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Zonal Coupling Analysis Method of Seismic Response of Offshore Monopile Wind Turbine
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作者 XU Xiaofeng CHEN Shaolin SUN Jie 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第S01期103-110,共8页
The seismic safety of offshore wind turbines is an important issue that needs to be solved urgently.Based on a unified computing framework,this paper develops a set of seawater-seabed-wind turbine zoning coupling anal... The seismic safety of offshore wind turbines is an important issue that needs to be solved urgently.Based on a unified computing framework,this paper develops a set of seawater-seabed-wind turbine zoning coupling analysis methods.A 5 MW wind turbine and a site analysis model are established,and a seismic wave is selected to analyze the changes in the seismic response of offshore monopile wind turbines under the change of seawater depth,seabed wave velocity and seismic wave incidence angle.The analysis results show that when the seawater increases to a certain depth,the seismic response of the wind turbine increases.The shear wave velocity of the seabed affects the bending moment and displacement at the bottom of the tower.When the angle of incidence increases,the vertical displacement and the acceleration of the top of the tower increase in varying degrees. 展开更多
关键词 offshore monopile wind turbine seismic response analysis soil-junction interactions fluid-structure inter-action
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Gas sand distribution prediction by prestack elastic inversion based on rock physics modeling and analysis 被引量:5
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作者 贺芙邦 游俊 陈开远 《Applied Geophysics》 SCIE CSCD 2011年第3期197-205,240,共10页
Seismic inversion is one of the most widely used technologies for reservoir prediction. Many good results have been obtained but sometimes it fails to differentiate the lithologies and identify the fluids. However, se... Seismic inversion is one of the most widely used technologies for reservoir prediction. Many good results have been obtained but sometimes it fails to differentiate the lithologies and identify the fluids. However, seismic prestack elastic inversion based on rock physics modeling and analysis introduced in this paper is a significant method that can help seismic inversion and interpretation reach a new quantitative (or semi-quantitative) level from traditional qualitative interpretation. By doing rock physics modeling and forward perturbation analysis, we can quantitatively analyze the essential relationships between rock properties and seismic responses and try to find the sensitive elastic properties to the lithology, porosity, fluid type, and reservoir saturation. Finally, standard rock physics templates (RPT) can be built for specific reservoirs to guide seismic inversion interpretation results for reservoir characterization and fluids identification purpose. The gas sand distribution results of the case study in this paper proves that this method has unparalleled advantages over traditional post-stack methods, by which we can perform reservoir characterization and seismic data interpretation more quantitatively and efficiently. 展开更多
关键词 Rock physics seismic response elastic parameters elastic inversion reservoir characterization MODELING
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A Summary of Studies on Prediction of Urban Construction Land Scale 被引量:1
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作者 陈笑筑 王誉霖 徐龙 《Agricultural Science & Technology》 CAS 2017年第9期1744-1750,共7页
Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their char... Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their characteristics and deficiencies of these studies were analyzed to provide reference for deep research on pre- diction of urban construction land scale in China. The results show that there are few studies on basic theories about total scale of construction land presently, and there is no theoretical framework in studies on influencing factors. A single model has been used to conduct prediction on a small scale in most studies, but there have been few studies on iarge-scale prediction based on comprehensive benefit. Therefore, it is necessary to strengthen the exploration of basic theory and mechanism of urban construction land prediction, study iarge-scale prediction based on comprehensive benefit, and strengthen the comprehensive application of econometric analysis, spatial analysis and information technology analysis. 展开更多
关键词 Urban construction land Influencing factors Prediction models
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The analysis of frequency-dependent characteristics for fluid detection: a physical model experiment 被引量:2
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作者 陈双全 李向阳 王尚旭 《Applied Geophysics》 SCIE CSCD 2012年第2期195-206,235,236,共14页
According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a hi... According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a high-frequency bright spot as the amplitude energy shifts. However, it is a low-frequency shadow for the Class III AVO reservoirs saturated with hydrocarbons. In this paper, we verified the high-frequency bright spot results of Chapman for the Class I AVO response using the frequency-dependent analysis of a physical model dataset. The physical model is designed as inter-bedded thin sand and shale based on real field geology parameters. We observed two datasets using fixed offset and 2D geometry with different fluid- saturated conditions. Spectral and time-frequency analyses methods are applied to the seismic datasets to describe the response characteristics for gas-, water-, and oil-saturation. The results of physical model dataset processing and analysis indicate that reflection wave tuning and fluid-related dispersion are the main seismic response characteristic mechanisms. Additionally, the gas saturation model can be distinguished from water and oil saturation for Class I AVO utilizing the frequency-dependent abnormal characteristic. The frequency-dependent characteristic analysis of the physical model dataset verified the different spectral response characteristics corresponding to the different fluid-saturated models. Therefore, by careful analysis of real field seismic data, we can obtain the abnormal spectral characteristics induced by the fluid variation and implement fluid detection using seismic data directly. 展开更多
关键词 Frequency-dependent characteristic fluid detection time-frequency analysis attenuation and dispersion physical model
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“得”字与两种“得”字句 被引量:1
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作者 蒋雪梅 《成都师范学院学报》 1994年第4期38-45,共8页
关键词 “得”字句 语义关系 飒飒地响 兼语式 语意内容 句子 《新著国语文法》 句式转换 句法结构关系 敦煌变文
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Spatial and temporal variations of soil moisture in three types of agroforestry boundaries in the Loess Plateau, China 被引量:3
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作者 尤文忠 曾德慧 +3 位作者 刘明国 云丽丽 叶彦辉 张永 《Journal of Forestry Research》 SCIE CAS CSCD 2010年第4期415-422,521,共9页
Agroforestry is a ubiquitous landscape on the slopes in Loess Plateau, where soil moisture is a limiting factor for plant growth and development. The spatial and temporal characteristics of soil moisture were studied ... Agroforestry is a ubiquitous landscape on the slopes in Loess Plateau, where soil moisture is a limiting factor for plant growth and development. The spatial and temporal characteristics of soil moisture were studied in three types of agroforestry boundaries: forest-grassland, forest-cropland and shelterbelt-cropland. The result shows that soil moisture content decreased with soil depth increasing from the surface to 110 cm. Soil moisture content differed significantly among the three boundaries all in the rainy season (July-September), dry season (May-June) and spring (March-April). The horizontal distribution of soil moisture in different soil layers in the three types of boundaries showed different patterns with line form, wave form, scoop form or "W" form. The distance of edge influence (DEI) of soil moisture in different types of landscape boundaries was estimated by variance analysis and multiple comparisons. In dry season the DEI in 0-10 cm soil layer was 0.4 H (H, average height of trees), which ranged from 0.2 H in grassland or in cropland to 0.2 H in forest field for both forest-grassland and forest-cropland boundaries, and 0.7 H (ranged from 0.2 H in cropland to 0.5 H in forest field) for shelterbelt-cropland boundary. In rainy season the DEI at soil depth of 0-110 cm was 0.7 H for the three boundaries. The results indicated that agroforestry type should be carefully selected to maintain soil moisture in land management, especially in restoring degraded land in Loess Plateau. 展开更多
关键词 distance of edge influence forest-grassland system land use soil moisture
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Temporal-spatial Changes in Inner Mongolian Grassland Degradation during Past Three Decades 被引量:10
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作者 张清雨 吴绍洪 +1 位作者 赵东升 戴尔阜 《Agricultural Science & Technology》 CAS 2013年第4期676-683,共8页
[Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by lan... [Objective] This study aimed to analyze the temporal-spatial variation of Inner Mongolian grassland degradation during past three decades. [Method] The dis- tribution characteristics of grassland were described by land use types supervised classification with TM/ETM. Then, temporal-spatial changes of grassland coverage were quantified by the mean of maximum vegetation coverage in last 30 years. Lastly, the grassland degradation reasons were explored through statistic analysis between the grassland coverage and precipitation, temperature and grazing intensity. [Result] The grassland degradation index of Inner Mongolia was increased from 1.38 to 1.68, and the smallest was 1.28 in 2005s. Grassland degradation and improve- ment were concurrent after 1980s, but grassland degradation was the major change trend for Inner Mongolia grassland. The area of grassland degradation was enlarged from 18.08×10^4 km2 in 1980s to 22.47×10^4 km2 in 2010s on the whole and distribu- tion range was shifted from central-eastern to west in Inner Mongolia that mainly distributed on Hulun Buir and Xilin Gol grassland in 1980s and Ordos and Alax grassland in 2010s. The grassland area of degradation had a rising trend form 1980s to 1995s, then reduced to 10.8x104 km2 in 2005s, and decreased in 2010s, which mainly speared in the west of Xilin Gol grassland. [Conclusion] Inner Mongo-lian grassland degradation were become more seriously in last 30 years because that temperature, precipitation and graze intensities change, which not performance on decreasing coverage but grassland areas. 展开更多
关键词 Grassland degradation Temporal-spatial change Influencing factor Inner Mongolia
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A Numerical Study on the Effects of Orography During the Landfall Process of Typhoon Haitang 被引量:1
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作者 张建海 陈红梅 诸晓明 《Marine Science Bulletin》 CAS 2007年第1期3-12,共10页
The landfall process of typhoon Haitang which affected East China seriously was simulated by using the MM5 model and the track, intensity, precipitation and structure of typhoon were successfully reproduced. Then thro... The landfall process of typhoon Haitang which affected East China seriously was simulated by using the MM5 model and the track, intensity, precipitation and structure of typhoon were successfully reproduced. Then through the sensitive test, the effects of terrain were analyzed Results show that the irregular track during the period of typhoon passing through Taiwan and later landfalling at Fujian was in relation to the occurring and developing of orthographic impressed depression. The amount of rainfall was enhanced more than one time and the strength of typhoon was weakened 4 to 5 hPa. It is found that the effect of terrain on the structure of typhoon is limited at low level and is backward in space compared with the one at high level. In addition, the phenomenon that the equivalent temperature in the typhoon's moving direction inclines to the west on the eye of landfall may be concerned with the terrain. 展开更多
关键词 Typhoon Haitang orographic effects numerical experiments structural change
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Impacts and Countermeasures of Climate Change on Animal Husbandry in Qinghai Plateau and Its Surrounding Area 被引量:8
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作者 李红梅 李林 +1 位作者 邓振镛 黎明 《Agricultural Science & Technology》 CAS 2010年第7期138-144,共7页
The paper aims to study the impacts and countermeasures of climate change on animal husbandry in Qinghai plateau and its surrounding area,and evaluate the effect of countermeasures.Results showed that:First,the annua... The paper aims to study the impacts and countermeasures of climate change on animal husbandry in Qinghai plateau and its surrounding area,and evaluate the effect of countermeasures.Results showed that:First,the annual mean temperature,annual mean maximum temperature and annual mean minimum temperature showed an increasing trend in Qinghai plateau during the time from 1961 to 2008; the annual precipitation had not obvious change,but the obvious feature of seasonal change; wind speed and sunshine hours showed a decreasing trend during the time from 1961 to 2008.Secondly,under the current climate condition,grassland productivity showed a decreasing trend,and the grassland theoretical capacity affected by grassland productivity decreased too; warm winter was in favor of livestock overwintering safely,which resulted in a high level of the survival rate of young stock; temperature increasing and precipitation decreasing were beneficial to the fatness of livestock,but the meat yield of livestock was affected by some negative factors such as grassland degradation; livestock diseases had a close relationship with weather condition,and adverse weather condition may arose many diseases of livestock.Thirdly,in view of the current problems of livestock production,we took a series of countermeasures including grass industry construction,livestock improvement,developing new modes of animal husbandry,control and prevention of stockbreeding diseases and insect pests and recovery of meteorological disasters,which played a important role in promoting grassland productivity,solving the problem of the imbalances between livestock and forage,protecting the ecological environment and improving livestock performance. 展开更多
关键词 Climate change Qinghai plateau and its surrounding area Animal Husbandry Impact COUNTERMEASURES
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“文学女士”张洁
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作者 张林军 《语文世界(中旬刊)》 2003年第11期11-13,共3页
张洁以炽热的才情登上文坛,她的创作标志着女性写作的一个高度。2002年的《无字》三部曲,使她完成了由“情者”到“智者”的涅槃;在描写个人情感经历的同时,深入透视世道人心,笔力凝重,意味幽深。以前呼吁“爱是不能忘记的”,现在叹息... 张洁以炽热的才情登上文坛,她的创作标志着女性写作的一个高度。2002年的《无字》三部曲,使她完成了由“情者”到“智者”的涅槃;在描写个人情感经历的同时,深入透视世道人心,笔力凝重,意味幽深。以前呼吁“爱是不能忘记的”,现在叹息“爱是难以言说的”,情感表现的前后变异传达了她审美意趣的深化与老到,她历久不衰的文学力量,奠定了她在当代文坛的重要地位。这是“2002年度中华文学人物”评选委员会对获得首届“文学女士”称号的作家张洁所做的评语。今天就让我们走进“文学女士”张洁的作品,感受她的才情。 主持人:张林军(北京师范大学) 展开更多
关键词 文学人物 北京师范大学 女性写作 飒飒地响 《无字》 张洁 超级链接 麦穗 审美意趣 脸上的皱纹
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Influential Factors of House-purchasing Intention in Work construction Sites among Migrant Workers with a Case of Investigations on 203 Migrant Workers from Jiangxi Province 被引量:2
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作者 刘文 王彦之 《Agricultural Science & Technology》 CAS 2015年第12期2881-2885,共5页
The research selected 13 factors from individual and family characters, construction site characters and work characters and analyzed the influences on the willingness of purchasing houses on construction sites with L... The research selected 13 factors from individual and family characters, construction site characters and work characters and analyzed the influences on the willingness of purchasing houses on construction sites with Logistic regression mod- el. The results showed that gender, age differences, personality, willingness on fami- ly land conversion, management of enterprises on construction sites, relatives and friends on construction lands, and Job satisfaction were approved by significant testing, but marital status, annual household income, the rate of migrant worker in a household, transportation in work city, and corporate reputation were not approved by significant testing. 展开更多
关键词 Migrant worker House-purchasing willingness in work construction sites Influential factors Logistic regression analysis Jiangxi Province
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Dynamics of Slope Runoff and Soil Erosion of Different Forest Types in Karst Depression 被引量:6
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作者 张喜 连宾 +2 位作者 尹洁 吴永波 崔迎春 《Agricultural Science & Technology》 CAS 2010年第3期166-171,共6页
[Objective] The research was aimed to study the dynamics of slope runoff and soil erosion in different forest types in karst depression.[Method] Precipitation observation sites at the bottom of karst depression and ru... [Objective] The research was aimed to study the dynamics of slope runoff and soil erosion in different forest types in karst depression.[Method] Precipitation observation sites at the bottom of karst depression and runoff observation sites in different forest types were established to monitor regularly the main indices changes of runoff and soil erosion at fixed position in 4 years.[Result] The surface runoff of different forest types appeared singer peak from February to November,with lowest valley from June to July.The runoff coefficient appeared double peaks from February to May and from July to September.The changing coefficient of runoff appeared three peaks from March to April,from July to August and from September to November.The silt concentration appeared one peak from March to May and The erosion modulus appeared double peaks from March to May and from June to August.Runoff showed annually reduced trend with the growth of forests and the development of vegetation layer's structure.There was a positive correlation between the runoff and its silt concentration in different forest types.Precipitation and evaporation had notable positive correlation with the runoff,and similar correlation but not marked with silt concentration.The fitting analysis results of surface runoff and erosion modulus showed that rocky desertification intensified the unevenness of surface runoff and increased the surface runoff and erosion modulus.The penetrability of surface soil in new planted forest was lower than that in young forest,and that in surface soil of different forest types was higher than in bottom soil.[Conclusion] The research provided theoretical basis for the biological management technologies of water and soil conservation and the control of karst rocky desertification in karst regions. 展开更多
关键词 Karst depression Forest types RUNOFF Erosion modulus Affecting factors
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Differences of Photosynthetic Characteristics of the Grape Cultivated in Greenhouse and Open Field in Turpan 被引量:3
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作者 马微 牛莹莹 +3 位作者 骆强伟 孙峰 伍国红 廖康 《Agricultural Science & Technology》 CAS 2016年第6期1285-1288,1340,共5页
[Objective] This study compared the leaf photosynthetic characteristics of Turpan grape cultivated in greenhouses and open field to provide a scientific basis for the high-quality and high-yield cultivation of grape. ... [Objective] This study compared the leaf photosynthetic characteristics of Turpan grape cultivated in greenhouses and open field to provide a scientific basis for the high-quality and high-yield cultivation of grape. [Method] Two precocious grape varieties as experimental materials were cultivated in greenhouses and open field, and their net photosynthetic rates (Pn), photo-response curves and CO2 response curves were determined using Li-400XT portable photosynthesis system. [Result] The leaf Pn of the two varieties cultivated in open field was higher than that in greenhouse. The Pn of Hongqitezao cultivated in open field was the highest, up to 19.79 μmol/(m^2·s); in the photo-response curves, Hongqitezao cultivated in greenhouse had the largest Pnmax and apparent quantum yield (AQY), while the Flame Seedless in greenhouse had the smallest light compensation point (LCP). The light saturation point (LSP) value of greenhouse cultivation was higher than that of open field cultivation. In the CO2 response test, the dark respiration rate (Rd) and Pnmax of greenhouse cultivation were higher than those of open field cultivation, and the carboxylation efficiency (CE) of greenhouse cultivation was lower than that of open field cultivation; the CO2 compensation point (CCP) and CO2 saturation point (CSP) of greenhouse cultivation were lower than those of open field cultivation. [Conclusion] The utilization of elevated light in greenhouse cultivation was more efficient than in open field cultivation; however, the utilization of elevated CO2 in greenhouse cultivation was weaker than tin open field cultivation. 展开更多
关键词 Greenhouse cultivation Open field cultivation Photosynthetic characteristics Photo-response curve CO2 response curve
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Impact of Dry Warming on Economic and Characteristic Crop and Coping Technology in Northwest of China 被引量:4
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作者 邓振镛 倾继祖 +3 位作者 杨启国 宁惠芳 黄蕾诺 徐金强 《Agricultural Science & Technology》 CAS 2010年第4期124-129,共6页
Based on the state of characteristics of dry warming of modern climate changing,the response of growth,output and quality of main economic crops such as cotton,flax and winter rape and characteristic crop such as vini... Based on the state of characteristics of dry warming of modern climate changing,the response of growth,output and quality of main economic crops such as cotton,flax and winter rape and characteristic crop such as vinifera and apple were discussed.The coping technology for climate changing and measurements for serving the agricultural were provided. 展开更多
关键词 NORTHWEST Dry warming Economic crop Characteristic crop Influence Coping technology
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夏の砦(夏日城寨)
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作者 叶子 《东北亚外语研究》 1996年第2期58-59,共2页
夏の砦(夏日城寨)邦生作叶子译那是一年晚秋的事情,我们接连好几夜听到了擦过房顶又消失的不可思议的声音。一天夜里,我突然半夜醒来,听到象似河水不息地流过房顶似的飒飒响声。则耳聆听,这声音在房顶上响着,在庭院里响着,在我... 夏の砦(夏日城寨)邦生作叶子译那是一年晚秋的事情,我们接连好几夜听到了擦过房顶又消失的不可思议的声音。一天夜里,我突然半夜醒来,听到象似河水不息地流过房顶似的飒飒响声。则耳聆听,这声音在房顶上响着,在庭院里响着,在我家周围不断地飒飒地响着。是夜半而来... 展开更多
关键词 城寨 银杏叶 沙沙声 飒飒地响 沙沙作 进入梦乡 侯鸟 落叶层 可思议 银杏树
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Research on velocity and acceleration geophones and their acquired information 被引量:5
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作者 刘振东 吕庆田 +1 位作者 董世学 陈明春 《Applied Geophysics》 SCIE CSCD 2012年第2期149-158,234,共11页
Based on the research of two geophone types (10 Hz moving-coil velocity and piezoelectric acceleration) and their velocity and acceleration parameters, frequency response functions have been determined, as well as t... Based on the research of two geophone types (10 Hz moving-coil velocity and piezoelectric acceleration) and their velocity and acceleration parameters, frequency response functions have been determined, as well as the differences between them. Also, shock- vibration tests have been accomplished, not only to explain the two shock response signal differences, but also to analyze the response signal characteristics and its ability to carry information. In addition, seismic data acquisition experiments have been carried out under comparable conditions in the field. A contrast analysis of shot gathers and stack profiles acquired with the two geophone types is given in this paper. The results show that the acceleration signal from the acceleration geophone has a better advantage in terms of high signal-to-noise ratio, high accuracy, high resolution, and quantity of information to better meet current and future requirements for seismic exploration. 展开更多
关键词 seismic exploration GEOPHONE acceleration signal INTEGRITY ACCURACY
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Research on Regional Land Use Structure Change and Influencing Factors——A Case Study of Yining City in Xinjiang
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作者 刘志有 蒲春玲 +1 位作者 董嘉琪 赵晓洁 《Agricultural Science & Technology》 CAS 2012年第12期2655-2657,2662,共4页
This paper analyzes the land use status and land use structure change in 1995-2004 in Yining City, revealing that the agricultural land area has decreased rapidly, and construction land has increased dramatically. Mor... This paper analyzes the land use status and land use structure change in 1995-2004 in Yining City, revealing that the agricultural land area has decreased rapidly, and construction land has increased dramatically. Moreover, this paper inves- tigates the relation of economy, urbanization, location, land system policy with land use structure, and puts forward rationalization proposal for optimization of land use structure, to provide reference for land use measurements in the future. 展开更多
关键词 Land use structure Yining City Influence factors
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Emission Characteristics of Soil Nitrous Oxide from Typical Greenhouse Vegetable Fields in North China
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作者 徐钰 刘兆辉 +5 位作者 魏建林 石璟 谭德水 王梅 李国生 江丽华 《Agricultural Science & Technology》 CAS 2017年第3期438-442,共5页
To make clear the emission characteristics of soil N20 from typical green- house vegetable fields in North China, an experiment was conducted in greenhouse tomato field in Shouguang city, Shandong province, China's ... To make clear the emission characteristics of soil N20 from typical green- house vegetable fields in North China, an experiment was conducted in greenhouse tomato field in Shouguang city, Shandong province, China's "Home of Vegetables". The N2O fluxes were observed in four experimental treatments, as follows: none N fertilizer (CK), single organic fertilizer (OM), conventional fertilization (FP) and opti- mized and reduced nitrogen fertilization (OPT), by a close chamber-gas chromato- graph method. The effects of different fertilization treatments on N2O emission and tomato yield were analyzed. The results showed that following the fertilization and ir- rigation, the pulsed emissions of N2O were measured. The N2O emission peak ap- peared after basal fertilizer application and irrigation and could be maintained for about 20 days. While the N2O emission peak caused by topdressing was smaller and last only 3-5 days. The statistical analysis showed that the N2O fluxes were affected by air temperature, soil temperature and WFPS at soil depth of 3 cm. The total contents of soil N2O fluxes had significant differences among experimental groups. The total content orderly was FP of 14. 77 kg/hm^2, OPT of 9. 73 kg/hm^2, OM of 6.84 kg/hm^2 and CK of 2.37 kg/hm^2. The N~:~ emission coefficient ranged from 0.83%-1.10%,which was close to or more than the recommended value (1.0%) by IPCC. Compared with the FP treatment, the tomato yield in OPT treatment, whose application rate of chemical N fertilizer decreased by about 60%, increased by 2.2%. Under the current management measures, the reasonable reduction on ap- plicaUon rate of organic manure and chemical nitrogen fertilizer could effectively re- duce the N=O emissions in greenhouse vegetable fields. 展开更多
关键词 Greenhouse vegetable field N2O emission characteristic Influencingfactor Emission coefficient Tomato yield
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Hybrid FEM-BEM for simulation of electromagnetic response
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作者 余海涛 《Journal of Southeast University(English Edition)》 EI CAS 2004年第3期303-308,共6页
A finite element method with boundary element method (FEM-BEM) is presented for computing electromagnetic induction. The features of an edge element method including the volume and surface edge element method are inve... A finite element method with boundary element method (FEM-BEM) is presented for computing electromagnetic induction. The features of an edge element method including the volume and surface edge element method are investigated in depth. Surface basis functions of edge elements to an arbitrary shape of target are derived according to the geometrical property of basis functions and applied to discretize the surface integral equation for 3-D general targets. The proposed model is presented to compute resonant frequencies and surface current of underground unexplored ordnance (UXO), and then the electromagnetic responses of single target with different frequencies and positions of sensor are simulated and results are validated by experiments. 展开更多
关键词 Boundary element method Electromagnetic field effects Finite element method GEOMETRY Integral equations Radial basis function networks
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Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method 被引量:3
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作者 孟庆鑫 胡祥云 +1 位作者 潘和平 周峰 《Applied Geophysics》 SCIE CSCD 2017年第1期175-186,192,共13页
We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular... We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets. 展开更多
关键词 Surface-hole transient electromagnetic method multicomponent response analysis transient electric field three-dimensional finite-difference time-domain method discrete image method
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