University Of Siegen Research Articles

Tuning Oxygen Evolving Catalytic Activity of a Precious Metal-Free Nickel Boride by a Cost-Effective Method

The production of hydrogen (H2) by electrochemical water splitting [Green Hydrogen (Green H2)], if driven by green electricity, has attracted considerable interest as an alternative sustainable energy carrier, e.g., in fuel cells for electricity or power and heat generation [1]. However, the lack of satisfactory and cheap electrocatalysts (ECs) to drive the vital electrochemical reactions of hydrogen evolution (HER) and oxygen evolution (OER) in water splitting is the biggest challenge for this technology.Currently, the most advanced electrocatalysts for the two half-reactions of water electrolysis (HER and OER) are noble metal-based materials [2]. Despite the excellent catalytic properties of these noble metal catalysts, their high cost, and scarcity make their commercial use both uneconomical and impractical in low temperature water electrolysis (LT-WE) systems at industrial scale for green H2 as a clean energy alternative to cheaper fossil fuels[3]. In addition to addressing this issue by the development of precious-material-based with a low-loading of precious metal elements, the development of desirable and high-efficiency electrocatalysts (ECs) based on earth-abundant metal elements materials is paramount. However, their catalytic activity is often limited by poor electron transfer, low conductivity, low stability, and small surface area of these materials. Thus, it is crucial to develop earth-abundant metal elements-based materials that are more cost-effective to reduce the high cost of active catalysts for water electrolysis. Although several low-cost materials have already been designed, the potential required for the practical application of water splitting is still very high compared to the theoretical potential (1.23 V), which means that much energy is consumed, which theoretically could be reduced. Due to their remarkable advanced charge transfer and durability for water oxidation in alkaline media, electrocatalysts derived from metal borides-based materials have received a lot of attention as new high-performance catalysts for water oxidation.[4] These properties stem from the multi-dimensional covalent bonding of the metalloid with the surrounding metal atoms.We present here an approach to tune the OER of transition metal borides (TMBs) using the cost-effective and less energy-consuming method that is nevertheless a highly efficient material for OER (Fig. 1). We have developed a low-cost, rational and easily scalable method to enhance the catalytic activity of nickel boride (Ni–B), which requires an annealing process to optimize the catalytic activity. However, this method may have limited applicability on a large scale as it requires a highly inert environment and high-temperature treatment of Ni–B catalysts. We also elucidate a structure-activity relationship using scale-bridging techniques such as TEM and electrochemical characterization. The developed based on non-noble electrocatalysts are prepared by a simple method of chemical reduction of transition metal elements with boron in aqueous solution. The production is a one-step process and the material does not require any further treatment, yet this material shows comparable activity to the state of the art (precious metal-based materials) for OER in alkaline solution at a selected current density. This improved catalytic performance is further corroborated by the microstructural investigations in the TEM. The nanoparticles obtained have an improved porous structure compared to Ni–B and thus provide more available sites for the surface reactions and hence for the catalytic performance of the material. Furthermore, it is shown that activation enables the morphological and structural changes, while some transition metal elements act as sacrificial elements to provide more accessible and stable sites for oxygen-forming centers. This paves the way for a better understanding of metal boride-derived electrocatalysts for water oxidation, a crucial chemical reaction in water electrolysis and other electrochemical energy technologies. Acknowledgements: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 945422. We acknowledge the use of the DFG-funded Micro-and Nanoanalytics Facility (MNaF) at the University of Siegen (INST 221/131-1).

4D-STEM and Eels Analysis of Complex C-Based Sensor Architectures

Transforming high-carbon precursors into open-porous carbon foams and coatings via thermal processes is gaining attention as a sustainable method for various applications, including catalysis, energy utilization, and sensing [1]. In this research, we adopt a one-step laser patterning approach to selectively pyrolyze doctor-bladed ink coatings on flexible PET substrates, thereby producing highly porous, intricately designed CO2 sensor structures with a thickness of about 50 µm. Our ink formulation includes glucose as a pore-forming agent and adenine as a nitrogen source to enhance sensing capabilities. Laser processing in an oxygen-rich setting results in flexible, highly porous sensor heterostructures characterized by distinct areas enriched with nitrogen and oxygen functionalities. The laser intensity’s attenuation with depth leads to the development of a distinctly porous graphitic surface layer (serving as the electrical transducer layer) and a denser nitrogen-enriched lower sensor layer, linked by a narrow transitional region [2]. To understand the formation and functionality of these sensors, we conducted an in-depth TEM analysis of cross-sections of the complete device, prepared through ultramicrotomy cross-sectioning. STEM-EELS elemental distribution maps distinctly show the chemical composition differences between the upper and lower layers of the sensor. Principal component analysis was utilized to separate the complex sensor structures into their constituent crystalline and amorphous carbon and nitrogen-containing phases. 4D-STEM analysis exposed the arrangement of the crystalline graphitic phase and the orientation of graphite basal planes adjacent to the pores of the open-porous sensor. Analyzing these structural parameters is essential for understanding the electrical performance of the sensor, as depicted in Figure 1 [3]. Figure 1: A (top)) SEM micrograph of sensor embedded in epoxy, (bottom) depth-dependent thermal laser intensity attenuation; B (left)) HA ADF-STEM micrograph showing different sensor layers, (middle) STEM-EELS nitrogen distribution map, (right) PCA bond analysis, C) HRTEM images of sensor from transducer (top) and sensor (bottom) layers with SAED image of respective ROIs (inset); D) 4D-STEM analysis depicting misalignment angle between graphitic carbon basal plane normal relative to the pore surface normalReferences[1] M. Hepp, et al. npj Flexible Electronics 6, 1-9 (2022)[2] H. Wang, et al. Advanced Functional Materials 32, 2207406 (2022)[3] C. Ophus, et al. Microscopy and Microanalysis 28, 390-403 (2022) Acknowledgements: We acknowledge use of the DFG-funded Micro-and Nanoanalytics Facility (MNaF) at the University of Siegen (INST 221/131-1). Figure 1

Cross-Sectional Preparation of Complex Energy Devices and Their Characterization By Advanced Microscopic Methods

Energy devices such as batteries, fuel cells, and solar cells are composed of multiple functional components with varying material properties. Achieving a fundamental understanding of structure-property relationships and systematically enhancing performance, while also investigating device degradation and failure mechanisms, requires high-quality cross-sections of entire devices or substantial regions. Given that many devices contain different classes of materials, including liquid and/or air-sensitive components, working under cryogenic or inert conditions is necessary to maintain their original state. To facilitate cross-sectional characterization of these devices from the macroscopic down to the atomic level, we use a range of preparation tools. A self-designed cryo-cutter allows us to efficiently produce cross-sections of entire devices, such as pouch cells, in a single step, enabling optical microscopy (OM) observation at the centimeter scale while preserving their pristine state. For finer scales, cryo-ultramicrotomy and focused ion beam (FIB) techniques are regularly employed. These methods can prepare high-quality thin samples under 50 nm for investigations using OM, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) at atomic resolution. In this presentation, we demonstrate the scale-bridging capabilities of these preparation techniques applied to various devices and their components in conjunction with advanced electron microscopic and spectroscopic methods. Examples include devices such as batteries (Fig. 1) and complex proton exchange membrane (PEM) fuel cells, as well as battery components (Fig. 2). The techniques used are ideal for assessing the integrity of entire devices and the interfaces of individual layers and components, including their morphology, contact, composition, and chemical bonding states. Acknowledgement: Part of this work was performed at the Micro-and Nanoanalytics Facility (MNaF) of the University of Siegen. Figure 1

Guest Editor’s Introduction for Special Dossier on Uncertain Mobilities

Uncertain Mobilities as a special dossier for Migration and Diversity journal originates from the workshop with the same name I organized at the Department of Sociology, University of Siegen in October 2022. The second day of the workshop witnessed participation from early career scholars, including doctoral and postdoctoral researchers, who presented their ongoing research outcomes based on fieldwork conducted across the continents. The day-long discussion paved the way for several subsequent discussions that some of us also pushed further in individual academic publications. As a group of scholars invested in uncertainties and risks in migration research we observed growing interest among academic peers to engage further in this discourse. This special issue is a long-drawn outcome of this collective interest, which authors presenting at the workshop and outside have contributed.

Logic Matters – Gender and Diversity, Too

Abstract This interview features Andrea Reichenberger. Currently she holds a substitute professorship for history of technology at TUM Technical University of Munich. She is junior research group leader at the Department of Mathematics, University of Siegen, Germany, and leads the research project “Rethinking the History of Mathematics and Physics: Women in Focus.” Reichenberger has held several postdoctoral positions, e.g., at the Center for the History of Women Philosophers and Scientists (HWPS) at Paderborn University (Germany) and in the DFG research project “Thought Experiment, Metaphor, Model” at the Institute for Philosophy I at the Ruhr University Bochum. Between 2019 and 2021, she was a fellow at the University of Paderborn and principal investigator of the research project “Foundational research in mathematical logic – relativity – quantum physics. Case studies on the integration of women philosophers.” Reichenberger has written a book on Émilie du Châtelet (Springer, 2016) and has published many articles in journals, collected editions, and encyclopedias.

Hard Wired VIII: Methodical Approaches to Music and Dance: Exploring the Field of Heavy Metal and Its Genre Boundaries, hosted by Florian Heesch, Daniel Suer and Franziska Kaufmann, University of Siegen, Siegen, 8–9 September 20221

The report provides an account of the motivation for hosting a conference on dance in metal before briefly summarizing contributions along the lines of genre-related and methodological questions. It further highlights a dance workshop as part of the conference and reflects on its benefits for the conference format as an academic event that focuses on talks as the primary mode of communicating and negotiating knowledge.

International Polymer Characterization Conference (POLY‐CHAR [Halle|Siegen] 2022)

The International Polymer Characterization Conference POLY-CHAR [Halle│Siegen] 2022 took place as a live digital event from 22nd to 25th May 2022. Organized jointly by the Fraunhofer IMWS in Halle, Germany, and the Institute of Physical Chemistry I of the University of Siegen, Germany, the IUPAC (International Union of Pure and Applied Chemistry)-endorsed conference brought together more than 100 participants from five continents, who shared their research findings ranging from theoretical to experimental and fundamental to applied aspects of polymers. As a a nonprofit, non-governmental organization POLY-CHAR is devoted to creating a friendly interdisciplinary environment to share information, organize student exchange and cooperation, to hold international meetings and to provide a platform for scientist from all over the word. The annual POLY-CHAR conferences are not limited to mere “POLYmer CHARacterization”. Instead, POLY-CHAR offers an open platform for sharing ideas, presenting results, meeting old and making new friends in the scientific community. Topics cover a wide area in synthesis, characterization, modification and application of polymeric materials and composites, probably best summarized under the terms “Advanced Materials' and ‘Functional Materials”. The live digital format chosen for POLY-CHAR [Halle│Siegen] 2022 enabled unrestricted worldwide participation in times of global uncertainty regarding travel restrictions due to the COVID-19 pandemic. On the first day of the conference the POLY-CHAR Short Course was held. The topics of the lectures presented on the subsequent days by 5 plenary speakers, 24 invited speakers, 66 oral speakers, 9 poster presenters from 28 countries included (i) polymer synthesis, (ii) polymer characterization, (iii) polymer physics, theory and simulations, (iv) circular economy of polymers and sustainable applications, (v) polymers for biomedical applications, biopolymers, biomedical materials and biotechnology, (vi) biopolymers in nutrition and health, (vii) elastomers, amorphous materials, nanomaterials and smart materials, (viii) mechanics of polymers, and (ix) adhesives, coatings, and advanced hybrid materials. In addition to several POLY-CHAR and IUPAC prizes for outstanding oral presentations and posters of young scientists, the following prestigious prizes were awarded to well renowned scientists to honor their academic achievements: The Richard Robert Ernst Award went to Prof. Dr. Jianyong Jin (The University of Auckland, New Zealand), the Jean-Marie Lehn Award went to Prof. Dr. Zheng Li (Peking University, China) and the Pierre-Gilles de Gennes Award was awarded to José Luis Gómez Ribelles (Universitat Polìtècnica de València, Spain). This conference volume represents a focused selection of contributions from different areas of polymer and materials science. The next conference in the series, POLY-CHAR [Auckland] 2023, will be held in presence in Auckland, New Zealand, from January 22nd to 26th, 2023. This meeting will be co-hosted by Prof. Jianyong Jin and Prof. Duncan McGillvray. Sven Henning, Fraunhofer IMWS, Germany Ralf Lach, Institut für Polymerwerkstoffe e.V. (IPW), Germany Holger Schönherr, University of Siegen, Germany

The first International Conference on Mechanical System Dynamics grandly convened in Nanjing, China

The first International Conference on Mechanical System Dynamics grandly convened in Nanjing, China

‘Feminism and Metal’, Hosted by Rosemary Lucy Hill and Florian Heesch, online, 15 June 20211

The workshop ‘Feminism and Metal’, 15 June 2021, took place online and was hosted by Rosemary Lucy Hill (University of Huddersfield) and Florian Heesch (University of Siegen). The workshop consisted of seven presentations of research projects in different stages as well as a panel with the Chaos Rising collective, thereby extending beyond academic boundaries. The workshop report provides an insight into the projects presented and the subsequent discussions, and draws out central topics of the workshop.

Facilitating relaxation and stress reduction in healthy participants through a virtual reality intervention: study protocol for a non-inferiority randomized controlled trial

BackgroundRepeated or chronic stress is considered a major source of disease, in terms of both somatic and mental illnesses. The prevention of stress-related disease by interventions for relaxation has thus increased societal relevance. In this randomized controlled non-inferiority trial, we will compare a newly developed virtual reality (VR) environment for relaxation to an active control group applying a freely chosen relaxation method. To test if our VR environment supports relaxation in a situation of acute stress, a standardized stress induction protocol will precede the relaxation phase.MethodsOne hundred healthy participants will be recruited from the University of Siegen and randomly assigned to the VR or the active control group that will be free to choose their own relaxation strategy. The multi-sensory VR includes visual, acoustic, and haptic features to induce a strong feeling of presence. The laboratory testing will comprise a baseline measurement, a stress induction, a relaxation intervention, and a recovery measurement. The primary outcomes are self-reported stress and relaxation measured with a visual analog scale (VAS) at pre- and post-baseline, at the start, middle, and end of the stress induction, at pre- and post-relaxation, at pre- and post-recovery, and in the evening of testing. Secondary outcomes are the physiological parameters, namely heart rate and heart rate variability, tonic skin conductance level as well as the number of non-specific skin conductance responses, systolic and diastolic blood pressure and respiratory rate recorded during the four experimental phases as well as state mood, and state rumination assessed at four time points (pre- and post-stress, post-relaxation, and in the evening of testing). Finally, post-event processing will be assessed after relaxation and in the evening of testing. Repeated measures ANOVAs will be performed to test for statistical effects of group, time, and group × time interaction.DiscussionThe newly developed, multi-sensory VR offers an intervention for relaxation without prior training. Its immersive character might increase efficacy compared to other relaxation methods, especially in situations of acute stress. Future directions could be the development of a mobile version of the VR to enhance accessibility for users. To achieve a transfer of training effects to real life, VR components should successively be eliminated until relaxation is practiced without guidance by the VR.Trial registrationISRCTN Registry ISRCTN11162338. Retrospectively registered on January 22, 2021

Pre-service Teachers’ Reflections on Attitudes Towards Teaching and Learning Mathematics with Online Platforms at School: A Case Study in the Context of a University Online Training

Online learning platforms take over a new role in education, especially in times of the Covid-19 pandemic. This paper will discuss pre-service teachers’ reflections on attitudes towards online learning platforms and the respective changes due to an online training of using this digital tool in mathematics classes. The special training took place in a bachelor seminar with fourteen participants on the use of digital media in mathematics education at the University of Siegen. Based on the ‘Tripartite Model of Attitude Structure’ which defines the psychological concept of attitude, data material about the pre-service teachers’ attitudes is gathered by pre- and post-reflection-questionnaires. A qualitative content analysis led to the formation of a system of six main categories and approximately 51 descriptors for pre-service teachers’ attitudes towards online learning platforms and especially their changes due to the online training of using these platforms. The descriptors can be a basis for further research studies on this topic.

SPI 2022 Held in Siegen, Germany

The Workshop on Signal and Power Integrity (SPI) was held from May 22–25, 2022 in Siegen, Germany. Organized by General Co-Chairs Elmar Griese and Thomas Kühler from the Institute of Theoretical Electrical Engineering & Photonics (University of Siegen), the Workshop was attended by 68 participants.

The Praxeological Research Programme of Socio-Informatics - the Siegen School

This paper introduces the praxeologically grounded research programme on socio-informatics developed at the University of Siegen and the International Institute for Socio-Informatics in Germany. We outline our methodological framework of grounded design, guiding and binding together a variety of different engagements in practice which we call design case studies (DCS). While grounded design is applied to a broad variety of different areas, in this paper we deal specifically with our engagements in support of communities and political activists. To exemplify our approach, we present one DCS: It focuses on the participatory development of a computer club in the High Atlas as a facilitation infrastructure to support public community participation in the process of modernization and social transformation in the Maghreb. Insights into the project context, the objectives and methodology and the depiction of some of its first findings lays the ground for the discussion of socio-informatics research principles.

Non‐destructive damage detection on welded threaded bolts based on electromechanical impedance spectra

AbstractWithin a research project carried out at the Department of Civil Engineering and the Department of Mechanical Engineering of the University of Siegen, a new monitoring method for non‐destructive damage detection on bolts was developed and tested according to its applicability on real life structures. The so‐called EMI‐method is based on the measurement of electromechanical impedance spectra, which change with varying structural states and thus allow for a condition assessment.Structures vibrate in a combination of their natural modes, which can provide information about their structural condition. Their modal characteristics are system‐inherent quantities and are governed by geometry, system stiffnesses and mass allocation. If a system parameter changes, e.g. the bending stiffness of a bridge, this is reflected in the vibration analysis and the modal characteristics. To identify the modal characteristics of civil engineering structures, these are excited and the system response is measured. This principle is also used for damage detection by means of electro‐mechanical impedance spectra (EMI). The observed system‐inherent quantity is the frequency‐dependent mechanical impedance Zs(ω) of the structure. The method is based on the idea that the mechanical impedance of a structure or component to be measured changes as a result of damage (or loss of prestress in the case of bolts) and thus these changes can be detected.In the project, investigations were carried out on steel plates with orthogonally welded threaded bolts, which are used, for example, as fasteners for rail supporting points on bridges. Research objectives were on one hand the detection of the prestress stage and on the other hand the detection of fatigue damage in the weld seam. Within the scope of the project, it has been investigated to what extent a change of the prestressing load can be reliably detected by means of the EMI method. Furthermore, the influence of damage to the bolt on the impedance spectra was investigated.

Fostering Spatial Ability Through Computer-Aided Design: a Case Study

Spatial ability is considered a major factor of intelligence and is increasingly important in times of digitization. This article explores the fostering of spatial ability through computer-aided design software. Different notions of spatial ability will be discussed, and, finally, a concept consisting of five aspects will be described. In addition, literature reviews on the connection between the use of computers and the fostering of spatial ability, as well as on the use of 3D printing technology in mathematics education, are given. Building on this, a case study is presented which examines the work of two middle-school students using computer-aided design software within a workshop at the University of Siegen. From the data material, basic possible actions within such software are derived. These are, based on theory, connected with the five aspects of the specific concept of spatial ability used. The results show various perspectives for the fostering of spatial ability with computer-aided design software.

Methods for online measurement and control of section deviations during hot rolling of wire rod and bars

In the joint project PIREF, the metal forming group of the University of Duisburg-Essen has collaborated with the University of Applied Sciences Ruhr-West Mülheim (Ruhr), the University of Siegen, EMG Automation GmbH and SMS group GmbH to develop sensors, for an online measurement of material velocity and cross section as well as control models for the rolling process of wire rod and bars. The University of Duisburg-Essen provided a metal forming process model for the rolling process to assess the influencing parameters on the rolled section precision. A technique was found to segregate height- from width- influencing parameters from a measured cross-sectional area and actual roll gap. With this measuring technology and with help of the process model, rules for control of the rolling process to achieve close tolerances were obtained. The modelling was accompanied by rolling trials on a laboratory rolling mill at the University of Duisburg-Essen, where a typical Round-OvalRound pass sequence was used for validation of the rolling model concerning lateral spread, inlet and outlet velocity as well as rolling force and torque calculation. The present paper shows how the material flow and the distribution of the velocity in the roll gap can be described. In subsequent rolling of bar and rod in a continuous rolling mill the dimensions can be influenced by application of longitudinal stresses and screwdown. The application of stress can be achieved by an inter-stand velocity mismatch. With the developed models the necessary velocity mismatch can be calculated.

Wetting‐Empowered Surface Functions for Engineering Applications

One of the main characteristics of a surface is its ability to be wetted by a liquid. Surfaces can be explicitly designed for full or poor wetting by different liquid types or for the easy sliding or sticking of droplets. The design of functional surfaces crosses multiple length-scales and includes surface chemical functionalization, micro/nano-engineered surface structures, chemical/physical gradients, elasticity, etc. These design features form the basis for even more complex functionalities. Recent approaches have involved increasingly complex surface architectures and techniques such as controlling droplet shape/motion on slippery liquid-infused porous surfaces (SLIPS), and reducing lateral adhesion by employing the Leidenfrost phenomenon (article number 202001249). The importance of this research is underpinned by its role in resolving global challenges, such as environmental crises, sustainable energy, food and water production and consumption. Established in 2013, the Smart Materials and Surfaces Laboratory (SMSL) in Northumbria University has achieved considerable progresses in the areas of bio-inspired surface/interface science, smart materials, microdevices and systems, leading to a well-recognized profile in scientific significance and academic impact worldwide. The origin of this special issue is based on discussions among Prof. Butt, Prof. Xu, Dr. Li, and Dr. Smith, starting at the Droplets 2019 conference, which was co-organised by the SMSL. At last, we hope this collection of papers provides an interesting benchmark for wetting-empowered technological developments toward the discovery of frontier engineering applications. We appreciate the support from the whole editorial team of Advanced Materials Interfaces and the reviewers. We would like to gratefully acknowledge the contributions from all authors and their co-authors to this special issue, at this unprecedent time. Ben B. Xu is a Professor of Materials and Mechanics and Director of Research and Knowledge Exchange in the Department of Mechanical and Construction Engineering at Northumbria University, UK. Ben obtained his Ph.D. in Mechanical Engineering (2011) at Heriot-Watt University in Edinburgh, then moved to the University of Massachusetts, Amherst (US), to work (2011–2013) with Prof. Ryan C. Hayward as a postdoc. Since joining Northumbria in 2013, Ben has established a multidisciplinary research profile with diverse interests in responsive materials/surface, soft matter, materials chemistry, mechanics, energy materials and technology, and micro-engineering. Yifan Li was appointed as a Senior Lecturer in the Department of Mechanical and Construction Engineering at Northumbria University (UK) in 2014, having been a Research Fellow at the School of Engineering, University of Edinburgh (UK) where he also gained Ph.D. degree in 2008. He studied Engineering with a B.Eng. degree obtained from the School of Electronics and Electrical Engineering at Shanghai Jiao Tong University, Shanghai, China in 2003. Yifan's research interests are droplet microfluidics, microsystems, flexible electronics and transducers. Hans-Jürgen Butt is a director at the Max Planck Institute for Polymer Research (MPIP), Mainz, Germany. He studied physics in Hamburg and Göttingen. He defended his Ph.D. thesis in 1989 at the Max Planck Institute for Biophysics (MPIBP). After one-year postdoc experience at the University of California, he moved back to MPIBP and habilitated in 1995. In 1996, he became an associate professor at the Johannes Gutenberg-University in Mainz. In 2000, he became a full professor at the University of Siegen for Physical Chemistry. In 2002, he joined MPIP as a director working on soft matter interfaces.

Relevant Content for a Scientific Collaboration in Mathematics and Physics Education Research - A Comparative Content Analysis of Handbooks and Conference Proceedings in Germany and Vietnam

This article presents a possible framework for the cooperation of mathematics and physics education research domains. Moreover, the potential topics for such a scientific collaboration are explained by means of a structuring qualitative content analysis of current handbooks and conference proceedings in Germany and Vietnam. These topics can form a basis for further projects on the connection of subject-related didactics. One of these projects is an interdisciplinary course in teacher training at the Hanoi National University of Education (HNUE) as part of the Inter TeTra project between the HNUE and the University of Siegen.

Semantik und Ethik des Wortfeldes “Ergon” im Johannesevangelium

Semantik und Ethik des Wortfeldes “Ergon” im Johannesevangelium

Wind Data Analysis, Annual Resource Estimation And Comparison With Measured Annual Energy Yield at the University Wind Turbine

Evaluation of the power potential of a particular type of wind turbine at a specific site is necessary for economic decisions. Therefore, the information of a wind turbine and that of a site have to be measured or predicted and then combined with the power curve of a wind turbine. The main objective of this research was to predict the power potential of the existing small wind turbine with a diameter of 3m and the wind turbine site at the University of Siegen and compare with the annual energy calculated from the measured one year of wind and turbine data. Techniques for prediction of the wind speed distribution of a site were determined and modeled. The power curve of the wind turbine was modeled from data recorded by applying a technique from the novel methods for modelling the power curve. In this research, artificial neural network, Weibull and Rayleigh are the techniques modeled to predict wind speed distribution at the wind turbine site. Rayleigh and Weibull were chosen since the two models depict a better wind speed distribution and require the mean and the standard deviation of the wind speed at the wind turbine site. A neural network trained with the backward propagation levernberg-Marquardt algorithm was applied to predict the wind speed and power potential of the wind turbine site. A comparison between Weibull, Rayleigh and the Levernberg-Marquardt trained neural network wind speed was made. The power curve of the wind turbine was successfully evaluated from wind data and wind turbine data recorded. The results indicate that the annual mean wind speed of the region is 2.54 (m/s) and about 20% of the wind availability was blowing from the west. The annual energy yield predicted from the trained neural network was 372 (kWh) closer to that determined from measured wind speed 360 (kWh) than that determined from Weibull and Rayleigh 337 and 233 (kWh) respectively. The three prediction models are applicable in any region to predict the annual energy of a particular wind turbine site with minimal data available.