首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10篇
  免费   0篇
测绘学   3篇
地质学   4篇
海洋学   2篇
天文学   1篇
  2018年   2篇
  2013年   2篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  1996年   1篇
  1990年   1篇
  1982年   1篇
排序方式: 共有10条查询结果,搜索用时 31 毫秒
1
1.
The design of single-point, subsurface moorings is carried out a present by a design engineer with the help of some computer programs. These computer programs are used for analyzing the mooring, but the setting-up of the initial mooring configuration and the subsequent modifications on the basis of the results of the analysis are carried out by the design engineer.An expert system for mooring design is developed to eliminate the human expert from the design process and thus to enable a novice to design a mooring by himself. Using the expert system, an optimum least-weight in air design can be developed in much less time than is usually required in conventional procedures. Perhaps the most significant advantage is that the system can serve as a vehicle for effective transfer of present day expertise for future applications.The system is developed and implemented on an IBM PC/AT. It has a user-friendly, interactive, menu-driven input procedure and a sophisticated output facility. The design process is totally automated and the requirement to consult a human expert is easily eliminated. The system has tremendous flexibility and a knowledge engineer can easily adapt it to the specific requirements of a particular user. The concept of machine learning is introduced by recording the failure data and using this information in the later decision-making processes. A CAD package, AUTOCAD, is used to generate the drawings and an interface is developed between the CAD package and the expert system so that the former is transparent to the user.  相似文献   
2.
The selection of landfill sites for municipal solid waste (MSW) disposal involves consideration of geological, hydrological and environmental parameters which exhibit large spatial variability. Therefore, it is necessary to define, to what extent the chosen sites are reliable such that the probability of environmental pollution and health risks to population is minimal. In the present study, groundwater vulnerability to contamination has been assessed using the standard DRASTIC method. The results showed that the study region has 9.45% of very less, 32.94% of less, 25.47% of moderate, 22.79% of high and 9.35% of very high vulnerable zones. The study also revealed that none of the landfills are located in safe zones. This suggests that it requires proper remedial measures to avoid environmental pollution. A landfill site selection process has been carried out using the Analytical Hierarchy Process integrated with Geographical Information System tools. The obtained results showed that only 3.59?km2 (0.08%) of the total area is suitable for landfills. The reliability analysis of the site suitability revealed that landfills are located at unreliable locations where the probability of risk to environmental pollution is high. The presented approach assists decision-makers in selecting reliable locations for the safe disposal of MSW.  相似文献   
3.
Precision agriculture often relies on high-resolution imagery to delineate the variability within a field. Airborne Environmental Research Observational Camera (AEROCam) was designed to meet the needs of agriculture producers, ranchers, and researchers, who require high-resolution imagery in a near real-time environment for rapid decision support. AEROCam was developed and operated through a unique collaboration between several departments at the University of North Dakota, including the Upper Midwest Aerospace Consortium (UMAC), the School of Engineering and Mines, and flight operations at the John D. Odegard School of Aerospace Sciences. AEROCam consists of a Redlake MS4100 area-scan multi-spectral digital camera that features a 1920 × 1080 CCD array (7.4-μm detector) with 8-bit quantization. When operated at ~2 km above ground level, multispectral images with four bands in the visible and near infrared have a ground sample distance of 1 m with a horizontal extent of just over 1.6 km. Depending on the applications, flying at different altitudes can adjust the spatial resolution from 0.25 to 2 m. Rigorous spectral and radiometric calibrations allow AEROCam to be used in a variety of applications, qualitative and quantitative. Equipped with an inertial measurement unit (IMU) system, the images acquired can be geo-referenced automatically and delivered to end users near real time through our Digital Northern Great Plains system (DNGP). The images are also available to zone mapping application for precision farming (ZoneMAP), an online decision support tool for creating management zones from remote sensing imagery and data from other sources. Operational since 2004, AEROCam has flown over 250 sorties and delivered over 150,000 images to the users in the Northern Great Plains region, resulting in numerous applications in precision agriculture and resource management.  相似文献   
4.
The organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 14C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540 14C yr B.P.) and the Late Holocene (<4000 14C yr B.P.). Pollen analyses confirm that the deposits are mostly derived from the mangrove vegetation. Peat accumulation during the period 40,000–28,000 14C yr B.P. can be correlated with the excess rainfall, 40–100% greater than modern values, of the Asian summer monsoon. The low occurrence of mangrove between 22,000 and 18,000 14C yr B.P. can be attributed to the prevailing aridity and/or reduced precipitation associated worldwide with Last Glacial Maximum, because exposure surfaces and ferruginous layers are commonly found in intervals representing this period. The high rainfall of 11,000–4000 14C yr B.P. is found to be the most significant as the mangrove reached an optimum growth around 11,000 14C yr B.P. but with periods of punctuated weaker monsoons. From the present and previous studies, it has been observed that after about 5000 or 4000 14C yr B.P., the monsoons became gradually reduced leading to drying up of many of the marginal marine mangrove ecosystems. A case study of Hadi profile provided an insight to the relevance of magnetic susceptibility (χ) to record the ecological shift in Late Holocene.  相似文献   
5.
The present paper focuses mainly on the assessment of groundwater availability in the Upper Agniar and Vellar basins. The remote sensing data was used to map the geomorphological units and structural pattern. The integration of geomorphology and structural pattern with geophysical and well inventory data reveals that shallow groundwater occurrence is controlled by geomorphological characteristics whereas at intermediate depth faults/fractures control the yield of groundwater. The study has also indicated that the eastern part of the basins is more favourable for groundwater development than the western part.  相似文献   
6.
This study investigates the abundance, modes of occurrence and origin of major and trace elements in the Jurassic Tazareh coal in the northern Iran. A total of 27 samples (coal, coaly shale and siltstones) were collected and analyzed for trace elements by neutron activation analysis (INAA) and for major elements by X-ray fluorescence. The abundance of these elements is discussed in relation to local geological conditions. The correlation between the various elements is demonstrated through scatter diagrams and the possible genetic associations are discussed. Most elements (Al, Si, Na, K, Fe, Mg, Ti, Ba, Cr and REE) are positively correlated with ash yields that are inorganically associated. Bromine displays statistically signiûcant negative correlations with ash yield. The Ca, Zn, Se, As and Co present mixed modes of occurrence in the coal and probably associate with organic fraction.  相似文献   
7.
The increasing demand for building materials has led to indiscriminate exploitation of clay-rich topsoil from wetlands including the paddy lands of Central Kerala in the southwestern coast of India. The problem is critical in areas adjoining the major developmental centers having low per capita land and natural resource availability. Loss of fertile topsoil, shrinkage of agricultural lands and consequent food security issues, erosion of naturally evolved nutrients, lowering of water table in wells adjacent to the mining sites, etc., are some of the major environmental issues arising from indiscriminate brick and tile clay mining. Although, brick and tile clay mining brings short-term economic benefits and employment opportunities to a section of people, the process in the long run creates severe damages to the environmental settings of the area. The present paper deals with a few aspects of brick and tile clay mining in the paddy lands of Central Kerala, especially around Kochi City, a fast developing urban-cum-industrial center in South India, which demands large quantities of building materials including bricks and tiles for construction of infrastructural facilities. It is estimated that 729,695 tons/year (ty?1) of brick and tile clays are extracted from the coastal lowlands of Central Kerala, spreading to the Chalakudy (135,975 ty?1), Periyar (483,820 ty?1) and Muvattupuzha (109,900 ty?1) river basins. The N, P and K loss through extraction of brick and tile clays amounts to 210 ty?1, 96 ty?1 and 9,352 ty?1, respectively. As nutrient loss is an irreversible process in human time scale, its implications on agricultural productivity is a matter of serious concern. The study warrants the need for a comprehensive policy with an aim to regulate the mining activities on an environment- friendly basis in the densely populated coasts of the world, in general, and the study area in particular.  相似文献   
8.
The stomachs of 32 individuals of seven cetacean species incidentally caught in gill net and purseseine fisheries along Mangalore and Chennai coasts (India) between 2004 and 2006 were examined. The whole stomach (fore-gut, mid-gut and hind-gut) was examined in all cases. Prey remains (666 prey items comprising six species of teleosts, one crustacean and one squid species) were found in the stomachs of eight individuals (the remaining 24 stomachs were found to be empty). All cetaceans were found to feed mostly on teleosts with wide range of trophic levels. Based on an index that included frequency of occurrence, percentage by number and by weight, the oil sardine Sardinella longiceps was the main prey in the sample. Cetaceans appear to favour both pelagic as well as demersal prey, possibly indicating surface and benthic feeding habits.  相似文献   
9.
A red rain phenomenon occurred in Kerala, India starting from 25th July 2001, in which the rainwater appeared coloured in various localized places that are spread over a few hundred kilometers in Kerala. Maximum cases were reported during the first 10 days and isolated cases were found to occur for about 2 months. The striking red colouration of the rainwater was found to be due to the suspension of microscopic red particles having the appearance of biological cells. These particles have no similarity with usual desert dust. An estimated minimum quantity of 50,000 kg of red particles has fallen from the sky through red rain. An analysis of this strange phenomenon further shows that the conventional atmospheric transport processes like dust storms etc. cannot explain this phenomenon. The electron microscopic study of the red particles shows fine cell structure indicating their biological cell like nature. EDAX analysis shows that the major elements present in these cell like particles are carbon and oxygen. Strangely, a test for DNA using Ethidium Bromide dye fluorescence technique indicates absence of DNA in these cells. In the context of a suspected link between a meteor airburst event and the red rain, the possibility for the extraterrestrial origin of these particles from cometary fragments is discussed.  相似文献   
10.
It is a well established fact that geomorphology of an area exercises a significant control on the groundwater occurrence and movement. In an operational remote sensing project carried out by the National Remote Sensing Agency, India, this relationship between geomorphology and groundwater, coupled with the ability of Landsat data to provide regional geomorphic information, has been utilised to arrive at broad groundwater potential zones.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号