Bjorken xx weighted Energy-Energy Correlators from the Target Fragmentation Region to the Current Fragmentation Region

We present the complete spectrum for the Bjorken $x$ weighted Energy-Energy Correlation in the deep inelastic scattering (DIS) process, from the target fragmentation region to the current fragmentation region, in the Breit frame. The corresponding collinear and transverse momentum-dependent logarithms are resummed to all orders with the accuracy of NLL and N$^3$LL, respectively. And the results in the full region are matched with ${\cal O}(\alpha^2_s)$ fixed-order calculation. The final numerical predictions are presented for both EIC and CEBAF kinematics.Comment: 14 pages, 8 figure

Positive impact of a tower inlet cover on natural draft dry cooling towers under crosswind conditions

This study proposes a tower inlet cover to improve the performance of the small natural draft dry cooling tower (NDDCT) under crosswind conditions. CFD analyses are performed on a small NDDCT with tower inlet covers of different lengths, and the CFD model is validated against experimental results. The air temperature, air pressure, air flow and heat flux fields are presented, and the thermal performance for each heat exchanger and the NDDCT are obtained using CFD simulations. The CFD simulation results show that the high-pressure zone around the tower side wall, formed by the crosswind, causes the decrease in air flow through the tower and the deterioration in tower performance with a crosswind. The tower inlet cover can improve the tower performance in crosswinds by increasing the air flow of the heat exchangers. Tower inlet covers with lengths of 1.5 m, 3 m and 4.5 m improve the tower heat load by 40–65%, 70–130% and 85–230%, respectively, when the crosswind increases from 4 m/s to 12 m/s

Controlling Defect Formation of Nanoscale AlN: Toward Efficient Current Conduction of Ultrawide‐Bandgap Semiconductors

Ultrawide‐bandgap semiconductors such as AlN, BN, and diamond hold tremendous promise for high‐efficiency deep‐ultraviolet optoelectronics and high‐power/frequency electronics, but their practical application has been limited by poor current conduction. Through a combined theoretical and experimental study, it is shown that a critical challenge can be addressed for AlN nanostructures by using N‐rich epitaxy. Under N‐rich conditions, the p‐type Al‐substitutional Mg‐dopant formation energy is significantly reduced by 2 eV, whereas the formation energy for N‐vacancy related compensating defects is increased by ≈3 eV, both of which are essential to achieve high hole concentrations of AlN. Detailed analysis of the current−voltage characteristics of AlN p‐i‐n diodes suggests that current conduction is dominated by hole‐carrier tunneling at room temperature, which is directly related to the activation energy of Mg dopants. At high Mg concentrations, the dispersion of Mg acceptor energy levels leads to drastically reduced activation energy for a portion of Mg dopants, evidenced by the small tunneling energy of 67 meV, which explains the efficient current conduction and the very small turn‐on voltage (≈5 V) for the diodes made of nanoscale AlN. This work shows that nanostructures can overcome the dopability challenges of ultrawide‐bandgap semiconductors and significantly increase the efficiency of devices.Controlled defects formation and efficient current conduction of nanoscale AlN are realized. Under N‐rich epitaxy conditions, the formation energy for N‐vacancy related compensating defects is increased by nearly 3 eV, eliminating donor‐like compensating defects. Meanwhile, the p‐type Al‐substitutional Mg‐dopant formation energy is reduced by 2 eV, significantly enhancing Mg‐dopant incorporation and reducing hole carrier tunneling barrier.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162750/3/aelm202000337-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162750/2/aelm202000337_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162750/1/aelm202000337.pd

Interfacial Dipoles Boost Open-Circuit Voltage of Tin Halide Perovskite Solar Cells

Tin halide perovskites are promising materials for real-world photovoltaic applications, and there is large room for their performance to grow. We improved energy-level alignment between the perovskite and electron transport layers by introducing 4-fluorophen­ethylamine hydrobromide as an interfacial dipole. Thus, the open-circuit voltage of FASnI3 solar cells increased to 0.974 V and their power conversion efficiency reached 15.7%, representing a significant advance in this field

Interfacial Dipoles Boost Open-Circuit Voltage of Tin Halide Perovskite Solar Cells

Tin halide perovskites are promising materials for real-world photovoltaic applications, and there is large room for their performance to grow. We improved energy-level alignment between the perovskite and electron transport layers by introducing 4-fluorophen­ethylamine hydrobromide as an interfacial dipole. Thus, the open-circuit voltage of FASnI3 solar cells increased to 0.974 V and their power conversion efficiency reached 15.7%, representing a significant advance in this field