Real Polarization Research Articles

Sentiment classification within online social media using whale optimization algorithm and social impact theory based optimization

In recent years, social networks have become an important part of daily life and are becoming increasingly important. In this study, sentiment analysis or opinion mining, which is one of the most well-known social network analysis problems, is considered as an optimization problem for the first time. In the same way, for the first time, sentiment analysis is considered as a multi-objective problem. Whale Optimization Algorithm and Social Impact Theory based Optimization Algorithm, which are the current intelligent optimization algorithms, are adapted for the sentiment analysis problem. Furthermore, memory feature is integrated into Social Impact Theory based Optimization Algorithm in order to obtain effective results in this study. The obtained results from the proposed algorithms are also compared with thirty-three supervised learning algorithms within real IMDB, Polarity, and Amazon data sets. In order to evaluate the performance of the results; accuracy percentage, precision, recall, F-Measure, and MCC that are the five most commonly used measure in the literature are used. When the results are examined, it is observed that adapted metaheuristic optimization algorithms give more successful results in sentiment analysis problem.

Non-ideal modelling of polymeric hollow-fibre membrane systems: Pre-combustion CO2 capture case study

Some membrane gas separation applications operate at high temperature and pressure. However, the majority of membrane gas separation models employ simplifying assumptions which are not realistic under these conditions. In this study, a rigorous model is developed for polymeric hollow-fibre membrane modules incorporating non-isothermal separation (the Joule-Thomson effect), real gas behavior and concentration polarization. The model also accounts for temperature-dependent permeability, friction-based pressure loss on both feed and permeate sides and variable physical and transport properties. The rigorous model is applied for pre-combustion CO2 capture, i.e. CO2/H2 separation, and compared with a simplistic model for various polymeric membranes through changing temperature-independent activation energy of permeation and pre-exponential factor. Two types of H2- and CO2-selective membranes are then chosen for further analysis. As feed conditions change, the deviation between the rigorous and simplistic models ranges approximately from 2 to 12% for stage-cut and 2–20% for the permeate composition. The difference is mostly because of real gas behavior at low stage-cuts, while the Joule-Thomson effect adds to this behavior at high stage-cuts (≥40%) resulting in the greater deviation. The influence of concentration polarization, however, is found negligible even at high stage-cuts.

Anodic Polarization Behavior of X80 Steel in Na₂SO₄ Solution under High Potential and Current Density Conditions.

X80 steel has great risk of corrosion in high voltage direct current (HVDC) interference cases. In this study, the anodic polarization behavior of X80 steel under high potential and current density in Na2SO4 solution was investigated. The I × R drop was eliminated using current interrupt technique during the potentiodynamic measurement. Therefore, the real polarization curve was obtained. The corrosion behavior was investigated by galvanostatic polarization, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results show a new form of passivation route. The steel dissolved actively below −0.388 VSCE, then became partly passivated from −0.388 to 1.448 VSCE, and fully passivated above 1.448 VSCE. The passive film was formed containing Fe2O3 and FeOOH, and resistant to SO42− ions. It not only blocked the direct dissolution of steel, but also facilitated oxygen evolution. The corrosion rates of steel samples decreased after the passivation.

Stress and Electrochemical Analyses of LiNixMnyCo1-x-YO2(NMC)/Graphite Lithium-Ion Battery with Real 3D Microstructures

LiNixMnyCo1-x-yO2 (NMC) is one of promising cathode materials in lithium-ion batteries (LIBs) for power tools and electric vehicles due to their higher specific capacity and energy density. However, it is observed that repeated cycling leads to micro-scale fracture along the grain boundaries in the secondary particles of NMC, and it could eventually cause low cycling stability and irreversible capacity retention. The aim of this study is to investigate the correlation of mechanical stresses and electrochemical battery degradation. Specifically, mechanical stress and strain caused by lithium intercalation and diffusion in both cathode and anode were calculated and crack initiation in particles was predicted. Furthermore, a modified Butler-Volmer equation, which accounts for the influence of mechanical stress on electrochemical reactions, is considered. In this study, we adopted real 3D microstructures of both anode (graphite) and cathode (NMC) based on over 100 images from a synchrotron radiation X-ray tomographic microscopy (SRXTM). The 3D finite element model (FEM) was developed by COMOSL Multiphysics 5.2a and followed by coupled electrochemical and mechanical analyses of a whole cell, including cathode, anode, and electrolyte. As the first step, the electrochemical model based on the microstructure was compared with results from the previous study with a simple geometry (e.g. spherical particles). Specifically, the real 3D microstructure model, concentration, polarization, over potential, and von-Mises stress distribution across both electrodes (e.g. graphite and NMC) were computed under different C-rates. We observed that effects of phase transformation of NMC on mechanical stress was significant during discharging processes. Moreover, the model revealed that at particle connections where exhibit complicated geometries and the bulged regimes of smaller curvature showed higher stress and were vulnerable to particle cracking. Finally, it is confirmed that mechanical stress plays important role in electrochemical performance. This computational model can make a solid foundation to understand the relationship between mechanical stress and electrochemical performance in NMC/graphite battery chemistry. It might be helpful to understand key factors in the deterioration of Lithium-ion batteries with higher C-rates and longer cycle life.

UV complete me: positivity bounds for particles with spin

For a low energy effective theory to admit a standard local, unitary, analytic and Lorentz-invariant UV completion, its scattering amplitudes must satisfy certain inequalities. While these bounds are known in the forward limit for real polarizations, any extension beyond this for particles with nonzero spin is subtle due to their non-trivial crossing relations. Using the transversity formalism (i.e. spin projections orthogonal to the scattering plane), in which the crossing relations become diagonal, these inequalities can be derived for 2-to-2 scattering between any pair of massive particles, for a complete set of polarizations at and away from the forward scattering limit. This provides a set of powerful criteria which can be used to restrict the parameter space of any effective field theory, often considerably more so than its forward limit subset alone.

Investigation of real polarization resistance for electrode performance in proton-conducting electrolysis cells

An equivalent circuit has firstly been proposed to evaluate proton-conducting electrolysis cells for their intrinsic electrode performance concealed by electronic conduction in electrolyte.

Planar density of vacuum charge induced by a supercritical Coulomb potential

Analytical expressions for the planar density of an induced vacuum charge are obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in an external electromagnetic field. Induced vacuum charge density is calculated and analyzed in subcritical and supercritical Coulomb potentials for massless and massive fermions. We argue that the virtual and so-called real vacuum polarizations contribute in an induced vacuum charge in a supercritical Coulomb potential. The behavior of the polarization vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. The real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in a supercritical Coulomb potential due to the real vacuum polarization is calculated. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supercritical Coulomb impurity.

The geometry of real reducible polarizations in quantum mechanics

The formulation of geometric quantization contains several axioms and assumptions. We show that for real polarizations we can generalize the standard geometric quantization procedure by introducing an arbitrary connection on the polarization bundle. The existence of reducible quantum structures leads to considering the class of Liouville symplectic manifolds. Our main application of this modified geometric quantization scheme is to quantum mechanics on Riemannian manifolds. With this method we obtain an energy operator without the scalar curvature term that appears in the standard formulation, thus agreeing with the usual expression found in the physics literature.

Influence of single-neutron stripping on near-barrier He6+Pb208 and He8+Pb208 elastic scattering

The influence of single-neutron stripping on the near-barrier elastic scattering angular distributions for the $^{6,8}\mathrm{He}+^{208}\mathrm{Pb}$ systems is investigated through coupled reaction channels (CRC) calculations fitting recently published data to explore the differences in the absorptive potential found in the scattering of these two neutron-rich nuclei. The inclusion of the coupling reduces the elastic cross section in the Coulomb-nuclear interference region for $^{8}\mathrm{He}$ scattering, whereas for $^{6}\mathrm{He}$ its major impact is on the large-angle elastic scattering. The real and imaginary dynamic polarization potentials are obtained by inverting the CRC elastic scattering $S$-matrix elements. These show that the main absorptive features occur between 11 and 12 fm for both projectiles, while the attractive features are separated by about 1 fm, with their main structures occurring at 10.5 fm for $^{6}\mathrm{He}$ and 11.5 fm for $^{8}\mathrm{He}$.

Initial Rotor Position Estimation Using Zero-Sequence Carrier Voltage for Permanent-Magnet Synchronous Machines

Both rotating and anticlockwise pulsating signal injection methods based on zero-sequence voltage sensing have been reported to have large signal-to-noise ratio and bandwidths, and great stability for the sensorless control of permanent-magnet synchronous machines. However, the initial rotor position estimation and magnetic polarity identification using zero-sequence voltage have not been investigated. Therefore, this paper presents two types of magnetic polarity identification methods, based on the amplitude variation of zero-sequence voltage due to saturation changing, and based on the secondary harmonics of zero-sequence voltage, for the two carrier injection methods, respectively. It is found that the amplitude variation based method using zero-sequence voltage has higher detection sensitivity for the real magnetic polarity compared to the conventional method using the carrier current. In contrast, the secondary harmonic based identification method using zero-sequence voltage for rotating signal injection has the advantage of fast response, and moreover has large signal amplitude and less distortion compared to the conventional secondary carrier current harmonics. However, the secondary harmonic method loses the capability for polarity detection for the anticlockwise pulsating injection method. Experiments are carried out on a laboratory permanent-magnet machine to verify the theoretical analyses.

Considerations of Oxide Species Coverage on the Kinetic Parameters of Pt-Based Catalysts

In order for hydrogen polymer electrolyte membrane fuel cell (PEMFC) technology to be economically competitive, overall system costs still need to be lowered. A key component of cost is the amount (grams) of Pt used in the membrane electrode assembly (MEA). Significant advances in electrocatalyst research, especially focused on the oxygen reduction reaction (ORR) for PEMFC cathodes, have thus been made and have led to the development of highly active catalysts capable of delivering target power at reduced Pt loadings.1 Unfortunately, as the Pt loading i.e. electrode roughness factor, decreases, an additional resistance emerges leading to voltage loss. This resistance, associated with phenomena at or near the Pt surface, is poorly understood and has been shown to have the greatest impact on low loaded Pt electrodes (<0.1 mgPt/cm2) operating at high current densities (>1.0 A/cm2). Therefore, an understanding of the kinetic parameters governing the electrochemical reactions, specifically at the cathode, is essential in order to distinguish between voltage losses that are kinetically derived from those originating from other sources. An understanding of the nature and mechanisms of performance losses in PEMFCs is essential in order for industry to best direct R&D resources. Discrepancies observed in theoretical kinetic predictions and real performance polarization curves for low Pt loaded MEAs (>0.1 mg Pt/cm2) have led to alterations in the simple Tafel kinetic model2 by including an additional term related to oxide coverage.3 While the operating cell potential inherently drops as the catalyst loading decreases, oxide-coverage kinetics become increasingly important in modeling performance especially when transitioning between catalyst surfaces with little to no oxide coverage to those with high oxide coverage. Since some kinetic parameter values change considerably when incorporating an oxide coverage term into the simple tafel model, it is important to know how dependent these changes are in regards to catalyst type and support, as well as in how oxide coverage is defined. Because specific oxide species generated at the catalyst surface can differ with changing conditions e.g. Pt-OH (1e- process), Pt-O (2e- process), it is difficult to obtain a unified model which accurately describes oxide formation. Subsurface oxide generation has also been shown to occur,4 which can skew interpretations of oxide measurements. Additionally, oxide formation has been shown to differ substantially among different catalyst surfaces and supports.This work attempts to clarify the impact that oxide species have on kinetic parameters (exchange current density (ios), reaction order (γ), activation energy (EA) etc.) for Pt-based catalysts. Experiments were performed under pure oxygen using a 5cm2 differential cell with MEAs consisting of Pt/V, Pt/HSC, and Pt alloy/HSC at loadings of 0.2 – 0.05 mg Pt/cm2. Sub-ambient system pressures were employed by means of a vacuum panel in order to lower pure oxygen partial pressure while minimizing gas transport effects. An example measurement is shown in Figure 1, with the oxide and transport free surface potential and current region highlighted. Interpretations of oxide measurement techniques as well as the impact of different catalyst surfaces and supports are discussed. As catalyst activity continues to improve, future implications and significance of oxide kinetics are also considered. Figure 1. iR-free potential vs log current density as a function of oxygen partial pressure for Pt/Vu electrocatalyst. The authors would like to acknowledge funding from the U.S. Department of Energy under CRADA #CRD-14-539.

Synthesis and electrochemical properties of dual doped spinels LiNixAlyMn2−x−yO4 via facile novel chelated sol–gel method as possible cathode material for lithium rechargeable batteries

LiMn2O4 and LiNixAlyMn2−x−yO4 (x=0.50; y=0.05–0.50) powders have been synthesized via facile sol–gel method using Behenic acid as active chelating agent. The synthesized samples are subjected to physical characterizations such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical studies viz., galvanostatic cycling properties, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). Finger print XRD patterns of LiMn2O4 and LiNixAlyMn2−x−yO4 fortify the high degree of crystallinity with better phase purity. FESEM images of the undoped pristine spinel illustrate uniform spherical grains surface morphology with an average particle size of 0.5µm while Ni doped particles depict the spherical grains growth (50nm) with ice-cube surface morphology. TEM images of the spinel LiMn2O4 shows the uniform spherical morphology with particle size of (100nm) while low level of Al–doping spinel (LiNi0.5Al0.05Mn1.45O4) displaying cloudy particles with agglomerated particles of (50nm). The LiMn2O4 samples calcined at 850 °C deliver the discharge capacity of 130 mAh/g in the first cycle corresponds to 94% columbic efficiency with capacity fade of 1.5 mAh/g/cycle over the investigated 10 cycles. Among all four dopant compositions investigated, LiNi0.5Al0.05Mn1.45O4 delivers the maximum discharge capacity of 126 mAh/g during the first cycle and shows the stable cycling performance with low capacity fade of 1 mAh/g/cycle (capacity retention of 92%) over the investigated 10 cycles. Electrochemical impedance studies of spinel LiMn2O4 and LiNi0.5Al0.05Mn1.45O4 depict the high and low real polarization of 1562 and 1100 Ω.

Real space CMB temperature and polarization formulas

I derive formulas for the real space CMB temperature and polarization by solving the first order Boltzmann equation for the Stokes parameters I, Q and U.

Recognizing magnetostratigraphy in overprinted and altered marine sediments: Challenges and solutions from IODP Site U1437

AbstractCore disturbance, drilling overprints, postdepositional acquisition of remanence, authigenic growth of magnetic iron sulfides, and alteration all contribute challenges to recognizing the primary magnetostratigraphy in marine sediments. We address these issues in a sequence of tuffaceous muds and volcaniclastics at International Ocean Discovery Program Site U1437 and produce the longest continuous magnetic polarity stratigraphy in the history of scientific ocean drilling. Remanence measurements were filtered to remove intervals affected by fluidization, plastic sediment disturbance, and core biscuiting. Drilling overprints are concentrated in the disturbed annulus surrounding intact core material. Bioturbation was limited to a vertical extent of at most 15 cm. Changes in sediment color, stiffness, and magnetic hysteresis all suggest that remanence was locked in within a few meters of the sediment–water interface. We did not observe any systematic offset between magnetostratigraphic and biostratigraphic datums. Authigenic growth of greigite, in response to both initial sulfate reduction in the upper 50 m of the sediment column and to deeper resupply of sulfate, has led to magnetic overprinting. Anomalous polarity artefacts, extending &lt;5 m and occurring within about 20 m below a real polarity transition, appear to be due to a chemical remanence acquired by greigite produced during early diagenesis. Diagenetic magnetic mineral alteration resulted in the progressive loss of fine‐grained magnetite, which enhanced susceptibility to drilling and postdrilling overprints and increased the resistance of these overprints to removal by conventional demagnetization. We recovered the magnetostratigraphic record from many samples with resistant overprints through low‐temperature demagnetization through the Verwey transition.

Large electrocaloric effect in BaTiO3 based multilayer ceramic capacitors

The electrocaloric effect (ECE) of multilayer ceramic capacitor (MLCC) of Y5V type was directly measured via a differential scanning calorimetry (DSC) method and a reference resistor was used to calibrate the heat flow due to the heat dissipation. The results are compared with those calculated from Maxwell relations by using the polarization data obtained from the polarization–electric field hysteresis loops. The direct method shows a larger ECE temperature change, which is accounted for the situation approaches an ideal condition. For the indirect method using Maxwell relations, only the polarization projection along the electric field was taken into account, which will be less than the randomly distributed real polarizations that contribute to the ECE. The MLCCs exhibit a broad peak of ECE around 80C, which will be favorite for the practical ECE cooling devices.

Extraction of polarization properties of the individual components of a layered system by using spectroscopic Mueller matrix analysis.

In semiconductor and optics fields, some devices are constructed with layered systems including two or three individual layers. Measurement of polarization properties of the individual components of these layered systems is often desired. In this paper, we present methods allowing the simultaneous extraction of the polarization parameters of the individual components by analyzing spectroscopic Mueller matrices (measured at two wavelengths). We have studied both retarder-retarder and retarder-polarizer-retarder systems. The validities of the methods were successfully tested using both simulations and real polarization systems.

Buckling Effect Induced Abnormal Out of Plane Domain Stripe in BiFeO3 Single-Crystalline Thin Film Investigated by Piezoresponse Force Microscopy

We demonstrated a BiFeO3 single-crystalline thin film, which was deposited on a (100) SrTiO3 single-crystal substrate by using a pulse laser deposition technology. The as-grown domain structure was investigated by piezoresponse force microscopy, which possesses two preferential downward <111> orientations in an angle of 71°. We have found that the abnormal out of plane stripe domain patterns match with the in-plane domains. According to schematic diagrams and quantitative equations, we explained that the coupling between the out of plane and in-plane domains arise from the buckling effect, which can open a new way to reconstruct the real polarization vectors.

Correct evaluation of the effective concentration polarization influence in membrane-assisted devices. Case study: H2 production by Water Gas Shift in Pd-membrane reactors

In this paper, a non-conventional approach is introduced to correctly measure the overall effective influence of concentration polarization in membrane-assisted devices. The basis of this study starts from considering that the Concentration Polarization Coefficient (CPC) tends to become high in those device zones where permeation driving force is relatively small (i.e., small flux). Therefore, these zones have to provide a small contribution to the overall polarization level, as membrane is not influential to the process. However, if calculating the average CPC along the device using the standard method, an unrealistic over-estimation of the overall polarization level results, which is not representative of the real behavior of device. To avoid such an issue, a novel coefficient, here-named Effective Average CPC (EAC), is introduced and used. This coefficient, representing a more useful method to determine the real polarization extent in a membrane-assisted device, is then investigated as a function of key-engineering working parameters, like temperature, total feed and permeate pressure and Gas Hourly Space Velocity (GHSV), determining the conditions allowing the overall polarization level to be minimized.

Polarimeters for the SPASCHARM Experiment

A beam channel of polarized protons and antiprotons produced from decays of [Formula: see text]- and anti-[Formula: see text]-hyperons for the SPASCHARM experiment is to be built at IHEP U-70 accelerator in Protvino, Russia. The methods for tagging and measuring polarization of the beam (anti)protons are discussed in this report. The fast on-line beam tagging exploits the correlations between polarization and kinematics of (anti)protons originated from (anti)[Formula: see text]-decays. In the intermediate focus of primary target, decay (anti)protons of different transverse polarizations are spatially dispersed transversely with respect to the beam axis. The tagging system, consisting of fast beam detectors with good spatial resolution, measures the momentum and trajectory of each beam particle, including its position at the intermediate focus, thus allowing instant (on-line) assignment of the transverse polarization value to each (anti)proton. This system is also extremely useful for the beam channel tuning. While being fast and convenient, the polarization tagging fully relies on computing of particle transportation in the beam channel. In order to verify the real beam polarization and operating of the tagging system and beam channel, the independent absolute beam polarimetry is to be used. It is based on measuring the spin asymmetries in elastic scattering of beam (anti)protons in Coulomb-Nuclear Interference (CNI) and diffractive kinematic regions. It is estimated that less than one week of data taking would allow measuring an absolute beam polarization at the statistical accuracy of [Formula: see text]4–5%.

Wigner function of a qubit

We show that real polarization method can be effectively used to geometrically quantize physical systems with compact phase space, like the spin. Our method enables us to construct a wave function of a qubit in both position and momentum representations and also its Wigner function. These results can be used in quantum informatics.