基于小波变换的视频编码算法分类研究

在视频通信中,视频编码技术不但要有高的编码效率而且其生成的码流要有多种可伸缩性.在此研究领域.涌现出许多新的编码思想和技术,其中基于小波变换的视频编码算法就是很有发晨前景的技术之一.本文对小波变换视频编码算法进行分类研究.对比分析算法各自的优缺点,指出小波视频编码算法的研究方向.     

Amplification of Cerenkov Luminescence Using Semiconducting Polymers for Cancer Theranostics

The therapeutic efficacy of photodynamic therapy is limited by the ability of light to penetrate tissues. Due to this limitation, Cerenkov luminescence (CL) from radionuclides has recently been proposed as an alternative light source in a strategy referred to as Cerenkov radiation-induced therapy (CRIT). Semiconducting polymer nanoparticles (SPNs) have ideal optical properties, such as large absorption cross-sections and broad absorbance, which can be utilized to harness the relatively weak CL produced by radionuclides. SPNs can be doped with photosensitizers and have ≈100% energy transfer efficiency by multiple energy transfer mechanisms. Herein, an optimized photosensitizer-doped SPN is investigated as a nanosystem to harness and amplify CL for cancer theranostics. It is found that semiconducting polymers significantly amplify CL energy transfer efficiency. Bimodal positron emission tomography (PET) and optical imaging studies show high tumor uptake and retention of the optimized SPNs when administered intravenously or intratumorally. Lastly, it is found that photosensitizer-doped SPNs have excellent potential as a cancer theranostics nanosystem in an in vivo tumor therapy study. This study shows that SPNs are ideally suited to harness and amplify CL for cancer theranostics, which may provide a significant advancement for CRIT that are unabated by tissue penetration limits.     

Biomimetic Hygroscopic Fibrous Membrane with Hierarchically Porous Structure for Rapid Atmospheric Water Harvesting

Sorption-based atmospheric water generation (SAWG) is a promising strategy to alleviate the drinkable water scarcity of arid regions. However, the high-water production efficiency remains challenging due to the sluggish sorption/desorption kinetics. Herein, a composite sorbent@biomimetic fibrous membrane (PPy-COF@Trilayer-LiCl) is reported by mimicking nature's Murray networks, which exhibits outstanding water uptake performance of 0.77–2.56 g g⁻¹ at a wide range of relative humidity of 30%–80% within 50 min and fast water release capacity of over 95% adsorbed water that can be released within 10 min under one sun irradiation. The superior sorption–desorption kinetics of PPy-COF@Trilayer-LiCl are enabled by the novel hierarchically porous structure, which is also the critical factor to lead a directional rapid water transport and vapor diffusion. Moreover, as a proof-of-concept demonstration, a wearable SAWG device is established, which can operate 10 sorption–desorption cycles per day in the outdoor condition and produce a high yield of clean water reaching up to 3.91 kg m⁻² day⁻¹. This study demonstrates a novel strategy for developing advanced solar-driven SAWG materials with efficient water sorption–desorption properties.     

Comprehensively Strengthened Metal-Oxygen Bonds for Reversible Anionic Redox Reaction

Introducing anionic redox in layered oxides is an effective approach to breaking the capacity limit of conventional cationic redox. However, the anionic redox reaction generally suffers from excessive oxidation of lattice oxygen to O₂ and O₂ release, resulting in local structural deterioration and rapid capacity/voltage decay. Here, a Na_0.71Li_0.22Al_0.05Mn_0.73O₂ (NLAM) cathode material is developed by introducing Al³⁺ into the transition metal (TM) sites. Thanks to the strong Al–O bonding strength and small Al³⁺ radius, the TMO₂ skeleton and the holistic TM–O bonds in NLAM are comprehensively strengthened, which inhibits the excessive lattice oxygen oxidation. The obtained NLAM exhibits a high reversible capacity of 194.4 mAh g^-1 at 20 mA g^-1 and decent cyclability with 98.6% capacity retention over 200 cycles at 200 mA g⁻¹. In situ characterizations reveal that the NLAM experiences phase transitions with an intermediate OP4 phase during the charge–discharge. Theoretical calculations further confirm that the Al substitution strategy is beneficial for improving the overlap between Mn 3d and O 2p orbitals. This finding sheds light on the design of layered oxide cathodes with highly reversible anionic redox for sodium storage.     

High-Performing Quasi-2D Perovskite Photodetectors with Efficient Charge Transport Network Built from Vertically Orientated and Evenly Distributed 3D-Like Phases

Quasi-two-dimensional (Q-2D) perovskites are emerging as one of the most promising materials for photodetectors. However, a significant challenge to Q-2D perovskites for photodetection is their insufficient charge transport ability, which is mainly attributed to their hybrid low-dimensional n-phase structure. This study demonstrates that evenly-distributed 3D-like phases with vertical orientation throughout the film can greatly facilitate charge transport and suppress charge recombination, outperforming the prevalent phase structure with a vertical dimension gradient. Based on such a phase structure, a Q-2D Ruddlesden−Popper perovskite self-powered photodetector achieving a combination of exceptional figures-of-merit is realized, including a responsivity of 0.45 AW⁻¹, a peak specific detectivity of 2.3 × 10¹³ Jones, a 156 dB linear dynamic range, and a rise/fall time of 2.89 µs/1.93 µs. The desired phase structure is obtained by utilizing a double-hole transport layer (HTL), combining hydrophobic PTAA and hydrophilic PEDOT: PSS. Besides, the dependence of the hybrid low-dimensional phase structure is also identified on the surface energy of the buried HTL substrate. This study gives insight into the correlation between Q-2D perovskites’ phase structure and performance, providing a valuable design guide for Q-2D perovskite-based photodetectors.     

光纤Bragg光栅地震检波器的研究

由光纤Bragg光栅制成的地震检波器,其采集的传感信息包含在波长上,直接对波长进行调制解调,具有分辨率高、精度高、抗干扰能力强和频带宽等优点.文章研究了光纤Bragg光栅地震检波器,给出其重要参数,并提出了一种新的光纤Bragg光栅地震检波器的解调方案.为光纤Bragg光栅地震检波器的研究以及实际应用提供了依据.     

一种新型的基于无源射频身份识别应答器的电源供给方案

提出了一种基于全集成的无源射频身份识别(RFID)应答器芯片的电源供给方案,并在特许半导体的0.35μm嵌入EEPROM的CMOS工艺线上流片成功.提出的AC/DC和DC/DC电荷泵能够为RFID的应答器芯片提供稳定的工作电压,同时具有极低的功耗和很高的充电效率.还给出了电压倍增器的分析模型、与其他电荷泵的升压原理的比较以及仿真结果和芯片测试结果.     

智能光网络的路由技术

本文比较了传统IP网络和智能光网络路由技术的差别,介绍了满足QoS需求的智能光网络路由技术和适应智能光网络需要的路径选择算法的基本概念,设计基础,着重描述了在基于GMPLS扩展条件下约束最短路径算法的设计思路.     

挠性覆铜板用电解铜箔

概述了电解铜箔"U-WZ箔"和"DFF箔"的开发和特性,它们适用于COF用途等挠性覆铜板的铜箔。     

变频器在变压器绕线机系统中的应用

本文介绍了如何使用普传PI7100变频器的主板端子功能、制动功能及保护功能实现变压器绕线机系统的自动调速控制的工艺要求。着重介绍控制系统如何设计及其工作过程，变频器常见故障及排除措施。