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Search Results: 1 - 10 of 119756 matches for " Jiancheng Wang "
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A Comparative Study of “as” and “Which” in Non-Restrictive Relative Clauses  [PDF]
Jiancheng Wang, Junhong Tang
Open Journal of Modern Linguistics (OJML) , 2013, DOI: 10.4236/ojml.2013.34046
Abstract: Both “as” and “which” can introduce a non-restrictive relative clause. But each of them has its own particular function in meaning, part of speech and sentence structure. Therefore sometimes they can have similar usage in a certain situation, while most often they are quite different and can not be used alternatively.
Study on Balance and Improvement of College English Class in China  [PDF]
Junhong Tang, Jiancheng Wang
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.29043
Abstract: Considering the current problems in English class, \"5C\" strategies, cooperation, competition, consideration, creativeness and continuity are used to balance and improve the English class in China on the basis of some fundamentals like “Symbiotic Effect”, “Niche”, “Zone of the Optimum” and “Flowerpots Effect”. Meanwhile, it is also very important and urgent to offer opportunities of further study for English teachers in order to balance and improve the English class according to “Edge Effect”.
Love in Spenser’s Amoretti  [PDF]
Jiancheng Wang, Zhengshuan Li
Advances in Literary Study (ALS) , 2014, DOI: 10.4236/als.2014.21006
Abstract:

Being a sonnet cycle of love with a detailed description of the lady’s physical beauty and the lover’s happy feelings, Amorettiis a story of love between earthlings which is aimed at marriage. Meanwhile, Spenser sanctifies the love by Platonizing and Christianizing the lady. Thus it is clear that the love in the mind of Spenser is not just an earthly one or a heavenly one separately, but both, and, a combination of both earthly love and sacred love.

Emissive mechanism of radio flat spectrum on X-ray binaries
Jiancheng Wang
Physics , 2001,
Abstract: We present that the radio emission with flat spectrum in X-ray binaries comes from the synchrotron emission of relativistic electrons in the high energy tail of hot electrons in continuous conical jet. The jet is assumed to be produced by the advection-dominated accretion flow (ADAF) and maintains ion and electron temperatures constant in the case of adiabatic steady conical expansion. The flat spectrum is result of self-absorbed synchrotron emission by relativistic thermal electrons. We find that the critical frequency at which the radiation becomes optically thin declines along the jet. The emission observed at higher frequencies originates at smaller distance, closer to the base of the jet. The highest cut-off frequency of the flat spectrum is at the base of the jet, and is determined by the physics of the ADAF and the position of the jet formation. We assert that it is a characteristic of the ADAF in black hole X-ray binaries that a continuous steady outflow is formed and causes the observed flat spectrum in the low/hard state. The observed synchrotron emission consists of the flat spectral component from the jet and the steep spectral component from the ADAF. The flat spectral component extends from infrared to radio wavelengths, while the steep spectral component with the 2/5 spectral slope extends from infrared to shorter wavelengths, it will be dominated by the thermal emission from companion star.
Robust Inference for Time-Varying Coefficient Models with Longitudinal Data  [PDF]
Zhaofeng Wang, Jiancheng Jiang, Qunyi Qiu
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.57070
Abstract:

Time-varying coefficient models are useful in longitudinal data analysis. Various efforts have been invested for the estimation of the coefficient functions, based on the least squares principle. Related work includes smoothing spline and kernel methods among others, but these methods suffer from the shortcoming of non-robustness. In this paper, we introduce a local M-estimation method for estimating the coefficient functions and develop a robustified generalized likelihood ratio (GLR) statistic to test if some of the coefficient functions are constants or of certain parametric forms. The robustified GLR test is robust against outliers and the error distribution. This provides a useful robust inference tool for the models with longitudinal data. The bandwidth selection issue is also addressed to facilitate the implementation in practice. Simulations show that the proposed testing method is more powerful in some situations than its counterpart based on the least squares principle. A real example is also given for illustration.

Mechanism of very high energy radiation in BL Lacertae object 3C 66A
Jianping Yang,Jiancheng Wang
Physics , 2009, DOI: 10.1051/0004-6361/200913035
Abstract: Our goal is to understand the nature of blazars and the mechanisms for the generation of high-energy $\gamma$-rays, through the investigation of the blazar 3C 66A. We model the high energy spectrum of 3C 66A, which has been observed recently with the Fermi-LAT and VERITAS telescope. The spectrum has a hard change from the energy range of 0.2-100 GeV to 200-500 GeV in recent almost contemporaneous observations of two telescopes. The de-absorbed VERITAS spectrum greatly depends on the redshift, which is highly uncertain. If z=0.444 is adopted, we are able to use the SSC model to produce the Fermi-LAT component and the EC model to the VERITAS component. However, if z=0.1, the intrinsic VERITAS spectrum will be softer, there will be a smooth link between the Fermi-LAT and VERITAS spectra which can be explained using a SSC model.
Origin of power-law X-ray emission in the Steep power-law state of X-ray Binaries
Jiancheng Wang,Lihong Yan
Physics , 2009,
Abstract: We present a new scenario of the emissive origin in the Steep Power Law (SPL) state of X-ray Binaries. The power-law component of X-ray emission is the synchrotron radiation of relativistic electrons in highly magnetized compact spots orbiting near the inner stable circular orbit (ISCO) of black hole and has a hard spectrum that extends to above MeV bands determined by electron acceleration rate. These photons are then down-scattered by the surrounding plasma and form an observed steep spectrum. The relevance of this model with high-frequency quasi-periodic oscillations (HFQPOs) and extremely high luminosity of the SPL state is discussed.
On the Evolution of the Cores of Radio Sources and Their Extended Radio Emission
Zunli Yuan,Jiancheng Wang
Physics , 2011, DOI: 10.1088/0004-637X/744/2/84
Abstract: The work in this paper aims at determining the evolution and possible co-evolution of radio-loud active galactic nuclei (AGNs) and their cores via their radio luminosity functions (i.e., total and core RLF respectively). Using a large combined sample of 1063 radio-loud AGNs selected at low radio frequency, we investigate the radio luminosity function (RLF) at 408 MHz of steep-spectrum radio sources. Our results support a luminosity-dependent evolution. Using core flux density data of the complete sample 3CRR, we investigate the core RLF at 5.0 GHz. Based on the combined sample with incomplete core flux data, we also estimate the core RLF using a modified factor of completeness. Both results are consistent and show that the comoving number density of radio cores displays a persistent decline with redshift, implying a negative density evolution. We find that the core RLF is obviously different from the total RLF at 408 MHz band which is mainly contributed by extended lobes, implying that the cores and extended lobes could not be co-evolving at radio emission.
A graphical analysis of the systematic error of classical binned methods in constructing luminosity functions
Zunli Yuan,Jiancheng Wang
Physics , 2013, DOI: 10.1007/s10509-013-1402-9
Abstract: The classical 1/Va and PC methods of constructing binned luminosity functions (LFs) are revisited and compared by graphical analysis. Using both theoretical analysis and illustration with an example, we show why the two methods give different results for the bins which are crossed by the flux limit curves $L=L_{lim}(z)$. Based on a combined sample simulated by a Monte Carlo method, the estimate $\phi$ of two methods are compared with the input model LFs. The two methods give identical and ideal estimate for the high luminosity points of each redshift interval. However, for the low luminosity bins of all the redshift intervals both methods give smaller estimate than the input model. We conclude that once the LF is evolving with redshift, the classical binned methods will unlikely give an ideal estimate over the total luminosity range. Page & Carrera (2000) noticed that for objects close to the flux limit $\phi_{1/V_{a}}$ nearly always to be too small. We believe this is due to the arbitrary choosing of redshift and luminosity intervals. Because $\phi_{1/V_{a}}$ is more sensitive to how the binning are chosen than $\phi_{PC}$. We suggest a new binning method, which can improve the LFs produced by the 1/Va method significantly, and also improve the LFs produced by the PC methods. Our simulations show that after adopting this new binning, both the 1/Va and PC methods have comparable results.
YNOGK: A new public code for calculating null geodesics in the Kerr spacetime
Xiaolin Yang,Jiancheng Wang
Physics , 2013, DOI: 10.1088/0067-0049/207/1/6
Abstract: Following \cite{dexagol2009} we present a new public code for the fast calculation of null geodesics in the Kerr spacetime. Using Weierstrass' and Jacobi's elliptic functions, we express all coordinates and affine parameters as analytical and numerical functions of a parameter $p$, which is an integral value along the geodesic. This is a main difference of our code compares with previous similar ones. The advantage of this treatment is that the information about the turning points do not need to be specified in advance by the user, and many applications such as imaging, the calculation of line profiles or the observer-emitter problem, etc become root finding problems. All elliptic integrations are computed by Carlson's elliptic integral method as \cite{dexagol2009} did, which guarantees the fast computational speed of our code. The formulae to compute the constants of motion given by \cite{cunnbard1973} have been extended, which allow one readily to handle the situations, in which the emitter or the observer has arbitrary distance and motion state with respect to the central compact object. The validation of the code has been extensively tested by its application to toy problems from the literature. The source FORTRAN code is freely available for download on the web.
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