From graduate schools to K-12 schools: the transformation of Chinese language teachers ---- Understanding the socialization process of novice Chinese language teachers in the U.S.

This study tried to understand how teacher education programs and the practices in American K-12 schools shaped beliefs and behaviors of Chinese language teachers through the theoretical framework of Lacey’s theory of teacher socialization. Under this overarching purpose of the study, the interactions these novice Chinese language teachers had within the contexts of their teacher training programs and K-12 schools were examined by analyzing the social strategies they applied in corresponding contexts. Seven novice Chinese language teachers with various language, educational, and work backgrounds were interviewed for this study. The findings from surveys and in-depth interviews revealed the teachers were trying to establish themselves as authorities in the profession of teaching. In addition, some seemingly contradictions on the interpretations and choices these participants made within both the contexts of graduate schools and K-12 schools disclosed these teachers’ demands on the practicality of the teacher education programs at graduate school level. The need for support, recognition, and appreciation at schools were expressed by the participants in this study as well. The findings of this study suggested that the graduate programs that collaborated teacher education with local schools would be beneficial for novice Chinese language teachers to have a smoother transition. Additionally, integrating all aspects of teacher knowledge in teacher education programs, especially the knowledge of themselves as language teachers and the teacher profession, was indicated by the findings of the study. Some contradictions on choices of social strategies between NS and NNS novice teachers of Chinese also provided some insights for school administrators in terms of understanding teacher candidates and establishing sustainable development environment for Chinese language programs in American K-12 schools

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

New investigation of Micro-fluidized bed: The effect of wall roughness and particle size on hydrodynamics regimes

International audienceThis study presents a new design for Micro-fluidized beds (MFBs), together with a new approach to their hydrodynamic analysis. Two 4 mm MFB reactors were manufactured from glass and resin (constructed by stereo-lithographic 3D printing), to assess the influence of wall roughness on the hydrodynamic characteristics. The novel 3D printing scheme ensures air tightness and good transparency of the reactor. Four types of glass, SiC, Al2O3 and TiO2, belonging to groups B, A/C and C from Geldart's classification, were used to investigate the influence of particle size on their fluidization behavior in MFBs. Three grades of MFB wall roughness were tested. Mechanical vibration energy was applied to the MFBs to improve the quality of fluidization, and to overcome wall friction and cohesive forces. Their hydrodynamic properties were obtained by analyzing pressure fluctuations in the time and frequency domains. The results show that only an appropriate increase in wall roughness was helpful for the suppression of slugging fluidization. The use of mechanical vibrations was found to promote the attenuation or destruction of plug phenomena, thus improving the quality of fluidization of Group A/C and C particles. The feasibility of fluidizing group A/C and C particles has thus been verified in a 3D printed MFB reactors

Influence of powder properties and mixing technique under different conditions, on the densification and thermal conductivity of AlN for solar thermal applications

International audienceIn this study, a novel approach is presented which can be utilized to enhance the thermal conductivity and densification of sintered AlN pellets. AlN pellets with a CaO additive were produced by spark plasma sintering. The influence of CaO powder properties such as particle size (micron-, submicron- and nano-scale), dispersion, flowability and structural characteristics, on the mixing behavior of AlN and CaO mixed powders, and on the porosity and thermal conductivity of AlN pellets, were investigated. Additionally, the influence of mixing conditions, including additive content and rotational speed in a novel high-shear mixer (Picomix), were studied and various mixing techniques were compared. The results indicate that when the CaO content of the AlN pellets is increased to 3 wt%, their thermal conductivity rises from 48.1 W/m·K to 112.9 W/m·K. This increase can be attributed to the formation of a liquid phase, and to a reduction in pellet porosity during sintering. Furthermore, when the rotational speed of the mixer is increased to 5000 rpm, the pellets’ thermal conductivity further rises to 126.2 W/m·K. This improvement is a result of the enhanced dispersion of CaO in the mixed powder. The shearing forces in the Picomix facilitate the coating of AlN particles with submicron- or nano-scale CaO particles, thereby improving the flowability of the mixed powder and narrowing the particle size distribution. This further improves the liquid phase distribution, thus enhancing the thermal conductivity of the AlN pellets (135.3 W/m·K). The novel high-shear mixer (Picomix) has demonstrated enhanced performance when compared with traditional mixing techniques (ball milling and manual mixing), since it involves a solvent-free process, is faster, has a lower energy consumption, causes less powder-oxidation and leads to a higher value of thermal conductivity, making it an excellent choice for the preparation of mixed powders for solar thermal applications