During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2)...During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2) injectivity and migration. Different values of three characteristic parameters for capillary pressure function (air entry pressure, empirical parameter m and liquid residual saturation) as well as input absolute value of maximum capillary are chosen in numerical simulation to figure out their effects on salt precipitation. Verma & Pruess model is then used for quantifying permeability impairment. Results show that permeability decreases with higher air entry pressure, larger liquid residual saturation, and especially smaller value of empirical parameter m. To enhance CO_(2) injectivity and avoid blocking of CO_(2) migration, a homogenous formation with large pore size should be chosen before CO_(2) injection into deep saline aquifer.展开更多
In order to optimize the embedded system implementation for Ethernet-based computer numerical control （CNC） system, it is very necessary to establish the performance analysis model and further adopt the codesign met...In order to optimize the embedded system implementation for Ethernet-based computer numerical control （CNC） system, it is very necessary to establish the performance analysis model and further adopt the codesign method from the control, communication and computing perspectives. On the basis of analyzing real-time Ethemet, system architecture, time characteristic parameters of control-loop ere, a performance analysis model for real-time Ethemet-based CNC system was proposed, which is able to include the timing effects caused by the implementation platform in the simulation. The key for establishing the model is accomplished by designing the error analysis module and the controller nodes. Under the restraint of CPU resource and communication bandwidth, the experiment with a case study was conducted, and the results show that if the deadline miss ratio of data packets is 0.2%, then the percentage error is 1.105%. The proposed model can be used at several stages of CNC system development.展开更多
基金Foundation item:Project(51179060)supported by the National Natural Science Foundation of ChinaProject(20110094130002)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2) injectivity and migration. Different values of three characteristic parameters for capillary pressure function (air entry pressure, empirical parameter m and liquid residual saturation) as well as input absolute value of maximum capillary are chosen in numerical simulation to figure out their effects on salt precipitation. Verma & Pruess model is then used for quantifying permeability impairment. Results show that permeability decreases with higher air entry pressure, larger liquid residual saturation, and especially smaller value of empirical parameter m. To enhance CO_(2) injectivity and avoid blocking of CO_(2) migration, a homogenous formation with large pore size should be chosen before CO_(2) injection into deep saline aquifer.
基金Projects(50875090,50905063) supported by the National Natural Science Foundation of ChinaProject(2009AA04Z111) supported by the National High Technology Research and Development Program of China+2 种基金Project(20090460769) supported by China Postdoctoral Science FoundationProject(2011ZM0070) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(S2011010001155) supported by the Natural Science Foundation of Guangdong Province,China
文摘In order to optimize the embedded system implementation for Ethernet-based computer numerical control （CNC） system, it is very necessary to establish the performance analysis model and further adopt the codesign method from the control, communication and computing perspectives. On the basis of analyzing real-time Ethemet, system architecture, time characteristic parameters of control-loop ere, a performance analysis model for real-time Ethemet-based CNC system was proposed, which is able to include the timing effects caused by the implementation platform in the simulation. The key for establishing the model is accomplished by designing the error analysis module and the controller nodes. Under the restraint of CPU resource and communication bandwidth, the experiment with a case study was conducted, and the results show that if the deadline miss ratio of data packets is 0.2%, then the percentage error is 1.105%. The proposed model can be used at several stages of CNC system development.
