Influence of donor:acceptor ratio on charge transfer dynamics in non-fullerene organic bulk heterojunctions

The donor:acceptor(D:A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction(BHJ) orga nic solar cells(OSCs).The proper D:A blend ratio can provide maximized D/A interfacial area for exciton dissociation and appro p riate domain size of the exciton diffusion length,which is beneficial to obtain high-performance OSCs.Here,we comprehensively investigated the relationship between various D:A blend ratios and the charge transfer and energy transfer mechanisms in OSCs based on PBDB-T and non-fullerene acceptor IT-M.Based on various D:A blend ratios,it was found that the ratio of components is a key factor to suppress the formation of triplet states and recombination energy losses.Rational D:A blend ratios can provide appropriate donor/accepter surface for charge transfer which has been powerfully verified by various detailed experimental results from the time-resolved fluorescence measurement and transient absorption(TA) spectroscopy.Optimized coherence length and crystallinity are verified by grazing incident wide-angle X-ray scattering(GIWAXS) measurements.The results are bene ficial to comprehend the effects of various D:A blend ratios on charge transfer and energy transfer dynamics and provides constructive suggestions for rationally designing new materials and feedback for photovoltaic performance optimization in non-fullerene OSCs.

Numerical Study of Fluid Dynamics and Heat Transfer Induced by Plasma Discharges

A numerical investigation is conducted to explore the evolution of a plasma discharge and its interaction with the fluid flow based on a self-consistent fluid model which couples the discharge dynamics with the fluid dynamics.The effects of the applied voltage on the distribution of velocity and temperature in initially static air are parainetrically studied.Furthermore,the spatial structure of plasma discharge and the resulting force contours in streamwise and normal directions are discussed in detail.The result shows that the plasma actuator produces a net force that should always be directed away from the exposed electrode,which results in an ionic wind pushing particles into a jet downstream of the actuator.When the energy added by the plasma is taken into account,the ambient air temperature is increased slightly around the electrode,but the velocity is almost not affected.Therefore it is unlikely that the induced flow is buoyancy driven.For the operating voltages considered in this paper,the maximum induced velocity is found to follow a power law,i.e.,it is proportional to the applied voltage to the 3.5 power.This promises an efficient application in the flow control with plasma actuators.

Motion-Enhanced Quantum Entanglement in the Dynamics of Excitation Transfer

We investigate the dynamics of entanglement in the excitation transfer through a model consisting of three interacting molecules coupled to environments. It is shown that the entanglement can be further enhanced if the distance between the molecules is oscillating. Our results demonstrate that the motional effect plays a constructive role on quantum entanglement in the dynamics of excitation transfer. This mechanism might provide a useful guideline for designing artificial systems to battle against decoherence.

Designing an Effective Method for Automatic Electric Vehicle Charging Stations in a Static Environment

This article outlines an Effective Method for Automatic Electric Vehicle Charging Stations in a Static Environment. It consists of investigated wireless transformer structures with various ferrite forms. WPT technology has rapidly advanced in the last few years. At kilowatt power levels, the transmission distance grows from a few millimeters to several hundred millimeters with a grid to load efficiency greater than 90%. The improvements have made the WPT more appealing for electric vehicle (EV) charging applications in both static and dynamic charging scenarios. Static and dynamic WEVCS, two of the main applications, are described, and current developments with features from research facilities, academic institutions, and businesses are noted. Additionally, forthcoming concepts based WEVCS are analyzed and examined, including “dynamic” wireless charging systems (WCS). A dynamic wireless power transfer (DWPT) system, which can supply electricity to moving EVs, is one of the feasible alternatives. The moving secondary coil is part of the dynamic WPT system, which also comprises of many fixed groundside (primary) coils. An equivalent circuit between the stationary system and the dynamic WPT system that results from the stationary system is demonstrated by theoretical investigations. The dynamic WPT system’s solenoid coils outperform circular coils in terms of flux distribution and misalignment. The WPT-related EV wireless charging technologies were examined in this study. WPT can assist EVs in overcoming their restrictions on cost, range, and charging time.

Vibration-assisted coherent excitation energy transfer in a detuned dimer

The important role of high-energy intramolecular vibrational modes for excitation energy transfer in the detuned photosynthetic systems is studied. Based on a basic dimer model which consists of two two-level systems （pigments） coupled to high-energy vibrational modes, we find that the high-energy intramolecular vibrational modes can enhance the energy transfer with new coherent transfer channels being opened when the phonon energy matches the detuning between the two pigments. As a result, the energy can be effectively transferred into the acceptor. The effective Hamiltonian is obtained to reveal the strong coherent energy exchange among the donor, the acceptor, and the high-energy intramolecular. A semi-classical explanation of the phonon-assisted mechanism is also shown.

A new algorithm of global tightly-coupled transient heat transfer based on quasi-steady flow to the conjugate heat transfer problem

Concerning the specific demand on solving the long-term conjugate heat transfer （CHT） problem, a new algorithm of the global tightly-coupled transient heat transfer based on the quasi-steady flow field is further put forward. Compared to the traditional loosely-coupled algorithm, the computational efficiency is further improved with the greatly reduced update frequency of the flow field, and moreover the update step of the flow field can be reasonably determined by using the engineering empirical formula of the Nusselt number based on the changes of the inlet and outlet boundary conditions. Taking a duct heated by inner forced air flow heating process as an example, the comparing results to the tightly-coupled transient calculation by Fluent software shows that the new algorithm can significantly improve the computational efficiency with a reasonable accuracy on the transient temperature distribution, such as the computing time is reduced to 22,8% and 40% while the duct wall temperature deviation are 7% and 5% respectively using two flow update time step of 100 s and 50 s on the variable inlet-flow rate conditions.

Dynamic Ensemble Multivariate Time Series Forecasting Model for PM2.5

In forecasting real time environmental factors,large data is needed to analyse the pattern behind the data values.Air pollution is a major threat towards developing countries and it is proliferating every year.Many methods in time ser-ies prediction and deep learning models to estimate the severity of air pollution.Each independent variable contributing towards pollution is necessary to analyse the trend behind the air pollution in that particular locality.This approach selects multivariate time series and coalesce a real time updatable autoregressive model to forecast Particulate matter(PM)PM2.5.To perform experimental analysis the data from the Central Pollution Control Board(CPCB)is used.Prediction is car-ried out for Chennai with seven locations and estimated PM’s using the weighted ensemble method.Proposed method for air pollution prediction unveiled effective and moored performance in long term prediction.Dynamic budge with high weighted k-models are used simultaneously and devising an ensemble helps to achieve stable forecasting.Computational time of ensemble decreases with paral-lel processing in each sub model.Weighted ensemble model shows high perfor-mance in long term prediction when compared to the traditional time series models like Vector Auto-Regression(VAR),Autoregressive Integrated with Mov-ing Average(ARIMA),Autoregressive Moving Average with Extended terms(ARMEX).Evaluation metrics like Root Mean Square Error(RMSE),Mean Absolute Error(MAE)and the time to achieve the time series are compared.

Regional Characteristics of Typhoon-Induced Ocean Eddies in the East China Sea

The asymmetrical structure of typhoon-induced ocean eddies（TIOEs） in the East China Sea（including the Yellow Sea）and the accompanying air–sea interaction are studied using reanalysis products. Thirteen TIOEs are analyzed and divided into three groups with the k-prototype method： Group A with typhoons passing through the central Yellow Sea; Group B with typhoons re-entering the sea from the western Yellow Sea after landing on continental China; and Group C with typhoons occurring across the eastern Yellow Sea near to the Korean Peninsula. The study region is divided into three zones（Zones Ⅰ, Ⅱ and Ⅲ） according to water depth and the Kuroshio position. The TIOEs in Group A are the strongest and could reverse part of the Kuroshio stream, while TIOEs in the other two groups are easily deformed by topography. The strong currents of the TIOEs impact on the latent heat flux distribution and upward transport, which facilitates the typhoon development. The strong divergence within the TIOEs favors an upwelling-induced cooling. A typical TIOE analysis shows that the intensity of the upwelling of TIOEs is proportional to the water depth, but its magnitude is weaker than the upwelling induced by the topography. In Zones Ⅰ and Ⅱ, the vertical dimensions of TIOEs and their strong currents are much less than the water depths.In shallow water Zone Ⅲ, a reversed circulation appears in the lower layer. The strong currents can lead to a greater, faster,and deeper energy transfer downwards than at the center of TIOEs.

WRIST FORCE SENSOR'S DYNAMIC PERFORMANCE CALIBRATION BASED ON NEGATIVE STEP RESPONSE

Negative step response experimental method is used in wrist force sensor＇s dynamic performance calibration. The exciting manner of negative step response method is the same as wrist force sensor＇s load in working. This experimental method needn＇t special experiment equipments. Experiment＇s dynamic repeatability is good. So wrist force sensor＇s dynamic performance is suitable to be calibrated by negative step response method. A new correlation wavelet transfer method is studied. By wavelet transfer method, the signal is decomposed into two dimensional spaces of time-frequency. So the problem of negative step exciting energy concentrating in the low frequency band is solved. Correlation wavelet transfer doesn＇t require that wavelet primary function be orthogonal and needn＇t wavelet reconstruction. So analyzing efficiency is high. An experimental bench is designed and manufactured to load the wrist force sensor orthogonal excitation force/moment. A piezoelectric force sensor is used to setup soft trigger and calculate the value of negative step excitation. A wrist force sensor is calibrated. The pulse response function is calculated after negative step excitation and step response have been transformed to positive step excitation and step response. The pulse response function is transferred to frequency response function. The wrist force sensor＇s dynamic characteristics are identified by the frequency response function.

DYNAMIC CHARACTERISTICS ON PRECISION NC LATHE BASED ON MULTI-BODY SYSTEM THEORY

Based on multi-body system theory and the mainshafl system of precision NC lathe as object investigated, it is treated as a coupled rigid-flexible multi-body system which is made up of some rigid and elastic bodies in an especial linking mode. And a dynamic model is established, The problems of computing vibration characteristics are resolved by using multi-body system transfer matrix method, Resutts show that the mainshaft system of NC lathe is in the stable and reliable working area all the time. The method is simple and easy, the idea is clear. In addition, the method can be easily used and popularized in the other multi-body system.

Solar Activity and Classical Physics

This review of solar physics emphasizes several of the more conspicuous scientific puzzles posed by contemporary observational knowledge of the magnetic activity of the Sun. The puzzles emphasize how much classical physics we have yet to learn from the Sun. The physics of solar activity is based on the principles of Newton, Maxwell, Lorentz, Boltzmann, et. al., along with the principles of radiative transfer. In the large, these principles are expressed by magnetohydro dynamics. A brief derivation of the magnetohydrodynamic induction and moment um equations is provided, with a discussion of popular misconceptions.

Dynamic transfer model and applications of a penetrating projectile‐fuze multibody system

In modern warfare,fortifications are being placed deeper underground and with increased mechanical strength,placing higher demands on the target speed of the penetrating munitions that attack them.In such practical scenarios,penetrating fuze inevitably experience extreme mechanical loads with long pulse durations and high shock strengths.Experimental results indicate that their shock accelerations can even exceed those of the projectile by several times.However,due to the unclear understanding of the dynamic transfer mechanism of the penetrating fuze system under such extreme mechanical conditions,there is still a lack of effective methods to accurately estimate and design protection against the impact loads on the penetrating fuze.This paper focuses on the dynamic response of penetrating munitions and fuzes under high impact,establishing a nonlinear dynamic transfer model for penetrating fuze systems,which can calculate the sensor overload signal of the fuze location.The results show that the relative error between the peak acceleration obtained by the proposed multibody dynamic transfer model and that obtained by experimental tests is only 15.7%,which is much lower than the 26.4%error between finite element simulations and experimental tests.The computational burden of the proposed method mainly lies in the parameter calibration process,which needs to be performed only once for a specific projectile‐fuze system.Once calibrated,the model can rapidly conduct parameter scanning simulations for the projectile mass,target plate strength,and impact velocity with an extremely low computational cost to obtain the response characteristics of the projectile‐fuze system under various operating conditions.This greatly facilitates the practical engineering design of penetrating ammunition fuze.

Promoted surface charge density from interlayer Zn–N_(4) configuration in carbon nitride for enhanced CO_(2) photoreduction

The solar-driven reduction of CO_(2) into valuable products is a promising method to alleviate global environmental problems and energy crises.However,the low surface charge density limits the photocatalytic conversion performance of CO_(2).Herein,a polymeric carbon nitride(PCN)photocatalyst with Zn single atoms(Zn1/CN)was designed and synthesized for CO_(2) photoreduction.The results of the CO_(2) photoreduction studies show that the CO and CH_(4) yields of Zn1/CN increased fivefold,reaching 76.9 and 22.9μmol/(g·h),respectively,in contrast to the unmodified PCN.Ar+plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn–N_(4) configuration.Photoelectrochemical characterizations indicate that the interlayer Zn–N_(4) configuration can amplify light absorption and establish an interlayer charge transfer channel.Light-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn–N_(4) configuration,which increases its surface charge density.Further,in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates(*COOH)conversion,thus achieving efficient CO_(2) conversion.This work elucidates the role of internal single atoms in catalytic surface reactions,which provides important implications for the design of single-atom catalysts.

Constructing Pd-N interactions in Pd/g-C_(3)N_(4)to improve the charge dynamics for efficient photocatalytic hydrogen evolution

The formation of chemical bonds between metal ions and their supports is an effective strategy to achieve good catalytic activity.However,both the synthesis of active metal species on a support and control of their coordination environment are still challenging.Here,we show the use of an organic compound to produce tubular carbon nitride(TCN)as a support for Pd nanoparticles(NPs),creating a composite material(NP-Pd-TCN).It was found that Pd ions preferentially bind with the electron-rich N atoms of TCN,leading to strong metal-support interactions that benefit charge transfer from g-C_(3)N_(4)to Pd.X-ray absorption spectroscopy further revealed that the metal-support interactions resulted in the formation of Pd-N bonds,which are responsible for the improvement in the charge dynamics as evidenced by the results from various techniques including photoluminescence(PL)spectroscopy,photocurrent measurements,and electrochemical impedance spectroscopy(EIS).Owing to the good dynamical properties,NP-Pd-TCN was used for photocatalytic hydrogen evolution under visible-light irradiation(λ>420 nm)and an excellent evolution rate of~381μmol·h^(-1)(0.02 g of the photocatalyst)was attained.This work aims to promote a strategy to synthesize efficient photocatalysts for hydrogen production by controllably introducing metal nanoparticles on a support and in the meantime forming chemical bonds to achieve intimate metal-support contact.

Secondary solar heat gain modelling of spectral-selective glazing based on dynamic solar radiation spectrum

The secondary solar heat gain,defined as the heat flows from glazing to indoor environment through longwave radiation and convection,grows with the increasing of glazing absorption.With the rapid development and application of spectrally selective glazing,the secondary solar heat gain becomes the main way of glazing heat transfer and biggest proportion,and indicates it should not be simplified calculated conventionally.Therefore,a dynamic secondary solar heat gain model is developed with electrochromic glazing system in this study,taking into account with three key aspects,namely,optical model,heat transfer model,and outdoor radiation spectrum.Compared with the traditional K-Sc model,this new model is verified by on-site experimental measurements with dynamic outdoor spectrum and temperature.The verification results show that the root mean square errors of the interior and exterior glass surface temperature are 3.25°C and 3.33°C,respectively,and the relative error is less than 10.37%.The root mean square error of the secondary heat gain is 13.15 W/m2,and the dynamic maximum relative error is only 13.2%.The simulated and measured results have a good agreement.In addition,the new model is further extended to reveal the variation characteristics of secondary solar heat gain under different application conditions(including orientations,locations,EC film thicknesses and weather conditions).In summary,based on the outdoor spectrum and window spectral characteristics,the new model can accurately calculate the increasing secondary solar heat gain in real time,caused by spectrally selective windows,and will provide a computational basis for the evaluation and development of spectrally selective glazing materials.

高效制备优质Cs2AgBiBr6薄膜及其太阳能电池

无铅双钙钛矿Cs2AgBiBr6与铅基钙钛矿相比具有更高的稳定性和更低的毒性,被认为是很有前途的下一代光伏材料.在实际应用中,人们迫切需要一种简便的沉积方法来制备高质量、大晶粒尺寸的双钙钛矿薄膜.然而,目前尚未找到制备Cs2AgBiBr6薄膜的简便方法.本文通过简单的一步旋涂法成功制备了晶粒尺寸达0.5μm的高质量Cs2AgBiBr6薄膜,该方法使用体积比优化后的二甲基亚砜-二甲基甲酰胺(DMSO-DMF)混合溶液作为溶剂,氯苯作为反溶剂.基于良好的薄膜质量,制备了高效(>1%)Cs2AgBiBr6钙钛矿太阳能电池.此外,利用飞秒瞬态光谱系统地研究了Cs2AgBiBr6与相邻的载流子传输层之间的光生电荷转移.本工作为制备高质量的Cs2AgBiBr6薄膜开辟了新方法,为高效双钙钛矿太阳能电池的发展提供了有益指导.

Dynamic transfer and driving mechanisms of the coupling and coordination of agricultural resilience and rural land use efficiency in China

The joint study of agriculture and rural areas is of great significance for safeguarding agricultural development,revitalizing rural areas,and enhancing farmers'well-being.This paper aims to assess the spatiotemporal evolution characteristics of the coupling and coordination degree of agricultural resilience and rural land use efficiency and their dynamic transfer law and driving mechanisms,based on panel data of 31 provinces(municipalities and autonomous regions)in China from 2010 to 2020.The results showed:(1)Good coupling and coordination of agricultural resilience and rural land use efficiency,with reduced temporal differentiation degrees between regions;(2)Significant spatial autocorrelation between the overall coupling and coordination degrees of agricultural resilience and rural land use efficiency,forming cold spot and hot spot spatial patterns in the western and eastern parts,respectively,with a central transition area;(3)A spillover effect of the dynamic transfer process,with a manifested specific law as"club convergence","Matthew effect",and progressive development characteristics;(4)The key roles of the natural,social,economic,and policy indicators in the coupling and coordination development process of agricultural resilience and rural land use efficiency.However,the selected indicators showed substantial spatial differences in their influences on the coupling and coordination process between provinces.

Synthesis and photoluminescent performance of novel europium(Ⅲ) carboxylates with heterocyclic ancillary ligands

Five novel europium(Ⅲ)complexes with 2-[4-(dibutylamino)-2-hydroxybenzoyl]benzoic acid(DAHB)as primary ligand and bathophenanthroline(batho),2,2’-bipyridyl(bipy),5,6-dimethyl-1,10-phenanthroline(dmph),1,10-phenanthroline(phen)as ancillary ligands were syn-thesized via solution precipitation method.The structural formulae of synthesized complexes were speculated to be Eu(DABH)_(3)·2H_(2)O(C1),Eu(DABH)_(3)·batho(C2),Eu(DABH)_(3)·bipy(C3),Eu(DABH)_(3)·dmph(C4)and Eu(DABH)_(3)·phen(C5)by elemental analysis,infrared spectroscopy and proton nuclear magnetic resonance spec-troscopy(^(1)H-NMR).The photoluminescent properties and thermal stability of the complexes were investigated by photoluminescent spectroscopy and thermogravimetric analysis(TG-DTG),respectively.The Commission Inter-nationale de I’Eclairage(CIE)color coordinates,Judd–Ofelt intensity parameter(Ω_(2)),total quantum yield,intrinsic quantum efficiency and energy transfer dynamics of com-plexes were also explored.The excitation spectra of com-plexes are extended up to visible region.These complexes exhibit characteristic photoemission of Eu^(3+)metal ion with high color purity in red region attributed to efficient energy transfer from ligand to metal ion.The replacement of water molecules from coordination sphere of europium ion by ancillary ligands results in enhancement of luminescent properties of the C2–C5 complexes,indicating that ancillary ligands act as additional light harvesting centers in sensiti-zation phenomenon.The thermal studies show that these complexes are suitable for meeting the requirement of temperature for fabrication of OLEDs devices.

Ultrafast solid-liquid-vapor irradiated by femtosecond phase change of a thin gold fi laser pulses and pulse trains

Effects of different parameters on the melting, vaporization and resolidification processes of thin gold film irradiated by femtosecond pulses and pulse train were systematically studied. The classical two-temperature model was adopted to depict the non-equilibrium heat transfer in electrons and lattice, the melting and resolidification processes, which was~ characterized by the solid-liquid interfacial velocity, as well as elevated melting temperature and depressed solidifcation tempera- ture, was obtained by considering the interfacial energy balance and nucleation dynamics. Vaporization process which leads to ablation was described by tracking the location of liquid-vapor interface with an iterative procedure based on energy balance and gas kinetics law. The parameters in discussion included film thickness, laser fluence, pulse duration, pulse number, repetition rate, pulse train number, etc. Their effects on the maximum lattice temperature, melting depth and ablation depth were discussed based on the simulation results.