How to extract optimal composite attributes from a variety of conventional seismic attributes to detect reservoir features is a reservoir predication key,which is usually solved by reducing dimensionality.Principle co...How to extract optimal composite attributes from a variety of conventional seismic attributes to detect reservoir features is a reservoir predication key,which is usually solved by reducing dimensionality.Principle component analysis（PCA） is the most widely-used linear dimensionality reduction method at present.However,the relationships between seismic attributes and reservoir features are non-linear,so seismic attribute dimensionality reduction based on linear transforms can＇t solve non-linear problems well,reducing reservoir prediction precision.As a new non-linear learning method,manifold learning supplies a new method for seismic attribute analysis.It can discover the intrinsic features and rules hidden in the data by computing low-dimensional,neighborhood-preserving embeddings of high-dimensional inputs.In this paper,we try to extract seismic attributes using locally linear embedding（LLE）,realizing inter-horizon attributes dimensionality reduction of 3D seismic data first and discuss the optimization of its key parameters.Combining model analysis and case studies,we compare the dimensionality reduction and clustering effects of LLE and PCA,both of which indicate that LLE can retain the intrinsic structure of the inputs.The composite attributes and clustering results based on LLE better characterize the distribution of sedimentary facies,reservoir,and even reservoir fluids.展开更多
Debris flows consist of grains of various sizes ranging from 10^(-6) m ～1 m. Field observations in the Jiangjia Gully (JJG) and other sites throughout China indicate that the grain size distribution of sediment in de...Debris flows consist of grains of various sizes ranging from 10^(-6) m ～1 m. Field observations in the Jiangjia Gully (JJG) and other sites throughout China indicate that the grain size distribution of sediment in debris flows can be characterized by an exponential function fit to the cumulative distribution. The exponent value for the function varies by location and may be useful in distinguishing between debris flows from different valleys. For example, minimum values and ranges of the exponent are associated with the high frequency of debris flows in the JJG. Furthermore, the distribution presents piecewise fractality (i.e. scaling laws hold in various ranges of the grain size) and we propose that the fractal structure determines the matrix and that the fractal dimension plays a crucial role in material exchange between a debris flow and the substrate it flows over. Finally, the empirical data support an exponential relation between grain composition and non-dimensional shear stress for the critical state of the channel. Overall we propose a material-determinism approach to studying debris flows which contrasts with the enviro-determinism that has dominated much recent work in this field.展开更多
Objective.To assess the feature of pulmonary blood flow distribution after total cavopulmonary connection(TCPC)of different types,and to provide the selection of the best type.Methods. Thirty-two consecutive survival ...Objective.To assess the feature of pulmonary blood flow distribution after total cavopulmonary connection(TCPC)of different types,and to provide the selection of the best type.Methods. Thirty-two consecutive survival patients after TCPC underwent radionuclide lung perfusion imaging. According to the radionuclide counts in the left and right lungs,analyses of the distribution of blood flow from superior venous cava(SVC) and inferior venous cava(IVC)and the whole pulmonary blood flow in both lungs were made. All patients were divided into 4 groups by the the anastomosis between IVC and pulmonary artery.Results. GroupⅠ:The flow ratio of the IVC to left lung was greater than that to the right lung,P≤0.01;the flow ratio of the SVC to right lung was greater than that to the left lung,P≤0.01;and the whole pulmonary blood flow went dominantly to the left lung,P≤0.05,which is not in line with physiological distribution. GroupⅡ:the flows from the SVC and IVC were mixed in the middle of the junction and ran evenly into the right and left lungs,the whole pulmonary blood flow went to both lungs,P≥0.05. Group Ⅲ:the flow ratio of the SVC to both lungs were the same,P≥0.05,and major part from IVC went to the right lung,P≤0.01;the pulmonary blood flow go dominantly to the right lung,P≤0.05,which is in accord with physiological distribution. Group Ⅳ:the flows from the right SVC went to right lung by 100%,P≤0.01,and that from the left SVC went to left lung by 100% too,P≤0.01;the flows from IVC went dominantly to the left lung,with little part to the right lung ,P≤0.05.Conclusions. Different types of TCPC can result in different pulmonary blood distributions. The best flow distribution between the left and right lungs can be obtained by an offset of the IVC anastomosis toward the RPA with widening anastomosis for the patients without persist left superior venous cava(PLSVC).展开更多
Objective. To review our preliminary experience and evaluate our early results of a combined intraoperative iliac angioplasty and stenting with infrainguinal revascularization in multilevel atherosclerotic occlusive d...Objective. To review our preliminary experience and evaluate our early results of a combined intraoperative iliac angioplasty and stenting with infrainguinal revascularization in multilevel atherosclerotic occlusive disease. Methods. From July 1999 to April 2000, intraoperative iliac angioplasty and stenting combined with simultaneous femoro- popliteal bypass were performed on 12 lower extremities of 10 patients suffering from multilevel atherosclerotic occlusive disease. There were 8 men and 2 women, average 72 years. The indications for procedures included disabling claudication in 3 and rest pain in 7 patients. Results. Eleven iliac angioplasty and stent procedures combined with simultaneous 9 femoro- popliteal bypass and 3 femoro- femoral- popliteal bypass were performed in 12 limbs of 10 patients. Angioplasty and stent placement was technically successful in all patients. One contralateral femoral- popliteal bypass was failure after femorofemoral- popliteal bypass. There were no additional instances of procedural or postoperative morbidity or mortali- ty. Mean follow- up was 5 months (range 1～ 10 months). During the follow- up period, one femoro- infrapopliteal graft became occluded after 7 months and above- knee amputation was required. The cumulative primary patency rate of stented iliac arteries, femoro- femoral bypass grafts and femoro- popliteal bypass grafts were 100％ (11/11), 100％ (3/3) and 90.9％ (10/11) in the follow- up period, respectively. The amputation rate was 8.3％ (1/12). Conclusions. Intraoperative iliac artery PTA and stent placement can be safely and effectively performed simultaneously with infrainguinal revascularization for multilevel atherosclerotic occlusive disease by skilled vascular surgeon, using a portable C arm fluoroscopy in the operating room. Furthermore, iliac artery PTA and stenting was valuable adjunct to distal bypass either to improve inflow and outflow, or to reduce the extent of traditional surgical intervention, and also, any angioplasty and stenting- related complications can be immediately corrected as well.展开更多
The purpose of this paper is looking for associations between environmental factors and morphological parameters in tambaqui （Piaractus brachypomus） individuals to differentiate this species in lentic environments ...The purpose of this paper is looking for associations between environmental factors and morphological parameters in tambaqui （Piaractus brachypomus） individuals to differentiate this species in lentic environments （lake） and lotic （river）. In this, regard studied 30 specimens, 15 from lentic environment （lake） and 15 from lotic （river）. Also, on right profile of these 25 morphometric variables were measured. On data matrix a PCA （principal components analysis） based on morphometric correlations matrix, which was defined in the new morphologic space of these specimens （3 principal components） which explain 73.23% of variability. Fish projection in first two principal components showed a morphological differentiation between two environments （lentic and lotic）, with variables as, horizontal eye diameter, length maxilla, suggesting greater response of these fish in lotic environment by their adaptation to light conditions, predators threat and food distribution. Finally, in lotic environment these fish have thinner caudal peduncle, indicating greater plasticity, namely stylized fish.展开更多
The authors establish some uniform estimates for the distance to halfway points of minimalgeodesics in terms of the distantce to end points on some types of Riemannian manifolds, andthen prove some theorems about the ...The authors establish some uniform estimates for the distance to halfway points of minimalgeodesics in terms of the distantce to end points on some types of Riemannian manifolds, andthen prove some theorems about the finite generation of fundamental group of Riemannianmanifold with nonnegative Ricci curvature, which support the famous Milnor conjecture.展开更多
We conjecture a formula for the generating function of genus one Gromov-Witten invariants of the local Calabi-Yau manifolds which are the total spaces of splitting bundles over projective spaces. We prove this conject...We conjecture a formula for the generating function of genus one Gromov-Witten invariants of the local Calabi-Yau manifolds which are the total spaces of splitting bundles over projective spaces. We prove this conjecture in several special cases, and assuming the validity of our conjecture we check the integrality of genus one Bogomol'nyi-Prasad-Sommerfield(BPS) numbers of local Calabi-Yau 5-folds defined by Klemm and Pandharipande.展开更多
基金National Key Science & Technology Special Projects(Grant No.2008ZX05000-004)CNPC Projects(Grant No.2008E-0610-10).
文摘How to extract optimal composite attributes from a variety of conventional seismic attributes to detect reservoir features is a reservoir predication key,which is usually solved by reducing dimensionality.Principle component analysis（PCA） is the most widely-used linear dimensionality reduction method at present.However,the relationships between seismic attributes and reservoir features are non-linear,so seismic attribute dimensionality reduction based on linear transforms can＇t solve non-linear problems well,reducing reservoir prediction precision.As a new non-linear learning method,manifold learning supplies a new method for seismic attribute analysis.It can discover the intrinsic features and rules hidden in the data by computing low-dimensional,neighborhood-preserving embeddings of high-dimensional inputs.In this paper,we try to extract seismic attributes using locally linear embedding（LLE）,realizing inter-horizon attributes dimensionality reduction of 3D seismic data first and discuss the optimization of its key parameters.Combining model analysis and case studies,we compare the dimensionality reduction and clustering effects of LLE and PCA,both of which indicate that LLE can retain the intrinsic structure of the inputs.The composite attributes and clustering results based on LLE better characterize the distribution of sedimentary facies,reservoir,and even reservoir fluids.
基金This work is supported by National Science Foundation Grant No. 40671025 and 40501008；also by the Knowledge Innovation Project of Chinese Academy of Sciences, KZCX3-SW-352；the Frontier Project of Institute of Mountain Hazard and Environment, CAS, No. C3-200307. Special gratitude goes to Dr. He Yiping for field data for the JJG debris flow.
文摘Debris flows consist of grains of various sizes ranging from 10^(-6) m ～1 m. Field observations in the Jiangjia Gully (JJG) and other sites throughout China indicate that the grain size distribution of sediment in debris flows can be characterized by an exponential function fit to the cumulative distribution. The exponent value for the function varies by location and may be useful in distinguishing between debris flows from different valleys. For example, minimum values and ranges of the exponent are associated with the high frequency of debris flows in the JJG. Furthermore, the distribution presents piecewise fractality (i.e. scaling laws hold in various ranges of the grain size) and we propose that the fractal structure determines the matrix and that the fractal dimension plays a crucial role in material exchange between a debris flow and the substrate it flows over. Finally, the empirical data support an exponential relation between grain composition and non-dimensional shear stress for the critical state of the channel. Overall we propose a material-determinism approach to studying debris flows which contrasts with the enviro-determinism that has dominated much recent work in this field.
文摘Objective.To assess the feature of pulmonary blood flow distribution after total cavopulmonary connection(TCPC)of different types,and to provide the selection of the best type.Methods. Thirty-two consecutive survival patients after TCPC underwent radionuclide lung perfusion imaging. According to the radionuclide counts in the left and right lungs,analyses of the distribution of blood flow from superior venous cava(SVC) and inferior venous cava(IVC)and the whole pulmonary blood flow in both lungs were made. All patients were divided into 4 groups by the the anastomosis between IVC and pulmonary artery.Results. GroupⅠ:The flow ratio of the IVC to left lung was greater than that to the right lung,P≤0.01;the flow ratio of the SVC to right lung was greater than that to the left lung,P≤0.01;and the whole pulmonary blood flow went dominantly to the left lung,P≤0.05,which is not in line with physiological distribution. GroupⅡ:the flows from the SVC and IVC were mixed in the middle of the junction and ran evenly into the right and left lungs,the whole pulmonary blood flow went to both lungs,P≥0.05. Group Ⅲ:the flow ratio of the SVC to both lungs were the same,P≥0.05,and major part from IVC went to the right lung,P≤0.01;the pulmonary blood flow go dominantly to the right lung,P≤0.05,which is in accord with physiological distribution. Group Ⅳ:the flows from the right SVC went to right lung by 100%,P≤0.01,and that from the left SVC went to left lung by 100% too,P≤0.01;the flows from IVC went dominantly to the left lung,with little part to the right lung ,P≤0.05.Conclusions. Different types of TCPC can result in different pulmonary blood distributions. The best flow distribution between the left and right lungs can be obtained by an offset of the IVC anastomosis toward the RPA with widening anastomosis for the patients without persist left superior venous cava(PLSVC).
文摘Objective. To review our preliminary experience and evaluate our early results of a combined intraoperative iliac angioplasty and stenting with infrainguinal revascularization in multilevel atherosclerotic occlusive disease. Methods. From July 1999 to April 2000, intraoperative iliac angioplasty and stenting combined with simultaneous femoro- popliteal bypass were performed on 12 lower extremities of 10 patients suffering from multilevel atherosclerotic occlusive disease. There were 8 men and 2 women, average 72 years. The indications for procedures included disabling claudication in 3 and rest pain in 7 patients. Results. Eleven iliac angioplasty and stent procedures combined with simultaneous 9 femoro- popliteal bypass and 3 femoro- femoral- popliteal bypass were performed in 12 limbs of 10 patients. Angioplasty and stent placement was technically successful in all patients. One contralateral femoral- popliteal bypass was failure after femorofemoral- popliteal bypass. There were no additional instances of procedural or postoperative morbidity or mortali- ty. Mean follow- up was 5 months (range 1～ 10 months). During the follow- up period, one femoro- infrapopliteal graft became occluded after 7 months and above- knee amputation was required. The cumulative primary patency rate of stented iliac arteries, femoro- femoral bypass grafts and femoro- popliteal bypass grafts were 100％ (11/11), 100％ (3/3) and 90.9％ (10/11) in the follow- up period, respectively. The amputation rate was 8.3％ (1/12). Conclusions. Intraoperative iliac artery PTA and stent placement can be safely and effectively performed simultaneously with infrainguinal revascularization for multilevel atherosclerotic occlusive disease by skilled vascular surgeon, using a portable C arm fluoroscopy in the operating room. Furthermore, iliac artery PTA and stenting was valuable adjunct to distal bypass either to improve inflow and outflow, or to reduce the extent of traditional surgical intervention, and also, any angioplasty and stenting- related complications can be immediately corrected as well.
文摘The purpose of this paper is looking for associations between environmental factors and morphological parameters in tambaqui （Piaractus brachypomus） individuals to differentiate this species in lentic environments （lake） and lotic （river）. In this, regard studied 30 specimens, 15 from lentic environment （lake） and 15 from lotic （river）. Also, on right profile of these 25 morphometric variables were measured. On data matrix a PCA （principal components analysis） based on morphometric correlations matrix, which was defined in the new morphologic space of these specimens （3 principal components） which explain 73.23% of variability. Fish projection in first two principal components showed a morphological differentiation between two environments （lentic and lotic）, with variables as, horizontal eye diameter, length maxilla, suggesting greater response of these fish in lotic environment by their adaptation to light conditions, predators threat and food distribution. Finally, in lotic environment these fish have thinner caudal peduncle, indicating greater plasticity, namely stylized fish.
基金the National Natural Science Foundation of China(No.19971081).
文摘The authors establish some uniform estimates for the distance to halfway points of minimalgeodesics in terms of the distantce to end points on some types of Riemannian manifolds, andthen prove some theorems about the finite generation of fundamental group of Riemannianmanifold with nonnegative Ricci curvature, which support the famous Milnor conjecture.
文摘We conjecture a formula for the generating function of genus one Gromov-Witten invariants of the local Calabi-Yau manifolds which are the total spaces of splitting bundles over projective spaces. We prove this conjecture in several special cases, and assuming the validity of our conjecture we check the integrality of genus one Bogomol'nyi-Prasad-Sommerfield(BPS) numbers of local Calabi-Yau 5-folds defined by Klemm and Pandharipande.
