基于正则化与B样条曲线的桥梁影响线识别方法

为了快速评估既有桥梁的安全性,研究了基于多源实测信息快速准确识别桥梁影响线的方法。首先利用桥梁动力响应及车辆移动的实测信息,建立影响线识别的数学模型。在模型中引入Tikhonov正则化方法以解决病态矩阵求解问题,通过设置罚函数项以取得较光滑并贴近真实的影响线。然后通过基函数扩展法重构影响线,将其表示为一系列三次B样条基函数的线性组合,从而将问题从识别众多影响线因子简化为识别少量基函数权重系数。为了验证上述方法的可行性,先在实验室模拟钢制试验小车在钢筋混凝土三跨连续梁模型上移动的过程。基于实测布置于梁底的多测点挠度和应变响应时程以及相应的试验车信息,可识别出不同位置测点的挠度和应变影响线。试验结果表明无论是影响线的总体形状还是局部峰值,识别解与基准解均能较好地吻合。该方法还被进一步应用到一座简支现浇预应力混凝土箱梁桥。该试验通过实测检测车过桥期间的桥梁跨中截面若干测点的动应变、动挠度以及车辆重力、实时位置等信息,准确识别了对应于不同车道的挠度和应变影响线。通过对比桥梁静载实测和影响线虚拟加载结果,发现两者偏差绝对值在5%以内。在一定程度上表明了该影响线识别方法具有较高精度,并具备工程应用的良好潜力。国家自然科学基金项目(NSFC-51778550);;福建省自然科学基金项目(2017J01101);;厦门市科技局科技计划项目(3502Z20163002);;厦门大学校长基金项目(20720180060

Effect of Various Prepared Method on Catalytic Performance of Cu-Mn-Si/HZSM-5 Catalyst for CO_2 Hydrogenation

分别采用物理混和、共沉积法和超声共沉积法制备了Cu-Mn-Si/HZSM-5复合催化剂,并用XRD、BET、H2-TPR、H2-TPD和NH3-TPD等手段进行了表征,考察3种制备方法对催化剂催化加氢性能的影响。结果表明:超声共沉积法制备的Cu-Mn-Si/HZSM-5催化剂颗粒均匀、粒径小、催化性能最好。H2-TPR、H2-TPD和NH3-TPD分析表明,采用超声共沉积法制备催化剂,更能促进Cu(Ⅰ)、Cu(Ⅱ)之间的相互转换,增强了铜锰复合氧化物相互作用,有利于催化剂表面活性物种Cu+形成。同时,增强了对H2的吸附强度,使表面的酸度增强,促进了催化剂活性的提高。Cu-Mn-Si/HZSM-5 catalysts were prepared via the physical hybrid method,co-precipitation method and Ultrasonic co-precipitation method,and these catalysts were characterized by XRD,BET,H2-TPR,H2-TPDand NH3-TPD to analyse catalytic performance of the catalysts.The results showed that although sonication can not obviously change the physical structure of catalysts,it can make partical uniform and tiny,and.The results indicated that Cu-MnSi/HZSM-5 catalysts prepared by the Ultrasonic co-precipitation method had uniform grain,small grain size and the best catalytic capacity.H2-TPR,H2-TPD and NH3-TPD results suggested that it promote the creation of Cu+ on surface of catalyst and enhance the interaction of copper-manganese compound oxide so that active specie Cu are difficult to be reduced by ultrasonic co-precipitation method.At the same time,adsorption sites for H2 were increased,acidity of surface of catalyst was increased and acid sites were stronger,promoting enhancement of activity of catalyst

Study on Catalytic activity of Cu-Mn/HZSM-5 Catalyst for Dimethyl Ether Synthesis

研究不同铜锰比、助剂Si、Zr、Zn对Cu-Mn/HZSM-5催化剂在二氧化碳加氢合成二甲醚的催化活性的影响。结果表明,n(Cu)/n(Mn)的最佳值为4/3;助剂Si的加入能显著提高Cu-Mn/HZSM-5催化剂的性能,在2.0MPa、250℃、空速2100h-1;V(H2)/V(CO2)=3.2下,当催化剂中w(SiO2)=3.5%时,二氧化碳的转化率和二甲醚的收率分别为23.86%和9.33%。XRD和H2-TPR表明,适量SiO2的加入,使CuO晶相峰明显减弱,促进表面Cu的分散;铜锰复合氧化物进一步向非晶态转化,阻止Cu的深度还原,从而提高了催化剂的活性。在考察的范围内,最适宜的反应温度为260℃左右。提高氢碳比,有利于提高催化剂的催化活性。The influences of Cu/ Mn ratio and Si,Zr,Zn promoters on the performance of the Cu-Mn/HZSM-5 catalysts for CO2 hydrogenation to dimethyl ether were studied.It was found that the optimal molar ratio of Cu to Mn was 4/3,the addition of SiO2 promoter could obviously improve the performance of the Cu-Mn/HZSM-5 catalyst,and the optimized adding amount was 3.5% of the catalyst mass(calculated as oxides),with which 23.86% of the conversion of CO2 and 13.74% of the yield of DME were reached under 2.0MPa,250℃,GHSV 2100h1,volume ratio of 3.2 of H2 to CO2.The XRD and H2-TPR results suggested that the suitable introduction of SiO2 can make peak intensity of crystal phase CuO weaking,and promotes disperse of Cu.The copper-manganese compound oxide more translats into amorphous phase from crystal phase,and it prevents deep deoxidize of Cu.All of those results improv the activity of catalyst.The optimum reaction temperature is 260℃ in selected range.Increasing H2/CO2 volume ratio is helpful to improve the catalytic activity

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies