Different Thicknesses Of Sample Research Articles

A Study on Simultaneous Measurement of Partial Discharge in Epoxy Resin Insulator using IMC and Rogowski Coil

In practice, field measurement of partial discharge is easily suffered by interferences due to the noisy signal has been mixed with the resulting partial discharge signal. Therefore, the detection and measurement of PD are important to monitor the insulation life in high voltage (HV) power equipment. The paper presents the simultaneous measurement of partial discharge (PD) pulse parameters using the impedance matching circuit and the Rogowski coil sensor to study the features of partial discharge on the epoxy resin insulator. Two different thicknesses of samples were used to observe the PD pulse parameters with the voltage applied vary depending on the thickness of the sample to attain constant electric field intensity for both samples. The step response parameters resulted from the measurement can be used as a time domain features to discriminate various types of PD in HV power equipment. Thus, the PD can be observed clearly, maintenance can be performed, and the performance of the power system can be improved.

The sound absorption of air permeable structures produced by 3D printing using PLA material

The aim of the contribution is comparison of noise absorption properties of two designs of acoustic dampening air permeable structures. A circular test samples with a diameter of 89 mm and three different thicknesses of samples were produced using of 3D printing process. In addition to the thickness, the internal structure of the samples was also changed. The prepared samples were tested using an impedance tube. The acoustic properties of the test samples were investigated in accordance with the standards ASTM E1050-19, E2611-17 and ISO 10534-2. A two-microphone method based on the calculation of transfer function method was used to determine the absorption coefficient of the designed structures. The Brüel&Kjær PULSE system was used to estimate the frequency dependence of sound absorption coefficient of test samples. In the paper are presented the experimentally obtained values of the sound absorption coefficient for different structure design and thicknesses of samples produced by 3D printing technology. The measurements were evaluated in the range of working frequencies of the impedance tube.

Thermal and microwave-absorbing properties of doped polyaniline–epoxy nanocomposites for stealth applications

The thermal properties of polymeric nanocomposites can be examined using TGA and DSC techniques, while dielectric properties can be examined through simulated scattering (S11, S12, S21, and S22) parameters. Polyaniline (PAni) nanopowder was synthesized using chemical oxidative polymerization techniques. Consequently, the crystallite size and morphology of the synthesized powder were examined using the XRD, TEM, and FESEM techniques. Further, a series of polymeric nanocomposites was developed via wet mixing and compressor molding techniques for various volume percentages (54.0, 57.5, 60.1, and 61.7 vol%) of synthesized powder within PAni/epoxy composites. Consequently, dielectric and absorbing properties have been measured using a vector network analyzer and its software module. The computed complex permittivity data were used to evaluate the absorption for different thicknesses of samples. A minimum reflection loss of − 22.3 dB (> 99.9% absorption) was optimized with broadband frequency ranges. The unique heterostructures of nanocomposite are responsible for the enhanced absorption and shielding performance.Graphical abstract

Carbon Fiber Resin Composite Strength Relative to Orientation

Carbon fiber resin polymer (CFRP) is a laminate of multiple sheets of carbon fiber woven cloth infused with epoxy resin. The combination is hard, strong, and lightweight, making it ideal for aerospace applications. CFRP is not as well characterized as other construction materials such as metal, wood, and plastic, for which datasheets are easy to find in the public domain. To promote the wider use of CFRP, we used a universal testing machine to measure CFRP sample coupons obtained from manufacturers of experimental aerospace vehicles. The tensile strength and elongation of the CFRP coupons were measured with the weave oriented at an angle of 0, 45, and 90 degrees. Results show that CFRP sheets with a weave orientation of 45 degrees is 1.5 times stronger than the weave of 0 degrees, and 1.1 times stronger than the weave of 90 degrees. These results imply that the strongest part of CFRP sheets is diagonal relative to the weave. For future work, we propose to use larger sample sizes, incorporate different thicknesses of sample, and compare CFRP samples to metal samples of similar sizes.

Electrospun SiO<sub>2</sub> Nanotextiles for Preservation of a Tangible Cultural Heritage

The developing nanotechnology is getting infiltrated into a wide area of industries. A variety of nanotextiles can be produced from different materials (e.g. polymers, SiO2). Their applications are possible in many industrial branches as well as civil engineering. Silica-based nanotextiles can play a fundamental role in civil engineering. The potential utilization of nanotextiles in civil engineering is promising as surface protective layers. Wettability of SiO2 nanotextiles was studied on different thicknesses of samples and were tested under static conditions by determination of the water contact angle. Their water contact angle, which indicates the degree of wetting, was measured using an optical tensiometer.

Changes in the growth orientation, morphological and optical properties of sol-gel nanocrystalline ZnO thin films coated with different thickness

ABSTRACTNanocrystalline ZnO thin films with the varied thickness were deposited on glass substrate using sol-gel spin coating method, and the different thickness of samples was achieved via changing the number of layers. X-ray diffraction patterns of samples showed the preferential orientation at (002) planeupon coating with 2 layers and the gradual increase in random orientation with coating up to 6 layers. Scanning electron microscopeimages appeared a few layer interfaces for 4 and 6 layers sample, and atomic force microscope images revealed the larger particle size and rougher surfacewith increasing thickness, which showed the obvious effects on optical properties of samples too. The increased absorption and reduced energy gap were found through deducing transmittance curves of samples. Further, photoluminescence characteristic was measured and revealed that there are the best intrinsic emission in ultraviolet region and lowest defect emissions in visible region for the sample coated with 4 layers.

A non-destructive optical experimental method to predict extinction coefficient of glass fibre-reinforced thermoplastic composites

The aim of this paper is to develop a cost-effective, efficient and fast experimental optical method to predict the optical properties (extinction coefficient) of semi-transparent glass-fibre-reinforced polymer composites. The extinction coefficient takes into account the effects due to the absorption and the scattering phenomena in a semi-transparent component during the laser processes, i.e. TTLW (Through-Transmission Laser Welding). A laser as light source and a reflex camera equipped with a macro lens as a measuring device are used in the present method. It is based on the measuring of the transmission of light through different thicknesses of samples. The interaction between the incident laser beam and the semi-transparent composite is examined. The results are presented for the case of a semi-transparent composite reinforced with unidirectional glass fibre. A numerical method, ray tracing, is used to validate the experimental results. The ray tracing method is suitable for characterizing the light-scattering in semi-transparent materials.

Variations in Crystalline Structures and Electrical Properties of Single Crystalline Boron Nitride Nanosheets.

We report the studies of (1) the basic mechanism underlying the formation of defect-free, single crystalline boron nitride nanosheets (BNNSs) synthesized using pulsed laser plasma deposition (PLPD) technique, (2) the variation in the crystalline structure at the edges of the hexagonal boron nitride (h-BN) nanosheets, and (3) the basic electrical properties related to the BNNSs tunneling effect and electrical breakdown voltage. The nanoscale morphologies of BNNSs are characterized using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). The results show that each sample consisted of a number of transparent BNNSs that partially overlapped one another. Varying the deposition duration yielded different thicknesses of sample but did not affect the morphology, structure, and thickness of individual BNNSs pieces. Analysis of the SEM and HRTEM data revealed changes in the spatial period of the B3–N3 hexagonal structures and the interlayer distance at the edge of the BNNSs, which occurred due to the limited number of atomic layers and was confirmed further by x-ray diffraction (XRD) study. The experimental results clearly indicate that the values of the electrical conductivities of the super-thin BNNSs and the effect of temperature relied strongly on the direction of observation.

Features of the temperature dependence of pressure of solid helium at low temperatures

A series of experiments has been performed to investigate the conditions of formation of a disordered (glass-like) state in crystals of 3He. With the help of precise measurements of pressure at constant volume it has been established that a glass phase is formed easily in rapidly cooled crystals grown under homogeneous temperature conditions in the presence of large numbers of nucleation centers. This phase can be removed only by careful annealing. This result has been found in both 3He and 4He, and is independent of type of quantum statistics and determined mainly by crystal growth conditions. An analysis of similar measurements has been performed using a different cell where during the crystal growth a directed temperature gradient was created. In this case, additional defects created as a result of deformation of the crystal were necessary to form a glass-like phase. The degree of deformation of a crystal, achievable in the experiment, was sufficient to form a glass-like phase in solid 4He, but not in a crystal of 3He where the atoms have a large amplitude of zero-point oscillations. Analyzing a temperature dependence of pressure, a study of the features of a phonon contribution to the pressure was also carried out. It was found that in both crystals 3He and 4He at different thicknesses of samples the phonon pressure differs by several times. This effect is qualitatively explained by that that in thin samples an interaction among layers of atoms becomes stronger. This leads to decreasing the phonon contribution to the thermodynamic properties of the helium crystal at low temperatures.

Effects on measurement of photon-atom scattering of applied pressures on sample at different thickness

N coh / N Comp and NK β / NK α intensity ratios of scattered photons by Zn in the linear region and the infinite mass thickness region are measured as functions of the pressure used for compressing the pellets with a Si(Li) detector using Am-241 and Fe-55 annular source. Besides, the effect on the experimental intensity ratio of relation between two different thicknesses of sample with applied different pressures on the sample is investigated in this study. Harmony between the linear and infinitive (critical) thickness region and the applied pressure on the sample has directly affected the experimental intensity ratios. Experimental results were not compared with various theoretical values in the literature, for present results constitute the first experimental measurements.

Photoacoustic Spectra in Ternary Semiconducting Compound CdIn2S4

The amplitude and phase of the photoacoustic (PA) signal have been studied in ternary semiconducting compound CdIn2S4. By measurements of the phase difference of variable chopping frequency of the incident light on different thickness of samples, thermal conductivity and thermal diffusivity were given to be 1.3×10-2 cal/g·sec·K and 2.3×10-2/sec, respectively. The treatment of sample surface has been also studied: the PA amplitude shows gentle slope with a rough surface layer. The phase difference of the PA signal agreed well with a two-layer model by extending the Rosencwaig and Gersho theory.