Multiple-input multiple-output least-squares constant modulus algorithms

Published versio

Perceptions of elementary teachers about physical activity breaks in the classroom

The purpose of this study was to explore classroom teachers’ perceptions in providing physical activity breaks during their regular lessons in their classrooms. Twenty-two randomly selected school teachers (6 men and 16 women) from public urban elementary schools participated in this study. Data collection took place in the participating school settings during regular school time and included 30-minute semi-structured interviews, teachers’ reflective journals and field notes taken for classroom facilities, number of students in each class, available space in each class, etc. Data were analyzed inductively by conducting a systematic search for similar patterns that occurred across the collected data. According to the results, teachers identified barriers to implementation of activity breaks, such as a) had a hard time for class management when movement activities were included, b) did not have a minimum repertoire of activities to implement in class, c) had limited pedagogical knowledge in implementing the activity breaks, d) had difficulties in re-starting the class, e) had a limitation of time, due to the additional workload, beyond their regular teaching load in class and other school responsibilities and f) had limited space to implement physical activity breaks in the classroom. As far as the content, results showed that teachers prefer activity breaks relevant to the lesson, enjoyable to students, or waking up students to attend the rest of the lesson effectively. These findings may have practical implications regarding physical education teacher education and professional development for classroom teachers

BlockVerify: Privacy-Preserving Zero-Knowledge Credentials Verification Framework on Ethereum

We present a general purpose, privacy-preserving framework for verifying user attributes. The framework is designed for users (e.g., a job candidate) to allow a challenger (e.g., a prospective employer) to verify whether the user meets a particular requirement (e.g., does the candidate hold a valid driving license?), without leaking any other information about the user. Importantly, the user is an active part of the challenge-verification process, which ensures that challenges cannot be made without the user's full knowledge and participation. The framework is decentralized and requires a public blockchain. A smart contract is used to manage the challenge-verification process, and zero-knowledge proofs are used to verify challenges in a privacy-preserving manner. We implement a simplified version of the framework using smart contracts deployed on the Ethereum blockchain, and we simulate some simple use cases. All simulation code is available open-source (https://github.com/lifeisbeer/BlockVerify)

Adaptive step-size blind multi-user detectors for DS-CDMA systems under deterministically and Markovian time-varying multipath environments

Published versio

Stochastic conjugate gradient based multi-user constant modulus algorithm for use in multiuser DS-CDMA environment

Published versio

The widely linear quaternion recursive total least squares

This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/ICASSP.2015.7178593A widely linear quaternion recursive total least squares (WLQRTLS) algorithm is introduced for the processing of Q- improper processes contaminated by noise. The total least squares for quaternions (QTLS) is a generalisation of the real-valued total least squares and is introduced rigorously, starting from the existence condition for low-rank approximation of quaternion matrices. Then, a quaternion Rayleigh quotient (QRQ) is defined to establish the link between the QTLS solution and the minimisation of the QRQ. Finally, the rank-one update formula is employed to allow for fast iterative solution based on the QRQ. Through simulations, the WL-QRTLS was shown to exhibit superior performance, under perturbations on both input and output signals, to other adaptive filtering of the same class - the widely linear quaternion least mean squares (WL-QLMS) and the widely linear quaternion recursive least squares (WL-QRLS). The experiments on both synthetic and real-world Q-improper processes supported the analysis