Distortion Of Spectrum Research Articles

Design and Implementation of Real Time Object Invisibility

This paper focuses on Real time Invisibility of object. That means how object can be made invisible or get disappear. Main Objective of this project is to design, develop and demonstrate a state of art technology invisibility (Cloaking) by employing combination of various techniques and components such as electro – optical sensors, signal polarization, spectrum distortion, exploitation of thermal properties of technology and nano technology. Concept is that whatever object that we can see in this universe have some symmetrical internal structure because of which it reflects object and hence we can see it. Therefore we need to design material which has internal structure differ from object/ material which exists in universe. Such kind of material is known as metamaterial. Metamterial can be designed by mixing two different material in which one material is insulator. In this paper, after performing several experiments we have proposed two ways through which invisibility can be achieved: 1. By using metamaterials, 2. By Lubor lenses. This project has following applications: 1. In military field: to make our military bases, equipments etc invisible, 2. In medical field: to perform operation without cutting the body parts.

Development of a Shock and Detonation Velocity Measurement System Using Chirped Fiber Bragg Gratings.

Dynamic measurements of shock and detonation velocities are performed using long chirped fiber Bragg gratings (CFBGs). Such thin probes, with a diameter of typically 125 µm or even 80 µm can be directly inserted into high-explosive (HE) samples or simply glued laterally. During the detonation, the width of the optical spectrum is continuously reduced by the propagation of the wave-front, which physically shortens the CFBG. The light power reflected back shows a ramp-down type signal, from which the wave-front position is obtained as a function of time, thus yielding a detonation velocity profile. A calibration procedure was developed, with the support of optical simulations, to cancel out the optical spectrum distortions from the different optical components and to determine the wavelength-position transfer function of the CFBG. The fitted slopes of the X–T diagram give steady detonation velocity values which are in very good agreement with the classical measurements obtained from discrete electrical shorting pins (ESP). The main parameters influencing the uncertainties on the steady detonation velocity value measured by CFBG are discussed. To conclude, different HE experimental configurations tested at CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) are presented: bare cylindrical sticks, wedges for shock-to-detonation transitions (SDT), spheres, a cast-cured stick around a CFBG, and a detonation wave-front profile configuration.

Latest result of solar neutrino analysis in Super-Kamiokande

Super-Kamiokande (SK), a 50 kton water Cherenkov detector in Japan, is observing neutrinos and searching for proton decay and neutrino produced by dark matter. In solar neutrino analysis, SK studies the effects of both the solar and terrestrial matter density on neutrino oscillations: a distortion of the solar neutrino energy spectrum would be caused by the edge of the Mikheyev-Smirnov-Wolfenstein resonance in the solar core, and terrestrial matter effects would induce a day/night solar neutrino flux asymmetry. The installation of new front-end electronics in 2008 marks the beginning of the 4th phase of SK (SK-IV). On 2018 May, we finished taking data of SK-IV and started the refurbishment work in order to clean the inside of the detector and to seal the water tank to prevent water tank toward SK-Gd. In this proceedings, we overview the latest solar neutrino results in SK-IV, for example, the precise measurement of 8B solar neutrino flux, its energy spectrum and oscillation parameters. In addition, we discuss the future prospect of the new phase of SK-V.

Cosmological information content in redshift-space power spectrum of SDSS-like galaxies in the quasinonlinear regime up to k=0.3 h Mpc−1

Clustering properties and peculiar velocities of halos in large-scale structure carry a wealth of cosmological information over a wide range of scales from linear to nonlinear scales. We use halo catalogs in a suite of high-resolution $N$-body simulations to construct mock catalogs of galaxies that resemble the SDSS-like luminous early-type galaxies at three redshift bins in the range $0.15\le z\le 0.7$. To do this we include 10 nuisance parameters to model variations in halo-galaxy connections for each redshift bin; the halo occupation distribution, and the spatial and velocity distributions of galaxies in the host halos. We evaluate the Fisher information matrix for the redshift-space power spectrum of SDSS-like galaxies using different sets of the mock catalogs that are generated from changes in each of model parameters; cosmological parameters ($\sigma_8$ and $\Omega_{\rm m}$), the halo-galaxy connection parameters, and the cosmological distances ($D_{\rm A}$ and $H$ parameters at each redshift bin) for modeling an apparent geometrical distortion of the redshift-space power spectrum (the Alcock-Paczynski effect). We show that combining the monopole and quadrupole power spectra of galaxies allows for accurate estimations of the cosmological parameters and the cosmological distances, even after marginalization over the halo-galaxy parameters, by lifting the parameter degeneracies that are otherwise inevitable if either of the two spectra alone is used. When including the galaxy power spectrum information up to $k=0.3\,h\,$Mpc$^{-1}$, we find about factor of 6 gain in the cosmological information content of ($\sigma_8,\Omega_{\rm m},D_{\rm A}$'s and $H$'s) compared to $k=0.2\,h\,$Mpc$^{-1}$.

Ultrafast laser induced structural dynamics probed by time-resolved photoelectron spectroscopy

SynopsisThis work aims to study laser-induced lattice dynamics when there is strong electron-lattice temperature non-equilibrium for which the material properties are poorly known. The proposed experimental technique is time-resolved photoelectron spectroscopy (Tr-PES). The main challenges of such technique are the superposition of pump and probe spectra and the distortion of the probe spectra due to the interaction with pump-induced electrons, called space charge effect (SCE). We strongly reduced this effect by tuning the 100eV XUV beamline we have developed, enabling us to investigate Copper samples.

Perceptual Evaluation of Signal-to-Noise-Ratio-Aware Dynamic Range Compression in Hearing Aids.

Dynamic range compression is a compensation strategy commonly used in modern hearing aids. Fast-acting systems respond relatively quickly to the fluctuations in the input level. This allows for more effective compression of the dynamic range of speech and hence enhanced the audibility of its low-intensity components. However, such processing also amplifies the background noise, distorts the modulation spectra of both the speech and the background, and can reduce the output signal-to-noise ratio (SNR). Recently, May et al. proposed a novel SNR-aware compression strategy, in which the compression speed is adapted depending on whether speech is present or absent. Fast-acting compression is applied to speech-dominated time–frequency (T-F) units, while noise-dominated T-F units are processed using slow-acting compression. It has been shown that this strategy provides a similar effective compression of the speech dynamic range as conventional fast-acting compression, while introducing fewer distortions of the modulation spectrum of the background and providing an improved output SNR. In this study, this SNR-aware compression strategy was compared with conventional fast- and slow-acting compression in terms of speech intelligibility and subjective preference in a group of 17 hearing-impaired listeners with varying degree of hearing loss. The results show a speech intelligibility benefit of the SNR-aware compression strategy over the conventional slow-acting system. Furthermore, the SNR-aware approach demonstrates an increased subjective preference compared with both conventional fast- and slow-acting systems.

Recent Solar neutrino Results from Super-Kamiokande

Super-Kamiokande (SK), a 50 kton water Cherenkov detector in Japan, is observing neutrinos and searching for proton decay and dark matter. The installation of new front-end electronics in 2008 marks the beginning of the 4th phase of SK (SK-IV). With the improvement of the water circulation system, calibration methods, reduction cuts, this phase achieved the lowest energy threshold thus far: 3.5 MeV kinetic energy. SK studies the effects of both the solar and terrestrial matter density on neutrino oscillations: a distortion of the solar neutrino energy spectrum would be caused by the edge of the Mikheyev-Smirnov-Wolfenstein resonance in the solar core, and terrestrial matter effects would induce a day/night solar neutrino flux asymmetry. SK observed solar neutrino interactions for more than 20 years. This long operation covers about ∼2 solar activity cycles. An analysis about a possible correlation between solar neutrino flux and 11 year activity cycle will be presented.

Portable spectral device for monitoring plant stress conditions

The non-destructive monitoring systems use for plant stress conditions detecting and evaluating can improve the performed research and working procedures quality significantly. Such systems concepts are based on obtaining of the leaves’ reflective characteristics, the spectrum, and the chlorophyll fluorescence induction. By several methods combining for plant stress states detection within a single device, for different crops, it is possible to increase the evaluation accuracy and extend the device functionality. The laboratory prototype of the device for plants’ stress states determining was developed and tested on plants of basil garden variety. It was shown that the impact of the stress factor in the form of the UV-C radiation was expressed in the shape change of the fluorescence spectrum, namely, in the fluorescence intensity fall in the long-wave part of the spectrum. Also it was shown that the reflectivity decreased in the green and far red regions of the spectrum. At the spectra registration in the red and IR sections of the spectrum, some noises and interference distortions were detected, which can be filtered out by ways of demodulation and calculation of the trigonometric component of the interference distortion functions.

Interweaving Network: A Novel Monochromatic Image Synthesis Method for a Photon-Counting Detector CT System

With the growing technology of photon-counting detectors (PCD), spectral CT is an important topic for its potential in material differentiation. However, direct reconstruction of the detected spectrum without any compensation will lead to inaccurate results due to some non-ideal factors such as cross talk and pulse pile-up in the detectors. Conventional methods try to model these factors using calibrations and make compensations accordingly, but the results depend on the model calibration accuracy. In this paper, we proposed an Interweaving Network (WeaveNet), a novel deep learning-based monochromatic image synthesis method working in sinogram domain. Unlike previous deep learning-based methods, the WeaveNet architecture was designed based on the factor of spectrum distortion and it can solve this problem better in an intuitive way. The method was tested on a cone-beam CT (CBCT) system equipped with a PCD. After FDK reconstruction of the synthesized monochromatic projection, we evaluated the accuracy of linear attenuation coefficient, decomposition coefficient and separation angle of different materials to examine the performance of our method. This method gives more accurate results with less noise than previous methods, which demonstrates the advantages of this monochromatic image synthesis method.

Propagation of megawatt subpicosecond light pulses with the minimum possible shape and spectrum distortion in an air- or argon-filled hollow-core revolver fibre

We have examined the feasibility of undistorted subpicosecond pulse transmission at peak powers of up to 100 MW and a wavelength of 1030 nm in a hollow-core revolver fibre having a core filled with atmospheric air or argon. A hollow-core revolver fibre has been fabricated which has a low-dispersion (β2 ≈ – 0.25 ps2 km−1) transmission band in the spectral range of ytterbium and neodymium lasers. Conditions for the nonlinear (soliton) regime of megawatt picosecond pulse propagation over up to 1-km lengths of revolver fibre in atmospheric air and argon at pressures in the range 10−5 to 1 atm have been found theoretically. We have experimentally demonstrated transmission of pulses of 0.8-ps duration and up to ∼100-MW power over an ∼3-m length of revolver fibre with the minimum possible distortion of their shape and spectrum.

Measurements with a TRISTAN prototype detector system at the “Troitsk nu-mass” experiment in integral and differential mode

Sterile neutrinos emerge in minimal extensions of the Standard Model which can solve a number of open questions in astroparticle physics. For example, sterile neutrinos in the keV-mass range are viable dark matter candidates. Their existence would lead to a kink-like distortion in the tritium β-decay spectrum. In this work we report about the instrumentation of the Troitsk nu-mass experiment with a 7-pixel TRISTAN prototype detector and measurements in both differential and integral mode. The combination of the two modes is a key requirement for a precise sterile neutrino search, as both methods are prone to largely different systematic uncertainties. Thanks to the excellent performance of the TRISTAN detector at high rates, a sterile neutrino search up to masses of about 6 keV could be performed, which enlarges the previous accessible mass range by a factor of 3. Upper limits on the neutrino mixing amplitude in the mass range < 5.6 keV (differential) and < 6.6 keV (integral) are presented. These results demonstrate the feasibility of a sterile neutrino search as planned in the upgrade of the KATRIN experiment with the final TRISTAN detector and read-out system.

Facile synthesis of IrO2 nanoparticles decorated @ WO3 as mixed oxide composite for outperformed oxygen evolution reaction

Oxygen evolution reaction (OER) electrocatalysts play the critical role in efficiency and durability for different hydrogen production systems. We have successfully synthesized the earth abundant WO3 coupled with IrO2 as mixed oxide composite by a facile two-step chemical method. 50% reduction in noble metal contents (IW-50) followed by two times enhancement in activity, four-folds increase in bulk mass specific activity along with the stability of mixed oxide composite as compared to state –of –the art IrO2 catalyst are affirmed. Superior performance of mixed oxide composites are perceived due to four times increase in electrochemical surface area, reduction of Tafel slope, four-fold increase of turn over frequency, electronic distortion in Ir-4f spectrum of IW-50 along with the bridging of lattice oxygen atoms between iridium and tungsten metals. We believe that it would open up the new avenues for effective utilization of noble metal with high valence tungsten metal in corrosive environment.

Reconfigurable positron annihilation lifetime spectrometer utilizing a multi-channel digitizer

Abstract Positron annihilation lifetime (PAL) spectroscopy is a powerful tool to study atomic-scaled microstructure of materials. But PAL spectra can be easily distorted, then one will get wrong conclusions. Conventional PAL spectrometers have been widely used but the data processing capability is limited. In order to deal with the generally existed problems related to spectra distortion, and find an economic way to let conventional PAL spectrometers have better performance, we design a reconfigurable PAL spectrometer based on conventional electronic system, multi-channel digitizer card, and LaBr 3 scintillator. By using several data processing methods, analysis results of PAL spectra show significant improvements. We discuss the reasons that cause PAL spectra distortion, and try to figure out how our methods can bring changes. Related works including PAL spectra simulation and Geant4 energy deposition simulation have been done. Several other functions such as time walk offset have been developed to improve the performance of whole system. The spectrometer is still capable to add more functions if needed.

СПОСІБ АВТОМАТИЧНОГО ВИЗНАЧЕННЯ НЕСУЧОЇ ЧАСТОТИ КОРОТКОТРИВАЛИХ СИГНАЛІВ ІЗ ЧАСТОТНОЮ МАНІПУЛЯЦІЄЮ

Method for determination of the carrier frequency of short-time frequency-shift keying signals based on searching for dominant harmonics whose frequency difference is close to the subcarrier spacing frequency is proposed in the article. In telecommunication systems with burst transmissions, the symbol distribution law of the modulating sequence is not always uniform, which under a limited signal duration leads to an increase in the errors in determining the frequency-shift keying parameters. The increase in errors is due to distortion of the amplitude-frequency spectrum of the signal and a decrease in the probability of the correct identification of the subcarrier oscillations harmonics. To improve the accuracy of determining the carrier frequency proposed method uses a priori information about the value of the spacing frequency of the subcarrier oscillations and the multiplicity of frequency-shift keying. The developed approach consists in obtaining the amplitude-frequency spectrum of the signal, calculating the search threshold of dominant harmonics, determining their frequencies which correspond to subcarrier oscillations, and calculating the carrier frequency as their arithmetic mean value. To calculate the signal spectrum was used the modified Welch periodogram method with has a low dispersion of spectral estimates. The harmonic search threshold is determined automatically based on the statistical characteristics of the amplitude-frequency spectrum. Among harmonics with amplitudes greater than the threshold value, those are determined that the frequency difference between which is closest to the subcarrier spacing frequency. The simulations performed in the MATLAB software environment showed that the error in determining the carrier frequency was halved compared to the classical approach under signal-to-noise ratio from -15 dB, and the developed method was efficient if the symbol appearance probability were from 0,5 to 0,8.

γW Box Inside Out: Nuclear Polarizabilities Distort the Beta Decay Spectrum.

I consider the γW-box correction to superallowed nuclear β decays in the framework of dispersion relations. I address a novel effect of a distortion of the emitted electron energy spectrum by nuclear polarizabilities and show that this effect, while neglected in the literature, is sizable. The respective correction to the β^{+} spectrum is estimated to be Δ_{R}(E)=(1.6±1.6)×10^{-4}E/MeV assuming a conservative 100% uncertainty. The effect is positive definite and can be observed if a high-precision measurement of the positron spectrum is viable. If only the full rate is observed, it should be included in the calculated Ft values of nuclear decays. I argue that this novel effect should be included in the analyses of nuclear beta decay experiments to ensure the correct extraction of V_{ud} from decay rates, and of the Fierz interference term from precision measurements of decay spectra.

Progress Report on Proton Conducting Solid Oxide Electrolysis Cells

AbstractThe proton‐conducting solid oxide electrolysis cell (H‐SOEC) is a promising device that converts electrical energy to chemical energy. H‐SOECs have been actively studied in the past few years, due to their advantages over oxygen‐ion‐conducting solid oxide electrolysis cells (O‐SOECs), such as lower operation temperature, relatively lower activation energy, and easier gas separation. A critical overview of recent progress in H‐SOECs is presented, focusing particularly on the period from 2014 to 2018. This review focuses on three aspects of H‐SOECs, namely, the materials, modeling, and current leakage in proton conducting oxide electrolytes. Specifically, the current leakage in proton conducting oxides, which is often neglected, leads to two problems in the studies of H‐SOECs. One is the distortion of the electrochemical impedance spectra and the other is low faradaic efficiency of electrolysis. Based on the comprehensive and critical discussion in these three sections, challenges in the development of H‐SOECs are highlighted and prospective research in H‐SOECs is outlined.

Pile-up correction algorithm for high count rate gamma ray spectroscopy

In nuclear applications related to radiation energy measurement, digital pulse processing for fast sampling facility has great advantages compared to the traditional analog pulse processing. A distortion in energy spectrum and degradation in timing resolution take place when pulse pile-up occurs. This in turn leads to degradations of the signals used in applications such as nuclear medicine. Pile-up pulses are commonly removed in most algorithms if they are detected, but in this case, getting a clean spectrum becomes a challenge due to data loss. A proposed pile-up detection and recovery algorithm based on fitting the preamplifier data and signal extrapolation is presented. The extrapolated pulse is used for recovering (extracting) the piled-up pulse to estimate its parameters. A smoothed first derivative algorithm is used for peak tracking inside the detected events. To evaluate the proposed pile-up recovery algorithm theoretically and experimentally, it is applied on both simulated input signals generated with different time displacements between the piled-up events, and experimental preamplifier radiation signals. The obtained results prove that the proposed algorithm achieves better utilization of power and can be used for high count rate (high activity elements) spectroscopy systems.

A Joint Learning Algorithm for Complex-Valued T-F Masks in Deep Learning-Based Single-Channel Speech Enhancement Systems

This paper presents a joint learning algorithm for complex-valued time-frequency T-F masks in single-channel speech enhancement systems. Most speech enhancement algorithms operating in a single-channel microphone environment aim to enhance the magnitude component in a T-F domain, while the input noisy phase component is used directly without any processing. Consequently, the mismatch between the processed magnitude and the unprocessed phase degrades the sound quality. To address this issue, a learning method of targeting a T-F mask that is defined in a complex domain has recently been proposed. However, due to a wide dynamic range and an irregular spectrogram pattern of the complex-valued T-F mask, the learning process is difficult even with a large-scale deep learning network. Moreover, the learning process targeting the T-F mask itself does not directly minimize the distortion in spectra or time domains. In order to address these concerns, we focus on three issues: 1 an effective estimation of complex numbers with a wide dynamic range; 2 a learning method that is directly related to speech enhancement performance; and 3 a way to resolve the mismatch between the estimated magnitude and phase spectra. In this study, we propose objective functions that can solve each of these issues and train the network by minimizing them with a joint learning framework. The evaluation results demonstrate that the proposed learning algorithm achieves significant performance improvement in various objective measures and subjective preference listening test.

A novel detector system for KATRIN to search for keV-scale sterile neutrinos

Sterile neutrinos appear in minimal extensions of the Standard Model of particle physics. If their mass is in the keV regime, they are viable dark matter candidates. One way to search for sterile neutrinos in a laboratory-based experiment is via the analysis of β-decay spectra, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the β-decay spectrum. The objective of the TRISTAN project is to extend the KATRIN setup with a new multi-pixel silicon drift detector system to search for a keV-scale sterile neutrino signal. In this paper we describe the requirements of such a new detector, and present first characterization measurement results obtained with a 7 pixel prototype system.

Monte Carlo simulation of hybrid pixel detectors

Semiconductor sensors are extensively used for X-ray detection, both for spectroscopy and 2D imaging. In this work, the Monte Carlo code PENELOPE v. 2014 with the PenEasy v. 2015 extension was applied for simulating a Medipix3RX detector, including the sensor and the ASIC layers. The code was modified to include the charge dispersion effect modelling at the Pixelated Imaging Detector tally, and validated by investigating the influence of the electric field, incident energy, beam position, pixel size and also by determining the Modulation Transfer Function. The results were compared to experimental data and presented a very good agreement. The Monte Carlo simulation can be used to investigate the detector response and its influence on measured data, such as spatial resolution and X-ray spectra distortion. Besides, the simulation can be applied to determine the energy deposition in each layer of the detector, useful for detection efficiency characterization or radiation damage studies.