“Optimization of aircraft maintenance/support infrastructure using genetic algorithms—level of repair analysis”

Level of repair analysis (LORA) is an approach used during the design stage of complex equipment for analysis of the cost effectiveness of competing maintenance strategies. LORA is carried as a part of the life cycle cost and cost of ownership analysis and plays a significant role in minimizing the life cycle cost and cost of ownership of the capital equipment. Since many purchasing decisions of complex equipment are based on cost of ownership, it has become essential to carry out LORA to compete in the market. In this paper, we develop a mathematical model for LORA and propose a solution methodology based on genetic algorithms. The concept is illustrated using a hypothetical aircraft engine.     

生鲜供应链中保鲜努力投入及订货定价研究

结合生鲜损耗严重和过度保鲜双重背景,本文在区分保质期和实际有效供货时长的基础上,比较研究了由单一零售商与单一供应商构成的二级生鲜供应链中,两个主体合作与否及主导主体变化对供应链保鲜努力水平和定价的影响机制。研究表明,集中式供应链中,保鲜努力投入随新鲜度(价格)敏感性增强(减弱)而增加,而随有效供货时长增加呈倒U型;供应链的总利润也随新鲜度(价格)敏感性增强(减弱)或有效供货时长上升而增加。分散式供应链中,随新鲜度的敏感性增强,保鲜努力和总利润增加;随价格的敏感性增强,保鲜努力增加而总利润减小;而随有效供货时长上升,保鲜努力先增大后减小,总利润增加。分散式供应链存有搭便车的机会,但因有效供货时长占保质期比例不同,自身投入保鲜努力可能比搭便车更有利。     

关于矩阵的行最简形以及两个正交矩阵之和的几个注记

本文证明了每个ｍ×ｎ矩阵Ａ的行最简形矩阵必唯一．本文还给出了两个正交矩阵之和仍是正交矩阵的两个充分必要条件．     

Fabrication and Performance of 1.55 μ/m Transmission Glass-Echelon Grating Filters

This paper describes the fabrication method and the measured spectral behavior of a 1.55 μm transmission glass-echelon grating filter. This echelon grating consists of a pile of identical plane-parallel glass plates constructed using a special assembling tool. The experimental result confirmed the accuracy of the Fourier transform which indicated that the spectral passband width was inversely proportional to the beam size. This feature makes it possible to use the filter as a bandpass filter or a comb filter when constructing photonic networks. The echelon filter has certain intrinsic advantages including a low insertion loss and polarization independence. Moreover, it offers good cost performance and excellent design flexibility.     

Spectral Analysis of Transmission Echelon Grating Filters for Photonic Networks

This paper describes a method of analyzing spectral behavior that allows transmission echelon grating filters to be designed for use in constructing photonic networks. These networks include dense wavelength division multiplexing systems and other such applications. First, the configuration and principle of this filter are described. Then, the transmittance spectrum of the transmission echelon grating filter is considered for incident lights with rectangular, Gaussian, and sinc electric field distributions. Next, a more realistic spectral response is considered by taking reasonable fabrication errors into account. Finally, the group delay and the transmittance of linearly chirped echelon grating filters are analyzed to access their potential for use as a wavelength dispersion equalizer. These analytical results make it possible to design practical echelon grating filters.     

液晶散射法产生部分相干光实验

 对无阶梯诱导空间非相干技术中前级光源太弱的问题进行了分析,开展了前级部分相干源的研究工作。利用向列液晶的电光特性,选用两种液晶盒作为散射体,完成了液晶散射法产生部分相干源的原理性实验,得出液晶散射光能量透过率、均匀性及相干性与外加电场的关系。实验表明通过改变外加电场,可以提高液晶散射光的强度和均匀性,同时降低其空间相干性。     

迈克耳孙对光学精密仪器及光谱学的研究

扼要回顾了迈克耳孙的生平，介绍了他用干涉仪测定标准来尺和研究光谱线的精细结构等方面的工作；以及他发明阶梯光栅、制造光栅刻划机和星体干涉仪等仪器所取得的重大功绩，强调了他在创新中不怕困难，敢于标新立异的精神。     

用组合方法证明Gaussian系数恒等式

设F_q是q个元素的有限域,其中q是素数的幂,F_q~n是F_q上n维向量空间,用[n/m]_q表示Gaussian系数,它可看作为F_q~n的m维子空间的个数.用组合方法证明了几个Gaussian系数恒等式.     

退役磷酸铁锂电池的梯次利用和正极材料回收方法现状

随着纯电动汽车的飞速发展,锂离子电池(LIBs)的消耗量日渐增大。磷酸铁锂电池(LFPBs)因安全性能优越、使用寿命长、原材料价格低廉、环境友好且技术成熟等优势,在市场上存量较大。因此退役磷酸铁锂电池报废量也逐年增加,对于其回收方法的研究迫在眉睫。基于此,文章总结了当前锂电池的梯次利用现状,包括退役磷酸铁锂电池性能测定的多种方法,不同余能适用的场合以及投资回报分析。并对磷酸铁锂电池中金属的回收工艺进行了对比,包括破碎、风选、涡电流、冷激等物理方法,浸出、沉淀、活化等化学方法以及生物浸出方法。介绍了修复再生磷酸铁锂(LFP)的相关技术,以期实现退役磷酸铁锂电池资源利用最大化,并为后续有关回收退役磷酸铁锂电池的研究提供技术参考。     

Amenable Köthe co‐echelon algebras

In this note we investigate amenability properties in the class of the so‐called DF‐algebras. We also characterize, in terms of the defining sequence of weights, amenable Köthe co‐echelon algebras.