Cheng Zhang, Liang Wu, Zilong Zhao, Guangsheng Huang, Bin Jiang, A. Atrens and Fusheng Pan
This paper aims to investigate microstructure, corrosion behavior and mechanical properties of Mg-4Li and Mg-4Li-3Al.
Abstract
Purpose
This paper aims to investigate microstructure, corrosion behavior and mechanical properties of Mg-4Li and Mg-4Li-3Al.
Design/methodology/approach
The microstructure was characterized by using scanning electron microscopy and electron backscatter diffraction. The corrosion behaviors were measured by hydrogen evolution and potentiodynamic polarization tests. The mechanical properties were evaluated by tensile tests.
Findings
The addition of Al results in the precipitation of some Mg-Al phase and Al3Li phase particles, and the formation of some fine recrystallized grains.
Originality/value
Mg-4Li-3Al showed a higher corrosion rate than that of Mg-4Li, attributed to the precipitate particles in Mg-4Li-3Al causing microgalvanic corrosion and the change of grain orientation. The addition of 3 Wt. per cent Al increased the tensile strength by solid solution strengthening, precipitation strengthening, refinement strengthening and texture strengthening, whilst the elongation decreased by almost half.
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Wanru Xie, Yixin Zhao, Gang Zhao, Fei Yang, Zilong Wei and Jinzhao Liu
High-speed turnouts are more complex in structure and thus may cause abnormal vibration of high-speed train car body, affecting driving safety and passenger riding experience…
Abstract
Purpose
High-speed turnouts are more complex in structure and thus may cause abnormal vibration of high-speed train car body, affecting driving safety and passenger riding experience. Therefore, it is necessary to analyze the data characteristics of continuous hunting of high-speed trains passing through turnouts and propose a diagnostic method for engineering applications.
Design/methodology/approach
First, Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) is performed to determine the first characteristic component of the car body’s lateral acceleration. Then, the Short-Time Fourier Transform (STFT) is performed to calculate the marginal spectra. Finally, the presence of a continuous hunting problem is determined based on the results of the comparison calculations and diagnostic thresholds. To improve computational efficiency, permutation entropy (PE) is used as a fast indicator to identify turnouts with potential problems.
Findings
Under continuous hunting conditions, the PE is less than 0.90; the ratio of the maximum peak value of the signal component to the original signal peak value exceeded 0.7, and there is an energy band in the STFT time-frequency map, which corresponds to a frequency distribution range of 1–2 Hz.
Originality/value
The research results have revealed the lateral vibration characteristics of the high-speed train’s car body during continuous hunting when passing through turnouts. On this basis, an effective diagnostic method has been proposed. With a focus on practical engineering applications, a rapid screening index for identifying potential issues has been proposed, significantly enhancing the efficiency of diagnostic processes.
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Zilong Wang, Zhiwen Zhang and Ng Choon Yeong Jhony
As a transition economy, China is interested in allocating its limited innovation resources economically, reasonably and efficiently to produce as many outputs as possible with…
Abstract
Purpose
As a transition economy, China is interested in allocating its limited innovation resources economically, reasonably and efficiently to produce as many outputs as possible with its limited financial and human resources. Nonetheless, what is the efficiency of the allocation of innovative resources for civil–military integration enterprises, and what factors hinder its efficiency improvement? The purpose of this paper is to explore these problems.
Design/methodology/approach
The improved two-stage network data envelopment analysis (DEA) method is used to measure the overall efficiency and stage efficiency of the innovation resource allocation of 58 Chinese civil–military integration listed companies from 2010 to 2016. Tobit model is used to analyze the influencing factors of resource allocation efficiency.
Findings
The results indicate that the overall efficiency and stage efficiency of innovation resource allocation fluctuate in varying degrees during the period. The optimization of overall efficiency is restricted by lower efficiency of innovation achievement transformation. Enterprise scale was found to have a significant negative impact on both overall and two-stage efficiencies. Proportion of research and development (R&D) personnel had a positive effect on the overall and two-stage efficiency. Government support had a significant positive effect on the stage of innovation resource development and overall efficiency.
Originality/value
Previous research studies have used either the DEA or stochastic frontier analysis method to measure the efficiency of innovation activities as a whole and ignored the stage of initial investment to final output in innovation activities. That is, the process in which initial input of R&D resources becomes innovation output, and then becomes economic benefits. Therefore, this paper studies the efficiency of innovation resource allocation of civil–military integration listed companies. The improved two-stage chain network DEA method and Tobit model were used.
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Keliang Zhang, Qingfei Min, Zhenhua Liu and Zilong Liu
The purpose of this paper is to explore the factors affecting users’ continuous microblog usage intention. In recent years, the number of microblog users has gradually declined…
Abstract
Purpose
The purpose of this paper is to explore the factors affecting users’ continuous microblog usage intention. In recent years, the number of microblog users has gradually declined. This research can reveal microblog users’ needs and provide the improvement direction of microblog services.
Design/methodology/approach
By integrating Wixom and Todd’s theoretical framework, the Uses and Gratifications Theory and the DeLone and McLean Information System Success Model, a conceptual model is proposed. In this model, gratification is defined as a kind of behavioral attitude, and satisfaction is viewed as an object-based attitude. The survey data were collected online and analyzed using the partial least squares method.
Findings
The results suggest that users’ continuance intention (behavioral intention) is jointly determined by users’ gratification (behavioral-based attitude) and their habitual microblog usage behavior. Likewise, gratification is positively affected by satisfaction (object-based attitude) which is a joint function of system quality and information quality (object-based beliefs).
Originality/value
In this research, Wixom and Todd’s principle is applied as the basic theoretical framework; gratification is viewed as a behavior attitude and user satisfaction is identified as an object-based attitude. This research model is a new lens for continuance usage research.
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Making decisions on preventive maintenance (PM) policy and buffer sizing, as is often studied, may not result in overall optimization. The purpose of this paper is to propose a…
Abstract
Purpose
Making decisions on preventive maintenance (PM) policy and buffer sizing, as is often studied, may not result in overall optimization. The purpose of this paper is to propose a joint model that integrates PM and buffer sizing with consideration of quality loss for a degenerating system, which aims to minimize the average operation cost for a finite horizon. The opportunistic maintenance (OM) policy which could increase the output and decrease the cost of the system is also explored.
Design/methodology/approach
A joint PM and buffer size model considering quality loss is proposed. In this model, the time-based PM and the condition-based PM are taken on the upstream and the downstream machine, respectively. Further, the OM policy based on the theory of constraints (TOC) is also considered. An iterative search algorithm with Monte Carlo is developed to solve the non-linear model. A case study is conducted to illustrate the performance of the proposed PM policies.
Findings
The superiority of the proposed integrated policies compared with the separate PM policy is demonstrated. Effects of the policies are testified. The advantages of the proposed TOC-based OM policy is highlighted in terms of low-cost and high-output.
Originality/value
Few studies have been carried out to integrate decisions on PM and buffer size when taking the quality loss into consideration for degenerating systems. Most PM models treat machines equally ignoring the various roles of them. A more comprehensive and integrated model based on TOC is proposed, accompanied by an iterative search algorithm with Monte Carlo for solving it. An OM policy to further improve the performance of system is also presented.
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Zilong Song and Shiwei He
There are particularly high fresh agricultural product (FAP) loss rates in actual supply chain operation and the development of FAPs e-commerce is hindered to some extent. The…
Abstract
Purpose
There are particularly high fresh agricultural product (FAP) loss rates in actual supply chain operation and the development of FAPs e-commerce is hindered to some extent. The purpose of this paper is to achieve the coordination of three-layer FAP supply chain and maximize profit through the contracts among the supply chain members.
Design/methodology/approach
A three-layer FAP supply chain that consists of a fresh produce e-commerce enterprise, third-party logistics service provider (TPLSP) and community convenience store under e-commerce environment is considered. New game models are developed and optimal decisions in centralized and decentralized channel are characterized. Different contract coordination mechanisms are designed to improve the supply chain performance. Finally, computational studies are conducted.
Findings
The decentralized supply chain cannot be coordinated by a freshness-keeping cost-sharing contract, and it can be coordinated by a freshness-keeping cost-sharing and revenue-sharing contract. The optimal unit online selling price, unit logistics distribution price, fresh-keeping effort and unit self-collection service price can all be achieved.
Practical implications
The paper provides a practical guideline to managers in fresh produce industry in terms of how to cooperate with other supply chain members so as to maximize total profit and achieve Pareto improvement while also supply the freshest and safest produce to the target market under e-commerce environment.
Originality/value
Few studies have explored the coordination of three-layer FAP supply chain under e-commerce environment with TPLSP and community convenience store’s participation in decisions, especially considering that the market demand for FAPs is affected by freshness and unit online selling price. In this paper, all these scenarios are taken into account and corresponding mathematical models are developed. In particular, different contract coordination mechanisms are designed and examined simultaneously.
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Yuan Huang, Zilong Song and Lewis H.K. Tam
The authors examine the joint effect of the country-wide legal institutions and product market competition on stock crash risk in a large sample of international firms.
Abstract
Purpose
The authors examine the joint effect of the country-wide legal institutions and product market competition on stock crash risk in a large sample of international firms.
Design/methodology/approach
In the study, the authors examine whether the country-level institutional factors affect product market competition's impact on stock crash risk. Specifically, the authors characterize country-wide institutional quality with individual governance indices developed in earlier studies and also adopt the worldwide board reforms as a proxy for the change in firms' governance environment.
Findings
The authors find that strong institutions mitigate the positive relationship between product market competition and stock crash risk in the international setting. In addition, the authors find that institutional quality moderates the effect of product market competition on stock crash risk via the information channel, i.e. although firms in competitive industries manage and report earnings more aggressively, strong institutions or board reforms, curtail managers' incentive to do so.
Originality/value
The authors’ findings lend support to the dark side of product market competition with a broader sample from 35 countries. In light of this, when earlier studies consider firms from competitive (concentrated) industries as having less (more) severe agency problems, future studies should consider the agency costs associated with product market competition for both the US firms and non-US firms. Furthermore, when it is debatable that regulators are self-interested, captured, uninformed and thus the regulations and institutions may not be fully effective as a result, this study demonstrates the effectiveness of institutions in ex ante mitigating agency conflicts associated with product market competition.
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This paper aims to address the pressing challenges in research data management within institutional repositories, focusing on the escalating volume, heterogeneity and multi-source…
Abstract
Purpose
This paper aims to address the pressing challenges in research data management within institutional repositories, focusing on the escalating volume, heterogeneity and multi-source nature of research data. The aim is to enhance the data services provided by institutional repositories and modernise their role in the research ecosystem.
Design/methodology/approach
The authors analyse the evolution of data management architectures through literature review, emphasising the advantages of data lakehouses. Using the design science research methodology, the authors develop an end-to-end data lakehouse architecture tailored to the needs of institutional repositories. This design is refined through interviews with data management professionals, institutional repository administrators and researchers.
Findings
The authors present a comprehensive framework for data lakehouse architecture, comprising five fundamental layers: data collection, data storage, data processing, data management and data services. Each layer articulates the implementation steps, delineates the dependencies between them and identifies potential obstacles with corresponding mitigation strategies.
Practical implications
The proposed data lakehouse architecture provides a practical and scalable solution for institutional repositories to manage research data. It offers a range of benefits, including enhanced data management capabilities, expanded data services, improved researcher experience and a modernised institutional repository ecosystem. The paper also identifies and addresses potential implementation obstacles and provides valuable guidance for institutions embarking on the adoption of this architecture. The implementation in a university library showcases how the architecture enhances data sharing among researchers and empowers institutional repository administrators with comprehensive oversight and control of the university’s research data landscape.
Originality/value
This paper enriches the theoretical knowledge and provides a comprehensive research framework and paradigm for scholars in research data management. It details a pioneering application of the data lakehouse architecture in an academic setting, highlighting its practical benefits and adaptability to meet the specific needs of institutional repositories.
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Jun Zheng, Zilong Li, Liang Gao and Guosheng Jiang
The purpose of this paper is to efficiently use as few sample points as possible to get a sufficiently explored design space and an accurate optimum for adaptive metamodel-based…
Abstract
Purpose
The purpose of this paper is to efficiently use as few sample points as possible to get a sufficiently explored design space and an accurate optimum for adaptive metamodel-based design optimization (AMBDO).
Design/methodology/approach
A parameterized lower confidence bounding (PLCB) scheme is proposed in which a cooling strategy is introduced to guarantee the balance between exploitation and exploration by varying weights of the predicting error and optimum of a metamodel. The proposed scheme is investigated by a set of test functions and a structural optimization problem, in which PLCB with four kinds of cooling control functions are studied. Moreover, other infill criteria (such as expected improvement and its extension versions) are taken into comparison.
Findings
Results show that the proposed PLCB (especially PLCB with the first cooling control function) based AMBDO method can find the optimum with fewer evaluations and maintain good accuracy, which means the proposed PLCB contributes to the excellent efficiency and accuracy in finding global optimal solutions.
Originality/value
The parameterized version of the lower confidence bound metric is proposed for AMBDO, typically used in the context of adaptive sampling in efficient global optimization.
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Zilong Wang, JiaCheng Zhou, Fang Liu, Yuqin Wu and Nu Yan
The purpose of this paper is to study the microstructure and properties of Sn-3.5Ag and Sn-3.5Ag-0.5Sb lead-free solder alloys with and without a rotating magnetic field (RMF).
Abstract
Purpose
The purpose of this paper is to study the microstructure and properties of Sn-3.5Ag and Sn-3.5Ag-0.5Sb lead-free solder alloys with and without a rotating magnetic field (RMF).
Design/methodology/approach
Optical microscopy, scanning electron microscopy and X-ray diffraction were used to analyze the effect of an RMF on the microstructure of the solders. Differential scanning calorimetry was used to study the influence of the RMF on the thermal characteristics of the solders. The mechanical properties of the alloys were determined by tensile measurements at different strain rates.
Findings
The ß-Sn grains and intermetallic compounds for the Sn-3.5Ag and Sn-3.5Ag-0.5Sb lead-free solder alloys were refined under an RMF, and the morphology of the ß-Sn grains changed from dendritic to equiaxed. The pasty range was significantly reduced under an RMF. The ultimate tensile strength (UTS) of Sn-3.5Ag improved under the RMF, whereas the UTS of Sn-3.5Ag-0.5Sb decreased slightly. The addition of Sb to the Sn-3.5Ag alloy significantly enhanced the UTS and elongation (El.%) of the samples. The UTS of the solder increased with increasing strain rate.
Originality/value
The results revealed that the application of RMF in the molten alloy had a significant effect on its microstructure and mechanical properties. The thermal characteristics of the Sn-3.5Ag and Sn-3.5Ag-0.5Sb solder alloys were improved under the RMF. This research is expected to fill a knowledge gap regarding the behaviour of Sn-Ag solder alloys under RMF.