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501.
针对中国散裂中子源(CSNS)隧道内装置区永久点采用常规GPS三脚架观测模式中对中整平和仪器高量取精度差等问题,提出了一种高精度的仪器对中和超大仪器高的测量方案。该方案设计可微调的屋顶支架、目标半球垂准镜,实现了仪器的稳固安置和精确对中;改造GPS天线头支架适于放置目标球,以便采用激光跟踪仪获取高精度的超大仪器高;最后通过激光跟踪仪对隧道内6个装置区永久点重复两次测量,并与钢尺测量结果进行比较。结果表明,该方案可实现高30 m内仪器0.5 mm的对中精度和0.2 mm的量高精度,避免了卷尺测量尺长受拉伸影响的缺点,有效解决了CSNS装置永久点的精密对中和超大仪器高的获取,也为同类点位的对中和仪器高测量提供了借鉴和参考。 相似文献
502.
采用统计方法和数值模拟方法探讨人工影响后降水再分配和对局地降雨影响的可能性,统计结果表明:人工降雨影响了降水的自然分砷,在作业点下风方出现了二个影响区:一个是增雨区(出现在作业点下风方15~50km)另一个是减雨区(出现在作业点下风方90~150km)数值模拟结果表明,人工催化影响降水演变过程,而且改变了降水的分布,通过人为有意识的影响,有可能达到调控降水,减弱局地降雨的目的。 相似文献
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K. N. Bower T. W. Choularton M. W. Gallagher R. N. Colvile K. M. Beswick D. W. F. Inglis C. Bradbury B. G. Martinsson E. Swietlicki O. H. Berg S. -I. Cederfelt G. Frank J. Zhou J. N. Cape M. A. Sutton G. G. McFadyen C. Milford W. Birmili B. A. Yuskiewicz A. Wiedensohler F. Stratmann M. Wendisch A. Berner P. Ctyroky Z. Galambos S. H. Mesfin U. Dusek C. J. Dore D. S. Lee S. A. Pepler M. Bizjak B. Divjak 《Atmospheric Research》1999,50(3-4)
During March and April of 1995 a major international field project was conducted at the UMIST field station site on Great Dun Fell in Cumbria, Northern England. The hill cap cloud which frequently envelopes this site was used as a natural flow through reactor to examine the sensitivity of the cloud microphysics to the aerosol entering the cloud and also to investigate the effects of the cloud in changing the aerosol size distribution, chemical composition and associated optical properties. To investigate these processes, detailed measurements of the cloud water chemistry (including the chemistry of sulphur compounds, organic and inorganic oxidised nitrogen and ammonia), cloud microphysics and properties of the aerosol and trace gas concentrations upwind and downwind of the cap cloud were undertaken. It was found that the cloud droplet number was generally strongly correlated to aerosol number concentration, with up to 2000 activated droplets cm−3 being observed in the most polluted conditions. In such conditions it was inferred that hygroscopic organic compounds were important in the activation process. Often, the size distribution of the aerosol was substantially modified by the cloud processing, largely due to the aqueous phase oxidation of S(IV) to sulphate by hydrogen peroxide, but also through the uptake and fixing of gas phase nitric acid as nitrate, increasing the calculated optical scattering of the aerosol substantially (by up to 24%). New particle formation was also observed in the ultrafine aerosol mode (at about 5 nm) downwind of the cap cloud, particularly in conditions of low total aerosol surface area and in the presence of ammonia and HCl gases. This was seen to occur at night as well as during the day via a mechanism which is not yet understood. The implications of these results for parameterising aerosol growth in Global Climate Models are explored. 相似文献
504.
Energy‐compatible and spectrum‐compatible (ECSC) ground motion simulation using wavelet packets 下载免费PDF全文
A stochastic ground‐motion simulation and modification technique is developed to generate energy‐compatible and spectrum‐compatible (ECSC) synthetic motions through wavelet packet characterization and modification in both frequency and time domains. The ECSC method significantly advances traditional spectral matching approaches, because it generates ground motions that not only match the target spectral accelerations, but also match Arias intensity build‐up and significant durations. The great similarity between the ECSC simulated motions and the actual recorded motions is demonstrated through one‐to‐one comparison of a variety of intensity measures. Extensive numerical simulations were also performed to validate the performance of the ECSC ground motions through nonlinear analyses of elasto‐plastic oscillators. The ECSC method can be easily implemented in the generalized conditional intensity measure framework by directly simulating a set of motions following a targeted distribution of multiple intensity measures. Therefore, the ECSC method has great potential to be used in performance‐based earthquake design and analysis. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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市、县级人工影响天气轨道业务流程的研究 总被引:1,自引:0,他引:1
为推动气象业务技术体制改革,适应市、县级人工影响天气轨道建设,发挥市级指挥决策水平较高的优势,以提高作业指令的传达速度,减轻县级人影作业指挥的工作量,提出市级指挥中心直接指挥炮点作业等项新的市、县级人影轨道业务流程。该流程利用雷达指挥作业,使用GPRS技术传输作业指令,提高了地面增雨、防雹作业的科学性,保证了下达指令的实效和准确性,分工明确,减少了指挥环节,同时也加强了市级人影工作的管理功能。 相似文献
510.
许进 《广东海洋大学学报》2008,28(3)
研究了CO2改性水玻璃砂的热强度、高温强度和发气性,结果表明,随着粘结剂加入量的增加,热强度、高温强度和发气性增大;粘结剂种类不同,型砂的热强度、高温强度和发气性不同;其中,l#改性树脂改性水玻璃18#的热强度、高温强度均比普通水玻璃高,发气量则小于普通水玻璃;用扫描电镜分别观察了普通和改性水玻璃砂在加热温度为600℃、800℃、1000℃、1200℃时的高温炉内折断断口,解释了改性水玻璃砂比普通水玻璃砂高温强度高的原因。 相似文献