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An experimental study of thick film strain sensitive resistors as typically employed in resistive bridge interface circuits has been undertaken. It has been found that the chosen aspect ratio (length to width ratio) of these screen printed and fired thick film resistors has a significant effect on both the temperature coefficient of resistance and the low frequency noise characteristics of the devices. This sensitivity to aspect ratio has been attributed to metal end contact migration in the devices during firing and hence a relationship between the sensitivity and the choice of end contact material and the firing regime employed in device fabrication has also been identified.

The paper aims to get the knowledge about electrical properties, including noise, of modern polymer thick-film resistors (TFRs) in a wide range of temperature values, i.e. from 77 K up to room temperature. The sample resistors have been made of different combinations of resistive compositions, either ED7100 or MINICO (M2013, M2010), and conducting pastes (for contacts) Cu- or Au-based, deposited on FR-4 laminate.

The paper opted for an experimental study using either current noise index measurement in room temperature for large batch of samples or noise spectra measurement in temperature range 77-300 K for selected samples. Obtained noise maps, i.e. plots of power spectral density of voltage fluctuations vs frequency and temperature, have been used for evaluation of noise describing parameters like material noise intensity C and figure of merit K, for TFRs made of different combinations of resistive/conductive materials. Comparison of the parameters gives the information about the quality of the technology and matching the conductive/resistive materials.

Experiments confirmed that the main noise component is 1/f resistance noise. However, low-frequency noise spectroscopy revealed that also noise components of Lorentzian shape, associated with thermally activated noise sources exist. Their activation energies have been found to be of a few tenths of eV.

The noise intensity of polymer TFRs depends on technology process and/or contacts materials. The use of Au contacts leads to better noise properties of the resistors. The results of the studies might be helpful for further improvement of thick-film technology, especially for manufacturing low-noise, stable and reliable TFRs.

The paper includes indications for the materials selection for thick-film technology to manufacture low-noise, reliable and stable TFRs.

Experimental studies of electrical properties of polymer TFRs by means of noise spectra measurements in wide range of temperature is rare. They give fundamental knowledge about noise sources in the modern passive electronic components as well as practical indications of selection material for thick-film technology, to obtain high performance components and get technological advantage.

ADVANCES in engine technology are evaluated herein, and, for the purposes of improving future noise evaluation of commercial jet aircraft, adjustments to current evaluation techniques are suggested.

The traditional total variation (TV) models in wavelet domain use thresholding directly in coefficients selection and show that Gibbs' phenomenon exists. However, the nonzero coefficient index set selected by hard thresholding techniques may not be the best choice to obtain the least oscillatory reconstructions near edges. This paper aims to propose an image denoising method based on TV and grey theory in the wavelet domain to solve the defect of traditional methods.

In this paper, the authors divide wavelet into two parts: low frequency area and high frequency area; in different areas different methods are used. They apply grey theory in wavelet coefficient selection. The new algorithm gives a new method of wavelet coefficient selection, solves the nonzero coefficients sort, and achieves a good image denoising result while reducing the phenomenon of “Gibbs.”

The results show that the method proposed in this paper can distinguish between the information of image and noise accurately and also reduce the Gibbs artifacts. From the comparisons, the model proposed preserves the important information of the image very well and shows very good performance.

The proposed image denoising model introducing grey relation analysis in the wavelet coefficients selecting and modifying is original. The proposed model provides a viable tool to engineers for processing the image.

This study aims to carry out numerical modeling to predict aerodynamic noise radiation from four different Savonius rotor blade profile.

Incompressible unsteady reynolds-averaged navier-stokes (URANS) approach using gamma–theta turbulence model is conducted to obtain the time accurate turbulent flow field. The Ffowcs Williams and Hawkings (FW-H) acoustic analogy formulation is used for noise predictions at optimal tip speed ratio (TSR).

The mean torque and power coefficients are compared with the experimental data and acceptable agreement is observed. The total and Mono+Dipole noise graphs are presented. A discrete tonal component at low frequencies in all graphs is attributed to the blade passing frequency at the given TSR. According to the noise prediction results, Bach type rotor has the lowest level of noise emission. The effect of TSR on the noise level from the Bach rotor is investigated. A direct relation between angular velocity and the noise emission is found.

The savonius rotor is a type of vertical axis wind turbines suited for mounting in the vicinity of residential areas. Also, wind turbines wherein operation are efficient sources of tonal and broadband noises and affect the inhabitable environment adversely. Therefore, the acoustic pollution assessment is essential for the installation of wind turbines in residential areas.

This study aims to investigate the radiated noise level of four common Savonius rotor blade profiles, namely, Bach type, Benesh type, semi-elliptic and conventional. As stated above, numbers of studies exploit the URANS method coupled with the FW-H analogy to predict the aeroacoustics behavior of wind turbines. Therefore, this approach is chosen in this research to deal with the aeroacoustics and aerodynamic calculation of the flow field around the aforementioned Savonius blade profiles. The effect of optimal TSR on the emitted noise and the contribution of thickness, loading and quadrupole sources are of interest in this study.

Active noise control (ANC) became in the last decade a very popular technique for controlling low‐frequency noise. The increase in its popularity was a consequence of the rapid development in the fields of computers in general, and more specifically in digital signal processing boards. ANC systems are application specific and therefore they should be optimally designed for each application. Even though the physical background of the ANC systems is well‐known and understood, tools for the optimization of the sensor and actuator configurations of the ANC system based on classical optimization methods do not perform as required. This is due to the nature of the problem that allows the calculation of the effect of the ANC system only when the sensor and actuator configurations are specified. An additional difficulty in this problem is that the sensor and the actuator configurations cannot be optimized independently, since the effect of the ANC system is directly involved in the combined sensor and actuator configuration. For the solution of this problem several intelligent techniques were applied. In this paper the successful application of a genetic algorithm, an optimization technique that belongs to the broad class of evolutionary algorithms, is presented.

This paper aims to assess the aeroacoustic and aerodynamic performance of a morphing airfoil with a flexible trailing edge (FTE). The objective is to make a comparison of the aerodynamic noise characteristics between the conventional airfoil with a flap and morphing airfoil and analyse the noise reduction mechanisms of the morphing airfoil.

The computational fluid dynamic method was used to calculate the aerodynamic coefficients of morphing airfoil and the Ffowcs-Williams and Hawking’s acoustic analogy methods were performed to predict the far-field noise of different airfoils.

Results show that compared with the conventional airfoil, the morphing airfoil can generate higher lift and lower noise, but a greater drag. Additionally, the noise caused by the one-unit lift of the morphing airfoil is significantly lower than that of the conventional airfoil. For the morphing airfoil, the shedding vortex in the trailing edge was the main noise resource. As the angle of attack (AoA) increases, the overall sound pressure level of the morphing airfoil increases significantly. With the increase of the trailing edge deflection angle, the amplitude and the period of sound pressure of the morning airfoil fluctuation increase.

Presented results could be very useful during designing the morphing airfoil with FTE, which has significant advantages in aerodynamic efficiency and aeroacoustic performance.

This paper presents the aerodynamic and aeroacoustic characteristics of the morphing airfoil. The effect of trailing edge deflection angle and AoA on morphing airfoil was investigated. In the future, using a morphing airfoil instead of a traditional flap can reduce the aircraft`s fuel consumption and noise pollution.

The purpose of this paper is to review recent applications of functional magnetic resonance imaging (fMRI) and other neuroimaging techniques in marketing and advertising, and to present some methodological and statistical considerations that should be taken into consideration when applying fMRI to study consumers’ cognitive behavior related to marketing phenomena.

A critical approach to investigate three methodological issues related to fMRI applications in marketing is adopted. These issues deal mainly with brain activation regions, event-related fMRI and signal-to-noise ratio. Statistical issues related to fMRI data pre-processing, analyzing and reporting are also investigated.

Neuroimaging cognitive techniques have great potential in marketing and advertising. This is because, unlike conventional marketing research methods, neuroimaging data are much less susceptible to social desirability and “interviewer’s” effect. Thus, it is expected that using neuroimaging methods to investigate which areas in a consumer’s brain are activated in response to a specific marketing stimulus can provide a much more honest indicator of their cognition compared to traditional marketing research tools such as focus groups and questionnaires.

By merging disparate fields, such as marketing, neuroscience and cognitive psychology, this research presents a comprehensive critical review of how neuroscientific methods can be used to test existing marketing theories.

This paper proposes a useful pseudo‐logarithmic circuit as a basic building block in the construction of a logarithmic amplifier made from piecewise approximations.

The circuit employs two operational and a handful of resistors, and mimics the logarithmic function over a predefined range. Control of the pseudo‐logarithmic function is achieved by a ratio of resistances defined as x, one of which may be digitally switched, or implemented by tunable transconductors. When controlled by digitally switched resistors, the circuit is particularly attractive because of the commercial availability of such resistors, and with the aid of simple control logic, individual blocks can be algebraically summed to extend the dynamic range of the basic pseudo‐logarithmic block which is 28 dB

Experimental results using off the shelf operational amplifiers (opamps) and a handful of resistors show that the circuit yields a maximum log error of 0.6915 dB for x in (0.22, 4.65).

Proposes a novel circuit capable of realizing the pseudo‐logarithmic function (x−1)/(1+x). The circuit is simple and easily implemented using readily available opamps.

Careful cooling tower selection will guarantee great savings on the annual water bill and ensure that refrigeration and air‐conditioning systems are adequately served.