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A Fractional-Order Study for Bicomplex Haemorrhagic Infection in Several Populations Conditions
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作者 Muhammad Farman Muhammad Hashir Zubair +2 位作者 Hua Li Kottakkaran Sooppy Nisar Mohamad Hafez 《Computer Modeling in Engineering & Sciences》 2026年第1期926-953,共28页
Lassa Fever(LF)is a viral hemorrhagic illness transmitted via rodents and is endemic in West Africa,causing thousands of deaths annually.This study develops a dynamic model of Lassa virus transmission,capturing the pr... Lassa Fever(LF)is a viral hemorrhagic illness transmitted via rodents and is endemic in West Africa,causing thousands of deaths annually.This study develops a dynamic model of Lassa virus transmission,capturing the progression of the disease through susceptible,exposed,infected,and recovered populations.The focus is on simulating this model using the fractional Caputo derivative,allowing both qualitative and quantitative analyses of boundedness,positivity,and solution uniqueness.Fixed-point theory and Lipschitz conditions are employed to confirm the existence and uniqueness of solutions,while Lyapunov functions establish the global stability of both disease-free and endemic equilibria.The study further examines the role of the Caputo operator by solving the generalized power-law kernel via a two-step Lagrange polynomial method.This approach offers practical advantages in handling additional data points in integral forms,though Newton polynomial-based schemes are generally more accurate and can outperform Lagrange-based Adams-Bashforth methods.Graphical simulations validate the proposed numerical approach for different fractional orders(ν)and illustrate the influence of model parameters on disease dynamics.Results indicate that increasing the fractional order accelerates the decline of Lassa fever in both human and rodent populations.Moreover,fractional-order modeling provides more nuanced insights than traditional integer-order models,suggesting potential improvements for medical intervention strategies.The study demonstrates that carefully chosen fractional orders can optimize convergence and enhance the predictive capacity of Lassa fever models,offering a promising direction for future research in epidemiological modeling. 展开更多
关键词 Lassa fever mathematical model caputo fractional operator lyapunov stability
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CT-derived fractional flow reserve combined with atherosclerotic extent to determine long-term outcomes in diabetic patients with coronary artery disease
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作者 Zhi-Qiang WANG Zhen-Nan LI +1 位作者 Zhi-Hui HOU Bin LU 《Journal of Geriatric Cardiology》 2026年第1期27-35,共9页
Background There is still limited data on predictive value of coronary computed tomography angiography(CCTA)–derived fractional flow reserve(CT-FFR) for long term outcomes. We examined the long-term prognostic value ... Background There is still limited data on predictive value of coronary computed tomography angiography(CCTA)–derived fractional flow reserve(CT-FFR) for long term outcomes. We examined the long-term prognostic value of CT-FFR combined with CCTA–defined atherosclerotic extent in diabetic patients with coronary artery disease(CAD).Methods A retrospective pooled analysis of individual patient data was performed. Deep-learning-based vessel-specific CTFFR was calculated. All patients enrolled were followed-up for at least 5 years. Predictive abilities for major adverse cardiac events(MACE) were compared among three models(model 1), constructed using clinical variables;model 2, model 1+CCTA–derived atherosclerotic extent(Leiden risk score);and model 3, model 2+CT-FFR.Results A total of 480 diabetic patients [median age, 61(55–66) years;52.9% men] were included. During a median follow-up time of 2197(2126–2355) days, 55 patients(11.5%) experienced MACE. In multivariate-adjusted Cox models, Leiden risk score(HR: 1.06;95% CI: 1.01–1.11;P = 0.013) and CT-FFR ≤ 0.80(HR: 6.54;95% CI: 3.18–13.45;P < 0.001) were the independent predictors. The discriminant ability was higher in model 2 than in model 1(C-index, 0.75 vs. 0.63;P < 0.001) and was further promoted by adding CT-FFR to model 3(C-index, 0.81 vs. 0.75;P = 0.002). Net reclassification improvement(NRI) was 0.19(P = 0.009) for model 2 beyond model 1. Of note, adding CT-FFR to model 3 also exhibited significantly improved reclassification compared with model 2(NRI = 0.14;P = 0.011).Conclusion In diabetic patients with CAD, CT-FFR provides robust and incremental prognostic information for predicting longterm outcomes. The combined model exhibits improved prediction abilities, which is beneficial for risk stratification. 展开更多
关键词 fractional flow reserve ct ffr coronary artery disease cad methods tomography angiography ccta derived coronary artery disease atherosclerotic extent fractional flow reserve diabetic patients coronary computed tomography angiography
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Molecular composition of water soluble fraction of petroleum products and crude oils:Insights into groundwater contamination potential and environmental forensics
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作者 Wang Yu Yuruo Wan +3 位作者 Wei Zhou Jiayi An Liting Tian Jie Ma 《Journal of Environmental Sciences》 2026年第1期437-444,共8页
Petroleum leakage is a major groundwater contamination source,with chemical composition of water soluble fractions(WSFs)from diverse oil sources significantly impacting groundwater quality and source identification.Th... Petroleum leakage is a major groundwater contamination source,with chemical composition of water soluble fractions(WSFs)from diverse oil sources significantly impacting groundwater quality and source identification.The aim of this study was to assess impact of 15 diverse oils on groundwater quality and environmental forensics based on oil-water equilibrium experiments.Our results indicate that contamination of groundwater by gasoline and naphtha is primarily attributed to volatile hydrocarbons,while pollution from diesel,kerosene,and crude oil is predominantly from non-hydrocarbons.Rapid determination of the extent of non-hydrocarbon pollution in WSFs was achieved through a new quantitative index.Gasoline and naphtha exhibited the highest groundwater contamination potential while kerosene and light crude oils were also likely to cause groundwater contamina-tion.Although volatile hydrocarbons in the WSFs of diesel and jet fuel do not easily exceed current regulatory standards,unregulated non-hydrocarbons may pose a more severe contamination risk to groundwater.Notably,the presence of significant benzene and toluene,hydrogenation and alkylation products(e.g.,C4-C5 alkylben-zenes,alkylindenes,alkyltetralins,and dihydro-indenes),cycloalkanes in WSFs can effectively be utilized for preliminary source identification of light distillates,middle distillates,and crude oils,respectively. 展开更多
关键词 Petroleum hydrocarbons Water soluble fraction Contaminated sites Groundwater contamination Source identification
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Land use type shapes carbon pathways in Tibetan alpine ecosystems:Characterization of ^(13)C abundance in aggregates and density fractions
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作者 Xin Wan Dangjun Wang +7 位作者 Junya Li Shuaiwen Zhang Linyang Li Minghui He Zhiguo Li Hao Jiang Peng Chen Yi Liu 《Journal of Integrative Agriculture》 2026年第2期448-459,共12页
Insight into the carbon turnover in soil aggregates and density fractions is essential for reducing the uncertainty in estimating carbon pools on the Tibetan Plateau,and how they vary with land use type is unclear.In ... Insight into the carbon turnover in soil aggregates and density fractions is essential for reducing the uncertainty in estimating carbon pools on the Tibetan Plateau,and how they vary with land use type is unclear.In this study,the effect of land use type on carbon storage and fractionation was quantified based on organic carbon and its ^(13)C abundance at the microscale of soil aggregates and density fractions in Tibetan alpine ecosystems.The sequence of soil aggregate destruction in the land use types of plantation(13.1%)<shrubland(32.7%)<grassland(47.9%)<farmland(61.8%)shows that plantations strengthen the soil structure.Plantation land had a greater contribution of light fraction organic carbon(28.3%)but a lower contribution of mineral-associated organic carbon(40.6%)to the carbon stock compared to farmland(13.5 and 70.3%).Interestingly,plantation land enhanced the aggregational differentiation of organic carbon and ^(13)C in each density fraction,whereas no such phenomenon existed in the soil organic carbon.Carbon isotope analyses revealed that carbon transfer in the plantation land occurred from the light fraction in macroaggregates(–24.9‰)to the mineral-associated fraction in microaggregates(–19.9‰).When compared to the other three land use types,the low transferability of carbon in aggregates and density fractions in plantation land provides a stable carbon pool for the Tibetan Plateau.This study shows that plantations can mitigate global climate change by slowing carbon transfer and increasing carbon storage at the microscale of aggregates and density fractions in alpine regions. 展开更多
关键词 land use type soil aggregate density fractions carbon transfer Tibetan Plateau
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The Immunomodulatory,Anti-Tumor,and Metabolic Regulatory Effects of Fraction D of Polysaccharide from Grifola frondosa:Clinical Experiments and Mechanistic Insights
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作者 Nurfarih Hanna Mohd Zarif Fikri Bin Mohd +1 位作者 Muhammad Nabil Fikri Bin Mohd Nurfarazuna Binti Mohd Fadrol 《Proceedings of Anticancer Research》 2026年第1期84-93,共10页
Grifola frondosa(Maitake)is traditionally valued for its health benefits,with polysaccharides being key bioactive components.This paper investigates a specific subfraction,Fraction D(GFP-D),evaluating its clinical eff... Grifola frondosa(Maitake)is traditionally valued for its health benefits,with polysaccharides being key bioactive components.This paper investigates a specific subfraction,Fraction D(GFP-D),evaluating its clinical effects and mechanisms in immune enhancement,adjunctive anti-tumor activity,and regulation of glucose/lipid metabolism.Three clinical trials were conducted.In an immune study,120 healthy volunteers(CD4+T cell count 500–1000 cells/μL)received 150 mg/day GFP-D for 8 weeks,resulting in significant increases in CD4+T cells(from 632±95 to 812±108 cells/μL,28.5%increase,within the physiological activation range),CD4+/CD8+ratio,NK cell activity,IL-2,and IFN-γ(all P<0.001 vs.placebo).An anti-tumor study with 80 advanced cancer patients(stratified by age,tumor stage,and histotype)showed that adding 1000 mg/day GFP-D to chemotherapy improved objective response rate(52.5%vs.30.0%,P=0.036,95%CI:1.02–3.87),one-year progression-free survival(55.8%vs.33.3%,P=0.022),and preserved immune parameters versus chemotherapy alone.A metabolic study in 90 type 2 diabetes patients found that 400 mg/day GFP-D for 12 weeks significantly lowered fasting glucose,HbA1c,total cholesterol,triglycerides,and LDL-C,while raising HDL-C(from 1.0±0.2 to 1.2±0.2 mmol/L,20%increase,supported by increased AMPK phosphorylation).Mechanistically,immune enhancement involves macrophage/dendritic cell activation via Dectin-1/TLR4 receptors(confirmed by increased receptor expression and downstream signaling molecules),promoting cytokine-driven T/NK cell responses.Anti-tumor effects stem from immunomodulation,direct induction of cancer cell apoptosis(via mitochondrial/caspase pathways,verified by increased Bax/Bcl-2 ratio and caspase-3 activation),and angiogenesis inhibition by downregulating VEGF.Metabolic benefits are linked to AMPK pathway activation in liver/muscle(confirmed by increased p-AMPK/AMPK ratio),enhancing glucose uptake and inhibiting gluconeogenesis/lipogenesis,alongside modulation of gut microbiota(increased Bifidobacterium and Lactobacillus abundance).All trials reported no severe adverse events related to GFP-D;liver/kidney function parameters(ALT,AST,creatinine,urea nitrogen)remained within normal ranges throughout the intervention.Collectively,GFP-D emerges as a multi-functional bioactive agent with substantial therapeutic potential. 展开更多
关键词 Grifola frondosa Maitake polysaccharide fraction D Immune modulation Adjunctive cancer therapy Glycemic control Lipid metabolism Clinical trial Mechanism of action
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基于VOF-DPM的不同供油压力下扩口式离心喷嘴雾化特性研究
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作者 霍尧 王博涵 《机械管理开发》 2026年第1期9-15,共7页
为揭示供油压力对扩口式离心喷嘴雾化特性的影响规律与内在机理,采用VOF-DPM耦合模型,对喷嘴在0.2~2.0 MPa不同供油压力下的内部流场、出口液膜厚度、雾化锥角及索太尔平均直径(SMD)进行了系统性的数值模拟研究。结果表明:喷嘴内部空气... 为揭示供油压力对扩口式离心喷嘴雾化特性的影响规律与内在机理,采用VOF-DPM耦合模型,对喷嘴在0.2~2.0 MPa不同供油压力下的内部流场、出口液膜厚度、雾化锥角及索太尔平均直径(SMD)进行了系统性的数值模拟研究。结果表明:喷嘴内部空气芯的稳定性是决定雾化形态的关键;供油压力的升高同时增强了燃油的轴向动量与内部离心效应。更强的离心作用使得出口液膜厚度随压力升高而单调减小,从142μm降至114μm,然而由于燃油轴向动量的增幅更为显著,导致喷雾机理从离心主导向轴向主导转变。受此影响,雾化锥角随压力升高而单调减小,从约65°降至55°。更薄的液膜有利于破碎,因此SMD随压力升高而减小,雾化质量得到改善。研究揭示了供油压力对喷嘴雾化特性的调控机制,为喷嘴设计优化与燃烧系统调控提供了理论依据。 展开更多
关键词 扩口式离心喷嘴 vof-DPM模型 雾化特性 供油压力 索太尔平均直径 空气芯
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A_(α)-Spectral Conditions for(a,b,k)-Factor-Critical Graphs and Fractional ID-[a,b]-Factor-Critical Covered Graphs
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作者 Yonglei CHEN Fei WEN 《Journal of Mathematical Research with Applications》 2026年第1期1-12,共12页
In this paper,we first give a sufficient condition for a graph being fractional ID-[a,b]-factor-critical covered in terms of its independence number and minimum degree,which partially answers the problem posed by Sizh... In this paper,we first give a sufficient condition for a graph being fractional ID-[a,b]-factor-critical covered in terms of its independence number and minimum degree,which partially answers the problem posed by Sizhong Zhou,Hongxia Liu and Yang Xu(2022).Then,an A_(α)-spectral condition is given to ensure that G is a fractional ID-[a,b]-factor-critical covered graph and an(a,b,k)-factor-critical graph,respectively.In fact,(a,b,k)-factor-critical graph is a graph which has an[a,b]-factor for k=0.Thus,these above results extend the results of Jia Wei and Shenggui Zhang(2023)and Ao Fan,Ruifang Liu and Guoyan Ao(2023)in some sense. 展开更多
关键词 A_(α)-spectral radius (a b k)-factor fractional(g f)-factor ID-factor-critical graph independence number
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基于DES模型及VOF方法的泄洪消能结构水流脉动特性分析 被引量:1
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作者 侯春尧 张洪毅 +5 位作者 胡长浩 刘璐瑶 刘康 谢辉 李永龙 王皓冉 《科学技术与工程》 北大核心 2025年第18期7770-7777,共8页
强烈的水流脉动是造成消力池等水工结构损伤的重要原因之一,因此明晰水工结构中的水流脉动特性对保障工程安全运行至关重要。基于DES模型及VOF方法建立了亭子口水电站消力池水工模型的精细数值模型,模拟结果与实验结果一致性较好。基于... 强烈的水流脉动是造成消力池等水工结构损伤的重要原因之一,因此明晰水工结构中的水流脉动特性对保障工程安全运行至关重要。基于DES模型及VOF方法建立了亭子口水电站消力池水工模型的精细数值模型,模拟结果与实验结果一致性较好。基于数值模拟结果分析了消力池中压力波动、脉动流速、涡量、以及紊动能的分布变化情况。结果表明消力池中压力波动沿水流方向表现出双峰分布特点,且在水流冲击区脉动量占比超过10%;展向和流向脉动流速在消力池中占主导地位,垂向脉动较弱,在水舌碰撞区域底板中心线处的展向脉动流速迅速减小;底板中心线和表孔中心线上流向和垂向的涡量具有小时均值、大脉动值的特点,跌坎引起的横轴旋涡对展向涡量分布有较大影响。紊动能能谱分析的结果显示消力池中水流脉动主要由大量1Hz以下的低频脉动组成,表明消力池中的紊流波动主要由大尺度和低频的涡流控制。研究结果有助于加深对消力池等泄洪消能结构水流特性的认知,为其设计及安全评估提供了一定参考。 展开更多
关键词 消力池 数值模拟 脉动特性 DES模型 vof方法
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基于VOF模型的真空引水罐内流动特性 被引量:1
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作者 王欢 赵睿杰 +2 位作者 李红 杨帆 潘绪伟 《排灌机械工程学报》 北大核心 2025年第1期74-79,共6页
为解决真空引水罐出口气体流出问题,探究罐内气液两相流动机理,基于RNG k-ε湍流模型和VOF模型对真空引水罐进行计算,对不同初始状态下真空引水罐内的气液两相交界面形态、出口管气体流出量以及出口管内流动状态进行分析,讨论了真空引... 为解决真空引水罐出口气体流出问题,探究罐内气液两相流动机理,基于RNG k-ε湍流模型和VOF模型对真空引水罐进行计算,对不同初始状态下真空引水罐内的气液两相交界面形态、出口管气体流出量以及出口管内流动状态进行分析,讨论了真空引水罐内初始状态对罐内流场的影响,总结了罐内水位对内部流场及出口管的作用关系.结果显示:当初始水位远高于进水管时会大幅优化真空引水罐内流场;与原初始水位相比,罐内气液两相交界面的交互作用减少;气体流出量体积分数峰值从最初的6.916%降至0.106%,平均值从3.442%降至0.027%;出口管流态得到明显改善,顶部低压区域减少.研究结果表明初始水位的变化会影响真空引水罐内流场特性、气体流出量及出口管流态,为深入认识真空引水罐内部流动及真空引水罐的设计提供了数据支撑. 展开更多
关键词 引水罐 流体体积模型 罐内水位 罐内流场 出口流态
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基于VOF方法的码头群桩结构流固耦合动力响应数值模拟 被引量:1
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作者 张其一 孟祥飞 +1 位作者 陈凯 郭东起 《水运工程》 2025年第2期178-183,231,共7页
高桩结构是一种港口海岸码头广泛应用的结构形式,其在波浪作用下的结构动力响应是保证码头稳定运行的关键因素。使用ABAQUS软件建立码头三维模型、STAR-CCM+软件建立波浪水槽,采用k-ε湍流模型和流体体积(VOF)运动界面追踪方法模拟波浪... 高桩结构是一种港口海岸码头广泛应用的结构形式,其在波浪作用下的结构动力响应是保证码头稳定运行的关键因素。使用ABAQUS软件建立码头三维模型、STAR-CCM+软件建立波浪水槽,采用k-ε湍流模型和流体体积(VOF)运动界面追踪方法模拟波浪,实现码头群桩结构和波浪之间双向耦合的模拟。由于桩距与桩直径的比值大于4,不需要考虑桩间相互影响,对比模型试验误差低于5%精度可以满足要求。结果表明,码头群桩在波高为0.3、0.4、0.5 m下的最大受力和位移均能满足规范要求,桩顶处位移最大为0.66 mm;最大应力产生在群桩前排桩底,为152.4 kPa,桩底区域混凝土易发生失稳破坏,实际工程中应格外关注。 展开更多
关键词 群桩结构 vof方法 双向耦合 结构动力响应
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基于DPM-VOF耦合的高铅渣底吹还原炉内多相流动数值模拟 被引量:1
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作者 闫红杰 黄正宗 +2 位作者 郝澳 夏韬 刘柳 《中国有色金属学报》 北大核心 2025年第2期607-620,共14页
高铅渣底吹还原炉内天然气-熔体或载气-熔体-煤粉构成的多相体系复杂行为与熔炼效率和系统产能紧密相关。本文基于DPM-VOF耦合模型,研究了工业尺度的高铅渣底吹还原炉内分别以天然气和煤粉为还原剂的气-液两相流和气-液-固多相流复杂行... 高铅渣底吹还原炉内天然气-熔体或载气-熔体-煤粉构成的多相体系复杂行为与熔炼效率和系统产能紧密相关。本文基于DPM-VOF耦合模型,研究了工业尺度的高铅渣底吹还原炉内分别以天然气和煤粉为还原剂的气-液两相流和气-液-固多相流复杂行为。结果表明:天然气作还原剂时,炉膛两端熔体流速平缓,喷枪区域流速剧烈,呈“脉冲状”分布;喷枪附近压力呈两侧大、中间小的“V”字形分布;喷枪区域压力波动剧烈,虽可强化气液搅拌过程但易造成喷枪损坏和熔体喷溅。采用煤粉作还原剂时,煤粉从喷枪喷出后最初分布在气团内部和气液交界面处,随后扩散至熔池中上部和烟气区域;熔池内煤粉分布在0.25~0.85 m深度范围;喷枪附近煤粉浓度相近,均未出现沉积现象。 展开更多
关键词 底吹还原炉 多相流 DPM-vof模型 数值模拟 直接炼铅工艺
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基于VOF-FEM方法考虑内部构件影响的大型液舱晃荡强度研究
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作者 李昊 刘俊 +2 位作者 毛佳寅 黄德海 郭涵慧 《中国造船》 北大核心 2025年第4期148-159,共12页
基于VOF方法,针对某船大型液舱建立了考虑内部构件影响的三维晃荡数值模型,开展水动力载荷计算,与液舱晃荡试验的对比验证了计算方法的有效性。基于PATRAN平台的PCL语言编写工具软件,将时空变化的冲击载荷自动加载到有限元模型,开展了... 基于VOF方法,针对某船大型液舱建立了考虑内部构件影响的三维晃荡数值模型,开展水动力载荷计算,与液舱晃荡试验的对比验证了计算方法的有效性。基于PATRAN平台的PCL语言编写工具软件,将时空变化的冲击载荷自动加载到有限元模型,开展了在不同装载高度和船舶不同运动状态下液舱结构动力响应分析和强度校核。对晃荡载荷的准静态等效方法展开研究,采用载荷时历最大值及载荷包络值两种等效方法进行对比分析。结果表明:在目标船设计工况下,载荷包络值的静力分析应力略大于其他状态下的应力,且比值在1.000~1.064浮动,涵盖了所有危险状态,建议用该方法获得的准静态载荷进行液舱晃荡强度校核。 展开更多
关键词 液舱晃荡 vof-FEM载荷转换 瞬态响应分析 静力分析 强度校核
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基于VOF方法的同轴气泡聚并数值模拟研究 被引量:1
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作者 郝文杰 韩晋玉 +2 位作者 刘瑶 赵陈儒 薄涵亮 《原子能科学技术》 北大核心 2025年第6期1262-1271,共10页
气液两相流动广泛存在于反应堆堆芯以及蒸汽发生器等设备中。气泡聚并、破碎等气泡动力学行为直接影响相关设备的热工水力性能。群平衡模型(PBM)是多相流系统中处理多组分粒子平衡问题的重要方法。气泡聚并核函数是PBM主要核函数之一,... 气液两相流动广泛存在于反应堆堆芯以及蒸汽发生器等设备中。气泡聚并、破碎等气泡动力学行为直接影响相关设备的热工水力性能。群平衡模型(PBM)是多相流系统中处理多组分粒子平衡问题的重要方法。气泡聚并核函数是PBM主要核函数之一,用于描述两个或多个气泡在碰撞过程中聚并为一个较大气泡的概率,其准确性直接影响欧拉-欧拉框架下的气泡动力学行为研究及热工水力性能的预测。排液模型是当前应用最为广泛的聚并效率模型,是聚并核函数的重要部分。通过将流体体积法(VOF)与连续表面力模型(CSF)相结合对两同轴气泡聚并过程开展了2D数值模拟,并根据模拟结果定量获得气泡聚并过程的排液时间,通过研究不同黏度下气泡的聚并,定量描述了气泡开始排液的接触时刻,讨论了初始液膜厚度与气泡直径、形变比以及黏度之间的关系,对文献中已有的4个排液时间模型的适用性及准确性进行系统评价。研究结果表明,接触时刻的定义,初始液膜厚度的预测,以及黏性力和惯性力作用的综合考虑和评估对于提高排液时间模型的准确性,扩展其适用范围,进而提高PBM方法的计算准确性有重要的意义。 展开更多
关键词 vof方法 气泡聚并 接触时刻 初始液膜厚度 排液时间
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基于VOF方法的多级交替注入酸化压裂指进模拟
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作者 高步栋 牟建业 +3 位作者 张士诚 马新仿 卢盼盼 王雷 《石油科学通报》 2025年第3期540-552,共13页
致密碳酸盐岩储层常采用多级交替注入酸压技术来增加裂缝面差异刻蚀和提高酸蚀裂缝导流能力。通过数值模拟可优化多级交替注入施工参数,从而提高酸压改造效果,对压后增产及稳产具有重要作用。但目前关于多级交替注入酸压的数值模拟常忽... 致密碳酸盐岩储层常采用多级交替注入酸压技术来增加裂缝面差异刻蚀和提高酸蚀裂缝导流能力。通过数值模拟可优化多级交替注入施工参数,从而提高酸压改造效果,对压后增产及稳产具有重要作用。但目前关于多级交替注入酸压的数值模拟常忽略酸岩反应或采用等效粘度方法开展研究,模拟结果与实际情况仍存在较大偏差。针对该问题,本文基于流体体积法(VOF)建立了考虑流体界面追踪和酸岩反应的多级交替注入酸压数学模型。采用有限差分法对数学模型进行离散,得到数值模型,并通过编程求解。通过将本模型模拟结果与实验结果以及解析解进行对比,验证了模型在模拟粘性指进及酸液刻蚀方面的准确性。在此基础上,利用该模型开展了多级交替注入酸压模拟,分析了不同交替注入级数下的酸液流动反应规律、粘性指进特征及刻蚀缝宽变化规律。同时,综合考虑酸液作用距离、指进数量及其覆盖面积,提出粘性指进系数,评价了多级交替注入酸压的差异刻蚀效果。研究结果表明,在典型缝宽及交替注入条件下,低粘酸液在粘度差作用下在裂缝中逐渐形成优势通道,即指进现象。随着注入级数增加,相邻的指进分支之间竞争发育,指进合并。酸液有效作用距离随着交替注入级数增加而增加。存在某一临界注入级数,当注入级数大于该级数后,酸液作用距离增加速度变缓。此时,增加级数只能使指进区域内刻蚀增加。因此,对于给定的裂缝条件和酸液体系,存在一个较优的注入级数范围,使得裂缝差异刻蚀和酸液作用距离同时达到较佳效果。本文模型可为多级交替注入酸压提供优化模拟工具,模拟结果可为现场施工方案设计提供理论依据。 展开更多
关键词 多级交替注入 酸压 vof 界面追踪 粘性指进 酸液作用距离 数值模拟
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基于VOF方法的半封闭圆柱入水受载和运动特征 被引量:1
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作者 文华东 汪子钊 《船舶工程》 北大核心 2025年第3期145-151,共7页
[目的]与传统的实心圆柱形入水过程相比,开放空腔圆柱形结构的入水过程更为复杂,对其入水机理的研究对类似结构的设计具有重要指导意义。[方法]采用流体体积法(VOF)对开放空腔圆柱的入水机理进行研究,对其在入水过程中的载荷和运动特征... [目的]与传统的实心圆柱形入水过程相比,开放空腔圆柱形结构的入水过程更为复杂,对其入水机理的研究对类似结构的设计具有重要指导意义。[方法]采用流体体积法(VOF)对开放空腔圆柱的入水机理进行研究,对其在入水过程中的载荷和运动特征进行分析。基于计算流体力学(CFD)方法,以现有试验数据为基准,进行网格不确定性分析,验证该数值方法的准确性。在此基础上,研究不同入水角度下半封闭圆柱的入水过程,评估入水角度对半封闭圆柱所受载荷和运动特征的影响。[结果]研究结果表明:减小入水角度能有效降低圆柱表面的接触载荷;在半封闭圆柱入水过程中,圆柱两侧不对称的气泡空腔会导致横向速度出现短暂波动,波动幅值随入水角度的增大而减小,同时圆柱内部空气压力发生波动会导致圆柱的横向速度和竖向速度出现周期性波动,该波动受入水角度的影响较小,在各入水角下均较为明显。[结论]该研究可供类似结构的声呐浮标和某些水下机器人的结构设计参考。 展开更多
关键词 半封闭圆柱入水 流体体积法(vof) 空腔演化 流体载荷
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Atmospheric reductive catalytic fractionation of lignocellulose integrated with one-pot catalytic conversion of carbohydrate yielding valuable lignin monomers and platform chemicals from corn straw 被引量:2
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作者 Meng-Ying Liu Zhe-Hui Zhang +7 位作者 Xue-Qi Wang Qian Sun Chen Zhang Yu Li Zhuohua Sun Katalin Barta Feng Peng Tong-Qi Yuan 《Green Energy & Environment》 SCIE EI CAS 2025年第1期161-172,共12页
Developing a cost-effective and environmentally friendly process for the production of valuable chemicals from abundant herbal biomass receives great attentions in recent years.Herein,taking advantage of the“lignin f... Developing a cost-effective and environmentally friendly process for the production of valuable chemicals from abundant herbal biomass receives great attentions in recent years.Herein,taking advantage of the“lignin first”strategy,corn straw is converted to valuable chemicals including lignin monomers,furfural and 5-methoxymethylfurfural via a two steps process.The key of this research lies in the development of a green and low-cost catalytic process utilizing magnetic Raney Ni catalyst and high boiling point ethylene glycol.The utilization of neat ethylene glycol as the sole slovent under atmospheric conditions obviates the need for additional additives,thereby facilitating the entire process to be conducted in glass flasks and rendering it highly convenient for scaling up.In the initial step,depolymerization of corn straw lignin resulted in a monomer yield of 18.1 wt%.Subsequently,in a dimethyl carbonate system,the carbohydrate component underwent complete conversion in a one-pot process,yielding furfural and 5-methoxymethylfurfural as the primary products with an impressive yield of 47.7%. 展开更多
关键词 Atmospheric reductive catalytic fractionation Corn straw Ethylene glycol Raney Ni 5-Methoxymethylfurfural
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基于DPM-to-VOF方法的液滴射流撞壁过程研究
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作者 陈青山 王明军 +2 位作者 田文喜 秋穗正 苏光辉 《核动力工程》 北大核心 2025年第1期83-91,共9页
喷淋雾化被广泛应用于核动力设备中,以保证其安全稳定运行。喷淋时,部分液滴会撞击设备壁面,以液膜的形式进行扩展和演变。基于Fluent软件的离散相-连续相转换(DPM-to-VOF,DTV)方法进行了液滴射流撞壁研究,使用两液滴滴落过程试验图像... 喷淋雾化被广泛应用于核动力设备中,以保证其安全稳定运行。喷淋时,部分液滴会撞击设备壁面,以液膜的形式进行扩展和演变。基于Fluent软件的离散相-连续相转换(DPM-to-VOF,DTV)方法进行了液滴射流撞壁研究,使用两液滴滴落过程试验图像验证了模拟方法的准确性,研究了液滴射流注入速度、入射角度对壁面液膜形态的影响规律,得到了液滴溅射率随入射条件的变化情况,并分析了液滴撞击壁面时重力、表面张力、速度分量等对液膜形态扩展过程、液滴溅射率的影响。研究发现,增大注入速度能加大对液膜的扰动,液膜与壁面的接触面积显著增大,液膜区宽度和高度增加;增大入射角度对液膜形态的改变影响较大,体现在液膜区宽度增加和液膜区高度减小,液膜表面稳定性减低。溅射率随着注入速度和入射角度的增大而增大,其中,入射角度对溅射率的影响更大。 展开更多
关键词 离散相-连续相转换 液滴射流撞壁 液膜扩展演变 液滴滴落融合
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基于VOF-to-DPM的旋流喷嘴结构优化与雾化过程分析
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作者 凌航涛 任婧杰 +4 位作者 鲍雨露 毕明树 钟伦超 王志甄 许文彩 《化学工程》 北大核心 2025年第12期64-70,共7页
为改善雾化喷嘴对水基类消毒剂的分散效果,采用VOF(流体体积函数法)-to-DPM(离散相模型)模型对某型压力旋流喷嘴雾化过程建立数值模型,并通过实验验证模型的准确性。在实验验证的基础上使用正交试验方法,以增大雾化锥角和减小索特平均直... 为改善雾化喷嘴对水基类消毒剂的分散效果,采用VOF(流体体积函数法)-to-DPM(离散相模型)模型对某型压力旋流喷嘴雾化过程建立数值模型,并通过实验验证模型的准确性。在实验验证的基础上使用正交试验方法,以增大雾化锥角和减小索特平均直径D_(32)为优化目标,对旋流喷嘴的出口直径、旋流槽个数、旋流槽螺旋角、旋流槽深度这4个关键结构参数进行组合优化。研究结果表明:4个结构参数中,对雾化锥角和D_(32)影响最大的因素均为出口直径。优化后的喷嘴与原喷嘴相比,雾化锥角增大了15.5%,D_(32)减小了27.6%。除此之外,文中所述数值模型可实现对液膜破碎阶段的细节捕捉和揭示液滴形成机理,可为旋流喷嘴的设计与性能优化提供参考。 展开更多
关键词 旋流喷嘴 vof-to-DPM 正交试验 雾化锥角 索特平均直径
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Impact of pitch fraction oxidation on the structure and sodium storage properties of derived carbon materials 被引量:1
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作者 QI Su-xia YANG Tao +6 位作者 SONG Yan ZHAO Ning LIU Jun-qing TIAN Xiao-dong WU Jin-ru LI Hui LIU Zhan-jun 《新型炭材料(中英文)》 北大核心 2025年第2期421-439,共19页
Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation ac... Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation activity were studied.Several different carbon materi-als were produced from them by oxida-tion in air(350℃,300 mL/min)fol-lowed by carbonization(1000℃ in Ar),and the effect of the cross-linked structure on their structure and sodium storage properties was investigated.The results showed that the two pitch fractions were obviously different after the air oxidation.The TS fraction with a low degree of condensation and abundant side chains had a stronger oxidation activity and thus introduced more cross-linked oxygen-containing functional groups C(O)―O which prevented carbon layer rearrangement during the carbonization.As a result,a disordered hard carbon with more defects was formed,which improved the electrochemical performance.Therefore,the carbon materials derived from TS(O-TS-1000)had an obvious disordered structure and a larger layer spacing,giving them better sodium storage perform-ance than those derived from the TI-PS fraction(O-TI-PS-1000).The specific capacity of O-TS-1000 was about 250 mAh/g at 20 mA/g,which was 1.67 times higher than that of O-TI-PS-1000(150 mAh/g). 展开更多
关键词 Pitch fractions Air oxidation Derived carbon materials Na^(+)storage
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Local Rate of Convergence in the Functional Limit Theorem for Increments of a Fractional Brownian Motion 被引量:1
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作者 LIU Yonghong DING Ding ZHOU Xia 《数学进展》 北大核心 2025年第1期197-211,共15页
In this paper,we present local functional law of the iterated logarithm for Cs?rg?-Révész type increments of fractional Brownian motion.The results obtained extend works of Gantert[Ann.Probab.,1993,21(2):104... In this paper,we present local functional law of the iterated logarithm for Cs?rg?-Révész type increments of fractional Brownian motion.The results obtained extend works of Gantert[Ann.Probab.,1993,21(2):1045-1049]and Monrad and Rootzén[Probab.Theory Related Fields,1995,101(2):173-192]. 展开更多
关键词 fractional Brownian motion INCREMENT local functional law of the iterated logarithm large deviation small deviation
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