Translinear circuits in subthreshold MOS

In this paper we provide an overview of translinear circuit design using MOS transistors operating in subthreshold region. We contrast the bipolar and MOS subthreshold characteristics and extend the translinear principle to the subthreshold MOS ohmic region through a drain/source current decomposition. A front/back-gate current decomposition is adopted; this facilitates the analysis of translinear loops, including multiple input floating gate MOS transistors. Circuit examples drawn from working systems designed and fabricated in standard digital CMOS oriented process are used as vehicles to illustrate key design considerations, systematic analysis procedures, and limitations imposed by the structure and physics of MOS transistors. Finally, we present the design of an analog VLSI translinear system with over 590,000 transistors in subthreshold CMOS. This performs phototransduction, amplification, edge enhancement and local gain control at the pixel level.     

Influence of plasmonic Au nanoparticles on the photoactivity of Fe₂O₃ electrodes for water splitting

An experimental study of the influence of gold nanoparticles on α-Fe(2)O(3) photoanodes for photoelectrochemical water splitting is described. A relative enhancement in the water splitting efficiency at photon frequencies corresponding to the plasmon resonance in gold was observed. This relative enhancement was observed only for electrode geometries with metal particles that were localized at the semiconductor-electrolyte interface, consistent with the observation that minority carrier transport to the electrolyte is the most significant impediment to achieving high efficiencies in this system.     

A three-parameter mechanical property reconstruction method for MR-based elastic property imaging

A reconstruction process featuring full parameterization of the three dimensional, time-harmonic equations of linear elasticity is developed and reconstructed property images are presented from simulation-based investigation. While interesting in its own right through the potential for increased adaptability of these reconstructive elastic imaging techniques, this study also presents a set of analysis tools used to study the poor convergence behavior found in the case of tissue like conditions (i.e. nearly incompressible materials). The choice of elastic properties for imaging in elastography research remains an open question at this point; the use of the stability and sensitivity-based analytical methods described here will help to predict and understand the value and reliability of different parameterizations of elasticity imaging. Additionally, though results indicate significant work needs to be done to achieve effective multiparameter reconstructive imaging, the methods detailed here offer the promise of increased flexibility and sophistication in elastographic imaging techniques.     

Decomposition Algorithms for Solving NP-hard Problems on a Quantum Annealer

NP-hard problems such as the maximum clique or minimum vertex cover problems, two of Karp’s 21 NP-hard problems, have several applications in computational chemistry, biochemistry and computer network security. Adiabatic quantum annealers can search for the optimum value of such NP-hard optimization problems, given the problem can be embedded on their hardware. However, this is often not possible due to certain limitations of the hardware connectivity structure of the annealer. This paper studies a general framework for a decomposition algorithm for NP-hard graph problems aiming to identify an optimal set of vertices. Our generic algorithm allows us to recursively divide an instance until the generated subproblems can be embedded on the quantum annealer hardware and subsequently solved. The framework is applied to the maximum clique and minimum vertex cover problems, and we propose several pruning and reduction techniques to speed up the recursive decomposition. The performance of both algorithms is assessed in a detailed simulation study.