Evolution of Local Structural Ordering and Chemical Distribution upon Delithiation of a Rock Salt–Structured Li1.3Ta0.3Mn0.4O2 Cathode

Lithium‐rich disordered rock‐salt oxides have attracted great interest owing to their promising performance as Li‐ion battery cathodes. While experimental and theoretical efforts are critical in advancing this class of materials, a fundamental understanding of key property changes upon Li extraction is largely missing. In the present study, single‐crystal synthesis of a new disordered rock‐salt cathode material, Li_1.3Ta_0.3Mn_0.4O₂ (LTMO), and its use as a model compound to investigate Li concentration–driven evolution of local cationic ordering, charge compensation, and chemical distribution are reported. Through the combined use of 2D and 3D X‐ray nanotomography, it is shown that Li removal accompanied by oxygen oxidation is correlated with the development of morphological defects such as particle cracking. Chemical heterogeneity, quantified by subparticle level distribution of Mn valence state, is minimal during Mn redox, which drastically increases upon the formation of cracks during oxygen redox. Density functional theory and bond valence sum mismatch calculations reveal the presence of local short‐range ordering in the pristine oxide, which gradually disappears along with the extraction of Li. The study suggests that with cycling the transformation into true cation–disordered state can be expected, which likely impacts the voltage profile and obtainable energy density of the oxide cathodes.     

Adhesive element modelling and weighted static shape control of composite plates with piezoelectric actuator patches

A novel finite element model is presented for static and dynamic analysis of composite plates integrated with a laminated piezoelectric layer, a host laminated composite plate and an adhesive layer between them. A new adhesive element is developed which includes both peel and shear effects in the adhesive layer based on first‐order shear deformation plate theory. The thin adhesive layer between the piezoelectric layer and the host plate is modelled by assuming that it carries constant shear and peel strains throughout its thickness. In addition, a weighted static shape control scheme for finding the optimal voltage distribution for static shape control is given. By selecting different weighting matrices, a variety of items such as displacements, slopes, curvatures, strains and even generalized forces, can be included in finding the optimal actuating voltage for static shape control. The present model is validated by comparing with those results available in the literature. The numerical results show that the weighted linear least method can give a satisfactory voltage distribution to best match the desired shape. Copyright © 2004 John Wiley & Sons, Ltd.     

鸭池河水电站压力钢管外压稳定性设计

采用解析法和半解析有限元法分别对鸭池河水电站埋藏式加劲压力钢管进行外压稳定性计算。在计算分析过程中,考虑了初始缺陷因素对埋藏式加劲压力钢管抗外压稳定性的影响,使得计算结果更加接近于工程实际;从而为埋藏式加劲压力钢管的外压稳定性计算提出了一种更加行之有效的方法。     

居住建筑设计的点滴体会

根据石河子的地理位置、自然环境和居住建筑发展的历史,为当地设计了功能较全,布局合理,实用性强的住宅楼。通过设计实践对住宅设计提出了一些看法。     

圆柱壳结构外压弹塑性稳定性问题的半解析有限元法

本文综合考虑了几何、物理双重非线性因素的影响,对圆柱壳结构在承受外压作用下发生失稳屈曲进行了研究。几何方程采用大位移的应变位移关系,物理方程采用弹塑性分析的应力应变关系,导出了圆柱壳单元弹塑性分析的切线刚度矩阵。计算中,为了追踪失稳屈曲完整的平衡路径,在位于极值点邻域内的每一增量步中,我们采用控制弧长约束下的增量一迭代法进行计算,使计算效率大大提高。     

科卡金矿边坡岩石力学试验

通过岩石单轴压缩试验,获得岩石的基本力学性质指标,分析岩石的破坏形式,利用声发射装置探讨岩石试件在压缩过程中内部能量的变化及破坏过程。结果显示,边坡岩石属于硬质岩,在外荷载达到抗压强度时,瞬间发生破坏,破坏后岩石呈碎块状,表明该岩石破坏类型为脆性破坏。     

稠油乳化降粘剂S-5的研制及应用

针对注蒸汽开采稠油油藏过程中存在的问题，研制出耐高温高效稠油乳化降粘剂S-5，并对其提高注汽采油效果进行了研究。结果表明，伴蒸汽注入S-5可明显降低开发初期注汽压力，提高蒸汽驱替效率，降低产出液中含水量，提高注汽周期的产油量及油汽比。将降粘剂S-5用于井筒降粘，可有效提高稠油井产量，解决井筒举升困难的问题。该项技术在胜利油田和大港油田推广应用后，取得了良好的经济效益。     

A NEW METHOD FOR ACHIEVING DROPWISE CONDENSATION (Ⅱ) NEW SURFACE MATERIALS FOR DROPWISE CONDENSATION

Technology of ion-plating and ion-beam mixing was employed to prepare surface alloys on copper tubes. Elements chosen for the purpose are Cr, Fe, Al, N, Bi, Sb, Sn, Se and In. Excellant dropwise condensation of steam was then obtained on some external surfaces of these copper tubes and the mechanism for the dropwise condensation was analysed.The surface characteristics of the Cu-Cr and Cu-Fe alloy layers were analysed by using XPS, AES and AES-PRO of PHI-550 multiple function electron spectroscopy.     

A compressional-shear model for vibration control of beams with active constrained layer damping

In the modeling of the active constrained layer damping (ACLD) structures, the transverse displacements of the constraining layer and the host structures are usually assumed to be compatible. However, when performing active control, even a small difference between the transverse displacement of the constraining layer attached with actuator and that of the host structures bonded with sensor may destabilize the closed-loop control system. In order to understand the effect of incompatible transverse displacements, a model for the beam with ACLD in which both compressional vibration and shear damping are considered, is developed. In this model, the viscoelastic layer is modeled to carry not only the shear strain but also the peel strain. In addition, a thorough solution scheme to obtain the eigenvalues and frequency response of the closed-loop controlled beam is also given based on multiple shooting method. The effects of the compressional vibration on passive and active control are investigated through simulation examples. It is found that the compressional vibration can significantly affect the frequencies and damping ratios of higher-order modes of an actively controlled beam and may even destabilize the active control.