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Nonlocal Flocking Dynamics: Learning the Fractional Order of PDEs from Particle Simulations

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Communications on Applied Mathematics and Computation 2019年第4期1卷 597-619页

作者： Zhiping Mao zhen Li george Em Karniadakis Division of Applied Mathematics Brown UniversityProvidenceRI02912USA Pacific Northwest National Laboratory RichlandWA 99354USA

Flocking refers to collective behavior of a large number of interacting entities,where the interactions between discrete individuals produce collective motion on the large *** employ an agent-based model to describe the microscopic dynamics of each individual in a flock,and use a fractional partial differential equation(fPDE)to model the evolution of macroscopic quantities of *** macroscopic models with phenomenological interaction functions are derived by applying the continuum hypothesis to the microscopic *** of specifying the fPDEs with an ad hoc fractional order for nonlocal flocking dynamics,we learn the effective nonlocal influence function in fPDEs directly from particle trajectories generated by the agent-based *** demonstrate how the learning framework is used to connect the discrete agent-based model to the continuum fPDEs in one-and two-dimensional nonlocal flocking *** particular,a Cucker-Smale particle model is employed to describe the microscale dynamics of each individual,while Euler equations with nonlocal interaction terms are used to compute the evolution of macroscale *** trajectories generated by the particle simulations mimic the field data of tracking logs that can be obtained *** can be used to learn the fractional order of the influence function using a gaussian process regression model implemented with the Bayesian *** show in one-and two-dimensional benchmarks that the numerical solution of the learned Euler equations solved by the finite volume scheme can yield correct density distributions consistent with the collective behavior of the agent-based system solved by the particle *** proposed method offers new insights into how to scale the discrete agent-based models to the continuum-based PDE models,and could serve as a paradigm on extracting effective governing equations for nonlocal flocking dynamics directly from particle trajectories.

关键词： Fractional PDEs gaussian process Bayesian optimization Fractional Laplacian Conservation laws

Wettability of different clay mineral surfaces in shale:Implications from molecular dynamics simulations

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Petroleum Science 2023年第2期20卷 689-704页

作者： Kan-Yuan Shi Jun-Qing Chen Xiong-Qi Pang Fu-Jie Jiang Sha-Sha Hui zhen-Cheng Zhao Di Chen Qi Cong Tong wa.g Hui-Yi Xiao Xiao-Bin Yang Yu-Ying wa.g State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China College of geosciences China University of PetroleumBeijing102249China Basic Research Center for Energy Interdisciplinary College of ScienceChina University of PetroleumBeijing102249China Beijing Key Laboratory of Optical Detection Technology for Oil and gas College of ScienceChina University of PetroleumBeijing102249China

Shale contains a lot of clay minerals. Clay minerals mainly exist in nano- and micro-meter sized particles, and the pore structure is complex, which leads to its extremely complex wettability. The surface wettability of clay minerals significantly affects the oil and gas-bearing capacity of shale reservoirs. Therefore, studying the wettability of common clay minerals in shale at the nanoscale is of great significance for shale hydrocarbon exploration and development. In this study, the wetting behavior of water in n-hexane and toluene on different clay mineral surfaces at the nanoscale was systematically studied using Molecular dynamics (MD) simulation. And the influencing factors of wettability were analyzed. Through the analysis of the morphological changes of water, relative concentration of water, RDF and interaction energy, it is concluded that the following order of water wettability on the surfaces of clay minerals: montmorillonite > chlorite > kaolinite > illite. Through the analysis of interaction energy, it is concluded that the hydrophilicity of four clay minerals is stronger than that of lipophilicity. And the main interactions between water and oil and the mineral surfaces were van der waals force and electrostatic force. In addition, the temperature, liquid hydrocarbon type, and mineralization of water affected the wettability of clay minerals. The concentration of water on the surfaces of montmorillonite, kaolinite, and illite decreased with increasing temperature, and the water wettability decreased. At 298 K, the hydrophilicity of the surfaces of the clay minerals in toluene follows the order montmorillonite > chlorite > kaolinite > illite. The higher the NaHCO3 concentration in water, the weaker the wettability of the clay mineral surfaces to water. By comparing the previous experimental results with the MD simulation results, similar wetting characteristics were obtained, and the reliability of the simulation results was verified. MD simulation wa

关键词： Shale Molecular dynamics Nanoscale Wettability Clay minerals

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原子层沉积设备控制系统设计

化工自动化及仪表 2023年第1期50卷 68-73页

作者：毛娃陈焰刘振强昆明理工大学信息工程与自动化学院

以工控机与数字量输入输出板卡为基础,设计原子层沉积设备控制系统。采用工控机串行通信端口实现真空计、流量计、温度计等数据采集与控制。在N型单晶硅基底表面氧化铝薄膜生长测试中,生长300周期氧化铝薄膜平均厚度为33.84 nm,非均匀性... 详细信息

以工控机与数字量输入输出板卡为基础,设计原子层沉积设备控制系统。采用工控机串行通信端口实现真空计、流量计、温度计等数据采集与控制。在N型单晶硅基底表面氧化铝薄膜生长测试中,生长300周期氧化铝薄膜平均厚度为33.84 nm,非均匀性为0.36%,生长速率1.13A/cycle,达到氧化铝工艺标准。实验结果表明设备运行稳定可靠,满足实际工艺需要。

关键词：自控系统原子层沉积设备薄膜生长 C#语言工控机板卡

酪蛋白胶束乳液凝胶性质及其在大黄素负载中的应用

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食品与发酵工业 2023年第1期49卷 132-139页

作者：瓦文强秦娟娟杨敏魏彦明袁子文纪鹏甄晨波甘肃农业大学理学院甘肃兰州730070 甘肃农业大学动物医学院甘肃兰州730070

乳液凝胶可作为活性分子包封材料,具有安全性高、稳定性好等优点。该文以酪蛋白胶束和果胶为基质,以负载大黄素的大豆油为油相,制备了乳液凝胶,表征了凝胶微观结构,分析了其贮藏稳定性,研究了在模拟胃肠环境下凝胶对大黄素的缓释作用,... 详细信息

乳液凝胶可作为活性分子包封材料,具有安全性高、稳定性好等优点。该文以酪蛋白胶束和果胶为基质,以负载大黄素的大豆油为油相,制备了乳液凝胶,表征了凝胶微观结构,分析了其贮藏稳定性,研究了在模拟胃肠环境下凝胶对大黄素的缓释作用,并评价了凝胶体系的细胞毒性。结果表明,乳液凝胶为O/W型,随着果胶添加量的增加,油滴粒径减小。酪蛋白胶束与果胶体积比为8∶2和7∶3时,乳液凝胶在贮藏240 d时仍稳定。模拟胃肠消化实验表明,在模拟肠液累积消化240 min后,凝胶中大黄素的释放率大于游离大黄素释放率;当酪蛋白与果胶体积比为7∶3时,经CaCl_(2)处理后凝胶中大黄素的释放显著延缓,其360 min时释放量仅为(38.40±6.89)%。细胞实验表明,经凝胶负载后,大黄素的细胞毒性显著降低。

关键词：酪蛋白胶束果胶乳液凝胶大黄素缓释

Facile Chemical Conversion Synthesis and Luminescence Properties of Uniform YF3 Nanowires

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Chemical Research in Chinese Universities 2013年第1期29卷 1-5页

作者： XU zhen-he gAO Yu gE Xin SUN Yaguan College of Applied Chemistry Shenyang University of Chemical Technology Shenyang 110142 P. R. China" State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changehun 130022 P. R. China

Well-dispersed YF3 nanowires were synthesized by a designed hydrothermal conversion method with Y（OH）3 nanowires as precursor. Various equipments were used to characterize the samples. The results show that Y（OH）3 nanowires precursor was prepared through a simple hydrothermal process, which then served as the precursor for the fabrication of YF3 nanowires by a hydrothermal process. The whole process was carried out under aqueous conditions without any organic solvent, surfactant or catalyst. The conversion process from Y（OH）3 precursor to YF3 nanowires was investigated by time-dependent experiments. The possible formation mechanism of YF3 nanowires was presented in detail. Under UV excitation, 5%（mass fraction） Eu3＋ or 5%（mass fraction） Tb3＋ doped YF3 samples exhibit strong red or green emission, corresponding to the characteristic lines of Eu3＋ and Tb3＋, respectively. Moreover, the luminescence colors of the Eu3＋ and Tb3＋ codoped YF3 samples can be tuned from red, yellow and green-yellow to green by simply adjusting the relative doping concentrations of the activator ions under a single wa- velength excitation, which might find potential applications in the fields of, such as, light display systems and optoelectronic devices.

关键词： Luminescence Hydrothermal synthesis Rare earth Inorganic compound

Strong law of large numbers for supercritical superprocesses under second moment condition

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Frontiers of Mathematics in China 2015年第4期10卷 807-838页

作者： zhen-Qing CHEN Yan-Xia REN Renmlng SONg Rui ZHANg Department of Mathematics University of Washington Seattle WA 98195 USA LMAM School of Mathematical Sciences & Center for Statistical Science Peking University Beijing 100871 China Department of Mathematics University of Illinois Urbana IL 61801 USA LMAM School of Mathematical Sciences Peking University Beijing 100871 China

Consider a supercritical superprocess X = {Xt, t 〉~ O} on a locally compact separable metric space （E, m）. Suppose that the spatial motion of X is a Hunt process satisfying certain conditions and that the branching... 详细信息

关键词： Superprocess scaling limit theorem Hunt process spectral gap,h-transform martingale measure

Moisture transfer resistance method for liquid desiccant dehumidification analysis and optimization

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Chinese Science Bulletin 2010年第14期55卷 1445-1453页

作者： CHEN Lin CHEN Qun LI zhen gUO ZengYuan Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua University Beijing 100084 China

The concepts of entransy, entransy dissipation and transfer resistance are introduced into liquid desiccant dehumidification analysis to reveal the irreversibility and moisture transfer resistance between moist air and liquid *** analyzing a typical water (vapor) transfer process coupled with heat transfer, we define the concepts of mass entransy of water and its dissipation, derive the expression of moisture transfer resistance (MTR) that reflects the irreversibility of water transfer during dehumidification processes, and also point out the relationship between MTR and dehumidification performance. With these concepts, both adiabatic and internal cooling liquid desiccant dehumidification systems with various operation conditions are analyzed and optimized. It is found that for the adiabatic dehumidification system, increasing the mass transfer coefficient leads to the reduction of MTR, and consequently, the improvement of dehumidification performance. Meanwhile, for the dehumidification system with internal cooling, in order to reduce the MTR and improve the dehumidification performance, pre-cooling should be centralized ahead of the liquid desiccant inlet when the flow rates ratio of air to desiccant is small, whereas, uniform cooling should be applied when the flow rates ratio of air to desiccant is large.

关键词：液体干燥剂水分传输电阻法优化湿分液体除湿系统除湿性能空气流速

纳米银溶胶和微腔型光纤SERS基底的制备及其性能比较

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光谱学与光谱分析 2022年第2期42卷 470-477页

作者：付兴虎王振兴李佳轩马双玉付广伟金娃毕卫红董艳华燕山大学信息科学与工程学院河北省特种光纤与光纤传感重点实验室河北秦皇岛066004 特种光纤与光接入网省部共建重点实验室上海大学上海200444

通过化学法制备了纳米银溶胶基底和微腔型光纤表面增强拉曼散射(SERS)基底,其中光纤SERS基底的微腔结构是通过氢氟酸(HF)腐蚀得到的。实验采用湿法检测,首先将纳米银溶胶基底与罗丹明6g(R6g)混合,找到增强效果最强时的裸光纤微腔结构,... 详细信息

通过化学法制备了纳米银溶胶基底和微腔型光纤表面增强拉曼散射(SERS)基底,其中光纤SERS基底的微腔结构是通过氢氟酸(HF)腐蚀得到的。实验采用湿法检测,首先将纳米银溶胶基底与罗丹明6g(R6g)混合,找到增强效果最强时的裸光纤微腔结构,在此结构的基础上采用溶胶自组装法制备银纳米颗粒包覆的光纤SERS基底,通过控制自组装时间制备不同光纤SERS基底(Ag/光纤-x,其中x为自组装时间,分别为10,20,30,40,50和60 min)。以10^(-3) mol·L^(-1)的R6g为探针分子,对Ag/光纤-x基底进行初筛,得到增强效果最强的Ag/光纤-30基底。通过检测不同浓度的R6g溶液,对纳米银溶胶基底和Ag/光纤-30基底的SERS性能进行研究。实验结果表明,在相同的实验条件下,纳米银溶胶基底和Ag/光纤-30基底对R6g的检测限(LOD)分别为10^(-6)和10^(-9)mol·L^(-1);在1362 cm^(-1)拉曼位移处对两种基底的拉曼强度和浓度进行对数转换拟合,Ag/光纤-30基底的拟合优度R^(2)达0.9753,远高于纳米银溶胶基底;拉曼信号的再现性检测结果表明,两种基底在各个特征峰处的RSD值均在合理范围内,但Ag/光纤-30基底的RSD值范围更小,范围最大值仅为10.94%;两种基底的稳定性测试结果表明,纳米银溶胶基底35 d后,在1362 cm^(-1)位置处的综合拉曼强度下降了45.90%,而Ag/光纤-30基底35 d后,综合拉曼强度仅下降了17.58%,说明Ag/光纤-30基底具有长期稳定性。同时,对两种基底增强因子(REF)进行计算,对浓度为10^(-6)mol·L^(-1)的R6g溶液,纳米银溶胶基底和Ag/光纤-30基底的REF数值分别为3.49×10^(6)和2.14×10^(7),说明对于同一浓度的R6g溶液,Ag/光纤-30基底具有更强的增强效果,且比纳米银溶胶基底高出一个数量级。通过对比两种基底的SERS性能,表明Ag/光纤-30基底具有更高的灵敏度、更好的再现性以及长期稳定性。因此,基于银纳米颗粒包覆的光纤SERS基底在农残化学分析、生物医学检测等痕量检测方面有潜在的应用价值。

关键词：表面增强拉曼散射纳米银溶胶光纤溶胶自组法罗丹明6g

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耐低钾马铃薯品种的筛选与评价

植物学报 2024年第1期59卷 75-88页

作者：刘寅笃脱军康李成举张锋张春利张莹王云姣范又方姚攀锋孙超刘玉汇刘震毕真真白江平甘肃农业大学农学院/干旱生境作物学国家重点实验室/甘肃省作物遗传改良与种质创新重点实验室兰州730070

土壤缺钾严重降低了我国马铃薯(Solanum tuberosum)的产量。而不同品种马铃薯对低钾的响应差异较大。因此,采用耐低钾马铃薯品种可通过提高钾素利用效率减少钾肥施用量,成为我国农业可持续发展和绿色发展的重要途径。该研究对30个马铃... 详细信息

土壤缺钾严重降低了我国马铃薯(Solanum tuberosum)的产量。而不同品种马铃薯对低钾的响应差异较大。因此,采用耐低钾马铃薯品种可通过提高钾素利用效率减少钾肥施用量,成为我国农业可持续发展和绿色发展的重要途径。该研究对30个马铃薯品种在正常钾处理(202.5 kg·hm^(-2)K_(2)O)和低钾处理(0 kg·hm^(-2)K_(2)O)下的17个指标进行测定,并对9个代表性指标,包括叶面积指数、根冠比、茎叶干质量、根干质量、单株产量、单株大薯产量、单株小薯产量、块茎干质量和块茎钾积累量进行后续分析。结果表明,在低钾条件下,各项指标均有不同程度的下降。主成分分析表明,这9个指标可转换为4个独立的综合指标,累计贡献率达87.1%。根据综合评价值(D值)和聚类分析,将30个品种分为6类,其中第1类为高度耐低钾品种,包括Lucinda、Favorita、Kexin1、Xisen6、Xingjia2、Helan15和Chuanyin2,第2类为中度耐低钾品种,包括Longshu20、Dingshu3、Jizhang12(W)、Jiuen1、Longshu19和Jizhang12(Y)。此外还建立了耐低钾性评价回归模型Y=–0.595+0.247X_(5)+0.155X_(4)+0.138X_3+0.167X_8+0.088X_(1)+0.081X_(6)+0.097X_9+0.053X_(2)(R^(2)=0.999,P=0.000),利用回归方程对30个品种的估计精度均在90%以上。在低钾条件下,可利用单株产量、根干质量、茎叶干质量、块茎干质量、叶面积指数、单株大薯产量、块茎钾积累量和根冠比快速鉴定耐低钾马铃薯品种。

关键词：马铃薯低钾综合评价品种筛选绿色农业