The effect of nanohybrid materials on the pour-point and viscosity depressing of waxy crude oil

The pipeline transportation of waxy crude oil is a problem both at home and abroad.In this paper,a novel nanohybrid pour-point depressant (PPD) was used to decrease the pour point and viscosity of waxy crude oil.The pour point and apparent viscosity of waxy crude oil was decreased significantly upon addition of the nanohybrid PPD,and the long-term stability of the nanohybrid PPD was superior to that of a conventional ethylene-vinyl acetate copolymer PPD.Polarized optical microscopy and X-ray diffraction were used to study the effect of the nanohybrid PPD on the crystallization of crude oil.Addition of the nanohybrid PPD reduced the amount of wax crystals,prevented their aggregation,and reduced the temperature at which the crude oil started to crystallize.The significant effect of this nanohybrid PPD on the pour point and viscosity depressing of crude oil is of great importance for facilitating the safe,efficient and energy-minimized transportation of waxy crude oil.     

Lushan M_S7.0 earthquake:A blind reserve-fault event

In the epicenter of the Lushan MS7.0 earthquake there are several imbricate active reverse faults lying from northwest to southeast,namely the Gengda-Longdong,Yanjing-Wulong,Shuangshi-Dachuan and Dayi faults.Emergency field investigations have indicated that no apparent earthquake surface rupture zones were located along these active faults or their adjacent areas.Only brittle compressive ruptures in the cement-covered pavements can be seen in Shuangshi,Taiping,Longxing and Longmen Townships,and these ruptures show that a local crustal shortening occurred in the region during the earthquake.Combining spatial distribution of the relocated aftershocks and focal mechanism solutions,it is inferred that the Lushan earthquake is classified as a typical blind reverse-fault earthquake,and it is advised that the relevant departments should pay great attention to other historically un-ruptured segments along the Longmenshan thrust belt and throughout its adjacent areas.     

非均匀材料反平面裂纹问题的特征函数

针对非均匀材料的线弹性断裂力学基本理论问题，从理论上探讨了将均匀材料的特征函数结构即Williams解推广到非均匀材料的合理性；并以反平面问题为例，给出了该问题任意阶特征函数的定解方程；进一步给出了非均匀材料反平面问题的Williams型解．该特征函数解从理论上揭示了非均匀性对裂纹尖端场结构的影响．     

基于等效磁路法的平动式啮合电动机静态转矩求解

阐述了平动式啮合电动机的结构和工作原理并采用等效磁路法建立了平动式啮合电动机的准线性分析模型。通过分析电机二维磁场分布和考虑电机特殊的电磁结构,提出了用三种磁通管单元来近似磁场分布,并借用磁力线和等磁位线互换的方法,将磁力线分布不均匀的磁通管引入到分析模型中,有效的处理了平动式啮合电动机中的磁场分布不均匀和磁路局部饱和,使分析模型得到简化并兼顾了求解精度。其静态转矩计算结果与有限元结果相吻合,验证了分析模型的合理性和准确性,表明该模型可以作为平动式啮合电动机结构优化设计的有效分析手段。     

任务型履带单兵机器人系统设计与越障性能分析

军事用途机器人的应用很大程度上降低了士兵及工作人员作业的危险性,针对当前单兵机器人普遍具有的结构复杂、携带不便等问题,设计并研制了一种便于携带的任务型单兵机器人,其轻质、灵活的特点可快速响应侦察、排爆、采样等任务的需要。为分析机器人的越障机理并提高越障性能,通过建立质心运动学模型,对机械臂俯仰角、机器人俯仰角与凸台越障最大高度进行理论分析,并通过仿真实验得到了机械臂不同姿态下机器人越障的质心位置变化曲线以及对应的驱动转矩曲线,以此确定了最佳越障姿态,最终通过实物实验验证了结构设计的合理性及理论分析的正确性。为后续单兵机器人的发展和移动机器人越障性能的改善提供参考。     

场效应纳电子晶体管的构造和电学特性测量

研究了场效应纳电子晶体管构造过程中金属电极的结构设计,源-漏电极高度、SiO₂绝缘层厚度以及金属电极选材等因素对器件性能有关键的影响。在此基础上测量了单壁碳纳米管束的场效应行为,构造成功基于单壁碳纳米管束的场效应晶体管。     

视觉意识相关的ERP成分及研究简评

关于人类意识(尤其视觉意识)的研究越来越多,其中包括各种实验范式(如掩蔽、双眼竞争、注意瞬脱、变化视盲等)与研究方法(如行为实验、ERP以及fMRI).本文主要对使用ERP(事件相关电位)技术考察视觉意识的研究进行综述,并对视觉意识相关的ERP成分进行简要介绍.众多研究发现,主要有3个ERP成分与视觉意识相关,即P1,"视觉意识负波"(VAN,刺激呈现大约200ms之后出现的一个负波)和晚期正成分(LP)或者P3(刺激呈现大约300ms之后出现的正成分).在这3个成分上,意识到的刺激都比未意识到的刺激所诱发波形的波幅更大.本文简要介绍了一些相关研究,并从不同注意成分与意识的关系、C1成分与意识、高层次意识的ERP研究、影响视觉意识时间进程的因素等角度,对未来的研究方向提出了一些设想.     

纳米SiO2对Vac乳液聚合及乳液性能影响的研究

采用原位乳液聚合法制备了聚醋酸乙烯酯（VAc）／纳米SiO2复合乳液,考察了纳米SiO2对VAc乳液聚合过程和乳液性能的影响．结果表明：纳米SiO2对VAc转化率和接枝率有一定影响;复合乳液中乳胶粒的形态、乳液的粘接强度、热稳定性和粘度等均明显不同于常规乳液。     

Paragenesia of Quaternary pediments and river terraces on the north piedmont of Wutai Mountains

A study has been made of the paragenetic relations of the pediments and river terraces on the northern piedmont of Wutai Mountains via geomorphologic mapping of 1:10000 scale, and an analysis on the role of tectonic, climatic, and drainage factors in the parageneses. The Quaternary pediments and river terraces on the north piedmont of Wutai Mountains united to constitute six steps of geomorphic surfaces. The episodic uplifting of fault blocks was the dominant factor in the formation of the unified surfaces, however climatic change and drainage diversities led to undulation of the surfaces. The second terrace of Yangyan River (T2) was formed in the last glacial maximum, when the river was in aggradational state. The third to fifth terraces were formed in interglacial stages, when the river was in equilibrium or degradational state. It is inferred that climate had no insignificant effect on the river incision caused by tectonic uplifting. In light of terraces dating, since the Quaternary the Wutai fault-block mountains experienced six rapid uplifting events, and the starting time of the last four events was respectively 1.2, 0.6, 0.13, and 0.02 Ma B.P.