基于FP-Tree的概念格量化约简及其在GIS的应用

GIS的空间数据具有海量性、复杂性的特点,为了能更有效的挖掘隐藏在GIS中的知识引入了概念格技术。然而,又为了解决关联规则生成算法效率低、构造Hasse图效率低及冗余多的问题,提出在FP-Tree的基础上直接生成经过量化约简的频繁概念格。将该算法应用于GIS的空间数据挖掘取得了实际可行的应用结果。     

Promoting Ethylene (co)Polymerization in Aliphatic Hydrocarbon Solvents Using tert-Butyl Substituted Nickel Catalysts

In the past few decades,the development of high-performance catalysts has been a key driving force and a center of research efforts in the field of olefin polymerization.However,a major discrepa ncy exists between in dustrial researches which utilize aliphatic hydrocarb on solventsz and academic researches which predominantly focus the catalytic properties in aromatic solvents.In this con-tribution,a novel diaryl-methyl aniline bearing eight tert-butyl groups was prepared and subsequently transformed to four different kinds of imine-type ligands.The corresponding nickel complexes as well as their counterparts derived from diphenyl-methyl aniline without the tert-butyl groups were prepared and investigated in ethylene polymerization.     

LiS分子和离子基态的精确理论研究

Potential energies of LiS(²Π), LiS^-(¹Σ⁺) and LiS⁺(³Σ^-) are calculated by using the multireference configuration interaction method including Davidson correction and the augmented correlation-consistent basis sets aug-cc-PV(X+d)Z (X=T, Q). Such obtained potential energies are subsequently extrapolated to the complete basis set limit. Both the core-valence correction and the relativistic effect are also considered. The analytical potential energy functions are then obtained by fitting such accurate energies utilizing a least-squares fitting procedure. By using such analytical potential energy functions, we obtain the accurate spectroscopic parameters, complete set of vibrational levels and classical turning points. The present results are compared well with the experimental and other theoretical work.     

Transition metal doping of amorphous silica particles

Amorphous, homogeneously doped particles with 1–10 atomic percent (at%) nickel or zinc, smaller than 100 nm, were synthesized. Additionally, 20 at% nickel and zinc-doped silica particles were synthesized, although the particle size was > 300 nm. The coordination state of the metal in solution did not change with the ammonia or water concentrations used. Particle size was found to decrease with both increasing water and ammonia hydroxide concentrations. The NH₄OH concentrations of 4.5 and 6.5 M used allowed the formation of ammine–transition metal complexes and the zeta potential to remain in a stable range, allowing for spherical, nearly monodisperse particle formation at high metal dopant concentrations.     

溶胶-凝胶法制备Li3V2 (PO4)3粉体的形貌控制研究

以LiOH·H2O,NH4VO3,H3PO4和柠檬酸为原料,十二烷基苯磺酸钠(SDBS)为表面活性剂,采用溶胶凝胶法实现了Li3V2(PO4)3粉体的制备.添加不同剂量的十二烷基苯磺酸钠(SDBS)探究其对Li3V2(PO4)3粉体物相形貌的控制作用,采用热分析、X射线衍射和场发射扫描电子显微镜对其晶型结构,形貌特征进行表征,从而研究Li3V2(PO4)3的合成温度及十二烷基苯磺酸钠(SDBS)加入量对粉体物相形貌的影响.结果表明,用溶胶凝胶法制备合成了单斜结构Li3V2(PO4)3粉体.SDBS的加入对样品的晶粒尺寸和表面形貌有一定的影响.     

循环爆破开挖下隧道围岩振动效应与损伤演化的模型实验

针对推进式循环爆破开挖下隧道围岩振动效应与损伤演化问题,按照相似比理论进行模型实验研究,实验模型采用1:15比例浇筑制成。通过模拟隧道推进式循环爆破开挖方式,以同一测点处爆破前后岩体声速变化评价隧道围岩损伤程度,探寻爆破参量变化对振动效应的影响,探索围岩损伤演化与爆破次数之间的关系。研究结果表明:在最大段药量大致相同情况下,起爆段数对萨道夫斯基公式的介质系数K影响很小,而对萨道夫斯基公式的衰减系数α影响较大;隧道在推进式循环爆破开挖下,同一深度距离爆区相同的测点,其声速降低率存在较大差异,围岩的爆破损伤范围在深度和广度方面均具有典型的各向异性特征;当爆炸参量基本相同时,不同循环爆破开挖下测点的累积声速降低率呈非线性增长趋势;在推进式循环爆破加载下,围岩爆破累积损伤量D与爆破次数n之间存在非线性演化特性,不同的测点具有各自的爆破累积损伤扩展模型,距离爆源越近爆破损伤扩展越快,围岩爆破累积损伤效应具有典型的非线性演化特性和各向异性特征。     

缅甸翡翠中锆石的LA-ICP-MS微量元素U-Pb年龄：对其成因的制约

翡翠产自与俯冲作用相关的HP/LT变质区域,对俯冲作用的研究具有重要意义。锆石常用来确定岩石的年龄,可以用于翡翠成因和形成时代的研究。缅甸是世界上优质翡翠最主要的产地,锆石是缅甸翡翠中常见的副矿物。选择含锆石较多的缅甸翡翠原石,对晶形较好的大颗粒锆石运用阴极发光(CL)图像观察锆石中颜色的分布和韵律环带形态的变化,并根据CL图像特征进一步采用激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)对锆石的微量元素和U-Pb年龄进行测定。结果表明具不同颜色和韵律环带形态的锆石,其微量元素分布有一定的差异,但总体却表现为：锆石的标准化球粒陨石稀土配分显示轻稀土元素(LREE)亏损,重稀土元素(HREE)富集,有明显的Ce(Ce/Ce*=19.2～74.2)正异常和微弱的Eu(Eu/Eu*=0.49～0.72)负异常。稀土元素总含量(∑REE)高(810～3 984 μg·g-1),(Yb/Sm)_N值为23.1～195.1(大部分值小于100);Th/U比值为0.28～1.18。研究锆石属于岩浆锆石,形成于俯冲带上覆地幔楔的镁铁质玄武岩浆之中,这类岩浆是陆下地幔橄榄岩受到俯冲过程中释放的流体作用部分熔融形成的。Ti温度计显示锆石的形成温度为762～923 ℃。锆石的206Pb/238U年龄为(157.3±1.3)Ma,这一年龄为锆石的形成时间。CL图像显示锆石中颜色的分布和韵律环带形态的变化与锆石的形成时间无关,是锆石中微量元素差异分布造成的,反映了锆石形成过程中岩浆熔体成分的动态演化。     

Influence of Cr on microstructure and elastocaloric effect in Ni–Mn–In–Co–Cr polycrystalline alloys

Ni–Mn-based metamagnetic shape memory alloys have been proposed as potential elastocaloric refrigerants. The intrinsic brittleness of the alloys has limited their cooling application. Introducing a soft second phase is an effective way to reduce the brittleness. From the viewpoint of application, the effect of second phase on elastocaloric effect should be illustrated. In this paper, we have investigated the microstructure, martensitic transformation and elastocaloric effect of Ni₄₅Mn_37-xIn₁₃Co₅Cr_x ($x=0,1\text{ and }2$) polycrystalline alloys. Single-phase and precipitates-containing microstructures are obtained for the undoped and doped alloys, respectively. The precipitates in Cr-doped alloys enhances the fracture strength but significantly hinders the martensitic transformation. Balancing the fracture strength and martensitic transformation, the Ni₄₅Mn₃₆In₁₃Co₅Cr alloy with small amount of precipitates along grain boundaries exhibits large cooling effects of 4–6 K in the temperature range of 317–353 K.     

有机阳离子对卤素钙钛矿太阳能电池性能的影响

采用第一性原理计算了CH_3NH_3PbI_3中有机部分CH_3NH_3~+和CH_3NH_3的静电特性.结果表明:CH_3NH_3~+具有强的亲电特性,CH_3NH_3的CH_3~-端具有弱亲电性,而NH_3~-端具有弱亲核性.发现在CH_3NH_3PbI_3中CH_3NH_3~+之间强静电排斥作用在相变中起着重要的作用,且在室温条件下CH_3NH_3~+在无机笼中具备活性和无序的特性,使得TiO_2/CH_3NH_3PbI_3异质结中n型TiO_2的电子通过界面扩散到CH_3NH_3PbI_3材料,并与CH_3NH_3~+结合形成CH_3NH_3,CH_3NH_3的静电特性导致在内建电场作用下更容易取向,取向的CH_3NH_3周围形成的静电场会变得更弱和更加均匀.这对无机框架上载流子的产生和传输更加有利,这样的异质结比传统的pn结具有更大优势.这是CH_3NH_3PbI_3太阳能电池高的光电转换效率的重要原因.     

绝缘体上硅金属氧化物半导体场效应晶体管中辐射导致的寄生效应研究

基于⁶⁰Co γ射线源研究了总剂量辐射对绝缘体上硅（silicon on insulator,SOI）金属氧化物半导体场效应晶体管器件的影响.通过对比不同尺寸器件的辐射响应,分析了导致辐照后器件性能退化的不同机制.实验表明：器件的性能退化来源于辐射增强的寄生效应;浅沟槽隔离（shallow trench isolation,STI）寄生晶体管的开启导致了关态漏电流随总剂量呈指数增加,直到达到饱和;STI氧化层的陷阱电荷共享导致了窄沟道器件的阈值电压漂移,而短沟道器件的阈值电压漂移则来自于背栅阈值耦合;在同一工艺下,尺寸较小的器件对总剂量效应更敏感.探讨了背栅和体区加负偏压对总剂量效应的影响,SOI器件背栅或体区的负偏压可以在一定程度上抑制辐射增强的寄生效应,从而改善辐照后器件的电学特性.