Multi-scale problems in Computational Fluid Dynamics(CFD)often require numerous simulations across various design parameters.Using a fixed mesh for all cases may fail to capture critical physical features.Moving mesh ...Multi-scale problems in Computational Fluid Dynamics(CFD)often require numerous simulations across various design parameters.Using a fixed mesh for all cases may fail to capture critical physical features.Moving mesh adaptation provides an optimal resource allocation to obtain high-resolution flow-fields on low-resolution meshes.However,most existing methods require manual experience and the flow posteriori information poses great challenges to practical applications.In addition,generating adaptive meshes directly from design parameters is difficult due to highly nonlinear relationships.The diffusion model is currently the most popular model in generative tasks that integrates the diffusion principle into deep learning to capture the complex nonlinear correlations.A dual diffusion framework,Para2Mesh,is proposed to predict the adaptive meshes from design parameters by exploiting the robust data distribution learning ability of the diffusion model.Through iterative denoising,the proposed dual networks accurately reconstruct the flow-field to provide flow features as supervised information,and then achieve rapid and reliable mesh movement.Experiments in CFD scenarios demonstrate that Para2Mesh predicts similar meshes directly from design parameters with much higher efficiency than traditional method.It could become a real-time adaptation tool to assist engineering design and optimization,providing a promising solution for high-resolution flow-field analysis.展开更多
The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological ...The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological molecules needed for life. Titanium oxide (TiO2) can act as a strongly adsorbing surface or a catalytic material. In the present study, a comparative molecular dynamics analysis performed to clarify the adsorbing and diffusion properties of liquid formamide on a TiO2 surface in the presence of water molecules. The structural features of the formamide concentration effect (the accumulation of molecules) on a TiO2 surface in the presence and absence of water solvent are cleared up. Modification of the formamide diffusion abilities mediated by a water solvent is observed to correlate with the formamide-water concentration distribution on the surface.展开更多
Renewable energy production and the balance between production and demand have become increasingly crucial in modern power systems,necessitating accurate forecasting.Traditional deterministic methods fail to capture t...Renewable energy production and the balance between production and demand have become increasingly crucial in modern power systems,necessitating accurate forecasting.Traditional deterministic methods fail to capture the inherent uncertainties associated with intermittent renewable sources and fluctuating demand patterns.This paper proposes a novel denoising diffusion method for multivariate time series probabilistic forecasting that explicitly models the interdependencies between variables through graph modeling.Our framework employs a parallel feature extraction module that simultaneously captures temporal dynamics and spatial correlations,enabling improved forecasting accuracy.Through extensive evaluation on two world real-datasets focused on renewable energy and electricity demand,we demonstrate that our approach achieves state-of-the-art performance in probabilistic energy time series forecasting tasks.By explicitly modeling variable interdependencies and incorporating temporal information,our method provides reliable probabilistic forecasts,crucial for effective decision-making and resource allocation in the energy sector.Extensive experiments validate that our proposed method reduces the Continuous Ranked Probability Score(CRPS)by 2.1%-70.9%,Mean Absolute Error(MAE)by 4.4%-52.2%,and Root Mean Squared Error(RMSE)by 7.9%-53.4%over existing methods on two real-world datasets.展开更多
针对基于知识图谱的推荐系统中存在的高阶建模困难与用户特征建模不足的问题,提出基于多跳机制的扩散图谱推荐模型(a diffusion map recommendation model based on multi-hop mechanism,MultiHop-GDN)。该模型通过端到端方法挖掘知识...针对基于知识图谱的推荐系统中存在的高阶建模困难与用户特征建模不足的问题,提出基于多跳机制的扩散图谱推荐模型(a diffusion map recommendation model based on multi-hop mechanism,MultiHop-GDN)。该模型通过端到端方法挖掘知识图谱高阶语义信息,涵盖知识图谱构建、特征提取网络构建与多跳扩散模型构建三部分内容。利用用户特征和项目特征构建知识图谱;深入分析用户兴趣、偏好和历史行为等信息,构建用户画像和兴趣模型;提出特征提取网络捕获深层次语义信息,通过本文模型的计算得到预测值。在两个公开数据集的对比实验表明,MultiHop-GDN能够同时实现用户和项目的高阶建模,与其他代表论文的模型相比有良好的推荐效果。展开更多
This paper investigates the influence of various knowledge roles on knowledge diffusion empirically.Exponential random graph models(ERGM)are constructed,which provides a novel perspective for examining the factors tha...This paper investigates the influence of various knowledge roles on knowledge diffusion empirically.Exponential random graph models(ERGM)are constructed,which provides a novel perspective for examining the factors that influence knowledge diffusion.Our empirical findings reveal that the endogenous structural effects of the network have a significant impact on the formation of diffusion relationships in citation networks and that there is a correlation between the number of the three knowledge roles-contributors,seekers and brokers-and the likelihood of citation relationship formation in citation networks.展开更多
BACKGROUND Cognitive decline in type 2 diabetes mellitus(T2DM)occurs years before the onset of clinical symptoms.Early detection of this incipient cognitive decline stage,which is T2DM without mild cognitive impairmen...BACKGROUND Cognitive decline in type 2 diabetes mellitus(T2DM)occurs years before the onset of clinical symptoms.Early detection of this incipient cognitive decline stage,which is T2DM without mild cognitive impairment,is critical for clinical intervention,yet it remains elusive and challenging to identify.AIM To identify structural changes in the brains of T2DM patients without cognitive impairment to gain insights into the early-stage cognitive decline.METHODS Using diffusion tensor imaging(DTI),we constructed structural brain networks in 47 T2DM patients and 47 age-/sex-matched healthy controls.Machine learning models incorporating connectivity features were developed to classify T2DM brains and predict disease duration.RESULTS T2DM patients exhibited reduced global/local efficiency and small-worldness,alongside weakened connectivity in cortical regions but enhanced subcortical-frontal connections,suggesting compensatory mechanisms.A classification model leveraging 18 connectivity features achieved 92.5%accuracy in distinguishing T2DM brains.Structural connectivity patterns further predicted disease onset with an error of±1.9 years.CONCLUSION Our findings reveal early-stage brain network reorganization in T2DM,highlighting subcortical-frontal connectivity as a compensatory biomarker.The high-accuracy models demonstrate the potential of DTI-based biomarkers for preclinical cognitive decline detection.展开更多
基金co-supported by the Aeronautical Science Foundation of China(Nos.2018ZA52002 and 2019ZA052011)。
文摘Multi-scale problems in Computational Fluid Dynamics(CFD)often require numerous simulations across various design parameters.Using a fixed mesh for all cases may fail to capture critical physical features.Moving mesh adaptation provides an optimal resource allocation to obtain high-resolution flow-fields on low-resolution meshes.However,most existing methods require manual experience and the flow posteriori information poses great challenges to practical applications.In addition,generating adaptive meshes directly from design parameters is difficult due to highly nonlinear relationships.The diffusion model is currently the most popular model in generative tasks that integrates the diffusion principle into deep learning to capture the complex nonlinear correlations.A dual diffusion framework,Para2Mesh,is proposed to predict the adaptive meshes from design parameters by exploiting the robust data distribution learning ability of the diffusion model.Through iterative denoising,the proposed dual networks accurately reconstruct the flow-field to provide flow features as supervised information,and then achieve rapid and reliable mesh movement.Experiments in CFD scenarios demonstrate that Para2Mesh predicts similar meshes directly from design parameters with much higher efficiency than traditional method.It could become a real-time adaptation tool to assist engineering design and optimization,providing a promising solution for high-resolution flow-field analysis.
文摘The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological molecules needed for life. Titanium oxide (TiO2) can act as a strongly adsorbing surface or a catalytic material. In the present study, a comparative molecular dynamics analysis performed to clarify the adsorbing and diffusion properties of liquid formamide on a TiO2 surface in the presence of water molecules. The structural features of the formamide concentration effect (the accumulation of molecules) on a TiO2 surface in the presence and absence of water solvent are cleared up. Modification of the formamide diffusion abilities mediated by a water solvent is observed to correlate with the formamide-water concentration distribution on the surface.
文摘Renewable energy production and the balance between production and demand have become increasingly crucial in modern power systems,necessitating accurate forecasting.Traditional deterministic methods fail to capture the inherent uncertainties associated with intermittent renewable sources and fluctuating demand patterns.This paper proposes a novel denoising diffusion method for multivariate time series probabilistic forecasting that explicitly models the interdependencies between variables through graph modeling.Our framework employs a parallel feature extraction module that simultaneously captures temporal dynamics and spatial correlations,enabling improved forecasting accuracy.Through extensive evaluation on two world real-datasets focused on renewable energy and electricity demand,we demonstrate that our approach achieves state-of-the-art performance in probabilistic energy time series forecasting tasks.By explicitly modeling variable interdependencies and incorporating temporal information,our method provides reliable probabilistic forecasts,crucial for effective decision-making and resource allocation in the energy sector.Extensive experiments validate that our proposed method reduces the Continuous Ranked Probability Score(CRPS)by 2.1%-70.9%,Mean Absolute Error(MAE)by 4.4%-52.2%,and Root Mean Squared Error(RMSE)by 7.9%-53.4%over existing methods on two real-world datasets.
文摘针对基于知识图谱的推荐系统中存在的高阶建模困难与用户特征建模不足的问题,提出基于多跳机制的扩散图谱推荐模型(a diffusion map recommendation model based on multi-hop mechanism,MultiHop-GDN)。该模型通过端到端方法挖掘知识图谱高阶语义信息,涵盖知识图谱构建、特征提取网络构建与多跳扩散模型构建三部分内容。利用用户特征和项目特征构建知识图谱;深入分析用户兴趣、偏好和历史行为等信息,构建用户画像和兴趣模型;提出特征提取网络捕获深层次语义信息,通过本文模型的计算得到预测值。在两个公开数据集的对比实验表明,MultiHop-GDN能够同时实现用户和项目的高阶建模,与其他代表论文的模型相比有良好的推荐效果。
基金Supported by R&D Program of Beijing Municipal Education Commission(KZ202210005013)Sichuan Social Science Planning Project(SC22B151)。
文摘This paper investigates the influence of various knowledge roles on knowledge diffusion empirically.Exponential random graph models(ERGM)are constructed,which provides a novel perspective for examining the factors that influence knowledge diffusion.Our empirical findings reveal that the endogenous structural effects of the network have a significant impact on the formation of diffusion relationships in citation networks and that there is a correlation between the number of the three knowledge roles-contributors,seekers and brokers-and the likelihood of citation relationship formation in citation networks.
基金Supported by National Natural Science Foundation of China,No.82104698,No.82330058,No.T2341014,and No.32200923.
文摘BACKGROUND Cognitive decline in type 2 diabetes mellitus(T2DM)occurs years before the onset of clinical symptoms.Early detection of this incipient cognitive decline stage,which is T2DM without mild cognitive impairment,is critical for clinical intervention,yet it remains elusive and challenging to identify.AIM To identify structural changes in the brains of T2DM patients without cognitive impairment to gain insights into the early-stage cognitive decline.METHODS Using diffusion tensor imaging(DTI),we constructed structural brain networks in 47 T2DM patients and 47 age-/sex-matched healthy controls.Machine learning models incorporating connectivity features were developed to classify T2DM brains and predict disease duration.RESULTS T2DM patients exhibited reduced global/local efficiency and small-worldness,alongside weakened connectivity in cortical regions but enhanced subcortical-frontal connections,suggesting compensatory mechanisms.A classification model leveraging 18 connectivity features achieved 92.5%accuracy in distinguishing T2DM brains.Structural connectivity patterns further predicted disease onset with an error of±1.9 years.CONCLUSION Our findings reveal early-stage brain network reorganization in T2DM,highlighting subcortical-frontal connectivity as a compensatory biomarker.The high-accuracy models demonstrate the potential of DTI-based biomarkers for preclinical cognitive decline detection.
