scholarly journals XIV. On the specific resistance of mercury

1888 ◽  
Vol 179 ◽  
pp. 351-376 ◽  
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
Specific Resistance ◽  
Silver Wire ◽  
Tabular Form ◽  
Cavendish Laboratory

Of late years several determinations of the electrical resistance of mercury have been made, and the differences between the results arrived at have been greater than would be expected at first sight from the nature of the observations involved. The results of the experiments have been expressed either in terms of the ohm (10 9 absolute C. G. S. units) or of the B. A. unit, which, according to the determinations of Lord Rayleigh and one of the authors of this paper (R. T. G.), is equal to ·98667 ohm. In the case of Lord Rayleigh’s observations, a direct comparison was made between the mercury unit and the original B. A. standards. Other observers have constructed copies of their mercury resistances in German-silver wire, which have been compared with the B. A. standards at the Cavendish Laboratory by one of us, or have compared their tubes directly with copies in platinum-silver wire of the B. A. units which have been sent from Cambridge after careful testing. The result of these various comparisons of recent years is as follows, and may conveniently be put in tabular form, giving the value in B. A. units of the resistance of a column of mercury 1 metre long, 1 square millimetre in cross section, at 0° Centigrade.

scholarly journals Вплив параметрів адитивного формування на електричні властивості графітонаповненого композиту на основі полілактиду

2021 ◽  
Vol 150 (5) ◽  
pp. 93-102
Author(s):  
Н. В. Сова ◽  
О. О. Слепцов ◽  
Т. Р. Федорів ◽  
А. О. Мартиненко ◽  
М. Р. Кудлай ◽  
...  
Keyword(s):  
Electrical Properties ◽  
3D Printing ◽  
Electrical Resistance ◽  
Specific Resistance ◽  
Polymer Melt ◽  
Electrical Characteristics ◽  
Additive Production ◽  
Filled Composite ◽  
Printing Parameters ◽  
Bulk Electrical Resistance

Purpose. Investigate the effect of additive formation parameters on the properties of an antistatic composition based on polylactide (PLA). Methodology. Surface and bulk electrical resistance were determined by ASTM D257. Findings. The influence of additive formation parameters on the electrical properties of graphite-filled composite based on polylactide has been studied. It was found that the value of resistivity significantly depends on the printing conditions, namely the temperature, speed, thickness of the layer. Increasing the printing temperature helps to reduce the resistivity of the sample. Reducing the thickness of the polymer layer also reduces the resistivity at a print speed within 3000 mm / min It was found that the specific electrical characteristics are significantly different in the plane of the sample in contact with the printing platform. Concentric method of laying layers of polymer melt is less effective in terms of resistivity than mutually perpendicular. It was found that the electrical resistivity of samples made of material for 3D printing, which was previously subjected to drying below the resistance of the sample made of undried material. The programmed change of 3D printing parameters allows to control the specific resistance of graphite-filled composite based on polylactide in the range of three orders and to obtain products with properties from antistatic to statically dissipative materials. Additive production allows to obtain products of the desired configuration with adjustable electrical properties. Originality. The peculiarities of the change of antistatic properties of the polymer composite depending on the conditions of additive formation of experimental samples are investigated. Depending on the applied parameters of additive molding, it is possible to obtain products with properties from antistatic to statically dissipative materials. Practical value. Technological modes of additive molding of composite products based on polylactide and graphite have been developed. Energy consumption for additive formation of products of different mass is estimated.

Online Monitoring of Functional Electrical Properties in Aerosol Jet Printing Additive Manufacturing Process Using Shape-From-Shading Image Analysis

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Roozbeh (Ross) Salary ◽  
Jack P. Lombardi ◽  
Prahalad K. Rao ◽  
Mark D. Poliks
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
Online Monitoring ◽  
Shape From Shading ◽  
Sectional Area ◽  
Cross Sectional ◽  
Jet Printing ◽  
The Cross ◽  
Aerosol Jet Printing ◽  
Line Resistance

The goal of this research is online monitoring of functional electrical properties, e.g., resistance, of electronic devices made using aerosol jet printing (AJP) additive manufacturing (AM) process. In pursuit of this goal, the objective is to recover the cross-sectional profile of AJP-deposited electronic traces (called lines) through shape-from-shading (SfS) analysis of their online images. The aim is to use the SfS-derived cross-sectional profiles to predict the electrical resistance of the lines. An accurate characterization of the cross section is essential for monitoring the device resistance and other functional properties. For instance, as per Ohm’s law, the electrical resistance of a conductor is inversely proportional to its cross-sectional area (CSA). The central hypothesis is that the electrical resistance of an AJP-deposited line estimated online and in situ from its SfS-derived cross-sectional area is within 20% of its offline measurement. To test this hypothesis, silver nanoparticle lines were deposited using an Optomec AJ-300 printer at varying sheath gas flow rate (ShGFR) conditions. The four-point probes method, known as Kelvin sensing, was used to measure the resistance of the printed structures offline. Images of the lines were acquired online using a charge-coupled device (CCD) camera mounted coaxial to the deposition nozzle of the printer. To recover the cross-sectional profiles from the online images, three different SfS techniques were tested: Horn’s method, Pentland’s method, and Shah’s method. Optical profilometry was used to validate the SfS cross section estimates. Shah’s method was found to have the highest fidelity among the three SfS approaches tested. Line resistance was predicted as a function of ShGFR based on the SfS-estimates of line cross section using Shah’s method. The online SfS-derived line resistance was found to be within 20% of offline resistance measurements done using the Kelvin sensing technique.

scholarly journals VI. On the practical measurement of temperature: Experiments made at the Cavendish laboratory, Cambridge

1887 ◽  
Vol 178 ◽  
pp. 161-230 ◽  
Keyword(s):  
High Temperatures ◽  
Electrical Resistance ◽  
Platinum Wire ◽  
Cavendish Laboratory ◽  
Pure Platinum ◽  
Practical Measurement

In view of the enormous discrepancies at present existing in estimates of high temperatures, it is exceedingly desirable that strictly comparable thermometric standards should be issued by some recognised authority. Professor J. J. Thomson, in the course of a conversation which I had with him towards the close of 1885, suggested th at such standards could be issued in the form of platinum wire, the change of electrical resistance with temperature being determined by comparison for each specimen before issuing. The object of the present investigation was to test whether, in spite of the B. A. report on the Siemens pyrometer (1874), pure platinum wire might not be possessed of the necessary qualifications for such a standard.

scholarly journals Cross-section electrical resistance tomography of La Soufrière of Guadeloupe lava dome

2014 ◽  
Vol 197 (3) ◽  
pp. 1516-1526 ◽  
Author(s):  
Nolwenn Lesparre ◽  
Bartłomiej Grychtol ◽  
Dominique Gibert ◽  
Jean-Christophe Komorowski ◽  
Andy Adler
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
Lava Dome ◽  
Electrical Resistance Tomography

Preparation of Conductive Tungsten Carbide Layers for SiC High Temperature Applications

1999 ◽  
Vol 572 ◽  
Author(s):  
H. Romanus ◽  
V. Cimalla ◽  
S. I. Ahmed ◽  
J. A. Schaefer ◽  
G. Ecke ◽  
...  
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Tungsten Carbide ◽  
Electrical Resistance ◽  
Single Phase ◽  
Specific Resistance ◽  
Layer Structure ◽  
Carbide Formation ◽  
Pure Hydrogen ◽  
Dc Magnetron Sputtering

ABSTRACTThin tungsten carbide films of different compositions were prepared by DC magnetron sputtering of tungsten and carbon and subsequent annealing in different environments. The onset of carbide formation was around 800°C. Annealing in a pure hydrogen ambient generally results in carbon depletion in the layers with the formation of a dominant W2C phase. Adding propane enhances the carbon content in the layers and stimulates the formation of the WC phase. On silicon nitride substrates, variation of the propane concentration in an annealing environment allows a continuous alteration of the layer structure between polycrystalline single phase WC and a mixed layer with dominant W2C and with it, the adjustment of different values of the electrical resistance. In contrast, on thin (100)SiC layers a textured W2C phase was grown after annealing in propane/hydrogen at 900°C whereas at higher temperatures the formation of silicides was observed. In addition, the chemical composition and the temperature dependence of the electrical specific resistance were investigated and are also discussed.

scholarly journals Modeling the influence of thermal modification on the electrical conductivity of wood

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Christian Brischke ◽  
Kathrin A. Sachse ◽  
Christian R. Welzbacher
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Moisture Content ◽  
Electrical Resistance ◽  
Specific Resistance ◽  
Thermal Modification ◽  
Heat Treated ◽  
Wood Temperature ◽  
Color Data

Abstract A model has been developed aiming at the description of the effect of thermal modification on the electrical conductivity of wood. The intention was to calculate the moisture content (MC) of thermally modified timber (TMT) through the parameters electrical resistance R, wood temperature T, and CIE L*a*b* color data, which are known to correlate well with the intensity of a heat treatment. Samples of Norway spruce (Picea abies Karst.) and beech (Fagus sylvatica L.) samples were thermally modified in laboratory scale at 11 different heat treatment intensities and the resistance characteristics of the samples were determined. Within the hygroscopic range, a linear relationship between the resistance characteristics and the mass loss (ML) through the heat treatment was established. Based on this, a model was developed to calculate MC from R, T, and ML. To validate this model, color values of 15 different TMTs from industrial production were determined for estimation of their ML and fed into the model. MC of the 15 arbitrarily heat-treated TMTs was calculated with an accuracy of ±3.5% within the hygroscopic range. The material-specific resistance characteristics based on experimental data led to an accuracy of ±2.5%.

Concentration Fluctuation Spectra in Turbulent Slurry Pipeline Flow

1989 ◽  
Vol 111 (3) ◽  
pp. 317-323 ◽  
Author(s):  
R. J. Sumner ◽  
C. A. Shook ◽  
M. C. Roco
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
High Frequency ◽  
Particle Diameter ◽  
Low Frequency ◽  
Frequency Spectra ◽  
Concentration Time ◽  
Solids Concentration ◽  
Slurry Flows ◽  
Effective Domain

Using probes responding to changes of slurry electrical resistance with concentration, time spectra of longitudinal concentration fluctuations in turbulent slurry flows have been measured. The sensors, with an effective domain approximately 1 mm in diameter, showed the spectra to be relatively insensitive to location within the pipe cross section. High frequency spectra were found to be relatively insensitive to slurry concentration and particle diameter. Low frequency spectra showed fluctuation amplitudes which increased with solids concentration.

scholarly journals The scattering of slow neutrons by ortho - and para -hydrogen

1955 ◽  
Vol 230 (1180) ◽  
pp. 19-32 ◽  
Keyword(s):  
Scattering Amplitudes ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Amplitude ◽  
Coherent Scattering ◽  
Para Hydrogen ◽  
Cavendish Laboratory ◽  
Proton Interaction ◽  
Scattering Cross Sections ◽  
Slow Neutrons

The neutron velocity selector of the Cavendish Laboratory has been used to measure the scattering cross-sections of ortho- and para -hydrogen for slow neutrons. The triplet and singlet scattering amplitudes of the neutron-proton interaction may be deduced from these cross-sections. The values obtained are a t = (0·537 ± 0·004) x 10 -12 cm, a s = -(2·373 ±0·007) x 10 -12 cm, where a t and a s are the triplet and singlet scattering amplitudes respectively. The values of the coherent scattering amplitude ƒ = 2(3/4 a +1/4 a ), and of the free proton cross-section σ ƒ = 4π(3/4 a 2 t + 1/4 a 2 s given by the above values of a t and a s , are ƒ = -(0·380 ± 0·005) x 10 -12 cm, σ ƒ = (20·41 ± 0·14) x 10 -24 cm 2 .

scholarly journals Electrical resistivity tomography for aquifer imaging

2000 ◽  
Vol 22 ◽  
Author(s):  
Dipak Raj Pant
Keyword(s):  
Electrical Resistivity ◽  
Cross Section ◽  
Electrical Resistance ◽  
Apparent Resistivity ◽  
Electrical Resistivity Tomography ◽  
Field Experiments ◽  
Region Of Interest ◽  
Electrical Energy ◽  
Resistivity Tomography ◽  
Computerised Analysis

Aspects related to the development of a technique called electrical resistance tomography for producing two- or three­ dimensional subsurface images of an aquifer have been discussed. The technique is based on the automated measurement and computerised analysis of electrical resistivity changes caused by natural or man-made processes. A subsurface region of the aquifer to be studied is sampled by transmitting electrical energy through it along many paths of known orientations, and the apparent resistivity data derived are used to construct a cross-section al image of the region of interest. The physical model experiments and field experiments show that the presented method is effective and flexible for crosshole resistivity imaging of aquifer with bipole-bipole electrode configurations.

scholarly journals VIII. On the mechanical stretching of liquids: an experimental determination of the volume-extensibility of ethyl-alcohol

1892 ◽  
Vol 183 ◽  
pp. 355-370 ◽  
Keyword(s):  
Hydrostatic Pressure ◽  
Cross Section ◽  
Vapour Pressure ◽  
Cavendish Laboratory ◽  
Thin Glass ◽  
Mercury Column ◽  
State Of Tension ◽  
Mechanical Stretching ◽  
Inverted Barometer

Three methods are known by which a liquid may be subjected to a bodily tension. (1) The method of the inverted barometer , familiar to most physicists, by which, with care, a mercury column of many times the barometric height may be supported by its adhesion to the top of the tube. In such a column the hydrostatic pressure is negative above the barometric height, or the liquid above this level is in a state of tension. This tension increases with the height and is propagated in all directions to the walls of the tube. When the upper part of the tube is made elliptical in cross-section and of thin glass, its yielding to the inward pull may be easily observed. (2) The centrifugal method , devised by Professor Osborne Reynolds, in which a U-tube, ABCD, of glass, closed at both ends, contains air-free liquid, ABC, and vapour, CD. This tube is fixed to a suitable board and whirled about an axis, O, a little beyond the end, A, and perpendicular to the plane of the board. If CE (see figure) be the arc of a circle described about O, then while rotation continues the liquid between E and A is in a state of tension, increasing from zero (if we ignore the vapour-pressure) at E to a maximum at A. By this method Professor Osborne Reynolds has subjected water to a tension of about 5 atmospheres or 72·5 pounds per square inch, while the author, experimenting in the Cavendish Laboratory in 1886, succeeded in reaching, with alcohol, a tension of 7·9 atmospheres or 116 pounds per square inch, and, with strong sulphuric acid, 11·8 atmospheres or 173 pounds per square inch.

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