Object-oriented modelling of solar district heating grids with underground thermal energy storage

The transformation of the heating sector towards renewable energy sources is a key element for the mitigation of man-made climate change. In this regard, solar thermal energy is a particularly well-suited solution, as it is a simple, cost-efficient and proven technology. A main barrier for a more widespread use, is the seasonal mismatch of heat demands and solar yields, which usually limits the solar share on the overall heat supply of district energy systems to about 20%. It is therefore necessary to store the abundant solar energy supply during summer for several months to be able to use it in winter. Underground thermal energy storage (UTES) is currently the most promising technology for such applications, as it shows a high maturity level in comparison to other technologies and facilitates storage of thermal energy on a district scale. Integration of UTES into solar district heating (SDH) systems is commonly accompanied by further technologies, such as geothermal energy, industrial waste heat or power-to-heat applications, resulting in complex energy systems. These SDH-UTES systems require a thorough design of component dimensions, system layouts and control strategies to ensure security of supply, while avoiding costly overdimensioning of generation capacities. Therefore, dynamic system simulations are used for system design, as they consider the temporal distribution of heat supplies and demands as well as the strong interactions between components. The modelling language Modelica constitutes a powerful conceptual approach for modelling and simulation of thermal energy systems and is therefore applied increasingly. However, to exploit Modelica’s numerous advantages for the simulation of SDH-UTES systems and reach a large number of users, adequate model libraries are required. These should be accurate in their representation of physical components, easy to use and have a low numerical effort. The presented cumulative dissertation and the corresponding publications in scientific journals demonstrate the development of such a model library called MoSDH (Modelica Solar Dis-trict Heating). The library consists of components for the accurate, efficient, user friendly and robust simulation of such systems, including models for UTES technologies which were previously not implemented for Modelica. Selected models and aspects were already presented and demonstrated in case studies in the above-mentioned journal papers. The presented thesis contains a comprehensive description of the model components as well as the general system modelling concept. Furthermore, several case studies are used to highlight certain key functionalities and demonstrate the accurate representation of the physical systems in a numerically efficient way. The models can be used for extensive optimization studies as well as detailed investigations of certain specific aspects. In addition to that, the object-oriented modelling approach facilitates the easy adaption and reuse of model components. Finally, MoSDH is used to investigate the transition of a sub-grid of the TU Darmstadt university district heating (DH) system into a SDH-UTES system, demonstrating the possibility of those systems to satisfy the universities emission saving goals in a cost-efficient way

Best Practices for Educational Interpreters in South Carolina

The purpose of this reference is to provide districts, charter schools, and state operated programs with best practices for working with educational interpreters including, but not limited to, roles and responsibilities, code of professional conduct, and suggested credentialing. It is not required by regulation but is simply the most up-to-date recommendation from the field

Electrospun PLLA Nanofiber Scaffolds and Their Use in Combination with BMP-2 for Reconstruction of Bone Defects

Introduction Adequate migration and differentiation of mesenchymal stem cells is essential for regeneration of large bone defects. To achieve this, modern graft materials are becoming increasingly important. Among them, electrospun nanofiber scaffolds are a promising approach, because of their high physical porosity and potential to mimic the extracellular matrix (ECM). Materials and Methods The objective of the present study was to examine the impact of electrospun PLLA nanofiber scaffolds on bone formation in vivo, using a critical size rat calvarial defect model. In addition we analyzed whether direct incorporation of bone morphogenetic protein 2 (BMP-2) into nanofibers could enhance the osteoinductivity of the scaffolds. Two critical size calvarial defects (5 mm) were created in the parietal bones of adult male Sprague-Dawley rats. Defects were either (1) left unfilled, or treated with (2) bovine spongiosa, (3) PLLA scaffolds alone or (4) PLLA/BMP-2 scaffolds. Cranial CT-scans were taken at fixed intervals in vivo. Specimens obtained after euthanasia were processed for histology, histomorphometry and immunostaining (Osteocalcin, BMP-2 and Smad5). Results PLLA scaffolds were well colonized with cells after implantation, but only showed marginal ossification. PLLA/BMP-2 scaffolds showed much better bone regeneration and several ossification foci were observed throughout the defect. PLLA/BMP-2 scaffolds also stimulated significantly faster bone regeneration during the first eight weeks compared to bovine spongiosa. However, no significant differences between these two scaffolds could be observed after twelve weeks. Expression of osteogenic marker proteins in PLLA/BMP-2 scaffolds continuously increased throughout the observation period. After twelve weeks osteocalcin, BMP-2 and Smad5 were all significantly higher in the PLLA/BMP-2 group than in all other groups. Conclusion Electrospun PLLA nanofibers facilitate colonization of bone defects, while their use in combination with BMP-2 also increases bone regeneration in vivo and thus combines osteoconductivity of the scaffold with the ability to maintain an adequate osteogenic stimulus

Synthetic polymer-based membrane for lithium Ion batteries

Efficient energy storage systems are increasingly needed due to advances in portable electronics and transport vehicles, lithium-ion batteries standing out among the most suitable energy storage systems for a large variety of applications. In lithium-ion batteries, the porous separator membrane plays a relevant role as it is placed between the electrodes and serves as a charge transfer medium and affects the cycle behavior. Typically, porous separators membranes are comprised of a synthetic polymeric matrix embedded in the electrolyte solution. The present chapter focus on recent advances in synthetic polymers for porous separation membranes, as well as on the techniques for membrane preparation and physicochemical characterization. The main challenges to improve synthetic polymer performance for battery separator membrane applications are also discussed.Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019, UID/QUI/50006/2019, UID/QUI/0686/2016 and UID/EMS/00151/2019. The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the project PTDC/FIS-MAC/28157/2017, Grants 38 SFRH/BPD/117838/2016 (JNP). and SFRH/BPD/112547/2015 (C.M.C). Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry and Education Departments under the ELKARTEK, HAZITEK and PIBA (PIBA-2018-06

The language in german rap - brutalization or extension of a youth language? : focusing on the artists Haftbefehl & Money Boy

Diese Bachelorarbeit beschäftigt sich mit der Sprache im Deutschrap und es soll die Frage geklärt werden, ob deutsche Rapper Einfluss auf die Sprachentwicklung Jugendlicher nehmen und wenn ja, ob dies zu einer Verrohung oder Erweiterung der Jugendsprache führt. Diese Untersuchung war notwendig, da die Hip-Hop Kultur in der Öffentlichkeit oft kritisiert und mit Sprachverfall in Verbindung gebracht wird. Da die Auswahl an wissenschaftlicher Literatur zu dem Thema „Sprachgebrauch im Deutschrap“ begrenzt ist, wurde vermehrt graue und unselbständig erschienene Literatur, wie Zeitungs- und Blogartikel, Interviews und das Internet zur Untersuchung herangezogen. Das Ergebnis der Arbeit zeigt, dass deutsche Rapper teilweise einen großen Einfluss auf die Sprachentwicklung Jugendlicher nehmen, dies allerdings als eine Erweiterung der Jugendsprache gewertet werden kann, da Veränderungen im Sprachgebrauch ein natürlicher Prozess des Sprachwandels ist und die Jugendsprache einem ständigen Wandel unterzogen ist

Matija Ban and his contribution to the Yugoslav idea, 1844-1862

SIGLEAvailable from British Library Document Supply Centre- DSC:D40436/82 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Multi-criteria analysis of the integration of Solar Thermal Collectors and Borehole Thermal Energy Storage Systems into existing District Heating Grids

Solar district heating (SDH) is a rapidly expanding technology, which can help to replace large amounts of conventionally produced thermal energy by renewable heat. However, the inherent seasonal mismatch of heat demand and solar heat supply reduces its potential substantially. This drawback can be overcome by seasonal thermal energy storage. Due to their large capacities, Borehole Thermal Energy Storage (BTES) systems are particularly suited for district scale solutions. The efficiency of those systems and their components is highly dependent on the implemented operational temperature levels. To quantify those interdependent and partially opposing effects, a numerical case study is carried out, in which a SDH system with BTES is integrated into an existing district heating grid. For this purpose, a coupled numerical simulation approach has been developed, in which the above- and below-ground parts of the system are considered each in dedicated software environments. The BTES is simulated using FEFLOW, a finite-element software tool, taking into account the specific geology of the site under investigation. The SDH is simulated in SimulationX, a system simulation suite based on Modelica, providing detailed information about energy supply, demand and losses of the grid and each component. 16 different scenarios for the grid and storage discharge temperatures are analyzed taking into account energetic, economic and ecological criteria. The results show that optimal solutions can vary considerably according to the weighting of objectives. Furthermore, the study reveals that the optimization of the overall system in a multi-objective approach is much more important than focusing on component efficiencies only. However, the results are highly sensitive to economic boundary conditions. Accordingly, the considered regulatory framework and energy prices are very important