Bellhop模型在拖线阵声呐效能分析中的应用

针对拖线阵声呐反潜作战运用问题,分析了拖线阵声呐战术决策过程,提出了基于射线理论的主动拖线阵声呐搜索航线搜索效能统计模型。通过台湾以东海域主动拖线阵声呐声场仿真实例,分析了台湾以东海域海底地形对主动拖线阵声呐探测的影响,给出台湾以东海域主动拖线阵声呐反潜运用的相关建议。     

马兰黄土的应力-应变本构方程

依据马兰黄土的室内CU试验,运用土力学的相关理论,建议性地提出了马兰黄土的应力-应变本构方程。通过对不同围压下的试验结果(应变小于15%)与理论模型的拟合发现,二者吻合较好。另外,与以往的模型相比,本文的模型参数a和b只需通过一次常规三轴试验即可全部求得,具有参数少、容易确定的优点。     

地形变数字观测基础

介绍了将地形变模拟信号变换成数字信号过程中所作的采样、保持、量化与传输等环节，地采样过程的原理及其物理含义作了详细的阐述，并以对固体潮连续信号的采样为例作了说明。     

Thoughts and effects for substituted resource prospecting in Laozuoshan gold deposit in Heilongjiang

According to the Geological settings and the distributed laws of ore bodies and previous research results, combining with latest theories and new methods of geological prospecting, the authors proposed prospecting thoughts for substituted resources in Laozuoshan gold deposit. After ore prospecting in two years, nine new blind ore bodies were found, among which four ore bodies contain 4218.1 kg inferred intrinsic economic resources (333), and mitigate the crisis situation of mine reserves. At the same time, lots of significant geophysical and geochemical anomalies were found in the peripheral, which provide a basis for further prospecting.     

Fifty years of Quaternary palynology in the Tibetan Plateau

Science China Earth Sciences - Quaternary palynology in the Tibetan Plateau (TP) was initiated in the 1960s to meet the needs of economic development in western China. Pollen analysis was conducted...     

大气电场仪观测结果的修订

大气电场仪是测量大气电场的重要设备,其测量结果受多种因素影响.通过一系列对比试验表明:电场仪采用探头正置或倒置结构时的观测结果基本一致,倒置结构有利于避免雨水带来的影响.不同的安装环境对测量结果的影响很大,为了消除这种影响,提出了对观测数据进行地面修订的方法,得到不同天气条件下的修订系数.所得结果对于实现多站电场仪联网观测的数据一致性有重要实际意义.     

The benefits of recent warming for maize production in high latitude China

Latitudes above 45°N have been characterized by rates of warming faster than the global average since 1980. However, the effects of this warming on crop production at these latitudes are still unclear. Using 30-years of weather and crop management data in Heilongjiang area of China (43.4° to 53.4°N), combined with the Hybrid-Maize model, we show that that maize yields would have stagnated in most areas and decreased in the southern part of Heilongjiang if varieties were assumed fixed since 1980. However, we show that through farmers’ adaptation, warming has benefitted maize production for much of this region. Specifically, farmers gradually chose longer maturing varieties, resulting in a net 7–17 % yield increase per decade. Meanwhile, farmers also rapidly expanded maize area (from 1.88 million ha in 1980 to 4.01 million ha in 2009) and the northward limit of maize area shifted by more than 290 km from ~50.8°N to ~53.4°N. Overall, benefits from warming represented 35 % of the overall yield gains in the region over this period. The results indicate substantial ongoing adaptations and benefits at north high-latitudes, although they still represent a small fraction of global maize area. The sustainability of crop area expansion in these regions remains unclear and deserves further study.     

A novel framework for detecting non-recurrent road traffic anomalies by combining a temporal graph convolutional network and hierarchical time memory detector

A non-recurrent road traffic anomaly refers to a sudden change in the capacity of a road segment, which deviates from the general traffic patterns, and is usually caused by abnormal traffic events such as traffic accidents and unexpected road maintenance. Timely and accurate detection of non-recurrent road traffic anomalies facilitates immediate handling to reduce the wastage of resources and the risk of secondary accidents. Compared with other types of traffic anomaly detection methods, prediction algorithms are suitable for detecting non-recurrent anomalies for their potential ability to distinguish non-recurrent anomalies from recurrent congestion (e.g., rush hours). A typical prediction algorithm detects an anomaly when the difference between the predicted traffic parameter (i.e., speed) and the actual one is greater than a threshold. However, the subjective setting of thresholds in many prediction algorithms greatly affects the detection performance. This study proposes a novel framework for non-recurrent road traffic anomaly detection (NRRTAD). The temporal graph convolutional network (T-GCN) model acts as the predictor to learn the general traffic patterns of road segments by capturing both the topological effects and temporal patterns of traffic flows, and to predict the “normal” traffic speeds. The hierarchical time memory detector (HTM-detector) algorithm acts as the detector to evaluate the differences between the predicted speeds and the actual speeds to detect non-recurrent anomalies without setting a threshold. In the experiments with traffic datasets of Beijing, NRRTAD outperformed other methods, not only achieving the highest detection rates but also exhibiting higher resilience to noise. The main advantages of NRRTAD are as follows: (1) adopting the T-GCN with a weighted graph to integrate differentiated connection strengths of multiple types of topological relations between road segments as well as temporal traffic patterns improves the prediction performance; and (2) utilizing a flexible mechanism in the HTM-detector to adapt to changing stream data not only avoids subjective setting of a threshold, but also improves the accuracy and robustness of anomaly detection.     

Overburden deformation induced by active diapirism: Discrete element numerical simulations

Active diapirs are commonly observed in sedimentary basins worldwide. Factors controlling overburden deformation processes and patterns during the active rise of active diapirs, such as sediment cohesion and overburden thickness, are not well understood. We have utilised the discrete element numerical simulation method to simulate active diapirism in models comprised of sediments with varying cohesions and roof thicknesses. We found that sediment cohesion can significantly affect overburden deformation with low-cohesion sediments favouring the generation of a broad, smooth forced fold and a symmetric graben, while high-cohesion sediments favour the formation of master reverse faults and preferentially uplifted and rotated fault blocks in their hangingwalls in the central crest, with an overall asymmetric structural geometry. Moreover, overburden thickness does not significantly affect structural styles in the overburden. Our results also suggest that the higher the sediment cohesion, the higher the amplitude (the lower the wavelength) of the forced fold above the rising diapir becomes. Our models produced a wide spectrum of deformation structures that resemble those in nature and reveal a strong link between structural styles and sediment diagenesis in the context of active diapir-piercing sediments with varying degrees of lithification.     

面向应急观测规划的对地观测传感器集成管理方法与应用

随着对地观测技术的发展,地学传感器种类与数量日益增加,为了高效管理对地观测传感网中的传感器资源,以及分析对地观测应急事件的特点和传感器应急观测规划的需求,本文提出面向应急观测规划的对地观测传感器资源集成管理方法。其包括对地观测传感器信息资源组织与索引、天基传感器对地观测覆盖计算、面向应急协同观测的元数据查询设计。鉴此,本文以Java平台和传感网信息模型规范SensorML为基础,设计并实现了面向应急观测规划的对地观测传感器集成管理工具GeoSensorQuery。最后,以长江流域中游洪涝监测传感器规划为例,验证了本文方法的可行性。