Total Scatter Research Articles

Average and local structure analysis of Na/Li ion-exchanged Lix(Mn,Ni,Ti)O2 using synchrotron X-ray and neutron sources

Mn-rich layered Lix(Mn,Ni,Ti)O2 was synthesized by Na/Li ion exchange of a P3-Na0.7(Mn,Ni,Ti)O2 precursor. The combined chemical analysis with the ICP-AES, titration technique, and XANES indicated that their electroneutralities were satisfied in some vacancies of the transition metals (TMs). Average structure analyzed using synchrotron X-ray and neutron powder diffraction patterns confirmed a significant amount of vacancies at TM sites and further revealed the existence of a minor tetrahedral Li in the layered rock-salt type Lix(Mn,Ni,Ti)O2. Electrochemical properties of Li0.6Na0.02Mn0.71Ni0.13Ti0.12□0.04O2 exhibited high first discharge capacity of ca. 250 mAh g−1 and high cyclability of exceeding 200 mAh g−1 at the 50th cycle. PDF analysis achieved good fittings for the both total scatterings of synchrotron X-ray and neutron with additional tetrahedral Li and some TM vacancies. Each (Mn,Ni,Co)O6 octahedron in the refined local structure was calculated and expressed as 3D distributions, where the NiO6 and the host MnO6 octahedra were visually characterized as significantly less distorted and highly distorted octahedra, respectively. The co-substitution of Ni2+ ant Ti4+ played the role of stabilizing whole structure and preserving the transition metal vacancy to maintain the high capacity during cycles.

Investigations on the gamma-ray shielding performance of green concrete using theoretical, experimental and simulation techniques

A newly developed concrete obtained by partially replacing Ordinary Portland Cement (OPC) by Bismuth-Ground Granulated Blast Furnace Slag (Bi-GGBFS) have been analysed for its gamma-ray shielding behaviour (GSB). The experimental measurements were performed by using narrow beam gamma transmission geometry with scintillation detector, NaI(Tl) 2 ʺ × 2 ʺ, MCA, and point isotropic sources 241Am, 137Cs and 60Co. For the measurements of incident and transmitted gamma photon intensities the value of total scatter acceptance angle (θsc) was 2.13°. These experimentally measured values of linear attenuation coefficient are further used to calculate the values of mean free path (mfp), half value layer (HVL), mass attenuation coefficient (MACμm), effective atomic number (Zeff), electron density (Ne),exposure build up factor (EBF), Klein-Nishina electronic (σeKN), electron transfer (σetr), atomic cross-section σaKN and Compton MACs. The experimental values of mass attenuation coefficient (MACμm) have been compared with the results of FLUKA simulations and theoretical values obtained by using WinXCOM computer software. Excellent agreements have been observed between experimental, theoretical and simulation values of MAC. It has been concluded that Bi-GGBFS concrete offers better GSB that other concretes such as ordinary-concrete, diaspore-flyash concrete, and lead fly-ash concrete.

Single-phase synthesis, average, electronic, and local structure and cathode properties of pyroxene type LiFeSi2O6

Single-phase LiFeSi2O6 with pyroxene structure was firstly synthesized via a hydrothermal route under specific conditions with optimal water amount. Using both synchrotron X-ray and neutron diffraction techniques, crystal structure refinement with the C2/c space group resulted in well converged anisotropic displacement parameters. The electron density distributions were calculated by the maximum-entropy method (MEM) and showed the difference in the Si-O bond before and after charging. A carbon composite with LiFeSi2O6 exhibited strongly enhanced electrochemical properties as the cathode for Li-ion batteries due to the improved electronic conductivity. The X-ray absorption near edge structure (XANES) spectra revealed the redox of iron was not involved in the charge and discharge processes, while other mechanisms for charge and discharge were predicted to be related to Si or O. The local structure was refined by pair distribution function (PDF) analysis of the synchrotron X-ray and neutron total scatterings, which indicated Li-ion diffusion as a one-dimensional path.

A forecasting model for wave heights based on a long short-term memory neural network

To explore new operational forecasting methods of waves, a forecasting model for wave heights at three stations in the Bohai Sea has been developed. This model is based on long short-term memory (LSTM) neural network with sea surface wind and wave heights as training samples. The prediction performance of the model is evaluated, and the error analysis shows that when using the same set of numerically predicted sea surface wind as input, the prediction error produced by the proposed LSTM model at Sta. N01 is 20%, 18% and 23% lower than the conventional numerical wave models in terms of the total root mean square error (RMSE), scatter index (SI) and mean absolute error (MAE), respectively. Particularly, for significant wave height in the range of 3–5 m, the prediction accuracy of the LSTM model is improved the most remarkably, with RMSE, SI and MAE all decreasing by 24%. It is also evident that the numbers of hidden neurons, the numbers of buoys used and the time length of training samples all have impact on the prediction accuracy. However, the prediction does not necessary improve with the increase of number of hidden neurons or number of buoys used. The experiment trained by data with the longest time length is found to perform the best overall compared to other experiments with a shorter time length for training. Overall, long short-term memory neural network was proved to be a very promising method for future development and applications in wave forecasting.

Commissioning and quality assurance of Euromechanics add-on multileaf collimator

In this study, the beam characteristics of a Euromechanics add-on MLC that has been installed on a Varian CLINAC 2100 C/D linear accelerator are presented. This was the first installation of 60-leaf PMLC from Euromechanics Company worldwide and all mechanical and dosimetric parameters were measured before clinical use of this kind of MLC. Mechanical tests were executed for different gantry and collimator angles. Leaf position accuracy and leaf gap reproducibility were checked with four different tests. The leaf transmissions, collimator (Sc), phantom (Sp), total (Sc,p) scatter factors, output of the machine, beam profiles for off-axis ratios, central axis depth dose, flatness, symmetry and penumbra have been measured for different field sizes pre and post MLC installation in 6 and 18 MV-mode. To evaluate the effect of new data on clinical plans, different beam setup configurations conformed with MLC and custom blocks were planned on CT images of thorax a CIRS phantom model 002LFC in the same treatment planning system. Leaf position in picket fence test found to be in range between 4.89–5.02 cm instead of nominal 5 cm, however the results of this test with EPIDs image and PIPSpro software showed the higher deviation rather than the results reported from the tests with EBT3 films. The measured data showed that on average Sc,p and Sc were increased 0.22% (P = 0.86) and 0.34% (P = 0.86) for 6 MV and 0.37% (P = 0.84) and 0.42% (P = 0.88) for 18 MV beams for different field sizes, respectively. Good agreement was observed between the PDD and profile curves pre and post MLC installation that was expected based on no changes in beam energy and geometry of the collimators. Based on the mechanical and dosimetry results which have been achieved from our different standard tests, it was found no significant differences between pre and post MLC installation values. This indicates, installation and using this system is clinically acceptable.

Atmospheric pressure loading in GPS positions: dependency on GPS processing methods and effect on assessment of seasonal deformation in the contiguous USA and Alaska

The Global Positioning System (GPS) has revolutionized the ability to monitor Earth-system processes, including Earth’s water cycle. Several analysis centers process GPS data to estimate ground-antenna positions at daily temporal resolution. Differences in processing strategies can lead to inconsistencies in coordinate-position estimates and therefore influence the analysis of crustal displacement associated with variations in atmospheric and hydrologic mass loading. Here, we compare five GPS data products produced by three processing centers: the Nevada Geodetic Laboratory, Jet Propulsion Laboratory, and UNAVCO Consortium. We find that 5 to 30% of the scatter in residual GPS time series (commonly considered noise) can be explained by atmospheric loading in the contiguous USA and Alaska, but that the percentages vary widely by data product. Positions derived using high-resolution troposphere models (e.g., ECMWF) exhibit significantly lower scatter after correcting for atmospheric loading than positions estimated using constant or slowly varying troposphere models (e.g., GPT2w). The data products also exhibit differences in seasonal deformation (commonly attributed, in large part, to fluctuations in hydrologic mass loading): median vector differences in estimated seasonal amplitude range from 0.4–1.0 mm in the vertical component and 0.1–0.3 mm in the horizontal components, or about 10–40% of the mean amplitudes of seasonal oscillation. Newer products exhibit lower total scatter and stronger correlations than older products. Network-coherent differences in estimates of seasonal deformation reveal reference-frame inconsistencies between data products. We also cross-check two independent models of atmospheric pressure loading: ESMGFZ and LoadDef.

Gallery-sensitive single sample face recognition based on domain adaptation

Taking advantage of labeled auxiliary training data whose distribution is similar to the distribution of the gallery, single sample face recognition (SSFR) has achieved encouraging performance. However, in many real-world applications, it is difficult to collect such an auxiliary training dataset, while it may be easier to collect an unlabeled target training dataset whose distribution is similar to the distribution of the gallery and a labeled source training dataset whose distribution may be different to the distribution of the gallery. How can these three datasets be effectively leveraged to handle SSFR? To address this issue, this paper proposes a new method of Gallery-Sensitive Single Sample Face Recognition based on Domain Adaptation (GS-DA). First, GS-DA employs the method of TSD (targetize the source domain) to construct a common subspace and a targetized source domain. Secondly, it projects each gallery image into the common subspace and obtains the sparse representation of each gallery image in the common subspace. Thirdly, it reconstructs each gallery image from the targetized source domain to estimate the within-class scatter matrix and the between-class scatter matrix of the gallery. Lastly, it learns a discriminant model by maximizing the sum of the traces of the between-class scatter matrix of the gallery and the between-class scatter matrix of the targetized source domain as well as minimizing the sum of the traces of the total scatter matrix of the gallery and the total scatter matrix of the target training data. The experimental results on five datasets illustrate the superiority of GS-DA in leveraging these three datasets for SSFR.

WISDOM project – VI. Exploring the relation between supermassive black hole mass and galaxy rotation with molecular gas

ABSTRACT Empirical correlations between the masses of supermassive black holes (SMBHs) and properties of their host galaxies are well established. Among these is the correlation with the flat rotation velocity of each galaxy measured either at a large radius in its rotation curve or via a spatially integrated emission-line width. We propose here the use of the deprojected integrated CO emission-line width as an alternative tracer of this rotation velocity, which has already been shown useful for the Tully–Fisher (luminosity–rotation velocity) relation. We investigate the correlation between CO line widths and SMBH masses for two samples of galaxies with dynamical SMBH mass measurements, with spatially resolved and unresolved CO observations, respectively. The tightest correlation is found using the resolved sample of 25 galaxies as $\log (M_\mathrm{BH}/\mathrm{M_\odot })=(7.5\pm 0.1)+(8.5\pm 0.9)[\log (W_\mathrm{50}/\sin i \, \mathrm{km\, s}^{-1})-2.7]$, where MBH is the central SMBH mass, W50 is the full width at half-maximum of a double-horned emission-line profile, and i is the inclination of the CO disc. This relation has a total scatter of $0.6\,$ dex, comparable to those of other SMBH mass correlations, and dominated by the intrinsic scatter of $0.5\,$ dex. A tight correlation is also found between the deprojected CO line widths and the stellar velocity dispersions averaged within one effective radius. We apply our correlation to the COLD GASS sample to estimate the local SMBH mass function.

Robust Two-Dimensional Linear Discriminant Analysis via Information Divergence

Due to the complexities of collected data that may contain outliers and noises, many variants of LDA and 2DLDA have been proposed to address this problem and have shown that the improved methods produce much better performance than classical LDA and 2DLDA. In this paper we propose a novel two-dimensional linear discriminant analysis method via information divergence. The proposed method applies the weighted L21 norm to learn a robust projection matrix in the image space. In the proposed model, we introduce the weights into the within-class scatter and the total scatter simultaneously, and learn the weights by imposing information divergence on the objective functions. To handle the proposed model, we resort to Dinkelbach’s extended algorithm to solve the proposed ratio minimization problem. Considering the characteristics of the subproblems, we exploit an equivalent representation of subproblems which can be solved by alternating optimization techniques where each block of variables has good optimization properties. The proposed model not only overcomes the small-sample-size problem, but also suppresses outliers by an adaptively weighted scheme with the guidance of information divergences. The experiments on several image data sets demonstrate that the classification performance of the proposed method is superior to that of some existing methods in the presence of outliers.

Local structured feature learning with dynamic maximum entropy graph

In recent years, Linear Discriminant Analysis (LDA) has seen huge adoption in data mining applications. Due to its globality, it is incompetent to handle multimodal data. Besides, most of LDA’s variants learn the projection matrix based on the pre-defined similarity matrix, which is easily affected by noisy and irrelevant features. To address above two issues, a novel local structured feature learning with Dynamic Maximum Entropy Graph (DMEG) method is developed which firstly develops a more discriminative LDA with whitening constraint that can minimize the within-class scatter while keeping the total samples scatter unchanged simultaneously. Second, for exploring the local structure of data, the ℓ0-norm constraint is imposed on similarity matrix to ensure the k connectivity on graph. More importantly, proposed model learns the similarity and projection matrix simultaneously to ensure that the neighborships can be found in the optimal subspace where the noise have been removed already. Moreover, a maximum entropy regularization is employed to reinforce the discriminability of graph and avoid the trivial solution. Last but not least, an efficient iterative optimization algorithm is provided to optimize proposed model with a NP-hard constraint. Extensive experiments conducted on synthetic and several real-world data sets demonstrate the efficiency in classification task and robustness to noise of proposed method.

Structural Disorder of Mechanically Activated δ-MgCl2 Studied by Synchrotron X-ray Total Scattering and Vibrational Spectroscopy

A combination of synchrotron X-ray total scattering and molecular simulation is a powerful approach for reliable determination of the structure of δ-MgCl2 as an indispensable component of heterogeneous Ziegler–Natta catalysts. Here, the same approach is applied to mechanically activated MgCl2. Four types of mechanically activated MgCl2 samples are prepared using ball-milling in the absence and presence of different donors. The development of structural disorder along the grinding time is compared. It was found that the presence of donors accelerates the formation of δ-MgCl2 in an early stage of grinding, while elongated grinding eventually results in δ-MgCl2 with similar extents of structural disorder in the absence and presence of different donors. The FT-IR investigation consistently verified the morphological similarity between the firmly ground samples. Thus, the structure of δ-MgCl2 is likely governed by mechanical energy when sufficiently ground.

Scattering and absorption invariance of nonmagnetic particles under duality transformations

We revisit the total scatterings (in terms of extinction, scattering, and absorption cross sections) by arbitrary clusters of nonmagnetic particles that support optically induced magnetic responses. Our reexamination is conducted from the perspective of the electromagnetic duality symmetry, and it is revealed that all total scattering properties are invariant under duality transformations. This secures that, for self-dual particle clusters, the total scattering properties are polarization independent for any fixed incident direction, while, for non-self-dual particle clusters, two scattering configurations that are connected to each other through a duality transformation would exhibit identical scattering properties. This electromagnetic duality induced invariance is irrelevant to specific particle distributions or wave incident directions, which is illustrated for both random and periodic clusters.

ИССЛЕДОВАНИЕ СОГЛАСОВАННОСТИ ЭКСПЕРТНЫХ ОЦЕНОК ПРИ ЗАВИСИМЫХ ВЫБОРКАХ

The problem of the agreement in experts’ opinions is one of the main ones in making collective decisions. The quality of the collective decision (accuracy, reliability, reliability, number of experts, time and laboriousness of decision making) depends on the degree of consistency of expert decisions. The article discusses the issues of reliability of estimates given by a group of experts for dependent samples. The dependence of random variables in samples is manifested, first of all, in testing systems. The dependence can be between the test questions, as well as between the student’s answers to the test questions on different topics. A connection can also be found between the answers of different trainees with a similar assimilation of the educational material. In the article, to determine the consistency of expert assessments, the indicator is the sum of centered values of random variables corresponding to the assigned estimates. This indicator characterizes the total scatter of expert assessments relative to the arithmetic mean of the collective assessment. In case of complete agreement of opinions, the value of the indicator is zero. The characteristics of the scatter of estimates are derived from the Chebyshev theorem. The lower and upper bounds of the estimation error are obtained. The confidence interval for the correlation coefficient is built. A formula for finding the proportion of possible deviations in the score is derived. The behavior of the boundaries of the confidence interval was investigated for different values of the point estimate. The case is considered when all correlation coefficients are non-negative. A comparison is made of the behavior of the boundaries of the confidence intervals for non-negative correlation coefficients and the general case. The results obtained can be used, for example, in testing systems for personnel training, in product quality control systems, to select promising technologies, and medical diagnostics.

The role of nanoparticle structure and morphology in the dissolution kinetics and nutrient release of nitrate-doped calcium phosphate nanofertilizers

Bio-inspired synthetic calcium phosphate (CaP) nanoparticles (NPs), mimicking the mineral component of bone and teeth, are emergent materials for sustainable applications in agriculture. These sparingly soluble salts show self-inhibiting dissolution processes in undersaturated aqueous media, the control at the molecular and nanoscale levels of which is not fully elucidated. Understanding the mechanisms of particle dissolution is highly relevant to the efficient delivery of macronutrients to the plants and crucial for developing a valuable synthesis-by-design approach. It has also implications in bone (de)mineralization processes. Herein, we shed light on the role of size, morphology and crystallinity in the dissolution behaviour of CaP NPs and on their nitrate doping for potential use as (P,N)-nanofertilizers. Spherical fully amorphous NPs and apatite-amorphous nanoplatelets (NPLs) in a core-crown arrangement are studied by combining forefront Small-Angle and Wide-Angle X-ray Total Scattering (SAXS and WAXTS) analyses. Ca2+ ion release rates differ for spherical NPs and NPLs demonstrating that morphology plays an active role in directing the dissolution kinetics. Amorphous NPs manifest a rapid loss of nitrates governed by surface-chemistry. NPLs show much slower release, paralleling that of Ca2+ ions, that supports both detectable nitrate incorporation in the apatite structure and dissolution from the core basal faces.

X‐Ray Total Scattering of Electrolytes in Liquid‐Based Fluoride Shuttle Battery: Electrolyte Composition Dependence of the Low‐Q Peak

X‐ray total scattering is applied to a series of molecular liquids including the CsF salt, which is expected to be a promising electrolyte in fluoride shuttle batteries. These electrolytes are composed of solvent molecules and addition agents (AAs), together with CsF. Tetraglyme (G4) or γ‐butyrolactone (GBL) is used as a solvent molecule, and lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), triphenylboroxine (TPhBX), or lithium bis(oxaloto)borate (LiBOB) as an AA. It is found that an additional peak appears on the low‐Q side of the main peak by the addition of LiFSI, LiTFSI, or TPhBX to the solvent, which indicates that correlation between cation and anion molecules is induced by these AAs. Furthermore, the position and the intensity of this peak are changed by the addition of the CsF salt, suggesting the modification of the correlation in the presence of the Cs+ and F− ions.

Fast-current-heating devices to study in situ phase formation in metallic glasses by using high-energy synchrotron radiation.

Details of fast-resistive-heating setups, controlled heating ranging from ∼101 K s-1 to ∼103 K s-1, to study in situ phase transformations (on heating and on cooling) in metallic glasses by high-energy synchrotron x-ray diffraction are discussed. Both setups were designed and custom built at the Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) and have been implemented at the P02.1 Powder Diffraction and Total Scattering Beamline and the P21.1 Swedish Materials Science Beamline at PETRA III storage ring, DESY, Hamburg. The devices are interchangeable at both beamlines. Joule heating is triggered automatically and is timed with the incident beam and detector. The crystallization process can be controlled via a feedback circuit by monitoring the change in the time-dependent resistivity and temperature of glasses. Different ambient atmospheres, such as vacuum and inert gases (He and Ar), can be used to control oxidation and cooling. The main focus of these devices is on understanding the crystallization mechanism and kinetics in metallic glasses, which are brittle and for which fast heating gives defined glass-crystal composites with enhanced plasticity. As an example, phase-transformation sequence(s) in a prototyped Cu-Zr-based metallic glass is described on heating, and a crystalline phase beneficial to the plasticity is identified.

Short-term effects of meteorological factors, air pollution, and sunspot on childhood hand, foot, and mouth disease in Tianjin, China: a new time series regression, 2014-2018.

This study is aimed at defining the relationship between a set of environmental factors and childhood HFMD and then at estimating the related effect. The 16 environmental factors included meteorological, air pollution, and sunspot. A traditional TSR modified by using susceptible-infectious-recovery models and distribution lag nonlinear model was applied to estimate the short-term effects of daily environmental factors on children HFMD occurrence in 2014–2018 with adjustment of potential confounding factors. A total of 70,027 children aged 0–15 years with HFMD were enrolled. No significant effect was observed for daily sunspot numbers and average visibility. We found positive effects of the ambient average temperature, with an approximately m-shaped curve of the overall cumulative relationship, peaking at 25.6 °C with a relative risk (RR) of 1.45 (95% confidence intervals 1.21–1.73). The largest RR value of hot effect was achieved on the current day and then decreased by 2 days (total group, male group, and scatter group) or 1 day (female group and nursery group), and the effect lasted about 6 to 8 days from the lag 4 or lag 6 day. A greater association of temperature with HFMD for the female group and the scattered group was observed. This study suggests that ambient average temperature might be a risk factor for children HFMD in Tianjin. Further studies are warranted to confirm these findings.

Why Does Bi2WO6 Visible-Light Photocatalyst Always Form as Nanoplatelets?

Bi2WO6 nanocrystals exhibit excellent photocatalytic properties in the visible range of the solar spectrum, and intense efforts are directed at designing effective synthesis processes with control of size, morphology, and hierarchical structure. All known hydrothermal syntheses produce either nanoplatelet morphology or hierarchical structures based on such primary entities. Here we investigate the nucleation and growth of Bi2WO6 nanocrystals under hydrothermal conditions using in situ X-ray total scattering (TS) and powder X-ray diffraction (PXRD) measurements. It is shown that the preferential growth of Bi2WO6 nanoplates is due to the presence of disordered layers of Bi2O22+ molecular complexes in the precursor solution with an approximate length of 13 Å. These layers interact with tetrahedral WO42- molecular units and eventually form the disordered cubic (Bi0.933W0.067)O1.6) crystalline phase. When enough tungsten units are intertwined between Bi2O22+ layers formation of Bi2WO6 pristine nanoplates takes place by necessary sideways addition of units in the ac plane. The experimentally observed formation mechanism suggests that the Bi/W atomic ratio must play a central role in the nucleation (assembly of initial crystal layers). Indeed, it is observed in separate continuous flow supercritical synthesis that for a stoichiometric (Bi/W = 2:1) precursor, a (Bi0.933W0.067)O1.6) impurity phase is always observed together with the main Bi2WO6 product. Excess tungsten is required in the precursor to form phase-pure Bi2WO6 material. Thus, the present study also reports a fast, scalable, and green method for production of this highly attractive photocatalyst.

Structural Variation in Carbonate Electrolytes by the Addition of Li Salts Studied by X‐Ray Total Scattering

X‐ray total scattering measurements are carried out for the typical electrolyte used in lithium‐ion batteries, that is, the mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) electrolyte with LiPF6 salt. The obtained pair distribution function is compared with that of the EC/EMC solvent without LiPF6, to investigate the effect of the Li+ cation on the intramolecular structure. It is found that the peak shift corresponding to the shrinking of the CO bonds is induced by dissolving LiPF6. Also, the peak height becomes lower by the addition of LiPF6. These behaviors are also observed by the X‐ray total scattering measurements for the mixture of EC and dimethyl carbonate (DMC) with and without LiPF6. Also, it is ascertained that such a shrinking is present in EC/DMC electrolytes by means of neutron total scattering. First‐principles calculations on the basis of the density functional theory for isolated EC, EMC, and DMC molecules with the Li+ cation confirm that the shrinking of the CO bond is accompanied by the formation of the solvation structure. The observed structural variations induced by adding LiPF6 will be a good indicator for the formation of the solvation structure.

3d Most-Probable All-Atom Structure of Atactic Polystyrene During Glass Formation: A Neutron Total Scattering Study

The deepest and most interesting unsolved problem in soft condensed matter physics is the nature of glass formation, and one of the most difficult things to solve the problem is to directly observe...