Study on the Effect of Magnetic Field on Temperature Domain During Electrolytic Processing

A physical model, mathematical model and geometric model of multi-physical field (electric field, flow field, temperature field, magnetic field) were established to explore the influence of magnetic field on the temperature domain in the gap during ECM. The change law of temperature domain of ECM gap under different magnetic field design methods was studied by using COMSOL MULTIPHYSICS. The scheme is as follows: the magnetic field line is perpendicular to the electric field and the flow field is parallel; the magnetic field line is parallel to the electric field and the flow field is vertical; the electric field of the magnetic field is vertical and the flow field is vertical. The change law of the influence of the magnetic field on the electrolyte temperature is studied by simulation. The changes of current density under three magnetic field design methods and different electrolyte flow were studied. The simulation results show that when the magnetic field is perpendicular to the electric field and the flow field, the temperature change is relatively gentle, and the flow field changes uniformly under the action of the magnetic field volume force, so that the change of current density is relatively stable; The current density of anodic dissolution increases with the increase of voltage, resulting in the increase of electrolyte temperature and heat, further reducing the gap and machining gap, and the temperature in the gap will be greatly increased. Under the action of magnetic field, the electrolyte flow rate increases and the electrolyte temperature decreases greatly.

Ultra-long and quite thin coronal loop without significant expansion

Context. Coronal loops are the basic building blocks of the solar corona. They are related to the mass supply and heating of solar plasmas in the corona. However, their fundamental magnetic structures are still not well understood. Most coronal loops do not expand significantly, but the diverging magnetic field would have an expansion factor of about 5−10 over one pressure scale height. Aims. We investigate a unique coronal loop with a roughly constant cross section. The loop is ultra long and quite thin. A coronal loop model with magnetic helicity is presented to explain the small expansion of the loop width. Methods. This coronal loop was predominantly detectable in the 171 Å channel of the Atmospheric Imaging Assembly (AIA). Then, the local magnetic field line was extrapolated within a model of the potential field source-surface. Finally, the differential emission measure analysis made from six AIA bandpasses was applied to obtain the thermal properties of this loop. Results. This coronal loop has a projected length of roughly 130 Mm, a width of about 1.5 ± 0.5 Mm, and a lifetime of about 90 min. It follows an open magnetic field line. The cross section expanded very little (i.e., 1.5−2.0) along the loop length during its whole lifetime. This loop has a nearly constant temperature at about 0.7 ± 0.2 MK, but its density exhibits the typical structure of a stratified atmosphere. Conclusions. We use the theory of a thin twisted flux tube to construct a model for this nonexpanding loop and find that with sufficient twist, a coronal loop can indeed attain equilibrium. However, we cannot rule out other possibilities such as footpoint heating by small-scale reconnection or an elevated scale height by a steady flow along the loop.

Modular on-Road Self-Guided Automatic Vehicle and Concept of Self-Power Transmission

A self-guided automated robot is basically a robot designed to follow a line or path which is already pre-determined by the user. The main focus of this report is to design a selfguided automated path following robot which is more reliable by eliminating the demerits of the traditionally used robots by the idea of making it a magnetic field line following robot. This paper presents the principle of a magnetic field line following robot and also explains its design and working. Here, the design of a self-guided automated magnetic field line following robot using LC tank circuits and resonant coupling for navigation purposes is explained. Also this paper gives the idea of a path that can be made invisible and can be buried under the ground and also focuses on the various electrical circuitries involved in this self-guided automated magnetic field line following the robot. This paper discusses all the components that are used in this self-guided automated vehicle. The applications and the advantages of this self-guided automated magnetic field line following robot over the traditional path following robots are discussed along with the future upgradations that can be done to refine it further.

Possible Generation Mechanism for Alfvenic Velocity Spikes and Magnetic Field Switchbacks as Observed by PSP

<div>According to Parker's theory in the 1950s, the magnetic lines of force extending from the sun to the interplanetary appear to be Archimedean spirals. From 1960 to 1970, it was found that the interplanetary magnetic field not only follows the Archimedes spiral structure, but also has the characteristics of Alfvenic turbulence. How do these Alfvenic turbulence occur? What will be the characteristics when getting close to the Sun? Parker Solar Probe at 0.17au has found that there are often intermittent Alfvenic pulses (or called Alfvenic velocity spikes) in the solar wind. These pulses are high enough that the disturbed magnetic lines may even turn back. What's more interesting is that there is always a compressibility disturbance along with the Alfven pulse: the temperature and density inside and outside the Alfven pulse are different, the internal temperature is often higher than the external temperature, some of the internal density is higher than the external and some is lower than the external. The Alfven pulse often shows asymmetry on both sides: the magnetic field and velocity on one side are "clean" jumps, while on the other side are multiple small-scale disturbances of variables in the transition boundary layer. In view of this new phenomenon of magnetic field line switch back with compressed Alfven pulse, how it is generated is raising a hot debate. It is thought that the exchange magnetic reconnection of the solar atmosphere may be the underlying physical mechanism. But in the traditional exchange magnetic reconnection image, after reconnection, the zigzag magnetic field line can easily become smooth, which can not maintain the distortion of the magnetic field line, and may not be able to explain the observed Alfven pulses. In this work, we propose a new model called "Excitation of Alfven Pulses by Continuous Intermittent Interchange Reconnection with Guide Field Discontinuity" (EAP-CIIR-GFD). By analyzing and comparing the simulation results and observation results, we find that the model can explain the following observation features: (1) Alfven disturbance is pulse type and asymmetric; (2) Alfven pulse is compressible with the enhancement of internal temperature and the increase or decrease of the internal density; (3) Alfven pulse can cause serious distortion of the magnetic field line. Improvements to the model will also be discussed in the report.</div>