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1.
乏燃料贮存格架是核电厂贮存乏燃料的重要设备,在满载条件下和地震/跌落事故中,都应保持稳定和安全状态.本文基于LS-DYNA对乏燃料贮存格架进行了跌落事故冲击分析,考虑了最重重物从可能最高处意外跌落的情况.分析时考虑了碰撞、几何大变形、材料非线性等非线性因素.分析发现,浅跌落情况下贮存格架变形较大,但为局部变形,冲击载荷不影响贮存格架的安全功能.深跌落情况下,组件跌落在支座上方时支座承受的载荷最大,并在许用载荷范围内.为确保核电厂安全性和可靠性,基于分析得到的现象,设计和开展了乏燃料贮存格架浅跌落和深跌落试验.试验采用了等比例贮存腔和真实燃料组件的管座.同时对试验件进行了跌落分析,并与试验结果进行了对比,验证了分析技术的保守性和准确性.掌握的分析技术可应用于所有压水堆核电站乏燃料贮存格架的跌落事故分析. 相似文献
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通过三轴卸荷试验,探究了不同路径下卸荷速率对砂岩力学特性及破坏过程中的能量耗散的影响。试验结果表明在全过程应力-应变曲线的弹性阶段,轴向变形起主导作用,弹塑性阶段,环向应变的增加值大于轴向应变增加值。在围压卸荷阶段,卸荷速率越小,卸荷阶段的应变折合柔度越大,此时岩样的变形不充分,呈现明显的脆性破坏。恒主应力差路径下的耗散能大于恒轴压路径下的耗散能的35%,卸荷速率越大,岩样的弹性应变能越小。 相似文献
3.
Jing Tang Jun Li Peimei Da Yongcheng Wang Prof. Gengfeng Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11288-11299
Photoelectrochemical sensing represents a unique means for chemical and biological detection, with foci of optimizing semiconductor composition and electronic structures, surface functionalization layers, and chemical detection methods. Here, we have briefly discussed our recent developments of TiO2 nanowire‐based photoelectrochemical sensing, with particular emphasis on three main detection mechanisms and corresponding examples. We have also demonstrated the use of the photoelectrochemical sensing of real‐time molecular reaction kinetic measurements, as well as direct interfacing of living cells and probing of cellular functions. 相似文献
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The two-state reaction mechanism of the Pt4+/− with N2O (CO) on the quartet and doublet potential energy surfaces has been investigated at the B3LYP level. The effect of Pt4
− anion assistance is analyzed using the activation strain model in which the activation energy (ΔΕ
≠) is decomposed into the distortion energies
(\Updelta E 1 \textdist ) (\Updelta E^{ \ne }_{\text{dist}} ) and the stabilizing transition state (TS) interaction energies
(\Updelta E 1 \textint ) (\Updelta E^{ \ne }_{\text{int}} ) , namely
\Updelta E 1 = \Updelta E 1 \textdist + \Updelta E 1 \textint \Updelta E^{ \ne } = \Updelta E^{ \ne }_{\text{dist}} + \Updelta E^{ \ne }_{\text{int}} . The lowering of activation barriers through Pt4
− anion assistance is caused by the TS interaction
\Updelta E 1 \textint \Updelta E^{ \ne }_{\text{int}} (−90.7 to −95.6 kcal/mol) becoming more stabilizing. This is attributed to the N2O π*-LUMO and Pt d HOMO back-donation interactions. However, the strength of the back-donation interactions has significantly
impact on the reaction mechanism. For the Pt4
− anion system, it has very significant back-bonding interaction (N2O negative charge of 0.79e), HOMO has 81.5% π* LUMO(N2O) character, with 3d orbital contributions of 10.7% from Pt(3) and 7.7% from Pt(7) near the 4TS4 transition state. This facilitates the bending of the N2O molecule, the N–O bond weakening, and an O−(2P) dissociation without surface crossing. For the Pt4
+ cation system, the strength of the charge transfer is weaker, which leads to the diabatic (spin conserving) dissociation
of N2O: N2O(1∑+) → N2(1∑g+) + O(1D). The quartet to doublet state transition should occur efficiently near the 4TS1 due to the larger SOC value calculated of 677.9 cm−1. Not only will the reaction overcome spin-change-induced barrier (ca. 7 kcal/mol) but also overcome adiabatic barrier (ca.
40.1 kcal/mol).Therefore, the lack of a thermodynamic driving force is an important factor contributing to the low efficiency
of the reaction system. 相似文献
9.
Juanxia Kang Yongcheng Wang Jingjing Wu Zhiming Zhu 《International journal of quantum chemistry》2020,120(5):e26109
In order to further explore the detailed reaction mechanism of carbon dioxide activated by [Re(CO)2]+ complex, CCSD(T) methods was performed to determine related potential energy surface (PES). Crossing point is determined by using a partially optimized method. The result shows that larger spin-orbital coupling (155.37 cm−1) and intersystem crossing probabilities in spin-forbidden region causes the electron to spin flip at the minimum energy crossing point and access to the lower singlet PES. Nonadiabatic rate constant k is estimated to be quite rapid, so transition state (1TS1) is rate-controlled steps. In addition, the electronic structure of oxygen-atom transfer process is further analyzed by localized molecular orbital and Mayer bond order. The analysis finds that the form of main bonding orbital is the electron contribution from the p(O) in CO2 to the empty d(Re) orbital. 相似文献
10.
采用密度泛函理论UB3LYP方法对Co+在三重态及五重态势能面上催化N2O与C2H6进行循环反应的两态反应机理进行了研究. 运用Harvery方法优化了两自旋态势能面5个最低能量交叉点(MECP),计算了MECP处自旋-轨道耦合作用. 采用Landau-Zener公式计算了自旋翻转处的系间窜越几率,各MECP处均可发生有效系间窜越. 通过应用Kozuch提出的能量跨度模型,Co+催化N2O与C2H6在298K下反应生成CH3CHO时有最大的TOF值3.35×10-21 s-1. 相似文献