@masterthesis{Zhong, type = {Bachelor Thesis}, author = {Zhong, Gantong}, title = {Calibration and Performance Evaluation of Contactless Optical Position Sensors Based on 3D Printed Optical Waveguides}, address = {Regensburg}, doi = {10.35096/othr/pub-8466}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-84668}, school = {Ostbayerische Technische Hochschule Regensburg}, pages = {35}, abstract = {This work presents the design, implementation, and performance evaluation of a positionsensing system based on a 3D printed optical waveguide. Building upon the conceptual foundation of D-shaped polymer optical fiber (POF) sensors [1], this study introduces a novel waveguide structure fabricated via multi-material fused filament fabrication (FFF) 3D printing. The waveguide incorporates a square-core geometry with integrated mechanical brackets and selective black cladding layer to enhance optical confinement and minimize boundary-induced nonlinearity. Three successive design iterations were developed and evaluated, with each version refined based on calibration results and structural observations. The final version demonstrated high fabrication stability and improved optical behavior, enabling consistent calibration across multiple samples. Using a center-corrected linear attenuation model, the position of a side-coupled LED was estimated from dual photodiode signals and compared with true light source position. The measurement results for five independently printed waveguides show mean absolute errors below 0.2 mm and standard deviations as low as 0.268 mm. The sensor response was found to be highly linear over the 5-55 mm sensing range, with worst-case errors bounded within ±1.7 mm. Compared with traditional D-shaped POF sensors, where performance is limited by manual polishing variability and nonuniform attenuation, the 3D-printed approach offers superior linearity, submillimeter accuracy, and batch-to-batch reproducibility. These findings prove the feasibility of 3D-printed optical waveguides in scalable and precise position sensing applications, marking a further step toward the batch fabrication and and potential industrialization of contactless optical position sensors. A conclusion of the research findings and suggestions for future improvements were provided at the end of this thesis, offering insights for the further development in this area.}, language = {en} } @article{HausladenSchelsBuchneretal., author = {Hausladen, Matthias and Schels, Andreas and Buchner, Philipp and Bartl, Mathias and Asgharzade, Ali and Edler, Simon and Wohlfartsst{\"a}tter, Dominik and Bachmann, Michael and Schreiner, Rupert}, title = {Measurement of field emission array current distributions by metal-coated CMOS image sensors}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, publisher = {AIP Publishing}, doi = {10.1116/6.0004074}, abstract = {A CMOS image sensor is utilized to determine the time- and spatially resolved distribution of the total electron emission current of a silicon field emission array. The sensor measures electron emission without the need for phosphorus screens or scintillators as converters. However, in initial experiments, rather low field emission currents of several hundreds of nanoamperes per emitter already damaged the sensor surface, which altered the systems' signal response over the measurement time. In consequence, we coated the CMOS sensor surface with a Cu layer for surface protection. In contrast to the original insulating surface, Cu is an excellent current- and heat-conductor, which avoids lens charging by providing a conductive path for incident electrons and has an improved heat dissipation capability. Measurements using a segmented field emission cathode with four individually addressable tips demonstrate a consistent correlation between the emission current and the sensor signal of the metal-coated image sensor. Furthermore, the characterization of a field emission array showed that single tip emission currents of up to 12 μA per tip are measurable without discernible damage effects of the sensor's surface.}, language = {en} } @article{SchreinerWiedmannCoenningetal., author = {Schreiner, Rupert and Wiedmann, J. and Coenning, W. and Porsche, J. and Gentner, Jean-Louis and Berroth, Manfred and Scholz, Ferdinand and Schweizer, H.}, title = {Fabrication approach for antiphase narrow linewidth complex coupled 1.55 μm DFB lasers}, series = {Electronics Letters}, volume = {35}, journal = {Electronics Letters}, number = {2}, publisher = {The Institution of Engineering and Technology IET}, issn = {0013-5194}, doi = {10.1049/el:19990132}, pages = {146 -- 148}, abstract = {A new method for fabricating narrow linewidth antiphase complex coupled MQW DFB lasers by periodically etching the active layer and quartemary InGaAsP overgrowth is reported. The minimum linewidth for a 375 µm long ridge waveguide laser is only 250 kHz at an optical output power of 4 mW.}, language = {en} } @article{HausladenSchelsAsgharzadeetal., author = {Hausladen, Matthias and Schels, Andreas and Asgharzade, Ali and Buchner, Philipp and Bartl, Mathias and Wohlfartsst{\"a}tter, Dominik and Edler, Simon and Bachmann, Michael and Schreiner, Rupert}, title = {Investigation of Influencing Factors on the Measurement Signal of a CMOS Image Sensor for Measuring Field Emission Currents}, series = {Sensors}, volume = {25}, journal = {Sensors}, number = {5}, publisher = {MDPI}, doi = {10.3390/s25051529}, pages = {17}, language = {en} } @article{SchwarzPastoetterTranetal., author = {Schwarz, Tobias and Past{\"o}tter, Angelina and Tran, T. H. and Schlosser, Marc and Kaulen, Corinna and Lechner, Alfred and Slabon, A. and Kammler, Martin}, title = {Effect of temperature on the growth of Cupric and Cuprous Nanoparticles in a wet chemical synthesis}, series = {Materials Letters}, volume = {381}, journal = {Materials Letters}, publisher = {Springer Nature}, doi = {10.1016/j.matlet.2024.137672}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79279}, abstract = {Cuprous oxide (Cu2O) and cupric oxide (CuO) particles were synthesized using a wet chemical surfactant free method at different synthesis temperatures from 25 °C to 60 °C. Morphology, size, and chemical composition of the prepared Cu2O particles were analyzed by FESEM, PXRD, and UV-vis. We discovered that the chemical composition of the Cu2O particles remained unaffected by the synthesis temperature. However, morphology and size of the particles showed a strong temperature dependency. This could be attributed to the temperature induced formation of CuO species from the copper hydroxide (Cu(OH)2) precursor which also functions as copper precursor for the Cu2O particle growth. The cupric oxide species was determined to be the main cause for the formation of micrometer sized particles, whereas with the Cu(OH)2 precursor species for the Cu2O particles nanocubes with smaller edge lengths as well as octahedrons were obtained.}, language = {en} } @inproceedings{ŁawrowskiLangerSchreineretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Sellmair, Josef}, title = {Nano Emitters on Silicon Pillar Structures generated by a Focused Electron Beam Induced Deposition}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520059}, pages = {1-2}, abstract = {Nano emitters were deposited by focused electron beam induced deposition of Trimethyl-(methylcyclopentadienyl)platinum(IV) on top of silicon pillars. The nano emitters were exactly positioned in the center on the top of up to four pillars of a quadratic arranged array of sixteen pillars with a pitch of 50 μm. Integral field emission measurements were performed in a diode configuration with a 50 μm mica spacer in a vacuum chamber at pressures of about 10 -9 mbar. The Fowler-Nordheim plots show a linear behavior, like expected for an n-type silicon material and a metal needle. The I-V measurement of the most promising sample shows an integral emission current up to 2 μm at a voltage of 600 V (12 MV/m) and an onset voltage for a current of 1 nA of about 300 V.}, language = {en} } @inproceedings{BresinskyBrischar, author = {Bresinsky, Markus and Brischar, Jule}, title = {Between association and dissociation : the legitimacy politics of CIMIC experimentation}, publisher = {CCOE}, doi = {10.35096/othr/pub-8562}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-85627}, pages = {21}, abstract = {NATO's Concept Development and Experimentation (CD\&E) works well for discrete technologies but is ill-suited to civil-military cooperation (CIMIC), where the 'capability' at stake is an interorganisational relationship. Drawing on regime-complex theory and organisational sociology, this paper argues that willingness to engage in joint CIMIC capability development hinges on legitimacy rather than technical utility. A legitimacy-scale metaphor captures the trade-off: functional gains from collaboration load one side; identity risks, such as threats to neutrality, autonomy, or safety, load the other. Three ideal-type cases test the framework. In stabilisation missions, humanitarian neutrality is vital, the scale tips toward identity risk, and co-creation remains siloed. In sudden-onset disasters, shared life-saving objectives reduce identity costs, functional incentives dominate, and integrated trials flourish. Territorial- and collective-defence scenarios occupy the middle ground: acute threat perception opens selective, often low-profile windows for cooperation, yet unresolved legal and reputational questions still temper overt collaboration. The analysis yields five practical lessons. First, legitimacy must be treated as a primary design variable. Second, the optimal depth of cooperation is context specific. Third, legitimacy-sensitive 'safe-to-fail' spaces - wargames, living labs, tabletop exercises - lower entry barriers. Fourth, structured reflection on legitimacy exposes red lines early and refines future joint efforts. Fifth, incremental processes can build trust and gradually relax legitimacy constraints. Recognising legitimacy as both constraint and resource allows practitioners to design CIMIC co-creation - and eventual experimentation - that is technically sound, politically acceptable, and ethically sustainable.}, language = {en} } @masterthesis{Xu, type = {Bachelor Thesis}, author = {Xu, Zhiming}, title = {Electronic circuit design and implementation of a contactless optical position measurement device}, address = {Regensburg}, doi = {10.35096/othr/pub-8520}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-85201}, school = {Ostbayerische Technische Hochschule Regensburg}, pages = {49}, abstract = {This thesis presents the design and implementation of a low-cost, highprecision analog front-end for a non-contact optical displacement measurement system. While the principle of sensing based on D-shaped optical fibers is well-established, its practical replication faces challenges of poor consistency from manual polishing and high material costs. To address these issues, we employ 3D-printed polymer waveguides as the core sensing medium and design a dedicated signal conditioning circuit to accompany it. The core work of this thesis revolves around a dual-channel, two-stage amplifier analog front-end. The circuit converts weak, nanoampere-level (nA) photocurrents from the photodiodes into voltage signals. These signals are stable, linear, and suitable for the microcontroller (MCU) to process. The entire design follows this workflow: starting from theoretical calculations, the circuit's performance in frequency domain, time domain, and noise was verified through LTspice simulation. Subsequently, the design was realized in hardware via PCB implementation, including guard rings. The experimental results show that the performance of the fabricated circuit is consistent with simulation. When integrated with the 3D-printed waveguide, the complete system performed end-to-end calibration and decoding. Over a 50 mm measurement range, the system achieved a maximum absolute error of less than 0.81 mm and a root mean square error below 0.4 mm. This research validates the feasibility of a complete, low-cost, non-contact displacement measurement solution—from the sensing structure to the signal processing—suitable for small-scale use.}, language = {en} } @inproceedings{ShahabUllahShehzadetal., author = {Shahab, Muhammad and Ullah, Abdul Wahab Usman and Shehzad, Muhammad and Shah, Syed Bilal and Joyo, M. Kamran and Khan, Sheroz}, title = {Optimal distributed generation placement in radial distribution system using particle swarm optimization}, series = {2024 IEEE 9th International Conference on Engineering Technologies and Applied Sciences (ICETAS)}, booktitle = {2024 IEEE 9th International Conference on Engineering Technologies and Applied Sciences (ICETAS)}, publisher = {IEEE}, doi = {10.1109/ICETAS62372.2024.11120307}, pages = {7}, abstract = {This paper addresses losses of power in Radial Distribution Systems (RDS), which significantly affect voltage levels and operational costs. The main aim is to optimize the positioning and size of Distributed Generation (DG) units, including Photovoltaic (PV) cells, and Wind Turbines (WT), to analyze the effect of DG placement in reducing the losses in power and enhancing the voltage profiles in radial distribution system (IEEE 33 bus system). This research employs Particle Swarm Optimization (PSO), a robust algorithm well-suited for tackling non-linear optimization issues in order to identify the appropriate placement and size for DG units. A number of scenarios with varying numbers of DG units are simulated, indicating significant reductions in active as well as reactive power losses. Likewise, the consistency and reliability requirements of modern distribution systems are improved as the voltage profile is improved. The key findings demonstrate that optimal DG integration enhances system efficiency, contributes to operational cost savings, and improves grid stability. PSO was chosen for its ability to effectively balance computational effort while achieving high accuracy in minimizing the losses associated with power and enhancing voltage profiles. In contrast to traditional optimization techniques, PSO offers superior accuracy and efficiency in addressing the challenges of non-linear optimization in RDS.}, language = {en} } @article{DiachkovaNikolaevaGuertler, author = {Diachkova, Yana and Nikolaeva, Sofiya and Guertler, Katherine}, title = {Communication in International Humanitarian Relief: Profiling Ukrainian Boundary Spanners}, series = {Journal of Intercultural Communication}, volume = {25}, journal = {Journal of Intercultural Communication}, number = {1}, publisher = {ICR Publications}, issn = {1404-1634}, doi = {10.36923/jicc.v25i1.1019}, pages = {98 -- 106}, abstract = {Boundary spanning—the actions and roles individuals or organizations undertake to bridge differences and facilitate communication, collaboration, and understanding across diverse cultural, organizational, or geographical divisions—is an essential element of international cooperation. Set against the backdrop of the Russia-Ukraine war, The purpose of this study is to explore the type of boundary spanning in this uncertain context, the linguistic characteristics of boundary spanners, the necessary skills and competencies required to navigate the complex socio-political landscape, and the role of boundary spanners in humanitarian assistance. This study employs a qualitative research approach, using semi-structured interviews with informants actively engaged in relief efforts and cross-cultural collaboration. The findings emphasized the significance of English as the primary language of communication, the importance of cultural sensitivity and awareness, and the need for intercultural competence in effective boundary spanning. The study concludes with insights from the ongoing Ukrainian experience of bridging geodemographic boundaries and the role of boundary spanners in this process, highlighting key aspects of boundary spanning. Overall, the study contributes to the theoretical background of boundary spanning and enhances the understanding of how linguistic and cultural boundary spanning can drive positive change and improve outcomes in humanitarian aid. The implications of this study suggest that underscore the critical need for collaboration with experienced boundary spanners in educational settings.}, language = {en} }