Measured electrical resistance

An excellent review of experimental techniques for measuring electrical resistivity in aqueous solutions is available [34], Separators used in nonaqueous systems can be characterized by wetting them with a surfactant and measuring the electrical resistivity in an aqueous solution. Then the resistivity in a nonaqueous membrane can be estimated from Eq. (2). 

Electrical Resistivity Measurements. Electrical resistances were measured by the voltage-current method. The powder sample was compressed into a pellet with a diameter of V4 in. at 5000 psi. The pellet was placed Detween two brass electrodes, and the electrical resistance of the sample was determined from the measurements of the current through the sample and the potential across the sample. 

Diamond Hints, although not approaching bulk diamond, are harder than most refractory nitride and carbide thin films, which makes them attractive for tribological coatings. Transparency in the visible and infrared regions of the optical spectrum can be maintained and index-of-refraction values approaching that of bulk diamond have been measured. Electrical resistivities of diamond films have been produced within the full range of bulk diamond, and thermal conductivities equivalent to those of bulk diamond also have been achieved. As substrates for semiconductor electronic devices, diamond films can be produced by both the PACVD and IBRD techniques. 

The unit used to measure electrical resistance, that obstacle in the way of current flow, is the ohm. It represents resistance itself, along with its accompanying loss of energy, which are the barriers that superconductivity overcomes. 

Table 4 Measured electrical resistivity of a packed bed of carbonized oat hull charcoal ( 40 mesh) compressed at 846 kPa. 

The results have been reported of a comparative study of the measured electrical resistivities of liquid alkali metals and alloys, and the theoretical predictions for this quantity obtained within the diffraction model.48 The composition dependence of the Knight shifts in Na-Cs, Na-Rb, K-Rb-Cs, and Na-Rb-Cs liquid alloys has also been examined.49 Addition of small quantities of rubidium (0.3—4.51 atom %) to liquid sodium increases the electrical resistivity almost linearly with increasing solute concentration. With increasing temperature from 100 to 1100 °C, the effect of rubidium on the resistivity of sodium progressively diminishes.50 Addition of the solutes Hg, Tl, and Pb increases the resistivity of liquid potassium linearly with both increasing concentration and temperature. The unit increases in resistivity/pfl cm (atom%) , are 8.80, 9.85, and 15.8 for Hg, Tl, and Pb,... 

The salinity may be determined directly as a total content of water-soluble salts, or as a sum of contents of particular ions. The measurement of the specific electric resistance of the soil is a very rough, but simple and rapid method. It is used for soil surveys on a wide scale. For achieving more precise results, it is possible to use a method standardized by measuring the resistance in saturated soil paste (the soil paste is prepared by mixing a soil sample with distilled water to obtain a moderately liquefied paste) and the results are corrected with respect to a temperature of 16°C. Tables are used to convert the measured electrical resistance values to the soil concentration. For more precise data, it is possible to separate the solution from the saturated soil paste and to measure the specific electric conductivity. The solution separated from the soil paste is called the saturated soil extract. 

For metal or resin impregnated carbon.graphite materials, the extent of polymerization, cure cycles, and degradation can be assessed by measuring electrical resistance of the resin [lOlj. For example, the internal viscosity of a polymer can be determined by monitoring the electrical resistivity as a function of temperature. Electrical and electromagnetic properties of composites as well as NDT techniques are described next. 

Fuj] SEM, optical microscopy, TEM, electrical properties tests, Vickers hardness measurements Electrical resistivity and conductivity, hardness... 

A diagram of primary crystallization in the ternary system Cu-Fe-Pt was proposed for the first time by [1909Jae], but the earliest experimental studies were by [1941Nem] and [1943Nem2]. They used thermal analysis, optical microscopy hardness measurement, electrical resistivity and temperature coefficient determination. The thermoelectric power with respect to Pt, the extension and the tensile strength of the alloys were also determined. 

Nem, 1943Nem2] Hardness measurements, tensile and ductility measurement, electrical resistance, thermopower. Mechanical and electrical properties with respect to composition and temperature. 

The electrical resistances of the horizontal contacts between the plungers and the spacers as a function of temperature can be evaluated, by subtracting the experimentally measured electrical resistances of the F geometry from those of the SPP... 

Software, that automatically converts the measured electrical resistance into cell index (Cl) values by subtracting background electrical resistance (Yu et al., 2006). 

The maximum power of fuel cells H2/O2 and CH3OH/O2 with a membrane based on polymer complexes PBI/H3PO4 [7] was as high as 0.25 W cm at a current density of 700mAcm . The electrical resistance of electrolyte membranes was 0.4 the thickness and surface area of the membranes were 0.01 cm and 1 cm, and the doping level was 500 mol%. The measured electrical resistance of the cell was equivalent to a conductivity of 0.025 S cm It was found that the electrical resistance of the fuel cell is independent of the water content in the gas (water produced at the cathode is sufficient for maintaining the necessary conductivity of the electrolyte). This type of fuel cell was characterised by continuous operation at a current density of 200 mA cm over a period of 200 h (and for longer time periods) without reduction of the membrane performance. 

Classic techniques for measuring electrical resistivity of miCToporous separators have been described by Falk and Salkind and Robinson and Walker. The resistivity of an electrolyte is more accurately determined by AC methods since DC can polarize the electrodes and cause electrolysis of the solution. Modem AC impedance-measuring systems allow rapid measurements of cell resistance over a wide range or frequencies from which resistance can be calculated free of capacitance effects. Compared to the DC techniques, the equipment required and the theory... 

YOS] Unidirectional solidification measurements Electrical resistance Fe-l.72Si-3.91C and Fe-l.77Si-3.75C... 

Sai] Electrical resistivity measurements Electrical resistivity -196°C Fe-0.38S1-0.269C (at.%) (Fe-0.19Si-0.1251 C in mass%)... 

When a pressure is applied on the top conductive fabric, it will make contact with the bottom conductive fabric through the holes of the mesh and the measured electrical resistance will change. This fabric has been used to make products such as a fabric keyboard or an integrated textile keypad. 

Isotaphoresis is therefore an enrichment method in those cases where the original concentration of the analyte in the sample is lower than the concentration in the steady state. In isotaphoresis identification cannot be carried out on the time axis, because the parameter that is measured in time units corresponds to the length of the analyte zone passing the detector, and is dependent on the amount of the analyte. Identification is mainly carried out on the axis of the measured electrical resistance of the analyte zones, when the universal electrical conductivity (or potential gradient) detector is applied. In this way, the same analyte properties (the ionic mobilities) are as decisive for separation as they are for identification [29]. 

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