Analysis of Density Wave Oscillations in Helically Coiled Tube Once-Through Steam Generator

螺旋管式直流蒸汽发生器(H-OTSG)具有传热性能良好、布置紧凑、热膨胀自由等优势，在先进小型模块化反应堆(SMR)以及其他工业换热设备中获得了广泛的应用。在特定的工况中，螺旋管式直流蒸汽发生器可能发生流动不稳定性现象，一旦发生，将严重危及反应堆安全。为了确保反应堆的安全性，必须对蒸汽发生器内的流动不稳定现象进行分析，避免流动不稳定现象的产生。 目前的蒸汽发生器流动不稳定性程序大多针对直管或U型管，缺少针对螺旋管开发的流动不稳定性分析工具。在这些程序的计算中，往往考虑均匀热流边界条件，而忽略了真实换热过程中出现的非均匀热流边界条件。为了更准确地研究螺旋管式蒸汽发生器的流动不稳定性问题，需要针...Helically coiled tube Once-Through Steam Generator (H-OTSG) is widely adopted in advanced small modular reactors (SMR) and other industrial heat exchange equipment for its compactness, enhanced heat transfer efficiency and capability of accommodating thermal expansion. Under certain working conditions, two phase flow instability that endangers safety of plants can occur in the secondary side of H-...学位：工学硕士院系专业：能源学院_核工程与材料学号：3242014115222

Modeling and Simulation for PWR Rressurizer Based on Modelica

稳压器是压水堆核电站的重要设备之一。使用面向对象的建模工具Modelica/Open Modelica仿真软件对稳压器进行新模型的开发,并将模型仿真结果与希平港核电站减负荷试验结果进行比较,验证新建模型的有效性,可为核电站其它系统设备的建模仿真的应用提供参考。Modelica语言对象导向的特性为核电站系统设备全生命周期的模型开发实现继承和延伸管理。Pressurizer is one of the important equipment in the pressurized water reactor nuclear power plant. Using oriented object modeling tool Modelica/Open Modelica simulation software, the new model of Presssurizer was developed, and simulation results and Shippingport nuclear power plant loss load test results were compared and the validity of the new model was verified. It can provide a reference for the application of the modeling and simulation of other system and equipment in the nuclear power plant. Modelica language object oriented characteristics can achieve the inheritance and extension management of nuclear power plant system and equipment modeling development for the whole life cycle

基于生态砖构建的新型河堤结构及位移分析

结合生态治理的要求,在分析国内外生态河堤的发展状况及相关的优缺点的基础上,提出了新型生态河堤,并通过ANSYS有限元软件对生态河堤的承载力及刚度进行有限元分析,对局部河堤结构进行了试验探究,并将有限元结果与试验结果进行对比,吻合情况较好。同时有限元结果也表明结构有较好的承载力、刚度、稳定性以及生态效果等,真正达到了人与自然的关系的和谐

Musical Expertise and Melodic Structure in Memory for Musical Notation

Two experiments plus a pilot investigated the role of melodic structure on short-term memory for musical notation by musicians and nonmusicians. In the pilot experiment, visually similar melodies that had been rated as either good or bad were presented briefly, followed by a 15-sec retention interval and then recall. Musicians remembered good melodies better than they remembered bad ones: nonmusicians did not distinguish between them. In the second experiment, good, bad, and random melodies were briefly presented, followed by immediate recall. The advantage of musicians over nonmusicians decreased as the melody type progressed from good to bad to random. In the third experiment, musicians and nonmusicians divided the stimulus melodies into groups. For each melody, the consistency of grouping was correlated with memory performance in the first two experiments. Evidence was found for use of musical groupings by musicians and for use of a simple visual strategy by nonmusicians. The nature of these musical groupings and how they may be learned are considered. The relation of this work to other studies of comprehension of symbolic diagrams is also discussed

The effect of nurse initiated patient/family education strategy on people with schizophrenia in Beijing

2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Design of Controller for Polynomial Nonlinear Systems Based on SOS

现实生活中的控制系统几乎都是非线性控制系统，对于一般的非线性系统，人们常采取的策略是通过各种变换思想把复杂的非线性系统转化为线性系统，再利用线性系统控制理论设计出合理的控制器。这种控制思想可满足精度要求不高、复杂度不高的非线性系统，但无法满足现代工业中存在的具有高精度要求的复杂非线性系统。 随着现代微分几何理论的发展，非线性系统控制理论也取得了较快发展，很多好的非线性控制思想被提出，为解决非线性控制问题提供了理论依据。作为非线性系统的一类主要研究对象——多项式非线性系统，一直以来是个热门问题，受到了很多学者的青睐。近年来，自SOS理论被提出后，更多学者加入多项式非线性控制系统研究领域。学者们...Almost all real-life control systems are nonlinear. People usually adopt the strategy to simplify the complex nonlinear system into the linear system by using the nonlinear transformation as well as nonlinear feedback, thus the linear control theory is applicable. Nevertheless, the linear control theory is effective only for the systems with simple structures or with the requirements at low levels...学位：工学硕士院系专业：信息科学与技术学院自动化系_控制理论与控制工程学号：2322008115334

高速动车组驱动齿轮箱的约束模态分析与结构改进

以某高速动车组驱动齿轮箱为研究对象，采用APDL语言建立齿轮箱约束模态分析参数化模型，应用弹簧单元模拟轴与箱体之间的结合面，通过有限元分析得到齿轮箱前4阶约束模态振型及其固有频率；运用Sobol局部灵敏度分析方法，确定影响齿轮箱固有频率的关键结构参数，分析关键结构参数对固有频率的影响规律；在此基础上，对关键结构的尺寸参数做出改进，使齿轮箱的1阶、2阶固有频率提高了5%以上，提高了齿轮箱的抗振能力。为高速动车组驱动齿轮箱的改进设计提供了理论依据

房间里的大象:有关行为成瘾的争议及回应

ICD-11设立行为成瘾分类并将赌博障碍和游戏障碍归入其下,引发了学界的争议和大众的关切。本文述评了对于行为成瘾分类的争议和相关回应,包括将过度的赌博行为和游戏行为作为精神障碍是否合理、两类行为模式是否确实是成瘾障碍、诊断标准是否合适、此举是否产生负面影响等问题,以期明确行为成瘾分类的合理性和必要性,并为当前蓬勃发展的行为成瘾研究及临床实践提供参考。</p

Mineral N accumulation and distribution of apple orchard soil on the Weibei dryland

对渭北旱塬6~37龄苹果园土壤剖面中硝态氮和铵态氮的含量进行了分析测定,以了解不同树龄,不同剖面深度土壤矿质氮累积与分布状况。结果表明,不同种植年限苹果园0~400 cm剖面土体中,氨态氮的含量和分布保持相对稳定;硝态氮含量和分布变化显著,含量在0.31~195.32 mg/kg之间,土体剖面硝态氮的累积量呈显著增加的趋势,累积层出现在40~260 cm土层,最高含量出现在15龄果园的100~120 cm土层中,其值为195.32 mg/kg。土壤剖面累积大量的硝态氮,可能会造成潜在的环境问题