大多数基于深度学习技术的视觉设备都配备了图像信号处理(Image Signal Processing, ISP)过程以实现RAW数据到RGB图像的转换,同时集成数据预处理过程以完成高效的图像处理。该文在同时考虑ISP和数据预处理过程影响基础上,搭建了深度学...大多数基于深度学习技术的视觉设备都配备了图像信号处理(Image Signal Processing, ISP)过程以实现RAW数据到RGB图像的转换,同时集成数据预处理过程以完成高效的图像处理。该文在同时考虑ISP和数据预处理过程影响基础上,搭建了深度学习视觉应用实验平台,提出针对ISP过程的图像缩放攻击,即精心制作对抗RAW经过ISP过程得到攻击图像,一旦缩放到特定尺寸就会呈现出完全不同的样貌。由于所提出的攻击是由基于ISP过程的梯度驱动的,因此构建了一个等效模型来学习目标ISP的转换过程,利用等效模型的近似梯度来发动攻击。该攻击平台的构建涵盖了深度学习算法、图像处理及对抗攻击优化等内容,有助于学生深入学习和理解基于深度学习视觉应用的任务处理原理以及深度学习模型的弱点,培养学生针对复杂算法问题的创新与实践能力。展开更多
The Jiapigou gold deposits are typical vein type deposits associated withArchaean greenstone belts in China. According to the crosscutting relationships between dykesand auriferous veins, single hydrothermal zircon U-...The Jiapigou gold deposits are typical vein type deposits associated withArchaean greenstone belts in China. According to the crosscutting relationships between dykesand auriferous veins, single hydrothermal zircon U-Pb dating and quartz K-Ar,<sup>40</sup>Ar-<sup>39</sup>Ar andRb-Sr datings, the main mineralization stage of the Jiapigou deposit has been determined to be2469-2475 Ma, while mineralization superimposition on the gold deposit occurred in1800-2000 Ma and 130-272 Ma. They form a mineralization framework of one oldermetallogenic epoch （Late Archaean-Early Proterozoic） and one younger metallogenic epoch（Mesozoic） of gold deposits in Archaean greenstone belts in China.展开更多
The existing researches on surfactant micellar solutions mainly focus on the formulation optimization and core flooding test, and the types and mechanisms of cleanup additives suitable for low permeability reservoir r...The existing researches on surfactant micellar solutions mainly focus on the formulation optimization and core flooding test, and the types and mechanisms of cleanup additives suitable for low permeability reservoir remain unclear. The flowback efficiencies of different types of surfactant micellar solutions were evaluated by core experiments, a multi-level pore-throat system micromodel characterizing pore-throat structures of low permeability reservoir was made, and flooding and flowback experiments of brine and surfactant micellar solutions of different salinities were conducted with the micromodel to show the oil flowback process in micron pores under the effect of surfactant micellar solution visually and reveal the mechanisms of enhancing displacement and flowback efficiency of surfactant micellar solution. During the displacement and flowback of brine and low salinity surfactant micellar solution, many small droplets were produced, when the small droplets passed through pore-throats, huge percolation resistance was created due to Jamin’s effect, leading to the rise of displacement and flowback pressure differences and the drop of flowback efficiency. The surfactant micellar solutions with critical salinity and optimal salinity that were miscible with crude oil to form Winsor Ⅲ micro-emulsion didnot produce mass small droplets, so they could effectively reduce percolation resistance and enhance oil displacement and flowback efficiency.展开更多
Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shiji...Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shijiutuo Bulge,Chengning Uplift,Bohai Bay Basin were investigated.A new approach to calculate the occurrence of the sand-mudstone interfaces using resistivity log of horizontal well was advanced to solve the multiple solution problem of abandoned channel’s orientation.This method uses the trigonometric function relationship between radius,dip and length of the resistivity log to calculate the occurrence qualitatively-quantitatively to help determine the true direction of the abandoned channels.This method can supplement and improve the architecture dissection technique for meandering river sandbodies.This method was used to study the dip angle and scale of the lateral accretion layers in point bar quantitatively to help determine the spatial distribution of lateral accretion layers.The fine architecture model of underground meandering river reservoir in the study area has been established.Different from traditional grids,different grid densities for lateral accretion layers and bodies were used in this model by non-uniform upscaling to establish the inner architecture model of point-bars and realize industrial numerical simulation of the whole study area.The research results can help us predict the distribution of remaining oil,tap remaining oil,and optimize the waterflooding in oilfields.展开更多
目的探讨超声造影(CEUS)对慢性肝病背景下最大径≤3 cm肝细胞肝癌(HCC)的诊断价值。方法选取我院收治的189例慢性肝病患者(共252个肝脏局灶性病变),均行CEUS检查,观察HCC增强模式,比较最大径>2 cm与≤2 cm HCC增强模式的差异。以组...目的探讨超声造影(CEUS)对慢性肝病背景下最大径≤3 cm肝细胞肝癌(HCC)的诊断价值。方法选取我院收治的189例慢性肝病患者(共252个肝脏局灶性病变),均行CEUS检查,观察HCC增强模式,比较最大径>2 cm与≤2 cm HCC增强模式的差异。以组织病理学或临床诊断结果为金标准,计算HCC典型增强模式及其联合不典型增强模式对最大径≤3 cm HCC的诊断准确率、灵敏度、特异度;绘制受试者工作特征曲线评估其诊断效能。结果252个病灶中,HCC 95个(最大径>2 cm 39个,最大径≤2 cm 56个),其他恶性肿瘤24个,良性病灶133个。HCC动脉期、门脉期、延迟期主要表现为高-等-低增强(38.95%,37/95)和高-低-低增强(29.47%,28/95)的典型增强模式,28.42%(27/95)呈不典型增强模式。最大径>2 cm HCC典型增强模式占比高于最大径≤2 cm HCC(82.05%vs.58.93%),不典型增强模式占比低于最大径≤2 cm HCC(12.82%vs.39.27%),差异均有统计学意义(均P<0.05)。典型增强模式对最大径≤3 cm HCC的诊断准确率、灵敏度、特异度分别为84.52%、65.26%、96.18%,曲线下面积为0.807;其联合不典型增强模式的诊断准确率、灵敏度、特异度分别为93.65%、93.68%、93.63%,曲线下面积为0.937;除特异度外,其余诊断效能与典型增强模式比较差异均有统计学意义(均P<0.05)。结论HCC病灶越小CEUS呈不典型增强模式占比越高;联合典型与不典型增强模式有助于提高对慢性肝病背景下最大径≤3 cm HCC的诊断效能,具有较好的临床价值。展开更多
文摘大多数基于深度学习技术的视觉设备都配备了图像信号处理(Image Signal Processing, ISP)过程以实现RAW数据到RGB图像的转换,同时集成数据预处理过程以完成高效的图像处理。该文在同时考虑ISP和数据预处理过程影响基础上,搭建了深度学习视觉应用实验平台,提出针对ISP过程的图像缩放攻击,即精心制作对抗RAW经过ISP过程得到攻击图像,一旦缩放到特定尺寸就会呈现出完全不同的样貌。由于所提出的攻击是由基于ISP过程的梯度驱动的,因此构建了一个等效模型来学习目标ISP的转换过程,利用等效模型的近似梯度来发动攻击。该攻击平台的构建涵盖了深度学习算法、图像处理及对抗攻击优化等内容,有助于学生深入学习和理解基于深度学习视觉应用的任务处理原理以及深度学习模型的弱点,培养学生针对复杂算法问题的创新与实践能力。
基金This study is a contribution to Project 90051-01,a state key gold scientific and technological project during the 8th Five-Year Plan period,and Project 92-94-40 carried out by the State Gold Administration.
文摘The Jiapigou gold deposits are typical vein type deposits associated withArchaean greenstone belts in China. According to the crosscutting relationships between dykesand auriferous veins, single hydrothermal zircon U-Pb dating and quartz K-Ar,<sup>40</sup>Ar-<sup>39</sup>Ar andRb-Sr datings, the main mineralization stage of the Jiapigou deposit has been determined to be2469-2475 Ma, while mineralization superimposition on the gold deposit occurred in1800-2000 Ma and 130-272 Ma. They form a mineralization framework of one oldermetallogenic epoch （Late Archaean-Early Proterozoic） and one younger metallogenic epoch（Mesozoic） of gold deposits in Archaean greenstone belts in China.
基金Supported by the China National Science and Technology Major Project (2017ZX05009-005-003)Research Fund of China University of Petroleum (Beijing)(2462019QNXZ04)。
文摘The existing researches on surfactant micellar solutions mainly focus on the formulation optimization and core flooding test, and the types and mechanisms of cleanup additives suitable for low permeability reservoir remain unclear. The flowback efficiencies of different types of surfactant micellar solutions were evaluated by core experiments, a multi-level pore-throat system micromodel characterizing pore-throat structures of low permeability reservoir was made, and flooding and flowback experiments of brine and surfactant micellar solutions of different salinities were conducted with the micromodel to show the oil flowback process in micron pores under the effect of surfactant micellar solution visually and reveal the mechanisms of enhancing displacement and flowback efficiency of surfactant micellar solution. During the displacement and flowback of brine and low salinity surfactant micellar solution, many small droplets were produced, when the small droplets passed through pore-throats, huge percolation resistance was created due to Jamin’s effect, leading to the rise of displacement and flowback pressure differences and the drop of flowback efficiency. The surfactant micellar solutions with critical salinity and optimal salinity that were miscible with crude oil to form Winsor Ⅲ micro-emulsion didnot produce mass small droplets, so they could effectively reduce percolation resistance and enhance oil displacement and flowback efficiency.
基金Supported by the China National Science and Technology Major Project(2008ZX05030-005-012011ZX05004-004-007).
文摘Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shijiutuo Bulge,Chengning Uplift,Bohai Bay Basin were investigated.A new approach to calculate the occurrence of the sand-mudstone interfaces using resistivity log of horizontal well was advanced to solve the multiple solution problem of abandoned channel’s orientation.This method uses the trigonometric function relationship between radius,dip and length of the resistivity log to calculate the occurrence qualitatively-quantitatively to help determine the true direction of the abandoned channels.This method can supplement and improve the architecture dissection technique for meandering river sandbodies.This method was used to study the dip angle and scale of the lateral accretion layers in point bar quantitatively to help determine the spatial distribution of lateral accretion layers.The fine architecture model of underground meandering river reservoir in the study area has been established.Different from traditional grids,different grid densities for lateral accretion layers and bodies were used in this model by non-uniform upscaling to establish the inner architecture model of point-bars and realize industrial numerical simulation of the whole study area.The research results can help us predict the distribution of remaining oil,tap remaining oil,and optimize the waterflooding in oilfields.
文摘目的探讨超声造影(CEUS)对慢性肝病背景下最大径≤3 cm肝细胞肝癌(HCC)的诊断价值。方法选取我院收治的189例慢性肝病患者(共252个肝脏局灶性病变),均行CEUS检查,观察HCC增强模式,比较最大径>2 cm与≤2 cm HCC增强模式的差异。以组织病理学或临床诊断结果为金标准,计算HCC典型增强模式及其联合不典型增强模式对最大径≤3 cm HCC的诊断准确率、灵敏度、特异度;绘制受试者工作特征曲线评估其诊断效能。结果252个病灶中,HCC 95个(最大径>2 cm 39个,最大径≤2 cm 56个),其他恶性肿瘤24个,良性病灶133个。HCC动脉期、门脉期、延迟期主要表现为高-等-低增强(38.95%,37/95)和高-低-低增强(29.47%,28/95)的典型增强模式,28.42%(27/95)呈不典型增强模式。最大径>2 cm HCC典型增强模式占比高于最大径≤2 cm HCC(82.05%vs.58.93%),不典型增强模式占比低于最大径≤2 cm HCC(12.82%vs.39.27%),差异均有统计学意义(均P<0.05)。典型增强模式对最大径≤3 cm HCC的诊断准确率、灵敏度、特异度分别为84.52%、65.26%、96.18%,曲线下面积为0.807;其联合不典型增强模式的诊断准确率、灵敏度、特异度分别为93.65%、93.68%、93.63%,曲线下面积为0.937;除特异度外,其余诊断效能与典型增强模式比较差异均有统计学意义(均P<0.05)。结论HCC病灶越小CEUS呈不典型增强模式占比越高;联合典型与不典型增强模式有助于提高对慢性肝病背景下最大径≤3 cm HCC的诊断效能,具有较好的临床价值。
