Open Access Zeitschriften des Universitätsverlages der Technischen Universität Chemnitz
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Individual based Modelling of Biofilm Colonisation
Get PDF Bacterial biofilms on implants or host tissue can cause unwanted infections. One of the main factors for the pathogenic biofilm growth is the initial adhesion of the bacteria. In this project a framework for systematic studies of the bacterial adhesion is provided. Therefore, an Individual based Model (IbM) is set up in the IbM solver NUFEB, an extension of the molecular dynamics code LAMMPS, which integrates Newton\u27s equations of motion for the cells that interact via various forces. Experimentally measured adhesion forces are implemented for the cell-wall and cell-cell interaction. Furthermore, the random movement of planktonic cells is included into the IbM software. A sensitivity analysis of important parameters and an exemplary simulation of the attachment are performed. Thus, the attachment of the bacterial cells and the initial growth of a biofilm can be qualitatively modelled
Monolithic, non-iterative and iterative time discretization methods for linear coupled elliptic-parabolic systems
Get PDFWe compare four numerical methods for the time discretization of linear coupled elliptic-parabolic systems.
The monolithic method arising from an implicit Euler discretization is the primary method for solving the coupled system.
Accelerated solution via non-iterative decoupling is possible by the semi-explicit Euler discretization, using a novel methodology from related delay differential equations. For poroelasticity, the fixed-stress splitting and undrained splitting methods enable iterative decoupled solves.
We present formulations for the iterative methods in an abstract form and compare through numerical experiments the a priori convergence results for the four methods
Development of an Overload Management Model in IMS
Get PDFAbstract— The concept of IP Multimedia Subsystem (IMS) describes a new network architecture, the main element of which is a packet transport network that supports all access technologies and provides implementation of a large number of infocommunication services. In this paper, formalization of the task of balancing the load of IMS virtual subsystems
A method for finding all connections in the Pantelides algorithm for delay differential-algebraic equations:
Get PDFThe Pantelides algorithm for systems of delay differential-algebraic equations (DDAEs) is a method to structurally analyse such systems with the goal to detect which equations have to be differentiated or shifted to construct a solution. In this process, one has to detect implicit connections between equations in the shifting graph, making it necessary to check all possible connections. The problem of finding these efficiently remained unsolved so far. It is explored in further detail and a reformulation is introduced. Additionally, an algorithmic approach for its solution is presented
Results of simulations of atmosphere-lake interactions using numerical model
Get PDFLakes influence the regional atmosphere through modifying thermodynamic characteristics. This study examines the effects of the Baikal lake on meteorological parameters in summertime using the numerical model. Diurnal variations in the lakes’ impact on the atmosphere are found through changing the surface energy budget, which includes changes in sensible and latent heat fluxes. The changes in heat fluxes cause relatively lower surface temperature which leads to a shallow boundary layer over the lake surfaces. Greater heat capacity in water bodies compared to grasslands causes slower heating and cooling rates in the lakes. The amplitude of air temperature over the lake surfaces is smaller than that over the grasslands. Lakes promote diverging winds near the ground, furthermore, tend to stabilize the overlying atmosphere in the summertime
Cultural influences on service quality expectation: evidence from Mongolian high education
Get PDFUniversities\u27 goal in the twenty-first century is threefold: knowledge generation, utilization, and sharing. In education, students are clients who pay to interact with institutions in order to gain knowledge and skills. To boost national competitiveness, university education should be the primary system for training and equipping people to be highly skilled, creative, inventive, and professional. As a result, assessing the quality of education services becomes critical. The study topic in this context will be how to adequately quantify service quality while taking cultural factors into account. This research will employ SERVQUAL and HOFSTEDE dimensions to explore the two concepts of service quality and culture because they are the most widely used models in their industry. The key research issue based on this problem is how culture effects service quality in a certain service context and how service quality expectations fluctuate across different types of service contexts and cultures. With the rise of online education caused by the covid19 pandemic, students from different countries and diverse cultural backgrounds seek to learn from university or instructors located in other parts of the world. These university and instructors need to understand learners’ cultural differences to provide quality education services. This makes the link between culture and service quality expectation of utmost importance. In the case of education context, Power distance has a stronger correlation with reliability and assurance. The following conclusions can be drawn from this: Mongolia has a high "power distance" culture, therefore, in the field of Mongolian education, graduates are trained to be skilled professionals, as well as job security and demand for graduates is important
Learner Centered Learning (LCL 2022) International Workshop
Get PDFThis is special issue of ESS journal for proceedings of Learner Centered Learning (LCL 2022) international workshop. The LCL workshop is organizing every two years by IBS foundation in cooperation with Computer Engineering Professorship of TU Chemnitz, Germany.First workshop organized in Laubusch by IBS Foundation in 2018 and since that time four universities from four countries cooperating together to support this event. Main aim of this workshop is to bring together professors, scholars, stakeholders of educational institutions and students together for discussion and reflection on topics: learning of learning, teaching to students of digital era, implementation of educational technologies in teaching and learning, application of artificial intelligence into higher education teaching and support of students’ success in study
Tribological and mechanical properties of lubricant filled microcapsules in thermoplastic composites
Get PDFPolymeric materials with long lifetime and low frictional energy loss are frequently required for a broad range of applications. Microencapsulation of lubricating oils by in-situ polymerization (melamine-formaldehyde) and interfacial polymerization (polyurethane/polyurea) was used to obtain free-flowing powders, which can be used as additive for thermoplastic materials resulting in microcapsule-containing self-lubricating composites. The specific functionality of such composites is achieved via portioned and localised release of the lubricant in the areas of the interface, which experiences the highest degrees of stress and wear due to the friction. Friction-triggered on-demand release of the lubricating oil results in materials with higher wear resistance and potentially leading to new products with prolonged lifetime. In this study, different ratios of microcapsules were added in polyoxymethylene (POM) and polybutylterephthalat (PBT) matrices by using laboratory scale twin-screw extruder resulting in self-lubricating composite materials. The effect of such modification on the tribological and mechanical properties of the thermoplastic composites were investigated. Rotational ball on disc tests were used to investigate the wear loss and coefficient of friction for the composites with varied microcapsule concentrations. Tensile tests revealed decreased mechanical stability for the composites with higher microcapsule content regardless of microcapsule wall material composition. Addition of 5 wt.- % of encapsulated lubricant oil led to the substantial decrease of the frictional and wear coefficients. Further increase of encapsulated lubricant oil content to 10 wt.-% had a major decreasing impact on the mechanical properties, whilst the effect on the tribological performance was rather small
Prüfung der mechanischen Zeitstandfestigkeit von Filamentgarn bei heterogenen Wirkpaarungen
Get PDFInhalt dieses Beitrages ist es, die Qualität und Eignung verfügbarer Mess- und Detektionstechnik im Zusammenhang mit der Garnprüfung darzustellen. Wie durch die Auswertung deutliche wurde, war es notwendig eine Konzipierung von Prüfständen und Prüfmethoden für neue Werkstoffe im Faserbereich und hybride textile Strukturen umzusetzen. Im Folgenden soll ein Prüfkonzept zur Garn / Garn Interaktion bei einer dynamischen, heterogenen Materialprüfung vorgestellt werden. Zur Ermittlung grundlegenden reibtechnischer Kennwerte wurden an den verschiedenen Fasermaterialien Dauerversuche bis zum Materialversagen durchgeführt. Nach den Vorversuchen zur Parametrisierung konnten sich die eigentlichen Reibversuchen zwischen Hochleistungs- und Massenfasern anschschließen
Categorization of Learning Analytics Models: Brief Literature Review
Get PDFLearning analytics is one of the technological tools aiming to investigate educational database collected during the learning delivery process for further purpose of use in decision making or process update. Various types of methods on learning analytics are originated by scholars with their own ambition to contribute the field study. It is emerging study field since 2010s. This paper review literature papers which focused on categorization of learning analytics models with focus of its’ criteria. The papers are chosen from open scholar databases. The selected papers reviewed learning analytics model related studies to bring up their suggested categorization. The category based on the learning analytics models’ main objective as well as used approach. It is observed that prediction of student achievement or success is significant method among learning analytics models