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Emulsion splitting by applying CO2 and pressure
No full textThis investigation is focused on analysing pressurized CO2 injection as a technique for breaking oil-in-water emulsions and proposing an efficient substitute for conventional methods. The destabilisation mechanisms, flotation rate acceleration, and segregation of phases in the system undergo considerable improvement through CO2 microbubbles formation. The ability to effectively separate and isolate aqueous and oil phases is important for treating industrial wastewater, hence optimizing waste reduction and
resource recovery.
The laboratory studies explore various operational parameters, such as CO₂ consumption efficiency, pressure variations, and residence time, in order to optimize splitting in various emulsion mixtures. The studies proved to effectively provide up to 95% total organic carbon (TOC) reduction, particularly achieved in combination with prolonged flotation and settling. Significantly, treatment by CO2-induced separations proved to have most efficiency in synthetic Sodium Lauryl Sulphate (SDS)-based emulsions and in industrial scenarios such as in cooling lubricants. In addition, prolonging flotation time to an overnight timeframe significantly increased TOC reduction in the case of the SDS emulsion.
The presented results offer a new look over the experimental development of separation technologies, demonstrating the effective splitting of emulsions by injecting CO2 without additional pressure input and thus its feasibility in an industrial setting. In addition to providing a chemical-free separation alternative, this method offers the advantage of reduced energy input and the potential for CO2 recapture and reuse as well as oil recovery
Artichoke (Cynara scolymus L.) and climate change: Assessing the potential in German agriculture with insights from Italian practices
No full textArtichoke (Cynara cardunculus var. scolymus) is a crop loved in the Mediterranean, particularly in Italy, where it has a long tradition holding both cultural and economic value. It has many different uses, from fresh consumption to medicinal use and potential in the energy and cheese-making industry. In northern European countries, such as Germany, artichoke cultivation has not been largely present up until now, mostly due to climate limitations, like very cold winters. However, climate change may offer new opportunities for its introduction. This study wants to assess the viability and potential of artichoke cultivation in Germany under current and future climate conditions, with the support of climate reports and literature sources. Past German trials, together with insights from the Italian artichoke cultivation, are integrated into the analysis to offer a better understanding of potential practices and implications for a future cultivation of the crop in Germany. The study concludes that winter cultivation is unfeasible without proper winter protection practices or the development of reliable frost-resistant varieties. However, annual cultivation with harvest within the same season represents a promising option in most German states. Locally grown artichokes could translate into economic and environmental advantages by answering the increasing interest in fresh, healthy, and regionally sourced products. It would also presents an opportunity for diversifying agricultural production in response to climate change and shifting market demands while also filling a gap in the artichoke offer on the market
Identifying Policy Opportunities for the Costa Rican Cocoa Market: A Comparative Analysis with the Dominican Republic
No full textCocoa is a crop native to Costa Rica that once thrived as one of the country’s principal exports. Its decline began in the late 1970s following severe disease outbreaks and has been further affected by a lack of sustained institutional support. This thesis presents a comparative analysis of the cocoa sectors in Costa Rica and the Dominican Republic due to the latter’s good positioning in the global cocoa market. It aims to identify policy opportunities that could support the revitalization of Costa Rican cocoa production. Semi-structured interviews were conducted with stakeholders across both countries and thematically analysed according to six key areas: general characteristics, exports and market access, labour conditions, public policy and framework, support framework, and growth potential. Findings suggest that the Dominican Republic’s success is due to continued governmental prioritization and support, alongside the presence of strong producer associations that facilitate access to post-harvest infrastructure, international markets, and organic certification. In contrast, Costa Rica’s sector remains fragmented, with limited coordination, restricted market access, and minimal governmental support. Nonetheless, recent increases in global cocoa prices and renewed institutional interest have created favourable conditions for reactivating and strengthening the sector. This study highlights the need for strengthened producer organization and culturally grounded support for Indigenous cocoa producers. The broader aim of the study is to enable producers to improve their quality of life through increased profitability
Characterization and Optimization of Process Parameters for Polycaprolactone-based Medical Scaffolds for a Magnetic Planar Drive-based 3D Printer
No full textThis thesis investigates the optimization of process parameters for a Magnetic Planar Drive (MPD)-based 3D printer to fabricate Polycaprolactone (PCL) scaffolds for medical applications. The study aims to identify an optimal set of parameters that ensures high-dimensional accuracy while maintaining structural integrity.
A systematic experimental methodology was adopted, beginning with a full-factorial design to establish baseline parameters for printing temperature (170°C), printing speed (15 mm/s), and nozzle diameter (0.4 mm). A Box-Behnken Design (BBD) was employed to optimize critical parameters, specifically layer height, raster width, and mover levitation height. Analysis of Variance (ANOVA) identified layer height as the most dominant factor influencing dimensional accuracy (p < 0.0001), while raster width and mover levitation had lesser effects.
The experimental validation of the optimization results revealed discrepancies between the numerically and empirically optimized parameter sets. Although the numerically optimized settings had a theoretically superior accuracy of 98.29%, their practical implementation led to structural failures, specifically the collapse of scaffold bridges. In contrast, the empirically optimized set (layer height: 0.2 mm, raster width: 0.45 mm, mover levitation height: 2.25 mm) consistently achieved a mean dimensional accuracy of 97.14% while maintaining stable printability.
The findings demonstrate the potential of MPD-based 3D printing for fabricating medical scaffolds and establishing a validated parameter set
Application of the Ant Colony Algorithm for solving routing optimization problem in logistics
No full textIn logistics there are different options of how the Traveling Salesman Problem can be solved. For that purpose, the Ant Colony Optimization (ACO) may be used. In the thesis, the method is implemented in order to solve the routing optimization problem. In that case, the mathematical application is observed and analyzed. ACO parameters that affecting the working principles were researched in the thesis with the corresponding graphical representation. Based on the theoretical logic the Java language program is written for the purpose of realizing the ACO algorithm. In order to grade the effectiveness of the obtained results the additional model the Greedy method was applied. The developed program tool demonstrates the practical applications and a solution of the routing problem based on the real data in Wesel region. The thesis is focused on the route length optimization and cost reduction in terms of ACO implementation
Buck Converter Control using Gaussian Process Regression
No full textIn this bachelor thesis, I investigate the feasibility of Gaussian Process Regression (GPR) (Williams and Rasmussen 2006) in the control of a buck converter (R. W. Erickson and aksimovic 2020). I develop a prototype digital controller for a buck converter, which uses a trained GPR model to predict the PWM duty cycle required to obtain a desired output voltage. I use an Analog Discovery 2 (AD2) (Digilent Inc. n.d.) as an interface between the GPR controller and the buck converter hardware by providing real-time voltage measurements to the controller and generating the PWM signal. I compare the performance of the GPR controller with the TPS629210DRLR Integrated Circuit (IC) (Texas Instruments 2022), which uses an analog control method and serves as the reference performance standard. I compare the performance of the GPR controller and the IC based on their ability to maintain a target voltage during a load change involving an RC load. The results are evaluated based on the voltage regulation accuracy and load voltage settling time. The results show that both controllers are able to set the load voltage within 1% of the target value. However, the GPR controller has a settling time around 3 times longer than the analog controller. The longer settling time is due to latencies from communication with the AD2 and the time required for duty cycle computation. Despite this, the settling time difference is short enough to consider the digital GPR controller competitive to the reference analog control method, especially since the current prototype is not optimized to reduce these latencies. The findings of this thesis highlight both the potential and limitations of the digital control of a buck converter
Luminescence and Raman spectroscopic data of bacteria with and without exposure to water-soluble polymers (WSPs)
No full textData from luminescence measurements of bacteria exposed to water-soluble polymers (WSPs), as well as Raman spectra of bacteria with and without contact to the WSPs.
Polyacrylamide (PAM) – tested in different molecular weights (e.g., 40,000 g/mol, 150,000 g/mol, 15,000,000 g/mol).
Polyethylene glycol (PEG) – investigated at molecular weights such as 8,000 g/mol, 20,000 g/mol, and 35,000 g/mol.
Polyvinyl alcohol (PVOH) – studied at molecular weights like 16,000 g/mol, 47,000 g/mol, and 61,000 g/mol.
Polyvinylpyrrolidone (PVP) – analyzed in molecular weights such as 24,000 g/mol, 40,000 g/mol, and 360,000 g/mol.
The used bacteria was Aliivibrio fischeri
16/2025 Zugangsprüfungsordnung für Bildungsausländerinnen und -ausländer für den Studiengang International Business and Management an der Hochschule Rhein-Waal vom 04.08.2025
No full textApplication of Carbon Fiber and Advanced Composites in Restorative Dentistry: A Study in Material Efficiency, Manufacturing viability, Market Potential and Innovation.
No full textThis work presents a multidisciplinary evaluation of Carbon Fibre Reinforced Polyether Ether Ketone (CF-PEEK) as a core material for hybrid dental crowns, combined with lithium disilicate (E-max) veneers.
The objective was to assess the mechanical, manufacturing, and economic feasibility of introducing CF-PEEK into restorative dentistry through an engineering-driven approach.
A systematic literature review compared the elastic modulus, flexural strength, and density of CF-PEEK with conventional materials such as zirconia and porcelain-fused-to-metal.
Results show that CF-PEEK exhibits a modulus close to natural dentin and lower density, offering improved biomechanical compatibility and reduced stress transmission.
Additive manufacturing (3D printing) was identified as the most flexible and sustainable production method, minimising material waste and enabling customised crown fabrication.
The study concludes that the CF-PEEK + E-max hybrid crown is mechanically viable and aligns with sustainability goals, though improvements in bonding, colour masking, and clinical validation remain necessary.
This approach demonstrates how industrial engineering tools including TRIZ, QFD, and KANO can effectively guide innovation in dental materials and workflows
Digitizing the Bait Lamina Method: Facilitating Autonomous Learning and Data Processing in Ecological Research
No full textIn recent years, digital tools in soil science have evolved to modernize and streamline traditional approaches by fostering greater learning engagement and enhancing accessibility. The primary goal of this research is to create an application that intends to facilitate autonomous learning while streamlining data processing, visualization, and reporting for the Bait Lamina Method (BLM). Advanced technologies such as React.js, Tailwind CSS, Vite.js, and several Node.js modules were used to implement essential functionalities. Moreover, to ensure smooth and scalable app delivery, Docker was employed. Furthermore, thorough usability testing was carried out with students from both the school and university to create a sturdy app that satisfies the needs and standards of users. This research utilized a mixed-methods approach to evaluate the app's overall usability, emphasizing efficiency, learnability, dependability, and overall satisfaction. Quantitative analysis included phi coefficient correlation, chi-square testing, and multiple ordinary least squares (OLS) regression to measure overall usability and user satisfaction. Meanwhile, qualitative approaches such as theme and sentiment analysis were used to get insight into user experiences, preferences, difficulties, and ideas for improvement. The study demonstrated that understanding the method is a key driver influencing student satisfaction. Therefore, the Bait Lamina App (BLA) immensely facilitated autonomous learning while speeding up data processing, visualization, and administration for the BLM. However, a few small faults and student comments were integrated into the BLA, which improved its use and satisfaction