摇摆参数对自然循环系统混沌脉动影响分析

针对摇摆参数对自然循环系统中流量混沌脉动的影响,用非线性时序分析的方法对实验结果进行了分析研究.基于相空间重构理论,计算不同摇摆参数下时间序列的关联维(CD)、K2熵和最大Lyapunov指数(MLE)等几何不变量值,根据计算结果分析摇摆参数对自然循环系统混沌脉动的影响.分析结果表明:摇摆周期越短、摇摆振幅越大,混沌出现时的无量纲功率越大;摇摆周期对混沌脉动边界的影响大于摇摆振幅的影响;当摇摆周期为5 s时,由于摇摆引起的波谷型脉动与密度波型脉动频率相近而发生共振作用,流量脉动的混沌特征减弱.     

两输入幂激励前向神经网络权值与结构确定

基于多元函数逼近与二元幂级数展开理论,构建了一个以二元幂函数序列为隐神经元激励函数的两输入幂激励前向神经网络模型.以该网络模型为基础,基于权值直接确定法以及隐神经元数目与逼近误差的关系,提出了一种网络权值与结构确定算法.计算机仿真与数值实验结果验证了所构建的网络在逼近与去噪方面具有优越的性能,所提出的权值与结构确定算法能够快速、有效地确定网络的权值与最优结构,保证网络的最佳逼近能力.     

二连盆地阿南凹陷辫状河三角洲砾岩储集层微相模式及含油性

通过对二连盆地阿南凹陷大量岩性剖面、测井曲线、岩石学特征、储集性能、沉积构造和沉积韵律分析,认为阿南凹陷下自垩统阿尔善组第三段砾岩,是一次大的事件性沉积和近物源、粗碎屑.低成分成熟度和低结构成熟度的多源复成分砾岩.首次提出阿三段砾岩属大型辫状河三角洲相,具有三角洲所具备的三角洲平原、三角洲前缘和前三角洲的三层结构,存在以牵引流为主的沉积构造和正韵律为主的剖面特征.最终细分出水下河道等十个微相,恢复了阿三段的岩相古地理环境,建立了相模式.指出,砾岩的储集空间为原生砾间孔、砾间洞、粒间缝、次生溶蚀孔和构造缝.砾岩的储集性能、含油性好坏和油藏展布受沉积微相、砾石支撑方式和构造缝发育程度的严格控制.     

基于虚拟仪器三相突然短路试验数据处理的算法研究

提出了将参数辨识中的Marquate算法应用于虚拟仪器的三相突然短路试验数据处理，介绍了Marquate算法理论。通过试验数据和传统的仪表记录数据手工处理的结果进行了比较，改进后的算法具有过程简化，结果更准确的优点。     

类铀矿岩材料制备及氡扩散系数测定的实验研究

扩散过程是主导氡在铀矿岩中运移与析出的主要方式。铀矿原岩辐射较大且取样困难,不利于开展有关室内实验。为了解决以上问题,依据相似理论,以某花岗岩为原型,选取石英砂、铀尾砂、水泥、精铁粉和微硅粉等为原材料,制备了3种不同材料配比的圆柱形类铀矿岩试样,并测定了原型和试样的物理力学参数;然后采用密闭腔体法测量了原型和试样在不同包裹方式下的累积氡浓度,推导氡的扩散性能参数的计算公式,通过计算获得了原型和试样的氡扩散长度和扩散系数。实验结果表明:花岗岩原型与所制备的类铀矿岩的颗粒密度、抗压强度、抗拉强度、内聚力和内摩擦角相似比的均值分别为1.09∶1、3.93∶1、4.28∶1、3.47∶1和1.00∶1;花岗岩原型的扩散系数为0.146×10^-6m²·s^-1,类铀矿岩的扩散系数介于0.114×10^-6～0.594×10^-6m²·s^-1之间,两者的相似比介于0.25∶1～1.28∶1之间。研究认为所制备的试样3在一定程度上可用来模拟花岗岩型铀矿岩,以满足室内实验的需求。     

Effects of water molecules on the formation of transfer films and the occurrence of superlow friction

The establishment of superlow friction in moist air is very important for the engineering application of hydrogenated diamond-like carbon (H-DLC) films. Nevertheless, water molecules in the surrounding atmosphere always result in the failure of the near-frictionless state. This work aims to explore the effects of water molecules in the environment and the material of the counterparts on the tribological performance of a composite structure prepared by depositing MoS₂ on a H-DLC film. The results indicated that the existence of water molecules in the atmosphere is beneficial for achieving stable superlubricity for the material system because it helps retain the in-situ formed MoS₂ transfer film on the counterpart. In the presence of water molecules, the wear interface was replaced by a robust and incommensurate MoS₂ tribolayer/H-DLC sliding interface, which was responsible for the superlow friction achieved in this work. The results also revealed that the ZrO₂ counterpart was capable of retaining the as-formed MoS₂ transfer film and establishing long-lasting superlow friction even in dry air. The mechanisms behind this phenomenon are also discussed in this paper.     

棒束通道内环状流气液界面行为及形成机理研究

棒束通道中环状流气液界面行为的研究，能为压水堆的事故处理和沸水堆电厂的正常运行提供数据和理论支撑。本研究针对3×3棒束通道中环状流气液波状界面形式进行记录与分析，绘制详细的环状流流型图，并针对其形成机理进行分析。结果表明：棒束通道中的环状流主要有搅混型、未全润湿、平滑边界型、单一波状流、包状扰动波、带状扰动波和带状扰动波叠加液相丧失7种形式；单一波状流是当气相速度较高、液相速度较低时，气液界面上发生的有固定波峰和波谷、以固定速度向上运动的流动形式，其现象可通过Kelvin-Helmholtz型不稳定性理论来解释；当液相流量升高或气相流量减少时，发生单一波状流界面失稳，界面能量增加，进入到包状扰动波或带状扰动波阶段；当能量超过1.6 kPa²/Hz时，界面能量超过底层液膜束缚能力，产生液相丧失型环状流。     

Visible light driven photodynamic anticancer activity of graphene oxide/TiO2 hybrid

Graphene oxide/TiO₂ hybrid (GOT) was prepared by using Ti(OC₄H₉)₄ and graphene oxide (GO) as reactants. Superior adsorption and photocatalysis performance under visible radiation were achieved in the presence of the GOT rather than in unmodified TiO₂. GO that no toxicity in vitro acted as electron sink in GOT efficiently enhance the photodynamic activities. Consistent with photocatalytic performance of TiO₂, GOT generated reactive oxygen species after visible light irradiation both in cell free condition and in vitro. No dark cytotoxicity was observed using 0–100 μg/mL GOT during long incubation time. In parallel, following exposure of cells to GOT and irradiation, a marked decrease in mitochondrial membrane potential, cell viability, activities of superoxide dismutase, catalase and glutathione peroxidase, as well as increased malondialdehyde production were observed. Moreover, GOT caused significant elevation in caspase-3 activity, and induced apoptotic death. The results indicated that GOT had excellent photodynamic anticancer activity without dark cytotoxicity.     

基于多尺度的贝叶斯模型显著性检测

针对传统基于贝叶斯模型的显著性检测算法存在准确率不理想的问题,提出了一种基于多尺度的贝叶斯模型显著性检测算法。通过超像素分割算法(SLIC)将原图分割成不同尺度的超像素,根据超像素边界信息得到背景种子,进而通过距离计算和多尺度融合得到背景先验;对原图进行颜色增强,采用Harris算子对增强图进行检测角点求得凸包,融合不同尺度下的超像素得到凸包先验;融合背景先验和凸包先验得到最终先验;利用颜色直方图和凸包计算似然概率;将最终先验和似然概率通过贝叶斯模型计算显著图。在公开数据集MSRA1000、ECSSD上与多种传统算法进行准确率和召回率对比,该算法有更好的表现。