期刊文献+
共找到7,132篇文章
< 1 2 250 >
每页显示 20 50 100
A new insight into LPSO phase transformation and mechanical properties uniformity of large-scale Mg-Gd-Y-Zn-Zr alloy prepared by multi-pass friction stir processing 被引量:1
1
作者 Xiaohu Guan Wen Wang +7 位作者 Ting Zhang Pai Peng Qiang Liu Peng Han Ke Qiao Jun Cai Liqiang Wang Kuaishe Wang 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第5期2041-2056,共16页
A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long peri... A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate. 展开更多
关键词 Friction stir processing MULTI-PASS Mg-Gd-Y-Zn-Zr alloy LPSO phase transformation Mechanical properties
下载PDF
Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process
2
作者 Yu-Guo Li Chen He +2 位作者 Chun-Mao Chen Fan Liu Quan Shi 《Petroleum Science》 SCIE EI CAS CSCD 2024年第3期2112-2119,共8页
Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD... Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD)and organic sulfur contents.Even after the recovery of H_(2)S from the sour water by the stripping process,the effluent still contains a high concentration of dissolved organic sulfur(DOS),which can have a huge bad influence.While chemical composition of dissolved organic matter(DOM)in refinery wastewater has been extensively studied,the investigation of recalcitrant DOS from sour waters remains unclear.In the present study,chemical composition of sour water DOMs(especially DOS)was investigated using fluorescence spectroscopy(excitation-emission matrix,EEM)and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS)and high-resolution Orbitrap MS.The GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process,while compounds with high hydrophilicity and humification degree were found to be more recalcitrant.The Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated compounds.However,the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms,particularly in the form of highly unsaturated and aromatic compounds.The Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates,disulfide bonds,thioethers.Understanding the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment. 展开更多
关键词 Molecular transformation Dissolved organic sulfur Stripping process Refinery sourwater Orbitrap MS
下载PDF
Performance Evaluation of Low-Carbon and Clean Transformation of China’s Coal Economy
3
作者 Liangfeng Zhu 《Journal of Environmental Science and Engineering(B)》 2024年第1期21-38,共18页
In China,the oversupply of coal occurred in 2009,and from that year onwards,China’s coal economy began a low-carbon and clean transformation.Evaluating transformation performance is the research goal of this paper.Th... In China,the oversupply of coal occurred in 2009,and from that year onwards,China’s coal economy began a low-carbon and clean transformation.Evaluating transformation performance is the research goal of this paper.The data collection for this paper includes data on deep processing of Chinese coal products from 2009 to 2020,as well as data on asset structure evolution and financial performance of 34 listed companies in the Chinese coal mining.Entropy value method is used to calculate the entropy value of low-carbon transformation,and the regression analysis is used to study the performance of cleaner transformation,the conclusion is as follows:(1)From 2009 to 2020,in China’s total energy consumption,coal consumption accounted for 71.6%in 2009 and 56.8%in 2020,the goals set by the state have been achieved.(2)The national goal of reducing the proportion of coal consumption and reducing carbon emissions has forced the transformation of deep processing of coal products.The transformation of coal enterprises towards low-carbon and clean production has achieved remarkable results.(3)From 2009 to 2020,the non coal industry income of 34 listed companies in China’s coal mining industry increased by 8.21%annually.At the same time,the asset structure was adjusted,and nearly 80%of the asset structure evolution showed an orderly development trend.(4)The regression analysis results show that the entropy value of coal deep processing products and the entropy value of asset structure adjustment are significantly related to transformation performance.The paper proposes to summarize the successful experience of China’s coal energy economic transformation,lay a foundation for achieving the carbon peak and carbon neutral goals in the future,further increase the intensity of coal deep processing,increase the proportion of clean energy in total energy consumption,and strive to control asset operation towards the goal of increasing the proportion of non coal industry income. 展开更多
关键词 Coal economy low-carbon and clean transformation deep processing of coal evolution of asset structure performance appraisal
下载PDF
Phosphorus speciation,transformation and benthic processes with implications for environmental impacts in the aquaculture area of Rushan Bay
4
作者 Yao Feng Jun Liu +4 位作者 Aijun Zhang Yibin Wang Lu Wang Zongqing Lv Xiangbin Ran 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第8期99-112,共14页
Phosphorus(P)is an essential nutrient for many organisms in the ocean,which plays a central role in the stability of ecosystems and the evolution of the environment.The distribution,occurrence and source-sink process ... Phosphorus(P)is an essential nutrient for many organisms in the ocean,which plays a central role in the stability of ecosystems and the evolution of the environment.The distribution,occurrence and source-sink process of P in offshore waters are highly influenced by mariculture activities.P transformation in water-sediment system is the key process in P cycling,however,the mechanism is poorly documented in the coastal sea which is influenced by human activities.Based on the comprehensive surveys in the adjacent waters outside Rushan Bay in May,July and August 2014 and February 2015,the form and transformation of P in the suspended particulate matter(SPM)and surface sediment were analyzed.The results showed that contents of total P,authigenic P and organic P of SPM increased with the increase in distance from the shoreline off Rushan Bay,and the detrital-P decreased.The partition coefficient of P between water and SPM was related to the chemical activity of different forms of P,and a higher reactivity of inorganic P associated with SPM was observed.Hypoxia induced by mariculture changes the distribution and morphological composition of P in SPM and sediment in this typical aquaculture area,which can result in a conversion of sink to source of P in the sediment,thereby having a significant impact on the regional nutrient budget and associated with eutrophication. 展开更多
关键词 phosphorus speciation transformation benthic process AQUACULTURE Rushan Bay
下载PDF
Effects of chimeric intron on the epithelial-mesenchymal transformation of non-small cell lung cancer PC-9
5
作者 Liang Liao Guo-Hui Yang 《Journal of Hainan Medical University》 2021年第2期1-5,共5页
Objective:To investigate the effects of Intron on the EMT capability of non-small cell lung cancer cell line PC-9.Methods:Firstly,using the psiCHECK-2 plasmid as a basic framework to construct the recombinant plasmid ... Objective:To investigate the effects of Intron on the EMT capability of non-small cell lung cancer cell line PC-9.Methods:Firstly,using the psiCHECK-2 plasmid as a basic framework to construct the recombinant plasmid of psiCHECK-2-Intron dual-luciferase reporter gene;secondly,the psiCHECK-2-Intron and psiCHECK-2 were transfected into PC-9 cells respectively.The migration and invasion abilities of PC-9 cells were analyzed by Matrigel assay.The expression changes of EMT related hallmarks,including N-cadherin,β-catenin and snail,were detected by qRT-PCR and Western Blotting.Results:Compared with the control group,the migration and invasion abilities of PC-9 cells in Intron group significantly decreased(p<0.001).The expression of N-cadherin,β-catenin and snail also down-regulated(p<0.001).Conclusion:The introns could inhibit the EMT of PC-9 cells. 展开更多
关键词 Chimeric intron PC-9 cell line Dual-fluorescent protein reporter gene Non-small cell lung cancer(NSCLC) epithelial-mesenchymal transformation(EMT)
下载PDF
Application of fast wavelet transformation in signal processing of MEMS gyroscope 被引量:6
6
作者 吉训生 王寿荣 许宜申 《Journal of Southeast University(English Edition)》 EI CAS 2006年第4期510-513,共4页
Decomposition and reconstruction of Mallat fast wavelet transformation (WT) is described. A fast algorithm, which can greatly decrease the processing burden and can be very easy for hardware implementation in real-t... Decomposition and reconstruction of Mallat fast wavelet transformation (WT) is described. A fast algorithm, which can greatly decrease the processing burden and can be very easy for hardware implementation in real-time, is analyzed. The algorithm will no longer have the processing of decimation and interpolation of usual WT. The formulae of the decomposition and the reconstruction are given. Simulation results of the MEMS (micro-electro mechanical systems) gyroscope drift signal show that the algorithm spends much less processing time to finish the de-noising process than the usual WT. And the de-noising effect is the same. The fast algorithm has been implemented in a TMS320C6713 digital signal processor. The standard variance of the gyroscope static drift signal decreases from 78. 435 5 (°)/h to 36. 763 5 (°)/h. It takes 0. 014 ms to process all input data and can meet the real-time analysis of signal. 展开更多
关键词 wavelet transformation signal processing GYROSCOPE THRESHOLD
下载PDF
基于Swin Transformer的沥青路面病害分类检测研究 被引量:1
7
作者 郭晨 杨玉龙 +1 位作者 左琛 杨冰鑫 《计算机测量与控制》 2024年第2期114-121,共8页
针对传统卷积神经网络模型在沥青路面病害检测中识别长距离裂缝结构能力不足以及面临的精度局限问题,引入Swin Transformer模型进行沥青路面病害分类研究;首先对于路面检测车采集到的沥青路面扫描图像对比度低的问题,使用直方图均衡技... 针对传统卷积神经网络模型在沥青路面病害检测中识别长距离裂缝结构能力不足以及面临的精度局限问题,引入Swin Transformer模型进行沥青路面病害分类研究;首先对于路面检测车采集到的沥青路面扫描图像对比度低的问题,使用直方图均衡技术处理图像,增加图像可视化效果;其次,选取3种经典卷积神经网络模型作为对比模型,并在训练过程中采用更换损失函数,调整预训练模型等手段解决过拟合问题;并选用准确率、查全率、F1-score作为评价指标;在最终实验结果中Swin Transformer识别准确率达到了80.6%,F1-score达到了0.776,不仅在整体分类准确率上超越了传统CNN模型,并且对具有长距离特征结构的病害方面具有更高的识别准确率,同时具有良好的可靠性。 展开更多
关键词 Swin transformer 路面病害检测 卷积神经网络 图像分类 图像处理
下载PDF
基于Transformer的司法文书命名实体识别方法
8
作者 王颖洁 张程烨 +1 位作者 白凤波 汪祖民 《计算机科学》 CSCD 北大核心 2024年第S01期113-121,共9页
命名实体识别是自然语言处理领域的关键任务之一,是实现下游任务的基础。目前针对司法领域的相关研究相对较少,司法系统的信息化和智能化转型仍有许多问题亟需解决。相比其他领域的文本,司法文书存在专业性强、语料资源少等局限,导致现... 命名实体识别是自然语言处理领域的关键任务之一,是实现下游任务的基础。目前针对司法领域的相关研究相对较少,司法系统的信息化和智能化转型仍有许多问题亟需解决。相比其他领域的文本,司法文书存在专业性强、语料资源少等局限,导致现有的司法文书识别结果较低。因此,从以下3方面开展研究:首先,提出了一种多标签层级迭代的文本标注方式,可以对原始司法文书文本进行自动化标注,同时有效地提升司法文书命名实体识别任务的实体识别效果;其次,提出了一种交融式的Transformer神经网络模型,对汉字固有属性的深层特征进行了充分利用,用于对司法文书进行命名实体识别;最后,对所提出的标注方法和模型与其他神经网络模型进行了对比实验。所提出的文本标注方式可以较为准确地实现司法文书的标注任务;同时,所提出的模型在通用数据集中相对于对照模型有较大的提高,并在司法领域数据集中取得了良好的效果。 展开更多
关键词 自然语言处理 数据标注 transformer模型 深度学习 司法信息化
下载PDF
北京大学-北海道大学新一代物质转换工程共同研究室(Peking University -Hokkaido UniversityJoint Lab.on Next Generation Process forMaterial Transformation)研究室及博士后招收介绍
9
作者 席振峰 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 1999年第S1期545-545,共1页
关键词 transformation 研究室 转换工 北京大学 博士后工作 博士后研究人员 日本北海道 大学化学 process 过渡金属有机化合物
下载PDF
规则压缩模型和灵活架构的Transformer加速器设计
10
作者 姜小波 邓晗珂 +1 位作者 莫志杰 黎红源 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第3期1079-1088,共10页
基于注意力机制的Transformer模型具有优越的性能,设计专用的Transformer加速器能大幅提高推理性能以及降低推理功耗。Transformer模型复杂性包括数量上和结构上的复杂性,其中结构上的复杂性导致不规则模型和规则硬件之间的失配,降低了... 基于注意力机制的Transformer模型具有优越的性能,设计专用的Transformer加速器能大幅提高推理性能以及降低推理功耗。Transformer模型复杂性包括数量上和结构上的复杂性,其中结构上的复杂性导致不规则模型和规则硬件之间的失配,降低了模型映射到硬件的效率。目前的加速器研究主要聚焦在解决模型数量上的复杂性,但对如何解决模型结构上的复杂性研究得不多。该文首先提出规则压缩模型,降低模型的结构复杂度,提高模型和硬件的匹配度,提高模型映射到硬件的效率。接着提出一种硬件友好的模型压缩方法,采用规则的偏移对角权重剪枝方案和简化硬件量化推理逻辑。此外,提出一个高效灵活的硬件架构,包括一种以块为单元的权重固定脉动运算阵列,同时包括一种准分布的存储架构。该架构可以高效实现算法到运算阵列的映射,同时实现高效的数据存储效率和降低数据移动。实验结果表明,该文工作在性能损失极小的情况下实现93.75%的压缩率,在FPGA上实现的加速器可以高效处理压缩后的Transformer模型,相比于中央处理器(CPU)和图形处理器(GPU)能效分别提高了12.45倍和4.17倍。 展开更多
关键词 自然语音处理 transformER 模型压缩 硬件加速器 机器翻译
下载PDF
基于语言和视觉融合Transformer的指代图像分割
11
作者 段勇 刘铁 《传感技术学报》 CAS CSCD 北大核心 2024年第7期1193-1201,共9页
针对指代图像分割任务中存在语言表达歧义、多模态特征对齐不充分、对图像整体理解不全面等问题,提出一种基于Transformer特征融合与对齐的多模态深度学习模型。该模型使用优化的Darknet53图像特征提取骨干网络,加强了对全局特征理解能... 针对指代图像分割任务中存在语言表达歧义、多模态特征对齐不充分、对图像整体理解不全面等问题,提出一种基于Transformer特征融合与对齐的多模态深度学习模型。该模型使用优化的Darknet53图像特征提取骨干网络,加强了对全局特征理解能力。使用了卷积神经网络结构、双向门控循环单元Bi-GRU结构和自注意力机制相互结合的语言特征提取结构,挖掘深层次语义特征,消除语言表达的歧义性。构建了基于Transformer的特征对齐结构,以提升模型的分割细节和分割精度。最后,采用平均的交并比mIoU和在不同阈值的识别精度作为模型评估指标,通过实验证明所提模型可以充分融合多模态的特征,理解多模态特征的深层语义信息,模型识别结果更加准确。 展开更多
关键词 深度学习 指代图像分割 自然语言处理 注意力机制 transformer模型
下载PDF
结合Transformer与生成对抗网络的水下图像增强算法
12
作者 袁红春 张波 程心 《红外技术》 CSCD 北大核心 2024年第9期975-983,共9页
由于水下环境的多样性和光在水中受到的散射及选择性吸收作用,采集到的水下图像通常会产生严重的质量退化问题,如颜色偏差、清晰度低和亮度低等,为解决以上问题,本文提出了一种基于Transformer和生成对抗网络的水下图像增强算法。以生... 由于水下环境的多样性和光在水中受到的散射及选择性吸收作用,采集到的水下图像通常会产生严重的质量退化问题,如颜色偏差、清晰度低和亮度低等,为解决以上问题,本文提出了一种基于Transformer和生成对抗网络的水下图像增强算法。以生成对抗网络为基础架构,结合编码解码结构、基于空间自注意力机制的全局特征建模Transformer模块和通道级多尺度特征融合Transformer模块构建了TGAN(generative adversarial network with transformer)网络增强模型,重点关注水下图像衰减更严重的颜色通道和空间区域,有效增强了图像细节并解决了颜色偏差问题。此外,设计了一种结合RGB和LAB颜色空间的多项损失函数,约束网络增强模型的对抗训练。实验结果表明,与CLAHE(contrast limited adaptive histogram equalization)、UDCP(underwater dark channel prior)、UWCNN(underwater based on convolutional neural network)、FUnIE-GAN(fast underwater image enhancement for improved visual perception)等典型水下图像增强算法相比,所提算法增强后的水下图像在清晰度、细节纹理和色彩表现等方面都有所提升,客观评价指标如峰值信噪比、结构相似性和水下图像质量度量的平均值分别提升了5.8%、1.8%和3.6%,有效地提升了水下图像的视觉感知效果。 展开更多
关键词 图像处理 水下图像增强 transformER 生成对抗网络 多项损失函数
下载PDF
Unscented Transformation Based Robust Kalman Filter and Its Applications in Fermentation Process 被引量:12
13
作者 王建林 冯絮影 +1 位作者 赵利强 于涛 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2010年第3期412-418,共7页
State estimation is the precondition and foundation of a bioprocess monitoring and optimal control. However,there are many difficulties in dealing with a non-linear system,such as the instability of process, un-modele... State estimation is the precondition and foundation of a bioprocess monitoring and optimal control. However,there are many difficulties in dealing with a non-linear system,such as the instability of process, un-modeled dynamics,parameter sensitivity,etc.This paper discusses the principles and characteristics of three different approaches,extended Kalman filters,strong tracking filters and unscented transformation based Kalman filters.By introducing the unscented transformation method and a sub-optimal fading factor to correct the prediction error covariance,an improved Kalman filter,unscented transformation based robust Kalman filter,is proposed. The performance of the algorithm is compared with the strong tracking filter and unscented transformation based Kalman filter and illustrated in a typical case study for glutathione fermentation process.The results show that the proposed algorithm presents better accuracy and stability on the state estimation in numerical calculations. 展开更多
关键词 robust Kalman filter unscented transformation fermentation process nonlinear system
下载PDF
基于TF-IDF和多头注意力Transformer模型的文本情感分析 被引量:7
14
作者 高佳希 黄海燕 《华东理工大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第1期129-136,共8页
文本情感分析旨在对带有情感色彩的主观性文本进行分析、处理、归纳和推理,是自然语言处理中一项重要任务。针对现有的计算方法不能充分处理复杂度和混淆度较高的文本数据集的问题,提出了一种基于TF-IDF(Term Frequency-Inverse Documen... 文本情感分析旨在对带有情感色彩的主观性文本进行分析、处理、归纳和推理,是自然语言处理中一项重要任务。针对现有的计算方法不能充分处理复杂度和混淆度较高的文本数据集的问题,提出了一种基于TF-IDF(Term Frequency-Inverse Document Frequency)和多头注意力Transformer模型的文本情感分析模型。在文本预处理阶段,利用TF-IDF算法对影响文本情感倾向较大的词语进行初步筛选,舍去常见的停用词及其他文本所属邻域对文本情感倾向影响较小的专有名词。然后,利用多头注意力Transformer模型编码器进行特征提取,抓取文本内部重要的语义信息,提高模型对语义的分析和泛化能力。该模型在多领域、多类型评论语料库数据集上取得了98.17%的准确率。 展开更多
关键词 文本情感分析 自然语言处理 多头注意力机制 TF-IDF算法 transformer模型
下载PDF
Recent developments in selective laser processes for wearable devices 被引量:1
15
作者 Youngchan Kim Eunseung Hwang +3 位作者 Chang Kai Kaichen Xu Heng Pan Sukjoon Hong 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第4期517-547,共31页
Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication methods.Lasers have long been used to d... Recently,the increasing interest in wearable technology for personal healthcare and smart virtual/augmented reality applications has led to the development of facile fabrication methods.Lasers have long been used to develop original solutions to such challenging technological problems due to their remote,sterile,rapid,and site-selective processing of materials.In this review,recent developments in relevant laser processes are summarized under two separate categories.First,transformative approaches,such as for laser-induced graphene,are introduced.In addition to design optimization and the alteration of a native substrate,the latest advances under a transformative approach now enable more complex material compositions and multilayer device configurations through the simultaneous transformation of heterogeneous precursors,or the sequential addition of functional layers coupled with other electronic elements.In addition,the more conventional laser techniques,such as ablation,sintering,and synthesis,can still be used to enhance the functionality of an entire system through the expansion of applicable materials and the adoption of new mechanisms.Later,various wearable device components developed through the corresponding laser processes are discussed,with an emphasis on chemical/physical sensors and energy devices.In addition,special attention is given to applications that use multiple laser sources or processes,which lay the foundation for the all-laser fabrication of wearable devices. 展开更多
关键词 Selective laser process Wearable device transformative approach Laser-induced graphene Ablation SINTERING Synthesis
下载PDF
PCA weight and Johnson transformation based alarm threshold optimization in chemical processes 被引量:4
16
作者 Wende Tian Guixin Zhang +1 位作者 Xiang Zhang Yuxi Dong 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第8期1653-1661,共9页
To alleviate the heavy load of massive alarm on operators, alarm threshold in chemical processes was optimized with principal component analysis(PCA) weight and Johnson transformation in this paper. First, few variabl... To alleviate the heavy load of massive alarm on operators, alarm threshold in chemical processes was optimized with principal component analysis(PCA) weight and Johnson transformation in this paper. First, few variables that have high PCA weight factors are chosen as key variables. Given a total alarm frequency to these variables initially, the allowed alarm number for each variable is determined according to their sampling time and weight factors. Their alarm threshold and then control limit percentage are determined successively. The control limit percentage of non-key variables is determined with 3σ method alternatively. Second, raw data are transformed into normal distribution data with Johnson function for all variables before updating their alarm thresholds via inverse transformation of obtained control limit percentage. Alarm thresholds are optimized by iterating this process until the calculated alarm frequency reaches standard level(normally one alarm per minute). Finally,variables and their alarm thresholds are visualized in parallel coordinate to depict their variation trends concisely and clearly. Case studies on a simulated industrial atmospheric-vacuum crude distillation demonstrate that the proposed alarm threshold optimization strategy can effectively reduce false alarm rate in chemical processes. 展开更多
关键词 Alarm threshold Chemical process PCA Johnson transformation Variable weight
下载PDF
一种基于安全多方计算的快速Transformer安全推理方案 被引量:1
17
作者 刘伟欣 管晔玮 +3 位作者 霍嘉荣 丁元朝 郭华 李博 《计算机研究与发展》 EI CSCD 北大核心 2024年第5期1218-1229,共12页
Transformer模型在自然语言处理、计算机视觉等众多领域得到了广泛应用,并且有着突出的表现.在Transformer的推理应用中用户的数据会被泄露给模型提供方.随着数据隐私问题愈发得到公众的关注,上述数据泄露问题引发了学者们对Transforme... Transformer模型在自然语言处理、计算机视觉等众多领域得到了广泛应用,并且有着突出的表现.在Transformer的推理应用中用户的数据会被泄露给模型提供方.随着数据隐私问题愈发得到公众的关注,上述数据泄露问题引发了学者们对Transformer安全推理的研究,使用安全多方计算(secure multi-party computation,MPC)实现Transformer模型的安全推理是当前的一个研究热点.由于Transformer模型中存在大量非线性函数,因此使用MPC技术实现Transformer安全推理会造成巨大的计算和通信开销.针对Transformer安全推理过程中开销较大的Softmax注意力机制,提出了2种MPC友好的注意力机制Softmax freeDiv Attention和2Quad freeDiv Attention.通过将Transformer模型中的Softmax注意力机制替换为新的MPC友好的注意力机制,同时结合激活函数GeLU的替换以及知识蒸馏技术,提出了一个MPC友好的Transformer转换框架,通过将Transformer模型转化为MPC友好的Transformer模型,提高Transformer安全推理的效率.在局域网环境下使用安全处理器(secure processing unit,SPU)提供的隐私计算协议,基于所提出的MPC友好的Transformer转换框架,在SST-2上使用Bert-Base进行安全推理.测试结果表明,在保持推理准确率与无近似模型一致的情况下,安全推理计算效率提高2.26倍. 展开更多
关键词 安全推理 transformER 安全多方计算 安全处理器 知识蒸馏
下载PDF
Mechanism of Phase Transformation and Formation of Barium Hexafer rite Doped with Rare-Earths in Sol-Gel Process 被引量:2
18
作者 甘树才 洪广言 +2 位作者 张军 车平 唐娟 《Journal of Rare Earths》 SCIE EI CAS CSCD 2003年第1期98-100,共3页
The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La 3+ were studied by chemical p hase analysis, X-ray diffraction and infrared spectrometry an... The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La 3+ were studied by chemical p hase analysis, X-ray diffraction and infrared spectrometry analysis. The expe rimental results show that phase transformation reactions of FeCO 3, Fe 2O 3 and BaFe 2O 4, barium hexaferrite and γ-Fe 2O 3 take place in the heat tr eatment of gel. While the doping lanthanide ion replace barium ion, an equivalen t quantity of Fe 3+ are reduced to Fe 2+ to maintain the charge equili brium. 展开更多
关键词 chemical materials barium hexafettite doped rare earths sol-gel process phase transformation MECHANISM
下载PDF
Role of reactive oxygen species in epithelial-mesenchymal transition and apoptosis of human lens epithelial cells
19
作者 Rui-Hua Jing Cong-Hui Hu +1 位作者 Tian-Tian Qi Bo Ma 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2023年第12期1935-1941,共7页
AIM:To investigate the role of reactive oxygen species(ROS)in epithelial–mesenchymal transition(EMT)and apoptosis of human lens epithelial cells(HLECs).METHODS:Flow cytometry was used to assess ROS production after t... AIM:To investigate the role of reactive oxygen species(ROS)in epithelial–mesenchymal transition(EMT)and apoptosis of human lens epithelial cells(HLECs).METHODS:Flow cytometry was used to assess ROS production after transforming growth factorβ2(TGF-β2)induction.Apoptosis of HLECs after H_(2)O_(2) and TGF-β2 interference with or without ROS scavenger N-acetylcysteine(NAC)were assessed by flow cytometry.The corresponding protein expression levels of the EMT markerα-smooth muscle actin(α-SMA),the extracellular matrix(ECM),marker fibronectin(Fn),and apoptosis-associated proteins were detected by using Western blotting in the presence of an ROS scavenger(NAC).Wound-healing and Transwell assays were used to assess the migration capability of HLECs.RESULTS:TGF-β2 stimulates ROS production within 8h in HLECs.Additionally,TGF-β2 induced HLECs cell apoptosis,EMT/ECM synthesis protein markers expression,and pro-apoptotic proteins production;nonetheless,NAC treatment prevented these responses.Similarly,TGF-β2 promoted HLECs cell migration,whereas NAC inhibited cell migration.We further determined that although ROS initiated apoptosis,it only induced the accumulation of the EMT markerα-SMA protein,but not COL-1 or Fn.CONCLUSION:ROS contribute to TGF-β2-induced EMT/ECM synthesis and cell apoptosis of HLECs;however,ROS alone are not sufficient for EMT/ECM synthesis. 展开更多
关键词 human lens epithelial cells epithelial-mesenchymal transition transforming growth factorβ2 reactive oxygen species APOPTOSIS
下载PDF
STATE TRANSFORMATION PROCESSES FOR FREE-FLOATING THREE-LINK PLANAR ROBOTS 被引量:1
20
作者 XuMingtao XuYangsheng JamesK.Mills 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2004年第2期166-169,共4页
The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF trans... The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF transformation processes as an alternative to them-DOF transformation process. Two static state transformation processes are studied in detail.First, a single-DOF transformation process is established using a newly defined concept, referred toas transformation planning, and the definite integral of conservation of angular momentum. Second,the governing equation of the single-DOF transformation process is established using the dynamicequations of motion of the robot. This allows the joint torques to be computed to effect the statetransformation. Finally, an extension of the single-DOF transformation process is proposed to extendthe application of this proposed transformation methodology to create a transformation net whichallows the reconfiguration of a robot from one state to many other possible states. 展开更多
关键词 Planar robot Static state Single-DOF transformation process n-elementtransformation net
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部