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燃烧机理构建的极小化反应网络方法:C_(2)燃料燃烧

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高等学校化学学报 2024年第1期45卷 94-106页

作者：申屠江涛李宜蔚陆彦戎李娟琴毛业兵李象远四川大学化学工程学院空天动力燃烧与冷却教育部工程研究中心机械工程学院成都610065

针对目前C_(2)燃料反应机理中存在的诸多问题,本文采用极小化反应网络方法,在特定化学分辨率条件下构建了乙烯、乙烷和乙醇等典型C_(2)燃料的燃烧反应机理.构建的C_(2)单组分机理具有简洁的反应网络,采用可逆反应形式,并对反应方向在形... 详细信息

针对目前C_(2)燃料反应机理中存在的诸多问题,本文采用极小化反应网络方法,在特定化学分辨率条件下构建了乙烯、乙烷和乙醇等典型C_(2)燃料的燃烧反应机理.构建的C_(2)单组分机理具有简洁的反应网络,采用可逆反应形式,并对反应方向在形式上进行了统一.在动力学参数方面,采用经典Arrhenius方程(A,Ea)双参数形式,在保证物理意义的同时有利于参数优化.C_(2)机理构建过程中避免了机理简化步骤,能够大幅减少物种数和反应数.动力学模拟结果表明,构建的C_(2)燃烧反应机理在保持较小尺寸的同时有较高的可靠性,并为机理的实际工程应用降低计算成本带来便利.

关键词：燃烧机理极小化反应网络化学分辨率可逆反应 C2燃料

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食管癌围手术期治疗现状和思考

肿瘤 2024年第1期44卷 54-61页

作者：李祥源肖蓉朱美玲上海交通大学医学院附属新华医院肿瘤科上海200092

多年来,中国食管癌围手术期治疗都是以化疗或放化疗为主。近年来,随着以免疫检查点抑制剂为代表的免疫治疗、多学科综合治疗、分子病理指导下的精准治疗以及不同肿瘤负荷表型(T/N负荷相对关系)指导下的导向性选择等不同疗法的涌现,食管... 详细信息

多年来,中国食管癌围手术期治疗都是以化疗或放化疗为主。近年来,随着以免疫检查点抑制剂为代表的免疫治疗、多学科综合治疗、分子病理指导下的精准治疗以及不同肿瘤负荷表型(T/N负荷相对关系)指导下的导向性选择等不同疗法的涌现,食管癌围手术期治疗的传统模式受到了挑战,但这也为重新审视当前食管癌围手术期治疗模式提供了新机遇,并且将有助于促进食管癌围手术期治疗策略的优化。因此,研究者需要对食管癌围手术期治疗的现状充分了解并进行进一步思考。

关键词：食管癌围手术期免疫治疗新辅助放化疗精准治疗

基于机器学习的CH_(4)燃烧动力学机理优化

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高等学校化学学报 2024年第10期45卷 69-77页

作者：曹双双黄济勇李伟张厚君李象远韩优天津大学化工学院天津300072 航天化学能源全国重点实验室湖北航天化学技术研究所襄阳441003 四川大学化学工程学院成都610065

基于径向基函数插值算法构建的机器学习模型,以点火延迟时间(T=1084~2175 K,p=7.3×10^(4)~2.4×10^(6)Pa,φ=0.2~2.0)和层流火焰速度(T=293~600 K,p=5.1×10^(4)~1.1×10^(6)Pa,φ=0.4~2.0)实验数据为优化目标,对CH_(4)燃烧机理的指前因子和活化能进行优化,获得了可在宽工况范围内使用的CH_(4)燃烧机理.与初始的CH_(4)机理(Ori-CH_(4))相比,优化后的CH_(4)机理(Opt-CH_(4))在点火延迟时间上的预测平均误差下降了57.46%,在层流火焰速度上的预测平均误差下降了21.55%.使用Opt-CH_(4)机理对点火延迟时间、层流火焰速度和射流搅拌反应器中的组分浓度变化趋势进行了预测,Opt-CH_(4)机理均表现出优越的预测准确度.在T=1491.5 K,p=1.0×105 Pa,4.988%CH_(4)\19.953%O_(2)\75.059%N_(2)(体积分数)工况下,CH_(3)+O_(2)■CH_(2)O+OH和CH_(2)O+O_(2)■HCO+HO_(2)在各个机理中的敏感性差异是优化前后CH_(4)机理预测准确度不同的主要原因.因此,机器学习方法在燃料燃烧反应动力学机理参数优化上具有广阔的应用前景.

关键词：甲烷燃烧机器学习化学动力学机理优化

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政府补贴对高新技术企业供应链韧性的影响

科技和产业 2024年第16期24卷 139-145页

作者：喻甜李向缘浙江万里学院物流与电子商务学院浙江宁波315100

基于2012—2021年A股上市高新技术企业数据,实证检验了政府补贴对供应链韧性的影响。研究表明,政府补贴显著促进供应链韧性,这一结论在经过稳健性检验和内生性检验之后依然成立;中介机制分析发现,双元创新能力在政府补贴与供应链韧性的... 详细信息

基于2012—2021年A股上市高新技术企业数据,实证检验了政府补贴对供应链韧性的影响。研究表明,政府补贴显著促进供应链韧性,这一结论在经过稳健性检验和内生性检验之后依然成立;中介机制分析发现,双元创新能力在政府补贴与供应链韧性的影响中起到部分中介作用,即政府补贴通过促进企业双元创新能力进而提升其供应链韧性;异质性分析发现,东部地区、非国有企业、小规模的高新技术企业的政府补贴与供应链韧性的影响更显著。实证结果为高新技术企业应对不利冲击提供了管理启示。

关键词：政府补贴高新技术企业供应链韧性双元创新能力

Cracking and buoyancy effect on hydrocarbon endothermic and heat transfer characteristics in rectangular mini-channel

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Chinese Journal of Chemical Engineering 2023年第4期56卷 242-254页

作者： Chengang Yang Huaizhi Han Quan Zhu xiangyuan li School of Chemical Engineering Sichuan UniversityChengdu 610065China Engineering Research Center of Combustion and Cooling for Aerospace Power Ministry of EducationSichuan UniversityChengdu 610065China

Although buoyancy and cracking reactions are strongly coupled in the active cooling process, most of the previous studies consider only one of these factors, and their coupling relationship has not been considerably examined. In this work, this coupling relationship was numerically investigated with complete consideration of different cases of heating, and in the view of energy transport and conversion. By comparing with the no-gravity case(NGC), the results indicate that buoyancy has a significant effect on the bottom-heated case(BHC) and side-heated case(SHC), but has little influence on the top-heated case(THC) owing to the different magnitudes of secondary flow. The heat transfer of the BHC and SHC was significantly enhanced by the secondary flow, but their energy conversion was simultaneously *** conversion of the BHC and SHC was approximately half that of the THC and NGC. For all cases, by analyzing the energy transport ways, the cross section can be classified into three regions in the heating direction. Laminar conduction dominates in region Ⅰ, but gradually fails in region Ⅱ, where its role is replaced by other energy transport ways. In region Ⅲ, convection dominates the energy transport for BHC and SHC, whereas turbulence dominates for THC and NGC.

关键词： Heat transfer Computational fluid dynamics(CFD) Buoyancy Hydrocarbons

Experimental Study of Flow Patterns and Improved Configurations for Pulsating Heat Pipes

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Journal of Thermal Science 2007年第1期16卷 56-62页

作者： Shi liU Jingtao li xiangyuan DONG Huanzhuo CHEN Institute of Engineering Thermophysics Chinese Academy of Sciences EO. Box 2706 Beijing 100080 China

A series of experiments were performed on three types of closed loop pulsating heat pipes （PHPs）, intending to investigate various kinds of flow patterns, and to develop some improved configurations for the PHPs. Optical visualization results indicated that there might exist three flow patterns, i.e. bubble-liquid slug flow, semi-annular flow and annular flow, corresponding to different working conditions. For a given geometry and an adequate fill ratio, the PHPs had the self-adjusting characteristic for the flow patterns （from slug flow to semi-annular and then to annular flow） to meet the demands of the increasing heat input. Two special configurations, one with alternately varying channel diameter, the other equipped with one section of thicker tube, were found to be advantageous in establishing and maintaining reliable circulation of the working fluid. The thermal performance of the PHPs was examined over a range of working conditions. Comparing with the normal PHP with uniform diameter, either of the improved PHPs exhibited higher thermal performance.

关键词： pulsating heat pipe flow patterns improved configurations.

Analysis on First-stage Ignition of n-Heptane at Low Temperatures with a Lumped Skeletal Mechanism

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Chemical Research in Chinese Universities 2022年第6期38卷 1482-1491页

作者： XIAO Jiayu WANG Jingbo WANG Fan li xiangyuan College of Chemical Engineering Sichuan UniversityChengdu610065P.R.China Engineering Research Center of Combustion and Cooling for Aerospace Power Ministry of EducationSichuan UniversityChengdu610065P.R.China Institute of Atomic and Molecular Physics Sichuan UniversityChengdu610065P.R.China

Two-stage ignition exists in the low-temperature combustion process of n-heptane and the first-stage ignition also shows a negative temperature coefficient(NTC) phenomenon. To study key reactions and understand chemical principles affecting the first-stage ignition of n-heptane, a lumped skeletal mechanism with 62 species is obtained based on the detailed NUIGMech1.0 mechanism using the directed relation graph method assisted by sensitivity analysis and isomer lumping. The lumped mechanism shows good performance on ignition delay time under wide conditions. The study revealed that the temperature after the first-stage ignition is higher and a larger amount of fuel is consumed at lower initial temperatures. The temperature at the first-stage ignition is relatively insensitive to the initial temperature. Further sensitivity analysis and reaction path analysis carried out based on the lumped mechanism show that the decomposition of RO_(2) to produce alkene and HO_(2) is the most important reaction to inhibit the first-stage ignitions. The chain branching explosion closely related to the first-stage ignition will be terminated when the rate constant for the RO_(2) decomposition is larger than that of the isomerization of RO_(2) to produce QOOH. The NTC behavior as well as other characteristics of the first-stage ignition can be rationalized from the competition between these two reactions.

关键词： Reduced mechanism Lumping of isomer Low-temperature reaction First-stage ignition Negative temperature coefficient(NTC) phenomenon

High-precision standard enthalpy of formation for polycyclic aromatic hydrocarbons predicting from general connectivity based hierarchy with discrete correction of atomization energy

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Frontiers of Chemical Science and Engineering 2022年第12期16卷 1743-1750页

作者： Zihan Xu Huajie Xu Lu liu Rongpei Jiang Haisheng Ren xiangyuan li School of Chemical Engineering Sichuan UniversityChengdu 610065China Beijing Institute of Aerospace Testing Technology Beijing 100074China Engineering Research Center of Combustion and Cooling for Aerospace Power Ministry of Education Chengdu 610065China

The standard enthalpy of formation is an important predictor of the reaction heat of a chemical *** this work,a high-precision method was developed to calculate accurate standard enthalpies of formation for polycyclic aromatic hydrocarbons based on the general connectivity based hierarchy(CBH)with the discrete correction of atomization *** a comparison with available experimental findings and other high-precision computational results,it was found that the present method can give a good description of enthalpy of formation for polycyclic aromatic *** CBH schemes can broaden the scope of application,this method can be used to investigate the energetic properties of larger polycyclic aromatic hydrocarbons to achieve a high-precision calculation at the CCSD(T)/CBS *** addition,the energetic properties of CBH fragments can be accurately calculated and integrated into a database for future use,which will increase computational *** hope this work can give new insights into the energetic properties of larger systems.

关键词： standard enthalpy of formation polycyclic aromatic hydrocarbons connectivity based hierarchy high-precision calculation

火灾期间GNSS-PWV的变化及与大气颗粒物相关性分析

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北京测绘 2024年第6期38卷 902-906页

作者：邱胜强杨丽平李香园河南省地质局矿产资源勘查中心河南郑州450006 河南方泽地理信息技术有限公司河南郑州450006 河南省第五地质勘查院有限公司河南郑州450001

本研究以2020年美国加州森林火灾为具体案例,利用火灾影响区域内5个全球卫星导航系统(GNSS)站点约1年时长的数据集,全面分析了火灾不同阶段下可降水汽含量(PWV)的动态变化及其与大气颗粒物(PM)浓度的相关性。首先,研究证实了北、东、垂... 详细信息

本研究以2020年美国加州森林火灾为具体案例,利用火灾影响区域内5个全球卫星导航系统(GNSS)站点约1年时长的数据集,全面分析了火灾不同阶段下可降水汽含量(PWV)的动态变化及其与大气颗粒物(PM)浓度的相关性。首先,研究证实了北、东、垂向3个方向上的坐标解算精度均在毫米级,且GNSS_PWV的解算精度在2 mm左右。其次,大气颗粒物浓度在火灾发生前维持在较低水平,并呈示出稳定的变化模式。火灾发生时期,PM浓度逐渐增加,在约第250天达到峰值,随后逐渐下降。相应地,GNSS_PWV数值也呈现出与PM浓度高度一致的变化模式。最后,通过统计分析,发现火灾前、中、后期,5个GNSS站点处GNSS_PWV与SUM_PM之间的平均相关性分别为26.01%、45.03%和27.61%,并且所有阶段的相关性P值均小于0.05,GNSS_PWV与PM浓度之间存在显著的相关性。

关键词：全球卫星导航系统可降水汽含量火灾大气颗粒物(PM) 相关性