1,027 research outputs found

    Design and assembly of a magneto-inertial wearable device for ecological behavioural analysis of infants

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    There are recent evidence which show how brain development is strictly linked to the action. Movements shape and are, in turn, shaped by cortical and sub-cortical areas. In particular spontaneous movements of newborn infants matter for developing the capability of generating voluntary skill movements. Therefore studying spontaneous infants’ movements can be useful to understand the main developmental milestones achieved by humans from birth onward. This work focuses on the design and development of a mechatronic wearable device for ecological movement analysis called WAMS (Wrist and Ankle Movement Sensor). The design and assembling of the device is presented, as well as the communication protocol and the synchronization with other marker-based optical movement analysis systems

    A Comparative Analysis of the Attitudes Toward Women Managers in China, Chile, and the United States

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    Purpose: The purpose of this paper is to determine if stereotypical perceptions of women as managers existed among men and women in three cultural settings: the U.S., China and Chile. Based on the extant literature, hypotheses were developed and tested. Design/Methodology Approach : Participants in our study were students enrolled in degree programs. The data was collected from the U.S., China and Chile. Using the women as mangers scale (WAMS), the study explores attitudinal dimensions. Further, gender and country effects were identified at both multivariate and univariate levels. Findings: The findings show that stereotypical perceptions of women as mangers exist among men and women in three cultural settings (the U.S., China and Chile). For instance, U.S. and Chilean men had more positive perceptions of women as managers than Chinese men. Further, Chinese men and women displayed the lowest perceptions of women as managers. Originality/Value : The results of this study build upon the extant literature and the WAMS scale offer interesting insights for international mangers on perceptions of women as managers in three distinct cultural settings and socioeconomic developments. Implications for research and practice in cross-cultural and international management shed additional light on this important topic

    Operation and restoration of bulk power systems using distributed energy resources and multi-microgrids

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    The fast-paced and meaningful penetration of distributed energy resources (DERs), such as variable renewable energy sources (RESs), concurrently with the widespread occurrence of natural disasters and man-made threats, has raised several challenges for the modern bulk power systems (BPSs) status quo. Although the DERs are demanding new solutions to ensure adequate stability and security levels, these resources enable significant opportunities to improve multiple BPS perspectives. In this view, seeking to capitalize on these novel features, while aware of the significant changes to BPS outlook, this thesis is focused on developing new methods able to capitalize on modern monitoring infrastructures, DERs and control areas opportunities toward the improvement of BPS operation and stability. Specifically, the thesis focuses on: 1) First, a novel method for the improvement of the static security region (SSR) is proposed based on a new network partitioning algorithm. The proposed algorithm focuses on modern BPS with high penetration of variable RES generation. It divides the BPS into coherence areas according to its criticality mapping, and consequently, areas are adaptively associated with SSRs generators groups. To this end, each bus is assigned a criticality index from the potential energy function, whereas this calculation is based on the data of the wide-area measurement system (WAMS) using phasor measurement unit (PMU); 2) Second, a novel area-based sensitivity index for voltage stability support is proposed, exploring both the network-wide sensitivity and the local characteristics of voltage collapse. The developed index focuses on the determination of the most effective buses for voltage support and their respective capability of increasing the system’s load margin. For this, a novel area-based outlook is developed taking advantage of the new possibilities enabled by BPS distributed controllable resources, such as flexible resources (FRs)

    Attitudes towards and Perceptions of Women Managers and Their Communication Competencies in the Sultanate of Oman

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    This study was concerned with the under-representation of women in leadership positions in the Sultanate of Oman. In particular, it focused on the attitudes of Omani people towards women as managers and the perceptions of these managers‘ communication competencies. It also explored reasons for the underrepresentation of women in managerial positions. The study investigated the topic through a feminist-research lens and used a mixed-method approach that included both quantitative and qualitative methodologies to collect the data. For quantitative data, a questionnaire survey was conducted on a convenience sample of 208 participants from the Ministry of Higher Education in Oman. The survey included two different tests: the Women as Managers Scale (WAMS) and the Communication Competencies of Women Managers Scale (CCWMS). For qualitative data, 12 Omani males and females from the Ministry were interviewed in order to gain in-depth information to complement the qualitative data. The survey data were analysed using the SPSS program while the interview transcripts were analysed using the thematic analysis technique to capture major themes that emerged from the data. The survey findings showed, first, that participants held both positive attitudes towards women in managerial positions and positive perceptions of women managers‘ communication competencies. Second, gender was not found to have significant influence on either the attitudes or the perceptions of communication competencies. Prior experience with women managers, on the other hand, did have significant influence on participants‘ perception of women managers‘ communication competencies but not on the attitudes towards these managers. The findings also indicated that there was a weak correlation between attitudes towards women managers and the perceptions of their communication competences. Finally, the findings showed a significant relationship between satisfaction of working with women managers and attitudes towards women managers, while there was no relationship between attitudes and being overseas. Thematic analysis of the interviews showed that the level of representation of women in managerial positions in Oman could be influenced by many factors educational, Managerial (professional), psychological, familial, societal, and religious. The contribution of this research lies in the following areas. First, the study helps fill the gap in knowledge identified in the review of the literature. While there is a reasonably volume of research on attitude towards women managers in a number of countries, there has been hardly any in Oman. Second, the study shows that while attitudes and perceptions towards women managers in Oman compare favourably with those in many countries, these positive attitudes and perceptions are far from universal. Some people in Oman still believe that men have more abilities than women and are more suitable to work as managers. Third, the research has highlighted the fact that although Omani women have received a great deal of support and encouragement from the Omani government in recent times, there is still much to be done to achieve proportional representation of men and women in managerial positions

    Performance Improvement of Wide-Area-Monitoring-System (WAMS) and Applications Development

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    Wide area monitoring system (WAMS), as an application of situation awareness, provides essential information for power system monitoring, planning, operation, and control. To fully utilize WAMS in smart grid, it is important to investigate and improve its performance, and develop advanced applications based on the data from WAMS. In this dissertation, the work on improving the WAMS performance and developing advanced applications are introduced.To improve the performance of WAMS, the work includes investigation of the impacts of measurement error and the requirements of system based on WAMS, and the solutions. PMU is one of the main sensors for WAMS. The phasor and frequency estimation algorithms implemented highly influence the performance of PMUs, and therefore the WAMS. The algorithms of PMUs are reviewed in Chapter 2. To understand how the errors impact WAMS application, different applications are investigated in Chapter 3, and their requirements of accuracy are given. In chapter 4, the error model of PMUs are developed, regarding different parameters of input signals and PMU operation conditions. The factors influence of accuracy of PMUs are analyzed in Chapter 5, including both internal and external error sources. Specifically, the impacts of increase renewables are analyzed. Based on the analysis above, a novel PMU is developed in Chapter 6, including algorithm and realization. This PMU is able to provide high accurate and fast responding measurements during both steady and dynamic state. It is potential to improve the performance of WAMS. To improve the interoperability, the C37.118.2 based data communication protocol is curtailed and realized for single-phase distribution-level PMUs, which are presented in Chapter 7.WAMS-based applications are developed and introduced in Chapter 8-10. The first application is to use the spatial and temporal characterization of power system frequency for data authentication, location estimation and the detection of cyber-attack. The second application is to detect the GPS attack on the synchronized time interval. The third application is to detect the geomagnetically induced currents (GIC) resulted from GMD and EMP-E3. These applications, benefited from the novel PMU proposed in Chapter 6, can be used to enhance the security and robust of power system

    Human-in-the-Loop Cyber Physical Systems: Modular Designs for Semi-Autonomous Wheelchair Navigation

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    This project involves the design and development of a prototyping platform and open design framework for a semi-autonomous wheelchair to realize a human-in-the-loop cyber physical system as an assistive technology. The system is designed to assist physically locked-in individuals in navigating indoor environments through the use of modular sensor, communication, and control designs. This enables the user to share control with the wheelchair and allows the system to operate semi-autonomously with human-in-the-loop. The Wheelchair Add-on Modules (WAMs) developed for use in this project are platform-independent and facilitate development and application of semi- autonomous functionality

    On power system automation: a Digital Twin-centric framework for the next generation of energy management systems

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    The ubiquitous digital transformation also influences power system operation. Emerging real-time applications in information (IT) and operational technology (OT) provide new opportunities to address the increasingly demanding power system operation imposed by the progressing energy transition. This IT/OT convergence is epitomised by the novel Digital Twin (DT) concept. By integrating sensor data into analytical models and aligning the model states with the observed system, a power system DT can be created. As a result, a validated high-fidelity model is derived, which can be applied within the next generation of energy management systems (EMS) to support power system operation. By providing a consistent and maintainable data model, the modular DT-centric EMS proposed in this work addresses several key requirements of modern EMS architectures. It increases the situation awareness in the control room, enables the implementation of model maintenance routines, and facilitates automation approaches, while raising the confidence into operational decisions deduced from the validated model. This gain in trust contributes to the digital transformation and enables a higher degree of power system automation. By considering operational planning and power system operation processes, a direct link to practice is ensured. The feasibility of the concept is examined by numerical case studies.The electrical power system is in the process of an extensive transformation. Driven by the energy transition towards renewable energy resources, many conventional power plants in Germany have already been decommissioned or will be decommissioned within the next decade. Among other things, these changes lead to an increased utilisation of power transmission equipment, and an increasing number of complex dynamic phenomena. The resulting system operation closer to physical boundaries leads to an increased susceptibility to disturbances, and to a reduced time span to react to critical contingencies and perturbations. In consequence, the task to operate the power system will become increasingly demanding. As some reactions to disturbances may be required within timeframes that exceed human capabilities, these developments are intrinsic drivers to enable a higher degree of automation in power system operation. This thesis proposes a framework to create a modular Digital Twin-centric energy management system. It enables the provision of validated and trustworthy models built from knowledge about the power system derived from physical laws, and process data. As the interaction of information and operational technologies is combined in the concept of the Digital Twin, it can serve as a framework for future energy management systems including novel applications for power system monitoring and control, which consider power system dynamics. To provide a validated high-fidelity dynamic power system model, time-synchronised phasor measurements of high-resolution are applied for validation and parameter estimation. This increases the trust into the underlying power system model as well as the confidence into operational decisions derived from advanced analytic applications such as online dynamic security assessment. By providing an appropriate, consistent, and maintainable data model, the framework addresses several key requirements of modern energy management system architectures, while enabling the implementation of advanced automation routines and control approaches. Future energy management systems can provide an increased observability based on the proposed architecture, whereby the situational awareness of human operators in the control room can be improved. In further development stages, cognitive systems can be applied that are able to learn from the data provided, e.g., machine learning based analytical functions. Thus, the framework enables a higher degree of power system automation, as well as the deployment of assistance and decision support functions for power system operation pointing towards a higher degree of automation in power system operation. The framework represents a contribution to the digital transformation of power system operation and facilitates a successful energy transition. The feasibility of the concept is examined by case studies in form of numerical simulations to provide a proof of concept.Das elektrische Energiesystem befindet sich in einem umfangreichen Transformations-prozess. Durch die voranschreitende Energiewende und den zunehmenden Einsatz erneuerbarer EnergietrĂ€ger sind in Deutschland viele konventionelle Kraftwerke bereits stillgelegt worden oder werden in den nĂ€chsten Jahren stillgelegt. Diese VerĂ€nderungen fĂŒhren unter anderem zu einer erhöhten Betriebsmittelauslastung sowie zu einer verringerten SystemtrĂ€gheit und somit zu einer zunehmenden Anzahl komplexer dynamischer PhĂ€nomene im elektrischen Energiesystem. Der Betrieb des Systems nĂ€her an den physikalischen Grenzen fĂŒhrt des Weiteren zu einer erhöhten StöranfĂ€lligkeit und zu einer verkĂŒrzten Zeitspanne, um auf kritische Ereignisse und Störungen zu reagieren. Infolgedessen wird die Aufgabe, das Stromnetz zu betreiben anspruchsvoller. Insbesondere dort wo Reaktionszeiten erforderlich sind, welche die menschlichen FĂ€higkeiten ĂŒbersteigen sind die zuvor genannten VerĂ€nderungen intrinsische Treiber hin zu einem höheren Automatisierungsgrad in der Netzbetriebs- und SystemfĂŒhrung. Aufkommende Echtzeitanwendungen in den Informations- und Betriebstechnologien und eine zunehmende Menge an hochauflösenden Sensordaten ermöglichen neue AnsĂ€tze fĂŒr den Entwurf und den Betrieb von cyber-physikalischen Systemen. Ein vielversprechender Ansatz, der in jĂŒngster Zeit in diesem Zusammenhang diskutiert wurde, ist das Konzept des so genannten Digitalen Zwillings. Da das Zusammenspiel von Informations- und Betriebstechnologien im Konzept des Digitalen Zwillings vereint wird, kann es als Grundlage fĂŒr eine zukĂŒnftige Leitsystemarchitektur und neuartige Anwendungen der Leittechnik herangezogen werden. In der vorliegenden Arbeit wird ein Framework entwickelt, welches einen Digitalen Zwilling in einer neuartigen modularen Leitsystemarchitektur fĂŒr die Aufgabe der Überwachung und Steuerung zukĂŒnftiger Energiesysteme zweckdienlich einsetzbar macht. In ErgĂ€nzung zu den bereits vorhandenen Funktionen moderner NetzfĂŒhrungssysteme unterstĂŒtzt das Konzept die Abbildung der Netzdynamik auf Basis eines dynamischen Netzmodells. Um eine realitĂ€tsgetreue Abbildung der Netzdynamik zu ermöglichen, werden zeitsynchrone Raumzeigermessungen fĂŒr die Modellvalidierung und ModellparameterschĂ€tzung herangezogen. Dies erhöht die Aussagekraft von Sicherheitsanalysen, sowie das Vertrauen in die Modelle mit denen operative Entscheidungen generiert werden. Durch die Bereitstellung eines validierten, konsistenten und wartbaren Datenmodells auf der Grundlage von physikalischen GesetzmĂ€ĂŸigkeiten und wĂ€hrend des Betriebs gewonnener Prozessdaten, adressiert der vorgestellte Architekturentwurf mehrere SchlĂŒsselan-forderungen an moderne Netzleitsysteme. So ermöglicht das Framework einen höheren Automatisierungsgrad des Stromnetzbetriebs sowie den Einsatz von Entscheidungs-unterstĂŒtzungsfunktionen bis hin zu vertrauenswĂŒrdigen Assistenzsystemen auf Basis kognitiver Systeme. Diese Funktionen können die Betriebssicherheit erhöhen und stellen einen wichtigen Beitrag zur Umsetzung der digitalen Transformation des Stromnetzbetriebs, sowie zur erfolgreichen Umsetzung der Energiewende dar. Das vorgestellte Konzept wird auf der Grundlage numerischer Simulationen untersucht, wobei die grundsĂ€tzliche Machbarkeit anhand von Fallstudien nachgewiesen wird
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