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Search Results: 1 - 10 of 42839 matches for " Yan Gong "
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Application of Improved Analysis of Variance to Ionospheric TEC Short-Term Forecast  [PDF]
Yan Gong, Yamin Dang
Positioning (POS) , 2011, DOI: 10.4236/pos.2011.21005
Abstract: An improved superposition analysis of periodical wave variance is used for short-term forecast of the ionosphere TEC in this study. Using the ionospheric TEC data provided by IGS as the real value, the forecasting precision of this me-thod at different locations in China with 40 days data is evaluated. The result shows that the improved method has a better forecasting precision which could reach 1.1 TECU. But the forecasting precision still relates to geographical position, it is proportional to longitude and inversely proportional to latitude. Compared with the current-used methods, the improved method has many advantages as higher precision, using fewer parameters and easier to calculate. So, it applied to ionosphere short-term prediction in China very well.
Oxidative Decarboxylation of Levulinic Acid by Silver(I)/Persulfate
Yan Gong,Lu Lin
Molecules , 2011, DOI: 10.3390/molecules16032714
Abstract: The oxidative decarboxylation of levulinic acid (LA) by silver(I)/persulfate [Ag(I)/S2O82?] has been investigated in this paper. The effects of buffer solution, initial pH value, time and temperature and dosages of Ag(I)/S2O82? on the decarboxylation of LA were examined in batch experiments and a reaction scheme was proposed on basis of the reaction process. The experimental results showed that a solution of NaOH-KH2PO4 was comparatively suitable for the LA decarboxylation reaction by silver(I)/persulfate. Under optimum conditions (temperature 160 °C, pH 5.0, and time 0.5 h), the rate of LA conversion in NaOH-KH2PO4 solutions with an initial concentration of 0.01 mol LA reached 70.2%, 2-butanone (methyl ethyl ketone) was the single product in the gas phase and the resulted molar yield reached 44.2%.
Pronunciation Proficiency Evaluation based on Discriminatively Refined Acoustic Models
Ke Yan,Shu Gong
International Journal of Information Technology and Computer Science , 2011,
Abstract: The popular MLE (Maximum Likelihood Estimation) is a generative approach for acoustic modeling and ignores the information of other phones during training stage. Therefore, the MLE-trained acoustic models are confusable and unable to distinguish confusing phones well. This paper introduces discriminative measures of minimum phone/word error (MPE/MWE) to refine acoustic models to deal with the problem. Experiments on the database of 498 people’s live Putonghua test indicate that: 1) Refined acoustic models are more distinguishable than conventional MLE ones; 2) Even though training and test are mismatch, they still perform significantly better than MLE ones in pronunciation proficiency evaluation. The final performance has approximately 4.5% relative improvement.
Fuzzy Mathematical Method Based Comprehensive Security Evaluation Model of the Railway Operating Tunnel
Gong Li,YAN Songhong
Information Technology Journal , 2013,
Abstract: The railway operating tunnel security evaluation is the chief problem in the tunnel operation and management. There are many factors affect the railway tunnel security. And there are great harms in the safety incidents. So the heart of ensuring operational safety is to establish effective security risk evaluation model in the security monitoring. The fuzzy mathematical method was used in this study to estimate the railway operating tunnel security evaluation index and construct the evaluation index system. On the basis of the main factors that affect the railway operating tunnel security, this study classified the main parameters according to the corresponding indexes. Furthermore, it proposed the railway operating tunnel security evaluation model and method which combined the qualitative and quantitative analysis together. The study considered the security evaluation indexes weight by the expert evolution method. Then it gave the security level standard for the evaluation result. Compared with the existing railway security evaluation method, this fuzzy comprehensive evaluation model can better reflect the actual situation to the railway tunnel. And the model has high reliability and accuracy.
The extragalactic background light from the measurements of the attenuation of high-energy gamma-ray spectrum
Yan Gong,Asantha Cooray
Physics , 2013, DOI: 10.1088/2041-8205/772/1/L12
Abstract: The attenuation of high-energy gamma-ray spectrum due to the electron-positron pair production against the extragalactic background light (EBL) provides an indirect method to measure the EBL of the universe. We use the measurements of the absorption features of the gamma-rays from blazars as seen by Fermi Gamma-ray Space Telescope to explore the EBL flux density and constrain the EBL spectrum, star formation rate density (SFRD) and photon escape fraction from galaxies out to z=6. Our results are basically consistent with the existing determinations of the quantities. We find a larger photon escape fraction at high redshifts, especially at z=3, compared to the result from the recent Ly-alpha measurements. Our SFRD result is consistent with the data from both gamma-ray burst and UV observations in 1-sigma level. However, the average SFRD we obtain at z>~3 matches the gamma-ray data better than the UV data. Thus our SFRD result at z>~6 favors that it is sufficiently high enough to reionize the universe.
Evidence of residual Doppler shift on three pulsars, PSR B1259-63, 4U1627-67 and PSR J2051-0827
Biping Gong,Zhiqiang Yan
Physics , 2014,
Abstract: The huge derivative of orbital period observed in binary pulsar PSR B1259-63, the torque reversal displaying on low mass X-ray binary, 4U1627-67 and the long term change of orbital period of PSR J2051-0827, seem totally unrelated phenomena occurring at totally different pulsar systems. In this paper, they are simply interpreted by the same mechanism, residual Doppler shift. In a binary system with periodic signals sending to an observer, the drift of the signal frequency actually changes with the varying orbital velocity, projected to line of sight at different phases of orbit. And it has been taken for granted that the net red-shift and blue-shift of an full orbit circle be cancelled out, so that the effect of Doppler shift to the signal in binary motion cannot be accumulated over the orbital period. However, taking the propagation time at each velocity state into account, the symmetry of the velocity distribution over the orbital phase is broken. Consequently, the net Doppler shift left in an orbit is non-zero. Understanding this Newtonian second Doppler effect not only makes pulsars better laboratory in the test of gravitational effects, but also allows us to extract the angular momentum of the pulsar of PSR J2051-0827, $\leq 2\times 10^{43}gcm^2$; and the accretion disc of 4U 1627-67, $7\times 10^{50} gcm^2/s$, respectively, which are of importance in the study of structure of neutron stars and the physics of accretion disc of X-ray binaries.
Adaptive finite element method for elliptic optimal control problems: convergence and optimality
Wei Gong,Ningning Yan
Mathematics , 2015,
Abstract: In this paper we consider the convergence analysis of adaptive finite element method for elliptic optimal control problems with pointwise control constraints. We use variational discretization concept to discretize the control variable and piecewise linear and continuous finite elements to approximate the state variable. Based on the well-established convergence theory of AFEM for elliptic boundary value problems, we rigorously prove the convergence and quasi-optimality of AFEM for optimal control problems with respect to the state and adjoint state variables, by using the so-called perturbation argument. Numerical experiments confirm our theoretical analysis.
Weighted $L^p$ estimates for the area integral associated to self-adjoint operators
Ruming Gong,Lixin Yan
Mathematics , 2011,
Abstract: This article is concerned with some weighted norm inequalities for the so-called horizontal (i.e. involving time derivatives) area integrals associated to a non-negative self-adjoint operator satisfying a pointwise Gaussian estimate for its heat kernel, as well as the corresponding vertical (i.e. involving space derivatives) area integrals associated to a non-negative self-adjoint operator satisfying in addition a pointwise upper bounds for the gradient of the heat kernel. As applications, we obtain sharp estimates for the operator norm of the area integrals on $L^p(\RN)$ as $p$ becomes large, and the growth of the $A_p$ constant on estimates of the area integrals on the weighted $L^p$ spaces.
Some Notes on Constructions of Binary Sequences with Optimal Autocorrelation
Tongjiang Yan,Guang Gong
Computer Science , 2014,
Abstract: Constructions of binary sequences with low autocorrelation are considered in the paper. Based on recent progresses about this topic, several more general constructions of binary sequences with optimal autocorrelations and other low autocorrelations are presented.
Analysis on the Spinning Process and Properties of Tencel Yarn  [PDF]
Ya Wang, Dudi Gong, Yan Bai, Yunqi Zhai
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2015, DOI: 10.4236/jmmce.2015.31006
Abstract: Tencel fiber, as a new type of green environmental protection fiber, is drawing attention from the society and people’s favorite. In paper, the spinning process and properties of tencel yarn were studied. Also traditional cotton yarn was tested and compared to understand tencel better as they are now both widely used in apparel. Compared with cotton yarn of the same count, the weight CV of tencel quality is lower, while the twist CV is higher; breaking elongation of tencel yarn is larger, while CV of breaking elongation of tencel yarn is slightly higher; unevenness of tencel spinning yarn is lower.
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