Tailoring Precursor Chemistry Enabled Room Temperature-Processed Perovskite Films in Ambient Air for Efficient and Stable Solar Cells with Improved Reproducibility

The perovskite solar cells (PSCs) are promising for commercialization and practical application. However, high-quality perovskite films are normally fabricated in inert gas-filled glovebox, followed by thermal annealing, which is energy-consuming and thus not cost-effective. In this study, a simple manufacturing strategy is demonstrated to fabricate the highly-crystalline perovskite films in ambient air (a relative humidity of over ≈50%) at room temperature via blade-coating without the subsequent thermal–annealing. The perovskite precursor chemistry is tailored by solvent engineering via employing 2-methoxyethanol, which can strongly coordinate with ammonium halide species, thus forming highly uniform small-sized colloids and facilitating the homogeneous nucleation and rapid crystallization of perovskite films even at room temperature. The resultant PSCs fabricated with ambient-processed, annealing-free MAPbI₃ perovskite films exhibit a champion efficiency up to 19.16% with negligible hysteresis and improved reproducibility, which is on par with the high-temperature annealed counterparts fabricated in N₂, and represented one of the highest reported efficiencies for the room-temperature processed PSCs in ambient air. The unencapsulated devices show extended lifespan over 1000 h with nearly no efficiency loss.     

云计算信息安全问题探讨

云计算是继个人计算机、互联网之后的第三次信息化革命,给整个信息产业带来巨大的推动力。但是,安全性已经成为云计算面临的最大挑战,它关系着用户对云计算应用的信心。针对目前云计算存在的诸多安全问题,文中提出信息安全风险链条主要包括终端用户、服务商和网络传输3个环节,并着重分析各环节存在的安全问题,最后给出云计算的信息安全框架,以期引起人们对于云计算信息安全问题的重视,并为更好地推进云计算应用提供有效保障。     

时间交替ADC系统的实现

时间交替ADC系统通过几片低速的ADC芯片进行并行交替采样,可以成倍地提高系统的采样频率,同时保持较高的分辨率[1]。但是由于芯片及具体实现过程中一些实际因素的影响,不可避免地会引入通道失配误差[2]。本文利用两片ADC芯片及外围电路来实现时间交替ADC系统,并通过Matlab软件对采样数据进行通道失配误差的估计和校正。Matlab仿真结果表明,该系统的采样率基本上达到了单片ADC的两倍,同时其通道失配误差通过算法校正后得到了有效地消除。     

A Bionic-Gill 3D Hydrogel Evaporator with Multidirectional Crossflow Salt Mitigation and Aquaculture Applications

In recent years, interfacial solar-driven steam generation has gained huge attention as a sustainable and energy-efficient technology. However, salt scaling on and inside the evaporator structure induced by insufficient ion distribution control will lower the evaporation performance and hinder the stability and durability of evaporators. Herein, inspired by the highly efficient salt-expelling property of the gill filaments of large yellow croaker, a bionic-gill 3D hydrogel evaporator is proposed with fabulous multidirectional ion migration controllability. A 3D structure composed of arrayed beaded hollow columns with beaded hollow holes inspired by gill filaments ensuring longitudinal ion backflow and the peristome-mimetic arrayed grooves of microcavities ensuring lateral ion advection is designed and constructed to achieve fabulous multidirectional crossflow salt ion migration, which ensures high evaporation performance for pure water (an evaporation rate of 2.53 kg m⁻² h⁻¹ with an energy efficiency of 99.3%) as well as for high salinity brine (2.11 kg m⁻² h⁻¹ for 25.0 wt.% NaCl solution), with no salt crystallizing after long-term use. Furthermore, the 3D hydrogel evaporator has excellent chemical stability, mechanical properties, folding-irrelevant evaporation performance, and portability so that it can be used for the preliminary desalination of breeding wastewater through the proposed self-circulation koi aquaculture system.     

LTE-A载波聚合下的载波切换分析

多载波聚合技术是LTE-A(LTE-advanced)系统的一个关键技术,它能解决LTE-A系统对带宽资源的需求.由于不同频带的信号传输功率、覆盖范围不尽相同,使得终端在小区间的切换成为难点.本文在LTE切换流程的基础上分析了LTE-A载波聚合环境下的载波切换场景、小区内及小区间的载波切换流程,为了减少多载波切换的失败率,提出了同时向多个符合条件的相邻小区发出切换请求并选择其中最佳小区进行切换的改进思路,同时针对多目标eNB切换方式设计了两种多载波切换方法.     

基于CRF预分割和NSCT的多聚焦图像融合

针对基于多尺度分解的图像融合算法在提高图像模糊区域质量的同时却降低了清晰区域质量的问题,提出了一种结合CRF预分割与NSCT的多聚焦图像融合算法.该算法首先利用条件随机场概率模型对图像进行预分割,将图像预分割为清晰区域、模糊区域和两者的交界区域;然后对图像进行NSCT分解,低频子带系数采用加稀疏约束的非负矩阵分解算法融合,高频子带系数,在交界区域采用方向特征对比度的方法融合,在非交界区域选取清晰度高的系数融合.最后经NSCT逆变换得到最终的融合图像.该方法的融合效果在提高了图像清晰度的同时又有效保持了图像的边缘信息.     

一种WLAN中认知无线电MAC协议的改进

针对认知无线电网络(Cognitive Radio Networks,CRN)特性,提出一种认知无线电MAC协议,该协议通过在认知节点对之间选择最优的信道进行数据传输,当最优信道被主用户占用以后,自动切换到次优信道进行通信,以提高通信成功的概率,达到增大吞吐量的目的。性能分析表明,该MAC协议相对IEEE802.11MAC协议,在吞吐量方面有一定的提高。     

Super Flash型存储器SST39SF020的特性及应用

说明了SST公司新一代Super F1ash型存储器39SF020的性能结构、接口特征、读写程序以及使用中的注意事项。结合实际应用，简述其在和80C196KC单片机构成断路器监测系统中的连接关系。     

Injectable Self-Healing Natural Biopolymer-Based Hydrogel Adhesive with Thermoresponsive Reversible Adhesion for Minimally Invasive Surgery

Biocompatible hydrogel adhesives with multifunctional properties, including injectability, fast self-healing, and suitable on-demand detachment, are highly desired for minimally invasive procedures, but such materials are still lacking. Herein, an injectable self-healing biocompatible hydrogel adhesive with thermoresponsive reversible adhesion based on two extracellular matrix-derived biopolymers, gelatin and chondroitin sulfate, is developed to be used as a surgical adhesive for sealing or reconnecting ruptured tissues. The resulting hydrogels present good self-healing and can be conveniently injected through needles. The strong tissue adhesion at physiological temperatures originates from the Schiff base and hydrogen bonding interactions between the hydrogel and tissue that can be weakened at low temperatures, thereby easily detaching the hydrogel from the tissue in the gelation state. In vivo and ex vivo rat model show that the adhesives can effectively seal bleeding wounds and fluid leakages in the absence of sutures or staples. Specifically, a proof of concept experiment in a damaged rat liver model demonstrates the ability of the adhesives to act as a suitable laparoscopic sealant for laparoscopic surgery. Overall, the adhesive has several advantages, including low cost and ease of production and application that make it an exceptional multifunctional tissue adhesive/sealant, effective in minimally invasive surgical applications.     

频率精确测量方法研究

介绍了几种常见的谱线频率测量方法 ,重点分析了测量频率的相位差法所存在的相位模糊问题 ,提出了一种具有相位模糊修正的谱线频率精确测量方法 ,详细给出了FFT法、相差法和相位模糊修正法的计算机仿真结果 ,得到了具有实际应用价值的结论