To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesu...To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesulia axillaris Roxburgh was found to be the most serious,followed by Echinochloa cruss-galli L.Beauv and Echinochloa colonum L.Link,while Fimbristylis miliaceae L.Vahl and Cyperus iria L.were moderate weeds of the rice fields.C.axillaris had the lowest leaf construction cost (LCC) both on a mass basis (1.15 g/g) and on a unit area basis (22.93 g/m2).Comparatively higher specific leaf area,photosynthetic rate,photosynthetic nitrogen use efficiency,leaf area ratio and leaf area index provided C.axillaris with further competitive advantage.Low LCC suggests that weeds utilize carbon resource more efficiently than the crop and potentially spend the saved energy on other competitive strategies viz.seed production,biomass production and high relative growth rate,which results in low crop yield and increase in weed seed bank.展开更多
In a real estate project, the estimated cost of construction and the revenues generally represent together the most important values of its feasibility study. When a decision of undertaking a project is made, often th...In a real estate project, the estimated cost of construction and the revenues generally represent together the most important values of its feasibility study. When a decision of undertaking a project is made, often there are few definitions of what is about to be constructed, and frequently not enough to ensure the accuracy of the estimated costs. Considering a global tendency on reducing margins of return over the real estate markets, slight variations of the construction cost can jeopardize the success of the whole real estate enterprise and even the financial stability of the builder or of the developer. This article aims at presenting a method of estimating the building construction costs applicable at the stage of feasibility studies, being able to provide acceptable errors.展开更多
The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation m...The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on Offshore Technology Conference(OTC) and Society of Petroleum Engineers(SPE) industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.展开更多
Ground condition and construction (excavation and support) time and costs are the key factors in decision-making during planning and design phases of a tunnel project. An innovative methodology for probabilistic est...Ground condition and construction (excavation and support) time and costs are the key factors in decision-making during planning and design phases of a tunnel project. An innovative methodology for probabilistic estimation of ground condition and construction time and costs is proposed, which is an integration of the ground prediction approach based on Markov process, and the time and cost variance analysis based on Monte-Carlo (MC) simulation. The former provides the probabilistic description of ground classification along tunnel alignment according to the geological information revealed from geological profile and boreholes. The latter provides the probabilistic description of the expected construction time and costs for each operation according to the survey feedbacks from experts. Then an engineering application to Hamro tunnel is presented to demonstrate how the ground condition and the construction time and costs are estimated in a probabilistic way. In most items, in order to estimate the data needed for this methodology, a number of questionnaires are distributed among the tunneling experts and finally the mean values of the respondents are applied. These facilitate both the owners and the contractors to be aware of the risk that they should carry before construction, and are useful for both tendering and bidding.展开更多
Logistics is supposed to be the important source of profits for the enterprises besides reducing material consumption and improving labor productivity. Transportation costs, distribution center construction costs, ord...Logistics is supposed to be the important source of profits for the enterprises besides reducing material consumption and improving labor productivity. Transportation costs, distribution center construction costs, ordering costs, safe inventory costs and inventory holding costs are the important parts of the total logistics costs. In this paper, based on the research results of LMRP( location model of risk pooling) location with fixed construction cost, the LMRPVCC ( location model of risk pooling based on variable construction cost) will be introduced. Applying particle swarm optimization to several computational instances, the authors find the suboptimum solution of the model.展开更多
Aims In Mediterranean-type ecosystem,the Cape Fynbos,legumes may be able to switch between soil N and atmospheric N_(2) sources during growth to adjust the carbon costs of N acquisition.This study investigated the uti...Aims In Mediterranean-type ecosystem,the Cape Fynbos,legumes may be able to switch between soil N and atmospheric N_(2) sources during growth to adjust the carbon costs of N acquisition.This study investigated the utilization of different inorganic N sources by Virgilia divaricata,a native legume from the Mediterranean-type ecosystem of the Cape Floristic Region.Methods Plants were cultivated in sterile quartz sand,supplied with 25%strength Long Ashton nutrient solution,modified to contain 500μM Phosphate.At the phosphate level(500μM),plants were treated with 500μM NH_(4)NO_(3)(treatment named N),or grown in N-free nutrient solution and inoculated with effective Burkholderia sp.(Bact.)or treated with combined N sources(500μM NH_(4)NO_(3))and inoculated with effective Burkholderia sp.(N+Bact.).Important Findings The application of NH_(4)NO_(3) to the legumes resulted in a greater increase in plant dry matter.Carbon construction costs were higher in plants that were supplied with mineral and symbiotic N sources.Maximum photosynthetic rates per leaf area was maintained,irrespective of the N sources.Although the plant roots were nodulated,the plant dependence on N_(2) fixation decreased with addition of N.Roots and nodules of the plants solely reliant on N_(2) fixation showed an increase in glutamine content.These results show that V.divaricata is highly adapted for growth at the forest margin.Fynbos and possibly anthropic soils by utilizing both atmospheric and soil N sources.展开更多
With the combination of modern quantitative analysis method and enterprise inputoutput model,in this paper we make a scientific analysis on the effect to product profit tax from the change of internal and external imp...With the combination of modern quantitative analysis method and enterprise inputoutput model,in this paper we make a scientific analysis on the effect to product profit tax from the change of internal and external important factors of enterprise,and some important results hare been given.展开更多
文摘To understand the reason for the success of weeds,we investigated the energetic cost of leaf construction,and certain ecophysiological traits of rice and its dominant weeds.On physiological basis among all weeds,Caesulia axillaris Roxburgh was found to be the most serious,followed by Echinochloa cruss-galli L.Beauv and Echinochloa colonum L.Link,while Fimbristylis miliaceae L.Vahl and Cyperus iria L.were moderate weeds of the rice fields.C.axillaris had the lowest leaf construction cost (LCC) both on a mass basis (1.15 g/g) and on a unit area basis (22.93 g/m2).Comparatively higher specific leaf area,photosynthetic rate,photosynthetic nitrogen use efficiency,leaf area ratio and leaf area index provided C.axillaris with further competitive advantage.Low LCC suggests that weeds utilize carbon resource more efficiently than the crop and potentially spend the saved energy on other competitive strategies viz.seed production,biomass production and high relative growth rate,which results in low crop yield and increase in weed seed bank.
文摘In a real estate project, the estimated cost of construction and the revenues generally represent together the most important values of its feasibility study. When a decision of undertaking a project is made, often there are few definitions of what is about to be constructed, and frequently not enough to ensure the accuracy of the estimated costs. Considering a global tendency on reducing margins of return over the real estate markets, slight variations of the construction cost can jeopardize the success of the whole real estate enterprise and even the financial stability of the builder or of the developer. This article aims at presenting a method of estimating the building construction costs applicable at the stage of feasibility studies, being able to provide acceptable errors.
基金provided through the U.S. Department of the Interior, Bureau of Ocean Energy Management
文摘The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on Offshore Technology Conference(OTC) and Society of Petroleum Engineers(SPE) industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.
文摘Ground condition and construction (excavation and support) time and costs are the key factors in decision-making during planning and design phases of a tunnel project. An innovative methodology for probabilistic estimation of ground condition and construction time and costs is proposed, which is an integration of the ground prediction approach based on Markov process, and the time and cost variance analysis based on Monte-Carlo (MC) simulation. The former provides the probabilistic description of ground classification along tunnel alignment according to the geological information revealed from geological profile and boreholes. The latter provides the probabilistic description of the expected construction time and costs for each operation according to the survey feedbacks from experts. Then an engineering application to Hamro tunnel is presented to demonstrate how the ground condition and the construction time and costs are estimated in a probabilistic way. In most items, in order to estimate the data needed for this methodology, a number of questionnaires are distributed among the tunneling experts and finally the mean values of the respondents are applied. These facilitate both the owners and the contractors to be aware of the risk that they should carry before construction, and are useful for both tendering and bidding.
基金supported by the National Planning Office of Philos-ophy and Social Sciences under Grant No. 07XJY015Shaanxi Provincial Department of Education under Grant No.06JK056
文摘Logistics is supposed to be the important source of profits for the enterprises besides reducing material consumption and improving labor productivity. Transportation costs, distribution center construction costs, ordering costs, safe inventory costs and inventory holding costs are the important parts of the total logistics costs. In this paper, based on the research results of LMRP( location model of risk pooling) location with fixed construction cost, the LMRPVCC ( location model of risk pooling based on variable construction cost) will be introduced. Applying particle swarm optimization to several computational instances, the authors find the suboptimum solution of the model.
基金DST/NRF-Center of Excellence for Tree Health and Biotechnology,based at the University of Pretoria.(grant number 85630)。
文摘Aims In Mediterranean-type ecosystem,the Cape Fynbos,legumes may be able to switch between soil N and atmospheric N_(2) sources during growth to adjust the carbon costs of N acquisition.This study investigated the utilization of different inorganic N sources by Virgilia divaricata,a native legume from the Mediterranean-type ecosystem of the Cape Floristic Region.Methods Plants were cultivated in sterile quartz sand,supplied with 25%strength Long Ashton nutrient solution,modified to contain 500μM Phosphate.At the phosphate level(500μM),plants were treated with 500μM NH_(4)NO_(3)(treatment named N),or grown in N-free nutrient solution and inoculated with effective Burkholderia sp.(Bact.)or treated with combined N sources(500μM NH_(4)NO_(3))and inoculated with effective Burkholderia sp.(N+Bact.).Important Findings The application of NH_(4)NO_(3) to the legumes resulted in a greater increase in plant dry matter.Carbon construction costs were higher in plants that were supplied with mineral and symbiotic N sources.Maximum photosynthetic rates per leaf area was maintained,irrespective of the N sources.Although the plant roots were nodulated,the plant dependence on N_(2) fixation decreased with addition of N.Roots and nodules of the plants solely reliant on N_(2) fixation showed an increase in glutamine content.These results show that V.divaricata is highly adapted for growth at the forest margin.Fynbos and possibly anthropic soils by utilizing both atmospheric and soil N sources.
文摘With the combination of modern quantitative analysis method and enterprise inputoutput model,in this paper we make a scientific analysis on the effect to product profit tax from the change of internal and external important factors of enterprise,and some important results hare been given.