Moment Components Research Articles

Discovering the Elusive Global Minimum in a Ternary Chiral Cluster: Rotational Spectra of Propylene Oxide Trimer.

The chirality controlled conformational landscape of the trimer of propylene oxide (PO), a prototypical chiral molecule, was investigated using rotational spectroscopy and a range of theoretical tools for conformational searches and for evaluating vibrational contributions to effective structures. Two sets of homochiral (PO)3 rotational transitions were assigned and the associated conformers identified with theoretical support. One set of heterochiral (PO)3 transitions was assigned, but no structures generated by one of the latest, advanced conformational search codes could account for them. With the aid of a Python program, the carbon atom backbone and then the heterochiral (PO)3 structure were generated using 13C isotopic data. Excellent agreement between theoretical and experimental rotational constants and relative dipole moment components of all three conformers was achieved, especially after applying vibrational corrections to the rotational constants.

High‐order moment multi‐sensor fusion filter design of Markov jump linear systems

To solve the problem of high-order moment Gaussian distribution (HGD) noise in state estimation, a fusion filter for Markov jump linear systems (MJLSs) with high-order moment information obtained from sensor data is designed. To obtain high-order moment information, the multi-sensor MJLS is converted to a single-mode system composed of high-order moment components by using a cumulant generating function. Next, a filter design based on Bayesian theory is established to achieve state estimation with a high-order moment information form according to the transformed single-mode deterministic system. Subsequently, a high-order moment fusion technique based on entropy theory is proposed to obtain a more accurate estimation result of the state by using the high-order moment information obtained from various sensors. Comparing the first- and second-order moment information obtained by traditional Gaussian distribution, the HGD introduces higher-order moment information and makes the fusion process more reasonable. In this way, a more precise and reasonable performance of the state estimation is achieved, depending on the sensor fusion technique. To confirm the effectiveness and advantages of the proposed method, a numerical simulation example is provided with various fusion methods. Thus, the performance of the proposed fusion filter design is verified.

Level anti-crossings of a nitrogen-vacancy center in diamond: decoherence-free subspaces and 3D sensors of microwave magnetic fields

Nitrogen-vacancy (NV) centers in diamond have become an important tool for quantum technologies. All of these applications rely on long coherence times of electron and nuclear spins associated with these centers. Here, we study the energy level anti-crossings of an NV center in diamond coupled to a first-shell 13C nuclear spin in a small static magnetic field. These level anti-crossings (LACs) occur for specific orientations of the static magnetic field due to the strong non-secular components of the Hamiltonian. At these orientations we observe decoherence-free subspaces, where the electron spin coherence times () are 5–7 times longer than those at other orientations. Another interesting property at these LACs is that individual transition amplitudes are dominated by a single component of the magnetic dipole moment. Accordingly, this can be used for vector detection of microwave magnetic fields with a single NV center. This is particularly important to precisely control the center using numerical optimal control techniques.

Torsional States and Tunneling Probability in HOSOH, DOSOD, and DOSOH Molecules Analyzed at the CBS Limit.

Torsional vibrations of a sulfoxylic acid molecule (HOSOH) and its two deuterated isotopologues were analyzed for the first time. Harmonic and anharmonic calculations of the vibrational frequencies of the trans- and cis-conformers were performed. More rigorous consideration of the torsional vibrations was made based on 2D potential energy and kinematic coefficient surface calculations. These calculations were made at the MP2/cc-pVTZ and MP2/cc-pVQZ levels of theory, and then the results were extrapolated to the complete basis set limit. The 2D surface of the zero-point vibrational energy of a sulfoxylic acid molecule was calculated at the MP2/cc-pVTZ level of theory in anharmonic approximation and taken into account. The energies of the torsional states were found by numerical solution of the vibrational Schrödinger equation of the restricted dimensionality using the Fourier method. 2D surfaces of the dipole moment components were calculated too. Using all these data, the torsional IR spectra of the trans- and cis-conformers of the HOSOH, DOSOD, and DOSOH molecules were also modeled at different temperatures.

Interfacial-hybridization-modified Ir ferromagnetism and electronic structure in LaMnO3/SrIrO3 superlattices

Artificially fabricated 3$d$/5$d$ superlattices (SLs) involve both strong electron correlation and spin-orbit coupling in one material by means of interfacial 3$d$-5$d$ coupling, whose mechanism remains mostly unexplored. In this work we investigated the mechanism of interfacial coupling in LaMnO$_3$/SrIrO$_3$ SLs by several spectroscopic approaches. Hard x-ray absorption, magnetic circular dichroism and photoemission spectra evidence the systematic change of the Ir ferromagnetism and the electronic structure with the change of the SL repetition period. First-principles calculations further reveal the mechanism of the SL-period dependence of the interfacial electronic structure and the local properties of the Ir moments, confirming that the formation of Ir-Mn molecular orbital is responsible for the interfacial coupling effects. The SL-period dependence of the ratio between spin and orbital components of the Ir magnetic moments can be attributed to the realignment of electron spin during the formation of the interfacial molecular orbital. Our results clarify the nature of interfacial coupling in this prototypical 3$d$/5$d$ SL system and the conclusion will shed light on the study of other strongly correlated and spin-orbit coupled oxide hetero-interfaces.

Spin–orbit torque-induced multiple magnetization switching behaviors in synthetic antiferromagnets

This paper studies spin–orbit torque (SOT) switching behaviors in synthetic antiferromagnet (SyAF) structures of Ta/[Pt/Co]m/Ru/[Co/Pt]n, which are asymmetric between the upper multilayer (UML) and the bottom multilayer (BML). The SOT-induced magnetization switching loops show multiple transitions of switching orientations between clockwise and anticlockwise with an increasing in-plane magnetic field, determined by the effects of the Dzyaloshinskii–Moriya interaction from both the BML and UML in the different stacking structures. Moreover, the field-free SOT switching was observed in the structure of Ta/[Pt/Co]3/Ru (0.5)/[Co/Pt]4. It can be attributed to the horizontal component of magnetic moments in its UML acting as an equivalent field. Therefore, the SyAF structures could be potential candidates for the future SOT-based spintronic devices.

Application of artificial intelligence models for predicting time-dependent spring-back effect: The L-shape case study

The role of forces and moments in the spring-back effect in L-shaped carbon-epoxy composites is investigated. Statistical models and artificial intelligence were used to prove the significance of these physical quantities in the angu-lar deformation of these composites. We follow the spring-in deformation as a function of time three years span, and recently we reclassify the recovery on angular deformation due to residual cure as spring-back. This angular deforma-tion measured for different configurations tends to stabilize after approximately three years after the composite fabrication. The variation on the angular de-formation displays direct dependence with the residual curing process for the matrix resin of each specimen. Thirteen angular deformation were measured 3 years span. We calculated the components of forces (N) and moments (M) indirectly through the classical laminate theory (CLT) for each composite con-figuration. The Generalized Additive Models (GAM) evaluate the significance of the forces and moments on spring-back effect. Their output results identify the linear and nonlinear cofactors role as spring-back influencers. The Random Forest (RF) model ranked the influence of forces and moments in spring-back deformation. Both statistical models are complementary, GAM predicts the impact of cofactors with accuracy close to 90%, whereas Randon Forest model explains the angular deformation in the mean values with accuracy greater than 91%.

Teaching the electrical origins of the electrocardiogram: An introductory physics laboratory for life science students

We present the design, pedagogical logic, and assessment of a laboratory and supporting materials that integrate a clinical academic cardiologist's understanding of the origins of the electrocardiogram (ECG) with a physics educator's insights into how to teach the underlying physics at the introductory level to life science students. In this article, we explain the choices made throughout the design process, connect a more advanced treatment of the physics to our approach, and present our assessment of the curriculum. Before the laboratory, students learn the cellular origins of the electric dipole potential produced by the heart on the body's surface, including a simple physical model for the electrical activity of excitable cells, and learn to interpret the measured voltages of an ECG as probing components of the heart's time-varying electric dipole moment. In the laboratory, students measure their own ECGs and analyze the data accordingly; they animate their data to display their own heart's dipole moment for a single heartbeat. Our results from the assessment of student understanding and attitudes indicate that although students find the content challenging, nearly all students find it at least moderately interesting, and for about a quarter of the students in the course, this lab plays a highly meaningful part in connecting physics to medicine.

The extrema point deviatoric moment component

The concern plate’s behavior was the growth of the extrema positive tensors of both mean (hydrostatic) and deviatoric moments. Systematic consideration of the limits and growth responses of the mean and deviatoric tensors at the extrema positive sections were calculated. It was found that the use of the shorter dimension for the moment normalization in both directions preserves the directional influence of the dimensions and isolates clearly the hydrostatic phenomenon. Moreover, the presence of non-identical boundary conditions in the plate on two perpendicular directions was found to result in the deviation of the two-way action of behavior. Consequently, a novel understanding of the two-way plate action has been achieved. In such understanding, the pure two-way action accompanies the occurrence of a hydrostatic curvature (or moment) at a plate’s extrema positive point. At the later state, the hydrostatic and deviatoric tensor components would be equal. Based on linear and multi-Stage regression analysis, the growth of the normalized hydrostatic moment component (CHMc) with the geometrical aspect has been deemed to follow a linear regression model, as well as the growth of the deviatoric moment component with the geometrical aspect ratio, has been deemed to follow the sigmoidal, Morgan-Mercer-Flodin (MMF) nonlinear regression model.

Calculation and reduction of sound radiation from a thin plate structure excited by complex inputs

This paper presents a new method to compute the sound radiation emanating from a thin plate structure due to complex inputs that include normal force and in-plane bending moments. A set of new formulas for the sound radiation of baffled and unbaffled plates are derived by substituting the moment components of the plates with the equivalent couples using finite difference analysis. This approach allows to calculate sound power purely by the input location and amplitude of each component. Thus, it enables faster, more accurate calculations than the existing methods such as the average radiation efficiency analysis and the radiation mode analysis. Based on these calculations, the vibroacoustic characteristics of a simply supported rectangular plate are analyzed. The computational results are in good agreement with the finite element analysis results. It is suggested to keep the grid spacing less than 2.5% of the shortest dimension of the target structure to accurately calculate the moment mobility. Accurate sound power can also be obtained by downsampling the grid to satisfy ka<0.2 within the frequency band of interest. Furthermore, a sound reduction method is proposed by analyzing each structural mode's contribution to the sound radiation. Using the proposed methodology, sound power at a specific frequency or multi-frequency range can be reduced or amplified by changing the location and angle of the complex inputs.

Higher co-moments and adjusted Sharpe ratios for cryptocurrencies

We report the results of regressing the Sharpe ratios of 72 cryptocurrencies on first, second and third co-moments of their returns. Our general aim is to examine the risk-return trade-off characteristics of cryptocurrencies. In other words, to determine whether the returns of cryptocurrencies justify their huge volatility especially with regard to the higher moment components of their systemic risk? We find that adjusted Sharpe ratios of the cryptocurrencies and traditional indexes do not differ significantly in this respect.

Pressure tuning of the anomalous Hall effect in the chiral antiferromagnet Mn3Ge

We report on the pressure evolution of the giant anomalous Hall effect (AHE) in the chiral antiferromagnet Mn$_3$Ge. The AHE originating from the non-vanishing Berry curvature in Mn$_3$Ge can be continuously tuned by application of hydrostatic pressure. At room temperature, the Hall signal changes sign as a function of pressure and vanishes completely at $p=1.53$ GPa. Even though the Hall conductivity changes sign upon increasing pressure, the room-temperature saturation value of 23 ${\rm \Omega^{-1}cm^{-1}}$ at 2.85 GPa is remarkably high and comparable to the saturation value at ambient pressure of about 40 ${\rm \Omega^{-1}cm^{-1}}$. The change in the Hall conductivity can be directly linked to a gradual change of the size of the in-plane components of the Mn moments in the non-collinear triangular magnetic structure. Our findings, therefore, provide a route for tuning of the AHE in the chiral antiferromagnetic Mn$_3$Ge.

Overtone spectroscopy of v(C=O) stretching vibration of hexafluoroacetone: Experimental and ab initio determination of peak positions, absolute intensities, and band shapes

Infrared overtone spectra of the ν(C = O) stretching vibration (ν1) of gaseous hexafluoroacetone ((CF3)2C = O, HFA) were recorded in the spectral range of 7450-3300 cm-1 with a resolution of 0.1 cm-1. Experimental absolute IR intensities and vibrational band centers of the overtones 2ν1, 3ν1, 4ν1 of HFA were measured and compared with their ab initio counterparts, calculated by the second-order canonical vibrational perturbation theory (CVPT2). A hybrid potential energy surface (PES) was evaluated using the quantum-mechanical models MP2/cc-pVQZ for harmonic and MP2/cc-pVTZ for anharmonic parts. Cubic surfaces of dipole moment components were determined using the MP2/cc-pVTZ model. The predicted IR intensities for the first and second overtones reproduced the experimental values with a discrepancy of 6% and 9%, respectively. A weak Fermi resonance between the first overtone 2ν1 and combination tone ν1 + ν2 + ν8 was predicted. The appropriate model was employed for simulating the bands studied using: (i) the asymmetric-top vibration-rotational structure of the ν1 mode, (ii) the inhomogeneous band structure due to contributions of the vibrational states populated at the room temperature, and (iii) the homogeneous broadening of each vibration-rotation transition due to the intramolecular vibrational redistribution (IVR). The rotational and vibrational anharmonic constants were taken from the ab initio calculations, whereas the IVR data were obtained from the experimental data of Chekalin et al. (JPCA 2014, 118:955) with a time resolution of ≈100 fs. A good level of agreement of the predicted shapes of bands studied with experiment is achieved.

Thrusters Physical Model Formalization With Regard to Situational and Identification Factors of Motion Modes

Within the framework of the research of diagnos-tics and prediction of technical state of ship power plants (SPP) of combined propulsion complexes (CPC) depend-ences of correcting factors influencing components of thrusts and moments, proportional dimensions of model and real thrusts (THRs), tied to the original geometry were obtained. This was done by formalizing the physical model of the azimuth thruster with the means of identifying the degradation effects on the flow lines of the propellers by methods of computational hydrodynamics. The technique of improving the structure of the mathematical models of the SPP CPC according to experimental studies by measur-ing the input and output parametric coordinates of the THRs CPC of a vessel operating in the dynamic positioning mode is announced.

“I Already Know That Smoking Ain’t Good for Me”: Patient and Clinician Perspectives on Lung Cancer Screening Decision-Making Discussions as a Teachable Moment

Lung cancer screening (LCS) is now recommended for people at high risk of dying of lung cancer. The purpose of this study was to use the LCS decision discussion as a case study to understand possible underlying components of a teachable moment to enhance motivation for smoking cessation. The study investigated how patients and clinicians communicate about smoking. In-depth, semi-structured interviews were performed of the experiences of 51 individuals who formerly or currently smoked who were offered LCS and 24 clinicians. Only the baseline interviews were used because including the follow-up interviews would have been beyond the scope of this article. The interviews focused on communication about smoking, the perceived importance of discussing smoking and screening together, and patients' perceived challenges to smoking cessation. Patients and clinicians differed in their views on the role of the LCS decision discussion as a teachable moment. Although clinicians felt that this discussion was a good opportunity to positively influence smoking behaviors, neither patients nor clinicians perceived the discussion as a teachable moment affecting smoking behaviors. Other motivating factors for smoking cessation were found. Our findings indicate that LCS decision discussions are not currently a teachable moment for behavior change in smoking cessation, but perhaps clinicians could address other aspects of communication to enhance motivation for cessation. Our hypothesized teachable moment model helps explain that there may not be sufficient emotional response elicited during the discussion to motivate a major behavior change such as smoking cessation.

Isotropic seismic radiation from rock damage and dilatancy

SUMMARYWe present semi-analytical and numerical results on isotropic radiation expected to be generated by seismic sources with damaged dilatant materials that sustain during failure an overall shear deformation. The results are derived for inclusions with different stiffness components, including those responsible for shear-volumetric coupling in dilatant material, and different geometries, in a surrounding elastic solid. The obtained relations indicate that the isotropic seismic potency and seismic moment components are proportional to the shear potency components multiplied by the aspect ratio between the thickness and length of the source zone. For a typical rupture zone with a thin tabular geometry, the expected small aspect ratio explains the general seismological observations of small isotropic radiation. However, isotropic radiation induced by dynamic dilation for short and thick sources is more pronounced and may reach for spherical sources sustaining shear deformation 18 per cent of the shear components. Sources that include also tensile components and explosions can produce larger isotropic radiation. The results provide rigorous relations that can be used to estimate different source properties in numerical simulations, experiments and field studies.

Time-Varying Consumer Disagreement and Future Inflation

The inflation expectations of over 285 thousand consumers are used to develop ‘model-free’ estimates of the monthly cross-sectional mean, dispersion, asymmetry and extremeness of inflation expectations from 1995 to 2016. The moments provide a novel and direct measure of time-varying consumer disagreement about prices. I find that the higher-order cross-sectional moments of inflation expectations are highly informative about future inflation. In contrast to popular assumptions, these moments do not appear to be noise. Even after accounting for historical economic data, the ‘unanticipated’ components of the higher-order moments are significantly associated with future inflation. In effect, the higher order moments are neither noise nor conventional economic news. The results have significant implications for the widespread practice of trimming inflation expectations data. The results also have implications for the study of information rigidities, indicating that consumer inflation expectations broadly reflect two types of consumers. The first type update their information set at a much faster rate than is typically estimated or assumed. The second type have very high information rigidities and only update their information set in response to major economic events.

First measurement of the total gravitational quadrupole moment of a black widow companion

ABSTRACT We present the first measurement of the gravitational quadrupole moment of the companion star of a spider pulsar, namely the black widow PSR J2051–0827. To this end, we have re-analysed radio timing data using a new model that is able to account for periastron precession caused by tidal and centrifugal deformations of the star as well as by general relativity. The model allows for a time-varying component of the quadrupole moment, thus self-consistently accounting for the ill-understood orbital period variations observed in these systems. Our analysis results in the first detection of orbital precession in a spider system at $\dot{\omega } = -68{_{.}^{\circ}}6_{-0{_{.}^{\circ}}5}^{+0{_{.}^{\circ}}9}$ yr−1 and the most accurate determination of orbital eccentricity for PSR J2051–0827 with e = (4.2 ± 0.1) × 10−5. We show that the variable quadrupole component is about 100 times smaller than the average quadrupole moment $\bar{Q} = -2.2_{-1}^{+0.6} \times 10^{41} \ {\rm kg\,m^2}$. We discuss how accurate modelling of high-precision optical light curves of the companion star will allow its apsidal motion constant to be derived from our results.

Active Actuating of a Simply Supported Beam with the Flexoelectric Effect.

Piezoelectric materials with the electro-mechanical coupling effect have been widely utilized in sensors, dampers, actuators, and so on. Engineering structures with piezoelectric actuators and sensors have provided great improvement in terms of vibration and noise reduction. The flexoelectric effect—which describes the coupling effect between the polarization gradient and strain, and between the strain gradient and electric polarization in solids—has a fourth-rank order tensor electro-mechanical coupling coefficient, and in principle makes the flexoelectricity existing in all insulating materials and promises an even wider application potential in vibration and noise control. In the presented work, a flexoelectric actuator was designed to actuate a simply supported beam. The electric field gradient was generated by an atomic force microscopy probe. Flexoelectric control force and moment components could be induced within the flexoelectric control layer. As flexoelectricity is size-dependent, the key parameters that could affect the actuating effect were examined in case studies. Analytical results showed that the induced flexoelectric control moment was strongly concentrated at the probe location. The controllable transverse displacement of the simply supported beam was calculated with the modal expansion method. It was found that the controllable transverse displacement was dependent on the probe location as well.

Actuator 기법을 이용한 프로펠러 3축 성분 힘/모멘트 해석

For aerodynamic performance and stability analysis of distributed propulsion aircraft which adopt many propellers/rotors, all the 3-axial components forces and moments must be properly taken into account. In this study, two actuator methods have been established to be capable of numerical simulations including all the force and moment components produced by rotor/propeller. A procedure in which the 3-axial components are transformed from the aerodynamic force and moment of blade elements has been added to actuator disk method(ADM) and actuator surface method(ASM). The numerical analyses are carried out for a single propeller of quad tilt propeller(QTP) at various flight conditions including the variation of side slip angle. The results are compared with wind tunnel test data and full CFD simulation with overset grid. All the force and moment components are found to agree very well in terms of engineering purposes and the present methods are identified to be numerically very efficient compared to full CFD. Power-on effect and longitudinal stability of the full configuration of QTP is further analyzed by carrying out the additional numerical simulations. The results indicate that the present methods is practically very useful to investigate the aerodynamic performance of distributed propulsion aircraft.