基于以太网的水下自主航行器分布式控制系统研究

针对模块化小型 AUV 平台高速、宽带的数据通信需求和设备分散的特点,设计了一种分布式控制系统。 控制系统硬件采用基于网络的分布式架构,在较好地减少传输信号线,提高抗干扰能力的同时提高 AUV 平台的设备间兼容性和通信速率。 控制系统软件采用分层控制体系,由显控设备控制的任务层,控制计算机控制的自主层以及由微控制器节点控制的执行层,实现实时任务和控制命令的分离,减小任务层的运算量,方便软件的维护升级。 实航试验中 AUV 准确地完成了复杂的路径规划和地形测量任务,表明控制系统运行稳定可靠,为 AUV 平台的通用化、小型化设计提供参考。     

Searching for GeV gamma-ray emission from the bulge of M31

The three major large-scale, diffuse γ-ray structures of the Milky Way are the Galactic disk,a bulge-like GeV excess towards the Galactic center, and the Fermi bubble. Whether such structures can also be present in other normal galaxies remains an open question. M31, as the nearest massive normal galaxy, holds promise for spatially-resolving the γ-ray emission. Based on more than 8 years of Fermi-LAT observations, we use(1) disk,(2) bulge, and(3) disk-plus-bulge templates to model the spatial distribution of the γ-ray emission from M31. Among these, the disk-plus-bulge template delivers the best-fit, in which the bulge component has a TS value 25.7 and a photon-index of 2.57 ± 0.17, providing strong evidence for a centrally-concentrated γ-ray emission from M31, that is analogous to the Galactic center excess. The total0.2–300 GeV γ-ray luminosity from this bulge component is(1.16 ± 0.14) × 1038 erg s-1, which would require ～ 1.5 × 105 millisecond pulsars, if they were the dominant source. We also search for a Fermi bubble-like structure in M31 using the full dataset(pass8), but no significant evidence has been found.In addition, a likelihood analysis using only photons with the most accurate reconstructed direction(i.e.,PSF3-only data) reveals a 4.8 σ point-like source located at ～10 kpc to the northwest of the M31 disk, with a luminosity of(0.97 ± 0.27) × 1038 erg s-1 and a pho@ton-$i·nd3 ex of 2.31 ± 0.18. Lacking a counterpart on the southeast side of the disk, the relation between this point-like source and a bubble-like structure remains elusive.     

Effect of dry density on the liquefaction behaviour of Quaternary silt

Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt (dry density ρ_d=1.460 g/cm³) and dense silt (ρ_d=1.586 g/cm³) under different cyclic stress ratios (CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure (EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the “fast-stable” and “fast-gentle-sharp” growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.     

Dynamic behaviour of weathered red mudstone in Sichuan (China) under triaxial cyclic loading

The construction of a high-speed railway (HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. The ability to use weathered red mudstone (WRM) to fill subgrade beds by controlling its critical stress and cumulative strain would enable substantial savings in project investments and mitigate damage to the ecological environment. To better understand the dynamic behaviour of WRM, both monotonic and cyclic triaxial tests were performed. The evolution of the cumulative strain vs. increased loading cycles was measured. The influences of confining pressure and loading cycles on the dynamic modulus, damping ratio, critical cyclic stress ratio (CSR), and dynamic stress level (DSL) were investigated. The relationship between the CSR and loading cycles under different failure strain criteria (0.1%-1.0%) was analysed. The prediction model of cumulative strain was also evaluated. The results indicated that the shear strength of WRM sufficiently meets the static strength requirements of subgrade. The critical dynamic stress of WRM can thus satisfy the dynamic stress-bearing requirement of the HSR subgrade. The critical CSR decreases and displays a power function with increasing confining pressure. As the confining pressure increases, the DSL remains relatively stable, ranging between 0.153 and 0.163. Furthermore, the relationship between the dynamic strength and loading cycles required to cause failure was established. Finally, a newly developed model for determining cumulative strain was established. A prediction exercise showed that the model is in good agreement with the experimental data.     

“基本自然资源区”制度研究

为深化生态文明体制改革,建立健全自然资源统筹管理制度,为国土空间规划和用途管控提供新思路,文章分析和归纳相关研究背景和现有制度基础,从基本自然资源的主要特征、"基本自然资源区"的概念、分类分区和制度设计4个方面深入研究"基本自然资源区"制度。研究结果表明:在党和政府高度重视自然资源开发利用和保护以及自然资源部成立的背景下,我国实施基本自然资源统筹管理制度具有重要性和必要性,现有的农田和草原等自然资源管理和保护制度为其奠定基础;基本自然资源具有稀缺性、基础性、资产性和兼容性,"基本自然资源区"是科学规划的兼具资源生产功能和自然生态价值的国土空间,属于特殊的经营性资产,主要包括基本农田资源区、基本草原资源区、基本森林资源区、基本水资源区和基本滩涂资源区,未来可逐步吸纳其他自然资源;应从明确功能和管理定位、融入国土空间规划体系、严守管控底线、注重制度衔接和统筹以及搭建信息平台5个方面开展制度设计,探索构建以严格管控基本自然资源数量、质量和功能为主的基本自然资源统筹管理制度。     

辽河口沉积物中古菌和细菌群落结构分析

本研究旨在了解辽河口表层沉积物中古菌和细菌的群落结构组成、多样性及其与环境因子之间的相关性。采用构建古菌和细菌16S rRNA基因文库的方法,应用Illumina Miseq测序技术进行序列分析。结果表明:辽河口表层沉积物中细菌多样性高于古菌多样性,近岸细菌和古菌多样性高于远岸,即河相区（0.8~7.04）细菌多样性高于混合区（13.1~20.7）和海相区（24.2~31.5）;主要古菌群落为奇古菌门（Thaumarchaeota,72.73%）和广古菌门（Euryarchaeota,25.05%）,其中泉古菌门（Crenarchaeota,0.001%）只在河相区站位被发现;细菌群落组成中变形菌门（Proteobacteria,61.94%）为该河口的优势菌群,其次为拟杆菌门（Bacteroidetes,11.21%）和酸杆菌门（Acidobacteria,5.59%）,其他门类如蓝藻门（Cyanobacteria,3.03%）等比例较小。与环境因子的冗余度分析表明:影响表层沉积物中古菌群落分布的主要环境因子依次为氨盐、泥、酸碱度、盐度、电导率和砂,而细菌群落的分布主要受到溶氧、泥、砂、黏土和总磷的影响。由此可见,不同环境条件下微生物的群落结构存在空间异质性,不同微生物对同一环境条件的响应亦不同。     

尾流中悬浮拦截弹环境噪声特性研究

尾流自导鱼雷对水面舰艇构成严重威胁。 为了把悬浮拦截弹被动拦截方式从非尾流区域扩展到尾流区,拦截尾流自导鱼雷,需要研究尾流内噪声特点,分析出拦截弹在尾流区的环境噪声特性。 基于悬浮拦截弹对不同吨位舰船尾流噪声进行研究,结合高阶累积量从概率论的角度出发,计算了尾流噪声的斜度和峰度随尾流年龄的变化规律;噪声斜度判断噪声是否满足对称分布,峰度判断噪声是否为高斯信号。 将实测数据与仿真数据峰度和斜度进行比对,得出结论：舰船尾流噪声环境可以近似看作是高斯信号,服从对称分布,且该分布特性与舰船吨位不相关。     

秦巴山地山体基面高度的提取及分布

秦巴山地是中国的南北分界线,也是黄河和长江的分水岭,其山体效应的定量化影响秦巴山地山体垂直带的分布格局、非地带性因素的作用强度和机理,以及中国暖温带和北亚热带的具体位置的确定。山体基面高度是影响山体效应最重要和关键的地形因子,其定量化和数字化提取是秦巴山地山体效应定量化研究的重要内容。本研究针对秦巴山地山体效应的定量化研究,使用30 m分辨率的STRM-1数据,分别基于山体特征线和流域分区2种方法提取了秦巴山地的山体基面高度分区,并根据地形起伏度和坡度,确定基面范围,计算了山体基面高度值。结果表明：① 基于山体特征线的方法将秦巴山地分为93个基面高度分区,基于流域分区的方法将秦巴山地分为209个基面高度分区,根据2种分区结果提取的基面高度值相差不大且均体现了秦巴山地地势的特点;② 秦巴山地山体基面高度从东向西呈阶梯状递增的趋势;③ 从南到北,秦巴山地的东段和中段均呈先增高后降低的趋势,即从大巴山向北至汉江谷地降低,再向北至秦岭升高;④ 山地的不同侧翼的山体基面高度不同,秦岭南坡的基面高度（1000~1809 m）明显高于北坡（850~1300 m）。秦巴山地山体基面高度与其植被带分布上限联系密切,实现山体基面高度的数字化提取,为山体效应的定量化研究提供了重要的技术支持。     

大别山北部镁铁-超镁铁质岩带的研究新进展

报道了大别山北部镁铁－ 超镁铁质岩带研究的一些最新进展,其中特别重要的是两种产状新鲜榴辉岩露头的发现、超高压变质线索及变质蛇绿岩的地球化学证据等。讨论了该带需进一步研究的若干问题。     

西秦岭寒武系层控金矿床中成矿元素富集规律

产于西秦岭南亚带寒武系硅岩建造中的金矿床, 是我国境内发现的一种与海底喷流作用有关的、具有独特地质特征的层控金矿床。成矿元素富集规律研究表明, 矿床中富集的元素种类十分丰富, 不仅含有具基性、超基性特征的元素群, 而且含有具酸性特征的元素群, 元素组合相当复杂。除Ａｕ 外, Ｃｕ、Ｕ、Ｍｏ、Ｓｂ、Ｖ、Ｚｎ等在局部地段亦可圈出独立的矿体。尤为重要的是, 矿床中铂族元素（ＰＧＥ）、分散元素（Ｓｅ、Ｉｎ） 的富集程度达到了综合利用的程度, 从而构成特殊的Ａｕ－Ｃｕ－Ｕ－Ｍｏ－Ｓｅ－ＰＧＥ建造矿床。