Abstract
Purpose
This paper aims to verify the inhibition of the hydrogen permeation effect of the coating and to quantitatively and qualitatively characterize the coating-induced stress.
Design/methodology/approach
By means of slow strain rate tensile testing (SSRT) in humid air, thickness measurement, fracture morphology, cross-section morphology and surface morphology, hydrogen content measurements, flow stress difference method.
Findings
The results demonstrate that the mechanism of the inhibition of hydrogen embrittlement by the coating is mainly attributed to the repression of hydrogen permeation and the additional coating-induced compressive stress.
Originality/value
It is proven that the micro-arc oxidation (MAO) coating does inhibit hydrogen entry into the alloy, and the stress induced by the MAO coating is compressive stress, which can restrain the hydrogen embrittlement of the alloy. Therefore, the mechanism of the inhibition of hydrogen embrittlement is dominated by the mechanisms of both hydrogen permeation inhibition and coating-induced stress.
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Abstract
Purpose
This paper aims to study the effect of Micro-arc oxidation (MAO) coating on stress corrosion and electrochemical behavior of aluminum alloy.
Design/methodology/approach
The stress corrosion cracking behavior of 7050 aluminum alloy (AA7050) after MAO treatment was investigated in 3.5 Wt.% NaCl solution using the constant load ring. Electrochemical impedance spectroscopy (EIS) was used to evaluate the change of corrosion resistance of MAO specimens in 3.5 Wt.% NaCl solution, and appropriate equivalent circuits were established.
Findings
The results demonstrated that the MAO coating can improve the corrosion resistance of the AA7050 and avoid the reduction of mechanical properties caused by corrosion. In the initial stage of corrosion, the corrosion resistance of coated specimen decreased at first and then increased. In the middle and final stage of corrosion, the corrosion resistance of coated specimen decreased at first and then stabilized.
Originality/value
The long-term corrosion behavior of MAO specimens under stress was studied by constant load experiment and EIS. It has guiding significance for the application of MAO technology on aluminum alloy.
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Abstract
Purpose
This paper aims to investigate the effects of different electrolyte systems on the properties of micro-arc oxidation coating on 7050 high strength aluminum alloy.
Design/methodology/approach
The coatings were prepared in silicate system with Na2SiO3 as main component, borate system with Na2B4O7 as main component and aluminate solution with Na2AlO2 as main salt, respectively.
Findings
The results show that the 7050 high strength aluminum alloy shows the best properties in silicate system.
Originality/value
This manuscript studied the crucial influence of different electrolyte systems on the microstructure and properties of the aluminum alloy micro-arc oxidation layer.
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Hannes Velt and Rudolf R. Sinkovics
This chapter offers a comprehensive review the literature on authentic leadership (AL). The authors employ a bibliometric approach to identify, classify, visualise and synthesise…
Abstract
This chapter offers a comprehensive review the literature on authentic leadership (AL). The authors employ a bibliometric approach to identify, classify, visualise and synthesise relevant scholarly publications and the work of a core group of interdisciplinary scholars who are key contributors to the research on AL. They review 264 journal articles, adopting a clustering technique to assess the central themes of AL scholarship. They identify five distinct thematic clusters: authenticity in the context of leadership; structure of AL; social perspectives on AL; dynamism of AL; and value perceptions of AL. Velt and Sinkovics assert that these clusters will help scholars of AL to understand the dominant streams in the literature and provide a foundation for future research.
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Boyi Li, Miao Tian, Xiaohan Liu, Jun Li, Yun Su and Jiaming Ni
The purpose of this study is to predict the thermal protective performance (TPP) of flame-retardant fabric more economically using machine learning and analyze the factors…
Abstract
Purpose
The purpose of this study is to predict the thermal protective performance (TPP) of flame-retardant fabric more economically using machine learning and analyze the factors affecting the TPP using model visualization.
Design/methodology/approach
A total of 13 machine learning models were trained by collecting 414 datasets of typical flame-retardant fabric from current literature. The optimal performance model was used for feature importance ranking and correlation variable analysis through model visualization.
Findings
Five models with better performance were screened, all of which showed R2 greater than 0.96 and root mean squared error less than 3.0. Heat map results revealed that the TPP of fabrics differed significantly under different types of thermal exposure. The effect of fabric weight was more apparent in the flame or low thermal radiation environment. The increase in fabric weight, fabric thickness, air gap width and relative humidity of the air gap improved the TPP of the fabric.
Practical implications
The findings suggested that the visual analysis method of machine learning can intuitively understand the change trend and range of second-degree burn time under the influence of multiple variables. The established models can be used to predict the TPP of fabrics, providing a reference for researchers to carry out relevant research.
Originality/value
The findings of this study contribute directional insights for optimizing the structure of thermal protective clothing, and introduce innovative perspectives and methodologies for advancing heat transfer modeling in thermal protective clothing.
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Qingqing ZONG, Yi ZHANG and Yuyu CHEN
This paper theoretically and empirically analyzes the effects of the elderly’s physical health status on their need for care and the choice of care models in China.
Abstract
Purpose
This paper theoretically and empirically analyzes the effects of the elderly’s physical health status on their need for care and the choice of care models in China.
Design/methodology/approach
Empirically, the estimation results of a large-sample randomized intervention trial with chronic obstructive pulmonary disease (COPD) patients through the difference-in-difference method indicated the following: (1) After the COPD intervention trial, the physical health status of the elderly in the treatment group improved significantly, the need for care was substantially reduced and the health improvement led to a 35.5% reduction in the probability of using elderly care. (2) The reduction in the need for care regarding the treatment group occurred mainly in social care. The probability of using social care decreased by 67.8% due to the elderly’s health improvement, while that of home care remained unchanged generally. (3) Further heterogeneity tests suggested that families with fewer potential internal resources for caregiving had a more pronounced decline in the need for social care.
Findings
Theoretically, these empirical results support the existence of the “pecking order” theory in the family’s choice of elderly care model, that is, families tend to employ all internal resources for caregiving before resorting to social care, resulting in a higher sensitivity of social care to health.
Originality/value
The main policy implication of this paper is that ex ante preventive health intervention policies can significantly alleviate the burden of care, especially social care, on families. And preventive health intervention policies are particularly effective in reducing the burden of the families with relatively few resources for informal internal care.
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Niharika Mehta, Seema Gupta and Shipra Maitra
Foreign direct investment in the real estate (FDIRE) sector is required to bridge the gap between investment needed and domestic funds. Further, foreign direct investment is…
Abstract
Purpose
Foreign direct investment in the real estate (FDIRE) sector is required to bridge the gap between investment needed and domestic funds. Further, foreign direct investment is gaining importance because other sources of raising finance such as External Commercial Borrowing and foreign currency convertible bonds have been banned in the Indian real estate sector. Therefore, the objective of the study is to explore the determinants attracting foreign direct investment in real estate and to assess the impact of those variables on foreign direct investments in real estate.
Design/methodology/approach
Johansen cointegration test, vector error correction model along with variance decomposition and impulse response function are employed to understand the nexus of the relationship between various macroeconomic variables and foreign direct investment in real estate.
Findings
The results indicate that infrastructure, GDP and tourism act as drivers of foreign direct investment in real estate. However, interest rates act as a barrier.
Originality/value
This article aimed at exploring factors attracting FDIRE along with estimating the impact of identified variables on FDI in real estate. Unlike other studies, this study considers FDI in real estate instead of foreign real estate investments.
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Shuai Yue, Ben Niu, Huanqing Wang, Liang Zhang and Adil M. Ahmad
This paper aims to study the issues of adaptive fuzzy control for a category of switched under-actuated systems with input nonlinearities and external disturbances.
Abstract
Purpose
This paper aims to study the issues of adaptive fuzzy control for a category of switched under-actuated systems with input nonlinearities and external disturbances.
Design/methodology/approach
A control scheme based on sliding mode surface with a hierarchical structure is introduced to enhance the responsiveness and robustness of the studied systems. An equivalent control and switching control rules are co-designed in a hierarchical sliding mode control (HSMC) framework to ensure that the system state reaches a given sliding surface and remains sliding on the surface, finally stabilizing at the equilibrium point. Besides, the input nonlinearities consist of non-symmetric saturation and dead-zone, which are estimated by an unknown bounded function and a known affine function.
Findings
Based on fuzzy logic systems and the hierarchical sliding mode control method, an adaptive fuzzy control method for uncertain switched under-actuated systems is put forward.
Originality/value
The “cause and effect” problems often existing in conventional backstepping designs can be prevented. Furthermore, the presented adaptive laws can eliminate the influence of external disturbances and approximation errors. Besides, in contrast to arbitrary switching strategies, the authors consider a switching rule with average dwell time, which resolves control problems that cannot be resolved with arbitrary switching signals and reduces conservatism.
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Zongduo Wu, Zhi Zong and Lei Sun
– The purpose of this paper is to provide an improved Mie-Grüneisen mixture model to simulate underwater explosion (UNDEX).
Abstract
Purpose
The purpose of this paper is to provide an improved Mie-Grüneisen mixture model to simulate underwater explosion (UNDEX).
Design/methodology/approach
By using Mie-Grüneisen equations of state (EOS) to model explosive charge, liquid water and solid structure, the whole fluid field is considered as a multi-phases mixture under Mie-Grüneisen EOS. Then by introducing auxiliary variables in Eulerian model and using mass fraction to establish a diffusion balance, a new improved Mie-Grüneisen mixture model is presented here. For the new reconstructed mixture model, a second order MUSCL scheme with TVD limiter is employed to solve the multi-phase Riemann problem.
Findings
Numerical examples show that the results obtained by Mie-Grüneisen mixture model are quite closed to theoretical and empirical data. The model can be also used in 2-D fluid-structure problem of UNDEX effectively and it is proved that the deformation of structure can be clearly described by mass fraction.
Research limitations/implications
The FVM model based on mass fraction can only describe the motion of compressible material under impact. Material failure or large deformation needs a modification about the EOS or implementations of other models (i.e. FEM model).
Originality/value
An improved non-oscillation Mie-Grüneisen mixture model, which based on mass fraction, is given in the present paper. The present Mie-Grüneisen mixture model provides a simplified and efficient way to simulate UNDEX. The feasibility of this model to simulate the detonation impacts on different mediums, including water and other metal mediums, is tested and verified here. Then the model is applied to the simulation of underwater contact explosion problem. In the simulation, deformation of structure under explosion loads, as well as second shock wave, are studied here.
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This study aims to highlight that security and flexibilities remain the main points of contention in the cordiality business. This research points to planning a framework that…
Abstract
Purpose
This study aims to highlight that security and flexibilities remain the main points of contention in the cordiality business. This research points to planning a framework that empowers hotel users to get to the room using a mobile access key. Advancing secured facilities, mobile phone “Near Field Communication” (NFC) innovation as the entrance device by carrying out an application containing an imitated mobile key for explicit verification access is used.
Design/methodology/approach
The proposed system is evaluated by triangulation of experimental, numerical and rational evaluation using partial least square structural equation modeling (PLS-SEM) with Malaysian hotel guests and employees.
Findings
The discoveries with the hypothesis supported validated that the suggested solution can eliminate physical cards, boost protection and encourage a contactless ecosystem. Theoretical, management and societal contributions are discussed here.
Research limitations/implications
This experiment comes with the constraints that it was conducted in only two hotels and does not fully reflect the choices of a wider range of travellers. Secondly, the cost of existing NFC smart locks is still relatively high, and along with the development of technology, the price will decrease when supply exceeds demand.
Practical implications
To promote high-security attributes, NFC technology as the access system by implementing an application containing an emulated smart key for specific authentication access is used. The host-card emulation enables cost-effectiveness profit and initiating a defence system in the pandemic era.
Social implications
To promote high-security attributes, NFC technology is used as the access system by implementing an application containing an emulated smart key for specific authentication access. The host-card emulation enables cost-effectiveness profit and initiating a defence system in the pandemic era.
Originality/value
The novelty of this study comes from the use of commonly available smartphone NFC features that are yet to be applied in the tourism ecosystem. The research provokes the applied concept of mobile smartkeys.