In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A s...In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration,IPA concentration,etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results show that with TMAH concentration increases,the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore,etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally,smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of Ga N-based light emitting diode(LED) devices.展开更多
The Mohorovicic discontinuity(Moho)boundary separating the Earth’s crust and mantle reflects the evolutionary trajectory of the Earth’s crust,yielding crucial insights into crustal formation,tectonic evolution,and p...The Mohorovicic discontinuity(Moho)boundary separating the Earth’s crust and mantle reflects the evolutionary trajectory of the Earth’s crust,yielding crucial insights into crustal formation,tectonic evolution,and profound dynamic processes.However,the prevailing Moho models for China and its adjacent areas suffer from limited accuracy,owing to the irregular and sparse distribution of seismic data collection.In this study,we employ gravimetric data to derive Moho depth,and employ Bott’s regularization method,integrating gravity and seismic data to reconstruct the Moho structure with high precision in a three-dimensional framework across China and its adjacent areas.By optimizing gravity potential field separation and interface inversion techniques,we present a detailed and accurate zoning scheme for classifying China and its adjacent areas into 35 gradient belts,6 primary tectonic units,and 35 secondary tectonic units,based on the spatial distribution characteristics of the Moho discontinuity.Notably,our tectonic pattern division results surpass previous studies in terms of resolution,providing a wealth of tectonic information.Leveraging the Moho depth model of China and its adjacent areas,we discuss orogenic belts,sedimentary basins,fault systems,plate boundaries,and land-sea coupled tectonic patterns.We meticulously summarize the Moho depth distribution characteristics of each tectonic unit,while exploring the macrostructural framework and geological significance of the study area.Our findings highlight the close relationship between China and its adjacent areas Moho depth model and deep geodynamics,elucidating the tectonic evolution both between and within tectonic plates,as well as the tectonic effects induced by mantle dynamics.These insights have crucial implications for the study of deep geodynamics in China and its adjacent areas.展开更多
The literature suggests inconsistent evidence regarding the influence of danger on prosocial behavior.We explore this issue through a nationwide survey of 8567 households in China during the COVID-19 Omicron variant o...The literature suggests inconsistent evidence regarding the influence of danger on prosocial behavior.We explore this issue through a nationwide survey of 8567 households in China during the COVID-19 Omicron variant outbreak in 2022.In a zero-COVID policy,China chose to quarantine all neighborhoods with viral infections.The almost random presence of infected cases provides an opportunity to examine the relationship between the proximity of danger(i.e.potential Omicron infection)and the prosocial behavior of residents in quarantine zones.For the first time,we find an inverted U-shape relationship:residents exhibit a stronger prosocial behavior when living closer to infected cases in the neighborhood,but this positive effect diminishes when they are too close to each other.Furthermore,such non-linear relationship is salient in residents’interpersonal helping but not in their cooperative behavior.Policymakers should be mindful of the different prosocial responses and target their efforts to help communities navigate quarantine periods more effectively.展开更多
In this paper, a new intelligent control method is introduced, which combines stipulations, optimal control method with knowledge based control. Using nonlinear programming method and expert experience for the compli...In this paper, a new intelligent control method is introduced, which combines stipulations, optimal control method with knowledge based control. Using nonlinear programming method and expert experience for the complicated nonlinear object, the good control result can be achieved. The effect of this method is shown by a simulation of three stage inverted pendulums.展开更多
This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of ...This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.展开更多
Efficiently modulating the velocity distribution and flow pattern of non-Newtonian fluids is a critical challenge in the context of dual shaft eccentric mixers for process intensification,posing a significant barrier ...Efficiently modulating the velocity distribution and flow pattern of non-Newtonian fluids is a critical challenge in the context of dual shaft eccentric mixers for process intensification,posing a significant barrier for the existing technologies.Accordingly,this work reports a convenient strategy that changes the kinetic energy to controllably regulate the flow patterns from radial flow to axial flow.Results showed that the desired velocity distribution and flow patterns could be effectively obtained by varying the number and structure of baffles to change kinetic energy,and a more uniform velocity distribution,which could not be reached normally in standard baffle dual shaft mixers,was easily obtained.Furthermore,a comparative analysis of velocity and shear rate distributions is employed to elucidate the mechanism behind the generation of flow patterns in various dual-shaft eccentric mixers.Importantly,there is little difference in the power number of the laminar flow at the same Reynolds number,meaning that the baffle type has no effect on the power consumption,while the power number of both unbaffle and U-shaped baffle mixing systems decreases compared with the standard baffle mixing system in the transition flow.Finally,at the same rotational condition,the dimensionless mixing time of the U-shaped baffle mixing system is 15.3%and 7.9%shorter than that of the standard baffle and the unbaffle mixing system,respectively,which shows the advantage of the U-shaped baffle in stirring rate.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51472229,61422405,51202238,61306051 and 61474109)the “100 Talent Program” of Chinese Academy of Sciencesthe Opening Funding of State Key Lab of Silicon Materials(No.SKL2014-4)
文摘In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration,IPA concentration,etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results show that with TMAH concentration increases,the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore,etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally,smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of Ga N-based light emitting diode(LED) devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.42474121 and 42192535)the Basic Frontier Science Research Program of the Chinese Academy of Sciences(Grant No.ZDBS-LY-DQC028).
文摘The Mohorovicic discontinuity(Moho)boundary separating the Earth’s crust and mantle reflects the evolutionary trajectory of the Earth’s crust,yielding crucial insights into crustal formation,tectonic evolution,and profound dynamic processes.However,the prevailing Moho models for China and its adjacent areas suffer from limited accuracy,owing to the irregular and sparse distribution of seismic data collection.In this study,we employ gravimetric data to derive Moho depth,and employ Bott’s regularization method,integrating gravity and seismic data to reconstruct the Moho structure with high precision in a three-dimensional framework across China and its adjacent areas.By optimizing gravity potential field separation and interface inversion techniques,we present a detailed and accurate zoning scheme for classifying China and its adjacent areas into 35 gradient belts,6 primary tectonic units,and 35 secondary tectonic units,based on the spatial distribution characteristics of the Moho discontinuity.Notably,our tectonic pattern division results surpass previous studies in terms of resolution,providing a wealth of tectonic information.Leveraging the Moho depth model of China and its adjacent areas,we discuss orogenic belts,sedimentary basins,fault systems,plate boundaries,and land-sea coupled tectonic patterns.We meticulously summarize the Moho depth distribution characteristics of each tectonic unit,while exploring the macrostructural framework and geological significance of the study area.Our findings highlight the close relationship between China and its adjacent areas Moho depth model and deep geodynamics,elucidating the tectonic evolution both between and within tectonic plates,as well as the tectonic effects induced by mantle dynamics.These insights have crucial implications for the study of deep geodynamics in China and its adjacent areas.
基金supported in part by the National Natural Science Foundation of China(72033003,12071088,91846302 and 71973107).
文摘The literature suggests inconsistent evidence regarding the influence of danger on prosocial behavior.We explore this issue through a nationwide survey of 8567 households in China during the COVID-19 Omicron variant outbreak in 2022.In a zero-COVID policy,China chose to quarantine all neighborhoods with viral infections.The almost random presence of infected cases provides an opportunity to examine the relationship between the proximity of danger(i.e.potential Omicron infection)and the prosocial behavior of residents in quarantine zones.For the first time,we find an inverted U-shape relationship:residents exhibit a stronger prosocial behavior when living closer to infected cases in the neighborhood,but this positive effect diminishes when they are too close to each other.Furthermore,such non-linear relationship is salient in residents’interpersonal helping but not in their cooperative behavior.Policymakers should be mindful of the different prosocial responses and target their efforts to help communities navigate quarantine periods more effectively.
文摘In this paper, a new intelligent control method is introduced, which combines stipulations, optimal control method with knowledge based control. Using nonlinear programming method and expert experience for the complicated nonlinear object, the good control result can be achieved. The effect of this method is shown by a simulation of three stage inverted pendulums.
文摘This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.
基金supported by the National Natural Science Foundation of China(22078030,52021004)Natural Science Foundation of Chongqing(2022NSCO-LZX0014)+1 种基金Fundamental Research Funds for the Central Universities(2022CDJQY-005,2023CDJXY-047)National Key Research and Development Project(2022YFC3901204)。
文摘Efficiently modulating the velocity distribution and flow pattern of non-Newtonian fluids is a critical challenge in the context of dual shaft eccentric mixers for process intensification,posing a significant barrier for the existing technologies.Accordingly,this work reports a convenient strategy that changes the kinetic energy to controllably regulate the flow patterns from radial flow to axial flow.Results showed that the desired velocity distribution and flow patterns could be effectively obtained by varying the number and structure of baffles to change kinetic energy,and a more uniform velocity distribution,which could not be reached normally in standard baffle dual shaft mixers,was easily obtained.Furthermore,a comparative analysis of velocity and shear rate distributions is employed to elucidate the mechanism behind the generation of flow patterns in various dual-shaft eccentric mixers.Importantly,there is little difference in the power number of the laminar flow at the same Reynolds number,meaning that the baffle type has no effect on the power consumption,while the power number of both unbaffle and U-shaped baffle mixing systems decreases compared with the standard baffle mixing system in the transition flow.Finally,at the same rotational condition,the dimensionless mixing time of the U-shaped baffle mixing system is 15.3%and 7.9%shorter than that of the standard baffle and the unbaffle mixing system,respectively,which shows the advantage of the U-shaped baffle in stirring rate.
