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1.
Phytolith analysis from the archaeological site of Kush, Ras al-Khaimah, United Arab Emirates 总被引：1，自引：0，他引：1
Sachiko Ishida Adrian G. Parker Derek Kennet Martin J. Hodson 《Quaternary Research》2003,59(3):310-321
Despite the wealth of archaeological sites and excellent conditions for preservation, few phytolith investigations have been undertaken from the Arabian Gulf region. The results from the Sasanian and Islamic archaeological tell of Kush, Ras al-Khaimah, United Arab Emirates, are presented. Kush is situated just inside the Gulf on an important trade route. The occupation sequence dates from the 4th century A.D. until the 13th century A.D., recording the development of the site in the Sasanian period, followed by the arrival of Islam in the 7th century A.D. and the final abandonment of the site in the late 13th century when the nearby site of al-Mataf (Julfar) began to develop closer to the present day coastline. All the samples analyzed contained abundant phytoliths (short cells, elongated cells, and groups of elongated cells) of various types. They included date palm (Phoenix dactylifera), papillae (possibly from barley (Hordeum)), and hair cells possibly from species of canary grass (Phalaris spp.). Some researchers have suggested that groups of elongated cells may indicate the presence of irrigation in semiarid environments. The present results for this class of phytoliths appeared to imply that intensive irrigation was unlikely to have taken place around Kush. 相似文献
2.
针对2015年2月12—16日发生在东亚的一次预报过度的温带气旋开展了资料同化及资料影响性观测等研究。此次温带气旋的发展与各个主要数值模式的预报相差甚大,并未出现预期中的爆发性增长。针对此次过程,采用WRF模式及其变分同化系统开展了模拟与同化试验,主要同化了NCEP全球地面和高空观测资料,修正了此次温带气旋过度预报的问题。经过同化后,减弱了系统的气旋性环流,同时南北温差的减弱也导致了环境场的斜压性的减弱,使得气旋爆发性增长延后,强度减弱,更符合实际观测。与此同时,还利用WRF伴随模式WRFPLUS和观测资料影响性模式WRFDA-FSO开展了观测资料影响性的研究,并发现三类资料SOUND、SYNOP、GEOAMV在减小预报误差中的作用最大。进一步的敏感性试验表明仅同化这3种资料可以取得更为理想的预报。 相似文献
3.
Roland Schmidt Christian Kamenik Christina Kaiblinger Markus Hetzel 《Journal of Paleolimnology》2004,32(2):177-196
Diatom abundances in the surface sediment samples of 41 mountain lakes in the central Austrian Alps (Niedere Tauern) were related to environmental variables using multi-variate techniques. Canonical correspondence analysis (CCA) revealed that the pH, date of autumn mixing (A
mix), mean August water temperature (T
Aug), dissolved organic carbon (DOC), and relative water depth (Z
rel) made significant contributions to explain the diatom assemblage variation in the lakes of the training set. A weighted averaging partial least square regression and calibration model was used to establish Di-pH (R
2
boot= 0.72, RMSEPboot= 0.131), and a thermistor measurements-based PLS model for A
mix (R
2
boot= 0.71, RMSEPboot= 0.006 log10 Julian days). The latter showed a better prediction than T
Aug, and was used in terms of climate change. These transfer functions, together with analyses of loss on ignition (LOI), the total carbon/nitrogen (C/N)-ratios, and selected pollen, were applied to an early to mid-Holocene (11.5–4 cal. ky BP) sediment core section from an Austrian Alpine treeline lake on crystalline bedrock. Additionally, passive sample scores in the CCA of the diatom training set were used to show trends in the variables DOC and Z
rel. During the early Holocene, diatoms indicative of increased pH, extended warm summers, and low water levels dominated. Between 10.2 and 7.6 cal. ky BP it was followed by diatom assemblages that indicated an increase in lake water depth and an earlier A
mix. The multi-proxy data suggest that the A
mix decline is the result of a series of snow-rich summer cool and wet climate fluctuations, which were divided by climate warming at ∼9 cal. ky BP. Increased A
mix, LOI and DOC, and the correspondent decline in the C/N-ratios, show subsequent climate warming between 7.3 and 6 cal. ky BP. The long-term trend in Di-pH indicates the impact of catchment-related processes during the early-Holocene, that were superimposed by climate. 相似文献
4.
湘西北地区石漠化遥感调查的技术方法 总被引：2，自引：0，他引：2
应用20世纪70年代末和90年代末TM卫星数据,综合运用ENVI、PHOTOSHOP、MAPGIS、ARC/INFOGIS等遥感图像处理与应用软件,通过石漠化训练样区的选择、监督分类、矢量化和数据转换等步骤,实现了石漠化的自动分类与专题图件制作。将分类石漠化图按2 mm×的网格进行网格化,依据石漠不关心化所占网格总面积的比例进行归并、筛选,面积>2mm以上的网格单元合并为石漠化区;面积～的网格单元合并为轻度石漠化区;面积<70%70%50%的网格单元合并为非石漠化区。调查表明:湘西北地区近内,石漠化区总面积增加了约50%20a300km2平均每年增加约,15km2,即所占比例由增加到约。0.54%1.60% 相似文献
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6.
Based on historical records, Jesuit missionaries were the first to introduce date palm (Phoenix dactylifera L., Arecacea) to the mission oases of the Mexican Baja California peninsula. Seedling date palms readily naturalized and have partially, and in some cases almost entirely replaced the native fan palm, Washingtonia filifera and Washingtonia robusta in the oases. These wild and introduced palms form the over-story for smaller cultivated trees, shrubs, and open gardens of mixed perennial and annual cultivars in complex agro-ecosystems. They also grow in dense stands along the oases arroyos where they may be “owned” by various oasis residents and semi- to carefully managed, or comprise wild populations beyond the periphery of the oasis settlements. These palms serve as ecological and cultural keystone species, altering oasis microclimates and providing shade for understory crops, shelter and food resources for resident and migratory fauna, and building materials and food for oasis human residents. I explore the agro-ecological role of the date palm in Baja California peninsula oases. 相似文献
7.
Mohammed Danish Rokiah Hashim Mohd Rafatullah Othman Sulaiman Anees Ahmad Govind 《洁净——土壤、空气、水》2011,39(4):392-399
This study reports on the adsorption characteristics of Pb(II) ions from aqueous solutions using ZnCl2‐activated date (Phoenix dactylifera) bead (ADB) carbon with respect to change in adsorbent dosage, initial pH, contact time, initial concentration, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo‐second‐order kinetic model. Thermodynamic parameters, enthalpy change (ΔH° = 55.11 kJ/mol), entropy change (ΔS° = ? 0.193 kJ/mol/K), and Gibbs free energy change (ΔG°) were also calculated for the uptake of Pb(II) ions. These parameters show that adsorption on the surface of ADB was feasible, spontaneous in nature, and endothermic between temperatures of 298.2 and 318.2 K. The equilibrium data better fitted the Langmuir and Freundlich isotherm models than the D–R adsorption isotherm model for studying the adsorption behavior of Pb(II) onto the ADB carbon. It could be observed that the maximum adsorption capacity of ADB was 76.92 mg/g at 318.2 K and pH 6.5. 相似文献
8.
本文分析和介绍了在西门子计算机上开发研制的一种GPS数据后处理软件包GPSPPS。该软件包可进行GPS原始盒式磁带数据的解码、分流和数据的预处理以及测站点空间坐标的求解,在采用不同的接收机采集的数据时,可以进行数据格式的标准变换;通过IBMPC机与西门子的通讯连接实现盒带数据到西门子的转录。最后,利用该软件对国内一次TI—4100观测试验进行了分析处理,给出了试验结果,得出了一些有益的结论。 相似文献
9.
本文简要介绍了厦门地震台地倾斜观测数据处理系统开发的背景及主要功能、技术要点等 ,并通过实例展现了本系统的强大图形功能。 相似文献
10.
随着数字化测图广泛推广,数字产品的检查工作加大,为了减少检查工作,提高检查质量,对此开发了数字化地形图检查软件。此软件对野外采集数据处理和地形图数据检查进行了探讨,对广大软件开发者具有积极的借鉴作用。 相似文献