We have studied the waiting time distributions (WTDs) for subgap transport through a singlelevel quantum dot tunnel coupled to one normal and one superconducting lead. The WTDs reveal the internal dynamics of the system, in particular, the coherent transfer of Cooper pairs between the dot and the superconductor. The WTDs exhibit oscillations that can be directly associated to the coherent oscillation between the empty and doubly occupied dot. The oscillation frequency is equal to the energy splitting between the Andreev bound states. These effects are more pronounced when the empty state and double-occupied state are in resonance.

Abstract-Phase-domainAnalog-to-Digital Converters (Ph-ADCs) have been considered for power-efficient implementation of body-area network transceivers employing phase demodulation. Conventional implementations of the Ph-ADCs, which work based on a full-flash zero-crossing algorithm, use linear resistive/current combiners to determine the thermometer digital code of the signal phase. These architectures suffer from high-accuracy requirements, high-circuit complexity, and highpower consumption. Therefore, in this paper, a new IQ-assisted binary-search algorithm is proposed for implementing the Ph-ADC. The proposed Ph-ADC architecture avoids employing the power-hungry linear combiner. Moreover, for an N-bit Ph-ADC, the proposed algorithm requires only N+1 comparisons, whereas the conventional full-flash counterpart demands 2 N−1 comparisons. Based on the proposed architecture, two different 5-bit charge-redistribution Ph-ADCs are designed and one of them is fabricated in a standard 0.18-µm CMOS technology. The prototype achieves an ENOB of 4.85 bits at 1 MS/s, while dissipating 12.9 µW from a 1.2-V supply.Index Terms-Phase-domain analog-to-digital converter, IQ-assisted binary search, charge-redistribution Ph-ADC.

In this study, the volumetric heat source in electron beam welding (EBW) is modeled through finite element method taking advantage of ABAQUS software package. Since this welding method is being applied in plates with different thicknesses and also considering that residual stresses reduce the strength of these weldments, the effect of thickness in the distribution and magnitude of residual stresses after welding is studied. Regarding the vast application of Inconel 706 super-alloy in aerospace industries, this material was selected in the current research. In order to validate the finite element model, the obtained results were compared to those of other researchers in this area, and good agreement was observed. The simulation results revealed that increase in the plate thickness leads to increase in the residual stresses. In addition heat treatment in the base metal (before welding) increases the residual stresses significantly.

There is a great deal of interest in the use of nanostructured heterogeneous catalysts, particularly those based on expensive precious metals, in order to maximise the surface to volume ratio of the catalyst, potentially reducing the cost without sacrificing performance. When there is an abundance of reactants available, the effective reactivity will depend on the surface density of the catalytically active sites. However, under diffusion-limited conditions, catalytically active sites may compete for reactants, potentially leading to diminishing returns from the use of nanostructures. In this paper we apply a mathematical homogenization approach to investigate the effect of scale and patterning on the effective activity of catalytic sites on a heterogeneous catalyst operating under diffusion-limited conditions. We test these theoretical results numerically using Monte Carlo simulations, and show that in the continuum limit the theory works well. In particular, in the limit where the mean free path is much less than the scale of patterning of catalytically active sites, the effective rate constant is found to be equal to the area-weighted harmonic mean of the rate constants on the surface. However, as the length scale of the patterns becomes comparable to the mean free path length, the simulations show that the effective activity of the system can exceed the theoretical limit suggested by the continuum theory.