Strengthening and toughening mechanism of a Cu-bearing high-strength low-alloy steel with refined tempered martensite/bainite (M/B) matrix and minor inter-critical ferrite

The microstructure–mechanical property relationship of a Cu-bearing low-carbon high-strength low-alloy steel, subjected to a novel multistage heat treatment inc...     

光子晶体光纤飞秒激光技术研究进展

光子晶体光纤自诞生至今的十几年来得到了快速发展,不同结构和各具特色的光子晶体光纤层出不穷。以应用于飞秒激光技术的各种光子晶体光纤为主线,介绍了目前基于光子晶体光纤飞秒激光技术的实验研究进展,尤其是高功率、高能量飞秒激光系统的研究现状和发展方向。     

Linear Study of a Large-orbit Coaxial-waveguide Cyclotron Autoresonance Maser Amplifier

A linear theory based on Maxwell-Vlasov equations and the Laplace transform is presented to describe the large-orbit coaxial-waveguide cyclotron autoresonance maser (CARM) amplifier. A 35-GHz, TE_5,1-mode large-orbit coaxial-waveguide CARM amplifier is specifically analyzed. Good agreement between the linear theory and the nonlinear simulations is found in the exponentially growing region of the wave. Results show that the operating magnetic field and the electron-beam energy and average radius substantially affect the power, and especially, a small beam current may be unsuitable to a large-orbit CARM amplifier operation.     

麦秸秆加筋盐渍土的尺寸效应与制样问题处置

制备均匀且整体性较好的试样是保证室内实验结果可靠的前提条件。提出了两端压实的静力制样法,围绕制样中出现的几个问题,制定了适宜的应对措施。同时完成了不同直径的盐渍土和麦秸秆加筋土试样的抗压强度实验,分析了试样抗压强度的尺寸效应,以及试样直径与加筋条件间的比例关系。结果显示:采用两端压实的静力制样方法制备加筋土试样是可行的;两种试样均存在明显的尺寸效应;由于麦秸秆的加筋作用,使得麦秸秆加筋土不同尺寸试样的抗压强度尺寸效应大于盐渍土的,且其抗压强度的尺寸效应随试样尺寸的增大而越来越明显;适宜加筋长度为0.316倍试样直径,适宜加筋率0.25%。研究结果可为制备合格的加筋土试样提供参考,也有益于在未来的研究中选择更合理的麦秸秆加筋条件。     

Zn‐MOF‐74 Derived N‐Doped Mesoporous Carbon as pH‐Universal Electrocatalyst for Oxygen Reduction Reaction

It is of increasing importance to explore new low‐cost and high‐activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy conversion system, including various fuel cell and metal–air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt‐based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal‐free electrocatalysts in pH‐universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen‐doped porous carbon (NPC) with high yields and exceptional quality is described. The as‐prepared NPC shows advantages of high activity, high durability, and methanol‐tolerant as an efficient pH‐universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen‐doping species and favorable pores in the as‐designed NPC synergistically contribute to the significantly improved catalytic activity in pH‐universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells.     

室温铁磁性Al2O3∶Mn的制备及性质

以Al2O3为衬底利用多能态离子注入法在离子注入设备上制备了一系列具有室温铁磁性的Al2O3:Mn样品.在Al2O3的X射线衍射峰附近发现新的衍射峰,该衍射峰既可能对应一种未知新相,也可能对应Al2O3:Mn固溶体.所有样品都具有磁滞现象和室温铁磁性.     

动作识别技术及其发展

首先简要介绍了目前主流的两个动作识别技术及其主要原理,主要包括基于图像和视频识别技术进行识别和基于运动传感器参数进行识别;然后根据这些动作识别技术重点介绍了其发展和应用状况,以及相关专利的申请状况;最后,对动作识别技术的发展前景进行展望.     

Fabrication of ZnO nanorod-based hydrogen gas nanosensor

We report a first work on nanofabrication of hydrogen nanosensor from single ZnO branched nanorods (tripod) using in-situ lift-out technique and performed in the chamber of focused ion beam (FIB) system. Self-assembled ZnO branched nanorod has been grown by a cost-effective and fast synthesis route using an aqueous solution method and rapid thermal processing. Their properties were analyzed by X-ray diffraction, scanning electron microscopy, energy dispersion X-ray spectroscopy, transmission electron microscopy, and micro-Raman spectroscopy. These analyses indicate high quality ZnO nanorods. Furthermore, our synthesis technique permits branched nanorods to be easily transferred to other substrates. This flexibility of substrate choice opens the possibility of using FIB system for handling.

The main advantage of the proposed in-situ approach is a controllable lift-out procedure which permitted us to obtain a 90% success rate for building nanodevices. The fabricated nanosensor uses only single self-assembled ZnO branched nanorod (tripod) to gauge the 150 ppm H₂ in the air at room temperature. The hydrogen sensitivity is in the range of 0.6–2% depending on which two branches to use. The nanosensor has selectivity against other gases such as O₂, CH₄, CO and LPG, which shows sensitivity of <0.02%. The single ZnO branched nanorod sensor can operate at low power of <5 μW.     

ATN路由器中路由算法IS-IS的研究与改进

路由算法和协议在路由器中的地位至关重要,文章对路由算法IS-IS及路由算法的效率进行研究和改进,提高了路由器的处理能力和稳定性。