We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The ...We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The results show that the model well simulates vortex circulation associated with precipitating clouds. It is also proven that the vortex merging follows the precipitating cloud merging although vortices show the spatial and temporal differences. The convection vorticity vector is introduced to describe the merging processes. Two merging cases are identified during the 42-h simulation and are studied.展开更多
The concept of an integrated "lab on a chip" has long been a goal for the micro-electro-mechanical-systems(MEMS) community.This would entail the integration of not only the sampling and analysis of various f...The concept of an integrated "lab on a chip" has long been a goal for the micro-electro-mechanical-systems(MEMS) community.This would entail the integration of not only the sampling and analysis of various functions,but also the ability to transmit this information off the chip to a central repository.This paper describes the initial steps in the fabrication of a "lab on a chip" which would continually analyze blood sampled via microneedles using techniques such as nano plasmonics,specifically,concentrations of glucose.The analysis could then be transmitted off the chip using digital signal processing.This paper describes the analysis and optimization of the microneedle shape and size and the fabrication of the resulting needles in silicon using deep reactive ion etching(DRIE).The paper also describes the opportunities for fabrication of such needles in alternative materials and describes the issues that still have to be overcome before such an integrated device is realized.展开更多
Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- ...Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- fractures in the producing shales. The non-tectonic micro-fractures are different from tectonic fractures and are characterized by being irregular, curved, discontinuous, and randomly distributed. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. Two-dimensional computational modeling studies have been used in an initial attempt toward understanding how naturally random fractured reservoirs respond during hydraulic fracturing. The aim of the paper is to investigate the effect of random non-tectonic fractures on hydraulic fracturing. The numerical models with random non-tectonic micro-fractures are built by extracting the fractures of rock blocks after repeated heating and cooling, using a digital image process. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of random fractures;(3) cohesion of random fractures;(4) operational variables such as injection rate; and(5) variable injection rate technology. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in a natural fracture system. Three types of fracturing networks were observed from the studied simulations, and the results also show that variable injection rate technology is most promising for producing complex fracturing networks. This work strongly links the production technology and geomechanical evaluation. It can aid in the understanding and optimization of hydraulic fracturing simulations in naturally random fractured reservoirs.展开更多
文摘We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The results show that the model well simulates vortex circulation associated with precipitating clouds. It is also proven that the vortex merging follows the precipitating cloud merging although vortices show the spatial and temporal differences. The convection vorticity vector is introduced to describe the merging processes. Two merging cases are identified during the 42-h simulation and are studied.
文摘The concept of an integrated "lab on a chip" has long been a goal for the micro-electro-mechanical-systems(MEMS) community.This would entail the integration of not only the sampling and analysis of various functions,but also the ability to transmit this information off the chip to a central repository.This paper describes the initial steps in the fabrication of a "lab on a chip" which would continually analyze blood sampled via microneedles using techniques such as nano plasmonics,specifically,concentrations of glucose.The analysis could then be transmitted off the chip using digital signal processing.This paper describes the analysis and optimization of the microneedle shape and size and the fabrication of the resulting needles in silicon using deep reactive ion etching(DRIE).The paper also describes the opportunities for fabrication of such needles in alternative materials and describes the issues that still have to be overcome before such an integrated device is realized.
基金supported by the National Natural Science Foundation of China(Grant Nos.4122790141330643&41502294)+2 种基金China Postdoctoral Science Foundation Funded Project(Grants No.2015M571118)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB10030000XDB10030300&XDB10050400)
文摘Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in which the shale plays, core observations indicate abundant random non-tectonic micro- fractures in the producing shales. The non-tectonic micro-fractures are different from tectonic fractures and are characterized by being irregular, curved, discontinuous, and randomly distributed. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. Two-dimensional computational modeling studies have been used in an initial attempt toward understanding how naturally random fractured reservoirs respond during hydraulic fracturing. The aim of the paper is to investigate the effect of random non-tectonic fractures on hydraulic fracturing. The numerical models with random non-tectonic micro-fractures are built by extracting the fractures of rock blocks after repeated heating and cooling, using a digital image process. Simulations were conducted as a function of:(1) the in-situ stress ratio;(2) internal friction angle of random fractures;(3) cohesion of random fractures;(4) operational variables such as injection rate; and(5) variable injection rate technology. A sensitivity study reveals a number of interesting observations resulting from these parameters on the shear stimulation in a natural fracture system. Three types of fracturing networks were observed from the studied simulations, and the results also show that variable injection rate technology is most promising for producing complex fracturing networks. This work strongly links the production technology and geomechanical evaluation. It can aid in the understanding and optimization of hydraulic fracturing simulations in naturally random fractured reservoirs.
