Search results for "Linea"
showing 10 items of 7724 documents
Revista electrónica de investigación y evaluación educativa
2014
Resumen tomado de la publicación Título, resumen y palabras clave en inglés y español Se muestra que cuando se quiere conocer el grado de satisfacción del alumno con la docencia recibida, es aconsejable introducir en su análisis y estudio componentes contextuales. Las variables contextuales que se incluyen en el análisis están relacionadas con determinadas estructuras académicas de carácter organizativo. Estas estructuras son de tipo jerárquico o anidado y aportan información sobre datos como el tipo de estudios que el alumno realiza o la clase en la que el alumno está matriculado. Para obtener el nivel de satisfacción del alumnado se utilizan los cuestionarios de evaluación docente de la U…
The Influence of Student Abilities and High School on Student Growth: A Case Study of Chinese National College Entrance Exam
2019
Enabled by available educational data and data mining techniques, educational data analysis has become a hot topic. Current researches mainly focus on the prediction of problems and performance rather than revealing the underlying causal relationships. Based on a unique exam data, we extracted the abilities of examinee from HSEE (High School Entrance Exam) based on the knowledge of educational experts, then we measured student growth from middle school to high school in total score and subject scores. We studied the impact of high school ranking and student abilities of HSEE on student growth by multiple linear regression model, in which high school ranking is divided into 5 levels, Level 1…
Demo 5. Choques y explosiones sobre un carril
2013
Objetivo: Demostrar la conservación del momento lineal en choques (elásticos e inelásticos) y explosiones, para distintos valores de la masa de los cuerpos involucrados.
APROXIMACIÓN CONCEPTUAL Y PRÁCTICA A LOS MODELOS DE ECUACIONES ESTRUCTURALES
2017
En el presente trabajo se expone una aproximación conceptual y práctica a los Modelos de Ecuaciones Estructurales o Structural Equation Modeling (SEM). Los SEM están considerados entre las herramientas más potentes para el estudio de relaciones causales en datos no experimentales. Son una combinación del análisis factorial y la regresión múltiple y están compuestos por dos componentes: el modelo de medida y el modelo estructural. El modelo de medida describe la relación existente entre una serie de variables observables; mientras que en el modelo estructural se especifican las relaciones hipotetizadas entre las variables, es decir, se describen las relaciones entre las variables latentes me…
A Nonlinear Control of Synchronous Reluctance Motors (SynRM) Based on Feedback Linearization Considering the Self and Cross-Saturation Effects
2019
This paper proposes a nonlinear controller based on feedback linearization for Synchronous Reluctance Motors (SynRM) drives that takes into consideration the self and cross-saturation effects. Such control technique permits the dynamics of both the speed and flux loops to be maintained constant independently from the load and the saturation of the iron core. The proposed technique has been tested experimentally on a suitably developed test set-up.
Non-linear interactions of femtosecond laser pulses with graphene : photo-oxidation, imaging and photodynamics
2017
This thesis presents a study focused on interactions of femtosecond laser pulses with graphene, a one atom thick carbon membrane. Graphene, which exhibits exceptional electronic and optoelectronic properties, could provide considerable advantage over current silicon-based electronics. Graphene alone, being semi-metal, is not sufficient for electronic applications, but requires modification. For this, a set of methods for modifying and measuring the properties of graphene was developed. With the perspective of making graphene a suitable component for electronics, optoelectronics or photonics, ultrashort laser pulses were used for drawing patterns on graphene. The procedure modifies graphene …
Soliton solutions for an higher order nonlinear Schroedinger equation in optical fiber
2008
The new improvements to increase the bit rate in optical fiber require the propagation of pulse whose temporal width is always lesser. This causes the presence of further terms, linear and nonlinear, in the evolution equation of the pulse. The analysis on the complete integrability of the evolution equation, in a fiber optics with local properties and achieved in a previous paper, is improved dealing with the normal dispersion case, which allows the dark soliton propagation. In the last section special efforts are made to propose some interesting soliton solutions both bright and dark.
Performance analysis of dual-pump nonlinear amplifying loop mirror mode-locked all-fibre laser
2019
We numerically characterise, in the three-dimensional space of adjustable cavity parameters, the performance of a recently reported layout of a flexible figure-8 laser having two independently pumped segments of active fibre in its bidirectional ring (Smirnov et al 2017 Opt. Lett. 42 1732–5). We show that this optimisation problem can be efficiently addressed by applying a regression model based on a neural-network algorithm.
Systems level approach reveals the correlation of endoderm differentiation of mouse embryonic stem cells with specific microstructural cues of fibrin…
2014
Stem cells receive numerous cues from their associated substrate that help to govern their behaviour. However, identification of influential substrate characteristics poses difficulties because of their complex nature. In this study, we developed an integrated experimental and systems level modelling approach to investigate and identify specific substrate features influencing differentiation of mouse embryonic stem cells (mESCs) on a model fibrous substrate, fibrin. We synthesized a range of fibrin gels by varying fibrinogen and thrombin concentrations, which led to a range of substrate stiffness and microstructure. mESCs were cultured on each of these gels, and characterization of the diff…
Financial Stress and Basis in Energy Markets
2021
We investigate the relationship between energy commodities bases, inventory and financial stress from 1994 to 2018. We find that, from the 1998 Asian crisis the effect of financial stress on energy commodities bases gradually increased and from the 2008 crisis became positive, while the effect of inventory showed a gradual decline over time. The reactions of bases to changes in financial stress is nonlinear, as they are higher in the high financial stress periods. This is more profound in crude oil market than heating oil and natural gas. Moreover, the reactions of bases to the changes in inventory is nonlinear, as the reactions are lower when the inventory level is high confirming the theo…