基于PLC的紧凑型回旋加速器联锁保护系统

介绍了CYCHU10紧凑型回旋加速器联锁保护系统的实现方法.系统选取以PLC为核心,现场总线为网络构架,S7Graph为主要编程语言的技术路线,采用分布式结构和结构化程序设计方法,从硬件和软件上保证了联锁保护系统的可靠性、可维护性及可扩充性.应用结果表明,该联锁系统较好地整合了加速器各子系统,为加速器的安全稳定运行提供了保障,取得了理想的控制效果.     

印刷专业教师研讨会在河内举行

德国印刷促进会在国外为专业教师举办的第二次研讨会,于3月23日至25日在越南河内印刷工业学院(Hanoi college of printing industry)成功举办。出席研讨会的约50名专业教师,来自印尼和越南的10所不同的大学和培训中心。     

WIPO Panels’ interpretation of the Uniform Dispute Resolution Policy (UDRP) three-prong test

The Uniform Dispute Resolution Policy (UDRP) is a unique process that resolves domain name disputes effectively and inexpensively. This paper, through an analysis of the UDRP three-prong test, revealed that even though the UDRP affords a great degree of discretion to the WIPO Panels deciding any given case, there is some consistency and predictability inherent in the UDRP process.     

Theoretical Analysis of Diffraction Efficiency of Photocarrier Grating

The diffraction efficiency of the photocarrier grating (PCG) has been theoretically analyzed. Firstly, the model of the PCG has been set up, and the distribution of the carrier concentration has been studied. Secondly, the change in refractive index produced by the photocarriers has been estimated. Finally, a rigorous coupled-wave analysis has been employed to investigate the diffraction efficiency of the PCG. The results show that when the angle between the two excitation lasers increases, the change of the refractive index decreases, leading to a weak grating. The optimal incident angle of the probe laser is dependent on the angle between the two excitation lasers, and the relation between these two angles for the higher diffraction efficiency of the +1st forward-diffracted wave has been found. In terms of diffraction efficiency, the optimal parameters have been estimated, and the feasibility of the PCG to be a forward-diffracted component has been confirmed.     

对资金时间价值的再认识

在对资金时间价值的内涵进行分析的基础上,文章提出了资金时间价值应用中需要注意的一些事项。这对更好地运用时间价值的观念去解决实际问题具有参考价值。     

大规模风电接入电网及市场消纳问题分析

目前风电外送与接入是电网企业与风电开发企业矛盾比较集中的焦点问题.我国风电场主要分布在距负荷中心较远的地区,电网结构相对薄弱,电网建设对风电开发存在一定的制约.在我国西北、华北以及东北(尤其是内蒙古东部地区)风电基地集中地区,风电发出的电力无法正常并网,已经成为未来风电发展所面临的最大问题.针对这一难题,以电网运行管理者的视角,从风电侧和电网侧两个方面,对风电并网问题进行了深入研究,找出其中的难点,并作进一步分析.在国外相关实际做法的基础上,对发电侧、负荷侧以及并网风电管理等方面,提出了提高发电机组调峰能力、适当建设快速调节机组、实施峰谷电价等旨在促进我国风电健康有序发展的实用化建议.     

Multi‐Atomic Layers of Metallic Aluminum for Ultralong Life Lithium Storage with High Volumetric Capacity

Metallic aluminum (Al) have been explored as potential anode materials for lithium storage because of its high theoretical capacity (993 mAh g^–1) and low voltage plateaus. Al possesses high electric conductivity, low cost and environmental friendliness. Unfortunately, Al suffers from huge volume change (>100%) during the lithiation/delithiation process, which inevitably results in the pulverization of electrode and rapid capacity decay during cycling processes. To circumvent above issues, a simple but efficient strategy is demonstrated to fabricate free‐standing multi‐atomic layers of metallic Al by harnessing the good ductility of Al under pressure. The resultant multi‐atomic Al layers are ultrathin, ≈3 nm, and have a large aspect ratio. Such unique features enable multi‐atomic Al nanosheets to construct uniform and compact films with graphene. Thus, the hybrid films with different ratios are achieved, in which the notorious volume change of metallic Al can be efficiently circumvented via the good flexibility of graphene, and the density of whole electrode can be significantly enhanced. As a consequence, the optimized multi‐atomic Al layers‐graphene (AlL‐G) film exhibits a very high volumetric capacity of 1089 mAh cm^–3, high‐rate capability and ultralong cycle life up to 20 000 cycles for lithium storage.     

Synchronous Growth of High‐Quality Bilayer Bernal Graphene: From Hexagonal Single‐Crystal Domains to Wafer‐Scale Homogeneous Films

The precise control of the domain structure, layer thickness, and stacking order of graphene has attracted intense interest because of its great potential for nanoelectronics applications. Much effort has been devoted to synthesize semiconducting Bernal (AB)‐stacked bilayer graphene because of its tunable band structure and electronic properties that are unavailable to single‐layer graphene. However, fast growth of large‐scale bilayer graphene sheets with a high AB‐stacking ratio and high mobility on copper poses a tremendous challenge, which has to overcome the self‐limiting effect. This study reports a low‐cost but facile method to rapidly synthesize bilayer Bernal graphene by atmospheric pressure chemical vapor deposition using polystyrene as the feedstock. The bilayer graphene grains and continuous film obtained are of high quality and exhibit field‐effect hole mobilities as high as 5700 and 2200 cm² V^?1 s^?1 at room temperature, respectively. In addition, a synchronous growth mechanism of bilayer graphene is revealed by monitoring the growth process, resulting in a high surface coverage of nearly 100% for a near‐perfect AB‐stacking order. This new synthesis route is significant for industrial application of bilayer graphene and investigation of the growth mechanism of graphene by the chemical vapor deposition process.     

S波段GaAs高效率线性内匹配HFET研制

介绍了一种基于GaAs HFET结构的S波段内匹配器件的设计方法。由于大栅宽器件模型难以准确确定,提取了具有相似结构的小栅宽器件模型。在ADS设计环境中,利用Load-Pull算法推算出大栅宽器件的管芯阻抗。器件采用两个栅宽为16mm的管芯进行功率合成。对于匹配电路的设计,首先通过一级LC低通滤波网络进行阻抗变换,将每个管芯的阻抗提升到10Ω左右,再通过Wilkinson功分器将阻抗变换到50Ω。电容和功分器采用瓷片加工,电感则通过金丝实现。研制成功的内匹配功率管,其工作频率为2.2～2.5GHz,输出功率P1dB大于20W,功率增益G1dB大于14dB,功率附加效率大于48%。     

卫星通信地球站建设工程监理要点分析

卫星地球站是卫星通信系统的重要组成部分,其工程质量对系统的功能实现和性能指标将产生重大影响。卫星通信地球站建设中引入工程监理制度是保证工程质量、达到设计目标的有力举措。文章首先介绍了地球站建设的阶段划分,其次结合卫星通信理论和实际工程经验对卫星地球站工程监理中各阶段把控要点进行梳理、归纳,最后总结全文。