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Search Results: 1 - 10 of 33526 matches for " Wenjie Feng "
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A New Method to Select Training Images in Multi-Point Geostatistics  [PDF]
Lixin Wang, Yanshu Yin, Wenjie Feng
Open Journal of Yangtze Oil and Gas (OJOGas) , 2018, DOI: 10.4236/ojogas.2018.32010
Abstract: Training images, as an important modeling parameter in the multi-point geostatistics, directly determine the effect of modeling. It’s necessary to evaluate and select the candidate training image before using the multi-point geostatistical modeling. The overall repetition probability is not sufficient to describe the relationship of single data events in the training image. Based on the understanding, a new method was presented in this paper to select the training image. As is shown in the basic idea, the repetition probability distribution of a single data event was used to characterize the type and stationarity of the sedimentary pattern in the training image. The repetition probability mean value and deviation of single data event reflected the stationarity of the geological model of the training image; the rate of data event mismatching reflected the diversity of geological patterns in training images. The selection of optimal training image was achieved by combining the probability of repeated events and the probability of overall repetition of single data events. It’s illustrated in the simulation tests that a good training image has the advantages of high repetition probability compatibility, stable distribution of repeated probability of single data event, low probability mean value, low probability deviation and low rate of mismatching. The method can quickly select the training image and provide the basic guarantee for multi-point geostatistical simulations.
Analysis of Influence Factors of Tide-Dominated Estuaries Based on Deposition Numerical Simulation  [PDF]
Tao Tang, Jixin Huang, Yanshu Yin, Wenjie Feng
Open Journal of Yangtze Oil and Gas (OJOGas) , 2018, DOI: 10.4236/ojogas.2018.32012
Abstract: Tide-dominated estuaries sedimentary reservoir is a hot area of sedimentology research in recent years, and the important target of oil and gas exploration is one of the relatively few sedimentary systems. Based on the study of underground reservoirs, outcrop and modern sedimentation, scholars believe that the estuary is a sedimentary system formed by transgressive system tract, which is composed of a complex subfacies environment with obvious changes. Its formation is influenced by many factors. The purpose of this paper is to simulate the deposition process of estuaries by Delft-3D software, and to reveal the main controlling factors of estuarine reservoir formation. The factors are as follows. 1) The size of the river flow has a destructive effect on the formation of the estuarine sand bar in the estuary, but the effect is small. 2) Tidal energy plays a constructive role in estuarine sand bars in estuaries, and it is also the main force for the formation of estuarine reservoirs. 3) The composition of the sediments has an obvious influence on the formation of the estuarine reservoir, and the content of the mud is an important factor for the retention of the estuarine sand bar.
The methodology of quantitative assess economic output of climate change
JieMing Chou,WenJie Dong,GuoLin Feng
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4429-8
Abstract: A method is introduced in this paper to study the effect of future climatic change on the economy. The researchers determine the economic output of climate change from historical data, and provide a method to quantitatively predict economic output of climate change by an economic-climatic model. A historical reciprocating examination is used to analyze output data for various crops in eight agricultural areas in China and meteorological data from 160 observatories in China from 1980 to 2000. The results show that the methods used are reasonable to a certain extent and good in application.
Torsional impact response of multiple cylindrical interface cracks between a functionally graded interlayer and homogeneous material

Feng Wenjie~,

力学学报 , 2005,
Abstract: In this paper the problem of multiple cylindrical interface cracks located between a functionallygraded material(FGM)interlayer and its external homogeneous cylinder subjected to torsional impact loading isinvestigated.The FGM interlayer is assumed simultaneously to bond two coaxial dissimilar homogeneous elasticcylinders,and the shear modulus and mass density of the FGM interlayer are assumed to vary continuouslybetween those of the two coaxial materials.The number of cylindrical interface cracks is arbitrary.Themixed boundary value problem is at first reduced to a singular integral equation with a Cauchy type kernel inthe Laplace domain by applying Laplace and Fourier integral transforms and introducing dislocation densityfunction.The singular integral equation is then solved numerically.The dynamic stress intensity factor(DSIF)is also obtained by a numerical Laplace inversion technique.The DSIF is found to rise rapidly to a peak,then oscillate and tend to the static value.The influences of geometric configuration of the cracks and relativemagnitudes of the adjoining material properties are examined.It is found among others that the DSIF can begreatly reduced by increasing the FGM gradient.
Application of an Economy--Climate Model to Assess the Impact of Climate Change

CHOU Jieming,DONG Wenjie,FENG Guolin,

大气科学进展 , 2010,
Abstract: An interdisciplinary investigation was conducted to assess the impact of climate change on grain yields using an economy--climate model (C-D-C). The model was formulated by incorporating climate factors into the classic Cobb-Douglas (C-D) economic production function model. The economic meanings of the model output elasticities are described and elucidated. The C-D-C model was applied to the assessment of the impact of climate change on grain yields in China during the past 20 years, from 1983 through 2002. In the study, the land of China was divided into eight regions, and both the C-D-C and C-D models were applied to each individual region. The results suggest that the C-D-C model is superior to the classic C-D model, indicating the importance of climate factors. Prospective applications of the C-D-C model are discussed.
A Proton Nuclear Magnetic Resonance (1H NMR) Investigation of NaCl-Induced Phase Separation of Acetonitrile-Water Mixtures  [PDF]
Ruizhi Wen, Muqian Yu, Le Jiang, Lili Feng, Wenjie Deng, Bo Chen
American Journal of Analytical Chemistry (AJAC) , 2017, DOI: 10.4236/ajac.2017.810048
Abstract: The microscopic properties of NaCl-induced phase separation of acetonitrile (ACN)-water mixtures have been studied by proton nuclear magnetic resonance (1H NMR). Acetonitrile-rich phase increases with increasing NaCl concentration (cNaCl) at xACN ≈ 0.25. 1H chemical shift of water for acetonitrile-rich phase rapidly decreases with decreasing NaCl mole concentration and that for water-rich phase quickly increases with increasing cNaCl. However, 1H chemical shift of acetonitrile has nothing to do with the molar concentration of NaCl, and it keeps relatively stable for all solutions (±0.002). These results reveal that Na+ and Cl- are rapidly hydrated by water, not by acetonitrile. The change of 1H chemical shift of water has shown that the number of hydrogen bond increases or hydrogen bond strengths with increasing NaCl molarity in mixtures. But hydrogen bond is broken or weaken with the temperature rising. 1H chemical shifts of pure water and the water in acetonitrile-rich phase have been investigated at 293 K, 298 K and 303 K. The hydration number of Na+ (6.05) in water-rich phase is determined by an empirical equation involving 1H chemical shift, temperature and NaCl molarity, which is in good agreement with the literatures.
A New Economic Assessment Index for the Impact of Climate Change on Grain Yield
DONG Wenjie,CHOU Jieming,FENG Guolin,
DONG Wenjie
,CHOU Jieming,FENG Guolin

大气科学进展 , 2007,
Abstract: The impact of climate change on agriculture has received wide attention by the scientific community.This paper studies how to assess the grain yield impact of climate change, according to the climate change over a long time period in the future as predicted by a climate system model. The application of the concept of a traditional "yield impact of meteorological factor (YIMF)" or "yield impact of weather factor" to the grain yield assessment of a decadal or even a longer timescale would be suffocated at the outset because the YIMF is for studying the phenomenon on an interannual timescale, and it is difficult to distinguish between the trend caused by climate change and the one resulting from changes in non-climatic factors. Therefore,the concept of the yield impact of climatic change (YICC), which is defined as the difference in the per unit area yields (PUAY) of a grain crop under a changing and an envisaged invariant climate conditions, is presented in this paper to assess the impact of global climate change on grain yields. The climatic factor has been introduced into the renowned economic Cobb-Douglas model, yielding a quantitative assessment method of YICC using real data. The method has been tested using the historical data of Northeast China,and the results show that it has an encouraging application outlook.

Feng Wenjie Zou Zhenzhu,

力学学报 , 2001,
Abstract: This paper focuses specifically on means of solving the underdetermined problem of limited scattering data inversion. Firstly, by introducing perturbation function of medium parameter, a set of integral equation formulation of elastic wave scattering of 2-D flaw is derived, in which two integral equations are solved for the unknown perturbation function and wave field, given the incident field and scattering data as input. In view of the nonlinear relation between the perturbation function and wave field, variational techniques are applied to find a solution to these equations, and a scheme for regularizing the underdetermined inversion of elastic wave scattering data is further presented which fills in unavailable data such that the boundary of the reconstructed flaw is minimized. This inversion technique is called as a penalty function method. Finally, a lot of identification results are presented for the case of far field measurements taken over limited angular apertures and limited frequency bandwidths. The numerical simulations show that the method presented here is effective in estimating the geometry of discontinuous boundary scattering objects. The demonstrated effectiveness of the regularization suggests possible utility in applications such as nondestructive evaluation for cracks and voids, and the identification of submerged structures.
Microstrip Wideband Bandpass Filter with Six Transmission Zeros Using Transversal Signal-Interaction Concepts
Shujian Xue;Wenjie Feng;Haotian Zhu;Wenquan Che
PIER C , 2013, DOI: 10.2528/PIERC12092814
Abstract: A high-selectivity microstrip wideband bandpass filter with six transmission zeros using transversal signal-interaction concepts is proposed. A fifth-order wide passband with six transmission zeros (0-2, is center frequency of the passband) can be realized two transmission paths. The bandwidth and locations of the transmission zeros can be adjusted conveniently by changing the characteristic impedances of open stub and coupling coefficients of the open/shorted coupled lines. A prototype of planar wideband bandpass filter with 3 -dB fractional bandwidth 43.3% (2.33-3.63 GHz) is designed and fabricated. The measured and simulated results both indicate good performances of high selectivity and wideband harmonic suppression.
Metal-Free Flat Lens Using Negative Refraction by Nonlinear Four-wave Mixing
Jianjun Cao,Yuanlin Zheng,Yaming Feng,Xianfeng Chen,Wenjie Wan
Physics , 2014, DOI: 10.1117/12.2060998
Abstract: A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical meta-materials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered meta-materials usually company by high losses from metals and are extremely difficult to fabricate. An alternative proposal using negative refraction by four-wave mixing has attracted much interests recently, though most of existing experiments still require metals and none of them has been implemented for an optical lens. Here we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a thin glass slide. We realize optical lensing effect utilizing a nonlinear refraction law, which may have potential applications in microscopy.
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