Applying series braking resistors to improve the stability of low inertia synchronous generators

Widely held concerns over the environmental impact of emissions from large fossil fuelled generating plants are serving to promote the connection of renewable or sustainable generation onto distribution networks. Many such generators are synchronous machines with low values of inertia, and thus possess short critical clearance times to avoid the onset of transient instability. With fault clearance times of up to 1s occurring in distribution networks, there is the potential for a growing problem as distributed generation makes up a larger proportion of installed capacity. This paper proposes the use of series braking resistors that are switched into circuit at the generator terminals as a means of improving transient stability, and thus avoid, or at least defer major upgrades to distribution system protectio

ImmunoCap 250 for Diagnostics of Allergy and Autoimmunity

As HLS EU International coordinator, I have planned and led DMUglobal trips for students and staff in 2019 and 2020 to Vilnius Life Science Centre and the COINS Life Science conference, this poster has been presented at this conference in 2020.See Abstract Booklet p.4

El clima de aula según becarios 18 y alumnos regulares de una universidad privada de Lima

The admission of poor students sponsored by the Beca 18 social program into Lima universities is a recent phenomenon that requires studies on their adjustment and academic performance. This research targeted Beca 18 students at USIL and compared their responses to a questionnaire on perceptions of classroom climate with those from regular students. Both were participating in the course on math analysis offered to engineering students. In the general context of positive perceptions of classroom climate, Beca 18 students slightly differed from regular students, showing more positive perceptions of professor’s behavior in terms of creation of a working environment, class pace, interest in the student, and promotion of cooperation and group work. A greater difference was observed in regard of the avoidance of a climate of competition, which should be studied in greater depth. On the other hand, Beca 18 students complained more about the lack of solidarity, which can be explained by their adaptation to the more co lectivistic culture observed in Peruvian provinces.La inserción de beneficiarios pobres del programa social Beca 18 en universidades limeñas es un fenómeno reciente que amerita estudios relativos a su adaptación y desempeño académico. En la presente investigación se analizaron las respuestas de becarios 18 en USIL a un cuestionario de percepciones del clima de aula, y se les comparó con las de alumnos regulares para establecer si había diferencias. Ambos participaban en el Curso de Análisis Matemático que se imparte a estudiantes de ingeniería. En el contexto general de climas de aula bastante positivos, los becarios se diferenciaron ligeramente de los alumnos regulares por una percepción más positiva del comportamiento del profesor en términos del ambiente de trabajo creado, el ritmo de la clase, el interés por el estudiante y el fomento de la cooperación y trabajo grupal. Mayor diferencia se observó respecto a la evitación de un clima de competición; esto debería investigarse a mayor profundidad. De otro lado, los becarios se quejaron más de la falta de ayu da por parte de otros alumnos, lo cual se explica por la mayor solidaridad existente en provincias, cuya población es más colectivista que la de Lima.La inserción de beneficiarios pobres del programa social Beca 18 en universidades limeñas es un fenómeno reciente que amerita estudios relativos a su adaptación y desempeño académico. En la presente investigación se analizaron las respuestas de becarios 18 en USIL a un cuestionario de percepciones del clima de aula, y se les comparó con las de alumnos regulares para establecer si había diferencias. Ambos participaban en el Curso de Análisis Matemático que se imparte a estudiantes de ingeniería. En el contexto general de climas de aula bastante positivos, los becarios se diferenciaron ligeramente de los alumnos regulares por una percepción más positiva del comportamiento del profesor en términos del ambiente de trabajo creado, el ritmo de la clase, el interés por el estudiante y el fomento de la cooperación y trabajo grupal. Mayor diferencia se observó respecto a la evitación de un clima de competición; esto debería investigarse a mayor profundidad. De otro lado, los becarios se quejaron más de la falta de ayu da por parte de otros alumnos, lo cual se explica por la mayor solidaridad existente en provincias, cuya población es más colectivista que la de Lima

El clima de aula según becarios 18 y alumnos regulares de una universidad privada de Lima

The admission of poor students sponsored by the Beca 18 social program into Lima universities is a recent phenomenon that requires studies on their adjustment and academic performance. This research targeted Beca 18 students at USIL and compared their responses to a questionnaire on perceptions of classroom climate with those from regular students. Both were participating in the course on math analysis offered to engineering students. In the general context of positive perceptions of classroom climate, Beca 18 students slightly differed from regular students, showing more positive perceptions of professor’s behavior in terms of creation of a working environment, class pace, interest in the student, and promotion of cooperation and group work. A greater difference was observed in regard of the avoidance of a climate of competition, which should be studied in greater depth. On the other hand, Beca 18 students complained more about the lack of solidarity, which can be explained by their adaptation to the more co lectivistic culture observed in Peruvian provinces.La inserción de beneficiarios pobres del programa social Beca 18 en universidades limeñas es un fenómeno reciente que amerita estudios relativos a su adaptación y desempeño académico. En la presente investigación se analizaron las respuestas de becarios 18 en USIL a un cuestionario de percepciones del clima de aula, y se les comparó con las de alumnos regulares para establecer si había diferencias. Ambos participaban en el Curso de Análisis Matemático que se imparte a estudiantes de ingeniería. En el contexto general de climas de aula bastante positivos, los becarios se diferenciaron ligeramente de los alumnos regulares por una percepción más positiva del comportamiento del profesor en términos del ambiente de trabajo creado, el ritmo de la clase, el interés por el estudiante y el fomento de la cooperación y trabajo grupal. Mayor diferencia se observó respecto a la evitación de un clima de competición; esto debería investigarse a mayor profundidad. De otro lado, los becarios se quejaron más de la falta de ayu da por parte de otros alumnos, lo cual se explica por la mayor solidaridad existente en provincias, cuya población es más colectivista que la de Lima.La inserción de beneficiarios pobres del programa social Beca 18 en universidades limeñas es un fenómeno reciente que amerita estudios relativos a su adaptación y desempeño académico. En la presente investigación se analizaron las respuestas de becarios 18 en USIL a un cuestionario de percepciones del clima de aula, y se les comparó con las de alumnos regulares para establecer si había diferencias. Ambos participaban en el Curso de Análisis Matemático que se imparte a estudiantes de ingeniería. En el contexto general de climas de aula bastante positivos, los becarios se diferenciaron ligeramente de los alumnos regulares por una percepción más positiva del comportamiento del profesor en términos del ambiente de trabajo creado, el ritmo de la clase, el interés por el estudiante y el fomento de la cooperación y trabajo grupal. Mayor diferencia se observó respecto a la evitación de un clima de competición; esto debería investigarse a mayor profundidad. De otro lado, los becarios se quejaron más de la falta de ayu da por parte de otros alumnos, lo cual se explica por la mayor solidaridad existente en provincias, cuya población es más colectivista que la de Lima

Predictors of review sites usage in hotels

The tourism industry has been strongly impacted by the consumer use of review sites. Since review travel sites such as TripAdvisor allowed accommodations to create own profiles with information, hotels began incorporating these actions into their engaging customers programming. Despite the benefits that review sites can offer to customers, hotels and accommodations, its implementation is not developed and exploited in all its possibilities, and little is known about hotels use of this review sites. This study explores the topic trough quantitative methodology, conducting multiple correlation analysis of data obtained from a sample of 301 hotel managers. Managers consider they are committed to this type of platforms and are capable of use it accurately. Also it was found evidence of correlation between use of TripAdvisor and hotel characteristics (size, ownership structure, and category). Furthermore, multiple regression analysis shows competence and commitment as the most important predictors of use intensity

Generator response following as a primary frequency response control strategy for VSC-HVDC connected offshore wind farms

The present study attempts to collect relevant research on the subject of synthetic inertia control strategies for VSC-HVDC transmission links, particularly those connected to offshore windfarms. A number of ideas have been proposed in literature. First, various control strategies at the grid side converter interfacing the DC link with the AC power system are presented. This includes strategies exploiting the power-frequency relationship that naturally exists in AC systems with a high X/R ratio. Other strategies utilize the voltage-frequency relationship that exists when the DC link capacitor is asked to provide active power injection or absorption in response to frequency deviations. Then some coordinated strategies are outlined which build upon and combine other strategies (including those associated with traditional synchronous machines) in order to enhance the operational capability of the decoupled non-synchronous system with respect to synthetic inertia services. Some options for communication are also identified

Stabilized mixed approximation of axisymmetric Brinkman flows

This paper is devoted to the numerical analysis of an augmented finite element approximation of the axisymmetric Brinkman equations. Stabilization of the variational formulation is achieved by adding suitable Galerkin least-squares terms, allowing us to transform the original problem into a formulation better suited for performing its stability analysis. The sought quantities (here velocity, vorticity, and pressure) are approximated by Raviart−Thomas elements of arbitrary order k ≥ 0, piecewise continuous polynomials of degree k + 1, and piecewise polynomials of degree k, respectively. The well-posedness of the resulting continuous and discrete variational problems is rigorously derived by virtue of the classical Babuška–Brezzi theory. We further establish a priori error estimates in the natural norms, and we provide a few numerical tests illustrating the behavior of the proposed augmented scheme and confirming our theoretical findings regarding optimal convergence of the approximate solutions