Analysis of the Aspiration Drag in Dual-Bell Nozzles

Yazhou Liu,Ping Li 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.2

The performance of dual-bell nozzles is affected by the aspiration drag generated in the recirculation zone during low-altitude operation. In this paper, dual-bell nozzles with different design parameters were studied by simulation to gain the aspiration drag at various flight altitudes. Results show that the aspiration drag of dual-bell nozzle with negative wall pressure gradient extension decreases with the increasing flight altitude, while the aspiration drag of dual-bell nozzles with zero and positive wall pressure gradient extensions first decreases and then increases with the increase of flight altitude. These phenomena are caused by opposite varying trends for the axial size of recirculation zone and the difference between the ambient pressure and the wall pressure in the recirculation zone during the ascent of flight altitude. Moreover, the aspiration drag can be reduced by increasing the length and area ratio of base nozzle contours and decreasing these parameters of nozzle extensions.

Environmental factors have a strong impact on the composition and diversity of the gut bacterial community of Chinese black honeybees

Yazhou Zhao,Yanping Chen,Zhiguo Li,Wenjun Peng 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.1

Acetylcholinesterase (AChE) plays a pivotal role in synaptic transmission by hydrolyzing the neurotransmitteracetylcholine. In addition to the classical function of AChE in synaptic transmission, various non-classicalfunctions have been elucidated. Unlike vertebrates possessing a single AChE gene (ace), invertebrates (nematodes,arachnids, and insects) have multiple ace loci, encoding diverse AChEs with a range of different functions. In the field of toxicology, AChE with synaptic function has long been exploited as the target of organophosphorusand cabarmate pesticides to control invertebrate pests for the past several decades. However, many aspects of theevolution and non-classical roles of invertebrate AChEs are still unclear. Although currently available informationon invertebrate AChEs is fragmented, we reviewed the recent findings on their evolutionary status,molecular/biochemical properties, and deduced non-classical (non-neuronal) functions. The Chinese black honeybees is an ecotype of the European honeybee that is formed by the natural hybridizationof Apis mellifera mellifera and A. m. carnica. It is distributed in nature reserves in North China and has been animportant breeding resource for disease resistance and other desirable traits. Compared to the areas outside ofreserves, the nature reserves offer significant biodiversity benefits not only to the Chinese black honey bees butalso to the other valuable plants and animals. In recent years there has been growing evidence that environmentalfactors including food choices play an important role in shaping the composition and activity of gutmicrobiota, which in turn can impact host health. In the previous studies on Chinse black honeybees, littleattention has been paid to the diverse population of microbes in the gut that play a vital role in host health. Inorder to achieve a better understanding on the role of environmental factors in diversity and composition of gutmicrobiota of honey bees, in the present study, we analyzed the gut bacterial communities of Chinese blackhoneybees using terminal restriction fragment length polymorphism (T-RFLP). The results showed that thesamples from the national nature reserves that are protected and managed so as to preserve and enrich theirnatural condition and resources for Chinese black honeybees had higher variety and richness of gut bacteria thanthat collected from unreserved regions that also harbor populations of Chinese black honeybees. The fourterminal restriction fragments (T-RFs), 201, 223, 247 and 320 bp, were identified to be the dominant bacteria ofChinese black honeybees. Of which 247 and 320 bp had greater differences between bee groups sampled indifferent regions and therefore could be used as genetic markers to separate samples collected from the nationalnature reserves to samples collected from unreserved regions. The results clearly indicate that national naturereserve protects biological diversity and ecological and evolutionary processes which have had a significantinfluence on the diversity of gut bacteria of Chinese black honeybees. The ubiquity of gut symbiotic bacteriaidentified in Chinese black honeybee suggests that environmental factors could play an important role in diversityand composition of gut bacteria and warrant further investigation into the functional significance of thesegut bacteria for the honeybee health.

Professional Competence Evaluation of Information Management Undergraduates Based on Rough Set and D-S Evidence Theory

Di Li,Hu Wang,Rui Wang,Yazhou Xiong 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.5

Based on the analysis of knowledge structure and factors that influence the professional competence of IMIS undergraduates, this paper selects 7 courses as evaluation indexes. Firstly, it gets 3 indexes of database theory, data oriented programming (C#), Management Information Systems as evidences through the method of information entropy reduction. Secondly, it improves the BPA of subjective experience by using rough set theory and gets an objective BPA. Finally, it uses D-S evidence theory to synthesize the evidence and evaluates the professional competence of IMIS undergraduates.

Experimental research on design wind loads of a large air-cooling structure

Xu Yazhou,Ren Qianqian,Bai Guoliang,Li Hongxing 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.4

Because of the particularity and complexity of direct air-cooling structures (ACS), wind parameters given in the general load codes are not suitable for the wind-resistant design. In order to investigate the wind loads of ACS, two 1/150 scaled three-span models were designed and fabricated, corresponding to a rigid model and an aero-elastic model, and wind tunnel tests were then carried out. The model used for testing the wind pressure distribution of the ACS was defined as the rigid model in this paper, and the stiffness of which was higher than that of the aero-elastic model. By testing the rigid model, the wind pressure distribution of the ACS model was studied, the shape coefficients of “A” shaped frame and windbreak walls, and the gust factor of the windbreak walls were determined. Through testing the aero-elastic model, the wind-induced dynamic responses of the ACS model was studied, and the wind vibration coefficients of ACS were determined based on the experimental displacement responses. The factors including wind direction angle and rotation of fan were taken into account in this test. The results indicated that the influence of running fans could be ignored in the structural design of ACS, and the wind direction angle had a certain effect on the parameters. Moreover, the shielding effect of windbreak walls induced that wind loads of the “A” shaped frame were all suction. Subsequently, based on the design formula of wind loads in accordance with the Chinese load code, the corresponding parameters were presented as a reference for wind-resistant design and wind load calculation of air-cooling structures.

Enhanced electrical conductivity of pitch-derived carbon via graphene template effects for high electrically conductive composites

Zhiping Lei,Yazhou Li,Zhao Lei,Xue Yang,Jingchong Yan,Zhanku Li,Hengfu Shui,Shibiao Ren,Zhicai Wang,Ying Kong,Shigang Kang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

Large-scale preparation of cheap and high-performance carbonaceous materials is in urgent need due tothe huge demand of carbonaceous materials-organic binder composites for Joule heating. Here, carbonbasedelectrothermal composites with high electrical conductivity were fabricated by adjusting the morphologyand structure of pitch-based carbonaceous materials (PC) through the use of graphene asstructure-directing agent to tune the orientation and carbonization of coal pitch. It is demonstrated thatthe addition of graphene can effectively promote the formation of graphitized carbon, increase the contentof sp2C, reduce defective carbon and increase the graphite interlayer spacing. 1% graphene-added PCPVDFcomposite exhibits 290% increase in the carrier concentration, 190% enhancement in mobility, and67% reduction in the volume resistivity compared to PC-PVDF composite. Molecular simulations elucidatethat the graphene edges favor pitch carbonization and improve the orientation factor and energy gap ofcarbon materials. This study provides clues for design of low-cost pitch-derived carbon materials-bindercomposites.

Moderating effect of regulatory focus on public acceptance of nuclear energy

Yanling He,Yazhou Li,Dongqin Xia,Tingting Zhang,Yongliang Wang,Li Hu,Jibao Gu,Yican Wu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.8

Public acceptance has become the most critical question for sustainable development of nuclear energy in recent decades. Many researches concentrated on risk and benefit perception, which were deemed as the most influential factors of Public Acceptance of Nuclear Energy (PANE). But few researches focused on psychological factors including regulatory focus. Therefore, this paper aimed to explore the moderating effect of regulatory focus on PANE based on Regulatory Focus Theory in order to find ways to increase/decrease PANE. An Internet-based survey had been carried out in China nationwide. The results indicated that trust in government was positively related to PANE and this relationship was mediated by risk and benefit perception. In addition, the strength of the associations between risk and benefit perception and PANE were moderated by regulatory focus, consisting of prevention focus and promotion focus. Pre-vention focus strengthened the negative relationship between risk perception and PANE, while pro-motion focus weakened. Moreover, promotion focus weakened the positive relationship between benefit perception and PANE, but no significant moderating effect of prevention focus was founded on the relationship between benefit perception and PANE. Some policy implications were also proposed on the basis of above-mentioned findings.

MiR-182-5p Mediated by Exosomes Derived From Bone Marrow Mesenchymal Stem Cell Attenuates Inflammatory Responses by Targeting TLR4 in a Mouse Model of Myocardial Infraction

Sun Chuang,Li Wei,Li Yanhong,Chen Jian,An Huixian,Zeng Guangwei,Wang Tingting,Guo Yazhou,Wang Changying 대한면역학회 2022 Immune Network Vol.22 No.6

Exosomes derived from mesenchymal stem cells (MSCs) could protect against myocardial infarction (MI). TLR4 is reported to play an important role in MI, while microRNA-182-5p (miR-182-5p) negatively regulates TLR4 expression. Therefore, we hypothesize that MSCs-derived exosomes overexpressing miR-182-5p may have beneficial effects on MI. We generated bone marrow mesenchymal stem cells (BM-MSCs) and overexpressed miR-182-5p in these cells for exosome isolation. H2O2-stimulated neonatal mouse ventricle myocytes (NMVMs) and MI mouse model were employed, which were subjected to exosome treatment. The expression of inflammatory factors, heart function, and TLR4 signaling pathway activation were monitored. It was found that miR-182-5p decreased TLR4 expression in BM-MSCs and NMVMs. Administration of exosomes overexpressing miR-182-5p to H2O2-stimulated NMVMs enhanced cell viability and suppressed the expression of inflammatory cytokines. In addition, they promoted heart function, suppressed inflammatory responses, and de-activated TLR4/NF-κB signaling pathway in MI mice. In conclusion, miR-182-5p transferred by the exosomes derived from BM-MSCs protected against MI-induced impairments by targeting TLR4.

A new method for safety classifi cation of structures, systems and components by refl ecting nuclear reactor operating history into importance measures

Jie Cheng,Jie Liu,Shanqi Chen,Yazhou Li,Jin Wang,Fang Wang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

Risk-informed safety classification of structures, systems and components (SSCs) is very important forensuring the safety and economic efficiency of nuclear power plants (NPPs). However, previous methodsfor safety classification of SSCs do not take the plant operating modes or the operational process of SSCsinto consideration, thus cannot concentrate on the safety and economic efficiency accurately. In thiscontribution, a new method for safety classification of SSCs based on the categorization of plant operating modes is proposed, which considers the NPPs operating history to improve the economic efficiencies while maintaining the safety. According to the time duration of plant configurations in plantoperating modes, average importances of SSCs are accessed for an NPP considering the operationalprocess, and then safety classification of SSCs is performed for plant operating modes. The correctnessand effectiveness of the proposed method is demonstrated by application in an NPP's safety classificationof SSCs

Risk-informed design optimization method and application in a lead-based research reactor

Jiaqun Wang,Qianglong Wang,Jinrong Qiu,Jin Wang,Fang Wang,Yazhou Li Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

Risk-informed approach has been widely applied in the safety design, regulation, and operation of nuclear reactors. It has been commonly accepted that risk-informed design optimization should be used in the innovative reactor designs to make nuclear system highly safe and reliable. In spite of the risk-informed approach has been used in some advanced nuclear reactors designs, such as Westinghouse IRIS, Gen-IV sodium fast reactors and lead-based fast reactors, the process of risk-informed design of nuclear reactors is hardly to carry out when passive system reliability should be integrated in the framework. A practical method for new passive safety reactors based on probabilistic safety assessment (PSA) and passive system reliability analyze linking is proposed in this paper. New three-dimension frequency-consequence curve based on risk concept with three variables is used in this method. The proposed method has been applied to the determination optimization of design options selection in a 10 MWth lead-based research reactor(LR) to obtain one optimized system design in conceptual design stage, using the integrated reliability and probabilistic safety assessment program RiskA, and the computation resources and time consumption in this process was demonstrated reasonable and acceptable.