Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional tr...Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surface deformation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is cond^ted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one.展开更多
In the paper, the establishment, measurement, data-processing program and monitoring accuracy of the GPS seismic monitoring network in North China, especially in the Capital-Circle area, have been presented briefly. T...In the paper, the establishment, measurement, data-processing program and monitoring accuracy of the GPS seismic monitoring network in North China, especially in the Capital-Circle area, have been presented briefly. The relation of horizontal crustal deformation to tectonic movement, stress-field variation and seismicity has been analyzed in detail. The results indicate that the accuracy of GPS measurement has reached the order of 10-9 and the annual rate of horizontal crustal deformation in North China is about 4 ~5 mm. Horizontal crustal movement is a direct indication of the regional stress field. Therefore, by monitoring the time-sequence variation of horizontal crustal motion, it would be possible to investigate the change in the stress field, to analyze the tendency of seismicity and to determine the seismogenic zones.展开更多
对移动通信终端进行侦察与管控是维护正常通信秩序和电磁空间安全的应有之义。通信系统的行为模式是其重要的特征之一,传统的仅限于信号参数获取的侦察方法无法对移动通信系统的行为模式进行精准分析。针对这一问题,以终端与基站交互过...对移动通信终端进行侦察与管控是维护正常通信秩序和电磁空间安全的应有之义。通信系统的行为模式是其重要的特征之一,传统的仅限于信号参数获取的侦察方法无法对移动通信系统的行为模式进行精准分析。针对这一问题,以终端与基站交互过程中寻呼(Paging)信号与接入(Access)信号为突破口,充分利用该类信号特有的时频特征和明文传输特点,在对其进行有效截获的基础上,经过解调、解扰、解码得到其携带的信息比特。通过对信息比特实施解析,获得交互信令的含义,完成对移动通信终端行为模式的综合分析,揭示了寻呼与接入信号之间通信信息交互的时序逻辑关系,为信息对抗中的灵巧干扰提供了时间与信息字段上的侦察引导,是后续灵巧干扰的基础与前提。最后利用通信侦察接收机对第五代移动通信(5th Generation mobile communication,5G)信号进行实地侦收与分析,实验结果验证了所提方法的正确性与有效性,为移动通信终端的精准侦察与管控奠定了技术基础。展开更多
Human nuclear receptor hB1F is a novel member of the fushi tarazu factor Ⅰ subfamily of nuclear receptor superfamily. The studies about its homologous genes indicate that hB1F may play a key role in regulating the me...Human nuclear receptor hB1F is a novel member of the fushi tarazu factor Ⅰ subfamily of nuclear receptor superfamily. The studies about its homologous genes indicate that hB1F may play a key role in regulating the metabolic homeostasis of cholesterol. After obtaining the founder mice carrying the trausgeue of hblf by microiujectiou, each founder was mated to normal C57 mouse and the positive F1 by PCR identification of the same founder were iutercrossed within sisters and brothers to establish the trausgeuic mouse lineage. The results of F1, F2 and offspring of test cross identification showed that the widely expressed hb1f trausgeuic mouse lineage was established successfully in this study. The tissue morphology of the trausgeuic lineage was also analyzed preliminarily.展开更多
文摘Numerical analysis of keyhole shape and keyhole establishment time is of great significance for selection and optimization of the process parameters in keyhole plasma arc welding. In this paper, a three-dimensional transient model is developed to analyze the evolutions of keyhole shape and keyhole establishment time in continuous current plasma arc welding process. Firstly, a combined volumetric heat source model is used to simulate the transient variation of temperature field. And then the surface deformation equation is adopted to calculate dynamic features of the keyhole shape and keyhole establishment time inside weld pool, in which the force action on weld pool surface is considered. Experiment is cond^ted to validate the numerical simulation results. The predicted keyhole size and keyhole establishment time are in agreement with the experimental measurement. And the calculated fusion zone geometry is consistent with the measured one.
文摘In the paper, the establishment, measurement, data-processing program and monitoring accuracy of the GPS seismic monitoring network in North China, especially in the Capital-Circle area, have been presented briefly. The relation of horizontal crustal deformation to tectonic movement, stress-field variation and seismicity has been analyzed in detail. The results indicate that the accuracy of GPS measurement has reached the order of 10-9 and the annual rate of horizontal crustal deformation in North China is about 4 ~5 mm. Horizontal crustal movement is a direct indication of the regional stress field. Therefore, by monitoring the time-sequence variation of horizontal crustal motion, it would be possible to investigate the change in the stress field, to analyze the tendency of seismicity and to determine the seismogenic zones.
文摘对移动通信终端进行侦察与管控是维护正常通信秩序和电磁空间安全的应有之义。通信系统的行为模式是其重要的特征之一,传统的仅限于信号参数获取的侦察方法无法对移动通信系统的行为模式进行精准分析。针对这一问题,以终端与基站交互过程中寻呼(Paging)信号与接入(Access)信号为突破口,充分利用该类信号特有的时频特征和明文传输特点,在对其进行有效截获的基础上,经过解调、解扰、解码得到其携带的信息比特。通过对信息比特实施解析,获得交互信令的含义,完成对移动通信终端行为模式的综合分析,揭示了寻呼与接入信号之间通信信息交互的时序逻辑关系,为信息对抗中的灵巧干扰提供了时间与信息字段上的侦察引导,是后续灵巧干扰的基础与前提。最后利用通信侦察接收机对第五代移动通信(5th Generation mobile communication,5G)信号进行实地侦收与分析,实验结果验证了所提方法的正确性与有效性,为移动通信终端的精准侦察与管控奠定了技术基础。
文摘Human nuclear receptor hB1F is a novel member of the fushi tarazu factor Ⅰ subfamily of nuclear receptor superfamily. The studies about its homologous genes indicate that hB1F may play a key role in regulating the metabolic homeostasis of cholesterol. After obtaining the founder mice carrying the trausgeue of hblf by microiujectiou, each founder was mated to normal C57 mouse and the positive F1 by PCR identification of the same founder were iutercrossed within sisters and brothers to establish the trausgeuic mouse lineage. The results of F1, F2 and offspring of test cross identification showed that the widely expressed hb1f trausgeuic mouse lineage was established successfully in this study. The tissue morphology of the trausgeuic lineage was also analyzed preliminarily.
