An analytical algorithm was presented for the exact computation of the probability distribution of the project completion time in stochastic networks,where the activity durations are mutually independent and continuou...An analytical algorithm was presented for the exact computation of the probability distribution of the project completion time in stochastic networks,where the activity durations are mutually independent and continuously distributed random variables. Firstly,stochastic activity networks were modeled as continuous-time Markov process with a single absorbing state by the well-know method of supplementary variables and the time changed from the initial state to absorbing state is equal to the project completion time.Then,the Markov process was regarded as a special case of Markov skeleton process.By taking advantage of the backward equations of Markov skeleton processes,a backward algorithm was proposed to compute the probability distribution of the project completion time.Finally,a numerical example was solved to demonstrate the performance of the proposed methodology.The results show that the proposed algorithm is capable of computing the exact distribution function of the project completion time,and the expectation and variance are obtained.展开更多
The process of engaging private sector in the provision of public infrastructure can improve economic value in service delivery and enable the government to utilize the capabilities and expertise held by private secto...The process of engaging private sector in the provision of public infrastructure can improve economic value in service delivery and enable the government to utilize the capabilities and expertise held by private sector. This has a positive impact on the public in terms of improving their well-being. This literature review attempts to compare the challenges encountered in implementation of PPP projects across the world, with a view to determining cross cutting challenges and recommendations for developing countries. A literature review was conducted for empirical studies focusing on construction projects. The studies are reviewed by analyzing the methodology used and conclusions made to identify the geographical study area, Public Private Partnership project financing model, emerging challenges and recommendation for future project management. The literature search was based on four keywords: construction projects, completion of construction projects, public private partnership, challenges in construction projects. Thus, a total of 11 empirical studies were identified for review in Europe, Asia and Africa. The review revealed that most risk factors affecting project completion can be categorized as human and organizational factors and unknown geotechnical conditions that were not known beforehand. Specifically, project owners’ interference was also attributable to delays with the delays having significant implications for project execution. Risks have great impact on the performance of construction projects because they affect their quality, time and cost. The general remedy to such potential risk factors is adoption of reliable prediction mechanisms which would estimate those factors using a probabilistic model that does not rely on expert judgments as they tend to be unreliable.展开更多
On February 24, 1993, when the appraisal meeting of the Sino-Japanese Joint Research Project of Well-off Household Residences was held in Beijing, Person-in-charge from the China Building Technology Development and Re...On February 24, 1993, when the appraisal meeting of the Sino-Japanese Joint Research Project of Well-off Household Residences was held in Beijing, Person-in-charge from the China Building Technology Development and Research Centre and the Japan International Cooperation Undertakings Group signed the project appraisal report. It marked the successful completion of this three-year joint research project.展开更多
On April 16, the 500-kV Jing’an transmission & substation project in Shanghai, a super-large, multi-voltage level, all-underground, full digital intelligent substation, was completed and put into operation,
Renovation of the 650,000-ton ethylene unit was wound up at Yangtze Petrochemical Company Limited on July 26, which draws an investment of 4.352 billion yuan. The renovation project boosts the annual ethylene producti...Renovation of the 650,000-ton ethylene unit was wound up at Yangtze Petrochemical Company Limited on July 26, which draws an investment of 4.352 billion yuan. The renovation project boosts the annual ethylene production capacity of Yangtze Company to 650,000 tons from 400,000 tons, the polyethylene and polypropylene capacity to 400,000 tons from 200,000 tons, the butadiene capacity to 200,000 tons from 100,000 tons and the gasoline hydrorefining capacity to 500,000 tons from 300,000 tons.展开更多
On December 2, 2009, Unit 1 of Huaneng Yingkou Cogeneration Plant smoothly passed 168-hour triaoperation. 11 days later, Unit 2 also successfully passed the trial operation. The project
It has been proved that the vanishing of Tare homology is a sufficient condition for the derived depth formula to hold in [J. Pure Appl. Algebra, 219, 464-481 （2015）]. In this paper, we inves- tigate when Tate homol...It has been proved that the vanishing of Tare homology is a sufficient condition for the derived depth formula to hold in [J. Pure Appl. Algebra, 219, 464-481 （2015）]. In this paper, we inves- tigate when Tate homology vanishes by studying the stable homology theory for complexes. Properties such as the balancedness and vanishing of stable homology for complexes are studied. Our results show that the vanishing of this homology can detect finiteness of homological dimensions of complexes and regularness of rings.展开更多
基金Project(10671212) supported by the National Natural Science Foundation of ChinaProject(20050533036) supported by the Specialized Research Found for the Doctoral Program Foundation of Higher Education of China
文摘An analytical algorithm was presented for the exact computation of the probability distribution of the project completion time in stochastic networks,where the activity durations are mutually independent and continuously distributed random variables. Firstly,stochastic activity networks were modeled as continuous-time Markov process with a single absorbing state by the well-know method of supplementary variables and the time changed from the initial state to absorbing state is equal to the project completion time.Then,the Markov process was regarded as a special case of Markov skeleton process.By taking advantage of the backward equations of Markov skeleton processes,a backward algorithm was proposed to compute the probability distribution of the project completion time.Finally,a numerical example was solved to demonstrate the performance of the proposed methodology.The results show that the proposed algorithm is capable of computing the exact distribution function of the project completion time,and the expectation and variance are obtained.
文摘The process of engaging private sector in the provision of public infrastructure can improve economic value in service delivery and enable the government to utilize the capabilities and expertise held by private sector. This has a positive impact on the public in terms of improving their well-being. This literature review attempts to compare the challenges encountered in implementation of PPP projects across the world, with a view to determining cross cutting challenges and recommendations for developing countries. A literature review was conducted for empirical studies focusing on construction projects. The studies are reviewed by analyzing the methodology used and conclusions made to identify the geographical study area, Public Private Partnership project financing model, emerging challenges and recommendation for future project management. The literature search was based on four keywords: construction projects, completion of construction projects, public private partnership, challenges in construction projects. Thus, a total of 11 empirical studies were identified for review in Europe, Asia and Africa. The review revealed that most risk factors affecting project completion can be categorized as human and organizational factors and unknown geotechnical conditions that were not known beforehand. Specifically, project owners’ interference was also attributable to delays with the delays having significant implications for project execution. Risks have great impact on the performance of construction projects because they affect their quality, time and cost. The general remedy to such potential risk factors is adoption of reliable prediction mechanisms which would estimate those factors using a probabilistic model that does not rely on expert judgments as they tend to be unreliable.
文摘On February 24, 1993, when the appraisal meeting of the Sino-Japanese Joint Research Project of Well-off Household Residences was held in Beijing, Person-in-charge from the China Building Technology Development and Research Centre and the Japan International Cooperation Undertakings Group signed the project appraisal report. It marked the successful completion of this three-year joint research project.
文摘On April 16, the 500-kV Jing’an transmission & substation project in Shanghai, a super-large, multi-voltage level, all-underground, full digital intelligent substation, was completed and put into operation,
文摘Renovation of the 650,000-ton ethylene unit was wound up at Yangtze Petrochemical Company Limited on July 26, which draws an investment of 4.352 billion yuan. The renovation project boosts the annual ethylene production capacity of Yangtze Company to 650,000 tons from 400,000 tons, the polyethylene and polypropylene capacity to 400,000 tons from 200,000 tons, the butadiene capacity to 200,000 tons from 100,000 tons and the gasoline hydrorefining capacity to 500,000 tons from 300,000 tons.
文摘On December 2, 2009, Unit 1 of Huaneng Yingkou Cogeneration Plant smoothly passed 168-hour triaoperation. 11 days later, Unit 2 also successfully passed the trial operation. The project
基金Supported by National Natural Science Foundation of China(Grant Nos.11261050,11361051 and 11501451)Program for New Century Excellent Talents in University(Grant No.NCET-13-0957)
文摘It has been proved that the vanishing of Tare homology is a sufficient condition for the derived depth formula to hold in [J. Pure Appl. Algebra, 219, 464-481 （2015）]. In this paper, we inves- tigate when Tate homology vanishes by studying the stable homology theory for complexes. Properties such as the balancedness and vanishing of stable homology for complexes are studied. Our results show that the vanishing of this homology can detect finiteness of homological dimensions of complexes and regularness of rings.
