A study of the efficacy of flame electrical resistance for standoff measurements during the oxyfuel cutting process

2021 ◽  
pp. 1-11
Author(s):  
Christopher R. Martin ◽  
Alexandrina Untaroiu ◽  
Kemu Xu ◽  
S M Mahbobur Rahman
Keyword(s):  
Measurement Uncertainty ◽  
Electrical Resistance ◽  
Path Length ◽  
Reaction Rate ◽  
Potential Method ◽  
Work Piece ◽  
Flame Resistance ◽  
Free Electrons ◽  
Careful Scrutiny ◽  
Cut Quality

Abstract This is a study of the suitability of preheat flame electrical resistance as a potential method for measuring the standoff distance an oxyfuel cutting torch and a work piece. Careful scrutiny of forty seven (47) individual experiments demonstrate that when cut quality is good, there is a linear repeatable relationship between the two with uncertainty about ± .3mm (.015in). As the cut quality degrades, the formation of top-edge dross reduces the electrical path length in the flame, and momentary reduction in the reaction rate in the kerf reduces the free electrons in the flame, causing rises in flame resistance. In these conditions, measurement uncertainty reduces to ± 1mm (.040in) or worse.

A Study of the Efficacy of Flame Electrical Resistance for Standoff Measurements During the Oxyfuel Cutting Process

2021 ◽  
Author(s):  
Christopher R. Martin ◽  
Alexandrina Untaroiu ◽  
Kemu Xu ◽  
S. M. Mahbobur Rahman
Keyword(s):  
Measurement Uncertainty ◽  
Electrical Resistance ◽  
Path Length ◽  
Reaction Rate ◽  
Potential Method ◽  
Work Piece ◽  
Flame Resistance ◽  
Free Electrons ◽  
Careful Scrutiny ◽  
Cut Quality

Abstract This is a study of the suitability of preheat flame electrical resistance as a potential method for measuring the standoff distance an oxyfuel cutting torch and a work piece. Careful scrutiny of forty seven (47) individual experiments demonstrate that when cut quality is good, there is a linear repeatable relationship between the two with uncertainty about ± .3mm (.015in). As the cut quality degrades, the formation of top-edge dross reduces the electrical path length in the flame, and momentary reduction in the reaction rate in the kerf reduces the free electrons in the flame, causing rises in flame resistance. In these conditions, measurement uncertainty reduces to ± 1mm (.040in) or worse.

scholarly journals The theory of the transport phenomena in metals

1950 ◽  
Vol 203 (1072) ◽  
pp. 75-98 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Electric Power ◽  
Electrical Resistance ◽  
Free Electrons ◽  
Thermo Electric ◽  
Intermediate Temperature Range ◽  
Order Of Magnitude ◽  
Impure Metal ◽  
Ionic Lattice ◽  
The Ideal

Exact expressions, valid for all temperatures, are obtained in the form of infinite determinants for the electrical conductivity, the thermal conductivity and the thermo-electric power of a degenerate gas of quasi-free electrons interacting with the ionic lattice of a metal. It is shown that the values of the electrical and thermal conductivities, in general, exceed the values given by the approximate interpolation formulae due to Bloch (1930), Wilson (1937) and others, and, in particular, that the Grüneisen-Bloch formula for the ideal electrical resistance is appreciably in error in the region close to the Debye temperature. It is further shown that the residual and ideal resistances of an impure metal are not strictly additive in the region where the two are of the same order of magnitude. The behaviour of the thermal conductivity is shown to agree qualitatively with the discussion based on Wilson’s formula given by Makinson (1938); the numerical values of the thermal conductivity, however, are increased appreciably, particularly for an ideal metal at low temperatures. The thermo-electric power is also discussed, but no simple results can be given for the intermediate temperature range.

scholarly journals Method of kurtosis in estimating the measurement uncertainty during calibration of the electrical resistance measures using a potentiometer

2021 ◽  
pp. 30-34
Author(s):  
Igor Zakharov ◽  
Olesia Botsiura ◽  
Valerii Semenikhin
Keyword(s):  
Measurement Uncertainty ◽  
Electrical Resistance ◽  
Voltage Drop ◽  
Measurement Model ◽  
Standard Uncertainty ◽  
The Monte Carlo Method ◽  
Resistance Measure ◽  
Distribution Laws ◽  
Single Size ◽  
Good Agreement

Calibration of electrical resistance measures is considered by the indirect method, which is realized through measuring the voltage drop across the series-connected reference and calibrated resistors. The biases of the estimates of the measurand and the combined standard uncertainty due to the nonlinearity of the measurement model were calculated. The distribution laws of the input quantities in the calculation of the expanded uncertainty were taken into account by the kurtosis method. An example of measurement uncertainty evaluating during calibration of single-size electrical resistance measure R331 with a nominal resistance of 1000 Ω by comparing its value using a potentiometer R345 with the value of the calibrated reference standard is considered. Estimates of the measurand and its standard and expanded uncertainties obtained using the proposed method showed good agreement with the estimates obtained using the Monte Carlo method.

scholarly journals Oxidative Photocyclization of Aromatic Schiff Bases in Synthesis of Phenanthridines and Other Aza-PAHs

2020 ◽  
Vol 21 (16) ◽  
pp. 5868
Author(s):  
Martin Kos ◽  
Jaroslav Žádný ◽  
Jan Storch ◽  
Vladimír Církva ◽  
Petra Cuřínová ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Reaction Rate ◽  
Potential Method ◽  
Biologically Active ◽  
Aromatic Rings ◽  
Order Of Magnitude ◽  
Substituent Constants ◽  
Aromatic Imines ◽  
Aromatic Systems ◽  
Electron Donating Groups

The oxidative photocyclization of aromatic Schiff bases was investigated as a potential method for synthesis of phenanthridine derivatives, biologically active compounds with medical applications. Although it is possible to prepare the desired phenanthridines using such an approach, the reaction has to be performed in the presence of acid and TEMPO to increase reaction rate and yield. The reaction kinetics was studied on a series of substituted imines covering the range from electron-withdrawing to electron-donating substituents. It was found that imines with electron-withdrawing substituents react one order of magnitude faster than imines bearing electron-donating groups. The 1H NMR monitoring of the reaction course showed that a significant part of the Z isomer in the reaction is transformed into E isomer which is more prone to photocyclization. The portion of the Z isomer transformed showed a linear correlation to the Hammett substituent constants. The reaction scope was expanded towards synthesis of larger aromatic systems, namely to the synthesis of strained aromatic systems, e.g., helicenes. In this respect, it was found that the scope of oxidative photocyclization of aromatic imines is limited to the formation of no more than five ortho-fused aromatic rings.

The Electrical Resistance of Dilute Solid Solutions

1936 ◽  
Vol 32 (2) ◽  
pp. 281-290 ◽  
Author(s):  
N. F. Mott
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
Solid Solutions ◽  
Electrical Resistance ◽  
Unit Volume ◽  
Effective Number ◽  
Free Electrons ◽  
Mechanical Explanation ◽  
Image Position ◽  
Matthiessen's Rule

1. As is well known, the electrical resistance of a metal is very greatly in-creased by the addition of a second metal with which it forms a solid solution. The increase Δρ in the resistivity due to the addition of a small percentage of the second metal is in general independent of the temperature (Matthiessen's rule), though there are oertain exceptions (e.g. Cr in Au). The quaritum-mechanical explanation of both these facts was first given by Nordheim, and may be expressed as follows: the electrical conductivity of any metal may be written in the formwhere τ is the “time of relaxation”, equal to half the time between collisions, and N is the effective number of free electrons per unit volume: hence, for the resistivity, we have

scholarly journals Influence of tube volume on measurement uncertainty of GM counters

2010 ◽  
Vol 25 (1) ◽  
pp. 46-50 ◽  
Author(s):  
Koviljka Stankovic ◽  
Milos Vujisic ◽  
Ljubinko Delic
Keyword(s):  
Measurement Uncertainty ◽  
Current Pulse ◽  
Electrical Breakdown ◽  
Radiation Detection ◽  
Random Variable ◽  
Radiation Energy ◽  
Radiation Detectors ◽  
Free Electrons ◽  
Elementary Processes ◽  
Reading System

GM counters are often used in radiation detection since they generate a strong signal which can be easily detected. The working principal of a GM counter is based on the interaction of ionizing radiation with the atoms and molecules of the gas present in the counter's tube. Free electrons created as a result of this interaction become initial electrons, i. e. start an avalanche process which is detected as a pulse of current. This current pulse is independent of the energy imparted on the gas, that being the main difference between a GM counter and the majority of other radiation detectors. In literature, the dependence on the incidence of radiation energy, tube's orientation and characteristics of the reading system are quoted as the main sources of measurement uncertainty of GM counters. The aim of this paper is to determine the dependence of measurement uncertainty of a GM counter on the volume of its counter's tube. The dependence of the pulse current on the size of the counter's tube has, therefore, been considered here, both in radial and parallel geometry. The initiation and expansion of the current pulse have been examined by means of elementary processes of electrical discharge such as the Markov processes, while the changes in the counter's tube volume were put to test by the space - time enlargement law. The random variable known as the 'current pulse in the counter's tube' (i. e. electrical breakdown of the electrode configuration) has also been taken into account and an appropriate theoretical distribution statistically determined. Thus obtained theoretical results were then compared to corresponding experimental results established in controlled laboratory conditions.

Semiconductor Aspects of the Oxyfuel Cutting Torch Preheat Flame: Part I — Measurements Between Torch and Work

2020 ◽  
Author(s):  
Christopher R. Martin ◽  
Teresa Pond ◽  
Jacob Tomas ◽  
Jenna Schmit ◽  
Erikson Miguel ◽  
...  
Keyword(s):  
Voltage Characteristic ◽  
Chemical Activity ◽  
Work Piece ◽  
Ion Currents ◽  
Current Signal ◽  
Flame Resistance ◽  
Current Voltage Characteristic ◽  
Secondary Ions ◽  
Current Voltage ◽  
Sinusoidal Current

Abstract This two-part paper presents precise measurements of the ion currents passing between the torch and work piece of the preheat flame of an oxyfuel cutting torch as a means for replacing contemporary sensing suites. Part I shows that the current-voltage characteristic of the flame exhibits sharp discontinuities common to semi-conductors that we study in various configurations including preheat, pierce, cut, and loss-of-cut. Standoff measurements are made by applying a sinusoidal current signal between the torch and work piece while the resulting voltage amplitude is an indication of flame resistance. Uncertainties are estimated to range from 0.5mm to 1mm (.02in to .04in). Signals for ready-to-pierce and precursors for loss-of-cut are also produced due to the generation of secondary ions from chemical activity at the work piece.

The thermal and electrical conductivity of silver-palladium and silver-cadmium alloys at low temperatures

1956 ◽  
Vol 233 (1195) ◽  
pp. 480-493 ◽  
Keyword(s):  
Electrical Resistance ◽  
Low Temperatures ◽  
Free Electrons ◽  
Burgers Vector ◽  
Conduction Electrons ◽  
Wide Range ◽  
Electrical Conductivities ◽  
Lattice Waves ◽  
Silver Palladium ◽  
Palladium Content

Measurements have been made from 2 to 300° K of the thermal and electrical conductivities of a wide range of silver-palladium and silver-cadmium alloys. The thermal conductivity is resolved into its electronic and lattice components. It is shown that in annealed alloys below 10°K the lattice waves are scattered mainly by free electrons, that the conduction electrons interact with waves of all polarizations, and that this scattering is particularly strong for alloys of high palladium content, where one expects holes in the d -band. Above 40 % palladium , s - d scattering increases the electrical resistance and serious departures from Matthiessen’s rule are observed. The lattice conductivity of strained specimens is much lower, and the additional thermal resistance varies as T -2 , as does the resistance due to interactions with conduction electrons. It is suggested that the additional scattering is due to dislocations of large Burgers vector.

scholarly journals Optimisation of AWJM Process Parameters for Machining Granite using PCA Methodology

2019 ◽  
Vol 9 (2S2) ◽  
pp. 530-534
Keyword(s):  
Principal Component Analysis ◽  
Process Parameters ◽  
Removal Rate ◽  
Principal Component ◽  
Component Analysis ◽  
Standoff Distance ◽  
Work Piece ◽  
Machining Parameters ◽  
Cut Quality ◽  
The Impact

In Abrasive water jet machining, abrasive particles along with high pressure water are used to intrude on the work materials ranges from soft to hard materials using high velocity jet. The process parameters considered in this research for machining the granite are pressure, standoff-distance and cut quality. Experimental investigation had been carried out, in order to identify the impact of varying the input machining parameters on the results like kerf angle, material removal rate and roughness of the machined surface. In this study, Taguchi’s Multi response technique namely principal component analysis had been used to optimize the input parameters of the abrasive jet machine to obtain the desired outcome on granite work piece and also to foresee the best optimal input machining values of abrasive jet machining such as pressure, standoff-distance and cut quality. For each sequence of Taguchi L9 orthogonal array, sufficient number of experimentations had been carried out. Then with the help of principal component analysis, optimal process parameters that influence the granite machining characteristics have identified and to validate the experimentation, confirmation tests also been carried out with required combinations of array.

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