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
The existence of opportunistic behavior by contractors or sub-contractors in the bidding process encouraged by the governance structure of construction companies as well as the kind of relationship that exist between ...The existence of opportunistic behavior by contractors or sub-contractors in the bidding process encouraged by the governance structure of construction companies as well as the kind of relationship that exist between contractors and clients is thought to have some bearing on the rising construction cost observed in some regions of Sweden. Three hypotheses that are intended to test the impact that long run relationship between contractors and developers, vertically integrated firms, and the increase of international competition could have on the construction cost increase levels were tested on a predetermined number of projects from six cities in different regions. The semi-structured survey produces inconclusive results. Long run and collaborative relationship was prevalent in small region though respondents in this region did not draw strong connection between construction cost increase levels and the kind of observed relationship. In Stockholm region, short-term relationship was mostly prevalent. Vertical integration and foreign competition impacts on construction costs were not significant in either region.展开更多
Computer technology has been comprehensively popularized in all walks of life with its continuous development. The construction cost management industry is surely no exception. To improve the application of computer t...Computer technology has been comprehensively popularized in all walks of life with its continuous development. The construction cost management industry is surely no exception. To improve the application of computer technology in construction cost management industry, this thesis would respectively discuss and analyze the importance of computer technology application in construction cost management, status quo of computer technology application in construction cost management, measures of improving computer technology application in construction cost management as well as the development prospect of computer technology application in construction cost management. The author is striving to arouse the attention and exploration of relevant departments as well as practitioners in the same industry.展开更多
Building construction projects generally needs a long period, and there are many fixed factors in the process of building, therefore, the management of the project cost is a little difficult. On the basis that the qua...Building construction projects generally needs a long period, and there are many fixed factors in the process of building, therefore, the management of the project cost is a little difficult. On the basis that the quality of construction is not affected, the effective management of the project cost can effectively control the costs so that the economic and social benefits of the construction unit will be raised, and then continue to promote the development of construction industry in China.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
An overview of the delelopment of approaches to construction cost and price forcasting since the 1950’s is given. First, second and third generation models can be identified, but they all have shortcomings. This pape...An overview of the delelopment of approaches to construction cost and price forcasting since the 1950’s is given. First, second and third generation models can be identified, but they all have shortcomings. This paper puts forward a new model, fuzzy calculation model, based on lots of data of the finished proiects. Through actual application, it is proved that the model is accurate and quick in calcalation of construction.展开更多
Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the ...Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the understory of closed forests, indicating the plant's performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate (RGR), leaf root ratio (LRR), leaf area ratio (LAR), total leaf area, and lower root: shoot ratio (RSR). Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic energy use efficiency (PEUE) especially in low light and (or) unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency (WUE) indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and(or) light limited conditions, in which higher leaf construction cost(CC) compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected.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The existence of opportunistic behavior by contractors or sub-contractors in the bidding process encouraged by the governance structure of construction companies as well as the kind of relationship that exist between contractors and clients is thought to have some bearing on the rising construction cost observed in some regions of Sweden. Three hypotheses that are intended to test the impact that long run relationship between contractors and developers, vertically integrated firms, and the increase of international competition could have on the construction cost increase levels were tested on a predetermined number of projects from six cities in different regions. The semi-structured survey produces inconclusive results. Long run and collaborative relationship was prevalent in small region though respondents in this region did not draw strong connection between construction cost increase levels and the kind of observed relationship. In Stockholm region, short-term relationship was mostly prevalent. Vertical integration and foreign competition impacts on construction costs were not significant in either region.
文摘Computer technology has been comprehensively popularized in all walks of life with its continuous development. The construction cost management industry is surely no exception. To improve the application of computer technology in construction cost management industry, this thesis would respectively discuss and analyze the importance of computer technology application in construction cost management, status quo of computer technology application in construction cost management, measures of improving computer technology application in construction cost management as well as the development prospect of computer technology application in construction cost management. The author is striving to arouse the attention and exploration of relevant departments as well as practitioners in the same industry.
文摘Building construction projects generally needs a long period, and there are many fixed factors in the process of building, therefore, the management of the project cost is a little difficult. On the basis that the quality of construction is not affected, the effective management of the project cost can effectively control the costs so that the economic and social benefits of the construction unit will be raised, and then continue to promote the development of construction industry in China.
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.
文摘An overview of the delelopment of approaches to construction cost and price forcasting since the 1950’s is given. First, second and third generation models can be identified, but they all have shortcomings. This paper puts forward a new model, fuzzy calculation model, based on lots of data of the finished proiects. Through actual application, it is proved that the model is accurate and quick in calcalation of construction.
基金The author is grateful to Dr Feng Yulong, the teachers and students at the Qujing normal university for enabling me to carry out this experiment. The study was founded by the Project of the National Natural Science Foundation of China (30670394), the Applied Basic Study Project of Yunnan Province (2007C107M),
文摘Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the understory of closed forests, indicating the plant's performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate (RGR), leaf root ratio (LRR), leaf area ratio (LAR), total leaf area, and lower root: shoot ratio (RSR). Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic energy use efficiency (PEUE) especially in low light and (or) unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency (WUE) indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and(or) light limited conditions, in which higher leaf construction cost(CC) compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected.
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.