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关键词： 锰酸锂电池   分解反应   活化能   微观形貌  

摘要： 采用差热分析法研究了不同升温速率下锰酸锂前驱体所发生的分解反应,通过Kissinger法和Doyle Ozawa法对不同反应阶段的活化能进行计算,同时通过扫描电镜、粒度分析仪、X射线衍射仪对所得样品的微观形貌进行观察分析,结果表明,通过共沉淀法与煅烧法相结合制备所得LiMn_2O_4的物相纯净,粒度分布均匀,形貌规整。

关键词： 数学分析   函数   数学概念   做题方法  

摘要： 数学分析是数学专业本科阶段最重要的专业基础课程之一,该课程概念较多且较抽象,逻辑性强,同时各个知识点的关联性强。相当一部分的学生上课时,觉得该课程并不难,但一旦自己动手做题就常常出现无从下手。针对这些问题,文章将结合教学实践,提出一些该课程的学习方法和做习题的合理方法。

摘要： We consider the problem of small oscillations of a rotating inviscid incompressible fluid. From a mathematical point of view, new exact solutions to the two-dimensional Poincare-Sobolev equation in a class of domains including trapezoid are found in an explicit form and their main properties are described. These solutions correspond to the absolutely continuous spectrum of a linear operator that is associated with this system of equations. For specialists in Astrophysics and Geophysics, the existence of these solutions signifies the existence of some previously unknown type of inertial waves corresponding to the continuous spectrum of inertial oscillations. A fundamental distinction between monochromatic inertial waves and waves of the new type is shown: usual characteristics (frequency, amplitude, wave vector, dispersion relation, direction of energy propagation, and so on) are not applicable to the last. Main properties of these waves are described. In particular, it is proved that they are progressive. Main features of their energy transfer are described.

关键词： 提高   小学高年段   数学   分析能力  

摘要： 小学正是处于数学学习的启蒙阶段,特别是在小学高年段这一学习时期,教师应当把对学生数学思维的导入,逻辑步骤的把控,分析能力的提高,作为重点培养和研究的教学模块,这将为日后学生构建数学的学习体系,掌握数学的学习方法,有着重要的指导和现实意义。本文将通过对实际例题的解析,进而介绍对小学高年段数学题目的解题思路,从而实现提高学生数学分析能力的目的。

关键词： Virtual screening   Molecular dynamics   Histone deacetylases inhibitors  

摘要： Histone deacetylases (HDACs) family has been widely reported as an important class of enzyme targets for cancer therapy. Much effort has been made in discovery of novel scaffolds for HDACs inhibition besides existing hydroxamic acids, cyclic peptides, benzamides, and short-chain fatty acids. Herein we set up an in-silico protocol which not only could detect potential Zn2+ chelation bonds but also still adopted non-bonded model to be effective in discovery of Class I HDACs inhibitors, with little human's subjective visual judgment involved. We applied the protocol to screening of Chembridge database and selected out 7 scaffolds, 3 with probability of more than 99%. Biological assay results demonstrated that two of them exhibited HDAC-inhibitory activity and are thus considerable for structure modification to further improve their bio-activity. (C) 2017 Published by Elsevier Inc.

关键词： high electron mobility transistors   gallium compounds   wide band gap semiconductors   III-V semiconductors   mathematical analysis   invertors   mathematical analysis   HEMT false turn-on phenomenon   high-power density   power conversion systems   electric vehicles   power devices   circuit magnetic components   high-speed switching characteristics   power losses   radiation resistances   complementary device   three-phase full-bridge inverter   HEMT gate voltage   gate voltage spike   GaN  

摘要： High-power density is required in power conversion systems used in various applications, especially in electric vehicles. Driving the power devices with high frequency is one of the successful solutions to downsize a circuit's magnetic components, and hence an overall high-power density of the circuit can be realised. Therefore, GaN high electron mobility transistor (HEMT) is widely used in many applications, owing to its high-speed switching characteristics, low power losses, and high heat and radiation resistances. However, the high-speed switching of GaN HEMT comes with a drawback. For instance, in a full-bridge inverter configuration, high-speed turn-on of one device may cause a false turn-on of the complementary device. If a power device has encountered a false turn-on, the GaN HEMT devices will suffer from overcurrent, excessive heat and is eventually destructed due to the short circuit. This phenomenon can be tackled by modifying the circuit conditions. In this Letter, the theoretical analysis of a three-phase full-bridge inverter is developed to figure out the behaviour of the GaN HEMT gate voltage, which is the key-factor parameter causing a false turn-on. On the basis of the proposed theoretical analysis, the circuit conditions which minimise the gate voltage spike are derived.

关键词： 数学语言   命题   应用   数学分析   高等数学   定义  

摘要： 本文介绍数学分析中的Cauchy命题与ε语言，从本质上阐述它们之间的关系，以数学语言为主，图表为辅来描述两种方法的异同及应用。极限的ε语言定义是非常精准但又极其抽象的定义，它广泛地出现在高等数学的各个领域，本文只针对于ε语言与Cauchy命题的相关性展开讨论。

关键词： 数学分析   粮堆   自然对流   热量传递   水分迁移  

摘要： 本文基于仓储粮堆内部自然对流、热湿耦合传递的数学模型,采用数学分析的方法对模型中各个方程中的各项的物理意义和数量级大小进行了分析,探讨了仓储粮堆内部自然对流、热量传递和水分迁移过程的相互关系。提出了判断粮堆内部自然对流强弱的瑞利数及其影响因素,分析了仓型结构、粮种及仓外大气温度对粮堆内部自然对流、热量传递和水分迁移的影响,并通过数值模拟对数学分析结果进行了验证。结果表明,数学分析方法是分析仓储粮堆内部自然对流、热量传递和水分迁移过程的一种有效途径,数学分析的结果可以为仓型设计、储粮生态系统的模拟、仓储技术管理提供借鉴。

关键词： 煤炭开采   采煤机   自动化割煤   记忆割煤   单示范刀   双示范刀   运动坐标系  

摘要： 现有采煤机自动化割煤方法缺乏合适的数学模型及算法,无法实现长期、连续自动化割煤,制约了工作面自动化水平的提高。针对该问题,在三维坐标系中分析了采煤机姿态、位置与截割高度之间的函数关系,建立了基于静止坐标系和运动坐标系的采煤机运动方程,并提出了基于运动坐标系的双示范刀、单示范刀记忆割煤算法及具体实现方法。在锦界煤矿31112工作面应用单示范刀记忆割煤算法进行长期自动化割煤,实现了包括三角区在内的全工作面区域自动化割煤,证明了算法的正确性、可行性及鲁棒性。