Lockdown spillovers.

Lockdowns imposed to fight the Covid-19 pandemic have cross-border effects. In this paper, we estimate the empirical magnitude of lockdown spillovers in a set of panel local projections. We use daily indicators of economic activity such as stock returns, effective exchange rates, NO2 emissions, mobility and maritime container trade. Lockdown shocks originating in the most important trading partners have a strong and significant adverse effect on economic activity in the home economy. For stock prices and exports, the spillovers can even be larger than the effect of domestic lockdown shocks. The results are robust with respect to alternative country weights used to construct foreign shocks, i.e. weights based on foreign direct investment or the connectedness through value chains. We find that lockdown spillovers have been particularly strong during the first wave of the pandemic. Countries with a higher export share are particularly exposed to lockdown spillovers.

Optimizing metal grating back reflectors for III-V-on-silicon multijunction solar cells.

Multi-junction solar cells allow to utilize sunlight more effectively than single junction solar cells. In this work, we present optical simulations of III-V-on-silicon solar cells with a metal grating at the back, which experimentally have reached more than 33% power conversion efficiency. First, we perform simulations with the finite element method and compare them with experimental data to validate our model. We find that accurately modeling the investigated geometrical structure is necessary for best agreement between simulation and experimental measurements. Then, we optimize the grating for maximized light trapping using a computationally efficient Bayesian optimization algorithm. The photo current density of the limiting silicon bottom cell is improved from 13.48 mA/cm2 for the experimental grating to 13.85 mA/cm2 for the optimized metal grating. Investigation of all geometrical optimization parameters of the grating (period, height,…) shows that the structure is most sensitive towards the period, a parameter highly controllable in manufacturing by inference lithography. The results show a pathway to exceed the current world record efficiency of the III-V-on-silicon solar cell technology.

Detailed illumination model for bifacial solar cells.

We present a detailed illumination model for bifacial photovoltaic modules in a large PV field. The model considers direct light and diffuse light from the sky and treats the illumination of the ground in detail, where it discriminates between illumination of the ground arising from diffuse and direct light. The model calculates the irradiance components on arbitrarily many positions along the module. This is relevant for finding the minimal irradiance, which determines the PV module performance for many PV modules. Finally, we discuss several examples. The code for the model is available online (DOI: 10.5281/zenodo.3543570).

A new near-infrared reflectance spectroscopy method for high-throughput analysis of oleic acid and linolenic acid content of single seeds in oilseed rape (Brassica napus L.).

The development of oilseed rape cultivars with a high content of oleic acid (18:1) and a low content of linolenic acid (18:3) in the seed oil is an important breeding aim. Oil of this quality is increasingly being sought by the food and the oleochemical industry. Since the oil quality is determined by the genotype of the seed, a selection can be performed among single seeds of segregating populations. For this purpose a high-throughput Near-Infrared Reflectance Spectroscopy (NIRS) method using an automated sample presentation unit for single seeds of oilseed rape and a spectrometer equipped with a photodiode array detector was developed. Single-seed analyses have been accomplished with a throughput of up to 800 seeds per hour. Seeds from segregating populations of different origin were analyzed by NIRS and gas chromatography. Calibration equations were developed and validated applying the Modified Partial Least Square regression (MPLS) and LOCAL procedure. In three independent validations, standard errors of prediction corrected for bias between 2.7% and 3.7% for oleic acid and 1.2% and 1.8% for linolenic acid were determined using MPLS. Similar results were obtained applying the LOCAL procedure. The results show that the new high-throughput method can be applied to predict the oleic acid and linolenic acid content of single seeds of oilseed rape.