A Hybrid Method for Multi-sensor Remote Sensing Image Registration Based on Salience Region

In order to align the remote sensing images, we propose a novel hybrid method that combines image segmentation and salient region detection, which is inspired by human vision system. First of all, we present a novel superpixel-based method for dividing the image into sub-areas. Second, we propose a novel method based on color and image textures for detecting salient regions composed by superpixels. Then, we extract a new feature based on difference of Gaussian and local binary pattern from the salient regions. Finally, the sensed image is transformed by thin-plate spline. The proposed algorithm was tested on 30 pairs of remote sensing images and compared to other three state of the art methods. Experimental results show our approach is fast and robust, while still being efficient, which is better than other three methods.     

Magnetically Modulated Pot‐Like MnFe2O4 Micromotors: Nanoparticle Assembly Fabrication and their Capability for Direct Oil Removal

This work demonstrates a simple‐structured, low‐cost magnetically modulated micromotor of MnFe₂O₄ pot‐like hollow microparticles as well as its facile, versatile, and large‐scale growing‐bubble‐templated nanoparticle (NP) assembly fabrication approach. In this approach, the hydrophobic MnFe₂O₄@oleic acid NPs in an oil droplet of chloroform and hexane assembled into a dense NP shell layer due to the hydrophobic interactions between the NP surfaces. With the encapsulated oil continuously vaporizing into high‐pressured gas bubbles, the dense MnFe₂O₄ NP shell layer then bursts, forming an asymmetric pot‐like MnFe₂O₄ micromotor by creating a single hole in it. For the as‐developed simple pot‐like MnFe₂O₄ micromotor, the catalytically generated O₂ molecules nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer convex surface, resulting in continuous ejection of O₂ bubbles from the open hole to propel it. Dexterously integrating the high catalytic activity for H₂O₂ decomposition to produce O₂ bubbles, excellent magnetic property with the instinctive surface hydrophobicity, the MnFe₂O₄ pot‐like micromotor not only can autonomously move in water media with both velocity and direction modulated by external magnetic field but also can directly serve for environmental oil removal without any further surface modification. The results here may inspire novel practical micromotors.     

Electrochemical and Top‐Down 3D Ion‐Carving to Change Magnetic Properties

It is challenging to develop new top‐down approaches to tailor particles into subnanometer size structures on a large scale to further reveal their structure‐dependent physicochemical properties. Here, we demonstrate a non‐conventional, electrochemical, 3D ion‐carving process to tailor particles into subscale flower‐like nanostructures at room temperature. The technology is based on the electrochemical insertion/extraction of lithium ions as a carving “knife” to carve the single‐crystalline particle precursor into higher‐order, flower‐like nanostructures with hexagonal nanopetals as the building units. Our study demonstrates that the morphology of the as‐carved, flower‐like nanostructures can be controlled by the electrochemical parameters, such as the current density and the number of cycles. Particularly interesting is that dramatically different magnetic properties can be achieved depending on the morphology through careful tuning by the electrochemical ion‐carving process. The as‐carved, flower‐like particles may find many important applications, including magnetic nanodevices. Our approach, in principle, is applicable to prepare various kinds of 3D‐structured materials with different compositions.     

建设高效的网络播出灾备系统

随着计算机系统越来越多的使用,系统的复杂度与关键性也与日俱增.企业灾备方案也越来越多地提上议事日程.如何建立灾备体系?到底如何选择适合的灾备技术路线?本文将从灾备的目标与要求出发,注重灾备方案的经济性与有效性,对常用的几种灾备方式的比较,通过实际的案例,抛砖引玉,帮助对灾备方案进行正确的理解与决策.     

基于LDDMA的多用户分集性能分析

针对线性离散多址复用（LDDMA）系统,文章研究在线性迫零（Zero-Force）接收机条件下的多用户选择分集与调度算法。对于用户子集选择算法,遍历搜索是最优的,但它所引起的繁重的计算复杂度,很难在实际中应用。基于此考虑,本文提出三种次优的贪婪选择准则：最大信道增益选择,最大信道容量选择与最大最小后验SNR选择。数值仿真结果表明：最大最小后验SNR准则可以提供较好的BER性能。     

防辐射服屏蔽效能研究与测试(上)

随着电子工业的迅猛发展和通信技术的不断进步,各种无线电该禾已经被广泛应用于人们日常生产生活的各个方面,把人们带进了一个充满电磁辐射的环境里,对人体健康产生一定的影响,穿着舫辐射服是一种简单而有效的防护方法.该文从防辐射服的作用原理、不同产品的实际屏蔽效能等方面进行研究和测试.根据实际侧试数据给消费者和行业监管提供一定的...     

HEMT器件小信号模型研究

提出一种AlGaAs/GaAs HEMT器件沟道电荷新模型,该模型用一个通用解析函数中系数的不同值来描述二维电子气(2DEG)和AlGaAs层中的电子浓度。在小信号特性上,除考虑了2DEG层外,又在考虑了AlGaAs层、速度饱和、饱和区沟道长度调制效应和源、漏串联电阻RS和RD等效应的基础上,推导出直流特性、跨导、输出电导和栅电容的解析表达式。仿真说明,在较大的栅、漏压范围内,该模型的理论值与实验结果符合良好。     

多晶硅薄膜晶体管RPI模型的直流参数提取

多晶硅薄膜晶体管(TFT)在有源液晶显示器中的应用充分显示了它的性能优点。对多晶硅TFT进行模型分析和参数提取是理解多晶硅TFT工作原理和指导制备的有效途径。归纳并讨论了多晶硅薄膜晶体管RPI模型直流参数的提取策略。此参数提取步骤简单,并能准确地提取所有工作区的基本直流参数,如阈值电压、漏源区串联寄生电阻、有效沟道长度、迁移率等。参数提取的方法将为RPI模型的电路仿真提供有益的参考。最后,提出了改进RPI模型参数提取策略的方向,包括提高泄漏电流参数、迁移率参数的准确度等。     

大型环境试验舱研制与应用

研制一种大型不锈钢环境试验舱,对舱的性能进行测试,结果发现：温湿度控制精密,气密性好,本底污染物浓度低,回收率高,自衰减率低,能真实模拟室内环境,完全满足检测和科研要求。使用该环境试验舱分别测试了空气净化器和散热器,发现该舱性能完全符合检测需要,测试结果符合实际运行情况。     

Concise stereoselective synthesis of marine sesterterpene, 16-deacetoxy-12-epi-scalarafuran acetate and its 14-epimer via intramolecular Diels-Alder addition

The stereoselective synthesis of C12 oxygenated marine scalaranic sesterterpene 16-deacetoxy-12-epi-scalarafuran acetate and its 14-epimer were described. A highly stereoselective intramolecular Diels-Alder addition was designed as the key step to construct the ring D, and the absolute configurations of natural 16-deacetoxy-12-epi-scalarafuran acetate was supported by the X-ray diffraction analysis of single crystal of corresponding 16-deacetoxy-12-epi-scalarafuran.