检索结果-南通市图书馆

ASSOCIATION BEHAVIOR OF PORPHYRIN PENDANTS IN pH-SENSITIVE WATER-SOLUBLE POLYMER

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2012年第1期30卷 63-71页

作者： Ke—wei Ding fei Wang fei-peng wu Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

A novel tripyridylporphyrin monomer,5-[4-[2-（acryloyloxy）ethoxy]phenyl]-10,15,20-tris（4-pyridyl）porphyrin （TrPyP）,was synthesized and polymerized with acrylamide（AM） to prepare the hydrophobically associating water-soluble polymer *** aggregation behavior of porphyrin pendants was investigated by UV-Visible and fluorescence *** polymer displays a strong tendency of hydrophobic association even in dilute *** increasing the concentration,the maximum absorption wavelength of Soret band changes from 416 nm to 407 nm,and the fluorescence corrected for the inner filter effect exhibits moderate concentration *** the results indicate thatπ-πinteraction of porphyrin pendants plays a key role in association of PAM-TrPyP,and H-aggregates of porphyrins are mainly formed in the concentrated *** the other hand,dynamic light scattering（DLS） and transmission electron microscopy（TEM） were used to follow the changes in size and structure of the macromolecular assemblies with the concentration *** polymer aggregation conformation changes from loose ＂vesicle-like＂ morphology to solid globule *** pH value of solution decreases to 4.3,pyridine moieties on porphyrin pendants could be protonated and the H-aggregates formed in macromolecular matrix are destroyed by electrostatic repulsion interactions.

关键词： Porphyrin Water-soluble polymer π-πInteractions H-aggregate pH-sensitivity

Study of pollutant transport in depth-averaged flows using random walk method

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2019年第2期31卷 303-316页

作者： Xue-fei wu Dongfang Liang School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China Department of Engineering University of CambridgeCambridgeUK

The random walk particle tracking(RWPT)method is compared with the Eulerian methods in investigating pollutant transport in depth-averaged *** a typical representative of the Eulerian model with high performance,the MacCormack scheme with Total Variation Diminishing modification(TVD-Mac)is selected for *** concentration is simulated in four case ***,both numerical models have been tested in two idealized cases and compared against analytical *** dissipation is observed for TVD-Mac model where the concentration changes abruptly,especially under the circumstances of low resolution and misalignment between the flow direction and grid *** the contrary,simulations by the random walk model achieve higher accuracy in both cases and are free of fictitious oscillations in the vicinity of sharp concentration ***,the solute oscillation along a one-dimensional hypothetical tidal estuary is simulated,with the RWPT accurately con serving mass and suffering less rm merical diffusion compared with the Eulerian ***,the process of pollutant transport in a Yangzte River reach is predicted by the *** longitudinal dispersion coefficient DL is calculated *** is compared favorably with the theoretical/empirical formulae,indicating the validity of the RWPT in solving complex natural problems.

关键词： Pollutant transport depth-averaged flows random walk particle tracking TVD-MacCormack

FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2012年第3期24卷 378-382页

作者： MA fei wu Jian-hua College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control. Based on the theoretical considerations, the experiments of the aerator for a discharge tunnel were conducted, and the relationships between the flow regime and hydraulic and geometric parameters were investigated. The results showed that, there are two kinds of threshold values for the flow regime conversions. One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity, and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity. Two empirical expressions were obtained for the conversions of the flow regimes, which can be used in the designs of the aerators.

关键词： aerator discharge tunnel flow regime filling water jet length

Theoretical Calculations of Optical Spectra and Their Pressure-Induced Shifts of MgAl_2O_4:Cr^(3+)

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第5期49卷 1339-1344页

作者： wu fei ZHANG Ji-Ping College of Physical Science and Technology Sichuan University Chengdu 610065 China

The energy levels of spectrum, wavefunetions and crystal-field parameters of MgAl2O4：Cr^3＋ at normal pressure have been calculated by the means of diagonalizing the complete d^3 energy matrix （DCEM）. With these results, the g factor of the ground state at normal pressure and the pressure-induced shift （PS） of the spectra1 levels are also calculated uniformly, and the calculated results are all in good agreement with the experimental ones. And the contributions of various crystal-field parameters to the energy levels at normal pressure and the variational rates of the R1 line shifting with the pressure are calculated, from which the physical origin of the red shift of the R1 line shifting with increasing pressure have been clearly shown.

关键词： crystal fields energy spectrum g factor high-pressure effect

Fabrication, Sintering and Electrical Properties of (Ca_(0.61),Nd_(0.26))TiO_3 Nanoparticles Doped with Li-Cu-B

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2011年第5期27卷 426-430页

作者： fei wu Qilong Zhang Hui Yang Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China

A sol-gel processing was used to low temperature. Orthorhombic synthesize （Cao.61,Ndo.26）TiO3 （CNT） perovskite structure phase with a smal nanoparticles doped with Li-Cu-B at amount of Li3BO3 secondary phase was formed by calcining the xerogels at 300℃, and monodisperse CNT nano-powders with the grain size of 10-15 nm could be obtained. By using these nanocrystalline CNT powders, dense CNT ceramics could be achieved at the low sintering temperature of 1100℃ due to the effect of the small size nanoparticles and liquid phase Li3BO3. And the dielectric properties with dielectric constant （εr= 89.52）, quality value factors with frequency （Q×f=17148 GHz） and the temperature coefficient of resonant frequency （τf） value of ＋239×10^-6/℃ were achieved.

关键词： Sol-gel preparation Nanomaterials Electrical properties Sintering

A new polar motion prediction method combined with the difference between polar motion series

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2022年第6期13卷 564-572页

作者： Leyang Wang Wei Miao fei wu Faculty of Geomatics East China University of TechnologyNanchang 330013China Key Laboratory of Mine Environmental Monitoring and Improving Around Poyang Lake Ministry of Natural ResourcesNanchang 330013China

After the first Earth Orientation Parameters Prediction Comparison Campaign(1 st EOP PCC),the traditional method using least-squares extrapolation and autoregressive(LS+AR)models was considered as one of the polar motion prediction methods with higher *** traditional method predicts individual polar motion series separately,which has a single input data and limited improvement in prediction *** address this problem,this paper proposes a new method for predicting polar motion by combining the difference between polar motion *** X,Y,and Y-X series were predicted separately using LS+AR ***,the new forecast value of X series is obtained by combining the forecast value of Y series with that of Y-X series;the new forecast value of Y series is obtained by combining the forecast value of X series with that of Y-X *** hindcast experimental comparison results from January 1,2011 to April 4,2021 show that the new method achieves a maximum improvement of 12.95%and 14.96%over the traditional method in the X and Y directions,*** new method has obvious advantages compared with the differential *** study tests the stability and superiority of the new method and provides a new idea for the research of polar motion prediction.

关键词： Earth rotation parameters Polar motion prediction LS+AR Differences between series Mean absolute error

A 3-D numerical simulation of the characteristics of open channel flows with submerged rigid vegetation

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2021年第4期33卷 833-843页

作者： Jun-tao Ren Xue-fei wu Ting Zhang School of Environment and Resource Southwest University of Science and TechnologyMianyang621010China

This paper applies the Flow-3D to investigate the impacts of different flow discharge and vegetation scenarios on the flow velocity (including the longitudinal, transverse and vertical velocities). After the verification by using experimental measurements, a sensitivity analysis is conducted for the vegetation diameter, the vegetation height and the flow discharge. For the longitudinal velocity, the greatest impact on the flow structure originates from the vegetation diameter, rather than the discharge. The vegetation height, however, determines the inflection point of the vertical distribution. Comparing the transverse velocities at two positions in the vegetated area, i.e., the upstream and the downstream, a symmetric pattern is identified along the water depth. The same pattern is also observed for the vertical velocity regardless of the flow or vegetation scenario, including both transverse and vertical fluid circulation patterns in the vegetated area. Moreover, the larger the vegetation diameter is, the more evident these patterns become. The upper circulation occurs near the vegetation canopy. These findings regarding the circulations along the transverse and vertical directions in the vegetated region shed light on the 3-D flow structure through the submerged vegetation.

关键词： Submerged rigid vegetation longitudinal velocity transverse velocity vertical velocity open channel

EXISTENCE OF PERIODIC SOLUTIONS TO AN ISOTHERMAL RELATIVISTIC EULER SYSTEM

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2022年第1期42卷 155-171页

作者： fei wu Zejun WANG Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MHTNanjing 211106China

In this paper,we study the global existence of periodic solutions to an isothermal relativistic Euler system in BV ***,we analyze some properties of the shock and rarefaction wave curves in the Riemann invariant *** on these properties,we construct the approximate solutions of the isothermal relativistic Euler system with periodic initial data by using a Glimm scheme,and prove that there exists an entropy solution V(x,t)which belongs to L^(∞)∩BV_(loc)(R×R_(+)).

关键词： isothermal relativistic Euler system Glimm scheme Riemann problem BV space periodicity

Particle bursts in the inner radiation belt related to global lightning activity

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2013年第11期56卷 2658-2667页

作者： wu fei HAO YongQiang ZHANG DongHe Institute of Space Physics and Applied Technology Peking University State Key Laboratory of Space Weather Chinese Academy of Sciences

Particle bursts （PBs）, the phenomena characterized by short-term increases of particle counting rates （CRs）, were observed by space-borne radiation belt particle detectors. With the electron CR data obtained by National Oceanic and Atmospheric Ad- ministration （NOAA）-18 satellite, the occurrence of PBs in the inner belt （I〈~L〈2 and B〉20.5 gT） were derived for years 2006-2011. The monthly occurrence number of PBs exhibits a strong maximum in northern summer （May-August）. In associ- ation with global lightning data, the seasonal occurrence of PBs is found to be consistent with the lightning activity, especially if only lightning flashes at latitudes 〉20~ are taken into account. The positive correlation between PBs and mid-latitude light- ning discharges indicates the role of lightning-induced whistler waves, and is consistent with the expected pitch-angle scatter- ing by wave-particle interactions. The contribution of lightning is so significant that it forms a non-negligible seasonal back- ground of PBs. If one connects PBs to seismoelectromagnetic emissions （SEME） in attempt to find the earthquake precursor, the lightning background needs to be considered with great care.

关键词： particle burst (PB) wave-particle interaction lightning-induced VLF seismo-electromagnetic emissions (SEME)