基于人工蜂群优化的异尺度点云配准算法

针对不同尺度点云配准的精度和效率问题,提出一种基于人工蜂群优化的异尺度点云配准算法。引入尺度缩放因子,与三维旋转、平移参数共同作为配准过程中的待求变量,使用人工蜂群优化方法进行优化求解。同时,基于归一化尺度参数改进了欧氏距离目标函数,以消除优化求解中尺度缩放因子引起的误差,从而有效提高配准算法的稳定性。与当前几组典型方法进行对比,所提算法对不同模型配准的精度和效率均有提高。实验结果表明,所提算法充分利用了人工蜂群优化方法优异的全局优化能力,可以有效实现对异尺度点云的高精度、快速配准。

经济集聚机理的尺度分异整合及其应用价值研究

经济活动空间集聚是有尺度之分的。文章从企业—厂商、产业—行业和区域—地带三个尺度研究了经济活动空间集聚,认为在企业—厂商尺度上,空间集聚特点是企业增长和空间扩张,作用机理是内部规模经济和内部范围经济;在产业—行业尺度上,空间集聚特点是企业的空间邻近性,作用机理是外部规模经济和外部范围经济;在区域—地带尺度上,空间集聚特点是产业的区域复合,作用机理是区域外部规模经济。在此基础上,文章论述了经济活动空间集聚的不同尺度作用机理的内在统一性及其理论的实践价值。

苔原植物种群和植被的大尺度分异和动态

瑞典-俄罗斯94’苔原生态考察中所包含的植物学计划提供了关于苔原植物生态学的新信息,记载了不同尺度的植被格局,这是由于与环境因子间复杂相互作用的结果。考察中研究了木质地衣的分布,结果表明这些地衣依靠不同的无性繁殖模式进行扩散。苔草属物种表现出极大的基株年龄,与地衣有极相似的特征。尽管龄级较高且开花通常较少,但苔草具有较高的遗传多样性。在不同实验点间苔草开花和无性系分株生产有巨大的差异,反映了种群年际间的非同步波动,这与周期性的旅鼠种群和气候有关。这项研究提出了苔原植物生态学知识的重要空白点,其中一些可望在1999年西北苔原考察时得到解决。

多个部分与整体间异速生长关系的联合分析模型

简单的异速生长模型的反函数还是一个幂函数,也可以用于确定有机体的异速生长尺度关系;但此时得到的尺度指数(即异速生长指数)的含义,与由简单异速生长函数得到的尺度指数具有相反的生物学含义。基于以上考虑,建立了一个整体与多个体成分的联合静态异速生长尺度模型。此模型不但可以用来联合估计多个部分和器官相对于整体的异速生长指数,而且考虑了多个部分或组织器官之间的相互关系,大大方便了统计推断和实践应用。基于个体发育的异速生长是具有时间依从性的,因此个体的异速生长是用多元逐步回归分析整体与多个体成分和器官随着时间的改变量。异速生长尺度的联合分析法适用于分析那些具有相同或相似的多个生物学性状和功能,本文将通过对两个实例的分析来详细阐明。

多个部分相对整体异速生长的联合分析模型

根据异速生长的数学原理并考虑多个体成分或组织器官生长间的相互关系,首先提出联合分析多个体成分或组织器官相对整体异速生长的数学模型;联合异速生长模型更有利于比较不同体成分或组织器官间异速生长的差异,并有利于分析体成分或组织器官相对整体异速生长的遗传基础。采用多元线性逐步回归分析方法估计模型的参数,分析了一个关于肉牛屠体性状的实际数据集,验证了所构建模型及所建议方法的有效性。

热带云雾林植物功能性状对环境变化的年际响应

为了研究植物功能性状对环境变化的响应有助于理解植物对环境的适应策略,以海南热带雨林国家公园霸王岭片区的热带云雾林为研究对象,在2011年及2021年对21个20 m×20 m固定样地内DBH≥5 cm木本植物进行群落学调查,测定个体、物种和群落水平的植物功能性状及环境因子,分析植物功能性状和环境条件的变化,探讨环境因子对功能性状的影响规律.结果表明:(1)与2011年相比,2021年热带云雾林土壤全氮(TN)、有效氮(AN)含量显著增加,土壤有机质(SOM)、全磷(TP)、有效磷(AP)含量显著减少.空气最高温呈上升趋势,平均空气相对湿度、最低空气相对湿度呈下降趋势.对环境因子进行主成分分析,2011年负荷值较大的环境因子分别为土壤全氮、土壤全磷、土壤有效氮及最低空气相对湿度,2021年负荷值较大的环境因子为土壤有机质、土壤全磷、最高空气温度及最低空气相对湿度;(2)与2011年相比,2021年植物叶绿素含量和叶片厚度在个体水平显著增大,比叶面积显著减少;叶片厚度、叶绿素含量、茎全氮含量、叶片全氮含量在物种水平显著增大,茎可溶性糖含量、叶全磷含量显著减少;叶绿素含量、叶片厚度、茎全氮含量、茎全磷含量、叶全氮含量在群落水平显著增大,茎密度、茎可溶性糖含量、叶全磷含量显著减小;(3)多元逐步回归分析发现,土壤养分含量(如土壤有机质、全磷含量、有效氮含量等)和气候因子(如最高空气温度、最低空气相对湿度等)共同影响植物个体、物种及群落水平功能性状变化,土壤养分因子作用较大,土壤磷胁迫的加剧是影响各个群落组织水平功能性状变化关键因子.

An adaptive noise attenuation method for edge and amplitude preservation

Noise intensity distributed in seismic data varies with different frequencies or frequency bands; thus, noise attenuation on the full-frequency band affects the dynamic properties of the seismic reflection signal and the subsequent seismic data interpretation, reservoir description, hydrocarbon detection, etc. Hence, we propose an adaptive noise attenuation method for edge and amplitude preservation, wherein the wavelet packet transform is used to decompose the full-band seismic signal into multiband data and then process these data using nonlinear anisotropic dip-oriented edge-preserving fi ltering. In the fi ltering, the calculated diffusion tensor from the structure tensor can be exploited to establish the direction of smoothing. In addition, the fault confidence measure and discontinuity operator can be used to preserve the structural and stratigraphic discontinuities and edges, and the decorrelation criteria can be used to establish the number of iterations. These parameters can minimize the intervention and subjectivity of the interpreter, and simplify the application of the proposed method. We applied the proposed method to synthetic and real 3D marine seismic data. We found that the proposed method could be used to attenuate noise in seismic data while preserving the effective discontinuity information and amplitude characteristics in seismic refl ection waves, providing high-quality data for interpretation and analysis such as high-resolution processing, attribute analysis, and inversion.

全球跨界水合作的时空结构:领域变迁与尺度分异

在当前全球性淡水危机加剧、水冲突频发的背景下,跨界水合作成为化解水危机,实现国家间和平可持续发展的关键。利用跨界水条约数据,基于网络视角,从全球尺度、区域尺度与国家尺度对跨界水合作的时空结构进行研究。结论如下:(1)1820—2017年全球跨界水合作持续增多,覆盖范围明显扩大,合作领域从边界与水量向联合管理与水质保护转变,合作目的由以规管性为主导向规管性、程序性和原生性并进转变。多边合作与跨界地下水合作是当前全球跨界水合作的发展趋势。(2)同一时期五大洲跨界水合作发展进程与侧重领域存在较大差异;尽管全球跨界水合作网络涵盖的流域与国家日益增多,但其流域覆盖率仍较低。(3)1820—2017年全球跨界水合作网络大致经历了"网络形成—网络扩张—网络分化"三个阶段;欧洲国家间的跨界水合作联系相对较强,亚洲国家在跨界水合作网络中也愈发活跃,区域性与全球性并存是当前跨界水合作网络的重要特征。伴随着亚洲国家日益增长的跨界水合作需求,中国应充分发挥负责任的发展中大国的作用,加强与周边国家的跨界水合作,不断提升自身在全球跨界水资源合作领域的地位。

Large-scale circulation features associated with the heat wave over Northeast China in summer 2018

In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.

Anatomically realistic multiscale models of normal and abnormal gastrointestinal electrical activity

One of the major aims of the International Union of Physiological Sciences (IUPS) Physiome Project is to develop multiscale mathematical and computer models that can be used to help understand human health. We present here a small facet of this broad plan that applies to the gastrointestinal system. Specifically, we present an anatomically and physiologically based modelling framework that is capable of simulating normal and pathological electrical activity within the stomach and small intestine. The continuum models used within this framework have been created using anatomical information derived from common medical imaging modalities and data from the Visible Human Project. These models explicitly incorporate the various smooth muscle layers and networks of interstitial cells of Cajal (ICC) that are known to exist within the walls of the stomach and small bowel. Electrical activity within individual ICCs and smooth muscle cells is simulated using a previously published simplified representation of the cell level electrical activity. This simulated cell level activity is incorporated into a bidomain representation of the tissue, allowing electrical activity of the entire stomach or intestine to be simulated in the anatomically derived models. This electrical modelling framework successfully replicates many of the qualitative features of the slow wave activity within the stomach and intestine and has also been used to investigate activity associated with functional uncoupling of the stomach.

Pathways of mesoscale variability in the South China Sea

The propagation of oceanic mesoscale signals in the South China Sea(SCS) is mapped from satellite altimetric observations and an eddy-resolving global ocean model by using the maximum cross-correlation(MCC) method.Significant mesoscale signals propagate along two major bands of high variability.The northern band is located west of the Luzon Strait,characterized by southwestward eddy propagation.Although eddies are the most active in winter,their southwestward migrations,steered by bathymetry,occur throughout the year.Advection by the mean flow plays a secondary role in modulating the propagating speed.The southern eddy band lies in the southwest part of the SCS deep basin and is oriented in an approximately meridional direction.Mesoscale variability propagates southward along the band in autumn.This southward eddy pathway could not be explained by mean flow advection and is likely related to eddy detachments from the western boundary current due to nonlinear effects.Our mapping of eddy propagation velocities provides important information for further understanding eddy dynamics in the SCS.

Statistical Downscaling Prediction of Summer Precipitation in Southeastern China

A statistical downscaling approach based on multiple-linear-regression(MLR) for the prediction of summer precipitation anomaly in southeastern China was established,which was based on the outputs of seven operational dynamical models of Development of a European Multi-model Ensemble System for Seasonal to Interannual Prediction(DEMETER) and observed data.It was found that the anomaly correlation coefficients(ACCs) spatial pattern of June-July-August(JJA) precipitation over southeastern China between the seven models and the observation were increased significantly;especially in the central and the northeastern areas,the ACCs were all larger than 0.42(above 95% level) and 0.53(above 99% level).Meanwhile,the root-mean-square errors(RMSE) were reduced in each model along with the multi-model ensemble(MME) for some of the stations in the northeastern area;additionally,the value of RMSE difference between before and after downscaling at some stations were larger than 1 mm d-1.Regionally averaged JJA rainfall anomaly temporal series of the downscaling scheme can capture the main characteristics of observation,while the correlation coefficients(CCs) between the temporal variations of the observation and downscaling results varied from 0.52 to 0.69 with corresponding variations from-0.27 to 0.22 for CCs between the observation and outputs of the models.

Temporal and Spatial Variability of Dissolved Organic Carbon Concentration in the Xijiang River, South China

A whole year analysis of riverine dissolved organic carbon (DOC) concentrations in the Xijiang River (XJR), South China, showed that the mean riverine DOC concentration (1.24 mg L-1) in the XJR was notably lower than the averaged value (5.75 mg L-1) of the global riverine DOC concentration in several major rivers. There is an inconspicuous monthly fluctuation of the DOC signal in the XJR, but on a semi-yearly time scale, however, the riverine DOC concentration had significant difference between hydrological seasons. The DOC level during the flood season (1.18 mg L-1) was less than that during the non-flood season (1.40 mg L-1). Owing to the concomitance of the flushing and dilution effects of the runoff during the high-water period, the variation of riverine DOC concentration with discharge in the XJR differed from that reported in many other major rivers. The DOC export flux above the city of Wuzhou was about 0.62× 106 g C km-2 yr-1. The DOC transported during the "056" Massive Flood period comprised 30.35% of the annual total, while the discharge accounted for 36.32% of the total annual flow. The characteristics in riverine DOC concentration in the XJR were attributed to the combined effect of the geomorphologic, monsoon climatic and hydrological processes as well as land-use within the drainage basin.

Interannual Climate Variability of the Past Millennium from Simulations

The interannual variability of global temperature and precipitation during the last millennium is analyzed using the results of ten coupled climate models participating in the Paleoclimate Modelling Intercomparison Project Phase 3. It is found that large temperature(precipitation) variability is most dominant at high latitudes(tropical monsoon regions), and the seasonal magnitudes are greater than the annual mean. Significant multi-decadal-scale changes exist throughout the whole period for the zonal mean of both temperature and precipitation variability, while their long-term trends are indistinctive. The volcanic forcings correlate well with the temperature variability at midlatitudes, indicating possible leading drivers for the interannual time scale climate change.

Variability of Tropical Cyclone in High Frequent Occurrence Regions over the Western North Pacific

In this study, three high frequent occurrence regions of tropical cyclones(TCs), i.e., the northern South China Sea(the region S), the south Philippine Sea(the region P) and the region east of Taiwan Island(the region E), are defined with frequency of TC's occurrence at each grid for a 45-year period(1965–2009), where the frequency of occurrence(FO) of TCs is triple the mean value of the whole western North Pacific. Over the region S, there are decreasing trends in the FO of TCs, the number of TCs' tracks going though this region and the number of TCs' genesis in this region. Over the region P, the FO and tracks demonstrate decadal variation with periods of 10–12 year, while over the region E, a significant 4–5 years' oscillation appears in both FO and tracks. It is demonstrated that the differences of TCs' variation in these three different regions are mainly caused by the variation of the Western Pacific Subtropical High(WPSH) at different time scales. The westward shift of WPSH is responsible for the northwesterly anomaly over the region S which inhibits westward TC movement into the region S. On the decadal timescale, the WPSH stretches northwestward because of the anomalous anticyclone over the northwestern part of the region P, and steers more TCs reaching the region P in the greater FO years of the region P. The retreating of the WPSH on the interannual time scale is the main reason for the FO's oscillation over the region E.

Reduced Fidelity Susceptibility in One-Dimensional Transverse Field Ising Model

We study critical behaviors of the reduced fidelity susceptibility for two neighboring sites in the onedimensional transverse field Ising model. It is found that the divergent behaviors of the susceptibility take the form of square of logarithm, in contrast with the global ground-state fidelity susceptibility which is power divergence. In order to perform a scaling analysis, we take the square root of the susceptibility and determine the scaling exponent analytically and the result is further confirmed by numerical calculations.

Statistical Downscaling of FGOALS-s2 Projected Precipitation in Eastern China

A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project （CMIPS） the Representative Concentration Pathway （RCP） scenarios simulated by the second spectral version of the Flexible Global Ocean- Atmosphere-Land System （FGOALS-s2） model. Our val- idation results show that the downscaled time series agree well with the present observed precipitation in terms of both the annual mean and the seasonal cycle. The regres- sion models built from the historical data are then used to generate future projections. The results show that the en- hanced land-sea thermal contrast strengthens both the subtropical anticyclone over the western Pacific and the east Asian summer monsoon flow under both RCPs. However, the trend of precipitation in response to warming over the 21 st century are different across eastern Chi- na under different RCPs. The area to the north of 32°N is likely to experience an increase in annual mean precipitation, while for the area between 23°N and 32°N mean precipitation is projected to decrease slightly over this century under RCP8.5. The change difference between scenarios mainly exists in the middle and late century. The land-sea thermal contrast and the associated east Asian summer monsoon flow are stronger, such that precipitation increases more, at higher latitudes under RCP8.5 compared to under RCP4.5. For the region south of 32°N, rainfall is projected to increase slightly under RCP4.5 but decrease under RCP8.5 in the late century. At the high resolution of 5 km, our statistically downscaled results for projected precipitation can be used to force hydrological models to project hydrological processes, which will be of great benefit to regional water planning and management.

能源消费碳排放的影响因素特征及研究展望

碳排放影响因素是学术圈密切关注的重要研究方向,国内外学者开展了诸多案例研究并取得了丰富成果。因研究区社会经济发展水平、资源禀赋差异,不同学者在不同区域的研究结论不尽一致,缺少系统梳理和总结。有鉴于此,梳理国内外碳排放影响因素相关文献,基于文献综述,归纳碳排放影响因素特征。结果发现:(1)碳排放影响因素具有时间效应、空间效应和空间尺度效应,即碳排放影响因素的影响程度、作用方向,随时间演变、区域差异和研究单元的空间尺度升降而发生规律性变化。(2)碳排放影响因素的时间效应、空间效应和空间尺度效应,与中国短时间尺度内经济快速发展、经济发展水平存在区域差异、以及时间和空间尺度上经济发展水平的耦合相关。(3)碳排放影响因素特征对碳排放研究需立足区域发展方向、区域分类管控和空间降尺度提出客观要求。地域功能是自然承载力、社会经济水平和发展潜力的集成表达,城市、农业、生态功能区因在国土空间开发和保护格局中功能定位不同,其产业集聚和人口分布各有其特点,带来能源消费碳排放差异。以主体功能区为抓手、开展碳排放分类管控是重要的理论和实践尝试。

Nighttime anomaly of ionospheric electron density

The ionosphere is composed of a large number of electrons and ions, which are produced by the photoionization effect of the solar radiation on the neutral atmosphere. The altitude range of ionosphere is about 60–1000 km and varies with local time and other factors （e.g., solar and geomagnetic activity）. Although the ionosphere varies over multiply timescales, the diurnal variation is in the dominant position due to the sun’s photoionization effect.

Multi-scale inversion of density structure from gravity anomalies in Tarim Basin

Based on the power spectra of gravity anomalies in Tarim Basin, the anomalies can be decomposed to the following three components: a sub-anomaly formed mainly by the basin crystallized basement, a sub-anomaly formed mainly by deep sedimentary layers, and that by shallow sedimentary layers. A special wavelet transform analysis scheme and a density inversion method are designed and applied to the decomposition and inversion of gravity sub-anomalies, which are correlated with regional geology and drilling data. The results indicate that the deep and the shallow sub-anomalies show some relations with ancient fluid active zones. The negative density disturbances inversed from the shallow sub-anomaly are mainly caused by Mesozoic fluid active zones, whereas the negative density disturbances form the deep sub-anomalies are mainly correlated with Paleozoic fluid active zones. As the ancient fluid movement was good for formation of oil/gas fields, the multi-scale inversion methods for locating the ancient fluid movement zones seem to be helpful and valuable to oil/gas exploration.