NaY（WO4）2:Eu3+红色荧光粉的水热法制备及其发光性能研究

采用水热法,在乙二醇:水=1:4的环境下制备出了NaY(WO4)2:Eu3+红色荧光粉,研究了体系pH值对粉体结构、形貌以及发光性能的影响.采用X-射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、荧光分光光度计(PL)对样品进行了表征.结果表明:在180℃下可以得到纯相结构的NaY(WO4)2:Eu3+荧光粉,反应体系的pH值对合成的粉体的形貌及发光性能有显著影响.     

基于CFD的螺旋槽干气密封端面开孔流场的分析

为了测量静环端面安装传感器开孔对流场气膜压力的影响因子,应用Solidworks软件建立三维螺旋槽干气密封端面气膜模型,包括在动环槽底根径相对的静环端面开孔和不开孔的2种模型建模.在特定工况下,运用Fluent软件对螺旋槽干气密封内部微间隙三维气体流场2种模型以层流模式分别进行数值模拟,得到2种模型的泄漏量,且与试验值...     

一类离散非自治捕食模型持久性与周期解的存在性

主要讨论一类具有Ⅳ类功能反应的离散非自治捕食模型,利用比较原理和重合度理论,获得了其持久性和周期解的存在性的充分条件.     

多级热处理对TC21钛合金组织和力学性能的影响

Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in the α + β region (940°C) with furnace cooling (FC), air cooling (AC), and water cooling (WC), followed by a second-stage solution treatment at a lower temperature in the α + β region (900°C), and then finally aged at 590°C. The effects of the morphology and quantity of α phases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed. The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy (SEM). The quantity of equiaxed α phases as well as the thickness of lamellar α phases reduced, the tensile strength increased firstly and then decreased, the elongation decreased with the increasing cooling rate after the first-stage solution treatment. The amount and size of lamellar α phases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements, thereby leading to increased tensile strength. The amount of dispersed α phases increased after the third-stage aging treatment owing to the increase in the nucleation rate, resulting in a noteworthy strengthening effect. After the third-stage aging treatment, the first-stage FC sample exhibited better mechanical properties because it contained more equiaxed α and β_trans phases than the first-stage AC and WC samples.     

抑制学生随意评教的方法研究

学生评教虽然可以有效地衡量高校教学质量,但是必须在保证评教体系的可信度的前提下,抑制掉学生评价的随意评教数据,才能提高测评数据的有效性,否则学生评教将毫无意义。在分析历史测评数据的基础上,重点研究了学生随意评教数据的特点及其抑制的方法。     

无机盐作用下伊利石水化特性的分子模拟

伊蒙混层水化导致井壁失稳的现象相当突出，蒙脱石的水化研究较多。为研究伊利石在无机盐作用下的水化机理及膨胀特性，通过分子模拟技术建立了1M-tv和1M-cv两种在油气储层中较常见的伊利石晶体模型，并进一步通过分子动力学方法研究了伊利石层间粒子的微观分布和进入层间的无机盐阳离子的水化参数。结果表明，伊利石层间距随吸附水分子数的增大而增大，当水分子数为20时达到饱和状态； 1M-tv构型比1M-cv构型更容易发生水化膨胀； K⁺和Ca²⁺分别是一价阳离子和二价阳离子中水化数和水化半径最小的，且K⁺可以嵌入四面体片层的硅氧六元环中而难以发生离子交换，可有效阻止水分子进入伊利石晶体结构内部；实验结果很好地验证了KCl和CaCl₂对伊利石水化膨胀的抑制性。该结果对于页岩的防塌机理研究和钻井液水化抑制剂的研究具有一定的理论指导意义。     

江西省万年县乡村地域多功能时空特征与格局演化

以江西省万年县128个行政村为研究对象, 2010—2018年为研究时点, 从生产功能、生活功能和生态功能3个维度, 构建乡村地域多功能评价指标体系, 定量地测度乡村地域各项功能强度, 通过趋势面分析、空间自相关和冷热点分析等方法, 系统地剖析和刻画万年县乡村地域各项功能强度的时间变化和空间分异过程。结果表明, 2010—2018年万年县乡村地域各项功能指数的时间差异和空间分异特征明显, 局部集聚效应显著, 但整体上区域差异缩小。未来应引导区域乡村分类发展, 提升其主导功能, 实现乡村可持续发展。     

红枣中γ-氨基丁酸的研究进展

氨基丁酸(GABA)是一种非蛋白氨基酸,它广泛分布于微生物、动物和植物体内,具有降血压、改善记忆、抑制癌细胞增殖、增强免疫、减少失眠等功效。阐述了红枣改善睡眠的研究进展,介绍了红枣中GABA的发现,探讨了GABA的测定方法。通过红枣改善睡眠的文献分析,推测红枣中可能含有GABA,然后结合初步调研结果,证实红枣中含有GABA,并且发现每日食用61g干制骏枣(约3颗),能够获得足够的GABA,从而达到改善睡眠的功效,说明GABA可能是红枣中重要的功能成分；再对GABA含量测定的现有方法的优缺点进行了分析,并提出有必要开展邻苯二甲醛柱前衍生HPLC法分析GABA含量的条件优化的对策；最后,对红枣GABA未来研究方向进行了展望,为今后深入研究红枣中GABA提供理论参考。     

A resource-fair protocol for two-party coin toss

Coin-flipping protocols allow mutually distrustful parties to generate a random bit with uniform distribution.Minimizing bias and keeping fairness are two key requirements in designing such protocols.However,the best previously known fair coin-flipping protocol only guarantees with bias Ο(1 /r).In the paper,we introduce a new approach for fair coin-flipping protocol construction by using Garay et al’s "resource fairness" technique and propose a resource-fair two-party coin-flipping protocol according to the standard real/ideal simulation paradigm.Compared with the other coin-flipping protocols,our protocol enjoys an important advantage that its bias is 0.     

The uncertainty measure for q-exponential distribution function

Based on the q-exponential distribution which has been observed in more and more physical systems, the uncertainty measure of such an abnormal distribution can be derived by employing a variational relationship which can be traced from the first and second thermodynamic laws. The uncertainty measure obtained here can be considered as the entropic form for the abnormal physical systems having observable q-exponential distribution. This entropy will tend to the Boltzmann-Gibbs entropy when the nonextensive parameter tends to unity. It is very important to find that this entropic form is always concave and the systemic entropy is maximizable.