单帧图像的超分辨率技术进展

单帧图像超分辨率重建是就是由一幅降质的含噪的低分辨率图像来估计一幅高分辨率图像。列举了当前研究的几种主要算法,从峰值信噪比、框架相似性和边缘稳健性的标准来加以比较。最后的结果显示RS算法性能最优,这也符合主观评价标准。     

Bis(perchlorocatecholato)silane—A Neutral Silicon Lewis Super Acid

No neutral silicon Lewis super acids are known to date. We report on the synthesis of bis(perchlorocatecholato)silane and verify its Lewis super acidity by computation (DLPNO‐CCSD(T)) and experiment (fluoride abstraction from SbF₆^?). The exceptional affinity towards donors is further demonstrated by, for example, the characterization of an unprecedented SiO₄F₂ dianion and applied in the first hydrodefluorination reaction catalyzed by a neutral silicon Lewis acid. Given the strength and convenient access to this new Lewis acid, versatile applications might be foreseen.     

基于区块链的防特权账号篡改审计系统

审计系统通过对客户网络设备、安全设备、主机和应用系统日志等数据进行全面的标准化处理,及时发现各种安全威胁、异常行为事件,为管理人员提供全局视角,确保客户业务的不间断运营安全;通过基于国际标准化的关联分析引擎,为客户提供全维度、跨设备、细粒度的关联分析,透过事件的表象真实还原事件背后的信息,为客户提供真正可信赖的事件追责依据和业务运行的深度安全,在整个信息安全防御体系中占有重要的位置。然而,现有的审计系统存在特权账号权限过大问题,其能对审计记录进行修改,降低了审计系统的能效。针对该问题,利用区块链技术的不可篡改性质,提出了一个防篡改审计系统。审计数据被上传至区块链中,利用属性基加密技术对数据进行保护,并实现细粒度访问控制。最后,通过批处理、预处理、哈希链等技术,消除由于使用区块链技术和属性基加密技术而带来的效率问题。     

一种超级电容储能的双向逆变电路及其控制策略

为解决数控机床加工中意外掉电退刀、伺服单元外接制动电阻产生能耗等问题,提出了一种超级电容储能的双向逆变电路,使得伺服系统在突然断电状态下,储能模块能够继续短时地给数控机床系统供电,完成断电回退的功能。该电路可以提供更高的输出电压和占空比,且在应用中可以取消伺服单元外接制动电阻而将制动能量循环利用,同时提出了相应的控制策略。该电路包括Buck/Boost电路、信号采样电路、PWM逻辑控制电路和互锁驱动电路,通过调节两路互为180°的PWM波占空比及充、放电信号来实现升、降压闭环控制,从而完成能量的双向传递。该拓扑简单、高效,性能稳定,以最少的功率器件实现大功率转换及输出。最后,实验波形验证了所提方案的可靠性。     

The Dynamic Emission Zone in Sandwich Polymer Light‐Emitting Electrochemical Cells

In light‐emitting electrochemical cells (LECs), the position of the emission zone (EZ) is not predefined via a multilayer architecture design, but governed by a complex motion of electrical and ionic charges. As a result of the evolution of doped charge transport layers that enclose a dynamic intrinsic region until steady state is reached, the EZ is often dynamic during turn‐on. For thick sandwich polymer LECs, a continuous change of the emission color provides a direct visual indication of a moving EZ. Results from an optical and electrical analysis indicate that the intrinsic zone is narrow at early times, but starts to widen during operation, notably well before the electrical device optimum is reached. Results from numerical simulations demonstrate that the only precondition for this event to occur is that the mobilities of anions (μ_a) and cations (μ_c) are not equal, and the direction of the EZ shift dictates μ_c > μ_a. Quantitative ion profiles reveal that the displacement of ions stops when the intrinsic zone stabilizes, confirming the relation between ion movement and EZ shift. Finally, simulations indicate that the experimental current peak for constant‐voltage operation is intrinsic and the subsequent decay does not result from degradation, as commonly stated.     

A self‐adaptive algorithm for super‐peer selection considering the mobility of peers in cognitive mobile peer‐to‐peer networks

Cognitive peer‐to‐peer networks are obtained from a combination of cognitive networking concepts and peer‐to‐peer networks. These networks are able to improve their performance while operating under dynamic and unknown environments. A cognitive peer‐to‐peer network tries to learn an appropriate configuration for itself considering the unknown physical properties of peers. Cognitive mobile peer‐to‐peer networks refer to cognitive peer‐to‐peer networks which are built over mobile ad hoc networks. In these networks, heterogeneity of the mobility of peers and resource limitation in wireless networks create challenges for network management algorithms. Because of the dynamicity of these networks, the management algorithms should be designated in self‐adaptive manner. In one type of these networks, some peers, called super‐peers, undertake to perform network managerial tasks. The mobility of peers leads to connection failure among peers and reselection of new super‐peers. Therefore, the selection of super‐peers, due to their influential role, requires an algorithm that considers the peers' mobility. Up to now, no self‐adaptive algorithm has been designated for super‐peer selection considering the mobility of peers in a self‐adaptive manner. This paper proposes M‐SSBLA, a self‐adaptive algorithm for super‐peer selection considering the mobility of peers based on learning automata. The proposed algorithm is obtained from cooperation between a learning automata‐based cognitive engine and MIS. MIS is a well‐known super‐peer selection algorithm in mobile peer‐to‐peer networks. We compared the proposed algorithm with recently reported algorithms, especially for a network with high mobility. Simulation results show that the proposed algorithm can cover maximum ordinary‐peer with a few super‐peer and improve robustness against super‐peer failures while decreasing maintenance overhead.     

Strategic Engineering of Sub-5 nm Dyes@CDs Nanoassemblies Platform for Super Resolution Imaging

The design and construction of fluorescence probes with small size, high quantum yield, photostability, and solubility in an aqueous solution to achieve biomarker have become a focus of interest in super-resolution bioimaging application. Herein, four kinds of GFP-like supramolecular nanoassemblies (SNAs) are constructed in a very facile manner by the host–guest interaction between isopercolic acid derivatives (IADs) and cyclodextrin (CD). ¹H NMR, Fourier transform infrared spectroscopy (FT-IR) and single crystal structure well prove the formation of SNAs. Moreover, compared to the initial state, the fluorescence quantum yield of the SNAs is dramatically improved through suppressing nonradiative relaxation pathways and shielding quenchers. The bimolecular exciton–exciton annihilation (bmEA) process under the high pumping fluence has been suppressed effectively. Both the improved gain and the reduced loss facilitate the buildup of stimulated emission and enable the high stimulated emission efficiency of these SNAs. Sub-5 nm IADs@β-CDs-mediated STED imaging exhibits excellent stimulated emission depletion (STED) performance: high photostability, low saturation intensity ( ≈ 0.50 MW cm⁻²), and high resolution (30 nm) under P_STED-775 nm of 109 MW cm⁻². This supramolecular strategy avoids the tedious molecular synthesis process and paves a new pathway for insights into building up novel high-performance STED probes.     

Helical polyacetylene—Origins and synthesis

We present the origins and synthesis of helical polyacetylene (H‐PA) by focusing on its peculiar spiral morphology. Interfacial polymerization of acetylene was carried out in an asymmetric reaction field consisting of chiral nematic liquid crystal (N*‐LC) and Ziegler–Natta catalyst. As the N*‐LC is composed of nematic liquid crystal and a chiral compound such as a binaphthyl derivative with either the R‐ or S‐configuration, the screw directions of the polyacetylene chain and fibril bundle—and even the spiral morphology—are rigorously controlled by the chirality of the selected compound. Interestingly, the screw directions of the fibril and the bundle in H‐PA were found to be opposite to that of N*‐LC. It is worthwhile to emphasize that the hierarchical spiral morphology involving the primary to higher order structure is generated in a synthetic polymer such as polyacetylene by using N*‐LC as an asymmetric polymerization solvent. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 395–406; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20163     

超级微波消解-电感耦合等离子体发射光谱（ICP-OES）法测定土壤中18种元素

为提高土壤多元素同时检测的效率,采用超级微波消解-电感耦合等离子体发射光谱法测定土壤中钾、钠、钙、镁、铜、铁、锰、锌、磷、硫、硼、砷、镉、铬、铅、钴、镓、锂等18种元素含量。比较了超级微波消解、常规微波消解和电热板消解的处理效果,采用超级微波消解法对样品进行前处理,并优化了消解条件。在最优条件下,各元素的检出限在0.05~20 mg/kg,加标回收率在86.2%~107.5%,RSD在0.1%~3.0%,方法准确度及精密度可以满足多元素同时测定的需求,且该方法具有简单、快速、成本低、用酸量少、重现性好等特点。     

基于SSFBG的±π/2和0/π相移编码的安全性比较

分别采用0/π和±π/2相移的方式对光脉冲信号进行了编码,并比较了基于超结构光纤光栅的0/π和±π/2两种相移编码方式的安全性,通过研究分析两编码器所生成的编码波形来评估各自的安全性。结果表明,0/π相移编码器生成的编码波形中存在明显的凹陷,光学码信息易被窃取,安全性低;而±π/2相移编码器生成的编码波形能隐秘地将光学码信息隐藏于编码波形中,大幅改善了编码安全性,提高了通信安全。