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基于改进Zero−DCE模型的矿井低照度图像增强方法
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作者 王轶玮 李晓宇 +1 位作者 翁智 白凤山 《工矿自动化》 北大核心 2025年第2期57-64,99,共9页
煤矿井下监控图像中存在噪声,清晰度低,且颜色和纹理信息缺失,采用基于机器学习的图像增强方法时还面临低照度−正常照度图像配对数据集采集困难的问题。提出一种改进零参考深度曲线估计(Zero−DCE)模型,并将其应用于矿井低照度图像增强... 煤矿井下监控图像中存在噪声,清晰度低,且颜色和纹理信息缺失,采用基于机器学习的图像增强方法时还面临低照度−正常照度图像配对数据集采集困难的问题。提出一种改进零参考深度曲线估计(Zero−DCE)模型,并将其应用于矿井低照度图像增强。使用Leaky ReLU激活函数替换Zero−DCE模型中的ReLU激活函数,以加快模型收敛速度,提升低照度图像特征学习效率;在Zero−DCE模型浅层与深层网络之间的跳跃连接处引入卷积块注意力模块(CBAM),以提高模型对图像关键特征的表达能力;在浅层网络中引入非对称卷积块(ACB),以优化模型对局部图像特征的学习能力和细节特征的表现能力;在深层网络中采用串联卷积核(CCK),以降低模型参数量和计算量,缩短模型训练时间。采用LOL公共数据集和矿井自建数据集进行实验验证,结果表明:改进Zero−DCE模型的均方误差(MSE)、峰值信噪比(PSNR)、结构相似性(SSIM)、自然图像质量评估器(NIQE)和视觉信息保真度(VIF)整体上优于典型图像增强模型,在自建数据集上的MSE和NIQE较Zero−DCE模型分别降低16.25%和2.93%,PSNR,SSIM和VIF分别提高2.87%,1.87%和17.64%;图像增强视觉效果较好,可在提高图像亮度的同时有效保留细节纹理信息,降噪效果明显;对单幅图像的推理时间为0.138 s,可实现图像实时增强。 展开更多
关键词 矿井低照度图像 图像增强 零参考深度曲线估计网络 zero−DCE模型 无监督学习
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3种不同类型Twin-block矫治器对前牙应力分布和位移的影响
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作者 李星雨 张春艳 +8 位作者 李希贝 黄文莉 于少洋 杨文科 张映玥 郭骏 阎潇 张强 袁晓 《医用生物力学》 北大核心 2025年第4期844-850,共7页
目的 研究3种不同类型Twin-block矫治器对前牙、牙周膜及牙槽骨应力及位移的影响。方法 构建上下颌骨、关节盘、牙列及牙周膜的三维有限元模型。3组不同类型Twin-block矫治器的有限元模型分别为传统Twin-block矫治器、带切牙帽Twin-bloc... 目的 研究3种不同类型Twin-block矫治器对前牙、牙周膜及牙槽骨应力及位移的影响。方法 构建上下颌骨、关节盘、牙列及牙周膜的三维有限元模型。3组不同类型Twin-block矫治器的有限元模型分别为传统Twin-block矫治器、带切牙帽Twin-block矫治器、改良隐形Twin-block矫治器(clear twin-block aligner, CTBA)。所有类型矫治器的斜面角度均为70°,双侧分别加载200 N垂直于斜面的力。利用有限元方法分析前牙的应力分布与位移差异。结果 3种不同类型Twin-block矫治器均会导致上前牙舌倾及下前牙唇倾。CTBA组上前牙舌向位移及应力最大,最大应力为30.6 MPa,而下前牙唇向位移及应力最小,位移约为0.02 mm。同时CTBA组下前牙、牙周膜及牙槽骨所受等效应力在3组中最低,而传统Twin-block矫治器组最高。结论 在使用传统Twin-block矫治器治疗安氏Ⅱ类错[牙合]时,无论有无切牙帽,均会导致下前牙的唇倾;而与传统Twin-block矫治器相比,CTBA可减少对下前牙、牙槽骨、牙周膜应力和位移的影响,进而减小下前牙的牙周风险,但需注意上前牙舌向位移带来的舌倾效应。 展开更多
关键词 TWIN-block矫治器 功能矫治 隐形矫治器 安氏Ⅱ类错[牙合] 前牙
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Accidental zero modes in a multiorbital superconductor with spin-orbital coupling
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作者 XIANG Ke WANG Da WANG Qianghua 《物理学进展》 北大核心 2025年第5期250-259,共10页
The Majorana zero modes in vortex cores are of extensive interest in the context of topological quantum computing.However,a zero-energy bound state may arise accidentally but is not necessarily a Majorana zero mode.Su... The Majorana zero modes in vortex cores are of extensive interest in the context of topological quantum computing.However,a zero-energy bound state may arise accidentally but is not necessarily a Majorana zero mode.Such accidental zero modes should be carefully ruled out in experiment in order to identify the genuine Majorana zero modes.We show that in a spin-orbital coupled multi-band superconductor,such as the iron-selenide superconductor,accidental zero modes indeed arise in the vortex core if the pairing symmetry is the so-called nodeless d-wave(defined in the absence of spin-orbital coupling).Instead,if the pairing sym-metry is s_(++)or s_(+−)with respect to the Fermi pockets split by the spin-orbital coupling,the accidental zero modes do not appear in the limit of weak spin-orbital coupling.Our results are not only important in the experimental identification of Majorana zero modes,but also provide an avenue to pinpoint the pairing symmetry of the iron-selenide superconductor. 展开更多
关键词 spin-orbital coupling Andreev approximation accidental zero mode
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Block sparse compressed sensing with frames:Null space property and l_(2)/l_(q)(0
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作者 WU Fengong ZHONG Penghong QIN Yuehai 《中山大学学报(自然科学版)(中英文)》 北大核心 2025年第3期173-182,共10页
This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based ... This paper explores the recovery of block sparse signals in frame-based settings using the l_(2)/l_(q)-synthesis technique(0<q≤1).We propose a new null space property,referred to as block D-NSP_(q),which is based on the dictionary D.We establish that matrices adhering to the block D-NSP_(q)condition are both necessary and sufficient for the exact recovery of block sparse signals via l_(2)/l_(q)-synthesis.Additionally,this condition is essential for the stable recovery of signals that are block-compressible with respect to D.This D-NSP_(q)property is identified as the first complete condition for successful signal recovery using l_(2)/l_(q)-synthesis.Furthermore,we assess the theoretical efficacy of the l2/lq-synthesis method under conditions of measurement noise. 展开更多
关键词 Compressed sensing block sparse l2/lq-synthesis method null space property
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Differential-Linear Attacks on Ballet Block Cipher
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作者 ZHOU Yu CHEN Si-Wei +2 位作者 XU Sheng-Yuan XIANG Ze-Jun ZENG Xiang-Yong 《密码学报(中英文)》 北大核心 2025年第2期469-488,共20页
Ballet is one of the finalists of the block cipher project in the 2019 National Cryptographic Algorithm Design Competition.This study aims to conduct a comprehensive security evaluation of Ballet from the perspective ... Ballet is one of the finalists of the block cipher project in the 2019 National Cryptographic Algorithm Design Competition.This study aims to conduct a comprehensive security evaluation of Ballet from the perspective of differential-linear(DL)cryptanalysis.Specifically,we present an automated search for the DL distinguishers of Ballet based on MILP/MIQCP.For the versions with block sizes of 128 and 256 bits,we obtain 16 and 22 rounds distinguishers with estimated correlations of 2^(-59.89)and 2^(-116.80),both of which are the publicly longest distinguishers.In addition,this study incorporates the complexity information of key-recovery attacks into the automated model,to search for the optimal key-recovery attack structures based on DL distinguishers.As a result,we mount the key-recovery attacks on 16-round Ballet-128/128,17-round Ballet-128/256,and 21-round Ballet-256/256.The data/time complexities for these attacks are 2^(108.36)/2^(120.36),2^(115.90)/2^(192),and 2^(227.62)/2^(240.67),respectively. 展开更多
关键词 Ballet block cipher differential-linear(DL)cryptanalysis MILP/MIQCP distinguisher key-recovery attacks
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P-block基金属原子在TiO_(2)(110)表面的吸附及扩散性质研究
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作者 丁雅妮 郭梦雨 +3 位作者 王博涵 贾晨怡 王美娟 史金磊 《原子与分子物理学报》 CAS 北大核心 2025年第6期17-21,共5页
基于密度泛函理论的第一性原理计算方法,我们系统研究了p-block金属原子(Sn,Sb,Bi和Te)在TiO_(2)(110)表面上的吸附及扩散行为.计算结果表明Sn,Sb及Bi金属原子在TiO_(2)(110)表面上具有较大的吸附能和较高的扩散势垒,倾向于形成分散的p-... 基于密度泛函理论的第一性原理计算方法,我们系统研究了p-block金属原子(Sn,Sb,Bi和Te)在TiO_(2)(110)表面上的吸附及扩散行为.计算结果表明Sn,Sb及Bi金属原子在TiO_(2)(110)表面上具有较大的吸附能和较高的扩散势垒,倾向于形成分散的p-block单原子,然而对于Te金属原子,由于其与衬底结合能相对较弱且扩散势垒较低而更倾向于形成团簇,该研究结果有助于为实验上构建基于p-block的金属单原子催化剂提供理论依据. 展开更多
关键词 p-block单原子催化剂 吸附及扩散势垒 第一性原理计算
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基于M2-MHA Block轻量化模型的小样本跨工况轴承故障诊断
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作者 邓兴超 朱冠华 +2 位作者 张清华 张发振 赵乾惠 《机床与液压》 北大核心 2025年第7期31-39,共9页
针对轴承故障诊断中存在的训练数据不充分、模型泛化能力差以及计算复杂度大等问题,提出一种基于轻量化卷积神经网络的小样本跨工况轴承故障诊断方法。采用原始振动信号与量纲一量辅助数据集的并行输入方式,搭建基于深度可分离卷积的多... 针对轴承故障诊断中存在的训练数据不充分、模型泛化能力差以及计算复杂度大等问题,提出一种基于轻量化卷积神经网络的小样本跨工况轴承故障诊断方法。采用原始振动信号与量纲一量辅助数据集的并行输入方式,搭建基于深度可分离卷积的多输入多尺度(M2)特征提取架构,避免了仅使用原始振动信号可能导致的特征不充分问题。此外,提出一种多头注意力块(MHA Block),以提升训练效率和诊断性能。最后,通过迁移学习技术实现了基于小样本的跨工况诊断,并在凯斯西储大学数据集上进行实验验证。结果表明:所提方法在源域下的平均诊断精度达99.8%,且模型参数量和模型大小仅分别为28 789和540.5 kB;在小样本跨工况迁移诊断中,采用100个样本进行训练、500个样本进行测试,平均诊断精度高达99.3%;文中所提方法能够在低计算量条件下,实现高准确率与良好的泛化性能。 展开更多
关键词 故障诊断 轻量化 多输入多尺度 多头注意力块 小样本 跨工况
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Correlation between movement of tectonicblocks and earthquakes in groups 被引量:12
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作者 范俊喜 马瑾 +1 位作者 刁桂苓 单新建 《地震学报》 CSCD 北大核心 2001年第5期514-522,共9页
The Chinese mainland is divided into some tectonic blocks by nearly NE- and EW-orientated faults. Meanwhile strong earthquakes in the Chinese mainland usually cluster in time and space. We call earthquakes in groups. ... The Chinese mainland is divided into some tectonic blocks by nearly NE- and EW-orientated faults. Meanwhile strong earthquakes in the Chinese mainland usually cluster in time and space. We call earthquakes in groups. Tectonic blocks separated by faults and earthquakes in groups are prominent features of the tectonics of the Chi-nese mainland. Correlation between movement of tectonic blocks and groups of earthquakes is discussed in this paper. The results show that earthquakes in groups often occurred at one or several block boundary faults. The released elastic strain energy is built up in the same periods and around blocks. It means that strong earthquakes in groups are mainly caused by movement of blocks. Four types of block movement are identified based ongroup earthquakes: movement along a single boundary of a block (or a combined blocks), movement of a single block, movement of multi-blocks, and movement in block interiors. If we consider distribution of all strong earthquakes occurred in the Chinese mainland, the movement along a single boundary of a block is more popular one inducing strong earthquakes. But if we only consider earthquakes in groups rather than single earthquakesthe movement of a block dominates among four modes. Statistics with respect to group earthquakes show that the Taihangshan mountain and the North China block are much active in the eastern part of Chinese mainland, and in western part of Chinese mainland the active blocks are Sichuan-Yunnan and the Kunlun-Songpan ones. 展开更多
关键词 成组地震 地块活动方式 中国大陆 地震构造 地震活动 断层
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舌系带成形术联合Twin-block矫治器治疗生长发育期下颌后缩患者的效果
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作者 陈宏吉 宋娟 邓末宏 《实用医学杂志》 北大核心 2025年第9期1352-1360,共9页
目的 探讨舌系带成形术联合Twin-block矫治器对生长发育期下颌后缩患者的临床疗效。方法 2023年8月至2024年8月就诊的42例骨性Ⅱ类错[牙合]并伴有下颌后缩及舌系带过短患者,按随机数字表法分为对照组和观察组各21例。对照组给予Twin-bl... 目的 探讨舌系带成形术联合Twin-block矫治器对生长发育期下颌后缩患者的临床疗效。方法 2023年8月至2024年8月就诊的42例骨性Ⅱ类错[牙合]并伴有下颌后缩及舌系带过短患者,按随机数字表法分为对照组和观察组各21例。对照组给予Twin-block矫治器治疗,观察组给予舌系带成形术联合Twin-block矫治器治疗。比较两组矫治时间及治疗前后进行简化Hazelbaker舌系带功能评估工具(HATLFF)评分以及舌系带长度测量。两组患者治疗前后均进行口腔锥形束计算机断层扫描(CBCT),采用三维重建和头影测量分析舌与舌骨、上气道、上下颌骨和颞下颌关节的相关指标。结果 对照组矫治时间[(10.14±1.06)个月]显著长于观察组矫治时间[(8.00±1.41)个月],差异有统计学意义(P <0.05)。治疗前,对照组和观察组简化HATLFF评分、舌系带长度以及舌与舌骨、上气道、上下颌骨和颞下颌关节的相关指标比较差异无统计学意义(P> 0.05)。治疗后,观察组简化HATLFF评分和舌系带长度显著高于治疗前(P <0.05),对照组和观察组IP-CP、IP-RP、ANB、U1-SN、U1-NA角、U1-NA距、FCA和关节结节倾斜角均显著低于治疗前(P <0.05),T-S、H-NP、H-CVP、H-Or、H-PP、H-MP、H-FH、H-PNS、上气道总体积、腭咽体积、舌咽体积、CL-CR、ML-MR、SNB、GoGn-SN、Go-Gn、Co-Gn、Co-Go、Ar-Go、L1-NB角、L1-NB距、L1-MP角、L1-MP距、SL、SE、Z、UI-PP、L6-MP、关节窝宽度、髁突顶部矢状面面积、髁状突高度、髁突顶部冠状面面积均显著高于治疗前(P <0.05)。治疗后,观察组ANB差值显著低于对照组差值(P <0.05),简化HATLFF评分、舌系带长度、T-S、H-Or、H-PP、H-FH、上气道总体积、腭咽体积、舌咽体积、CL-CR、ML-MR、Go-Gn、Ar-Go、L1-NB角、L1-NB距、SL、SE和L6-MP差值显著高于对照组差值(P <0.05)。结论 舌系带成形术联合Twin-block矫治器对生长发育期下颌后缩患者的矫治时间以及治疗效果优于单一Twin-block矫治器。 展开更多
关键词 下颌后缩 骨性Ⅱ类错[牙合] 舌系带过短 TWIN-block矫治器 舌系带成形术 生长发育期 口腔锥形束计算机断层扫描 颞下颌关节
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分组密码算法uBlock积分攻击的改进
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作者 王晨 崔佳敏 +1 位作者 李木舟 王美琴 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第5期2149-2158,共10页
积分攻击是由Daemen等人(doi:10.1007/BFb0052343)于1997年提出的一种密码分析方法,是继差分分析和线性分析之后最有效的密码分析方法之一。作为2018年全国密码算法设计竞赛分组算法的获胜算法,uB-lock抵抗积分攻击的能力受到较多的关... 积分攻击是由Daemen等人(doi:10.1007/BFb0052343)于1997年提出的一种密码分析方法,是继差分分析和线性分析之后最有效的密码分析方法之一。作为2018年全国密码算法设计竞赛分组算法的获胜算法,uB-lock抵抗积分攻击的能力受到较多的关注。为了重新评估uBlock家族密码算法抵抗积分攻击的安全性,该文利用单项式传播技术,结合混合整数线性规划(MILP)工具搜索积分区分器,并利用部分和技术进行密钥恢复攻击。对于uBlock-128/128和uBlock-128/256,基于搜索到的9轮积分区分器分别进行了首个11轮和12轮攻击,数据复杂度为2~(127)选择明文,时间复杂度分别为2~(127.06)和2~(224)次加密,存储复杂度分别为2~(44.58)和2~(138)字节;对于uBlock-256/256,基于搜索到的10轮积分区分器进行了首个12轮攻击,数据复杂度为2~(253)选择明文,时间复杂度为2~(253.06)次加密,存储复杂度为2~(44.46)字节。与之前uBlock的最优积分攻击结果相比,uBlock-128/128和uBlock-256/256的攻击轮数分别提高2轮,uBlock-128/256的攻击轮数提高3轮。本文的攻击说明,uBlock针对积分攻击依然有足够的安全冗余。 展开更多
关键词 密码分析 分组密码 ublock 积分攻击
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Study on the Theory and Method on Identification of the Mobile Block in the Face-Contacted Blocks Structure in Rocks Between Coal Seams to Mine the Left-over Coal Above the Gob
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作者 Guorui Feng,Lixun Kang,Xuyan Zhang Institute of Mining Technology,Taiyuan University of Technology,Taiyuan 030024,China. 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期180-180,共1页
In mining the left-over coal above the gob,stope wall rock of mining area have hard limestone.through field observation,the face-contacted block structure was found in rocks between coal seams to mine the left-over co... In mining the left-over coal above the gob,stope wall rock of mining area have hard limestone.through field observation,the face-contacted block structure was found in rocks between coal seams to mine the left-over coal above the gob.In order to probe into the movement law of rock strata and strata control measures,it is very important to identify the mobile block in face-contacted block structure of rocks between coal seams.This paper relies on the thought of block theory to establish appropriate parameter matrix and figure out its discrimination matrix in view of the fact that the block in face-contacted block structure has high intensity and stiffness,the 展开更多
关键词 MOBILE block ROCKS BETWEEN COAL seams rock mechanics IDENTIFICATION of the MOBILE block
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Analysis of an improved trajectory correction scheme based on mass blocks
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作者 LEI Xiaoyun ZHANG Zhian DU Zhonghua 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2019年第1期180-190,共11页
In conventional technical trajectory correction schemes,continuous attitude adjusting mechanisms, such as canards, are inferior in terms of response time and efficiency of executing instructions. Discontinuous attitud... In conventional technical trajectory correction schemes,continuous attitude adjusting mechanisms, such as canards, are inferior in terms of response time and efficiency of executing instructions. Discontinuous attitude adjusting mechanisms, such as the lateral pulse jet, have complex impact on the airflow layer of the projectile surface caused by the thrust vector jet flow. An improved two-dimensional trajectory correction mechanism is designed based on the principle of firing mass blocks by a tailor-made propellant. The mechanical properties of the thrust force(namely the correction force) is analyzed. The trajectory correction model is established to analyze the effects of correction starting moment and correction phase angle of a thrust force on the projectile's trajectory. According to the trajectory correction scheme, an improved genetic algorithm is employed to this work. The scheme is tested in the simulation. The results show that the correction scheme is effective to reduce target dispersion and increase the precision of the impact point. 展开更多
关键词 TRAJECTORY CORRECTION MASS block CORRECTION force CORRECTION control ALGORITHM GENETIC algorithm.
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Appropriate schemata and building blocks
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作者 YangHaijun LiMinqiang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第2期451-455,F003,共6页
Appropriate schemata as a novel concept to characterize building blocks are introduced, and then, the traits of appropriate schemata are presented. The effects of building blocks by search operators are analyzed. Henc... Appropriate schemata as a novel concept to characterize building blocks are introduced, and then, the traits of appropriate schemata are presented. The effects of building blocks by search operators are analyzed. Hence, the experiments on RR-8X8 are employed to verify that appropriate schemata construct the building blocks. The validity of appropriate schemata and building blocks from the views of theory and practice is presented. 展开更多
关键词 genetic algorithms appropriate schemata building blocks.
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基于Group-Res2Block的智能合成语音说话人确认方法
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作者 李菲 苏兆品 +2 位作者 王年松 杨波 张国富 《应用科学学报》 CAS CSCD 北大核心 2024年第4期709-722,共14页
针对现有说话人确认任务基于自然语音条件下并不适用于智能合成语音的问题,提出一种基于Group-Res2Block的智能合成语音说话人确认方法。首先,设计了Group-Res2Block结构,在Res2Block的基础上将当前分组与相邻前后分组进行合并形成新的... 针对现有说话人确认任务基于自然语音条件下并不适用于智能合成语音的问题,提出一种基于Group-Res2Block的智能合成语音说话人确认方法。首先,设计了Group-Res2Block结构,在Res2Block的基础上将当前分组与相邻前后分组进行合并形成新的分组,以增强说话人局部特征的上下文联系;其次,设计了并行结构的多尺度通道注意力特征融合机制,利用不同大小卷积核实现同一层级的特征在通道维度的特征选择,以获取更具表现力的说话人特征,避免信息冗余;最后,设计了串行结构的多尺度层注意力特征融合机制,构建层结构,将深浅层特征整体进行融合并赋予不同权重,以获取最优的特征表达。为验证所提出特征提取网络的有效性,构建了中英文两种智能合成语音数据集进行消融实验和对比实验。结果表明本文方法在该任务的评价指标精确度(accuracy,ACC)、等错误率(equal error rate,EER)和最小检测代价函数(minimum detection cost function,minDCF)上是最优的。此外,通过对模型泛化性能进行测试,验证了本文方法对未知智能语音算法的适用性。 展开更多
关键词 说话人确认 智能合成语音 Group-Res2block深度神经网络 多尺度特征 注意力机制
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EGFR antisense RNA blocks expression of the epidermal growth factor receptor and partially reverse the malignant phenotype of human cancer cells
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作者 Wenhong Fan, Yinglin Lu, P. H. Tang, Xueming Ge, Shuang LiuDepartment of Molecular Pathology, Institute of Basic Medical Sciences, Beijing 100850 《中国实验血液学杂志》 CAS CSCD 1997年第3期294-294,共1页
Objective: Overexpression of the membraneepidermal growth factor receptor (EGFR) in humantumor cells predicts for poor prognosis. Hence, weexperimentally investigated the effects of humanEGFR to the malignant phenotyp... Objective: Overexpression of the membraneepidermal growth factor receptor (EGFR) in humantumor cells predicts for poor prognosis. Hence, weexperimentally investigated the effects of humanEGFR to the malignant phenotype in humen breastcancer cell line MDA-MB-231 and humannasopharyngeal carcinoma cell line CNE-2. Methods: 展开更多
关键词 phenotype ANTISENSE RNA prognosis PARTIALLY blocks NUDE inhibited targeted LIPOFECTAMINE
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Research on supply chain management of complex product system based on blockchain
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作者 DING Jie WANG Qingguo +1 位作者 ZHANG Haifeng ZANG Xuejing 《Journal of Systems Engineering and Electronics》 CSCD 2024年第6期1530-1541,共12页
Blockchain technology has attracted worldwide atten-tion,and has strong application potential in complex product system supply chain and other fields.This paper focuses on the supply chain management issues of complex... Blockchain technology has attracted worldwide atten-tion,and has strong application potential in complex product system supply chain and other fields.This paper focuses on the supply chain management issues of complex product systems,and combines the technical characteristics of blockchain,such as tamper resistance and strong resistance to destruction,to conduct research on the application of blockchain based supply chain management for complex product systems.The block-chain technology is integrated into functional modules such as business interaction,privacy protection,data storage,and sys-tem services.The application technology architecture of com-plex product system supply chain integrated with blockchain is constructed.The application practice in complex product sys-tem supply chain is carried out.The results show that the sup-ply chain of complex product systems has the functions of traceability,cost reduction,and anti-counterfeiting protection.Finally,the future development direction and research focus of the complex product system supply chain based on blockchain are prospected,which provides a reference for the equipment manufacturing supply chain management in the mili-tary industry. 展开更多
关键词 supply chain block chain complex product system
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后入路腰方肌阻滞在腹腔镜子宫肌瘤剔除术中的应用 被引量:3
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作者 王丽薇 敦元莉 +3 位作者 姚瑶 吴长毅 张坤 曲音音 《中国微创外科杂志》 北大核心 2025年第2期75-80,共6页
目的探讨后入路腰方肌阻滞(posterior quadratus lumborum block,PQLB)在腹腔镜子宫肌瘤剔除术中应用的安全性。方法回顾性分析我院妇科2021年7月~2024年7月62例腹腔镜子宫肌瘤剔除术的临床资料,根据术前阻滞方式分为2组:PQLB组和腹横... 目的探讨后入路腰方肌阻滞(posterior quadratus lumborum block,PQLB)在腹腔镜子宫肌瘤剔除术中应用的安全性。方法回顾性分析我院妇科2021年7月~2024年7月62例腹腔镜子宫肌瘤剔除术的临床资料,根据术前阻滞方式分为2组:PQLB组和腹横肌平面(transversus abdominis plane,TAP)阻滞组(TAP组),每组31例。PQLB组在超声引导下行双侧PQLB,每侧给予0.35%罗哌卡因20 ml。TAP组在超声引导下行双侧TAP阻滞,每侧给予0.4%或0.5%罗哌卡因20 ml。记录患者麻醉前(T_(0))、阻滞时(T_(1))、手术切皮时(T_(2))和苏醒期(T_(3))平均动脉压和心率,局麻药毒性反应,神经损伤,术中麻醉性镇痛药物用量,术后补救性镇痛药物的种类与用量,术后恶心呕吐(postoperative nausea and vomiting,PONV)等并发症的发生情况等。结果62例均顺利完成手术。PQLB组与TAP组4个时间点平均动脉压(F=0.323,P=0.572)、心率(F=0.195,P=0.660)差异均无显著性。2组术中阿片类镇痛药物用量(Z=-0.458,P=0.647)和住院时间(Z=-1.652,P=0.099)差异均无显著性。PQLB组术后补救性镇痛药物使用率显著低于TAP组(32.3%vs.74.2%,χ^(2)=10.949,P=0.000)。PQLB组术后48 h内非甾体类抗炎药用量显著低于TAP组[0(0,0)mg vs.400(0,1600)mg,Z=-4.849,P=0.000],阿片类(曲马多)用量无显著差异(Z=-0.045,P=0.964)。2组PONV发生率差异无显著性(P>0.05)。PQLB组患者术后12、24 h腹壁痛和内脏痛数字疼痛评定量表评分均未超过3分。所有患者均未发生局麻药毒性反应和神经损伤。结论PQLB可以为腹腔镜子宫肌瘤剔除术患者提供完善的镇痛,对于内脏痛有更好的抑制作用,有助于减少术后麻醉性镇痛药用量。 展开更多
关键词 腰方肌阻滞 腹横筋膜阻滞 腹腔镜子宫肌瘤剔除术
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计及电网参数不平衡的灵活接地系统高阻接地故障选线方法 被引量:2
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作者 李晓波 张世乐 +3 位作者 谢剑锋 彭超红 刘栩鹏 梁睿 《电力系统保护与控制》 北大核心 2025年第5期59-68,共10页
灵活接地系统采用的零序过电流保护存在耐过渡电阻能力低的问题,并且现有的选线方法对互感器精度要求较高,也未考虑电网参数不平衡对判据的影响,存在保护误判的风险。针对上述问题,首先在计及电网参数不平衡条件下,探究了并联小电阻投... 灵活接地系统采用的零序过电流保护存在耐过渡电阻能力低的问题,并且现有的选线方法对互感器精度要求较高,也未考虑电网参数不平衡对判据的影响,存在保护误判的风险。针对上述问题,首先在计及电网参数不平衡条件下,探究了并联小电阻投入前后各电气信号变化量与线路对地参数、不平衡电流的关系。研究发现健全线路零序电流变化量与零序电压变化量之比等于该线路对地导纳,故障线路的零序电流变化量与零序电压变化量之比则为线路对地导纳与接地导纳的总和。在此基础上,提出了一种适用于灵活接地系统单相高阻接地故障的选线方法。该方法不受电网参数不平衡与零序CT极性反接影响,能够有效降低保护对互感器精度的要求。此外,该方法还可利用故障信息实现电网参数不平衡条件下对过渡电阻及单条线路对地导纳的测量。最后,在搭建的仿真电路中验证了所述方法的正确性和有效性。 展开更多
关键词 灵活接地系统 电网参数不平衡 零序电压变化量 零序电流变化量 高阻接地故障
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TEMPORAL SPATIAL VARIATION CHARACTERISTICS OF CRUST DEFORMATION OF ACTIVE TECTONIC BLOCKS IN NORTH CHINA
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作者 Xu Caijun, Li Zhicai and Wang Hua (School of Geodesy and Geomatics, Wuhan University, Wuhan 430079,China) 《大地测量与地球动力学》 CSCD 2003年第B12期41-49,共9页
Global Positioning System (GPS) observations during four measurement campaigns from 1992 to 1999 are used in a study of the temporal and spatial variation characteristics of crustal deformation of active tectonic bloc... Global Positioning System (GPS) observations during four measurement campaigns from 1992 to 1999 are used in a study of the temporal and spatial variation characteristics of crustal deformation of active tectonic blocks in North China. The Euler vectors for these active blocks are determined on the basis of GPS velocities of a group relative stable points in 1992,1995,1996 and in 1996,1999 respectively. We have studied the relative motion between blocks at the boundaries and the intra block deformation field. We have also inverted the strain rate fields for these active blocks by bi cubic spline model based on the GPS velocity field. The results show that the intra block deformation rates are different from those in block boundary zones, and are also different in different periods; the deformational field is generally characterized by intra-block extension in North China. 展开更多
关键词 活动板块 表层变形 中国北方 瞬时空间变化特性 边缘区的运动 应力等级场 地质结构 内部变形
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基于图像-文本大模型CLIP微调的零样本参考图像分割 被引量:2
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作者 刘杰 乔文昇 +2 位作者 朱佩佩 雷印杰 王紫轩 《计算机应用研究》 北大核心 2025年第4期1248-1254,共7页
近年来,以CLIP为代表的视觉-语言大模型在众多下游场景中显示出了出色的零样本推理能力,然而将CLIP模型迁移至需要像素水平图-文理解的参考图像分割中非常困难,其根本原因在于CLIP关注图像-文本整体上的对齐情况,却丢弃了图像中像素点... 近年来,以CLIP为代表的视觉-语言大模型在众多下游场景中显示出了出色的零样本推理能力,然而将CLIP模型迁移至需要像素水平图-文理解的参考图像分割中非常困难,其根本原因在于CLIP关注图像-文本整体上的对齐情况,却丢弃了图像中像素点的空间位置信息。鉴于此,以CLIP为基础模型,提出了一种单阶段、细粒度、多层次的零样本参考图像分割模型PixelCLIP。具体地,采取了多尺度的图像特征融合,既聚集CLIP中不同视觉编码器提取的图像像素级特征,同时又考虑CLIP中固有的图像整体语义特征。在文本信息表征上,不但依靠CLIP-BERT来保持物体种类信息,还引入LLaVA大语言模型进一步注入上下文背景知识。最后,PixelCLIP通过细粒度跨模态关联匹配,实现像素水平的参考图像分割。充分的数值分析结果验证了该方法的有效性。 展开更多
关键词 零样本 CLIP 像素级 单阶段 参考图像分割
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