Design considerations of recent advanced monolitic current-mode DC-DC converters

This paper is concerned with performance of the current shaping network in Average Current Mode (ACM) Active Power Factor Correction (APFC) systems. Theoretical expressions for the ripple components are derived. Then, ripple interaction and impact on the current loop reference signal are investigated. A modification of the controller network is suggested that results in an improved Total Harmonic Distortion (THD). Design guidelines are suggested. The theoretical predictions were validated by simulation.

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Morphological behavior of compatibilized ternary blends prepared by mechanical mixing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151830 ◽

1993 ◽

Vol 51 ◽

pp. 1200-1201

Author(s):

S.D. Smith ◽

R.J. Spontak ◽

D.H. Melik ◽

S.M. Buehler ◽

K.M. Kerr ◽

...

Keyword(s):

Interfacial Adhesion ◽

Diblock Copolymers ◽

Ternary Blends ◽

Mechanical Mixing ◽

Design Considerations ◽

Covalently Bonded ◽

Homopolymer Blends ◽

Emulsifying Agent ◽

Surface Active ◽

Low Entropy

When blended together, homopolymers A and B will normally macrophase-separate into relatively large (≫1 μm) A-rich and B-rich phases, between which exists poor interfacial adhesion, due to a low entropy of mixing. The size scale of phase separation in such a blend can be reduced, and the extent of interfacial A-B contact and entanglement enhanced, via addition of an emulsifying agent such as an AB diblock copolymer. Diblock copolymers consist of a long sequence of A monomers covalently bonded to a long sequence of B monomers. These materials are surface-active and decrease interfacial tension between immiscible phases much in the same way as do small-molecule surfactants. Previous studies have clearly demonstrated the utility of block copolymers in compatibilizing homopolymer blends and enhancing blend properties such as fracture toughness. It is now recognized that optimization of emulsified ternary blends relies upon design considerations such as sufficient block penetration into a macrophase (to avoid block slip) and prevention of a copolymer multilayer at the A-B interface (to avoid intralayer failure).

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Theoretical And Practical Design Considerations for Ultra-High Resolution Electron Lenses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001161 ◽

1980 ◽

Vol 38 ◽

pp. 266-269

Author(s):

Y. Harada ◽

K. Tsuno ◽

Y. Arai

Keyword(s):

Optical Properties ◽

High Resolution ◽

Chromatic Aberration ◽

Point Of View ◽

Pole Piece ◽

Axial Field ◽

Design Considerations ◽

Resolution Electron ◽

Practical Design ◽

Peak Flux

Magnetic objective lenses, from the point of view of pole piece geometry, can he roughly classified into two types, viz., symmetrical and asymmetrical. In the case of the former, the optical properties have been calculated by several authors1-3) and the results would appear to suggest that, in order to reduce the spherical and chromatic aberration coefficients, Cs and Cc, it is necessary to decrease the half-width value of the axial field distribution and to increase the peak flux density. The expressions for either minimum Cs or minimum Cc were presented in the form of ‘universal’ curves by Mulvey and Wallington4).

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