Hongbin Liu, Xinrong Su and Xin Yuan
Adopting large eddy simulation (LES) to simulate the complex flow in turbomachinery is appropriate to overcome the limitation of current Reynolds-Averaged Navier–Stokes modelling…
Abstract
Purpose
Adopting large eddy simulation (LES) to simulate the complex flow in turbomachinery is appropriate to overcome the limitation of current Reynolds-Averaged Navier–Stokes modelling and it provides a deeper understanding of the complicated transitional and turbulent flow mechanism; however, the large computational cost limits its application in high Reynolds number flow. This study aims to develop a three-dimensional GPU-enabled parallel-unstructured solver to speed up the high-fidelity LES simulation.
Design/methodology/approach
Compared to the central processing units (CPUs), graphics processing units (GPUs) can provide higher computational speed. This work aims to develop a three-dimensional GPU-enabled parallel-unstructured solver to speed up the high-fidelity LES simulation. A set of low-dissipation schemes designed for unstructured mesh is implemented with compute unified device architecture programming model. Several key parameters affecting the performance of the GPU code are discussed and further speed-up can be obtained by analysing the underlying finite volume-based numerical scheme.
Findings
The results show that an acceleration ratio of approximately 84 (on a single GPU) for double precision algorithm can be achieved with this unstructured GPU code. The transitional flow inside a compressor is simulated and the computational efficiency has been improved greatly. The transition process is discussed and the role of K-H instability playing in the transition mechanism is verified.
Practical/implications
The speed-up gained from GPU-enabled solver reaches 84 compared to original code running on CPU and the vast speed-up enables the fast-turnaround high-fidelity LES simulation.
Originality/value
The GPU-enabled flow solver is implemented and optimized according to the feature of finite volume scheme. The solving time is reduced remarkably and the detail structures including vortices are captured.
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Keywords
Yi-Kang Liu, Xin-Yuan Liu, E. Deng, Yi-Qing Ni and Huan Yue
This study aims to propose a series of numerical and surrogate models to investigate the aerodynamic pressure inside cracks in high-speed railway tunnel linings and to predict the…
Abstract
Purpose
This study aims to propose a series of numerical and surrogate models to investigate the aerodynamic pressure inside cracks in high-speed railway tunnel linings and to predict the stress intensity factors (SIFs) at the crack tip.
Design/methodology/approach
A computational fluid dynamics (CFD) model is used to calculate the aerodynamic pressure exerted on two cracked surfaces. The simulation uses the viscous unsteady κ-ε turbulence model. Using this CFD model, the spatial and temporal distribution of aerodynamic pressure inside longitudinal, oblique and circumferential cracks are analyzed. The mechanism behind the pressure variation in tunnel lining cracks is revealed by the air density field. Furthermore, a response surface model (RSM) is proposed to predict the maximum SIF at the crack tip of circumferential cracks and analyze its influential parameters.
Findings
The initial compression wave amplifies and oscillates in cracks in tunnel linings, resulting from an increase in air density at the crack front. The maximum pressure in the circumferential crack is 2.27 and 1.76 times higher than that in the longitudinal and oblique cracks, respectively. The RSM accurately predicts the SIF at the crack tip of circumferential cracks. The SIF at the crack tip is most affected by variations in train velocities, followed by the depth and length of the cracks.
Originality/value
The mechanism behind the variation of aerodynamic pressure in tunnel lining cracks is revealed. In addition, a reliable surrogate model is proposed to predict the mechanical response of the crack tip under aerodynamic pressures.
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Yingtan Mu and Xin Yuan
At the end of the 1970s, the Chinese government enacted the one-child policy; now the one-child successively enters into the labor market and reaches the age for marriage and…
Abstract
Purpose
At the end of the 1970s, the Chinese government enacted the one-child policy; now the one-child successively enters into the labor market and reaches the age for marriage and childbirth. The floating population group of China’s interior regions also experiences the heterogeneity changes. The purpose of this paper is to analyses the reasons for the difference of family migration between one-child and non-only child using the binary logit regression model – from the three aspects of individual characteristics, family endowment and institutional factors were investigated.
Design/methodology/approach
Family migration or individual migration of the floating population is the dichotomous dependent variable and therefore the binomial logistic regression analysis model is selected.
Findings
It is found that the tendency of one-child family migration is significantly higher than that of non-only child. The main reason is that the one-child has obvious advantages in terms of individual characteristics, family endowment and institutional factors.
Originality/value
The previous researches on family migration: first, the previous researches mainly analyzed the impact of the human capital and family income on the family migration from the perspective of economics and neglected the discussion on the family structure, life cycle, family level factors and Hukou’s limitation; second, most researches considered the migration as a whole. In fact, the migration population is no longer a highly homogeneous group and gradually become diversified.
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Waheed Ur Rehman, Jiang Guiyun, Luo Yuan Xin, Wang Yongqin, Nadeem Iqbal, Shafiq UrRehman and Shamsa Bibi
This paper’s aim is modeling and simulation of an advanced controller design for a novel mechatronics system that consists of a hydrostatic journal bearing with servo control. The…
Abstract
Purpose
This paper’s aim is modeling and simulation of an advanced controller design for a novel mechatronics system that consists of a hydrostatic journal bearing with servo control. The proposed mechatronic system has more worth in tribology applications as compared to the traditional hydrostatic bearing which has limited efficiency and poor performance because of lower stiffness and load-carrying capacity. The proposed mechatronic system takes advantage of active lubrication to improve stiffness, rotor’s stability and load-carrying capacity.
Design/methodology/approach
The current work proposes extended state observer-based controller to control the active lubrication for hydrostatic journal bearing. The advantage of using observer is to estimate unknown state variables and lumped effects because of unmodeled dynamics, model uncertainties, and unknown external disturbances. The effectiveness of the proposed mechatronic system is checked against the traditional hydrostatic bearing.
Findings
Proposed mechatronics active hydrostatic journal bearing system is checked against traditional hydrostatic journal bearing. It is found that novel active hydrostatic journal bearing with servo control has good tribology performance factors such as stiffness, less rotor vibration, no wear and friction under starting conditions and high load-carrying capacity under different conditions of spindle speed, temperature, initial oil pressure and external disturbance. The result shows that proposed mechatronics system has more worth in rotary tribology applications.
Originality/value
The current manuscript designs a novel active hydrostatic journal bearing system with servo control. The mathematical model has advantages in term of estimating unknown state variables and lumped effects because of unmodeled dynamics, model uncertainties and unknown external disturbances. The result shows improvement in dynamic characteristics of a hydrostatic journal bearing under different dynamic conditions.
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Terence Y.M. Lam and Junjie Yan
Shanghai is currently faced with a rapid increase in the ageing population and demand for elderly homes. Continuing care retirement community (CCRC) has been emerging as a…
Abstract
Purpose
Shanghai is currently faced with a rapid increase in the ageing population and demand for elderly homes. Continuing care retirement community (CCRC) has been emerging as a high-end alternative to offer specialised accommodation to the elderly in major cities. Since the first development in 2008, the industry is now still at the infancy stage. This study aims to examine the investment barriers hindering the supply and demand of CCRCs with an aim to recommend practical and senior housing policy measures to facilitate CCRC developments.
Design/methodology/approach
Multiple-case study method was used to confirm whether the literature findings on investment barriers apply to the context of Shanghai. Four representative CCRC development cases in Shanghai were examined, in which qualitative data were collected from interviews with experienced CCRC development managers and quantitative data from a questionnaire survey of the CCRC residents.
Findings
Operation management experience, financial risks and government support policy were found to be the main supply barriers. Chinese traditional family-oriented culture and affordability were not the main demand barriers of CCRCs in Shanghai. Poor quality of services and living environment were identified as the main barriers suppressing the demand for CCRC.
Research limitations/implications
Although common trends and views can be drawn from the representative cases in Shanghai to provide valid results, further research should be conducted on other major cities in China so that the results can be widely applied.
Practical implications
Successful CCRC investment strategy should focus on partnering with experienced professional eldercare management companies, provisions of high-quality medical professionals and trained care personnel and delivery of flexible care service, along with intensive capital flows for land, construction and operating costs.
Social implications
Additional senior housing policy support should be established to promote the CCRC supply to address the ageing needs, particularly granting lands for CCRC developments at Tiers 1 and 2 major cities where the land cost is high.
Originality/value
This research’s practical and policy measures can be applied to enable and promote CCRC developments in Shanghai, thus benefitting both housing investors and the government. The findings also form a baseline for CCRC developments in other major cities.
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Knowledge input development and innovation implementation are new features of industrial technology innovation. The purpose of this study is to find the process of coordination…
Abstract
Purpose
Knowledge input development and innovation implementation are new features of industrial technology innovation. The purpose of this study is to find the process of coordination and ecological spiral in the ambidextrous innovation of industrial technology.
Design/methodology/approach
To design the model of industrial technology ambidextrous innovation based on knowledge ecology spiral, an input-output model of knowledge for ambidextrous innovation and a spiral model of knowledge ecology were constructed based on an improved Lotka-Volterra model. Then, the equilibriums in different knowledge inputs and the spiral evolution of knowledge ecology were analyzed. Finally, the ambidextrous coordination mechanism of the core organization was revealed.
Findings
By coordinating the knowledge inputs and the knowledge ecology spiral, enterprises extend the R&D investments in the innovation chain, which will facilitate the knowledge inputs of the exploitative and exploratory innovation. Implementing the ambidextrous coordination in the technology innovation chain and the knowledge ecology chain has the advantage of promoting knowledge inputs, mobility and ecological spiral. Meanwhile, it can achieve the “multi-source, integration and coordination” development of industrial technology innovation.
Originality/value
The two-element innovative knowledge input coordination model and the knowledge ecological spiral model based on the improved Lotka-Volterra model are constructed, which extends the modeling way of the traditional knowledge input-output profit model. It is expected to reduce the amount of knowledge input of a single member and provide theoretical reference for improving the efficiency of knowledge input by constructing the inter-dependent regenerative and inter-generative knowledge interaction.
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Xufan Zhang, Xue Fan and Mingke He
The challenges faced by China's high-end equipment manufacturing (HEEM) industry are becoming clearer in the process of global supply chain (GSC) reconfiguration. The purpose of…
Abstract
Purpose
The challenges faced by China's high-end equipment manufacturing (HEEM) industry are becoming clearer in the process of global supply chain (GSC) reconfiguration. The purpose of this study is to investigate how China's HEEM industry has been affected by the GSC reconfiguration, as well as its short- and long-term strategies.
Design/methodology/approach
The authors adopted a multi-method approach. Interviews were conducted in Phase 1, while a three-round Delphi survey was conducted in Phase 2 to reach consensus at the industry level.
Findings
The GSC reconfiguration affected China's HEEM supply chain (SC). Its direct effects include longer lead times, higher purchasing prices and inconsistent supply and inventory levels of key imported components and materials. Its indirect effects include inconsistent product quality and cash flows. In the short term, China's HEEM enterprises have sought to employ localized substitutes, while long-term strategies include continuous technological innovation, industry upgrades and developing SC resilience.
Originality/value
This study not only encourages Chinese HEEM enterprises to undertake a comprehensive examination of their respective industries but also provides practical insights for SC scholars, policymakers and international stakeholders interested in how China's HEEM industry adapts to the GSC reconfiguration and gains global market share.
Details
Keywords
CHINA: Record low birth rate hastens depopulation
Details
DOI: 10.1108/OXAN-ES265664
ISSN: 2633-304X
Keywords
Geographic
Topical
Meng-Nan Li, Xueqing Wang, Ruo-Xing Cheng and Yuan Chen
Currently, engineering project design lacks a design framework that fully combines subjective experience and objective data. This study develops an aided design decision-making…
Abstract
Purpose
Currently, engineering project design lacks a design framework that fully combines subjective experience and objective data. This study develops an aided design decision-making framework to automatically output the optimal design alternative for engineering projects in a more efficient and objective mode, which synthesizes the design experience.
Design/methodology/approach
A database of design components is first constructed to facilitate the retrieval of data and the design alternative screening algorithm is proposed to automatically select all feasible design alternatives. Then back propagation (BP) neural network algorithm is introduced to predict the cost of all feasible design alternatives. Based on the gray relational degree-particle swarm optimization (GRD-PSO) algorithm, the optimal design alternative can be selected considering multiple objectives.
Findings
The case study shows that the BP neural network-cost prediction algorithm can well predict the cost of design alternatives, and the framework can be widely used at the design stage of most engineering projects. Design components with low sensitivity to design objectives have been obtained, allowing for the consideration of disregarding their impacts on design objectives in such situations requiring rapid decisions. Meanwhile, design components with high sensitivity to design objective weights have also been obtained, drawing special attention to the effects of changes in the importance of design objectives on the selection of these components. Simultaneously, the framework can be flexibly adjusted to different design objectives and identify key design components, providing decision reference for designers.
Originality/value
The framework proposed in this paper contributes to the knowledge of design decision-making by emphasizing the importance of combining objective data and subjective experience, whose significance is ignored in the existing literature.
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Keywords
Shuxin Ding, Tao Zhang, Kai Sheng, Yuanyuan Chen and Zhiming Yuan
The intelligent Central Traffic Control (CTC) system plays a vital role in establishing an intelligent high-speed railway (HSR) system. As the core of HSR transportation command…
Abstract
Purpose
The intelligent Central Traffic Control (CTC) system plays a vital role in establishing an intelligent high-speed railway (HSR) system. As the core of HSR transportation command, the intelligent CTC system is a new HSR dispatching command system that integrates the widely used CTC in China with the practical service requirements of intelligent dispatching. This paper aims to propose key technologies and applications for intelligent dispatching command in HSR in China.
Design/methodology/approach
This paper first briefly introduces the functions and configuration of the intelligent CTC system. Some new servers, terminals and interfaces are introduced, which are plan adjustment server/terminal, interface for automatic train operation (ATO), interface for Dynamic Monitoring System of Train Control Equipment (DMS), interface for Power Supervisory Control and Data Acquisition (PSCADA), interface for Disaster Monitoring, etc.
Findings
The key technologies applied in the intelligent CTC system include automatic adjustment of train operation plans, safety control of train routes and commands, traffic information data platform, integrated simulation of traffic dispatching and ATO function. These technologies have been applied in the Beijing-Zhangjiakou HSR, which commenced operations at the end of 2019. Implementing these key intelligent functions has improved the train dispatching command capacity, ensured the safe operation of intelligent HSR, reduced the labor intensity of dispatching operators and enhanced the intelligence level of China's dispatching system.
Originality/value
This paper provides further challenges and research directions for the intelligent dispatching command of HSR. To achieve the objectives, new measures need to be conducted, including the development of advanced technologies for intelligent dispatching command, coping with new requirements with the development of China's railway signaling system, the integration of traffic dispatching and train control and the application of AI and data-driven modeling and methods.