Influence of the ratio of gate length to drain-to-source distance on the electron mobility in AlGaN/AlN/GaN heterostructure field-effect transistors

ABSTRACT: Using measured capacitance-voltage curves with different gate lengths and current-voltage characteristics at low drain-to-source voltage for the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) of different drain-to-source distances, we found that the dominant scattering mechanism in the AlGaN/AlN/GaN HFETs is determined by the ratio of gate length to drain-to-source distance. For the devices with small ratio (here less than 1/2), the polarization Coulomb field scattering dominates the electron mobility. However, for the devices with large ratio (here more than 1/2), the LO phonon scattering and interface roughness scattering are dominant. The reason is closely related to the polarization Coulomb field scattering.     

Operational and complete approaches to belief revision

Two operational approaches to belief revision are presented in this paper.The rules of R-calculus are modified in order to deduce all the maximal consistent subsets.Another set of given in order to deduce all the minimal inconsistent subsets.Then a procedure,which can generate all the maximal consistent subsets,is presented.They are complete approaches,since all the maximal consistent subsets can be deduced or generated.In this paper,only the case of propositional logic is considered.     

浅谈山区建筑的结构设计

结合工程实例,分析了山区建筑的结构特点,阐述了在该类工程设计中需要注意的问题,提出了相应的设计建议.     

基于板模型对采场底板破坏与突水机理研究

以岩层控制中的关键层理论为指导,应用弹性板理论求解分析了底板关键层的破断,最后结合工程实例对底板突水最危险点作了预测分析。     

Easily Available High-Performance Organic Solar Cells by Regulating Phenylalkyl Side Groups of Non-Fused Ring Electron Acceptors

Although non-fused ring electron acceptors (NFREAs) have received increasing attention due to their relatively low synthetic costs, the achievement of high efficiencies strongly depends on tedious pre- or/and post-treatments to refine the active layers, which in turn greatly increase fabrication complexity and expense of organic solar cells (OSCs). Nowadays most of the available as-cast devices based on NFREAs are below 12% efficiencies. Herein, phenylalkyl category side groups (CnPh) are employed to construct new NFREAs named BOR-CnPh (n = 3, 4, and 6), which exhibit inherently decent molecular aggregation and thus exclude additional treatments from device fabrication. The modified alkyl spacers of CnPh side groups not only trigger different aggregation of the acceptors, but also regulate the interaction conformations of donor (D) and acceptor (A), and thus D/A interactions. Encouragingly, the pristine PBDB-T:BOR-C4Ph blend delivers intrinsic fibrous networks with dominating face-on orientation, which yields an optimal efficiency up to 13.12%, and ranks as the highest value among as-cast OSCs based on NFREAs. This research provides a practical strategy to control molecular aggregations, interactions, and pristine heterojunction morphologies for easily available and high-performance organic photovoltaics.     

激光制导炸弹半实物仿真模型的校核与验证

为了检验激光制导炸弹半实物仿真模型的准确性,建立了激光制导炸弹的飞行动力学、运动学方程及其计算程序,将激光制导炸弹、激光目标模拟器、五轴转台与仿真计算机联接,构建半实物仿真系统,进行半实物仿真实验,获得仿真数据;运用制导炸弹的概念和飞行力学理论校核仿真模型的正确性;利用无人机挂载激光制导炸弹实施投弹试验,分析、对比试验数据与仿真数据,验证仿真模型的准确性.     

飞秒激光在生物医学中的应用

飞秒激光问世以来,其优越的特性受到越来越多的重视。本文要介绍和评述了飞秒激光的特点及其在现代医学和生物学中的各种应用。     

光网络实时连接恢复中资源分配死锁解除方法

智能光网络的到来,使光网络资源分布式并行分配死锁问题异常突出,对连接恢复的性能影响非常大.针对连接需要快速建立和恢复的特性,提出一种基于连接地址优先级的光网络资源分布式并行分配死锁解除方法,能够降低连接的建立和连接恢复的阻塞率,在高负载下可以缩短连接恢复的时间.     

Photogenerated Defect-Transit Dual S-Scheme Charge Separation for Highly Efficient Hydrogen Production

The rational design of a step-scheme (S-scheme) heterojunctions in hybrid semiconductors by avoiding unwanted charge transport paths is considered as an attractive way to achieve high photocatalytic activity in hydrogen evolution reaction (HER). Here, a dual S-scheme heterojunction formed in the lychee-shaped W₁₈O₄₉/CdWO₄/CdS nanostructures is proposed for improving the photocatalytic performance in HER under visible light irradiation. The remarkable activity in photocatalytic HER of W₁₈O₄₉/CdWO₄/CdS is attributed to the unique structure and effective charge separation by the photoinduced defect-transit dual S-scheme mechanism and strong internal electric field. The measurements of X-ray photoelectron spectroscopy (XPS), femtosecond transient absorption (fs-TA) spectroscopy, and electron paramagnetic resonance (EPR) further confirm the photoinduced carrier transfer pathways following the dual S-scheme mechanism. This research can provide a new strategy for designing the dual S-scheme heterojunctions to improve photocatalytic performance through the defect band structure engineering.     

New-Generation Anion-Pillared Metal–Organic Frameworks with Customized Cages for Highly Efficient CO2 Capture

The rational design of porous materials for CO₂ capture under realistic process conditions is highly desirable. However, trade-offs exist among a nanopore's capacity, selectivity, adsorption heat, and stability. In this study, a new generation of anion-pillared metal-organic frameworks (MOFs) are reported with customizable cages for benchmark CO₂ capture from flue gas. The optimally designed TIFSIX-Cu-TPA exhibits a high CO₂ capacity, excellent CO₂/N₂ selectivity, high thermal stability, and chemical stability in acid solution and acidic atmosphere, as well as modest adsorption heat for facile regeneration. Additionally, the practical separation performance of the synthesized MOFs is demonstrated by breakthrough experiments under various process conditions. A highly selective separation is achieved at 298–348 K with the impressive CO₂ capacity of 2.1–1.4 mmol g⁻¹. Importantly, the outstanding performance is sustained under high humidity and over ten repeat process cycles. The molecular mechanism of MOF's CO₂ adsorption is further investigated in situ by CO₂ dosed single crystal structure and theoretical calculations, highlighting two separate binding sites for CO₂ in small and large cages featured with high CO₂ selectivity and loading, respectively. The simultaneous adsorption of CO₂ inside these two types of interconnected cages accounts for the high performance of these newly designed anionic pillar-caged MOFs.