Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(...Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional(2D)(BA)_(2)(MA)_(n-1)Pbn I_(3n+1)(n = 1, 2, 3, 4, 5)(where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells(PSCs) to construct a fourterminal(4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell(n = 4) obtains a power conversion efficiency(PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride(LiF) anti-reflection layer to reduce the surface reflection loss, the current density(J_(sc)) of the top cell is enhanced from 15.56 m A/cm^(2) to 17.09 m A/cm^(2), the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions.展开更多
In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditio...In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors,reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption.Owing to the ultrathin structure,effective control of the electronic characteristics and ability to modulate structural defects,two-dimensional(2D)materials have been widely used to fabricate reconfigurable devices.In this review,we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials,including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations.Furthermore,we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors,respectively,therefore highlighting the outstanding advantages of reconfigurable devices in footprint,energy consumption and performance.Finally,we discuss the challenges of the 2D materials-based reconfigurable devices.展开更多
To explore the feasibility of electrospray-based additive manufacturing for thin-film fabrication in zero-or microgravity environments,we conducted numerical simulations of charged droplet behavior under zero-gravity ...To explore the feasibility of electrospray-based additive manufacturing for thin-film fabrication in zero-or microgravity environments,we conducted numerical simulations of charged droplet behavior under zero-gravity conditions,followed by ground-based experimental validation using an anti-gravity electrospray(AG-ES)strategy.First,simulations of charged droplet deposition during the electrospray process showed that the presence or absence of gravity did not significantly affect deposition behavior.Second,simulations of droplet-substrate collisions indicated that the presence of an electric field could reduce the risk of droplet splashing.Third,simulations of droplet coalescence under zero-gravity conditions demonstrated that an electric field could promote the coalescence of charged droplets.An AG-ES experimental platform featuring an inverted nozzle-substrate configuration was constructed on the ground.Comparative experiments using Rhodamine B solution and TiO_(2)nanoparticle dispersions were performed in both AG-ES and conventional electrospray(ES)modes.The results indicated that the spray cone angle,deposition area,and film morphology were comparable between the two modes.Finally,multilayer alternating-current electroluminescent(ACEL)devices were fabricated via AG-ES using ZnS:Cu/poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP),BaTiO_(3)/polyvinylpyrrolidone(PVP),and silver nanowire(AgNW)inks,achieving a maximum luminance of 66.2 cd/m^(2).This study demonstrates the potential of the electrospray process for functional thin-film fabrication under microgravity conditions.展开更多
Solar Design(https://solardesign.cn/)is an online photovoltaic device simulation and design platform that provides engineering modeling analysis for crystalline silicon solar cells,as well as emerging high-efficiency ...Solar Design(https://solardesign.cn/)is an online photovoltaic device simulation and design platform that provides engineering modeling analysis for crystalline silicon solar cells,as well as emerging high-efficiency solar cells such as organic,perovskite,and tandem cells.The platform offers user-updatable libraries of basic photovoltaic materials and devices,device-level multi-physics simulations involving optical–electrical–thermal interactions,and circuit-level compact model simulations based on detailed balance theory.Employing internationally advanced numerical methods,the platform accurately,rapidly,and efficiently solves optical absorption,electrical transport,and compact circuit models.It achieves multi-level photovoltaic simulation technology from“materials to devices to circuits”with fully independent intellectual property rights.Compared to commercial softwares,the platform achieves high accuracy and improves speed by more than an order of magnitude.Additionally,it can simulate unique electrical transport processes in emerging solar cells,such as quantum tunneling,exciton dissociation,and ion migration.展开更多
The performance and efficiency of hydraulic excavators heavily depend on the design and optimization of their working devices.The working device,which consists of the boom,arm,and bucket,plays a crucial role in determ...The performance and efficiency of hydraulic excavators heavily depend on the design and optimization of their working devices.The working device,which consists of the boom,arm,and bucket,plays a crucial role in determining the machine's digging capacity,stability,and overall operational efficiency.This paper presents a comprehensive study on the dynamics simulation and optimization of hydraulic excavator working devices.The paper outlines the fundamental principles of dynamic modeling,incorporating multi-body dynamics and hydraulic system analysis.It further explores various simulation techniques to evaluate the performance of the working device under varying operational conditions,including load and hydraulic system effects.The study also addresses performance optimization,focusing on multi-objective optimization methods that balance multiple factors such as energy efficiency,speed,and load capacity.Additionally,the paper discusses key factors influencing performance,such as mechanical design,material properties,and operational conditions.The results of the dynamic simulations and optimization analyses demonstrate potential improvements in operational efficiency and system stability,providing a valuable framework for the design and enhancement of hydraulic excavator working devices.展开更多
Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by usin...Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.展开更多
The lead-free perovskite solar cells(PSCs) have drawn a great deal of research interest due to the Pb toxicity of the lead halide perovskite.CHNHSnIis a viable alternative to CHNHPbX,because it has a narrower band gap...The lead-free perovskite solar cells(PSCs) have drawn a great deal of research interest due to the Pb toxicity of the lead halide perovskite.CHNHSnIis a viable alternative to CHNHPbX,because it has a narrower band gap of 1.3 eV and a wider visible absorption spectrum than the lead halide perovskite.The progress of fabricating tin iodide PSCs with good stability has stimulated the studies of these CHNHSnIbased cells greatly.In the paper,we study the influences of various parameters on the solar cell performance through theoretical analysis and device simulation.It is found in the simulation that the solar cell performance can be improved to some extent by adjusting the doping concentration of the perovskite absorption layer and the electron affinity of the buffer and HTM,while the reduction of the defect density of the perovskite absorption layer significantly improves the cell performance.By further optimizing the parameters of the doping concentration(1.3 × 10cm~3) and the defect density(1 × 10cm~3) of perovskite absorption layer,and the electron affinity of buffer(4.0 eV) and HTM(2.6 eV),we finally obtain some encouraging results of the Jof 31.59 mA/cm~2,Vof 0.92 V,FF of 79.99%,and PCE of 23.36%.The results show that the lead-free CHNHSnIPSC is a potential environmentally friendly solar cell with high efficiency.Improving the Snstability and reducing the defect density of CHNHSnIare key issues for the future research,which can be solved by improving the fabrication and encapsulation process of the cell.展开更多
Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-d...Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.展开更多
In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The...In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.展开更多
In this study,assuming a certain type of wheel loader as the main objective of the research,the performances of the working device of the loader are investigated on the basis of an in-house code.After creating a three...In this study,assuming a certain type of wheel loader as the main objective of the research,the performances of the working device of the loader are investigated on the basis of an in-house code.After creating a three-dimensional model of the working device using Solidworks,this model has been imported into the dynamic simulation software ADAMS,and the simulation problem has been completed by adding the relevant constraints and loadings.The load stress curve relating to the main connecting point of the working device has been obtained in the frame work of this approach and it has been shown that the movement characteristics are compatible with(i.e.,they match)the actual working conditions.The present study may be regarded as a theoretical basis for the design and improvement of the working device of a vast category of wheel loaders.展开更多
Magnetic two-dimensional(2D)van derWaals(vdWs)materials and their heterostructures attract increasing attention in the spintronics community due to their various degrees of freedom such as spin,charge,and energy valle...Magnetic two-dimensional(2D)van derWaals(vdWs)materials and their heterostructures attract increasing attention in the spintronics community due to their various degrees of freedom such as spin,charge,and energy valley,which may stimulate potential applications in the field of low-power and high-speed spintronic devices in the future.This review begins with introducing the long-range magnetic order in 2D vdWs materials and the recent progress of tunning their properties by electrostatic doping and stress.Next,the proximity-effect,current-induced magnetization switching,and the related spintronic devices(such as magnetic tunnel junctions and spin valves)based on magnetic 2D vdWs materials are presented.Finally,the development trend of magnetic 2D vdWs materials is discussed.This review provides comprehensive understandings for the development of novel spintronic applications based on magnetic 2D vdWs materials.展开更多
Numerical simulations by the code of Object-Oriented PIC （Particle-in-Cell） and the Monte Carlo Collision （MCC） method were carried out in order to obtain an insight into the characteristics of plasmas generated b...Numerical simulations by the code of Object-Oriented PIC （Particle-in-Cell） and the Monte Carlo Collision （MCC） method were carried out in order to obtain an insight into the characteristics of plasmas generated by glow discharges in low pressure helium in a four-anode DC glow discharge device. The results show that, the pressure, the external mirror magnetic field, and the virtual breadth of the annular electrode affect the radial distribution of the plasma density and temperature. The simulations are instructive for further experiments.展开更多
Two-dimensional(2D)materials have attracted tremendous interest in view of the outstanding optoelectronic properties,showing new possibilities for future photovoltaic devices toward high performance,high specific powe...Two-dimensional(2D)materials have attracted tremendous interest in view of the outstanding optoelectronic properties,showing new possibilities for future photovoltaic devices toward high performance,high specific power and flexibility.In recent years,substantial works have focused on 2D photovoltaic devices,and great progress has been achieved.Here,we present the review of recent advances in 2D photovoltaic devices,focusing on 2D-material-based Schottky junctions,homojunctions,2D−2D heterojunctions,2D−3D heterojunctions,and bulk photovoltaic effect devices.Furthermore,advanced strategies for improving the photovoltaic performances are demonstrated in detail.Finally,conclusions and outlooks are delivered,providing a guideline for the further development of 2D photovoltaic devices.展开更多
Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field.They have attracted tremendous attention for their extensive appli...Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field.They have attracted tremendous attention for their extensive applications in non-volatile memory,sensors and neuromorphic computing.However,conventional ferroelectric materials face insulating and interfacial issues in the commercialization process.In contrast,two-dimensional(2D)ferroelectric materials usually have excellent semiconductor performance,clean van der Waals interfaces and robust ferroelectric order in atom-thick layers,and hold greater promise for constructing multifunctional ferroelectric optoelectronic devices and nondestructive ultra-high-density memory.Recently,2D ferroelectrics have obtained impressive breakthroughs,showing overwhelming superiority.Herein,firstly,the progress of experimental research on 2D ferroelectric materials is reviewed.Then,the preparation of 2D ferroelectric devices and their applications are discussed.Finally,the future development trend of 2D ferroelectrics is looked at.展开更多
The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with t...The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.展开更多
The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent flui...The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent fluid equations coupled with Poisson equation. In addition, an equivalent-circuit model is coupled to the fluid equations in order to self-consistently determine re-lationship between the instantaneous potential at the rf-biased electrode and the sheath thickness. Two-dimensional profiles of the potential, the ion fluid velocity, and the distributions of the ion and electron densities within the sheath are computed under various discharge conditions, such as the discharge powers and the gas pressures. The results show that the existence of the cylindrical hole on the electrode significantly affects the sheath structure and generates a potential trap in the horizontal direction, which is particularly strong when the sheath thickness is comparable to the depth of the hole. Moreover, it is found that the collisional effects have a significant influence on the sheath characteristics.展开更多
This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equ...This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equations. Numerical method for modelling the short waves is investigated in detail. The forces, such as Coriolis forces, wind stress, atmosphere and bottom friction, are considered. A two-dimensional implicit difference scheme of Boussinesq equations is proposed. The low-reflection outflow open boundary is suggested. By means of this model,both velocity fields of circulation current in a channel with step expansion and the wave diffraction behind a semi-infinite breakwater are computed, and the results are satisfactory.展开更多
To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible an...To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible analysis to evaluate the performance of the device and its relationship with the device parameters. To do that, we designed, fabricated, and tested four devices based on Bi2Te3 and Sb2Te3. To evaluate the accuracy of our analysis, experimental measurements were compared with the numerical simulation performed using COMSOLTM. The two sets of results were found to be in full agreement. This is a proof of the accuracy of our experimental measurements and the credibility of our simulation. The study shows that testing or simulating the devices without heat sink will lead to skewed results. This is because the junction will not hold its temperatures value, but will, instead, automatically change its value to the direction of thermal equilibrium. The study shows also that there is no reciprocity between the input and the output characteristics of the devices. Therefore, a device optimized for cooling and heating may not be automatically optimized for energy harvesting. For heating and cooling, temperature sensitivity should be optimized;while for energy harvesting, voltage sensitivity should be optimized. Using heat sink, our devices achieved a voltage sensitivity of 187.77 μV/K and a temperature sensitivity of 6.12 K/mV.展开更多
A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are...A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.展开更多
With the development of space science and technology,the on-orbit servicing technologies of spacecraft get more and more attention.According to the design criterion of existing spacecraft in orbit module replacement t...With the development of space science and technology,the on-orbit servicing technologies of spacecraft get more and more attention.According to the design criterion of existing spacecraft in orbit module replacement technology,the flexible swap device is designed and the dynamics simulation of institutions by the automatic dynamic analysis of mechanical systems(ADAMS)simulation software is analyzed.Throughout the analysis process,this paper studies the effect of collision force of flexible mechanism and provides a basis for the optimization of flexible plug agencies.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62004151, 62274126, 62274126, 61874083, and 61804113)the China Postdoctoral Science Foundation (Grant No. 2020T130490)。
文摘Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional(2D)(BA)_(2)(MA)_(n-1)Pbn I_(3n+1)(n = 1, 2, 3, 4, 5)(where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells(PSCs) to construct a fourterminal(4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell(n = 4) obtains a power conversion efficiency(PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride(LiF) anti-reflection layer to reduce the surface reflection loss, the current density(J_(sc)) of the top cell is enhanced from 15.56 m A/cm^(2) to 17.09 m A/cm^(2), the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions.
基金support from the National Key Research and Development Program of China(Grant nos.2024YFA1409700 and 2023YFA1407000)the National Natural Science Foundation of China(Grant no.62374158).
文摘In recent years,as the dimensions of the conventional semiconductor technology is approaching the physical limits,while the multifunction circuits are restricted by the relatively fixed characteristics of the traditional metal−oxide−semiconductor field-effect transistors,reconfigurable devices that can realize reconfigurable characteristics and multiple functions at device level have been seen as a promising method to improve integration density and reduce power consumption.Owing to the ultrathin structure,effective control of the electronic characteristics and ability to modulate structural defects,two-dimensional(2D)materials have been widely used to fabricate reconfigurable devices.In this review,we summarize the working principles and related logic applications of reconfigurable devices based on 2D materials,including generating tunable anti-ambipolar responses and demonstrating nonvolatile operations.Furthermore,we discuss the analog signal processing applications of anti-ambipolar transistors and the artificial intelligence hardware implementations based on reconfigurable transistors and memristors,respectively,therefore highlighting the outstanding advantages of reconfigurable devices in footprint,energy consumption and performance.Finally,we discuss the challenges of the 2D materials-based reconfigurable devices.
基金supported by Research and Development Program of Shaanxi Province,China(Grant No.2021ZDLGY10-09)the High-End Foreign Expert Recruitment Program,China(Grant No.G2023170009L)the Science and Technology on Electromechanical Dynamic Control Laboratory,China(Grant No.6142601220111)。
文摘To explore the feasibility of electrospray-based additive manufacturing for thin-film fabrication in zero-or microgravity environments,we conducted numerical simulations of charged droplet behavior under zero-gravity conditions,followed by ground-based experimental validation using an anti-gravity electrospray(AG-ES)strategy.First,simulations of charged droplet deposition during the electrospray process showed that the presence or absence of gravity did not significantly affect deposition behavior.Second,simulations of droplet-substrate collisions indicated that the presence of an electric field could reduce the risk of droplet splashing.Third,simulations of droplet coalescence under zero-gravity conditions demonstrated that an electric field could promote the coalescence of charged droplets.An AG-ES experimental platform featuring an inverted nozzle-substrate configuration was constructed on the ground.Comparative experiments using Rhodamine B solution and TiO_(2)nanoparticle dispersions were performed in both AG-ES and conventional electrospray(ES)modes.The results indicated that the spray cone angle,deposition area,and film morphology were comparable between the two modes.Finally,multilayer alternating-current electroluminescent(ACEL)devices were fabricated via AG-ES using ZnS:Cu/poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP),BaTiO_(3)/polyvinylpyrrolidone(PVP),and silver nanowire(AgNW)inks,achieving a maximum luminance of 66.2 cd/m^(2).This study demonstrates the potential of the electrospray process for functional thin-film fabrication under microgravity conditions.
基金Project supported by the Scientific Research Project of China Three Gorges Corporation(Grant No.202203092)。
文摘Solar Design(https://solardesign.cn/)is an online photovoltaic device simulation and design platform that provides engineering modeling analysis for crystalline silicon solar cells,as well as emerging high-efficiency solar cells such as organic,perovskite,and tandem cells.The platform offers user-updatable libraries of basic photovoltaic materials and devices,device-level multi-physics simulations involving optical–electrical–thermal interactions,and circuit-level compact model simulations based on detailed balance theory.Employing internationally advanced numerical methods,the platform accurately,rapidly,and efficiently solves optical absorption,electrical transport,and compact circuit models.It achieves multi-level photovoltaic simulation technology from“materials to devices to circuits”with fully independent intellectual property rights.Compared to commercial softwares,the platform achieves high accuracy and improves speed by more than an order of magnitude.Additionally,it can simulate unique electrical transport processes in emerging solar cells,such as quantum tunneling,exciton dissociation,and ion migration.
文摘The performance and efficiency of hydraulic excavators heavily depend on the design and optimization of their working devices.The working device,which consists of the boom,arm,and bucket,plays a crucial role in determining the machine's digging capacity,stability,and overall operational efficiency.This paper presents a comprehensive study on the dynamics simulation and optimization of hydraulic excavator working devices.The paper outlines the fundamental principles of dynamic modeling,incorporating multi-body dynamics and hydraulic system analysis.It further explores various simulation techniques to evaluate the performance of the working device under varying operational conditions,including load and hydraulic system effects.The study also addresses performance optimization,focusing on multi-objective optimization methods that balance multiple factors such as energy efficiency,speed,and load capacity.Additionally,the paper discusses key factors influencing performance,such as mechanical design,material properties,and operational conditions.The results of the dynamic simulations and optimization analyses demonstrate potential improvements in operational efficiency and system stability,providing a valuable framework for the design and enhancement of hydraulic excavator working devices.
基金co-supported by China Postdoctoral Science Foundation (20090461314)
文摘Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.
基金supported by the Graduate Student Education Teaching Reform Project,China(Grant No.JG201512)the Young Teachers Research Project of Yanshan University,China(Grant No.13LGB028)
文摘The lead-free perovskite solar cells(PSCs) have drawn a great deal of research interest due to the Pb toxicity of the lead halide perovskite.CHNHSnIis a viable alternative to CHNHPbX,because it has a narrower band gap of 1.3 eV and a wider visible absorption spectrum than the lead halide perovskite.The progress of fabricating tin iodide PSCs with good stability has stimulated the studies of these CHNHSnIbased cells greatly.In the paper,we study the influences of various parameters on the solar cell performance through theoretical analysis and device simulation.It is found in the simulation that the solar cell performance can be improved to some extent by adjusting the doping concentration of the perovskite absorption layer and the electron affinity of the buffer and HTM,while the reduction of the defect density of the perovskite absorption layer significantly improves the cell performance.By further optimizing the parameters of the doping concentration(1.3 × 10cm~3) and the defect density(1 × 10cm~3) of perovskite absorption layer,and the electron affinity of buffer(4.0 eV) and HTM(2.6 eV),we finally obtain some encouraging results of the Jof 31.59 mA/cm~2,Vof 0.92 V,FF of 79.99%,and PCE of 23.36%.The results show that the lead-free CHNHSnIPSC is a potential environmentally friendly solar cell with high efficiency.Improving the Snstability and reducing the defect density of CHNHSnIare key issues for the future research,which can be solved by improving the fabrication and encapsulation process of the cell.
文摘Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.
基金The authors would like to express appreciation for the support of Australia Research Council(IH140100035)Nature Science Foundation of China(51675218)+1 种基金Doctor Starting Foundation of Jiangxi University of Science and Technology(JXXJBS17078)Science and Technology Project of the Education Department of Jiangxi Province(GJJ180426).
文摘In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices.
基金Natural Science Foundation of Hunan Province(No.2018JJ3478)Scientific Research Fund of Hunan Provincial Education Department(No.15C1240)+1 种基金Innovation platform open fund Project(No.16K080)Shao yang guiding science and technology plan project(2019ZD15).
文摘In this study,assuming a certain type of wheel loader as the main objective of the research,the performances of the working device of the loader are investigated on the basis of an in-house code.After creating a three-dimensional model of the working device using Solidworks,this model has been imported into the dynamic simulation software ADAMS,and the simulation problem has been completed by adding the relevant constraints and loadings.The load stress curve relating to the main connecting point of the working device has been obtained in the frame work of this approach and it has been shown that the movement characteristics are compatible with(i.e.,they match)the actual working conditions.The present study may be regarded as a theoretical basis for the design and improvement of the working device of a vast category of wheel loaders.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0206200)the National Natural Science Foundation of China(Grant No.11874409)+2 种基金the Beijing Natural Science Foundation,China(Grant No.Z190009)the Science Center of the National Science Foundation of China(Grant No.52088101)the K.C.Wong Education Foundation(Grant No.GJTD-2019-14).
文摘Magnetic two-dimensional(2D)van derWaals(vdWs)materials and their heterostructures attract increasing attention in the spintronics community due to their various degrees of freedom such as spin,charge,and energy valley,which may stimulate potential applications in the field of low-power and high-speed spintronic devices in the future.This review begins with introducing the long-range magnetic order in 2D vdWs materials and the recent progress of tunning their properties by electrostatic doping and stress.Next,the proximity-effect,current-induced magnetization switching,and the related spintronic devices(such as magnetic tunnel junctions and spin valves)based on magnetic 2D vdWs materials are presented.Finally,the development trend of magnetic 2D vdWs materials is discussed.This review provides comprehensive understandings for the development of novel spintronic applications based on magnetic 2D vdWs materials.
文摘Numerical simulations by the code of Object-Oriented PIC （Particle-in-Cell） and the Monte Carlo Collision （MCC） method were carried out in order to obtain an insight into the characteristics of plasmas generated by glow discharges in low pressure helium in a four-anode DC glow discharge device. The results show that, the pressure, the external mirror magnetic field, and the virtual breadth of the annular electrode affect the radial distribution of the plasma density and temperature. The simulations are instructive for further experiments.
基金supported by the National Natural Science Foundation of China(52322210,52172144,22375069,21825103,and U21A2069)National Key R&D Program of China(2021YFA1200501)+1 种基金Shenzhen Science and Technology Program(JCYJ20220818102215033,JCYJ20200109105422876)the Innovation Project of Optics Valley Laboratory(OVL2023PY007).
文摘Two-dimensional(2D)materials have attracted tremendous interest in view of the outstanding optoelectronic properties,showing new possibilities for future photovoltaic devices toward high performance,high specific power and flexibility.In recent years,substantial works have focused on 2D photovoltaic devices,and great progress has been achieved.Here,we present the review of recent advances in 2D photovoltaic devices,focusing on 2D-material-based Schottky junctions,homojunctions,2D−2D heterojunctions,2D−3D heterojunctions,and bulk photovoltaic effect devices.Furthermore,advanced strategies for improving the photovoltaic performances are demonstrated in detail.Finally,conclusions and outlooks are delivered,providing a guideline for the further development of 2D photovoltaic devices.
基金Project supported by the National Key Research and Development Program of China (Grant No.2022YFB3505301)the National Natural Science Foundation of China (Grant Nos.12241403 and12174237)the Graduate Education Innovation Project in Shanxi Province (Grant No.2021Y484)。
文摘Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field.They have attracted tremendous attention for their extensive applications in non-volatile memory,sensors and neuromorphic computing.However,conventional ferroelectric materials face insulating and interfacial issues in the commercialization process.In contrast,two-dimensional(2D)ferroelectric materials usually have excellent semiconductor performance,clean van der Waals interfaces and robust ferroelectric order in atom-thick layers,and hold greater promise for constructing multifunctional ferroelectric optoelectronic devices and nondestructive ultra-high-density memory.Recently,2D ferroelectrics have obtained impressive breakthroughs,showing overwhelming superiority.Herein,firstly,the progress of experimental research on 2D ferroelectric materials is reviewed.Then,the preparation of 2D ferroelectric devices and their applications are discussed.Finally,the future development trend of 2D ferroelectrics is looked at.
基金supported by National Natural Science Foundation of China (Nos.10635010,10572035)
文摘The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.
基金The project supported by the National Natural Science Foundation of China(No.19975008 and 10275009)and by MOEC (Ministry of Education,China)Grant for Cross-Century Excellent ScholarSupport from the Natural Sciences and Engineering Research Council of C
文摘The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent fluid equations coupled with Poisson equation. In addition, an equivalent-circuit model is coupled to the fluid equations in order to self-consistently determine re-lationship between the instantaneous potential at the rf-biased electrode and the sheath thickness. Two-dimensional profiles of the potential, the ion fluid velocity, and the distributions of the ion and electron densities within the sheath are computed under various discharge conditions, such as the discharge powers and the gas pressures. The results show that the existence of the cylindrical hole on the electrode significantly affects the sheath structure and generates a potential trap in the horizontal direction, which is particularly strong when the sheath thickness is comparable to the depth of the hole. Moreover, it is found that the collisional effects have a significant influence on the sheath characteristics.
基金Supported by the Fund of National Nature Sciences of China
文摘This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equations. Numerical method for modelling the short waves is investigated in detail. The forces, such as Coriolis forces, wind stress, atmosphere and bottom friction, are considered. A two-dimensional implicit difference scheme of Boussinesq equations is proposed. The low-reflection outflow open boundary is suggested. By means of this model,both velocity fields of circulation current in a channel with step expansion and the wave diffraction behind a semi-infinite breakwater are computed, and the results are satisfactory.
文摘To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible analysis to evaluate the performance of the device and its relationship with the device parameters. To do that, we designed, fabricated, and tested four devices based on Bi2Te3 and Sb2Te3. To evaluate the accuracy of our analysis, experimental measurements were compared with the numerical simulation performed using COMSOLTM. The two sets of results were found to be in full agreement. This is a proof of the accuracy of our experimental measurements and the credibility of our simulation. The study shows that testing or simulating the devices without heat sink will lead to skewed results. This is because the junction will not hold its temperatures value, but will, instead, automatically change its value to the direction of thermal equilibrium. The study shows also that there is no reciprocity between the input and the output characteristics of the devices. Therefore, a device optimized for cooling and heating may not be automatically optimized for energy harvesting. For heating and cooling, temperature sensitivity should be optimized;while for energy harvesting, voltage sensitivity should be optimized. Using heat sink, our devices achieved a voltage sensitivity of 187.77 μV/K and a temperature sensitivity of 6.12 K/mV.
基金Supported by the Fundamental Research Funds in Heilongjiang Provincial Universities of China under Grant No 135209312
文摘A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.
文摘With the development of space science and technology,the on-orbit servicing technologies of spacecraft get more and more attention.According to the design criterion of existing spacecraft in orbit module replacement technology,the flexible swap device is designed and the dynamics simulation of institutions by the automatic dynamic analysis of mechanical systems(ADAMS)simulation software is analyzed.Throughout the analysis process,this paper studies the effect of collision force of flexible mechanism and provides a basis for the optimization of flexible plug agencies.
