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Absolute Orientation of Molecules with Competing Hydrophilic Head Groups at the Air/Water Interface Probed with Sum Frequency Generation Vibrational Spectroscopy

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Chinese Journal of Chemical Physics 2009年第2期22卷 197-203页

作者： feng Wang zhi Huang zhi-feng Cui Hong-fei Wang Department of Physics Anhui Normal University Wuhu 241000 China Beijing National Laboratory for Molecular Sciences State Key Laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China

The constructive or destructive spectral interference between the molecular groups oriented up and down at the interface in the sum-frequency generation （SFG） spectra provides a direct measurement of the absolute orientation of these molecular groups. This simple approach can be employed to interrogate absolute molecular orientations other than using the complex absolute phase measurement in the SFG studies. We used the -CN group in the p-cyanophenol （PCP） molecule as the internal phase standard, and we measured the phases of the SFG fields of the -CN groups in the 3,5-dimethyl-4-hydroxy-benzonitrile （35DMHBN） and 2,6-dimethyl-4-hydroxy-benzonitrile （26DMHBN） at the air/water interface by measuring the SFG spectra of the aqueous surfaces of the mixtures of the PCP, 35DMHBN, and 26DMHBN solutions. The results showed that the 35DMHBN had its -CN group pointing into the aqueous phase; while the 26DMHBN, similar to the PCP, had its -CN group pointing away from the aqueous phase. The tilt angles of the -CN group for both the 35DMHBN and 26DMHBN molecules at the air/water interface were around 25°-45° from the interface normal. These results provided insights on the understanding of the detailed balance of the competing factors, such as solvation of the polar head groups, hydrogen bonding and hydrophobic effects, etc., on influencing the absolute molecular orientation at the air/water interface.

关键词： Sum frequency generation vibrational spectroscopy Air/water interface Molecule orientation p-cyanophenol

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光谱辐射照度国际关键比对装置、方法与结果分析

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光谱学与光谱分析 2025年第1期45卷 1-7页

作者：代彩红王彦飞李玲吴志峰谢一航中国计量科学研究院光学与激光计量科学研究所北京100029

基于高温黑体辐射源和双光栅光谱辐射比较测量系统,中国计量科学研究院自主研制了新一代光谱辐射照度国家基准装置,波长范围覆盖230~2550 nm,以一组稳定的卤钨灯作为副基准灯组,保存和传递光谱辐射照度量值。黑体的温度溯源至铂-碳Pt-C... 详细信息

基于高温黑体辐射源和双光栅光谱辐射比较测量系统,中国计量科学研究院自主研制了新一代光谱辐射照度国家基准装置,波长范围覆盖230~2550 nm,以一组稳定的卤钨灯作为副基准灯组,保存和传递光谱辐射照度量值。黑体的温度溯源至铂-碳Pt-C和铼-碳Re-C共晶点黑体,在3021 K采用钨碳-碳WC-C共晶点黑体进行验证。采用新基准装置,2017年-2019年NIM参加国际计量局组织的光谱辐射照度国际关键比对CCPR-K1.a,比对由全俄光学物理学测量研究院(VNIIOFI)主导,共有12个实验室参加。比对结果表明:除少数实验室外,在250~290、300~1300、1500~2500 nm波长范围,各参比实验室之间的一致性分别为±2.0%、±1.0%和±2.0%。在紫外、可见和近红外波段,NIM与国际比对参考值的平均相对偏差分别为0.13%、0.28%和0.15%。在250~2500 nm全波段,NIM与国际比对参考值的平均相对偏差为0.17%,与2004年平均相对偏差0.9%相比,测量能力提升显著。

关键词：光谱辐射照度国际比对高温黑体测量不确定度国家基准

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Onboard real time modeling of aircraft engines with Hammerstein-Wiener representation

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航空动力学报 2014年第10期29卷 2499-2506页

作者： WANG Ji-qiang YE zhi-feng HU Zhong-zhi Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics

An identification-based approach for aircraft engine modeling using the nonlinear HammersteinWiener representation was ***-Wiener modeling for both limited flight envelope and extended flight envelope was *** shows that the resulting model can be valid over 10%variation of rotational speed of the engine,compared with those linear models that are only valid over 3%—5%change of rotational *** is further demonstrated that the proposed method can be utilized over large envelope up to 20% variation of rotational speed of the *** fundamental idea is to use nonlinear models to extend the feasible/valid region rather than those linear *** may consequently simplify the switching logic in the onboard digital control *** is often overlooked in aircraft engine control community,but has been emphasized in the research.

关键词： aircraft engines engine modeling onboard real time modeling system identification Hammerstein-Wiener representation

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Passivity-based consensus for linear multi-agent systems under switching topologies

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Control Theory and Technology 2014年第3期12卷 304-316页

作者： zhi feng Guoqiang HU School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798

This paper studies the passivity-based consensus analysis and synthesis problems for a class of stochastic multi-agent systems with switching topologies. Based on Lyapunov methods, stochastic theory, and graph theory, new different storage Lyapunov functions are proposed to derive sufficient conditions on mean-square exponential consensus and stochastic passivity for multi-agent systems under two different switching cases, respectively. By designing passive time-varying consensus protocols, the solvability conditions for the passivity-based consensus protocol synthesis problem, i.e., passification, are derived based on linearization techniques. Numerical simulations are provided to illustrate the effectiveness of the proposed methods.

关键词： Consensus Linear multi-agent systems Passivity and passification Networks with switching topology

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NUMERICAL INVESTIGATION OF CAVITATION PERFORMANCE OF SHIP PROPELLERS

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Journal of Hydrodynamics 2012年第3期24卷 347-353页

作者： ZHU zhi-feng FANG Shi-liang Key Laboratory of Underwater Acoustic Signal Processing Ministry of Education Southeast University Nanjing 210096 China School of Electrical Engineering and Information Anhui University of Technology Maanshan 243002 China Key Laboratory of Underwater Acoustic Signal Processing Ministry of Education Southeast University Nanjing 210096 China

The cavitation performance of propellers is studied based on viscous multiphase flow theories. With a hybrid grid based on Navier-Stokes （N-S） and bubble dynamics equations, some recent validation results are presented in this paper in the predictions of the thrust, the torque and the vapor volume fraction on the back side of propeller blade for a uniform inflow. The numerical predictions of the hydrodynamic performance and the sheet cavitation under several operating conditions for two propellers agree with the corresponding measured data in general. The thrust and the torque are plotted with respect to the advance rate and the cavitation number. The cavitation performance breakdown is closely related to the strong sheet cavitation around propellers. The models with parameters modified are shown to predict the propeller cavitation well.

关键词： cavitation Reynolds-Averaged Navier-Stokes (RANS) propeller sliding mesh multiphase flow

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Numerical Prediction of Tip Vortex Cavitation for Marine Propellers in Non-uniform Wake

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Chinese Journal of Mechanical Engineering 2017年第4期30卷 804-818页

作者： zhi-feng Zhu Fang Zhou Dan Li School of Electrical and Information Engineering AnhuiUniversity of Technology Maanshan 243032 China

Tip vortex cavitation is the first type of cavita- tion to take place around most marine propellers. But the numerical prediction of tip vortex cavitation is one of the challenges for propeller wake because of turbulence dis- sipation during the numerical simulation. Several parame- ters of computational mesh and numerical algorithm are tested by mean of the predicted length of tip vortex cav- tiation to validate a developed method. The predicted length of tip vortex cavtiation is on the increase about 0.4 propeller diameters using the developed numerical method. The predicted length of tip vortex cavtiation by RNG k - e model is about 3 times of that by SST k - ~o model. Therefore, based on the validation of the present approach, the cavitating flows generated by two rotating propellers under a non-uniform inflow are calculated further. The distributions of axial velocity, total pressure and vapor volume fraction in the transversal planes across tip vortex region are shown to be useful in analyzing the feature of the cavitating flow. The strongest kemel of tip vortex cavitation is not at the position most close to blade tip but slightly far away from the region. During the growth of tip vortex cavitation extension, it appears short and thick, and then it becomes long and thin. The pressure fluctuations at the positions inside tip vortex region also validates the conclusion. A key finding of the study is that the grids constructed especially for tip vortex flows by usingseparated computational domain is capable of decreasing the turbulence dissipation and correctly capturing the fea- ture of propeller tip vortex cavitation under uniform and non-uniform inflows. The turbulence model and advanced grids is important to predict tip vortex cavitation.

关键词： Cavitation Propeller Tip vortex Numericalprediction

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Effect of Stokes number on energy modulation of the fluid in turbulent particle-laden channel flows

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Journal of Hydrodynamics 2022年第3期34卷 510-521页

作者： zhi-feng Wu Jian-zhao Wu Bo-fu Wang zhi-ming Lu Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The effect of Stokes number on the kinetic energy(KE)budget in particle-laden turbulent channel flows is examined by conducting two-way coupled direct numerical simulations using the Eulerian-Lagrangian *** friction Reynolds number of the single phase channel flow is Re_(τ)=180,the particle mass loading and volume fraction areφ_(m)=0.2,φ_(v)≈10−4,and the Stokes numbers range from St^(+)=14–*** statistics show that due to the presence of solid particles,the mean velocity is reduced in the vicinity of the wall but enhanced in the outer region,and the off-streamwise intensity of fluctuated velocity and the Reynolds stress are reduced in the whole *** analysis on the budgets of turbulent kinetic energy(TKE)finds that the presence of particles induces a significant reduction on both the production and dissipation *** increasing Stokes number St^(+),both the production and dissipation rates exhibit non-monotonical trends,i.e.,both initially decrease for St^(+)*** suggests that the particle-induced suppression on TKE production and dissipation is the strongest nearly at St^(+)=*** is also found that particles act as an additional sink/source term in the budgets of both mean-flow kinetic energy(MKE)and *** addition,we investigate the influence of St^(+)on the“zero point”which indicates the balance of exchanging energy between the particle and fluid *** is shown that with increasing St^(+),the“zero point”moves toward the wall,suggesting that the position of perfect following between particle and fluid is closer to the wall with larger St^(+).The present results reveal the Stokes number effects on the spatial transport mechanisms of MKE,TKE in turbulent channel flows laden with inertial particles.

关键词： Particle-laden flows two-way coupling Stokes numbers kinetic energy budgets

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Sequential intraventricular injection of tigecycline and polymyxin B in the treatment of intracranial Acinetobacter baumannii infection after trauma: a case report and review of the literature

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Military Medical Research 2020年第4期7卷 497-502页

作者： Li Zhong Xue-zhi Shi Lei Su zhi-feng Liu Second Clinical College of Guangzhou University of Chinese Medicine Guangzhou 510515China Department of Critical Care Medicine the First Affiliated Hospital of Guizhou University of Chinese MedicineGuiyang 550001China Department of Critical Care Medicine General Hospital of Southern Theater Command of PLAGuangzhou 510010China Key Laboratory of Hot Zone Trauma Care and Tissue Repair of PLA General Hospital of Southern Theater Command of PLAGuangzhou 510010China

Background:Intracranial infection after craniotomy is one of the most serious postoperative complications,especially multidrug-resistant(MDR)or extensively drug-resistant(XDR)bacterial meningitis,and strongly affects the prognosis of *** treatment experience regarding these infections is *** presentation:We report a case of severe intracranial infection of XDR Acinetobacter baumannii(***)that was treated by intravenous(IV)injection,sequential intraventricular(IVT)injection of tigecycline and polymyxin B,and other anti-infective *** results were obtained,and the patient was eventually discharged from the *** case is characterized by intracranial ***:The polymyxin B IV+IVT pathway is an ideal treatment strategy for XDR *** tigecycline IVT pathway is also a safe treatment option.

关键词： Intraventricular injection of tigecycline Polymyxin B Intracranial infection Acinetobacter baumannii

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Supercritical fluid extraction and gas chromatography analysis of arsenic species from solid matrices

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Chinese Chemical Letters 2016年第2期27卷 241-246页

作者： zhi-feng Wang Zhao-Jie Cui School of Environmental Science and Engineering Shandong University

A method in combination with derivatization-supercritical fluid extraction（SFE） and gas chromatography（GC） for the speciation and quantitative determination of dimethylarsinate（DMA）, monomethylarsonate（MMA） and inorganic arsenic in solid matrices was investigated. Thioglycolic acid methyl ester（TGM） and thioglycolic acid ethyl ester（TGE） were evaluated as derivatization reagents. The effects of pressure, temperature, flow rate of supercritical CO_2, extraction time, modifier and microemulsion on the efficiency of extraction were systematically investigated. The procedure was applied to the analysis of real soil and sediment samples. Results showed that TGE was more effective for arsenic speciation as a derivatization reagent. Modifying supercritical CO_2 with methanol can greatly improve the extraction efficiency. Further, the addition of microemulsion containing surfactant Triton X-100 can further enhance recoveries of arsenic species. The optimum extraction conditions were 100 ℃, 30 MPa, 10 min static and 25 min dynamic extraction with 5%（v/v） methanol, and surfactant modified supercritical CO_2. Detection limits in solid matrices were 0.15, 0.3 and 1.2 mg/kg for DMA, MMA and inorganic arsenic,respectively. The method was validated by the recovery data. The resulting method was fast, easy to perform and selective in the extraction and detection of various arsenic species in solid matrices.

关键词： Supercritical fluid extraction Arsenic species analysis Thioglycolic acid methyl ester(TGM) Thioglycolic acid ethyl ester(TGE) Derivatization Gas chromatography

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Predicting jet-grout column diameter to mitigate the environmental impact using an artificial intelligence algorithm

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Underground Space 2021年第3期6卷 267-280页

作者： zhi-feng Wang Wen-Chieh Cheng School of Highway Chang’an UniversityXi’an 710064China Department of Statistics Virginia Polytechnic Institute and State UniversityBlacksburg 24060United States School of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering(XAUAT) Xi’an 710055China

This paper describes an approach for predicting the diameter of a jet-grout column using the support vector regression(SVR)technique,which is regarded as a novel learning machine based upon recent advances in statistical theory,in which the combined effects of the construction(construction methods and jetting parameters)and soil properties(soil type and shearing resistance)are *** different kernel functions,namely,a linear kernel function,polynomial kernel function,radial basis kernel function,and sigmoid kernel function,are integrated into the SVR technique.A large amount of field measured data on the diameter of jet-grout column are retrieved from the published literature for training and testing *** results indicate that the SVR technique with a radial basis kernel function provides predictions closest to the measured results,whereas the prepared design charts enable the ability to significantly widen the application of the proposed approach to the areas of ground improvement and environmental protection.

关键词： Jet grouting Support vector regression Machine learning Radial basis function

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