Solar sail time-optimal interplanetary transfer trajectory design

The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable. A solar sail is a method of propulsion that does not consume fuel. Transfer time is one of the most pressing problems of solar sail transfer trajectory design. This paper investigates the time-optimal interplanetary transfer trajectories to a circular orbit of given inclination and radius. The optimal control law is derived from the principle of maximization. An indirect method is used...     

基于二维模式的PDM与MRPⅡ无缝衔接可行性分析

ＣＩＭＳ工程的重要思想是将企业全部生产经营活动视为有机整体,可以集成与优化。但是,目前我国ＣＩＭＳ工程中ＰＤＭ与ＭＲＰⅡ分系统并未真正实现紧密结合与集成,甚至是彼此分离,无直接衔接。在实践经验的基础上,作者探讨了基于二维模式的ＰＤＭ与ＭＲＰⅡ紧密衔接可行性,提出了实现这一衔接的初步设想     

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).     

大陆岛入海沉积物通量的估算研究

大陆岛入海沉积物通量（Q_s）信息对于精确解译大陆架沉积记录的研究是个重要补充。针对如何估算大陆岛Q_s的科学问题,本文以中国东南部海域的8 227个大陆岛为例,提出了一种基于邻近大陆中小型河流Q_s的经验公式计算大陆岛Q_s的解决方案。该方案在实施时需设置两个假定,即大陆岛的Q_s法则遵循邻近大陆中小河流的Q_s法则和可将1个大陆岛当作1个河流流域计算其Q_s。结果表明：（1）经验公式计算的大陆岛Q_s为其最小估计值;如考虑大陆岛流域的具体情况,实际的Q_s值会稍微增加,但其增幅不超过n^0.13（n为流域数量）;（2）经验公式能获取大陆岛Q_s的大致数量级信息;大陆岛的总面积为4 418.49 km²,对应Q_s的数量级为10⁶ t/a,与邻近大陆中型河流入海通量的数量级相当;（3）在大河河口湾充填阶段完成以前,大陆岛沉积物是内陆架泥质沉积体的主要物源之一。因此,大陆岛入海沉积物会对大陆架沉积体系的形成和演化造成一定程度的影响,需引起研究人员的高度重视。     

中国地质学会第七届“黄汲清青年地质科学技术奖”评选揭晓

<正>2015年3月1日,中国地质学会"第七届黄汲清青年地质科学技术奖"终评会议在京召开,20位黄汲清青年地质科学技术奖基金管理委员会委员及代表出席会议,孟宪来常务副理事长主持会议。经无记名投票,产生了第七届黄汲清青年地质科学技术奖获奖者。根据《黄汲清青年地质科学技术奖奖励条例》,第七届黄汲清青年地质科学技术奖获奖者是经过单位推荐、资格审查、专家初评、公示及委员会终评等严格的评选程序,最终15     

南黄海盆地二叠系烃源岩孢粉相特征及其形成环境

以沉积环境控制烃源岩发育理论为指导,应用孢粉相分析方法,以南黄海盆地二叠系大隆组、龙潭组和栖霞组烃源岩层段为研究对象,对典型钻井剖面的孢粉及沉积有机屑进行系统的分析。根据沉积有机屑的丰度特征和组分类型,探讨三套烃源岩的形成环境,初步评价其生烃潜力。研究结果表明,利用孢粉相分析方法,可以有效地对高成熟海相烃源岩的生烃潜力和形成环境进行客观评价:栖霞组为缺氧远陆架沉积环境,以无定形有机质为主,水体分层缺氧,是烃源岩形成的有利环境;大隆组为缺氧和少氧的陆架环境,也较有利于烃源岩的形成,生烃潜力较栖霞组差;龙潭组煤质型有机质较为丰富,为充氧的陆架区,以陆源输入为主,沉积区水体较浅,含氧量高,不利于富氢烃源岩的形成。     

Application of low-pressure gas adsorption to nanopore structure characterisation of organic-rich lower Cambrian shale in the Upper Yangtze Platform,South China

The pores in shales are mainly on a nanometer scale, and the pore-size distribution is vital with regard to the preservation and exploitation of shale gas. This study focuses on the organic-rich lower Cambrian black shale in the Upper Yangtze Platform, South China and investigates their TOC, mineralogical composition and nanopore structure. Low-pressure N₂ and CO₂ adsorption experiments were conducted at 77.35 K and 273.15 K, respectively, and the nanopore structures were characterised by the modified Brunauer–Emmett–Teller, Dubinin–Radushkevich, t-plot, Barrett–Joyner–Halenda and density functional theory (DFT) methods. The results indicate the following. (1) The lower Cambrian shale has a high TOC content (1.77–7.23 wt%) and a high quartz content (27.7–51.6 vol%). The total specific surface area varies from 12.02 to 28.87 m²/g. Both the total specific surface area and quartz content are positively associated with the TOC content. (2) Shale samples with a higher TOC content have a greater number of micropores, resulting in more complicated nanopore structures. Micropore volumes/surface areas and non-micropore surface areas all increase with increasing TOC content, indicating that TOC is the key factor determining the nanopore structure of the lower Cambrian shale. (3) A combination of N₂ and CO₂ adsorption provides the most suitable detection range (～0.3–60 nm) and is both highly reliable and accurate with regard to nanopore structure characterisation.     

The diagenetic geochemistry and contamination assessment of iron,cadmium, and lead in the sediments from the Shuangtaizi estuary,China

Sediment and pore water samples have been collected from the coastal tidal flat in the Shuangtaizi estuary, China, in order to investigate the geochemical behavior of iron, cadmium, and lead during diagenesis and to assess the degree of contamination. The calculated enrichment factors and geoaccumulation indices for separate elements show that anthropogenic activities have had no significant influence on the distribution of Fe and Pb in the study area, whereas the distribution of Cd has been closely influenced in this way. The high percentage of exchangeable Cd (average of 56.34%) suggests that Cd represents a potential hazard to benthic organisms in the estuary. The calculated diffusive fluxes of metals show that the most mobilized metal is Fe (9.22 mg m^?2 a^?1), followed by Cd (0.54 mg m^?2 a^?1) and Pb (0.42 mg m^?2 a^?1). Low Fe²⁺ contents in surface pore water, alongside high chromium-reducible sulfur contents, and low acid-volatile sulfur, and elemental sulfur contents at 0–25 cm depth in sediments show that Fe²⁺ is formed by the reduction of Fe oxides and is transformed first to a solid phase of iron monosulfides (FeS) and eventually to pyrite (FeS₂). The release of adsorbed Pb due to reductive dissolution of Fe/Mn oxides during early diagenesis could be a source of Pb²⁺ in pore water. From the relatively low total organic carbon contents measured in sediments (0.46–1.28%, with an average of 0.94%) and the vertical variation of Cd²⁺ in pore water, sulfide or Fe/Mn oxides (instead of organic matter) are presumed to exert a significant influence on carrying or releasing Cd by the sediments.     

渤海湾北岸TZ02孔晚新生代沉积环境演化过程

渤海湾北岸晚新生代沉积环境和沉积体系不仅是区域水文地质、工程地质的基础,也为古近纪沉积模式提供“将今论古”的依据。本文依据沉积物色度和粒度,以及沉积物岩性、结构和构造等,将渤海湾北岸TZ02孔划分了6个沉积组合、4个沉积阶段：1）2.10~3.22Ma,沉积组合Ⅰ和Ⅱ,湖盆填充期,发育湖相-泛滥平原相或湖相-曲流河相,该时期处于构造稳定期,干冷气候时期发育河流相、泛滥平原相,湿润气候时期发育湖泊相。2）1.33~2.10Ma,沉积组合Ⅲ,湖盆开始发育期,主要为浅湖相,仅有少量砂体,下部多有机质,上部多钙质淀积结核,指示了盆山之间的构造分异后,湖泊初始发育的特征。3）0.62~1.33Ma,沉积组合Ⅳ,湖盆扩张期,以湖相为主,多砂体,且有短期湖泊水位变浅和成陆过程;指示了盆山构造分异后,盆地加速沉降,湖盆扩张;山体隆起、河流下切,盆地中湖相砂体增多;此时TZ02孔附近为湖相中心,BG10孔为湖泊边缘。4）0~0.62Ma,沉积组合Ⅴ和Ⅵ,湖泊填充期,BG10孔为湖相的沉积中心,而TZ02孔为湖泊的边缘,接受滦河迁移摆动后的沉积物;中更新世后,构造沉降形成湖相,而间冰期发育海相,埋深0~22.5m的海相-河流相更直接地反映了末次冰消期海平面变化过程。

     

中国优质环保型炼焦煤的评价及资源量等级

我国炼焦煤资源丰富，但优质炼焦煤一直处于短缺局面。根据全国已有煤质数据分析，从优质（主要考虑挥发分指标）、环保（主要考虑硫分和灰分指标）两个方面结合有害微量元素含量，将炼焦煤划分为四种类型，确定了优质环保型炼焦煤资源的评价步骤，对全国五个赋煤区优质环保型炼焦煤的资源量等级进行了统计分析。