Multispectral impedance quality testing of coil-coating system using principal component analysis

The task of quality checking of the coil-coated system was undertaken using impedance spectroscopy. In order to properly characterize the system the new impedance spectrum was calculated as an averaged result of 12 experimental spectra obtained from 12 different places of the sample at the same time of immersion in 3% of NaCl. The experimental spectra were recorded for a 24-h period at 1 h intervals between starting points of each measurement. Averaged impedance at each frequency point of the calculated spectrum was characterized by standard deviation. Impedance analysis using two-time constant equivalent electrical circuit was conducted showing the permissible parameter scatter for the checked system. A new classification method of obtained parameters using principal component analysis was presented. This approach enables to identify samples of low quality.     

Damage detection of composite milling process by recurrence plots and quantifications analysis

We study the dynamics of a milling process of carbon fiber reinforced plastic based on experimental time series of cutting force with help of recurrence plots and recurrence quantifications methods. The two cases of composite machining are analyzed in detail. The first case is a milling of undamaged material, while the second is a milling of damaged material. The detailed recurrence analysis shows interesting results, and additionally some of all quantifications can be used to damage detection.     

Integral bread development with soybean, chia, linseed, and folic acid as a functional food for women

Six bread formulations were developed, using different proportions of whole-wheat flour, chia seeds and flaxseed flour. All of our formulations were added with folic acid. Sensorial and texture evaluations were performed, showing good acceptance of the products. Proximal chemical analysis was carried out; in addition, the following parameters were determined: calcium, phosphorus, total dietary fiber, folic acid, water hydration capacity, Glucose Dialysis Retardation Index (GDRI) and fatty acids. The results obtained showed higher protein levels in the developed breads (23.23-30.24 (g/100g dry matter) as compared to a control (21.00% of proteins in bread elaborated without chia or flaxseed). Furthermore, the breads contained 10.07-12.15 of lipids (g/100g dry matter) (linoleic acid: 2.43-4.05%; linolenic acid: 1.12-4.46 %; oleic acid: 2.93-6.13 %), GDRI values were between 89.1 and 98.1 % and folic acid was in the range 699.44 - 991.3 (microg/100g dry matter). The same parameters were determined in the chia seed and in the flaxseed flour. It was concluded that; due to their high levels of protein, insaturated fatty acids (omega-3 and omega-6), dietary fiber and folic acid, these breads have a high nutritional value, so they could have special benefits for woman.     

Study washboarding phenomenon in frame sawing machines

The paper concerns washboarding phenomenon where for every kind of sawing a very regular pattern is characterised by a sinusoidal – like variation in board thickness. That pattern is an effect of the saw blade lateral vibrations. It is palpable that these vibrations are detrimental to the cutting process, and lead to poor surface quality and dimensional accuracy, and raw material waste. For band saws in the contemporary literature models explaining a washboarding phenomenon are supported on self-excited (self-induced) vibration theories. However, these explanations cannot be simply broadened into the washboarding phenomenon in frame sawing machines. In this work based on theoretical and experimental investigation the washboard pattern formation is clarified by the authors with the use of a theoretical model, in which the rugged surface is an effect of vibrations generated by lateral cyclic loading and lagged wave formation. The authors hope that their obtained results contribute significantly to further understanding of this important but complicated phenomenon.     

ICP-MS multi-element profiles and HPLC determination of furanic compounds in commercial tequila

In this work, inductively coupled plasma mass spectrometry determination of Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Tl, V, Zn, Th and U in commercial tequila has been accomplished. The samples were tenfold diluted (1% HNO₃), ethanol (4% v/v) was added to multi-element calibration solutions and possible spectral interferences were controlled by the use of collision/reaction cell technology. The results obtained in the analysis of 40 brands showed low concentration levels of the elements, in agreement with actual Mexican regulations, except for copper. Statistically significant differences were found between the concentration levels of copper, molybdenum, mercury and thorium in 100% agave and mixed tequila brands. In search of parameters useful for discrimination between 100% and mixed tequila categories, 5-hydroxy-methylfuraldehyde, 2-furoic acid (2-FAC), 2-furaldehyde (2-FAL), 2-furylmethylketone (2-FMC), 5-methylfuraldehyde (5-MFA), syringaldehyde (SIR) were also determined, using simple and fast reversed phase chromatographic procedure. Principal component analysis was used as the variable reduction procedure. In the multivariate model obtained, a natural separation of 100%, mixed and aged tequilas has been observed in the space defined by the first three principal components that accounted for 94% of total system variability. The analysis of correlation revealed statistically significant direct relationship between 100% tequila and 2-FAL, 5-MFA, Cu (β = 0.781, p = 0.028; β = 0.688, p = 0.042; β = 0.664, p = 0.046, respectively), between mixed tequila and Hg, Th, Mo (β = 0.948, p = 0.000; β = 0.905, p = 0.002; β = 0.867, p = 0.012, respectively) and between aged tequila and SIR, 2-FAC (β = 0.937, p = 0.000; β = 0.889, p = 0.000, respectively). In conclusion, among 25 parameters initially selected, the above 8 (2-FAL, 5-MFA, Cu, Hg, Th, Mo, SIR, 2-FAC) could be useful in the multivariate discrimination between tequila categories.     

Lattice and Grain‐Boundary Diffusion of Al in Tetragonal Yttria‐Stabilized Zirconia Polycrystalline Ceramics (3Y‐TZP) Analyzed Using SIMS

Aluminum oxide was deposited on the surface of 3 mol% yttria‐stabilized tetragonal zirconia polycrystals (3Y‐TZP). The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B‐type kinetic region were investigated by secondary ion mass spectroscopy. The experimental results for the lattice diffusion (D_B) and grain boundary diffusion (D_GB) are as follows: and where δ is the grain‐boundary width and s is the segregation factor.     

Improving the Physicochemical Properties of Fe–25Cr Ferritic Steel for SOFC Interconnects via Y-Implantation and Y2O3-Deposition

The present study investigated the role of the reactive-element effect (REE) in improving the corrosion resistance, chromium vaporization rate, and electrical conductivity of the Fe–25Cr ferritic steel modified either by means of yttrium implantation or chemical deposition of yttrium oxide from metaloorganic compound vapors. The corrosion kinetics of the Fe–25Cr steel, both pure and modified, were determined under isothermal conditions in air and an Ar–H₂–H₂O gas mixture at 1,073 K. A significant improvement in corrosion resistance was observed after surface modification. XRD and SEM–EDS investigations showed that the protective Cr₂O₃ layer formed the main part of the scale. Measurements of Cr vaporization rate in the air–H₂O gas mixture revealed that both surface modifications of the steel significantly suppressed the formation of volatile chromium compounds to a large degree. The yttrium-implanted steels oxidized both in air and the Ar–H₂–H₂O mixture were characterized by the lowest area specific resistance and thereby did not exceed the acceptable ASR level (0.1 Ω cm²) for interconnect materials in the temperature range of 973–1,073 K, unlike pure steel and the steel coated with Y₂O₃.     

Optimization of impedance measurements using ‘chirp’ type perturbation signal

The paper presents a novel method of impedance measurements using the non-stationary ‘chirp’ signal. Variable sampling frequency has been employed in a process of acquisition of the voltage perturbation and current response signals. Such solution allows significant decrease in a number of data necessary to obtain an impedance spectrum as well as simplification and acceleration of the calculation process. It has been found that an accuracy of the results obtained with this method was directly proportional to the frequency resolution, with which impedance values were obtained.     

Evaluation of corrosion inhibition of brass-118 in artificial seawater by benzotriazole using Dynamic EIS

The paper presents the results of corrosion behaviour of brass-118 in artificial seawater and the inhibitor effect of benzotriazole (BTA) by using a novel method called dynamic electrochemical impedance spectroscopy (DEIS). This method allows the tracing of the dynamics of the corrosion and the inhibition process based on the evaluation of electrical parameters of the equivalent circuit. Instantaneous impedance spectra recorded up to 10 h show that an exposure of few hours is not enough for the determination of inhibition efficiency. The results indicate the usefulness of DEIS technique in the field of inhibitor research.     

Quadratic Cohen representations in spectral analysis of serration process in Al–Mg alloys

Important from mechanical point of view the Portevin–Le Chatelier serration phenomenon is being characterized by a complicated spectral profile. As a typical example of nonstationary processes it demands a special treatment allowing to follow the evolution of energy of stress fluctuations as a function of strain. The authors suggest the utilization of a compact system of quadratic transformations, known as Cohen class, as a technique enabling the reliable analysis of serration processes. In this elaboration a comparison of the application of various Cohen decompositions to analyze frequency bands has been introduced.