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Search Results: 1 - 10 of 104273 matches for " Longxi Zhang "
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Analysis of Characteristics of the Forecast Jump in the NCEP Ensemble Forecast Products  [PDF]
Xiakun Zhang, Liping Zhang, Jiao Fu, Longxi Zhang
Atmospheric and Climate Sciences (ACS) , 2017, DOI: 10.4236/acs.2017.71011
Abstract: The limit of numerical prediction and ensemble prediction can be further understood by the study of the forecast jump. By using the ensemble average forecast and control forecast product output data for the United States National Environmental Prediction Center (NCEP) global ensemble forecast system (GEFS), and the concept of Jumpiness index from Zsoter et al., we analyzed the statistical characteristics of forecast jump. Results show that, on average, in the NCEP ensemble forecast product, the time average prediction jump index increases with the increase of the forecast aging, and the actual forecast experience can reflect this phenomenon. The consistency of ensemble average forecast is better than the corresponding control forecast. Also, in summer, the frequency of “forecast jump” phenomenon is fluctuating by 17.5%.
Numerical Simulation of the Effects on Low Temperature Drainage from LNG on the Ocean Water Environment  [PDF]
Mingyuan Sun, Yi Zhang, Longxi Han, Bo Chen, Tiantian Liu
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.53B009
In order to research the distribution of thermal field of low temperature discharge from LNG in the ocean, further to formulate reasonable wastewater marine disposal scheme and provide scientific support to the protection of ocean environment, a two-dimensional hydrodynamic model was used to simulate the tide current field in the radial sand ridge group of shallow sea area of Jiangsu maritime space. This model was based on the tide current characteristics near the LNG project and the seasonal design of the typical hydrological conditions in different seasons. This model was used as the hydrodynamic condition that simulated the transport and diffusion for the heat quantity in the change of time and spatial distribution. Considering the comprehensive heat radiation coefficient of water surface, the 2-D water temperature model was established to predict the spatial distribution and temporal variation of the temperature field in the receiving waters. Finally, results showed that the low temperature drainage less affected in the ocean water environment.
Simulation on the Time Progress of the Non-Point Source Pollution Load in Initial Stage Runoff for Small Watershed  [PDF]
Mingyuan Sun, Tiantian Liu, Bo Chen, Yi Zhang, Longxi Han
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.53B008
Taking a reservoir in South China as an example, we use rainfall-runoff unit hydrograph method to analyze the time changing process of surface runoff inflow, which generated by typical design rainfall. On the basis of time series data of flow and water quality in control section of the main rivers in Xili Reservoir, we establish mathematical response relation between non-point source pollutants flux, such as flux of COD, flux of NH3-H, in catchment area of control section and runoff. Then we simulate the time dynamic change progress of non-point source pollution load which generate with the initial stage runoff that generated by design rainfall and flow into reservoir. It can provide technical parameters for the design of non-point source which generate from early runoff treatment project.
Plasma Surface Treatment of BOPP Film by Dielectric Barrier Glow Discharge in Argon/Air  [PDF]
Longxi Chen, Xiangjia Meng, Zhen Mei
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.614205
Abstract: A plasma surface treatment of biaxially oriented polypropylene (BOPP) film was carried out with dielectric barrier glow discharge (DBGD) in Ar/air. The paper studied the effects of the ratios of Ar/air plasma on the BOPP surface modification. The results indicated that the efficiency of the plasma surface modification was improved with increasing treatment time and power density with DBGD in Ar/air. The water contact angle increased first and then decreased with the increase of the Ar/air mixture rate. The DBGD gives a better surface modification than filament discharge. The ageing behavior was influenced by the mixture rate of Ar/air, but the water contact angle of the treated sample was always less than that of un-treated sample.
Expression of p53 in the Effects of Artesunate on Induction of Apoptosis and Inhibition of Proliferation in Rat Primary Hepatic Stellate Cells
Peng Longxi, Fang Buwu, Wang Yuan, Gao Sinan
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026500
Abstract: Background Activation of hepatic stellate cells (HSCs) plays an important role in the development of cirrhosis through the increased production of collagen. p53, the “guardian of the genome”, is a transcription factor that can bind to promoter regions of hundreds of genes where it either activates or suppresses gene expression. Thereby, p53 serves as a tumor suppressor by inducing cell cycle arrest, apoptosis, senescence and DNA repair. Artesunate is a derivative of Artemisinin, Scholars had found it had more extensive pharmacological effects past 10 years. However, little is known about the expression of p53 in the effects of Artesunate on induction of apoptosis and inhibition of proliferation in rat HSCs. Methodology/Principal Findings Isolated and cultured rat primary HSCs in the flask for 10 days to make cells activated. HSCs were divided into two groups: experimental groups and control groups, experimental groups included with various concentrations of Artesunate (125, 150, 175, 200, 225 μmol/L) for 24, 48 and 72 hours. Analysis of MTT revealed that activated HSCs treated with various concentrations of Artesunate (150–225 μmol/L) were inhibited on dose and time-effect relationships; Concentration of hydroxyproline in supernatant was detected by digestive method; Analysis of flow cytometry demonstrated that Artesunate could arrest cell cycle in G1 and induce apoptosis; The nuclear morphological changes in apoptotic cells were evaluated with DNA staining by Hoechst 33258 dye; The expression of p53 were up-regulated showed by western blotting and RT-PCR. Conclusion Artesunate could inhibit HSCs proliferation in dose-dependent and time-dependent manners in vitro through increase the expression of p53.

Qi Longxi,

力学学报 , 1997,
Abstract: The paper deals with the model of runoff and erosion in slope land. The solution to the one dimensional hyperbolic runoff equations and sediment equation are obtained respectively by using the characteristics method and finite difference method. The simulation calculations were conducted for real rain processes and compared with experimental data of field test. The results show that the model and the program are reasonable and practical, and they are useful in the study of the soil erosion.

Qi Longxi,Chao Yong,Wang Boyi,

力学学报 , 2000,
Abstract: The structure and mixing properties of underexpanded turbulent air jets in still water were experimentally investigated in this paper. The experimental system, which consists of compressor, gas tank, injector, water tank as well as pipe, regulator and mount, was built to simulate horizontal sonic jets submerged in water and to measure flow properties of the jets. In order to determine static pressure distribution in the nearfield of the underexpanded jet, two types of horizontally movable, static probes were developed and tested. Static pressures along the axis of jets were obtained for the ratios of static pressures at nozzle passage exit to ambient water being 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0, were illustrated. Using gamma-ray absorption method, where the Gamma-Ray probe is vertically movable, mean void fraction distributions, for the ratios being 1.0 and l.4, were measured at 3 different profiles. Among them, as a reference, the ratio of 1.0 represents the full expansion case. The flow structure and mixing properties were analyzed through the distributions of static pressure and mean void fraction. The results are useful for the analysis of the flow in the external-expansion region near the passage exit. Static pressure measurements show that a shock-wave-containing external-expansion region exists for Underexpanded sonic air jets in water, which is similar to that of underexpanded air jets in air. Underexpanded air jets in water damp faster than underexpanded air jets in air due to different mixing condition. Mixing entrainment layer surrounding the external-expansion region for air jets in water involved a bubble region near the liquid side and a drop-containing region near the gas side.

Qiu Kejian Qi Longxi,Qin Ning,

力学学报 , 1993,
Abstract: In the present paper, numerical simulation of solute transfer in saturated and unsaturated soil is given. The convection and dispersion terms in the equations governing water and salt motion are solved respectively by using Langrangean moving coordinate and Eulerian fixed coordinate systems. Furthermore, cubic spline interpolation method is employed for the projection from the fixed coordinate to the moving coordinate, which makes the model more exact and simpler. The comparisons with theoretical solution in a specific case and experimental results of a soil column in laboratory verify the correctness and reliability of the model. Finally, this model is used for analysis of fresh water leaching. The numerical computation indicates that using shallow mass wells for pumping and draining, the effect of fresh water leaching for saline land reclamation can be greatly enhanced.
Numerical Modelling Of Dusty Atmospheric Flows Over An Erodible Surface

Wang Boyi Chen Qiang Qi Longxi,

力学学报 , 2004,
Abstract: In the framework of the two-fluid model of dilute dusty gases, the present paper gives the governing equations for dusty atmospheric flows, where the two-way coupling is taken into account in the source terms. The similarity criteria are derived for dynamical behaviors of the carrier- and dispersed-phase and they include seven parameters such as the Froude number, the dust mass loading and so on. As a model problem, the aerodynamic entrainment of the dust and sand particles in the fully developed turbulent atmospheric boundary layer over an erodible surface are studied and the aerodynamic drag as well as the Saffman lifting and gravity forces are considered. To overcome the difficulties associated with the non-uniqueness of the flow parameters due to the intersection of particle trajectories, the continuity equation of the dispersed phase is introduced in the Lagrangian coordinates. The motion characteristics and concentration distributions of the dispersed phase are simulated numerically at two different wind speeds and four different particle sizes and the effects of wind velocity and dust size are discussed in detail. These results are also relevant to the energy exchange process between the two phases in the atmospheric boundary layer. The equations, criteria and method may be useful in interpretation of some natural disaster phenomena such as wind erosion and sand-dust storm.

LIU Ming,WANG Boyi,QI Longxi,SHI Honghui,

力学与实践 , 2007,
Abstract: This paper describes the experimental study on gas impinging jets in a cylindrical cavity filled with water.Measurements of the maximum instantaneous pressure in the initiative phase as well as the averaging and fluctuating pressures in the steady phase indicate that,at the stagnation point of the impinging region, these three pressures increase with increasing the nozzle inlet pressure ratio.The obtained results show that the impinging region,bearing the most intensive dynamic load,is the main noise source.Through a comparative approach,it is found that there is a pressure overshoot phenomenon in the water-filling case and its maximum instantaneous pressure is much higher than that in the corresponding gas-filling case.
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