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  • Author: Peng Li x
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Peng Wang and Bo Li

Several Differentiation Formulas of Special Functions. Part V

In this article, we give several differentiation formulas of special and composite functions including trigonometric, polynomial and logarithmic functions.

Open access

Bo Li and Peng Wang

Several Differentiation Formulas of Special Functions. Part IV

In this article, we give several differentiation formulas of special and composite functions including trigonometric function, polynomial function and logarithmic function.

Open access

Zhang Peng and Li Hong-Bin

Power System Frequency Estimation Algorithm for Electric Energy Metering of Nonlinear Loads

In this paper, a discrete wavelet transform (DWT) based approach is proposed for power system frequency estimation. Unlike the existing frequency estimators mainly used for power system monitoring and control, the proposed approach is developed for fundamental frequency estimation in the field of energy metering of nonlinear loads. The characteristics of a nonlinear load is that the power signal is heavily distorted, composed of harmonics, inter-harmonics and corrupted by noise. The main idea is to predetermine a series of frequency points, and the mean value of two frequency points nearest to the power system frequency is accepted as the approximate solution. Firstly the input signal is modulated with a series of modulating signals, whose frequencies are those frequency points. Then the modulated signals are decomposed into individual frequency bands using DWT, and differences between the maximum and minimum wavelet coefficients in the lowest frequency band are calculated. Similarities among power system frequency and those frequency points are judged by the differences. Simulation results have proven high immunity to noise, harmonic and inter-harmonic interferences. The proposed method is applicable for real-time power system frequency estimation for electric energy measurement of nonlinear loads.

Open access

Peng Song, Li Zhao and Yongqiang Bao

Abstract

The Gaussian mixture model (GMM) method is popular and efficient for voice conversion (VC), but it is often subject to overfitting. In this paper, the principal component regression (PCR) method is adopted for the spectral mapping between source speech and target speech, and the numbers of principal components are adjusted properly to prevent the overfitting. Then, in order to better model the nonlinear relationships between the source speech and target speech, the kernel principal component regression (KPCR) method is also proposed. Moreover, a KPCR combined with GMM method is further proposed to improve the accuracy of conversion. In addition, the discontinuity and oversmoothing problems of the traditional GMM method are also addressed. On the one hand, in order to solve the discontinuity problem, the adaptive median filter is adopted to smooth the posterior probabilities. On the other hand, the two mixture components with higher posterior probabilities for each frame are chosen for VC to reduce the oversmoothing problem. Finally, the objective and subjective experiments are carried out, and the results demonstrate that the proposed approach shows greatly better performance than the GMM method. In the objective tests, the proposed method shows lower cepstral distances and higher identification rates than the GMM method. While in the subjective tests, the proposed method obtains higher scores of preference and perceptual quality.

Open access

Caiyun Gu, Peng Zhao, Li Wang and Hongxia Guo

Abstract

To solve the problem of offshore oilfield development, based on the newly introduced pulsed neutron oxygen activation logging instrument, the application research of test design and interpretation method was carried out and applied to actual production. The structure, technical indicators and logging principles of pulsed neutron oxygen activation logging tools were introduced. The test design under different well conditions was studied, including general positive and negative injection, oil sleeve injection, single oil pipe configuration and multitubing configuration. A large amount of field test data was collected and analysed technically. A set of effective interpretation models was proposed. The corresponding interpretation software was developed. A set of test design methods and operating specifications for different well conditions were developed. Based on the conventional interpretation method, the peak selection, the double-tuber peak identification and the carbon dioxide flooding interpretation method were added. The results show that the test design and interpretation methods were applied well through a large number of field tests and production applications. Therefore, pulsed neutron oxygen activated injection profile logging technology is successfully applied in offshore oil fields.

Open access

Peng Song, Yun Jin, Li Zhao and Cairong Zou

Abstract

A novel VC (voice conversion) method based on hybrid SVR (support vector regression) and GMM (Gaussian mixture model) is presented in the paper, the mapping abilities of SVR and GMM are exploited to map the spectral features of the source speaker to those of target ones. A new strategy of F0 transformation is also presented, the F0s are modeled with spectral features in a joint GMM and predicted from the converted spectral features using the SVR method. Subjective and objective tests are carried out to evaluate the VC performance; experimental results show that the converted speech using the proposed method can obtain a better quality than that using the state-of-the-art GMM method. Meanwhile, a VC method based on non-parallel data is also proposed, the speaker-specific information is investigated using the SVR method and preliminary subjective experiments demonstrate that the proposed method is feasible when a parallel corpus is not available.

Open access

Guangzhong Li, Yang Yu and Peng Bai

Methanol and acetonitrile form a minimum azeotrope at 336.74 K, which contains methanol 76.89 mas%. The simulation and the experiment to separate the mixture by batch extractive distillation using aniline as entrainer is performed. Based on the experimental and simulative VLE data, aniline is chosen to be the suitable solvent. The sensitivity analysis about the number of stages, the refl ux ratio, the solvent feed stage and the solvent fl ow rate is conducted to obtain the optimal parameters and confi guration of the extractive distillation column with minimal energy requirements. The most appropriate confi guration is 30 theoretical stages. The optimal entrainer feeding stage is 8 with a solvent fl ow rate of 20kg/h and the refl ux ratio of 2.0, respectively. The simulation results show the effect of the main variables on the extractive distillation process. The experiment is carried out to corroborate the feasibility of the separation of methanol-acetonitrile by batch extractive distillation.

Open access

Qintai Yang, Peng Li, Yangqiu Li, Xiuli Wu, Xuekun Huang, Yulian Chen and Gehua Zhang

Effects of Immunotherapy on the Distribution and Clonality of TCR Vγ and Vδ Subfamily T Cells in Allergic Rhinitis Patients

The aim of this study was to investigate the changes in the peripheral specific IgE level, distribution of TCR Vg and Vd subfamily T cells and mRNA expressions of TCR Vg I-III following specific immunotherapy (SIT) with house-dust-mite extract in allergic rhinitis (AR) patients. Ten AR patients undergoing SIT with house-dust-mite extract for 1 year were recruited. Quantitative analysis of immunofluorescence was performed to detect the serum specific IgE (sIgE) level before and after SIT; RT-PCR-genescan analysis was employed to detect the mRNA expressions of TCR Vg (I-III) and Vd (1-8) in the peripheral mononuclear cells followed by analysis of T cell clonality. Real-time quantitative PCR was applied to detect the expressions of TCR Vg I-III genes. Ten healthy volunteers served as controls. For AR patients, SIT treatment could improve the symptoms, but the serum sIgE level was not markedly decreased. Before SIT, the expressions of TCR Vg I-III gene were similar between AR patients and controls (P>0.05) but markedly decreased after SIT in AR patients (P<0.05 in TCR VgI and VgII). The expressions of TCR Vd (1-8) before and after SIT were 5.3±0.82 and 4.9±0.57, respectively, and that in healthy controls was 5.2±1.40. Vd1, 2, 3 and 6 were the most common genes found in these patients. Significant difference in the TCR Vd6 subfamily T cells was found between the two groups. Polyclonal or biclonal proliferation was found in the T cells of patients before SIT and in healthy controls, but oligoclonal proliferation in only 1 subject before SIT. After SIT, the proportion of patients with oligoclonal proliferation of T cells (6/10) was markedly increased (P<0.05). SIT for 1 year could alter the expressions of TCR Vg I-III genes, the distribution of TCR Vg and Vd T cells and the ways in which T cells proliferate. The early improvement of symptoms following immunotherapy might not be related to the serum sIgE content in AR patients, but associated with the TCR gd T cells, especially the TCR V d6 T cells.