Xu Han, Zhonghe Han, Wei Zeng, Peng Li and Jiangbo Qian
The purpose of this paper is to study the condensation flow of wet steam in the last stage of a steam turbine and to obtain the distribution of condensation parameters such as…
Abstract
Purpose
The purpose of this paper is to study the condensation flow of wet steam in the last stage of a steam turbine and to obtain the distribution of condensation parameters such as nucleation rate, Mach number and wetness.
Design/methodology/approach
Because of the sensitivity of the condensation parameter distribution, a double fluid numerical model and a realizable k-ε-kd turbulence model were applied in this study, and the numerical solution for the non-equilibrium condensation flow is provided.
Findings
The simulation results are consistent with the experimental results of the Bakhtar test. The calculation results indicate that the degree of departure from saturation has a significant impact on the wet steam transonic condensation flow. When the inlet steam deviates from the saturation state, shock wave interference and vortex mixing also have a great influence on the distribution of water droplets.
Originality/value
The research results can provide reference for steam turbine wetness losses evaluation and flow passage structure optimization design.
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Xu Han, Wei Zeng and Zhonghe Han
The purpose of this study is to improved the efficiency of condensing steam turbines by legitimately reforming the flow structure. It is of great significance to study the…
Abstract
Purpose
The purpose of this study is to improved the efficiency of condensing steam turbines by legitimately reforming the flow structure. It is of great significance to study the condensation flow characteristics of wet steam for optimizing the operation of condensing steam turbines.
Design/methodology/approach
A two-fluid model was used to study the wet steam flow in a stator cascade. The effects of the inlet temperature and pressure drop on the cascade performance were analyzed. On this basis, endwall protrusion models were set up at varied axial position on the pressure surface to evaluate the wetness control and loss under different design conditions for cascade optimization.
Findings
The analysis indicates that increasing the inlet temperature or decreasing the pressure drop can effectively control the steam wetness but increase the droplet radius. The increasing inlet temperature can delay the condensation and alleviate the deterioration of the aerodynamic performance of cascades. The non-axisymmetric endwall can significantly affect the distribution of steam parameters below its height and slightly reduce the droplet radius. Compared with the original stator cascade, the optimum design conditions reduce the steam wetness by 8.07 per cent and the total pressure loss by 6.91 per cent below a 20 per cent blade height.
Originality/value
These research results can serve as a reference for condensing steam turbine wetness losses evaluation and flow passage optimization design.
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Lydia Bals, Heather Berry, Evi Hartmann and Gordian Raettich
In this chapter, we embrace the recent phenomenon of early internationalizing firms with the goal of understanding these firms in light of decades of research on multinational…
Abstract
In this chapter, we embrace the recent phenomenon of early internationalizing firms with the goal of understanding these firms in light of decades of research on multinational firms, which has long stressed liabilities of foreignness. It is often implicitly assumed that the only way to reduce liabilities of foreignness is by doing business in foreign markets and learning about the local business environment. However, in this chapter, we focus on several distinctive antecedent firm characteristics that have been shown to facilitate early international expansion by firms, but which are not commonly considered in the international business literature. We perform a systematic review of the literature on early internationalizing firms (following David & Han, 2004), based on the seminal work of Oviatt and McDougall (1994) to guide our analysis of early internationalizing firms and to identify important ways in which these firms differ from multinational firms. We argue that long-standing arguments about the impact of liabilities of foreignness on firm foreign expansion apply to newly internationalizing firms, but that these liabilities are reduced by the experiences and knowledge of the founders and top managers in these firms acquired prior to the inception of these firms.
Xu Han, Xiangyu Liu, Yunyun Yuan and Zhonghe Han
The flow state of wet steam will affect the thermodynamic and aerodynamic characteristics of steam turbine. The purpose of this study is to effectively control the wetness losses…
Abstract
Purpose
The flow state of wet steam will affect the thermodynamic and aerodynamic characteristics of steam turbine. The purpose of this study is to effectively control the wetness losses caused by wet steam condensation, and hence a cascade of 600 MW steam turbine was taken as the research object.
Design/methodology/approach
The influence of blade surface roughness on the condensation characteristics was analyzed, and the dehumidification mechanism and wetness control effect were obtained.
Findings
With the increase of blade surface roughness, the peak nucleation rate decreases gradually. According to the Mach number distribution on the blade surface, there is a sensitive region for the influence of roughness on the aerodynamic performance of cascade. The sensitive region of nucleation rate roughness should be between 50 and 150 µm.
Originality/value
The increase of blade surface roughness will increase the dynamic loss in cascade, but it can reduce the thermodynamic loss caused by condensation to a certain extent.
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Abstract
Purpose
The purpose of this paper is to investigate the effect of high-intensity pulsed ion beam (HIPIB) intensity on the structure and corrosive properties of microarc oxidation (MAO) films on AZ31 magnesium alloy and explore the mechanism for modified anti-corrosion properties of irradiated films.
Design/methodology/approach
The energy deposited on the coating surface influences the remelting process of the MAO coatings significantly, which was closely related to the intensity of HIPIB; therefore, HIPIB with various intensities of 100-350 A/cm2, was selected to modify the MAO films on AZ31 magnesium alloy. The changes in film structure and phase structure of modified films were characterized by scanning electron microscopy and X-ray diffractometry (XRD) with CuKα, respectively. The corrosive behavior of the MAO films was featured with polarization curves and electrochemical impedance spectrum in 3.5 per cent NaCl solution on a PAR 2273 electrochemical workstation.
Findings
The results clearly show that a dense, continual and remelted layer with a few micrometers in thickness was obtained on the irradiated surface at 200 A/cm2, which are mainly responsible for the modified and optimal anti-corrosion property of MAO films by suppressing/retarding the process of the corrosive electrolyte infiltration into magnesium substrate surface.
Originality/value
The paper reveals that HIPIB irradiation could modify the corrosion resistance by producing a remelted compact layer on the MAO film surface at a suitable irradiation parameter and explored the modified mechanism of MAO films.
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Keqing Li, Xiaojia Wang, Changyong Liang and Wenxing Lu
The elderly service industry is emerging in China. The Chinese government introduced a series of policies to guide elderly service enterprises to improve their service quality…
Abstract
Purpose
The elderly service industry is emerging in China. The Chinese government introduced a series of policies to guide elderly service enterprises to improve their service quality. This study explores novel differentiated subsidy strategies that not only promote the improvement of service quality in elderly service enterprises but also alleviate the financial burden on the government.
Design/methodology/approach
Evolutionary game and Hotelling models are employed to investigate this issue. First, a Hotelling model that considers consumer word-of-mouth preferences is established. Subsequently, an evolutionary game model between local governments and enterprises is constructed, and the evolutionary stable strategies of both parties are analyzed. Finally, simulation experiments are conducted.
Findings
The findings indicate that local government decisions have a significant influence on the behavior of elderly service enterprises. Increasing the proportion of local governments opting for subsidy strategies helps incentivize elderly service enterprises to improve their service quality. Furthermore, providing differentiated subsidies based on the preferences of the customer base of elderly service enterprises can encourage service quality improvement while reducing government expenditure. The findings offer valuable insights into the design of government subsidy policies.
Originality/value
Compared with previous research, this study examines the role of consumer preferences in a differentiated subsidy policy. This enriches the authors’ understanding of the field by incorporating neglected aspects of consumer preferences in the context of the emerging elderly service industry.
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Xiaoliang Qian, Jing Li, Jianwei Zhang, Wenhao Zhang, Weichao Yue, Qing-E Wu, Huanlong Zhang, Yuanyuan Wu and Wei Wang
An effective machine vision-based method for micro-crack detection of solar cell can economically improve the qualified rate of solar cells. However, how to extract features which…
Abstract
Purpose
An effective machine vision-based method for micro-crack detection of solar cell can economically improve the qualified rate of solar cells. However, how to extract features which have strong generalization and data representation ability at the same time is still an open problem for machine vision-based methods.
Design/methodology/approach
A micro-crack detection method based on adaptive deep features and visual saliency is proposed in this paper. The proposed method can adaptively extract deep features from the input image without any supervised training. Furthermore, considering the fact that micro-cracks can obviously attract visual attention when people look at the solar cell’s surface, the visual saliency is also introduced for the micro-crack detection.
Findings
Comprehensive evaluations are implemented on two existing data sets, where subjective experimental results show that most of the micro-cracks can be detected, and the objective experimental results show that the method proposed in this study has better performance in detecting precision.
Originality/value
First, an adaptive deep features extraction scheme without any supervised training is proposed for micro-crack detection. Second, the visual saliency is introduced for micro-crack detection.
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Abstract
Purpose
This study aims to explore the spatio-temporal dynamic characteristics and influencing factors of the coordination degree of the three systems of digital economy, energy and human habitat in Western China and to provide academic research support for promoting coordinated and sustainable development in similar regions of the world.
Design/methodology/approach
Based on system theory and sustainable development theory, this study primarily uses the coupled coordination degree model to assess the degree of coordination between the three systems.
Findings
The findings of this study indicate that: The three systems’ overall coordination is low. The distribution of the degree of coordination has spatial differences and its coefficient of variation is small. The probability of the coordination type changing for the better is greater than that of the opposite, and neighboring provinces interact with one another. The old-age dependence ratio, the resident population’s urbanization rate and public budget expenditure have the strongest gray association with the degree of coordination.
Practical implications
This study’s findings will be valuable for policymakers in developing policies to promote the coordinated and sustainable growth of the region’s digital economy, energy and human habitat. Additionally, the findings will aid in facilitating regional exchanges and cooperation to enhance the level of sustainable development.
Social implications
This study’s findings will contribute to increased social interest in coordinating sustainable growth in the digital economy, energy and human habitat.
Originality/value
This study examines the digital economy, energy and human habitat within the same framework and investigates spatial spillover effects using spatial Markov chains.
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Yue Wang, Han Zhao, Haiyue Yang and Xiangshuai Song
The visible time window (VTW) calculation of satellites to ground targets is significant for Earth observation satellites' operation management and control. With the improvement…
Abstract
Purpose
The visible time window (VTW) calculation of satellites to ground targets is significant for Earth observation satellites' operation management and control. With the improvement of satellite maneuvering capability and the complexity of on-orbit observation tasks, the traditional VTW calculation methods can no longer meet the demands of satellite operation management and control due to a large amount of calculation and low efficiency. The purpose of this study is to propose a fast VTW calculation method based on map segmentation named map segmentation method (MSM), to improve the calculation efficiency, and further solve this problem.
Design/methodology/approach
The main feature of the MSM method is to segment the map and subsatellite trajectories and traverse the subsatellite points within a specific range around the target, significantly reducing the search space and the amount of computation and improving computational efficiency.
Findings
Numerical simulations for two satellite orbits are implemented to verify the feasibility of the proposed VTW calculation method, and the traditional traversal method (TM) is also performed for comparative analysis. The results show that the proposed method can obtain the same VTW, using less calculation time than the TM. The computational efficiency is significantly improved, especially for many tasks. The calculation time of observing 500 targets is saved by more than 70%, indicating a broad application prospect.
Originality/value
This paper proposes an original VTW calculation method based on map segmentation to improve the calculation efficiency. The simulation scenarios are designed to verify the accuracy and effectiveness of the proposed method, and the observation targets are randomly distributed on the map. For comparative analysis, the TM is also performed under the same simulation conditions.
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You-De Dai, Giun-Ting Yeh, Tsungpo Tsai, Yi-Chun Chen and Yuan-Chiu Chen
This study develops a structural model to examine the relationships among subjective perception of health, subjective perception of economic and social support, the perceived…
Abstract
This study develops a structural model to examine the relationships among subjective perception of health, subjective perception of economic and social support, the perceived freedom in leisure, leisure satisfaction, and the well-being of elders. The subject of this study is the elderly who participated in leisure activities at Evergreen Academy in Kaohsiung City. Convenience sampling and quota sampling are adopted. 1,200 self-administered questionnaires are distributed, and 535 are valid, with a response rate of 45%. The results of this study show that subjective perception of health will positively affect perceived freedom in leisure; subjective perception of economics will positively affect perceived freedom in leisure and well-being; social support will positively affect perceived freedom in leisure, leisure satisfaction, and well-being; perceived freedom in leisure will positively affect leisure satisfaction and well-being; leisure satisfaction will positively affect well-being. There are significant differences in the subjective perception of economic and social support between male and female elders. There are significant differences in the subjective perception of economic, leisure satisfaction, and well-being among those with different education levels.