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Techno-ökonomische Bewertung eines PEM-Elektrolysesystems zur erneuerbaren Wasserstofferzeugung unter Berücksichtigung von Degradationsmechanismen
No full textMit der Transformation des Energiesystems zu einem höheren Anteil erneuerbarer Energiequellen (RES) arbeiten Elektrolyseure zunehmend unter variablen Lasten, wobei sie Teillastbetrieb, häufige Abschaltungen und Standby-Phasen ausgesetzt sind, welche die Degradation der Stacks beschleunigen, ihre Lebensdauer verkürzen und zusätzliche Unsicherheiten bei der Abschätzung der Wasserstoffproduktionskosten mit sich bringen. Um das zu berücksichtigen, wurde ein Degradationsmodell für Protonenaustausch-Membran (PEM) Elektrolyseure entwickelt, das sich auf die durch Abschaltungen und Standby verursachte Degradation fokussiert und weiters auf die techno-ökonomische Analyse von zwei Wasserstoffproduktionsszenarien in Österreich angewendet wurde: ein von der Verfügbarkeit erneuerbarer Energiequellen (RES) abhängiges Szenario (inputgesteuert), und eines, das einem bestimmten Wasserstoffbedarf folgt (nachfragegesteuert). Die Ergebnisse des inputgesteuerten Szenarios zeigen, dass die Profile der erneuerbaren Energieerzeugung einen starken Einfluss auf die Levelised Cost of Hydrogen (LCOH) haben, wobei windbetriebene Systeme die höchsten Volllaststunden und damit die niedrigsten Kosten erzielen. Im Gegensatz dazu führt der Betrieb mit PV-Energie zu einer begrenzten Auslastung und nicht wettbewerbsfähigen LCOH. Im nachfrageorientierten Szenario führen häufige Abschaltungen zu einer deutlichen Verkürzung der Stacklebensdauer und zu höheren Wasserstoffkosten, was die Wichtigkeit der Minimierung von Abschaltungen durch verbesserte Betriebsstrategien unterstreicht. Insgesamt zeigt diese Arbeit, dass die Berücksichtigung von Degradation in techno-ökonomischen Analysen für eine realistischere Bewertung der Performance und Kosten von Elektrolyseuren wesentlich ist. Die Ergebnisse unterstreichen die Notwendigkeit von Betriebsstrategien, die Degradation minimieren, und bilden eine Grundlage für zukünftige Ansätze, welche darauf abzielen, ein optimales Gleichgewicht zwischen Effizienz, Lebensdauer und Wirtschaftlichkeit grüner Wasserstoffsysteme zu bestimmen.With the transformation of the energy system towards a greater share of renewable energy sources (RES), electrolysers increasingly operate under variable loads, experiencing partial loading, frequent shutdowns and standby periods that accelerate stack degradation, reduce lifetime and introduce additional uncertainty in estimating hydrogen production costs. To address this, a degradation model for Proton Exchange Membrane (PEM) electrolysers, focusing on shutdown and standby related degradation, is developed and applied to the techno-economic assessment of two hydrogen production scenarios in Austria: one driven by RES availability (input-driven) and one following a specific hydrogen demand (demand-driven). The results of the input-driven scenario show that renewable generation profiles strongly influence the Levelised Cost of Hydrogen (LCOH), with wind powered systems achieving the highest full load hours and consequently the lowest costs. In contrast, PV powered operation leads to limited utilisation and uncompetitive LCOH. In the demand-driven scenario, frequent shutdowns significantly reduce stack lifetime and increase hydrogen costs, highlighting the importance of minimising shutdowns through improved operating strategies. Overall, this work demonstrates that accounting for degradation in techno-economic assessments is essential for a more realistic evaluation of electrolyser performance and cost. The findings underline the need for operating strategies that mitigate degradation and provide a basis for future approaches aiming to balance efficiency, lifetime and economic viability in green hydrogen systems
Integration und Inbetriebnahme des Pixelsensors RD50-MPW4 in das Caribou-Datenerfassungssystem
No full textZukünftige Hochluminositäts-Colliderexperimente erfordern Pixeldetektoren mit hoher räumlicher Auflösung, geringem Materialbudget und ausreichender Strahlenhärte. Monolithische aktive Pixelsensoren (MAPS), die Sensor und Ausleseelektronik auf einem einzigen Chip integrieren, stellen in diesem Zusammenhang eine vielversprechende Option dar. Innerhalb der CERN-RD50-Kollaboration ist der RD50-MPW4-Chip der neueste Prototyp in einer Serie von MAPS-Entwicklungen, die dieses Technologiekonzept für Tracking-Anwendungen untersuchen. Die moderne F&E zu Silizium-Trackingdetektoren stützt sich dabei auf flexible und wiederverwendbare Datenerfassungssysteme (DAQ), die Laborcharakterisierung und Betrieb in Teilchenstrahlen nahtlos verbinden. Das Caribou-Framework bietet hierfür einen einheitlichen Hard-, Firmware- und Software-Stack und wurde bereits für den Betrieb von RD50-MAPS-Devices eingesetzt. In dieser Arbeit wird der RD50-MPW4 auf eine neue Plattform migriert und vollständig in das Caribou-Framework integriert. Das resultierende Setup wird in mehreren Laboraufbauten validiert und anschließend unter realistischen Strahlbedingungen an der DESY-II-Elektronenanlage sowie im MedAustron-Krebstherapiezentrum getestet. Diese Messungen demonstrieren einen stabilen Betrieb innerhalb der Caribou-Umgebung bis an die durch den Sensor vorgegebenen Grenzen und gewährleisten die langfristige Wartbarkeit der Integration. Gleichzeitig leisten sie einen Beitrag zur Weiterentwicklung der nächsten Generation des Caribou-Frameworks.Future high-luminosity collider experiments require pixel detectors with high spatial resolution, low material budget and sufficient radiation tolerance. Monolithic active pixel sensor (MAPS), which integrate sensor and readout electronics on a single chip, are a promising option in this context. Within the CERN-RD50 collaboration, the RD50-MPW4 chip is the latest prototype in a series of MAPS devices developed to explore this technology for tracking applications. Modern silicon tracking R&D relies on flexible and reusable data acquisition (DAQ) systems to bridge laboratory characterization and beam test operation of such prototypes. The Caribou framework provides a unified hardware, firmware and software stack for this purpose and had previously been used to operate RD50 MAPS devices. In this thesis, the RD50-MPW4 is migrated to a new platform and fully integrated in the Caribou framework. The resulting setup is validated in several laboratory setups and is further tested under realistic beam conditions at the DESY II electron facility and the MedAustron cancer treatment center. These measurements demonstrate robust operation within the Caribou environment up to the limits imposed by the sensor and ensure the long term maintainability of the integration while contributing towards the next generation Caribou framework
Selbstkonsistente GW-Studie von topologischem a-Sn und Perowskit BiVO3
No full textCalculations on real materials provide valuable insight into their microscopic and macroscopic properties; not only their unperturbed state but under change of outside parameters, such as temperature, pressure or strain. As real materials contain a large number of particles, an exact solution is computationally infeasible. To address this challenge, sophisticated approximate methods must be developed. One such approach, is the GW method, which arises from perturbative treatment of the interaction. As an ab initio technique, GW requires only basic information about the system and a reasonable initial guess to begin the calculation. We apply the self-consistent GW method to two systems of interest: α-Sn and BiVO3.Tin in its low-temperature phase, α-Sn, exhibits intriguing topological properties, which have been extensively studied via angular resolved photoemission spectroscopy (ARPES) experiments and density functional theory (DFT). Using an exact two-component formalism for the Dirac Hamiltonian to capture the spin-orbit-coupling, our finite-temperature ab initio GW calculations of α-Sn under strain along the c-axis reveal features indicative of topological nature. Further, we find a possible high temperature phase in α-Sn.In contrast, BiVO3 has received limited attention to date, as it was only recently synthesized under high-temperature and high-pressure conditions using a diamond anvil cell. No experimental band structure is currently available, and previous computational studies have been focused on density functional theory (DFT), predicting an antiferromagnetic metallic phase. Our self-consistent GW analysis of BiVO3 indicates a significantly reduced metallically compared to these earlier predictions. We further determine the orbitals contributing to the antiferromagnetic state and confirm the stability of the a-type antiferromagnetic state in self-consistent GW
Analyzing the potential of ASCAT Surface Soil Moisture 6.25 km for drought monitoring over Mexico
No full textThis study assessed the potential of the ASCAT SSM 6.25 km product for agricultural drought monitoring across Mexico. The drought monitoring in Mexico currently relies on precipitation-based indices, without considering the use of in situ soil moisture observations and satellite-derived soil moisture products. To evaluate the performance, cross-validation was performed between ASCAT, ERA5-Land, and ESA CCI soil moisture products for assessing correlations under varying climatic and land cover conditions. Furthermore, drought indicators, including SMAPI and SPEI, were calculated and compared against the SPI from the Mexican Drought Monitor to evaluate the assessment during drought events. Results showed strong potential of ASCAT SSM in central and northeastern Mexico, while arid regions exhibited low correlation due to subsurface scattering effects. Otherwise, soil moisture anomalies derived from ASCAT aligned well with precipitation anomalies outside arid zones. In conclusion, ASCAT SSM 6.25 km demonstrates significant potential for integration into Mexico’s drought monitoring systems as drought indicators based on ASCAT effectively captured precipitation deficits and drought conditions, mirroring SPI patterns reported by national monitoring agencies
A New Addition to Global Soil Moisture Mapping: CFOSAT Scatterometer Algorithm Development and Validation
No full textThe monitoring of global soil moisture is crucial for understanding the hydrological cycle and managing terrestrial water resources. The China–France Oceanography Satellite (CFOSAT), equipped with the first sector-beam rotary scanning microwave scatterometer (CSCAT), provides a novel opportunity for global soil moisture mapping. However, the capability of CFOSAT’s Ku-band for soil moisture retrieval remains underexplored and lacks systematic evaluation. In this study, an Adaptive Backscatter Change Tracking (ABCT) algorithm is designed to retrieve absolute soil moisture from CFOSAT’s CSCAT measurements. The ABCT algorithm assumes a stable roughness, where changes in backscattering are primarily attributed to soil moisture variation based on a logarithmic relationship. It incorporates a vegetation influence coefficient, which quantifies how vegetation impacts the backscatter signal. This coefficient adaptively scales with changes in the Normalized Difference Vegetation Index to adjust the backscattering appropriately to include the effect of vegetation growth or decay. This allows the algorithm to isolate changes in the backscatter signal that are due to soil moisture while minimizing the false readings from vegetation growth or wilting. The CFOSAT ABCT algorithm’s performance was evaluated against extensive in-situ soil moisture data, demonstrating a robust correlation, with the Vertical-Vertical Polarization Ascending Orbit (VV Asc) result showing the highest accuracy, indicated by Pearson’s correlation coefficient (R) of 0.68 and unbiased root mean squared error (ubRMSE) of 0.057 m3/m3. Comparative analysis with the Advanced Scatterometer (ASCAT) data revealed that, while the ABCT algorithm’s correlation was slightly lower than that of the official EUMETSAT H SAF product, it notably improved the bias and ubRMSE metrics. This study underscores that the CFOSAT ABCT soil moisture retrieval algorithm and product are a valuable addition to global soil moisture mapping, complementing existing satellite missions or sensors such as SMAP, SMOS, ASCAT, AMSR2, and FY-3/MWRI
The role of social integration in the adverse effect of unemployment on mental health – Testing the causal pathway and buffering hypotheses using panel data
No full textSocial integration is considered crucially important for understanding the adverse effect of unemployment on mental health. Social integration is assumed to either bring about the health effects of unemployment (causal pathway hypothesis) or shield the unemployed from such effects (buffering hypothesis). However, there is scarce empirical evidence, especially based on panel data, regarding these two hypotheses. In our analysis, we use up to ten waves of the “Labour Market and Social Security” (PASS) German panel study and apply fixed effects panel regressions to account for unobserved confounders. We test several indicators that cover different aspects of social integration (numbers of strong and weak ties, conflict in the household, employed friends, general and job search-specific social support). We find no empirical support for the causal pathway hypothesis and only very limited support for the buffering hypothesis
PEMANFAATAN KAPAL KARAM SEBAGAI DESTINASI SELAM DALAM KAIDAH CAGAR BUDAYA BAWAH AIR
No full textIndonesia adalah negara kepulauan terbesar di dunia. Dua pertiga wilayahnya adalah laut.
Pembangunan pariwisata yang berkelanjutan berbasis bahari dilakukan dengan upaya sinergi dengan
membangun budaya maritim dan memperkuat budaya bahari dalam pemanfaatan dan pengelolaan sumber
daya kelautan. Permasalahan yang ditimbulkan saat ini terhadap kondisi ekosistem terumbu karang
sebagai akibat destinasi selam semakin memburuk akibat tingkat laku manusia itu sendiri. di sisi lain
sumber daya tinggalan budaya bawah air belum optimal dimanfaatkan, bahkan seringkali diambil secara
ilegal. Indonesia sangat kaya akan Benda Muatan Kapal Tenggelam (BMKT) sebagai peninggalan
Arkeologi Bawah air. Berbagai aktivitas budaya dan perdagangan maritim telah meninggalkan data yang
melimpah untuk merekonstruksi peradaban bangsa ini. Kenyataanya adalah upaya untuk merekontruksi
masih menghadapi banyak tantangan terutama perbedaan dalam hal sudut pandang dalam pengelolaan
Benda Muatan Kapal Tenggelam tersebut oleh berbagai pihak. Ketersediaan sumber daya Tinggalan
bawah air seperti kapal-kapal karam dan menurunya kualitas terumbu karang dapat dimanfaatkan sebagai
daya tarik wisata selam, sekaligus upaya terhadap pelestarian warisan budaya bahari
The Collaborative (Re)turn: Next-Gen Methodologies in Women’s Architectural Histories
No full textThe last few years have witnessed a notable rise in collaborative initiatives to increase knowledge about the histories of women architects. These initiatives range from team-based writing projects to exhibitions, symposia, databases, and more. Such efforts harken back to feminist practices of the 1970s, 1980s, and 1990s, which broke new ground in raising awareness of women in architecture. In this chapter, I offer a brief survey of earlier collaborative approaches to women’s architectural histories, consider the renewed interest in such methods, and weigh the opportunities and challenges posed by this (re)turn to team-based initiatives