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A pyritic coal waste, an alkaline gasification ash, and an alkaline fly ash were leached continuously under saturated conditions for six months at 20 deg C. Waste samples were removed after three and six months of leaching. These ...
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A pyritic coal waste, an alkaline gasification ash, and an alkaline fly ash were leached continuously under saturated conditions for six months at 20 deg C. Waste samples were removed after three and six months of leaching. These samples, in addition to a sample with no leaching, were used to make up equilibrium solutions. The leaching data showed a continuous release of soluble species under low temperature anaerobic conditions. As leaching progressed, relatively soluble sulfates, carbonates and amorphous phases were removed leaving the control of cation and anion activities to less soluble primary and secondary minerals. Data from the equilibrium solutions were used to calculate the saturation index for common secondary minerals that could form in the waste/water system. The saturation index data show that the mineral phases that control the equilibrium leachate chemistry will change as leaching progresses. All of the data generated in this study suggest that the long-term geochemistry of a waste/water system will vary with time depending upon the magnitude and duration of leaching and the occurrence of equilibrium or nonequilibrium conditions. (ERA citation 11:019031)
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This guide is intended to help general aviation (GA) pilots, especially those with relatively little weather-flying experience, develop skills in obtaining appropriate weather information, interpreting the data in the context of a...
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This guide is intended to help general aviation (GA) pilots, especially those with relatively little weather-flying experience, develop skills in obtaining appropriate weather information, interpreting the data in the context of a specific flight, and applying the information and analysis to make safe weather flying decisions.
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The Situation Climatic Briefs present narrative climatologies of a country or geographical area by season. They describe weather factors that could significantly affect military operations. Each situation climatic brief presents a...
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The Situation Climatic Briefs present narrative climatologies of a country or geographical area by season. They describe weather factors that could significantly affect military operations. Each situation climatic brief presents a general overview of the climate and descriptions of flying weather, reconnaissance weather, terminal weather, exposure weather, paradrop weather, and astronomical data. Some briefs also contain descriptions of seastate, extreme weather, port conditions, or beach conditions.
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A laboratory study was made to establish influences of elevated batching and curing temperatures on strength properties of concrete. The study included three mix temperatures and two cycles of curing conditions which simulated hot...
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A laboratory study was made to establish influences of elevated batching and curing temperatures on strength properties of concrete. The study included three mix temperatures and two cycles of curing conditions which simulated hot weather concrete in Florida. The variables included cement Types I, II, III, fly ash, and two dosage rates for water-reducer retarder. The data indicate that concrete placed at 32C (90F) gave approximately four percent higher compressive strength than concrete placed at 22C (75F) and 41C (105F) for the simulated hot weather cycles. One and one-half times the recommended dosage rate of a water-reducer retarder produced higher concrete compressive strength than the concrete with normal dosage rate.
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The interpretation of surface and aircraft measurements of cloud properties taken during field programs must take into account the large-scale cloud and meteorological conditions. Cloud properties are also required at scales beyon...
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The interpretation of surface and aircraft measurements of cloud properties taken during field programs must take into account the large-scale cloud and meteorological conditions. Cloud properties are also required at scales beyond the point and line data taken from ground and aircraft platforms. Satellite data can provide a quantitative description of these large-scale cloud properties. When derived from geostationary satellite data, the cloud fields constitute a unique source for evaluating the development and demise of a cloud system. Satellites, however, can only see the tops of clouds, so that cloud layers below the uppermost cloud deck may remain undetected resulting in a incomplete depiction of the cloud system. Some multilayer clouds are amenable to detection from satellites. Many, especially in midlatitude cyclonic systems, can only be observed from the surface. A combination of surface and satellite cloud observations should be the most complete quantification of large-scale cloudiness if there are sufficient surface measurements. During the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment Phase 2 (FIRE-2) Cirrus Intensive Field Observation (IFO) period (November 13 - December 7, 1991) conducted at Coffeyville, Kansas, cirrus observations were taken in a variety of conditions. The IFO area was selected for a variety of reasons including the relatively dense network of surface weather stations and special surface instrumentation sites. Thus, the FIRE-2 IFO presents an excellent opportunity to combine cloud observations from surface and satellite observations. This paper presents an analysis of cloud properties on a mesoscale grid using satellite cloud property retrievals, surface observer data, and rawinsonde temperature and humidity profiles.
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Findings from a field study on Hot Weather Concreting are presented comparing various combinations of cementitious material, chemical admixture dosage rates, concrete placing temperatures and environmental conditions to determine ...
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Findings from a field study on Hot Weather Concreting are presented comparing various combinations of cementitious material, chemical admixture dosage rates, concrete placing temperatures and environmental conditions to determine their effect on concrete temperature development and strength properties of concrete used in bridge deck construction. Also described is an instrumentation system for measuring and recording concrete temperature development in a structure and a weather station for monitoring environmental conditions.
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This report, which summarizes flying weather in Honduras, El Salvador, Nicaragua, and Costa Rica, was prepared from interviews with highly experienced civil and military pilots and meteorologists in Honduras and Costa Rica. Flying...
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This report, which summarizes flying weather in Honduras, El Salvador, Nicaragua, and Costa Rica, was prepared from interviews with highly experienced civil and military pilots and meteorologists in Honduras and Costa Rica. Flying weather in defined areas is described for each of the climatological seasons--seasons that do not necessarily match calendar seasons or North American temperate zone seasons. Keywords: Climate; Central America; Aviation Weather; Climatology; Cloud; Ceiling; Visibility; Wind; Precipitation; Fog; Haze: Smoke; Temporale; Mountain Wave; Military Meteorology.
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The study investigated the durability of high strength concrete at levels of 8,10, and 12 ksi both with and without entrained air. Variables included air content, fly ash content, coarse aggregate type, cement and silica fume cont...
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The study investigated the durability of high strength concrete at levels of 8,10, and 12 ksi both with and without entrained air. Variables included air content, fly ash content, coarse aggregate type, cement and silica fume content, and type and length of curing. Testing performed included compressive strength, freeze-thaw resistance, rapid chloride ion permeability, deicer scaling resistance, chloride ion penetration, and microscopial air-void analysis. Testing indicates the need for entrained air in high strength concrete in order to render it freeze-thaw resistant.
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Presented is a guide to mountain flying in Colorado. The hazards of winter flying are described, as are methods for avoiding them. Airports in Colorado's ski region are discussed. Maps are provided. Arrivals and departures in moun...
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Presented is a guide to mountain flying in Colorado. The hazards of winter flying are described, as are methods for avoiding them. Airports in Colorado's ski region are discussed. Maps are provided. Arrivals and departures in mountain airports in general are reviewed.
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The report includes an extensive literature review and laboratory investigations for selected physical properties of concrete mixtures used in the construction of continuously reinforced concrete pavement (CRCP). Nine test paramet...
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The report includes an extensive literature review and laboratory investigations for selected physical properties of concrete mixtures used in the construction of continuously reinforced concrete pavement (CRCP). Nine test parameters were investigated in the study: temperature, relative humidity, and wind speed; concrete temperature, type of aggregate, amount of mixing water and replacement of fly ash; and mixing time and consolidation effort. A total of 116 tests were performed in three categories: strength tests such as compressive, pullout, flexural and modified compressive strength; volume and weight change tests such as shrinkage and weight loss of bar specimen, moisture content, and loss measurements of cube specimen; and other tests such as time of setting and abrasion resistance. An evaporometer developed by SDHPT was used to measure evaporation rates for several environmental conditions, and to congregate the environmental factors into one variable.
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