Stable Arc Research Articles

Stable isotopy connectivity of gradient-like diffeomorphisms of 2-torus

One of the most important problems in the theory of dynamical systems (mentioned in the Palis-Pugh list) is the construction of a stable arc between structural stable diffeomorphisms in the space of diffeomorphisms. The paper considers the gradient-like diffeomorphisms of 2-torus that induce an isomorphism of fundamental groups determined by a matrix (−100−1). We prove that all such diffeomorphisms are stable isotopy connected.

Efficient heuristics to compute minimal and stable feedback arc sets

Given a directed graph G=(V,A)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$G=(V,A)$$\\end{document}, we tackle the Minimum Feedback Arc Set (MFAS) Problem by designing an efficient algorithm to search for minimal and stable Feedback Arc Sets, i.e. such that none of the arcs can be reintroduced in the graph without disrupting acyclicity and such that for each vertex the number of eliminated outgoing (resp. incoming) arcs is not bigger than the number of remaining incoming (resp. outgoing) arcs. Our algorithm has a good polynomial upper bound and can therefore be applied even on large graphs. We also introduce an algorithm to generate strongly connected graphs with a known upper bound on their feedback arc set, and on such graphs we test our algorithm.

Optimization of TIG welding parameters for tensile load testing on dissimilar material joints of galvanized steel (SGCC) and low carbon steel (SPCC-SD)

Tungsten Inert Gas (TIG) welding uses a tungsten electrode and argon or helium gas for shielding. It offers excellent shielding, stable arc, adjustable heat input, minimal spattering, and attractive welds. Widely used in various industries, especially for thin materials like galvanized sheets, TIG welding can be challenging for dissimilar materials like galvanized steel and low-carbon steel due to their different melting points. Studying optimal welding parameters is crucial for success. This research focuses on TIG welding of SPCC-SD (JIS 3141) and SGCC (JIS 3302) materials with thicknesses of 0.6 mm and 0.8 mm. The electric current was varied at 45, 50, and 55 A, whereas the gas flow rate was varied at 12, 15, and 18 LPM. The weld bead diameter was varied as 5, 8, and 10 mm. Subsequently, the welded samples were subjected to tensile testing using a SHIMADZU AGS-X 10Kn STD E200V tensile testing machine. The data from the tensile tests were analysed using S/N ratio analysis and Analysis of Variance (ANOVA) with the assistance of the Minitab software. The results of the S/N ratio analysis indicated that the most optimal parameters were an electric current of 55 A, flow rate of 15 LPM, and weld bead diameter of 10 mm. Conversely, the ANOVA revealed that the weld bead diameter significantly influenced the tensile load in TIG welding of SPCC-SD (JIS 3141) with SGCC (JIS 3302) materials, accounting for up to 44.42% of the variation. Following the weld bead diameter, the flow rate and welding current contributed to 21.93% and 16.41%, respectively.

Универсальная централизованная защита от однофазных замыканий на землю в кабельных сетях напряжением 6–10 кВ

Selective protection against single phase earth faults in distribution 6–10 kV cable networks can be performed both with the use of individual (per connection) and centralized devices covering all connections of the protected object. The advantages of centralized devices are reduction of specific (per connection) costs of protection, simplification of its operation and design. Well-known technical solutions in terms of centralized protection devices against this type of damage do not always provide versatility (the possibility to use neutral cables of 6–10 kV in various grounding modes) and high technical perfection (selectivity and stability of operation). Thus, it is relevant to develop a universal centralized protection against single-phase earth faults, ensuring high technical perfection for all types of earth faults in 6–10 kV cable networks with different neutral grounding modes. The authors have used a comprehensive simulation model "cable network – protection device" to study the selectivity and stability of the developed principles of implementation and algorithms for centralized protection against earth faults. The model is designed in SimPowerSystems and Simulink software. The configuration and parameters of the cable network model have been selected considering the key features of 6–10 kV distribution cable networks of industrial and urban power supply systems. A universal centralized protection against all types of earth faults in 6–10 kV cable networks with various neutral grounding modes has been developed. The results of functional tests on the simulation model have confirmed the effectiveness of the developed algorithms of the developed centralized protection for all types of earth faults both in uncompensated and compensated cable networks of 6–10 kV. The proposed technical solution implements a multifunctional multiparametric centralized protection against earth faults. It has such properties as versatility, selectivity, and high stability of operation for all types of earth faults, recognition of types of single-phase earth faults, continuity of action in stable and most dangerous arc intermittent earth faults.

Numerical simulation of arc stabilizing cycle in vacuum arc remelting of titanium alloy

Through utilizing numerical simulation methods, the flow state of the molten pool during the vacuum self-consumption melting process of titanium alloy was analyzed. The influence of the stable arc cycle on the shape of the molten pool, dendrite arm spacing, surface quality, and shrinkage cavity was examined. The results showed that without an external magnetic field, the molten pool for smelting a Φ720 mm specification titanium alloy ingot is dominated by self-inductance magnetic force, leading to a downward flow in the central part of the melt. A mere 0.5 G stray magnetic field can result in Ekman pumping, causing an upward secondary flow in the core to counteract it. At an externally added magnetic field strength of 50 G, choosing a 10 s-20 s cycle can achieve a relatively stable double loop flow pattern. The shape of its molten pool, dendrite arm spacing, and contact ratio all reach optimal performance, thus verifying the possibility and feasibility of the double loop flow, and the macroscopic segregation of the simulated ingots essentially matches the experimental results, aiming to provide references for selecting parameters in actual production.

Experimental and model analysis of the thermoelectric characteristics of serial arc in prismatic lithium‐ion batteries

AbstractAiming at the electrical safety problems of lithium‐ion battery system due to series arc fault, a finite element simulation model of square battery under series arc fault is established based on the magnetohydro‐dynamic equations. The arc voltages at different electrode spacings are analysed, and the electric field distribution, magnetic field distribution, arc temperature and flow velocity around the arc are investigated to determine the maximum values and locations of the electric field strength, magnetic density, arc temperature and flow velocity at the time of the arc fault. Then, on the basis of the series arc experimental platform, determine the value of the arc starting voltage and the critical power supply voltage that produces a stable arc, analyse the evolution of the arc burning time with different loop currents, the evolution of the arc of the separation gap, and then summarise the effect of the disaster on the battery. Finally, the errors of simulation and experimental arc voltage and battery surface temperature are analysed to verify the accuracy of the model.

Effect of power supply parameters on discharge characteristics and sterilization efficiency of magnetically driven rotating gliding arc

Plasma sterilization is a new generation of high-tech sterilization method that is fast, safe, and pollution free. It is widely used in medical, food, and environmental protection fields. Home air sterilization is an emerging field of plasma application, which puts higher requirements on the miniaturization, operational stability, and operating cost of plasma device. In this study, a novel magnetically driven rotating gliding arc (MDRGA) discharge device was used to sterilize Lactobacillus fermentation. Compared with the traditional gas-driven gliding arc, this device has a simple structure and a more stable gliding arc. Simulation using COMSOL Multiphysics showed that adding permanent magnets can form a stable magnetic field, which is conducive to the formation of gliding arcs. Experiments on the discharge performance, ozone concentration, and sterilization effect were conducted using different power supply parameters. The results revealed that the MDRGA process can be divided into three stages: starting, gliding, and extinguishing. Appropriate voltage was the key factor for stable arc gliding, and both high and low voltages were not conducive to stable arc gliding and ozone production. In this experimental setup, the sterilization effect was the best at 6.6 kV. A high modulation duty ratio was beneficial for achieving stable arc gliding. However, when the duty ratio exceeded a certain value, the improvement in the sterilization effect was slow. Therefore, considering the sterilization effect and energy factors comprehensively, we chose 80% as the optimal modulation duty ratio for this experimental device.

Influence of shielding gas flow on the TIG welding process using stainless steel 304 material

A common issue encountered with main heat exchanger equipment is improper operation, which can lead to the development of cracks in the stainless-steel pipes. The welding process alters the metal microstructure in the heat-affected zone, thereby affecting the mechanical properties of the welded joint. To mitigate this issue, TIG welding with argon shielding gas is employed. This method helps prevent oxidation and ensures the formation of a stable welding arc in 304 stainless steel, which is renowned for its excellent mechanical properties and corrosion resistance. The objective of this study is to evaluate the impact of variations in shielding gas flow on the mechanical properties of 304 stainless steel plates during the TIG welding process. The aim is to determine the optimal settings for producing robust and long-lasting welded joints. To assess the hardness of the welded joints, we employed a Brinell-type Hardness Tester FB-3000LC machine. A Brinell steel ball indenter measuring 5 mm on the HBW scale and applying a load of 125 Kgf was utilized. At a protective gas flow rate of 8 L/min, the average tensile stress was 44.72 N/mm², strain was 0.177, modulus of elasticity was 2518 MPa, and hardness was 99.712 HBW. Increasing the gas flow rate to 13 L/min resulted in an average tensile stress of 47.50 N/mm², strain of 0.189, elastic modulus of 2525 MPa, and hardness of 105.522 HBW. Further increasing the gas flow rate to 18 L/min led to an average tensile stress of 49.69 N/mm², strain of 0.192, modulus of elasticity of 2597 MPa, and hardness of 106.704 HBW. Based on the research findings, it was observed that the weld area exhibited an increase in hardness values due to the heat generated during the welding process. The use of protective gas flow during welding is deemed effective in producing well-formed welded joints, as it prevents fractures from occurring within the weld area during the tensile test process. The choice of protective gas is determined by the dimensions of the material plate.

The development of B/Cr co-doped DLC coating by FCVA deposition system and its tribological properties at 300 °C

The diamond-like carbon (DLC) coating prepared using filtered cathodic arc deposition (FCVA) lost its promising wear resistance under high temperatures. Element-doped DLC coatings have been investigated to suppress carbon oxidation reaction and subsequently enhance the wear resistance in high-temperature environments. Previous research clarified the excellent tribological properties of boron-doped DLC (B-DLC) but identified challenge such as arc discharge extinguishment and coating declamation (under high-temperature friction test). In this study, the introduction of Argon gas (10 sccm) during the deposition process stabilized stable arc discharge, resulting in high hardness and deposition rate. Moreover, a chromium interlayer and varying concentration of Cr dopant (0.5 %, 1.0 %, 3.0 % at.) were added to B-DLC to develop a stable, co-doped DLC with low friction and high wear resistance. Raman spectroscopy and nano-indentation revealed an increase in the disordered carbon structure and reduction in hardness and Young's Modulus with Cr doping. Macroscopic ball-on-disk friction test, showed 1 % Cr-doped B-DLC (a-C:B:Cr1) coating exhibited super low friction (avg. coefficient 0.02) and a low specific wear rate (<5.0 × 10−6 mm3/Nm). Raman spectroscopy indicated that the transferred graphite-like tribo-film onto the surface of Si3N4 counterparts contributed to stable low friction. Additionally, XPS analysis on the DLC coatings' wear track suggested the rich BB bond might contribute to its high wear resistance. This successful improvement on element-doped DLC prepared by FCVA provided valuable insights for further exploration of DLC coating applied to various working situations.

Stable DC vacuum arc plasma generation from a 100 mm TiB2 cathode

Titanium diboride exhibits outstanding properties for hard and wear resistant coatings. However, efficient physical vapor deposition (PVD) processing through DC vacuum arc, with a deposition rate unreachable for any other PVD technique, is comparatively unexplored for TiB2 thin films due to challenges associated with the film synthesis process. In this work, we used an industrial scale arc plasma source having a plane cathode of 100 mm in diameter and a permanent magnet on its back side. We present analysis of the cathode surface, plasma generation/composition, as well as analysis of collected macroparticles. The cathode weight loss and the amount of generated macroparticles were measured as a function of process parameters (arc current and pressure, in both Ar and N2 gas). Plasma analysis shows average ion energies around 120 and 25 eV for Ti and B, respectively, and plasma ion composition of approximately 50 % Ti and 50 % B. The cathode weight loss was around 0.3–0.5 g/min, of which at least 25 % is estimated to be macroparticles. Notably, the intensity of the macroparticle generation was reduced with an increase in N2 pressure. Altogether, the results show a stable and reproducible plasma generation process and a high potential for the use of the cathodic arc as an efficient and useful method for deposition of metal borides.

Arc erosion behaviors of the densified Ag-SnO2 contact materials containing sub-micron and nano In2O3 additives

The effects of In2O3 additive size on the physical properties and arc erosion behaviors of the densified Ag-SnO2 materials were investigated. Arc resistance mechanism was analyzed based on the microscopic morphology characterization. Results revealed that the physical properties of the Ag-SnO2(In2O3) materials were significantly improved after densification. Relative density and electrical conductivity of the materials reached above 99.5% and 71%IACS, respectively. The densified Ag-SnO2 material containing sub-micron In2O3 showed the low and stable break arc energy. The mass loss of the cathode was dramatically decreased by 65.4%. Importantly, the generation of pores and micro-cracks on the surface of electrodes were significantly restrained and the contact resistance became more stable. By comparison, the nano In2O3 additive less than 100 nm effectively suppressed not only the splash of molten Ag on the surface of cathode but also the aggregation of SnO2 particles on anode. The arc erosion products were obviously decreased, resulting in an enhancement of arc-erosion resistance of Ag-SnO2(nano In2O3) materials. Compared with that without additive, the mass loss of the Ag-SnO2 material which contains nano In2O3 obviously decreased from 2.3 to 1.4 mg. The optimal mass fraction of nano In2O3 in the Ag-SnO2 contact materials was 1 wt%.

Experimental study on the full cycle evolution of high-intensity atmospheric dc arc discharge from breakdown to extinguishment.

In this study, the spatiotemporal evolution of full cycle of high-intensity dc argon arc discharge at atmospheric pressure is investigated by using a transferred arc device, which is easy to be directly observed in the experiment. Combining the voltage and current waveforms with high-speed images, the full cycle evolution process of high-intensity atmospheric dc arc can be divided into five different stages: breakdown pulse stage, cathode heating stage, current climbing stage, stable arc discharge stage, and finally arc extinguishing stage. The characteristics of each different stage are analyzed in detail through the electrical properties, high-speed pictures, and spectroscopic measurements. The results show that the strong luminescence region develops from the vicinity of cathode and anode to the middle in the breakdown pulse stage, which is explained from the spatiotemporal evolution of distributions of excited argon atom and ions. The development velocity of emission intensity of argon ions is mainly determined by the dominant stepwise ionization process. Then the cathode heating stage appears with many bright and nonuniformly distributed light spots on the cathode surface, and the electron emission mechanism of cathode gradually changes to the thermionic emission as the surface temperature rises. With the increase of arc current, the discharge channel significantly expands, then becomes stable due to the increment of the Lorentz force. The characteristics of arc extinguishing stage are clarified in terms of the decay of charged particles density.

Scenario of stable transition from diffeomorphism of torus isotopic to identity one to skew product of rough transformations of circle

In this paper, we consider gradient-like diffeomorphisms of a two-dimensional torus isotopic to the identical one. The isotopicity of diffeomorphisms $f_0$, $f_1$ on an $n$-manifold $M^n$ means the existence of some arc $\{f_t:M^n\to M^n,t\in[0,1]\}$ connecting them in the space of diffeomorphisms. If isotopic diffeomorphisms are structurally stable (qualitatively not changing their properties with small perturbations), then it is natural to expect the existence of a stable arc (qualitatively not changing its properties under small perturbations) connecting them. In this case, one says that the isotopic diffeomorphisms $f_0$, $f_1$ are stably isotopic or belong to the same class of stable isotopic connectivity. The simplest structurally stable diffeomorphisms on surfaces are gradient-like transformations having a finite hyperbolic non-wandering set, stable and unstable manifolds of various saddle points of which do not intersect. However, even on a two-dimensional sphere, where all orientation-preserving diffeomorphisms are isotopic, gradient-like diffeomorphisms are generally not stably isotopic. The countable number of pairwise different classes of stable isotopic connectivity is constructed on the base of a rough transformation of the circle $\phi_{\frac{k}{m}}$ with exactly two periodic orbits of the period $m$ and the rotation number $\frac{k}{m}$, which can be continued to a diffeomorphism $F_{\frac k m}:\mathbb S^2\to\mathbb S^2$ with two fixed sources at the North and South poles. On the torus $\mathbb T^2$, the model representative in the considered class is the skew products of rough transformations of a circle. We show that any isotopic gradient-like diffeomorphism of a torus is connected by a stable arc with some model transformation.

Unveiling arc deflection instability in narrow gap laser-arc hybrid welding of thick Ti-6Al-4V plate

Unveiling the mechanism behind arc deflection under narrow gap laser arc hybrid welding (NGLAHW) is of paramount significance in mitigating laser-arc coupling failure and welding porosity for thick Ti-6Al-4V plate structure. This paper utilizes high-speed camera technology, data statistics and model prediction to comprehensively study the influence of constrained groove space and droplet transfer mode on arc deflection. The results demonstrate that narrowing groove gap exerts a substantial compressive effect on welding arc behavior, particularly rendering it more susceptible to arc deflection when the groove gap is smaller than the arc length. The small droplet transfer mode is characterized by stable arc behavior, whereas the large droplet transfer mode tends to be susceptible to arc instability due to the droplet deviation induced by turbulent metal vapor. Particularly noteworthy is the emergence of substantial arc deflection when the droplet deviation exceeds the critical threshold of 0.51 mm, which diminishes the driving force for droplet transfer and subsequently leading to potential short-circuiting explosions and unstable welding process. Moreover, the lateral force induced by arc deflection drives a deviation in arc heat source with accelerated solidification of molten pool, consequently resulting in an elevation in welding porosity. This paper has provided a comprehensive insight into the mechanism driving arc deflection in NGLAHW, which holds paramount importance in enabling effective strategies to regulate the arc behavior.

Effects of deposition height stability of CuCrZr alloy based on arc voltage sensing: Influence of materials and energy saving on wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) is a promising process technology to produce large-size metal parts. Nevertheless, it is a challenging task to deposit Cu alloys by WAAM due to their high thermal conductivity. Poor quality of geometry and height stability result in significant material waste and energy consumption. In this paper, a control system based on arc voltage sensing was developed for monitoring and controlling the deposition progress of CuCrZr alloy. An empirical mode decomposition (EMD) filtering method was used to filter out the random noise in the original arc voltage signals. A novel dual control method combining height lifting control and iterative learning control was proposed, where the lifting height and wire feed speed were used as manipulated variables and the arc voltage was the controlled variable. The effectiveness of control system was tested through the deposition of single-channel multi-layer thin walls. Compared with the conventional method, the energy input is reduced by 28.7%, and the effective material forming utilization is increased by 50.0%. More stable arc voltage and better forming quality indicate that arc voltage sensing and dual control method are effective in improving height stability and enhancing material and energy utilization.

Numerical simulation of coupling behavior in coaxial hybrid arc welding apparatus

Double-layer coaxial hybrid arcing technology has been developed based on an inner constraint arc and an outer ring arc; the heat and pressure properties of the arc source are supposed to be decoupled and leading to improved controllability of the weld pool thermal-force state. But, the coupling state between the two arcs is not uncovered, and the process window for stable hybrid arc is narrow. In this study, a numerical model of the coaxial hybrid arc system is established, the influence of the water-cooled nozzle on the arc is considered, and the model's accuracy is verified by the measured arc pressure. The physical fields, such as temperature, velocity, and current density distribution, of the hybrid arc are calculated, and the influence of the inner constraint arc current or outer ring arc current on arc pressure and the coupling state in the hybrid arc are uncovered. It was found that (1) at the center of the stable hybrid arc, the current density, magnetic flux intensity, Lorentz force, and arc pressure with a rise in constraint arc current are higher than with a rise in outer arc current; (2) given the total current, adjust the proportion of the inner or outer arc currents, the total heat input basically remains unchanged; and (3) the cause of the arc collapse phenomenon, which is challenging to explain experimentally: the non-ionized gas layer in the orifice throat is broken through.

Research on High Voltage Protection of Arc Thruster Power Control Unit

The arc propulsion system needs a high-voltage (3800 V) pulse to break down the working medium in the thruster and form a stable arc. The arc thruster power control unit (ATPU) is prone to producing high voltage discharge when the high voltage pulse is output. According to the high voltage breakdown mechanism, this paper puts forward control measures to prevent the high voltage breakdown.

Experimental identification of the electrical discharge on a surface gap spark plug

The main objective of the research is to assess the influence of the spark plug electrodes geometry on the structure of the electric arc. This issue is increasingly important in modern gas-fueled engines with lean and stratified air-gas mixtures. To explain the influence of electrode geometry on selected spark discharge indicators, optical tests were conducted, and the parameters of the test history, together with the movies of the discharging process, were recorded and analyzed. The tests were carried out comparatively for two types of spark plugs on the test stand: conventional spark plug and spark plug with a flat ground electrode. It has been found that using flat plug electrodes allows a larger spark area covered by the electric arc without losing the intensity of radiation. More, using an unconventional spark plug results in a shorter discharge time relative to the conventional spark plug, while the geometry of the conventional spark plug allows for maintaining a stable electric arc with a minimum tendency for creeping.

The effect of weld groove variations on the toughness of welding joints of AISI 1050 material

SMAW (Shielded Metal Arc Welding) welding is a metal joining process that uses heat energy to melt the workpiece and electrode (fill material). The flux material used for type E7016, a low hydrogen electrode wire typically used for welding heavy-duty plates and structures. Its use is for welding medium carbon steel, bridges, ships and machinery. The result of welding electrode E7016 is very smooth, deep penetration, crack resistant, ductile, good weld appearance and stable arc, the material used in the SMAW welding process is AISI 1050 steel. While AISI 1050 steel is steel that has a carbon content of 0.50 % so that it is classified as medium carbon steel. This steel is widely used in the market because it has many advantages, one of which is as an automotive component. This steel has the characteristics of good machinability, good wear resistance and medium mechanical properties. This study aims to determine the shock strength (impact) and the difference in the time of making weld grooves on SMAW welding results on AISI 1050 steel with variations of Double Bevel and Double V Groove grooves. In testing in the Weld Metal area with a current used of 110 Ampere. From the tests that have been carried out, it is known that the value of the highest impact strength is in the Double Bevel groove which has a value of 1.91 Joule/mm2, for the manufacture of welded grooves where the Double Bevel time is shorter than Double V Groove, so the time produced by Double Bevel which is 3.44 minutes/second.

Physical characteristics of triple-wire gas indirect arc plasma

The triple-wire gas indirect arc welding (TW-GIA) has advantages of high deposition rate and low heat input. However, due to the lack of accurate understanding of the physical characteristics of arc plasma, the further development of this technology is restricted. In this paper, numerical simulation is used to quantitatively analyze the arc physical characteristics of TW-GIA. The results show that the TW-GIA consists of two separate arcs during the ignition stage, and then gradually couples into a single inverted cone arc. The arc temperature is symmetrical along the main wire. The current density of the stable arc is concentrated at the end of the three wires, and the maximum current density of the main wire end is 2.28–2.92 times that of the side wire. The magnetic field intensity at the symmetrical position along the main wire is in the opposite direction, and the values are basically the same. In the X-axis direction, the energy flow density presents an “M" type characteristic. In the Y-axis direction, as the distance from the main wire increases, the energy flow density first decreases sharply, then slowly increases, and then decreases. The measured arc morphology and electron temperature agree well with the calculated results.