Search Results

1 - 7 of 7 items

  • Author: Ke Zhang x
Clear All Modify Search
The effect of preparation method on the performance of PtSn/Al2O3 catalysts for acetic acid hydrogenation

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
Blade Tip-timing Technology with Multiple Reference Phases for Online Monitoring of High-speed Blades under Variable-speed Operation

Abstract

High-speed blades form core mechanical components in turbomachines. Research concerning online monitoring of operating states of such blades has drawn increased attention in recent years. To this end, various methods have been devised, of which, the blade tip-timing (BTT) technique is considered the most promising. However, the traditional BTT method is only suitable for constant-speed operations. But in practice, the rotational speed of turbomachine blades is constantly changing under the influence of external factors, which lead to unacceptable errors in measurement. To tackle this problem, a new BTT method based on multi-phases is proposed. A plurality of phases was arranged as evenly as possible on the rotating shaft to determine the rotation speed. Meanwhile, the corresponding virtual reference point was determined in accordance with the number of blades between consecutive phases. Based on these reference points, equations to measure displacement due to blade vibrations were deduced. Finally, mathematical modeling, numerical simulation and experimental tests were performed to verify the validity of the proposed method. Results demonstrate that the error in measurement induced when using the proposed method is less than 1.8 %, which is much lower compared to traditional methods utilized under variable-speed operation.

Open access
Research On The Construction And Operation Mode Of College Student Entrepreneurship Alliance – Taking Hebei Province As An Example

Abstract

The construction and good operation of college student entrepreneurship organizations play an important role in the cultivation of college student entrepreneurship awareness and the improvement of college student entrepreneurship ability and success rate. This paper summarizes the factors restricting student entrepreneurship and proposes the suggestion of constructing student entrepreneurship alliance based on the analysis of the education and the current operation status of entrepreneurship organizations in Hebei Province. With the idea of “Promoting employment by entrepreneurship to realize social entrepreneurship” and the target of “Improving college student entrepreneurship success rate”, college student entrepreneurship alliance integrates multi social resources with the involvement of the government, society, enterprises and colleges. The operation of the alliance is divided into education stage, incubation stage and marketing operation stage. By the three stages’ cultivation to college students, it plays a positive role in aspects such as the participation of college education and social education, the promotion of entrepreneurship education development and college student entrepreneurship success rate and district economic development.

Open access
Self-esteem enhancement as a strategy for promoting the mental health and averting the occupational problems of nurses

Abstract

In recent years, shortage of nurses, high turnover rate, low self-worth, and team instability have become increasingly serious. With the development of positive psychology, more and more nursing managers have begun to attach great importance to the mental health of nurses. Self-esteem, as one of the core indicators of individual mental health, has received extensive attention from researchers in different fields since its inception. This paper reviews and summarizes the research status and development trends of nurses’ self-esteem considering the aspects of self-esteem as a concept, assessment tools, significance, and intervention methods. At the same time, it also puts forward problems that need to be solved by undertaking research into nurses’ self-esteem, in order to provide a reference for further studies on nurses’ self-esteem.

Open access
Reliability Based Analysis and Design of a Tripod Offshore Wind Turbine Structure Assuring Serviceability Performance

Abstract

Typical tripod foundations are designed using deterministic computational models according to relevant standards and codes. However, for more cost-safety balanced design, uncertainties in significant parameters should be considered in preliminary design to ensure meeting a specific probabilistic safety target in the context of the complex configuration of a tripod structure. In this article, uncertainties associated with design parameters and modelling errors are considered using Monte Carlo simulations, in order to determine the key structural design parameters, and to determine the optimal balance between design parameters and design requirements. A Spearman rank-order correlation based analysis is carried out to understand the effects of design variables on maximum deformation, total weight, and natural frequency, and to have insight about important design parameters for improvement of a preliminary design. It is found that the tower diameter has the most significant effect on the maximum displacement on the hub as validated through engineering case studies. In addition, a statistical framework, which identifies influential design parameters and provides reliability evaluation, is proposed for the structural design of a tripod OWT system. The design cases considered in this study indicate that a simple deterministic design check cannot guarantee the required reliability level of the structure, and the cost-safety balance can be achieved by a reliability analysis with the consideration of the uncertainties in the structure.

Open access
A Report on Multilinear PCA Plus GTDA to Deal With Face Image

Abstract

Because face images are naturally two-dimensional data, there have been several 2D feature extraction methods to deal with facial images while there are few 2D effective classifiers. Meanwhile, there is an increasing interest in the multilinear subspace analysis and many methods have been proposed to operate directly on these tensorial data during the past several years. One of these popular unsupervised multilinear algorithms is Multilinear Principal Component Analysis (MPCA) while another of the supervised multilinear algorithm is Multilinear Discriminant Analysis (MDA). Then a MPCA+MDA method has been introduced to deal with the tensorial signal. However, due to the no convergence of MDA, it is difficult for MPCA+MDA to obtain a precise result. Hence, to overcome this limitation, a new MPCA plus General Tensor Discriminant Analysis (GTDA) solution with well convergence is presented for tensorial face images feature extraction in this paper. Several experiments are carried out to evaluate the performance of MPCA+GTDA on different databases and the results show that this method has the potential to achieve comparative effect as MPCA+MDA.

Open access
The Comparative Study on Two Models of Syndrome Differentiation of the Hand, Foot and Mouth Disease: An Investigation Analysis of the Signs and Symptoms on 2 325 Cases

Abstract

Objective To realize the characteristics of “zheng” differentiation-treatment for hand, foot and mouth disease (HFMD), a new methodology of syndrome differentiation for different stages of HFMD has been explored.

Methods Total of 2 325 cases with HFMD were recorded by distributing them into exterior syndrome stage, interior syndrome stage, severe syndrome stage and recovered syndrome stage, respectively, and the main symptoms and subsidiary symptoms of different stages of HFMD have been observed. The major and minor pathogenesis of HFMD in different stages were obtained, and compared with the “2010 Guideline for the Diagnosis and Treatment of HFMD”.

Results It was found that the major pathogenesis of exterior stage was defined as “the invation of the wenevil to the defender of the body with the collaterals got involved”, and the minor as “qi deficiency”; in interior stage, “the fury of Gan-Yang” was the main pathogenesis, and “qi in chaos and qi deficiency” was the minor; in severe syndrome stage, “the damage of heart, liver and lung” was the main pathogenesis, and “qi in chaos” was the minor; and the pathogenesis of recovered stage was “qi-yin deficiency”. Compared with the “2010 Guideline for the Diagnosis and Treatment of HFMD”, it showed that “the obstruction of the fei-pi qi by the mixture of shi-re evil” and “the mixture of shi-re” in vivo was quite difficult to be explained in completely different context in the general situation; in the severe stage, the TCM clinical characteristics of syndrome differentiation might lose; in the early acute severe cases, the phenomenon that xin-yang and fei-qi almost ran out was difficult to be observed, then, the line between the severe and the acute severe became vague.

Conclusions The theory of syndrome differentiation by stages of HFMD was reasonable in the actual situation of clinical description on HFMD which was expected to be further tested and widely applied in the “zheng” differentiation-treatment of HFMD in the future.

Open access