Correlation analysis and causality test between Ludong-Huanghai block and South Japan

In this paper, we make a comparative analysis and correlation test for the seismic activities in the South Japan and the Ludong-Huanghai block (a secondary tectonic unit in the North China) and approach the relationship between the energy release processes of these two areas by using co-integration analysis and Granger causality test for the time series of random variables. The results show that the seismic activities in these two areas are correlative and synchronous to a certain extent, and their release series of cumulative strain energy are contemporaneously cor-relative. Both energy series are first-order difference stationary processes and there is secular and steady co-integration between them. We make a positive analysis on the first-order difference energy series through Granger causality test based on vector error correction (VEC) model and find there is unilateral Granger causality and prominent co-integration between the two energy release processes.     

澜沧江河道冲淤变化与来沙系数的格兰吉尔因果分析

采用格兰吉尔因果关系模型以及时间序列平稳性的ADF检验技术,结合23年的实测资料数据,分析了澜沧江天然来沙量的变化是否会导致澜沧江河道冲淤发生变化。结果发现:(1) 澜沧江历年来沙系数变化是一个不稳定的时间过程、但历年冲淤变化却是一个稳定的时间过程;(2) 澜沧江河道(允景洪断面)历年来沙系数变化对于冲淤变化不存在格兰吉尔因果关系,或前者对后者无预测关系,因此澜沧江河道来沙系数的增加(或减少)都不一定导致断面淤积量增大(或冲刷量增大)。前人得出的"随来沙系数的增大,断面淤积量有所增加,反之,则冲刷量增加"的结论值得商榷。     

吕宋冷涡的年际变化及影响机制分析

基于吕宋岛附近海域1985-2020年的海表温度、风应力和海面高度等卫星资料,分析吕宋冷涡(Luzon Cold Eddy,LCE)强度及中心位置的年际及长期变化趋势,探讨风场和黑潮入侵在LCE变化过程中的作用.结果 表明:35 a来,LCE整体呈现减弱趋势,其中心位置最大概率出现在(117°54′E,18°06′N)...     

Might electricity consumption cause urbanization instead? Evidence from heterogeneous panel long-run causality tests

The share of a population living in urban areas, or urbanization, is both an important demographic, socio-economic phenomenon and a popular explanatory variable in macro-level models of energy and electricity consumption and their resulting carbon emissions. Indeed, there is a substantial, growing subset of the global modeling literature that seeks to link urbanization with energy and electricity consumption, as well as with carbon emissions. This paper aims to inform both modelers and model consumers about the appropriateness of establishing such a link by examining the nature of long-run causality between electricity consumption and urbanization using heterogeneous panel methods and data from 105 countries spanning 1971–2009. In addition, the analysis of the time series properties of urbanization has implications both for modelers and for understanding the urbanization phenomenon. We consider total, industrial, and residential aggregations of electricity consumption per capita, three income-based panels, and three geography-based panels for non-OECD countries. The panel unit root, cointegration, and causality tests used account for cross-sectional dependence, nonstationarity, and heterogeneity – all of which are present in the data set. We cannot reject pervasively Granger causality in the urbanization to electricity consumption direction. However, the causality finding that is both the strongest and most similar across the various panels is that of long-run Granger causality from electricity consumption to urbanization. In other words, the employment and quality of life opportunities that access to electricity afford likely encourage migration to cities, and thus, cause urbanization. Also, nearly all countries’ urbanization series contained structural breaks, and the most recent post-break annual change rates suggested that nearly all countries’ rates of urbanization change were slowing. Lastly, future modeling work on energy consumption or carbon emissions should consider subnational scales of analysis, and focus on measures of urban density or urban form rather than national urbanization levels.     

汶川M_S8.0地震彭州灾区典型震害与成因初步分析

2008年5月12日14时28分汶川发生的8.0级大地震对我国四川省西部及西北部县市造成了特别严重,甚至是毁灭性破坏.基于现场调查资料,分析了彭州灾区的灾害空间分布,描述了典型建筑物破坏和大型滑坡体等地质灾害现象,并结合彭州地区房屋抗震设防情况,对此次地震灾害的主要成因进行了分析.结果表明,本次地震灾害的主要成因包括震级大、破坏力强,滑坡崩塌等地震地质灾害严重,农村建筑物缺乏必要的抗震设防措施等.在未来的规划与建设中,应避开断层、滑坡危险区域,并加强对农村地区建筑物的抗震设防指导.     

Transform methods for frequency‐dependent complex stiffness to time domain using real or imaginary data only

The author has studied the transform method of complex stiffness, which is strongly dependent on frequency, to the time domain. In this paper, new transform methods that use only the real part or the imaginary part data are proposed. By applying them to example problems, it is confirmed that the accuracy of the proposed methods is almost high in both causal and noncausal cases. These methods can also be thought as a standby for the Hilbert transform, because the undefined part is easily calculated by the recovering complex function from the obtained impulse response. Copyright © 2007 John Wiley & Sons, Ltd.     

北京气候变暖与主要极端气温指数的归因分析

在对资料进行均一化处理的基础上,分析了北京1960—2008 年气候变暖及主要极端气温指数的统计特征,并应用格兰杰检验法对其进行归因分析。结果表明:(1) 近49 a 来北京年平均气温增速约为0.39 ℃/(10 a),气候增暖具有明显的非对称性。(2) 霜冻指数和气温年较差呈下降趋势,降幅为3.9 d/(10 a)和0.8 ℃/(10 a)。生长季指数、暖夜指数及热浪指数则呈上升趋势,增幅平均达3.0 d/(10 a)、0.75%/(10 a)和1.5 d/(10 a)。(3) 北京年平均气温是霜冻指数、生长季指数及暖夜指数发生变化的格兰杰原因。虽然年平均气温与热浪指数在不同滞后期均具强相关性,但是检验表明它们之间并无显著的因果关系,很可能是由于某种原因导致的一种统计上的伪相关现象。      

我国留学生人数的预测及其对居民消费的影响

采用1985-2012年数据,利用时间序列分析方法,建立了刻画我国出国留学人数变动的模型ARIMA（2,2,2）,得到较好的预测效果.同时研究了出国留学人数与我国城镇居民人均消费性支出之间的关系,建立了相应的模型,并进行了Granger 因果关系检验.结果表明：出国留学生数的对数每增加1%,城镇居民人均消费性支出的对数将增加近0.06%.     

国内就业结构演变与旅游需求关系研究

通过就业结构演变驱动旅游需求的简单反馈模型假设,利用单位根检验(unit root test)、协整检验(cointegra-tion test)和格兰杰因果检验(Granger causality test)计量方法,以我国1984-2006年三大产业的就业人数和国内旅游人次变动数据为依据,探讨国内就业结构演变与旅游需求变化的关系。实证结果表明,三大产业就业结构演变与国内旅游人次的变化具有很强的相关性,其间存在长期稳定的均衡关系且具有正负增长递减的规律;第一产业就业人数的减少是国内旅游需求增长的重要驱动因素。     

THE N-FACTOR AS A TOOL IN GEOCRYOLOGICAL MAPPING: SEASONAL THAW IN THE KUPARUK RIVER BASIN,ALASKA

Although maps of active-layer thickness have useful roles in geocryology, polar ecology, and hydrology, a lack of geographically distributed data at appropriate scales has prevented their widespread implementation. The n-factor (ratio of temperature at the soil surface to that in the air) has considerable potential as a tool for mapping active-layer thickness and other geocryological parameters by providing refinements to relatively simple analytic solutions for the depth of thaw. Although temperature data from the soil surface under representative land-cover units have rarely been collected historically, recent advancements in data-logger technology allow the variability of soil-surface temperature regimes to be assessed inexpensively over small temporal and spatial intervals. Temperature data collected in the air at 2 m height and at the soil surface within 10 representative land-cover units in the Kuparuk River region of north-central Alaska were used to compute seasonal n-factor values for specific vegetation-soil associations. The resulting values were used with degree-day sums, a digital elevation model, and a digital map of vegetation to compute a modified Stefan estimate of thaw depth over a 26,278 km² area. Comparisons between maps based on the n-factor and an empirical, data-intensive method show similar performance. Given sufficient ancillary data, the n-factor provides a useful tool for mapping active-layer thickness over large areas without intensive in situ data collection. [Key words: Alaska, permafrost, active-layer thickness, frozen ground, mapping, temperature.]