东海黑潮PN和TK断面流量的多时间尺度变化特征

根据日本海洋数据中心提供的1972—2017年PN断面共181个航次和1987—2010年TK断面共92个航次的CTD调查资料,利用动力高度法估算了这2个断面的流量,分析了其季节、年际和长期变化特征。主要结果表明,PN断面流量季节变化为冬、春和夏季大而秋季小,TK断面流量季节变化为冬、夏季大而春、秋季小,二者共同点为最大(小)流量均出现在夏(秋)季。PN断面年平均流量的年际变化不明显,但冬季和夏季流量分别具有准3 a和准2 a的显著变化周期;TK断面年平均流量具有准4 a和准6 a的显著变化周期,冬季流量具有准4 a和准7 a的显著变化周期,但夏季流量无显著变化周期。此外,PN断面流量在1976年附近出现了一次较大幅度的增加。PN断面流量具有较大的长期增加趋势,增长率约为0.3 Sv/a,在1972—2017年增加了约13 Sv,结合NCEP海面风应力资料,结果显示,北太平洋更高纬度带(35°N和40°N)的风应力旋度对PN断面流量的影响更强。     

禹城市城乡用地结构和布局分析

统筹城乡用地、优化城乡用地结构和布局,既是节约和集约用地的重要途径,又是统筹城乡发展的客观需要.通过分析禹城市城乡用地结构和布局,提出优化城乡用地结构和布局的建议和对策,从而为制定合理的土地利用总体规划提供基本的依据.     

应用MATLAB设计高效多级抽取滤波器

介绍如何应用Matlab设计级联梳状(CIC)滤波器、半带滤波器和有限脉冲响应(FIR)滤波器。并设计了一种高效的多级抽取滤波器，将该算法用数字信号处理器(DSP)进行验证，结果表明，该多级抽取滤波器能满足地震数据采集系统的精度要求。     

台风"碧利斯"在厦门海域的酸沉降特征及其氮、磷营养盐对海洋的输入评估

通过对台风"碧利斯"影响期间厦门滨海地区降雨化学特征的研究,以及对台风降雨与春夏季降雨样品的比较研究发现:主要离子降雨的月沉降通量根据其特点可分为4类.台风降雨的pH明显大于非台风降雨,台风"碧利斯"和"格美"降雨样品的pH不具有酸雨特征.台风"碧利斯"的降雨能有效清除空气中的酸雨成分,同时减少对厦门滨海地区的酸沉降和对海洋的酸输入.春夏季降雨和台风降雨的N/P比都远高于海水Redfield值.通过估算发现台风"碧利斯"的直接湿沉降对台湾海峡西部表层海水DIN(溶解无机氮)有很大的增加,而PO43-的输入量则很小.     

Multielement analysis of deep-sea sediments by inductively coupled plasma mass spectrometry

Marine sediments were dissolved by HNO3-HF-HCIO4 in a sealed container at low pressure; I-IF was evaporated in an open container and salts were dissolved in HCl by heating, then transferred to 2% HNO3 solution. A total of 45 elements, including Li, Be, So, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, TI, Pb, Bi, Th and U, were measured by inductively coupled plasma mass spectrometry (ICP-MS). Condi-tions and sample experiments showed that this procedure defines a good experimental method which has the advantages of clear interference, easy operation and reliable results. The concentrations of the 45 elements could be used for resource exploration, envi-ronmental assessment and academic research.     

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。     

Dynamic transition mechanism analysis of the impact of energy development on urbanization in Central Asia

Journal of Geographical Sciences - Energy development has a significant impact on urbanization. This study employs the entropy method to evaluate the level of urbanization in Central Asia and...     

Runoff reconstruction for the Bailong River from tree rings back to AD 1601, reveals changing hydrological signals of China north–south transition zone

We present a runoff reconstruction for the Bailong River based on the composite chronology developed from four sampling sites of Pinus tabulaeformis in the China north–south transition zone. The runoff reconstruction, spanning 1601–2013 CE, was developed by calibrating tree-ring data with the instrumental runoff record. Runoff reconstruction accounted for 44.3% of the actual runoff variance during the common period 1958–2010 and provided a long-term perspective on hydrological change in the China north–south transition zone. In the past 413 years, high- and low-runoff years accounted for 15.50% and 15.98%, respectively. Of all the 17 extreme hydrological events, 14 of them are extremely high-flow years, and 17th century was the wettest period during the past 413 years. The preliminary analysis results show that there is a relationship between our runoff reconstruction and the Atlantic multidecadal oscillation at multidecadal scale. Since the 1990s, runoff in the China north–south transition zone has also seen a significant decrease as a result of dry trends of the source region.     

Simulating urban land use change by integrating a convolutional neural network with vector-based cellular automata

ABSTRACT

Vector-based cellular automata (VCA) models have been applied in land use change simulations at fine scales. However, the neighborhood effects of the driving factors are rarely considered in the exploration of the transition suitability of cells, leading to lower simulation accuracy. This study proposes a convolutional neural network (CNN)-VCA model that adopts the CNN to extract the high-level features of the driving factors within a neighborhood of an irregularly shaped cell and discover the relationships between multiple land use changes and driving factors at the neighborhood level. The proposed model was applied to simulate urban land use changes in Shenzhen, China. Compared with several VCA models using other machine learning methods, the proposed CNN-VCA model obtained the highest simulation accuracy (figure-of-merit = 0.361). The results indicated that the CNN-VCA model can effectively uncover the neighborhood effects of multiple driving factors on the developmental potential of land parcels and obtain more details on the morphological characteristics of land parcels. Moreover, the land use patterns of 2020 and 2025 under an ecological control strategy were simulated to provide decision support for urban planning.     

A High Thermal Conductivity Cement for Geothermal Exploitation Application

Natural Resources Research - In geothermal reservoir exploitation, the thermal conductivity of casing cement material is a key parameter that may affect the heat exchange and utilization efficiency...