1. On the Electrical Conductivity of Stretched Silver Wires

1878 ◽  
Vol 9 ◽  
pp. 79-85 ◽  
Author(s):  
J. G. MacGregor
Keyword(s):  
Electrical Conductivity ◽  
Copper Wire ◽  
Silver Wire ◽  
The Other ◽  
Brass Plate

The apparatus which I used in a few experiments on silver wires was as follows:—To a beam, supported in stonework, a plate of copper was fastened, upon which a smaller plate could be tightly screwed. Between the two plates a very thick copper wire was secured, vertically. Its lower end was provided with a small plate of copper, fastened by screws. This plate served to make fast one end of the silver wire under investigation. The other end was joined in the same way to a second thick copper wire; this was provided with a horizontal round brass plate, through the centre of which it passed, and which acted as weight-carrier.

scholarly journals Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Qingzhong Mao ◽  
Yusheng Zhang ◽  
Yazhou Guo ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
High Speed ◽  
Copper Wire ◽  
Rapid Development ◽  
Dislocation Slip ◽  
Ultrafine Grains ◽  
The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

scholarly journals XXIII.—On the Disruptive Discharge of Electricity: An Experimental Thesis for the Degree of Doctor of Science, Department A

1878 ◽  
Vol 28 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Alexander Macfarlane
Keyword(s):  
Copper Wire ◽  
Late Summer ◽  
The Other ◽  
Straight Line ◽  
Summer Session ◽  
The Difference ◽  
A Chain ◽  
The One ◽  
Metallic Parts ◽  
The University

The experiments to which I shall refer were carried out in the physical laboratory of the University during the late summer session. I was ably assisted in conducting the experiments by three students of the laboratory,—Messrs H. A. Salvesen, G. M. Connor, and D. E. Stewart. The method which was used of measuring the difference of potential required to produce a disruptive discharge of electricity under given conditions, is that described in a paper communicated to the Royal Society of Edinburgh in 1876 in the names of Mr J. A. Paton, M. A., and myself, and was suggested to me by Professor Tait as a means of attacking the experimental problems mentioned below.The above sketch which I took of the apparatus in situ may facilitate tha description of the method. The receiver of an air-pump, having a rod capable of being moved air-tight up and down through the neck, was attached to one of the conductors of a Holtz machine in such a manner that the conductor of the machine and the rod formed one conducting system. Projecting from the bottom of the receiver was a short metallic rod, forming one conductor with the metallic parts of the air-pump, and by means of a chain with the uninsulated conductor of the Holtz machine. Brass balls and discs of various sizes were made to order, capable of being screwed on to the ends of the rods. On the table, and at a distance of about six feet from the receiver, was a stand supporting two insulated brass balls, the one fixed, the other having one degree of freedom, viz., of moving in a straight line in the plane of the table. The fixed insulated ball A was made one conductor with the insulated conductor of the Holtz and the rod of the receiver, by means of a copper wire insulated with gutta percha, having one end stuck firmly into a hole in the collar of the receiver, and having the other fitted in between the glass stem and the hollow in the ball, by which it fitted on to the stem tightly. A thin wire similarly fitted in between the ball B and its insulating stem connected the ball with the insulated half ring of a divided ring reflecting electrometer.

scholarly journals Emergence and biomass accumulation in seedlings of rice cultivars irrigated with saline water

2018 ◽  
Vol 22 (7) ◽  
pp. 471-475
Author(s):  
Márcio H. da C. Freire ◽  
Geocleber G. de Sousa ◽  
Maria V. P. de Souza ◽  
Emanuel D. R. de Ceita ◽  
Jamili N. Fiusa ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dry Matter ◽  
Saline Water ◽  
Biomass Accumulation ◽  
The Other ◽  
Saline Stress ◽  
Rice Cultivars ◽  
Saline Water Irrigation ◽  
Emergence Percentage ◽  
Mean Time

ABSTRACT The objective of this study was to evaluate the performance of three rice cultivars under saline water irrigation. The experiment was carried out in full sun at the Experimental Farm of the Unilab, in Redenção, Ceará, Brazil, in January 2016. The experimental design was completely randomized (CRD), in a 5 x 3 factorial scheme [irrigation water electrical conductivity (ECw: 0.5, 1.0, 2.0, 3.0 and 4.0 dS m-1) versus three rice cultivars (C1 - Ligeirinho, C2 - Casado and C3 - Meruinho)], totaling 15 treatments, with 4 replicates of 30 seeds per cultivar. After 21 days, the following variables were evaluated: emergence percentage (EP), emergence speed index (ESI), mean time of emergence (MTE), mean speed of emergence (MSE), shoot dry matter (SDM), root dry matter (RDM) and total dry matter (TDM). The cultivar Ligeirinho showed higher tolerance to saline stress with respect to the emergence percentage, emergence speed index and mean speed of emergence. The cultivar Casado showed higher tolerance to saline stress for shoot dry matter, root dry matter and total dry matter in comparison to the other cultivars.

scholarly journals A CONTRIBUTION TO THE HYDROCHEMISTRY AND WATER TYPOLOGY OF THE AMAZON RIVER AND ITS TRIBUTARIES

2019 ◽  
Vol 20 (72) ◽  
pp. 360-374 ◽  
Author(s):  
Maria do Socorro Rocha da Silva ◽  
Eduardo Antonio Ríos-Villamizar ◽  
Hillândia Brandão da Cunha ◽  
Sebastião Átila Fonseca Miranda ◽  
Sávio José Filgueiras Ferreira ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Physicochemical Properties ◽  
Amazon Basin ◽  
The Other ◽  
Amazon River ◽  
Left Bank ◽  
Guiana Shield ◽  
Ionic Charge ◽  
Physical Chemical ◽  
Geological Diversity

The geological diversity of the Amazon Basin, as well as the pluvial regime, influences the characteristics of the waters. To know the water types of the rivers of the Amazon basin, 288 superficial water samples were collected, 94 of them along the Amazon River and 194 in their tributaries, from March 2009 to September 2012. The physical, chemical, and physicochemical properties were analyzed. Rivers with pH between 6.5 and 7.6 and electrical conductivity (40.00 - 80.00 μS cm-1) are water bodies that are influenced by the Andean region (e.g., the Amazon River and some of its right bank tributaries). On the other hand, the rivers with pH in the range of 3.5 to 5.5 and conductivity <30.00 μS cm-1, which are Amazon River’s left bank tributaries, reflect the characteristics of the Guiana Shield. The rivers with pH (6.0 to 7.0), low ionic charge, and conductivity <40.0 μS cm-1, such as the lower Amazon River’s right bank tributaries (Tapajos and Xingu) which are influenced by the Central Brazilian Shield, and also the middle/upper Amazon River’s right bank tributaries (Tefé, Coari and Jutaí).

scholarly journals A.C conductivity and dielectric properties of (PVA/ PEO) blends doped with MWCNTs

2019 ◽  
Vol 14 (30) ◽  
pp. 64-72
Author(s):  
Ahmad A. Hasan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
The Other ◽  
Poly Vinyl Alcohol ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Maximum Value ◽  
Multi Walled Carbon Nanotube ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.

scholarly journals Structural and Electrical Properties of ZnO Varistor with Different Particle Size for Initial Oxides Materials

2019 ◽  
Vol 2 (2) ◽  
pp. 20-31 ◽  
Author(s):  
Susan A Amin
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Nonlinear Coefficient ◽  
Hexagonal Wurtzite Structure ◽  
The Other ◽  
Breakdown Field ◽  
Residual Voltage ◽  
Structural And Electrical Properties ◽  
Increasing Temperature ◽  
Initial Starting

We report here structural, electrical and dielectric properties of ZnO varistors prepared with two different particle sizes for initial starting oxides materials (5 µm and 200 nm). It is found that the particle size of ZnO does not influence the hexagonal wurtzite structure of ZnO, while the lattice parameters, crystalline diameter, grain size and Zn-O bond length are affected. The nonlinear coefficient, breakdown field and barrier height are decreased from 18.6, 1580 V/cm and 1.153 eV for ZnO micro to 410 V/cm, 7.26 and 0.692 eV for ZnO nano.  While, residual voltage and electrical conductivity of upturn region are increased from 2.08 and 2.38x10-5 (Ω.cm)-1 to 4.55 and 3.03x10-5 (Ω.cm)-1. The electrical conductivity increases by increasing temperature for both varistors, and it is higher for ZnO nano than that of ZnO micro.  The character of electrical conductivity against temperature is divided into three different regions over the temperature intervals as follows; (300 K ≤ T ≤ 420 K), (420 K ≤ T ≤ 580 K) and (580 K ≤ T ≤ 620 K), respectively. The activation energy is increased in the first region from 0.141 eV for ZnO micro to 0.183 eV for ZnO nano and it is kept nearly constant in the other two regions. On the other hand, the average conductivity deduced through dielectric measurements is increased from 2.54x10-7 (Ω.cm)-1 for ZnO micro to 49x10-7 (Ω.cm)-1. Similar behavior is obtained for the conductivities of grains and grain boundaries. The dielectric constant decreases as the frequency increases for both varistors, and it is higher for ZnO nano than that of ZnO micro. These results are discussed in terms of free excited energy and strength of link between grains of these varistors.

scholarly journals Adequacy of the Electrical Conductivity Test Methodology for Millet Seeds

2017 ◽  
Vol 9 (11) ◽  
pp. 130 ◽  
Author(s):  
Luanna Karoline Rinaldi ◽  
Diandra Javorski ◽  
Maicon Javorski ◽  
Ana Paula Mourão Simonetti ◽  
Tatiane Priscila Chiapetti ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Quality Control ◽  
The Other ◽  
Water Volume ◽  
Accelerated Ageing ◽  
Seed Imbibition ◽  
Test Methodology

Companies have sought to improve, more and more, the quality control of the seeds produced, improving tests that evaluate the vigor of the seeds with greater speed and precision. The objective of the present work was to study the effects of imbibition time on the results of the electrical conductivity test to evaluate the vigor of millet seeds and to correlate with the other tests carried out. Six seeds lots of the ADR300 cultivar with different vigor levels were used. Germination, first germination count, accelerated ageing, emergence and emergence speed of seedlings in sand and electrical conductivity with variations in water volume were performed (50 And 75 cm3), during the imbibition time of 2, 4, 6 and 8 hours, at 25 ºC. The time of 2 hours of the seed imbibition in 75 cm3 in water proved to be efficient to evaluate the vigor of millet seeds in all lots tested.

scholarly journals II. On the solvent power of liquid cyanogen

1872 ◽  
Vol 20 (130-138) ◽  
pp. 67-70 ◽  
Keyword(s):  
Copper Wire ◽  
The Other ◽  
Boiling Water ◽  
Small Fragment ◽  
Gutta Percha ◽  
Solvent Power

In the following experiments a number of stout tubes of refractory glass of the annexed shape were employed. Each tube was closed at one end, and had a flanged mouth at the other. The limb A was 11/2 inch long, the limb B 2 inches, and C 7 inches. In making the experiments, each tube was first filled, to an extent of 51/2 inches of its length, with highly dried crystals of mercuric cyanide; a small fragment of asbestus* was then pushed tightly against the end of the cyanide by means of a thin rod of gutta percha, and the bend of the tube cleaned by means of a slender brush. A number of taper plugs of gutta percha were previously made by softening, the end of a rod of that substance in boiling water and then chilling it ; and loops of thin copper wire were also prepared for the purpose of securing the plugs.

scholarly journals On the magnetic power of soft iron

1837 ◽  
Vol 3 ◽  
pp. 187-188
Keyword(s):  
Electric Current ◽  
Copper Wire ◽  
Complete Removal ◽  
The Other ◽  
Present Communication ◽  
Hard Steel ◽  
Electric Current Passing ◽  
Good Contact ◽  
The One ◽  
Single Helix

When free magnetism is developed by induction, and is not retained in that state by what has been termed the coercive force of hard steel, it has generally been considered that all the phenomena due to the existence of free magnetism cease on the removal of the inducing cause. The object of the present communication is to show that such is not the fact. From a variety of experiments described by the author, it appears that soft iron continued to exhibit strongly the attraction due to the developement of magnetism long after the means by which the magnetism had been originally excited had ceased to act. In these experiments, bars of soft iron, in the form of a horseshoe, had a single helix of copper wire wound round them, so that on the ends of the wire being brought into contact with the poles of a voltaic battery, the iron became an electromagnet. With one of these horse-shoes, while the connexion between the ends of the helix and the poles of the battery existed, the soft iron, having a keeper applied to its poles, supported 125 pounds it supported 56 pounds after that connexion had been broken, and continued to retain the power of supporting the same weight after an interval of several days, care having been taken not to disturb, during the time, the contact between the horse-shoe and its keeper. On this contact, however, being broken, nearly the whole attractive power appeared to be immediately lost. The author describes several instances of the same kind, particularly one in which the contact between the ends of the horse-shoe of soft iron and its keeper having been undisturbed during fifteen weeks, the attractive power continued undiminished. Although the interposition of a substance, such as mica or paper, between the ends of the horse-shoe and its keeper necessarily diminished the force of attraction, it did not appear to diminish the power of retaining that force. In a case where the electromagnet of soft iron and its keeper were equal semi-circles, the author found, what may appear singular, that the arrangement of the magnetism during the time that the electric current traversed the helix, appeared not to be the same as after the cessation of that current; in the one case similar, and in the other dissimilar, poles being opposed to each other at the opposite extremities of the two semi-circles. Whether the magnetism was originally developed in the soft iron by means of an electric current passing round it, or by passing over its surface the poles of an electromagnet, or those of a common magnet of hard steel, it appeared to possess the same power of retaining a large portion of the magnetism thus developed. The retention of the magnetism does not appear to depend upon the relative positions of the ends of the horse-shoe and the keeper remaining undisturbed, but on their contact remaining unbroken: for one keeper was substituted for another without diminution of this power; care being taken that the second should be in good contact with both ends of the horse-shoe before the complete removal of the first.

An English Romanesque Mount and Three Ninth-Century Strap-Ends

2003 ◽  
Vol 83 ◽  
pp. 433-441
Author(s):  
Richard Jewell
Keyword(s):  
Ninth Century ◽  
Silver Wire ◽  
The Other ◽  
Anglo Saxon ◽  
Early Medieval ◽  
Anglo Norman ◽  
Open Work

This note discusses several recent English finds of early medieval ornamental metalwork shown at the Society of Antiquaries on 16 May 2002: most notably, a Romanesque mount with open-work foliate decoration having clear parallels with Norman and Anglo-Norman ornament of c 1100–25. Four ninth-century Anglo-Saxon strapends are also described and illustrated, two of which have decorative features with links to contemporary larger-scale works but rarer within the corpus of strap-ends; the other two being unusual examples of East Anglian niello and silver-wire inlay.

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