检索结果-南通市图书馆

A DYNAMIC MODEL OF THE TWO-ROUTE TRAFFIC FLOW

在线全文

学校读者我要写书评

暂无评论

A DYNAMIC MODEL OF THE TWO-ROUTE TRAFFIC FLOW

地理大数据揭示中国主要城市建成环境物质存量的空间格局

第一届交通运输工程国际学术会议

作者： T. Q. tang1 2 C. Q. Mei2 3 and H. J. huang2# 1Department of Automobile engineering Beijing University of Aeronautics and Astronautics Beijing china 2school of Management Beijing University of Aeronautics and Astronautics Beijing china 3school of Statistics Capital University of Economics and Business Beijing china

So far, various traffic flow models have been developed for reproducing and explaining some complex traffic phenomena, e.g., stop-and-go traffic, phase transition, local cluster, traffic waves （shock wave, rarefaction wave, soliton wave and kink wave）, lane-changing, overtaking and others. Most of these models are subject to the traffic on highways, rather than that on networks. On the other hand, the studies associated with networks mainly address the macro issues of traffic flows, for example, the modeling of route and departure time choices. These network models are difficult to explain the micro properties of traffic flows in a network. Therefore, it is interesting to develop a modeling approach which can considers the micro and macro points of traffic flow simultaneously. Some researchers have recently extended the kinematic model and cellular automata model to describe the network flow. The kinematic model doesn’t take into account momentum equation and the cellular automata model is based on simulation. In this paper, we present a dynamic model to formulate the network flow. A simple network with two routes and one O-D pair is selected as the modeling object. Numerical results show that our model can well reproduce the evolution of the inflow, outflow and the flow on each link when a small perturbation of the arrival of private vehicles appears.

关键词： Dynamic model Traffic flow Two-route network

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

engineering 2024年第3期34卷 143-153页

作者： Zhou huang Yi Bao Ruichang Mao Han Wang Ganmin Yin Lin Wan Houji Qi Qiaoxuan Li Hongzhao tang Qiance Liu Linna Li Bailang Yu Qinghua Guo Yu Liu huadong Guo Gang Liu institute of Remote Sensing and Geographical Information Systems School of Earth and Space SciencesPeking UniversityBeijing 100871China International Research Center of Big Data for Sustainable Development Goals Beijing 100094China SDU Life Cycle engineering Department of Green TechnologyUniversity of Southern DenmarkOdense 5230Denmark Department of Construction Management School of Civil EngineeringTsinghua UniversityBeijing 100084China school of Computer Science China University of GeosciencesWuhan 430074China school of Geographical Sciences East China Normal UniversityShanghai 200062China Land Satellite Remote Sensing Application Center Ministry of Natural ResourcesBeijing 100048China institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Department of Geography California State UniversityLong BeachCA 90840USA Aerospace Information Research institute Chinese Academy of SciencesBeijing 100094China College of Urban and Environmental Sciences Peking UniversityBeijing 100871China

The patterns of material accumulation in buildings and infrastructure accompanied by rapid urbanization offer an important,yet hitherto largely missing stock perspective for facilitating urban system engineering and informing urban resources,waste,and climate ***,our existing knowledge on the patterns of built environment stocks across and particularly within cities is limited,largely owing to the lack of sufficient high spatial resolution *** study leveraged multi-source big geodata,machine learning,and bottom-up stock accounting to characterize the built environment stocks of 50 cities in china at 500 m fine-grained *** per capita built environment stock of many cities(2.1.tonnes per capita on average)is close to that in western cities,despite considerable disparities across cities owing to their varying socioeconomic,geomorphology,and urban form *** is mainly owing to the construction boom and the building and infrastructure-driven economy of china in the past ***’s urban expansion tends to be more“vertical”(with high-rise buildings)than“horizontal”(with expanded road networks).It trades skylines for space,and reflects a concentration-dispersion-concentration pathway for spatialized built environment stocks development within cities in *** results shed light on future urbanization in developing cities,inform spatial planning,and support circular and low-carbon transitions in cities.

关键词： Urban system engineering Built environment stock Spatial pattern Urban sustainability Big geodata

煤直接液化航空煤油自着火特性实验及动力学研究

在线全文

学校读者我要写书评

暂无评论

推进技术 2024年第8期45卷 104-111页

作者：武颖韬孔祥东王新辉梁金虎汤成龙黄佐华汪必耀曾萍西安交通大学能源与动力工程学院陕西西安710049 中北大学环境与安全工程学院山西太原030051 中国民航局第二研究所四川成都610041 中国民用航空航油航化适航审定中心四川成都610041

煤直接液化(DCL)航空煤油含有大量的环烷烃,与传统航空煤油成分差异较大,研究DCL煤油的着火特性及反应动力学对于深入认识其燃烧性能及其推广应用具有重要意义。因此,本文使用快速压缩机测量了DCL煤油,RP-3煤油及其混合物在不同当量比... 详细信息

煤直接液化(DCL)航空煤油含有大量的环烷烃,与传统航空煤油成分差异较大,研究DCL煤油的着火特性及反应动力学对于深入认识其燃烧性能及其推广应用具有重要意义。因此,本文使用快速压缩机测量了DCL煤油,RP-3煤油及其混合物在不同当量比和压力下的着火延迟期,对比了DCL与RP-3煤油的燃烧放热及相对反应活性,分析了二者低温反应活性差异的动力学机制。使用实验数据验证了文献中DCL煤油的化学反应动力学模型,并通过构建替代物组分中正戊基环己烷的化学反应机理,提高了模型对DCL煤油着火延迟和高温裂解产物的预测性能。研究结果表明,DCL煤油的着火放热量更高,其着火延迟期在高温下(>1000 K)与RP-3接近,而在低温下(<750 K)则略高于RP-3。DCL煤油中大量的环烷烃成分阻碍了燃料分子低温链分支反应的进行,抑制了其低温反应活性,有利于降低燃料进入主燃区前发生自燃的倾向。

关键词：煤直接液化航空煤油着火延迟期正戊基环己烷化学反应动力学

High-performance BiFeO_(3)eBaTiO_(3)lead-free piezoceramics insensitive to off-stoichiometry and processing temperature

在线全文

学校读者我要写书评

暂无评论

Journal of Materiomics 2023年第2期9卷 353-361页

作者： Yu-Cheng tang Yang Yin ai-Zhen Song He-Zhang Li Bo-ping Zhang school of Materials Science and engineering University of Science and Technology BeijingBeijing100083China National institute for Materials Science(NIMS)1-2.1.Sengen TsukubaIbaraki305-0047Japan

It is well-known that the performance of BiFeO3eBaTiO3(BF-BT)ceramics is sensitive to composition,calcining and sintering temperature(Tcal and Tsint)due to the formation of Bi25FeO39 and/or Bi2Fe4O9 impurities and/or the volatilization of Bi_(2)O_(3).We report remarkably stable electrical properties over the range of0.03≤x≤0.05 and 930℃≤Tsint≤970C in 0.7Bi(1þx)FeO_(3)-0.3BaTiO_(3)ceramics prepared by one-step *** method avoids the thermodynamically unstable region of BiFeO_(3)and prevents the formation of Bi25FeO39 and/or Bi_(2)Fe_(4)O_(9)impurities even when the addition of a-Bi_(2)O_(3)raw material is intentionally deficient or rich to make off-stoichiometric BF-BT,thus greatly improving the robustness of compositional and ***-pseudocubic phase coexists in all ceramics,and their CR/CPC fraction are 48.0/52.0e50.6/49.4 and 55.9/44.1e56.6/43.4 when x increases from0.05≤x≤0 to 0.01≤x≤*** stable electrical properties of d33¼180e205 pC/N,Pr¼17.9e23.8 mC/cm^(2),and TC¼485e518℃are *** maximum d_(33T)/d_(33RT)of BF-BT is twice that of soft PZT,superior to most the-state-of-art lead-free *** results provide a synthesis strategy for designing high performance piezoelectric materials with good stability and easy industrialization.

关键词： BiFeO_(3)-BaTiO_(3) Lead-free ceramics One-step process Electrical properties Thermal stability

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

人工智能辅助含能分子设计的应用与展望

含能材料 2024年第4期32卷 408-421页

作者：刘锐刘建唐岳川张朝阳黄静黄鑫中国工程物理研究院化工材料研究所四川绵阳621999 西南石油大学化学化工学院四川成都610500

含能分子研发面临多重挑战,传统“试错法”效率低下,计算机辅助分子设计的出现改变了研发模式。本综述回顾了含能分子设计的发展历程,介绍了计算机辅助含能分子设计的研究现状,并概述了人工智能技术(ai)在性质预测、分子生成、合成路线... 详细信息

含能分子研发面临多重挑战,传统“试错法”效率低下,计算机辅助分子设计的出现改变了研发模式。本综述回顾了含能分子设计的发展历程,介绍了计算机辅助含能分子设计的研究现状,并概述了人工智能技术(ai)在性质预测、分子生成、合成路线和反应条件预测等多个设计环节的最新进展,讨论了当前含能分子设计模式与其他材料设计方法的差距,思考差距产生的原因,并对未来ai辅助含能分子设计的发展方向提出展望。研究发现,ai在含能分子性能预测和分子生成等方面已经有了应用,但在合成路径规划和反应条件优化等环节的应用仍有待进一步探索,应用前景巨大。通过数据增强、迁移学习或高通量计算有望能够解决含能分子数据薄弱的问题;加强ai辅助含能分子合成路线与反应条件探索有望贯通“设计→评估→制备→验证”全流程自动化分子设计模式。ai辅助含能分子设计为提升含能分子设计水平提供新的可能性,有助提升含能分子研发效率。

关键词：含能分子分子设计人工智能机器学习定量构效关系

硬质聚氨酯泡沫/可膨胀石墨复合材料制备及阻燃性能研究

在线全文

学校读者我要写书评

暂无评论

塑料工业 2018年第9期46卷 108-112页

作者：周子健姜浩浩崔爱华刘新亮陈均唐刚安徽工业大学建筑工程学院安徽马鞍山243032 江苏绿源新材料有限公司江苏南通226003 安徽工业大学化学化工学院安徽马鞍山243032

以可膨胀石墨(EG)为阻燃剂,采用一步法全水发泡制备一系列硬质聚氨酯泡沫/可膨胀石墨复合材料(RPUF/EG),采用扫描电镜(SEM)、热重分析(TG)、极限氧指数(LOI)、UL94垂直燃烧、微型量热(MCC)、锥形量热(CONE)研究可膨胀石墨对硬质聚氨酯泡... 详细信息

以可膨胀石墨(EG)为阻燃剂,采用一步法全水发泡制备一系列硬质聚氨酯泡沫/可膨胀石墨复合材料(RPUF/EG),采用扫描电镜(SEM)、热重分析(TG)、极限氧指数(LOI)、UL94垂直燃烧、微型量热(MCC)、锥形量热(CONE)研究可膨胀石墨对硬质聚氨酯泡沫(RPUF)泡孔结构、热稳定性、阻燃性能以及燃烧性能的影响。研究表明,可膨胀石墨的加入降低了RPUF/EG降解温度,但会提高其高温稳定性; 30份可膨胀石墨使得RPUF/EG30达到UL94 V-1级别,极限氧指数达到25. 2%; 10份可膨胀石墨使得RPUF/EG10热释放速率峰值(PHRR)相对于纯RPUF下降26. 2%,并有效提高复合材料火灾安全性。

关键词：硬质聚氨酯泡沫可膨胀石墨复合材料阻燃热稳定性

Simultaneous improvement in strength and ductility of extruded Mg alloy via novel closed forging extrusion

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of china 2022年第9期32卷 2866-2876页

作者： Kun-ming ZHANG Chen QIN Jia SHE Xue-rui JING Peng PENG ai-tao tang Muhammad RASHAD Fu-sheng PAN College of Materials Science and engineering Chongqing UniversityChongqing 400044China National engineering Research Center for Mg Alloys Chongqing UniversityChongqing 400044China school of Metallurgy and Materials engineering Chongqing University of Science and TechnologyChongqing 401331China Bernal institute Department of Chemical SciencesUniversity of LimerickLimerickV94 T9PXIreland school of Materials Science and engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

A novel continuous plastic process employed on AZ31 Mg alloy called closed forging extrusion(CFE)was *** optical microscopy,scanning electron microscopy,electron back-scatter diffraction and tensile and compressive tests were employed to investigate the microstructure evolution and strengthening *** results indicated that the CFE-process can promote dynamic recrystallization(DRX),eliminate the coarsen unDRXed grain regions,refine the grains effectively,and improve the strength,plasticity and anisotropy of the *** grain refinement was mainly attributed to the stress,which facilitated the nucleation of recrystallization and refined the microstructure via the *** fully DRXed ultrafine grained structure improved the strength and plasticity *** 60 s closed forging and continuous extrusion,the alloy exhibits relatively high TYS,UTS,CYS,elongation and yield asymmetry of 305 MPa,337 MPa,295 MPa,27%and 0.97,respectively.

关键词： Mg alloys extrusion mechanical properties

基于改进遗传算法的多级关联资源协调调度技术

在线全文

学校读者我要写书评

暂无评论

北京理工大学学报 2017年第7期37卷 711-716页

作者：卢治兵王爱民唐承统北京理工大学机械与车辆学院北京100081

在实际生产调度中,存在一类人员、设备、夹具、刀具等多级资源共同参与调度的情况.与传统的机加调度不同,此类调度问题增加了人员、卡具、刀具的约束.文中提出了基于改进遗传算法的多级关联资源协调调度技术以解决此类问题.本技术主要... 详细信息

在实际生产调度中,存在一类人员、设备、夹具、刀具等多级资源共同参与调度的情况.与传统的机加调度不同,此类调度问题增加了人员、卡具、刀具的约束.文中提出了基于改进遗传算法的多级关联资源协调调度技术以解决此类问题.本技术主要包含应用遗传算法在满足匹配关系的多级资源之间进行动态组合,通过适应度计算保留质量好的多级资源组合及面向资源协调的多级资源工序调度时间处理,根据选定工序所需资源占用情况,寻找最早的工序插入的时间区域,并结合工程实例分析验证了该技术的有效性.

关键词：多级关联资源遗传算法资源动态组合作业调度协调调度约束

通过重氮盐分子表面修饰金纳米帽子探究其对等离子体共振吸收的影响

在线全文

学校读者我要写书评

暂无评论

光谱学与光谱分析 2019年第7期39卷 2073-2076页

作者：张爱堂王睿智崔亮刘敬权临沂大学材料科学与工程学院山东临沂276000 临沂国际学校山东临沂276000 青岛大学材料科学与工程学院石墨烯应用技术研究院山东青岛266071

以玻璃基底作为聚苯乙烯纳米球的载体,首先将聚苯乙烯纳米球旋涂在玻璃基底上,然后通过热沉积的方法将金熔融沉积在聚苯乙烯纳米粒子的表面,再通过超声的方式将负载有金纳米帽子的聚苯乙烯微球从玻璃基底上分离下来,最后用二氯甲烷将聚... 详细信息

以玻璃基底作为聚苯乙烯纳米球的载体,首先将聚苯乙烯纳米球旋涂在玻璃基底上,然后通过热沉积的方法将金熔融沉积在聚苯乙烯纳米粒子的表面,再通过超声的方式将负载有金纳米帽子的聚苯乙烯微球从玻璃基底上分离下来,最后用二氯甲烷将聚苯乙烯微球溶解掉,成功制备了空心的金纳米帽子材料。通过共价键链接的方式在这些空心的金纳米帽子的表面成功修饰上苯的衍生物,通过测试分析发现,修饰带有不同电性的基团,金纳米帽子的等离子体共振吸收会发生不同的红移或蓝移现象,推测这是由于金纳米帽子表面结构电子密度的变化所导致。

关键词：重氮盐分子金纳米帽子聚苯乙烯微球复合粒子