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  • Author: Nan Li x
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Open access

Sheng-nan Gong and Jing-li Fu

Abstract

This paper propose Noether symmetries and the conserved quantities of the relative motion systems on time scales. The Lagrange equations with delta derivatives on time scales are presented for the system. Based upon the invariance of Hamilton action on time scales, under the infinitesimal transformations with respect to the time and generalized coordinates, the Hamilton’s principle, the Noether theorems and conservation quantities are given for the systems on time scales. Lastly, an example is given to show the application the conclusion.

Open access

Yong Liao, Zhen-Nan Fan, Li Han and Li-Dan Xie

Abstract

In order to research the losses and heat of damper bars thoroughly, a multislice moving electromagnetic field-circuit coupling FE model of tubular hydro-generator and a 3D temperature field FE model of the rotor are built respectively. The factors such as rotor motion and non-linearity of the time-varying electromagnetic field, the stator slots skew, the anisotropic heat conduction of the rotor core lamination and different heat dissipation conditions on the windward and lee side of the poles are considered. Furthermore, according to the different operating conditions, different rotor structures and materials, compositive calculations about the losses and temperatures of the damper bars of a 36 MW generator are carried out, and the data are compared with the test. The results show that the computation precision is satisfied and the generator design is reasonable.

Open access

Ting-ao Shen, Hua-nan Li, Qi-xin Zhang and Ming Li

Abstract

The convergence rate and the continuous tracking precision are two main problems of the existing adaptive notch filter (ANF) for frequency tracking. To solve the problems, the frequency is detected by interpolation FFT at first, which aims to overcome the convergence rate of the ANF. Then, referring to the idea of negative feedback, an evaluation factor is designed to monitor the ANF parameters and realize continuously high frequency tracking accuracy. According to the principle, a novel adaptive frequency estimation algorithm based on interpolation FFT and improved ANF is put forward. Its basic idea, specific measures and implementation steps are described in detail. The proposed algorithm obtains a fast estimation of the signal frequency, higher accuracy and better universality qualities. Simulation results verified the superiority and validity of the proposed algorithm when compared with original algorithms.

Open access

Xiao-ming Li, Jia-yue Yin, Hao-jun Xu, Chengqiong Bi, Li Zhu, Xiao-dong Deng and Lei-nan Ma

Open access

Chen-Yang Li, Yan-Hui Liu, Yu-Nan Ji, Ling-Li Xie and Zhen-Hua Hou

Abstract

Objective

This meta-analysis aims to evaluate the effects of traditional Chinese medicine (TCM) nursing combined with conventional nursing in patients with chronic obstructive pulmonary disease (COPD).

Methods

Data were collected from the databases of PubMed, Embase, the Cochrane Library, Web of Science, Google Scholar, China National Knowledge Infrastructure (CNKI), WanFang Data (WF) and VIP Database, including literature regarding the effects of TCM nursing combined with conventional nursing in patients with COPD published before January 2017. The Jadad scale was used to assess the quality of the eligible literature. The weighted mean differences and odds ratios were used to analyze St. George’s Respiratory Questionnaire (SGRQ) scores, pulmonary function, hospital stay, and clinical efficacy.

Results

Twenty-three randomized controlled trials comprising 3116 cases (TCM nursing combined with the conventional nursing group: 1559; conventional nursing group: 1557) met the inclusion criteria. TCM nursing combined with conventional nursing was associated with a lower SGRQ score, higher forced expiratory volume in 1 second (FEV1) value, higher FEV1/forced vital capacity (FVC) value, higher FEV1% value, higher FEV1 predicted value, shorter hospital stay, and preferable clinical efficacy.

Conclusions

TCM nursing combined with conventional nursing emphasized that dialectical nursing can be performed preferably in patients with COPD.

Open access

Xiaoxue Lian, Yan Li, Dongmin An, Yunling Zou, Qiong Wang and Nan Zhang

Abstract

In this study, we fabricated ZnO nanostructures using bamboo fibers as templates. The starting material used was zinc acetate, and the nanostructures were synthesized by soaking and calcining the bamboo fibers. The fabricated nanostructures were characterized using X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and ultraviolet-visible spectrophotometry. The results showed that the size of the ZnO nanoparticles was approximately 20–100 nm. When the ZnO nanoparticles were used as the catalyst in the photodegradation of methyl orange, the dye degraded by 95.98 % in 80 min. The response and recovery times of a gas sensor based on the ZnO nanoparticles were 25 and 24 s, respectively, during the detection of C2H5OH in a concentration of 10 ppm at 270 °C.

Open access

Bin Li, Xiaomeng Cui, Lucan Zhao, Le Wang, Guoyong Xie and Nan Deng

Summary

Establishing a realistic gas flow velocity distribution inside a cigarette filter during smoking is important to understand filtration mechanisms of different mainstream smoke species and the overall effect of filter designs on mainstream smoke composition. In this paper, an experimental method is described which directly measures the gas pressure field inside a cellulose acetate filter during cigarette smoking. This was demonstrated by using 3R4F research reference cigarettes smoked under a 35 mL puff of 6 s duration. In addition, filter temperature measurements were also carried out at multiple locations within the filter. Both the temperature and pressure sensing locations were selected to match the radial and longitudinal directions of the cigarette filter. The temperature and pressure measurements were then used to calculate the velocity according to Darcy’s Law along the mainstream flow direction in the cigarette filter at each puff. The spatially resolved maps of temperature, pressure and flow velocity on a puff-by-puff basis provide useful insights into the dynamic filtration of smoke aerosol under the influence of the approaching burning coal and progressive accumulation of smoke particulate matter.

Open access

Guang-Hou Zhou, Li Han, Zhen-Nan Fan, Yong Liao and Song Huang

Abstract

To study the principle of loss and heat at the end region of large 4-poles nuclear power turbine generator, 3D transient electromagnetic field and 3D steady temperature field finite element (FE) models of the end region are established respectively. Considering the factors such as rotor motion, core non-linearity and time-varying of electromagnetic field, the anisotropic heat conductivity and different heat dissipation conditions of stator end region, a 50 Hz, 1150 MW, 4-poles nuclear power turbine generator is investigated. The loss and heat at the generator end region are calculated respectively at no-load and rated-load, and the calculation results are compared with the test data. The result shows that the calculation model is accurate and the generator design is suitable. The method is valuable for the research of loss and heat at the end region of large 4-poles nuclear power turbine generator and the improvement of the generator’s operation stability. The method has been applied successfully for the design of the larger nuclear power turbine generators