Yazhou Mao, Daqing Li, Lilin Li and Jingyang Zheng
This study aims to improve the tribological properties of hydrodynamic journal bearing via surface texture, as well as the wear and antifriction mechanisms of textured bearing…
Abstract
Purpose
This study aims to improve the tribological properties of hydrodynamic journal bearing via surface texture, as well as the wear and antifriction mechanisms of textured bearing were represented. It provides a design direction for solving the tribological problem of rotor-bearing system.
Design/methodology/approach
In this paper, the variation of surface texture parameters (e.g. texture diameter, d; area density, sp; and depth, hp) were analyzed based on finite difference method. The optimal surface texture parameters were obtained by designing orthogonal experiments, and the relationship between friction and wear properties and microstructure was studied via combining electron probe microanalyzer, scanning electron microscope, X-ray diffractometer and friction and wear testing machine.
Findings
Dimensionless film pressure P increased as the d increased, whereas P first increased and then decreased as the sp and hp increased, and the maximum P was got as sp = 15% and hp = 25 µm, respectively. The friction coefficient of textured surface with suitable parameters was effectively reduced and the textured surface with the best antifriction effect was 5#. Orthogonal experimental design analysis showed that the influence order of factors on friction coefficient was as follows: sp > sp × d > d > d × hp > hp > sp × hp and the friction coefficient first decreased and then increased as the sp, d and hp increased. In addition, the friction and wear mechanism of textured bearing were three body friction and abrasive wear as the matrix structure and hard phase were a single β phase and Mn5Si3, respectively. While the antifriction mechanism of textured surface was able to store abrasive particles and secondary hydrodynamic lubrication was formed.
Originality/value
The sample with reasonable texture parameter design can effectively reduce friction and wear of hydrodynamic journal bearing without reducing the service life, which can provide a reference for improving the lubrication performance and mechanical efficiency of rotor-bearing system.
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Abstract
Purpose
This study aims to answer few questions, such as which factors influence the local government’s choice of private firm investments; what factors influence private firms’ choice of specific local government to make a local investment; and why do some private firms gain a competitive edge by choosing a stakeholder management model of “running the government” in the context of the Chinese transition economy.
Design/methodology/approach
Using a case study approach, this paper provides an in-depth analysis of the Daqing–Geely Case, 2010, and explains why Geely chose Daqing considering the firm perspective and why the Daqing city Government chose Geely considering the local governments’ perspective.
Findings
This study highlights the concept of “co-beneficial” cooperation between government–business by virtue of the institutional innovation of the quasi-property system. In addition, it reveals that the private firms and local governments in the “Daqing–Geely mode” work together for mutual benefits by putting fair negotiation and contract mechanisms in place. Resultantly, private firms secure the commercial interests, and the local governments bring in improved efficiency.
Originality/value
This study consolidates the theory of stakeholders, thereby strengthening the current understanding of “special offer” and “universal offer.”
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Claes Alvstam, Inge Ivarsson and Bent Petersen
The hallmark of today’s global value chains (GVCs), still dominated by multinationals from advanced economies, is a sophisticated international division of labor based on scale…
Abstract
Purpose
The hallmark of today’s global value chains (GVCs), still dominated by multinationals from advanced economies, is a sophisticated international division of labor based on scale economies and prevailing factor endowment differences between countries. However, GVCs led by multinationals from large emerging economies may be configured on the basis of considerations that supplement factor cost efficiencies, namely, those of societal objectives as formulated by political actors in the home country. In this context, the purpose of this paper is to examine the implications of political and socio-economic factors on GVC configuration of multinational firms.
Design/methodology/approach
This paper provides an in-depth case study of a leading Chinese car manufacturer, Zhejiang Geely Holding Group (ZGH) and its value-chain configuration, with a special focus on the acquisition of Volvo Car Corporation.
Findings
The authors show how ZGH’s configuration of its GVC, including that of acquired Volvo Car Corporation, takes place in symbiosis with political actors. The advantages and disadvantages of this symbiosis are highlighted.
Research limitations/implications
The study focuses on GVC configuration of one company, ZGH, in one industry, the automotive industry, in one emerging economy. The external validity of the study may therefore be limited. Furthermore, the focus is on the geographical/locational configuration of GVCs and ignores the ownership aspects.
Originality/value
The paper provides novel empirical evidence to better understand GVC configuration of multinational firms from emerging economies.
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Jun Shi and Ning Liang
Petroleum resource-based city is an important part of urban system in China. Under the background of green growth and economic transition, petroleum resource-based city is facing…
Abstract
Petroleum resource-based city is an important part of urban system in China. Under the background of green growth and economic transition, petroleum resource-based city is facing the problem of sustainable development. This paper takes petroleum resources-based cities in China as the research object, and uses urban ecological planning method to analyze the basic methods of petroleum resources-based urban ecological planning and development from three aspects: establishing multi-level city circle layer, building urban ecotope and promoting urban renewal. The results show that green growth and economic transition of petroleum resources cities in China depend on government planning for urban development, including statutory planning and non-statutory planning. Petroleum resources-based cities should promote the ecological planning and development of petroleum resources-based cities in China from three aspects: optimizing the industrial structure of cities, optimizing the layout of urban functional areas and optimizing the layout of urban ecolandscape in order to adapt to green growth and economic transition.
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Qingchao Cheng, Guangsheng Cao, Congyu Sang, Yujie Bai, Dan Li and Ruixuan Bu
This paper aims to clarify the corrosion inhibition effect of different corrosion inhibitor systems on the corrosion of metal pipe string by potassium persulfate plugging agent…
Abstract
Purpose
This paper aims to clarify the corrosion inhibition effect of different corrosion inhibitor systems on the corrosion of metal pipe string by potassium persulfate plugging agent, so as to improve the injection capacity of polymer plugging well and reduce the corrosion of steel by oxidant plugging agent.
Design/methodology/approach
The effect of different corrosion inhibitors on the corrosion inhibition of N80 carbon steel in 1% potassium persulfate solution was studied by electrochemical experiment and weight loss experiment. The corrosion inhibition mechanism of potassium persulfate inhibitor and the synergistic mechanism among different inhibitors were analyzed.
Findings
The results indicated that when the temperature was 50°C, the inhibition effect of 0.2% sodium molybdate with a single inhibitor was the best at pH 8.5, and the inhibition rate was 70.17%. The inhibition efficiency of 0.2% sodium molybdate + 0.3% sodium silicate in the composite inhibition system can reach 94.38%. In the temperature range of 20°C–60°C, with the increase of system temperature, the inhibition effect of corrosion inhibitor will gradually weaken.
Originality/value
The corrosion inhibition system of N80 steel in potassium persulfate oxidant was mainly studied, and it clarified the influence of temperature and pH value on the corrosion inhibition effect, which provided guidance and suggestions for the corrosion inhibition of tubular string in the oilfield.
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Lei Li, Daqing He, Chengzhi Zhang, Li Geng and Ke Zhang
Academic social (question and answer) Q&A sites are now utilised by millions of scholars and researchers for seeking and sharing discipline-specific information. However, little…
Abstract
Purpose
Academic social (question and answer) Q&A sites are now utilised by millions of scholars and researchers for seeking and sharing discipline-specific information. However, little is known about the factors that can affect their votes on the quality of an answer, nor how the discipline might influence these factors. The paper aims to discuss this issue.
Design/methodology/approach
Using 1,021 answers collected over three disciplines (library and information services, history of art, and astrophysics) in ResearchGate, statistical analysis is performed to identify the characteristics of high-quality academic answers, and comparisons were made across the three disciplines. In particular, two major categories of characteristics of the answer provider and answer content were extracted and examined.
Findings
The results reveal that high-quality answers on academic social Q&A sites tend to possess two characteristics: first, they are provided by scholars with higher academic reputations (e.g. more followers, etc.); and second, they provide objective information (e.g. longer answer with fewer subjective opinions). However, the impact of these factors varies across disciplines, e.g., objectivity is more favourable in physics than in other disciplines.
Originality/value
The study is envisioned to help academic Q&A sites to select and recommend high-quality answers across different disciplines, especially in a cold-start scenario where the answer has not received enough judgements from peers.
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Abstract
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Lei Li, Chengzhi Zhang and Daqing He
With the growth in popularity of academic social networking sites, evaluating the quality of the academic information they contain has become increasingly important. Users'…
Abstract
Purpose
With the growth in popularity of academic social networking sites, evaluating the quality of the academic information they contain has become increasingly important. Users' evaluations of this are based on predefined criteria, with external factors affecting how important these are seen to be. As few studies on these influences exist, this research explores the factors affecting the importance of criteria used for judging high-quality answers on academic social Q&A sites.
Design/methodology/approach
Scholars who had recommended answers on ResearchGate Q&A were asked to complete a questionnaire survey to rate the importance of various criteria for evaluating the quality of these answers. Statistical analysis methods were used to analyze the data from 215 questionnaires to establish the influence of scholars' demographic characteristics, the question types, the discipline and the combination of these factors on the importance of each evaluation criterion.
Findings
Particular disciplines and academic positions had a significant impact on the importance ratings of the criteria of relevance, completeness and credibility. Also, some combinations of factors had a significant impact: for example, older scholars tended to view verifiability as more important to the quality of answers to information-seeking questions than to discussion-seeking questions within the LIS and Art disciplines.
Originality/value
This research can help academic social Q&A platforms recommend high-quality answers based on different influencing factors, in order to meet the needs of scholars more effectively.
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Ji Youjun, K. Vafai, Huijin Xu and Liu Jianjun
This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability…
Abstract
Purpose
This paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability reservoir. The numerical simulation method was used to analyze the process of injected water channeling into the interlayer.
Design/methodology/approach
Some typical cores including the sandstone and the mudstone were selected to test the permeability and the stress sensitivity, and some curves of the permeability varying with the stress for the cores were obtained to demonstrate the sensitivity of the formation. Based on the experimental results and the software Eclipse and Abaqus, the main injection parameters to reduce the amount of the injected water in flowing into the interlayer were simulated.
Findings
The results indicate that the permeability of the mudstone is more sensitive to the stress than sandstone. The injection rate can be as high as possible on the condition that no crack is activated or a new fracture is created in the development. For the B82 block of Daqing oilfield, the suggested pressure of the production pressure should be around 1–3MPa, this pressure must be gradually reached to get a higher efficiency of water injection and avoid damaging the casing.
Originality/value
This work is beneficial to ensure stable production and provide technical support to the production of low permeability reservoirs containing an interlayer.
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Meiling Wang, Qin Li, Zhiqiang Huang, Weiji Qian, Xiong Chen, Qiang Li and Tianhua Lai
This study aims to solve the premature failure of the rubber stator due to wear, reduce the frictional resistance moment of the screw pump to solve the problem of a model of Daqing…
Abstract
Purpose
This study aims to solve the premature failure of the rubber stator due to wear, reduce the frictional resistance moment of the screw pump to solve the problem of a model of Daqing oilfield screw pump oil recovery system shutdown after the difficult start.
Design/methodology/approach
For the first time, the rotor surface of a screw pump was treated with dot-matrix texture to study the effect of dot matrix texture on the tribological performance of the stator-rotor friction subsets of screw pump. Reciprocating friction tests with different texture morphologies (S-shape, double tongue) and angular parameters (0°, 45° and 90°) were conducted at 10% of the texture area and pump silicone grease.
Findings
When point texture was added to the surface of the rotor sample, the friction coefficient and wear quantity of the sample were lower than those of the surface without texture treatment, and the double tongue 0° combination showed the best tribological properties. At this time, the average coefficient of friction and wear is reduced by 22.8% and 62%, 28.6% and 64.8%.
Originality/value
The introduction of texture can effectively improve the tribological performance of progressive screw pumps, and this paper provides important theoretical and experimental support for the design of progressive screw pumps in practical applications.