The Cost of Diversity in Textile Finishing

The effect on specific operating and capital costs of textile finishing, incurred by catering for the demands of a wide range of customers in varied styles, is illustrated. The return on investment in a new factory planned to operate under these conditions is realistically examined and a view expressed on the likely pattern of future investment in textile finishing.     

Electrical isolation design rule for GaAs integrated circuitsfabricated on semi-insulating substrates

The characteristics of n-semi-insulating-n (n-si-n) structures that dictate the design rules for electrical isolation between active devices of GaAs integrated circuits fabricated on semi-insulating substrates are studied by one-dimensional and two-dimensional numerical simulations. It is found that the I-V characteristics of these structures are characterized by sharp current-rising regions which result from a potential barrier lowering effect caused by the punchthrough phenomenon. Simplified expressions are derived for quick evaluation of the punchthrough voltages for both one-dimensional and two-dimensional analyses. For a given operating voltage, the one-dimensional calculation gives a larger spacing between n regions in a n-si-n structure for onset of large current flow than does the two-dimensional analysis. Therefore, the spacing obtained from one-dimensional results can be used as a conservative design criterion for device isolation. For more aggressive electrical isolation design, two-dimensional simulation is necessary since it provides more accurate results     

Effects of contact metals on minority carrier diffusion lengths in GaAs

Contact technology for GaAs involves optimizing such factors as contact resistance or Schottky barrier height, alloy cycle conditions, thermal ageing, adhesion, and ease of high resolution processing. Minority carrier properties may be significantly degraded by in-diffusing contact metals. At typical alloying conditions of 10 sec at 500° C, Ni diffuses at least 10 μm and reduces the hole diffusion length (L_p) in vapor phase epitaxial GaAs from 4.4 to 1.7 ym. At 600°C, L_p becomes 1.0 μm. Other metals, such as Fe, Pt, and Cr, significantly improve L_p in VPE GaAs. L_p increases from 3.0 to 5.0 μm for an Fe diffusion of 5 minutes at 500°C. These improvements may be due to interaction of in-diffused Fe with recombination centers, such as Ga vacancy complexes or Ni. Fe causes increases in minority carrier diffusion lengths also in n and p type ingot GaAs, though 800 – 900°C diffusions are required and at these temperatures the doping is significantly changed by Fe acceptors.     

Treatment process factors and satisfaction with drug abuse treatment.

Examined treatment satisfaction (TS) in relation to treatment outcomes (i.e., tenure and relapse for opioid use) and client and treatment variables in 532 methadone maintenance clients in a data system by M. Allison et al (1982). Satisfaction data were limited to the 1st 3 mo in treatment. Most Ss stated that the treatment had helped them to some degree with their drug problem or that they were at least somewhat satisfied with treatment. About three-quarters of the clients felt that the treatment had helped them at least somewhat with other nondrug problems. Overall, results suggested that TS measured early in treatment does not have strong direct effects on during-treatment-outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proximity printing of chrome masks

We have investigated the application of proximity printing to the copying of chrome masks used for integrated circuit fabrication. The mask blanks were coated with various positive and negative photoresists. When plotting the difference in width between etched lines on the print and the corresponding feature on the mask as a function of the separation, one observes fluctuations due to the movement of the diffraction peaks in the optical image. For the negative resist, the averaged difference in width is approximately constant to separations of 25 micrometer (μm), while for positive resists it changes monotonically with increasing gap spacing. The measured results are compared with calculations using a model of the resist exposure and development and good agreement is obtained. On the basis of these results we conclude that proximity printing would be difficult to apply to mask replication, but that it has considerable promise for replicating 10X step-and-repeat reticles.     

Turn-off-type field-controlled thyristor: Concepts for high power operation

The blocking state of a field-controlled thyristor (FCT) and the turn-off processes are discussed in relation to the design parameters of the structure. This leads to suggestions for a modified inner structure and a gate structure that should allow improved high power capability.Also considered is the integration of an FCT and a JFET to provide a device that is normally in the OFF state and that can be turned on and off by short low-power gate pulses.     

Optimization of multi-layer front-contact grid patterns for solar cells

In a front-contact grid pattern for a solar cell there is a trade-off necessary between shadowing loss and excessive power loss due to voltage drop in the metalization itself. If the metalization is too little there may be excessive contact resistance to the underlying semiconductor and insufficient coverage to control losses in the thin front-surface layer of the solar cell. Optimization of grid pattern area and geometry is considered analytically to minimize total losses.Worthwhile performance advantages are shown to be possible, particularly in concentrator systems, if multi-layer grid patterns are used. The current carrying fingers should be approximately square in metal cross section and the main current feedout bars should not only be wider but also thicker than the primary collecting fingers. This is termed multi-level metalization.Effective use of multi-level grid metalization allows much greater concentration-to-loss ratio for a cell of large area and permits good performance from cells of high front-layer sheet resistance.     

Comments on "The Paramorphic Representation of Clinical Judgment."

Hoffman's (see 34: 7779) position concerning the independent contribution of a variable in the judgment process is examined by presenting several empirical examples. It is concluded that the concept of relative weight will not provide any information about the independent contribution of a predictor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of rectangular waveguide-gratings for amplifierapplications

A slow-wave structure composed of a grating inside a rectangular waveguide is analyzed. This type of slow-wave structure is examined for use in a low-voltage amplifier application with a sheet electron beam. Dispersion curves, mode field profiles, and taper designs for the waveguide-grating are presented. The amplifier application places stringent requirements on the taper sections that match the smooth waveguide to the waveguide-grating with minimal reflection