We present the mission proposal for a spaceborne multi-frequency lidar that is able to perform simultaneous Doppler Rayleigh, Mie and resonance measurements to gain temperature and wind data from ground to thermosphere. The suitability of the technology is demonstrated with a novel ground-based lidar with a diode-pumped alexandrite laser that acts as a unit for a lidar network able to cover the atmosphere up to 100 km over a large area at day- and nighttime in polar regions. The performance of a spaceborne lidar at the iron resonance line at 386 nm is derived from simulations with parameters similar to Aeolus. The multi-frequency lidar achieves the same resolution and uncertainties in wind measurements as Aeolus but additionally provides the wind and temperature up to 120 km. The reduction of the solar background by three to five orders of magnitude by means of the usage of narrow bandwidth filters and laser allows for significantly lower laser pulse energies (~ 10 mJ) and higher repetition rates (~500 Hz). Thereby the laser as a key-component and with the highest risk of failure is reduced in complexity, as no amplification stages are necessary to yield the high pulse energy. The roadmap to space is discussed in light of the heritage from Aeolus and with the diode-pumped alexandrite laser that is in line with the FULAS (Future Laser System) platform that is also the basis for the emitter of Merlin. The necessary development steps are identified and the current activities to address them are described.
Im Zuge der Energiewende ergibt sich durch die steigende Integration von leistungselektronisch gekoppelten Anlagen, wie z. B. PV, Wind oder Batteriespeicher, eine starke Durchdringung der Stromnetze mit Wechselrichtern. Für die Gewährleistung einer hohe Spannungsqualität spielen Wechselrichter daher eine zunehmend wichtige Rolle. Dieses Buch widmet sich der Analyse von Resonanzen in Stromnetzen mit hohem Leistungselektronikanteil und vermittelt neue Ansätze für die Oberschwingungsbewertung von Wechselrichtern. Dazu wird mit der differentiellen Impedanzspektroskopie ein messtechnisches Verfahren vorgestellt, mit dem sich Wechselrichter als frequenzabhängige Ersatzspannungsquelle mit Innenimpedanz (Thévenin-Äquivalent) darstellen lassen. Anhand von exemplarischen Messergebnissen werden die relevanten Ursachen von wechselrichterinternen Oberschwingungsquellen aufgezeigt. Ferner werden die Einflussfaktoren auf die wirksame Wechselrichterimpedanz beschrieben. Insbesondere der Wechselrichterregelung kommt hierbei eine zentrale Bedeutung zu. Der Anwendungsnutzen wird u. a. durch ein Praxisbeispiel gezeigt, bei dem auftretende Resonanzen durch Software-Änderungen vermieden werden können.
From 1990 to 2018, the share of greenhouse gas (GHG) emissions caused by passenger vehicles in the EU increased from about 9% to 14%. Thus, urgent action is required to reduce the GHG emissions of passenger vehicles. Battery electric vehicles (BEV) are a promising option to reduce GHG emissions for passenger vehicles. In this paper, we analyze the GHG emissions and the electricity demand for a BEV over the entire life cycle. We consider the production, utilization and disposal in the current energy system and in a renewable energy system. In both cases, wind electricity is considered for the utilization phase. In the renewable energy system, renewable electricity is applied in the entire supply chain. This also includes the production of materials from hydrogen produced in an electrolysis. The hydrogen is for example used as reducing agent in steel production as well as converted with CO2 to chemicals and fuels. We integrate the renewable production processes in a database together with the LCA database ecoinvent 3.7. Through the transition from the current energy system to the renewable energy system, the GHG emissions over the entire life cycle decrease from 60 to 5 g CO2-eq/km. The total electricity demand increases from 0.2 to 0.41 kWh/km. The majority of electricity is required in the production phase.