Hydraulic fracturing techniques are commonly used to enhance the production of tight reservoirs.Generally,the effect of hydraulic fracturing can be appraised through hydraulic fracturing experiments in the laboratory,...Hydraulic fracturing techniques are commonly used to enhance the production of tight reservoirs.Generally,the effect of hydraulic fracturing can be appraised through hydraulic fracturing experiments in the laboratory,in which acoustic emission(AE)is often used to monitor the fracturing process.At present,the number of AE events and spatial distribution of AE locations are the two main factors commonly conside red in hydraulic fracturing effectiveness evaluatio n.Howeve r,these commonly used evaluation methods overlook two crucial aspects:the connectivity among fractures and the tensile and shear properties of fractures induced by hydraulic fracturing.In this technical note,we consider the influence of these two previously overlooked aspects on the evaluation of hydraulic fracturing effectiveness by establishing a connected fracture model using AE data.The proposed approach links up AE events based on their spatio-temporal relationship and builds a fracture network called the connection model.Then,the characteristic of the fracture network is represented by the fractal dimension to reveal the complexity of fractures in the network.We extract the tensile-shear properties of each fracture based on the inversion of AE events'focal mechanism.Finally,based on the pre-known fracturing effectiveness of a fracture network,we compare the connection model of AE events in several triaxial hydraulic experiments.Our findings indicate that a comprehensive evaluation of hydraulic fracturing effectiveness can be achieved by considering both the connectivity of AE locations and the tensile-shear properties of AE events.This work aims to provide a more rational method for characterizing rock fracture networks and evaluating rock fracturing effects using AE data.展开更多
To construct an effective circular mix-culture model and investigate its culture capacity,we established one small and one large systems,with white shrimp(Litopenaeus vannamei)and razor clam(Sinonovacula constricta)cu...To construct an effective circular mix-culture model and investigate its culture capacity,we established one small and one large systems,with white shrimp(Litopenaeus vannamei)and razor clam(Sinonovacula constricta)cultured in separate ponds.The culture water from the L.vannamei was pumped to the S.constricta,and the culture water from the S.constricta overflowed back into the L.vannamei via gravity.In trial I,we tested four culture densities(groups 1–4),and monitored water quality,growth indices,and digestive and immune enzyme activities.From the results,the nitrogen and phosphorus levels generally increased then declined after 56 days,and were lower in groups 1 and 2.The specific growth rate of group 2 was the highest.After 56 days,activities of four digestive enzymes were increased in group 2,and lysozyme activity was significantly decreased in S.constricta in groups 1–4;Alkaline phosphatase activity of L.vannamei was increased in group 3,but decreased in S.constricta in groups 2–4;Acid phosphatase activity was significantly higher in groups 1–3(P<0.05),while SOD and CAT activities were significantly elevated in group 2(P<0.05).Thus,we applied group 2 density for trial II.In trial II,nitrogen and phosphorus concentrations declined significantly during the latter stages,and growth indices were higher than the control(P<0.05).The yields of L.vannamei and S.constricta were significantly higher than the control(P<0.05).The results revealed a good circular mix-culture system with the optimal culture capacity for L.vannamei(40 ind m^(−2))and S.constricta(300 ind m^(−2)),which provided a reference for the future culture of them.展开更多
Because connection number can express and process synthetic uncertainties caused by various uncertainties in the transmission network planning, a connection number model (CNM) was presented to compare the values of co...Because connection number can express and process synthetic uncertainties caused by various uncertainties in the transmission network planning, a connection number model (CNM) was presented to compare the values of connection number logically. This paper proposed a novel model for transmission network flexible planning with uncertainty. In the proposed planning model both certainty and uncertainty information were included, and the cost-benefit analysis method was used to evaluate the candidate schemes in the objective function. Its good adaptability and flexibility were illustrated through two examples.展开更多
基金financial support from the subprojects of the Natural Science Foundation of China(No.42302326)the Shenzhen Science and Technology Program(JCYJ20220530113612028)+1 种基金the National Key Research and Development Program of China(Grant No.2023YFC3707905)the Fundamental Research Funds for the Central Universities(JZ2025HGTB0191)。
文摘Hydraulic fracturing techniques are commonly used to enhance the production of tight reservoirs.Generally,the effect of hydraulic fracturing can be appraised through hydraulic fracturing experiments in the laboratory,in which acoustic emission(AE)is often used to monitor the fracturing process.At present,the number of AE events and spatial distribution of AE locations are the two main factors commonly conside red in hydraulic fracturing effectiveness evaluatio n.Howeve r,these commonly used evaluation methods overlook two crucial aspects:the connectivity among fractures and the tensile and shear properties of fractures induced by hydraulic fracturing.In this technical note,we consider the influence of these two previously overlooked aspects on the evaluation of hydraulic fracturing effectiveness by establishing a connected fracture model using AE data.The proposed approach links up AE events based on their spatio-temporal relationship and builds a fracture network called the connection model.Then,the characteristic of the fracture network is represented by the fractal dimension to reveal the complexity of fractures in the network.We extract the tensile-shear properties of each fracture based on the inversion of AE events'focal mechanism.Finally,based on the pre-known fracturing effectiveness of a fracture network,we compare the connection model of AE events in several triaxial hydraulic experiments.Our findings indicate that a comprehensive evaluation of hydraulic fracturing effectiveness can be achieved by considering both the connectivity of AE locations and the tensile-shear properties of AE events.This work aims to provide a more rational method for characterizing rock fracture networks and evaluating rock fracturing effects using AE data.
基金supported by the National Key Research and Development Plan(No.2019YFD0900400)the Ear marked Fund for Modern Agro-Industry Technology Research System,China(No.CARS-47)sponsored by the K.C.Wong Magna Fund in Ningbo University.
文摘To construct an effective circular mix-culture model and investigate its culture capacity,we established one small and one large systems,with white shrimp(Litopenaeus vannamei)and razor clam(Sinonovacula constricta)cultured in separate ponds.The culture water from the L.vannamei was pumped to the S.constricta,and the culture water from the S.constricta overflowed back into the L.vannamei via gravity.In trial I,we tested four culture densities(groups 1–4),and monitored water quality,growth indices,and digestive and immune enzyme activities.From the results,the nitrogen and phosphorus levels generally increased then declined after 56 days,and were lower in groups 1 and 2.The specific growth rate of group 2 was the highest.After 56 days,activities of four digestive enzymes were increased in group 2,and lysozyme activity was significantly decreased in S.constricta in groups 1–4;Alkaline phosphatase activity of L.vannamei was increased in group 3,but decreased in S.constricta in groups 2–4;Acid phosphatase activity was significantly higher in groups 1–3(P<0.05),while SOD and CAT activities were significantly elevated in group 2(P<0.05).Thus,we applied group 2 density for trial II.In trial II,nitrogen and phosphorus concentrations declined significantly during the latter stages,and growth indices were higher than the control(P<0.05).The yields of L.vannamei and S.constricta were significantly higher than the control(P<0.05).The results revealed a good circular mix-culture system with the optimal culture capacity for L.vannamei(40 ind m^(−2))and S.constricta(300 ind m^(−2)),which provided a reference for the future culture of them.
基金the National Natural Science Founda-tion of China (No. 50177017)the Shanghai Key Scienceand Technology Research Program (No. 041612012)
文摘Because connection number can express and process synthetic uncertainties caused by various uncertainties in the transmission network planning, a connection number model (CNM) was presented to compare the values of connection number logically. This paper proposed a novel model for transmission network flexible planning with uncertainty. In the proposed planning model both certainty and uncertainty information were included, and the cost-benefit analysis method was used to evaluate the candidate schemes in the objective function. Its good adaptability and flexibility were illustrated through two examples.
