EXPERIMENTAL INVESTIGATIONS ON LONGITUDINAL DISPERSION CHARACTERISTICS OF TIDAL RIVERS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＵｎｄｅｒｔｈｅｉｎｆｌｕｅｎｃｅｏｆｎａｔｕｒａｌｔｉｄｅｓ,ｔｈｅｉｎｔｅｒａｃ ｔｉｏｎｓｂｅｔｗｅｅｎｆｌｏｗｆｅａｔｕｒｅｓａｎｄｐｏｌｌｕｔａｎｔｌｏｎｇｉｔｕｄｉｎａｌｄｉｆｆｕｓｉｏｎｉｎｔｉｄａｌｒｉｖｅｒｓａｒｅｉｍｐｏｒｔａｎｔｆｏｒｗａｔｅｒｅｎｖｉ ｒｏｎｍｅｎｔｒｅｃｔｉｆｉｃａｔｉｏｎｉｎｅｓｔｕａｒｉｎｅｒｅｇｉｏｎｓ.Ｔｈｅｄｉｆｆｕ ｓｉｏｎａｎｄｔｒａｎｓｐｏｒｔｏｆｐｏｌｌｕｔａｎｔｉｎｎａｔｕｒａｌｒｉｖｅｒｓｆａｌｌｉｎ ｔｏｍ…     

横泉水库旧坝体及黄土台地强夯处理实践

山西省横泉水库在原有遗留工程基础上进行重新建设，以往的4次施工，填兢了长400m、高17m左右的左岸坝体，填土约120万m^3，但坝体填筑质量极差，干客重和渗透系数根本无法满足设计要求。此次重新建设，决定对这部分干客重不迭设计要求且具有湿陷性的左岸旧坝体以及左岸黄土台地进行强夯处理，对坝体进行强夯处理在省内还是首次进行，在国内也比较少见，通过处理，坝体质量达到了设计要求，并且节约了投资，效果明显。     

Crystallization and thermoelectric behavior of conductive-filler-filled poly(ε-caprolactone)/poly(vinyl butyral)/montmorillonite nanocomposites

Crystallization and thermoelectric properties of poly(ε-caprolactone) (PCL)/poly(vinyl butyral) (PVB)/montmorillonite (MMT) nanocomposites containing carbon black (CB) have been studied as a functions of a small amount of amorphous PVB content and a wide range of molecular weight of PVB. X-ray diffraction data of PCL/PVB/MMT nanocomposites indicates most of the swellable silicate layers are exfoliated and randomly dispersed into PCL/PVB system. The band spacings of PCL spherulites in PCL/PVB/MMT nanocomposites decrease with increasing PVB content, and this indicates that increasing the PVB content greatly shortens the period of lamellar twisting. The presence of 1 wt% MMT and higher molecular weight of PVB also shorten the period of PCL lamellar twisting. Nucleation and crystallization parameters, such as growth rate G and Avrami exponent n, can be determined by using POM and DSC isothermally crystallized at 41 °C. For samples with the same CB content, the intensity of positive temperature coefficient (PTC) (I_PTC, defined as the ratio of peak resistivity to resistivity at room temperature) of the nanocomposites was increased as the content and the molecular weight of PVB increases. The change of the PTC property related to the morphological difference (i.e. period of lamellar twisting) in the nanocomposites can be discussed.     

螺旋翅片管的换热计算

本文引入区域平均表面传热系数的概念。在实验研究的基础上进行了肋基和肋端温度分布预测及肋片换热数值计算。     

部分种子成分的特征X射线在等效生物材料中衰减的测定

用Ｓｉ（Ｌｉ）探测器实现了Ｎａ、Ｍｇ、Ｓ、Ｃｌ的特征Ｘ射线在有机膜中的相对衰减以及与Ｏ、Ｋ元素的特征Ｘ射线能量相当的Ｘ射线或轫致辐射在有机膜中的相对衰减，分别得出了它们减的数学描述，并把实验得到不同能量的Ｘ射线在有机膜中的质量吸收系数与Ｂｅｒｋｅｌｅｙ的ＯＣＧ软件计算出的结果相比，相关都小于３０％。     

烃类在三甘醇和四甘醇中无限稀释活度系数的测定与关联

用气相色谱法分别测定了苯、甲苯、乙苯、正庚烷、正辛烷、正壬烷和正癸烷在三甘醇和四甘醇中的无限稀释活度系数 ,测定温度范围为 5 0～ 13 0℃。用修正的UNIFAC模型 (Dortmund)对上述不同温度下的无限稀释活度系数实验数据进行关联 ,得到了三甘醇和四甘醇与其它基团的相互作用参数 ,并将计算结果与实测值进行了比较。     

Ce,Eu双掺BSO晶体光折变效应研究

在ＢＳＯ晶体中同时掺入Ｃｅ和Ｅｕ离子，生长了Ｃｅ：Ｅｕ：ＢＳＯ晶体，对晶体的二波耦合和四波混频性能了测试。结果表明，Ｃｅ和Ｅｕ离子对晶体的光折变效应起到了增强的作用。     

Prediction of evaporation heat transfer coefficient and pressure drop of refrigerant mixtures

A study on the prediction of heat transfer coefficient (HTC) and pressure drop of refrigerant mixtures is reported. HTCs and pressure drops of prospective mixtures to replace R12 and R22 are predicted on the same cooling capacity basis. Results indicate that nucleate boiling is suppressed at qualities greater than 20.0% for all mixtures and evaporation becomes the main heat transfer mechanism. For the same capacity, some mixtures containing R32 and R152a show 8.0–10.0% increase in HTCs. Some mixtures with large volatility difference exhibit as much as 55.0% reduction compared with R12 and R22, caused by mass transfer resistance and property degradation due to mixing (32.0%) and reduced mass flow rates (23.0%). Other mixtures with moderate volatility difference exhibit 20.0–30.0% degradation due mainly to reduced mass flow rates. The overall impact of heat transfer degradation, however, is insignificant if major heat transfer resistance exists in the heat transfer fluid side (air system). If the resistance in the heat transfer fluid side is of the same order of magnitude as that on the refrigerant side (water system), considerable reduction in overall HTC of up to 20% is expected. A study of the effect of uncertainties in transport properties on heat transfer shows that transport properties of liquid affect heat transfer more than other properties. Uncertainty of 10.0% in transport properties causes a change of less than 6% in heat transfer prediction.     

Performance of absorption refrigeration cycle at maximum cooling rate

The influence of irreversibility of finite-rate heat transfer on the performance of an absorption refrigerator is investigated using an endoreversible cycle model with continuous flow. The cooling rate is adopted as an objective function for refrigerator optimization. The maximum cooling rate and the corresponding coefficient of performance are derived. The optimal performance with respect to heat transfer areas of the refrigerator is analysed. In addition, certain significant conclusions are reached.