Browse

You are looking at 71 - 80 of 1,383 items for :

  • Control Engineering, Metrology and Testing x
Clear All
Open access

Jiří Přibil, Anna Přibilová and Ivan Frollo

Abstract

The paper focuses on two methods of evaluation of successfulness of speech signal enhancement recorded in the open-air magnetic resonance imager during phonation for the 3D human vocal tract modeling. The first approach enables to obtain a comparison based on statistical analysis by ANOVA and hypothesis tests. The second method is based on classification by Gaussian mixture models (GMM). The performed experiments have confirmed that the proposed ANOVA and GMM classifiers for automatic evaluation of the speech quality are functional and produce fully comparable results with the standard evaluation based on the listening test method.

Open access

Przemysław Gilski and Jacek Stefański

Abstract

In the age of digital media, delivering broadcast content to customers at an acceptable level of quality is one of the most challenging tasks. The most important factor is the efficient use of available resources, including bandwidth. An appropriate way of managing the digital multiplex is essential for both the economic and technical issues. In this paper we describe transmission quality measurements in the DAB+ broadcast system. We provide a methodology for analysing parameters and factors related with the efficiency and reliability of a digital radio link. We describe a laboratory stand that can be used for transmission quality assessment on a regional and national level.

Open access

Piotr Martyniuk, Małgorzata Kopytko, Paweł Madejczyk, Aleksandra Henig, Kacper Grodecki, Waldemar Gawron and Jarosław Rutkowski

Abstract

The paper reports on a long-wave infrared (cut-off wavelength ~ 9 μm) HgCdTe detector operating under nbiased condition and room temperature (300 K) for both short response time and high detectivity operation. The ptimal structure in terms of the response time and detectivity versus device architecture was shown. The response time of the long-wave (active layer Cd composition, xCd = 0.19) HgCdTe detector for 300 K was calculated at a level of τs ~ 1 ns for zero bias condition, while the detectivity − at a level of D* ~ 109 cmHz1/2/W assuming immersion. It was presented that parameters of the active layer and P+ barrier layer play a critical role in order to reach τs ≤ 1 ns. An extra series resistance related to the processing (RS+ in a range 5−10 Ω) increased the response time more than two times (τs ~ 2.3 ns).

Open access

Jana Jablonská, Miroslav Mahdal and Milada Kozubková

Abstract

The article deals with experimental investigation of water cavitation in the convergent-divergent nozzle of rectangular cross-section. In practice, a quick and simple determination of cavitation is essential, especially if it is basic cavitation or cavitation generated additionally by the air being sucked. Air influences the formation, development and size of the cavity area in hydraulic elements. Removal or reduction of the cavity area is possible by structural changes of the element. In case of the cavitation with the suction air, it is necessary to find the source of the air and seal it. The pressure gradient, the flow, the oxygen content in the tank, and hence the air dissolved in the water, the air flow rate, the noise intensity and the vibration velocity on the nozzle wall were measured on laboratory equipment. From the selected measurements the frequency spectrum of the variation of the water flow of the cavity with cavitation without air saturation and with air saturation was compared and evaluated.

Open access

Jie Chen, Jie Liu, Xingrui Wang, Longfei Zhang, Xiao Deng, Xinbin Cheng and Tongbao Li

Abstract

Pitch uncertainty and line edge roughness are among the critical quality attributes of a pitch standard and normally the analyses of these two parameters are separate. The analysis of self-traceable Cr atom lithography nano-gratings shows a positive relevance and sensitivity between LER and evaluated standard deviation of pitch. Therefore, LER can be used as an aided pre-evaluation parameter for the pitch calculation method, such as the gravity center method or the zero-crossing points method. The optimization of the nano-grating evaluation method helps to obtain the accurate pitch value with fewer measurements and provide a comprehensive characterization of pitch standards.

Open access

Krzysztof Mleczko, Piotr Ptak, Zbigniew Zawiślak, Marcin Słoma, Małgorzata Jakubowska and Andrzej Kolek

Abstract

Graphene is a very promising material for potential applications in many fields. Since manufacturing technologies of graphene are still at the developing stage, low-frequency noise measurements as a tool for evaluating their quality is proposed. In this work, noise properties of polymer thick-film resistors with graphene nano-platelets as a functional phase are reported. The measurements were carried out in room temperature. 1/f noise caused by resistance fluctuations has been found to be the main component in the specimens. The parameter values describing noise intensity of the polymer thick-film specimens have been calculated and compared with the values obtained for other thick-film resistors and layers used in microelectronics. The studied polymer thick-film specimens exhibit rather poor noise properties, especially for the layers with a low content of the functional phase.

Open access

Jarosław Glapiński and Ireneusz Jabłoński

Abstract

A complex model of mechanically ventilated ARDS lungs is proposed in the paper. This analogue is based on a combination of four components that describe breathing mechanics: morphology, mechanical properties of surfactant, tissue and chest wall characteristics. Physical-mathematical formulas attained from experimental data have been translated into their electrical equivalents and implemented in MultiSim software. To examine the adequacy of the forward model to the properties and behaviour of mechanically ventilated lungs in patients with ARDS symptoms, several computer simulations have been performed and reported in the paper. Inhomogeneous characteristics observed in the physical properties of ARDS lungs were mapped in a multi-lobe model and the measured outputs were compared with the data from physiological reports. In this way clinicians and scientists can obtain the knowledge on the moment of airway zone reopening/closure expressed as a function of pressure, volume or even time. In the paper, these trends were assessed for inhomogeneous distributions (proper for ARDS) of surfactant properties and airway geometry in consecutive lung lobes. The proposed model enables monitoring of temporal alveolar dynamics in successive lobes as well as those occurring at a higher level of lung structure organization, i.e. in a point P0 which can be used for collection of respiratory data during indirect management of recruitment/de-recruitment processes in ARDS lungs. The complex model and synthetic data generated for various parametrization scenarios make possible prospective studies on designing an indirect mode of alveolar zone management, i.e. with

Open access

Arkadiusz Szewczyk

Abstract

A developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

Open access

Jacek Majewski

Abstract

Polymer-based capacitive humidity sensors emerged around 40 years ago; nevertheless, they currently constitute large part of sensors’ market within a range of medium (climatic and industrial) humidity 20−80%RH due to their linearity, stability and cost-effectiveness. However, for low humidity values (0−20%RH) that type of sensor exhibits increasingly nonlinear characteristics with decreasing of humidity values. This paper presents the results of some experimental trials of CMOS polymer-based capacitive humidity sensors, as well as of modelling the behaviour of that type of sensor. A logarithmic functional relationship between the relative humidity and the change of sensor output value at low humidity is suggested.

Open access

Aimé Lay-Ekuakille, Giuseppe Griffo, Paolo Visconti, Patrizio Primiceri and Ramiro Velazquez

Abstract

Detection of leakages in pipelines is a matter of continuous research because of the basic importance for a waterworks system is finding the point of the pipeline where a leak is located and − in some cases − a nature of the leak. There are specific difficulties in finding leaks by using spectral analysis techniques like FFT (Fast Fourier Transform), STFT (Short Term Fourier Transform), etc. These difficulties arise especially in complicated pipeline configurations, e.g. a zigzag one. This research focuses on the results of a new algorithm based on FFT and comparing them with a developed STFT technique. Even if other techniques are used, they are costly and difficult to be managed. Moreover, a constraint in the leak detection is the pipeline diameter because it influences accuracy of the adopted algorithm. FFT and STFT are not fully adequate for complex configurations dealt with in this paper, since they produce ill-posed problems with an increasing uncertainty. Therefore, an improved Tikhonov technique has been implemented to reinforce FFT and STFT for complex configurations of pipelines. Hence, the proposed algorithm overcomes the aforementioned difficulties due to applying a linear algebraic approach.