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Uncertainty analysis of heat transfer of TMSR-SF0 simulator
Jiajun Wang,Ye Dai,Yang Zou,Hongjie Xu Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.2
The TMSR-SF0 simulator is an integral effect thermal-hydraulic experimental system for the development of thorium molten salt reactor (TMSR) program in China. The simulator has two heat transport loops with liquid FLiNaK. In literature, the 95% level confidence uncertainties of the thermophysical properties of FLiNaK are recommended, and the uncertainties of density, heat capacity, thermal conductivity and viscosity are ±2%, ±10, ±10% and ±10% respectively. In order to investigate the effects of thermophysical properties uncertainties on the molten salt heat transport system, the uncertainty and sensitivity analysis of the heat transfer characteristics of the simulator system are carried out on a RELAP5 model. The uncertainties of thermophysical properties are incorporated in simulation model and the Monte Carlo sampling method is used to propagate the input uncertainties through the model. The simulation results indicate that the uncertainty propagated to core outlet temperature is about ±10 ℃ with a confidence level of 95% in a steady-state operation condition. The result should be noted in the design, operation and code validation of molten salt reactor. In addition, more experimental data is necessary for quantifying the uncertainty of thermophysical properties of molten salts.
( Liangliang Wang ),( Jiajun Wang ),( Hao Shi ),( Huaxiang Gu ),( Yu Zhang ),( Xun Li ),( Fei Wang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.6
Glycerol dehydrogenases (GlyDHs) are essential for glycerol metabolism in vivo, catalyzing its reversible reduction to 1,3-dihydroxypropranone (DHA). The gldA gene encoding a putative GlyDH was cloned from Thermoanaerobacterium thermosaccharolyticum DSM 571 (TtGlyDH) and expressed in Escherichia coli. The presence of Mn(2+) enhanced its enzymatic activity by 79.5%. Three highly conserved residues (Asp(171), His(254), and His(271)) in TtGlyDH were associated with metal ion binding. Based on an investigation of glycerol oxidation and DHA reduction, TtGlyDH showed maximum activity towards glycerol at 60°C and pH 8.0 and towards DHA at 60°C and pH 6.0. DHA reduction was the dominant reaction, with a lower Km(DHA) of 1.08 ± 0.13 mM and Vmax of 0.0053 ± 0.0001 mM/s, compared with glycerol oxidation, with a Km(glycerol) of 30.29 ± 3.42 mM and Vmax of 0.042 ± 0.002 mM/s. TtGlyDH had an apparent activation energy of 312.94 kJ/mol. The recombinant TtGlyDH was thermostable, maintaining 65% of its activity after a 2-h incubation at 60°C. Molecular modeling and site-directed mutagenesis analyses demonstrated that TtGlyDH had an atypical dinucleotide binding motif (GGG motif) and a basic residue Arg(43), both related to dinucleotide binding.
Yi Wang,Kai Wang,Jiajun Hu,Kang Si,Hongyan Xia 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.6
Thermal interface materials with high thermal conductivity are the best choice to solve the current overheating problem of electronic devices, and the choice of thermal conductive fi ller is a key factor aff ecting the performance of thermal interface composites. Hexagonal boron nitride sheet is considered to be ideal thermal conductive fi ller, but the thermal conductive eff ect of single fi ller is still insuffi cient to meet actual needs. Here, a new type of hybrid fi ller mixed with boron nitride sheet and boron phosphide particles is used to prepare epoxy based composites. When the fi ller volume fraction is 40%, the thermal conductivity of composites reaches 3.18 W m −1 K −1 . Under the same content, the thermal conductivity of the composites with mixed fi llers outperforms those with boron nitride sheet alone. At the same time, the composite material shows high breakdown strength of 46 kV mm −1 . This work provides a new way to prepare thermal interface materials with high thermal conductivity for modern electronic packaging.
Wang Tingting,Yang Yang,Liu Xinyue,Deng Jiajun,Wu Junqi,Hou Likun,Wu Chunyan,She Yunlang,Sun Xiwen,Xie Dong,Chen Chang 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.4
Objective: To investigate the association between CT imaging features and survival outcomes in patients with primary invasive mucinous adenocarcinoma (IMA). Materials and Methods: Preoperative CT image findings were consecutively evaluated in 317 patients with resected IMA from January 2011 to December 2015. The association between CT features and long-term survival were assessed by univariate analysis. The independent prognostic factors were identified by the multivariate Cox regression analyses. The survival comparison of IMA patients was investigated using the Kaplan-Meier method and propensity scores. Furthermore, the prognostic impact of CT features was assessed based on different imaging subtypes, and the results were adjusted using the Bonferroni method. Results: The median follow-up time was 52.8 months; the 5-year disease-free survival (DFS) and overall survival rates of resected IMAs were 68.5% and 77.6%, respectively. The univariate analyses of all IMA patients demonstrated that 15 CT imaging features, in addition to the clinicopathologic characteristics, significantly correlated with the recurrence or death of IMA patients. The multivariable analysis revealed that five of them, including imaging subtype (p = 0.002), spiculation (p < 0.001), tumor density (p = 0.008), air bronchogram (p < 0.001), emphysema (p < 0.001), and location (p = 0.029) were independent prognostic factors. The subgroup analysis demonstrated that pneumonic-type IMA had a significantly worse prognosis than solitary-type IMA. Moreover, for solitary-type IMAs, the most independent CT imaging biomarkers were air bronchogram and emphysema with an adjusted p value less than 0.05; for pneumonic-type IMA, the tumors with mixed consolidation and ground-glass opacity were associated with a longer DFS (adjusted p = 0.012). Conclusion: CT imaging features characteristic of IMA may provide prognostic information and individual risk assessment in addition to the recognized clinical predictors.
Empirical Study on the Influences of Rural Land Circulation on Grain Security
Xu Jiajun,Wang Mingzhe 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.12
Focusing on the phenomenon that rural land circulation has translated farmland into non-agricultural and non-grain land in recent years, this paper tries to theoretically solve the significant practical issue of sharp reduction in farmland caused by urbanization and grain security that is badly in need of solution in China through constructing models to study the relations between rural land circulation and grain security. As an important part of national security, grain security is a key strategic issue concerning national economy and the people’s livelihood. Grain security, energy security and financial security are called three major kinds of economic security in the world. In 2014, China’s grain output reached 607.10 million tons, seeing increases for 11 consecutive times, but the self-sufficiency rate of grain reduced to under 90%, and the grain supply gap continued to widen. To this end, the CPC Central Committee has proposed the new national grain security strategy of “Self-centered, state-based, capacity-guaranteed, and technology-supported with appropriate import” and taken important measures to strengthen land circulation and expand business scale. However, in theory, the issues whether agricultural production has scale operation and whether scale operation can increase grain output have remained controversial for a long time. In reality, China’s rural land circulation proportion in 2014 reached 28.8%, but the phenomena of non-grain farmland and non-agricultural farmland become serious. Therefore, this paper shows significance in both theory and practice with regard to the study on the relations between China’s grain security and rural land circulation as well as relevant policies. Through construction of Nerlove model of grain supply response, quantitative analysis is conducted to study the influences of rural land circulation on grain safety and relevant policies and suggestions are proposed in this paper.
Anelastic and Microplastic Damping of an Mg–Zn–Y–Al Alloy
Diqing Wan,Jiajun Hu,Yinglin Hu,Houbin Wang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.1
In this study, the Mg97Zn1Y2–Al alloy was selected as a high damping material, anelastic and microplastic damping wereanalyzed by studying strain amplitude-dependent damping curves of the alloy. The C1and C2values of the Granato–Lücke(G–L) model, the theoretical basis of anelastic damping, can be calculated for each alloy, then, the corresponding numbersof strong and weak pinners are deduced. However, since the occurrence of microplastic damping in a high strain amplitudecannot be explained by the G–L model, a new microplastic damping theory was introduced, by comparing the activationvolume of the material dislocation slip, the microplastic damping capacity of the Mg97Zn1Y2–xwt%Al (x = 0.3, 1, 3) alloysat the microplastic stage are compared. The elastic and plastic deformation of the materials could be sensitively reflected bystudying the damping behavior of these two stages