An overview of recent progress in the development of flexible electrochromic devices

Electrochromic materials are capable of reversibly switching their colors or optical properties through redox reactions under applied voltages,which have shown great potential applications including smart windows,nonemissive displays,optical filters,among others.Although the current rigid electrochromic devices have shown emerging interest and developed rapidly,many applications(e.g.,wearable/deformable optoelectronics)are blocked due to their inflexible features.Herein,the adaption of rigid electrochromic devices to flexible ones is of particular interest for the new era of smart optoelectronics.In this review,the current state-of-the-art achievements of flexible electrochromic devices(FECDs)are highlighted,along with their design strategies and the choice of electrochromic materials.The recent research progress of FECDs is reviewed in detail,and the challenges and corresponding solutions for real-world applications of FECDs are discussed.Furthermore,we summarize the basic fabrication strategies of FECDs and their potential applications.In addition,the development trend,the perspectives,and the outlook of FECDs are discussed at the end of this Review,which may provide recommendations and potential directions to advance the practical applications of FECDs.

A NOTE ON LI-YAU-TYPE GRADIENT ESTIMATE

In this article, we obtain Li-Yau-type gradient estimates with time dependent parameter for positive solutions of the heat equation that are different with the estimates by Li-Xu [21] and Qian [23]. As an application of the estimate, we also obtained slight improvements of Davies' Li-Yau-type gradient estimate.

基于应变梯度理论和逆有限元法的Timoshenko梁形状传感建模

大型结构的几何非线性变形严重威胁着结构体系的安全.因此,对在役结构变形进行实时监测具有重要意义.然而,目前基于线弹性理论提出的逆有限元法(iFEM)并不适用于非线性变形,为此,提出了一种非线性逆有限元法来建立结构形状感知模型.首先给出了应变梯度Timoshenko梁模型的运动学和动力学变量,并建立了其几何非线性变形控制方程.然后,推导出了转角函数的解析解,并建立了非线性形状感知模型.其中,采用等几何分析(IGA)方法构造插值形状函数.由于位移函数以旋转形式表示,所以可以有效地避免“剪切锁定”问题.随后,利用离散表面应变测量值推导出了实际转角函数,并建立了转角自由度在直角坐标系与曲线坐标系之间转换关系.最后,以一悬臂梁为例,将重构位移与理论位移进行了比较.数值结果表明,不论是集中荷载还是分布荷载,所提的非线性逆有限元法均具有良好的重构性能,重构误差都小于2.5%.

老而弥新:耦合型开放式创新驱动的中国制造企业服务化和数字化协同共演研究

随着全球制造企业外部环境日趋开放,中国制造企业正处于“创新驱动”引领的服务化和数字化双重叠加态势下,但其演化过程和实现机制不甚清晰。本文以一家拥有91年历史的中国制冷行业“活化石”——大连冰山集团有限公司(以下简称“冰山集团”)为例,探讨耦合型开放式创新对企业服务化和数字化的影响以及企业服务化与数字化动态协同演化过程两个研究问题。研究发现:(1)多维机会窗口下,耦合型开放式创新呈现出创新模式的差异化堆垒配置以及合作对象的多元化时序协同2个特征。(2)耦合型开放式创新与企业服务化和数字化相互影响、相互促进。企业服务化演化经历“探索—参与—扩展—应用”过程,与之相对,企业数字化演化经历“启动—发展—实施—应用”过程。(3)服务化与数字化在协同演化和动态融合中依次形成基于互联网的产品服务系统、基于物联网的产品服务系统和智能产品服务系统3种演化结果。(4)整个动态协同演化依次表现为“外需倒逼式”“资本助推式”“制度引致式”“场景驱动式”4种演化模式。不同阶段间遵循“开发增量用户”“强化用户黏性”“重设组织身份”3种核心实现机制。本文能够贡献于现有文献对于开放式创新、服务化和数字化关系考量不足造成的研究缺口,同时建立起企业服务化和数字化间的对应关系,对数字经济时代老字号制造企业重新焕发活力具有一定的启发意义。

Light-responsive color switching of self-doped TiO_(2-x)/WO_(3)·0.33H_(2)O hetero-nanoparticles for highly efficient rewritable paper

Smart materials that reversibly change color upon light illumination are widely explored for diverse appealing applications.However,light-responsive color switching materials are mainly limited to organic molecules.The synthesis of inorganic counterparts has remained a significant challenge because of their slow light response and poor reversibility.Here,we report a seeded growth strategy for the synthesis of TiO_(2-x)/WO_(3)·0.33H_(2)Ohetero-nanoparticles(HNPs)with networked wire-like structure of〜10 nm in diameters that enable the highly reversible light-responsive color switching properties.For the TiO_(2-x)/WO_(3)·0.33H_(2)OHNPs,T P species self-doped in TiO_(2-x)nanoparticles(NPs)act as efficient sacrificial electron donors(SEDs)and Ti-O-W linkages formed between TiO2-x and WO30.33H2O NPs ensure the nanoscale interfacial contact,endowing the HNPs enhanced photoreductive activity and efficient interfacial charge transfer upon ultraviolet(UV)illumination to achieve highly efficient color switching.The TiO_(2-x)/WO_(3)·0.33H_(2)OHNPs exhibits rapid light response(<15 s)and long reversible color switching cycles(>180 times).We further demonstrate the applications of TiO_(2-x)/WO_(3)·0.33H_(2)O HNPs in ink-free,light-printable rewritable paper that can be written on freehand or printed on through a photomask using UV light.This work opens an avenue for designing inorganic light-responsive color switching nanomaterials and their smart applications.

Interference mechanism and damage accumulation in high-speed cross scratches on hard brittle materials

Precision and low damage grinding of aviation optical elements can effectively improve the overall processing efficiency.The mechanism of high-speed cross scuffing of multiple abrasive particles has become an important factor affecting the forming quality of workpiece.Interaction of abrasive trajectory determines machined surface and subsurface morphology and damage.According to the relative motion trajectory of wear particles on the workpiece surface,a theoretical model of the trochoidal trajectory intersection angle is proposed.High-speed scratches with different cross angles are experimentally obtained to explore the interference mechanism and damage accumulation of cross scratches.The results indicate that the Crack system I and Crack system II,produced by the two cross scratches,are mainly based on the stress principle and the strength principle,respectively.An increase in the damage radius is observed with a decrease in the crossing angle.Furthermore,as the duration of the normal cutting force decomposition curve at the entrance/exit of the intersection increases,the half-peak width also increases.The accumulation of cross-scratch damage promotes the propagation of deep subsurface lateral and median cracks.In other words,damage accumulation and interference mechanism formed by the cross scratches increase the longitudinal depth and lateral length of the damage.