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Kun Lei, Hongfang Ma, Haitao Zhang, Weiyong Ying and Dingye Fang

Abstract

The present work was a study on global reaction rate of methanol synthesis. We measured experimentally the global reaction rate in the internal recycle gradientless reactor over catalyst SC309. The diffusion-reaction model of methanol synthesis was suggested. For model we chose the hydrogenation of CO and CO2 as key reaction. CO and CO2 were key components in our model. The internal diffusion effectiveness factors of CO and CO2 in the catalyst were calculated by the numerical integration. A comparison with the experiment showed that all the absolute values of the relative error were less than 10%. The simulation results showed that decreasing reaction temperature and catalyst diameter were conducive to reduce the influence of the internal diffusion on the methanol synthesis.

Open access

Ding Zhu, Chao Zhang, Huahao Shen and Songmin Ying

Open access

Ying Zhang, Chengjun Qiu, You Li, Wenlong Zhang and Wang Xuan

Abstract

A new type of electro-optic (EO) polymer is prepared in this work. The main chain of the EO polymer is made of polyphosphazenes, and the side chain consists of carbazole based nitro azobenzene. The principle and method of preparation are given and the characteristics of this material are studied in details. The polymer with an EO coefficient of 35 pm/V has fine stability and can be easily processed. It also shows photoconductivity due to the carbazole group. This polymer thin film is obtained through performance improvement. Terahertz (THz) wave can be detected using the device, which is made of the new polymer. Owing to its fascinating properties, this new type of EO polymer has the potential to be widely applied in photorefractive materials as well as for emission and detection of THz radiation.

Open access

Ke Zhang, Haitao Zhang, Hongfang Ma, Weiyong Ying and Dingye Fang

Abstract

PtSn/Al2O3 catalysts with a given loading of 1 wt% Pt and 1 wt% Sn were prepared by co-impregnation or successive impregnation with aqueous solutions of Pt, Sn precursors and a commercial alumina. The catalysts were characterized by N2 adsorption, H2-TPR (H2 temperature-programmed reduction), H2-pulse chemisorption, XPS (X-ray photoelectron spectroscopy) and CO-FTIR (Fourier transform infrared spectroscopy), and tested in the hydrogenation of acetic acid. The results showed that the preparation method affected both the chemical properties and their performance in the hydrogenation of acetic acid. Sn enrichment on the catalysts surface was observed on the co-impregnated catalyst and catalyst in which the Pt precursor had been loaded first. It was found that the modification of Pt was a function of the sequence of Sn addition as revealed by CO-FTIR. Co-impregnated catalyst showed the highest activity and ethanol selectivity.

Open access

Yue-qiu Zhang, Shao-xia Xu, Sai-nan Bian, Li-fan Zhang, Yao Zhang, Wei-hong Zhang, Ying-chun Xu and Xiao-qing Liu

Abstract

Objective To investigate the infection rate of hepatitis C virus among the ambulatory patients and in-patients of a tertiary teaching hospital, and study the demographic factors related to the prevalence of hepatitis C virus infection.

Methods All patients tested for hepatitis C virus antibody from July 2008 to July 2009 in Peking Union Medical College Hospital were enrolled in this cross-sectional analysis. The prevalence of hepatitis C virus infection was compared according to age, gender, and departments, respectively. Among patients with positive serology hepatitis C virus marker, the positivity of hepatitis C virus RNA was analysed.

Results Among 29 896 subjects included, the hepatitis C virus antibody of 494 patients were positive (1.7%). When patients were divided into 9 age groups, the age specific prevalence of hepatitis C virus antibody were 0.2%, 1.7%, 1.2%, 1.1%, 1.5%, 1.9%,2.6%, 2.4% and 2%, respectively. The prevalence of hepatitis C virus antibody in non-surgical department and surgical department was 3% and 1%, respectively. The prevalence of hepatitis C virus antibody of males was higher than that of the females. Total of 194 patients with positive hepatitis C virus antibody were tested for hepatitis C virus RNA, the RNA level of 113 patients (58.2%) were higher than the low detection limit.

Conclusions The prevalence of hepatitis C virus antibody was relatively high among patients of general tertiary hospital. Age group of 60-69, males and patients in non-surgical departments were factors associated with high rate of hepatitis C virus infection.

Open access

Lan Gao, Xiu-Zhen Cao, Ying Zhang, Tai-Fang Liu and Ai-Hua Zhang

Abstract

Objective

To analyze the literature status and research hotspots of Science Citation Index (SCI)-related ostomy in the world and to provide references for scientific research and clinical work in the stoma care field.

Methods

Based on the Web of Science core database and its own analysis function, HistCite analysis software and Excel were used to study the published research about ostomy patients.

Results

A total of 1,262 articles were published between 1910 and 2016 with the authors from 48 countries and regions, 1,347 research institutions, published in 321 journals, with 4,048 first authors and coauthors; globally, there was a trend of slow growth in the number of authors every year. The study in the USA was absolutely in the lead position, and Canada and Turkey were more active. China's circulation volume was the 15th in the world. The periodical that published most often was the Journal of Wound Ostomy and Continence Nursing The most interdisciplinary surgical studies were surgery and nursing, where these should be considered important. The most prolific author in the field was "Grant", and the highest cited article was entitled as "Living with a stoma: a review of the literature".

Conclusions

The related research of global stoma is constantly developing. The research hotspot is nursing before and after stoma surgery. China and the USA are leading countries in research. They should follow the recent trend to improve the depth and breadth of the research in the field.

Open access

Ninga Sun, Ying-chaoa Zhang, Wei-guoa Zhang, En-lua Cheng and Yun-ping

Abstract

In order to effectively solve condensation and icing problems of radiosonde in low-temperature environment at high altitude, humidity sensor heated automatic alternately to remove pollution and improve the measurement accuracy. Heat experiments obtained the curve of rising temperature and responsible time on heated twin humidity sensor in normal temperature and pressure, by expanded responsible curve to obtain heated model of twin heated humidity sensor and by the analysis of heating model, use DMC and PID control for heating respectively. Simulation results show that the DMC control meets the practical requirements of measure at high altitude.

Open access

Ruirui Duan, Junmin Li, Yanni Zhang, Ying Yang and Guopei Chen

Abstract

This paper focuses on the problem of constraint control for a class of discrete-time nonlinear systems. Firstly, a new discrete T–S fuzzy hyperbolic model is proposed to represent a class of discrete-time nonlinear systems. By means of the parallel distributed compensation (PDC) method, a novel asymptotic stabilizing control law with the “soft” constraint property is designed. The main advantage is that the proposed control method may achieve a small control amplitude. Secondly, for an uncertain discrete T–S fuzzy hyperbolic system with external disturbances, by the proposed control method, the robust stability and H performance are developed by using a Lyapunov function, and some sufficient conditions are established through seeking feasible solutions of some linear matrix inequalities (LMIs) to obtain several positive diagonally dominant (PDD) matrices. Finally, the validity and feasibility of the proposed schemes are demonstrated by a numerical example and a Van de Vusse one, and some comparisons of the discrete T–S fuzzy hyperbolic model with the discrete T–S fuzzy linear one are also given to illustrate the advantage of our approach.

Open access

Guiyang Liu, Kong Xin, Lili Zhang, Baosen Wang and Ying He

Abstract

Spinel LiMn2O4 has been synthesized by a glycerol-assisted combustion synthesis method. The phase composition and morphologies of the compound were ascertained by X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical characterization was performed by using CR2032 coin-type cell. XRD analysis indicates that single phase spinel LiMn2O4 with good crystallinity has been obtained as a result of 5 h treatment at 600 °C. SEM investigation indicates that the average particle size of the sample is 200 nm. The initial discharge specific capacity of the LiMn2O4 is 123 mAh/g at a current density of 30 mA/g. When the current density increased to 300 mA/g, the LiMn2O4 offered a discharge specific capacity of 86 mAh/g. Compared with the LiMn2O4 prepared by a conventional solution combustion synthesis method at the same temperature, the prepared LiMn2O4 possesses higher purity, better crystallinity and more uniformly dispersed particles. Moreover, the initial discharge specific capacity, rate capability and cycling performance of the prepared LiMn2O4 are significantly improved.

Open access

Wen-Jiang Xiang, Zhi-Xiong Zhou, Dong-Yuan Ge, Qing-Ying Zhang and Qing-He Yao

A new approach based on hybrid Hopfield neural network and self-adaptive genetic algorithm for camera calibration is proposed. First, a Hopfield network based on dynamics is structured according to the normal equation obtained from experiment data. The network has 11 neurons, its weights are elements of the symmetrical matrix of the normal equation and keep invariable, whose input vector is corresponding to the right term of normal equation, and its output signals are corresponding to the fitting coefficients of the camera’s projection matrix. At the same time an innovative genetic algorithm is presented to get the global optimization solution, where the cross-over probability and mutation probability are tuned self-adaptively according to the evolution speed factor in longitudinal direction and the aggregation degree factor in lateral direction, respectively. When the system comes to global equilibrium state, the camera’s projection matrix is estimated from the output vector of the Hopfield network, so the camera calibration is completed. Finally, the precision analysis is carried out, which demonstrates that, as opposed to the existing methods, such as Faugeras’s, the proposed approach has high precision, and provides a new scheme for machine vision system and precision manufacture.