Moment Components Research Articles

Spin decoupling under a staggered field in the Gd2Ir2O7 pyrochlore

The influence of a staggered molecular field in frustrated rare-earth pyrochlores, produced via the magnetic iridium occupying the transition metal site, can generate exotic ground states, such as the fragmentation of the magnetization in the Ho compound. At variance with the Ising Ho$^{3+}$ moment, we focus on the behavior of the quasi isotropic magnetic moment of the Gd$^{3+}$ ion at the rare-earth site. By means of macroscopic measurements and neutron scattering, we find a complex situation where different components of the magnetic moment contribute to two antiferromagnetic non-collinear arrangements: a high temperature all in - all out order induced by the Ir molecular field, and Palmer and Chalker correlations that tend to order at much lower temperatures. This is enabled by the anisotropic nature of the Gd-Gd interactions and requires a weak easy-plane anisotropy of the Gd$^{3+}$ moment due to the mixing of the ground state with multiplets of higher spectral terms.

Direct and indirect effects of joint torque inputs during an induced speed analysis of a swinging motion

This study proposed a method to quantify direct and indirect effects of the joint torque inputs in the speed-generating mechanism of a swinging motion. Linear and angular accelerations of all segments within a multi-linked system can be expressed as the sum of contributions from a joint torque term, gravitational force term and motion-dependent term (MDT), where the MDT is a nonlinear term consisting of centrifugal force, Coriolis force and gyroscopic effect moment components. Direct effects result from angular accelerations induced by a joint torque at a given instant, whereas indirect effects arise through the MDT induced by joint torques exerted in the past. These two effects were quantified for the kicking-side leg during a rugby place kick. The MDT was the largest contributor to the foot centre of gravity (CG)’s speed at ball contact. Of the factors responsible for generating the MDT, the direct and indirect effects of the hip flexion-extension torque during both the flight phase (from the final kicking foot take-off to support foot contact) and the subsequent support phase (from support foot contact to ball contact) were important contributors to the foot CG’s speed at ball contact. The indirect effect of the ankle plantar-dorsal flexion torque and the direct effect of the knee flexion-extension torque during the support phase showed the largest positive and negative contributions to the foot CG’s speed at ball contact, respectively. The proposed method allows the identification of which individual joint torque axes are crucial and the timings of joint torque exertion that are used to generate a high speed of the distal point of a multi-linked system.

АНАЛИЗ ВЛИЯНИЯ КОНСЕРВАТИВНОГО СГЛАЖИВАНИЯ НА ТОЧНОСТЬ ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ ДИНАМИЧЕСКОГО УПРУГОПЛАСТИЧЕСКОГО ВЫПУЧИВАНИЯ СФЕРИЧЕСКИХ ОБОЛОЧЕК

Large changes of a lead spherical shell enclosed in an aluminum spacesuit under the action of an overload pulse are considered. The defining system of equations is formulated in Lagrange variables in a two-dimensional (axisymmetric) formulation. Strain and stress rates are determined in the local coordinate system. Kinematic relations are recorded in the metric of the current state. The relations of the flow theory with isotropic hardening are used as state equations. The contact interaction of the shell and the spacesuit is modeled by non-penetration conditions taking into account friction. The numerical solution of the problem under given boundary and initial conditions is based on the finite element method moment scheme and the explicit time integration “cross” type scheme. 4-node isoparametric finite elements with bilinear form functions are used to discretize the defining system of equations for spatial variables. To suppress the numerical solution high-frequency oscillations, the procedure of nodal displacements rates conservative smoothing is used. As shown by the results of numerical research spherical shell in the process of intensive dynamic loading undergoes large deformation and rotation angles as a rigid whole. The calculation results reliability is confirmed by a good correspondence to the experimental data. The influence of conservative smoothing procedure and moment components of deformations and stresses on the solution accuracy is analyzed. It is shown that without conservative smoothing procedure using, the shape of the spherical shell buckling obtained in the calculation does not correspond to the experimental data. Neglect of the moment components of strains and stresses leads to the development of instability of the “hourglass” type.

Normality tests for latent variables

We exploit the rationale behind the Expectation Maximization algorithm to derive simple to implement and interpret LM normality tests for the innovations of the latent variables in linear state space models against generalized hyperbolic alternatives, including symmetric and asymmetric Student ts. We decompose our tests into third and fourth moment components, and obtain one‐sided likelihood ratio analogues, whose asymptotic distribution we provide. When we apply our tests to a common trend model which combines the expenditure and income versions of US aggregate real output to improve its measurement, we reject normality if the sample period extends beyond the Great Moderation.

АНАЛИЗ ВЛИЯНИЯ КОНСЕРВАТИВНОГО СГЛАЖИВАНИЯ НА ТОЧНОСТЬ ЧИСЛЕННОГО МОДЕЛИРОВАНИЯ ДИНАМИЧЕСКОГО УПРУГОПЛАСТИЧЕСКОГО ВЫПУЧИВАНИЯ СФЕРИЧЕСКИХ ОБОЛОЧЕК

Large changes of a lead spherical shell enclosed in an aluminum spacesuit under the action of an overload pulse are considered. The defining system of equations is formulated in Lagrange variables in a two-dimensional (axisymmetric) formulation. Strain and stress rates are determined in the local coordinate system. Kinematic relations are recorded in the metric of the current state. The relations of the flow theory with isotropic hardening are used as state equations. The contact interaction of the shell and the spacesuit is modeled by non-penetration conditions taking into account friction. The numerical solution of the problem under given boundary and initial conditions is based on the finite element method moment scheme and the explicit time integration “cross” type scheme. 4-node isoparametric finite elements with bilinear form functions are used to discretize the defining system of equations for spatial variables. To suppress the numerical solution high-frequency oscillations, the procedure of nodal displacements rates conservative smoothing is used. As shown by the results of numerical research spherical shell in the process of intensive dynamic loading undergoes large deformation and rotation angles as a rigid whole. The calculation results reliability is confirmed by a good correspondence to the experimental data. The influence of conservative smoothing procedure and moment components of deformations and stresses on the solution accuracy is analyzed. It is shown that without conservative smoothing procedure using, the shape of the spherical shell buckling obtained in the calculation does not correspond to the experimental data. Neglect of the moment components of strains and stresses leads to the development of instability of the “hourglass” type.

Seismic sources at discontinuities: unambiguous moment and potency components

Seismic sources at discontinuities: unambiguous moment and potency components

Influence of synthesized thiourea derivatives as a prolific additive with tris(1,10-phenanthroline)cobalt(II/III)bis/tris(hexafluorophosphate)/ hydroxypropyl cellulose gel polymer electrolytes on dye-sensitized solar cells

An exceptional approach of appending tris(1,10-phenanthroline)cobalt(II)/(III)bis/tris(hexafluorophosphate) and synthesized tetramethyl benzidine-based thiourea derivatives as novel additives with hydroxypropyl cellulose are used to construct a gel polymer electrolyte for DSSC. The thiourea derivatives are synthesized using the cost-effective method. The synthesized derivatives are confirmed by 1H, 13C NMR and mass spectroscopy. The conductivity, surface and redox potential of thiourea derivatives doped Co2+/Co3+ redox electrolytes are scrutinized by impedance spectra, FTIR, UV, XRD. A density functional theory method with full geometry optimization is used to elucidate the adsorption of the symmetrical thiocarbamides on TiO2 (101) surface progressing with electron donating/accepting groups. All the organic compounds display a negative shift on the TiO2 Fermi level simultaneously by adsorption and rebutted as an escalated additive in stable Co(II/III)phen redox electrolyte of the dye-sensitized TiO2 solar cell. This impulse effect influences the sorbate dipole moment component normal to TiO2 surface plane; further, the stable redox mediator and hydroxypropyl cellulose deliver a good performance in a dye-sensitized solar cell. The newly synthesized thiourea derivatives doped Co2+/Co3+ with hydroxypropyl cellulose reports high solar to electric conversion, particularly 1,1'-(3,3′,5,5′-tetramethyl-[1,1′-biphenyl]-4,4′-diyl)bis(3-(3,4,5-trimethoxy phenyl)thiourea) (additive-6) doped redox electrolyte shows an outstanding efficiency (ŋ) of 9.1% under the sunlight irradiation of about 70 mW/cm2.

Spin Moment of a Surface Wave at the Interface between Hyperbolic and Topological Insulators

Commonly, a surface wave traveling along the interface between isotropic media has a spin moment that lies in the plane of the interface and is perpendicular to the direction of propagation. Here, we show that, if one of the two media is a topological insulator, the spin moment vector has a component that is normal to the surface of the interface and is proportional to odd integers. The appearance of the normal component of the spin moment is associated with the topological magnetoelectric effect, as a result of which the polarization of the wave changes upon passage through the interface.

Reconstruction of Equivalent Emission Sources for PCBs From Near-Field Scanning Using a Differential Evolution Algorithm

An efficient method to extract equivalent radiated emission sources for printed circuit boards (PCBs) from near-field (NF) scanning data is presented. The equivalent sources are represented by elemental magnetic dipoles placed over a planar surface on the component side of a PCB. A global optimization procedure, based on the differential evolution algorithm, is used to determine the components of each dipole moment, by exploiting only the magnitude of the scanned NF data. The number and positions of the equivalent dipoles are predetermined by analyzing the scanning NF data, which is based on the NF radiation pattern of a single straight trace on a PCB. The effects of both of the spacing of the scanning points and the distance between the scanning and the reconstruction planes on the accuracy of the reconstructed results are studied. The proposed method is validated by the comparison of the reconstructed and full-wave results for PCBs with different types of traces.

Is a Normal Copula the Right Copula?

ABSTRACTWe derive computationally simple and intuitive expressions for score tests of Gaussian copulas against generalized hyperbolic alternatives, including symmetric and asymmetric Student t, and many other examples. We decompose our tests into third and fourth moment components, and obtain one-sided Likelihood Ratio analogs, whose standard asymptotic distribution we provide. Our Monte Carlo exercises confirm the reliable size of parametric bootstrap versions of our tests, and their substantial power gains over alternative procedures. In an empirical application to CRSP stocks, we find that short-term reversals and momentum effects are better captured by non-Gaussian copulas, whose parameters we estimate by indirect inference. Supplementary materials for this article are available online.

Nonstationary Axisymmetric Motion of an Elastic Momentum Half-Space Under Nonstationary Normal Surface Displacements

An elastic homogeneous isotropic half-space filled with the Cosserat medium has been considered. The deformed state is characterized by independent displacement and rotation vectors. At the initial time and at infinity, there are no perturbations.On the boundary of a half-space, normal displacements are given. All components of the stress–strain state are supposed to be limited. A cylindrical coordinate system with an axis directed inward to the half-space has been used. With axial symmetry, the resolving system of equations includes three hyperbolic equations with respect to the scalar potential and the nonzero components of the vector potential and the rotation vector. The components of displacement vectors, rotation angle, stress tensors, and stress moments are related to potentials by known relationships. The solution of the problem has been sought in the form of generalized convolutions of a given displacement with corresponding superficial influence functions. These functions have been constructed using a Hankel transform with respect to the radius and a Laplace transform with respect to time. All images have three terms. The first of these terms corresponds to the tension–compression wave, and the remaining two are determined by the associated shear and rotation waves. The originals of the first components have been found accurately through successive inversion of transforms. For the remaining terms, we have used expansion in power series in a small parameter characterizing the relation between shear and rotation waves. The images of the first two coefficients of these series have been found. The corresponding originals have been determined by successive inversion of transforms. Examples of calculations of the regular components of the influence function of a granular composite of aluminum shot in an epoxy matrix have been given.

Anisotropy in the magnetic interaction and lattice-orbital coupling of single crystal Ni3TeO6

This investigation reports on anisotropy in the magnetic interaction, lattice-orbital coupling and degree of phonon softening in single crystal Ni3TeO6 (NTO) using temperature- and polarization-dependent X-ray absorption spectroscopic techniques. The magnetic field-cooled and zero-field-cooled measurements and temperature-dependent Ni L3,2-edge X-ray magnetic circular dichroism spectra of NTO reveal a weak Ni-Ni ferromagnetic interaction close to ~60 K (TSO: temperature of the onset of spin ordering) with a net alignment of Ni spins (the uncompensated components of the Ni moments) along the crystallographic c-axis, which is absent from the ab-plane. Below the Néel temperature, TN~ 52 K, NTO is stable in the antiferromagnetic state with its spin axis parallel to the c-axis. The Ni L3,2-edge X-ray linear dichroism results indicate that above TSO, the Ni 3d eg electrons preferentially occupy the out-of-plane 3d3z2−r2 orbitals and switch to the in-plane 3dx2−y2 orbitals below TSO. The inherent distortion of the NiO6 octahedra and anisotropic nearest-neighbor Ni-O bond lengths between the c-axis and the ab-plane of NTO, followed by anomalous Debye-Waller factors and orbital-lattice in conjunction with spin-phonon couplings, stabilize the occupied out-of-plane (3d3z2−r2) and in-plane (3dx2−y2) Ni eg orbitals above and below TSO, respectively.

AC magnetic response of superconducting single crystals exhibiting a second peak on the DC magnetization curves

The strong modulation of the AC magnetic response in the magnetic field-temperature region of the DC magnetization peak effect (PE) occurring just below the DC irreversibility line (IL) of weakly pinned superconducting single crystals is well known. However, it is not yet clear if the AC magnetic signal registered at usual frequencies and amplitudes is significantly affected by the presence of the second magnetization peak (SMP) in the DC magnetic hysteresis curves, since the SMP appears in specimens with stronger pinning and is located well below the IL. We investigated the AC magnetic response of several La2−xSrxCuO4 and 122-type pnictide superconducting single crystals exhibiting a pronounced DC SMP. It was found that in the case of small demagnetization effects, the AC magnetic signal across the SMP remains in the linear regime, with no detectable distortions in the SMP range (within the high sensitivity of a Physical Property Measurement System). This indicates reduced values of the Campbell penetration depth compared with the London magnetic penetration depth. A clearly nonmonotonic, SMP-related variation has only been obtained for the DC field dependence of the out of phase component of the AC magnetic moment in the nonlinear regime. The nonlinear AC Bean regime far below the IL has been attained in the conditions of enhanced demagnetization effects (plate-like specimens in perpendicular magnetic fields).

Strongly polarized emissions from selectively controlled electric- and magnetic-dipole transitions in Er3+ ions

We demonstrate strongly polarized photoluminescence (PL) from Er3+ ions embedded in plasmonic nanocavity arrays, which was reported in our recent paper [Choi et al., Nano Lett. 16, 5191 (2016)]. The precise positioning of the Er3+ layer within the nanocavities with respect to the node and antinode of the electromagnetic field modifies the PL spectral shape and allows linearly polarized emission with a 98% degree of polarization. The observed PL is caused by a single component of the dipole moments in Er3+ emitters and by anisotropically controlled local density of states.

The Effect of Relativistic Interactions on the Spectral Characteristics of the Ground State of Carbon Monoxide

Using high-precision nonempirical methods of modern quantum chemistry, the effect of the weak relativistic interactions on the potential energy and the permanent dipole moment of the ground electronic state of the CO molecule is studied. The relativistic energy is calculated by the following three optional methods: within the first-order perturbation theory using the Cowan–Griffin operator containing the sum of the mass-velocity and Darwin corrections, within the framework of the approximate Douglas–Kroll–Hess scalar Hamiltonian, and the most rigid “four-component” relativistic Dirac–Coulomb–Gaunt Hamiltonian. The relativistic correction obtained by different methods agrees within a few percents and equals about 55–60 cm–1 in the region of an equilibrium internuclear distance of $${{R}_{e}} = 1.128$$ A. The addition of the relativistic correction decreases the equilibrium bond length by about 0.0002 A. The magnitude of the Lamb shift estimated by the semiempirical scaling of the one-electron Darwin’s term does not exceed several inverse centimeters near $${{R}_{e}}$$ . The relativistic correction to the dipole moment function is in the range from –0.001 to +0.003 D, which does not exceed 1% of the nonrelativistic component of the dipole moment.

3-Cyano thiophene-based π-conjugated mesogens: XRD and 13C NMR investigations

ABSTRACT3-Cyano thiophene-centred π-conjugated mesogens with alkoxy phenyl/biphenyl rings are synthesised by palladium acetate-catalysed direct arylation to investigate the mesophase properties and the molecular order. The synthesised mesogens mostly exhibit smectic A mesophase as confirmed by X-ray diffraction studies. Further, due to the manifestation of π-conjugated core, the mesogens exhibit photo luminescence in solution with emission maxima in the range 425–460 nm. Density functional theory and time-dependent density functional theory calculations of a representative mesogen indicate possible intramolecular charge transfer transition between the biphenyl to 3-cyanothiophene units. Despite structural simplicity, the observation of smectic A phase is attributed to location of strong dipole moment component perpendicular to the long axis of the molecules due to the presence of polar cyano group at 3-position of central thiophene ring. The 13C NMR studies are performed in mesophase and using the 13C–1H dipolar couplings determined from 2D separated local field experiment; the order parameters of central thiophene ring and side arm phenyl rings are calculated. Moreover, the order parameter ratios of thiophene and side arm phenyl rings indicate the bent–core nature of the mesogen.

Design of a calibration setup for the dynamic analysis of multi-component force and moment sensors

For the dynamic calibration of multi-component force and moment sensors, different requirements need to be considered. We describe the mechanical design process for a calibration setup of such sensors with special focus on the generation of uniaxial force and moment components in different axes, with minimized secondary loads. The design is analysed using FEM simulations and experiments.

Multicomponent force transducer calibration procedure using tilted plates

The calibration of a multicomponent force transducers (MFTs) represents a challenge in the meganewton range. In fact, the generation of transversal forces and moments is complex since a force standard machine (FSM) is only able to apply an uniaxial force. Furthermore since MFTs are composed of multi-transducers, each one dedicated to a particular component, correlations between force and moment components are possible. Therefore, a calibration system that could simultaneously generate all force/moment components and could be suitable in every FSM is needed. For this purpose, a couple of tilted plates was designed. Calibration measurements were performed on a 2 MN MFT at INRiM, LNE and PTB. Exploitation matrixes and performance indicators showed good results, unless small but not negligible correlations between MFT outputs. In particular some spurious values due to the uncertainty in the vertical force application point influenced the moment components.

Accurate force and moment measurement in spring testing machines by an integrated hexapod-shaped multicomponent force transducer

In spring testing machines, measurement of transversal forces and bending/torsion moments, as well as vertical force, is crucial for spring characterization. For this purpose, the more advanced industrial machines are typically equipped with multicomponent force transducers (MFTs), composed by different sensors each one is dedicated to a single force component. However, such assembled MTFs present unsolved technical problems, i.e. moment measurements are not performed and the periodic calibration is hard to manage. To overcome these problems, a hexapod-shaped MFT was devised and integrated into a new model of an industrial spring testing machine, thus enabling simple periodic calibrations and ensuring measurement traceability, as well as measuring the moment components. The present work deals with the performance evaluation and metrological validation of the system.

Patterns in change and balancing of aerodynamic imbalance of the low­pressure axial fan impeller

We have studied patterns in the change and balancing of aerodynamic imbalance of the impeller for the axial fan of type VO-06-300 (Ukraine). We have found the aerodynamic imbalance of the impeller caused by mounting one blade: – at a different angle of attack; – with a violation in the step uniformity; – not perpendicularly to the longitudinal axis of the impeller; – with all three of the above-mentioned errors present at once. We have estimated a change in the aerodynamic imbalance due to change in air density. We estimated the influence of air temperature, altitude above sea level, atmospheric pressure, on air density and aerodynamic imbalance. It was established that a different angle of attack and a violation of the perpendicularity give rise to the dynamic imbalance in which the moment component is an order of magnitude larger than the static component. A violation of the step uniformity gives rise only to the static component, which is in the plane of the impeller. Among the errors considered, the most undesirable one relates to mounting a blade at a different angle of attack. At such an error, aerodynamic imbalance is 6‒8 times larger than that due to other errors. A ±4-degree change in the angle of attack of a single blade in the impeller can degrade the accuracy of balancing of the impeller to the accuracy class G 6.3 at a frequency of 1,500 rpm, or G 16 ‒ at 3,000 rpm. It was established that the ordinary and aerodynamic imbalances can be balanced at the same time. It is appropriate to carry out dynamic balancing in two correction planes. It is possible to conduct balancing by rotor mass correction or using passive auto-balancers. A specific example is used to demonstrate the procedure for taking into consideration the aerodynamic imbalance in differential equations of motion of the axial fan. In accordance with the procedure, the aerodynamic imbalance components are added to the respective components of the ordinary imbalance. The results obtained are applicable when designing and manufacturing low-pressure axial fans. Employing them would improve vibration characteristics of the specified fans.