The increasing stocks of public infrastructure and serious deterioration of infrastructure systems due to corrosion present great financial, safety, technical and operational challenges to government organizations in ...The increasing stocks of public infrastructure and serious deterioration of infrastructure systems due to corrosion present great financial, safety, technical and operational challenges to government organizations in charge of public infrastructure development and management. To meet those challenges, a performance-based life-cycle management model for reinforced concrete structures was proposed in this paper. This model predicts the life-cycle performance of infrastructure based on the corrosion-induced deterioration mechanism: condition index as well as performance limit states. A case study is provided to demonstrate the use of the proposed performance-based life-cycle cost management model.展开更多
The problem of sequential fault diagnosis is to construct a diagnosis tree that can isolate the failure sources with minimal test cost. Pervious sequential fault diagnosis strategy generating algorithms only consider ...The problem of sequential fault diagnosis is to construct a diagnosis tree that can isolate the failure sources with minimal test cost. Pervious sequential fault diagnosis strategy generating algorithms only consider the execution cost at application stage, which may result in a solution with poor quality from the view of life cycle cost. Furthermore, due to the fact that uncertain information exists extensively in the real-world systems, the tests are always imperfect. In order to reduce the cost of fault diagnosis in the realistic systems, the sequential fault diagnosis problem with imperfect tests considering life cycle cost is presented and formulated in this work, which is an intractable NP-hard AND/OR decision tree construction problem. An algorithm based on AND/OR graph search is proposed to solve this problem. Heuristic search based on information theory is applied to generate the sub-tree in the algorithm. Some practical issues such as the method to improve the computational efficiency and the diagnosis strategy with multi-outcome tests are discussed. The algorithm is tested and compared with previous algorithms on the simulated systems with different scales and uncertainty. Application on a wheel momentum system of a spacecraft is studied in detail. Both the simulation and application results suggest that the cost of the diagnosis strategy can be reduced significantly by using the proposed algorithm, especially when the placement cost of the tests constitutes a large part of the total cost.展开更多
India is having more than 500,000 villages of which about 85% have been electrified. But as per RGGVY (Rejiv Gandhi Grammen Vidyutikaran Yojana), the rate of village electrification is much lower as household connec...India is having more than 500,000 villages of which about 85% have been electrified. But as per RGGVY (Rejiv Gandhi Grammen Vidyutikaran Yojana), the rate of village electrification is much lower as household connectivity has been fairly low. The rest 15% villages and a larger proportion of households have to be electrified. Villages have been a major concern as cost of electrification is fairly high. The most favored alternative to any kind of users is generation of electricity from diesel generating sets and renewable sources of energy. But the capital cost of renewable energy equipments is fairly high. Gradually, there is a reduction in the prices of these systems due to availability of better technological options and they are becoming competitive to grid electricity. In this paper, an attempt has been made to calculate the cost of production of electricity from stand-alone, off-grid devices biomass gasifiers (both dual fuel and pure gas type) and compare with that of diesel generating sets by using the concept of LCC (life cycle costing) and Homer software. It is found that the cost of per unit electricity generation (kWh) has been always the lowest in comparison to diesel generating sets even if the price of biomass increases to some extent.展开更多
Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-a...Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water (δDsw), leaf water (δDlw), and leaf wax n-alkane (δDn-alkane) for woods and grasses. We found no significant differences in the δD values of soil water (P = 0.82) and leaf water (P= 0.74) between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.展开更多
The hydrocarbons and other organic compounds generated through abiogenic or inorganic processes are closely related to two science subjects, i.e., energy resources and life's origin and evolution. "The earth's prim...The hydrocarbons and other organic compounds generated through abiogenic or inorganic processes are closely related to two science subjects, i.e., energy resources and life's origin and evolution. "The earth's primordial abiogenic hydrocarbon theory" and "the serpentinization of abiogenic hydrocarbon theory" are the two mainstream theories in the field of related studies. Ser- pentinizafion generally occurs in slow expanding mid-ocean ridges and continental ophiolites tectonic environment, etc. The abiogenic hydrocarbons and other organic compounds formed through the serpentinization of ultramafic rocks provide energy and raw materials to support chemosynthetic microbial communities, which probably was the most important hydration reac- tion for the origin and early evolution of life. The superposition of biological and abiological processes creates big challenge to the identification of the abiogenic organic materials in serpentinite-hosted ecosystem. Whether abiotic (inorganic) process can form oil and gas resource is a difficult question that has been explored continuously by scientific community for more than a century but has not yet been solved. However, some important progress has been made. The prospecting practice of abiogenic hydrocarbons in commercial gases from the Songliao Basin, China, provides an important example for exploring abiogenic natural gas resources.展开更多
The outbreak of hotspot in social network may contain complex dynamic genesis. Using user behavior data from hotspots in social network, we study how different user groups play different roles for a hotspot topic. Fir...The outbreak of hotspot in social network may contain complex dynamic genesis. Using user behavior data from hotspots in social network, we study how different user groups play different roles for a hotspot topic. Firstly, by analyzing users' behavior records, we mine group situation that promotes the hotspot.Several major attributions in a hotspot outbreak, such as individual, peer and group triggers, are defined formally according to the view-point of social identity, social interaction, retweet depth and opinion leader. Secondly,for the problem of the uneven and sparse data in each stage of hotspot topic's life cycle, we propose a dynamic influence model based on grey system to formalize the effect of different groups. Then the process of hotspot evolution driven by distinct crowd is showed dynamically. The experimental result confirms that the model is able not only to qualify users' influence on a hotspot topic but also to predict effectively an upcoming change in a hotspot topic.展开更多
文摘The increasing stocks of public infrastructure and serious deterioration of infrastructure systems due to corrosion present great financial, safety, technical and operational challenges to government organizations in charge of public infrastructure development and management. To meet those challenges, a performance-based life-cycle management model for reinforced concrete structures was proposed in this paper. This model predicts the life-cycle performance of infrastructure based on the corrosion-induced deterioration mechanism: condition index as well as performance limit states. A case study is provided to demonstrate the use of the proposed performance-based life-cycle cost management model.
基金Project(C1320063131)supported by China Civil Space Foundation
文摘The problem of sequential fault diagnosis is to construct a diagnosis tree that can isolate the failure sources with minimal test cost. Pervious sequential fault diagnosis strategy generating algorithms only consider the execution cost at application stage, which may result in a solution with poor quality from the view of life cycle cost. Furthermore, due to the fact that uncertain information exists extensively in the real-world systems, the tests are always imperfect. In order to reduce the cost of fault diagnosis in the realistic systems, the sequential fault diagnosis problem with imperfect tests considering life cycle cost is presented and formulated in this work, which is an intractable NP-hard AND/OR decision tree construction problem. An algorithm based on AND/OR graph search is proposed to solve this problem. Heuristic search based on information theory is applied to generate the sub-tree in the algorithm. Some practical issues such as the method to improve the computational efficiency and the diagnosis strategy with multi-outcome tests are discussed. The algorithm is tested and compared with previous algorithms on the simulated systems with different scales and uncertainty. Application on a wheel momentum system of a spacecraft is studied in detail. Both the simulation and application results suggest that the cost of the diagnosis strategy can be reduced significantly by using the proposed algorithm, especially when the placement cost of the tests constitutes a large part of the total cost.
文摘India is having more than 500,000 villages of which about 85% have been electrified. But as per RGGVY (Rejiv Gandhi Grammen Vidyutikaran Yojana), the rate of village electrification is much lower as household connectivity has been fairly low. The rest 15% villages and a larger proportion of households have to be electrified. Villages have been a major concern as cost of electrification is fairly high. The most favored alternative to any kind of users is generation of electricity from diesel generating sets and renewable sources of energy. But the capital cost of renewable energy equipments is fairly high. Gradually, there is a reduction in the prices of these systems due to availability of better technological options and they are becoming competitive to grid electricity. In this paper, an attempt has been made to calculate the cost of production of electricity from stand-alone, off-grid devices biomass gasifiers (both dual fuel and pure gas type) and compare with that of diesel generating sets by using the concept of LCC (life cycle costing) and Homer software. It is found that the cost of per unit electricity generation (kWh) has been always the lowest in comparison to diesel generating sets even if the price of biomass increases to some extent.
文摘Many studies have observed that leaf wax δDn-alkane values differed significantly between woods and grasses in modern plants, with grasses D-depleted by 40 %0-70 ‰. The reasons for the differences in leaf wax δDn-alkane values between woods and grasses, however, remain unclear. In this study, we measured the δD values of soil water (δDsw), leaf water (δDlw), and leaf wax n-alkane (δDn-alkane) for woods and grasses. We found no significant differences in the δD values of soil water (P = 0.82) and leaf water (P= 0.74) between the two life forms of plants. Therefore, the differences in leaf wax δDn-alkane values between woods and grasses may correlate with inherent properties of different plant life forms, such as leaf structures, biosynthetic processes, and leaf morphologies. Moreover, it is also possible that soil water with different 6Dsw at different depths utilized by woods and grasses may be responsible for some of the differences in leaf wax δDn-alkane values between the two life forms of plants, if woods mainly use soil water from the 〉100 cm depth, whereas grasses mainly use soil water from the 〈100 cm depth. The results of this work allow us to better understand the leaf wax δDn-alkane values of different plant life forms in a region.
基金supported by National Natural Science Foundation of China (Grant Nos. 41172133, 41272146, 41103022)
文摘The hydrocarbons and other organic compounds generated through abiogenic or inorganic processes are closely related to two science subjects, i.e., energy resources and life's origin and evolution. "The earth's primordial abiogenic hydrocarbon theory" and "the serpentinization of abiogenic hydrocarbon theory" are the two mainstream theories in the field of related studies. Ser- pentinizafion generally occurs in slow expanding mid-ocean ridges and continental ophiolites tectonic environment, etc. The abiogenic hydrocarbons and other organic compounds formed through the serpentinization of ultramafic rocks provide energy and raw materials to support chemosynthetic microbial communities, which probably was the most important hydration reac- tion for the origin and early evolution of life. The superposition of biological and abiological processes creates big challenge to the identification of the abiogenic organic materials in serpentinite-hosted ecosystem. Whether abiotic (inorganic) process can form oil and gas resource is a difficult question that has been explored continuously by scientific community for more than a century but has not yet been solved. However, some important progress has been made. The prospecting practice of abiogenic hydrocarbons in commercial gases from the Songliao Basin, China, provides an important example for exploring abiogenic natural gas resources.
基金supported by National Basic Research Program of China(973 program)(Grant No.2013CB3296-06)National Natural Science Foundation of China(Grant No.61272400)+6 种基金Chongqing Innovative Team Fund for College Development Project(Grant No.KJTD201310)Chongqing Youth Innovative Talent Project(Grant No.cstc2013kjrc-qnrc40004)Ministry of Education of China and China Mobile Research Fund(Grant No.MCM20130351)Science and Technology Research Program of the Chongqing Municipal Education Committee(Grant No.KJ1500425)Wen Feng Foundation of CQUPT(Grant No.WF201403)Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory Open Subject(Grant No.ITD-U13002/KX132600009)Chongqing Graduate Research and Innovation Project(Grant No.CYS14146)
文摘The outbreak of hotspot in social network may contain complex dynamic genesis. Using user behavior data from hotspots in social network, we study how different user groups play different roles for a hotspot topic. Firstly, by analyzing users' behavior records, we mine group situation that promotes the hotspot.Several major attributions in a hotspot outbreak, such as individual, peer and group triggers, are defined formally according to the view-point of social identity, social interaction, retweet depth and opinion leader. Secondly,for the problem of the uneven and sparse data in each stage of hotspot topic's life cycle, we propose a dynamic influence model based on grey system to formalize the effect of different groups. Then the process of hotspot evolution driven by distinct crowd is showed dynamically. The experimental result confirms that the model is able not only to qualify users' influence on a hotspot topic but also to predict effectively an upcoming change in a hotspot topic.