This paper introduces a new powerful evolutionary algorithm called backtracking search algorithm (BSA) for solving load frequency control (LFC) problem in power system. Initially, two-area non-reheat thermal power plant is considered and gains of PI/PID controllers are optimized using BSA. This paper compares BSA’s effectiveness in solving LFC problem with the performances of other optimization techniques reported in the literature. Nonlinearities of power system such as reheater, governor dead band, boiler dynamics and generation rate constraint are included in the system modeling to identify the system stability and its performance is compared with craziness based PSO technique. Additionally, two more test systems namely three-area and four-area hydro-thermal plant with nonlinearity are considered to demonstrate the efficiency of proposed algorithm. The comparative analysis of the performances indicates that the proposed controller gives better results than other techniques available in the literature. Sensitivity analysis showed robustness of proposed controller under loading and parameter uncertainty.
The integration of distributed generation (DG) in distribution network may significantly affect its performance. Transmission networks are no longer accountable solely for voltage security issues in distribution networks with penetration of DGs. The reactive power support from the DG sources greatly varies with the type of DG units and may potentially distress the larger portion of the network from the voltage stability aspects. This paper presents the analysis for the selection of the best type of DG unit among different categories and its optimal location that can enhance the voltage stability of distribution network with simultaneous improvement in voltage profile. Voltage sensitivity index and bus participation factors derived from continuation power flow and Modal Analysis, respectively, are used together for voltage stability assessment and placement of DGs. Changes in mode shapes and participation factors with the placement of DGs are comprehensively analyzed for 33 and 136 nodes radial distribution network.
In this study, the entropy generation of micropolar fluid flow through concentric cylindrical annulus associated with slip and convective boundary conditions is performed numerically. The fluid flow in an annulus is due to the rotation of the outer cylinder with constant velocity. The analysis of such kind of fluid flow is governed by nonlinear partial differential equations. In the present study these equations are solved using the spectral quasilinearization method. The resultant velocity, microrotation and temperature distributions from the spectral quasi linearization method are used to evaluate the entropy generation rate and the Bejan number. Further the impact of boundary conditions on the entropy generation is also presented.
Contributors:Martin Leitner, David Simunek, Syed Faheem Shah, Michael Stoschka
Post-treatment methods enhance the fatigue strength of welded high-strength steel joints significantly. In industrial applications, one commonly applied technique is the high frequency mechanical impact (HFMI) treatment. Attained local benefits increasing fatigue strength are the compressive residual stress state, the reduced notch effect at the weld toe, and additionally the local work hardening of the material. This paper presents the set-up of a closed simulation loop including structural weld simulation, numerical computation of the HFMI-process, and a numerical evaluation of the local fatigue life.
This paper addresses an optimal model reference adaptive system (MRAS) to design power system stabilizer (PSS) in multi-machine electric power systems. Weighting factors of the proposed MRAS are adjusted by particle swarm optimization (PSO) as well as its input signal is limited by a normalization technique to assure network stability. The proposed modified-optimal MRAS-PSS is evaluated against conventional PSS to demonstrate its advantages. In order to investigate the performance of the proposed MRAS-PSS under parametric uncertainties, three operating conditions are defined and simulated. Several nonlinear and time-domain simulations are carried out to validate the viability and effectiveness of the proposed MRAS-PSS under network uncertainties.
Developing strategies for the water sector in integrated manner is essential. The present study details the development and uses of the Water Poverty Index (WPI) to be applied as a holistic tool for the conceptualization of water strategies in Egypt. The WPI herein considers the following: (i) water availability; (ii) access to water taking into account energy as a factor to water system operation; (iii) capacity to manage the water system considering the gender perspective; (iv) allocation of water uses considering the economic value of water; and (v) quality of the environment. The developed WPI was applied at the Egyptian governorates level and priorities to be achieved in their water sector were determined. The study concluded that, WPI as a summarized index combines into a single number a cluster of data is considered a robust tool to assist decision makers in determining priority to conduct prospect development plans in the water sector.
Contributors:L. Ramió-Torrentà, J.C. Álvarez-Cermeño, R. Arroyo, B. Casanova-Estruch, O. Fernández, J.A. García-Merino, M.A. Hernández, G. Izquierdo, S. Martínez-Yélamos, J. Meca, E. Moral, J. Olascoaga, J.M. Prieto, A. Saiz
La alteración de la marcha es frecuente en la esclerosis múltiple (EM) y tiene un gran impacto negativo en los pacientes pues conlleva a la pérdida progresiva de autonomía personal y social, y de productividad laboral. Esta guía pretende establecer recomendaciones para la evaluación del deterioro de la marcha y el uso de fampridina de liberación prolongada (fampridina-LP) como tratamiento de pacientes con EM y deterioro de la marcha en España.
Contributors:M.T. Sánchez Rodríguez, S. Collado Vázquez, P. Martín Casas, R. Cano de la Cuerda
La mHealth, definida como la prestación de información o asistencia sanitaria a través del uso de dispositivos móviles o tabletas, se postula como una de las grandes apuestas para pacientes, proveedores e inversores. Una app es un programa, con unas características especiales, que se instala en un dispositivo móvil, ya sea tableta digital o teléfono inteligente, y que suele tener un tamaño reducido, y cuyo objetivo es facilitar la consecución de una tarea determinada o asistir en gestiones diarias, siendo el modo de interacción entre el usuario y la aplicación el tacto.
Contributors:M. Kharrat, V. Placet, E. Ramasso, M.L. Boubakar
Pattern recognition of Acoustic Emission (AE) data is generally performed based on prior knowledge about the acoustic signatures of material damage mechanisms. Traditionally, these signatures are implicitly assumed to be unaffected by damage accumulation during the fatigue life of the material. This study investigates the influence of cumulated damage under cyclic loading on the acoustic signatures of local fracture mechanisms in composites. Artificial AE sources are created using an ultrasonic transmitter and a Pencil Lead Break in order to reproduce various real-like AEs, such that the waveforms, measured at the sensor level, are characterized as similar to real acoustic signatures of local fractures in carbon/epoxy composites. It is shown that these waveforms are distorted with damage accumulation in both time and frequency domains, leading to important changes in the AE-features used in data classification. Consequently, this can engender unreliable statistical representation of the AE sources in such non-stationary media.