Interface tracking and numerical simulation of micro-bubble controlled growth in micro restrained space

通过对微机电系统微流体器件中气泡生长实验结果的分析,考虑加热元表面液体微层的作用,将微气泡生长分为晶核形成、球形气泡、受侧壁挤压的气泡、沿微通道生长的气泡4个阶段,建立了矩形微通道内微气泡控制生长物理模型;采用Level Set Method模拟了矩形微通道内微气泡控制生长过程,获得了微气泡生长特性。数值模拟结果表明:微气泡初期生长速率较快,后期由于凝结率增大使生长速率减缓;液体温度、微通道宽度、微加热元宽度、加热电压等均对气泡生长始点和生长速率有显著影响。Based on the experimental results of micro-bubble controlled growth in MEMS(micro-electro-mechanical system)devices,the bubble growth process could be divided into four stages,namely,nucleating,spherical bubble,bubble restrained by lateral wall,bubble elongating along the channel.A physical model of micro-bubble growth in the rectangular microchannel was established by considering the micro layer of liquid in the heater.Numerical simulation of micro-bubble growth in the micro restrained space was performed by the Level Set Method and the characteristics of micro-bubble growth were obtained and analyzed.The simulated data showed that micro-bubble grew rapidly in the early stage but grew slowly in the late stage due to the increasing condensation rate on the interface.The results also indicated that the initial temperature of liquid,width of the microchannel,width of the microheater,and the heating voltage had remarkable effects on the bubble inception and bubble growth rate.国家自然科学基金项目(50406019);; 中国博士后科学基金项目(2004035669);; 江苏省博士后科学研究资助计划项目(苏人通2004[计]300号)~

Micro-bubble controlled growth in rectangular microchannel of micro-electro-mechanical systems

采用微机电系统(MEMS)硅加工工艺,设计、加工出了6种不同规格的实验用微气泡控制生长MEMS器件;构建了MEMS器件中微气泡控制生长实验系统并完成了实验,讨论了热负荷、微加热元宽度、微通道截面参数、工质流速及物性参数等对微气泡生长的影响。结果表明:同等实验条件下,加热电压幅值越高,微气泡生长速率越快;加热脉冲宽度仅对微气泡形成后的进一步生长有影响;加热条件相同的前提下,微加热元宽度越大,气泡成核所需的时间越短、微气泡生长速率越快;微通道宽度一定且高宽比大于1的条件下,高宽比越小,后期微气泡生长速率越慢;微流体的流速越高,微气泡生长始点越晚、生长速率也越低。相同实验条件下,R113、FC-72、去离子水三者中,R113中微气泡生长始点最靠前、生长速率最快,去离子水中微气泡生长最靠后、生长速率最慢。With the silicon microfabrication process,six micro-electro-mechanical systems(MEMS) devices for exploring micro-bubble growth were designed and fabricated.Experimental investigations of micro-bubble growth in micro restrained space were performed.The results showed that the micro-bubble growth rate was influenced by heat power,dimensions of microheater,microchannel section,microfluidic velocity,and materials of the fluid.A higher heating voltage resulted in faster bubble growth.The width of heating pulse took effect during the latter period of bubble growth.Under the same heating voltage and pulse width,a larger width of the microheater led to faster bubble growth.When the aspect ratio of the microchannel section was over 1.0,a smaller aspect ratio brought on slower bubble growth during the latter period.The larger the microfluidic velocity,the later the bubble growth start point,and the slower the bubble growth.Under the same test condition,the bubble growth rate of R113 was the largest among the three working fluids,followed by FC-72 and deionized water,due to the effect of thermophysical parameters of the fluids.国家自然科学基金项目(50406019);; 中国博士后科学基金项目(2004035669);; 江苏省博士后科学研究资助计划项目(苏人通2004[计]300号)~

女子短大生を対象としたウエイトコントロール教室の試み

We carried out weight control class from October 1993 to March 1994, to give a method of reasonable weight control and think it among women college students. The results are as follows; 1) At first 37 students attended, but 25 students were measured for the fundamental items. Only 2 students were continued to record weight, steps and foods for about six months. 2) The mean value of height, weight, Body Mass Index (BMI) were 158.8±4.0cm, 56.5±5.1kg, 23. 4±1.6 respectively. Forarm cirumference (left), upperarm circumference (left and right), upperarm circumference, fixed (right), the supersonic waves method (umbilical region) and back extension of the physical education students were significantly higher than the nutrition students. 3) Blood examination and routine urinalysis were within normal limit. 4) Among 25 students, 10 students had experience in diet. Indefinite complaints were 17 items in 27. The order of the dissatisfaction of figure of the students were the legs, the whole body, the weight, the waist, the hips, the breast. 5) The averge for 5 points in egogram was 11.0, Nuturing Parent (NP) was 13.4 the highest, Adult (A) and Critical Parent (CP) were 9.5 and 9.9 respectively. 6) The participation term at the weight control class, were 24 weeks (Case 1) and 18 weeks (Case 2). Weight of 1.2kg incresed in Case 1, and in Case 2 the weight did not change with some fluctuations during the term

弹道靶上的跨音速实验

本文介绍用弹道靶作跨音速试验的新方法,在二级轻气炮上采用了二个特殊的新技术:充气放炮能发射模型达到亚音速,低充填条件能发射模型达到跨、超音速。由于初始加速度较小,发射的模型外形完整,姿态稳定;加上没有支撑干扰和小洞壁效应的优点,使弹道靶设备在跨音速实验方面有特殊的优越性,用上述技术得到了圆球跨音速流场的清晰照片,其中击波脱体距离、分离点位置、颈部宽度、尾迹形状与超音速、高超音速流动比较有明显变化。文中M≈1.010和M≈0.99的二张全流场照片是十分有意义的。最后提出一个想法,用靶场加压、降温的方法可以提高雷诺数直到10~7以上

Plant functional type diversity in the Otindag Sandland

植物随所处环境条件的变化而产生一系列的形态、生理以及其它特性上的相应变化，形成相应的适应对策，表现出一定的功能策略。把在生态系统中扮演着相似角色并且对环境条件表现出相似的响应的一组具有相似特征（形态和生理特征）的植物称为植物功能型（Plant Functional types），这一概念把植物从个体水平和整个生态系统水平上把生理和生活史过程以及策略合理的联系在一起。有了植物功能型的帮助，我们能够将个体种和个体种群的纷繁 复杂过程总结简化为相对简洁的演化模式。近来的研究已经提出在生态系统过程中功能型多样性比物种多样性更重要。 本文以浑善达克沙地植被为研究对象，按照生命期（一年生与多年生），光合途径（C3光合途径与 C4光合途径），繁殖方式（克隆繁殖和非克隆繁殖）以及生长型（禾草与非禾草）来划分浑善达克沙地的植物功能型，调查监测浑善达克沙地植物功能型的分布及其生态特征对沙地环境的响应。 通过对浑善达克沙地五种不同生境的土壤因子和植物功能型分布及其群落特征的分析研究，结果表明在流动沙丘上一年生C4非克隆繁殖的植物功能型首先侵入，半固定沙丘开始有多年生C3植物功能型定居并逐渐成为优势种，当成为固定沙丘时，本研究中所有浑善达克沙地植物功能型都出现了，其植物功能型多样性最高。滩地中的土壤的有机质和养分含量最高，多年生C3植物占据绝对优势。靠近淖尔边缘，盐分含量和水分增加，多年生C3非禾草成为优势种。在浑善达克沙地，一年生C4非克隆非禾草在沙丘生境中全都存在。流动沙丘、半固定沙丘和固定沙丘之间的土壤条件没有显著差异，但植被特征存在差异。因此，只要排除人为影响和牲畜干扰，辅助以一定的人工措施（如飞播），浑善达克沙地退化草地将向着良性的恢复方向发展。 通过对浑善达克沙地退化草地围封后的植物功能型特征变化研究，在四年的植被恢复过程中，功能型多样性最高的群落可能不是最稳定和恢复时间较长的群落，在我们的研究中，功能型多样性在恢复的第一年和第四年较高，而在恢复的第二年和第三年功能型多样性显著低于第一年和第四年。但第二年和第三年的地上生物量却高于第一年和第四年，从生态系统功能的角度考虑，说明恢复过程中群落的稳定性是短暂过渡的类型，群落恢复过程将呈周期性的波动。在四年的恢复时间里，多年生C3光合途径克隆繁殖禾草无论从植株密度、盖度、物种数以及地上生物量都在群落中占有绝对优势，在退化沙地草地自然恢复早期起到关键作用。 基于连续四年在浑善达克沙地围封区内滩地植被记录，分析了（1）滩地植物群落的植物功能型特征，包括密度、物种数、盖度、地上生物量以及相对重要值；（2）各植物功能型特征对植物功能型多样性（Shannon-Wiener index）的贡献以及(3) 群落初级生产力与物种多样性和植物功能型多样性的关系。结果表明，植物功能型特征显著受生命期、光合途径、繁殖方式以及生长型影响。植物功能型多样性与群落物种数显著相关。逐步回归分析结果显示多年生C3 克隆禾草随着退化草地的恢复进程对植物功能型多样性的影响越来越重要。植物功能型多样性与群落初级生产力之间的关系随着恢复进程而呈现不同的线性关系。 为了调查浑善达克沙地主要植物功能型优势物种对沙地环境的适应，研究了多年生根茎克隆繁殖禾草赖草和多年生非克隆繁殖非禾草褐沙蒿对沙埋和风蚀的响应。结果表明，不同的植物功能型对于沙地风沙蚀积表现出不同的适应对策。在一定程度的沙埋和风蚀胁迫下，赖草通过分株间克隆整合来抵御风沙蚀积，通过对根茎生物量的投资，来逃离胁迫环境。而褐沙蒿通过加大对根生物量的投资来抵御风蚀，通过加大对地上部分的生物量投资来抵御沙埋