The Plasma and Magnetic Field Characteristics of a Double Discontinuity in Interplanetary Space

A double discontinuity is a rarely observed compound structure composed of a slow shock layer and an adjoining rotational discontinuity layer in the downstream region. In this paper, we report the observations of a double discontinuity detected by Wind on May 15, 1997. This double discontinuity is found to be the front boundary of a magnetic cloud boundary layer. We strictly identify the shock layer and the rotational discontinuity layer by using the high-resolution plasma and magnetic field data from Wind. The observed jump conditions of the upstream and downstream region of the slow shock layer are in good agreement with the Rankine – Hugoniot relations. The flow speeds in the shock frame U _n <V _Acos θ _Bn on both sides of the slow shock layer. In the upstream region, the slow Mach number M _s1=U _n1/V _s1 is 1.95 (above unity), and in the downstream region, the slow Mach number M _s2=U _n2/V _s2 is 0.31 (below unity). Here V _A and V _s represent the Alfvén speed and the local slow magnetosonic speed, respectively, and θ _Bn is the angle between the direction of the magnetic field and the shock normal. The magnetic cloud boundary layer observed by Wind was also detected by Geotail 48 min later when the spacecraft was located outside the bow shock of the magnetosphere. However, Geotail observations showed that its front boundary was no longer a double discontinuity and the rotational discontinuity layer disappeared, indicating that this double discontinuity was unstable when propagating from Wind to Geotail.     

Test area of the SAGE survey

Sky surveys represent one of the most important efforts to improve developments in astrophysics,especially when using new photometric bands. We are performing the Stellar Abundance and Galactic Evolution(SAGE) survey with a self-designed SAGE photometric system, which is composed of eight photometric bands. The project mainly aims to study the stellar atmospheric parameters of ～0.5 billion stars in ～12 000 deg2 of the northern sky, which mainly focuses on Galactic astronomy, as well as some aspects of extragalactic astronomy. This work introduces the detailed data reduction process of the test field NGC 6791, including the data reduction of single-exposure images and stacked multi-exposure images, and properties of the final catalog.     

II型超新星瞬发爆炸模型的对流不稳定性

本文研究ＩＩ型超新星瞬发爆炸模型中的铁星核在坍缩、反弹和激波传播过程中的对流不稳定性．发现在铁星核内区出现中子指状对流,外区出现Ｓｃｈｗａｒｚｓｃｈｉｌｄ对流,而在声速点和中微子俘陷球之间的过渡区出现Ｌｅｄｏｕｘ对流．在０．７４－０．９１Ｍ间的区域是对流不稳定的活跃区域．     

Data processing and initial results from the CE-3 Extreme Ultraviolet Camera

The Extreme Ultraviolet Camera(EUVC) onboard the Chang'e-3(CE-3)lander is used to observe the structure and dynamics of Earth's plasmasphere from the Moon. By detecting the resonance line emission of helium ions(He+) at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius(RE) in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plasmasphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.     

A Research on the Gravity Deformation of Delingha 13.7m Telescope

Based on digital photogrammetric measurements, the antenna panels of the Delingha 13.7m radio telescope are adjusted to make the main dish have an optimal paraboloidal surface at the elevation of 52°, thus the overall antenna efficiency is optimized for different observing elevations. Observations indicate that the aperture efficiency of the telescope has been improved approximately twice in comparison with the antenna panels adjusted on the basis of theodolite measurements. According to the results of the measurements at different elevations, the models of antenna gravity deformation are built, including the displacement and tilt angle of the subreflector, as well as the focal length and surface error of the main reflector, as functions of elevation angle. In the process of modeling the gravity deformation of the main dish, instead of the direct calculation method, the least square fitting on the measured surface errors at different elevation angles is adopted, in order to reduce the effect of measurement errors on the accuracy of the model.     

Climate projections of spatial variations in coastal storm surges along the Gulf of Mexico and U.S. east coast

Using statistically downscaled atmospheric forcing, we performed a numerical investigation to evaluate future climate's impact on storm surges along the Gulf of Mexico and U.S. east coast. The focus is on the impact of climatic changes in wind pattern and surface pressure while neglecting sea level rise and other factors. We adapted the regional ocean model system(ROMS) to the study region with a mesh grid size of 7–10 km in horizontal and 18 vertical layers. The model was validated by a hindcast of the coastal sea levels in the winter of 2008. Model's robustness was confirmed by the good agreement between model-simulated and observed sea levels at 37 tidal gages. Two 10-year forecasts, one for the IPCC Pre-Industry(PI) and the other for the A1 FI scenario, were conducted. The differences in model-simulated surge heights under the two climate scenarios were analyzed. We identified three types of responses in extreme surge heights to future climate: a clear decrease in Middle Atlantic Bight, an increase in the western Gulf of Mexico, and non-significant response for the remaining area. Such spatial pattern is also consistent with previous projections of sea surface winds and ocean wave heights.     

压力分散型预应力锚索张拉试验及应力损失探讨

以某边坡工程压力分散型预预应力锚索的张拉试验为基础,介绍了压力分散型预应力锚索工作机理及张拉试验过程,并对应力损失、预应力筋的伸长量及桩身变形进行分析和初步探讨。     

THE CORRESPONDING ANALYSIS OF HEAVY-METAL POLLUTION OF SOIL IN ZHUZHOU CITY

ＴＨＥ ＣＯＲＲＥＳＰＯＮＤＩＮＧ ＡＮＡＬＹＳＩＳ ＯＦ ＨＥＡＶＹ－ＭＥＴＡＬ ＰＯＬＬＵＴＩＯＮ ＯＦ ＳＯＩＬ ＩＮ ＺＨＵＺＨＯＵ ＣＩＴＹ ＳｈａｎｇＪｉｎｃｈｅｎｇ（尚金城）；ＬｏｎｇＡｉｍｉｎ（龙爱民）ＬｉＢｉｎ（李斌）；ＪｉａｎｇＪ...     

X60钢在CO2饱和盐水中缓蚀作用的研究

本文采用动电位极化、线性极化、电偶电流和高压釜挂片失重等法,研究了含氮、硫有机缓蚀剂和/或Me~(2+)对X60钢在CO_2饱和的盐水溶液中的缓蚀作用。结果表明,含氮、硫的有机缓蚀剂在缓蚀过程中,开始是以抑制阳极过程为主,随后是以抑制阴极过程为主的混合型缓蚀剂。如与Me~(2+)复配使用,能明显地提高缓蚀效能。     

黄海近岸锋面的时空变化及其对沉积物输运和沉积的影响

利用2010和2012年黄海海域不同季节的航次观测数据与HYCOM模式再分析数据进行了比对,检验了HYCOM模式的水体温度数据在黄海海域的适用性。据此分析了黄海海域的温度锋面和混合锋面的时空变化。结果显示,温度锋通常在秋季开始出现,在冬季最为发育,在春季逐渐消失;黄海混合锋面与季风活动密切相关,主要在秋季开始出现,在冬季发育。悬浮沉积物基本上集中在温度锋的向岸一侧,难以跨越锋面输运。山东半岛成山头海域的温度锋在形态及空间位置上与泥质沉积区相对应,沉积中心(厚度40 m)主要分布在温度锋的西侧,而在其东侧泥质沉积厚度快速减小。研究结果发现,秋冬季节混合锋与温度锋的空间位置并不一致,混合锋位于温度锋的西侧,强烈混合使得沉积物不易沉降,对应泥质沉积厚度小;而在混合锋东侧,悬浮沉积物浓度高且水体层化显著,沉积物易于沉降堆积,与泥质沉积中心对应。混合锋与温度锋的空间分布差异与共同作用可能是该区域泥质沉积体"Ω"形态发育的动力学机制。