Some aspects of advanced application for fractional wavelet transfrom in the real life applications

The principle of intelligent material or construction diagnosis and its application prospects in structural properties detection (e.g. damage, fatigue, damping) is based on the on structural dynamic characteristic parameters. The system response is evaluated by vibro-acoustic signals and is usually very short and noisy. The new recently developed fractional wavelet transform technique offers very handy tool to perform the signal analysis for pattern, feature search - especially in denoising, spike removal and compression of data set. Presented are the advantages of the fractional wavelet over the rest of the conventional (Fourier transformation) signal analysis techniques as well as other wavelet analysis techniques in the real life applications (e.g. constructions, material crack, and damping

Structural health monitoring with advanced nondestructive methods based on wavelet analysis

Steel structures, especially if they are exposed to the demanding loading or environmental conditions, need to be monitored concerning the actual in-service properties. For reliable monitoring it is important to know the initial properties in order to diagnose possible degradation with time. The target result of the presented research is to develop and apply the procedure for the degradation identification. The obtained results would serve as input for the model analysis that enables estimation of the structure condition and to support decision on the maintenance activities. In the experimental part of the presented research the model of the steel bridge was made to analyze the anomalous structural behavior and to optimize the selection of the appropriate monitoring methods. Various static and dynamic loads have been utilized on the model, with intentionally inserted steel structure failures (e.g. cracked bar, loosened screw joint). The structural responses are very well suited for the wavelet transforms and related wavelet analysis. This paper presents the procedure to correlate results of the wavelet analysis with the inflicted failures within the structure

Destruction of chemical warfare surrogates using a portable atmospheric pressure plasma jet

Today’s reality is connected with mitigation of threats from the new chemical and biological warfare agents. A novel investigation of cold plasmas in contact with liquids presented in this paper demonstrated that the chemically reactive environment produced by atmospheric pressure plasma jet (APPJ) is potentially capable of rapid destruction of chemical warfare agents in a broad spectrum. The decontamination of three different chemical warfare agent surrogates dissolved in liquid is investigated by using an easily transportable APPJ. The jet is powered by a kHz signal source connected to a low-voltage DC source and with He as working gas. The detailed investigation of electrical properties is performed for various plasmas at different distances from the sample. The measurements of plasma properties in situ are supported by the optical spectrometry measurements, whereas the high performance liquid chromatography measurements before and after the treatment of aqueous solutions of Malathion, Fenitrothion and Dimethyl Methylphosphonate. These solutions are used to evaluate destruction and its efficiency for specific neural agent simulants. The particular removal rates are found to be from 56% up to 96% during 10 min treatment. The data obtained provide basis to evaluate APPJ’s efficiency at different operating conditions. The presented results are promising and could be improved with different operating conditions and optimization of the decontamination process

Effect of change selectivity for sensing element made of multi-wall carbon nanotube network treated by plasma

Multiwall carbon nanotubes (MWCNT) network called "Buckypaper" was made by the vacuum filtration method from MWCNT aqueous suspension. In this way we created multi-wall carbon nanotube (MWCNT) networks featured by randomly entangled pure nanotubes. These networks were applied as gas sensors for organic vapors of ethanol and heptane, polar and nonpolar solvents respectively. The gas response was investigated by electrical resistance measurements. The surface sensitivity and selectivity was then modified by low-temperature reactive surface plasma treatment in different gases. With plasma treatment, we first created the functional groups on the nanotubes surface and latter etch them. These processes changed surface selectivity for detection of organic vapors. The results showed that the MWCNT network electrical resistance increased when exposed to organic solvent vapors. This is reversible process, when removed from the vapors. Therefore, the MWCNT networks show the potential to be used as improved sensing elements for sensitive and selective organic vapor detection in near future

Applying of fractional wavelet transform in signal and image processing

Here, they are presented the advantages of the fractional wavelet over the rest of the conventional (Fourier transformation) signal analysis techniques as well as other wavelet analysis techniques in the technical applications

Applying of fractional wavelet transform in signal and image processing

Here, they are presented the advantages of the fractional wavelet over the rest of the conventional (Fourier transformation) signal analysis techniques as well as other wavelet analysis techniques in the technical applications

Enhancing effect of KMnO4 oxidation of carbon nanotubes network embedded in elastic polyurethane on overall electro-mechanical properties of composite

The effect of functionalization of multiwalled carbon nanotubes using KMnO4 oxidation and oxygen plasma treatment on the electrical resistance of nanotube network/polyurethane composite subjected to elongation has been studied. The layered composite is prepared by taking a non-woven polyurethane filtering membrane which is made by electrospinning, enmeshing it with carbon nanotubes and melding them into one. The testing has shown tenfold composite resistance increase for the composite prepared from KMnO4 oxidized nanotubes in comparison to the network prepared from pristine nanotubes. The evaluated sensitivity of the treated composite in terms of the gauge factor increases linearly with strain from values around five at the start of deformation to nearly 45 at the strain 12%. This is a substantial increase, which put the composite prepared from KMnO4 oxidized nanotubes among ranges the materials and strain gauges with the highest sensitivity of electrical resistance measurement. © 2013 Elsevier Ltd

Plasma treatment as a way of increasing the selectivity of carbon nanotube networks for organic vapor sensing elements

Multi-walled carbon nanotubes networks (MWCNTs) were used as a layer for organic vapor detection. The sensor detects volatile organic compounds (VOC). The gas sensing by MWCNTs is measured by means of macroscopic electrical resistance. The selected solvents had different polarities and volume fractions of saturated vapors. The electrical resistance of MWCNTs increases when exposed to organic solvent vapors, and a reversible reaction is observed when the MWCNT is removed from the vapors. The MWCNTs were modified by means of plasma treatment. For modifications RF plasma in O-2 at 50 Pa and an afterglow configuration were used. The modified MWCNTs show an increase in sensitivity caused by creating carboxylic groups on the surface of the carbon nanotubes. It leads, for example, to enhancement of the sensitivity from usual 30 % for heptane at RT to more than 200% after plasma treatment in O-2 for 10s

Modified atmospheric CO2_2 levels for maintenance of fruit weight and nutritional quality upon long-term storage in blueberry (Vaccinium corymbosum L.) \u27Liberty\u27

Blueberry fruits have gained consumer attention in recent years due to their good taste and high nutritional value. However, the short shelf-life of the fruit is one of the main downsides in intensive blueberry production. Therefore, optimized storage technology with a modified atmosphere is necessary to prolong blueberry fruit quality on the market. The aim of this study was to investigate long-term storage of fruit of the highbush blueberry (Vaccinium corymbosum L.) ‘Liberty’ under the air control (0.5% CO$_2$, 19.5% O$_2$, 80% N$_2$) and controlled atmosphere conditions of: 5% CO$_2$, 5% O$_2$, 90% N$_2$15% CO$_2$, 5% O$_2$, 80% N$_2$and 25% CO$_2$, 5% O$_2$, 70% N$_2$. Fruit sampling was performed four times during storage (17, 30, 44, 62 days). Evaluation was carried out for fruit weight, total and individual sugar and organic acid contents, sugar-to-organic acid ratio, and individual phenolics contents. After 44 days of storage, weight loss was highest with 15% CO$_2$ and lowest with 5% CO$_2$, with minor variations. The greatest breakdown of total sugars was seen for the air control, and the least for 25% CO$_2$. Organic acids were significantly reduced under all of these storage conditions. Consequently, a high sugar-to-organic acid ratio was maintained in fruit stored with 25% CO$_2$. The contents of all of the identified phenolics significantly decreased with 15% and 25% CO$_2$. After 62 days of storage with 5% CO$_2$, there were small decreases in flavan-3-ols and hydroxycinnamic acids, while flavonoid and anthocyanin contents were unchanged, or for some individual phenolics, content increased. These data show that 15% CO$_2$ or higher accelerates degradation of the phenolics. We can conclude that for maintenance of weight and nutritional quality of the blueberry fruit ‘Liberty’, the optimal controlled atmosphere under long-term storage is 5% CO$_2$, 5% O$_2$, and 90% N$_2$