Nonlinear self-tuning control for power oscillation damping

Power systems exhibit nonlinear behavior especially during disturbances, necessitating the application of appropriate nonlinear control techniques. Lack of availability of accurate and updated models for the whole power system adds to the challenge. Conventional damping control design approaches consider a single operating condition of the system, which are obviously simple but tend to lack performance robustness. Objective of this research work is to design a measurement based self-tuning controller, which does not rely on accurate models and deals with nonlinearities in system response. Designed controller is required to ensure settling of inter-area oscillations within 10−12s, following disturbance such as a line outage. The neural network (NN) model is illustrated for the representation of nonlinear power systems. An optimization based algorithm, Levenberg-Marquardt (LM), for online estimation of power system dynamic behavior is proposed in batch mode to improve the model estimation. Careful study shows that the LM algorithm yields better closed loop performance, compared to conventional recursive least square (RLS) approach with the pole-shifting controller (PSC) in linear framework. Exploiting the capability of LM, a special form of neural network compatible with feedback linearization technique, is applied. Validation of the performance of proposed algorithm is done through the modeling and simulating heavy loading of transmission lines, when the nonlinearities are pronounced. Nonlinear NN model in the Feedback Linearization (FLNN) form gives better estimation than the autoregressive with an external input (ARX) form. The proposed identifier (FLNN with LM algorithm) is then tested on a 4−machine, 2−area power system in conjunction with the feedback linearization controller (FBLC) under varying operating conditions. This case study indicates that the developed closed loop strategy performs better than the linear NN with PSC. Extension of FLNN with FBLC structure in a multi-variable setup is also done. LM algorithm is successfully employed with the multi-input multi-output FLNN structure in a sliding window batch mode, and FBLC controller generates multiple control signals for FACTS. Case studies on a large scale 16−machine, 5−area power system are reported for different power flow scenarios, to prove the superiority of proposed schemes: both MIMO and MISO against a conventional model based controller. A coefficient vector for FBLC is derived, and utilized online at each time instant, to enhance the damping performance of controller, transforming into a time varying controller

Semiotics in Political Discourse. An Analytical Treatment of Political Text Criticisms Since 2003: The Case of the Discourse of Prime Minister Nouri Al-Maliki

This article discusses the function of semiotics in political discourse after the socio-political processes taking place in Iraq since 2003 and its role in the development of textual criticisms of some Iraqi politicians, analyzes the reasons for its functioning in the speech of politicians. The research is mainly focused on finding out to what extent political text studies draw on sign systems that can store and transmit information, the nature of its purpose and the use of available fields for the purpose to be achieved. The chief purpose of the study is to investigate and also clarify the symbols and signs appear within the framework of discursive Iraqi politicians, the nature of the symbols used, and the meanings that are included in the discourse in terms of structure, context, and form. Moreover, it has been attempted to define semiotic features in the texts of Iraqi politicians; and elicit structure, style and wording, and the degree of convergence of meaning and form in the semiotic application

Innovative Millimeter-Wave Components Based on Mixed Substrate Integrated Dielectric-Metallic Waveguides

RÉSUMÉ En recherche, un défi majeur pour l'onde millimétrique et les bandes Terahertz (THz) sont l'intégration des différents composants d'une manière compacte, efficace et à faible coût. La notion de circuits intégrés aux substrats (CIS) muni d'une variante de tradition pour une essentiel conception en simplifiant l'intégration du guide d'ondes rectangulaire (donc le GIS) avec d'autres lignes de transmission planaires telles que les lignes microbande et CPW. Bien que cette amélioré considérable conçue aux bandes de fréquences K et X, des limitations persistent dans des bandes plus élevées, en particulier la bande W. Nouvelles implémentations du concept de CIS en utilisant des guides d'ondes diélectriques, tels que le guide d’onde diélectrique non rayonnant (guide NRD), ont ainsi été proposées et avec un certain nombre de circuits à base de guide d’onde diélectrique non rayonnant intégrés aux substrats (SINRD) ont été conçus à des fréquences W-bande. Néanmoins, les critères de conception des guides rigides SINRD sont limités par leurs utilisations pratiques. Dans cette thèse, une version modifiée du guide SINRD, basée sur le guide image NRD (iNRD), est proposé. Ce travail sera le premier à étudier la faisabilité de la conception du guide iNRD avec le concept du CIS. La polyvalence du guide image SINRD résultant (iSINRD) sera démontrée par la conception d'un certain nombre de composants passifs qui fonctionnent à la fréquence centrale 94 GHz à la bande W. Plus précisément, les contributions suivantes ont été étudiées aux deux fréquences 88 GHz et 94 GHz:1.Une méthodologie de conception pour l’optimisation des circuits du classe NRD. À date, Cette méthode est l’alternative le plus simple et la méthode la plus informative.2.Un certain nombre de lignes de transmission pour guidage iSINRD qui sont conçus avec des différents profils de perforation et avec un nombre différent de lacunes sur la paroi métallique de l’image vertical.3.Des Guides iSINRD à angles aigus à large bande et à bande étroite.----------ABSTRACT A major challenge facing the millimetre-wave and terahertz (THz) research fields, is the integration of different components in a compact, efficient and low-cost fashion. The concept of substrate integrated circuits (SICs) provides a vital alternative to traditional design by simplifying the integration of the rectangular waveguide (thus the SIW) with other planar transmission lines such as microstrip and CPW lines. While this has substantially enhanced the design techniques at the X- and K-band frequencies, limitations still persist at higher bands, especially the W-band and beyond. New implementations of the SICs concept using dielectric waveguides such as the substrate integrated non-radiative dielectric (SINRD) guide, were thus proposed and a number of SINRD-based circuits were designed at the W-band frequencies. Nonetheless, the SINRD guide has rigid design criteria that limit its practical use. In this thesis, a modified version of the SINRD guide, based on the image NRD (iNRD) guide, is investigated. This work will be the first to investigate the feasibility of designing the iNRD guide with the SICs concept. The versatility of the resulting image SINRD (iSINRD) guide will be demonstrated by designing a number of passive components that operate at the W-band centre frequency of 94 GHz.Specifically, the following contributions have been made at the W band frequencies of 88 GHz and 94 GHz: 1.An optimised design methodology of the NRD-class circuits. This method is a simpler alternative to earlier methods and is more informative.2.A number of iSINRD guide transmission lines that are designed with different perforation profiles and with a different number of gaps in the metal wall.3.Broadband and narrowband iSINRD guide sharp corners4. Two different configurations of iSINRD guide directional couplers that support dual mode (LSM10 and TE20 modes) and dual band operation (one band for 0-dB coupling while the other for 3-dB coupling). The band pertinent to the 0-dB coupling is exclusive for one of the configurations. Thus, a total of six directional couplers are presented

Geopolitical Risk and Tourism Stocks of Emerging Economies

A bulk of literature suggests that geopolitical events such as terrorist attacks dampen tourism demand. However, there is little research on whether this effect helps predict the return of the tourism equity sector. We provide country-level evidence on whether local and global geopolitical risk (GPR) predicts the first and second moments of tourism stocks in emerging economies. This objective was achieved by employing the non-parametric causality-in-quantiles (CiQ) model and a cross-quantilogram (CQ) test, which allowed us to uncover the predictive potential of GPR for the tourism sector equities. Our findings, obtained through the CiQ model, suggest that while both local and global GPRs carry significant potential for predicting the returns and volatility of tourism stocks of most emerging economies under normal market conditions, they seem to play no such role in certain countries. These countries include South Korea, for which only a limited number of tourism stocks trade on the domestic stock market compared to other sectors, and Colombia, for which both the domestic stock market and tourism sectors are at an emerging stage. Further, it turns out that, compared to its local counterpart, global GPR has a more pronounced predictive power for the tourism stocks of emerging economies. Finally, with some exceptions, the results are qualitatively similar, and hence reasonably robust, to those when a directional predictability model is applied. Given that geopolitical shocks are largely unanticipated, our findings underscore the importance of a robust tourism sector that can help the market recover to stability as well as an open economy that allows local investors to diversify country-specific risks in their portfolios. Implications and directions for future research are discussed

Motion capture sensing techniques used in human upper limb motion: a review

Purpose Motion capture system (MoCap) has been used in measuring the human body segments in several applications including film special effects, health care, outer-space and under-water navigation systems, sea-water exploration pursuits, human machine interaction and learning software to help teachers of sign language. The purpose of this paper is to help the researchers to select specific MoCap system for various applications and the development of new algorithms related to upper limb motion. Design/methodology/approach This paper provides an overview of different sensors used in MoCap and techniques used for estimating human upper limb motion. Findings The existing MoCaps suffer from several issues depending on the type of MoCap used. These issues include drifting and placement of Inertial sensors, occlusion and jitters in Kinect, noise in electromyography signals and the requirement of a well-structured, calibrated environment and time-consuming task of placing markers in multiple camera systems. Originality/value This paper outlines the issues and challenges in MoCaps for measuring human upper limb motion and provides an overview on the techniques to overcome these issues and challenges

Spatiotemporal Analysis of Land Use / Land Cover in Swat, Pakistan Using Supervised Classification in Remote Sensing: 2000 to 2015

Changes in land use and land cover affect the social, economic and natural aspects of any area. Mostly land use and land cover (LULC) changes are the result of population growth and human activities in the form of urban agglomerations and industrialization etc. Physical factors like soil structure and type, slope condition, topography are main aspects. Land use change defines the historical pattern that how people used that specific land which depends on the availability of resources and economic conditions. LULC changes may trigger the detrimental effects like increase in natural hazard events and changes in climatic patterns. Climatic pattern directly affects the precipitation, groundwater recharge, the amount of evapotranspiration and runoff generation. On regional and local scale, LULC change is a far-reaching issue because environment and climate condition depend on i

Ameliorating drought effects in wheat using an exclusive or 2 co-applied rhizobacteria and ZnO nanoparticles

Simple Summary Wheat is a vital source of food, and its production is increasingly threatened by drought episodes. Moreover, its cultivation under water deficit situations along with zinc deficient soils is a major concern of declined wheat grain quantity and quality. Drought-linked changes in nutrient use efficiency, photosynthetic mechanisms, and chemical composition of wheat plants ultimately led to poorer harvest. Therefore, we aimed to understand the drought-ameliorating and grain nutritional improving effects in wheat by rhizobacteria (Azospirillum brasilense) and ZnO nanoparticles (NPs) under various growth stage-based drought stress episodes. Rhizobacteria colonized the host plant rhizosphere and provided growth promotion and stress amelioration. ZnO NPs were recognized as a potential water and zinc deficiency alleviator, and general growth promoter by triggering nitrogen metabolism, chlorophyll synthesis, membrane integrity, and grain zinc biofortification activities. Physio-biochemical observations indicated significantly higher positive effects under co-application over the sole use of either microbial or nanomaterials. Based on our research, it was concluded that co-applied Azospirillum brasilense and ZnO NPs generally increase wheat productivity under drought episodes with low operational cost to growers. Further, plausible synergistic physiological enhancement by NPs and rhizobacteria interaction may contribute towards sustainable wheat crop management under abiotic stresses. Drought is a major abiotic factor and affects cereal-based staple food production and reliability in developing countries such as Pakistan. To ensure a sustainable and consistent food supply, holistic production plans involving the integration of several drought mitigation approaches are required. Using a randomized complete block design strategy, we examined the drought-ameliorating characteristics of plant growth-promoting rhizobacteria (PGPR) and nanoparticles (NPs) exclusively or as a combined application (T-4) through three stages (D-1, D-2, and D-3) of wheat growth (T-1, control). Our field research revealed that Azospirillum brasilense alone (T-2) and zinc oxide NPs (T-3) improved wheat plant water relations, chlorophyll, proline, phenolics and grain quality, yield, and their allied traits over the stressed treatments. Specifically, the best outcome was observed in the combined treatment of PGPR and ZnO NPs (T-4). Interestingly, the combined treatment delivered effective drought mitigation through enhanced levels of antioxidants (15% APX, 27% POD, 35% CAT, 38% PPO and 44% SOD) over controls at the grain-filling stage (GFS, D-3 x T-1). The 40% improvements were recorded under the combined treatment at GFS over their respective controls. Their combined usage (PGPR and ZnO NPs) was concluded as an effective strategy for building wheat resilience under drought, especially in arid and semi-arid localities