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991.
Zhenkun Ke Xin Cao Chuanli Shan Lifen Shi Pingping Wang Yong Yang Fengyang Zhao Jiedong Cui Jinwei Li Gang Zhou Min Guan Tao Yu 《Ceramics International》2021,47(14):19605-19613
The purpose of the current work was to research the effect of alkali metal oxide on the structure, thermal properties, viscosity and chemical stability in the glass system (R2O–CaO–B2O3–SiO2) systematically. Because the glass would emulsify when Li2O was added to the glass batch, this article did not discuss Li2O. The results showed that when the amount of Na2O was less than 4 mol.%, there was a higher interconnectivity of borate and silicate sub-networks in glass, as more mixed Si–O–B bonds were present in glass. The glass samples exhibited excellent thermal properties and chemical stabilities. As the amount of Na2O exceeded 4 mol.%, the interconnectivity of borate and silicate sub-networks was weakened. The thermal properties and chemical stabilities of the glass samples were reduced. The connectivity of the silicate sub-network was weakened slightly as the Na/K ratio varied, and the coefficient of thermal expansion (CTE) of the glass samples gradually increased, and the resistance to thermal shock (RTS) value gradually decreased. Moreover, the viscosity of the glass samples decreased with the ratio of Na/Si and Na/K increased. 相似文献
992.
993.
采用闭孔泡沫铝和铝合金板制备单层夹芯板和六种多层夹芯结构。通过分析胞孔变形模式和宏观变形模式,研究了夹层板和芯层数量对结构准静态压缩力学性能和吸能特性的影响机制。结果表明:夹层板通过调节芯层间应力状态使芯层逐层坍塌,减少了由倾斜变形带的形成和延伸所导致的多芯层同步变形、横向滑动以及两侧滑移,使结构具有更高的坍塌应力、平台应力、单位体积吸能量以及更小的致密应变;芯层数量的增加导致无夹层板结构中变形带的长度和数量增加,从而改变了其宏观变形模式,致使结构两侧滑移现象加剧,同时积累了有夹层板结构中多个芯层中的胞孔缺陷,因此影响了逐层稳定变形,导致致密应变增大,坍塌应力、平台应力和单位体积吸能量减小,致密应变处的吸能效率降低。与其他结构相比,三层泡沫铝夹层板具有最佳的抗压强度和吸能性能。 相似文献
994.
Bending deformation behaviors of solution treated (ST), natural aged (NA) and T6 tempered 6063 aluminum alloy sheets were studied by three-point bending tests. The changes of bending force, interior angle, bending radius and sheet thickness in the fillet region were analyzed by experimental measurements and numerical simulations. The results showed that the bending characteristics were strongly dependent on the heat treatment conditions. The T6 alloy sheets were bent more sharply and local plastic deformation occurred severely in the fillet region. However, the ST and NA alloy sheets exhibited relatively uniform bending deformation and large bending radius. The bending force of T6 alloy was the highest, followed by the NA alloy and that of the ST alloy was minimum. After unloading, as compared with the ST and NA alloys, the springback of T6 alloys was markedly larger. The aging time showed a positive sensitivity on the springback and non-uniform bending deformability. The bending characteristics are attributed to the combined effects of yield strength, yield ratio and coefficient of neutral layer. 相似文献
995.
996.
聚乙烯编织袋防滑剂- A用于提高编织袋安全防滑等性能。分别对主要原料、合成树脂、增粘树脂进行了筛选,并对各种原料的配比、合成工艺条件进行了研究。应用试验表明:防滑性能提高33% ~38 % ,热稳定性良好。 相似文献
997.
Decentralized output feedback controller design for nonlinear interconnected systems with unknown control direction and time‐varying delays 下载免费PDF全文
Changchun Hua Liuliu Zhang Xinping Guan 《International Journal of Adaptive Control and Signal Processing》2014,28(11):1160-1173
The decentralized output feedback control problem is considered for a class of large‐scale systems with unknown time‐varying delays. The uncertain interconnections are bounded by general nonlinear functions with unknown coefficients. The control direction parameters are unknown for each subsystem, which brings a challenging issue for decentralized controller design. To deal with this problem, we propose a new decentralized control scheme with the help of Nussbaum function. The decentralized filter is designed at first. By constructing Lyapunov–Krasovskii functional, we design the dynamic output feedback controller. It is rigorously proved that the closed‐loop system is asymptotically stable. Finally, the simulation is performed, and the results verify the effectiveness of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
998.
Ningning Guan 《Materials Letters》2009,63(15):1272-1274
Single-crystalline Fe3O4 nanosheets were obtained for the first time by simply adjusting the pH of a magnetite particle dispersion, using a hydrophilic terpolymer as stabilizer. We experimentally observed the magnetite nanoparticles spontaneous, template-free organization into nanosheets. This transformation occurs in an acidic environment at the zeta potential minimum by the abrupt, oriented self-assembly of polymer-stabilized magnetite particles at room temperature. The driving forces of the oriented self-assembly process includes the interplay of anisotropic dipolar forces, electrostatic interactions and isotropic van der Waals forces. 相似文献
999.
Jiuzhaigou in Sichuan has been classified as a world nature legacy by UNESCO. The hydrologic cycle is the research emphasis in this area. Using isotope technique of natural water can effectively trace water origin and transportation process, and reveal recharge and discharge relation of various water bodies and hydraulic connection about various hydrogeologic units. This has important applications and scientific significance for protecting and developing the precious natural resource.
相似文献1000.
通过对铝箔抗拉强度测定中各类影响因素的分析,建立起数学模型,实现对其不确定度的评定,以期在检测工作中减少误差。 相似文献