期刊文献+
共找到8,409篇文章
< 1 2 250 >
每页显示 20 50 100
Floristic Composition, Population Structure, and Recruitment Status of Plant Species: A Case Study of Farmer-Managed Natural Regeneration Practices in Arid and Semi-Arid Lands in Kenya
1
作者 Simon Kosgei Choge Samson Okoth Ojunga +4 位作者 Dub Isacko Dokata William Kimen Chepkirui Justus Musau Faith Milkah Muniale Ivan Kiplagat Kiptui 《Open Journal of Forestry》 2024年第2期141-154,共14页
The technique of Farmer Managed Natural Regeneration (FMNR) is being promoted as a cost-effective approach for restoring degraded arable dry lands. Its effectiveness has been observed in many countries across the glob... The technique of Farmer Managed Natural Regeneration (FMNR) is being promoted as a cost-effective approach for restoring degraded arable dry lands. Its effectiveness has been observed in many countries across the globe, where it is a traditional practice, and is now being encouraged across the African continent. This study aimed to evaluate the impact of FMNR on floristic Composition, Vegetation Structure, and Regeneration Status of woody Plant Species in the severely degraded Central Rift, Kenya. The study systematically assessed how FMNR influenced species composition, vegetation structure and regeneration status from two sample plots involved in FMNR practices. Transect lines and quadrats methods were utilized to collect data, specifically regarding the floristic composition, vegetation structure, and regeneration status of woody plant species. Quadrats and sub-quadrats of varying sizes (10 m by 10 m, 5 m by 5 m, and 1 m by 1 m) were nested along the transect lines for data collection. Furthermore, measurements of tree growth and development, including root collar diameter, diameter at breast height (D<sub>130</sub>) and heights within the study blocks, were taken. The data was then analyzed using R-software. Results showed a marked progressive increase in numbers of trees, saplings, seedlings, shrubs and herbs in all FMNR sites and reductions in all non-FMNR sites. The study advocates for widespread promotion of the FMNR practice both as an environmental conservation and restoration strategy. 展开更多
关键词 Farmer managed Natural Regeneration FMNR Floristic Composition Vegetation Structure REGENERATION BIODIVERSITY
下载PDF
Fungal diversity and community composition responses to the reintroduction of fire in a non-managed Mediterranean shrubland ecosystem
2
作者 Juncal Espinosa Tatek Dejene +3 位作者 Mercedes Guijarro Xim Cerdá Javier Madrigal Pablo Martín-Pinto 《Forest Ecosystems》 SCIE CSCD 2023年第2期268-278,共11页
Background:More than a decade of fire suppression has changed the structure of fire-adapted shrubland ecosystems in Spain’s National Parks,which are now at extreme risk of uncontrolled wildfires.Prescribed burning ca... Background:More than a decade of fire suppression has changed the structure of fire-adapted shrubland ecosystems in Spain’s National Parks,which are now at extreme risk of uncontrolled wildfires.Prescribed burning can mitigate the risk of wildfires by reducing the fuel load but prescribed burning may also alter the soil properties and reduce microbial and fungal activity,causing changes in the availability of nutrients deep in the soil layer.Although fungal communities are a vital part of post-fire restoration,some fire effects remain unclear.To examine the short-term effects of prescribed burning on soil fungal communities in Doñana Biological Reserve(SW Spain),we collected soil samples pre-burn and 1 day,6 and 12 months post-burn from burned plots to perform physicochemical and metabarcode DNA analyses.Results:Prescribed burning had no significant effect on the total fungal operational taxonomic unit richness and abundance.However,changes in soil pH,nitrogen and potassium content post-burn affected fungal community composition.Small non-significant changes in pH and phosphorous affected the composition of ectomycorrhizal fungi.Conclusions:The ectomycorrhizal fungal community appears to be resilient to the effects of low-to moderate-intensity fires and saprotrophic taxa may benefit from this kind of fire.This finding revealed that prescribed burning is a potentially valuable management tool for reducing fire hazards in shrublands that has little effect on the total richness and abundance of fungal communities. 展开更多
关键词 Doñana National Park Ectomycorrhizal fungi Fire ecology Forest management Global change Prescribed burning WILDFIRE Saprotrophic fungi
下载PDF
A dynamic managed pressure well-control method for rapid treatment of gas kick in deepwater managed pressure drilling 被引量:1
3
作者 Hong-Wei Yang Jun Li +4 位作者 Ji-Wei Jiang Hui Zhang Bo-Yun Guo Geng Zhang Wang Chen 《Petroleum Science》 SCIE CAS CSCD 2022年第5期2297-2313,共17页
During deepwater managed pressure drilling(MPD),the gas kick may occur in abnormally high-pressure formations.If the traditional well control method is adopted,the treatment time is long and the advantage of early gas... During deepwater managed pressure drilling(MPD),the gas kick may occur in abnormally high-pressure formations.If the traditional well control method is adopted,the treatment time is long and the advantage of early gas kick detection of MPD is lost.The dynamic managed pressure well-control(MPWC)method can be used to rapidly treat gas kick in deepwater MPD.In this paper,considering the effect of large-variable-diameter annulus and complex wellbore temperature in deepwater drilling,a simplified model of non-isothermal gas-liquid two-phase flow was established for dynamic deepwater MPWC simulation.Using this model,the response characteristics of outlet flow and wellhead backpressure were investigated.The results indicated that the gas fraction,outlet liquid flow rate,pit gain and wellhead backpressure presented complex alternating characteristics when gas moved upwards in the wellbore due to the large-variable-diameter annulus.The outlet liquid flow rate would be lower than the inlet flow rate and the pit gain would decrease before the gas moved to the wellhead.The variation trend of the wellhead backpressure was consistent with that of the pit gain.When the gas-liquid mixture passed through the choke,the expansion or compression of the gas caused part of the choke pressure drop to be supplemented or unloaded,delaying the response rate of the wellhead backpressure.The wellbore temperature,borehole diameter and seawater depth had different effects on outlet flow rate,pit gain and wellhead backpressure.This research could provide a new idea for well control methods in deepwater managed pressure drilling. 展开更多
关键词 Gas kick managed pressure well-control Gas-liquid two-phase flow Wellhead backpressure Outlet flow characteristics Deepwater managed pressure drilling
下载PDF
基于Managed DirectX的三维建模器的开发与研究 被引量:1
4
作者 杨建鸣 王鹏飞 边明杰 《中国制造业信息化(学术版)》 2007年第6期45-47,共3页
针对目前.NET技术应用范围的不断扩大,通过.NET构架,充分利用.NET的快速开发能力,开发了基于Managed DirectX的三维建模器,作为下一步基于三维建模器的虚拟产品技术的基础和平台,在此系统的开发过程中研究了Managed DirectX的开发技术... 针对目前.NET技术应用范围的不断扩大,通过.NET构架,充分利用.NET的快速开发能力,开发了基于Managed DirectX的三维建模器,作为下一步基于三维建模器的虚拟产品技术的基础和平台,在此系统的开发过程中研究了Managed DirectX的开发技术及相关三维图形算法。 展开更多
关键词 managed DIRECTX .NET 三维建模器
下载PDF
Managed DirectX三维建模技术中的类实现
5
作者 邢静宜 王鹏飞 +1 位作者 谭小峰 顾瑞春 《计算机技术与发展》 2007年第4期208-210,共3页
三维建模技术是进行三维仿真的基础,使用高级语言和图形接口进行三维建模的开发是根本的解决方法。针对目前.NET技术的快速发展与应用,采用.NET语言和Managed DirectX技术进行开发,对基于Managed DirectX的三维建模技术中的三维模型类... 三维建模技术是进行三维仿真的基础,使用高级语言和图形接口进行三维建模的开发是根本的解决方法。针对目前.NET技术的快速发展与应用,采用.NET语言和Managed DirectX技术进行开发,对基于Managed DirectX的三维建模技术中的三维模型类进行了研究及实现,并在.NET环境下开发了三维模型基类库,其中使用了参数化建模方法。最终实现了基本的三维建模类,在此基础上可进一步开发出通用的三维建模器。Managed DirectX作为DirectX中重要的成员,为基于.NET框架开发三维图形应用程序提供了极大的方便。 展开更多
关键词 managed DIRECTX .NET 三维建模 类实现
下载PDF
Optimization purchase price and the profit policy undervendor managed inventory 被引量:3
6
作者 GuoHaifeng HuangXiaoyuan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第2期321-324,共4页
The optimization policy of the purchase price and the profit under vendor managed inventory(VMI) is studied. For a salable product, supply chain mode of VMI is established, which is based on deterministic demand, havi... The optimization policy of the purchase price and the profit under vendor managed inventory(VMI) is studied. For a salable product, supply chain mode of VMI is established, which is based on deterministic demand, having initial stock and having stock-out cost. With the further analysis of the mode, VMI is found to increase profits of the buyer in the short-term motivation. But VMI will reduce profits of the supplier under the matching condition. And in the short-term motivation, VMI will increase the purchase price to compensate the transfer cost of the supplier. As a result, the foundation of theory is provided to implement VMI in the supply chain, and have some definituded project significance. 展开更多
关键词 supply chain vendor managed inventory purchase price profit.
下载PDF
Coarse woody debris and wood-colonizing fungi differences between a reserve stand and a managed forest in the Taborz region of Poland 被引量:2
7
作者 Slwomir Pieeka Agata Sotnik +1 位作者 Marta Damszel Zbigniew Sierota 《Journal of Forestry Research》 SCIE CAS CSCD 2019年第3期1081-1091,共11页
The aim of this research was to evaluate the amount of woody debris (m3/ha) on the forest floor and the associated wood-colonizing fungi. The study was performed in the Taborz region, known for its Scots pine provenan... The aim of this research was to evaluate the amount of woody debris (m3/ha) on the forest floor and the associated wood-colonizing fungi. The study was performed in the Taborz region, known for its Scots pine provenance experiments, against the background of a recently launched Polish legislation to protect the biodiversity on the forest floor in managed (harvested) stands. We investigated a managed stand (136-years-old) and the reserve stand ‘Sosna Taborska’(261-years-old). In the reserve stand, the mean volume of woody debris was six times higher than in the managed forests, i.e. 65 versus 11 m3/ha. In addition, in the reserve stand, the number of fungi taxa colonizing the dead wood was larger than in the managed stands, with a higher number of fruitbodies. Total fungal richness was higher in the reserve than in the managed stand, i.e. 28 versus 12 species. The dominant taxa at both sites were Fomitopsis pinicola and Fomes The aim of this research was to evaluate the amount of woody debris (m^3/ha) on the forest floor and the associated wood-colonizing fungi. The study was performed in the Taborz region, known for its Scots pine provenance experiments, against the background of a recently launched Polish legislation to protect the biodiversity on the forest floor in managed (harvested) stands. We investigated a managed stand (136-years-old) and the reserve stand ‘Sosna Taborska’(261-years-old). In the reserve stand, the mean volume of woody debris was six times higher than in the managed forests, i.e. 65 versus 11 m^3/ha. In addition, in the reserve stand, the number of fungi taxa colonizing the dead wood was larger than in the managed stands, with a higher number of fruitbodies. Total fungal richness was higher in the reserve than in the managed stand, i.e. 28 versus 12 species. The dominant taxa at both sites were Fomitopsis pinicola and Fomes fomentarius, although some taxa were only found in the reserve (e.g., Stereum hirsutum). The volume of woody debris as well as the diversity of fungi in the managed stand were lower than in the reserve, albeit greater than in other Scots pine stands in Poland. These results testify to the gains in biodiversity yielded by the management conservation management approach at the reserve stand. 展开更多
关键词 Coarse WOODY DEBRIS FUNGI managed (harvested) STANDS RESERVE Sosna Taborska RESERVE FOREST Indices
下载PDF
Managed Pressure Drilling Technology,As the Lost Piece of the Drilling Puzzle,Results in More Economical Benefits 被引量:1
8
作者 Arash Shadravan 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期74-74,共1页
The economics of drilling wells is important as we drill deeper wells whether offshore or onshore. Drilling-related problems,including stuck pipe,lost circulation,and excessive mud cost,show the need for better drilli... The economics of drilling wells is important as we drill deeper wells whether offshore or onshore. Drilling-related problems,including stuck pipe,lost circulation,and excessive mud cost,show the need for better drilling technology.If we can solve these problems,the economics of drilling the wells will improve,thus enabling the industry to drill wells that were previously uneconomical.Managed pressure drilling techniques,at one time,having 展开更多
关键词 managed pressure DRILLING underba-lanced DRILLING DRILLING technologies ECONOMY
下载PDF
U. S. Academic Medical Centers Under the Managed Health Care Environment 被引量:1
9
作者 KRISTINA GUO (School of Policy and Managment, Florida International University,North Miami, FL 33181, U. S. A.) 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 1999年第2期81-87,共7页
This research investigates the impact of managed health care on academic medical centers in the United States. Academic medical centers hold a unique position in the U. S. health care system through their missions of ... This research investigates the impact of managed health care on academic medical centers in the United States. Academic medical centers hold a unique position in the U. S. health care system through their missions of conducting cutting-edge biomedical researeh, pursuing clinical and technological innovations, Providing state-of-the-art medical care and producing highly qUalified health professionals. However, policies to control costs through the use of managed care and limiting resources are detrimental to academic medical centers and impede the advancement of medical sciTo survive the threats of managed care in the health care environment, acadendc medical centers must rely on their upper level managers to derive successful strategies. The methods used in this study include qualitative approaches in the form of key informants and case studies. In addition, a survey questionnaire was sent to 1h8 CEOs in all the academic medical centers in the U. S. The findings revealed that managers who perform the liaison, monitor, entrepreneur and resource allocator roles are crucial to ensure the survival of academic medical centers, so that academic medical centers can continue their missions to serve the general public and promote their well-being. 展开更多
关键词 Academic Medical Centers Cost Control Health Policy Humans managed Care Programs Organizational Innovation United States
下载PDF
用MFC框架实现Managed C++、C#、VB.NET集成应用 被引量:1
10
作者 孙辉 《MSDN开发精选》 2005年第3期82-84,共3页
本文在详细讲述了组装好的全新的MFC应用程序之后。深入地讲解了各个零件之间的交互。如果将应用程序EE作一台机器。前面的文章介绍了零件的制造和组装。本文则介绍了零件之间的传动;这样。一台机器才得以运转。
关键词 MFC managed C++ C# VB语言 .NET 集成 应用程序 程序设计语言
下载PDF
Hydrological and economic feasibility of mitigating a stressed coastal aquifer using managed aquifer recharge: a case study of Jamma aquifer, Oman
11
作者 Mustafa EL-RAWY Ali AL-MAKTOUMI +2 位作者 Slim ZEKRI Osman ABDALLA Rashid AL-ABRI 《Journal of Arid Land》 SCIE CSCD 2019年第1期148-159,共12页
This study explored the hydrological and economic feasibility of managed aquifer recharge(MAR) using tertiary treated wastewater(TWW) to mitigate salinity in the coastal aquifer of Jamma, Oman. A steady-state groundwa... This study explored the hydrological and economic feasibility of managed aquifer recharge(MAR) using tertiary treated wastewater(TWW) to mitigate salinity in the coastal aquifer of Jamma, Oman. A steady-state groundwater flow and transport model, using MODFLOW software, was developed and calibrated. Different managerial scenarios were simulated and the results reveal that the Jamma aquifer will be further deteriorated in the next 20 a if it remains unmanaged. The groundwater table will decline further by more than 3 m on average; and the iso-concentration salinity line of 1500 mg/L will advance 2.7 km inland, which will severely affect the farming activities in the area. However, MAR using TWW when integrated with the management of groundwater abstraction(e.g., using modern irrigation systems to reduce the abstraction rate) becomes hydrologically feasible to augment the aquifer storage and control seawater intrusion, and hence improves the farming activities. The results indicate that:(1) injecting TWW in the vicinity of irrigation wells(Scenario A2);(2) investing in smart water meters and online control of pumping from the wells to reduce the abstraction rate by 25%(Scenario B); and(3) a combination of both(Scenario B2) are feasible scenarios with positive net present values. Recharge in upstream areas is found not economically feasible because of the very high investment cost of the installation of pipes to transport the TWW over a distance of 12.5 km. Because of securing funds are challenging, Scenario B would be the best option and the second-best option is Scenario A2. Scenario B2 has the lowest net benefit investment ratio and is very attractive because it entails integrated demand and supply management of groundwater. It is required to reduce pumping and to invest in injecting TWW to improve groundwater quality in the vicinity of irrigation wells and to form a hydrological barrier to control seawater intrusion in the long run. 展开更多
关键词 managed AQUIFER RECHARGE treated WASTEWATER SALINITY line COASTAL AQUIFER Oman
下载PDF
Effect of intervention and type of forest management on quality andquantity characteristics of dead wood in managed and reserve forests: Acase study
12
作者 Kambiz T. Abkenari Fateme Akbari Babak Pilehvar 《Journal of Forestry Research》 SCIE CAS CSCD 2012年第3期413-418,共6页
We compared the dead wood (DW) conditions of Chesh- meh-sar forest and Sardab forest with different management history, including reserve forest and harvested forest. The First forest took 100% inventory from all th... We compared the dead wood (DW) conditions of Chesh- meh-sar forest and Sardab forest with different management history, including reserve forest and harvested forest. The First forest took 100% inventory from all the available DW. Also dead trees were compared in terms of species, shape, location and quality of fracture in both forests. Volumes of dead wood in Cheshmeh-sar and Sardab forests were 207.47 and 142.74 m3, respectively. Due to this significant difference, impact on the management level was determined. In Cheshmeh-sar forest, 42% of dead trees were standing and 58% were fallen type while in Sardab forest 38.6% were standing and 61.4% fallen. But the difference was not statis- tically significant l^etween them (p = 0.0587). In terms of quality, dead trees of hard, soft and hollow had the highest frequency, respectively. However, 71.5% of DW was seen as hard dead in Cheshmeh-sar forest while hard dead trees in Sardab forests were 54.2%. Soft quality degree of dead trees which formed in Cheshmeh-sar and Sardab forest were calcu- lated as 26.6% and 43.4% respectively. Also 30% of the dead trees of Sardab forest were eradicated while in Cheshmeh-sar this amount was reduced to 12%. Due to this significant difference ((P=0/018), it is concluded that the type of management and human interference are affecting the quality of dead trees and makes us to think the human in- terferences could effect on the ecosystem of touched forests. 展开更多
关键词 dead wood intact forests managed forest reserve forest North of Iran
下载PDF
Managed Aquifer Recharge (MAR) through Surface Infiltration in the Azraq Basin / Jordan
13
作者 Marwan Alraggad Hind Jasem 《Journal of Water Resource and Protection》 2010年第12期1057-1070,共14页
Until the early 1990s the Azraq basin in Jordan was covered by a huge wetland in the central parts representing a source of fresh water for all purposes. The presence of such wetland in the desert created a natural pa... Until the early 1990s the Azraq basin in Jordan was covered by a huge wetland in the central parts representing a source of fresh water for all purposes. The presence of such wetland in the desert created a natural pathway for migratory birds. Man made and natural impacts caused severe depletion of this basin and the oasis disappeared in the early 1990s. Under a GIS environment MAR layers were prepared for the Azraq basin. MAR mapping showed a very high and high potentials over 20.55% and 61.63% of the total basin area respectively;while the low potential areas represent only 4.03% of the total area. 展开更多
关键词 Azraq BASIN Climate Change Integrated Water Resources Management managed AQUIFER RECHARGE
下载PDF
Potential Areas for Managed Aquifer Recharge in the Eastern Lower Jordan Valley Area
14
作者 Elias Salameh Ghaida Abdallat 《Journal of Water Resource and Protection》 2020年第4期330-357,共28页
The article deals with the feasibility of using the recent geological formations in the eastern Jordan Valley for water storage through artificial recharge due to water scarcity and water needs in this area. Water sto... The article deals with the feasibility of using the recent geological formations in the eastern Jordan Valley for water storage through artificial recharge due to water scarcity and water needs in this area. Water storage in surface reservoirs in arid and semi-arid areas is afflicted with a variety of issues such as high evaporation, eutrophication processes and exposure to contamination and accidents. Dams to capture all rare-event floods are, generally, big and expensive structures. Artificially recharging aquifers and storing the water in the underground offer a competing alternative. In this study, hydrogeological, geological, geophysical and hydrochemical investigations were carried out to study the potentials of the eastern side of the Lower Jordan Valley for artificial recharge. The results reveal that relatively extended areas on the eastern side of the Lower Jordan Valley have the potential to accommodate large amounts of recharge water and that the impacts of artificially storing the water in aquifers are to be judged very positive compared to surface storage, especially when the amounts of available recharge water can quantitatively be accommodated in recharge facilities. In addition, the study shows, the advantages of underground water storage compared to surface storage in dams. The potential storage capacities in the different parts of the Lower Jordan Valley are quantified based on rechargeable aquifer volumes and porosities. The potential uses of the recharged water are also elaborated on depending on recharge and aquifer water qualities. 展开更多
关键词 managed AQUIFER RECHARGE (MAR) JORDAN VALLEY POTENTIAL Storage Hydrogeological Conditions
下载PDF
Reducing Nitrogen Loss in Subsurface Tile Drainage Water with Managed Drainage and Polymer-Coated Urea in a River Bottom Soil
15
作者 Patrick R. Nash Kelly A. Nelson Peter P. Motavalli 《Journal of Water Resource and Protection》 2014年第11期988-997,共10页
Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not bee... Poorly-drained, river bottom soils can be high corn (Zea mays L.) yielding environments, but saturated soil conditions often reduce corn yields. Wabash soils located in river bottoms in Northeast Missouri have not been traditionally tile drained due to high clay content which requires narrow tile drain spacings. Increased land prices in the region have increased interest in tile draining poorly-drained bottom land soils to increase corn yields which could have a deleterious effect on water quality. The objectives of the three-year study were to determine whether use of managed subsurface drainage (MD) in combination with a controlled release N fertilizer could reduce the annual amount of NO3--N loss through tile drainage water compared to free subsurface drainage (FD) with a non-coated urea application. Annual NO3--N loss through tile drainage water with FD ranged from 28.3 to 90.1 kg·N·ha-1. Nitrogen fertilizer source did not affect NO3--N loss through tile drainage water, which was likely due to limited corn uptake over the three-year study due to adverse weather conditions. Averaged over three years, MD reduced tile water drained 52% and NO3--N loss 29% compared to FD. Reduction in NO3--N loss through tile drainage water with MD compared to FD was due to reduced tile flow during the non-cropping period. Annual flow-weighted mean concentration of NO3--N in the tile water was 5.8 mg·N·L-1 with FD and 8.1 mg·N·L-1 with MD. Tile draining river bottom soils at this location for continuous corn production may not pose a health risk over the evaluated duration. 展开更多
关键词 Free Drainage managed Drainage NITRATE Nitrogen Polymer-Coated UREA SUBSURFACE TILE Drainage
下载PDF
Managed aquifer recharge(MAR)applications in China–achievements and challenges
16
作者 Jin-xing Guo Zhi-ping Li Catalin Stefan 《Journal of Groundwater Science and Engineering》 2022年第1期57-69,共13页
Groundwater is of fundamental significance for human society,especially in semi-arid areas in China.However,due to the fast social and economic development,China has been suffering from the shortage of water resource.... Groundwater is of fundamental significance for human society,especially in semi-arid areas in China.However,due to the fast social and economic development,China has been suffering from the shortage of water resource.In this situation,managed aquifer recharge(MAR)was considered to be an effective measure for the sustainable management of groundwater resources.Since 1960 s,China successfully implemented many MAR schemes for different purposes such as restoration of groundwater tables,prevention of seawater intrusion,increasing urban water supplies and controlling land subsidence.From those successful experiences China developed a scientific and applicable system to implement MAR project.However,there were still many challenges in this field,for example,treated waste water had been barely used for recharge.The present review summarized the achievements in MAR applications in China as well as the associated challenges within the past 55 years before the year 2016. 展开更多
关键词 managed aquifer recharge(MAR) GROUNDWATER RECHARGE AQUIFER STORAGE
下载PDF
Remote Monitoring of Vegetation Managed for Dust Control on the Dry Owens Lakebed, California
17
作者 David P. Groeneveld David D. Barz 《Open Journal of Modern Hydrology》 2013年第4期253-268,共16页
A monitoring program was developed to assess the cover of saltgrass managed for dust control on the saline dry Owens Lake. Although the original intent was to manage the vegetation as total cover that included green a... A monitoring program was developed to assess the cover of saltgrass managed for dust control on the saline dry Owens Lake. Although the original intent was to manage the vegetation as total cover that included green and senesced leaf and stem material, aged leaves that make up a large proportion of total cover were not differentiable spectrally from the background salt and lakebed. Hence, greenness-based indices were explored for detection of plant recruitment. Since all plant cover begins as green and growing, greenness indices provide a measure of all future cover whether living or senesced. The criteria for judging compliance were changed so that spatially variable vegetation cover measured as a milestone will need to be met in the future. A derivative of NDVI, NDVIx, calculated using scene statistics, proved highly accurate, to about 0.001 of this index and with an average signal to noise ratio of 64. This high level of accuracy allowed detection of small changes in vegetation growth and vigor. Performance according to the benchmark-as-par standard was determined through combined use of cumulative distribution functions and derivative maps. 展开更多
关键词 DUST Control REMOTE Sensing Monitoring managed VEGETATION NDVI Owens LAKE California
下载PDF
The Potential Impact of Incentives on Managed Lane Travel
18
作者 Namoo A. Han Mark W. Burris 《Journal of Transportation Technologies》 2018年第4期255-272,共18页
The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lan... The use of managed lanes to control and maximize freeway throughput is increasing. One way of encouraging more managed lane use is through the implementation of incentives. In the Dallas-Fort Worth area, a managed lane is being added to the I-30 (Tom Landry freeway) and incentives to maximize the use of this lane were planned. Since the managed lanes were not yet open and the incentives were hypothetical, a stated preference survey was used to gauge the potential impact of the incentives on traveler behavior. The stated preference questions were designed using Db-efficient and random adaptive designs. The incentives were chosen by looking at other programs around the country and through discussion with transportation experts. Once ready, the survey was administered online to travelers in the area and a total of 898 usable responses were gathered. From the responses, a mixed-logit model was developed to describe and predict traveler behavior. From the model, elasticities were calculated to predict the impact of the incentives on mode choice. The model found that incentives with discounts and free trips (a transit fare discount, express bus service to downtown, a free trip for every X number of paid trips, and a discount offered to select businesses) were more effective at encouraging managed lane use. The other incentives (gift card worth $5 for every X number of trips and $5 in credit for every X number of trips taken by transit) had less of an impact. 展开更多
关键词 managed Lanes INCENTIVES Stated PREFERENCE SURVEY
下载PDF
National Forest Inventories capture the multifunctionality of managed forests in Germany 被引量:3
19
作者 Nadja K.Simons María R.Felipe-Lucia +26 位作者 Peter Schall Christian Ammer Jürgen Bauhus Nico Blüthgen Steffen Boch François Buscot Markus Fischer Kezia Goldmann Martin M.Gossner Falk Hänsel Kirsten Jung Peter Manning Thomas Nauss Yvonne Oelmann Rodica Pena Andrea Polle Swen C.Renner Michael Schloter Ingo Schöning Ernst-Detlef Schulze Emily F.Solly Elisabeth Sorkau Barbara Stempfhuber Tesfaye Wubet Jörg Müller Sebastian Seibold Wolfgang W.Weisser 《Forest Ecosystems》 SCIE CSCD 2021年第1期50-68,共19页
Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forest... Background:Forests perform various important ecosystem functions that contribute to ecosystem services.In many parts of the world,forest management has shifted from a focus on timber production to multi-purpose forestry,combining timber production with the supply of other forest ecosystem services.However,it is unclear which forest types provide which ecosystem services and to what extent forests primarily managed for timber already supply multiple ecosystem services.Based on a comprehensive dataset collected across 150 forest plots in three regions differing in management intensity and species composition,we develop models to predict the potential supply of 13 ecosystem services.We use those models to assess the level of multifunctionality of managed forests at the national level using national forest inventory data.Results:Looking at the potential supply of ecosystem services,we found trade-offs(e.g.between both bark beetle control or dung decomposition and both productivity or soil carbon stocks)as well as synergies(e.g.for temperature regulation,carbon storage and culturally interesting plants)across the 53 most dominant forest types in Germany.No single forest type provided all ecosystem services equally.Some ecosystem services showed comparable levels across forest types(e.g.decomposition or richness of saprotrophs),while others varied strongly,depending on forest structural attributes(e.g.phosphorous availability or cover of edible plants)or tree species composition(e.g.potential nitrification activity).Variability in potential supply of ecosystem services was only to a lesser extent driven by environmental conditions.However,the geographic variation in ecosystem function supply across Germany was closely linked with the distribution of main tree species.Conclusions:Our results show that forest multifunctionality is limited to subsets of ecosystem services.The importance of tree species composition highlights that a lack of multifunctionality at the stand level can be compensated by managing forests at the landscape level,when stands of complementary forest types are combined.These results imply that multi-purpose forestry should be based on a variety of forest types requiring coordinated planning across larger spatial scales. 展开更多
关键词 Ecosystem processes and services Forest management Structural diversity Tree species composition Trade-offs and synergies Forest productivity
下载PDF
Giant idiopathic renal arteriovenous fistula managed by coils and amplatzer device:Case report and literature review 被引量:1
20
作者 Prashant Nagpal Girish Bathla +4 位作者 Sachin S Saboo Ashish Khandelwal Abhishek Goyal Frank J Rybicki Michael L Steigner 《World Journal of Clinical Cases》 SCIE 2016年第11期364-368,共5页
An idiopathic renal arteriovenous(AV) fistula is a rare malformation of the kidney that may present insidiously with heart failure or hematuria.The treatment may be challenging due to large fistula size that may limit... An idiopathic renal arteriovenous(AV) fistula is a rare malformation of the kidney that may present insidiously with heart failure or hematuria.The treatment may be challenging due to large fistula size that may limit endovascular management.The authors report a case of an 85-year-old Caucasian woman who presented with acute heart failure and was found to have a right renal AV fistula.Since she had no prior history of renal intervention or trauma,a diagnosis of idiopathic renal AV fistula was made.She was managed by endoluminal occlusion using multiple stainless steel coils and Amplatzer vascular plug II device.The follow-up computed tomography showed complete occlusion of the fistula.This report highlights the late presentation of this rare disease and presents the utility of the combination of coils and Amplatzer device for management of a large fistula.It also reiterates that even if large,these fistulas can be managed by endovascular occlusion. 展开更多
关键词 Heart failure IDIOPATHIC ARTERIOVENOUS FISTULA ENDOVASCULAR management AMPLATZER device
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部