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Numerical analysis of a ventilated supercavity under periodic motion of the cavitator

Journal of Hydrodynamics 2021年第6期33卷 1216-1229页

作者： Yun-hua jiang Zhi-hui Zou jia Li Yao Yao Le-le Yang School of Ocean Engineering and Technology Sun Yat-sen UniversityGuangzhou 510275China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Department of Aerospace Engineering Harbin Engineering UniversityHarbin 150001China AVICJonhon Optronic Technology Co. Ltd.Luoyang 471003China

This paper presents a numerical simulation of the geometry and the pressure distribution of a ventilated supercavity at different cavitator amplitudes and periods of *** numerical method is validated by comparing with the results of a semi-empirical formula under specific *** is shown that the simulation can capture the boundary fluctuations of the ventilated supercavity and its internal pressure variations in a cavitator motion *** simulation results show that the supercavity boundary experiences wave-like deformations when the wavelength of the disturbance caused by the cavitator motion is comparable to the supercavity *** is also shown that the supercavity closure changes in form between a re-entrant jet and a twin vortex owing to the variations of the pressure difference between the outside and the inside of the supercavity near the closure *** maximum diameter of the ventilated supercavity exhibits periodic changes with a double peak in each cavitator motion cycle,caused by the corresponding changes of the difference between the internal and external *** the increase of the amplitude of motion of the cavitator,the supercavity boundary has enhanced wave-like undulations,with an increased maximum diameter,and with fluctuations in the cavitation *** the period of the cavitator motion increases,the wavelength of the disturbances caused by this motion becomes greater than the supercavity length,and so the wave-like undulations of the supercavity boundary and the maximum diameter of the supercavity gradually decrease,but the variations of the cavitation number ***,with the increase of the periods,the delay effects on the variations of the characteristics of the supercavity geometry caused by cavitator motion gradually decrease,and they practically vanish for large periods.

关键词： Ventilated supercavity geometrical and pressure characteristics cavitator motion

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Multi-stage penetration characteristics of thick ultra-high molecular weight polyethylene laminates

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Defence Technology（防务技术） 2023年第9期27卷 101-110页

作者： Ming-jin Cao Li Chen Rong-zheng Xu Si-jia Liu Qin Fang Engineering Research Center of Safety and Protection of Explosion&Impact of Ministry of Education Southeast UniversityNanjing211189China Institute of Architectural Engineering Huanghuai UniversityZhumadian463000China State Key Laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China

To further reveal the failure mechanisms of thick ultra-high molecular weight polyethylene(UHMWPE)laminates,field firing tests were conducted for 10-,20-,and 30-mm thick laminates against 12.7-mm calibre wedge-shaped fragment simulated projectiles at high velocities between 450 and 1200 m/*** ballistic performance,deformation process,and staged failure characteristics of the laminates with different thicknesses were compared and *** results demonstrate that the ballistic limits of the UHMWPE laminates increase almost linearly with laminate *** 10-mm thick laminate generally experiences two-stage failure characteristics,whereas three-staged failure occurs in the 20-and 30-mm thick laminates and the progressive delamination is *** energy limit concept representing the maximum energy absorption efficiency and the idea of reuse of the thick UHMWPE laminates are proposed in this *** findings of this research will be useful in the design of flexible and effective UHMWPE-based protective equipment.

关键词： UHMWPE laminates Ballistic limit Thickness Mechanism Energy limit

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CFD simulation of flow and mixing characteristics in a stirred tank agitated by improved disc turbines

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Chinese Journal of Chemical Engineering 2022年第10期50卷 95-107页

作者： Zhuotai jia Lele Xu Xiaoxia Duan Zai-Sha Mao Qinghua Zhang Chao Yang CAS Key Laboratory of Green Process and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China School of Chemical Engineering Nanjing Tech UniversityNanjing 211816China

To reduce the power consumption and improve the mixing performance in stirred tanks,two improved disc turbines namely swept-back parabolic disc turbine(SPDT)and staggered fan-shaped parabolic disc turbine(SFPDT)are *** validation of computational fluid dynamics(CFD)model with experimental results,CFD simulations are carried out to study the flow pattern,mean velocity,power consumption,pumping capacity and mixing efficiency of the improved and traditional impellers in a dished-bottom tank under turbulent flow conditions,The results indicate that compared with the commonly used parabolic disc turbine(PDT),the power number of proposed SPDT and SFPDT impellers is reduced by 43%and 12%,and the pumping efficiency is increased by 68%and 13%,***,under the same power consumption(0-700 W·m^(-3)),the mixing performance of both SPDT and SFPDT is also superior to that of Rushton turbine and PDT.

关键词： Flow regime Mixing time Stirred vessel Computational fluiddynamics Improved discturbine

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Mimicking peroxidase active site microenvironment by functionalized graphene quantum dots

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Nano Research 2020年第5期13卷 1427-1433页

作者： Qi Xin Xinrui jia Asmat Nawaz Wenjing Xie Litao Li jian Ru Gong CAS Center of Excellence for Nanoscience CAS Key Laboratory for Nanosystem&Hierarchical FabricationNational Center for Nanoscience and Technology11 Beiyitiao ZhongguancunBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Orthopaedics the 309th Hospital of the PLABeijing 100091China

The development of high-efficiency peroxidase mimetics is highly desirable in view of high cost and low stability of natural *** the perspective of mimicking active site microenvironment at low cost,we herein report a novel histidine-functionalized graphene quantum dot(His-GQD)/hemin complex,which exhibits the highest catalytic rate for the peroxidase-based chromogenic reaction among the hemin-containing mimetics reported so ***,our peroxidase mimetic shows excellent tolerance to strongly acidic conditions and can function in a wide temperature ***-Burk plots and comprehensive electron paramagnetic resonance analysis reveal a ping-pong type catalytic mechanism for this *** addition,His-GQD/hemin demonstrates high efficiency and accuracy in detecting H2O2 and blood *** work provides an effective design of artificial enzymes for practical applications.

关键词： nanoenzyme graphene quantum dot heme active site peroxidase mimetic enzymatic microenvironment

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Assessing inflammation in Chinese subjects with subtypes of heart failure: an observational study of the Chinese PLA Hospital heart Failure Registry

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Journal of Geriatric Cardiology 2019年第4期16卷 313-319页

作者： Bo-Han LIU Yan-Guang LI Ji-Xuan LIU Xiao-Jing ZHAO Qia jia Chun-Lei LIU Zhen-Guo XU Kun-Lun he Beijing Key Laboratory of Chronic heart Failure Precision Medicine Chinese PLA General HospitalBeijingChina Department of Cardiology Chinese PLA General HospitalBeijingChina

Background Inflammation is an important element of the pathophysiological process of heart failure (HF) and is correlated with subtypes of HF. The association between multiple biomarkers of inflammation and HF subtypes in Chinese subjects remains unclear. This study aimed to compare the differences in inflammation biomarkers among Chinese patients with different subtypes of HF who have been identified to date. Methods We included 413 consecutive patients with HF,including 262 with preserved ejection fraction (HFpEF),55 with middle-ranged ejection fraction (HFmrEF) and 96 with reduced ejection fraction (HFrEF). Ten inflammation biomarkers were analyzed and compared according to the HF subtypes. One hundred contemporary non-HF subjects were also recruited as the control group. Moreover,the correlations between the inflammatory biomarkers and left ventricular ejection fraction of the HF subtypes were assessed. Results The mean age of the HF patients was 65.0 ± 12.0 years,65.8% were male. Distinct subtypes of HF demonstrated different inflammation biomarker panels. IL-6,PTX-3,ANGPTL-4 and TNF-α were correlated with HFrEF;IL-1β and PTX-3 were correlated with HFmrEF;and IL-1β and IL-6 were correlated with HFpEF. The multivariable logistic regression showed that IL-1β[relative ratio (RR)= 1.08,95% CI: 1.02–1.15,P = 0.010],IL-6 (RR = 1.03,95% CI: 1.01–1.06,P = 0.016),PTX-3 (RR = 1.31,95% CI: 1.11–1.55,P = 0.001),and ANGPTL-4 (RR = 1.05,95% CI: 1.02–1.07,P he HF subtype. Conclusions Diverse inflammation biomarkers have multifaceted presentations according to the subtype of HF,which may illustrate the diverse mechanisms of inflammation in Chinese HF patients. IL-6,PTX-3,and ANGPTL-4 were independent inflammation factors associated with HFrEF and H

关键词： Biomarkers Chinese patients Correlation heart failure Inflammation

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Characteristics of snow cover distribution along railway subgrade and the protective effect of snow fences

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Journal of Arid Land 2023年第8期15卷 901-919页

作者： LEI jia CheNG jianjun GAO Li MA Benteng AN Yuanfeng DONG Hongguang College of Water Conservancy&Architectural Engineering Shihezi UniversityShihezi 832003China

Railways built in cold,snowy,and lightly populated areas are subjected to wind and snow *** this study,we selected a snow hazard prevention and control section of the Altay–Zhundong Railway in Xinjiang Uygur Autonomous Region of China as the research *** investigated the deposited snowfall variation characteristics on the two sides and in the embankment pavement area of snow fences with different porosities,fence heights,and arrangement distances using single-factor tests and orthogonal tests based on global atmospheric reanalysis climate data,field survey data,and a multi-phase flow analysis *** results showed significant differences in the characteristics of snow cover distribution and snow cover thickness between the embankment and the cutting in the absence of snow protection *** maximum snow cover thickness of the embankment pavement decreased by 12.6%relative to the cutting *** snow cover thickness of the embankment exhibited an increasing trend from windward shoulder to leeward shoulder,whereas the snow cover thickness of the cutting presented a declining trend from windward shoulder to leeward *** the collaborative prevention and control of snow fences and embankments,the three factors can be ranked in terms of their sensitivity to deposited snowfall within the influence scope of snow fences as follows:fence height>arrangement distance>*** the same time,fence height yielded a significant relationship for the influence scope of snow fences(Phe three factors can also be ranked in terms of their sensitivity to deposited snowfall on the pavement as follows:porosity>fence height>arrangement *** the embankment protection of the Altay–Zhundong Railway against wind and snow,snow fence with a porosity of 75%,a fence height of 4.8 m,and an arrangement distance from the embankment of 60 m produced the best snow control *** revealing the characteristics of snow cover distribution along railway subg

关键词： snowdrift numerical simulation orthogonal test porosity fence height arrangement distance Altay-Zhundong Railway

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Electron force-induced dislocations annihilation and regeneration of a superalloy through electrical in-situ transmission electron microscopy observations

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Journal of Materials Science & Technology 2020年第1期36卷 79-83页

作者： Xina Zhang Hongwei Li Mei Zhan Zebang Zheng jia Gao Guangda Shao State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi'an 710072China

What effect does electric current do on dislocation evolution of metals keeps being a confusing question to be answered and proved. To this end, the dislocation evolution of a superalloy with electric current was directly observed by electrical in-situ transmission electron microscopy in this work. Dislocations annihilation at first and then regeneration was found for the first time, which directly proves the existence of electron force during the electrically-assisted manufacturing. Dislocations regeneration would be driven by the electron force and the resistance softening by the local Joule heating effect. Resultantly,a base could be provided for future electrically-assisted research.

关键词： Electron force Electrical in-situ TEM Local Joule heating effect Dislocation structure evolution

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Up-Conversion Photostimulated Luminescence of Mg_(2)SnO_(4) for Optical Storage

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Chinese Physics Letters 2011年第2期28卷 197-199页

作者： ZHANG jia-Chi QIN Qing-Song YU Ming-Hui SUN jia-Yao SHI Liu-Rong MA Xin-Long College of Physical Science and Technology Lanzhou UniversityLanzhou 730000

We report the first observation of up-conversion photostimulated luminescence in non-doped Mg_(2)SnO_(4).Stimulated by 980 nm infrared laser(reading)after ultraviolet irradiation(writing),the phosphor shows photostimulated emission band covering 470-550nm,which is due to the recombination of F centers with *** ceasing ultraviolet irradiation,the storage intensity would rapidly decrease to 59%of its original storage intensity in 2.5h and then would not degrade *** is suggested that the Mg_(2)SnO_(4)has potential applications for optical ***,the possible photostimulated luminescence mechanisms of Mg_(2)SnO_(4)are proposed.

关键词： ultraviolet luminescence centers

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Special Unipotent Representations of Simple Linear Lie Groups of Type A

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Acta Mathematica Sinica,English Series 2024年第3期40卷 707-716页

作者： Dan BARBASCH jia Jun MA Bin Yong SUN Chen Bo ZHU Department of Mathematics Cornell UniversityIthacaNY 14853USA School of Mathematical Sciences Xiamen UniversityXiamen 361005P.R.China Department of Mathematics Xiamen University Malaysia CampusSepangSelangor Darul Ehsan43900Malaysia Institute for Advanced Study in Mathematics&New Cornerstone Science Laboratory Zhejiang UniversityHangzhou 310058P.R.China Department of Mathematics National University of Singapore10 Lower Kent Ridge RoadSingapore 119076

Let G be a special linear group over the real,the complex or the quaternion,or a special unitary *** this note,we determine all special unipotent representations of G in the sense of Arthur and Barbasch-Vogan,and show... 详细信息

关键词： Special unipotent representations unitary representations coherent continuation Weyl group representations

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Carbon nanotube enhanced water-based drilling fluid for high temperature and high salinity deep resource development

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Petroleum Science 2022年第2期19卷 916-926页

作者： Jing-Ping Liu Xian-Fa Zhang Wen-Chao Zhang Kai-he Lv Yin-Rui Bai Jin-Tang Wang Xian-Bin Huang jia-Feng Jin Jin-Sheng Sun College of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China CNPC Engineering Technology R&D Company Limited Beijing 102206China

Drilling fluids face failure during drilling deep reservoir with high temperature and high *** experimental results show that high temperature and salinity reduce the negative charge on the surface of bentonite in the drilling fluid and cause the coalescence of bentonite *** a result,the particles coalesce,the grid structure is destroyed,and the rheological properties,rock-carrying capacity and filtration properties are *** resolve the foregoing,in this study,0.05-wt%carbon nanotubes are introduced into a 4%bentonite drilling fluid under conditions where the temperature and concentration of added Na Cl reach 180°C and 10 wt%,*** carbon nanotubes adsorb on the bentonite surface and increase the space among bentonite *** steric hindrance prevents the coalescence of bentonite in high temperature and high salt *** bentonite maintains the small size distribution of bentonite and supports the bentonite grid structure in the drilling *** a result,the rock-carrying capacity of the drilling fluid increases by 85.1%.Moreover,the mud cake formed by the accumulation of small-sized bentonite particles is dense;consequently,the filtration of bentonite drilling fluid reduced by 30.2%.

关键词： High temperature Water-based drilling fluid High salinity Carbon nanotube Deep resources

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