B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.T...B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.The pathways of tar compound radical absorbed by CaO were determined firstly through comparing enthalpy changes of the absorption,and then Mulliken population changes were analyzed.The results show that the absorption of tar model compound radical and CaO is an exothermic reaction.Formation of C—O—Ca is more easily than that of C—Ca—O and formation of Caromatic—Caromatic—Ca—O is more easily than that of Caromatic—C(O)—Ca—O.The C—C bond Mulliken populations in tar model compound radicals are reduced by 11.9%,10.5% and 15.5% in the case of a hydrogen atom removed,and those are 15.7%,14.3% and 16.3% in the case of two hydrogen atoms removed through the absorption of CaO.Catalytic ability of CaO acting on the tar model compound is in an order of phenol>benzene>toluene.展开更多
This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian mod...This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian model with different parameters,and the target is modeled as a subspace rangespread target model.The persymmetric structure is used to model the clutter covariance matrix,in order to reduce the reliance on secondary data of the designed detectors.Three adaptive polarimetric persymmetric detectors are designed based on the generalized likelihood ratio test(GLRT),Rao test,and Wald test.All the proposed detectors have constant falsealarm rate property with respect to the clutter texture,the speckle covariance matrix.Experimental results on simulated and measured data show that three adaptive detectors outperform the competitors in different clutter environments,and the proposed GLRT detector has the best detection performance under different parameters.展开更多
为探究黄河流域复合型灾害的特征及其风险演化模式,首先厘清复合型灾害的基本特征,基于黄河流域2000-2023年的1553条灾害数据,归纳出10种典型的灾害链演化路径。通过构建复合型灾害的复杂网络模型,运用基于节点相似度和标签传播的加权...为探究黄河流域复合型灾害的特征及其风险演化模式,首先厘清复合型灾害的基本特征,基于黄河流域2000-2023年的1553条灾害数据,归纳出10种典型的灾害链演化路径。通过构建复合型灾害的复杂网络模型,运用基于节点相似度和标签传播的加权网络社团划分算法(Weighted Network Community Division Method based on Node Similarity and Label Propagation,SLWCD)对网络节点进行分类,识别影响复合型灾害风险水平的关键节点。结果表明:洪涝灾害为黄河流域复合型灾害网络中的核心节点,具有最强的全局影响力;水污染事故较易受到自然灾害或首发事故的触发,干旱与地震则为黄河流域的高频灾害。聚类分析结果揭示了四类显著的效应机制,分别为:风雨沙灾害与社会安全事件的时空累积效应、各类灾害与公共卫生事件的级联效应、地质灾害与事故灾难的联动效应及土地问题对公共卫生事件的长期影响。此外,通过Python模拟,研究发现黄河流域复合型灾害网络中潜在路径长度大于4的灾害链条共有7646条。基于研究结果,提出了以下政策建议:增强灾害预警与应急响应能力,统筹跨部门协作,强化高风险区域的监测,推进生态保护与可持续发展,优化水资源与污染防控,采取综合适应策略应对气候变化,以有效提升黄河流域应对复合型灾害的能力。展开更多
基金Project(51276023)supported by the National Natural Science Foundation of China
文摘B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.The pathways of tar compound radical absorbed by CaO were determined firstly through comparing enthalpy changes of the absorption,and then Mulliken population changes were analyzed.The results show that the absorption of tar model compound radical and CaO is an exothermic reaction.Formation of C—O—Ca is more easily than that of C—Ca—O and formation of Caromatic—Caromatic—Ca—O is more easily than that of Caromatic—C(O)—Ca—O.The C—C bond Mulliken populations in tar model compound radicals are reduced by 11.9%,10.5% and 15.5% in the case of a hydrogen atom removed,and those are 15.7%,14.3% and 16.3% in the case of two hydrogen atoms removed through the absorption of CaO.Catalytic ability of CaO acting on the tar model compound is in an order of phenol>benzene>toluene.
基金supported by the National Natural Science Foundation of China(62371382,62071346)the Science,Technology&Innovation Project of Xiong’an New Area(2022XAGG0181)the Special Funds for Creative Research(2022C61540)。
文摘This paper focuses on the adaptive detection of range and Doppler dual-spread targets in non-homogeneous and nonGaussian sea clutter.The sea clutter from two polarimetric channels is modeled as a compound-Gaussian model with different parameters,and the target is modeled as a subspace rangespread target model.The persymmetric structure is used to model the clutter covariance matrix,in order to reduce the reliance on secondary data of the designed detectors.Three adaptive polarimetric persymmetric detectors are designed based on the generalized likelihood ratio test(GLRT),Rao test,and Wald test.All the proposed detectors have constant falsealarm rate property with respect to the clutter texture,the speckle covariance matrix.Experimental results on simulated and measured data show that three adaptive detectors outperform the competitors in different clutter environments,and the proposed GLRT detector has the best detection performance under different parameters.
文摘为探究黄河流域复合型灾害的特征及其风险演化模式,首先厘清复合型灾害的基本特征,基于黄河流域2000-2023年的1553条灾害数据,归纳出10种典型的灾害链演化路径。通过构建复合型灾害的复杂网络模型,运用基于节点相似度和标签传播的加权网络社团划分算法(Weighted Network Community Division Method based on Node Similarity and Label Propagation,SLWCD)对网络节点进行分类,识别影响复合型灾害风险水平的关键节点。结果表明:洪涝灾害为黄河流域复合型灾害网络中的核心节点,具有最强的全局影响力;水污染事故较易受到自然灾害或首发事故的触发,干旱与地震则为黄河流域的高频灾害。聚类分析结果揭示了四类显著的效应机制,分别为:风雨沙灾害与社会安全事件的时空累积效应、各类灾害与公共卫生事件的级联效应、地质灾害与事故灾难的联动效应及土地问题对公共卫生事件的长期影响。此外,通过Python模拟,研究发现黄河流域复合型灾害网络中潜在路径长度大于4的灾害链条共有7646条。基于研究结果,提出了以下政策建议:增强灾害预警与应急响应能力,统筹跨部门协作,强化高风险区域的监测,推进生态保护与可持续发展,优化水资源与污染防控,采取综合适应策略应对气候变化,以有效提升黄河流域应对复合型灾害的能力。
