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Numerical Investigations on Effects of Physical Parameters on Single Bubble Generation from Capillary Needles in Newtonian Liquids

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Frontiers in Heat and Mass Transfer 2023年第1期21卷 337-366页

作者： meng jia Mingjun Pang School of Mechanical Engineering and Rail Transit Changzhou UniversityChangzhou213164China

The interphase mass,heat transfer efficiency,and flow resistance are strongly dependent on bubble size in gas-liquid two-phase systems,so it is very important for engineering applications to effectively control bubble *** this paper,the formation,growth,and detachment of single bubbles in Newtonian liquids based on capillary needles were studied in detail using a volume of fluid *** authors investigated the effects of gas injection velocity,gravitational level,surface tension coefficient,needle radius,and liquid-phase properties(liquid viscosity and density)on the process of bubble generation,and the effects of the above factors on bubble shape,detachment diameter,and time were *** results show that an increase in gas injection rate,liquid-phase viscosity,needle radius,and surface tension coefficient can lead to an increase in bubble detachment diameter;however,an increase in liquid-phase density and gravitational level can lead to a decrease in bubble detachment *** is found that the effect of the liquid-phase viscosity on bubble detachment diameter and time is slight,but the effect of gravitational level on detachment diameter and time is *** all the forces,buoyancy,surface tension,and pressure are the most important ones that control the generation of bubbles.

关键词： Bubble generation detachment diameter capillary needles VOF

A study on the catalytic performance of carbide slag in transesterification and the calculation of kinetic parameters

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Science China(Technological Sciences) 2015年第2期58卷 258-265页

作者： LIU meng Qi NIU Sheng Li LU Chun Mei LI Hui HUO meng jia School of Energy and Power Engineering Shandong University

The catalytic performance of carbide slag in transesterification is investigated and the reaction kinetic parameters are calculated. After being activated at 650℃, calcium compounds of carbonate and hydroxide in the carbide slag are mainly transformed into calcium oxide. The activated carbide slag utilized as the transesterification catalyst is characterized by X-ray diffraction （XRD）, attenuated total reflectance-Fourier transform infrared spectroscopy （ATR-FTIR）, nitrogen adsorption-desorption and the Hammett indicator method. Compared with the carbide slag activated at 700 and 800℃, the largest surface area of 22.63 m2g^-1, the smallest particle size of 265.12 nm and the highest catalytic efficiency of the carbide slag activated at 650℃ guarantee its capacity in catalyzing transesterification. Then, the influences of activated temperature （Ta）, molar ratio of methanol to oil （γ）, catalyst added amount （ζ）, reaction temperature （Tr） and reaction time （τ） on the catalytic performance are investi- gated. Under the optimal transesterification condition of Ta=650℃, γ=15, ζ=3%, Tr=60℃ and τ=-110 rain, the catalytic efficiency of 92.98% can be achieved. Finally, the kinetic parameters of transesterification catalyzed by the activated carbide slag are calculated, where activation energy （E） is 68.45 kJ mol^-1 and pre-exponential factor （k0） is 1.75×10^9 min^-1. The activated carbide slag shows better reused property than calcium hydroxide.

关键词： transesterification catalyst carbide slag kinetic parameters

Experimental study of a micro-scale solar organic Rankine cycle system based on compound cylindrical Fresnel lens solar concentrator

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Science China(Technological Sciences) 2019年第12期62卷 2184-2194页

作者： meng jia SONG PanPan WEI MingShan TIAN GuoHong ZHAO meng ZHENG HongFei HU GuangDa School of Mechanical Engineering Bejing Institute of TechnologyBeijing 100081China Department of Mechanical Engineering Sciences University of SurreyGuildford GU27HXUK

In the present study, a micro-scale solar organic Rankine cycle power generation system was developed. The system comprises of a solar collection system based on compound cylindrical Fresnel lens concentrator and an organic Rankine cycle power generation system integrated with a scroll expander. YD320 and R245 fa were used as the heat transfer fluid and the working fluid, respectively. The effects of the evaporation pressure, the degree of superheat, and the mass flow rate of the working fluid were analyzed to evaluate the solar collection efficiency, the electric power output, the thermal efficiency and exergy efficiency of the system. The results illustrate that both the increasing evaporation pressure and decreasing superheat degree have positive impacts on solar collection efficiency. The electric power increases as the evaporation pressure increases, while the thermal efficiency and the exergy efficiency decrease. However, the system overall efficiency decreases slowly due to the increase of solar collection efficiency. The electric power increases with the increment of the working fluid mass flow rate. The increasing mass flow rate has no visible impact on the thermal and exergy efficiencies of organic Rankine cycle subsystem, whereas a slightly increase of the thermal and exergy efficiencies of the integrated system. The electric power decreases with the increase of the superheat degree, whereas the thermal and the exergy efficiencies of the system increase. The system works more suitably with a higher degree of superheat for the small mass flow rate condition.

关键词： micro-scale SORC cylindrical Fresnel lens concentrator solar collection efficiency overall performance

An encapsulated optical microsphere sensor for ultrasound detection and photoacoustic imaging

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Science China(Physics,Mechanics & Astronomy) 2022年第2期65卷 44-49页

作者： jialve Sun jia-Wei meng Shui-Jing Tang Changhui Li Department of Biomedical Engineering College of EngineeringPeking UniversityBeijing 100871China ~State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter School of PhysicsPeking UniversityBeijing 100871China College of Future Technology Peking UniversityBeijing 100871

Optical whispering-gallery microresonators have attracted considerable interest for ultrasensitive ultrasound detection and photoacoustic imaging because of the combination of high quality factors and small cavity *** the last decade,ultrasonic sensors with on-chip microcavities have been extensively developed;however,they are unsuitable for the near-field photoacoustic microscopy of micro/nanoscale objects in complex biological environments and endoscopic *** this work,we developed ultrasonic sensors using two types of encapsulated microsphere resonators with different cavity materials.A noise equivalent pressure of as low as 160 Pa at 20 MHz was achieved with the acoustic response up to 70 MHz at-6 d ***,the microsensor was used for photoacoustic microscopy in which we successfully performed 3 D imaging of hairs and leaf *** microsphere ultrasonic sensor has considerable potential as a probe-type ultrasonic detector for near-field photoacoustic microscopy of micro/nanoscale objects such as subcellular structures and high-resolution endoscopic photoacoustic imaging with its high sensitivity and wide bandwidth.

关键词： optical whispering gallery micro-resonators ultrasound sensing photoacoustic imaging

Dispersion characteristics of seabed Scholte waves with variable velocity seawater in deep water

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Applied Geophysics 2022年第4期19卷 537-552,604页

作者： jiang jia-meng Yu Peng-Fei College of Oceanography Hohai UniversityNanjing 210024China

Acoustic velocity varies in deep-water *** obtain accurate inversion interpretations,it is necessary to develop a horizontally layered seawater–seabed(HLSS)model with continuously varying *** this work,we used an HLSS model based on wave theory to deduce the Scholte wave dispersion equations and established an HLSS model based on the acoustic velocity profile and the submarine medium parameters of the South China *** studied the dispersion characteristics of Scholte waves and theoretically calculated the amplitude–depth *** also examined the influence of deep-water environments on the dispersion characteristics of Scholte *** the real geological parameters of the Dongsha Islands in the South China Sea,we exploited the spectral element method to simulate seismic wave propagation in the fluid–solid interface and extracted the Scholte wave dispersion curves using multichannel analysis of surface waves(MASW).The consistent theoretical and extracted dispersion curve results verified the accuracy of our *** experiments showed that the dispersion characteristics of Scholte waves in deep water are weaker than those in shallow *** addition to the seawater depth and the physical parameters of seabed sediments,the seawater’s variable velocity also influences Scholte wave dispersion characteristics.

关键词： Scholte waves variable-velocity seawater dispersion characteristics amplitudedepth distribution.

Ganodermalucidum polysaccharide peptides attenuate post myocardial infarction fibrosis through down-regulating TGF-β1/SMAD signaling and ROS in mouse heart

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中国药理学与毒理学杂志 2019年第10期 785-786页

作者： meng jia Department of Pharmacology School of Basic Medical Sciences Peking University

OBJECTIVE Adverse cardiac fibrosis is an independent severe risk factor for heart failure and is the leading cause of death in myocardial infarction(MI)patients. The aim of this study was to investigate the potential effect of Ganodermalucidum polysaccharide peptides(GLPPs) on cardiac fibrosis after MI and the underlying mechanisms. METHODS C57 BL/6 mice MI model was set up by ligation of left anterior descending coronary artery. The MI and sham mice were orally gavaged with GLPPs(150 mg·kg·d). After 4 weeks of operation, cardiac function was detected by echocardiography. HE, Masson and Sirius Red staining was performed for histological damage and fibrosis assessment. Expression of FN, α-SMA, COⅢ, TGF-β, SMAD2/3, pSMAD3 were measured in mouse hearts by Western *** rat neonatal cardiac fibroblasts(CFs) were stimulated with TGF-β(10 μg· L) to establish fibrotic fibroblast model and were co-incubated with or without GLPP(6.25, 25 and 100 mg · L) simultaneously for 48 *** of FN, COⅢ, α-SMA, NOX4, SMAD2/3 and pSMAD3 were evaluated by Western blotting. Immunofluorescence staining of Ki67 assessed the cellular proliferation and phalloidin was used to label F-actin of the cytoskeleton to evaluate morphological change of CFs. HO(50 μmol · L, 24 h) was used to stimulate endogenous ROS production in CFs. GLPPs were co-incubated(100 mg·L) simultaneously. Intracellular ROS level was detected with fluorescent probe DCFH-DA. RESULTS Echocardiography performed at 28 d after MI showed signs of cardiac remodeling, particularly a thickening of the interventricular septum and decreased ejection fraction compared with sham group. GLPPs group got a higher fractional shortening and ejection fraction than the MI group. Based on HE staining, the myocardium of GLPPs group exhibited less structural alterations. Masson and Sirius Red staining quantified the fibrosis and GLPPs alleviated cardiac fibrosis. Western blotting confirmed that GLPP reduced the expression of FN, C

关键词： GLPP cardiac fibrosis myofibroblast trans-differentiation NOX4 TGF-β1 ROS

Detecting the Bull’s-Eye Effect in Seismic Inversion Low-Frequency Models Using the Optimized YOLOv7 Model

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Applied Geophysics 2024年第4期21卷 766-776,880,881页

作者： Jun Li jia-bing meng Pan Li Institute of Disaster Prevention Sanhe 065201China Hebei Province University Smart Emergency Application Technology Research and Development Center Sanhe 065201China

To detect bull’s-eye anomalies in low-frequency seismic inversion models,the study proposed an advanced method using an optimized you only look once version 7(YOLOv7)*** model is enhanced by integrating advanced modules,including the bidirectional feature pyramid network(BiFPN),weighted intersection-over-union(wise-IoU),efficient channel attention(ECA),and atrous spatial pyramid pooling(ASPP).BiFPN facilitates robust feature extraction by enabling bidirectional information fl ow across network scales,which enhances the ability of the model to capture complex patterns in seismic inversion ***-IoU improves the precision and fi neness of reservoir feature localization through its weighted approach to ***,ECA optimizes interactions between channels,which promotes eff ective information exchange and enhances the overall response of the model to subtle inversion ***,the ASPP module strategically addresses spatial dependencies at multiple scales,which further enhances the ability of the model to identify complex reservoir *** synergistically integrating these advanced modules,the proposed model not only demonstrates superior performance in detecting bull’s-eye anomalies but also marks a pioneering step in utilizing cutting-edge deep learning technologies to enhance the accuracy and reliability of seismic reservoir prediction in oil and gas *** results meet scientifi c literature standards and provide new perspectives on methodology,which makes signifi cant contributions to ongoing eff orts to refi ne accurate and effi cient prediction models for oil and gas exploration.

关键词： bull’s-eye YOLO bidirectional feature pyramid network weighted intersection-over-union atrous spatial pyramid pooling

Efficient reconstruction scheme for transform domain Wyner-Ziv video coding

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The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 52-57页

作者： WANG Feng-qin FAN Yang-yu jia meng CHEN Yan School of Electronics and Information Northwestern Polytechnical University Xi'an 710072 China School of Computer and Communication Engineering Zhengzhou University of Light Industry Zhengzhou 450002 China

To minimize the errors of the reconstructed values and improve the quality of decoded image, an efficient reconstruction scheme for transform domain Wyner-Ziv （WZ） video coding is proposed. The reconstruction scheme exploits temporal correlation of the coefficient bands, the WZ decoded bits stream and the side information efficiently. When side information is outside the decoded quantization bin, the reconstructed value is derived using expectation of the WZ decoded bit stream and the side information. When side information is within the decoded quantization bin, the reconstructed value is derived using the biased predictor. Simulation results show that the proposed reconstruction scheme gains up to 1.32 dB compared with the commonly used boundary reconstruction scheme at the same bit rates and similar computation cost.

关键词： distributed video coding WZ video coding, transform domain reconstruction

Novel transition and Bellerophon state in coupled Stuart-Landau oscillators

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Frontiers of physics 2019年第3期14卷 107-113页

作者： jia-meng Zhang Xue Li Yong Zou Shu-Guang Guan Department of Physics East China Normal University Shanghai 200241 China

We study synchronization in a system of Stu art-Landau oscillators with frequency-weighted coupling. For three typical unimodal frequency distributions, namely, the Lorentzian, the triangle, and the uniform, we found that the first-order transition occurs when the frequency distribution is relatively compact, while the synchronization transition is continuous when it is relatively wide. In both cases, t here is a regime of Bellerophon state between the incoherent state and the synchronized st ate. Remarkably, we revealed novel transition behavior for such coupled oscillators w计h amplitudes, i.e., the regime of Bellerophon st ate actually contains two stages. In the first stage, the oscillators achieve chaotic phase synchronization;while in the second st age, oscillators form periodical phase synchronization. Our results suggest that Bellerophon state also exists in coupled oscillators with amplitude dynamics.

关键词： synchronization coupled oscillators Stuart-Landau oscillators