Zhen Li, Xiaoli Zhao, Dezhi Zheng, Tingjian Wang, Le Gu and Liqin Wang
This study aims to evaluate the rheological properties of aviation lubricating oil under conditions of heavy load, high speed and high temperature and the applicability of the…
Abstract
Purpose
This study aims to evaluate the rheological properties of aviation lubricating oil under conditions of heavy load, high speed and high temperature and the applicability of the classical rheological model under severe conditions.
Design/methodology/approach
A Chinese aviation lubricating oil was used and its traction curves were obtained using a new two-disk tribotester. Its rheological parameters were calculated based on empirical formulae. Moreover, the traction force was calculated based on the classical Eyring rheological model.
Findings
The traction curves are obtained with respect to contact pressure, temperature and rolling speed. The rheological parameters are significantly influenced by environmental factors, especially viscosity. The traction force calculated using the Eyring model is consistent with the experimental results.
Originality/value
A novel two-disk tribotester was designed using a gas bearing and speed–force closed-loop control to ensure measurement accuracy. The mechanism of rheological properties was analyzed and the applicability of the classical rheological model under severe conditions was verified. It provided an experimental and theoretical basis for expanding the application of classical rheological models under extreme conditions.
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Zhen Li, Yufan Lu, Chi Zhang, Jinlong Dong, Xiaoli Zhao and Liqin Wang
The traction behaviours of lubricating oil significantly affect the stability and lubrication regime of aviation high-speed ball bearings. Rolling elements will slide at a low…
Abstract
Purpose
The traction behaviours of lubricating oil significantly affect the stability and lubrication regime of aviation high-speed ball bearings. Rolling elements will slide at a low traction force (TF). Therefore, traction behaviours need to be studied, and a fitting expression for traction curves to rapidly calculate the traction coefficient (TC) should be developed.
Design/methodology/approach
The traction behaviours of an aviation lubricating oil were studied in severe operating conditions with a self-designed two-disc testing rig. Based on the least squares method and the Levenberg–Marquardt theory, a rapid calculation expression was developed by fitting the obtained traction curves. The correction of this expression was experimentally verified by comparing the TCs under different operating conditions. This expression was also used to modify the commonly accepted quasi-dynamic model of rolling bearings.
Findings
An increase of the load led to an increase in the TC. In comparison, the temperature and entrainment speed showed inverse effects. The proposed expression exactly predicted the trend of the experimentally acquired traction curve. The calculation with the modified dynamic model showed that the action of the TF on a single rolling element varied and that the temperature increase of the outer raceway is higher than the inner raceway, which is caused by the TF and relative sliding speed between the elements and raceways.
Originality/value
The proposed fitting expression is able to simplify the TC calculation of synthetic aviation lubricating oil in practical engineering applications. This paper can provide an important reference for the traction behaviour of synthetic aviation lubricating oil under severe conditions and assist with its rapid calculation and practical application in engineering.
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Yi Zhang and Hao Dong Gu
Scholars have examined the relationship between sports and urban development and proposed to use sport programs and events as a catalyst to revitalize communities, upgrade urban…
Abstract
Purpose
Scholars have examined the relationship between sports and urban development and proposed to use sport programs and events as a catalyst to revitalize communities, upgrade urban infrastructure, promote city image, shift economic structure, nurture an active lifestyle, and enhance societal harmony and solidarity. Yet, previous studies were usually focused on mega sport events and were typically conceptual, theoretical and lack of practical applications. This study was designed to attain in-depth understanding on how a specific sport, table tennis, can be systematically organized and utilized to influence urban development through a qualitative research injury.
Design/methodology/approach
This investigation was carried by conducting in-depth interviews of the executive director of the Shanghai Table Tennis Association, on-site observations and comprehensive review of literature. Development of interview questions took into consideration the conceptual framework postulated by Preuss (2007) that contains six structures of urban development through sports. Triangulation analyses were conducted to cross validate the three information sources to generate themes and assertions.
Findings
While the identified practices were consistent with Preuss' (2007) framework, specific management activities earnestly practiced in Shanghai are centered on utilizing cultural and historical heritage, star power, branding strategies, staging tournaments, hallmark events, technical innovation and government relations to achieve the objectives of table tennis as a sport and the objectives of urban development through table tennis.
Originality/value
The findings of this study help fill the void that a theory usually cannot specify, namely, detailed, unambiguous practices. While table tennis may be a viewed as a small sport in many parts of the world, it has a strong, unprecedented historical heritage in Shanghai. This city has made a prudent choice and investment in this sport, which has proved to be effective. Other cities in the world should look into their own social, cultural and historical heritage and develop sport strategies, operations and programs accordingly.
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Liqin Zhou, Changbin Wang, Lin Li, Chengxi Zhang, Dalei Song and Chong Li
A novel fault-tolerant control (FTC) method is proposed to assure the stability of the remote-operated vehicle (ROV) by considering the thruster failure-induced model…
Abstract
Purpose
A novel fault-tolerant control (FTC) method is proposed to assure the stability of the remote-operated vehicle (ROV) by considering the thruster failure-induced model perturbations. The stability of the ROV with failures is guaranteed and optimized with the determined model perturbation set. The effectiveness of the double-boundary interval fault-tolerant control (DBIFTC) is verified through the experiments and proves that the stability is well maintained, which demonstrates a decent performance.
Design/methodology/approach
This paper studies a control problem for a multi-vector propulsion ROV by using the DBIFTC method in the presence of thruster failure and external disturbances. The ROV kinematics and dynamical models with multi-vector-arranged thruster failure are investigated and formulated for control system design.
Findings
In this paper, the authors address the FTC problem of ROV with multi-vector thrusters and propose a DBIFTC scheme. The advantage is that as the kinematic system model of ROV is preanalyzed and identified, the DBIFTC becomes more effective. The mathematical stability of the system under the proposed control scheme can be guaranteed.
Research limitations/implications
The ROV model used in this paper is based on the system identification of experimental data. Although this model has real experimental value and physical significance, the accuracy can be further improved.
Practical implications
Cable-controlled underwater ROVs are widely used in military missions and scientific research because of their flexibility, sufficient load capacity and real-time information transmission characteristics. The DBIFTC method proposed in this paper can effectively reduce the problem of underwater vehicle under propeller failure or external disturbance and save unnecessary cost.
Social implications
The DBIFTC method proposed in this paper can ensure the attitude stability of ROV or other underwater equipment operating in the event of propeller failure or external disturbance. In this way, the robot can better perform undersea work and tasks.
Originality/value
The kinematics and failure mechanisms of the ROV with multi-vector propulsion system are investigated and established. An optimized DBIFTC scheme is investigated to stabilize ROV yaw attitude under the thruster failure condition. The feasibility and effectiveness of the DBIFTC is experimentally validated.
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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…
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.
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Abstract
Purpose
The purpose of this paper is to theoretically and empirically analyze the impact of the types of micro-innovation on innovation performance and the choice of micro-innovation strategies in different contexts on the basis of an examination of the basis and standards of micro-innovation categorization.
Design/methodology/approach
The authors collected and analyzed 206 survey samples from the Zhejiang Province in China; there were 68, 63 and 75 enterprises at inception, high growth and maturity stages, respectively, and there were, in total, 53, 90 and 63 low-tech manufacturing small and medium enterprises (SMEs), technology-intensive manufacturing SMEs and service-oriented SMEs, respectively. Multiple regression analysis was used to test the hypotheses.
Findings
The analysis results suggest that SMEs at the embryonic stage should choose strategies of imitative innovation, whereas SMEs at growth stage should use continued micro-innovation and independent micro-innovation as the optimal choices; it is better for the SMEs at the mature stage to resort to independent micro-innovation. Low-tech manufacturing SMEs should opt for the continued micro-innovation strategy, and technology-intensive manufacturing SMEs should adopt independent micro-innovation, whereas service-oriented SMEs should choose both continued and independent micro-innovation strategies.
Originality/value
This study sets up a classification framework of micro-innovation and addresses its category and sources, thus extending the micro-innovation research results. The conclusion also supports and enriches the view of open innovation in the innovation theory. Hidden behind the phenomenon that internal and external factors play vital roles, it is a basic rule that innovation activities must be subject to various related factors.
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Lu An, Chuanming Yu, Xia Lin, Tingyao Du, Liqin Zhou and Gang Li
The purpose of this paper is to identify salient topic categories and outline their evolution patterns and temporal trends in microblogs on a public health emergency across…
Abstract
Purpose
The purpose of this paper is to identify salient topic categories and outline their evolution patterns and temporal trends in microblogs on a public health emergency across different stages. Comparisons were also examined to reveal the similarities and differences between those patterns and trends on microblog platforms of different languages and from different nations.
Design/methodology/approach
A total of 459,266 microblog entries about the Ebola outbreak in West Africa in 2014 on Twitter and Weibo were collected for nine months after the inception of the outbreak. Topics were detected by the latent Dirichlet allocation model and classified into several categories. The daily tweets were analyzed with the self-organizing map technique and labeled with the most salient topics. The investigated time span was divided into three stages, and the most salient topic categories were identified for each stage.
Findings
In total, 14 salient topic categories were identified in microblogs about the Ebola outbreak and were summarized as increasing, decreasing, fluctuating or ephemeral types. The topical evolution patterns of microblogs and temporal trends for topic categories vary on different microblog platforms. Twitter users were keen on the dynamics of the Ebola outbreak, such as status description, secondary events and so forth, while Weibo users focused on background knowledge of Ebola and precautions.
Originality/value
This study revealed evolution patterns and temporal trends of microblog topics on a public health emergency. The findings can help administrators of public health emergencies and microblog communities work together to better satisfy information needs and physical demands by the public when public health emergencies are in progress.
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Thi Kieu Van Tran, Ehsan Elahi, Liqin Zhang, Van Huyen Bui, Quang Trung Pham, Thuy Duong Tran, Thi Lien Ta and Munawar Hassan
The purpose of this paper is to investigate the determinants of the gender gap in the gross value of rice yield in Vietnam.
Abstract
Purpose
The purpose of this paper is to investigate the determinants of the gender gap in the gross value of rice yield in Vietnam.
Design/methodology/approach
A panel data set of 12 provinces of Vietnam from 2010 to 2014 was used, collected from the Vietnam access to resources household survey. To measure the gender gap in the gross value of rice yield, two-stage least squares and Blinder – Oaxaca decomposition methods were used.
Findings
The gross value of rice productivity of male-headed households was 10.3 percent higher than that of female-headed households. The gender gap in rice productivity is caused by the endowment and structural effects; the endowment effect explained 53 percent of the gender gap in rice productivity and the structural effect 42 percent.
Practical implications
In order to reduce the gender gap and improve the gross value of rice yield, the following policies are suggested: female education and access to institutional services (extension and credit) should be improved and future research is needed to determine the reasons for gender discrimination in the agricultural production system.
Originality/value
The findings suggest that the difference in the gross value of rice yield between male- and female-headed households were mainly caused by endowments and returns from those endowments.
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Yejun Wu, Xiaxian Wang, Peilin Yu and YongKai Huang
The purpose of this research is to achieve automatic and accurate book purchase forecasts for the university libraries and improve efficiency of manual book purchase.
Abstract
Purpose
The purpose of this research is to achieve automatic and accurate book purchase forecasts for the university libraries and improve efficiency of manual book purchase.
Design/methodology/approach
The authors presented a Book Purchase Forecast model with A Lite BERT(ALBERT-BPF) to achieve their goals. First, the authors process all the book data to unify format of books' features, such as ISBN, title, authors, brief introduction and so on. Second, they exploit the book order data to label all books supplied by booksellers with “purchased” or “non-purchased”. The labelled data will be used for model training. Last, the authors regard the book purchase task as a text classification problem and present a model named ALBERT-BPF, which applies ALBERT to extract text features of books and BPF classification layer to forecast purchased books, to solve the problem.
Findings
The application of deep learning in book purchase task is effective. The data the authors exploited are the historical book purchase data from their university library. The authors’ experiments on the data show that ALBERT-BPF can seek out the books that need to be purchased with an accuracy of over 82%. And the highest accuracy reached is 88.06%. These indicate that the deep learning model is sufficient to assist the traditional manual book purchase way.
Originality/value
This research applies ALBERT, which is based on the latest Natural Language Processing (NLP) architecture Transformer, to library book purchase task.