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Influence of Blade Outlet Angle on Inner Flow Field of Centrifugal Pump Transporting Salt Aqueous Solution

Chinese Journal of Mechanical Engineering 2009年第6期22卷 912-917页

作者： YANG Minguan KANG Can dong xiang liu dong School of Energy and Power Engineering Jiangsu University Zhenjiang 212013 China

During transportation of salt aqueous solutions with centrifugal pump, crystallization phenomenon is frequently encountered. For this kind of two-phase flow, it is difficult to be accurately modeled since there are various medium properties and phase change characteristics. In view of experiment, several problems are hampering the implementation of precise measurement. Influences of blade outlet angle and medium temperature on crystallization rate were studied. Sodium sulfate solution was applied to simulate practical fluid in chemical industry. Particle image velocimetry（PIV） was employed to measure velocity distributions in rotating impeller. Crystallization processes in three impellers with different blade outlet angles were investigated. Relations among crystallization and flow parameters such as temperature and velocity were obtained. With the same blade wrap angle, when blade outlet angle is larger, diffusion of single flow passage gets stronger, relative velocity at blade outlet decreases and large scale vortex tends to appear near the blade working surface. For the impact of volume effect of particle phase on fluid viscosity, both liquid and solid phase velocities decrease with continual forming and growing of crystal particles. Velocity of solid phase is greater than that of liquid phase and its direction leans more closely to blade working surface. Solid particles tend to move towards blade working surface, as is more obvious in the impeller with large blade outlet angle. Therefore, collision between solid particles with stem part of blade working surface is more intensive in impeller with large blade outlet angle. Concerning transportation of salt aqueous solution, accurate PIV measurement is conducted in centrifugal impellers with different blade outlet angles. The results are useful and instructive in relevant engineering design and operation.

关键词： centrifugal pump flow with crystallization blade outlet angle particle image velocimetry(PIV)

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Moments of the maximum of normed partial sums of ρ^--mixing random variables

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Applied Mathematics(A Journal of Chinese Universities) 2009年第3期24卷 355-360页

作者： liu xiang-dong liu Jin-xia Dept. of Statist. Jinan Univ. Guangzhou 510630 China

Let {Xn,n ≥ 1} be a sequence of identically distributed ρ^--mixing random variables and set Sn =∑i^n=1 Xi,n ≥ 1,the suffcient and necessary conditions for the existence of moments of supn≥1 ｜Sn/n^1/r｜^p（0 〈 r... 详细信息

关键词： moment of supremum of normed partial sum ρ^--mixing random variable

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High temperature determines the ups and downs of small brown planthopper Laodelphax striatellus population

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Insect Science 2013年第3期20卷 385-392页

作者： xiang-dong liu Ai-Min Zhang Department of Entomology Nanjing Agricultural University Nanjing China

Small brown planthopper, Laodelphax striatellus （Fall6n） numbers usually drop sharply in the summer and revive quickly in the autumn. However, it is unclear whether and how the high temperature plays a role in this process. The effects of durations of heat exposure （33~C） on life-history traits were examined here. Exposure of adults for 1 day during the oviposition stage led to a very low survival of nymphs. The average longevity ofL. striatellus exposed for 1-31 days from oviposition was significantly longer than that of the control （27℃）. Short-term （1-5 days） heat exposure of the third instar nymphs did not significantly influence eclosion, but exposure of the fourth instar nymphs significantly increased eclosion. Lifespan from egg to adult was significantly lengthened when the third instar nymphs were exposed to heat for 2-15 days, or the fourth instar were exposed for 10 days. The preoviposition period was prolonged by heat exposure of the third or fourth instar nymphs. Short-term heat exposure of less than 3 days of the third or fourth instar nymphs did not restrict fecundity, but when the exposure duration exceeded 5 days the total eggs per female and hatchability decreased. Exposure to high temperature increased the brachypter rate of adults. In summary, low survival and slowing development under heat exposure resulted in population decline in the summer, and the relatively high fecundity and brachypter rate led to quick revival in autumn. Temperature in the summer determines the rise and fall in numbers ofL. striatellus.

关键词： development fecundity heat exposure Laodelphax striatellus wing form

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Extension of the rotating dipole model with oblateness of both primaries

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Research in Astronomy and Astrophysics 2017年第1期17卷 11-20页

作者： xiang-Yuan Zeng xiang-dong liu Jun-Feng Li School of Automation Beijing Institute of Technology School of Aerospace Engineering Tsinghua University

A rotating mass dipole can be used to understand the dynamical behaviors around elongated asteroids as well as binary asteroids. In this paper an improved dipole model with oblateness in both primaries is investigated. The dynamical equations of a particle around the improved model are first derived by introducing the oblateness coefficients. The characteristic equations of equilibrium points are obtained, resulting in the emergence of new equilibria in the equatorial plane and the plane xoz de- pending on the shape of the spheroid. Numerical simulations are performed to illustrate the distribution of these equilibrium points. Significant influence from the oblateness of the primaries on the topological structure is also analyzed via zero-velocity curves.

关键词： celestial mechanics - minor planets, asteroids general - methods numerical

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*** Rate and L^(p)-Convergence of Bisexual Branching Processes in a Random Environment and Varying Environment

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Acta Mathematicae Applicatae Sinica 2023年第2期39卷 337-353页

作者： Sheng XIAO xiang-dong liu Ying-qiu LI School of economics Jinan UniversityGuangzhou510632China School of Mathematics and Statistics Changsha University of Science and TechnologyChangsha 410004China Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science and TechnologyChangsha 410004China

Let(Z_(n))be a supercritical bisexual branching process in a random environmentξ.We study the almost sure(a.s.)convergence rate of the submartingale W_(n)=Z_(n)/In to its limit W,where(In)is an usually used norming *** prove that under a moment condition of order p∈(1,2),W-W_(n)=o(e^(-na))*** some a>0 that we find explicitly;assuming the logarithmic moment condition holds,we haveW-W_(n)=o(n^(-α))a.s..In order to obtain these results,we provide the L^(p)-convergence of(W_(n));similar conclusions hold for a bisexual branching process in a varying environment.

关键词： bisexual branching process convergence rate varying environment random environment

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Relative contribution of genetic and environmental factors to determination of wing morphs of the brown planthopper Nilaparvatalugens

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Insect Science 2023年第1期30卷 208-220页

作者： Chao Zhang Meng-Sha Mao xiang-dong liu Department of Entomology Nanjing Agricultural UniversityNanjingChina

Wing dimorphism is a fascinating feature of the ability of insects to adapt to *** brown planthopper(BPH)Nilaparvata lugens,a serious pest of rice,can switch between the long-and short-winged *** has been known that environmental factors can affect the wing morph of ***,it is still unclear whether the effect of environment is dependent on BPH genetic backgrounds or *** the present study,we established the pure-bred lineages of short-and long-winged BPHs via multigenerational selection,and we found that survival and fecundity were similar between these 2 *** morphs of the pure-bred lineages were almost fully dependent on genetics,but independent of the environmental factors,nymphal density and rice plant stage,2 key factors affecting BPH wing *** the unselected BPH population,short-and longwinged morphs were produced depending on those 2 environmental factors,indicating the contribution of environment to wing *** the wing-selected lineages,4 developmental regulated genes of wing,NllnRI,NllnR2,NIAkt,and NIFoxo were expressed stably in the short-winged adults,but almost silenced in the long-winged ***,all these genes were expressed normally with a similar level in both the short-and long-winged adults in an unselected population except *** pure-bred lineages of long-and short-winged morphs exhibited different expression patterns of wing development-regulated genes,suggesting the genetic determination of wing *** of environmental factors on wing morphs occurred only in the genetic mix population.

关键词： environmental effect gene expression genetic determination Nilaparvata lugens pure-bred lineage wing dimorphism

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How does the host-specialized aphid deal with food deficiency？

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Insect Science 2014年第3期21卷 334-341页

作者： Ting-Ting Xu Ting-Ting Ma xiang-dong liu Department of Entomology Nanjing Agricultural University Nanjing China

Aphis gossypii Glover shows obvious host specialization, with cucurbit- and cotton-specialized biotypes or host races in many regions. Because its annual natal hostcrops senesce earlier the cucurbit-specialized biotype may suffer food deficiency. The method this biotype uses to overcome this challenge is still poorly understood. In orderto understand the potential of the cucurbit-specialized biotype aphids in host shift and usage, the performance of this biotype on cotton （Gossypium hirsutum）, a common butpoor quality host plant, was explored in this study. The cucurbit-specialized aphids could establish populations on cotton only when these plants had at least nine leaves, and subsequent populations developed rather slowly. The presence of whitefly populations on cotton improved the success rate of cucurbit-specialized aphids. The cucurbit-specialized aphidswere mainly distributed on the older leaves of cotton, with only a few settling on the upper leaves. The cucurbit-specialized aphids reared on cotton for 40, 54 and 61 days stillmaintained strong preference for their natal host plant, cucumber （Cucumis sativus）, rather than cotton, and their net reproductive rates and intrinsic rates of natural increase weredramatically lower when they were transferred onto new six-leaf cotton plants or detached leaves. Therefore, we concluded that the cucurbit-specialized aphids have the potentialto utilize mature or whitefly-stressed cotton plants, but that this feeding experience on cotton did not alter their specialization for cucurbits. Some cotton plants could act as atemporary host for the cucurbit-specialized aphids to overcome food deficiency arising from senescing cucurbits.

关键词： Aphidgossypii cotton-melon aphid host shift host specialization temporary host whitefly-stressed cotton

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Lattice Boltzmann model for interface capturing of multiphase flows based on Allen–Cahn equation

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Chinese Physics B 2022年第2期31卷 444-452页

作者： He Wang Fang-Bao Tian xiang-dong liu Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China School of Engineering and Information Technology University of New South WalesCanberraACT 2600Australia College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhou 225127China

A phase-field-based lattice Boltzmann model is proposed for the interface capturing of multi-phase flows based on the conservative Allen–Cahn equation(ACE).By adopting the improved form of a relaxation matrix and an equilibrium distribution function,the time derivative?t(φ)induced by recovering the diffusion term in ACE is *** conducted Chapman–Enskog analysis demonstrates that the correct conservative ACE is *** benchmark cases including Zalesak’s disk rotation,vortex droplet,droplet impact on thin film,and Rayleigh–Taylor instability are investigated to validate the proposed *** numerical results indicate that the proposed model can accurately describe the complex interface deformation.

关键词： lattice Boltzmann method phase field multiphase flow

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Preparation and Characterization of UV-absorbing PVDF Membranes via Pre-irradiation Induced Graft Polymerization

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Chinese Journal of Polymer Science 2019年第5期37卷 493-499页

作者： Li dong xiang-dong liu Zheng-Rong Xiong De-Kun Sheng Yan Zhou Yu-Ming Yang Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Science and Technology of China

Herein, excellent UV-absorbing poly(vinylidene fluoride)(PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with ^(60)Co γ-ray were modified with the polymerizable UV absorber 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2 H-benzotriazole(RUVA-93). The influences of irradiation dose and monomer concentration on the prepared PVDF-g-PRUVA-93 membranes were investigated, and the optimal condition was eventually obtained. The chemical structures of the films were studied by ~1H-NMR, FTIR, and XRD. UV light transmittance and DSC tests were used to characterize the UV-absorbing performance and thermal property of the PVDF films before and after modification. The results proved that the PRUVA-93 side chains were successfully incorporated into the PVDF main chains and the obtained PVDF-g-PRUVA-93 films possessed remarkable UV-absorbing property. The modified membrane made under the optimized experiment condition could completely block the UV light in the range of 200-387 nm. Additionally, the transmittance of the PVDF-g-PRUVA-93 film could be reduced to0.04% in 280-320 nm, where the light irradiation could damage polymer materials most seriously.

关键词： PVDF membrane Modification Irradiation Grafting UV-absorbing

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Macular laser photocoagulation with or without intravitreal triamcinolone pretreatment for diabetic macular edema： a result from five randomized controlled trials

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International Journal of Ophthalmology(English edition) 2016年第1期9卷 132-138页

作者： xiang-dong liu Xiao-dong Zhou Zhi Wang Yong-Ming Shen Department of Ophthalmology Affiliated Jinshan HospitalFudan University Shanghai 201508 China

AIM：To assess possible benefits of intravitreal triamcinolone acetonide（IVTA）injection as pretreatment for macular laser photocoagulation（MLP）in patients with diabetic macular edema（DME）.·METHODS：Published randomized controlled trials（RCTs）concerning MLP with or without IVTA pretreatment for DME were retrieved from databases CNKI,Medline,EMbase,Web of Science,and the Cochrane Library.A Meta-analysis on eligible studies was conducted using Rev Man 5.0 *** investigators independently assessed the quality of the trials and extracted *** outcome measures included the change in best-corrected visual acuity（BCVA）,difference in central macular thickness（CMT）and adverse events reporting in particular elevated intraocular pressure within the follow-up *** results were pooled using weight mean difference（WMD）or odds risk（OR）with their corresponding 95%confidence intervals（CI）.A fixed-or random-effect model was employed depending on the heterogeneity of the inclusion trials.·R ESULTS：Finally,five independent RCTs were identified and used for comparing MLP with IVTA pretreatment（131 eyes）with MLP alone（133 eyes,control group）.The overall study quality was relatively higher according to the modified Jadad *** Metaanalysis showed that MLP with IVTA pretreatment significantly reduced CMT at one,three and six months（=0.002,0.0003 and 0.04,respectively）,compared with MLP *** IVTA pretreatment group showed statistically significant improvements in BCVA at the one-month follow up as compared with the control group（=0.03）.At three-and six-month follow up,there was a beneficial trend towards improving visual acuity in the IVTA pretreatment group without statistical significance between groups（=0.06 and 0.20,respectively）.The incidence of elevation of intraocular pressure was significantly higher in the IVTA pretreatment group than in the control group（〈0.0001）.No evidence of publication bias was present according to Begg’s test and Egger’s *** wa

关键词： photocoagulation intravitreal injection triamcinolone acetonide diabetic macular edema

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