NLOS Identification for Localization Based on the Application of UWB

Wireless Personal Communications - Ultra-wide bandwidth (UWB) transmission is a promising technology for localization systems, due to its power efficiency, strong penetrability, and robust...     

5G技术的趋势与发展关键

5G技术是4G后的下一代通信技术,目前处于探索阶段,具有广阔的应用空间。根据国内外技术发展的新趋势、新动态,对5G技术的未来发展进行分析,阐述其关键技术,同时介绍国内最新的发展情况。     

Electrochemical performance of arc-produced carbon nanotubes as anode material for lithium-ion batteries

The effects of etching process on the morphology, structure and electrochemical performance of arc-produced multiwalled carbon nanotubes (CNTs) as anode material for lithium-ion batteries were systematically investigated by TEM and a variety of electrochemical testing techniques. It was found that the etched CNTs exhibited four times higher reversible capacity than that of raw CNTs, and possessed excellent cyclability with almost 100% capacity retention after 30 cycles. The kinetic properties of three kinds of CNTs electrodes involving the pristine (CNTs-1), etched (CNTs-2) as well as etch-carbonized samples (CNTs-3) were characterized via ac impedance measurement. It was indicated that, after 30 cycles the exchange current density i₀ of etched CNTs ((7.6-7.8) × 10⁻³ A cm⁻²) was higher than that of the raw CNTs (5.9 × 10⁻³ A cm⁻²), suggesting the electrochemical activity of CNTs was enhanced by the etching treatment. The storage characteristics of the CNTs electrodes at room temperature and 50 °C were particularly compared. It was found that the film resistance on CNTs electrode generally tended to become large with the elongation of storage time, especially storage at high temperature. In comparison with CNTs-1 and CNTs-3, CNTs-2 exhibited more distinctly increase of film resistance, which is related with the surface properties.     

Energy-efficient switching scheme for SAR ADC with only two reference voltages

An energy-efficient switching method for successive approximation register analog to digital converter is presented in this letter.The proposed two-step switching scheme using the goblet architecture achieves 99.52% less switching energy and 21.09% area reduction over the conventional switching scheme. Moreover, owing to the application of the goblet architecture, the proposed scheme employs only two reference voltages without any requirements for stability or accuracy of the third voltage level.     

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.     

大跨度钢结构承重楼盖阻尼减震技术

奥林匹克国家会议中心大宴会厅L4桁架跨度大,人正常行走、跳跃时容易产生共振,中间跨中的加速度超过人体舒适度的要求,经计算、分析确定采用TMD粘滞流体阻尼器的减振方案。试验表明TMD-粘滞流体阻尼器的减振效果非常明显,为今后类似工程积累了宝贵的经验和试验数据。     

液化天然气气化站的预冷技术

介绍了国内LNG的应用状况、液化天然气的特性、液化天然气气化站的工艺,论述了气化站投产预冷的必要性和目的,介绍了预冷前管道吹扫、预冷过程及预冷检查内容。     

亚硫酸盐浆CEH漂白废水的特性及其光催化氧化处理

本文对蔗渣、竹子、芒杆混合亚硫酸盐浆ＣＥＨ 漂白废水的特性进行了较详细的分析研究。研究表明,该废水ＢＯＤ５／ＣＯＤ为０ ．１８３ ,Ｃｌ－ 含量高达１１５２ ．５ｍｇ／ｌ,不适合于传统的生物氧化法处理。废水中的大分子有机污染物是废水色度的主要来源,废水的色度和ｐＨ 值密切相关。采用ＵＶ／ＴｉＯ２ 光催化氧化工艺处理该废水的初步研究结果表明,在充分供氧的条件下,可使废水快速脱色,同时废水的ＣＯＤ指标大大下降。     

生活用纸湿强剂PAE残留的风险评估

介绍了生活用纸中湿强剂聚酰胺环氧氯丙烷树脂（PAE）的残留状况及对人类健康的风险隐患;结合欧盟法规规定和风险评估模型,计算了生活用纸中残留PAE经皮肤摄入的风险指数,并进行了PAE残留风险评估。结果表明,PAE中的有机氯代物在纸巾纸等生活用纸中残留的概率较大,长期接触这些有害物质将对使用者的身体健康产生潜在的风险隐患。     

某200MW机组动、静叶片损坏事故原因探讨

从国产某２００ＭＷ 汽轮机中压动、静叶片损坏的事故入手,通过从设计、维修、运行和事故现场情况的分析,认为事故的原因是维修不当造成,并提出避免的建议