大气中非线性波和孤立波——有热源影响的非线性重力惯性内波

本文考虑有外界热源情况下的非线性重力惯性内波,首先我们讨论了波解存在的条件及得到了解析解的表达式。然后我们利用拟能影响函数中的根与系数之间关系,导出一个无量纲的量M,利用M把周期解存在条件转化为M>2/3,当M→2/3时,就得到了区别于KdV方程的孤立波解。最后利用M我们建立了非线性波的波速公式,波速C与振幅,特征散度,M之间的关系,当波速公式向线性化波速公式退化时,我们发现当M≥l时系统呈线性效应;当2/3相似文献   

基于ISP器件的可编程变量程数字频率计的设计研究

用ispLSIl032设计了可编程变量程数字频率计逻辑电路，此电路适于工业控制领域的伺服系统和人们日常生活中对数字信号频率的测量．     

覆膜电极溶解氧测定仪零值误差和温度示值误差的探讨

对覆膜电极溶解氧测定仪检定规程的新旧版本进行了比较.指出了新规程在零值误差和温度示值误差两个指标的性能规定上存在的问题.在理论分析的基础上,给出了两个指标合理的示值范围.     

多波长激光功率计的设计

根据硅光电池的物理特性,设计出可测量连续激光的功率计。该功率计可对多个波长进行测量,且精度较高,在实验中有较强的实用性和较高利用率。     

基于数字摄像的测量观测系统设计

在大气能见度观测中,相关研究多集中于白天观测,夜间观测的研究比较少见,而对于昼夜连续观测的研究更是鲜有报道。目前,国内外尚没有完全按照能见度定义研制的大气能见度自动观测仪出现。针对这一问题,基于CCD数字摄像技术,模拟人工观测光学原理,提出了一种能够昼夜进行大气能见度连续观测的方法。该方法基于对目标物获得能见度计算公式,并针对昼夜模式下的系统参数进行修正,能够有效消除外在环境因素和相机自身系统内部因素引发的观测误差。为验证算法的有效性,针对天空遮挡、半遮挡和空旷等不同情况（不同情况,会影响观测环境的亮度,以此测试系统对杂散光的抵抗能力,以及对不同环境的适应能力）,搭建了基于该方法的3套原理样机。利用搭建的数字摄像能见度仪（DPVS）在北京地区进行了实际的大气能见度分钟级观测。观测实验表明,基于该方法构建的观测系统,不但具有较宽的观测范围,而且能够有效适应各类复杂天气情况,在雨雪霾等不同天气下,均有较好的观测效果,且无论是在能见度变化较快或者较为缓慢的情况下,DPVS系统均能够进行快速正确的响应。而透过DPVS与散射仪和透射仪这两种标准观测仪器观测结果的对比分析发现,DPVS与前两者的观测结果具有较高的相关性：0.973 1,且观测性能相当,其平均相对误差在-1.54%左右,均方根相对误差在8.82%左右。而本文算法出现的最大相对误差为-14.11%。世界气象组织MOR规定：能见度仪在满量程范围内,其最大相对误差小于20%,即认为是达到标准的能见度仪,可以投入实际观测使用。基于该算法研发的DPVS系统符合观测标准,能够投入实际使用,且DPVS系统的观测成本远比散射仪和透射仪更低,具有较好的前景和应用价值。     

Structural micromechanics of oriented polymers

To clarify whether the interfibrillar slippage occurs on plastic deformation of oriented polymers, flow creep of ultrahigh molecular weight polyethylene (UHMW PE) samples with various connectedness of microfibrils has been studied in a dead load mode at room temperature. The flow creep rate of melt-crystallized and gel-cast UHMW PE films drawn to various draw ratios, as well as of modified gel-crystallized samples (cross-linked/grafted or washed free of low molecular weight fraction) has been measured with the help of a unique laser interferometric technique (Doppler creep rate meter). The technique allows one to measure creep rates for deformation increments as small as 0.3 μ within an accuracy 1%. The interferometric technique enabled us to observe an extremely high variability of flow creep rate. It was recognized that the creep process accelerates or slows from time to time. A length of a loaded sample increased by multiple consecutive deformation jumps (or steps). The size distribution of the steps appeared to be controlled by the structure of interfibrillar regions. The influence of the latter on the variability of creep rate confirms a hypothesis that suggests a contribution of interfibrillar slippage to plastic deformation of oriented polymers. The observed phenomenon has been attributed to stick-slip motion of microfibrils and their aggregates sliding on each other under the action of applied stress. It was found that the creep rate decreases with increasing interfibrillar interaction.     

新型涡轮流量计的理论模型简

基于动量力矩定理和流体边界层理论,建立了一新型涡轮流量计的理论模型. 利用该理论模型可以分析叶轮几何参数对流量计计量性能的影响. 以一DN50 涡轮流量计为例,利用本文所建立的理论模型对该流量计的仪表系数进行了计算,并在一体积管标准装置对该流量计的仪表系数进行标定. 结果表明,计算值和实验值较为吻合,误差在±;3.5% 以内,验证了模型的有效性,从而为仪表的结构优化设计提供了理论依据.     

改进的HLLC方法及其在Baer-Nunziato模型中的应用

波速估计对HLLC方法的计算影响较大,如果取值过小,则不能抓住波系特征;如果取值过大,则会引入较大的粘性。如何确定波速已有大量的研究,但是每种方法都有一定的适用范围。本文提出一种可避免估计波速的HLLC方法,并应用于两相流Baer-Nunziato模型模拟。本文方法与三种经典的波速估计方法进行比较,针对几类典型的B-N模型初值问题,不同的波速估计方法模拟能力差异较大,而本文方法可以自动确定适当的波速,因此得到较好的模拟结果。     

微米级可降解性高吸水树脂微球的制备工艺

以淀粉与丙烯酸(AA)/丙烯酰胺(AM)为原料,采用接枝共聚的方法,在低油水比的反相悬浮体系中制备微米级可降解高吸水树脂微球,探讨了油水比、中和度、分散剂、引发剂、交联剂对树脂性能的影响.结果表明,对产物的粒径和吸水倍率影响程度由大到小依次为:丙烯酸中和度、油水比、分散剂用量、引发剂用量、交联剂用量.研究得到的最佳工艺条件为:丙烯酸中和度0.7,油水比2.5∶1,分散剂用量0.7g,引发剂用量(占单体总质量)0.3%,交联剂用量(占单体总质量)0.057%;得到产物的粒径约为1.5μm,吸水倍率为290.93g/g.     

A study on the thermal conductivity of resilient materials

The floor system of apartments must have a certain level of floor impact sound performance (light-weight impact sound is 58 dB or less, heavy-weight impact sound is 50 dB or less), and comply with the building energy code to prevent energy loss in residential buildings in Korea. In this study, expanded polystyrene (EPS), expanded polypropylene (EPP), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE) and urethane foam, which are widely used in Korea as resilient materials for floating floor system of apartments, were measured. Their thermal conductivity and apparent density were measured to analyze their thermal properties and their relation was analyzed by material. In case of resilient materials made of EPS and EPP, thermal conductivity tended to decrease as apparent density increased, whereas in case of resilient materials made of EVA and PE, as apparent density increased, thermal conductivity tended to increase as well.