The Durham/ESO SLODAR optical turbulence profiler

An instrument for monitoring of the vertical profile of atmospheric optical turbulence strength, employing the Slope Detection and Ranging (SLODAR) double star technique applied to a small telescope, has been developed by Durham University and the European South Observatory. The system has been deployed at the Cerro Paranal observatory in Chile for statistical characterization of the site. The instrument is configured to sample the turbulence at altitudes below 1.5 km with a vertical resolution of approximately 170 m. The system also functions as a general-purpose seeing monitor, measuring the integrated optical turbulence strength for the whole atmosphere, and hence the seeing width. We give technical details of the prototype and present data to characterize its performance. Comparisons with contemporaneous measurements from a differential image motion monitor (DIMM) and a multi-aperture scintillation sensor (MASS) are discussed. Statistical results for the optical turbulence profile at the Paranal site are presented. We find that, in the median case, 49 per cent of the total optical turbulence strength is associated with the surface layer (below 100 m), 35 per cent with the 'free atmosphere' (above 1500 m) and 16 per cent with the intermediate altitudes (100–1500 m).     

Development of the Automatic Seeing Monitor for the Site Testing of Dome A

The Antarctic site-testing campaigns have shown that Dome C is an excellent astronomical site on the earth, it is better than any of existing mid-latitude astronomical sites in the world, because of its cold and dry weather, low infrared background radiation, continuously observable time as long as 3–4 months, clear and highly transparent atmosphere, low wind speed, and the absence of dust and light pollution. And in the international astronomical community it is generally believed that Dome A with a higher altitude may be better than Dome C as a potential excellent astronomical site. In the past 3 years, although held by the Center for Antarctic Astronomy of Chinese Academy of Sciences, the site testing at Dome A has preliminarily con?rmed the many advantages of Dome A as an excellent astronomical site, but the data about the atmospheric seeing, which is an important parameter for assessing the site quality for optical observations, have not been obtained until now. Hence, on the basis of a commercial telescope with the diameter of 35 cm, we have made the hardware reformation and software development to have it operate as a DIMM (Differential Image Motion Monitor), which can simultaneously monitor both the seeing and isoplanatic angle at Dome A automatically. At present this instrument has been shipped to Antarctica by the “Xuelong” exploration ship, and will be installed at Dome A, and begin to work in early 2011. Before the shipment, by through the comparative measurements together with an existing seeing monitor at the Xinglong astronomical station, the software, hardware, as well as the installation and adjustment of the instrument, are further veri?ed by testing.     

埃文斯目视日晕光度计测量原理研究

埃文斯目视日晕光度计（Evans Visual Sky Photometer,EVSP）是应用于日冕仪选址的重要仪器,从20世纪40年代一直使用至今,它为现代日晕光度计的定标提供了参考标准。通过使用云南天文台现存的一架EVSP研究了它的工作原理,并重点介绍了所利用的简易定标方法。给出了国际现有的多台EVSP日晕亮度定标曲线。由于EVSP内部光学元件反射率和透过率,以及中性渐变光楔的光学密度等存在未知的时间缓变特点,因此利用这种新定标手段可以高效经济地获得各自的定标曲线。     

LOLAS: an optical turbulence profiler in the atmospheric boundary layer with extreme altitude resolution

We report the development and first results of an instrument called Low Layer SCIDAR (Scintillation Detection and Ranging) (LOLAS) which is aimed at the measurement of optical-turbulence profiles in the atmospheric boundary layer with high altitude resolution. The method is based on the Generalized SCIDAR (GS) concept, but unlike the GS instruments which need a 1-m or larger telescope, LOLAS is implemented on a dedicated 40-cm telescope, making it an independent instrument. The system is designed for widely separated double-star targets, which enables the high altitude resolution. Using a 200-arcsec-separation double star, we have obtained turbulence profiles with unprecedented 12-m resolution. The system incorporates necessary novel algorithms for autoguiding, autofocus and image stabilization. The results presented here were obtained at Mauna Kea Observatory. They show LOLAS capabilities but cannot be considered as representative of the site. A forthcoming paper will be devoted to the site characterization. The instrument was built as part of the Ground Layer Turbulence Monitoring Campaign on Mauna Kea for Gemini Observatory.     

川江中坝遗址5000年来洪水事件研究

川江中坝遗址自然地层与文化层测年、粒度分析及其与长江沿岸现代洪积物粒度分析对比研究表明,中坝遗址自然沉积层为多期洪水泛滥成因.文化层中大量破碎陶罐、瓦片以及窑址的发现,结合实地调查表明当时遗址区主要以制盐为主.一定数量未燃尽的段木的发现,表明人们为制盐或烧制陶器而砍伐树木,导致水土流失与生态恶化,水土流失导致河床淤积,储水量减少,从而加重洪灾程度、加剧河床演变.频繁的洪水泛滥使研究区河床发生较大变化,使遗址从河岸孤立出去,成为河中心的一个孤岛.     

日照黄海海域冷水团勘察工程施工工艺探究

日照万泽丰渔业有限公司黄海冷水团优质鱼类绿色养殖项目是山东省首批公布的新旧动能转换重大项目,规划海域面积20 km2。工程勘察是工程建设项目首先开展的基础性工作,是项目选址、设计和施工的重要依据。本文通过有效盘活有限资源,科学论证、严谨施工,创新钻探船改造、重力导向装置实现深海套管安放,成功实施了该项目的工程勘察工作,为远海深水勘察施工提供了经验。     

成层场地基本周期简化计算方法研究

从波动问题物理本质出发,提取阻抗比和周期比作为表征不同土层条件下场地周期变化规律的基本特征量。提出了子层周期贡献系数的概念,并指出其可由阻抗比和周期比唯一确定,建立了周期贡献系数与阻抗比和周期比一般关系。采用子层周期加权累加方式形成一套简单实用且具有明确物理意义的成层场地基本周期估算方法,以传递函数法结果为标准,就240种工况算例与现有简化方法进行对比,给出各方法偏差分析和适用性评价。主要结论为:阻抗比和周期比作为场地周期研究的基本特征量,结果具有完备性;传统法无法反映土层结构对场地周期的影响,对最普遍的渐硬型场地,偏差也有可能达到40%以上,对存在极端软夹层情况其偏差极易大于20%;Hadjian法精度明显优于传统法,但方法和参数本身缺乏明确的物理意义;新方法在一般和极端两种情况下最大偏差均不超过8%,偏差小于5%和2%工况数占比分别达到85%和60%以上,高于Hadjian简化法,可以在实际工程中推广应用。     

典型铬渣污染场地铬污染特征研究

选取西南岩溶区某傍河铬渣堆场为研究对象,对场地不同位置与深度的土壤及地下水样品进行采集,通过数理统计对Cr在场地中的空间分布特征以及场地对地下水的影响进行了分析。结果表明:土壤中总Cr浓度的水平分布具有差异性,表层土壤Cr浓度由上游到下游呈明显降低趋势,变化率为3.59;深层饱水带土壤中总Cr浓度分布受到地下水流场的影响,场地下游土壤铬浓度明显高于上游;杂填土垂向剖面的铬浓度分布不同于坡残积红黏土,杂填土中铬浓度随着深度的增加而增加,浓度与土壤深度的关系可用y=63.88ln（x）-75.221来表示;而在红黏土中剖面中,铬大量聚集在土壤表层,后随着深度的增加铬浓度逐渐降低,接近基岩面有升高趋势;场地地下水中Cr（Ⅵ）的浓度受深层土壤中总Cr浓度的影响,两者呈正相关。      

旧石器遗址强烈化学风化沉积物细粒混合矿物的光释光信号特征及其测年应用

从湖南省北部赤山岛枫树嘴旧石器遗址剖面第2、第3和第4考古层位采集的3个沉积物样品中提取的细粒混合矿物,尝试对其红外释光(IRSL)信号进行研究。实验表明,虽然长石IRSL信号很弱,但仍可以测得信噪比足够高的红外激发后高温红外激发释光(post-IR IRSL)信号。与此同时,样品存在明显的红外激发后蓝光释光(post-IR OSL)信号,并且样品的IRSL与post-IR OSL信号均以快组分为主,这为该地区沉积物利用长石光释光信号定年提供了新的可能。鉴于长石IRSL信号较弱,根据剂量恢复实验结果,本研究采用post-IR IRSL SAR法(50℃红外激发后270℃高温红外激发,pIRIR270℃)进行等效剂量测量,同时也应用post-IR OSL SAR法定年进行比较。实验结果表明,细粒混合矿物的pIRIR270℃等效剂量分别为418.8±13.2 Gy、562.3±18.2 Gy和694.8±17.9 Gy,相对应的post-IR OSL SAR等效剂量结果为345.0±29.4 Gy、409.6±33.7 Gy和424.7±32.2 Gy。假设强烈化学风化未对沉积物的剂量率造成很大影响,基于长石pIRIR270℃信号的释光年龄为89±6 ka、118±8 ka和152±9 ka,比前人所得的石英OSL SAR法年龄老30%~55%(约20~55 ka)。通过对比不同测量条件下获得的等效剂量值来评估长石IRSL信号是否存在晒退问题,没有发现长石post-IR IRSL信号存在晒退不完全的证据。根据本研究post-IR IRSL SAR法测年结果,赤山岛枫树嘴旧石器遗址似阿舍利技术类型的石器出现在倒数第二次冰期(MIS 6)后期至末次间冰期(MIS 5)前期,比湖南道县福岩洞现代人类牙齿化石年龄(80~120 ka)稍老。作为似阿舍利技术石器制造者的赤山岛古人与福岩洞现代人的关系将是我国旧石器时代考古学和古人类学研究的一个重要课题。     

商末气候变化对于稻作农业的影响——基于济南大辛庄、刘家庄遗址商代植物遗存观察

气候变化影响着农作物的生长。文章通过对比济南大辛庄遗址中、晚商时期的植物遗存和济南刘家庄遗址商末周初的植物遗存,发现两个遗址主要农作物均包括粟(Setaria italica (L.)Beauv.)、黍(Panicum miliaceum L.)、大豆(Glycine max(L.)Merr.)和小麦(Ttiticum aestivum L.),大辛庄遗址水稻(Oryza sativa L.)绝对数量较多,但刘家庄遗址未发现水稻。综合本地区其他遗址的植物考古研究结果,可以发现山东地区岳石文化时期、商代水稻仍是主要粮食作物之一,但到商末周初水稻数量急剧减少。同时,邻近的中原地区和关中地区,多处商周时期遗址水稻种植也普遍出现萎缩。多项地质记录表明,商末(3000 a B.P.前后)东亚夏季风快速减弱,降水量显著下降。山东地区受东亚季风影响,这一时期降水量减少,难以保证稻作农业所需的持续充足的水源,从而影响到水稻产量和种植规模。因此,商末气候变化很可能是刘家庄遗址商末周初水稻缺失以及山东地区商末周初水稻数量骤降的主要原因之一,也同时影响到整个黄河中下游这一时期的稻作农业。