A potential solution to GMAW gas flow optimisation

A number of self-regulating shielding gas valves have been developed to synchronise the shielding gas flow rate to the welding current being used in the gas metal arc welding process (GMAW). These valves make claims to reduce the shielding gas consumption by up to 60%. One such system, the Regula® EWR Pro, has undergone detailed evaluation in an effort to fully understand the benefits that could be obtained. This electromagnetically controlled system necessitates around an extremely fast response valve, which opens and closes continually throughout the welding process. This creates a pulsing of the shielding gas, further reducing consumption whilst maintaining optimal shielding gas flow. The unit has been identified to reduce the initial gas surge at weld initiation and results in a virtually instant decay of gas flow at weld termination. These particular characteristics have been found to be ideally suited to saving shielding gas when carrying out intermittent or stitch welding. It was established that the use of this valve generated deeper penetration in fillet welds, which in turn has highlighted the potential to increase the welding speed, therefore further reducing gas consumption. In addition, a computational model has been developed to simulate the effects of cross drafts. The combination of reducing the gas surge and slow decay with faster welding has been shown to meet the drive for cost savings and improving the carbon footprint

Time and the Physical Universe

(This information was taken from the Distinguished Scientist Lecture Series Program 1989-1990). Norman F. Ramsey is the Higgins Professor ofPhysics at Harvard University. He has been a Harvard faculty member since 1947. Norman Ramsey received his A.B. and M.A. from Columbia University and degrees from Cambridge University. In1940 he received aPh.D. from Columbia University for molecular beam studies of rotational magnetic moments of molecules. He was awarded an Sc.D. by Cambridge University in1954 and by Oxford University in1973, as well as honorary D.Sc.\u27s from Case-Western Reserve University, Middlebury College, and Rockefeller University. After periods at the Carnegie Institution of Washington, the University of Illinois, the MIT Radiation Laboratory, and Los Alamos, he became an Associate Professor atColumbia University. He was executive secretary of the group of scientists who established Brookhaven National Laboratory and was the first chairman of its physics department. Norman Ramsey has been a Guggenheim Fellow and was the George Eastman Professor at Oxford University in1973-7 4. He was chairman of the physics section of the American Association for the Advancement of Science in 1977 -78 and president of the American Physical Society in 1978-79. From 1966 to 1981 he was president of the Universities Research Association, which operates the Fermi National Accelerator Laboratory. He has been a trustee of the Carnegie Endowment for International Peace since 1962 and of Rockefeller University since 1977. Since 1980 he has been chairman of the Board of Governors of the American Institute of Physics and since 1985 he has been president of the United Chapters of Phi Beta Kappa. Dr. Ramsey is a member of the American Physical Society, the Institute of Electrical and Electronics Engineers, the American Philosophical Society, the American Academy of Arts and Sciences, and the National Academy of Sciences. He received the Presidential Certificate of Merit in 1950, the E.O. Lawrence Award in 1960, the Davisson-Germer Prize in 1974, the IEEE Medal of Honor in 1984, the 1980 Columbia Award for Excellence inScience, and the 1987 IEEE Centennial Medal. Dr. Ramsey has also received the Monie Ferst Award, the Rabi Prize, the Mumford Premium in 1985, the Compton Medal in 1986, the Oersted Medal, and the National Medal of Science in 1988. Dr. Ramsey\u27s books include Experimental Nuclear Physics, Nuclear Moments, Molecular Beams, and Quick Calculus! His Work: Dr. Ramsey has developed theories and experimental methods in fields ranging from particle physics to molecular beams. He and his associates have made precision measurements of the electric and magnetic properties of nucleons, nuclei, atoms, and molecules. He is well known for his work on atomic and molecular beams, including the invention of the hydrogen maser.https://digitalcommons.bard.edu/dsls_1989_1990/1004/thumbnail.jp

Systematic study of effect of cross-drafts and nozzle diameter on shield gas coverage

A shield gas flow rate of 15–20 L min21 is typically specified in metal inert gas welding, but is often adjusted to as high as 36 L min21 by welders in practice. Not only is this overuse of shield gas wasteful, but uncontrolled high gas flows can lead to significant turbulence induced porosity in the final weld. There is therefore a need to understand and control the minimum shield gas flow rate used in practical welding where cross-drafts may affect the coverage. Very low gas coverage or no shielding leads to porosity and spatter development in the weld region. A systematic study is reported of the weld quality achieved for a range of shield gas flow rates, cross-draft speeds and nozzle diameters using optical visualisation and numerical modelling to determine the shield gas coverage. As a consequence of the study, the shield gas flow has been reduced to 12 L min21 in production welding, representing a significant process cost saving and reduced environmental impact with no compromise to the final weld quality

Effects of X-irradiation on Potassium Flux in Isolated Nerves

The purpose of this study, therefore, was threefold in nature: (1) to determine the effects of x-irradiation on the influx and efflux of potassium in compound nerve fibers (2) to attempt to relate the radiation-induced changes in electrical activity with potassium flux and (3) to use the information obtained to gain insight into the possible cellular site (s) of radiation insult to compound nerves

A computational fluid dynamic analysis of the effect of side draughts and nozzle diameter on shielding gas coverage during gas metal arc welding

Extensive experimental trials were conducted, emulating the conditions modelled, in order to validate the computational fluid dynamic results. Final results demonstrated that a more constricted nozzle was more effective at creating a stable gas column when subjected to side draughts. Higher shielding gas flow rates further reduce the gas column's vulnerability to side draughts and thus create a more stable coverage. The results have highlighted potential economic benefits for draught free environments, in which, the shielding gas flow rate can effectively be reduced

Determination of the Quadrupole Coupling Constant in the N^{14} Atomic Ground State

The zero-field hyperfine frequencies in the ground state of atomic N14 have been measured in a hydrogen maser with sufficient accuracy to resolve the quadrupole coupling constant B. The result is B=+1.32±0.20 Hz.Molecular and Cellular Biolog

Dimensions of Time

Humanities Research Group Working Papers 8 Time: whether we’ve too much time on our hands or no time to stop and think, whether time flies or marches slowly, whether we are clock watchers or don’t own a watch, perennially late or inevitably early, the nature of time preoccupies us all. It is fitting, then, that this volume, the last to appear in the century beginning with “nineteen,” should take as its theme “Dimensions of Time.” This volume, as have all in the series, examines a topic of contemporary interest from a variety of historical and disciplinary perspectives.https://scholar.uwindsor.ca/hrg-working-papers/1007/thumbnail.jp

Classical and Quantum Interaction of the Dipole

A unified and fully relativistic treatment of the interaction of the electric and magnetic dipole moments of a particle with the electromagnetic field is given. New forces on the particle due to the combined effect of electric and magnetic dipoles are obtained. Four new experiments are proposed, three of which would observe topological phase shifts.Comment: 10 pages, Latex/Revtex. Some minor errors have been correcte