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Cross-disciplinary concept borrowing : a critical revision of a robustness analysis for automatic emotion recognition in conversations
No full textAffective computing is an inherently interdisciplinary field, drawing knowledge from diverse disciplines such as psychology, neuroscience, sociology, and cultural studies. Typically, this knowledge is adopted pragmatically and action-oriented to inform research in the field. This paper critically examines a robustness analysis in affective computing to explore the conceptual borrowing of terms, theories, and methods from these reference disciplines. It highlights the challenges when knowledge from fields with differing foundations - such as the humanities and social sciences - is integrated into computer science. The paper argues that these disciplinary differences, especially in terms of research practices and theoretical frameworks, can lead to misunderstandings and simplification during the appropriation process, potentially limiting the effectiveness and accuracy of affective computing systems.PeerReviewe
Trade-offs among SDGs : how the pursuit of economic, food, and urban development goals may undermine climate and equity targets?
No full textThe United Nations Sustainable Development Goals (SDGs) provide a comprehensive framework for addressing global challenges; however, their implementation reveals critical tensions between development priorities and climate action that warrant deeper examination. Indeed, one significant factor impacting the implementation of the SDGs is the presence of conflicts between certain goals. Accordingly, this study aims to critically examine how the pursuit of economic growth (SDG 8), food security (SDG 2), clean energy (SDG 7), and urban development (SDG 11) may exacerbate climate change and environmental degradation (SDGs 13–15) while also reinforcing social inequalities (SDGs 6, 10). Employing a review-based approach to assess SDG interactions—focusing on the climate-development nexus, particularly the relationship between economic expansion (SDG 8), environmental sustainability (SDGs 13–15), and social equity (SDGs 1, 5, and 10)—this research identifies key areas of conflict that challenge the framework's internal coherence. Findings indicate significant trade-offs between economic growth and environmental sustainability, alongside previously underexamined tensions between social equity goals and resource-intensive development strategies. Accordingly, the study proposes a roadmap for resolving these tensions through integrated climate governance, targeted interventions, and cross-sectoral decision-making that aligns development with the Paris Agreement and the 2030 Agenda. The practical implications of the study are twofold. First, it triggers a reflection on the root causes of conflicting goals, a serious problem that has been largely overlooked. Second, it highlights the importance of addressing the need to pay more attention to existing conflicts, as they have adverse effects that should be avoided. By offering actionable recommendations, this study contributes to the evolving discourse on sustainable development within the context of climate change mitigation and adaptation. It provides a strategic pathway toward balancing economic development with environmental resilience, ensuring that SDG implementation aligns with the urgent need for climate action within the remaining timeframe before 2030.PeerReviewe
„Wir haben keine Wahl. Die Polizei ist Teil unseres Arbeitsfeldes.“ [: Tilman Lutz im Gespräch mit Malte Block]
No full textMalte Block, Leiter des „KIDS - Anlaufstelle für junge Menschen in besonderen Lebenslagen“ in Hamburg im Gespräch mit Tilman Lutz: Ausgangspunkt des Gesprächs ist die Ausgestaltung der zwangsläufigen Begegnungen mit der Polizei und der Umgang mit institutionellen Schnittmengen in der Arbeit des KIDS. Dabei wird deutlich, wie im Spannungsfeld zwischen Kontrolle, Prävention und Schutzraumgestaltung navigiert wird und welche Strategien entwickelt werden, um trotz struktureller Zielkonflikte handlungsfähig zu bleiben.AlternativeReviewe
Grüner Wasserstoff für die Energiewende : Potentiale, Grenzen und Prioritäten ; Teil 6: Wasserstoffanwendungen im Sektorenvergleich
Get PDFDieser zusammenfassende Studienteil 6 basiert auf den vorherigen Teilen 1 bis 5 der Studienreihe "Grüner Wasserstoff für die Energiewende-Potentiale, Grenzen und Prioritäten" und bewertet die Priorisierung der Nutzung von grünem Wasserstoff in drei Sektoren: Industrie, Wärme und Verkehr. Aus Effizienzgesichtspunkten ist die Nutzung von grünem Wasserstoff im Industriesektor gegenüber Wärme und Verkehr zu priorisieren. Industriegüter, wie Primärstahl, Kupfer, Ammoniak, Methanol und Raffinerieerzeugnisse, die schwer zu defossilisieren sind, können von grünem Wasserstoff profitieren. Allerdings ist die Wettbewerbsfähigkeit des Einsatzes von grünem Wasserstoff in der Industrie nur bei sehr niedrigen Bezugspreisen bzw. Herstellungskosten erreichbar. Die Herstellungskosten liegen bei 6,07 bis 9,65 €/kg (netto, ohne MWSt.). Wettbewerbsfähig wäre die Produktion von Primärstahl bei einem Preis für grünen Wasserstoff von ca. 1,6 €/kg (netto, ohne MWSt.) und für die Produktion von Ammoniak läge der Grenzpreis für grünen Wasserstoff bei ca. 3,3 €/kg (netto, ohne MWSt.). Im Wär-mesektor ist grüner Wasserstoff derzeit ebenfalls keine konkurrenzfähige Alternative zu Erdgasheiz-kesseln, Wärmenetzen oder Wärmepumpen, denn der Grenzpreis für grünen Wasserstoff läge hier bei sehr niedrigen ca. 4 €/kg (brutto, inkl. MWSt.). Auch die im Vergleich zur direkten Stromnutzung in Wärmepumpen schlechte Effizienz spricht gegen eine breite Anwendung von Wasserstoff für die Wär-mebereitstellung, da Wärmepumpen bis zu sechsmal weniger Strom benötigen als Heizsysteme auf Basis von mit grünem Strom erzeugten Wasserstoff. Dennoch ist die Nutzung von grünem Wasserstoff für weniger kostensensible Nischenanwendungen wie die Spitzenlastdeckung in Wärmenetzen denk-bar und die Einbindung der Abwärme aus Elektrolyseuren und Brennstoffzellen wäre als ergänzendes Geschäftsmodell der Wasserstofferzeugung und-nutzung vorteilhaft. Im Verkehrssektor ist Wasserstoff im Vergleich zu fossilen Kraftstoffen bereits bei Preisen von ca. 13 €/kg (brutto, inkl. MWSt.) und im Vergleich zu Elektrofahrzeugen bei ca. 9 €/kg (brutto, inkl. MWSt.) wettbewerbsfähig. Das politische Instrument der THG-Minderungsquote ermöglicht daneben zusätzliche Einnahmen für die Wasser-stoffnutzung im Verkehrssektor. Wasserstoff sollte wegen der schlechteren Energieeffizienz im Ver-gleich zum rein elektrischen Antrieb aber vorzugsweise in zeit-, gewichts-und/oder volumensensiblen Nischen zur Anwendung kommen. Der Sektorenvergleich zeigt zwei gegenläufige Trends bei der Nutzung von grünem Wasserstoff. Während Effizienzüberlegungen nahelegen, den Industriesektor zu priorisieren, würde bei einem reinen Kostenvergleich mit fossilen Brennstoffen der wettbewerbsfähige Einsatz zuerst im Verkehrssektor möglich werden. Daraus ergibt sich die Notwendigkeit einer strategischen Planung und politischer Unterstützung zur Maximierung der erreichbaren Senkung von Treibhausgasemissionen durch den Einsatz von (knappem) grünem Wasserstoff in den verschiedenen Verbrauchssektoren.Bundesministerium für Wirtschaft und EnergieNonPeerReviewe
Numerical and analytical takeoff field length calculations for jet aircraft
Get PDFPurpose – The greater of two distances (Balanced Field Length or Takeoff Distance +15%) results in the Takeoff Field Length (TOFL). The TOFL is a takeoff distance with safety margins according to Certification Standards for Large Aeroplanes by EASA (CS-25) and FAA (FAR Part 25). Simple analytical approximations for the TOFL are checked against more demanding numerical simulations to determine the validity of the simple solutions and to implement adjustments for them as necessary. --- Methodology – The differential equation of the aircraft's acceleration is solved in MATLAB together with varying engine failure speeds. Analytical calculations of the Balanced Field Length by Torenbeek, Kundu, and Loftin are investigated. This includes the evaluation of statistical data. --- Findings – Analytical approximations deviate by 0.1% to 28.2% from the numerical solution. The most accurate analytical approximation is the simple method proposed by Loftin based on statistics. It shows deviations of less than 5.4%. The results confirm that the TOFL for jets with four engines is determined by the Takeoff Distance +15%, while for jets with two engines, the Balanced Field Length is decisive for TOFL. --- Research limitations – Simplifying assumptions had to be made e.g. regarding rotation time and speed, flap geometry, and asymmetric drag. While ground distances were solved numerically from acceleration and deceleration, air distance and rotation distance had to be determined analytically. --- Practical implications – A reliable and tested analytical procedure is useful for quick aircraft performance estimates and to include an inverse TOFL method into aircraft preliminary sizing. --- Originality – This seems to be the first report to provide a systematic check of available analytical approximations for the TOFL in comparison with a numerical solution.NonPeerReviewe
Identifying wave drag for the generic drag polar equation : unveiling polars of 16 passenger aircraft
Get PDFPurpose – This work systematically derives the best form of a generic drag polar equation together with the optimum numerical values of its parameters to unveil the drag coefficient of 16 passenger aircraft as a function of lift coefficient and Mach number. The parameters are selected such that they can be estimated also for other aircraft mainly from their geometry. --- Methodology – Drag polars in graphical form from Obert (2009) are the starting point. Numerical values of the drag coefficient are obtained with the WebPlotDigitizer. In the generic equation, zero lift drag is assumed constant, the term representing induced drag is taken from Nita (2012). For the wave drag term, seven functions of Mach number are investigated. The difference between Mach number and critical Mach number to the power of 4 is the classic approach based on Lock (1951). Two more general power functions, tan, tanh, sinh, and an exponential function are looked at. Parameters are optimized by minimizing the Root Mean Squared Percentage Error (RMSPE). Optimization is done with the Solver in Excel using the Generalized Reduced Gradient (GRG2) code supplied by Frontline Systems. --- Findings – Based on all 16 investigated aircraft, a generic drag polar using the hyperbolic tangent (tanh) to express wave drag is best with mean RMSPE of only 0.68%. The second best is the most general power function with mean RMSPE of 0.75%. Its special case, the often quoted but unflexible function from Lock comes out last here with a mean RMSPE of 0.95%. Nevertheless, all seven functions can be used to represent wave drag. The zero lift drag coefficient is identified between 0.013 (B777) and 0.020 (A320). The Mach dependence of the drag coefficient comes not only from wave drag, but also from induced drag and its Mach dependence beyond 0.3 Mach. Calculated parameters are plausible and come close to reference values from literature. --- Research Limitations – Aerodynamic data is generally confidential. Therefore, public drag data is limited. The extension of the method to other aircraft yields a drag estimate. --- Practical Implications – The generic equation can be used in preliminary aircraft design as well as in calculations in aircraft performance and flight operations. --- Originality – This project formulates a generic drag polar equation with a choice of new wave drag terms some based on a historic precursor. The new approach with a hyperbolic tangent function is recommended.NonPeerReviewe
Lower risk approach for low emission passenger aircraft : combined LH2 and kerosene propulsion
Get PDFResearch question: Airbus proposed "ZEROe" based on "disruption" and "giant leaps" but failed. Main argument: The hydrogen infrastructure at airports is not ready. What are the lessons learned? --- Idea: Instead, the idea is to use a conventional A320 type aircraft driven by conventional turbofan engines. 20% of the fuel tank's kerosene energy is substituted by LH2. As such, the volume of the additional LH2 tanks needed is minimized and can easily be integrated. The engine only needs a combined kerosene/LH2 combustor. This minimizes new technology needs and risks and stays within established experience with turbofan engines. Reliability, performance, engine life, and maintenance procedures stay the same. Emergency thrust requirements and thrust response times can be fulfilled. For a standard 900-nm-mission, CO2 emissions are reduced by approximately 50%. From airports without LH2 infrastructure, aircraft can operate with kerosene. In contrast to full hydrogen airplanes, this concept has no infrastructure limitations. --- Findings: Fuselage mounted LH2 tanks are possible as well as roof mounted tanks. The latter have the advantage that the LH2 tanks are located outside of the pressure cabin and not too far aft (CG). In case of a fire, hydrogen flames would rise away from cabin and occupants. To replace 20% of the kerosene by LH2 fuel of the same energy, the LH2 tank volume is approximately 20 m³. For each flight, the LH2 tanks are filled completely. For the missing energy for the flight, kerosene is used. Consequently, the shorter the mission, the higher the CO2 reduction. For a standard 900-NM-mission CO2 savings are about 50%. This reduces to about 15% when all tanks are full. Necessary is a dual fuel system and dual fuel combustor arrangements (staged or combined fuel injection). --- Summary: Combined kerosene and LH2 combustion could be a viable step to reduce CO2 emissions for passenger aircraft.NonPeerReviewe
Active power control of multi-rotor turbines for fast frequency reserve
Get PDFFast frequency reserve is a dynamic ancillary service for the power grid. In previous grids, this was provided by power plants with synchronous machines and dispatchable primary sources. In systems of the near future, this must be provided as far as possible by converter-based regenerative resources. The requirements for wind energy systems are high. According to existing grid codes, output must be reduced by 60–80% within 1–2 seconds to provide so-called negative inertia. Positive inertia, i.e., an increase in power to emulate the inertia of conventional synchronous machines, results from the power reserve of a derated wind energy system. To be able to provide this with a multi-rotor wind turbine, i.e., the primary energy system of a wind energy system, the established control concepts must be significantly modified. This article presents a decentralised control concept in which each rotor contributes to the active power fed into the grid. A theoretical and systematic controller design method is proposed, which allows the dynamic adaptation of the power generated by wind power plants. The focus is on the dynamic tracking control of the primary power. Finally, simulation results are presented, along with a concept that enables active power generation also by turbine rotors without pitch control via stall operation.NonPeerReviewe