Electromagnetic Moments Research Articles

Modification of tensor force in 0p-shell model effective interaction

In many shell model interactions, the tensor force monopole matrix elements often retain systematic trends originating in the bare tensor force. However, in this work, we find that Isospin [Formula: see text] tensor force monopole matrix elements of widely used p-shell effective interaction CK(8–16) do not share these systematic. We correct these discrepancies by modifying [Formula: see text] tensor force two-body matrix elements (TBMEs) of CK(8–16) by the analytically calculated tensor force TBMEs. With some additional modification of single-particle energies and TBMEs, the revised effective interaction is named as CKN. The effective interaction CKN has been tested for the calculations of p-shell nuclei of normal parity states from various physics viewpoints such as excitation spectra, electromagnetic moments, and electromagnetic and Gamow–Teller (GT) transitions. The obtained results are found to be satisfactory with respect to the experimental results.

Anomalous electromagnetic moments of τ lepton in γγ → τ+τ− reaction in Pb+Pb collisions at the LHC

We discuss the sensitivity of the γγ→τ+τ− process in ultraperipheral Pb+Pb collisions on the anomalous magnetic (aτ) and electric (dτ) moments of τ lepton at LHC energies. We derive the corresponding cross sections by folding the elementary cross section with the heavy-ion photon fluxes and considering semi-leptonic decays of both τ leptons in the fiducial volume of ATLAS and CMS detectors. We present predictions for total and differential cross sections, and for the ratios to γγ→e+e−(μ+μ−) process. These ratios allow to cancel theoretical and experimental uncertainties when performing precision measurements at the LHC. The expected limits on aτ with existing Pb+Pb dataset are found to be better by a factor of two comparing to current best experimental limits and can be further improved by another factor of two at High Luminosity LHC.

Optimization of the magnetic system of a VR machine for traction electric drives in agriculture

The purpose of this article is to optimize a VR machine for traction electric drives in agriculture, as well as to identify its advantages and disadvantages, to compare an electric drive based on a test machine with an asynchronous electric drive of the same size. The optimal ratio of the elements of the magnetic system of the electromechanical converter based on the VR machine. It is shown that the overload capacity of an electric drive with a VR machine is about 25%. The specific electromagnetic moment of the studied machine is 30% higher than the corresponding indicator of an asynchronous machine of the same size in the nominal operating mode. The disadvantage of this machine is its low power factor, only 7%. This is due to the small ratio of conductivities along the longitudinal and transverse axes of the machine due to the large number of stator and rotor teeth. The problem is solved by introducing additional DC or AC windings on the stator. It is shown that a change in the air gap significantly affects the specific moment. Only by reducing by 2 times the air gap managed to increase the moment by 48%.

New Approaches to Designing of Electrical Machines for Modern Controlled AC Electric Drives

In this paper, we consider new possibilities realized in alternating current electric machines that are designed for controlled electric drives and powered by semiconductor frequency converters. We concentrate on the possibility of improving the technical and economic performance of the system by taking into account the combined work of the semiconductor converter and the engine under development. The design of asynchronous electric machines for a semiconductor converter is shown to allow significantly improve its energy performance and expand the control range in terms of electromagnetic moment. The possibility of improving the mass–dimension parameters of synchronous machines operating in frequency-controlled systems is substantiated. We show that it is possible for these machines to exclude completely loss from synchronism. We established that synchronous reluctance machines can have specific indices close to those of asynchronous motors, and they realize a significantly larger overload torque in this case. Calculated methods for the synthesis of asynchronous electric drives that were successfully tested in the development of a series of main drives of the D423 drilling rig are proposed. These electric machines were designed for mechanisms with a fanlike load (mud pump) and with an active reluctance torque (winch drive). A synthesis method for the SRMTD synchronous reluctance engines that were tested on an engine for a cold pipe rolling mill is developed.

Structural trends in atomic nuclei from laser spectroscopy of tin

Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2+, 3/2+, and 11/2− states in 117–131Sn, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling.

Rejecting the Majorana nature of dark matter with electron scattering experiments

Assuming that Dark Matter (DM) is made of fermions in the sub-GeV mass range with interactions dominated by electromagnetic moments of higher order, such as the electric and magnetic dipoles or the anapole moment, we show that direct detection experiments searching for atomic ionisation events in xenon targets can shed light on whether DM is a Dirac or Majorana particle. Specifically, we find that between about 45 (120) and 610 (1700) signal events are required to reject Majorana DM in favour of Dirac DM with a statistical significance corresponding to 3 (5) standard deviations. The exact number of DM signal events corresponding to a given significance depends on the relative size of the anapole, magnetic dipole and electric dipole contributions to the expected rate of DM-induced atomic ionisations under the Dirac hypothesis. Our conclusions are based on Monte Carlo simulations and the likelihood ratio test. While the use of asymptotic formulae for the latter is standard in many applications, here it requires a non-trivial extension to the case where one of the hypotheses lies on the boundary of the parameter space. Our results constitute a solid proof of concept about the possibility of using direct detection experiments to reject the Majorana DM hypothesis when the DM interactions are dominated by higher-order electromagnetic moments.

Piece‐wise control of constant electromagnetic moments for spacecraft self‐ and soft‐docking exploiting dynamics conservation

AbstractInter‐spacecraft electromagnetic proximity operation has many potential advantages, such as no propellant consumption and plume contamination, while providing high‐precision, continuous, reversible, synchronous, and non‐contacting control capability. In addition, with constant magnetic moment actuation, the inter‐spacecraft electromagnetic force is, in essence, a kind of conservative force and has dynamics conservation. This yields specific and targeted evolvement laws of relative motion among these actuated magnetic dipoles. Exploiting these properties, spacecraft self‐ and soft‐docking could be achieved with proper piece‐wise constant magnetic moments design, which not only improves control precision, but also reduces the demand of relative motion measurement and simplifies docking controller design. Aiming at electromagnetic spacecraft self‐ and soft‐docking controller design, this paper uses dynamic modeling and dynamics conservation analysis to derive the specific evolvement laws of relative motion between the actuated magnetic dipoles first, and then utilize these laws and corresponding dynamics conservation to design the piece‐wise constant electromagnetic moments.

A Control System of an Electric Drive with a Synchronous Reluctance Machine with Independent Excitation

A method for adjusting frequency-regulated drives with the synchronous reluctance machine with independent excitation is proposed using the KhPT-250 cold tube reducing mill and traction drive of a Gazelle-Next electric vehicle as example; the method consists in independent adjustment of the phase currents with the subsequent identification of parameters of the control object by methods of frequency identification. It has been shown that, with independent control of the excitation currents and the anchor reaction, the cross links between phase current control loops can be neglected, which can be accounted for by the large bandwidth of the uniform pass-through frequency of the phase current control loops and the weak influence of phase windings located in the interpolar gap on the operation of the phase windings that currently located above the pole. It has been shown that when the drive operates at high speeds, a significant decrease in the proportionality coefficient between the magnitude of the electromagnetic moment and current is observed, which is explained by the finite speed of the phase current control loop. When adjusting the electric drive control system with dual-zone speed control, it has been suggested to introduce a correction for the anticipatory effect of the phase current in order to provide a constant relationship between the anchor component of phase current and the magnitude of electromagnetic moment.

An upgrade of the UoA nuclear electromagnetic moments database

A web–based database of nuclear electromagnetic moments data has been created and hosted online at the University of Athens since 2012. In this work, we report on an update which has focused on syncing spectroscopic information, electric quadrupole and magnetic dipole moments with the ENSDF database and literature values. A new feature is the incorporation of nuclear charge radii values obtained after 2015. Additionally, instructions of how to use the database, alongside with annonations and abbreviations, are presented.

TRANSITION PROCESSES IN ELECTROMECHANICAL TRANSMISSION WITH A RESILIENT-ELASTIC COUPLING

Driving systems for hybrid cars and electric vehicles equipped with electric motors have different structures and characteristics. In the vast majority of hybrids, depending on the driving mode, the torque on the wheels of the car can be generated separately by both the internal combustion engine and the electric motor, or by working together. Based on the research results it is established that at the moment of starting the electric motor, the torque in the transmission sections steeply increases to 17 N•m, and for about 1 s decreases to the value of 7 N•m. In the period from 4 to 5.5 s, the torque increases to 14 N•m, which is explained by the overcoming of the inertial load during acceleration of the driven weight, and rapidly decreases to the value of 4 N•m, which corresponds to the consolidated moment of resistance to movement. The electromagnetic moment of electric motor thus also increases steeply in the initial stage of starting the motor up to 66 N•m and after 1 s decreases to the value of 15 N•m. After 5.5 s there is an increase in the moment to the value of 66 N•m and after 5.8 s it stabilizes and ranges from -6 to 22 N•m. In turn, the calculations for an electromechanical transmission equipped with a resilient-elastic coupling showed that the maximum torque in its sections Т2 during the start-up period decreased to 9 N•m, and the acceleration time to a steady turning velocity of the driven weight slightly increased to 6.8 s. The torque that occurs in the transmission sections during acceleration to a steady velocity does not exceed 13 N•m. The torque in the resilient-elastic coupling sections during the start-up period does not exceed 10 N•m, and its value, upon reaching the steady motion of the driven weight, is slightly less than 5 N•m. Peak torque in the resilient-elastic coupling sections Т1 reaches 22 N•m, while in the transmission Т2 it is 13 N•m, which confirms the efficiency of resilient-elastic coupling operation. Thus, the use of resilient-elastic coupling in an electromechanical transmission can reduce the amplitude of the torque in the drive sections during the start-up period by about 1.9 times, as compared to the amplitude of the torque without resilient-elastic coupling, and reduce the peak torque of the transmission sections by 1.7 times. Keywords: asynchronous electric motor, dynamic model, mathematical model, simulation model, torque.

Reggeized model for γp → ρ− Δ++(1232) photoproduction

A model for the reaction is presented with the t-channel π + ρ exchanges reggeized to describe the reaction up to high energies. Gauge invariance of ρ exchange is discussed in connection with the convergence of the reaction cross section at high energies. The roles of electromagnetic (EM) multipole moments of Δ++ baryon and ρ−meson are analyzed in total and differential cross sections and spin density matrix elements. Photon polarization asymmetry Σ is predicted for the measurement of electromagnetic moments of ρ−and Δ++.

Radiative corrections for the decay varSigma ^0rightarrow varLambda e^+e^-

Electromagnetic form factors serve to explore the intrinsic structure of nucleons and their strangeness partners. With electron scattering at low energies the electromagnetic moments and radii of nucleons can be deduced. The corresponding experiments for hyperons are limited because of the unstable nature of the hyperons. Only for one process this turns to an advantage: the decay of the neutral Sigma hyperon to a Lambda hyperon and a real or virtual photon. Due to limited phase space the effects caused by the Sigma-to-Lambda transition form factors compete with the QED radiative corrections for the decay varSigma ^0rightarrow varLambda e^+e^-. These QED corrections are addressed in the present work, evaluated beyond the soft-photon approximation, i.e., over the whole range of the Dalitz plot and with no restrictions on the energy of the radiative photon.

Toroidal Moments Probed by Electron Beams

Toroidal moments have recently attracted attentions as an individual class of moments, by expanding the vector potential and decomposing the third component into toroidal moments and magnetic quadrupoles. Toroidal moments sustain peculiar time-space symmetry relations and are known as hybrid modes, which can be only understood by including retardation effects. Here, we outline our recent attempts to realize toroidal moments in void oligomeric meta-molecules. These structures are investigated experimentally using electron energy-loss spectroscopy and numerically using finite-difference time-domain method. We discuss about various toroidal moments supported by these structures, the role of symmetry and topology in excitation of these moments, the radiation from electron-induced toroidal moments resolved by cathodoluminescence spectroscopy, and finally hybridization of toroidal moments in coupled oligomers. Our findings outline the necessity of including toroidal moments within the classes of electromagnetic moments, despite the current discrepancy about their significance.

Experimental research of the three-phase physical model of the magnetic field inductor in the working mode when processing bulk material

A physical model of a three-phase magnetic field inductor with a cylindrical working chamber is presented for conducting its experimental research in the working mode. Results. A frame from the shot video is provided, confirming that the ferromagnetic elements of a certain shape in the operating mode are oriented along the lines of force of the magnetic field during its rotation. This means that the resulting electromagnetic moment, by analogy with synchronous machines, will be reactive, the principle of operation of the inductor will correspond to the principle of operation of a synchronous jet motor. The dependences of the electric values of the magnetic field inductor in the steady-state operating mode are presented, depending on the volumetric coefficient of the chamber filling with ferromagnetic elements. Originality. Photos of the material before and after processing it in the inductor are presented. Practical value. Practical recommendations are given that can be taken into account during further refinement of experimental studies.

Comparative analysis of electromagnetic parameters and power interactions in a large turbogenerator in asymmetric load mode

Purpose. Presentation of the results of a rotating magnetic field numerical calculation of a turbogenerator in an asymmetric load mode within its standard limitations. Methodology. The calculation of the rotating magnetic field at full rotation of the rotor is carried out by the finite element method according to the FEMM program. Calculations are automated by controlling the program using Lua script. Results. Calculations are carried out for a 325 MW turbogenerator. The temporal functions of magnetic flux linkage and the corresponding EMF of the rotor winding and phase stator windings were obtained, the power processes in the ferromagnetic core of the stator of the turbogenerator were analyzed, namely the force actions on the teeth and on the core as a whole, the pulsations of the electromagnetic moment and the time functions of its variable component. For a more detailed illustration of the results, similar calculations are performed for the symmetric load of the turbogenerator. Practical value. Analysis of the operation of the TG with an unbalanced load showed problems of power and electromagnetic nature. It is shown that the time functions of the forces acting on the teeth of the stator core are almost the same as those with a symmetrical load, but the compressive forces acting on the core have increased. It is determined that the pulsations of the electromagnetic moment reach 17% of its average value.

GEOMETRIC AND ELECTROPHYSICAL PARAMETERS OF ARMATURE WINDING OF ELECTROMECHANICAL CONVERTER OF INERTIAL ENERGY STORAGE FOR SUBURBAN TRAINS

Purpose. To establish analytical expressions of machine constant and electromagnetic parameters for a specific circuit of the armature winding of an electromechanical converter of an inertial energy storage device, which is a DC electric machine with a semiconductor switch and excitation from permanent magnets. Methodology. For research the theory of electrical circuits is used to create a mathematical model of the processes of electromechanical energy conversion in an inertial storage device. The plots method is used to find the mutual inductance of the armature winding coils, which are presented in the form of infinitely thin single-turn contours of rectangular shape, located in three-dimensional space. Results. Mathematical models of the processes of electromechanical energy conversion in an inertial storage device are obtained reflecting the relationship between the exchange energy and drive power with geometric and electrophysical parameters of both the energy accumulator and the system of its electromechanical converter. A connection of the parameters of machine constant, active and inductive resistances with the configuration, wiring diagram and the geometric dimensions of the armature winding has been established. The wiring of sections in the phase of the armature winding depends on the required value of the voltage and current of the machine. The possibility of regulating the voltage of the drive by switching on and off the working phases of the system of electromechanical converter, as well as by changing the angle of the load is shown. Originality. Mathematical models are obtained that relate the indicators of the energy of exchange and the power of the drive to the geometrical and electro physical parameters of both the energy accumulator and the system of its electromechanical converter. A feature of these models is operating with an average value of induction and machine constants when determining the electromotive force and electromagnetic moment. Practical value. Recommendations are developed for determining the machine constant and electromagnetic parameters of electromechanical inertial energy storage devices. This allows to evaluate the properties of devices of this type in the modes of storage and delivery of energy during their operation on board the rolling stock.

Engineering of Light Electric Commercial Vehicle

The paper describes the process and results of the development of the light commercial electric vehicle. In order to ensure maximum energy efficiency of the developed vehicle the key parameters of the original electric motor. The article also presents the results of power electronic thermal calculation. For the mathematical model of the vehicle, the driving cycle parameters of the electric platform were determined in accordance with UNECE Regulations No 83, 84. The driving cycle was characterized by four successive urban and suburban cycles. The mathematical model also takes into account the time phases of the cycle, which include idling, vehicle idling, acceleration, constant speed movement, deceleration, etc. The model of the electric part of the vehicle was developed using MatLab-Simulink (SimPowerSystems library) in addition to the mechanical part of the electric car. The electric part included the asynchronous electric motor, the motor control system and the inverter. This model at the output allows to obtain such characteristics of the electric motor as currents, flows and voltages of the stator and rotor in a fixed and rotating coordinate systems, electromagnetic moment, angular speed of rotation of the motor shaft. The developed model allowed to calculate and evaluate the performance parameters of the electric vehicle. Technical solutions of the electric vehicle design were verified by conducting strength calculations. In conclusion, the results of field tests of a commercial electric vehicle are presented.

Laser-cooled polyatomic molecules for improved electron electric dipole moment searches

Doppler and Sisyphus cooling of 174YbOH are achieved and studied. This polyatomic molecule has high sensitivity to physics beyond the Standard Model and represents a new class of species for future high-precision probes of new T-violating physics. The transverse temperature of the YbOH beam is reduced by nearly two orders of magnitude to < 600 μK and the phase-space density is increased by a factor of > 6 via Sisyphus cooling. We develop a full numerical model of the laser cooling of YbOH and find excellent agreement with the data. We project that laser cooling and magneto-optical trapping of long-lived samples of YbOH molecules are within reach and these will allow a high sensitivity probe of the electric dipole moment of the electron. The approach demonstrated here is easily generalized to other isotopologues of YbOH that have enhanced sensitivity to other symmetry-violating electromagnetic moments.

Digital twin of mechatronic drive based on the optimal control model of BLDC motor

This paper presents a digital twin of a mechatronic drive based on a brushless DC (BLDC) motor model based on a nonlinear discrete optimal control model. Some parameters of a BLDC motor, such as resistance and inductance of windings, magnetic flux, viscous friction coefficient in bearings, angular velocity and electromagnetic moment, can change due to both degradation of structural elements and external forces. Simulation by a complete enumeration of the values of the parameters of the mechatronic device with a certain step will make it possible to adapt the program of the control device to changing operating conditions according to the criterion of minimizing the control energy by changing the parameters of the state matrices and control of the digital twin. As a result, the accuracy of the movement of the mechatronic device along the given trajectory will increase due to the greater correspondence of the control parameters to the real object.

Comparison of Designs of a Valve-Inductor Motor of an Electric Spindle Drive

When designing electric machines, in particular, the valve-inductor motor of the electric spindle drive, there is a need to compare several designs of such machines in order to choose the most rational one. Based on the given initial data and preliminary calculations, two design variants of the engine were selected: three-phase and five-phase. For each variant, the FEMM v 4.2 software package has been used to calculate optimal geometric ratios based on the maximum of the average moment value. Then, for the optimal variants of a three-phase and five-phase machine, calculations of the voltage, current, and flow coupling of the stator phase, as well as the electromagnetic moment, were performed. It is shown that in a five-phase electric machine, the total electromagnetic moment has several times lower pulsations compared to the three-phase version.