Optimal Excitation Controller Design for Wind Turbine Generator

An optimal excitation controller design based on multirate-output controllers (MROCs) having a multirate sampling mechanismwith different sampling period in each measured output of the system is presented. The proposed H∞ -control techniqueis applied to the discrete linear open-loop system model which represents a wind turbine generator supplying an infinite busthrough a transmission line

Diffuse large B-cell lymphoma arising from a multicentric mixed variant of Castleman's disease

This case report describes a patient with multicentric mixed type Castleman\u2032s disease and concomitant non-Hodgkin\u2032s lymphoma of diffuse large B cell type in the neck. Multicentric CD is a systemic illness with disseminated lymphadenopathy; its aggressive and usually fatal course is associated with infectious complications and risk for malignant tumors, such as lymphoma or Kaposi sarcoma

Learning episodes in an intercultural virtual exchange: The case of social high-immersion virtual reality

Computer-mediated communication tools facilitate international collaboration projects between foreign language learners and peers abroad (O’Dowd, 2018). Social Virtual Reality (VR) applications allow for synchronous interactions and task-based communication in which learners can experience telepresence and immersion and conversate in a foreign language. Based on previous pilot experiences (Jauregi-Ondarra, Gruber, & Canto, 2020, 2021), this Virtual Exchange (VE) project aims to investigate how the specific affordances of Social High-immersion VR (SHiVR) in conjunction with designed tasks influence interaction patterns, and learning episodes. The VE took place between two groups of university students in the Netherlands (N=15) and Cyprus (N=14) through SHiVR in March 2022. The main aims of the tasks were to raise student intercultural awareness, stimulate task-based communication processes using English as a lingua franca and digital pedagogical competences of language education students. Different sources of data were gathered and analysed. In this paper, we describe and present the pedagogical experience and the initial result

Initiating meaningful social interactions in a high-immersion self-access language learning space

Virtual Reality (VR) has paved the way for learner interaction in immersive environments, simulating authentic cultural conditions in the target language and encouraging collaborative opportunities. This article describes how the high-immersion VR social application AltspaceVR served as an immersive Self-Access Language Learning (SALL) space in a collaborative online international learning (COIL)

Discrete Optimal Multirate Techniques for Excitation Controller Design of a Synchronous Machine

An optimal control strategy based on Two-Point-Multirate Controllers (TPMRCs), is used to design a desirable excitation controller of a hydrogenerator system, in order to enhance its dynamic stability characteristics. In the TPMRCs based scheme, the control is constrained to a certain piecewise constant signal, while each of the controlled plant outputs is detected many times over a fundamental sampling period T0. On the basis on this strategy, the original problem is reduced to an associate discrete-time linear quadratic (LQ) regulation problem for the performance index with cross product terms, for which a fictitious static state feedback controller is needed to be computed. Simulation results for the actual 117 MVA synchronous generator with conventional exciter supplying line to an infinite grid show the effectiveness of the proposed method which has a quite satisfactory performance

A stromal myoid cell line provokes thymic erythropoiesis between 16th to 20th weeks of intrauterine life

Background: The thymus provides an optimal cellular and humoral microenvironment for cell line committed differentiation of haematopoietic stem cells. The immigration process requires the secretion of at least one peptide called thymotaxine by cells of the reticulo-epithelial (RE) network of the thymic stromal cellular microenvironment. The thymic RE cells are functionally specialised based on their intrathymic location and this differentiation is modulated by various interaction signals of differentiating thymocytes and other non lymphatic haematopoietic stem cells. Objectives: To study the role of another cell line in fetal thymic haematopoietic proliferation and differentiation in different stages of development: the stromal myoid cells. Design: Fifteen cases of fetal thymic specimens (4th to 8th weeks: five cases 16th to 20th weeks: five cases and 28th to 32nd weeks: five cases respectively) were studied. Tissue paraffin samples were stained immunohistochemically using (i) a monoclonal antibody recognising alpha-smooth muscle actin, a contractile microfilament expressed exclusively by smooth muscle cells, myofibroblasts and related cells, (ii) a monoclonal antibody glycophorin C recognising the erythropoietic cells. Setting: Histology - Embryology Department of Democritus University of Thrace (Alexandroupolis) over ten year period (1991-2001). Results: The number of alpha-smooth muscle actin - positive cells significantly increased during the late second and third trimester of gestation. In the above period a relevant increase in the number of glycophorin C positive cells were observed. Conclusion: Our data suggest that a myoid cell line is involved in the formation of an appropriate microenvironment for homing and proliferation of erythropoietic cells. East African Medical Journal Vol. 81 No. 2 February 2004: 78-8