三分量阵列感应共面线圈系井眼影响研究

三分量阵列感应测井仪器是测量复杂地层信息的重要工具,消除共面线圈系的井眼影响是仪器设计与应用的关键。应用有限元软件,数值计算分析居中井眼中三分量阵列感应的共面线圈系与共轴线圈系的响应特性,对比共面线圈系实验室建模仿真与现场试验结果。结果表明:除最短子阵列,其余共面子阵列的井眼影响与共轴子阵列显著不同,井眼影响导致测井响应为负值;最长子阵列虽然井眼影响小,但趋肤效应影响严重,地层电导率测量范围比共轴线圈系小得多。通过计算分析共面线圈系在井眼周围不同泥浆和地层电导率时的涡流分布特性,揭示了共面线圈系与共轴线圈系差别较大的原因。提出新的2发1收线圈系结构,从几何因子角度分析了它在减小井眼影响、降低测井负响应等方面的优势。研究成果为三分量阵列感应测井仪器的研制和应用奠定了理论基础。     

含空位缺陷碳化硅纳米管的电子结构和光学性质

Based on first-principle calculations,the electronic structures and optical properties of a single-walled (7,0) SiC nanotube(SiCNT) with a carbon vacancy defect or a silicon vacancy defect are investigated.In the three silicon atoms around the carbon vacancy,two atoms form a stable bond and the other is a dangling bond.A similar structure is found in the nanotube with a silicon vacancy.A carbon vacancy results in a defect level near the top of the valence band,while a silicon vacancy leads to the formation of three defect levels in the band gap of the nanotube.Transitions between defect levels and energy levels near the bottom of the conduction band have a close relationship with the formation of the novel dielectric peaks in the lower energy range of the dielectric function.     

In situ observation of self-assembled Fe13Ge8 nanowires growth on anisotropic Ge (1 1 0) surface

Self-assembled iron germanide nanowires (NWs) were grown by directly depositing Fe onto a Ge (1 1 0) substrate, in an in situ ultra-high vacuum transmission electron microscope from 430 to 500 °C. All observed NWs had a similar length/width aspect ratio (～8:1) at all deposition temperatures, as well as the same elongation orientation with respect to the underlying Ge (1 1 0) substrate. The growth dynamics was investigated by real time observations of NWs growth at elevated temperatures. It is elucidated that the formation of NWs in similar shape at all deposited temperatures is attributed to the similar activation energy barriers in length and width of NWs, which can result in the constant growth rate independent of growth temperatures. Furthermore, the difference in pre-exponential factor along the length and width of growing islands arose due to the anisotropic constraint of the Ge (1 1 0) substrate, leading to the unique elongation of NWs. This growth dynamics suggests the possibility of uniform control of the morphology of self-assembled NWs, as well as other morphologies of bottom-up fabricated devices, at different deposition temperatures.     

用物元-可拓分析实现电能质量综合评价

采用物元-可拓学基元分析及关联函数,结合熵权法,建立了电能质量的客观评价模型。采用关联函数对单项指标进行度量,克服了集合方法不能准确度量指标,以及模糊隶属函数无法度量超出单项指标范围的缺陷;采用熵权法计算指标权重,克服了主观确定权重评价方法缺陷。最后通过实际算例验证了该方法的可行性。     

Photocatalytic hydrogen production enhancement of Z-Scheme CdS quantum dots/Ni2P/Black Ti3+–TiO2 nanotubes with dual-functional Ni2P nanosheets

The Z-Scheme CdS quantum dots/Ni₂P/Black Ti³⁺–TiO₂ nanotubes with dual-functional Ni₂P nanosheets are fabricated by a continuously electrospinning-annealing/reduction-chemical deposition method, there, the TiO₂ nanotubes are fabricated via electrospinning, subsequently, the 2D Ni₂P lamellas grow on the surface of nanotubes and the Ti³⁺/O_v ions are introduced by reduction, then CdS QDs are deposited on the surface of Ni₂P lamellas. Evaluated by the photocatalytic hydrogen production, the photocatalytic performance of Z-Scheme CdS QDs/Ni₂P/B–TiO₂(~3303.85 μmol/g h) exhibits an obvious enhancement of about ~70 folds than unmodified TiO₂. The main reasons for the HER enhancement are ascribed to that the Pt-like behavior 2D Ni₂P and Ti³⁺ ions can accelerate the photo-generated electrons diffusing into water and reduce H₂ activation barrier, the Z-Scheme heterojunction can accelerate the separating and transferring of photo-generated charge carriers, the O_v ions and hollow nanotubes can increase solar utilization, which can be supported by the electrochemical measurements.