Effective resistance

Weld overlays of stainless steel or cobalt-based wear-resistant and hard-facing alloys such as Stellite may salvage damaged equipment. In addition, weld overlays incorporated into susceptible zones of new equipment may provide cost-effective resistance to cavitation damage. 

The phenomenon uneven distribution of current within the same conductor due to the inductive effect is known as the skin effect and results in an increased effective resistance of the conductor. The ratio of a.c. to d.c. resistance, R JR. is the measure of the skin effect and is known as the skin effect ratio . Figure 28.13(a) illustrates the skin elTect for various types and sizes of aluminium in flat sections. For easy reference, the skin effects in isolated round (solid or hollow) and channel conductors (in box form) are also shown in Figures 28.13(b) and (c) respectively. 

Since the skin effect results in an increase in the effective resistance of the busbar system it directly influences the heating and the voltage drop of the conductor and indirectly reduces its current-carrying capacity. If is the resistance as a result of this effect then the heat generated... 

If there is a rise of 5% in the effective resistance of the busbars due to the skin effect, then the a.c. rating will be... 

The displacement of current and the forces (equation (28.4)) on the conductors are two different effects. The effect of current displacement is to increase the effective resistance and the impedance of the conductor on one... 

The losses, and hence the effective resistance, are also increased by passing the line in close proximity to a nonmsulatmg surface—for example, passing the line over seawater. The metal from which the conductor is made is also vei y important—for example, copper has a lower resistance, for the same geometry, than aluminum does. Also related to the losses of the transmission Hue is the shunt resistance. Under most circumstances, these losses are negligible because the conductors are so well insulated however, the losses become much more significant as the insulators supporting the transmission line become contaminated, or as atmospheric and other conditions result in corona on the line. 

To avoid the errors of polarisation and stray currents, special resistivity meters are employed. One form of these uses an alternating current produced from batteries by a vibrator. The effective resistance is measured by a modified Wheatstone bridge with balance indicated by a galvanometer. 

The effective resistance of paint films may be influenced by ions derived from three sources ... 

A ceramic block such as alumina is generally used because of its chemical inertness and the orifice is bored or drilled to precise dimensions. The block is placed so that two (2) chambers result. Then if a DC voltage is applied across the electrodes, a current will flow onty through the orifice, and an effective resistance arises which depends upon the voltage applied and the size (volume of the conducting solution) of the orifice. Particles are added to one side of the two chambers created by the ceramic block, and the suspension is pumped through to the other side. There will be an electrical pulse as each particle passes through the orifice. 

In whole tissue or cell monolayer experiments, transcellular membrane resistance (Rm = Pm1) lumps mucosal to serosal compartment elements in series with aqueous resistance (R = P ). The operational definition of Lm depends on the experimental procedure for solute transport measurement (see Section VII), but its magnitude can be considered relatively constant within any given experimental system. Since the Kp range dwarfs the range of Dm, solute differences in partition coefficient dominate solute differences in transcellular membrane transport. The lumped precellular resistance and lumped membrane resistance add in series to define an effective resistance to solute transport ... 

A rotary filter which operates at a fixed vacuum gives a desired rate of filtration of a slurry when rotating at 0.033 Hz. By suitable treatment of the filter cloth with a filter aid, its effective resistance is halved and the required filtration rate is now achieved at a rotational speed of 0.0167 Hz (1 rpm). If, by further treatment, it is possible to reduce the effective cloth resistance to a quarter of the original value, what rotational speed is required If the filter is now operated again at its original speed of 0.033 Hz, by what factor will the filtration rate be increased ... 

When properly applied, ultraviolet detectors can serve as excellent fire detectors in munitions manufacturing. Detection times as fast as 10 milliseconds can be achieved while effectively resisting false alarms. 

The conductance of a solution is the inverse of its resistance, and conductance has units of ohms 1 or mohs. The higher the conductance of a solution, the lower is its electrical resistance. A conductivity meter and conductivity cell are used to determine the effective resistance of a solution. The conductivity cell consists of a pair of platinized platinum electrodes with an area of approximately 1.0 cm2 with spacers designed to hold the electrodes rigidly parallel and at a fixed distance from each other. The cell can be standardized with solutions of known conductivity to obtain the cell constant, k so that the instrument response R... 

The high resistance and mass provided by reinforced concrete structures makes it particularly suited for buildings located in close proximity to explosion sources. Concrete also provides effective resistance to fire and projectile penetration which are important considerations in many explosion accidents. 

This condition has been recently used in a vaporization-exchange model for water sorption and flux in phase-separated ionomer membranes. The model allows determining interfacial water exchange rates and water permeabilities from measurements involving membranes in contact with flowing gases. It affords a definition of an effective resistance to water flux through the membrane that is proportional to... 

L length of the pore (nm) m effective resistance to water flux Mp. molar mass of polymer (g mol i)... 

The development of resistance to pesticides by insects and herbicides by weeds poses a further ecological barrier for the industry. Industry analysts estimate that pests usually develop effective resistance to any new pesticide in less than ten years. This means new compounds must constantly be researched and run through the EPA registration process to replace those active ingredients that become useless, in addition to those that lose their patents or are banned by the FQPA. 

Electrochemical studies on a GC electrode and various metal oxide-based cathode surfaces confirm that the solution of LiPFe in mixed carbonates can effectively resist oxidation up to 5.1 thus... 

Permeability. The separators should not limit the electrical performance of the battery under normal conditions. Typically the presence of separator increases the effective resistivity of the electrolyte by a factor of 6—7. The ratio of the resistivity of the separator filled with electrolyte divided by the resistivity of the electrolyte alone is called MacMullin number. MacMullin numbers are as high as 10—12 have been used in consumer cells. 

Our studies indicate that rapid metabolic detoxification of linear furanocoumarins is an effective resistance mechanism for K polyxenes against the toxic effects of these compounds. It has been postulated that the adaptation of some plants to produce angular furanocoumarins was in response to the reduced effectiveness of the linear furanocoumarins as deterrents for herbivores such as polyxenes (22). Such may Indeed be true, but our studies on the comparative detoxification of linear and angular furanocoumarins suggest that, at best, the presence of angular furanocoumarins in plants confers only a tenuous margin of relative "safety" against polyxenes. 

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