A Model for Structure Formation Seeded by Gravitationally Produced Matter

The Arecibo H i Strip Survey probed the halos of approximately 300 cataloged galaxies and the environments of approximately 14 groups with sensitivity to neutral hydrogen masses >/=107 M middle dot in circle. The survey detected no objects with properties resembling the high-velocity clouds (HVCs) associated with the Milky Way or Local Group. If the HVCs were typically MHi=107.5 M middle dot in circle objects distributed throughout groups and galaxy halos at distances of approximately 1 Mpc, the survey should have made approximately 70 HVC detections in groups and approximately 250 detections around galaxies. The null detection implies that HVCs are deployed at typical distances of 相似文献   

低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和处理方法。为了进一步完善采用组合固定角距法测定对径改正的方法，在第三章，研究了提高对径改正测量精度的方法，重新推导了对径改正的计算公式，并就某些具体的条件，对其进行了模拟验证，得到了较为满意的结果     

An Emulation Research on the Radio Occultation Exploration of Martian Ionosphere

The technical system of the Sino-Russian joint satellite-to-satellite Mars ionosphere occultation is analyzed and introduced. The analogue computation of the observed values of the radio waves of the ionosphere occultation event is carried out by adopting the three-dimensional ray tracking method and the electron density profile inversion is conducted by means of the simulated occultation observational data, with the result showing that the emulation algorithm is reliable. By taking advantage of the emulation method the case computation and analysis of the inversion errors caused by the observational error of the occultation radio wave phase and the satellite orbital error are respectively carried out, and it is obtained from the result that the effect of the phase measuring error of the 5% circle on the result of the daytime ionosphere occultation exploration may be neglected, while the absolute error of the night electron density measurement is less than 4 × 108 m^?3, and the main effect of the satellite orbital error on the occultation leads to the lifting or falling of the ionospheric height. The result shows that the technical system of the Sino-Russian joint Mars ionosphere occultation exploration is advanced. It can be expected that the high accuracy electron density profile is obtained and the technical system can be applied to the exploration of the lunar ionospheric environment.     

回声测深仪在水下地形测量中的应用

本文在介绍回声测深仪基本工作原理的同时,介绍了回声测深仪在杭州湾口外一拟建大型码头下地形测量的一个应用实例。     

Capsizing Probability of Dead Ship Stability in Beam Wind and Wave for Damaged Ship

The International Maritime Organization has developed the second-generation intact stability criteria. Thus, damage stability criteria can be established in the future. In order to identity the capsizing probability of damaged ship under dead ship condition, this paper investigates two methods that can be used to research the capsizing probability in time domain, which mainly focus on the nonlinear righting lever GZ curve solution. One method subjects the influence of damaged tanks on the hull shape down to the wind and wave, and the other method is consistent with the real-time calculation of the GZ curve. On the basis of one degree of freedom rolling equation, the solution is Monte Carlo method, and a damaged fishery bureau vessel is taken as a sample ship. In addition, the results of the time-domain capsizing probability under different loading conditions are compared and analyzed. The relation of GM and heeling angle with the capsizing probability is investigated, and its possible reason is analyzed. On the basis of combining the time-domain flooding process with the capsizing probability calculation, this research aims to lay the foundation for the study of capsizing probability in time domain under dead ship condition, as well as provide technical support for capsizing mechanism of dead ship stability and damage stability criteria establishment in waves.     

Role of buffer layer in electronic structures of iron phthalocyanine molecules on Au(111)

We investigate the electronic structures of one and two monolayer iron phthalocyanine (FePc) molecules on Au(111) surfaces. The first monolayer FePc is lying flat on the Au(111) substrate, and the second monolayer FePc is tilted at ～15° relative to the substrate plane along the nearest neighbour [101^-] direction with a lobe downward to the central hole of the unit cell in the first layer. The structural information obtained by first-principles calculations is in agreement with the experiment results. Furthermore, it is demonstrated that the electronic structures of FePc molecules in one-monolayer FePc/Au(111) system are perturbed significantly, while the electronic structures of FePc molecules in the second monolayer in two-monolayer FePc/Au(111) system remain almost unchanged due to the screening of the buffer layer on Au(111).     

建制式反水雷装备发展特点分析及建议

水雷由于隐蔽性好、威力巨大、效费比高等优点,被许多国家作为重要的一种水种兵器。随着我国海军战略由近海防御向近海防御与中远海护卫转变,反水雷作战范围将延伸到第一岛链以外的海域,针对中远海的反水雷需求,我国应加紧研制建制式反水雷装备,提升编队的反水雷能力。     

δ18O and δ13C in fossil shells of Radix sp. from the sediment succession of a dammed palaeo‐lake in the Yarlung Tsangpo valley,Tibet, China

A series of confirmed and suspected dammed palaeo‐lake sedimentary successions is scattered within the middle Yarlung Tsangpo valley in Tibet. However, the chronology, the genesis of the dam and its location, the water level of the dammed lake, the process of dam failure and the spatiotemporal relationships between the sedimentary successions remain controversial. Here, we focus on one sedimentary succession of the suspected dammed palaeo‐lake at Xigazê. We measured the grain‐size distribution, magnetic susceptibility, organic and inorganic carbon content, and δ¹³C_org and δ¹⁵N_total ratios of the sediments. In addition, we measured the δ¹⁸O_shell and δ¹³C_shell values of modern and fossil Radix sp. shells, and the δ¹⁸O_water and δ¹³C_DIC values of the ambient water with different hydrological regimes. The results indicate that the δ¹⁸O_shell values of modern Radix sp. and the δ¹⁸O_water of the ambient water body significantly depend on its hydrological status. In addition, a strong positive relationship was observed between δ¹⁸O_shell values of modern Radix sp. shells and the δ¹⁸O_water of the ambient water on the Tibetan Plateau. According to this correlation, the δ¹⁸O_water values of the palaeo‐water body are reconstructed using the δ¹⁸O_shell values of Radix sp. fossil shells in the Xigazê section. Further, based on the δ¹⁸O_shell values of fossil Radix sp., the reconstructed δ¹⁸O_water of the palaeo‐water body and the specific habitats of Radix sp., we infer that the sedimentary succession in the Xigazê broad valley was mainly formed within the backwater terminal zone of a dammed palaeo‐lake and that the elevation of the water level of the lake was approximately 3811 m a.s.l. AMS ¹⁴C dating indicates that the deposits of the dammed palaeo‐lake were formed at about 33–22 cal. ka BP. Finally, the presence of Radix sp. fossil shells within the Xigazê section suggests that Radix sp. survived the late Last Glacial Period on the Tibetan Plateau.     

30ka以来南海东北部陆坡坡底沉积有机质的长链正构烷烃特征及其古植被意义

为探寻南海深海平原区的有机质组成特征、来源及其所反映的古气候/环境演化信息, 对南海东北部深水区的ZSQD289沉积柱状样品进行了正构烷烃组成及其单体稳定碳同位素的相关分析, 结合孢粉鉴定结果, 重点探讨该沉积区末次冰期以来陆源输入变化、源区的古植被演化及其气候响应因素。结果表明:30ka以来, 南海东北部深海陆坡坡底的沉积有机质以洋/陆混源为特征, 且以海洋自生生产力贡献为主, 其生源贡献存在明显的冰期/间冰期旋回变化特征, 冰期时陆源有机质输入明显高于全新世间冰期; 其陆源有机质应该主要由台湾南部河流输入, 在低海平面时通过海底峡谷搬运至此, 其过程中可能受到西太平洋底流和黑潮的影响。该沉积源区植被演化经历了C3/C4植物互为消长的变化过程, 但30ka以来主要还是以C3植物占优势, 由此推测末次冰期以来源区(台湾岛南部)不存在明显的干旱化, 冰期虽然温度较低但气候比较湿润。     

Fluid unmixing/immiscibility as an ore-forming process in the giant REE–Nb–Fe deposit, Inner Mongolian, China: Evidence from fluid inclusions

The giant Bayan Obo REE–Nb–Fe deposit consists of replacement bodies hosted in dolomite marble made up of magnetite, REE fluorocarbonates, fluorite, aegirine, amphibole, calcite and barite. Two or three phase CO₂-rich, three phase hypersaline liquid–vapor–solid, and two phase liquid-rich inclusions have been recognized in mineralized fluorite and quartz samples. Microthermometry measurements indicate that the carbonic phase in CO₂-rich inclusions is nearly pure CO₂. Fluids involving in REE–Nb–Fe mineralization at Bayan Obo might be mainly of H₂O–CO₂–NaCl–(F–REE) system. Coexistences of brine inclusions and CO₂-rich inclusions with similar homogenization temperatures give evidence that immiscibility happened during REE mineralization. An unmixing of an original H₂O–CO₂–NaCl fluid probably derived from carbonatitic magma. The presence of REE-carbonates as an abundant solid in fluid inclusions shows that the original ore-forming fluids are very rich in REE, and therefore, have the potential to produce economic REE ores at Bayan Obo.