Yu Xia, Shulong Yan and Mengying Jiang
The rapid emergency remote teaching has moved informal learning programs online including makerspaces, which has created an opportunity for harnessing the benefits of virtual…
Abstract
Purpose
The rapid emergency remote teaching has moved informal learning programs online including makerspaces, which has created an opportunity for harnessing the benefits of virtual makerspaces. This study reports on findings from three club designers and facilitators’ reflections on a fully virtual maker club offered in the summer of 2023. This paper aims to inform practitioners of the potential challenges and strategies to resolve various issues.
Design/methodology/approach
Reflective video journaling was conducted by facilitators. Videos were transcribed and analyzed for observations, learning events, challenges and strategies.
Findings
Findings present strategies adopted to address problems during implementation and a checklist for practitioners. The problems are associated with the learning environments, technology tools and student participation. The authors adopted in-the-moment and short-term strategies to tackle the problems and long-term strategies that bear implications for future virtual makerspaces.
Practical implications
This paper can provide direct guidance to practitioners in schools, libraries, museums, etc., who plan to offer informal collaborative learning for children online. It prepares practitioners for the potential challenges and equip them with concrete strategies and questions.
Social implications
Fully virtual makerspaces have the potential to reach a wider range of audience.
Originality/value
To the best of the authors’ knowledge, this paper is the first to report the reflective findings on a fully virtual makerspace club that comprehensively covers challenges and strategies before, during and after the club, which has direct implications for future offerings of such programs.
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Yan Xia, Yi Wan, Hongwei Wang and Zhanqiang Liu
As the transmission component of a locomotive, the traction gear pair system has a direct effect on the stability and reliability of the whole machine. This paper aims to provide…
Abstract
Purpose
As the transmission component of a locomotive, the traction gear pair system has a direct effect on the stability and reliability of the whole machine. This paper aims to provide a detailed dynamic analysis for the traction system under internal and external excitations by numerical simulation.
Design/methodology/approach
A non-linear dynamic model of locomotive traction gear pair system is proposed, where the comprehensive time-varying meshing stiffness is obtained through the Ishikawa formula method and verified by the energy method, and then the sliding friction excitation is analyzed based on the location of the contact line. Meantime, the adhesion torque is constructed as a function of the adhesion-slip feature between wheelset and rail. Through Runge–Kutta numerical method, the system responses are studied with varying bifurcation parameters consisting of exciting frequency, load fluctuation, gear backlash, error fluctuation and friction coefficient. The dynamic behaviors of the system are analyzed and discussed from bifurcation diagram, time history, spectrum plot, phase portrait, Poincaré map and three-dimensional frequency spectrum.
Findings
The analysis results reveal that as control parameters vary the system experiences complex transition among a diverse range of motion states such as one-periodic, multi-periodic and chaotic motions. Specifically, the significant difference in system bifurcation characteristics can be observed under different adhesion conditions. The suitable gear backlash and error fluctuation can avoid the chaotic motion, and thus, reduce the vibration amplitude of the system. Similarly, the increasing friction coefficient can also suppress the unstable state and improve the stability of the system.
Originality/value
The numerical results may provide a systemic understanding of dynamic characteristics and present some available information to design and optimize the transmission performance of the locomotive traction system.
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Qingyan Jiang, Cuihong Yang, Jie Wu and Yan Xia
Known as the major capital providers in Belt and Road countries and the largest carbon emitter in the world, what role China's outward direct investment (ODI) plays in carbon…
Abstract
Purpose
Known as the major capital providers in Belt and Road countries and the largest carbon emitter in the world, what role China's outward direct investment (ODI) plays in carbon neutralization has become a matter of concern. This study aims to measure the impact of China's ODI on the carbon emissions of Belt and Road countries.
Design/methodology/approach
Based on an econometric model and an inter-regional input–output model, a new model measuring the carbon emission effects of ODI is developed.
Findings
The empirical results show that (1) in general, China's ODI generates an emission-reduction effect in Belt and Road countries; (2) The relationship between the emission-reduction effect and income level of host countries shows an approximate inverted U-shaped trend; and (3) China's ODI generates stronger emission-reduction effects on capital-intensive industries.
Originality/value
This study quantitatively measures the scale of carbon emission-increase and reduction effect, which is relatively lacking in previous studies. This study explores the heterogeneity from the perspectives of regions, countries and industries. The authors have compiled an inter-regional input–output table for the Belt and Road countries for 2014 to provide a broad basis for the study of related issues.
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Wenyi Xia, Kun Wang and Anming Zhang
This chapter reviews three main issues in the interactions between air transport and high-speed rail (HSR) in China, namely the interaction between low-cost carriers (LCCs) and…
Abstract
This chapter reviews three main issues in the interactions between air transport and high-speed rail (HSR) in China, namely the interaction between low-cost carriers (LCCs) and HSR, HSR speed effect on airlines, and airline–HSR integration. Studies on these three aspects of airline–HSR interactions have yet been well reviewed, and our chapter aims to fill in this gap. In this chapter, we comprehensively survey literature on the topics, especially studies on Chinese markets that have recently witnessed major HSR developments (and have planned further large-scale HSR expansion in the coming years). Our review shows that, first, compared to full-service carriers, LCCs face fiercer competition from HSR. However, the expansion of HSR network in China can be better coordinated with LCC development. Second, HSR speed exerts two countervailing effects on airline demand and price (the “travel-time” effect and “safety” effect, respectively). Specifically, an HSR speed reduction can have a positive effect on airlines due to longer HSR travel time, but a negative effect on airlines due to improved perception on HSR safety. Third, airline–HSR integration can be implemented through cooperation between airlines and HSR operators and through co-location of airports and HSR stations and can have important implications for intermodal transport and social welfare.
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Xia Yan, Kai Zhang, Mudassir Nawaz and Sanchit Rai
In reservoir history matching the least square objective function is usually used to minimize the mismatch between the predicted production data and the observations. However, as…
Abstract
In reservoir history matching the least square objective function is usually used to minimize the mismatch between the predicted production data and the observations. However, as history matching is an ill-posed inverse problem with non-unique solutions, the reservoir model after calibrating may be far from the real geology model by only matching the production data. In order to solve this problem, a regularization method for reservoir history matching is implemented, in which not only the production data is matched, but prior geological information is also used to correct and update the current reservoir model so that the updated model will be consistent with the geologic model. In this paper, the simultaneous perturbation stochastic approximation method (SPSA) coupled with fast streamline simulation provides an effective method (SLSPSA) to optimize the objective function. As a stochastic approximation algorithm, SLSPSA can guarantee the convergence of the algorithm. Compared to the gradient-based algorithms, it avoids the massive calculation and storage for adjoint or sensitivity matrix. In the calculation process of algorithm, parallel computing is implemented, which reduces the simulation time and improves the computational efficiency. The method was verified by matching an example test.
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Hao‐Bo Zhang, Yan‐qiu Xia, Zhi‐lu Liu and Jun Zhao
The purpose of this paper is to test two kinds of rare earth complexes of Lanthanum Dialkyldithiophosphate (LaDDP) and Lanthanum Dialkylphosphate (LaDP) as lubricant additives in…
Abstract
Purpose
The purpose of this paper is to test two kinds of rare earth complexes of Lanthanum Dialkyldithiophosphate (LaDDP) and Lanthanum Dialkylphosphate (LaDP) as lubricant additives in liquid paraffin for the untreated 60Si2Mn steel and laser‐cladding Ni35A coating on 60Si2Mn steel sliding pairs which are a potential substitute for Zinc Dialkldithiophosphate (ZnDDP).
Design/methodology/approach
Tribological properties were evaluated by an Optimol‐SRV oscillating friction and wear test. The morphologies of the worn surfaces were observed by a scanning electron microscope (SEM), and the chemical states of several typical elements on the worn surfaces were examined by means of X‐ray photoelectron spectroscopy (XPS).
Findings
Treated laser cladding coatings of steel can improve its hardness and strength and the coated steel possess higher load‐carrying capacity than that of 60Si2Mn; The rare earth complexes of LaDDP and LaDP possess good oil‐solubility, friction‐reducing and wear resistance properties. Those rare earth complexes as additives in liquid paraffin during the friction process can form a protective film containing rare earth oxide, sulfate and sulfur‐containing compound during the friction process.
Research limitations/implications
The paper presents two kinds of potentially useful, environmentally‐friendly and highly efficient substitutes for the ZnDDP additives in lubricants.
Practical implications
Owing to their good friction‐reducing and wear resistance properties, LaDDP and LaDP are two optimum and promising industry lubrication additives.
Originality/value
This work is a new application of rare earth complex as lubricant additive in liquid paraffin, which provides a new direction for designing friction pairs and lubricant additive. The tribology experiments have been carried out through the variation of experiment conditions.
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Zhengfeng Jia, Yan-qiu Xia, Xin Shao and San-ming Du
– The purpose of this paper is to investigate the tribological properties of poly-alpha-olefin (PAO) with nano/microstructure core-shell lanthanum borate-SiO2 composites (OCLS).
Abstract
Purpose
The purpose of this paper is to investigate the tribological properties of poly-alpha-olefin (PAO) with nano/microstructure core-shell lanthanum borate-SiO2 composites (OCLS).
Design/methodology/approach
Oleic acid-capped core-shell lanthanum borate-SiO2 composites were synthesized by an easy way. The composites were characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The friction and wear behaviors of the quenched AISI 1045 steel specimens sliding against AISI 52100 steel under the lubrication of PAO containing OCLS were comparatively investigated with PAO containing SiO2 additive on an Optimol SRV reciprocating friction and wear tester. On the other hand, the tribological properties of the PAO containing OCLS were also investigated on four-ball tester.
Findings
The diameter of OCLS was about 20 nm, and the thickness of the SiO2 shell was less than 5 nm. The ratio of oleic acid (OA) is about 15 percent. The PAO containing OCLS possesses much better tribological properties than that of pure PAO and PAO containing SiO2 additive.
Originality/value
The PAO+OCLS possess a better friction reducing and antiwear properties than pure PAO. The new additive can improve the tribological ability of machinery.
Daniil Ilyich Golubtsov, Damian Kedziora, Rysty Bozmanaevna Sartova and Paweł Kędziora
The main objective of the study was to identify main trends, research directions and important authors in the field of supply chain management (SCM) and logistics in the context…
Abstract
The main objective of the study was to identify main trends, research directions and important authors in the field of supply chain management (SCM) and logistics in the context of digital transformation and automation through the application of bibliometric analysis. The study is based on the analysis of academic publications and research studies covering the topics of digital transformation (incl. automation) of the logistics sector and SCM. For this purpose, bibliometric methods are applied, including keyword frequency analysis, identification of the most cited sources and authors. The chapter identifies main trends and research directions in the field of digital transformation of the logistics sector and SCM. Also, the most influential sources and authors making significant contributions to the development of this field are identified. Top 10 best authors, citations and documents got illustrated. The results of the study can be useful for researchers involved in the digital transformation of the logistics sector and SCM, as well as for practitioners developing strategies and solutions in the field of logistics and SCM. The bibliometric analysis provides valuable information on status and trends in research on digital transformation of the logistics sector and SCM (444 documents analyzed), which can be useful for further research and strategy development in this area. Based on the results of the study, it was possible to identify that the increase in research on digital transformation of the logistics sector and SCM is related to the emergence and subsequent epidemic of the COVID-19 virus.
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Yuan Li, Yanzhi Xia, Min Li, Jinchi Liu, Miao Yu and Yutian Li
In this paper the aim is that Aramid/alginate blended nonwoven fabrics were prepared, and the flame retardancy of the blended nonwoven fabrics was studied by thermogravimetric…
Abstract
Purpose
In this paper the aim is that Aramid/alginate blended nonwoven fabrics were prepared, and the flame retardancy of the blended nonwoven fabrics was studied by thermogravimetric analysis, vertical flame test, limiting oxygen index (LOI) and cone calorimeter test.
Design/methodology/approach
The advantages of different fibers can be combined by blending, and the defects may be remedied. The study investigates whether incorporating alginate fibers into aramid fibers can enhance the flame retardancy and reduce the smoke production of prepared aramid/alginate blended nonwoven fabrics.
Findings
Thermogravimetric analysis indicated that alginate fibers could effectively inhibit the combustion performance of aramid fibers at a higher temperature zone, leaving more residual chars for heat isolation. And vertical flame test, LOI and cone calorimeter test testified that the incorporation of alginate fibers improved the flame retardancy and fire behaviors. When the ratio of alginate fibers for aramid/alginate blended nonwoven fabrics reached 80%, the incorporation of alginate fibers could notably decreased peak-heat release rate (54%), total heat release (THR) (29%), peak-smoke production rate (93%) and total smoke production (86%). What is more, the lower smoke production rate and lower THR of the blends vastly reduced the risk of secondary injury in fires.
Originality/value
This study proposes to inhibit the flue gas release of aramid fiber and enhance the flame retardant by mixing with alginate fiber, and proposes that alginate fiber can be used as a biological smoke inhibitor, as well as a flame retardant for aramid fiber.