检索结果-南通市图书馆

Journal of Advanced Ceramics 2024年第7期13卷 1080-1091页

作者： Yuyu Zhang Xuemeng Zhang Hongkang Ou Bozhe Wang jia sun Qiangang Fu Science and Technology on Thermostructural Composite Materials Laboratory Shaanxi Key Laboratory of Fiber Reinforced Light-Weight CompositesNorthwestern Polytechnical UniversityXi’an 710072China System Design Institute of Hubei Aerospace Technology Academy Wuhan 430040China

To efficiently decrease ablation heat accumulation and improve the ability of ZrC-SiC/TaC coatings to protect carbon/carbon(C/C)composites,a thermally conductive nanonetwork with a ceramic@carbon core-shell structure was designed and ***-derived SiC/TaC with a graphene carbon shell was synthesized and introduced into a ZrC coating by supersonic atmospheric plasma spraying(SAPS).Graphene shell paths increased the heat transfer capability by lowering the surface temperature to approximately 200℃during oxyacetylene *** heat dissipation of the graphene shell in the ZrC-SiC/TaC@C coating reduced the volatilization of low-melting-point phases and delayed the sintering of ZrO_(2) ***,the graphene shell in ZrC-SiC/TaC@C coating decreased the mass and linear ablation rates by 91.4%and 93.7%compared to ZrC-SiC/TaC coating,*** work provided a constructive idea for improving the ablation resistance of the coatings by incorporating carbon nanomaterials as a function of heat dissipation.

关键词： carbon/carbon(C/C)composites carbon nanomaterials core-shell structure polymer-derived ceramic(PDC) ablation resistance

Characteristics of life-cycle carbon dioxide emissions of arterial highway maintenance and the influencing factors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2024年第4期15卷 751-765页

作者： Yao WANG Yuan-Qing WANG Shu-Juan JI Si-jia sun Shu-Hong MA Ya-Nan GAO Key Laboratory of Transport Industry of Management Control and Cycle Repair Technology for Traffic Network Facilities in Ecological Security Barrier Area Chang'an UniversityXi'an 710064China Guangzhou Aids to Navigation Office Southem Navigation Service CenterMaritime Safety AdministrationGuangzhou 51000China

With the focus of highway development transitioning from construction to maintenance,a comprehensive understanding of the characteristics and influencing factors of carbon dioxide(CO_(2))emissions from highway maintenance activities is crucial for formulating effective strategies to promote the low-carbon development of road ***,the quantitative relationships between CO_(2) emissions from highway maintenance schemes and factors such as pavement deterioration,traffic volume,and road grade remain unclear owing to a lack of compre-hensive,multi-category,and real *** real maintenance data from 340 arterial highway segments in China,this study conducts the life cycle assessment(LCA)to estimate CO_(2) emissions from maintenance activities and examines the primary emission sources among various structural layers and ***,multiple linear regression(MLR)analysis is conducted to investigate the impact of traffic volume,road grade,and pavement deterioration on CO_(2) emissions from maintenance projects,and factors influencing the early-stage degradation of pavement *** results demonstrate that average CO_(2) emissions from heavy rehabilitation projects are 6.97 times higher than those from medium rehabilitation *** from heavy rehabilitation projects exhibit a significantly negative linear relationship with the riding quality index(RQI)before maintenance(p<0.05),and emissions from medium rehabilitation projects show a significant negative linear relationship with the pavement condition index(PCI)before maintenance(p<0.05).Emissions from heavy and medium rehabilitation projects are significantly positively correlated with heavy vehicle traffic volume before maintenance(p<0.05).Moreover,the early-stage degradation of PCI after heavy rehabilitation and RQI after medium rehabilitation exhibit significantly negative linear relationships with their respective in-dicators before maintenance(p<0.05).The early-stage d

关键词： Life cycle assessment(LCA) Arterial highway Maintenance Emission factor Pavement performance Traffic volume

Activation of G-protein-coupled receptor 39 reduces neuropathic pain in a rat model

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第3期19卷 687-696页

作者： Longqing Zhang Xi Tan Fanhe Song Danyang Li jiayi Wu Shaojie Gao jia sun Daiqiang Liu Yaqun Zhou Wei Mei Department of Anesthesiology Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Healthand Wuhan Clinical Research Center for Geriatric AnesthesiaTongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei ProvinceChina

Activated G-protein-coupled receptor 39(GPR39)has been shown to attenuate inflammation by interacting with sirtuin 1(SIRT1)and peroxisome proliferator-activated receptor-γcoactivator 1α(PGC-1α).However,whether GPR39 attenuates neuropathic pain remains *** this study,we established a Sprague-Dawley rat model of spared nerve injury-induced neuropathic pain and found that GPR39 expression was significantly decreased in neurons and microglia in the spinal dorsal horn compared with sham-operated *** injection of TC-G 1008,a specific agonist of GPR39,significantly alleviated mechanical allodynia in the rats with spared nerve injury,improved spinal cord mitochondrial biogenesis,and alleviated *** changes were abolished by GPR39 small interfering RNA(siRNA),Ex-527(SIRT1 inhibitor),and PGC-1α*** together,these findings show that GPR39 activation ameliorates mechanical allodynia by activating the SIRT1/PGC-1αpathway in rats with spared nerve injury.

关键词： G-protein-coupled receptor 39(GPR39) neuroinflammation neuropathic pain nuclear respiratory factor 1(NRF1) peroxisome proliferator-activated receptor-γcoactivator 1α(PGC-1α) sirtuin 1(SIRT1) spinal cord mitochondrial transcription factor A(TFAM)

Response of global agricultural productivity anomalies to drought stress in irrigated and rainfed agriculture

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年

作者： Xinxin CHEN Lunche WANG Qian CAO jia sun Zigeng NIU Liu YANG Weixia jiaNG Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina University of Geosciences State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences

The response of agricultural productivity anomalies to drought stress plays a crucial role in the carbon cycle within terrestrial ecosystems and in ensuring food security. However, detailed analysis of how global agricultural productivity anomalies response to drought stress, particularly within irrigated and rainfed agricultural systems, remains insufficient. In this study, the impact of drought stress on agricultural productivity anomalies during the growing season（zcNDVIS）, across both irrigated and rainfed agriculture, were analyzed using a suite of hydro-climatic variables. Specifically, the investigation utilized the multi-scalar Standardized Precipitation Evapotranspiration Index（SPEI）, the Multivariate ENSO Index（MEI）, and the Madden-Julian Oscillation（MJO）. Meanwhile, the relationships between hydroclimatic variables and zcNDVISwere analyzed at one, two, three and four months before the ending of growing season（EOS）. Results showed that（1） the percentages of significant（p<0.1） drying trends varied across the globe from 8.30% to 13.42%, 6.50% to 14.63%, 6.52% to 14.23%, and 6.47%to 14.95% at one-, two-, three-, and four-month lead times before EOS, respectively, during 2001–2020, which represented by the multiscalar SPEI. This observation highlights that most regions across the globe tend to be arid, which could significantly impact agricultural productivity;（2） the global mean correlation coefficients（rmax） for SPEI-1, SPEI-3, SPEI-6, SPEI-12（indicating SPEI at 1-, 3-, 6-, and 12-month lags）, MEI, and MJO with zcNDVISranged between 0.24–0.25, 0.27–0.28, 0.25–0.26, 0.21–0.22, –0.02–0.01 and 0.06–0.11, respectively, across both irrigated and rainfed agriculture system from 2001 to *** productivity anomalies demonstrated a significant correlation with drought stress. The strongest correlations were noted for SPEI-3 and SPEI-6, suggesting a delayed response of crops to drought conditions. This indicates that agriculture ecosystem experiences prolo

关键词：

聚合物转化SiHfCN陶瓷的制备及其吸波性能

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

无机材料学报 2024年第6期39卷 681-690页

作者：张育育吴轶城孙佳付前刚西北工业大学超高温结构复合材料重点实验室陕西省纤维增强轻质复合材料重点实验室西安710072

聚合物转化SiCN陶瓷得益于质量轻和热膨胀系数低等优势,在电磁波吸收领域受到广泛关注。由于电磁损耗机制单一及耐温性不足,SiCN陶瓷的吸波性能有待进一步提高,借助多组元协同作用增强吸波性能是可行的途径之一。本工作对聚氮硅烷结合... 详细信息

聚合物转化SiCN陶瓷得益于质量轻和热膨胀系数低等优势,在电磁波吸收领域受到广泛关注。由于电磁损耗机制单一及耐温性不足,SiCN陶瓷的吸波性能有待进一步提高,借助多组元协同作用增强吸波性能是可行的途径之一。本工作对聚氮硅烷结合不同化合物进行单源化改性得到SiHfCN、SiHfCN-C、SiHfCN-B和SiHfCN-N等四种纳米陶瓷。结果表明:SiHfCN中由于Hf源的含氧量高达13.5%(质量分数),生成HfO_(2)和SiO_(2),使其最低反射损耗(Reflection loss,RL_(min))仅为–13.8 dB,有效吸收带宽(Effective absorption bandwidth,EAB)仅为0.42 GHz。相比于SiHfCN,含Hf聚合物分别与C源、B源和N源共改性增加了聚合物转化陶瓷的界面和导电相,SiHfCN-C、SiHfCN-B和SiHfCN-N的介电常数实部和虚部分别提高了1.4~1.8和2.7~3.9倍,RL_(min)分别为-50.6、-57.3和-63.5 dB,EAB分别为3.53、3.99和4.01 GHz,吸波性能得到了显著改善。SiHfCN-C中大量的自由碳抑制了HfO_(2)的生成,增强了电导损耗。SiHfCN-B中生成了B–N和B–C键,且析出的纳米棒状HfSiO_(4)提供了更多的异质界面,增强了极化损耗。SiHfCN-N中因引入大量N使N–C键数量增加,强化了偶极子极化损耗,同时生成纳米碳片,不仅可以增强电导损耗,而且提供大量界面,改善了阻抗匹配并增强了界面极化,因而SiHfCN-N具有最佳的吸波性能。

关键词：聚合物转化陶瓷聚氮硅烷超高温陶瓷吸波性能

在线全文

学校读者我要写书评

暂无评论

责任伦理视角下的师生关系及其建构

教师教育研究 2024年第2期36卷 59-65页

作者：孙嘉蔚上海师范大学教育学院上海200234

责任是师生关系建立和发展的基石,但在由问责主导的教育监管背景下,师生关系开始面临深层挑战。与服从既定的权力关系或外部规定不同,师生关系作为独特的伦理关系,其形成过程本身应该成为一种出于责任、传递负责任的态度进而唤起学生责... 详细信息

责任是师生关系建立和发展的基石,但在由问责主导的教育监管背景下,师生关系开始面临深层挑战。与服从既定的权力关系或外部规定不同,师生关系作为独特的伦理关系,其形成过程本身应该成为一种出于责任、传递负责任的态度进而唤起学生责任意识的教育实践。师生关系的责任伦理框架涵盖责任的公共性、前瞻性和代际性三个维度。基于责任伦理建构师生关系,应以尊重触发责任意识,以对话促进责任共担,以理解引领责任延续。

关键词：责任伦理师生关系主体他者性

随机干扰下拓扑时变Kuramoto网络事件触发固定时间同步

在线全文

学校读者我要写书评

暂无评论

控制理论与应用 2024年第1期41卷 1-10页

作者：孙佳贾玉斌武永宝董璐刘剑东南大学自动化学院江苏南京210096 东南大学网络空间安全学院江苏南京210096

本文针对一类网络拓扑时变且耦合通道存在随机干扰的Kuramoto型振子网络的同步问题,设计了事件触发机制下的固定时间控制算法.针对耦合网络的拓扑在切换中保持连通的假设,给出了一种具有多层结构的事件触发分布式控制策略,并能够抵消随... 详细信息

本文针对一类网络拓扑时变且耦合通道存在随机干扰的Kuramoto型振子网络的同步问题,设计了事件触发机制下的固定时间控制算法.针对耦合网络的拓扑在切换中保持连通的假设,给出了一种具有多层结构的事件触发分布式控制策略,并能够抵消随机干扰对同步性能带来的负面影响.利用随机Lyapunov稳定理论和固定时间稳定性理论给出了达到实际固定时间相位同步的控制参数条件和同步调节时间的上界.另外,证明了所使用的事件触发机制在引入双曲正切函数之后不会产生Zeno现象,并给出了触发间隔的下界.同时,在推论中给出了本文提出的控制方法也可以应对振子耦合拓扑图不连通情况的结论.最后,通过两组具有不同噪声强度的仿真实验验证了理论分析结果.

关键词： Kuramoto模型网络控制系统随机干扰固定时间同步事件触发控制切换网络

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

塔里木河流域植被动态及潜在因素驱动机制

地球科学 2024年第9期49卷 3399-3410页

作者：岳胜如王伦澈曹茜孙嘉中国地质大学地理与信息工程学院塔里木大学水利与建筑工程学院

塔里木河流域气候极端干旱，探究该区域植被动态特征并定量评价潜在驱动因素的作用强度对维持生态系统功能、实现可持续发展至关重要.基于长时间序列NDVI数据集、气候数据、背景数据及土地利用数据，探究了塔里木河流域2000-2020年植被... 详细信息

塔里木河流域气候极端干旱，探究该区域植被动态特征并定量评价潜在驱动因素的作用强度对维持生态系统功能、实现可持续发展至关重要.基于长时间序列NDVI数据集、气候数据、背景数据及土地利用数据，探究了塔里木河流域2000-2020年植被时空变化趋势和空间自相关性，并利用地理探测器定量评估了潜在驱动因素对NDVI变化的作用强度.结果发现：2000-2020年平均NDVI为0.159,52.63%的区域呈显著增长趋势，增长速率为0.02/10a,NDVI的全局莫兰指数呈波动上升趋势，表现为空间集聚性.土地利用转化、土壤类型、距人造地表距离是塔里木河流域植被变化的主要驱动因素，对NDVI变化的解释力分别为22.20%、8.57%、8.28%.降水是塔里木河流域北部的主导气候因素，气温在西部和南部对NDVI变化的解释力更强，距冰川和积雪的距离是影响NDVI变化不可忽略的因素.任意两因素的交互作用可以提高对NDVI变化的解释力，其中在流域尺度上土地利用转化∩土壤类型(q=29.44%)解释力最强，而在子流域尺度上，解释力最强的交互组合及强度存在差异.本文结果有助于提高对塔里木河流域NDVI变化机制的认识，为干旱半干旱地区生态保护提供科学依据.

关键词：塔里木河流域 NDVI 地理探测器驱动因素植被气候变化

同方期刊数据库

基于可攻击空间假设的陷阱式集成对抗防御网络

在线全文

学校读者我要写书评

暂无评论

软件学报 2024年第4期35卷 1861-1884页

作者：孙家泽温苏雷郑炜陈翔西安邮电大学计算机学院陕西西安710121 陕西省网络数据分析与智能处理重点实验室(西安邮电大学) 陕西西安710121 西安市大数据与智能计算重点实验室(西安邮电大学) 陕西西安710121 西北工业大学软件学院陕西西安710072 南通大学信息科学技术学院江苏南通226019

如今,深度神经网络在各个领域取得了广泛的应用.然而研究表明,深度神经网络容易受到对抗样本的攻击,严重威胁着深度神经网络的应用和发展.现有的对抗防御方法大多需要以牺牲部分原始分类精度为代价,且强依赖于已有生成的对抗样本所提供... 详细信息

如今,深度神经网络在各个领域取得了广泛的应用.然而研究表明,深度神经网络容易受到对抗样本的攻击,严重威胁着深度神经网络的应用和发展.现有的对抗防御方法大多需要以牺牲部分原始分类精度为代价,且强依赖于已有生成的对抗样本所提供的信息,无法兼顾防御的效力与效率.因此基于流形学习,从特征空间的角度提出可攻击空间对抗样本成因假设,并据此提出一种陷阱式集成对抗防御网络Trap-Net. Trap-Net在原始模型的基础上向训练数据添加陷阱类数据,使用陷阱式平滑损失函数建立目标数据类别与陷阱数据类别间的诱导关系以生成陷阱式网络.针对原始分类精度损失问题,利用集成学习的方式集成多个陷阱式网络以在不损失原始分类精度的同时,扩大陷阱类标签于特征空间所定义的靶标可攻击空间.最终, Trap-Net通过探测输入数据是否命中靶标可攻击空间以判断数据是否为对抗样本.基于MNIST、K-MNIST、F-MNIST、CIFAR-10和CIFAR-100数据集的实验表明, Trap-Net可在不损失干净样本分类精确度的同时具有很强的对抗样本防御泛化性,且实验结果验证可攻击空间对抗成因假设.在低扰动的白盒攻击场景中, Trap-Net对对抗样本的探测率高达85%以上.在高扰动的白盒攻击和黑盒攻击场景中, Trap-Net对对抗样本的探测率几乎高达100%.与其他探测式对抗防御方法相比, Trap-Net对白盒和黑盒对抗攻击皆有很强的防御效力.为对抗环境下深度神经网络提供一种高效的鲁棒性优化方法.

关键词：深度神经网络对抗样本集成学习对抗防御鲁棒性优化

在线全文

学校读者我要写书评

暂无评论

直角突变式钢吊车梁疲劳性能及加固方法研究

工程力学 2024年第S1期41卷 275-281页

作者：郑云孙嘉伟赵欣崔涛中冶建筑研究总院有限公司北京100088 建研院检测中心有限公司北京100013 河北工业大学土木与交通学院天津300401 清华大学土木系北京100084

钢吊车梁疲劳破坏问题造成了众多工业建筑的安全事故,也成为工业建筑领域长期的热点问题之一。直角突变式吊车梁是最常见的吊车梁形式,为研究直角突变式吊车梁的疲劳损伤机理和加固方法,改善传统式直角突变支座钢吊车梁的抗疲劳性能,在... 详细信息

钢吊车梁疲劳破坏问题造成了众多工业建筑的安全事故,也成为工业建筑领域长期的热点问题之一。直角突变式吊车梁是最常见的吊车梁形式,为研究直角突变式吊车梁的疲劳损伤机理和加固方法,改善传统式直角突变支座钢吊车梁的抗疲劳性能,在明晰吊车梁支座应力集中位置的基础上,提出三腹板构造的加固措施。采用有限元仿真分析与试验研究相结合的方法,探究了开孔设置方法和三腹板构造对带裂纹支座的加固效果;分析支座处加固前后应力集中部位沿焊缝长度方向的结构应力分布,验证了三腹板构造的工程实际加固效果。结果表明:相比于传统式直角支座,三腹板式支座各位置结构应力最大值下降了约60%,裂纹处应力强度因子下降了约50%;在无裂纹和带裂纹两种工况下,均大可大幅度提升吊车梁疲劳寿命。

关键词：工业建筑吊车梁疲劳性能疲劳寿命疲劳加固