Dynamics of photosynthetic pigments in an Andean lake in Colombia

Guatavita Lake is a small, sheltered tropical high mountain lake located in the Colombian Andes, with a closed watershed and a maximum depth of 25 m. It is the freshwater source for human consumption in nearby small towns, as well as being a site of cultural value for the country, as it was a sacred place to indigenous peoples until about five centuries ago. As the structure and function of this aquatic ecosystem is poorly understood, this study provides initial knowledge on its phytoplankton biomass dynamics, which should be useful in designing efficient management plans with environmental baseline information for similar lakes elsewhere. Physical and chemical data, and photosynthetic pigment concentrations, were measured for the period November 1999–November 2000 at the central vertical axis of Guatavita Lake. The vertical profile of the chlorophyll‐a concentration was closely related to the dissolved inorganic nitrogen concentrations and the thermal stratification characteristics. The maximum chlorophyll‐a concentration in the metalimnion was recorded for the thermal stratification period (November 1999–June 2000). Deepening of the maximum chlorophyll‐a concentration began in February, continuing to June, when it reached its lowest value at the 15 m depth. The phytoplankton biomass values showed an increment within the entire water column at the beginning of the mixing period (July). The relation between the metalimnetic peak of chlorophyll‐a and the dissolved inorganic nitrogen concentration suggests the growth of the phytoplankton community is limited mainly by the availability of nitrogen.     

热带城市垃圾典型组分的热解特性研究

对热带城市垃圾的几种典型组分进行了热解实验，得到了它们的失重曲线，通过对失重曲线进行分析，得到了这几种典型组分的热解规律，并通过建立热解动力学模型，求出了其中两种组分的活化能E和频率因子A。     

我国热带地区燃料油植物资源的开发和利用

论述了我国热带地区燃料油植物资源的开发意义及燃料油植物的特点;介绍了热带地区种子或种仁含油率大于50 % 的15种燃料油植物的分布及生物学特性;提出了热带燃料油植物研究与开发利用需解决的问题和热带燃料油植物应用前景.     

基于气象大数据的台风强度预测统计模型研究

台风是一种破坏力极强的灾害性天气系统,做好台风路径和强度预报是防灾减灾的关键。除了气候性因子、台风持续性因子以及环境背景场因子,文章还考虑了在近海时,受陆地影响下,台风强度演变的情况,引入了新变量,即海陆比。将2000—2014年西北太平洋的所有台风样本分成海盆样本和近海样本,研究它们在12、24、36和48小时间隔的强度演变规律。本研究利用1°×1°美国国家环境预报中心/美国国家大气研究中心提供的 FNL全球再分析资料(Final Operational Global Analysis)数据,采用逐步回归和主成分分析法的多元统计回归模型预测台风强度,并比较了两种模型在台风强度预测上的表现。综合深海盆和近海台风强度的预测结果可以看出,文章提供的近海台风强度预报方法,比国内外的其他研究更具有防台减灾的实际应用价值。     

热带海岛地区多种围护结构隔热构造做法应用性能研究

以海南省一典型居住建筑为对象,分析多种围护结构做法的热工性能及构造做法对建筑能耗的影响。结果表明,热带海岛地区较常使用的通风屋面由于气流堵塞已不能满足隔热节能要求,应在空气间层上方铺设泡沫玻璃或泡沫混凝土隔热层。蒸压加气混凝土隔热性能显著,建筑内表面最高温度可保持在35．59℃的较低水平．隔热反射涂料可有效降低建筑空调能耗。     

Monitoring wind effects of a landfall typhoon on a 600 m high skyscraper

This article presents the observations of the atmospheric boundary layer (ABL) and wind effects on a 600 m high skyscraper during a landfall typhoon. Wind structure and characteristics throughout the entire ABL are presented and discussed based on records from a Doppler radar wind profiler and near-ground measurements at several meteorological stations. Wind speed profiles with the feature of low-level jets and radial-distance and exposure dependences of gradient height are stressed. Afterwards, wind-induced pressures on building surfaces of the skyscraper are investigated with highlights on non-Gaussian probability distributions of negative pressures and vortex shedding occurred alternately at two sides of the building. The structural responses measured by both accelerometers and strain gauges are analyzed subsequently. Modal parameters of the skyscraper and their dependence on response amplitude are presented and discussed. This study aims to provide useful information for the wind-resistant design of skyscrapers in tropic cyclone-prone regions.     

基于地域的景观温室热带雨林展示区 景观设计

通过对原生热带雨林景观特征的研究以及中国3个 以植物原生境为展示特色的植物园景观温室热带雨林展示区的 调查研究,发现景观温室设计上对雨林原生状态景观的表现存 在雨林类型呈现不完全、地域性不足、整体性不明显等问题。 在世界热带雨林各分布区地域特征分析的基础上,提出景观温 室热带雨林展示区以非洲雨林群系、美洲雨林群系以及印度- 马来雨林群系作为主题。从不同地域主题出发,从地形、土 壤、水体、文化、植物等景观要素的设置上进行景观设计,旨 在展现不同雨林群系的地域特色,为景观温室热带雨林展示区 景观设计提供参考。     

一段炉转化管热带现象原因分析及处理

针对转化管出现的热带(超温)现象,结合一段炉的运行数据,从转化管改薄壁管、催化剂活性降低、催化剂结炭等方面进行分析与探讨,并采取一系列的操作优化及烧炭处理,避免了装置的停车,保证了系统的长周期稳定运行。     

Effect of silica fume on cement hydration and temperature rise of concrete in tropical environment

Investigated herein is the effect of temperature on heat development in cement pastes and concretes with and without silica fume cured at relatively high temperatures often encountered in tropical environment. With an initial temperature of 30°C, adiabatic temperature rise of the concrete with 8% silica fume as cement replacement was similar to that of the control Portland cement concrete up to about 18 h. After 24 h, however, the temperature of the silica fume concrete was lower than that of the control concrete. Since the concrete with 8% silica fume had a higher 28-day compressive strength (72.5 MPa) than the control concrete without silica fume (59.2 MPa), the concrete with silica fume is likely to have a lower temperature rise as compared with the control concrete of equivalent 28-day strength by reducing cementitious materials content with the same water content. The extent of heat evolution in the silica fume pastes was generally greater at lower temperatures of 20–50°C, but less at 65°C than in the control paste. At the relatively high curing temperatures, the degree of cement hydration in the paste with silica fume was lower than that in the control cement paste at early ages. However, the pozzolanic reaction started even before 24 h after water was added.     

Ecological consequences of hydropower development in Central America: impacts of small dams and water diversion on neotropical stream fish assemblages

Small dams for hydropower have caused widespread alteration of Central American rivers, yet much of recent development has gone undocumented by scientists and conservationists. We examined the ecological effects of a small hydropower plant (Doña Julia Hydroelectric Center) on two low‐order streams (the Puerto Viejo River and Quebradon stream) draining a mountainous area of Costa Rica. Operation of the Doña Julia plant has dewatered these streams, reducing discharge to ～10% of average annual flow. This study compared fish assemblage composition and aquatic habitat upstream and downstream of diversion dams on two streams and along a ～4 km dewatered reach of the Puerto Viejo River in an attempt to evaluate current instream flow recommendations for regulated Costa Rican streams. Our results indicated that fish assemblages directly upstream and downstream of the dam on the third order Puerto Viejo River were dissimilar, suggesting that the small dam (< 15 m high) hindered movement of fishes. Along the ～4 km dewatered reach of the Puerto Viejo River, species count increased with downstream distance from the dam. However, estimated species richness and overall fish abundance were not significantly correlated with downstream distance from the dam. Our results suggested that effects of stream dewatering may be most pronounced for a subset of species with more complex reproductive requirements, classified as equilibrium‐type species based on their life‐history. In the absence of changes to current operations, we expect that fish assemblages in the Puerto Viejo River will be increasingly dominated by opportunistic‐type, colonizing fish species. Operations of many other small hydropower plants in Costa Rica and other parts of Central America mirror those of Doña Julia; the methods and results of this study may be applicable to some of those projects. Copyright © 2006 John Wiley & Sons, Ltd.