共查询到10条相似文献，搜索用时 46 毫秒
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Hai-Ping Cheng Lin-Lin Wang Mao-Hua Du Chao Cao Ying-Xia Wan Yao He Krishna Muralidharan Grace Greenlee Andrew Kolchin 《Journal of Computer-Aided Materials Design》2006,13(1-3):161-183
Over the past 6 years, we have engaged in a multi-faceted computational investigation of water–silica interactions at the fundamental physical and chemical level. This effort has necessitated development and implementation of simulation methods including high-accuracy quantum mechanical approaches, classical molecular dynamics, finite element techniques, and multi-scale modeling. We have found that water and silica can interact via either hydration or hydroxylation. Depending on physical conditions, the former process can be weak ( < 0.2 eV) or strong (near 1.0 eV). Compared to hydration, the latter process yields much larger energy gains (2–3 eV/water). Some hydroxylated silica systems can accept more water molecules and undergo further hydroxylation. We have also studied the role of external stress, effects of finite silica system size, different numbers of water molecules, and temperature dependences. 相似文献
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Within the operations management literature, quality management (QM) has been one of the most popular research areas over the last two decades. QM is an integrative management philosophy aimed at the continuous improvement of performance. Consequently, the impact of QM practices on firm performance has been the subject of constant interest and challenge among researchers. Numerous empirical studies have attempted to investigate QM practice–performance relationships in different contexts. Based on an extensive review of the literature, this paper attempts to reflect the research stream on the impact of QM on firm performance and to provide insights for future research. For this purpose, the reviewed QM literature is organised and classified along three main themes: QM practices, performance and QM–performance relationships. 相似文献
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SiO2/聚碳酸酯纳米相复合材料的制备与性能 总被引：20，自引：0，他引：20
通过溶胶－凝胶过程制备了ＳｉＯ２／ＰＣ复合材料,透射电镜分析表明,ＳｉＯ２／ＰＣ在１／９到２．５／７．５范围内,ＳｉＯ２形成３００－４００ｎｍ的颗粒分散在ＰＣ连续相中。热失重分析表明,材料的热稳定性随ＳｉＯ２含量的增加而提高。扭辫分析表明,材料的玻璃化转变温度比ＰＣ提高２０℃以上。 相似文献
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通过电镜分析及理论推导对羟基磷灰石( Hydroxyapatite, HA) /高密度聚乙烯( High density polyethylene, HDPE) 复合材料界面粘结状态、HA 颗粒对裂纹扩展的钝化、钉扎作用、复合纤维对体系分子热激活能的影响及复合纤维的能量吸收机制与增强增韧等进行了深入研究。结果表明: HA/HDPE 复合材料通过纳米HA 颗粒与 HA/HDPE 复合纤维在不同尺度上协同作用达到增强增韧的效果。即在纳米尺度, 纳米HA 颗粒的均匀分散和高的HA/HDPE 界面结合强度显著提高了HDPE 的结晶度, 细化了HDPE 晶粒尺寸, 并在HA 颗粒表面形成取向结晶层, 从而使材料在断裂过程中通过HDPE 取向结晶层的基体形变和HA 脱粘过程对微裂纹起钝化和钉扎作用, 并扩大能量耗散的区域, 以阻滞微孔隙和银纹的长大和破断, 抑制大裂纹的早期形成。在微米尺度, 由于HA/HDPE 复合纤维的定向排列, 使体系的活化体积显著降低, 大大增加了材料的断裂热激活能, 从而显著提高材料的强度。另一方面, 复合纤维在应力作用过程中通过纤维断裂、纤维拔出、裂纹偏转机制使材料在形变与破坏过程中耗散更多的能量, 从而显著提高材料的强度和韧性。 相似文献