30 results on '"Chen, Jintao"'
Search Results
2. Two birds with one stone strategy of 2D MOF derived heterostructure for supercapacitor and electromagnetic absorption applications
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Wang, Wenxuan, Liu, Yuliang, Ke, Jinning, Chen, Jintao, He, Xinliang, Shi, Jia, Liu, Dong, Zhou, Shuxian, Niu, Rubao, and Yang, Naitao
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- 2025
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3. Ultrafast-response H2S MEMS gas sensor based on double phase In2O3 monolayer particle film
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Zhang, Yanlin, Zhang, Zheng, Lv, Guoliang, Zhang, Yu, Chen, Jintao, Luo, Yuanyuan, and Duan, Guotao
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- 2024
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4. Grain refinement and anisotropy improvement of arc-directed energy deposited Ti–6Al–4V with oscillating laser
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Cai, Yuhua, Peng, Zilong, Chen, Jintao, Chen, Hui, and Xiong, Jun
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- 2024
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5. Sustainable production 3-bromobutyrates and 3-hydroxybutyrates from bioderived poly-3-hydroxybutyrate
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Kang, Shimin, Tang, Peifeng, Liang, Jianhao, Fu, Jinxia, Chen, Jintao, Zheng, Xiting, Wang, Juntao, Ye, Jun, and Xu, Yongjun
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- 2023
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6. Oxidation of norbornadiene: Theoretical investigation on H-atom abstraction and related radical decomposition reactions
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Chen, Jintao, Liu, Mingxia, Zhu, Yuxiang, Jin, Kairu, Tian, Zhenyu, Yang, Lijun, and Zhou, Chong-Wen
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- 2023
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7. The anisotropy of high cycle fatigue property and fatigue crack growth behavior of Ti–6Al–4V alloy fabricated by high-power laser metal deposition
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Lv, Hang, Zhang, Zhenlin, Chen, Yarong, Liu, Yan, Chen, Hui, Chen, Yong, Cheng, Jing, She, Jian, He, Huabing, and Chen, Jintao
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- 2022
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8. Cyclic plastic deformation mechanism and cyclic hardening model of Sanicro 25 steel welded joint
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Li, Haizhou, Chen, Jintao, Chen, Hui, Xu, Lianyong, and Wang, Qingyuan
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- 2021
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9. Magnetic carbon nanotubes-molecularly imprinted polymer coupled with HPLC for selective enrichment and determination of ferulic acid in traditional Chinese medicine and biological samples
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Fu, Lulu, Chen, Qiu, Chen, Jintao, Ren, Liqin, Tang, Lan, and Shan, Weiguang
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- 2021
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10. Decoration of hollow nitrogen-doped carbon nanofibers with tapered rod-shaped NiCo2S4 as a 3D structural high-rate and long-lifespan self-supported anode material for potassium-ion batteries
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Zhang, Wenming, Chen, Jintao, Liu, Yiqun, Liu, Siming, Li, Xiaoting, Yang, Kun, and Li, Ling
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- 2020
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11. Head-of-bed positioning in large artery acute ischemic stroke
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Sharma, Vijay, Tan, Benjamin, Yeo, Leonard, Chan, Bernard, Jing, Mingxue, Wong, Lily, Chen, Jintao, Halik, Hariz, Sharma, Arvind, and Meenakshi, P.V.
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- 2023
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12. Thermal concentrating efficiency enhanced for multilayer circular thermal concentrators with gradient structures.
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Hou, Maoxiang, Chen, Jintao, Xie, Bin, Chen, Yun, and Chen, Xin
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DISTRIBUTION (Probability theory) , *THERMAL efficiency , *THERMAL conductivity , *METAMATERIALS , *FORECASTING - Abstract
• A gradient distribution-based multi-layer annular thermal concentrator structure design method was proposed, which can significantly improve the thermal concentration efficiency by adjusting the thermal conductivity and layer thickness distribution gradient, with an 8.56 % improvement over the single-layer structure. • An optimization strategy combining stepwise refinement search and machine learning prediction was adopted, which greatly improved the optimization efficiency and can be applied to the design and development of other thermal element structure devices. • The influence mechanism of the inner and outer layer structure on the thermal concentration efficiency was revealed, providing a theoretical basis for further optimization of the thermal concentrator structure. The thermal concentrating efficiency of a thermal concentrator is determined by the ratio of its interior to exterior temperature gradients, serving as a crucial indicator influenced by the interaction of geometrical and thermal conductivity parameters. Finding simpler and more effective ways to improve thermal concentrating efficiency has been a key concern in this field. In our study, we present a method to enhance the concentrating efficiency of an isotropic multilayer circular thermal concentrator by introducing gradient-distributed thermal conductivities or layer thicknesses within the multilayer circular structure. Our goal is to identify the optimal structural setup parameters for achieving enhanced thermal concentrating efficiency using an optimization approach that combines stepwise refinement search with machine-learning predictions. Initial investigations explore the impacts of different gradient schemes on thermal concentration performance. The gradient distribution function with high thermal concentrating efficiency is established through the stepwise refinement search strategy and the machine-learning model. Subsequently, a detailed search process is carried out in small increments, followed by finite element simulations to validate the thermal concentrating efficiency and ascertain the optimal design parameters of the thermal concentrator. Our findings reveal that the optimally designed gradient thermal concentrator showcases an 8.56 % increase in thermal concentrating efficiency compared to a single-layer structure without gradients. Moreover, applying the gradient function to the outer and inner rings elucidates the inherent influence of the inner and outer layered ring structures on thermal concentrating efficiency. The optimization methodology, combining stepwise refinement search and machine-learning predictions, succeeds in improving the efficiency with easy, fast and efficient operation. This approach can be extended to advance the development of various other thermal metastructured devices. [ABSTRACT FROM AUTHOR]
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- 2024
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13. Multi-objective optimization of morphology for high-rise residential cluster with the regards to energy use and microclimate.
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Feng, Weijia, Chen, Jintao, Yang, Yi, Gao, Weijun, Xing, Haowei, and Yu, Shuai
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ENERGY consumption , *PARETO analysis , *URBAN morphology , *SOLAR energy , *DIRECT costing - Abstract
Urban morphology significantly influences building energy consumption, solar energy potential, and outdoor thermal microclimate. This study seeks to optimize the urban morphology of high-rise residential clusters, using a framework that emphasizes energy use, outdoor thermal microclimate and incremental investment cost at a preliminary stage of design. The proposed framework is based on performance oriented parametric simulation and implements multi-objective optimization using the Grasshopper platform to assess residential cluster morphology. The study analyzed the five morphological parameters (floor area ratio (FAR), building density (BD), average floor (AF), average orientation (AO), and average aspect ratio (AAR)) to achieve the minimize of the Net Energy Intensity (NEI), Universal Thermal Climate Index (UTCI), and Incremental Investment Cost (IIC) of residential clusters. This approach aims to enhance energy efficiency and improve summer microclimate while reducing investment costs. Additionally, analyzed the correlation between morphological parameters and three key performance metrics: Energy Use Intensity (EUI) (encompassing heating, cooling, and lighting requirements), Photovoltaic Energy Generation (PVEG), and UTCI. The findings reveal that the optimal morphology of residential clusters varies significantly depending on the desired objective. When prioritizing PVEG, a morphology characterized by low height, high density, and a small aspect ratio is recommended. It is noteworthy that in this morphology, the cluster also demonstrates optimal UTCI during the summer. Conversely, if EUI is the primary objective, a configuration with higher height and aspect ratio, along with lower density, is suggested. On the other hand, balancing the requirements of these three objectives may require a moderately-spaced layout with low height, large aspect ratio, and compact front-to-back building spacing. Under these morphologies, particular attention should be given to the layout in the north–south directions. Furthermore, southward orientation is advisable. Additionally, based on analysis of Pareto solutions, a FAR of approximately 2.6 to 2.7 is recommended. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Robust cascaded horizontal-plane trajectory tracking for fixed-wing unmanned aerial vehicles.
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Yang, Wenlong, Chen, Jintao, Zhang, Zonggang, Shi, Zongying, and Zhong, Yisheng
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DRONE aircraft , *TRANSLATIONAL motion , *SIGNAL theory , *CLOSED loop systems , *NONLINEAR equations , *HYPERSONIC planes - Abstract
This paper investigates the problem of horizontal-plane trajectory tracking for fixed-wing unmanned aerial vehicles(UAVs) subjected to external disturbances and uncertainties including coupling and unmodeled dynamics. Under the assumption there exist ideal inner-loop controllers, the 12-state model is reduced to a 6-state translational motion model, which is described by a group of simplified nonlinear equations with equivalent disturbances via introducing general aerodynamic models. Then a new cascaded control structure consisting of an outer-loop controller for position control and inner-loop controllers for attitude and thrust control is proposed. Based on feedback linearization technology and signal compensation theory, the proposed controller applied for position control incorporates a nominal linear time-invariant controller and a robust compensator, the latter of which is introduced to restrain the effects of uncertainties and disturbances. The robust performance of the closed-loop system is proved. Actual experimental results conducted on a small fixed-wing aircraft demonstrate that the proposed control approach is effective. [ABSTRACT FROM AUTHOR]
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- 2022
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15. The clinical outcome of COVID-19 is strongly associated with microbiome dynamics in the upper respiratory tract.
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Xie, Linlin, Luo, Gengyan, Yang, Zhongzhou, Wu, Wei-chen, Chen, Jintao, Ren, Yuting, Zeng, Zhikun, Ye, Guangming, Pan, Yunbao, Zhao, Wen-jing, Chen, Yao-qing, Hou, Wei, Sun, Yanni, Guo, Deying, Yang, Zifeng, Li, Jun, Holmes, Edward C., Li, Yirong, Chen, Liangjun, and Shi, Mang
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The respiratory tract is the portal of entry for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although a variety of respiratory pathogens other than SARS-CoV-2 have been associated with severe cases of COVID-19 disease, the dynamics of the upper respiratory microbiota during disease the course of disease, and how they impact disease manifestation, remain uncertain. We collected 349 longitudinal upper respiratory samples from a cohort of 65 COVID-19 patients (cohort 1), 28 samples from 28 recovered COVID-19 patients (cohort 2), and 59 samples from 59 healthy controls (cohort 3). All COVID-19 patients originated from the earliest stage of the epidemic in Wuhan. Based on a modified clinical scale, the disease course was divided into five clinical disease phases (pseudotimes): "Healthy" (pseudotime 0), "Incremental" (pseudotime 1), "Critical" (pseudotime 2), "Complicated" (pseudotime 3), "Convalescent" (pseudotime 4), and "Long-term follow-up" (pseudotime 5). Using meta-transcriptomics, we investigated the features and dynamics of transcriptionally active microbes in the upper respiratory tract (URT) over the course of COVID-19 disease, as well as its association with disease progression and clinical outcomes. Our results revealed that the URT microbiome exhibits substantial heterogeneity during disease course. Two clusters of microbial communities characterized by low alpha diversity and enrichment for multiple pathogens or potential pathobionts (including Acinetobacter and Candida) were associated with disease progression and a worse clinical outcome. We also identified a series of microbial indicators that classified disease progression into more severe stages. Longitudinal analysis revealed that although the microbiome exhibited complex and changing patterns during COVID-19, a restoration of URT microbiomes from early dysbiosis toward more diverse status in later disease stages was observed in most patients. In addition, a group of potential pathobionts were strongly associated with the concentration of inflammatory indicators and mortality. This study revealed strong links between URT microbiome dynamics and disease progression and clinical outcomes in COVID-19, implying that the treatment of severe disease should consider the full spectrum of microbial pathogens present. • The URT microbiome exhibits complex and changing patterns during COVID-19. • A series of microbes are identified to be associated with more severe disease stages. • There are strong links between URT microbiome dynamics and disease progression. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Cullin-3 intervenes in muscle atrophy in the elderly by mediating the degradation of nAchRs ubiquitination.
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Chen, Jintao, Xu, Qun, Wang, Xinyi, Xu, Zherong, and Chen, Xujiao
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SARCOPENIA , *MUSCLE weakness , *MUSCULAR atrophy , *MYONEURAL junction , *QUALITY of life , *OLDER people - Abstract
Sarcopenia involves in the loss of muscle mass associated with aging, which is the major cause of progressive muscle weakness and deterioration in older adults. Muscle atrophy is a direct presentation of sarcopenia, and it greatly contributes to the decline in quality of life among older adults. Neuromuscular junction (NMJ) stability is the key link to maintain muscle function. Besides, the degenerative change of NMJ promotes the process of muscle atrophy in the elderly. Based on previous transcriptome sequencing and bioinformatics analyses of aged muscle, this study used the 18-month-old aged mouse model and the 6-month-old young mouse model to deliberate the role and underlying mechanisms of Cullin-3 (Cul3) in age-related muscle atrophy. The results of reverse transcriptase polymerase chain reaction (RT-PCR) and immunoblotting analysis showed that the expression of CUL3 increased in aged muscle tissue, while the expression level of postsynaptic membrane nicotinic acetylcholine receptors (nAChRs) decreased significantly, which manfested a negative correlation. Meanwhile, immunofluorescence demonstrated that Cul3 was highly expressed in senile muscle NMJ. The results of ubiquitin indicated that the ubiquitin level of aged muscle nAChRs was evidently increased. Co-immunoprecipitation furtherly verified the correlation between Cul3 and nAChRs. Taken together, Cul3 may mediate the ubiquitination degradation of nAChRs protein at the NMJ site in aged mice, leading to NMJ degeneration and accelerated atrophy of fast-twitch muscle fibers in aged muscle. As a prominent element to maintain the stability of NMJ, Cul3 is supposed to be one of candidate intervention targets in sarcopenia. • To investigate the expression, role and potential mechanism of Cullin-3 (Cul3) in age-related muscular atrophy. • Clarify the correlation between Cul3 and nAChRs, Cul3 may be involved in ubiquitin degradation of nAChRs at the NMJ site. • Cul3 mediated NMJ degeneration may lead to accelerated atrophy of muscle fibers in aging muscles, leading to sarcopenia. [ABSTRACT FROM AUTHOR]
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- 2023
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17. Robust formation control for uncertain multi-agent systems.
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Chen, Jintao, Shi, Zongying, and Zhong, Yisheng
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MULTIAGENT systems , *UNCERTAIN systems , *LINEAR systems , *STATE formation - Abstract
Robust formation problems for linear multi-agent systems with uncertainties and external disturbances are investigated in this paper. The model of each agent can be described by a nominal linear system combined with external disturbances and uncertainties which include parameter perturbations and nonlinear uncertainties. A more general bound of uncertainties is introduced. A robust formation controller, which consists of a nominal controller and a robust compensator, is proposed to achieve the desired state formation and restrain the influence of uncertainties and disturbances. Furthermore, sufficient conditions for time-varying formation feasibility are introduced and proved. Finally, a numerical example is provided to demonstrate the theoretical results. [ABSTRACT FROM AUTHOR]
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- 2019
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18. A study on weld morphology and periodic characteristics evolution of circular oscillating laser beam welding of SUS301L-HT stainless steel.
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Zhao, Xu, Chen, Jintao, Zhang, Weihua, and Chen, Hui
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LASER welding , *STAINLESS steel welding , *PLASMA arc welding , *WELDING , *COMPUTATIONAL fluid dynamics , *FLOW velocity - Abstract
• Weld morphology characteristics of circular oscillating laser beam welding (OLBW) was illustrated; • Variations of keyhole characteristics and molten pool morphology of circular OLBW were elucidated; • Flow pattern of circular OLBW at distinct moments was described. Many studies have identified the periodicity of oscillating laser beam welding (OLBW), but they do not provide a deep perspective to show the periodic changes of molten pool and keyhole characteristics. In the process of circular OLBW, the spatters were easily formed due to the unstable melt generated by rapid change in keyhole velocity, and its number was prone to decrease with the increase of frequency. The computational fluid dynamics (CFD) method successfully predicted the cross-section morphology of the weld, and the prediction deviation was small. In a single cycle, the fusion state between the newly generated melt and the existing molten pool determined the morphology of molten pool boundary, showing a 'W-U-W' shape change. The keyhole first destabilized and then stabilized again, and its depth exhibited a 'V' shape. The average flow velocity of the melt in the longitudinal section of the weld or keyhole center presented a 'W' shape. The keyhole depth or the average melt velocity period was equal to the oscillation period of circular OLBW. [ABSTRACT FROM AUTHOR]
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- 2023
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19. A study on the flow behavior and bubble evolution of circular oscillating laser welding of SUS301L-HT stainless steel.
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Zhao, Xu, Chen, Jintao, Lei, Zheng, Zhang, Weihua, and Chen, Hui
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STAINLESS steel welding , *LASER welding , *BUBBLES , *SURFACE tension , *TURBULENT flow , *LAMINAR flow - Abstract
The flow characteristics, bubble formation and inhibition mechanisms of circular oscillating laser beam welding (OLBW) at distinct stages were elucidated in present work. The formation processes of bubbles mainly included the following manners. First, one or more of vortex P2, the recoil pressure flow P3, the migration flows FMF and BMF impinged the keyhole wall. The necking generated, gradually destabilized, and finally collapsed. Second, the self-instability of needle-like keyhole bottom (NKB) with large curvature induced the bubble formation. Third, complex melt flow broke the abnormal deformation of the keyhole or the bubble wall to form a new bubble. The bubble suppression mechanisms were summarized to three categories. First, the recoil pressure on the inner wall of bubble was at a low level, and the volume of bubble continually decreased until it collapsed. Second, high recoil pressure penetrated the metal liquid bridge between keyhole and bubble. Third, when recoil pressure was greater than the resultant force between surface tension and melt dynamic pressure, the bubble constantly fluctuated and gradually merged with the moving keyhole. As the frequency increased from 10 Hz to 200 Hz, porosity showed an exponential decrease from 7.16% to 0.35% in circular oscillation mode. A unified porosity prediction curve based on the Reynolds number was built with a coefficient of determination of 0.989. When fluid changed from laminar to turbulent flow, the critical Reynolds number was set as 1000, the predicted porosity was 0.912%, and the critical frequencies in circular and infinite oscillation modes were 143 Hz or 115 Hz, respectively, which were consistent with experiment results. [ABSTRACT FROM AUTHOR]
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- 2023
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20. Deformation behavior and microstructure characteristics of the laser-welded Ti-6Al-4V joint under variable amplitude fatigue.
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Chen, Jintao, Li, Haizhou, Liu, Yingzong, Zhao, Xu, Cai, Yuhua, Chen, Hui, Chen, Yarong, Feng, Aixin, Wang, Hao, and Sun, Zhongtao
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MICROSTRUCTURE , *FATIGUE limit , *CRACK initiation (Fracture mechanics) , *DEFORMATIONS (Mechanics) , *STRESS concentration , *TITANIUM alloys - Abstract
The deformation behavior and microstructure characteristics of laser-welded Ti-6Al-4V titanium alloy joints under variable amplitude fatigue ranging from 320 to 380 MPa (initial maximum stress) were investigated in steps of 10 MPa. Each fatigue test included three different stages: the maximum stress amplitude was initial one for the first stage, but increased by 1.2 and 1.4 times for the second and third stages, respectively. The results showed that the variable amplitude fatigue limit of laser-welded the Ti-6Al-4V joint was 339 ± 5 MPa. Fractography analysis revealed that the fatigue cracks originated from the surface in the weld metal (WM) and were caused by the differences of grain size and texture orientation between WM and heat-affected zone. The average grain size of WM was significantly larger than that of other regions. Acicular α' martensite was distributed mainly in the coarse grains of WM and its orientation was more concentrated, leading to the preferred orientation. Furthermore, the accumulation of dislocations on the acicular α' and β phase interface led to fatigue crack initiation owing to stress concentration. In addition, the lager average Schmid factor and smaller deviation in WM of the joint at a large stress amplitude was owing to the smaller relative geometrical orientation. • The variable amplitude fatigue behavior of laser-welded Ti-6Al-4V joint was studied. • Differences in grain size and orientation lead to joint fracture in weld metal. • Dislocations accumulated on the phase interface are key elements leading fracture. • The characteristics of joint microstructure and fracture behavior are related. [ABSTRACT FROM AUTHOR]
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- 2023
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21. Robust horizontal-plane formation control for small fixed-wing UAVs.
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Chen, Jintao, Yang, Wenlong, Shi, Zongying, and Zhong, Yisheng
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CASCADE control , *AERODYNAMIC load , *FORMATION flying , *ADAPTIVE control systems , *CLOSED loop systems , *LINEAR systems , *DRONE aircraft , *HYPERSONIC planes - Abstract
The formation control problems of small fixed-wing(FW) unmanned aerial vehicles (UAVs) are investigated in this paper. By adopting a simplified aerodynamic force model and a cascade control structure, the horizontal motion of a FW UAV can be described as a linear system with uncertainties based on the feedback linearization technique. Thereafter, a novel robust formation protocol is proposed, which incorporates two components: the nominal controller and the robust filter-based compensator to restrain the influences of equivalent uncertainties. It turns out the formation error can converge to a sufficiently small neighborhood of the origin. The stability of the closed-loop system is proved in combination with classic Lyapunov-based arguments. Finally, field formation flight experiments on four small FW UAVs are carried out to demonstrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]
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- 2022
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22. Graphene layers produced from carbon nanotubes by friction
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Chen, Jintao, Chen, Liqing, Zhang, Zhaochun, Li, Jianlin, Wang, Lianjun, and Jiang, Wan
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GRAPHENE , *MULTIWALLED carbon nanotubes , *FRICTION , *SCANNING electron microscopy , *RAMAN spectroscopy , *OPTICAL reflection - Abstract
Abstract: Graphene layers have been produced from multi-walled carbon nanotube (MWCNT) bulk materials by friction when polished on ground-glass, offering a novel and effective method to produce graphene layers, which, more importantly, could be transferred to other substrates by rubbing. Field emission scanning electron microscopy, Raman spectroscopy, atomic force microscopy, transmission electron microscopy and selected area electron diffraction confirmed the formation of graphene layers. They were thought to be peeled away from the MWCNT walls due to friction. The reflection spectra showed that absorption of as-produced graphene layers decreased with wavelength in the range of 250–400nm, compared to the MWCNT bulk material having strong absorption at 350nm. Nanoscratch test was used to determine the mechanical properties of graphene films, suggesting the tolerance of as-produced graphene film to flaws introduced by scratch. [Copyright &y& Elsevier]
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- 2012
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23. Identification of Rickettsia spp., Anaplasma spp., and an Ehrlichia canis-like agent in Rhipicephalus microplus from Southwest and South-Central China.
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Lu, Miao, Tian, Junhua, Pan, Xingliang, Qin, Xincheng, Wang, Wen, Chen, Jintao, Guo, Wenping, and Li, Kun
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Rhipicephalus microplus is considered to be the most important tick infesting cattle, buffalo, horse, goats as well as other animals. They transmit diseases between domestic animals and act as vectors of a variety of zoonotic pathogens. Although pathogens harbored by R. microplus have been extensively studied, the Rickettsiales pathogens vectored by R. microplus in some areas of China remained largely unexplored. From August to October 2020, a total of 291 R. microplus ticks were collected from goats and cattle in three Southern China provinces, Guangxi (n = 138), Sichuan (n = 120) and Hubei (n = 33) provinces. Phylogenetic analysis based on COI gene sequences shows that these ticks are divided into three distinct clades, indicating the remarkable genetic diversity of R. microplus ticks in China. These samples were subsequently screened for the presence of Rickettsia, Anaplasma and Ehrlichia using conventional PCR and sequencing. Subsequently, five bacterial species were identified. Out of the 120 tick DNA samples from Sichuan province, 35.83% (43/120) were positive for Rickettsia sp. belonging to spotted fever group (SFG), 12.50% (15/120) were positive for Anaplasma marginale and 0.83% (1/120) was identified as A. platys. From the 138 DNA samples from Guangxi province, an Ehrlichia canis -like and Rickettsia sp. were detected, with a positive rate of 11.59% (16/138) and 2.17% (3/138), respectively. A. capra DNA was detected in 4 out of 33 (12.12%) samples from Hubei province. Notably, the 16S, gltA and groEL sequences of the E. canis -like are closely related to the E. canis strain previously identified from China, and form a distinct cluster in the phylogenetic trees. Collectively, our results expand the knowledge on tick-borne Rickettsiales pathogens in China. Because the state of engorgement of ticks was not recorded, it is not clear at this stage whether these pathogens are infecting the ticks or are simply present in the blood meal. Given the public health significance of SFG Rickettsia, A. capra, A. platys and E. canis , a thorough investigation of the diversity and presence of pathogens in R. microplus in areas with tick-associated diseases are needed. [ABSTRACT FROM AUTHOR]
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- 2022
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24. WDICD: A novel simulated dataset and structure-aware framework for semantic segmentation of spacecraft component.
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Huang, Kun, Zhang, Yan, Ma, Feifan, Chen, Jintao, Tan, Zhuangbin, and Qi, Yuanjie
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SOLAR panels , *COMPUTATIONAL complexity , *SPACE vehicles , *NAVIGATION , *LIGHTING - Abstract
The identification and localization of non-cooperative target, especially for the components such as solar panel and docking ring, is crucial for missions involving the on-orbit space services, navigation, and positioning. However, on-orbit spacecraft images are difficult to obtain, and it requires substantial effort to label them with pixel-wise accuracy for semantic segmentation. To address the above problems, we construct a simulated Wide-Depth Illumination-Composite Dataset (WDICD) and introduces an automatic pixel-level semantic annotation method. Furthermore, this paper proposes a structure-aware framework for semantic segmentation of spacecraft component, which introduces a boundary-aware auxiliary task and constructs a boundary-distance-aware contrast loss based on batch-wise grouping. The related boundary-aware tasks alleviate the prediction error of semantic segmentation near the boundary. Experimental results demonstrate that the proposed method achieves SOTA mIoU results in spacecraft component segmentation against complex backgrounds on two datasets. Particularly, the test results on spaceborne device show that the proposed framework balances precision and efficiency without generating additional computational complexity. • A simulated Wide-Depth Illumination Composite Dataset (WDICD) is introduced. • A structure-aware framework is proposed for spaceborne equipment. • A boundary-distance-aware contrast loss (BDL) is constructed. [ABSTRACT FROM AUTHOR]
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- 2024
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25. Skeleton-based coordinate system construction method for non-cooperative targets.
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Huang, Kun, Zhang, Yan, Chen, Jintao, Ma, Feifan, Tan, Zhuangbin, Xu, Zheyu, and Jiao, Zhongxing
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POINT cloud , *DATA visualization , *PROBLEM solving - Abstract
Due to the lack of structure and part information in non-cooperative targets, the task of pose estimation suffers from unstable and unreliable initial coordinate system. In this paper, we introduce a curve-skeleton-based method to construct the robust coordinate system automatically for non-cooperative targets. First, a nonmanifold-Laplacian-based method is proposed to extract the curve skeleton from point clouds. The proposed method solves the over-contraction problem while preserves the topology and structure of skeleton well during point clouds contraction. Additionally, we create the skeleton graph to detect the skeleton structure and key points automatically. Then, the detected skeleton feature is used to construct target coordinate system, and improve the stability and robustness. Specifically, a real-scan dataset is constructed in this paper, and the proposed point cloud contraction method outperforms previous methods in structural representation and visualization. The mean rotation error of proposed coordinate system construct method performs 0.1249° and 1.2135° in 0%–30% noise ratio of distortions and outliers, and performs 7.04° and 4.21° in real-scan aircraft and satellite datasets. The results in complete and incomplete datasets verify the robustness and reliability of our skeleton-based coordinate system. • We introduce the local contraction state and solve the over-shrinkage. • We construct the skeleton-based coordinate system for non-cooperative targets. [ABSTRACT FROM AUTHOR]
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- 2024
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26. Laser induced graphene based high-accurate temperature sensor with thermal meta-shell encirclement.
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Hou, Maoxiang, Wen, Guanhai, Chen, Jintao, Xie, Bin, Yan, Lu, Chen, Yun, and Chen, Xin
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ELECTRIC vehicles , *TEMPERATURE sensors , *GRAPHENE , *LASERS , *TEMPERATURE measurements - Abstract
• Applied Laser-induced graphene based thermal meta-shell encircled temperature sensor for the first time. • The sensor provided a high accuracy with a deviation of only 0.21 K and a fast response time of 1.15 s. • The sensor exhibits controllable thermal conductivity, insensitive to humidity and vibration, and low cross sensitive to bend. Accurate temperature measurement is critical in various fields, particularly in new energy vehicle power batteries and biomedicine. However, placing a temperature sensor in a thermal field can cause perturbations that lead to inaccuracies in measurement, which can have severe consequences. To address this issue, a Laser-induced graphene (LIG) based meta-shell encircled temperature sensor was proposed that takes advantage of the controllable thermal conductivity of LIG. The sensor's thermal measurement capabilities are theoretically analyzed, and the proposed approach is shown to eliminate thermal perturbations caused by the mismatch between the sensor and background, resulting in more accurate measurements. The effects of different laser processing parameters on the alteration and enhancement of LIG thermal conductivity have also been experimentally demonstrated for constructing the thermal meta-shell. The high-accuracy of the proposed sensor was experimentally verified by comparing the temperature differences with a bare sensor. The meta-shell encircled sensor showed a maximum thermal deviation of only 0.21 K, while the bare sensor produced a deviation of 1.55 K. Furthermore, the LIG-based sensor can maintain high accuracy in a high-temperature environment exceeding 410 K, and its stability and repeatability have been experimentally verified. The sensor also shows a fast response time of 1.15 s and can maintain accurate temperature measurement under large curvature (0.4 m−1), insensitive to humidity and vibration, proving its applicability in complex situations. The proposed LIG-based meta-shell encircled temperature sensor is manufactured through laser direct writing method and is easy to mass-produce, making it highly promising for high-accurate temperature monitoring applications. [ABSTRACT FROM AUTHOR]
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- 2023
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27. Experimental investigation of enhanced heat transfer in plate heat exchanger under heaving and yawing conditions.
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Hua, Dan, Zhang, Lizeen, Chen, Yi, Chen, Jintao, and Yao, Feng
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PLATE heat exchangers , *HEAT convection , *HEAT transfer coefficient , *WIND turbines , *COOLING systems - Abstract
An investigation into the heat transfer characteristics of plate heat exchangers operating within cooling systems of offshore floating wind turbines under marine sloshing conditions is presented herein. Utilizing a six-degree-of-freedom motion platform in conjunction with a plate heat exchanger performance testing setup, the effects of yawing and heaving motions, mass flow rates, sloshing amplitudes, frequencies, and intensities on the heat transfer characteristics of R134a plate heat exchangers were systematically explored. The Results indicate that both heaving and yawing significantly enhance the heat transfer performance, with heaving conditions showing a more pronounced effect. At a heaving amplitude of 100 mm and a frequency of 0.6 Hz, the convective heat transfer coefficient of R134a can be increased by up to 61.80 %. Heaving amplitude has a more substantial impact on heat transfer performance compared to yawing amplitude. The heat transfer correlation for R134a plate heat exchangers under yawing and heaving conditions has been presented, showing good predictive capabilities with deviations confined within ±15 %. • Heaving and yawing existence of the best operating point to optimize the heat transfer performance of the heat exchanger. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Control of intermetallic compounds in Ultrasonic-Assisted Sn soldering of Mg/Al alloys.
- Author
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Liu, Yingzong, Bai, Yujie, Chen, Jintao, Chen, Hui, Zhu, Zongtao, and Li, Yuanxing
- Subjects
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INTERMETALLIC compounds , *TIN , *SOLDER & soldering , *WELDING , *ALUMINUM alloys , *TIN alloys , *COPPER-tin alloys - Abstract
[Display omitted] • The Mg 2 Sn formation and growth was found mainly occurred during the cooling stage. • The Mg 2 Sn thickness was inhibited to less than 5 μm by using water-cooling. • The joint strength was improved greatly with water-cooling than that of air-cooling. • The fracture location changed from the IMC layer to the solder with water-cooling. Magnesium and aluminum alloys are widely used in various industries because of their light weight and other properties. However, Mg–Al intermetallic compounds (IMCs) decrease the joint properties of Mg/Al, which limits its applications. Here, the alloys AZ31 Mg and 6061 Al are soldered together with Sn and Sn–9Zn solders though different cooling rates via ultrasonic-assisted soldering to control IMC formation and growth. Results show that this prevents formation of Mg–Al IMCs such as Al 3 Mg 2 and Al 12 Mg 17 ; however, Mg 2 Sn forms in the soldered joints. The Mg 2 Sn thickness increases with soldering temperature, which reduces joint strength. The thickness is reduced using the Sn–9Zn solder, and the effect of Zn is analyzed. With the use of water-cooling, the Mg 2 Sn formation and growth are inhibited, the Mg 2 Sn thickness is kept below 5 μm, and the shear strength peaks at 53.2 MPa. A soldering model of Mg 2 Sn formation is proposed to reveal the evolution and inhibition mechanism of Mg 2 Sn. This study well controls IMC thickness and improves joint strength, thus expanding industrial application of Mg–Al dissimilar metals and providing a feasible method for controlling IMCs in dissimilar metal joining. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
29. Diagnosis and Management of Pediatric Papillary Craniopharyngiomas.
- Author
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Zhao, Chuan, Zhou, Zhongqing, Zhang, Yongli, Qi, Xueling, Wang, Xianlong, Lin, Da, Liu, Hongxing, Wang, Ye, Weng, Chaoqun, Chen, Jintao, Hu, Wenxin, Liao, Lianming, and Lin, Zhixiong
- Subjects
- *
DIAGNOSIS , *MAGNETIC resonance imaging , *SYMPTOMS , *CRANIOPHARYNGIOMA , *COMPUTED tomography , *DIAPHRAGM walls - Abstract
Papillary craniopharyngioma (PCP) was previously believed to occur only in adults. Sporadic pediatric PCP (PPCP) confirmed by detection of BRAF V600E mutation has been reported since 2018, but is often misdiagnosed before being diagnosed definitively. We aimed to evaluate PPCP characteristics and propose diagnostic criteria for prompt diagnosis, seeking to reduce patient morbidity and mortality and reduce costs linked to misdiagnosis. This study included 5 patients with PPCPs whose data were retrieved retrospectively from among 1032 patients with craniopharyngiomas admitted to Sanbo Brain Hospital Management Group from March 2017 to May 2021. Patients' demographics, clinical presentation, tumor imaging characteristics, histopathologic results, surgical approaches, and postoperative outcomes were analyzed. PPCP was misdiagnosed intraoperatively as sellar abscess (n = 4) or Rathke cleft cyst (n = 1). Preoperative magnetic resonance imaging showed that all tumors were under the saddle diaphragm, and the cyst wall was enhanced (n = 5). Computed tomography scans showed scattered high-density signs (n = 4). No recurrence was noted after complete resection. Postoperative hypothalamic dysfunction was mild. BRAF V600E mutation was confirmed in all cases by sequencing and immunohistochemistry. Immunohistochemistry showed granulation and inflammation and MPO, CD3, CD20, CD38, CD68, and CD163 were positively expressed. Misdiagnosis of PPCP is responsible for failed surgical treatment. We propose that prompt diagnosis of PPCP can be achieved if preoperative magnetic resonance images show the tumor under saddle diaphragm with tumor wall enhancement and computed tomography scans show high-density signs scattered in the tumor, which leads to safe, effective tumor resection. Our proposed diagnosis and treatment strategy for PPCP reduces morbidity and mortality. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Tailoring surface terminals on MXene enables high-efficiency electromagnetic absorption.
- Author
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Liu, Dong, Liu, Jimei, Li, Chong, Ji, Yanwen, Han, Yuxuan, Xue, Zhiwei, Lv, Quanyong, Chen, Jintao, Wang, Yongxiao, and Li, Hui
- Subjects
- *
ABSORPTION , *SURFACE chemistry , *LEWIS acids , *FUSED salts , *COLLOIDAL stability , *SURFACE conductivity , *POWDERS - Abstract
MXene (Ti 3 C 2 T x) is an important category of two-dimensional (2D) materials due to its distinctive metallic conductivity and adjustable surface chemistry. The exceptional benefits of heterointerface and defects or viods, combined with the distinct electromagnetic (EM) properties, inject boundless potential into the advancement of MXene-based absorbers for EM absorbing materials. However, conventional synthetic methods depend on chemical etching of MAX powders (Ti 3 AlC 2) using hazardous HF or similar substances, resulting in MXene sheets with fluorine termination and limited stability in colloidal dispersions under ambient conditions. Herein, varied synthetic routes were proposed to prepare MXenes with different terminal groups by the fluoride-based salts, fluoride-free molten salts, and alkali etching. 2D MXene nanosheets with abundant surface groups are excellent EM absorbing materials, and the MXene etched by the Lewis acid CuCl 2 delivered remarkable reflection loss (RL) value of −47.56 dB at 2.5 mm and broad bandwidth of 4.8 GHz due to promoted interfacial polarization. By conducting a thorough examination of the structural changes in MXenes, this study aims to propose a viable method for delaminating single-layer MXene and elucidate the EM absorption mechanisms. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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