Current-carrying Wire Research Articles

Mass-independent scheme for enhancing spatial quantum superpositions

Placing a large mass in a large spatial superposition, such as a Schr\"odinger Cat state is a significant and important challenge. In particular, the large spatial superposition (${\cal O}(10-100)$ $\mu$m) of mesoscopic masses ($m\sim {\cal O}(10^{-14} -10^{-15})$ kg) makes it possible to test the quantum nature of gravity via entanglement in the laboratory. To date, the proposed methods of achieving this spatial delocalization are to use wavepacket expansions or quantum ancilla (for example spin) dependent forces, all of whose efficacy reduces with mass. Thus increasing the spatial splitting independent of the mass is an important open challenge. In this paper, we present a method of achieving a mass-independent enhancement of superposition via diamagnetic repulsion from current-carrying wires. We analyse an example system which uses the Stern-Gerlach effect to creating a small initial splitting, and then apply the diamagnetic repulsion method to enhance the superposition size ${\cal O}(400-600)$ $\mu$m from an initial modest split of the wavefunction. We provide an analytic and numeric analysis of our scheme.

Quality characteristics and analysis of input parameters on laser beam welding of hairpin windings in electric drives

The relevance of electric drives in individual mobility is continuously increasing. This requires the use of new manufacturing processes in automotive production. In modern stators, the so-called hairpin winding is used. The production process entails rectangular copper conductors (hairpin) to be contacted by laser beam welding. To avoid temperature peaks due to resistance heating in the current-carrying wire, a high cross-sectional area in the welding seam is required. Therefore, the pore volume must be considered. This is proven by thermographic investigations of electrically stressed hairpin connections. To optimize the welding process, effects of the previous manufacturing steps and the welding parameters themselves must be taken into account. This paper analyses systematically the impact of all translational and rotational deviations on the corresponding welding quality. The tests are performed by using a disk laser. A laser spot with a focus diameter of 170 μm is compared to a statically shaped beam, capable of distributing power in core and ring beam. As an additional parameter, the influence of oxygen content in the copper wire is investigated by using electrolytic tough pitch copper (Cu-ETP) and oxygen-free copper (Cu-OF). Furthermore, the interaction between an additional cutting step before contacting and the welding path is considered. X-ray computed tomography (CT) is used to analyse the welding quality. The main finding of the studies is the significant influence of the gap and height offset between the wire ends on the resulting cross-sectional area. In addition, a low oxygen content of the copper and the use of static beam shaping reduce weld spatters, porosity and increase process stability. Three geometries in the welding path perform better in gap bridging and cause less spatters.

Biot-Savart routines with minimal floating point error

A set of routines to compute the magnetic vector potential and magnetic field of two types of current carriers is presented. The (infinitely thin) current carrier types are a straight wire segment and a circular wire loop. The routines are highly accurate and exhibit the correct asymptotic behavior far away from and close to the current carrier. A suitable global set of test points is introduced and the methods presented in this work are tested against results obtained using arbitrary-precision arithmetic on all test points. The results are accurate to approximately 16 decimal digits of precision when computed using 64 bit floating point arithmetic. There are a few exceptions where accuracy drops to 13 digits. These primitive current carrier types can be used to assemble more complex arrangements, such as a current along a polygon (by means of defining straight wire segments from point to point along the polygon) and a multi-winding coil with circular cross-section. Reference data is provided along with the code for benchmarks with other implementations. Program summaryProgram Title: Biot-Savart Routines with Minimal Floating Point ErrorCPC Library link to program files:https://doi.org/10.17632/zcwk7zzt9y.1Developer's repository link:https://github.com/jonathanschilling/abscabLicensing provisions: Apache-2.0Programming language: C, Python, Java, FortranSupplementary material: Reference output data for all methods described in this article.Nature of problem: A common task in computational physics is to compute the magnetic field and magnetic vector potential originating from current-carrying wire arrangements. These current carriers are often approximated for computational simplicity as infinitely thin filaments following the center lines of the real current carrier. Computational methods are thus needed to compute the magnetic field and the magnetic vector potential of a single straight wire segment or a single circular wire loop as basis for modeling more complex current carrier arrangements by superposition of the current carrier primitives. A current carrier path specified by (x,y,z) coordinates can be modeled as a set of straight wire segments from point to point along the polygon describing the current carrier geometry. Closed circular wire loops are also commonly used as a proxy for a physical coil with helical windings.Solution method: Analytical expressions are derived in this work to accurately compute the magnetic field and the magnetic vector potential of a straight wire segment and a circular wire loop. The expressions consist of several special cases, which are automatically switched between depending on the location of the evaluation location in the coordinate system of the current carrier primitive. This approach guarantees that always the most accurate formulation available for a given evaluation location is used, including explicit use of simplifications in certain special cases for speed and accuracy.Additional comments including restrictions and unusual features: For most test cases, the full relative accuracy of the floating point arithmetic chosen for implementation is retained throughout the computations (16 digits of precision in the IEEE-754 binary64 implementation). There are a few exceptions where accuracy drops by up to 3 digits of precision (in the binary64 case). The provided implementations have not been optimized for speed.

Spin dynamics in quantum dots on liquid helium

Liquid He-4 is free from magnetic defects, making it an ideal substrate for electrons with long-lived spin states. When electrons are localized in quantum dots and a strong magnetic field is applied along the surface, such states may serve as qubit states. A nonuniform magnetic field from a current-carrying wire submerged into helium enables switchable spin-orbit coupling. Bringing the frequency of orbital intradot vibrations close to the Larmor frequency allows for obtaining a strong Rashba electric dipole spin resonance and efficient interdot spin coupling. The authors show that the associated spin relaxation can be made sufficiently slow, permitting high-fidelity gate operations.

Некоторые аспекты проблемы защиты птиц от поражения электрическим током на воздушных линиях электропередачи в Казахстане

Некоторые аспекты проблемы защиты птиц от поражения электрическим током на воздушных линиях электропередачи в Казахстане

Computer aided engineering of technological features of double-arc surfacing with current-carrying filler wire of contact surfaces of centrifugal pump

A technology for restoring of the contact surfaces of a centrifugal sectional pump is developed and technological requirements for the necessary equipment for its practical implementation are formulated on the basis of computer aided engineering of the technological capabilities of double-arc surfacing with a consumable electrode with a current-carrying filler wire. It is shown that the use of the proposed technology and robotic equipment for its implementation makes it possible to increase the productivity of surfacing by 1.8—2 times and provides an acceptable content of the substrate material in the deposited layer.

Встречи крупных хищных птиц в Новосибирской области, Россия

Встречи крупных хищных птиц в Новосибирской области, Россия

СНИЖЕНИЕ ГИДРАТООБРАЗОВАНИЯ ПРИ ЭКСПЛУАТАЦИИ СКВАЖИН НА ТАГУЛЬСКОМ МЕСТОРОЖДЕНИИ

The analysis of the situation of hydrate formation on the technological equipment installed on the wells of the Tagulskoye field was carried out. The necessity of using Warm Stream technology is substantiated. An economic and technical analysis of the proposed design solutions was carried out. It has been established that the replacement of the existing integrated method for combating hydrate formation with the Warm Stream and bypass valve installation will make it possible to obtain an annual cost savings of 7,011 thousand rubles at the wells of the Tagulskoye field. In addition, there will be a decrease in the number of energy consumers, a decrease in the number of current-carrying wires, and the injection of a hydrate formation inhibitor will be excluded. As a result of the implementation of the project activities, there will be a reduction in the labor costs of workers for replacing the heating cable and working with special equipment, as well as an increase in additional oil production as a result of a decrease in daily downtime of wells.

Hyperthermia temperature reduction in biomagnetic flow: Thermal transfer in Fe3O4–blood particle suspension with uniform and non-uniform effects

Magnetic hyperthermia is beneficial in cancer treatment and in the treatment of some blood vessel diseases. However, excessive temperatures may also kill healthy cells in the vicinity of a sick cell. Using magnetic nanoparticles and changing the nature of the magnetic field as required, magnetic hyperthermia may be regulated in the blood. This research examines the effects of uniform and non-uniform magnetic fields on suspensions of bio-magnetic fluid and nano-bio-magnetic fluid under hyperthermia. Blood is a diamagnetic material, and when combined with superparamagnetic Fe3O4, its thermo-mechanical characteristics are changed significantly. By manipulating the nature of the magnetic field, it is possible to raise or decrease the temperature in the flow domain of magnetic nano-fluids. A computational study of two such magnetic fields has been conducted, and their effects on the blood-based magneto nano-fluid flow in a rectangular conduit have been documented in this study using COMSOL multi-physics. Results indicate that a uniform magnetic field increases temperature only locally, but decreases the overall temperature in the domain. The non-uniform field of a current-carrying wire decreases both the local maximum and average blood temperature as field strength increases.

Combined magnetic field system for atom chips

In this paper, we have developed a combined magnetic field system to explore an alternative technical route for the generation of Bose–Einstein condensates containing numerous atoms on an atom chip. The system is characterized by the fact that the quadrupole magnetic field required by the magneto-optic trap is generated by U-shaped current-carrying wires combined with bias magnetic fields, whereas the quadrupole magnetic field adopted for the magnetic trap is generated by anti-Helmholtz coils. By fine-tuning the bias magnetic fields, the collection of atoms in the mirror MOT and the loading of the quadrupole magnetic trap can be optimized. The initial number of [Formula: see text]Rb atoms in the magnetic trap is approximately [Formula: see text], and the lifetime of the atoms is over 30 s. This scheme can facilitate the chip-surface design and is suitable for the precise manipulation of Bose–Einstein condensates near the chip surface.

Chemical analysis of carbonaceous particles inside Cu wire molten by electrical arcing

We characterized carbonaceous nanostructures, which were produced from the electrical arcing of the current-carrying Cu wires. The nanostructures are prepared in two different ways. The electrical arc is provoked by partially removing the polyvinyl chloride (PVC) insulation. In this case, PVC is exposed to electrical arcing, and it becomes the carbon structure after the arcing. In the other case, the insulation is intentionally burned, and the current-carrying Cu wire is left until they were electrically short. Thus, the carbonized PVC is exposed to electrical arcing. Our analysis of these two different carbon materials reveals that the chemical binding of carbon, the elements, the diffusion of carbon into Cu wire, and the relative distribution of the carbon are quite dissimilar. The distinctions between the carbon soot resulting from different arcing conditions can be used to decipher the cause of the fire, which has remained unsolved to date.

A study of pressure-driven flow in a vertical duct near two current-carrying wires using finite volume technique.

For heating, ventilation or air conditioning purposes in massive multistory building constructions, ducts are a common choice for air supply, return, or exhaust. Rapid population expansion, particularly in industrially concentrated areas, has given rise to a tradition of erecting high-rise buildings in which contaminated air is removed by making use of vertical ducts. For satisfying the enormous energy requirements of such structures, high voltage wires are used which are typically positioned near the ventilation ducts. This leads to a consequent motivation of studying the interaction of magnetic field (MF) around such wires with the flow in a duct, caused by vacuum pump or exhaust fan etc. Therefore, the objective of this work is to better understand how the established (thermally and hydrodynamically) movement in a perpendicular square duct interacts with the MF formed by neighboring current-carrying wires. A constant pressure gradient drives the flow under the condition of uniform heat flux across the unit axial length, with a fixed temperature on the duct periphery. After incorporating the flow assumptions and dimensionless variables, the governing equations are numerically solved by incorporating a finite volume approach. As an exclusive finding of the study, we have noted that MF caused by the wires tends to balance the flow reversal due to high Raleigh number. The MF, in this sense, acts as a balancing agent for the buoyancy effects, in the laminar flow regime.

A Microcontroller-Based Experiment to Determine the Magnetic Field Near a Straight Current-Carrying Wire

It is well known that the needle of a compass in a magnetic field deflects, and that a compass near a conductive wire carrying a stable electric current deflects its needle. The only explanation of this observation is that the current-carrying wire creates a magnetic field around it. The strength of the magnetic field at any point near the wire depends on the strength of the current and the distance from the wire. Analysis of the magnetic field created by a long straight current-carrying wire has an important place in magnetism teaching. Therefore, the aim of this study was to develop a low-cost experimental setup to collect real-time data for the analysis of the magnetic field near a long straight wire.

Superharmonic-principal parametric joint resonance and stability of an axially variable-speed moving beam between current-carrying wires

Superharmonic-principal parametric joint resonance and stability of an axially variable-speed moving beam between current-carrying wires

Research on application of LU decomposition and CG method in nonlinear iteration of transmission line finite element method

PurposeThe purpose of this study is to develop a reliable finite element algorithm based on the transmission line method (TLM) to solve the nonlinear problem in electromagnetic field calculation.Design/methodology/approachIn this paper, the TLM has been researched and applied to solve nonlinear iteration in FEM. LU decomposition method and the Jacobi preconditioned conjugate gradient method have been investigated to solve the equations in transmission line finite element method (FEM-TLM). The algorithms have been developed in C++ language. The algorithm is applied to analyze the magnetic field of a long straight current-carrying wire and a single-phase transformer.FindingsFEM-TLM is more effective than traditional FEM in nonlinear iteration. The results of FEM-TLM have been compared and analyzed under different calculation scales. It is found that the LU decomposition method is more suitable for FEM-TLM because there is no need to repeatedly assemble the global coefficient matrix in the iterative solution process and it is not affected by the disturbance of the right-hand vector.Originality/valueAn effective algorithm is provided for solving nonlinear problems in the electromagnetic field, which can save a lot of computing costs. The efficiency of LU decomposition and CG method in FEM-TLM nonlinear iteration is investigated, which also makes a preliminary exploration for the research of FEM-TLM parallel algorithms.

An experimental demonstration of the memristor test

A simple and unambiguous test has been recently suggested [J. Phys. D: Applied Physics, 52, 01LT01 (2018)] to check experimentally if a resistor with memory is indeed a memristor, namely a resistor whose resistance depends only on the charge that flows through it, or on the history of the voltage across it. However, although such a test would represent the litmus test for claims about memristors (in the ideal sense), it has yet to be applied widely to actual physical devices. In this paper, we experimentally apply it to a current-carrying wire interacting with a magnetic core, which was recently claimed to be a memristor (so-called `$\Phi$ memristor') [J. Appl. Phys. 125, 054504 (2019)]. The results of our experiment demonstrate unambiguously that this `$\Phi$ memristor' is not a memristor: it is simply an inductor with memory. This demonstration casts further doubts that ideal memristors do actually exist in nature or may be easily created in the lab.

MAGNETIC FIELD COMPUTATION OF A LOADED TRANSFORMER

A simple numerical method based on integral approach was described to compute the stray magnetic field in the surrounding region of a loaded distribution transformer. The model for magnetic field computation was made of transformer windings and low voltage conductors. Windings were modeled by rectangular and round blocks with uniform amper-turn distribution throughout the winding cross section. Low voltage conductors were modeled as series of straight current-carrying wire segments. The computed and measured results of magnetic induction are in good agreement.

Enhancement of charging and discharging of phase change material in annular thermal energy storage unit by applying magnetic field

One of the most applicable geometries for a thermal energy storage unit is an annulus filled by phase change material (PCM). In time-sensitive applications, the charging and discharging rates of PCM are critical. In the early stage of the period, the phase change rate is high, and it becomes so low by progressing the time, especially in the pure conduction zone at the later stage. Staggering the tube increases the charging or discharging rates and decreases another. The enhancement of both the charging and discharging rates is desirable. To achieve this in the present study, to improve the heat transfer and phase change rates, the application of the magnetic field of an electric current-carrying wire at the top or the bottom of the annulus in order to induce a convection heat transfer in the nanoparticles-enhanced PCM (NePCM) is presented. The solution is validated with experimental and numerical data. The predicted result indicates that employing the wire at the top of the annulus can reduce the solidification time by 25%. The application of the magnetic field is more efficient in the charging process where the wire is employed under the annulus, which intensifies the melting rate up to 40%. Accordingly, considering the appropriate locations of the wire, a conceptual design of thermal energy storage unit under the magnetic field efficient in both charging and discharging processes is developed.

Numerical study of magnetic field interaction with fully developed flow in a vertical duct

Ducts are conduits or passages used to supply, return, or exhaust air, needed for heating, ventilation, or air conditioning in multistory gigantic building structures. Rapid growth in population (especially in industrially concentrated regions) has led to the culture of constructing skyscrapers of tens of storeys, in which vertical ducts are the natural choice for removing polluted air. Due to the compactness of the building design, high voltage current-carrying wires are usually located very close to exhaust ducts carrying polluted air. Consequently, a natural motivation is to study how the magnetic field produced by such a wire affects the flow, driven by an external pressure gradient (for example, exhaust fan, vacuum pump, etc.) in a vertical duct. Therefore, the paper is devoted to understanding the interaction of the developed (thermally and hydrodynamically) flow in a vertical square duct with the magnetic field produced by a nearby placed current-carrying wire. The flow is assumed to be laminar and is driven by a constant external pressure gradient. For the thermal boundary condition, we assume a uniform heat flux across the unit axial length whereas a fixed temperature is also assumed over the peripheral surface of the duct. As a result of the mathematical modeling of the problem, we come across a system of coupled Poisson-like equations which are solved numerically by following a finite volume approach. We have noted that a sufficiently higher Rayleigh number may cause a reverse flow while reducing and flattening the thermal distribution in the middle of the duct. In addition the magnetic field further reduces the flow velocity, particularly near the duct wall where the current-carrying wire (causing the magnetic field) is positioned.

Linear stability of a ferrofluid centred around a current-carrying wire

Investigated first is the linear stability of a Newtonian ferrofluid centred on a rigid wire, surrounded by another ferrofluid with a different magnetic susceptibility. An electric current runs through the wire, generating an azimuthal magnetic field that produces a magnetic stress at the interface of the fluids. Three-dimensional disturbances to the system are considered, and the linearised Navier–Stokes equations are solved analytically in terms of an implicit expression for the growth rate of the disturbance. The growth rate is found numerically for arbitrary Reynolds number, and given explicitly in the inviscid and Stokes regimes. Investigated next is a ferrofluid whose magnetic susceptibility varies radially, centred on a rigid wire, subject to a non-uniform azimuthal field. It is proven that if the gradient of the susceptibility is positive anywhere in the fluid, then the system is linearly unstable. Moreover, it is proven that applying an axial field can stabilise disturbances for both continuous and discontinuous susceptibilities.