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Ground-penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in nondestructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR has proven its ability to work in electromagnetic frequency range for subsoil investigations, and it is a risk-reduction strategy for surveying underground various targets and their identification and detection. This paper presents the results of a case study which exceeds the laboratory level being realized in the field in a real case where the scanning conditions are much more difficult using GPR signals for detecting and assessing underground drainage metallic pipes which cross an area with large buildings parallel to the riverbed. The two urban drainage pipes are detected based on GPR imaging. This provides an approximation of their location and depth which are convenient to find from the reconstructed profiles of both simulated and practical GPR signals. The processing of data recorded with GPR tools requires appropriate software for this type of measurement to detect between different reflections at multiple interfaces located at different depths below the surface. In addition to the radargrams recorded and processed with the software corresponding to a GPR device, the paper contains significant results obtained using techniques and algorithms of the processing and post-processing of the signals (background removal and migration) that gave us the opportunity to estimate the location, depth, and profile of pipes, placed into a concrete duct bank, under a structure with different layers, including pavement, with good accuracy.

The hydraulic turbine blades are made from stainless steels having a hard layer for the improvement of the hydro abrasive wear, corrosion resistance, and resistance to mechanical impacts in order to increase the reliability of the turbine. The thin films from stellite and tungsten carbide were obtained by the method: electrospark deposition because it has relatively low costs, are easy to obtain, the layers have a good adherence to support and the thickness can be variable in function of the established conditions. In this paper, the physical, chemical and mechanical properties of the samples will be determined using Scanning Electron Microscope (SEM), in order to emphasize the structure film-substrate and repartition of the deposition elements on the surface and in transversal section. Also, the samples were nondestructively tested using the electromagnetic sensor with metamaterials in order to establish the adherence of the thin films to the steel, proving the potential of this NDT techniques. The complex signal delivered by the sensor has been stored while scanning a 6x6 mm area. The processing algorithm involve the use of the bidimensional Fourier transform after filtering the initial signal using Walsh-Hadamard numerical filter.

Wind turbine blades (WTB) are one of the most damageable components of a wind turbine system and due to their importance must be tested during the fabrication and before installing. WTB are produced from composite materials with polymeric matrices, most of the stages of producing are manufacturing and can result in different types of defects. Therefore, non-destructive testing (NDT) techniques that provide surface and internal information of the blade are required. In this paper, ultrasonic testing using noncontact transducers for the control of composites type Glass Fiber Reinforced Plastics (GFRP) with orthophthalic polyester resins matrix is presented in order to prove its capabilities for such applications. The mechanical properties determined by above mentioned method are confirmed by destructive tests using Dynamic Mechanical Analysis.

This paper presents two methods for electromagnetic nondestructive evaluation (eNDE) of composite materials reinforced with carbon woven fibers using a sensor with orthogonal coils and a sensor with metamaterials lens. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite-difference time-domain (FDTD) software, showing a very good concordance with eNDE tests.

In this paper there are presented a series of methods and algorithms for signal processing (A-scan) and image processing (B-scan) which allow an easier and more accurate interpretation of the inspection results. The methods and the algorithms were tested for detection of a buried pipe, made of glass fiber polyester composite with a diameter of 1.3m, first when the survey conditions allowed only the scanning along the pipe, the most disadvantageous situation, but it has imposed by the configuration of the examined zone. After a few days of construction works, the site was prepared for inspection, orthogonally on the first scan direction.

Zinc oxide nanostructured materials, such as films and nanoparticles, could provide a suitable platform for development of high performance biosensing material due to their unique fundamental material properties. This paper presents the characterization of ZnO thin film as biosensing material by metallic strip grating structure (MSG), for the real-time detection. In this work, high quality ZnO films were grown on ITO/glass substrates by vacuum thermal evaporation method. We characterized by X-ray diffraction (XRD) the film crystalline quality and by scanning electron microscopy (SEM) the film morphology.

Here, we report on the Co-doping of ZnO thin films and on its role on detection of methane. The complementary investigations have been conducted in order to understand, explain and confirm the influence of the Co on the surface morphology and on the gas sensitivity exhibit at relatively low gas concentrations. The X-ray diffraction patterns indicate that the studied films present a single-phase wurtzite structure of ZnO and the X-ray Photoelectron Spectroscopy investigation confirms the successful incorporation of Co 2+ ions into the ZnO lattice. The plane-view Scanning Electron Microscopy images reveal the increase of surface to volume ratio with the increase of the dopant concentration. We investigated, the sensitivity of the sensor-devices tailored using the Co-doped and undoped ZnO thin films respectively. The maximum sensitivity, to 600 ppm methane, was obtained at an operating temperature of 170 °C. After repeated sensing measurements, the obtained results show long-term sensors stability.

The paper investigates the formation of evanescent waves in metallic strip gratings on the Ag/ZnO/SiO 2 /Si structure with silver strips when TEz incident wave in the radiofrequency range was used. The Ag/ZnO/SiO 2 /Si structure was fabricated by vacuum thermal evaporation technique and Scanning Electron Microscopy was used to evidenceits high quality structure with parallel silver strips of same width and thickness. Simulation of the evanescent wave formation at the edge of Ag strips, with thicknesses in the range of micrometers, was performed, before performing the test in the subwavelength regime by the mean of a new transducer improved with metamaterials lens. The generation in slits, in air, of the electric evanescent mode, when metallic strip grating was excited with a TEz polarized wave at a frequency of 474 MHz, was successfully demonstrated.

Metallic zinc thin films were deposited onto glass substrates using vacuum thermal evaporation method. By thermal oxidation of as-deposited Zn films, in ambient conditions, at different temperatures (570, 670 and 770 K, respectively, for 1 h) zinc oxide thin films were obtained. The structural characteristics of the obtained films were investigated by X-ray diffraction technique and atomic force microscopy. Characteristic XRD patterns of oxidized films show small and narrow peaks superimposed on the large broad background of the amorphous component of the substrate. Optical transmittance spectra were recorded and it was observed that the transmittances of the studied films increased with increasing oxidation temperature. The values of the optical bandgap, E g, evaluated from Tauc plots, were found to be ranged between 3·22 and 3·27 eV. Electrical conductivity measurements were performed and it was observed that, after performing a heat treatment, the electrical conductivity of analysed samples decreased with one or two orders of magnitude. The gas sensitivity was investigated for some reducing gases such as acetone, methane and liquefied petroleum gas and it was observed that the films studied were selective to acetone.

The most important part of wind turbine is the blade that must be tested during fabrication and functioning when can be damaged by moisture absorption, fatigue, wind guests or lightning strikes. The fibers can also appear and develop under moderated loads or cracks and delaminating due to the low energy impacts etc. The aim of this paper is to identify the modal behavior of small wind turbine blade in terms of the signal convergence, modal evolutions and frequency spectra. There are numerous methods for monitoring and detecting structural damage of the wind blades, but in this study it was used the impact hammer method. The results emphasized the natural frequencies, the modal shape of structure and the signal coherence captured in different points.

Biodegradable materials are used as alternative implants for orthopedic applications due suitable strength, fatigue resistance, ductility and biocorrosion resistance which are features for biodegradable implants. Mechanical properties can be improved by adding alloying elements. Mg alloys have been designed to meet the requirements of bone repair implant materials by adding Calcium and Yttrium. Usually Ca is added to control corrosion rate of Mg alloys and thinning grain boundaries. The system is defined as Mg-0.5Ca-xY (x=0.5, 1, 1.5), varying the Y concentration in order to slow the degradation process. Beside morphological characterization with SEM, EDX, noninvasive testing is required to be carried out the determination of mechanical characteristics. The paper presents the influence of Yttrium over elastic properties of these alloys in order to choose the best values appropriate with human bones, using Resonant Ultrasound Spectroscopy and ultrasound method.

Ni doped ZnO films were obtained by spin coating, using zinc acetate and nickel acetate as starting materials and N,N-dimethylformamide as solvent. The X-ray diffraction (XRD) analysis indicates that, spin coated films posses a polycrystalline structure. Ni doped ZnO films are single phase and no trace of nickel metal or binary zinc nickel phases are observed. The values of some structural parameters (crystallite size, surface roughness) are varying with the variation of Ni concentration. The sensitivity of Ni:ZnO films, at three different gasses (ammonia, liquefied petroleum gas and ethanol) was investigated. Obtained results indicate that our films are most sensitive to ammonia, the operating temperature was found to be 190 °C and the response time is 35 s. The gas sensitivity was found to depend on the Ni concentration in ZnO films.

Protecting coatings as thermal barrier coating (TBC) are used for yield improvement of equipment working at high temperature. Zirconia doped with yttria ceramics are considered a good TBC material due of its low thermal conductivity, refractory, chemical inertness and compatible thermal expansion coefficient with metallic support. The paper proposes the use of an electromagnetic method for evaluation of coatings on stainless steel using a sensor with metamaterial lens and comparison of the results with those obtained by complementary methods.

In this paper, we report some comparative results on the structural, electrical, and gas sensing properties of undoped, In-doped ZnO, and ZnO–In2O3 thin films, respectively. The oxide films were obtained by thermal oxidation (flash oxidation) of metallic films, deposited by thermal evaporation under vacuum. X-ray diffraction patterns reveal that oxidized films are polycrystalline, the crystallites being preferentially oriented with (002) planes parallel with the substrate. It was observed that the films’ morphology, investigated by atomic force microscopy and scanning electron microscopy, is influenced by the In amount. The temperature dependence of electrical conductivity was studied and obtained results indicate that In-doped ZnO and ZnO–In2O3 films exhibit an enhancement of electrical conductivity with four orders of magnitude by comparison with undoped ZnO film. Gas sensitivity measurements were performed for four different gases (ammonia, methane, acetone, and ethanol), and it was observed that all investigated films are more sensitive to ammonia. Also, it was observed that gas sensitivity is visibly increased for In-doped ZnO and ZnO–In2O3 samples by comparison with undoped ZnO film.

Zinc metallic films, deposited onto different substrates, were submitted to a thermal oxidation process, in air, in order to obtain ZnO thin films. X-ray diffraction patterns revealed that as-obtained ZnO thin films were polycrystalline and have a wurtzite (hexagonal) structure. The temperature dependences of the electrical conductivity during some heating/cooling cycles were studied and the conduction mechanism was interpreted in terms of Seto model. The sensitivity of ZnO thin films, at five gases, was investigated and it was established that ethanol is the test gas that produces the most significant changes in the electrical resistance of all the studied films. Some correlations between the oxidation temperature and the substrate nature and the parameters which characterize the structural and electrical properties of ZnO thin films have been established.

Polycrystalline ZnO–In 2 O 3 thin films were prepared by thermal oxidation in air of metallic Zn–In films deposited onto glass substrates by thermal evaporation under vacuum. Different oxidation conditions (oxidation temperature, oxidation time, heating rate) were used in order to prepare homogeneous films that can be used as gas sensors. Polycrystalline structure of the as-obtained films was confirmed by X-ray and electron diffraction investigations. The electrical conductivity of various thin film samples ranged between 0.84 and 6.44 (Ω cm) − 1 . Gas sensitivity to six different gasses (ammonia, methane, LPG, acetone, ethanol and formaldehyde) was evaluated and it was found that the highest sensitivity was obtained for ammonia.

This paper presents a model for evaluation of effective thermal conductivity for the composites with carbon nanotubes (CNT) having log-normal function of distribution of CNT, with direct effect over depolarization factor. The CNT are considered having cylindrical shape with L/d ratio very high. The model parameters are calculated in function of the data from literature. The influence of volume fraction of reinforced materials, of the aspect ratio of the particles included and of the ratio of the two thermal conductivities is presented.

TiO 2 thin films were prepared by DC reactive magnetron sputtering on heated Si, quartz and glass substrates using O 2 and water vapor as reactive gases. The percentage of anatase and rutile as well as the grain size strongly depend on the deposition conditions, as revealed by X-ray diffraction patterns. The films deposited on Si substrates are pure rutile, while a mixed anatase/rutile structure occurs in the films deposited on glass and quartz substrates. Smaller grain rutile and anatase films were prepared in a water vapor atmosphere, in contrast to the films grown in oxygen. The former choice considerably increases the sensing properties of titanium dioxide films. The gas sensitivity was investigated for some reducing gases (methane, acetone, ethanol and liquefied petroleum gas) and the optimum operating temperatures were found.

A wet non-conventional method for preparing aluminophosphate glasses is presented. Aluminophosphate glasses belonging to the oxide system Li2O-BaO-Al2O3-La2O3-P2O5, doped with rare-earth ions (Pr3+, Er3+, Gd3+, and Yb3+) were obtained. The influence of the doping ions on the optical properties of the phosphate glasses has been investigated in relation with micro-structural and local electronic phenomena The optical behavior of Li2O-BaO-Al2O3-La2O3-P2O5 glasses doped with 3% mol. rare-earth ions has been studied by ultra-violet-visible-near-infra-red (UV-VISNIR) spectroscopy. The transmission spectra revealed electronic transitions between 4f and 6s inner orbital of the rare-earth ions. Structural information via optical phonons was provided by infra-red (IR) absorption spectra in the range 400-4000 cm-1. IR optical phonons are characteristic for the vitreous phosphate network, showing out the glass network-forming role of P2O5. The absorption spectra present the main PO2 and P-O-P symmetrical stretch modes besides P-O-P bend mode, P-OH, P=O, PO3 2-, asymmetrical and symmetrical vibration modes. Fluorescence spectra of the rareearth- doped aluminophosphate glasses, in the visible range, were obtained by laser excitation at 514.5 nm. The fluorescence signals revealed specific electronic transitions, which provide visible and near-infra-red emission. Glasses containing rare-earth ions exhibit luminescence at the following wavelengths: Pr3+ ions at 820 nm and 880 nm, Er3+ ions at 520 nm, 550 nm and 560 nm, Gd3+ ions at 530 nm, 540 nm, 550 nm 820 and 880 nm, Yb3+ions at 530 nm, 540 nm, 550 nm and 980 nm.

The paper deals with optical and electronic properties of the aluminophosphate glasses containing Fe–Mn and Fe–Cr ion pairs in different concentration. The influence of the mixed alkali ions over the electronic properties has been investigated. The optical behavior (optical transmission) of the glass samples has been studied by UV-VIS spectroscopy and the refractive index dependency on wavelength has been discussed. The transmission spectra show features specific for the doping transition ions (TM), revealing different oxidation states of iron (Fe2+/Fe3+), manganese (Mn2+/Mn3+) and chromium (Cr3+/Cr6+) in the vitreous network. Mossbauer spectroscopy offers information regarding the TM oxidation states, redox processes and the iron coordination symmetry in the vitreous network. In the case of Fe–Mn doped glasses, the percentage of Fe2+ is about 40% and a doubled iron content leads to an increasing of Fe2+ percentage up to 53%. The replacing of lithium ions by natrium ions (mixed alkali effect) provides an increasing of the Fe2+ percentage up to 56%. The occurrence of the tetrahedral or octahedral symmetry of Fe2+ ions bonded by O2− ions depends on the transition ion nature and Li+/Na+ ratio. Infrared absorption spectra of the pair transition ions-doped aluminophosphate glasses reveal optical phonons specific for the phosphate glass matrix.

International audience; The current stage of non-destructive evaluation techniques imposes the development of new electromagnetic methods that are based on high spatial resolution and increased sensitivity. Printed circuit boards, integrated circuit boards, composite materials with polymeric matrix containing conductive fibers, as well as some types of biosensors are devices of interest in using such evaluation methods. In order to achieve high performance, the work frequencies must be either radiofrequencies or microwaves. At these frequencies, at the dielectric/conductor interface, plasmon polaritons can appear, propagating between conductive regions as evanescent waves. Detection of these waves, containing required information, can be done using sensors with metamaterial lenses. We propose in this paper the enhancement of the spatial resolution using electromagnetic methods, which can be accomplished in this case using evanescent waves that appear in the current study in slits of materials such as the spaces between carbon fibers in Carbon Fibers Reinforced Plastics or in materials of interest in the nondestructive evaluation field with industrial applications, where microscopic cracks are present. We propose herein a unique design of the metamaterials for use in nondestructive evaluation based on Conical Swiss Rolls configurations, which assure the robust concentration/focusing of the incident electromagnetic waves (practically impossible to be focused using classical materials), as well as the robust manipulation of evanescent waves. Applying this testing method, spatial resolution of approximately λ/2000 can be achieved. This testing method can be successfully applied in a variety of applications of paramount importance such as defect/damage detection in materials used in a variety of industrial applications, such as automotive and aviation technologies. © 2015.

International audience; This paper presents a possibility to enhance the spatial resolution of eNDE methods that operate in radiofrequency and high frequency range using a sensor with metamaterial lens that can manipulate the evanescent waves that appear in the space between strips and respective, carbon fibers. Also, interruptions, short-cuts of MSG as well as nonalignment of carbon fibers, lack of resin or voids, and delaminations induced by impacts with low energy can be detected and emphasized. © 2016 Taylor and Francis Group, London.

Aluminophosphate glasses belonging to the oxide system Li 2 O–BaO–Al 2 O 3 –La 2 O 3 –P 2 O 5, un-doped and doped with rare-earth metal ions (Ce 4+ , Nd 3+ , Sm 3+ ) were obtained by a wet non-conventional method. The influence of the doping ions on the optical properties of the phosphate glasses has been investigated in relation with structural features of the vitreous matrix. The optical behavior has been studied by ultra-violet–visible–near-infra-red (UV–VIS–NIR) spectroscopy, revealing electronic transitions specific for rare-earth ions. Structural information via optical phonons was provided by infrared (IR) absorption spectra in the range 400–4000 cm −1 . Raman and fluorescence spectroscopy measurements have been performed. A strong fluorescence was observed in the visible spectrum, using 514.5 nm and 633 nm laser excitation.

The sensitivity to some reducing gases (acetone, ethanol, methane and liquefied petroleum gas—LPG) of calcia doped nickel ferrite (NiFe 2 O 4 + 1%CaO) and cobalt and manganese doped nickel ferrite, Ni 0.99 Co 0.01 Mn x Fe 2− x O 4− δ ( x = 0.01 and 0.02), was investigated. Starting from nitrates, as raw materials, the samples were prepared by selfcombustion method. The nanosized powders were obtained by quick combustion. After a 30 min heat treatment at 1273 K of the compacted powder in a disk shape, some investigations of the ferrite disks were carried out by X-ray diffraction, scanning electron microscopy and measurements of the electrical resistivity sensitivity to the four test gases. The response time was studied, too. The gas sensitivity largely depends on the composition, temperature and the test gas species. The ferrite compounds doped with Co and Mn are selective to detect reducing gases at low operating temperature. The mixed ferrite with Ni 0.99 Co 0.01 Mn 0.02 Fe 1.98 O 4− δ composition is sensitive and selective to acetone gas.

The sensitivity to some reducing gases (acetone, ethanol, methane and liquefied petroleum gas-LPG) of doped nickel ferrite, Ni0.99Co0.01 MnxFe2−xO4−δ (x = 0.01 and 0.02), was investigated. Starting from nitrates, as raw materials, the samples were prepared by selfcombustion method. The investigations of the samples were carried out by X-ray diffraction, scanning electron microscopy and gas sensitivity measurements of the electrical resistivity. The gas sensitivity largely depends on the composition, temperature and the test gas species. Especially, the mixed ferrite with Ni0.99Co0.01 Mn0.02Fe1.98O4−δ composition is sensitive and selective for the detection of acetone gas.

The aim of this study is testing different new types of parchment materials during thermo-oxidative ageing at 70°C temperature, as well as under UV radiation at 50°C. The changes have been monitored by the physical–chemical tests, UV–VIS and FT–IR spectra, color and thermal analysis.Based on these experiments the corresponding types of parchment have been selected in order to assure appropriate protection of patrimony materials.

New elastomers with high content of 3,4 isoprene units have been developed during the last decades in an attempt to ensure superior performances of the final products and the present study is devoted to the investigation of some peculiarities of their ageing behaviour. On thermo-oxidative degradation, 3,4 isoprene units are less affected in comparison to cis -1, 4 and trans -1, 4 isoprene units. The degradation process consists mainly in splitting of the main chains at temperatures of 80–100 °C while at higher temperatures (120–130 °C) branching becomes a significant modification and this reaction is enhanced for the polymers containing preponderantly 3,4 units. Such behaviour leads to the fact that the processability of polymers containing high amounts of 1,2 and 1,3 isoprene units is less affected by thermo-oxidative degradation in comparison with cis -1, 4-polyisoprene, which could be explained by the fact that large amounts of double bonds are not present in the backbone of macromolecules but in the pendent groups.

The most common defects in turbine blades may be faulty microscopic and mesoscopic appeared in matrix, no detected by classical nondestructive testing (i.e. using phased array sensors), broken fibers can also appear and develop under moderated loads, or cracks and delaminations due to low energy impacts, etc. The paper propose to present the results obtained from testing of glass fiber reinforced plastic used in the construction of the wind turbine blades as well as the monitoring of the entire scalable blade using wireless sensors placed on critical location on blade. In order to monitories the strain/stress during the tests, the determination of the location and the nature of defects have been simulated using FEM.

Carbon Fiber Reinforced Plastics are used in most wide domains due their low density, lack of mechanical fatigue phenomena and high strength–to weight ratio. From electromagnetic point of view, Carbon Fiber Reinforced Plastics structure represents an inhomogeneous structure of electric conductive fibers embedded into a dielectric material, thus an electromagnetic configurable architecture can be used to evaluate above mentioned defects. The paper proposes a special sensor, send receiver type and the obtaining of electromagnetic image by post-processing each coil signals in each point of scanning, using a sub-encoding image reconstruction algorithm and super-resolution procedures. The layout of fibers can be detected interrogating only diagonal reception coils.

The most important part of wind turbine is the blade that must be tested during the fabrication and during the functioning when can be damaged by moisture absorption, fatigue, wind gusts or lightning strikes. The novelty of the paper is represented by the employing of wireless sensors embedded in a scalable wind turbine blade made from Glass Fiber Reinforced Plastics together with Fiber Bragg Gratings in order to effectuate structural health monitoring in static conditions. The sensors are placed on critical location on blade determined by FEM simulation and a comparison between the complementary methods is done.

Zinc oxide nanostructured materials, such as films and nanoparticles, could provide a suitable platform for development of high performance biosensing material due to their unique fundamental material properties. In this study, the enzyme biosensing consisting of a zinc oxide (ZnO) nanoparticles were grown on SiO2/Si substrates by vacuum thermal evaporation method and their sensing characteristics are examined in air and investigated. The film morphology is characterized by X-ray diffraction (XRD) the film crystalline quality and by scanning electron microscopy (SEM). Also, the interest in surface waves appeared due to evanescent waves in the metallic strip grating structure (MSG-Ag/ZnO/SiO2/Si) in sub-wavelength regime. Before testing the sensor with metamaterials (MMs) lens in the sub-wavelength regime, a simulation of the evanescent wave's formation has been performed at the edge of Ag strips, with thicknesses in the range of micrometers.

This paper presents two methods, non-contact low frequency ultrasound method and fiber Bragg gratings, and their application to nondestructive testing of glass fiber reinforced composites used in wind turbine blades. Theoretical models are used and experimental results are in good concordance with destructive testing results.

In this paper, we investigate the cholesterol sensors consisting of a mixture of cholesterol oxidase (ChOx) and zinc oxide (ZnO) nanoparticles were grown on ITO/glass substrates by vacuum thermal evaporation method and their sensing characteristics are examined in air. Also, the interest in surface waves appeared due to evanescent waves in the metallic strip grating in sub-wavelength regime. Before testing the transducer with metamaterials lens in the sub-wavelength regime, a simulation of the evanescent wave's formation has been performed at the edge of Ag strips, with thicknesses in the range of micrometers.

The control of wind turbine's components is very rigorous, while the tower and gearbox have more possibility for revision and repairing, the rotor blades, once they are deteriorated, the defects can rapidly propagate, producing failure, and the damages can affect large regions around the wind turbine. This paper presents the test results, performed on glass fiber reinforced plastics (GFRP) suitable to construction of wind turbine blades (WTB). The Young modulus, shear modulus, Poisson's ratio, ultimate stress have been determined using tensile and shear tests. Using Dynamical Mechanical Analysis (DMA), the activation energy for transitions that appear in polyester matrix as well as the complex elastic modulus can be determined, function of temperature.

The experimental research involved in this paper consists in the obtaining of superior physical, chemical and mechanical properties of stainless steels used in the construction of hydraulic turbine blades. These properties are obtained by deposition of hard thin films in order to improve the wear resistance, increasing the hardness but maintaining the tenacious core of the material. The chosen methods for deposition are electrospark deposition because it has relatively low costs, are easy to obtain, the layers have a good adherence to support and the thickness can be variable in function of the established conditions and the pulsed laser deposition because high quality films can be obtained at nanometric precision. The samples will be prepared for the analysis of the structure using optical method as well as for the obtaining of the optimal roughness for the deposition. The physical, chemical and mechanical properties will be determined after deposition using SEM and EDX, in order to emphasize the structure film-substrate and repartition of the deposition elements on the surface and in transversal section. The non-destructive testing has emphasized the good adherence between deposited layer and the metallic support, due to double deposition, spallation regions doesn't appear.

CFRP have applications among most different domains due their low density, high elastic modulus and high ultimate strength along the carbon fibers direction, no fatigue and the expansion coefficient is small. This paper presents the behavior of carbon fiber woven-PPS composites at low velocity impacts. The transversal electrical conductivity is modified due to the plastic deformation following the impacts, and thus electromagnetic procedures can be used for assessment of CFRP using a high resolution sensor with metamaterials lens and comparing the results with those obtained from ultrasound testing with phased array sensor. The area of the delamination is overestimated when the method of phased array ultrasound is used and substantially underestimated by the electromagnetic testing. There were a good agreement between the simulations with finite element method and experimental measurements.

WOS: 000290006900028 Undoped and Pd-doped titanium oxide thin films (0.5 wt.%) were prepared by the sol-gel technique (dip-coating) on glass and silicon substrates. The as-deposited thin films were compacted by subjecting them to different annealing temperatures (300 degrees C, 500 degrees C). The dependences of the electrical conductivity vs. inverse temperature were investigated in air and in vacuum. A study of the effects of Pd-doping, annealing temperature and ambient conditions on their electrical properties was performed. The sensing behavior of titanium oxide thin films exposed to some reducing gases (methane, acetone, ethanol, formaldehyde and liquefied petroleum gas) was carried out, by means of electrical conductivity measurements. All the studied films are most sensitive to formaldehyde, with a special remark for the Pd-doped ones deposited on silicon substrates. (C) 2011 Elsevier B.V. All rights reserved. CNCSISConsiliul National al Cercetarii Stiintifice din Invatamantul Superior (CNCSIS) [PCCE-ID_76] The financial support from the CNCSIS Contract PCCE-ID_76 is acknowledged by D. Mardare.

Cobalt–nickel oxide films of known stoichiometry (x = Ni / (Co + Ni) = 0.30–0.63) were deposited on glass slides by using a spin-coating method and were UV irradiated for 2 h. The structure and morphology of thin films evidenced nanocrystalline spinel structures. Thin films with x = 0.63–0.5 have a mixed phase structure and good sensing properties for ethanol. Thin films with x = 0.30–0.40 have a single spinel phase, are ferrimagnetic and highly conductive at 300 K and have magnetoresistance ratios of 5–8%. Four-probe measurements indicate an insulator–metal transition at temperatures slightly below ferromagnetic Curie temperature. Metallic Ni and Co particles improve thin film functional properties.

ZnO thin films were grown on different substrates (glass, quartz, silicon wafers, etc) by vacuum thermal evaporation. Different thermal treatments were performed in order to obtain transparent and conductive or high resistive ZnO tin films. The optical and electrical properties of ZnO thin films are dependent on the crucible temperature, annealing conditions and on the substrate nature. The thin films are transparent and have an electrical resistivity in 10−4 Ωm regio. The annealing process performed in vacuum at 573K or under UV irradiation determines a decrease in the electrical resistivity of films.

This paper presents complementary methods used in nondestructive evaluation (NDE) of composite materials reinforced with carbon woven fibers as two electromagnetic methods using sensor with orthogonal coils and sensor with metamaterials lens as well as ultrasound phased array method and Fiber Bragg gratings embedded instead of a carbon fiber for better health monitoring. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite- difference time-domain (FDTD) software, showing a very good concordance with electromagnetic nondestructive evaluation tests.

International audience; Near-infrared spectral analysis was useful to quantify the ester content of chemically modified cellulose and lignocellulosics. Two kinds of samples were studied, as long aliphatic-chain cellulose esters and wood sawdust chemically-modified either by anhydrides or by ethylene carbonate. It was possible to determine the degree of substitution (DS) of such samples through a correlation by partial least square (PLS) of second-order derivative of NIR spectra. This technique was efficient even when DS values were low, which is difficult to do by using FTIR. It was also possible to distinguish reagent molecules that were attached to the cellulosic substrate by hydrogen bonding from those linked by covalent bonding.

We have prepared ZnO films by thermal oxidation of Zn metallic films and analyzed their structure, morphology, wettability, and gas sensing properties. Films structure and surface morphology were derived from X-ray diffraction and atomic force microscopy data. XRD analysis indicates that obtained ZnO films posses a crystalline structure. An increase of the surface roughness was observed, once the oxidation time increases. Surface wettability investigations showed that under UV-illumination, ZnO films present a reversible switching between hydrophobic and hydrophilic states. The gas response to methane, acetone, and formaldehyde was investigated, and experimental results indicate that tested films are selective to methane. Also, the gas response was found to increase, as the oxidation time of metallic films increases. This behavior was attributed to the structural changes (crystallite sizes, surface roughness), which take place during oxidation process.