INFLUENCING FACTORS FOR THE ENERGY DISSIPATION RATIO OF STEPPED SPILLWAYS

In order to search for the measure to increase the energy dissipation ratio of stepped spillways, some main influencing factors for the energy dissipation ratio of stepped spillways, such as unit discharge, dam slope, height of step and so on, were studied. The results show that the energy dissipation ratio decreases with the increase in the unit discharge and increases as the slope becomes gentle. The effects of step height on the energy dissipation ratio are closely related to unit discharge. If the unit discharge is smaller, the change of energy dissipation ratio with step height becomes greater. While, if the unit discharge is greater, the influence of step height on energy dissipation ratio is very little. According to the distributions of the turbulence kinetic energy and turbulence dissipation rate obtained by numerical simulation, the basic reason of the decrease of energy dissipation ratio with the increase in the unit discharge was discussed and some specific measures to increase the energy dissipation ratio were suggested.     

外循环反应器停留时间分布的计算

本文对外循环反应器的停留时间分布进行了分析和计算。推导了计算公式。通过电子计算机计算,得出了在不同循环比下的停留时间分布数据。提出了在某些情况下外循环反应器停留时间分布的简化计算方法。     

水力空化改性对玉米淀粉聚集态结构的影响

为了探究水力空化改性对玉米淀粉聚集态结构及物化性质的影响,本实验以玉米淀粉为研究对象,分别对其进行10、20、30、40、50 min的水力空化处理,并对处理后玉米淀粉的粒径分布、微观形貌结构、结晶结构、分子短程有序结构、膨胀力以及溶解度进行测定.结果表明:水力空化处理淀粉后,玉米淀粉颗粒的平均粒径增大,淀粉颗粒的表面...     

我国磷矿资源贫化趋势与对策探讨

介绍我国主要磷矿区资源贫化趋势,对原因进行了分析。并针对低品位磷矿及伴生资源进行综合利用,提出了一些技术与政策思路。     

羟基磷灰石陶瓷管的制备

采用两种羟基磷灰石(HA)的成浆方法,使用不同的成管芯体吸附HA料浆,并设计相应的凝固浴实现HA管的初定型以及烧结程序,扫描电镜观察表明,采用DMA c/L iC l/CT/HA系和PVA/HA系两种陶瓷配浆体系,形成的HA管形貌有显著的不同;详细探讨了HA管制作的工艺过程和样品成型的各种影响因素;样品的X射线衍射图谱分析制作工艺未使烧结后的HA陶瓷管引入异质成分。     

受热工况截面平均空泡率对漂移流模型分布参数C0的影响分析

空泡率是汽液两相流动的基本参数之一.在计算空泡率的众多模型中,Zuer-Findlay漂移流模型目前应用最为广泛.根据受热工况下局部界面参数径向分布特性实验研究结果,并通过对现有实验数据的处理,分析了受热工况下垂直上升两相流漂移流模型分布参数C0随截面平均空泡率的变化规律.证实了从过冷沸腾泡状流到饱和沸腾弹状流工况,随着空泡率的增加,分布参数C0从一个小于1的值增加到1.0～1.2.     

一种用于低电源电压的全差分运算放大器

介绍一种适于数字CMOS工艺实现的全差分运算放大器的设计。该放大器用于电源电压为3V,分辨率为10位,采样频率为40MHz的流水线结构AD的采样保持和级间增益电路中。该放大器的结构为折叠一级联结构,在0.35μmCMOS工艺中带宽为162MHz,开环增益为73dB,功耗为1.92mW。     

Effect of Recycling in the HL-1M Tokamak

Tokamak plasma discharge disruption at high density is investigated. The instability analysis on model indicates that the disruption is resulted from the energy loss arising from hydrogen recycling on the edge of the plasma. This energy loss could lead to a contraction of the current channel and the production of a disruptively unstable configuration. Using a simple model we shall investigate the implications of recycling for disruptions.The critical high-density n ≤1.6× 1020m-3 is reached in LH-1H.     

Asymmetry of Neoclassical Transport by Dipole Electric Field

Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport, For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity.     

SEBS熔融接枝MAH的接枝机理

通过原位FT-IR跟踪SEBS熔融接枝MAH的反应过程研究SEBS熔融接枝MAH接枝机理。研究结果表明,从原位FT-IR上相应官能团的吸收强度随反应时间变化规律可以看出。不同的引发剂引发SEBS熔融接枝MAH的接枝机理不一样。对引发剂A,MAH在SEBS分子链上的最易接枝位置是在-EB-段的叔碳原子,其次是仲碳原子;对引发剂B,在温度低于180℃之前,仲碳原子最易发生接枝反应,其次是叔碳原子。当温度高于180℃后,伯碳原子、仲碳原子和叔碳原子的反应速率差不多。