A proportional odds model of human mobility and migration patterns

The modelling of human mobility and migration patterns has received much attention due to its substantial importance. Despite long-term efforts, we still lack a modelling framework that captures mobility patterns and further obtains a prospective view of movement trends with regards to diverse impacting factors. Here, we propose a proportional odds model of human mobility and migration (POM-HM) that takes a probabilistic approach to model human movements. Our model is based on the migration probability with a log-logistic distribution under the proportional odds assumption. Explanatory variables are introduced into the model by re-parameterizing the probability distribution function. The two resultant functions, namely, the migration strength and cumulative hazard, are used to estimate regional differences among travel fluxes and their tendencies. The performance of the POM-HM in terms of its validity and accuracy is examined and compared with the gravity model and the radiation model. The probability-based modelling framework enables us to investigate regional variations in migrant fluxes consequently further predict potential future patterns. In short, our modelling approach captures the probabilistic nature of human mobility and migration and furthers our understanding of both the spatiotemporal patterns of population movements and the impacts of various driving forces.     

Blooms of Prorocentrum donghaiense reduced the species diversity of dinoflagellate community

Most of reported harmful algal blooms(HABs)of microalgae(75%)have been caused by dinoflagellates.Studies on the negative effects of HABs have generally focused on animals,valuable organisms in particular,and environmental factors such as dissolved oxygen and nutrients,but relatively fewer on community level,particularly that using metagenomic approach.In this study,we reported an investigation on the effects of a HAB caused by the dinoflagellate Prorocentrum donghaiense on the species diversity and community structure of the dinoflagellate sub-community via a pyrosequencing approach for the samples taken before,during,and after the bloom season of P.donghaiense in the East China Sea.We sequenced partial 28S rRNA gene of dinoflagellates for the field samples and evaluated the species richness and diversity indices of the dinoflagellate community,as a sub-community of the total phytoplankton.We obtained 800185 valid sequences(categorized into 560 operational taxonomic units,OTUs)of dinoflagellates from 50 samples and found that the biodiversity of dinoflagellate community was significantly reduced during the blooming period in comparison to that in pre-and after-blooming periods,as reflected in the four diversity indices:the species richness expressed as the number of OTUs,Chao1 index,Shannon index(evenness),and Gini-Simpson index.These four indices were all found to be negatively correlated to the cell density of the bloom species P.donghaiense.Correlation analyses also revealed that the P.donghaiense cell abundance was correlated negatively with NO3--N,and NO2--N,but positively with total nitrogen(TN)and total phosphorus(TP).Principal coordinates analysis(PCoA)showed that the community structure of dinoflagellates was markedly different among the different sampling periods,while the redundancy analysis(RDA)revealed P.donghaiense abundance,salinity,NO3--N,and SiO32-were the most four significant factors shaping the dinoflagellate community structure.Our results together demonstrated that HABs caused by the dinoflagellate P.donghaiense could strongly impact the aquatic ecosystem on the sub-community level which the blooming species belongs to.     

陀螺全站仪在地下工程贯通测量中的应用

对地下工程贯通测量的工作特点和包含的内容做了介绍,阐述了陀螺全站仪的工作原理和在进行地下工程测量时其方向传递原理。本文以HGG05陀螺全站仪在地铁工程中的应用为例,探讨陀螺全站仪在地下贯通测量中的作用,论证该技术能有效地提升地下隧道的贯通精度,实现隧道的顺利贯通。     

奎玛地区“5·27”冰雹天气的雷达回波分析

通过对奎玛地区 2000年 5月 27日 711数字化雷达观测资料的分析,得出此次影响该地区的冰雹天气的路径,强度、回波特征,对该地区雹暴天气的形成、演变及其防御措施有进一步的了解。     

甘蔗品种性状与过氧化物酶同工酶的关系

以３０个甘蔗栽培品种为材料,用垂直平板聚丙烯酰胺凝胶电泳方法,对过氧化物酶同工酶进行分析,统计比较各酶带出现的频率与甘蔗主要性状的关系．结果表明：Ａ６、Ｂ３酶带同时出现时１００％为高糖品种,因此Ａ５、Ｂ３酶带与高糖性状关系极为密切;Ａ６、Ａ８、Ｂ３、Ｂ７酶带单独存在时也与高糖性状有关;早熟种与Ａ５、Ｂ３、Ｂ７酶带的存在有关;中小茎种和中茎种分别与Ａ４、Ｂ５酶带的存在有关。     

地理过程的案例表达与组织——以南海区海洋涡旋为例

案例模型是基于案例推理方法(CBR)的推理基础,而时空数据模型是地理信息系统时空表达的概念基础。基于案例的推理方法应用于地理领域,案例表达则不能仅采取传统的表示方法,需要结合地理问题的特点;但时态地理信息系统(T-GIS)的时空数据模型又不能直接采用,需要考虑地理案例表达和推理的需求。通过对地理案例应用的分析和时空过程特点的总结,提出分级描述框架的地理案例时空过程概念表达模型,并构建其物理表达模型。本文以中国南海海洋涡旋为例进行了验证,表明此模型可应用于具有完整生命周期且变化是连续渐进地理现象的研究。     

Integration technology research on marine geographical information system

It is urgent and necessary to integrate a marine geographical information system （MGIS） with marine remote sensing detection modules. On the basis of the current technology and features of applications, an open three-layer integration framework is designed. At the data layer, a two-level three-base integration mechanism based on the plug-in technology is applied; At the function layer, an integration mode based on API, DLL, EXE and COM is discussed; and at the application layer, a sharing mechanism based on the clients/service is adopted. As an example, the remote sensing integrated application information system of China＇s coastal zone and offshore （MaXplorer1. 0） with muhiecology remote sensing fusion and assimilation module, surge detection module as well as eight other thematic application modules is integrated, and the key technology of integration is discussed at different layers and in different modules. The result shows that it is possible to realize the conformity of technology and resources and to provide the incorporate technology platform for marine information operational functioning after applying the integration framework.     

基于ArcGIS的地震活断层多源数据组织与管理研究

"中国地震活动断层探测技术系统"获取的全国20多个重点城市多源地震探测数据,旨在满足城市地震抗震设防的空间数据基础建设以及城市发展规划、土地利用、重大工程选址应用的迫切需求,分析不同来源的地震探测数据特征,建立中国活动断层探测与地震危险性评价数据库的概念模型。在此概念模型上,结合ArcGIS的GeoDatabase模型给出了城市活动断层探测数据库具体逻辑模型,并按照地震系统确定的活动断层信息管理系统与基础数据库统一的建库标准和数据规范,实现多种活断层探测数据的统一整理和装载入库,完成了全国多个重点城市的活断层探测多源数据库建设,为"中国地震活动断层探测技术系统"各分工程的实施提供了数据保障和数据服务。     

Analysis of ecological quality in Lhasa Metropolitan Area during 1990–2017 based on remote sensing and Google Earth Engine platform

Based on a total of 519 images,the composite images with the lowest possible cloud cover were generated at pixel level with image synthesis method on Google Earth En-gine(GEE)platform.The Remote Sensing Ecological Index(RSEI)was adopted,and calcu-lated in an efficient way with the assistance of parallel cloud computing of the GEE platform.The RSEI was used in this paper to evaluate and monitor the eco-environmental quality of the Lhasa Metropolitan Area.Results show that:(1)The ecological quality is better in the west than in the east of Lhasa Metropolitan Area,with Lhasa as an approximate dividing point.The ecological quality improved and then deteriorated dramatically before 2000,with the mean RSEI value dropping from 0.51 to 0.46;the trend was followed by a gradual increase up until 2017,with the mean RSEI value increased from 0.46 to 0.55.(2)The RSEI is weakly and positively correlated with socioeconomic indicators.This indicates that the population growth and economic development did not negatively influence the ecological quality,but actually boosted it.(3)The GEE can serve as an efficient computing platform for the assessment and monitoring of eco-environmental quality in vast regions.     

Population migration across the Qinghai-Tibet Plateau: Spatiotemporal patterns and driving factors

Developing a comprehensive understanding of inter-city interactions is crucial for regional planning.We therefore examined spatiotemporal patterns of population migration across the Qinghai-Tibet Plateau(QTP)using migration big data from Tencent for the period between 2015 and 2019.We initially used decomposition and breakpoint detection methods to examine time-series migration data and to identify the two seasons with the strongest and weakest population migration levels,between June 18th and August 18th and between Oc-tober 8th and February 15th,respectively.Population migration within the former period was 2.03 times that seen in the latter.We then used a variety of network analysis methods to examine population flow directions as well as the importance of each individual city in migra-tion.The two capital cities on the QTP,Lhasa and Xining,form centers for population migra-tion and are also transfer hubs through which migrants from other cities off the plateau enter and leave this region.Data show that these two cities contribute more than 35％of total population migration.The majority of migrants tend to move within the province,particularly during the weakest migration season.We also utilized interactive relationship force and ra-diation models to examine the interaction strength and the radiating energy of each individual city.Results show that Lhasa and Xining exhibit the strongest interactions with other cities and have the largest radiating energies.Indeed,the radiating energy of the QTP cities cor-relates with their gross domestic product(GDP)(Pearson correlation coefficient:0.754 in the weakest migration season,WMS versus 0.737 in the strongest migration season,SMS),while changes in radiating energy correlate with the tourism-related revenue(Pearson correlation coefficient:0.685).These outcomes suggest that level of economic development and level of tourism are the two most important factors driving the QTP population migration.The results of this analysis provide critical clarification guidance regarding huge QTP development dif-ferences.