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101.
科学合理的设计理论是工程安全性和经济性的保障,现场监测是确保工程安全和质量最有效的手段。本文以提高刚性桩复合地基工程的安全性为目的,围绕关乎建筑物安全的“沉降量”等参数指标,从设计理论与试验监测两个方面开展研究。本文完善了刚性桩复合地基的设计理论,通过现场监测试验取得了第一手的数据资料,可作为今后类似工程的设计和施工参考。本研究为进一步提高刚性桩复合地基的安全性提供了理论和实践保障。 相似文献
102.
纳米铝粉对烟火药剂热安全性影响研究 总被引:1,自引:1,他引:0
为研究铝粉纳米化后对烟火药剂性能的影响,本文将普通铝粉和纳米铝粉分别与氯酸钾、硫粉按照零氧平衡的同一配比(17%AL+63%KClO3+20%S)配成的烟火药剂进行ARC热分析对比试验发现,含纳米铝粉的烟火药剂热分解的初始反应温度降低,反应到达最大温升速率所需的时间延长,反应所能达到的最高压力降低。这说明纳米铝粉的加入在加速其反应进程的同时,可有效地降低其反应的激烈程度和危险性,即铝粉纳米化后可以有效的改善烟火药剂的性能,提高其安全性。 相似文献
103.
Oxidative stress and DNA damages induced by cadmium accumulation 总被引:22,自引:0,他引:22
Experimental evidence shows that cadmium (Cd) could induce oxidative stress and then causes DNA damage in animal cells, however, whether such effect exists in plants is still unclear. In the present study, Vicia faba plants was exposed to 5 and 10 mg/L Cd for 4 d to investigate the distribution of Cd in plant, the metal effects on the cell lipids, antioxidative enzymes and DNA damages in leaves. Cd induced an increase in Cd concentrations in plants. An enhanced level of lipid peroxidation in leaves and an enhanced concentration of H2O2 in root tissues suggested that Cd caused oxidative stress in Vicia faba. Compared with control, Cd-induced enhancement in superoxide dismutase activity was significant at 5 mg/L than at 10 mg/kg in leaves, by contrast, catalase and peroxidaseactivities were significantly suppressed by Cd addition. DNA damage was detected by neutral/neutral, alkaline/neutral and alkaline/alkaline Comet assay. Increased levels of DNA damages induced by Cd occurred with reference to oxidative stress in leaves, therefore, oxidative stress induced by Cd accumulation in plants contributed to DNA damages and was possibly an important mechanism of Cd-phytotoxicity in Vicia faba plants. 相似文献
104.
通过对重庆地区村镇住宅的实地调研和村镇典型住宅温湿度连续监测,获得了重庆地区村镇住宅的主要围护结构形式以及典型房屋2010年1~9月的室内热湿环境状况,并利用重庆地区自然通风适应性热舒适性评价模型进行了分析。结果表明:现有墙体热工性能最好的是180红砖内外水泥砂浆抹灰外贴瓷砖形式,测试房屋冬季室内最低温度为83℃,最高相对湿度为962%,夏季室内最高温度为344℃,最高相对湿度为99%。监测数据中相对湿度大于70%的时数占总测试时数的93%。住宅围护结构的冷热抵御能力和湿舒适湿卫生条件都很差。采暖季节室内达到舒适只有2 d,空调季节有58 d,村镇地区围护结构冬季保温要求比夏季隔热显得更为突出 相似文献
105.
106.
热真空试验是航天器研制过程中非常重要的一项试验,作为满足热真空试验必不可少的工具,好的热真空试验系统可以保证试验件在不失真的情况下试验,使试验受控,而热真空试验系统温度均匀度不好,会造成过试验或欠试验的产生。文中以某型热真空试验设备为例,通过试验研究分析其温度均匀度,可以提高热真空试验的精度。 相似文献
107.
Benchmarking Optical/Thermal Satellite Imagery for Estimating Evapotranspiration and Soil Moisture in Decision Support Tools
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Jan M.H. Hendrickx Richard G. Allen Al Brower Aaron R. Byrd Sung‐ho Hong Fred L. Ogden Nawa Raj Pradhan Clarence W. Robison David Toll Ricardo Trezza Todd G. Umstot John L. Wilson 《Journal of the American Water Resources Association》2016,52(1):89-119
Generally, one expects evapotranspiration (ET) maps derived from optical/thermal Landsat and MODIS satellite imagery to improve decision support tools and lead to superior decisions regarding water resources management. However, there is lack of supportive evidence to accept or reject this expectation. We “benchmark” three existing hydrologic decision support tools with the following benchmarks: annual ET for the ET Toolbox developed by the United States Bureau of Reclamation, predicted rainfall‐runoff hydrographs for the Gridded Surface/Subsurface Hydrologic Analysis model developed by the U.S. Army Corps of Engineers, and the average annual groundwater recharge for the Distributed Parameter Watershed Model used by Daniel B. Stephens & Associates. The conclusion of this benchmark study is that the use of NASA/USGS optical/thermal satellite imagery can considerably improve hydrologic decision support tools compared to their traditional implementations. The benefits of improved decision making, resulting from more accurate results of hydrologic support systems using optical/thermal satellite imagery, should substantially exceed the costs for acquiring such imagery and implementing the remote sensing algorithms. In fact, the value of reduced error in estimating average annual groundwater recharge in the San Gabriel Mountains, California alone, in terms of value of water, may be as large as $1 billion, more than sufficient to pay for one new Landsat satellite. 相似文献
108.
Zhao Xuxin Ji Jie Sun Hongyuan Ma Rui Wu Qixing 《International Journal of Green Energy》2016,13(3):229-240
The heat-pipe solar water heating (HP-SWH) system and the heat-pipe photovoltaic/thermal (HP-PV/T) system are two practical solar systems, both of which use heat pipes to transfer heat. By selecting appropriate working fluid of the heat-pipes, these systems can be used in the cold region without being frozen. However, performances of these two solar systems are different because the HP-PV/T system can simultaneously provide electricity and heat, whereas the HP-SWH system provides heat only. In order to understand these two systems, this work presents a mathematical model for each system to study their one-day and annual performances. One-day simulation results showed that the HP-SWH system obtained more thermal energy and total energy than the HP-PV/T system while the HP-PV/T system achieved higher exergy efficiency than the HP-SWH system. Annual simulation results indicated that the HP-SWH system can heat the water to the available temperature (45°C) solely by solar energy for more than 121 days per year in typical climate regions of China, Hong Kong, Lhasa, and Beijing, while the HP-PV/T system can only work for not more than 102 days. The HP-PV/T system, however, can provide an additional electricity output of 73.019 kWh/m2, 129.472 kWh/m2, and 90.309 kWh/m2 per unit collector area in the three regions, respectively. 相似文献
109.
Mejdi Jeguirim Lionel Limousy Eric Fossard 《International Journal of Green Energy》2016,13(6):608-615
Spent coffee grounds (SCG) and coffee husks (CH) were evaluated as biofuels, after densification, for energy production. CH represent a specific problem for the coffee industry due to a low calorific value, high ash content, and a very low bulk density. Hence, the energetic potential of SCG (95 wt%)/CH (5 wt%) blend and pure SCG (100%) were examined. The blend of SCG and CH was limited to 5 wt% of CH because of the low bulk density of CH. Therefore, physicochemical and energetic characterizations of the produced pellets were performed. Thermogravimetric analyses were performed under nitrogen and air atmospheres to evaluate the CH behavior in the blend. Characterization study shows that both produced pellets could reach the French Agropellets standard (AQI). Thermal degradation showed that the mean reactivity of the SCG/HC pellets was higher than pure SCG. Then, combustion experiments were performed in a domestic combustor, after modification of the boiler power in order to improve its energetic performances. The presence of CH led to a rise of CO, NOx, VOC’s, and particle emissions. Nevertheless, the performances of the biofuels are almost in agreement the NF EN 12809 standard. 相似文献
110.
A combined photovoltaic–thermal (PV/t) panel is proposed to produce simultaneously electricity and heat from one integrated unit. The unit utilizes effectively the solar energy through achieving higher PV electrical efficiency and using the thermal energy for heating applications. To predict the performance of the PV/t at a given environmental conditions, a transient mathematical model was developed. The model was integrated in a heating application for a typical office space in the city of Beirut to provide the office needs for electricity, heating during winter season, and dehumidification and evaporative cooling during the summer season. To minimize the yearly office energy (electrical and heat) needs, the PV/t panel cooling air flow rate and the dehumidification regeneration temperature were determined for opimal unit operation. Thermal energy savings of up to 85% in winter and 71% in summer were achived compared to conventional systems at a payback period of 8 years for the panels. 相似文献