Generalized Givens Rotations Applied to Complex Joint Eigenvalue Decomposition

This paper shows the different ways of using generalized Givens rotations in complex joint eigenvaluedecomposition (JEVD) problem. It presents the different schemes of generalized Givens rotation, justifies the introducedapproximations and focuses on the process of extending an algorithm developed for real JEVD to the complex JEVD.Several Joint Diagonalization problem use generalized Givens rotations to achieve the solution, many algorithmsdeveloped in the real case exist in the literature and are not generalized to the complex case. Hence, we show herein asimple and not trivial way to get the complex case from the real one. Simulation results are provided to highlight theeffectiveness and behaviour of the proposed techniques for different scenarios.

Challenges for Future Flexible Electric Power Systems

This paper describes some of the challenges that face the operation of future electric power systems. These systems are becoming more flexible and agile. Their physical structures and connections are continuously changing as microgrids, electric vehicles, and other generation and storage devices are connected/disconnected from the grid, which result in new challenges for the operation, management, and control of the systems of the future that incorporate active participation of the consumers, and high penetration of intermittent nature renewable resources such as wind and solar.

2-D Steady-State Heat Transfer Prediction in Rotating Electrical Machines Taking into account Materials Anisotropy: Thermal Resistances Network, Exact Analytical and Hybrid Methods

This paper presents two-dimensional (2-D) thermal resistances network (TRNM), exact analytical (AM) and hybrid (HM) methods for calculating steady-state temperature and heat flux distribution in rotating electrical machines considering materials anisotropy (i.e., different thermal conductivities in both directions). They are based on the thermal equivalent circuit (TEC), the improved exact subdomain (SD) technique where the solution and thermal conductivities depend on both directions (r, theta) and the coupling between the two methods. TRNM is known as a semi-analytical method that can predict the heat transfer in the machine in less time than finite element method (Fem). The implementation of TRNM by considering the difference between the thermalconductivities in (r, theta) using its equivalence with Fem is presented. The SD technique is improved to consider the difference between thermal conductivities in the directions (r, theta). It is known that the SD technique with non-homogeneous boundary conditions (BCs) is very sensitive to the dimensions of SDs where the harmonics number and the accuracy are lower in small subdomains. Hence, the HM from the TRNM and AM is given to answer these inaccuracies especially in electrical machines with a high number of stator slots and rotor poles. The heat sources are volumetric power losses due to hysteresis, eddy-current, Joule losses and windage losses in all the regions of the machine obtained by a simplified method. The studied problem is conductive with conductive interface conditions (ICs) and convective heat transfer between the machine and the external air and at the rotor internal air. The semi-analytical results are compared between them as well as with those obtained by Fem.

Transient impedance of grounding system with impulse superimposed sinewave

Investigating the transient performance of grounding systems subject to lightning (impulse or impulse superimposed sinewave) is valuable for protecting the power system and maintaining the system operation. In this work, the grounding system's impedance is computed when an impulse superimposed sinewave is applied to the grounding grid's proposed lumped circuit and grounding system can be simulated as an inductance in series with resistance, and all of them are in parallel with capacitance based on Thione's assumption. Several variables were investigated to study their effects on the grounding system's behavior. The variables were the soil resistivity, soil permittivity, main wire length, grid conductor radius, grid side length, grid configurationand its mesh number. The grounding system configuration varied between square and rectangular shapes, which connects to the protecting rod via the main wire conductor. A 3.69 kA peak of impulse current was applied to avoid soil ionization. The results indicated the performance of the grounding system when subjecting to impulse current.

Conditional and Unconditional Deterministic Bounds on the MSE of the Non-Uniform Linear Co-centered Orthogonal Loop and Dipole Array

The co-centered orthogonal loop and dipole (COLD) array exhibits some interesting properties, which makes it ubiquitous in the context of polarized source localization. In the literature, one can find a plethora of estimation schemes adapted to the COLD array. Nevertheless, their ultimate performance in terms the so-called threshold region of mean square error (MSE), have not been fully investigated. In order to fill this lack, we focus, in this paper, on conditional and unconditional bounds that are tighter than the well known Cramér-Rao Bound (CRB). More precisely, we give some closed form expressions of the McAulay-Hofstetter, the Hammersley-Chapman-Robbins, the McAulaySeidman bounds and the recent Todros-Tabrikian bound, for both the conditional and unconditional observation model. Finally, numerical examples are provided to corroborate the theoretical analysis and to reveal a number of insightful properties.

Surface EMG signal segmentation based on HMM modelling: Application on Parkinson’s disease

The study of burst electromyographic (EMG) activity periods during muscles contraction and relaxation is an important and challenging problem. It can find several applications like movement patterns analysis, human locomotion analysis and neuromuscular pathologies diagnosis such as Parkinson disease. This paper proposes a new frame work for detecting the onset (start) / offset (end) of burst EMG activity by segmenting the EMG signal in regions of muscle activity (AC) and non activity (NAC) using Discrete Wavelet Transform (DWT) for feature extraction and the Hidden Markov Models (HMM) for regions classification in AC and NAC classes. The objective of this work is to design an efficient segmentation system of EMG signals recorded from Parkinsonian group and control group (healthy). The results evaluated on ECOTECH project database using principally the Accuracy (Acc) and the error rate (Re) criterion show highest performance by using HMM models of 2 states associated with GMM of 3 Gaussians, combined with LWE (Log Wavelet decomposition based Energy) descriptor based on Coiflet wavelet mother with decomposition level of 4. A comparative study with state of the art methods shows the efficiency of our approach that reduces the mean error rate by a factor close to 2 for healthy subjects and close to 1.3 for Parkinsonian subjects.

Fullers Earth Treatment for Esters Liquids used in Power Apparatuses: Inferences and Arguments

Insulating Liquids are widely used for their electrical and thermal properties in power apparatuses, particularly at the level of liquid-filled transformers. With the shift in engineering aspects towards sustainable development, it is important to find a sustainable solution with ecofriendly nature. Therefore, alternative (biodegradable) liquids are of high importance in the global transformer communities. In the present study, the alternative dielectric fluids (ester-based) feasibility for potential regeneration with Fuller’s earth is investigated. The experimental results are confined to the reclamation temperature as well as the ratio of Fuller's earth (the sorbent) and the liquid. A suitable laboratory treatment apparatus is designed and is adopted in this study. Promising measurements to comment on the effectiveness of the treatment have been performed at controlled treatment temperature and sorbent-liquid ratio with the ASTM 7150-13 as a reference norm.The results of this study allowed 80°C and 1 g/30 ml as affirmative conditions for the present experimental conditions. Diagnostic measurements include turbidity, particle counter, and UV spectrophotometry before and after treatments. It is inferred that fuller’s earth is not a promising sorbent for the reclamation of ester liquids.

Non-conventional Band-notched UWB Antenna Design Based on Genetic Algorithm

In this paper, an improved applied approach based on Genetic Algorithm (GA) for antenna design is presented. It is basically useful to overcome electromagnetic interferences in UWB applications. First, an antenna in the range 2.8 - 20 GHz including UWB band was designed by using GA, then the undesired WiMAX band (3.5-3.8GHz) is rejected by optimizing appropriate Defected Ground Structure (DGS) filter. The proposed non-conventional filter consists of a matrix of rectangular cell shapes where each one is allocated by presence or absence of metal. The process is implemented in CST software using visual basic script. The method overcomes difficulties of conventional design. Furthermore, the optimized shape can be automatically obtained without appealing expert designers. Simulated and measured results demonstrate the effectiveness of the proposed design approach.

HPLC Method Development for the Fast Separation of a Complex Explosive Mixture

The growing threat of terrorism in many parts of the world has called for the urgent need to find rapid and reliable means of analyzing explosives. This is in view to help forensic scientists to identify different swabs from post-blast debris. The present study aims to achieve an efficient separation and identification of a mixture of sixteen explosive compounds (including nitroaromatics, nitramines, and nitrate esters) by high performance liquid chromatography using a diode array detection (HPLC/DAD) and an Agilent Poroshell 120 EC-120 C18 column at two wavelengths (235 and 214 nm). Relevant chromatographic parameters such as capacity factors, resolution, selectivity and number of theoretical plates have been optimized in order to achieve the best separation of the different components. In this respect, the effects of various parameters such as gradient time, column temperature, flow rate of mobile phase and initial percentage organic mobile phase on the separation of these compounds were investigated. It was revealed that the method allowed a fairly acceptable separation of all the compounds in less than 15 minutes except for two isomers, namely 4-A-2,6-DNT, 2-A-4,6-DNT and 2,6- DNT which could not be resolved by the used C18 column. This shortcoming notwithstanding, the developed method produced satisfactory results and demonstrated sensitive and robust separation, furthermore indicating that the HPLC developed method can be both fast and efficient for the analysis of complex mixtures of explosive compounds.

Vibration Signal Parameter Estimation in Variable Speed: Algorithms and performance bounds

Vibration signal parameter estimation for rotating machinery diagnostics operating under variable speedconditions is considered. At first, we provide a brief survey of existing methods for Quadratic Phase Signal (QPS)parameter estimation. Then, we introduce improved solutions for the general QPS case and the Order QPS (O-QPS)case, respectively. For all considered cases (namely the QPS, O-QPS with tachometer and O-QPS without tachometer),we develop the Cramer Rao Bounds to assess and compare the estimation performance limits for each model. Finally, wecompare the performance of all considered methods and highlight, in particular, the gain of the proposed solutions.