Transition metal oxide coupling with carbon is an effective method for improving electrical conductivity of battery electrodes and avoiding the degradation of their lithium storage capability due to large volume expansion/contraction and severe particle aggregation during the lithium insertion and desertion process. In our present work, we develop an effective approach to fabricate the nanocomposites of porous rod-shaped Fe₃O₄ anchored on reduced graphene oxide (Fe₃O₄/rGO) by controlling the in situ nucleation and growth of β-FeOOH onto the graphene oxide (β-FeOOH/GO) and followed by dielectric barrier discharge (DBD) hydrogen plasma treatment. Such well-designed hierarchical nanostructures are beneficial for maximum utilization of electrochemically active matter in lithium ion batteries and display superior Li uptake with high reversible capacity, good rate capability, and excellent stability, maintaining 890 mA h g⁻¹ capacity over 100 cycles at a current density of 500 mA g⁻¹.

Future high-capacity wireless communications will extensively use the broad bands still available millimeter-wave frequencies. Channels with bandwidth broader than those in use today will guarantee enhanced data-rate and reduced latency performance. The recent progress of integrated-circuit semiconductor technologies finally allowed the design of reliable electronics operating at millimeter-wave frequencies. On top, advanced Fully Depleted Silicon On Insulator (FD-SOI) Complementary Metal Oxide Semiconductor (CMOS) and Silicon Germanium (SiGe) Bipolar CMOS (BiCMOS) processes enabled to co-integrate large digital blocks with frontends operating at tens or hundreds of GHz. The current under-deployment fifth-generation mobile-communication standard (5G) takes advantage of these advancements, massively exploiting the frequency bands from 24 GHz to 100 GHz. Furthermore, besides enlarging the channel bandwidth, improvements of the signal-to-noise power ratio (SNR) at the receiver input, combined with Multiple-Input Multiple-Output (MIMO) techniques provide an additional boost to the communication data-rate. Both approaches require arrays of antennas, plus electronic beam-steering which becomes essential in the case of moving transmitting-receiving pairs. Finally, social, economic, historical, and technological trends indicate that future wireless standards will require data-rates, latencies, and density of served users per square kilometer well beyond those offered by the 5G. Envisioned to be deployed towards the end of this decade, the six mobile communication standard (6G) will win future challenges thanks to the very ultra-broad bands available from 100 GHz until the tens of THz. Basic research is hence needed to address the open challenges necessary to reach the goals of future wireless communication systems, such as bandwidth and frequency operation factor-10 increase or power consumption reduction against the actual state of the art. This Habilitation thesis proposes circuit theory and concepts up to feasibility study of circuit implementation and experimental characterization in the laboratory of transceiver electronics for future high-capacity communications useful for the knowledge gain necessary for the conception of future communication systems. In detail, basic scientific research to understand the operation of millimeter-wave communication circuits implemented in 22 nm FD-SOI CMOS and 130 nm SiGe BiCMOS technologies has been performed.

Untersucht wird die Kapazität von Nebenströmen auf Knotenpunkten, die - mit dem Verkehrszeichen 301 bzw. 306 sowie dem Verkehrszeichen 205 geregelt werden, - keine abknickende Vorfahrt aufweisen, - auf zweistreifigen Stadtstraßen liegen und - eigene Fahrstreifen für Linksabbieger auf der Hauptstraße besitzen. Aufbauend auf vorhandenen Untersuchungen werden Auswirkungen von Fahrzeugstrom- und Straßencharakteristiken auf die Kapazität von Nebenströmen sowie verschiedene Aspekte des unmittelbaren Verkehrsablaufs auf Vorfahrtknoten analysiert. Fahrzeugstrom- und Straßencharakteristiken, die zu einer verstärkten Pulkbildung in übergeordneten Fahrzeugströmen führen, ziehen im Vergleich mit zufälligem Verkehrsfluss eine Kapazitätserhöhung nach sich. Mit Hilfe eines erstellten Bewertungsschemas ist es möglich, die Auswirkungen auf die Kapazität von Nebenströmen zu quantifizieren. Um die Interaktionen zwischen einander untergeordneten Fahrzeugströmen bei der Kapazitätsberechnung zu berücksichtigen, werden - die Wahrscheinlichkeit für rückstaufreien Zustand, - die Zusammensetzung des Hauptstroms von kreuzenden Fahrzeugen und Linkseinbiegern sowie - die Berechnung der Kapazität von Mischströmen mit Hilfe von Simulationen untersucht. Zur Berechnung der Wahrscheinlichkeit für rückstaufreien Zustand wird ein vereinfachtes Verfahren dargelegt, das auf bereits vorhandene Arbeiten aufbaut. Für die Zusammensetzung des Hauptstroms von kreuzenden Fahrzeugen und Linkseinbiegern werden die Ansätze aus früheren Untersuchungen präzisiert, indem die Interaktionen zwischen einander vorfahrtrechtlich untergeordneten Fahrzeugströmen stärker berücksichtigt werden. Eine Präzisierung erfährt ebenfalls der Ansatz für die Berechnung der gemeinsamen Kapazität von Mischströmen in Nebenstraßenzufahrten. Hierbei wird gezeigt, dass die gegenseitigen Behinderungen von Fahrzeugen innerhalb von Mischströmen, im Vergleich mit dem bisherigen Ansatz, zu einer niedrigeren gemeinsamen Kapazität führen.

We introduce and demonstrate a simple and efficient method for simulating mixtures of legacy and autonomous trains. The method generalises an earlier simulation that we developed for legacy-only operations, in which trains run according to fixed-block signalling rules. Autonomous trains, which use moving-block signalling rules, are incorporated into this framework by employing an overlapping set of short virtual fixed-blocks. Safe occupancy is then maintained by using shadowing rules that link the two sets of blocks. The paper gives relevant rail background, details of the proposed simulation rules, and demonstrates exemplar solution trajectories. The simulation technique is validated both in terms of maintaining safe occupancy and providing a close approximation of the true continuous-space dynamics of autonomous leader-follower pairs. At the Dresden meeting, a variety of interesting mixed-fleet capacity results will also be presented.

Connected and automated vehicles (CAVs) will behave fundamentally differently than human drivers. In mixed traffic, this could lead to inefficiencies and safety-critical situations since neither human drivers nor CAVs will be able to fully anticipate or predict surrounding traffic dynamics. Thus, some researchers proposed to separate CAVs from conventional vehicles by dedicating exclusive lanes to them. However, the separation of road infrastructure can negatively impact the system’s capacity. While the effects of CAV lanes were addressed for freeways, their deployment in urban settings is not yet fully understood. This paper systematically analyzes the effects of CAV-lanes in an urban setting accounting for the corresponding complexities. We employ microscopic traffic simulation to model traffic flow dynamics in a detailed manner and to be able to consider a wide array of supply-related characteristics. These concern intersection geometry, public transport operation, traffic signal control, and traffic management. Our study contributes to the existing literature by revealing the potential of CAV lanes in an urban setting while accounting for the behavioral and topological complexities. The results of this study can support decision-makers in the design of future urban transportation systems and to prepare cities for the upcoming era of automation in traffic.

Die Hebammenstudie Sachsen des IGES-Institutes aus dem Jahre 2019 kam im Ergebnis dazu, dass die Versorgung mit Hebammenleistungen in Sachsen zwar gesichert, in speziellen Bereichen aber durchaus gefährdet sein könnte. Deshalb wurden in der Hebammenstudie 14 Handlungsempfehlungen abgeleitet, zu denen der vom Sozialministerium geführte Umsetzungskreis in seinem vorgelegten Bericht Stellung nimmt. Redaktionsschluss: 20.07.2022

The properties of ferroelectric materials, which were discovered almost a century ago¹ , have led to a huge range of applications, such as digital information storage² , pyroelectric energy conversion³ and neuromorphic computing⁴⁻⁵ . Recently, it was shown that ferroelectrics can have negative capacitance⁶⁻¹¹, which could improve the energy efficiency of conventional electronics beyond fundamental limits¹²⁻¹⁴. In Landau–Ginzburg–Devonshire theory¹⁵⁻¹⁷, this negative capacitance is directly related to the doublewell shape of the ferroelectric polarization–energy landscape, which was thought for more than 70 years to be inaccessible to experiments¹⁸. Here we report electrical measurements of the intrinsic double-well energy landscape in a thin layer of ferroelectric Hf₀.₅Zr₀.₅O₂. To achieve this, we integrated the ferroelectric into a heterostructure capacitor with a second dielectric layer to prevent immediate screening of polarization charges during switching. These results show that negative capacitance has its origin in the energy barrier in a double-well landscape. Furthermore, we demonstrate that ferroelectric negative capacitance can be fast and hysteresis-free, which is important for prospective applications¹⁹. In addition, the Hf₀.₅Zr₀.₅O₂ used in this work is currently the most industry-relevant ferroelectric material, because both HfO₂ and ZrO₂ thin films are already used in everyday electronics²⁰. This could lead to fast adoption of negative capacitance effects in future products with markedly improved energy efficiency.

The Rayleigh law describes the linear dependence of the permittivity of a ferroelectric on the applied ac electric field amplitude due to irreversible motions of domain walls. We show that this gives rise to a new equivalent-circuit element predestined to fit the impedance spectra of ferroelectrics based on an accepted physical model. Such impedance spectroscopy is a powerful tool to obtain a dielectric and resistive representation of the entire sample structure. The superiority of the Rayleigh analysis based on impedance spectroscopy compared to the common single-frequency approach is demonstrated for a ferroelectric Si : HfO₂ thin film

Current commercial intercalation cathodes are approaching their theoretical capacity edges, which limits further improvement of the energy density in Li-ion batteries. To overcome this limitation, Li-rich antiperovskite cathodes were developed, utilizing both cationic and anionic redox activities. This class of materials has the general formula (Li2TM)ChO, where TM and Ch represent a transition metal (Fe, Mn, Co) and chalcogen ion (S, Se), respectively. This work focuses on understanding the reaction mechanism, exploring novel approaches for optimizing the electrochemical performance, and developing a scalable synthesis method for the antiperovskite cathodes. Firstly, the effect of substituting S by Se in the solid-state synthesized (Li2Fe)SO on the structural and electrochemical performance is thoroughly investigated. The anionic substitution was found to improve the structural and thermal stabilities of (Li2Fe)SO material. The cyclic voltammetry data confirmed both the cationic (Fe) and anionic (S/Se) redox activities, with possibility of controlling the anionic redox potential through the anionic substitution. It was observed that the electrochemical performance exhibits a non-linear dependence on the degree of anionic substitution. Among the prepared (Li2Fe)S1-xSexO (x = 0.1-0.9) compositions, (Li2Fe)S0.7Se0.3O exhibited the best electrochemical performance with a specific capacity 245 mAhg-1 and good cycling stability at low current rate. Ex-situ and in-situ measurements suggested an enhanced structural stability of (Li2Fe)S0.7Se0.3O during electrochemical cycling compared to (Li2Fe)SO, which could be one of the reasons for its superior performance at low current rates. The second part of this work focuses on understanding the reaction mechanism of (Li2Fe)SeO prepared by solid-state reaction (SSR) method and exploring the impact of cationic substitution of Fe by Mn on its structural and electrochemical properties. Electrochemical investigations showed that the cationic redox activity leads to a reversible cycling behaviour, indicating its role in the stable performance. Whereas, the anionic redox activity leads to partial decomposition of the (Li2Fe)SeO cathode to an electrochemically active phase. In general, although the electrochemical activity of the phase resulting from the partial decomposition of any antiperovskite composition can compensate the initial capacity loss, it opens a channel for capacity fading over long term of cycling. The (Li2Fe)SeO cathode could deliver an initial specific discharge capacity of 165 mAhg-1, which declined to only 140 mAhg-1 after 100 cycles, indicating a good cycling performance. Even at high current rate (1C), the (Li2Fe)SeO could provide a reasonable specific capacity of 100 mAhg-1. Replacing Fe with Mn reduced the overall redox activity of the cationic and anionic redox processes, when using active material: carbon: binder weight ratio of 70:15:15 wt. %. This may result from impeded kinetics and the Jahn-Teller effect associated with Mn2+/3+ redox. However, low substitution levels can be beneficial in optimizing the performance while minimizing the negative effects associated with Mn2+/3+ redox pair. Modifying the electrode ratio to 85:10:5 wt. % improved the specific capacity for (Li2Fe0.9Mn0.1)SeO, surpassing that of the unsubstituted (Li2Fe)SeO cathode. These findings highlight the role of controlled substitution and electrode ratio in optimizing the electrochemical performance of antiperovskite cathodes. The third part of this work focuses on developing scalable, controllable, and sustainable synthesis of antiperovskite cathodes using mechanochemical (MC) method based on ball milling (BM), which is crucial for practical application. Both (Li2Fe)SeO and (Li2Fe)SO antiperovskite cathodes have been successfully prepared by direct MC without the need for external heating, which is advantageous for energy saving. Post-heat treatment after the milling was found to be an effective strategy for controlling the morphological and electrochemical properties of both materials. Both ball-milled materials revealed similar reaction mechanism to the (Li2Fe)SeO prepared by SSR method, involving both cationic and anionic redox activities. The ball-milled (Li2Fe)SeO displayed an average specific discharge capacity of 255 mAhg-1 at 0.1C and 138 mAhg-1 at 1C in the potential range 1-3 V. Transmission electron microscopy and magnetic investigations revealed a partial conversion of the mechanochemically synthesized (Li2Fe)SeO into an electrochemically active Fe1-xSex phase during the anionic redox process. On the other hand, mechanochemically synthesized (Li2Fe)SO exhibited an average specific discharge capacity of 340 and 133 mAhg-1 at 0.1C and 1C, respectively, in the potential range 1-3 V. Excluding the anionic redox activity of both materials by restricting the potential scanning range was found to be advantageous for enhancing the cycling stability over long range of cycling. This highlights the critical role of controlling the potential range on the electrochemical performance and cyclability of these materials.

Ziel dieser Studie, die auf Anregung des BUND entstand, ist es, zu fünf Fragen Stellung zu nehmen, die für die Gestaltung einer nachhaltigen und effizienten Luftverkehrsentwicklung in Deutschland wichtig sind. 1. Welche Kapazität haben die Bahnensysteme der drei großen Flughäfen Berlin (BER), München und Düsseldorf? Müssen diese Flughäfen um weitere Bahnen vergrößert werden oder reicht ihre Kapazität aus? 2. Welche flughafenrelevanten Trends bestimmen den Luftverkehr in Deutschland? Muss man den aktuellen Forderungen der Luftverkehrswirtschaft folgen oder gibt es auch Anzeichen für alternative Entwicklungen, die nachhaltiger sind und zu effizienteren Lösungen führen? 3. Wie gut und verlässlich sind Prognosen der Luftverkehrswirtschaft? Muss man diese Prognosen hinnehmen oder gibt es Anhaltspunkte dafür, dass sie systematisch unzuverlässig sind? 4. Wie sind die wirtschaftlichen Perspektiven der Flughäfen? Warum erzielen so viele Flughäfen Verluste? Was kann getan werden, um die Verluste zu verringern? 5. Welche Erfahrungen gibt es mit Flughafenkooperationen? Müssen Flughäfen immer alleinstehende Unternehmen darstellen oder gibt es Beispiele für gelungene kooperative Lösungen? Die Studie beleuchtet historische Erfahrungen, stellt aktuelle Entwicklungen vor und zieht Schlussfolgerungen für eine zukunftsfähige Luftverkehrspolitik in Deutschland. Drei wesentliche Aspekte dabei sind eine marktgerechte Internalisierung externer Effekte des Luftverkehrs, eine verstärkte Kooperation von Flughäfen in Deutschland und eine weitere Marktöffnung des deutschen Marktes für ausländische Wettbewerber. Großer Dank wird den Mitgliedern der Forschungsgruppe Luftverkehr geschuldet, die wertvolle Informationen beigetragen haben, ohne die diese Studie nicht hätte entstehen können. / The aim of the study is to discuss five aspects of the German aviation system which are debated intensely in Germany. The first aspect is the problem of the capacity of airports. There are several airports with two runways. The question arose what is the capacity of these airports? Some wanted to add third ones to cope with future growth while others argued the capacity would be sufficient for the foreseeable future. This leads to the second aspect which covers the trends that dominate the further development of the German aviation markets. The latter will be shaped by the competition between various airlines and various airports. Especially important will be the new competition between old airports in Europe and new ones in Istanbul, Dubai or Abu Dhabi. Equally important is the question, how good forecasts of future growth of airports are (third aspect). Studies delivered by airports themselves show a systematic overestimation of their own growth. This leads to the fourth aspect, i.e. to the question of the economic situation of small and large airports in Germany. We have to ask, why there are so many small airports with losses. Last but not least the following topic has to be discussed: could more cooperation between large and small airports solve the difficult economic situation of the small ones without hindering the large ones? International examples are being analysed. The study concludes with a proposal for the further development of the German aviation system.