the application of Artificial Neural Networks [1,2] for solution of an inverse problem. Based on the dynamic characteristics of a plate, the neural identification of parameters of additional mass have been performed. Emphasis was placed on the effective preparation of learning data, which were obtained by experiment.
PL
Zaprezentowano analizę i sposób wyznaczania częstotliwości rezonansowych obudów układów mikrofalowych. Przedstawiono symulację elektromagnetyczną wnęki z przegrodą oraz dużą płaszczyzną dielektryka. Opisano realizację wytłumienia częstotliwości rezonansowych oraz zasady projektowania wnęk.
EN
Box modes analysis is used in conjunction with EM-simulation of partitioned box. The resonance frequency muffle realization is presented together with box design aspect.
19
Content available remote Możliwości pomiaru parametrów cieczy za pomocą czujników ultradźwiękowych
PL
Przedstawiono zasady działania i konstrukcję czujnika lepkości cieczy na bazie rezonatora kwarcowego cięcia AT oraz wyniki badania zachowania czujnika w cieczach o różnej lepkości, oraz praktyczne wyniki prób wykorzystania czujnika do oceny jakości mleka.
EN
In the paper there are presented principles of acting and construction of viscosity sensor on the basis of AT-cut quartz resonator. There are also presented results of sensor frequency and resistance measurement in dependence on viscosity of liquid and results of practical test of sensor as milk quality tester.
EN
Investigations on the influence of the PbTiO3 content on the crystalline and domain structure of PZT-based four-component solid solutions have been performed. It has been shown that there is a close relation between the structure and temperature stability of the resonance frequency (fr) of the fabricated piezoceramic transducers. Better and more stable results have been obtained by doping and modifying the basic chemical composition obtaining Pb(Zr1-x Tix)O3. The compositions with minimal Δ fr / fr, within the temperature range T = 213–358 K (in relation to room temperature Tr = 293 K), exhibited (i) the smallest internal friction (Q-1m), (ii) the highest mechanical quality (Qm), (iii) high values of spontaneous deformation of the elementary cell (δT and δRe), (iv) the complex a-c-domain structure in the tetragonal phase (T) and the simple domain structure in the rhombohedral phase (Re). The practical result of the present work was the fabrication of piezoceramic electric band filters exhibiting Δ fr / fr < 0.2% and a high mechanical quality factor (Qm = 3225).
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