Stability of D. C. Arc Welding System

This paper deals with the stability of the D. C. arc welding system in which the electrode wire is fed with a constant speed. The system under consideration is described by nonlinear differential equations. The solutions of the equations are studied for various values of system parameters. The stability of solutions is investigated by considering the behavior of small variations from the steady solutions. From the analytical results, it may be inferred that the arc length is readily held almost constant by making use of a constant voltage power source, even if the feeding speed varies. It is useful, to some extent, to utilize the phaseplane analysis in investigating the transient states of arc. The methods of analysis presented in this paper may also be applicable to other welding systems which are described by differential equations of a like form

Stability of the Welding Arc in a Constant Feeding Speed System

This paper deals with some problems concerning the stability of the D. C. arc welding system in which the electrode wire is fed with a constant speed. The arc welding system may produce a self-sustained oscillation where the current and length of the arc vary slowly and periodically in the steady state. The welding system is described by nonlinear differential equations. The phase-plane analysis is applied to the study of the phenomena. A steady state having a constant arc length is correlated with a singular point. A self-sustained oscillation is then represented by a limit cycle in the phase-plane. From the analytical results, it may be inferred that the self-sustained oscillations occur due to the self-regulation peculiar to the arc in the case where the power source has a rising characteristic

In-situ ice and meteorological observations in the southern Sea of Okhotsk in 2001 winter: ice structure, snow on ice, surface temperature, and optical environments

The 2001-ice season in the Sea of Okhotsk was characterized by extraordinarily developed ice extent. During the period February 17 to 21, we conducted in-situ observations in the southern ice area with the icebreaker \u27Soya\u27. In this paper, we show the observational results, concerning the core sampling of about 1.3 m-thick ice, snow sampling, surface temperature, and solar radiation under clear sky conditions. It is shown that (1) the sampled ice core is composed entirely of granular ice, (2) the 30 cm-thick snow pack overlying sea ice is composed mainly of depth hoar and significant vertical gradients of δ^O and temperature are found within the snow, probably associated with the depth hoar formation, (3) surface temperatures as low as about -30°C are detected on snow-covered sea ice floes at nighttime under almost clear and light breeze conditions, (4) from the estimation of the turbidity coefficient, the atmosphere over the ice-covered area is considered to be significantly clean. Furthermore, the NOAA/AVHRR satellite data are used to estimate the surface temperature distribution in the southern Sea of Okhotsk. It is shown that these data are useful for discriminating thick ice floes

cDNA cloning and nucleotide sequence of rat muscle-specific enolase (ββ enolase)

AbstractThe nucleotide sequence of rat muscle-specific enolase cDNA was determined by sequencing three cDNA clones encoding this enolase isozyme. The nearly full-length cDNA consists of 13-bp 5′- and 84-bp 3′-noncoding regions and a poly(A) tail in addition to a 1302-bp coding region encoding a polypeptide composed of 434 amino acid residues. The deduced primary structure of this enolase isozyme is about 80% similar to those determined previously for rat neuron-specific and non-neuronal enolase isozymes. Southern blot analysis suggested strongly the existence of a single copy of the muscle-specific enolase gene per haploid genome. The mRNA for this enolase isozyme was detected in rat skeletal muscle on day 1 after birth and its level increased rapidly during 10–30 days after birth without any change in its size (1500 bases)

Bayesian phase difference estimation algorithm for direct calculation of fine structure splitting: accelerated simulation of relativistic and quantum many-body effects

Despite rapid progress in the development of quantum algorithms in quantum computing as well as numerical simulation methods in classical computing for atomic and molecular applications, no systematic and comprehensive electronic structure study of atomic systems that covers almost all of the elements in the periodic table using a single quantum algorithm has been reported. In this work, we address this gap by implementing the recently-proposed quantum algorithm, the Bayesian Phase Difference Estimation (BPDE) approach, to compute accurately fine-structure splittings, which are relativistic in origin and it also depends on quantum many-body (electron correlation) effects, of appropriately chosen states of atomic systems, including highly-charged superheavy ions. Our numerical simulations reveal that the BPDE algorithm, in the Dirac--Coulomb--Breit framework, can predict the fine-structure splitting of Boron-like ions to within 605.3 cm$^{-1}$ of root mean square deviations from the experimental ones, in the (1s, 2s, 2p, 3s, 3p) active space. We performed our simulations of relativistic and electron correlation effects on Graphics Processing Unit (GPU) by utilizing NVIDIA's cuQuantum, and observe a $\times 42.7$ speedup as compared to the CPU-only simulations in an 18-qubit active space.Comment: 7+4 pages, 2 figure

Synthesis of p-type ZnO thin films using co-doping techniques based on KrF excimer laser deposition

Abstract Preparation of N-doped ZnO thin films was attempted using various co-doping methods. A ZnO:Ga (Ga O of 5 wt.%) target 2 3 was ablated in NO gas by pulsed laser deposition (PLD). In addition, a nitrogen ion gun and an ECR nitrogen plasma source were used as post-N-doping treatment of undoped ZnO films. Optical emission from elemental Zn I, Ga I and O I, as well as from N molecules, was identified in the plasma plume. The structural, optical and electrical properties of these synthesized films 2 were investigated. All films show n-type conduction, with resistivity in the range 10 -10 V cm and carrier density from y3 y2 10 to 10 cm

Older boys benefit from higher initial prednisolone therapy for nephrotic syndrome

Older boys benefit from higher initial prednisolone therapy for nephrotic syndrome.BackgroundA long course of the initial prednisolone therapy has been shown to be more effective than standard-course therapy in reducing relapse rates in children with idiopathic nephrotic syndrome, but it is commonly accompanied by corticosteroid toxicities. There has been no study on prednisolone dosage for the effective treatment of nephrotic syndrome.MethodsSixty-eight children (42 boys and 26 girls) with an initial attack of nephrotic syndrome were randomly allocated into two different long-course treatment groups. Patients in Group 1 received a daily prednisolone dose of 60 mg/m2 for six weeks, followed by an alternate-day dose of 40 mg/m2 for six weeks. Patients in Group 2 had a daily dose of 40 mg/m2 instead of 60 mg/m2.ResultsFour children in each group did not respond within six weeks. Group 1 was associated with a significantly earlier response but more frequent corticosteroid toxicities than Group 2. Boys in Group 1 had a higher rate of sustained remission than boys in Group 2 (P = 0.0073), especially boys four years old or more (P = 0.0027), but girls did not show a significant difference (P = 0.863). Boys four years old or more in Group 1 had a course of frequent relapsing less often than those in Group 2 (2 of 13 vs. 6 of 8, P = 0.0075).ConclusionThese findings indicate that efficient prednisolone doses may vary between sexes and ages, and that a higher initial prednisolone therapy may be of greater benefit to older boys

Transcutaneous Electrical Nerve Stimulation on the PC-5 and PC-6 Points Alleviated Hypotension after Epidural Anaesthesia, Depending on the Stimulus Frequency

Neuraxial blockade causes arterial hypotension. Transcutaneous electrical nerve stimulation (TENS) at the Neiguan (PC-6) and Jianshi (PC-5) reduces the severity of hypotension after spinal anaesthesia, but did not clarify the optimal stimulus frequency. We hypothesized that the stimulus frequency of TENS at the PC-6 and PC-5 points would influence the severity of hypotension after epidural anaesthesia. 65 ASA I or II male patients presenting for inguinal hernia repair were randomized to five groups: the control group received no treatment; the 2 Hz, 10 Hz, 20 Hz, and 40 Hz groups received TENS at a frequency of 2 Hz, 10 Hz, 20 Hz, and 40 Hz, respectively. The lowest SBP was significantly higher in the 40 Hz group [the control, 84 (74–110) mmHg; the 2 Hz, 96 (62–116) mmHg; the 10 Hz, 100 (68–110) mmHg; the 20 Hz, 96 (64–115) mmHg; the 40 Hz, 104 (75–140) mmHg: P = 0.004]. Significantly less patients experienced hypotension in the 40 Hz group [the control, 78%; the 2 Hz, 43%; the 10 Hz, 38%; the 20 Hz, 38%; the 40 Hz, 8%: P = 0.008]. TENS on the PC-6 and PC-5 points reduced the severity and incidence of hypotension after epidural anaesthesia, depending on the stimulus frequency