Cavitation cloud dynamic characteristics of dual-chamber self-excited oscillatory waterjet

Dezheng Li,Yong Kang,Hanqing Shi,Yi Hu,Qi Liu,Hongchao Li,Jincheng Hu,Jiamin Li 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Aiming to enhance self-excited oscillating cavitation jet performance, the effect of the dual-chamber nozzlestructure on the jet dynamical characteristics was designed and investigated. With high-speed camera technology,the cavitation phenomenon was investigated to analyze the area pattern and shedding period of the cavitation cloudunder different nozzle structures. The results showed that the dual-chamber nozzle significantly improved the jet cavitationstrength, and the cavitation cloud area increased by 76% and decreased the shedding period by 90% comparedwith the single-chamber nozzle. In the upstream chamber, the upper shrinkage ratio had a more drastic effect on thecavitation cloud area and shedding frequency than the lower shrinkage ratio with a more sensitive effect on the sheddingfrequency. In the downstream chamber, the outlet diameter ratio and chamber diameter were more sensitive tothe regulation of cavitation cloud shedding frequency and area, respectively, with the optimal regulation at the outletdiameter ratio of 1 and chamber length of 6 mm. The chamber diameter modulated the cavitation cloud most drasticallywith a comprehensive performance optimum at 12mm, which the area fluctuation reached 76.8%. The resultsprovide a basis for further research and application of dual-chamber nozzles.

누가 백신을 맞는가: 기술수용모형(TAM)으로 살펴본 중국인들의 COVID-19 백신접종 결정요인들

손우비 ( Sun¸ Yufei ),호함경 ( Hu¸ Hanqing ),김태용 ( Kim¸ Taeyong ) 경희대학교 사회과학연구원 2021 社會科學硏究 Vol.47 No.1

본 연구는 기술수용모형을 이론적 틀로 삼아 접종의도의 개념과 그것에 영향력이 있을 것으로 예상되는 다양한 개념들을 측정하는 복수의 문항들로 구성된 설문을 통해 중국인들의 COVID-19 백신 접종의도를 결정하는 요인들이 무엇이었고 그 영향구조는 어떠한가를 규명하는 것을 목적으로 수행되었다. 중국 현지에서 수행된 조사 결과를 다각도로 분석한 연구자들은 다음과 같은 결론을 도출할 수 있었다: 첫째, 용이성은 무의미하며, 유용성 지각이 접종의도 형성에 중심역할을 한다. 백신은 분명 신기술이고 따라서 기술수용모형의 적용이 가능해야 하지만, 접종이라는 행동은 그 난이도가 현저히 낮아, 용이성이 큰 의미를 갖지 못한 것으로 해석된다. 둘째, 모든 영향의 원천은 건강관련 지식(헬스리터러시)과 위험지각(지각된 위험)으로 압축된다. 위험지각이 인간이 수집해 축적하는 관련 지식들에 의해 결정된다는 점을 상기할 때, 이는 대중을 대상으로 하는 국가 차원의 교육이 무엇보다 중요함을 시사한다. 셋째, 주관적 규범은 그 자체가 유용성과 접종의도에 미치는 영향에 더해, 헬스리터러시와 접종의도 그리고 지각된 위험과 접종의도 사이에서 의미 있는 중개역할을 한다. 또 하나의 주목할 만한 발견은 주관적 규범이 유용성에 미치는 긍정적 영향이 지각된 위험이 유용성에 미치는 부정적 영향보다 훨씬 크다는 사실이다. 본 연구는 기술수용모형이 백신접종 상황에도 적용이 가능하다는 점을 밝힌 이론적 의의에 더해, 정부가 ‘2021년 11월 국가 집단면역 완성’을 이루기 위해 무엇을 시도할 수 있는지를 제안해준 실무적 의의를 갖는다. The present study was performed to identify what factors determine the intention of Chinese people to get a COVID-19 vaccine and its effect structure with the data collected from an on-line survey conducted in China by employing the Technology Acceptance Model(TAM). The present researchers carried out a series of analyses with the data to draw the conclusions as follows: First, perceived ease of use seems meaningless in the situation in which the target behavior was to get a vaccine, while perceived usefulness played a central role in the formation of such intention. Second, all the impacts seemed derived from people’s health literacy and perceived risk. Third, in addition to its own influence on usefulness and intention, subjective norm plays a significant mediating role between health literacy and intention and between perceived risk and intention. Finally, noteworthy is that the positive impact of subjective norm on usefulness is far greater than the negative impact of perceived risk, meaning that meeting the expectations of those they value and care is considered much more useful than avoiding the risk they are to face. In addition to the theoretical significance of revealing that the TAM can be applied to an inoculation situation, this study has practical significance suggesting what the government can do in order to achieve its goal of completing national immunity by November 2021.

Experimental Study on Crack Propagation of Concrete Under Various Loading Rates with Digital Image Correlation Method

Jingwu Bu,Xudong Chen,Liangpeng Hu,Hanqing Yang,Saisai Liu 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3

The quantificational exploration of the propagation law of fracture process zone (FPZ) is of great importance to the research on concrete fracture. This paper performed fracture experiments on pre-cracked concrete beams under various loading rates. Digital image correlation (DIC) method was applied to obtain the whole field displacement of concrete in the fracture test. The crack opening displacement (COD) and the evolution of FPZ were determined based on the whole field displacement. The results show that the length of FPZ first increases and then decreases with the development of the effective crack length and the maximum length of FPZ is about 60 mm. It can be found that the length of FPZ corresponding to the peak load decreases with the increase of loading rates. Based on the fictitious crack model, a bilinear softening model was established. According to the proposed model, the mechanical behavior and the propagation law of FPZ were analyzed. The bilinear softening model can reflect the microcrack development and the aggregate interlocking in the FPZ.

Trapping tephritid fruit flies (Diptera: Tephritidae) in citrus groves of Fujian Province of China

Yulu Xia,Gecheng Ouyang,Xingli Ma,Bohua Hou,Jinghao Huang,Hanqing HU,Guocheng Fan 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.4

Certain tephritid fruit flies, such as the oriental fruit fly, Bactrocera dorsalis, the Chinese citrus fly, B. minax and the Japanese orange fly, B. tsuneonis (Diptera: Tephritidae: Dacinae), are destructive citrus pests in China. A twoyear trapping study was conducted in pomelo, Citrus maxima, groves in Fujian Province of China. The objectives of this study were to investigate the species, the abundance of tephritid fruit flies in the orchards, as well as the efficacy of the selected lure traps to these flies. Four lure traps or devices, i.e. methyl eugenol + Steiner trap (ST), cuelure + ST, ammonium acetate + putrescine + ST, and sticky spheres, were deployed from June to November 2017 and April to October 2018. Six economically significant Dacini pests were trapped during the period. These flies are B. dorsalis, the melon fruit fly, Zeugodacus cucurbitae, the pumpkin fruit fly, Z. tau, the Malaysian fruit fly, B. latifrons, and other two species - B. rubigina and Z. scutellatus. B. dorsalis was the most abundant, accounting for more than 50% of the capture, followed by Z. cucurbitae. The remaining four species accounted for less than 2% of the total capture. B. minax and B. tsuneonis, two destructive citrus-damaging tephritid fruit flies in China, were not found during the trapping period. Methyl eugenol trapped the highest number of fruit flies, followed by cuelure.

Intercropping garlic at different planting times and densities for insect pest or crop yield and value management in tobacco fields

Rongquan LAI,Chaozhi ZHU,Jingjing BAI,Xiaoting WU,Gang GU,Jianbao BAI,Ting ZHOU,Dingfeng WANG,Hanqing HU,Tianran LIN 한국곤충학회 2020 Entomological Research Vol.50 No.3

Although the densities of tobacco pests have been decreased in garlic-tobacco fields, further studies are needed to judge the effects of garlic transplanting densities or times on tobacco pests in tobacco fields. Therefore, field experiments were conducted in Liancheng County in Longyan City, Fujian Province, in China in 2014 and 2015. Myzus persicae (Sulzer) abundance, the species or abundance ratios of enemies and pests, the intercropping effects and the tobacco yield and crop value showed that the effects of transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter on pests were stronger than those of other treatments. Aphid abundance was significantly lower in transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter than in the other treatments. The ratio between enemies and pests in transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter was higher than those in the other treatments. The intercropping effects of transplanting tobacco 10 days after garlic transplantation at a density of 5.85 individual plants per square meter on Myzus persicae, Spodoptera litura (Fabricius), Heliothis assulta Guenee and Nezara viridula Linnaeus were significantly stronger than those of the other treatments, whereas the effects of transplanting tobacco 15 days after garlic transplantation at a garlic density of 5.85 individual plants per square meter on Agrotis ypsilon (Rottemberg) were significantly stronger. Additionally, the yield and crop value of transplanting tobacco 10 days after garlic was transplanted at a density of 5.85 individual plants m ̅2 were higher than those of the other treatments. Therefore, our study demonstrated that the model of transplanting tobacco 10 days after garlic was transplanted at a density of 5.85 individual plants m ̅2 is an optimal management strategy to control flue-cured tobacco pests and to acquire higher crop yield in garlic-tobacco fields.