基于有限元仿真的发泡硅橡胶老化规律研究

通过力学性能测试得到发泡硅橡胶应力应变曲线,结合Ogden(Foam) 3阶超弹本构模型,建立发泡硅橡胶静密封系统的有限元仿真模型,得到大压缩量下发泡硅橡胶的von Mises应力及接触压力分布情况。仿真结果表明:大压缩量下发泡硅橡胶对称中心线位置的von Mises应力、接触压力值较大,在橡胶边缘和靠近限位环处接触应力数值有突增。开展140℃热空气老化试验,测定老化后发泡硅橡胶应力应变曲线,结合有限元仿真模型分析发泡硅橡胶老化后von Mises应力、接触压力的变化规律。结果表明:经过热空气老化后,在一定载荷下发泡硅橡胶等效应力和接触压力均呈增大的趋势。     

Degradation rate quantification of solid oxide fuel cell performance with and without Al2TiO5 addition

Degradation rates of electrical current during constant voltage operation of SOFCs with anodes made using NiO precursor powders from two different manufacturers with and without the addition of aluminum titanate (ALT) added by either mechanical mixing or anode infiltration have been quantified using a novel MATLAB algorithm. Because the algorithm has been used to quantify degradation rates for many different SOFC tests, it is thought that the method can be applied to most measured SOFC data to quantify the instantaneous cell degradation rate as a function of time for the entire SOFC performance measurement. Degradation rates determined at different times have been plotted against varying concentrations of ALT addition, facilitating the estimation of optimum ALT concentration for SOFC anodes made with NiO from a specific manufacturer. The algorithm used to determine degradation rates is available upon request to the corresponding author.     

An approach to measure infill matric suction of irregular infilled rock joints under constant normal stiffness shearing

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers (HCTs) during direct shear of infilled joints under constant normal stiffness (CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using three-dimensional (3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients (JRCs) of 8–10 and 18–20 with the ratios of infill thickness to asperity height (t/a) equal to 0.5 were investigated. Matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.     

压水堆核电厂一回路首次钝化工艺研究

压水堆核电厂热态功能试验中的一回路首次钝化对核电厂一回路材料腐蚀控制和减少腐蚀产物等方面具有重要作用。本文结合理论研究与工程实际情况，提出了在热态功能试验过程中钝化膜的生成包含电化学反应和化学反应的观点，阐述了双层膜的生长机理，解释了用电化学测试方法分析钝化工艺过程的合理性，推导出钝化温度与钝化膜反应速率的函数关系式，钝化温度升高，反应速率升高，钝化时间缩短；明确了钝化工艺温度的理论限值应不低于260℃。      

氨基羟基脲脉冲辐解研究

研究了脉冲辐解过程中氨基羟基脲与水辐解活性粒子（e^-_aq、·OH和·H）及单电子氧化剂·CO₃^-的反应动力学过程。反应近似为准一级反应，反应速率常数分别为k（e^-aq）=1.41×10⁸ L/(mol·s)、k（·OH）=1.05×10¹⁰ L/(mol·s)、k（·H）=2.68×10⁵ L/(mol·s)、k（·CO^-₃）=4.25×10⁸ L/(mol·s)。其中氨基羟基脲与·OH的反应速率常数最大，故在辐解过程中其为主要反应。     

球化退火工艺对高碳马氏体不锈钢8Cr13MoV组织及性能的影响

为了优化高碳马氏体不锈钢8Cr13MoV的球化热处理工艺,提高其退火后的冷加工性能,采用微观组织分析法以及拉伸力学分析法研究了球化退火过程中奥氏体化保温时间和冷却速率对8Cr13MoV钢的球化效果影响。结果表明, 随着奥氏体保温时间的增加,组织中细颗粒状碳化物数量减少,索氏体数量增多,试样硬度先降低后升高,但断后伸长率持续增加;随冷却速率增加,试样组织中细颗粒状碳化物和索氏体数量、硬度和强度增加,断后伸长率降低。综合对比,奥氏体保温时间ϕ90 min时试样综合力学性能较好,冷却速率应控制在25 ℃·h^-1以内。与奥氏体保温时间相比,冷却速率对力学性能的影响更加显著。     

Insight into selective oxidation of dual-phase steel after annealing in pure H2 atmosphere at different heating rates and temperatures

In this paper, the oxidation behaviors of DP980 advanced high strength steel (AHSS) are studied during annealing in a hydrogen atmosphere with different temperatures and heating rates. It is revealed that with the increase in holding time, the different heating rates affecting the surface oxide precipitation on the strip surface will be weakened. Mass transfer of Mn in heating, soaking, and cooling stages has been considered to illustrate the effect of heating rate on the oxide morphology of steel. And then, the Wagner model and aluminothermic reaction kinetics were performed to discuss the transition from external to internal and maximum reduction diameter of MnO oxidation.     

In Silico Study on Tumor-Size-Dependent Thermal Profiles inside an Anthropomorphic Female Breast Phantom Subjected to Multi-Dipole Antenna Array

Electromagnetic hyperthermia as a potent adjuvant for conventional cancer therapies can be considered valuable in modern oncology, as its task is to thermally destroy cancer cells exposed to high-frequency electromagnetic fields. Hyperthermia treatment planning based on computer in silico simulations has the potential to improve the localized heating of breast tissues through the use of the phased-array dipole applicators. Herein, we intended to improve our understanding of temperature estimation in an anatomically accurate female breast phantom embedded with a tumor, particularly when it is exposed to an eight-element dipole antenna matrix surrounding the breast tissues. The Maxwell equations coupled with the modified Pennes’ bioheat equation was solved in the modelled breast tissues using the finite-difference time-domain (FDTD) engine. The microwave (MW) applicators around the object were modelled with shortened half-wavelength dipole antennas operating at the same 1 GHz frequency, but with different input power and phases for the dipole sources. The total input power of an eight-dipole antenna matrix was set at 8 W so that the temperature in the breast tumor did not exceed 42 °C. Finding the optimal setting for each dipole antenna from the matrix was our primary objective. Such a procedure should form the basis of any successful hyperthermia treatment planning. We applied the algorithm of multi for multi-objective optimization for the power and phases for the dipole sources in terms of maximizing the specific absorption rate (SAR) parameter inside the breast tumor while minimizing this parameter in the healthy tissues. Electro-thermal simulations were performed for tumors of different radii to confirm the reliable operation of the given optimization procedure. In the next step, thermal profiles for tumors of various sizes were calculated for the optimal parameters of dipole sources. The computed results showed that larger tumors heated better than smaller tumors; however, the procedure worked well regardless of the tumor size. This verifies the effectiveness of the applied optimization method, regardless of the various stages of breast tumor development.     

焦油渣性质评价与加氢裂化性能研究

焦油渣中挥发的有机烃类化合物易造成较为严重的环境问题,对焦油渣的较高处理成本导致其仍未能被有效处理与合理利用,因而有必要对焦油渣的性质和高附加值利用进行研究。对2种不同煤炭加工技术在生产中获得的焦油渣进行性质分析,并对焦油渣在高温高压下加氢裂化性能进行研究,即加氢裂化反应后得到的气体产物采用组分分析后得到气产率,对液固产物进行萃取分离后可得到不同条件下加氢裂化反应的氢耗、气产率、液相物产率和四氢呋喃不溶物的转化率。通过对不同加工途径所产生焦油渣的性质进行研究可发现,大多数焦油渣含有10%以上的水分和20%以上的焦油,焦化和气化工艺所产焦油渣中的灰分较高而中低温热解焦油渣的灰分相对较低,且其甲苯不溶物和四氢呋喃不溶物均高于中低温热解焦油渣。由2种典型焦油渣在不同的工艺条件、催化剂和供氢介质作用下加氢裂化的实验结果表明:通过改变工艺条件和催化剂,中低温热解焦油渣中95%以上的组分均能被裂解为轻质化合物,气化焦油渣中四氢呋喃可溶解的组分也能够进一步被裂解为轻质组分,而其固含物却难以再被进一步地裂解。