Grammatical evolution in developing optimal inventory policies for serial and distribution supply chains

Recently, there has been a growing literature on biologically inspired algorithms, particularly genetic algorithms and genetic programming, applied to supply chain modelling and inventory control optimisation. Due to the rigidity of the genetic algorithms approach, it is difficult to change the underlying model logic and add richness to the supply chain. While genetic programming provides a more flexible approach than that provided by genetic algorithms, to date its application has been limited to small supply chain modelling problems in relation to optimal inventory policies. This research applies Grammatical Evolution, a relatively new biologically inspired algorithm, to the field of supply chain optimisation, employing human readable rules called grammars. These grammars provide a single mechanism to describe a variety of complex structures and can incorporate the domain knowledge of the practitioner to bias the algorithm towards regions of the search space containing better solutions. Results are presented showing Grammatical Evolution is at least competitive in cost terms, and superior in flexibility, with these methods applicable to any supply chain of the serial or distribution type. Furthermore, Grammatical Evolution shows an adaptive ability that augurs well for supply chains in dynamic environments, such as disruption.     

Smart Utilization of Carbon Dots in Semiconductor Photocatalysis

Efficient capture of solar energy will be critical to meeting the energy needs of the future. Semiconductor photocatalysis is expected to make an important contribution in this regard, delivering both energy carriers (especially H₂) and valuable chemical feedstocks under direct sunlight. Over the past few years, carbon dots (CDs) have emerged as a promising new class of metal‐free photocatalyst, displaying semiconductor‐like photoelectric properties and showing excellent performance in a wide variety of photoelectrochemical and photocatalytic applications owing to their ease of synthesis, unique structure, adjustable composition, ease of surface functionalization, outstanding electron‐transfer efficiency and tunable light‐harvesting range (from deep UV to the near‐infrared). Here, recent advances in the rational design of CDs‐based photocatalysts are highlighted and their applications in photocatalytic environmental remediation, water splitting into hydrogen, CO₂ reduction, and organic synthesis are discussed.     

形态演变对家电产品风格的影响研究

目的探讨冰箱形态演变的影响因素并研究形态演变对家电产品风格的影响。方法搜集了海尔冰箱的相关产品资料,提取了冰箱主面板形态特征并进行数据统计分析,对不同型号冰箱的线条特征、分割比例等造型元素进行了归纳总结。结论冰箱的形态演变主要受消费者需求变化和设计风格的影响。     

钛基亚氧化钛电极电化学降解性能研究

采用SEM、EDS对钛基亚氧化钛电极进行形貌和成分表征,用线性极化曲线法和循环伏安法测试电化学性能,通过降解模拟污水测试降解性能以及用荧光光谱法检测自由基。结果表明,钛基亚氧化钛电极上不能发生直接氧化反应,但是电极析氧电位可达2.18 V(vs.SCE),并且检测到生成大量·OH,是一种类似于Ti/SnO_2的惰性电极,在Na Cl和Na2SO4电解质溶液中电流效率分别达40.95%和22.52%,降解效果优于Ti/SnO_2和Ti/Ru Ir电极。     

A simple spatial integration scheme for solving Cauchy problems of non-linear evolution equations

In this study, we address a new and simple non-iterative method to solve Cauchy problems of non-linear evolution equations without initial data. To start with, these ill-posed problems are analysed by utilizing a semi-discretization numerical scheme. Then, the resulting ordinary differential equations at the discretized times are numerically integrated towards the spatial direction by the group-preserving scheme (GPS). After that, we apply a two-stage GPS to integrate the semi-discretized equations. We reveal that the accuracy and stability of the new approach is very good from several numerical experiments even under a large random noisy effect and a very large time span.     

基于离散元方法的沥青混合料力链演化及分布量化分析

为了研究沥青混合料内部颗粒间力链的演化及分布规律,以AC-13沥青混合料作为研究对象,利用离散元方法重构沥青混合料数字试件,模拟简单性能试验,提取试件内部颗粒间的力链信息进行力链演化、概率分布和角度分布分析。结果表明,通过比较预测结果和实测结果,基于离散元方法重构的AC-13沥青混合料细观模型用于模拟其细观力学特性是可行的。试件内部力链空间分布具有各向异性,以垂直方向的压力力链为主,承受大部分的半正弦荷载。法向力链概率分布随加载时间的变化规律基本一致,法向接触力与平均法向接触力比值f最小时,概率分布出现最大值,f=1.75时,概率分布再次达到峰值,然后逐渐减小并趋于稳定。法向力链角度分布主要位于90°和270°附近,第一、二象限的角度分布比例远大于第三、四象限,60~120°、30~150°中法向力链角度分布比例均大于70%,最小为72.733%。     

Effects of T5 heat treatment on extrusion welds in AZ80 hollow profile

AZ80 hollow profile was produced by porthole-die extrusion. The mechanical behavior and microstructure characteristic of extrusion welds in AZ80 hollow profile during different T5 heat treatments were investigated. Five kinds of morphologies of β-Mg₁₇Al₁₂ were observed in turn in weld regions under various temperatures. Extrusion weld is not weakest region in AZ80 hollow profile in terms of hardness, the peak hardness of weld regions is roughly equal to the weld-free regions at different aging temperatures, which is attributed to similar volume fraction, morphology, and size of β-Mg₁₇Al₁₂ precipitate in weld regions and weld-free regions. The precipitate-free zones (PFZs) usually form near the welds interface in aging process, and the hardness of PFZs is usually lower than those of weld regions and weld-free regions. Aging at 200°C for 24?h is suitable heat treatment system for AZ80 hollow profile, which can achieve excellent mechanical property and simultaneously reduce the width of PFZs.     

航天器振动试验控制技术进展

航天器对恶劣动力学环境的适应能力直接关系到整个航天飞行任务的成败,振动试验控制技术是动力学环境试验的关键环节.本文分析了近年来国内外航天器振动试验设备和振动控制算法的研发动态、基本原理和关键技术达到的水平.提出了跟踪研究的基本思路,途径及建议.     

我国青年现阶段价值观演变状况与导向

在市场经济的冲击下,我国青年现阶段的价值观发生了很大的变化,主要表现为:一元化价值观向多元化价值观演变;理想主义价值取向转为务实求实的价值取向;群体本位向个体本位取向偏移。在这个价值观转变当中,往往出现一些畸形的价值取向,所以应坚持正确的导向,强化新的价值观。     

基于差分进化算法的智能组卷方法

如何从庞大试题库中自动生成符合教学和考试要求的一套试卷是目前我国利用计算机进行辅助教学的一个重要研究内容.通过分析用户对组卷的要求和试题结构特征.构建了一个智能优化组卷新模型,同时给出了求解的差分进化算法.数值试验结果表明,所给的方法在组卷效率和质量方面具有更好的性能.