电容温度传感器的实验研究

从液氮温度到水的沸点温度范围内,测量了介质分别为钽,涤纶,陶瓷,玻璃釉和陶瓷独石一体化结构的商用固体电容器的电容量-温度之间的关系.拟合测量结果表明,独石陶瓷电容器在正温度段具有较好的线性响应(-10pF/℃),灵敏度(0.1 ℃)和精确度(标准差为0.016);而涤纶电容器在负温度段的特性较好( 17pF/℃,0.06 ℃和0.01).此外,在约0.5特斯拉的恒定磁场作用下,无论在正或负温度段,上述测得的电容量-温度关系几乎不受影响.因此,本研究对开发抗强电磁场,自加热效应小或导热系数小的低温测温器具有较大的参考价值.     

中国建筑产业链两阶段综合效率、纯技术效率、规模效率及其影响因素

目前从建筑产业链角度对建筑产业效率问题的研究并不多。据此,本研究通过梳理相关文献,识别出建筑产业链的两个关键环节:工程咨询阶段和工程施工阶段;根据筛选的建筑产业链投入、产出指标,利用链式关联网络DEA模型测算2014~2015年中国各省份建筑产业链两阶段的综合效率、纯技术效率与规模效率;利用Tobit模型确定影响三种效率的关键因素,以此实现对建筑产业链两阶段生产资源的优化与整合,更期待为客观度量产业链两阶段生产效率的研究提供新思路与方法。研究发现,综合效率普遍偏低且各省份之间差距较大,其主要原因是纯技术效率偏低且省份之间差异大;三种效率的主要影响因素及其作用程度不尽相同。在此基础上提出相应的对策建议以促进中国建筑业生产效率的提高。     

Modeling,simulations,and optimizations of gallium oxide on gallium-nitride Schottky barrier diodes

With technology computer-aided design(TCAD)simulation software,we design a new structure of gallium oxide on gallium-nitride Schottky barrier diode(SBD).The parameters of gallium oxide are defined as new material parameters in the material library,and the SBD turn-on and breakdown behavior are simulated.The simulation results reveal that this new structure has a larger turn-on current than Ga2O3 SBD and a larger breakdown voltage than Ga N SBD.Also,to solve the lattice mismatch problem in the real epitaxy,we add a Zn O layer as a transition layer.The simulations show that the device still has good properties after adding this layer.     

A boundary Schwarz lemma for pluriharmonic mappings from the unit polydisk to the unit ball

In this article, we present a Schwarz lemma at the boundary for pluriharmonic mappings from the unit polydisk to the unit ball, which generalizes classical Schwarz lemma for bounded harmonic functions to higher dimensions. It is proved that if the pluriharmonic mapping f ∈ P(D~n, B~N) is C~(1+α) at z0 ∈ E_rD~n with f(0) = 0 and f(z_0) = ω_0∈B~N for any n,N ≥ 1, then there exist a nonnegative vector λ_f =(λ_1,0,…,λ_r,0,…,0)~T∈R~(2 n)satisfying λ_i≥1/(2~(2 n-1)) for 1 ≤ i ≤ r such that where z'_0 and w'_0 are real versions of z_0 and w_0, respectively.     

BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂的制备及光催化性能研究

以Bi(NO_3)_3·5H_2O和NH_4VO_3为原料,控制水溶液介质p H及反应时间,采用水热合成法制备钒酸铋(BiVO_4)及其复合物(BiVO_4/Bi_6O_6(OH)_3(NO_3)_3).利用X-射线粉末衍射、扫描电子显微镜和紫外-可见漫反射吸收光谱等手段对制备的样品进行了物理表征,结果表明,在控制反应时间为1 h,介质p H值在1.14~9.01之间时,制备的样品为BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合物,当p H值增加至10.92时为纯BiVO_4;控制介质p H为7.17,反应时间在1~12 h之间时得到BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂,反应时间为18 h时为纯BiVO_4.在可见光(λ≥400 nm)照射下,以有机染料罗丹明B(Rhodamine B,Rh B)为底物,研究不同条件制备的BiVO_4或者复合物为光催化剂的光催化特性,发现p H=7.17,水热反应12 h得到的催化剂(BiVO_4/Bi_6O_6(OH)_3(NO_3)_3)光催化降解活性高于对照制备的纯BiVO_4.同时在可见光照射下,BiVO_4/Bi_6O_6(OH)_3(NO_3)_3亦可以有效降解无色小分子2,4-二氯苯酚(2,4-Dichlorophenol,2,4-DCP),说明氧化过程涉及到光催化过程.分析BiVO_4/Bi_6O_6(OH)_3(NO_3)_3复合光催化剂对Rh B光催化降解过程中活性物种,表明在降解过程中主要涉及空穴和超氧氧化,O_2·~-起主要作用.     

电解质材料Sr-和Mg-掺杂LaGaO3的制备及性能研究

A dense La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 electrolyte in pure perovskite phase was prepared by a polyacrylic acid assisted solid state reaction method, and the effects of La source on the structure and electrochemical performance were also studied. By means of XRD and SEM, the structure of this material was characterized, and the electrochemical properties were studied through AC impedance diagram. The results show that the sample presents a single perovskite-type phase after sintering at 1 450 ℃ and the relative density is 94%. The specimen has the lower activate energy and higher electrical conductivity at 600 ℃. There are two different activation energy at the turning point of 650 ℃, which are 74.6 and 42.4 kJ·mol^-1, respectively. The electrical conductivity is 0.057 S·cm^-1 and 0.017 S·cm^-1 at the temperature of 800 ℃ and 600 ℃, respectively.