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排序方式: 共有86条查询结果,搜索用时 15 毫秒
1.
It is shown that a gas of massive bosonic particles (m
60 eV), e.g. Higgs particles, surrounding disk galaxies is able to generate the flat rotation curves of spiral galaxies without internal difficulties with physical principles. We have analyzed 36 galaxies and find good agreement with the empirical data. 相似文献
2.
A Hydrologic Budget Analysis for the Nile Valley in Egypt 总被引:3,自引:0,他引:3
3.
Saed Khayat Peter Möller Stefan Geyer Amer Marei Christian Siebert Fayez Abu Hilo 《Environmental Geology》2009,57(8):1739-1751
The spatial and temporal changes of the composition of the groundwater from the springs along the Wadi Qilt stream running
from the Jerusalem–Ramallah Mountains towards the Jericho Plain is studied during the hydrological year 2006/2007. The residence
time and the intensity of recharge play an important role in controlling the chemical composition of spring water which mainly
depends on distance from the main recharge area. A very important factor is the oxidation of organics derived from sewage
and garbage resulting in variable dissolved CO2 and associated HCO3
− concentration. High CO2 yields lower pH values and thus under-saturation with respect to calcite and dolomite. Low CO2 concentrations result in over-saturation. Only at the beginning and at the end of the rainy season calcite saturation is
achieved. The degradation of dissolved organic matter is a major source for increasing water hardness. Besides dissolution
of carbonates dissolved species such as nitrate, chloride, and sulfate are leached from soil and aquifer rocks together with
only small amounts of Mg. Mg not only originates from carbonates but also from Mg–Cl waters are leached from aquifer rocks.
Leaching of Mg–Cl brines is particularly high at the beginning of the winter season and lowest at its end. Two zones of recharge
are distinguishable. Zone 1 represented by Ein Fara and Ein Qilt is fed directly through the infiltration of meteoric water
and surface runoff from the mountains along the eastern mountain slopes with little groundwater residence time and high flow
rate. The second zone is near the western border of Jericho at the foothills, which is mainly fed by the under-groundwater
flow from the eastern slopes with low surface infiltration rate. This zone shows higher groundwater residence time and slower
flow rate than zone 1. Groundwater residence time and the flow rate within the aquifer systems are controlled by the geological
structure of the aquifer, the amount of active recharge to the aquifer, and the recharge mechanism. The results of this study
may be useful in increasing the efficiency of freshwater exploitation in the region. Some precautions, however, should be
taken in future plans of artificial recharge of the aquifers or surface-water harvesting in the Wadi. Because of evaporation
and associated groundwater deterioration, the runoff water should be artificially infiltrated in zones of Wadis with high
storage capacity of aquifers. Natural infiltration along the Wadis lead to evaporation losses and less quality of groundwater. 相似文献
4.
5.
Ambreen Ghalib Sahar Mirza Danish Raza Ainnee Rafi Farhan Ali 《Transactions in GIS》2023,27(5):1318-1337
The key objective of the study is to collect the factors which play an important role in the city's sustainability and implementation advantages for the development of cities in future. This article develops an urban sustainability assessment framework by giving GIS-based decision support tools to guide cities toward sustainability. Multicriteria analysis was used as the decision support system and provides an analytical framework for assessing differences in the level of criteria and ranking decision options. It has the capability for assessment of urban sustainability because it brings sustainability criteria from three pillars of sustainability, environmental, social, and economic, which provide an integrated approach for assessment of urban sustainability. The GIS-based multicriteria analysis serves as a sustainability support system that maps urban sustainability and the underlying environmental, social, and economic conditions. The results from the study show that the four cities - Faisalabad, Lahore, Gujranwala, and Multan - have better economic conditions while only Lahore and Faisalabad showed social progress and the remaining cities showed less suitability. For the environmental index, none of the cities attained high suitability. Lahore, Faisalabad, and Rawalpindi showed better conditions than Gujranwala and Multan. It is demonstrated that Punjab cities have made progress in economic condition and improvement in social condition but have poor environmental condition. In the study, the environmental dimension has indicators which have more impact on the urban sustainability. Environmental degradation is observed in all selected regions and not a single region showed suitability toward its environmental condition and due to this none of the cities gained suitable scores for urban sustainability. Consequently, urban sustainability is a multidimensional and dynamic process that needs regular evaluation and monitoring. Thus, this article contends that the tools help to highlight and emphasize those areas that need guidance in achieving urban sustainability. 相似文献
6.
Muhammad Rafique Saeed Ur Rahman Muhammad Akram Matiullah 《Environmental Earth Sciences》2012,66(4):1225-1232
This paper presents the results of indoor radon concentration measurements in 120 dwellings of district Sudhnuti of Azad Kashmir. Measurements were taken with CR-39 passive alpha track detector. CR-39 based box type radon detectors were installed in a bedroom and living rooms of each house. The detectors were retrieved after exposing to indoor radon for period of 6 months and then etched in 6 M NaOH at 80°C for 16 h, the observed track densities were converted in to the indoor radon concentration. Indoor radon concentration varied from 20 ± 12 to 170 ± 4 Bq m−3 for the houses of the district Sudhnuti. Arithmetic mean (AM), geometric mean (GM) and geometric standard deviations (GSD) were found to be 82 ± 6, 77 ± 6 and 1.51, respectively. The minimum value of weighted average radon concentration was recorded in one of the house of Mang town, whereas the maximum value was found in the Pattan Sher Khan region. Doses due to indoor radon exposure vary from 0.50 ± 0.31 to 4.28 ± 0.11 mSv year−1 AM, GM and GSD. of mean effective doses were found to be 2.06 ± 0.13, 1.95 ± 0.18 and 1.51, respectively. According to the recommendations made by the Health Protection Agency, UK (200 Bq m−3) all the houses surveyed are within the safe limits. 相似文献
7.
Resilience assessment on coastline changes and urban settlements: A case study in Seribu Islands, Indonesia 总被引:1,自引:0,他引:1
The sustainable development in the ocean and costal areas has been an issue for the archipelago nation. Since two decades ago, some archipelago nations have attempted to implement the concept of both scientifically and politically sounding sustainability. The vulnerability assessment is one of the methods that are being used to measure the ocean and coastal sustainability in order to have better evaluation and redesign of the land development as well as policy making. Most of the vulnerability assessment has been conducted based on pressures, damages and changes that involve in the region. A common understanding of the vulnerability assessment is that there are three aspects to be considered: hazards, resilience and damages. These three aspects must be well defined at first in order to have better indicators or sub-indices for the vulnerability index. There are several issues and factors that should be considered before performing the vulnerability assessment. Firstly, each country has different coastal characteristics due to a different geologic process. Secondly, the three aspects of the vulnerability (i.e. hazards, resilience and damages) are impacting on each country at a different scale. Thirdly, the vulnerability of a small island region is different from that of a large island region. Finally, policies and regulations vary in each country.From the data analysis results, it is found that the urban settlement in Seribu Islands is one of the resilient factors in addition to the geological and geomorphological conditions. The resilience factors in Seribu Islands are classified into four categories: 1) settlements area, 2) population density, 3) hard infrastructure such as airfields, ports and roads, 4) geological process such as abrasion and erosion. Based on the island characteristics of Seribu Islands, a unique vulnerability index that fits to this locality is developed. It is shown that the vulnerability index developed in this study can measure the resilience of Seribu Islands. In addition to the aforementioned resilience factors, the unique geographical condition and the geological stability in Seribu Islands made the outer islands become a barrier from oceanographic conditions and made the inner islands protected. However, the population growth made significant changes in terms of ecology, water, sanitation and pollution within the region. 相似文献
8.
9.
Thamer Khazal Al-Ameri Sahar Y. Jasim Amer J. S. Al-Khafaji 《Arabian Journal of Geosciences》2011,4(5-6):945-972
Six sections of 1–2.7-m depth contain ten sediment samples, each collected from the caves of Shanidar, Hawdian, and Hazar Merd with the nearby river valley sites of Zawi-Chemi, Gawra River, and Barda Balka, respectively, in North Iraq. They have been analyzed palynologically for their climatic significance and vegetational cover during late Quaternary in northeastern Iraq. The main information gathered from these palynological analyses as well as stone tools is ancient open site settlements in Barda Balka of Paleolithic interglacial Acheuleon culture. During the last Ice Age (120,000–10,000 years before present (B.P.)) people refuged to cave settlements. Baradost Mountain as well as the Aqra and Piera Maqroon mountains cavemen of the Middle Paleolithic Period are related to steppe vegetation with cold climate and glacial storms. Those cavemen manufactured stone artifacts of Mousterian to Gravetian culture and have their own religious belief and funeral ceremony especially recorded in the Shanidar cave. They lived by hunting and food collecting from a nearby valley to each cave. During earliest Holocene time (10,000 years B.P.), changing climate to moderately warm climate with Quercus forests and poacean vegetation was recorded, and the cavemen evolved to Neolithic culture and hence moved to settle in plain areas and built the oldest villages of the world, viz., Zawi-Chemi and Jarmo with continuing temporarily living in the caves as well. Their habit changed from food collectors to farmers who cultivated the land with wheat, barley, fruits, olive, legumes, and flowers of brilliant colors, nice odor, and nectariferous as well as domesticated animals for their food resources. Clay tablets of the Sumerians, Babylonians, and Assyrians have documented (Arapha) Kirkuk as one of their cities since 5,500 years B.P. The stone writing records of Assyrian king Sennacherib (705–681 years B.C.) state of making irrigation canals flowing to the temple of Ishtar in Erbil. On the other hand, the similarity of Jarmo village in the present Kurdstan region of Iraq to ancient Tell Hassuna village, south of the present Mosul city (within ancient Nineva city), and the pottery of Jarmo villages to Nineva pottery could give evidence for Jarmo people as followers to the Babylonian–Assyrian cultures within their empire and to prove that people of North Iraq and South Iraq are interrelated cultures through the history within Mesopotamian cultures. 相似文献
10.
Although evidence for Quaternary environmental changes in the Arabian Peninsula is now growing, research has mostly been conducted in the United Arab Emirates (UAE) and in the Sultanate of Oman. There have been virtually no recent studies in Saudi Arabia, especially in the central region such as around Al‐Quwaiayh. In this area there are a series of outwash plains developed along the eastern edge of the Arabian Shield that formed in the late Quaternary. Four sedimentary sections, which are representative of the deposits that have accumulated, have been studied and five luminescence ages obtained. These are the first luminescence ages acquired from Quaternary sediments in central Saudi Arabia. The preserved fluvial deposits in the study area have formed during humid events at ca. 54 ka, ca. 39 ka and ca. 0.8 ka. In more recent times aeolian sands have been encroaching on to the distal parts of the outwash plains. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献