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Influence of negative information dissemination and vaccination behavioral decision-making on epidemic spreading in a three-layer network
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作者 Liang'an Huo Leyao Yin 《Chinese Physics B》 2025年第6期667-681,共15页
Information plays a crucial role in guiding behavioral decisions during public health emergencies. Individuals communicate to acquire relevant knowledge about an epidemic, which influences their decisions to adopt pro... Information plays a crucial role in guiding behavioral decisions during public health emergencies. Individuals communicate to acquire relevant knowledge about an epidemic, which influences their decisions to adopt protective measures.However, whether to disseminate specific information is also a behavioral decision. In light of this understanding, we develop a coupled information–vaccination–epidemic model to depict these co-evolutionary dynamics in a three-layer network. Negative information dissemination and vaccination are treated as separate decision-making processes. We then examine the combined effects of herd and risk motives on information dissemination and vaccination decisions through the lens of game theory. The microscopic Markov chain approach(MMCA) is used to describe the dynamic process and to derive the epidemic threshold. Simulation results indicate that increasing the cost of negative information dissemination and providing timely clarification can effectively control the epidemic. Furthermore, a phenomenon of diminishing marginal utility is observed as the cost of dissemination increases, suggesting that authorities do not need to overinvest in suppressing negative information. Conversely, reducing the cost of vaccination and increasing vaccine efficacy emerge as more effective strategies for outbreak control. In addition, we find that the scale of the epidemic is greater when the herd motive dominates behavioral decision-making. In conclusion, this study provides a new perspective for understanding the complexity of epidemic spreading by starting with the construction of different behavioral decisions. 展开更多
关键词 negative information VACCINATION epidemic spreading behavioral decision-making three-layer network
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Endoscopic resection of colorectal laterally spreading tumors:Clinicopathologic characteristics and risk factors for treatment outcomes
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作者 Li-Hua Guo Ke-Feng Hu +3 位作者 Min Miao Yong Ding Xin-Jun Zhang Guo-Liang Ye 《World Journal of Gastrointestinal Endoscopy》 2025年第6期85-98,共14页
BACKGROUND Colorectal laterally spreading tumors(LSTs)are best treated with endoscopic submucosal dissection or endoscopic mucosal resection.AIM To analyze the clinicopathological and endoscopic profiles of colorectal... BACKGROUND Colorectal laterally spreading tumors(LSTs)are best treated with endoscopic submucosal dissection or endoscopic mucosal resection.AIM To analyze the clinicopathological and endoscopic profiles of colorectal LSTs,determine predictive factors for high-grade dysplasia(HGD)/carcinoma(CA),submucosal invasion,and complications.METHODS We retrospectively assessed the endoscopic and histological characteristics of 375 colorectal LSTs at our hospital between January 2016 and December 2023.We performed univariate and multivariate analysis to identify risk factors associated with HGD/CA,submucosal invasion and complications.RESULTS The numbers of granular(LST-G)and non-granular LST(LST-NG)were 260 and 115,respectively.The rates of low-grade dysplasia and HGD/CA were 60.3%and 39.7%,respectively.Multivariate analysis indicated that a tumor size≥30 mm[odds ratio(OR)=1.934,P=0.032],LST granular nodular mixed type(OR=2.100,P=0.005),and LST non-granular pseudo depressed type(NG-PD)(OR=3.016,P=0.015)were independent risk factors significantly associated with higher odds of HGD/CA.NG-PD(OR=6.506,P=0.001),tumor size(20-29 mm)(OR=2.631,P=0.036)and tumor size≥30 mm(OR=3.449,P=0.016)were associated with increased odds of submucosal invasion.Tumor size≥30 mm(OR=4.888,P=0.003)was a particularly important predictor of complications.A nomogram model demonstrated a satisfactory fit,with an area under the receiver operating characteristic curve of 0.716(95%confidence interval:0.653-0.780),indicating strong predictive performance.CONCLUSION The novel nomogram incorporating tumor size,location,and morphology predicted HGD/CA during endoscopic resection for LSTs.NG-PD lesions larger than 20 mm were more likely to invade the submucosa.Tumor size≥30 mm was an important predictor of complications. 展开更多
关键词 Colorectal neoplasms Laterally spreading tumor Endoscopic morphology Endoscopic submucosal dissection Endoscopic mucosal resection Submucosal invasion
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Explosive information spreading in higher-order networks:Effect of social reinforcement
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作者 Yu Zhou Yingpeng Liu +4 位作者 Liang Yuan Youhao Zhuo Kesheng Xu Jiao Wu Muhua Zheng 《Chinese Physics B》 2025年第3期196-202,共7页
Information spreading has been investigated for many years,but the mechanism of why the information explosively catches on overnight is still under debate.This explosive spreading phenomenon was usually considered dri... Information spreading has been investigated for many years,but the mechanism of why the information explosively catches on overnight is still under debate.This explosive spreading phenomenon was usually considered driven separately by social reinforcement or higher-order interactions.However,due to the limitations of empirical data and theoretical analysis,how the higher-order network structure affects the explosive information spreading under the role of social reinforcement has not been fully explored.In this work,we propose an information-spreading model by considering the social reinforcement in real and synthetic higher-order networks,describable as hypergraphs.Depending on the average group size(hyperedge cardinality)and node membership(hyperdegree),we observe two different spreading behaviors:(i)The spreading progress is not sensitive to social reinforcement,resulting in the information localized in a small part of nodes;(ii)a strong social reinforcement will promote the large-scale spread of information and induce an explosive transition.Moreover,a large average group size and membership would be beneficial to the appearance of the explosive transition.Further,we display that the heterogeneity of the node membership and group size distributions benefit the information spreading.Finally,we extend the group-based approximate master equations to verify the simulation results.Our findings may help us to comprehend the rapidly information-spreading phenomenon in modern society. 展开更多
关键词 explosive information spreading social reinforcement higher-order interactions complex network
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SPREADING SPEED FOR A TIME-SPACE PERIODIC EPIDEMIC MODEL IN DISCRETE MEDIA
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作者 Haiqin ZHAO 《Acta Mathematica Scientia》 2025年第3期1005-1018,共14页
This paper is devoted to investigating the spreading speed of a time-space periodic epidemic model with vital dynamics and standard incidence in discrete media. We establish the existence of the leftward and rightward... This paper is devoted to investigating the spreading speed of a time-space periodic epidemic model with vital dynamics and standard incidence in discrete media. We establish the existence of the leftward and rightward spreading speeds for the infective individuals, which can be used to estimate how fast the disease spreads. To overcome the difficulty arising from the lack of comparison principle for such time-space periodic nonmonotone systems, our proof is mainly based on constructing a series of scalar time-space periodic equations, establishing the spreading speeds for such auxiliary equations and using comparison methods. It may be the first work to study the spreading speed for time-space periodic non-monotone systems. 展开更多
关键词 spreading speed epidemic models time-space periodic habitats
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Smart prediction of liquefaction-induced lateral spreading 被引量:1
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作者 Muhammad Nouman Amjad Raja Tarek Abdoun Waleed El-Sekelly 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2310-2325,共16页
The prediction of liquefaction-induced lateral spreading/displacement(Dh)is a challenging task for civil/geotechnical engineers.In this study,a new approach is proposed to predict Dh using gene expression programming(... The prediction of liquefaction-induced lateral spreading/displacement(Dh)is a challenging task for civil/geotechnical engineers.In this study,a new approach is proposed to predict Dh using gene expression programming(GEP).Based on statistical reasoning,individual models were developed for two topographies:free-face and gently sloping ground.Along with a comparison with conventional approaches for predicting the Dh,four additional regression-based soft computing models,i.e.Gaussian process regression(GPR),relevance vector machine(RVM),sequential minimal optimization regression(SMOR),and M5-tree,were developed and compared with the GEP model.The results indicate that the GEP models predict Dh with less bias,as evidenced by the root mean square error(RMSE)and mean absolute error(MAE)for training(i.e.1.092 and 0.815;and 0.643 and 0.526)and for testing(i.e.0.89 and 0.705;and 0.773 and 0.573)in free-face and gently sloping ground topographies,respectively.The overall performance for the free-face topology was ranked as follows:GEP>RVM>M5-tree>GPR>SMOR,with a total score of 40,32,24,15,and 10,respectively.For the gently sloping condition,the performance was ranked as follows:GEP>RVM>GPR>M5-tree>SMOR with a total score of 40,32,21,19,and 8,respectively.Finally,the results of the sensitivity analysis showed that for both free-face and gently sloping ground,the liquefiable layer thickness(T_(15))was the major parameter with percentage deterioration(%D)value of 99.15 and 90.72,respectively. 展开更多
关键词 Lateral spreading Intelligent modeling Gene expression programming(GEP) Closed-form solution Feature importance
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Influence of network structure on spreading dynamics via tie range
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作者 李敏 宋玉蓉 +3 位作者 宋波 李汝琦 蒋国平 张晖 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期606-613,共8页
There are various phenomena of malicious information spreading in the real society, which cause many negative impacts on the society. In order to better control the spreading, it is crucial to reveal the influence of ... There are various phenomena of malicious information spreading in the real society, which cause many negative impacts on the society. In order to better control the spreading, it is crucial to reveal the influence of network structure on network spreading. Motifs, as fundamental structures within a network, play a significant role in spreading. Therefore, it is of interest to investigate the influence of the structural characteristics of basic network motifs on spreading dynamics.Considering the edges of the basic network motifs in an undirected network correspond to different tie ranges, two edge removal strategies are proposed, short ties priority removal strategy and long ties priority removal strategy. The tie range represents the second shortest path length between two connected nodes. The study focuses on analyzing how the proposed strategies impact network spreading and network structure, as well as examining the influence of network structure on network spreading. Our findings indicate that the long ties priority removal strategy is most effective in controlling network spreading, especially in terms of spread range and spread velocity. In terms of network structure, the clustering coefficient and the diameter of network also have an effect on the network spreading, and the triangular structure as an important motif structure effectively inhibits the spreading. 展开更多
关键词 network spreading network motifs tie range edge removal strategy
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Simulation of crowd evacuation under attack considering emotion spreading
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作者 Yang Wang Ning Ding +1 位作者 Dapeng Dong Yu Zhu 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第12期514-525,共12页
In recent years,attacks against crowded places such as campuses and theaters have had a frequent and negative impact on the security and stability of society.In such an event,the crowd will be subjected to high psycho... In recent years,attacks against crowded places such as campuses and theaters have had a frequent and negative impact on the security and stability of society.In such an event,the crowd will be subjected to high psychological stress and their emotions will rapidly spread to others.This paper establishes the attack-escape evacuation simulation model(AEES-SFM),based on the social force model,to consider emotion spreading under attack.In this model,(1)the attack-escape driving force is considered for the interaction between an attacker and evacuees and(2)emotion spreading among the evacuees is considered to modify the value of the psychological force.To validate the simulation,several experiments were carried out at a university in China.Comparing the simulation and experimental results,it is found that the simulation results are similar to the experimental results when considering emotion spreading.Therefore,the AEES-SFM is proved to be effective.By comparing the results of the evacuation simulation without emotion spreading,the emotion spreading model reduces the evacuation time and the number of casualties by about 30%,which is closer to the real experimental results.The results are still applicable in the case of a 40-person evacuation.This paper provides theoretical support and practical guidance for campus response to violent attacks. 展开更多
关键词 violent attacks crowd evacuation social force model emotion spreading
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Individual dynamics and local heterogeneity provide a microscopic view of the epidemic spreading
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作者 朱友源 沈瑞哲 +1 位作者 董昊 王炜 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期656-663,共8页
The COVID-19 pandemic has caused severe global disasters,highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention measures.While the wid... The COVID-19 pandemic has caused severe global disasters,highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention measures.While the widely used deterministic compartmental models have qualitatively presented continuous “analytical” insight and captured some transmission features,their treatment usually lacks spatiotemporal variation.Here,we propose a stochastic individual dynamical(SID)model to mimic the random and heterogeneous nature of epidemic propagation.The SID model provides a unifying framework for representing the spatiotemporal variations of epidemic development by tracking the movements of each individual.Using this model,we reproduce the infection curves for COVID-19 cases in different areas globally and find the local dynamics and heterogeneity at the individual level that affect the disease outbreak.The macroscopic trend of virus spreading is clearly illustrated from the microscopic perspective,enabling a quantitative assessment of different interventions.Seemingly,this model is also applicable to studying stochastic processes at the “meter scale”,e.g.,human society’s collective dynamics. 展开更多
关键词 Brownian motion epidemic spreading HETEROGENEITY
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Possible Cortical Spreading Depression Recorded Intraoperatively Following a Generalized Seizure: Illustrative Case
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作者 Greg Schaublin Romina Shirka +4 位作者 Nabil Azar Callan Broderick Jayson Neil George R. Lee Kiara Ebinger 《Neuroscience & Medicine》 2024年第3期119-128,共10页
Background: We present a compelling case fitting the phenomenon of cortical spreading depression detected by intraoperative neurophysiological monitoring (IONM) following an intraoperative seizure during a craniotomy ... Background: We present a compelling case fitting the phenomenon of cortical spreading depression detected by intraoperative neurophysiological monitoring (IONM) following an intraoperative seizure during a craniotomy for revascularization. Cortical spreading depression (CSD, also called cortical spreading depolarization) is a pathophysiological phenomenon whereby a wave of depolarization is thought to propagate across the cerebral cortex, creating a brief period of relative neuronal inactivity. The relationship between CSD and seizures is unclear, although some literature has made a correlation between seizures and a cortical environment conducive to CSD. Methods: Intraoperative somatosensory evoked potentials (SSEPs) and electroencephalography (EEG) were monitored continuously during the craniotomy procedure utilizing standard montages. Electrophysiological data from pre-ictal, ictal, and post-ictal periods were recorded. Results: During the procedure, intraoperative EEG captured a generalized seizure followed by a stepwise decrease in somatosensory evoked potential cortical amplitudes, compelling for the phenomenon of CSD. The subsequent partial recovery of neuronal function was also captured electrophysiologically. Discussion: While CSD is considered controversial in some aspects, intraoperative neurophysiological monitoring allowed for the unique analysis of a case demonstrating a CSD-like phenomenon. To our knowledge, this is the first published example of this phenomenon in which intraoperative neurophysiological monitoring captured a seizure, along with a stepwise subsequent reduction in SSEP cortical amplitudes not explained by other variables. 展开更多
关键词 Cortical spreading Depression ELECTROENCEPHALOGRAPHY Intraoperative Neurophysiological Monitoring SEIZURE
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甘肃积石山Ms 6.2地震触发青海中川乡液化型滑坡-泥流特征与成因机理 被引量:16
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作者 许强 彭大雷 +3 位作者 范宣梅 董秀军 张晓超 王欣 《武汉大学学报(信息科学版)》 北大核心 2025年第2期207-222,共16页
2023-12-18甘肃积石山Ms 6.2地震在青海省海东市民和县中川乡金田村和草滩村触发了一起典型地震液化型滑坡-泥流,致使大量房屋被厚达数米的淤泥包围掩埋,因其表现出显著的突发性和超强的流动性,曾被误认为“砂涌”。通过现场调查和遥感... 2023-12-18甘肃积石山Ms 6.2地震在青海省海东市民和县中川乡金田村和草滩村触发了一起典型地震液化型滑坡-泥流,致使大量房屋被厚达数米的淤泥包围掩埋,因其表现出显著的突发性和超强的流动性,曾被误认为“砂涌”。通过现场调查和遥感解译分析,确认该地质灾害为地震触发的液化型滑坡-泥流,并探讨了其成因机理。结果表明:(1)此次地质灾害是地震过程中的振动荷载导致台塬底部饱水粉砂层(黄土层)液化,形成滑坡并转化为泥流,泥流沿沟谷流动到达村庄后漫流成灾,并不是传统意义上的就地“砂涌”;(2)滑源区在液化过程中具体表现为溃散性破坏和侧向扩离两种失稳模式;(3)地震触发土体液化多发生在具有明显应变软化特征的饱水颗粒材料(粉质黄土、细砂等)中。此类地质灾害发生具有突发性,失稳后往往呈流体状远程运动,易造成灾难性后果,应引起高度重视。 展开更多
关键词 地震滑坡-泥流 溃散性滑坡 侧向扩离 地震液化 积石山地震
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基于全球星机会信号的多普勒定位技术 被引量:3
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作者 秦红磊 张宇 +1 位作者 师广婷 王丹瑶 《北京航空航天大学学报》 北大核心 2025年第2期360-367,共8页
以数量庞大的低轨非导航卫星播发的信号作为导航源可不依赖全球导航卫星系统(GNSS)提供定位、导航、授时(PNT)服务能力。对于全球星低轨通信星座播发的机会信号,针对其信噪比低且使用多种扩频码进行复合正交扩频调制的特点导致难以提取... 以数量庞大的低轨非导航卫星播发的信号作为导航源可不依赖全球导航卫星系统(GNSS)提供定位、导航、授时(PNT)服务能力。对于全球星低轨通信星座播发的机会信号,针对其信噪比低且使用多种扩频码进行复合正交扩频调制的特点导致难以提取多普勒的问题,开展基于全球星机会信号的多普勒定位技术研究。通过实测数据对全球星导频信号进行分析,针对性地提出利用平方交谐项实现全球星的导频扩频信号的解码方法,并利用解码结果通过并行码相位搜索捕获算法提取多普勒观测量,建立粗时多普勒定位数学模型并实现定位。实测验证结果表明:利用2颗全球星的实际信号能够达到精度优于100 m的水平定位性能。 展开更多
关键词 定位 机会信号 低轨卫星 全球星 多普勒 扩频通信
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智慧城市建设市民安全感的动态仿真研究 被引量:1
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作者 李德智 黄河 +1 位作者 张勉 周圣华 《系统科学学报》 北大核心 2025年第1期99-105,共7页
近年来,我国智慧城市建设快速推进,公共安全是其重要议题与投资领域。然而,对于智慧城市建设是否会提升市民安全感,现有相关研究基本上停留在静态评价层面,缺乏动态仿真研究。在建立智慧城市建设市民安全感系统评价方法的基础上,设定智... 近年来,我国智慧城市建设快速推进,公共安全是其重要议题与投资领域。然而,对于智慧城市建设是否会提升市民安全感,现有相关研究基本上停留在静态评价层面,缺乏动态仿真研究。在建立智慧城市建设市民安全感系统评价方法的基础上,设定智慧城市建设市民安全感系统变化规则,构建基于多智能体仿真的智慧城市建设市民安全感系统仿真模型。以南京为案例进行研究,发现南京智慧城市建设市民安全感处于中等水平,而且主观规范等内外在影响因素、低安全感信息传播、安全事件发生显著影响市民安全感,并提出智慧城市建设市民安全感提升对策。 展开更多
关键词 智慧城市 市民安全感 多智能体仿真 安全信息传播
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中华文明智能传播的理论建构和实践路径 被引量:1
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作者 陈默 张浩坤 《云南师范大学学报(哲学社会科学版)》 北大核心 2025年第2期21-31,共11页
文章探讨了中华文明国际传播的时代背景,阐释了文明连续性、创新性、包容性与和平性对传播理论和路径的决定作用,剖析了年轻受众数量可观、文明符号略有局限、语言传播颓势稍显及数智内容兴起等现状。同时结合智能传播理论,论证了人工... 文章探讨了中华文明国际传播的时代背景,阐释了文明连续性、创新性、包容性与和平性对传播理论和路径的决定作用,剖析了年轻受众数量可观、文明符号略有局限、语言传播颓势稍显及数智内容兴起等现状。同时结合智能传播理论,论证了人工智能在内容生产、分发及效果评估中的应用。基于此提出“加强顶层设计,构建全局架构”“更新思维逻辑,人机互补并进”“聚焦年轻群体,活化文明符号”“打通信息孤岛,铸造反馈网络”等途径,旨在推动中华文明在国际传播中焕发新活力,为构建人类命运共同体提供坚实的文明力量。 展开更多
关键词 中华文明 国际传播 智能传播理论 传播路径 文化传播
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气候风险、环境行动与地方政府债券发行定价 被引量:1
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作者 顾乃康 邱奇唯 《中国软科学》 北大核心 2025年第1期157-174,共18页
气候风险是否引起投资者关注并在金融市场的资产定价中得以合理反映是气候金融学关注的重要问题之一。以气候风险中最具破坏性、影响范围最广的干旱风险为例,通过考察干旱风险对地方债发行定价的影响,进而对此问题展开探讨。研究发现,... 气候风险是否引起投资者关注并在金融市场的资产定价中得以合理反映是气候金融学关注的重要问题之一。以气候风险中最具破坏性、影响范围最广的干旱风险为例,通过考察干旱风险对地方债发行定价的影响,进而对此问题展开探讨。研究发现,干旱风险显著提高了地方债发行时的信用利差和到期收益率,这种影响在农业产量较高、经济发展水平较低的省市自治区所发行的地方债中更为明显,而干旱风险对地方财政的冲击以及投资者对气候变化的关注度是干旱风险被定价的重要机制。进一步的研究表明,诸如地方水利建设、南水北调工程建设等基于水资源改善的环境行动在总体上能够减轻投资者对未来气候风险的负面预期,进而降低地方债发行时的干旱风险溢价。总之,气候风险已成为影响我国地方债发行定价的重要因素之一,且基于水资源改善的环境行动在抑制气候风险所引起的融资成本提升中发挥着积极作用。 展开更多
关键词 气候风险 干旱风险 地方政府债券 信用利差 环境行动
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文化大国、文化贸易与中华文化传播 被引量:3
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作者 罗立彬 刘博文 《烟台大学学报(哲学社会科学版)》 2025年第1期78-88,100,共12页
在全球化背景下,文化大国可以依托巨大的国内市场规模和独特的文化偏好,提升其文化在全球范围内的经济价值,进而影响全球化文化产品中的文化元素投入偏向。本土文化产业的发展也可以发挥“本地市场效应”,通过文化贸易出口来促进其文化... 在全球化背景下,文化大国可以依托巨大的国内市场规模和独特的文化偏好,提升其文化在全球范围内的经济价值,进而影响全球化文化产品中的文化元素投入偏向。本土文化产业的发展也可以发挥“本地市场效应”,通过文化贸易出口来促进其文化国际传播。中国作为一个文化大国,一方面通过渐进式开放和文化贸易进口,吸引全球文化产品加入中华文化元素并进行全球销售;另一方面通过发挥“本地市场效应”,中国的文化贸易出口也正在以中国文化产品为载体,将中华文化传播至世界各地。今后需要高度重视文化贸易的文化传播功能,在开放中更好平衡文化传播、产业发展和产业国际竞争力的关系,重视文化贸易理论与实践的相互促进作用,充分理解文化产品和服务的经济属性,在文化贸易促进文化传播的实践中,实现经济效益与社会效益相统一。 展开更多
关键词 文化大国 文化产业 文化贸易 中华文化传播
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喷雾助剂对乙基多杀菌素药液在杧果叶片润湿铺展行为的影响
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作者 潘波 王冰洁 +2 位作者 杜长远 林勇 姜蕾 《热带作物学报》 北大核心 2025年第1期180-188,共9页
乙基多杀菌素是防治杧果蓟马的常用药剂之一,农药喷雾助剂的添加可以提高农药的药效。合理选择和使用助剂产品,对提高农药利用率、减少农药使用量至关重要。本研究通过测定添加5种不同类型、不同浓度的农药助剂产品后乙基多杀菌素药液... 乙基多杀菌素是防治杧果蓟马的常用药剂之一,农药喷雾助剂的添加可以提高农药的药效。合理选择和使用助剂产品,对提高农药利用率、减少农药使用量至关重要。本研究通过测定添加5种不同类型、不同浓度的农药助剂产品后乙基多杀菌素药液的静态、动态表面张力,以及药液在杧果叶片正面、背面的接触角、铺展面积和蒸发时间,探究不同类型农药助剂产品在杧果叶片表面的润湿铺展行为。结果表明:添加不同助剂产品均能有效降低乙基多杀菌素药液的静态、动态表面张力,同时降低药液在叶片表面的接触角,提高药液在杧果叶片表面的铺展面积。除高分子类助剂(诺普信天盾)在叶片背面表现出抗蒸发性外,其他助剂产品均缩短了蒸发时间。不同类型的助剂产品在杧果叶片上的润湿性表现并不一致,有机硅类助剂(极润)润湿性最好,其余依次为硅酸金属复合盐类助剂(迈道)、改性植物油(迈飞)、橙皮精油(丹罗丰)、高分子类助剂(诺普信天盾)。通过比较不同处理组药液在杧果叶片正面、背面的润湿铺展行为,得出叶片背面比正面更难以被农药药液润湿。药液的理化性质和叶片的表面结构是影响喷雾液滴在叶片上润湿行为的重要因素。杧果蓟马常常在叶片背面活动取食,因此在防治杧果蓟马时,应根据助剂的类型、蓟马的为害特点选择合适的浓度,才能取得较好的防治效果。研究结果揭示了不同类型助剂在杧果叶片上的润湿铺展行为,为合理选择使用农药喷雾助剂产品提供数据支撑。 展开更多
关键词 喷雾助剂 表面张力 接触角 润湿面积 干燥时间 杧果
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基于在轨点目标估计的图像复原方法
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作者 陈轩 丁与非 +3 位作者 岳鑫 王潜 齐文雯 岳春宇 《激光与红外》 北大核心 2025年第8期1314-1322,共9页
卫星长期在空间环境中开展工作,易受到外力或温度变化的影响,使得图像中出现模糊和拖尾等现象,导致图像质量的退化。如何能够从退化图像提取出目标的有效信息是当前面临的十分棘手的问题。在轨运行阶段卫星不具备对光学系统进行自我修... 卫星长期在空间环境中开展工作,易受到外力或温度变化的影响,使得图像中出现模糊和拖尾等现象,导致图像质量的退化。如何能够从退化图像提取出目标的有效信息是当前面临的十分棘手的问题。在轨运行阶段卫星不具备对光学系统进行自我修复的能力,只能采取图像复原的方式恢复图像原有的应用水平。为了解决相机受到典型光学像差影响导致图像质量退化难题,本文提出了一种基于地面点目标估计点扩散函数的维纳滤波图像复原方法,首先利用地面点目标完成点扩散函数估计,其次对退化图像进行振铃抑制处理,最后完成图像退化处理。方法可以显著改善图像的清晰度,减少图像中“振铃”的出现。以全色和多光谱的退化图像作为仿真分析对象,利用主观目视和客观测试等两种评价方式对不同工况下图像复原质量进行评价,确定退化图像的最佳复原方案。通过对相机的MTF、SNR等核心指标进行复测,并将测试结果与复原前的测试结果进行比较,复原后图像的MTF测试结果提升1.5倍以上,SNR测试结果下降小于5dB,有效保障了相机的成像能力和应用水平。 展开更多
关键词 图像复原 维纳滤波 振铃效应 点扩散函数
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飞秒激光诱导梯度润湿性聚甲基丙烯酸甲酯表面
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作者 杨奇彪 季一平 +3 位作者 蒋元林 黄颖 汪于涛 刘顿 《应用激光》 北大核心 2025年第2期90-97,共8页
研究飞秒激光制备聚甲基丙烯酸甲酯(PMMA)梯度润湿性表面对微流控通道内液滴的操控具有重要意义。采用飞秒激光在PMMA表面加工平行微凹槽结构,通过改变激光能量密度参数来获得不同梯度的润湿性表面。运用接触角测量仪、激光共聚焦显微... 研究飞秒激光制备聚甲基丙烯酸甲酯(PMMA)梯度润湿性表面对微流控通道内液滴的操控具有重要意义。采用飞秒激光在PMMA表面加工平行微凹槽结构,通过改变激光能量密度参数来获得不同梯度的润湿性表面。运用接触角测量仪、激光共聚焦显微镜、能谱仪和扫描电镜分别测量PMMA表面的接触角、粗糙度、化学元素分析以及表面微观形貌,采用高速摄像机观察液滴在梯度润湿性表面的铺展趋势。结果表明:随着激光能量密度的增大,表面接触角呈先增大后减小的趋势,表面粗糙度参数根均方高度和算数平均高度均呈上升趋势,表面C元素含量减少且O元素含量增加。梯度润湿性表面的梯度差越大,液滴铺展速度越快。研究可为PMMA微流控通道的制备提供理论参考。 展开更多
关键词 聚甲基丙烯酸甲酯 梯度润湿性 液滴铺展 飞秒激光
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有机肥撒施机抛撒装置的仿真与试验
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作者 吴昊 胡永冉 +2 位作者 刘希锋 徐冬 李博 《农机化研究》 北大核心 2025年第11期206-212,共7页
针对有机肥撒施机撒施时均匀性不可控、施肥量不稳定等问题,探索有机肥撒施机抛撒装置的关键结构参数对施肥均匀性的影响,并提出了优化设计方案。基于有机肥颗粒的物理特性,应用EDEM离散元软件对有机肥施肥过程进行虚拟仿真试验,建立了... 针对有机肥撒施机撒施时均匀性不可控、施肥量不稳定等问题,探索有机肥撒施机抛撒装置的关键结构参数对施肥均匀性的影响,并提出了优化设计方案。基于有机肥颗粒的物理特性,应用EDEM离散元软件对有机肥施肥过程进行虚拟仿真试验,建立了抛撒部件与有机肥之间的模型关系,以抛撒辊叶片角度、螺旋线数量、叶片螺距和转速为试验因素,以施肥变异系数为试验指标,进行四因素三水平正交试验;使用Design-Expert软件对回归模型求解并开展多目标参数优化,研究得到了抛撒辊最佳参数组合:叶片角度30°、螺旋线数量2条、叶片螺距402 mm、转速349 r/min。为验证抛撒装置抛撒均匀性和协调性,进行了有机肥撒施机场地抛撒验证试验,试验结果优于国家标准,验证了仿真结果的可靠性,有机肥撒施机抛撒装置的肥料抛撒均匀性良好。研究结果对推动有机肥机械化精准施用、促进绿色农业装备技术升级具有重要意义。 展开更多
关键词 有机肥撒施机 抛撒装置 离散元 响应面法
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敦煌莫高窟艺术宝库中的读书图探析 被引量:1
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作者 王波 《图书馆论坛》 北大核心 2025年第4期24-48,148,共26页
文章全面检索、浏览敦煌莫高窟遗存的壁画、彩塑和纸帛画等艺术作品,筛选出读书图。这些图像生动地描绘与读书有关的听法、诵经、传法、度亡等佛教活动,艺术地呈现了中古时期人们的读书学习生活。这些读书图中呈现的读物,多是写在纸帛... 文章全面检索、浏览敦煌莫高窟遗存的壁画、彩塑和纸帛画等艺术作品,筛选出读书图。这些图像生动地描绘与读书有关的听法、诵经、传法、度亡等佛教活动,艺术地呈现了中古时期人们的读书学习生活。这些读书图中呈现的读物,多是写在纸帛等软载体上的经卷,基本取代了汉代画像石中的简牍,反映了书籍的形制演变、代际更替。敦煌莫高窟艺术作品中缤纷多样的读书图虽然具有浓郁的佛教色彩,但折射了中古时期读书和教育活动的普及,见证了当时西北地区崇学尚书的风气,是了解这个时期图书史、阅读史和文化史的重要途径。 展开更多
关键词 敦煌 莫高窟 绘画 读书图 佛教传播 中古教育 图书史 阅读史 文化史
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