Yan Jun Xi, Yong Jun Liu, Zhi Xin Wang and Jin Bin Liu
The purpose of this paper is to investigate the oxidation behavior of Ti‐48Al‐8Cr‐2Ag (at.%) at 900°C and 1000°C for various different times.
Abstract
Purpose
The purpose of this paper is to investigate the oxidation behavior of Ti‐48Al‐8Cr‐2Ag (at.%) at 900°C and 1000°C for various different times.
Design/methodology/approach
Laboratory tests were performed to determine growth process of the oxide scale at 900°C and 1000°C for various different times with SEM/EDX, XRD and TEM.
Findings
Merely Al2O3 occurred on the Laves phase at the initial stage at 900°C, while a mixture of Al2O3+TiO2 formed at the initial stage at 1000°C. Oxidation rate of the alloy at 900°C after long‐term oxidation was higher than that at 1000°C because a dense Al2O3 scale formed on the surface at 1000°C.
Originality/value
The paper shows that the oxidation behavior of TiAl alloy at initial stage is the basis of the revealing mechanism of oxidation. It is necessary to further investigate the oxidation of Ti‐Al‐Cr‐Ag alloy in more detail to clearly understand its oxidation process and growth process of the oxide scale.
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Yan Jun Xi, Yong Jun Liu, Zhi Xin Wang and Jin Bin Liu
The purpose of this paper is to investigate the high‐temperature oxidation behavior in air at 900‐1,000°C and electrochemical corrosion performance in 3.5 percent NaCl solution of…
Abstract
Purpose
The purpose of this paper is to investigate the high‐temperature oxidation behavior in air at 900‐1,000°C and electrochemical corrosion performance in 3.5 percent NaCl solution of Ti‐24Al‐17Nb‐0.5Mo (at. %) alloy with Ti‐48Al‐8Cr‐2Ag (at. %) coating.
Design/methodology/approach
Laboratory tests are performed to determine the effect of the Ti‐48Al‐8Cr‐2Ag (at. %) coating on the corrosion performance of Ti3Al alloy.
Findings
It is found that the oxidation rate of sputtered Ti‐48Al‐8Cr‐2Ag nanocrystalline coating is lower than that of the Ti3Al alloy at 900°C. The former forms a scale of merely Al2O3 and the latter forms a scale of TiO2. However, the Ti‐48Al‐8Cr‐2Ag nanocrystalline coating shows a slightly higher oxidation rate than did the Ti3Al alloy at 1,000°C, because outer TiO2 scale forms and columnar boundaries of the coating give a larger actual oxidation area than the original alloy. The coating shows the excellent electrochemical corrosion resistance in 3.5 percent NaCl solution because it exhibits stable passive polarization behavior without any overpassivation phenomena.
Originality/value
TiAlCrAg coatings may become a promising protective coating for Ti3Al‐base intermetallics, which improve the Al2O3 scale formation and make the passivation stable.
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Zhiwei Kang, Xin He, Jin Liu and Tianyuan Tao
The authors proposed a new method of fast time delay measurement for integrated pulsar pulse profiles in X-ray pulsar-based navigation (XNAV). As a basic observation of exact…
Abstract
Purpose
The authors proposed a new method of fast time delay measurement for integrated pulsar pulse profiles in X-ray pulsar-based navigation (XNAV). As a basic observation of exact orientation in XNAV, time of arrival (TOA) can be obtained by time delay measurement of integrated pulsar pulse profiles. Therefore, the main purpose of the paper is to establish a method with fast time delay measurement on the condition of limited spacecraft’s computing resources.
Design/methodology/approach
Given that the third-order cumulants can suppress the Gaussian noise and reduce calculation to achieve precise and fast positioning in XNAV, the proposed method sets the third-order auto-cumulants of standard pulse profile, the third-order cross-cumulants of the standard and the observed pulse profile as basic variables and uses the cross-correlation function of these two variables to estimate the time delay of integrated pulsar pulse profiles.
Findings
The proposed method is simple, fast and has high accuracy in time delay measurement for integrated pulsar pulse profiles. The result shows that compared to the bispectrum algorithm, the method improves the precision of the time delay measurement and reduced the computation time significantly as well.
Practical implications
To improve the performance of time delay estimation in XNAV systems, the authors proposed a novel method for XNAV to achieve precise and fast positioning.
Originality/value
Compared to the bispectrum algorithm, the proposed method can improve the speed and precision of the TOA’s calculation effectively by using the cross-correlation function of integrated pulsar pulse profile’s third-order cumulants instead of Fourier transform in bispectrum algorithm.
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Bin Zhou, Jin Ma, Hongyan Zhou, Xiaoliang Shi and Ahmed Mohamed Mahmoud Ibrahim
This paper aims to investigate the friction noise properties of M50 matrix curved microporous channel composites filled with solid lubricant Sn-Ag-Cu (MS).
Abstract
Purpose
This paper aims to investigate the friction noise properties of M50 matrix curved microporous channel composites filled with solid lubricant Sn-Ag-Cu (MS).
Design/methodology/approach
Pure M50 (MA) and MS are prepared by selective laser melting and vacuum-pressure infiltration technology. The tribological and friction noise properties of MA and MS are tested through dry sliding friction and then the influential mechanism of surface wear sate on friction noise is investigated by analyzing the variation law of noise signals and the worn surface characteristics of MS.
Findings
Experimental results show that the friction noise sound pressure level of MS is only 75.6 dB, and it mainly consists of low-frequency noise. The Sn-Ag-Cu improves the surface wear state, which reduces self-excited vibration of the interface caused by fluctuation of friction force, leading to the decrease of friction noise.
Originality/value
This investigation is meaningful to improve the tribological property and suppress the friction noise of M50 bearing steel.
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Qiongqiong Gu, Rong Zhang and Bin Liu
Due to product value uncertainty, consumers do not know the product matching rate before they get the product, which is the probability of product fitness. Taking the consumers’…
Abstract
Purpose
Due to product value uncertainty, consumers do not know the product matching rate before they get the product, which is the probability of product fitness. Taking the consumers’ anticipated regret into account, this paper aims to develop a theoretical model to explore how the anticipated regret affects pricing and advertising decisions and profits of retailers in the online to offline (O2O) supply chain.
Design/methodology/approach
This paper considers an O2O supply chain consisting of an e-retailer and a brick-and-mortar retailer; both retailers cooperate to provide buying online and pick up in-store (BOPS) for consumers.
Findings
It shows three major findings. Retailers should decide whether to introduce BOPS channel according to the matching rate of the product when the BOPS channel is not very convenient for consumers. When the BOPS channel does not exist in the market, the profits of two retailers increase with the online regret of consumers, while the BOPS channel exists in the market and the matching rate of the product is low, the higher offline regret can enable both retailers to increase the profits; furthermore, when the matching rate is high, the higher degree of online regret can bring more profit to the O2O supply chain. Therefore, both retailers can take measures together to induce consumers’ regrets according to the different matching rates, which makes both retailers obtain more profits. Counterintuitively, consumer surplus will not always increase due to consideration of anticipated regret.
Research limitations/implications
The model has some limitations that are worth further discussing. First, in practice, the O2O supply chain includes many forms except the BOPS channel, for example, order online and pick-up in-store (ROPS) channel; future research can discuss and consider the impact of consumers’ anticipated regret on ROPS. Second, the authors consider that O2O is a supply chain composed of two retailers. In reality, there is also a situation where an oligopoly retailer opens two channels to realize O2O supply chain, in the case the inventory decision-making of the product is worth studying. Finally, to highlight the impact of the anticipated regret on consumers’ decision-making, the return of the product is not considered. Future research can take the return of the product into account to assess the robustness of the results.
Originality/value
The contributions are in two main aspects. First, this paper considers an O2O supply chain with consumer value uncertainty, where there are duopoly retailers in the market and most of the existing literature focus on oligopoly retailer operates both online and offline channels; meanwhile, consumers’ value perceptions of the product is deterministic. Second, this paper explores how the consumer anticipated channel regret affects the pricing and advertising decisions of O2O supply chain, and the authors take behavioral theory into account when studying omnichannel operations, while most studies on anticipated regret consider traditional two-stage price reduction management, product innovation, etc.
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Yuanyuan Liu, Fan Zhang, Bin Li, Pingqing Liu, Shuzhen Liu and Qiong Sun
This study reveals the trigger of innovative behavior from the perspective of intrinsic and extrinsic spiritual inspiration and provides a new research idea for the formation…
Abstract
Purpose
This study reveals the trigger of innovative behavior from the perspective of intrinsic and extrinsic spiritual inspiration and provides a new research idea for the formation mechanism of innovative behavior. The purpose of this study is to provide certain guidance and implications for enterprises to cultivate and enhance employees’ innovative behavior.
Design/methodology/approach
We conducted three studies, collected multi-source data (N = 1,175) from different countries longitudinally, as well as used hierarchical regression analysis and fuzzy-set quantitative comparative analysis to verify the theoretical model.
Findings
According to the findings, both spiritual leadership and career calling have a positive impact on employees’ innovative behavior through the mediating effect of autonomous motivation and the moderating effect of person-vocation fit.
Originality/value
Innovative behavior is the positive professional pursuit of employees, which is difficult to form without the motivation of spiritual factors. Spirituality is a complex concept that contains intrinsic and extrinsic spiritual factors, both of which could stimulate employees’ innovative behavior. Although many discussions have been held on this topic in recent years, little attention has been paid simultaneously to the motivating effects of the two perspectives. Drawn from self-determination theory, this study explores the mechanisms of two spiritual motivation paths (i.e. the intrinsic and extrinsic spiritual motivation paths) in the improvement of employees’ innovative behavior.
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Haoqiang Yang, Xinliang Li, Deshan Meng, Xueqian Wang and Bin Liang
The purpose of this paper is using a model-free reinforcement learning (RL) algorithm to optimize manipulability which can overcome difficulties of dilemmas of matrix inversion…
Abstract
Purpose
The purpose of this paper is using a model-free reinforcement learning (RL) algorithm to optimize manipulability which can overcome difficulties of dilemmas of matrix inversion, complicated formula transformation and expensive calculation time.
Design/methodology/approach
Manipulability optimization is an effective way to solve the singularity problem arising in manipulator control. Some control schemes are proposed to optimize the manipulability during trajectory tracking, but they involve the dilemmas of matrix inversion, complicated formula transformation and expensive calculation time.
Findings
The redundant manipulator trained by RL can adjust its configuration in real-time to optimize the manipulability in an inverse-free manner while tracking the desired trajectory. Computer simulations and physics experiments demonstrate that compared with the existing methods, the average manipulability is increased by 58.9%, and the calculation time is reduced to 17.9%. Therefore, the proposed method effectively optimizes the manipulability, and the calculation time is significantly shortened.
Originality/value
To the best of the authors’ knowledge, this is the first method to optimize manipulability using RL during trajectory tracking. The authors compare their approach to existing singularity avoidance and manipulability maximization techniques, and prove that their method has better optimization effects and less computing time.
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Bin Nie, Diqing Liu, Xiaohui Liu and Wenjing Ye
The purpose of this paper is to propose a new non-parametric phase I control chart for the problem of non-linear profile outlier detection.
Abstract
Purpose
The purpose of this paper is to propose a new non-parametric phase I control chart for the problem of non-linear profile outlier detection.
Design/methodology/approach
The proposed non-parametric method is based on a modified Hausdorff distance, which does not require a restrictive assumption on the form of profiles. By obtaining the distance between each profile and the baseline profile, the authors introduced an iterative optimization clustering algorithm to identify outliers by clustering distances.
Findings
The simulation results show that the proposed method can distinguish outliers for structural changes of non-linear profiles. The authors also present a real industrial case example to highlight how practitioners can implement and make use of the proposed control chart in outlier detection applications, and it achieves higher accuracy in the outlier detection of complex profiles.
Practical implications
The research results of this paper can be applied to any manufacturing or service system whose quality characteristics are characterized by non-linear profiles. This new approach provides quality practitioners a better decision-making tool for non-linear profile outlier detection.
Originality/value
Due to the complexity of real-world applications, the non-linear profiles monitoring problem is yet to be addressed. However, the related research still remains rare. And the authors’ proposed non-linear profile control chart, which does not require a restrictive assumption on the form of profiles, shows its applicability and superiority in simulation study and real-world case.
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Abstract
Purpose
This study aimed to explore the spatial accessibility dynamics of urban parks and their driving forces from 1901 to 2010 in terms of the dynamic relationships between spatial morphology and road networks, taking Nanjing City as an example.
Design/methodology/approach
This study mapped and examined the spatiotemporal distribution of urban parks and road networks in four time points at Nanjing: the 1910s, 1930s, 1960s and 2010s, using the analysis methodology of spatial design network analysis, kernel density estimation and buffer analysis. Two approaches of spatial overlaying and data analysis were adopted to investigate the accessibility dynamics. The spatial overlaying compared the parks' layout and the road networks' core, subcore and noncore accessible areas; the data analysis clarified the average data on the city-wide and local scales of the road networks within the park buffer zone.
Findings
The analysis of the changing relationships between urban parks and the spatial morphology of road networks showed that the accessibility of urban parks has generally improved. This was influenced by six main factors: planning implementation, political policies, natural resources, historical heritage and cultural and economic levels.
Social implications
The results provide a reference for achieving spatial equity, improving urban park accessibility and supporting sustainable urban park planning.
Originality/value
An increasing number of studies have explored the spatial accessibility of urban parks through the relationships between their spatial distribution and road networks. However, few studies have investigated the dynamic changes in accessibility over time. Discussing parks' accessibility over relatively long-time scales has practical, innovative and theoretical values; because it can reveal correlational laws and internal influences not apparent in short term and provide reference and implications for parks' spatial equity.