中国入境旅游的经济增长效应与空间差异性研究

在旅游业与经济增长作用关系分析基础上,探究了旅游溢出理论,将其产生机制归纳为知识溢出、市场溢出和竞争效应3个方面。实证分析中,构建了包括入境旅游、物质资本、人力资本、科技创新和对外开放的分析框架,运用中国大陆31个省域2000~2014年面板数据对入境旅游的经济增长效应进行实证检验。全局分析得出中国入境旅游在邻近省市以集聚与合作为主,邻近省域入境旅游发展对本地经济增长具有辐射带动作用,且这种空间溢出效应大于直接效应;入境旅游业发达的地区,入境旅游的经济增长效应更大。局部分析发现,随着入境旅游的发展,入境旅游的经济增长效应不断强化,中部部分地区提升幅度最大;入境旅游的经济增长效应存在空间差异性,东部沿海地区贡献最大,西北地区相对最小。     

A discrete global grid system for earth system modeling

To support Earth system modeling, we propose a discrete global grid system that expresses multi-resolution spatial data. Specifically, a unified coding model that expresses a grid of nodes, edges, and cells is constructed for a triangular discrete global grid system. To fulfill the requirements of practical applications, we design a code-based topological query method for this grid system and an algorithm to transform between grid codes and geographic coordinates. We evaluate the Global Finite Volume Community Ocean Model (Global-FVCOM) on the triangular discrete global grid system in the proposed uniform coding model. The ocean tidal waves simulated by the Global-FVCOM running on the coded grid are then compared with results obtained using a traditional irregular spherical grid system, and the results display comparable accuracy. The uniform coding model proposed in this paper provides a triangular discrete global grid system that can represent multi-resolution spatial data and can be used in Earth system models. This unified coding model can also be applied to the geographic coordinate system made up of latitudes and longitudes, as well as diamond and hexagonal grids.     

地铁对服务业集聚的影响 ——以广州市为例

以广州市为例,基于POI数据,运用SAR模型识别城市地铁开通对服务业集聚的影响.研究发现:服务业集聚具有显著的空间依赖性特征,本地服务业集聚会受到周边地区服务业集聚的影响;开通地铁对广州市服务业空间集聚产生显著的正向影响,可提高城区的服务业集聚水平,但这种集聚效应因行业不同而有所差异;地铁开通对批发与零售业、住宿与餐饮...     

Evaluation of global climate model on performances of precipitation simulation and prediction in the Huaihe River basin

Using climate models with high performance to predict the future climate changes can increase the reliability of results. In this paper, six kinds of global climate models that selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Path (RCP) 4.5 scenarios were compared to the measured data during baseline period (1960–2000) and evaluate the simulation performance on precipitation. Since the results of single climate models are often biased and highly uncertain, we examine the back propagation (BP) neural network and arithmetic mean method in assembling the precipitation of multi models. The delta method was used to calibrate the result of single model and multimodel ensembles by arithmetic mean method (MME-AM) during the validation period (2001–2010) and the predicting period (2011–2100). We then use the single models and multimodel ensembles to predict the future precipitation process and spatial distribution. The result shows that BNU-ESM model has the highest simulation effect among all the single models. The multimodel assembled by BP neural network (MME-BP) has a good simulation performance on the annual average precipitation process and the deterministic coefficient during the validation period is 0.814. The simulation capability on spatial distribution of precipitation is: calibrated MME-AM > MME-BP > calibrated BNU-ESM. The future precipitation predicted by all models tends to increase as the time period increases. The order of average increase amplitude of each season is: winter > spring > summer > autumn. These findings can provide useful information for decision makers to make climate-related disaster mitigation plans.     

安徽齐云山丹霞地貌成因

According to the study of some local scholars (Peng Hua et al., 2000), over 400 sites of Danxia landform have been already discovered in China. Chen Guoda (1935), Zeng Zhaoxuan et al. (1978), Huang Jin et al. (1992; 1994; 1996) and Peng Hua et al. (1998; …     

纪念竺可桢教授对沙漠研究的贡献(摘要)

沙漠学是一门新兴的学科,它的成长与发展是和竺可桢教授的指导与关怀分不开的,至今我们沙漠科学工作者十分怀念他。竺可桢教授在沙漠科学研究中的主要贡献有四个方面: 一、明确指出了"改造沙漠是我们的历史任务",25年来沙漠研究的实践证明了他的论断。沙漠科学要发展就必须要密切连系国家经济建设,要和沙漠治理的实践相结合。     

河西走廊西端灌丛沙丘发育过程及其对沙漠化的指示意义

在风沙活动强烈的荒漠地区开展环境变化研究常缺乏符合要求的地质测年材料。灌丛沙丘是干旱区发育的一种特殊生物地貌类型,具有计年和储存环境信息的功能,可以用来重建沙丘的发育过程和过去的环境变化。以河西走廊西端花海盆地发育的灌丛沙丘沉积剖面为研究对象,基于AMS¹⁴C年代学及沉积物粒度、碳酸盐含量、地球化学元素等代用指标的分析,与文献记载、沙漠化监测数据和近几十年的器测气象资料对比分析,试图揭示区域灌丛沙丘的发育过程及其环境指示意义。结果表明：花海盆地灌丛沙丘的发育时间已超过800 年;20世纪60年代中后期至70年代早期人类活动的干扰曾使灌丛沙丘的堆积过程中断,但丰富的物源随后又促使灌丛沙丘再次快速发育。沙丘物源曾发生过剧烈的变化,使得灌丛沙丘沉积物中的粗颗粒组分和中值粒径并不适于作为环境代用指标重建区域的风沙环境变化,而细颗粒组分（<63 μm和<10 μm）和碳酸盐含量的变化,则揭示了研究区在20世纪70-80年代（沙丘高度300~420 cm）时获得了丰富的物质来源。灌丛沙丘沉积物中的Zr/Rb比值,能够作为良好的环境代用指标指示1970-1988年（沙丘高度300~420 cm）区域处在风沙活动较强烈的环境;近几十年花海盆地土地沙漠化明显,尤其是20世纪70年代和80年代。灌丛沙丘可以作为有较高可信度的地质记录载体,在河西走廊西端重建较长时间尺度的、高分辨率的区域气候环境演变历史。     

短期增温和降水减少对沙质草地土壤微生物量碳氮和酶活性的影响

通过模拟气候变化,探究短期增温和降水减少对沙质草地土壤微生物量碳氮及酶活性的影响,揭示沙质草地土壤微生物量碳氮和酶活性对短期气候变化的响应规律。结果表明：（1）短期增温和降水减少对土壤微生物量碳氮和酶活性均产生显著影响。（2）在自然温度下,与自然降水相比,降水减少40%时土壤微生物量碳（MBC）和微生物氮（MBN）含量最高,增幅分别为87.9%和98.8%;降水减少60%时土壤碱性蛋白酶（S-ALPT）活性最低,降幅达32.8%。（3）在增温条件下,与自然降水相比,降水减少40%时土壤MBC和MBN含量最低,降幅分别为25.67%和48.16%,土壤脲酶（S-UE）活性最高,增幅20.42%。（4）土壤pH与3种土壤酶活性正相关,与土壤微生物量碳氮负相关。土壤微生物量碳氮与土壤纤维素酶（S-CL）活性负相关,与S-UE、S-ALPT活性正相关。     

日照市海水入侵现状与治理方案

通过遥感解译对日照市海水入侵现状进行分析,对海水入侵程度进行评价,发现养殖池和河滩面积在大幅增加,盐田、滩涂、沙滩等均在减少。在日照沿海地区,地下水的储备与人类的用水需求之间存在矛盾,人类过量开采地下淡水是产生海水入侵的主导因素。建议采取兴建地下水库、减少地下水开采和人工回灌等措施防治海水入侵。