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( Na Li ),( Yiming Cao ) 한국수학교육학회 2015 수학교육연구 Vol.19 No.1
In the present study, the changes of mathematics teachers`` verbal feedback between ten years ago and later were examined using a coding scheme on the types of teacher verbal feedback. Based on the analysis, it is found that teachers intend to use encouraging strategies to make responses to students ten years later. In addition, the duration used in communication between the teacher and individual student is being longer while the frequency of communication becomes less compared ten years ago. Meanwhile, the difference between good lesson ten years ago and common lesson ten years later is not so apparent. It can be inferred that the quality of teaching has being developed.
Na Li,Lingfeng Sun,Dong Chen 한국섬유공학회 2019 Fibers and polymers Vol.20 No.1
As structure materials, carbon fibre/benzoxazine (CF/BZ) composites are prone to damage, which compromises their structural performance significantly. Scarf repair is an effective means of restoring structure performance. In this paper, one side scarf repair CF/BZ (OR-CF/BZ) and both sides scarf repair CF/BZ (BR-CF/BZ) were prepared to investigate the influence of repair geometry on low velocity impact response of adhesively bonded scarf repair in damaged CF/BZ laminates. The intent of prepare BR-CF/BZ is to reduce the repair area. The CF/BZ laminates are removed the damage areawith a rectangle cutout from one side and two sides respectively and repaired with scarf patches. Low velocity impact with different impact energy levels are performed to investigate the impact performance of repaired composites. Visual and CScan inspection are conducted, in order to observe the extent of the damage in the repaired composites. Compression after impact (CAI) are undertaken to measure their residual strength. Micro-graphs of the specimen’s cross-section are also produced in an effort to observe the fractured sections and characterized the various fracture mechanisms involved. Resultsshow that the damage areas after impact of BR-CF/BZ is larger than that of OR-CF/BZ and CF/BZ. The penetrating damage of CF/BZ, OR-CF/BZ and BR-CF/BZ occur at 40 J, 50 J and 60 J impact energy respectively. The CAI strength of BR-CF/BZ is higher than that of OR-CF/BZ and CF/BZ. While the CAI modulus does not change greatly. The failure mechanism includes impact damage failure and growth of compressive failure during CAI test. The impact point is the most seriously damaged zone of the CAI specimens.
Na Li,Yu-Qun Han,Wen-Jing He,Shan-Liang Zhu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.8
In this paper, the full state constraints and input delay of stochastic nonlinear systems are studied. A new adaptive control algorithm is proposed using backstepping approach and multi-dimensional Taylor network (MTN) method. Firstly, the input delay problem is dealt with by introducing a new variable using the Padé approximation with Laplace transform. Secondly, MTNs are employed to approximate unknown nonlinear functions, and the barrier Lyapunov functions (BLFs) are constructed to deal with the state constraints. Based on this, a new approximation-based adaptive controller is proposed. Thirdly, it is proved that the proposed control method can ensure that all signals in the closed-loop system are semi-global ultimately uniformly bounded (SGUUB) in probability and the tracking error converges to a small neighborhood of the origin. Finally, two simulation examples are given to illustrate the effectiveness of the proposed design method.
( Na Li ),( Ramesh Kakarla ),( Jung Mi Moon ),( Booki Min ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7
Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/g- COD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-CODsubstrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation.
Na Li,Jing Xie,Yuan Ming Chu 한국식품과학회 2023 Food Science and Biotechnology Vol.32 No.8
Myofibril proteins degradation constitutes an important factor in quality deterioration, procedural activation or inhibition of endogenous protease potential regulates autolytic proteolysis-induced softening of post mortem fish muscle. Based on the brief introduction of myofibril proteins degradation in fish skeletal muscle, a detailed description of the main myofibril degradation properties and the distinct role played by endogenous proteases were proposed, which reflects the limitations and challenges of the current research on myofibril hydrolysis mechanisms based on the varied surrounding conditions. In addition, the latest researches on the evaluation method of myofibril proteins degradation were comprehensively reviewed. The potential use of label-free proteomics combined with bioinformatics was also emphasized and has become an important means to in-depth understand protein degradation mechanism.
Influence of the Upstream Terrain on the Formation of a Cold Frontal Snowband in Northeast China
Na Li,Baofeng Jiao,Lingkun Ran,Zongting Gao,Shouting Gao 한국기상학회 2022 Asia-Pacific Journal of Atmospheric Sciences Vol.58 No.2
We investigated the influence of upstream terrain on the formation of a cold frontal snowband in Northeast China. We conducted numerical sensitivity experiments that gradually removed the upstream terrain and compared the results with a control experiment. Our results indicate a clear negative effect of upstream terrain on the formation of snowbands, especially over large-scale terrain. By thoroughly examining the ingredients necessary for snowfall (instability, lifting and moisture), we found that the release of mid-level conditional instability, followed by the release of low-level or near surface instabilities (inertial instability, conditional instability or conditional symmetrical instability), contributed to formation of the snowband in both experiments. The lifting required for the release of these instabilities was mainly a result of frontogenetic forcing and upper gravity waves. However, the snowband in the control experiment developed later and was weaker than that in the experiment without upstream terrain. Two factors contributed to this negative topographic effect: (1) the mountain gravity waves over the upstream terrain, which perturbed the frontogenetic circulation by rapidly changing the vertical motion and therefore did not favor the release of instabilities in the absence of persistent ascending motion; and (2) the decrease in the supply of moisture as a result of blocking of the upstream terrain, which changed both the moisture and instability structures leeward of the mountains. A conceptual model is presented that shows the effects of the instabilities and lifting on the development of cold frontal snowbands in downstream mountains.