NASA固体地球科学未来25年研究设想

在过去几十年,地球科学作为一门学科已经认识到,要把地球作为一个系统的动态的和相互联系的星球来研究。地球系统的每个组成部分之间以十分复杂的方式相互作用,来自每个组成部分的力量持续地驱动其它组成部分的响应。响应固体地球、大气圈、海洋、水圈、生物圈之间的复杂相互作用,以及地球内部的过程,地球表面一直处于变化之中———地震、火山喷发、破坏性洪水、滑坡和其它自然灾害,认识地球表面的这些变化是一个重大的科学挑战。固体地球科学的根本目标是评估和减轻严重危害人类健康和安全、国家安全、经济发展的自然灾害。为了迎接这…     

Tectonic wedging along the rear of the offshore Taiwan accretionary prism

The structural geometry, kinematics and density structure along the rear of the offshore Taiwan accretionary prism were studied using seismic reflection profiling and gravity modeling. Deformation between the offshore prism and forearc basin at the point of incipient collision, and southward into the region of subduction, has been interpreted as a tectonic wedge, similar to those observed along the front of mountain ranges. This tectonic wedge is bounded by an east-dipping roof thrust and a blind, west-dipping floor thrust. An east-dipping sequence of forearc-basin strata in the hanging wall of the roof thrust reaches a thickness in excess of 4 km near the tip of the interpreted tectonic wedge. Section restoration of the roof sequence yields an estimate of 4 km of shortening, which is small compared with that inferred in the collision area to the north, based on the variation in distance between the apex of the prism and the island arc.Previous studies propose that either high-angle normal faulting or backfolding has exhumed the metamorphic rocks along the eastern flank of the Central Range in the collision zone on land. To better constrain the initial crustal configuration, we tested 350 crustal models to fit the free-air gravity anomaly data in the offshore region to study the density structure along the rear of the accretionary prism in the subduction and initial collision zones before the structures become more complex in the collision zone on land. The gravity anomaly, observed in the region of subduction (20.2°N), can be modeled with the arc basement forming a trenchward-dipping backstop that is overlain by materials with densities in the range of sedimentary rocks. Near the point of incipient collision (20.9°N), however, the free-air gravity anomaly over the rear of the prism is approximately 40 mgal higher, compared with the region of subduction, and requires a significant component of high density crustal rocks within the tectonic wedge. These results suggest that the forearc basement may be deformed along the rear of the prism, associated with the onset of collision, but not in the subduction region further to the south.     

略论位(重力)基数测量在水利建设中的应用

为改变西部干旱缺水,在西部大开发中,大规模、长尺度地兴修水利,如南水北调,将有必要进行。基于同一个水准面上高程相同的原则,本文强调在上述工程的设计施工时应该使用与位基数意义相同的力高高程。据计算,在纬度差为12°,高差相差的近2500m的同一条测线上,现行的高程与力高高程相差7m之多,这样大的偏差是不能忽略的。文中对高程测量中重力点的布设及重力内插的精度等也提出了新的看法。     

湍流频散对边界层风廓线的影响

应用包括湍流粘性和频散的新的Reynolds平均动量方程，分析了边界层的垂直风速廓线，发现包含湍流频散的地面层的风速廓线对经典的风廓线指数规律有一个对数规律的修改；而且在不稳定层结下比在稳定层结下，湍流的频散效应更为显；在中性条件下，指数规律退化为对数规律并且Karman常数被另外一个常数所代替，而这个新常数也可以通过相似理论来获得。     

天时、与中国历史（Ⅱ）：“好（坏）天时”与历史上的“顺（乱）世”

中国历史上的“顺世”绝大多数（≈83％）出现在“好天时纪”中；绝大多数“乱世”出现在“坏天时纪”内（≈85％）。历史上的分裂期都出现在“长坏天时纪”中。依据“天时好、坏”与“顺世、乱世”的两两对应关系，可将历史上的皇帝分为贤、明、庸、暴四类。本世纪初开始的“长好天时纪”可能是中华民族又一个辉煌时期的开始。但是对“坏天时代”的可能干扰，应引起足够重视。     

运用S方法预测中等地震及小震震群活动性的研究

运用S方法处理流动地磁测量资料，与小震震群地震活动频次对比分析，结果表明流磁测线S值出现异常，一年内小震震群地震活动频次增高；反之，S值较小，则地震活动频次较低；流磁测线S值出现异常，其邻近地区可能发生MS4级左右地震。此方法在少震地区地震的中短期预测中有一定的实用意义。     

一种特殊土钉墙的设计与施工实践

论述了特殊土钉墙的设计思路和结构特征,介绍它的施工工序、工艺,总结了其支护效果、施工注意事项和推广应用价值。较好地解决了狭窄边界条件下基坑支护的难题。     

Exopolysaccharides from marine bacteria

Microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. In recent years, there has been a growing interest in isolating new exopolysaccharides (EPSs)-producing bacteria from marine environments, particularly from various extreme marine environments. Many new marine microbial EPSs with novel chemical compositions, properties and structures have been found to have potential applications in fields such as adhesives, textiles, pharmaceuticals and medicine for anti-cancer, food additives, oil recovery and metal removal in mining and industrial waste treatments, etc. This paper gives a brief summary of the information about the EPSs produced by marine bacteria, including their chemical compositions, properties and structures, together with their potential applications in industry.     

卫星视频舰船目标检测方法

舰船目标检测是进行海上目标监管,保障海上权益的重要手段.本文在SSD(single shot multibox detector)算法的基础上,利用残差网络(ResNet,residual network)作为骨干网络构建SSD模型,将改进后的SSD算法应用于卫星视频舰船目标检测,该算法采用残差连接替换原本的级联方式,...     

Effects of dissolved oxygen on intestinal bacterial community and immunity of Atlantic salmon Salmo salar

Journal of Oceanology and Limnology - Dissolved oxygen (DO) is one of most important factors which affect wide range physiologic features of fish, including immune responses and intestinal...