The marching cube algorithm is currently one of the most popular three-dimensional(3D)reconstruction surface rendering algorithms.It forms cube voxels based on an input image and then uses 15 basic topological configu...The marching cube algorithm is currently one of the most popular three-dimensional(3D)reconstruction surface rendering algorithms.It forms cube voxels based on an input image and then uses 15 basic topological configurations to extract isosurfaces from the voxels.The algorithm processes each cube voxel in a traversal-based manner,but it does not consider the relationship between the isosurfaces in adjacent cubes.Owing to ambiguity,the final reconstructed model may have holes.In this paper,we propose a marching cube algorithm based on edge growth.The algorithm first extracts seed triangles,grows these seed triangles,and then reconstructs the entire 3D model.According to the position of the growth edge,we propose 17 topological configurations with isosurfaces.The reconstruction results showed that the algorithm can reconstruct the 3D model well.When only the main contour of the 3D model is required,the algorithm performs well.In addition,when there are multiple scattered parts in the data,the algorithm can extract only the 3D contours of the parts connected to the seed by setting the region selected based on the seed.展开更多
A parity check matrix construction method for constructing a low-density parity-check （LDPC） codes over GF（q） （q〉2） based on the modified progressive edge growth （PEG） algorithm is introduced. First, the nonz...A parity check matrix construction method for constructing a low-density parity-check （LDPC） codes over GF（q） （q〉2） based on the modified progressive edge growth （PEG） algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF（q）-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.展开更多
Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distribut...Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distributed at the edge of faults,in poor sand bodies,and in insufficiently injected and produced areas.Therefore,the edge of faults is a major target for remaining oil enrichment and potential tapping.Based on the dynamic change of production from development wells determined by the injection-recovery relationship at the edge of faults,we analyzed the control of structural features of faults on remaining oil enrichment at the edge.Our results show that the macroscopic structural features and their geometric relationship with sand bodies controlled remaining oil enrichment zones like the edges of NNE-striking faults,the footwalls of antithetic faults,the hard linkage segments（two faults had linked together with each other to form a bigger through-going fault）,the tips of faults,and the oblique anticlines of soft linkages.Fault edges formed two types of forward microamplitude structures：（1） the tilted uplift of footwalls controlled by inverse fault sections and（2） the hanging-wall horizontal anticlines controlled by synthetic fault points.The remaining oil distribution was controlled by microamplitude structures.Consequently,such zones as the tilted uplift of the footwall of the NNW-striking antithetic faults with a fault throw larger than 40 m,the hard linkage segments,the tips of faults,and the oblique anticlines of soft linkage were favorable for tapping the remaining oil potential.Multi-target directional drilling was used for remaining oil development at fault edges.Reasonable fault spacing was determined on the basis of fault combinations and width of the shattered zone.Well core and log data revealed that the width of the shattered zone on the side of the fault core was less than 15 m in general;therefore,the distance from a fault to the development target should be larger than 15 m.Vertically segmented growth faults should take the separation of the lateral overlap of faults into account.Therefore,the safe distance of remaining oil well deployment at the fault edge should be larger than the sum of the width of shattered zone in faults and the separation of growth faults by vertical segmentation.展开更多
Potassium lithium niobate single crystal with a dimension of 20mm×15mm×30mm was grown by EFG technique in our laboratory.Compared with Czochralski method for the growth of KLN crystals,EFG technique possesse...Potassium lithium niobate single crystal with a dimension of 20mm×15mm×30mm was grown by EFG technique in our laboratory.Compared with Czochralski method for the growth of KLN crystals,EFG technique possesses the following merits.Crack of crystals can be weakened during the lowering of temperature and the crystals free of crack can be obtained.The crystals have no rotation,the growth striation caused by the rotation of the crystals can be eliminated.With action of capillary from a die hole,the convective effect of melt at solid liquid interface can be reduced,therefore the homogeneity of crystals is better than that of crystals obtained by Czochralski method.The growth striation parallels each other and is perpendicular to the growth direction,so the good blue SHG can be obtained when ground wave goes through the KLN crystals.Since capillary force does not fully counteract the convective effect,the inhomogeneity of crystals can’t completely be eliminated.The low SHG conversion efficiency of KLN crystals is mainly caused by inhomogeneneity of crystals.For the growth of incongruent melting crystals,the growth rate is limited by the rejection of impurity,this also makes homogeneity of composition become bad.In the growth of KLN crystals by EFG technique,the fluctuation of the temperature at solid liquid interface should be enough small,and the film thickness of melt should be proper.Too thick film of melt makes the process of crystal growth unstable;too thin film of melt can lead to the constitutional supercooling.展开更多
This work describes investigation of radiation dosimetry characteristics of magnesium （Mg） doped lithium fluoride （LiF） crystals co-doped with different concentrations of dysprosium （Dy）. These crystals were gro...This work describes investigation of radiation dosimetry characteristics of magnesium （Mg） doped lithium fluoride （LiF） crystals co-doped with different concentrations of dysprosium （Dy）. These crystals were grown by edge defined film fed crystal growth （EFG） tech- nique. Thermoluminescence （TL） measurements were made on as grown （AG） and annealed （AN） crystals after they were irradiated with a gamma dose of 15 Gy. The influence and advantage of optimized Dy^3＋ concentration in enhancing the thermoluminescence （TL） properties of LiF：Mg samples were discussed. The normalized peak height of the annealed crystals was nearly 3 times that of the as grown crystals for the particular concentration samples irradiated with Co6~ gamma source showed linearity up to 10 Gy. Thermoluminescence signal observed over a period of one month showed negligible fading. Thermoluminescence glow curve structure of optimized phosphor remained stable for higher doses of gamma rays of 103 Gy. Glow curve was analyzed using computer glow curve deconvolution （CGCD） method and trapping parame- ters were calculated.展开更多
基金the NSFC(61972117)the Natural Science Foundation of Heilongjiang Province of China(ZD2019E007)。
文摘The marching cube algorithm is currently one of the most popular three-dimensional(3D)reconstruction surface rendering algorithms.It forms cube voxels based on an input image and then uses 15 basic topological configurations to extract isosurfaces from the voxels.The algorithm processes each cube voxel in a traversal-based manner,but it does not consider the relationship between the isosurfaces in adjacent cubes.Owing to ambiguity,the final reconstructed model may have holes.In this paper,we propose a marching cube algorithm based on edge growth.The algorithm first extracts seed triangles,grows these seed triangles,and then reconstructs the entire 3D model.According to the position of the growth edge,we propose 17 topological configurations with isosurfaces.The reconstruction results showed that the algorithm can reconstruct the 3D model well.When only the main contour of the 3D model is required,the algorithm performs well.In addition,when there are multiple scattered parts in the data,the algorithm can extract only the 3D contours of the parts connected to the seed by setting the region selected based on the seed.
基金supported by the National Natural Science Foundation of China (60672087)
文摘A parity check matrix construction method for constructing a low-density parity-check （LDPC） codes over GF（q） （q〉2） based on the modified progressive edge growth （PEG） algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF（q）-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.
基金financial support from the Natural Science Foundation of China (Grant No. 41272151, 41472126)the Natural Science Foundation for Distinguished Young Scholars of Heilongjiang Province, China (Grant No. JC201304)+1 种基金the Joint Funds of the National Natural Science Foundation of China (Grant No. U1562214)the Program for Huabei Oilfield (Grant No. HBYT-CY5-2015-JS-127)
文摘Most major oil zones in the Daqing Oilfield have reached a later,high water cut stage,but oil recovery is still only approximately 35%,and 50%of reserves remain to be recovered.The remaining oil is primarily distributed at the edge of faults,in poor sand bodies,and in insufficiently injected and produced areas.Therefore,the edge of faults is a major target for remaining oil enrichment and potential tapping.Based on the dynamic change of production from development wells determined by the injection-recovery relationship at the edge of faults,we analyzed the control of structural features of faults on remaining oil enrichment at the edge.Our results show that the macroscopic structural features and their geometric relationship with sand bodies controlled remaining oil enrichment zones like the edges of NNE-striking faults,the footwalls of antithetic faults,the hard linkage segments（two faults had linked together with each other to form a bigger through-going fault）,the tips of faults,and the oblique anticlines of soft linkages.Fault edges formed two types of forward microamplitude structures：（1） the tilted uplift of footwalls controlled by inverse fault sections and（2） the hanging-wall horizontal anticlines controlled by synthetic fault points.The remaining oil distribution was controlled by microamplitude structures.Consequently,such zones as the tilted uplift of the footwall of the NNW-striking antithetic faults with a fault throw larger than 40 m,the hard linkage segments,the tips of faults,and the oblique anticlines of soft linkage were favorable for tapping the remaining oil potential.Multi-target directional drilling was used for remaining oil development at fault edges.Reasonable fault spacing was determined on the basis of fault combinations and width of the shattered zone.Well core and log data revealed that the width of the shattered zone on the side of the fault core was less than 15 m in general;therefore,the distance from a fault to the development target should be larger than 15 m.Vertically segmented growth faults should take the separation of the lateral overlap of faults into account.Therefore,the safe distance of remaining oil well deployment at the fault edge should be larger than the sum of the width of shattered zone in faults and the separation of growth faults by vertical segmentation.
文摘Potassium lithium niobate single crystal with a dimension of 20mm×15mm×30mm was grown by EFG technique in our laboratory.Compared with Czochralski method for the growth of KLN crystals,EFG technique possesses the following merits.Crack of crystals can be weakened during the lowering of temperature and the crystals free of crack can be obtained.The crystals have no rotation,the growth striation caused by the rotation of the crystals can be eliminated.With action of capillary from a die hole,the convective effect of melt at solid liquid interface can be reduced,therefore the homogeneity of crystals is better than that of crystals obtained by Czochralski method.The growth striation parallels each other and is perpendicular to the growth direction,so the good blue SHG can be obtained when ground wave goes through the KLN crystals.Since capillary force does not fully counteract the convective effect,the inhomogeneity of crystals can’t completely be eliminated.The low SHG conversion efficiency of KLN crystals is mainly caused by inhomogeneneity of crystals.For the growth of incongruent melting crystals,the growth rate is limited by the rejection of impurity,this also makes homogeneity of composition become bad.In the growth of KLN crystals by EFG technique,the fluctuation of the temperature at solid liquid interface should be enough small,and the film thickness of melt should be proper.Too thick film of melt makes the process of crystal growth unstable;too thin film of melt can lead to the constitutional supercooling.
基金Project supported by the Department of Science & Technology Project (SR/NM/NAT-02-2007)
文摘This work describes investigation of radiation dosimetry characteristics of magnesium （Mg） doped lithium fluoride （LiF） crystals co-doped with different concentrations of dysprosium （Dy）. These crystals were grown by edge defined film fed crystal growth （EFG） tech- nique. Thermoluminescence （TL） measurements were made on as grown （AG） and annealed （AN） crystals after they were irradiated with a gamma dose of 15 Gy. The influence and advantage of optimized Dy^3＋ concentration in enhancing the thermoluminescence （TL） properties of LiF：Mg samples were discussed. The normalized peak height of the annealed crystals was nearly 3 times that of the as grown crystals for the particular concentration samples irradiated with Co6~ gamma source showed linearity up to 10 Gy. Thermoluminescence signal observed over a period of one month showed negligible fading. Thermoluminescence glow curve structure of optimized phosphor remained stable for higher doses of gamma rays of 103 Gy. Glow curve was analyzed using computer glow curve deconvolution （CGCD） method and trapping parame- ters were calculated.
