Longer Arc Research Articles

Simulation of the Influence of the as-Deposited Wall Thickness on Arc Shape and Stability during Wire Arc Additive Manufacturing

The single-pass multi-layer depositing strategy is usually used to fabricate thin-wall structures with wire and arc additive manufacturing (WAAM) technology. Various deposited wall thicknesses often lead to a change in arc shrinkage in the wall thickness direction, which affects the arc shape and stability, and even the microstructure and properties. To systematically study the effect of wall thickness (δ) on arc shape and stability, 3D numerical models were established, with wall thickness varying from 1 to 14 mm during the WAAM process. The characteristics of the arc shape, temperature field, velocity field, current density, and the electromagnetic force were investigated. When δ is smaller than the arc diameter (Φ), the thinner wall will result in a longer arc along the deposition direction. When δ is greater than the Φ, the arc shape tends to be a bell shape. When δ < Φ, the peak temperature in the arc centre, the peak current density, and the electromagnetic intensity along the welding direction decreased with the increase in the wall thickness. However, the opposite observations were found when δ < Φ. The simulation results are consistent with the actual arc shape collected and showed that when δ is slightly less than Φ, the forming quality of the deposited wall is the best. The research in this paper can fill the research gap and provide a theoretical basis for the matching selection of process parameters and wall thickness in WAAM applications.

Delivery and Deliverance: Religious Experiences of Childbirth in Eighteenth-Century America

AbstractThis paper argues that childbirth served as a prism for religious experience in early America, not just among the women who experienced it but also among the members of their households and communities. Examining childbirth as the source of religious experience can shed light on the social and physiological dimensions of early American spirituality by illuminating a religious culture of childbearing that shaped the piety of anyone who came into contact with it. We might expect that childbirth molded women's spirituality. But this article proposes that not just women but also others in their midst experienced religion differently because of their proximity to childbirth. Pregnancy, labor, and infant loss forced women and men to confront mortality and became means through which they carved out spiritual life, created ritual, and forged religious community. Using the body as a category of analysis, this paper reveals a space where the physical and spiritual persons intersect, and it argues that spiritual responses to childbirth as a physiological event were part of the longer arc of religious experience than we have previously appreciated. In doing so, it offers new ways to center women and gender in the narrative of early American religious history.

Banning Jewish “Extremist” Literature in Russia: Conversion and Toleration in Historical Perspective

In 2017, Russia’s Ministry of Justice banned a nineteenth-century book written by the German rabbi Markus Lehmann, labeling it extremist literature. This article places current Russian efforts to stamp out religious extremism in a broader historical context of imperial productions of tolerance and intolerance and the impact on religious minorities. It examines the case of Jews in the Russian Empire and post-Soviet Russia through the lens of religious conversion, forced baptisms, and freedom of conscience in the realm of apostasy. Lehmann’s book, characteristic of nineteenth-century Orthodox Jewish historical fiction in German, used the historical memory of forced conversions of Jews in medieval and early modern Europe to forge a new path to integration in tolerant, Protestant environs. This article offers a historical and literary reading of Lehmann’s banned book against the longer arc of imperial Russian toleration and conservative appropriations of toleration for discrimination against minorities.

Gas Metal Arc Root Welding of Pearlitic Rails Using Magnetic Arc Deflection

Magnetic arc deflection was applied to improve gas metal arc root welds on R260 pearlitic rail steel foot samples. During laboratory welding trials parameter optimization was carried out which comprised the welding current, voltage and speed, layer sequence, filler wire diameter, and the external magnetic field. Results were evaluated by visual inspection, and the lateral and diagonal penetration in cross-sections, as well as the microstructure and the hardness in the HAZ. Additionally, the influence of the external magnetic field on the process was studied using a high-speed camera. Overall best results were finally obtained in high welding current spray arc mode (380-400A) with the 1,6mm solid wire and at high welding speed (65cm/min) and two pass per layer sequence, in combination with maximum 30mT magnetic flux density and increased welding voltage (30-31V) for longer arc. A continuously well-formed root with sufficient lateral penetration was achieved and a smooth transition from base metal to weld metal at the lower edges could be achieved. Inside base metal HAZ the microstructure was fully pearlitic and no soft zone occurred. Furthermore, the size of the HAZ was in comparison to aluminothermic weld reduced by more than 75% in comparison to an AT rail weld.

A study on horizontal stud welding by using steel stud for flat welding

ABSTRACTIn recent years, manufacturing sites have strongly requested for the steel stud with large diameter to be welded in the horizontal position, which is difficult because of gravity. In this study, the steel stud of 19 mm in diameter was welded horizontally to the mild steel plate by using ferrule for usage in flat position. As results two kinds of weld defect were observed; lack of fusion and blowhole. The former occurred in the welding condition of too small or too large heat input, and the latter did in the range of longer arc time. Therefore, the suitable welding condition could be found in the large current and shorter arc time. When the areal ratio of weld defect to the cross section of stud was lower than 10 percent, the welded joint had enough statical strength.

How Systems Cohere: Niira Radia in 2017

Why do mediatized political scandals fail to effect discernable transformations of a systemic kind? This article offers one possible answer to this question by revisiting the media event known as “the Radia tapes scandal” to think through the reasons why, despite its explosive contents, the scandal changed little in the day-to-day workings of Indian political life. I argue that the noneventful temporality of mediatized political scandals is important to attend to because it is in the sphere of the everyday that we might be able to discern how corruption mediates relations between states and publics. That is to say: scandals do not change systems because systems rely on corruption, leaks, and information flows to render themselves stable. By fixating on leaks as a political tool, we run the risk of taking a system’s self-representation of disorder at face value. In making these points, I historicize the Radia affair within a longer arc of mediated corruption scandals in India and then juxtapose the leaks themselves to an artwork by the collective, CAMP.

The screening mammography paradox: better when found, perhaps better not to find

The screening mammography paradox: better when found, perhaps better not to find

Stiff arc length constraint in nonlinear FEA

Arc length constraints enable iterative solution procedures in nonlinear finite element analysis to converge even at critical points. The arc length constraint replaces the conventional m×m stiffness matrix with an augmented (m+1)×(m+1) stiffness matrix. Its use is referred to as arc length control, in contrast to load control which furnishes the conventional stiffness matrix. In the current article, an apparently new arc length constraint is introduced. It identifies arc length parameters maximizing the stiffness (absolute value of the determinant) of the augmented matrix. The parameters, viewed as a vector, must be perpendicular to the rows of the stiffness matrix, likewise considered vectors. The augmented stiffness matrix is nonsymmetric and lacks the small bandwidth of the conventional stiffness matrix. However, using a block triangularization, it is demonstrated that a solution may be attained by standard finite element operations, namely triangularization of a banded nonsingular portion of the stiffness matrix followed by forward and backward substitutions involving banded lower and upper triangular matrices. The proposed constraint is expected to permit convergence under longer arc lengths than currently implemented methods. A simple example is given illustrating the application of the constraint.

P-148: Consistent Performance of Dual Paraboloid Reflector System with Respect to Arc-Gap Variations as Applied in Projection Displays

The Wavien dual paraboloid reflector system is an imaging reflector system having a 1:1 magnification characteristic that allows focusing the light from the arc into the target light pipe with practically no change in etendue. This results in a more consistent coupling efficiency from burner to burner. Furthermore, for a given etendue requirement the system allows the use of burners with longer arc gaps without degrading the coupling efficiency. Implication is that lamps with longer arc gaps renders to a potential of longer service life, ease in manufacturing, and lower production cost. This paper presents the ASAP simulations and experimental results as they are applied to projection systems.

Insulation recovery characteristics of 500 kV class dc insulator assemblies after arc extinction

The insulation recovery characteristics of 500-kV-class dc insulator assemblies were measured. Switching impulse voltage was applied to a tension insulator assembly and three kinds of suspension insulator assemblies (V-, Y-, and I-arranged) following arc extinction. Arc current ranged from 400 A to 4000 A and arc duration from 0.1 s to 0.4 s. (1) All insulator assemblies show slow insulation recovery after arc extinction up to an impulse withstand voltage of 100 to 200 kV. The insulation recovery rates increase near the impulse withstand voltage of 500 kV. (2) At arc current of 400 to 4000 A, for a duration of 0.1 s, the recovery rate for all insulator assemblies decreases with increases in arc current. This is believed to be due to the increases in the postarc gas temperature caused by the increased arc current. (3) When the arc duration is increased from 0.1 s to 0.2 s at a current of 4000 A, the insulation recovery of the V- and Y-arranged assemblies is delayed by 0.05 s. This is believed to be due to the increases in the temperature of postarc gas caused by the longer arc duration. (4) By measuring the insulation recovery characteristics of the tension insulator assembly and three kinds of suspension insulator assemblies with an arc current of 4000 A and an arc duration of 0.1 s, the minimum value of nonvoltage time for a 500-kV dc transmission line is calculated to be 0.17 s. © 1999 Scripta Technica, Electr Eng Jpn, 129(3): 29–39, 1999

Multiple, large deletions in rat mitochondrial DNA: evidence for a major hot spot

This study identified 33 different deletions in mitochondrial DNA from four aging Fischer-344 rat brains and from a cultured rat lymphoma cell line (Nb2 cells). The deletions were located in the longer arc between the heavy and light strand origins of replication. PCR products that spanned across the deleted regions were sequenced, and deletions ranging between 6548 bp and 9977 bp in length were identified. Short direct repeats of ≤ 8 bp were present at the end points of all but one of the deletions. The remaining deletion contained, instead, a near-perfect direct repeat ( 9 10 bp) within two base pairs of its end points. In 24 of the deletions, a sequence equivalent to one member of the paired direct repeats was lost with the deleted segment. In the remaining nine, either more or less of the base pairs of a single repeat were lost. Twelve of the 33 different deletions terminated on one side at a common locus (major hot spot) of 5 bp in length, located at the 5′ end of the tRNA Thr gene. The opposite ends of these 12 deletions were at different sites. The hot spot was located in a region of the mtDNA with strong potential for secondary structure and was flanked by a pair of AT-rich sequences. The utilization of the hot spot as an end point for deletions appeared to be widespread in that it was represented in 1 3 − 1 2 of the deletions characterized in each of the five mtDNA sources examined. In addition, several minor hot spots, where one end of two or three different deletions coincided, were also identified.

Long Arc Shrouding—A Reliability Improvement for Untuned Steam Turbine Blading

An approach to the design and modification of untuned variable speed steam turbine exhaust blading has been found to be highly successful in eliminating fatigue failures due to the first tangential in-phase mode resonance. The approach consists of butt-welding the shrouds on the short arc blade groups to form a substantially longer arc length. The result is a significant reduction in vibratory stress at resonant speeds. Because of the ease with which the approach can be implemented in the field, backfitting is highly attractive to turbine operators. Availability benefits to the marine, utility, petrochemical, refining, industrial and commercial fields are anticipated.

The measurement of latitude, time, and height variations at a single laser tracking station

Recent analyses of laser data for determining variation of latitude have been based on apparent variations in the orbital inclination of the satellite derived from short orbital arcs of 6–8 hours. An alternative method, based on the daily adjustment of the station position to a much longer arc of 2 or 3 weeks has recently been developed and tested. In the new method a long orbital arc is derived from many days of data and is subsequently used as a reference orbit for the adjustment of the position of the station (only) on each day of the long arc for which tracking data are available. This new technique appears to give slightly better results when it is applied to a test period in August 1970, with the added advantage that earth rotation measurements can be derived from the same data at the same time. The results for the test period indicate a precision of 74 cm in variation of latitude and 0.81 ms in monitoring the earth's rotation with 6 hours of data.

Long waves observed in the Kamchatka earthquake of November 4, 1952

The responses of conventional seismographs are such that earthquake waves in the period range of about 5 to 20 seconds are written with such large amplitudes an the seismograms that longer period waves cannot be observed. Consequently, in order to increase the observable range to substantially longer periods, I developed an electromagnetic strain seismograph having a recording galvanometer of three minutes period and an equivalent pendulum magnification factor for surface waves of 20. The first great earthquake which has occurred since this seismograph combination was put into service was the Kamchatka shock of 1952, November 4. Studies of the aftershock sequence of this earthquake have indicated that in the principle shock faulting extended approximately 1,000 km with an average slip of about 15 feet. Figure 1 shows a portion of the seismogram of this earthquake written with the new instrument. The most prominent event on this record is the G1 wavelet, which is a horizontally polarized surface wave with no vertical component. Although the G wavelet is a Love wave, its frequency components · all lie in that part of the dispersion curve which is essentially flat, and, consequently, the wavelet propagates without substantial change of shape. Thus, although the duration of G2 which has traveled over the longer arc has been increased to 180 seconds owing to differentially greater absorption of the higher frequencies, its shape is not changed. The apparent change in shape is a result of the instrument response characteristics. The response to the 60-second pulse of G1 is proportional to ground particle displacement, since the pulse frequency components are mainly greater than the galvanometer frequency. With G2, the frequencies cluster about the frequency of the galvanometer, and the over-all response is thus approximately proportional to the ground particle velocity. The G2 pulse as written on the seismogram is thus the first time derivative of the G1 pulse, indicating identity of shape for the two. The time of travel for a complete circuit around the earth for the G wave was measured on the seismogram by comparing the arrival time intervals of G4–G2 and G3–G1 . It is 152.3 minute This corresponds to a surface velocity of 4.38 km per second, which is lower than the value to be expected for a shear wave which penetrates as deeply as the G wave. Figure 2 is a portion of the seismogram containing G1 and R1.

III. On the reversal of the lines of metallic vapours. No. VI

The experiments described in the following communication were made with the electric arc, and in lime crucibles, or in crucibles of a highly calcareous sandstone, kindly supplied to us by Messrs. Johnson, Matthey, and Co., as described in our fourth communication on this subject; but for some of them we used, instead of a galvanic battery, a magneto-electric machine producing a much more powerful current and a much longer arc. The experiments with this machine were made, through the kindness of Dr. Tyndall, at the Royal Institution, and we are indebted to Messrs. Siemens both for the working of the machine and for sparing to us the services of a skilled engineer, in he person of Mr. Oscar Doermer, whose assistance was most valuable. We wish to express our thanks to all these gentlemen for the facilities they so readily granted to us.