设施园艺在观光农业园规划设计的应用

设施园艺可以让农业生产者通过一定的技术手段,提高农业生产效益,改变农作物的生长周期。文章在农业观光园的设计中可以利用这种技术方法来突出园区的农业特色,吸引非农业人口前来旅游观光和消费。     

单相并联型有源电力滤波器主电路参数耦合关系研究

单相并联型有源电力滤波器(SAPF)主电路参数之间存在一定的耦合关系,这对各参数值的合理选择有较大的影响。通过分析现有单/三相SAPF主电路交流侧电感以及直流侧电压、电容值等参数的计算方法,得到了具体的单相SAPF电路参数解析表达式。针对所得表达式各变量之间的耦合关系,在MATLAB中进行建模优化分析,得出一套完整的参数设计方案。保证在特定负载下补偿后谐波含量低于2%的综合优化目标。仿真和实验过程验证了所选参数的正确性。     

Structural and Functional Characterization of 4-Hydroxyphenylacetate 3-Hydroxylase from Escherichia coli

The hydroxylation of phenols into polyphenols, which are valuable chemicals and pharmaceutical products, is a challenging reaction. The search for green synthetic processes has led to considering microorganisms and pure hydroxylases as catalysts for phenol hydroxylation. Herein, we report the structural and functional characterization of the flavin adenine dinucleotide (FAD)-dependent 4-hydroxyphenylacetate 3-monooxygenase from Escherichia coli, named HpaB. It is shown that this enzyme enjoys a relatively broad substrate specificity, which allows the conversion of a number of non-natural phenolic compounds, such as tyrosol, hydroxymandelic acid, coumaric acid, hydroxybenzoic acid and its methyl ester, and phenol, into the corresponding catechols. The reaction can be performed by using a simple chemical assay based on formate as the electron donor and the organometallic complex [Rh(bpy)Cp*(H₂O)]²⁺ (Cp*: 1,2,3,4,5-pentamethylcyclopentadiene, bpy: 2,2′-bipyridyl) as the catalyst for FAD reduction. The availability of a crystal structure of HpaB in complex with FAD at 1.8 Å resolution opens up the possibility of the rational tuning of the substrate specificity and activity of this interesting class of phenol hydroxylases.     

[学科发展]机构学中机构重构的理论难点与研究进展——变胞机构演变内涵、分岔机理、设计综合及其应用

生产力发展与工程技术革新要求机构具备可自重组与可重构及“一机多用”的功能，以满足复杂工况需求。可重构机构具有可变活动度和可变构态，可以满足多任务、多工况与多功能的要求，然而，决定其设计方法的演变内涵与分岔机理的研究目前仍不为学者们充分了解。从变胞机构的演变与分岔机理的角度，以旋量理论、李群与李代数及微分流形为主要工具，揭示了机构演变内涵及运动与约束空间的内在关联关系；探究了机构演变中的分岔机理与可控奇异位形，回顾了变胞机构与折纸及折展机构的历史渊源，综述了变胞机构的构型设计、性能综合与新型设计理念及其创新应用。     

随车起重机伸缩臂截面多目标优化

为了提高某火箭炮弹药装填车随车起重机伸缩臂的结构刚度,减轻结构质量,建立了随车起重机伸缩臂参数化模型,并对伸缩臂在水平受载状态下进行仿真分析。以伸缩臂截面尺寸参数为设计变量,借助最优拉丁超立方试验设计建立样本空间,构造响应面多项式函数近似模型。在此基础上,利用NSGA-Ⅱ型遗传算法对伸缩臂自身重量、挠度进行多目标优化。优化结果表明:伸缩臂质量减轻了24.5%,减重效果明显。文中所采用的将参数化建模、有限元分析和数值寻优相结合的优化方法,可为起重机伸缩臂截面优化提供一定的参考。     

一种多功能液压试验台的设计

设计了一种多功能液压试验台,介绍了其工作原理、系统组成及主要技术参数。结合企业产品设计研发需要,试验台能满足液压阀、液压缸等多项测试。通过对试验台数据测试和数据采集系统的集成设计,设计开发了适合该试验台的数据分析软件。     

Modeling & optimization of renewable hydrogen production from biomass via anaerobic digestion & dry reformation

There is a growing interest in the usage of hydrogen as an environmentally cleaner form of energy for end users. However, hydrogen does not occur naturally and needs to be produced through energy intensive processes, such as steam reformation. In order to be truly renewable, hydrogen must be produced through processes that do not lead to direct or indirect carbon dioxide emissions. Dry reformation of methane is a route that consumes carbon dioxide to produce hydrogen. This work describes the production of hydrogen from biomass via anaerobic digestion of waste biomass and dry reformation of biogas. This process consumes carbon dioxide instead of releasing it and uses only renewable feed materials for hydrogen production. An end-to-end simulation of this process is developed primarily using Aspen HYSYS® and consists of steady state models for anaerobic digestion of biomass, dry reformation of biogas in a fixed-bed catalytic reactor containing Ni–Co/Al₂O₃ catalyst, and a custom-model for hydrogen separation using a hollow fibre membrane separator. A mixture-process variable design is used to simultaneously optimize feed composition and process conditions for the process. It is identified that if biogas containing 52 mol% methane, 38 mol% carbon dioxide, and 10 mol% water (or steam) is used for hydrogen production by dry reformation at a temperature of 837.5 °C and a pressure of 101.3 kPa; optimal values of 89.9% methane conversion, 99.99% carbon dioxide conversion and hydrogen selectivity 1.21 can be obtained.     

Predicting visual similarity between colour palettes

This work is concerned with the prediction of visual colour difference between pairs of palettes. In this study, the palettes contained five colours arranged in a horizontal row. A total of 95 pairs of palettes were rated for visual difference by 20 participants. The colour difference between the palettes was predicted using two algorithms, each based on one of six colour-difference formulae. The best performance (r² = 0.86 and STRESS = 16.9) was obtained using the minimum colour-difference algorithm (MICDM) using the CIEDE2000 equation with a lightness weighing of 2. There was some evidence that the order (or arrangement) of the colours in the palettes was a factor affecting the visual colour differences although the MICDM algorithm does not take order into account. Application of this algorithm is intended for digital design workflows where colour palettes are generated automatically using machine learning and for comparing palettes obtained from psychophysical studies to explore, for example, the effect of culture, age, or gender on colour associations.     

基于斯特林制冷机的文物恒湿展柜设计及实验研究

博物馆文物保存过程中相对湿度对文物的影响尤其重要，因此针对目前小型展柜广泛采用的半导体制冷存在制冷量小的缺点，结合斯特林制冷机制冷量大、寿命长、安全可靠等优点，设计并搭建了一台基于斯特林制冷的文物恒湿展柜装置，实现对微环境中相对湿度的精确调节。将斯特林制冷机的冷头置于优化设计的水槽中用于控制水温，采用空气与水直接接触的方式控制展柜内空气湿度。结果表明：使用散热片以及小型循环水泵可以大幅提升冷头与水之间的换热效率；合理的风机控制策略可以有效提升展柜湿度调节速度，维持湿度稳定，降低系统能耗；展柜内的相对湿度在45.0%～65.0%之间连续可调，并能保持稳定。