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1.
    
ABSTRACT: A U.S. standard gage, a weighing-type recording gage, a standard gage fitted with an Alter windshield, and a pit gage were installed to evaluate the accuracy and wind effects on rainfall catch. The study was conducted at the Stephen F. Austin Experimental Forest, about 20 km SW of Nacogdoches, Texas. A recording anemometer was also installed at a height corresponding to the standard gage orifice. Based on data from 67 storms collected over a one-year period (July 1995-August 1996), all three conventional gages consistently caught less rainfall than the reference pit gage with an average percent deficiency greater than 10 percent. However, the recording gage caught 2.7 percent less and the shielded gage caught 1 percent more than the standard gage—differences less than those reported elsewhere. The deficiencies were highly correlated with storm intensity, duration, or total rainfall. When the correction for wind effect on angle of raindrop inclination is included, the percent catch deficiency of the standard gage was reduced from 11 percent to 6 percent. The remaining errors may be attributed to wind effects (streamline vs. turbulent flow), nonrandom errors, or other unknown sources.  相似文献   

2.
谭孔庚  梁荫 《四川环境》2000,19(1):37-43
本文根据气流噪声的频率特性和发声部位,提出重点降噪与综合整治的方法,对城市气流噪声污染进行控制。  相似文献   

3.
    
This research is a three-dimensional investigation about the aerodynamic interaction between the wind flow and a single high-rise building. In order to find location(s) with high potential of velocity around the building, a wide variety of wind speeds ranging from 2 to 10 m/s is studied. On the other hand, a high-rise building with the ratio of height to width of H/W = 3 is considered. Computations are performed numerically by means of the finite volume approach. Several results are obtained in the present numerical study. For example, it is found that due to wind-structure vertical interaction, locations with enhanced velocities are developed on the building roof in which the rate of this enhancement increases with increasing the wind speed. In addition, over the building, “lines C and D” are realized as the best locations having high power potentials and low turbulence intensities. In addition, lateral wind-structure interaction revealed that for all wind speeds, location of L/W = 0.5 is the best for the small wind turbine installation.  相似文献   

4.
    
ABSTRACT: This paper presents a field investigation of collecting hydrodynamic and sediment data in Lake Okeechobee with analyses examining mechanisms affecting sediment resuspension in the lake. Lake Okeechobee is a large subtropical lake located in south central Florida. Three‐dimensional flow velocities, suspended solids concentrations (SSC), and temperatures at four locations were measured from January 18 to March 5, 2000. Analyses of these data indicate that wind is the dominant factor in driving flow velocities and therefore transporting suspended solids. Wind direction also affects the SSC, especially in the north central and west littoral areas of the lake. The surface and bottom velocity components frequently flow in opposite directions, forming a stratification of the water column and preventing suspended solids from settling out. This retention of SSC in the water column may have a strong impact on the water quality of Lake Okeechobee. This study provides valuable storm event data and mechanism analyses, which will improve our understanding of the transport of suspended solids, thermal exchanges, and flow patterns within Lake Okeechobee.  相似文献   

5.
    
Due to its simplicity and accurately measuring the flow rate, the venturi system is a special kind of pipe that is widely used in various applied fluid mixtures. One of the venturi system's important applications is ejectors devices that accurately facilitate adding air to water to sustain oxygen demand target levels in many waterworks engineering systems. This study aims to improve venturi system measurement accuracy through experimental investigation and analytical analysis for the venturi system conditional configuration parameters effect on target aeration operational efficiency. In the experiment work, different runs are implemented to characterize the performance of such aerators by describing the impact of venturi characteristics and configurations, including water flow rate, air inlets orifices diameters, inlet velocities, throat lengths, inlet angles, outlets angles, and outlet diameters on aeration efficiency. Results show that the venturi air vent diameter is an important governing parameter for determining aeration performance value. Additionally, an indicated increase in aeration performance with an increasing throat length to its diameter ratio. Meanwhile, the results revealed a varying noted effect of the venturi system characteristics and configurations on aeration performance. Moreover, the equations that relate venturi system configuration and Reynolds numbers with the aeration operational performance are developed to facilitate the target accurate aeration efficiency estimation.  相似文献   

6.
以我国滨海11个省(市)1995--2011年17年间入境旅游资料为基础,从旅游流流量、旅游流客源地空间结构和旅游流目的地空间结构方面研究入境旅游流空间结构。结果显示,滨海省(市)入境旅游流流量一直呈现持续增长态势;滨海省(市)入境旅游外国客源市场的地理集中指数处于31—34.5之间,总体趋势减小;入境游客密度指数说明滨海地区入境旅游流目的地呈现明显的非均衡态势,整体上是从中心向两翼递减的空间格局。  相似文献   

7.
When designing energy efficient buildings it is useful to study existing climate—responsive building typologies. The wind towers or wind-catchers of Yazd city in Iran are typical examples of such a typology. Although many previous studies have investigated the performance of various types of wind catcher systems, studies based on a long-term real-life measurement can be rarely found. In this study a long-term whole year monitoring campaign on an existing full scale four sided wind catcher in Yazd was carried out in 2014–2015. Three prevailing wind directions were identified and the measured on-site wind speeds were used to estimate the wind induced natural ventilation potential of the tower. A shaft/tower airflow performance index was developed. The monitoring results were compared to the ASHRAE Standard 62:2001 ventilation rate requirement. Results show that the total ventilation rate of the wind tower surpasses the ASHRAE Standard requirements. Furthermore it shows that the shafts are exposed to the prevailing wind directions perform better. For more effective natural ventilation a wind tower with adaptable openings/shafts are proposed.  相似文献   

8.
    
Forestry is the largest scale human impact affecting catchments in Finland and a prominent source of diffuse pollution in many water courses. Among the forestry activities, draining of wetlands had the most pronounced impacts on sediment, nutrient, and metal loading in the past. At present, renovation of old ditches and fertilization of peatlands constitute the major risk of forestry-induced diffuse pollution. Contemporary forestry aims at decreasing this risk with various riparian buffer strip designs. Among such designs, creation of overland flow areas by plugging the outlet ditches is increasingly used. Our objectives were to evaluate the potential of constructed overland flow areas to function as riparian buffers and estimate the quality and quantity of diffuse pollution from old versus recent forest drainages. We studied retention and release of pollutants from 20 constructed, 2- to 10-m-wide overland flow areas receiving drainage water from forested peatlands. Drainage waters were sampled above and below the plugged ditches three times per year from 1998 to 1999. Chemical oxygen demand and nutrient and metal loads and concentrations varied strongly between seasons, years, and drainage areas. Areas subjected to recent ditch renovations and fertilizations had clearly elevated seasonal loads and concentrations of total phosphorus (TP), PO4, Fe, and Al in comparison to old treatment areas. Especially TP loads were high above the national average values measured for forestry-induced diffuse pollution. In general, water quality above and below the buffer strips did not differ significantly. Our results indicate that plugged outlet ditches and associated narrow overland flow areas do not function as proper buffers in peatland areas. We suggest that wider buffers with extensive overland flow areas are needed in order to control diffuse pollution from forested and drained peatlands.  相似文献   

9.
Air Pollution Potential: Regional Study in Argentina   总被引:4,自引:0,他引:4  
/ Air pollution potential is a measure of the atmospheric conditions that are unable to transport and dilute pollutants into the air, independently of the existence of sources. This potential can be determined from two atmospheric parameters: mixing height and transport wind. In this paper a statistical analysis of the mixing height and transport wind, in order to determine the areas with high or poor atmospheric ventilation in Argentina, is presented. In order to achieve this, meteorological data registered during 1979-1982 at eight meteorological stations were used. Daily values of the maximum mixing height were calculated from observations of daily temperatures at different heights and maximum surface temperature. At the same time as the maximum mixing height, the values of the transport wind were determined from the surface windspeed and the characteristics of the ground in the surroundings of each meteorological station. The mean seasonal values for both parameters were obtained. Isopleths of the mean seasonal of the maximum mixing heights were drawn. The percentage of seasonal frequencies of poor ventilation conditions were calculated and the frequency isopleths were also drawn to determine areas with minor and major relative frequencies. It was found that the northeastern and central-eastern regions of Argentina had a high air pollution potential during the whole year. Unfavorable atmospheric ventilation conditions were also found in the central-western side of the country during the cold seasons (37.5% in autumn and 56.9% in winter). The region with the greatest atmospheric ventilation is located south of 40 degrees S, where the frequency of poor ventilation varies between 8.0% in summer and 10.8% in winter.  相似文献   

10.
    
ABSTRACT: The purpose of this paper is to present a new approach for the spatially distributed modeling of water flow during storm events. Distributed modeling of flow during storm events is an important basis for any environmental modeling, including turbidity or sediment transport. During the initial phase of a rainstorm, surface runoff is the main contributor of flow. To provide the spatial components for distributed hydrological modeling a Geographic Information System (GIS) was used to map and visualize contributing areas around a stream channel. Stream segments were defined using the hydrologic response unit (HRU) concept. Lateral flows were derived from GIS output for each segment of the stream and at each time interval of the rain storm and were routed using the kinematic routing equation. This approach is new in hydrological modeling and can be used to enhance many existing simulations. The model is also unique in the fine time scale (i.e., intervals are on the order of minutes). Model results showed good correlation with measured discharge values; however, further studies of contributing area behavior, its relationship with soil types and slope categories, and the influence of watershed size are needed to improve model performance. This model will be used in the future as the basis to model turbidity in streams.  相似文献   

11.
ABSTRACT. Over the last few years, several studies sponsored by both government and interested national engineering associations have evaluated the relative merits of pressure sewer systems. Surprisingly little data has been forthcoming, however, with regard to the effects of pressure sewers on both the economics of land development and the country's water resources. The intention of our paper is to detail the salutary effects of pressure sewers on water supply resources, the indirect effect on other resources by decreasing the contribution of sanitary sewage to their pollution, and to illustrate where, in some locations of the country, pressure sewers would benefit the economics of land development. As engineers from a large industrial firm that has built hardware that will allow the concepts stated above to become realities, we will present data to enforce our convictions. Some effects on municipal treatment plants, and emplacement costs of the system are described. Since the main thrust of our paper is to treat the effect of pressure sanitary sewers on the water resources of the country, specific peripheral data is not presented at length. The pressure sewer effects on lowering water usage in homes and the decrease in groundwater contamination by replacing septic tanks with pressure sewers in selected locations is presented. Advanced technology concepts such as energy assisted sewer systems should be considered as a favorable economic manner in which to preserve selected water resources. During the 1965 drought that affected the Northeastern section of the U.S., a federal government document reported that there was really no shortage of water, but that present water resources lacked management. Pressure sewers may be a water resources management tool and an effective one if not promulgated as a cure-all for the water pollution problems facing this nation.  相似文献   

12.
本研究项目设计了小型立式环型风洞系统和流场模拟两套实验装置。用工程流体力学实验的方法,对系统内气体压力、流量变化的调节控制方法、通风机的能量消耗,以及在检测平台系统工作段形成均匀流动流场的设计方法等工程实际问题,进行了一系列的试验研究。在试验研究的基础上确定了检测平台系统的设计方案。  相似文献   

13.
Abstract: Runoff from parking lots during summer storms injects surges of hot water into receiving water bodies. We present temperature data collected near urban storm sewer outfalls in Blacksburg, Virginia, using arrays of sensors in a stream and a stormwater pond. Surges occurred roughly a dozen times per month, ranging up to 8.1°C with average duration 2 h in the stream and up to 11.2°C with average duration 7 h in the pond. Surges were larger in the pond due to a larger contributing watershed, no dilution by upstream water, and cool background temperatures near the outfall. Surges began abruptly, warming at rates averaging 0.2°C/min for periods of 5‐20 min. Surges dissipated as they propagated into the water bodies, travelling further in the stream (>19 m) than the pond (~10 m) consistent with greater advection in the stream. Surges were largest and most frequent in the afternoon but occurred at all times of day and night. Stream surges exhibited two phases: an early high‐temperature low‐volume input from the storm sewer and a later low‐temperature high‐volume input from upstream. Surges at the pond did not exhibit two phases, consistent with inputs only from storm sewers. Surges are likely common in urban areas, and may cumulatively have consequences for aquatic organisms, biogeochemical process rates, and even human health. Such effects may be compounded by urban heat islands and climate change, so prevention or mitigation should be considered.  相似文献   

14.
将国内旅游流空间模式研究划分为旅游流圈层结构研究、旅游流时空演化规律研究和旅游流空间场效应分析三个阶段的内容,并重点探讨国内旅游流空间场效应研究的现状.通过文献分析,从基本理论、研究方法和存在的问题三个方面对旅游流空间场效应研究的相关成果进行归纳、总结,力求构建一个国内旅游流空间场效应研究的基本框架,以进一步深化对旅游流空间场效应的认识,扩宽国内旅游流空间模式研究的视野.  相似文献   

15.
ABSTRACT: The approximate streamflow partitioning method which uses daily rainfall and streamfiow data was applied in Coastal Plain, Coastal Flatwoods, and Southern Piedmont physiographic regions for estimation of the surface and subsurface flow components of total streainflow. Sizes of the watersheds ranged from 9.6 km2 to 1,030 km. Although the streamflow partitioning method was developed and tested on the Coastal Plain physiographic region, results indicate that the procedure can be applied to other physiographic regions where available data are limited to daily values. The effect of channelization on the partitioned flow components in the Coastal Plain and Coastal Flatwoods physiographic areas was also examined. While channelization was found to decrease the storm-time base, it had no significant effect on the relative percentages of the partitioned flow components.  相似文献   

16.
旅游流"井喷现象"是特殊时段旅游流时空分布的特殊现象之一,其时空分布规律研究有助于旅游目的地的科学管理参照.选取关中地区旅游资源丰富的西安、宝鸡、华山三地作为案例,建立"黄金周"客流周内波动指数R,周内分布偏度指数G,并使用相关分析和Pearson相关系数,分析陕西关中地区特殊时段内旅游流"井喷效应"的时空演变规律.结果显示,在假日制度时间约束下,旅游流呈现"井喷现象"显著,一级旅游目的地城市的旅游资源属性、周边地区旅游资源配置和区位交通状况共同影响着游客的空间选择行为,从而影响区域旅游流的时间和空间分布.  相似文献   

17.
基于1981—2010年云南省腾冲县基础气候的数据分析,建立了适用于腾冲县的旅游适宜度指数。结果显示,腾冲县全年的旅游适宜度指数变幅为16.5—24.0,表明全年的气候都适合旅游,其中每年的10月至次年的3月最适宜旅游,4—9月适宜旅游。此外,对合理开发气候旅游资源进行了有针对性的探讨,为地方旅游产业发展规划提供了气象依据。  相似文献   

18.
研究了新型复式潜流人工湿地对生活污水的净化效果。在不同水力负荷、季节、曝气方式等条件下经过小试试验,分析了该湿地对污染物净化效果的影响。结果表明,该系统出水水质稳定,达到《城镇污水处理厂污染物排放标准》(GB18918--2002)的一级A标准。在水力负荷184mm·d。条件下COD、NH,一N去除率最大分别可达87.2%、68.9%。冬季低温条件下对各类污染物去除率仍大于20%。正交试验分析得知,最佳运行条件是气温28.6℃、水力负荷0.184m3·m-2·d-1、水力停留时间2.4d。对比试验表明,采用预曝气方式对湿地净化效果明显优于厌氧处理。  相似文献   

19.
旅游景区解说设施研究   总被引:1,自引:0,他引:1  
为了更好地促进旅游信息的传播与交流、旅游地形象的宣传、旅游学术思想的交流与共享、旅游产品的促销、旅游服务的完善与提高等,对旅游景区解说设施的功能、类型、解说效果、相关因素、流程进行了深入研究,提出了旅游景区解说设施的4个功能、2大类型,比较分析了各类型旅游解说设施的解说效果、解说设施及其相关要素的循环关系,以及旅游景区解说设施的规划流程。  相似文献   

20.
    
Colombia is one of the most biodiverse countries in the world that has historically and is currently experiencing extensive deforestation and habitat fragmentation. Here we show how the most extensive region acting as a natural corridor between the Colombian Andes and Amazon biogeographical regions, the Picachos–Tinigua–Sierra de la Macarena–Chiribiquete megacorridor, is being eroded by large-scale agricultural expansion endangering the maintenance and connection of gene flow and biodiversity exchange. Several phylogenetic studies indicate that the complex dynamics between the Andean highlands and the Amazonian lowlands have strongly influenced the origin and maintenance of Neotropical biodiversity. We appeal for the attention of international conservation and governmental organizations to direct resources and promote projects focused on the preservation and sustainable management of this strategic Andes–Amazon bridge in both protected and unprotected areas. In the current postconflict era, Colombia has a unique opportunity to create a new social and economic paradigm based on long-term sustainably developed landscapes and more equitable sharing of wealth. We believe improved management and conservation efforts for the Picachos–Tinigua–Macarena–Chiribiquete megacorridor would demonstrate a collective will in helping to achieve this goal.  相似文献   

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