Nonbinary convolutional codes and modified M-FSK detectors for power-line communications channel

The Viterbi decoding algorithm, which provides maximum - likelihood decoding, is currently considered the most widely used technique for the decoding of codes having a state description, including the class of linear error-correcting convolutional codes. Two classes of nonbinary convolutional codes are presented. Distance preserving mapping convolutional codes and M-ary convolutional codes are designed, respectively, from the distancepreserving mappings technique and the implementation of the conventional convolutional codes in Galois fields of order higher than two. We also investigated the performance of these codes when combined with a multiple frequency-shift keying (M-FSK) modulation scheme to correct narrowband interference (NBI) in powerline communications channel. Themodification of certain detectors of the M-FSK demodulator to refine the selection and the detection at the decoder is also presented. M-FSK detectors used in our simulations are discussed, and their chosen values are justified. Interesting and promising obtained results have shown a very strong link between the designed codes and the selected detector for MFSK modulation. An important improvement in gain for certain values of the modified detectors was also observed. The paper also shows that the newly designed codes outperform the conventional convolutional codes in a NBI environment

Outcome-based module for continuous assessments in engineering education : case study department of electrical and electronic engineering science at the University of Johannesburg

Abstract: A big challenge for all engineering universities is the high quality of their graduated students to match the professional engineering qualities that industry need. In South Africa, the Engineering council of South Africa (ECSA) always asked for proof of evidence that students have demonstrated their capabilities to pass all the knowledge areas in each one of their modules in their engineering degree curriculum. The department of electrical and electronic engineering science at the University of Johannesburg has introduced a new continuous assessment framework based on outcomes in the offered modules. This framework allows for a deeper assessment of knowledge. Advantages and disadvantages of this new assessment scheme are discussed in this paper as well as the solutions proposed to make it a flexible and successful for all students

Course evaluation for low pass rate improvement in Engineering education

Abstract : A course evaluation is a process that includes evaluations of lecturers’ teaching performances and their course material moderations. These two procedures are usually implemented, whether officially by the faculty of engineering or by lecturers’ own initiatives, to help identify lecturers’ strengths and weaknesses and the ways forward to improve their performances and their qualities of teaching. This paper presents different ways of implementing these two criteria from students’ and professionals’ perspectives. Official questionnaires from the faculty of engineering, personal questionnaires using Google surveys, Moodle and special designed forms have been used for moderation and evaluations. The process of evaluation is the core of a feedback procedure followed by universities in order for them to monitor the teaching quality of their staff. Satisfactory results show that such a process can improve the lecturers’ teaching performances, courses material quality, students’ satisfaction and performances, and finally the pass rate of the class

Credit-based distributed real-time energy storage sharing management

Abstract: In this paper, energy storage sharing among a group of cooperative households with integrated renewable generations in a grid-connected microgrid is studied. In such a microgrid, a group of households, who are willing to cooperatively operate a shared energy storage via a central coordinator, aims to minimize their long term time-averaged costs, by jointly taking into account the operational constraints of the shared energy storage, the stochastic solar power generations and the time-varying load demands from all households, as well as the fluctuating electricity prices. This energy management problem, which comprises storage management and load control, is first formulated as a constrained stochastic programming problem. Based on the Lyapunov optimization theory, a distributed real-time sharing control algorithm is proposed to solve the constrained stochastic programming problem without requiring any statistical knowledge of the stochastic renewable energy generations and the uncertain power loads. The credit-based distributed sharing algorithm, in which each household independently solves a simple convex optimization problem without requiring any statistics of the system, is designed to quickly adapt to the system dynamics while facilitating a fair allocation of the shared energy storage with respect to individual households’ energy contributions. The performance gap of the proposed low-complexity distributed sharing algorithm is evaluated via theoretical analysis. Numerical simulations using a practical system setup are conducted to investigate the effectiveness of the proposed sharing control algorithm in terms of energy cost saving and fairness. The simulation results show that the proposed credit-based distributed sharing algorithm can not only save power consumption cost by coordinating the use the shared battery among households in a fair manner but also improve the utilization of renewable energy generation

Smart Energy Management for Smart Grids

This book is a contribution from the authors, to share solutions for a better and sustainable power grid. Renewable energy, smart grid security and smart energy management are the main topics discussed in this book

New distance concept and graph theory approach for certain coding techniques design and analysis

Abstract: A New graph distance concept introduced for certain coding techniques helped in their design and analysis as in the case of distance-preserving mappings and spectral shaping codes. A graph theoretic construction, mapping binary sequences to permutation sequences and inspired from the k-cube graph has reached the upper bound on the sum of the distances for certain values of the length of the permutation sequence. The new introduced distance concept in the k-cube graph helped better understanding and analyzing for the first time the concept of distance-reducing mappings. A combination of distance and the index-permutation graph concepts helped uncover and verify certain properties of spectral null codes, which were previously difficult to analyze

A distributed real-time control algorithm for energy storage sharing

Abstract: In this paper, energy storage sharing among a group of cooperative households with integrated renewable generations in a grid-connected microgrid in the presence of dynamic electricity pricing is studied. In such a microgrid, a group of households, who are willing to cooperatively operate a shared energy storage system (ESS) via a central coordinator, aims to minimize their long term time-averaged costs, by jointly taking into account the operational constraints of the shared energy storage, the stochastic solar energy generations and time-varying load requests from all households, as well as the fluctuating electricity prices. We formulate this energy management problem, which comprises storage management and load control, as a constrained stochastic programming problem. Based on the Lyapunov theory, a distributed real-time sharing control algorithm is proposed to provide a suboptimal solution for the constrained stochastic programming problem without requiring any system statistics. The proposed distributed real-time sharing control algorithm, in which each household independently solves a simple convex optimization problem in each time slot, can quickly adapt to the system dynamics. The performance of the proposed low-complexity sharing control algorithm is evaluated via both theoretical analysis and numerical simulations. By comparing with a greedy sharing algorithm and the distributed ESSs case, it is shown that the proposed distributed sharing control algorithm outperforms in terms of both cost saving and renewable energy generation utilization

Narrowband Signal Detection in OFDM Systems Using Spectral Shaping Techniques

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) allow data to be transmitted efficiently and reliably by using multiple orthogonal subcarriers. It provides robustness against noise and corruption in the channel. The channel can be either wired or wireless depending on the particular application. Due to the close spacing of subcarriers, OFDM is susceptible to corruption caused by various narrowband signals such as Narrowband Interference (NBI). Spectral shaping shapes the Power Spectral Density (PSD) in order to have certain properties. Spectral shaping might improve the effectiveness of OFDM and make it sustainable in the long run for applications beyond the 4th generation of mobile communications (4G) and Long Term Evolution (LTE). We make use of spectral null codes and load them onto OFDM subcarriers. Introducing narrowband signals in the channel degrades the system’s performance and also eliminates the designed spectral properties. From this observation we infer that some narrowband noise is present in the channel. Previously, carriers hit by NBI or other narrowband noise had to be switched off manually. We found that combining OFDM with spectral shaping allows the presence of Narrowband signals in the channel to be detected and conclusions can be drawn over the channel quality. This did not improve the system in terms of bit error rate performance

Security assessment of the smart grid : a review focusing on the NAN architecture

Abstract: This paper presents a comprehensive review on the security aspect of the smart grid communication network. The paper focus on the Neighborhood Area Network (NAN) cybersecurity and it laid emphasis on how the NAN architecture is such an attractive target to intruders and attackers. The paper aims at summarizing recent research efforts on some of the attacks and the various techniques employed in tackling them as they were discussed in recent literatures and research works. Furthermore, the paper presents a detailed review on the smart grid communication layers, wireless technology standards, networks and the security challenges the grid is currently facing. The work concludes by explaining current and future directions NAN communication security could consider in terms of data privacy measures. The data privacy measures are discussed in terms of prevention and detection techniques