Variation Of Peak Height Research Articles

Evaluation of Welding Current Impact on Residual Stresses Status in Ship-Building Steel Weldments Using Barkhausen Noise

The paper intends to determine the relationship between heat input and the residual stresses distribution in shipbuilding steel weldments using the Magnetic Barkhausen Noise (MBN) technique. The rate of fusion during welding was controlled by amount and time of fusion for a given weld bead width. Barkhausen noise measurements were performed parallel to the weld bead at the back of the plates welded using variable welding currents along the line that crosses the weld bead. The heat affected zones were differentiated by a variation in MBN peak height. The high welding current was characterized by high MBN amplitude compared with the medium and the low currents. The results showed that the heat affected zone was narrower with high welding current and increases with decreasing current. The results indicate that residual stresses introduced in steel by welding could be mapped nondestructively by magnetic Barkhausen noise

Evaluation of Welding Current Impact on Residual Stresses Status in Ship-Building Steel Weldments Using Barkhausen Noise

The paper intends to determine the relationship between heat input and the residual stresses distribution in shipbuilding steel weldments using the Magnetic Barkhausen Noise (MBN) technique. The rate of fusion during welding was controlled by amount and time of fusion for a given weld bead width. Barkhausen noise measurements were performed parallel to the weld bead at the back of the plates welded using variable welding currents along the line that crosses the weld bead. The heat affected zones were differentiated by a variation in MBN peak height. The high welding current was characterized by high MBN amplitude compared with the medium and the low currents. The results showed that the heat affected zone was narrower with high welding current and increases with decreasing current. The results indicate that residual stresses introduced in steel by welding could be mapped nondestructively by magnetic Barkhausen noise.

Investigation on dual wire TIG Arc additive manufacturing of IN625 and SS316L FGM for continuous gradient and sandwich structures

Fabrication of functionally graded material (FGM) has been studied using dual wire WAAM-TIG (wire arc additive manufacturing - tungsten inert gas) process. The experimental research aims to perform the feasibility study of different designs of FGMs, including continuous gradient (CG-FGM) and sandwich structures (SW-FGMs). The weight percentage of two wire materials, SS316L and IN625, was precisely controlled using individual wire feeding systems. Process parameters were identified to obtain the defect-free deposition for the desired combination of weight percentage. The governing elements, i.e., Ni and Fe, showed a gradual variation in the case of CG-FGM and alternate peaks for SW-FGMs while examined using energy-dispersive X-ray spectroscopy (EDS). The alternate material distinction was noticeable with the increase in the number of individual layers for each set of SW-FGMs. The microstructure evolution of CG-FGM showed a smooth transition from equiaxed to columnar dendrites along the build direction, while SW-FGM showed heterogeneous behaviour. The hardness was steadily increasing in CG-FGMs and formed a wavy pattern in SW-FGMs. X-ray diffraction (XRD) analysis confirmed the formation of the austenitic phase, and variation in peak heights correlates to the change in microstructure and hardness. The conducted tribological study showed the specific wear rate gradually decreased with an increase of Ni content in CG-FGM, whereas in SW-FGM, it showed a strong dependency on the adopted design. The alloying effect in SW-FGM with different design modalities and its comparison with equal weight percentages were also studied in detail and presented.

Experimental investigation of road surface parameters affecting tire/road noise

It is known that tire/road noise is strongly affected by the properties of the road surface such as its profile and sound absorption coefficient. Several parameters, represented by mean profile depth (MPD), have been proposed or standardized as surface profile parameters, but none of them clearly explains the relationship with tire/road noise generation. This study attempted to identify a new surface parameter that correlates more closely with tire/road noise. Surface profile measurements and close proximity (CPX) measurements were conducted on several road surfaces with different properties on test tracks. Tire P1, the reference tire for the CPX method, and two types of passenger car tires were used for the CPX measurements. According to our experience, the variation of the peak height of the road surface with distance is closely related to the excitation input to the tires and thus noise generation. Therefore, we devised a road profile parameter to quantitatively evaluate the variation of peak height. A relatively strong correlation was observed between this parameter and the CPX level. The validity of this parameter will be verified by further measurements on general roads in the future.

A comparative evaluation of forensic STR kits and their tolerance to PCR inhibitors

ABSTRACT DNA samples used in forensic DNA analysis, especially casework evidence samples, are usually collected in diverse and harsh environments and often contain PCR inhibitors. DNA extracted from casework evidence samples is likely to have a low concentration. Additionally, the PCR clean-up process to remove PCR inhibitors can decrease DNA concentration. Therefore, through this study, we aimed to compare the inhibitor tolerance of short tandem repeat (STR) kits and identify their strengths and weaknesses in order to effectively apply and utilize the kits in forensic science. Inhibitor tolerance analysis of STR kits was conducted by measuring the peak height, limit of detection (LOD), and peak balance. The effect of the inhibitor on the peak height variation was determined using the effective concentration 50 (EC50) value. Inhibitor tolerance indicators, such as the LOD and peak balance of each kit, were measured in the presence of four inhibitors, including humic acid, haematin, calcium phosphate, and indigo carmine. No significant difference was observed for the inhibitors for each of the STR kits tested, with the exception of the Investigator® 24plex QS kit which had a significantly higher tolerance for calcium phosphate.

Impact of recombination mechanisms on the capacitance-voltage characteristics in bulk heterojunction organic solar cells

Low frequency Capacitance- voltage (C-V) measurements have been employed to investigate the effect of thickness variation of poly (3-hexylthiophene (P3HT) and fullerene [6,6],-phenyl-C61-butyric acid methyl ester(PCBM) based Bulk Heterojunction (BHJ) photo absorbing layer in inverted organic solar cell (OSC) configuration, ITO|ZnO|P3HT:PCBM|MoO3|Ag and are corelated with different recombination mechanisms. The normalized capacitance (CCgeom) with voltage curves at different P3HT: PCBM blend thicknesses such as 130, 100, 80 and 70 nm demonstrate an increase in peak height with thickness as well as the presence of negative capacitance (NC) beyond peak voltage for higher thicknesses. To understand both peak height variation and the occurrence of NC, a defect sensitive simulation study has been performed by employing the radiative and non-radiative recombination processes. Based on the analysis of simulation results we confirm the role of Langevin bimolecular recombination rate in determining the peak height with thickness; however, the presence of NC in C-V curves can be understood through a competition between the Langevin bimolecular, and trap assisted recombination rates. Study confirms that peak height reduces due to increase in the rate of Langevin bimolecular recombination, whilst the trap assisted recombination resurges the NC beyond peak voltage. Later, the utilities of D-D based1C23 vs V analysis to calculate built-in voltage (Vbi) have been performed for the experimental and simulation data at different thicknesses emphasizing the strength of this approach to characterize threshold voltage of organic diodes.

Phase transition and defect relaxation behavior in a medium manganese steel

Phase transition and defect relaxation behavior of a Fe-7Mn-0.1C medium manganese steel have been systematically studied mainly by using internal friction (IF) technique. From temperature-dependent IF curves in both heating and cooling processes, two relaxation IF peaks (the P1 located at ~ 200 °C on heating and the P2 at ~ 550 °C on cooling) and two phase transition IF peaks (the Ptr1 located at ~ 670 °C on heating and the Ptr2 at ~ 300 °C on cooling) were observed. The P1 peak disappears when the cementite (θ) particles and/or retained austenite (γR) exist in the microstructure, and is associated with the Snoek-Kê-Köster relaxation (SKK relaxation). The P2 peak is suggested to be originated from grain boundary relaxation in austenite (γ). The formation mechanisms of the Ptr1 and the Ptr2 come from reverse austenitic transformation (RAT) and martensitic transformation (MT), respectively. In addition, the apparent asymmetry of the Ptr1, the variation of peak height, the difference between the Ptr1 and Ptr2 peaks, and the effect of IF studies on the mechanical properties are discussed in detail in the present work. These results provide a valuable reference for the design of high-performance medium Mn steels.

Development of Methodology for Characterization of Surface Roughness of Solid Metallic Surfaces Using Oil Slippage Method

Abstract The study employed the phenomenon of friction between liquid droplets and solid metallic surfaces in surface roughness analysis of engineering materials. Five samples of mild steel plate were prepared to different degrees of surface roughness by facing operation. The sample surfaces were analysed to determine the roughness parameters (mean roughness, root mean square roughness, roughness skewness, and roughness kurtosis) and friction coefficient of the surfaces. Oil droplet sliding velocity was determined using the oil slippage test. The friction coefficient of the surfaces increased with increasing roughness parameter which varied from 26.334 µm at friction coefficient = 0.63 to 13.153 µm at friction coefficient = 0.46. The results from oil slippage test showed that the sliding velocity of the oil drop decreased as the friction coefficient of samples increased. At an inclination angle of 30°, sliding velocity varied from 0.51 cm/s at friction coefficient = 0.63 to 0.92 cm/s at friction coefficient = 0.46. Some of the samples exhibited a deviation in the trend of relationship between friction coefficient and sliding velocity which resulted from the variation in peak height of roughness between the sample surfaces. Oil slippage method predicts the surface behaviours of materials based on their surface parameters.

A new numerical correction method for gamma spectra based on the system transformation theory of random signals

The conventional correction techniques for gamma spectra usually use approximate algorithms, the calculation procedures are tedious and complicated, the obtained corrected spectra are usually the channel domain spectra even if they are calibrated by energy. Moreover, the spectra are still dependent upon system parameters themselves such as the gain of amplifier and the offset of ADC etc. In this paper, a new numerical correction method of gamma spectra was developed on the basis of the system transformation theory of random signals. By transforming the measured spectrum from the channel domain to the energy domain, the theoretical deposition energy spectrum which is energy domain spectrum, rather than channel domain spectrum can be obtained without any algorithm approximation processing. The presented method makes it possible to compare and exchange the gamma-ray spectrum data that are measured under different conditions or by different spectrometer systems equipped with the same type of detectors. To validate the method, a set of NaI (Tl) gamma spectra and three sets of HPGe gamma spectra were collected. The results show that serious spectral drifts and intensity variation in NaI (Tl) gamma spectra were effectively eliminated. The maximum relative drift of peak position, the maximum relative variation of peak height and that of FWHM before correction were 65.03%, 40.37% and 61.65%, respectively, and after correction, they became 0.19%, 2.81% and 0.85%, respectively, indicating that the method has strong ability to correct gamma spectra. HPGe gamma spectra were also well corrected using the presented method, and were identified as gamma radiation fingerprints of nuclear materials. The results show that the method can also improve the confidence degree of identifying nuclear materials significantly.

Dynamics of Binding of Lysozyme with Gold Nanoparticles: Corona Formation and its Correlation with a Naked-Eye-Based Colorimetric Approach

The interaction between colloidal gold nanoparticles (AuNPs) and lysozyme (Lyz) has been studied through spectroscopic and microscopic measurements, molecular docking simulation and colorimetric measurements to investigate corona formation and the mechanism, affinity, number of sites and stoichiometry of binding. Molecular docking simulation endorses that, at physiological pH, the interaction between basic NH2group of arginine and citrate ions is predominant than the interaction between citrate ions and the positive surface charge of the bare AuNPs that result in the desorption of citrate ions from Au surfaces and finally, electrostatic interaction between [Formula: see text] group of arginine and positive charge surface of AuNPs results in the adsorption of Lyz on Au surfaces. As observed from Benesi–Hildebrand and fluorescence analyses, the ground state complex formation between Lyz and AuNPs requires several minutes, which is approximately 11 min in the present work to attain stoichiometric ratio 1:1. CD spectra indicate insignificant or no conformational change in the secondary structure of Lyz in the presence of AuNPs. The time variation of LSPR peak position and peak height in the presence of Lyz have been studied extensively through spectroscopic and microscopic measurements. Detailed discussion on the probable time-specific roles of change in local dielectric constant, plasmon coupling and electrostatic interaction on these variations has been presented. Colorimetric change of the AuNPs-Lyz system with time has been analyzed by measuring the red, blue and green color fractions as well as its correlation with the process of corona formation and aggregation has been investigated to propose a novel naked eye colorimetric approach of studying these processes in AuNPs-Lyz system.

Validation of MaSTR™ software: Extensive study of fully-continuous probabilistic mixture analysis using PowerPlex®Fusion 2 – 5 contributor mixtures

Fully continuous probabilistic genotyping utilizes more information from the evidentiary profile; such as peak heights, stutter percentages, mixture ratio, and probability of drop-in/out, than historical approaches to provide weighted genotypes. The weighted genotypes are used to calculate a likelihood ratio that a profile is included in the mixture or not. Mixture profiles are compared to hypothetical profiles created using these parameters to calculate the probability of a given individual being a contributor to the mixture. Since direct integration over a large number of interrelated parameters is not feasible, Marcov Chain Monte Carlo (MCMC) is a widely used sampling method. This validation study of MaSTR software provides the forensic community with a report of the capabilities and reliability of this tool to assist the forensic analyst in applying their expertise to evaluate mixture profiles.The validation study was designed in accordance with SWGDAM and OSAC guidelines [1–3]. Purified, de-identified DNA from 40 donors was obtained from the Nebraska Biobank, quantified using Quantifiler® Human DNA Quantification kit, amplified with the PowerPlex®Fusion 5C system, analyzed on an ABI PRISM® 3130 Genetic Analyzer, and genotyped using GeneMarker®HID software. Results of replicates and dilutions were imported into MaSTR software to calculate the variance coefficient and stutter ratios required for the protocol data set. The protocol data set provided the software with context of expected peak height variation during the evaluation of mixtures. Two, three, four, and five-contributor mixtures with a range of contributor ratios, shared alleles, peak height variance, and dilutions were tested. The elimination database was used to evaluate MaSTR software’s contamination detection capability.

Is vacuum ultraviolet detector a concentration or a mass dependent detector?

The vacuum ultraviolet detector (VUV) is a very effective tool for chromatogram deconvolution and peak identification, and can also be used for quantification. To avoid quantitative issues in relation to time drift, such as variation of peak area or peak height, the detector response type has to be well defined. Due to the make-up flow and pressure regulation of make-up, the detector response (height of the peak) and peak area appeared to be dependent on experimental conditions such as inlet pressure and make-up pressure. Even if for some experimental conditions, VUV looks like mass-flow sensitive detector, it has been demonstrated that VUV is a concentration sensitive detector.

Evidence of prompt penetration electric fields during HILDCAA events

Abstract. High-intensity, long-duration continuous auroral electrojet (AE) activity (HILDCAA) events may occur during a long-lasting recovery phase of a geomagnetic storm. They are a special kind of geomagnetic activity, different from magnetic storms or substorms. Ionized particles are pumped into the auroral region by the action of Alfvén waves, increasing the auroral current system. The Dst index, however, does not present a significant downward swing as it occurs during geomagnetic storms. During the HILDCAA occurrence, the AE index presents an intense and continuous activity. In this paper, the response of Brazilian equatorial ionosphere is studied during three HILDCAA events that occurred in the year of 2006 (the descending phase of solar cycle 23) using the digisonde data located at São Luís, Brazil (2.33° S, 44.2° W; dip latitude 1.75° S). Geomagnetic indices and interplanetary parameters were used to calculate a cross-correlation coefficient between the Ey component of the interplanetary electric field and the F2 electron density peak height variations during two situations: the first of them for two sets daytime and nighttime ranges, and the second one for the time around the pre-reversal enhancement (PRE) peak. The results showed that the pumping action of particle precipitation into the auroral zone has moderately modified the equatorial F2 peak height. However, F2 peak height seems to be more sensitive to HILDCAA effects during PRE time, showing the highest variations and sinusoidal oscillations in the cross-correlation indices.

Preearthquake anomalous ionospheric signatures observed at low‐mid latitude Indian station, Delhi, during the year 2015 to early 2016: Preliminary results

AbstractWe have analyzed five major earthquake events measuring greater than 6 on Richter scale (M > 6) that occurred during the year 2015 to early 2016, affecting Indian region ionosphere, using F2 layer critical parameters (foF2, hmF2) obtained using Digisonde from a low‐mid latitude Indian station, Delhi (28.6°N, 77.2°E, 19.2°N geomagnetic latitude, 42.4°N dip). Normal day‐to‐day variability occurring in ionosphere is segregated by calculating F2 layer critical frequency and peak height variations (ΔfoF2, ΔhmF2) from the normal quiet time behavior apart from computing interquartile range. We find that the ionospheric F2 region across Delhi by and large shows some significant perturbations 3–4 days prior to these earthquake events, resulting in a large peak electron density variation of ~200%. These observed perturbations indicate towards a possibility of seismo‐ionospheric coupling as the solar and geomagnetic indices were normally quiet and stable during the period of these events. It was also observed that the precursory effect of earthquake was predominantly seen even outside the earthquake preparation zone, as given by Dobrovolsky et al. (1979). The thermosphere neutral composition (O/N2) as observed by Global Ultraviolet Imager, across Delhi, during these earthquake events does not show any marked variation. Further, the effect of earthquake events on ionospheric peak electron density is compared to the lower atmosphere meteorological phenomenon of 2015 sudden stratospheric warming event.

Peak height of OH airglow derived from simultaneous observations a Fabry‐Perot interferometer and a meteor radar

AbstractA new method for estimating daily averaged peak height of the OH airglow layer from a ground‐based meteor radar (MR) and a Fabry‐Perot interferometer (FPI) is presented. The first results are derived from 4 year simultaneous measurements of winds by a MR and a FPI at two adjacent stations over center China and are compared with observations from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The OH airglow peak heights, which are derived by using correlation analysis between winds of the FPI and MR, are found to generally peak at an altitude of 87 km and frequently varied between 80 km and 90 km day to day. In comparison with SABER OH 1.6 μm observations, reasonable similarity of airglow peak heights is found, and rapid day‐to‐day variations are also pronounced. Lomb‐Scargle analysis is used to determine cycles of temporal variations of airglow peak heights, and there are obvious periodic variations both in our airglow peak heights and in the satellite observations. In addition to the annual, semiannual, monthly, and three monthly variations, the shorter time variations, e.g., day‐to‐day and several days' variations, are also conspicuous. The day‐to‐day variations of airglow height obviously could reduce observation accuracy and lead to some deviations in FPI measurements. These FPI wind deviations arising from airglow height variations are also estimated to be about 3–5 m/s from 2011 to 2015, with strong positive correlation with airglow peak height variation. More attention should be paid to the wind deviations associated with airglow height variation when using and interpreting winds measured by FPI.

Exploring electro-optic effect and third-order nonlinear optical susceptibility of impurity doped quantum dots: Interplay between hydrostatic pressure, temperature and noise

We study the profiles of electro-optic effect (EOE) and third-order nonlinear optical susceptibility (TONOS) of impurity doped GaAs quantum dots (QDs) under the combined influence of hydrostatic pressure (HP) and temperature (T) taking into account the presence of Gaussian white noise. Noise has been introduced to the system additively and multiplicatively. The doped dot has been subjected to a polarized monochromatic electromagnetic field. Effect of application of noise is elegantly reflected through prominent change of peak shift (blue/red) and variation of peak height (increase/ıdecrease) of above nonlinear optical (NLO) properties as temperature and pressure are varied over a range. Interestingly, all such changes subtly depend on mode of application (additive/multiplicative) of noise. The noteworthy influence of the interplay between noise strength and its mode of application on the said NLO properties has also been critically scrutinized. The findings highlight remarkable role played by noise in tuning above NLO properties of doped QD system under the prominent presence of both hydrostatic pressure and temperature.

A comparison of mesospheric and low‐thermospheric winds measured by Fabry‐Perot interferometer and meteor radar over central China

AbstractWind data observed by a Fabry‐Perot interferometer (FPI) and a meteor radar (MR) deployed in two stations, which are 430 km apart in ground distance, are used to study wind climatology in mesosphere/lower thermosphere over central China and compare between the measurements. A general morphologic similarity of the FPI winds and MR winds is identified with 4 year data since November 2011. At 87 km, the wind vector plots show that the FPI and MR winds agree with each other very well in all months. The zonal winds of both instruments have an apparent semiannual variation with a maximal strength of −20 m/s at around 18:00 UT in equinoctial months, and the meridional winds from both instruments have an apparent annual variation with a maximal strength of −40 m/s at around 15:00 UT in summer months. The correlation coefficients between the measurements of the two instruments are about 0.95 for meridional wind and 0.90 for zonal wind. At 97 km, the wind vector plots show that FPI and MR winds agree with each other from May to October and are obviously different in the rest months. There are very weak semiannual variations at around 18:00 UT for both zonal winds and pronounced annual variation at around 13:00 UT for both meridional winds. The correlation coefficients between the FPI and MR winds are 0.73 for zonal wind and 0.86 for meridional wind, which are overall smaller than that at 87 km. A Gaussian distribution of airglow profile is used to investigate the deviations associated with peak height and full width at half maximum (FWHM) of airglow layer. It is found that the variation of peak height could lead to about 20% variation of correlation coefficients between measurements at the height of 87 km and about 14.8% at the height of 97 km on average. The variation of FWHM could lead to a correlation coefficient variation of about 2.4% and 3.5% at the height of 87 km and 97 km, respectively. Some other reasons, such as the influence of geomagnetic field on meteor trail and the propagation of gravity waves, could also contribute to these differences between measurements.

Modulating optical rectification, second and third harmonic generation of doped quantum dots: Interplay between hydrostatic pressure, temperature and noise

We examine the profiles of optical rectification (OR), second harmonic generation (SHG) and third harmonic generation (THG) of impurity doped QDs under the combined influence of hydrostatic pressure (HP) and temperature (T) in presence and absence of Gaussian white noise. Noise has been incorporated to the system additively and multiplicatively. In order to study the above nonlinear optical (NLO) properties the doped dot has been subjected to a polarized monochromatic electromagnetic field. Effect of application of noise is nicely reflected through alteration of peak shift (blue/red) and variation of peak height (increase/decrease) of above NLO properties as temperature and pressure are varied. All such changes again sensitively depends on mode of application (additive/multiplicative) of noise. The remarkable influence of interplay between noise strength and its mode of application on the said profiles has also been addressed. The findings illuminate fascinating role played by noise in tuning above NLO properties of doped QD system under the active presence of both hydrostatic pressure and temperature.

General Theory for Pulse Voltammetric Techniques on Rough and Finite Fractal Electrodes for Reversible Redox System with Unequal Diffusivities

The prediction of voltammetric response from the microscopic information of the electrode surface morphology is an important problem of fourth generation electrochemistry which we have theoretically addressed here. We develop a theory for pulse based voltammetric response of reversible charge transfer process with unequal diffusivities on randomly rough electrode. The microscopic information of the electrode surface is incorporated into the response expression in the form of power spectrum of roughness. An elegant expression for the statistically averaged generalized pulse voltammetric current is obtained in terms of single potential step current at rough electrode from which, the explicit current expressions for differential pulse (DPV), staircase (SCV), cyclic staircase (CSCV) and square wave (SWV) voltammetries are obtained for random and finite fractal roughness electrode. The SCV and CSCV responses, as elaborately discussed in our previous work, here we have focused more on the explorations of DPV and SWV responses. In the presence of equal diffusion coefficients of the electroactive species, roughness induces enhancement in the peak heights with retention of peak position at the same potential for DPV as well as SWV. This points towards an enhanced sensitivity of these differential techniques at rough electrodes. In the presence of unequal diffusivities of redox species, SWV shows a distinguished signature of roughness due to variation in peak heights along with alteration in the position of the peaks. Square wave voltammetry on rough electrode shows an asymmetric suppression in the peak height of the anodic or cathodic sampled current plots due to unequal diffusivities which resembles the behavior of a chemically irreversible system.

Exploring the Impacts of Ordinary Laboratory Alterations During Forensic DNA Processing on Peak Height Variation, Thresholds, and Probability of Dropout.

Impacts of validation design on DNA signal were explored, and the level of variation introduced by injection, capillary changes, amplification, and kit lot was surveyed by examining a set of replicate samples ranging in mass from 0.25 to 0.008 ng. The variations in peak height, heterozygous balance, dropout probabilities, and baseline noise were compared using common statistical techniques. Data indicate that amplification is the source of the majority of the variation observed in the peak heights, followed by capillary lots. The use of different amplification kit lots did not introduce variability into the peak heights, heterozygous balance, dropout, or baseline. Thus, if data from case samples run over a significant time period are not available during validation, the validation must be designed to, at a minimum, include the amplification of multiple samples of varying quantity, with known genotype, amplified and run over an extended period of time using multiple pipettes and capillaries.