Correct Spectrum Research Articles

Dissipation in unsteady turbulence

Recent experiments and simulations have shown that unsteady turbulent flows, before reaching a dynamic equilibrium state, display a universal behaviour. We show that the observed universal non-equilibrium scaling can be explained using a non-equilibrium correction of Kolmogorov's energy spectrum. Given the universality of the experimental and numerical observations, the ideas presented here lay the foundation for the modeling of a wide class of unsteady turbulent flows.

Methods and methodology for FTIR spectral correction of channel spectra and uncertainty, applied to ferrocene

We present methodology for the first FTIR measurements of ferrocene using dilute wax solutions for dispersion and to preserve non-crystallinity; a new method for removal of channel spectra interference for high quality data; and a consistent approach for the robust estimation of a defined uncertainty for advanced structural χr2 analysis and mathematical hypothesis testing. While some of these issues have been investigated previously, the combination of novel approaches gives markedly improved results. Methods for addressing these in the presence of a modest signal and how to quantify the quality of the data irrespective of preprocessing for subsequent hypothesis testing are applied to the FTIR spectra of Ferrocene (Fc) and deuterated ferrocene (dFc, Fc-d10) collected at the THz/Far-IR beam-line of the Australian Synchrotron at operating temperatures of 7K through 353K.

Joint estimation of frequency and direction of arrival under the single-and-parallel spatial-temporal undersampling condition

As the application frequency is increasingly high, it becomes difficult to design joint estimators for the frequencies and directions of arrival (DOAs) under the spatial-temporal undersampling condition. Specifically, on one hand, the temporal Nyquist theorem requires that the sampling rate be at least twice the highest frequency, which is unfordable for the existing analog-to-digital converters; on the other hand, the spatial Nyquist theorem also requires that each inter-element spacing be less than or equal to half the wavelength, which inevitably results in severe mutual coupling among sensors. To solve these intractable problems, in this paper, we propose a joint estimator based on a co-prime sparse array. Firstly, based on the combination of this sparse array and the closed-form robust Chinese remainder theorem (CRT), the theoretical model for the proposed frequency and DOA joint estimator is built up. Secondly, at each sensor, a frequency estimate for the source object can be calculated through implementing the closed-form robust CRT on two frequency remainders, which are generated by applying the Tsui spectrum correction to the discrete Fourier transform results of two receiver sequences. Then, averaging these estimates at all sensors yields the final frequency estimate. Lastly, on the basis of frequency estimation, the final DOA estimate can be calculated through implementing the closed-form robust CRT on all phase-difference remainders, which are also derived from the Tsui spectrum correction. It needs to be emphasized that the proposed joint estimator possesses two attractive merits. One merit is that due to the fact that the proposed array allows a high sparsity of element-spacings, both the hardware cost and the mutual coupling among sensors can be considerably reduced; the other merit is that compared with the existing estimators, the proposed joint estimator achieves high estimation precision even in the single-and-parallel undersampling condition (i.e., multi-time undersampling is bypassed in each sensor element, leading to a high data processing efficiency). In particular, this high accuracy attributes to two aspects:1) the Tsui spectum corrector incorporated in the proposed joint estimator can provide high-accuracy remainders for the CRT recovery; 2) the closed-form robust CRT itself is unbiased and thus the CRT recovery brings no extra system errors. Numerical results verify that the proposed joint estimator possesses both strong noise robustness and high estimation accuracy, which presents a vast potential application in several passive sensing fields such as radar and remote sensing.

Oil-water Two-phase Flow Velocity Measurement Based on Ultrasonic Doppler Spectrum Correction

Oil-water Two-phase Flow Velocity Measurement Based on Ultrasonic Doppler Spectrum Correction

Vision-based measurement system for structural vibration monitoring using non-projection quasi-interferogram fringe density enhanced by spectrum correction method

A non-projection fringe vision measurement system suitable for vibration monitoring was proposed by using the concept of a 2D optical coherence vibration tomography (2D-OCVT) technique. An artificial quasi-interferogram fringe pattern (QIFP), similar to the interferogram of the 2D-OCVT system, was pasted onto the surface of a vibrating structure as a sensor. Image sequences of the QIFP were captured by a high-speed CMOS camera that worked as a detector. It was possible to obtain both the in-plane and out-of-plane vibration simultaneously. The in-plane vibration was obtained by tracking the center of the imaged QIFP using an image cross-correlation method, whilst the out-of-plane vibration was obtained from the changes in period density of the imaged QIFP. The influence of the noise sources from the CMOS image sensor, together with the effect of the imaging distance, the period density of the QIFP and also the key parameters of the fringe density enhanced by the spectrum correction method on the accuracy of the displacement measurement, were investigated by numerical simulations and experiments. Compared with the results from a conventional accelerometer-based measurement system, the proposed method was demonstrated to be an effective and accurate technique for measuring structural vibration without introducing any extra mass from the accelerometer. The significant advantages of this method include its simple installation and real-time dynamic response measurement capability, making the measurement system ideal for the low- and high-frequency vibration monitoring of engineering structures.

Site-Selective and Element-Selective Analysis of Nickel Substituted Li-Rich Layered Material Using By X-Ray Diffraction and Absorption Spectroscopy

1. Introduction Li-rich type (manganese) oxides are one of the most featured cathodes for lithium ion batteries in recent years, owing to their high capacity and cyclability. In these cathodes, partial substitution of manganese by other transition metals such as Ni and Co has been proposed and shown to be effective in improving the performance, [1] however, the role of such metals in the battery performance has not been clarified in detail.We have synthesized Ni ion substituted Li excess manganese oxides (Li2Mn1-xNixO3) as a simple model of Li2MeO3 phase in solid solution cathode to understand the effect of introduced Ni by using the combination of in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction spectroscopy (XDS) analysis. Diffraction anomalous fine structure (DAFS) spectra are achieved by XDS analysis, that there were quantitatively showed potential-dependent transbilayer migration of nickel and manganese and their reversibility. 2. Experimental procedure The active material of nickel substituted Li2MnO3 (Li2Mn1-x NixO3, x = 0 ~ 0.25) was prepared from solid phase calcination at 1173 K for 12 h in air. The working electrode consisted of active material (80 wt.%), acetylene black (10 wt.%) and polyvinylidene difluoride (PVdF) binder (10 wt.%), coated on aluminum current foil.The electrochemical measurements of the electrode were employed using aluminum pouch type cells, metallic lithium as counter and reference electrodes, 1 mol dm-3 LiPF6 in a 3:7 mixture of EC/DMC, and a polyolefin film as a separator. The electrochemical charge and discharge tests were performed at room temperature and the potential range was between 2.0 and 4.8 V.XAS measurements were performed by the three-electrode cell with charging and discharging processes (in Operando). The XAS measurements of the Ni-K and Mn-K edge region were performed using a solid-state detector at beamlines BL28XU in SPring-8 (Hyogo, Japan).The XDS measurements were conducted at beamline BL28XU, SPring-8, Japan. A two-dimensional Pilatus detector (Dectris Co., Ltd.) was mounted onto an arm of a multi-axis goniometer and was used to measure the diffraction profile, and two ionization chamber was used for the absorption correction of the DAFS spectra. 3. Results and Discussion The obtained X-ray absorption near edge structure (XANES) region spectra at N-K energy region of Li2Mn1-x NixO3 (x = 0.25) in the 1st charging and discharging processes are shown in Fig. 1. The edge energy was shifted to high energy, which is suggested that Ni element function as a charge compensation species. However the end of charging region around 4.7 V to 4.8 V was shifted to low energy as seen in previous XAS report [2], which means the reduction of nickel on average in this region.As our group have published before,[3] XANES-like spectra only from selected sites (i.e. DAFS spectra) can be extracted from the XDS analysis. Fig. 2 shows the DAFS spectra of initial sample. The Ni-K edge XANES-like spectra shows that there was cation mixing in the lithium layer of the pristine material. In contrast, Mn-K edge XANES-like spectra shows that manganese mostly occupied in transition metal layer. XDS analysis of the fully charged sample indicated that Ni element further migrated to the lithium layer.These analytical approaches are important to understand the metal migration behavior as a function of operation potential together with the charge compensation mechanism during electrochemical charging and discharging.

Correction of optic spectra on a absorption substrate

Analysis of possibility of determination optical constants of films by numerical and analytical methods is done. It's shown, that universal method of minimization quality function does not get a unique solution. Methods of consistent approximation is proposed to use for determining optical constants. These methods are: correction spectra for absorption in the substrate; correction spectra of films for its absorption; using additional numerical and analytical methods. Method of correction substrate's absorption for determining spectra of films on substrate without absorption is proposed

Quantitative IR microscopy and spectromics open the way to 3D digital pathology.

Currently, only mass-spectrometry (MS) microscopy brings a quantitative analysis of chemical contents of tissue samples in 3D. Here, the reconstruction of a 3D quantitative chemical images of a biological tissue by FTIR spectro-microscopy is reported. An automated curve-fitting method is developed to extract all intense absorption bands constituting IR spectra. This innovation benefits from three critical features: (1) the correction of raw IR spectra to make them quantitatively comparable; (2) the automated and iterative data treatment allowing to transfer the IR-absorption spectrum into a IR-band spectrum; (3) the reconstruction of an 3D IR-band matrix (x, y, z for voxel position and a 4th dimension with all IR-band parameters). Spectromics, which is a new method for exploiting spectral data for tissue metadata reconstruction, is proposed to further translate the related chemical information in 3D, as biochemical and anatomical tissue parameters. An example is given with oxidative stress distribution and the reconstruction of blood vessels in tissues. The requirements of IR microscopy instrumentation to propose 3D digital histology as a clinical routine technology is briefly discussed.

Beyond-mean-field corrections within the second random-phase approximation

A subtraction procedure, introduced to overcome double-counting problems in beyond-mean-field theories, is used in the second random-phase approximation (SRPA). Doublecounting problems arise in the energy-density functional framework in all cases where effective interactions tailored at leading order are used for higher-order calculations, such as those done in the SRPA model. It was recently shown that this subtraction procedure also guarantees that the stability condition related to the Thouless theorem is verified in extended RPA models. We discuss applications of the subtraction procedure, introduced within the SRPA model, to the nucleus 16O. The application of the subtraction procedure leads to: (i) stable results that are weakly cutoff dependent; (ii) a considerable upwards correction of the SRPA spectra (which were systematically shifted downwards by several MeV with respect to RPA spectra, in all previous calculations). With this important implementation of the model, many applications may be foreseen to analyze the genuine impact of 2 particle-2 hole configurations (without any cutoff dependences and anomalous shifts) on the excitation spectra of medium-mass and heavy nuclei.

Determination of isotopic composition of uranium samples using alpha spectrometry

Alpha spectrometry has been employed for the determination of the atom ratios of low enriched uranium samples. WinALPHA was used for the deconvolution and tail correction of the alpha spectra. The atom ratios calculated from alpha spectrometry were compared with that obtained by thermal ionisation mass spectrometry. The results are in good agreement and is encouraging. The tail correction methodology WinALPHA is shown to be applicable for deconvoluting when the alpha activity of high energy peak is more than 45 times the lower energy peaks for obtaining the correct alpha activity ratio which is very challenging and been done for the first time.

Teratogenic study of phenobarbital and levamisole on mouse fetus liver tissue using biospectroscopy

Biospectroscopic investigations have attracted attention of both the clinicians and basic sciences researchers in recent years. Scientists are discovering new areas for FTIR biospectroscopy applications in medicine. The aim of this study was to measure the possibility of FTIR-MSP application for the recognition and detection of fetus abnormalities after exposure of pregnant mouse to phenobarbital (PB) and levamisole (LEV) alone or in combination. PB is one of the most widely used antiepileptic drugs (AEDs), with sedative and hypnotic effects. When used by pregnant women, it is known to be a teratogenic agent. LEV is an antihelminthic drug with some applications in immune-deficiency as well as colon cancer therapy. Four groups of ten pregnant mice were selected for the experiments as follows: one control group received only standard diet, one group was injected with 120mg/kg of BP, one group was injected with 10mg/kg of LEV, and the last group was treated simultaneously with both BP and LEV at the above mentioned doses. Drugs administration was performed on gestation day 9 and fetuses were dissected on pregnancy day 15. Each dissected fetus was fixed, dehydrated and embedded in paraffin. Sections of liver (10μm) were prepared from control and treated groups by microtome and deparaffinized with xylene. The spectra were taken by FTIR-MSP in the region of 4000–400cm−1. All the spectra were normalized based on amide II band (1545cm−1) after baseline correction of the entire spectrum, followed by classification using PCA, ANN and SVM. Both morphological and spectral changes were shown in the treated fetuses as compared to the fetuses in the control group. While cleft palate and C-R elongation were seen in PB injected fetuses, developmental retardation was mostly seen in the LEV injected group. Biospectroscopy revealed that both drugs mainly affected the cellular lipids and proteins, with LEV causing more changes in amide I and lipid regions than PB. Application of PCA, ANN and SVM methods were able to successfully classify these FTIR spectroscopic data and discriminate between control and treated groups of fetuses, making it a new potential tool for drugs teratogenic investigations.

Lasing dynamics study by femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy**Project supported by the National Natural Science Foundation of China (Grant Nos. 20925313 and 21503066), the Innovation Program of Chinese Academy of Sciences (Grant No. KJCX2-YW-W25), the Postdoctoral Project of Hebei University, China, and the Project of Science and Technology Bureau of Baoding City, China (Grant No. 15ZG029).

Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy (FNOPAS) is a versatile technique with advantages of high sensitivity, broad detection bandwidth, and intrinsic spectrum correction function. These advantages should benefit the study of coherent emission, such as measurement of lasing dynamics. In this letter, the FNOPAS was used to trace the lasing process in Rhodamine 6G (R6G) solution and organic semiconductor nano-wires. High-quality transient emission spectra and lasing dynamic traces were acquired, which demonstrates the applicability of FNOPAS in the study of lasing dynamics. Our work extends the application scope of the FNOPAS technique.

Enhancement of low-quality reconstructed digital hologram images based on frequency extrapolation of large objects under the diffraction limit

During the reconstruction of a digital hologram, the reconstructed image is usually degraded by speckle noise, which makes it hard to observe the original object pattern. In this paper, a new reconstructed image enhancement method is proposed, which first reduces the speckle noise using an adaptive Gaussian filter, then calculates the high frequencies that belong to the object pattern based on a frequency extrapolation strategy. The proposed frequency extrapolation first calculates the frequency spectrum of the Fourier-filtered image, which is originally reconstructed from the +1 order of the hologram, and then gives the initial parameters for an iterative solution. The analytic iteration is implemented by continuous gradient threshold convergence to estimate the image level and vertical gradient information. The predicted spectrum is acquired through the analytical iteration of the original spectrum and gradient spectrum analysis. Finally, the reconstructed spectrum of the restoration image is acquired from the synthetic correction of the original spectrum using the predicted gradient spectrum. We conducted our experiment very close to the diffraction limit and used low-quality equipment to prove the feasibility of our method. Detailed analysis and figure demonstrations are presented in the paper.

Quantitative evaluation on the performance and feature enhancement of stochastic resonance for bearing fault diagnosis

Stochastic resonance (SR) has been widely applied in the field of weak signal detection by virtue of its characteristic of utilizing noise to amplify useful signal instead of eliminating noise in nonlinear dynamical systems. How to quantitatively evaluate the performance of SR, including the enhancement effect and the degree of waveform distortion, and how to accurately extract signal amplitude have become two important issues in the research on SR. In this paper, the signal-to-noise ratio (SNR) of the main component to the residual in the SR output is constructed to quantitatively measure the enhancement effect of the SR method. And two indices are constructed to quantitatively measure the degree of waveform distortion of the SR output, including the correlation coefficient between the main component in the SR output and the original signal, and the zero-crossing ratio. These quantitative indices are combined to provide a comprehensive quantitative index for adaptive parameter selection of the SR method, and eventually the adaptive SR method can be effective in enhancing the weak component hidden in the original signal. Fast Fourier Transform and Fourier Transform (FFT+FT) spectrum correction technology can extract the signal amplitude from the original signal and effectively reduce the difficulty of extracting signal amplitude from the distorted resonance output. The application in vibration analysis for bearing fault diagnosis verifies that the proposed quantitative evaluation method for adaptive SR can effectively detect weak fault feature of the vibration signal during the incipient stage of bearing fault.

Breaking CMB degeneracy in dark energy through LSS

The cosmic microwave background and large scale structure are complementary probes to investigate the early and late time universe. After the current accomplishment of the high accuracies of CMB measurements, accompanying precision cosmology from LSS data is emphasized. We investigate the dynamical dark energy models which can produce the same CMB angular power spectra as that of the LCDM model with less than a sub-percent level accuracy. If one adopts the dynamical DE models using the so-called Chevallier-Polarski-Linder (CPL) parametrization, w = w0 + wa(1-a), then one obtains models (w0,wa)= (-0.8,-0.767), (-0.9,-0.375), (-1.1,0.355), (-1.2,0.688) named as M8, M9, M11, and M12, respectively. The differences of the growth rate, f which is related to the redshift space distortions (RSD) between different DE models and the LCDM model are about 0.2% only at z=0. The difference of f between M8 (M9, M11, M12) and the LCDM model becomes maximum at z ~ 0.25 with -2.4 (-1.2, 1.2, 2.5)%. This is a scale-independent quantity. One can investigate the one-loop correction of the matter power spectrum of each model using the standard perturbation theory in order to probe the scale-dependent quantity in the quasi-linear regime ({\it i.e.} k < 0.4 h/Mpc). The differences in the matter power spectra including the one-loop correction between M8 (M9, M11, M12) and the LCDM model for k= 0.4 h/Mpc scale are 1.8 (0.9, 1.2, 3.0)% at z=0, 3.0 (1.6, 1.9, 4.2)% at z=0.5, and 3.2 (1.7, 2.0, 4.5)% at z=1.0. The bigger departure from -1 of w0, the larger the difference in the power spectrum. Thus, one should use both the RSD and the quasi-linear observable in order to discriminate a viable DE model among a slew of models which are degenerated in CMB. Also we obtain the lower limit on w0 > -1.5 from the CMB acoustic peaks and this will provide the useful limitation on phantom models.

Expanding Lorentz and spectrum corrections to large volumes of reciprocal space for single-crystal time-of-flight neutron diffraction.

Evidence is mounting that potentially exploitable properties of technologically and chemically interesting crystalline materials are often attributable to local structure effects, which can be observed as modulated diffuse scattering (mDS) next to Bragg diffraction (BD). BD forms a regular sparse grid of intense discrete points in reciprocal space. Traditionally, the intensity of each Bragg peak is extracted by integration of each individual reflection first, followed by application of the required corrections. In contrast, mDS is weak and covers expansive volumes of reciprocal space close to, or between, Bragg reflections. For a representative measurement of the diffuse scattering, multiple sample orientations are generally required, where many points in reciprocal space are measured multiple times and the resulting data are combined. The common post-integration data reduction method is not optimal with regard to counting statistics. A general and inclusive data processing method is needed. In this contribution, a comprehensive data analysis approach is introduced to correct and merge the full volume of scattering data in a single step, while correctly accounting for the statistical weight of the individual measurements. Development of this new approach required the exploration of a data treatment and correction protocol that includes the entire collected reciprocal space volume, using neutron time-of-flight or wavelength-resolved data collected at TOPAZ at the Spallation Neutron Source at Oak Ridge National Laboratory.

Spectrum Correction in Study of Solvation Dynamics by Fluorescence Non-collinear Optical Parametric Amplification Spectroscopy

Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy can extract the curve of spectral gain from its parametric superfluorescence. This unique spectrum correction method enables fluorescence non-collinear optical parametric amplification spectroscopy acquiring the genuine transient fluorescence spectrum of the studied system. In this work we employ fluorescence non-collinear optical parametric amplification spectroscopy technique to study the solvation dynamics of DCM dye in ethanol solution, and confirm that genuine solvation correlation function and shift of peak frequency can be derived from transient fluorescence spectra after the spectral gain correction. It demonstrates that fluorescence non-collinear optical parametric amplification spectroscopy can benefit the research fields, which focuses on both fluorescence intensity dynamics and fluorescence spectral shape evolution.

NMR-based metabonomics for understanding the influence of dormant female genital tuberculosis on metabolism of the human endometrium.

Does investigation of metabolic perturbations in endometrial tissue of women with dormant genital tuberculosis (GTB) during the window of implantation (WOI) assist in improving the understanding of endometrial receptivity? In dormant GTB cases significant alterations in endometrial tissue metabolites occur, largely related to energy metabolism and amino acid biosynthesis in dormant GTB cases. As an intracellular pathogen, Mycobacterium tuberculosis strongly influences the metabolism of host cells causing metabolic dysregulation. It is also accepted that dormant GTB impairs the receptive status of the endometrium. Global metabolic profiling is useful for an understanding of disease progression and distinguishing between diseased and non-diseased groups. Endometrial tissue samples were collected from patients reporting at the tertiary infertility care center during the period September 2011-March 2013. Women having tested positive for GTB were considered as the study group (n = 24). Normal healthy women undergoing sterilization (n = 26) and unexplained infertile women with repeated IVF failure (n = 21) volunteered to participate as controls. Endometrial tissue samples were collected 6-10 days after confirmation of ovulation. PCR and BACTEC-460 culture were used for diagnosing GTB. Proton nuclear magnetic resonance (1H NMR) spectra of tissue were recorded using a 700 MHz Bruker Avance AV III spectrometer. Following phase and baseline correction of all NMR spectra by Bruker Topspin 2.1 software, spectral peak alignment of the data was performed. Multivariate analysis was applied to all spectra and individual metabolites identified and multiple correlation analysis was performed. Leucine, isoleucine, acetate, lactate, glutamate, glutamine, methionine, lysine, creatine, glycogen, glycine, proline and choline were found to be significantly increased (P < 0.05) in endometrial tissue of women with dormant GTB compared with unexplained infertile women with repeated implantation failure. Valine, citrate, succinate and aspartate were also observed to be significantly up-regulated (P < 0.01). Furthermore, a significant decrease in glucose (P < 0.05), threonine (P < 0.05), tyrosine (P < 0.01) and phenylalanine (P < 0.0001) was observed in women with dormant GTB. Pearson's correlation analysis between the expression of various endometrial receptivity markers and metabolites showed a significant negative correlation (-0.236 to -0.545, P < 0.05). Also, the metabolites were positively correlated with endometrial receptivity markers (0.207 to 0.618, P < 0.05). It is often difficult to diagnose dormant GTB because it tends to exist without any clinical signs or symptoms. In addition, the diagnosis of GTB by culture remains a challenge due to low detection rates and its paucibacillary nature. Testing for prostate-specific antigen or the Y chromosome in order to account for the possible influences of recent exposure to semen on endometrial metabolism would be important. The metabolic changes associated with the dormant tubercle infection are of potential relevance to clinicians for the treatment of dormant GTB-related infertility. Government of India, Indian Council of Medical Research. There are no conflicts of interest.

Can DSGE Models Explain Real Exchange Rate Facts at All Frequencies

This paper evaluates the ability of a standard IRBC model augmented with input adjustment cost of imported good, in explaining dierent aspects of real exchange rate like the standard deviation, the autocorrelation function, the spectrum and integral correction mechanism. I find that the simple IRBC model with appropriate calibration can well capture all the features of real exchange rate. The input adjustment cost plays the key role. Comparing to the standard model, it implies a reversed impulse response of real exchange rate with a fast speed going back to steady state and introduces a long run cyclical movement in most macroeconomic variables. I find this particular impulse response helps explain the PPP puzzle.

A spectrophotometric method for determination of the optical constants of materials

We propose a method for determining the optical constants of materials used in transmission optics. This technique is based on correction of absorption spectra. The absorption A may be divided into two parts: AT describes the contribution of absorption to the transmission spectrum, and AR describes the contribution of absorption to the reflection spectrum. The AT and AR spectra used to correct the RT spectra were calculated using correction functions and the total absorption A. Correction removes absorption from the spectra, so that the existing methods for determining the refractive index n can be used. We obtain analytical expressions for the absorption coefficient α and assess the accuracy of the method; this assessment indicated that spectral correction enables n to be determined to a maximum accuracy of 0.0001. The method was tested on optical silicon near the 9-μm absorption band.