@phdthesis{Ali2025, author = {Ali, Mohammed Liaket}, title = {Detailed numerical modeling of the iron ore direct reduction process}, doi = {10.26127/BTUOpen-6969}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-69695}, school = {BTU Cottbus - Senftenberg}, year = {2025}, abstract = {The iron and steelmaking industry is among the largest contributors to global CO₂, driven by its energy-intensive processes and reliance on carbon-rich fuels. As steel demand rises in an increasingly competitive global market, innovative and sustainable production methods are urgently needed. The Direct Reduction (DR) process using syngas or hydrogen presents a promising approach to reducing CO₂ emissions and energy consumption in steel production. Computational modeling plays a crucial role in accelerating technology development, yet traditional models, such as the shrinking core model, fail to fully capture the complexities of the reduction process. More advanced models are necessary to simulate interactions between iron ore pellets and reducing gases and to scale effectively to industrial applications. To address these challenges, this dissertation introduces an improved porous solid model that overcomes biases in the shrinking core model, accurately representing the reduction of single iron ore pellets in H₂ and CO environments while accounting for carbon deposition and porosity changes. A comprehensive reduction mechanism is developed and validated against extensive experimental data without parameter adjustments, providing a solid foundation for advanced simulations. Besides the stand-alone kinetic model, a Computational Fluid Dynamics (CFD) solver has been developed, bringing the considerations to a spatially resolved environment, including pellet and gas phase regions. Building on the insights gained from single-pellet models, the research advances to the more complex modeling of fixed beds; a crucial step in bridging the gap between detailed small-scale studies and the case of industrial-sized reactors. A comprehensive methodology is developed, incorporating realistic packed-bed structures and high-quality computational meshes, for particle-resolved CFD simulations of the hydrogen-based direct reduction process in a fixed-bed setup. These simulations reveal crucial insights into the reduction process, such as the non-uniform reduction within the bed, the presence of gas pockets, and the impact of temperature variations due to the endothermic nature of hydrogen-based reduction. Finally, the study explores the influence of pellet sizes and shapes in the DR process via different reconstruction techniques, including computed tomography. By examining beds with various particle characteristics and structures, the research highlights the significant impact of these factors on reduction efficiency and overall conversion rates. This comprehensive modeling approach offers critical insights for optimizing the hydrogen-based direct reduction process, paving the way for its application in industrial-scale reactors. By addressing these research questions and providing innovative solutions, this dissertation contributes to the advancement of DR-technology, offering a path toward more sustainable steel production.}, subject = {Kinetics; Kinetik; Stahlherstellung; Direktreduktion; Modellierung; CFD; Steelmaking; Direct Reduction; Modeling; Stahlherstellung; Numerische Str{\"o}mungssimulation; Direkte Eisengewinnung; Modellierung}, language = {en} } @article{AlimovSviridovJenschetal.2023, author = {Alimov, Artem and Sviridov, Alexander and Jensch, Felix and Sydow, Benjamin and H{\"a}rtel, Sebastian}, title = {Additive manufacturing of hot-forming dies using laser powder bed fusion and wire arc direct energy deposition technologies}, volume = {13}, number = {11}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/met13111842}, year = {2023}, abstract = {Additive technologies are now widely used for the production of complex precise parts and have high potential for the production of forming dies. In this work, hot-forming dies optimized for additive manufacturing were developed and produced with wire arc direct energy deposition (WA-DED) and laser powder bed fusion (L-PBF) technologies. The concept of lightweight hot-forming dies with a 2D-lattice structure was developed, which reduced the weight of each die by 56\%, from 14.2 kg to 6.1 kg, in production using L-PBF. Maraging/precipitation-hardened steel 17-4PH was used as an alternative to traditional hot-working steels with slightly lower mechanical properties and a much higher processability in the additive manufacturing process. The workability of the manufactured dies was confirmed by forging tests on an industrial screw press.}, subject = {Additive manufacturing; Hot-forming dies; L-PBF; WA-DED; WAAM; Additive Fertigung; Warmumformwerkzeuge; L-PBF; WA-DED; WAAM; Warmumformen; Rapid Prototyping (Fertigung); Selektives Laserschmelzen}, language = {en} } @phdthesis{Allgoewer2001, author = {Allg{\"o}wer, G{\"u}nther}, title = {Bemessung von Stahlbetondruckgliedern unter zweiachsiger Biegung mit Interaktionsdiagrammen nach Theorie II. Ordnung}, issn = {1436-9532}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000160}, school = {BTU Cottbus - Senftenberg}, year = {2001}, abstract = {Das Ergebnis der vorliegenden Arbeit sind grafische Bemessungshilfen in Form von Interaktionsdiagrammen f{\"u}r Stahlbetondruckglieder mit zweiachsiger Biegung. Bei der Anwendung der Diagramme wird die bisherige Einschr{\"a}nkung auf den ebenen Fall aufgehoben. Es stellt sich somit der ebene Fall lediglich als Sonderfall des r{\"a}umlichen Zustandes dar. Grundlage f{\"u}r das verwendete Rechenverfahren nach Theorie II. Ordnung ist eine von der Ebene auf den Raum erweiterte Modellst{\"u}tze. Diese virtuelle Kragst{\"u}tze mit gleichen oder unterschiedlichen Ersatzl{\"a}ngen in den beiden Achsrichtungen dient als statisches System, an welchem alle Berechnungen durchgef{\"u}hrt werden. Es zeigte sich, dass die Verwendung der Betonarbeitslinie die urspr{\"u}nglich nur f{\"u}r die Querschnittsbemessung vorgesehen ist, auch bei Anwendung in der Traglastberechnung zu einer guten {\"U}bereinstimmung zwischen rechnerischen und experimentellen Ergebnissen f{\"u}hrt. Die Mitwirkung des Betons auf Zug zwischen den Rissen ("Tension-stiffening"-Effekt) sollte beim Tragf{\"a}higkeitsnachweis nicht angesetzt werden, da dadurch die Traglasten teilweise erheblich {\"u}bersch{\"a}tzt werden.}, subject = {Druckglied; Stahlbeton; Tragverhalten; Biegung; Bemessung; Stahlbeton; Druckglied; Bemessung}, language = {de} } @misc{AlpirezBock2015, type = {Master Thesis}, author = {Alpirez Bock, Estuardo}, title = {SCA resistent implementation of the Montgomery kP-algorithm}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-36288}, school = {BTU Cottbus - Senftenberg}, year = {2015}, abstract = {Mathematically, cryptographic approaches are secure. This means that the time an attacker needs for finding the secret by brute forcing these approaches is about the time of the existence of our world. Practically, an algorithm implemented in hardware is a device that generates a lot of additional data during the calculation process. Its power consumption, electromagnetic radiation, etc. can be measured, saved and analysed for key extraction. Such attacks are called side channel analysis attacks and are significant threats when applying cryptographic algorithms. By considering these attacks when implementing a cryptographic algorithm, it is possible to design an implementation that is more resistant against them. The goal of this thesis was to design a methodology to securely implement the Montgomery kP-operation using an IHP implementation as a starting point. In addition, the area and energy consumption of the secure Montgomery kP-multiplier should still be highly efficient. The resistance against power analysis attacks of two different IHP ECC implementations was analysed in this thesis. A horizontal power analysis attack using the difference-of-means test was performed with the goal of finding potential leakage sources exploited in side channel analysis attacks, i.e. finding the reasons of a correct extraction of the cryptographic key. For both analysed ECC designs, four key candidates were extracted with a correctness of 90\% or more. Through analysis of the implemented Montgomery kP-algorithm's functionality and its power consumption, it was established that the algorithm's operation execution flow was the main cause of the implementations' vulnerability. Thus, a design methodology consisting in changing the Montgomery kP-algorithm operation flow was developed. As a result, the re-designed implementations do not deliver any correctly extracted key candidates whenever the difference-of-means test is performed on them. These re-designs implied an increase on the chip area by about 5\% for each implementation. The execution time needed for performing a complete kP-operation was reduced for both designs. Thereby one implementation's execution time was reduced by 12\% in comparison to its original version and even though its power consumption was increased by 9\%, its energy consumption per kP-operation was reduced by 4.5\%.}, subject = {Side channel analysis; Elliptic curve cryptography; Power analysis; Difference-of-means test; Elliptic curve point multiplication; Elliptische Kurve; Kryptologie}, language = {en} } @phdthesis{Alsabbagh2023, author = {Alsabbagh, Wael}, title = {Investigating security issues in programmable logic controllers and related protocols}, doi = {10.26127/BTUOpen-6611}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-66114}, school = {BTU Cottbus - Senftenberg}, year = {2023}, abstract = {Programmable Logic Controllers (PLCs) are pivotal in Critical Infrastructures (CIs) and Industrial Control Systems (ICSs), governing processes in nuclear power plants, petrochemical factories, and water treatment systems. Despite their importance, PLCs are vulnerable to security threats, notably control logic injection attacks, aiming to sabotage physical processes. This thesis delves into PLC security, analyzing vulnerabilities in non-cryptographically and cryptographically protected PLCs, particularly Siemens S7-300 and S7-1500 models. Siemens, an automation market leader, utilizes S7-300 PLCs in millions of applications, reflecting the broader ICS security landscape. The S7-1500 line claims resistance to cyberattacks, including control logic injections. The thesis evaluates authentication in non-cryptographically protected PLCs, introducing a stealthy control logic injection attack scenario using an S7-300 PLC and S7Comm protocol. The second part explores integrity checks in cryptographically protected S7-1500 PLCs. Findings, encompassing disclosed vulnerabilities, lead to a severe control logic injection attack with a malicious interrupt block, conducted in an industrial setting using the S7-1500 and S7CommPlus protocol. The final segment focuses on Profinet protocol security and an injection attack scenario. The study demonstrates adversaries manipulating critical data without prior knowledge, causing harm to physical processes. A real-world attack on a Profinet-based system with two S7-300 PLCs is executed. The thesis concludes by proposing mitigation solutions, enhancing PLC and communication protocol security. This contribution elevates the security posture of millions of operating devices globally, advancing PLC security research.}, subject = {Programmable logic controllers; Control logic injection; Cyberattacks; Cybersecurity; False data injection; Speicherprogrammierbare Steuerungen; Control Logic Injection-Angriffe; Cyberangriffe; Cybersischerheit; False Data Injection-Angriffe; Kritische Infrastruktur; Kontrollsystem; Speicherprogrammierte Steuerung; SIMATIC S7-300; SIMATIC S7-1500; Computersicherheit; Cyberattacke}, language = {en} } @phdthesis{Alzoobi2003, author = {Alzoobi, Abed}, title = {Objektorientierte Modellierung der Kosten in Hochbauprojekten}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-000000460}, school = {BTU Cottbus - Senftenberg}, year = {2003}, abstract = {In dieser Arbeit werden Ans{\"a}tze zur Softwareentwicklung auf Objektorientierter Basis im Bereich der Kosten in Hochbauprojekten beschrieben. Die Konzepte der Objektorientierten Technologie zur Softwareentwicklung werden in dieser Arbeit umfassend eingesetzt. Zur Modellierung des Systems wird die Unified Modeling Language (UML) eingesetzt. Die bedeutenden Gesichtspunkte dieser Modellierung sind die Entwicklung des Objektmodells in der Analysephase und deren Verfeinerung in der Entwurfsphase. Dieses Objektmodell bildet die Basis bei der Softwareentwicklung im bereich der Kosten in Hochbauprojekten. Im Rahmen dieser Modellierung werden auch die Aspekte der Soft- und Hardwareverteilung spezifiziert. Ferner werden Konzepte zur Implementierung der Ergebnisse der Modellierung erl{\"a}utert. Hier wird das Objektmodell des Systems in die Programmiersprache Java {\"u}bersetzt.}, subject = {Hochbau; Bauvorhaben; Baukosten; Softwareentwicklung; Vorgehensmodell; UML; Objektorientierte Modellierung; Kosten; Hochbauprojekt}, language = {de} } @phdthesis{Amanpour2022, author = {Amanpour, Saman}, title = {A cellular approach to optimize the integration of renewable generation into distribution networks}, doi = {10.26127/BTUOpen-5900}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-59009}, school = {BTU Cottbus - Senftenberg}, year = {2022}, abstract = {The steady growth of the renewable-based technologies in the last twenty years has changed the character of the power systems significantly. Until today, there are more than 112 GW installed photovoltaic and wind parks in Germany and around 90\% of the installed renewable generators are integrated into distribution networks. As a result, distribution networks are often facing congestion problems and more investments are needed for the required network development plans. The political decisions in Germany for increasing the share of renewables in electricity consumption up to 65\% until 2030 and the nuclear phase out until 2022 and further shutdowns of the coal power plants raised serious concerns about the reliability of power supply and feasibility of the transition plan. The present dissertation has a look over the recent developments and offers a methodology for reduction of the resulted costs from further integration of renewable generators into the distribution networks. The suggested methodology is based on a cellular approach and helps also to postpone the unnecessary costly network expansions. Furthermore, it helps to integrate the renewable generators in an optimized way which has an added value to move towards the defined sustainability goals. The proposed methodology has two steps. The first step is made up of the cellular approach and grey wolf optimization in MATLAB environment. In this step, the optimal combination of technologies for fulfillment of the defined goals are found out. The second step consists of the quasi dynamic simulations in PowerFactory environment. In this step, the suggested results from MATLAB optimization are investigated in semi-real situations. With the quasidynamic simulations, it is checked whether the results are tolerable from the point of view of network operation and whether it is possible to facilitate the network operation with certain strategies.}, subject = {Cellular approach; Optimization; Renewable energy; Generation; Distribution networks; Zellularer Ansatz; Optimierung; Erneuerbare Energien; Erzeugung; Verteilnetze; Verteilungsnetz; Erneuerbare Energien; Elektrizit{\"a}tserzeugung; {\"U}bertragungsnetz; Netzstabilit{\"a}t (Elektrische Energietechnik)}, language = {en} } @phdthesis{Ampadu2025, author = {Ampadu, Kwame Owusu}, title = {Road traffic gesture autonomous integrity monitoring}, doi = {10.26127/BTUOpen-7222}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-72226}, school = {BTU Cottbus - Senftenberg}, year = {2025}, abstract = {Sensor enabled smart vehicles are predicted to succeed beyond human capabilities, thereby eliminating handling errors intrinsic to human driving. Driverless vehicles must be capable of detecting and responding to exaggerated ad hoc bodily movements that humans use to maintain road traffic safety. These nonverbal communication cues may be used to ease traffic flow, control infotainment systems or restore minimal risk conditions. The integration of sensor fusion techniques and high-quality benchmark datasets coupled to high throughput general purpose graphics processing units is spawning complex heavyweight algorithms useful for traffic scene understanding. These advanced methods are expensive in terms of costs related to hardware, software and energy consumption. Yet, the autonomous vehicle lacks the ability to participate in gestural exchanges. Following extensive evaluations of recent technological advancements in gesture detection and recognition in dynamic traffic environments, a new communication technology has been created for interaction between autonomous and traditional vehicles at unsignalized four-way intersections. This system operates without relying on most conventional navigation sensors and algorithms, allowing autonomous vehicles to communicate with traditional vehicles at intersections through in-vehicle traffic lights that utilize fuzzy logic. The algorithm implemented on low-cost microcontrollers can disperse road traffic and also perform extended blind spot detection. A single sensor is utilized, which remains largely unaffected by adverse weather conditions. The system requires no internet connectivity. It also avoids the need for large scale or long-term data storage, such as the driving cloud platform, ensuring backward compatibility with traditional vehicles. Simulations were conducted based on the order and direction of arrival at three junctions. Results have shown that autonomous vehicles at four-legged intersections, can now communicate with human drivers at a much lower cost achieving precise location classification and lane dispersion in under 30 seconds. This pioneering innovation presents an opportunity to turn every four-way intersection into a signalized junction at zero cost to governments.}, subject = {Advanced Driver Assistance System (ADAS); Autonomous vehicle; Fuzzy logic; Gesture recognition; In-vehicle traffic light; Fahrerassistenzsystem; Autonomes Fahrzeug; Fuzzy-Logik; Gestenerkennung; Fahrzeugintegrierte Ampel; Autonomes Fahrzeug; Fahrerassistenzsystem; Gestenerkennung; Fuzzy-Logik}, language = {en} } @phdthesis{An2015, author = {An, Ni}, title = {Statistical analysis of extreme climate events in Brandenburg}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-36117}, school = {BTU Cottbus - Senftenberg}, year = {2015}, abstract = {The main idea of this paper is to evaluate the performance of the fine resolution CLM model in the state of Brandenburg Germany, create a bias correction method and reanalyze the climate signals of the corrected simulations on projections of the 21st century. The bias correction method is a distribution oriented method and the analysis is mainly focused on the extreme events such as 95 and 5 percentile daily temperatures and 95 percentile daily precipitations in a period of 30 years, but also includes seasonal temperature, daily temperature difference and monthly precipitation to demonstrate the effectiveness of the correction method. The results showed that the correction method was very effective on different variables. After correction, the extreme daily temperature bias was reduced from a cold bias of 1-2K to less than 0.1K. The corrected projection simulations suggested that the extreme temperatures were about to increase both in intensity and in frequency. The extreme precipitation after correction was meant to become more severe and frequent as well.}, subject = {Bias correction; Climate simulation; CLM model evaluation; Climate signal analysis; Bias Korrektur; Klima Simulation; CLM Modell Auswertung; Klima Signal Analyse; Brandenburg; Klima; Modell; Statistische Analyse; Simulation}, language = {en} } @phdthesis{Andolfo2017, author = {Andolfo, Franco}, title = {Energieeffizientes N{\"a}hrstoffsplitting von fl{\"u}ssigen Wirtschaftsd{\"u}ngern mittels Membranfiltration}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-42805}, school = {BTU Cottbus - Senftenberg}, year = {2017}, abstract = {Die definierte Selektivit{\"a}t der Membranfiltration kann dazu genutzt werden, einzelne spezifische G{\"u}lle-Separationsprobleme in {\"u}bergeordneten Aufbereitungsklassen zusammenzufassen. Mit dem Ansatz einer gesteuerten N{\"a}hrstofftrennung bzw. Teilzusammenf{\"u}hrung von modifizierten Str{\"o}men, und der Zuordnung von spezifischen Aufgaben an die Mischprodukte, werden die Nachteile des Ausgangsrohstoffs reduziert und der Wertstoff G{\"u}lle r{\"u}ckstandsfrei nutzbar gemacht. Mit einem Anlagenmodell, bestehend aus einer Hydrotankpresse als Vorfiltration und einer Ultrafiltration als Kernkomponenten, ist es {\"u}ber empirisch ermittelte Betriebsparameter m{\"o}glich, einen energetisch optimierten und kontinuierlichen Produktionsbetrieb durchzuf{\"u}hren. Als Produkte der dezentralen Aufbereitungsanlage werden ein emissionsreduzierender Fl{\"u}ssigd{\"u}nger, eine als Brennstoff und als G{\"a}rsubstrat geeignete Feststoffphase, sowie das Retentat als aktivierendes Material zur Biogasertragssteigerung gewonnen. Das untersuchte Anlagenmodell ist auf den innerbetrieblichen Einsatz in Milchviehhaltungsbetrieben abgestimmt. Mit der Erarbeitung von stabilen und energetisch g{\"u}nstigen Anlagenbetriebspunkten wird das Anlagenverhalten hydraulisch steuerbar. Durch die Zuordnung von Anlagenzust{\"a}nden zu differenziertem Sp{\"u}lverhalten, wird die direkte Einflussnahme der Temperatur auf den Permeat-Flux erkennbar. Der Einsatz eines Tauchk{\"u}hlers, mit voreingestellten Grenztemperaturen, stabilisiert signifikant das Anlagenverhalten im Vergleich zu konventionellen Anlagenkonfigurationen. Die Anwendung einer Hydropresse gestattet h{\"o}here TDS-Belastungen im UF-Kreislauf, bietet aber kein Potenzial zur Steigerung der N{\"a}hrstoffdurchs{\"a}tze. Dies gilt auch f{\"u}r den Einsatz einer 300 kDa-Variante, im Vergleich zur priorisierten 150 kDa-UF-Membran. Mit der Hydropresse kann eine h{\"o}here Feststoffabscheidung wie mit Verstopfungs- bzw. Siebfiltrationen erreicht werden, die TDS-Belastungen sind im Retentat auf 5.000 - 7.000 ppm limitiert, oder m{\"u}ssen durch Verd{\"u}nnung auf diese Werte eingegrenzt werden. Mit der zus{\"a}tzlichen Anwendung einer Gassp{\"u}lung in der Anstr{\"o}mung der UF-Module, k{\"o}nnen TDS-Belastungen {\"u}ber 10.000 ppm erstmals dauerhaft bew{\"a}ltigt werden. {\"U}ber die so erweiterte Verfahrenstechnik sind Standzeiten von mehreren Wochen, ohne betrieblich bedingte Unterbrechungen, m{\"o}glich. Die durch Fluoreszenzmikroskopie nachweisbare Anreicherung von Methanbildnern im Retentat, best{\"a}tigt eine m{\"o}gliche Anwendung des Retentats als Biogassubstraterg{\"a}nzung. Der Biogasertrag wird durch Zusatz von Retentat zu den bisher verf{\"u}gbaren Substraten generell erh{\"o}ht. Eine Mischung aus Retentat und dem Feststoff aus der Hydropresse unterst{\"u}tzen die biochemische Stabilisierung in Fermentern. In Kombination mit Anteilen an Feststoff ist das Permeat bei der Bewertung von pflanzenbaulichen Ertr{\"a}gen, als konkurrenzf{\"a}hig zu Rohg{\"u}lle und Mineralstoffd{\"u}nger einzustufen. Das auf landwirtschaftliche Fl{\"a}chen ausgebrachte Permeat ist geruchslos.}, subject = {N{\"a}hrstoffsplitting; Nutrient splitting; Membranfiltration; Membrane filtration; Wirtschaftsd{\"u}nger; Farm fertilizer; Klimaschutz; Climate protection; Umweltschutz; Environment protection; Membranfilter; Wirtschaftsd{\"u}nger; Technikumsanlage; Klimaschutz}, language = {de} }