One of the most important safety features of nuclear facilities is the shielding material used to protect the operating personnel from radiation exposure. The most common materials used in radiation shielding are conc...One of the most important safety features of nuclear facilities is the shielding material used to protect the operating personnel from radiation exposure. The most common materials used in radiation shielding are concretes. In this study, a Monte Carlo N-Particle eXtended code is used to calculate the gamma-ray attenuation coefficients and dose rates for a new concrete material composed of MnFe_2O_4 nanoparticles, which is then compared with the theoretical and experimental results obtained for a SiO_2 nanoparticle concrete material. According to the results, the average relative differences between the simulations and the theoretical and experimental results for the linear attenuation coefficient(l) in the SiO_2 nanoparticle materials are 6.4% and 5.5%, respectively. By increasing the SiO_2 content up to 1.5% and the temperature of MnFe_2O_4 up to 673 K, l is increased for all energies. In addition, the photon dose rate decreases up to 9.2% and3.7% for MnFe_2O_4 and SiO_2 for gamma-ray energies of0.511 and 1.274 MeV, respectively. Therefore, it was concluded that the addition of SiO_2 and MnFe_2O_4 nanoparticles to concrete improves its nuclear properties and could lead to it being more useful in radiation shielding.展开更多
The classification for handwritten Chinese character recognition can be viewed as a transformation in discrete vector space. In this paper, from the point of discrete vector space transformation, a new 4-corner codes ...The classification for handwritten Chinese character recognition can be viewed as a transformation in discrete vector space. In this paper, from the point of discrete vector space transformation, a new 4-corner codes classifier based on decision tree inductive learning algorithm ID3 for handwritten Chinese characters is presented. With a feature extraction controller, the classifier can reduce the number of extracted features and accelerate classification speed. Experimental results show that the 4-corner codes classifier performs well on both recognition accuracy and speed.展开更多
Investigating the time-dependent behavior of nuclear reactors during loss of flow accidents is necessary for safety assessment.Coupled neutronic/thermal-hydraulic codes are used to simulate a full three-dimensional mo...Investigating the time-dependent behavior of nuclear reactors during loss of flow accidents is necessary for safety assessment.Coupled neutronic/thermal-hydraulic codes are used to simulate a full three-dimensional model and predict the essential safety parameters.MCNP6/ANSYS-FLUENT17.2 coupled scheme is used in the present study to simulate a three-dimensional model for VVER-1000 assembly and analyze its behavior during a LOFA(loss of flow accident).Three LOFA scenarios are proposed to represent the failure of one,two or three of the coolant pumps.The influence of the accident on the reactivity and axial power distribution of the assembly is determined considering thermal-hydraulic feedbacks.Then the data obtained are provided to the thermal-hydraulic code to calculate the actual temperature values.The results of the study showed that the developed coupling scheme granted an actual and precise description of the axial behavior of the assembly during LOFA.The output data obtained from both neutronic and thermal-hydraulic calculations have a strong feedback effect;this demonstrated the effect of data exchange between codes to predict accurate values for the main safety parameters.Moreover,it revealed the importance of studying the detailed axial distribution of the safety parameters for the reactor assessment during accidents rather than taking average values in calculations.展开更多
In this paper, according to the AR4JA codes in deep space communication, two kinds of iterative decoding including partly parallel decoding and overlapped partly parallel decoding are analyzed, and the advantages and ...In this paper, according to the AR4JA codes in deep space communication, two kinds of iterative decoding including partly parallel decoding and overlapped partly parallel decoding are analyzed, and the advantages and disadvantages of them are listed. A modified overlapped partly parallel decoding that not only inherits the advantages of the two algorithms, but also overcomes the shortcomings of the two algorithms is proposed. The simulation results show that the three kinds of decoding have the same decoding performance; modified overlapped partly parallel decoding improves the iterative convergence rate and the throughput of system.展开更多
【目的】旨在分析血清4型禽腺病毒(fowl adenovirus serotype 4,FAdV-4)感染鸡肝癌细胞(leghorn male hepatoma cell,LMH)后长链非编码RNA(lncRNA)的表达谱变化,并研究lncRNA在FAdV-4感染过程中的潜在调控作用。【方法】利用FAdV-4感染...【目的】旨在分析血清4型禽腺病毒(fowl adenovirus serotype 4,FAdV-4)感染鸡肝癌细胞(leghorn male hepatoma cell,LMH)后长链非编码RNA(lncRNA)的表达谱变化,并研究lncRNA在FAdV-4感染过程中的潜在调控作用。【方法】利用FAdV-4感染LMH细胞,感染24 h后收集细胞,并设置未感染细胞为对照组。对细胞样本进行转录组测序,筛选出差异表达lncRNA,对其靶基因进行GO(gene ontology,GO)功能和KEGG(Kyoto encyclopedia of genes and genomes,KEGG)信号通路富集分析,利用实时荧光定量PCR验证随机挑选的5个lncRNA。【结果】差异表达分析筛选出302条lncRNA,其中118条lncRNA表达水平显著上调,184条lncRNA表达水平下调。GO功能分析显示,差异表达lncRNA的靶基因主要富集在细胞过程、单体过程、催化活性和核酸结合转录因子活性等生物学过程;KEGG通路分析显示,差异表达lncRNA主要富集在TGF-β和glucagon等信号通路。RT-qPCR结果表明,被验证的5个lncRNA表达水平与测序结果趋势一致,验证了测序结果的可靠性。【结论】本研究结果对FAdV-4感染LMH细胞的lncRNA表达谱进行分析,为探究lncRNA可能参与FAdV-4感染过程的调控及其调控机制提供数据支持。展开更多
文摘One of the most important safety features of nuclear facilities is the shielding material used to protect the operating personnel from radiation exposure. The most common materials used in radiation shielding are concretes. In this study, a Monte Carlo N-Particle eXtended code is used to calculate the gamma-ray attenuation coefficients and dose rates for a new concrete material composed of MnFe_2O_4 nanoparticles, which is then compared with the theoretical and experimental results obtained for a SiO_2 nanoparticle concrete material. According to the results, the average relative differences between the simulations and the theoretical and experimental results for the linear attenuation coefficient(l) in the SiO_2 nanoparticle materials are 6.4% and 5.5%, respectively. By increasing the SiO_2 content up to 1.5% and the temperature of MnFe_2O_4 up to 673 K, l is increased for all energies. In addition, the photon dose rate decreases up to 9.2% and3.7% for MnFe_2O_4 and SiO_2 for gamma-ray energies of0.511 and 1.274 MeV, respectively. Therefore, it was concluded that the addition of SiO_2 and MnFe_2O_4 nanoparticles to concrete improves its nuclear properties and could lead to it being more useful in radiation shielding.
文摘The classification for handwritten Chinese character recognition can be viewed as a transformation in discrete vector space. In this paper, from the point of discrete vector space transformation, a new 4-corner codes classifier based on decision tree inductive learning algorithm ID3 for handwritten Chinese characters is presented. With a feature extraction controller, the classifier can reduce the number of extracted features and accelerate classification speed. Experimental results show that the 4-corner codes classifier performs well on both recognition accuracy and speed.
文摘Investigating the time-dependent behavior of nuclear reactors during loss of flow accidents is necessary for safety assessment.Coupled neutronic/thermal-hydraulic codes are used to simulate a full three-dimensional model and predict the essential safety parameters.MCNP6/ANSYS-FLUENT17.2 coupled scheme is used in the present study to simulate a three-dimensional model for VVER-1000 assembly and analyze its behavior during a LOFA(loss of flow accident).Three LOFA scenarios are proposed to represent the failure of one,two or three of the coolant pumps.The influence of the accident on the reactivity and axial power distribution of the assembly is determined considering thermal-hydraulic feedbacks.Then the data obtained are provided to the thermal-hydraulic code to calculate the actual temperature values.The results of the study showed that the developed coupling scheme granted an actual and precise description of the axial behavior of the assembly during LOFA.The output data obtained from both neutronic and thermal-hydraulic calculations have a strong feedback effect;this demonstrated the effect of data exchange between codes to predict accurate values for the main safety parameters.Moreover,it revealed the importance of studying the detailed axial distribution of the safety parameters for the reactor assessment during accidents rather than taking average values in calculations.
基金Sponsored by the National Natural Science Foundation of China( Grant No. 61032003)the Fundamental Research Funds for the Central Universities( Grant No. HIT. NSRIF.2012021)
文摘In this paper, according to the AR4JA codes in deep space communication, two kinds of iterative decoding including partly parallel decoding and overlapped partly parallel decoding are analyzed, and the advantages and disadvantages of them are listed. A modified overlapped partly parallel decoding that not only inherits the advantages of the two algorithms, but also overcomes the shortcomings of the two algorithms is proposed. The simulation results show that the three kinds of decoding have the same decoding performance; modified overlapped partly parallel decoding improves the iterative convergence rate and the throughput of system.
文摘【目的】旨在分析血清4型禽腺病毒(fowl adenovirus serotype 4,FAdV-4)感染鸡肝癌细胞(leghorn male hepatoma cell,LMH)后长链非编码RNA(lncRNA)的表达谱变化,并研究lncRNA在FAdV-4感染过程中的潜在调控作用。【方法】利用FAdV-4感染LMH细胞,感染24 h后收集细胞,并设置未感染细胞为对照组。对细胞样本进行转录组测序,筛选出差异表达lncRNA,对其靶基因进行GO(gene ontology,GO)功能和KEGG(Kyoto encyclopedia of genes and genomes,KEGG)信号通路富集分析,利用实时荧光定量PCR验证随机挑选的5个lncRNA。【结果】差异表达分析筛选出302条lncRNA,其中118条lncRNA表达水平显著上调,184条lncRNA表达水平下调。GO功能分析显示,差异表达lncRNA的靶基因主要富集在细胞过程、单体过程、催化活性和核酸结合转录因子活性等生物学过程;KEGG通路分析显示,差异表达lncRNA主要富集在TGF-β和glucagon等信号通路。RT-qPCR结果表明,被验证的5个lncRNA表达水平与测序结果趋势一致,验证了测序结果的可靠性。【结论】本研究结果对FAdV-4感染LMH细胞的lncRNA表达谱进行分析,为探究lncRNA可能参与FAdV-4感染过程的调控及其调控机制提供数据支持。
