空间数据库引擎(SDE)在地图资源数据库管理中的应用   总被引：1，自引：0，他引：1  

胡卫民  徐雪仁  郭建恩  黄翰榕 《国土资源遥感》2000,11(4):67-70

随着地图资源数据在各个领域深入广泛的应用,作为应用基础和前提的地图资源数据的管理显得尤其重要。本文介绍了利用ESRI公司的空间数据库引擎(SDE),实现地图资源数据库管理的方法。该方法改变了传统的文件管理方式,不仅提高了地图数据资源的安全性,而且能使地图数据便于管理和使用,同时实现了局域网内地图资源的共享。  相似文献   

胶州湾毛颚类生态学研究   总被引：4，自引：0，他引：4  

王倩  孙松  霍元子  杨波 《海洋与湖沼》2010,41(4):639-644

根据2006年9月—2007年8月胶州湾浅水Ⅰ型浮游生物网的调查资料,分析了胶州湾毛颚类的种类组成、数量分布、摄食、生物量、生产力情况。结果表明,本次调查共出现毛颚类3种:强壮箭虫(Sagitta crassa)、拿卡箭虫(Sagitta nagae)和百陶箭虫(Sagitta bedoti)。其中强壮箭虫全年出现,在数量上占有绝对优势,年平均密度达到45.3ind/m3;拿卡箭虫和百陶箭虫在秋、冬、春季出现,年平均密度分别为0.17ind/m3和0.35ind/m3。通过推算得到胶州湾毛颚类年平均生物量为107.92mg/m2,年平均生产力为1.47mgC/(m2·d),占浮游动物总生产力的11.6%。毛颚类对浮游动物生物量和生产力的摄食压力在冬季达到全年最大值,分别为5.71%和83.47%,在春季、夏季、秋季毛颚类对浮游动物生物量的摄食压力分别为0.67%、0.08%、6.48%,对生产力的摄食压力分别为27.00%、2.48%和48.88%。由此可见,在冬季毛颚类的摄食对浮游动物群落结构等可能会产生重要影响。  相似文献   

Crew members in South Africa's squid industry; whether they have benefitted from transformation and governance reforms     

Mafaniso Hara 《Marine Policy》2009

Although crew members form bedrock of the squid industry, they have not benefitted from the transformation and governance reforms because: the harvesting technique necessitates incentivisation of individual effort; they are highly mobile; and the industry is exempted from revised labour legislation. As a result, they have been unable to organise for laying claim on benefits. As they unionise to strengthen their bargaining position, the conundrum is how to maintain incentive practices on which the catching sector is based while asserting their rights. The challenge is re-structuring the sector to improve quality of employment while maintaining individual crew member productivity incentives.  相似文献   

Comparison of the response of Atlantic cod (Gadus morhua) in the high-latitude regions of the North Atlantic during the warm periods of the 1920s–1960s and the 1990s–2000s     

Ken Drinkwater   《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):2087

Concern about future anthropogenic warming has lead to demands for information on what might happen to fish and fisheries under various climate-change scenarios. One suggestion has been to use past events as a proxy for what will happen in the future. In this paper a comparison between the responses of Atlantic cod (Gadus morhua) to two major warm periods in the North Atlantic during the 20th century is carried out to determine how reliable the past might be as a predictor of the future. The first warm period began during the 1920s, remained relatively warm through the 1960s, and was limited primarily to the northern regions (>60°N). The second warm period, which again covered the northern regions but also extended farther south (30°N), began in the 1990s and has continued into the present century. During the earlier warm period, the most northern of the cod stocks (West Greenland, Icelandic, and Northeast Arctic cod in the Barents Sea) increased in abundance, individual growth was high, recruitment was strong, and their distribution spread northward. Available plankton data suggest that these cod responses were driven by bottom-up processes. Fishing pressure increased during this period of high cod abundance and the northern cod stocks began to decline, as early as the 1950s in the Barents Sea but during the 1960s elsewhere. Individual growth declined as temperatures cooled and the cod distributions retracted southward. During the warming in the 1990s, the spawning stock biomass of cod in the Barents Sea again increased, recruitment rose, and the stock spread northward, but the individual growth did not improve significantly. Cod off West Greenland also have shown signs of improving recruitment and increasing biomass, albeit they are still very low in comparison to the earlier warming period. The abundance of Icelandic cod, on the other hand, has remained low through the recent warm period and spawning stock biomass and total biomass are at levels near the lowest on record. The different responses of cod to the two warm events, in particular the reduced cod production during the recent warm period, are attributed to the effects of intense fishing pressure and possibly related ecosystem changes. The implications of the results of the comparisons on the development of cod scenarios under future climate change are addressed.  相似文献   

Regression and Time Series Analysis of the World Oil Peak of Production: Another Look     

Peter Caithamer 《Mathematical Geosciences》2008,40(6):653-670

This paper analyzes world oil production data as a population/resource growth model. Both US and world oil production data are analyzed in terms of the logistic growth curve. It is shown that the logistic growth curve, while a suitable model for the American data, is not a suitable model for world oil production. A flexible family of curves which allows a wide range growth rates is considered. Using a nonlinear regression, one can predict various peak dates and total recoverable resources using different curves which all fit the data indistinguishably well.  相似文献   

Emerald deposits and occurrences: A review   总被引：3，自引：0，他引：3  

L.A. Groat  G. Giuliani  D.D. Marshall  D. Turner 《Ore Geology Reviews》2008,34(1-2):87

Emerald, the green gem variety of beryl, is the third most valuable gemstone (after diamond and ruby). Although it is difficult to obtain accurate statistics, Colombia supplies most (an estimated 60%, worth more than $500,000,000 per year) of the world's emeralds. However there is speculation that the emerald mines in Colombia are becoming depleted. Brazil currently accounts for approximately 10% of world emerald production. Emeralds have also been mined in Afghanistan, Australia, Austria, Bulgaria, China, India, Madagascar, Namibia, Nigeria, Pakistan, South Africa, Spain, Tanzania, the United States, and Zimbabwe.Because it is difficult to obtain accurate analyses of beryllium, most published analyses of beryl are renormalized on the basis of 18 oxygen and 3 Be atoms per formula unit. The color of emerald is due to trace amounts of chromium and/or vanadium replacing aluminum at the Y site; in most cases the Cr content is much greater than that of V. To achieve charge balance, the substitution of divalent cations at the Y site is coupled with the substitution of a monovalent cation for a vacancy at a channel site.Beryl is relatively rare because there is very little Be in the upper continental crust. Unusual geologic and geochemical conditions are required for Be and Cr and/or V to meet. In the classic model, Be-bearing pegmatites interact with Cr-bearing ultramafic or mafic rocks. However in the Colombian deposits there is no evidence of magmatic activity and it has been demonstrated that circulation processes within the host black shales were sufficient to form emerald. In addition, researchers are recognizing that regional metamorphism and tectonometamorphic processes such as shear zone formation may play a significant role in certain emerald deposits.A number of genetic classification schemes have been proposed for emerald deposits. Most are ambiguous when it comes to understanding the mechanisms and conditions that lead to the formation of an emerald deposit. Studies of individual emerald deposits show that in most cases a combination of mechanisms (magmatic, hydrothermal, and metamorphic) were needed to bring Be into contact with the chromophores. This suggests the need for a more flexible classification scheme based on mode of formation. Stable isotopes can be used to estimate the contribution of each mechanism in the formation of a particular deposit. Such estimates could perhaps be more precisely defined using trace element data, which should reflect the mode of formation.Emerald may be identified in the field by color, hardness, and form. It will tend to show up in stream sediment samples but because its specific gravity is relatively low, it will not concentrate in the heavy mineral fraction. In Colombia, structural geology, the sodium content of stream sediment samples, and the lithium, sodium, and lead contents of soil samples have all been used to find emerald occurrences. Exploration for gem beryl could result in the discovery of new occurrences of non-gem beryl or other Be minerals that could become new sources of Be and Be oxide.Future efforts should go towards creating a comprehensive data base of emerald compositions (including trace elements), determination of the role of metamorphism in the formation of some emerald deposits, improved classification schemes, and more effective exploration guidelines.  相似文献   

桂林市区域人粮关系及其协调研究   总被引：2，自引：1，他引：2  

周生路  朱凤武  彭补拙  赵其国 《地理科学》2000,20(1):78-82

采用粮食趋势产量与资源潜力产量结合、从食物消费结构探求粮食消费数量等方法，对桂林市未来区域人粮关系及其协调对策进行了研究。结果表明，未来该市人粮关系矛盾依然严峻，并有加重趋势；但在加大投入、提高粮食单产，加强计划生育、严格控制人口增长、大力开发周边旅游资源、分流外来游客、充分利用草山草坡资源、走“节粮”型畜禽 道路等前提下，人粮关系矛盾有望得到解决。  相似文献   

Lipid,sterol and saccharide sources and dynamics in surface soils during an annual cycle in a temperate climate region     

《Applied Geochemistry》2016

Multi-biomarkers were characterized in surface soils with different vegetation during an annual cycle in Oregon, U.S.A., to study the composition and dynamics of soil organic matter (SOM). The major compound classes identified include saccharides, steroids, terpenoids, and homologous series of aliphatic lipids (n-alkanoic acids, n-alkanols, and n-alkanes). Saccharides, n-alkanoic acids, and sterols were the most dominant compound groups identified in Ryegrass field soils, whereas n-alkanoic acids, n-alkanols, and sterols were dominant in soils under conifer and deciduous vegetation. Plant species, instead of microbial organisms, was found to be the primary source influencing the concentration and distribution of the major biomarker tracers in the studied surface soils. Over an annual cycle, concentrations of higher plant lipids such as monoacyl glycerides, sterols, n-alkanoic acids and total wax were higher during summer (especially June–August). During fall into winter, the concentrations of all compounds decreased to steady state levels due to cessation of de novo synthesis and concomitant biodegradation and remineralization of detritus. Sucrose and glucose reached maximum concentrations during spring (especially March–May), which could be related with plant growth, especially rootlets in the soils. Mycose, the microbial/fungal metabolite, maximized during late summer, suggesting the concomitant increase of microbial/fungal activity with the increasing primary production. The composition and variation of biomarkers observed over an annual cycle improved our understanding of SOM dynamics in temperate soils, which could also be linked to regional and global carbon cycles.  相似文献   

Coupled analysis of floating production systems     

D.L. Garrett   《Ocean Engineering》2005,32(7):802-816

Fully coupled global analysis of Floating Production Systems, including the vessel, the mooring system and the riser system is described. Design of the system can be a daunting task, involving more than 1000 load cases for global analysis. The primary driver for the mooring system and for the riser system is motion of the vessel. Vessel motions are driven by environmental forces, but are restrained by forces from the mooring and riser systems. Numerical models and procedures that provide accurate and efficient global modeling of the Floating Production System are presented. Both Time Domain and Frequency Domain procedures are included. The accuracy and efficiency of the procedures are illustrated in an example: a large semi with 16 mooring lines and 20 risers. The procedures provide the accuracy and efficiency for use of fully coupled analysis in design of Floating Production Systems from concept selection to final design, installation and operation.  相似文献   

Variations in the abundance of fisheries resources and ecosystem structure in the Japan/East Sea   总被引：1，自引：0，他引：1  

Chang Ik Zhang  Jae Bong Lee  Young Il Seo  Sang Cheol Yoon  Suam Kim 《Progress in Oceanography》2004,61(2-4):245

Evidence supports the hypothesis that two climatic regime shifts in the North Pacific and the Japan/East Sea, have affected the dynamics of the marine ecosystem and fisheries resources from 1960 to 2000. Changes in both mixed layer depth (MLD) and primary production were detected in the Japan/East Sea after 1976. The 1976 regime shift appears to have caused the biomass replacement with changes in catch production of major exploited fisheries resources, including Pacific saury, Pacific sardine and filefish. Both fisheries yield and fish distribution are reflected in these decadal fluctuations. In the 1960s and 1990s, common squid dominated the catches whereas in the 1970s and 1980s, it was replaced by walleye pollock. In the post-1988 regime shift, the distribution of horse mackerel shifted westward and southward and its distributional overlap with common mackerel decreased. The habitat of Pacific sardine also shifted away from mackerel habitats during this period. To evaluate changes in the organization and structure of the ecosystem in the Japan/East Sea, a mass-balanced model, Ecopath, was employed. Based on two mass-balanced models, representing before (1970–75) and after (1978–84) the 1976 regime shift, the weighted mean trophic level of catch increased from 3.09 before to 3.28 after. Total biomass of species groups in the Japan/East Sea ecosystem increased by 15% and total catch production increased by 48% due to the 1976 regime shift. The largest changes occurred at mid-trophic levels, occupied by fishes and cephalopods. The dominant predatory species shifted from cephalopods to walleye pollock due to the 1976 regime shift. It is concluded that the climatic regime shifts caused changes in the structure of the ecosystem and the roles of major species, as well as, large variations in biomass and production of fisheries resources.  相似文献