Grazing by a resident macrozooplankton community and non-resident Daphnia carinata King: A preliminary in situ incubation study

A 24 h incubation study was conducted in situ in Manly Dam reservoir, Sydney, Australia. The study aimed to evaluate the relative effectiveness of grazing on phytoplankton by a resident macrozooplankton community, dominated by the cladoceran Ceriodaphnia and some copepods, in comparison with grazing by added, non-resident Daphnia carinata in the absence of the resident macrozooplankton community. Although there was some variability in the measured grazing rates among incubation bottles (volume: 1.28 L), D. carinata with a mean body size of 30.8 μg dry weight were more efficient grazers than the reservoir macrozooplankton community with a mean body size of 2.5 μg dry weight. The weight-specific clearance rate of D. carinata was 2–65 times higher than that of the resident reservoir community for five taxa of reservoir phytoplankton examined. In comparing the evidence from the literature on the limited ability of D. carinata to graze on cyanobacteria, a management strategy using D. carinata for the reduction of phytoplankton biomass may need to be considered separately from one designed to specifically control undesirable taxa, such as the cyanobacteria Microcystis and Anabaena .     

用流泵测定土的渗透系数

近年来美国的一些实验室，开始将流泵（ｆｌｏｗｐｕｍｐ）用于渗透仪，以代替传统的渗流试验装置。与达西渗透仪相比，用流泵测定土的渗透系数，不仅操作简便易行，试验时间大为节省，而且试验结果稳定可靠，精度高，试验的可重复性强。     

高碾压混凝土重力坝防渗结构型式研究

针对碾压混凝土及碾压混凝土坝的渗流特性，结合碾压混凝土坝防渗设计的主要原则，评述了国内外碾压混凝土筑坝过程中所采用的主要防渗结构形式，并总结出能满足渗控要求，又能充分发挥碾压混凝土施工特长的高碾压混凝土重力坝的防渗结构的形式和优选渗控设计方案。     

Macroeconomic policies and performance in Latin America

This paper provides new evidence on macroeconomic policies and results in Latin America and the Caribbean. Results are: (i) credibility allows adoption of counter-cyclical macroeconomic policies; (ii) accuracy in meeting inflation targets depends on central bank independence and country risk; (iii) intermediate exchange rate (ER) regimes have become less persistent; (iv) ER regimes matter for inflation and growth; (v) real ER trends are not explained by productivity growth and supply reforms do not resolve real ER misalignments; (vi) financial integration has increased significantly; (vii) foreign shocks are a major growth determinant; and (viii) composition of foreign capital inflows matters for growth.     

MIRR: A better measure

Over the past 60 years Net Present Value (NPV) and the Internal Rate of Return (IRR) have emerged from obscurity to become the overwhelming choices for the quantitative measurement of investment attractiveness in modern corporations. Despite their current popularity, neither NPV nor IRR was designed to deal effectively with the vast majority of investment problems, meaning those where periodic free cash flows are generated between the time of asset purchase and the time of sale. NPV assumes that periodic cash flows can and will be reinvested at the NPV discount rate, either at the cost of capital or another risk adjusted discount rate; IRR assumes reinvestment at the IRR. Neither assumption is usually realistic. In addition, when evaluating projects in terms of their financial attractiveness, the two measures may rank projects differently. This becomes important when capital budgets are limited. Finally, a project may have several IRRs if cash flows go from negative to positive more than once. The Modified Internal Rate of Return (MIRR), discovered in the 18th century, does account for these cash flows. This article explains the problems with NPV and IRR, describes how MIRR works, and demonstrates how MIRR deals with weaknesses in NPV and IRR.     

社上水库砌石坝(副坝)渗漏量变化特性分析

从水库运行情况及砌石坝地质，防渗结构，砌体质量着手，分析漏疸化变化也库水位，温度渗漏水质的相互关系。     

牛屯河堤防工程防渗墙及减压沟渗控效果分析

针对牛屯河堤防工程中所采用的不同渗控措施 ,利用各堤段监测断面的测孔水位资料对堤基渗流情况进行了分析 ,对塑性混凝土薄型防渗墙、深层搅拌桩防渗墙及减压沟的渗控效果作出了评价。     

岩体裂隙水流的运动规律

对岩体裂隙水流运动规律进行了探讨。分别导出了Forchheimer渗流方程中系数a，b的表达式，它既适用于充填裂隙水流，又适用于非充填裂隙水流。大量试验表明，该式还适用于描述线性和非线性渗透运动。     

PE复合土工膜在红江水库除险加固中的应用

红江水库为沥青斜墙土坝 ,最大坝高 45.0m ,由于坝端混凝土齿墙未达相对不透水层 ,而后浇的混凝土铺盖过短 ,因此渗透比降大 ,工程自建成蓄水后 ,先后发生过多次渗透破坏事故 ,被定为三类危险水库 ,控制水位运行。本工程除险加固采用复合土工膜全坝及坝端外延铺设 ,延长渗径 ,减少渗透比降 ,达到除险加固目的。从 1 996年 9月竣工验收蓄水 3年多高水位运行观测看 ,大坝无异常现象 ,渗流量及斜墙下干砌石垫层入渗水位明显减少 ,达到了预期防渗加固的效果。     

风化料在坝体防渗中的应用

风化料做坝体防渗的防渗性能、预防拱效应作用,以及其用作防渗体的良好力学性质,阐述了风化料的应用前景。