Development of a displacement-reactivity feedback model for dynamic behavior simulation in fast burst reactor

In this study, a displacement-reactivity feedback model, which can directly represent the inherent ‘‘thermal expansion extinction effect'' of fast burst reactors(FBRs),was developed with the aid of the static neutron transport component of the FBR-MPC code. Dynamic behaviors of bursts in the Godiva I reactor were simulated by coupling the simplified multiphysics models consisting of the point kinetic equations for neutronics, adiabatic equation for temperature, and thermoelastic equations for displacement/stress with the developed model. The results were compared with the corresponding experimental data and those obtained using the traditional fission yield(temperature rise)-reactivity feedback models. It was found that the developed model can provide good results for the bursts with no or a small inertia effect. For the bursts with a prominent inertia effect, the smaller burst width and asymmetric distribution of the fission rate curve, noticed in the experiments but not evident using the traditional models, can be reproduced. In addition, the realistic oscillations in reactivity and fission rate caused by the core vibration, as well as the deeper sub-prompt criticality in the plateau following the burst, can be observed. Therefore, the developed displacement-reactivity feedback model can be expected to be an effective tool for calculating the dynamic behaviors of bursts.

The Clinical Investigation of Pemetrexed Plus Carboplatin as an Active and Tolerable Treatment Plan in Chinese Elderly Patients with Advanced Lung Adenocarcinoma

The standard chemotherapy for Chinese elderly patients with non-small cell lung cancer (NSCLC) remains undefined. The study was to evaluate the therapeutic effects as well as side effects of pemetrexed plus carboplatin regimen as the first-line therapy for Chinese elderly patients with advanced lung adenocarcinoma. Twenty-three Chinese elderly patients (male 14 and female 9, average age 73.7 years, range 70~81 years) with advanced lung adenocarcinoma received pemetrexed plus carboplatin as the first-line therapy, in detail, pemetrexed 500 mg/m2 and carboplatin AUC 5 mg/ml/m2 were given intravenously on day 1. The treatment was repeated everyday in the 21 days cycle. Therapeutic effects were evaluated at least after two cycles of treatment. The remission rate, disease control rate, time to progression and overall survival were observed. The results showed that all the cases were valid for response evaluation, with the complete remission 0 case, partial remission 8 cases, stabilize disease 9 cases and progression disease 6 cases. The remission rate (including complete remission and partial remission) was 34.8%, disease control rate 73.9%, the time to progression was 5.8 months and the overall survival 13.7 months. There showed the positive relationship between the curative effects (either time to progression or overall survival) and chemotherapy cycles. The main toxicities were bone marrow suppression, nausea and vomiting. There was no chemotherapy-related death. The data suggested that the combination regimen with pemetrexed plus carboplatin is an active and tolerable treatment plan for Chinese elderly patients with advanced lung adenocarcinoma, in which the side effects were tolerable and manageable.

甲烷氧化偶联制乙烯Na–W–Mn/SiO_(2)催化剂的研究进展

乙烯产量是衡量一个国家石油化工行业水平的重要指标.因此,将甲烷高效转化为乙烯的甲烷氧化偶联(OCM)反应成为催化工业和能源领域的热门话题,甲烷氧化偶联工艺也已成为世界各国的研究热点.然而OCM反应是同时结合了多相反应和均相反应的复杂反应网络,使得OCM反应高效催化剂的开发面临着重大挑战.其中, Na–W–Mn/SiO_(2)体系催化剂是目前综合性能最好的催化剂,但Na–W–Mn/SiO_(2)催化剂组分复杂,反应所需温度高,活性中心仍存在争议.因此本文主要总结讨论了该体系催化剂上OCM反应机理,以及氧物种和酸碱性对OCM反应的影响.并详细介绍了体系中各活性组分在反应中的作用,以及各种原位表征手段在OCM机理研究中的应用.最后对OCM反应在高温原位表征,低温可控OCM反应以及化学链循环反应方向进行了展望.

Design method for hypersonic bump inlet based on transverse pressure gradient

Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consists of two steps.First,a parametric optimization approach is employed to design a series of 2D inlets with various compression efficiencies.Then,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump inlet.This method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric parameters.By performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/inlet.Results show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure recovery.In addition,the starting ability is significantly improved by adding the bump surface.Analysis reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted inlet.Finally,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow capture.The results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.

Effects of bump parameters on hypersonic inlet starting performance

Unstart is an unwanted flow phenomenon in a hypersonic inlet. When an unstart occurs, the captured airflow flowing through the engine significantly decreases with strong unsteady characteristics, which may lead to thrust loss or even combustor flameout. In this study, various bump configurations were designed to be integrated with a hypersonic inlet to improve its starting ability. A bump was defined as an integrated 3D compression surface installed upstream of the inlet entrance. The starting processes of these bump inlets were numerically simulated to investigate the effect laws and flow mechanisms of the bump parameters. Tests on bump height revealed that the starting performance could be significantly improved by increasing bump height, with the starting Mach number decreasing by 0.55 for the inlet with the highest bump. The high bump facilitates the side movement of the subsonic flow in the separation zone, which leads to a small separation bubble, thus accelerating the starting process. Further, the starting ability can be improved by designing a relatively wide bump, which results in a decline in the starting Mach number by 0.44. When the bump has the same or greater width compared with the airflow capture range, a growing spillage along the transverse direction can be formed so that the airflow in the separation bubble can be easily excluded, improving the starting ability.