Tapered electrode

Fig. 5.1 Computational modeling results for a standard T-shaped microfluidic fuei ceU with tapered electrodes on top and bottom surfaces, showing (a) the tapered electrode geometry and (b, c) fuel concentration contours in the center plane with vertical projections in (c). Reproduced with permission from Bazylak et al. [1]. Copyright Elsevier (2005)...

Fig. 4. Illustration of the use of a double-tapered connecting pin to join electrodes.

In a crystal-pulling procedure using a tri-arc furnace (Fig. 2), a resistor box, a d.c. power supply (300 A, 80/40 V) and a set of water-cooled power cables are used to bring power and water to the electrodes. The upper part of the furnace is equipped with three equally spaced copper cathodes, to which are fixed W-Rh electrodes. The upper part (cathode) is separated from the lower part (anode) by a transparent quartz glass tube. In the bottom of the furnace there is a tapered opening for a water-cooled copper hearth containing the boride melt. All parts of the furnace are also water... 

Early investigators assumed that this so-called diffusion layer was stagnant (Nernst-Whitman model), and that the concentration profile of the reacting ion was linear, with the film thickness <5N chosen to give the actual concentration gradient at the electrode. In reality, however, the thin diffusion layer is not stagnant, and the fictitious t5N is always smaller than the real mass-transfer boundary-layer thickness (Fig. 2). However, since the actual concentration profile tapers off gradually to the bulk value of the concentration, the well-defined Nernst diffusion layer thickness has retained a certain convenience in practical calculations. 

Tubes are typically 20-30 mm long and 5-10 mm in diameter after the design of Massman. In the past, the tube may have been turned down at the centre to increase the temperature at that point, or the whole tube may have tapered towards the centre ( profiling ) to shape the tube to the optical beam and increase the free atom density at the centre. Modem tubes tend not to have either of these modifications made to them. The graphite tube is held in place between two electrodes, axially in line with the light source, as shown in Fig. 3.4. 

LC-6). Cells LC-1 and LC-2 have holdup volumes of 2.0 and 0.7 ml., respectively. In the case of LC-2 the platinum electrodes and mercury well side arms are part of a standard-taper joint assembly. Cells LC-3 and LC-4 have holdup volumes of 0.16 ml. and external copper electrode caps. Cells LC-3 and LC-4 were stacked so as to be able to shift scales during the demineralization and regeneration half cycles, but a more convenient design was achieved in the compound cells, LC-5 and LC-6, with effective holdup volumes between 0.25 and 0.55 ml. Figure 6 is a drawing of LC-4 and LC-5. By using several inputs into the recorder, a continuous record can be obtained over a wide concentration range. 

Fig. 6.1 Two-electrode assembly (A) platinum wire (B) mercury-filled glass tube (C) thermometer adapter, 10/18 standard taper joint, Teflon (D) platinum electrodes 25 mm x 30 mm. Reprinted with permission [20],...

An HgCdTe layer 2 is formed on a sapphire substrate 1. A resist layer 3 having windows is shaped on the HgCdTe layer and an etching treatment is carried out to form through holes 4 in the HgCdTe layer. At the same time two opposite side-walls are tapered. An indium layer is deposited and electrodes 5 are formed on the slanted side-walls and on the exposed regions of the sapphire substrate when the resist layer is removed. 

The cell consists of a commercially available four-necked, 500-mL, round-bottomed flask equipped with a 34/45 standard-taper joint electrode assembly (Note 1), a 24/40 standard-taper joint purge and vent assembly, a mercury pool cathode (Note 2), a cathode contact (Note 3), a magnetic stirring bar (Note 4), and thermometer (inserted in a 10/18 standard-taper joint neck). The two platinum anodes of the electrode assembly (Note 1) are positioned in a horizontal plane ca. 1 cm above (Note 4) the mercury (Cathode) surface. 

To a 500-mL, round-bottomed flask having a central 34/45 standard taper neck and two 24/40 standard taper necks are added 120 g (0.75 mol) of methyl hydrogen hexanedioate (Note 2), 250 mL of methanol, 4.1 g (0.075 mol) of sodium methoxide, 10 mL of pyridine, and a magnetic stirring bar. The electrode assembly is inserted so that the platinum electrodes are immersed in the solution. A thermometer and reflux water condenser are attached. The mixture is heated to 60°C and stirred until the sodium methoxide dissolves. 

Most resistance moisture meters are essentially megohmeters that measure the resistance between pairs of pin electrodes driven into the wood to various depths. Because the pin electrodes taper along their lengths, the relationship between a resistance reading and the resistivity (resistance of a unit cube) is complex. Therefore the meters are calibrated empirically by using data obtained on a given species at room temperature (JO, 11),... 

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