Device requirements

Although its principal use is as a hardening agent for platinum, iridium is also used to make crucibles and devices requiring high temperatures. It is also used for electrical contacts. 

The birefringence of substrate materials for optical data storage devices requires special attention, especially in the case of EOD(MOR) disks. Birefringence has no importance for glass substrates (glass does not exhibit any significant birefringence) and is only a subordinate factor for polymeric protective layers of aluminum substrates because of their reflective read/write technique. 

The first semiconductor lasers, fabricated from gallium arsenide material, were formed from a simple junction (called a homojunction because the composition of the material was the same on each side of the junction) between the type and n-ty e materials. Those devices required high electrical current density, which produced damage ia the region of the junction so that the lasers were short-Hved. To reduce this problem, a heterojunction stmcture was developed. This junction is formed by growing a number of layers of different composition epitaxially. This is shown ia Figure 12. There are a number of layers of material having different composition is this ternary alloy system, which may be denoted Al Ga his notation, x is a composition... 

As for oil and gas, the burner is the principal device required to successfully fire pulverized coal. The two primary types of pulverized-coal burners are circular concentric and vertical jet-nozzle array burners. Circular concentric burners are the most modem and employ swid flow to promote mixing and to improve flame stabiUty. Circular burners can be single or dual register. The latter type was designed and developed for NO reduction. Either one of these burner types can be equipped to fire any combination of the three principal fuels, ie, coal, oil and gas. However, firing pulverized coal with oil in the same burner should be restricted to short emergency periods because of possible coke formation on the pulverized-coal element (71,72). 

Pressure-relief-device requirements are defined in Subsec. A. Set point and maximum pressure during relief are defined according to the service, the cause of overpressure, and the number of relief devices. Safety, safety relief, relief valves, rupture disk, breaking pin, and rules on tolerances for the reheving point are given. 

It is essential that persons be grounded in hazardous (classified) locations. For most (memical operations, the resistance to ground from the body should not exceed 100 megohms. A lower allowable resistance may be specified for locations where the presence of pri-maiy explosives, hydi ogen-air mixtures, oxygen-enriched mixtures, or certain solid-state devices requires faster charge dissipation. 

In the sampling train itself, the gas flow must be measured to determine the sample volume. Parhculates and gases are measured as micrograms per cubic meter. In either case, determination of the fraction requires that the gas volume be measured for the term in the denominator. Some sample trains contain built-in flow-indicahng devices such as orifice meters, roto-meters, or gas meters. These devices require calibration to assure that they read accurately at the time of the test and under test conditions. 

Gas turbines, like other mechanical devices, require inspection, maintenance, and service. Maintenance costs include the combustion system, hot-gas path, and major inspections. (See Chapter 21.) The effect of fuel type on maintenance costs is shown in Table 12-8. A cost factor is shown using natural gas as unity. The cost of maintenance is subject to great variations. Recognizing the great difficulty in establishing expected maintenance costs... 

Determine the size and location of relief devices required to protect an exchanger from overpressure during a tube rupture. 

Provide recall notices to recall devices requiring calibration. 

The modified FMEA approach has been used by the API to develop RP14C. In this document ten different process components have been analyzed and a Safety Analysis Table (SAT) has been developed for each component. A sample SAT for a pressure vessel is shown in Table 14-4. The fact that Tables 14-3 and 14-4 are not identical is due to both the subjective natures of a Hazard Analysis and FMEA, and to the fact that RP14C is a consensus standard. However, although the rationale differs somewhat, the devices required are identical. (The gas make-up system in Table 14-4 is not really required by RP14C, as we shall see.)... 

The SAT and SAC for each process component are updated periodically by API and the most recent edition should be used in any design. Plea.se note that for fired and exhaust heated components it may be necessary to include the devices required for a process tank or vessel as well as those required for the heating components. 

The science and technology of conducting polymers are inherently interdisciplinary they fall at the intersection of three established disciplines chemistry, physics and engineering hence the name for this volume. These macromolccular materials are synthesized by the methods of organic chemistry. Their electronic structure and electronic properties fall within the domain of condensed matter physics. Efficient processing of conjugated polymer materials into useful forms and the fabrication of electronic and opto-electronic devices require input from engineering i. e. materials science (more specifically, polymer science) and device physics. 

The Quality System Regulation is introduced for medical devices, requiring developers of high-risk devices to apply design controls. 

This is not a common approach, as new innovative devices will tend to be viewed as Class III devices requiring pre-market approval. However, if the manufacturer can show that the level of risk does not warrant placing it in the higher risk category, he/she may petition the FDA to have it reviewed through the de novo 510(k) procedure. 

However, many reactions of commercial interest have chemistry, mechanical, or system requirements that preclude the use of cross-flow reactors. Processes cannot use a cross-flow orientation primarily because of high temperatures and the need to internally recuperate heat such as steam methane reforming (SMR) [12, 13] and oxidation reactions [14]. Counter- and coflow devices require a micromanifold to dehver sufficiently uniform flow to each of the many parallel channels. 

To identify a certain pigment, monochromatic light is required, but the assessment of food quality by a human inspector or by a device requires normal daylight. The evaluation procedure, however, to be discussed in the next section, also involves decomposition into monochromatic (red, green, and blue) regions. Monochromatic dissection of a continuous spectrum by monochromators can be achieved in three ways ... 

Mapping of transport parameters in complex pore spaces is of interest for many respects. Apart from classical porous materials such as rock, brick, paper and tissue, one can think of objects used in microsystem technology. Recent developments such as lab-on-a-chip devices require detailed knowledge of transport properties. More detailed information can be found in new journals such as Lab on a Chip [1] and Microfluidics and Nanofluidics [2], for example, devoted especially to this subject. Electrokinetic effects in microscopic pore spaces are discussed in Ref. [3]. 

Class I General Devices require the lowest level of regulation. These devices are... 

Coupling an electrochemical cell to an analytical device requires that hindering technical problems be overcome. In the last years there has been a considerable improvement in the combined use of electrochemical and analytical methods. So, for instance, it is now possible to analyze on-line electrode products during the simultaneous application of different potential or current programs. A great variety of techniques are based on the use of UH V for which the emersion of the electrode from the electrolytic solution is necessary. Other methods allow the in situ analysis of the electrode surface i.e the electrode reaction may take place almost undisturbed during surface examination. In the present contribution we shall confine ourselves to the application of some of those methods which have been shown to be very valuable for the study of organic electrode reactions. 

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