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A German–Brazilian research project investigates sugarcane as an energy plant in anaerobic digestion for biogas production. The aim of the project is a continuous, efficient, and stable biogas process with sugarcane as the substrate. Tests are carried out in a fermenter with a volume of 10 l.
In order to optimize the space–time load to achieve a stable process, a continuous process in laboratory scale has been devised. The daily feed in quantity and the harvest time of the substrate sugarcane has been varied. Analyses of the digester content were conducted twice per week to monitor the process: The ratio of inorganic carbon content to volatile organic acid content (VFA/TAC), the concentration of short-chain fatty acids, the organic dry matter, the pH value, and the total nitrogen, phosphate, and ammonium concentrations were monitored. In addition, the gas quality (the percentages of CO₂, CH₄, and H₂) and the quantity of the produced gas were analyzed.
The investigations have exhibited feasible and economical production of biogas in a continuous process with energy cane as substrate. With a daily feeding rate of 1.68gᵥₛ/l*d the average specific gas formation rate was 0.5 m3/kgᵥₛ. The long-term study demonstrates a surprisingly fast metabolism of short-chain fatty acids. This indicates a stable and less susceptible process compared to other substrates.
A promising approach to reduce the system costs of molten salt solar receivers is to enable the irradiation of the absorber tubes on both sides. The star design is an innovative receiver design, pursuing this approach. The unconventional design leads to new challenges in controlling the system. This paper presents a control concept for a molten salt receiver system in star design. The control parameters are optimized in a defined test cycle by minimizing a cost function. The control concept is tested in realistic cloud passage scenarios based on real weather data. During these tests, the control system showed no sign of unstable behavior, but to perform sufficiently in every scenario further research and development like integrating Model Predictive Controls (MPCs) need to be done. The presented concept is a starting point to do so.
Control of Aharonov-Bohm oscillations in a AlGaAs/GaAs ring by asymmetric and symmetric gate biasing
(2001)
Reinforced concrete (RC) frames with masonry infills are frequently used in seismic regions all over the world. Generally masonry infills are considered as nonstructural elements and thus are typically neglected in the design process. However, the observations made after strong earthquakes have shown that masonry infills can modify the dynamic behavior of the structure significantly. The consequences were total collapses of buildings and loss of human lives. This paper presents the new system INODIS (Innovative Decoupled Infill System) developed within the European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in RC Buildings). INODIS decouples the frame and the masonry infill by means of special U-shaped rubbers placed in between frame and infill. The effectiveness of the system was investigated by means of full scale tests on RC frames with masonry infills subjected to in-plane and out-of-plane loading. Furthermore small specimen tests were conducted to determine material characteristics of the components and the resistances of the connections. Finally, a micromodel was developed to simulate the in-plane behavior of RC frames infilled with AAC blocks with and without installation of the INODIS system.
The increasing share of renewable electricity in the grid drives the need for sufficient storage capacity. Especially for seasonal storage, power-to-gas can be a promising approach. Biologically produced methane from hydrogen produced from surplus electricity can be used to substitute natural gas in the existing infrastructure. Current reactor types are not or are poorly optimized for flexible methanation. Therefore, this work proposes a new reactor type with a plug flow reactor (PFR) design. Simulations in COMSOL Multiphysics ® showed promising properties for operation in laminar flow. An experiment was conducted to support the simulation results and to determine the gas fraction of the novel reactor, which was measured to be 29%. Based on these simulations and experimental results, the reactor was constructed as a 14 m long, 50 mm diameter tube with a meandering orientation. Data processing was established, and a step experiment was performed. In addition, a kLa of 1 h−1 was determined. The results revealed that the experimental outcomes of the type of flow and gas fractions are in line with the theoretical simulation. The new design shows promising properties for flexible methanation and will be tested.
Producing fresh water from saline water has become one of the most difficult challenges to overcome especially with the high demand and shortage of fresh water. In this context, as part of a collaboration with Germany, the authors propose a design and implementation of a pilot multi-stage solar desalination system (MSD), remotely controlled, at Douar Al Hamri in the rural town of Boughriba in the province of Berkane, Morocco. More specifically, they present their contribution on the remote control and supervision system, which makes the functioning of the MSD system reliable and guarantees the production of drinking water for the population of Douar. The results obtained show that the electronic cards and computer communication software implemented allow the acquisition of all electrical (currents, voltages, powers, yields), thermal (temperatures of each stage), and meteorological (irradiance and ambient temperature), remote control and maintenance (switching on, off, data transfer). By comparing with the literature carried out in the field of solar energy, the authors conclude that the MSD and electronic desalination systems realized during this work represent a contribution in terms of the reliability and durability of providing drinking water in rural and urban areas.
The Solar-Institut Jülich (SIJ) and the companies Hilger GmbH and Heliokon GmbH from Germany have developed a small-scale cost-effective heliostat, called “micro heliostat”. Micro heliostats can be deployed in small-scale concentrated solar power (CSP) plants to concentrate the sun's radiation for electricity generation, space or domestic water heating or industrial process heat. In contrast to conventional heliostats, the special feature of a micro heliostat is that it consists of dozens of parallel-moving, interconnected, rotatable mirror facets. The mirror facets array is fixed inside a box-shaped module and is protected from weathering and wind forces by a transparent glass cover. The choice of the building materials for the box, tracking mechanism and mirrors is largely dependent on the selected production process and the intended application of the micro heliostat. Special attention was paid to the material of the tracking mechanism as this has a direct influence on the accuracy of the micro heliostat. The choice of materials for the mirror support structure and the tracking mechanism is made in favor of plastic molded parts. A qualification assessment method has been developed by the SIJ in which a 3D laser scanner is used in combination with a coordinate measuring machine (CMM). For the validation of this assessment method, a single mirror facet was scanned and the slope deviation was computed.
IEC Technical Committee 81 is currently creating the new IEC 62305 series of standards on Lightning Protection. Working Group 9 is responsible for Part 2 of this series, which deals with the assessment and management of risk its CDV (Committee Draft for Voting) stage and has been circulated to National Committees for comment. The paper details the development of the Simplified IEC Risk Assessment Calculator software tool as described in Informative Annex J of IEC62305-2 Ed.1/CDV 2. This tool is intended as a simplified implementation of the more rigorous treatment of risk management found in the written document. It is designed to be relatively intuitive for users who wish to obtain an initial assessment of risk sensitivity, but should not be considered a substitute to a full understanding of the methods provided in the standard when dealing with more complicated structures or those where greater risks to personal or system operation are involved.
In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed.
In this work, three patent pending calibration methods for heliostat fields of central receiver systems (CRS) developed by the Solar-Institut Jülich (SIJ) of the FH Aachen University of Applied Sciences are presented. The calibration methods can either operate in a combined mode or in stand-alone mode. The first calibration method, method A, foresees that a camera matrix is placed into the receiver plane where it is subjected to concentrated solar irradiance during a measurement process. The second calibration method, method B, uses an unmanned aerial vehicle (UAV) such as a quadrocopter to automatically fly into the reflected solar irradiance cross-section of one or more heliostats (two variants of method B were tested). The third calibration method, method C, foresees a stereo central camera or multiple stereo cameras installed e.g. on the solar tower whereby the orientations of the heliostats are calculated from the location detection of spherical red markers attached to the heliostats. The most accurate method is method A which has a mean accuracy of 0.17 mrad. The mean accuracy of method B variant 1 is 1.36 mrad and of variant 2 is 1.73 mrad. Method C has a mean accuracy of 15.07 mrad. For method B there is great potential regarding improving the measurement accuracy. For method C the collected data was not sufficient for determining whether or not there is potential for improving the accuracy.
Development of open educational resources for renewable energy and the energy transition process
(2021)
The dissemination of knowledge about renewable energies is understood as a social task with the highest topicality. The transfer of teaching content on renewable energies into digital open educational resources offers the opportunity to significantly accelerate the implementation of the energy transition. Thus, in the here presented project six German universities create open educational resources for the energy transition. These materials are available to the public on the internet under a free license. So far there has been no publicly accessible, editable media that cover entire learning units about renewable energies extensively and in high technical quality. Thus, in this project, the content that remains up-to-date for a longer period is appropriately prepared in terms of media didactics. The materials enable lecturers to provide students with in-depth training about technologies for the energy transition. In a particular way, the created material is also suitable for making the general public knowledgeable about the energy transition with scientifically based material.
We study the possibility to fabricate an arbitrary phase mask in a one-step laser-writing process inside the volume of an optical glass substrate. We derive the phase mask from a Gerchberg–Saxton-type algorithm as an array and create each individual phase shift using a refractive index modification of variable axial length. We realize the variable axial length by superimposing refractive index modifications induced by an ultra-short pulsed laser at different focusing depth. Each single modification is created by applying 1000 pulses with 15 μJ pulse energy at 100 kHz to a fixed spot of 25 μm diameter and the focus is then shifted axially in steps of 10 μm. With several proof-of-principle examples, we show the feasibility of our method. In particular, we identify the induced refractive index change to about a value of Δn=1.5⋅10−3. We also determine our current limitations by calculating the overlap in the form of a scalar product and we discuss possible future improvements.
Engineers and therefore engineering education are challenged by the increasing complexity of questions to be answered globally. The education of future engineers therefore has to answer with curriculums that build up relevant skills. This chapter will give an example how to bring engineering and social responsibility successful together to build engineers of tomorrow. Through the integration of gender and diversity perspectives, engineering research and teaching is expanded with new perspectives and contents providing an important potential for innovation. Aiming on the enhancement of engineering education with distinctive competencies beyond technical expertise, the teaching approach introduced in the chapter represents key factors to ensure that coming generations of engineers will be able to meet the requirements and challenges a changing globalized world holds for them. The chapter will describe how this approach successfully has been implemented in the curriculum in engineering of a leading technical university in Germany.
Contemporary research appreciates a diverse workforce as a potential source of innovation. Researchers explore the fine details of why diversity management is central for generating innovations in heterogeneous research groups and how it could be effectively implemented into organizations. Complex research associations that discuss topics with a high impact on society increasingly address the necessity of establishing a diverse workforce to confront the challenges of tomorrow. Characterized by complex management structures as well as hierarchies, research associations have not been a subject of investigation until now. For this reason, the presented research project aims to develop a diversity and innovation management strategy with the ultimate goal of inducing change in the corporate culture. The proposed approach consisted of six phases; the first two phases investigated the status quo of diversity in the existing organizational structures of member institutes and the variety of particular working cultures within the research association. The third and the fourth phases utilized qualitative and quantitative studies. The third phase focused on the connection of management level to diversity and innovation, and the need for diversity and innovation management, and tailor-made methods of implementing them. The first three phases have been accomplished successfully; preliminary results are already available. The fourth phase will mainly focus on exploring the mind-set of the employees. The fifth phase will consolidate the findings in the first four phases into an implementable strategy. The final phase will address the implementation of this strategy into the organization. Phases 4 to 6 have not yet been undertaken
Insbesondere im wirtschaftlichen Kontext wird die Diversität von Belegschaften zunehmend als ein kritischer Erfolgsfaktor gesehen. Neben dem Potenzial, welches sich laut Studien aus einem vielfältigen Team ergibt, werden jedoch ebenfalls die aus menschlicher Diversität resultierenden Herausforderungen thematisiert und wissenschaftlich untersucht. Sowohl aus dem Potenzial als auch aus den Herausforderungen ergibt sich dabei die Notwendigkeit der Implementierung eines organisationsspezifischen Diversity Managements, welches die Gewinnung neuer Mitarbeiter*innen einerseits und das Management der vorhandenen Vielfalt andererseits gleichermaßen unterstützt. In der psychologischen, sozial- und wirtschaftswissenschaftlichen Literatur gibt es unterschiedliche Definitionen von Diversität, woraus sich verschiedene Perspektiven auf das Vorgehen bei der Gestaltung und Umsetzung eines Diversity Management Ansatzes ergeben. Insbesondere vor dem Hintergrund der Komplexität des Organisationsumfeldes und der steigenden Anforderungen an die organisationsinterne Agilität besteht die Notwendigkeit, Diversität in Organisationen stärker zu reflektieren und systemspezifische Ansätze zu entwickeln. Dies erfordert die Berücksichtigung organisationsspezifischer Strukturen und Prozesse sowie die Reflexion des Wandels der Organisationskultur durch die Umsetzung eines Diversity Management Ansatzes, der die gegebene Komplexität aufgreift und bewältigen kann. Darüber hinaus sind die psychologischen Auswirkungen solcher Veränderungen auf die Mitarbeiter*innen zu berücksichtigen, um Reaktanzen zu vermeiden und eine nachhaltige Umsetzung von Diversity Management zu ermöglichen. In Ermangelung entsprechender Ansätze im Rahmen öffentlich finanzierter, komplexer Forschungsorganisationen, ist das Ziel dieser Dissertation die Entwicklung und Erprobung eines Forschungsdesigns, welches die Ansätze des Diversity- und Change Managements mit der Organisationskultur verknüpft, indem es eine systemtheoretische Perspektive einnimmt. Dabei wird das Forschungsdesign auf eine komplexe wissenschaftliche Organisation angewendet. Als Basis dient die in Teil A durchgeführte Betrachtung des aktuellen Forschungsstandes aus einer interdisziplinären Perspektive und die damit einhergehende umfassende Einführung in das Forschungsfeld. Im Zuge dessen wird detailliert auf die begriffliche Definition von Diversität eingegangen, bevor dann die psychologischen Konzepte im Diversitätskontext den Übergang zu einer differenzierten Auseinandersetzung mit dem Konzept des Diversity Managements bilden. Auf dieser Grundlage werden das Forschungsdesign sowie die daraus resultierenden Forschungsphasen abgeleitet. Teil A stellt somit die theoretische Grundlage für die in Teil B präsentierten Fachaufsätze dar. Jeder Fachaufsatz beleuchtet dabei in chronologischer Reihenfolge die unterschiedlichen Forschungsphasen. Fachaufsatz I präsentiert den sechsstufigen Forschungsansatz und beleuchtet die besonderen Rahmenbedingungen des Forschungsobjektes aus einer theoretischen Perspektive. Im Anschluss werden die Ergebnisse der Organisationsanalyse, welche zugleich Phase I und II des Forschungskonzeptes darstellen, vorgestellt. Aufbauend auf diesen Forschungsergebnissen fokussiert Forschungsaufsatz II die Darlegung der Ergebnisse aus Forschungsphase III, der Befragung der Führungsebene. Die Befragung thematisierte dabei die Wahrnehmung von Diversity und Diversity Management auf Führungsebene, die Verknüpfung von Diversität mit Innovation sowie die Reflexion des eigenen Führungsstils. Als Ergebnis der Befragung konnten sechs Typen identifiziert werden, die das Führungsverständnis im Diversitätskontext widerspiegeln und somit den Ansatzpunkt für eine top-down gerichtete Diversity Management Strategie darstellen. Darauf aufbauend wird in Forschungsphase IV die Mitarbeiter*innenebene beforscht. Im Zentrum der quantitativen Befragung standen die vorherrschenden Einstellungen zum Themenkomplex Diversity und Diversity Management, die Wahrnehmung von Diversität sowie die Untersuchung des Einflusses der Führungsebene auf die Mitarbeiter*innenebene. Forschungsaufsatz III präsentiert erste Ergebnisse dieser Untersuchung. Die Analyse weist auf eine unterschiedliche Gewichtung der verschiedenen Diversitätskategorien hinsichtlich der Verknüpfung mit Innovationen und somit der Reflexion des Kontextes zwischen Diversität und Innovationen hin. Vergleichbar mit den identifizierten Typen auf der Führungsebene, deutet die Analyse auf die Existenz unterschiedlicher Reflexionsgrade auf Mitarbeiter*innenebene hin. Auf Basis dessen wird im Rahmen von Forschungsaufsatz IV eine nähere Untersuchung des Reflexionsgrades auf Mitarbeiter*innenebene präsentiert und der Diversity Management Ansatz mit Elementen des Change Managements kombiniert. Besondere Berücksichtigung findet als Schlussfolgerung einer theoretischen Analyse die Organisationskultur als zentrales Element bei der Entwicklung und Einführung eines Diversity Management Ansatzes in eine komplexe Forschungsorganisation in Deutschland. Die Analyse zeigt, dass die Wahrnehmung von Diversität heterogen aber zunächst losgelöst vom individuellen Hintergrund ist (im Rahmen dieser Analyse lag der Fokus auf den Diversitätskategorien Gender und Herkunft). Hinsichtlich der Wertschätzung von Diversität zeigt sich dabei ebenfalls ein heterogenes Bild. In der Gesamtbetrachtung stimmen lediglich 17% der Mitarbeiter*innen zu, dass Diversitätskategorien wie Gender, Herkunft oder auch Alter einen Mehrwert darstellen können. Zugleich bewertet diese Gruppe die dem Thema beigemessene Wichtigkeit im CoE als ausreichend. Zusammengefasst lassen sich folgende Erkenntnisse im Rahmen dieser Dissertation ableiten und dienen somit als Grundlage für die Entwicklung eines Diversity Management Ansatzes: (1) Die Entwicklung eines bedarfsorientierten Diversity Management Ansatzes erfordert einen systemtheoretischen Prozess, der sowohl organisationsinterne als auch externe Einflussfaktoren berücksichtigt. Der im Rahmen des Forschungsprojektes entwickelte sechsstufige Forschungsprozess hat sich dabei als geeignetes Instrument erwiesen. (2)Im Rahmen öffentlicher Forschungseinrichtungen lassen sich dabei drei zentrale Faktoren identifizieren: die individuelle Reflexionsebene, die Organisationskultur sowie extern beeinflusste Organisationsstrukturen, Prozesse und Systeme.(3)Vergleichbar mit privatwirtschaftlichen Unternehmen hat auch in wissenschaftlichen Organisationen die Führungsebene einen maßgeblichen Einfluss auf die Wahrnehmung von Diversität und somit einen Einfluss auf die Umsetzung einer Diversity Management Strategie. Daher ist auch im wissenschaftlichen Kontext, bedingt durch die rechtlichen Rahmenbedingungen des Hochschulsystems, ein top-down Ansatz für eine nachhaltige Implementierung erforderlich. (4) Diversity Management steht in einem engen Zusammenhang mit einem organisationalen Wandel, was die Reflexion von Veränderungsprozesse aus einer psychologischen Perspektive erfordert und eine Verknüpfung von Diversity und Change Management bedingt. Aufbauend auf den im Rahmen des entwickelten Forschungskonzeptes gewonnenen zentralen Erkenntnissen wird ein Ansatz entwickelt, der die Ableitung theoretischer Implikationen sowie Implikationen für das Management ermöglicht. Insbesondere vor dem Hintergrund der Reflexion der besonderen Rahmenbedingungen öffentlich finanzierter Forschungsorganisationen werden darüber hinaus politische Implikationen abgeleitet, die auf die Veränderung struktureller Dimensionen abzielen.
Diversity is increasingly being addressed as an innovation-promoting factor. For this reason, companies and institutions tackle the integration of a diversity management approach that enables a heterogenic perspective on innovation development. However, system-theoretical frameworks state that the implementation of diversity measures that are not tailored to the needs of the organization often leads to a rejection or reactivity with regard to the management approach. In this context, especially organizations, which are characterized by a specific hierarchical structure, a dominant habitus or specialist culture, must face the challenge of realizing a sustainable change of the corporate culture that sets the basis for implementing diversity management approaches. The presented research project focuses on analyzing the situation in a huge scientific collaborative project - so called Cluster of Excellence (CoE) - with the aim to implement a diversity - and innovation management strategy. Considering the influencing determinants, the CoE is characterized by its embeddedness in the scientific system, a complex organizational structure, and a high fluctuation rate. The paper presents a systemic approach of reflecting these factors in order to develop a diversity- and innovation management strategy. In this frame, the results of a quantitative survey of CoE employees and derived mindset-types are presented. The results show a need for taking different mindset-types into account, to be able to develop a tailored management strategy. The aim of the project is to give recommendations for developing a sustainable management concept that promotes both diversity and innovation by drawing on the persisting mindsets of organization members while reflecting top down as well as bottom up factors of implementation processes as well as the psychology of change. This paper addresses all who are concerned with the management of human resources in innovation processes and are striving for a cultural change within the framework of complex organizations.
This work presents a basic forecast tool for predicting direct normal irradiance (DNI) in hourly resolution, which the Solar-Institut Jülich (SIJ) is developing within a research project. The DNI forecast data shall be used for a parabolic trough collector (PTC) system with a concrete thermal energy storage (C-TES) located at the company KEAN Soft Drinks Ltd in Limassol, Cyprus. On a daily basis, 24-hour DNI prediction data in hourly resolution shall be automatically produced using free or very low-cost weather forecast data as input. The purpose of the DNI forecast tool is to automatically transfer the DNI forecast data on a daily basis to a main control unit (MCU). The MCU automatically makes a smart decision on the operation mode of the PTC system such as steam production mode and/or C-TES charging mode. The DNI forecast tool was evaluated using historical data of measured DNI from an on-site weather station, which was compared to the DNI forecast data. The DNI forecast tool was tested using data from 56 days between January and March 2022, which included days with a strong variation in DNI due to cloud passages. For the evaluation of the DNI forecast reliability, three categories were created and the forecast data was sorted accordingly. The result was that the DNI forecast tool has a reliability of 71.4 % based on the tested days. The result fulfils SIJ’s aim to achieve a reliability of around 70 %, but SIJ aims to still improve the DNI forecast quality.