关键词： 三峡水库   重庆两江   水环境模型   汇流比   变动回水区  

摘要： 模拟和预测环境流体中物质的混合和输运过程是环境管理中的一个重要环节。河流的动力特点和物质输运能力直接关系到河流的自净能力。三峡水库建成后,重庆主城区河段处于水库变动回水区的中上段,其水动力条件和物质输运能力将发生巨大变化。本文主要内容是针对重庆主城区河段的水环境管理、城市防洪和饮用水的采集等实际问题进行了环境流体动力学研究,这对于三峡工程的环境安全也是极为重要的研究,并且为三峡库区水环境的研究提供了一个有力的服务工具。因而本研究具有重要的科学意义和实际意义。 本文工作主要以长江、嘉陵江重庆河段的水环境动力研究为目的,针对这类山区河流地形变化剧烈,水位涨落大,流速变化大的特点,建立相应的三维非定常流数值模型,并利用该模型研究重庆水环境变化的规律。前三章的内容是河流数值模拟的理论部分,后三章内容是数值模型在河流研究中的应用,包括西江航道整治的研究、重庆两江汇流段水动力的研究和重庆主城区河段水环境的研究。在前两个模型的成功应用的基础上,本文建立了重庆主城区河段模型并成功应用于模拟重庆两江河段的流场、浓度场和漂浮物运动。 第一章提出本文工作的目的和方法,论述河流数值模拟的难点和回顾有关研究现状。 第二章讨论浅水流理论和水质模型。浅水波假设符合大多数河流问题,其理论主要有Airy理论和Boussinesq理论两类。稳定而精度高的数值方法可以较为真实地反映物理现象和过程。应用有限体积法,建立了河流水质模型-嘉陵江石门段水质模型并完成了水质模拟。 第三章建立了一个三维非定常流的河流数值模型。水平面采用正交贴体网格,垂向采用σ坐标,引进了静水压近似和Boussinesq近似后,采用内外模式分裂法求解动量方程和连续方程,耦合求解流场和浓度场,紊动模型采用Mellor-Yamada模型。在数据的处理上,模型建立了专门的可视化软件。 第四章建立了西江四滩的悬浮物模型并应用于该河段的航道整治工程结果的预测。西江悬浮物模型模拟了复杂边界条件下的非定常水沙运动,以及河床冲淤过程。模拟的结果体现了模型在地形复杂,水流多变的河流研究中的应用能力,表明模型适用于处理运动边界、动床边界和悬沙运动,适于模拟弯道环流、绕流等流态。西江模型的建立和应用可以为动力条件相似的重庆河段的研究打下了基础。 第五章针对重庆河段复杂的两江汇流问题,建立两江汇流段水动力模型。模

关键词： 环境问题   超临界流体技术   绿色技术   能源   国际会议   天津大学  

摘要： 近日，在天津大学出席超临界流体技术国际会议的海内外专家指出，被称为“超级绿色技术”的超临界流体技术已成为解决能源与环境问题的关键技术。

关键词： 超临界流体技术   第三届   能源   环境   国际会议  

摘要： 第三届超临界流体技术用于能源与环境国际会议(The 3rd International Symposium on Supercritical Fluid Technology for Energy and Environment Application)于2004年10月23～26日在天津大学召开。本界会议由天津大学和中国化工学会化学工程专业委员会主办，

关键词： mixing   chaos   Lyapunov exponent   Poincare section   island   KAM boundaries   stretching of interface   Book   Thesis  

摘要： Periodic and chaotic dynamical systems follow deterministic equations such as Newton’s laws of motion. To distinguish the difference between two systems, the initial conditions have an important role. Chaotic behaviors or dynamics are characterized by sensitivity to initial conditions. Mathematically, a chaotic system is defined as a system very sensitive to initial conditions. A small difference in initial conditions causes unpredictability in the final outcome. If error is measured from the initial state, the relative error grows exponentially. Prediction becomes impossible and finally, chaotic systems can come to become stochastic system. To make chaotic motion, the number of variables in the system should be above three and there should be non-linear terms coupling several of the variables in the equation of motion. Phase space is defined as the space spanned by the coordinate and velocity vectors. In our case, mixing zone is phase space. With the above characteristics - the initial condition sensitivity of a chaotic system, our plan is to find most efficient chaotic stirrer. In this thesis, we present four methods to measure mixing state based on the chaotic dynamics theory. The Lyapunov exponent is a measure of the sensitivity to initial conditions and can be used to calculate chaotic strength. We can decide the chaotic state with one real number and measure efficiency of the chaotic mixer and find the optimum frequency. The Poincare section method provides a means for viewing the phase space diagram so that the motion is observed periodically. To do this, the trajectory is sectioned at regular intervals. With the Poincare section method, we can find ’islands’ considered as bad mixed zones so that the mixing state can be measured qualitatively. With the chaotic dynamics theory, the initial length of the interface can grow exponentially in a chaotic system. We will show the above characteristics of the chaotic system to prove as fact that our model is an e

关键词： 疏水   数字化微注射   微流体系统   玻璃微针   超微量   量可控  

摘要： 在生物医学和微化学分析领域 ,基于玻璃微针的微注射系统由于玻璃基质的亲水性 ,在微注射过程中会出现渗流、回流的现象 ,影响注射效果 ,不利于微注射量的检测和控制 .本文介绍的疏水化工艺通过将微喷嘴(微针 )内外表面特定区域进行疏水化处理 ,对微流体进行数字化驱动和控制 ,可改善微流体流动特性 ,提高微注射效果 ,使液滴按一定规律以球形颗粒喷射 ,有助于微流量的精确检测和微喷射的精确量可控 .

关键词： Coal   Redox reactions   Reaction products   Minerals   Biopolymers  

摘要： Tire rubber use in energy generation allows both to get cheaper energy and to eliminate a nonbiodegradable solid residue. Previously, to be established as a common practice in energy generation, its environmental impact must be assessed to ensure a sustainable development. With this aim, rubber from tire and 10/90 and 30/70 tire rubber/coal blends have been burnt in an atmospheric fluidized-bed reactor at different temperatures (750, 800, and 850 degreesC), keeping the gas speed (0.24 m/s) and the oxygen excess (5%) constant. The environmental impact on soil, water, and air because of the rubber from discarded tire combustion is deeply studied in this work. The disposal and lixiviation of the generated bottom ash as well as the atmospheric emissions in fly ash are analyzed by proximate and ultimate analysis, scanning electron microscopy, X-ray diffraction, inductively coupled plasma optical emission spectroscopy, and gas chromatography/mass spectrometry/mass spectrometry.

关键词： .microfluidic   holographic   Optical trapping   sorting   diode laser bar  

摘要： We demonstrate a new technique for trapping, sorting, and manipulating cells and micrometer-sized particles within microfluidic systems, using a diode laser bar. This approach overcomes the scaling limitations of conventional scanned laser traps, while avoiding the computational and optical complexity inherent to holographic optical trapping schemes. The diode laser bar enables us to control a large trapping zone, 1 mum by 100 mum, without the necessity of scanning or altering the phase of the beam. (C) 2004 Optical Society of America.

关键词： 天水强震区   深部构造   地下热流体  

摘要： 通过与肯尼亚Gregory地堑的深部构造的对比分析,本文研究了天水强震区深部发震环境的形成演化过程及其主要特征,探讨了深部热流体上涌在该地区深部发震环境形成演化过程中所起的重要作用,为进一步研究该地区前兆形成机理打下基础。

关键词： 地震   环境   地震学   地震计   地下   地震台   地震测量   规范   流体  

标准号: GB/T 19531.4-2004

摘要： 本部分规定了地震台站地下流体观测环境的技术指标、各类干扰源距观测井(泉)的最小距离及基相关的测试与计算方法。 本部分适用于各类地震台站地下流体观测环境的评估、管理与保护及新建台站的选址。