Lead sulfide quantum dots(PbS QDs) hold unique characteristics, including bandgap tunability, solutionprocessability etc., which make them highly applicable in tandem solar cells(TSCs). In all QD TSCs, its efficiency ...
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Lead sulfide quantum dots(PbS QDs) hold unique characteristics, including bandgap tunability, solutionprocessability etc., which make them highly applicable in tandem solar cells(TSCs). In all QD TSCs, its efficiency lags much behind to their single junction counterparts due to the deficient interconnection layer(ICL) and defective subcells. To improve TSCs performance, we developed three kinds of ICL structures based on 1.34 and 0.96 e V PbS QDs subcells. The control, 1,2-ethanedithiol capped PbS QDs(PbS-EDT)/Au/tin dioxide(SnO_(2))/zinc oxide(Zn O), utilized SnO_(2) layer to obtain high surface ***, its energy level mismatch causes incomplete recombination. Bypassing it, the second ICL(PbS-EDT/Au/Zn O) removed SnO_(2) and boosted the power conversion efficiency(PCE) from 5.75% to 8.69%. In the third ICL(PbS-EDT/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA)/Au/Zn O), a thin layer of PTAA can effectively fill fissures on the surface of PbS-EDT and also protect the front cells from solvent penetration. This TSC obtained a PCE of 9.49% with an open circuit voltage of 0.91 V, a short circuit current density of 15.47 m A/cm~2, and a fill factor of 67.7%. To the best of our knowledge, this was the highest PCE achieved by all PbS QD TSCs reported to date. These TSCs maintained stable performance for a long working time under ambient conditions.
An M6.8 earthquake occurred in Luding,Sichuan Province,China,on September 5,*** towns and villages in the earthquake-stricken area are densely populated,the earthquake caused severe fatalities and economic *** estimat...
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An M6.8 earthquake occurred in Luding,Sichuan Province,China,on September 5,*** towns and villages in the earthquake-stricken area are densely populated,the earthquake caused severe fatalities and economic *** estimation of earthquake intensity and disaster losses is significantly important for post-earthquake emergency rescue,scientific anti-seismic deployment,and the reduction of casualties and economic ***,we make a preliminary rapid estimation of the earthquake intensity and disaster losses in the aftermath of the Luding *** seismic intensity represents the distribution of earthquake disasters and the degree of ground damage and can be directly converted from the peak ground velocity(PGV)*** obtain a reliable PGV distribution map of this earthquake,we combined the finite-fault model constrained by seismic observations,with the complex three-dimensional(3D)geological environment and topographical features to perform strong ground motion ***,we compared the consistency between the simulated ground motion waveforms and observations,indicating the plausibility and reliability of *** addition,we transformed the PGV simulation results into intensity and obtained a physics-based map of the intensity distribution of the Luding *** maximum simulated intensity of this earthquake is IX,which is consistent with the maximum intensity determined from the postearthquake field *** on the simulated seismic intensity map of the Luding earthquake and the earthquake disaster loss estimation model,we rapidly estimated the death and economic losses caused by this *** estimated results show that the death toll caused by this earthquake is probably 50-300,with a mathematic expectation of *** the government should launch a Level II earthquake emergency response *** economic losses are likely to be 10-100 billion RMB,with a mathematical expectation of 23.205 billion *** seismic
Recently,the Fog-Radio Access Network(F-RAN)has gained considerable attention,because of its flexible architecture that allows rapid response to user *** this paper,computational offloading in F-RAN is considered,wher...
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Recently,the Fog-Radio Access Network(F-RAN)has gained considerable attention,because of its flexible architecture that allows rapid response to user *** this paper,computational offloading in F-RAN is considered,where multiple User Equipments(UEs)offload their computational tasks to the F-RAN through fog *** UE can select one of the fog nodes to offload its task,and each fog node may serve multiple *** tasks are computed by the fog nodes or further offloaded to the cloud via a capacity-limited fronhaul *** order to compute all UEs'tasks quickly,joint optimization of UE-Fog association,radio and computation resources of F-RAN is proposed to minimize the maximum latency of all *** min-max problem is formulated as a Mixed Integer Nonlinear program(MINP).To tackle it,first,MINP is reformulated as a continuous optimization problem,and then the Majorization Minimization(MM)method is used to find a *** MM approach that we develop is unconventional in that each MM subproblem is solved inexactly with the same provable convergence guarantee as the exact MM,thereby reducing the complexity of MM *** addition,a cooperative offloading model is considered,where the fog nodes compress-and-forward their received signals to the *** this model,a similar min-max latency optimization problem is formulated and tackled by the inexact *** results show that the proposed algorithms outperform some offloading strategies,and that the cooperative offloading can exploit transmission diversity better than noncooperative offloading to achieve better latency performance.
We here report a probable detection of a stellar coronal mass ejection(CME)in active M dwarf KIC 8093473 by performing an analysis on its time resolved X-ray spectra observed by the XMM-Newton *** to the value at the ...
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We here report a probable detection of a stellar coronal mass ejection(CME)in active M dwarf KIC 8093473 by performing an analysis on its time resolved X-ray spectra observed by the XMM-Newton *** to the value at the quiescent state and the interstellar one,our spectral modeling returns a marginal(and probably evolving)excess of hydrogen column density in the flare state at a significance level of 1σ,which can be understood by an additional absorption due to a flare-associate *** CME mass is then estimated to be∼7×10^(18)–2×10^(20)g according to the ice cream cone model.
In the fields of weapon platform stealth design and radar target recognition, there is an urgent need for precise electromagnetic scattering analysis of complex, largescale objects (» 1000 wavelengths). Although ...
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Microwave coincidence imaging (MCI) is a novel imaging technique, which has high-resolution potential in forward-looking imaging. Most of the existing microwave coincidence imaging methods utilize random frequency mod...
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Standard collisionless magnetic reconnection couples with both electron and ion dynamics. Recently, a new type of magnetic reconnection, electron-only magnetic reconnection without ion outflow, has been observed. Usin...
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Standard collisionless magnetic reconnection couples with both electron and ion dynamics. Recently, a new type of magnetic reconnection, electron-only magnetic reconnection without ion outflow, has been observed. Using 2.5D particle-in-cell simulation, the electromagnetic field structure in the electron-only reconnection with a strong guide field was studied. At the moment of the maximum reconnection rate, the electron inflow and outflow are observed on either side of the separatrix. The spatial distribution of the electron bulk velocity is approximately symmetric, which generates the nearly symmetrically distributed Hall current, resulting in the quadrupole Hall magnetic field. The Hall magnetic field is not obviously distorted despite the presence of the strong guide field. Meanwhile, the charge separation is caused in the separatrix region, which generates the nearly symmetrically distributed Hall electric field. Besides, the evolution of the spatial distribution of the electron bulk velocity was studied. The equation of motion for the frozen electrons was analytically obtained: ve=veyB/By+E×(Byey)/By2. According to the equation of motion for the electrons, we divide the electron-only reconnection with a strong guide field into two stages. In the first stage, the E×B drift is negligible because of the weaker Hall electric field, and then the electrons flow mainly along the magnetic field line following the equation ve≈veyB/By. In the second stage, the Hall electric field is so strong that the motion of electrons is dominated by the E×B drift following the equation ve≈E×(Byey)/By2. The simulation shows that extremely strong charge separation can be caused in electron-only reconnection, which generates the nearly symmetrically distributed Hall electric field. With a guide field, this Hall electric field
Both safety and stability are primary performance criteria for multi-unmanned aerial vehicle(multi-UAV)systems in many coordination *** approaches often consider safety and stability *** is necessary and urgent to dev...
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Both safety and stability are primary performance criteria for multi-unmanned aerial vehicle(multi-UAV)systems in many coordination *** approaches often consider safety and stability *** is necessary and urgent to develop a safety-stability control strategy to merge these two performance *** this paper,a unified approach is developed to consider safety and stability for multi-UAV formation *** stability criterion is represented by a Lyapunov function and safety criterion is represented by a barrier function and then a relaxed converse control Lyapunov-barrier theorem is *** the help of a relaxed converse control Lyapunov-barrier function(RCCLBF),a distributed safety-stability formation control strategy is proposed for the multi-UAV *** transforming the solution of RCCLBF to a Lyapunovlike stabilization problem,we show that the proposed formation control strategy can drive the UAVs staying within a specified safe *** results are provided to validate the proposed safety-stability formation control strategy.
This research aims to create a virtual reality-based practice system that simulates real-stage performance environments, assisting amateur dancers in overcoming stage fright and practicing group choreography that is d...
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Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in *** hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indi...
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Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in *** hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indirect imaging technique that requires algorithms to reconstruct and optimize *** the last decade,a variety of algorithms have been developed and ***,it is difficult to quantitatively evaluate the image quality of different solutions without a true,reference image of *** to choose the values of imaging parameters for these algorithms to get the best performance is also an open *** this study,we present a detailed test of the characteristics of these algorithms,imaging dynamic range and a crucial parameter for the CLEAN method,clean beam width factor(CBWF).We first used SDO/AIA EUV images to compute DEM maps and calculate thermal X-ray *** these realistic sources and several types of simulated sources are used as the ground truth in the imaging simulations for both RHESSI and ASO-S/*** different solutions are evaluated quantitatively by a number of *** overall results suggest that EM,PIXON,and CLEAN are exceptional methods for sidelobe elimination,producing images with clear source *** MEM_GE,MEM_NJIT,VIS_WV and VIS_CS possess fast imaging processes and generate good images,they too possess associated imperfections unique to each *** two forward fit algorithms,VF and FF,perform differently,and VF appears to be more robust and *** also demonstrated the imaging capability of HXI and available HXI ***,the effect of CBWF on image quality was investigated,and the optimal settings for both RHESSI and HXI were proposed.
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