多芯光纤熔接与测试研究

多芯光纤(MCF)是空分复用(SDM)技术的重要传输介质,能够数倍地拓展现有单根光纤的通信容量,然而MCF结构复杂度高、测试难度大,尚无测试标准。文章根据MCF的结构特点,结合在MCF开发中的技术经验,规范了MCF的熔接方法以及主要参数的测试方法,为未来MCF的大规模商用化奠定了基础。     

一种运用SVM分类的多源态势数据关联方法

阐述如何利用多手段获取的战场多源目标态势数据生成战场态势一张图,进一步提高海上方向的监控能力。针对多源目标态势数据存在的时空误差、属性模糊等问题,提出一种运用支持向量机(Support Vector Machine,SVM)分类的多源态势数据关联方法。运用机器训练学习方式,获取不同误差下的多源态势关联,识别非线性特征参数,构建多源态势数据关联算法模型,有效形成目标批号和时空位置的唯一性。通过模拟真实数据进行验证,结果表明该算法实现效果较好,在多源态势融合方面具有较好的实用价值。     

涂敷硬涂层的整体叶盘有限元建模与减振性能分析

为了在整体叶盘结构上有效实施硬涂层阻尼减振技术,以简化整体叶盘为对象并基于Mindlin板理论,建立叶片双面涂敷Ni Cr Al Co Y+YSZ硬涂层硬涂层整体叶盘的有限元模型,并给出求解涂层整体叶盘固有特性和在阶次激励作用下的频域振动响应的方法。然后,用实验验证所建的有限元模型的正确性,并着重分析涂层厚度对整体叶盘减振效果的影响。研究表明:涂敷硬涂层后,整体叶盘的各阶模态阻尼比显著增大,阶次激励作用下的共振响应明显减小。     

Cu_x[Ni_3Fe_1](x=4～12)合金的组织演变北大核心CSCD

研究了Cu-Ni-Fe系列合金中组织结构演变及其对性能的影响。本文固定Ni∶Fe原子比为3∶1,连续改变Cu含量,设计制备了Cu_x[Ni_3Fe_1](x=4,7,9,12)系列合金,并利用光学显微镜、扫描电子显微镜、X射线衍射仪、维氏硬度计、万能试验机、变温电阻仪对合金的表面形貌、物相结构、硬度、拉伸性能及电阻率进行了分析。结果表明:Cu_x[Ni_3Fe_1]合金中主要的强化方式是调幅分解;随着Cu含量的增加,调幅分解形成的富Ni-Fe逐渐减少,合金的抗拉强度、屈服强度以及硬度都呈减小的趋势;编织板条状的组织因排列密度高,表现出良好的耐蚀性;x为4、7和9的合金时效后有少量的γ'-Ni_3Fe析出相,对合金的硬度和拉伸性能影响不大,但γ'-Ni3Fe相在500℃左右会发生分解,导致电阻率略有下降;而x为12的合金时效后晶界上有大量α-Fe相析出。     

NiFe-植酸复合物的室温制备及其全解水电催化性能

制备高稳定性、高活性双功能催化剂用于全解水制氢是氢能源大规模商业化应用的重要环节之一。本文以植酸(PA)、六水合氯化铁(FeCl₃·6H₂O)和六水合氯化镍(NiCl₂·6H₂O)为原料,采用两步室温浸渍法在泡沫镍(NF)上制备了片状无定形植酸-镍铁双金属复合材料(NiFe-PA)。采用线性扫描伏安法(LSV)考察了NiFe-PA修饰NF电极(NiFe-PA/NF)在碱性条件(1.0 mol/L KOH)的电解水催化性能。实验结果表明：由于NiFe双金属之间的协同效应,NiFe-PA/NF作为双功能催化剂显示出优越的析氧和析氢性能。NiFe-PA/NF电极在50 mA·cm^-2电流密度下析氧反应的过电位仅需220 mV;在10 mA·cm^-2电流密度下的析氢反应的过电位为135 mV。将NiFe-PA/NF组装成双电极系统用于全解水,达到10 mA·cm^-2电流密度的电池电压仅需1.61 V,低于贵金属催化剂体系RuO₂     

Effect of post-slaughter processing and freezing on the functionality of hot-boned meat from young bull

The effects of variation in the times of mincing post mortem (2, 4, or 6 h), pre-rigor salting (1.5% wt wt ) and freezing rate [fast (10 min, liquid nitrogen); medium (4-6 h at -40 °C and 0.8 m s(-1) air velocity); or slow (36-38 h at -10 °C and 0.1 m s(-1) air velocity followed by 12 h at -20 °C and 0.1 m s(-1) air velocity)] on the functionality of young bull meat were examined using hot-boned forequarters. At 52 h post packaging, the meat was thawed (72 h at 4 °C), its pH measured, and it was used to make finely comminuted batters. Cook yield and stress and strain of the cooked batters were measured. Time of mincing had no effect on meat pH, cook yield or stress and strain. There was a significant interaction (P < 0.05) between pre-rigor salting and freezing rate for pH. Freezing rate did not affect the pH of pre-rigor salted meat whereas the pH of unsalted pre-rigor meat was highest at the fastest freezing rate. Meat salted pre-rigor had a significantly (P < 0.05) higher pH than the post-rigor chilled control. Pre-rigor salting decreased the stress values of cooked batter whereas the slowest freezing rate increased stress. Stress and strain values for cooked batters from thawed meat were not significantly different from the values for batters made from the unfrozen control. Cook yields of batters made from pre-rigor frozen meat were higher than that of the postrigor control but not significantly so. The results indicate that suppliers can use pre-rigor salted and frozen meat when manufacturing comminuted products without major detrimental effects on the cook yield and texture of the finished product.     

National Institute of Standards and Technology high-accuracy cryogenic radiometer

A high-accuracy cryogenic radiometer has been developed at the National Institute of Standards and Technology to serve as a primary standard for optical power measurements. This instrument is an electrical-substitution radiometer that can be operated at cryogenic temperatures to achieve a relative standard uncertainty of 0.021% at an optical power level of 0.8 mW. The construction and operation of the high-accuracy cryogenic radiometer and the uncertainties in optical power measurements are detailed.     

Photonic page buffer based on GaAs multiple-quantum-well modulators bonded directly over active silicon complementary-metal-oxide-semiconductor (CMOS) circuits

We present a 2-kbit, 50-Mpage/s, photonic first-in, first-out page buffer based on gallium arsenide/aluminium-gallium arsenide multiple-quantum-well diodes that are flip-chip bonded to submicrometer silicon complementary-metal-oxide-semiconductor circuits. This photonic chip provides nonvolatile storage (buffering), asynchronous-to-synchronous conversion, bandwidth smoothing, tolerance to jitter or skew, spatial format conversion, wavelength conversion, and independent flow control for the input and the output channels. It serves as an interface chip for parallel-accessed optical bit-plane data. It represents the first smart-pixel array that accomplishes the vertical integration of multiple-quantum-well modulators and detectors directly over active silicon VLSI circuits and provides over 340 transistors per optical input-output. Results from high-speed single-channel testing and real-time array operation of the photonic page buffer are reported.     

二次型单神经元自适应算法在电动机控制中的应用

针对直流电动机调速系统现有控制方法存在PID控制器参数固定而导致控制效果差的问题,提出了二次型单神经元自适应PID控制算法,即在加权系数的调整中引入二次型性能指标,通过计算控制律可以得到所期望的优化效果。Matlab仿真结果表明,该算法可改善控制系统的动态过程品质,降低超调量,缩短稳定时间,并且有一定的抗干扰能力。