室内自然置换通风受热墙体特性研究与实验模拟探讨

分析了含有热源的室内自然置换通风过程中热力分层的流动机理,探索了自然置换通风室内气流分层的理论模型。实验研究含有单面受热垂直墙体(如太阳照射受热墙体)的室内无因次有效通风面积与热力分层界面无因次高度的函数关系,并确定出自然置换通风的室内环境空气层的厚度仅为无因次有效通风面积的函数,实验发现无因次稳定分层分布大约成线性分布。     

A preliminary hydrosedimentary view of a highly turbid,tropical, manmade lake: Cointzio Reservoir (Michoacán,Mexico)

This study represents the first limnological assessment of Cointzio Reservoir (Michoacán, Mexico). A full three‐dimensional scan of temperature, conductivity and turbidity was done for the reservoir during two field surveys at the end of the 2005 rainy season (December 2005), and before the beginning of the next season (May 2006). These parameters also were measured continuously during the 2006 rainy season. Analysis of data within the context of local climate trends at a multidecadal scale indicates the reservoir can amplify seasonal features because of its morphometric properties. Between June to December, the reservoir behaved as a fluvial system, exhibiting a rapid, efficient mixing of the water column. Between January to May, the reservoir developed substantial stratification, and exhibited typical lacustrine characteristics. These alternate phases of fluvial and lacustrine regimes, associated with a high water turbidity throughout the year (Secchi depth of ≈0.2 m) contributes to stress on this aquatic ecosystem.     

The joint effects of riverine,thermal, and wind forcing on a temperate fjord lake: Quesnel Lake,Canada

Field data obtained in 2003–2004 are used to describe the influence of atmospheric and riverine forcing on the thermal history of fjord-type lakes using Quesnel Lake, British Columbia, Canada as an example. Typical of fjord-type lakes, Quesnel Lake is narrow, long (> 100 km total thalweg), multi-armed (three arms of comparable size), deep (maximum depth > 500 m), and has multiple basins separated by sills. The lake's annual thermal history responds to the joint forcing of surface heat exchange, river inputs, and wind stress. The lake's annual heat budget is dominated by surface radiative fluxes, and riverine input of heat is insignificant in this medium residence time lake (10 years). Despite being insignificant to the annual heat budget, the three major rivers that feed the three arms of the lake contribute to the overall lake circulation pattern. Since these rivers have differing salinities, it is possible to identify, using temperature/salinity correlation diagrams, patterns of riverine circulation interflowing in the lake. Data from a 1-year thermistor-chain record suggests exchange between surface and intermediate waters occurs twice annually, but deep-waters below 150–250 m are mainly renewed during autumn, by strong and episodic atmospheric forcing. This is because wind-forced turbulent diffusion and gravitational convection triggered by wind forced displacement of isotherms (initiating thermobaric instability) are required for full overturn and deep-water renewal.     

Beyond Stratification: The Emerging Class Structure in Rural Russia

Using survey data from Russian villages, this article examines the development of a rural class structure in postcommunist Russia. It is argued that as a result of market reforms, social and economic relations have evolved beyond stratification, and that, rather, a rural class structure is emerging. Five measures of an emerging class structure are posited: income stratification, land holdings, capital stock, class consciousness, and shared attitudes and values. Focusing on upper and lower income strata, significant differences are documented for each measure. The economic and political implications of the findings are discussed.     

Seasonal patterns of thermal stratification and primary production in the northern parts of Lake Tanganyika

Thermal stratification in meromictic Lake Tanganyika weakens during the cool, dry and windy season, allowing intrusions of deeper nutrient-rich waters into the upper mixed layer enhancing primary productivity. The current study examined the seasonal influence of thermal structure on the patterns of primary production in Lake Tanganyika. Two sites (Kigoma Bay and Mahale) were sampled on a monthly basis for 1?year. Water temperature and chlorophyll a fluorescence profiles (0–100?m) were measured using a multisonde. Water samples were taken every 20?m (0–100?m) to measure soluble reactive phosphorus (SRP), chlorophyll a and primary production. Pulse Amplitude Modulated Fluorometry was used for the measurements of primary production. The results show that the dry season coincided with higher wind speeds, elevated SRP and some peaks of chlorophyll a and primary production at both sites. During the wet season, high levels of chlorophyll a and primary production coincided with an increase in the euphotic depth, a deep chlorophyll maximum (DCM) and a contribution from metalimnetic areal production at both sites. Our results suggest that the vertical distribution of primary production in Lake Tanganyika is affected by the lake thermal structure, nutrient availability and the extent of the euphotic zone. In Lake Tanganyika, estimates of areal primary production were significantly affected by DCM and required estimation throughout the entire upper mixed layer and the metalimnion which extended to ~89?m.     

Minimizing environmental impact whilst securing drinking water quantity and quality demands from a reservoir

Complying with the demands of drinking water supply whilst minimizing environmental impact poses a great challenge in water management. This study investigates the potential of withdrawal management of drinking water reservoirs to alleviate the disruption of the river continuum by a reservoir dam with respect to temperature and discharge. The aim is the identification of an optimal withdrawal strategy to provide a near‐natural discharge temperature and flow for the downstream river without jeopardizing drinking water production. First, we identify the applicability of new withdrawal regimes for raw water security and downstream river demands. Second, we search for an ideal withdrawal regime in scenario simulations using a numerical reservoir model (“General Lake Model”). The scenarios on a drinking water reservoir in Germany demonstrate that we are able to derive an optimized reservoir management. The numerical model is provided for operators as a simple and efficient tool for optimizing the withdrawal strategy within reservoir management.     

乐昌峡水利枢纽拦河坝放水底孔施工技术的应用

放水底孔是乐昌峡拦河坝施工中的关键部位,上下游牛腿距离地面悬空高度11 m以上,选用贝雷架作为施工的承重平台及操作平台。进水口段为弧形,对外观要求较高,为获得良好的施工效果,采用异形定制钢模板保证放水底孔的外观,并进行合理的砼浇筑分层施工,优化施工组织,保证砼的浇筑质量。     

我国居民收入基尼系数的估计及城乡阶层效应——基于城镇、农村收入20分组数据的研究

基于2013年调整的城镇、农村居民20分组收入数据,文章再估计了我国2005-2012年的城镇、农村及城乡混合的基尼系数,结果表明,我国总体基尼系数由2005年的0.4563下降到2012年的0.4293,城镇基尼系数有下降趋势,农村基尼系数较稳定;比较研究发现,以往基于未调整的农村分组数据的基尼系数估计会由于缺少大量高收入群体信息而高估了农村基尼系数,从而高估了总体基尼系数。而且,基于Yitzhaki（1994）的城乡分解框架,我们发现,城乡内部差距比城乡间差距对总体差距的贡献更大;城镇收入分布的阶层效应比农村的更强,即城镇群体更加趋向于形成一个阶层,而且我国的城乡阶层效应越来越明显。     

Sediment Resuspension and Currents in Lake Manitoba

The physical resuspension of bottom sediment during periods of high winds is thought to be important for nutrient recycling in large shallow lakes. In order to study resuspension, prototype instrumentation designed to collect gram quantities of suspended sediment at 38.1-cm intervals in the water column was deployed in 4.2 m of water in the shallow southern basin of Lake Manitoba for 1-month periods in 1978 and 1981. At about 2.7 m depth a sharp discontinuity was observed in the vertical distribution of total mass of suspended sediment collected. The mean current speed varied linearly with depth above the discontinuity but was more uniform near bottom. Although the water column was not thermally stratified, drogues frequently displayed a two-layer structure in the currents with a high skew in direction between layers. The particle size distributions were similarly discontinuous in the vertical, with large quantities of sand in the upper layer samples and a high silt load in the lower. The unusual particle size distribution, which was explained in terms of the origin of resuspended sediments and subsequent transport by lake currents, suggests a decoupling of lake turbulence between the two layers during high winds.     

The foundations of Chinese attitudes towards advocating luxury spending

Abstract

In China, some scholars have argued that luxury spending is socially beneficial to equalise wealth, under the assumption that the total endowment of resources is a fixed amount. This argument is not only consistent with Confucianism but also might point to another lesser known side of Confucianism that the luxury spending of the rich can be regarded as a wealth-transferring mechanism. Furthermore, luxury spending was encouraged for purposes of enjoyment; it did not involve the consideration of power and protection. This is in sharp contrast to the extravagance of the European nobility; their intention was to maintain a hierarchical structure.