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161.
本文论述了热量测量原理,多户型热量表的软件、硬件设计思想和方法。建立了温度传感器、流量传感器的数学模型。经过在实验小区的试运行,证明其省电节能,管理方便,测量准确。 相似文献
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Ayodele Joseph Adesin Kanike Raghavendra Kumar Venkataraman Sivakumar Derek Griffith 《环境科学学报(英文版)》2014,26(12):2459-2474
The present study uses the data collected from Cimel Sunphotometer of Aerosol Robotic Network(AERONET) for the period from January to December, 2012 over an urban site,Pretoria(PTR; 25.75°S, 28.28°E, 1449 m above sea level), South Africa. We found that monthly mean aerosol optical depth(AOD, τa) exhibits two maxima that occurred in summer(February) and winter(August) having values of 0.36 ± 0.19 and 0.25 ± 0.14,respectively, high-to-moderate values in spring and thereafter, decreases from autumn with a minima in early winter(June) 0.12 ± 0.07. The Angstrom exponents(α440–870) likewise,have its peak in summer(January) 1.70 ± 0.21 and lowest in early winter(June) 1.38 ± 0.26,while the columnar water vapor(CWV) followed AOD pattern with high values(summer) at the beginning of the year(February, 2.10 ± 0.37 cm) and low values(winter) in the middle of the year(July, 0.66 ± 0.21 cm). The volume size distribution(VSD) in the fine-mode is higher in the summer and spring seasons, whereas in the coarse mode the VSD is higher in the winter and lower in the summer due to the hygroscopic growth of aerosol particles.The single scattering albedo(SSA) ranged from 0.85 to 0.96 at 440 nm over PTR for the entire study period. The averaged aerosol radiative forcing(ARF) computed using SBDART model at the top of the atmosphere(TOA) was- 8.78 ± 3.1 W/m2, while at the surface it was- 25.69 ± 8.1 W/m2 leading to an atmospheric forcing of + 16.91 ± 6.8 W/m2, indicating significant heating of the atmosphere with a mean of 0.47 K/day. 相似文献
163.
To understand the short-term effects of forest gap by human harvesting on soil available nutrient in Pinus massoniana plantations, the variations of soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3-N) concentrations in the gap center and gap edge during growing season were observed in seven gaps of different size (Gl: 100 m2; G2:225 m2; G3:400 m2; G4:625 m2; G5:900 m2; G6:1225 m2; G7:1600 m2) and pure understory of a 39-year-old masson pine plantation in a hilly area of the upper reaches of Yangtze River. The results showed that in the early stage of gap formation, the gap size had significant effect on NH4+-N, the season changes on NP3--N, and the interaction effect of gap size and seasonal variation on NH4+-N and NO3--N. The difference of NH4+-N and NO3--N between the gap center and gap edge was not significant. (I) The NH4+-N content was 4.30-11.99 mg kg-1, and NO3--N content was 2.57-10.81 mg kg-1. There was no obvious difference in NH4+-N and N03--N among gaps of different size in early or late growing seasons, when both increased first and decreased afterwards in the middle of growing season. The gaps of 100∼400 m2 area had a higher content of available nitrogen. (2) The seasonal dynamic differed between NH4+-N and NO3--N, with the former lower in middle growing season whereas the latter higher in the middle growing season but lower in the end of growing season. The soil NH4+-N was higher than NO3- -N in the early and late periods, but lower in the middle period. (3) The soil NH4+-N and NO3--N in parts of gaps were lower than understory in the early and late growing season. (4) Correlation analyses showed that NH4+-N had significant positive correlation with microbial biomass nitrogen (MBN), and NO3--N with soil temperature, MBN and organic matter. But the impact of soil water content on available nitrogen was not significant. These results suggested that soil temperature and microbial activity variation caused by gap harvesting are the main factors affecting soil available nitrogen content of Pinus massoniana plantations. 相似文献
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特大型现代化矿井高压漏电保护系统的研制 总被引:2,自引:0,他引:2
本文介绍一特大型现代化矿井的高压漏电保护系统。该保护系统能集中监护地面变电所6段母线64路馈出线、井下中央变电所8段母线48路馈出线,以及井筒中的四对并联下井电缆;具有自动选线、选相、声光报警、数字显示、自动记录及自检演示等功能;还能区分永久性漏电和瞬间性漏电。 相似文献