Learning the optimal power flow:Environment design matters

To solve the optimal power flow(OPF)problem,reinforcement learning(RL)emerges as a promising new approach.However,the RL-OPF literature is strongly divided regarding the exact formulation of the OPF problem as an RL environment.In this work,we collect and implement diverse environment design decisions from the literature regarding training data,observation space,episode definition,and reward function choice.In an experimental analysis,we show the significant impact of these environment design options on RL-OPF training performance.Further,we derive some first recommendations regarding the choice of these design decisions.The created environment framework is fully open-source and can serve as a benchmark for future research in the RL-OPF field.

Two-photon emission from a superlattice-based superconducting light-emitting structure

Superconductor-semiconductor hybrid devices can bridge the gap between solid-state-based and photonics-based quantum systems,enabling new hybrid computing schemes,offering increased scalability and robustness.One example for a hybrid device is the superconducting light-emitting diode(SLED).SLEDs have been theoretically shown to emit polarization-entangled photon pairs by utilizing radiative recombination of Cooper pairs.However,the twophoton nature of the emission has not been shown experimentally before.We demonstrate two-photon emission in a GaAs/AlGaAs SLED.Measured electroluminescence spectra reveal unique two-photon superconducting features below the critical temperature(Tc),while temperature-dependent photon-pair correlation experiments(g(2)(τ,T))demonstrate temperature-dependent time coincidences below Tc between photons emitted from the SLED.Our results pave the way for compact and efficient superconducting quantum light sources and open new directions in light-matter interaction studies.

The stability of carbon from a maize-derived hydrochar as a function of fractionation and hydrothermal carbonization temperature in a Podzol

Hydrochar(HC)produced by the hydrothermal carbonization(HTC)of typically wet biomass is generally considered to be less effective for carbon(C)sequestration in soils compared to biochar(BC)by pyrolysis,due to a higher content of more easily decomposable C.Although the recalcitrance of HC is suggested to improve with increasing HTC production temperature,the way it interacts and becomes associated with soil organic matter(SOM)fractions of different stabilities against decomposition,may also influence its effectiveness for C sequestration in soils.In that respect,this study aimed to verify the potential of HCs from maize silage produced at different HTC temperatures(190,210 and 230℃)for C sequestration in a HC-amended sandy loam Podzol.To do this,we conducted a pot trial experiment and traced the fate of HC-derived C(HC-C)within different SOM fractions,namely the free-and occluded particulate organic matter(POMF and POMO,respectively)fractions and that comprising organic matter(OM)bound to clays(OMCl).Approx.1 year after applying 5%of the different HTC temperature HCs to the soil,the SOM fractions were isolated by density fractionation for each HC treatment(HC190,HC210 and HC230)and the control(absent of HC).All fractions and the HCs were analyzed for organic C(OC)content and isotopic signatures(δ^(13)C).From the δ^(13)C signatures,the amount of HC-C and native soil organic carbon(SOC)within each fraction was calculated.Increased C contents and decreased H/C and O/C ratios were observed with increasing HTC production temperatures,which sug-gests a lower stability for the low temperature HC.After ca.1 year,a loss of~20-23%of the bulk soil TOC was found in the HC-amended soils.The POMF fraction of the HC-amended soils showed losses of 68-81%HC-C and 52-72%native SOC,which may be due to a positive priming effect caused by HC addition.The POM_(O) and OM_(Cl) fractions of the HC-amended soils contained more OC than the control,indicating the integration of HC-C together with SOM within these more stable fractions,while the effect of HTC production temperature on the level of decomposition of the resultant HCs was negligible.In all HC treatments,the OM_(Cl) fraction comprised the least amount of HC-C,thus showing the weakest response to C amendment.In conclusion,long(er)-term research on the C net balance that accounts for the observed priming-induced TOC losses and the HC-C enrichment in more stable fractions is required to verify the potential of the different HCs for the purpose of C sequestration in soils.

Revealing true coupling strengths in two-dimensional spectroscopy with sparsity-based signal recovery

Two-dimensional(2D)spectroscopy is used to study the interactions between energy levels in both the field of optics and nuclear magnetic resonance(NMR).Conventionally,the strength of interaction between two levels is inferred from the value of their common off-diagonal peak in the 2D spectrum,which is termed the cross peak.However,stronger diagonal peaks often have long tails that extend into the locations of the cross peaks and alter their values.Here,we introduce a method for retrieving the true interaction strengths by using sparse signal recovery techniques and apply our method in 2D Raman spectroscopy experiments.

Electronic fingerprint mechanism of NO_(x) sensor based on single-material SnP_(3) logical junction

An extraordinary sensing ability of the SnP3-based single-material logical junction for harmful NO_(x)gases was explored in the present work through a set of first-principles electronic structure calculations.As a sensing platform,a metal-semiconductor-metal lateral junction composed of a single material was designed based on the metallic/semiconducting characteristics of trilayer/monolayer SnP_(3).Lacking a Schottky barrier at the electrode-channel interface,the gas-specific charge transfer between the SnP_(3) layer and gas molecules was precisely detected based on the current-voltage characteristics.NO_(x)gases with strong adsorption strength and charge transfer amount on the SnP_(3)substrate were shown to be particularly well detected in this manner,in terms of either the absolute magnitude of the current or negative differential resistance(NDR)at a reasonably small bias voltage as a sensing signal.This work will provide a new pathway to design a Schottky barrier-free metal-semiconductor junction for highly sensitive sensor applications.