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DNA Methylation Variation Is Identified in Monozygotic Twins Discordant for Congenital Heart Diseases
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作者 Shuliang Xia Huikang Tao +10 位作者 Shixin Su Xinxin Chen Li Ma Jianru Li Bei Gao Xumei Liu Lei Pi Jinqing Feng Fengxiang Li Jia Li Zhiwei Zhang 《Congenital Heart Disease》 SCIE 2024年第2期247-256,共10页
Aims:Multiple genes and environmental factors are known to be involved in congenital heart disease(CHD),but epigenetic variation has received little attention.Monozygotic(MZ)twins with CHD provide a unique model for e... Aims:Multiple genes and environmental factors are known to be involved in congenital heart disease(CHD),but epigenetic variation has received little attention.Monozygotic(MZ)twins with CHD provide a unique model for exploring this phenomenon.In order to investigate the potential role of Deoxyribonucleic Acid(DNA)methyla-tion in CHD pathogenesis,the present study examined DNA methylation variation in MZ twins discordant for CHD,especially ventricular septal defect(VSD).Methods and Results:Using genome-wide DNA methylation profiles,we identified 4004 differentially methylated regions(DMRs)in 18 MZ twin pairs discordant for CHD,and 2826 genes were identified.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis revealed a list of CHD-associated pathways.To further investigate the role of DNA methylation in VSD,data from 7 pairs of MZ twins with VSD were analyzed.We identified 1614 DMRs corresponding to 1443 genes associated with arrhythmogenic right ventricular cardiomyopathy,cyclic guanosine monopho-sphate-protein kinase G(cGMP-PKG)signaling pathway by KEGG analysis,and cell-cell adhesion,calcium ion transmembrane transport by GO analysis.A proportion of DMR-associated genes were involved in calcium signaling pathways.The methylation changes of calcium signaling genes might be related to VSD pathogenesis.Conclusion:CHD is associated with differential DNA methylation in MZ twins.CHD may be etiologically linked to DNA methylation,and methylation of calcium signaling genes may be involved in the development of VSD. 展开更多
关键词 Congenital heart disease monozygotic twins methylation modification EPIGENETICS
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Fetoscopic Laser Photocoagulation for Twin-Twin Transfusion Syndrome in a Dizygotic Monochorionic Twins
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作者 Huirong Tang Chenyan Dai +6 位作者 Huijun Li Xiangyu Zhu Honglei Duan Xian Xiao Liang Jin Jie Li Mingming Zheng 《Maternal-Fetal Medicine》 CAS CSCD 2024年第2期110-114,共5页
To editor:Monochorionicity was traditionally considered indicative of monozygosity.However,recent years have witnessed the emergence of several noteworthy instances of monochorionic dizygotic(MCDZ)twins in clinical pr... To editor:Monochorionicity was traditionally considered indicative of monozygosity.However,recent years have witnessed the emergence of several noteworthy instances of monochorionic dizygotic(MCDZ)twins in clinical practice.In 2000,Viëtor et al.1 documented the initial established case of MCDZ twins.Subsequent studies have further documented this unconventional twinning phenomenon.2,3 The recognized complications associated with monochorionic monozygotic pregnancies,including twin-twin transfusion syndrome(TTTS),twin anemia–polycythemia sequence(TAPS),selective intrauterine growth restriction(sIUGR),congenital malformations,and intrauterine fetal death,could also manifest in MCDZ pregnancies.4,5 In this correspondence,we presented an extremely rare case of TTTS in a dizygotic monochorionic diamniotic twin gestation successfully treated with fetoscopic laser photocoagulation.The patients’permission to publish was obtained. 展开更多
关键词 TRANSFUSION TWIN EDITOR
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Origin of nucleation and growth of extension twins in grains unsuitably oriented for twinning during deformation of Mg-1%Al
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作者 Biaobiao Yang Javier LLorca 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第3期1186-1203,共18页
A large number of anomalous extension twins,with low or even negative twinning Schmid factors,were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction... A large number of anomalous extension twins,with low or even negative twinning Schmid factors,were found to nucleate and grow in a strongly textured Mg-1Al alloy during tensile deformation along the extruded direction.The deformation mechanisms responsible for this behaviour were investigated through in-situ electron back-scattered diffraction,grain reference orientation deviation,and slip trace-modified lattice rotation.It was found that anomalous extension twins nucleated mainly at the onset of plastic deformation at or near grain boundary triple junctions.They were associated with the severe strain incompatibility between neighbour grains as a result from the differentbasal slip-induced lattice rotations.Moreover,the anomalous twins were able to grow with the applied strain due to the continuous activation ofbasal slip in different neighbour grains,which enhanced the strain incompatibility.These results reveal the complexity of the deformation mechanisms in Mg alloys at the local level when deformed along hard orientations. 展开更多
关键词 Magnesium Extension twinning In-situ electron back-scattered diffraction basal slip Deformation mechanisms.
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Exploring Alternatives to Create Digital Twins from and for Process Simulation
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作者 Jaime Barbero-Sánchez Alicia Megía-Ortega +1 位作者 Víctor R.Ferro Jose-Luis Valverde 《Journal of Computer Science Research》 2024年第1期16-30,共15页
In this work,Digital Twins based on Neural Networks for the steady state production of styrene were generated.Thus,both the Aspen Technology AI Model Builder(alternative 1)and a homemade MS Excel VBA code connected to... In this work,Digital Twins based on Neural Networks for the steady state production of styrene were generated.Thus,both the Aspen Technology AI Model Builder(alternative 1)and a homemade MS Excel VBA code connected to Aspen HYSYS and Aspen Plus(alternative 2)were used with this same aim.The raw data used for generating the Digital Twins were obtained from process simulations using Aspen HYSYS and/or Aspen Plus,which were connected through a recycle-like stream via automation for solving the entire simulation flowsheet.Aspen HYSYS was used for solving the pre-heating,reaction,and stabilization sections of the process whereas Aspen Plus ensured the computing of the separation and purification columns.Both alternatives led to an excellent prediction showing the capability of creating Digital Twins from and for process simulation. 展开更多
关键词 Digital Twin Aspen Hybrid Model Builder Aspen HYSYS Aspen Plus Automation MS Excel-VBA
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Promoting hybrid twins structure to reduce yield asymmetry of rolled AZ31 plates by combining side-rolling and torsion 被引量:1
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作者 Bo Song Meng Wang +4 位作者 Ruolan Shi Zhiwen Du Ning Guo Fang Wang Shengfeng Guo 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第6期2096-2105,共10页
In this work,an as-rolled AZ31 square bar with c-axis//ND(normal direction)texture was used.Side-rolling and reciprocating torsion were performed to treat the bar.Microstructure evolution and tensile-compressive prope... In this work,an as-rolled AZ31 square bar with c-axis//ND(normal direction)texture was used.Side-rolling and reciprocating torsion were performed to treat the bar.Microstructure evolution and tensile-compressive properties were investigated in detail.Initial rolled AZ31 bar exhibits a large yield asymmetry along the rolling direction(RD).Reciprocating torsion can generate extension twins to introduce twin boundaries and twin-texture.The twin structure can reduce yield asymmetry.However,only limited regions in the rolled AZ31 bar can be twinned during torsion.Pre-side-rolling along the transverse direction(TD)can generate two texture components(c-axis//TD texture and c-axis//ND texture)by introducing profuse{10–12}twins.Such dual texture components help increase the regions which are favorable for twinning during torsion.Finally,combining side-rolling and reciprocating torsion generates hybrid{10–12}twins structure on the entire cross-section,resulting in a remarkably low yield asymmetry.The relevant mechanisms were discussed in detail. 展开更多
关键词 AZ31 Square section TORSION Hybrid twins Orientation Yield asymmetry
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Design and Implementation of Secure and Reliable Information Interaction Architecture for Digital Twins
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作者 Qian Wang Wanwan Wu +3 位作者 Liping Qian Yiming Cai Jiang Qian Limin Meng 《China Communications》 SCIE CSCD 2023年第2期79-93,共15页
In order to improve the comprehensive defense capability of data security in digital twins(DTs),an information security interaction architecture is proposed in this paper to solve the inadequacy of data protection and... In order to improve the comprehensive defense capability of data security in digital twins(DTs),an information security interaction architecture is proposed in this paper to solve the inadequacy of data protection and transmission mechanism at present.Firstly,based on the advanced encryption standard(AES)encryption,we use the keystore to expand the traditional key,and use the digital pointer to avoid the key transmission in a wireless channel.Secondly,the identity authentication technology is adopted to ensure the data integrity,and an automatic retransmission mechanism is added for the endogenous properties of the wireless channel.Finally,the software defined radio(SDR)platform composed of universal software radio peripheral(USRP)and GNU radio is used to simulate the data interaction between the physical entity and the virtual entity.The numerical results show that the DTs architecture can guarantee the encrypted data transmitted completely and decrypted accurately with high efficiency and reliability,thus providing a basis for intelligent and secure information interaction for DTs in the future. 展开更多
关键词 digital twins AES encryption digital pointer identity authentication automatic retransmission SDR
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Modeling Methods of 3D Model in Digital Twins
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作者 Ruijun Liu Haisheng Li Zhihan Lv 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第8期985-1022,共38页
To understand the current application and development of 3D modeling in Digital Twins(DTs),abundant literatures on DTs and 3D modeling are investigated by means of literature review.The transition process from 3D mode... To understand the current application and development of 3D modeling in Digital Twins(DTs),abundant literatures on DTs and 3D modeling are investigated by means of literature review.The transition process from 3D modeling to DTs modeling is analyzed,as well as the current application of DTs modeling in various industries.The application of 3D DTs modeling in the􀀀elds of smartmanufacturing,smart ecology,smart transportation,and smart buildings in smart cities is analyzed in detail,and the current limitations are summarized.It is found that the 3D modeling technology in DTs has broad prospects for development and has a huge impact on all walks of life and even human lifestyles.At the same time,the development of DTs modeling relies on the development and support capabilities of mature technologies such as Big Data,Internet of Things,Cloud Computing,Articial Intelligence,and game technology.Therefore,although some results have been achieved,there are still limitations.This work aims to provide a good theoretical support for the further development of 3D DTs modeling. 展开更多
关键词 Digital twins 3D modeling smart manufacturing smart city smart buildings
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Regional Economic Development Trend Prediction Method Based on Digital Twins and Time Series Network
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作者 Runguo Xu Xuehan Yu Xiaoxue Zhao 《Computers, Materials & Continua》 SCIE EI 2023年第8期1781-1796,共16页
At present,the interpretation of regional economic development(RED)has changed from a simple evaluation of economic growth to a focus on economic growth and the optimization of economic structure,the improvement of ec... At present,the interpretation of regional economic development(RED)has changed from a simple evaluation of economic growth to a focus on economic growth and the optimization of economic structure,the improvement of economic relations,and the change of institutional innovation.This article uses the RED trend as the research object and constructs the RED index to conduct the theoretical analysis.Then this paper uses the attention mechanism based on digital twins and the time series network model to verify the actual data.Finally,the regional economy is predicted according to the theoretical model.The specific research work mainly includes the following aspects:1)This paper introduced the development status of research on time series networks and economic forecasting at home and abroad.2)This paper introduces the basic principles and structures of long and short-term memory(LSTM)and convolutional neural network(CNN),constructs an improved CNN-LSTM model combined with the attention mechanism,and then constructs a regional economic prediction index system.3)The best parameters of the model are selected through experiments,and the trained model is used for simulation experiment prediction.The results show that the CNN-LSTM model based on the attentionmechanism proposed in this paper has high accuracy in predicting regional economies. 展开更多
关键词 Regional economic development attention mechanism digital twins time series network
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On the strengthening and slip activity of Mg-3Al-1Zn alloy with pre-induced{1012¯}twins
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作者 Jie Kuang Yuqing Zhang +3 位作者 Xinpeng Du Jinyu Zhang Gang Liu Jun Sun 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第4期1292-1307,共16页
{1012¯}twins were introduced into the magnesium(Mg)plate AZ31 via pre-rolling along its transverse direction.The plates,both with and without the pre-induced{1012¯}twins,were subjected to uniaxial tension al... {1012¯}twins were introduced into the magnesium(Mg)plate AZ31 via pre-rolling along its transverse direction.The plates,both with and without the pre-induced{1012¯}twins,were subjected to uniaxial tension along different directions.Using crystal plasticity modeling,we found that the strengthening effect of the pre-induced{1012¯}twins on the macroscopic flow stress primarily arised from the increased slip resistance caused by the boundaries,rather than the orientation hardening due to the twinning reorientation(although the latter did make its contribution in some specific loading directions).Besides,the pre-existing{1012¯}twins were found,by both experiments and simulation,to promote the activity of prismatic and pyramidal<c+a>in the parent matrix of the material.Further analysis showed that the enhanced non-basal slip activity is related to the{1012¯}twin boundaries’low micro Hall-Petch slope ratios of non-basal slips to basal slip.With the critical resolved shear stress(CRSS)obtained from crystal plasticity modeling and the orientation data from EBSD,a probability-based slip transfer model was proposed.The model predicts higher slip transfer probabilities and thus lower strain concentration tendencies at{1012¯}twin boundaries than that at grain boundaries,which agrees with the experimental observation that the strain localization was primarily associated with the latter.The present findings are helpful scientifically,in deepening our understanding of how the pre-induced{1012¯}twins affect the strength and slip activity of Mg alloys,and technologically,in guiding the design of the pre-strain protocol of Mg alloys. 展开更多
关键词 Mg alloy {1012¯}twins Strengthening Slip activity Micro Hall-Petch effect
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A spatiotemporal intelligent framework and experimental platform for urban digital twins
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作者 Jinxing HU Zhihan LV +5 位作者 Diping YUAN Bing HE Wenjiang CHEN Xiongfei YE Donghao LI Ge YANG 《Virtual Reality & Intelligent Hardware》 2023年第3期213-231,共19页
Backgrounds This work emphasizes the current research status of the urban Digital Twins to establish an intelligent spatiotemporal framework.A Geospatial Artificial Intelligent(GeoAI)system is developed based on the G... Backgrounds This work emphasizes the current research status of the urban Digital Twins to establish an intelligent spatiotemporal framework.A Geospatial Artificial Intelligent(GeoAI)system is developed based on the Geographic Information System and Artificial Intelligence.It integrates multi-video technology and Virtual City in urban Digital Twins.Methods Besides,an improved small object detection model is proposed:YOLOv5-Pyramid,and Siamese network video tracking models,namely MPSiam and FSSiamese,are established.Finally,an experimental platform is built to verify the georeferencing correction scheme of video images.Result The MultiplyAccumulate value of MPSiam is 0.5B,and that of ResNet50-Siam is 4.5B.Besides,the model is compressed by 4.8times.The inference speed has increased by 3.3 times,reaching 83 Frames Per Second.3%of the Average Expectation Overlap is lost.Therefore,the urban Digital Twins-oriented GeoAI framework established here has excellent performance for video georeferencing and target detection problems. 展开更多
关键词 Spatiotemporal intelligence Urban digital twins Geographic information system Artificial intelligence Small target detection
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Embryo-to-lamella transition of grain boundary twins in magnesium
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作者 Mariyappan Arul Kumar Irene J Beyerlein 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第12期4485-4497,共13页
A combined experimental and computational analysis is performed to investigate the less commonly studied embryo-to-lamella transition of deformation twins in magnesium. This work aims to understand the structural vari... A combined experimental and computational analysis is performed to investigate the less commonly studied embryo-to-lamella transition of deformation twins in magnesium. This work aims to understand the structural variables controlling the embryo-to-lamella transition from grain boundaries. Statistical analysis of hundreds of early-stage twins in the lightly deformed microstructure reveals a prevailing wedge shape,with a much thicker base along the grain boundary(GB) where they originate and a thinner tip terminating in the crystal. The analysis also shows that the GB base is super thick and identifies a minimum GB twin thickness among all early-stage twins that is about one micron. A crystal plasticity-based full-field model is employed to calculate the driving forces to migrate the boundary of a three-dimensional GB twin embryo. The stress analysis, considering a full range of embryo shapes and neighboring grain orientations, indicate that the twin embryo is most likely going to form a wedge shape when it first propagates. The calculations predict that the thickness of the embryo at the GB needs to be significantly larger than its length into the crystal in order to propagate into the crystal. The analysis finds that the more aligned the twin embryo variant is with basal slip in the neighboring grain, the thinner the twin embryo needed for propagation. 展开更多
关键词 MAGNESIUM Twin embryo Crystal plasticity Nucleation Grain neighbor
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Distributed Edge Cooperation and Data Collection for Digital Twins of Wide-Areas
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作者 Mancong Kang Xi Li +1 位作者 Hong Ji Heli Zhang 《China Communications》 SCIE CSCD 2023年第8期177-197,共21页
Digital twins for wide-areas(DT-WA)can model and predict the physical world with high fidelity by incorporating an artificial intelligence(AI)model.However,the AI model requires an energy-consuming updating process to... Digital twins for wide-areas(DT-WA)can model and predict the physical world with high fidelity by incorporating an artificial intelligence(AI)model.However,the AI model requires an energy-consuming updating process to keep pace with the dynamic environment,where studies are still in infancy.To reduce the updating energy,this paper proposes a distributed edge cooperation and data collection scheme.The AI model is partitioned into multiple sub-models deployed on different edge servers(ESs)co-located with access points across wide-area,to update distributively using local sensor data.To reduce the updating energy,ESs can choose to become either updating helpers or recipients of their neighboring ESs,based on sensor quantities and basic updating convergencies.Helpers would share their updated sub-model parameters with neighboring recipients,so as to reduce the latter updating workload.To minimize system energy under updating convergency and latency constraints,we further propose an algorithm to let ESs distributively optimize their cooperation identities,collect sensor data,and allocate wireless and computing resources.It comprises several constraint-release approaches,where two child optimization problems are solved,and designs a largescale multi-agent deep reinforcement learning algorithm.Simulation shows that the proposed scheme can efficiently reduce updating energy compared with the baselines. 展开更多
关键词 digital twin smart city multi-agent deep reinforcement learning resource allocation
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Integration of Digital Twins and Artificial Intelligence for Classifying Cardiac Ischemia
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作者 Mohamed Ammar Hamed Al-Raweshidy 《Journal on Artificial Intelligence》 2023年第1期195-218,共24页
Despite advances in intelligent medical care,difficulties remain.Due to its complicated governance,designing,planning,improving,and managing the cardiac system remains difficult.Oversight,including intelligent monitor... Despite advances in intelligent medical care,difficulties remain.Due to its complicated governance,designing,planning,improving,and managing the cardiac system remains difficult.Oversight,including intelligent monitoring,feedback systems,and management practises,is unsuccessful.Current platforms cannot deliver lifelong personal health management services.Insufficient accuracy in patient crisis warning programmes.No frequent,direct interaction between healthcare workers and patients is visible.Physical medical systems and intelligent information systems are not integrated.This study introduces the Advanced Cardiac Twin(ACT)model integrated with Artificial Neural Network(ANN)to handle real-time monitoring,decision-making,and crisis prediction.THINGSPEAK is used to create an IoT platform that accepts patient sensor data.Importing these data sets into MATLAB allows display and analysis.A myocardial ischemia research examined Health Condition Tracking’s(HCT’s)potential.In the case study,75%of the training sets(Xt),15%of the verified data,and 10%of the test data were used.Training set feature values(Xt)were given with the data.Training,Validation,and Testing accuracy rates were 99.9%,99.9%,and 99.9%,respectively.General research accuracy was 99.9%.The proposed HCT system and Artificial Neural Network(ANN)model gather historical and real-time data to manage and anticipate cardiac issues. 展开更多
关键词 Digital twin hybrid twin cardiac twin cardiac ischemia IoT healthcare AI artificial intelligence machine learning
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A generic framework for qualifications of digital twins in maintenance
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作者 Jie Liu Xingheng Liu +1 位作者 Jørn Vatn Shen Yin 《Journal of Automation and Intelligence》 2023年第4期196-203,共8页
Digital twins have emerged as a promising technology for maintenance applications,enabling organizations to simulate and monitor physical assets to improve their performance.In Operation and Maintenance(O&M),digit... Digital twins have emerged as a promising technology for maintenance applications,enabling organizations to simulate and monitor physical assets to improve their performance.In Operation and Maintenance(O&M),digital twin facilitates the diagnosis and prognosis of critical assets,forming the basis for smart maintenance planning and reducing downtime.However,there is a lack of standardized approaches for the qualifications of digital twins in maintenance,leading to low trustworthiness and limiting its application.This paper proposes a novel framework for the qualifications of digital twins in maintenance based on five pillars,namely fidelity,smartness,timeliness,integration,and standard compliance.We demonstrate the effectiveness of the framework through two case studies,showing how it can be implemented on digital twins for preventive maintenance and condition-based maintenance.Our proposed framework can help organizations across different industrial domains develop and implement digital twins in maintenance more effectively and efficiently,leading to significant benefits in terms of cost reduction,performance improvement,and sustainability. 展开更多
关键词 Digital twin QUALIFICATION Standardized approach Maintenance applications Maintenance models
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m^(6)AmTwins:基于深度学习和Twins网络的m^(6)A_(m)位点预测
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作者 贾建华 陈天 +1 位作者 吴跟强 孙明炜 《中国生物化学与分子生物学报》 CAS CSCD 北大核心 2023年第6期889-895,共7页
N6,2′-O-二甲基腺苷(m^(6)Am)是一种常见的RNA分子的可逆修饰。部分研究已经说明m^(6)Am对mRNA的影响,但现阶段对m^(6)Am的生物学功能探索仍不够。所以我们提出了m^(6)AmTwins,一种新的端到端双胞胎网络,将Transformer(自动编码器)和... N6,2′-O-二甲基腺苷(m^(6)Am)是一种常见的RNA分子的可逆修饰。部分研究已经说明m^(6)Am对mRNA的影响,但现阶段对m^(6)Am的生物学功能探索仍不够。所以我们提出了m^(6)AmTwins,一种新的端到端双胞胎网络,将Transformer(自动编码器)和双向门控循环单元(Bi-GRU)有机结合,简单利用RNA序列得到RNA的检测性。相比于现有的算法,本文亮点在于利用对比学习,构建新的损失函数来训练m^(6)AmTwins模型,提高了模型的泛化能力。基于Twins网络和简单编码方案,在两组正负比为1∶10的非平衡数据集下,其独立测试集上均取得了较好的结果,马修斯相关系数(MCC)分别得到0.53和0.545。同时,为增强m^(6)AmTwins模型的鲁棒性(robustness),本文在训练集上还进行了10折交叉验证,其MCC结果分别为0.562和0.567,说明该模型具有良好的泛化能力,可为生物医学在m^(6)Am上的研究提供一定的价值。 展开更多
关键词 N6 2′-O-二甲基腺苷 特征提取 深度学习 双胞胎网络
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一次大磁暴主相期间ENA氧与氢的分离及分布特征——TWINS卫星观测 被引量:2
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作者 胡荣璞 颜伟男 +1 位作者 马淑英 徐继生 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2017年第11期4364-4376,共13页
本文采用基于ENA(Energetic Neutral Atoms)次生电子起始脉冲高度分布,统计拟合分离中能段ENA两种主要成分氢和氧的方法,研发了实现ENA氢与氧分离的TWINS卫星原始数据处理软件;其中所需要的脉高分布模型,参照已有理论公式,利用TWINS(Two... 本文采用基于ENA(Energetic Neutral Atoms)次生电子起始脉冲高度分布,统计拟合分离中能段ENA两种主要成分氢和氧的方法,研发了实现ENA氢与氧分离的TWINS卫星原始数据处理软件;其中所需要的脉高分布模型,参照已有理论公式,利用TWINS(Two Wide-angle Imaging Neutral-atom Spectrometers)卫星标定数据进行拟合确定未知参数,再加以计算得到.将上述方法用于TWINS卫星实测数据,分离得到一次大磁暴主相期间ENA-H和ENA-O微分通量随观测视线的分布及其随主相增长的变化.分析发现:(1)ENA-H与ENA-O微分通量的强度和随观测视线的分布特征都有明显差别,从某种角度反映出ENA之源的O^+与H^+离子强度和分布之间的差异;(2)接近主相极大时,ENA-H有很强的低高度发射(LAE,Low Altitude Emission),出现在磁地方时午夜前极光和亚极光纬度区,意味着该区域较强的等离子片和环电流质子沉降,进入到外层基底以下较低高度大气层;而ENA-O则未有明显LAE产生;ENA-O强通量观测视线主要穿过广大环电流区,磁地方时主要在午夜之后以及黄昏前和黎明前后;(3)在磁暴主相快速增长期,ENA-O平均总通量持续增大,而ENA-H同步减小,ENA-O与ENA-H平均总通量的比率随环电流指数Dst绝对值的增大而大致成正比增长. 展开更多
关键词 ENA氢氧分离 中能段ENA 脉冲高度分布 twins卫星 磁暴环电流
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利用差分体像素CT由TWINS卫星ENA成像反演暴时环电流离子三维分布
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作者 颜伟男 马淑英 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2015年第7期2221-2234,共14页
本文将体像素CT方法应用于TWINS卫星高能中性原子立体成像数据,重建环电流离子通量强度三维分布.为了克服卫星ENA成像可能存在的仪器偏差造成反演误差增大甚至迭代发散无解的问题,发展了差分ENA体像素CT反演方法.采用环电流离子分布理... 本文将体像素CT方法应用于TWINS卫星高能中性原子立体成像数据,重建环电流离子通量强度三维分布.为了克服卫星ENA成像可能存在的仪器偏差造成反演误差增大甚至迭代发散无解的问题,发展了差分ENA体像素CT反演方法.采用环电流离子分布理论模型和实际卫星观测几何构形进行模拟检验,证明了该方法的可靠性和优越性.利用此方法分析2012年7月15日磁暴(min Dst=-133nT)主相期间TWINS两颗卫星的实测ENA数据(能量范围4keV^50keV),反演得到环电流离子微分通量随L值/纬度/地方时的三维分布与能谱.所得离子通量呈现显著不对称的部分环电流特征,主要分布在低纬-赤道区磁午夜前后至黎明前数小时,L值约为3.5~6.5的区域;将反演得到的磁午夜后赤道区环电流离子通量能谱,与THEMIS卫星当地测量得到的此区域同时的能谱作比较,两者符合得很好;证明本文发展的差分体像素CT是由多卫星ENA二维图像重建暴时环电流离子分布的有效方法. 展开更多
关键词 ENA成像 差分CT twins卫星 环电流 磁暴
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STRAIN INDUCED STRUCTURAL TRANSITION OF INTERFACES AND TWINS IN A HOT-DEFORMED DUAL-PHASE TIAL ALLOY 被引量:2
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作者 CHEN GuoFiang WANG Jinguo ZHANG Lichun and YE Hengqiang(State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, P. R. China Laboratory of Atomic Imaging of Solids, Institute of Metal Researc 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1995年第Z1期273-286,共14页
The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of st... The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2/γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys. 展开更多
关键词 strain induced structural transition interfacial structure deformation twins intermetallic TiAl alloy HREM
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Effects of deformation twins on microstructure evolution,mechanical properties and corrosion behaviors in magnesium alloys-A review 被引量:5
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作者 Lianhui Li Wenhong Liu +2 位作者 Fugang Qi Di Wu Zhiqiang Zhang 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第9期2334-2353,共20页
Due to lattice reorientation,grain segmentation,induced recrystallization,twins play a very important role in regulating texture,refining grains,improving mechanical properties and corrosion resistance,and has receive... Due to lattice reorientation,grain segmentation,induced recrystallization,twins play a very important role in regulating texture,refining grains,improving mechanical properties and corrosion resistance,and has received more extensive attention.Numerous studies have shown that{10-12}<10-11>tensile twins(TTWs)are easily activated in large quantities due to the lower critical resolve shear stresses(CRSS).Introduction of TTWs under uniaxial compression improved the strength,ductility,and formability of magnesium(Mg)alloys.Moreover,TTWs produced by multi-directional impact forging(MDIF)can optimize the microstructure by dividing grains and promoting recrystallization,resulting in significant improvement of mechanical properties.Although{10-11}<10-12>compressive twins(CTWs)and{10-11}-{10-12}double twins(DTWs)can promote dynamic recrystallization(DRX),they are also favorable nucleation sites for cracks.In addition,the type and volume fraction of twins can affect the corrosion resistance,and they also play different roles in the corrosion process of different Mg alloys.Twins have shown great potential for improving structure and properties,but a comprehensive and critical discussion of twins in Mg alloys is still lacking.Therefore,based on previous studies,this article reviews the common types and variants of twins in Mg alloys,influencing factors,and their effects on the microstructure,mechanical properties and corrosion resistance.In addition,some interesting ideas are being proposed for further research. 展开更多
关键词 twins Mg alloy Microstructure Mechanical properties Corrosion resistance
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Building the metaverse using digital twins at all scales,states,and relations 被引量:1
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作者 Zhihan LV Shuxuan XIE +2 位作者 Yuxi LI M.Shamim HOSSAIN Abdulmotaleb El SADDIK 《Virtual Reality & Intelligent Hardware》 2022年第6期459-470,共12页
Developments in new-generation information technology have enabled Digital Twins to reshape the physical world into a virtual digital space and provide technical support for constructing the Metaverse.Metaverse object... Developments in new-generation information technology have enabled Digital Twins to reshape the physical world into a virtual digital space and provide technical support for constructing the Metaverse.Metaverse objects can be at the micro-,meso-,or macroscale.The Metaverse is a complex collection of solid,liquid,gaseous,plasma,and other uncertain states.Additionally,the Metaverse integrates tangibles with social relations,such as interpersonal(friends,partners,and family)and social relations(ethics,morality,and law).This review introduces some principles and laws,such as broken windows theory,small-world phenomenon,survivor bias,and herd behavior,for constructing a Digital Twins model for social relations.Therefore,from multiple perspectives,this article reviews mappings of tangible and intangible real-world objects to the Metaverse using the Digital Twins model. 展开更多
关键词 Digital twins Metaverse SENSOR
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