Indirect materials

Semiconductors can be divided into two groups direct and indirect band gap materials. In direct semiconductors the minimum energy in the conduction band and the maximum in the valence band occur for the same value of the electron momentum. This is not the case in indirect materials. The difference has profound consequences for the transitions of electrons across the band gap in which light is emitted, the radiative transitions, of interest here. 

Bojnowski, J. J., Groghan, R. M., Jr., and Hoffman, R. M., Direct and Indirect Material Balance Control, Chemical Engineering Progress, September 1976. 

Scheme 3 Indirect material balance Scheme 4 Direct material balance...

Long time response (2) long time response and increasing complexity (3) V/F control is not desirable in general (4) column bottom level control by steam flow is desirable. (Comments are due toT. Umeda). b Direct M.B. = direct material balance control Indirect M.B. indirect material balance control V/F = vapor to feed ratio control... 

This zone folding effectively creates a direct gap SLS material from bulk materials which have indirect band gaps. As depicted in Figure 6, the absorption coefficients for these materials are enhanced over that for indirect materials. However, this absorption is less than that for direct gap materials due to the spatial separation of the electrons and holes within the SLS (5,20,28). 

Costs rise exponentially (rather than linearly) vs. quality. Therefore, do not goldplate items. Indirect materials are a fruitful area to investigate because they tend not to be antilyzed. For example, one firm compared the varnish applied on motor coils vs the varnish purchased there was a 10% difference. It was found that the varnish was bought in 55-gaUon drums. When the drums were being emptied, they were turned tight side up when there was still considerable product inside. The solution was a stand that permitted the varnish to drip out of the drum over a period of hours. 

Indirect materials are necessary to manufacture, test, and ship the product. Indirect materials are not part of the finished product. Sand used to build a sand-cast mold is an example of indirect material. There is a cost associated with indirect material, and in some situations the indirect material can be used over. 

Indirect labor, 2300 Indirect lighting, 1198 Indirect materials, 2300 Indirect measurement techniques (decision analysis), 2195... 

Optical detection methods have a suite of attractive features for many in situ monitoring and reaction optimization applications. These features include nondestructive measurement capabilities, fast response, low detection limit, means to analyze materials with no sample preparation, ease of multiplexing for parallel measurements of multiple compounds in the library, and spatial-mapping capabilities. One or several lightwave parameters (amplitude, wavelength, polarization, phase, and temporal property) can be measured and related to a material property of interest. Complementing direct measurements, in which the spectroscopic features of the material are measured, an indirect material determination can be used in which an auxiliary reagent is employed. ... 

Corbett C. J. and G. A. DeCroix. 2001. Shared-Savings Contracts for Indirect Materials in Supply Chains Channel Profits and Environmental Impacts. Management Science, Vol.47, 881-893. 

Adams MJ, Landsberg PT (1968) Laser light from indirect materials. In Proceedings of IX. International conference of the physics of semiconductors, Nauka, Moscow/Leningrad, pp 619-624... 

Table I. Theoretical expressions for the "oscillator strengths" of the LA, LO, TA, and TO phonon-assisted transitions in indirect materials. The subscript I refers to the phonon branch being considered. The spin orbit split band, is considered.

The tailoring of the supplier portfolio should also account for other characteristics of the product being sourced. A simple categorization of purchased goods is into direct and indirect materials. Direct materials are components used to make finished goods. For example, the processor is a direct material for a smartphone manufacturer. Indirect materials are goods used to support the operations of a firm. Office supplies are examples of indirect materials for an automotive manufacturer. Important differences between direct and indirect materials are shown in Table 15-8. 

Indirect materials and supplies (receiving, inspection, storage, handling, etc.)... 

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