Hypoxia preconditioning （HPC） is associated with many complicated pathophysiological and biochemical processes that integrated and regulated via molecular levels. HPC could protect cells, tissues, organs and systems...Hypoxia preconditioning （HPC） is associated with many complicated pathophysiological and biochemical processes that integrated and regulated via molecular levels. HPC could protect cells, tissues, organs and systems from hypoxia injury, but up to date, the molecular mechanism still remained unclear. The acute and repetitive hy- poxia preconditioning model was constructed and the related parameters were observed. The high-throughput mi- croarray analysis and multiple bioinformatics were used to explore the differentially expressed genes in HPC mice brain and the related gene network, pathways and biological processes related to HPC. The 2D-DIGE coupled with MALDI-TOF/TOF-MS was performed to identify these proteins that were differentially expressed during HPC. The UPLC-HRMS based metabolomics method was utilized to explore the key endogenous metabolites and metabolic pathways related to HPC. The results showed that （1） 1175 differentially expressed genes in HPC mice brain were identified. Fourteen of these genes were the related hub genes for HPC, including Cacna2dl, Grin2a, Npylr, Mef2c, Epha4, Rxfpl, Chrm3, Pdela, Atp2b4, Glral, Idil , Fgfl, Grin2b and Cda. The change trends of all the detected genes by RT-PCR were consistent with the data of gene chips. There were 113 significant functions up- regulated and 138 significant functions down-regulated in HPC mice. （2） About 2100 proteins were revealed via the gel imaging and spot detection. 66, 45 and 70 of proteins were found to have significantly difference between the control group and three times of HPC group, the control and six times of HPC, and the three times of HPC and six times of HPC group. （3）Some endogenous metabolites such as phenylalanine, valine, proline, leucine and glu- tamine were increased, while ereatine was decreased, both in HPC brain and heart; in addition, y-aminobutyric acid was markedly decreased in brain. The sphingolipid metabolic pathways were noticed due to the low p-value and high pathway impact. Especially, the sphingolipid compound sphingomyelin, ceramide, glucosyleeramide, galactosylceramide and laetosylceramide were mapping in this metabolic pathway. Interestingly, these sphingolipid metabolites with olefinic bond in the long fatty chain were up-regulated, while those sphingolipids without olefinic bond were down-regulated. The functions of these differentially expressed genes mainly involved the cellular proces- ses including MAPK pathway, ion transport, neurotransmitter transport and neuropeptide signal pathway. The pro- tein levels related the ATP synthesis and citric acid cycle decreased while the proteins with the glycolysis and oxy- gen-binding increased. Glutathione, GNBP-1 and GPD1L were related to preventing hypoxic damage. The results indicated that C24：l-Cers played a critical role in HPC and had potential in endogenous protective mechanism. The combinations of the system omies data of the different molecules were sufficient to give a further understanding of the molecular pathways affected by HPC. Our data provided an important insight to reveal the protection mechanism of HPC.展开更多
Grinding is one of the most costly operations in the mechanical breaking and mining.Determination of the breakage characteristics and preconditioning is important to increase the grinding efficiency.Investigations of ...Grinding is one of the most costly operations in the mechanical breaking and mining.Determination of the breakage characteristics and preconditioning is important to increase the grinding efficiency.Investigations of the seismic,mechanical and breakage properties of iron oxides are very important parameters for investigating the rock fragmentation by blasting and comminution processes in iron ore mines.In this paper,at first,geomechanical and seismic properties of the oxide ores(magnetite and hematite)in the Chadormalu iron ore mine were studied.The results showed that the percentage of magnetite has a direct relationship with uniaxial compressive strength,tensile strength and P and S wave’s velocities and has an inverse relationship with Poisson ratio and porosity.Moreover,to study breakage and preconditioning characteristics in the iron ores,two samples with different magnetite percents were blasted by detonation cord.The results showed that with higher percentage of magnetite,the number of fractures induced by blasting increased.Bond work index and magnetite percent were investigated in the 430 blasts in the mine.This investigation not only confirmed the small scale blasting results,but also showed that increasing the magnetite percent up to 50%noticeably reduces Bond work index and energy consumption in the grinding process.Also,the relationship between muck pile fragmentation and magnetite percentage were studied for several blasts that had the same blast pattern parameters and similar geology conditions.These results also confirmed precedents conclusions regarding magnetite percent and preconditioning relationship.展开更多
OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be re...OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be related to alcohol in red wine.Our previous study demonstrated that ethanol ingestion 24 h prior to induction of cerebral ischemic/reperfusion(I/R)reduced delayed neuronal death(DND).Our most recent results supported a role for big Ca2+-sensitive K+channel(BKCa channel)activation in the neuroprotective effects of ethanol preconditioning(Et OH-PC)in global cerebral I/R.Therefore,we hypothesis that moderate Et OH-PC activates BKCa channel to protect brain damage induced by focal cerebral I/R.This project will utilize focal cerebral I/R animal model to explore the function of BKCa channel in Et OH-PC protection in vivo levels by means of pharmacological intervention such as BKCa channel opene(rNS11021,NS)and blocke(rpaxilline,PX).The results will provide theoretical evidence for neuroprotective effect of moderate alcohol preconditioning against ischemic stroke,and the conclusion will also bring to a concept that extrinsic moderate ethanol preconditioning may activate intrinsic protective mechanism in the brain.METHODS The SD rat were randomly divided into the following six groups(n=10):sham,I/R,Et OH-PC+I/R,NS11021-PC+I/R,paxilline+Et OH-PC+I/R,Paxilline+NS11021-PC+I/R.Both Et OH-PC and NS11021-PC(0.1mg·kg-1;ip)were induced 24 h before I/R.The volume of 95%ethanol to be instilled(inμL)was calculated as follows:〔body weight(g)×0.6〕+0.3.This volume of ethanol was mixed in 0.3 m L of sterile distilled water just before administration to the animals by gavage.The Paxilline(2.5 mg·kg-1;ip)was administered 10min beforeEt OH-PC and NS11021-PC.The right middle cerebral artery occlusion(MCAO)was produced by inversion of a 4-0-nylon filament.The filament was withdrawn 2 h after onset of MCAO and then reperfused.Neurological deficits and infarct volume were measured 24 h after I/R.Another 36 rats were randomly divided into 6 groups as above,6 in each group.DWI were performed 2h after ischemic and T2WI MRI were performed 24 h after I/R to observe the infarct volume of brain and the penumbra volume of brain in each group.Then rats were killed and detected the apoptotic cell death and degeneration of neurons.RESULTS Compared to I/R group,the neurological score(P<0.01),the infarct volume of brain(P<0.01),the infarct volume of ischemic penumbra(P<0.01),the percentage of apoptotic cell death(P<0.01)and the percentage of degenerative neurons(P<0.01)were significantly decreased after ethanol preconditioning,while these changes were reversed by paxilline(P<0.05);compared to I/R group,the neurological score(P<0.01),the infarct volume of brain(P<0.01),the infarct volume of ischemic penumbra(P<0.01),the percentage of apoptotic cell death(P<0.01)and the percentage of degenerative neurons(P<0.01)were significantly decreased after NS11021 preconditioning,while these changes were reversed by paxilline(P<0.05).CONCLUSION Our results show that moderate alcohol preconditioning activates BKCa channels to protect brain damage induced by focal cerebral I/R.展开更多
Objective To investigate the change of protein expression of lung tissue of rabbit after ischemic preconditioning(IP)and try to elucidate the potential protective mechanism of IP.Methods 12 domestic rabbits were rando...Objective To investigate the change of protein expression of lung tissue of rabbit after ischemic preconditioning(IP)and try to elucidate the potential protective mechanism of IP.Methods 12 domestic rabbits were randomly divided into group IP and group control(6 rabbits in each group).All the left lungs were afflicted by ische mia-reperfusion injury except that those in group IP were subject to IP prior to ischemic phase.2-DE was employed to separate the total protein of the lung tissue.PDQuest analysis software was used to distinguish the differently expressed protein spot.MALDI-TOF-MS and Mascot database searching were exploited to identify these proteins.Results 1)IP attenuated the ischemia-reperfusion lung injury.2)The proteomic analysis showed 35 target proteins,of which 17 were characterized such as phosphatidylinositol 3-kinase(PI3k)delta catalytic subunit.Conclusions 1)Proteomic is a promising tool to investigate the IP and ischemia-reperfusion lung injury.2)That IP inhibits inflammatory cascades through phosphatidylinositol 3-kinase signal transduction pathway may be one of its protective mechanism.展开更多
Aim This study is aimed to determine whether SPK2 （Sphingosine kinase-2） is involved in isoflurane preconditioning induced autophagy activation in primary cultured neurons. We also examined whether SPK2 pro- tects n...Aim This study is aimed to determine whether SPK2 （Sphingosine kinase-2） is involved in isoflurane preconditioning induced autophagy activation in primary cultured neurons. We also examined whether SPK2 pro- tects neurons from ischemic injury by activating autophagy, and explored the molecular mechanism of SPK2 contrib- uting to the autophagy activation in neurons. Methods Isoflurane preconditioning （ISO） and oxygen glucose dep- rivation （OGD） model was established in primary cultured murine cortical neurons. Neurons were transfected by siRNA to interfere SPK2 and Beclin 1, or lentivirus to overexpress SPK2. Protein expression of SPK2, LC3, and Beclinl were detected with immunofluorescence and Western blot analysis. The neurons were treated with lysosomal inhibitor ammonium chloride （NH4 C1） to test the autophagy flux. The protection of SPK2 on OGD/R induced neu- ronal death was detected with CCK-8 （cell counting kit-8） and LDH cytotoxicity assay kit. Autophagy inhibitor 3- MA （3-Methyladenine） was used to detect the protection of autophagy on SPK2 induced isehemie tolerance. Co-im- munoprecipitation was used to detect the interaction between Beclin 1 and Bel-2. Results In primary cultured neu- ISO enhanced SPK2 and LC3 immunofluorescenee. SPK2 siRNA inhibits LC3II upregulation induced by rons, ISO. Beclin 1 siRNA also inhibits LC3II upregulation induced by ISO. Lentivirus-indueed SPK2 overexpression in- creased LC3II/LC3I ratio and enhanced the autophagy flux in neurons. SPK2 overexpression also exerted neuropro- teetion against OGD model in cortical neurons, as evidenced by improvement of neuronal morphology, increased cellular viability and reduced LDH leakage, while 3-MA partly abolished the SPK2-induced neuroprotection. After SPK2 overexpression, Beclin 1 siRNA inhibited SPK2 induced LC3II upregulation, and the coimmunoprecipitation of Beclin 1 and Bcl-2 was reduced.. Conclusion ISO increases SPK2 and activates autophagy in neurons. SPK2 or Beclin 1 interference cancels ISO induced autophagy activation. SPK2 overexpression activates autophagy, and protects the neurons against ischemic injury. SPK2 may induce autophagy by disrupting Beclin 1/Bcl-2 interaction.展开更多
Objective To investigate the effects of sevoflurane preconditioning and postconditioning on electrophysiological characteristics of transient outward potassium channel(Ito)in rat ventricular myocytes.Methods Isolated ...Objective To investigate the effects of sevoflurane preconditioning and postconditioning on electrophysiological characteristics of transient outward potassium channel(Ito)in rat ventricular myocytes.Methods Isolated rat hearts were harvested and balanced with Langendorff perfusion system,then they were randomly assigned to one of the following 4 groups(n=10):(1)Time Control group(perfused with KH solution for 75 min);(2)Ischemia/reperfusion(I/R)group(perfused with KH solution for 20 min and then subjected to 25 min of global ischemia followed by 30 min of reperfusion with KH solution).展开更多
Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinui...Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.展开更多
The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and st...The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.展开更多
The grid equations in decomposed domain by parallel computation are soled, and a method of local orthogonalization to solve the large-scaled numerical computation is presented. It constructs preconditioned iteration m...The grid equations in decomposed domain by parallel computation are soled, and a method of local orthogonalization to solve the large-scaled numerical computation is presented. It constructs preconditioned iteration matrix by the combination of predigesting LU decomposition and local orthogonalization, and the convergence of solution is proved. Indicated from the example, this algorithm can increase the rate of computation efficiently and it is quite stable.展开更多
文摘Hypoxia preconditioning （HPC） is associated with many complicated pathophysiological and biochemical processes that integrated and regulated via molecular levels. HPC could protect cells, tissues, organs and systems from hypoxia injury, but up to date, the molecular mechanism still remained unclear. The acute and repetitive hy- poxia preconditioning model was constructed and the related parameters were observed. The high-throughput mi- croarray analysis and multiple bioinformatics were used to explore the differentially expressed genes in HPC mice brain and the related gene network, pathways and biological processes related to HPC. The 2D-DIGE coupled with MALDI-TOF/TOF-MS was performed to identify these proteins that were differentially expressed during HPC. The UPLC-HRMS based metabolomics method was utilized to explore the key endogenous metabolites and metabolic pathways related to HPC. The results showed that （1） 1175 differentially expressed genes in HPC mice brain were identified. Fourteen of these genes were the related hub genes for HPC, including Cacna2dl, Grin2a, Npylr, Mef2c, Epha4, Rxfpl, Chrm3, Pdela, Atp2b4, Glral, Idil , Fgfl, Grin2b and Cda. The change trends of all the detected genes by RT-PCR were consistent with the data of gene chips. There were 113 significant functions up- regulated and 138 significant functions down-regulated in HPC mice. （2） About 2100 proteins were revealed via the gel imaging and spot detection. 66, 45 and 70 of proteins were found to have significantly difference between the control group and three times of HPC group, the control and six times of HPC, and the three times of HPC and six times of HPC group. （3）Some endogenous metabolites such as phenylalanine, valine, proline, leucine and glu- tamine were increased, while ereatine was decreased, both in HPC brain and heart; in addition, y-aminobutyric acid was markedly decreased in brain. The sphingolipid metabolic pathways were noticed due to the low p-value and high pathway impact. Especially, the sphingolipid compound sphingomyelin, ceramide, glucosyleeramide, galactosylceramide and laetosylceramide were mapping in this metabolic pathway. Interestingly, these sphingolipid metabolites with olefinic bond in the long fatty chain were up-regulated, while those sphingolipids without olefinic bond were down-regulated. The functions of these differentially expressed genes mainly involved the cellular proces- ses including MAPK pathway, ion transport, neurotransmitter transport and neuropeptide signal pathway. The pro- tein levels related the ATP synthesis and citric acid cycle decreased while the proteins with the glycolysis and oxy- gen-binding increased. Glutathione, GNBP-1 and GPD1L were related to preventing hypoxic damage. The results indicated that C24：l-Cers played a critical role in HPC and had potential in endogenous protective mechanism. The combinations of the system omies data of the different molecules were sufficient to give a further understanding of the molecular pathways affected by HPC. Our data provided an important insight to reveal the protection mechanism of HPC.
文摘Grinding is one of the most costly operations in the mechanical breaking and mining.Determination of the breakage characteristics and preconditioning is important to increase the grinding efficiency.Investigations of the seismic,mechanical and breakage properties of iron oxides are very important parameters for investigating the rock fragmentation by blasting and comminution processes in iron ore mines.In this paper,at first,geomechanical and seismic properties of the oxide ores(magnetite and hematite)in the Chadormalu iron ore mine were studied.The results showed that the percentage of magnetite has a direct relationship with uniaxial compressive strength,tensile strength and P and S wave’s velocities and has an inverse relationship with Poisson ratio and porosity.Moreover,to study breakage and preconditioning characteristics in the iron ores,two samples with different magnetite percents were blasted by detonation cord.The results showed that with higher percentage of magnetite,the number of fractures induced by blasting increased.Bond work index and magnetite percent were investigated in the 430 blasts in the mine.This investigation not only confirmed the small scale blasting results,but also showed that increasing the magnetite percent up to 50%noticeably reduces Bond work index and energy consumption in the grinding process.Also,the relationship between muck pile fragmentation and magnetite percentage were studied for several blasts that had the same blast pattern parameters and similar geology conditions.These results also confirmed precedents conclusions regarding magnetite percent and preconditioning relationship.
基金The project supported by NSFC(81171079,81271312)
文摘OBJCETIVE Epidemiologic studies have demonstrated that consumption of moderate amounts of red wine is associated with significant reductions in incidences of cardiovascular and cerebrovascular diseases,which may be related to alcohol in red wine.Our previous study demonstrated that ethanol ingestion 24 h prior to induction of cerebral ischemic/reperfusion(I/R)reduced delayed neuronal death(DND).Our most recent results supported a role for big Ca2+-sensitive K+channel(BKCa channel)activation in the neuroprotective effects of ethanol preconditioning(Et OH-PC)in global cerebral I/R.Therefore,we hypothesis that moderate Et OH-PC activates BKCa channel to protect brain damage induced by focal cerebral I/R.This project will utilize focal cerebral I/R animal model to explore the function of BKCa channel in Et OH-PC protection in vivo levels by means of pharmacological intervention such as BKCa channel opene(rNS11021,NS)and blocke(rpaxilline,PX).The results will provide theoretical evidence for neuroprotective effect of moderate alcohol preconditioning against ischemic stroke,and the conclusion will also bring to a concept that extrinsic moderate ethanol preconditioning may activate intrinsic protective mechanism in the brain.METHODS The SD rat were randomly divided into the following six groups(n=10):sham,I/R,Et OH-PC+I/R,NS11021-PC+I/R,paxilline+Et OH-PC+I/R,Paxilline+NS11021-PC+I/R.Both Et OH-PC and NS11021-PC(0.1mg·kg-1;ip)were induced 24 h before I/R.The volume of 95%ethanol to be instilled(inμL)was calculated as follows:〔body weight(g)×0.6〕+0.3.This volume of ethanol was mixed in 0.3 m L of sterile distilled water just before administration to the animals by gavage.The Paxilline(2.5 mg·kg-1;ip)was administered 10min beforeEt OH-PC and NS11021-PC.The right middle cerebral artery occlusion(MCAO)was produced by inversion of a 4-0-nylon filament.The filament was withdrawn 2 h after onset of MCAO and then reperfused.Neurological deficits and infarct volume were measured 24 h after I/R.Another 36 rats were randomly divided into 6 groups as above,6 in each group.DWI were performed 2h after ischemic and T2WI MRI were performed 24 h after I/R to observe the infarct volume of brain and the penumbra volume of brain in each group.Then rats were killed and detected the apoptotic cell death and degeneration of neurons.RESULTS Compared to I/R group,the neurological score(P<0.01),the infarct volume of brain(P<0.01),the infarct volume of ischemic penumbra(P<0.01),the percentage of apoptotic cell death(P<0.01)and the percentage of degenerative neurons(P<0.01)were significantly decreased after ethanol preconditioning,while these changes were reversed by paxilline(P<0.05);compared to I/R group,the neurological score(P<0.01),the infarct volume of brain(P<0.01),the infarct volume of ischemic penumbra(P<0.01),the percentage of apoptotic cell death(P<0.01)and the percentage of degenerative neurons(P<0.01)were significantly decreased after NS11021 preconditioning,while these changes were reversed by paxilline(P<0.05).CONCLUSION Our results show that moderate alcohol preconditioning activates BKCa channels to protect brain damage induced by focal cerebral I/R.
基金Project(2004036433)supported by the Postdoctoral Science Foundation of Chinaproject(B2004024)supported by theScience Foundation of Public Health Bureau of Hunan Province
文摘Objective To investigate the change of protein expression of lung tissue of rabbit after ischemic preconditioning(IP)and try to elucidate the potential protective mechanism of IP.Methods 12 domestic rabbits were randomly divided into group IP and group control(6 rabbits in each group).All the left lungs were afflicted by ische mia-reperfusion injury except that those in group IP were subject to IP prior to ischemic phase.2-DE was employed to separate the total protein of the lung tissue.PDQuest analysis software was used to distinguish the differently expressed protein spot.MALDI-TOF-MS and Mascot database searching were exploited to identify these proteins.Results 1)IP attenuated the ischemia-reperfusion lung injury.2)The proteomic analysis showed 35 target proteins,of which 17 were characterized such as phosphatidylinositol 3-kinase(PI3k)delta catalytic subunit.Conclusions 1)Proteomic is a promising tool to investigate the IP and ischemia-reperfusion lung injury.2)That IP inhibits inflammatory cascades through phosphatidylinositol 3-kinase signal transduction pathway may be one of its protective mechanism.
文摘Aim This study is aimed to determine whether SPK2 （Sphingosine kinase-2） is involved in isoflurane preconditioning induced autophagy activation in primary cultured neurons. We also examined whether SPK2 pro- tects neurons from ischemic injury by activating autophagy, and explored the molecular mechanism of SPK2 contrib- uting to the autophagy activation in neurons. Methods Isoflurane preconditioning （ISO） and oxygen glucose dep- rivation （OGD） model was established in primary cultured murine cortical neurons. Neurons were transfected by siRNA to interfere SPK2 and Beclin 1, or lentivirus to overexpress SPK2. Protein expression of SPK2, LC3, and Beclinl were detected with immunofluorescence and Western blot analysis. The neurons were treated with lysosomal inhibitor ammonium chloride （NH4 C1） to test the autophagy flux. The protection of SPK2 on OGD/R induced neu- ronal death was detected with CCK-8 （cell counting kit-8） and LDH cytotoxicity assay kit. Autophagy inhibitor 3- MA （3-Methyladenine） was used to detect the protection of autophagy on SPK2 induced isehemie tolerance. Co-im- munoprecipitation was used to detect the interaction between Beclin 1 and Bel-2. Results In primary cultured neu- ISO enhanced SPK2 and LC3 immunofluorescenee. SPK2 siRNA inhibits LC3II upregulation induced by rons, ISO. Beclin 1 siRNA also inhibits LC3II upregulation induced by ISO. Lentivirus-indueed SPK2 overexpression in- creased LC3II/LC3I ratio and enhanced the autophagy flux in neurons. SPK2 overexpression also exerted neuropro- teetion against OGD model in cortical neurons, as evidenced by improvement of neuronal morphology, increased cellular viability and reduced LDH leakage, while 3-MA partly abolished the SPK2-induced neuroprotection. After SPK2 overexpression, Beclin 1 siRNA inhibited SPK2 induced LC3II upregulation, and the coimmunoprecipitation of Beclin 1 and Bcl-2 was reduced.. Conclusion ISO increases SPK2 and activates autophagy in neurons. SPK2 or Beclin 1 interference cancels ISO induced autophagy activation. SPK2 overexpression activates autophagy, and protects the neurons against ischemic injury. SPK2 may induce autophagy by disrupting Beclin 1/Bcl-2 interaction.
文摘Objective To investigate the effects of sevoflurane preconditioning and postconditioning on electrophysiological characteristics of transient outward potassium channel(Ito)in rat ventricular myocytes.Methods Isolated rat hearts were harvested and balanced with Langendorff perfusion system,then they were randomly assigned to one of the following 4 groups(n=10):(1)Time Control group(perfused with KH solution for 75 min);(2)Ischemia/reperfusion(I/R)group(perfused with KH solution for 20 min and then subjected to 25 min of global ischemia followed by 30 min of reperfusion with KH solution).
基金Projects(41174061,41374120)supported by the National Natural Science Foundation of China
文摘Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.
基金Projects(40974077,41164004)supported by the National Natural Science Foundation of ChinaProject(2007AA06Z134)supported by the National High Technology Research and Development Program of China+2 种基金Projects(2011GXNSFA018003,0832263)supported by the Natural Science Foundation of Guangxi Province,ChinaProject supported by Program for Excellent Talents in Guangxi Higher Education Institution,ChinaProject supported by the Foundation of Guilin University of Technology,China
文摘The strategies that minimize the overall solution time of multiple linear systems in 3D finite element method (FEM) modeling of direct current (DC) resistivity were discussed. A global stiff matrix is assembled and stored in two parts separately. One part is associated with the volume integral and the other is associated with the subsurface boundary integral. The equivalent multiple linear systems with closer right-hand sides than the original systems were constructed. A recycling Krylov subspace technique was employed to solve the multiple linear systems. The solution of the seed system was used as an initial guess for the subsequent systems. The results of two numerical experiments show that the improved algorithm reduces the iterations and CPU time by almost 50%, compared with the classical preconditioned conjugate gradient method.
文摘The grid equations in decomposed domain by parallel computation are soled, and a method of local orthogonalization to solve the large-scaled numerical computation is presented. It constructs preconditioned iteration matrix by the combination of predigesting LU decomposition and local orthogonalization, and the convergence of solution is proved. Indicated from the example, this algorithm can increase the rate of computation efficiently and it is quite stable.
