Arc Conditions Research Articles

Double functionalization of a fullerene in drastic arc-discharge conditions: synthesis and formation mechanism of C2v(2)-C78Cl6(C5Cl6)

Arc-discharge of graphite is the most prevalent technique for synthesis of novel fullerenes, but the extreme conditions of the carbon arc prevent any currently available instrument from detecting the reaction species inside. To detour the difficulties for probing the derivatization mechanism in the drastic arc-discharge conditions, C78Cl6(C5Cl6) with prototypical C2v(2)-C78 cage has been isolated and characterized in the products of the chlorine-involving carbon arc. The structure of C2v(2)-C78Cl6(C5Cl6), featuring with fullerene C2v(2)-C78 doubly functionalized by chlorine atoms and perchlorinated cyclopentadiene, has been identified by X-ray crystallography. Confirmed by standard Density Functional Theory (DFT) calculations and Car-Parrinello simulations as well as mass spectrometry, the fullerene core has been revealed to form firstly followed then by reaction with chlorine atoms and afterwards with perchlorinated cyclopentadiene, with implication about stepwise reaction temperatures and sequences for the formation of fullerenes and their derivatives in the otherwise inaccessible extreme conditions of the carbon arc.

Research on Time Domain Characteristics and Mathematical Model of Electromagnetic Radiation Noise Produced by Single Arc

Current-carrying sliding friction pair is the key part of many systems such as high-speed railway’s pantograph-catenary system, electromagnetic gun’s launch system, and space satellite’s solar panel system. Arc discharge phenomenon will occur due to sliding electrical contact fault. It will radiate high-intensity electromagnetic noise. The electromagnetic radiation noise (EMRN) will disturb communication system, even cause failure of the whole system. EMRN experiments under single arc conditions were carried out with the self-developed experimental system in anechoic chamber environment. The time domain characteristics of EMRN were analyzed under different measure distance and contact current conditions. The time domain waveform of EMRN is symmetrical and convergent. Its continuous time is shorter than 0.8 $\mu \text{s}$ . A mathematical model of the time domain waveform was established by using the least-square method. The performance of the model was evaluated by using determination coefficient, residual standard deviation, and correlation coefficient. The time domain waveform obtained from the model is almost the same as the waveform measured from experiments.

Electric Arc Furnace Modeling with Artificial Neural Networks and Arc Length with Variable Voltage Gradient

Electric arc furnaces (EAFs) contribute to almost one third of the global steel production. Arc furnaces use a large amount of electrical energy to process scrap or reduced iron and are relevant to study because small improvements in their efficiency account for significant energy savings. Optimal controllers need to be designed and proposed to enhance both process performance and energy consumption. Due to the random and chaotic nature of the electric arcs, neural networks and other soft computing techniques have been used for modeling EAFs. This study proposes a methodology for modeling EAFs that considers the time varying arc length as a relevant input parameter to the arc furnace model. Based on actual voltages and current measurements taken from an arc furnace, it was possible to estimate an arc length suitable for modeling the arc furnace using neural networks. The obtained results show that the model reproduces not only the stable arc conditions but also the unstable arc conditions, which are difficult to identify in a real heat process. The presented model can be applied for the development and testing of control systems to improve furnace energy efficiency and productivity.

Paleomagnetism and accretionary tectonics of northern Sikhote Alin

The results of the paleomagnetic investigation of the sediments pertaining to the Silasinskaya Formation of the Kiselevka–Manoma terrane within the Sikhote Alin orogenic belt are presented. The ancient prefolding magnetization component is revealed: Decs = 271.7°, Incs = 52.2°, Ks = 13.5, and a 95s = 5.1° (positive fold and reversal tests); and the coordinates of the corresponding paleomagnetic pole for ~103 ± 10 Ma are calculated: Plat = 26.3°, Plong = 70.5°, dp = 4.8°, and dm = 7.0°. As a result of this study, the geodynamical settings and paleolatitudes of the formation of three objects in the northern part of Sikhote Alin orogen are established: (a) the Kiselevskaya Formation of the Kiselevka–Manoma terrane was formed 133 Ma ago at 19° N under the seamount condition on the Izanagi Plate; (b) the Silasinskaya Formation of the Kiselevka–Manoma terrane was formed 103 Ma ago at 35° N under the oceanic island arc conditions; and (c) the Utitskaya Formation of the Zhuravlevsk–Amur terrane was formed 95 Ma ago at 54° N in the active continental margin conditions. It is found that the transform continental margin of Eurasia developed in the time interval from 105 to 65 Ma ago in the regime of a left-lateral submeridional shear from 30° to 60° N. The complete attachment of the studied rocks of the Kiselevka–Manoma terrane to the Eurasia’s margin (to the Zhuravlevsk–Amur terrane) occurred at the boundary of 60–70 Ma. Simultaneously, the sense of the displacement in the submeridional shears changed from left-lateral to right-lateral with the formation of pullapart type basins (Lake Udyl’).

Arc Fault Detection Method Based on CZT Low-Frequency Harmonic Current Analysis

This paper presents a method for the detection of series arc faults in electrical circuits, which has been developed starting from an experimental characterization of the arc fault phenomenon and an arcing current study in several test conditions. Starting from this, the authors have found that is it possible to suitably detect arc faults by means of a high-resolution low-frequency harmonic analysis of current signal, based on chirp zeta transform, and a proper set of indicators. The proposed method effectiveness is shown by means of experimental tests, which were carried in both arcing and nonarcing conditions and in the presence of different loads, chosen according to the UL 1699 standard requirements.

Copper-MAX-phase composite coatings obtained by electro-co-deposition: A promising material for electrical contacts

A new and promising composite coating system comprising copper and MAX phase particles (commercial powder consisting of Ti2AlC and Ti3AlC2) was prepared electrochemically using direct current electrodeposition. The MAX phase particles, in micro-scale sizes, were successfully incorporated (up to 3wt%) and well distributed in the copper coating. The change in the coating properties such as hardness, electrical contact resistance as well as crystallographic structure was investigated in layers having thickness values of about 50μm. Furthermore, the behavior of the composite layers under electrical arcing conditions was studied. Beside an increase of the hardness and a slight change in the structure due to particle incorporation, it could be shown that the electrical contact resistance of the composite coatings is similar to the one of pure copper films deposited at the same conditions. An improved behavior under electrical arcing was found for the composite coatings. After the arcing experiments no significant changes of the morphology of the composite coatings were found, whereas, the pure copper layers showed melting and recrystallization. The composite layers are, therefore, a suitable alternative for electrical applications such as electrical switching devices.

1997–2002 Solar Array String Failures Revisited

In 1997, two commercial geostationary satellites experienced a new phenomenon: sustained solar array arcing. Although arcing on solar arrays in space had been expected from ground tests and space flight experiments, it was heretofore unknown that arcs into the space plasma could turn into arcs between adjacent solar array strings at high interstring voltages. Experiments validated the concept, and design changes were made to succeeding satellites that have prevented similar occurrences. Here, the dates and times of 32 sustained arcing string failures from 1997 to 2002 are reported, and NASCAP-2k charging simulations are used to try to determine thresholds necessary for the arcs to occur. Surprisingly, in some cases, conditions for sustained arcs last for a longer time when the environment is relatively benign. A plausible scenario for primary arcs in sustained arcing conditions is presented that is based on charging time histories from NASCAP-2K simulations. The charging scenario involves solar array voltage turn-on after eclipse or upon unshunting the array, and it hypothesizes lower than usual arc voltage thresholds immediately after differential string voltages are activated. Laboratory testing under both geosynchronous-Earth-orbit and low-Earth-orbit conditions is cited to show plausibility of this argument. Improved design and testing rules for spacecraft to avoid sustained arcing with a minimum of overdesign are presented.

Geochemical features and sources of clastic material in Paleozoic terrigenous deposits of the northeastern flank of the South Mongolia–Khingan orogenic belt

The results of geological and geochemical studies of terrigenous rocks of the main stratigraphic subdivisions in the northeastern flank of the South Mongolia–Khingan orogenic belt and also the results of U-Pb (LА-ICP-MS) geochronological studies of detrital zircons from these deposits are presented. It is demonstrated that the studied rocks differ significantly in the nature of distribution of detrital zircon ages and, consequently, they cannot be members of a single sedimentary sequence. The data obtained confirm the standpoint according to which the northeastern flank of the South Mongolia–Khingan orogenic belt represents a “joint” zone separating the Argun and the Bureya-Jiamusi Superterranes. This joint zone was formed as the result of closure of the oceanic basin separating the specified continental massifs in the Paleozoic era. The geochemical features of the studied rocks indicate their formation in the conditions of the island arc or the active continental margin. Lack of zircon generations younger than Ordovician age in the studied samples allows assuming that the sedimentary sequences identified within the northeastern flank of the studied belt as the Necla, Dagmara, siltstone-sandstone, and Gramatukha sequences that formed from the end of the Vendian (?) to the Devonian correspond to the youngest stages of belt formation. These sediments in the current structural plan evidently represent fragments of accretion complexes cropping out in fragments among the Cenozoic sequences of the Amur-Zeya Depression.

On strict Whitney arcs and $t$-quasi self-similar arcs

A connected compact subset $E$ of $\mathbb{R}^{N}$ is said to be a strict Whitney set if there exists a real-valued $C^{1}$ function $f$ on $\mathbb{R}^{N}$ with $\nabla f|_{E}\equiv 0$ such that $f$ is constant on no non-empty relatively open subsets of $E$. We prove that each self-similar arc of Hausdorff dimension $s>1$ in $\mathbb{R}^{N}$ is a strict Whitney set with criticality $s$. We also study a special kind of self-similar arcs, which we call “regular” self-similar arcs. We obtain necessary and sufficient conditions for a regular self-similar arc $\Lambda $ to be a $t$-quasi-arc, and for the Hausdorff measure function on $\Lambda $ to be a strict Whitney function. We prove that if a regular self-similar arc has “minimal corner angle” $\theta_{\min }>0$, then it is a 1-quasi-arc and hence its Hausdorff measure function is a strict Whitney function. We provide an example of a one-parameter family of regular self-similar arcs with various features. For some values of the parameter $\tau $, the Hausdorff measure function of the self-similar arc is a strict Whitney function on the arc, and hence the self-similar arc is an $s$-quasi-arc, where $s$ is the Hausdorff dimension of the arc. For each $t_{0}\ge 1$, there is a value of $\tau $ such that the corresponding self-similar arc is a $t$-quasi-arc for each $t>t_{0}$, but it is not a $t_{0}$-quasi-arc. For each $t_{0}>1$, there is a value of $\tau $ such that the corresponding self-similar arc is a $t_{0}$-quasi-arc, but it is a $t$-quasi-arc for no $t\in [1,t_{0})$.

Aligning organizational priorities with ARC to improve youth mental health service outcomes.

The Availability, Responsiveness, and Continuity (ARC) organizational intervention is designed to improve community-based youth mental health services by aligning organizational priorities with 5 principles of effective service organizations (i.e., mission driven, results oriented, improvement directed, relationship centered, participation based). This study assessed the effect of the ARC intervention on youth outcomes and the mediating role of organizational priorities as a mechanism linking the ARC intervention to outcomes. Fourteen community-based mental health agencies in a midwestern metropolis along with 475 clinicians and 605 youth (ages 5-18) served by those agencies were randomly assigned to the 3-year ARC intervention or control condition. The agencies' priorities were measured with the ARC Principles Questionnaire (APQ) completed by clinicians at the end of the intervention. Youth outcomes were measured as total problems in psychosocial functioning described by their caregivers using the Shortform Assessment for Children (SAC) at 6 monthly intervals. The rate of improvement in youths' psychosocial functioning in agencies assigned to the ARC condition was 1.6 times the rate of improvement in agencies assigned to the control condition, creating a standardized difference in functioning of d = .23 between the 2 groups at the 6-month follow-up. The effect on youth outcomes was fully mediated by the alignment of organizational priorities described in the 5 ARC principles (d = .21). The ARC organizational intervention improves youth outcomes by aligning organizational priorities with the 5 ARC principles. The findings suggest that organizational priorities explain why some community mental health agencies are more effective than others. (PsycINFO Database Record

Preparation and Performance of Cu-Cr Contact Materials for Vacuum Switches with Low Contact Pressure

Insufficient anti-welding properties limit the application of Cu-Cr contact material in vacuum switches with low contact pressure. The CuCr-W-C alloys that are prepared are for decreasing welding tendencies and keeping the voltage withstand by addition of W and C elements. It is found that the average welding force of CuCr-W-C alloys is reduced more than 50% compared with that of the Cu50 Cr50 alloy. Especially for CuCrW3.0C0.3 and CuCrW1.0C0.5, the welding forces reduce to only 10% of Cu50Cr50. Arc erosion areas of CuCr-W-C alloys are enlarged by five times more than that of the Cu50Cr50 alloy in the same arcing conditions. The results of type tests were qualified. The results suggested that the CuCrW2.0C1.0 alloy could be used in vacuum switches with low contact pressure to replace the W-Cu type contacts.

The modelling of an SF6 arc in a supersonic nozzle: II. Current zero behaviour of the nozzle arc

The present work (part II) forms the second part of an investigation into the behaviour of SF6 nozzle arc. It is concerned with the aerodynamic and electrical behaviour of a transient nozzle arc under a current ramp specified by a rate of current decay (di/dt) before current zero and a voltage ramp (dV/dt) after current zero. The five flow models used in part I [] for cold gas flow and DC nozzle arcs have been applied to study the transient arc at three stagnation pressures (P0) and two values of di/dt for the current ramp, representing a wide range of arcing conditions. An analysis of the physical mechanisms encompassed in each flow model is given with an emphasis on the adequacy of a particular model in describing the rapidly varying arc around current zero. The critical rate of rise of recovery voltage (RRRV) is found computationally and compared with test results of Benenson et al []. For transient nozzle arcs, the RRRV is proportional to the square of P0, rather than to the square root of P0 for DC nozzle arcs. The physical mechanisms responsible for the strong dependence of RRRV on P0 have been investigated. The relative merits of the flow models employed are discussed.

Laboratory study of carbonaceous dust and molecules of astrochemical interest

In this paper are reviewed some research works dedicated to the study of carbonaceous dust and molecules of astrochemical interest. First of all it is discussed the carbon arc through which it is possible to produce carbon soot and fullerenes under helium but also many other different products just changing the arcing conditions. For example, when the carbon arc is struck in an hydrocarbon solvent it is possible to produce and trap polyynes in the solvent. Monocyanopolyynes and dicyanopolyynes can be produced as well by selecting the appropriate conditions. Amorphous carbon soot or partially graphitized carbon black can be produced with the carbon arc. Fullerenes were found in space thanks to the reference infrared spectra and the absorption cross sections which were determined in laboratory. Fullerenes are readily reactive with hydrogen yielding fulleranes the hydrogenated fullerenes. Furthermore fullerenes react with PAHs and with iron carbonyl yielding adducts. All these fullerene derivatives were synthesized and their reference spectra recorded in laboratory. It was proposed that petroleum fractions can be used as model substrates in the explanation of the carriers of the AIB (Aromatic Infrared Bands) observed in protoplanetary and planetary nebulae and the UIE (Unidentified Infrared Bands) found in the interstellar medium.

Importance of Electrodes Slipping Algorithm for the Ferrosilicon Smelting Process

The electric arc is one of the most unstable parts of the electrical circuit of submerged-arc furnaces in the ferrosilicon smelting process. In the carbothermal silica reduction electric arc has an important role as a high temperature heat source, and its presence is essential for the proper ferrosilicon process flow. Presence of the of electric arc and temperature conditions of the ferrosilicon process have a direct relationship with position of the electrodes tip and electrodes slipping. In the ferroalloy industry position of electrodes tip as similar as metallurgical parameters of the process are not directly measured. Most often these assessments are still based to a large extent on intuition and experience operating staff of the furnaces, and have qualitative and subjective character. In order to check the existing algorithm of electrodes slipping was carried out statistical studies of the FeSi75 ferrosilicon smelting process. The study was conducted at discrete intervals ∆t = 8h using data recorded by the furnace computer measuring system and methods of statistical data processing. It was found that the size of the electrodes slipping, and Cfix ratio in the feed are correlated and are among the most important parameters which have an impact on the technical and economic indicators of the process.

Char Trace Analysis of Composite Wood Floor under Different Heating Conditions

Under different heating conditions, the composite wood floor and pine carbonization samples were prepared, and the charring surface morphology, crack width, carbonization depth and average charring rate were compared and analyzed. The results show that under the thermal radiation condition, the carbonization of composite wood floor is the most serious, and cracks distributed radially; under the arc condition, the compound wood floor is difficult to ignite, and the carbonization layer is shallow; small amount spilled gasoline combustion has little effect on carbonization degree, but the char is obvious at the corner; at the same heating condition, the carbonization degree of pine was more serious than the composite wood floor, and the carbonized surface morphology had significant differences.

A prediction model of layer geometrical size in wire and arc additive manufacture using response surface methodology

Wire and arc additive manufacture has received much concern for its unique advantages in fabrication of large size near net shape components. But the flexibility nature of free arc and time-varying environmental conditions synergistically make shaping path complicated and mutable. In this paper, central composite rotatable experimental design was applied to clarify the mutual relation between input variables (peak current, wire feed speed, and travel speed) and their responses (bead height and width). Moreover, a predicting model was developed, and the validity of the model has been checked by analysis of variance (ANOVA) technique. By using the developed mathematical model, the bead height and width of a single layer are predicted with 95 % confidence level according to the pre-set process parameters. Vice versa, control strategies are proposed to keep the subsequent layer geometrical size unchanged from the former one. A set of process parameters with a desirability of 0.971 is advised basing on the model when the bead height is expected to be 2 mm and the optimum technological parameters, I p = 160A, v T = 0.23 m/min, v w = 4.91 m/min, have been verified by the confirmatory experiment.

Increasing clinicians' EBT exploration and preparation behavior in youth mental health services by changing organizational culture with ARC

ObjectiveClinician EBT exploration and preparation behavior is essential to the ongoing implementation of new EBTs. This study examined the effect of the ARC organizational intervention on clinician EBT exploration and preparation behavior and assessed the mediating role of organizational culture as a linking mechanism. MethodFourteen community mental health agencies that serve youth in a major Midwestern metropolis along with 475 clinicians who worked in those agencies, were randomly assigned to either the three-year ARC intervention or control condition. Organizational culture was assessed with the Organizational Social Context (OSC) measure at baseline and follow-up. EBT exploration and preparation behavior was measured as clinician participation in nine separate community EBT workshops held over a three-year period. ResultsThere was 69 percent greater odds (OR = 1.69, p < .003) of clinicians in the ARC condition (versus control) attending each subsequent workshop. Workshop attendance in the control group remained under two percent and declined over three years while attendance in the ARC condition grew from 3.6 percent in the first workshop to 12 percent in the ninth and final workshop. Improvement in proficient organizational culture mediated the positive effect of the ARC intervention on clinicians' workshop attendance (a × b = .21; 95% CI:LL = .05, UL = .40). ConclusionsOrganizational interventions that create proficient mental health agency cultures can increase clinician EBT exploration and preparation behavior that is essential to the ongoing implementation of new EBTs in community youth mental health settings.

An Update of Spacecraft Charging Research in India: Spacecraft Plasma Interaction Experiments—SPIX–II

Arcing on spacecraft solar panels has been a major challenge since it was first observed in late 1970s. Scientists of leading scientific countries like USA, Japan, France, and others are working hard to understand various aspects of this charging-arcing phenomenon. Based upon the experimental simulation results, a few arc mitigation techniques have been developed. In 2003, the Indian Space Research Organization (ISRO) realized the necessity to develop an experimental setup for understanding the charging-arcing phenomenon on satellite's solar panels when parked in lower earth orbit (LEO) in the Space Plasma Interaction Experiments (SPIX) facility. The SPIX facility was jointly developed as a collaborative research project between the ISRO and the Institute for Plasma Research. In 2010, an initiative was taken for the upgradation of the SPIX facility for testing both LEO and geosynchronous earth orbit (GEO) satellite's solar panels by the following standard ISO 11221 experimental procedure and indigenously developed high-speed data acquisition and analysis system. Various types of solar panel coupons were tested in upgraded SPIX-II facility. Sample solar panel coupons used in the experiments can be categorized based on the types of solar cells and the configurations of solar cell that includes different interstring gaps and grouting. For LEO satellite coupons, depending upon the types of solar panel coupons, different bias voltages were applied and threshold voltage was determined. Threshold arc tests were done at different bias voltages and electron gun energies for GEO satellite's coupons. Arc rates and threshold voltages were measured for each type of solar panel coupon, which determined their durability and reliability in harsh environmental conditions. Grouted solar panel coupons had higher threshold voltage in both LEO and GEO worst environmental conditions. Results showed good repeatability and reproducibility for both LEO and GEO experiments. To measure sustained arc conditions, experiments were performed with different string voltages and string currents in both LEO and GEO environmental conditions. It was experimentally validated that the probability of temporary sustained arc or permanently sustained arc increases on increasing either string voltage or string current. In addition, an attempt is also made to understand the role of plasma curing of solar panel coupons and its impact on arc mitigation for GEO environment like space conditions.

A new arc detection method based on fuzzy logic using S-transform for pantograph–catenary systems

pantograph–catenary system is one of the critical components used in electrical trains. It ensures the transmission of the electrical energy to the train taken from the substation that is required for electrical trains. The condition monitoring and early diagnosis for pantograph–catenary systems are very important in terms of rail transport disruption. In this study, a new method is proposed for arc detection in the pantograph–catenary system based signal processing and S-transform. Arc detection and condition monitoring were achieved by using current signals received from a real pantograph–catenary system. Firstly, model based current data for pantograph–catenary system is obtained from Mayr arc model. The method with S-transform is developed by using this current data. Noises on the current signal are eliminated by applying a low pass filter to the current signal. The peak values of the noiseless signals are determined by taking absolute values of these signals in a certain frequency range. After the data of the peak points has been normalized, a new signal will be obtained by combining these points via a linear interpolation method. The frequency-time analysis was realized by applying S-transform on the signal obtained from peak values. Feature extraction that obtained by S-matrix was used in the fuzzy system. The current signal is detected the contdition as healthy or faulty by using the outputs of the fuzzy system. Furthermore the real-time processing of the proposed method is examined by applying to the current signal received from a locomotive.

Physical Modeling of Secondary Arcing at Environmental Pressures in the Range from Atmospheric to Vacuum

An electrical breakdown in the onboard equipment of orbital space vehicles is a consequence of multifactor physical process related to vacuum electronics, low-temperature plasma physics, and gas discharge. The problem becomes especially urgent in connection with the application of an onboard electrical network voltage of 100 V and higher that exceeds the arcing threshold. The given problem is being actively investigated for more than 10 years; as a result, a number of standards regulating measures on prevention of secondary arcing as a consequence of electrostatic breakdown are currently in force in the world. However, arcing caused by internal processes in onboard equipment without high-voltage initiation has not yet practically been studied, despite the existence of such problem that makes these investigations urgent. The present work contains results of experiments on registration of the threshold parameters, first of all, the pressure that determines the risk of secondary arcing in the presence of the plasma imitating the primary discharge plasma and caused by wire evaporation. Results of experiments confirm the expected decrease of the threshold breakdown voltage below the minima of the Paschen curve. Experimental approaches used in this work are of methodological interest for imitation of arcing conditions and testing of stability of the equipment against arcing in orbital space.