Determining the optimal decision delay parameter for a linear equalizer

The achievable bit error rate of a linear equalizer is crucially determined by the choice of a decision delay parameter. This brief paper presents a simple method for the efficient determination of the optimal decision delay parameter that results in the best bit error rate performance for a linear equaliz

Large eddy simulation of a lifted ethylene flame using a dynamic nonequilibrium model for subfilter scalar variance and dissipation rate

Accurate prediction of nonpremixed turbulent combustion using large eddy simulation(LES) requires detailed modeling of the mixing between fuel and oxidizer at scales finer than the LES filter resolution. In conserved scalar combustion models, the small scale mixing process is quantified by two parameters, the subfilter scalar variance and the subfilter scalar dissipation rate. The most commonly used models for these quantities assume a local equilibrium exists between production and dissipation of variance. Such an assumption has limited validity in realistic, technically relevant flow configurations. However, nonequilibrium models for variance and dissipation rate typically contain a model coefficient whose optimal value is unknown a priori for a given simulation. Furthermore, conventional dynamic procedures are not useful for estimating the value of this coefficient. In this work, an alternative dynamic procedure based on the transport equation for subfilter scalar variance is presented, along with a robust conditional averaging approach for evaluation of themodel coefficient. This dynamic nonequilibrium modeling approach is used for simulation of a turbulent lifted ethylene flame, previously studied using DNS by Yoo et al. (Proc. Comb. Inst., 2011). The predictions of the new model are compared to those of a static nonequilibrium modeling approach using an assumed model coefficient, as well as those of the equilibrium modeling approach. The equilibrium models are found to systematically underpredict both subfilter scalar variance and dissipation rate. Use of the dynamic procedure is shown to increase the accuracy of the nonequilibrium modeling approach. However, numerical errors that arise as a consequence of grid-based implicit filtering appear to degrade the accuracy of all three modeling options. Thus, while these results confirm the usefulness of the new dynamic model, they also show that the quality of subfilter model predictions depends on several factors extrinsic to the formulation of the subfilter model itself

Analysis of turbulent flame propagation in equivalence ratio-stratified flow

Equivalence ratio-stratified combustion is an important technology for achieving stable low-emission operation in internal combustion engines and gas turbines. This study examines how equivalence ratio stratification affects the physics of turbulent flame propagation using Direct Numerical Simulation. Three-dimensional simulations of a turbulent slot-Bunsen flame configuration are performed with accurate multi-step kinetic modelling for methane-air combustion. We compare one perfectly-premixed and three equivalence ratio-stratified cases with the mean equivalence ratio gradient aligned with, tangential to or opposed to the mean flame brush. The simulation results are analysed in terms of flame surface area and the burning intensity. The local effects of stratification are then investigated further by examining statistics of the displacement speed conditioned on the flame-normal equivalence ratio gradient. The local burning intensity is found to depend on the orientation of the stratification with respect to the flame front, so that burning intensity is enhanced when the flame speed in the products is faster than in the reactants. This effect of alignment between equivalence ratio gradients and flame fronts has been observed previously in laminar flames and it is found here that it also affects the global behaviour of turbulent flames. The flame surface area is also influenced by equivalence ratio stratification and this may be explained by differences in the surface-averaged consumption speed and differential propagation effects due to flame speed variations associated with equivalence ratio fluctuations

Concurrent constant modulus algorithm and soft decision directed scheme for fractionally-spaced blind equalization

The paper proposes a concurrent constant modulus algorithm (CMA) and soft decision-directed (SDD) scheme for low-complexity blind equalization of high-order quadrature amplitude modulation channels. Simulation using a fractionally-spaced equalization setting is used to compare the proposed scheme with the recently introduced state-of-art concurrent CMA and decision-directed (DD) scheme. The proposed CMA+SDD blind equalizer is shown to have simpler computational complexity per weight update, faster convergence speed, and slightly improved steady-state equalization performance, compared with the CMA+DD blind equalizer

What does it mean for a data subject to make their personal data ‘manifestly public’? An analysis of GDPR Article 9(2)(e)

Key points This article investigates an under-discussed and potentially significant provision in the EU General Data Protection Regulation (GDPR), namely Article 9(2)(e), which permits processing of special category personal data if the ‘processing relates to personal data which are manifestly made public by the data subject’. This provision may be of increasing interest to data controllers in a variety of cloud-based, internet-related, and/or social media contexts. We specifically consider the application of this provision in the context of genetic data and open data sharing (ie data that can be freely used, re-used, and redistributed by anyone), illustrating this by way of several cases of initiatives that seek to share genetic data. We query whether by uploading one’s own genetic data onto the internet, a person has made their data ‘manifestly public’ within the meaning of the GDPR. Our response to this query is that in general, the answer should be no, but it remains possible. We argue that Article 9(2)(e) must be construed narrowly; outside of clearly defined contexts, it would be legally inappropriate to invoke and rely upon this manifestly public self-disclosure exception in data protection law. Our narrow interpretation of the provision aligns with the limited guidance made available from data protection authorities. As part of this argument, we propose a legal test that must be satisfied before Article 9(2)(e) may be lawfully invoked, and which is grounded in the intent of the data subject

The Topological Unitarity Identities in Chern-Simons Theories

Starting from the generating functional of the theory of relativistic spinors in 2+1 dimensions interacting through the pure Chern-Simons gauge field, the S-matrix is constructed and seen to be formally the same as that of spinor quantum electrodynamics in 2+1 dimensions with Feynman diagrams having external photon lines excluded, and with the propagator of the topological Chern-Simons photon substituted for the Maxwell photon propagator. It is shown that the absence of real topological photons in the complete set of vector states of the total Hilbert space leads in a given order of perturbation theory to topological unitarity identities that demand the vanishing of the gauge-invariant sum of the imaginary parts of Feynman diagrams with a given number of internal on-shell free topological photon lines. It is also shown, that these identities can be derived outside the framework of perturbation theory. The identities are verified explicitly for the scattering of a fermion-antifermion pair in one-loop order.Comment: 13 pages, LaTex file, one figure (not included

A ten-year comparison of women authorship in U.S. dermatology literature, 1999 vs. 2009

Women are entering medicine at increasing rates, particularly in dermatology. In this study, we compared women’s influence and status in academic dermatology with that of men by examining authorship roles in peer-reviewed dermatology literature.Weexamined the literature in2009 and compared that to10 years prior (1999).Atotal of 1399 articles were reviewed, 594 of whichmet study criteria andwere included in statistical analysis. There was amarked increase in senior female authorship over a decade (22% vs. 38%, p b 0.001). Female first authorship increased as well (41% vs. 51%, p b 0.001). In contrast, changes in male senior and first authorship were not statistically significant. Federal funding for female senior authors increased over a decade (19% vs. 37%, p=0.05), and female senior authors in the 2009 cohort were more likely to hold a dual MD/PhD degree (0% vs. 11%, p=0.04) or pure PhD degree (11% vs. 27%, p = 0.04).Women are approaching parity with men in terms of authorship in the dermatology literature, and additional research training and attainment of federal funding have helped women publish as senior authors

Dispersion of a single hole in the t-J model

The dispersion of a single hole in the t-J model obtained by the exact result of 32 sites and the results obtained by self-consistent Born approximation and the Green function Monte Carlo method can be simply derived by a mean-field theory with d-RVB and antiferromagnetic order parameters. In addition, it offers a simple explanation for the difference observed between those results. The presence of the extended van Hove region at (pi,0) is a consequence of the d-RVB pairing independenct of the antiferromagnetic order. Results including t' and t" are also presented and explained consistently in a similar way.Comment: LaTex file, 5 pages with 5 embedded eps figure