Combining GPS carrier phase and Doppler observations for precise velocity determination

The truncation error and propagation error are analyzed for velocity determination through differential GPS carrier phase observations,and an approach for the choice of the best number of points for the central difference method is developed.In order to overcome the disadvantages of existing GPS velocity determination methods,a new velocity determination algorithm is presented,based on combining carrier phase and Doppler observations.The basic idea is that two types of observation are combined by adding the...     

Syntheses and Crystal Structures of Two One-dimensional Cobalt(Ⅱ) Compounds with the Flexible Dipyridyl Ligan

Two one-dimensional cobalt(Ⅱ) compounds {[Co(Hbpma)(H2O)4 ] 2 ·3SO 4 ·4.5H2O} n1 and {[Co(Hbpma)(NCS) 3 (H2O)]·2.85H2O}n2 (bpma = N,N -bis(3-pyridylmethyl)amine) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 15.8780(5), b = 16.2187(5), c = 16.4858(5) , α = 91.0420(10), β = 94.5190(10), γ = 101.4360(10)°, V = 4145.7(2) 3 , C 24 H 53 Co 2 N 6 O 24.50 S 3 , M r = 1031.76, Z = 4, D c = 1.653 g/cm 3 , μ(MoKα) = 1.046 mm -1 , F(000) = 2148, S = 1.017, the final R = 0.0269 and wR = 0.0644 for 13032 observed reflections (I > 2σ(I)). For complex 2, it belongs to triclinic, space group P1 with a = 9.3761(11), b = 10.5814(13), c = 11.2972(14) , α = 85.472(2), β = 88.058(2), γ = 76.203(2)°, V = 1085.0(2) 3 , C 15 H 21.70 CoN 6 O 3.85 S 3 , M r = 502.79, Z = 2, D c = 1.539 g/cm 3 , μ(MoKα) = 1.112 mm -1 , F(000) = 519, S = 1.070, the final R = 0.0358 and wR = 0.0899 for 3466 observed reflections (I > 2σ(I)). Two complexes 1 and 2 are both found to be one-dimensional coordination polymers bridged by the protonated bpma ligands, which are assembled into three-dimensional supramolecular structures through the hydrogen bonding interactions and π-π packing interactions.     

Chemical synthesis and characterization of manganese oxide coated Ni particles

Nanosized Ni particles with an average diameter of about 8 nm were prepared by reducing of NiCl 2 with sodium borohydride (NaBH 4 ) in aqueous solution. By moderate annealing in protective atmosphere, the composite grew up to be 15-20 nm particles. Both of the as-prepared and annealed Ni particles were coated by a layer of manganese oxide via decomposition reaction in aqueous KMnO4 solution. Hysteresis loops of as-prepared samples show a large increase in the magnetization with decreasing temperature and an unsaturated component at high magnetic field. In contrast, the ferromagnetic characteristics of annealed one are much stronger with large magnetization and coercivity. The thermomagnetic curves verified the coexistence of ferromagnetic Ni and antiferromangetic Mn oxide phases. But there exists no exchange bias behavior in the samples, even though the interface structure between the ferromagnetic Ni core and the antiferromagnetic manganese oxides has been distinctly formed. The absence of exchange bias probably originates from the weak ferromagnetic characteristic of Ni cores.     

利用手持技术探究加热过程中石棉网上表面的温度

利用手持技术实时精确测量加热中石棉网上表面不同位置的温度，采用独立样本t检验比较石棉网上表面无铁丝点和有铁丝点间的温度差异与温差差异，通过回归分析探究石棉网上表面温度与其主要影响因素间的关系。研究表明：同等条件下加热中的石棉网上表面无铁丝点与有铁丝点存在显著温度差异，而无铁丝点间的单位距离温差与有铁丝点间的单位距离温差无显著差异；石棉网升温阶段上表面温度与时间、位置的关系可拟合为二元一次线性方程，恒温阶段上表面温度与位置的关系可拟合为一元三次曲线方程；石棉网上表面温度从中心向边缘小幅递减，均匀分布，最大温差小于玻璃仪器的耐热骤变温差。研究结果为化学教育实践中科学使用石棉网以及化学实验教材的编写提供参考依据。     

基于B样条的TERS形貌成像背景扣除方法

在针尖增强拉曼光谱(TERS)形貌成像过程中，由于针尖与扫描台无法绝对平行、样品电子密度骤变处针尖快速升降以及扫描控制系统响应时间特性差等综合原因的影响，往往使形貌图中带有倾斜或边界面卷曲的成像背景。成像背景对样品形貌的识别和分析带来十分不利的影响，而背景扣除就是解决该问题的重要手段，也是形貌成像预处理的重要组成部分。背景扣除的原理一般是通过拟合背景的方法来扣除成像中的背景。传统的背景扣除方法是利用多项式拟合的方法对成像进行逐行的基线校正，但是该方法在处理形貌成像时常常会由于过拟合而造成样品形貌的失真，同时容易在图片上留下明显的线条纹理。针对传统方法的缺点，本文提出采用B样条曲面拟合方法，直接对样品形貌图进行曲面背景拟合，发挥B样条低阶光滑的优点，能够有效克服传统方法的缺陷。在实验中，同时利用传统方法和该方法对金单晶和合成金片的形貌图进行背景扣除，实验结果表明，两种方法都能够扣除样品形貌图中的成像背景，但与传统方法相比，所提出的方法不会造成样品形貌的失真，且不会留下线条纹理，获得了更加良好的背景扣除效果，为进一步分析样品形貌特征提供了更准确可靠的信息，是一种更加有效的TERS形貌成像背景扣除算法。     

Extinction Effects of Multiplicative Non-Gaussian L′evy Noise in a Tumor Growth System with Immunization

The extinction phenomenon induced by multiplicative non-Gaussian Levy noise in a tumor growth model with immune response is discussed. Under the influence of the stochastic immune rate, the model is analyzed in terms of a stochastic differential equation with multiplicative noise. By means of the theory of the infinitesimal generator of Hunt processes, the escape probability, which is used to measure the noise-induced extinction probability of tumor cells, is explicitly expressed as a function of initial tumor cell density, stability index and noise intensity. Based on the numerical calculations, it is found that for different initial densities of tumor cells, noise parameters play opposite roles on the escape probability. The optimally selected values of the multiplicative noise intensity and the stability index are found to maximize the escape probability.     

基于油藏实际的稠油层内水热催化裂解机理研究

开展了稠油层内水热催化裂解技术在胜利油田的先导实验,五口井平均周期单井增油653 t,稠油初期降黏率达79.8%,措施14周后降黏率仍大于62%。利用Brookfield DV-Ⅲ黏度计、ElementarVario EL III元素分析仪、Knauer K-700蒸气压渗透仪、Agilent 6890N气相色谱仪和EQUINOX 55傅里叶变换红外光谱仪等,对措施前后稠油的物化性质进行分析。结果表明,层内水热催化裂解后稠油黏度及平均分子量减小、轻烃含量增加、重质组分含量减少、氢碳原子比增加、杂原子含量减小。稠油层内裂解反应受催化剂体系、高温水及储层矿物因素控制,催化剂是促进稠油裂解的主要因素,供氢剂及分散剂等助剂有助于提高裂解效果,高温水的酸碱性质及储层矿物对稠油具有催化裂解作用。多因素协同作用下使稠油发生脱侧链、分子链异构、断链、加氢、开环、成环、脱硫等系列反应,使得稠油大分子分解成小分子物质,降低了稠油黏度,改善了稠油品质,证实该技术在现场应用中具有可行性。     

nc-Ge/SiN_x多层膜的光致发光特性

通过将a-Ge∶H/a-SiN_x多层膜进行氧化,制备了nc-Ge/SiN_x多层膜。观察到了室温下的强烈可见光发射,发光波长为500nm。通过分析,排除了与量子限制效应有关的光发射机制,也排除了与Si和N相关的缺陷产生的复合机制,认为该发光源于氧化后的a-SiN_x介质层中带尾态之间的辐射复合,最有效的激发能量约为介质层的带隙。     

一系列萘羧酸膦酸镧系配合物的合成、结构和荧光性质

在溶剂热条件下，5-羧酸-1-萘膦酸（5-pncH₃）和稀土硝酸盐反应合成得到3例萘羧酸膦酸镧系配合物：[Pr （5-pnc）（H₂O）]·2H₂O （1）、[Sm （5-pnc）（H₂O）]·H₂O （2）和[Eu （5-pnc）（H₂O）]·H₂O （3）。采用单晶X射线衍射、粉末X射线衍射、元素分析、红外光谱、热重分析和荧光光谱对配合物进行了表征。晶体结构表明，每个七配位的镧系离子由来自5个膦酸盐配体的6个O原子和来自1个配位水分子的一个O原子配位。[LnO₇]通过O—C—O、O—P—O或—O—单元连接成一维双金属链结构，一维双金属链再进一步由萘羧酸膦酸配体（5-pnc^3-）连接成三维开放骨架结构。荧光性质研究表明，配合物3在330 nm的激发光下，发射Eu的红色特征荧光，而配合物1和2在蓝光区显示出非常宽的配体中心发射带。     

卤化钙钛矿太阳能电池材料理论研究进展

卤化钙钛矿由于具有低成本、高效率等特点,最近作为非常有前景的太阳能电池吸收层材料被广泛研究。卤化钙钛矿型太阳能电池效率在短短的几年间由3.8%(2009年)迅速增加到22.1%(2016年)。卤化钙钛矿型太阳能电池的出现彻底改变了太阳能电池领域,不仅因为它们快速增长的效率,而且因为它们在材料生长和结构方面的可控性。卤化钙钛矿型太阳能电池的优越性能说明卤化钙钛矿材料具有独特的物理性质。在本综述中,我们总结了卤化钙钛矿材料最近几年在结构、电学、光学方面的理论研究成果,这些都与它们在太阳能电池方面的应用密切相关。我们也将探讨一些卤化钙钛矿型太阳能电池目前遇到的挑战以及可能的理论解决途径。