The fault detection of transformer windings' deformation based on Vibration frequency response analysis

Photomineralisation of 2,4‐dichlorophenol (DCP) in aqueous solutions (10.0–100.0 mg/L of C) was systematically studied at 318 ± 3 K, in an annular laboratory‐scale reactor, by photocatalytic membranes immobilizing titanium dioxide, as a function of substrate concentration, and absorbed power per unit length of membrane. Kinetics of both substrate disappearance, to yield intermediates, and total organic carbon (TOC) disappearance, to yield carbon dioxide, were followed (first series of experiments). At a fixed value of irradiance (1.50 W⋅cm−1), other series of mineralization experiments were repeated (second series of experiments) by carrying out only analyses of chemical oxygen demand (COD), in order to compare modelling results of the two sets of experiments. In both sets of experiments, stoichiometric hydrogen peroxide was used as oxygen donor. For the first series of experiments, a kinetic model was employed, already validated in previous work, from which, by a set of differential equations, four final optimised parameters, k1 and K1, k2 and K2, were calculated. By these parameters, the whole kinetic profile could be fitted adequately. The influence of irradiance on k1 and k2 could be rationalised very well by this four‐parameter kinetic model. Modelling of quantum yields, as a function of irradiance, could also be carried out satisfactorily. As has been found previously for other kinds of substrates, modelling of quantum yields for DCP mineralization is consistent with kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or intermediates leading finally to carbon dioxide, paralleled by a second competition kinetics involving superoxide radical anion. For the second series of experiments, on the contrary, the Langmuir‐Hinshelwood model was employed. Uncertainties of COD analyses, coupled with discrepancies of this model and with its inability to reproduce kinetics up to complete mineralization, are underlined.

Power utilities desire an alternate noninvasive test method for assessing the diagnostic status of power apparatus. The primary reason is to minimize the economic constraints and ensure lifetime and reliability of power apparatus within shorter duration. In this context, frequency response analysis (FRA) method is increasingly recommended. The underlying principle of fault diagnosis using FRA method focuses on correlating the insulation condition to the changes in the magnitude and phase frequency response function. Existing practices validates the usage of FRA method in ascertaining the insulation integrity of transformers. Further attempts to expand the potential of FRA in method in determining the insulation status of power apparatus other than transformers, lack scientific and experimental evidence. To fill this gap, a research on using FRA method in assessing the insulation condition of high voltage bushings and power cables is initiated. Initially, test samples of insulation materials that are commonly used in bushings and cables are selected. The chosen samples are prepared in such a way that they represent common defect conditions that inflict premature material degradation and failures. These samples are grouped accordingly, placed on test cells, subjected to nonconventional FRA tests and their diagnostic status are respectively ascertained through comparative analysis. Following this, the pertinent findings are validated on actual bushings and power cables installed on a power transformer. In summary, the findings of this studies not only validate the usage of FRA method but provides the missing scientific and technical evidences and indices that could be used for diagnosing power apparatus.

The aim of the work was to study the effect of various microelectronic structural and technological implementations to improve the field emission properties of the nano-carbon emitters. The field emission properties of vacuum diodes with nanodiamond-graphite emitters of different geometric shapes was researched. The nanodiamond-graphite layers deposition were carried out from ethanol vapor at low pressure using microwave plasma. Three series of experiments were studied. Researching of emission currents with flat cathodes on silicon wafer coated by nanodiamond-graphite layer were done in first series of experiments. In the second series of experiments, the electrical parameters of integrated field emission diodes with flat nanodiamond-graphite emitters was studied. In the third series of experiments, the electrical parameters of field emission with flat nanodiamond-graphite formed as a micro-sized needles or blades were studied. Vacuum emission studies were done at temperature 300K and pressure 1 × 10^-6 Torr. <br/> Threshold voltage from10-50V per micron and current density about 0.2 A/cm² were obtained in the first series of experiments. In the second and third series of experiments, a threshold voltage from 1 to 10V/ &mu;m and current density of 1.75 A/cm² were displayed. The greatest current density more than 20 A/cm² was obtained using a blade-type emitter.

Callus induction and later plant regeneration were studied in four widely grown garlic (Allium sativum L.) cultivars from Europe. Root segments from in vitro plantlets were used as starting material. In addition to cultivar effects, the effects of auxin and cytokinin levels and the position of the segments on the root were studied. There were no statistically significant differences among cultivars for the number of root segments that induced callus in the two series of experiments. The average induction frequency was 34.7% in the first series of experiments. Callus induction on apical root segments was significantly higher compared to callus induction on non-apical root segments in the second series of experiments. Two months after callus induction, callus lines were transferred to a regeneration medium consisting of Murashige and Skoog basal medium supplemented with 30gl−1 sucrose and 1 mgl−1 (4.6μM) kinetin. Calluses derived from different experiments were quite uniform with respect to their regeneration potential. Also it was found that our regeneration system was cultivar-independent. The average shoot regeneration frequency was 17.9% in the first series of experiments. Highly significant differences were found in the frequency of shoot regeneration among different callus induction treatments. When the cytokinin 6-(γ,γ-dimethylallylamino)purine (0.1mgl−1∶0.5 μM) was present during callus induction, shoot regeneration ranged from 30.10 to 47.60%. Shoot regeneration from callus induced on non-apical segments was higher, although not significant, compared to callus induction from apical root segments in the second series of experiments. All in all, an efficient callus induction and plant regeneration system was developed from both apical and non-apical segments taken along the entire length of the roots. This system has potential to be used for garlic transformation.

In core-disruptive accidents of sodium-cooled fast reactors, fuel discharge from the core region reduces the possibility of severe re-criticality events. In-core coolant channels with large hydraulic diameters, such as the control-rod guide tube and a concept of the Fuel Assembly with Inner Duct Structure have a potential to provide effective fuel-discharge paths if effects of sodium in these paths on molten fuel discharge are limited. Two series of experiments were conducted to investigate fuel-discharge behaviour through the sodium-filled channels. In the first series of experiments, an alloy with low melting temperature was ejected into a water channel to clarify dominant phenomena for melt discharge through the coolant-filled channel and to develop methodologies for evaluating the effects of coolant on melt discharge. In the second series of experiments, a molten alumina was discharged through the sodium-filled channel in order to verify the applicability of the knowledge and evaluation methodologies obtained in the first series of experiments to the sodium-filled channel. These series of experiments showed that the discharge path can be entirely voided by the vaporisation of a part of the coolant at the initial melt discharge phase that this is followed by coolant vapour expansion and that melt penetrates significantly into the voided channel. Preliminary extrapolation of the present results to the in-core coolant channel suggests that the effects of the sodium on fuel discharge are limited and, therefore, in-core coolant channels will provide effective fuel-discharge paths for reducing neutronic activity.

In the present study, sand and expanded polystyrene (EPS) geofoam were evaluated as potential stabilizers in improving the swelling behaviour of bentonite. A comprehensive laboratory experimental programme was conducted on bentonite with a high swelling potential. Five dosage levels of sand and five different thickness of EPS geofoam were investigated in two stages of the experiments. In the first stage of testing, the effect of sand on the swelling pressure of bentonite was investigated by two series of experiments. In the first series of experiments, bentonite at optimum water content was mixed with sand in proportions of 20, 40, 60 and 80% by weight. In the second series of experiments, the same percentages of sand were used as in the first series of experiments but the sand and bentonite were not mixed together. The sand was placed on the sample of bentonite which was then compacted at optimum water content. In the second stage of testing, the effect of EPS geofoam on the swelling pressure of bentonite was investigated using different thicknesses of EPS geofoam placed on the sample of bentonite. These thicknesses were the same as the thicknesses of sand which was placed on the sample of bentonite in the second series experiments of the first stage. These experiments show that the expansive soil can be successfully stabilized by sand and EPS geofoam.

Adult domestic pigeons, with thermodes chronically implanted in the vertebral canal, were trained to walk on a treadmill. In the first series of experiments, EMG activity in a pectoral (M. pectoralis) and a femoral muscle (M. biceps femoris) was measured to determine if shivering could occur during exercise. When the spinal cord was cooled (36.2 +/- 0.5 degrees C) during exercise (0.6 km/h), pectoral muscle EMG activity increased by 80%, while femoral muscle EMG activity did not change significantly. EMG activity remained unchanged during exercise in control experiments where the spinal cord was not cooled. In the second series of experiments, the spinal cord was first cooled (36.1 +/- 0.5 degrees C) for 5 min in resting pigeons and then the treadmill was started. Spinal cord cooling during rest significantly increased pectoral muscle EMG activity but not that of the femoral muscle. Within 1 s after the onset of exercise, EMG activity in the pectoral muscle decreased by 74%. In both series of experiments, shivering was not induced in the femoral muscle. The level of pectoral muscle EMG activity stimulated by spinal cord cooling during exercise in the first series of experiments corresponded to the level to which EMG activity was reduced by exercise during spinal cord cooling in the second series of experiments (192% and 186% in relation to the post-cooling level, respectively). It is concluded that shivering can be induced in the pectoral muscle by spinal cord cooling during exercise in the pigeon.(ABSTRACT TRUNCATED AT 250 WORDS)

The oxidation kinetics of nitrite to nitrate ions by potassium ferrate(VI) in a wide range of pH, from neutral to alkaline medium has been studied. Two series of kinetic experiments based on the different technologies for obtaining potassium ferrate(VI) were conducted. In the first series of experiments, crystalline potassium ferrate(VI) was prepared by the chemical synthesis. In the pH range 6.5–11, solid K 2 FeO 4 was added to solutions of nitrite ions at known concentration and pH. Kinetic studies were performed under pH and ionic strength controlled conditions. Half times for these experiments ranged from milliseconds to a few minutes. In the second series of experiments, solutions of K 2 FeO 4 were generated by the electrochemical synthesis. Alkaline solutions of potassium ferrate(VI) in 8.0 M KOH were obtained at t=20 o C by electrochemical dissolution of steel plates (S=10 cm 2 ) containing: C – 0.16 %; Mn – 0.43 %; Si – 0.04 %; S – 0.03 %; P – 0.04 %; the rest is Fe. The experiments were performed with fresh solutions of potassium ferrate(VI) and solutions, aged after the synthesis for several days. Kinetic studies were performed under nitrite concentrations controlled conditions. Half times in this case were in the range of several minutes to hours. It is found out that the maximum reaction rate is achieved by aging solution K 2 FeO 4 after the synthesis for 8 days. Both methods show that the oxidation rate is controlled by the concentration of protonated ferrate, . The dependence of the observed rate constants on pH, nitrite concentrations and ionic strength has been investigated. The true rate constants of reaction are found. Particular orders of the reaction by nitrite and ferrate ions and the overall order of the reaction are calculated. The oxidation rate constant of water by Fe(VI) is found. The studies presented in this paper are important because the oxidation kinetics of harmful inorganic and organic substances by ferrates(VI) of alkali metals is widely used to determine the optimal parameters of technological processes for the purification of surface water, industrial wastewater and air.

In the present study, we reassessed whether angiotensin (Ang)-(1-7) can exert short- and long-term cardiovascular effects because there has been a resurgence of interest in this N-terminal heptapeptide fragment of Ang II. In particular, we studied 3 aspects relating to the reported cardiovascular effects of Ang-(1-7): does this peptide (1) potentiate the hypotensive effect of bradykinin in normotensive Wistar-Kyoto rats and spontaneously hypertensive rats (SHR), (2) cause a depressor effect after long-term treatment in SHR, and (3) contribute to the antihypertensive effects of angiotensin-converting enzyme inhibitors? In the first series of experiments, Ang-(1-7) failed to enhance the dose-related hypotensive responses evoked by bradykinin in SHR (n=11) and Wistar-Kyoto (n=5) rats. In the second series of experiments, a 7-day intravenous infusion of Ang-(1-7) (24 microg x kg(-1) x h(-1)) decreased blood pressure in SHR (n=12) on days 4 and 5, although this effect waned despite continual Ang-(1-7) infusion. However, a new finding was that the Ang-(1-7) antagonist A-779 (24 microg x kg(-1) x h(-1) for 7 days) attenuated the depressor effect of Ang-(1-7) when given concurrently in a separate group of SHR (n=8). In the third series of novel experiments, the angiotensin-converting enzyme inhibitor perindopril was given in drinking water for 7 days (0.3 mg. kg(-1) x day(-1)), either alone (n=6) or combined with an intravenous infusion of A-779 (24 microg x kg(-1) x h(-1) for 7 days, n=8). Although this dose of A-779 attenuated the depressor effect of Ang-(1-7), it did not alter the antihypertensive effect caused by perindopril. Thus, the present results contrast with a number of previous studies and argue against Ang-(1-7) playing a major role in blood pressure regulation.

A multimode perturbation method for frequency response analysis of nonlinearly vibrational beams with periodic distribution parameters is proposed. The partial differential equation with spatial varying parameters for nonlinear vibration of beams with periodic parameters under harmonic excitations is derived. The procedure of the multimode perturbation method includes three main steps: first, the nonlinear partial differential equation is transformed into linear partial differential equations with varying parameters by applying perturbation method; second, the linear partial differential equations are transformed into ordinary differential equations with multimode coupling by applying Galerkin method, where multiple vibration modes of the beams are used and the equations are suitable to nonlinear vibration of periodic structures with high parameter-varying wave in wide frequency band; third, the ordinary differential equations are solved by applying harmonic balance method to obtain vibration response of the nonlinear periodic beam, which is used for characteristics analysis of frequency response and spatial mode. Furthermore, the stability problem of nonlinear harmonic vibration as multidegree-of-freedom system with periodic time-varying parameters is solved by applying direct eigenvalue analysis approach. The proposed method can incorporate multiple vibration modes into response analysis of nonlinear periodic structures and consider mode-coupling effects due to structural nonlinearity and parametric periodicity. Finally, a nonlinear beam with periodic supports under harmonic excitations is studied. Numerical results on frequency response of the beam are given to illustrate an application of the proposed method, new frequency response characteristics, and influences of periodic parameters on structural response. The results have potential application to nonlinear structural vibration control and support damage detection of nonlinear structures with periodic supports.

Forgetting at short term: When do event-based interference and temporal factors have an effect?

&lt;p&gt;Thermodiffusion or Soret effect is a heat and mass transfer phenomenon in a non-isothermal liquid and gas mixtures. This phenomenon is more pronounced in oil fields, usually due to the porous environment. A precise and better understanding of the thermodiffusion phenomena in multi-component mixtures results in a more accurate modeling of oil reservoirs. Accordingly, the main objective of this study is to investigate the thermodiffusion phenomenon in the multicomponent mixtures. In order to achieve this objective, two series of thermodiffusion experiments conducted on board the International Space Station (ISS) using the SODI (Selectable Optical Diagnostics Instrument) facility were analyzed. The first series of experiments aimed to study the effects of the forced vibration on the Soret phenomena. The experimental mixture was water and isopropanol with different compositions subjected to various temperature gradients normal to the vibrations. Results revealed maximum separation for the case with the minimum vibration and the lower temperature gradient; however, a linear relationship between Gershuni number and maximum separation was not found. On the other hand, the second series of experiment was aimed to the measurement of the diffusion coefficients of selected ternary mixtures. Mixtures of tetrahydronaphthalene-isobutylbenzene-dodecane at five different compositions were hosted in the DSC (Diffusion and Soret Coefficient) cell array. Thus, the Soret diffusion coefficients and the molecular diffusion coefficients of the mentioned hydrocarbon mixture at five different compositions have been reported. To process the results of these experiments an advance image processing technique was developed and implemented in an application with GUI (Graphical User Interface) for the Mach-Zehnder interferometer (MZI). Then, the application of the windowed Fourier transformation (WFT) to analyze the heat and mass transfer problem using the MZI setup is proposed. Results show that the WFT noticeably improves the measurement of concentration. This improvement is more evident for the ternary. It was shown that about 10% underestimation of the Soret coefficient would be resulted; if an accurate determination of the thermal time for the MZI is not used. The reliability and the repeatability of the MZI apparatus on board ISS to study thermodiffusion for binary and ternary mixtures were shown.&lt;/p&gt;

Three series of experiments were conducted on vertical clamped-clamped cylinders in order to observe experimentally the dynamical behaviour of the system, and the results are compared with theoretical predictions. In the first series of experiments, the downstream end of the clamped-clamped cylinder was free to slide axially, while in the second, the downstream end was fixed; the influence of externally applied axial compression was also studied in this series of experiments. The third series of experiments was similar to the second, except that a considerably more slender, hollow cylinder was used. In these experiments, the cylinder lost stability by divergence at a sufficiently high flow velocity and the amplitude of buckling increased thereafter. At higher flow velocities, the cylinder lost stability by flutter (attainable only in the third series of experiments), confirming experimentally the existence of a post-divergence oscillatory instability, which was previously predicted by both linear and nonlinear theory. Good quantitative agreement is obtained between theory and experiment for the amplitude of buckling, and for the critical flow velocities.

SummaryTwins deriving from a single zygote were produced in Triton alpestris and Triton taeniatus by two different series of experiments. The first type of experiments proceeded, by means of a glass thread put on and cutting through the median plane of early gastrulae, to a division of these into two lateral (right and left) halves. These halves may give rise to normally formed identical twins (fig. 2), or to twins with more or less accentuated deficiencies on their inner sides (figg. 3 and 4). In extreme cases they may even produce left or right half-embryos, or much reduced malformations with very imperfect organ formation. Generally considered, the regolation in the head region is better than that in the tail one, and much better than in the trunk. Most of the heads show two eyes of equal size and normal position; in rare cases we encounter two eyes of different size, or synophthalmus or cyclopia. The «real» half-embryos have only one laterally situated eye (tab. 2). The normally formed identical twins deriving from half an egg each, develop into properly proportionned embryos of half the normal size; the resulting larvae reach the normal size of the equally-aged control larvae deriving from entire eggs, often before the stage of nourishment, (fig. 5, tab. 3).In the second series of experiments, an early gastrula was cut through in correspondence to the median plane, and then the complete presumptive epidermis of another gastrula and, respectively, of a third one, was stuck on to the wound surfaces of the halves in normal orientation (fig. 6). The right and the left combinations resulting therefrom give rise, in the original median line, to long, narrow and apparently somewhat too great neural plates, the external half-portion of which was fournished by the host half-gastrula and is somewhat more strongly developped than the inner half-portion deriving from the presumptive epidermis (fig. 7 a, b). This epidermis that was stuck on to the gastrula-halves' surfaces, takes part in the formation of the embryos either totally or at least for its greatest part. No perfect larvae will be formed (tab. 4). The head is always bilaterally developped, but it is often asymmetric and shows synophthalmous or cyclopic character (figg. 8, 9, 10, tab. 5). The trunk is sometimes normal (fig. 8 a), but it may also show an axial system of too great length (fig. 8 b), or dorsal deficiencies—often in the form of either symmetrical or asymmetrical Spina bifida—with dorsal incurvation (fig. 9 a, b). The tail can be either normal, or crooked, or defective, or doubled. In the best cases we see, in the first series of experiments, the regolation of the half-organiser of the gastrula-half into an entire organiser of half the normal size, while, in the second series of experiments, the regolation can produce an approximately normally sized entire organiser, which however, in the anterior head region is lacking of its full indutcive capacity.In both series of experiments the right hand member of the twins was observed to show inversion of the situs viscerum.

In pedestrian inertial navigation, one possible placement of Inertial Measurement Units (IMUs) is on a footwear. This placement allows to limit the accumulation of navigation errors due to the bias drift of inertial sensors and is generally a preferable placement of sensors to achieve the highest precision of pedestrian inertial navigation. However, inertial sensors mounted on footwear experience significantly higher accelerations and angular velocities (10s of g and 1000s of deg/sec) during regular pedestrian activities than during more conventional navigation tasks, which could exceed Full Scale Range (FSR) of many commercial-off-the-shelf IMUs, therefore degrading accuracy of pedestrian navigation systems. This paper proposes a reconstruction filter to mitigate localization error in pedestrian navigation due to insufficient FSR of inertial sensors. The proposed reconstruction filter approximates immeasurable accelerometer’s signals with a triangular function and estimates the size of the triangles using a Gaussian Process (GP) regression. To evaluate performance of pedestrian navigation systems enhanced by the proposed reconstruction filter, we conducted two series of indoor pedestrian navigation experiments with a VectorNav VN-200 IMU and an Analog Device ADIS16497-3 IMU, which have accelerometer’s FSR of ±16 g and ±40 g, respectively. In the first series of experiments, forces experienced by the foot-mounted IMUs did not exceed the FSRs of the sensors, while in the second series, the forces surpassed the FSR of the VN-200 IMU and saturated the accelerometer’s readings. The saturated accelerometer’s readings reduced the accuracy of estimated positions using the VN-200 by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.34}\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${3.37}\times $ </tex-math></inline-formula> along horizontal and vertical directions. When applying our proposed reconstruction filter to the saturated accelerometer’s measurements, the navigation accuracy along horizontal and vertical directions was increased by 5% and 50%, respectively, as compared to using unreconstructed signals.