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Number of results: 17
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Abstract

Simultaneous propagation of vibrations and noise has an important role in the task of minimizing vibroacoustic hazards on the station of operator of the construction machinery. In many cases vibrations transferred by the construction are processed to noise in different points of the machine. As a result, they may increase the level of noise at the workplace. The paper presents the proposition of a simple estimation of noise and vibration propagation paths of the machine. On the basis of the analysis of hydraulic excavator an effectiveness of a proposed procedure was shown. This procedure helps to minimize the transfer of vibrations of power unit in selected frequency ranges which led to the change of overall noise level in operator’s cab about 5 dB.
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Authors and Affiliations

Zbigniew Dąbrowski
Jacek Dziurdź
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Abstract

In a television, obtaining a good acoustic response is a challenging issue because of slim mechanical structures. The area dedicated for speaker’s placement is limited and inadequate space inside the cabinet of a TV prevents possible solutions to increase the sound performance. In addition, frame of the TV’s is getting narrower as the customers searching for the highest screen to body ratio. These designing aspects restrain optimal speaker positioning to achieve good sound performance. In this paper, an analysis related to speaker’s placement and mounting angle is proposed. A rotation setup compatible with a TV was prepared to measure different facing position of the speaker. This paper proposes the analysis of speaker’s rotation and facing direction in a flat panel television and its effects on sound pressure level together with deviation of the acoustic response. Measurement results are analyzed with an audio analyzer together with a statistics tool to achieve precise results.
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Authors and Affiliations

Ibrahim Demirel
1

  1. Arçelik AS., Electronics HW Design, Turkey
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Abstract

This paper presents the measurement of vibrational properties of sundatang soundboard. Sundatang is a plucked stringed traditional musical instrument that is popular among the Kadazandusun communities in Sabah, Malaysia. The vibrational properties of the soundboard are measured using CADA-X impact hammering system in a condition where the instrument is without any string. There are two types of sundatang used in this study; one made from acacia and the other from vitex wood. In this measurement, frequency response functions (FRFs) and modal parameters of the top plate and back plate of this instrument are obtained. It is found that in free edge, fundamental frequency of both plates of acacia sundatang is greater than the vitex sundatang in a range of 112 Hz to 230 Hz. However, in clamped edge (attached to its ribs), it was modified to a lower frequency and closer to each other in the range of 55 Hz to 59 Hz. Another finding is the detection of the excitation of similar mode shape at different resonance frequencies. This phenomenon is termed as Different State of Mode (DSM) which is observed may be because the number of testing points is not enough. Findings of this study provide important information to the study of quality development of this instrument

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Authors and Affiliations

Ronald Yusri Batahong
Jedol Dayou
Semyung Wang
Jongsuh Lee
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Abstract

This paper presents the method of analysis of parametric systems in frequency domain. These systems are also referred to as linear time varying systems (LTV). The article includes a description of an analytical method for determining the frequency response of the first order parametric circuit with non-periodically variable parameters. The results have been illustrated by an example.

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Authors and Affiliations

Anna Piwowar
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Abstract

The paper presents theoretical and experimental analyses of a possible effect of the short-circuit forces on the transformer winding. The first part of the paper is focused on creation and activity of the radial and axial forces during a short circuit. It shows dimensions, direction and − of course − the resulting mechanical stress. The presented equation shows basic dependencies of these mechanical forces created in the transformer winding. Finally, the paper presents experimental methods of diagnosing and analysing the effects of short-circuit forces on the transformer winding.

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Authors and Affiliations

Miroslav Gutten
Richard Janura
Milan Šebök
Daniel Korenčiak
Matej Kučera
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Abstract

Thin plates, in the form of individual panels or whole device casings, often separate the noise source from its recipients. It would be very desirable if the panels could effectively block the sound transmission preventing noise from further propagation. This is especially challenging to achieve at low frequencies. A promising approach, intensively developed in the recent years, is to employ active control methods by adding sensors and actuators, and running a control algorithm. However, if the noise is narrow-band, an alternative passive solution originally developed by the authors can be applied. It is based on appropriately located passive elements which can be used to alter the frequency response of the vibrating structure thus improving its sound insulation properties. Such an approach is referred to as the frequency response shaping method. The purpose of this paper is to further develop this method and apply it to a device casing panel. The efficiency of the method is evaluated by simulation and real experiments. Appropriate cost functions and mathematical models are formulated and used to optimise the arrangement of passive elements mounted to the plate, enhancing its sound insulation properties at the given frequency range. The results are reported, and advantages and limits of the method are pointed out and discussed.

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Authors and Affiliations

Stanisław Wrona
Krzysztof Mazur
Jaroslaw Rzepecki
Anna Chraponska
Marek Pawelczyk
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Abstract

With the rapid advancement of digital processors, filters have been commonly implemented using microcomputers. In this study, a low-cost and compact Arduino Uno development board was used to realize digital lead and lag compensators. Arduino boards are very affordable. Consequently, they were investigated to see if they were capable of preserving the frequency response of continuous-time compensators. The experiments required a set of equipment including a function generator, an Arduino Uno development board, a PC-based oscilloscope, and a laptop. The signal frequency was varied from 0 to 500 Hz. Two discretization methods were employed, namely bilinear transformation and matched pole-zero mapping. The results showed that an Arduino Uno board can be utilized to implement lead and lag compensators to some extent. The discrete-time compensator preserved the capability of filtering out certain frequencies. The change in DC gain was negligible, however, there was a significant difference in the cut-off frequency and transient slope. For both discretization methods, the frequency responses at high frequency experienced a rippling profile.

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Authors and Affiliations

Gunawan Dewantoro
Irwin Shauma Rizky
Budihardja Murtianta
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Abstract

In Polish coal mining, medium voltage power distribution networks operate with an insulated neutral point. Zero-sequence current transformers are the basic sensors that generate input signals for earth-fault protection relays. In the literature, the problem of frequency response analysis of various types of current transformers has been examined many times, e.g. [1] [2], but not for zero-sequence current transformers so far. As part of the work, two types of zero-sequence current transformers in the range from 0.1 Hz to 100 kHz were tested. Both the change of the current ratio and the angular shift between the transformer secondary current and the total primary current were analyzed.

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Authors and Affiliations

Krzysztof Kuliński
Adam Heyduk
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Abstract

In this work, an approach to the design of broadband thickness-mode piezoelectric transducer is pre- sented. In this approach, simulation of discrete time model of the impulse response of matched and backed piezoelectric transducer is used to design high sensitivity, broad bandwidth, and short-duration impulse response transducers. The effect of matching the performance of transmitting and receiving air backed PZT-5A transducer working into water load is studied. The optimum acoustical characteristics of the quarter wavelength matching layers are determined by a compromise between sensitivity and pulse duration. The thickness of bonding layers is smaller than that of the quarter wavelength matching layers so that they do not change the resonance peak significantly. Our calculations show that the −3 dB air backed transducer bandwidth can be improved considerably by using quarter wavelength matching layers. The computer model developed in this work to predict the behavior of multilayer structures driven by a transient waveform agrees well with measured results. Furthermore, the advantage of this this model over other approaches is that the time signal for optimum set of matching layers can be predicted rapidly
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Authors and Affiliations

Mohamed G.S. Ali
Nour Z. Elsayed
Ebtsam A. Eid
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Abstract

One of important methods used for diagnostics of a transformer’s active part is Frequency Response Analysis (FRA). It allows to determine the mechanical condition of windings, their displacements, deformations and electric faults, as well as some problems with internal leads and connections, core and bushings. Still pending problem is interpretation of measurements results. One of approaches is application of computer modeling to simulate various failure modes and connected with them changes in FRA response. The paper presents two types of models, one based on lumped parameters with RLC elements, and one based on distributed parameters with TLM method. Both methods give similar results, comparable to real measurements of simulated coil.

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Authors and Affiliations

K.M. Gawrylczyk
S. Banaszak
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Abstract

The equipment mounted on the carbody chassis of the railway vehicles is a critical component of the vehicle in terms of ride comfort. The reason for that is their large mass, able to visibly influence the vibrations mode of the carbody. The paper examines the influence of the equipment upon the mode of vertical vibrations of the carbody in the high-speed vehicles, reached on the basis of the frequency response functions of the acceleration in three carbody reference points – at the centre and above the bogies. These functions are derived from the numerical simulations developed on a rigid-flexible coupled model, with seven degrees of freedom. As a rule, the results herein prove the influence of the equipment mounting mode (rigid or elastic), along with the speed regime, upon the level of vibrations in the carbody reference points, at the resonance frequency of the symmetrical bending mode. Similarly, it is also demonstrated how the equipment mass and the damping degree of the suspension system affect the level of the vibrations in the carbody.

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Authors and Affiliations

Mădălina Dumitriu
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Abstract

Analytical design of the PID-type controllers for linear plants based on the magnitude optimum criterion usually results in very good control quality and can be applied directly for high-order linear models with dead time, without need of any model reduction. This paper brings an analysis of properties of this tuning method in the case of the PI controller, which shows that it guarantees closed-loop stability and a large stability margin for stable linear plants without zeros, although there are limitations in the case of oscillating plants. In spite of the fact that the magnitude optimum criterion prescribes the closed-loop response only for low frequencies and the stability margin requirements are not explicitly included in the design objective, it reveals that proper open-loop behavior in the middle and high frequency ranges, decisive for the closed-loop stability and robustness, is ensured automatically for the considered class of linear systems if all damping ratios corresponding to poles of the plant transfer function without the dead-time term are sufficiently high.
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Authors and Affiliations

Jan Cvejn
1

  1. University of Pardubice, Faculty of Electrical Engineering and Informatics, Studentska 95, 532 10 Pardubice, Czech Republic
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Abstract

Specific requirements are designed and implemented in electronic and telecommunication systems for received signals, especially high-frequency ones, to examine and control the signal radiation. However, as a serious drawback, no special requirements are considered for the transmitted signals from a subsystem. Different industries have always been struggling with electromagnetic interferences affecting their electronic and telecommunication systems and imposing significant costs. It is thus necessary to specifically investigate this problem as every device is continuously exposed to interferences. Signal processing allows for the decomposition of a signal to its different components to simulate each component. Radiation control has its specific complexities in systems, requiring necessary measures from the very beginning of the design. This study attempted to determine the highest radiation from a subsystem by estimating the radiation fields. The study goal was to investigate the level of radiations received and transmitted from the adjacent systems, respectively, and present methods for control and eliminate the existing radiations.

The proposed approach employs an algorithm which is based on multi-component signals, defect, and the radiation shield used in the subsystem. The algorithm flowchart focuses on the separation and of signal components and electromagnetic interference reduction. In this algorithm, the detection process is carried out at the bounds of each component, after which the separation process is performed in the vicinity of the different bounds. The proposed method works based on the Fourier transform of impulse functions for signal components decomposition that was employed to develop an algorithm for separation of the components of the signals input to the subsystem.

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Authors and Affiliations

Milad Daneshvar
Naser Parhizgar
Homayoon Oraizi
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Abstract

Controlling and reducing the radiation emitted by various systems helps the board designer improve systems’ performance. One proposed way to achieve these goals is to use an algorithm to control the radiation applied to systems. According to the executive structure of the algorithm and considering the nature of the existing signals in several components, the separation of the signal components is on the agenda of the algorithm. In fact, the goal is to create an intuitive view of the multi-component signals around the systems that enter the systems from different angles and have a detrimental effect on their performance. Using signal processing methods, we will be able to break down the signal into different components and simulate each component separately. To prevent high computational repetitions and increase simulation time in signal component analysis, by reducing the components, we reduce the number of mesh cells in the software and, using linear approximation, determine the exact position of the radiation signal applied to systems and thus the best linear relationship. The signal entry path is used to apply the rules required for prediction design.

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Authors and Affiliations

Milad Daneshvar
Nasser Parhizgar
Homayoon Oraizi
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Abstract

Long transmission lines have to be compensated to enhance the transport of active power. But a wrong design of the compensation may lead to subsynchronous resonances (SSR). For studies often park equivalent circuits are used. The parameters of the models are often determined analytically or by a three-phase short-circuit test. Models with this parameters give good results for frequencies of 50 Hz and 100 Hz resp. 60 Hz and 120 Hz. But SSR occurs at lower frequencies what arises the question of the reliability of the used models. Therefore in this publication a novel method for the determination of Park equivalent circuit parameters is presented. Herein the parameters are determined form time functions of the currents and the electromagnetic moment of the machine calculated by transient finite-element simulations. This parameters are used for network simulations and compared with the finite-element calculations. Compared to the parameters derived by a three-phase short-circuit a significant better accuracy of simulation results can be achieved by the presented method.

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Authors and Affiliations

Christian Kreischer
Stefan Kulig
Carsten Göbel
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Abstract

The design of a low complexity multiplier-less narrow transition band filter bank for the channelizer of multistandard software-defined radio (SDR) is investigated in this paper. To accomplish this, the modal filter and complementary filter in the upper and lower branches of the conventional Frequency Response Masking (FRM) architecture are replaced with two power-complementary and linear phase filter banks. Secondly, a new masking strategy is proposed to fully exploit the potential of the numerous spectra replicas produced by the interpolation of the modal filter, which was previously ignored in the existing FRM design. In this scheme, the two masking filters are appropriately modulated and alternately masked over the spectra replicas from 0 to 2π, to generate even and odd channels. This Alternate Masking Scheme (AMS) increases the potency of the Modified FRM (ModFRM) architecture for the design of computationally efficient narrow transition band uniform filter bank (termed as ModFRM-FB). Finally, by combining the adjoining ModFRM-FB channels, Non-Uniform ModFRMFB (NUModFRM-FB) for extracting different communication standards in the SDR channelizer is created. To reduce the total power consumption of the architecture, the coefficients of the proposed system are made multiplier-less using Matching Pursuits Generalized Bit-Planes (MPGBP) algorithm. In this method, filter coefficients are successively approximated using a dictionary of vectors to give a sum-of-power-of-two (SOPOT) representation. In comparison to all other general optimization techniques, such as genetic algorithms, the suggested design method stands out for its ease of implementation, requiring no sophisticated optimization or exhaustive search schemes. Another notable feature of the suggested approach is that, in comparison to existing methods, the design time for approximation has been greatly reduced. To further bring down the complexity, adders are reused in recurrent SOPOT terms using the Common Subexpression Elimination (CSE) technique without compromising the filter performance.
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Authors and Affiliations

A.K. Parvathi
1
V. Sakthivel
1

  1. National Institute of Technology, Calicut, India

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