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1.
系统采用双膜盒作为水压的敏感元件,将光纤位移传感器用于检测膜盒随水压变化引起的形变.系统的信号处理电路包括光信号前置放大电路、带通滤波电路、真有效值转换电路,采用16位超低功耗的混合信号处理器MSP430作为数据处理模块.实验结果表明:系统可以测量0～181.0mm的水面液位变化,分辨率为0.7mm.增加膜盒的数量可以提高系统的分辨率. 相似文献
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光电探测系统在光度测量及光谱检测领域应用广泛,是检测的核心部件.光电探测系统的响应时间反映了该系统能够探测的极限,对其进行准确的测量在实际应用中十分必要.本文展示了一种能够准确测量光电探测系统响应时间的方法,以常用的可调谐二极管激光器（波长为763 nm）为光源,采用方波信号调谐光源输出,测量了系统的响应时间.结果显示,示波器内电阻对系统的响应时间存在影响,当电阻为50 Ω时,探测系统的响应时间为4.5 μs.降低电阻值,可以进一步缩短响应时间. 相似文献
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搭建了一套以中心输出波长为808.5 nm的半导体激光端面泵浦Nd:YVO4激光晶体产生1 064 nm红外激光,然后以腔内KTP晶体倍频的方法将红外激光倍频为532 nm绿光激光的固体激光实验系统,研究了808.5 nm的泵浦半导体激光的输出功率与注入电流的关系及与532 nm绿光输出功率的关系,以及KTP倍频晶体的相位匹角、泵浦光的聚焦位置和固体激光器的腔长等因素对532 nm绿光输出功率的影响.实验结果表明:提高泵浦半导体激光的泵浦功率、缩短固体激光器的腔长、将泵浦光聚焦到Nd:YVO4晶体内部以及正确选择KTP晶体的相位匹配角能够提高532 nm绿光的输出功率. 相似文献
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以近红外可调谐半导体激光器为光源,以反射率为９９７％左右的平凹镜组成的稳定光学谐振腔作吸收池,构建起一套腔增强吸收光谱（ＣＥＡＳ）系统;以二氧化碳气体（ＣＯ２）、一氧化碳气体（ＣＯ）、甲烷气体（ＣＨ４）以及一氧化碳和二氧化碳的混合气体为样品,利用分子在近红外波段的特征吸收,研究了在近红外波段用ＣＥＡＳ技术探测ＣＯ、ＣＯ２、ＣＨ４ 等气体的可行性;同时也对基于可调谐半导体激光器的ＣＥＡＳ系统中激光器的波长定标、谐振腔（吸收池）的透射特征等做了研究,获得了ＣＯ、ＣＯ２、ＣＨ４以及ＣＯ和ＣＯ２ 混合气体的特征吸收谱,最后对ＣＥＡＳ技术在定量测量方面的能力做了研究．研究结果表明,ＣＥＡＳ技术的探测灵敏度可达５６８７×１０－７ｃｍ－１,是一种装置简单、操作方便、灵敏度高、稳定性好的定量吸收光谱技术． 相似文献
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提出了一种实验上可行的,通过光学谐振腔内多通道参量下转换过程直接产生多色连续变量对纠缠频率梳的方案,腔内增益介质为周期极化的准相位匹配的钽酸锂(LiTaO3)一维光学超晶格.通过连续变量纠缠判据证明了每个通道中产生的每对参量光之间是相互纠缠的.讨论了对纠缠频率梳的纠缠特性随系统参数的变化.此方案在量子通信网络中有着一定的应用前景. 相似文献
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目前的商用偏振分析仪检测速率较低,因此在检测光纤通信中高速信号的偏振态时,需要自行搭建测量系统并结合高速实时数字示波器使用.此时,系统定标就显得尤为重要,定标方法也将直接影响测量的准确性.针对光纤型高速偏振态检测系统提出了定标方法,先通过Mueller矩阵算法对其进行了理论分析,进而通过实验证明了该定标方法准确可行,测量误差水平小于±3%. 相似文献
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为实现微热弯成形系统中微位移的高精度测量,构建了微位移计算机视觉测量系统.应用Matlab编写摄像机标定程序并计算摄像机的内外参数,利用OpenCV对被测对象的图像进行灰度化、二值化和Canny边缘提取,采用序贯相似性检测算法(SSDA)进行模板匹配,实现了热弯曲成形过程中模具与工件位置微位移的实时在线检测.实验结果表明,该系统对微位移的测量具有操作简单、高效的特点. 相似文献
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针对考虑传感器故障的柔性航天器姿态系统,提出了一种主动容错控制方法.首先,通过对测量输出进行滤波,将传感器故障转化为执行器故障形式;接着,设计一个基于未知输入观测器的自适应故障估计观测器,对未知故障进行辨识,同时,采用了一个故障检测观测器,对故障的发生进行检测;然后,利用故障估计信号对系统输出进行调节,结合自适应积分滑模和线性矩阵不等式技术设计输出反馈容错控制器;最后,对所设计的主动容错控制方法进行仿真,验证了所提方法的有效性. 相似文献
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Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter. 相似文献
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Fei LIU Chen XING Jinbao LI Bin WANG Jing CHAI Chaochao GAO Gang HUANG Jian LIU Deliang CHEN 《大气科学进展》2020,37(7):663-670
正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment. 相似文献
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The moving-window correlation analysis was applied to investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the synchronous autumn precipitation in Huaxi region, based on the daily precipitation, sea surface temperature (SST) and atmospheric circulation data from 1960 to 2012. The correlation curves of IOD and the early modulation of Huaxi region’s autumn precipitation indicated a mutational site appeared in the 1970s. During 1960 to 1979, when the IOD was in positive phase in autumn, the circulations changed from a “W” shape to an ”M” shape at 500 hPa in Asia middle-high latitude region. Cold flux got into the Sichuan province with Northwest flow, the positive anomaly of the water vapor flux transported from Western Pacific to Huaxi region strengthened, caused precipitation increase in east Huaxi region. During 1980 to 1999, when the IOD in autumn was positive phase, the atmospheric circulation presented a “W” shape at 500 hPa, the positive anomaly of the water vapor flux transported from Bay of Bengal to Huaxi region strengthened, caused precipitation ascend in west Huaxi region. In summary, the Indian Ocean changed from cold phase to warm phase since the 1970s, caused the instability of the inter-annual relationship between the IOD and the autumn rainfall in Huaxi region. 相似文献
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Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration. 相似文献
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The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o. 相似文献
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基于最新的GTAP8 (Global Trade Analysis Project）数据库,使用投入产出法,分析了2004年到2007年全球贸易变化下南北集团贸易隐含碳变化及对全球碳排放的影响。结果显示,随着发展中国家进出口规模扩张,全球贸易隐含碳流向的重心逐渐向发展中国家转移。2004年到2007年,发达国家高端设备制造业和服务业出口以及发展中国家资源、能源密集型行业及中低端制造业出口的趋势加强,该过程的生产转移导致全球碳排放增长4.15亿t,占研究时段全球贸易隐含碳增量的63%。未来发展中国家的出口隐含碳比重还将进一步提高。贸易变化带来的南北集团隐含碳流动变化对全球应对气候变化行动的影响日益突出,发达国家对此负有重要责任。 相似文献
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Hourly outgoing longwave radiation(OLR) from the geostationary satellite Communication Oceanography Meteorological Satellite(COMS) has been retrieved since June 2010. The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels. This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm(OLR12.0using the 12.0 μm channel) and three multiple-channel algorithms(OLR10.8+12.0using the 10.8 and 12.0 μm channels; OLR6.7+10.8using the 6.7 and 10.8 μm channels; and OLR All using the 6.7, 10.8, and 12.0 μm channels). The COMS OLRs from these algorithms were validated with direct measurements of OLR from a broadband radiometer of the Clouds and Earth's Radiant Energy System(CERES) over the full COMS field of view [roughly(50°S–50°N, 70°–170°E)] during April 2011.Validation results show that the root-mean-square errors of COMS OLRs are 5–7 W m-2, which indicates good agreement with CERES OLR over the vast domain. OLR6.7+10.8and OLR All have much smaller errors(～ 6 W m-2) than OLR12.0and OLR10.8+12.0(～ 8 W m-2). Moreover, the small errors of OLR6.7+10.8and OLR All are systematic and can be readily reduced through additional mean bias correction and/or radiance calibration. These results indicate a noteworthy role of the6.7 μm water vapor absorption channel in improving the accuracy of the OLRs. The dependence of the accuracy of COMS OLRs on various surface, atmospheric, and observational conditions is also discussed. 相似文献
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Analysis of Atmospheric Boundary Layer Height Characteristics over the Arctic Ocean Using the Aircraft and GPS Soundings 
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下载免费PDF全文 正ERRATUM to: Atmospheric and Oceanic Science Letters, 4(2011), 124-130 On page 126 of the printed edition (Issue 2, Volume 4), Fig. 2 was a wrong figure because the contact author made mistake giving the wrong one. The corrected edition has been updated on our website. The editorial office is sincerely sorry for any 相似文献
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《大气科学进展》2014,(6)
正AN Junling;see LI Ying et al.;(5),1221—1232AN Junling;see QU Yu et al.;(4),787-800AN Junling;see WANG Feng et al.;(6),1331-1342Ania POLOMSKA-HARLICK;see Jieshun ZHU et al.;(4),743-754Baek-Min KIM;see Seong-Joong KIM et al.;(4),863-878BAI Tao;see LI Gang et al.;(1),66-84BAO Qing;see YANG Jing et al.;(5),1147—1156BEI Naifang; 相似文献