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Impact toughness,crack initiation and propagation mechanism of Ti6422 alloy with multi-level lamellar microstructure
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作者 Jie Shen Zhihao Zhang Jianxin Xie 《International Journal of Minerals,Metallurgy and Materials》 2026年第2期595-609,共15页
The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.... The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.By adjusting the furnace cooling time after solution treatment and the aging temperature,Ti6422 alloy samples were developed with a multi-level lamellar microstructure,in-cluding microscaleαcolonies and α_(p) lamellae,as well as nanoscale α_(s) phases.Extending the furnace cooling time after solution treatment at 920℃ for 1 h from 240 to 540 min,followed by aging at 600℃ for 6 h,increased the α_(p) lamella content,reduced the α_(s) phase content,expanded theαcolonies and α_(p) lamellae size,and improved the impact toughness from 22.7 to 53.8 J/cm^(2).Additionally,under the same solution treatment,raising the aging temperature from 500 to 700℃ resulted in a decrease in the α_(s) phase content and a growth in the thickness of the α_(p) lamella and α_(s) phase.The impact toughness increased significantly with these changes.Samples with high α_(p) lamellae content or large α_(s) phase size exhibited high crack initiation and propagation energies.Impact deformation caused severe kinking of the α_(p) lamellae in crack initiation and propagation areas,leading to a uniform and high-density kernel average misorientation(KAM)distribu-tion,enhancing plastic deformation coordination and uniformity.Moreover,the multidirectional arrangement of coarserαcolonies and α_(p) lamellae continuously deflect the crack propagation direction,inhibiting crack propagation. 展开更多
关键词 novel titanium alloy multi-level lamellar microstructure impact toughness crack initiation and propagation
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A Multi-Level Semantic Constraint Approach for Highway Tunnel Scene Twin Modeling 被引量:2
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作者 LI Yufei XIE Yakun +3 位作者 CHEN Mingzhen ZHAO Yaoji TU Jiaxing HU Ya 《Journal of Geodesy and Geoinformation Science》 2025年第2期37-56,共20页
As a key node of modern transportation network,the informationization management of road tunnels is crucial to ensure the operation safety and traffic efficiency.However,the existing tunnel vehicle modeling methods ge... As a key node of modern transportation network,the informationization management of road tunnels is crucial to ensure the operation safety and traffic efficiency.However,the existing tunnel vehicle modeling methods generally have problems such as insufficient 3D scene description capability and low dynamic update efficiency,which are difficult to meet the demand of real-time accurate management.For this reason,this paper proposes a vehicle twin modeling method for road tunnels.This approach starts from the actual management needs,and supports multi-level dynamic modeling from vehicle type,size to color by constructing a vehicle model library that can be flexibly invoked;at the same time,semantic constraint rules with geometric layout,behavioral attributes,and spatial relationships are designed to ensure that the virtual model matches with the real model with a high degree of similarity;ultimately,the prototype system is constructed and the case region is selected for the case study,and the dynamic vehicle status in the tunnel is realized by integrating real-time monitoring data with semantic constraints for precise virtual-real mapping.Finally,the prototype system is constructed and case experiments are conducted in selected case areas,which are combined with real-time monitoring data to realize dynamic updating and three-dimensional visualization of vehicle states in tunnels.The experiments show that the proposed method can run smoothly with an average rendering efficiency of 17.70 ms while guaranteeing the modeling accuracy(composite similarity of 0.867),which significantly improves the real-time and intuitive tunnel management.The research results provide reliable technical support for intelligent operation and emergency response of road tunnels,and offer new ideas for digital twin modeling of complex scenes. 展开更多
关键词 highway tunnel twin modeling multi-level semantic constraints tunnel vehicles multidimensional modeling
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Research on Multi-Level Automatic Filling Optimization Design Method for Layered Cross-Sectional Layout of Umbilical 被引量:1
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作者 YIN Xu FAN Zhi-rui +4 位作者 CAO Dong-hui LIU Yu-jie LI Meng-shu YAN Jun YANG Zhi-xun 《China Ocean Engineering》 2025年第5期891-903,共13页
The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly comple... The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly complex layout combinations.Furthermore,due to constraints in component quantity and geometry within the cross-sectional layout,filler bodies must be incorporated to maintain cross-section performance.Conventional design approaches based on manual experience suffer from inefficiency,high variability,and difficulties in quantification.This paper presents a multi-level automatic filling optimization design method for umbilical cross-sectional layouts to address these limitations.Initially,the research establishes a multi-objective optimization model that considers compactness,balance,and wear resistance of the cross-section,employing an enhanced genetic algorithm to achieve a near-optimal layout.Subsequently,the study implements an image processing-based vacancy detection technique to accurately identify cross-sectional gaps.To manage the variability and diversity of these vacant regions,the research introduces a multi-level filling method that strategically selects and places filler bodies of varying dimensions,overcoming the constraints of uniform-size fillers.Additionally,the method incorporates a hierarchical strategy that subdivides the complex cross-section into multiple layers,enabling layer-by-layer optimization and filling.This approach reduces manufac-turing equipment requirements while ensuring practical production process feasibility.The methodology is validated through a specific umbilical case study.The results demonstrate improvements in compactness,balance,and wear resistance compared with the initial cross-section,offering novel insights and valuable references for filler design in umbilical cross-sections. 展开更多
关键词 UMBILICAL cross-sectional layout multi-level filling layered layout optimization design
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Effect of Withdrawal Rate on Non-uniform Distribution of Eutectic in Ni-based Single Crystal Superalloy Castings
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作者 Zhao Yunxing Yu Jingyi +1 位作者 Ma Dexin Huang Zaiwang 《稀有金属材料与工程》 北大核心 2025年第8期1934-1939,共6页
The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdraw... The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdrawal rate is a critical parameter affecting the spatial distribution ofγ/γ′eutectic along gravity direction.The results show that theγ/γ′eutectic fraction of the upper platform surface is always higher than that of the lower one,regardless of withdrawal rate.As the withdrawal rate decreases,there is a significant increase inγ/γ′eutectic fraction on the upper surface,while it decreases on the lower surface.The upward accumulation ofγ/γ′eutectic becomes more severe as the withdrawal rate decreases.It is also found that the percentage of Al+Ta is positively correlated with theγ/γ′eutectic fraction.Thermo-solute convection of Al and Ta solutes in the solidification front is the prime reason for the non-uniform distribution of eutectic.The non-uniform distribution ofγ/γ′eutectic cannot be eliminated even after subsequent solution heat treatment,resulting in excess eutectic on the upper surface and thus leading to the scrapping of the blade. 展开更多
关键词 Ni-based single crystal superalloy EUTECTICS withdrawal rate thermo-solute convection
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Mindfulness improves negative psychotic symptoms through reducing emotional and social withdrawal
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作者 Carmen Borrás-Sansaloni Marina Ricco-Pérez +3 位作者 Antoni Mayol Capilla Navarro-Guzmán JoséManuel García-Montes Emilio Lopez-Navarro 《World Journal of Psychiatry》 2025年第4期167-177,共11页
BACKGROUND Psychotic disorders are characterized by both positive symptoms(hallucinations,delusions)and negative symptoms(emotional blunting,anhedonia)that impair daily functioning.While antipsychotic drugs and psycho... BACKGROUND Psychotic disorders are characterized by both positive symptoms(hallucinations,delusions)and negative symptoms(emotional blunting,anhedonia)that impair daily functioning.While antipsychotic drugs and psychological interventions are effective when addressing positive symptoms,treatment of negative symptoms remains an ongoing challenge.Mindfulness-based interventions(MBIs)have been shown to reduce negative psychotic symptoms.However,as negative psychotic symptoms are assessed as a sole entity rather than a sum of manifestations,the effect of MBIs remains unclear.AIM To examine the effects of MBI in addition to integrated rehabilitation treatment(IRT)for people experiencing psychosis on each of the negative psychotic symptoms.METHODS A randomized controlled clinical trial with preintervention and postintervention measures was designed.The main outcome variable was negative psychotic symptoms assessed through the seven subscales of the Spanish version of the positive and negative syndrome scale.Data were analyzed using a repeated measures analysis of variance and reliable change index calculation.RESULTS There were no statistical differences between groups at the preintervention assessment.Statistically significant differences were found after MBI for the time in emotional withdrawal(F=37.75,P<0.001,η2=0.437)and social withdrawal(F=37.75,P<0.001,η2=0.437).CONCLUSION MBI added to IRT reduced the lack of interest and involvement with affective commitment to daily life activities,and interest and engagement in social activities increased.These negative psychotic symptoms were not improved by IRT alone. 展开更多
关键词 MINDFULNESS PSYCHOSIS Clinical trial Emotional withdrawal Social functioning SCHIZOPHRENIA
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Personalizing withdrawal time by insertion time to achieve target adenoma detection rate in colonoscopy
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作者 Bing-Xin Xu Cong-Zhou Xu +3 位作者 Hao-Yan Zhang Xu-Jin Chen Bing-Ni Wei Cheng Yang 《World Journal of Gastroenterology》 2025年第38期105-119,共15页
BACKGROUND Adenoma detection rate(ADR),a key colonoscopy quality metric,varies with patient demographics and procedural factors.AIM To identify independent predictors of≥25%ADR,develop a risk model,and propose withdr... BACKGROUND Adenoma detection rate(ADR),a key colonoscopy quality metric,varies with patient demographics and procedural factors.AIM To identify independent predictors of≥25%ADR,develop a risk model,and propose withdrawal durations based on different insertion times.METHODS We retrospectively analyzed 830 cases using logistic regression and identified four key factors,validated in a prospective cohort of 5699 patients.Their importance was confirmed using random forest(RF),extreme gradient boosting(XGBoost)and light gradient boosting machine(LightGBM).Attempts to determine targetachieving withdrawal time by grouping cases based on insertion time and Cox regression were inconclusive.Using the 5699-case dataset,we developed a predictive model combining support vector machine(SVM)with XGBoost.We built a Shiny app using this model for clinical application.RESULTS Multivariate logistic regression identified age[odds ratio(OR)=1.05;95%confidence interval(CI):1.03-1.08;P<0.001],male(OR=1.79;95%CI:1.32-2.41;P=0.005),higher endoscopist experience(OR=1.79;95%CI:1.20-2.68;P=0.005),and longer withdrawal time(P<0.001)as independent risk factors for colorectal adenoma.A nomogram demonstrated strong discrimination[area under the curve(AUC)=0.720],with robust calibration and decision-curve performance.Feature importance via RF,XGBoost,and LightGBM confirmed key predictors.A hybrid model combining SVM regression for withdrawal-time estimation and XGBoost classification achieved stable results,with XGBoost reporting AUCs of 0.640 in training and 0.610 in testing,and similar validation outcomes.Deployed via a Shiny app for clinical use.However,model discrimination was modest(AUC:0.61-0.64),suggesting that clinical utility requires further refinement.CONCLUSION A hybrid SVM-XGBoost model using four key endoscopic factors was independently validated and is available as a Shiny app,delivering real-time decision support to streamline endoscopy and enhance clinical outcomes. 展开更多
关键词 COLONOSCOPY withdrawal time Insertion time Adenoma detection rate Machine learning
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Prudence is never excessive:Caution warranted in 5-aminosalicylic acid derivatives withdrawal for ulcerative colitis
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作者 Antonietta Gerarda Gravina Raffaele Pellegrino Alessandro Federico 《World Journal of Gastroenterology》 2025年第44期173-177,共5页
This invited commentary discusses the recent study by Atay et al,which investigated relapse rates following the spontaneous withdrawal of maintenance 5-aminosalicylates in ulcerative colitis.The discussion focuses,in ... This invited commentary discusses the recent study by Atay et al,which investigated relapse rates following the spontaneous withdrawal of maintenance 5-aminosalicylates in ulcerative colitis.The discussion focuses,in this patient setting,on the possible reasons that might prompt clinicians to pursue such exit strategies,and on the importance of exercising caution in these decisions,given the extremely narrow subsets of patients for whom international guidelines allow any degree of leeway. 展开更多
关键词 Ulcerative colitis Inflammatory bowel disease 5-aminosalicylic acid derivatives withdrawAL Exit strategy
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Outcomes of 5-aminosalicylates withdrawal due to non-adherence in ulcerative colitis patients:A step toward evaluating intermittent therapy
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作者 Ali Atay Mucahit Ergul +4 位作者 Oguz Ozturk Kadir C Acun Yavuz Cagir Muhammed B Durak Ilhami Yuksel 《World Journal of Gastroenterology》 2025年第30期45-55,共11页
BACKGROUND 5-aminosalicylates(5-ASA)are the primary treatment for mild to moderate ulcerative colitis(UC).Maintenance therapy with 5-ASA has been shown to reduce both the risk of relapse and colorectal cancer.AIM To e... BACKGROUND 5-aminosalicylates(5-ASA)are the primary treatment for mild to moderate ulcerative colitis(UC).Maintenance therapy with 5-ASA has been shown to reduce both the risk of relapse and colorectal cancer.AIM To evaluate the outcomes of 5-ASA withdrawal due to non-adherence in UC patients while in remission on monotherapy.METHODS Adult patients with UC who were followed up between July 2019 and April 2025 were screened.Patients in remission receiving 5-ASA monotherapy who experienced treatment withdrawal due to non-adherence were included in this study.RESULTS Among 880 patients with UC,30(3.4%)had 5-ASA withdrawal due to nonadherence while in remission on monotherapy.Twelve patients(40%)had disease relapse after a median of 20 months.The rate of patients in remission was 89%in the first year,decreasing to 73%in the second year,and to 64%in the third year.There were no significant differences between patients with and without relapse in terms of demographics,disease extent,remission duration before 5-ASA withdrawal,previous medications,steroid dependence,5-ASA formulation,baseline inflammatory markers,or partial and endoscopic Mayo scores.Most patients(75%)who experienced relapse were successfully treated with 5-ASA monotherapy,while one-fourth of them required corticosteroids.No patients required biologic agents,hospitalization,or surgical intervention.CONCLUSION Intermittent therapy may be safe and feasible for UC patients,especially those in long-term remission,with treatment interruption up to one year considered acceptable. 展开更多
关键词 Inflammatory bowel disease Ulcerative colitis 5-aminosalicylates Treatment withdrawal RELAPSE Intermittent therapy
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Multi-relation spatiotemporal graph residual network model with multi-level feature attention:A novel approach for landslide displacement prediction
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作者 Ziqian Wang Xiangwei Fang +3 位作者 Wengang Zhang Xuanming Ding Luqi Wang Chao Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第7期4211-4226,共16页
Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,ther... Accurate prediction of landslide displacement is crucial for effective early warning of landslide disasters.While most existing prediction methods focus on time-series forecasting for individual monitoring points,there is limited research on the spatiotemporal characteristics of landslide deformation.This paper proposes a novel Multi-Relation Spatiotemporal Graph Residual Network with Multi-Level Feature Attention(MFA-MRSTGRN)that effectively improves the prediction performance of landslide displacement through spatiotemporal fusion.This model integrates internal seepage factors as data feature enhancements with external triggering factors,allowing for accurate capture of the complex spatiotemporal characteristics of landslide displacement and the construction of a multi-source heterogeneous dataset.The MFA-MRSTGRN model incorporates dynamic graph theory and four key modules:multilevel feature attention,temporal-residual decomposition,spatial multi-relational graph convolution,and spatiotemporal fusion prediction.This comprehensive approach enables the efficient analyses of multi-source heterogeneous datasets,facilitating adaptive exploration of the evolving multi-relational,multi-dimensional spatiotemporal complexities in landslides.When applying this model to predict the displacement of the Liangshuijing landslide,we demonstrate that the MFA-MRSTGRN model surpasses traditional models,such as random forest(RF),long short-term memory(LSTM),and spatial temporal graph convolutional networks(ST-GCN)models in terms of various evaluation metrics including mean absolute error(MAE=1.27 mm),root mean square error(RMSE=1.49 mm),mean absolute percentage error(MAPE=0.026),and R-squared(R^(2)=0.88).Furthermore,feature ablation experiments indicate that incorporating internal seepage factors improves the predictive performance of landslide displacement models.This research provides an advanced and reliable method for landslide displacement prediction. 展开更多
关键词 Landslide displacement prediction Spatiotemporal fusion Dynamic graph Data feature enhancement multi-level feature attention
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A robust method for large-scale route optimization on lunar surface utilizing a multi-level map model
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作者 Yutong JIA Shengnan ZHANG +5 位作者 Bin LIU Kaichang DI Bin XIE Jing NAN Chenxu ZHAO Gang WAN 《Chinese Journal of Aeronautics》 2025年第3期134-150,共17页
As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could ra... As we look ahead to future lunar exploration missions, such as crewed lunar exploration and establishing lunar scientific research stations, the lunar rovers will need to cover vast distances. These distances could range from kilometers to tens of kilometers, and even hundreds and thousands of kilometers. Therefore, it is crucial to develop effective long-range path planning for lunar rovers to meet the demands of lunar patrol exploration. This paper presents a hierarchical map model path planning method that utilizes the existing high-resolution images, digital elevation models and mineral abundance maps. The objective is to address the issue of the construction of lunar rover travel costs in the absence of large-scale, high-resolution digital elevation models. This method models the reference and semantic layers using the middle- and low-resolution remote sensing data. The multi-scale obstacles on the lunar surface are extracted by combining the deep learning algorithm on the high-resolution image, and the obstacle avoidance layer is modeled. A two-stage exploratory path planning decision is employed for long-distance driving path planning on a global–local scale. The proposed method analyzes the long-distance accessibility of various areas of scientific significance, such as Rima Bode. A high-precision digital elevation model is created using stereo images to validate the method. Based on the findings, it can be observed that the entire route spans a distance of 930.32 km. The route demonstrates an impressive ability to avoid meter-level impact craters and linear structures while maintaining an average slope of less than 8°. This paper explores scientific research by traversing at least seven basalt units, uncovering the secrets of lunar volcanic activities, and establishing ‘golden spike’ reference points for lunar stratigraphy. The final result of path planning can serve as a valuable reference for the design, mission demonstration, and subsequent project implementation of the new manned lunar rover. 展开更多
关键词 Crewed lunar exploration Long-range path planningi multi-level map Deep learning Volcanic activities
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Multi-level distribution alignment-based domain adaptation for segmentation of 3D neuronal soma images
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作者 Li Ma Xuantai Xu Xiaoquan Yang 《Journal of Innovative Optical Health Sciences》 2025年第6期69-85,共17页
Deep learning networks are increasingly exploited in the field of neuronal soma segmentation.However,annotating dataset is also an expensive and time-consuming task.Unsupervised domain adaptation is an effective metho... Deep learning networks are increasingly exploited in the field of neuronal soma segmentation.However,annotating dataset is also an expensive and time-consuming task.Unsupervised domain adaptation is an effective method to mitigate the problem,which is able to learn an adaptive segmentation model by transferring knowledge from a rich-labeled source domain.In this paper,we propose a multi-level distribution alignment-based unsupervised domain adaptation network(MDA-Net)for segmentation of 3D neuronal soma images.Distribution alignment is performed in both feature space and output space.In the feature space,features from different scales are adaptively fused to enhance the feature extraction capability for small target somata and con-strained to be domain invariant by adversarial adaptation strategy.In the output space,local discrepancy maps that can reveal the spatial structures of somata are constructed on the predicted segmentation results.Then thedistribution alignment is performed on the local discrepancies maps across domains to obtain a superior discrepancy map in the target domain,achieving refined segmentation performance of neuronal somata.Additionally,after a period of distribution align-ment procedure,a portion of target samples with high confident pseudo-labels are selected as training data,which assist in learning a more adaptive segmentation network.We verified the superiority of the proposed algorithm by comparing several domain adaptation networks on two 3D mouse brain neuronal somata datasets and one macaque brain neuronal soma dataset. 展开更多
关键词 Unsupervised domain adaptation multi-level distribution alignment pseudo-labels 3D neuronal soma images
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MLRT-UNet:An Efficient Multi-Level Relation Transformer Based U-Net for Thyroid Nodule Segmentation
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作者 Kaku Haribabu Prasath R Praveen Joe IR 《Computer Modeling in Engineering & Sciences》 2025年第4期413-448,共36页
Thyroid nodules,a common disorder in the endocrine system,require accurate segmentation in ultrasound images for effective diagnosis and treatment.However,achieving precise segmentation remains a challenge due to vari... Thyroid nodules,a common disorder in the endocrine system,require accurate segmentation in ultrasound images for effective diagnosis and treatment.However,achieving precise segmentation remains a challenge due to various factors,including scattering noise,low contrast,and limited resolution in ultrasound images.Although existing segmentation models have made progress,they still suffer from several limitations,such as high error rates,low generalizability,overfitting,limited feature learning capability,etc.To address these challenges,this paper proposes a Multi-level Relation Transformer-based U-Net(MLRT-UNet)to improve thyroid nodule segmentation.The MLRTUNet leverages a novel Relation Transformer,which processes images at multiple scales,overcoming the limitations of traditional encoding methods.This transformer integrates both local and global features effectively through selfattention and cross-attention units,capturing intricate relationships within the data.The approach also introduces a Co-operative Transformer Fusion(CTF)module to combine multi-scale features from different encoding layers,enhancing the model’s ability to capture complex patterns in the data.Furthermore,the Relation Transformer block enhances long-distance dependencies during the decoding process,improving segmentation accuracy.Experimental results showthat the MLRT-UNet achieves high segmentation accuracy,reaching 98.2% on the Digital Database Thyroid Image(DDT)dataset,97.8% on the Thyroid Nodule 3493(TG3K)dataset,and 98.2% on the Thyroid Nodule3K(TN3K)dataset.These findings demonstrate that the proposed method significantly enhances the accuracy of thyroid nodule segmentation,addressing the limitations of existing models. 展开更多
关键词 Thyroid nodules endocrine system multi-level relation transformer U-Net self-attention external attention co-operative transformer fusion thyroid nodules segmentation
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黄河流域平原地区农村宅基地使用权退出的立法路径选择
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作者 张庆华 《德州学院学报》 2026年第1期69-74,共6页
中国式现代化背景下农村宅基地大量闲置是农村宅基地使用权退出的现实原因。黄河流域平原地区地势平坦,交通和通讯网络发达,对退出的宅基地进行统一集中整治,会产生良好的生态效益、经济效益和社会效益,相对于实践,宅基地使用权退出立... 中国式现代化背景下农村宅基地大量闲置是农村宅基地使用权退出的现实原因。黄河流域平原地区地势平坦,交通和通讯网络发达,对退出的宅基地进行统一集中整治,会产生良好的生态效益、经济效益和社会效益,相对于实践,宅基地使用权退出立法的滞后性主要表现为,宅基地使用权退出人的资格条件过于笼统;通过继承房屋取得的宅基地使用权退出制度不明确;宅基地使用权退出的方式尚待完善;宅基地使用权退出的生态保护立法不足等。因此,宅基地使用权退出人的资格条件,住宅继承人宅基地使用权退出规则,宅基地使用权的退出方式、法律后果以及生态保护应进行立法考量。 展开更多
关键词 黄河流域 宅基地使用权 有偿退出 立法路径
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氟苯尼考在修水黄羽乌鸡体内不同组织的残留消除规律研究
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作者 陈文 周佳翊 +5 位作者 万萍 陶慧慧 陈薇 张大文 廖且根 吴国平 《江西农业大学学报》 北大核心 2026年第1期165-175,共11页
【目的】旨在探究氟苯尼考在修水黄羽乌鸡不同组织中的残留消除规律,明确其在修水黄羽乌鸡体内的休药期,为氟苯尼考在修水黄羽乌鸡养殖中的合理使用提供科学依据,保障修水黄羽乌鸡产品质量安全。【方法】选择42只160日龄健康修水黄羽乌... 【目的】旨在探究氟苯尼考在修水黄羽乌鸡不同组织中的残留消除规律,明确其在修水黄羽乌鸡体内的休药期,为氟苯尼考在修水黄羽乌鸡养殖中的合理使用提供科学依据,保障修水黄羽乌鸡产品质量安全。【方法】选择42只160日龄健康修水黄羽乌鸡,按照20%氟苯尼考粉推荐剂量1.5 g/L饮水连续给药5 d,停药后分别于0.16,1,3,5,9,15,20 d采集肌肉、肝脏、肾脏、皮脂样本。采用液相色谱-串联质谱法对样品中的氟苯尼考和氟苯尼考胺残留量进行测定,并利用休药期软件(WT 1.4)计算出氟苯尼考在修水黄羽乌鸡各个组织中的休药时间。【结果】氟苯尼考在修水黄羽乌鸡体内的休药时间长于普通肉鸡。氟苯尼考在修水黄羽乌鸡肌肉、肝脏、肾脏和皮脂中的休药期分别是11.26,0,0,17.58 d。【结论】为保障修水黄羽乌鸡产品质量安全和消费者健康,建议氟苯尼考在修水黄羽乌鸡体内的休药时间应不少于18 d。 展开更多
关键词 修水黄羽乌鸡 氟苯尼考 氟苯尼考胺 休药期 残留
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Multi-level access control model for tree-like hierarchical organizations
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作者 於光灿 李瑞轩 +3 位作者 卢正鼎 Mudar Sarem 宋伟 苏永红 《Journal of Southeast University(English Edition)》 EI CAS 2008年第3期393-396,共4页
An access control model is proposed based on the famous Bell-LaPadula (BLP) model.In the proposed model,hierarchical relationships among departments are built,a new concept named post is proposed,and assigning secur... An access control model is proposed based on the famous Bell-LaPadula (BLP) model.In the proposed model,hierarchical relationships among departments are built,a new concept named post is proposed,and assigning security tags to subjects and objects is greatly simplified.The interoperation among different departments is implemented through assigning multiple security tags to one post, and the more departments are closed on the organization tree,the more secret objects can be exchanged by the staff of the departments.The access control matrices of the department,post and staff are defined.By using the three access control matrices,a multi granularity and flexible discretionary access control policy is implemented.The outstanding merit of the BLP model is inherited,and the new model can guarantee that all the information flow is under control.Finally,our study shows that compared to the BLP model,the proposed model is more flexible. 展开更多
关键词 multi-level access control hierarchical organization multiple security tags
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养老期望、代际差异与农户宅基地退出意愿——基于CLES数据的实证分析
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作者 张传 郭贯成 纪丰 《农林经济管理学报》 北大核心 2026年第1期129-138,共10页
基于2022年中国土地经济调查(CLES)数据,运用多层回归模型,实证检验养老期望、代际差异对农户宅基地退出意愿的影响及代际差异的调节效应。结果表明:养老期望显著影响农户宅基地退出意愿,其中自我养老期望对农户宅基地退出意愿具有抑制... 基于2022年中国土地经济调查(CLES)数据,运用多层回归模型,实证检验养老期望、代际差异对农户宅基地退出意愿的影响及代际差异的调节效应。结果表明:养老期望显著影响农户宅基地退出意愿,其中自我养老期望对农户宅基地退出意愿具有抑制作用,子女养老期望与社会养老期望具有促进作用,且三者的影响强度依次为子女养老期望最强,自我养老期望次之,社会养老期望最弱;在世代效应与年龄效应的共同作用下,老一代、中生代和新生代农户的宅基地退出意愿呈递增趋势。调节效应分析表明,随着代际更迭,自我养老期望对宅基地退出意愿的抑制作用逐渐弱化,子女养老期望的促进作用也逐步减弱,社会养老期望的影响则未表现出明显变化。据此,建议重视农户养老观念的引导与培育,结合“代际适配”的差异化政策设计,并依托“嵌入式”治理理念,因地制宜推进宅基地退出政策与农村养老服务体系的协同发展,从而为农户自愿有序退出宅基地构建坚实的社会基础。 展开更多
关键词 宅基地退出意愿 养老期望 代际差异 多层回归模型
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U75V重轨钢定向凝固组织模拟及实验研究
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作者 尹杰 丁国 +3 位作者 张建飞 李岩 定巍 曹亚强 《现代交通与冶金材料》 2026年第1期98-106,共9页
通过Procast数值模拟与实验,研究U75V重轨钢定向凝固过程中浇注温度和抽拉速率对凝固组织的影响。结果表明:浇注温度从1490℃升至1535℃时,糊状区宽度减少28.1%;抽拉速率由35µm/s增至100µm/s时,糊状区宽度缩减9.9%。模拟与实... 通过Procast数值模拟与实验,研究U75V重轨钢定向凝固过程中浇注温度和抽拉速率对凝固组织的影响。结果表明:浇注温度从1490℃升至1535℃时,糊状区宽度减少28.1%;抽拉速率由35µm/s增至100µm/s时,糊状区宽度缩减9.9%。模拟与实验分析表明,浇注温度升高和抽拉速率提升使二次枝晶间距减小10%~30%。当浇注温度为1490℃且抽拉速率在50~65µm/s范围内时,柱状晶呈现较优的定向生长趋势。 展开更多
关键词 重轨钢 定向凝固 凝固组织 抽拉速率 浇注温度
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母亲养育压力对学前儿童社会退缩的影响:母亲消极归因与心理控制的链式中介作用
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作者 郭凌韵 陈毅文 《教育生物学杂志》 2026年第1期57-61,71,共6页
目的 分析母亲养育压力如何影响学前儿童的社会退缩,并探讨母亲消极归因与心理控制是否在这一影响过程中发挥中介作用。方法 以学前儿童及其母亲为研究对象,通过母亲报告收集儿童社会偏好量表、养育压力问卷简化版、父母知觉量表儿童责... 目的 分析母亲养育压力如何影响学前儿童的社会退缩,并探讨母亲消极归因与心理控制是否在这一影响过程中发挥中介作用。方法 以学前儿童及其母亲为研究对象,通过母亲报告收集儿童社会偏好量表、养育压力问卷简化版、父母知觉量表儿童责任归因分量表、心理控制量表数据,共获得有效问卷841份。对各研究变量开展描述性统计与相关性检验,并在此基础上构建结构方程模型,同时借助Bootstrap重抽样技术对中介路径进行验证。结果 母亲养育压力、消极归因、心理控制与儿童社会退缩两两间均呈显著正相关(r=0.12~0.51,P<0.001)。母亲养育压力正向预测儿童社会退缩(β=0.20, P<0.001)。Bootstrap检验显示,2条中介路径效应显著(间接效应占总效应的42.25%):母亲养育压力→母亲心理控制→儿童社会退缩(95%CI:0.06~0.15);母亲养育压力→母亲消极归因→母亲心理控制→儿童社会退缩(95%CI:0.02~0.07)。结论 母亲养育压力既直接影响学前儿童社会退缩,还可通过母亲心理控制的单独中介作用,以及消极归因与心理控制的链式中介作用间接影响该行为。 展开更多
关键词 养育压力 儿童社会退缩 消极归因 心理控制
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实体程序协同视角下起诉解除后撤诉的审查与效果——以《民法典合同编通则解释》第54条为核心
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作者 刘子赫 《法治研究》 北大核心 2026年第1期94-107,共14页
《民法典》规定了合同通知解除权的普通形成权性质和通知行使方式,对诉讼外自行通知解除和起诉解除一并适用。《民法典合同编通则解释》第54条专门对起诉解除合同后撤诉又再次起诉的解除时间作出规定,认为撤诉后不发生解除效果,释义书... 《民法典》规定了合同通知解除权的普通形成权性质和通知行使方式,对诉讼外自行通知解除和起诉解除一并适用。《民法典合同编通则解释》第54条专门对起诉解除合同后撤诉又再次起诉的解除时间作出规定,认为撤诉后不发生解除效果,释义书解释增加了解除权行使须经人民法院确认的程序条件,与《民法典》规定形成冲突。从实体法保障相对人信赖目的出发,可将起诉解除后撤诉区分为撤回意思表示型撤诉和撤销意思表示型撤诉,前者应在起诉状副本发出前完成,或在发出后及时向被告撤回解除表示;后者则限于被告尚未形成信赖或未造成损失可撤销的情形。对撤回、撤销意思表示的判断,可以内化于撤诉许可裁量中,保持撤诉与解除通知不生效力的一致性,排除不可撤销与双方和解的情形。实体法需要关注诉讼场景,诉讼行为亦不在实体法评价范围之外。 展开更多
关键词 起诉解除 普通形成权 撤诉 撤回意思表示 撤销意思表示
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北方地区母亲河复苏行动对策与措施研究
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作者 陈春锦 菅宇翔 +1 位作者 王晓红 赵文婧 《中国水利》 2026年第2期29-35,共7页
立足北方地区母亲河存在的水流不畅、生态挤占、资源短缺等问题,研究分析母亲河复苏目标的各项影响因素,基于问题导向和目标导向,提出北方地区母亲河复苏措施制定流程。针对不同类型河湖健康问题,提出退还、通畅、补水、防控四类核心复... 立足北方地区母亲河存在的水流不畅、生态挤占、资源短缺等问题,研究分析母亲河复苏目标的各项影响因素,基于问题导向和目标导向,提出北方地区母亲河复苏措施制定流程。针对不同类型河湖健康问题,提出退还、通畅、补水、防控四类核心复苏措施。通过系统梳理国家与地方现行相关政策及文件,详细阐述了各类措施可依据的指导性制度与技术标准。结合对北方地区母亲河复苏行动“一河(湖)一策”方案的深度剖析及已有河湖治理实践经验,进一步研究细化每类措施的具体技术路径与实施方案,最终形成一套具有区域针对性、可操作性的北方地区母亲河复苏措施技术体系,旨在为相应实践提供清晰的技术指引。文章还以洋河、永定河为典型案例,进行了问题诊断、目标确定及措施匹配分析。 展开更多
关键词 北方地区 母亲河复苏 水资源调度 取用水监管 地下水超采治理 洋河 永定河
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