Ternäre polymerhaltige Lösungen - Phasenverhalten und Grenzflächenspannung

Im Rahmen dieser Arbeit wurden experimentelle und theoretische Untersuchungen zum Phasen- und Grenzflächenverhalten von ternären Systemen des Typs Lösungsmittel/Fällungsmittel/Polymer durchgeführt. Diese Art der Mischungen ist vor allem für die Planung und Durchführung der Membranherstellung von Bedeutung, bei der die genaue Kenntnis des Phasendiagramms und der Grenzflächenspannung unabdingbar ist. Als Polymere dienten Polystyrol sowie Polydimethylsiloxan. Im Fall des Polystyrols kam Butanon-2 als Lösungsmittel zum Einsatz, wobei drei niedrigmolekulare lineare Alkohole als Fällungsmittel verwendet wurden. Für Polydimethylsiloxan eignen sich Toluol als Lösungsmittel und Ethanol als Fällungsmittel. Durch Lichtstreumessungen, Dampfdruckbestimmungen mittels Headspace-Gaschromatographie (VLE-Gleichgewichte) sowie Quellungsgleichgewichten lassen sich die thermodynamischen Eigenschaften der binären Subsysteme charakterisieren. Auf Grundlage der Flory-Huggins-Theorie kann das experimentell bestimmte Phasenverhalten (LLE-Gleichgewichte) in guter Übereinstimmung nach der Methode der Direktminimierung der Gibbs'schen Energie modelliert werden. Zieht man die Ergebnisse der Aktivitätsbestimmung von Dreikomponenten-Mischungen mit in Betracht, so ergeben sich systematische Abweichungen zwischen Experiment und Theorie. Sie können auf die Notwendigkeit ternärer Wechselwirkungsparameter zurückgeführt werden, die ebenfalls durch Modellierung zugänglich sind.Durch die aus den VLE- und LLE-Untersuchungen gewonnenen Ergebnissen kann die sog. Hump-Energie berechnet werden, die ein Maß für die Entmischungstendenz darstellt. Diese Größe eignet sich gut zur Beschreibung von Grenzflächenphänomenen mittels Skalengesetzen. Die für binäre Systeme gefundenen theoretisch fundierten Skalenparameter gelten jedoch nur teilweise. Ein neues Skalengesetz lässt erstmals eine Beschreibung über die gesamte Mischungslücke zu, wobei ein Parameter durch eine gemessene Grenzflächenspannung (zwischen Fällungsmittel/Polymer) ersetzt werden kann.

Web-based education in Spanish Universities. A Comparison of Open Source E-Learning Platforms

Web-based education or „e-learning‟ has become a critical component in higher education for the last decade, replacing other distance learning methods, such as traditional computer training or correspondence learning. The number of university students who take on-line courses is continuously increasing all over the world. In Spain, nearly a 90% of the universities have an institutional e-learning platform and over 60% of the traditional on-site courses use this technology as a supplement to the traditional face-to-face classes. This new form of learning allows the disappearance of geographical barriers and enables students to schedule their own learning process, among some other advantages. On-line education is developed through specific software called „e-learning platform‟ or „virtual learning environment‟ (VLE). A considerable number of web-based tools to deliver distance courses are currently available. Open source software packages such as Moodle, Sakai, dotLRN or Dokeos are the most commonly used in the virtual campuses of Spanish universities. This paper analyzes the possibilities that virtual learning environments provide university teachers and learners and offers a technical comparison among some of the most popular e-learning learning platforms.

Ensino da avaliação perceptivoauditiva da voz por meio de um ambiente virtual de aprendizagem

A avaliação vocal é realizada predominantemente por meio da avaliação perceptivoauditiva, sendo dependente de conhecimentos teóricos prévios e de treinamento prático e dinâmico. Entretanto, ainda são escassas as iniciativas educacionais que se utilizam das novas tecnologias para o ensino da avaliação perceptivoauditiva da voz. A utilização de estratégias com novas tecnologias de informação e comunicação, hoje tão presentes e familiarizadas no meio universitário, apresentam o intuito de facilitar e otimizar o processo de ensino e aprendizagem. Desta forma, este estudo teve o propósito de elaborar e avaliar um curso a distância em um ambiente virtual de aprendizagem sobre essa temática. Elaborou-se um curso a distância sobre a avaliação perceptivoauditiva da voz organizado em quatro módulos principais: 1. Noções básicas de anatomia e fisiologia da fonação; 2. Ouvindo vozes; 3. Avaliação perceptivoauditiva da voz e 4. Aplicabilidade da avaliação perceptivoauditiva da voz, além de um adicional com vídeos sobre curiosidades e sugestão de material complementar para estudo. O ambiente virtual de aprendizagem (AVA) também apresentou diversas ferramentas educacionais como textos, imagens ilustrativas, videoaulas, vídeos, arquivos de áudio, atividades práticas individuais, fóruns, além de recursos de interatividade entre alunos e tutora. Este material foi antecipadamente avaliado por três especialistas que avaliaram o material positivamente como uma inovadora e importante ferramenta educacional que poderá ser utilizada na formação de estudantes na área de voz. Foram convidados a participar do curso a distância, 133 alunos do 1o ao 4o ano de um curso de graduação em Fonoaudiologia de uma Universidade do interior paulista. Concordaram em participar 33 estudantes e desses, nove concluíram o curso. Os alunos responderam a avaliações de conteúdo nos momentos pré e pós-curso, de forma presencial e a avaliações de cada módulo, realizadas por meio de questões específicas e atividades práticas, no próprio site. Ao término do curso os alunos também responderam a uma avaliação motivacional do AVA. Observou-se diferença estatisticamente significante na média de acertos nas provas pré e pós-curso dos alunos, nas questões teóricas (p= 0,031), nas práticas (p=0,000) e no total (p=0,002), demonstrando que o material elaborado foi capaz de aumentar o conhecimento dos estudantes a respeito de seu tema. O AVA apresentou alto índice de satisfação motivacional e foi avaliado por todos os participantes como um curso impressionante, de acordo com o instrumento de avaliação motivacional utilizado. Conclui-se que foi possível elaborar um ambiente virtual de aprendizagem (AVA), em formato de curso a distância, sobre a temática da avaliação perceptivoauditiva da voz e que o material elaborado apresenta um importante potencial de ensino e aprendizagem sobre esse tema.

A novel hybrid simulation-optimization approach for the optimal design of multicomponent distillation columns

Póster presentado en Escape 22, European Symposium on Computer Aided Process Engineering, University College London, UK, 17-20 June 2012.

Vapor-liquid equilibria using the Gibbs energy and the common tangent plane criterion

Phase thermodynamics is often perceived as a difficult subject that many students never become fully comfortable with. The Gibbsian geometrical framework can help students to gain a better understanding of phase equilibria. An exercise to interpret the vapor-liquid equilibrium of a binary azeotropic mixture, using the equilibrium condition based on the common tangent plane criterion (the Gibbs stability test), is presented in this paper. From a T-composition phase diagram for the mixture, the temperature is set at different values: above, intermediate to, and below the boiling temperatures of the pure components, to intersect different regions of the system. Students prepare an Excel spreadsheet where the Gibbs energy of mixing of the vapor and liquid mixtures are calculated and represented over the whole range of compositions and then, apply the Gibbs stability test to ascertain the aggregation state of the system and to calculate the VL phase equilibrium compositions. Finally, Matlab is used to generate the 3D Gibbs energy of mixing surfaces for both phases over the whole range of temperatures which facilitates the geometrical interpretation of the vapor-liquid equilibrium.

A hybrid simulation-optimization approach for the design of internally heat-integrated distillation columns

Paper submitted to AIChE 2012 Annual Meeting: Energy Efficiency by Process Intensification, Pittsburgh, PA, October 28-November 2, 2012.

Mejoras en la portabilidad de la integración de EvalCOMIX en Moodle 2.X

EvalCOMIX es un servicio Web de autoría y despliegue de instrumentos que una vez integrado con Moodle permite el uso de dichos instrumentos para la evaluación de distintas actividades realizadas por los alumnos. La evaluación podrá ser realizada tanto por parte del docente como por parte de los propios alumnos a sí mismos o al resto de compañeros. La primera integración de esta herramienta fue realizada para la versión 1.9 de Moodle. Para la integración de la versión 2.X de Moodle se ha decidido realizar mejoras en distintos aspectos. Uno de ellos es la portabilidad de la integración, la cual depende intrínsecamente de su procedimiento de instalación.

Liquid–Liquid, Vapor–Liquid, and Vapor–Liquid–Liquid Equilibrium Data for the Water–n-Butanol–Cyclohexane System at Atmospheric Pressure: Experimental Determination and Correlation

The temperature and the composition of the vapor–liquid–liquid equilibrium (VLLE) and the vapor–liquid equilibrium (VLE) of a ternary mixture of water–n-butanol–cyclohexane were measured at atmospheric pressure (101.32 kPa) in a modified dynamic recirculating still. As found in the literature, the experimental data obtained reveal a ternary azeotrope at 341.86 K with a mole fraction composition of 0.281, 0.034, and 0.685 water, n-butanol, and cyclohexane, respectively. The liquid–liquid equilibrium (LLE) compositions were measured at a constant temperature of 313.15 K and compared with data in the literature collected at other temperatures. Thermodynamic consistency of all the experimental data was demonstrated. The universal quasichemical (UNIQUAC) and the nonrandom two-liquid (NRTL) thermodynamic models were used to correlate the VLE and LLE data, while the original universal functional (UNIFAC) model was used to compare the predicted data.

Phase equilibria of the water + 1-butanol + toluene ternary system at 101.3 kPa

Isobaric vapour–liquid and vapour–liquid–liquid equilibrium data for the water + 1-butanol + toluene ternary system were measured at 101.3 kPa with a modified VLE 602 Fischer apparatus. In addition, the liquid–liquid equilibrium data at 313.15 K were measured and compared with data from other authors at different temperatures. The system exhibits a ternary heterogeneous azeotrope whose temperature and composition have been determined by interpolation. The thermodynamic consistency of the experimental vapour–liquid and vapour–liquid–liquid data was checked by means of the Wisniak’s Li/Wi consistency test. Moreover, the vapour–liquid and the liquid–liquid equilibrium correlation for the ternary system with NRTL and UNIQUAC models, together with the prediction made with the UNIFAC model, were studied and discussed.

Gibbs Energy of Mixing Function: Topological Analysis in Azeotropic Systems

ESAT 2014. 27th European Symposium on Applied Thermodynamics, Eindhoven University of Technology, July 6-9, 2014.

Comparing Common Data Environment Platforms for Student Collaborative Working: A Case Study from Ulster University

PAS1192-2 (2013) outlines the “fundamental principles of Level 2 information modeling”, one of these principles is the use of what is commonly referred to as a Common Data Environment (CDE). A CDE could be described as an internet-enabled cloudhosting platform, accessible to all construction team members to access shared project information. For the construction sector to achieve increased productivity goals, the next generation of industry professionals will need to be educated in a way that provides them with an appreciation of Building Information Modelling (BIM) working methods, at all levels, including an understanding of how data in a CDE should be structured, managed, shared and published. This presents a challenge for educational institutions in terms of providing a CDE that addresses the requirements set out in PAS1192-2, and mirrors organisational and professional working practices without causing confusion due to over complexity. This paper presents the findings of a two-year study undertaken at Ulster University comparing the use of a leading industry CDE platform with one derived from the in-house Virtual Learning Environment (VLE), for the delivery of a student BIM project. The research methodology employed was a qualitative case study analysis, focusing on observations from the academics involved and feedback from students. The results of the study show advantages for both CDE platforms depending on the learning outcomes required.

Dějiny Čech a Moravy nové doby.

Issued in parts.

Industri- och slöjdutställningen i Gefle 1901 : officiell berättelse /

Includes one folded map.

Adsorption of ethylene on graphitized thermal carbon black and in slit pores: A computer simulation study

In this paper, we studied vapor-liquid equilibria (VLE) and adsorption of ethylene on graphitized thermal carbon black and in slit pores whose walls are composed of graphene layers. Simple models of a one-center Lennard-Jones (LJ) potential and a two-center united atom (UA)-LJ potential are investigated to study the impact of the choice of potential models in the description of VLE and adsorption behavior. Here, we used a Monte Carlo simulation method with grand canonical Monte Carlo (GCMC) and Gibbs ensemble Monte Carlo ensembles. The one-center potential model cannot describe adequately the VLE over the practical range of temperature from the triple point to the critical point. On the other hand, the two-center potential model (Wick et al. J. Phys. Chem. B 2000, 104, 8008-8016) performs well in the description of VLE (saturated vapor and liquid densities and vapor pressure) over the wide range of temperature. This UA-LJ model is then used in the study of adsorption of ethylene on graphitized thermal carbon black and in slit pores. Agreement between the GCMC simulation results and the experimental data on graphitized thermal carbon black for moderate temperatures is excellent, demonstrating that the potential of the GCMC method and the proper choice of potential model are essential to investigate adsorption. For slit pores of various sizes, we have found that the behavior of ethylene exhibits a number of features that are not manifested in the study of spherical LJ particles. In particular, the singlet density distribution versus distance across the pore and the angle between the molecular axis and the z direction provide rich information about the way molecules arrange themselves when the pore width is varied. Such an arrangement has been found to be very sensitive to the pore width.

A conceptual model of personalized virtual learning environments

The Virtual Learning Environment (VLE) is one of the fastest growing areas in educational technology research and development. In order to achieve learning effectiveness, ideal VLEs should be able to identify learning needs and customize solutions, with or without an instructor to supplement instruction. They are called Personalized VLEs (PVLEs). In order to achieve PVLEs success, comprehensive conceptual models corresponding to PVLEs are essential. Such conceptual modeling development is important because it facilitates early detection and correction of system development errors. Therefore, in order to capture the PVLEs knowledge explicitly, this paper focuses on the development of conceptual models for PVLEs, including models of knowledge primitives in terms of learner, curriculum, and situational models, models of VLEs in general pedagogical bases, and particularly, the definition of the ontology of PVLEs on the constructivist pedagogical principle. Based on those comprehensive conceptual models, a prototyped multiagent-based PVLE has been implemented. A field experiment was conducted to investigate the learning achievements by comparing personalized and non-personalized systems. The result indicates that the PVLE we developed under our comprehensive ontology successfully provides significant learning achievements. These comprehensive models also provide a solid knowledge representation framework for PVLEs development practice, guiding the analysis, design, and development of PVLEs. (c) 2005 Elsevier Ltd. All rights reserved.