期刊文献+
共找到3,435篇文章
< 1 2 172 >
每页显示 20 50 100
Bipolar-growth multi-wing attractors and diverse coexisting attractors in a new memristive chaotic system
1
作者 黄旺鹏 赖强 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第10期310-316,共7页
This article proposes a non-ideal flux-controlled memristor with a bisymmetric sawtooth piecewise function, and a new multi-wing memristive chaotic system(MMCS) based on the memristor is generated. Compared with other... This article proposes a non-ideal flux-controlled memristor with a bisymmetric sawtooth piecewise function, and a new multi-wing memristive chaotic system(MMCS) based on the memristor is generated. Compared with other existing MMCSs, the most eye-catching point of the proposed MMCS is that the amplitude of the wing will enlarge towards the poles as the number of wings increases. Diverse coexisting attractors are numerically found in the MMCS, including chaos,quasi-period, and stable point. The circuits of the proposed memristor and MMCS are designed and the obtained results demonstrate their validity and reliability. 展开更多
关键词 CHAOS memristive chaotic system multi-wing attractors coexisting attractors
下载PDF
Synchronization coexistence in a Rulkov neural network based on locally active discrete memristor
2
作者 马铭磷 谢小华 +2 位作者 杨阳 李志军 孙义闯 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第5期705-709,共5页
At present, many neuron models have been proposed, which can be divided into discrete neuron models and continuous neuron models. Discrete neuron models have the advantage of faster simulation speed and the ease of un... At present, many neuron models have been proposed, which can be divided into discrete neuron models and continuous neuron models. Discrete neuron models have the advantage of faster simulation speed and the ease of understanding complex dynamic phenomena. Due to the properties of memorability, nonvolatility, and local activity, locally active discrete memristors(LADMs) are also suitable for simulating synapses. In this paper, we use an LADM to mimic synapses and establish a Rulkov neural network model. It is found that the change of coupling strength and the initial state of the LADM leads to multiple firing patterns of the neural network. In addition, considering the influence of neural network parameters and the initial state of the LADM, numerical analysis methods such as phase diagram and timing diagram are used to study the phase synchronization. As the system parameters and the initial states of the LADM change, the LADM coupled Rulkov neural network exhibits synchronization transition and synchronization coexistence. 展开更多
关键词 locally active discrete memristor(LADM) Rulkov synchronization coexistence
下载PDF
Corrigendum to “The transition from conservative to dissipative flows in class-B laser model with fold-Hopf bifurcation andcoexisting attractors”
3
作者 李月 陈增强 +1 位作者 袁明峰 仓诗建 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第6期717-717,共1页
Recently, we received a letter from Prof. G. L. Oppo, which indicated that he had doubts about the transformation of the system in the article Chin. Phys. B 31 060503 (2022) and gave other considerations. After inspec... Recently, we received a letter from Prof. G. L. Oppo, which indicated that he had doubts about the transformation of the system in the article Chin. Phys. B 31 060503 (2022) and gave other considerations. After inspection, we found that there was a clerical error in the article. Based on this, we have made corrections and supplements to the original article. 展开更多
关键词 conservative flows dissipative attractors coexisting phenomena class-B laser chaotic system
下载PDF
Coexistence of giant Rashba spin splitting and quantum spin Hall effect in H–Pb–F
4
作者 薛文明 李金 +3 位作者 何朝宇 欧阳滔 戴雄英 钟建新 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期414-418,共5页
Rashba spin splitting(RSS)and quantum spin Hall effect(QSHE)have attracted enormous interest due to their great significance in the application of spintronics.In this work,we theoretically proposed a new two-dimension... Rashba spin splitting(RSS)and quantum spin Hall effect(QSHE)have attracted enormous interest due to their great significance in the application of spintronics.In this work,we theoretically proposed a new two-dimensional(2D)material H–Pb–F with coexistence of giant RSS and quantum spin Hall effec by using the ab initio calculations.Our results show that H–Pb–F possesses giant RSS(1.21 eV·A)and the RSS can be tuned up to 4.16 e V·A by in-plane biaxial strain,which is a huge value among 2D materials.Furthermore,we also noticed that H–Pb–F is a 2D topological insulator(TI)duo to the strong spin–orbit coupling(SOC)interaction,and the large topological gap is up to 1.35 e V,which is large enough for for the observation of topological edge states at room temperature.The coexistence of giant RSS and quantum spin Hall effect greatly broadens the potential application of H–Pb–F in the field of spintronic devices. 展开更多
关键词 coexistENCE Rashba spin splitting quantum spin Hall effect spin–orbit coupling
下载PDF
Some of the Mechanisms for Coexistence of Tree Species Diversity in Tropical Forests: A Review of Effects of Tree Density Dependence
5
作者 Oladele Fisayo Falade 《Open Journal of Forestry》 2023年第1期132-144,共13页
Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur seque... Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively. 展开更多
关键词 Tree Community Structure Tree Species Diversity Tree Species coexistence Tree Populations
下载PDF
Inferring Human-elephant Coexistence Based on Characteristics of Human-elephant Interactions in Nangunhe of Yunnan,China
6
作者 WANG Jiahui CHEN Ying +2 位作者 SUN Yakuan LYU Zhuoluo SHI Kun 《Chinese Geographical Science》 SCIE CSCD 2023年第2期363-376,共14页
Human-wildlife conflict(HWC)negatively impacts both humans and wildlife.Attitudes of local residents have been critical in promoting wildlife conservation.It is therefore necessary to understand the characteristics of... Human-wildlife conflict(HWC)negatively impacts both humans and wildlife.Attitudes of local residents have been critical in promoting wildlife conservation.It is therefore necessary to understand the characteristics of HWC and identify influential factors on attitudes towards conservation to implement conservation strategies efficiently.This research focused on features of human-elephant interactions,while attitudes and values regarding the small population of Asian elephants(Elephas maximus)in Nangunhe National Nature Reserve(NNR),Yunnan,China.The total of 327 valid questionnaires were gathered around the area where Asian elephants were distributed.Logistic regression models were employed to analyze the correlations among five predictor variables(‘Area’,‘Family size’,‘Annual income’,‘Quantity of family members in non-primary industries’and‘Experiencing loss or not’)and three response variables(‘Attitude towards elephants’,‘Perception of the values of elephants’and‘Attitude towards tourism development’).The study area was densely forested with tea plants,rubber trees,corns and sugarcane.There,25.99%of respondents reported the experience of human-elephant conflict(HEC),with crop raiding and cash crop damages being the major conflict types.To demonstrate respect for elephants and to mitigate HEC,a unique custom called‘Giving tribute to elephants’was developed long ago.Respondents’township with an official annual festival of‘Giving Tribute to Elephants’(odds ratio(OR)=2.75,P=1.73×10^(-6))and higher annual income(OR=2.09,P=5.45×10^(-5))significantly contributed to forming a more positive attitude towards elephants,whereas HEC itself have contributed to a more negative attitude(OR=0.50,P=3.29×10^(-3)).Therefore,we propose that:1)reducing human-elephant conflict by testing multiple mitigation measures and adopting the most effective one of them;2)enhancing local livelihoods through the development of ecological products and ecotourism;and 3)preserving and developing the Wa culture in this region.The study area deserves more attention and further research to explore and obtain endorsement from the public to achieve coexistence between human and wildlife. 展开更多
关键词 Asian elephant(Elephas maximus) Wa people human-elephant conflict coexistENCE Nangunhe National Nature Reserve YUNNAN China
下载PDF
Protection and Restoration of Soil and Water Ecology to Achieve Harmonious Coexistence between Human and Nature
7
作者 SUN Fazheng 《Journal of Landscape Research》 2023年第1期60-62,共3页
At present,the ecological environment crisis of global concern,such as climate warming and biodiversity loss,the fundamental reason is the change and destruction of the earth's soil and water ecology.Therefore,pro... At present,the ecological environment crisis of global concern,such as climate warming and biodiversity loss,the fundamental reason is the change and destruction of the earth's soil and water ecology.Therefore,protecting and restoring the authenticity,diversity,cleanliness and integrity of soil and water ecology,we should coordinate and deal with the relationship between human beings and soil and water ecology,and realize the harmonious coexistence between human beings and nature from the three aspects of protecting natural soil and water ecology,protecting and restoring natural soil and water ecology,building and regenerating artificial soil and water ecology. 展开更多
关键词 Soil and water ecology PROTECTION RESTORATION Harmonious coexistence
下载PDF
从竞生走向共生:六堡茶传承中的多民族交往交流交融与互嵌式发展——铸牢中华民族共同体意识的广西实践系列之四 被引量:2
8
作者 郝国强 李星莹 《湖北民族大学学报(哲学社会科学版)》 北大核心 2024年第2期43-55,共13页
茶文化是中华优秀传统文化的重要组成部分,是各民族交往交流交融的载体和结晶。六堡茶是岭南地区的特色茶,体现了瑶族与汉族饮食文化的共生之美。在六堡茶文化的变迁过程中,通过“舜帝南巡”“茶箩娘”等民间叙事,岭南先民对中华文化的... 茶文化是中华优秀传统文化的重要组成部分,是各民族交往交流交融的载体和结晶。六堡茶是岭南地区的特色茶,体现了瑶族与汉族饮食文化的共生之美。在六堡茶文化的变迁过程中,通过“舜帝南巡”“茶箩娘”等民间叙事,岭南先民对中华文化的认同得到延承;通过制茶技艺从瑶族内部家族传承到各民族间师徒传承方式的转变,区域社会中的族际关系从竞生最终走向共生。同时,当前六堡茶从“侨销茶”向“畅销茶”的发展转向有助于多民族互嵌式的产业共同体建设。在铸牢中华民族共同体意识的时代背景下,六堡茶已成为一种富有情感共鸣和精神认同的文化符号。 展开更多
关键词 六堡茶 竞生 共生 民族交往交流交融 互嵌式发展
下载PDF
Coexistence of diffuse large B-cell lymphoma,acute myeloid leukemia,and untreated lymphoplasmacytic lymphoma/waldenström macroglobulinemia in a same patient:A case report
9
作者 Liu-Bo Zhang Lu Zhang +8 位作者 Hong-Lei Xin Yan Wang Hong-Yu Bao Qing-Qi Meng Su-Yu Jiang Xue Han Wan-Ru Chen Jian-Ning Wang Xiao-Feng Shi 《World Journal of Clinical Cases》 SCIE 2023年第18期4295-4305,共11页
BACKGROUND The Coexistence of myeloid and lymphoid malignancies is rare.Myeloid leukemia occurs more frequently as a secondary event in patients receiving chemotherapy agents for lymphoid malignancies.Synchronous diag... BACKGROUND The Coexistence of myeloid and lymphoid malignancies is rare.Myeloid leukemia occurs more frequently as a secondary event in patients receiving chemotherapy agents for lymphoid malignancies.Synchronous diagnoses of diffuse large B-cell lymphoma(DLBCL),acute myeloid leukemia(AML),and untreated lymphoplasmacytic lymphoma/Waldenström macroglobulinemia(LPL/WM)in the same patient have not been reported.Here we report one such case.CASE SUMMARY An 89-year-old man had a chest wall mass histopathologically diagnosed as DLBCL.The bone marrow and peripheral blood contained two groups of cells.One group of cells fulfilled the criteria of AML,and the other revealed the features of small B lymphocytic proliferative disorder,which we considered LPL/WM.Multiple chromosomal or genetic changes were detected in bone marrow mononuclear cells,including ATM deletion,CCND1 amplification,mutations of MYD88(L265P)and TP53,WT1 overexpression,and fusion gene of BIRC2-ARAP1,as well as complex chromosomal abnormalities.The patient refused chemotherapy because of old age and died of pneumonia 1 mo after the final diagnosis.CONCLUSION The coexistence of DLBCL,AML,and untreated LPL/WM in the same patient is extremely rare,which probably results from multiple steps of genetic abnormalities.Asymptomatic LPL/WM might have occurred first,then myelodysplastic syndromerelated AML developed,and finally aggressive DLBCL arose.Therefore,medical staff should pay attention to this rare phenomenon to avoid misdiagnoses. 展开更多
关键词 Diffuse large B-cell lymphoma Acute myeloid leukemia Small B lymphocyte proliferative disorder Lymphoplasmacytic lymphoma/Waldenström macroglobulinemia coexistENCE Case report
下载PDF
Coexistence of Pseudotumor Cerebri and Chiari Malformation Type 1
10
作者 BarışTen Celal Bağdatoğlu +2 位作者 Hasan HüsnüYüksek Gülhan Temel Yüksel Balcı 《Proceedings of Anticancer Research》 2023年第6期13-20,共8页
Objective:To identify different radiological markers for the diagnosis of the coexistence of pseudotumor cerebri and Chiari malformation type 1.Method:Patients who were clinically suspected to have Chiari malformation... Objective:To identify different radiological markers for the diagnosis of the coexistence of pseudotumor cerebri and Chiari malformation type 1.Method:Patients who were clinically suspected to have Chiari malformation type 1 and were referred to the Department of Radiology between 2007 and 2020,and whose diagnosis was radiologically confirmed through magnetic resonance imaging(MRI),were retrospectively evaluated.A total of 49 Chiari malformation type 1 patients with both cervical and cerebral examinations and 49 control subjects of the same age and gender without a diagnosis of Chiari malformation type 1 were included in the study.In Chiari malformation type 1 diagnosed patients,the presence of pseudotumor cerebri,the presence of syringomyelia in cervical spinal MRI images,and the distance of cerebellar tonsils and obex according to McRae line were evaluated in millimeters.Result:In Chiari malformation type 1 clinically and radiologically diagnosed cases,the cerebellar tonsils and obex were located lower in patients with a radiological diagnosis of pseudotumor cerebri compared to those without,and the rate of accompanying syringomyelia appeared to be higher.However,no statistically significant difference was observed between the two groups.Conclusion:The coexistence of pseudotumor cerebri and Chiari malformation type 1 is more common than previously estimated.Different treatment protocols in the coexistence of pseudotumor cerebri and Chiari malformation type 1 emphasize the importance of making this diagnosis.Further radiological imaging studies are needed to identify different radiological markers for the diagnosis of the coexistence of pseudotumor cerebri and Chiari malformation type 1. 展开更多
关键词 Pseudotumor cerebri Chiari malformation type 1 coexistENCE Radiological markers
下载PDF
中国式现代化的形态建构、动力要素与实践进路——以人与自然和谐共生为分析视角 被引量:3
11
作者 王雨辰 张熊 《新疆师范大学学报(哲学社会科学版)》 北大核心 2024年第3期7-15,F0002,共10页
中国式现代化是中国共产党立足人类文明和现代化发展规律,坚持把马克思主义基本原理同中国具体实际相结合、同中华优秀传统文化相结合的重大成果,超越了西方现代化道路与模式。文本以人与自然和谐共生为视角展开对中国式现代化的形态建... 中国式现代化是中国共产党立足人类文明和现代化发展规律,坚持把马克思主义基本原理同中国具体实际相结合、同中华优秀传统文化相结合的重大成果,超越了西方现代化道路与模式。文本以人与自然和谐共生为视角展开对中国式现代化的形态建构,从政治领导力量、文化因素、经济因素、制度因素和技术因素等方面探讨实现中国式现代化的动力要素;指出中国式现代化的推进始终坚持中国共产党领导,坚持中国特色社会主义,坚持以人民为中心的发展思想,坚持人与自然和谐共生,走生态文明发展的现代化新道路,追求“五个文明”相协调和全体人民共同富裕的价值目标,既为后发国家独立自主实现现代化提供了全新选择,又创造出人类文明新形态。 展开更多
关键词 中国共产党 中国式现代化 人与自然和谐共生 动力要素 实践进路
下载PDF
多病共存慢性病患者内脏康复的研究进展
12
作者 李丹 肖卫忠 +3 位作者 韩庆烽 刘小璇 刘小燮 杨振华 《医学综述》 CAS 2024年第4期465-471,共7页
随着慢性病发病率及患病率逐年增加,多病共存现象日益普遍。内脏康复是以运动为主的一种综合性干预手段,可以改善慢性病患者的脏器功能,提高其生活质量。目前多病共存慢性病患者的内脏康复尚处于探索阶段。多病共存慢性病患者行内脏康... 随着慢性病发病率及患病率逐年增加,多病共存现象日益普遍。内脏康复是以运动为主的一种综合性干预手段,可以改善慢性病患者的脏器功能,提高其生活质量。目前多病共存慢性病患者的内脏康复尚处于探索阶段。多病共存慢性病患者行内脏康复前需进行一系列评估,基于国际功能、残疾和健康分类模式构建以功能学分类为基础的内脏康复评估体系可能是未来的发展方向。多病共存慢性病患者运动处方的制订需更加关注安全性、有效性和依从性,而最低限度标准化运动处方可能作为个性化运动处方的替代方案。 展开更多
关键词 多病共存 慢性病 内脏康复
下载PDF
鄂尔多斯盆地庆阳气田二叠系山西组山_(1)^(3)沉积相类型论证
13
作者 王龙 李娅 +3 位作者 董倩云 范倩倩 刘平 单敬福 《科学技术与工程》 北大核心 2024年第18期7510-7526,共17页
鄂尔多斯盆地庆阳气田山1段是其主力产层,其沉积环境及其相类型一直争议较多,不同认识导致各个沉积相域内砂体对比模式和砂体分布形态存在着一定差异,从而给勘探井位部署增加了难度。在前人研究成果基础上,综合地震、测井、岩心、露头... 鄂尔多斯盆地庆阳气田山1段是其主力产层,其沉积环境及其相类型一直争议较多,不同认识导致各个沉积相域内砂体对比模式和砂体分布形态存在着一定差异,从而给勘探井位部署增加了难度。在前人研究成果基础上,综合地震、测井、岩心、露头及室内分析化验等资料,结合地震反射结构揭示的溯源退覆特征、岩心显示的岩性粒度与层理构造、测井沉积旋回特征、现代沉积学的比较等等多视角证据链,对该区山_(1)^(3)小层的沉积相进行了详细论证、分析和描述。研究结果表明,研究区岩性以中粗砂岩为主,多发育块状、板状及小型槽状交错层理,测井相既有河流“二元结构”发育完整的井段,也有只发育下部粗粒端元河流“二元结构”发育不完整的井段,前者揭示发育曲流河,后者则与辫状河发育有关;粒度分析结果显示主要以跳跃粒度成分为主,说明古水动力强;研究区周边露头资料显示既有曲流河发育也有辫状河发育,说明山1段沉积期曲流河和辫状河是同期存在的;现代卫星照片揭示,曲流河和辫状河共生共存发育是普遍存在的,综合上述证据,最终确定研究区山31发育相类型为河流相,且表现为曲辫共存特征,曲流河的频繁侧积以及平面多种河型共存,垂向河道的多期叠置是导致砂体分布复杂化和横向相变化快速的主控因素。 展开更多
关键词 庆阳气田 曲辫共存 野外露头 沉积模式
下载PDF
两种油管钢在模拟油田高温高压O_(2)-CO_(2)地层水环境中的腐蚀行为
14
作者 宋文文 谢俊峰 +7 位作者 赵密锋 袁军涛 冯文昊 谭凤玲 李轩鹏 辛通 张慧慧 付安庆 《腐蚀与防护》 CAS CSCD 北大核心 2024年第7期14-23,共10页
氧气与二氧化碳共存环境的腐蚀已成为油田注入井况中金属材料损伤的主要诱因。采用高温高压釜模拟了西部某油田注入井工况(O_(2)-CO_(2)共存环境),通过腐蚀失重试验、点蚀三维形貌分析、腐蚀产物显微分析等方法研究了P110和3Cr两种油管... 氧气与二氧化碳共存环境的腐蚀已成为油田注入井况中金属材料损伤的主要诱因。采用高温高压釜模拟了西部某油田注入井工况(O_(2)-CO_(2)共存环境),通过腐蚀失重试验、点蚀三维形貌分析、腐蚀产物显微分析等方法研究了P110和3Cr两种油管钢在高温高压、O_(2)-CO_(2)共存的高矿化度地层水环境中的腐蚀行为。结果表明:两种油管钢在O_(2)-CO_(2)共存环境中遭受了严重的均匀腐蚀和局部腐蚀;在90~150℃内,两种材料的腐蚀随温度升高而加剧,均匀腐蚀速率增幅达79.7%,最大点蚀速率的增幅达143.4%;O_(2)与CO_(2)共存时,阴极反应显著加快,加速了保护性较差的铁氧化物的形成,导致严重的均匀腐蚀和局部腐蚀,而低Cr钢中的Cr不足以改善腐蚀产物膜的保护性,使该钢不能适应O_(2)-CO_(2)共存环境。 展开更多
关键词 注入井 O_(2)-CO_(2)共存 腐蚀 油管钢 局部腐蚀
下载PDF
电磁感应下分数阶神经网络动力学行为分析及应用
15
作者 丁大为 王谋媛 +3 位作者 王金 杨宗立 牛炎 王威 《物理学报》 SCIE EI CAS CSCD 北大核心 2024年第10期59-71,共13页
忆阻器可以用来模拟生物神经突触和描述电磁感应效应.为了探索电磁感应作用下异构神经网络的动力学行为,本文首先使用双局部有源忆阻器耦合一个Hindmarsh-Rose (HR)和两个FitzHugh-Nagumo (FN)神经元,构成忆阻电磁感应下分数阶异构神经... 忆阻器可以用来模拟生物神经突触和描述电磁感应效应.为了探索电磁感应作用下异构神经网络的动力学行为,本文首先使用双局部有源忆阻器耦合一个Hindmarsh-Rose (HR)和两个FitzHugh-Nagumo (FN)神经元,构成忆阻电磁感应下分数阶异构神经网络.然后利用相图、分岔图、李雅普诺夫指数谱和吸引盆等动力学分析方法,对该网络进行数值研究.结果表明该神经网络表现出丰富的动力学行为,包括共存行为、反单调现象、瞬态混沌和放电行为等,为研究人脑放电行为提供支持,随后进一步利用时间反馈控制方法实现了双稳态的控制.最后,在嵌入式硬件平台上实现了该神经网络,验证了仿真结果的有效性. 展开更多
关键词 忆阻电磁感应 分数阶神经网络 吸引子共存 反单调性
下载PDF
齿轮传动系统共存吸引子的稳定性与分岔
16
作者 金花 王才林 吕小红 《噪声与振动控制》 CSCD 北大核心 2024年第4期50-55,124,共7页
以3自由度齿轮传动系统为研究对象,应用数值仿真方法得到系统的多初值分岔图,结合最大Lyapunov指数(Top Lyapunov Exponent,TLE)分析阻尼系数对系统动力学特性的影响。将数值仿真、延拓打靶法和Floquet特征乘子相结合,延拓追踪共存吸引... 以3自由度齿轮传动系统为研究对象,应用数值仿真方法得到系统的多初值分岔图,结合最大Lyapunov指数(Top Lyapunov Exponent,TLE)分析阻尼系数对系统动力学特性的影响。将数值仿真、延拓打靶法和Floquet特征乘子相结合,延拓追踪共存吸引子的稳定性与分岔。应用胞映射法计算共存吸引子的吸引域,结合分岔图、相图和Poincaré映射图揭示共存吸引子的吸引域随系统参数变化的侵蚀演变过程。结果表明:系统存在周期倍化分岔点和鞍结分岔点之间的距离非常近的现象,鞍结分岔使系统终态在两个不同的周期运动之间跳跃,使周期倍化分岔表现出亚临界特性;共存的周期吸引子主要由鞍结分岔引起;若鞍结分岔发生在概周期运动区间,则会出现周期吸引子与概周期吸引子共存。 展开更多
关键词 振动与波 齿轮传动系统 Floquet乘子 共存吸引子 稳定性
下载PDF
一种新型复合指数型局部有源忆阻器耦合的Hopfield神经网络
17
作者 王梦蛟 †杨琛 +1 位作者 贺少波 李志军 《物理学报》 SCIE EI CAS CSCD 北大核心 2024年第13期52-63,共12页
由忆阻耦合的神经网络模型,因其能更真实地反映生物神经系统的复杂动力学特性而被广泛研究.目前用于耦合神经网络的忆阻器数学模型主要集中在一次函数、绝对值函数、双曲正切函数等,为进一步丰富忆阻耦合神经网络模型,且考虑到一些掺杂... 由忆阻耦合的神经网络模型,因其能更真实地反映生物神经系统的复杂动力学特性而被广泛研究.目前用于耦合神经网络的忆阻器数学模型主要集中在一次函数、绝对值函数、双曲正切函数等,为进一步丰富忆阻耦合神经网络模型,且考虑到一些掺杂半导体中粒子的运动规律,设计了一种新的复合指数型局部有源忆阻器,并将其作为耦合突触用于Hopfield神经网络,利用基本的动力学分析方法,研究了系统在不同参数下的动力学行为,以及在不同初始值下多种分岔模式共存的现象.实验结果表明,忆阻突触内部参数对系统具有调控作用,且该系统拥有丰富的动力学行为,包括对称吸引子共存、非对称吸引子共存、大范围的混沌状态和簇发振荡等.最后,用STM32单片机对系统进行了硬件实现. 展开更多
关键词 局部有源忆阻器 HOPFIELD神经网络 多种共存吸引子 簇发振荡
下载PDF
文化符号的传播与共享——以夏鲁寺、贡嘎曲德寺日月图像为例
18
作者 吕岩 岳燕 张会庆 《西北民族大学学报(哲学社会科学版)》 北大核心 2024年第3期156-165,共10页
西藏地区的夏鲁寺与贡嘎曲德寺壁画中均出现了以金乌、玉兔代表日与月的图像。金乌与玉兔图像是中原文化用来表示日与月的固定图式。自汉朝时期由西王母神话与民间信仰不断糅合产生,唐代时被吸收进佛教图像体系中,后期随着藏传佛教的兴... 西藏地区的夏鲁寺与贡嘎曲德寺壁画中均出现了以金乌、玉兔代表日与月的图像。金乌与玉兔图像是中原文化用来表示日与月的固定图式。自汉朝时期由西王母神话与民间信仰不断糅合产生,唐代时被吸收进佛教图像体系中,后期随着藏传佛教的兴盛与文化交流的频繁,藏传佛教绘画吸收了这种日月图像母题。西藏壁画艺术中的日月图像,不仅更新了藏传佛教艺术的表达范式,而且图像意义也突破了单纯宗教艺术的阐释,凸显了中央皇权的在场。夏鲁寺与贡嘎曲德寺壁画中的日月图像是汉藏文化交往交流交融的结果,彰显了元明时期各民族之间的频繁互动,以及多元文化交流下文化符号互融互生的整体性社会结构。 展开更多
关键词 日月图像 文化符号 互融互生 交往交流交融
下载PDF
面向一致覆盖的无蜂窝和传统蜂窝共存网络AP部署优化
19
作者 姜静 陶莎 +3 位作者 王伟 褚宏云 Worakrin Sutthiphan 李春国 《电子与信息学报》 EI CAS CSCD 北大核心 2024年第6期2352-2360,共9页
为了解决传统蜂窝网络中用户体验剧烈波动的问题,无蜂窝和传统蜂窝共存网络将大量接入点(Access Point,AP)部署到传统蜂窝网络中,显著改善边缘用户和盲区的覆盖信号质量。因此用户在覆盖区域的任何位置均获得良好、一致的用户体验,即一... 为了解决传统蜂窝网络中用户体验剧烈波动的问题,无蜂窝和传统蜂窝共存网络将大量接入点(Access Point,AP)部署到传统蜂窝网络中,显著改善边缘用户和盲区的覆盖信号质量。因此用户在覆盖区域的任何位置均获得良好、一致的用户体验,即一致覆盖是提升共存网络性能的首要目标。而AP部署方案是共存网络中用户传输速率和覆盖的决定性因素,该文提出了面向一致覆盖的AP部署优化方法。首先根据共存网络的联合传输模型推导得到用户的下行可达速率,然后以最大化平均吞吐量为目标,将AP部署建模为比率和规划问题,并基于分式规划和引入辅助变量将其转换为凸优化问题,进而通过迭代求解AP的最优位置。仿真结果表明,相比传统蜂窝网络,所提方案可显著提高边缘和盲区的平均吞吐量。 展开更多
关键词 无线通信 无蜂窝和传统蜂窝共存网络 一致覆盖 联合传输 AP部署
下载PDF
相变腔冷凝现象对沸腾-凝结共存相变传热的影响
20
作者 李艳霞 史壮壮 刘中良 《北京工业大学学报》 CAS CSCD 北大核心 2024年第1期113-122,共10页
针对平板热管均热器内部狭小空间存在着强烈的沸腾与凝结相互作用,以去离子水为工质,可视化实验研究了冷凝面上发生的凝结现象及其对相变腔传热性能的影响。通过分析冷凝面上液滴的形成、长大、汇聚成液膜、滴落,以及气液界面产生气泡... 针对平板热管均热器内部狭小空间存在着强烈的沸腾与凝结相互作用,以去离子水为工质,可视化实验研究了冷凝面上发生的凝结现象及其对相变腔传热性能的影响。通过分析冷凝面上液滴的形成、长大、汇聚成液膜、滴落,以及气液界面产生气泡随气流运动对冷凝液膜的冲刷作用,揭示了不同热流密度和充液率时相变腔冷凝面传热传质特性对沸腾-凝结共存相变传热影响的内在机理。实验结果表明:受重力影响,水蒸气在冷凝面上凝结有液滴和液膜共存并相互转化的特性,冷凝面热阻在相变腔总热阻中占比65%~88%,适宜的充液率有利于沸腾气泡冲刷冷凝壁面,加快冷凝液的回流,改善冷凝面及相变腔的传热性能;随着热流密度的增大,沸腾过程变得剧烈,冷凝面受沸腾气泡的冲刷频率提高,冷凝液回流速度加快,冷凝面热阻减小,传热性能得到提高。 展开更多
关键词 可视化 相变腔 凝结与沸腾共存 充液率 气泡冲刷 冷凝液回流
下载PDF
上一页 1 2 172 下一页 到第
使用帮助 返回顶部