Technische Universitat Berlin Research Articles

INSYSTED – An Open-Source Platform for Blended Learning Based on Serious Games in Operations Management

Operations management is a quantitative core area of Industrial Engineering and Management education where students need to tackle the stochastic-dynamic interdependencies of processes within a supply network. In order to do so, students need to acquire a deep understanding of the underlying theortical concepts, methods, and tools. This is especially challenging for students at an introductory level. The heterogeneous knowledge and interests as well as the sheer number of participants in typical introductory courses urgently require new solutions for personalized learning. Against this background, the serious game ProTUce was developed at Technische Universitat Berlin. Here, problem-oriented, quantitative methods of operations management are taught – using a virtual learning factory. In subsequent game levels, students are confronted with different challenges of everyday production based on the progress of the course, experience system dynamics, and improve their analytical skills. ProTUce is built on the open-source platform INSYSTED (Integrated System for European Digital Learning), which is currently being developed in a consortium of Technische Universitat Berlin, University College London, Politecnico di Milano, and CentraleSupelec in Paris. The INSYSTED platform supports lecturers in creating, playing, and sharing serious games. In this paper, we introduce the INSYSTED framework and illustrate its application, using the serious game ProTUce.

From TechnoSat to TUBIN: performance upgrade for the TUBiX20 microsatellite platform based on flight experience

On July 14th, 2017, the 20 kg satellite TechnoSat was carried into orbit from Baikonur Cosmodrome as the first satellite based on Technische Universitat Berlin’s novel modular TUBiX20 microsatellite platform. Its mission is the in-orbit demonstration of the platform and seven additional payloads. The second mission based on TUBiX20 is TUBIN, which is scheduled for launch in 2020. The satellite carries two infrared imagers accompanied by a camera for the visible light spectrum and shall demonstrate wildfire detection from orbit. While the platform concept already proved itself successful during TechnoSat operations, its performance needs to be further enhanced for TUBIN to meet the requirements of its Earth observation payload. This paper describes the upgrade of the TUBiX20 platform according to the requirements of the TUBIN mission. Here, the focus is set on illustrating how the modular platform design allows scaling the performance while at the same time keeping the modifications to the flight-proven system at a minimum. Second, the paper gives insights into the results of the TechnoSat mission and outlines how the experience gained in orbit benefits the platform upgrade for TUBIN.

On viscous gradient fluids

A framework for linear viscous gradient fluids as extensions of the Navier–Stokes law is derived. More precisely, the list of the independent variables is enlarged up to an Nth-order velocity gradient and, accordingly, also the list of the dependent variables up to dual hyperstress tensors of the same rank. It is shown that due to general invariance requirements, such models must be hemitropic functions. A complete representation for a second-order linear fluid and its balance equation are derived from a dissipation potential. In doing so, we follow Trostel (in: Trostel (ed) Beitrage zu den Ingenieurwissenschaften, Universitats-Bibliothek der Technische Universitat Berlin, Berlin, 96–134, 1985) and coworkers.

Hormigón infraligero: Listo para la práctica (English version)

Hormigón infraligero: después de diez años de investigación en la Technische Universität Berlin (TU Berlin) y tras la construcción de una vivienda piloto hace diez años como prueba de la eficacia de este innovador material, el hormigón infraligero está listo para la práctica. Los riesgos implicados que toda innovación lleva consigo son ahora previsibles. Para aquellos que quieran usar este hormigón estructural de alto rendimiento o investigarlo más a fondo, encontrarán en este artículo un resumen de lo más importante acerca de este material, el cual permite estructuras de hormigón visto que prácticamente no necesitan ninguna medida adicional de aislamiento térmico. Los resultados alcanzados hasta ahora por los autores y la investigación en curso son presentados en detalle. El diseño estructural apropiado con este material y su potencial de forma serán también discutidos, así como los requisitos necesarios para su aprobación, ya que su uso no está cubierto por los Eurocódigos. Finalmente, se presentan algunos edificios de hormigón infraligero construidos hasta ahora y otros que están siendo actualmente planificados.

Analysis of moving model experiments in a towing tank for aerodynamic drag measurement of high-speed trains

The present study assesses the applicability of towing tank experiments using a moving model for the investigation of the aerodynamics of long land-borne heavy vehicles such as buses, trucks, and trains. Based on experiments with a 1:22 scaled model of a high-speed train, the influence of various conditions relevant for the transferability of the results obtained in water to air is analysed exemplarily. These conditions include surface waves, cavitation and submergence depth. The experiments were carried out in the shallow water towing tank of the Technische Universitat Berlin. It is shown that outside a critical Froude number range of about 0.2 < Fr < 1.2 the impact of the surface waves can be neglected and no cavitation appears in the velocity range investigated. Furthermore, a correction method is proposed taking into account the bias through surface waves at small submergence and thus allowing for a wider Froude number range. The data obtained in the towing tank are found to be in excellent agreement to other investigation methods.

Applying robotic frameworks in a simulated multi-agent contest

In the Multi-Agent Programming Contest 2017 the TUBDAI team of the Technische Universitat Berlin is using the complex multi-agent scenario to evaluate the application of two frameworks from the field (multi-)robot systems. In particular the task-level decision-making and planning framework ROS Hybrid Behaviour Planner (RHBP) is used to implement the execution and decision-making for single agents. The RHBP framework builds on top of the framework Robot Operating System (ROS) that is used to implement the communication and scenario specific coordination strategy of the agents. The united team for the official contest is formed by volunteering students from a project course and their supervisors.

Multi-Modal Active Vibration Control of a Lightweight Stress-Ribbon Footbridge Based on Subspace Identification

Abstract Experimental identification of the modal state-space model for Active Vibration Control (AVC) is proposed based on Subspace Identification Method (SIM). A stress-ribbon bridge built at the Technische Universitat Berlin was taken as research object. A real-time control system with pneumatic muscle actuators and inertial sensors was set up for AVC of the bridge. For the purpose of AVC, the feedback control design requires a modal state-space model, which describes the multi-modal characteristics of resonance modes of the bridge and the input/output relationship of the controlled system. Analytically, a state-space model of the bridge can be derived from Euler-Lagrange mechanism. However this is computationally expensive and the determination of damping ratios is also inconvenient. Comparably, SIM offers an attractive alternative due to simple and general parametrisation for Multiple-Input Multiple-Output (MIMO) systems. The identified state-space model from SIM can easily be transformed into a reduced modal state-space model for the AVC controller design. The goodness of the identified state-space model and the truncated modal state-space model was investigated in the stabilization diagram of SIM and with model fit indexes. The identified modal parameters of the footbridge from SIM were compared with that of previous free-vibration tests and the analytical model. Implementation of a Delayed Modal Velocity Feedback Control (DMVFC) based on the obtained modal state-space model was carried out for the full-scale lightweight bridge. The effectiveness of the proposed experimental identification method was shown in case of vertical resonance modes in vibration control experiments.

Solutions for Sustainable Machining

The manufacturing industry contributes over 19% to the world's greenhouse gas emissions (U.S. Energy Information Administration, 2008, “Rep: Annual Energy Review 2008,” Report No. DOE/EIA-0384; Diaz et al., 2010, “Environmental Analysis of Milling Machine Tool Use in Various Manufacturing Environments,” 2010 IEEE International Symposium on Sustainable Systems and Technology.) and 31% of the total energy consumed annually in the U.S. (Herzog, T., 2005, “World Greenhouse Gas Emissions in 2005,” World Resources Institute, Washington, DC 2; Diaz et al., 2010, “Environmental Analysis of Milling Machine Tool Use in Various Manufacturing Environments,” 2010 IEEE International Symposium on Sustainable Systems and Technology.). There is therefore an increasing demand for sustainable solutions for the production technology industry. At the Technische Universitat (TU) Berlin, Germany, a collaborative research center (CRC) is focusing on new solutions for the sustainable machining of high performance alloys, with developments from machine tool frames to cutting tool technology being undertaken. An innovative machine tool concept with a modular frame, which allows a high level of flexibility, has been developed. Furthermore, add-on upgrading systems for older machine tools, which are particularly relevant for developing countries, have been developed. These systems allow the accuracy of outdated machine tools to be increased, thus making the machine tools comparable to modern systems. Finally the cutting process also requires solutions for dry machining, as the use of cooling lubricant is environmentally damaging and a significant cost contributor in machining processes. Two solutions are being developed at the TU Berlin: an internally cooled cutting tool and a heating concept for ceramic tools to allow dry machining of high temperature alloys, for example, for the aerospace industry.

The TUBIN nanosatellite mission for wildfire detection in thermal infrared

The increasing number of wildfires has significant impact on the Earth’s climate system. Furthermore, they cause severe economic damage in many parts of the world. While different land and airborne wildfire detection and observation systems are in use in some areas of the world already, spaceborne systems offer great potential regarding global and continuous observation. TUBIN is a proof-of-concept mission to demonstrate the capabilities of a nanosatellite carrying lightweight infrared microbolometer arrays for spaceborne detection of wildfires and other high-temperature events. To this end, TUBIN carries two infrared microbolometers complemented by a CMOS imager. The TUBIN space segment is based on the TUBiX20 nanosatellite platform of Technische Universitat Berlin and is the first mission that implements the full-scale attitude determination and control system of TUBiX20. Thereby, the TUBIN mission will demonstrate the platform’s ability to support a challenging Earth observation mission.

Accelerometer-based estimation and modal velocity feedback vibration control of a stress-ribbon bridge with pneumatic muscles

Lightweight footbridges are very elegant but also prone to vibration. By employing active vibration control, smart footbridges could accomplish not only the architectural concept but also the required serviceability and comfort. Inertial sensors such as accelerometers allow the estimation of nodal velocities and displacements. A Kalman filter together with a band-limited multiple Fourier linear combiner (BMFLC) is applied to enable a drift-free estimation of these signals for the quasi-periodic motion under pedestrian excitation without extra information from other kinds of auxiliary sensors. The modal velocities of the structure are determined by using a second Kalman filter with the known applied actuator forces as inputs and the estimated nodal displacement and velocities as measurements. The obtained multi-modal velocities are then used for feedback control. An ultra-lightweight stress-ribbon footbridge built in the Peter-Behrens- Halle at the Technische Universitat Berlin served as the research object. Using two inertial sensors in optimal points we can estimate the dominant modal characteristics of this bridge. Real-time implementation and evaluation results of the proposed estimator will be presented in comparison to signals derived from classical displacement encoders. The real-time estimated modal velocities were applied in a multi-modal velocity feedback vibration control scheme with lightweight pneumatic muscle actuators. Experimental results demonstrate the feasibility of using inertial sensors for active vibration control of lightweight footbridges.

Hydroformylation in Microemulsions: Proof of Concept in a Miniplant

The implementation of the hydroformylation reaction for the conversion of long-chain alkenes into aldehydes still remains challenging on an industrial scale. One possible approach to overcoming this challenge is to apply tunable systems employing surfactants. Therefore, a novel process concept for the hydroformylation of long-chain alkenes to aldehydes in microemulsions is being investigated and developed at Technische Universitat Berlin, Germany. To test the applicability of this concept for the hydroformylation in microemulsions on a larger scale, a miniplant has been constructed and operated. This contribution presents the proof of concept for hydroformylation in microemulsions carried out during a 200 h miniplant operation. Throughout the operation a stable aldehyde yield of 21% and a catalyst loss in the product phase below 0.1 ppm were achieved, which confirms previous lab scale findings. Additionally, solution strategies for a stable continuous operation to overcome challenges such as foaming, phas...

A common approach to intelligent energy and mobility services in a smart city environment

Due to the fact that electric vehicles have not broadly entered the vehicle market there are many attempts to convince producers to integrate technologies that utilise embedded batteries for purposes different from driving. The vehicle-to-grid technology, for instance, literally turns electric vehicles into a mobile battery, enabling new areas of applications (e.g., to provide regulatory energy, to do grid-load balancing, or to buffer surpluses of energy) and business perspectives. Utilising a vehicle’s battery, however is not without a price—in this case: the driver’s mobility. Given this dependency, it is interesting that most available works consider the application of electric vehicles for energy and grid-related problems in isolation, that is, detached from mobility-related issues. The distributed artificial intelligence laboratory, or DAI-Lab, is a third-party funded research lab at Technische Universitat Berlin and integrates the chair for agent technologies in business applications and telecommunication. The DAI-Lab has engaged in a large number of both, past and upcoming projects concerned with two aspects of managing electric vehicles, namely: energy and mobility. This article aims to summarise experiences that were collected during the last years and to present developed solutions which consider energy and mobility-related problems jointly.

CFD Simulation of the Fluid Hydrodynamics in a Continuous Stirred-Tank Reactor

Continuous stirred-tank reactors (CSTR) are widely applied in the chemical, food, and pharmaceutical engineering fields. The micro-scale fluid dynamics are important for the optimal processing study since they have a dominating influence on the overall performance of the reactor. In this article, 3-dimensional Computational Fluid Dynamics (CFD) simulations are carried out to portray the flow characters in the CSTR of the mini-plant of the Collaborative Research Center InPROMPT coordinated by the Technische Universitat Berlin. In InPROMPT, the reactor is used to perform a rhodium-catalyzed hydroformylation of long chain alkenes. In this study, cases of a vessel with and without baffles are compared. The results show the existence of a high speed velocity toroidal zone in different horizontal sections in the CSTR without baffles, comparing to the common pervasive conception which is the assumption of a complete uniformity of the fluid velocity magnitude in a CSTR at the final steady state. Moreover, under the rotation speed of 400 rpm, the baffles in the CSTR can significantly prevent the formation of a surface vortex, for the mean tangential velocity magnitude is dramatically decreased. On the other hand, the mean radial and axial velocity is tremendously increased when the baffles are added. Therefore, the baffles in the tank lead to a greater vertical fluid exchange in CSTR. Besides, in the specific domain of CSTR region, both the fluid velocity direction and magnitude carry on a cyclical variation, when the baffles are inserted into the CSTR.

Analysing sewage handling problems

Some sewage pump stations have to be disassembled and repaired repeatedly. Recently, the Technische Universität Berlin undertook an on-site situation analysis and statistical evaluation of more than 1000 malfunctions from 46 pump stations in Berlin. This became a first step for understanding the major failure causes.

Process Design for the Separation of Three Liquid Phases for a Continuous Hydroformylation Process in a Miniplant Scale

Within the framework of the Collaborative Research Centre SFB/TR 63 InPROMPT, “Integrated chemical processes in liquid multiphase systems”, a novel process concept for the hydroformylation of long chain alkenes to aldehydes in microemulsions is investigated and developed at the Berlin Institute of Technology (Technische Universitat Berlin), Germany. To start the hydroformylation reaction, a hydrophilic rhodium-ligand-complex is required. By applying a nonionic surfactant, a microemulsion system is formed and thus the hydrophilic catalyst is transported into the hydrophobic alkene phase. Next to achieve a high conversion rate in the continuously stirred tank reactor, the separation of the valuable rhodium catalyst from the product phase poses a challenge. This separation is the crucial step for the technical and economic feasibility of the overall process concept and plant design. Owing to the lack of thermodynamic data for microemulsion mixtures, the design of the phase separation unit strongly depends on...

Special issue on recent trends in discrete event systems

This special issue of DEDS on Recent Trends in Discrete Event Systems was inspired by the 10th International Workshop on Discrete Event Systems (WODES 2010), which was held on the campus of Technische Universitat Berlin from 30 August to 1 September 2010. The Workshop Series on Discrete Event Systems started in 1992. Since then workshops have been held every two years: in Prague (1992), Antibes (1994), Edinburgh (1996), Cagliari (1998), Ghent (2000), Zaragoza (2002), Reims (2004), Ann Arbor (2006), Goteborg (2008) and Berlin (2010). Since its inception, WODES has been one of the most influential series of international meetings devoted to various aspects of discrete event systems. The WODES 2010 program included three invited lectures by Paulo Tabuada (UCLA), Rene Boel (Ghent University), and Rajeev Alur (University of Pennsylvania). It also included 50 regular and 22 invited papers selected from a total of 103 submissions. The proceedings of WODES 2010 have been published by IFAC, the International Federation of Automatic Control, and are available online at http://www.ifac-papersonline.net. Following WODES 2010, we were invited by the editorial board of this journal and the WODES steering committee to prepare a special issue of DEDS highlighting

Holocaust Denial: Anti-Semitism as a Refusal to Accept Reality

no abstract

Ionothermal Route to Layered Two-Dimensional Polymer-Frameworks Based on Heptazine Linkers

Technische Universitat Berlin, Funktionsmaterialien, Englische Strasse 20,€10587 Berlin, GermanyReceived May 7, 2010; Revised Manuscript Received July 14, 2010IntroductionLayeredtwo-dimensionalpolymer-frameworksarefascinatingresearch targets. The development of reliable synthetic routes toperiodic, covalent molecular layers touches on structural, analy-tical,technologicalandtheoreticalaspectsofthenaturalsciencesand has a profound impact on fundamental research and itsrealization, as seen for example in graphene research

The Glut of Academic Publishing: A Call for a New Culture

Stanley W. Trimble is professor of geography at the University of California at Los Angeles, Los Angeles, CA 90095-1524; trimble@geog.ucla.edu. He is the co-author with Andy D. Ward of Environmental Hydrology, 2nd ed. (CRC Press, 2004) and editor of The Dekker Encyclopedia of Water Science (CRC Press, 2008). From 1996 to 2006 he was joint editor-in-chief of the Elsevier journal Catena. He is presently writing an environmental history of the upper Midwest. Wayne W. Grody, M.D., Ph.D., is Professor of Pathology & Laboratory Medicine, Pediatrics, and Human Genetics at the David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7035; wgrody@mednet.ucla.edu. He is the director of the Diagnostic Molecular Pathology Laboratory within the UCLA Medical Center, one of the country’s first facilities to offer DNA-based tests for diagnosis of a variety of genetic, infectious, and neoplastic diseases. He is an attending physician in the Department of Pediatrics specializing in the care of patients with or at risk for genetic disorders. He has been one of the primary developers of quality assurance and ethical guidelines for DNA-based genetic testing for a number of governmental and professional agencies. Bill McKelvey is Professor of Strategic Organizing and Complexity Science at the UCLA Anderson School of Management, Los Angeles, CA 90095-1481; mckelvey@anderson.ucla.edu. His Organizational Systematics (University of California Press, 1982) remains the definitive treatment of organizational taxonomy and evolution. He is co-editor, with Peter Allan and Steve Maguire, of the Sage Handbook of Complexity and Management (Sage, 2010). Mohamed Gad-el-Hak has taught and conducted research at the University of Southern California, the University of Virginia, the University of Notre Dame, the Institut National Polytechnique de Grenoble, the Universite de Poitiers, the Friedrich-Alexander-Universitat Erlangen-Nurnberg, the Technische Universitat Munchen, and the Technische Universitat Berlin. He has lectured extensively here and overseas. He is currently the Inez Caudill Eminent Professor of Mechanical Engineering at Virginia Commonwealth University, Richmond, VA 23284; gadelhak@vcu.edu. He was named the Fourteenth ASME Freeman Scholar in 1998. In 1999 he was awarded the Alexander von Humboldt Prize and in 2002 was named ASME Distinguished Lecturer and inducted into the Johns Hopkins University Society of Scholars.

The virtual vehicle

Concerning the topic “Motor Process Simulation in Realtime — Basics and Application Possibilities”, a dissertation was worked out at the Technische Universitat Berlin, which received the “Hermann Appel Preis 2008” in the area powertrain development. This paper reports about the continuation of the scientific work in the current activities of modelling and simulation at IAV GmbH: Straight forward high-fidelity system simulation delivers solutions from module concept evaluation up to real-time application for controls testing ahead of the experiment on the engine dyno or vehicle.