Design considerations for low-voltage on-board DC/DC modules fornext generations of data processing circuits

By reducing the power supply voltage, a higher speed, lower power consumption, and higher integration density of data processing ICs can be achieved. Presently, a variety of ICs operating from 3.3 V are available. Next generations of ICs are expected to work even with lower voltages, i.e., in the 1-3 V range, to further enhance their speed-power performance. At the same time, during transients, these new generations of data ICs will present very dynamic loads with high current slew rates. As a result, they will require point-of-load power supplies in order to minimize the effects of the interconnection parasitics. These onboard power supplies will be derived from the existing voltages available in the system (usually 5 or 12 V), and will be required to have high power densities, high efficiencies, and good transient performance. This paper presents design considerations for these on-board power supplies and discusses their performance limits imposed by various circuit and system parasitics     

Hybridized off-line 2-MHz zero-current-switched quasi-resonantconverter

Thick-film hybrid technology is used to develop a half-bridge, half-wave, zero-current-switched quasi-resonant converter for 300 V DC offline application. With a conversion frequency of 2 MHz the converter delivers 80 W at 78% efficiency with a power density, excluding heat sink, of 21 W/in³. The operation and detailed electrical and hybrid design of the circuit are described. Also described is a 2 MHz hybridized gate drive     

On the Coding Gain of Linear Binary Block Codes

The coding gain of linear binary block codes on the AWGN channel is studied. Antipodal signaling and hard decision demodulation are assumed. Simple asymptotic expressions for the gain at high and low energy to noise spectral density ratios are derived. Monotonicity of the coding gain is also discussed.     

Chaotic descent method and fractal conjecture

Very often, when dealing with computational methods in engineering analysis, the final state depends so sensitively on the system's precise initial conditions that the behaviour becomes unpredictable and cannot be distinguished from a random process. This outcome is rooted in an intricate phenomenon labelled ‘chaos’, which is a synonym for unpredictable events in nature. In contrast, chaos is a deterministic feature that can be utilized for problems of finding global solutions in both non‐linear systems of equations as well as optimization. The focus of this paper is an attempt to utilize computational instabilities in solving systems of non‐linear equations and optimization theory that resulted in development of a new method, chaotic descent. The method is based on descending to global minima via regions that are the source of computational chaos. Also, one very important conjecture is presented that in the future might lead the way towards direct solving of the systems of simultaneous non‐linear equations for all the solutions. Copyright © 2000 John Wiley & Sons, Ltd.     

Butyl Acrylate/Vinyl Acetate Emulsion‐Based Pressure‐Sensitive Adhesives: Empirical Modelling of Final Properties

The influence of the amounts of acrylic acid, chain transfer agent and anionic stabilizer on polymer microstructural properties and final adhesive performance of BA/VAc emulsion‐based PSAs on stainless‐steel and high‐density polyethylene substrates was investigated using a Box‐Behnken experimental design for 15 runs. The resulting data were empirically modelled. For each final adhesive property (i.e., loop tack, shear and peel strength), different models were found to fit the data. Similar models for loop tack and peel strength were found to be adequate for different PSA thicknesses on the same substrate. AA and SDS had significant effects on loop tack as did the AA‐SDS and CTA‐SDS two‐factor interactions. Quadratic peel strength models were found to adequately describe the data for SS substrate cases with a noticeable absence of any interaction parameters. The shear strength models were similar regardless of the substrate or thickness of the adhesive (e.g. in all models, AA and CTA, as well as their second‐order interactions, were the significant factors).     

Mapping the Chemical Space of Active-Site Targeted Covalent Ligands for Protein Tyrosine Phosphatases**

Protein tyrosine phosphatases (PTPs) are an important class of enzymes that modulate essential cellular processes through protein dephosphorylation and are dysregulated in various disease states. There is demand for new compounds that target the active sites of these enzymes, for use as chemical tools to dissect their biological roles or as leads for the development of new therapeutics. In this study, we explore an array of electrophiles and fragment scaffolds to investigate the required chemical parameters for covalent inhibition of tyrosine phosphatases. Our analysis juxtaposes the intrinsic electrophilicity of these compounds with their potency against several classical PTPs, revealing chemotypes that inhibit tyrosine phosphatases while minimizing excessive, potentially non-specific reactivity. We also assess sequence divergence at key residues in PTPs to explain their differential susceptibility to covalent inhibition. We anticipate that our study will inspire new strategies to develop covalent probes and inhibitors for tyrosine phosphatases.