The most significant changes of landscape in a certain period are landscape area changes and spatial changes of landscape patches.Based on transfer matrix and total amount change of landscape area,landscape space tran...The most significant changes of landscape in a certain period are landscape area changes and spatial changes of landscape patches.Based on transfer matrix and total amount change of landscape area,landscape space transfer index and landscape area change index were established,and then applied to analyze plain oasis and desert in Yutian County,Xinjiang Uyghur Nationality Autonomous Region,the results showed that landscape space transfer in this region was drastic,but total landscape area changed only slightly,thus space transfer index was much higher than area change index,which indicated that landscapes in arid area were given with particular spatial undulant features and sensitivity,while man-made landscapes(artificial oasis) are stable and expanding to some extent.With landscape space transfer index as the comprehensive indicator,space transfer intensity of landscape within a certain period can be demonstrated,which is favorable for the comparison of landscape change intensity among different types and within different periods,in addition,some macroscopic change features of landscapes can also be reflected by comprehensively analyzing landscape space transfer index and landscape area change index.展开更多
The damped Helmholtz-Duffing oscillator is a topic of great interest in many different fields of study due to its complex dynamics.By transitioning from conventional continuous differential equations to their fractal ...The damped Helmholtz-Duffing oscillator is a topic of great interest in many different fields of study due to its complex dynamics.By transitioning from conventional continuous differential equations to their fractal counterparts,one gains insights into the system's response under new mathematical frameworks.This paper presents a novel method for converting standard continuous differential equations into their fractal equivalents.This conversion occurs after the nonlinear system is transformed into its linear equivalent.Numerical analyses show that there are several resonance sites in the fractal system,which differ from the one resonance point found in the continuous system.One important finding is that the fractal system loses some of its stabilizing power when decaying behavior is transformed into a diffuse pattern.Interestingly,a decrease in the fractal order in resonance settings shows a stabilizing impact,highlighting the dynamics'complexity inside fractal systems.This endeavor to convert to fractals is a revolutionary technique that is being employed for the first time.展开更多
In this paper,using aδ-doping dual-channel structure and GaAs substrate,a real space transfer transistor(RSTT)is designed and fabricated successfully.It has the standardΛ-shaped negative resistance I-V characteristi...In this paper,using aδ-doping dual-channel structure and GaAs substrate,a real space transfer transistor(RSTT)is designed and fabricated successfully.It has the standardΛ-shaped negative resistance I-V characteristics as well as a level and smooth valley region that the conventional RSTT has.The negative resistance parameters can be varied by changing gate voltage(VGS).For example,the PVCR varies from 2.1 to 10.6 while VGS changes from 0.6 V to 1.0 V.The transconductance for IP(ΔIP=ΔVGS)is 0.3 mS.The parameters of VP,VV and threshold gate voltage(VT)for negative resistance characteristics arising are all smaller than the value reported in the literature.Therefore,this device is suitable for low dissipation power application.展开更多
The components of combustion chamber (cylinder head-cylinder liner-piston assembly-oil film) were taken as a coupled body.Based on the three-dimensional heat transfer numerical simulation of the coupled body,a coupled...The components of combustion chamber (cylinder head-cylinder liner-piston assembly-oil film) were taken as a coupled body.Based on the three-dimensional heat transfer numerical simulation of the coupled body,a coupled three-dimensional calculation model for in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupled method,which implements the coupled three-dimensional simulation of in-cylinder working process and the combustion chamber components.The model was applied in the influence investigation of the space non-uniformity in heat transfer among combustion chamber components on the generation of in-cylinder emissions:NOx.The results showed that the heat transfer space non-uniformity of combustion chamber components directly influences the formation of in-cylinder NOx.The main area being influenced was the accessory area on the wall,while the influence on the generation of NOx in the central area couold be omitted.展开更多
随着电网换相型高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)技术的广泛应用,交直流混联电网的谐波交互问题愈加复杂,建立LCC-HVDC小信号模型是分析换流器交直流谐波耦合特性的重要手段。为此...随着电网换相型高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)技术的广泛应用,交直流混联电网的谐波交互问题愈加复杂,建立LCC-HVDC小信号模型是分析换流器交直流谐波耦合特性的重要手段。为此,基于谐波状态空间理论(harmonic state space, HSS)建立双端12脉动LCC-HVDC小信号模型,不仅考虑了LCC谐波传递特性,还考虑了换流变压器联结方式、控制链路延时等因素的影响。采用模块化思想分别建立各子系统谐波状态空间模型,通过接口矩阵连接为整体,使得LCC的谐波状态空间建模在易于扩展的同时,提高了精确度。最后,给出交直流谐波传递的具体表达式,并通过PSCAD仿真验证模型的准确性。所建模型不仅为后续扩展或接入更为复杂的系统奠定了基础,还可应用于双端LCC系统谐波交互稳定性评估和系统参数优化设计。展开更多
In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type f...In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type fixed point theorem are obtained.展开更多
High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser ir...High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser irradiation, part of the debris material is ablated and provides an impulse to the debris particle. Proper direction of the impulse vector either deflects the object trajectory or forces the debris on a trajectory through the upper atmosphere, where it burns up. Most research concentrates on ground-based laser systems but pays little attention to space-based laser systems.There are drawbacks of a ground-based laser system in cleaning space debris. Therefore the placement of a laser system in space is proposed and investigated. Under assumed conditions,the elimination process of space debris is analyzed. Several factors such as laser repetition frequency, relative movement between the laser and debris, and inclination of debris particles which may exercise influence to the elimination effects are discussed. A project of a space-based laser system is proposed according to the numerical results of a computer study. The proposed laser system can eliminate debris of 1–10 cm and succeed in protecting a space station.展开更多
Intramolecular through-space charge-transfer(TSCT)-enabled thermally activated delayed fluorescence(TADF)emitters have shown exceptional potential for advancing organic light-emitting diode(OLED)technologies,owing to ...Intramolecular through-space charge-transfer(TSCT)-enabled thermally activated delayed fluorescence(TADF)emitters have shown exceptional potential for advancing organic light-emitting diode(OLED)technologies,owing to their efficient utilization of triplet excitons and optimized photophysical properties.To date,the intrinsic correlation among molecular geometries,intramolecular non-covalent interactions,and photophysical properties in TSCT-TADF emitters remains unconfirmed,and this study theoretically clarifies this critical correlation.Specifically,through integrating molecular engineering,screening strategies,first-principles calculations,energy decomposition analysis,and statistical modeling,we systematically investigated 24 experimentally reported TADF molecules,and 54 newly designed structures in both solution and thin-film environments.We establish a clear geometric criterion for high-efficiency TSCT-TADF emitters:donor-acceptor(D-A)dihedral angles below 25°and interfragment distances within 4Å—conditions validated by both theoretical predictions and experimental evidence.Based on this insight,we designed two novel molecular libraries with benzene-or carbazole-derivative bridges,using O-bridged triphenylamine(DPXZ)as the donor and quinolino[3,2,1-de]acridine-5,9-dione(QAO)as the acceptor.Our calculations confirm that sub-25°D-A dihedral angles correlate with exceptional delayed fluorescence efficiency,with predictions reaching up to 96%and an average of 70%for the new thin film systems.This study provides a rational design strategy for high-performance TSCT-TADF emitters,significantly advancing the molecular-level understanding of through-space interactions and accelerating the discovery of tailored,efficient OLED materials.展开更多
基金Supported by National Natural Science Foundation(40661002)Project of National Natural Science Youth Foundation(40701188)Highlevel Talents Initiation Project of Shihezi University(RCZX200693)~~
文摘The most significant changes of landscape in a certain period are landscape area changes and spatial changes of landscape patches.Based on transfer matrix and total amount change of landscape area,landscape space transfer index and landscape area change index were established,and then applied to analyze plain oasis and desert in Yutian County,Xinjiang Uyghur Nationality Autonomous Region,the results showed that landscape space transfer in this region was drastic,but total landscape area changed only slightly,thus space transfer index was much higher than area change index,which indicated that landscapes in arid area were given with particular spatial undulant features and sensitivity,while man-made landscapes(artificial oasis) are stable and expanding to some extent.With landscape space transfer index as the comprehensive indicator,space transfer intensity of landscape within a certain period can be demonstrated,which is favorable for the comparison of landscape change intensity among different types and within different periods,in addition,some macroscopic change features of landscapes can also be reflected by comprehensively analyzing landscape space transfer index and landscape area change index.
文摘The damped Helmholtz-Duffing oscillator is a topic of great interest in many different fields of study due to its complex dynamics.By transitioning from conventional continuous differential equations to their fractal counterparts,one gains insights into the system's response under new mathematical frameworks.This paper presents a novel method for converting standard continuous differential equations into their fractal equivalents.This conversion occurs after the nonlinear system is transformed into its linear equivalent.Numerical analyses show that there are several resonance sites in the fractal system,which differ from the one resonance point found in the continuous system.One important finding is that the fractal system loses some of its stabilizing power when decaying behavior is transformed into a diffuse pattern.Interestingly,a decrease in the fractal order in resonance settings shows a stabilizing impact,highlighting the dynamics'complexity inside fractal systems.This endeavor to convert to fractals is a revolutionary technique that is being employed for the first time.
文摘In this paper,using aδ-doping dual-channel structure and GaAs substrate,a real space transfer transistor(RSTT)is designed and fabricated successfully.It has the standardΛ-shaped negative resistance I-V characteristics as well as a level and smooth valley region that the conventional RSTT has.The negative resistance parameters can be varied by changing gate voltage(VGS).For example,the PVCR varies from 2.1 to 10.6 while VGS changes from 0.6 V to 1.0 V.The transconductance for IP(ΔIP=ΔVGS)is 0.3 mS.The parameters of VP,VV and threshold gate voltage(VT)for negative resistance characteristics arising are all smaller than the value reported in the literature.Therefore,this device is suitable for low dissipation power application.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 50576008,50876016,and 51006015)
文摘The components of combustion chamber (cylinder head-cylinder liner-piston assembly-oil film) were taken as a coupled body.Based on the three-dimensional heat transfer numerical simulation of the coupled body,a coupled three-dimensional calculation model for in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupled method,which implements the coupled three-dimensional simulation of in-cylinder working process and the combustion chamber components.The model was applied in the influence investigation of the space non-uniformity in heat transfer among combustion chamber components on the generation of in-cylinder emissions:NOx.The results showed that the heat transfer space non-uniformity of combustion chamber components directly influences the formation of in-cylinder NOx.The main area being influenced was the accessory area on the wall,while the influence on the generation of NOx in the central area couold be omitted.
文摘随着电网换相型高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)技术的广泛应用,交直流混联电网的谐波交互问题愈加复杂,建立LCC-HVDC小信号模型是分析换流器交直流谐波耦合特性的重要手段。为此,基于谐波状态空间理论(harmonic state space, HSS)建立双端12脉动LCC-HVDC小信号模型,不仅考虑了LCC谐波传递特性,还考虑了换流变压器联结方式、控制链路延时等因素的影响。采用模块化思想分别建立各子系统谐波状态空间模型,通过接口矩阵连接为整体,使得LCC的谐波状态空间建模在易于扩展的同时,提高了精确度。最后,给出交直流谐波传递的具体表达式,并通过PSCAD仿真验证模型的准确性。所建模型不仅为后续扩展或接入更为复杂的系统奠定了基础,还可应用于双端LCC系统谐波交互稳定性评估和系统参数优化设计。
基金This work is supported by the Scientific Research Foundation of Bijie University.
文摘In this article, a Ky Fan matching theorem for transfer compactly open covers is established. As applications, a Fan-Browder coincidence theorem, a Ky Fan best approximation theorem and a Brouwer-Schauder-Rothe type fixed point theorem are obtained.
基金supported by the National Natural Science Foundation of China(No:11102234)Provincial Level Project of China
文摘High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser irradiation, part of the debris material is ablated and provides an impulse to the debris particle. Proper direction of the impulse vector either deflects the object trajectory or forces the debris on a trajectory through the upper atmosphere, where it burns up. Most research concentrates on ground-based laser systems but pays little attention to space-based laser systems.There are drawbacks of a ground-based laser system in cleaning space debris. Therefore the placement of a laser system in space is proposed and investigated. Under assumed conditions,the elimination process of space debris is analyzed. Several factors such as laser repetition frequency, relative movement between the laser and debris, and inclination of debris particles which may exercise influence to the elimination effects are discussed. A project of a space-based laser system is proposed according to the numerical results of a computer study. The proposed laser system can eliminate debris of 1–10 cm and succeed in protecting a space station.
基金supported by the National Key R&D Program of China(2021YFB3500400(Meng L))the Self-deployment Project Research Program of Haixi Institutes+7 种基金Chinese Academy of Sciences(CXZX-2022-GH02(Meng L))the National Natural Science Foundation of China(52073286 and 22275185(Lu CZ))the Natural Science Foundation of Fujian Province(2023J01215(Meng L))the Supporting Project of Fujian Province for"Science and Technology Service Network Initiative,CAS"(2023T3024(Meng L))the Xiamen Institute of Rare Earth Materials(XMIREM)Autonomously Deployment Project(2023GG01(Lu CZ))the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ115(Lu CZ))the Opening Foundation of State Key Laboratory of Physical Chemistry of Solid SurfacesXiamen University(202419(Meng L))。
文摘Intramolecular through-space charge-transfer(TSCT)-enabled thermally activated delayed fluorescence(TADF)emitters have shown exceptional potential for advancing organic light-emitting diode(OLED)technologies,owing to their efficient utilization of triplet excitons and optimized photophysical properties.To date,the intrinsic correlation among molecular geometries,intramolecular non-covalent interactions,and photophysical properties in TSCT-TADF emitters remains unconfirmed,and this study theoretically clarifies this critical correlation.Specifically,through integrating molecular engineering,screening strategies,first-principles calculations,energy decomposition analysis,and statistical modeling,we systematically investigated 24 experimentally reported TADF molecules,and 54 newly designed structures in both solution and thin-film environments.We establish a clear geometric criterion for high-efficiency TSCT-TADF emitters:donor-acceptor(D-A)dihedral angles below 25°and interfragment distances within 4Å—conditions validated by both theoretical predictions and experimental evidence.Based on this insight,we designed two novel molecular libraries with benzene-or carbazole-derivative bridges,using O-bridged triphenylamine(DPXZ)as the donor and quinolino[3,2,1-de]acridine-5,9-dione(QAO)as the acceptor.Our calculations confirm that sub-25°D-A dihedral angles correlate with exceptional delayed fluorescence efficiency,with predictions reaching up to 96%and an average of 70%for the new thin film systems.This study provides a rational design strategy for high-performance TSCT-TADF emitters,significantly advancing the molecular-level understanding of through-space interactions and accelerating the discovery of tailored,efficient OLED materials.
