Torsion Field Research Articles

An analytical model for predicting the extrusion force for the torsion extrusion process of metals

Torsion extrusion (TE) method as a severe plastic deformation (SPD) process can effectively refine the microstructures and improve the mechanical properties of materials. Accurate and rapid prediction of the extrusion force in the process of TE is an important problem in industry. This paper proposed an analytical model using upper bound method (UBM) for predicting the extrusion force in the TE process. The kinematically admissible velocity field is established based on a continuous spherical extrusion velocity field coupled with a torsional velocity field constrained in a conical die. The torsional angular velocities along the radial and axial directions are assumed with quadratic and cubic function, respectively, due to the radial and axial nonlinearity of torsional velocity in the deformation zone. In addition, considering its complexity, the shape of the deformation zone is mapped to a rectangular zone. By establishing the torsional velocity field in the mapped zone, the torsional velocity field of the deformation zone is obtained according to the mapping relation. The UBM model is validated by comparing the predicted extrusion force with the simulation results obtained from the finite-element method (FEM). Moreover, the influences of the friction factor, reduction ratio and die angle on the extrusion force were investigated as well.

Особенности структуры потенциального поля плазмиды pPF1 и их влияние на характер движения нелинейных конформационных возмущений – кинков

In this work, mathematical modeling methods are used to study the features of the dynamics of the nonlinear conformational perturbations, kinks, in the pPF1 plasmid. The motion of kinks is considered as the motion of quasiparticles in the potential field of the plasmid. The behavior of such quasiparticles is largely determined by the type and nature of this field. To simulate the movement of the kink along the pPF1 plasmid, the McLaughlin-Scott equation was used. Using the quasi-homogeneous approximation and the block method, the energy profile of the potential field of the pPF1 plasmid was calculated and 2D kink trajectories were constructed in the region located between the genes of the Egfp and mCherry fluorescent proteins, taking into account the effects of dissipation and exposure to a constant torsion field. It was shown that there are threshold values of the torsion field, below and above which the behavior of the kink changes significantly: there is a transition from the cyclic motion of the kink inside the region located between the genes of the fluorescent proteins Egfp and mCherry to the translational motion and exit from this region. Threshold values have been estimated. It was shown that they depend on the nature of the energy profile near the region located between the genes of the fluorescent proteins Egfp and mCherry.

Probing Nieh-Yan anomaly through phonon dynamics in the Kramers-Weyl semimetals of chiral crystals

Nieh-Yan anomaly describes the non-conservation of chiral charges induced by the coupling between Dirac fermions and torsion fields. Since the torsion field is beyond general relativity, this effect remains hypothetical and its relevance to our universe is unclear in the context of high-energy physics. In this work, we propose that the phonons can induce a torsion field for the Kramers-Weyl fermions through electron-phonon interaction in a non-magnetic chiral crystal, thus leading to the occurrence of the Nieh-Yan anomaly in this condensed matter system. As a consequence, the Nieh-Yan term can strongly influence the phonon dynamics and lead to the helicity of acoustic phonons, namely, two transverse phonon modes mix with each other to form a circular polarization with a non-zero angular momentum at a finite phonon momentum and the phonon angular momentum reverses its sign for opposite momenta due to time reversal symmetry. The phonon helicity can be probed through measuring the total phonon angular momentum driven by a temperature gradient.

Axial-torsional mode correlation analysis of a drill string system with non-smooth characteristics

Axial-torsional coupling vibrations are dangerous and complex vibrations that can cause abnormal working conditions in the drilling system. Therefore, the vibration mode correlation is essential in the dynamic analysis of the response complexity of the system to reduce the vibration risk level. In this paper, an axial-torsional lumped parameter model with 5-DOF (degrees of freedom) is proposed to investigate the axial-torsional mode correlation of a drill string system with non-smooth characteristics. Numerical simulations are carried out by using the 4th-5th order Runge-Kutta method with adaptive time steps, and the simulation results are compared and verified by the 5-DOF torsional lumped parameters model and field measurement data. It also performs time domain, frequency domain, and correlation coefficient analysis. The results reveal the mode shape and correlations of an axial-torsional mode in coupled vibrations with and without a bit-bounce. Bit-bounce and stick-slip coupling vibration can be produced by increasing the rotary table speed. The torsional angular velocity of the proposed model is smaller than that of the comparative model, which is in good agreement with the field data.

Diffusion in the presence of a chiral topological defect

We study the diffusion processes of a real scalar field in the presence of the distorsion field induced by a chiral topological defect. The defect modifies the usual Euclidean background geometry into a non-diagonal Riemann-Cartan geometry characterized by a singular torsion field. The new form of the diffusion equation is established and the scalar field distribution in the vicinity of the defect is investigated numerically. Results show a high sensitivity to the boundary conditions. In the transient regime, we find that the defect vorticity generates an angular momentum associated to the diffusion flow and we discuss its main properties.

Spin Wave and Soliton Wave Activity as Well as Biocomputer Imulation in Visual Perception

All the material presented in this thesis as well as the author’s implications/conclusions prove that a living organism can be perceived as a complex electronic device similar to technical devices, whereas biological materials (proteins, DNA, RNA) - as components of electronic devices. These arguments allow us to state that a biological system can be considered to be a quantum computer that functions on the basis of entangled quantum states and optoelectronic phenomena. Melanin and neuromelanin are involved in the central control of all biological, physiological and psychological processes. Numerous modular communication systems and signalling pathways that transmit signals into cells are generated under the influence of light. Melanin and neuromelanin function as multireceptors of a full range of electromagnetic, acoustic, and soliton waves, torsion fields and bioplasma, which does not receive so much information as the senses do, but receive it constantly. The role of photoreceptors, receptors of hearing and touch is limited to a single reception of a stimulus, whereas melanin and neuromelanin play an integrative function, combining stimulus elements into a whole, namely combining movement with space and time, sound with light, space and time. From the psychological point of view, melanin and neuromelanin are responsible for the entire process of adaptation to the environment, mental development, the development of attention and perceptual experience, which, together with an increase in melanin and neuromelanin, acquire better sharpness and quality. Bioplasma controls these processes.

A Possible Explanation of Dark Matter and Dark Energy Involving a Vector Torsion Field

A simple gravitational model with torsion is studied, and it is suggested that it could explain the dark matter and dark energy in the universe. It can be reinterpreted as a model using the Einstein gravitational equations where spacetime has regions filled with a perfect fluid with negative energy (pressure) and positive mass density, other regions containing an anisotropic substance that in the rest frame (where the momentum is zero) has negative mass density and a uniaxial stress tensor, and possibly other “luminal” regions where there is no rest frame. The torsion vector field is inhomogeneous throughout spacetime, and possibly turbulent. Numerical simulations should reveal whether or not the equations are consistent with cosmological observations of dark matter and dark energy.

Probing a dark gauge boson via the Einstein-Cartan portal

Einstein-Cartan gravity which is an alternative formulation of general relativity introduces new degrees of freedom contained in the torsion field which encodes the torsion feature of spacetime. Interestingly, the torsion field couples to all fermions through its axial-vector mode with a universal coupling $\eta=1/8$ which is possible to change under the quantum effects. We argue that Einstein-Cartan gravity provides a significant portal to probe $A'$ dark gauge boson which resides in dark sector existing as an invisible world parallel to our own and couples to the standard model (SM) particles through only the kinetic mixing. For the (very) small kinetic mixing, searches for the $A'$ from Drell-Yan processes are insensitive due to the suppressed production cross-section and the considerable SM backgrounds. However, through the mediation of torsion field the $pp$ collisions produce dark-sector fermions which would significantly produce the $A'$ due to unsuppressed dark gauge coupling. We explore the potential production modes of the $A'$ through bremsstrahlung off dark-sector fermion and the cascade decays. Einstein-Cartan gravity suggests the torsion mass $\gtrsim\mathcal{O}(4)$ TeV for $\eta$ varying around the classical value since the present scenarios would tend to produce the $A'$ with the high boost and large missing transverse momentum from dark-sector fermions where the SM backgrounds are low. On the other hand, the $A'$ search via Einstein-Cartan portal can reach even for the signal events to be not large and is also sensitive to the (very) small kinetic mixing as long as the decay channels of the $A'$ to dark-sector particles are inaccessible.

Plebański-Demiański solutions with dynamical torsion and nonmetricity fields

We construct Plebański-Demiański stationary and axisymmetric solutions with two expanding and double principal null directions in the framework of Metric-Affine gauge theory of gravity. Starting from the new improved form of the metric with vanishing cosmological constant recently achieved by Podolský and Vrátný, we extend this form in the presence of a cosmological constant and derive the conditions under which the physical sources of the torsion and nonmetricity tensors provide dynamical contributions preserving it in Weyl-Cartan geometry. The resulting black hole configurations are characterised by the mass, orbital angular momentum, acceleration, NUT parameter, cosmological constant and electromagnetic charges of the Riemannian sector of the theory, as well as by the spin and dilation charges of the torsion and nonmetricity fields. The former is subject to a constraint representing a decoupling limit with the parameters responsible of axial symmetry, beyond which the geometry of the space-time is expected to be corrected.

Galactic dynamo seeds and black hole singularities driven by Einstein–Cartan QCD walls

Torsion spin polarised wall solution of Einstein–Cartan equations as torsion defects (Garcia de Andrade, Ann Phys 432 (2021)) where spin is distributed orthogonally to the wall has recently been obtained. Moreover, torsional inflating defect [Class and Quantum Gravity, 16 (1999) 2097] in the form of a dilatonic domain wall has also been found. Our goal in this paper is to obtain thin torsion wall solutions as teleparallel and Riemann–Cartan (RC) spacetime walls, with Einstein–Cartan stress–energy tensor, similar to Kalb–Ramond torsion fields. In thin teleparallel wall, we show that torsion is proportional to a time Dirac delta function which possesses a time singularity at the wall like Big Bang and black hole GR ones. This magnetic field has a torsional contribution of BQCD∼1017G in RC walls, which is suitable for dynamo amplification from a seed field of Bseed∼1012G as Big Bang Nucleosynthesis (BBN). From QCD cosmic time scale of tQCD∼10−6s torsion of the order of J0∼10−11cm−1 is obtained. From a 1 MeV torsion and seed field of Bseed∼10−32G, found by Barrow et al [PRD] in the framework of general relativity (GR) which is suitable to seed galactic dynamo field. In this case a domain wall magnetic field of BDW∼10−28G which is stronger, and more suitable as a galactic dynamo seed, is obtained. Magnetic field seed of 10−14G, quite close to orders of magnitude of O(10−15−10−18G) obtained by Atrayed et al. (EPJC (2018) 78: 1027) on a torsionless GR domain wall, generates a wall (DW) magnetic field of order of BDW∼1018G obtained at 1 kpc scales. These similarities between GR results and teleparallel one were expected due to the fact that the teleparallel theory of gravity considered in this paper is the teleparallel equivalent to GR or (TEGR). Chiral dynamos in dilatonic conformally flat metric are also discussed.

Torsion, energy magnetization, and thermal Hall effect

We study the effective action of hydrostatic response to torsion in the absence of spin connections in gapped $(2+1)$-dimensional topological phases at low temperatures. In previous studies, a torsional Chern-Simons term with a temperature-squared (${T}^{2}$) coefficient was proposed as an alternative action to describe the thermal Hall effect with the idea of balancing the diffusion of heat by a torsional field. However, the question remains whether this action leads to a local bulk thermal response that is not suppressed by the gap. In our hydrostatic effective action, we show that the ${T}^{2}$ bulk term is invariant under variations up to boundary terms considering the geometry dependence of local temperature, which precisely describes the edge thermal current. Furthermore, there are no local boundary diffeomorphism anomalies or bulk inflow thermal currents at equilibrium, and also there is no edge-to-edge adiabatic thermal current pumping upon changing the gravitational background. These results are consistent with exponentially suppressed thermal current for gapped phases.

DNA kinks behavior in the potential pit-trap

<abstract> <p>For better understanding the role of dynamic factors in the DNA functioning, it is important to study the internal mobility of DNA and, in particular, the movement of nonlinear conformational distortions -kinks along the DNA chains. In this work, we study the behavior of the kinks in the pPF1 plasmid containing two genes of fluorescent proteins (EGFP and mCherry). To simulate the movement, two coupled nonlinear sine-Gordon equations that describe the angular oscillations of nitrogenous bases in the main and complementary chains and take into account the effects of dissipation and the action of a constant torsion field. To solve the equations, approximate methods such as the quasi-homogeneous approximation, the mean field method, and the block method, were used. The obtained solutions indicate that two types of kinks moving along the double strand can be formed in any part of the plasmid. The profiles of the potential fields in which these kinks are moving are calculated. The results of the calculations show that the lowest energy required for the kink formation, corresponds to the region located between the genes of green and red proteins (EGFP and mCherry). It is shown that it is in this region a pit trap is located for both kinks. Trajectories of the kinks in the pit-trap and nearby are constructed. It is shown that there are threshold values of the torsion field, upon reaching which the kinks behavior changes dramatically: there is a transition from cyclic motion inside the pit-trap to translational motion and exit from the potential pit-trap.</p> </abstract>

Rotating Kerr-Newman space-times in metric-affine gravity

We present new rotating vacuum configurations endowed with both dynamical torsion and nonmetricity fields in the framework of Metric-Affine gauge theory of gravity. For this task, we consider scalar-flat Weyl-Cartan geometries and obtain an axisymmetric Kerr-Newman solution in the decoupling limit between the orbital and the spin angular momentum. The corresponding Kerr-Newman-de Sitter solution is also compatible with a cosmological constant and additional electromagnetic fields.

Interference effects and modified Born rule in the presence of torsion

The propagation of nonrelativistic excitations in material media with topological defects can be modeled in terms of an external torsion field modifying the Schr\"odinger equation. Through a perturbative approach, we find a solution for the wave function which gives corrections in the interference patterns of the order of 0.1 \AA{}, for a possible experimental setup at atomic scales. Finally, we demonstrate how this geometric, but effective, approach can indeed accommodate a probabilistic interpretation of the wave function although the perturbative theory is nonunitary.

Quantum Hydrodynamics of Spinning Particles in Electromagnetic and Torsion Fields

We develop a many-particle quantum-hydrodynamical model of fermion matter interacting with the external classical electromagnetic and gravitational/inertial and torsion fields. The consistent hydrodynamical formulation is constructed for the many-particle quantum system of Dirac fermions on the basis of the nonrelativistic Pauli-like equation obtained via the Foldy–Wouthuysen transformation. With the help of the Madelung decomposition approach, the explicit relations between the microscopic and macroscopic fluid variables are derived. The closed system of equations of quantum hydrodynamics encompasses the continuity equation, and the dynamical equations of the momentum balance and the spin density evolution. The possible experimental manifestations of the torsion in the dynamics of spin waves is discussed.

Geometrical aspects of hypermagnetic field interactions

We investigate the role of a dynamical torsion field coming from a geometrical non-Riemannian model. This model is reminiscent of a generalized Born-Infeld theory and the torsion plays a fundamental role trough its Hodge dual: the pseudovector This contains axion, Kalb-Ramond 2-form and physical observables of macroscopic character. An emergent interaction Lagrangian arises from the model and it is compared with a superstring inspired one taken from Bamba Kazuharu et al., Phys. Lett. B, 664 (2008) 154 pulling out several important consequences in favor of our proposal, as the possibility of establishing a clear connection between the change of the CMB polarization plane and the anomalous current .

On Totally Split Primes in High-Degree Torsion Fields of Elliptic Curves

Abstract Analogously to primes in arithmetic progressions to large moduli, we can study primes that are totally split in extensions of ${\mathbb {Q}}$ of high degree. Motivated by a question of Kowalski we focus on the extensions ${\mathbb {Q}}(E[d])$ obtained by adjoining the coordinates of $d$-torsion points of a non-CM elliptic curve $E/{\mathbb {Q}}$. We show that for almost all integers $d$ there exists a non-CM elliptic curve $E/{\mathbb {Q}}$ and a prime $p<|\text {Gal}({\mathbb {Q}}(E[d])/{\mathbb {Q}})|= d^{4-o(1)}$, which is totally split in ${\mathbb {Q}}(E[d])$. Note that such a prime $p$ is not accounted for by the expected main term in the Chebotarev Density Theorem. Furthermore, we prove that for almost all $d$ that factorize suitably there exists a non-CM elliptic curve $E/{\mathbb {Q}}$ and a prime $p$ with $p^{0.2694} < d$, which is totally split in ${\mathbb {Q}}(E[d])$. To show this we use work of Kowalski to relate the question to the distribution of primes in certain residue classes modulo $d^2$. Hence, the barrier $p < d^4$ is related to the limit in the classical Bombieri–Vinogradov Theorem. To break past this we make use of the assumption that $d$ factorizes conveniently, similarly as in the works on primes in arithmetic progression to large moduli by Bombieri, Friedlander, Fouvry, and Iwaniec, and in the more recent works of Zhang, Polymath, and the author. In contrast to these works we do not require any of the deep exponential sum bounds (i.e., sums of Kloosterman sums or Weil/Deligne bound). Instead, we only require the classical large sieve for multiplicative characters and we apply Harman’s sieve method to obtain a combinatorial decomposition for primes.

Born-Infeld generalization: Axion and Kalb-Ramond from dynamical torsion fields

We show that in theories of gravitation based on affine geometries the torsion field, that takes a dynamical character, not only the chiral magnetic effect (CME) intervenes in the wash up of the chiral anomaly but also the chiral vortical effect (CVE) and the coupled chiral effect (CCE) coming from the hypermagnetic field interaction with the primordial plasma are crucial in a realistic physical scenario, as in the case of the early universe. We also show that the equation governing the wash up takes the form given in this paper, supplemented with the dynamical equation for the torsion vector containing the helicities and other axial couplings. The role played by the neutrinos in the interaction with the axion field in this theoretical framework is briefly discussed.

Torsional analysis of four-sided cross-sections coated by an orthotropic layer weakened by multiple defects

In this study, an analytical model for a four-sided cross-section bar reinforced by an orthotropic coating weakened by multiple cracks and cavities, under torsional loading, is presented. The main scope of the paper is to evaluate the effects of an orthotropic coating on stress intensity factors in a four-sided cross-section bar weakened by multiple arbitrarily oriented cracks and cavities. The four-sided bar and its orthotropic coating are under torsional loading governed by Saint-Venant torsional theory. The torsional stress field of the four-sided domain reinforced by the orthotropic coating containing a screw dislocation was first achieved in terms of the screw dislocation density function by using finite Fourier transform. Then, the stress field of the problem is reduced to a set of integral equations with a Cauchy singularity in the domain using the distribution dislocation method. The stress intensity factors, the torsional rigidity of the domain and the hoop stress around the cavities will be determined by the numerical solution of these singular integral equations. The stress components in the vicinity of the crack tips, and Von-Mises yield criterion are utilized to determine plastic zone size ahead of the crack tips. Finally, multiple numerical results are provided to illustrate the capability of the dislocation method in handling different cases of crack and cavity configurations and arrangements.

Analytical and meshless numerical approaches to unified gradient elasticity theory

The unified gradient elasticity theory with applications to nano-mechanics of torsion is examined. The Reissner stationary variational principle is invoked to detect the differential and boundary conditions of equilibrium along with the consistent form of the constitutive laws. An efficient meshless numerical approach is established by making recourse to the Reissner variational functional wherein independent series solution of the kinematic and kinetic field variables are proposed. Suitable forms of the coordinate functions, in terms of the Chebyshev polynomials, are introduced to fulfill a set of kinematic and higher-order boundary conditions in the elastic torsion of nano-bars with practical kinematic constraints. Torsional behavior of the unified gradient elastic bar is studied for structural schemes of applicative interest. An excellent agreement between the torsional responses of the nano-bar detected based on the established meshless method and obtained exact analytical solution is realized. The proposed meshless numerical approach is confirmed to have a fast convergence rate and an admissible convergence region in determination of the torsional rotation field with high accuracy. The introduced meshless method is demonstrated to be highly efficacious in characterizing both the softening and stiffening structural behaviors at nano-scale. The presented numerical approach therefore paves the way ahead in mechanics of nano-structures.