不伦瑞克技术大学

A central question for understanding interplanetary coronal mass ejection (ICME) physics and improving space weather forecasting is how ICMEs evolve in interplanetary space. We have updated one of the most comprehensive in situ ICME catalogs to date, which now includes 1976 events from 11 space missions covering over 34 yr, from 1990 December to 2025 August. We have combined existing catalogs including magnetic obstacles (MOs) and identified and added boundaries of an additional 807 (40.8%) events. With this catalog, we demonstrate the most extensive analysis to date of total ICME magnetic field values as a function of heliocentric distance. Parker Solar Probe has observed six ICMEs at <0.23 au (until 2025 April), and Solar Orbiter and BepiColombo have added more events near 0.3 au, bridging the major observational gap towards the solar corona. Our main result is that a single power law can describe the evolution of the mean total magnetic field (exponent value of k = -1.57) and maximum field (k = -1.53) for ICMEs with MOs, from 0.07 to 5.4 au. Extending the power law to the solar photosphere reveals a strong inconsistency with magnetic field magnitudes observed in the quiet Sun and active regions by 2 and 4 orders of magnitude, respectively. We introduce a multipole-type power law with two exponents, k(1) = -1.57, and k(2) = -6, relating the ICME magnetic field magnitude to an average solar active region field strength. These results present important observational constraints for the evolution of ICMEs from the Sun to the heliosphere.

Real-world wireless transmitter frontends exhibit certain nonlinear behavior, e.g., signal clipping by a Power Amplifier (PA). Although many resource allocation solutions do not consider this for simplicity, it leads to inaccurate results or a reduced number of degrees of freedom, not achieving the global performance. In this work, we propose an optimal PA distortion-aware power allocation strategy in a downlink orthogonal frequency division multiplex (OFDM) based massive multiple-input multiple-output (M-MIMO) system. Assuming a soft-limiter PA model, where the transmission occurs under small-scale independent and identically distributed (i.i.d) Rayleigh fading channel, we derive the wideband signal-to-noise-and-distortion ratio (SNDR) and formulate the power allocation problem. Most interestingly, the distortion introduced by the PA leads to an SNDR-efficient operating point without explicit transmit power constraints. While the optimization problem is non-convex, we decouple it into a non-convex total power allocation problem and a convex power distribution problem among the users (UEs). We propose an alternating optimization algorithm to find the optimum solution. Our simulation results show significant sum-rate gains over existing distortion-neglecting solutions, e.g., a median 4 times increase and a median 50% increase for a 64-antenna and 512-antenna base station serving 60 users, respectively.

The blades of modern aero-engines are conceived for a specific design point. Due to the resulting fixed geometry of the blade, maximum engine efficiency can be achieved only for design point conditions. In order to improve the efficiency during off-design operation, applying blades with active shape control can be beneficial. Therefore, morphing fan blades, which adapt their geometry to the prevailing conditions by using piezoelectric low-profile actuators, are researched. Prior to the construction of a morphing fan blade demonstrator, a sequential multidisciplinary analysis is required to assess the feasibility of piezoelectric actuation in fan blades of future aircraft. First, the aerodynamic geometry of the fan blade is designed with respect to maximising the deformability. Subsequently, the structure of the morphing blade is developed, including a drapability analysis of the actuators and a numerical simulation of the achievable morphing deformation. Finally, the developed morphing structure is employed to examine a sufficient electrical power supply system for the morphing technology in a future electrified aircraft.

Review shows how electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) enables multifaceted studies of organic mixed ionic–electronic conductors (OMIECs), supporting organic electrochemical transistor (OECT) development.

Absolute line strengths of 28SiH4 were measured for the first time with a Bruker Fourier transform infrared spectrometer IFS120HR and analyzed in the 1180-1360 cm-1 region where the v1-v4, v3-v4, v3-v2 and v1-v2 "hot" bands of SiH4 are located. The strengths of 429 isolated nonsaturated and not too weak (i.e., which transmittances for the present experiment are no more than 97 per cent) spectral lines with the value of quantum number Jmax = 18, 14, 13, 13 for the bands v1-v4, v3-v2, v1-v2, and v3-v4 were obtained from the fit of their line shapes with a Voigt and Hartmann-Tran line profile and were used then in the weighted fit for determination of the effective dipole moment parameters of the studied "hot" bands. The obtained set of 5 fitted parameters reproduces the initial experimental line strengths with the drms = 5.7%. A list of the analyzed transitions with their line intensities is presents as the Supplementary data to this paper.