To extend a fiber-optic transmission system from traditional C band to C+L band, it is necessary to place Raman amplifiers to improve the optical signal-to-noise ratios (OSNR) of lightpaths. We develop a heuristic algorithm for optimal Raman amplifier placement. Simulations show that the proposed algorithm is efficient to require up to 50% fewer Raman amplifiers compared with benchmark schemes.

This paper explores the lightpath provisioning problem in a hybrid ULL fiber-SSMF elastic optical network (EON). Two routing, fiber, modulation format, and spectrum allocation (RFMSA) algorithms, namely shortest path-based and spectrum window plane (SWP)-based algorithms, are developed, along with three fiber selection strategies: random, unmixed, and adaptive strategies. Simulation results indicate that the adaptive fiber selection strategy exhibits superior advantages in improving spectrum efficiency, while the unmixed strategy excels in terms of switching node degrees and execution time.

我们报道了一种基于掺钕硅酸盐玻璃的芯径为40μm的单模多沟道光纤.在多沟道光纤的设计中同时利用了微结构光纤的离域效应和泄漏特性,采用管棒法设计并制备了硅酸盐多沟道光纤.利用10厘米长的单模多沟道光纤获得了最大输出功率～8.4瓦,斜率效率为54％的激光输出.

The coated conductors (CCs), also known as the second-generation high-temperature superconducting (2G HTS) tape, has attractive potential applications in transmissions at low magnetic field/liquid nitrogen temperatures and high-field applications at low temperatures due to their excellent critical current density and mechanical performance. Its critical current density has strong anisotropy, particularly at 77 K. Because the single tape has limited capacity of carrying current, the cable or strand making of multi-tapes, stacked in parallel, is necessary. Within recent years, several cables, such as the Roebel cable, CORC cable, TSTC cable, TS cable, and the HTS-CroCo cable, were proposed. This paper presents a status and progress on a type of HTS strand made from REBCO tapes. Its quasi-isotropic critical current is experimentally confirmed for liquid nitrogen temperature, mechanical characteristics, AC losses, thermal stability, and quench characterizations are also researched. Finally, the feasible process for the production of practical length of such strand is described by processing 10 m long sample, which is promising for applications of high fields or power transmission.

A resistive-type dc superconducting fault current limiter (SFCL) is developed for the fault current limiting at the Suzhou Nami substation. The rated voltage and current are 20 kV and 400 A, respectively. The prospective peak value of the short-circuit current is about 3.5 kA, and the current could be limited to less than 2.1 kA by the SFCL. The SFCL uses about 1800-m stainless steel reinforced yttrium barium copper oxide (YBCO) conductor. According to the testing results, the developed SFCL has passed the dc withstand voltage test at 50;kV;min, the full-wave lightning impulse voltage at 95 kV, and the dc power switching test with a peak value of 2.26 kA and a fault duration of 16.5 ms.

对应用在超导直流装置中的珀尔帖电流引线在有限元仿真软件COMSOL中建模,以最小漏热为目标对珀尔帖电流引线进行了优化设计.在确定了珀尔帖电流引线最优几何参数后,对珀尔帖电流引线在不同电流值时轴向的温度分布、漏热值、热电元件低温端温度值以及两端的温度差、热电元件两端的电势差等进行了定性分析.在最优模型的基础上,建立了考虑焊接材料时的仿真模型,分别分析了热电元件碲化铋和铜块之间焊接材料(焊锡、铟和银)对珀尔帖电流引线漏热和热电元件碲化铋低温端温度值的影响.由仿真结果分析可以得到,在热电元件碲化铋和铜块之间焊接材料(焊锡、铟和银)使珀尔帖电流引线的漏热增加了,但增量是比较小的.

The superconducting magnetic separation system (SMSS) has been gradually used in automated high capacity processing of wastewater treatment in recent years. This study investigates heavy metals (Cd, Hg, Mn, Ni, Fe, Cu and Zn) removal from aqueous solutions using a magnetic ion-exchange microsphere. Sulfonated magnetic adsorbents (PSt-SO3Na) were prepared via an aqueous suspension polymerization and a sulfonation reaction successively. The obtained adsorbents were confirmed by means of FT-IR, XRD, TEM, SEM and VSM. The adsorption capacity of PSt-SO3Na for each cation increases rapidly within first few minutes and the adsorption processes reach equilibrium in 10 min. Heavy metals removal followed pseudo-second-order kinetics, and the Langmuir adsorption isotherm model better agrees with the equilibrium data. Due to its good adsorption capacity and efficient separation by external magnetic field, PSt-SO3Na is expected to be an ideal material in the environmental application of SMSS.

High thermal conductive epoxy composites are particularly suitable for the impregnation process of superconducting power equipment due to their high electrical insulation property and low thermal expansion. In this study, the preparation and impregnation procedures of high thermal conductive epoxy (EP) composites were investigated first. Based on the orthogonal experiment results and the range analysis, the critical factors affecting on the thermal conductivity of final product in sequence were determined as aluminum nitride (AlN) filler content, filling ratio of AlN with different sizes, curing temperature, and surface modification method of AlN fillers. Through investigating the preparation factors of thermal conductive AlN/EP composites on their electrical insulation properties further, it was found that the increase of filler content, addition of nanofillers, and low curing temperature are advantageous for improving the electrical insulation property of composites. This study offers an experimental basis for the preparation and electrical application of dielectric polymer composites with high thermal conductivity in HTS equipment' manufacture.

基于超导直流电缆应用,针对第二代高温超导带材ReBCO开展了直流冲击实验.首先,通过改变冲击条件(冲击电流大小和持续时间)得到带材的耐直流冲击特性,确定可保证带材性能完好的最大冲击电流幅值(安全电流)及其相应冲击时间.随后,针对实际电缆中超导带材是以螺旋形态缠绕于支撑管上,设计实验研究超导带材螺旋角和螺旋直径对其临界电流和耐冲击特性的影响规律,发现带材所能承受的最大冲击电流幅值随冲击作用时长的增加而逐渐下降、过大的螺旋角和过小的螺旋直径均会对带材造成损伤,影响其通流能力.上述研究结果为电缆的后续设计和制造提供了必要的参考依据.

本文基于超导直流电缆应用,针对电缆中超导带材以螺旋形态缠绕于支撑管的情形,使用毕奥-萨伐定律对螺旋电流在空间任意点产生磁感应强度进行数值计算,并使用仿真软件COMSOL Multiphysics进行三维仿真.结合超导带材在外磁场下的临界电流特性,分析由此造成的电缆临界电流退化,发现在导体层带材根数相同、单根带材通流幅值相等的前提下,螺旋角度较大时磁感应强度垂直带材表面分量较小,临界电流衰减程度更小,更有利于超导电缆的稳定运行和载流能力的提升.

双极同轴结构高温超导直流电缆应用在双极直流输电系统中,其结构紧凑、工程电流密度高,可减小对外部空间的磁场影响,但对绝缘要求较高.本文依照额定电压、额定电流水平对±10 kV/6 kA双极同轴高温超导直流电缆通电导体中的绝缘层、超导导电层等主要结构进行设计,制作实物.经测试电缆满足工程要求,证明了设计的合理性.