Magnetically encoded 3D mesostructure with high-order shape morphing and high-frequency actuation

Inspired by origami/kirigami, three-dimensional (3D) mesostructures assembled via a mechanics-guided approach, with reversible and maneuverable shape-morphing capabilities, have attracted great interest with regard to a broad range of applications. Despite intensive studies, the development of morphable 3D mesostructures with high-order (multi-degree-of-freedom) deformation and untethered high-frequency actuation remains challenging. This work introduces a scheme for a magnetically encoded transferable 3D mesostructure, with polyethylene terephthalate (PET) film as the skeleton and discrete magnetic domains as actuation units, to address this challenge. The high-order deformation, including hierarchical, multidirectional and blending shape morphing, is realized by encoding 3D discrete magnetization profiles on the architecture through ultraviolet curing. Reconfigurable 3D mesostructures with a modest structural modulus (∼3 GPa) enable both high-frequency (∼55 Hz) and large-deformation (∼66.8%) actuation under an alternating magnetic field. Additionally, combined with the shape-retention and adhesion property of PET, these 3D mesostructures can be readily transferred and attached to many solid substrates. On this basis, diverse functional devices, including a switchable colour letter display, liquid mixer, sequential flashlight and biomimetic sliding robot, are demonstrated to offer new perspectives for robotics and microelectronics.     

Cyclic-anion salt for high-voltage stable potassium-metal batteries

Electrolyte anions are critical for achieving high-voltage stable potassium-metal batteries (PMBs). However, the common anions cannot simultaneously prevent the formation of ‘dead K’ and the corrosion of Al current collector, resulting in poor cycling stability. Here, we demonstrate cyclic anion of hexafluoropropane-1,3-disulfonimide-based electrolytes that can mitigate the ‘dead K’ and remarkably enhance the high-voltage stability of PMBs. Particularly, even using low salt concentration (0.8 M) and additive-free carbonate-based electrolytes, the PMBs with a high-voltage polyanion cathode (4.4 V) also exhibit excellent cycling stability of 200 cycles with a good capacity retention of 83%. This noticeable electrochemical performance is due to the highly efficient passivation ability of the cyclic anions on both anode and cathode surfaces. This cyclic-anion-based electrolyte design strategy is also suitable for lithium and sodium-metal battery technologies.     

工程量清单计价对造价咨询机构业务的影响及对策

随着我国的入世和建筑业的逐步对外开放,按国际惯例进行工程量清单计价已成为造价咨询机构必须面对的问题。长期以来,我国实行的是以定额为主的计价模式,属于计划经济的范畴,已不能适应改革开放的需要。因此工程计价改革势在必行。工程造价咨询业是近几年发展起来的社会中介机构,为了加快建筑工程计价模式与国际接轨的步伐,必须建立以工程量清单为计价平台的工程计价模式。通过了解和分析工程量清单计价的计算规则、分部分项工程项目的划分,以及清单计价的特点和清单计价与定额计价的区别,才能立于不败之地。     

基于红色基因传承的高校爱国主义教育实践路径研究

红色基因融入高校爱国主义教育,为基于红色基因传承的高校爱国主义教育的发展奠定理论基础。基于红色基因传承的高校爱国主义教育的实践路径应该实现第一课堂和第二课堂协同发展,筑牢爱国主义教育主阵地、线上教育与线下教育有机结合,畅通爱国主义教育主渠道、教育主体与教育客体双向互动,强化爱国主义教育主战线等方面入手。运用多形式、多媒体和多渠道将红色基因融入高校爱国主义教育的全过程,使红色教育资源在爱国主义教育中发挥最大效用。     

Webquest在信息检索课教学中的应用

介绍Webquest的概念、特点和组成,并将其应用于信息检索课教学,同时指出信息检索课使用Webquest应注意的问题。     

电子纸阅读器及其对数字图书馆的影响

指出数字图书馆大规模发展的两大难题:缺乏合适的阅读介质和盗版导致的版权问题,认为可以使用电子纸阅读器作为数字图书理想的阅读介质,使用封闭式系统与硬件加密对抗盗版。并分析电子纸阅读器对数字图书馆的积极影响。     

基于遗传算法的预测指标信息提取方法研究

建立预测模型时,选择合适的自变量集合很重要。指标太多会增加数据采集的工作量和问题分析的复杂性;盲目减少指标又会损失很多信息,容易产生错误的结论。因此需要找到一个合理的信息提取方法,在减少分析指标的同时,尽量减少原指标包含信息的损失。通过应用遗传算法技术,根据预测模型的预测正确率来选择指标,建立了基于遗传算法的预测模型指标的自动提取模型。实验应用表明,利用遗传算法提取预测模型的指标信息效果比较好,优于神经网络和决策树模型。     

Material research from the viewpoint of functional motifs

As early as 2001, the need for the ‘functional motif theory’ was pointed out, to assist the rational design of functional materials. The properties of materials are determined by their functional motifs and how they are arranged in the materials. Uncovering functional motifs and their arrangements is crucial in understanding the properties of materials and rationally designing new materials of desired properties. The functional motifs of materials are the critical microstructural units (e.g. constituent components and building blocks) that play a decisive role in generating certain material functions, and can not be replaced with other structural units without the loss, or significant suppression, of relevant functions. The role of functional motifs and their arrangement in materials, with representative examples, is presented. The microscopic structures of these examples can be classified into six types on a length scale smaller than ∼10 nm with maximum subatomic resolution, i.e. crystal, magnetic, aperiodic, defect, local and electronic structures. Functional motif analysis can be employed in the function-oriented design of materials, as elucidated by taking infrared non-linear optical materials as an example. Machine learning is more efficient in predicting material properties and screening materials with high efficiency than high-throughput experimentation and high-throughput calculations. In order to extract functional motifs and find their quantitative relationships, the development of sufficiently reliable databases for material structures and properties is imperative.     

浅析教育的公共服务性

随着构建社会主义和谐社会的深入和构建服务型政府理念的兴起,教育事业被赋予了一种全新的社会属性,即公共服务性。基于新公共服务对政府职能的重新定位,在新的历史条件下,教育公共服务性可作三个方面的理解,即教育公共服务的责任主体;教育公共服务的核心价值;教育公共服务的方式。     

学术文本词汇功能识别——在关键词自动抽取中的应用

传统的关键词自动抽取常以候选词的出现频次、位置等非语义信息构建特征,并未考虑关键词在学术文献中承担的特定语义角色,即词汇功能。通过对现有数据统计,本文发现作者标注关键词中约有67.99%是研究问题或研究方法词。因此,本文将关键词的词汇功能分为三类:"研究问题""研究方法"和"其他",在传统的词频特征以及位置特征基础上,融合词汇功能特征,使用计算机领域的学术文献基于分类和排序两种思想进行关键词抽取实验。实验结果表明,融合词汇功能后,关键词抽取效果得到明显提升。相较于基准实验,二分类模型的准确率Acc和F值分别相对提升24.63%和25.19%,达到了0.840和0.666;排序模型的MAP、NDCG@5和P@5分别相对提升168.32%、189.50%和148.30%,提升至0.813、0.828和0.447,证明了学术文献词汇功能特征在关键词自动抽取中具有重要作用。